| Hyperbranched polymer has a highly branched molecular structure containing a large number of active terminal groups. It presents many excellent properties,such as low viscosity, less intermolecular winding, high reactivity and so on. End groups containing a double bond group is an important part of the modified hyperbranched polymer. It can be used as a photocurable coating resin. Hyperbranched technology combined with UV technology to prepare hyperbranched polyurethane acrylate(HPUA) will combine the advantages of the both process. In the synthesis process, polyurethane acrylate(PUA) was firstly synthesized and then it reacts with end groups on hyperbranched polyester.In this paper, pentaerythritol(PE), 2,2- dimethylol propionic acid(DMPA) were as raw materials to synthesize three generations of hyperbranched polyester by one-step method. The structure of products were tested by infrared spectroscopy(FT-IR) and nuclear magnetic resonance(1H NMR,13 C NMR). Its thermal stability were detected by thermal gravimetric analysis(TG). FT-IR results showed that there was a lot of product systems hydroxyl, ester characteristic absorption peak, raw DMPA carbonyl peak at 1689cm-1 disappearing completely synthesized by esterification reaction described HBPE. FT-IR results showed that there were a lot of hydroxyl in product systems. Ester characteristic absorption peak existed. Carbonyl peak of DMPA at 1689cm-1disappeared. As a result, esterification reaction completed and HBPE was synthesized. Results of NMR showed that all of the three generations HBPE have higher degree of branching. They were 0.55,0.49,0.45. Results of TG analysis showed that the product had good thermal stability. When the weight loss was 50%, thermal temperature of the three generations HBPE were 301 ℃, 345 ℃, 346 ℃. The thermal stability improved with the increase of generation.Polyethylene glycol(PEG600), isophorone diisocyanate(IPDI) and hydroxyethyl methacrylate(HEMA) were taken as the main raw materials, synthesized three generations of hyperbranched polyurethane acrylate(HPUA). The appearance, alcohol soluble, solids content, viscosity and some other properties were tested. The results showed that the resin has high transparency, almost no impurities, high solid content, good solubility in alcohol and a lower viscosity.The resulting HPUA mixed with active monomers like 1,6-hexanediol diacrylate(HDDA), three dipropylene glycol diacrylate(TPGDA), trimethylolpropane triacrylate(TMPTA) and photoinitiators 1173-TPO in different mass ratio were made into UV paint formulations. After exposure to UV light, the curing time, glossiness, water absorption, hardness and some other properties of the cured films were measured. The effects of reactive monomer species and content to UV cured film properties were also discussed. The results showed that UV cured films with resin in same generation and same photoinitiator, if the active monomer has tri-functionality, curing time was shorted in 8 seconds. The others with bifunctionality curing time was longer than 8 seconds. As for the UV paint formulations with the same monomer species, the curing time decreased with the increase of monomer amount. However, when the amount of the monomer exceeded 30%, curing time of the coating film became longer. Cured films of all formulations have good glossiness, more than 75 °. Overall, the cured films have low water absorption between 3% to 5.5%. Cured films have high hardness, good adhesion and flexibility, and have certain acid and alkali resistance performance. |
PDF Full Text Request