Classifications

• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/58—Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof

Definitions

• the pigment lines produced in this way have an insufficient printability in gravure printing, which manifests itself in the fact that the gravure printing ink, especially in the semitones, is not transferred to the stitch sufficiently uniformly, and so-called “missing dots” occur in the print.
• DE-C-1 258 721 discloses binder mixtures for neutral or alkaline paper coating slips based on aqueous dispersions.
• emulsion copolymers A which contain 40 to 70 parts by weight of styrene, 30 to 60 parts by weight of an ester of acrylic or methacrylic acid with alcohols which contain 2 to 12 carbon atoms in the chain, and optionally up to 10 parts of other ethylenically unsaturated consist of copolymerizable compounds and an emulsion copolymer B of 15 to 55 percent by weight acrylic and / or methacrylic acid, optionally up to 10 percent by weight acrylic and / or methacrylamide and 85 to 45 percent by weight other monomers which form water-insoluble homopolymers, of which at least 20 percent by weight, based on these are hydrophobic monomers, esters of acrylic acid or methacrylic acid with alcohols containing 1 to 4 carbon atoms.
• the binder mixture contains 5 to 40 parts by weight of at least one copolymer B and 95 to 60 parts by weight of at least one copolymer A.
• the paper coating colors which are produced using these binder mixtures meet the processing requirements, but no longer meet the increased demands on the printability of them coated papers in rotogravure.
• the object of the invention is to provide a binder which, in comparison to known binders, can be used in a smaller amount for the preparation of paper coating slips and which results in coated papers which, particularly in magazine gravure printing, result in a better print loss.
• the copolymer A of the binder mixture contains, as an essential component, acrylic acid esters with monohydric alcohols which have 2 to 8 carbon atoms. Specifically, these are, for example, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-, iso- and / or tert-butyl acrylate and 2-ethylhexyl acrylate. Those acrylic acid esters which are derived from isobutanol and n-butanol are preferably used to construct copolymers A.
• copolymer A up to 50% by weight of the esters of acrylic acid and monohydric C 2 -C 8 -alcohols can be replaced by methyl acrylate and / or by esters of methacrylic acid and monohydric C 2 -C 8 -alcohols.
• the acrylic acid esters make up 80 to 96, preferably 80 to 90 percent by weight of the emulsion copolymers A.
• the copolymers A contain, as a further constituent, a monomer from the group styrene, methyl methacrylate or acrylonitrile. These monomers make up 0 to 19.5, preferably 3 to 15 percent by weight of the copolymers A.
• Another essential component of the copolymers A are water-soluble homopolymers forming monomers. It is e.g. B. to ethylenically unsaturated C 3 - to C s carboxylic acids, such as acrylic acid, methacrylic acid, maleic acid or crotonic acid, the corresponding acid amides of the ethylenically unsaturated carboxylic acids, for. B. acrylamide and methacrylamide, half esters and half amides of maleic acid and strongly acidic monomeric compounds such as vinylsulfonic acid, styrene-p-sulfone acid, acrylamidopropanesulfonic acid, and sodium vinyl sulfonate.
• carboxylic acids such as acrylic acid, methacrylic acid, maleic acid or crotonic acid
• the corresponding acid amides of the ethylenically unsaturated carboxylic acids for. B. acrylamide and methacrylamide, half esters and half amides of male
• the copolymer A preferably contains 1.0 to 5% of the water-soluble homopolymers forming monomers, of which acrylic acid, acrylamide and methacrylamide or mixtures thereof are preferably used.
• the glass transition temperature of copolymer A can be between -20 and + 10 ° C. (For the definition of the glass transition temperature see P. J. Flory, Principles of Polymer Chemistry, Georgia University Press, Ithaka, New York, 1953, page 56.)
• the emulsion copolymers B are known from DE-C-1 258 728. These copolymers contain 15 to 55 percent by weight of acrylic acid or methacrylic acid, 0 to 10 percent by weight, in particular 2 to 6 percent by weight, acrylamide or methacrylamide and 85 to 45 percent by weight of hydrophobic, water-insoluble homopolymers forming monomers, of which at least 20 percent by weight of esters of acrylic acid or methacrylic acid with aliphatic C. i - to C 4 alcohols. As hydrophobic, water-insoluble homopolymers forming monomers such. B.
• acrylic and methacrylic acid esters of higher aliphatic, cycloaliphatic or aromatic hydroxyl compounds into consideration preferably vinyl acetate, vinyl propionate, acrylic acid methyl ester, acrylic acid ethyl ester and acrylonitrile.
• the copolymers B preferably contain acrylic acid and / or methacrylic acid and exclusively or predominantly acrylic acid and methacrylic acid esters of monohydric alcohols having 1 to 4 carbon atoms.
• terpolymers are preferably used which also contain copolymerized acrylonitrile, vinyl acetate or acrylamide or methacrylamide.
• the copolymers A and B can be prepared by polymerizing the monomers in an aqueous emulsion by processes known per se using the customary anionic or nonionic emulsifiers in the presence of polymerization initiators.
• Suitable emulsifiers are, for example, n-dodecylsulfonic acid potassium or sodium, isooctylbenzenesulfonic acid sodium or potassium salts of the sulfuric acid half-esters of long-chain alcohols with an even carbon number or the corresponding ethoxylated (e.g. with 2 to 25 moles of ethylene oxide) products and with 5 to 25 moles of ethylene oxide p-isooctylphenol and sodium lauryl sulfate.
• the emulsifiers are generally used in amounts of 0.5 to 5 percent by weight, based on the monomers to be polymerized.
• radical-forming compounds such as peroxides, persulfates or azo compounds can be used as polymerization initiators.
• potassium persulfate, cumene hydroperoxide or hydrogen peroxide are suitable.
• activated initiator systems e.g. B. with a system of potassium persulfate and ascorbic acid, oximethanesulfonic acid sodium or triethanolamine.
• the temperatures during the polymerization are in the usual range, e.g. B. between 70 and 95 ° C, they can be lower if redox catalysts are used. It is also possible to polymerize at higher temperatures and under pressure.
• chain transfer agents e.g. B. dodecyl mercaptan and halogenated hydrocarbons such as chloroform, carbon tetrachloride and tetrachlorethylene.
• the binder mixture according to the invention contains 95 to 70 parts by weight of the emulsion copolymer A and 5 to 30 parts by weight of the copolymer B. Outside this range, binder mixtures are obtained whose properties are not so advantageous.
• the paper coating slips contain 3 to 7, preferably 4.5 to 5.5 parts by weight of the binder mixture according to the invention per 100 parts by weight of a finely divided pigment. They can also contain conventional additives, e.g. B. 0.05 to 3 percent by weight of a dispersant based on low molecular weight polymers of acrylic acid (K value of the polymer between 10 and 25) optical brighteners and conventional auxiliaries, such as stearates, shading dyes, foam inhibitors, etc.
• conventional additives e.g. B. 0.05 to 3 percent by weight of a dispersant based on low molecular weight polymers of acrylic acid (K value of the polymer between 10 and 25) optical brighteners and conventional auxiliaries, such as stearates, shading dyes, foam inhibitors, etc.
• aqueous dispersions of copolymers A and B are mixed before the coating color is prepared or during the preparation of the coating color.
• the order in which the individual components are added when preparing the coating color is also irrelevant to the properties of the coating slip or the paper coated with it.
• the mixture of the two copolymers A and B is notable for an exceptionally high storage stability which exceeds that of the known binder mixtures.
• the solids content of the dispersions of copolymers A and B can be varied within a wide range.
• Dispersions with a very high solids content e.g. B. 45 to 50 weight percent.
• the highly concentrated aqueous polymer dispersions are also easy to handle, for example they can be pumped.
• a base such as ammonia, sodium carbonate, an amine or sodium hydroxide solution
• the viscosity increases.
• the finished paper coating slips can be applied to base papers by all known methods. Due to the high shear stability, the paper coating slips can be processed on high-speed roller or doctor coating systems. They are mainly used for the production of such papers that are printed in magazine gravure. This paper gives better print loss than paper made from known paper coating slips. The better quality of the printing loss in gravure printing is determined on the basis of missing dots.
• the binder mixture according to the invention for the production of paper coating slips, based on pigment, less binder is required than is the case with the known binder mixtures. Despite the reduced binder content in the paper coating slips obtained using the binder mixture according to the invention, there is no dusting of the pigment coating on the papers coated with these paper coating slips.
• the parts mentioned in the following examples are parts by weight.
• Feed 1 consists of 460 parts of water, 32 parts of a 28% solution of the sodium salt of a sulfated reaction product from a C 12 / G 14 alcohol which has been reacted with 3 mol of ethylene oxide, 738 parts (82%) of isobutyl acrylate, 126 parts (14 %) Methyl methacrylate, 18 parts (2%) acrylic acid and 18 parts (2%) methacrylamide.
• Feed 2 consists of 200 parts of water and 4.5 parts of potassium peroxydisulfate.
• This copolymer is prepared analogously to copolymer A 1, except that it is composed of 85% isobutyl acrylate, 12% acrylonitrile, 1.5% acrylic acid and 1.5% methacrylamide.
• a copolymer B 1 is prepared which is composed of 75% ethyl acrylate, 5% acrylamide and 20% acrylic acid.
• 100 parts of a commercially available spreading clay are stirred into an aqueous solution of 0.3 part of sodium polyacrylate with a K value of 12 using a high-speed stirrer.
• 9.6 parts of a mixture consisting of 80 parts of a 50% aqueous dispersion of copolymer A 2 and 20 parts of a 45% aqueous dispersion of copolymer B 1 are added as binders, and the coating color is brought to a pH by adding sodium hydroxide solution set from 8.5. With a solids content of 58%, the coating slip has a viscosity of 1400 mPas (measured with a Brookfield viscometer at 100 rpm).
• the paper coating slip thus produced is applied with the aid of a doctor coating system at a speed of 800 m / min to paper which is composed of 55% wood pulp, 45% bleached sulfate pulp, has an ash content of 6% and a weight per unit area of 38 g / m 2 .
• the paper is coated on both sides.
• the coating is 10 g / m 2 and side.
• the paper which is satinised in the super calender at a speed of 300 m / min and 2000 N / cm line printing, has good gloss and smoothness and excellent printability.
• a print that is applied with the help of a Haindl laboratory gravure printing device has, in semitones, less than 10 missing dots on an area of 30 cm 2 . The missing dots were determined by visually counting the missing areas.
• a paper coating slip is produced in accordance with the procedure given in Example 1, but 10.2 parts of a binder mixture of 75 parts of the 50% strength aqueous dispersion of the copolymer are used, based on 100 parts of a commercially available coating clay sates A 1 and 25 parts of the 45% aqueous dispersion of the copolymer B 1.
• the viscosity of the coating color at a solids content of 56% is 1300 mPas (Brookfield viscometer 100 rpm).
• a paper coating slip is prepared as described in Example 1, but 10.2 parts of a mixture of 80 parts of a 50% aqueous dispersion of a copolymer of 55% isobutyl acrylate, 42% styrene, 1 are used as the binder, based on 100 parts of coating clay , 5% acrylic acid and 1.5% methacrylamide and 20 parts of the 45% dispersion of copolymer B 1.
• the coating color has a viscosity of 1200 mPas (Brpokfield viscometer 100 rpm) at a solids content of 56%.
• the paper coated and satined with this paper coating slip in accordance with the specification given in Example 1 has more than 20 missing dots on an area of 30 cm 2 in halftone gravure printing.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Transplanting Machines (AREA)
• Luminescent Compositions (AREA)

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Applications Claiming Priority (2)

Publications (2)

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• 1979
  • 1979-05-17 DE DE19792919937 patent/DE2919937A1/de not_active Withdrawn
• 1980
  • 1980-05-05 EP EP80102414A patent/EP0019170B1/de not_active Expired
  • 1980-05-05 AT AT80102414T patent/ATE2447T1/de not_active IP Right Cessation
  • 1980-05-05 DE DE8080102414T patent/DE3061869D1/de not_active Expired
  • 1980-05-14 FI FI801564A patent/FI71570C/fi not_active IP Right Cessation

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