Precautions for corona treatment before PET film printing

Date: Oct 16 2024 From: Star Color

PET film has a wide range of applications in packaging, electronics, printing, and other fields due to its excellent physical properties and chemical stability. Due to the low surface tension of PET film and its weak affinity for water-based ink, corona treatment is required before printing to increase its surface tension and enhance the ink adhesion ability.

The main purpose of corona treatment is to generate discharge between the metal electrode and the corona treatment roller through a high-frequency and high-voltage power supply, ionize the air, and form ozone and low-temperature plasma. These plasmas impact and activate the surface of PET film, increasing its surface roughness and surface tension, making it easier to accept ink adhesion.

Precautions for corona treatment

1. Selection and operation of corona treatment machine
O Normal operation of corona treatment machine: Ensure that the corona treatment machine operates normally, the corona force is accurate, and there are sufficient backup corona treatment machines to cope with emergencies.

2. Control of corona treatment intensity
Moderate treatment: The higher the corona treatment intensity, the better. Excessive processing intensity may lead to excessive activation of the film surface, which in turn affects the adhesion of ink. Therefore, the appropriate corona treatment strength should be selected based on the material of the film and printing requirements.

3. Cleaning and transportation of thin films
Keep the film clean: After corona treatment, static electricity will be generated on the surface of the film, which can easily adsorb dust and impurities. Therefore, during handling and transportation, it is necessary to maintain the cleanliness of the film to avoid contamination.
Timely use: The film after corona treatment should be used in a timely manner to avoid prolonged storage that may cause a decrease in surface tension. It is generally recommended that the time from blow molding to printing should not exceed 15 days.

4. Safety issues during corona treatment process
Protective measures: During the corona treatment process, harmful substances such as ozone and nitric oxide are generated. Operators should wear protective masks and gloves to avoid prolonged exposure to these substances.

5. Monitoring of Printing Quality
Corona effect detection: During the blowing, cutting, and printing processes, continuous corona effect detection should be carried out on the film to ensure that the surface tension meets the printing requirements. If the printed text pattern reaches 36 dynes, and the printed large color blocks reach 38 dynes or more.

Precautions for corona treatment before PET film printing

The influence of corona treatment on the properties of PET film

Corona treatment not only affects the surface tension of PET film, but also has an impact on its other physical properties. Corona treatment will reduce the shrinkage rate of the film and affect the heat sealing strength of the heat sealed film. In production, it is necessary to choose a suitable corona treatment process based on the purpose and performance requirements of the film.

The corona treatment before PET film printing is an important step to improve its surface tension and enhance ink adhesion ability. During the corona treatment process, attention should be paid to the selection and operation of the corona treatment machine, control of the corona treatment intensity, cleaning and transportation of the film, safety issues, and monitoring of printing quality.