Preparation and Properties of Water Soluble Copolyester for Coating Solution
In this experiment,water soluble polyester(WSPET)was synthesized by two-step esterification with terephthalic acid(PTA),isophthalic acid(IPA),sodium phthalic acid-5-sulfonate(5-SSIPA),ethylene glycol(EG)and dihydroxymethyl propionic acid(DMPA)as raw materials,tetrabutyl titanate as catalyst.BOPET/WSPET composite membrane was prepared by emulsion crosslinking with hexa(methoxymethyl)melamine(HMMM)as crosslinking agent by the coating method.The effects of different amounts of 5-SSIPA and DMPA on the contact angle,thermal properties,boiling resistance,optical properties and physical properties of the samples were investigated.The result shows that with the increase of the amount of 5-SSIPA,the hydrophilicity of the water-soluble polyester increases,the glass transition temperature increases,and the boiling resistance decreases.With the increase of the amount of DMPA,the hydrophilicity of the water-soluble polyester is enhanced,the boiling resistance is enhanced,and the pencil hardness and adhesion of the composite membrane are significantly improved,but the flexibility is reduced.When the addition amount of 5-SSIPA is 50%(relative to IPA mole ratio)and the addition amount of DMPA is 250%(relative to IPA mole ratio),the comprehensive performance of the sample is the best.