Ribbon continuous dyeing precautions
1. Ribbon raw material factor. The webbing of the webbing should first pay attention to whether the yarns used are of the same batch, because different batches of yarns contain different “oil” conditions, such as blending, which will become a factor in the dyeing process; secondly, whether the billet is pretreated After the refining treatment, the dyeing effect of the raw material is very good, because the “oil” on the yarn after the treatment is removed, the dye can be directly contacted with the fiber, and there is no protection.
2. Uniform factors of the pressure of the cylinders at both ends of the dyeing drum. The rolling mill of the continuous hot melt dyeing machine of the webbing is generally pneumatically pressurized, and each side of the roll has a cylinder. When the rolling car runs for a period of time, due to the action of moisture in the compressed air, the pressure at both ends of the cylinder will be different, resulting in uneven liquid flow rate of the blank belt, resulting in a side chromatic aberration. In addition, the rolling ends of the rolling mill are pressurized, resulting in a certain degree of deflection, resulting in inconsistent rolling margins in the edges, which also causes left and right chromatic aberration.
3. The pressure of the dyeing roller and the concentricity and hardness factors. In the production, the pressure of the roll should be controlled to a minimum of 0. 2MPa or more. In the production process, due to the wear of the rolls, it is required to periodically calibrate and repair the rolls, otherwise it is easy to cause the color difference due to the inconsistency of the rolling rolls due to the different hearts of the rolls. Rolling mills with different hardnesses have different rolling ratios. Too hard may result in insufficient absorbing dyes. Too soft may result in too much residual ratio, resulting in a large amount of dye migration and color formation. How much hardness is required depends on the strip.
4. The effect of infrared pre-baking temperature on the webbing. After the pre-treatment and padding dyeing process, the polyester webbing is generally subjected to infrared pre-baking treatment before entering the color-developing box to prevent the dye migration phenomenon during the drying process, and to avoid dyeing of the color flower and the color difference between the front and the back. When the infrared pre-baking temperature is lower than 80 °C, the color difference between the front and back of the webbing is large, and it is difficult to meet the customer’s use requirements. When the infrared prebaking temperature reaches 100 ° C or more, the chromatic aberration of the front and back of the webbing is greatly improved. This is because when the pre-baking reaches 100 ° C or above, the moisture of the webbing is substantially evaporated, which greatly reduces the possibility of dye migration. Considering the dyeing production practice and energy consumption, the infrared pre-baking temperature control is more suitable at 100 °C-150 °C. In production, it is generally determined according to the thickness and liquid carrying rate of the blank strip. The higher the liquid carrying rate of the billet, the higher the infrared pre-bake temperature. In actual production, it is not possible to rely solely on the infrared pre-bake temperature to control the color difference between the front and back of the ribbon dyeing, especially the sensitive color numbers such as coffee and dark green. It is necessary to use the combination of anti-migrator and other additives to achieve a good dyeing effect.
5. The effect of the fixing temperature of the baking box on the color development. Baking hair color is an important part of continuous hot-melt dyeing. The uniformity of the fixing temperature of the baking oven plays a key role in controlling the left-right color difference of the webbing. After the polyester webbing is pre-baked by infrared light and then enters the baking oven, it is necessary to ensure that the temperature is consistent, otherwise a significant color difference will occur. Tests have shown that the difference in temperature between the left and right of the baking box exceeds 2 ° C, and the color of the webbing changes significantly. Therefore, the dyeing production must ensure that the temperature of the baking oven is uniform.
6. The effect of moisture content on the left, middle, and right color difference of the webbing. Polyester filaments will be added with a certain amount of oil during the spinning process, so they must be degreased before dyeing. The webbing is generally dried after pre-dyeing, and the uneven temperature of the surface of the drying cylinder may cause a difference in moisture content of the billet. In severe cases, the left-right color difference of the webbing may be caused. In the dyeing production process, in order to avoid the left-right color difference caused by the different moisture content of the green strip, it is necessary to ensure that the billet is thoroughly dried before the padding dyeing liquid, and the drying cylinder is regularly inspected.