Many customers will encounter many problems of poor adhesion when using the product. Here Alster provides some solutions for some common reasons so that you can better use hot melt adhesive film in the bonding field. Mainly including the following 5 solutions to the Non-stickiness of Hot Melt Adhesive Film:
Reason 1: Insufficient pressing temperature, pressure and time
Many customers reported that the hot melt adhesive film (hot melt adhesive mesh) could not be adhered, and they thought it was because the adhesive was not good. In fact, when we investigate the cause, we should start with the operation, because most customers are in contact with this type of product for the first time, and the usage method is limited to the written part, and there is no actual operation. Therefore, the hot melt adhesive may not be fully melted due to the low operating temperature, too low pressure and too short time, and of course there is no fastness.
Usually, the operating temperature, time and pressure stated in the technical specification are only reference values. Since the material, thickness and thermal insulation performance of the bonding material corresponding to each use are different, we have no way to write technical specifications for each type of product. It is more necessary for customers to try to test it according to the actual situation of their own materials. When it is found that the material bonding is not firm, the equipment temperature can be increased and tested again.
When the hot melt adhesive film is not operating at a high enough temperature, it has obvious characteristics. You can peel off the loose product to check whether the adhesive layer is intact. If the adhesive layer is intact, you can even peel off the entire hot melt adhesive film. In this case, it is likely that the adhesive layer has not melted due to insufficient operating temperature. If the adhesive layer is broken and cannot be peeled off, or all the adhesive residue is left when peeling, it means that the adhesive has fully melted and you need to look for problems in other aspects.
Reason 2: Understand the equipment you are using
Before pressing and ironing, we must first fully understand the equipment used. Is it because of the equipment problem that the glue is not fully melted? For example, when you use a traditional oil-glue and water-glue laminating machine to operate, friends who do not know the equipment well are likely to have a weak bond. This is because the traditional water-glue and oil-glue laminating machine uses a liquid glue of the self-adhesive type, which only needs a little temperature to be bonded, so the temperature control device is not so strict. In addition, the drum of this type of equipment is large, which will cause serious heat loss, resulting in the embarrassing situation that the temperature on the display panel reaches 180℃, but the actual surface temperature is only 100℃. In the end, the glue layer is not melted and cannot be bonded.
At the same time, if the equipment you use is an iron, be careful not to turn on the steam, because water molecules will lower the temperature of the material, and mixing into the glue layer will also reduce the viscosity of the glue, so pay attention to this when using it.
Reason 3: Not choosing the right type of hot melt adhesive film
When you find that the adhesive is not firmly bonded because of the temperature of your operation, then we have to consider whether the material is not selected correctly. Usually, different types of hot melt adhesive films (hot melt adhesive mesh films) are suitable for different bonding materials. For example, the product with model SWA120 (PA hot melt adhesive mesh film) is more suitable for bonding various fabrics such as cotton, nylon, polyester, and PI film. If you plan to use this type of mesh adhesive to bond metal or TPU film, it may not be firmly bonded.
At the same time, we should pay attention to whether the materials on both sides are not firm or only one side is not firmly bonded, because if the adhesive you bond is only suitable for bonding one side of the material, but not the other side of the material, then there will be a situation of weak bonding. You can peel off the two layers of the problematic product and see which side the middle adhesive layer is attached to, so as to judge which material is not firmly bonded. This is also one of the important methods to analyze the cause of the problem. In short, we must choose a model that is suitable for both sides of the bonded materials to achieve a good bonding effect of the product.
Reason 4: Too high temperature will lead to degradation
If the operating temperature is too high, it will also lead to weak bonding. This is because too high temperature will cause the glue molecules to degrade and no longer have stickiness, even if it returns to room temperature. Of course, this situation rarely occurs. We will also talk about it later in this chapter. As long as the operating temperature does not exceed 60 degrees above the melting point of the product, there will be no problem.
Reason 5: Product debonding after a few days
If the adhesive is very good at the beginning, but debonding occurs after a few days, it is recommended that you change to another type of hot melt adhesive and test it again. This usually happens because the glue crystallizes very slowly. After the initial bonding, the product remains wet and the test will have good adhesion. After a few days, the glue layer has completely crystallized and begins to become catalytic. The two layers of material can be peeled off with a slight tear. This situation is mainly reflected in PES hot melt adhesive film bonding metal products.
If you have problems when using hot melt adhesive film and web, just feel freely to contact Alster for details!
