Preparation And Membrane Properties Of Epoxy Cyclohexyl Diester Diols Modified WPET

Water soluble polyester（WPET）has the characteristics of environmental protection,low toxicity and excellent performance.It is widely used in coatings,adhesives,inks and other fields.However,its molecular chain contains more hydrophilic groups,which has the problem of poor water resistance and solvent resistance of the membrane.In order to expand the application field of WPET,many scholars at home and abroad have made a lot of research,but most of them modify the polyester by introducing cyclohexyl or epoxy cyclohexyl copolyether,while there are few reports on modifying the polyester with modifiers containing cyclohexyl and aliphatic long chain at the same time.Firstly,diester diols containing both cyclohexyl and aliphatic long chain were prepared from cyclohexene oxide and aliphatic diacid,and their structures were confirmed by FT-IR,¹H NMR and MS;Secondly,the optimum synthesis conditions of WPET were discussed.On this basis,WPET was modified by diester diols,and the effects of different modifier contents on WPET were discussed;Finally,the modified WPET was prepared into the corresponding membrane,the optimal amount of curing agent and the effects of different modifier at different contents on the polyester membrane were discussed.The structures of succinic acid epoxy cyclohexane diester diols（SCHD）,glutaric acid epoxy cyclohexane diester diols（GCHD）and adipic acid epoxy cyclohexane diester diols（ACHD）were characterized by FT-IR,MS and ¹H NMR.The results showed that the structures of the three products were consistent with the expectation.WPET were prepared from p-phthalic acid（PTA）,5-sulfoisophthalic acid monosodium salt（SIPA）,isophthalic acid（IPA）and ethylene glycol（EG）.The optimum dosage of SIPA was15%,and the optimum esterification and polymerization time were 5h and 1.5h respectively;For SCHD modified WPET（SDWPET）,the acid value was 7-16mg KOH·g^-1 and the hydroxyl value was 80-120mg KOH·g^-1.With the increase of SCHD content,the intrinsic viscosity of SDWPET decreased as a whole;For GCHD modified WPET（GDWPET）,the acid value was4-12mg KOH·g^-1 and the hydroxyl value was 90-127mg KOH·g^-1.With the increase of GCHD content,the intrinsic viscosity of GDWPET changed irregularly as a whole;For ACHD modified WPET（ADWPET）,the acid value was 9-14mg KOH·g^-1 and the hydroxyl value was85-110 mg KOH·g^-1.With the increase of ACHD content,the intrinsic viscosity of ADWPET decreased.With the addition of three modifiers,the crystallinity of polyester decreased gradually,and showed the law of color deepening,water solubility first enhanced and then weakened,and the transparency of aqueous solution first improved and then deteriorated.The curing agent was added into WPET aqueous solution to cure the membrane,and the optimum amount of curing agent was 5%.Further prepared with flat and smooth appearance and thickness≤45μm.Modified WPET membrane with gloss of about 100Gu.The results showed that for SDWPET membrane,when the content of SCHD was 2%-4%,the water resistance and chemical resistance of the membrane were the best,when the content of SCHD was 8%,the adhesion of the membrane was the best,which was grade 1,and when the content of SCHD was 4%,the pencil hardness of the film was the best,which was 2H;For GDWPET membrane,when GCHD content is 4%,the water resistance,chemical resistance and the pencil hardness of the membrane were the best.When GCHD content was 2%,the adhesion of the membrane was the best,which was grade 1;For ADWPET membrane,with the increase of ACHD content,the pencil hardness,water resistance,boiling water resistance and chemical resistance of the membrane increased gradually.When the content of ACHD was 6%,the adhesion of the membrane was the best,which was grade 1.When the content of ACHD≥6%,the pencil hardness of the membrane was the best,which was H.The three modifiers had no effect on the impact resistance and alkali resistance of WPET membrane.