Difficulties and solutions caused by temperature changes in summer printing of self-adhesive adhesive

Difficulties and solutions caused by temperature changes in summer printing of self-adhesive adhesive

1.  Problems caused by temperature changes

 

Due to high environmental humidity in summer, it can cause many troubles for adhesive printing enterprises. If not resolved in a timely manner, it may cause significant losses. Common problems with adhesive usage caused by humidity include the following:

 

 

1.1 Curling during printing

 

The majority of adhesive label printing uses UV ink, and after drying with a UV lamp, the moisture in the adhesive material will quickly evaporate. Due to the different shrinkage rates of the surface and bottom paper of the adhesive material after water loss, it is easy to cause material curling, which is particularly evident when printing film type adhesive materials.

 

 

This is because the surface material of thin film type adhesive materials is thin film, while the base paper is paper. This material does not lose any water when baked by UV lamp, while the base paper quickly shrinks due to water loss, causing the material to curl downwards. At this point, if the environmental humidity in the printing workshop is low, the base paper cannot replenish moisture from the environment in a timely manner, and the problem of material curling will not be improved, which can seriously affect production efficiency.

 

 

If the humidity in the printing workshop is controlled at a relatively appropriate level, although the material quickly loses water after being baked by UV lamps, it can be replenished with water in a timely manner in the workshop environment, so that the material will not experience severe curling and production efficiency will not be greatly affected. It can be seen that it is very necessary to reasonably control the humidity in the workshop during summer.

 

1.2 Curling after cutting into sheet

There are many self-adhesive labels that need to be cut into individual sheets, and sometimes we may find that the labels quickly curl after being cut into individual sheets, resulting in improper packaging. Logically speaking, the tension of the adhesive label material is fully released after die cutting and waste disposal, and serious curling should not occur after cutting individual sheets. So what is the reason for this?

This phenomenon is often caused by a combination of improper material selection and improper environmental humidity control. There are many types of self-adhesive material base paper, such as about 60g of grazin base paper, about 95g of coated plastic base paper, and about 120g of cardboard. In principle, it is not recommended to use self-adhesive materials with a backing paper of less than 80g for cutting labels into individual sheets. This is because the base paper is too thin and sensitive to environmental humidity. When there are significant fluctuations in humidity, this type of base paper will also elongate or shorten with changes in environmental humidity, resulting in severe curling of the adhesive material after die cutting and waste disposal.

 

 

The best solution to such problems is to choose a higher weight material as the backing paper. The higher the weight of the backing paper, the smaller the deformation caused by environmental humidity, making it easier to ensure the flatness of the label after cutting it into individual sheets.

1.3 Changes in raw material tightness

In summer, we often encounter the problem of loose and tight raw material rolls, which often occurs when the raw materials are taken out and used after being stored in the warehouse for a period of time, and some serious cases even cannot be used.

 

 

This is because there is a significant change in humidity in the summer air, and the tension of the adhesive material changes after losing water or absorbing water, resulting in loose or tight rolling of raw materials. Some materials, especially thin film adhesive materials, are also caused by the protruding core of the material during use.

 

 

Therefore, in summer, we should try to maintain a minimum inventory of adhesive materials, reduce inventory cycles, and strengthen warehouse management to achieve "first in, first out". Generally, there will be no significant changes in the arrival of materials within 7-10 days, and the maximum period should not exceed 15 days.

2 Label wrinkles and bulges

 

Summer is a high incidence period for sticker labeling failures, among which wrinkles and bulges are common problems after paper type sticker labeling. So, what is the reason for the wrinkles and bulges in labeling?

 

2.1 Water loss during processing

 

During the processing of self-adhesive materials, the self-adhesive material on the paper surface will lose some moisture after being baked by UV lamps, resulting in extremely low moisture content in the finished product label. However, when the end user uses it, they often open the packaging and directly label it. After the label is affixed, it will absorb moisture from the air and expand, forming wrinkles or bulges on the expanded area.

 

 

To avoid this problem, the best way is to add water to the adhesive material during the processing. A humidifier can be placed at the equipment winding station to add moisture to the material base paper. It is best for enterprises with conditions to install a temperature and humidity control system in the workshop to ensure the normal moisture content of the label product.

2.2 Improper storage caused

 

Usually, self-adhesive labels are packaged in plastic bags or wrapped with heat shrink film after printing, which essentially isolates them from the external environment. But when summer comes, it often rains, and after the rain, the air humidity will suddenly increase. If the label is affixed at this time, it is easy to absorb moisture from the air and expand, leading to wrinkles and bulges.

 

 

Therefore, when storing finished products with self-adhesive labels in summer, it is necessary to pay attention and try to open the packaging 24 hours before labeling use, allowing the label and the object to be placed in the same environment for 24 hours, which is conducive to balancing the humidity of both and ensuring labeling quality. Especially when the object being labeled is a corrugated cardboard box, this operation must be done to ensure the effectiveness of the labeling.