Expandable epoxy resin-based systems modified with thermoplastic polymers

• US 20040266899A1
• Filed: 06/14/2004
• Published: 12/30/2004
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel AG & Co KGaA
• Inventors: Puckett, Michael, Muenz, Xaver, Agarwal, Rajat K., Ferguson, Gregory A., Leeb, Thomas
• Granted Patent: US 7,473,717 B2
• Time in Patent Office: Days
• US Class Current: 521/135
• CPC Class Codes: C08G 59/40 characterised by the curing agents used
• CPC Class Codes: C08J 2363/00 Characterised by the use of epoxy resins; Derivatives of epoxy resins
• CPC Class Codes: C08J 2400/22 Thermoplastic resins
• CPC Class Codes: C08J 9/0061 characterized by the use of several polymeric components
• CPC Class Codes: C08J 9/102 Azo-compounds
• CPC Class Codes: C08J 9/32 from compositions containing microballoons, e.g. syntactic foams
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]

Abstract

Expandable thermosettable compositions containing at least one epoxy resin, at least one finely divided thermoplastic polymer powder, at least one blowing agent, at least one curing agent, and at least one filler are suitable for the production of thermosetting laminated bodies with a tacky surface. These laminated bodies can be produced and handled in a simple manner and are suitable for stiffening and reinforcing flat structural components, in particular vehicle body structural components, such as vehicle body frames, doors, trunk lids, engine hoods and/or roof components in automobile construction. The expandable thermosettable compositions are also suitable for the production of thermosetting, thermally expandable shaped articles for reinforcing hollow structural members by the injection molding process. In preferred embodiments, the composition is injected onto a metallic or thermoplastic carrier. These thermally expandable shaped articles are especially useful in the production of automobiles and other vehicles to maintain or increase the strength of structural members such as rockers, pillars, radiator support beams, doors, reinforcing beams, and the like.

Claims

1. An expandable thermosettable composition comprising:

(a) at least one epoxy resin;

(b) at least one finely divided thermoplastic polymer powder;

(c) at least one blowing agent;

(d) at least one curative; and

(e) at least one filler.

2. The expandable thermosettable composition of claim 1, comprising additionally a flexibilizing agent.

3. The expandable thermosettable composition of claim 1, comprising additionally a reactive diluent.

4. The expandable thermosettable composition of claim 1, wherein at least one epoxy resin has a molecular weight of greater than 350.

5. The expandable thermosettable composition of claim 1, wherein at least one epoxy resin is a liquid glycidyl ether of a polyhydric phenol.

6. The expandable thermosettable composition of claim 1, additionally comprising at least one flexibilizing agent selected from the group consisting of rubber-modified epoxy resins, polyurethane-modified epoxy resins, adducts of amino-terminated polyoxyalkylenes and polyepoxides, adducts of dimer fatty acids and bisphenol A diglycidyl ethers, adducts of polyether polyols on epoxy resins, polysulfide- and polymercaptan-modified epoxy resins, and copolymers of acrylonitrile with butadiene and/or isoprene and optionally (meth)acrylic acid.

7. The expandable thermosettable composition of claim 1, additionally comprising at least one reactive diluent selected from the group consisting of mono-, di- and triglycidyl ethers of C₆ to C₁₄ monoalcohols, alkylphenols, cashew nut shell oil, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol, and trimethylolpropane, and glycidyl esters of C₆- to C₂₄-carboxylic acids.

8. The expandable thermosettable composition of claim 1, wherein at least one thermoplastic polymer powder is comprised of a polymer selected from the group consisting of vinyl acetate homo- and copolymers, ethylene/vinyl acetate copolymers, vinyl chloride homo- and copolymers, styrene homo- and copolymers, (meth)acrylate homo- and copolymers and polyvinylbutyrals and has an average particle size of less than 100 μ

m.

9. The expandable thermosettable composition of claim 1, wherein the thermoplastic polymer powder is present in an amount from 0.1 wt % to 40 wt %.

10. The expandable thermosettable composition of claim 1, comprising at least one thermoplastic polymer powder having a core-shell structure.

11. The expandable thermosettable composition of claim 1, comprising at least one thermoplastic polymer powder having a core-shell structure and comprising an acrylic resin.

12. The expandable thermosettable composition of claim 1, wherein at least one thermoplastic polymer powder has a glass transition temperature of from 70°

C. to 120°

C.

13. The expandable thermosettable composition of claim 1, comprising at least one curative selected from the group consisting of guanidines, substituted guanidines, substituted ureas, melamine resins, guanamine derivatives, cyclic tertiary amines, aromatic amines, and adducts of amines on epoxy resins.

14. The expandable thermosettable composition of claim 1, comprising cyanoguanidine (dicyanodiamide) in an amount of up to 5% by weight.

15. The expandable thermosettable composition of claim 1, comprising additionally at least one accelerator selected from the group consisting of 2-ethyl-2-methylimidazole, N-butylimidazole, benzimidazole, N—

C₁- to C₁₂-alkylimidazoles, N-arylimidazoles, triazine derivatives and imidazole/triazine compounds.

16. The expandable thermosettable composition of claim 1, comprising at least one chemical blowing agent selected from the group consisting of azobisisobutyronitrile, azodicarbonamide, di-nitroso-pentamethylenetetramine, 4,4′

-oxybis(benzenesulfonic acid hydrazide), diphenyl-sulfone-3,3′

-disulfohydrazide, benzene-1,3-disulfohydrazide and p-toluenesulfonyl semicarbazide.

17. The expandable thermosettable composition of claim 1, comprising at least one physical blowing agent comprising expandable hollow microbeads based on polyvinylidene chloride copolymers or acrylonitrile/(meth)acrylate copolymers.

18. The expandable thermosettable composition of claim 1, comprising additionally one or more fillers, at least a portion of the fillers being at least one lightweight filler selected from the group consisting of hollow metal beads, hollow glass beads, fly ash, hollow beads of plastic based on phenolic resins, epoxy resins or polyesters, hollow microbeads with a wall material selected from the group consisting of (meth)acrylic acid ester copolymers, polystyrene, styrene/(meth)acrylate copolymers, polyvinylidene chloride and copolymers of vinylidene chloride with acrylonitrile and/or (meth)acrylic acid esters, hollow ceramic beads, and organic lightweight fillers of natural origin.

19. The expandable thermosettable composition of claim 1, comprising additionally one or more types of fibers selected from the group consisting of aramid fibers, carbon fibers, metal fibers, glass fibers, polyamide fibers, polyethylene fibers and polyester fibers.

20. The expandable thermosettable composition of claim 1, comprising

21. The expandable thermosettable composition of claim 1 wherein at least one thermoplastic polymer powder has a core-shell structure and at least one blowing agent is a chemical blowing agent selected from the group consisting of azobisisobutyronitrile, azodicarbonamide, di-nitroso-pentamethylenetetramine, 4,4′

-oxybis(benzenesulfonic acid hydrazide), diphenyl-sulfone-3,3′

-disulfohydrazide, benzene-1,3-disulfohydrazide and p-toluenesulfonyl semicarbazide.

22. The expandable thermosettable composition of claim 1, wherein at least one thermoplastic polymer powder has a core-shell structure with the core comprising a reactive thermoplastic containing functional groups selected from the group consisting of carboxyl, carboxylic acid anhydride, and imidazole and the shell comprising a non-reactive thermoplastic.

23. The expandable thermosettable composition of claim 1, wherein said at least one thermoplastic polymer powder comprises 3 to 15 weight % of the expandable thermosettable composition.

24. A process for stiffening and/or reinforcing a metallic substrate, comprising the steps of:

a) applying a laminate body comprised of a first layer comprised of the expandable thermosettable composition of claim 1 and a second layer comprised of at least one reinforcing agent onto said metallic substrate; and

b) heating the laminate body to a temperature effective to cause foaming and curing of the expandable thermosettable composition.

25. The process of claim 24 wherein said first layer is tacky on at least one side at room temperature and can be stacked without a change in dimensions and shape at temperatures of up to 50°

C.

26. The process of claim 24 wherein the metallic substrate is a vehicle body structural component selected from the group consisting of frames, doors, trunk lids, engine hoods and roofs.

27. The process of claim 24 wherein said second layer is comprised of a textile sheet like structure or a metal tape.

28. A process for stiffening and/or reinforcing a structural component having a hollow space or metallic substrate therein, said process comprising:

a) injection molding the expandable thermosettable composition of claim 1 to form a molding;

b) fixing the molding to the metallic substrate or introducing the molding into the hollow space; and

c) heating the molding to a temperature effective to cause foaming and curing of the expandable thermosettable composition.

29. The process of claim 28, wherein said molding is not tacky at room temperature.

30. The process of claim 28, wherein said expandable thermosettable composition is injection molded onto a carrier.

31. A laminate body comprised of a first layer comprised of the expandable thermosettable composition of claim 1 and a second layer comprised of at least one reinforcing agent.

32. A molding comprised of the expandable thermosettable composition of claim 1 and a carrier.