Hydroxyl-Functional Inherent Matting Waterborne Polyurethanes and High Performance Inherent Matting Coating Composed by the Same

Abstract

The disclosure relates to a method for preparing a hydroxyl-functional inherent matting waterborne polyurethane and a high-performance inherent matting coating made of the same. The inherent matting waterborne polyurethane includes the following components in parts by weight: a polymer polyol 15-25 parts; an isocyanate monomer 5-15 parts; 2,2-dimethylol propionic acid or 2,2-dimethylol butyric acid 0.2-0.8 parts; a pH regulator 0.1-0.7 parts; a hydroxyalkyl ethylenediamine chain extender 0.5-3.0 parts; a dialkyl alcohol amine blocking agent 0.1-4.0 parts; a diaminosulphonate chain extender 0.2-1.5 parts; a catalyst 0.01-0.05 parts; an organic solvent 2-10 parts; deionized water 50-80 parts; a thickener 0.1-3 parts. In the post-chain extension stage of the waterborne polyurethane, through hydroxyalkyl ethylene diamine chain extension and dialkyl alcohol amine blocking, hydroxyl groups are introduced into the polymer molecular chain.

Claims

1. A hydroxyl-functional inherent matting waterborne polyurethane, comprising the following components: 15-25 parts by weight of a polymer polyol; 5-15 parts by weight of an isocyanate monomer; 0.2-0.8 parts by weight of 2,2-dimethylol propionic acid or 2,2-dimethylol butyric acid; 0.1-0.7 parts by weight of a pH regulator; 0.5-3.0 parts by weight of a hydroxyalkyl ethylenediamine chain extender; 0.1-4.0 parts by weight of a dialkyl alcohol amine blocking agent; 0.2-1.5 parts by weight of a diaminosulphonate chain extender; 0.01-0.05 parts by weight of a catalyst; 2-10 parts by weight of an organic solvent; 50-80 parts by weight of deionized water; 0.1-3 parts by weight of a thickener; wherein, the polyurethane has a hydroxyl content of 0.5-2.5%, based on dry solids; the method for preparing the waterborne polyurethane includes the following steps: (a) adding the polymer polyol, isocyanate monomer, 2,2-dimethylol propionic acid or 2,2-dimethylol butyric acid, catalyst, and organic solvent to a reactor according to the above formula amount and reacting at 50-90° C. until the NCO content reaches or is less than the theoretical value, in which the isocyanate monomer is excessive; (b) cooling the above polymer to 20-40° C., adding the formula amount of the pH regulator such as triethylamine or N-methylmorpholine, and then dispersing the above reactants into the formula amount of deionized water at a high speed; (c) adding the formula amount of the hydroxyalkyl ethylenediamine chain extender, and reacting at 10-50° C. for 5-8 min; (d) adding the formula amount of the diaminosulphonate chain extender, and reacting at 10-50° C. for 5-8 min; (e) adding the formula amount of the dialkyl alcohol amine blocking agent, and reacting at 10-50° C. for another 30-60 min, to obtain a waterborne polyurethane; (f) thickening the waterborne polyurethane with a thickener, with the proviso that before the thickening, if the organic solvent added in step (a) has a high boiling point such as N-methyl-pyrrolidone, the solvent does not require to be separated; if the solvent added in step (a) is acetone or butanone, the solvent needs to be separated under reduced pressure.

2. The waterborne polyurethane according to claim 1, wherein the polymer polyol is one of conventional polyester polyol, polytetrahydrofuran ether polyol (PTMG), ethylene oxide polyether polyol (PEG), propylene oxide polyether polyol (PPG), polycaprolactone polyol (PCL), polycarbonate polyol (PCD) and polyacrylate polyol (PA), or a mixture of several kinds thereof; the molecular weight thereof ranges from 500 to 3000, and functionality thereof ranges from 2 to 3.

3. The waterborne polyurethane according to claim 1, wherein the isocyanate monomer is one of isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H MDI), tetramethylxylylene diisocyanate (TMXDI), xylylene diisocyanate (XDI), and 2,4- and/or 2,6-toluene diisocyanate (TDI), or a mixture of several kinds thereof.

4. The waterborne polyurethane according to claim 1, wherein the hydroxyalkyl ethylenediamine chain extender is one of hydroxyethyl ethylenediamine, N,N-dihydroxyethyl ethylenediamine, hydroxypropyl ethylenediamine, and (1,2-ethanediyldiimino)bis-1-butanol, or a mixture of several kinds thereof.

5. The waterborne polyurethane according to claim 1, wherein the dialkyl alcohol amine blocking agent is one of diethanolamine, diisopropanolamine and dibutanolamine, or a mixture of several kinds thereof.

6. The waterborne polyurethane according to claim 1, wherein the diaminosulphonate chain extender is one of sodium 2-[(2-aminoethyl)amino]ethanesulfonate and/or sodium 3-[(2-aminoethyl)amino]propanesulfonate.

7. The waterborne polyurethane of claim 1, wherein the organic solvent is one of N-methylpyrrolidone, N-ethylpyrrolidone, dimethylacetamide, dimethylformamide, acetone and ketone, or a mixture of several kinds thereof.

8. The waterborne polyurethane according to claim 1, wherein the thickener is one of alkali-swelling polyacrylic acid and associative hydrophobically modified polyurethane, or a mixture of several kinds thereof.

9. A method for preparing a two-pack or one-pack inherent matting waterborne coatings by using the hydroxyl-functional inherent matting waterborne polyurethane according to claim 1, comprising the following steps: adding 5-20% by weight of a water-dispersed polyisocyanate crosslinker into the hydroxyl-functional inherent matting waterborne polyurethane, to obtain a two-pack coating, which may be cured at room temperature; adding 5-18% by weight of an amino resin crosslinker into the hydroxyl-functional inherent matting waterborne polyurethane, to obtain a one-pack coating, which may be cured after being baked at 120-140° C. for 20 min; wherein paintcoats prepared by above coatings exhibit low gloss, and excellent water-resistance and solvent resistance, and have a gloss of less than 1.0 at an angle of 60 degrees; they can be widely used in various substrates such as leather, fabric, wood, metal, cement, and plastic.

Description

DESCRIPTION

Example 1

[0024] The preparation method was provided as follows: 12.1 parts by weight of polycarbonate (molecular weight: 2000), 12.1 parts by weight of polytetrahydrofuran ether diol (molecular weight: 2000), 0.45 parts by weight of 2,2-dimethylol propionic acid, and 7.6 parts by weight of isophorone diisocyanate, 4.4 parts by weight of acetone, and 0.01 parts by weight of organic bismuth catalyst were added to a reactor and reacted at 60-70° C. for 3 hours; the resulting polymer was cooled to 20-40° C.; 0.33 parts by weight of pH regulator triethylamine was added and stirred evenly; the resulting mixture was dispersed into 64.8 parts by weight of deionized water at a high speed; 1.4 parts by weight of hydroxyethyl ethylenediamine was added and reacted for 5-8 min without heating, and then 0.77 parts by weight of sodium 2-[(2-aminoethyl)amino]ethanesulfonate with 50% content was added and reacted for 5-8 min without heating; finally, 0.43 parts by weight of diethanolamine was added and reacted for 30 min without heating to obtain a waterborne polyurethane. Under heating and negative pressure conditions, acetone was removed. The waterborne polyurethane was thickened with alkali-swelling polyacrylic acid thickener to a viscosity of 1000-2000 mPa.Math.s.

[0025] The resulting waterborne polyurethane product has a solid content of 34.8% and a hydroxyl content of 1.06% (calculated by dry solids).

Example 2

[0026] The preparation method was provided as follows: 9.9 parts by weight of polycarbonate (molecular weight: 1000), 9.9 parts by weight of polyphthalic anhydride-neopentyl glycol diol (molecular weight: 1000), 0.53 parts by weight of 2,2-dimethylol propylene acid, 11.1 parts by weight of isophorone diisocyanate, 5.5 parts by weight of acetone, and 0.01 parts by weight of organic bismuth catalyst were added to a reactor and reacted at 60-70° C. for 3 hours; the resulting polymer was cooled to 20-40° C.; 0.4 parts by weight of pH regulator triethylamine was added and stirred evenly; the resulting mixture was dispersed into 64.5 parts by weight of deionized water at a high speed; 1.94 parts by weight of hydroxyethyl ethylenediamine was added and reacted for 5-8 min without heating, and then 1.07 parts by weight of sodium 2-[(2-aminoethyl)amino]ethanesulfonate with 50% content was added and reacted for 5-8 min without heating; finally, 0.69 parts by weight of diethanolamine was added and reacted for 30 min without heating to obtain a waterborne polyurethane. Under heating and negative pressure conditions, acetone was removed. The waterborne polyurethane was thickened with alkali-swelling polyacrylic acid thickener to a viscosity of 1000-2000 mPa.Math.s.

[0027] The resulting waterborne polyurethane product has a solid content of 35% and a hydroxyl content of 1.54% (calculated by dry solids).

Example 3

[0028] The preparation method was provided as follows: 9.5 parts by weight of polycarbonate (molecular weight: 1000), 9.5 parts by weight of polyphthalic anhydride-neopentyl glycol diol (molecular weight: 1000), 0.5 parts by weight of 2,2-dimethylol propylene acid, 5.0 parts by weight of dicyclohexylmethane diisocyanate, 6.5 parts by weight of isophorone diisocyanate, 8.8 parts by weight of acetone, and 0.01 parts by weight of organic bismuth catalyst were added to a reactor and reacted at 60-70° C. for 3 hours; the resulting polymer was cooled to 20-40° C.; 0.38 parts by weight of pH regulator triethylamine was added and stirred evenly; the resulting mixture was dispersed into 64.5 parts by weight of deionized water at a high speed; 1.27 parts by weight of hydroxyethyl ethylenediamine was added and reacted for 5-8 min without heating, and then 1.03 parts by weight of sodium 2-[(2-aminoethyl)amino]ethanesulfonate with 50% content was added and reacted for 5-8 min without heating; finally, 1.86 parts by weight of diethanolamine was added and reacted for 30 min without heating to obtain a waterborne polyurethane. Under heating and negative pressure conditions, acetone was removed. The waterborne polyurethane was thickened with alkali-swelling polyacrylic acid thickener to a viscosity of 1000-2000 mPa.Math.s.

[0029] The resulting waterborne polyurethane product has a solid content of 35.0% and a hydroxyl content of 2.31% (calculated by dry solids).

Example

[0030] The gloss was measured by using a gloss tester conforming to ISO2813, ASTMD1455, GB9754, GB8807 and other standards and measuring the gloss of the coating film at an angle of 60°.

[0031] The water resistance was measured according to GB/T1733-1993 by paint film water tolerance assay method.

[0032] Solvent resistance was measured according to GB/T23989-2009 standard by wiping with ethanol and butanone.

[0033] 100 parts by weight of the waterborne polyurethanes were sampled to Example 1, Example 2 and Example 3, then 5, 10, and 15 parts by weight of water-dispersible polyisocyanate crosslinker (with NCO content of 20%) were each added into the waterborne polyurethanes as sampled, and stirred evenly to prepare two-pack coatings; the coatings were coated, cured and maintained at room temperature for 7 days to obtain a coating film, and the films were then subjected to the above measurement.

[0034] 100 parts by weight of the waterborne polyurethanes were sampled to Example 1, Example 2 and Example 3, then 6, 9 and 14 parts by weight of amino resin crosslinker (such as CYMEL325) were each added into the waterborne polyurethanes as sampled, and stirred evenly to prepare one-pack coatings; the coatings were coated, and baked at 120-140° C. for 20 min to cure so as to obtain a coating film, the films were then subjected to the above measurement.

[0035] The test results are as follows:

TABLE-US-00001 TABLE 1 Test results of the Examples in which water- dispersed polyisocyanate crosslinker is added Example1 Example2 Example3 Water resistance Normal for 24 Normal for 72 Normal for 72 hours hours hours Ethanol-tolerance 10 times 20 times 50 times Butanone- 10 times 20 times 50 times tolerance gloss 0.8 1.2 1.8

TABLE-US-00002 TABLE 2 Test results of the Examples in which amino resin crosslinker is added Example1 Example2 Example3 Water resistance Normal for 72 Normal for 72 Normal for 72 hours hours hours Ethanol-tolerance 50 times 100 times 200 times Butanone- 50 times 100 times 200 times tolerance gloss 0.9 1.5 2.0