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
  • D21H19/60—Polyalkenylalcohols; Polyalkenylethers; Polyalkenylesters

Definitions

• coating slips are known to be used which essentially consist of a pigment suspended in water with the aid of a dispersing agent, e.g. Kaolin, satin white or calcium carbonate and binders exist.
• a dispersing agent e.g. Kaolin, satin white or calcium carbonate and binders exist.
• Cobinder controls accordinging to G. Hirsch, Das Paper 32 (10A), 1978, 66-72 above all the viscosity and water retention of coating colors, improve individual coating properties such as pick resistance or ink absorption and above all have an excellent effect for optical brighteners.
• semi-synthetic, water-soluble polymers such as the sodium salt of carboxymethyl cellulose and fully synthetic polymers such as copolymers of vinyl acetate and acrylamide (DE-A-2450039) and copolymers of unsaturated acid amides with vinyl or allyl alcohol (DE-A-2933765 & CA 1163395).
• Polymers containing acrylic esters are also used as cobinders, which are added to the coating color as acidic aqueous dispersions and only develop their effect when the alkali is set (see G. Hirsch, Das Textil 32 (10 A1), 1978, 66-72).
• Copolymers containing vinyl alcohol and acrylamide units are known from DE-A-1913667. It is proposed to use these copolymers as binders for paper coating slips, since these copolymers improve the flowability and water resistance of the coating slips compared to fully hydrolyzed polyvinyl alcohols. A disadvantage of these copolymers is their poor carrier properties for optical brighteners.
• polyvinyl alcohols are not only excellent binders for pigments, they also outperform all of the above-mentioned cobinder systems in terms of their carrier properties for optical brighteners (see H.G. Oesterlin, Das Textil 36, 1982, 66-72, 121-126, 170-175). According to their degree of hydrolysis, a distinction is made between polyvinyl alcohols (PVAL) so-called fully saponified types (degree of hydrolysis 98-100 mol%) and partially saponified types with degrees of hydrolysis of 70-90 mol%. In the paper coating shop, after extensive investigations (H. G.
• coated flat structures e.g. of print media, especially coated paper, cardboard and / or cardboard, to find ways to avoid the difficulties and disadvantages described above, without jeopardizing the advantages of the previous masses.
• the polymers preferably consist of 60-95% by weight, in particular 70-95% by weight of units a, 5-40% by weight, in particular 5-20% by weight of units b, and each 0-10% by weight, in particular each 0-5 wt% units c and d.
• the amount of comonomer units b-e is in the range 5 to 20% by weight, in particular 7.5-10% by weight, the amount of vinyl acylate units being particularly preferably as small as possible, i.e. at e.g. 0-2% by weight.
• the amount of units e is also preferably 0-1% by weight, in particular still in the lower half of this range, e.g. even below 0.2% by weight.
• the polymers mentioned according to the invention are not only distinguished by the better miscibility of their solutions with the pigment slurry, the pigment shock being significantly reduced, if it still occurs, compared to the addition of solutions of polyvinyl alcohols comparable in viscosity and degree of hydrolysis, but Surprisingly also in that they can be stirred directly into pigment suspensions in bulk without prior dissolution or dilution.
• the polymers used according to the invention have a stronger pigment-binding capacity and higher water retention values than comparable technically used fully saponified polyvinyl alcohols, which expands their field of use as cobinder.
• the methyl radical is preferred as the alkyl group in units b; however, branched and unbranched C 2 to C 4 alkyl groups can also be used.
• the polymers which have hitherto been used as protective colloids for radical polymerization (DE-C-1026074, cf. Chem. Abstr. 54, 16024 h) or as base material for the production of moldings (Chem. Abstr. 87, 118 700c) or in a mixture with glycerol as a water-soluble hot melt adhesive (Chem. Abstr.
• 91, 176392 x can be prepared in a two-stage process, in the first stage by copolymerization of vinyl acylate, in particular vinyl acetate and / or vinyl propionate, with 1-alkyl vinyl acylate, in particular isopropenyl acetate and / or -propionate, and optionally allyl acylate, in particular allyl acetate and / or -propionate in a conventional manner by radical suspension or emulsion polymerization in water or by radical polymerization in bulk or in a suitable organic solvent such as, for example Alcohols or esters. Examples include: methanol, ethanol, isopropanol, methyl, ethyl, isopropyl and butyl acetate.
• the copolymer obtained in this way is prepared in accordance with the processes known in the preparation of polyvinyl alcohols or (partially) saponified polyvinyl esters in alkaline or acidic form with the addition of solvolysis or hydrolysis catalyst or stoichiometric amounts of corresponding reactants, e.g. of metal hydroxides, preferably as completely solvolysed or hydrolyzed, e.g. by transesterification of the acylate residues of the polymers.
• reactants e.g. of metal hydroxides
• the molecular weights can be adjusted in the customary manner by varying the initiator concentrations, temperature and addition of polymerization regulators such as, for example, bromotrichloromethane and thioacetic acid during the polymerization. Higher molecular weights can also be set by adding small amounts of polyethylenically unsaturated compounds such as divinyl adipate and allyl methacrylate.
• the compounds according to the invention with their use as cobinder preferably have Höppler viscosities of 3-20, in particular 4 to 12 mPas (measured as a 4% strength aqueous solution).
• a further possibility of varying the polymers used according to the invention is the incorporation (copolymerization) of units which are derived from vinyl esters of increased hydrophobicity, that is to say, for example, from the vinyl fatty acid esters, for example vinyl stearate and / or vinyl laurate and / or from Versatic acid vinyl esters (VeoVa 0 , esters of branched carboxylic acids with mostly 10 to 20 C atoms produced by the so-called Koch synthesis, Shell AG). These units increase, for example, the surface-active effect of the polymers.
• ethylene for example, can also be polymerized in amounts of 0-5, in particular 0-1% by weight, of ethylene units.
• coating slips for flat substrates in particular for coated printing substrates, which include paper, cardboard and cardboard in particular, are known in principle. Reference is only made, for example, to DE-A-2933765 and DE-A-2450039.
• the polymer used according to the invention can be used as a cobinder in known coating compositions in customary amounts and can at least partially, preferably entirely, replace the cobinder used there, e.g. the polymer B of DE-A-2933765 or the copolymer of the acrylamide of DE-A-2450039.
• the results are shown in Table 2.
• the first value represents the result at 10 rpm
• the second value represents the result at 100 rpm.
• the conventional polyvinyl alcohols practically only act as another filler.
• a paper coating slip with the following composition (FG 61%) was produced and the water retention capacity was measured using the Venema method 6 ).
• the coating colors were spread on one side on a test coating system by means of a scraper applicator at a speed of 100 m / min onto a wood-containing base paper with a basis weight of approx. 35 g / m 2 .
• the application weight was 10.3 g / m 2 .
• the coated papers were then satinized on a 2-roll laboratory calendar and the degree of whiteness using a

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Paints Or Removers (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Amplifiers (AREA)
• Developing Agents For Electrophotography (AREA)
• Oscillators With Electromechanical Resonators (AREA)
• Indole Compounds (AREA)
• Separation Of Suspended Particles By Flocculating Agents (AREA)

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Publications (2)

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• 1986
  • 1986-07-08 DE DE19863622820 patent/DE3622820A1/de not_active Withdrawn
• 1987
  • 1987-06-05 CA CA000538966A patent/CA1296827C/en not_active Expired - Lifetime
  • 1987-06-24 FI FI872795A patent/FI85739C/fi not_active IP Right Cessation
  • 1987-06-26 JP JP62157991A patent/JPH0676573B2/ja not_active Expired - Lifetime
  • 1987-07-08 EP EP87109835A patent/EP0253285B1/de not_active Expired - Lifetime
  • 1987-07-08 AT AT87109835T patent/ATE56767T1/de not_active IP Right Cessation
  • 1987-07-08 DE DE8787109835T patent/DE3765040D1/de not_active Expired - Lifetime
  • 1987-07-08 ES ES87109835T patent/ES2018212B3/es not_active Expired - Lifetime
• 1988
  • 1988-11-17 US US07/272,634 patent/US4879336A/en not_active Expired - Lifetime

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