Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-06-15
2000-10-03
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525207, 525243, C08L 8100, C08L 3500, C08F 2502
Patent
active
061274836
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to pulverulent, redispersible binders which are obtained by spray drying a dispersion comprising a water-soluble polymer, and also to their use in applications in the building industry, specifically for the modification of cement-containing compositions, the formulation of paint compositions and coating compositions.
2) Background Art
Pulverulent binders have a number of advantages compared to the corresponding aqueous formulations: they require a reduced transport and storage capacity and are less sensitive to the action of weathering, frost and microorganisms. To produce such pulverulent binders, spray drying is carried out using spraying auxiliaries which prevent caking or lump formation during the drying process and during subsequent storage and ensure easy redispersion in use.
The spraying auxiliaries known from the prior art have many disadvantages: use of the naphthalenesulfonic acid-formaldehyde or benzene-sulfonic acid-formaldehyde condensation products known from EP-A 78449 and EP-A 407889 gives colored products. The spraying auxiliaries known from DE-A 4118007 and EP-A 467103 impair the product properties of the polymers sprayed therewith when used as binders. EP-A 671435 describes water-soluble protective colloids which comprise olefinically unsaturated sulfonic acids or carboxylic acids, as spraying aids for acrylate dispersions.
It is an object of the invention to provide pulverulent, redispersible binders based on vinyl ester-ethylene copolymers which do not have the disadvantages in use of the known spraying auxiliaries.
SUMMARY OF THE INVENTION
The invention provides dispersion powder compositions which are redispersible in water and comprise vinyl esters of C.sub.2 -C.sub.12 -carboxylic acids, from 1 to 30% by weight of ethylene and from 0 to 20% by weight of vinyl esters of .alpha.-branched monocarboxylic acids having from 5 to 10 carbon atoms, in each case based on the total weight of the vinyl ester-ethylene copolymer, and hydrophobic, essentially water-insoluble monomers, from 20 to 80% by weight of water-soluble, salt-forming monomers selected from the group consisting of ethylenically unsaturated sulfonic acids and from 0 to 50% by weight of ethylenically unsaturated monocarboxylic or dicarboxylic acids or their anhydrides, in each case based on the total weight of the water-soluble copolymer.
Preferred vinyl esters of C.sub.2 -C.sub.12 -carboxylic acids are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate and vinyl pivalate; particular preference is given to vinyl acetate.
Preferred vinyl esters of .alpha.-branched monocarboxylic acids having from 5 to 10 carbon atoms are those having 5, 9 or 10 carbon atoms, for example VV5.RTM., VeoVa9.RTM. or VeoVa10.RTM. (trademarks of the Shell Corporation).
If desired, the vinyl ester-ethylene copolymers can further comprise other monoethylenically unsaturated compounds such as olefins, e.g. propylene, vinylaromatic monomers such as styrene, esters of .alpha.,.beta.-unsaturated monocarboxylic or dicarboxylic acids having from 3 to 6 carbon atoms, e.g. acrylic acid, methacrylic acid, maleic acid or fumaric acid, with alcohols having from 1 to 12 carbon atoms.
If desired, said polymers further comprise from 0.05 to 5% by weight, in each case based on the total weight of the polymer, of one or more auxiliary monomer units to improve the water solubility, for crosslinking or to modify the adhesion properties.
Suitable auxiliary monomers to improve the water solubility are, for example, .alpha.,.beta.-monoethylenically unsaturated monocarboxylic and dicarboxylic acids and their amides or nitriles, e.g. acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide or methacrylamide; ethylenically unsaturated sulfonic acids or their salts, preferably vinylsulfonic acid, 2-acrylamidopropanesulfonate and/or N-vinylpyrrolidone.
Monomer units having a crosslinking action are preferabl
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Hackh's Chemical Dictionary, 4-th Edition, McGraw Hill, p. 711.
English Derwent Abstract Corresponding to EP 0078449 (# 83-46976K).
English Derwent Abstract Corresponding to JP 48007493 (#: 28579 CA).
Ball Peter
Figge Reiner
Weitzel Hans-Peter
Wacker-Chemie GmbH
Wu David W.
Zalukaeva Tanya
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