METHOD OF FORMING A COATING FILM

• US 20100203259A1
• Filed: 01/21/2010
• Published: 08/12/2010
• Est. Priority Date: 02/06/2009
• Status: Abandoned Application

• Current Assignee: Nippon Bee Chemical Co. Ltd.
• Original Assignee: Nippon Bee Chemical Co. Ltd.
• Inventors: SAITOU, Yoshihiko, KAMITANI, Akira
• Application Number:
  US12/691,107
• Publication Number:
  US 20100203259A1
• Time in Patent Office: Days
• US Class Current: 427/532
• 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 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08J 2323/12 Polypropene
• CPC Class Codes: C08J 2429/14 Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• 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: C08J 7/046 Forming abrasion-resistant coatings; Forming surface-hardening coatings
• CPC Class Codes: C08J 7/18 using wave energy or particle radiation
• CPC Class Codes: C09D 133/066 containing -OH groups
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

A method for forming a coating film able to reduce curing time, reduce the size of coating equipment and reduce the amount of CO₂, without deterioration in such properties as water resistance and weather resistance. The method for forming the coating film includes the steps of (1) applying a base coating composition, (2) applying a top coating composition on the base coat layer obtained in said step (1), (3) irradiating energy line on the uncured coating film obtained in step (2), and (4) bake curing after step (3). The top coating composition includes a hydroxyl group-containing resin (A), an activation energy line-curable compound containing an unsaturated bond (B), and a polyisocyanate compound (c), with a compounding proportion of (A), (B) and (C) based on weight satisfying the ratio: ((A)+(C))/(B)=90/10 to 50/50.

Claims

1. A method for forming a coating film comprising a step (1) of applying a base coating composition, a step (2) of applying a top coating composition on the base coat layer obtained in said step (1), a step (3) of irradiating energy line on the uncured coating film obtained in said step (2), and a step (4) of bake curing after said step (3),

wherein said top coating composition comprises a hydroxyl group-containing resin (A), an activation energy line-curable compound containing an unsaturated bond (B), and a polyisocyanate compound (c),

said hydroxyl group-containing resin (A) has glass-transition temperature (Tg) of −

20 to 50°

C., weight average molecular weight of 10000 to 30000, and hydroxyl group value of 80 to 230 (KOHmg/g), and a ratio between primary hydroxyl group and secondary hydroxyl group based on hydroxyl group value satisfies the following formula,

Primary hydroxyl group/secondary hydroxyl group=30/70 to 80/20,

said polyisocyanate compound (c) has an average isocyanate group number of 2.5 to 3.4,

an equivalent ratio between hydroxyl group in said hydroxyl group-containing resin (A) and isocyanate group in said polyisocyanate compound (C) (NCO/OH) is 1.2 to 3.0, and

a compounding proportion of (A), (B) and (C) based on weight ratio satisfies the following formula,

((A)+(C))/(B)=90/10 to 50/50.

2. The method for forming a coating film according to claim 1, wherein the step (4) is conducted at 70 to 100°

C.

3. The method for forming a coating film according to claim 1, wherein the top coating composition has nonvolatile content of 45 to 65 weight %.

4. The method for forming a coating film according to claim 2, wherein the top coating composition has nonvolatile content of 45 to 65 weight %.