Copolyester hot-melt adhesive and preparation method therefor

A preparation method of a novel copolyester hot-melt adhesive, comprising the steps of:

• 1) selecting raw materials according to preset ratios, wherein the raw materials comprise bisphenol A, maleic acid, terephthalic acid, another dibasic acid, 1,4-butanediol, another dibasic alcohol, catalysts and a stabilizer;
• 2) adding the bisphenol A, the maleic acid and a first one of the catalysts into a reaction kettle with a stirrer, heating to 160° C. to 170° C., and reacting under a pressure of −0.09 MPa to −0.1 MPa for 3.0 hours to obtain a prepolymer;
• 3) adding the prepolymer obtained in step 2), the terephthalic acid, the another dibasic acid, the 1,4-butanediol, the another dibasic alcohol and a second one of the catalysts into a reaction kettle with a stirrer, heating to 190° C. to 200° C. in a nitrogen protective atmosphere, and when water is distilled from the reaction kettle, performing a thermostatic reaction until the distilled water reaches 95% or more of a theoretical distillation amount, thereby finishing an esterification reaction;
• and
• 4) after holding for 15 to 20 minutes, adding the stabilizer, continuing heating to 235° C. to 240° C. to perform a polycondensation reaction and after reaching 80 Pa, continuing polycondensation for 60 to 70 minutes, thereby obtaining the novel copolyester hot-melt adhesive;
• wherein the preset ratios of the raw materials are as follows:
• a mole ratio of bisphenol A to maleic acid is 1.05:1 to 1.15:1;
• a mole ratio of terephthalic acid to another dibasic acid is 1:0.2 to 1:0.5;
• a mole ratio of 1,4-butanediol to another dibasic alcohol is 1:0.2 to 1:0.35;
• a mole ratio of total carboxyls of terephthalic acid and another dibasic acid to total hydroxyls of 1,4-butanediol and another dibasic alcohol is 1:1.5;
• a mole ratio of a total mole number of bisphenol A and maleic acid to a total mole number of terephthalic acid and another dibasic acid is 0.4:1 to 0.6:1;
• the first one of the catalysts and the second one of the catalysts are selected from the group consisting of monobutyl stannic acid and tetrabutyl titanate, and respectively account for 0.03% to 0.06% by mass of the terephthalic acid;
• and
• the stabilizer is triphenyl phosphite which accounts for 0.03% to 0.07% by mass of the terephthalic acid.