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|標題:||Formulation development and trial preparations of crystalline polyurethane adhesives
熱塑性聚胺甲酸酯TPU黏著劑，若具有高度軟鏈段結晶時，比非結晶型的TPU有諸多優點，不但有強的初期接著力，也可提升完成黏合後的接著力，以聚環己內酯多元醇（Polycaprolactone diol；PCL Diol）為主聚酯醇所製成的TPU，在TPU中，除了結晶度之提高外更可帶來相分離之迅速形成，因此，可作成性質極佳之TPU黏膠。為近幾年的發展趨勢。為了順應世界潮流，開發結晶型TPU是國內鞋用黏著劑的主要目標之一。
由分析之資料及可能應用之商業原料，以商業上的聚酯為例，如：聚環己內酯多元醇，依不同軟鏈之起始劑、軟鏈PCL Diol的分子量、硬鏈段與軟鏈段之比，可找出熱性質及結晶型態最接近Pearlstick的比例。以此莫耳數比值為主，再使用不同種類的PCL Diol來製成TPU，比照出最接近Pearlstick物性的PCL Diol分子結構。從儀器的分析中，得知最適當的（BDO/PCL）為0.6而PCL Diol為DEG-3000。由此實驗所得之的配方資訊，使用於雙螺桿反應押出機，以連續式反應程序，可做出非溶劑型之TPU黏著劑。
When thermoplastic polyurethane (TPU) adhesives possess crystalline components as their soft-segments, they generally exhibited superior performances over those without. The formers usually have higher green strengths and provide stronger bonding characteristics after applications. Utilization of polycaprolatone diols (PCL Diols) as the major soft segment component has become one of the most sought-after approach in making adhesive TPUs. Poly-caprolactone diols (PCL Diol) of high molecular weight are crystalline raw materials. TPUs prepared from PCL Diols have been shown to form rapid phase-segregation in the polymer morphology. As a result, the crystalline TPU adhesives possess excellent adhesive properties. Solubility of the TPU in non-toxic solvent such as acetone is also high. In short, crystalline TPUs have many advantages sought in industrial applications such as shoe-making industry.
Our research begins with composition analyses of some commercial crystalline TPU adhesives such as Pearlstick 45-60/18 from Merquinsa and Desmocoll-540 of Bayer. Then we studied their possible raw materials used and determined their crystalline characteristics, molecular weight distributions, solubility and their adhesive performances. From those analyses as our guide, we then developed similar formulations and attempted to prepare TPU adhesives using two processing techniques.
Since the analysis has shown that the major raw materials of TPU adhesives are consisting of methylene diphenyl diisocyanate (MDI), butanediol (BDO), and a polyester diols such as PCL Diols as the major raw materials, we have screened several commercial PCL Diols of different molecular weights and initiators for TPU preparations. In order to match properties of our TPU products with the commercial TPUs, four TPUs with hard to soft ratios of 1.0, 0.8, 0.6 and 0.4 (BDO/PCL Diols) were also prepared. Finally, the thermal and crystalline properties of all these prepared TPU were gathered. Among them, we were able to identify that a (BDO/PCL-3000 diol) ratio of 0.6 would have high similarity to the commercial products. A preliminary continuous preparation of the TPU adhesive using a twin-screw extruder has been tried.
|Appears in Collections:||化學工程學系所|
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