Low temperature cure coating formed via a double layer curing mechanism of a pigmented waterborne baselayer and a solventborne top layer

Patent metadata

Field	Value
Publication number	US-10113085-B2
Application number	US-201615220081-A
Country	US
Kind code	B2
Filing date	Jul 26, 2016
Priority date	Jul 26, 2016
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

Shelf-stable low temperature cure coating compositions that include a hydroxy-functional resin, a crosslinking agent, and a catalyst that does not catalyze the crosslinking reaction between hydroxy-functional resin and the crosslinking agent contained therein, but instead between a hydroxy-functional resin and a crosslinking agent contained in a different low temperature cure coating composition. In addition, low temperature cure composite coatings that include: a waterborne basecoat containing a first hydroxy-functional resin, a first crosslinking agent, a first catalyst, and an organic solvent; and a solventborne topcoat containing a second hydroxy-functional resin, a second crosslinking agent, a second catalyst, and water, where the first catalyst migrates into the topcoat from the basecoat and catalyzes the reaction between the second hydroxy-functional resin and crosslinking agent, and the second catalyst migrates into the basecoat from the topcoat and catalyzes the reaction between the first hydroxy-functional resin and crosslinking agent.

First claim

The invention claimed is:

1. A low temperature cure composite coating, comprising:
a substrate;
a first layer comprising a waterborne low temperature cure coating composition comprising
a first hydroxy-functional resin, which is a hydroxy-functional polyether-comprising polyurethane,
a first low temperature crosslinking agent, which is an aminoplast resin, and
a first catalyst, which is a metal catalyst, and
water; and

a second layer comprising a solventborne low temperature cure coating composition comprising
a second hydroxy-functional resin, which is a hydroxy-functional acrylic resin or a hydroxy-functional polyester resin;
a second low temperature crosslinking agent, which is an isocyanate resin that is optionally blocked,
a second catalyst, which is an acid catalyst, and
an organic solvent,

wherein the first layer and the second layer are adjacent to each other,
wherein the first catalyst catalyzes a crosslinking reaction between the second hydroxy-functional resin and the second low temperature crosslinking agent, and does not catalyze a crosslinking reaction between the first hydroxy-functional resin and the first low temperature crosslinking agent,
wherein the second catalyst catalyzes a crosslinking reaction between the first hydroxy-functional resin and the first low temperature crosslinking agent, and does not catalyze a crosslinking reaction between the second hydroxy-functional resin and the second low temperature crosslinking agent, and
wherein the solventborne and the waterborne low temperature cure coating compositions cure within 20 minutes at a temperature from 80-120° C.

2. The coating of claim 1 , wherein the aminoplast resin is a condensation product of formaldehyde and melamine.

3. The coating of claim 1 , wherein the aminoplast resin has formula (1):

where each R is independently selected from H and C 1 -C 4 alkyl groups, with the proviso that at least two R groups are different.

4. The coating of claim 1 , wherein the metal catalyst is an organometallic bismuth, tin, lithium, or zirconium catalyst.

5. The coating of claim 1 , wherein the metal catalyst is a dialkyl tin compound selected from the group consisting of dibutyltin oxide, dioctyl tin oxide, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dimaleate, dibutyl tin distearate, dipropyl tin dioctoate, and dioctyl tin oxide.

6. The coating of claim 1 , wherein the isocyanate resin comprises at least one diisocyanate selected from the groups consisting of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, 2,3-dimethylethylene diisocyanate, 1-methyltrimethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, 4,4-diphenylene diisocyanate, 1,5-naphthylene diisocyanate, 1,4-naphthylene diisocyanate, 1-isocyanatomethyl-3-isocyanato-3,5,5-trimethylcyclohexane, 1,3-bis(1-isocyanato-1-methylethyl)benzene, bis(4-isocyanatocyclohexyl)methane, bis(4-isocyanatophenyl)methane, 4,4′-diisocyanatodiphenyl ether, and 2,3-bis(8-isocyanatooctyl)-4-octyl-5-hexylcyclohexane.

7. The coating of claim 6 , wherein the diisocyanate is at least one selected from the group consisting of hexamethylene diisocyanate, 1-isocyanatomethyl-3-isocyanato-3,5,5-trimethylcyclohexane, and 1,3-bis(1-isocyanato-1-methylethyl)benzene.

8. The coating of claim 1 , wherein the acid catalyst is an organic sulfonic acid selected from the group consisting of para-toluenesulfonic acid, methanesulfonic acid, dodecylbenzene sulfonic acid, dinonylnaphthalene disulfonic acid, and mixtures thereof.

9. The coating of claim 1 , wherein the acid catalyst is a carboxylic acid selected from the group consisting of dimethylolpropionic acid, trimethylol acetic acid, dimethyl butyric acid, dimethyl pentanoic acid, butyric acid, hexanoic acid, heptanoic acid, octanoic acid, pelargonic acid, decanoic acid, 2-ethylhexanoic acid, lauric acid, and mixtures thereof.

10. The coating of claim 1 , wherein the waterborne low temperature cure coating composition has a pot life of at least 30 days.

11. The coating of claim 1 , wherein the solventborne low temperature cure coating composition does not comprise water.

12. The coating of claim 1 , wherein the waterborne low temperature cure coating composition further comprises a pigment or colorant.

13. The coating of claim 1 , wherein the substrate comprises at least one thermoplastic material selected from the group consisting of a polyolefin, a polyamide, a polyurethane, a polyester, a polycarbonate, an acrylonitrile-butadiene-styrene (ABS) copolymer, an EPDM rubber, an acrylic polymer, and a vinyl polymer.

14. The coating of claim 1 , wherein the waterborne low temperature cure coating composition comprises, based on a total weight of resin solids in the composition:
from 35 to 65 percent by weight of the first hydroxy-functional resin;
from 15 to 65 percent by weight of the first low temperature crosslinking agent; and
from 0.05 to 7.5 percent by weight of the first catalyst.

15. The coating of claim 14 , wherein the waterborne low temperature cure coating composition further comprises the second catalyst, wherein the content of the second catalyst in the first low temperature cure coating composition is less than the content of the first catalyst.

16. The coating of claim 1 , wherein the solventborne low temperature cure coating composition comprises, based on a total weight of resin solids in the composition:
from 35 to 65 percent by weight of the second hydroxy-functional resin;
from 35 to 65 percent by weight of the second low temperature crosslinking agent; and
from 0.25 to 7.5 percent by weight of the second catalyst.

17. The coating of claim 16 , wherein the solventborne low temperature cure coating composition further comprises the first catalyst, wherein the content of the first catalyst in the second low temperature cure coating composition is less than the content of the second catalyst.

18. A low temperature composite coating, obtained by curing the coating of claim 1 for 20 minutes or less at a temperature from 80 to 120° C.

19. A kit, comprising:
a first one component, waterborne low temperature cure coating composition comprising
a first hydroxy-functional resin, which is a hydroxy-functional polyether-comprising polyurethane;
a first low temperature crosslinking agent, which is an aminoplast resin, and
a first catalyst, which is a metal catalyst, and
water; and

a second two component, solventborne low temperature cure coating composition comprising
a first component comprising a second hydroxy-functional resin, which is a hydroxy-functional acrylic resin or a hydroxy-functional polyester resin, and an organic solvent, and
a second component comprising a second low temperature crosslinking agent, which is an isocyanate resin that is optionally blocked, and an organic solvent,
wherein at least one of the first component and the second component further comprises a second catalyst, which is an acid catalyst,

wherein the waterborne low temperature cure coating composition does not comprise a catalyst that catalyzes a reaction between the first hydroxy-functional resin and the first low temperature crosslinking agent, and t

Assignees

• Basf Coatings Gmbh

Inventors

• December Timothy S
• Clark Timothy
• Ozvald Adam M

Classifications

• B05D2425/02

  second layer from the top surface · CPC title

• B05D2425/01

  top layer/ last layer, i.e. first layer from the top surface · CPC title

• C09D187/005 Primary

  Block or graft polymers not provided for in groups C09D101/00 - C09D185/04 · CPC title

• C08K5/34922

  Melamine; Derivatives thereof · CPC title

• B05D2451/00

  Type of carrier, type of coating (Multilayers) · CPC title