Views: 8877 Author: Site Editor Publish Time: 2022-07-19 Origin: Site
The principle of pur hot melt adhesive cooling and solidification is that the heated pur hot melt adhesive will have an irreversible chemical reaction with the moisture in the air, and the pur hot melt adhesive after solidification will not be affected by high temperature, low temperature, and other environments. Pur hot melt adhesive In fact, it penetrates into the inside of the bonded object and combines with its molecular structure to destroy the surface layer of the object, thereby firmly bonding the two objects. So what can we use to change the stickiness of pur hot melt adhesive?
1. Surface treatment
The surface of many objects is often covered by a layer of oxide, phosphating layer or mold release agent, etc. to form a "weak boundary layer", which will directly affect the bonding strength, so it is best to put the surface of these objects before bonding. The oxide layer, etc. is treated first to improve the bonding strength.
2. Improve surface roughness
The surface of the adherend is too smooth, and the pur hot melt adhesive can penetrate less molecules, thereby reducing the bonding strength. The roughening process of the surface of the object can also affect the adhesion. Therefore, we can also increase the bonding strength of the hot melt adhesive by increasing the roughness of the surface of the bonded object.
3. Adhesive layer thickness
Pur hot-melt adhesive bonding does not mean that the more glue you use, the stronger the adhesion. The thicker the glue layer is easy to produce bubbles, which will cause defects or early fractures, so we try our best to glue The thickness is thinner, so that a higher bonding strength can be obtained. In addition, the thermal expansion of the thick adhesive layer after heating makes the thermal stress caused by the bonding surface relatively large, and it is difficult to achieve the molecular damage on the surface of the bonding site, and the bonding will not be firm.
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