Coating method with crosslinked coatings from two coat-one bake systems

• US 4,759,961 A
• Filed: 05/12/1987
• Issued: 07/26/1988
• Est. Priority Date: 01/10/1985
• Status: Expired due to Fees

• Current Assignee: Kansai Paint Company Limited
• Original Assignee: Kansai Paint Company Limited
• Inventors: Kato, Tadahiro, Kiyata, Hiroaki, Mitsuzi, Masaru, Iihashi, Mototaka, Fujii, Yasuhiro
• Primary Examiner(s): Page, Thurman K.
• Application Number:
  US07/048,990
• Time in Patent Office: 441 Days
• Field of Search: 427/407.1, 427/409, 427/408, 427/412.1, 427/412.3
• US Class Current: 427/407.1
• CPC Class Codes: B05D 7/26 synthetic lacquers or varnishes B05D7/08, B05D7/16 take precedence
• CPC Class Codes: C08G 18/16 Catalysts catalysts in general B01J
• CPC Class Codes: C08G 18/4263 containing carboxylic acid groups
• CPC Class Codes: C08G 18/6254 Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
• CPC Class Codes: C08G 18/633 onto polymers of compounds having carbon-to-carbon double bonds
• CPC Class Codes: C08J 2323/12 Polypropene
• CPC Class Codes: C08J 2475/04 Polyurethanes
• CPC Class Codes: C08J 2475/12 from compounds containing nitrogen and active hydrogen, the nitrogen atom not being part of an isocyanate group
• CPC Class Codes: C08J 7/042 with two or more layers, where at least one layer of a composition contains a polymer binder
• CPC Class Codes: C08J 7/0423 with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

In a method for forming coatings, comprising the steps of applying a base coating containing a coloring pigment and/or a metallic pigment to produce a base coat, applying a topcoating containing a hydroxyl group-containing resin and a polyisocyanate compound over the base coat, and curing the coats at a temperature range between room temperature to about 140° C., the method which is characterized in that the base coating contains the following as a vehicle component;

(a) a resin having hydroxyl group and carboxyl group in the molecule,

(b) a combination of the resin having hydroxyl group in the molecule and a catalyst for promoting the reaction between the hydroxyl group of the resin and the isocyanate group of the polyisocyanate compound in the topcoating or

(c) a combination of the resin having hydroxyl group and carboxyl group in the molecule and a catalyst for promoting the reaction between the hydroxyl group of the resin and the isocyanate group of the polyisocyanate compound in the topcoating.

Claims

1. In a method for forming coatings on a substrate, comprising the steps of applying to the substrate a base coating consisting essentially of (i) a coloring pigment and/or a metallic pigment and (ii) a vehicle component in a solvent to produce a base coat, appying a topcoating containing a hydroxyl group-containing resin and a polyisocyanate compound over the base coat, and curing the coats at a temperature range between room temperature and about 140°

C., the improvement wherein the vehicle component is selected from the group consisting of;

(a) a resin having a hydroxyl group and a carboxyl group in the molecule;

(b) a combination of a resin having a hydroxyl group in the molecule and a catalyst for promoting the reaction between the hydroxyl group of the resin and an isocyanate group of the polyisocyanate compound in the topcoating; and

(c) a combination of a resin having a hydroxyl group and a carboxyl group in the molecule and a catalyst for promoting the reaction between the hydroxyl group of the resin and an isocyanate group of the polyisocyanate compound in the topcoating;

wherein the resin contained in the base coating has a number-average molecular weight of about 5,000 to about 100,000 when the solvent of the base coating is an organic solvent and a number-average molecular weight of about 5,000 to about 2,000,000 when the solvent of the base coating is an aqueous solvent.

2. A method according to claim 1 wherein the base coating is an organic solvent based composition.

3. A method according to claim 1 wherein the base coating is an aqueous solvent based composition.

4. A method according to claim 2 wherein said base coating comprises a resin having a hydroxyl group in the molecule or a resin having a hydroxyl group and a carboxyl group in the molecule, and a catalyst for accelerating the reaction between the hydroxyl group in the resin and the isocyanate group of the polyisocyanate compound in the topcoat.

5. A method according to claim 1 wherein the resin having hydroxy in the molecule or the resin having a hydroxyl group and a carboxyl group in the molecule is selected from the group consisting of acrylic resins, chlorinated polyolefin-modified acrylic resins and polyester resins, each having a hydroxyl group or a hydroxyl group and a carboxyl group in the molecule.

6. A method according to claim 1 wherein the hydroxyl group-containing resin or the hydroxyl group- and carboxyl group-containing resin has a hydroxyl value of about 5 to about 200.

7. A method according to claim 6 wherein said hydroxyl value is between about 10 and about 120.

8. A method according to claim 7 wherein the hydroxyl value of the resin is between 15 and 100.

9. A method according to claim 1 wherein the base coating is an organic solvent based composition and the resin having a hydroxyl group and a carboxyl group in the molecule has an acid value of about 2 to about 30.

10. A method according to claim 1 wherein the base coating is an aqueous composition and the hydroxyl group- and carboxyl group-containing resin has an acid value of about 1 to about 200.

11. A substrate coated by the method as defined in claim 1.