Aqueous coating composition

Patent metadata

Field	Value
Publication number	US-12534635-B2
Application number	US-202017631777-A
Country	US
Kind code	B2
Filing date	Jun 8, 2020
Priority date	Aug 2, 2019
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

The present invention provides an aqueous coating composition which is capable of forming a coating film that has excellent cissing resistance and water resistance. An aqueous coating composition which contains (A) at least one hydroxyl group-containing resin that is selected from among (A1) hydroxyl group-containing acrylic resins and (A2) hydroxyl group-containing polyester resins, (B) an oligomer and (C) an alkyl etherified melamine resin, wherein: the oligomer (B) has a number average molecular weight within the range of from 200 to 800 and a solubility parameter within the range of from 10.0 to 13.5; and the molar ratio of methyl groups to butyl groups in the alkyl etherified melamine resin (C), namely (methyl group)/(butyl group) molar ratio is from 50/50 to 0/100.

First claim

The invention claimed is:

1 . A method for forming a multilayer coating film, comprising applying an aqueous coating composition onto an article to be coated comprising an exterior plate of automobile body or an automobile part to form a base coating film, and applying a clear coating composition (Z) on the base coating film to form a clear coating film, the aqueous coating composition comprising (A) one or more hydroxyl group-containing resins selected from the group consisting of (A1) hydroxyl group-containing acrylic resins and (A2) hydroxyl group-containing polyester resins, (B) an oligomer and (C) an alkyl etherified melamine resin, wherein
the oligomer (B) has a number-average molecular weight in the range of 200 to 800 and a solubility parameter in the range of 10.0 to 13.5, and
the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) is 50/50 to 0/100 as the (methyl group)/(butyl group) molar ratio.

2 . The method of claim 1 , wherein the number-average molecular weight of the oligomer (B) in the aqueous coating composition is in the range of 200 to 500.

3 . The method of claim 1 , wherein the solubility parameter of the oligomer (B) in the aqueous coating composition is in the range of 10.7 to 13.5.

4 . The method of claim 2 , wherein the solubility parameter of the oligomer (B) in the aqueous coating composition is in the range of 10.7 to 13.5.

5 . The method of claim 1 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

6 . The method of claim 2 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

7 . The method of claim 3 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

8 . The method of claim 4 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

9 . The method according to claim 1 , wherein the article to be coated by the aqueous coating composition comprises an undercoat coating film and/or an intermediate coating film.

10 . The method according to claim 1 , comprising coating the aqueous coating composition the article to be coated by air spray coating, airless spray coating, rotary atomizing coating, or curtain coating.

11 . A method for forming a multilayer coating film, comprising applying an aqueous coating composition onto an article to be coated to form a base coating film by air spray coating, airless spray coating, rotary atomizing coating, or curtain coating, and applying a clear coating composition (Z) on the base coating film to form a clear coating film, the aqueous coating composition comprising (A) one or more hydroxyl group-containing resins selected from the group consisting of (A1) hydroxyl group-containing acrylic resins and (A2) hydroxyl group-containing polyester resins, (B) an oligomer and (C) an alkyl etherified melamine resin, wherein
the oligomer (B) has a number-average molecular weight in the range of 200 to 800 and a solubility parameter in the range of 10.0 to 13.5, and the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) is 50/50 to 0/100 as the (methyl group)/(butyl group) molar ratio.

12 . The method of claim 11 , wherein the number-average molecular weight of the oligomer (B) in the aqueous coating composition is in the range of 200 to 500.

13 . The method of claim 11 , wherein the solubility parameter of the oligomer (B) in the aqueous coating composition is in the range of 10.7 to 13.5.

14 . The method of claim 12 , wherein the solubility parameter of the oligomer (B) in the aqueous coating composition is in the range of 10.7 to 13.5.

15 . The method of claim 11 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

16 . The method of claim 12 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

17 . The method of claim 13 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

18 . The method of claim 14 , wherein the molar ratio of methyl groups and butyl groups in the alkyl etherified melamine resin (C) in the aqueous coating composition is 30/70 to 0/100 as the (methyl group)/(butyl group) molar ratio.

19 . The method according to claim 11 , wherein the article to be coated by the aqueous coating composition comprises an undercoat coating film and/or an intermediate coating film.

Assignees

• Kansai Paint Co Ltd

Inventors

• Kubo Yoshitaka
• Mizutani Yusuke
• Inagaki Takuya
• Yokota Gen

Classifications

• C09D167/04

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C09D167/06 takes precedence) · CPC title

• C09D161/28

  with melamine · CPC title

• C09D5/08

  Anti-corrosive paints · CPC title

• C09D133/08 Primary

  Homopolymers or copolymers of acrylic acid esters · CPC title

• B05D2451/00

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