Polyurethane sealant compositions

• US 5,623,044 A
• Filed: 08/09/1996
• Issued: 04/22/1997
• Est. Priority Date: 10/13/1992
• Status: Expired due to Term

• Current Assignee: Essex Specialty Products Incorporated
• Original Assignee: Essex Specialty Products Incorporated
• Inventors: Chiao, Wen B.
• Primary Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US08/690,301
• Time in Patent Office: 256 Days
• Field of Search: 528/28, 528/44
• US Class Current: 528/28
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/12 using two or more compounds having active hydrogen in the first polymerisation step
• CPC Class Codes: C08G 18/307 Atmospheric humidity
• CPC Class Codes: C08G 18/4812 Mixtures of polyetherdiols with polyetherpolyols having at least three hydroxy groups
• CPC Class Codes: C08G 18/809 containing silicon
• CPC Class Codes: C08G 2190/00 Compositions for sealing or packing joints

Abstract

Described herein is a polyurethane sealant composition comprising (1) a urethane prepolymer having an isocyanate functionality of at least about 2.0 and a molecular weight of at least about 2,000; and (2) the reaction product of a secondary amino- or mercaptoalkoxy silane and a polyisocyanate having an average of at least one silane group and at least one isocyanate group per molecule and a molecular weight of less than about 2,000. The sealant composition of the invention is particularly useful in bonding glass to metal substrates when the glass substrate has not been primed with an application of a separate primer composition prior to the application of the sealant.

Claims

1. A polyurethane sealant composition comprising (1) a urethane prepolymer having an isocyanate functionality of from about 2.0 to about 4.0 and an isocyanate content of from about 1.0 to 10 percent:

and from about 0.5 to about 20 percent by weight based on the sealant composition of (2) a reaction product of a secondary aminoalkoxy silane and an aliphatic or aromatic polyisocyanate selected from the group consisting of ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane1,3-diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanato methyl cyclohexane, 2,4- and 2,6-hexahydrotolylene diisocyanate, hexahydro-1,3- and 1,4-phenylene diisocyanate, perhydro-2,5'"'"'- and 4,4'"'"'-diphenyl methane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4-and 2,6-tolylene diisocyanate, diphenyl methane-2,4'"'"'and 4,4'"'"'-diisocyanate, naphthylene-1,5-diisocyanate, triphenyl methane-4,4'"'"',4"-triisocyanate, polyphenyl polymethylene polyisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate and mixtures thereof, said reaction product having an average of at least one silane group and at least one isocyanate group per molecule and a molecular weight of less than about 2,000, wherein the sealant composition does not contain bitumin.

2. The polyurethane sealant composition of claim 1 wherein the isocyanate functionality of the prepolymer is from about 2.2 to about 3.0.

3. The polyurethane sealant composition of claim 1 wherein the isocyanate functionality of the prepolymer is from about 2.4 to about 3.0.

4. The polyurethane sealant of claim 1 wherein the polyisocyanate used to prepared component (2) is isopherone diisocyanate, a polymethylene polyphenyl isocyanate or an aliphatic polyisocyanate.

5. The polyurethane sealant composition of claim 1 wherein the isocyanate content of the prepolymer is in the range of from about 1.5 percent to about 5.0 percent.

6. The polyurethane sealant composition of claim 1 wherein the isocyanate content of the prepolymer is in the range of from about 1.8 percent to about 3.0 percent.

7. The polyurethane sealant composition of claim 1 wherein component (2) has at least 1.5 isocyanate groups and at least one silane group per molecule.

8. The polyurethane sealant composition of claim 1 wherein component (2) has at least two isocyanate groups and at least one silane group per molecule.

9. The polyurethane sealant composition of claim 1 wherein component (2) is present in an amount, based on the weight of the sealant composition, in the range of from about 1.0 percent to about 10 percent.

10. The polyurethane sealant composition of claim 1 wherein component (2) is present in an amount, based on the weight of the sealant composition, in the range of from about 2.0 percent to about 7 percent.

11. The polyurethane sealant composition of claim 1 wherein the polyisocyanate used to prepare component (2) has a molecular weight of less than about 2,000.

12. The polyurethane sealant composition of claim 4 wherein the polyisocyanate used to prepare component (2) has a molecular weight of less than about 1,000.

13. The polyurethane sealant composition of claim 12 wherein the polyisocyanate used to prepare component (2) is hexamethylene diisocyanate.

14. A polyurethane sealant composition according to claim 1 wherein the secondary aminoalkoxy silane corresponds to the following formula:

##STR2## wherein R is independently in each occurrence a divalent organic group;

R'"'"', R", R₁ and Ra are independently in each occurrence hydrogen or alkyl; and

m is an integer of from about 0 to about 2.

15. A polyurethane sealant composition according to claim 1 wherein the secondary aminoalkoxy silane is N,N'"'"'-bis((3-trimethoxysilyl)propyl)amine.

16. A polyurethane sealant composition comprising (1) a urethane prepolymer having an isocyanate functionality of at least 2.0 and an isocyanate content of from about 1.0 to 10 percent wherein isocyanate prepolymer is prepared from a polyisocyanate having a functionality of from about 2.0 to about 4.0 and a polyol having a functionality of from about 1.5 to about 4.0 and an equivalent weight of about 200 to about 3,500;

and from about 0.5 to about 20 percent by weight based on the sealant composition of (2) a reaction product of a secondary aminoalkoxy silane and an aliphatic or aromatic polyisocyanate selected from the group consisting of ethylene diisocyanate, 1,4tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane1,3-diisocyanate, cyclohexane-,1,3- and 1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanato methyl cyclohexane, 2,4- and 2,6-hexahydrotolylene diisocyanate, hexahydro-1,3- and 1,4-phenylene diisocyanate, perhydro-2,5'"'"'- and 4,4'"'"'-diphenyl methane diisocyanate, 1,3- and 1,4-phonylone diisocyanate, 2,4-and 2,6-tolylene diisocyanate, diphenyl methane-2,4'"'"'-and 4,4'"'"'-diisocyanate, naphthylene-1,5-diisocyanate, triphenyl methane-4,4'"'"',4"-triisocyanate, polyphenyl polymethylerie polyisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate and mixtures thereof, said reaction product having an average of at least one silane group and at least one isocyanate group per molecule and a molecular weight of less than about 2,000, wherein the sealant composition does not contain bitumin.

17. The polyurethane sealant composition of claim 16 wherein the functionality of the polyisocyanate is about 2.0 to about 3.0 or less and the functionality of the polyol is about 1.8 to about 3.0.

18. The polyurethane sealant composition of claim 17 wherein the isocyanate content of the prepolymer is in the range of from about 1.5 percent to about 5.0 percent.

19. The polyurethane sealant composition of claim 17 wherein the isocyanate content of the prepolymer is in the range of from about 1.8 percent to about 3.0 percent.

20. The polyurethane sealant composition of claim 18 wherein Component (2) has at least 1.5 isocyanate groups and at least one silane group per molecule.

21. The polyurethane sealant composition of claim 18 wherein Component (2) has at least two isocyanate groups and at least one silane group per molecule.

22. The polyurethane sealant composition of claim 18 wherein Component (2) is present in an amount, based on the weight of the sealant composition, in the range of from about 1.0 percent to about 10 percent.

23. The polyurethane sealant composition of claim 18 wherein the polyisocyanate used to prepare Component (2) has a molecular weight of less than about 2,000.

24. A polyurethane sealant composition according to claim 16 wherein the secondary aminoalkoxy silane corresponds to the following formula:

##STR3## wherein R is independently in each occurrence a divalent organic group;

R'"'"', R", R₁ and Ra are independently in each occurrence hydrogen or alkyl.

25. A polyurethane sealant composition according to claim 16 wherein the secondary aminoalkoxy silane is N,N'"'"'-bis((3-trimethoxysilyl)propyl)amine.

26. The polyurethane sealant of claim 16 wherein the polyisocyanate used to prepare Component (2) is isopherone diisocyanate, a polymethylene polyphenyl isocyanate or an aliphatic polyisocyanate.