紫外光可硬化聚丙烯酸酯感壓膠製備與性質之研究

本研究合成出由高分子聚合物、稀釋劑與交聯劑所構成，具有半互穿高分子網狀結構的紫外光可硬化聚丙烯酸酯感壓膠，並藉由改變其組成探討各成分對感壓膠黏著性質、熱性質、光學性質與黏彈性質的影響。首先聚合出以具有低玻璃轉化溫度(Tg)的丙烯酸-2-乙基己酯為主的高分子聚合物，並藉由硬單體甲基丙烯酸甲酯與乙酸乙烯酯、雙官能基單體乙二醇二丙烯酸酯的引入改變高分子聚合物的性質。結果顯示，Tg隨著硬單體添加量上升，分子量受到產物組成影響而有不同的分佈情形。高分子聚合物分子量大幅地影響感壓膠的黏著物性：隨著分子量增加，感壓膠的剪切強度提升，初期黏著力下降，剝離測試的結果由部分內聚破壞轉為黏著失效。交聯劑使用三羥甲基丙烷三丙烯酸酯(TMPTA)與乙氧基化三羥甲基丙烷三丙烯酸酯(TMPEOTA)作比較，後者分子鏈較柔軟，顯示出較高的初期黏著力與剝離強度，但剪切強度較差。隨著交聯劑添加量增加，兩系統都顯示出剪切強度提升、初期黏著力和剝離強度下降的趨勢。增加稀釋劑EHA添加比例對交聯結構的形成略有改善，但整體而言影響不大。本研究引用黏彈視窗的概念，探討感壓膠黏彈性質與黏著物性間的關聯，並觀察組成改變造成黏彈視窗的移動情形。結果顯示，本研究所合成得到的感壓膠各成分間相容性極佳，在可見光區間皆有極高的穿透度。產物T1-5與TE5表現出與市售商品相似的黏著物性，具有應用在顯示產業上的潛力。

關鍵字

紫外光可硬化；聚丙烯酸酯感壓膠；高透光度；半互穿高分子網狀結構；黏彈視窗

並列摘要

A series of optical clear UV-curable acrylic pressure-sensitive adhesives (PSAs) were proposed and synthesized. The optical clear UV-curable PSAs were obtained from mixing low glass transmission temperature (Tg) polymers and reactive diluents together. At first, different low Tg polymers were polymerized through solution polymerization of different composition of acrylate monomers (2-ethylhexyl acrylate (EHA), methyl methacrylate (MMA), vinyl acetate (VAc) and ethylene glycol diacrylate (EGDA)). These above-mentioned EHA-based copolymers were then mixed-up with several diluents (EHA, trimethylolpropane triacrylate (TMPTA) and ethoxylated trimethylolpropane triacrylate (TMPEOTA)) to construct the optical clear UV-curable PSAs. After UV-light radiation, the PSAs were photo-polymerized to form semi-interpenetrating (semi-IPN) polymer networks. The adhesion properties of the PSAs were characterized via measurements of tack, peel adhesion and shear strength. The results exhibit the shear strength increases with increasing crosslinking density and the molecular weight of obtained polymers, whereas the tack properties showing the opposite trends. The results of failure modes from peel tests were found to be strongly dependent on the molecular weight of obtained polymers, the failure mode varying from cohesive failure to adhesive failure was observed with increasing molecular weight of polymers. The concept of viscoelastic window (VW) was introduced and adopted to categorize synthesis of PSAs and to investigate the correlation between viscoelastic properties and adhesion performance. The presence of EGDA and MMA in the EHA-based copolymers was found to affect crosslinking density and the molecular weight of obtained polymers which are important parameters of the PSAs formulation. With different composition of the PSAs, their locations in the VW were discussed to demonstrate the different adhesion properties. The T1-5 and TE5 PSAs were found to exhibit comparable adhesion properties with commercial products and high transparent in the visible light region. These results indicate that T1-5 and TE5 PSAs were promising material for utilization as optical clear UV-curable materials.