Do you know the bonding construction knowledge of customized Polyurethane adhesive? Let's take a look at it briefly!
1. Glue
Coating (gluing) methods include spraying, brushing, dipping, roller coating, etc., which are generally determined according to the type of glue, viscosity and production requirements. The key is to ensure that the glue layer is uniform, without bubbles, and without lack of glue.
The amount of glue applied (actually related to the thickness of the glue layer) is also an important factor affecting the shear strength, and the shear strength is usually higher within a certain range. If the adhesive layer is too thin, the adhesive cannot fill the uneven gaps on the surface of the substrate, leaving vacancies, and the bonding strength is low. When the thickness of the adhesive layer increases, the bonding strength decreases. It is generally believed that when the lap shear sample bears the load, the adherend and the adhesive layer deform themselves, and the adhesive layer is destroyed into a peeling state. The peeling force reduces the apparent shear strength value.
2. Let it dry
For the solvent-based customized Polyurethane adhesive, it needs to be left in the air for several minutes to tens of minutes after the glue is applied to make most of the solvent in the adhesive volatilize, which is conducive to improving the initial adhesion. If necessary, it should be properly heated and air-dried (such as composite film lamination process). Otherwise, due to the large amount of solvent remaining in the glue, the curing process will easily form bubbles in the glue layer, which will affect the bonding quality. For solvent-free customized Polyurethane adhesive, the adherend can be bonded after the glue is applied.
3. Bonding
This step is to attach the adhesive surface of the adherend that has been coated with glue. You can also use a clamp to fix the adhesive to ensure that the adhesive surface is fully attached and positioned. If necessary, apply a certain pressure to make the adhesive better Produce plastic flow to infiltrate the surface of the adherend, so that the adhesive and the surface of the substrate can reach greater contact.
The above is an introduction to the bonding construction knowledge of customized Polyurethane adhesive.