Elastic fiber has entered all aspects of people's daily life, is an indispensable raw material for textile and clothing in life, but all the clothing we wear has elasticity because of the role of spandex components.
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Main Characteristics of Spandex Fabric
1. & nbsp; & nbsp; spandex has very high elasticity. Generally, the products do not use 100% polyurethane, and most of them mix 5-30% in the fabric. All kinds of spandex fabrics have 15-45% comfortable elasticity.
2. & nbsp; & nbsp; spandex is usually not used alone. Spandex fabrics are usually made of composite yarns, such as spandex as the core, and other fibers (such as nylon, polyester, etc.) as the skin to make core-spun yarn elastic fabrics. It has good adaptability to the body, and is very suitable for tights, without feeling of compression.
3. & nbsp; & nbsp; spandex elastic fabrics are similar in appearance style and service performance to those of the same kind of coated outer fiber fabrics.
In the dyeing and finishing process of spandex, if the process is not proper, it will cause problems such as elasticity and wrinkle. Therefore, the dyeing and finishing of spandex must focus on these two major issues, and adjust the process appropriately to meet customer requirements.
In order to improve the spinning performance of spandex, silicone oil lubricants and other additives are used in weaving process. These additives will degrade naturally over time, resulting in yellowing of the fibers and a decrease in the elasticity of the fabric. At the same time, spandex-containing fabrics will form & ldquo; cold setting & rdquo; in the long-term storage, which will cause permanent wrinkles that can not be eliminated in the post-processing of fabrics. Therefore, apart from reducing the storage time, the more important thing is to open the knitted fabric immediately after weaving and roll it in flat, so as to avoid the chance of indentation.
When the knitted fabric containing spandex fibers is off the machine, the spandex fibers in the knitted fabric have certain internal stress formed during weaving. Therefore, the purpose of preheating and setting is to eliminate the stress through a relaxation process of the fabric, to make the size of the fabric fully stable, and to eliminate the permanent creases in the post-processing of the fabric. If the second coil is on the left side of the first coil, the feed direction should be 7%-10%(relative width) in front of the left side of the first coil in the predefined shape, so as to keep the twist of the finished product in line.
Predetermined type
Therefore, the best predefined scheme is:
Relaxation & rarr; Steaming (80 C rolling hot water without steaming conditions) & rarr; Overfeeding & rarr; (Into fabric pretreatment & rarr; Shaping & rarr; Printing).
Most dyeing factories roll water directly into the setting because they do not have steam equipment. When the temperature is below 10 degrees (winter), the fabric is prone to creases. The fabrics are loosened through the steam box before setting, and satisfactory results will be achieved. The heat setting temperature is between L85 and 190 C, and the setting time is between 45 and 60 S. If the setting temperature is too high, the fabric will yellowish.
At the same time, if the impurities and additives on the fabric are partially degraded due to the influence of baking, and once the degradable substances migrate to the fiber, they will be difficult to remove in the later processing. Oil spots in the fiber will first absorb dyes during dyeing, but can not run out in time during the heat preservation and dyeing process. In order to form deep stains, even after stripping and re-dyeing, it will remain on the fabric. Therefore, we must avoid the high temperature predefinition above 195 C (note: the softening temperature of spandex is about 200-deg; above), and it will also affect the fastness of spandex. When setting, the width is 1 0%-1 5% wider than that of the gray cloth, so that it has a full recovery during the pretreatment in the dyeing vat, so that the internal stress of the fabric can be completely eliminated.
Pre-processing
The knitted fabrics that need printing also need to be pretreated to remove cotton stain impurities and grease wax, increase the whiteness of the fabrics and improve the wettability and water absorption of the fabrics, so as to achieve good printing effect. Pretreatment process can be divided into two categories: traditional alkali treatment and modern enzymatic treatment. Bioenzymatic treatment meets the requirements of environmental protection processing, but it is difficult to meet the requirements of fabric with high bleaching or bleaching requirements at present. Therefore, conventional alkali treatment process is still widely used. Washing of spandex fabric after pretreatment is carried out one by one. Stepwise cooling is necessary to prevent fibers from shrinking and creasing due to sudden cooling.
Shaping requirements for semi-finished products
Shaping of semi-finished products must be carried out according to the original design process. Generally speaking, the width of shaping is about 3%-5% wider than the width of finished products. The meridional shrinkage rate is controlled within the required shrinkage rate of finished products. The extension of the sticker is equal to the proportion enlarged when drawing. If it is one-sided knitted fabric, then it also needs the control of blade trimming and optimum twist to reduce the printing weft skew caused by twist. The width of the pulp edge is about 1 cm, and the pulp breaks point. Should not be too thin or too thick, too thin to play its due role, too thick will affect the printing effect near the edge. Paint printing can be lighter in terms of width and shrinkage due to the fact that the paste retained on the fabric surface will relatively increase the square metre quality of the fabric.
