Continuous dyeing of ribbon

Continuous pad dyeing has become the most popular and effective ribbon dyeing process. So, what matters should be paid attention to in ribbon dyeing?

Matters needing attention in continuous dyeing of ribbons mainly include:

1. Ribbon blank factor Ribbon blank should first pay attention to whether the yarns used are of the same batch, because different batches of yarns contain different "oils", and if blended, it will become a factor of color in the dyeing process; Secondly, whether the grey cloth is pretreated or not, the dyeing and coloring effect of the refined grey cloth is very good, because the "oil" on the treated yarn can be removed from the dye and can be dyed directly with the fiber without any protection.

2. The cylinder pressure at both ends of the dye vat (or rolling mill, dye vat and dyeing machine) is even. The coiler of ribbon continuous hot melt dyeing machine generally adopts pneumatic pressurization, and there is one cylinder on each side of the drum. When the rolling mill runs for a period of time, due to the moisture in compressed air, the pressure at both ends of the cylinder will be different, resulting in uneven liquid carrying rate of the blank and color difference at the edge. In addition, the two ends of the roll of the rolling mill are compressed, which produces a certain deflection, resulting in inconsistent edge residual rate and color difference on the left, middle and right.

3. Factors such as pressure, concentricity, hardness, etc. In order to minimize the influence of rolling pressure on the left, middle and right chromatic aberration, the rolling pressure should generally be controlled above 0. Ribbon dyeing 2MPa. In the production process, due to the wear of the roll, it is necessary to calibrate and repair the roll regularly, otherwise the eccentricity of the roll will easily lead to inconsistent residual quantity, which will lead to discoloration. Rollers with different hardness have different residual rates. Too hard may lead to insufficient dye absorption, and too soft may lead to a large number of dyes migrating to produce color. The hardness depends on the strip.

4. Influence of infrared pre-drying temperature on ribbon. After pretreatment and padding with dye solution, polyester ribbon is generally pre-dried with infrared rays (wires) before entering the color box, so as to prevent dye migration during drying and avoid dyeing defects such as streaking and color difference between front and back. When the infrared pre-drying temperature is lower than 80℃, the color difference between the front and back of the ribbon is large, which is difficult to meet the customer's requirements. When the infrared pre-drying temperature reaches above 100℃, the color difference between the front and back of the ribbon is greatly improved. This is because when the pre-drying temperature reaches above 100℃, the water in the ribbon basically evaporates, which greatly reduces the possibility of dye migration. Considering the dyeing production practice and energy consumption, it is more appropriate to control the infrared pre-drying temperature at 100℃- 150℃. Generally, the yield depends on the thickness of the blank and the liquid carrying rate. The higher the liquid content of the blank, the higher the infrared pre-drying temperature. In actual production, the color difference between the front and back of ribbon dyeing can not be controlled only by infrared pre-drying temperature, especially for sensitive color numbers such as coffee and dark green. Only the cooperation of additives such as anti-migration agent can achieve good dyeing effect.

5. The influence of oven fixing temperature on hair color is an important part of continuous hot melt dyeing, and the uniformity of oven fixing temperature plays a key role in controlling the left, middle and right color difference of ribbon. The polyester ribbon is pre-dried by infrared rays before entering the oven, so the temperature must be consistent, otherwise there will be obvious color difference. The test shows that the temperature difference between the left, middle and right of the oven exceeds 2℃, and the color of the ribbon changes obviously. Therefore, in the dyeing production process, the oven temperature must be uniform.

6. The influence of water content on the left, middle and right chromatic aberration of ribbon. A certain amount of oil will be added in the spinning process of polyester filament, so deoiling treatment should be carried out before dyeing. Ribbon is usually dried after dyeing pretreatment. Uneven surface temperature of the drying cylinder will cause the difference of water content in the blank, and in serious cases, it will cause the left, middle and right color difference of ribbon. In the dyeing production process, in order to avoid the left, middle and right color difference caused by the different moisture content of the blank belt, it is necessary to ensure that the blank belt is thoroughly dried before dipping in the dyeing solution, and the drying cylinder is regularly overhauled.

7. Other factors causing color difference As far as production management is concerned, the main factors affecting the left, middle and right color difference of polyester ribbon dyeing are as follows.

(1) There are many differences in fabric texture, warp and weft density, warping tension and thickness, which will cause dyeing color difference. Due to the difference in production efficiency between looms and dyeing machines, the blanks produced by different looms are dyed in the same dyeing machine, and even when different batches of ribbons are dyed in the same dyeing machine, color difference will occur. In order to minimize the influence of the quality difference of the blank belt on the dyeing color difference, it is required that weaving and dyeing must coordinate the production plan as a whole, and at the same time, do a good job in the inventory management of the blank belt and try to be "first in, first out".

(2) The oven under the management of the machine should be regularly overhauled and maintained to ensure the normal operation of heating equipment (such as heating pipes and burners), normal temperature rise and temperature control. In the actual production process, it is also necessary to keep the air duct in the box unblocked and the filter screen clean. The belt feeding device of dyeing machine is very important to adjust the tension of grey cloth belt. Before entering the dyeing tank, the tension of the blank belt should be basically the same to ensure the consistency of its liquid carrying rate and color consistency. It is also important to control the tension exerted by the dyeing machine on the webbing. Because the ribbon dyeing machine generally adopts frequency conversion control to adjust the tension of the whole dyeing machine, it is necessary to ensure that the frequency conversion control signals of each working point are normal and repair the faulty equipment in time.

(3) The compatibility of dyes has a great influence on the color difference between the front and back of the ribbon. When different formulas produce the same color number, the color difference between the front and back of the ribbon is very different. Generally, sublimation fastness is selected to be compatible with disperse dyes of the same type or similar types (S, se, E), and the dyeing effect is good. In addition, the auxiliary use of anti-migration agent, penetrant and leveling agent also plays a role in controlling dyeing color difference, but it needs to be used reasonably.

To sum up, we should pay attention to the following points in our daily life:

(1) Roller pressure, uniformity of fixing temperature in the oven, infrared pre-drying temperature, moisture content and mass concentration of anti-migration agent will all affect the color difference of continuous hot melt dyeing of polyester ribbon. In general, the rolling pressure is 0. 2MPa, the temperature difference between the left and right oven is less than 2℃, the infrared pre-drying temperature is 100℃, and the mass concentration of anti-migration agent is less than15g/l; The pre-treated blank tape should be fully dried to effectively control the color difference of ribbon dyeing.

(2) The quality of green belt, machine management and dye formula also have important influence on the control of dyeing color difference. In the hot melt dyeing process of polyester ribbon, it is necessary to systematically control the consistency of grey fabric quality, do a good job of machine maintenance and repair in time, and use dyes and auxiliaries reasonably to obtain good dyeing effect. 1. About color difference

Typing samples and guest samples

Material and batch number: reflected colored light

Organizational form and density

Dyeing process differences: methods, dyes

Dyed bulk goods and confirmed samples

Transverse chromatic aberration between strips

Longitudinal color difference between each strip

Machine and its state difference

Color difference between dyeing batches

2. About color fastness

Color fastness is one of the important quality indexes of textiles. The so-called color fastness refers to the degree to which the color of dyed textiles remains unfading under the physical and chemical effects, that is, the degree to which the color of dyed textiles is influenced by the outside world is called color fastness. The color fastness is expressed by the color change of the sample after the test and the evaluation grade of the staining degree of the white cloth.

Among all kinds of color fastness, the most commonly used color fastness at present are rubbing fastness, perspiration fastness, washing fastness, light fastness, soaking fastness, brushing fastness and weather fastness. In real life, which items are tested mainly according to the final use of the product, among which the color fastness to perspiration, dry rubbing and immersion are the items required by the basic safety technical specifications of textiles, and all dyed textiles should be tested. In addition, the color fastness to saliva of baby textiles should also be evaluated.

Color fastness is generally evaluated by visual inspection, that is, the original discoloration of the sample and the staining series of white cloth are determined by comparing the gray card with the sample under certain lighting and environmental conditions. Grey cards (discoloration and dyeing respectively) have five fastness grades, which are 5, 4, 3, 2 and 1. Grade 5 is the best, and grade 1 is the worst. Every two levels add half a level, that is, 4 5, 3 4, 2 3, 1 2, so the gray card we use every day is 5 levels and 9 levels, and the evaluation result of dyeing fastness is one of 9 levels. If the color fastness of ribbon products can't reach the standard level, then ribbon products are unqualified.

The following ribbon standards must be met by ribbons:

1. The washing fastness was above 3.5, and passed the test standard of ISO105-C01:1989.

2. The rubbing fastness is above 3.5, and it has passed the test standard of ISO105-X12:1993.

3. The light fastness is above Grade 4, and it has passed the test standard of ISO 105-B02: 1994.

3. About color light sources

Textiles go through many processes in the production process. In this process, due to errors caused by raw materials, production technology, operation and other reasons, different batches or even the same batch of fabrics often have differences in color. If the color light source, color environment and color time are different, the evaluation of color difference is also different. Therefore, in order to accurately evaluate the color difference and ensure the consistency of color matching results, the customer-specified light source must be selected in the standard color matching light box to avoid visual differences caused by nonstandard or different light sources.

4. Classification of color light sources

D65:

International standard artificial natural sunlight source with color temperature of 6500K K k.

CWF:

Cold white fluorescence, 4 150K, American shop light source, commonly used color matching light source by American merchants.

TL84:

Cold white, with a color temperature of 4000K, is a common color light source for European and Japanese merchants.

F/A:

Yellow light source, light color reference light source, suitable for family or hotel room to observe color instead of light source.

Ultraviolet rays:

Ultraviolet light with a wavelength of 365 nm is used to detect whitening agents or fluorescent dyes on fabrics.

U30 (TL83):

Warm white light with a color temperature of 3000K, another American commercial light source.

Application of Ribbon: industrial hoisting of automobile seat belts and clothing, shoes and hats, bags, toys, handbags, handicrafts, automobiles, sporting goods, medical devices and other fields.