HYDROPHOBIC PAPER OR CARDBOARD INCLUDING SELF-ASSEMBLED CELLULOSE FIBERS AND SILICON OXIDE NANOPARTI

专利摘要:
hydrophobic paper or cardboard with self-assembled nanoparticles and method for its production. The present invention relates to a hydrophobic paper or cardboard that has self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds directly bonded to the cellulose fibers of at least one of its surfaces, with a cobb value of 8 to 25 g/m² and water contact angles from 100 to 140 degrees, useful as food packaging. the hydrophobic paper or cardboard is printable, recyclable, and exhibits greater adhesion in areas that require binding of the paper or cardboard.
公开号:BR112014025470B1
申请号:R112014025470-2
申请日:2013-04-12
公开日:2021-06-29
发明作者:Néstor Luna Marroquín；Orlando Severiano Pérez；Joel Gutiérrez Antonio；Rodrigo Pámanes Bringas；Gregorio José De Haene Rosique；Julio Gómez Cordón
申请人:Sigma Alimentos, S.A. De C.V.；
IPC主号:

专利说明:

TECHNICAL FIELD OF THE INVENTION
[001] The present invention relates to coating materials; more specifically to a method for producing a hydrophobic paper or cardboard with self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds directly bonded to the cellulose fibers of the paper or cardboard. BACKGROUND OF THE INVENTION
[002] Currently, there is a large amount of food products that need to be packaged or packaged for transport when using paper or cardboard, however, due to food conservation measures, it is necessary to keep them in storage chambers. refrigeration inside their packaging. Humidity and temperature conditions under refrigeration can lead to a collapse of these packaging materials, causing a decrease in stored products, or an over specification of the cardboard to obtain the required strength, with a consequent increase in costs.
[003] In order to prevent the deterioration of the packaging material of both paper and cardboard by conditions of high humidity, several chemical compositions were studied to apply coatings that prevent the passage of moisture through the fibers of the paper or cardboard, thereby enlarging its shelf life, increasing the protection of food packaging and reducing the costs that can result from the failure of the packaging's mechanical strength. Some types of coatings such as resins, polymers, copolymers, organic and inorganic compounds are usually used on paper and cardboard; however, these do not have high moisture resistance values.
[004] The use of nanoparticles for this application represents a great economic advantage for these packages, since the interaction between the cellulose network and the coating nanoparticles can increase thanks to the incorporation of various functional groups on the nanoparticles, resulting in improvement hydrophobic properties due to chemical interactions between them and the organic matrix. Usually, inorganic particles, as in the case of silicon oxide, have a surface that has a lower compatibility with organic compounds both polymeric of the polyolefin type and ionic ones of the amide or amine type, paper fibers or other biopolymers. In order to obtain greater compatibility, the surface of the nanoparticles needs to react by different methods, for example, by self-assembly with products that contain groups that, when reacting, can be more compatible with the polymers and allow better hydrophobic properties. In other words, through chemical modification, functional groups are added to the surface of the nanoparticles to allow better incorporation or compatibility with organic products such as polymers or other material matrices such as paper.
[005] This type of nanoparticles is proposed in the Spanish patent la ES2354545 A1, which suggests the use of functionalized nanomaterials in the production of nanocompounds, to obtain different functional properties.
[006] The following are summaries and references of granted patents, patent applications and scientific publications considered in the analysis of the prior art related to hydrophobic coatings for use on paper and cardboard.
[007] In document US7943234 called "Nanotextured su per or ultra hydrophobic coatings" a superhydrophobic or ultrahydrophobic coating composition is described that includes a polymer that can be a homopolymer or copolymer of polyalkylene, polyacrylate, methyl acrylate , polyester, polyamide, polyurethane, polyvinyl arylene, polyvinyl ester, polyvinyl arylene/alkylene copolymer, polyalkylene oxide, or combinations thereof with particles having an average size of 1 nm to 25 microns, in such a manner as to provide a water contact angle between about 120° and 150° or more. In particular, the particle is silica, which has been previously treated with a silane.
[008] The patent US7927458 called "Paper articles exhibiting water resistance and method for making same" refers to a procedure for the preparation of paper and glued board that incorporates in the process a composition comprising one or more hydrophobic polymers in which the polymers hydrophobics, the amount of such polymers and the weight ratio of starch and such polymer in the composition are selected such that paper and cardboard exhibits a Cobb value equal to or less than 25 g/m2 and a sized paper or cardboard formed by the process.
[009] The document US7229678 called "Barrier laminate structure for packaging beverages" describes a laminated packaging material, which comprises a first outer layer of a low density polyethylene polymer, a cardboard substrate, a first layer of laminated inner coating of nylon with a resin bonding ply, an extrusion blown ply comprising a first ply of low density polyethylene polymer, a plying ply, a first EVOH inner ply, a second plying ply, a second inner ply of EVOH, a third bonding layer and a second inner layer of low density polyethylene polymer, and an innermost layer in contact with the low density polyethylene product.
[0010] The document US6949167 called "Tissue products having uniformly deposited hydrophobic additives and controlled wettability" describes products that contain a hydrophobic additive, such as a polysiloxane. Furthermore, paper products are additionally treated with a wetting agent.
[0011] The patent US6830657 called "Hydrophobic cationic dispersions stabilized by low molecular weight maleimide copolymers, for paper sizing" refers to a method for obtaining an aqueous dispersion of hydrophobic polymers dispersed in the form of particles with an average diameter of less than 100 nm stabilized only with a macromolecular surfactant based on a low molecular weight styrene imide maleic anhydride copolymer. It also refers to the use of said dispersion for the treatment of paper.
[0012] The document US6187143 called "Process for the manufacture of hydrophobic paper or hydrophobic board, and a sizing composition" refers to a procedure for the manufacture of hydrophobic paper or cardboard by gluing rosin resin, a complex of organic agent which is used together with rosin resin. It also refers to a sizing composition after application of the hydrophobic additive to one or more surfaces of the base sheet. The wetting agent improves the wetting properties of the base sheet.
[0013] Patent US5624471 which is entitled "Waterproof paper backed coated abrasives" describes a waterproof coated abrasive paper made in a gluing machine which comprises a radiation curable binder that is hydrophobic when it polymerizes.
[0014] In document US4268069 entitled "Paper coated with a microcapsular coating composition containing a hydrophobic silica" a coating composition comprising an oil containing microcapsules dispersed in a continuous aqueous phase, which also contains phase particles is described. finely divided silica and a binder for said microcapsules and said silica particles. The silica particles were treated with an organic material such as an organic silicon compound to impart a hydrophobic surface to the particles. The coating composition has utility in the manufacture of paper coated with microcapsules. Such paper is characterized by a substantial reduction in defects when used in photocopying apparatus which utilize a pressure contact line to assist in the transfer of the powder image from a belt of photoreceptors to the paper.
[0015] Patent application US20110008585 entitled "Water resistant corrugated paperboard and method of preparing the same" describes a method for preparing water resistant corrugated board which is composed of a corrugated medium treated with a hydrophobic agent in both the sides and a liner treated with a hydrophobic agent on at least one side of the surface. The liner and corrugated medium are adhered by an adhesive prepared with a starch carrier, raw starch, borax, a hydrophobic resin, an additive to improve penetration, and water. The starch vehicle is composed of cooked and raw starch. The lining and corrugated medium are treated with the hydrophobic agent before being bonded. Hydrophobic resins include resorcinol-formaldehyde resins, and urea-formaldehyde resins.
[0016] Patent application US20110081509A1 entitled "De gradable heat insulation container" describes a container that includes a container body made of paper, a waterproofing cap and a foam cap. The container body has an outer surface and an inner surface. The waterproofing cover is coated on the inner surface. The waterproofing layer is mainly composed of powdered talc, carbonate resin, and calcium. The foam cover is disposed over at least a part of the outer surface. The foam cover is made up of reinforcements and a thermo-expandable powder. The binder is selected from the group consisting of polyvinyl acetate resin, ethylene-vinyl acetate resin, polyacrylic acid resin, and a mixture thereof. The thermo-expandable powder is formed by a plurality of thermo-expandable container microcapsules, each of which consists of a thermoplastic polymer shell and a low-boiling solvent lined with the thermoplastic polymer shell.
[0017] Patent application US20110033663 entitled "Superhydrophobic and superhydrophilic materials, surfaces and methods" describes a method of general application that does not require more than one step, which facilitates the preparation of superhydrophobic or superhydrophobic surfaces large area on a variety of substrates such as glass, metal, plastic, paper, wood, concrete and masonry. The technique involves free radical polymerization of common acrylic or styrenic monomers in the presence of porogenic solvents in a mold or on a free surface.
[0018] Patent application US20100233468 which is entitled "Bio degradable nano-composition for application of protective coatings onto natural materials" refers to a method for manufacturing a biodegradable composition that contains cellulose nanoparticles to form a protective coating on the natural materials. One of its goals is to provide a composition to form a protective coating over a natural biodegradable material that gives the material water resistance and grease resistance. Another objective is to provide a composition to form a protective layer in biodegradable natural materials that is based on the use of cellulose nanoparticles and which protects these materials against swelling, deformation and mechanical damage during contact with water, other aqueous liquids or greasy.
[0019] Patent application US20100311889 entitled "Method for manufacturing a slip coating, using an acrylic thickener with a branched hydrophobic chain, and the obtained slip" consists of a method for manufacturing a coated paper sheet containing a mineral material, which uses, as an agent to thicken the sheet, a water-soluble polymer comprising at least one anionic monomer unsaturated with ethylene and at least one oxyalkyl monomer unsaturated with ethylene ending in a hydrophobic alkyl, alkaryl, arylalkyl, aryl, saturated or unsaturated chain, branched with 14 to 21 carbon atoms and two branches, each of which has at least six carbon atoms. The polymer is added to the sheet either directly or during an earlier step when the mineral material is crushed, dispersed or concentrated in water, which may or may not be followed by a drying step. In this way, the water retention of the slip is improved, which contributes to better printability of the sheet-coated paper.
[0020] Document US20080188154 entitled "Film laminate" describes a laminate that includes at least one layer of an environmentally degradable film, for example, a polylactide ("PLA") made of an easily available annually renewable polymer of resources such as the corn. A second layer can be a substrate made of, for example, paper, woven or non-woven fabric, or metallic foil. The environmentally degradable film and substrate are adhered together by, for example, extruded polymeric compounds or adhesives such as water-based, hot-melt, solvent-free or solvent-free adhesives. Adhesive selection depends on the type of substrate to be laminated with the environmentally degradable film and the desired properties of the resulting laminated composite structure (ie, "laminate"). The first layer is coated with a liquid polymer, a dispersion of nanoparticles, a metallic deposition or a silicone oxide deposition such that the gas permeability of the first layer is reduced. The laminates of said film find use, for example, in canisters, covers, labels and form printing, commercial publications and in the digital printing industry.
[0021] In patent application US20080265222A1 entitled "Cellulose-Containing Filling Material for Paper, Tissue, or Cardboard Products, Method for Production Thereof, Paper, Tissue, or Carboard Product Containing Such to Filling Material, or Dry Mix Used Therefor " the surface modification of cellulose fibers with the application of nanoparticles to produce packaging paper and cardboard is explained. With advantage in product production and recycling. Furthermore, with different advantages, it acts as a moisture repellant, whiteness and shine to paper and cardboard, biocide, antistatic agent, and flame retardant. Cellulose is nanodispersed and in combination with other components such as binders, polyvinyl sheets, flocculants, nanoparticle systems (not mentioned), polymers, anti-slip additives, a pigment fixing additive, whiteners, foam suppressants or preservatives.
[0022] Patent application US20080113188 entitled "Hydrophobic organic-inorganic hybrid silane coatings" describes a hydrophobic coating that can be formed from a solution that includes, for example, organically modified silicates mixed with coupling agents. Specifically, a sol-gel solution can be formed (e.g., at room temperature) which includes a plurality of alkoxy silane precursors that contain at least one alkoxy glycidoxy silane precursor. The solgel solution can be a mixed sol-gel solution formed by including a first mixed solution with a second solution. The first solution can include one or more alkoxy silane precursors, and the second solution can include at least one alkoxy glycidoxy silane precursor. A coupling agent can be added and reacted with the sol-gel solution (mixed) forming the coating solution, which can be applied over a substrate that needs to be protected against corrosion or biological and/or chemical agents.
[0023] In patent application US20080041542 entitled "Cellu lose composites comprising hydrophobic particles and their use in paper products" polymeric composite films prepared by solvent deposition of a suspension of quantum dots (QDs) in a solution of triacetate are proposed. cellulose (CTA). The films were robust and had the optical properties of quantum dots. Transmission Electron Microscopy (TEM) images of the films revealed that the quantum dots dispersed well within the CTA film matrix. Selective alkaline hydrolysis of QD/CTA films in 0.1 N NaOH for 24 hours resulted in the conversion of the CTA surface to regenerated cellulose. The optical properties of the films were tested both before and after the hydrolysis reaction using fluorescence spectroscopy, and were generally unchanged. The cellulose surfaces of the alkaline treated films allow the surface incorporation of the films into the paper sheets.
[0024] In patent application US20030211050 entitled "Compositions comprising anionic functionalized polyorganosiloxanes for hydrophobically modifying surfaces and enhancing delivery of active agents to surfaces treated therewith" compositions and methods are described for treating and modifying surfaces and for improving the administration of agents active to surfaces treated with the same, wherein the compositions comprise siloxane polymers functionalized with spare fractions that comprise two or more anionic groups, at least one anionic group, which may be a carboxy group. When applied to a suitable surface, the present composition forms a substantially hydrophobic functionalized anionic siloxane polymer layer on the treated surface.
[0025] Patent application US20030012897 entitled "Liquid resistant paperboard tube, and method and apparatus for making same" refers to a cardboard tube that becomes resistant to liquids by partially or totally coating the tube with submicron-sized particles of material inorganic which is treated to be hydrophobic and/or oleophobic. The particles can be applied directly to the cardboard, becoming lodged in the superficial pores in such a way that the particles adhere to the cardboard. Alternatively, a thin layer of a tacky binder or adhesive can be applied first to the board and then the particles can be applied in such a way that they adhere to the binder. Conveniently, the particles have a large surface area per gram; in one embodiment, for example, the silica particles that are employed have a surface area of about 90 to 130 m 2 /g. As a result, the particles create a surface on the cardboard that is highly liquid-repellent.
[0026] In patent application US20030109617 which is entitled "Method for pretreatment of filler, modified filler with a hydrophobic polymer and use of the hydrophobic polymer" is described a modified filler used in the manufacture of paper or similar, in the preparation of filler material and its use. The modified filler comprises a known filler such as, for example, calcium carbonate, kaolin, talc, titanium dioxide, sodium silicate and aluminum trihydrate or mixtures thereof, and a hydrophobic polymer made from polymerizable monomers, which it is added to the filler as a polymer dispersion or polymer solution.
[0027] In patent application US20020069989 which is entitled "Bonding of paper using latex-dispersions of copolymers made of hydrophobic monomers/polymers of styrene/maleic anhydride type of low molecular mass" latex dispersions used in formulations of a binder for paper, which make it possible to obtain acceptable COBB values, including with printing and writing papers or wrapping papers obtained from pulps of recycled material or mechanically discolored pulps.
[0028] Patent application US20020032254 entitled "Hydrophobic polymer dispersion and process for the preparation thereof" refers to a hydrophobic polymer dispersion and a solventless process for the preparation thereof. According to the invention, the dispersion contains starch ester, together with dispersion additives known as such. According to the process, the polymer is first mixed with a plasticizer to obtain a mixture of plasticized polymer. The plasticized polymer blend is then mixed with dispersion additives and water at an elevated temperature to form a dispersion. Plasticizing the polymer and dispersing the mixture in water can be carried out in an extruder. The obtained dispersion is homogenized in order to improve its stability. The dispersion obtained by the invention can be used for coating paper or cardboard, as a base or component in paint or in label adhesives, and is also suitable for the production of deposited films and as a binder in materials based on cellulose fibers as well as for medicinal coating preparations.
[0029] Patent application W02011059398Al entitled "Strong nanopaper" refers to nanopaper comprising a clay and microfibrillated cellulose nanofibers in which the MFC nanofibers and clay layers are oriented substantially parallel to the surface of the paper. The invention also relates to a method for the manufacture of nanopaper and its use.
[0030] The patent application W02009091406Al with the title "Coated paperboard with enhanced compressibility" mentions a coated paperboard with a better compressibility, which allows an improvement of the smoothness at a low surface pressure. The compressible coating is based on nanofibers with a diameter of less than 1000 nm. One of the claims is that the smoothness index of PakerPrint increases 1.2 units when the surface pressure increases between 5 and 10 kgf/cm2. The procedure indicated in the TAPPI T555 Om-99 standard is applied. Nanofibers can be 1). Biopolymers: natural polymer, chitosan, a bicompatible polymer, polycaprolactone, polyethylene oxide, and combinations thereof. two). Inorganic compounds: silica, aluminosilicates, Ti, TiN, Nb Vos, Ta2Os, TiN oxide, among others. 3). Resins: such as polyester, cellulose ether and ester, polyacrylic resin, polysulfide, copolymers, etc. These nanofibers are found in combination with a binder which can be a polymer selected from the group of polyvinyl alcohol, polyvinyl pyrrolidone and their combinations. Nanofibers can be improved by adding oleophobic and hydrophobic additives that can be compounded with fluorocarbon groups.
[0031] Patent application W02008023170A1 entitled "Tailo red control of surface properties by chemical modification" describes a process for the production of a polymer or an inorganic substrate that can adhere to more than one material through surface functionalization bonding to the substrate through a carbon precursor. Nanoparticles (C60 fullerenes or nanotubes) present in an adhesive system comprising a polymer that can be selected from polyolefins, polyesters, epoxy resins, polyacrylates, polyacrylics, polyamides, polytetrafluoroethylene, polyglycosides, polypeptides, polycarbonates, polyethers, polyketones, rubbers , polyurethanes, polysulfones, polyvinyls, cellulose and block copolymers.
[0032] Patent application W0200403S929A1 which is entitled "Method of producing a multilayer coated substrate having improved barrier properties" describes the production of a coated substrate consisting in the formation of a free-flowing multilayer composite, with at least two layers with distinct barrier function and compound-to-substrate contact mechanism. Depending on the anti-barrier function, the number of layers will be required. Laminar nanoparticles (not mentioned), which are immersed in a binder which can be styrene-butadiene latex, styrene-acrylic, latex-acrylonitrile, latex-maleic anhydride, polysaccharides, proteins, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetate, cellulose and its derivatives, among others. The claims for the coated substrate are: 1). Vapor transmission index less than 40 g/(m2/day). two). Cobb value 10 minutes less than 12 g/m2. 3). Oxygen transmission value less than 150 cm3/(m2/24) h/bar) (1 atm, 23°C, 90% relative humidity).
[0033] Patent application W02003078734A1 entitled "With position for surface treatment of paper" describes a surface treatment of paper and cardboard with inorganic nanoparticles and mixtures of organic pigments in the form of a plate, in an aqueous solution that act as a hydrophobic agent, suds suppressor, whitener, improve print quality on paper and are also low cost. Silica nanoparticles and precipitated CaCO3, or mixtures of both. The nanoparticles are dispersed in latex (polymer) selected from the group: butadiene-styrene, acrylate, styrene acrylate, polyvinyl acetate and their mixtures.
[0034] Documents W00076862A1 and ES2304963T3 with the title "Resin/paper multilayer laminated structure, which contains at least one layer of polymer/nanoclay composite and packaging materials made therefrom" describes a laminated structure for packaging and other applications distinct from bottling, which comprises: a paper substrate and at least one layer of polymer/nanoclay composite comprising nanoclay particles with a thickness ranging from 0.7 to 9.0 nanometers applied to said paper substrate (4), where said polymer/nanoclay composite layer is composed of a mixture of a polymer resin with a barrier effect and a nanoclay, where said nanoclay is dispersed in the barrier polymer resin on a nanometric scale and the amount of nanoclay in the composite layer represents between 0.5 and 7.0% by weight of the composite layer.
[0035] Patent CN1449913A entitled "Nano particle water proof corrugated paper board" describes a waterproof corrugated paper. It consists of several layers of lined kraft cardboard and corrugated papers as raw materials which are respectively placed between Kraft facing boards. Said kraft boards and raw materials are subjected to an oil immersion process and a moisture-resistance treatment, and are subsequently protected by a micro-particulate adhesive containing calcium nanocarbonate.
[0036] Patent application CN101623853A entitled "Full resin waterproof sand paper" claims a waterproof resin sandpaper, which comprises six layers of an abrasive layer, an adhesive layer, a base layer for the adhesive, a layer surface treated sandpaper, an original sandpaper cover, and a waterproof top-down treatment cover, wherein the adhesive cover is a mixture of urea formaldehyde resin, red iron and ammonium chloride; the base adhesive cover is a mixture of water-soluble acrylic resin, ammonium resin, fluorine and red iron; the sandpaper treated surface layer is a mixture of nano-sized styrene-butadiene latex oil, a modified starch solution, water and JFS penetrating agent; the waterproof treatment cover is a blend of nano-sized styrene-butadiene latex, a modified starch solution, and JFS penetrating agent.
[0037] The document CN2871192Y entitled "The environmental protective decoration paper material" describes a type of paper material for decoration and environmental protection, which comprises corrugated cardboard on which a waterproof nanocover has been fixed. The above corrugated board is made of B corrugated boards, and can have one or several B boards. The invention not only has the functions of resistance to water or fire, but also protection of the environment and a low price.
[0038] Patent CN2557325Y entitled "Nano particle water resistant corrugated cardboard" describes a water resistant nanoparticle corrugated cardboard by adopting nano-grade calcium carbonate particle technology. The invention includes a plurality of leather and corrugated cardboard plies disposed between the leather plies. The leather covers and corrugated cardboard are joined by a bond of calcium carbonate nanoparticles. The utility of this invention is oriented towards food container and large goods transport.
[0039] In patent application DE102004014483A1 entitled "Coating composition, useful for antimicrobially coating and providing antimicrobial properties to substrates (eg papers, textiles), comprises porous inorganic coating contained in a homogeneous distribution and a cationic polysaccharide" a coating is described. polymeric microbicide whose matrix incorporates inorganic oxides, improving mechanical and microbicide properties. Said coating can be applied to paper or textile substrates and comprises an inorganic porous layer in a homogeneous distribution and a cationic polysaccharide. SiO2 nanosol, which is homogeneously distributed in a cationic polysaccharide.
[0040] In patent application JP2009173909A entitled "Process for production of cellulose nanofiber, and catalyst for oxidation of cellulose" the production of nanocellulose from derivatives of hydroxyl time that confer hydrophobic capacity is mentioned.
[0041] Patent application JP2001163371A entitled "Packaging body having an inorganic compound layer" mentions a method for improving the gas barrier properties for a filling body which consists of coating the body of the filled material with a sol gel or with a nanocomposite to create a film on the surface of the container, which improves the gas-tight properties.
[0042] Patent EP1925732A1 entitled "Packaging material with a barrier coating" describes a packaging material for solid or liquid actives containing paper, cardboard, cardboard, fabrics, wool, wooden articles, natural cellulose, plastic or their compounds , which comprises a moisture resistant and active polymer layer with suspended microparticles and/or microclays. An independent claim is a method of manufacturing (A) a linear polymeric coating, which takes place after preparation of the base material, or in a separation process.
[0043] Patent EP1736504Al entitled "Barrier material and method of making the same" describes the barrier properties of a water-soluble gas-impermeable material which improves if the material is mixed with calcium carbonate nanoparticles having a size from 10 to 250 nanometers. The barrier material meets a substrate to form a substrate with gas tight properties. A cap of heat-sealable material can be applied to the exposed surface of the barrier material. A method for manufacturing the coated substrate is also described. The substrate can be paper, cardboard or cardboard.
[0044] In the article entitled "Development of superhydrophobic coating on a paperboard surface using the Liquid Flame Spray". Surface & Coatings Technology 205 (2010) 436-445, a method for generating nanoscale coatings in a continuous roll-to-roll process at normal pressure is described. The transparent, nanostructured coating, based on titanium dioxide nanoparticles, has been successfully deposited in-line under atmospheric conditions onto pigment-coated cardboard using a thermal projection method called Liquid Flame Spray (LFS). The LFS coating process is described and the influences of process parameters on coating quality are discussed. The nanocoverage was investigated by a scanning field electron emission electron microscope (FEG-SEM), an atomic force microscope (AFM), an X-ray emitted photoelectron spectroscope (XPS) and a contact angle measurement with the water. The highest contact angles with water on the nanocoated cardboard surface were over 160°. Falling water droplets could bounce off the surface, which is illustrated with high-speed footage from the video system. Despite the high hydrophobic capacity, the coating exhibited a tacky nature, creating a high adhesion to water droplets once droplet movement was stopped. Full substrate coverage nano-coating was produced at line speeds of up to 150 m/min. Therefore, LFS coating has to expand the potential to the industrial level as an economical and efficient method for coating large volumes at high in-line speeds.
[0045] article "Adjustable wettability of paperboard by Iiquid flame spray nanoparticle deposition". Applied Surface Science 257(2011)1911-1917 describes the use of the Liquid Flame Spray (LFS) process to deposit TiOx and SiOx nanoparticles onto cardboard to control surface wetting properties. In the LFS process it is possible to create super-hydrophobic or super-hydrophilic surfaces. Changes in moisture are related to the structural properties of the surface, which were characterized using scanning electron microscopy (SEM) and an atomic force microscope (AFM). The surface properties can be attributed as a correlation between the moisture properties of the cardboard and the surface texture created by the nanoparticles. Surfaces can be produced in-line in a one-step roll-to-roll process without the need for additional modifications. On the other hand, functional surfaces with adaptable hydrophilic or hydrophobic capacity can be manufactured simply by proper selection of liquid precursors.
[0046] article "Modifications of paper and paperboard surfaces with a nanostructured polymer coating". Progress in Organic Coatings 69(2010)442-454, describes organic nanoparticles synthesized by imidization of styrene/maleic anhydride copolymers, which are deposited as a first layer on paper and cardboard substrates of a stable aqueous dispersion with a maximum solids content 35% by weight. The morphology, physicochemical characteristics and surface properties of coatings are discussed in this document using scanning electron microscopy, atomic force microscopy, contact angle measurements and Raman spectroscopy. Due to the high glass transition temperature of polymeric nanoparticles, a single micronanoscale structured coating is formed to favor the improvement in gloss, printing properties (print ink spurt test and offset print test ), the hydrophobic capacity of the surface (with a maximum water contact angle of 140°) and the water repellency (reduction of Cobb values). The interaction of the nanoparticles layers with the cellulose paper results in the improvement of the paper's mechanical strength and is attributed to the hydrogen bonds between the nanoparticles and the cellulosic fibers.
[0047] [47] As can be seen, the products that are most used, in general, are nanoparticles (dispersed in polymeric substrates), such as calcium carbonate, silicon oxide, titanium oxide, carbon nanotubes, fullerenes, among others.
[0048] Cellulose nanofibers derived from 4 hydroxy TEMPO, biopolymer nanofibers, inorganic nanofibers or resins, are another type of nanomaterials used in the manufacture of paper and/or cardboard with hydrophobic properties. In some scientific articles it was found the use of certain treatments such as the application of silicon or titanium oxides through the process of "Liquid Flame Spray".
[0049] From the above and experimental tests carried out by the authors of the present invention, the conclusion is that there are still opportunities for innovation in the development of coatings based on nanoparticles that allow better properties of paper and cardboard. For example, it is desirable that the coatings after their application do not affect the printing of paper or cardboard and that they also improve the adhesion on the fins or areas that require the binding of the obtained cardboard boxes. On the other hand, it is desirable that the application of coatings on paper and cardboard does not impede the recycling of the corresponding packages. From previous experiences with other products by the authors of the present patent application, it can also be proven that the use of metal oxides such as silicon oxide without functioning correctly requires greater anchoring, and, in addition, it is possible that they come off over time, which results in a reduction in their performance during packaging handling.
[0050] To improve the performance of hydrophobic coatings on paper and cardboard, it is proposed in the present invention the use of self-assembled silicon oxide nanoparticles with compounds based on silanes and fluorocarbon compounds and, alternatively, the synergistic use of ultrasound to improve the dispersibility of said silicon oxide nanoparticles during their application on the fibers of at least one paper or cardboard surface. BRIEF DESCRIPTION OF THE INVENTION
[0051] In view of the above and with the purpose of presenting a solution to the limitations found, the objective of the invention is to offer a hydrophobic paper or cardboard with self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds directly linked to cellulose fibers from at least one of its surfaces.
[0052] Thus, the objective of the present invention is to offer a method for the production of a hydrophobic paper or cardboard through the steps of preparation of a dispersion of self-assembled silicon oxide nanoparticles with functional groups of si- wool and fluorocarbon compounds in a hydro-alcoholized medium; applying the dispersion to at least one surface of the paper or cardboard; and drying and curing paper or cardboard to directly bond self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds to the cellulose fibers of paper or cardboard. BRIEF DESCRIPTION OF THE DRAWINGS
[0053] Other features of the present invention will be evident from the detailed description below considered in connection with the accompanying drawings.
[0054] It should be understood, however, that the drawings are designed only as an illustration and not as a limiting definition of the invention, in which:
[0055] Figure 1 shows a scheme for forming silane bonds on the surface of silicon oxide nanoparticles formed according to the invention;
[0056] Figure 2 shows a scheme for forming a shell by polymerization of fluorocarbon compounds in nanoparticles according to the invention;
[0057] Figures 3A, 3B and 3C show a physical-chemical fixation scheme of silicon oxide nanoparticles with paper or cardboard fibers by dehydrating the free silane groups according to the invention;
[0058] Figure 4 shows, through a block diagram, the steps of the process of applying hydrophobic coatings on paper and cardboard based on self-assembled silicon oxide nanoparticles according to the present invention;
[0059] Figure 5 shows a photograph of the water contact angle of the paper or cardboard of the present invention;
[0060] Figure 6 shows a microphotograph obtained by scanning electron microscopy of an uncoated state of the art paper or cardboard, in which the cellulose fiber matrix is illustrated;
[0061] Figure 7 shows a microphotograph obtained by scanning electron microscopy of a cellulose fiber of an uncoated state of the art paper;
[0062] Figure 8 shows a microphotograph obtained by scanning electron microscopy of a paper or cardboard with a Michelman® type coating according to the state of the art, in which the matrix of cellulose fibers that is covered is illustrated. by a film-like coating;
[0063] Figure 9 shows a microphotograph obtained by scanning electron microscopy of a cellulose fiber of a paper or cardboard with a Michelman@ type coating according to the state of the art, in which the coating of the type is observed film that extends to other cellulose fibers;
[0064] Figure 10 shows a microphotograph obtained by scanning electron microscopy of a paper or cardboard with a coating according to the invention, in which it is illustrated that there is no film formation on the matrix, but on the fibers of cellulose are coated;
[0065] Figure 11 shows a microphotograph obtained by scanning electron microscopy of a cellulose fiber of a paper or cardboard with a coating according to the invention, in which the coating on the cellulose fiber is observed;
[0066] Figure 12 shows a microphotograph obtained by scanning electron microscopy of the cellulose fibers of paper or cardboard coated with silicon oxide nanoparticles according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0067] Characteristic details of the invention are described in the following paragraphs, which are for the purpose of defining the invention but without limiting its scope.
[0068] The objective of the present invention is to reduce the amount of water that can absorb the paper or cardboard, since its fibers from at least one of its surfaces were coated with self-assembled silicon oxide nanoparticles, as well as to propose a new method for the production of said paper or cardboard that allows reaching Cobb values between 8 and 25 g/m2. The Cobb value indicates the water absorption capacity of papers and cardboards, as well as the amount of liquid that penetrates them; that is, it indicates the weight of water absorbed in a specified time per 1 m2 of paper or cardboard under normal conditions.
[0069] According to the present invention, hydrophobic capacity properties are conferred to paper and cardboard through the use of coatings of self-assembled and functionalized silicon oxide nanoparticles with fluorocarbon groups and silane-type groups, in a dispersion hydroalcoholic colloidal agitated by ultrasound.
The fluorocarbon groups used are, for example: 2,3,5,6-tetrafluoro-4-methoxystyrene, fluorinated acrolamide monomers or 1H,1H,2H,2H-5-perfluoro octyl triethoxy silanes.
[0071] The silane-type groups used are: 3-mercapto propyl trimethoxy silane (MPTMS), glycidoxy propyl trimethoxy silane (GLYMO), bis[3-(triethoxysilyl)propyl]tetrasulfide (TETRA-S), bis-triethoxy silyl ethane (BTSE), dichloro diphenyl silane, 3-isocyanate propyl trimethoxy silane, 1,2-bis(chlorodimethylsilyl)ethane, N-[3-(trimethoxysilyl)propyl]aniline, amino propyl triethoxy silane (APTES), 3-( mercaptomethyl)octyl)silane triol, 2-(2-mercaptoethyl)pentyl)silane triol, or bis(triethoxysilyl)propyl]amine (BAS).
[0072] The hydrophobic characteristics of silicon oxide nano-particle coatings on paper are maximized when the paper is immersed in the hydroalcoholic suspension continuously stirred by some mechanical means, whether with the aid of ultrasound or not, and the resulting coating is dried and cured at temperatures from about 80°C to about 170°C. Once heat is applied to evaporate the solvents containing the dispersion and at the same time promote the anchoring or direct binding of the particles onto the paper fibers, it is possible to obtain Cobb values from about 8 g/m2 to about 25 g/ m2.
[0073] The present invention stands out from the previous ones, due to the fact that the coating application procedure does not affect the printing of paper or cardboard, further improving the adhesion on the fins or areas that require the agglutination of the obtained cardboard boxes. On the other hand, the process of applying the coating according to the present invention to paper and cardboard does not prevent packaging recycling and facilitates its adaptation to industrial machines for the production of boxes. Paper and board products obtained in this way have high levels of moisture resistance and high contact angle between water and coating.
[0074] A fundamental concept when considering the use of hybrid materials or composite materials to obtain a certain functionality in a material such as the hydrophobic capacity of cellulose and its derivatives is the existing compatibility between organic or polymeric materials and materials inorganics. This compatibility is usually characterized by having a certain degree of antagonism, since many of the inorganic materials have a hydrophilic character, while polymers have a hydrophobic character. However, this property which may be antagonistic in separate materials may have a synergistic effect in one direction or the other as required in hybrid or composite materials.
[0075] This situation makes an important part of the process of preparing composite materials to focus on a way to improve this compatibility by modifying the hydrophilic character of the inorganic materials to obtain the best union of the inorganic material-organic matrix in the interfacial zones of both materials, one that, if we want to take advantage of the barrier effect of inorganic materials, these must be strongly bonded to the matrix.
[0076] The adhesion between inorganic materials and the polymeric matrix can be attributed to a series of mechanisms that can occur at the interface, as isolated phenomena or by interaction between them. Physical and chemical methods of modifying the interface promote different levels of adhesion between the inorganic material and the polymer matrix. Physical treatments can change the structural and surface properties of inorganic aggregates influencing the mechanical bonds with the polymer matrix. However, many strongly polarized aggregates are incompatible with hydrophobic polymers. When two materials are incompatible, action can be taken by introducing a third material called a coupling agent, which has properties intermediate between the other two, and thus creating a degree of compatibility.
[0077] Chemical compounds containing methanol groups (- CH2OH) form stable covalent bonds with cellulose charges. Hydrogen bridge-type bonds between the aggregate and the matrix can also be formed in this reaction.
[0078] The surface energy of inorganic aggregates is closely related to the hydrophilic capacity and the hydrophobic capacity of composite materials. Silanes as coupling agents that can contribute to the hydrophilic or hydrophobic properties of the interface. Organosilanes are the main group of coupling agents for polymers with glass or silicon oxide aggregates. Silanes were developed to couple different polymers to mineral aggregates in the manufacture of composite materials.
[0079] The silane-based coupling agents can be represented by the following formula: R-(CH2)n-Se(OR')3, where n functional = 0 - 3, OR' is the hydrolyzable alkoxy group, and R is the organic group.
[0080] The organic functional group (R) in the coupling agent is the one that produces the reaction with the polymer. It acts as a copolymerization agent and/or to form an interpenetration network. Alkalosilanes undergo hydrolysis in the bond-forming step in both acidic and basic environments. These reactions of silanes with the hydroxyls on the surface of the aggregates can give rise to the formation of polysiloxane structures.
[0081] In the present invention, the use of self-assembly techniques for the functionalization of silicon oxide nanoparticles before their dispersion in a polymer matrix is exposed.
[0082] Self-assembly can be defined as the spontaneous formation of complex structures from previously designed units of smaller size. Self-assembled monolayers are ordered molecular units that are formed by spontaneous adsorption (chemosorption) of a surfactant on a substrate containing the first a functional group with affinity to that substrate.
[0083] The sequence of self-assembly reactions that is carried out, according to the present invention, for the purpose of preparing a hybrid material to give a paper or board a hydrophobic character or resistance to water absorption is described in follow.
[0084] For the preparation of SiO2 nanoparticles with the intention of generating dispersions in a hydroalcoholic dissolution, TEOS was used as a starting product, which dissolves in an ethanol-water mixture and stabilizes at a pH of about 3.5 to about 3.75 is reacted at temperatures of about 25°C to about 40°C for a time of about 15 minutes to about 90 minutes, forming a clear or white colloidal dissolution. .

[0085] Then, the TEOS tends to hydrolyze, generating nuclei of the formula (SiO2)x.

[0086] Other silanes were used such as: 3-mercapto propyl trimethoxy silane (MPTMS), glycidoxy propyl trimethoxy silane (GLYMO), bis[3-(triethoxysilyl)propyl]tetrasulfide (TETRA-S), bis-triethoxy silyl ethane ( STSE), dichloro diphenyl silane, 3-isocyanate propyl trimethoxy silane, 1,2-bis(chlorodimethylsilyl)ethane, n-[3-(trimethoxysilyl)propyl]aniline, amino propyl triethoxy silane (APTES), 3-(mercaptomethyl)octyl )silane triol, 2-(2-mercaptoethyl)pentyl)silane triol, bis-(triethoxysilyl)propyl]amine (BAS), and their combinations, in order to replace the hydroxyl groups and generate on the surface of nanoparticles of silicon oxide functional groups that can give rise to self-assembly reactions on the surfaces of the generated silicon oxide nanoparticles nuclei. In Figure 1 it is shown how these silanes can form bonds on the surface of the formed silicon oxide nanoparticles.
[0087] The third stage of the synthesis process of functionalized silicon oxide nanoparticles consists of creating the shell of the nanoparticles. The shell of these nanoparticles is made up of chains of fluorocarbon molecules. These shells are prepared by means of a polymerization or condensation reaction on the surface of the nanoparticle cores. Depending on the type of functional group, different molecules are used to form the fluorocarbon shell.
[0088] In some of these polymerizations it is necessary the intervention of small amounts of catalysts, and these catalysts are of the acid type, such as carboxyl groups, compounds of Q(I), basic medium such as ammonia or potassium carbonate. A reaction scheme is shown in Figure 2.
[0089] It is necessary to use a bis-silane such as BS, TE-TRA-S or BTSE and the fluorocarbon compound with silane groups. These reactions are carried out at pH 3.5 AND they are left to react for 30 minutes at 25°C. From these three-step reactions, particles of sizes between 10 nm and 130 nm are prepared. Fluorocarbon groups such as 2,3,5,6-tetrafluoro-4-methoxy styrene, fluorinated acrolamide monomers or 1H,1H,2H,2H-perfluoro octyl triethoxy silanes are used. Silane-type groups such as: 3-mercapto propyl trimethoxy silane (MPTMS), glycidoxy propyl trimethoxy silane (GLYMO), bis[3-(triethoxysilyl)propyl]tetrasulfide (TETRA-S), bis-triethoxy silyl ethane (BTSE) , dichloro diphenyl silane, 3-isocyanate propol trimethoxy silane, 1,2-bis(chlorodimethylsilyl)ethane, n-[3-(trimethoxysilyl)propyl]aniline, amino propyl triethoxy silane (APTES), 3-(mercaptomethyl)octyl)silane triol, 2-(2-mercaptoethyl)pentyl)silane triol, bis-(triethoxysilyl)propyl]amine (BAS), and combinations thereof.
[0090] In order to avoid agglomeration and precipitation of colloidal nanoparticles, in the present invention it is alternatively proposed the use of ultrasound and the synergistic effect of the cavitation generated by the ultrasound and the self-assembly that prevents the nanoparticles from a once dispersed, they re-agglomerate. Due to the repulsions that are exerted between particles, in a suitable dispersion medium and due to their superficial functionalization, it is possible to obtain a good dispersion even at concentrations above 25%.
[0091] In general, the ultrasonic dispersion is carried out by means of an ultrasound generator through one or more piezoelectric transducers that transform the electrical signal into a mechanical vibration. This vibrational energy is transmitted to the liquid at a frequency of up to 200,000 oscillations per second. These pressure and vacuum oscillations create a large amount of micro-bubbles, which implode at high speed, contributing to the breakdown of nanoparticle agglomerates.
[0092] The use of a combined form of ultrasound and/or pulsed ultrasound at frequencies between about 10 KHz and about 150 KHz at temperatures from about 10°C to about 250°C in aqueous or organic solvents produces the breakdown of nanoparticle agglomerates. On the other hand, the addition of molecules, capable of functionalizing the surface of the nanoparticles by self-assembly, in the ultrasound bath allows obtaining nanopowders with a high degree of particle disaggregation, mainly due to their functional groups that prevent them from these are aggregated due to electrostatic interactions existing between the nanoparticles. On the other hand, self-assembled and functionalized nanoparticles allow for greater dispersion and prevent the appearance of agglomerates of nanoparticles or aggregates.
[0093] The dispersion of the self-assembled nanoparticles is carried out in a hydroalcoholized medium, wherein the dispersion has a density of about 0.96 g/cm3 to about 0.99 g/cm3 and a pH of about 3 to about 4.5.
[0094] The alcohol used to prepare the dispersion can be ethanol, propanol, methanol and their combinations.
[0095] The deposition of colloidal dissolutions of silicon oxide nanoparticles on at least one surface of the paper or cardboard results in deposited nanoparticles without them being fixed by any type of chemical or physicochemical interaction on it, except for a physical occlusion in the empty spaces that have paper or cardboard. For the physical-chemical fixation of silicon oxide nanoparticles with the fibers of paper or cardboard at least one of its external surfaces, it is necessary to dehydrate free silanol groups, giving rise to a three-dimensional network as shown in Figure 3A.
[0096] Subsequently, during the paper immersion-extraction process, the silanols migrate and settle on the paper or cardboard as shown in Figures 3B and 3C. According to experimental tests carried out by the authors of the present invention and despite the functionalization of the silicon oxide nanoparticles, in the container that contains the suspension of the silicon oxide nanoparticles it is necessary to maintain their good dispersion and prevent them from agglomerating. In general, it is acceptable that mixtures of organic polymers with inorganic or metallic particles give rise to a phase separation with agglomeration of the nanoparticles which later results in poor properties. But, in addition, when the particles have diameters of less than 50 nanometers, it is really very difficult to obtain a homogeneous mixture if the amount of aggregate exceeds 5% by weight or if the polymers that are used have a high viscosity in the molten state. For this reason, new methods such as ultrasound are needed to fulfill these requirements in terms of dispersion.
[0097] Finally, through a heat treatment, polymerization of the coating is obtained.
[0098] This heat treatment is key to obtain a super-hydrophobic coating on the surface of paper or cardboard.
[0099] Briefly but not limiting, the method for the production of hydrophobic paper or cardboard of the present invention is diagramed by means of the block diagram of Figure 4 in which the steps of the method are indicated with different numbers and which are described below:
[00100] In step 100, alternatively, if the self-assembled nanoparticles are not available, a synthesis is performed by self-assembly of silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds in a hydro-alcoholized medium agitated by ultrasound.
[00101] Since the nanoparticles are already self-assembled, in step 200 a dispersion is prepared by stirring by mechanical means of self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds in a hydroalcoholized medium. Dispersion of the nanoparticles can be aided by the application of ultrasound with a continuous or pulsed frequency from about 10 KHz to about 150 KHz.
[00102] Once the dispersion is prepared, in step 300 the dispersion is applied on at least one surface of the paper or cardboard in which the property of hydrophobic capacity is required. This application can be through immersion-extraction of paper or cardboard in the dispersion of nanoparticles, with the purpose of reacting and binding the Si-OH groups of the nanoparticles with the -OH groups of the cellulose fibers of paper or cardboard. This application, in turn, can be dosed and evenly distributed over the surface of the paper or cardboard using a spatula.
[00103] Finally, in step 400, the paper or cardboard is dried and cured to directly bind the self-assembled silicon oxide nanoparticles with functional groups of silanes and fluorocarbon compounds to the cellulose fibers of the paper or cardboard.
[00104] It is important to indicate that, although an expert in the art can verify that, independently, each of the steps belongs to the state of the art, the synergistic effect of the set of five steps comprising the method of application of nanoparticles functionalized and dispersed according to the present invention produces effects not reported in the state of the art and that, if any of the steps indicated is not carried out, it is not possible to obtain neither the hydrophobic capacity properties nor the improvements of the coatings reported in the present invention.
[00105] As observed experimentally, a very important factor that directly affects the curing reactions of cardboard is the time and temperature of the heat treatment, which has a very close relationship with the level of crosslinking of the active components of the coating and consequently with the Cobb values.
[00106] According to the above, it is observed that, with a longer curing time and a higher temperature, it is possible to obtain coatings with lower Cobb values.
[00107] As discussed previously, the drying and curing process is key to obtaining a super-hydrophobic coating on the surface of paper or cardboard; that is, it is the heat that directly cooperates in the fixation of the nanomaterials on the surface of the paper or cardboard, generating not only this connection with the fibers, but also promoting the interactions between the nanoparticles in order to produce a nanostructured coating that allows a greater effect. lotus, making the paper more resistant to moisture.
[00108] Due to the fact that the intercrossing process between paper or cardboard fibers and applied nanoparticles is based on the dehydration of the Si-OH functional groups of fluorocarbon and -OH of cellulose, the improvement in Cobb values directly depends on the process of their dehydration and of the phenomenon of intercrossing of Si-OH groups and their interaction with the cellulose fibers. This interaction generates a greater amount of these groups that react and increase the union of silicon oxide nanoparticles to the surface of each fiber, and with this, by increasing the temperature and curing time, optimization of the surface cured material is obtained. cellulosic. During these thermal processes that take place at a temperature of about 80°C to about 170°C, the paper or cardboard fiber loses a certain amount of chemically bound water, which after the curing process must be recovered to avoid a destabilization in fiber accommodation and stiffness.
[00109] Thus, it was determined that the curing conditions for the preparation of a paper or cardboard of the present invention with Cobb values close to 20 g/m2 correspond to a temperature of 150°C and a time of 180 seconds when making use of a immersion time in the suspension of 10 seconds and coating amounts close to 3.5 g/m2.
[00110] In the same way as for the curing temperature, an excess of heat treatment time causes a reduction of the values of resistance to humidity, which can be proven in tests carried out at 170°C for 240 seconds.
[00111] The contact angle of surface water with self-assembled nanoparticles on the paper or cardboard of the present invention is from about 100° to about 140°, as illustrated in Figure 5. EXAMPLES OF CARRYING OUT THE INVENTION
[00112] The invention will now be described with respect to the following examples, which are presented solely for the purpose of representing the way to carry out the implementation of the principles of the invention. The following examples should not be an exhaustive representation of the invention, nor should they limit its scope.
[00113] To prepare the hydrophobic coatings of the self-assembled and functionalized silicon oxide nanoparticles, according to the present invention, a hydroalcoholic colloidal dispersion of nanoparticles with fluorocarbons with a density of 0.98 g/cm3 and a pH of 3.6. This suspension was agitated with ultrasound for 30 minutes. Once the stirring process was finished, the suspension was poured into a tray and paper coating was started.
[00114] Two types of cardboard were prepared, one with a compressive strength of 220.63 kPa (32 lb/in2) and the other with a strength of 303.37 kPa (44 lb/in2). Both according to the standard ECT method. The composition of the cardboards for each case was as follows: 32 ECT Resistance (Liner L33A, Midium Mll0U, Liner LT170) and 44 ECT Resistance (Liner L42A, Midium M150U, Liner LT170t). TEST 1. 44 ECT PAPER
[00115] Table 1 shows the temperature conditions of the different critical parameters in the process
Table 1
[00116] The production speed was 80 m/min. In this test, it was observed that, when the dispersion is stopped, the product in the tray is not homogeneous, and therefore the agitation was started again, and in this way it was possible to observe that the effect decreased until it became homogeneous again. TEST 2. 44 ECT PAPER
[00117] Table 2 shows the temperature conditions of the different critical parameters in the process.
Table 2
[00118] The production speed was 60 m/min, TEST 3. 32 ECT PAPER
[00119] In Table 3 the temperature conditions of the different critical parameters in the process are indicated.
Table 3
[00120] The production speed was 80 m/min,
[00121] With the coated sheets of paper sheets, boxes were manufactured, and these were manipulated in such a way that the coating on the inner face and the outer face was obtained.
[00122] In Table 4 can be seen a comparison of the Cobb values obtained, the contact angles, the speed of passage of water and the amount of material used for each test.
Table 4
[00123] The amount of material per square meter is less than 1 g/m2 in tests in general, the best Cobb values are 15 in cardboard where it was possible to obtain contact angles greater than 128° and little liquid penetration . Much higher contact angles than those obtained with commercial Michelman® type coatings.
[00124] It is important to indicate that commercially available coatings such as Michelman®, the amount of material required to achieve Cobb values between 25 and 30 lies between 4 g/m2 and 16 g/m2.
[00125] In Figures 6 to 11, a microphotograph obtained by scanning electron microscopy is illustrated for both a paper or cardboard of the prior art without coating (see Figure 6) and the respective cellulose fiber detail (see Figure 7) , a paper or cardboard with a Michelman® type coating according to the state of the art (see Figure 8) and respective cellulose fiber detail (see Figure 9), as well as a paper or cardboard with a coating according to with the invention (see Figure 10) and respective cellulose fiber detail (see Figure 11), in such a way that it is possible to see the comparative effect between a film-like coating (see Figures 8 and 9) with the effect coating on fibers of the present invention (see Figures 10 and 11).
[00126] Table 4 also shows the results obtained as a function of the Cobb values, the contact angle and the water flow velocity. In this table it is possible to observe very low Cobb values in all tests (from 16.7 g water/m2 to 26.8 g water/m2) corresponding to water flow rates of 0.036 g/s to 0.005 g/s, the which shows an important reduction in the passage of water in both paper and cardboard due to the coating. From additional experimental tests, it can be proven that, with the procedure of the present invention, it is possible to control Cobb values in a range of 8 gwater/m2 to 25 gwater/m2. It is also possible to observe high contact angles for all cases (from 118.1° to 128.9°), which confirms the good hydrophobic capacity of the coatings applied to both paper and cardboard. On very hydrophobic surfaces, the contact angle is greater than 100 or in these cases the water rests on the surface but does not wet them, nor extends over them, giving rise to the so-called Lotus effect. In the present invention, the lotus effect is promoted by the self-assembled silicon oxide nanoparticles that coat the cellulose fibers, giving rise to a nanorugged topography on their surface as shown in Figure 12.
[00127] To assess the degree of hydrophobic capacity, the measurement of the contact angle was used, and to measure the moisture absorption capacity of paper and cardboard, IMPEE-PL020 and TAPPI standards were used, which allow to quantify the values of Cobb and the speed of water penetration.
[00128] By carrying out the tests at an industrial level, it could be seen that the nanostructured hydrophobic coating prepared and applied according to the present invention does not affect the printing of paper or cardboard and improves agglutination in the fins or areas that require agglutination of the obtained cardboard boxes. This is because the silicon oxide nanoparticles are directly bonded onto the cellulose fibers as shown in figure 5, unlike other commercial products in which a monolithic layer is formed that covers the surface of the paper or cardboard, modifying the printing and agglutination of the cardboard when producing the boxes. Furthermore, from industrial level tests, it could be confirmed that nanostructured coatings of well-dispersed silicon oxide nanoparticles reduce the amount of hydrophobic material that is required per unit surface of paper or cardboard, facilitating the recycling process of the said packages.
[00129] Although the invention has been described with respect to a preferred embodiment, those skilled in the art will understand that they can make various changes and can substitute equivalents for their elements without deviating from the scope of the invention. Furthermore, they can make many modifications to adapt a particular situation or material to the content of the invention, without deviating from the fundamental scope of the invention. Therefore, it is intended that the invention is not limited to the particular embodiment described as the best mode contemplated for carrying out the present invention, but the invention is to include all embodiments that are within the scope of the appended claims.

权利要求:
Claims (11)
[0001]
1. Hydrophobic paper or cardboard including cellulose fibers and self-assembled silicon oxide nanoparticles, characterized in that the self-assembled silicon oxide nanoparticles are functionalized with a functional silane group and a fluorocarbon compound; wherein the silane functional group is selected from the group consisting of 3-mercapto propyl trimethoxy silane (MPTMS), glycidoxy propyl trimethoxy silane (GLYMO), bis[3-(triethoxysilyl)propyl]te-trasulfide (TETRA-S) , 1,2-bis[triethoxysilyl]ethane (BTSE), dichloro diphenyl silane, 3-isocyanate propyl trimethoxy silane, 1,2-bis(chlorodimethylsilyl)ethane, N-[3-(trimethoxysilyl)propyl]aniline, 3-( mercaptomethyl)octyl)silane triol, 2-(2-mercaptoethyl)pentyl)silane triol, and combinations thereof; wherein the fluorocarbon compound is selected from the group consisting of 2,3,5,6-tetrafluoro-4-methoxy styrene, fluorinated acrolamide monomers, 1H,1H,2H,2Hperfluoro octyl triethoxy silane, and combinations thereof ; and the self-assembled silicon oxide nanoparticles being directly bonded to cellulose fibers from at least one of their hydrophobic paper or board surfaces through the silane functional group.
[0002]
2. Paper or cardboard, according to claim 1, characterized by the fact that it has a Cobbs value of 8 g/m2 to 25 g/m2 and a contact angle with water of 100° or 140° .
[0003]
3. Paper or cardboard, according to claim 1, characterized by the fact that the amount of self-assembled silicon oxide nanoparticles is less than 3.5 grams per square meter of paper or cardboard.
[0004]
4. Method for producing a hydrophobic paper or cardboard, characterized in that it comprises the steps of: preparing a dispersion of self-assembled and functionalized silicon oxide nanoparticles with a functional silane group and a fluorocarbon compound in a hydroalcoholized medium at a pH of 3 to 4.5; wherein the silane functional group is selected from the group consisting of 3-mercapto propyl trimethoxy silane (MPTMS), glycidoxy propyl trimethoxy silane (GLYMO), bis[3-(triethoxysilyl)propyl]te-trasulfide (TETRA-S) , 1,2-bis[triethoxysilyl]ethane (BTSE), dichloro diphenyl silane, 3-isocyanate propyl trimethoxy silane, 1,2-bis(chlorodimethylsilyl)ethane, N-[3-(trimethoxysilyl)propyl]aniline, 3-( mercaptomethyl)octyl)silane triol, 2-(2-mercaptoethyl)pentyl)silane triol, and combinations thereof; and wherein the fluorocarbon compound is selected from the group consisting of 2,3,5,6-tetrafluoro-4-methoxy styrene, fluorinated acrolamide monomers, 1H,1H,2H,2Hperfluoro octyl triethoxy silane, and their combinations; applying said dispersion on at least one surface of the paper or cardboard comprising cellulose fibers; and drying and curing said paper or cardboard to directly bond said self-assembled silicon oxide nanoparticles to the cellulose fibers of the paper or cardboard by covalent bonds through the silane functional group.
[0005]
5. Method according to claim 4, characterized in that in the step of preparing a self-assembled dispersion of silicon oxide nanoparticles, the dispersion has a density of 0.96 g/cm3 to 0.99 g /cm3.
[0006]
6. Method according to claim 4, characterized in that in the step of preparing a self-assembled dispersion of silicon oxide nanoparticles, the hydroalcoholized medium includes an alcohol selected from a group consisting of ethanol, propanol, methanol and its combinations.
[0007]
7. Method according to claim 4, characterized in that in the stage of dispersion of self-assembled silicon oxide nanoparticles, the nanoparticles are dispersed by mechanical agitation with the aid of ultrasound at a continuous or pulsed frequency from 10 KHz to 150 KHz.
[0008]
8. Method according to claim 4, characterized in that in the step of applying said dispersion on at least one surface of the paper or cardboard consists of immersion-extraction of the paper or cardboard in said dispersion and includes the step of dosing and distributing said dispersion onto the surface of the paper or cardboard by means of a spatula.
[0009]
9. Method according to claim 4, characterized in that in the step of applying said dispersion on at least one surface of the paper or cardboard, the dispersion is applied in an amount of less than 3.5 grams per square meter of paper.
[0010]
10. Method according to claim 4, characterized in that the step of drying and curing said paper or cardboard is carried out at a temperature of 80°C to 170°C.
[0011]
11. Method according to claim 4, characterized in that the step of preparing a dispersion of self-assembled silicon oxide nanoparticles is carried out at a temperature of 10°C to 250°C.

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法律状态:
2017-07-04| B08F| Application dismissed because of non-payment of annual fees [chapter 8.6 patent gazette]|

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2017-10-03| B08G| Application fees: restoration [chapter 8.7 patent gazette]|

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2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2019-10-01| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-04-13| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-06-29| 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 12/04/2013, 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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MXMX/A/2012/004387|2012-04-13|

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MX2012004387A|MX366743B|2012-04-13|2012-04-13|Hydrophobic paper or cardboard with self-assembled nanoparticles and method for the production thereof.|

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PCT/MX2013/000047|WO2013154414A1|2012-04-13|2013-04-12|Hydrophobic paper or cardboard with self-assembled nanoparticles and method for the production thereof|

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