Polyvinyl-alcohol-stabilized (meth)acrylic acid ester polymers

Abstract

Polyvinyl alcohol-stabilized (meth)acrylic ester polymers, processes for preparing and uses for the same. Where the polyvinyl alcohol-stabilized (meth)acrylic ester polymers have particle sizes Dw of from 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders. Where the (meth)acrylic ester polymers are based on (a) 1% to 30% by weight of one or more vinyl esters of carboxylic acids having 5 to 15 carbon atoms, (b) 20% to 80% by weight of one or more (meth)acrylic esters, wherein the homopolymer of which has a glass transition temperature Tg of ≤20° C., (c) 10% to 70% by weight of one or more (meth)acrylic esters, wherein the homopolymer of which has a glass transition temperature Tg of ≥50° C., and (d) optionally one or more further ethylenically unsaturated monomers. The percentages by weight are based on the total weight of the (meth)acrylic ester polymers.

Claims

1-14. (canceled)

15. Polyvinyl alcohol-stabilized (meth)acrylic ester polymers, comprising: wherein the polyvinyl alcohol-stabilized (meth)acrylic ester polymers have particle sizes Dw of from 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders, wherein the (meth)acrylic ester polymers are based on (a) 1% to 30% by weight of one or more vinyl esters of carboxylic acids having 5 to 15 carbon atoms, (b) 20% to 80% by weight of one or more (meth)acrylic esters, wherein the homopolymer of which has a glass transition temperature Tg of ≤20° C., (c) 10% to 70% by weight of one or more (meth)acrylic esters, wherein the homopolymer of which has a glass transition temperature Tg of ≥50° C., and (d) optionally one or more further ethylenically unsaturated monomers, wherein the percentages by weight are based on the total weight of the (meth)acrylic ester polymers.

16. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the one or more (meth)acrylic esters (b) are selected from the group comprising n-butyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate and stearyl acrylate.

17. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the one or more (meth)acrylic esters (b) are selected from the group comprising methyl methacrylate, tert-butyl methacrylate and tert-butyl acrylate.

18. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers are based to an extent of 50% to 99% by weight on (meth)acrylic esters (b) and (meth)acrylic esters (c), based on the total weight of the (meth)acrylic ester polymers.

19. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers are additionally based on one or more ethylenically unsaturated silanes (d) of the general formula
R.sup.1SiR.sup.2.sub.0-2(OR.sup.3).sub.1-3, wherein R.sup.2 is a C.sub.1 to C.sub.3 alkyl radical; wherein C.sub.1 to C.sub.3 alkoxy radical or halogen; wherein R.sup.1 denotes CH.sub.2═CR.sup.4—(CH.sub.2).sub.0-1 or CH.sub.2═CR.sup.4CO.sub.2(CH.sub.2).sub.1-3 with R.sup.4 as a carbon radical having 1 to 10 carbon atoms; wherein R.sup.3 is an unbranched or branched; and optionally substituted alkyl radical having 1 to 12 carbon atoms.

20. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers are additionally based on glycidyl methacrylate or glycidyl acrylate.

21. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers are based to an extent of 0 to 20% by weight, based on the total weight of the (meth)acrylic ester polymers, on one or more ethylenically unsaturated monomers (f) selected from the group comprising vinyl esters of carboxylic acids having 2 to 4 carbon atoms, olefins, dienes, vinylaromatics and vinyl halides.

22. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers contain no ethylene units and/or no units of a vinyl ester of a carboxylic acid having 2 to 4 carbon atoms.

23. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the polyvinyl alcohols are composed exclusively of vinyl alcohol and vinyl acetate units.

24. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein no emulsifiers are present.

25. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the (meth)acrylic ester polymers have a polydispersity PD of ≤3.

26. The polyvinyl alcohol-stabilized (meth)acrylic ester polymers of claim 15, wherein the polyvinyl alcohol-stabilized (meth)acrylic ester polymers are used in leveling compounds, renders, spackling compounds, jointing mortars, tile adhesives, integrated thermal insulation adhesives, sealing slurries, thermal insulation composite systems or paints.

27. A process for preparing polyvinyl alcohol-stabilized (meth)acrylic ester polymers, comprising: providing polyvinyl alcohol-stabilized (meth)acrylic ester polymers having a particle sizes Dw of from 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders by free-radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of polyvinyl alcohol in aqueous medium and optionally subsequent drying, wherein (a) 1% to 30% by weight of one or more vinyl esters of carboxylic acids having 5 to 15 carbon atoms, (b) 20% to 80% by weight of one or more (meth)acrylic esters, the homopolymer of which has a glass transition temperature Tg of ≤20° C., (c) 10% to 70% by weight of one or more (meth)acrylic esters, the homopolymer of which has a glass transition temperature Tg of ≥50° C., and (d) optionally one or more further ethylenically unsaturated monomers are polymerized, and where the percentages by weight are based on the total weight of the (meth)acrylic ester polymers.

28. The process of claim 27, wherein the vinyl esters (a) are initially charged in part or in full and the (meth)acrylic esters (b) and/or the (meth)acrylic esters (c) and optionally the further ethylenically unsaturated monomers (d) are metered in in full or in part.

Description

PREPARATION OF THE POLYMER DISPERSIONS

EXAMPLE 1 (EX. 1)

[0075] A polymerization reactor with a volume of 3 liters was initially charged with the following components:

[0076] 330 g of water, 132 g of a 20% aqueous solution of a partially hydrolyzed polyvinyl alcohol (degree of hydrolysis: 88 mol %; Hoppler viscosity of 4 mPas (determined according to Hoppler in accordance with DIN 53015, 20° C., 4% aqueous solution)) and 0.6 g of a 1% aqueous iron ammonium sulfate solution.

[0077] The reactor was provided with a nitrogen protective gas atmosphere. 197 g of vinyl laurate were added and the mixture was heated to 70° C.

[0078] The polymerization was initiated by adding 5% by weight aqueous tert-butyl hydroperoxide solution (TBHP) at a rate of 12 g/h and adding 5% by weight aqueous ascorbic acid solution at a rate of 12 g/h.

[0079] After 10 min, the metered monomer addition was started, consisting of 592 g of butyl acrylate and 527 g of methyl methacrylate at a rate of 280 g/h (duration 4 h). At the same time, an aqueous metered addition was started, consisting of 557 g of water and 559 g of a 20% by weight solution of a partially hydrolyzed polyvinyl alcohol (degree of hydrolysis: 88 mol %; Hoppler viscosity: 4 mPas) at a rate of 280 g/h (duration 4 h). The polymerization was continued for a further 1 h after the metered monomer addition had ended.

[0080] After the dispersion had cooled, postpolymerization was effected on addition of 6.5 g of a 5% by weight aqueous TBHP solution and 6.5 g of a 5% by weight aqueous ascorbic acid solution. The properties of the polymer dispersion obtained in this way are summarized in table 1. The properties were determined as indicated further above in the general description.

EXAMPLES 2 TO 6 AND COMPARATIVE EXAMPLE 7 (EX. 2-6, CEX. 7)

[0081] The polymer dispersions of Ex. 2-6 and CEx. 7 were prepared as described for example 1 with the difference that the monomers indicated in table 2 were used.

[0082] The properties of the polymer dispersions obtained in this way are summarized in table 1. The properties were determined as indicated further above in the general description or can be determined in a conventional manner.

TABLE-US-00001 TABLE 1 Properties of the polymer dispersions of examples 1 to 6 and comparative example 7: Solids Brookfield Particle size distribution content viscosity* Dw Dn Tg [%] pH [mPas] [nm] [nm] Dw/Dn [° C.] Ex. 1 46.2 3.9 696 393 225 1.75 −5.0 Ex. 2 43.2 4 118 780 393 1.98 −3.4 Ex. 3 44.2 3.9 335 390 205 1.90 −4.5 Ex. 4 46.7 4.1 1320 297 205 1.45 −5.6 Ex. 5 46.9 4.3 410 431 271 1.59 −9.9 Ex. 6 46.2 4 212 770 358 2.15 −23.5 CEx. 7 47.7 4.1 2245 1748 290 6.03 0 *Brookfield viscosity: determined at 20 revolutions and 23° C.

TABLE-US-00002 TABLE 2 Monomer composition of the polymers of examples 1 to 6 and comparative example 7: Vinyl Butyl Methyl meth- Vinyltri- Glycidyl meth- laurate acrylate acrylate ethoxysilane acrylate [parts by wt.] [parts by wt.] [parts by wt.] [parts by wt.] [parts by wt.] Ex. 1 15 45 40 Ex. 2 10 50 40 Ex. 3 15 45 40 0.8 0.8 Ex. 4 15 45 40 0.8 1.6 Ex. 5 15 50 35 Ex. 6 15 60 25 CEx. 7 55 45

[0083] Preparation of the Dispersion Powder Compositions P1 to P6 and CP7:

[0084] The polymer dispersions from the (comparative) examples 1 to 7 were each dried, with addition of 2.0% weight, based on the polymer content of the dispersion (solid/solid), of a partially hydrolyzed polyvinyl alcohol (degree of hydrolysis: 88 mol %; Hoppler viscosity: 4 mPas in 4% aqueous solution)) and 6.0% by weight, based on the polymer content of the dispersion (solid/solid), of a partially hydrolyzed polyvinyl alcohol (degree of hydrolysis: 88 mol %; Hoppler viscosity: 13 mPas in 4% aqueous solution)), by spray drying in a manner conventional per se, at an entry temperature of 130° C. and an exit temperature of 80° C., to obtain redispersible powders. The powders were stabilized by addition of 4% by weight of kaolin and 16% by weight of calcium carbonate as anticaking agent.

[0085] In all of (comparative) examples 1 to 7, free-flowing, stable dispersion powders were obtained.

[0086] Determination of the Properties of the Dispersion Powder Compositions P1 to P6 and CP7:

[0087] Determination of the Blocking Resistance (BR):

[0088] For determining the blocking resistance, the powder under test was filled into an iron tube with a screw thread and was then loaded with a metal ram. It was stored under loading in a drying cabinet at 50° C. for 16 hours. After cooling to room temperature, the powder was removed from the tube and the blocking stability was determined qualitatively by crushing the powder. The results of the testing are listed in table 3.

[0089] The blocking stability was classified as follows:

1=very good blocking stability
2=good blocking stability
3=satisfactory blocking stability
4=not blocking-stable, powder no longer free-flowing after crushing.

[0090] Determination of the Sedimentation Behavior (TS):

[0091] The sedimentation behavior of redispersions serves as a measure of the redispersibility of redispersible powders. The powder under test was redispersed at a concentration of 50% by weight in water through application of strong shear forces.

[0092] The sedimentation behavior was then determined on diluted redispersions (0.5% solids content), and to this end 100 ml of this dispersion was filled into a graduated tube and the height of the sedimented solid was measured. The values are reported in mm of sedimentation after 1 hour and after 24 hours. Values of greater than 7 indicate a highly unsatisfactory redispersion of the powder. The results of the testing are listed in table 3.

TABLE-US-00003 TABLE 3 Dispersion powder compositions of examples 1 to 6 and comparative example 7: Powder properties Dispersion Powder TS (1 h) TS (24 h) BR Ex. 1 D1 P1 0.3 0.6 2 Ex. 2 D2 P2 0.2 0.6 2-3 Ex. 3 D3 P3 2.8 4.2 2-3 Ex. 4 D4 P4 3.3 5.1 2-3 Ex. 5 D5 P5 0.2 0.6 2-3 Ex. 6 D6 P6 0.3 0.8 2-3 CEx. 7 CD7 CP7 3.9 7.8 5

[0093] Performance Testing of the Dispersion Powder Compositions:

[0094] Tile Adhesive:

[0095] The dispersion powder compositions were tested for their suitability for the adhesive bonding of ceramic tiles. Dry mortars of the following composition were prepared:

420 parts Milke Premium CEM I 52.5 R cement,
446 parts quartz sand,
80 parts calcium carbonate,
4 parts Tylose MB60000 (thickener),
10 parts calcium formate (accelerator),
40 parts dispersion powder composition as indicated in table 4.

[0096] The tile adhesive mortar was mixed with 34 g of water per 100 g of dry mortar.

[0097] The tiles were laid with the tile adhesive in the conventional manner.

[0098] Testing in accordance with DIN EN 12 004 (test standard EN 1348) gave the test results listed in table 4.

TABLE-US-00004 TABLE 4 Test results of the tile adhesive: Tensile bond strength test [N/mm.sup.2] Powder Standard climate Water Heat FT Open time 30′ P1 1.28 0.97 1.12 1.25 0.81 P2 1.31 1.02 1.19 1.28 0.85 P3 1.33 1.12 1.34 1.26 0.76 P4 1.35 1.21 1.32 1.38 0.69 P5 1.29 1.14 1.27 1.31 0.78 P6 1.19 1.01 1.21 1.23 0.84 CP7 1.18 0.87 1.08 1.19 0.42

[0099] Compared to the tile adhesive with the comparative dispersion powder composition CP7, the tile adhesives with the dispersion powder compositions P1 to P6 of the invention exhibited improved tensile bond strengths, in particular improved wet strengths, freeze-thaw resistance (FT) and even after thermal stress.

[0100] Sealing Slurry:

[0101] The dispersion powder compositions P3 and P4 and also CP7 were also tested for tensile bond strength in flexible sealing slurries.

[0102] The sealing slurries were based on the formulation of table 5 and were prepared and applied in the conventional manner.

[0103] The testing of the tensile bond strength of the sealing slurries after storage in a standard climate and after storage in water was carried out in accordance with EN 14891. The test results are given in table 6.

TABLE-US-00005 TABLE 5 Formulation of the sealing slurry: Milke Premium CEM I 52.5 R 24.00 g Ternal RG 24.00 g F36 quartz sand 54.00 g BCS 413 quartz sand 30.00 g Poraver (0.1-0.3 mm) 6.00 g Acrylate thickener 0.40 g Retarder (polyphosphate) 0.70 g Lithium carbonate (accelerator) 0.06 g P801 0.84 g Polymer powder 60.00 g Total 200.00 g Water 54 g

TABLE-US-00006 TABLE 6 Tensile bond strengths of the sealing slurry: Powder Standard climate Water P3 3.17 1.08 P4 3.06 1.03 CP7 1.98 0.78

[0104] The tensile bond strength of the sealing slurries can be improved by the use of the dispersion powder compositions of the invention.

[0105] Emulsion Paints:

[0106] The dispersion powder compositions were tested for their suitability for use in emulsion paints. The emulsion paints were based on the formulation of table 7 and were prepared in the conventional manner and tested as described below. The test results are summarized in table 8.

TABLE-US-00007 TABLE 7 Formulation of the emulsion paints: Formulation constituent Mass [g] Dispersion powder 187.9 TiO.sub.2 pigment (Kronos 2190) 62.6 Thickener (Tylose MH 30.000 yp2) 0.9 Plasticizer (1,6-hexanediol) 9.4 CaCO.sub.3 filler (Omyacarb 5 GU) 197.9 CaCO.sub.3 filler (Omyacarb 2 GU) 171.6 Portland cement (Dyckerhoff white) 4.1 Lime (Wallhalla premium lime hydrate) 1.8 Cellulose fiber (Arbocel BE 600-30 PU) 47.4 Dispersing agent (Calgon N) 3.1 Sum total of solid components 686.7 Water 313.3 Total 1000.0

[0107] Test Methods:

[0108] Testing of the Scrub Resistance SR (Wet Abrasion Resistance) of the Emulsion Paints:

[0109] To determine the wet abrasion resistance, the emulsion paints prepared from the powder paints were each tested using the nonwoven pad method in accordance with ISO 11998.

[0110] The emulsion paint was in each case applied to a Leneta film (PVC film) using an applicator at a layer thickness of 300 μm (wet).

[0111] This was followed by storage for 72 hours in a standard climate (DIN 50014, 23° C. and 50% relative air humidity), then for 24 hours at 50° C. and finally for 24 hours in a standard climate. A dry layer thickness of ca. 200 μm resulted.

[0112] Then three test strips each measuring 2.5 cm×7.5 cm were cut out and then weighed.

[0113] The scrub test was carried out for 200 cycles and then weighing was performed again. The paint erosion in μm was then calculated from the color density of the scrubbed area and the loss of mass of the paint film.

[0114] An average of three measurements was determined in each case.

[0115] The scrub resistance after 200 cycles is rated in classes:

Class 1 with abrasion of less than 5 μm,
Class 2 with abrasion of between 5 μm and less than 20 μm,
Class 3 with abrasion of between 20 μm and less than 70 μm.

[0116] Measurement of the BF100 Brookfield Viscosities of the Emulsion Paints:

[0117] The Brookfield viscosity of the emulsion paints prepared with the powder paint compositions was measured in each case with a Brookfield viscometer BF 35, after heating to 23° C., using the spindle specified in the operating instructions, at 100 revolutions per minute (BF100). The viscosity is stated in mPas in each case.

[0118] Determination of the Opacity of the Emulsion Paints:

[0119] The opacity was determined using the method in accordance with DIN EN 13300 described in the “Guideline for determining the covering capacity” of the Association of the German Paint Industry, July 2002 edition.

[0120] The emulsion paints were applied using an automatic film applicator with a knife coater having a gap height of 150 μm and 225 μm, each on black-and-white contrast cards (type 3H from Lenetta) with a tristimulus value Y over black of 7 or less and a tristimulus value Y over white of 80 to 90.

[0121] The contrast cards coated in this way were dried for 24 hours at 23° C. and 50% relative air humidity and then weighed.

[0122] The coverage in m.sup.2/l was calculated from the application amount in g/m.sup.2 and the color density. The tristimulus values Y (color standards) were measured over the black and the white base using a colorimeter (Elrepho 450X from Datacolor) and the “contrast ratio” in “%” was calculated.

[0123] The values for the contrast ratio determined in this way were plotted on a graph against the corresponding yield (m.sup.2/l). By interpolation, the coverage C was determined at 7 m.sup.2/l at a contrast ratio of 98%.

[0124] The higher the coverage C, the better the opacity.

TABLE-US-00008 TABLE 8 Test results of the emulsion paints: BF100 Wet abrasion viscosity resistance Powder [mPas] pH Color density [μm] Opacity P1 6820 8.3 1.195 24.7 95.3 P2 6350 8.6 1.275 30.3 96 P3 7170 8.4 1.222 21.3 96.1 P4 7840 8.4 1.21 33.7 96.9 P5 6060 8.3 1.168 34.5 95.8 P6 5710 8.3 1.106 35.1 96 CP7 5890 8.5 1.241 39.9 96.1

[0125] The wet abrasion resistance of emulsion paints could be considerably raised with the powders of the invention. The other properties satisfy the requirements on emulsion paints.