以無皂乳化聚合法合成具消光特性之複合乳膠顆粒及其應用

Abstract

目前在塗料界被廣泛作為消光漆中提供消光特性的材料，通常是利用添加改質過的二氧化矽顆粒於亮光漆中，這種技術具有低價與高度普遍性的優勢，然而在使用二氧化矽消光材料最常碰到的問題是其塗膜極差的耐刮性質，這種問題主要源自於在製作消光漆時，將二氧化矽消光顆粒與亮光漆相混時，其耐刮性極差的現象可能源起於無機的二氧化矽顆粒與有機的亮光漆乳膠顆粒之間不相容，我們嘗試合成一個新穎的核殼型消光共聚高分子奈米顆粒以改善消光漆顆粒與亮光漆乳膠顆粒間的相容性。 在本研究中，核殼型消光乳膠顆粒是利用無皂乳化聚合法合成核心，接著再利用溶膠-凝膠法製作外殼，我們嘗試改變以下的實驗條件:單體的比例、矽烷的種類、矽烷的添加量、pH值以及合成的製程來合成消光乳膠顆粒，為了製作不同配方的消光漆，在不同的條件下合成的消光乳膠顆粒與亮光漆混合。對於添加含氟矽烷的配方而言，我們發現在合成中加入越多量的含氟矽烷將造成塗膜較低的60度光澤度數值與更好的膜性質，這個現象可能是源起於氟原子的超疏水性，加入最多量含氟矽烷的F4配方具有最好的消光效果與膜的性質，此現象可以由F4配方所成的膜的SEM影像解釋。同樣地，加入含長碳鏈矽烷的配方亦與含氟矽烷的配方有相同的趨勢，即添加越多量的矽烷將有越好的消光效果。含長碳鏈矽烷的配方與含氟矽烷的配方唯一不同的地方在於pH值對於長碳鏈矽烷的溶膠-凝膠反應有重大影響，但對含氟矽烷的影響卻不顯著。為了節省時間與金錢成本，我們嘗試使用連續製程並以遠比含氟矽烷花費低的OTS矽烷來取代先前使用的矽烷，最終我們開發出一個F1配方，其60度光澤度幾乎可達到市售消光漆的標準並且其成所成的膜具有良好的性質，F1配方所成的膜的SEM圖能夠解釋其良好的消光效果。因D1與F4配方具有良好的消光效果與膜的性質，我們建議以D5與F1配方作為市售消光漆的配方。

The widely-used matting agents for commercial low-gloss paint sold in the paint industry are usually modified silica particles because of their low price and availability. Nevertheless, one of the commonly encountered problems for the use of silica matting agent in low-gloss paints is the poor resistance against scratch for the coated film. To test this theory, I blended the silica matting agents into a glossy paint latex solution to make a low-gloss paint formulation to find that the poor scratch-resistance of the coated film resulted from the incompatibility of the inorganic silica particles and the organic glossy paint latex particles in the solution. To solve the encountered problem, I propose to synthesize a new type of core-shell hybrid nanoparticles to be used as the low-gloss matting agent and to improve the compatibility of the matting particles and the glossy latex matrices. In this thesis, different core-shell low-gloss matting latex particles were synthesized via soap-free emulsion polymerization to first obtain the core of the hybrid particles. Afterwards, a sol gel method was carried out to synthesize SiO2 with different surface modification silane coupling agents as the shell layer for the hybrid particles. To synthesize the low-gloss matting latex particles, the following experimental conditions were varied, such as adjusting monomer ratio, silane types, the amount of silane added, and the pH of solution during the synthetic process. The resulting core-shell hybrid latex particles synthesized under different conditions were blended into a glossy paint formulation to make low-gloss matting paints with different formulations. For the formulations with a fluorinated silane coupling agent (F-silane), it was found that more F-silane added in the synthesis results in a lower gloss value in the 60o transparency test of the coated film and a better film formation property, which may be attributed to the super hydrophobicity of the surface coating with fluorinated compounds. The formulation D5 with highest amount of F-silane added is the formulation shows the best film properties and low-gloss matting effect. This result can be explained by examining the SEM image of the film coated from the D5 formuation. Similarly, the formulations with a long carbon chain silane added follow the same trend that more silane addition led to better matting effect of the coated films. In order to reduce the manufacturing time and cost, an improved continuous synthesis process was developed and a replacement lower cost silanes (OTS-silane) was synergistically used. Finally, I developed a F1 formulation from which a coated film was made to give relatively low transparency in the 60o gloss measurement, which is close to the criterion to be used as a commercial low-gloss matting paint that passed all the film property tests. The improved matting effect for the coated film with F1 formulation can be explained by examining its SEM images. Consequently, I can suggest two formulations of D5 and F1 to be used to compete with current commercially-available low-gloss matting paint since both of them possess great low-gloss matting effect and superior film property.