The printing color of the modern printing industry has developed from monochromatic to six-color and eight-color, and the efficiency has evolved from multi-process to one-time forming with continuous machine, integrating printing, cutting, bumping, bronzing, and laser. In the process of electromechanical integration, a series of new problems will inevitably appear in production. The trademark bending is a quality problem that is often encountered in the one-shot molding production of even machines. Trademark bending not only affects the appearance of the trademark, but also directly damages the user's suitability for computer use, causing users to be dissatisfied and stop using such trademarks. How to effectively solve and control the trademark bending in production is of great significance to improve product quality and meet user needs.
Why does the film bend during printing?
It is known from the test that under certain pressure and temperature conditions, the greater the pulling force, the higher the temperature and the greater the deformation of the film.
In the one-time molding production process of the gravure printing multi-color continuous machine, the film is subjected to 20daN ～ 35daN tension, 25daN ～ 40daN pressure, and drying temperature of 60 ℃ ～ 100 ℃. After multiple printing drying, stretching, and recovery, it deforms to varying degrees And, in the printing, due to the application of ink, it will cause different stretching, deformation, and recovery of the film surface on the transverse width of the local and the positive and external sides, so the trademark bending phenomenon occurs in the finished product, especially the uniformity of the tension is poor The quality of the film will be severely bent.
For the bending phenomenon that occurs in trademark production, the following measures can be taken:
(1) Thin film control
In order to reduce the bending of the trademark, in the selection of printing film brands, it is necessary to reasonably select famous products with high technical content, which can ensure the reliability of PP resin, reliable control of film thickness uniformity change, and uniform slitting and rewinding tension. Ensure that the film surface state and tension are balanced, which is conducive to printing and avoid bending.
(2) Control of ink and solvent
In the printing process, due to the application of ink on one side of the film, the ink, resin, trademark pattern, and solvent volatilize, which have different effects on the bending of the trademark. On the premise of ensuring that the pattern and color meet the needs of users, compare the origin of the ink, the thickness of the application, and the choice of solvent. The ink must be selected for the resin with strong solubility, good performance, and not easy to sizing; the thickness is in the plate making according to the product requirements The depth of the mesh is generally not more than 35μm; the use of the solvent must maintain the balance of the mixed solvent, that is, it cannot be too volatilized, and participate in a certain temperature (generally not more than 80 ℃), so that the product does not stick.
(3) Coordinated relationship between vehicle speed and pulling force
Under certain conditions of tension in the printing process, the higher the printing speed, the greater the degree of trademark bending; conversely, the printing speed is constant, the greater the tension, the greater the bending of the trademark. In order to give full play to the efficiency of the equipment in production, it is impossible to reduce the speed of the vehicle to solve the problem of trademark bending. Therefore, it is necessary to reasonably choose the tension parameters to solve the quality problem. For example, in operation, the vehicle speed is 130m / min, the front tension is 20daN, and the rear tension is 35daN, which is an ideal parameter. As for the selection of actual parameters, it can be adjusted according to the printing effect.
(4) Influence of drying temperature and air volume
The higher the temperature in the drying oven, there are certain benefits to the printing process, but the temperature is too high, the phenomenon of trademark bending will occur, therefore, for gradation printing, the temperature is generally stabilized at 55 ℃ ~ 90 ℃. The inlet air pressure and exhaust air pressure of the oven must be balanced. If the amount of exhaust air is too large, the film shrinks strongly, and the trademark is severely bent.
(5) The influence of ink, printing pattern and solvent on the bending of the trademark (listed in the table below)
Bending degree Varnish Printing area Solvent
Big domestic full version evaporates quickly
Medium Domestic famous brand strip Volatile
Small import irregular evaporation slow
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