AQUEOUS POLYMER LATEX

Abstract

The present invention relates to aqueous polymer latexes of film-forming copolymers obtainable by aqueous emulsion polymerisation of monomers M, which comprise at least 80% by weight, based on the monomers M, of—at least one non-ionic monomer M1, which is selected from C.sub.1-C.sub.20-alkyl esters of acrylic acid, C.sub.5-C.sub.20-cycloalkyl esters of acrylic acid, C.sub.1-C.sub.20-alkyl esters of methacrylic acid, C.sub.5-C.sub.20-cycloalkyl esters of methacrylic acid and monovinyl aromatic monomers; —one or more monoethylenically unsaturated monomers M2, which are selected from monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms and monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms; and where the polymer latex contains an emulsifier combination comprising i. at least one first emulsifier (1), which is selected from salts, in particular from the alkali metal salts and the ammonium salts of sulfated ethoxylated C.sub.8-C.sub.20-alkanols having a degree of ethoxylation in the range from 5 to 20 and sulfated ethoxylated tristyrylphenols having a degree of ethoxylation in the range from 5 to 20, and ii. at least one second emulsifier (2), which is selected from the salts, in particular from the alkali metal salts and the ammonium salts of a sulfated ethoxylated C.sub.8-C.sub.20-alkanol having a degree of ethoxylation in the range from 21 to 50 and sulfated ethoxylated tristyrylphenols having a degree of ethoxylation in the range from 21 to 50. The present invention also relates to a process for producing such polymer latexes and to the use of these polymer latexes as binders in waterborne coating compositions which contain at least one inorganic tannin blocking compound and to the use of such coating compositions for coating tannin-containing substrates such as wood or woodbased materials.

Claims

1.-23. (canceled)

24. An aqueous polymer latex of a film-forming copolymer obtainable by aqueous emulsion polymerisation of monomers M, which comprise at least 80% by weight, based on the monomers M, of at least one non-ionic monomer M1, which is selected from C.sub.1-C.sub.20-alkyl esters of acrylic acid, C.sub.5-C.sub.20-cycloalkyl esters of acrylic acid, C.sub.1-C.sub.20-alkyl esters of methacrylic acid, C.sub.5-C.sub.20-cycloalkyl esters of methacrylic acid, and monovinyl aromatic monomers; one or more monoethylenically unsaturated monomers M2, which are selected from monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms and monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms; where the polymer latex contains an emulsifier combination comprising i. at least one first emulsifier (1), which is selected from salts of sulfated ethoxylated C.sub.8-C.sub.20-alkanols having a degree of ethoxylation in the range from 5 to 20 and sulfated ethoxylated tristyrylphenols having a degree of ethoxylation in the range from 5 to 20; ii. at least one second emulsifier (2), which is selected from salts of a sulfated ethoxylated C.sub.8-C.sub.20-alkanol having a degree of ethoxylation in the range from 21 to 50 and sulfated ethoxylated tristyrylphenols having a degree of ethoxylation in the range from 21 to 50.

25. The aqueous polymer latex of claim 24, wherein the first emulsifier (1) is selected from the alkali metal salts and ammonium salts of sulfated ethoxylated C.sub.8-C.sub.20-alkanols having a degree of ethoxylation in the range from 5 to 20.

26. The aqueous polymer latex of claim 24, wherein the second emulsifier (2) is selected from the alkali metal salts and ammonium salts of sulfated ethoxylated C.sub.8-C.sub.20-alkanols having a degree of ethoxylation in the range from 21 to 50.

27. The aqueous polymer latex of claim 24, wherein the weight ratio of the first emulsifier (1) to the second emulsifier (2) is in the range from 15:85 to 70:30.

28. The aqueous polymer latex of claim 24, wherein the total amount of emulsifiers present in the aqueous polymer latex is in the range from 0.1 to 5% by weight based on the film-forming copolymer.

29. The aqueous polymer latex of claim 24, wherein the first emulsifier and the second emulsifier amount to at least 90% by weight of the total amount of emulsifiers contained in the polymer latex.

30. The aqueous polymer latex of claim 24, wherein the particles of the copolymer contained in the polymer latex have a Z-average particle diameter in the range from 40 to 500 nm, as determined by quasi-elastic light scattering.

31. The aqueous polymer latex of claim 24, where the monomers M1 are a mixture of at least one monomer M1a, selected from C.sub.1-C.sub.20-alkyl esters of acrylic acid and C.sub.5-C.sub.20-alkyl esters of methacrylic acid; and at least one monomer M1b, selected from monovinyl aromatic monomers, and C.sub.1-C.sub.4-alkyl esters of methacrylic acid and mixtures thereof.

32. The aqueous polymer latex of claim 24, where the monomers M2 are selected from acrylic acid, methacrylic acid and mixtures thereof.

33. The aqueous polymer latex of claim 24, where the monomers M further comprise at least one monomer M3, which is selected from the group consisting of non-ionic monoethylenically unsaturated monomers which have a functional group selected from the group consisting of hydroxyalkyl groups, a primary carboxamide group, urea groups and keto groups.

34. The aqueous polymer latex of claim 24, where the monomers M consist of: 85 to 99.95% by weight, based on the total weight of the monomers contained in the monomer composition M, of ethylenically unsaturated monomers M1; 0.05 to 5% by weight, based on the total weight of the monomers contained in the monomer composition M, of one or more monoethylenically unsaturated monomers M2; 0 to 14.95% by weight, based on the total weight of the monomers contained in the monomer composition M, of one or more non-ionic monomers M3.

35. The aqueous polymer latex of claim 24, which comprises a first phase of a copolymer, which has a glass transition temperature Tg(1) in the range from −25 to +60° C. and a second phase of a copolymer, which has a glass transition temperature Tg(2) in the range from +50 to +150° C., provided that the absolute value of |Tg(2)−Tg(1)| is at least 10° C.

36. The aqueous polymer latex of claim 24, which is obtainable by aqueous emulsion polymerisation of the monomers M in the presence of the emulsifier combination.

37. A process for producing an aqueous polymer latex of claim 24, which comprises performing an aqueous emulsion polymerisation of the monomers M in the presence of the emulsifier combination.

38. The process of claim 37, where the aqueous emulsion polymerization is performed by a monomer feed process, where at least 90% of the monomers M to be polymerized are fed to a polymerisation vessel as an aqueous emulsion of the monomers, which contains at least a portion of the second emulsifier.

39. The process of claim 38, where the reaction vessel contains at least a portion of the first emulsifier, before the feeding of the aqueous emulsion of the monomers is started.

40. The process of claim 37, where the aqueous emulsion polymerization is a multistage aqueous emulsion polymerization, which comprises: i. a first stage of aqueous emulsion polymerizing a monomer composition M.sup.i, which corresponds to a theoretical glass transition temperature Tg.sup.t(i) according to Fox in the range from −25 to +60° C. to obtain a first stage polymer latex, and a ii. a second stage of aqueous emulsion polymerizing a monomer composition M.sup.ii, in the first stage polymer latex, where the monomer composition M.sup.ii corresponds to a theoretical glass transition temperature Tg.sup.t(ii) according to Fox in the range from 50 to 150° C., provided that the temperature difference Tg.sup.t(ii)−Tg.sup.t(i) is at least +10° C.

41. The process of claim 37, where the aqueous emulsion polymerization is a multistage aqueous emulsion polymerization, which comprises: i. a first stage of aqueous emulsion polymerizing a monomer composition M.sup.i, which corresponds to a theoretical glass transition temperature Tg.sup.t(i) according to Fox in the range from 50 to 150° C. to obtain a first stage polymer latex, and a ii. a second stage of aqueous emulsion polymerizing a monomer composition M.sup.ii, in the first stage polymer latex, where the monomer composition M.sup.ii corresponds to a theoretical glass transition temperature Tg.sup.t(ii) according to Fox in the range from −25 to +60° C., provided that the temperature difference Tg.sup.t(i)−Tg.sup.t(ii) is at least +10° C.

42. A waterborne coating composition which contains a) a binder polymer in the form of the aqueous polymer latex as defined in claim 24; and b) at least one inorganic tannin blocking compound.

43. The coating composition of claim 42, where the inorganic tannin blocking compound is selected from the group consisting of oxides, phosphates and phosphosilicates of polyvalent metals, which are selected from zinc, aluminium, zirconium, barium and strontium.

44. The coating composition of claim 42, where the inorganic tannin blocking compound comprises zinc oxide.

45. The coating composition of claim 42, which further comprises a titanium dioxide pigment.

46. The use of the coating compositions of claim 42 for coating a tannin containing substrate.

Description

4. PREPARATION OF POLYMER LATEXES

4.1 EXAMPLE 1

[0271] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

[0272] 357.5 g Deionized water and [0273] 64.2 g Emulsifier 1

[0274] were added in a nitrogen atmosphere and heated to 87° C. whilst being stirred. At 80° C., 43.4 g of feed 2 and 3.2 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added and further heated to 87° C. 5 minutes later, feed 1 and 2 (remaining quantity) were started and metered into the reaction vessel within 120 minutes. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then, feed 3 and 4 were metered into the reaction vessel in 45 minutes.

[0275] Feed 1: [0276] 13.7 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0277] Feed 2 (Emulsion Comprising):

TABLE-US-00001 537.9 g Deionized water 47.1 g Emulsifier 2 8.0 g Acrylic acid 9.0 g 50% b.w. aqueous solution of acrylamide 313.0 g Methyl methacrylate 448.7 g 2-Ethylhexyl acrylate 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0278] Feed 3:

TABLE-US-00002 5.1 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 4 (emulsion comprising): 277.0 g Deionized water 17.9 g Emulsifier 2 8.0 g Acrylic acid 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 232.9 g Methyl methacrylate

[0279] After completion of feed 3 and 4, the polymerization mixture was allowed to react at 87° C. for 30 minutes; then 5.3 g of a 25% b.w. aqueous solution of ammonia and 55.4 g of deionized water were added. While being stirred for 60 minutes, the mixture was cooled down to 82° C. In parallel, 22.9 g of a 7.7% b.w. aqueous solution of hydrogen peroxide and 22.8 g of a 6.8% b.w. aqueous solution of L-ascorbic acid were metered into the reaction vessel. After that, 15.4 g of a 7.1% b.w. aqueous ammonia solution were added; the mixture was cooled down to 22° C., and the aqueous polymer dispersion was filtered off via a 125 μm filter.

[0280] The obtained polymer latex had a solids content of 44.8%, a pH-value of 7.7, and an average particle size of 76 nm according to HDC.

4.2 EXAMPLE 2

[0281] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00003 390.0 g Deionized water and 70.0 g Emulsifier 1

[0282] were added in a nitrogen atmosphere and heated to 80° C. whilst being stirred. At 80° C., 30.0 g methyl methacrylate and 3.5 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added. 5 minutes later, feed 1 and 2 were started and metered into the reaction vessel within 109 minutes; the polymerization temperature was set to 87° C. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then feed 3 and 4 were metered into the reaction vessel in 52 minutes.

[0283] Feed 1: [0284] 14.1 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0285] Feed 2 (Emulsion Comprising):

TABLE-US-00004 586.8 g Deionized water 46.5 g Emulsifier 2 11.2 g Acrylic acid 9.1 g 50% b.w. aqueous solution of acrylamide 307.0 g Methyl methacrylate 445.1 g 2-Ethylhexyl acrylate 42.2 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0286] Feed 3:

TABLE-US-00005 6.5 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 4 (emulsion comprising): 302.2 g Deionized water 22.9 g Emulsifier 2 20.2 g Acrylic acid 54.0 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 285.8 g Methyl methacrylate

[0287] After completion of feed 3 and 4, the polymerization mixture was allowed to react at 87° C. for 30 minutes; then 4.8 g of a 25% b.w. aqueous solution of ammonia and 60.5 g of deionized water were added; the mixture was stirred for another 60 minutes. In the meantime, 17.0 g of an 11.3% b.w. aqueous solution of hydrogen peroxide and 16.7 g of a 10.1% b.w. aqueous solution of L-Ascorbic acid were metered into the reaction vessel. After that, 12 g of a 25% b.w. aqueous solution of ammonia and 26.6 g of deionized water were added; the mixture was cooled down to 22° C. and the aqueous polymer dispersion obtained was filtered off via a 125 μm filter.

[0288] The dispersion had a solids content of 44.8%, a pH-value of 7.7, and an average particle size of 78 nm according to HDC.

4.3 EXAMPLE 3

[0289] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00006 380.4 g Deionized water and 40.0 g Emulsifier 1

[0290] were added in a nitrogen atmosphere and heated to 80° C. At 80° C., 30.0 g of methyl methacrylate and 3.5 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added. After 5 minutes, feed 1 and 2 were started and metered into the reaction vessel within 135 minutes; within the first 20 minutes, the polymerization temperature was increased to 87° C. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then feed 3 and 4 were metered into the reaction vessel in 45 minutes.

[0291] Feed 1:

TABLE-US-00007 15.8 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 2 (emulsion comprising): 632.4 g Deionized water 48.8 g Emulsifier 2 4.2 g Methacrylic acid 13.9 g 50% b.w. aqueous solution of acrylamide 302.6 g Methyl methacrylate 569.6 g 2-Ethylhexyl acrylate 46.6 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0292] Feed 3: [0293] 4.8 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0294] Feed 4 (Emulsion Comprising):

TABLE-US-00008 157.2 g Deionized water 22.5 g Emulsifier 2 13.8 g Methacrylic acid 226.2 g Methyl methacrylate

[0295] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 15 minutes at 87° C.; then 20.5 g of a 1.2% b.w. aqueous solution of sodium peroxodisulfate were added within 15 minutes. Subsequently, 3.4 g of a 25% b.w. aqueous solution of ammonia were added within 10 minutes and stirred in; 21.8 g of deionized water were added and stirred for another 60 minutes at 82° C. Then, 4.3 g of a 25% b.w. aqueous ammonia solution and 6 g of deionized water were added. The mixture was cooled down to 22° C. and the aqueous polymer dispersion obtained was filtered via a 125 μm filter.

[0296] The obtained polymer latex had a solids content of 48.2%, a pH-value of 8.3 and an average particle size of 103 nm according to HDC.

4.4 COMPARATIVE EXAMPLE C1

[0297] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00009 341.9 g Deionized water and 55.0 g Emulsifier 3

[0298] were added in a nitrogen atmosphere and heated to 87° C. whilst being stirred. At 80° C., 43.0 g of feed 2 and 3.2 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added, and the mixture was further heated to 87° C. 5 minutes later, feed 1 and 2 (remaining quantity) were started and metered into the reaction vessel within 120 minutes. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes.

[0299] Then, feed 3 and 4 were metered into the reaction vessel in 45 minutes.

[0300] Feed 1:

TABLE-US-00010 13.7 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0301] Feed 2 (Emulsion Comprising):

TABLE-US-00011 526.1 g Deionized water 36.7 g Emulsifier 3 8.0 g Acrylic acid 9.0 g 50% b.w. aqueous solution of acrylamide 313.0 g Methyl methacrylate 448.7 g 2-Ethylhexyl acrylate 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0302] Feed 3: [0303] 5.1 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0304] Feed 4 (Emulsion Comprising):

TABLE-US-00012 272.9 g Deionized water 13.9 g Emulsifier 3 8.0 g Acrylic acid 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 232.9 g Methyl methacrylate

[0305] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 30 minutes at 87° C.; then 5.3 g of a 25% b.w. aqueous solution of ammonia and 55.4 g of deionized water were added. The mixture was cooled down to 82° C. and stirred for 60 minutes. At the same time, 22.9 g of a 7.7% b.w. aqueous solution of hydrogen peroxide and 22.8 g of a 6.8% b.w. aqueous solution of L-Ascorbic acid were metered into the reaction vessel. After that, 15.4 g of a 7.1% b.w. aqueous ammonia solution were added; the mixture was cooled down to 22° C. and the aqueous polymer dispersion was filtered via a 125 μm filter.

[0306] The obtained polymer latex had a solids content of 44.2%, a pH-value of 7.7 and an average particle size of 68 nm according to HDC.

4.5 COMPARATIVE EXAMPLE C2

[0307] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00013 341.9 g Deionized water and 55.0 g Emulsifier 3

[0308] were added in a nitrogen atmosphere and heated to 87° C. whilst being stirred. At 80° C., 43.7 g of feed 2 and 3.2 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added, and the mixture was further heated to 87° C. 5 minutes later, feed 1 and 2 (remaining quantity) were started and metered into the reaction vessel within 120 minutes. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then, feed 3 and 4 were metered into the reaction vessel in 45 minutes.

[0309] Feed 1:

TABLE-US-00014 13.7 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0310] Feed 2 (Emulsion Comprising):

TABLE-US-00015 537.9 g Deionized water 47.1 g Emulsifier 2 8.0 g Acrylic acid 9.0 g 50% b.w. aqueous solution of acrylamide 313.0 g Methyl methacrylate 448.7 g 2-Ethylhexyl acrylate 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0311] Feed 3:

TABLE-US-00016 5.1 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0312] Feed 4 (Emulsion Comprising):

TABLE-US-00017 277.0 g Deionized water 17.9 g Emulsifier 2 8.0 g Acrylic acid 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 232.9 g Methyl methacrylate

[0313] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 30 minutes at 87° C.; then 5.3 g of a 25% b.w. aqueous solution of ammonia and 55.4 g of deionized water were added. The mixture was cooled down to 82° C. and stirred for 60 minutes. At the same time, 22.9 g of a 7.7% b.w. aqueous solution of hydrogen peroxide and 22.8 g of a 6.8% b.w. aqueous solution of L-Ascorbic acid were metered into the reaction vessel. After that, 11 g of deionized water and 4.4 g of a 25% b.w. aqueous ammonia solution were added; the mixture was cooled down to 22° C., and the aqueous polymer dispersion was filtered via a 125 μm filter.

[0314] The obtained polymer latex had a solids content of 44.6%, a pH-value of 7.4 and an average particle size of 64 nm according to HDC.

4.6 COMPARATIVE EXAMPLE C3

[0315] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00018 358.6 g Deionized water and 55.0 g Emulsifier 1

[0316] were added in a nitrogen atmosphere and heated to 87° C. whilst being stirred. At 80° C., 43.2 g of feed 2 and 3.2 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added, and the mixture was further heated to 87° C. 5 minutes later, feed 1 and 2 (remaining quantity) were started and metered into the reaction vessel within 120 minutes. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then, feed 3 and 4 were metered into the reaction vessel in 45 minutes.

[0317] Feed 1:

TABLE-US-00019 13.7 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0318] Feed 2 (Emulsion Comprising):

TABLE-US-00020 543.4 g Deionized water 24.9 g Emulsifier 1 8.0 g Acrylic acid 9.0 g 50% b.w. aqueous solution of acrylamide 313.0 g Methyl methacrylate 448.7 g 2-Ethylhexyl acrylate 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate

[0319] Feed 3:

TABLE-US-00021 5.1 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0320] Feed 4 (Emulsion Comprising):

TABLE-US-00022 281.4 g Deionized water 9.5 g Emulsifier 1 8.0 g Acrylic acid 42.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 232.9 g Methyl methacrylate

[0321] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 30 minutes at 87° C.; then 5.3 g of a 25% b.w. aqueous solution of ammonia and 55.4 g of deionized water were added. The mixture was cooled down to 82° C. and stirred for 60 minutes. At the same time, 22.8 g of a 7.7% b.w. aqueous solution of hydrogen peroxide and 22.8 g of a 6.8% b.w. aqueous solution of L-Ascorbic acid were metered into the reaction vessel. After that, 15.4 g of a 7.1% b.w. aqueous ammonia solution were added; the mixture was cooled down to 22° C., and the aqueous polymer dispersion was filtered via a 125 μm filter.

[0322] The obtained polymer latex had a solids content of 44.7%, a pH-value of 7.4 and an average particle size of 90 nm according to HDC.

4.7. COMPARATIVE EXAMPLE C4

[0323] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00023 391.2 g Deionized water and 67.7 g Emulsifier 4

[0324] were added in a nitrogen atmosphere and heated to 80° C. whilst being stirred. At 80° C., 30.0 g of methyl methacrylate and 3.5 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added. 5 minutes later, feed 1 and 2 (remaining quantity) were started and metered into the reaction vessel within 109 minutes, and the polymerization temperature was set to 87° C. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then, feed 3 and 4 were metered into the reaction vessel 52 minutes.

TABLE-US-00024 Feed 1: 14.1 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 2 (emulsion comprising): 586.8 g Deionized water 46.5 g Emulsifier 2 11.2 g Acrylic acid 9.1 g 50% b.w. aqueous solution of acrylamide 307.0 g Methyl methacrylate 445.1 g 2-Ethylhexyl acrylate 42.2 g 25% b.w. solution of ureido methacrylate in methyl methacrylate Feed 3: 6.5 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 4 (emulsion comprising): 302.2 g Deionized water 22.9 g Emulsifier 2 20.2 g Acrylic acid 54.0 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 285.8 g Methyl methacrylate

[0325] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 30 minutes at 87° C.; then 4.8 g of a 25% b.w. aqueous solution of ammonia and 60.5 g of deionized water were added and stirred for another 60 minutes. At the same time, 17.0 g of an 11.3% b.w. aqueous solution of hydrogen peroxide and 16.7 g of a 10.1% b.w. aqueous solution of L-Ascorbic acid were metered into the reaction vessel. After that, 12 g of a 25% b.w. aqueous ammonia solution and 26.6 g of deionized water were added; the mixture was cooled down to 22° C., and the aqueous polymer dispersion was filtered via a 125 μm filter.

[0326] The obtained polymer latex had a solids content of 44.3%, a pH-value of 7.5 and an average particle size of 69 nm according to HDC.

4.8. COMPARATIVE EXAMPLE C5

[0327] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

TABLE-US-00025 394.0 g Deionized water and 9.0 g Emulsifier 5

[0328] were added in a nitrogen atmosphere and heated to 80° C. whilst being stirred. At 80° C., 30.0 g of methyl methacrylate and 3.5 g of a 7% b.w. aqueous solution of sodium peroxodisulfate were added. 5 minutes later, feed 1 and 2 were started and metered into the reaction vessel within 135 minutes, and the polymerization temperature was increased to 87° C. within the first 20 minutes. After the end of feed 1 and 2, postpolymerization was effected for 5 minutes. Then, feed 3 and 4 were metered into the reaction vessel in 45 minutes.

TABLE-US-00026 Feed 1: 15.8 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 2 (emulsion comprising): 581.2 g Deionized water 1.6 g Emulsifier 7 115.2 g Emulsifier 6 4.2 g Methacrylic acid 13.9 g 50% b.w. aqueous solution of acrylamide 302.6 g Methyl methacrylate 569.6 g 2-Ethylhexyl acrylate 46.6 g 25% b.w. solution of ureido methacrylate in methyl methacrylate Feed 3: 4.8 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 4 (emulsion comprising): 149.5 g Deionized water 0.4 g Emulsifier 7 25.8 g Emulsifier 6 13.8 g Methacrylic acid 226.2 g Methyl methacrylate

[0329] After completion of feed 3 and 4, the polymerization mixture was allowed to react for 15 minutes at 87° C.; then 20.5 g of a 1.2% b.w. aqueous solution of sodium peroxodisulfate were added in 15 minutes. Subsequently, 3.4 g of a 25% b.w. aqueous solution of ammonia were added within 10 minutes and stirred in; 21.8 g of deionized water were added and stirred for another 60 minutes at 82° C. After that, 4.3 g of a 25% b.w. aqueous ammonia solution and 6 g of deionized water were added; the mixture was cooled down to 22° C., and the aqueous polymerized dispersion was filtered via a 125 μm filter.

[0330] The obtained polymer latex had a solids content of 48.1%, a pH-value of 7.9 and an average particle size of 128 nm according to HDC.

4.9 COMPARATIVE EXAMPLE C6

[0331] Example 1 was repeated with the following exceptions. [0332] i. 64.2 g of emulsifier 1 in the initial charge were replaced by 128.2 g of emulsifier 5. [0333] ii. 47.2 g of emulsifier 2 in feed 2 were replaced by 103.8 g of emulsifier 5. [0334] iii. 17.9 g of emulsifier 2 in feed 4 were replaced by 39.4 g of emulsifier 5.

[0335] The obtained polymer latex had a solids content of 45.2%, a pH-value of 8.0, and an average particle size of 71 nm according to HDC.

4.10 EXAMPLE 4

[0336] Example 1 was repeated with the following exceptions. [0337] i. 47.2 g of emulsifier 2 in feed 2 were replaced by 15.6 g of emulsifier 10. [0338] ii. 17.9 g of emulsifier 2 in feed 4 were replaced by 5.9 g of emulsifier 10.

[0339] The obtained polymer latex had a solids content of 44.4%, a pH-value of 7.8, and an average particle size of 80 nm according to HDC.

4.11 EXAMPLE 5

[0340] Example 1 was repeated with the following exceptions. [0341] i. 64.2 g of emulsifier 1 in the initial charge were replaced by 19.3 g of emulsifier 8. [0342] ii. 47.2 g of emulsifier 2 in feed 2 were replaced by 15.6 g of emulsifier 10. [0343] iii. 17.9 g of emulsifier 2 in feed 4 were replaced by 5.9 g of emulsifier 10.

[0344] The obtained polymer latex had a solids content of 44.2%, a pH-value of 7.9, and an average particle size of 96 nm according to HDC.

4.12 EXAMPLE 6

[0345] Example 1 was repeated with the following exceptions. [0346] i. 64.2 g of emulsifier 1 in the initial charge were replaced by 19.3 g of emulsifier 9.

[0347] The obtained polymer latex had a solids content of 44.2%, a pH-value of 7.6, and an average particle size of 80 nm according to HDC.

4.13 EXAMPLE 7

[0348] Example 1 was repeated with the following exceptions. [0349] i. 64.2 g of emulsifier 1 in the initial charge were replaced by 19.3 g of emulsifier 8.

[0350] The obtained polymer latex had a solids content of 45.1%, a pH-value of 0.7.6 and an average particle size of 78 nm according to HDC.

4.14 COMPARATIVE EXAMPLE C7

[0351] In a polymerization vessel equipped with metering devices and a temperature control, at 22° C.,

[0352] 701.3 g Deionized water and [0353] 30.8 g Emulsifier 5

[0354] were added in a nitrogen atmosphere and heated to 80° C. whilst being stirred. At 80° C., feed 1 was added all at once and the mixture was stirred for 2 minutes. Then feed 2 was started and metered into the reaction vessel within 40 minutes, while maintaining a temperature of 80° C. After the end of feed 2, postpolymerization was effected for 10 minutes. Then, 1.9 g of 25% b.w. aqueous ammonia was added and the mixture was stirred for 10 minutes. Then feed 3 was started and metered into the reaction vessel within 90 minutes with constant feed rate while maintaining a temperature of 80° C. 1.9 g of 25% b.w. aqueous ammonia was added 45 minutes after having started feed 3. At this point of time, feed 4 was started and metered into the reaction vessel within 45 minutes with constant feed rate while maintaining a temperature of 80° C.

[0355] Feed 1:

TABLE-US-00027 Feed 1:  70.0 g 7% b.w. aqueous solution of sodium peroxodisulfate Feed 2 (emulsion comprising): 140.1 g Deionized water  9.3 g Emulsifier 5  16.8 g Methacrylic acid 126.0 g 15% b.w. aqueous solution of methacrylamide 237.2 g Methyl methacrylate  49.0 g n-Butyl acrylate  22.5 g 25% b.w. solution of ureido methacrylate in methyl methacrylate 168.0 g 20% b.w. aqueous solution of diacetone acrylamide  11.2 g 2-Ethylhexyl thioglycolat Feed 3 (emulsion comprising): 404.0 g Deionized water  9.3 g Emulsifier 5 315.0 g n-Butyl acrylate 266.0 g 2-Ethylhexyl acrylate 140.0 g n-Butyl methacrylate 259.0 g Methyl methacrylate Feed 4:  10.0 g 7% b.w. aqueous solution of sodium peroxodisulfate

[0356] After completion of feed 3 and 4, the polymerization mixture was allowed to react at 80° C. for 90 minutes; then 5.3 g of a 25% b.w. aqueous solution of ammonia were added within 15 minutes with stirring. While being stirred, the mixture was cooled down to 22° C. At a temperature ≤40° C., 140.0 g of a 12% b.w. aqueous solution of adipic dihydrazide was added. Afterwards, the aqueous polymer dispersion was filtered off via a 125 μm filter.

[0357] The obtained polymer latex had a solids content of 42.7%, a pH-value of 8.0 and a particle size of 78 nm according to HDC.

4.15 EXAMPLE 8

[0358] Comparative example C7 was repeated with the following exceptions. [0359] i. 30.8 g of emulsifier 5 in the initial charge were replaced by 35.0 g of emulsifier 1. The amount of deionized water in the initial charge was increased from 701.3 g to 718.2 g. [0360] ii. 9.3 g of emulsifier 2 in feed 1 were replaced by 8.75 g of emulsifier 2. [0361] iii. 9.3 g of emulsifier 2 in feed 3 were replaced by 8.75 g of emulsifier 2.

[0362] The obtained polymer latex had a solids content of 42.8%, a pH-value of 8.1 and a particle size of 78 nm according to HDC.

4.16 EXAMPLE 9

[0363] Comparative example C7 was repeated with the following exceptions. [0364] i. 30.8 g of emulsifier 5 in the initial charge were replaced by 32.8 g of emulsifier 2. The amount of deionized water in the initial charge was increased from 701.3 g to 719.6 g. [0365] ii. 9.3 g of emulsifier 2 in feed 1 were replaced by 9.3 g of emulsifier 1. [0366] iii. 9.3 g of emulsifier 2 in feed 3 were replaced by 9.3 g of emulsifier 1.

[0367] The obtained polymer latex had a solids content of 43.0%, a pH-value of 8.0 and a particle size of 75 nm according to HDC.

5. APPLICATION TESTS

[0368] 5.1 Testing of Stability of Polymer Latexes Against Polyvalent Metal Salts (Test Procedure 1)

[0369] Different amounts of an aqueous solution of ZnSO.sub.4 (480 mmol/1) were added to a sample of the respective polymer dispersion. After 16 hours of storage at 22° C., the particle size (PS) was measured by means of QELS (Zetasizer Nano by Malvern). The concentration was recorded at which the particle size increased significantly (at least 2 times) compared to the starting value. The results are summarized in the following table 1.

TABLE-US-00028 TABLE 1 Stability of the Polymer Latexes against ZnSO.sub.4 Addition of salt (ZnSO.sub.4) Emulsifier: Initial PS Concentration PS Example Initial Feed (nm) (mmol/l) (nm) 1 1 2 95 17.5 250 C1 3 3 90 5 295 C2 3 2 90 8 250 C3 1 1 95 8.5 250 2 1 2 95 11 500 C4 4 2 85 5.5 500 3 1 2 103 24 500 C5 5 6 + 7 128 1 500 C6 5 5 85 10 1790 1 1 2 95 10 94 4 1 10 103 10 247 5 8 10 113 10 137 6 9 2 93 10 91 7 8 2 91 10 104

[0370] 5.2 Testing of Stability of Polymer Latexes Against Polyvalent Metal Salts (Test Procedure 2)

[0371] Firstly, stock solutions of zinc sulfate in deionized water having a defined concentration of ZnSO.sub.4 of 0.1% by weight (c=6.2 mM) and 0.05% by weight (3.1 mM) are prepared. A test tube is filled with the respective stock solution to a height of approx. 2 cm. Then one drop of the polymer latex to be tested is dropped into the test solution, and the sample is lightly shaken before evaluation. The test sample is then visually evaluated with the naked eye with regard to the formation of coagulum and rated according to the following grades. The results are summarized in the following table 2: [0372] + the polymer latex mixes completely without formation of coagulum. No coagulum can be observed when the test tube is illuminated by means of a LED torch; [0373] −/+no coagulum can be observed in daylight. However, formation of slight amounts of coagulum can be observed, when the when the test tube is illuminated by means of a LED torch; [0374] − The immediate formation of coagulum is observed in daylight without using a torch.

TABLE-US-00029 TABLE 2 Emulsifier: Initial PS Stability agains ZnSO.sub.4 Example Initial Feed (nm) 6.2 mM 3.1 mM 1 1 2 95 + + C7 5 5 78 − −/+ 8 1 2 78 −/+ + 9 2 1 75 + +

[0375] 5.3 Testing of Application Properties of Waterborne Coating Compositions

[0376] For testing the application properties of waterborne coating compositions containing the polymer latexes of examples 1 to 3 and of comparative examples C1 to C5, paint formulations were formulated using the following recipe:

TABLE-US-00030 parts by weight Demineralized water 80 Dispersant 10 Thickener 20 Defoamer 5 TiO.sub.2-Pigment 162 Filler/Extender 1 50 Filler/Extender 2 45 Reactive pigment* 20 *zinc white RS of Grillo Werke AG

[0377] The above mixture was dispersed for approx. 20 min. Then the following ingredients were added:

TABLE-US-00031 parts by weight Film former 15 Aqueous polymer latex (45%) 500 Thickener Demineralized water 93 Total 1000

[0378] Properties of the Paint Formulation:

TABLE-US-00032 Solids content (metered) (% b.w.) 52.9 Volume TiO.sub.2 (mL) 39.5 Volume Filler/Extender (mL) 38.8 Total Volume of Inorganic Ingredients (mL) 78.3 Volume Latex Polymer (mL) 211.5 PVC 27

[0379] 5.2.1 Storage Stability Test by Means of a Stormer Type Viscometer

[0380] A single point viscosity measurement was carried out according to ASTM D562 using a Stormer type viscometer measuring Krebs Units (KU). One set of measurements on the different samples in the examples were carried out 24 h after paint manufacture, the other after storing the paint sample in a closed container at 50° C. for 14 days. A difference between the two measurements of less than 5 KU units indicates good storage stability and compatibility.

[0381] 5.2.2 Tannin Blocking Effect, Film Formation and Compatibility

[0382] This test helps to determine the tannin blocking capability and film building properties of paints on an MDF (69 cm*41 cm, 1.5 cm diameter). Different tannin concentrations are applied on the MDF. 5 different concentrations are made with Tannin (high-purity grade) by Roth, Art. No. 4239.1 in demineralized water: 2.5%, 5%, 10%, 15%, and 20%. All solutions are enriched with 0.3% Betolin® V30 for enhanced squeegeeing purposes. These solutions are applied next to each other on the same MDF with a doctor blade and a 60 mμ wet layer. They are allowed to dry for 24 hrs at 22° C. and a humidity of 55%. Then a doctor blade is used to apply 300 mμ of the white paint to be tested diagonally on the strips with different tannin concentrations. The changes in color are assessed relative to the zero value (without or 0% tannin) on the larger area of the strip.

[0383] This is done as a ΔE comparison by means of a CIEL*a*b* measuring/metering device (ISO7724-2). ΔE<1 is desired, which would indicate a good tannin blocking. At a certain tannin concentration, film building failures may occur. The results are summarized in table 3.

TABLE-US-00033 TABLE 3 Application results Poly- KU KU Cracks - tannic Delta E - tannic mer Prior to After Synere- acid acid latex storage storage sis 10% 15% 10% 15% 1 107 111 No No No 0.6 0.7 2 121 122 No No No 0.5 0.6 3 108 112 No No Yes 0.8 N/A C1* 117 136 No No Yes 1.9 N/A C2* 112 123 No No Yes 1.6 N/A C3* 115 127 No No Yes 1.3 N/A C4* 109 113 No No Yes 0.8 N/A C5* 121 132 Yes, Yes Yes N/A N/A 7% *Polymer latex of Comparative Example