Low-solvent polyacrylate copolymer dispersions

Abstract

The present invention relates to an aqueous secondary copolymer dispersion comprising a copolymer (P) synthesized from a mixture of free-radically polymerizable monomers (M) comprising (M1) cycloaliphatic esters of acrylic and/or methylacrylic acid; (M2) vinyl esters of aliphatic carboxylic acids; (M3) hydroxy-functional, free-radically polymerizable monomers; (M4) carboxyl-functional, free-radically polymerizable monomers and (M5) hydroxyl- and carboxyl-free (meth)acrylic esters having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinylaromatics. The mixture further comprises glycidyl esters of aliphatic carboxylic acids. The invention also relates to a method for the production of such a dispersion, to the use of the dispersion as a coating and as a binder in 2K polyurethane coatings.

Claims

1. An aqueous secondary copolymer dispersion comprising a copolymer (P) synthesized from a mixture of free-radically polymerizable monomers (M) comprising: (M1) 0.1 weight-% to 3 weight-% of a cycloaliphatic ester of acrylic and/or methylacrylic acid, (M2) 0.1 weight-% to 3 weight-% of a vinyl ester of aliphatic carboxylic acid, (M3) 10 weight-% to 30 weight-%, of a hydroxy-functional, free-radically polymerizable monomer, (M4) 1 weight-% to 10 weight-% of a carboxyl-functional, free-radically polymerizable monomer, and (M5) 40 weight-% to 80 weight-% of a hydroxyl- and carboxyl-free (meth)acrylic ester having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinyl aromatic monomer, wherein the mixture further comprises a glycidyl ester of an aliphatic carboxylic acid in an amount of 5 weight-% to 20 weight-%, based on the total weight of the solids in the dispersion, the amounts given adding up to 100 weight-%.

2. The dispersion according to claim 1, wherein the content of solids in the dispersion is in a range of 10 weight-% to 90 weight-%, based on the total weight of the dispersion and wherein organic solvents are present in an amount of 5 weight-%, based on the total weight of the dispersion.

3. The dispersion according to claim 1, wherein in the glycidyl ester of aliphatic carboxylic acid the carboxylic acid comprises 8, 9 and/or 10 carbon atoms.

4. The dispersion according to claim 1, wherein: (M1) is isobornyl (meth)acrylate, (M2) is represented by the formula H.sub.2CCHOC(O)C(R1)(R2)(CH.sub.3) in which R1 and R2 represent saturated alkyl groups with a total of 6, 7 or 8 carbon atoms, (M3) is hydroxyethyl (meth)acrylate and/or hydroxypropyl (meth)acrylate, (M4) is (meth)acrylic acid, and (M5) is styrene, methyl (meth)acrylate and/or n-butyl (meth)acrylate.

5. A method for producing a dispersion according to claim 1, comprising the step of free-radically polymerizing a mixture of monomers (M) comprising: (M1) 0.1 weight-% to 3 weight-% of a cycloaliphatic ester of acrylic and/or methylacrylic acid, (M2) 0.1 weight-% to 3 weight-% of a vinyl esters of aliphatic carboxylic acid, (M3) 10 weight-% to 30 weight-%, of a hydroxy-functional, free-radically polymerizable monomer, (M4) 1 weight-% to 10 weight-% of a carboxyl-functional, free-radically polymerizable monomer, (M5) 40 weight-% to 80 weight-% of a hydroxyl- and carboxyl-free (meth)acrylic ester having C1 to C12 hydrocarbon radicals in the alcohol moiety and/or vinyl aromatic monomer, wherein the mixture further comprises a glycidyl esters of an aliphatic carboxylic acid in an amount of 5 weight-% to 20 weight-%, thereby obtaining a copolymer (P), said amounts based on the total weight of the solids in the dispersion, the amounts given adding up to 100 weight-%.

6. A method comprising utilizing the dispersion according to claim 1 as a coating material.

Description

EXAMPLE 1

Precursor

(1) A polyacrylate precursor was prepared using the following components:

(2) TABLE-US-00001 Component Amount [g] Part 1 Dowanol PnB 3438 Part 2 Peroxan DB 33 Dowanol PnB 33 Part 3 Styrene 570 HEMA 1601 n-Butyl acrylate 341 n-Butyl methacrylate 4294 Veova 9 1251 Part 4 Peroxan DB 118 Dowanol PnB 321

(3) Part 1 was charged to a 10 L reactor with stirrer, reflux condenser, temperature measurement and monomer feed apparatus (dropping funnel) and blanketed with a gentle stream of nitrogen for 1 hour. The batch was then heated to 148 C. with stirring. After the temperature had been reached, part 2 was added over the course of 20 minutes. Immediately thereafter, in parallel, parts 3 and 4 were metered in over 4.5 hours optionally with cooling so that the temperature did not exceed 153 C. Following complete addition, the batch was held at 148 C. for 1 hour. Cooling gave a high-viscosity resin with 68.51% by weight solids content.

EXAMPLE 2

Copolymer Dispersion

(4) A polyacrylate copolymer dispersion was prepared using the following components:

(5) TABLE-US-00002 Component Amount [g] Part 1 Cardura E10 1052 Precursor of example 1 911 (68.4 weight-% solids) Part 2 Peroxan DB 37 Part 3 MMA 3269 n-Butyl acrylate 3319 Acrylic acid 332 Part 4 Peroxan DB 108 Dowanol PnB 80 Part 5 MMA 388 HEMA 529 n-Butyl acrylate 161 Acrylic acid 176 Part 6 Peroxan DB 17 Dowanol PnB 80 Part 7 DMEA 209 Part 8 Deionized water 6231

(6) Part 1 was charged to a 30 L reactor with stirrer, reflux condenser, temperature measurement and monomer feed apparatus (dropping funnel) and blanketed with a gentle stream of nitrogen for 1 hour. The batch was then heated to 148 C. with stirring. After the temperature had been reached, part 2 was added over the course of 20 minutes. Immediately thereafter, in parallel, parts 3 and 4 were metered in over 4.5 hours, optionally with cooling. Following complete addition, the batch was held at 148 C. for 0.5 hours. Subsequently parts 5 and 6 were metered in over 1.5 hours. Subsequently the batch was held at 148 C. for an hour, then cooled to 120 C. The pressure was lowered to below 2.5 bar and a sample of 5000 g was taken. Under cooling to 95 C. part 7 was added and the mixture was stirred for 30 minutes. Finally, part 8 was added over the course of 30 minutes to carry out dispersion, followed by stirring at 80 C. for 2 hours and discharge through filters.

EXAMPLE 3

Copolymer Dispersion

(7) A polyacrylate copolymer dispersion was prepared using the following components:

(8) TABLE-US-00003 Component Amount [g] Part 1 Cardura E10 1052 Precursor of example 1 911 (68.4 weight-% solids) Part 2 Peroxan DB 47 Part 3 Styrene 476 HEMA 4371 n-Butyl acrylate 1843 Acrylic acid 302 Part 4 Peroxan DB 138 Dowanol PnB 80 Part 5 MMA 488 HEMA 929 n-Butyl acrylate 561 Acrylic acid 176 Part 6 Peroxan DB 27 Dowanol PnB 80 Part 7 DMEA 209 Part 8 Deionized water 6231

(9) Part 1 was charged to a 30 L reactor with stirrer, reflux condenser, temperature measurement and monomer feed apparatus (dropping funnel) and blanketed with a gentle stream of nitrogen for 1 hour. The batch was then heated to 148 C. with stirring. After the temperature had been reached, part 2 was added over the course of 20 minutes. Immediately thereafter, in parallel, parts 3 and 4 were metered in over 4.5 hours, optionally with cooling. Following complete addition, the batch was held at 148 C. for 0.5 hours. Subsequently parts 5 and 6 were metered in over 1.5 hours. Subsequently the batch was held at 148 C. for an hour, then cooled to 120 C. The pressure was lowered to below 2.5 bar and a sample of 5000 g was taken. Under cooling to 95 C. part 7 was added and the mixture was stirred for 30 minutes. Finally, part 8 was added over the course of 30 minutes to carry out dispersion, followed by stirring at 80 C. for 2 hours and discharge through filters.

EXAMPLE 4

Application Testing

(10) Coating formulations were prepared using the following components, the amounts given being weight parts:

(11) TABLE-US-00004 Component Comp. Ex. 4-1 Ex. 4-2 Bayhydrol A 145 40.29 Dispersion of example 2 54.53 (47.6 wt.-% solids, 3.3 wt.-%, 2 wt.-%) Dispersion of example 3 (48 wt.-% solids, 38.41 3.3 wt.-%, 2 wt.-%) Surfynol 104 BC 0.64 0.86 0.61 Disperbyk 191 98% 1.03 1.46 1.04 BYK 028 98% 0.18 0.25 0.18 Borchigel PW 25 0.16 0.22 0.16 Resiflow W 52 50% 0.49 0.66 0.47 Tronox RKB4 18.73 18.61 19.06 Schwegofoam 8333 0.70 0.94 0.66 Water 5.11 6.86 7.25 Total 67.33 84.39 67.84 Bayhydrol A 145 17.14 Dispersion of example 2 (47.6 wt.-% solids, 3.3 wt.-%, 2 wt.-%) Dispersion of example 3 (48 wt.-% solids, 16.35 3.3 wt.-%, 2 wt.-%) Total 84.47 84.39 84.19 Desmodur N 3900 75% Butoxyl 15.53 15.61 15.81 Total coating 100.00 100.00 100.00 Water for spraying viscosity 11.5 10.6 11.1 Flow time [s]: 29 31 30 OH:NCO 1:1.3 1:1.3 1:1.3 Solids [wt.-%] 52.66 54 53.74 Solvent [wt.-%] 8.18 5.23 5.1 VOC: 186 122 121 Ratio dispersion solids:pigments 1:0.725 1:0.72 1:.72 Drying time T1/T2/T3/T4 1/7.5/x 1/8/x 1/8/x Pot life [s] 0 h 30 28 31 1 h 35 29 34 2 h 3 h 49 52 67 4 h 5 h 71 gr. 120 71 6 h Gloss 20/60/Haze 0 h 1 h 79/87/ 79/88/32 82/89/ 29 23 2 h 3 h 78/87/ 78/87/29 80/8/25 30 4 h 5 h 77/88/ 58/82/ 81/90/ 37 184 21 6 h

(12) The test results for the coatings are summarized in the following table. RT=drying at room temperature, 30 60 C.=drying by storage at 60 C. for 30 minutes.

(13) TABLE-US-00005 Comp. Comp. Ex. 9-1 Ex. 9-1 Ex. 9-2 Ex. 9-2 RT 3060 C. RT 3060 C. RT 3060 C. Pendulum hardness film thickness [m] 1 d 81 119 43 81 69 126 7 d 91 137 58 96 86 147 Gloss 20/60/Haze Buchholz hardness film thickness [m] Impression resistance 1 d 66.7 83.3 62.5 76.9 62.5 76.9 7 d 66.7 100 66.7 83.3 62.5 90.9 Erichsen test Steel film thickness [m] 1 d 8.5 9.0 9.0 8.5 9.5 8.0 7 d 9.0 9.0 9.0 8.5 9.0 9.0 Pencil hardness film thickness [m] 1 d 2B HB 2B HB 2B HB 7 d HB H B-HB HB HB F MEK wiping test 1 d OK OK OK OK OK OK 7 d OK OK OK OK OK OK Thorn bending conical 7 d 0 0 0 0 0 0 Water drop water resistance film thickness [m] 16 h m5/g1-2 m5/g1 m5/g1 m4/g1 m5/ m2/g1 g1-2 32 h m5/g1 m5/g1 40 h Water resistance SD 0 d 81/89/ 81/87/ 80/88/ 79/87/ 83/90/ 82/90/ 18 18 32 28 18 24 1 d 80/88 79/87 79/80 80/89 82/69 81/89 2 d 77/86 81/89 79/88 80/88 82/89 81/88 3 d 4 d 5 d 76/83 79/87 78/81 78/86 82/89 79/87 6 d 78/86 80/88 80/89 78/86 82/89 79/87 7 d 8 d 72/85 75/84 77/88 77/87 81/88 80/87 9 d 10 d 11 d 12 d 74/83 77/86 77/87 80/88 78/88 80/88 13 d 14 d 77/85 78/87 77/86 79/8 82/89 81/84