Three common printing plate in Carton industry:
1, rubber plate. The rubber plate was the first printing plate to be engraved by hand and has now evolved to be engraved by laser. This plate thickness is 7mm, the main material is rubber, generally used for simple text and line patterns, printing requirements are not high. This version because the price is very cheap, the current application is more widespread.
2, flexible resin version. It consists of three pieces: a polyester protective layer on top, a photosensitive polymer in the middle, and a polyester on the bottom. This version is made by Seihan machine, version of the thickness is 3.94 mm, generally used for fine text and 90 lines below the level of graphics and text. This version is the carton industry's most widely used printing version, so this article focuses on flexible resin version.
3. Thin version of high-line. With emergence of this trend, the current flexo printing is to replace offset printing, the high graphic and thin printing plate is more and more used. High Net line thin version is mainly used for more than 5 colors, 90 net line above fine graphics and text. It is 1.7 mm CTP Direct making plate. For CTP Direct making plate and flexo plate, there are two differences: one is the thickness, the thinner version, The smaller graphics deformation, the higher the precision; two is the plate making method, so thin version, with the traditional plate making method, it can not be satisfied, it needs to use laser irradiation, through the computer to control the laser head directly, so the precision is very high. Second, the solid photosensitive resin flexography process, the composition of the solid photosensitive flexography, as shown in Figure
Use hand to tear the plate surface of the protective film, the middle layer of photosensitive is resin, the following is the substrate.
Solid resin plate making process consists of 8 steps: negative image preparation, cutting plate, back exposure, main exposure, washing, drying, post-processing, post-exposure. First of all, we have to prepare a negative picture, that is, black and white film; the film on the plate, according to the standard cutting plate; Back exposure is mainly to harden the back, improve the support of the version; Then enter the main exposure, the surface of the graphic exposure and hardening; After the completion of the main exposure to wash plate washing process is to wash off the unnecessary part, that is, to wash off the unexposed part, leaving the hardened text has been exposed; After washing the plate into the drying process, the washing liquid evaporation, so that the version of the original form, because the plate in the washing liquid soaking will occur slight deformation, so to dry; After drying, it is necessary to carry out post-treatment, mainly to stick, because the liquid medicine and printing plate after washing, there will be subtle chemical changes, produce viscosity, then the appropriate ultraviolet irradiation, so that the surface again hardening; After removing the viscosity, the post exposure is carried out to uniformly harden the surface of the printing plate comprehensively, strengthen the surface hardness of the printing plate, and improve the service life of the printing plate. This is the whole process of solid resin plate making.
1) Check film: mainly check the clarity and blackness of film. Whether the direction of the image is correct, whether the density is above 35, and whether the density of the blank is below 0.06. Density check is very important, through the density check, to ensure the light transmission, so as to ensure the quality of the subsequent plate.
2) Cutting plate: cutting plate should be based on the size of the negative picture, plate edge reserved 12mm, to facilitate the sealing process behind; At the same time, also pay attention to the printing plate face up to cut, when the plate must be flat, can not have creases, because once there is a crease, the printing plate is uneven, behind the plate will appear problems.
