Technical class
Introduced the production process of Tencel LF/cotton blended fabrics, including low-alkali cold pad batch, short steaming, cold pad batch dyeing and finishing. The pretreatment adopts enzymatic desizing and then singeing, low-alkali cold pad batch and short steaming processes. The dosage of caustic soda in the cold pad batch is 10~12g/L, the short steaming temperature is 100~102℃, and the steaming time is 2 minutes; cold pad batch dyeing is used. The fabric is rich in color and has excellent color fastness to multiple washes: hydrophilic softeners and polyurethane finishing agents are used for post-finishing, which not only gives the fabric a good hand feel but also improves the fabric’s resistance to pilling.
Tencel LF is a new regenerated cellulose fiber developed by Lenzing. Tencel LF has the excellent properties of Tencel fiber such as soft hand, beautiful luster, good drape, high strength, and dimensional stability after washing. Tencel LF fiber adds a cross-linking agent during the fiber production process. Compared with ordinary Tencel fiber, Tencel LF fiber has a lower degree of fibrillation. Tencel LF fiber does not require prior fibrillation and enzyme treatment and can be processed on traditional dyeing and finishing equipment like other cellulose fibers.
Tencel LF has a strong affinity with dyes and good same-color properties with cotton fibers. After dyeing, the fabric has bright color and excellent color fastness. The cold pad-batch dyeing method is used during dyeing, which not only saves energy, but also makes the fabric dyed more evenly. Tencel LF/cotton blended fabrics can improve the wash color fastness of the fabric through cold pad batch dyeing, which can solve the problem of cotton fabrics after multiple washings
Fading problem.
1 Test equipment
1. Materials and equipment Fabric:
Tencel LF55/cotton 45, 160cm, 11.7tex/11.7 tex, 693/10cm×338/10cm, 3/1 twill; pure cotton, 11.7tex/1 1.7tex, 693/l0cm×338/10cm, 3/1 twill.
Reagents: reactive blue RGB, reactive red RGB, reactive yellow RGB, NaCl, Na2C03/fixing base. Equipment: Rapid prototype machine, Rapid sample steaming machine, induction cooker, SDL/ALATS washable color fastness tester.
2. Test
Breaking strength: According to ASTMD 5034 “Fabric Breaking Strength and Elongation Test Method (Grab Sample Method) “test.
Color fastness to washing: tested according to AATCC61-2A “Color Fastness to Home and Commercial Washing of Textiles: Rapid Method”.
Color fastness to rubbing: tested according to AATCC8 “Color Fastness to Rubbing of Textiles”.
Washing dimensional changes: tested according to AATCC135 “Dimensional Changes in Fabrics at Home Washing”.
Anti-pilling performance: Tested according to ASTM D3512 “Textiles’ Pilling Resistance and Surface Change Test”.
Gross effect: Take a 15cmX2cm sample and put it vertically into the water for 0.5cm, and measure the height of the water rising in 1 minute.
Whiteness: Use Data CoiorSF600 computer colorimeter to measure 4 times at different positions on the fabric and take the average.
2 Test sample
1. Dyeing process
Tencel LF/cotton blended fabric and pure The semi-finished products of cotton fabrics are dyed separately. The dyeing formula is:
Reactive blue RGB20.0g/L, orange RGB0.7g/L, and red RGB0.4g/L. Process flow: pad dyeing solution → drying → pad steaming solution (NaCl/Na2C03) → steaming (time 60s) → cold water → soaping → drying.
Tencel LF55/cotton 45 dyeing formula:
Reactive blue RGB 20.Og/L, orange RGB 0.7g/L, red RGB 0.4g/ L. Pad dyeing process: pad dyeing solution → drying → pad steaming solution (NaCl/Na2C03) → steaming (time 60s) → cold water washing → soaping → drying. Cold pad batch process: Preparation of dye and alkali agent (fixing alkali 60g/L) → mixing of dye fixing alkali (volume ratio of dye solution and fixing alkali 4:1) → rolling → rolling → stacking (stacking temperature 25～35℃, time 10h)→wash→soap→wash→dry.
2. Color fastness
Compare Tencel LF/cotton blended fabric with The semi-finished cotton fabric was dyed and washed with water, and the color fastness was measured. The results are shown in the table. It can be seen from Table 1 that the original discoloration fastness of Tencel LF/cotton blended fabric and pure cotton fabric is 4.0. As the number of fabric washing times increases, the original discoloration fastness of Tencel LF/cotton blended fabric is better than that of pure cotton. Fabric.
Table 1 Color fastness to washing of Tencel LF/cotton blended fabrics and pure cotton fabrics
Tencel LF55/cotton After 45 was dyed with different methods, the color fastness to washing was tested. The results are shown in Table 2. As can be seen from Table 2, the color fastness to washing of the cold pad batch dyeing process is higher than that of the pad dyeing process. When dyeing using the cold pad batch dyeing process, after the fabric is padded into the dyeing solution, the Tencel LF and cotton fibers will intensify their puffing under the action of the alkali agent in the dyeing solution, which is beneficial to the adsorption and diffusion of dye molecules, and at the same time prolongs the dyeing time, and the dye is fully Top dyed, full color. The cold pad-batch dyed fabric is more uniform and transparent when pad-dyed with a long lathe, and at the same time, it can avoid the white core problem that is easy to occur with long lathe pad-dying. Therefore, cold pad batch dyeing has better color fastness to washing.
Table 2 Effect of dyeing methods of Tencel LF/cotton fabric on color fastness to washing
3 Cart Production
1. Production Equipment
Singeing machine, desizing machine, cold pad batch dyeing machine, washing machine, tenter machine, pre-shrinking machine (Montfuji ).
2. Fabric specifications
Tencel LF55/cotton 45.
Production process
Seam turning → enzyme desizing → singeing → cold pad batch pre-treatment → short steam washing →Mercerization→Cold pad-batch dyeing→Washing→Tentering→�shrink.
3.1 Enzyme desizing
During the weaving process of Tencel LF/cotton blended fabrics, most of them use starch slurry and chemical After mixing and sizing, enzyme desizing can remove most of the starch sizing, and the residual chemical sizing can be removed in the water washing process. After enzymatic desizing and washing, the slurry on the cloth surface is removed, and the hairiness floats on the surface of the fabric, which is beneficial to the removal of hairiness and improves the singeing quality.
The desizing process is as follows: desizing enzyme 2000L 6g/L, penetrant 2g/L, temperature 80-85℃, time 30min; rolling residue rate 80-85℃, water washing 4 grids, 90~95℃. At the same time, the wrinkles during the packaging process are removed to make the cloth surface smoother.
3.2 Singeing process
The anti-pilling performance of Tencel LF fiber is poor, so the intensity of singeing should be increased appropriately. It can improve the anti-pilling properties of fabrics. Singeing after enzymatic desizing can not only improve the singeing effect, but also improve the feel of the fabric. After singeing, the singeing level needs to reach level 4. Singeing process: vehicle speed 120m/min, flame temperature 1000℃, burner ports: one positive and one negative.
3.3 Low-alkali cold rolling batch pre-treatment process
Tencel LF fiber is regenerated cellulose fiber and does not contain impurities. Cotton fiber contains natural impurities such as cotton seed hulls and pectin. After enzymatic desizing and water washing, most of the slurry is removed, but a small amount of slurry and impurities remain. In order to ensure the dyeing depth and good cloth surface quality and feel, the slurry and impurities must be further removed. The cold pad pre-treatment process uses the joint action of caustic soda and hydrogen peroxide during stacking to expand, swell and degrade the slurry and impurities on the fabric, which are then removed by short steaming water washing. The dosage of caustic soda in the cold pad batch is determined to be 10-12g/L, which can effectively reduce the fibrillation of Tencel LF fiber and improve the pilling performance of the fabric.
3.4 Short steaming and washing process
Short steaming and washing process:
100% NaOH 5～6g/L, 100% H202 2～2.5g/L, refining agent 88EC0 8g/L, steaming temperature 100～102℃, steaming time 2min.
Tencel LF fiber can obtain better whiteness and wool effect after alkali-oxygen cold stacking, but cotton fiber can only obtain ideal wool effect after steaming . Steaming and water washing after cold padding improves the wool effect and whiteness of the fabric, and the semi-finished product indicators meet the dyeing requirements. After short steaming treatment, the indicators of the semi-finished product are warp breaking strength 669N, weft breaking strength 428N, wool effect 4.3cm, and whiteness 74.
3.5 mercerized
Tencel LF has good alkali resistance and can be Mercerizing improves fabric gloss and dyeing properties. During mercerization, the fiber is significantly and fully swollen, the thickness of the fabric is increased, and the hand feel is fuller. At the same time, the stiffness of the fabric is reduced during subsequent wet processing, and the occurrence of scratches and creases is reduced. After the fiber is fully swollen, the dye molecules are more likely to enter the gaps of the fiber during dyeing and diffuse into the interior, and the dye uptake rate is significantly improved. The mercerizing machine must be washed thoroughly, and alkali on the cloth surface is strictly prohibited.
Mercerization process: NaOH 180～190g/L, time 40～50s, drop cloth pH=6～7.
3.6 dyeing
Process flow: Preparation of dyes and alkali agents→mixing of dye fixation alkali (volume ratio of dye solution and fixation alkali 4:1)→rolling→coiling→stacking (stacking temperature 25~35℃, time 10h)→ Wash → Soap → Wash → Dry.
3.7 Finishing
Hydrophilic softener is used in the finishing process to give the fabric excellent hand feel and drape. properties, so that the fabric’s good moisture absorption and breathability can be fully reflected. Polyurethane finishing agent PU is a self-crosslinking polyether polyurethane polymer that can form a thin film on the fiber surface and between fibers. It can not only improve the hand feel, but also give the fabric permanent hydrophilicity and improve the fabric’s durability. Anti-pilling and anti-wrinkle properties.
4. Finished product testing
The test results of finished fabric indexes are shown in Table 3.
Table 3 Fabric finished product indicators
4 Postscript
1 .The singeing of Tencel LF/cotton blended fabrics after enzymatic desizing is beneficial to improving the singeing effect, improving the anti-pilling performance of the fabric, and improving the feel of the fabric.
2. The use of low-alkali cold pad treatment can effectively reduce the fibrillation of Tencel LF fiber and improve the anti-pilling performance of the fabric.
3. The cold pad batch dyeing process is used when dyeing. The dyeing time is long, the dye is fully dyed, and the color is full. Cold pad-batch dyeing is more uniform and transparent with longer car pad dyeing, which avoids the white core problem that is easy to occur in long-car dyeing. Therefore, cold pad-batch dyeing has better color fastness to washing.
4. Use hydrophilic amino silicone oil softener and polyurethane finishing agent for post-finishing, which not only improves the fabric feel, improves fabric drape, moisture absorption and breathability, but also gives the fabric a lasting affinity Water-based, improves the anti-pilling and anti-wrinkle properties of fabrics. </p
