Vapor permeation curable coatings comprising polymercaptan resins and multi-isocyanate curing agents

• US 4,753,825 A
• Filed: 09/09/1986
• Issued: 06/28/1988
• Est. Priority Date: 05/31/1985
• Status: Expired due to Term

• Current Assignee: Sherwin-Williams Company
• Original Assignee: Ashland Oil, Inc. (Ashland Global Holdings, Inc.)
• Inventors: Linden, Gary L., Blakley, Brent A.
• Primary Examiner(s): Bell, Janyce A.
• Application Number:
  US06/905,700
• Time in Patent Office: 658 Days
• Field of Search: 427/30, 427/340, 427/426, 427/255.6, 427/248.1, 528/73, 528/65, 528/85, 428/423.1
• US Class Current: 427/340
• CPC Class Codes: C08G 18/1891 in vaporous state
• CPC Class Codes: C08G 18/3876 containing mercapto groups
• CPC Class Codes: C08G 18/40 High-molecular-weight compounds C08G18/2805 takes precedence
• CPC Class Codes: C08G 18/4676 containing sulfur
• CPC Class Codes: C08G 18/5072 containing sulfur

Abstract

Disclosed is a method for curing a film of a coating composition under vapor permeation curable conditions. Such method comprises exposing a coating composition to a vaporous tertiary amine catalyst. The coating composition can be in the form of an atomizate which is concurrently generated and mixed with a vaporous tertiary amine catalyst followed by application to a substrate, or can be an applied film of the coating composition which is exposed to the vaporous tertiary amine catalyst. The coating composition comprises a polymercapto-compound and a multi-isocyanate curing agent. The coating composition can be formulated to contain very high solids content (e.g. in excess of 70% and on up to 100% non-volatile solids).

Claims

1. Method for curing a film of a coating composition which comprises exposing said coating composition as an atomizate which then is applied to a substrate or as an applied film on a substrate to a vaporous tertiary amine catalyst, said coating composition comprising a polymercapto compound and a polyisocyanate curing agent.

2. The method of claim 1 wherein said coating composition is dispersed in a fugitive organic solvent.

3. The method of claim 1 wherein said polymercapto compound is a monomer, oligomer, or polymer.

4. The method of claim 1 wherein the molar ratio of mercapto groups to isocyanate groups in said coating composition is between about 1:

1 and 1;

2.

5. The method of claim 1 wherein said coating composition also contains a particulate filler.

6. The method of claim 1 wherein said polymercapto compound is selected from or the mercapto groups thereon are derived from the group consisting of 1,4-butane dithiol, 2,3-dimercapto propanol, toluene-3,4-dithiol, alpha,alpha'"'"'-dimercapto-p-xylene thiosalicyclic acid, mercapto acetic acid, 2-mercapto ethanol, monododecane dithiol, didodecane dithiol, dithiol phenol, dipara-chlorothiophenol, dimercapto benzothiazole, 3,4-dimercapto toluene, allyl mercaptan, 1,6 hexane dithiol, benzyl mercaptan, 1-octane thiol, p-thiocresol, 2,3,5,6-tetrafluorothiophenol, cyclohexyl mercaptan, methylthioglycolate, mercapto pyridines, dithioerythritol, 6-ethoxy-2-mercaptobenzothiazol, and mixtures thereof.

7. The method of claim 1 wherein the coating composition is cured by exposure of an applied film thereof to a vaporous tertiary amine catalyst.

8. The method of claim 1 wherein an atomizate of said coating composition concurrently generated with a vaporous tertiary amine catalyst are admixed, said mixture applied to a substrate, and said coating composition cured.

9. The method of claim 1 wherein said curing agent is selected from an aliphatic polyisocyanate curing agent, an aromatic polyisocyanate curing agent, and mixtures thereof.

10. In a method for curing the film of coating composition which comprises exposing said coating composition as an atomizate which then is applied to a substrate or as an applied film on a substrate to a vaporous tertiary amine catalyst, said coating composition comprising a polyol and a polyisocyanate curing agent, the improvement which comprises said coating composition being cured in the presence of a thio-urethane compound formed by the reaction of a mercapto compound and an isocyanate compound.

11. The method of claim 10 wherein said coating composition additionally comprises a mercapto compound when forms said thio-urethane compound in situ during the curing of said coating composition.

12. The method of claim 10 wherein said thio-urethane compound is pre-formed and added to said coating composition.

13. The method of claim 10 wherein said thio-urethane compound is represented by one of the following structures:

##STR3## where R₁ and R₂ each is a monovalent organic radical.

14. The method of claim 13 wherein R₁ and R₂ each is an alkyl or aryl group.

15. The method of claim 11 wherein said mercapto compound is a monomercapto compound, a polymercapto compound, or mixtures thereof.

16. The method of claim 10 wherein said polyisocyanate curing agent is selected from an aromatic polyisocyanate, an aliphatic polyisocyanate, and mixtures thereof;

and said polyol is selected from an aromatic polyol, or mixtures of an aliphatic polyol and an aromatic polyol.