Precautions For Continuous Dyeing Of Webbing

1. The raw material of the ribbon should first pay attention to whether the yarn used is from the same batch, because the "oil" content of different batches of yarn is not the same. If blended, it will become a factor in the color of the dyeing process; Secondly, has the raw material undergone pre-treatment? The refined raw material has a very good dyeing effect because after treatment, the "oil" on the yarn is removed and the dye can directly come into contact with the fiber for dyeing, without protection.
2. The pressure of the cylinders at both ends of the dyeing tank (also known as rolling mill, dyeing tank, dyeing machine) roller is uniform. The rolling mill of the continuous hot-melt dyeing machine for woven belts generally uses pneumatic pressure, with one cylinder on each side of the roller. After the rolling mill runs for a period of time, due to the effect of moisture in the compressed air, there will be a difference in pressure at both ends of the cylinder, resulting in uneven liquid carrying rate of the billet and producing color difference in the edges. In addition, the two ends of the rolling mill rolls are pressurized, causing a certain degree of deflection, resulting in inconsistent rolling allowance rates between the edges, and also causing color differences in the left, middle, and right directions.
3. The pressure, concentricity, and hardness factors of the dyeing groove roller are important in production. To minimize the impact of roller pressure on left, middle, and right color differences, it is generally recommended to control the roller pressure at 0 during ribbon dyeing Above 2MPa. Due to the wear and tear of the rolling mill rolls during the production process, it is required to regularly calibrate and repair them, otherwise it is easy to cause uneven rolling residue and color due to the lack of concentricity of the rolling mill rolls. The residual rate obtained by rollers with different hardness varies. If the hardness is too high, it may lead to insufficient absorption of dye, while if the hardness is too low, it may cause excessive residual rate, resulting in a large amount of dye migration and color production. The appropriate hardness should be determined according to the strip.
4. The effect of infrared pre drying temperature on woven tape: After pre-treatment and immersion in dyeing solution, polyester woven tape generally needs to undergo infrared (wire) pre drying treatment before entering the color box to prevent dye migration during the drying process, avoid color spots and color differences between the front and back sides. When the infrared pre drying temperature is below 80 ℃, the color difference between the front and back of the ribbon is significant, making it difficult to meet the customer's usage requirements. When the infrared pre drying temperature reaches 100 ℃ or above, the color difference between the front and back of the woven tape is greatly improved. This is because when the pre drying reaches above 100 ℃, the moisture in the woven tape is basically evaporated, greatly reducing the possibility of dye migration. Considering dyeing production practice and energy consumption, it is more appropriate to control the infrared pre drying temperature between 100 ℃ and 150 ℃. In production, it is generally determined based on the thickness and liquid content of the billet and strip variety. The higher the liquid content of the billet and strip, the higher the infrared pre drying temperature. In actual production, it is not enough to rely solely on infrared pre drying temperature to control the color difference between the front and back of ribbon dyeing, especially for sensitive colors such as coffee and dark green. It is necessary to use anti swimming agents and other additives in combination to achieve good dyeing results.
5. The effect of curing temperature in baking oven on color development. Baking color development is an important component of continuous solution dyeing, and the uniformity of curing temperature in baking oven plays a key role in controlling the left, middle, and right color difference of woven tape. After infrared pre drying and entering the baking oven, it is necessary to ensure consistent temperature for polyester ribbon, otherwise significant color difference will occur. The experiment shows that when the temperature difference between the left, middle, and right sides of the baking oven exceeds 2 ℃, the color of the woven tape changes significantly. So, during dyeing production, it is necessary to ensure that the baking oven temperature is uniform.