Plastic film corona treatment

日期:2019/8/16 8:53:51 / 阅读: / 来源:本站

Plastic film corona treatment
(1) Corona treatment A technique of discharging a film or other material by using an electric field generated by a high-frequency high voltage in an electrode gap of a specific shape to form a certain polar group on the surface of the material to be processed. Increase the surface tension of the material being processed to enhance the printing or compounding of the car.
(2) At present, there are three main methods of corona treatment in China: 1 inductor and capacitor type; 2 crystal type; 3 thyristor type.
The inductor and capacitor type are large in size, high in noise, and the effect is poor.
The transistor type is small in size, low in noise, simple in fabrication, and easy to repair. The disadvantage is that the power is small, which is the most widely used in China.
SCR type, high power, fast processing speed, good effect, can meet the requirements of large and medium-sized equipment, high and medium speed equipment. The corona device attached to the imported BOPP film production equipment also needs such a device. However, the equipment is expensive and uneconomical, but it is required to be wider and thicker in processing or faster in processing. This type.
The corona-treated electrode forms mainly include a knife-shaped shape, a strip shape, and a needle shape. In addition to the effect of the corona treatment device itself, the electrode gap, environmental conditions, temperature and time also have a great influence on the treatment effect.
The discharge frequency is closely related to the electrode gap. When the frequency is determined, the electrode gap is too large or too small, which will cause energy loss and affect the treatment effect. If the frequency is 20 kHz, the gap is about 8 mm, and the frequency should be reduced to reduce the gap.
The ambient gas conditions during corona treatment also have a large effect on the treatment effect. When treated in air, oxygen or carbon dioxide gas, the effect is basically the same, the initial tension is increased faster, about 10s, and the tension can reach 40mN/m or more. But as time goes on, the tension is basically no longer increasing. The situation is different when treated in nitrogen, helium, argon and chlorine. The actual application is generally handled in the air. Special considerations are considered when handling in a certain gas.
The temperature and time of the corona treatment, generally below 75 ° C, the higher the temperature, the more obvious the change in surface tension. As for time, within a certain range, the longer the time, the better the effect. In actual work, if the treatment effect does not meet the requirements, the processing speed can be appropriately reduced and the processing time can be prolonged.
After the film corona treatment, the storage period should not be too long, and the most treated film generally has a certain downward trend in surface tension within 7-10 days. After that, it entered a relatively stable stage, but the tension dropped again after 1-3 months. The film should be stored in a dry, clean place.


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