How to choose the conditions of thermal sublimation transfer process?

The important parameters of thermal transfer printing process are temperature, time and pressure during transfer, among which temperature and time are basic conditions.

1. Transfer temperature: Temperature is an important parameter of thermal transfer. The higher the temperature, the higher the transfer rate. Because temperature has a direct impact on dye sublimation, the transfer temperature should be determined above the dye sublimation temperature, that is, the temperature of dye sublimation is the lowest temperature during transfer printing processing. When the temperature reaches this temperature, the dye begins to sublimate. But it is not the highest temperature for dye sublimation. The highest temperature should be determined by whether the fiber is damaged. Therefore, the selection of the best temperature should be comprehensively considered based on factors such as fiber and dye, and is generally selected at around 200 degrees Celsius.

2. Transfer time: The thermal transfer time is usually controlled at around 30 seconds. The transfer time here includes two parts. One is the sublimation time of the dye, and the other is the time for the dye to condense on the surface. Disperse dyes of different colors have different diffusion coefficients. Properly extending the heating time will increase the brightness of the dye color. However, excessively extending the transfer time has no practical significance. Instead, it delays production efficiency and causes a decline in print quality. Because the temperature is too high and the time is too long, the fiber will feel rough and the color will turn yellow. On the contrary, if the temperature is too low and the time is too short, the transfer effect will not be ideal.

3. Transfer pressure: Transfer pressure is an important factor to ensure the quality of transfer. The greater the pressure, the better the transfer effect. It mainly reduces the distance between the fabric and the transfer paper, and the less the vaporized disperse dyes collide and escape in the air, the higher the transfer printing coloring. However, the pressure cannot be increased infinitely, because excessive pressure will cause obvious indentations between the compressed area and the non-compressed area of ​​the fabric. In order to ensure the appearance quality of the printed product, a decompression hot stamping machine can be used, that is, the so-called vacuum transfer printing with air extraction. Decompression transfer printing can also make some disperse dyes that have not sublimated downward be used, and at the same time it can also increase the brightness of the printed color and increase the transfer printing speed.

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