Thermosettable compositions useful for producing structural adhesive foams

• US 20050043420A1
• Filed: 09/20/2004
• Published: 02/24/2005
• Est. Priority Date: 04/27/2001
• Status: Abandoned Application

• Current Assignee: Rajat K. Agarwal
• Original Assignee: Rajat K. Agarwal
• Inventors: Agarwal, Rajat K.
• Application Number:
  US10/945,384
• Publication Number:
  US 20050043420A1
• Time in Patent Office: Days
• US Class Current: 521/82
• CPC Class Codes: C08G 18/581 Reaction products of epoxy resins with less than equivalent amounts of compounds containing active hydrogen added before or during the reaction with the isocyanate component with amines C08G18/584
• CPC Class Codes: C08G 2170/60 Compositions for foaming; Foamed or intumescent adhesives
• CPC Class Codes: C08G 2190/00 Compositions for sealing or packing joints

Abstract

The use of an adduct of an isocyanate resin and an isocyanate-reactive epoxy resin in an expandable thermosettable composition helps to reduce the tackiness of the composition and also increases its dimensional stability, as compared to compositions in which only non-adducted epoxy resins are present.

Claims

1. A storage-stable one-part expandable thermosettable composition useful for producing a structural adhesive foam comprising:

(a) at least one adduct of at least one isocyanate resin and at least one epoxy resin bearing at least one isocyanate-reactive functional group per molecule;

(b) one or more blowing agents, wherein said blowing agents are latent blowing agents which are only activated upon heating to an elevated temperature but which remain inactive at normal storage temperatures; and

(c) one or more epoxy curatives, wherein said epoxy curatives are latent curatives that activate only upon heating to an elevated temperature but which do not catalyze curing of the thermosettable composition to any significant extent at normal storage temperatures.

2. The composition of claim 1 wherein the epoxy resin is a glycidyl ether of a polyhydric phenol.

3. The composition of claim 2 wherein the polyhydric phenol is bisphenol A.

4. The composition of claim 1 wherein the epoxy resin is a diglycidyl ether of bisphenol A having an epoxy equivalent weight of from about 180 to about 300.

5. The composition of claim 1 wherein at least one isocyanate resin is an aliphatic polyisocyanate.

6. The composition of claim 1 wherein at least one isocyanate resin has at least three isocyanate groups per molecule.

7. The composition of claim 1 wherein at least one isocyanate resin is a timer of a diisocyanates.

8. The composition of claim 1 wherein at least one isocyanate resin is an HDI trimer.

9. The composition of claim 1 additionally comprising one or more urethane catalysts.

10. The composition of claim 1 additionally comprising one or more urethane catalysts selected from the group consisting of bismuth compounds, tin compounds, and combinations thereof.

11. The composition of claim 1 additionally comprising hollow glass microspheres.

12. The composition of claim 1 additionally comprising one or more rubbers.

13. The composition of claim 1 additionally comprising one or more adhesion promoters selected from the group consisting of silanes, titanates, zirconates, and mixtures thereof.

14. The composition of claim 1 wherein one or more of the epoxy curatives are selected from the group consisting of guanidines, amine epoxy adducts and mixtures thereof.

15. The composition of claim 1 additionally comprising one or more fillers.

16. The composition of claim 1 additionally comprising one or more fillers selected from the group consisting of calcium carbonate, wollastonite, glass fibers, polyaramid fibers and mixtures thereof.

17. The composition of claim 1 additionally comprising one or more thixotropic agents.

18. The composition of claim 1 additionally comprising one or more thixotropic agents selected from the group consisting of fumed silica, calcium carbonate and mixtures thereof.

19. The composition of claim 1 wherein one or more of the blowing agents is selected from the group consisting of azo compounds, sulphonylhydrazides, expandable thermoplastic shells having one or more volatile compounds contained therein, and mixtures thereof.

20. The composition of claim 1 additionally comprising one or more blowing agent accelerators.

29. A method of filling and reinforcing a hollow member of an assembly comprising the steps of:

(a) placing a portion of the thermosettable expandable composition of claim 1 within said hollow member; and

(b) heating said portion of said thermosettable expandable composition for a time and at a temperature effective to expand and cure said thermosettable expandable composition.

30. The method of claim 29 wherein said portion is fastened to a carrier.

21. A storage-stable one-part expandable thermosettable composition useful for producing a structural adhesive foam comprising:

(a) at least one adduct of at least one isocyanate resin having at least two isocyanate groups per molecule and at least one liquid or semi-solid epoxy resin bearing at least one hydroxyl group per molecule, wherein said at least one liquid or semi-solid epoxy resin is a glycidyl ether of bisphenol A;

(b) one or more blowing agents, wherein said blowing agents are latent blowing agents which are only activated upon heating to an elevated temperature but which remain inactive at normal storage temperatures;

(c) one or more epoxy curatives, wherein said epoxy curatives are latent curatives that activate only upon heating to an elevated temperature but which do not catalyze curing of the thermosettable composition to any significant extent at normal storage temperature; and

(d) one or more additional components selected from the group consisting of;

(i) urethane catalysts;

(ii) hollow glass microspheres;

(iii) rubbers;

(iv) adhesion promoters;

(v) fillers;

(vi) thixotropic agents; and

(vii) epoxy resins other than said at least one liquid or semi-solid epoxy resin adducted with said isocyanate resin.

22. The expandable thermosettable composition of claim 21, wherein said expandable thermosettable composition is prepared using 30 to 90 wt % of epoxy resin, 0.1 to 15 wt % of said blowing agent, 0.1 to 20 wt % of said at least one isocyanate resin, and 0.1 to 20 wt % of said epoxy curatives.

23. The expandable thermosettable composition of claim 21 wherein the said at least one liquid or semi-solid epoxy resin is a diglycidyl ether of bisphenol A having an epoxy equivalent weight of from about 180 to about 300.

24. The expandable thermosettable composition of claim 21 wherein at least one isocyanate resin is an aliphatic polyisocyanate.

25. The expandable thermosettable composition of claim 21 wherein at least one isocyanate resin has at least three isocyanate groups per molecule.

26. The expandable thermosettable composition of claim 21 wherein at least one isocyanate resin is a trimer of a diisocyanate.

27. The expandable thermosettable composition of claim 21 wherein at least one isocyanate resin is an HDI trimer.

28. A storage-stable one-part expandable thermosettable composition useful for producing a structural adhesive foam comprising;

(a) 40 to 70 wt % of one or more epoxy resins;

(b) 0.5 to 8 wt % of one or more blowing agents, wherein said blowing agents are latent blowing agents which are only activated upon heating to an elevated temperature but which remain inactive at normal storage temperatures;

(c) 0.5 to 5 wt % of one or more isocyanate resins;

(d) 1 to 10 wt % of one or more epoxy curatives, wherein said epoxy curatives are latent curatives that activate only upon heating to an elevated temperature but which do not catalyze curing of the thermosettable composition to any significant extent at normal storage temperature;

(e) 1 to 10 wt % of one or more rubbers;

(f) 0.01 to 1 wt % of one or more adhesion promoters;

(g) 0.01 to 0.5 wt % of one or more urethane catalysts;

(h) 0 to I wt % of one or more blowing agent accelerators;

(i) 10 to 40 wt % of hollow glass microspheres;

(j) 1 to 20 wt % of one of more fillers; and

(k) 0.1 to 5 wt % of one or more thixotropic agents;

wherein at least a portion of the epoxy resins are liquid or semi-solid epoxy resins having at least one isocyanate-reactive functional group per molecule which have been reacted with at least a portion of the isocyanate resins to form an adduct.

31. A method of making a storage-stable one-part expandable thermosettable composition useful for producing a structural adhesive foam, said method comprising:

(a) combining at least one liquid or semi-solid epoxy resin bearing at least one isocyanate-reactive functional group, one or more blowing agents, wherein said blowing agents are latent blowing agents which are only activated upon heating to an elevated temperature but which remain inactive at normal storage temperature, and one or more epoxy curatives, wherein said epoxy curatives are latent curatives that activate only upon heating to an elevated temperature but which do not catalyze curing of the thermosettable composition to any significant extent at normal storage temperature, to form a uniform mixture; and

(b) reacting at least a portion of the liquid or semi-solid epoxy resin in said mixture with at least one isocyanate resin to form an adduct.