초록 ▼

Structural adhesives are prepared from a chain extended elastomeric toughener that contains urethane and/or urea groups, and have terminal isocyanate groups that are capped with a phenol, a polyphenol or an aminophenol compound. The adhesives have very good storage stability and cure to form cured a

Structural adhesives are prepared from a chain extended elastomeric toughener that contains urethane and/or urea groups, and have terminal isocyanate groups that are capped with a phenol, a polyphenol or an aminophenol compound. The adhesives have very good storage stability and cure to form cured adhesives that have good lap shear and impact peel strengths.

대표청구항 ▼

1. A one-part structural adhesive comprising: A) at least one epoxy resin;B) a reactive elastomeric toughener containing capped isocyanate groups; andC) one or more epoxy curing agents;wherein all reactive elastomeric tougheners containing capped isocyanate groups present in the one-part structural

1. A one-part structural adhesive comprising: A) at least one epoxy resin;B) a reactive elastomeric toughener containing capped isocyanate groups; andC) one or more epoxy curing agents;wherein all reactive elastomeric tougheners containing capped isocyanate groups present in the one-part structural adhesive are formed bya) reacting an excess of a polyisocyanate with a 300-3000 equivalent weight polyol or with a mixture of a 300-3000 equivalent weight polyol and a branching agent, to form an isocyanate-terminated prepolymer;b) reacting the isocyanate-terminated prepolymer with a chain extender to produce a chain extended, isocyanate-terminated prepolymer, andc) capping 100% of the terminal isocyanate groups of the chain extended, isocyanate-terminated prepolymer with a capping agent selected from a monophenol, a polyphenol and an aminophenol. 2. The structural adhesive of claim 1, wherein the 300-3000 equivalent weight polyol is a polyether, a hydroxyl-terminated polybutadiene or a mixture of a polyether and a hydroxyl-terminated polybutadiene. 3. The structural adhesive of claim 1, wherein the chain extender contains two phenolic hydroxyl groups. 4. The structural adhesive of claim 1 wherein the capping agent is a monophenol. 5. The structural adhesive of claim 1 wherein the capping agent is a polyphenol. 6. The structural adhesive of claim 1 wherein the capping agent is an aminophenol. 7. The structural adhesive of claim 1, wherein the epoxy resin includes at least one diglycidyl ether of a polyhydric phenol. 8. The structural adhesive of claim 1, which contains at least one epoxide-terminated liquid rubber. 9. The structural adhesive of claim 1, further comprising a latent catalyst which becomes active only upon exposure to elevated temperatures. 10. The structural adhesive of claim 9 wherein the latent catalyst is 2,4,6-tris(dimethylaminomethyl)phenol integrated into a poly(p-vinylphenol) matrix or 2,4,6-tris(dimethylaminomethyl)phenol integrated into a novolac resin. 11. The structural adhesive of claim 1 wherein the curing agent includes one or more of a boron trichloride/amine complex, a boron trifluoride/amine complex, dicyandiamide, melamine, diallylmelamine, acetoguanamine, benzoguanamine, 3-amino-1,2,4-triazole, adipic dihydrazide, stearic dihydrazide, isophthalic dihydrazide, semicarbazide, cyanoacetamide, and diaminodiphenylsulphones. 12. The structural adhesive of claim 1 further comprising one or more of calcium carbonate, calcium oxide, talc, carbon black, textile fibers, glass particles, glass fibers, aramid pulp, boron fibers, carbon fibers, a mineral silicate, mica, powdered quartz, hydrated aluminum oxide, bentonite, wollastonite, kaolin, fumed silica, silica aerogel, a polyurea compound, a polyamide compound, aluminum powder, iron powder, and microballoons having an average particle size of up to 200 microns and density of up to 0.2 g/cc. 13. A method comprising applying the structural adhesive of claim 1 to the surfaces of two members, and curing the structural adhesive to form an adhesive bond between the two members. 14. A one-part structural adhesive comprising: A) at least one epoxy resin;B) a reactive elastomeric toughener containing capped isocyanate groups; andC) one or more epoxy curing agents;wherein all reactive elastomeric tougheners containing capped isocyanate groups present in the one-part structural adhesive are formed bya) reacting an excess of 1,6-hexamethylene diisocyanate with a 300-3000 equivalent weight polytetrahydrofuran, to form an isocyanate-terminated prepolymer;b) reacting the isocyanate-terminated prepolymer with o,o′-diallylbisphenol A to produce a chain extended, isocyanate-terminated prepolymer, andc) capping 100% of the terminal isocyanate groups of the chain extended, isocyanate-terminated prepolymer with a capping agent selected from o,o′-diallylbisphenol A and allylphenol.