CN101548047B - Cellulosic product - Google Patents

Abstract

The present invention relates to a cellulose product comprising thermoplastic microspheres and charged aromatic acrylamide-based polymers. The present invention also relates to a method of producing a cellulosic product comprising: providing an aqueous suspension containing cellulosic fibers; adding thermoplastic microspheres and a charged aromatic acrylamide-based polymer to said suspension; and adding the resulting The suspension is dehydrated. The invention also relates to the use of said cellulose product as liquid packaging board.

Description

Cellulose Products

technical field

The present invention relates to a cellulose product containing thermoplastic microspheres and its production and use.

Background technique

“World Pulp & Paper Technology(世界纸浆与造纸技术)”1995/96，“The International Review for the Pulp &Paper Industry(纸浆与造纸工业国际综述)”第143-145页。Cellulose products containing thermoplastic microspheres are known in the prior art, see US Patent Nos. 3,556,934; 4,133,688 and 5,125,996; US Patent Application Publication No. 2003/0152724; Japanese Patent Laid-Open Nos. 2002-254532 and 2003-105693; Japanese Patent No. 2689787; International Patent Application Publication Nos. WO 2001/54988, 2004/099499; 2004/113613 and 2006/068573; and

"World Pulp & Paper Technology" 1995/96, "The International Review for the Pulp & Paper Industry" pp. 143-145.

Thermoplastic microspheres can be incorporated into cellulose products to provide low density high pulp paper and paperboard products such as insulated containers such as paper cups that can be used to serve hot and cold beverages. However, according to experience, the porosity of such cellulose products may be too high, thereby reducing the resistance of sized cellulose products containing thermoplastic microspheres to the penetration of gas and aqueous liquids, especially the resistance to edge wicking of aqueous liquids .

It would be advantageous to be able to provide cellulose products containing thermoplastic microspheres which exhibit improved properties, especially improved porosity and edge wicking resistance.

Summary of the invention

The present invention relates to a cellulose product comprising thermoplastic microspheres and charged aromatic acrylamide-based polymers.

The invention also relates to a method of producing a cellulose product comprising:

(i) providing an aqueous suspension comprising cellulosic fibers;

(ii) adding thermoplastic microspheres and a charged aromatic acrylamide-based polymer to said suspension; and

(iii) Dehydrating the resulting suspension.

The invention also relates to the use of a cellulose product comprising thermoplastic microspheres and a charged aromatic acrylamide-based polymer as liquid packaging board.

Detailed description of the invention

Incorporation of thermoplastic microspheres in cellulosic products generally increases porosity, increases volume and decreases density compared to cellulose products without thermoplastic microspheres. According to the present invention, it has been found that the increase in porosity with a corresponding increase in volume can be lower and that improved lower porosity is achieved by cellulose products containing thermoplastic microspheres and charged aramid-based polymers. Herein, improved porosity means improved resistance to penetration of gases and/or aqueous liquids and improved resistance to edge wicking penetration of aqueous liquids of sized cellulose products containing thermoplastic microspheres. Thus, the present invention can provide cellulose products with improved properties.

The term "cellulosic product" as used herein refers to all types of cellulosic products including pulp bales and cellulosic products in the form of sheets and webs, preferably paper and board. Cellulosic products may comprise one or several layers containing cellulose fibers, including single-ply and multi-ply paper and board products.

According to the present invention, a cellulosic product is provided by a process comprising the steps of adding thermoplastic microspheres and a charged aromatic acrylamide-based polymer to an aqueous suspension of cellulosic, followed by dehydration of the resulting suspension to form a cellulosic product . In a preferred embodiment, the present invention provides a single ply cellulosic product such as paper and paperboard comprising thermoplastic microspheres and charged aramid-based polymers, wherein the thermoplastic microspheres and charged aramid The amide-based polymer is preferably distributed throughout the cellulosic product, more preferably substantially uniformly throughout the cellulosic product.

In another preferred embodiment, the present invention provides a multilayer cellulosic product such as paper and paperboard comprising two or more layers containing cellulosic fibers, wherein at least one of the two or more layers One layer contains thermoplastic microspheres and charged aramid-based polymers. The thermoplastic microspheres and the charged aramid-based polymer are preferably distributed throughout at least one of the two or more layers, more preferably substantially uniformly distributed throughout the two or more layers of at least one layer. The multilayer cellulosic product of the present invention can be formed by forming at least one layer comprising cellulosic fibers, thermoplastic microspheres and charged aramid-based polymers and attaching the at least one layer to one or more layers comprising cellulosic fibers. layer to form a multilayer cellulose product. For example, multilayer cellulosic products can be produced by forming the layers separately in one or several web-forming units, which are then laminated in the wet state. Examples of suitable grades of multilayer cellulosic products of the present invention include three to seven layers comprising cellulosic fibers and at least one of said cellulosic layers comprising thermoplastic microspheres and a charged aramid-based polymer. Those ones. In multilayer cellulosic products having three or more layers, preferably at least one middle layer comprises thermoplastic microspheres and a charged aramid-based polymer.

Cellulosic products of the present invention in the form of sheets and webs, including single-ply and multi-ply products such as paper and board, preferably have a grammage of from about 50 to about 500 g/ ^m2 , most preferably from about 100 to about 300 g/ ^m2 .

The term "paperboard" as used herein refers to various types of paperboard containing cellulose fibers, including cardboard such as solid bleached sulphate board (SBS) and solid unbleached sulphate board (SUS); boxboard such as folding board (FBB), folding Cartonboard, liquid packaging board (LPB), including gable top, aseptic, brick, non-sterile packaging and retortable; bleached liner chipboard (WLC), unbleached kraft board, gray Paperboard and recycled board; linerboard and containerboard, including white kraft board, fully bleached kraft board, strong linerboard, white kraft tough liner, unbleached kraft board, Tough containerboard and recycled linerboard; corrugated board. In a preferred embodiment of the invention the cellulosic product is liquid packaging board.

According to the invention, cellulosic products and suspensions may contain cellulosic fibers of different types and it preferably contains at least 25% by weight, more preferably at least 50% by weight, of such fibers based on dry matter. The cellulosic products and suspensions may be made from and contain various types of pulps such as bleached or unbleached pulps based on virgin fibers and/or recycled fibres. Pulp can be based on chemical pulps such as kraft, sulfite and organosolvent pulps, mechanical pulps such as thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refined and groundwood pulps, from hard Fibers of wood and softwood are also based on recycled fibers, optionally from deinked pulp (DIP), and mixtures thereof. Cellulosic products can also be made from fibers produced from annual plants such as elephant grass, bagasse, flax, straw, and the like. Cellulosic products may comprise one or several layers from the same or different kinds of pulp. Examples of multilayer compositions include bleached chemical pulp top/DIP, CTMP or mechanical pulp middle/bleached chemical pulp back; bleached chemical pulp top/DIP, CTMP or mechanical mid/mechanical back; bleached chemical pulp top /DIP, CTMP or mechanical pulp middle layer/unbleached chemical pulp back layer; and bleached chemical pulp top layer/unbleached chemical pulp back layer, where the front and back sides are optionally coated. Front side means the side intended to face the outside of the finished product or package.

According to the invention, the cellulose product contains thermoplastic microspheres which may be expanded or unexpanded heat-expandable microspheres. The thermoplastic microspheres are preferably expanded and added to the cellulosic suspension or pulp during the production process of the cellulose product as pre-expanded microspheres or unexpanded heat-expandable microspheres, preferably making the unexpanded heat-expandable microspheres The microspheres are expanded by heating in the cellulosic product production process, for example during the heat drying stage, or in a separate process step, for example in a drum heater or a laminator. The microspheres can be caused to swell while the cellulosic product is still wet or when the cellulosic product is completely or almost completely dry. The microspheres are preferably added in the form of a slurry which may optionally contain other additives which are desired to be incorporated in the cellulosic suspension.

The thermoplastic microspheres of the present invention preferably comprise a thermoplastic polymer shell enclosing a propellant. The propellant is preferably a liquid whose boiling temperature is not higher than the softening temperature of the thermoplastic polymer shell. When heating the heat-expandable thermoplastic microspheres, the propellant increases the internal pressure while the shell softens, which causes the microspheres to expand significantly. Expandable and pre-expanded thermoplastic microspheres can be trademarked (Akzo Nobel) is commercially available and sold in various forms such as as dry free-flowing granules, water slurry or partially dewatered wet cake. They are also well described in the literature such as U.S. Patent Nos. 3,615,972; 3,945,956; 4,287,308; 5,536,756; 6,235,800; 072160; and Japanese Patent Laid-Open Nos. 1987-286534; 2005-213379 and 2005-272633; which are incorporated herein by reference.

The thermoplastic polymer shell of the thermoplastic microspheres is preferably made of homopolymers or copolymers obtained by polymerizing ethylenically unsaturated monomers. Those monomers may be, for example, nitrile-containing monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile or crotononitrile; acrylates such as methyl acrylate or ethyl acrylate; esters; methacrylates such as methyl methacrylate, isobornyl methacrylate or ethyl methacrylate; vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate, vinyl ethers such as alkylethylene Base ethers such as methyl vinyl ether or ethyl vinyl ether, other vinyl monomers such as vinylpyridine; vinylidene halides such as vinylidene chloride; styrenes such as styrene, vinyl halides or alpha-formaldehyde styrene; or dienes such as butadiene, isoprene, and chloroprene. Mixtures of any of the above monomers may also be used.

Propellants for thermoplastic microspheres can include hydrocarbons such as propane, butane, isobutane, n-pentane, isopentane, neopentane, hexane, isohexane, neohexane, heptane, isoheptane, octane or isooctane or mixtures thereof. Besides them, other hydrocarbons such as petroleum ether or chlorinated or fluorinated hydrocarbons such as methyl chloride, dichloromethane, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, trichloro Fluoromethanes, perfluorocarbons, etc.

Expandable thermoplastic microspheres suitable for the present invention preferably have a volume median particle size of from about 1 to about 500 μm, more preferably from about 5 to about 100 μm, most preferably from about 10 to about 50 μm. The temperature at which expansion begins (referred to as _Tonset ) is preferably from about 60 to about 150°C, most preferably from about 70 to about 100°C. The temperature at which maximum expansion is achieved (referred to as _Tmax ) is preferably from about 90°C to about 180°C, most preferably from about 115°C to about 150°C.

Pre-expanded thermoplastic microspheres suitable for the present invention preferably have a volume median particle size of from about 10 to about 120 μm, most preferably from about 20 to about 80 μm. The density is preferably from about 5 to about 150 g/dm ³ , most preferably from about 10 to about 100 g/dm ³ . Although pre-expanded thermoplastic microspheres are directly commercially available, they can also be provided, for example, by in-situ thermal expansion of unexpanded expandable thermoplastic microspheres immediately after addition to the cellulose suspension, if the T of the expandable microspheres _starts below This becomes more convenient at about 100°C so that steam can be used as the heating medium.

In the production process of cellulosic products, the charged aromatic acrylamide-based polymers of the present invention are preferably used as retention aids, optionally in combination with other additives of cellulosic suspensions such as siliceous materials, flocculants and other organic polymers, Drainage aids and/or dry strength agents. As used herein, the term "retention and drainage aids" refers to one or more additives to cellulosic suspensions that provide improved retention and/or filtration in cellulosic product manufacturing processes. As used herein, the term "dry strength agent" refers to one or more cellulosic suspension additives that impart improved dry strength to cellulosic products.

The charged aromatic acrylamide-based polymers of the present invention contain one or more charged or ionic groups of the same or different types. The one or more charged groups may be anionic, cationic, or a combination of anionic and cationic groups. In one embodiment of the invention, the polymer contains one or more cationic groups of the same or different type. Alternatively or additionally, the polymer may contain one or more anionic groups of the same or different type. Thus, the charged aromatic acrylamide-based polymer may be selected from anionic, amphoteric and cationic organic polymers. Examples of suitable cationic groups include sulfonium and primary, secondary, tertiary and quaternary ammonium groups, preferably quaternary ammonium groups. Examples of suitable anionic groups include carboxylate, sulfonate, sulfate, phosphate and phosphonate groups.

The charged aromatic acrylamide-based polymers of the present invention contain one or more aromatic groups of the same or different types. Aromatic groups can be present in the polymer backbone (main chain) or in substituents attached to the polymer backbone. Examples of suitable aromatic groups include aryl, aralkyl and alkaryl groups such as phenyl, phenylene, naphthyl, xylylene, benzyl and phenethyl; nitrogen-containing aromatic groups (aryl groups) such as pyridinium and quinolinium; and derivatives of such groups such as benzyl.

The charged aromatic acrylamide-based polymers of the present invention comprise in polymerized form one or more polymerizable acrylamide-based monomers, i.e., acrylamide and/or substituted acrylamides such as methacrylamide, N-alkyl ( Meth)acrylamide, N,N-dialkyl(meth)acrylamide, dialkylaminoalkyl(meth)acrylamide, N,N-methylene-bis(meth)acrylamide, N - Vinyl (meth)acrylamide and N-methallyl (meth)acrylamide. Examples of suitable charged aromatic acrylamide-based polymers of the present invention include polymers obtained by polymerizing a monomer mixture comprising acrylamide or methacrylamide (ie (meth)acrylamide), preferably acrylamide. The monomer mixture may also comprise one or more copolymerizable cationic, anionic and/or nonionic monomers. According to a preferred embodiment, the monomer mixture contains one or more charged aromatic monomers which may be cationic and/or anionic. Alternatively or additionally, the monomer mixture contains anionic and/or cationic monomers and nonionic aromatic monomers.

Examples of suitable cationic aromatic monomers include monomers represented by the general formula (I) as follows:

wherein R ₃ is H or CH ₃ ; R ₁ and R ₂ are each H or preferably a hydrocarbon group, suitably an alkyl group having 1-3, preferably 1-2 carbon atoms; A ₂ is O or NH; B ₂ is An alkyl or alkylene group having 2-8, suitably 2-4 carbon atoms, or a hydroxypropylene group; Q is a substituent containing an aromatic group, which is suitably accessible through A phenyl or substituted phenyl group usually having an alkylene group of 1-3, suitably 1-2 carbon atoms attached to nitrogen, and Q is preferably benzyl (-CH ₂ -C ₆ H ₅ ); and X ^- is an anionic counterion, usually a halide such as chloride. Examples of suitable monomers represented by the general formula (I) include dimethylaminoethyl acrylate benzyl ammonium chloride and dimethylaminoethyl methacrylate benzyl ammonium chloride. Examples of other suitable co-cationic monomers include the acid addition and quaternary ammonium salts of dimethylaminoethyl (meth)acrylate and the diallyldimethylammonium chloride and triallylammonium salts.

Examples of anionic monomers include monomers that provide anions in an aqueous solution. Examples of suitable anionic aromatic monomers include styrene sulfonate and salts thereof, including sodium and other alkali metal salts. Examples of other suitable copolymerizable anionic monomers include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, itaconic acid and maleic acid and their salts, preferably their salts, including sodium and other alkali metal salts.

Examples of suitable nonionic aromatic monomers include styrene, substituted styrenes and divinylbenzene. Examples of other suitable copolymerizable nonionic monomers include acrylate-based monomers such as dialkylaminoalkyl (meth)acrylates, polyethylene glycol di(meth)acrylates, (meth)acrylic acid Glyceryl esters and vinyl amides.

Preferred examples of the charged aromatic acrylamide-based polymer of the present invention include the optional Cationic and amphoteric cationic polymers obtained by polymerization in combination with anionic monomers. Other examples include anionic and amphoteric polymers obtained by polymerizing monomer mixtures comprising (meth)acrylamide and anionic aromatic monomers such as styrene sulfonate and salts thereof, optionally in combination with cationic monomers.

The charged aromatic acrylamide-based polymers of the present invention can generally be prepared from monomer mixtures comprising 1-99 mole %, suitably 2-50 mole %, preferably 5-20 mole % monomers having aromatic groups Monomers such as monomers with aromatic and cationic or anionic groups or monomers with aromatic groups and monomers with cationic or anionic groups and 99-1 mol%, suitably 98-50 mol%, preferably 95 - 80 mole % of other copolymerizable monomers, preferably comprising acrylamide or methacrylamide ((meth)acrylamide), wherein said monomer mixture suitably comprises 98-50 mole %, preferably 95-80 mole % (Meth)acrylamide, the sum of the percentages is 100.

The charged aromatic acrylamide-based polymers of the present invention may be linear, branched or crosslinked. The aramid-based polymer is suitably water-soluble or water-swellable, preferably water-soluble and is preferably added to the cellulosic suspension in the form of an aqueous solution or an aqueous dispersion thereof.

The charged aromatic acrylamide-based polymers of the present invention may have a charge density of from about 0.5 to about 10 meq/g, preferably from about 1 to about 8 meq/g. Examples of aromatic polymers that may be used in accordance with the present invention include those disclosed in WO 2002/12626, 2003/064767, 2006/068576 and 2006/123989, which are incorporated herein by reference.

Charged aramid-based polymers generally have a weight average molecular weight of at least about 50,000 or at least about 100,000, suitably at least about 500,000 or at least about 1,000,000. In most cases, the weight average molecular weight is preferably not greater than about 50 million, especially not greater than about 10 million or about 5 million.

Examples of suitable siliceous materials include anionic silica-based particles and anionic clays of the smectite type. The siliceous material preferably has particles with a particle size in the colloidal range. Preference is given to using anionic silica-based particles, ie particles based on _SiO2 or silicic acid, and such particles are generally supplied in the form of colloidal aqueous dispersions, so-called sols. Examples of suitable silica-based particles include colloidal silica and different types of homo- or co-polymeric polysilicic acids. Silica-based sols may be modified and may contain other elements such as aluminum, boron, nitrogen, zirconium, gallium, titanium, etc., which may be present in the aqueous phase and/or in the silica-based particles. Examples of suitable such silica-based particles include colloidal aluminum-modified silica and aluminosilicates. Mixtures of such suitable silica-based particles may also be used.合适的包含阴离子硅石基颗粒的助滤剂和助留剂的实例包括美国专利号4,388,150；4,927,498；4,954,220；4,961,825；4,980,025；5,127,994；5,176,891；5,368,833；5,447,604；5,470,435；5,543,014；5,571,494；5,573,674；5,584,966；5,603,805 5,688,482 and 5,707,493, which are incorporated herein by reference.

Examples of suitable anionic silica-based particles include those having an average particle size of less than about 100 nm, preferably less than about 20 nm, more preferably from about 1 to about 10 nm. As is customary in silica chemistry, particle size refers to the average size of primary particles, which may be aggregated or non-aggregated. The specific surface area of the silica-based particles is suitably greater than 50 m ² /g, preferably greater than 100 m ² /g. The specific surface area may generally be up to about 1700 m ² /g, preferably up to 1000 m ² /g. The specific surface area is measured in a well-known manner by titration with NaOH, for example as described in GWSears, Analytical Chemistry 28 (1956): 12, 1981-1983 and US Pat. No. 5,176,891. Therefore, the obtained area represents the average specific surface area of the particles.

The anionic silica-based particles preferably have a specific surface area of 50-1000 m ² /g, more preferably 100-950 m ² /g. Sols of these types of silica-based particles, for example, also include modifications with any of the aforementioned elements. The silica-based particles preferably have an S value of 8-50%, preferably 10-40%, and contain a specific surface area of 300-1000m ² /g, suitably 500-950m ² /g, preferably 750-950m ² /g of silica-based The particles are present in a sol, which can be modified as described above. The S value can be measured and calculated as described in Iler & Dalton, J. Phys. Chem. 60 (1956), 955-957. The S value indicates the degree of aggregation or microgel formation and a lower S value indicates a higher degree of aggregation.

In yet another preferred embodiment of the present invention, the silica-based particles are selected from homo- or co-polymeric polysilicic acids having a high specific surface area, suitably greater than about 1000 m ² /g. The specific surface area may be 1000-1700 m ² /g, preferably 1050-1600 m ² /g. The sol of modified or copolymerized polysilicic acid may contain other above-mentioned elements. In the prior art, polysilicic acid is also referred to as polysilicic acid, polysilicic acid microgel, polysilicate, and polysilicate microgel, all of which are included in the term polysilicic acid as used herein. Such aluminum-containing compounds are also commonly referred to as polyaluminosilicates and polyaluminosilicate microgels, and are included within the terms colloidal aluminum-modified silica and aluminosilicate as used herein.

Examples of suitable anionic clays of the smectite type include montmorillonite/bentonite, hectorite, beidellite, nontronite, saponite, hectorite, preferably bentonite. Examples of suitable anionic bentonites include those disclosed in US Patent Nos. 4,753,710; 5,071,512 and 5,607,552, which are incorporated herein by reference.

Examples of suitable cationic flocculants (also known as litter catchers and fixatives) include water-soluble organic polymer flocculants and inorganic flocculants. Cationic flocculants can be used alone or together, that is, polymer flocculants can be used in combination with inorganic flocculants. Examples of suitable water-soluble organic polymer cationic flocculants include cationic polyamines, polyamidoamines, polyethyleneimines, polycondensates of dicyandiamide and water-soluble ethylenically unsaturated monomers or 50-100 mole % cationic monomers A polymer of a monomer blend formed with 0-50 mole % of other monomers. The amount of cationic monomer is usually at least 80 mole percent, suitably 100 mole percent. Examples of suitable ethylenically unsaturated cationic monomers include dialkylaminoalkyl (meth)acrylates and dialkylaminoalkyl (meth)acrylamides, preferably in quaternized form, and diallyldioxane Ammonium chlorides such as diallyldimethylammonium chloride (DADMAC), preferably homopolymers and copolymers of DADMAC. The organic polymer cationic flocculant generally has a weight average molecular weight of 1,000-700,000, suitably 10,000-500,000. Examples of suitable inorganic flocculants include aluminum compounds such as alum and polyaluminum compounds such as polyaluminum chloride, polyaluminum sulfate, polyaluminum silicate sulfate and mixtures thereof.

Examples of other organic polymers useful as drainage and retention aids include polymers of the type described above, except that one or more aromatic groups need not be present in the polymer. Examples of such suitable organic polymers include anionic, amphoteric and cationic polysaccharides such as guar gum and starch; anionic, amphoteric and cationic vinyl addition polymers such as acrylamide based polymers such as substantially linear, branched and Linked anionic and cationic acrylamide based polymers, preferably cationic starch and cationic and anionic polyacrylamide.

According to the invention, the cellulosic product is preferably sized with a hydrophobic sizing agent which is added to the pulp and/or applied to the surface of the cellulosic product prior to dewatering, preferably at least for sizing the pulp. In multilayer cellulosic products, it is preferred to size one or more layers comprising thermoplastic microspheres and aromatic polymer. The sized cellulose products of the present invention exhibit increased resistance to penetration by aqueous fluids and significantly increased resistance to edge wicking. Preferred sizing agents include cellulosic reactive sizing agents such as ketene dimers or polymers such as alkyl or alkenyl ketene dimers (AKD), succinic anhydrides such as alkyl or alkenyl succinic anhydrides (ASA) and mixtures thereof. Other useful sizing agents include cellulosic non-reactive sizing agents such as rosin, starch, and other polymeric sizing agents such as copolymers of styrene with vinyl monomers such as maleic anhydride, acrylic acid and its esters, acrylamide, and the like. The same or different sizing agents can be used in different layers of the cellulosic product. For example, AKD or ASA may be used in one or more layers and rosin in one or more other layers.

Preferred ketene dimers have the general formula (II):

Wherein R ¹ and R ² represent the same or different saturated or unsaturated hydrocarbon groups such as alkyl, alkenyl, cycloalkyl, aryl or aralkyl. The hydrocarbyl group may be branched or straight chain and preferably has 6-36, most preferably 12-20 carbon atoms. Examples of hydrocarbyl groups include branched and straight chain octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, behenyl, tetradecyl, Alkyl, phenyl, benzyl, beta-naphthyl, cyclohexyl and hexadecyl. Depending on the hydrocarbyl group, the ketene dimer can be solid or liquid at room temperature (25°C). Examples of suitable sizes and formulations thereof include those disclosed in US Patent Nos. 5,969,011; 6,165,259; 6,306,255 and 6,846,384.

According to the invention, the cellulosic product preferably comprises a wet strength agent which is added to the pulp prior to dewatering. Suitable wet strength agents include polyamine-epihalohydrin resins, polyamide-epihalohydrin resins, polyaminoamide-epihalohydrin resins, urea-formaldehyde resins, urea-melamine/formaldehyde resins, phenolic resins, poly Acrylamide-glyoxal condensate resins, polyvinylamine resins, polyurethane resins, polyisocyanate resins and mixtures thereof, among which polyaminoamide-epichlorohydrin resins are particularly preferred.

It is particularly preferred that at least one sizing agent, preferably a ketene dimer, and a wet strength agent, preferably a polyaminoamide-epihalohydrin resin, be added to the pulp during the production of paper or board.

Cellulosic products may also contain other additives commonly used in papermaking and added to cellulosic suspensions prior to dewatering. Such additives may include one or more fillers, for example mineral fillers such as kaolin, clay, titanium dioxide, gypsum, talc, chalk, ground marble, ground calcium carbonate and precipitated calcium carbonate. Other common additives may include dyes, optical brighteners, and the like.

According to the invention, cellulosic products such as single-ply and ply paper and board grades can be subjected to further process steps. Examples of suitable process steps include coating such as starch coating and pigment coating, printing and cutting. Thus, examples of suitable cellulosic products according to the invention include coated boards such as starch and/or pigment coated boards and printed boards.

Thermoplastic microspheres, charged aramid-based polymers and optionally other additives such as siliceous materials, flocculants, other organic polymers, sizing agents and wet strength agents may be added to the cellulose suspension in a conventional manner and in any order in the liquid. Preferably, the thermoplastic microspheres are added preferably before the charged aramid-based polymer (although the reverse order or reverse addition can also be used) and preferably before the siliceous material, sizing agent and wet enhancer (if used) are added in the cellulose suspension. When a siliceous material is used, preferably the charged aromatic acrylamide-based polymer is added to the cellulosic suspension prior to or simultaneously with the addition of the siliceous material. It is also preferred to add the cationic polymer before a shear segment which may be selected from pumping, mixing, cleaning, etc. and to add the siliceous material after this shear segment. Where cationic flocculants are used, they are preferably introduced into the cellulosic suspension, preferably early in the process, before the charged aromatic acrylamide-based polymer and siliceous material, if used, are introduced. When a sizing agent is used, it is preferably introduced into the cellulosic suspension early in the process, eg before the addition of the thermoplastic microspheres. When wet strengthening agents are used, they are preferably introduced into the cellulosic suspension early in the process, usually before the sizing agent is added and before or after the thermoplastic microspheres are added.

According to the present invention, thermoplastic microspheres, charged aramid-based polymers and optionally other additives can be produced in a wide range of A range of varying amounts is added to the cellulosic suspension or present in the cellulosic product. The amount of thermoplastic microspheres is suitably from about 1 to about 100 kg/ton, preferably from about 1 to about 50 kg/ton, most preferably from about 4 to about 40 kg/ton of dry cellulosic suspension or product. The amount of charged aromatic acrylamide-based polymer is suitably from about 0.01 to about 30 kg/ton, preferably from about 0.1 to about 5 kg/ton of dry cellulosic suspension or product. The amount of siliceous material (if used) is suitably from about 0.01 to about 10 kg/ton, preferably from about 0.1 to about 5 kg/ton of dry cellulosic suspension or product. The amount of cationic flocculant, if used, is suitably from about 0.01 to about 30 kg per tonne, preferably from about 1 to about 20 kg tonne of dry cellulosic suspension or product. The amount of other organic polymers, if used, is suitably from about 0.01 to about 30 kg/ton, preferably from about 0.1 to about 5 kg/ton of dry cellulosic suspension or product. The amount of sizing agent (if used) is suitably from about 0.1 to about 10 kg/ton, preferably from about 0.3 to about 5 kg/ton of dry cellulosic suspension or product. The amount of wet strength agent (if used) is suitably from about 0.1 to about 10 kg/ton, preferably from about 0.5 to about 5 kg/ton of dry cellulosic suspension or product.

The invention is further illustrated in the following examples, without however restricting the invention. Unless otherwise stated, parts and percentages refer to parts and percentages by weight, respectively.

Example 1

The following products were used in the examples:

MS 1 : Unexpanded microspheres (Expancel ^™ 820SL80) with an average particle size of 16-24 μm.

MS 2: Unexpanded microspheres (Expancel ^™ 461WU20) with an average particle size of 6-9 μm.

MS 3: Partially pre-expanded microspheres (Expancel ^™ 461WE20) with an average particle size of 20-30 μm.

PL 1: Cationic acrylamide-based polymer prepared by polymerizing acrylamide (90 mole %) and acryloyloxyethyltrimethylammonium chloride (10 mole %), wherein the polymer has about 6 million The weight average molecular weight and cationic charge of about 1.2meq/g.

PL 2: A cationic acrylamide-based polymer prepared by polymerizing acrylamide (90 mole %) and acryloyloxyethyldimethylbenzyl ammonium chloride (10 mole %), wherein the polymer has about 6 A weight average molecular weight of one million and a cationic charge of about 1.2 meq/g.

PL 3: A cationic polyacrylamide-based polymer prepared by polymerizing acrylamide (90 mole %) and acryloyloxyethyldimethylammonium chloride (10 mole %), wherein the polymer has about 1 The weight average molecular weight of 10,000 and the cationic charge of about 1.2meq/g.

PL 4: A cationic polyacrylamide-based polymer prepared by polymerizing acrylamide (90 mole %) and acryloyloxyethyltrimethylbenzyl ammonium chloride (10 mole %), wherein the polymer has about A weight average molecular weight of 1 million and a cationic charge of about 1.2 meq/g.

NP 1: Anionic inorganic silicic acid polycondensate in the form of a colloidal aluminum-modified silica sol with an S value < 35 and containing silica-based particles with a specific surface area of about 700 m ² /g.

ST 1: A cationic starch-based biopolymer modified with 2,3-hydroxypropyltrimethylammonium chloride according to D.S.0.042, wherein the polymer has a cationic charge density of about 0.28 meq/g.

SA 1: AKD sizing, stabilized with PL 3.

Example 2

A liquid packaging paperboard interlayer having a grammage of about 200 gsm was produced on a PFI sheet former. The pulp used in the tests was based on 100% bleached softwood kraft fibers. The pulp consistency was 1.8%. The conductivity is 0.2 mS/cm.

Incorporate in the pulp at the following times (seconds):

ο0 sec, Expancel ^™ microspheres, MS 1

ο15 sec, cationic polymer, PL

ο30 seconds, anionic silica sol, NP 1

ο 45 seconds, dehydration

Press and dry the cardboard sheet. To expand the microspheres MS, a drum dryer at 125° C. was used.

丹麦提供的Bendtsen孔率检验器模型5测量。该孔率检验器单位为[ml/min]空气。以单位[cm³/kg]度量的体积通过厚度[μm]除以克重[g/m²]来计算。根据Lorentzen & Wettre，瑞典提供的L&W检验器类型5102测量厚度并且在纸或纸板样品的给定面积[m²]下通过使用标准等级给出重量[g]来测量克重。Porosity by Andersen &

Bendtsen Porosity Tester Model 5 provided by Denmark for measurement. The unit of the porosity tester is [ml/min] air. The volume measured in the unit [cm ³ /kg] is calculated by dividing the thickness [μm] by the grammage [g/m ² ]. The L&W tester type 5102 supplied by Lorentzen & Wettre, Sweden measures the caliper and the grammage by giving the weight [g] using standard scales at a given area [m ² ] of a paper or board sample.

Table 1 shows the results of porosity and volume measurements at different additions, calculated as dry product and based on a dry pulp system, with only silica-based particles calculated as _SiO2 and based on a dry pulp system.

Test Nos. 1-5 illustrate the method using additives for comparison (reference) and Test Nos. 6-8 illustrate the inventive method.

Table 1:

test number Expancel ^TM Microsphere MS 1(kg/t) Polymer type Polymer (kg/t) Nanoparticles NP 1(kg/t) Volume (cm ³ /g) Porosity (ml/min) 1 - - - - 2.1 328 2 - - - 0.5 2.2 385 3 10 PL 1 0.5 0.5 2.4 558 4 20 PL 1 0.5 0.5 2.7 742 5 40 PL 3 2 2 3.1 1010 6 10 PL 2 0.5 0.5 2.4 532 7 20 PL 2 0.5 0.5 2.7 703 8 40 PL 4 2 2 3.1 933

It can be seen from Table 1 that by using PL 2 and PL 4 according to the invention, the volume increases at lower porosities than when using PL 1 and PL 3.

Example 3

A liquid packaging board interlayer was produced on a PFI sheet former according to the general procedure of Example 2, except that the conductivity was adjusted to 3.0 mS/cm by adding _CaCl2 .

Table 2 shows the results where Test Nos. 1-2 illustrate the method using the additive for comparison (reference) and Test No. 3 illustrates the method of the invention.

Table 2:

test number Expancel ^TM Microsphere MS 1(kg/t) Polymer type Polymer (kg/t) Nanoparticles NP 1(kg/t) Volume (cm ³ /g) Porosity (ml/min) 1 - - - - 2.2 337 2 20 PL 3 2 0.5 2.6 718 3 20 PL 4 2 0.5 2.6 668

As can be seen from Table 2, the present invention provides cellulose products with improved (lower) porosity.

Example 4

Liquid packaging paperboard interlayers having a grammage of about 120 gsm were produced in a laboratory paper machine (XPM). The pulp used in the tests was based on 100% unbleached chemical thermally refined pulp (CTMP). The pH is 8.0.

Add to the pulp in the following order:

ο Cationic starch 1, ST 1, 50%

o Expancel ^™ microspheres, MS

ο Cationic starch 2, ST 1, 50%

ο AKD sizing agent, SA 1

ο cationic polymer, PL

ο anionic silica sol, NP 1

The web samples were dried as they exited the XPM (maximum drying temperature 100°C). The microspheres were expanded at 140°C in a drum dryer.

Table 3 shows the results where Test Nos. 1-2 illustrate the method using additives for comparison (reference) and Test Nos. 3-4 illustrate the method of the invention.

table 3:

test number Cationic starch ST 1(kg/t) Sizing agent SA 1(kg/t) Expancel ^TM microspheres (kg/t)/type Polymer (kg/t)/type Nanoparticles NP 1(kg/t) Volume (cm ³ /g) Porosity (ml/min) 1 3+3 2 40/MS 2 0.15/1 3 3.0 2458 2 3+3 2 40/MS 3 0.15/1 3 4.1 2625 3 3+3 2 40/MS 2 0.15/2 3 3.0 2417 4 3+3 2 40/MS 3 0.15/2 3 4.1 2617

As can be seen from Table 3, the present invention provides cellulose products with improved (lower) porosity.

Claims (29)

1. cellulose products that contains preparatory expanded thermoplastic microspheres and charged aromatic acrylamide-based polymer.

2. according to the cellulose products of claim 1, wherein said charged aromatic acrylamide-based polymer is water miscible.

3. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer is cationic.

4. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer is both sexes.

5. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer contains quaternary ammonium group.

6. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer obtains through the monomer mixture polymerization that makes the CATION aromatic monomer or comprise the CATION aromatic monomer of following universal architecture formula (I) expression:

R wherein ₃Be H or CH ₃R ₁And R ₂H or have the alkyl of 1-3 carbon atom respectively does for oneself; A ₂Be O or NH; B ₂Be alkyl or alkylidene with 2-8 carbon atom, or hydroxy propylidene; Q is a benzyl; And X ^-Be anionic counter-ion.

7. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer is anionic.

8. according to the cellulose products of claim 2, wherein said charged aromatic acrylamide-based polymer has the weight average molecular weight greater than 500,000.

9. according to the cellulose products of claim 2, wherein said cellulose products is paper or cardboard.

10. according to the cellulose products of claim 2, wherein sizing agent further is present in the cellulose products, adds in the cellulose suspension or puts on the cellulose products surface.

11. according to the cellulose products of claim 2, wherein siliceous material further is present in the cellulose products or adds in the cellulose suspension.

12. according to the cellulose products of claim 2, wherein wet strength agent further is present in the cellulose products or adds in the cellulose suspension.

13. according to the cellulose products of claim 2, wherein said cellulose products is a couch board.

14. according to the cellulose products of claim 2, wherein said cellulose products contains the cellulose fibre of 50 weight % at least based on dry.

15. the method for a production of cellulose product, it comprises:

(i) aqueous suspension of cellulose fiber is provided;

(ii) preparatory expanded thermoplastic microspheres and charged aromatic acrylamide-based polymer are added in the said suspension; And

(iii) gained suspension is dewatered.

16. according to the method for claim 15, wherein said charged aromatic acrylamide-based polymer is water miscible.

17. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer is cationic.

18. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer is both sexes.

19. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer contains quaternary ammonium group.

20. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer obtains through the monomer mixture polymerization that makes the CATION aromatic monomer or comprise the CATION aromatic monomer of following universal architecture formula (I) expression:

R wherein ₃Be H or CH ₃R ₁And R ₂H or have the alkyl of 1-3 carbon atom respectively does for oneself; A ₂Be O or NH; B ₂Be alkyl or alkylidene with 2-8 carbon atom, or hydroxy propylidene; Q is a benzyl; And X ^-Be anionic counter-ion.

21. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer is anionic.

22. according to the method for claim 16, wherein said charged aromatic acrylamide-based polymer has the weight average molecular weight greater than 500,000.

23. according to the method for claim 16, wherein said cellulose products is paper or cardboard.

24. according to the method for claim 16, wherein sizing agent further is present in the cellulose products, adds in the cellulose suspension or puts on the cellulose products surface.

25. according to the method for claim 16, wherein siliceous material further is present in the cellulose products or adds in the cellulose suspension.

26. according to the method for claim 16, wherein wet strength agent further is present in the cellulose products or adds in the cellulose suspension.

27. according to the method for claim 16, wherein said cellulose products is a couch board.

28. according to the method for claim 16, wherein said cellulose products contains the cellulose fibre of 50 weight % at least based on dry.

29. according to each cellulose products among the claim 1-14 as the purposes of flexible package punch cardboard.