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    • 专利摘要:
    method of altering the flake size distribution of a filler dispersion with a pretreatment agent in the production of paper, board or the like. the invention relates to a method for producing paper, board or the like comprising (i) obtaining an aqueous dispersion of mineral filler, comprising particles of first mineral filler, and having flake size distribution with original average chord length value (ii) contacting a cationic pretreatment agent capable of initiating flocculation of the filler particles in the dispersion with the particles of the first mineral filler, and forming a pretreated filler dispersion comprising flakes, which comprise the first mineral particles , (iii) combining the pretreated filler dispersion with fiber material, (iv) changing the flake size distribution of the filler dispersion with the pretreatment agent, which is a natural and/or synthetic polymer, of so that the average chord length value increases by at least 2% from the initial average chord length value. The invention also relates to a cluster comprising and at least one first mineral filler particle, and a plurality of second mineral filler particles associated with the at least one first filler particle by a pretreatment agent, which is a natural and/or synthetic polymer.
    公开号:BR112014017151B1
    申请号:R112014017151-3
    申请日:2013-01-16
    公开日:2021-08-17
    发明作者:Matti Hietaniemi；Mikko Virtanen；Jonni Ahlgren
    申请人:Kemira Oyj；
    IPC主号:
    专利说明:

    [001] The present invention relates to a method for the production of paper, cardboard or the like, and chipboard according to the preamble of the appended independent claims.
    [002] Fillers such as clay, calcium carbonate, calcium sulfate or talc are used in paper and board to reduce costs and to improve the optical properties of paper or board, such as opacity and light reflection. Fillers are added to the fiber material before the headbox of a paper or board machine. For coating pigments of coated paper or board grades, which comprise the same minerals that are used as fillers, may partly enter the paper through breakage, which is recycled back into the papermaking process. The content of fillers and coating pigments is usually measured by measuring the ash content by burning the material or paper sample at 525 °C. The base paper for uncoated fine paper and coated fine paper is made from both long and short grain and its ash content is typically 18 to 24%. The base paper for 100% long-fiber based uncoated fine paper and coated fine paper has an ash content typically 10 to 17%.
    [003] Increasing the fill content of the paper reduces the strength properties of the formed paper, as the amount of mineral material is increased and the amount of fibers in the paper is reduced. Filler particles are supposed to interfere with fiber-to-fiber bonds, and thus impair the strength of the paper. It was observed that the size of the filler particles is an important variable that influences the strength of the paper, as large filler particles do not interfere with the fiber-fiber bond as much as small filler particles. Thus, for paper strength, it would be advisable to increase the size of the individual filler particles. Large individual filler particles can, however, cause problems in other parts of the papermaking process, for example they can be more difficult to retain under high shear forces and therefore result in retention problems in the wet end phase. of the paper or card machine.
    [004] An objective of the present invention is to minimize or even eliminate the existing disadvantages in the prior art.
    [005] An objective of the present invention is to provide a simple and effective method for increasing the filler content in paper, paperboard or the like, while maintaining the strength properties and/or optical properties of the paper or paperboard produced.
    [006] An objective of the present invention is to increase the filler content of paper or cardboard in order to reduce paper manufacturing costs while maintaining the strength properties of the paper or cardboard produced.
    [007] These objectives are achieved with a method and a device that has the characteristics presented below in the characterizing parts of the independent claims.
    [008] Typical method according to the present invention for the production of paper, board or the like, comprises obtaining an aqueous dispersion of mineral filler, comprising particles of at least a first mineral filler, the filler dispersion having a distribution of flake size with an original average chord length value.- contacting a cationic pretreatment agent capable of initiating flocculation of the filler particles in the dispersion with the particles of the first mineral filler, and form a prefiller dispersion. -treated comprising flakes, comprising the first mineral particles, - combining the pretreated filler dispersion with a fiber material and - changing the flake size distribution of the filler dispersion with the pretreatment agent, which is a natural and/or synthetic polymer, so that the average chord length value increases by at least 2% from the average chord length value. the initial.
    [009] Typical agglomerate according to the present invention comprises - at least one first mineral filler particle, - a plurality of different second mineral filler particles bonded to at least one first mineral filler particle by a pretreatment agent, which is a natural and/or synthetic polymer, in which
    [0010] the weight average particle size of the first mineral filler particles is 0.5 to 4.0 µm, the weight average particle size of the second mineral filler particles is 0.5 to 2.4 µm, provided that the second mineral filler particles are smaller than the first mineral filler particles and the average strand length of the agglomerate is < 40 µm.
    [0011] The typical use of a method according to the present invention is for the production of supercalendered paper (SC), light coated paper (LWC), newsprint, fine paper, packaging board, white top linerboard or white chipboard lined up.
    [0012] It has now surprisingly been found that the filler content of paper produced can be significantly increased, while still maintaining the strength and optical properties of the final paper, by controllable pretreatment of a mineral filler dispersion comprising at least one filler mineral sometimes two or more different mineral fillers, so that the flakes formed in the mineral filler dispersion are sufficiently large, that is, the average chord length value increases with at least 2% of the chord length value initial medium. It was suddenly realized that optimizing the size of the formed filler flakes offers unexpected advantages. For example, it has been observed that the mineral filler content can be increased from 1 to 5% while maintaining acceptable paper strength. When using the present invention, the light scattering coefficient for the final paper produced is kept constant or nearly constant at the constant fill level. Light scatter values are typically in the range of ± 5%.
    [0013] In this application flocculation is understood as a contact and adhesion process in which particles of a dispersion form large-sized agglomerates. "Floculation" is used synonymously with the terms agglomeration and aggregation, and "flake" is used synonymously with the terms agglomerate and aggregate. Flake is understood herein as a cluster, comprising at least two, preferably a plurality of primary particles bonded together by electrostatic forces, the size of the cluster being larger than the size of the individual primary mineral particles. In this application, the first and second mineral filler particles are the primary particles that form the flakes.
    [0014] In this application, the "average molecular weight" value is used to describe the polymer chain length dimension. Molecular weight average values are calculated from the intrinsic viscosity results measured in a known manner in 1N NaCl at 25°C. The selected capillary is suitable for the viscosity value to be measured, and in measurements in this application an Ubbelohde capillary viscometer with constant K = 0.005228 was used. The average molecular weight is then calculated from the intrinsic viscosity results in a known way using the Mark-Houwink equation [n] = K • Ma, where [n] is the intrinsic viscosity, M the molecular weight (g/ mol), and K are given parameters in Polymer Handbook, Fourth Edition, Volume 2, Editors: J. Brandrup, EH Immergut and EA Grunke, John Wiley & Sons, Inc., USA, 1999, p. VII/11 for poly(acrylamide-co-N,N,N-trimethyl acrylate aminoethyl chloride), 70% acrylamide. Consequently, the value of parameter K is 0.0105 ml/g and the value of parameter a is 0.3. The average molecular weight range determined for the condition parameters used is 450,000 to 2,700,000 g/mol, but the same parameters are used to describe the magnitude of the molecular weight also outside this range.
    [0015] In this application, the term "cationic polymer" describes a synthetic or naturally occurring polymer, which at the prevailing pH has an overall net positive charge. This means that the polymer can also contain negative groups, as long as the net charge is positive at the pH it is used. For example, a cationic polymer may have a positive charge, in an acidic environment, where it is used, but it loses this positive charge under neutral or basic conditions. Preferably, the cationic polymer, synthetic or naturally derived, has a formal cationic net charge over the entire pH range.
    [0016] According to an embodiment of the invention, the average particle size by weight of the first mineral filler particles is 0.8 to 3.5 µm, preferably 2.0 to 3.0 µm, and the size of the second mineral filler particles is 0.6 - to 2.0 µm, preferably 0.7 to 10.8 µm, provided the second mineral filler particles are smaller than the first mineral filler particles. It has been observed that flakes, which provide good strength and retention properties, are obtained when the first mineral filler particles are larger than the second mineral filler particles.
    [0017] According to a preferred embodiment of the invention, the flake size distribution of the mineral filler dispersion is changed with the pretreatment agent so that the average chord length value increases from 2 to 100%, typically 3 to 60%, preferably 5 to 40% of the original average chord length value. In this application, the term "average chord length" describes particle size that was measured using Focused Beam Reflectance Measurement (FBRM). All flake size values in this order were measured using Focused Beam Reflectance Measurement (FBRM), the measuring range of the device being 1 to 1000 µm. FBRM apparatus used is Lasentec FBRM Model D600L by Laser Sensor Technology, Redmond, WA, USA, Serial No. 1106, and its detector is D600L-HC22-K, Serial No. 961. A more detailed description of the size measurements of flake is given in the experimental section.
    [0018] According to an embodiment of the invention, the pretreatment agent is a water-soluble synthetic polymer, having an average molecular weight (MW) in the range of 200 000 to 5 000 000 g/mol, preferably 350 000 to 4,000,000 g/mol, more preferably < 2,000,000 g/mol, even more preferably 500,000 to 1,900,000 g/mol. It has been observed that the size of the formed flakes or aggregates can be optimized by using a water-soluble synthetic polymer, preferably a synthetic cationic polymer, with a relatively low average molecular weight. In this context, soluble in water means that no sediment or solid precipitate can be observed and no phase separation and is not taking place in the aqueous polymer solution.
    [0019] Pretreatment agent is generally used as an aqueous dispersion. The pretreatment agent can be added to the mineral filler dispersion comprising at least one mineral filler. In case two or more different mineral fillers are used, the pretreatment agent can be added to the mineral filler dispersion comprising at least two different mineral fillers, or to the mineral filler dispersion comprising at least two different mineral fillers can be added to the aqueous solution pretreatment agent solution, or the pretreatment agent may be mixed simultaneously with a first mineral filler dispersion comprising first mineral filler particles and a second mineral filler dispersion comprising second mineral filler particles. Typically, the pretreatment agent is simultaneously contacted with a first mineral filler dispersion stream comprising a first mineral filler and a second mineral filler dispersion stream comprising a second mineral filler, after which the resulting dispersion of the prefiller treated is introduced to the fiber material. Thus, the pretreatment agent solution and mineral filler dispersion are mixed together and filler flakes are formed before the resulting dispersion mixture is introduced into the fiber material. This means that normally the pretreatment of the mineral filler dispersion is carried out online by mixing at least two streams of mineral filler dispersion with the pretreatment agent solution flowing just before the mineral filler dispersion. pretreated be added to the fiber material. Typically, the introduction of the pretreatment agent to the mineral filler dispersion comprising at least one mineral filler is carried out < 10 minutes, preferably < 30 seconds, more preferably < 20 seconds, before adding the pre-mineral filler dispersion. treated in the material.
    [0020] According to an embodiment of the invention, the pretreatment agent is added to the white water and the white water is circulated back to the preparation of the fiber material. White water comprising added coated break filler(s) and/or added unretained filler(s) is circulated back from the paper machine to prepare the fiber material. Thus, white water comprises filler minerals and fine fibers, which are <0.2 mm in length. According to a preferred embodiment, the pretreatment agent is contacted with the particles of at least the first mineral filler or the particles of the first and second mineral filler, i.e., with a mineral filler dispersion, in an aqueous environment which is substantially free of fibre, i.e. comprising a fibrous material which has a length exclusively of < 0.2 mm, which means that the environment does not contain fibrous material which has a length of > 0.2 mm. Thus, adsorption of the pretreatment agent to the fiber surface can be avoided and the forming filler flakes or agglomerates optimized.
    [0021] Typically, the pretreatment agent is added to the aqueous filler dispersion in an amount of at least 0.01% by weight. The dosage amount may be 0.01 to 0.5% by weight, preferably 0.02 to 0.1% by weight, calculated from the dry solids weight of the filler dispersion.
    [0022] The pretreatment agent can be a synthetic polymer, which is selected from a group consisting of polyacrylamide (PAM), glyoxalated polyacrylamide (GPAM), polyethyleneimine (PEI), polyamine, polyvinylamine (PVAm), polydiallyldimethylammonium chloride (poly-DADMAC), DADMAC-acrylamide copolymer, polyamidoamine epihalohydrin (PAE) and any of their mixtures. Polyacrylamide can be cationic, anionic or amphoteric, preferably cationic.
    [0023] Typically, the charge density of the pretreatment agent is 0.1 to 7 meq/g, preferably 0.2 to 5 meq/g, more preferably 0.5 to 2 meq/g, determined to pH 7.
    [0024] According to a preferred embodiment of the invention, the pretreatment agent is a cationic polyacrylamide having a molecular weight (MW) in the range of 200 000 to 2 000 000 g/mol. According to a preferred embodiment of the present invention, the pretreatment agent is or comprises cationic polyacrylamide having an average molecular weight (MW) in the range of 400,000 to 2,000,000 g/mol, typically 400,000 to 1,900,000 , more typically 500,000 to 1,900,000, preferably from 1,000,000 to 1,900,000 g/mol, more preferably from 1,200,000 to 1,900,000 g/mol. Cationic polyacrylamide can be produced by copolymerizing acrylamide with a cationic monomer or methacrylamide with a cationic monomer. The cationic monomer can be selected from the group consisting of methacryloyloxyethyl-trimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacrylamidepropyltrimethylammonium chloride, acrylamidopropyltrimethylammonium chloride, diallyldimethylammonium chloride, dimethylaminoethyl dimethylaminoethyl acrylate, dimethylaminoethyl acrylate, methacrylate - lacrylamide, dimethylaminopropylmethacrylamide, or a similar monomer. According to a preferred embodiment of the invention the cationic polyacrylamide is a copolymer of acrylamide or methacrylamide with methacryloyloxyethyltrimethyl ammonium chloride. Cationic polyacrylamide can also contain other monomers as long as its net charge is cationic and it has an acrylamide/methacrylamide backbone. An acrylamide or methacrylamide-based polymer can also be treated after polymerization to make it cationic, for example, using Hofmann or Mannich reactions.
    [0025] Cationic polyacrylamide can be prepared by conventional radical initiation polymerization methods. The polymerization of cationic polyacrylamide can be carried out through the use of solution polymerization in water, gel-type solution polymerization in water, aqueous dispersion polymerization, dispersion polymerization in an organic medium, or emulsion polymerization in an organic medium. The final cationic polyacrylamide product can be obtained either as an emulsion in an organic medium, aqueous dispersion, or as a solution in water, or as a dry powder or dry granules, after the following optional filtration and drying steps of polymerization. Typically cationic polyacrylamide is used as a solution, the dosage concentration of the cationic polyacrylamide being 0.01 to 0.5% by weight, preferably 0.1 to 0.3% by weight in the solution.
    [0026] The charge density of the cationic polyacrylamide is typically 2 to 30% by mol, preferably 3 to 20% by mol, more preferably 5 to 15% by mol. The relatively low charge density of cationic polyacrylamide aids in the formation of filler flakes with suitable preferred size.
    [0027] In this application, the term "natural polymer" describes a compound, which is of natural origin, but which can be used as unmodified or modified. The pretreatment agent can be a natural polymer, which is a polysaccharide, such as starch, chitosan, cellulose, or any of their cationic derivatives, preferably cationic starch. According to an embodiment of the invention, the pretreatment agent is high content cationic starch, which has a degree of substitution, DS, > 0.06, typically > 0.07, preferably > 0.1, more preferably 0.07 to 0.3, even more preferably 0.1 to 0.2. The high content cationic starch is preferably only slightly degraded or undegraded, and modified only by cationization. More preferably, the starch used is undegraded and not cross-linked and modified only by cationization. There are a number of derivatizing agents that can be used to impart a positive charge density to starch. A cationic starch may have quaternary ammonium, quaternary phosphonium, tertiary sulfonium, or other corresponding substituent(s). Particularly preferred is a cationic filler, which is derivatized to contain a quaternary ammonium ion, for example, by etherification of hydroxyl groups with a suitable etherification agent having a cationic character, such as the quaternary salt of N-(methyl chloride) 2,3-epoxypropyl)dimethylamine or N-(2,3-epoxypropyl)dibutylamine or N-(2,3-epoxypropyl)methylaniline. Suitable high content cationic starches are those of natural origin, for example potato, rice, corn, waxy corn, wheat, barley, sweet potato or tapioca starch, potato starch being preferred. Suitable starches preferably have an amylopectin content >70%, preferably >75%.
    [0028] The pretreatment agent can also be a mixture of two or more synthetic and/or natural polymers, the first and second polymer having a preferably different average molecular weight. In one embodiment, the pretreatment agent comprises a cationic polyacrylamide as described above and a second polymer, either synthetic or naturally derived, as described above. Typically, the second polymer has a lower molecular weight than the polyacrylamide used. Preferably, the average molecular weight (MW) of the second polymer is < 400,000 g/mol.
    [0029] In case the pretreatment agent comprises more than one polymer, any second or following polymer is added simultaneously with the first polymer to the aqueous filling dispersion. Preferably, the pretreatment agent is a single liquid solution comprising a first polymer selected from the group specified above and possible other second or following polymers.
    [0030] In case two different mineral fillers are used, the first mineral filler particles are different from the second mineral filler particles in the sense that the first mineral filler particles and the second mineral filler particles are of (a) size particle mean different in weight, D(50), measured with the Sedigraph method referred to in this application; (b) different chemical composition; and/or (c) the different crystal structure. Typically, the ratio of the average particle sizes of the first mineral filler particles to the second mineral filler particles is 1.05 to 2.0, preferably 1.1 to 1.6.
    [0031] Sedigraph method for measuring particle size is carried out as follows:
    Apparatus used is Sedigraph III 5120, Micromeritics Instrument Corporation, Norcross, GA, USA. Sedigraph III 5120 is used to measure the particle size distribution of pigment and powder slurries. Typical measuring range is 0.2 - 100 µm. The measurement is based on measuring the sedimentation rate of particles in a suspension by an X-ray beam. Measured sedimentation rates are converted into particle sizes using the so-called Stokes law. The total sample volume is 50 ml and 4% concentration. Solvent used is Daxad 23 by Micromeritics (sodium lignosulfonate, 0.02%).
    [0033] According to an embodiment of the invention, the first and/or second mineral filler are selected from the group consisting of ground calcium carbonate, precipitated calcium carbonate, clay, talc, gypsum, titanium dioxide, synthetic silicate , aluminum trihydrate, barium sulphate, magnesium oxide or mixtures thereof. Preferably, mineral fillers, which are used in the manufacture of paper or board, suitable for use in the present invention, and whose content is increased, are clay, soil or precipitated calcium carbonate, calcium sulfate, titanium dioxide, silicate synthetic or talc, or any mixtures thereof. The typical particle size of the mineral filler used in the invention depends on the filler quality. Thus clay has a typical mean particle diameter in the range 500 to 5000 nm, sometimes 500 to 1000 nm, calcium carbonate in the range 200 to 5000 nm, sometimes 200 to 400 nm, talc in the range of 1000 to 10,000 nm, titanium dioxide in the range 150 to 1000 nm, sometimes 150 to 350 nm, and synthetic silica in the range 100 nm to 1000, sometimes 100 to 400 nm.
    According to an embodiment of the invention, the particle size D(50) by weight of the second mineral filler is smaller than the particle size D(50) by weight of the first mineral filler. The smaller particles of the second mineral filler are bonded to the surface of the first mineral filler particles. According to an especially advantageous embodiment of the present invention, the first and second fillers are selected from the following combinations: GCC / clay and TiO2 / clay. For example, the first filler can be ground calcium carbonate and the second filler can be clay. In another embodiment, the first filler can be titanium dioxide and the second filler can be clay, in which case the optical properties of the paper can be increased with increasing titanium oxide content.
    [0035] Pretreatment agent can be added to the filler dispersion in a filler amount of the total amount of 1000 g/T, typically 10 to 1000 g/T, preferably < 300 g/T, more preferably 20 to 300 g/T, even more preferably 30 to 150 g/T of the total amount of filler. Total amount of fill here comprises both the first fill and the second fill. In case two or more different fillings are used, the total amount of filling here comprises both the first, second and any consecutive filling.
    [0036] According to an embodiment of the invention, also inorganic colloidal particles, which have an average particle size in water < 100 nm, are added to the filler dispersion, in addition to the pretreatment agent, in order to improve the retention of filler in the formed paper web. Inorganic colloidal particles are at least partly negatively charged particles whose average length in water diameter is <100 nm, preferably in the range of 1 to 100 nm. The average diameter of the inorganic colloidal particles is in the range 1 to 80 nm, preferably 1 - 50 nm, more preferably in the range 1 to 25 nm. The specific area (BET), which of course depends on the particle size, is preferably in the range from 30 to 1000 m2/g, more advantageously in the range from 100 to 1000 m2/g. Inorganic colloidal particles have anionic groups on their surface, which can be, for example, counterions of dissolved metal cations. Typically inorganic colloidal particles are selected from the group comprising colloidal silicate particles, such as synthetic silicates; silicates of the Mg and Al type; colloidal silica; and polysilicate microgel; polysilicic acid microgel and aluminum modified derivatives thereof. Synthetic silicates include, for example, fumed or alloyed silica, silica gel and synthetic metal silicates. Mg and Al silicates comprise types of expanded clay, that is, smectite, such as montmorillonite, hectorite, vermiculite, baidelite, saponite and sauconite, and their silicate alloys and derivatives.
    [0037] Pretreatment agent and inorganic colloidal particles can be added to the filler dispersion either simultaneously or sequentially in any order to the filler dispersion.
    [0038] The method according to the invention can be used for the production of supercalendered paper (SC), ultra light weight coated paper (ULWC), light weight coated paper (LWC), medium weight coated paper (MWC), heavyweight coated paper (HWC), machine-finished coated paper (MFC), uncoated wood free paper (UWF), coated wood free paper (WFC), light weight coated printing paper (LWCO), paper SC offset printing (SCO), specialty finished machine (MFS), multilayer coated paper, inkjet paper, copy paper, newsprint, packaging board, white top linerboard or white lined chipboard. The method is preferably used for the production of supercalendered paper (SC), light weight coated paper (LWC), newsprint, fine paper, packaging board, white linerboard top or white lined chipboard. Typical coated paper such as LWC comprises mechanical pulp from around 40 to 60% by weight, bleached softwood pulp from around 25 to 40% by weight and fillers and/or coating agents from around 20 to 35% by weight. Weight. SC paper comprises mechanical pulp from around 70 to 90% by weight and long fiber cellulose pulp from around 10 to 30%. Weight values Typical values for different types of paper can be: 40 to 80 g/m2 for SC, 40 to 70 g/m2 for LWC, 70 to 130 g/m2 for MWC, 50 to 70 g/m2 for MFC, 40 at 200 g/m2 for UWF, 70 to 90 g/m2 for MWC, 100 to 135 g/m2 for HWC, 40 to 200 g/m2 for WFC. Paper or cardboard can also comprise recycled fibers. According to an embodiment of the invention, the filler content of the paper or board is increased, whereby the ash content is > 34% (SC) of supercalendered paper, > 25% of uncoated wood-free paper ( UWF) and coated wood free base paper and >15% for newsprint, LWC paper and the paper and board grades, the ash content being measured by burning the material sample completely at 525 °C.
    [0039] A method for the production of paper, paperboard or the like, comprising - obtaining an aqueous dispersion comprising particles of at least a first mineral filler, the filler dispersion having an original average chord length value, - contacting the dispersion filler dispersion with a pretreatment agent capable of initiating flocculation of filler particles in the dispersion, - combining the pretreated flocculated filler dispersion with a fiber raw material, wherein the pretreatment agent comprises the cationic polyacrylamide which has an average molecular weight (MW) in the range of > 200 000 g/mol and < 2 000 000 g/mol.
    [0040] Another method for producing paper, paperboard or the like, which comprises obtaining an aqueous filler dispersion comprising particles of at least one first filler and at least one different second filler, the filler dispersion having a distribution of flake size with original average chord length value - contacting the filler dispersion with a pretreatment agent and form flakes, comprising first and second filler particles, - combine the pretreated filler dispersion with a filler material. fibers, - changing the flake size distribution of the dispersion with the pretreatment filler so that the average chord length value increases with at least 2% of the initial average chord length value.
    [0041] In one embodiment a cationic polyacrylamide having a molecular weight (MW) in the range of 200 000 to 2 000 000 g/mol can be used as a pretreatment agent for the filler particles. It has surprisingly been found that the filler content of paper or paperboard produced can be significantly increased, while maintaining the strength and optical properties of the final paper, by pretreating the filler dispersion with a pretreatment agent comprising a polyacrylamide cationic having average molecular weight (MW) > 200 000 g/mol and <2 000 000 g/mol. It was suddenly realized that the use of cationic polyacrylamide can optimize the size of the formed filler flakes and provide unexpected advantages such as increased filler content with maintained paper strength and good light scattering coefficient for the final produced paper or card. The flake size distribution of the filler dispersion can be changed with the pretreatment agent so that the average chord length value increases by at least 2%, typically from 2 to 100%, more typically 3 to 60% , preferably 5 - 40% of the original average chord length value. The aqueous filler dispersion may further comprise particles of at least one different second mineral filler whereby flakes are formed which comprise first filler particles and second filler particles when the pretreatment agent is contacted with the filler dispersion. formed.
    [0042] Polyacrylamide and possible second polymer can be added in any order to the filler dispersion. In the case where the pretreatment agent comprises a second polymer, in addition to the cationic polyacrylamide, the second polymer is typically added simultaneously with the cationic polyacrylamide to the aqueous filler dispersion. Polyacrylamide and the second polymer can be added separately but simultaneously. Preferably, the pretreatment agent is a liquid solution comprising cationic polyacrylamide and possible other polymers. Preferably, the pretreatment agent only includes polyacrylamide as active polymer, which has an effect on the formation of filler flake.
    [0043] The pretreatment agent comprising cationic polyacrylamide is preferably used as an aqueous dispersion or an aqueous solution, the dosage concentration of the cationic polyacrylamide being 0.01 to 0.5% by weight, preferably 0.1 to 0 .3% by weight in the solution. It can be added to a filler dispersion, or the filler dispersion can be added to the aqueous pretreatment agent solution, the filler dispersion comprising one or more fillers. Typically, the pretreatment agent is contacted with the filler dispersion and mixed with it and the filler flakes are formed before the filler dispersion is introduced into the fiber material. This means that normally the pretreatment of fillers is carried out online by mixing the filler dispersion stream with the pretreatment agent solution stream just before the pretreated filler is added to the fiber material. Typically, the introduction of the pretreatment agent to the filler dispersion is carried out <10 minutes, preferably <30 seconds and more preferably <20 seconds before adding the pretreated filler dispersion to the material.
    [0044] The invention is described in more detail below with reference to the attached schematic drawing, in which
    [0045] Figure 1 shows a first embodiment of the present invention, and
    [0046] Figure 2 shows a second modality.
    [0047] Figure 1 shows a first embodiment of the present invention, where thick matter is conveyed through a thick material tube 1 from previous material preparation stages (not shown) to off-machine silo 9. Once that the thick material from the off-machine silo 9 is conveyed by a primary ventilation pump 2 to a centrifugal cleaner 3 and from the centrifugal cleaner 3 following a purge unit 4. From the purge unit 4 the thick material is fed for the ventilation pump inbox 5 to the machine screen 6 and after the inbox 7.
    [0048] The filler is added to the fiber material after the air purge unit 4. A first filler is fed from a first filler box 12, and a different second filler is fed from a second filler box 12', using first and second filling pumps 13, 13'. Filling tube 14 is connected to the tube that transfers material from the air purge unit 4 to the machine screen 6. The flows of the first and second fills are combined prior to the addition of the pretreatment agent at the feed point 15, which is located between the stuffing box 12 and the stuffing tube 14 connection point and the stock material tube.
    [0049] From the headbox 7 the fiber material comprising pretreated filler is fed to the wire section 8 of the paper machine.
    [0050] It is also possible to add pretreatment agents at one or more addition points 19. Suitable addition points can be selected based on process, filler used and a pretreatment agent.
    [0051] Figure 2 shows a second mode, where thick material is conducted through thick material tube 1 from the previous stages of material preparation (not shown) to off-machine silo 9. From off-machine silo 9 the thick paper can be fed into a headbox 7 of a paper machine through a dilution tube 18 and dilution screen 11. The pretreatment agent can be added at feed points 15 or directly out of the silo machine 9 or after switching off the silo off-machine 9, but before the dilution pump 10. In this case the pre-treatment agent interacts with the filler particles coming from the white water used for material preparation or with particles of filler present in the raw material fiber, eg coated breakage.
    [0052] Alternatively, thick material can be taken from the off-machine silo 9 by a primary ventilation pump 2 to a centrifugal cleaner 3 and centrifugal cleaner 3 following an air purge unit 4. air purge 4 The thick material is fed by vent pump from headbox 5 to machine screen 6 and additionally to headbox 7. The filler is added to fiber material after air bleed unit 4. The filling is fed from the filling box 12, by the filling pump 13 through a filling tube 14, which is connected to the tube that transfers material from the air purge unit 4 to the machine screen 6. pretreatment agent can be fed to the filling at the feed point 15, which is located between the stuffing box 12 and the filling tube 14 connection point and the main material tube. It is also possible to add the pretreatment agent at one or more addition points 19. Suitable addition points can be selected based on process, filler used and a pretreatment agent.
    [0053] From the headbox 7 the fiber material comprising pretreated filler is fed to wire section 8 of the paper machine. EXPRESSION General procedure for conducting Focused Beam Reflectance Measurement (FBRM) tests
    [0054] FBRM apparatus used is Lasentec FBRM Model D600L by Technology, Redmond, WA, USA, Serial No. 1106, and its detector is D600L-HC22-K, Serial No. 961. The FBRM instrument is a flocculation analyzer using a highly focused laser beam and backscatter geometry as an operating principle. From the collected data the FBRM instrument provides chord length distribution, the average of the chord length values and the number of particles detected. The measuring range of the device has been adjusted to between 1 to 1000 µm.
    [0055] The following step-by-step procedure is used to determine the flake size: (1) at time 0 if stirring speed of 1000 rpm, a filling sample that is diluted to 1% consistency (500 ml) is poured into a DDJ dynamic drainage bottle (Papel Materials Research, Inc.),(2) at time 30 s pretreatment agent is dosed into the fill sample, and (3) at time 45 s sample flake size is measured.
    [0056] The doses of pretreatment polymers are based on solids per weight of dry matter of the filler, in the unit of g/t. The overall consistency of the filling was produced by drying in a heating chamber at a temperature between 100 to 105 °C. Example 1
    [0057] Example 1 illustrates the pretreatment of two fillers with a pretreatment agent.
    [0058] Fill sample is treated as a slurry with a desired solids content. Filler sample comprises 50% ground calcium carbonate, GCC, under the trade name Hydrocarb 65, having average particle size D(50) 1.98 µm measured with Sedigraph method as described, and 50% clay, under the trade name Intramax 60, having an average particle size D(50) 1.98 µm measured with Sedigraph method as described. Sample fill portions are based on dry solids content. Fill sample is obtained by diluting with tap water.
    [0059] Two pretreatment agents are tested. First pretreatment agent is denoted as pretreatment agent A, which is cationic polyacrylamide with 10 mol% filler, and molecular weight of 1,400,000 g/mol. Second pretreatment agent is denoted pretreatment agent B, which comprises a) 50% by weight of copolymer of polyacrylamide and poly-DADMAC, with 30% by mole charge and having a molecular weight of 5,000,000 g/ mol; and b) 50% by weight of poly-DADMAC with a molecular weight of 200,000 g/mol. Doses of pretreatment polymers are based on solids per weight of dry matter of the filler, the unit g/T. Full filling consistency is produced by drying in a heating chamber at a temperature between 100 to 105 °C. The pretreatment agent is added to the filler sample as a dilute aqueous paste and mixed with a magnetic stirrer.
    [0060] Average chord length before and after pretreatment is measured using FBRM apparatus and procedure described above. The results obtained for the average chord length, before and after pretreatment are presented in Table 1. Table 1 Average chord length and increase in average chord length.

    [0061] Example 1 shows that mean chord length increases as a function of pretreatment agent A and B. Example 2
    [0062] Example 2 illustrates the pretreatment of a filler with a pretreatment agent.
    [0063] Filler sample comprises titanium dioxide. The titanium dioxide particle size D(50) is 0.40 µm, measured by the Sedigrap method using Sedigraph SED5100 and measuring the dispersed particles of a water solution with 0.2% Daxad 23 as dispersant. The same A and B pretreatment agents as in Example 1 are used.
    [0064] Average fill chord length before and after pretreatment is measured using apparatus and FBRM procedure described above. The results obtained before and after pretreatment are shown in Table 2.Table 2 Average chord length of untreated and pretreated TiO2 and increase in size of pretreated TiO2 particles.

    [0065] This example shows that the average titanium dioxide filler cord length increases when treated with pretreatment agent A or B. Example 3
    [0066] Example 3 illustrates the pretreatment of a filler with different pretreatment agents.
    [0067] Sample fill comprises precipitated calcium carbonate (PCC), which is in scalenohedral form. The PCC D(50) particle size is 2.2 µm, measured by the Sedigrap method using Sedigraph SED5100 and measuring the dispersed particles of a water solution with 0.2% Daxad 23 as dispersant.
    [0068] Pretreatment agents A and C are used. Pretreatment agent A is the same as described in Example 1. Pretreatment agent C is a cationic polyacrylamide, with a 10% mole charge and a molecular weight of 800,000 g/mol.
    [0069] Average chord length of the fill before and after pretreatment are measured using FBRM apparatus and procedure described above. The results obtained before and after pretreatment are shown in Table 3. Table 3 Average chord length, average chord length increase and D(90) average chord length results obtained in Example 3.

    [0070] The results in Table 3 show that the average chord length adequately increases as a function of pretreatment agent A and C dosing. String length value D(90) is relatively constant and remains in the acceptable range with pretreatment agents A and C. String length value D(90) refers to a chord length value, 90% of sample particles having a chord length value less than this value. Example 4
    [0071] Example 4 illustrates how the pretreated filler acts as a filler in papermaking.
    [0072] The fiber material comprises thermal mechanical pulp from a paper mill, and is diluted with tap water at 0.5% consistency.
    [0073] Ground calcium carbonate, GCC, under the trade name Hydrocarb 65, having the average particle size D(50) of 1.78 µm measured with the Sedigraph method, as described, and clay under the trade name Intramax 60 with Average D(50) particle size of 1.98 µm measured with Sedigraph method as described are used in the experiments. GCC and clay are mixed as a 50/50 ratio based on dry solids content. The filling is treated as a slurry.
    [0074] Filler dispersion is pretreated with pretreatment agent A as described in Example 1. Two doses are tested, 35 g/t, or 70 g/t, given as solids, and calculated with based on the solids content of the dry fill dispersion. Pretreatment agent is added to the filling dispersion as a dilute aqueous slurry and mixed with a magnetic stirrer.
    [0075] Pretreated filler dispersion is added to the fiber sample 20 s before sheet formation to achieve desired sheet filler content. Retention aid, cationic polyacrylamide Fennopol K3400R, with approx. 1 meq/g and molecular weight 6,400,000 g/mol is added to the sample 10 s before manual sheet formation.
    [0076] Hand sheets are prepared with Rapid-Kothen hand sheet former to ISO 5269-2:2004. Target weight for manual sheets is 80 g/m2.
    [0077] Tensile strength and light scattering values are determined for the handsheet according to ISO 1924-2:2008 and ISO 9416:2009 standards. The measured values are shown in Table 4.Table 4 Fill content, tensile strength and light scattering values for the formed manual sheets.
    Example 5
    [0078] Example 5 illustrates how the pretreated filler acts as a filler in papermaking.
    [0079] Example 5 is conducted at different times as in Example 4 and different fiber material is used. The fiber material comprises thermal mechanical pulp from a paper mill, and is diluted with tap water at 0.5% consistency.
    [0080] Ground calcium carbonate, GCC, under the trade name Hydrocarb 65 having an average D(50) particle size of 1.78 µm measured with the Sedigraph Method as described, and clay under the trade name Intramax 60 with size D(50) particle media of 1.98 µm measured with the Sedigraph Method as described are used in the experiments. GCC and clay are mixed as a 50/50 ratio based on dry solids content. The filling is treated as a slurry.
    [0081] Filler dispersion is pretreated with pretreatment agent B as described in Example 1. Two doses are tested, 90 g/t, or 240 g/t, given as solids, and calculated with based on the solids content of the dry fill dispersion. Pretreatment agent is added to the filling dispersion as a dilute aqueous slurry and mixed with a magnetic stirrer.
    [0082] Pretreated filler dispersion is added to the fiber sample 20 s before sheet formation to achieve desired sheet filler content. Retention aid, cationic polyacrylamide Fennopol K3400R, with approx. 1 meq/g and molecular weight 6,400,000 g/mol is added to the sample 10 s before manual sheet formation.
    [0083] Hand sheets are prepared with Rapid-Kothen hand sheet former to ISO 5269-2:2004. Target weight for manual sheets is 80 g/m2.
    [0084] Tensile strength and light scattering values are determined for the handsheet according to ISO 1924-2:2008 and ISO 9416:2009 standards. The measured values are shown in Table 5.Table 5 Fill content, tensile index and light scattering for the formed manual sheets.

    [0085] These examples 4 and 5 show that, with pretreated fillers, it is possible to have higher tensile strength and light scattering properties for paper.
    [0086] Example 6
    [0087] Example 6 illustrates how pretreated TiO2 acts as a filler in papermaking.
    [0088] Fiber material comprising kraft pulp from a paper mill is used in the experiment, and is diluted with tap water to 0.5% consistency. The filler is titanium dioxide, and it is treated as a slurry, the amount of TiO2 filler in the suspension being 1.6% by weight.
    [0089] Filler dispersion is pretreated with pretreatment agent A or pretreatment agent B, described in Example 1. Three doses, 75 g/t, 150 g/t and 300 g/t, are tested for both pretreatment agents. Doses are administered as solids, and calculated based on the solids content of the dry-fill dispersion. Pretreatment agent is added to the filling dispersion as a dilute aqueous slurry and mixed with a magnetic stirrer.
    [0090] Pretreated filler dispersion is added to the fiber sample 20 s before sheet formation to achieve desired sheet filler content. Retention aid, cationic polyacrylamide, with charge 1 meq/g and molecular weight 6,400,000 g/mol, is added to the sample 10 s before manual sheet formation.
    [0091] Hand sheets are prepared with Rapid-Kothen hand sheet former to ISO 5269-2:2004. Target weight for manual sheets is 80 g/m2.
    [0092] Light scattering values and ash content are determined for the handsheet according to ISO 9416:2009 and ISO 1762:2001 standards. The measured values are shown in Table 6.Table 6 Ash content and light scattering results for formed manual sheets.

    [0093] Example 6 shows that with pre-treated fillers, it is possible to have the high ash content in the paper, maintaining or improving its dispersion properties.
    [0094] Even though the invention has been described with reference to what currently appear to be the most practical and preferred embodiments, it is recognized that the invention is not to be limited to the embodiments described above, but the invention is intended to cover as well different modifications and equivalent technical solutions within the scope of the included claims.
    权利要求:
    Claims (15)
    [0001]
    1. A method of changing the flake size distribution of a filler dispersion with a pretreatment agent in the production of paper, paperboard or the like, comprising obtaining an aqueous mineral filler dispersion comprising particles of at least one first mineral filler, the filler dispersion having a flake size distribution with an original average chord length value, - placing a cationic pretreatment agent, which initiates flocculation of the filler particles in the dispersion, in contact with the particles of the first mineral filler, and form a pretreated filler dispersion comprising flakes, which comprises the first mineral particles, - combine the pretreated filler dispersion with a fiber material, characterized by the fact that - the pretreated treatment is a water-soluble synthetic polymer having an average molecular weight (MW) <2,000,000 g/mol and selected from a group consisting of poly cationic acrylamide (PAM), glyoxalated polyacrylamide (GPAM), polyethyleneimine (PEI), polyamine, polyvinylamine (PVAM), polydiallyldimethylammonium chloride (poly-DADMAC), DADMAC-acrylamide copolymer, epihalohydrin polyamidoamine (PAE) and any of their mixtures ,- the charge density of the pretreatment agent is 0.1 to 7 meq/g, determined at pH 7, where,- the pretreatment agent is used as a single liquid solution comprising the cationic polymer water-soluble synthetic, and optionally other second or following polymers, - the pretreatment agent is added to the aqueous mineral filler dispersion in an amount of 0.01 to 0.5% by weight, calculated from the weight of dry solids of the filler dispersion, whereby the flake size distribution of the filler dispersion is changed with the pretreatment agent, so that the average chord length value increases with 5 to 40% of the value. of the initial average chord length.
    [0002]
    2. Method according to claim 1, characterized in that the aqueous filler dispersion further comprises particles of at least one different second mineral filler, and which forms flakes, comprising first mineral filler particles and second mineral filler particles .
    [0003]
    3. Method according to claim 1, characterized in that the pre-flocculation agent comprises only cationic polymers, preferably cationic synthetic polymers.
    [0004]
    4. Method according to claim 1, characterized in that the pretreatment agent is a water-soluble synthetic polymer, having an average molecular weight (PM) in the range of 500,000 to 1,900,000 g/mol.
    [0005]
    5. Method according to any one of claims 1 to 4, characterized in that the charge density of the pretreatment agent is 0.2 to 5 meq/g, more preferably 0.5 to 2 meq/g, determined at pH 7.
    [0006]
    6. Method according to claim 1, characterized in that the pretreatment agent is a cationic polyacrylamide having an average molecular weight (PM) in the range of 200 000 to 2 000 000 g/mol, typically 400 000 to 1 900,000, more typically 500,000 to 1,900,000, preferably 1,000,000 to 1,900,000 g/mol, more preferably 1,200,000 to 1,900,000 g/mol, and the charge density of the cationic polyacrylamide is from 2 to 30% by mol, preferably 3 to 20% by mol, more preferably 5 to 15% by mol.
    [0007]
    7. Method according to claim 1, characterized in that the pretreatment agent is a mixture of two or more synthetic polymers, the first and second polymer having a preferably different average molecular weight, preferably the pretreatment agent. The treatment comprises the cationic polyacrylamide, and a second polymer having a molecular weight lower than that of the cationic polyacrylamide, preferably <400,000 g/mol.
    [0008]
    8. Method according to claim 2, characterized in that the first filler particles and the second filler particles have (a) different average particle size, D(50), (b) different chemical composition and/or ( c) the different crystal structure, and preferably the ratio between the average particle size of the first mineral filler particles and the second mineral filler particles is from 1.05 to 2.0, preferably 1.1 to 1.6 .
    [0009]
    Method according to claim 1 or 2, characterized by selecting the first mineral filler and/or the second mineral filler from a group comprising ground calcium carbonate, precipitated calcium carbonate, clay, talc, gypsum, dioxide titanium, synthetic silicate, aluminum trihydrate, barium sulfate and magnesium oxide, preferably select the first and second mineral filler from the following combinations: GCC / clay and TiO2/clay.
    [0010]
    A method according to any one of claims 1 to 9, characterized by adding the pretreatment agent to the mineral filler dispersion in an amount of 1000 g/t of total amount filler, preferably < 300 g/t of full amount filling, more preferably 20 to 300 g/t full amount filling, even more preferably 30 to 150 g/t full amount filling.
    [0011]
    A method according to any one of claims 1 to 10, characterized by simultaneously contacting the pretreatment agent with a first dispersion stream comprising the first mineral filler and a second dispersion stream comprising a second filler mineral, after which the resulting pretreated filler dispersion is introduced into the fiber material.
    [0012]
    The method of claim 1, characterized by adding the pretreatment agent to the white water, and circulating the white water back to preparing the fiber material.
    [0013]
    The method of claim 1, characterized by placing the pretreatment agent in contact with the particles of the first and second mineral filler, in an environment that is substantially fiber-free, i.e. comprising a fibrous material which has a length of only <0.2 mm.
    [0014]
    A method according to claim 1, characterized by the addition of colloidal inorganic particles having an average particle size in water of <100 nm to the mineral filler dispersion in addition to the pretreatment agent, preferably inorganic colloidal particles are at least partially negatively charged particles, have a maximum average diameter in water in the range 1 to 100 nm, typically 1 to 80 nm, preferably 1 to 50 nm, more preferably in the range 1 to 25 nm , and preferably selecting the inorganic colloidal particles from the group comprising colloidal silicate particles, such as synthetic silicates; silicates of the Mg and Al type; colloidal silica, polysilicate microgel, polysilicic acid microgel and aluminum modified derivatives thereof.
    [0015]
    15. Use of a method as defined in any one of claims 1 to 14, characterized in that it is intended for the production of supercalendered paper (SC), light weight coated paper (LWC), newsprint, fine paper, paper- cardboard, white top linerboard or white lined chipboard.
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    同族专利:
    公开号 | 公开日
    CA2861717A1|2013-07-25|
    CN104053836A|2014-09-17|
    BR112014017151A2|2017-06-13|
    US20140360691A1|2014-12-11|
    CN104053836B|2016-10-26|
    PT2804976T|2016-07-07|
    CA2861717C|2019-12-17|
    KR20140116388A|2014-10-02|
    US9080288B2|2015-07-14|
    BR112014017151A8|2017-07-04|
    WO2013107933A1|2013-07-25|
    EP2804976B1|2016-03-30|
    EP2804976A1|2014-11-26|
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    法律状态:
    2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-08-27| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-06-01| B350| Update of information on the portal [chapter 15.35 patent gazette]|
    2021-06-29| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-08-17| 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 16/01/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US201261586881P| true| 2012-01-16|2012-01-16|
    US201261586885P| true| 2012-01-16|2012-01-16|
    FI20125050A|FI126155B|2012-01-16|2012-01-16|Procedure for the manufacture of paper, paperboard or the like|
    FI20125049A|FI125929B|2012-01-16|2012-01-16|A process for making paper, cardboard or the like|
    FI20125049|2012-01-16|
    US61/586,881|2012-01-16|
    FI20125050|2012-01-16|
    US61/586,885|2012-01-16|
    PCT/FI2013/050043|WO2013107933A1|2012-01-16|2013-01-16|Method for producing paper, board or the like and agglomerate|
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