Epoxy adhesive having improved impact resistance

A curable adhesive composition comprising :a pre-reacted reaction product of

• A) a pre-reacted reaction product of
• (a) about 0.5 to about 1 equivalent of an epoxy resin which is solid at room temperature prepared from bisphenol A or bisphenol F and epichlorohydrin having an epoxide equivalent weight of from about 400 to about 700;
• (b) about 0.5 to about 1 equivalent of an epoxy resin which is liquid at room temperature prepared from bisphenol A or bisphenol F and epichlorohydrin having an epoxide equivalent weight of from about 150 to about 220;
• and
• (c) about 0.125 to about 0.5 equivalent of an amino-terminated polyalkylene glycol selected from the group consisting of polyethylene and polypropylene glycols;
• wherein said epoxy resins (a) and (b) are present in an amount such that a stoichiometric excess of at least 1 equivalent of epoxy groups over the amino groups is provided, said amino-terminated polyalkylene glycol comprising
• i) a linear amino-terminated polyethylene glycol, or
• ii) a linear amino-terminated polypropylene glycol, or,
• iii) a linear amino-terminated polyethylene glycol and a trifunctional amino-terminated polypropylene glycol;
• wherein about 4 to about 40% of the epoxy equivalents of the total epoxy resin component are replaced by an adduct of dimeric fatty acides on epoxy resins prepared from diglycidyl ethers of bisphenol A or F, or by an adduct of carboxyl-terminated butadiene-nitrile rubber on epoxy resins prepared from diglycidyl ethers of bisphenol A or F;
• B) an acrylate terminated urethane resin which comprises the reaction product of an isocyanate terminated urethane prepolymer and an isocyanate reactive acrylate or methacrylate;
• C) a latent curing agent;
• and
• D) an expanding agent comprising hollow plastic microspheres.

A curable adhesive composition which comprises:

• A) a reaction product of a polyepoxide resin having at least two 1,2-epoxy groups per molecule with polyoxy alkylene amine and, optionally, an adduct of carboxy terminated butadiene-nitrile rubber (BNR);
• B) an acrylate terminated urethane resin;
• and
• C) a latent curing agent.

A curable adhesive which comprises:

• A) a prepolymer reaction mixture of
• (a) an epoxy resin, an epoxy resin which is solid at room temperature prepared from bisphenol A or bisphenol F and epichlorohydrin having an epoxide equivalent weight of from about 400 to about 700;
• (b) an epoxy resin which is liquid at room temperature prepared from bisphenol A or bisphenol F and epichlorohydrin 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, or a carboxyl terminated butadienenitrile resin, or mixtures thereof;
• B) an acrylate-terminated urethane resin;
• C) a latent curing agent;
• and
• D) an expanding agent comprising hollow microspheres.

A method of making a composite article which comprises:

• contacting a surface with a curable adhesive which comprises:
• A) a prepolymer reaction mixture of
• (a) epoxy resin or resins prepared from bisphenol A or bisphenol F and epichlorohydrin having an epoxide equivalent weight of from about 150 to about 700;
• (b) an amino-terminated polyalkylene glycol selected from the group consisting of polyethylene and polypropylene glycols, or a carboxyl terminated butadiene nitrile resin, or mixtures thereof,
• B) an acrylate-terminated urethane resin;
• and
• C) a latent curing agent;
• and curing the adhesive in contact with the surface to prepare a composite article.