Winter is coming, have you done the right thing in storing self-adhesive labels! Let's take a look at the classic case analysis!

Self-adhesive labels are very sensitive to temperature changes during processing and use. Especially with the arrival of winter, some label printing companies are prone to some problems when processing and using self-adhesive labels, such as wrinkling and bubbling. If these problems are not solved in time, they will greatly affect the production efficiency of label printing companies and the use effect of end users. In serious cases, they may even cause large economic losses. In this article, the author shares several cases with you. Let's take a look at the key points that should be paid attention to during the storage and labeling of self-adhesive labels. I hope it will be helpful to everyone.

Case 1: Frostbite and hardening of self-adhesive labels

When a printing factory processed self-adhesive labels in an environment of 0℃~3℃, the adhesive of the self-adhesive labels had frostbite and hardening problems, which greatly damaged the processing process of the printing factory and caused great trouble.

After observation, it was found that the self-adhesive materials used by the printing factory had serious stratification in the paper feeding part of the machine. The bonding force between the surface material and the base paper after stratification dropped sharply, or even lost, so that the labels processed later could not adhere to the base paper normally, causing the label processing process to be blocked. In addition, it was also noted that the processed labels were easily taken away by the waste edges during die-cutting and waste discharge, and when the labels were transported on the stripping or label sorting machine, they would separate from the base paper when passing through some small rollers or large corners, causing the "flying label" phenomenon.

Because the temperature of the self-adhesive materials stored in the printing factory was low, the adhesive on the self-adhesive materials was frozen, which caused the above-mentioned problems such as poor die-cutting waste discharge and flying labels. Finally, it is recommended that the printing factory increase the workshop temperature (above 10°) and locally heat the unwinding, die-cutting and other parts of the materials. After the above adjustments, when the original batch of self-adhesive materials were used for label production, the flying labels and poor die-cutting waste discharge disappeared.

Case 2: The label warps and falls off when the product is shipped out

In winter, a northern daily chemical factory was labeling plastic bags of washing powder in a workshop with a labeling environment temperature of more than 12°C. After the labeling was completed, the product was immediately pulled into an open-air warehouse for storage. At this time, the temperature of the storage warehouse was below 0°. After a period of time, it was found that the label of the product had serious warping and even fell off when it was shipped out.

The labeling process of self-adhesive labels can be divided into two stages: one is that the label is initially combined with the surface of the object under pressure; the other is that the pre-coated glue on the self-adhesive material flows slowly and fully combines with the surface of the object to be labeled to exert the best adhesion. However, the fluidity of the glue is greatly affected by the change of ambient temperature. The lower the ambient temperature, the slower the glue fluidity. Therefore, the crux of the warping and even label shedding phenomenon in the daily chemical factory is that after the labeling of the washing powder plastic bag is completed, sufficient conditions are not provided for the viscosity of the self-adhesive material to be exerted.

Related experiments have shown that it usually takes 24 hours for the glue to exert the best adhesion after the labeling is completed. Therefore, it is recommended that the daily chemical factory store the products indoors (at 12°C) for one day after labeling and then transfer them to an open-air warehouse for storage. As a result, the problem was solved.

Case 3: Large temperature difference between indoor and outdoor, improper use of self-adhesive labels

A blow molding factory in the north set the temperature above 20°C when labeling and storing products in the warehouse. In accordance with industry requirements, the labeled products were placed for 24 hours before shipment. However, when the end customer received the goods, they found that all the labels on the surface of the products were wrinkled.

The indoor temperature of the blow molding factory was above 20°C when labeling and storing labels, while the outdoor temperature reached -30°C at that time, and the temperature difference between indoor and outdoor reached about 50°C. At that time, the back sticker of the label was made of high-density polyethylene (HDPE) and the label material was coated paper. In such a large temperature difference environment, the shrinkage of the back sticker was much greater than that of the label, so the label on the surface of the product would be seriously wrinkled.

Finally, the blow molding plant used label materials with a shrinkage ratio close to that of the HDPE material of the back sticker, which reduced the probability of this problem.

From the above three cases, it can be seen that the following points should be taken care of when storing self-adhesive labels:

(1) Before processing or labeling, the label should be placed in the labeling environment for more than 24 hours to allow the temperature of the label itself to rise, so that the viscosity and processing performance can be restored;

(2) When using self-adhesive labels, the temperature of the processing workshop should be increased (above 10°), and the unwinding, die-cutting and other parts of the material should be locally heated;

(3) Label materials with a shrinkage ratio close to that of the back sticker material should be used to prevent problems such as wrinkling due to different thermal expansion and contraction properties of the material in an environment with a large temperature difference;

(4) It is not advisable to immediately place a container or product that has just been labeled in an environment with a large temperature difference, otherwise the viscosity of the glue will be affected.