Polyester-spandex knitted fabrics have the advantages of good drape, comfortable covering, rich and soft feel, comfortable wearing, and breathability. Comparable taking performance, thus winning a broad market. As people have higher and higher requirements for the color fastness of clothing fabrics, they also have high requirements for the washing color fastness of printed and dyed polyester/spandex products. For example, six-fiber staining is level 4, and the color fastness to immersion is level 4 to 5.
Production process
Polyester-polyester knitted fabric → oil removal and washing (loose type pre-shrunk washing machine, 60~95℃, 7 tanks) → acid Washing (glacial acetic acid 0.5 g/L) → Preforming (195～205℃, 15 m/min) → Dyeing (130℃, 50 min) → Acid reduction cleaning (90°C, 15 min) → Alkaline reduction washing (90 ℃, 15 min) → acid neutralization (glacial acetic acid 0.5 g/L) → final product shaping (130～140℃, 15～30 m/min) → test.
Production process
1. Pre-treatment
1.1 Refining, oil removal and water washing
Principle: polyester ammonia Elastic fabrics contain a lot of spinning and weaving oils and spandex amino silicone oil, which must be completely removed before dyeing to prevent the oil substances from forming lakes with dyes, causing problems such as fabric color flowers and color stains. However, silicone oil agents are difficult to remove using ordinary scouring conditions and are the main cause of dyeing defects such as stains. Therefore, spandex-specific scouring agents must be used to fully perform the scouring process.
Refining equipment: Choose a continuous heated spray type pre-shrinking washing machine (more than six sections). The loose-type pre-shrinking washing machine can effectively remove oily substances while ensuring that the cloth surface does not produce any Wrinkles are beneficial to the smoothness of the cloth surface after dyeing.
Recipe for scouring: high-efficiency scouring emulsifier 20-30 g/L, soda ash 2g/L
Fabrication requirements: After degreasing and washing, the cloth needs to be determined in time; the pH of the cloth surface Value ≤7.5; the less high-efficiency scouring emulsifier residue on the cloth surface, the better, and it must be washed clean. In order to ensure that the cloth surface is clean, the pre-shrinking effect is optimal, and the grease on the cloth surface is cleanly removed, the vehicle speed should be set based on the weight of the fabric to 15-30 m/min.
1.2 Pre-shaping
Principle: During the weaving process of polyurethane elastic knitted fabrics, the presence of large residual stress inside the gray fabric will cause the fabric structure to deform. . If the residual stress in this area is not eliminated, problems such as creases and stripes may easily occur during the dyeing process of the fabric. At the same time, the width and weight of the fabric will be difficult to control, and shrinkage will be unstable. The purpose of pre-shaping is to eliminate the internal stress of spandex and stabilize the quality indicators such as fabric width, unit area quality and fabric elasticity, so as to prevent it from shrinking during the dyeing process and affecting the dyeing effect, and no error will occur in subsequent processes. Big changes. The quality of the pre-forming effect will directly affect the subsequent processes. If the pre-forming temperature is too low and the speed is too fast, the wrinkles on the cloth surface will not be easily removed, and it is easy to form broken marks, curling and unstable width during dyeing. ; If the pre-setting temperature is too high, the fabric will turn yellow and hard, and its strength and elasticity will decrease, and even the spandex will break. Therefore, it is necessary to strictly control the preforming process conditions, have a certain positive overfeed during preforming, and lower the rolling tension rod.
Shaping equipment: eight-section or ten-section open width shaping machine.
Pre-forming process: clean water in rolling car, rolling car pressure 5 N/cm2, setting machine temperature 195~205℃, vehicle speed 18~30 m/min, overfeeding 15%.
Fabrication requirements: The cloth surface should be flat; the cloth should be dropped on a breathable net bucket (to prevent hot press creases); when necessary, the air volume should be appropriately increased to achieve timely cooling of the cloth surface (cloth surface temperature requirements after placement) as normal temperature).
2. Dyeing
2.1 Dye Selection
Disperse dyes generally stain spandex seriously, so you must consider both when screening disperse dyes It has good coloring performance and good dyeing properties. At the same time, the staining on spandex can be easily removed. When dyeing with ordinary disperse dyes, the spandex fiber is stained seriously and is not easy to remove. In the end, the fastness indicators of polyester and spandex fabrics do not meet customer needs.
2.2 Dyeing equipment
High-temperature and high-pressure overflow jet dyeing machine: The use of overflow dyeing machine can reduce the tension and pulling force on polyester and polyurethane fabrics under high temperature conditions , will not cause damage to the elasticity of polyester-spandex fabrics, keep the fabrics in a relaxed state and avoid shrinkage.
2.3 Dyeing process
Disperse dye dyeing requires high temperature and high pressure. Polyester fiber has better coloring effect under high temperature conditions, but spandex is not resistant to high temperature. Under such conditions, spandex yarns are prone to brittleness, resulting in reduced strength, broken wires, defects and other problems. Therefore, in order to balance polyester and spandex fibers, after testing and production research, the dyeing temperature was selected to be 130°C, which can satisfy the polyester coloring situation and is better. to avoid damage to the spandex. Similarly, dyeing time, dyeing pH value, heating rate and cooling rate will all cause damage to spandex fibers. After experiments and mass production tests, in order to reduce damage to spandex, the dyeing time was selected to be 40 minutes, the dyeing pH value was 3.8 to 4.5, and the dyeing temperature rise was controlled within 1°/min. If the temperature rises too fast, it will cause color discoloration due to insufficient holding time. For flowers, the cooling should be controlled at 1-1.5 °C/min, because cooling too fast will cause chicken paw prints and even colored flowers.
2.4 Reduction cleaning
In the dyeing of polyester-spandex knitted fabrics, the staining of spandex by disperse dyes is inevitable. The purpose of reduction cleaning is to remove the fabric. The floating colors on the fabric and the disperse dyes adsorbed on the spandex surface improve the color fastness of the fabric to washing. Restorative cleaning must take into account the effective removal of floating colors on fabrics and staining on spandex.At the same time, we must also consider that the discoloration of the fabric is within a controllable range. After a period of on-site practice, we adopted the following restoration cleaning method, which achieved various fastness indicators to meet customer requirements. At the same time, the discoloration caused by restoration cleaning of the fabric was also eliminated. Within controllable range.
Generally, polyester fabrics dyed in dark colors only need alkaline reduction cleaning, but for polyester and spandex knitted fabrics. In order to completely remove the floating color on polyester and the staining on spandex, after continuous experiments in large-scale production, it was found that after dyeing polyester and spandex fabrics, adding an acidic reduction cleaning before the alkaline reduction cleaning can significantly improve the setting Color fastness of finished polyurethane knitted fabric. The reason may be: adding thiourea dioxide immediately after dyeing polyester and spandex for acid reduction cleaning, which not only eliminates the need for drainage and acid neutralization washing, shortens the process flow, but also effectively initially removes floating colors on polyester and spandex. The staining can ensure sufficient reaction in the next step of alkaline reduction cleaning, and further remove residual floating color and staining, thereby effectively improving the color fastness of polyester-spandex fabrics.
Reduction cleaning method: The dyed polyester and ammonia fabrics are reduced and washed using a two-bath and two-step combination process, with acidic reduction cleaning first and then alkaline reduction cleaning.
Acidic reduction cleaning process recipe: thiourea dioxide 3.0% Alkaline reduction cleaning process recipe: 36BeNaOH 3.0%, insurance powder 4.0%
2.5 before leaving the tank Fastness test
Water immersion fastness test: 5-6 g/L commercial Diao brand washing powder is soaked in heated water at 85°C for 3-4 minutes, and at the same time, put in the undyed polyester and polyurethane fabric lining cloth. Look at the color of your feet. After testing, the color faded slightly due to foot water, and the lining cloth containing spandex of the same fiber hardly stained.
Finished product shaping
Polyester and polyurethane fabrics need to be shaped as soon as possible after dyeing. It should not be stored for too long after dyeing. Leaving it for too long will easily produce creases and discoloration. migrate. Like pre-shaping, the whole process of setting the finished product is low tension. The fabric to be determined is evenly and loosely distributed in the cloth car. Under the condition of ensuring that the surface of the polyester-spandex fabric is smooth and wrinkle-free, the setting temperature should not be too high.
Shaping equipment: eight-section open width shaping machine.
Shaping process: the temperature is controlled at 110~130℃; the speed is 20~30 m/min; the addition of hand feeling additives can be done in the feeding tank, and the rolling pressure is 4 N/cm2. </p
