EP2992059A1

EP2992059A1 - Application of a silicone composite in water-based coatings

Info

Publication number: EP2992059A1
Application number: EP14723369.6A
Authority: EP
Inventors: Shenggang SHA
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2013-05-04
Filing date: 2014-04-28
Publication date: 2016-03-09
Also published as: CN104130620A; WO2014180690A1

Abstract

The present invention relates to a silicone composite, which could be used in water based coatings as a pH regulator.

Description

Application of a silicone composite in water-based coatings Technical Field

This invention relates to a silicone composite. The composite in this invention can be used to adjust the pH value in water-based architectural coatings. Technical Background

pH regulators (Acidity regulators, or pH control agents) are commonly used additives in water-based architectural coatings.

Although with low amount, they are indispensable for keeping the stability of the coatings.

It is well known that a small amount of polymerizable acrylic acid or methacrylic acid is normally added when synthesizing polymer dispersions and after polymerization, a small amount of pH regulator is needed to keep the dispersions slightly alkaline.

In the process of water-based architectural coating preparation, the cellulose in the formulations would be better dissolved under a slightly alkaline condition.

Normally the alkali swelling emulsion thickener in the formulations is acidic. Only after alkaline pH regulator is added and polymer carboxylate is formed can it function as a thickener.

Besides, slightly alkaline water-based coating will not get corrupted easily . When canned in iron wares , slightly alkaline coating can decelerate the corruption of the iron tins .

Common pH regulators in water-based coatings are as follows: potassium hydroxide (or sodium hydroxide) , ammonia, monoethanol amine, diethanolamine , triethanolamine ,

2-amino-2-methyl-l-propanol and 2-amino-2-ethyl-l, and

3 -propanediol . However, all of these products have more or less disadvantages. Potassium hydroxide (or sodium hydroxide) is cheap and without VOC, but it will decrease the water resistance and scrubbing resistance of the coating. Ammonia and organic amine are of special unpleasant smell which fails to meet the requirements of low or zero VOC in the coating. 2 -amino-2 -methyl -1-propanol (brand name AMP95) is expensive which restricts its extensive application in the architectural coating area.

As revealed by present technology, adding a small amount of potassium methylsiliconate as pH regulator into water-based architectural coatings can improve the scrubbing resistance of the coating. Besides, it has no VOC or smell.

The purpose of this invention is to obtain a pH regulator which is able to adjust pH value stably, safe and environment friendly, cheap and able to improve the scrubbing resistance of the water-based architectural coating. Invention Descriptions

Within this invention, it is accidentally discovered that the composite obtained by combining alkylsilanol metal salt and functional silane can significantly increase the scrubbing resistance of the water-based architectural coating and meanwhile it has no VOC or smell, and is also cheap. The composite as defined in this invention is mainly used in water-based architectural coatings and it can be also used in water-based polymer emulsions, water-based inks, water-based adhesives and water-based wood coatings etc.

The technical scheme of this invention is summarized as follows:

The application of a silicone composite in water-based coatings, of which the silicone composite contains alkylsilanol metal salt and functional silane, in which

The general formula of the alkylsilanol metal salt as defined is R^i (OH) ₂OM, in which R¹ is C1-C4 alkyl or alkene; M is alkali metal,

The general chemical formula of the functional silane as defined is (R²0) _a (R³)_bSi R⁴; in which, R², R³ are C1-C6 alkyl, preferably C1-C2 alkyl, R² and R³ can either be the same or different, a is 1 or 2 or 3, b is 0,1 or 2; R⁴ is a functional group containing nitrogen, preferably functional groups containing primary amines and/or 1-3 secondary amines, preferably functional groups containing propyl, 1 primary amine and/or 1 secondary amine, preferably the ones with structural formula from -C₃H_eNHCONH₂ , -C₃H₆NH₂, - C3H6 HC2H4NH2 .

The application as defined above, the alkylsilanol metal salt in the composite, R¹ is C1-C4 alkyl, preferably methyl , ethyl and propyl, most preferably methyl or ethyl; M is sodium or potassium, preferably potassium .

The application as defined above, in which the functional silane is preferably silane with boiling point higher than 250^°C, which is one of the following or a mixture of several from the following: N- ( - 2 -aminoethyl) (3-aminopropyl) trimethoxy silane,

N- ( -2-aminoethyl) (3 -aminopropyl) triethoxy silane,

N- ( -2 -aminoethyl) (3 -aminopropyl) methyl dimethoxy silane,

N- (-2-aminoethyl) (3-aminopropyl) methyl diethoxy silane,

(3-aminopropyl) trimethoxy silane, (3-aminopropyl) triethoxy silane, (3-aminopropyl) methyl dimethoxy silane, (3-aminopropyl) methyl diethoxy silane, (3 -ureidopropyl) trimethoxy silane,

(3 -ureidopropyl) triethoxy silane, (3 -ureidopropyl)

methyldimethoxy silane , (3 -ureidopropyl) methyldiethoxy silane.

The application as defined above, in the composite, the alkylsilanol metal salt is 1-99%, based on total weight of the water-based pH regulator, preferably 15-60%; most preferably 15-35% (w/w) .

The application as defined above, in the composite, the functional silane is 0.1-99%, based on total weight of the water-based pH regulator, preferably 1-20%; most preferably 1-5% (w/w) .

The application as defined above, the composite also contains 0.1-10% potassium hydroxide or sodium hydroxide.

The application as defined above, the silicone composite is 0.05-1

% of the water-based architectural coating, preferably 0.1-0.5 % (w/w) . The application as defined above, the water-based architectural coatings include vinyl acetate-ethylene coating system, styrene acrylic coating system, pure acrylic coating system, silicone-acrylic coating system and vinyl acetate-acrylic coating system.

The preparation process of the pH regulator as defined in this invention is relatively easy. Simply mix the alkylsilanol metal salt and the functional silane under room temperature, and add potassium hydroxide or sodium hydroxide or potassium hydroxide water solution or sodium hydroxide water solution as needed.

Prepare water-based architectural coating by regular methods , add pH regulator into coating under room temperature and mix well .

Embodiment Examples

The amount in the following embodiment examples is referred to weight unless otherwise stated.

Potassium methylsiliconate CH₃Si (OH) ₂OK, brand name SILRES^® BS16 , is a water solution that contains 54%(w/w) potassium

methylsiliconate, from Wacker Chemie AG;

N- ( -2-aminoethyl) (3 -aminopropyl) trimethoxy silane, brand name GENIOSIL^® GF 91, from Wacker Chemie AG;

N- ( -2 -aminoethyl) (3 -aminopropyl) methyl dimethoxy silane, brand name GENIOSIL^® GF 95, from Wacker Chemie AG;

(3 -aminopropyl) trimethoxy silane, brand name GENIOSIL^® GF 96, from Wacker Chemie AG;

(3 -aminopropyl) triethoxy silane , brand name GENIOSIL^® GF 93 , from

Wacker Chemie AG;

(3-ureidopropyl) trimethoxy silane, brand name GENIOSIL^® GF 98, from Wacker Chemie AG;

The viscometer used in this invention is "KU-2 Viscometer" from BROOKFIELD, the unit of the values in all the tables is KU. The instrument for measuring pH value is the "lab pH meter" from METTLER TOLDO . The scrubbing resistance tester REF 903 from SHEEN is used in this invention and the protocol in ASTM D2486-2006 is followed to test the scrubbing resistance. Preparation of pH regulator comparison example

Mix 2 parts of potassium hydroxide, 18.9 parts of potassium methylsiliconate (prepared by using SILRES^® BS16) and the rest parts of water under room temperature to get a colorless transparent solution, which is pH regulator comparison example 1.

Mix 3 parts of potassium hydroxide, 20 parts of potassium methylsiliconate (prepared by using SILRES^® BS16) and the rest parts of water under room temperature to get a colorless transparent solution which is pH regulator comparison example 2.

AMP 95, from the DOW Chemical Company, is a water solution containing 95 % (w/w) 2 -amino-2 -methyl-1-propanol . It is the best pH regulator in the current commercial coating area and is set as pH regulator comparison example 3.

Preparation of pH regulator embodiment example

Mix about 18-55 parts of alkylsilanol metal salt (which can be made from water solutions of potassium methylsiliconate, sodium methylsiliconate, etc.), about 1-50 parts (preferably 1-3 parts) of functional silane (which includes N- ( -2-aminoethyl) (3-aminopropyl) trimethoxy silane, N- ( -2 -aminoethyl ) (3 -aminopropyl ) methyl dimethoxy silane, (3-aminopropyl) trimethoxy silane,

(3-aminopropyl) triethoxy silane, (3 -ureidopropyl) trimethoxy silane, etc.) (the amount of functional silane can be increased to 50-99 %(w/w) in certain embodiment examples), about 0.5-4 parts of potassium hydroxide or sodium hydroxide and the rest amount of water to get the pH regulator embodiment example in this invention.

Prepare the pH regulator examples 1-13 and 17-23 according to the above steps and the recipes listed in Table 1, 2 and 3. The pH regulator examples 1-13 and 17-23 prepared in this invention are colorless transparent solutions with stable characters and odorless .

Potassium methyl silicate mentioned in Table 1, 2 and 3 is referred to pure material. But Potassium methyl silicate is added to pH regulator samples as its water solution during preparation, such as SILRES^® BS16. In Table 1, 2 and 3, KOH and NaOH are referred to pure material which can be also added in the form of KOH/NaOH water solution during preparation.

Table 1 pH pH pH PH PH pH regulator regulator regulator regulator regulator regulator comparison Exam le 1 Example 2 Example 3 Example 4 Example 5 Example 1

KOH 2 2 2 2.7 2.7 2.3

Potassium 18.9 18.9 18.9 18.9 20 20.3 methyl

siliconate

Water appropriate appropriate appropriate appropriate appropriate appropriate amount amount amount amount amount amount

GENIOSIL^® GF 95 0.5 1 1 1.2 5

Total amount 100 100 loo 100 100 100

_iilFtlnuncoasnea

Wa l l241-S / Bu

Table 2 pH pE pH pH pH PH pH pH regulator regulator regulator regulator regulator regulator regulator regulator Example 6 Example 7 Exam le 8 Example 9 Example 10 Example 11 Example 12 Example 13

NaOH 3.3

OH 3 3.15 3 3 3 3

Potassium 20 20 20 20 20 20 20 53.4 methyl

siliconate

Water appropriate appropriate appropriate appropriate appropriate appropriate appropriate appropriate amount amount amount amount amount amount amount amount

GENIOSIL 1.2 1.2 1.2 1.2 ®GF 95

GENIOSIL 1.2

®GF 91

GENIOSIL 1.2

®GF9

GENIOSIL 1.2

®GF96

GENIOSIL 1.2

®GF98

Total amount 100 100 100 100 100 100 100 100

Table 3

A typical water-based architectural coating preparation method is as follows:

add about 0.4 parts of hydroxyethylcellulose into about 20-40 parts of water, mix well, add about 0.6 parts of dispersant, stir mix until totally dispersed, then add about 0.2 parts of wetting agent , about 0.15 parts of defoaming agent, about 10-25 parts of titanium dioxide pigments, about 7 parts of calcined kaolin, about 8 parts of talc and about 20 parts of heavy calcium carbonate in the above order, disperse at high speed for 10-20 min (2000 rpm) , then at low speed for 5-10 min (800 rpm) , then add about 0.2 parts of pH regulator, about 10-25 parts of film forming emulsions (including vinyl acetate-ethylene emulsions, styrene acrylic emulsions, acetate-acrylic emulsions etc.), about 0.2 parts of preservatives, about 1.0 parts of antifreeze, about 0.15 parts of defoaming agent, about 0.5 parts of thickener and the rest amount of water in the above order, stir at low speed for 5-10 min (800 rpm) , then get the water-based architectural coating. Mix the pH regulator 1, 2 listed in Table 1 and other ingredients in the following table according to the preparation method mentioned above and stir well to get coating example 1, coating example 2 and coating comparison example 1.

Coating system 1, vinyl acetate-ethylene VAE emulsion system

Ingredients Weight (parts)

Water 34

hydroxyethylcellulose 250HBR (Ashland) 0.4

Polyacrylate ammonium dispersant Lopon® 885 (BK 0.6

Giulini)

Wetting agent Genapol^® BE 2410 (Clariant) 0.2

SILFOAM^® SD 860 (Wacker) 0.15

Titanium dioxide Ti-Pure^® R-706 (DuPont) 12 Calcined kaolin CK-400 (Jiaoling Guangfu) 7

800 mesh talc 8

5 urn heavy calcium carbonate 20

pH regulator 0.2

vinyl acetate-ethylene VAE emulsion VINNAPAS® 12

EF718

Isothiazolinone preservative Kathon^® LXE (DOW) 0.2

1 , 3 -propanediol 1

SILFOAM^® SD 860 (WACKER) 0.15

Hydrophobic modified alkali soluble thickener 0.5

Rheolate 430 (Elementis)

Water 3.6

Total amount 100.00

Film forming emulsions, brand name VINNAPAS^® EF718, is from Wacker Chemie AG, vinyl acetate-ethylene polymer dispersions, solid content 55 % (w/w) , density 1.07g/mL, viscosity 150-650mPa»s (Brookfield Viscometer No. 2 rotor 60 rpm)

The coating example 1 and 2, which are made in coating system 1 and the coating comparison example 1 are stored in oven for 30 day under 50^°C, then measure the stability. See the following table for the viscosity stability and pH stability of the system:

Initial Initial pH viscosity pH value

viscosity value after 50°C after 50°C (KU) 30day 30day

storage storage

Coating 119.2 7.6 113.5 7.65 comparison

example 1

Coating 113.5 7.57 105.7 7.65 example 1

Coating 119 7.55 107.8 7.75 example 2

The stability of the coating example 1 and coating example 2, which containing the composite of potassium methyl silicate and functional silane, is good. After one month storage under 50°C, the change of viscosity is within +5KU, which is in compliance with the national standard.

Test results of the wet scrubbing resistance of these samples are as follows

It shows that the scrubbing resistance of the coating products (Coating examples 1 and 2) can be significantly improved by adding the composite of potassium methyl silicate and functional silane. There is a significant improvement of scrubbing resistance compared with the coating comparison example 1 in which only potassium methyl silicate is added. Increasing the amount of functional silane in a certain range can significantly improve the scrubbing resistance of the product . Coating system 2, vinyl acetate-ethylene VAE emulsion system

Ingredients Weight

(parts)

Water 34.3 hydroxyethylcellulose 250HBR 0.4

Polyacrylate ammonium dispersant Lopon^® 885 0.6

Wetting agent Genapol^® BE 2410 (Clariant) 0.2

Defoaming agent SILFOAM^® SD 860 0.15

Titanium dioxide Ti-Pure^® R-706 (DuPont) 12

Calcined kaolin CK-400 7

Talc 800 mesh 8

1500 mesh heavy calcium carbonate CC1500 15

Preservative Kathon^® LXE 0.2

Antifreeze propanediol 1.5 pH regulator , 0.2

Vinyl acetate-ethylene VAE emulsions VINNAPAS^® EZ 20

3010

Defoaming agent SILFOAM^® SD 860 (Wacker) 0.15

Hydrophobic modified alkali soluble thickener 0.3 ACRYSOL^® TT-935 (DOW)

Water 1.3

Total amount 100

VINNAPAS^® EZ 3010 is vinyl acetate-ethylene polymer emulsion from Wacker Chemie AG, normal viscosity 2700-5900 mPa . s , density 1.06g/ cm³.

Add pH regulator examples 6-13 in Table 2 into coating system 2 to get coating examples 6-13, respectively, the storage stability of which are shown in the following table. Add pH regulator comparison example 2 into coating system 2 to get coating comparison example 2.

Coating examples 6-13 all possess good pH stability; after one month storage in 50^°C, the change of viscosity is within +5KU, which is in compliance with the national standard.

Scrubbing resistance data are shown below:

Average wet scrubbing cycles

Coating example 6 694

Coating example 7 700

Coating example 8 877

Coating example 9 980

Coating example 10 503

Coating example 11 1960

Coating example 12 642 Coating example 13 880

Coating comparison example2 480

Although the scrubbing resistance of coating examples 10 and 12, into which GENIOSIL^® GF93 and GENIOSIL^® GF98 are added respectively, are not as good as the other coating examples, they are still better than coating comparison example 2. The performance of coating example 11, into which GENIOSIL^® GF96 is added, is unexpectedly good.

Add pH regulators 17-23 in Table 3 into coating system 2 to get coating examples 17-23 respectively. The storage stability is shown as follows:

Scrubbing resistance data of coating examples 17-23 and coating comparison example 2 are as follows: Average wet scrubbing cycles

Coating example 17 915

Coating example 18 1306

Coating example 19 1390

Coating example 20 1008

Coating example 22 1010

Coating example 23 1098

Coating comparison example2 480

By comparing coating examples 17-23 with coating examples 6-13, it is found that the scrubbing resistance can be significantly improved by increasing the amount of potassium methylsiliconate and functional silane in the coating system.

Coating system 3, vinyl acetate-ethylene VAE emulsions system

Ingredients Weight

(part)

Water 26 hydroxyethylcellulose 250 HBR 0.4

Polyacrylate ammonium dispersant Lopon^® 885 0.6

Wetting agent Genapol^® BE 2410 (Clariant) 0.2

SILFOAM^® SD 860 0.15

Titanium dioxide Ti-Pure^® R-706 (DuPont) 22

Calcined kaolin CK-400 7

1500 mesh heavy calcium carbonate 8

Preservative Kathon^® LXE 0.2

Antifreeze propanediol 1.5

pH regulator 0.2

Vinyl acetate-ethylene VAE emulsions VINNAPAS® 29

EZ3010

SILFOAM^® SD 860 (Wacker Chemie AG) 0.15 ACRYSOL^® TT-935 hydrophobic modified alkali 0.3

soluble thickener (DOW)

Water 4.3

Total amount 100.00

VINNAPAS^® EZ 3010 is vinyl acetate-ethylene polymer emulsion from Wacker Chemie AG, normal viscosity 2700-5900 mPa.s, density

1.06g/cm³.

Add pH regulator example 3 in Table 1 and pH regulator comparison example 3 in Table 3 into coating system 3 to get coating example 3 and coating comparison example 3, respectively.

Stability test results:

Wet scrubbing resistant cycles:

The scrubbing resistance of coating example 3 prepared according to this invention is better than coating comparison example 3 which is prepared using the best pH regulator AMP95 in the current market. Coating system 4, acetate-acrylic emulsions system

Ingredients Weight

(part)

Water 33.15

hydroxyethylcellulose 250 HBR 0.35

Polyacrylate ammonium dispersant Lopon^® 885 0.5

Wetting agent Genapol^® BE 2410 (Clariant) 0.2

SILFOAM^® SD 860 0.15

Titanium dioxide Ti-Pure^® R-706 (DuPont) 12

Calcined kaolin CK-400 7

Talc 800 mesh 8

1500 mesh heavy calcium carbonate 20

Preservative Kathon^® LXE 0.2

1 , 3 -propanediol 1

pH regulator 0.2

NaPoly^® 7188 acetate-acrylic dispersions 14

(Henkel)

2,2,4-trimethyl-1,3 -pentanediol 1

monoisobutyrate Texanol^® (Eastman)

SILFOAM^® SD 860 0.15

Alkali soluble thickener HISOL® D105 (Nae Woi 0.5

Korea)

Water 1.6

Total amount 100

NaPoly^® 7188 acetate-acrylic dispersion is solid content 55 % (w/w) , normal viscosity 500-2000 mPa.s, density 1. lg/ cm³.

Add pH regulator examples 4 and 5 in Table 1 and pH regulator comparison example 3 in Table 3 into coating system 4 to get coating examples 4 and 5 and coating comparison examples 4, respectively. Coating Coating Coating

comparison example 4 example 5

example 4

Average wet 101 130 143

scrubbing cycles

In coating system 4 (acetate-acrylic system) , when the same amount is used, the scrubbing resistance of coating examples 4 and 5 which containing pH regulators from this invention is much better than coating comparison example 4 which containing AMP 95 as pH regulator. The performance can be improved by 30 % or more.

Claims

1. The application of a silicone composite in water-based coatings, of which the silicone composite contains alkylsilanol metal salt and functional silane, in which

the general formula of the alkylsilanol metal salt as defined is R¹Si(OH)₂OM, in which R¹ is C1-C4 alkyl or alkene; M is alkali metal, the general chemical formula of the functional silane as defined is (R²0) _a (R³)_bSiR⁴; in which R², R³ are C1-C6 alkyl, R² and R³ can either be the same or different, a is 1 or 2 or 3, b is 0, 1 or 2; R⁴ is a functional group containing nitrogen.

2. The application according to claim 1, in which R⁴ has the meaning of functional groups containing primary amines and/or 1-3 secondary amines, preferably functional groups containing propyl, 1 primary amine and/or 1 secondary amine.

3. The application according to claim 1, the alkylsilanol metal salt in the composite, R¹ is C1-C4 alkyl; M is sodium or potassium.

4. The application according to claim 1, in which the functional silane is preferably silane with boiling point higher than 250°C, which is one of the following or a mixture of several from the following: N- ( -2 -aminoethyl) (3 -aminopropyl) trimethoxy silane, N- ( -2 -aminoethyl) (3 -aminopropyl) triethoxy silane,

N- (-2 -aminoethyl) (3 -aminopropyl) methyl dimethoxy silane,

N- (- 2-aminoethyl) (3 -aminopropyl) methyl diethoxy silane,

(3 -aminopropyl) trimethoxy silane, (3 -aminopropyl) triethoxy silane, (3 -aminopropyl) methyl dimethoxy silane, (3 -aminopropyl) methyl diethoxy silane, (3 -ureidopropyl) trimethoxy silane,

(3 -ureidopropyl) triethoxy silane, (3 -ureidopropyl) methyldimethoxy silane, (3 -ureidopropyl) methyldiethoxy silane.

5. The application according to claim 1, in the composite, the alkylsilanol metal salt is 1-99%, based on total weight of the water-based pH regulator (w/w) .

6. The application according to claim 1, in the composite, the functional silane is 0.1-99%, based on total weight of the water-based pH regulator (w/w) .

7. The application according to claim 1, the composite also contains 0.1-10% potassium hydroxide or sodium hydroxide.

8. The application according to claim 1, the silicone composite is 0.05-1 % of the water-based architectural coating (w/w) .

9. The application according to claim 1, the water-based architectural coatings include vinyl acetate-ethylene coating system, styrene acrylic coating system, pure acrylic coating system, silicone-acrylic coating system and vinyl acetate-acrylic coating system .