Detailed explanation of thermal transfer base film

Detailed explanation of thermal transfer base film

Common thermal transfer base films include films made of materials such as PET and OPP, among which PET film is the most common type of thermal transfer base film. Next, we will focus on some basic theories of PET film as a thermal transfer base film.

1. Introduction to base film

Photo of thermal transfer base film

PET film is also known as high-temperature resistant polyester film. It has excellent physical properties, chemical properties, dimensional stability, transparency, and recyclability. When PET film is used to make thermal transfer base film, it uses the characteristics of high tensile strength, good thermal stability, low thermal shrinkage, smooth surface, and good peelability of PET film to achieve the production of thermal transfer film and ensure its stable quality.

The thermal transfer base film is a medium material of the thermal transfer process, which plays a connecting role in the entire thermal transfer process. The post-process of thermal transfer is to heat and pressurize the thermal transfer base film once by the thermal transfer machine, and transfer the decorative pattern on the thermal transfer base film to the surface of the substrate to form a high-quality finishing pattern.

2. Thermal transfer base film usage parameters

The thermal transfer base film has its own unique properties. In order to obtain the ideal hot stamping effect, the optimal temperature, pressure and speed must be strictly controlled to match the process characteristics of the thermal transfer base film. It has three strict process parameter indicators:

1. Determination of temperature:

When the temperature is too low, the pattern will not be firmly hot stamped; when the temperature is too high, the ink layer of the pattern will oxidize on the surface, causing the pattern to lose its proper gloss, the color to darken, and in severe cases, bubbles will form.

To determine the optimal hot stamping temperature, the following factors should be considered: pressure, speed, area, room temperature and other factors.

The hot stamping temperature generally ranges from 140℃ to 260℃ depending on the material of the substrate. Once the optimal temperature is determined, the temperature of the hot stamping machine should be kept constant, and the temperature difference should be controlled within ±2℃ as much as possible.

2. Determination of pressure:

The hot stamping pressure is generally 4-6 kg/cm2.

If the pressure is too low, the thermal transfer film cannot form a close contact with the substrate, reducing the adhesion of the pattern; if the pressure is too high, the substrate will be deformed under pressure, affecting the overall printing effect of the substrate.

If the hot stamping surface is not flat enough, you should also pay attention to the uniformity of each pressure point, and the pressure angle between the silicone roller and the substrate should be higher, otherwise, it is very easy to have uneven adhesion of the substrate pattern.

3. Determination of speed:

This is determined according to the hot stamping area of the substrate, and the power of the heating system of the thermal transfer machine should be considered.

The order of temperature, pressure and speed is: speed first, pressure second, and temperature last.

3. Precautions for base film storage

Thermal transfer base film products should be stored as follows:

A. Handle with care, and only store vertically and not horizontally;

B. At the same time, it cannot be stored near heat sources to avoid melting of the adhesive on the back of the thermal transfer film due to high temperature, so it must be kept away from heat sources, and it is generally better to store it at 25℃;

C. Prevent moisture. Once it is damp, it should be dried in time, otherwise it will produce gas during use, which will affect its use effect.