Novel copolyester-polyepoxide compositions
AssigneeAllied Chemical Corporation
InventorsDusan C. Prevorsek, Shaul M. Aharoni
Life of this patent
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Abstract
Novel copolyester-polyepoxide compositions possessing a high green strength and tack before curing and characterized by having a single discernible glass transition temperature are produced. The compositions are composed of a copolyester and a polyepoxide mixture containing high, intermediate and low molecular weight components. They are especially useful as gap-filling adhesives and for various other adhesive applications. Methods of preparation are also described.
Claims19
A copolyester-polyepoxide composition characterized by possessing a single discernible glass transition temperature before curing as measured by differential scanning calorimetry comprising:
- A. a copolyester having a number average molecular weight in the range from about 6,000 to about 50,000;
- and
- B. a polyepoxide mixture comprising high, intermediate and low molecular weight components wherein
- a. about 25 to 75 weight percent of said mixture is said high molecular weight component having a weight average molecular weight in the range of above 25,000 to about 120,000 and an epoxide equivalent in the range from above 10,000 to about 60,000;
- b. about 15 to 65 weight percent of said mixture is said intermediate molecular weight component having a weight average molecular weight in the range of above 3,000 to 25,000 and an epoxide equivalent in the range from above 1,600 to 10,000;
- c. about 5 to 35 weight percent of said mixture is said low molecular weight component having a weight average molecular weight in the range of about 150 to 3,000 and an epoxide equivalent in the range from about 50 to 1,600, said polyepoxide mixture being present in an amount of at least 50% but not more than about 200% by weight based on said copolyester;
- and
- C. an epoxy curing agent present in the amount from 0 to about 1.1 equivalents per epoxy equivalent.
A process of preparing a copolyester-polyepoxide composition which possesses a single discernible glass transition temperature comprising:
- a. dissolving a copolyester in a solvent therefor;
- b. dissolving a polyepoxide in a solvent therefor which is miscible with the solvent used for the copolyester;
- c. mixing together the solutions of copolyester and polyepoxide with adequate agitation to produce a homogeneous solution;
- and
- d. recovering the copolyester-polyepoxide composition from the solution by removal of the solvent from the copolyester-polyepoxide composition at such a rate that it exceeds the rate of phase separation between the copolyester and polyepoxide wherein said copolyester-polyepoxide composition comprises:
- A. a copolyester having a number average molecular weight in the range from about 6,000 to about 50,000;
- and
- B. a polyepoxide mixture comprising high, intermediate and low molecular weight components wherein
- a. about 25 to 75 weight percent of said mixture is said high molecular weight component having a weight average molecular weight in the range of about 25,000 to about 120,000 and an epoxide equivalent in the range from above 10,000 to about 60,000;
- b. about 15 to 65 weight percent of said mixture is said intermediate molecular weight component having a weight average molecular weight in the range of above 3,000 to 25,000 and an epoxide equivalent in the range from above 1,600 to 10,000;
- c. about 5 to 35 weight percent of said mixture is said low molecular weight component having a weight average molecular weight in the range of about 150 to 3,000 and an epoxide equivalent in the range from about 50 to 1,600, said polyepoxide being present in an amount of at least 50% but not more than about 200% by weight based on said copolyester;
- and
- C. an epoxy curing agent present in the amount from 0 to about 1.1 equivalents per epoxy equivalent.
Dependencies are inferred from the claim text.