what is Textile technology knowledge

1.Textile fiber: the fiber used to make textiles

Basic performance requirements of textile fibers
(1) The fiber length and fineness shall meet the requirements of textile processing technology and products stationed in Taiwan. Generally, the fiber ratio is 25-35mm and the fineness is 5000-6000.
(2) The fiber shall have certain softness and elasticity. That is, it is easy to deform under stress and has good deformation recovery ability.
(3) Fiber has a certain strength and can bear certain external forces. And it has fatigue resistance and wears resistance.
(4) In the same batch of fibers, the difference in thickness, length, and color shall not be too large.
(5) The fiber itself should have a certain stability and not be easy to produce a chemical reaction.

2. Natural fiber

Fiber originally in nature or obtained by artificial planting and feeding

(1) Cotton: fluff on plant seeds. Such as cotton and kapok.

(2) Hair is the hair of an animal. Such as wool, goat hair, rabbit hair, camel hair, etc. Wool has good elasticity, and the fiber is curly. It is suitable for textile wool and industrial felt.

(3) Silk: it’s animal secretion. Such as silk, pressed silk, Muru silk, etc. Among natural fibers, silk is particularly fine and tough.

(4) Hemp: fiber on the stems and leaves of plants. Ramie, flax, hemp and jute are all fibers on the stem. Sisal and banana are leaf fibers.

There are also natural fibers and mineral fibers, and asbestos is one of the main mineral fibers.

3.1 Chemical fiber

The textile fibers made of substances without textile properties through chemical manufacturing process and spinning are collectively referred to as chemical fibers, which can be divided into man-made fibers and synthetic fibers.
(1) Man made fiber: it is made of natural polymer materials, mainly cellulose, through chemical processing. Viscose fiber is the most widely used man-made fiber. The properties of viscose fiber are similar to those of cotton. Its wear resistance and strength are slightly lower than that of cotton. Its moisture absorption performance is particularly good. The fabric feels cool when wearing and is easy to dye. The biggest disadvantage is the large difference in dry and wet strength, which is 40 ~ 50% of the wet strength. At the same time, it also has the disadvantages of large shrinkage. Man made fibers also include copper ammonia fiber and acetate fiber.
(2) Synthetic fiber: it is developed on the basis of man-made fiber. It is made from simple low molecular substances (such as benzene, acetylene, ethylene, coal tar, etc.) by organic synthesis and then spun.
A. Nylon (polyamide fiber) is a kind of synthetic fiber with excellent performance and wide application. It is characterized by strong wear resistance and ten times higher than cotton. It is twenty times higher than wool, fifty times higher than viscose, and two to three times higher than cotton. It has good elasticity, light weight, good impact resistance, alkali resistance, acid resistance, moth resistance and mildew resistance. The disadvantage is poor light resistance. Under long-term illumination, the color turns yellow, the strength decreases, the heat resistance is poor, the shape retention is poor, the fabric is not neat, easy to wrinkle, the surface is smooth, and has a waxy feel.
B. Polyester (polyester fiber) is its fabric, which has excellent wrinkle resistance and shape retention. It is easy to dry after washing. It is iron free and does not wrinkle. It has high heat resistance and is better than nylon; Good wear resistance, second only to nylon, so it is an ideal textile material with good electrical insulation. The disadvantages are poor dyeing, easy pilling of the fabric, low water absorption and airtight feeling when wearing. Contact with Mars will melt into holes.
C. Acrylic fiber (polyacrylonitrile fiber) is very similar to wool in appearance and hand feeling, so it is called “synthetic wool”. It is widely used to replace wool or blend with wool to make fabrics. It has good warmth retention, elasticity and type retention, and the proportion is 11% smaller than wool. The fabric is easy to wash and dry, light resistance is better than natural fiber and other chemical fibers, and dyeing is bright. The disadvantage is that the wear resistance is not as good as other synthetic fibers, the alkali resistance is also poor, and the tensile elasticity is worse than wool. The elasticity of the fabric will gradually disappear after wearing for a long time.
D. Vinylon – (polyvinyl alcohol fiber) is characterized by good moisture absorption, up to 5% close to cotton. It can be used to replace cotton in civil clothing. Therefore, it is known as “synthetic cotton”. Vinylon has 1.5 ~ 2 times higher strength than cotton, good wear resistance, chemical corrosion resistance, no moth and mildew, and good sun resistance. The disadvantages are poor elasticity, easy wrinkling in weaving, reduced dyeing performance, not bright color, poor heat resistance, unable to cook and wash in boiling water for a long time, and the shrinkage of vinylon fabric is larger than that of pure cotton fabric.
E. Polypropylene fiber (polypropylene fiber) has the lightest proportion among all synthetic fibers at present, only 60% of cotton. It has high strength, good resilience and wear resistance, second only to nylon. It also has high bulkiness and thermal insulation. Polypropylene fiber can be blended with cotton wool, viscose and other fibers. The disadvantages are poor light resistance and dyeing, poor heat resistance, moisture absorption and hand feel.
F. Polyvinyl chloride (PVC) fiber has good chemical corrosion resistance, heat preservation, flame resistance and sun resistance; Wear resistance and elasticity are better than cotton; Its hygroscopicity is very small, its insulation is strong, and it is easy to generate and maintain static electricity. The knitted underwear made of chlorine fiber has a certain curative effect on rheumatoid arthritis. The disadvantage is poor heat resistance. It starts to shrink at about 70 ℃. After washing with boiling water, the shrinkage rate reaches 50%. Therefore, the nylon fabric should be strictly prevented from hot water washing or approaching high heat objects.
Filament – the continuous filament of chemical fiber is wound into a silk roll, which is called filament. Because the filament has bright luster, uniform surface luster and is not easy to adhere to dust, it can be processed into silk like fabrics.
Short filament – the continuous filament of chemical fiber is mechanically crimped and then cut short (generally between 30 ~ 150 mm). For example, polyester raw materials for polyester cotton blending and viscose for cotton viscose blending belong to staple silk. Medium and long fiber is also a kind of staple fiber products.

3.2 Raw cotton

Morphology and structure of cotton fiber
(1) The shape of cotton fiber is mature, the cross section of normal cotton fiber is waist shape, the cross section of immature fiber is flat belt shape, and the middle cavity is large; The shape of over mature cotton fiber is circular and the middle cavity is very small.
(2) The structure of cotton fiber is normal. The structure of mature cotton fiber can be divided into five levels: cotton wax, epidermis, primary layer, secondary layer and middle cavity.

3.3 Relationship between properties of cotton fiber and spinning

(1) Length: the normal range of cotton fiber length is 23 ~ 33mm. Long length, good uniformity, high yarn strength, less hairiness and smooth yarn. Cotton fibers with a length less than 16mm are called short fibers.
(2) Uniformity: the degree of difference in fiber length is called uniformity. The neat fiber length is conducive to the uniform thickness and strength of spinning.
(3) Strength: refers to the strength of a single fiber, with a normal range of 3.5 ~ 4.5g/fiber. Single strength is high, because the fiber is not easy to break, so the yarn strength is high. The number of fibers in the roving cross section is reduced, although the single strength is high, the yarn strength will not increase much.
(4) Fineness: refers to the thickness of a single fiber. The normal range of fineness is 5000 ~ 6500 (Metric).
(5) Maturity: refers to the degree of growth and maturity of raw cotton, that is, the ratio of fiber cavity width to wall thickness, expressed by maturity coefficient.
(6) Moisture content: refers to the moisture content of raw cotton.
(7) Impurity content: refers to the impurities contained in raw cotton, that is, the percentage between the weight of impurities and the weight of the original principle of the test. It is expressed by impurity content. Generally, the normal range is 1.5 ~ 3%.

4 Yarn

Yarn is a continuum of fibers arranged in parallel and orderly, which is spun by twisting and embracing each other, which is called yarn; Two or more strands of yarn twisted together is called thread.
(1) Yarn types: generally, there are the following types of yarns:
(1) Pure cotton yarn: yarn made of cotton fiber. It is divided into combed cotton yarn and combed cotton yarn.
(2) Chemical fiber yarn: yarn made of chemical fiber, including polyester fiber yarn, viscose, Fuqiang staple fiber yarn and vinylon yarn.
(3) Blended yarn: yarn made by blending two or more fibers. There are polyester and cotton, cotton and vinylon, cotton and acrylic, cotton and polypropylene, cotton and viscose, polyester and cotton and nylon blended yarn. It is divided into cotton type and medium length type.
(4) Strand: it is formed by combining and twisting two or more single yarns. It is called double strand, which is the most widely used.

5 Expression of fiber and yarn thickness

Fixed length system: in the specified length, the weight of the article is used as a sign to measure the thickness of the article, which is called fixed length system.
(1) Tex System: when the public moisture regain (8.5%), it is expressed in grams of the weight of articles with a length of 1000m (m), which is called tex (number), and expressed in NT:

(2) Number of strands: it is expressed by multiplying the total yarn number of strands by the number of strands. For example: 18 × 2、21 × 2. When the number of ply yarns is different, it is expressed by adding the number of single yarns (21 + 10).
Denter system: (generally refers to filament) when the moisture regain is determined, the denier is expressed in grams of weight with a length of 9000m, which is expressed by Nd:

6 Fixed weight system

A mark indicating the degree of thickness by the length of the article within the specified weight.
(1) English count: when the specified moisture regain is 9.89%, the yarn thickness is expressed by the length of 840 yards in 1 pound of weight: (when the specified moisture regain is 9.89%, the multiple of 840 yards in the length of 1 pound of sample yarn)

For example, 60 yarns means that there are 60 840 yards of yarn in a pound of yarn.
The greater the number of British yarn, the finer the yarn; The smaller the British count, the thicker the yarn;
Metric count: when the moisture regain is determined, it is expressed as the length of 1000m in 1kg weight. In NM

The larger the metric count, the finer the yarn.
Conversion between special number and metric number:
Nt × Nm=1000 Nt=1000/Nm Nm=1000/Nt
Conversion between number and English branch: NT × Ne =583.1
Cotton: number × English number = 583
For example, 60 British count yarn is converted into number: NT × 60 = 583 NT = 9.72 t
(1) Twist: the number of turns per unit length of yarn
Tex twist is expressed in 10cm turns
The twist of the imperial count is expressed as the number of turns of 1 inch
The twist of metric branch is expressed as the number of turns of 1 meter
(2) Twist direction of yarn: the twist direction is divided into Z twist (backhand) and S twist (smooth hand).
S twist: the twist direction of the fiber in the single yarn or the single yarn in the strand is S twist from bottom to top from right to left after twisting.
Z-twist from left to right, Z-twist for single yarn and S-twist for strand

7 Fabric original weave

It includes plain weave, twill weave and satin weave
Warp and weft yarn density of fabric: the number of warp and weft yarns arranged in the unit length of fabric.
A. Metric representation: it refers to the number of warp and weft yarns arranged within 10cm.
B. Imperial representation: refers to the number of warp and weft yarns arranged within 1 inch.
(1) Plain weave: in a weave cycle, there are two warp yarns and two weft yarns, four weave points, two warp weave points and two weft weave points.
(2) Twill weave: a weave cycle must have at least three warp yarns and three weft yarns, and there are oblique lines composed of warp weave points or weft weave points on the weave chart. The surface of twill weave fabric is composed of warp (weft) floating lines

8 Representation of fabric products

Metric: T / R 21 × 2\21 × 2 216.5\188.5 160
Polyester viscose blended product material: warp, 21 special ply, weft 21 special ply, warp density 216.5 \ 10cm, weft density 188.5 \ 10cm, width 160cm.
Imperial: T / R 28 × 2\28 × 2 55\48 63
Polyester viscose blended fabric: the warp and weft yarn is 28 British strands, with warp density of 55 \ inches, weft density of 48 \ inches and width of 63 inches.
Cotton yarn quality evaluation
It is assessed from two aspects according to the international standards: 1. It is assessed as “etc.” according to the physical indexes of cotton yarn stipulated by the state;

  1. “Grade” shall be evaluated according to the appearance defects of cotton yarn;
    The physical indexes of “rating” include: quality index and weight unevenness.
    (1) Quality index: it indicates the strength of cotton yarn.
    (2) Weight unevenness: the difference rate of cotton yarn weight per unit length. The smaller the weight unevenness, the more uniform the yarn and the better the quality.
    (3) Weight deviation: refers to the deviation percentage between the actual drying weight and the design drying weight of the yarn. The smaller the deviation, the better.
    The evaluation of “grade” cotton yarn refers to the number of appearance defects of cotton yarn, including the number of NEP impurities and evenness of sliver.
    (1) Number of NEP impurities: it indicates the impurity content of cotton yarn, the smaller the better.
    (2) Evenness of sliver: it indicates the unevenness in short segments of cotton yarn.
    Regulations on wool separation of natural color cotton cloth
    1、 Wool separation regulations: the unit of natural color cotton cloth is piece. It is determined by the combination of physical indexes, NEP impurities and cloth appearance defects.
  2. Physical indexes, evaluation of NEP impurities, and those whose physical indexes fall behind the following allowable tolerances are second-class products.
    (1) 10cm longitude and latitude density;
    Warp density: 1.5% or more smaller than the standard; Weft density: 1.0% or more smaller than the standard.
    (2) The warp and weft fracture strength is 8.0% lower than the standard.
    The defect rate of NEP impurities exceeds the specification.
  3. Evaluation of cloth defects: the evaluation of cloth defects shall be subject to the front.

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