Practice of Knit Fabric Paint Printing (4)

3.2 Feel and fastness issues

To solve this problem, it is necessary to solve the contradiction between the feel and fastness of paint printing, and to find the best combination of high-quality, low-cost paint binders, colorants, thickeners, and additives. The core is to seek more excellent performance adhesives, after a number of comparative tests, and finally determined the "Super soft technology" based on the TYS super soft printing paste developed by the Zhejiang Silk Institute. Since 1998, with this process, more than 1,000 tons of knitted fabrics have been accumulated. In terms of fabrics, hand feeling, fastness, and bright color, all of them meet the export requirements of customers, except for a few that must be produced using reactive dyes. In addition, all other paints have been directly printed. The super soft technology we use is as follows:

Prescription: (The prescription is quite similar to TYS-2 printing paste of Zhejiang Silk Academy)

Super soft adhesive 8-18%

A state pulp 35%

Synthetic thickener 1 - 1.5%

Water Y

100%

(Appropriate amount of hand feel modifier added as needed)

Process: Rotary screen printing → 105 → 110°C pre-baking 2 minutes → 160°C baking 1.5 minutes → finished product

Explanation:

1. The paint colorant should choose high-quality varieties (such as German Dystar products). The high-quality paint color paste has a high particle content, and has a small amount when obtaining the same color depth, which is favorable for the improvement of the fastness of the finished product. At the same time, the heat-resistant, oxygen-resistant bleaching, chlorine-resistant bleaching performance is good, and high-temperature discoloration can be avoided. The color is also more brilliant than general products and can be comparable to reactive dye printing.

2, the choice of adhesive is the key. Super soft adhesive, with a soft and smooth feel, while having excellent fastness, according to the amount of paint color paste, the shade of color, the amount of adhesive in the range of 6-16%. When encountering dark-colored full-bottomed printing products (with a coating amount of 6-8% or more), when the adhesive reaches 16%, the dry rubbing fastness of the printed product is 3, and the wet rubbing fastness is 2 and often fails to reach. The requirements for export products can be increased by adding 4 to 5% of good fastness adhesives, and the dry and wet rub fastness can be improved by more than half a grade. If this is the case, add 0.3 to 0.5 appropriate chain extender. , Can achieve dry rubbing fastness to or close to four, wet rubbing fastness to 2-3 or nearly 3, to meet customer requirements.

3. Thickeners use a semi-emulsified paste process. Of course, the full emulsification paste process is more beneficial to the finished product, but it will have a certain impact on the cost-stability of the printing. At the same time, the amount of flue gas during production will be more severe, affecting the production workshop. surroundings. The use of semi-emulsified paste technology can give a good balance between finished product feel and fastness. Synthetic thickeners Due to the different brands, the thickening ratio is very different. The use of high-quality brands (such as thickeners such as Hit or PTP) can reduce the amount of thickeners and minimize the effect of thickeners on hand sensation.

4. Check the pH value of the cloth surface after pre-treatment. It should be neutral. If the cloth surface is acid or alkaline, the uniformity of the coloring of the printed fabric will be affected, and the fastness will be reduced. operating.

5, before the cloth printing is best not containing softener, otherwise it will affect the paint coloring and wet rubbing fastness.

6, knitted fabrics should be first edge, rotary screen printing machine will not curl when printing, will not be displaced in order to carry out multi-color printing on flowers.

3.3 The problem of flowers

Circular screen printing of knitted fabrics, the difficulty of the flower is greater than the shuttle fabric printing, in addition to the elasticity of the factors, its strong water absorption, easy to suction the pulp is also an important cause of difficulties in flowers. After pulping, especially after full screen printing, the knitted fabric shrinks rapidly due to water absorption, making it difficult for other nets that are behind. Therefore, in the analysis of patterns, the development of drainage technology should be more careful, especially the location of the full net should be carefully considered, as far as possible, put back. In order to ensure the accuracy of the flower, we should also pay attention to the following points: The width of the fixed width of the door before printing should not be too wide, generally about 103% of the finished door width; the tension of the cloth should be as small as possible, and the patch glue must be used, and the thickness of the patch glue should be Suitable, strong adhesion.

4 Other issues

Because knitwear is easy to absorb pulp, this issue should also be taken into account in other areas. When the pattern is stacked on the block surface and the block surface, the amount of the woven fabric considered is 0.2-0.25mm, and the knitted fabric should be reduced by 0.1-0.15mm to prevent excessive overlapping colors and the lines are also in the shuttle. The width of the fabric is further reduced by 0.1-0.15mm, and the widths of the two are basically the same. The paste should be thicker and the pressure of the squeegee should be smaller to prevent excessive penetration during printing.

The color paste should not be visible on the reverse side when printed. The choice of net mesh number: fine stem 125 mesh; small surface 100 mesh; large surface 80 mesh; gold silver powder 60-80 mesh;

5 Relaxation finishing process

After the knitwear has been stamped and shaped, it is generally not subjected to any other sorting. After quality inspection, the export product is shipped from the domestic market after it has been wrapped and sold. Garment clothing factory according to customer requirements, and then washing, sand washing, enzyme washing and then clothing, after such treatment, feel further improved, weight can be restored, generally can be restored to the rough fabric weight, the shrinkage rate can be Make sure it is less than 5%. In most cases, garments are not ready for direct garments after printing. Experienced garment factories do not cut pieces immediately after processing at the printing and dyeing plants. Instead, the bags are opened and the knitted fabrics are allowed to relax for at least 1-2 days in a natural relaxed state, allowing the knitted fabric to shrink naturally. Reduced shrinkage of knitted fabrics. The shrinkage rate of the printing and dyeing factories after finishing the processing is often between 5-7%, often failing to reach the customer's 5% requirement. After natural relaxation, the shrinkage rate drops to 4-5%. At the same time, due to shrinkage and regain, the gram weight is also slight. There is an increase.

In short, based on the excellent adhesives, it is matched with high-quality coating colorants and thickeners to form the best combination, and at the same time, reasonable pre-treatment of the grey fabrics, strict rotary screen printing processes and proper finishing processes, Can produce excellent paint printing knitwear, to achieve the purpose of coating imitation reactive dye printing.