Study On Synthesis, Modification And UV-Cured Reaction Of Rosin-based Hyperbranched Polyester

Hyperbranched polyester is a hyperbranched polymer with repeating units of ester group and as hydroxyl terminal units. Because of many reactive groups, low viscosity, good solubility, etc, Hyperbranched polyester is suitable as UV-cured oligomer. Hyperbranched polyester can be developed special UV-cured coating with special structure. In this study, rosin-based hyperbranched polyester was synthesized, and applied to the field of UV-cured.A hyperbranched polyester(HBP-1) was prepared by copolycondensation of maleopimaric acid(MPA), trimethylolpropane(TMP), and glycerin. When the mole ratio of alcohol to acid was 3:1, the effects of reaction temperature, material ratios, and catalyst(stannous oxalate) contents on the hyperbranched polyester synthesis were discussed. The results showed that the optimal conditions were as follows: the mole ratio of glycerin to TMP 1∶1, the dosage of catalyst 0.2%, reaction temperature 220 ℃. Under these conditions, the polydispersity index(PDI) was small. The structure and performance of the polyester was characterized by FT-IR, GPC, DSC, and TG. The results showed that HBP-1 contained a large number of ester and hydroxyl groups; the number average molecular weight was 2308; the temperature with thermal weight loss of 50% was 402℃; the glass transition temperature(Tg) was 42.9℃; the intrinsic viscosity was 2.11 mL/g, respectively. The polymer was further modified by methacrylic acid, the obtained hyperbranched polyester contained terminal vinyl groups(VHBP-1). The structure and performance of VHBP-1 was characterized by FT-IR, DSC, and TG. The results showed that VHBP-1 contained terminal vinyl groups; the temperature of 50% thermal weight loss was 379℃; the Tg was-31.78℃; the intrinsic viscosity was 1.1 mL/g, respectively. HBP-1 and VHBP-1 had good solubility. The UV-cured film of VHBP-1 had good flexibility and resistance to water, alcohol, and alkali. And the adhesion force was 1 grade; the impact resistance was over 50 kg/cm; gel rate was 85%; film hardness by pencil was 3H.In the above reaction conditions, the hyperbranched polyester synthesized(HBP-2) by using maleopimaric acid and PEG-400 also was studied. The optimal synthesis process and the effect of materials ratios were discussed. The result showed that the optimal reaction conditions were obtained as follows: 230℃,stannous oxalate as catalyst and the dosage of catalyst was 1.0%. GPC showed that materials ratios of was 1:1.3, the number average molecular weight(Mn) was 2159. The structure and performance of polyester was characterized by FT-IR, DSC and TG. The results showed that: HBP contained large number of ester and hydroxyl groups, the temperature of 50% loss was 415℃,the glass transition temperature(Tg) is-51.74℃. HBP-2 was further modified by Acryloyl Chloride, obtained hyperbranched polyester which contained terminal vinyl group(VHBP-2). The structure and performance of VHBP-2 was characterized by FT-IR,DSC and TG. The results showed that: VHBP-2 contained large number of terminal vinyl groups, the temperature of 50% loss was 418℃,the glass transition temperature(Tg) is-58.55℃.HBP-2 and VHBP-2 had good solubility in weak polar solvent and polar solvent. The UV-cured film had good flexibility, resistance to water, resistance to alcohol and resistance to alkali, The adhesion was 1 grade, the impact resistance> 50 kg/cm, film hardness by pencil is 3H.