Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-03-20
2003-10-14
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06632861
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention relates to the use of water-redispersible, protective-colloid-stabilized dispersion powder compositions based on vinylaromatic-1,3-diene copolymers in self-leveling screeds and trowel-applied flooring compositions.
2) Background Art
For many years, dispersion powders have been used, particularly in the construction sector, as a polymeric improver for hydraulically setting systems. An overview of the action of dispersion powders is given in the periodical TIZ (Tonindustrie-Zeitung) 9, p. 698 (1985). Especially the properties of adhesion, wear resistance, scratch resistance and bend resistance of hydraulically setting compositions are improved by adding dispersion powders. Examples of descriptions of these dispersion powders are found in DE-A-2049114 (U.S. Pat. No. 3,784,648), and they are prepared by spray drying aqueous polymer dispersion powders with addition of polyvinyl alcohol and of other additives. The resultant powder, with good free flow and with particle sizes from 10 to 250 &mgr;m, redisperses in water to give a dispersion with particle sizes from 0.1 to 5 &mgr;m. This redispersion should remain stable over a prolonged period, i.e. should not show any tendency toward sedimentation.
An important application sector for dispersion powders is that of hydraulically setting trowel-applied flooring compositions. These trowel-applied flooring compositions have been disclosed in DE-A 3028559 (GB-A 2083015) and EP-A 116524, and are generally composed of cement or mixtures of different cements, carefully balanced filler combinations, dispersion powders, plasticizers and, where appropriate, other additives. DE-A 3028559 proposes modifying the compositions with comminuted elastomers and with dispersion powder based on vinyl acetate-ethylene copolymers. EP-A 116524 recommends the use of polymer powders or polymer dispersions for providing elasticity when producing flowable compositions, the polymer powders recommended being those based on vinyl ester polymers.
DE-B 2064081, DE-B 2102456 (GB-A 1325518), DE-B 2301435 and DE-B 2534564 recommend using polyvinyl acetate dispersion powders as an additive in flowable compositions. The flowable compositions are generally in dry mortar from when they are delivered to the building site, where they are simply mixed with water and spread on the floor. The materials flow out to give a smooth surface which serves directly as the wear layer or serves as substrate for further coatings. This usage always give problems. Particularly when relatively thick layers are applied, uneven areas, such as craters or pinholes, form on the surface. The surface does not become as smooth as the purchaser desires, and requires further work.
The procedure used hitherto to avoid uneven areas of this type has been to use additives. EP-A 477900 (U.S. Pat. No. 5,118,751) recommends the use of fully hydrolyzed copolymers made from 1-alkylvinyl esters and from vinyl esters to eliminate these problems. However, these additives are relatively complicated to prepare and increase the cost of the dispersion powder composition to an unacceptable degree.
It is an object of the present invention, therefore, to eliminate the disadvantages described above for known trowel-applied flooring compositions, in relation to the surface quality of coatings produced from these, without the use of fully hydrolyzed copolymers made from 1-alkylvinyl esters and from vinyl esters, but to do this without losing the advantages gained by adding dispersion powders, for example improved wear resistance, scratch resistance and adhesion.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that the use of powders based on protective-colloid-stabilized vinylaromatic-1,3-diene polymers enables the use of fully hydrolyzed copolymers made from 1-alkylvinyl esters and from vinyl esters to be dispensed with, while retaining equivalent surface qualities and at the same time obtaining good wear resistance, scratch resistance and adhesion.
The invention provides the use of water-redispersible, protective-colloid-stabilized dispersion powder compositions in self-leveling screeds or trowel-applied flooring compositions, wherein the dispersion powder composition comprises
a) a base polymer selected from the group consisting of the vinylaromatic-1,3-diene polymers,
b) from 2 to 25% by weight, based on the base polymer, of one or more protective colloids,
c) from 3 to 30% by weight, based on the total weight of polymeric constituents, of fine antiblocking agent, and
d) from 0.1 to 10% by weight, based on the base polymer, of other additives.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Suitable vinylaromatic compounds are styrene and methylstyrene, copolymerization of styrene being preferred. Examples of 1,3-dienes are 1,3-butadiene and isoprene, 1,3-butadiene being preferred. The copolymers generally contain from 20 to 80% by weight, preferably from 30 to 70% by weight, of vinylaromatic compound, and from 20 to 80% by weight, preferably from 30 to 70% by weight, of 1,3-diene, and other monomers may also be present where appropriate, and the percentage by weight data always give 100% by weight in total.
Up to 30% by weight, based on the total weight of the monomer phase, of other monomers copolymerizable with vinylaromatic compounds and with 1,3-dienes may be copolymerized where appropriate, for example ethylene, vinyl chloride, (meth)acrylates of alcohols having from 1 to 15 carbon atoms, or vinyl esters of unbranched or branched carboxylic acids.
From 0.05 to 10% by weight, based on the total weight of the monomer mixture, of auxiliary monomers may also be copolymerized where appropriate. Examples of auxiliary monomers are ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid or maleic acid; ethylenically unsaturated carboxamides and carbonitriles, preferably acrylamide or acrylonitrile;. mono- and diesters of fumaric acid or maleic acid, such as the diethyl or diisopropyl esters, and also maleic anhydride, ethylenically unsaturated sulfonic acids and salts of these, preferably vinylsulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid. Other examples are precrosslinking comonomers, such as comonomers with two or more ethylenic unsaturations, such as divinyl adipates, diallyl maleate, allyl methacrylate or triallyl cyanurate, or postcrosslinking comonomers, such as acrylamidoglycolic acid (AGA), methyl methylacrylamidoglycolate (MAGME), N-methylol-acrylamide (NMA), N-methylolmethacrylamide, allyl N-methylolcarbamate, alkyl ethers, such as isobutoxy ether, or esters of N-methylolacrylamide, of N-methylolmethacrylamide, or of allyl N-methylol-carbamate. Other suitable comonomers are epoxy-functional comonomers, such as glycidyl methacrylate and glycidyl acrylate. Other examples of comonomers are silicon-functional comonomers, such as acryloxypropyl-tri(alkoxy)- and methacryloxypropyltri(alkoxy)silanes, vinyltrialkoxysilanes and vinylmethyldialkoxysilanes, examples of alkoxy groups which may be present being ethoxy radicals and ethoxy(propylene glycol) ether radicals. Mention may also be made of monomers having hydroxyl or CO groups, for example hydroxyalkyl methacrylates and hydroxyalkyl acrylates, such as hydroxyethyl, hydroxypropyl and hydroxybutyl acrylates and the corresponding methacrylates, and also compounds such as diacetoneacrylamide and acetylacetoxyethyl acrylate and the corresponding methacrylate.
The selection of monomer here, and the selection of the portions by weight of the comonomers, is generally such as to give a glass transition temperature Tg of from −70 to +70° C., preferably from −50 to +50° C., particularly preferably from −20 to +40° C. The glass transition temperature Tg of the polymers may be determined in a known manner by differential scanning calorimetry (DSC). The Tg can also be approximated in advance by using the Fox equation. According to T. G. Fox, Bull. Am. Physics Soc. 1, 3, page 123 (1956): 1/Tg=x
1
/Tg
1
Härzschel Reinhard
Mayer Theo
Weitzel Hans-Peter
Brooks & Kushman P.C.
Szekely Peter
Wacker-Chemie GmbH
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