Preparation Of TiO₂/Benzotriazole Anti-uv Agents And Their Application On PET

Polyethylene terephthalate（PET）is widely used in various fields due to its excellent physical and chemical stabilities,heat resistance and low cost.However,the ultraviolet absorbing ability of the PET itself is insufficient,and the C-O bond in the macromolecule is easily destroyed under the influence of external environment such as ultraviolet rays,heat,oxygen,and water,etc.,resulting in the degradation of macromolecules.Moreover,the lack of reactive groups in the polyester macromolecules makes it difficult to be functionally modified and thus limits its development.In this study,four organic ultraviolet absorbents were synthezied for comparation,and 2-hydroxy-4-（3-methacrylic acid-2-hydroxypropoxy）benzotriazole（BTMA）was selected and hybridized with nano-TiO2 through three different methods to modify PET using a facile pad-dry-cure（PDC）process to prepare UV-resistant and anti-aging PET fabrics.The research work mainly included the following parts.Fistly,four benzotriazole based UV absorbers with double bonds were designed and synthesized for UV-resistant finishing of PET fabrics,whose name were2-hydroxy-4-（3-allyloxy-2-hydroxypropoxy）benzotriazole、2-hydroxy-4-（3-methacrylic acid-2-hydroxypropoxy）benzenetriazole、2-（2-Hydroxy-4-Acryloxyphenyl）-2H-Benzotriazole and 2-（2-Hydroxy-4–Undecenoxyphenyl）-2H-Benzotriazole.For simplicity,the molecules were named in this work as BTAP,BTMA,BTHA and BTHU,respectively.The structures of the monomers were characterized by nuclear magnetic（1H NMR）,infrared spectroscopy（FTIR）and UV-visible spectroscopy（UV-vis）.Scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）and X-ray photoelectron spectroscopy（XPS）were used to characterize the treated fabrics.The results showed that the UV-absorbing monomers were successfully grafted onto the surface of the fabrics.It was found that the UPF values of the fabrics modified with BTAP,BTMA,BTHA and BTHU were（118±3）、（141±2）、（136±3）and（124±2）,respectively,when the monomer concentration was 8 wt%and the initiator concentration to monomer concentration was 2%.The washing stability of the BTMA modified fabrics was superior to others with a UPF retention rate of 70.2%after 50 washing cycles,while the UPF retention rates of fabrics treated BTAP,BTHA and BTHU were 61.9%,58.3%and 58.5%,respectively.Anti-aging experiments showed that after 100 h of UV radiation,the tensile strength retention rates of BTAP,BTMA,BTHA and BTHU modified fabrics were 80.8%,70.4%,67.0%,72.6%in the warp directions,and 70.2%,70.0%,80.0%,78.8%in the weft directions,which were higher than that of untreated fabrics.Secondly,commercial rutile TiO₂ modified with?-methacryloxypropyltrimethoxysilane（KH570）was blended with UV absorbing agent BTMA for the treatment of PET fabrics.SEM,EDS and X-ray diffraction（XRD）were used to characterize the treated fabrics and confirm the successful modification of fabrics.The UPF values of the prepared anti-UV PET fabrics could reach（141±8）when the concentrations of TiO₂-KH570,BTMA,and initiator BPO by mass ratio of monomer were 2 wt%,4 wt%and 2%,respectively.The UPF retention rate could reach 61.7%after being subjected to 50 washing cycles.After 100 h of UV light irradiation,the strength retention rates in the warp and weft directions were 56.4%and 60.8%,respectively,which were almost same as that of untreated fabrics.Thirdly,the composite sol（TiO2/BTMA）was formed by adding UV absorption agent BTMA to TiO₂ gel synthesized from tetraisopropyl titanate as titanium precursor,and used for modification of PET fabrics.SEM,EDS and XRD were used to characterize the treated fabrics and confirm the successful modification of fabrics.After exploreing the finishing process,it was found that the UPF value of treated PET could reach（136±4）when 4 wt%TiO₂ sol and 3 wt%BTMA were applied.It still maintained 66.9%UPF retention rate after 50washing cycles.Moreover,after 100 h of UV radiation,the strength retention rates in the warp and weft directions were 70.3%and 82.3%,respectively,which were higher than that of untreated fabrics.Fourthly,TiO₂ hybrid sol was prepared by mixing tetraethyl orthosilicate as a silicon-based binder with commercial rutile TiO₂.The ultraviolet absorbing agent BTMA was added to the above solution to form coating solution（TiO₂ hybrid sol/BTMA）,and was used for the treatment of PET fabrics.SEM,EDS and XRD were used to characterize the treated fabrics and confirm the successful modification of fabrics.It was found that the UPF value of the modified PET could reach（135±3）when 4 wt%of TiO₂ sol and 2 wt%of BTMA were applied.Up to 58.5%UPF retention ratio was achieved after 50 washing cycles.The strength retention rates of the PET fabrics coated with TiO₂ hybrid sol/BTMA were 65.3%and 66.1%after 100 h of UV light irradiation,which was higher than that of untreated fabrics.The results showed that PET fabrics treated with the above finishing methods could achieve good unti-UV abilities.PET fabrics treated with TiO2/BTMA were more resistant to washing,followed by TiO₂-KH570/BTMA,and then TiO₂ hybrid sol/BTMA.From the perspective of anti-ultraviolet aging effect,the strength losses of TiO₂ hybrid sol/BTMA-treated and TiO₂/BTMA-treated fabrics after UV light irradiation were the less,and TiO2-KH570/BTMA-treated was slightly worse.