本研究之最終目標在製備高折射率奈米複合樹脂透明厚膜，其中複合膜中有機材料的部分選用作為LED封裝材料的環氧樹酯ERL-4221(折射率1.5)。無機材料的部份則是選用奈米氧化鈦與奈米氧化鋯，這兩種材料的折射率都在2以上(anatase 相氧化鈦折射率為2.3，氧化鋯則為2.1)，是常見金屬氧化物中折射率較高的，適合被用作提升有機材料的折射率。 初期首要工作為合成高分散性奈米氧化鈦與奈米氧化鋯結晶。為了使奈米複合樹脂厚膜具備透明性及高折射率，因此勢必控制奈米粒子的分散性及結晶大小。我們針對奈米結晶合成過程中的前驅物水解控制、中和pH 及水熱條件(pH、溫度及時間)等作探討，尋找出適合本研究之最終目標的高分散性奈米氧化鈦與奈米氧化鋯結晶之最佳合成條件。 得到高分散性奈米氧化鈦與奈米氧化鋯結晶之後，我們另外研究了TiO2-ZrO2 混合氧化物的合成，試圖瞭解奈米結晶的導入是否具有優勢。最後發現控制鈦源和鋯源的混合方式，經過600℃鍛燒後可以得到ZrTiO4 奈米結晶。 製備奈米複合樹脂必須使奈米結晶與環氧樹酯ERL-4221 均勻混摻或者是彼此產生化學鍵結進而完成交聯硬化，兩者都必須將奈米結晶經過表面改質，方可達成。我們嘗試了油酸、有機胺與矽烷的表面改質，將奈米氧化鈦與氧化鋯結晶分散在有機溶劑中，使其可以與環氧樹酯ERL-4221 均勻混摻。 最後我們選擇將水相分散的奈米氧化鈦與奈米氧化鋯結晶，經過 MPTMS/GPTMS 矽烷改質後，分散在醋酸乙酯中，與環氧樹酯ERL-4221 混摻後，以刮刀塗佈法鍍膜後經過加熱硬化，可以得到奈米TiO2/Epoxy 與ZrO2/Epoxy複合透明厚膜。其中氧化鋯(氧化鈦)含量提高到~45 wt%，折射率可以提升到1.63(1.7)，膜厚2-13 μm (8-35 μm)，而且厚膜之光穿透度在波長600nm 位置時仍有90%以上。 The objective of this research is the preparation of high refractive index transparent nanocomposite thick film. The organic matrix of nanocomposite, epoxy resin ERL-4221 (refractive index is 1.5) is used as an encapsulant of LED. The inorganic material is selected nano-TiO2 and nano-ZrO2 which the refractive index of the two materials are higher than 2 (the refractive index of anatase-TiO2 is 2.3,compared to 2.1 for ZrO2) to enhance the refractive index of organic materials. The primary work is the synthesis of highly dispersed TiO2 and ZrO2 nanoparticles. For high refractive index transparent nanocomposite, it is necessary to control the dispersity and crystal size of TiO2 and ZrO2. The influences of hydrolysis of precursors, pH value of neutralization and hydrothermal condition(pH, temp. and time) in the synthesis process of highly dispersed TiO2 and ZrO2 nanoparticles were discussed. In addition, the preparation of TiO2-ZrO2 mixed oxide was studied. The interesting was whether the advantages of TiO2 and ZrO2 nanocrystals imported for preparation of ZrTiO4 nanocrystal. ZrTiO4 nanocrystal was prepared with the coprecipitation of methacrylic acid-TiCl4 and methacrylic acid-ZrOCl2 by calcination at 600℃. To disperse nanoparticles and epoxy resin in organic solvent, surface modification of the nanoparticles is pivotal. Surface modification of nanoparticles with oleic acid (sodium oleate), n-hexylamine (dodecylamine) or silane (3-methacryloyloxy propyl trimethoxysilane and 3-glycidoxy propyl trimethoxysilane) allowed nanoparticles to be dispersed in n-hexane, chloroform and ethylacetate. The MPTMS&GPTMS-modified TiO2 and ZrO2 dispersions in ethylacetate were blended with epoxy resin ERL-4221 and curing agent. The TiO2/epoxy and ZrO2/epoxy nanocomposite thick film was prepared with MPTMS&GPTMS modified nanoparticles and epoxy resin ERL-4221 which were dispersed in ethylacetate by blade-coating and thermal curing. The thickness of TiO2/epoxy and ZrO2/epoxy nanocomposite thick film which contained 15-45 wt% TiO2 or ZrO2 was 2-13 μm and 8-35 μm individually. The refractive index of TiO2/epoxy and ZrO2/epoxy nanocomposite thick film was up to 1.7 and 1.63 respectively. The optical transmittance of TiO2/epoxy and ZrO2/epoxy nanocomposite thick film was higher than 80% at wavelength of 600 nm.
