Gray fabric
Gray fabric is a semi-finished product that has not been dyed and finished after the fibres have been spun into fabric. Dyeing and finishing companies often refer to uncooked and desized grey fabric as raw grey fabric. After cooking and desizing, the cloth is called cooked cloth.
The main factors affecting the quality of dyeing and finishing products are raw materials, technology, equipment, operation and environment, among which the quality of grey fabric has a great impact on the quality of dyeing and finishing products.
Dyed and finished Grey Classification
1 The fabric organization classification
Blank fabric according to the different forms of warp and weft yarn interweaving, constitute different organizations, so that the fabric has a different appearance and physical and mechanical properties. Commonly used fabric organization can be divided into five categories.
a ) Plain
Plain tissue has a tight structure and a flat surface, the coverage of warp and weft yarns is basically the same, and the tightness is not very different. The yarn in the blank fabric dry bamboo knot, cotton knot impurities, coarse diameter, wrong weft on the dyeing and finishing products are very obvious reflection. As the general spinning department a tube yarn will be concentrated in a section of the door width, very sensitive to the quality of the blank, the weft yarn requirements should be more important. High quality requirements of the dyeing and finishing products, warp and weft yarn should be separate with cotton, in raw materials, technology to give sub-care, especially for the warp density of high, low weft density of poplin fabrics.
b ) Twill
The surface of the twill tissue has a diagonal pattern made by the continuous articulation of long warp or long weft floating points. The intersection of warp and weft is less than in plain fabrics, so the weave density is generally higher than in plain fabrics, the fabric tightness is greater than in plain fabrics, and the warp density is generally higher than the weft density.
The fabric is two-up, two-down and three-up.
Two on two under the fabric front and back symmetrical, warp and weft yarn reveal basic consistent.
Three on the next fabric front warp yarn reveals more, warp yarn appearance defects easily exposed in the fabric surface. The weft yarn can be covered up because it is less exposed.
For this reason, it is important to focus on the quality of the warp yarn from the dyeing and finishing products. Hundred foot faults are formed in twill fabrics due to the lack of weft yarn roots and fabric organisation errors (equivalent to the thin weft of plain fabrics). Tweed fabrics have khaki, waffle, wow ki three categories. The tightness of the fabric is greater in khaki than in waffle, and is greatest in clacker. Generally the greater the tightness the greater the weaving difficulty, more likely to produce weaving defects.
c ) Satin
It is characterised by a satin pattern, with longer interweaving intervals and fewer interweaving points, so that the weave density can be higher. Fabric. The surface is flat and lustrous, soft to the touch and rich in eye-catching brilliance after dyeing and finishing with resin and electro-glazing. Satin fabrics are divided into horizontal and straight tributes. The front side of the horizontal fabric is mainly formed by the weft yarn, while the straight fabric is mainly formed by the warp yarn, with the weft yarn showing less than the warp yarn. In general, tribute satin is a medium to high grade product with high requirements for yarn defects.
2 The fabric fiber classification
Generally can be divided into pure natural fiber fabrics, pure chemical fiber fabrics and blended fabrics three categories.
Mixed textile is two kinds or… More than two kinds of fiber blended or interwoven fabrics, which have chemical fibers and natural fibers, different natural fibers, different chemical fibers between the blended and interwoven.
Blended textile must master the combination of fiber ratio in line with the provisions or standard requirements; blended fibers mixed and uniform, otherwise it will form a colour flower or strip shadow or even colour difference.
The spinning department of different mixing methods such as cotton packet mixing, multi-bin mixing, cotton strip mixing, its achieved mixing effect is different, can be based on the final finished effect of dyeing and finishing, the best requirements. Single dyed blended or interwoven products should be strictly controlled by the dyeing and dyeing process to achieve the same colour and shade of the two fibres.
Synthetic fibres such as polyester, polypropylene, vinylon and other spinning, due to the influence of static electricity, often produce winding leather rollers, winding roller, winding leather ring “three around” phenomenon, resulting in drafting device pressure failure and broken head, resulting in bamboo knots and thick weft and other yarn defects. This should be the focus of attention when accepting blank fabrics.
Polyester and cotton blends such as the use of several boiling water shrinkage rate differences in polyester blends, will produce “skirt crepe” defects after dyeing and finishing. Due to the electrostatic adhesion of polyester-cotton blends, white polyester-cotton yarns tend to form “sooty yarns”.
3 The fabric yarn classification
According to the fabric used yarn count (special number) different, generally divided into low (coarse special) fabric, in the (special) fabric, fine (fine special) fabric, high (special fine special) fabric four categories.
The general division is as follows:
Low count (coarse special) fabric: warp and weft count 32tex and above (18 and below) ;
Medium count (medium special) fabric: warp and weft count 20~30tex (19~29);
Fine count (fine special) fabric: warp and weft count 9~19tex (30~60);
High count (special fine special) fabric: warp and weft count 9tex below (60 above).
Low count fabrics are often used as coarse cloth, velvet, interlining, etc. with lower requirements. Medium and fine count fabrics are the most widely used varieties in daily use. High count fabrics are often processed into high-grade fine cloth, poplin, khaki, bari yarn, feather cloth. High-count fabrics are generally made of combed yarn with spinning combing process, and more thread fabrics, more than 60 counts need to use long-staple cotton or fine denier, ultra-fine denier chemical fiber spinning system. The higher the count, the higher the quality requirements.
High count yarns are spun with long intervals between yarn dropping and falling, easily producing soot yarns; high count yarns with high twist are easy to wrinkle, weft yarns generally need to be twisted, otherwise weft shrinkage and pigtail yarn defects will be formed; high count poplin and down fabric with high weft density are easy to produce yellow and white yarns; dense “bari yarns” are particularly demanding; dyeing and finishing blank inspection Special attention is needed.
4 The fabric warp and weft yarn density or tightness classification
General sparse fabric, its warp and weft yarn density is low, tightness is small, such as maier yarn, bari yarn, gauze, mosquito net cloth, mesh fabric and other light fabrics. Medium-dense fabrics refer to the general common use of fabrics. Tight fabrics refer to fabrics with higher density and tightness, such as corduroy, plain wool, rainproof fabrics, down fabrics, high-count poplin, etc. The classification is not yet quantitatively defined.
General sparse fabric warp and weft yarn coverage is smaller, revealing more, to the strip dry uneven, coarse knots, details, all kinds of defects at a glance, so the requirements are higher. Tight fabric tightness high (generally in about 90%), weaving difficulty, most likely to produce three jump (jump flower, jump yarn, star jump) and other defects; cloth surface requirements flat, smooth, dry, knotted also have high requirements. Tight fabric because of the contrast of the weft yarn colour contrast enhancement, to the yellow and white yarn also correspondingly increase the chances.
5 Degree of fabric elasticity classification
Stretch fabric is a very popular product in the current market. Because of its comfortable wearing, can fully reflect the beauty of the human body, get men and women old and young favor. Stretch fabrics have warp stretch, weft stretch, warp and weft two-way stretch three kinds, with weft stretch for more. Stretch fabrics obtain elasticity through stretch yarns. Stretch fabric appearance defects are broken silk, silk and lack of silk, it will cause after dyeing fabric local uneven elasticity, wrinkling, blistering and colour flowers and other defects, should pay special attention.
6 Fabric pile products
Blank fabrics are mainly used for pile dyeing and finishing products, such as velvet, corduroy and flat pile.
General pile fabric has bleached pile, printed double-sided pile, beige pile, etc., are woven by low and medium count yarn, most by weft pulling pile, so weft yarn twist should be low. After the weft is stretched, the strength of the fabric is reduced by almost half, so the weft yarn should have a higher strength. In terms of spinning faults, tightly twisted yarns should be avoided, with particular attention being paid to the instantaneous twisting caused by the jointing of fine yarns. The weft shrinkage of pile blanks is large, generally between 11% and 16%, which means that the width of the blank should be enlarged compared to normal fabrics. For the pile effect, coarser raw materials such as batting are generally used.
The fabric organisation of corduroy consists of two parts: the pile and the ground; the pile can have a pile weft or a pile warp. Generally, pile weft is the most common. The pile warp or weft is processed by a pile cutting machine to form the corduroy strip.
Corduroy is characterised by a high degree of tightness, generally with a small warp density and a large weft density, about 1:2.5~3 in this case. Due to the high tightness, it is necessary to strengthen the management of cotton blends to prevent yellow and white yarns.
The surface of flat pile fabric is covered with even, flat pile, with a soft lustre, soft texture and elasticity.
Flat pile is divided into two categories: cut weft or cut warp. The weft and warp densities are relatively high, with the weft density of cut weft plain pile being 3-5 times higher than the warp density to ensure fabric fastness and to prevent delinting. The tightness of the fabric is 55% to 60% in the warp direction and 160% to 220% in the weft direction, which makes it difficult to weave and creates a high chance of defects. Flat pile is a high-grade product, warp and weft yarns are often used with high strength combed strands such as J14x2, J10x2.
The requirements of different dyeing and finishing processes for Grey
Different dyeing and finishing processes have different requirements for blanks, and for different objects, different treatments can obtain more, faster, better and more economical results.
1 Bleached blank fabric
Blank cloth by boiling bleaching, cloth surface clear and white, and the residual coloured blemish on the blank cloth will be exposed, so the oil blemish, colour blemish on the blank cloth, such as oil warp, oil weft, colour warp, colour weft, coal ash yarn, hemp silk, hair silk, grass silk (together called three silk) and other blemishes should be given special attention. Chemical fibre blends and pure spinning products have higher requirements for these defects due to their higher whiteness. Compared to dyed blanks, bleached blanks are slightly less demanding in terms of dryness, knotted impurities and small yarn faults.
2 Dyed blanks
Dyed blanks are divided into two categories: miscellaneous blanks and dark blanks. Processing similar to 190 shilling blue cloth and the colour of the lighter colour cloth for the miscellaneous blanks, deeper than 190 shilling blue cloth colour for the darker blanks.
Dark coloured blanks: due to the darker dyeing, there is a strong contrast with the original colour of the cloth. In order to prevent colour differences caused by uneven dyeing, there are high requirements for defects such as cotton knots, tight warp, loose warp, tight twist yarn, loose twist yarn, wrong weft, thin weft, hundred feet, bamboo knots and other textile defects.
The problem of white stars in dark coloured blanks is a particularly prominent quality key, mainly formed by low maturity fibres such as border flaps, soft seed surfaces and dead fibres in the original cotton, resulting in the failure of dyestuffs to take on colour, and must be noted.
Miscellaneous coloured blanks or light coloured blanks are similar to bleached blanks, with higher requirements for oil and colour defects, and slightly higher requirements for general yarn faults such as dryness, cross-density and cross blocking than dark coloured blanks. The visual impact of different colours on the cloth can be different. In my experience, the colours of schmaltz, snow blue and beige are very sensitive to the appearance of streaks on the cloth.
3 Printed blanks
Printed blanks because the visual impact of the pattern is the first, so relatively dry, cotton knot impurities and spinning, weaving the impact of defects is less, but the prominence of some defects on the surface of the cloth, such as horizontal block, bamboo knot, thin weft, 100 feet, wrong weft, weft shrinkage, jumping flowers also need to pay attention to.
It must be pointed out that dyeing and printing of blanks must not be mixed with the wrong fibres (different fibres), which will cause very obvious defects. Recently, polypropylene packaging cloth often in the spinning department to open the cotton process mixed in, resulting in adverse effects. The effect is even greater when mixed with foreign fibres in the warp. In order to prevent the mixing of different fibres, dyeing and finishing blanks can be used before the use of ultraviolet light (commonly known as black light) test, to identify natural fibres and chemical fibres confusion has considerable effect.
4 Resin finishing cloth
Resin finishing can improve the fabric wrinkle resistance, crease recovery, to achieve non-iron, shrinkage, improve the feel and drapability of the effect. But the resin finishing will make the fabric strength significantly reduced, so the resin finishing of the blank, requiring high strength, especially such as high fabric, Barry yarn fabric, itself because of the high count strength low, must focus on the resin finishing strength changes, to ensure that the taking requirements.
Strengthen the management of grey fabric
Dyeing and finishing enterprises must designate departments responsible for the management of blank cloth, maintain contact with cloth supply units, communicate information in a timely manner, and advocate the development of spinning, weaving and dyeing as a whole collaboration and research activities.
The focus should be on the following points.
1 into the factory cloth must be accepted, according to the special blank dedicated, the principle of first in the first use, according to the supply factory blank, batch number, package number are stacked for use. The raw material and process of the supplying factory should be changed if there is a big change.
2 To carry out random inspection on the quality of blank fabric, the general sampling rate should reach 3%. To test the width, warp density, weft density; according to the key requirements of the blank fabric to test the appearance of defects; to test the fabric strength index for the high requirements of the blank fabric strength.
3 found that the quality of the blank fabric problems, to supply fabric enterprises to send people to verify and correct in a timely manner. Sudden and large quality problems must stop production to investigate the cause and trace the responsibility.
4 the blank fabric sewing head to do a good job to identify the logo, sewing head should make the edge of the cloth aligned, evenly pulled flat, straight, not to have creases, sparse type of fabric requirements of the joint both sides of the additional sewing measures to prevent the edge of the roll open off.
5 It is recommended to implement the system of “instruction manual” for blank fabrics for the reference of dyeing and finishing enterprises.
