Labels peeling off? The truth behind it will surprise you!

The self-adhesive label material is usually composed of three parts: backing paper, tissue paper and adhesive, among which the surface of the backing paper is oily, which has an isolating effect on the adhesive and can ensure that the tissue paper is easy to peel off from the backing paper; Tissue paper is the main carrier of label printing content, which can be divided into coated paper, thermal paper, PET, PVC, etc. according to its different materials.
Affected by subjective and objective factors, self-adhesive labels often produce problems such as warping, wrinkling, bubbles, and broken liner paper in the labeling process, which are complained by customers, causing headaches for label printing companies. Among them, warping is the most common in the labeling process. In this article, the author systematically analyzes the causes of the problem of sticker label labeling warping based on practical work experience, and gives solutions, hoping to provide some help to readers.
The main influencing factors of labeling warping
01
The effect of stickiness and product matching of self-adhesive labels on labeling warping
If the glue of the self-adhesive label material is not sticky enough, it will definitely lead to the problem of labeling warping. In addition, due to the large number of self-adhesive label materials, there is a problem of whether different labels and self-adhesive label materials match each other during labeling, such as AW4200A, AW3209 and other self-adhesive labels cannot be affixed to bottles with a diameter of less than 3cm, and hot-melt adhesive labels cannot be affixed to PVC adhesive labels.
The above precautions have been clearly written in the technical parameters of self-adhesive label materials, so it is recommended that label printing companies must carefully read the technical parameters of the product when choosing self-adhesive label materials, and it is recommended that when sending samples to end users for confirmation, they also attach the product technical parameters of self-adhesive label materials to avoid unnecessary risks caused by misuse by end users.
02
The effect of the flatness of the surface material of the self-adhesive label on the warping of the label
For self-adhesive label materials, the smoothness of the self-adhesive label surface is a key factor affecting the smoothness of the overall material, and the smoothness of the overall material is an important indicator to ensure the printing quality. Therefore, during the labeling process, we must pay attention to whether the surface material of the self-adhesive label is flat, especially when the label is laminated, we must pay attention to the tension of the lamination should not be too large, otherwise too much tension will cause the label to curl upwards, causing the label to warp.
03
The effect of label design on label warping
Labels should be designed to avoid overlapping ends as much as possible. If it is unavoidable, then the method of cold lamination should be avoided, and the overlap part should not be printed or varnished.
The following points should be paid attention to when labeling the label is overlapped: (1) If the label must be laminated, then the label must be treated with corona after lamination, so that the surface of the film can be greater than 38 dynes, so that normal labeling can be achieved; (2) When printing, the lap joint should be blanked, and the printing surface can be 1~2 lines larger to the lap position, so as to ensure that the white is not exposed after labeling; (3) For labels that need to be varnished, the original full plate varnishing can be changed to partial varnishing, and the overlap labeling is not varnished; (4) Pay attention to the curing degree of UV ink, because the surface energy of the over-cured ink layer will be reduced, affecting the adhesion of the next layer of ink and the adhesion of the adhesive.
04
The effect of the material of the object being labeled on the warping of the label
Due to the different materials of the pasted objects, their surface energy will be different, so the effect of the same self-adhesive label after labeling will also be different. Normally, the surfaces of different materials can be compared as follows: stainless steel> glass> PET>PP> PE.
In addition, the surface of the same material will also be different due to different processing processes, such as siliconized glass bottles, plastic bottles with different surface roughness, etc. Therefore, for the object or bottle body with different surface energy, it is necessary to use different adhesive labels to match.
05
The influence of the shape of the object on the warping of the label
In order to achieve the ideal labeling effect, the labeling surface of the object to be applied should be a flat surface after unfolding. If the labeling surface of the object to be applied is curved in both directions after unfolding (spherical labeling surface), it is difficult to achieve the ideal labeling effect. Therefore, the bottle body should be designed to avoid such a shape as much as possible, or try to avoid such a position when labeling.
In addition, due to the pressure of production costs, blow molding plants often reduce the weight of the bottle body, so that the bottle body becomes thinner, resulting in large deformation of the bottle body before and after filling, and it is impossible to exert large labeling pressure, such as when hot filling 30°C~40°C liquid after labeling, the bottle body part will be raised and deformed, and the bottle body will retract after cooling, resulting in the undesirable phenomenon of labeling and warping.
06
The effect of the surface condition of the object to be labeled on the warping of the label
The roughness of the surface of the object has a great impact on the labeling effect, and the rougher the surface of the object, the more likely it is to cause the problem of labeling warping. In addition, if there are impurities such as oil, water droplets, and dust on the surface of the object, it is equivalent to adhesive sticking to these impurities, rather than sticking to the surface of the object, and it is easy to warp the label.
In addition, whether the surface of the object to be labeled has been treated with special processes may also affect the final labeling effect, such as small diameter glass bottles in the process of filling potions, because the medicine is not allowed to hang on the wall, the surface of the bottle will be cleaned with silicon water in advance, if there is a lot of silicon residue after cleaning, then the label will have the problem of labeling after labeling.
07
The influence of labeling environment on labeling warping
Normally, the labeling temperature requirements generally include four aspects: label temperature, object temperature, labeling ambient temperature, and storage temperature within 24 hours after labeling, as follows:
(1) The technical parameters of each self-adhesive label material are clearly marked with the minimum labeling temperature and use temperature range, such as the minimum labeling temperature of NW5539 label products is 10°C, and the use temperature range is -15°C~65°C.
(2) When labeling, the ambient temperature must meet the minimum labeling temperature of the label, only in this way can the label adhesive flow normally and exert normal stickiness.
(3) The surface temperature of the object to be applied must be above the minimum labeling temperature, so that the adhesive with fluidity will not deteriorate or stop flowing because it is attached to the low-temperature surface, resulting in a decrease in viscosity.
(4) The ambient temperature of storage after labeling is also very important, in order to maintain the fluidity of the adhesive and convert the labeled adhesive from initial viscosity to final viscosity, it needs to be completed in an environment above the minimum labeling temperature.
Different labeling processes can also have an impact on labeling warping problems. For example, an ice cream brand fills the ice cream plastic box with ice cream at an ambient temperature of 10 °C, automatically fills the lid, and then automatically labels the lid and around the box, and finally freezes it in an ambient temperature of -15 °C, and then transfers it to a large cold storage for storage after 1~2 hours.
In order to solve this problem, the company labeled the plastic box that needed to be filled with ice cream on the second day in advance, and then poured, capped, and quick-frozen after 24 hours of labeling, and transferred to a large cold storage for storage, which solved the problem of label warping well.
For different surfaces and labeling requirements, different labeling mechanisms should be selected, commonly used such as sponge wheels, pulleys, labeling plates, etc. In addition, the labeling machine should apply appropriate labeling pressure to the label to ensure that the label can fit perfectly with the object being applied.
When the labeling pressure is insufficient, such as using a soft brush, a labeling plate that is too soft, or the spacing between the sponge wheel and pulley and the bottle body is too large, the label will warp due to insufficient labeling pressure. In addition, if the labeling mechanism is aging, it will affect the labeling pressure, which may cause labeling warping problems.
Labeling and uplifting customer cases
In 2021, the PE self-adhesive label of a company had a warping phenomenon during the labeling process, which urgently needed to be solved. It was learned from the enterprise site that after the company took out the sticker from the cold storage, it labeled when there was still condensation on the surface of the sticker, and immediately put the product in the cold storage with a very low temperature after labeling, which did not make the label storage temperature reach more than 10 °C. Therefore, we conclude that the labeling warping phenomenon is caused by environmental problems.
The normal operation is: the label must be stored in an environment above 10 °C 24 hours before labeling, because the adhesive of this label only has good fluidity in an environment above 10 °C, and the adhesive can be played normally.
According to the suggestion, the company immediately made improvements and adjusted the place where the labels were stored to ensure that the temperature of the stored labels was above 10°C. After post-tracking, no labeling problems were found in the labels produced by the company.
Whether it is a label printing enterprise or an end user, it should choose the most suitable self-adhesive label material according to the actual application of the label, and pay attention to the impact of environmental temperature and humidity on the label. Only by considering multiple aspects can we improve the labeling quality of products and make them more beautiful.