1 The influence of semi-finished products
In the production process of dyed cloth, the performance of semi-finished products is crucial to the color consistency, color stability and color difference adjustment of the colored cloth. Semi-finished products require uniform pre-treatment, and slight changes in the processing conditions of semi-finished products will be reflected in the dyeing color. In production, some orders have large batches. Even if they are of the same variety, the quality of semi-finished products may be different due to differences in gray fabric origin, sizing type, sizing rate, cotton quality, cotton blending, and textile production processes. Therefore, in production, each process must be strictly controlled, and the process control indicators of each process of scouring and bleaching must be measured in a timely manner to maintain consistent process conditions. Large batches need to be produced with samples, and if the difference is large, the prescription must be adjusted in time to avoid large changes in color difference before and after production, resulting in repairs and increased consumption. In order to reduce the impact of semi-finished products on the dyeing rate, a reasonable scouring and bleaching process should be formulated. For the same type of fabric, especially for returned orders, the machine must be designated and produced with mature technology to improve the dyeing reproducibility of the original order prescription.
2 Influence of the Dyeing Process
2.1 Effect of Selection of Dyes and Auxiliaries on Color Difference
2.1.1 Dyes
When using Shilin dyes for dyeing, some dyes may remain in the dyeing tank due to their slow dyeing rate. In the middle deposition, the color light of the dyed cloth gradually approaches the color light of the dye with a slow dyeing rate, causing color difference between the front and back. Therefore, when producing olive green, Shilin yellow is often used. In order to stabilize the color, we use Shilin olive green or grass green. In addition, in order to prevent dye deposition, dispersants can also be added to the dye to make the dye liquid in the material tank and trough more uniform and prevent aggregation, thereby effectively improving color difference and reducing costs.
When using reactive dyes for dyeing, due to the high reactivity of reactive dyes, if the performance gap between the dyes is large, the color and light are difficult to control during continuous pad dyeing, and color differences between front and back are likely to occur. Therefore, dyes with consistent or close compatibility should be used during the production process.
2.1.2 Additives
Additives have a significant impact on the color difference and flowering of edges. Adding appropriate additives can effectively improve color differences and streaks caused by gray fabrics, equipment, etc. However, sometimes the addition of certain additives cannot simultaneously solve many problems such as color differences and stripes. At this time, only by re-selecting dyeing materials and using additives with better effects can we produce products that satisfy customers.
For example, adding anti-migration agents during production can improve dye migration caused by uneven air room and drying temperatures, and is beneficial to the adjustment of color difference; however, it cannot effectively improve fabric defects and cotton impurities. , neps. Dead cotton. Defects such as weaving strips cause the dyed cloth to be uneven and not full. Therefore, when the quality of gray fabric is poor, using leveling agent will have better effect. However, it is difficult to adjust the color difference when using a leveling agent, and the color difference in the edges is heavier than when using an anti-migration agent. For example, when producing gray polyester-cotton, adding an anti-migration agent will result in better color difference control, but the fabric surface will be uneven; using a leveling agent, the fabric surface will be better, but the color difference will not be well adjusted. At this time, you can choose two prescriptions, dispersed black or dispersed gray, according to different gray colors, so that the color difference can be controlled at 4.5 levels.
2.2 The impact of priming process on color difference, stripes and color strips
In production, the dyes in the trough have different affinities for fibers due to different Rf values. Those with high affinity have a fast dyeing rate, while those with low affinity have a slow dyeing rate. When the dyes are mixed together, the fiber will take away various colors. Dye components are different, which can easily lead to head-to-tail color difference. If the dye solution is constantly replenished in the trough, the components of the dye solution in the trough will gradually reach a dynamic balance, and then the color difference will gradually stabilize. This is the main reason for inaccurate color testing and unstable color heads at the beginning. , the lighter the color, the longer it takes to reach equilibrium; the darker the color, the shorter the time it takes to reach equilibrium. The capacity of the trough should be small, which will help the dye solution reach equilibrium in a shorter time and help stabilize the color. For the color difference at the beginning of the car, you can use the method of diluting or adding lake to make up for it. For example, when producing light blue, as the dyeing progresses, the color becomes lighter and lighter, and the red light increases. If the initial driving trough is diluted, the color difference between the head and the tail will be reduced; while when producing dark blue, the color developing solution is used. Add color lake to solve the color difference before and after.
The drying equipment on the primer produced by our factory is divided into three parts: infrared and drying room dryers. The infrared effect is good, the dye migration resistance is small, and the color difference is small; the air volume in the drying room should be moderate. If the temperature is too high, it will easily cause streaks. If the temperature is too low, add a medium drying load. The first section is 60 ~ 70℃, and the second section is better. When the temperature is 90 ~ 100℃, it is beneficial to leveling dyeing.
The dryer is an auxiliary equipment and cannot dry the fabric directly. It will cause serious dye migration, forming a yin and yang side, resulting in false color difference, which is not conducive to adjusting the color difference when rolling. The dryer should be dry and dry, but not too hot. For example, when producing bright blue or gray, the color light is sensitive. If the drying temperature is too high, the temperature in the middle of the drying cylinder will be inconsistent. The middle temperature will be high, the dye will develop color, and the dark green light will be bright; Forming false chromatic aberration. At this time, if pressure is added due to the depth in the middle and the pressure is reduced due to the shallow depth on both sides, the color difference will become more and more serious. At this time, the operator must not only be experienced, but also have an understanding of dye performance. For example, when producing light blue, due to the color development of the drying part, when the base is adjusted to have almost the same color depth, the color difference will be 2 to 3 levels after continuous machine removal; but when the base is adjusted to have the left, middle, and right colors close to each other, it will appear darker in the middle. , the color difference will be 4~5 levels after continuous disembarkation.
2.3 The influence of baking machines on color difference and color bloom
Most of the existing equipment in China are old models from the 1980s. The circulating fan equipment is prone to uneven air volume, and the large box volume makes the baking The temperature difference between the sides of the roasted chicken is large, resulting in color difference.
You can adjust the air volume and direction of the air nozzle, or adjust the pressure of the bottom rolling machine to compensate for the color of the tea caused by the difference in baking temperature. The temperature should be stable and consistent during the production process to prevent color differences from front to back.
2.4 The influence of color soap cooking on color difference
In production, the temperature of the reduction steamer must be above 100°C, and the pressure should be consistent and uniform, otherwise streaks will occur. By installing a U-shaped pressure gauge in the box, the pressure in the steamer can be intuitively and accurately controlled. It can also prevent batch errors caused by different immersion times and unstable liquid amounts due to inconsistent feed troughs and liquid volumes. Right nowIn normal production, an appropriate amount of lake should be added to the rolling trough and liquid-sealed trough according to the fabric, hue, and depth to prevent changes in the dye concentration in the trough during initial turning and normal production. Because the dye padded onto the fabric during production will continue to dissolve into the sealing liquid and then be re-dyed onto the fabric from the sealing liquid opening. Only the amount of dissolved dye will be consistent with the amount of dye material re-dyed onto the fabric. When, dynamic balance can be achieved in the trough. When vehicle speed, temperature, and steam pressure change, this balance will fluctuate, causing front and rear color differences.
Table 1 The ratio of lake addition amount and dye dosage
|——————————– ——|
|Pure cotton fabric| Add lake/L |% of dye usage |
|———|——— —|—————|
|Extra light color| 0 | — |
|———|– ———-|—————|
|Light color| 2-4 | 0.5-1% |
|———|————|—————|
|Medium color| 4-6 | 1-1.5% |
|———|————|——— ——|
|Dark| 6-10 | 1.5-2.5% |
|———|————| —————|
|Extra dark color | 10-15 | 2.5-4% |
|————————————- -|
|Thin fabrics generally add more color than thick fabrics|
|——————————— ——–|
|Pure cotton fabric| Add lake/L | % of dye used |
|———|——- —–|—————|
|Extra light color| 0 | — |
|———|————|—————|
|Light color | 1-2 | 0.25-0.5% |
|———|————|————- –|
|Medium color| 2-4 | 0.5-1% |
|———|————|—————|
|Dark| 4 -8 | 1-2% |
|———|————|————— |
|Extra dark color| 8-12 | 2-3.5% |
|—————————- ———-|
|Thick fabrics generally add more color than thin fabrics |
|————————————-|
In production, The amount of washing, overflow and spray water also has a great impact on the color light stability. Especially for reactive dyes, due to poor dye fastness, the size of the water flow, pH value and dye content will all cause changes in the color light during continuous production.
In addition, soaping conditions have a great impact on certain colors. For dyeing fabrics of these colors, special attention should be paid to the consistency of the soaping conditions. For example, blue series dyes such as brilliant blue and dark blue generally have poor soap boiling fastness, so dyeing materials with good fastness should be selected during production, which is very important for color and light stability. For example, when dyeing lotus purple, multiple prescriptions were compared and selected. Although the color test was normal and the color light changed little, the color light still fluctuated greatly during the actual production process.
The influencing factors of lotus purple in production are:
Vehicle speed: the faster the vehicle speed, the greater the red light; the slower the vehicle speed, the greater the blue light.
Baking temperature: 195℃, ideal and stable color difference and color. The higher the temperature, the greater the blue light; the lower the temperature, the greater the red light.
Spray overflow: The continuous shower overflow is large, the color is light, and the blue light is large; the shower overflow is small, the color is dark, and the red light is large.
Soap cooking: The temperature of the flat washing compartment has a great influence on the color and light. When the temperature is 90℃, the color will change little and the color and light will be stable; when the temperature is lower than 80℃, the color will appear dark blue after continuous use of the machine, and the color will change greatly after soaping twice. When the temperature is higher than 96°C, the color will be light and red after continuous unloading, and the discoloration will be small after soaping. It will not change color after two soapings.
Vapor solidification: When steam solidifying, the materials and techniques used must be consistent, and the concentration, temperature, and alkali content must be consistent.
2.5 The impact of post-finishing on color difference and color flowers
2.5.1 Choose finishing additives that have little impact on color and light
Because the greater the impact on color and light, the greater the impact of conditions during production, the production process It is unstable and will affect the consistency of front and rear color and the color difference between edges.
2.5.2 The finishing equipment is parked and the speed is unstable
It has a great influence on the color head change, and sometimes also affects the color difference in the edge; after tentering and pre-baking, the dryness and moisture in the left, middle and right are inconsistent, which can also easily cause color difference in the edge.
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