The coating of corona roller is a very important component in modern packaging, printing and plastic industry, especially when corona treatment is performed on the surface of plastic film, paper and other materials, corona roller plays a vital role. Corona treatment is to change the surface properties of materials through high voltage discharge to improve their adhesion and wettability, and the coating of corona roller is one of the core components in this process, which directly affects the effect of corona treatment.

The coating of corona roller is made of special materials, which are subjected to the influence of corona discharge, temperature, chemical substances and other complex conditions during operation. Therefore, the performance of the coating of corona roller will gradually decline over time and eventually need to be replaced. So, how to judge when the coating of corona roller needs to be replaced? This is not only related to production efficiency, but also affects the quality of products and the cost control of enterprises.

This article will discuss in detail the criteria for judging when the coating of corona roller needs to be replaced, analyze the factors affecting the life of the coating, and put forward corresponding inspection methods and maintenance suggestions.

What is the role of the coating of corona roller?

Before going into the in-depth discussion of when the coating of corona roller needs to be replaced, it is necessary to understand the role of the coating of corona roller and its working principle. The coating of the corona roller is usually made of high temperature resistant and electrical corrosion resistant materials, in order to ensure that the coating can withstand the impact of current, the heat of surface discharge and the friction of the material surface in constant contact during the corona discharge process.

The role of the corona roller is mainly reflected in the following aspects:

● Improve the surface energy of the material: The core goal of corona treatment is to improve the surface energy of the material, making it easier to accept subsequent treatments such as coatings, inks, adhesives, etc. The corona roller uses the electric field to change the molecular structure of the surface of the material passing through, thereby improving the adhesion.

● Optimize the adhesion of the surface coating: For materials such as plastic films and metal foils, corona treatment can enhance the adhesion of materials such as inks and glues, and prevent shedding or unevenness during subsequent processing.

● Prevent material aging: Corona treatment can prevent the surface of the material from aging or fading due to long-term exposure to the external environment to a certain extent, and improve its durability and aesthetics.

● Improve production efficiency: Through corona treatment, the surface adhesion is enhanced, which can reduce failures in processes such as coating and printing, thereby improving production efficiency.

Degradation process of corona roller coating

The coating of corona roller will gradually degrade during long-term use, affecting the effect of corona treatment. The degradation of coating is a gradual process, which is affected by many factors. Common degradation phenomena include coating wear, cracks, electrical corrosion, temperature aging, etc.

● Coating wear: During the corona treatment process, the coating is constantly in contact with the surface of the material to be treated, especially under high temperature and high voltage conditions, the surface of the coating is easily rubbed, resulting in wear and peeling of the coating.

● Cracks and breakage: The long-term effect of high voltage and temperature can easily lead to cracks or breakage of the coating, especially when the voltage resistance of the coating material is insufficient, local damage may occur. These cracks not only affect the integrity of the coating, but also may cause uneven corona effect.

● Electrical corrosion: During the corona treatment process, the coating is subjected to high voltage, especially if the coating material of the corona roller does not have strong electrical corrosion resistance, electrical corrosion is prone to occur, resulting in degradation of the coating material.

● Thermal aging: During the corona treatment process, the coating is subjected to high temperatures, especially in high temperature environments, the chemical structure of the coating material may change, resulting in a decrease in its performance.

● Chemical aging: Over time, the coating material may react with oxygen, moisture and other chemicals in the air, undergo chemical changes, resulting in a decrease in coating performance, affecting its wear resistance, adhesion and other indicators.

How to judge whether the corona roller coating needs to be replaced?

When the coating of the corona roller degrades, it will directly affect the effect of the corona treatment and ultimately lead to a decrease in product quality. Therefore, it is crucial to judge when the corona roller coating needs to be replaced. The following are some common judgment criteria:

1. Surface wear or damage

The surface wear of the corona roller coating is the most direct indicator. By regularly checking the smoothness and integrity of the corona roller surface, it can be determined whether the coating is worn. If there is obvious wear, scratches or peeling on the coating surface, it means that the protective function of the coating has failed and must be replaced as soon as possible.

2. Reduction of corona effect

The effect of corona treatment is directly affected by the state of the corona roller coating. If the corona effect is significantly reduced (such as decreased adhesion of materials, poor adhesion of printing inks, etc.), it often means that the function of the coating has declined. In this case, replacing the coating is a necessary step to restore the treatment effect.

3. Cracks or partial damage to the coating

If the coating of the corona roller is cracked or partially damaged, it means that the coating has lost its integrity and can no longer be effectively corona treated. Cracks are usually caused by excessive voltage, excessive temperature or long-term friction. At this time, even if the corona roller continues to be used, it may cause uneven treatment effects on the surface of the material and even cause equipment failure.

4. Signs of electrical corrosion

Electrical corrosion is one of the common causes of degradation of the corona roller coating. Electrical corrosion of the coating is usually manifested as spots, discoloration or damage on the coating surface. If obvious corrosion marks are found on the coating surface, it means that the electrical corrosion performance of the coating has declined and it is necessary to consider replacing the coating.

5. Abnormalities when the temperature is too high

If the coating of a corona roller working at high temperature softens, deforms or peels, it means that the temperature resistance of the coating has declined. Continuing to use it at this time will affect the stability of the production process and product quality. Through temperature monitoring, combined with the heat resistance of the coating, it can be determined whether the coating needs to be replaced.

6. Abnormal current and voltage

The current and voltage of the corona roller are the key factors that determine the corona effect. If the current and voltage are too large or too small, the corona discharge may be unstable due to the degradation of the coating. At this time, the condition of the corona roller coating should be checked, and whether to replace the coating should be decided according to the situation.

How to extend the service life of the corona roller coating?

In order to extend the service life of the corona roller coating, reduce the replacement frequency, and maintain the effect of corona treatment, enterprises should take certain preventive and maintenance measures during use.

● Regularly check the integrity of the coating: Through regular inspection and maintenance, problems such as coating wear and cracks can be discovered in time to avoid further deterioration of the problem. Professional detection tools such as ultrasonic detectors and infrared thermometers can be used for comprehensive monitoring during inspection.

● Control the parameters of corona treatment: Reasonably control the voltage, current, processing speed and other parameters of corona treatment to avoid damage to the coating caused by excessive voltage and excessive processing time.

● Optimize the operating environment: Ensure that the working environment of the corona roller is stable and avoid excessive temperature and humidity that may affect the coating. In addition, regularly cleaning the corona roller to prevent the accumulation of dust and pollutants can also help extend the service life of the coating.

● Use high-quality coating materials: Selecting coating materials with higher corrosion resistance and high temperature resistance can effectively extend the service life of the coating. High-quality coating materials can better withstand the effects of high voltage current, temperature changes and other factors.

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