The nylon thick elastic mesh fabric refers to a warp-knit elastic mesh fabric with a basis weight of 170-200 g/m2, which is mainly used for the production of underwear. The texture of the underwear made of nylon is compact, stiff and elastic.
Due to the high content of spandex (usually 15% to 30%) and large denier (140 to 420 dtex) in such nylon warp-knit thick-elastic mesh fabrics, dyeing and shaping are more difficult. According to the conventional process of chemical fiber-type elastic knitted fabrics , the finished products can easily produce obvious straight lines and curling . To this end, the product's pre-treatment and shaping process flow and process conditions were optimized and screened, achieving good results.
Process test
1.1 Materials and Equipment
Nylon warp knitted thick elastic mesh fabric for fabric processing (main specifications 70 D nylon × 210 D spandex, 70 D nylon × 140 D spandex, 40 D nylon × 280 D spandex, 70 D nylon × 420 D spandex, etc.)
Reagents: Degreasing agent 8099, soda ash, chelating agent , glacial acetic acid, ammonium sulfate, softener 440 in bath, acid levelling agent NEW (Deime Chemicals).
Dyes: Acid Red E-BNL, Acid Yellow E-2FL, Acid Blue E-BGL.
Equipment; six-slot continuous refining code degreasing washing machine, high temperature and high pressure overflow dyeing machine, resin stenter setting machine.
1.2 Process flow
Washing→ Staining →Dehydration→Medium Inspection→Shaping→Heat Shrinkage→Dehydration→Medium Inspection→Drying→Inspection→Packing
2. Determination of process flow
2.1 Pretreatment
2.1.1 process flow
The process of the conventional dyeing and finishing of chemical fiber-type elastic knitted fabrics (washing→pre-setting→staining→dehydration→middle inspection→determination→checking→packing) is adopted to process the nylon elastic thick mesh fabric, and the fabric cloth will produce obvious straight lines. phenomenon. This may be due to the influence of residual oil stain on the spandex spandex. The oil used for spandex warping is mainly oil or white oil, and other lubricants and macromolecular structure pastes are also added.
The spandex used for nylon elastic mesh fabrics has a large denier and a high content. If the grey fabric is washed or dry-cleaned and then immediately enters the former shape, the residue that has not been completely removed from the fabric is free to the surface of the fiber under high temperature conditions to form a tar stain. In view of this, a new pre-treatment process was designed: washing → dyeing → dehydration → medium inspection → setting. That is, the grey cloth directly enters the dyeing after washing . After dehydration, mid-inspection and final product setting, the dyeing effect of the cloth surface was significantly improved, the color uniformity was good, and no straight or yellow dots were visible to the naked eye.
2.1.2 Washing and Degreasing
At present, there are mainly two ways to remove oil from the chemical fiber-type elastic warp knit fabrics : one is to wash the oil in the dyeing tank, and the other is to clean the oil in the flat washing machine. Dyeing tank washing and degreasing process is simple, with few processes and low cost. However, because the elastic warp knit fabric contains spandex, it is required to loose the cloth before washing in the cylinder, and the gray cloth is easily stacked in the cloth to form an extrusion crease. In addition, the high-spandex spandex knitted elastic fabrics need to be stitched after being loosely stretched, so as to prevent curling of the fabric and formation of creases. The use of a flat washer washing and degreasing method, due to the mesh belt steamer to make the fabric in a tension-free state of relaxation, the fabric before and after the mesh wheel is equipped with a spread roller, can be fully free to shrink; distributed above the drum 6 high pressure The water spray pipe can carry out large-flow spray, plus an external water pump circulation system, which can make the washing liquid in the tank evenly stirred up and down, and has better washing effect. Therefore, in the actual production, the flat washer washing machine is used to remove oil.
2.1.3 Washing machine oil removal process conditions
(1) Equipment
Six-slot continuous refining code degreasing washing machine, cloth speed 30m/min.
(2) Water washing and degreasing process
Loose cloth → Dipping scouring solution (55°C) → Scouring (80°C) → Scouring (95°C) → Vacuum water absorption → Hot wash (85°C) → Vacuum water absorption → Hot wash (75°C) → Vacuum water absorption → Neutralization (60°C) → Vacuum Water Absorption → Cold Wash (Normal Temperature) → Vacuum Water Absorption
(3) Washing and degreasing process recipe
2.2 Staining
High-temperature and high-pressure overflow dyeing machine is used for dyeing. During the operation of the model, the impact of nozzle flow on the nylon warp-knitted thick-elastic mesh fabric is less, which can reduce the water impact on the fabric, reduce the pilling phenomenon, improve the fabric feel and improve the cleanliness of the fabric.
2.2.1 dyeing process curve
Process Description:
After the grey cloth is put into the cylinder, it is run in the machine for 5 minutes, and the auxiliary agent is slowly added according to the prescribed amount.
After 4 additives are added, the cylinder will continue to run for 5 minutes. After the dye is dissolved and filtered, it will be injected into the sub-cylinder, diluted with 1:100 warm water, and then injected into the master cylinder.
After leveling at room temperature 5min, ammonium sulfate was added buffer, adjusted to pH 5 to 6, the control color uniformity.
Dye according to the prescribed procedure.
2.2.2 Dyeing prescription
Nylon thick elastic mesh fabric (light brown)
Acid Red E-BNL/% (owf) 0.0265
Acid Yellow E-2FL/% (owf) 0.025
Acid Blue E-BGL/%(owf)0.0093
Acid levelling agent NEW/(g/L)1
Ammonium sulfate/(g/L)1.5
Acetic acid / (g/L) 0.1
Bath softener 440/(g/L)2
2.3 Finishing
2.3.1 Process Flow
The nylon elastic mesh fabric was dyed directly after washing, and then pre-shaped after dyeing. If the grey fabric is not shaped, the stability of the finished product width is poor, and the curl of the two fabric edges is severe. After being cut, the large pieces of material are curled up on both sides, and the small pieces of material are rolled into strips, which makes it difficult to process the garments. With the final two-finishing process, there is no obvious improvement in the curling phenomenon and the hand feel is affected. To this end, the following finished shaping process was developed: set shape, high temperature shrinkage, dehydration, middle inspection, drying, inspection and packaging.
After the finished product is set, a high temperature shrinkage and drying process of the incoming cylinder is added. The grey fabric is washed in the dyeing tank for a certain period of time, so that the tension received in the process is recovered, and the finishing and softening agent are dried at a low temperature. The dimensional stability of the finished product, and get a good flexibility and feel.
2.3.2 shaping process conditions
(1) Equipment
Resin stenter.
(2) Process conditions
Set the temperature of Section 1 to 2 oven 200 °C, Section 3 ~ 8 oven 195 °C, Section 9 oven 190 °C.
Speed ​​30 r/min.
Thermal circulation fan speed 3 500r/min.
Transfection was dyed in a wet state into the oven, so that the first two oven temperature was decreased due to evaporation of water, the heating temperature is lower than the actual fabric sections after the oven, thus setting the first two high set temperature to 5 ℃, To improve the shape effect. The oven temperature setting in the last section is 5°C lower than in the previous sections because it is the last time to enter the cold air zone, which is conducive to stable web width and improved hand feel.
2.3.3 High Temperature Shrinkage Process Conditions
(1) Equipment
High temperature and high pressure overflow dyeing machine.
(2) Process conditions
Temperature 80°C
Holding time 20 min
Bath ratio 1:12
Select 80°C thermal shrinking water in the process to avoid water washout due to excessive temperature. Adding 0.1%~0.3% glacial acetic acid in dark colors will help reduce the phenomenon of residual dye re-coloring after washing and increase the color depth and washing fastness accordingly.
2.3.4 Drying process conditions
(1) Equipment
Resin stenter.
(2) Process conditions
Drying temperature Section 1-2 oven 155 °C, Section 3 ~ 8 oven 150 °C, Section 9 oven 140 °C.
Speed ​​50 r/min.
Thermal circulation fan speed 3 500r/min.
Since the final setting has already stabilized the fabric width and fabric weight within the process setting range, the drying only needs to be restored to the set requirement. Requires the rear vehicle operator to keep track of the humidity, fabric width, weight, feel, and curling of the cloth at any time, and to meet customer orders by controlling the speed of the vehicle.
3. Conclusion
By optimizing the pre-treatment, dyeing and shaping process of the nylon thick-net mesh fabric, the straight-line phenomenon of the fabric after dyeing is solved. The process adopts the previous treatment and then goes directly into the cylinder for dyeing; the final setting of the product is controlled to control the setting temperature and the speed of the vehicle, and the width and weight of the fixed fabric are stabilized within the requirements set by the process, and the high temperature shrinks the tension caused by the fabric during processing. It can be restored to efficiently solve the phenomenon of fabric straightness and fabric curling due to large denier and high content of spandex in the warp-knit thick-elastic mesh fabric of nylon warp, so that the product quality can meet the customer's final requirements.
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