Synthesis And Performance Of UV-curable Resin Based On HTPB For Wood Coatings

In recent years,with the improvement of environmental protection regulations and people’s awareness of environmental protection,the environmental requirements of furniture products have gradually increased,which has promoted the development of environmentally friendly coatings.As a typical representative of energy-saving and environment-friendly coatings,UV-curable coatings have attracted widespread attention because of their"5E"characteristics,such as high efficiency,enabling,economy,energy saving and environmental protection.Curing speed is an important indicator in the process of coating curing film formation,and a faster light curing speed can effectively improve the film formation rate of UV-curable coatings on substrates.In addition,as the external protective layer of the coating will inevitably suffer external damage during service and affect the service life,so it is important to develop coatings with fast light curing and self-healing function.As the main component of the coating,the UV-curable resin plays a decisive role in the performance of the coating.In response to the above problems,this paper prepares a resin with rapidly UVcurable and self-healing ability by designing and modifying the structure of hydroxyl-terminated polybutadiene(HTPB)as a raw material.Firstly,a fast UV-curable resin was designed by selecting pentaerythritol triacrylate(PETA),oxalyl chloride(COCl),and hydroxyl-terminated polybutadiene liquid rubber(HTPB)as raw materials.The resin used highly flexible polybutadiene as the molecular backbone,PETA containing several photosensitive groups as the terminal group of the resin,and COCl,which does not produce hard segments,as a bridge to connect the HTPB and PETA by esterification reactions.By changing the molar ratio of PETA/HTPB in the formulation,a series of UV-curable resins were synthesized.The resins have rapidly UV-curable speed that can maintain the shape within 1s,basically cured within 5s.The Young’s modulus of cured samples of resins is much lower than that of rubber and polyimide,and their maximum Young’s modulus is 11.4±0.8MPa,which is harder than artery but softer than the skin,and the minimum is 1.32±0.1MPa,which is like cartilage.The tensile strength of the fast UV-curable resin increased from 0.27MPa to 0.9MPa with the increase of PETA content.In addition,the UV-curable resin has a T_g of about-60°C and a thermal decomposition temperature of about450°C,giving it a wide range of applications.The resin also has the ability of 3D printing,and the soft sensors were prepared by imitating embedded 3D printing method,and the prepared sensors can detect the basic motion of human body.In addition,the pencil hardness of the coating prepared with it as the main component is small,the gloss is between 60-70°,the adhesion grade reaches grade II,and the resistance to toluene wipe is more than 150 times.In addition,by introducing disulfide bonds into the main chain of HTPB molecules,a UV-curable resin with good healing ability were designed and synthesized.Replacing COCl with isophorone diisocyanate(IPDI)as a chain extender and introducing bis(2-hydroxyethyl)disulfide(HEDS)into the molecular backbone to synthesize a UV-curable resin with self-healing ability.The effect of disulfide bond content on the self-healing ability was investigated by varying the amount of HEDS addition.The results demonstrated that the tensile strength of the self-healing UV-curable resin was highest at 3.14MPa,and decreased slightly with increasing disulfide bond content.The T_gof the self-healing UV-curable resin was found to be less than 65°C by DMA and DSC tests.Heated at 85°C for 8h,the healing efficiency could reach 89.8%.Two scratches were made on the resin surface with a razor blade,and the scratches disappeared almost completely after healed.In addition,the self-healing UV-curable resin has good transparency,and its light transmission rate is about 80%.The pencil hardness of the coatings prepared with self-healing resin as the main component is 6H grade,the glossiness is between 20-45°,the adhesion grade is 1,and solvent wipe resistance(ethanol and acetone)can reach more than 500 times.In this thesis,UV-curable resins with fast light-curing and self-healing capabilities were successfully prepared.These UV-curable resins are characterized by low cost and good adhesion,and have great potential for application in UV-curable wood coatings and 3D printing.