Some common problems in the use of self-adhesive materials (2)
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With the continuous development of China's economy, self-adhesive labels have been widely used in various fields. However, due to the uneven economic development in China, the technical level of self-adhesive printing enterprises in many regions is relatively backward, and is often plagued by some problems. Therefore, in this article, I will share with you some of the problems that are easily encountered during the processing and use of stickers and give corresponding solutions.
Printing off ink
The phenomenon of ink drop phenomenon is relatively low in the printing of paper self-adhesive materials, which is more common in film materials, mainly due to the unstable surface tension of film materials. Under normal circumstances, the reason why the film material is printed off ink is low surface tension of the film material, poor UV curing, and excessive use of the ink additive.
1. Low surface tension of film material leads to ink loss
In general, the surface tension of the film-like material needs to be more than 38 dynes to ensure normal printing, and to make the ink firmly adhered, it is required to reach 42 dynes or more. If the ink is lost during the printing process, the Dyne pen can be used to test the surface tension value of the material. If it is lower than the above standard, it is recommended to use the online corona or the primer to increase the surface tension of the film material. In order to achieve better ink adhesion. If there are no conditions to solve the problem by the above two methods, you can also use low surface energy ink to try to solve. Many ink manufacturers currently offer inks specifically for low-surface energy materials, and printing companies can test to find an ink that matches the label material used to solve this problem.
2. Poor UV curing leads to ink loss
The ink drop also has a lot to do with the curing effect of the UV ink. If the power of the UV lamp is insufficient, or if the printing speed is too fast, a "fake dry" phenomenon will occur, which can easily lead to ink loss. The so-called "fake dry" means that the surface of the ink has dried/cured, but the interior is not completely dry.
Dry / cure. It should be particularly noted here that the ink drop caused by this phenomenon occurs mostly in the printing of large-area solid patterns. This is because the amount of ink used in the solid pattern is large, and the inside of the ink layer is not easily cured completely. In addition, sometimes the ink printed at the same time is only a certain color drop ink is more obvious, the most common is the black ink off the ink is serious. This is because UV light is more difficult to penetrate the black ink layer, and in most cases the black ink is arranged to be printed in the last color group, the total curing time is the shortest, and it is not easy to cure completely.
In case of such problems, you can first check if the UV lamp has exceeded the rated service life. If it is exceeded, you need to replace the lamp. If the UV lamp is in the normal service period, then the power of the UV lamp should be insufficient, and the power of the UV lamp can be appropriately increased, or the printing speed can be lowered.
However, for film-type self-adhesive materials, such processing may cause new problems - when the printing speed is too low or the UV lamp power is too high, it is likely to cause the film-type self-adhesive material to be subjected to heat per unit time. Larger and deformed. In case of such problems, the amount of ink supply can be appropriately reduced, and the printing speed or the power of the UV lamp can be appropriately increased to ensure the ink is completely cured. If the amount of ink supply is reduced and the printing in the field is falsified, it can be solved by two printing methods if necessary.
3. Insufficient amount of ink additive leads to ink loss
The winter weather in the north is relatively cold. Some printing companies will encounter problems of thickening, viscous, and poor ink in the production process. Many operators will use the method of adding ink to increase the fluidity of the ink. However, once the varnish is added too much, it is easy to cause ink loss. In general, the addition ratio of varnish is 3% to 5%, and if it exceeds this range, it needs to be carefully added.
Labeling
Labeling and lifting is a problem often encountered by users of self-adhesive labels. It is divided into two parts: labeling immediately after lifting and labeling for 24 hours. Immediately after labeling, the so-called uncovering, generally speaking, has a great relationship with the adhesiveness of the adhesive in the self-adhesive label; and the reason for the lifting after 24 hours of labeling is complicated. The causes of labeling and lifting are usually caused by incorrect selection of self-adhesive materials, poor adhesion of adhesives, poor cohesive force, unreasonable process settings, and unreasonable use by customers.
1. The selection of the small bottle of self-adhesive material leads to the labeling
Bottles with a diameter of less than 30 mm are often referred to as vials. If the selected label material itself has a large stiffness, it is easy to warp. Therefore, the self-adhesive label applied to the vial generally adopts a strong adhesive adhesive, and the adhesive force on the bottle body is far greater than the elastic force of the label surface material itself to resist deformation, so as to ensure that the labeling is not warped after labeling. .
There are many kinds of self-adhesive materials on the market, most of which are not recommended for small bottles, but some end users have insufficient expertise and incorrectly selected non-applicable label materials, which leads to label lifting after labeling. Under normal circumstances, the bottle body labeling caused by the wrong selection of the self-adhesive material is uplifted, and it will start several hours after the labeling, and the degree of lifting will become larger as time goes by.
In view of this, the label printing company must carefully understand the customer's labeling body when accepting the self-adhesive label order. If the customer is found to be applied to the small bottle body, then it must consult with the professional self-adhesive material supplier. A material that best suits the customer's application to process the label.
2. Adhesive viscosity is poor, causing labeling
Some self-adhesive materials will fade quickly after leaving the factory for a period of time. Coupled with the self-adhesive label finished products, the end user may not be used in the first time, and the labeling phenomenon will occur when labeling. For this reason, the labeling is uplifted, usually there is no problem with the labeling of the new material processing, and the labeling of the old material processing may cause problems, or the inventory label may have problems, and the viscosity of the new and old label materials is greatly different. . The labeling and lifting caused by this reason usually starts within a few hours after labeling, and the longer the time, the more serious it is. In the event of such problems, the raw material supplier can be complained about the claim and the replacement of qualified materials is required.
3. Adhesive cohesive force leads to labeling and lifting
Generally speaking, as long as the label is not up to 24 hours after labeling, there is basically no big problem. Because the adhesive has completely combined with the surface of the sticker after 24 hours of labeling, the maximum viscosity of the adhesive is achieved. However, sometimes the label does not pick up after 24 hours of labeling, but the stock has been tilted after a long period of time. Why is this?
Usually, when we look at the attached object and the label, we will find that some of the adhesive on the label remains on the surface of the object. This is due to insufficient cohesive force of the adhesive, resulting in a period of time after labeling. The adhesive is separated under the tension of the label surface itself. A portion of the separate adhesive remains on the label while the other portion remains on the surface of the sticker. In this case, we can ask the supplier of self-adhesive materials to test whether the cohesive force of the adhesive meets its quality standards.
4. Unreasonable process setting leads to labeling and lifting
Some labels with glazing process, if they are attached to the object, that is, the label is wrapped around the sticker, there is no gap in the middle, and the two sides are stacked together, because the varnish itself contains certain silicone oil. Therefore, it is easy to lift up after the label is attached. Therefore, the labeling process is not recommended for the glazing process, and it is best to change to the lamination process.
5. Unreasonable use of customers leads to labeling and lifting
Some customers put the product in the cold storage with low temperature immediately after labeling; some customers will label the object from the cold storage and then label it on the surface of the sticker; Some customers will label the steel or iron plates placed in the open air, or label them in a dusty environment. All of these are unreasonable applications, and it is very easy to cause the label to rise.
Regardless of whether it is a label manufacturer or an end user, you should select the most suitable label according to the actual application of the label. If you do not understand the relevant knowledge, you can ask a professional self-adhesive material supplier to help solve the problem and find the most suitable one. Glue material.
The above analysis is a few common problems in the application of self-adhesive materials. Of course, there are still many problems encountered in actual production and application. However, due to limited space, I can't explain them one by one. I hope that there will be opportunities in the future. Everyone exchanges a lot. In addition, there are many solutions to the same problem. I believe that there are many better solutions for the problems mentioned in this article. I hope this article can play a role in attracting more and more peers to accumulate in their own practice. Valuable experience to share with you.