Preparation And Application Of Ultra - Branched Polyurethane / Acrylate UV Light Curing Resin

Hyperbranched polymers own unique properties for its highly branched molecular structure, such as low viscosity, high solubility, small molecular twining, especially those large amounts of active terminal groups, chemical modification of those terminal groups can help to change the physical and chemical properties of hyperbranched polymers and do some functions control. Double bond-containing terminal groups is an important part of modification hyperbranched polymers, which not only contain the advantages of hyperbranched polymers, it can also be UV curved and suitable for the use as a photo-curable coating resin.Hyperbranched polyurethane acrylate can be prepared by double monomer direct synthesis method, hyperbranched polyester modification and hyperbranched polyurethanes modification method, it has the features of hyperbranched polymers and urethane acrylate resin, showing excellent overall performance. However, the research about chain extender introduced into hyperbranched polyurethane inner core to prepare hyperbranched polyurethane acrylate is still less.Hyperbranched polyurethanes modification method was employed in this paper, chain extender was introduced in the synthesis process to prepare multi-generation and system hydroxyl-terminated hyperbranched polyurethanes, its structure and properties were studied; then hydroxyethyl acrylate was introduced into hyperbranched polyurethanes to prepare UV-curable hyperbranched urethane acrylate HPUA, groups of structure characterization and film testing were employed to inquiry the relation between its molecular structure and coating performance, at last, HPUA was added into common light-cured resin to prepare cured film and study the coating properties.The main content of this paper included four points:1. Synthesis of hyperbranched polyurethanesIsophorone diisocyanate (IPDI) and neopentyl glycol (NPG) were used to prepare A2reaction intermediate, then A2intermediate and diethanolamine (DEOA) reacted to get AB2intermediate, finally AB2monomer executed self-condensation reaction to prepare multi-generation terminal hypredroxyl hyperbranched polyurethane HPU-NPG, which contains chain extender NPG, HPU-NPG was white powder. As a reference, HPU-0, no chain extender introduction, was also prepared.2. Structure and properties studies of HPUFourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TG), differential scanning calorimetry (DSC) and thermal gravimetric analysis-Fourier transform infrared spectroscopy (TG-IR) were used to do the analysis characterization. FTIR showed that the product owned amounts of hydroxyl (OH), isocyanate (NCO) was reacted completely, while urethane linkages (NHCOO) appeared; TG analysis explained the different generation HPU all had three thermal decomposition temperature sections, enjoyed similar thermal degradation process; DSC indicated that the glass transition temperature (Tg) of the same system HPU increased with the increase of generation. TG-IR showed that the three segments thermal degradation:dissociate of alcohols, urethane bond and ureido groups bond, the degradation under air was faster than that under nitrogen atmosphere.3. Synthesis of hyperbranched urethane acrylateIsophorone diisocyanate and hydroxyethyl acrylate were used to prepare semi-addut IPDI-HEA, then IPDI-HEA was used to modify multi-generation and system HPU to prepare hyperbranched polyurethane acrylate HPUA, the reaction product HPUA was white powder.4. Structure and properties studies of HPUAFT-IR, NMR, TG, DSC and FTIR-TG were used to study the molecule structure and thermal performance of HPUA, FTIR and NMR analysis showed that hydroxyethyl acrylate was grafted into HPUA and HPUA was hyperbranched structure; TG demonstrated that multi-generation HPUA had three thermal decomposition temperature sections, enjoyed similar thermal degradation process; DSC indicated that the glass transition temperature (Tg) of HPUA was significantly reduced for the introduction of hydroxyethyl acrylate. TG-IR showed that the three segments thermal degradation of HPUA were:dissociate of hydroxyethyl acrylate, urethane bond and ureido groups bond, the degradation under air was faster than that under nitrogen; then HPUA-NPG was added into common light-cured resin in different ratio(mass ratio were2%、4%、6%、8%、10%respectively) to prepare curved coating and study the effect of the addition amount to the coating performance, the test results showed that:the addition of HPUA didn’t change the thermal stability of the cured film, and the mechanical properties improved to some extent; the test of different generation product demonstrated that:at the same HPUA addition amount, the pendulum hardness slightly reduced with the improvement of generation, such as10wt%composite of four generation were0.53,0.50,0.46and0.43respectively; the adhesion improved a little, such as6wt%composite of four generation were4,4,4and3; the flexibility were≤2mm in the amount of10wt%; the impact strength improved with generation, such as10wt%composite of four generation were40,45,47and50respectively.