COPOLYESTER FILM AND USE AS A HOT MELT ADHESIVE

摘要

A copolyester film is disclosed which comprises a copolyester in which the dicarboxylic acid component comprises 100 to 85 mole percent of terephthalic acid and the diol component comprises 65 to 97 mole percent of 1,4-butanediol and 3 to 35 mole percent of a polyethylene glycol with a molecular weight of 106 to 550. The copolyester has a reduced viscosity in the range of 0.8 to 1.4 dl/g as measured at a concentration of 0.5 g/dl in a 1:1 (by weight) solvent mixture of phenol and tetrachloroethane at 30 DEG C. The copolyester has a main endothermic peak with a peak maximum temperature of 160 DEG C. to 200 DEG C. and at least one subsidiary endothermic peak with a peak maximum temperature of 30 DEG C. to 80 DEG C. in differential scanning calorimetry with the ratio (R) of the area occupying not less than 40 DEG C. in the subsidiary endothermic peak, the main endothermic peak area being within the range of 3 percent to 20 percent. A hot melt adhesive comprising the copolyester film and a method for producing the copolyester film are also disclosed. The hot melt adhesive has a high initial modulus of elasticity at high temperature (30 DEG -50 DEG C.) and features improved processability or workability while retaining the required properties of a hot melt adhesive.