In recent years, the demand for dyeing and finishing of knitted fabrics has increased. In order to expand the market, woven printing and dyeing companies have also made efforts to improve equipment, processes, and management to meet the production and processing requirements of such products. Our company has achieved the production of knitted fabric printing through continuous efforts, and the output is increasing month by month, but it is not easy for factories that are used to printing woven fabrics to adapt to the production of knitted fabric printing. It is inevitable in the production process There will be many problems. The common defects and preventive solutions in production are discussed as follows.
1. How many hairs of knitted semi-products are easy to cause printing defects. Printing of knitted fabrics is more common because of the more hairs of semi-products. This is because the pre-treatment process of knitted fabrics and woven fabrics is different. Knitted fabrics are not burned. Compared with mercerizing treatment, and the fabric is relatively loose, it is generally pre-treated in the overflow cylinder. Compared with woven fabric, it is easier to fluff, and it is easy to plug the net when the hair head is printed more. Solution:
(1) Strengthen the quality inspection of semi-finished knitted fabrics. For semi-finished knitted fabrics of inferior quality, customers should be notified in time to agree on treatment methods.
(2) When setting semi-finished products, consider adding a bristle device, air blowing device, etc., and remove the cloth hair by mechanical means.
(3) The cloth feeder of the printing machine strengthens the dust suction device, and installs several sticky nets on the printing machine, which can stick most of the hairs.
(4) Adjust the process in time and increase the number of washing times to minimize the hairs as much as possible.
(5) The use of polishing enzyme additives for polishing treatment, but because the cost and risk of such treatment is relatively large, we are currently only in the sample stage, not promoted.
2. Holes in finished knitting and printing products The holes in knitting and printing products may come from three possibilities: improper pre-treatment process during the processing of semi-finished knitted products, causing bleaching holes; hooking and hooking or opening in the washing process of the cylinder The speed of the machine is too fast, causing mechanical scratches, etc .; the cloth pusher is not clean, there are debris such as bamboo clips, which are mixed into the cylinder and caused to break. Solution:
(1) Carefully inspect the quality of the incoming fabric. If there is a grey cloth with many neps impurities, broken yarns or many yarn joints, the customer should be notified in time to deal with them, because these problems are the root causes of the holes in the grey cloth, and timely notification Pre-processing should be adjusted accordingly. If there is a hole in the original billet, it must be prevented from flowing into the next one.
(2) Choose a machine cylinder with smooth inner wall and good running performance to process the knitted fabric, and the long-car washing rope-shaped cylinder should be kept clean and smooth.
(3) To improve the operator's responsibility, the car turning over the grey cloth should be cleaned, and the debris such as bamboo clips and iron nails should be prevented from being entrained, and the cleaning work of the cloth pusher should be strengthened. After the printed cloth is washed, the speed of the opening width should be appropriate to prevent the accident from happening too fast and the mechanical damage caused by the time.
3. The problem of insufficient weight of knitted products Generally speaking, customers are more particular about the weight of knitted fabric products. It is also an important issue for printing and dyeing enterprises to do a good job in the quality of knitted fabrics. Can the weight be stable and the weight can reach customers? The requirement is an important factor for printing and dyeing enterprises to gain a foothold in the knitted product market. In order to ensure the weight of each batch of knitted products, the following measures need to be taken:
(1) To check the quality of the grey cloth, generally the gram weight of the grey cloth can meet the gram weight requirement of the finished product, but if the gram weight of the semi-finished grey cloth does not meet the predetermined requirements of the gram weight of the finished product, it is difficult for the finished product to meet the gram weight requirement. Therefore, the gram weight of the semi-finished product is very important. It is generally required that the gram weight of the semi-finished product be measured before and after the predetermined type, so as to have a pre-estimation of the gram weight of the finished product after processing.
(2) The grey cloth with spandex should be pre-formed in advance, so as to stabilize the gram weight of the finished product.
(3) For the products that do not meet the standard, the factory will first analyze the reasons by itself, and then try to change the process and operation. For example, if the total weight of the cotton spandex comes to meet the requirements of the finished product, but it is often difficult to meet the expected basic weight of the grey cloth after the reservation. This is limited by the performance of the machine and related to the characteristics of the grey cloth. Predetermined grammage is quite difficult. We have modified the process based on previous experience and practice, heating water in the rolling groove for pre-determined molding, which has a certain effect on the stabilization of grammage, and sometimes meets the customer's grammage requirements .
(4) Reasonable selection of mechanical equipment, technological operation, dyeing and chemical additives. It is relatively common for machinery to fail to meet the standard due to its inherent tension and other properties. Therefore, the setting machine for knitting fabrics must be selected or appropriately modified. The temperature of the drying room is stable, and the performance of circulating blowing and overfeeding is better. The addition of steam jet devices on the front of the setting machine is also a measure to stabilize the weight. According to the characteristics of the grey cloth, formulating appropriate pre-treatment process also plays an important role in ensuring the weight, and it is necessary to choose and apply additives that have little weight loss to the fabric as much as possible. There are many varieties of pre-treatment aids with uneven quality. Some of the pre-treatment aids are too intense, and even hurt cellulose, causing unnecessary weight loss. Such aids should be avoided as much as possible. If the printing process can be accepted by the customer, it should be considered as much as possible to choose the coating printing process, which can achieve the purpose of stability and even weight gain.
(5) For shaping, consider using the best process to ensure the weight of the product. When finalizing the finished product, some additives such as urea can be added to increase the weight to compensate for the lack of fabric weight.
4. Anti-staining problem during washing.
Since the knitted fabric has not been mercerized, the dyes are likely to fall off and cause staining during the washing process, so the anti-staining requirements of the white ground are higher. So to do:
(1) The color of steaming should be sufficiently complete, so that the dye can be fixed as much as possible. If the steaming is not sufficient, the fixation of the dye and the fiber will be weak. The dye will easily fall off during washing, and the stain will become more serious.
(2) Fully compare and select the muddy reactive dyes, and choose excellent dyes with strong lifting power and high fixing rate to prevent sticking due to the poor performance of the dyes and easy dye shedding.
(3) Select and apply soaping agent with better anti-staining performance to minimize white ground staining. The floating color should be washed clean, less floating color will not be easily stained when soaping.
(4) The water elution paste should be thorough, the cloth surface can't be removed, the finished product feels too hard, and the effect of adding more softener is not good, and the cost of post-finishing increases, which will also cause defective products. Therefore, we must pay attention to the formulation of the process and standardize the operation during the washing operation.
There are still many problems encountered in the production of knitted fabric printing. The above only lists the most common types of defects and makes a superficial analysis. To produce high-quality knitted printed fabrics, it also needs the application of technology and equipment. Selection, management of operations, matching of color separation technology and other measures have been taken in many ways to produce a first-class product.
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