Self-adhesive label using common fault analysis

It is believed that the vast majority of people were still unfamiliar with sticker labels 20 years ago, but today we use self-adhesive labels on the packaging of various commodities in our lives. It can be said that adhesive labels have been increasingly used in medicine, daily chemical, clothing, electronic products and other industries that are closely related to our daily lives. Although people are no longer unfamiliar with self-adhesive labels, we are often seen as professionals engaged in adhesive production and research because of the lack of understanding of the properties of adhesive labels and the use of self-adhesive labels. The malfunction caused by the irregular behavior. Below, I share with you some of the cases encountered in daily work due to improper use of self-adhesive labels.
Case 1: Labels drop after labeling

A manufacturer of ice glutinous rice needs to use self-adhesive labels on the lid of the plastic ice box. Because the ice cube is stored in a plastic box, it should be stored at minus 38 degrees Celsius and refrigerated at low temperatures. The customer removes the product from the cold storage directly before shipment and immediately labels the lid. As a result, all the labels that had been attached after several hours fell from the lid.

Failure analysis: This failure is mainly caused by the customer's unclear understanding of the performance of the adhesive adhesive. To clearly analyze the cause of the failure we must first understand several definitions of adhesives. They are: initial viscosity of the adhesive, final viscosity, minimum labeling temperature, and temperature use range.

Microscopically speaking, the surface of any substrate to be attached can be regarded as a rough surface. After the sticker is affixed to the surface of the object to be adhered, the adhesive just touching the surface of the labeling material has not been completely leveled on the surface of the object to be adhered, and the adhesive force between the adhesive agent and the surface of the object to be adhered is weak. Viscosity is called the initial viscosity of the adhesive.

Within a certain period of time after labeling (generally 24 hours after labeling), the adhesive is completely leveled on the surface of the substrate to be attached. The binding force of the adhesive to the surface of the object to be attached is maximized, and the viscosity exhibited by the adhesive at this time is called the final viscosity of the adhesive.

The minimum temperature that the adhesive can withstand when labeling is called the minimum labeling temperature of the adhesive. That is to say, labeling must be performed at a temperature above the minimum labeling temperature in order to maintain good flowability of the adhesive. If the temperature at the time of labeling is lower than the minimum labeling temperature, the adhesive will be frosted and thus the adhesiveness of the adhesive on the surface of the substrate to be attached will cause the viscosity of the adhesive to decrease.

After the label is affixed to the substrate for a period of time, after the adhesive has reached a final viscosity, the temperature range that can be tolerated during use is called the range of use temperature of the adhesive. The temperature range of use of the adhesive is wider than the range of the lowest labeling temperature.

The minimum labeling temperature for adhesives used in adhesive labels used by Hing Ling is no more than 10 degrees Celsius, and the final temperature for use in adhesives is minus 40 to 90 degrees Celsius. The main reason for the label falling is that the initial labeling temperature (minus 38 degrees Celsius) is lower than the minimum labeling temperature of the adhesive (above 10 degrees Celsius). In this case, the adhesive can be frozen and lost its fluidity. Good leveling on the surface of the object to be adhered to, causing the label to fall due to a drop in viscosity.

Solution: After you know the cause of the failure, there are two ways to solve it.

First, use adhesives that are suitable for ultra-low temperature labeling, but doing so will increase costs significantly.

Second, change the labeling process, Hing Ling Ling factory first in the environment above zero degrees Celsius to the label on the lid of the plastic box above. After 24 hours, the adhesive will reach the final viscosity and then put the labeled plastic box into the cold storage. Because the adhesive has reached the final viscosity after the use of temperature range of minus 40 degrees Celsius to zero 90 degrees Celsius. Therefore, it can completely adapt to the low-grade environment of minus 38 degrees Celsius, and the phenomenon of label dropping has been completely solved.

From this case, we can see that it is very important to understand the initial viscosity, the final viscosity, the minimum labeling temperature, and the use temperature range of the adhesive during the application of the adhesive label. Reasonable application of these features can save costs and reduce the occurrence of faults during use.

Case 2: Tyre labeling after labeling

Once a tire manufacturer had dropped after the label was applied, the customer stuck the labels on two different brands of tires. One type of tire has a drop on the label and the other is not the problem.

Failure analysis: after the phenomenon investigation revealed that there is no failure of the tire surface is relatively smooth, there is no tire thorn (a small tire on the surface of the tire). The failed tire surface has a lot of fetal thorns. It is understood that the method of labeling by customers is manual labeling and labeling is very fast, and the labeling gesture is basically a way to peel off the label and go to the tread. Based on the above phenomenon, we analyzed two main reasons that caused the tag to drop: on the one hand, there are many standing thorns on the tread. On the other hand, since the label is not fully pressed when posted, the label that is affixed to the homeopathy is equivalent to being hung on the tire surface and being placed on the top of the spines. More than 80% of the plastic surface of the label is not attached to the body (tread), so the label of the label will certainly fall.

Solution: Improve the manual labeling method. When labeling, try to press the label as far as possible so that the adhesive is in contact with the surface of the substrate to be attached. Customer troubleshooting through improved labeling methods.

Case 3: When the label is automatically labelled

There was a company that had frequent occurrences of irregular breaks in the label's backing when it was labeled with an automatic labeling machine (this phenomenon is often referred to as a labeling breakage), giving this company a great deal of productivity. influences.

Failure Analysis: The following reasons are usually caused by this failure:

First, the label bottom paper edge crack

After the adhesive label is processed into the finished product by die-cutting, the back-end paper will generally be left wider than the label. This is to facilitate labeling when the customer labels the label. It is easy to split the bottom edge of the label into small tears in the process of label packaging, shipping and handling. The automatic labeling machine has a certain tension when labeling, and the label with a crack at the edge of the bottom paper is easily broken under the action of the tension to cause the labeling and breaking. In addition, there are also situations where the roller adjustment on the automatic labeling machine is inappropriate and the backing paper on the edge of the roller fracturing label causes a label breakage. In general, the label-breaking band caused by the roller crushing the backing paper is relatively regular.

Second, label rewinding caused by glue

If the finished product label is rewound too tightly, the adhesive in the adhesive will be squeezed out to cause bleeding, and the oozing glue will stick to the back of the base paper so that the entire roll label cannot be easily released. This is especially true in summer. If the label is relatively narrow, the tensile strength of the backing paper per unit area will not be too great. Automatic labeling machine has a certain tension in the labeling process. When a roll of label with glue penetration is used for automatic labeling, it is very likely that the label-removed base paper is pulled off under the tension of the labeler and the tension from the inside of the roll during the labeling process. Caused labeling broken tape. The label-breaking zone caused by this situation is irregular because the tension is broken, but the fracture surface is relatively homogeneous.

Third, poor die cutting

The quality of die-cutting also has a great influence on whether or not it is easy to break during automatic labeling. If the die-cutting pressure is too large, the backing paper is cut through and the tensile strength of the backing paper is reduced, resulting in the labeling breakage. The faults caused by bad die cuts are relatively uniform at the bottom of the label, and the gap is at the position of the die cut line.

Fourth, the release layer is destroyed

If the release liner (usually a silicone oil layer) of the bottom paper is damaged, it will also result in a label breakage. In this case, the broken surface of the bottom paper is serrated. Caused by the destruction of the layer caused by the raw material production coating defects, and at the same time in the printing factory inspection of the standard process due to improper practices may also cause the release layer scratches.

solution:

According to the above-mentioned several reasons for the number of seated to solve the problem, sometimes the fault of the labeling broken belt is not caused by an isolated cause, but the above several causes combined. For example, the company mentioned above is a label-breaking band caused by two reasons of poor die-cutting and rewinding.

Case 4: Dislocation of Thermal Label Printing

Once, the customer reported that it was also the product of Glassine. The blue base paper had no problem on the thermal printer but the white base paper had the problem of misalignment. The main manifestation is that after printing a few sheets, the printing position gradually shifts forward or backward.

Failure analysis:

Thermal printers use a sensor to scan the distance between the labels to control the paper feed. The light intensity of the sensor can be adjusted. The blue backing paper and the white backing paper have different light transmittances. The customer's printer used blue backing paper to print, and the light intensity of the photosensitive head was adjusted higher. After replacing the label with white backing paper, the step scan was unstable because the white backing paper had higher light transmittance than the blue backing paper. In order to confirm this judgment, let the customer cover the photoreceptor with a small piece of white paper, which artificially reduces the light intensity of the photoreceptor. On the machine print labels print step is very stable.

solution:

The thermal intensity of the thermal head of the thermal printer is adjustable. When using a material with a different color from the previous backing paper, if the step scan is unstable, you can try to adjust the light intensity of the photosensitive head to solve this problem.

The above mentioned are just a few glitches that often appear in daily production applications of adhesive labels. I believe that with everyone's constant understanding of the use of self-adhesive labels, we can make better use of adhesive labels to reduce the frequency of failures.



Source: Bison