| Summary: | 博士 === 逢甲大學 === 化學工程學所 === 100 === The purpose of this study was to modify the polymerization of Polymethylmethacrylate (PMMA) pressure-sensitive adhesives, in order to improve the heat and weathering resistance properties of acrylic adhesives. There are two methods to modify the polymerization of Polymethylmethacrylate (PMMA) pressure-sensitive adhesives. The one method is chemical modify, and the other one is physical modify. First, for chemical modify, a sol-gel method was adopted to hydrolyze the silicon precursor tetraethoxysilan (TEOS) so as to obtain silica with an -OH functional group. This was further confirmed by a Fourier Transform Infrared Spectrophotometer (FT-IR). The polymerization of acrylic pressure-sensitive adhesives was then carried out, in which hydrolyzed silica acid-alcohol was added into the reactor in order to complete the modification of adhesives. An FT-IR was used to confirm that the adhesives contained an Si-O-Si functional group, while SEM’s observation on the coatings of pressure-sensitive adhesives showed satisfactory dispersion of silica. Coatings of acrylic pressure-sensitive adhesives containing SiO2 were used to produce label, and were tested for heat and weathering resistance, along with other physical properties. The results showed that the heat resistance properties of pressure-sensitive adhesives containing SiO2 were significantly improved. In terms of adhesion, after extended UV irradiation, it was proved that pressure-sensitive adhesives containing SiO2 could prolong the recession of physical properties under severe UV conditions. The resistance to heat could be improved to more than 260℃, which is better than regular acrylic pressure-sensitive adhesives. The other study is to add hydrolysis of the silica in the polymerization of latex acrylic pressure-sensitive adhesive, The resistance to heat could be improved to more than 120℃. Adding nano-silica for the aggregation of latex acrylic adhesives strength and temperature performance results more apparent. These results can provide assistance in the improvement of the physical properties of acrylic pressure-sensitive adhesives in the future.
For the physical modify, The study of surface chemical modification of SiO2 nanoparticles by silane coupling agent and their effect on the thermal and physical properties of acrylic pressure-sensitive adhesive (PSA) was discussed in this work. Aminopropyl triethoxysilane was chosen as the coupling agent and was first hydrolyzed and then condensation with the surface －OH group of SiO2 to modify the nanoparticles.The surface chemical modification of SiO2 nanoparticles was confirmed using the FT-IR spectroscopy. The hydrophobicity of these silane-modified SiO2 and their compatibility with the PSA were further confirmed by the good particle dispersion result from the SEM analysis. After applying the SiO2-modified PSA to bike label, thermal and UV stability tests were conducted to evaluate the doping effect of nanoparticles on the performance of acrylic PSA. It was found that both thermal and UV stability of PSA were significantly improved with the addition of SiO2 nanoparticles. The effect of this improvement was highly significant especially for high molecular weight acrylic PSA. Though the adhesion strength of PSA was found to decrease slightly with the addition of SiO2 nanoparticles, the UV resistance effect was highly improved especially for low molecular weight acrylic PSA. The SiO2-modified PSA has been found in this work to be a promising way to improve the performance of acrylic PSA.
Key word:SiO2, Sol-gel, Polymerization, acrylic pressure-sensitive adhesives, SiO2 nanoparticles
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