Example Discussion of Die Cutting Process

Self-adhesive label is a multilayer composite material composed of backing paper, adhesive, and face material. Due to its own characteristics, there are many factors that can affect the processing or usage effect during processing and usage. With the arrival of the rainy season, the air humidity keeps increasing.

Therefore, various problems are prone to occur during the usage of self-adhesive labels in the rainy season. Below, we will share with you the precautions for using self-adhesive labels in the rainy season and problem-solving solutions through two case studies.

Wrinkles on self-adhesive labels when applied to wine bottles

I once encountered a case where a customer used self-adhesive labels to stick on wine bottles. Initially, there were no issues, but after 24 hours, wrinkles appeared on the labels on the bottles. And as time went on, the wrinkles on the labels became more and more severe. The self-adhesive labels used by the customer were made of copperplate paper and underwent processes such as printing, hot stamping, and varnishing. The customer found this situation quite strange because they had used this type of label before and had not experienced such issues.

Through analysis, the true cause of the label wrinkles was identified. At that time, it was the rainy season, and the humidity in the customer's workshop was high. The self-adhesive labels were sealed in plastic bags before use. As a result, there was a significant difference in moisture content between the labels themselves and the workshop environment. The labels quickly absorbed moisture and expanded after being applied, resulting in wrinkles.

To solve this type of problem, there are several methods:

1. Open the packaging of the labels before application and let them sit in the application environment for some time. This allows the labels to balance their moisture content with the humidity of the application environment, preventing excessive moisture absorption and resulting in expansion and wrinkles after application.

2. Modify the label processing method by using lamination instead of varnishing. This can effectively prevent the labels from absorbing external moisture, thereby reducing the probability of wrinkles.

3. During the printing process, adopt a secondary humidity adjustment method to increase the moisture content of the labels. For example, a humidifier can be used to humidify the backing paper of the labels during the processing and die-cutting process, ensuring that the labels are not too dry and minimizing the impact of changes in external humidity.

Curling of self-adhesive materials during printing and die-cutting

In the rainy season, cases where self-adhesive materials curl during printing or die-cutting, affecting the production process, are also quite common. This problem is particularly prominent in the usage of thin film self-adhesive materials. This is because the face material of thin film self-adhesive materials is almost unaffected by external moisture, but the backing paper is often greatly affected by external moisture. I have seen cases where a customer complained that a thin film self-adhesive material couldn't be used properly due to severe material curling during the printing process.

Upon investigation, it was found that it was also the rainy season at that time, and the humidity in the customer's production workshop was high. During the processing, the backing paper of the self-adhesive material quickly absorbed moisture and expanded, resulting in severe curling towards the surface layer. Since the customer used a tension-free paper roll for paper collection, the material curling made it almost impossible to collect the paper properly.

To solve this type of situation, the following methods can be adopted:

1. Strengthen the control of workshop temperature and humidity. We all know that the optimal temperature for printing is between 20-25 degrees Celsius, with a relative humidity between 50-60%. Therefore, in order to produce good products, it is necessary for enterprises to control the workshop temperature and humidity effectively, so as to fundamentally solve this problem.

2. For enterprises that cannot control temperature and humidity conditions, the issue can be resolved by locally adjusting humidity. For example, heating pipes or heat fans can be installed near the equipment's winding position to lower the humidity locally and solve the problem.

If the workshop humidity is too high, consider opening the material packaging and placing it in the workshop for 24 hours before printing and using, allowing the material to reach moisture balance with the workshop environment. This can to some extent improve the curling problem of self-adhesive materials caused by excessive humidity.