Dyestuff through the role of the medium of gel, firmly attached to the fabric, gum paste printing process to overcome the limitations of water paste printing. But gum paste printing process often appear back sticky phenomenon, so what is the cause of it?
1, printing glue paste printing good sticky hands problem. Printing paste printing after drying sticky hands phenomenon, as the temperature rises and more serious.
Reason: the main raw material of printing paste is acrylic resin, the characteristics of the resin, the choice of harder resin, the problem of sticky hands can be solved, but the adhesion decreases very seriously, if you increase the adhesion, you must choose a relatively soft resin, but soft resin is easy to back stick.
Solution: the use of printing paste anti-adhesive agent, added to the printing paste mixed evenly, after printing, printing paste anti-adhesive can form a film on the surface, not only does not affect the adhesion of printing paste, but also solve the problem of sticky hands.
2, flat screen fabric printing in the solution to the phenomenon of stuffing network. Causes: the base sheet density is not enough; flat screen plate making improper operation process; printing paste quality problems.
At present, the base sheet is produced by computer. The higher the density of the pattern to black, the better the shading effect. If the blackness is not enough, the poorer the shading effect, ultraviolet light is easy to pass through, it will cause the plug; the gray haze of the base sheet should be low, such as high gray haze, blocking the ultraviolet light through, need to lengthen the exposure time to complete, so easy to cause excessive exposure time and plug.
Printing, the use of slurry containing impurities or undissolved particles clogged in the mesh, so that the printing color paste can not be scraped out of the mesh, so the slurry should be filtered to impurities before use. Make the coating adhesive to choose a good quality adhesive and good compatibility of the thickener, scraping the film should not be too fast when printing.
3, the edge of the pattern from clear to blurred generation process just started printing because of the good fluidity of the paste, so the ink scraper does not need a lot of force to cut the paste clean. With the continuous evaporation of water in the rubber pulp, pulp gradually thicken, viscosity becomes larger, must increase the size of the ink scraper knife to cut clean excess pulp. As the strength increases, so that the screen elastic deformation of the pattern displacement, with the disappearance of the force of the ink scraper, the screen rebound after the printing surface of the screen pattern edge will be counter-sticky to the paste, in the second printing, the paste will be moved to the edge of the pattern, resulting in blurred pattern edge phenomenon.
(1) use a screen with little elasticity, such as polyester silk screen; (2) improve the tension of the screen; (3) reduce the rebound force of the screen; (4) adjust the viscosity of the paste at any time.
4, the pattern of sharp corners into rounded corners, small dot loss causes. Due to the gradual thickening of the paste in the printing process, so that its mobility becomes smaller, when passing through the mesh must increase the pressure of the squeegee to pass through the mesh, but in the edge of the screen pattern due to the photopolymer support pad role, so that the squeegee can not always extrude the paste out of the mesh, so that the paste particles stay in the mesh to form a film, resulting in photopolymer edge of the mesh blockage.
(1) the use of low mesh, monofilament, thin screen; (2) photopolymer can not be too thick; (3) paste to maintain a certain degree of fluidity at all times.
5, gel paste in the printing process to produce the cause of crusting phenomenon. Any printing material has a common characteristic, namely: the thinner the ink layer the faster it dries, the same applies to gum paste. Because the screen is larger than the pattern, the screen has enough space to stack the paste, the ink scraper is not possible to collect the paste clean at each printing, especially in the pattern above the often produce a thin ink layer, these ink layers will be in a short period of time into a semi-dry film, these films are brought into the bias hole by the ink scraper to block the mesh, forming a local blocking phenomenon.
In the screen pattern area and the screen frame between the wooden strip to do isolation, the pulp control in a certain range, the squeegee can each time the screen pattern side of the pulp to collect clean, also means that the pulp in this range is not possible to produce a thin ink layer, so you can put an end to the crust phenomenon.
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