Flat screen printing defects analysis and solutions
The printing of flat screens is ever-changing, and people have grouped them into several types. When they are finished, they are distinguished and named according to the phenomenon. In fact, there is very little recurrence of defects, and despite the same phenomenon, it is not necessarily the same reason. Here, we will analyze the most common defects and provide an analysis of the flaws for reference. This article analyzes the 31 common defects that are easily generated in the continuous flatbed printing, including the causes of the defects, the phenomenon of defects and various solutions.
1, pressure paste
The phenomenon is manifested in the unclear outline of the flower pattern, the blurring of the polychromatic contact surface, or the pressure of the sidewalk. According to the principle that there is pressure and paste, when the wet cover is wet-printed, the latter version will be pressed on the previous version, and the number of pressures on the press-fit port will be more serious.
To overcome the occurrence of this condition, first, a suitable scraper (hardness) must be selected, the grout should be squeegee-cleaned, the distance between the plate and the plate should be opened when necessary, and the middle heat be blown if necessary; the position of the correct stencil is arranged. , First print the stem after the printing block surface; deal with the draft as much as possible to open in and out, to avoid the excessive number of squeezed version; on the flower frame side of the appropriate filler treatment, reduce the contact area of the imprint.
2, paste edge
The fabric side pressure paste. Because the widths of the grey fabrics are not uniform, the first narrow width or the patch is not on the same straight line. The two ends of the flat screen are printed on the tape, then they are glued to the back of the next screen, and then printed on the next version of the cloth. , resulting in paste edge; edge suction device failure, into the cloth cloth edge is not a straight line; flat net sealing the width of the width of the large dry cloth door width.
Solution: For gray fabrics with different widths, they must be rearranged and the width of the machine printed into the fabric must be the same. The two ends of the screen are sealed from the width of the cloth and printed at the printing position, so that no extra pattern is used to print the color paste onto the conduction belt; the edge suction device is in good condition, and the distance from the conduction belt is not equidistant when the patch is applied; the doctor scrapes Width is greater than 5cm above each side of the cloth.
The outline of the flower shape is blurred and the color of the pattern penetrates into the fiber.
Causes: After the belt cleaning, the wiper does not dry, the watermark is attached to the water-conducting belt, and a watermark is generated. This results in penetration of the paste after printing. The paste has a low viscosity, a very high concentration of dye, and a large amount of printing ink. The amount of hygroscopic agent and the amount of the original paste and the poor water quality, etc., will result in the printing after the opening; after the flower plate is washed and dried, resulting in the previous version of the opening, these are to be noted.
Solution: Check the conduction band washing box wiper device is good; select a good hold water paste; check the amount of reasonable process prescription (dye saturation, different amount of fabric auxiliary agent), slurry holding time should not be too long; The version is washed and dried before use.
4, scrape into
The discolored pulp is scraped in, resulting in incorrect shades or dark colors in light-colored patterns.
The reason is: dark flowers have a large amount of pulp; the border of the flower frame is not good, and the pulp is brought into the floral version from the conduction band. Add miscoloring when adding the slurry.
Solution: According to the width of the fabric, it will stop the flower layout. When the printing paste to be net, less pulp, ground pulp. When changing color, the scraper should be cleaned to avoid the residual slurry brought into the new color pattern, the slurry can not be added wrong. Change the position of the pattern without affecting the complex color.
5, frame printing
An unusual streaks of the pattern frame shape appear on the pattern near the mouth of the pattern.
This is due to improper screens. The frame is poorly installed, the height is not the same, or the gap between the screen and the guide is too small.
Solution: Raise the height of the frame or flatten the frame, or handle the correct opening of the flower and the distance between the frame and the frame.
6, in a version of the color difference (squeegee uneven or in the fabric shows a certain interval of the depth of the shade)
Causes: The screen is inherently inadequate, the thickness of the emulsion is uneven, and the flower-shaped exposure is uneven, which affects the difference in the amount of slurry. The second is that the frame is not on the same plane or is badly installed. The third is the looseness of the scraper, the unevenness of the scraper, or the jump caused by the scraping.
Solution: For the screen defects caused by the screen must be made from the new screen, if it is film sensitive, you must also check the quality of the film. The frame is flattened, but it must be observed when printing. The installation of both screens is the same as that on the screen. Squeegee blade thickness consistent, high and low, installed in place.
7, then version
The printed color of the printing plate is embossed or overlapped or disengaged.
The reason is that the printing belt is not allowed to return to its original position; the left and right pressures of the scraper are not properly adjusted; the net frame is too high from the conduction belt; when the squeegee is found, the screen on the edge is lifted off; the open size of the flower shape is too large, and the interface is affected. Large pressure area.
Solution: According to the shape of the flower back to set the belt to run back, or check the conduction band operation is normal; Squeegee pressure is adjusted to just sizing suitable; Adjust the screen height; Screen plate can be used on the back of the large screen Set off; modify unreasonable open circuit.
8, Flower Edition
The color is uneven and chrysanthemum-like.
The reason is that when the flower plate is lifted, the color paste is pulled up, and the opposite side of the flower plate is stained with grout, which may affect the printing of the next printing plate; the viscosity of the color paste is too thick or insufficient for expanding; the amount of a certain dye is too high.
Solution: Adjust the viscosity of the flower paste or adjust the paste puffing time: After the old pulp is filtered, use it or replace it with a new one: Adjust the prescription and wash the flowers in time.
The color of the fabric exposed at the flower position or the permeability is poor, like the spotted shape of the sand skin.
Causes: After the production of flower version does not have a curing agent; Washed in clean, or spend a long time spent on the flower version, the pulp section to make the mesh smaller lead to plug; Scraper improper use or pressure is too small, not enough sizing; Color paste Viscosity is too thick to make it difficult to squeegee; greasy stains, waxiness, etc. are found on the grey cloth; the front quilt is not dried and is sucked up by the reverse side of the rear stencil.
Solution: check the version of the hole after the production of the flower pattern is good; after each printing, the screen should be cleaned; select the doctor blade and use the appropriate force; for the gray cloth to be printed, the capillary effect must be tested; if necessary, the fabric can be renewed; each time The paste should be tested for paste viscosity: Select the mesh number corresponding to the pattern.
10, thick and thin stem
Fine stems vary in thickness.
Causes: The thickness of the screen is too small; the left and right magnetic sizes of the magnetic table are different, resulting in different printing pressures; the screen is not flat; the pressure of the doctor blade is inconsistent, the knife edge is not uniform, the thickness of the doctor blade is not uniform; the squeegee is not net. .
Solution: Carefully check whether the fine stem of each returning position is the same; check the magnetic force of the magnetic station; lay flat when printing installation screen; select a good scraper and adjust the pressure of the scraper; the knife edge should be the same when changing the scraper; According to the thickness of the fabric, adjust the height of the mesh drum.
11, flower shape skew
The pattern is inclined or curved for the warp and weft yarns of the fabric.