【作者】 张静；

【导师】 王善元；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2006， 博士

【摘要】 二醋酯长丝在上世纪20年代就实现了工业化，是纤维素纤维的主要品种之一。在过去相当长的时期内，二醋酯长丝主要用于高档服装的里料。到20世纪末，二醋酯长丝的应用领域发生了明显变化，形成了服装面料、里料和服饰等三分天下的格局。但是，二醋酯纤维的生产技术至今仍由为数不多的几家跨国公司所垄断，我国对二醋酯长丝的纺丝及产品开发等原创性工作的报道几乎为空白。本文首先对二醋酯长丝的纺丝及其结构性能进行研究，并尝试开发二醋酯／合纤长丝复合空变纱，最后着重考察了二醋酯长丝的空变短纤化工艺及其形态特征和评价。本文以开发纺织用二醋酯长丝为目的，借鉴烟用二醋酸丝束纺丝设备和工艺，纺制二醋酯长丝，分析了纺丝工艺参数对二醋酯纤维物理性能的影响。当其它纺丝工艺参数一致时，采用较高的纺丝液浓度，纤维强度较高；纺丝液浓度相同时，纤维强度随残余溶剂量的升高而增大；热空气温度升高时，纤维质量比电阻减小；纺丝液浓度降低，纤维质量比电阻增大。采用TG、DSC、X—射线衍射和扫描电境等测试技术对二醋酯纤维的热性能、结晶、取向和形态等结构特性进行测试。结果表明二醋酯纤维在220～260℃这个温度范围内发生分解，DSC谱图上有两个特征熔融峰，说明这种纤维可能存在两种晶型结构；纤维的结晶度和取向度都很低，因此强度和耐磨性较差；纤维横截面呈不规则方齿形，侧面有沟槽。针对纤维强度偏低的特点，采用干热和湿热两种条件来处理(松弛和张紧状态)二醋酯长丝，研究了处理温度、时间和张力对纤维强伸性能的影响。经松弛干热处理后，纤维强伸性能变化不显著；经张紧干热处理后，纤维强伸性能发生较大变化；将张紧干热处理和湿热松弛处理结合应用，纤维强伸性能变化更明显。其次，本文将空气变形加工应用于二醋酯长丝，分析了成纱及其织物的性能特点。发现：二醋酯长丝的空气变形加工不能应用较高的喷嘴压力，否则变形加工不能顺利进行；二醋酯空变纱的强度和断裂伸长率很低，后续加工的技术要求较高。二醋酯面料的拉伸强力和撕裂强力较低、耐磨性能较差，但抗起毛起球性能良好，且光泽柔和，手感柔软。鉴于上述结果，根据优势互补、取长补短的设计原则，本文将二醋酯长丝与涤纶、锦纶等合纤长丝复合，开发皮芯型二醋酯／合纤长丝复合空变纱，研究了芯丝特性对复合空变纱性能的影响，同时分析了二醋酯／涤纶复合空变纱的形态结构特征。实验结果显示：合纤长丝的引入使得二醋酯长丝的空气变形加工可以应用较高的喷嘴压力，因此变形效果理想，而且工艺过程稳定；皮芯型二醋酯／合纤长丝复合空变纱的沸水收缩率和强伸性能主要由芯丝决定；三维视频显微照片显示二醋酯／涤纶复合空变纱的表面出现一些二醋酯纤维断头，说明二醋酯长丝在空变纱表面形成丝圈丝弧的同时发生了短纤化效应；皮丝超喂率较小时，成纱丝圈丝弧和毛羽个数随高度增加不断减少，基本呈指数分布，主要集中在0.5mm处；随皮丝超喂率增加，丝圈丝弧和毛羽的高度逐渐呈二次曲线分布，主要集中在0.5～1.5mm高度范围。关于二醋酯长丝空变短纤化加工工艺的研究，本文分析了单一工艺参数和Texspun装置对短纤化程度的影响，比较了不同皮丝的空变短纤化现象，并通过正交试验对二醋酯长丝的短纤化效应以及成纱性能进行综合优化。皮丝超喂率对毛羽数的影响没有明显规律；芯丝超喂率提高，毛羽数略有减少；喷嘴压力提高，毛羽数稍稍增加；变形速度加快，毛羽数趋于减少；欠喂率提高，毛羽数的变化不明显；采用皮丝给湿时，毛羽数最多。总体看，在单一空气变形工艺条件下，二醋酯长丝的空变短纤化效应不够突出，即复合空变纱表面的二醋酯纤维毛羽数量增加较小。经Texspun装置加工后，成纱毛羽数和圈弧数都有增加，其中毛羽数的增加幅度较圈弧数大，但成纱强度和丝圈稳定性不受影响。喂入皮纱不同，圈弧数和毛羽数增加的幅度不同。喂入皮丝为涤纶或锦纶长丝时，毛羽数和圈弧数的增加幅度较小；皮纱为二醋酯长丝时，毛羽数或圈弧数的增加幅度较大，常规空变纱和Texspun纱的毛羽数均为最大。正交试验分析表明，对毛羽数影响最显著的因素是变形速度，其次是喷嘴压力；芯丝超喂率是影响成纱强度和不稳定度的主要因素；皮丝超喂率则是纱芯膨松度的主要影响因素。关于二醋酯长丝空变短纤化特征及评价的研究，本文首先对二醋酯长丝的空变短纤化形态与已有文献报道的二醋酯纤维断裂特征以及二醋酯纤维在不同拉伸速度下的拉伸断裂形态进行比较研究，然后结合空气变形加工中的作用力分析，探讨了二醋酯长丝空变短纤化现象的发生机理，最后以具有不同短纤化程度的二醋酯／涤纶复合空变纱为对象，研究短纤化效应对成纱表面性能的影响。认为：二醋酯长丝在空气变形加工中，部分单丝发生断裂而在空变纱表面形成自由毛羽端头的现象，主要由常规速度下的拉伸作用造成，所以二醋酯纤维的低强度是其空变短纤化效应产生的主要因素；二醋酯长丝的空变短纤化程度增加时，成纱摩擦系数、质量不匀、压缩回复能力呈下降趋势，外观不匀程度趋于增大，芯吸高度的变化则没有明显规律。更多还原

【Abstract】 As one of the most important cellulosic fiber, diacetate filament has been available commercially in 1920’s. During a quite long period, diacetate filament has been mostly used to produce linings for top grade garments. By the end of 20 century, its application scope changed markedly and began to involve three sections including fabrics, linings and adornments. However, its manufacturing technology is still monopolized by a few multinational companies currently. In our country, there is little literature pertaining to original studies such as spinning and product development for diacetate filament.In light of developing diacetate filament targeted to produce textiles, samples of diacetate filament were made under different spinning conditions by the laboratory spinning machine for diacetate tow used in tobacco, and effect of spinning parameters on mechanical properties was discussed in this paper. When other parameters are kept constant, higher concentration of spinning dope results in higher fiber tenacity; under same dope concentration, fiber tenacity tends to increase with increase in residual solvent content; when hot air temperature is increased, the mass specific resistance is reduced; when dope concentration is decreased, the mass specific resistance is increased. Such structure properties as thermal property, crystallinity, orientation and morphology of diacetate fiber were tested by various methods including TG, DSC, X-ray diffraction and SEM. It was found that diacetate fiber would decompose in temperature of 220～260°C, and there are two characteristic melt peaks on DSC spectrum; its degree of crystallization and orientation are relatively low, as a result, diacetate fiber is poor in tenacity and wear resistance; fiber’s cross section presents a shape of irregular tooth-like square and there are grooves on the longitudinal surface. Aiming at the disadvantage of its low tenacity, diacetate filament was heat treated under dry or wet heat environment respectively. Effects of temperature, time and tension on tensile property of diacetate fiber were discussed. The results show that the tensile property of diacetate fiber changes little after dry heat treatments without tension, but changes significantly after dry heat treatments with tension, and in the case of being treated by both dry heat treatment with tension and wet heat treatment without tension, diacetate fiber exhibits greater modification on tensile property.Secondly, air texturing was applied to process diacetate filament, and propertiesof yarn and fabric were examined in this paper. It was observed that higher airpressure is not practical during the air texturing of diacetate filament, or else, thetexturing process can not be carried out smoothly. The tenacity and breakingelongation of air textured diacetate yarns are quite lower. Diacetate fabric is poor intensile strength, tear strength and wear resistance, but good in anti-pilling tendency,subdued in luster and soft in handle. Herein, according to the design concept oflearning from others’ strong points to offset one’s weakness, synthetic filamentsincluding polyester and polyamide were chosen to blend with diacetate filament toproduce core-and-effect air textured yarns. Effects of core yarn on properties ofblended yarns and morphological structure of air textured diacetate/polyester yarnwere mainly analyzed. The results show that the introducing of synthetic filamentsmakes it possible to apply higher air pressure during the air texturing of diacetatefilament, which leads to a better texturing effect, and the process is very stable. It wasbelieved that the tensile property and shrinkage in boiling water of core-and-effectblended yarns are mostly depended on core yams. The three-dimensional videomicrographs revealed that there are some free diacetate fiber ends on surface ofblended air textured yarns by diacetate and synthetic filaments, which indicates that aspun-like effect of diacetate filament occurred when loops and arcs are formed onyarn surface. At lower overfeeds of effect yarn, loop/hair number is reduced withincrease in loop/hair height, the distribution of loop/hair number along height almostfollows an exponential curve, and loops or hairs are mostly located in height of0.5mm. With increase in overfeed of effect yarn, the distribution of loop/hair numberalong height gradually exhibits a quadratic curve, and loops or hairs shift to positionwith height of 0.5～1.5mm.Concerning the study on spun-like processing by air texturing for diacetate filament, influences of processing parameters and Texspun device on spun-like extent were discussed, the spun-like effects of different effect yarns during air texturing were also compared, and then an orthogonal experiment was used to optimize spun-like effect as well as yarn property. The influence of overfeed of effect yarn on hair number shows no obvious trend. With increase in overfeed of core yarn, hair number is slightly reduced. With increase in air pressure, hair number is increased in a way. At higher texturing speed, hair number tends to decrease. When winding underfeed is increased, hair number changes little, and the wetting of effect yarn results in a highest value of hair number. As a whole, the spun-like effect of diacetate filament during air texturing is insufficient under the single air texturing process, that is, the increase in number of free diacetate fiber ends on blended yarn surface is less. After treatment of Texspun, both hair number and loop number are increased, and the increase in hair number is higher than that in loop number, while yarn tenacity and stability are not affected. For different effect yarns, the increase in hair number or loop number differs from each other. When polyester or polyamide filaments are used as effect yarn, the increase in hair number or loop number is less. When effect yarn is diacetate filament, the increase in hair number or loop number is much larger, and its normal or Texspun yarn possesses the highest value of hair number. Orthogonal experiment shows that the first factor affecting hair number is texturing speed and the second one is air pressure, the overfeed of core yarn is the leading factor affecting yarn tenacity and instability, and the overfeed of effect yarn is the dominating factor for yarn core bulkiness.The spun-like shape of diacetate filament formed during air texturing was compared with rupture features of diacetate fiber reported in previous literatures as well as its tensile breaks under various extension rates, and then, the mechanism of air texturing spun-like effect of diacetate filament was briefly described, finally, influence of spun-like effect of diacetate filament on yarn surface property was investigated. It was believed that the fact that part of diacetate filaments break and form free fiber ends on yarn surface during air texturing is mainly caused by tensile action under normal extension rate, and therefore the low tenacity of diacetate fiber contributes most to its air texturing spun-like effect. With enhancing of spun-like effect, yarn frictional coefficient, mass non-uniformity, and compressional resilience tend to reduce, while appearance unevenness is increased and the wicking behavior does not show clear trend.更多还原