Metal thermal transfer: preparatory steps before thermal transfer film production
Before the thermal transfer film is printed, it must first be analyzed and studied carefully according to the requirements, and then according to the printing process steps.
1. Preparation of substrate film
There are many kinds of carriers for thermal transfer film, and PET is widely used. It has the characteristics of good dimensional stability, uniform tension, good heat resistance, and good release properties. Especially it has obvious advantages in the reproduction of color gradation originals. The specifications of the film, such as width, thickness, and brand, are selected according to the manufacturer's requirements. At the same time, check the flatness of the film and whether the tube material has "protruding ribs", "flounces" and other conditions that do not meet the quality requirements.
2. Preparation of release agent
Low-viscosity transparent resin with release properties, film-forming properties and adhesive properties. Because the solvent in the release agent evaporates faster, it is necessary to control the viscosity during the coating process, that is, control the solid content of the release agent , The solid content is generally controlled at about 23%, if the solid content is less than 19%, the thermal transfer film transfer effect after coating the release agent is not ideal. At the same time, pay attention to the transparency of the release agent, otherwise it will affect the effect of the printed layer.
3. Preparation of ink
Thermal transfer ink is a gravure ink. The drying of the ink mainly depends on the volatilization of the solvent. After the substrate film is determined, the appropriate ink should be selected according to the purpose of the printed matter and the nature of the printing material or according to the requirements of the construction order. Check the fineness, viscosity, hue, tinting strength and other indicators of the ink to see if all meet the printing quality requirements for the ink.
4. Preparation of adhesive
The adhesive for heat transfer is a hot melt adhesive, which is a colorless, transparent or light yellow viscous liquid. After coating and drying to form a film, the film is transparent. It has excellent composite firmness on the surface of the coated release agent and ink. Degree and superior flexibility, abrasion resistance, strong resistance to media such as water, acid and alkali, and good weather resistance. Matters needing attention in the coating process When the material is fully prepared, it can be printed on the printing machine. Generally, the release layer, printing layer and adhesive layer are all coated and printed on the same gravure printing machine.