The use of screen printing patterns on dark clothing is generally a bit different from the original. If you use the discharge ink to show the characteristics of the pattern. Discharge printing, for the screen printing industry, may bring about a technological revolution. In the screen printing industry, there are two views on whether to approve printing or not. The discharge printing process uses a specific fiber dye to discharge the cloth according to a chemical reaction, and a white or cloth natural color and various colors can be displayed in a printed pattern area. Discharge ink is used for printing dark fabrics. The dye discharge agent in the ink decomposes the dye in the printing area under the condition of heat and forced air, and finally leaves the molecular composition of the ink on the fabric.
With discharge inks, screen printing can be performed on dark fabrics and colorful prints can be printed. Dispensing printing completely eliminates the need to use a plastic melt ink to lay a foundation on a cloth.
There are two arguments for denying printing: 1) People have become accustomed to using plastic melt inks; they can also print colorful patterns on cloths; 2) Discharge agents contained in dye discharge inks contain formaldehyde and lead-substances, and they are healthy when they are used. Harmful.
Therefore, the screen printing operators should be trained to use the discharge ink correctly to eliminate the harm to the body. The main problem is that in the dryer, formaldehyde, lead, and sulfur dioxide are generated during the heating and drying process due to the discharge ink. The countermeasure is to use a forced air dryer to discharge harmful gases within the operating range. The best method is to test the quality of the workshop air. The values ​​of formaldehyde and lead in the air are specified in the range of 0.75 ppm. If sufficient and effective exhaust devices are used in the workshop, almost all the volatile gases emitted by the discharge ink will be discharged outside.
Preparation before discharge printing
1. Prepare discharge ink. The ink includes: bases, pigments, active agents, other additives. Stir the above ingredients thoroughly. The quantity to be dispensed must ensure the amount of one-time printing. When adding the active agent, it must be done according to the manufacturer's measurement and deployment instructions. Otherwise, the discharge effect will not be generated, and the pattern will not have a vivid effect. After the deployment of the discharge ink effective time is 8h, after the operation of the discharge ink must be properly handled, can not easily be discarded. Printing discharge ink must use water-resistant photosensitive adhesive screen.
2. Prepare clothing for printing. Not all fabrics are suitable for printing. Cotton/polyester blended fabrics are not suitable for the discharge process. The color dyes on these fabrics are different. When the fabrics are discharged, the non-uniform bleaching effect will occur due to the different dyes.
In order to get the most vivid and uniform printing effect, 100% cotton cloth should be used. The fabric should be increased in the bleaching process before dyeing in the manufacturing process, and printing with plastic melt ink does not require this process. Therefore, the appearance of discharge printing has also promoted the development of garment manufacturers suitable for discharge printing (special handling). If you use a 100% cotton cloth that has not been bleached beforehand, it is not appropriate to use a discharge dye.
Printing color patterns on the discharge area of ​​ordinary cotton T-shirts will affect the discharge fibers after printing. Therefore, the color of each batch of dyeing cloth must be considered. The only way to print a fine-lined color pattern is to use bleached cotton cloth.
printing art
Dip printing ink printing method is very simple. The printing pattern is the same as the plastic melt ink and the water-based ink printing method. The printed cloth is sent to the dryer. The special point of using a discharge ink that is difficult to print is that the printed pattern is not visible to the eye when the printed cloth is removed from the printer, and the pattern is visible only when the printer comes out of the dryer. an examination. Scraps printed cannot be checked before the drying process. This has also been the reason why some clothing printers do not use discharge inks.
If a printer does not use water-based inks and is accustomed to using plastic melt inks, he may stop printing for a while during the printing process. At this time, the discharge ink placed on the screen will dry rapidly, causing the screen to fail. Printed results.
It is important to ensure the proper drying temperature for discharging the ink. In other words, only the proper drying temperature can ensure the drying of the discharged ink. In addition, sufficient air flow in the dryer and complete evaporation of moisture from the fabric are also important conditions. After printing, a sample flush test can be performed on the discharged print. Appropriately dried discharge dyes have excellent resistance to washing and dry cleaning. For pattern dyeing of decorative fabrics, the pattern can be straightened with an iron.
As long as the fabric printer has mastered the common sense of using a discharge ink and has some experience in the screen printing process, he can print a very beautiful print pattern.
Source: China Polymer Network