Low VOC, heat-curable, one-component and two-component coating compositions based on organic polyisocyanates

• US 5,370,908 A
• Filed: 05/24/1993
• Issued: 12/06/1994
• Est. Priority Date: 05/24/1993
• Status: Expired due to Fees

• Current Assignee: Bayer Corporation (Bayer AG)
• Original Assignee: OLIN Corporation
• Inventors: O'Connor, James M., Chandalia, Kiran B., Malofsky, Adam G., Stuber, Fred A.
• Primary Examiner(s): LUSIGNAN, MICHAEL R
• Application Number:
  US08/065,009
• Time in Patent Office: 561 Days
• Field of Search: 427/385.5, 528/45, 528/67, 528/73, 428/422.8, 428/423.1
• US Class Current: 427/385.5
• CPC Class Codes: C08G 18/022 the polymeric products containing isocyanurate groups
• CPC Class Codes: C08G 18/092 oligomerisation to isocyanurate groups
• CPC Class Codes: C08G 18/163 covered by C08G18/18 and C08G18/22
• CPC Class Codes: C08G 18/168 Organic compounds
• CPC Class Codes: C08G 18/283 Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
• CPC Class Codes: C09D 175/00 Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
• CPC Class Codes: C09D 175/04 Polyurethanes
• CPC Class Codes: Y10T 428/31547 Of polyisocyanurate
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]

Abstract

The present invention relates to a process for coating a substrate which comprises (a) contacting said substrate with a low volatility organic (so-called "low VOC") coating composition having a viscosity as measured by ZAHN cup 2 of less than about 200 seconds and consisting essentially of at least one polyisocyanate, a solvent in an amount of between 0% and 45% by weight based upon the amount of said polyisocyanate in said composition, and an trimerization catalyst, said composition being essentially free of any volatile mono- and di-isocyanates, to form a coating on said substrate, and (b) heating said coating to a curing temperature of between 120° F. and 350° F. for a curing time of between about ten minutes and about six hours in order to cure said coating by trimerizing at least some of the isocyanate groups of the polyisocyanate to provide a heat-cured coating on said substrate. Also claimed is the coating composition itself.

Claims

1. A process for coating a substrate which comprises:

(a) contacting said substrate with a low volatile organic compounds-containing coating composition having a viscosity as measured by ZAHN cup 2 of less than about 200 seconds and consisting essentially of at least one polyisocyanate having an average functionality of between 2.5 and 6 and containing at least one moiety selected from the group consisting of biuret, isocyanurate, uretidione, allophanate, urethane, and combinations thereof, a solvent in an amount of between 0% and 45% by weight based upon the amount of said polyisocyanate in said composition, and a trimerization catalyst, said composition being essentially free of any volatile mono- and di-isocyanates, to form a coating on said substrate, and

(b) heating said coating to a curing temperature of between 120°

F. and about 350°

F. for a curing time of between about ten minutes and about six hours in order to cure said coating by trimerizing at least some isocyanate groups of said polyisocyanate to provide a heat-cured coating on said substrate.

2. The process of claim 1 wherein said coating composition is solvent-free.

3. The process of claim 1 wherein said solvent is selected from the group consisting of toluene, xylene, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methylamyl ketone, ethoxyethylacetate, ethylethoxy propionate, an aromatic hydrocarbon mixture having a boiling point of 152°

-174°

C. and combinations thereof.

4. The process of claim 1 wherein said polyisocyanate is selected from the group consisting of aliphatic or cycloaliphatic polyisocyanates, and combinations thereof.

5. The process of claim 4 wherein said polyisocyanate is an aliphatic polyisocyanate prepared from hexamethylene diisocyanate.

6. The process of claim 1 wherein said polyisocyanate is selected from the group consisting of tris-(isocyanatohexyl)-biuret, tris-(isocyanatohexyl)isocyanurate, cyclodimerized hexamethylene diisocyanate and combinations thereof.