This is because polyamide resin is the primary matrix that is utilized in the production of high temperature resistant hot melt adhesive. Polyamide resin is a type of linear thermoplastic resin that possesses a large number of amide groups that are repeated along the main chain of the molecule. This gives the polyamide resin its distinctive structure. When compared to other thermoplastic resins, this one stands out due to the fact that the processes of melting and curing the resin both take place within the same limited temperature range. In other words, the melting and curing processes of the resin happen simultaneously. Because of this, it makes no difference whether the resin is heated or cooled; the results are the same regardless of the direction in which the temperature is applied to the material. What are the most important ingredients that go into the making of a hot melt adhesive that is able to perform its intended function even after being subjected to high temperatures?It is done in this manner in order to ensure that it will adhere firmly to the surface that it has been applied to. In addition to this, it is able to keep its excellent bonding properties even at temperatures that are relatively close to those at which it begins to become pliable. This is something that it is capable of doing even when it is heated to a relatively high degree.

 

When the hydrogen that is already present on one segment of the amide group of the polyamide resin combines with the electron-donating carbonyl group that is already present on another segment of the amide group, a powerful hydrogen bond has the potential to be formed. These qualities will improve as the resin moves in the opposite direction of decreasing in molecular weight. This will make the resin more desirable overall. This is due to the fact that polyamide has a higher molecular weight than the majority of other materials. Within this range, the vast majority of the occurrences can be found. The matrix of hot melt adhesive is typically composed of polyamide resin, which is obtained primarily through the polycondensation reaction of dimer of unsaturated fatty acid and diamine. This resin is put to use in the manufacturing of hot melt adhesives. This reaction is referred to as a polycondensation in the scientific community. As a direct result of this, the resins that were produced have very different molecular weights, and as a direct result of this, their melting points are also very different. The majority of the time, the process that involves mixing ethylenediamine and hexanediamine together is the one that is carried out.

 

Why is it that hot melt adhesives have such a terrible ability to stick to different surfaces?
1. The application of the hot melt adhesive must be done in a manner that is suitable for the kind of material that is being adhered, and this is the first rule that must be followed.If the wrong kind of hot melt adhesive is used to bond the material in question, the bonding process will not be successful;
2. The temperature is not high enough to reach the point of melting, so the point of melting is not reached.Because the temperature is not high enough, the hot melt adhesive does not fully melt, and the connection cannot be produced well. 7.A change in temperature will cause a change in the physical state of the substance, but it will have no effect on the chemical properties of the substance at any temperature.Because they do not have a complete understanding of hot melt adhesives, users of hot melt adhesives frequently run into a variety of problems during the manufacturing process. These problems can range from ineffectiveness to safety concerns.When working with hot melt adhesives, one of the problems that may arise is the phenomenon of the glue not sticking, which may occur at any stage of the process.An explanation of a method that can be utilized to improve the bonding strength of hot melt adhesive is provided below.Reduce the abrasiveness that is already present on the surface.
The roughening of the surface is beneficial because it improves the degree of infiltration of the liquid hot melt adhesive onto the surface and increases the contact point density between the liquid hot melt adhesive and the material that is adhered. In other words, the roughening of the surface makes it easier for the liquid hot melt adhesive to adhere to the surface.The surface should be roughened in order to improve the degree of infiltration of the liquid hot melt adhesive onto the surface. This will be beneficial.This is due to the fact that a surface is said to have good adhesion when the hot melt adhesive successfully infiltrates the surface of the material that has been adhered (contact angle of 90 degrees)..

 

tpu hot melt adhesive film

 

2.The surface treatment of aluminum and aluminum alloys will also have an effect on the bonding strength. This is because of the same weak boundary layer that affects the first point.It is desirable for there to be crystals of aluminum oxide on the surface of the aluminum, and this is something that should be hoped will happen.The layer of aluminum eva hot melt adhesive film oxide that covers naturally oxidized aluminum is quite flaky, and the surface of naturally oxidized aluminum has a surface that is quite uneven.Both of these circumstances do not encourage the formation of bonds in the desired manner.The goal of this process is to promote the growth of crystals on the surface of the aluminum that are composed of aluminum oxide.Penetration
The bonded joint will typically become infiltrated into other substances with a low molecular weight as a result of the action of the atmosphere that is surrounding the bonded joint.For instance, if the joint is placed in a humid environment or is submerged in water, water molecules will be able to pass through the adhesive layer, which will ultimately lead to the joint failing.When the layer of polymer adhesive is first submerged in the organic solvent and then allowed to dry after being immersed in the organic solvent, molecules of the organic solvent are able to pass through the layer of polymer adhesive.Next, these molecules make their way into the interface that is present between the adherend and the adhesive layer, which causes a weakening of the adhesive layer and, ultimately, the rupture of the bond that was formed between the adherend and the adhesive layer.

 

4. This is due to the fact that these smaller molecules do not have a high level of compatibility with the larger macromolecules that make up the polymer.If the migrated small molecules accumulate on the interface, the hot melt process will be hindered.The fact that the bond that is supposed to form between the adhesive and the material to which it is applied does not function correctly is the fundamental cause of the issue that has arisen.Pressure
When the bonding process is underway, applying pressure to the bonding surface will make it simpler for the hot melt adhesive to fill the voids on the adherend's surface.In addition to this, it will make it possible for the adhesive to flow into deep holes and capillaries, which will result in a reduction in the total number of bonding defects.If you apply pressure to it, it will begin to flow po hot melt adhesive film excessively, which will ultimately result in there being no glue left for you to use.Because of this, it is essential to make use of pressure whenever the viscosity is particularly high.This not only promotes the escape of the gas that is present on the surface of the adherend, but it also contributes to the reduction in the number of pores that are present in the region that is being bonded.