熔融複合紡絲口最適化之設計及分析

The Optimization of Die Design and Analysis in Conjugated Spinning

許凱閔(Kai-Min Hsu)

指導教授 ： 蘇淵源

國立臺北科技大學/工程學院/化學工程所/碩士(2006年)

摘要

近年來已發展之纖維種類繁多，改變幾何形狀外觀形成超細纖維，增加柔軟觸感及光澤，甚至賦予吸濕、排汗等新功能，使得複合紡絲成為目前最具有經濟效益和高度精密技術的合成纖維製造方式之一。藉由複合紡絲可得到如天然羊毛般蓬鬆捲曲的效果，而其中融體之間平整的界面更有利於自發捲曲纖維之形成，另外，複合紡絲會因為融體性質差異太大而形成融體彎曲的狗腿現象，造成無法紡絲成型而降低經濟效益，因此，針對材料參數的控制與加工方式的選擇有必要加以研究探討。
本研究使用有限元素法搭配optimesh-3D remeshing之數值技巧，模擬複合纖維紡絲之界面包覆與狗腿現象。本論文將涵蓋兩個部份，第一部份我們針對並列型（side-by-side type）與啞鈴型（dumbbell type）模具，以Constant viscosity、Bird-Carreau、Maxwell、Oldroyd-B及PTT model等本質方程式表示零剪切應變率黏度（η0）、無限剪切應變率黏度（η∞）、自然時間（λn）、鬆弛時間（λ）、高分子溶質與溶液比例（γη）、拉伸效應（ε）及剪稀效應（ξ）對界面包覆平整度與狗腿現象之影響，作一詳盡而完整的分析。研究結果發現，融體由低黏度包覆高黏度，尤其靠近管壁之 對界面平整度有決定性之影響；而減少λ、ε與ξ，增加γη，有助於平整界面的形成，進而減少狗腿現象的產生。
第二部份藉由PET與PBT材料測試數據，選出適當的本質方程式及材料參數後，對於並列型及啞鈴型複合纖維紡絲，探討流體溫度及流量對複合纖維界面包覆率之影響，並與共押出之複合纖維實驗結果做比較。由於本研究所使用的材料高分子彈性效應不顯著，因此，在低彈性狀況下，融體黏度將主導界面包覆與狗腿彎曲的行為。綜合以上討論，我們選用Bird-Carreau model為材料本質方程式，操作溫度PET@290℃與PBT@255℃，複合流量接近50/50的比例，做為實際加工最佳化的條件。

關鍵字

界面包覆 ； 狗腿現象 ； 自發捲曲纖維 ； 並列纖維 ； 啞鈴纖維

並列摘要

In recent years, fibers have developed in various types. In order to increasing the soft sense of touch and gloss, even give the new function of picking the moisture up, exclude the sweat, engineers change the die of geometry to forming micro fiber. The conjugated fiber process is the most economic and high-precision technique to manufacture synthetic fibers at present. The conjugated fiber process is the most economic and high-precision technique to manufacture synthetic fibers at present. It is known that conjugated spinning can gain Self-crimp fibers like natural wool. We are sure that two molten components with smooth interface are helpful to forming of self-crimp fibers. In addition, dog-legging phenomenon will reduce the economic benefits cause too much different property in two molten polymers. For this reason, study of controlling the material parameter and manufacturing process are important.
In this study, we utilizing the finite element approach with optimesh-3D remeshing craftsmanship is applied to investigate the interfacial encapsulation of conjugated fibers and dog-legging phenomena in the spinning process. The thesis consists of two major topics. First, we will express polymeric rheology behavior like zero-shear rate viscosity（η0）, infinite-shear rate viscosity（η∞）, nature time（λn）, relaxation time（λ）,ratio（γη）,elongation effect（ε）,shear-thinning effect（ξ）in Constant viscosity, Bird-Carreau model, Maxwell, Oldroyd-B and PTT model as the differential constitutive equation. After that, our study will examine interfacial encapsulation and performance of dog-legging phenomenon narrowly. From research result, the less viscous melt wraps around the more viscous melt, it is crucial to obtain straight interface depends on . Reducing the λ,ε,ξ,increasing γη are helpful to the formation of straight interface, and then reduce dog-legging phenomenon.
Secondarily, determination of constitutive equation and material parameters with the aid of experimental data of materials of PET and PBT, the influence of temperature, and flow rate of molten polymers in the interfacial encapsulation of side-by-side and dumbbell conjugated fibers is numerically investigated and the results were compared with experimental results of conjugated fibers by coextrusion process. It is due to not clear in elastic property of material. The viscosity of molten polymer is the controlling factor in interfacial encapsulation and dog-legging phenomenon. In order to getting the optimize manufacture condition, we utilize the Bird-Carreau model for constitutive equation with PET@290℃, PBT@255℃, the flow rate ratio is close to 50/50.

並列關鍵字

interfacial encapsulation ； Dog-Legging ； self-crimp fiber ； side-by-side fiber ； dumbbell fiber

參考文獻

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