Bonding method utilizing polyester adhesive exhibiting "open time"

Claim 1

A method for forming a strong bond between a substrate and a thermoplastic copolyester comprising (1) melting a thermoplastic segmented copolyester having an open time of at least about 1/4 minute at 20° C. and consisting essentially of from about 5 to 75 percent by weight of amorphous ester units and 95 to 25 percent by weight of crystallizable ester units joined through ester linkages, the crystallizable ester units being or the formula ##STR4## and the amorphous ester units being of the formula ##STR5## wherein R 1 consists of residues of one or more diacids selected from saturated aliphatic dicarboxylic acids containing from 4 to 10 carbon atoms and aromatic dicarboxylic acids selected from terephthalic acid, isophthalic acid, phthalic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, 4,4'-diphenylthioether dicarboxylic acid and 4,4'-diphenylamine dicarboxylic acid, R 2 consists of residues of one or more saturated aliphatic diols containing from 2 to 12 carbon atoms, R 3 is R 1 or R 5 , R 4 is R 2 or R 6 , R 5 consists of the divalent radicals containing from about 22 to 50 carbon atoms which remain after removal of the carboxyl groups from saturated aliphatic dimer acids and R 6 consists of the divalent radicals remaining after removal of the hydroxyl groups of long chain aliphatic diols having an average molecular weight of 200 to 4000, provided that at least one of R 3 and R 4 is each amorphous ester unit is R 5 or R 6 , and provided that when R 1 is aromatic, R 2 contains from 6 to 12 carbon atoms and the amorphous content is 50-75 percent by weight, the said copolyester having a DTA melting temperature of from about 25° to 150° C., an inherent viscosity of at least 0.5 dl/g at 25° C., as measured in 0.3 g/dl solutions of polymer in chloroform at 25° C., substantially complete solubility in toluene at 25° C. in the ratio of about 10 percent by weight of copolyester and 90% by weight of solvent, a tensile strength of 100-400 kg/cm 2 , an elongation at break of 400-1000 percent, a T-peel adhesion to vinyl of at least 0.9 kg/cm of width and a DTA glass transition temperature, T g , below -25° C., (2) cooling the copolyester below its melting temperature, (3) bringing the copolyester into contact with the substrate which is at a temperature below the copolyester melting temperature and while the copolyester is still open, and (4) maintaining the copolyester and the substrate in contact until the copolyester has reverted to its solid, non-bondable state.

Claim 2

A method for forming a strong bond between a substrate and a thermoplastic copolyester comprising (1) melting a thermoplastic segmented copolyester having an open time of at least about 1/4 minute at 20° C. and consisting essentially of from about 5 to 75 percent by weight of amorphous ester units and 95 to 25 percent by weight of crystallizable ester units joined through ester linkages, the crystallizable ester units being or the formula ##STR4## and the amorphous ester units being of the formula ##STR5## wherein R 1 consists of residues of one or more diacids selected from saturated aliphatic dicarboxylic acids containing from 4 to 10 carbon atoms and aromatic dicarboxylic acids selected from terephthalic acid, isophthalic acid, phthalic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, 4,4'-diphenylthioether dicarboxylic acid and 4,4'-diphenylamine dicarboxylic acid, R 2 consists of residues of one or more saturated aliphatic diols containing from 2 to 12 carbon atoms, R 3 is R 1 or R 5 , R 4 is R 2 or R 6 , R 5 consists of the divalent radicals containing from about 22 to 50 carbon atoms which remain after removal of the carboxyl groups from saturated aliphatic dimer acids and R 6 consists of the divalent radicals remaining after removal of the hydroxyl groups of long chain aliphatic diols having an average molecular weight of 200 to 4000, provided that at least one of R 3 and R 4 is each amorphous ester unit is R 5 or R 6 , and provided that when R 1 is aromatic, R 2 contains from 6 to 12 carbon atoms and the amorphous content is 50-75 percent by weight, the said copolyester having a DTA melting temperature of from about 25° to 150° C., an inherent viscosity of at least 0.5 dl/g at 25° C., as measured in 0.3 g/dl solutions of polymer in chloroform at 25° C., substantially complete solubility in toluene at 25° C. in the ratio of about 10 percent by weight of copolyester and 90% by weight of solvent, a tensile strength of 100-400 kg/cm 2 , an elongation at break of 400-1000 percent, a T-peel adhesion to vinyl of at least 0.9 kg/cm of width and a DTA glass transition temperature, T g , below -25° C., (2) cooling the copolyester below its melting temperature, (3) bringing the copolyester into contact with the substrate which is at a temperature below the copolyester melting temperature and while the copolyester is still open, and (4) maintaining the copolyester and the substrate in contact until the copolyester has reverted to its solid, non-bondable state.