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Easy problems and solutions in polyester-cotton dyeing

Views: 4     Author: Site Editor     Publish Time: 2022-02-16      Origin: Site

Color difference in polyester-cotton dyeing

(1) Form

1) The fabric has different shades and shades; (between cylinders)

2) Including the depth of the side, the depth of the left and right, the depth of the front and back, the color of the front and back, and the color of the front and back parts;

(2) Causes

The dye is not evenly distributed on the fabric in the early stage. If the dye is not evenly distributed on the fabric before the fixation, it must be a color difference after the fixation; (the dye is unevenly colored on the cloth)

1) Fabric factor: the quality of semi-finished products is not good; (pretreatment is not in place)

2) Rolling factor: the over-rolling rate of each part is inconsistent; (the reason for the long car equipment,

Polyester-cotton dyeing shade changes

1) Factors before dyeing: the whiteness of the fabric and the pH value are quite different (the higher the pH value is 7-10 alkaline, it is easy to glow red)

2) Dyeing factors: overreaction of conditions, such as overreduction;

3) Post-dyeing factors: In the post-finishing process, such as resin finishing, high temperature tentering and different pH values on the fabric; (temperature related)

Forms, causes and overcoming methods of color difference in long-running dyeing of polyester-cotton blended fabrics

1. Color difference on both sides

1) Dyeing liquid padding: the amount of liquid on both sides is inconsistent;

2) Pre-baking and baking: the degree of drying is uneven or insufficient;

2. Side-center color difference and left-center-right color difference

1) The roll axis is deformed, resulting in inconsistent overroll ratio;

2) The temperature and air volume are inconsistent between the middle and both sides of the cloth during pre-baking or hot-melting;

a) In the case of general empty car, the middle temperature is higher than the temperature on both sides (baking oven) (hot melt);

b) When dissipating heat, both sides are easy to dry, while the middle is slow, resulting in a slightly lower temperature in the middle (pre-baking);

3) Different dye properties: due to the low temperature in the high side and the low side, the color fixing conditions are different; the low temperature type will have the medium shallow side and the dark side, but the high temperature type disperse dyes are the opposite; overcoming methods: first, improve the uniformity of fabric drying; second, Adopt uniform rolling mill; thirdly, improve the uniformity of rolling liquid; thirdly, use dyes reasonably when dyeing

3. Front and back color difference

1) The difference in the hardness of the rolls is too large;

2) The temperature and air volume of the front and back sides are inconsistent during pre-baking;

3) The effect of hot air pre-drying is poor and the humidity is excessive;

4. The difference between the left and right pairs of characters (essentially a localized front and back color difference)

1) During pre-baking, the left and right heat is uneven, and the radiation intensity is different;

2) The amount of air spray is uneven;

3) The heat dissipation of the left and right ends of the metal guide roller is different

4) Overcoming method: find the root cause from the device;

5. Front and rear color difference

1) Grey fabrics: changes in fiber type, quality, and cotton blending; (cotton blending is different, or the factory uses the wrong yarn)

2) Treatment before training and bleaching

A. The equipment used for pretreatment is different, the process conditions are not easy to master, and the color of semi-finished products is different after dyeing;

B. If the desizing effect is different, the color depth will also be formed;

C. Heat setting speed and wind speed;

D. pH value after mercerization: the most significant cause;

3) Dyeing

A. The dry moisture of the fabric is inconsistent before entering the baking oven;

B. The melting temperature is the most significant factor affecting the color difference in the dyeing process;

C. Inconsistent control of vehicle speed, dye solution, color developing solution, and reducing solution concentration, resulting in different color matching before and after;

D. Dyes with different origins and batch numbers have different shades;

6. Color point

(1) Morphology: irregularly appearing on the fabric with darker and finer points, generally occurring on light-colored fabrics;

(2) Causes

1) Improper selection of dyes, large particles, and coagulation;

2) Poor dissolving of dyes, use of hard water, etc.;

3) The dyeing equipment is not clean;

4) Poor management, improper storage and use of dyeing materials;

5) Environmental factors

7. Improper control of raw material factors and processing conditions

(1) After pad dyeing, it is dipped on the dryer and the wool fiber is brought to the fabric to finally form a color point; (neps)

(2) Polyester has fuzz melted in singeing, when dyeing, it absorbs color into black spots;

(3) Ways to overcome

1) Increase the number of dyestuff grinding and appropriate amount of dispersant to prevent agglomeration;

2) To ensure good solubility of dyes, use soft water. When disperse dyes are dissolved, the water temperature should not be higher than 50 degrees Celsius;

3) When changing the dyeing color, especially when the color is dark to light, wash the dye tank and pipes;

4) The barrel must be washed before use;

5) Pay attention to the cleanliness of the production environment;

6) Do a good job of cleaning the drying cylinder;

8. When singeing, it is necessary to control the singeing flame, vehicle speed and other factors, and strengthen the bristles;

9. When applying emulsified wax softener, pay attention to the formula.

10. Deep and shallow edges

(1) Status: deep or shallow selvedge

(2) Causes

1) It is related to the structure of the selvage itself: the selvage is thick, with a lot of liquid, and the color is dark;

2) It is related to the performance of dyestuffs, it is sensitive to humidity, and the dyeing rate is different during color matching, resulting in deep edge defects;

3) It is related to the condition of the dyeing equipment: the fabric with thicker selvage is easy to grind the roller into a concave shape in the selvage part, forming a shallow edge;

4) It is related to the pre-dyeing treatment: the mercerizing expanded fabric edge is not washed enough, and the washing alkali is not clean, resulting in a deep edge or a shallow edge;

5) It is related to the curling of the jigger: the curling is uneven, the exposed part is exposed, and a deep edge is formed;

6) It is related to the temperature of cloth clips and needle clips;

11. Weft skew

(1) Form: the warp and weft yarns of the fabric are not perpendicular to each other or the weft yarns show an irregular curve shape;

(2) The basic reasons for the weft skew

1) The seam of the grey fabric is bad;

2) The tension of the fabric is uneven during processing;

3) "Partial open width" produced in the process of rope processing;

(3) Forms, causes and overcoming methods of weft skew

1) Straight line weft skew or unilateral partial weft skew with different methods on the left and right;

2) Horizontal arc weft and oblique of different sizes;

3) Irregular local weft skew.

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