Coating composition

Patent metadata

Field	Value
Publication number	US-11168231-B2
Application number	US-201917056083-A
Country	US
Kind code	B2
Filing date	Jun 12, 2019
Priority date	Jun 15, 2018
Publication date	Nov 9, 2021
Grant date	Nov 9, 2021

Abstract

The present invention relates to a coating composition, a coating system comprising the coating composition, a coating method and application of the coating system, and a product coated with the coating system. The coating composition comprises: (A) at least one aqueous polyurethane dispersion and/or one aqueous polyacrylate dispersion, wherein the aqueous polyurethane dispersion comprises at least one polyurethane polymer (a), wherein the polyurethane polymer (a) is obtained by a reaction comprising at least one polyurethane prepolymer (a1) and at least one isocyanate-reactive component (a2), wherein the polyurethane prepolymer (a1) is obtained by a reaction comprising the following components: (a1-1) at least one polyisocyanate having an isocyanate functionality of no less than 2, and (a1-2) at least one polyfunctional polyether polyol having a hydroxyl functionality of no less than 3, wherein the polyfunctional polyether polyol has an amount of 1 wt % to 20 wt %, based on the amount of the components for preparing the polyurethane prepolymer being 100 wt %, and (B) at least one crosslinking agent.

First claim

The invention claimed is:

1. A coating composition, comprising:
(A) at least one aqueous polyurethane dispersion and optionally at least one aqueous polyacrylate dispersion, wherein the aqueous polyurethane dispersion comprises at least one polyurethane polymer (a), wherein the polyurethane polymer (a) is obtained by a reaction comprising at least one polyurethane prepolymer (a1) and at least one isocyanate-reactive component (a2), wherein the polyurethane prepolymer (a1) is obtained by a reaction comprising the following components:
(a1-1) at least one polyisocyanate having an isocyanate functionality of no less than 2, the at least one polyisocyanate comprising a cycloaliphatic polyisocyanate having at least two aliphatic rings, wherein the cycloaliphatic polyisocyanate is present in an amount of from 25 wt % to 90 wt %, based on a total amount of the polyisocyanate (a1-1) being 100 wt %,
(a1-2) at least one polyfunctional polyether polyol having a hydroxyl functionality of no less than 3, wherein the polyfunctional polyether polyol is present in an amount of from 1 wt % to 20 wt %, based on a total amount of the components for preparing the polyurethane prepolymer being 100 wt %, and
(a1-3) optionally a polymer polyol different from the polyfunctional polyether polyol having a hydroxyl functionality of no less than 3;

(B) at least one crosslinking agent; and
(C) optionally an additive,
optionally wherein the isocyanate-reactive component (a2) comprises anionic hydrophilic agents and/or potentially anionic hydrophilic agents.

2. The coating composition according to claim 1 , wherein the at least one polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3 is obtained by a reaction comprising at least one ethylene oxide and at least one initiator,
optionally wherein the at least one polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3 has a structure according to formula I:

wherein
m is 0-50,
n is 1-50,
m′ is no less than 3,
X is one or more of the following: 1,3-propylidene, 1,2-isopropylidene (—CH(CH 3 )CH 2 —), 2,2-propylidene (—C(CH 3 ) 2 —), 1,1-butylidene, 1,2-butylidene, 2,2-butylidene, 1,3-butylidene, 1,4-butylidene, 1,2-pentylidene, 1,3-pentylidene, 1,4-pentylidene, 1,5-pentylidene, 1,6-hexylidene, 1,7-heptylidene, 1,8-octylidene, 1,9-nonylidene, 1,10-decylidene, 1,11-undecylidene, 1,12-dodecylidene, 1,2-cyclopentylidene, 1,2-cyclohexylidene, 1,2-cycloheptylidene, 1,2-cyclooctylidene, 1,2-styrylidene, 1,2-methylstyrylidene, and 1,2-pinanylidene, and
R is C y H z , wherein y is equal to the number of carbon atoms of the initiator, and z is an integer that renders formula I established, and
optionally wherein the initiator comprises monosaccharides, oligosaccharides, polysaccharides, pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylolethane, trimethylolpropane, sorbitol, a cyclic polyol, an aromatic hydroxy compound, a polyamine, a compound having carboxyl groups, a compound having hydroxyl and carboxyl groups, or a combination thereof.

3. The coating composition according to claim 1 , wherein the at least one polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3 has a number-average molecular weight of 500 g/mol to 12,000 g/mol, or
wherein the at least one polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3 is present in an amount of from 1 wt % to 15 wt %, based on the total amount of the components for preparing the polyurethane prepolymer being 100 wt %,
or both.

4. The coating composition according to claim 1 , wherein the crosslinking agent (B) is an aliphatic and/or aromatic isocyanate derivative containing a reactive group, wherein the reactive group is capable of reacting with a group containing an active hydrogen, and the group containing the active hydrogen comprises a hydroxyl group, a carboxyl group, a mercapto group, an amino group, or a combination thereof,
optionally wherein the reactive group is present in an amount of from 0.1 wt % to 2 wt %, based on a total amount of the coating composition being 100 wt %, and
optionally wherein the crosslinking agent (B) is hydrophilically modified.

5. The coating composition according to claim 1 , wherein the crosslinking agent (B) comprises a blocked aliphatic polyisocyanate, a non-blocked aliphatic polyisocyanate, a carbodiimide, a melamine-type crosslinking agent, an aziridine-type crosslinking agent, a polyepoxy crosslinking agent, or a combination thereof.

6. The coating composition according to claim 1 , wherein the polyisocyanate (a1-1) comprises an aliphatic polyisocyanate and/or wherein the cycloaliphatic polyisocyanate is dicyclohexylmethane diisocyanate.

7. The coating composition according to claim 1 , wherein the polymer polyol (a1-3) comprises polycarbonate polyols, polyester polyols, low-functional polyether polyols, or a combination thereof, and optionally wherein a weight ratio of the polyfunctional polyether polyol (a1-2) to the polycarbonate polyol is 1:4 to 1:10.

8. The coating composition according to claim 1 , wherein the aqueous polyurethane dispersion is present in an amount of from 50 wt % to 99 wt %, based on a total amount of the coating composition being 100 wt %.

9. A method for preparing a coating composition according to claim 1 , wherein the method comprises: mixing the aqueous polyurethane dispersion and/or the aqueous polyacrylate dispersion (A), the crosslinking agent (B) and the optional additive (C) in any desired manner.

10. The method according to claim 9 , wherein the aqueous polyurethane dispersion (A) is prepared by:
(1) reacting a mixture comprising at least one polyisocyanate (a1-1), at least one polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3, and optionally a polymer polyol (a1-3) different from the polyfunctional polyether polyol having a hydroxyl functionality of no less than 3 to obtain the polyurethane prepolymer (a1);
(2) reacting a mixture comprising at least one polyurethane prepolymer (a1) and at least one isocyanate-reactive component (a2) to obtain the polyurethane polymer (a); and
(3) introducing water before, during, or after step (2) to obtain the aqueous polyurethane dispersion (A).

11. A coated product comprising a substrate and a coating formed by:
coating the coating composition according to claim 1 on the substrate, and/or
curing the coating composition according to claim 1 on the substrate.

12. A method for producing a coated product, comprising coating a coating composition according to claim 1 on a substrate and curing it to form a coating.

13. A coating system, comprising:
a first composition, the first composition being the coating composition according to claim 1 , wherein the polymer polyol (a1-3) different from the polyfunctional polyether polyol having a hydroxyl functionality of no less than 3 comprises at least one polycarbonate polyol, and a weight ratio of the polyfunctional polyether polyol (a1-2) having a hydroxyl functionality of no less than 3 to the polycarbonate polyol is 1:4 to 1:10, wherein the first composition is used to form a first coating, and
a second composition, the second composition being the coating composition according to claim 1 , wherein the polymer polyol (a1-3) different from the polyfunctional polyether polyol having a hydroxyl functionality of no less than 3 comprises at least one polyester polyol, and a weight ratio of the polyfunctional polyether polyol (

Assignees

• Covestro Intellectual Property Gmbh & Co Kg

Inventors

• Fan Zhirong
• Li Xuedong
• Ye Huimin
• Zhai Su Juan

Classifications

• C08G18/73 Primary

  acyclic · CPC title

• C08G18/792

  formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates · CPC title

• C08G18/485

  containing mixed oxyethylene-oxypropylene or oxyethylene-higher oxyalkylene end groups · CPC title

• C08G18/0866

  the dispersing or dispersed phase being an aqueous medium · CPC title

• C08G18/6685

  with compounds of group C08G18/3225 or polyamines of C08G18/38 · CPC title