WATERBASED BINDER FOR TWO-COMPONENT COATING COMPOSITION

Abstract

The present invention relates process for preparing an aqueous polymer dispersion by radically initiated aqueous emulsion polymerization, which comprises polymerizing, in an aqueous polymerization medium a) in a first polymerization stage 0.5 and 15 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic or dicarboxylic acid (monomers A1), 5 and 40 wt % of at least one monoethylenically unsaturated compound having at least one hydroxyl group (monomers B1), 0-40 wt % of carboxyl-free (meth)acrylic esters with a cycloaliphatic structure (monomers C1), 15 and 94.5 wt % of at least one ethylenically unsaturated compound which is different from the monomers A1, B1 and C1 (monomers D1), the amounts of the monomers A1 to D1 adding up to 100 wt %, in the presence of at least one radical initiator and at least one chain transfer agent, and also, optionally, in the presence of a dispersing assistant, with the provisos that the amount of chain transfer agent is selected such that the polymer 1 obtained from the first polymerization stage has a weight-average molecular weight in the range of 5000 and 40000 g/mol, the nature and amounts of the monomers A1 to D1 are selected such that the resulting polymer 1 has a glass transition temperature Tg.sup.1 as measured to DIN EN ISO 11357-2 (2013 September) 15 C., and thereafter polymerizing, in the presence of the polymer 1 b) in a second polymerization stage 0 and 1.0 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic or dicarboxylic acid (monomers A2), 0.1 and 40 wt % of at least one monoethylenically unsaturated compound having at least one hydroxyl group (monomers B2), 0-40 wt % of carboxyl-free (meth)acrylic esters with a cycloaliphatic structure (monomers C2) 30 and 99.9 wt % of at least one ethylenically unsaturated compound which is different from the monomers A2, B2 and C2 (monomers D2), the amounts of the monomers A2 to D2 adding up to 100 wt %, in the presence of at least one radical initiator and at least one chain transfer agent, and also, optionally, in the presence of a dispersing assistant, with the provisos that the weight ratio of the sum of the total amounts of monomers A1 to D1 (total monomer amount 1) to the sum of the total amounts of monomers A2 to D2 (total monomer amount 2) is in the range 25:75 to 50:50, the amount of chain transfer agent in the second polymerization stage is selected such that the overall polymer obtained after the second polymerization stage has a weight-average molecular weight 5000 and 75000/mol, and the amount of the dispersing assistant is 3.0 wt %, based on the sum of total monomer amount 1 and total monomer amount 2 (total monomer amount), that the sum of the total amounts of monomers C1 and C2 is 7 to 40 wt % based on the sum of total monomer amount 1 and total monomer amount 2; the aqueous polymer dispersion itself, its use and coating compositions comprising the aqueous polymer dispersion.

Claims

1.-15. (canceled)

16. A process for preparing an aqueous polymer dispersion by radically initiated aqueous emulsion polymerization, which comprises polymerizing, in an aqueous polymerization medium a) in a first polymerization stage 0.5 and 15 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic or dicarboxylic acid (monomers A1), 5 and 40 wt % of at least one monoethylenically unsaturated compound having at least one hydroxyl group (monomers B1), 0-40 wt % of carboxyl-free (meth)acrylic esters with a cycloaliphatic structure (monomers C1), 15 and 94.5 wt % of at least one ethylenically unsaturated compound which is different from the monomers A1, B1 and C1 (monomers D1), the amounts of the monomers A1 to D1 adding up to 100 wt %, in the presence of at least one radical initiator and at least one chain transfer agent, and, optionally, in the presence of a dispersing assistant, with the provisos that the amount of chain transfer agent is selected such that the polymer 1 obtained from the first polymerization stage has a weight-average molecular weight in the range of 5000 and 40 000 g/mol, the nature and amounts of the monomers A1 to D1 are selected such that the resulting polymer 1 has a glass transition temperature Tg.sup.1 as measured to DIN EN ISO 11357-2 (2013 September) 15 C., and thereafter polymerizing, in the presence of the polymer 1 b) in a second polymerization stage 0 and 1.0 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic or dicarboxylic acid (monomers A2), 0.1 and 40 wt % of at least one monoethylenically unsaturated compound having at least one hydroxyl group (monomers B2), 0-40 wt % of carboxyl-free (meth)acrylic esters with a cycloaliphatic structure (monomers C2), 30 and 99.9 wt % of at least one ethylenically unsaturated compound which is different from the monomers A2, B2 and C2 (monomers D2), the amounts of the monomers A2 to D2 adding up to 100 wt %, in the presence of at least one radical initiator and at least one chain transfer agent, and, optionally, in the presence of a dispersing assistant, with the provisos that the weight ratio of the sum of the total amounts of monomers A1 to D1 (total monomer amount 1) to the sum of the total amounts of monomers A2 to D2 (total monomer amount 2) is in the range 25:75 to 50:50, the amount of chain transfer agent in the second polymerization stage is selected such that the overall polymer obtained after the second polymerization stage has a weight-average molecular weight 5000 and 75 000/mol, and the amount of the dispersing assistant is 3.0 wt %, based on the sum of total monomer amount 1 and total monomer amount 2 (total monomer amount), that the sum of the total amounts of monomers C1 and C2 is 7 to 40 wt % based on the sum of total monomer amount 1 and total monomer amount 2.

17. The process according to claim 16, wherein the nature and amounts of the monomers A1 to D1 are selected such that the resulting polymer 1 has a glass transition temperature Tg.sup.1 in the range 15 and 75 C.

18. The process according to claim 16, wherein the amount of chain transfer agent in the first polymerization stage is selected such that the resulting polymer 1 has a weight-average molecular weight in the range of 7500 and 25 000 g/mol.

19. The process according to claim 16, wherein the amount of the dispersing assistant is 0.3 and 0.7 wt %, based on the total monomer amount.

20. The process according to claim 16, wherein the amount of chain transfer agent in the second polymerization stage is selected such that the resulting overall polymer has a weight-average molecular weight of 15 000 and 50 000 g/mol.

21. The process according to claim 16, wherein the first polymerization stage uses 5 and 10 wt % of monomers A1, 15 and 35 wt % of monomers B1, 10 and 30 wt % of monomers C1 and 45 and 70 wt % of monomers D1, and the amounts of the monomers A1 to D1 adding up to 100 wt % and the second polymerization stage uses 0 and 0.1 wt % of monomers A2, 8 and 30 wt % of monomers B2, 5 and 20 wt % of monomers C2 and 50 and 87 wt % of monomers D2 and the amounts of the monomers A2 to D2 adding up to 100 wt %.

22. The process according to claim 16, wherein the monomers of the first and second polymerization stages are each used as monomer mixtures.

23. The process according to claim 16, wherein the first and/or second polymerization stages take place in the presence of an organic solvent having an evaporation number 20, as determined to DIN 53170 (2009 August).

24. The process according to claim 22, wherein at least part of the monomer mixtures in each case is metered into the aqueous polymerization medium under polymerization conditions.

25. The process according to claim 23, wherein the total amount of the organic solvent is 1 and 25 wt %, based on the total monomer amount.

26. An aqueous polymer dispersion obtainable by a process according to claim 16.

27. A method comprising providing the aqueous polymer dispersion according to claim 26 and incorporating the dispersion as a binder in the production of coatings, adhesives, sealants, synthetic resin renders, papercoating slips, nonwoven fiber webs, flexible roof coatings, and industrial and architectural coatings, and also in sand consolidation, as a component in the production of textile assistants or leather assistants, and impact modifier, or for the modification of mineral binders and plastics.

28. An aqueous formulation comprising an aqueous polymer dispersion according to claim 26 and at least one component selected from the group comprising polyisocyanate, melamine-formaldehyde resin, and urea-formaldehyde resin.

29. A method comprising providing the aqueous formulation according to claim 28 and including the formulation as a component in the production of coating formulations.

30. A coating composition comprising at least one aqueous polymer dispersion according to claim 26 as binder, optionally at least one other binder, different from the aqueous polymer dispersion of the invention, at least one crosslinker selected from the group consisting of polyisocyanates, melamine-formaldehyde resins, and urea-formaldehyde resins, optionally at least one pigment, and optionally at least one corrosion inhibitor.

Description

EXAMPLE 1 (E1INVENTIVE)

[0258] A 2 l-polymerization vessel equipped with metering devices and temperature regulation was charged at 20 to 25 C. (room temperature) under a nitrogen atmosphere with [0259] 301.2 g of deionized water and [0260] 6.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate

[0261] and this initial charge was heated to 80 C. with stirring. When this temperature had been reached, 11.0 g of feed 1 were added, followed by metered addition of 25.7 g of a 7% strength by weight aqueous solution of sodium peroxodisulfate over the course of 5 minutes, after which the batch was stirred at the aforementioned temperature for 5 minutes more.

[0262] Subsequently, with the temperature of 80 C. maintained, the remainder of feed 1 was metered in continuously over the course of 40 minutes at a constant flow rate. Thereafter the polymerization mixture was left to react for another 10 minutes at 80 C. After that, first 12.0 g of deionized water and subsequently 2.3 g of an 8% strength by weight aqueous ammonia solution were added. Thereafter, feed 2 was metered in continuously over the course of 90 minutes at a constant flow rate. 40 minutes after the start of feed 2, 3.5 g of a 10% strength by weight aqueous ammonia solution were added. After the end of feed 2, the polymerization mixture was left to react at 80 C. for 90 minutes more, and then 85.1 g of deionized water were added to the polymerization mixture. Thereafter the aqueous polymer dispersion obtained was cooled to room temperature and filtered through a 50 m filter.

[0263] Feed 1 (homogeneous mixture of): [0264] 56.3 g of deionized water, [0265] 3.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate, [0266] 4.5 g of 2-ethylhexyl 2-mercaptoethanoate, [0267] 10.8 g of Solvesso 100 [aromatics-containing organic solvent from Exxon Mobil], [0268] 10.8 g of butyl glycol, [0269] 30.2 g of n-butyl acrylate, [0270] 13.5 g of styrene, [0271] 37.73 g of methyl methacrylate, [0272] 13.57 g of isobornyl methacrylate, [0273] 8.6 g of methacrylic acid, and [0274] 32.1 g of 2-hydroxyethyl methacrylate

[0275] Feed 2 (homogeneous mixture of): [0276] 69.4 g of deionized water, [0277] 6.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate, [0278] 1.8 g of 2-ethylhexyl 2-mercaptoethanoate, [0279] 25.2 g of Solvesso 100, [0280] 25.2 g of butyl glycol, [0281] 150.8 g of n-butyl acrylate, [0282] 76.31 g of methyl methacrylate, [0283] 31.67 g of isobornyl methacrylate, and [0284] 59.7 g of 2-hydroxyethyl methacrylate

[0285] The resulting polymer dispersion had a solids content of 41.8 wt %. The mean particle diameter of the dispersion particles obtained was 163 nm. The hydroxyl number of the dispersion polymer was found to be 86 mg of KOH/g.

[0286] A 0.5 ml sample was taken from the reaction mixture immediately before the start of feed 2, and the weight-average molecular weight of the polymer from the first polymerization stage was found to be 10200 g/mol and the T.sub.g measured was 23.4 C. The overall polymer obtained in the dispersion had a weight-average molecular weight of 31600 g/mol.

COMPARATIVE EXAMPLE 1 (CE 1)

[0287] Comparative example 1 was prepared entirely in analogy to the preparation of inventive example 1, with the difference that the monomer composition of feed 1 and feed 2 was according table 1.

INVENTIVE EXAMPLES 2-6 (E2-E6)

[0288] Inventive examples 2-6 were prepared entirely in analogy to the preparation of inventive example 1, with the monomer composition of feed 1 and feed 2 was according table 1.

TABLE-US-00001 Example CE 1 E2 E3 E4 E5 E6 Monomers in feed 1 n-butyl acry- 30.2 g 30.2 g 30.2 g 30.2 g 30.2 g 30.2 g late styrene 13.5 g 13.5 g 13.5 g 13.5 g 13.5 g 13.5 g methyl meth- 51.3 g 24.16 g 37.73 g 24.16 g 37.73 g 24.16 g acrylate IBOMA 27.14 g/ 6 pphm CHMA 13.57 g/ 27.14 g/ 3 pphm 6 pphm IPhMA 13.57 g/ 27.14 g/ 3 pphm 6 pphm methacrylic 8.6 g 8.6 g 8.6 g 8.6 g 8.6 g 8.6 g acid 2-hydroxyethyl 32.1 g 32.1 g 32.1 g 32.1 g 32.1 g 32.1 g methacrylate Monomers in feed 2 n-butyl acry- 150.8 g 150.8 g 150.8 g 150.8 g 150.8 g 150.8 g late methyl meth- 108.0 g 44.65 g 76.31 g 44.65 g 76.31 g 44.65 g acrylate IBOMA 63.31 g/ 14 pphm CHMA 31.67 g/ 63.31 g/ 7 pphm 14 pphm IPhMA 31.67 g/ 63.31 g/ 7 pphm 14 pphm 2-hydroxyethyl 59.7 g 59.7 g 59.7 g 59.7 g 59.7 g 59.7 g methacrylate Solid content 42.8 41.9 43.8 43.7 42.4 42.5 [wt %] mean particle 139 126 123 122 116 107 diameter [nm] M.sub.w 1.sup.ststage 10100 9910 12300 10800 11900 11900 [g/mol] T.sub.g.sup.1 1.sup.ststage 22.7 23.6 20.6 18.5 19.3 18.9 polymer.sup.2) [ C.] M.sub.w final 36600 34300 39400 33900 39100 38600 [g/mol] Hydroxyl 86 86 86 86 86 86 number.sup.1) mg KOH/g polymer pphm: parts per hundred monomer (sum of total monomer amount 1 and total monomer amount 2) .sup.1)calculated .sup.2)measured

USE EXAMPLES

[0289] The polymer dispersions obtained in inventive examples 1, 2, 3 and 4 and in comparative examples 1 were adjusted to a solids content of 41.0 wt % by dilution with deionized water. Aqueous formulations were produced from the aqueous polymer dispersions thus obtained, by the following procedure.

[0290] Test Methods:

[0291] Cotton wool drying time: The coating composition was applied with a draw down bar on a glass plate to get a wet film thickness of 150 m. After film application, a frayed cotton wool was swept without pressure across the surface of the coating every 5 to 10 minutes. At the beginning, cotton fibers were sticking to the coating. The time when no fibers remained attached to the coating, is referred to as the cotton wool drying time.

[0292] Sand through drying time: The coating composition was applied with a draw down bar on two glass plates to get a wet film thickness of 150 m. A cylindrical funnel mounted on two small metal wheels, one on each side of the funnel outlet, was quickly placed on the glass plates with the wet film. The cylindrical funnel on wheels moves at constant velocity of 1 cm per hour over the wet film. When the film is not through-cured, the wheels leave marks on the film. When the film is through-cured, the wheels leave no marks on the film anymore. The length (1 cm length refers to 1 hour) of the marks of the wheels in the coating is referred to as sand through drying time.

[0293] Pendulum hardness [osc.]: The coating composition was applied with a draw down bar (gap=150 m) on a 4 mm thick glass plate, which has been cleaned with acetone before, yielding a wet film. The coated glass plates were dried at 23 C., and the pendulum hardness was measured after 2 h, 4 h, 1 d, 7 d. After 7 days, the glass plates were additionally heated to 40 C., or 60 C. respectively (cf., tables) for 15 hours, and after cooling to 23 C., the pendulum hardness was measured again. The pendulum hardness was measured according to DIN EN ISO 1522:2006 using the Knig pendulum.

[0294] Preparation of Formulations:

EXAMPLES SERIES 1CLEARCOATS USING BASONAT HW 3280 MBA (HYDROPHILICALLY-MODIFIED POLYISOCYANATE BASED ON HDI AND IPDI)

[0295] Formulation:

[0296] Formulation of Component A:

[0297] All components were added under mixing. The pH-value of 100 g of the inventive dispersion was adjusted to 8-8.5 by adding a 1:1 mixture of dimethylethanolamine (DMEA):water. Deion. water is added in an amount that the final component A shows a solids content of 39% by weight. Subsequently, 1.29 g of Hydropalat WE 3650 (from BASF; wetting agent) and 0.43 g of EFKA SL 3035 (from BASF; slip/leveling agent) was added. The mixture was stirred at 400 rpm for 5 minutes, and then was left standing overnight to give the readily formulated component A.

[0298] Formulation of Component B:

[0299] As component B, Basonat HW 3280 MBA (from BASF; hydrophilically-modified polyisocyanate based on HDI and IPDI) was used as delivered.

[0300] Formulation of the Two-Component Clearcoat:

[0301] Under mixing at 600 rpm, to 50 g of component A, 12 g of component B (corresponds to an index of 100, i.e., 1 NCO group of hardener on 1 OH group of binder) was added. The mixture was stirred at 1200 rpm for 2 minutes. Subsequently, 4 g of deion. water was added under mixing at 600 rpm. The mixture was stirred for 30 seconds at 600 rpm to give the clear coat at a solids content of ca. 44% by weight, which can be applied after waiting for 30 minutes.

TABLE-US-00002 TABLE 2 Pendulum hardness and drying times of Clearcoats with Dispersions CE1, E1-E6 and Basonat HW 3280 MBA (hydrophilically modified polyisocyanate based on HDI and IPDI) Sand Cotton Pendulum hardness [osc.] through wool after 2 h/4 h/1 d/7 d/7 d Clear- drying drying at room temperature and coat No. Dispersion [h] [min] additionally 15 h at 40 1 n.i CE1 3.5 40 5/7/18/48/77 2 E1 4.5 25 2/6/18/47/79 3 E2 2.0 25 3/6/23/56/99 4 E3 3.5 25 4/6/20/51/78 5 E4 4.0 30 3/6/20/50/77 6 E5 4.0 24 3/7/16/36/48 7 E6 4.0 25 3/8/22/49/69 n.i.: Not according the invention

[0302] All examples according the invention show a very good drying time on cotton wool despite they are in equivalent monomer profiles.

EXAMPLESSERIES 2: CLEARCOATS WITH USAGE OF INVENTIVE DISPERSION IN COMBINATION WITH A BASONAT HI 2000 NG (LOW-VISCOUS HDI-BASED POLYISOCYANATE)

[0303] Formulation:

[0304] Formulation of Component A:

[0305] All components were added under mixing. The pH-value of 100 g of the inventive dispersion was adjusted to 8-8.5 by adding a 1:1 mixture of dimethylethanolamine (DMEA):water. Deion. water is added in an amount that the final component A shows a solids content of 39% by weight. Subsequently, 1.29 g of Hydropalat WE 3650 (from BASF; wetting agent) and 0.43 g of EFKA SL 3035 (from BASF; slip/leveling agent) was added. The mixture was stirred at 400 rpm for 5 minutes, and then was left standing overnight to give the readily formulated component A.

[0306] Formulation of Component B:

[0307] Under mixing at 600 rpm, Basonat HI 2000 NG (from BASF; low viscous HDI-based polyisocyanate) was dissolved in Rhodiasolv RPDE (from Solvay; mixture of dimethyl glutarate, dimethyl succinate, and dimethyl adipate) to give a 65% by weight solution. The mixture was mixed for 2 minutes at 600 rpm.

[0308] Formulation of the Two-Component Clearcoat:

[0309] Under mixing at 600 rpm, to 100 g of component A, 29.3 g of component B (corresponds to an index of 150, i.e., 1.5 NCO groups of hardener on 1 OH group of binder) was added. The mixture was stirred at 1200 rpm for 2 min to give the clear coat at a solids content of ca. 45%, which can be applied after waiting for 30 min.

TABLE-US-00003 TABLE 3 Pendulum hardness of Clearcoats with Dispersions CE1, E1-E6 and a polyisocyanate as hardener (Basonat HI 2000 NG) Pendulum hardness [osc.] after 2 h/4 h/1 d/3 d/7 d/7 d at room Clearcoat No. Dispersion temperature + 15 h at 60 1 n.i CE1 1/2/19/61/76/85 2 E1 1/2/24/66/77/94 3 E2 1/2/24/76/97/106 4 E3 2/2/22/61/83/86 5 E4 1/2/19/63/82/90 6 E5 0/0/15/20/42/52 7 E6 0/0/17/22/45/60 n.i.: Not according the invention