吸水樹酯製程之丙烯酸安全性探討

丙烯酸是吸水樹脂製程當中，相當重要的原料；主要原因在於聚丙烯酸鹽類可作為超吸水材料，這是目前生產最多的一類合成超吸水性樹脂，由丙烯酸或其鹽類與具有二官能基的單體共聚而成，這類產品吸水倍率較高，一般均在千倍以上，因此丙烯酸在吸水樹脂工業上佔了很重要地位，使用量相當大。在儲存與應用或純化上會產生自聚行為放出大量的熱產生火災爆炸之危害，主要原因是由於丙烯酸具有共軛雙鍵，化學性質活潑，遇光、熱、過氧化物等容易產生斷鍵而發生聚合；此外，丙烯酸本身有較強的腐蝕性，易燃。受熱易分解產生有毒氣體，因此與丙烯酸相關的職災事件時有所聞。因此，為了加強丙烯酸聚合反應危害的預防，本計畫對丙烯酸進行研究，探討起始劑用量對於丙烯酸聚合反應之溫度變化、探討鋁、鎳、鐵3種金屬粉體對丙烯酸聚合反應之溫度變化、以及抑制劑濃度對丙烯酸聚合反應之影響。實驗發現，100%丙烯酸在溫度達約70℃時，液體開始形成聚丙烯酸，並瞬間產生凝膠效應現象；含有鋁粉及鎳粉的丙烯酸聚合反應，聚合的時間會提前，而含鐵粉的實驗其反應溫度並無明顯提昇；丙烯酸之抑制劑使用濃度200ppm及1,000ppm，對丙烯酸聚合反應之功效未發現有重大差異。因此建議可以使用鐵來做為丙烯酸儲存槽與攪拌槽之材質，且因抑制劑之濃度增加並無顯著功效，無需使用高濃度抑制劑。

Acrylic acid is an important raw material used in absorbent polymer process, because poly acrylic acid could act as a water absorbent. Therefore, acrylic acid and poly acrylic acid play very important roles in the industry. However, there are many acrylic acid related chemical accidents due to its corrosive properties and the nature of self-polymerization, which is an exothermic reaction. In order to prevent acrylic acid related incidents, this project is to study how the different amount of initiator relative to acrylic acid will affect the acrylic acid polymerization process, and the effect of the existence of metal powder such as Al, Ni, Fe, and the increase of inhibitor concentration. The results show that 100% acrylic acid begin to polymerize and the gel effect occurs immediately. Acrylic acid containing Al and Ni will advance the polymerization reaction time while Fe has no significant effect on the reaction. The concentration of the inhibitor at 200ppm and 1,000ppm make no obvious difference on the reaction. Therefore, it is suggested that iron is more suitable as the material for acrylic acid storage tank and stirring tank than Al and Ni. And due to the higher concentration of the inhibitor has no difference than the low concentration one, there is no need to use high concentration of the inhibitor.