半批式乳化聚合製備核殼型壓克力感壓膠

Abstract

現今乳化聚合漸漸取代傳統使用之溶劑聚合，使產品達到無揮發性有機化合物 (volatile organic compounds, VOCs) 綠色環保的概念，因此本論文以半批式乳化聚合之方式製備核殼式 (core-shell) 壓克力系感壓膠 (pressure sensitive adhesives, PSA) 。 本實驗以core-shell顆粒為主軸，以半批式進料製備出固含量為41 wt%的乳液，實驗可分為兩個階段，第一階段為core乳液之製備，以批式反應製備出150-200 nm之顆粒當成種子乳液，接著以半批式進料，製備出粒徑分佈窄且平均粒徑大小約為350 nm之core-shell型態顆粒。 探討之變因有三個，分別為改變core固含量、core顆粒之單體比例及第二階段使用不同製程及配方所造成之差異，第二階段之製程從水相、油相混合後進料改為在低轉化率時水相、油相分開進料及減少起始劑用量，發現當改變製程可大幅減少乳液中新成核的現象，並均勻長成core-shell型態之顆粒，且對乳液顆粒進行動力學分析，算乳液中之總顆粒數，由顆粒數看乳液隨時間產生成核及凝聚的量，並觀察到乳液中之成核和凝聚會接連發生。 而本論文也探討當乳液乾燥成膜後，其機械性質及凝膠分率之影響，並對於感壓膠常用之滾球初黏力 (BT test) 、鋼板黏著力 (SS test) 和保持力 (HP test) 測試下發現，此感壓膠具有優異的黏著力和內聚力表現。

Nowadays, emulsion polymerization gradually replaces the traditional solution polymerization. The final product which reduces the use of volatile organic compounds is environmentally friendly. The thesis shows the semi-batch emulsion polymerization of core-shell acrylic latex particles for pressure-sensitive adhesives. In this experiment, the solid content is 41wt% for the core-shell particles using semi-batch feeding. The experiment is divided into two stages. The first stage is the preparation of core particles about 150-200 nm by the batch reaction. The particles are used as seed emulsion, following by semi-batch feeding to prepare core-shell type particles having a monodisperse particle and size about 350 nm. There are three variables for the study. First is the solid content of core particles, the second is the monomer ratio of the core particles and the third is the feeding step using different processes and formulations. The second stage process is changed from the aqueous phase and the oil phase feed at the same time to separate feeding when the low conversion and the amount of the initiator is reduced. It is found that when the process is changed, the phenomenon of new nucleation in the emulsion greatly reduced, and the core-shell particles are uniformly grown. Then, we use the dynamic light scattering data to calculate the total number of particles in the emulsion. It is observed that nucleation and coagulation in the emulsion occurred in succession. This thesis discusses the effects of mechanical properties and gel fraction when the emulsion is dried. Moreover, we use rolling ball test (BT test), peel strength (SS test) and retention force (HP test) for pressure sensitive adhesives. The data shows that the pressure sensitive adhesive has excellent adhesion and cohesion performance.