What are the common problems of self-adhesive paper in the rainy season?

Characteristics of self-adhesive paper: Self-adhesive paper is a multi-layer composite structural material composed of backing paper, adhesive (glue), and facing material. Due to its inherent characteristics, many factors can affect the processing or usage effects during processing and usage. As the rainy season of summer arrives, the air humidity continues to increase. Different paper and film materials exhibit different behaviors under the influence of external humidity, leading to various problems during the use of self-adhesive paper.

Case Study 1: Wine Label Application
Issue: The customer used copperplate-paper self-adhesive labels with hot stamping and varnishing processes in addition to printing. Initially, there were no issues with the application, but after 24 hours, the labels on the wine bottles began to wrinkle. Over time, the wrinkling on the bottle labels became increasingly severe.
Analysis: As it was the rainy season, the humidity in the customer's workshop was relatively high. The self-adhesive labels were sealed in plastic bags before use, resulting in a significant difference in moisture content between the labels and the workshop environment. After application, the labels quickly absorbed moisture and expanded, leading to wrinkling.

Case Study 2: Wrinkling of Labels on Corrugated Paper Boxes
Issue: Wrinkling occurred on the labels of corrugated paper boxes after labeling. The wrinkling became apparent 24 hours after the boxes were labeled.
Analysis: The labels were packaged in plastic bags and stored in the warehouse. However, the corrugated paper boxes provided by the printing factory were stored in the same warehouse without any outer packaging. The warehouse did not have humidity control. Firstly, the boxes in the warehouse were more susceptible to moisture than the labels. Secondly, the boxes themselves had a relatively high moisture content, resulting in the "dry" labels being applied to the "wet" corrugated boxes. After some time, the labels exhibited wrinkling as the wet boxes lost moisture and shrunk, causing wrinkling.

Case Study 3: Curling of Self-Adhesive Materials During Printing and Die-Cutting
Issue: Curling of self-adhesive materials during printing or die-cutting, especially with film-based self-adhesive materials, is a common issue during the rainy season. This is because the facing material of film-based self-adhesive materials is largely unaffected by external moisture, but their backing paper is often highly influenced by ambient moisture. Some customers have reported that a film-based self-adhesive material could not be used normally due to severe curling during the printing process.
Analysis: During the rainy season, the humidity in the customer's production workshop is relatively high. During processing, the backing paper of the self-adhesive material rapidly absorbs moisture and expands, causing the material to curl severely towards the facing material. Customers use tension-free paper collectors, making it difficult to collect the curled material normally.

Precautions for Using Self-Adhesive Paper During the Rainy Season:

1. Open the outer packaging of the labels before application and allow them to equilibrate with the humidity of the labeling environment for a period of time. This will prevent the labels from absorbing excessive moisture and expanding, which can lead to wrinkling.

2. Modify the label processing techniques. Consider using lamination instead of varnishing. This effectively blocks the labels from absorbing external moisture, thereby reducing the likelihood of wrinkling.

3. During printing and processing, increase the moisture content of the labels by using a secondary humidification method. For example, a humidifier can be used to add moisture to the backing paper of the labels during processing and die-cutting. This ensures that the labels are not too dry, reducing the impact of changes in external humidity on the labels.