Curable compositions based on polyuretidiones, polythiols and photoactivable bases and generation of isocyanates from uretidiones

Patent metadata

Field	Value
Publication number	US-9102785-B2
Application number	US-41142909-A
Country	US
Kind code	B2
Filing date	Mar 26, 2009
Priority date	Apr 11, 2008
Publication date	Aug 11, 2015
Grant date	Aug 11, 2015

Abstract

Curable compositions based on polyuretidiones, polythiols and photoactivable bases are disclosed. Also a process for generating isocyanate groups by exposing uretidiones to radiation in the range of 100-315 nm is disclosed. The process can be used in a dual curing system for curing compositions that comprise groups that under go photoinduced polymerizations and active hydrogen groups that react with the generated isocyanates.

First claim

What is claimed:

1. A curable composition comprising
(a) a polyuretidione that contains from 5 to 45% by weight of uretidione groups; 10 to 55% by weight of urethane groups; and less than 2% by weight of isocyanate groups, the percentages by weight being based on total weight of uretidione, urethane and isocyanate groups;
(b) a polythiol; and
(c) a photoactivable nitrogen containing base.

2. The composition of claim 1 in which the polyuretidione contains at least 2 uretidione groups.

3. The composition of claim 1 in which the polyuretidione contains from 2 to 10 uretidione groups.

4. The composition of claim 1 in which the polyuretidione is prepared by reacting a polyisocyanate containing 1 or more uretidione groups with at least one polyol and optionally a blocking agent for isocyanate.

5. The composition of claim 4 in which the polyisocyanate contains from 4 to 20 carbon atoms.

6. The composition of claim 5 in which the polyisocyanate is a (cyclo) aliphatic polyisocyanate.

7. The composition of claim 6 in which the polyisocyanate is a diisocyanate.

8. The composition of claim 7 in which the diisocyanate is isophorone diisocyanate.

9. The composition of claim 1 in which the polythiol is a monomeric polythiol having a molecular weight less than 550.

10. The composition of claim 1 in which the polythiol is a polymeric polythiol having a number average molecular weight greater than 700.

11. The composition of claim 1 in which the photoactivable nitrogen containing base upon exposure to ultraviolet light generates an amidine base.

12. The composition of claim 11 , in which the amidine base is selected from 1,8-diazobicyclo[5.4.0]undec-7-ene, 1,5-diazobicyclo[4.3.0]non-5-ene and tetramethylguanidine.

13. The composition of claim 11 in which the photoactivable nitrogen containing base has the following structure:

where Ar is an aromatic moiety.

14. The composition of claim 13 where Ar is a phenyl including a substituted phenyl moiety.

15. The composition of claim 1 in which the equivalent ratio of thiol to uretidione is from 0.5 to 1.5:1.

16. The composition of claim 1 in which the photoactivable nitrogen containing base is present in amounts from 0.5 to 5% by weight of resin solids of (a) and (b).

17. The composition of claim 1 which additionally contains a photo-sensitizer.

18. The composition of claim 17 in which the photosensitizer is present in amounts of 0.5-2 weight % based on weight of polyuretidione, polythiol, photoactivable nitrogen containing base and photosensitizer.

19. The composition of claim 17 in which the photosensitizer is selected from a benzophenone, and a thioxanthrone.

Assignees

• Martz Jonathan T
• Hayes Deborah E
• Singer Debra L
• Ppg Ind Ohio Inc

Inventors

• Martz Jonathan T
• Hayes Deborah E
• Singer Debra L

Classifications

• C08G18/2063 Primary

  having two nitrogen atoms in the condensed ring system · CPC title

• C08G18/798 Primary

  containing urethdione groups · CPC title

• C07C263/08

  from or via heterocyclic compounds, e.g. pyrolysis of furoxans · CPC title

• C08G18/2018 Primary

  having one nitrogen atom in the ring · CPC title

• C08G18/3876

  containing mercapto groups · CPC title