Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/02—Compounds of alkaline earth metals or magnesium
  • C09C1/021—Calcium carbonates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
  • D21H17/69—Water-insoluble compounds, e.g. fillers, pigments modified, e.g. by association with other compositions prior to incorporation in the pulp or paper
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/14—Pore volume

Definitions

• the invention relates to aqueous slurries of finely divided fillers which are at least partially coated with polymers, processes for their preparation and their use as additives to the pulp in the manufacture of filler-containing paper, filler-containing cardboard and filler-containing cardboard.
• aqueous suspensions of inorganic particles which have a positive zeta potential are mixed with an anionic latex of a resin, the balance of the negative and positive charges of the particles of the inorganic substance in the suspension and the resin in the latex during mixing is adjusted such that essentially all of the resin particles are bound to the surface of the particles of the inorganic substance and the coated particles thus obtained have a zeta potential of essentially zero.
• Treatment of the inorganic particles with a latex presupposes that the inorganic particles are pretreated with a cationic agent, such as cationic starch, so that they have a positive zeta potential.
• the aqueous suspensions are added to the paper stock in the manufacture of filler-containing paper.
• a dispersing agent e.g. low molecular weight polyacrylic acids, cf. EP-A-0 002 771.
• the dispersed pigment particles have an anionic surface charge.
• the aqueous pigment slurries are used, for example, in the manufacture of paper.
• EP-B-0 573 458 discloses a process for the preparation of aqueous slurries of finely divided fillers, which are at least partially coated with polymers, for the production of filler-containing papers.
• a cationic strengthener for paper is added to an aqueous slurry of fillers and then a nonionic and / or anionic strengthener for paper or a nonionic or anionic sizing agent for paper.
• the cationic feedstocks are always used in such an amount that the finely divided fillers carry a cationic charge.
• DE-A-198 21 089 discloses another process for the preparation of aqueous slurries of finely divided fillers which are at least partially coated with polymers.
• an aqueous suspension of fillers is treated in the absence of cationic strengthers for paper with at least one polymeric agent in the form of an aqueous dispersion.
• such dispersions always contain polymeric emulsifiers, e.g. degraded starches or synthetic polymers.
• the object of the invention is to provide further aqueous suspensions of finely divided fillers which, in papermaking, produce papers with improved tear length and printability compared to the known suspensions.
• Slurries of finely divided fillers which are at least partially coated with polymers the slurries being obtainable by treating aqueous slurries of finely divided fillers with at least one binder for paper coating slips.
• the aqueous slurries contain, for example, 1 to 50% by weight, preferably 10 to 40% by weight, of at least one finely divided filler.
• the amount of binder is, for example, 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on fillers.
• the invention also relates to a process for the preparation of the aqueous slurries, 0.1 to 5% by weight of at least one binder for paper coating slips, based on filler, being added to an aqueous slurry of at least one finely divided filler, or the aqueous slurry of at least one finely divided Filler in an aqueous dispersion of a binder for paper coating colors and mixes the components.
• the molar mass of the emulsifiers contained in the binders for paper coating colors is ⁇ 2000.
• Another object of the invention is the use of the aqueous slurries described above as an additive to the pulp in the production of filler-containing paper, filler-containing like cardboard or filler-containing cardboard by dewatering the paper stock.
• fillers e.g. Calcium carbonate, which can be used in the form of lime, chalk, marble or precipitated calcium carbonate, talc, kaolin, bentonite, satin white, calcium sulfate, barium sulfate and titanium dioxide.
• the particle diameter of the finely divided fillers is, for example, between 10 40 and 90% less than 2 ⁇ m.
• the fillers are processed, for example, by introducing them into water to form an aqueous slurry.
• Precipitated calcium carbonate is usually used in the absence of
• an anionic dispersing agent e.g. Polyacrylic acids with a molecular weight Mw of, for example, 1000 to 40,000. If an anionic dispersant is used,
• the finely divided fillers dispersed in water in the presence of anionic dispersants are anionic.
• the aqueous slurries usually contain at least 15 to 25% by weight
• aqueous slurries of finely divided fillers are treated with at least one binder for paper coating slips.
• a binder for paper coating slips can be added to an aqueous slurry containing at least 1 to 50% by weight of a finely divided filler, or an aqueous slurry of a 5 finely divided filler in an aqueous dispersion Enter a binder for paper coating colors and mix the components.
• the treatment of the aqueous slurries of finely divided fillers with the binders for paper coating colors can be carried out continuously or batchwise.
• the fillers are at least partially coated or impregnated with binders.
• the components are mixed, for example, in a shear field. In most cases it is sufficient to stir the components after they have been brought together or to treat them in a shear field of an Ultraturrax device. Bringing together and mixing the components of the aqueous slurries can take place, for example, in the temperature range from 0 ° C. to 95 ° C., preferably 10 to 70 ° C. The components are usually mixed at room temperature up to a temperature of 40 ° C.
• the pH of the aqueous slurries of fillers treated with coating color binders is, for example, 5 to 11, preferably 6 to 9, the pH of slurries containing calcium carbonate preferably being more than 6.5.
• the binders preferably contain so-called main monomers copolymerized, selected from Ci to Cie alkyl (meth) acrylates, vinyl aromatics with up to 20 C atoms, vinyl esters of carboxylic acids with 1 to 20 C atoms, vinyl halides, ethylenically unsaturated nitriles, non-aromatic hydrocarbons with a or two conjugated double bonds or mixtures of these monomers.
• main monomers copolymerized selected from Ci to Cie alkyl (meth) acrylates, vinyl aromatics with up to 20 C atoms, vinyl esters of carboxylic acids with 1 to 20 C atoms, vinyl halides, ethylenically unsaturated nitriles, non-aromatic hydrocarbons with a or two conjugated double bonds or mixtures of these monomers.
• (Meth) -acrylklarealkylestern with a C ⁇ -C ⁇ o-alkyl radical such as methyl methacrylate, methyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
• a C ⁇ -C ⁇ o-alkyl radical such as methyl methacrylate, methyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
• Mixtures of the (meth) acrylic acid alkyl esters are also particularly suitable.
• the vinyl esters of carboxylic acids with 1 to 20 carbon atoms are, for example Vinyl laurate, vinyl stearate, vinyl propionate and vinyl acetate.
• Suitable vinylaromatic compounds with up to 20 carbon atoms are vinyltoluene, ⁇ -butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene.
• Examples of ethylenically unsaturated nitriles are acrylonitrile and methacrylonitrile.
• Vinyl halides are ethylenically unsaturated compounds substituted with chlorine, fluorine or bromine, preferably vinyl chloride and vinylidene chloride.
• butadiene, isoprene and chloroprene and ethylene may be mentioned as non-aromatic hydrocarbons with one or two conjugated olefinic double bonds.
• the binders can optionally also contain other monomers in copolymerized form, for example monomers containing hydroxyl groups, such as hydroxyalkyl acrylates or monomers with alkoxy groups, as can be obtained by alkoxylating hydroxyl-containing monomers with alkoxides, in particular ethylene oxide or propylene oxide, monomers with acid or Anhydride groups or their salts, for example (meth) acrylic acid, maleic acid, vinyl sulfonic acid.
• the binders preferably consist of a polymer which contains at least 20% by weight of the main monomers, particularly preferably at least 35% by weight and very particularly preferably at least 50% by weight, of at least one main monomer.
• the binder can also contain at least 1% by weight, particularly preferably at least 3% by weight, particularly preferably at least 15% by weight, of monomers copolymerized with at least one acid group (acid monomers for short).
• the acid groups of the polymer can, if appropriate, be at least partially neutralized before later use. Preferably at least 30 mol%, particularly preferably 50 to 100% of the acid groups are neutralized.
• Suitable bases are volatile bases such as ammonia or non-volatile bases such as alkali metal hydroxides, in particular sodium hydroxide solution.
• Preferred binders are, for example, aqueous dispersions of copolymers
• binders are polymers of (a) styrene, (b) butadiene and (c) optionally acrylic acid or methacrylic acid. Copolymers based on (meth) acrylic esters or vinyl acetate and other monoethylenically unsaturated monomers are also of interest as binders for paper coating slips for the treatment of aqueous slurries of fillers.
• the glass transition temperature of the polymers is e.g. -40 to + 50 ° C and is preferably below 6 ° C.
• the binders for paper coating slips are preferably prepared by free-radical polymerization of the above-mentioned monomers in an aqueous medium in the presence of protective colloids or emulsifiers.
• Suitable protective colloids are, for example, polyvinyl alcohols or partially hydrolyzed polyvinyl acetates.
• Aqueous dispersions of the binders which contain anionic emulsifiers such as sodium lauryl sulfate, disulfo-C 1 -alkyldiphenyl oxide or mixtures thereof as emulsifiers for the polymers are particularly preferred.
• anionic emulsifiers such as sodium lauryl sulfate, disulfo-C 1 -alkyldiphenyl oxide or mixtures thereof as emulsifiers for the polymers are particularly preferred.
• Common emulsifiers are, for example, ethoxylated fatty alcohols (degree of ethoxylation: 3 to 50, alkyl radical: C ⁇ - to C 36 ) / ethoxylated mono-, di- and trialkylphenols (degree of ethoxylation: 3 to 50, alkyl radical: C ⁇ - to C ⁇ 2 ), alkali metal salts of Dialkyl esters of sulfosuccinic acid as well as alkali and ammonium salts of alkyl sulfates (alkyl radical: CQ to C 2 ), of ethoxylated alkanols (degree of ethoxylation: 4 to 30, alkyl radical: C 2 to Ci 6), of ethoxylated alkyl phenols (degree of ethoxylation: 3 to 50, alkyl radical : C to Cg), of alkylsulfonic acids (alkyl radical: C ⁇ to Cia) and of alkylarylsulf
• Aqueous slurries of precipitated calcium carbonate, which is free from dispersants, and of ground calcium carbonate, which can be obtained by grinding lumpy calcium carbonate or marble in the presence of anionic polymeric dispersants such as polyacrylic acids with molecular weights of 1000 to 15000, are particularly preferably prepared.
• Anionic aqueous dispersions of copolymers based on styrene and butadiene or styrene and acrylic esters which are stabilized with the aid of emulsifiers which have a molecular weight M w ⁇ 2000 are preferably used as binders for this purpose.
• the aqueous slurries of fillers produced in accordance with the invention are used as additives to the paper stock in the production of filler-containing paper, filler-containing cardboard or filler-containing cardboard by dewatering the paper stock. They can be stored for a longer period of time or can be prepared and processed directly in the paper mill immediately before paper production. They are added to the paper stock in such an amount that filler-containing papers are formed which contain, for example, 5 to 50% by weight, preferably 15 to 35% by weight, of filler.
• the aqueous slurries are particularly suitable for the production of papers with filler contents of 30 to 50% by weight.
• the aqueous slurries of fillers can be added to both the thick and the thin material in papermaking.
• the aqueous pigment slurries treated according to the invention with a binder for paper coating slips can be used for the production of all filler-containing paper grades, for example newspaper printing, SC paper (supercalendered paper), wood-free or wood-containing writing and printing papers.
• the main raw material components are wood pulp, thermomechanical material (TMP), che thermomechanical material (CTMP), pressure grinding (PGW) and sulphite and sulphate pulp.
• TMP thermomechanical material
• CMP che thermomechanical material
• PGW pressure grinding
• sulphite and sulphate pulp sulphate pulp.
• the retention aids can, for example, be added to the thick stock or also to the thin stock.
• the retention agent used is, for example, high molecular weight polyacrylamides (the molar masses of the polymers are above 2 million) or so-called microparticle systems are used, in which case a polymeric cationic retention agent is first added to the paper stock, the paper stock is then subjected to shear and then bentonite or finely divided silica is added Amounts up to 2% by weight, based on dry fiber, are added.
• optical brighteners can also be added to the paper stock.
• the amounts of optical brighteners are, for example, 0.3 to 3.0, preferably 0.6 to 1.5% by weight, based on dry paper stock.
• aqueous filler slurries Due to the treatment of the aqueous slurries of finely divided fillers with aqueous dispersions of binders for paper coating colors, aqueous filler slurries are obtained which can be processed into papers in which the dusting in the printing and copying process is reduced compared to filler-containing papers whose fillers have not been treated with a binder were.
• aqueous slurries of fillers produced in Examples 1 to 5 and in Comparative Example 1 were then tested for their suitability for the production of filler-containing papers.
• the particle size of the dispersed fillers was ⁇ 2 ⁇ m in the examples and in comparative example 1 for 90% of the particles. example 1
• 0.6 g of a 50% commercially available aqueous dispersion of a copolymer based on styrene and n-butyl acrylate stabilized with anionic emulsifiers and having a glass transition temperature of 5 ° C. (Acronal® S 504) were placed in a beaker and then poured into drinking water diluted a solids content of 10%. Then 150g of a 20% slurry of PCC in water was added to this solution. During the addition of the PCC slurry and thereafter, the mixture was stirred at 1000 rpm using a medicinal stirrer. The pH of the mixture was then adjusted to 8.5.
• 0.6 g of a 50% commercially available, aqueous styrene-butadiene dispersion (Styronal® 8736) containing an anionic emulsifier and having a glass transition temperature of 5 ° C. were placed in a beaker and then diluted with drinking water to a solids content of 10%. Then 150 g of a 20% aqueous PCC slurry were added to this solution. During the addition of the slurry and afterwards, the mixture was Stirrer stirred at 1000 rpm. The pH of the mixture was then adjusted to 8.5.
• TMP thermo-mechanical pulp
• wood pulp was whipped in a ratio of 70/30 at a solids concentration of 4% in the laboratory pulper until a grind of 60-65 was reached.
• the pH of the substance was in the range between 7 and 8.
• the ground substance was then diluted with drinking water to a solids concentration of 0.35%.
• Sheets were also made using the 20% aqueous slurries of precipitated calcium carbonate (PCC slurry) and ground calcium carbonate (GCC slurry) shown in Table 1.
• PCC slurry precipitated calcium carbonate
• GCC slurry ground calcium carbonate
• the paper sheets were each produced on a Rapid-Köthen sheet former according to ISO 5269/2 with a sheet weight of 80g / m2 and then dried for 7 minutes at 90 ° C and then calendered with a line pressure of 200 N / cm.
• the dry tear length of the leaves was tested according to DIN 54540 and the porosity of the leaves according to Bendtsen (ISO 5636-3).
• the dry pick resistance of the papers was determined with the IGT printability tester (ISO 3783).
• the drop-away impact test which is a measure of the water absorption behavior, was carried out on paper samples with a size of 50 x 50 mm. The samples were separated from each other and kept in the climatic room for at least 8 hours (normal climate for pretreatment and testing according to ISO 187). The sample to be tested is placed on the edge of a beaker. 5 ⁇ l of completely demineralized water is added dropwise to the paper surface with the aid of a syringe, and the drops should not fall onto the paper surface. At the same time, a stopwatch is started and the time is measured until the water level of the drop is no longer visible on the paper surface.
• filler-containing papers can be significantly improved in their strength properties both with anionically dispersed GCC slurries and with PCC slurries, which have each been treated with a coating color binder, without the porosity and water absorption behavior of the papers being significantly influenced become.

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Citations (6)

• 2002
  • 2002-03-05 DE DE2002109448 patent/DE10209448A1/de not_active Withdrawn
• 2003
  • 2003-02-28 WO PCT/EP2003/002043 patent/WO2003074786A2/de not_active Application Discontinuation
  • 2003-02-28 AU AU2003215608A patent/AU2003215608A1/en not_active Abandoned

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