| In recent years,with the improvement of residents' income and living environment,outdoor furniture has become a kind of outdoor products with the fastest growth trend,and the consumption market in related fields has developed by leaps and bounds.However,the wood outdoor furniture has higher requirements on the material properties of the base material,so it should.have excellent weather resistance while taking into account the mechanical properties.Among them,the light aging technology is the key technical problem to be solved in the promotion and application of wood outdoor furniture industry.In view of the application defects of outdoor furniture in the outdoor environment,the multi-component UV shielding coating was prepared by compounding the organic ultraviolet absorber benzotriazole(BTZ-1),inorganic ultraviolet absorbent nano zinc oxide(NZnO),hindered amine light stabilizer(HA)and acrylic varnish,and placed in the artificial ultraviolet ring together with the recombined bamboo sheet Accelerated aging treatment was carried out in the environment.The basic parameters of UV absorption region,chroma and glossiness of different kinds of composite coatings before and after aging were analyzed by colorimeter,UV VIS spectrophotometer and Fourier transform attenuated total reflection infrared spectroscopy(FTIR-ATR).At the same time,the comparison method and single factor experiment method were used to study and analyze the influence of HA type and concentration on UV of coating The optimum formula of UV shielding coating for outdoor recombined wood was optimized,and it was applied to the base material of Reconstituted Bamboo outdoor furniture.According to GB/T 33568-2017 test method for artificial aging of exterior bamboo wood coating surface and GB/T 33569-2017 outdoor bamboo wood coating surface aging grade and evaluation method,the application grade of samples was evaluated.The summarizes as follows:(1)The results show that the single component hindered amine light stabilizer does not have obvious UV absorption capacity.Inorganic and organic hybrid two-component coating and multi-component coating with HA have excellent UV absorption performance,which can effectively improve the surface light stability of outdoor recombinant bamboo.(2)HA has less UV absorption,and it can delay the loss of BTZ in the photodegradation process by absorbing free radicals,so as to enhance the photostability of the coating.HA-1(112)has the most obvious effect on improving the photostability of the coating.(3)At low concentration of hindered amine,the UV shielding performance of the coating increases linearly with the concentration of hindered amine.When the concentration of hindered amine is 3%,the composite coating has the best UV shielding ability.When the concentration exceeds 3%,the effect of hindered amine on the improvement of UV shielding ability of coating is not obvious.(4)The optimum formulation of UV shielding coating for outdoor recombinant bamboo was optimized.When the ratio of organic UV shielding agent(BTZ-1),inorganic ultraviolet shielding agent(NZnO)and hindered amine light stabilizer(HA-1)was 2:1:3,the UV shielding coating had good light aging resistance and mechanical properties.After accelerated aging for 300 h,the light inhibition rate of the coating was 81.1%,the hardness was 6h,the film adhesion was grade 2,and the color difference of underlying bamboo was 2.156.(5)The UV shielding coating with the best formula was applied to outdoor Reconstituted Bamboo,and the application grade was evaluated according to the requirements of?GB/T 33568-2017 test method for artificial aging of exterior bamboo wood coating surface?and?GB/T 33569-2017 aging grade and evaluation method of outdoor bamboo wood coating surface?.After accelerated aging for 300 h,the weight loss rate of the sample is 1.456%,the transverse shrinkage rate is 0.61%,the equilibrium contact angle is 59.67°,the discoloration grade is 1,the gloss loss grade is 1,the hardness is 6h,the film adhesion grade is 2,the cracking grade is 0,the peeling grade is 0,the mould growth grade is 0,and the foaming grade is 0.The comprehensive aging grade is 0.Through comparative analysis,the grades of UV shielding coatings for outdoor recombinant bamboo are superior to the national standards. |
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