Selection of PVC film printing paste and its method
The color paste for printing all polyvinyl chloride films is not the same, and the proportion of color paste can only be determined after testing. Under special circumstances, the following requirements should be put forward for printing color paste used for polyvinyl chloride film:
① printing color paste should not contain plasticizer that will soften hard film; The printing paste used for soft films shall not contain binder that will be dissolved by plasticizer contained in the film. If the printing pigment becomes soft, it will lose its own friction strength.
② the solvent in the printing paste should not produce too strong expansion effect on the film. If the expansion effect is too large, the film will shrink and the solvent will be difficult to volatilize.
Selection of polyvinyl chloride film printing paste and its method
③ the boiling point of solvent contained in printing paste should not be too high, otherwise, the printing paste itself requires a long drying time. If there is residual solvent inside the film, it will cause adverse consequences.
④ the pigment in the printing paste should have no migration.
In addition to these special requirements, it is also required to have general light resistance and water resistance, and to have stability to grease and other foods, in some cases, good welding performance is required. Sometimes special requirements are put forward for the extensibility of the printing pigment itself. This requirement is raised when the printed film still needs to be molded. The desired printed pattern is printed on a formed object, and then it is heated above 72℃ until it shrinks and returns to the plane shape of the original film. In the lead version (That is, printing mold) The pattern left after the film shrinks is engraved on it. If the film is printed with this lead plate and then the film is formed, the original desired pattern will be correctly displayed on the forming body.
in order to ensure that the printed pattern will not be worn, a layer of cover finish paint is often applied, or a layer of cover film (Also known as sealed printing) This can be used for packaging purposes, such as chocolate packaging. When choosing the most technically reasonable and economical printing method, it is necessary to consider the size of the printing volume, the color of the printed color, the shape of the product and the quality requirements for the pattern (That is, the requirements for the fineness and accuracy of the pattern) , There are fashion needs to choose according to a number of specific circumstances.