Epoxy adhesive having improved impact resistance

A curable adhesive comprising:

• A) an epoxy-based prepolymer which comprises the reaction product of
• a. a first epoxy resin which is solid at room temperature and which is a diglycidyl ether of bisphenol A or bisphenol F, having an epoxide equivalent weight of from about 400 to about 700;
• b. a second epoxy resin which is liquid at room temperature and which is a diglycidyl ether bisphenol A or bisphenol F, having an epoxide equivalent weight of from about 150 to about 220;
• and
• c. an amino-terminated polyalkylene glycol selected from the group consisting of polyethylene and polypropylene glycols;
• B) an acrylate terminated urethane resin which comprises the reaction product of an isocyanate terminated urethane prepolymer and an isocyanate reactive acrylate or methacrylate, wherein the isocyanate terminated urethane prepolymer is obtained by reaction of a polyol having a number average molecular weight of at least about 400 and a polyfunctional isocyanate;
• C) a heat-activated latent curing agent;
• and
• D) an expanding agent comprising hollow plastic microspheres.

A curable adhesive which comprises:

• A) a reaction product of a polyepoxide resin having at least two 1,2-epoxy groups per molecule with an amino-terminated polyalkylene glycol and, optionally, an epoxy adduct of a carboxyl-terminated butadiene-nitrile rubber;
• B) an acrylate-terminated urethane resin which comprises the reaction product of an isocyanate terminated urethane prepolymer and an isocyanate reactive (meth)acrylate, wherein the isocyanate terminated urethane prepolymer is obtained by reaction of a polyol having a number average molecular weight of at least about 400 and a polyfunctional isocyanate;
• and
• C) a heat-activated latent curing agent.

A curable adhesive which comprises:

• A) an epoxy-based prepolymer comprising the reaction product of
• a. a first epoxy resin which is solid at room temperature and which is a diglycidyl ether of bisphenol A or bisphenol F, having an epoxide equivalent weight of from about 400 to about 700;
• b. a second epoxy resin which is liquid at room temperature and which is a diglycidyl ether of bisphenol A or bisphenol F, having an epoxide equivalent weight of from about 150 to about 220;
• and
• c. a co-reactant selected from the group consisting of amino-terminated polyalkylene glycols, carboxyl-terminated butadiene-nitrile resins, and mixtures thereof;
• B) an acrylate-terminated urethane resin;
• C) a heat-activated latent curing agent;
• and
• D) an expanding agent comprising hollow microspheres.