What's the heat transfer film?

 

Heat transfer film refers to a printing film with a special function of adhesive, which is separated from the carrier film and the release layer under the action of heat and pressure, and is firmly transferred to the surface of the substrate. Thermal transfer films usually consist of 3 to 5 layers. The three-layer heat transfer film consists of a base layer, a printing layer and an adhesive layer.

 

The four-layer heat transfer film consists of a base layer, a release layer, a printing layer and an adhesive layer. The five-layer heat transfer film is composed of a base layer, forming a release layer, a printing layer, an adhesive layer and a hot melt adhesive powder layer. There are many carriers for heat transfer films, the most widely used is PET, which has the characteristics of good dimensional stability, uniform tension, good heat resistance and good mold release.

 

Especially in the reproduction of tonal manuscripts has a clear advantage. Film specifications such as width, thickness and grade are selected according to the manufacturer's requirements. At the same time, the flatness of the film must be checked, and whether the material of the cylinder has "bumps" and "side edges" that do not meet the quality requirements.

 

The release agent is a low-viscosity transparent resin with mold release, film-forming and adhesive properties. Since the solvent volatilizes faster in the release agent, care must be taken to control the viscosity during the coating process, that is, to control the viscosity. The solids content of the release agent is usually controlled at about 23%. If the solid content is less than 19%, the transfer effect of the heat transfer film after applying the release agent is unsatisfactory.

 

At the same time, pay attention to the transparency of the release agent, otherwise it will affect the effect of the printed layer. heat transfer inks are gravure printing inks. The drying of the ink mainly depends on the volatilization of the solvent. After the substrate film is determined, the appropriate ink is selected according to the purpose of the print and the properties of the printed material or according to the requirements of the building board.

 

Check ink fineness, viscosity, hue, tinting strength and other indicators to see if they all meet the ink's print quality requirements. Thermal transfer adhesives are hot melt adhesives, which are colorless, transparent or light yellow viscous liquids. After coating and drying to form a film, the film is transparent and has excellent compounding degree and excellent flexibility, abrasion resistance, water and acid, alkali resistance on the surface coated with release agent and ink strong, and good weather resistance.