纱线的定义与性能特征

In traditional textile production，it has been common to make yarn from fibers（staple fiber or continuous filaments）first，and then produce a fabric from the yarn，so yarn is the basic material of knitted fabric and woven fabric.Yarn may be composed of one or more continuous filaments or of many noncontinuous staple fibers.The selection of fibers and the structure of the yarn will directly affect the properties of fabric made from them to a large extent.

在传统的纺织生产中，首先将纤维（短纤维或长丝）纺成纱，再由纱织成布，因此纱是构成针织物和机织物的基本材料。纱线可由一根或多根连续长丝或许多不连续的短纤维组成，纤维的选择以及纱的结构在很大程度上会直接影响其织物的性质。

Definition of yarn　纱线的定义

Yarn is an assembly of fibers and/or filaments，and can be used for weaving，knitting，rope-making，thread-making，embroidery，etc.In the book of Textile Terms and Definitions，yarn is defined as a product of substantial length and relatively small cross-section consisting of fibers and/or filaments with or without twist.Yarns can be broadly divided into three types：spun-staple yarn，continuous filament yarn and composite yarn，which can be subdivided further.Staple fiber yarns can be subdivided in a number of ways：by fibre length（short staple being less than 60 mm，long staple greater than 60 mm），by yarn construction（single，piled，cabled，multiple，fancy），and by spinning method（ring spun，rotor spun，twistless，fascinated，core spun，self-twist，friction spun yarns，etc.）.

纱是纤维/长丝的组合物，可用于机织、针织、制绳、制线和刺绣等。在《纺织术语及其定义》一书中，纱被定义为：长度大，横截面小，由加捻或不加捻的纤维/长丝所组成的产品。纱主要分为三类：纺织短纤纱、连续长丝纱和复合纱，还可进一步细分。短纤纱可按多种方式加以细分：按纤维长度（纤维长度小于60mm、纤维长度大于60mm），按纱的结构（单纱、绒毛纱、多股纱、复合纱和花式纱），按纺纱方法（环锭纺、气流纺、无捻、包缠、包芯纺、自捻和摩擦纺的纱等）。

Properties of yarn　纱线的性能

Fundamental knowledge of yarn properties provides a basic for understanding yarn selection and manufacturing.Here，we will learn basic properties of yarn through the basic terminology of yarns presented.

纱线性能的基础知识是纱线选择和生产的基础。在此，我们通过纱线的基本术语介绍来了解纱线的基本性能。

1.Yarn twist　纱线捻度

Yarn must be twisted in order to have certain strength，elasticity，elongation，gloss，hand and other physical and mechanical properties.Twist is inserted by rotating fiber strands in either a clockwise or counterclockwise direction.Or simply，twist can be inserted in either of two directions，clockwise or anticlockwise.The twist direction is represented by the letters S or Z.Most yarns spun on cotton systems have a Z twist.The amount of twist in a yarn is expressed as turns per inch（tpi）of yarn length.Usually，the twist is not distributed evenly throughout the yarn.Yarns that have low levels of twist are soft.While twist in a yarn increases，strength increases and pilling decreases.

为使纱线具有一定的强度、弹性、伸长、光泽、手感等物理机械性能，纱线必须加捻。加捻是将纤维束沿顺时针或逆时针方向旋转。或简单地说，加捻可以按两个方向施加：顺时针和反时针。捻度方向用字母S、Z表示。在棉纺系统中大部分纱线的捻度为Z捻。纱线捻度的大小用每英寸长度纱线上的捻回数（tpi）来表示。捻度通常不是均匀分配在整根纱上。纱线捻度低，纱就较松软，当捻度增加时，纱线强力增加而起球现象减少。(www.xing528.com)

2.Yarn size/Yarn number　纱线粗细/纱线细度

Yarn size or number is a measure of liner density.Yarn size or number can be expressed in various ways，such as number，metric count，number English（abbreviated as Ne），denier，etc.It is difficult to measure the diameter of a yarn because not all yarns have a circular cross-section，and some are easily deformed.The accepted way to indicate the fineness of a yarn is to give the count or linear density.The count is expressed as the length per unit mass.The linear density is expressed as mass per unit length.The International Standards Organization（ISO）has recommended the Tex system as the standard yarn numbering system.A major reason for its adoption is the ease with which yarn numbers can be calculated by simple measuring a length of yarn and then carefully weighing it.The higher the count in cotton yarns is，the finer the yarns are.The fabric made of high count yarn is thin and compact and of better quality.

纱线的细度是纱线线密度的一种度量方法。纱线的细度有多种表示方法，例如号数、公制支数、英制支数（缩写为Ne）、旦尼尔等。由于不是所有纱的截面都是圆形，有的纱是异形，因此测定纱的直径很困难。普遍使用的表示纱的细度的方法有：给出它们的支数或线密度。支数表示单位质量的长度。线密度表示单位长度的质量。国际标准组织（ISO）推荐特克斯（特）制为标准的纱线粗细测定体系，主要原因是通过简单地测量纱线长度并仔细称重便可方便地算出纱线的粗细。棉纱支数越高，表示纱越细，支数高的纱织成的织物既薄也紧密，质量更好。

3.Yarn strength　纱线强度

Yarn strength is an index of yarn tensile strength，which has absolute strength and relative strength.Yarn strength depends somewhat on fiber cohesion.If long fibers are made parallel to provide maximum contact between fibers，it is possible to produce a cohesive yarn stronger than the yarn produced by spinning the same fibers without aligning them.Twist also affects both strength and abrasion resistance.Low twist produces a yarn that pulls apart more easily.Yarn strength is also affected by fiber properties，yarn structure，blend ratio，atmospheric temperature，humidity，etc.For example，the higher the strength in fiber is，the higher the strength in yarn will be.

纱线强度是纱线承受拉力的指标，有绝对强度与相对强度。纱线强度跟纤维的抱合力有关。如果纤维长度长，且互相平行，纤维之间的接触长度最大，此时，纤维间产生的抱合力大于同样长度不规则排列的成纱。捻度还影响纱的强度和耐磨性，低捻度纱很容易拉断。纱线强度还受纤维性能、纱线结构、混纺比、大气温湿度等因素的影响。例如，纤维强度越高，则纱线强度越高。

4.Yarn evenness　纱线均匀度

Yarn evenness is one of the important indexes to measure yarn quality.During spinning，the yarn evenness is affected by various factors，such as spinning raw materials，internal quality of half-finished products，spinning drawing process，defects of drawing elements，temperature，humidity，etc.So，few yarns exhibit perfect evenness.Most have an occasional thick or thin place in the strand，and in yarns there may be neps or knots.Such yarns may produce fabric defects that affect appearance and performance.Control of evenness is an important component of yarn quality control.Uster equipment is commonly used to test the yarn evenness.

纱线的均匀度是衡量纱线品质的重要指标之一。在纺纱过程中，纱线的均匀度会受到各种因素的影响，如纺纱原料、半制品内在质量、纺纱牵伸工艺、牵伸元件缺陷、温湿度等。因此纱线都存在不匀，大多数纱都有偶发性的粗节和细节或少数纤维形成的棉结，这会产生织疵并影响织物的外观和性能。均匀度控制是纱线质量控制的重要内容。均匀度检测常用乌斯特仪。