Common defects in printing products - roller screen printing

Third, the common defects in roller printing

1. Scratch printing and knife-line printing (1) Form: The printed fabric exhibits a print mark that is parallel to the cloth edge and does not change, that is, a scratched print; the printed fabric shows a wavy line, that is, a knife-line print.
(2) Cause: The former is caused by the hard particles in the colorant scratching the surface of the cylinder, and the latter due to the hard particles in the colorant produced by the reciprocating motion of the blade. The reasons for hard particles may be:
1 There is foreign matter in the color paste.
2 The printing scraper, the feed roller, and the slurry washer are not clean.
3 Excessive friction between the scraper and the flower cylinder produces copper particles (when the flower cylinder is not chrome-plated).
4 The low solid content of the original paste is greater than the high solid content of the original paste.
(3) Preventive measures:
1 Color paste to be used after filtration.
2 Chrome is chrome plated to increase its surface hardness and increase its wear resistance and smoothness.
3 Add lubricant to color paste.
4 Appropriately increase the solid content of the original paste in the paste or select the original paste with a higher solid content.

2. Drag or raise the knife (1) Form: Run two deep continuous slivers on the cloth.
(2) Causes: There are foreign materials under the knife edge, such as threads falling from the fabric, particles of dried pulp in the color paste, etc. (3) Solution: Clean the scraper and flower cylinder or once again be honest.

3. Cover color (1) Form: The bare surface of the flower tube is covered with an undesired color paste film and transmitted to the printing fabric.
(2) Cause: The squeegee surface is not clean. There are many reasons why the squeegee is not clean, such as:
1 The blade is rough.
2 Scraper installation is not smooth.
3 The barrel surface is not smooth.
4 There are factors that cause chemical or physical reactions in the color paste, which damages the sharpness of the blade and makes the blade unclear.
5 Once the paste is discharged, the reducing agent in the grout will seriously destroy the color of the fabric.
(3) Preventive measures:
1 Install and adjust the scraper blade so that the mounting blade is flat, flat, flat, and flat with the flower cylinder.
2 After the chrome plating, it must be polished.
3 Reasonably choose the kind of scraper according to the nature of the color paste and the characteristics of the pattern. When using acid paste printing, corrosion resistant stainless steel blade should be used; when using vat dye paste or discharging paste, stainless steel thin blade should be used to improve blade elasticity, prevent chemical corrosion, and ensure that the squeegee is clean and not Damage to fine and shallow patterns.
4 During the discharge printing, dilute oxidizer solution (such as anti-stain salt S) may be padded before or after printing to consume a small amount of reducing agent that adheres to the color of the printing cloth, without affecting a large number of reducing agents in the pattern portion.

4. Dark and uneven printing (1) Form: In the direction of the width of the fabric, the phenomenon of dark and light print color unevenness. This is a common defect in roller printing. Checking the reverse side of the fabric can be easily detected.
(2) Cause: The pressure applied to the entire fabric web is inconsistent.
1 Scraper blade is uneven.
2 The pressure on the cylinder is not uniform.
3 Pressurize too much to bend the cone core.
4 The interlining cloth is not even.
(3) Preventive measures:
1 Install scraper blades to achieve "four levels."
2 Pressure should be even and not too large.
3 After the lining cloth is washed clean, it must be dried in the drying cylinder, and it can be used on the machine after ironing.

Source: Printing and Dyeing