涤纶长丝仿棉假捻变形纱的结构和基本性能

就新型仿棉假捻变形纱的纱线结构、卷曲性能、强伸性能、条干均匀度、表面浸润等性能进行了全面研究,并与纯棉纱和常规假捻变形纱进行对比分析.结果表明:较常规假捻变形纱,新型仿棉假捻变形纱具有明显的粗细节结构,使其具有一定的短纤纱外观特性;其热收缩率和和卷曲收缩率较常规假捻变形纱大,这可能与其纱体中含有2种长丝组分有关;其断裂强度和断裂伸长率明显比常规涤纶假捻变形纱小.在棉纱断裂伸长率范围内,新型仿棉假捻变形纱的强伸曲线与棉纱强伸曲线基本吻合;而其与水滴的接触角比纯棉纱和常规假捻变形纱小,水滴在新型仿棉假捻变形纱表面快速铺展浸润,表明该纱具有优异的导湿性能.新型仿棉假捻纱总体外观形态具有一定的仿棉效果,而其强伸、弹性回复和导湿性能超越纯棉纱.     

变形纱成纱熵变和膨松性能的关系

纱线成形过程主要以纤维或丝束空间排列秩序性的变化为特征,因而存在着熵变现象,大多数变形加工过程具有熵增加的特点。熵是状态函数,因此变形纱熵变和其膨松性能关系密切,理论推导表明,成纱熵变和膨松指数的对数成正比,与膨松度呈正相关关系;变形纱紊乱度值与膨松指数在数值上相等,与膨松度呈正相关,实验结果与上述结论一致。由于变形纱紊乱度在数值上与纱线膨松指数值相等,因此可以通过测定纱线膨松指数的方法测量变形纱线的紊乱度值,进而量化研究成纱熵变的大小。     

利用光衍射测量长丝纱的变形结构

无变形的长丝纱倾向于以一种平行且均匀的方式排列在一起。相比于表面不太均匀且包含毛羽的短纤维纱线,无变形的长丝纱表面很光滑。在很多应用中,人们期望可在保留长丝纱连续性的同时获得短纤纱的某些特性。通过变形丝工艺,可以使长丝纱获得特定的性能,如高膨松性、高弹性和孔隙度。在实验室中,可以离线测量变形纱的性能,但还没有实现对运行过程中的纱线进行性能的实时在线光学检测。离线测量方法成本高,且只能获得随机纱线样本质量的统计信息。除介绍了最先进的变形纱参数的测量外,还提出了一种直接光学测量变形纱的潜在方法。     

变形纱成纱熵变和膨松性能的关系

纱线成形过程主要以纤维或丝束空间排列秩序性的变化为特征,因而存在着熵变现象,大多数变形加工过程具有熵增加的特点.熵是状态函数,因此变形纱熵变和其膨松性能关系密切,理论推导表明,成纱熵变和膨松指数的对数成正比,与膨松度呈正相关关系;变形纱紊乱度值与膨松指数在数值上相等,与膨松度呈正相关,实验结果与上述结论一致.由于变形纱紊乱度在数值上与纱线膨松指数值相等,因此可以通过测定纱线膨松指数的方法测量变形纱线的紊乱度值,进而量化研究成纱熵变的大小.     

Effect of nozzle size on texturing performance: comparison between air-jet and steam-jet texturing

The objectives of this research work were to investigate the use of steam in order to replace air in the production of spun-like textured yarn and to investigate the optimum nozzle size for steam-jet textured yarn for the application of sewing thread. An existing air-jet texturing machine was modified to supply either air or steam to the texturing nozzle. Using four texturing nozzles, both air-jet and steam-jet textured yarns were manufactured. The effect of nozzle size on process and yarn parameters has been studied and compared with air-jet textured yarns. The results show that spun-like textured yarn manufactured using steam has lower loop instability and higher tensile properties than air at comparable fluid pressures. SEM image analysis shows that the entangled structure of the steam-jet textured yarns is similar to air-jet textured yarns. Further, sewability results show that steam-jet textured yarns are suitable to manufacture sewing threads.     

Steam as an alternative fluid for air in spun-like texturing: effect of core-yarn draw and core-yarn heat setting on texturing performance

The objectives of this research work were to investigate the use of high-pressure steam in order to replace air in the production of spun-like textured yarns and to investigate the effect of core-yarn draw ratio and core-yarn heat setting on texturing performance. An existing air jet texturing machine was modified to supply either air or steam to the texturing nozzle. Using an identical nozzle, both air-jet and steam-jet textured yarns were manufactured. Results show that the core-yarn and textured yarn tension increase and the loop instability decreases when the core-yarn draw ratio is increased. Therefore, it can be predicted that the core-yarn draw ratio has influence on the performance of both air jet and steam jet texturing. Boiling water shrinkage of core-yarn as well as air-jet and steam-jet textured yarn increases when the core-yarn draw ratio was increased. However, steam-jet textured yarn has lower boiling water shrinkage than both core-yarn and air-jet textured yarn. Core-yarn heat setting does not have influence on core-yarn and textured yarn tension in the air jet texturing. In steam jet texturing, core-yarn heat setting reduces core-yarn and textured yarn tension. Therefore, it can be predicted that core-yarn heat setting is important for steam jet texturing.     

变形纱成纱熵变对条干均匀度的影响

长丝变形纱在变形加工过程中,其成纱熵变是增加的。成纱熵变是状态函数,其与变形纱紊乱度的对数成正比,因此成纱熵变对变形纱的表观条干均匀度有显著影响。随着成纱熵变和紊乱度不断增加,变形纱的外观和性能均发生明显改变,其表观CV值迅速增加,并接近短纤维纱条干CV值,仿短纤维纱化效果明显。这种状况可通过长丝变形纱表观直径变化总频数及频率分布加以表现。由膨松结构引起的空气变形纱表观条干均匀度值的异常改变使其与质量条干均匀度值不相关,这是变形纱区别于传统短纤维纱的主要特征之一。     

29—TWISTING-RATE VARIATIONS IN THE FALSE-TWIST THREADLINE. PART I: BACKGROUND AND THE EFFECT OF A STEP CHANGE IN THE TWISTING RATE

A previous publication has shown that changes in the twisting rate in false-twist texturing cause the generation of real twist in the final yarn. The equations developed in the earlier analysis assumed an even distribution of twist in the processing zone. New equations are presented that extend the original analysis and take account of the findings of recent investigations into processing-zone twist distribution.     

Investigation of the effect of core-yarn wetting on air-jet and steam-jet spun-like texturing performance

The objective of the research work was to investigate the use of steam as an alternative fluid for air in spun-like textured yarn manufacturing and to investigate the effect of wetting on texturing performance. An existing air-jet texturing machine was modified to supply either air or steam to the texturing nozzle. Both air-jet and steam-jet textured yarns were made using the same process parameters with and without core-yarn wetting. The effect of core-yarn wetting on the texturing performance has been studied. Results show that core-yarn wetting is critical for air-jet texturing but do not have considerable impact on steam-jet texturing. Therefore, core-yarn wetting could be eliminated in steam-jet texturing. Further, steam-jet texturing shows its capability in manufacturing spun-like textured yarns with better performance than the air-jet. Therefore, it can be concluded that steam can be used as an alternative fluid for air in making spun-like textured yarns without core-yarn wetting.     

变形纱条干均匀度与变形工艺参数的关系

由于条干均匀度是评价纱线外观特性的重要指标,与短纤维纱不同,变形纱线的表观条干均匀度和质量条干均匀度不相关。为最终达到空气变形纱线及其多重变形纱线结构和性能设计的目标,对长丝原料及几个关键变形工艺参数进行了初步的单因子试验。结果显示,异收缩空气变形纱的条干均匀度可以通过选择单、复丝线密度,空气变形加工和异收缩变形加工工艺参数的方法加以有效控制。空气变形加工工艺参数中的超喂率和喂入方式,异收缩变形加工工艺参数中的异收缩率、平均收缩率对成纱的条干CV值有显著影响。     

28—RATES OF SETTING IN FALSE-TWIST DRAW-TEXTURING PART I: THE EFFECTS OF HEATING TIME AND LENGTH IN THE PROCESSING OF POLYESTER-FIBRE YARNS

The increase in the crimp contraction of textured polyester-fibre yarn with increasing heating time is shown to follow an exponential relation similar to that for yarn temperature. Setting rates for fully drawn and partly oriented yarns can be evaluated by using such a relation. It is shown that processing speeds can be increased by a factor of about two for the simultaneous-draw-texturing process compared with the texturing of fully drawn yarn, but crimp stability is lower and has to be considered. Dyeing behaviour is also examined. Changes in the light reflectance of dyed fabric with varying heating time in texturing occur more slowly than do those in crimp contraction, but the amplitude of these changes is not large if dyeing is performed at 130°C.     

Threadline Instability in the False-twist Texturing Process Part II: The Influence of Process Parameters on Threadline Instability

An account is given of an experimental investigation into the effects of the major parameters involved in threadline instability in the false-twist draw-texturing process when disc-friction twisting units are used. The effects are interpreted in the light of the critical yarn speed, the critical draw ratio, and the wavelength and amplitude of the tension surging described in Part I of this series. Tension surging in the texturing of fully drawn yarns and in crossed-belt friction- twisting is also considered.     

Characterizing bulkiness and hairiness of air-jet textured yarn using imaging techniques

Abstract

Control of product characteristics during production is very important to achieve improvement in quality. This importance come into consideration in yarn texturing because of high demand for textured textiles. In this investigation, new methods are introduced for the determination of air-jet textured yarn's structure, applying computer vision and image analyzing techniques.

Since the size, density and distribution of loops are very important factors in air-jet textured yarns,they are determined measuring yarn diameter, hairiness and torque indexes and applying imaging techniques. The measured features are successfully utilized in the proposed method to quantify texturing characteristics.     

涤纶细旦变形丝工艺的探讨

对单丝纤度为1、2—1、67dtex的涤纶变形丝的加工技术进行了探讨,研究了喷丝板、纺丝能力、侧吹风、变形条件等对纤维质量的影响。结果表明,只要合理选择工艺参数,可以在现有的高速纺设备上生产出性能稳定的单丝纤度较细的涤纶变形丝。其织物手感丰满,悬垂性能好。     

变形纱线膨松性能的表征与EIB测试:2.工艺参数与膨松度的关系

 为最终达到空气变形纱线及其多重变形纱线结构和性能设计的目标,对长丝原料及几个关键变形工艺参数进行了初步的单因子实验。结果显示,异收缩空气变形纱的膨松度可以通过选择单、复丝的线密度、空气变形加工和异收缩变形加工工艺参数的方法加以有效控制。空气变形加工工艺参数中的超喂率和喂入方式,异收缩变形加工工艺参数中的异收缩率、平均收缩率对成纱的膨松性能有显著影响。     

长丝变形纱缠结结构研究

缠结结构是变形纱的基本结构特征之一,较好地解释了变形纱的诸多物理现象,如变形纱结构的稳定性,空气变形纱抗弯刚度过高等等.变形纱的缠结结构与紊乱结构同时产生于变形加工过程中纤维片段的转移,因而二者关系密切,互为依存条件,可以用缠结点密度和缠结度表征变形纱缠结结构的锁节程度.采用物理质点一轻质弹簧理论,分析系统中各结点的作用力学关系,可获得各结点运动的牛顿力学方程.变形纱缠结程度与其抗弯性能关系密切,可采用间接测试方法.     

用MPS变形机生产花式长丝

描述了德国巴马格公司的MPS变形机的特性和应用.MPS变形机的理念使长丝生产商对于市场的需求能作出迅速有效的响应.已生产的长丝大致可分为三类:与通常变形丝手感不同的长丝、与标准变形丝染色特性不同的长丝及在某种程度上同时显示以上两种特性的长丝.     

11—AN INVESTIGATION OF THE AIR-JET BULKING PROCESS

Experiments aimed at investigating the mechanism of the air-jet bulking or texturing process led to an interesting observation that the textured yarn emerging from the venturi was rotating in such a way as would temporarily untwist the yarn while it was in the jet. The indication is that false-twisting (or untwisting) occurs owing to the vorticity of the turbulent air in the wake of the yarn feed needle that bifurcates the air-stream. The various yarn-processing conditions separately affect the amount of false twist inserted. There is evidence to show that the direction of the vortex, and hence of the untwisting action, is dependent on whether the angular displacement of the feed needle from its central position is in a clockwise or anti-clockwise direction. A suggested mechanism of the process based on the untwisting and retwisting of the overfed filaments offers an explanation for the characteristic locked-in loop structure of air-bulked yarns.     

假捻集聚纺纱线的特征分析

探讨假捻集聚纺纱线的性能特点.测试了不同捻系数假捻集聚纱线的各项主要性能,并与同捻度的传统环锭纱线进行了对比试验分析.结果表明:捻系数为280的假捻集聚纱线.其条干CV值均比同捻系数的传统环锭纱差,而纱线的毛羽指数、断裂强度和断裂伸长率也只有在假捻器转速比适当的条伴下才好于传统环锭纱.而当捻系数为360时,假捻集聚纱线的条干CV值和断裂强度只有在假捻器转速比较低时才好于传统环锭纱,而毛羽指数和断裂伸长率则可在较大的假捻器转速比范围内优于环锭纱.     

聚酯细旦双捻向低弹网络丝生产工艺探讨

介绍采用ＰＯＹ—ＤＴＹ工艺路线生产单丝纤度０．８７ｄｔｅｘ细旦双捻向低弹网络丝的生产技术，讨论了切片干燥、熔融纺丝和牵伸假捻及异捻合股网络等条件的控制．