Dyeing and finishing process of modal printed home textile fabrics

Abstract: The factors affecting fabric shrinkage, active printing enhancement, anti-pilling, seam slippage and hand feel during the dyeing and finishing process of modal printed home textile fabrics were analyzed, and the optimized process conditions were obtained as follows: the mass concentration of alkali oxygen cold-batch caustic soda in the pretreatment is 6-8g/L; P-type and K-type reactive dyes are used for printing, the dosage of urea, alkali agent and anti-dyeing salt S is increased, and the steaming time is extended; amino silicon softener and polyurethane finishing agent are combined for post-finishing, the stretching temperature is 1605-170℃, and the speed is 35-45m/min.

Keywords: woven fabrics, dyeing and finishing, shrinkage, seam slippage, furniture fabrics, modal fiber

Introduction

Modal fiber has the advantages of softness and fluffiness. The fabrics made of it are soft and crisp, and the cloth surface is bright and shiny. It is widely used in knitted underwear, clothing fabrics, etc. Home textile fabrics made of modal fiber are moisture-absorbent, breathable and comfortable.

Modal home textile fabrics have a bright luster, and mercerization is not necessary for printing and dyeing. However, in the actual printing, dyeing and finishing process, there are problems such as difficult to control the weft shrinkage rate, pilling indexes that do not meet the requirements, poor anti-seam slippage performance of the fabric, and light color of deep and thick colors. To this end, the production process is optimized to solve the above problems and make the processed products meet market requirements.

1 Dyeing and finishing process

1.1 Fabric

Use 100% Modal fiber, five-piece three-fly satin fabric, 14.62tex×14.62tex, 523 strands/10cm×315 strands/10cm, width 268cm

1.2 Process flow

Turn the cloth seam head → singeing and rolling amylase extinguishing → stacking → washing → alkaline oxygen cold stacking → washing → adding whitening agent to stretch → rotary screen printing → steaming → washing → adding soft stretching → calendering → pre-shrinking → finished product inspection and packaging.

1.3 Pretreatment

1.3.1 Singeing, padding, amylase quenching and cold stacking

Modal has poor anti-pilling performance, so the singeing strength should be appropriately increased. However, too heavy singeing is not conducive to the desizing in the later process, so a two-positive and one-reverse medium-sintering process is adopted, and the speed is controlled at 100-110m/min.

In the weaving process of Modal, most of the starch slurry and chemical slurry are mixed for sizing, and the proportion of starch slurry accounts for more than 70%, so the use of amylase desizing is very effective, which can remove most of the starch slurry and is conducive to the removal of residual chemical slurry in the later washing process.

Add 5-8g/L amylase to the fire extinguishing tank, directly pad the amylase working solution after singeing, wrap the cloth with plastic film in the cloth car after dropping to prevent air drying, and stack it for 4-6h; then wash it thoroughly in a continuous washing machine.

After amylase desizing and washing, most of the impurities on the cloth surface are removed, but a small amount of slurry and impurities still remain, affecting the whiteness of the cloth surface. In order to improve the quality of semi-finished products, alkali oxygen cold stacking treatment is required.

1.3.2 Alkali oxygen cold stacking

(1) Process prescription/(g.L-1)    Caustic soda        6～8

100% hydrogen peroxide      13～15

Hydrogen peroxide stabilizer    10

Refining penetrant         5

(2) Process conditions

Two dips and two rolls, roll residue rate 90%, roll cloth on A bracket, stack at room temperature for 24h, and wash and dry on a continuous washing machine.

(3) Process analysis The purpose of alkali oxygen cold stacking is to remove residual slurry and impurities (such as sulfides, wax, oils, etc. on viscose fibers), improve the whiteness of semi-finished products, the depth of printed color and the brightness of some bright colors. The role of hydrogen peroxide, in addition to decomposing residual slurry and improving whiteness, is more importantly to further remove reducing substances such as sulfur or sulfide remaining in the production process of modal fiber, reduce the damage to dyes during printing drying and steaming, and improve the utilization rate of dyes.

In actual production, it is found that the amount of caustic soda has a great influence on the color of printing and the performance of the final product. If the amount of caustic soda is large, the shrinkage rate of the finished product cannot meet the requirements, the anti-pilling performance deteriorates, and the feel is also affected; if the amount of caustic soda is too small, the color of printing is low, so the amount of caustic soda should be optimized.

Under the condition that other process conditions remain unchanged, 4 different amounts of caustic soda are used to cold-pile modal fabrics, and then washed and dried.

Test method: Wash and dry the semi-finished product samples according to the SA procedure in GB/T 8629-2001 "Household Washing and Drying Procedures for Textile Testing", and measure the width of the semi-finished product before and after shrinkage. The width of the fabric after shrinkage is the stable width. The Martindale method was used to determine the anti-pilling performance of semi-finished products, the fixed load slip test method was used to determine the seam slip, and the blind touch method was used to evaluate the feel of four fabric samples.

With the increase in the amount of caustic soda, the width of the semi-finished products gradually decreased, the anti-pilling performance also decreased, the feel became worse, and the fixed load seam slip decreased, whether before or after shrinkage.

The four pre-treated semi-finished products were sewn together for printing, and the color yield after printing was compared. With the increase in the amount of alkali oxygen cold stack caustic soda, the color yield of the light color part was not much different, and the color yield of the dark color part gradually increased. Process D was obviously lighter, but the difference between processes A, B, and C was not obvious. Caustic soda and scouring agent produce a synergistic effect, and saponify the oil agent remaining on the cloth surface, which is beneficial to remove impurities and improve water absorption. Caustic soda can destroy the dense cortical structure of modal, which is beneficial to dye adsorption and penetration during printing and improves dye utilization.

Increasing the amount of caustic soda will cause serious fiber swelling, increase the diameter, and increase the fabric buckling wave height, which will have an adverse effect on the shrinkage rate of the finished product.

(4) The natural width of the semi-finished product will gradually decrease with the increase of the amount of caustic soda.

According to the SA shrinkage test method, the sample is the stable width of the fabric after washing. When the width requirement of the final finished product remains unchanged, the closer the width after shrinkage is to the finished product width, the better the weft dimensional stability; the warp shrinkage can be controlled by pre-shrinkage in the finishing process. When the width requirement of the finished product is certain, increasing the stable width of the semi-finished product plays a key role in controlling the weft shrinkage.

During the long-term stacking process, caustic soda will inevitably cause modal fiber to fibrillate, reducing the anti-pilling performance of the fabric. With the increase of caustic soda, the smooth surface of the modal fiber is destroyed, and the feel gradually becomes rough due to the removal of oil and wax substances on the fabric. However, the friction between the yarns increases, and the seam slip performance of the semi-finished product is slightly improved.

Considering the comprehensive indicators such as shrinkage rate, anti-pilling, printing color, feel and seam slippage, the caustic soda concentration should be 6-8g/L.