Printing medium, method for producing a printing medium, composition, and uses of a composition and

专利摘要:
PRINT MEDIA, METHOD FOR PRODUCING A PRINT MEDIA, COMPOSITION, AND USES OF A COMPOSITION AND PRINT MEDIA. The present invention relates to a printing medium and a method for producing such a printing medium. In particular, the present invention is directed to a printing medium, which comprises a substrate having a first side and a reverse side, and at least one coating layer on the sides of the substrate.
公开号:BR112015004795B1
申请号:R112015004795-5
申请日:2013-09-19
公开日:2022-02-01
发明作者:Matthias Buri；Daniel Gantenbein；Jan Philipp Weihs；Oliver Patrick Grossmann；Philipp Hunziker；Patrick A.c. Gane
申请人:Omya International Ag；
IPC主号:

专利说明:

printing medium
[001] The present invention relates to the field of printing and even more specifically to a printing medium, a method for producing such a printing medium, and a composition for producing a printing layer for such a printing medium.
[002] Flexography is a printing technique, which uses flexible embossed plates. It essentially constitutes a modern version of the letter printing technique, which can be used to print on almost any type of substrate, including plastic, metallic films, cellophane and paper. Generally speaking, a flexo printing is performed by creating a positive mirror master of the required image as a three-dimensional relief, for example, on a rubber or polymer material. The ink, which can be water-based, is then transferred from an ink chamber to a so-called anilox roller (or meter roller), whose texture retains a specific amount of ink as it is coated with thousands of cells. small, which allow him to dose the ink to the printing plate, in a uniform thickness, in a uniform and fast way. A metal scraper, so called a scraper blade, removes excess ink from the anilox roller before the ink is transferred to the printing plates. The substrate is then finally fed between the plate and the print cylinder to transfer the image. In which cases, subsequent process stages (such as polychromatic printing, punching, die cutting, crest formation, etc.) require a dry surface, drying stages may be included.
[003] In contrast to other printing techniques, such as rotogravure or offset printing, flexography typically uses much higher amounts of ink, depending on the total amount of colors. This can lead to problems during the printing process, especially in the case of color printing applications. In order for the final image to be reproduced, typically multiple layers of ink are essential. This process usually requires the ink to be immobilized before the next printing or converting stage is applied to the substrate. Furthermore, the use of water-based inks becomes increasingly relevant in flexography, in order to eliminate the pollution produced by organic solvents. Such water-based inks, however, require a substrate that is capable of absorbing the ink solvent very quickly, as water-based inks have a tendency to bleed, leak, and smear. It is also typical in post-print wet-on-wet-in-line flexography that the printed substrates are additionally post-processed to the final print product, e.g. through cutting, cresting, creasing or gluing, without any intermediate drying stages.
[004] Currently, flexographic paper-based print media are produced, which remain or uncoated, but which have a top layer of white or recycled fiber, or are coated with a layer of white pigment. These printing media are known in the art as schrenz, test coat, white top coat or white top test coat. Uncoated substrates can be printed without intermediate drying between each print unit. However, these uncoated substrates have a matte surface, and thus do not allow for the production of high quality glossy prints. Coated substrates, which are capable of providing glossy prints, however, require an intermediate drying stage between each printing unit, as the ink is not absorbed quickly enough. Without an intermediate drying stage, ink smearing in the next printing unit, conveyor belts, and processing facilities would then be caused, in the varnish application.
[005] EP 2 395 148 A1 describes a process for producing a coated paper, which comprises an application layer having a specific pore structure. A process for coating papers at a pH of 4 to 5 with a crosslinked anionic polymer, and the use of such papers in flexographic printing is disclosed in US 5,229,168 B1. US 2008/02802026 A1 relates to a coating board with a porous coating composition for printing applications. A mineral composition, in particular for use in paper fillers and paper or plastic coatings, is described in ES 2 465 903 A1.
[006] However, there is still a need in the art for a printing medium, which is suitable for flexography, and which allows the reproduction of prints with good quality, in high productivity.
[007] Thus, it is an object of the present invention to provide a printing medium, which is suitable for flexography, preferably for wet-on-wet and/or post-print flexography, and which reduces significantly, the problems of the prior art. It is further desirable that a printing medium be provided which absorbs the transferred ink sufficiently quickly, and thus which can then be used in printing applications, for example in prepress or post flexography. -printing, without any intermediate drying stages being required. It is also desirable that a printing medium be provided, which can be used in flexography, at the same speeds as the uncoated white topcoat, without smearing and smearing being produced, and thus, which can still allow high productivity. . It is also desirable that a printing medium be further provided, which is capable of absorbing large amounts of ink, and in particular flexographic ink, without smearing in subsequent processing units.
[008] It is also an object of the present invention to provide a printing medium that can replace uncoated substrates in printing applications, and especially in flexographic printing applications, without changing the machine's adjustment. of the printing system.
[009] It is also an object of the present invention to provide a printing medium with improved sheet gloss, print gloss, and luminosity, which allows for the production of high quality prints, in particular high quality flexographic prints. .
[0010] The foregoing objects and still others are solved by means of a printing medium, which comprises a substrate having a first side and a reverse side, wherein the substrate comprises at least on the first side at least one permeable coating layer, comprising pigment particles, wherein said pigment particles, whether in the form of a compacted bed, allow for a monomodal pore diameter distribution, a defined polydispersity in volume, expressed as the total width of half the maximum height (FWHM) from 36 to 80 nm, and a volume-defined average pore diameter of 30 to 80 nm.
[0011] In accordance with another aspect of the present invention, there is provided a method for producing a print medium, the method comprising the steps of: a) providing a substrate having a first side and a reverse side, and b) applying a coating composition comprising pigment particles and at least one coating binder on the first side of the substrate so that a permeable coating layer is formed,
[0012] Wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, a defined polydispersity in volume, expressed as the total width at half maximum height (FWHM) from 36 to 80 nm, and a volume-defined average pore diameter of 30 to 80 nm.
[0013] In accordance with yet another aspect of the present invention, a composition, comprising pigment particles, is provided, wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution. , a volume-defined polydispersity, expressed as full width at half maximum height (FWHM) from 36 to 80 nm, and a volume-defined average pore diameter from 30 to 80 nm.
[0014] In accordance with yet another aspect of the present invention, the use of a composition, comprising pigment particles, in a printing application is provided, wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, a volume defined polydispersity expressed as full width at half maximum height (FWHM) from 36 to 80 nm, and a volume defined pore diameter from 30 to 80 nm.
[0015] Advantageous embodiments of the present invention are defined in the corresponding subclaims.
[0016] According to a further embodiment, the substrate is selected from paper, cardboard, containerboard, plastic, cellophane, textile, wood, metal, or concrete, and preferably paper, cardboard, or cardboard for container. According to yet another embodiment, the substrate comprises at least one permeable coating layer on the first side and on the reverse side. According to a further embodiment, the substrate is structured by at least two sub-layers, preferably by three, five or seven sub-layers. According to another embodiment, the substrate is pre-coated, preferably with precipitated calcium carbonate, modified calcium carbonate, or crushed calcium carbonate, or with mixtures thereof.
[0017] In accordance with yet another embodiment, the pigment particles are selected from calcium carbonate, plastic pigments, such as plastic pigments based on polystyrene, titanium dioxide, dolomite, calcined clay, non-calcined clay (hydrosa ), bentonite, or even mixtures thereof, and preferably calcium carbonate and even more preferably precipitated calcium carbonate. According to another embodiment, the pigment particles, when in the form of a compacted bed, have a defined polydispersity by volume, expressed as full width at half maximum height (FWHM) from 40 to 80 nm, and in a manner preferably from 45 to 75 nm, and even more preferably from 50 to 70 nm. In accordance with yet another embodiment, the pigment particles, when in the form of a compacted bed, have a volume-defined average pore diameter of 35 to 75 nm, and preferably 40 to 70 nm.
[0018] According to yet another embodiment, the pigment particles, when in the form of a compacted bed, have a total specific vacuum volume introduced from 0.20 to 0.50 cm3/g, and preferably of 0.25 to 0.48 cm 3 /g, even more preferably 0.30 to 0.55 cm 3 /g, and even more preferably 0.35 to 0.40 m 3 /g. According to yet another embodiment, the pigment particles have a specific surface area of 10 to 30 m 2 /g, and preferably 15 to 25 m 2 /g. In accordance with yet another embodiment, the pigment particles have a weight average particle size d50 of 0 522 µm. preferably from 20 to 250 nm, and even more preferably from 50 to 240 nm, and even more preferably from 70 to 230 nm.
[0019] According to yet another embodiment, the coating layer further contains a coating binder, preferably in an amount of 1 to 20% by weight, based on the total weight of the pigment particles, and a preferably from 3 to 15% by weight, and even more preferably from 6 to 12% by weight. In yet another embodiment, the coating binder is selected from starch, polyvinyl alcohol, styrene-butadiene latex, styrene-latex or polyvinyl acetate latex, or from mixtures thereof, and is, preferably a styrene-butadiene latex.
[0020] According to a further embodiment, the coating layer has a coating weight of from 1 to 50 g/m2, preferably from 2 to 40 g/m2, more preferably from 3 to 30 g/m2, and even more preferably from 5 to 20 g/m 2 . In accordance with yet another embodiment, the coating layer further comprises a rheology modifier, in an amount of less than 1% by weight, based on the total weight of the pigment particles. According to yet another embodiment, the coating layer has a permeability of more than 0.2 x 10-17m 2 , preferably 0.3 x 10-27 m 2 to 3.0 x 10-17 m 2 , and even more preferably from 0.4 x 10 -17 to 2.5 x 10 -17 m 2 . In accordance with yet another embodiment, the print medium is a flexographic print medium.
[0021] According to a further embodiment, the coating composition used in the method according to the invention is a liquid coating composition and the method further comprises a stage c) of drying the coating layer. According to yet another embodiment, stages b) and c) are also carried out on the reverse side of the substrate, in such a way that a printing medium is manufactured by being coated on the first side and on the reverse side. In accordance with yet another embodiment, stages b) and c) are carried out a second time using the same or a different liquid coating composition.
[0022] According to a further embodiment, the coating composition used in the method according to the invention to form the coating layer has a solids content of 10 to 80% by weight, preferably 30 to 75% by weight, even more preferably from 40 to 70% by weight, and even more preferably from 45 to 65% by weight, based on the total weight of the liquid coating composition. In accordance with yet another embodiment, the liquid coating composition has a Brookfield viscosity in the range of 20 to 3000 mPa.s, preferably from 250 to 3000 mPa.s, and even more preferably from 1000 to 2500 mPa.s. .s.
[0023] According to another embodiment, the coating composition used in the method according to the invention is a dry coating composition and stage b) is also carried out on the reverse side of the substrate for the manufacture of a coating medium. printing being coated on the first side and on the reverse side. According to yet another embodiment, stage b) is also carried out a second time using the same dry coating composition or using a different dry coating composition.
[0024] According to yet another embodiment, the coating composition used in the method according to the invention is applied by means of high-speed coating, metering sizing press, curtain coating, spray coating, with blade, or electrostatic coating.
[0025] According to yet another embodiment, the composition according to the invention is a liquid or dry coating composition. According to another embodiment of the printing application, in which the composition according to the invention is used, is a flexographic printing application, preferably the manufacture of a coated flexographic printing medium.
[0026] It is further understood that, for the purpose of the present invention, the following terms have the following meaning:
[0027] Rctc q rtqr„ukVq fc rtgugpVg kpxgp>«q. q Vgtoq “Vczc fg cduqt>«q” fi woc ogfkfc for the amount of liquid, which can be absorbed by a coating layer within a given period of time. As used herein, the absorption rate is expressed as the linear relationship between V(t)/A and At, whose gradient is:

[0028] Where m(tI is the mass absorption in time period t, as defined through a volume V(t) of liquid of density p. The data are normalized with respect to the cross-sectional area of the sample, A, such that the data becomes V(t)/A, the volume absorbed per unit cross-sectional area of the sample. The gradient can then be obtained directly from the plotted data via linear regression analysis, and gives an absorption rate of liquid absorption. The absorption rate is specified in ms-0.5. An apparatus, which can be used to determine the absorption rate, is described in Uejqgnmqrh gV cL “OgcuwtgognV anf pgVyqtm modeling of liquid permeation into compacted mineral bloemu.” *Lqwtpcn of Colloid and Interface Science 2000, 227 (1), 119-131).
[0029] Q Vgtoq “rguq dcug”, VcL eqoq wucfq nc rtgugnVg invention, is determined in accordance with DIN EN ISO 536: 1996, and is defined as the weight in g/m2.
[0030] Q Vgtoq “VknVc”, VcL eqoq wucfq nc rtgs present invention, consists of a combination of at least one pigment, at least one paint binder, water as a carrier liquid, and, optionally, with respect to water, a smaller amount of organic solvent. In addition, the ink may optionally further contain other additives, which are well known to those skilled in the art. For example, the ink may also contain surfactants, which improve the wetting of the surface or coating layer of the print medium. Q Vgtoq "écglutkiKiPtg fg VkiVa", Val eqoq used in the present invention, consists of a compound, which is used to jointly bind one or more ink pigment particles, and to provide their adhesion to the substrate surface. .
[0031] Q Vgtoq "ailwVkpapVg fg tgxguVkogpVq", as used in the present invention, consists of a compound, which is used to bond together two or more materials in mixtures, e.g. coating pigment particles , contained in said coating composition, and allow it to adhere to the surface material of a substrate.
[0032] Q Vgtoq “Iwokpqukfafg”, Val eqoq wuafq pq eqpVgzVq f the present invention, consists of a measurement of the percentage of diffused light, reflected from a surface of a substrate. A brighter leaf reflects more light. As used herein, the luminosity of the substrate can then be measured at an average wavelength of light of 457 nm in accordance with DIN 53145 - 2:2000 or in accordance with ISO 2469:1994, and is specified in percentage , with respect to the defined standard.
[0033] For purposes of the present invention, the term "tgxguVkogpVq" refers to one or more layers, covers, films, films, etc., formed, created, prepared, etc., from a coating composition, which remains predominantly on the surface of the print medium.
[0034] Rata qu rtqr„ukVqu fa rtgugpVg kpxgp>«q, q Vgtoq “dtkljq” refers to the ability of a substrate to reflect some portion of incident light at the mirror angle. Q Vgtoq “dtkljq fa foil” refers to the gloss of the unprinted substrate, while q “dtkljq fg print” tghgtg refers to the gloss of the printed areas of the substrate. Brightness can then be based on a measurement of the amount of light specularly reflected from the surface of a substrate at an adjustment angle, for example at 75°, such that in the case of 75° brightness e is specified as a percentage. Gloss can be determined according to EN ISO 8254 - 1: 2003.
[0035] “EctdqpcVq fg eánekq oqífq” *IEE+, in the meaning of the present invention, is a calcium carbonate, obtained from natural sources, such as limestone, marble, calcite, gypsum or dolomite, and processed through a treatment wet and/or dry, such as milling, sieving and/or fractionation, for example through a cyclone or classifier.
[0036] “EctdqpcVq fg eánekq oqfkfíecfq” *OEE+, because ukipkfíecfq fc the present invention, can be characterized by a natural ground or precipitated calcium carbonate, with an internal structure modification or a surface reaction product.
[0037] Go vqfq q rtgugpvg fqewogpvq, q “vcocpjq fg rctvíewnc” fg a pigment particle is described through the particle size distribution. The dx value represents the diameter over which x% by weight of the particles have diameters of less than dx. This means that the d20 value is a particle size at which 20% by weight of all particles are smaller, and the d75 value is the particle size at which 75% of all particles are smaller. The d50 value is therefore the weight average particle size, i.e. 50% by weight of all particle grains are larger or smaller than this particle size. For the purpose of the present invention, particle size is specified as weight average particle size d50, unless otherwise indicated. To determine the weight average particle size, the d50 value for particles having a d50 value of between 0.2 and 5 μm, a Sedigraph 5100 or 5120 device, from Micromeritics Company, USA, can be used.
[0038] In the context of the present invention, q Vgtoq “rqtq” fgxg ugt understood as describing the space that is found between the pigment particles, i.e., that is formed by the pigment particles and that allows the passage or absorption of fluids . Pore size can be defined rqt ugw “fkâogVtq fg rqtq ofifkq fghrnkfq go xqnwog”, VC eqoq cdckzq described.
[0039] Furthermore, in the context of the present invention, the term "xqnwog fg xáewq gurgeífíeq VqVcn kpVtqfwzkfq" fgxg ugt gpVgpfkfq eqoq described the measured pore volume (which is found between the pigment particles) per unit mass of sample containing the particles of pigment. The total specific vacuum volume introduced can be measured by mercury porosimetry using a Micrometrics Autopore IV mercury porosimeter.
[0040] Furthermore, in the context of the present invention, the term "xqnwog fg xáewq gurgeífíeq total kpVtqfwzkfq" fgxg ugt ckpfc gpVgpfkfq as describing the measured pore volume (which is found between the pigment particles) per unit mass of the sample containing the pigment particles. The total specific vacuum volume introduced can be measured by mercury porosimetry using a Micrometrics Autopore IV mercury porosimeter.
[0041] An exemplary mercury porosimetry experiment entails evacuating a porous sample to remove trapped gases, after which the sample is surrounded with mercury. The amount of mercury displaced by the sample allows the calculation of the volume by mass of the sample, Vmass. Pressure is then applied to the mercury so that it is then introduced into the sample through the pores connected to the outer surface. The maximum applied pressure of mercury can be 414 Mpa, equivalent to a Laplace throat diameter of 0.0004 μm. The data can then be corrected using Pore-Comp (PAC Icpg gV aL “Xqkf Space Structure of Compressible Polymer Spheres and Consolidated Calcium Carbonate Paper-EqcVkPi HqtowlaVkqnu”, Industrial and Engineering Chemistry Research 1996, 35(5):1753 -1764) for mercury and penetrometer effects, and also for sample compression. By taking the first derivative of the cumulative intrusion curves, pore distributions based on equivalent Laplace diameter, inevitably including pore shielding, are then revealed. The total specific vacuum volume introduced corresponds to the vacuum volume determined by mercury porosimetry.
[0042] Q Vgtoq “fkuVtkdwk>«q fg Vcocnhq fg rqtq oqnqoqfal”, Vai as used here, refers to a collection of pores, which have a single clearly discernible maximum on a pore size distribution curve (intensity in ordinate or y-geometric axis, and pore size logarithmically arranged on the abscissa or x-geometric axis).
[0043] Pq rtgugnVg eqnVgzVq, q Vgtoq “fkâogVtq fg rqtq ogfkanq fgfinkfq go xqlwog” ktá ug tgfgtkt to the pore size, below which 50% of the total specific pore volume is introduced into a defined equivalent capillary diameter, thinner than the Young-Laplace equation, where the Young-Laplace equation is applied to the mercury intrusion curve obtained, for example, through the mercury porosimetry experiment described above. Woa fgfknk>«q fq Vgtoq “fkâogVtq fg median volume defined rqro can be found in Ridgway et al. “Oqfkfigf calcium carbonate coatings with rapid absorption and extensive ikswkf wrVamg earaekV{” *Eqiiqkfu and Surfaces A: Physiochem. and Eng. Asp. 2004, 236 (1-3), 91-102).
[0044] The term “pore size rqikfkurgtuadkiity defined in xqiwog” fgxg ugt understood as a characteristic, which describes the breadth of distribution of pore size diameters, to be found between the pigment particles. For the purpose of the present invention, the defined pore size polydispersity in volume is then expressed as the total width at the maximum half of the peak distribution of Vcocpjq fg rqtq únkeqo Woc "width VqVcn nc ogVcfg oázkoc (HYI IM)” fi an expression the extent of a function, given by the difference between the two extreme values of the independent variable, where the independent variable is equal to half its maximum value. The technical term full width at half maximum, or FWHM, is used to approximate the distribution diameter of most pores, i.e. the polydispersity of pore sizes.
[0045] Q Vgroq "fgnukfcfg fg print „rVkec”, Vcl eqoq cswk wucfq in the context of the present invention is a measure of the extent to which a printed area transmits selected filtered light. Optical density is a dimension to the distributed concentration the thickness of the color layer above the substrate Optical print density can be measured in accordance with DIN 16527-3: 1993-11 using a SpectroDens Spectrophotometer from Techkon, Konigstein, Germany.
[0046] Wo "rkiognvq" nq ukinkhkecfq fc rtgugnvg invention may be a mineral pigment or a synthetic pigment. For the purpose of the present invention, wo "rkiognvq okngtcl" is a solid substance having a defined inorganic chemical composition and a crystalline structure and / or characteristic amorphous, whereas a “rkgogntq uknVfiVkeq” qrgânkeq is, for example, a plastic pigment, based on a polymer.
[0047] For the purpose of the present invention, the monomodal pore diameter distribution, the volume defined polydispersity expressed as FWHM, the volume defined median pore diameter, and the total specific vacuum volume introduced of the pigment or pigment composition coating are determined when the pigment or coating composition is in the form of a compacted bed, i.e. in the form of a tablet formulation. A detailed description for preparing a packed bed or tablet formulation from suspensions or pastes of pigment or coating composition can be found in Ridgway et al. “Modified calcium carbonate coatings with rcrif cduqtrVkqp cpf gzVgpukxg nkswkf urtakg ecrcekty” *Eqnnqkfu cpf Surfaces A: Physiochem. And Eng. Asp. 2004, 236 (1-3), 91-102).
[0048] For the purpose of the present invention, the term "rgtogadinifafg" tghgtg refers to the ease with which a liquid can flow through a tablet of the coating composition or coating layer. As used herein, permeability is expressed in terms of the Darcy permeability constant, k, as:

[0049] Where dV(t)/dt is defined as the flow or volume flow rate per unit cross-sectional area, A, FP is the applied pressure difference across the sample, j is the viscosity of the liquid and l is the length of the sample. Data are reported in terms of k in m2. A detailed description of a permeability measurement method can be found in Ridgway et al. “C pgy ogvjqf hqt ogauwtipi vjg niswif permeability of coated and uncoated papers and dqatfu” *Pqtfie Pulp and Paper Research Journal, 2003, 18 (4), 377-381).
[0050] Woa eaoafa fg tgxguViogpVq "rgtogáxgf', in the meaning of the present invention, refers to a coating layer, which is capable of absorbing ink, which has been applied to said coating layer. Preferably, a permeable coating layer has a permeability of more than 0.2 x 10-17 m 2 .
[0051] “Eatdqpavq fg eáneiq rtgeirivafq” *REE+ pq uiipihieafq of the present invention, is an inorganic synthesized material, generally obtained through precipitation, following a reaction of carbon dioxide and calcium hydroxide (hydrated lime) in an aqueous environment or by precipitating a source of calcium and carbonate in water. Additionally, the precipitated calcium carbonate can also be the product of introducing calcium and carbonate salts, calcium chloride and sodium carbonate, for example, into an aqueous environment.
[0052] For the purposes of the present invention, wo “oqfkfiecfqt de tgqnqikc” fi wo cfkvkxq. which alters the rheological behavior of a suspension or liquid coating composition in order to meet the required specifications for the coating method employed.
[0053] Woc "átgc uwrgtfkekcn gurgeífíec *UUC+" fg a mineral pigment in the meaning of the present invention is further defined as the surface area of the mineral pigment, divided by the mass of the mineral pigment. As used herein, specific surface area is measured by adsorption using the BET isotherm (ISO 9277: 2010), and is specified in m 2 /g.
[0054] Woc “uwurgpu«q” qw “rcuVc”, pq ukipkfkecfq fc rtgugpVg invention, comprises insoluble solids and water, and optionally still other additives and usually contains large amounts of solids, and therefore Accordingly, it is more viscous and may have a higher viscosity than the liquid from which it is formed.
[0055] In the present context, the term “uwduVtcVq” fgxg ugt ckpfc understood as any material, having a surface suitable for printing or painting on it, such as paper, cardboard, container board, plastic, cellophane, textile, wood , metal or concrete.
[0056] For the purposes of this kpxgp>«q, c “gurguuwtc” fg woc layer refers to the thickness of a layer after the applied coating composition forming the layer has dried.
[0057] For purposes of the present invention, the term "xkuequkfcfg" when referring to liquid coating compositions, refers to Brookfield viscosity. Brookfield viscosity can be measured using a Brookfield viscometer at 23°C, 100 rpm, and is specified in mPa.s.
[0058] For the purposes of the present invention, the term "xkuequkfcfe", eqo tefetêpekc and printing inks, refers to a cup of viscosity of 4 mm DIN. The measured viscosity of the 4 mm DIN beaker characterizes the period of time, in seconds, that a defined volume of paint needs to be drained through a 4 mm nozzle of said beaker, as described in DIN EN ISO 2341-2012- 03.
[0059] For prqr„ukVq fc rteuepVe kpxep>«q, q Vetoq “rré-korteuuq” refers to the printing application, preferably a flexographic printing application, in which the facing paper of a product of The print, which comprises a layered substrate, is printed separately and is subsequently conjugated to the multi-layered product, such as, for example, the final corrugated board, for example by gluing and/or die-cutting.
[0060] “R„u-korteuu“q”, in the meaning of the present invention, refers to a printing application, preferably a flexographic printing application, in which a substrate is printed, which already represents the final print product (substrate). For example, a substrate, comprising at least two or three underlayers, such as corrugated board, can be printed in a post-printing process.
[0061] Wo “rtqeeuuq eo nknjc”, pq ukipkfíecfq fc rteuepVe invention, refers to a printing application, preferably a flexographic printing application, in which a printing machine is used, in which all stations of color and optionally other post-press production stages are placed in series, and in a special way horizontally in series.
[0062] In the present context, q Vetoq "humifq-on-uokfq" refers to a polychromatic printing application, preferably a polychromatic flexographic printing application, in which individual colors are subsequently printed onto the substrate, without any intermediate drying.
[0063] Swcpfq q Vgtoq “eqortggpfgpfq” is used in the present description and in the claims, it does not exclude other elements. For the purposes of the present invention, q Vgtoq "eqpukuVkpfq fg" fi eqpukfgtcfq as being a preferred embodiment of the term "eqortggpfgpfq" Ug cswk c following a group is defined as comprising at least a number of embodiments, this is also understood as exposing a group, preferably consisting only of these modalities.
[0064] When an article, definite or indefinite, is used with reference to a singular noun, for example, “wo”, “woc” qw “q”. guVg includes a plural of that name, unless something else is specifically mentioned.
[0065] Qu Vgtoqu “qdVgpíxgF’ qw “fghrníxgn” g “qdVkfq” qw “fghmkfq” are used interchangeably. This means that unless the context clearly dictates it from a qwVtq oqfq. q Vgtoq “qdVkfq” p«q ukipkhkec indicate that a modality needs to be obtained through, for example, the stage sequence swg ugiwgo q Vgtoq “qdVkfq”. even if such an understandmgpVq nkokVcfq guVglc ugortg kpenwífq rgnqu Vgtoqu “qdVkfq” qw “fghkpkfq” eqoq woc preferred modality.
[0066] The printing medium according to the invention comprises a substrate having a first side and a reverse side. The substrate comprises, at least on the first side, at least one permeable coating layer comprising pigment particles, said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution. , a volume-defined polydispersity, expressed as full width at a half maximum height (FWHM) of 36 to 80 nm, and a volume-defined median pore diameter of 30 to 80 nm. Optionally, the print medium may further comprise at least one permeable coating layer on the reverse side of the substrate. Preferably, the print medium is a flexographic print medium.
[0067] In the following, the details and preferred embodiments of the printing medium according to the invention will be set out in more detail. It is to be further understood that these technical details and embodiments also apply to the method according to the invention for producing said printing medium, the composition according to the invention, and the use thereof. Substrate
[0068] The printing medium of the present invention comprises a substrate having a first side and a reverse side. The substrate may further serve as a support for the permeable coating layer and may be opaque, translucent, or transparent.
[0069] In accordance with a further embodiment of the present invention, the substrate is selected from paper, cardboard, container board, plastic, cellophane, textile, wood, metal or concrete.
[0070] According to a further preferred embodiment of the present invention, the substrate is paper, cardboard or container board. The paperboard may further comprise a board board or a box board, corrugated board or non-packaging board, such as chrome board or design board. The container board may further comprise lining board and/or a corrugated medium. Both coating board and corrugating medium are used to produce corrugated board. The paper, cardboard, or container board substrate may have a basis weight of 10 to 1000 g/m 2 , 20 to 800 g/m 2 , 30 to 700 g/m 2 , or 50 to 600 g/m 2 .
[0071] According to yet another embodiment, the substrate is a plastic substrate. Suitable plastic materials are, for example, polyethylene, polypropylene, polyvinyl chloride, polyesters, polycarbonate resins or fluorine-containing resins. Examples for suitable polyesters are poly(ethylene terephthalate), poly(ethylene naphthalene) or poly(ester diacetate). An example for a fluorine-containing resin is poly(tetrafluoro ethylene). The plastic substrate may be filled with a mineral filler, an organic pigment, an inorganic pigment, or mixtures thereof.
[0072] The substrate may further consist of only one layer of the aforementioned materials or may further comprise a layered structure having several sub-layers of the same or different materials. In accordance with yet another embodiment, the substrate is layered. In accordance with yet another embodiment, the substrate is structured by at least two sublayers, preferably three, five or seven sublayers. Preferably, the sub-layers of the substrate are made of paper, cardboard, container board, and/or plastic.
[0073] According to a further exemplary embodiment, the substrate is structured by two sub-layers, which comprise a flat sub-layer and a sub-layer having a non-planar structure, for example, a corrugated structure. In accordance with yet another exemplary embodiment, the substrate is structured by means of three sub-layers, which comprise two flat outer sub-layers and an intermediate sub-layer having a non-planar structure, for example, a corrugated structure. According to yet another exemplary embodiment, the substrate is structured by five sublayers, comprising two planar outer sublayers, a planar intermediate sublayer, and between the outer sublayer and the intermediate sublayer, two sublayers having a non-planar structure, for example, a corrugated structure. In accordance with yet another embodiment, the substrate is structured by means of seven sublayers, which comprise two flat outer sublayers, two planar intermediate sublayers, and three sublayers having a non-planar structure, for example a corrugated structure, wherein the two non-planar sub-layers are between the outer sub-layer and the intermediate sub-layers, and the non-planar sub-layer is between the two intermediate sub-layers. However, the substrate of the print medium according to the present invention may also comprise any other suitable single-layer or multi-layer structure.
[0074] A print medium, which comprises a substrate, which consists of only one layer, may be subjected to a flexographic pre-printing process, in which the print medium is printed and subsequently assembled as a product, which comprises at least least two sublayers, wherein the substrate is used as an outer sublayer of said product. For example, such a printed media can be further used as an outer covering of a corrugated fiberboard or a cardboard. In this case, such a pre-printed media could represent the outer sublayer(s) (2) and/or (4) of the layered structures shown in Figures 2, 3 and 4.
[0075] A substrate, which is subjected to a flexographic prepress process, can have a thickness of from 0.04 to 10 mm, from 0.06 to 1 mm, or from 0.05 to 0.5 mm According to a still preferred embodiment, the substrate has a thickness of 0.1 to 0.3 mm.
[0076] The opposite of the prepress process is the flexographic postpress process, in which a print medium, comprising a substrate, which is structured through at least two sublayers, is printed. It is further advantageous to combine post-printing in an in-line printing process, with post-print production stages such as folding or cutting the media.
[0077] In accordance with yet another embodiment, the substrate is pre-coated, preferably with a carbonate, and even more preferably with a calcium carbonate, and even more preferably with a precipitated calcium carbonate, carbonate of modified calcium or ground calcium carbonate, or with mixtures thereof. Such a precoat can further improve the optical print density and print gloss of the media according to the invention. pigment particles
[0078] The permeable coating layer of the printing medium according to the invention comprises pigment particles, which, when in the form of a compacted bed, have a monomodal pore diameter distribution, a polydispersity defined in volume as in width. half maximum height (FWHM) of 36 to 80 nm, and a defined volume median pore diameter of 30 to 80 nm.
[0079] The inventors have surprisingly found that the speed of ink absorption during printing applications, especially during flexography, can be further increased if the substrate is coated with a layer comprising the pigment particles according to the invention with the properties defined above. Furthermore, the retention of ink molecules on the surface of the substrate can be improved by coating the substrate with a layer comprising the pigment particles according to the invention, which in turn leads to a density of highest optical print. The print sheet and substrate gloss can also be improved. In particular, the inventors have found that, especially in the case of flexographic printing applications, it is possible to obtain better control of the speed of absorption of ink solvents through the composition of the pigment particles according to the invention, when using of a monomodal pore diameter distribution. Without being bound by any theory, it is also believed that a better control of the ink absorption rate is still obtained by means of a uniform pore size, expressed by the polydispersity range defined in volume defined above.
[0080] According to a further embodiment of the present invention, said pigment particles, when in the form of a compacted bed, have a defined polydispersity in volume, expressed as the full width at half maximum height (FWHM) of 40 to 80 nm, and preferably from 45 to 75 nm, and even more preferably from 50 to 70 nm.
[0081] In accordance with yet another embodiment of the present invention, the pigment particles, when in the form of a compacted bed, have a defined volume median pore diameter of 35 to 75 nm, and preferably of 40 at 70 nm.
[0082] According to yet another embodiment of the present invention, the pigment particles, when in the form of a compacted bed, have a total specific vacuum volume introduced from 0.20 to 0.50 cm 3 /g, of a preferably from 0.25 to 0.48 cm 3 /g, and even more preferably from 0.30 to 0.45 cm 3 /g, and even more preferably from 0.35 to 0.40 cm 3 /g g.
[0083] The pigment particles have a specific surface area of 10 to 30 m 2 /g, and preferably 15 to 25 m 2 /g.
[0084] In accordance with yet another embodiment of the present invention, the pigment particles have a weight average particle size d50 of 0 522 µm. fg wo oqfq rtgfgtkfq fg 20 to 150 nm, even more preferably from 50 to 240 nm, and even more preferably from 70 to 230 nm. Preferably, the weight average particle size d50 is measured using a Sedigraph 5120 from the company Micromeritics, USA. The inventors have surprisingly found that a weight average particle size d50 of between 20 and 300 nm, and in particular between 50 and 250 nm, can further improve the absorption properties of the pigment particles in accordance with with the invention and can further provide improved paper and print gloss.
[0085] In accordance with yet another embodiment of the present invention, the pigment particles are mineral pigment particles. A suitable mineral pigment may be a calcium carbonate, for example in the form of a ground calcium carbonate, a modified calcium carbonate, or a precipitated calcium carbonate, or a mixture thereof. A natural ground calcium carbonate (GCC) can be characterized, for example, by one or more of marble, limestone, gypsum and/or dolomite. A precipitated calcium carbonate (PCC) can be further characterized, for example, by one or more of aragonitic, caterite and/or calcitic mineralogical crystal forms. Aragonite is commonly in an acicular form, while vaterite belongs to the hexagonal crystal system. Calcite can present scalenohedral, prismatic, spherical and rhombohedral shapes. A modified calcium carbonate can be further characterized by a naturally ground or precipitated calcium carbonate with a surface and/or internal structure modification, for example the calcium carbonate can be further treated or coated with a hydrophobic surface treating agent such as than, for example, an aliphatic carboxylic acid or a siloxane. The calcium carbonate can be further treated or coated so that it can be made cationic or anionic with, for example, a polyacrylate or polydiallyldimethyl ammonium chloride (polyDADMAC).
[0086] Preferably, the mineral pigment is a ground calcium carbonate, a modified calcium carbonate, or a precipitated calcium carbonate, or a mixture thereof. According to a particularly preferred embodiment, the mineral pigment is a precipitated calcium carbonate. The inventors have surprisingly found that coating layers comprising the precipitated calcium carbonate can still result in very good substrate coverage and very good opacity. Furthermore, precipitated calcium carbonate can be produced in very narrow monomodal particle size distributions.
[0087] According to yet another embodiment, the calcium carbonate may be further derived from an aqueous suspension of calcium carbonate. In accordance with yet another embodiment of the present invention, the aqueous suspension of calcium carbonate has a solids content of between 10% by weight and 82% by weight, and preferably between 50% by weight. , and 81% by weight, and even more preferably from 50% by weight to 78% by weight, based on the total weight of the aqueous suspension of calcium carbonate. In accordance with yet another preferred embodiment of the present invention, the aqueous suspension of a calcium carbonate is a concentrated aqueous suspension of dispersed calcium carbonate, which preferably has a solids content of between 50% by weight , and 78% by weight based on the total weight of the aqueous suspension of calcium carbonate.
[0088] In addition to calcium carbonate, the coating layer may further comprise other mineral pigments or synthetic pigments. Examples of still further pigment particles comprise silica, alumina, titanium dioxide, clay, calcined clays, barium sulfate or zinc oxide.
[0089] Examples of synthetic pigments include plastic pigments, such as styrene pigments (eg, RopaqueTM AF-1353, commercially available from Dow Chemical).
[0090] However, instead of calcium carbonate, the pigment particles can be further selected from any other pigment particles, which, when in the form of a compacted bed, have a monomodal pore diameter distribution, a volume-defined polydispersity, expressed as full width at half maximum height (FWHM) from 36 to 80 nm, and a volume-defined average pore diameter from 30 to 80 nm.
[0091] According to yet another exemplary embodiment of the present invention, the pigment particles are selected from calcium carbonate, from plastic pigments, such as plastic pigments based on polystyrene, titanium dioxide, dolomite, calcined clay, uncalcined (hydrous) clay, bentonite, or mixtures thereof, and preferably calcium carbonate, and even more preferably precipitated calcium carbonate.
[0092] In accordance with another aspect of the present invention, there is provided a composition comprising pigment particles, wherein said pigment particles, when in a form of a compacted bed form, have a monomodal pore diameter distribution. , a volume-defined polydispersity expressed as full width at half maximum height (FWHM) of 36 to 80 nm, and a volume-defined average pore diameter of 30 to 80 cm.
[0093] In accordance with yet another embodiment of the present invention, the composition is a liquid or dry coating composition.
[0094] According to yet another preferred embodiment of the present invention, the pigment particles are selected from precipitated calcium carbonate, wherein said pigment particles, when in the form of a compacted bed, have a polydispersity defined in volume, expressed as the full width at half maximum height (FWHM) from 45 to 75 nm, preferably from 50 to 70 nm, and/or a volume-defined average pore diameter of 35 to 75 nm, and of a preferably from 40 to 70 nm, and/or a total specific vacuum volume introduced from 0.20 to 0.50 cm3/g, preferably from 0.25 to 0.48 cm3/g, and/or wo Vcocpjq fg rcrtiewnc ofifkq go rguq fg 0 522 po. g fg wo preferred mode 20 to 250 nm.
[0095] In accordance with yet another aspect of the present invention, the use of a composition comprising pigment particles in printing applications is provided, wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, and a defined polydispersity in volume, expressed as the total width at a half maximum height (FWHM) of 36 to 80 nm.
[0096] According to yet another embodiment, the printing application consists of a flexographic printing application. A flexographic printing application may be, for example, the manufacture of a coated flexographic printing medium, wherein, preferably, the flexographic printing medium is selected from paper, cardboard, container board, plastic, cellophane , textile, wood, metal or concrete, and preferably paper, cardboard or container board.
[0097] However, the composition of the present invention can still be used in other printing applications, such as offset printing or inkjet printing. coating layer
[0098] The substrate comprises, on at least one first side, at least one permeable coating layer, which comprises the pigment particles. The function of the permeable coating layer is to absorb and transport ink solvent, which is then applied to the print medium in the course of the printing process towards the substrate and in such a way as to retain the ink pigment particles. .
[0099] Ink compositions used in flexography are typically liquid compositions, which comprise a solvent or carrier liquid, dyes or pigments, wetting agents, organic solvents, detergents, thickeners, preservatives, and the like. Preferably, the solvent or carrier liquid is water-based, i.e. the amount of water in the solvent or carrier liquid is greater than the amount of organic solvents and/or volatile organic compounds contained in the solvent or carrier liquid. same. In contrast to inks containing primarily organic solvents and/or volatile organic compounds, water-based inks can still address fewer environmental issues.
[00100] Depending on the composition of the coating layer of the printing medium according to the invention, the printing ink may still require additional additives, such as surfactants, which ensure sufficient wetting of the coating layer. Alternatively or additionally, the coating layer of the printing medium according to the invention may be further composited in such a way that such sufficient wetting is ensured. One skilled in the art knows how to properly select such paint compositions and/or coating layer compositions.
[00101] According to the present invention, the coating layer of the printing medium according to the invention is permeable. According to yet another embodiment of the present invention, the coating layer has a permeability of more than 0.2 x 10-17 m 2 , preferably 0.3 x 10 -17 m 2 to 3.0 x 10 - 17 m 2 , and even more preferably from 0.4 10-17 m 2 to 2.5 x 10-17 m 2 .
[00102] The coating layer preferably has an absorption rate of at least 1.0 x 10 -7 ms-0.5, preferably 1.0 x 10 -7 ms-0.5 to 1, 0 x 10 -2 ms-0.5, and even more preferably from 1.0 x 10 -6 ms-0.5 to 5.0 x 10 -3 ms-0.5, and even more preferably from 1.0 x 10-5 ms-0.5 to 2.5 x 10-3 ms-0.5. The liquid used to determine the absorption rate is hexadecane.
[00103] In accordance with yet another exemplary embodiment of the present invention, the coating layer has a permeability of more than 0.2 x 10-17 m2 and an absorption rate of at least 1.0 x 10-7 ms -0.5, and preferably the coating layer has a permeability of 0.3 x 10 -17 m 2 to 3.0 x 10 -17 m 2 and an absorption rate of 1.0 x 10 -7 ms-0.5 at 1.0 x 10-2 ms-0-5.
[00104] The amount of pigment in the coating layer can be in a range of from 40 to 99% by weight, for example from 45 to 98% by weight and preferably from 60 to 97% , by weight, based on the total weight of the coating layer.
[00105] The coating layer may further contain a coating binder. Any suitable polymeric binder can be used in the coating layer of the invention. For example, the polymeric binder may be a hydrophilic polymer, such that, for example, poly(vinyl alcohol), poly(vinyl pyrrolidone), gelatin, cellulose ethers, poly(oxazolines), poly(vinyl acetamides), poly(acetate) (vinyl alcohol) partially hydrolyzed poly(acrylic acid), poly(acrylamide), poly(alkylene oxide), sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin, chitin, chitosan, dextran, pectin, derivatives of collagen, collodian, agar-agar, arrowroot, guar, carrageenan, starch, tragacanth, xanthan, or rhamsan and mixtures thereof. It is further possible to use other binders such as hydrophobic materials, for example poly(styrene co-butadiene), polyurethane latex, polyester latex, poly(n-butyl acrylate), poly(n-butyl methacrylate), poly(2-ethyl hexyl acrylate) copolymers of n-butyl acrylate and ethyl acrylate, copolymers of vinyl acetate and n-butyl acrylate, and the like.
[00106] According to yet another embodiment, the coating binder is a natural binder selected from starch. In yet another embodiment, the coating binder is a synthetic binder selected from styrene-butadiene latex, styrene-acrylate latex or polyvinyl acetate latex. The coating layer may further contain mixtures of hydrophilic binders and latex, for example a mixture of polyvinyl alcohol and styrene-butadiene latex.
[00107] According to yet another exemplary embodiment of the present invention, the coating binder is selected from starch, polyvinyl alcohol, styrene-butadiene latex, styrene-acrylate latex, or polyvinyl acetate latex, or further from mixtures thereof, and is preferably a styrene-butadiene latex. An example of a styrene-butadiene latex is Litex 9460, commercially available from the company Synthomer.
[00108] In accordance with yet another embodiment of the present invention, the amount of coating binder in the coating layer is from 1 to 20% by weight based on the total weight of the pigment particles, and preferably of 3 to 15% by weight and even more preferably from 6 to 12% by weight.
[00109] The coating layer may also contain optional additives. Suitable additives may comprise, for example, dispersants, milling aids, surfactants, rheology modifiers, lubricants, foam suppressants, optical brighteners, dyes, preservatives, or even pH control agents. In accordance with yet another embodiment, the coating layer further comprises a rheology modifier. Preferably, the rheology modifier is present in an amount of less than 1% by weight based on the total weight of the pigment particles.
[00110] According to yet another exemplary embodiment, the pigment is dispersed with a dispersant. The dispersant can be used in an amount of from 0.01 to 10% by weight, from 0.05 to 8% by weight, from 0.5 to 5% by weight, from 0.8 to 3% by weight weight, or from 1.0 to 1.5% by weight, based on the total weight of the pigment particles. In yet another preferred embodiment, the pigment is dispersed with an amount of 0.05 to 5% by weight, and preferably with an amount of 0.5 to 5%, by weight, of a dispersant, based on in the total weight of the pigment particles. A suitable dispersant is preferably selected from the group comprising homopolymers or copolymers of the carboxylic acid salts based, for example, on acrylic acid, methacrylic acid, maleic acid, fumaric acid or itaconic acid and acrylamide or mixtures of the same. Acrylic acid homopolymers or copolymers are especially preferred. The molecular weight Mw of such products is preferably in a range of 2000 - 15000 g/mol, with a molecular weight Mw of 3000 - 7000 g/mol being especially preferred. The molecular weight Mw of such products is also preferably in a range of 2000 to 150,000 g/mol, and an Mw of 15,000 to 50,000 g/mol is especially preferred, for example from 35,000 to 45 000 g/mol. In yet another exemplary embodiment, the dispersant is a polyacrylate.
[00111] The molecular weight of the grinding aids and/or dispersants is selected in such a way that they do not act as a binder, but rather as a splitting compound. The polymers and/or copolymers may be further neutralized with monovalent and/or polyvalent cations or they may have free acid groups. Such monovalent cations include, for example, sodium, lithium, potassium or ammonium. Suitable polyvalent cations include, for example, calcium, magnesium, strontium or aluminum. Combination of sodium and magnesium is especially preferred. Grinding and/or dispersing aids, such as sodium polyphosphates and/or polyaspartic acid, as well as their alkaline and/or alkaline earth salts, sodium citrate and amines, alkanol amines, such as triethanol amine and triisopropanolamine may further be advantageously used, either alone or in combination with each other. Dispersants based on organometallic compounds can also be used. However, it is also possible to use any other dispersant.
[00112] According to a further exemplary embodiment, the amount of pigment in the coating layer is from 60 to 97% by weight, based on the total weight of the coating layer, the amount of coating binder in the coating layer being 6 to 12% by weight based on the total weight of the pigment particles, and a rheology modifier is still present in an amount of less than 1% by weight based on the total weight of the pigment particles.
[00113] The coating layer may have a thickness of at least 1 μm, for example at least 5 μm, 10 μm, 15 μm or 20 μm. Preferably, the coating layer has a thickness in the range of 1 μm to up to 150 μm.
[00114] According to yet another embodiment of the present invention, the coating layer has a coating weight of from 1 to 50 g/m2, preferably from 2 to 40 g/m2, and more preferably of 3 to 30 g/m 2 , and even more preferably 5 to 20 g/m 2 . Inventive print media manufacturing
[00115] A method for producing a printing medium is provided, the method comprising the stages of: a) providing a substrate having a first side and a reverse side, and b) applying a coating composition, which comprises pigment particles and at least one coating binder on the first side of the substrate so that a permeable coating layer is formed.
[00116] Wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, a defined polydispersity in volume, expressed as the total width at a half maximum height (FWHM) of 36 to 80 nm, and a volume-defined average pore diameter of 30 to 80 nm.
[00117] Preferably, the print medium produced by the method according to the invention is a flexographic print medium.
[00118] The coating composition may be in liquid or dry form. According to yet another embodiment, the coating composition applied in stage b) of the inventive method is a dry coating composition. According to yet another embodiment, the coating composition applied in stage b) of the inventive method is a liquid coating composition. In this case, the method according to the invention comprises a stage c) of drying the coating layer.
[00119] According to yet another embodiment, stage b) of the method is also carried out on the reverse side of the substrate for the manufacture of a print medium being coated on the first side and on the reverse side. This stage can be performed for each side separately or it can be performed on the first side and on the reverse side simultaneously. In accordance with yet another embodiment, where the coating composition is in liquid form, stages b) and c) are also performed on the reverse side of the substrate for manufacturing a print medium being coated on the first side and on the second side. reverse side. These stages can then be performed for each side separately or they can be performed on the first side and the reverse side simultaneously.
[00120] In accordance with yet another embodiment, stage b) is performed a second time or even more times by using a different composition or the same coating composition. According to yet another embodiment, where the coating composition is in a liquid form, stages b) and c) are carried out a second time or even more times, by using a different or the same liquid coating composition. composition.
[00121] The coating layer can be applied over the substrate by conventional coating means commonly used in this technique. Suitable coating methods are, for example, air trowel coating, electrostatic coating, metering size press, film coating, spray coating, wire-wound coating, slot coating, blade hopper coating, engraving, curtain coating, high speed coating and the like. Some of these methods even allow for simultaneous coating of two or more layers, which is preferred from an economic manufacturing perspective. However, any other coating method suitable for forming the coating layer on the substrate could also be used.
[00122] In yet another exemplary embodiment, the coating composition is applied via high speed coating, metering sizing press, curtain coating, spray coating, blade coating or electrostatic coating. In yet another preferred embodiment, high speed coating is still used to apply the coating layer. In yet another preferred method, curtain coating is used to apply the coating layer.
[00123] According to yet another exemplary embodiment, a liquid coating composition is applied by means of high speed coating, metering sizing press, curtain coating, spray coating or blade coating, preferably with curtain. In accordance with yet another exemplary embodiment, a coating composition is applied via electrostatic coating.
[00124] In accordance with yet another embodiment of the present invention, the coating composition used to form the coating layer has a solids content of 10 to 80% by weight, preferably 30 to 75% by weight, more preferably from 40 to 70% by weight, and even more preferably from 45 to 65% by weight, based on the total weight of the liquid coating composition.
[00125] The liquid coating composition may have a Brookfield viscosity in a range of from 20 to 3000 mPa.s, preferably from 250 to 3000 mPa.s, and even more preferably from 1000 to 2500 mPa.s. s..
[00126] In accordance with another embodiment of the present invention, the coating composition, when in the form of a compacted bed, has a monomodal pore diameter distribution. In accordance with yet another embodiment of the present invention, the coating composition, when in the form of a compacted bed, has a defined polydispersity by volume, expressed as the full width at half maximum height (FWHM) from 36 to 80 nm, preferably from 40 to 80 nm, more preferably from 45 to 75 nm, and even more preferably from 50 to 70 nm.
[00127] In accordance with yet another embodiment of the present invention, the coating composition, when in the form of a compacted bed, has a volume-defined average pore diameter of 30 to 80 nm, preferably 35 to 35 nm. 75 nm, and even more preferably from 40 to 70 nm. In accordance with yet another embodiment of the present invention, the coating composition, when in the form of a compacted bed, has a total introduced specific vacuum volume of 0.20 to 0.50 cm 3 /g, preferably of 0.25 to 0.48 cm 3 /g, and even more preferably 0.30 to 0.45 m 3 /g, and even more preferably 0.35 to 0.40 cm 3 /g.
[00128] After coating, the print medium can then be calendered or super calendered in order to increase surface smoothness. For example, calendering can be carried out at a temperature of 20 to 200°C, preferably 60 to 100°C by using, for example, a calender having from 2 to 12 jaws. Said jaws can be hard or soft, the hard jaws, for example, being made of a ceramic material. In accordance with yet another exemplary embodiment, the coated print medium is calendered at 300kN/m2 so that a glossy coating is then obtained. In accordance with yet another exemplary embodiment, the coated print medium is calendered at 120 kN/m2 so that a matte coating is then obtained.
[00129] Examples of print media according to the present invention, which comprise a substrate and at least one coating layer, are shown in Figures 1 to 4.
[00130] In accordance with yet another embodiment, the print medium according to the present invention is used in a flexographic printing application, preferably in a wet-on-wet flexo, and more preferably in a prepress wet-on-wet or in post-press wet-on-wet flexo, and even more preferably in post-press wet-on-wet flexography. However, the printing medium of the present invention can also be used in other printing applications, such as offset printing or inkjet printing.
[00131] The scope and interest of the invention will be further understood on the basis of the figures and examples that follow, which are intended to illustrate certain embodiments of the invention, and which are non-limiting. Description of Figures:
[00132] Fig. 1 - shows a means according to the present invention, which comprises a single layer substrate (2) and a coating layer on the first side of the substrate.
[00133] Fig. 2 - shows a printing medium according to the present invention, which comprises a substrate being structured by means of three sub-layers (2, 3, 4) and a coating layer (1) on the first side of the substrate.
[00134] Fig. 3 - shows a printing medium according to the present invention, comprising a substrate being structured by means of three sub-layers (2, 34) and a coating layer (1) on the first side of the substrate and a coating layer (5) on the reverse side of the substrate.
[00135] Fig. 4 - shows a printing medium according to the present invention, comprising a substrate being structured by means of five sublayers (2, 3, 4, 6, 7) and a coating layer (1) on the first side of the substrate and a coating layer (5) on the reverse side of the substrate.
[00136] Fig. 5 - schematically illustrates the assembly of a laboratory scale printing device used to evaluate the print quality of comparative and inventive test substrates.
[00137] Fig. 6 - schematically illustrates the assembly of an industrial scale printing device, comprising post-press processing units, in order to assess the quality of comparative and inventive test substrates.
[00138] Fig. 7 shows two two-color flexographic test prints run on a uniquely coated media in accordance with the invention (right figure) and a comparative uniquely coated media (left figure).
[00139] Fig. 8 - shows a graph, which illustrates the cumulative distribution of gray scales, evaluated on images of comparative and inventive test substrates.
[00140] Fig. 9 - shows a section of Fig. 8 in a range of 50 to 150 grayscale levels (from 256).
[00141] Fig. 10 shows two two-color flexographic test prints run on a uniquely coated media in accordance with the invention (right figure) and a comparative single-mode coated media (left figure).
[00142] Fig. 11 shows an inkjet print performed on a uniquely coated print medium in accordance with the invention.
[00143] Fig. 12 shows an inkjet print performed on a coated media in a unique, comparative manner. Examples1. measurement methods
[00144] Next, the materials and measurement methods implemented in the examples are described. Particle Size
[00145] The particle size distribution of the pigment particles was measured using a Sedigraph 5120 from the company Micromeritics, USA. The method and instruments are known to those skilled in the art and are commonly used to determine the grain size of fillers and pigments. The measurement was carried out in an aqueous solution comprising 0.1% by weight of Na4P2O7. The samples were then dispersed using a high-speed, supersonic stirrer.Solid content of an aqueous suspension
[00146] The solids content of the suspension (also known as “rguq ugeq”+ fok fgVgtokpcfq rqt ogkq fq wuq fg wo Moisture Analyzer HR 73 from the company Mettler-Toledo, Switzerland, with the following settings: temperature of 120°C, automatic switch 3, conventional drying, from 5 to 20 g of suspension. Brookfield viscosity
[00147] The Brookfield viscosity of the liquid coating compositions was measured after one hour of production and after one minute of stirring, at room temperature, at 100 rpm, using a Brookfield viscometer of the RVT type, equipped with a appropriate spindle. Specific Surface Measurement (BET)
[00148] The specific surface area (in m2/g) of the mineral filler was determined using nitrogen and the BET method, which is well known to those skilled in the art (ISO 9277: 2010). The total surface area (in m2) of the mineral filler was then obtained by multiplying the specific surface area by the mass (in g) of the mineral filler. The method and instrument are known to those skilled in the art and are commonly used in order to determine the specific surface of fillers and pigments. Viscosity of printing inks
[00149] Printing inks have been adjusted to a viscosity of between 18'' to 24'' by measuring the amount of time in seconds that a defined ink volume (4mm DIN cup) requires in order to that can run through the mouth of said cup ( EN ISO 2431: 2012-03). pH measurement
[00150] The pH was measured at 25°C using a Mettler Toledo Seven Easy pH meter and a Mettler Toledo InLab® Expert Pro pH electrode. A three-point instrument calibration (according to the segment method) was then performed using commercially available buffer solutions having pH values of 4, 7 and 10 at 20°C (from Aldrich). The reported pH values were endpoint values detected by the instrument (the endpoint was when the measured signal differed by less than 0.1 mV from the mean during the last 6 seconds). Pigment brightness and paper opacity
[00151] Pigment luminosity and paper opacity were then measured using an ELREPHO 3000 from the Datacolor company in accordance with ISO: 2469:1994 (DIN 53145 - 2: 2000 and DIN 53146: 2000). paper shine
[00152] Paper and print gloss were measured using LGDL-05.2-lab instrumentation from Klehmann Messysteme GmbH, DE-Koblenz, according to EN ISO 8254-1: 2003, TAPPI 75° (%) . Optical print density
[00153] Optical print density was measured using a SpectroDens spectrometer from Techkon GmbH, Germany, in accordance with DIBN 16527-3: 1993-11. Formation of a compacted bed
[00154] A compacted bed or tablet formulation of a pigment was formed on a wet table press apparatus by applying constant pressure (usually 15 bar) to the pigment suspension or paste over several hours of such that water is released through filtration, through a thin 0.025 μm filter membrane, resulting in a compacted bed or a pigment tablet with a diameter of about 4 cm and a thickness of 1 to 1, 5 cm. The tablets obtained can be divided and molded into suitable sample configurations for subsequent analysis. The apparatus used is shown schematically in Ridgway et al. “Oqfkfigf calcium carbonate coatings with rapid absorption and extensive liquid uptake ecrcekty” *Eqnnqkfu cpf Uwtfcegu C< Physiochem. and Eng. Asp. 2004, 236 (13), 91-02). The tablets were then removed from the apparatus and then dried in an oven at 60°C for a period of 24 hours. porosity measurements
[00155] Portions of a packed bed or tablet formulation were characterized by mercury porosimetry for porosity, total specific vacuum volume introduced, and pore size distribution, using a Micromeritics Autopore IV mercury porosimeter . The maximum applied pressure of mercury was 414 MPa, equivalent to a Laplace throat diameter of 0.004 μm. The data were then corrected using Pore-Comp (PAC Gane et al. “Xqkf Space Structure of Compressible Polymer Spheres and Consolidated Calcium Carbonate Paper-Coating Formulations” (Industrial cpf Engineering Chemistry Research 1996, 35 (5), 1753 - 1764) when to mercury and penetrometer effects, and also in terms of sample compression. Taking the first derivative of the cumulative intrusion curves, the pore size distributions, based on the equivalent Laplace diameter, inevitably, were revealed. including pore shielding The volume-defined average pore diameter was then calculated from the mercury intrusion fence, and FWHM was calculated from the pore size distribution curve. permeability measurements
[00156] According to Tkfiyc{ gt cL “A pgy method for measuring the liquid permeability od coated and uncoated papers and dqctfs” (Pqtfke Pulp and Paper Research Journal 2003, 18 (4), 377-381) to measure permeability, Measurement samples were prepared by placing a cuboidal piece of a tablet structure (compacted bed), having an area of 15 mm x 15 mm and a height of 10 mm inside a PTFE mold and pouring the Technovit 4000 resin. (Heraeus GmbH, Wherheim/Ts, Germany) around it, so that a sample disc having a diameter of 30 mm is then produced. The rapidly increasing viscosity of the selected curing resin results in a penetration of approximately 1 mm, locally, into the sample boundaries. This penetration depth is clearly visible due to the change in opacity at the tip of the sample and can therefore be calibrated. The open area of the porous sample, i.e. that free of resin, is evaluated in such a way that the permeable cross-sectional area can then be established. The sample disks are then placed in a dish containing the probe liquid, in order to saturate the sample vacuum network before placing it in the instrument. Hexadecane was then used in experiments with a density, p 995 kgm-3 and viscosity, i] 2.2256 kgm-1 s-1, in order to avoid any interaction with synthetic or natural binders, if present. The sample disk is then placed in a specially constructed pressure cell. The cell configuration, used for pressurized permeability experiments, is described in Rodgway et al. (Nordic Pulp and Paper Research Journal 2003, 18 (4), 377 - 381). Gas overpressure is supplied from a nitrogen bottle. The pressure cell is fixed by a Mettler Todedo AX 504 microbalance and a PC collects the balance data using specially developed software within Omya AG. A droplet catcher device was needed at the base of the cell, in order to guide the permeated liquid droplets to the exit. An important point of practical technique is that of the total chamber below the position in which the sample has to be previously wetted with the liquid, in such a way that each drop, which leaves the sample, causes a drop to fall into the interior of the disk. collection. Once these precautions have been taken, fluid continuity is assured. Absorption rate measurements
[00157] Fg ceqtfq eqo Uejqgnmqrh gV aL “OgcuwtgogpV and network modeling of liquid permeation into compacted minetai dioemu” * Lowmal of Colloid and Interface Science 2000, 227 (1), 119-131) for the measurement of “Vaza fg aduqt>« q”. aoquVtau fg IgkVq eqoraeVafq fotam tgxguVkfau eqo wo thin barrier lining around the base of the vertical ends, which originate from the basal plane, in order to reduce artifacts caused by the wetting of their external surfaces. The remainder of the outer planes were uncoated, so that free movement of air or displaced liquid during absorption is then ensured, and to minimize any interaction between the silicone and the absorbed liquid. Once the sample is lowered to contact the source of the absorbing fluid, the weight loss from the disk is continuously recorded using an automated microbalance, i.e. a Mettler Toledo AX 504 balance attached to a PC, with an accuracy of 0.1 mg, capable of 10 measurements per second, taking into account any evaporation, if present. When the recorded weight is constant, indicative of absorption-saturation, the measurement is complete. Knowing the weight of the sample, before and after the absorption measurement, allows the volume introduced per gram of sample to be calculated. (Dividing the difference in weight by the density of the liquid, the volume introduced into the sample is then obtained, and thus the volume per gram of sample).
[00158] In order to assess the print quality of the test substrates, the Testacolor TFM 157-2 laboratory scale printing device (Norbert Schlafli Maschinen, Switzerland) was employed. This device is a roll of a roll press, equipped with two flexoprint units, without intermediate drying, as shown in Fig.5. from unwinding (10), the substrate passes through 2 printing units (11, 11a), each comprising an ink feed, designated as a closed ink chamber circuit, a metering device designated as an anilox roller (nominally transferring 15.2 cm3/m2 (per unit) of ink to the substrate), a plate transport cylinder and a printing cylinder. After having passed through the second printing unit (11a), two layers of ink are on top of the test substrate surface (12), industrially standardized water-based inks such as the Sun Chemical AquaTop or NovoPrint series, of a In particular, cyan and magenta were used. The ink viscosity was then adjusted using the 4 mm DIN viscosity cup, by adding water from the spout at values between 18 seconds and 24 seconds, as commonly used in the field of the printing industry. The pH of the ink was between 8 and 9. In order to simulate the effect of mechanical stress on the substrate surface, the test substrate was then guided around four rollers (13, 13a, 14, and 14a) in a distance of 700 mm, where the substrate surface was in full contact with the rollers (14 and 14a), at a constant substrate tension (value 3 on the Schlafli control unit, on a scale of up to 10). The print speed was 100 m/minute. Depending on the drying behavior of the ink on top of a particular test substrate, staining of the substrate could then be observed, as shown in Figure 7. After the printing process, the test substrate can optionally be passed through a hot air dryer (15), so that the ink is further dried, and is then fed to a rewinder (16).
Table 1: Laboratory-scale printing conditions
[00159] In order to evaluate both printability and print quality on an industrial scale, print tests were performed on a Martin 618 Flexo folder gluer (Bobst Group SA, Switzerland). This device is a corrugated sheet press, equipped with four flexoprint units (31, 31a, 31b, and 31c), without an intermediate drying equipment and with an attached die cutting, crest forming, gluing and folding as shown in Figure 6. The sheet/test substrates are transported via a conveyor belt from a stack stacker (30) to subsequent process stages. Each printing unit (31, 31a, 31b, 31c) comprises an ink supply, designated as a closed ink chamber circuit, a dosing device designated as an anilox roller (nominally transferring an amount of ink of 10 cm3/m2 between the printing unit 31 and 31a, and an amount of ink of 8.5 cm 3 /m 2 between the printing unit 31b and 31c), a plate transport cylinder and a printing cylinder. After passing the particular printing units (31, 31a, 31b and 31c), one -(32), two-(32a), three-(32b) or four layers (32c) of ink were then transferred to the sheet, respectively. Industrially standardized water-based inks such as the Sun Chemical Aqua Top or NovoPrint series, in particular cyan, magenta, yellow and black were employed. The viscosity of the inks was then adjusted using the 4 mm DIN viscosity cup, by adding water from the spout at values between 15 seconds and 30 seconds. The pH of the inks used was between 8 and 9. The print speed ranged between 5000 and 12000 sheets/minute. The dimension of the test substrate was 1400 mm x 500 mm, which corresponds to print speeds from 40 m/minute to 100 m/minute. After having passed the last printing unit (31c), the test substrate is immediately fed into the die cutting (33), cresting (34), gluing (35 and folding (36) processing stages, in that the substrate surface comes into direct contact with the guide rollers or tools. In the case of insufficient fixation/drying of the inks, deposition and/or staining of the inks on the substrate may occur. Finally, the finished product is then fed to the distribution.
Table 2: Industrial-scale printing conditions. Stain assessment on test substrates manufactured on the laboratory-scale printing device
[00160] The following method was used to determine and quantify staining in flexographic printing of coated liners. The method can be divided into four stages, which are executed successively.1. Scanning a printed area
[00161] A stand-mounted, computer-controlled digital camera was used to digitize a statistically reasonable sample area for staining quantification. A resolution of 3456 x 2304 pixels was selected, in order to cover an area of 6.81 x 4.27 cm2. The images obtained were saved as jpeg files without data compression.2. Image preparation
[00162] A digital image usually consists of three channels or matrices, representing the colors red, green and blue, and 256 hues per color. The color channels were separated into individual images, which consist of only one matrix, but also of 256 hues using the free software Irfan View. An additional grayscale image was then calculated from the original images with Irfan View. The newly generated images were further analyzed with the free software Octave GNU.3. image analysis
[00163] The free software GNU Octave was used to analyze the newly generated images. Said software manipulates images as matrices and allows a simple manipulation of these images. An algorithm to calculate the cumulative frequency for all possible gray levels (0 to 255) has been developed, as follows: function [counts,freque] = smearing % call functionticks=0:1:255; % definition of classes or edges (grey scales) freque(:,1)=ticks; % definition of results filedirlist=dir(pwd); % look for files in working directoryfor i=3:length(dirlist)-1 % handle all files in directory img=imread(dirlist(i).name); % read the (i-2)th image from dir. helpvec=reshape(img,[],1); % transform matrix to vector help256=histc(helpvec,ticks); % count number of values help256=cumsum(help256); % cumulate the countshelp256=help256/help256(length(help256)); % calculate frequencies frequency(:,i-1)=help256; % compile results fileendsave RESULTfreque.txt "freque" "-ascii" % save results file endfunction
[00164] This algorithm is launched from a user interface (GUI Octave) and returns a text file (RESULTfreque.txt in the working directory) with the compiled results for further analysis.4. Significant results preparation
[00165] Excel was used to create a chart as shown in Fig. 8. Fig. 8 shows the cumulative distributions for the different color channels from hues 0 to 255 of the grayscale image. The average (dimensionless) frequency corresponds to the fraction of the test substrate area that is covered by a specific matrix. The best staining direction is the threshold range of 50 to 150, which is shown in Fig. 9, and which is indicated by nearly constant rows and by larger differences in the cumulative distributions. In this way, an average frequency can be calculated for this hue range.2. Examples A. flexographic printing
[00166] The following components were used to prepare the liquid coating compositions applied to the substrate, as compiled in Table 4 below. Substrate: Testliner III glued with top ply, with a basis weight (grammage) of 125 g/m2 , commercially available from Hamburger Pitten GmbH & Co., KG, Austria.Pigment 1: Omyaprime HO 40 GO (precipitated calcium carbonate), commercially available from Omya AG, Switzerland.Pigment 2: Omya Hydrocarb 60 GU (precipitated calcium carbonate) , commercially available from Omya AG, Switzerland.Pigment 3: Naturally ground calcium carbonate (d50: 230 nm, BET: 19.1 m2/g).Pigment 4: Omya Covercarb 75 GU: 71.5% (ground calcium carbonate) , commercially available from Omya AG, Switzerland Pigment 5: Naturally milled calcium carbonate (d50: 250 nm, BET: 24.8 m2/g).Binder: Litex PX 9464 (anionic styrene/butadienecarboxylated copolymer), commercially available from Synthomer Deutschland GmbH, Germany.Rheology Modifiers: St erocoll DF3x (acrylate copolymer) and Luminen 1-SC (Sodium sulfosuccinate solution), both commercially available from BASF, Germany. Table 3 shows the properties of the pigments used to produce the coating compositions characterized in Table 4.
Table 3: Pigment propertiesPigment preparation 5
[00167] Norwegian marble rocks from the region of Molde, Norway, having a diameter of 10-300 mm, were dry milled, in an autogenous manner (i.e., in the absence of grinding medium) to a fineness of 1 d50 of 42-48 μm. This material was then wet milled to a solids content of 25% by weight in tap water in a vertical friction mill of a volume of 1500 liters in a continuous mode using zirconium silicate beads of 0.3 - 0.7 mm, without any additives such as dispersing and/or grinding aids, to a fineness until the d98 was 2.05 μm and the d50 was 0.5 μm.
[0001] The product was further milled to a solids content of 20% by weight in a vertical friction mill of a volume of 1500 liters, in a continuous mode, using 0.3-0 zirconium silicate beads. .7 mm, by adding 0.40% by weight of a sodium/calcium polyacrylate dispersant having a molecular weight (Mw) of 5500 and a polydispersity of 2.7. The product obtained had a d98 of 0.69 μm and a d50 of 0.25 μm. The temperature in both grinding stages was approximately 85°C.
[00169] This suspension was then concentrated to a solids content of 50% by weight in a thermal evaporator and before evaporation, another 0.45% by weight of the sodium/calcium polyacrylate dispersant having a molecular weight (Mw) of 5500 and a polydispersity of 2.7 of dispersing agent were then added.
[00170] A fraction of this suspension having a solids content of 50% by weight was further concentrated to a solids content of 56% by weight. The pH of the two samples is 10.2 and the Brookfield viscosity is 65 mPa.s and 56 mPa.s, respectively.
[00171] The foregoing pigments were used to prepare three different liquid coating compositions (see Table 4) to demonstrate the invention.
Table 4: Coating compositions
[00172] The liquid coating compositions (prior art example, which is a topcoat formulation for white topliner, or B or D (coated compositions) were coated, once, with a curtain coating machine , PTS Munich, with an amount of 17 to 20 g/m 2 on the substrate. The solids content of the coating composition was about 60% by weight, based on the total weight of the liquid composition. The coating layer was then dried on the coating machine to a final moisture content of 4.5 to 5%.
[00173] In order for a double coated substrate to be prepared, the substrate was then curtain coated in several layers with a curtain coating machine at PTS Munich. To the precoat, an amount of about 13 g/m 2 of the liquid precoat composition C was then applied. The solids content of the liquid coating compositions was about 68%, by weight, based on the total weight. of the liquid composition. The additional topcoat layer, applied in the same sequence as the precoat, with the same curtain coating machine in PTS Munich, with an amount of 5 to 7 g/m2 of liquid coating composition B (inventive composition) (see Table 4 above), which is a typical topcoat formulation for white topcoat. The solids content of the liquid coating compositions was 60% by weight based on the total weight of the liquid composition. Both coating layers were then dried on the coating machine to a final moisture content of 4.5 to 5%.
[00174] The print quality of test substrates in flexographic printing was then evaluated by measuring optical densities. Results using the Marin 618 felxographic printing system (Bobst Group SA, Sweden) with a color volume of 37 cmW are shown in Table 5. In addition, a comparison of the gloss and print gloss values measured for the substrates of test, is shown in Table 6. Figures 8 and 9 show graphs, which illustrate the staining of a white top test liner (WTTL), on two comparative coated test substrates, and on a test substrate, comprising the coating layer according to the invention. OD sum (cyan, magenta) OD sum (cyan, magenta, yellow, black)
Table 5: Measured optical density for test substrates printed on the Martin 618 flexographic printing system (Bobst Group SA, Switzerland) with a color volume of 37 cm3/m2. Cyan OD Magenta OD
Table 5a: Measured optical density for test substrates printed on Testacolor TRM 157 2 flexo lab scale printing system, Norbert Schlafli Maschinen, Switzerland, described in Table 1. Paper Gloss Black Print Gloss Cyan Print Gloss Print Gloss magenta
Table 6: The measured gloss and print gloss for the uncalendered test substrates printed on the Martin 618 flexographic printing system (Bobst Group S.A, Switzerland) with a color volume of 37 cm3/m2.
[00175] The results show that the substrates comprising the coating composition according to the invention provide improved optical density and gloss values compared to the uncoated substrate. The optical density values obtained in flexographic printing using the substrate with a single coating reveal that the optical density on the single coated substrate, which comprises the coating according to the invention, is comparable or even better than that of the one-time coated substrate, which comprises the comparative substrate. The same is true for gloss and print gloss values. Both the optical density and the gloss of the print obtained can be further improved by pre-coating the substrate before applying the coating composition according to the invention.
[00176] Furthermore, it can be further observed from Fig. 7, in the figure to the right, that flexographic printing, which uses two colors (cyan and magenta) on the coated substrate only once, which comprises the comparative coating, leads to unacceptable staining of the printed ink, due to a slow absorption of the ink thinner (visible as gray spots at the bottom of the test print on the right (63)). In contrast, smearing of the printed ink is not observed in the flexo print placed on the coated substrate only once, which comprises the coating according to the invention (see Fig. 7, lower part of the test print on the left (53)) . The areas of the test substrates, which are designated with the reference signs (50) and (60), respectively, are printed in cyan, and the areas, which are designated with the reference signs (52) and (62), respectively, are printed in magenta, and areas (51) and (61) are a mixture of cyan and magenta, resulting in a dark violet hue.
[00177] The same applies to the coating according to the invention versus the comparative coating shown in Fig. 10, wherein the pigment which is used in the coating according to the invention is naturally ground calcium carbonate. It can be further observed from Fig. 10, in the figure on the right, that color flexographic printing, which uses two colors (cyan and magenta) on the coated substrate only once, which comprises the comparative coating, leads to unacceptable staining of the printing ink, due to a slow absorption of the ink thinner ( visible as gray spots at the bottom of the test print on the right ( 83)). In contrast, printing ink smearing is not observed in color flexo printing on the one-time coated substrate comprising the coating according to the invention (See Fig. 10-, lower part of test print on the left (73) ). The areas of the test substrates, which are designated with the reference signs (70) and (80), respectively, are printed in cyan, and the areas that are designated with the reference signs (72) and (82), respectively. , are printed in magenta, and areas (71) and (81) are a mixture of cyan and magenta, which results in a dark violet hue.
[00178] The results of the evaluation of staining on the test substrates, using the method and algorithm described above, are shown in Fig. 8 and Fig.9, which shows a section of the graphs in Fig. 8, in the shaded region from 50 to 150. It can be further seen from the graphs shown in Figs. 8 and 9, that the staining of the test substrate according to the present invention is much lower than that on the test substrates, which comprise a coating layer according to the prior art and which is comparable to the staining on an uncoated white top test coat (WTTL).B. ink jet printing
[00179] The following components were used to prepare the liquid coating compositions, applied to the substrate, as compiled in Table 8 below. Substrate: Uncoated wood-free base paper with a basis weight (grammage) of 90 g/m2 , by Stora Enso Uetersen, Germany. Pigment 6: Omyjet 5010 (carbonate and modified calcium), commercially available from Omya AG, Switzerland.Pigment 3: Precipitated calcium carbonate (d50: 230 nm, BET: 19.1m2/g).Pigment 7: Omyajet 6000 (carbonate of modified calcium), commercially available from Omya AG, Switzerland.Binder 2: CHP 104 (polyvinyl acetate), commercially available from CH Polymers OY, Finland.Binder 3: BF 04 (polyvinyl alcohol), commercially available from Chang Chung Petrochemicals, China .
[00180] Table 7 shows the properties of the pigments used for
Table 7: Pigment properties
[00181] The foregoing pigments were used to prepare three different liquid coating compositions (see Table 8) to demonstrate the invention.
Table 8: Coating Compositions
[00182] Liquid coating compositions E (prior art example), which is a typical topcoat formulation for inkjet paper, or F (composition according to the invention) were uniquely and consistently coated. a dual mode with a blade coating machine, BASF Ludwighafen, with an amount of 10 to 14 g/m2 on the substrate. The solids content of the liquid coating compositions was about 57% by weight based on the total weight of the liquid composition. The coating layer was then dried on the coating machine to a total moisture content of 4.5 to 5%.
[00183] In order to prepare a one-time coated substrate, the substrate consisted of a single layer, coated with a BASF Ludwigshafen blade coating machine, with an amount of 10 to 14 g/m2 of liquid coating composition F (composition according to the invention) (see Table 8 above), which is a typical topcoat formulation for inkjet paper. The solids content of the liquid coating compositions was about 57% by weight based on the total weight of the liquid composition. Both coating layers were then dried on the coating machine to a final moisture content of 4.5 to 5%.
[00184] The print quality of the test substrates in inkjet printing was then evaluated by measuring the volume of the optical color gamut and mottle. Results using the HP OfficeJet Pro 8000 Inkjet Printing System (Hewlett Packard, USA) are shown in Table 9. In addition, a comparison of the gloss and print gloss values measured for the test substrate, is shown in Table 10. Mottle was then measured using a VIA-Prufbau type printability tester, Verity IA Print Targent, and the color gamut was then measured using a SpectroDens spectrometer. Techkon GmbH, Germany. Mottle sum (black, blue, green) Color gamut
Table 9: Measured optical density for test substrates printed on the HP OfficeJet Pro 8000 (HP, USA)
Table 10: Measured print gloss and gloss for test uncalendered substrates printed on the HP OfficeJet Pro 8000 (HP, USA).
[00185] A mottling of inkjet printing can be observed. Mottle is an uneven print appearance, particularly on solid areas: small light and dark areas on the paper surface caused by ink. Mottle is further influenced by several parameters: for example, ink, color sequence, printing press construction, and the like. Variations in surface characteristics, such as absorbency and smoothness, play an important role with regard to mottling and are caused by the production process and the components within the paper.
[00186] With current conventional inkjet formulations, undesirable deposit effects (so-called mottling) can be observed. For example, Figure 12 shows an inkjet print run on a one-time comparative coated media. Areas of this test substrate, which are designated with reference signals (100) and (104), exhibit undesired deposition effects. In these areas, the undried ink from the previous sheet is deposited onto the present sheet through the die of the printing press. The areas designated with the reference signal (102) show good drying behavior and image quality.
[00187] In contrast, the inventive solution shown in Figure 11 does not show any deposits and presents perfect image reproduction in all areas. In Figure 11, all areas of the test substrate, which are designated with reference signals (90), (92), and (94), show perfect image reproduction.

权利要求:
Claims (31)
[0001]
1. Composition, characterized in that it comprises pigment particles, said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, a polydispersity defined in volume, expressed as the total width in half maximum height (FWHM) of 40 to 80 nm, and a defined volume mean pore diameter of 30 to 80 nm.
[0002]
2. Composition according to claim 1, characterized in that the composition is a liquid or dry coating composition.
[0003]
3. Printing medium, characterized in that it comprises a substrate having a first side and a reverse side, wherein the substrate comprises, at least on the first side, at least one permeable coating layer, formed by a composition comprising pigment particles as defined in claim 1, wherein said pigment particles, when in a compacted bed form, have a monomodal pore diameter distribution, a defined polydispersity by volume, expressed as full width at half maximum height (FWHM) from 40 to 80 nm, and a defined volume mean pore diameter of 30 to 80 nm.
[0004]
4. Printing medium according to claim 3, characterized in that the substrate is selected from paper, cardboard, container board, plastic, cellophane, textile, wood, metal, or concrete, and preferably , paper, cardboard, or cardboard for container.
[0005]
5. Printing medium according to claim 3 or 4, characterized in that the substrate comprises at least one permeable coating layer on the first side and on the reverse side.
[0006]
6. Printing medium according to any one of claims 3 to 5, characterized in that the substrate is structured by at least two sub-layers, preferably three, five or seven sub-layers.
[0007]
7. Printing medium according to any one of claims 3 to 6, characterized in that the substrate is pre-coated, preferably with precipitated calcium carbonate, modified calcium carbonate, or ground calcium carbonate, or mixtures of the same.
[0008]
8. Printing medium according to any one of claims 3 to 7, characterized in that the pigment particles are selected from calcium carbonate, plastic pigments, such as plastic pigments based on polystyrene, titanium dioxide, dolomite, calcined clay, non-calcined (hydrous) clay, bentonite, or mixtures thereof, preferably calcium carbonate, and even more preferably precipitated calcium carbonate.
[0009]
9. Printing medium according to any one of claims 3 to 8, characterized in that the pigment particles, when in the form of a compacted bed, have a polydispersity defined in volume, expressed as the total width at half height maximum (FWHM) from 45 to 75 nm, and even more preferably from 50 to 70 nm.
[0010]
10. Printing medium according to any one of claims 3 to 9, characterized in that the pigment particles, when in the form of a compacted bed, have an average pore diameter defined by volume of 35 to 75 nm, and preferably from 40 to 70 nm.
[0011]
11. Printing medium according to any one of claims 3 to 10, characterized in that the pigment particles, when in the form of a compacted bed, have a total specific vacuum volume introduced from 0.20 to 0, 50 cm3/g, preferably from 0.25 to 0.48 cm3/g, and more preferably from 0.30 to 0.55 cm3/g, and even more preferably from 0.35 at 0.40 cm 3 /g.
[0012]
Printing medium according to any one of claims 3 to 11, characterized in that the pigment particles have a specific surface area of 10 to 30 m 2 /g, and preferably 15 to 25 m 2 /g.
[0013]
Printing medium according to any one of claims 3 to 12, characterized in that the pigment particles have a weight average particle size of d50 < 300 nm, preferably 20 to 250 nm, more preferably from 50 to 240 nm, and even more preferably from 70 to 230 nm.
[0014]
Printing medium according to any one of claims 3 to 13, characterized in that the coating layer further contains a coating binder, preferably in an amount of 1 to 20% by weight, based on in the total weight of the pigment particles and preferably from 3 to 15% by weight, and even more preferably from 6 to 12% by weight.
[0015]
15. Printing medium according to any one of claims 3 to 14, characterized in that the coating binder is selected from starch, polyvinyl alcohol, styrene-butadiene latex, styrene-acrylate latex, or polyvinyl acetate, or mixtures thereof, and preferably a styrene-butadiene latex.
[0016]
Printing medium according to any one of claims 3 to 15, characterized in that the coating layer has a coating weight of from 1 to 50 g/m2, preferably from 2 to 40 g/m2, more preferably from 3 to 30 g/m2, and even more preferably from 5 to 20 g/m2.
[0017]
17. Printing medium according to any one of claims 3 to 16, characterized in that the coating layer further comprises a rheology modifier in an amount of less than 1% by weight based on the total weight of the particles of pigment.
[0018]
18. Printing medium according to any one of claims 3 to 17, characterized in that the coating layer has a permeability greater than 0.2 x 10-17 m2, and even more preferably of 0. 4 10-17 m2 to 2.5 x 10-17 m2.
[0019]
19. Printing medium according to any one of claims 3 to 18, characterized in that the printing medium is a flexographic printing medium.
[0020]
20. Method for producing a printing medium, as defined in claim 3, characterized in that it comprises the stages of: a) providing a substrate having a first side and a reverse side, and b) applying a coating composition that comprises pigment particles as defined in claim 1 and at least one coating binder on the first side of the substrate so that a permeable coating layer is formed, wherein said pigment particles, when in the form of a compacted bed, have a monomodal pore diameter distribution, a defined polydispersity in volume, expressed as the total width at a half maximum height (FWHM) of 40 to 80 nm, and a defined average pore diameter in volume of 30 to 80 no.
[0021]
21. Method according to claim 20, characterized in that the coating composition is a liquid composition and the method further comprises stage c) of drying the coating layer.
[0022]
22. Method according to claim 21, characterized in that stages b) and c) are also carried out on the reverse side of the substrate, in such a way that a printing medium is manufactured being coated on the first side and on the side reverse.
[0023]
23. Method according to claim 21 or 22, characterized in that stages b) and c) are carried out a second time, using a different composition, or the same liquid coating composition.
[0024]
24. Method according to claim 20, characterized in that the coating composition is a dry coating composition and stage b) is also carried out on the reverse side of the substrate, in such a way that a printing medium is manufactured by being coated on the first side and on the reverse side.
[0025]
25. Method according to claim 24, characterized in that stage b) is also carried out a second time, using the same or a different coating composition.
[0026]
A method according to any one of claims 21 to 23, characterized in that the liquid coating composition used to form the coating layer has a solids content of 10 to 80% by weight and a preferably from 30 to 75% by weight, more preferably from 40 to 70% by weight, and even more preferably from 45 to 65% by weight, based on the total weight of the liquid coating composition.
[0027]
A method according to any one of claims 21 to 26, characterized in that the liquid coating composition has a Brookfield viscosity in the range of 20 to 3000 mPa.s, preferably 250 to 3000 mPa.s, and even more preferably from 1000 to 2500 mPa.s.
[0028]
A method according to any one of claims 20 to 27, characterized in that the coating composition is applied via high speed coating, metering sizing press, curtain coating, spray coating, blade coating, or electrostatic coating.
[0029]
29. Use of a composition comprising pigment particles, as defined in claim 1, characterized in that it is in a printing application, wherein said pigment particles, when in the form of a compacted bed, have a distribution of monomodal pore diameter, a polydispersity defined by volume, expressed as full width at half maximum height (FWHM) of 40 to 80 nm, and an average pore diameter, defined by volume, of 30 to 80 nm.
[0030]
Use according to claim 29, characterized in that the printing application is a flexographic printing application, preferably the manufacture of a coated flexographic printing medium.
[0031]
31. Use of a printing medium as defined in any one of claims 3 to 19, characterized in that it is in a flexographic printing application, preferably wet-on-wet flexography, and even more preferred in wet-on-wet prepress or wet-on-wet postpress flexo, and even more preferred in in-line wet-on-wet postpress flexo.

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同族专利:

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公开号 | 公开日

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DK2711459T3|2016-04-18|

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SI2711459T1|2016-02-29|

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ES2564269T3|2016-03-21|

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US20160023451A1|2016-01-28|

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KR101733898B1|2017-05-08|

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RU2608415C2|2017-01-18|

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US9427999B2|2016-08-30|

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CL2015000671A1|2015-08-07|

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EP2711459B1|2016-01-13|

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AU2013320271B2|2016-01-21|

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US20150210103A1|2015-07-30|

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CA2882106A1|2014-03-27|

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US9248685B2|2016-02-02|

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ZA201502645B|2016-11-30|

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CN104662228A|2015-05-27|

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MX2015003243A|2015-06-10|

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BR112015004795A2|2017-07-04|

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AU2013320271A1|2015-03-05|

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CA2882106C|2018-05-01|

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WO2014044778A1|2014-03-27|

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EP2898146A1|2015-07-29|

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TW201428157A|2014-07-16|

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RU2015114444A|2016-11-10|

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TWI503465B|2015-10-11|

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MX347413B|2017-04-26|

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PL2711459T3|2016-07-29|

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CN104662228B|2016-08-17|

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KR20150042243A|2015-04-20|

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JP6105732B2|2017-03-29|

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NZ706649A|2017-01-27|

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JP2015529755A|2015-10-08|

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EP2711459A1|2014-03-26|

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法律状态:
2018-03-06| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2018-03-13| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2018-03-20| B06I| Publication of requirement cancelled [chapter 6.9 patent gazette]|Free format text: ANULADA A PUBLICACAO CODIGO 6.6.1 NA RPI NO 2462 DE 13/03/2018 POR TER SIDO INDEVIDA. |

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2021-06-22| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|

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2021-12-14| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2022-02-01| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 19/09/2013, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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EP12185246.1|2012-09-20|

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EP12185246.1A|EP2711459B1|2012-09-20|2012-09-20|Print medium|

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US201261704615P| true| 2012-09-24|2012-09-24|

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US61/704,615|2012-09-24|

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PCT/EP2013/069525|WO2014044778A1|2012-09-20|2013-09-19|Print medium|

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