Judging the quality of pressure-sensitive adhesive
Ordinary manual bonding workers determine the quality of water-based pressure-sensitive adhesives. Generally, they can be measured in terms of adhesion strength, drying speed, viscosity, solid content, and PH value.
1. solid content
The solid content is also one of the important factors affecting the quality of water-based pressure-sensitive adhesives. The higher the solids content, the stronger the adhesion and the faster the drying speed.
2. pH value
Synthetic resin adhesives are mostly weakly acidic and will not have a negative impact on the bonding process. However, water glass and starch adhesives have higher alkalinity, and higher alkalinity will not only cause corrosive effects on operators and equipment, but also corrode the adherends, forming spots that affect appearance. Therefore, the effect of pH on the product should be considered when purchasing adhesives.
3. Adhesive strength
Water-based pressure-sensitive adhesive must first have sufficient adhesive strength to ensure the normal use of the object after bonding. To determine whether the adhesive strength of the adhesive is qualified, you can tear the two pieces of adhered material along the adhesive interface. If the adhered material is damaged after tearing, it proves that the adhesive strength is sufficient; if only the adhesive interface is separated, it indicates that Adhesive strength is insufficient.
Viscosity is an important factor affecting the quality of adhesives. If the viscosity is too large, the coating will be thick, the amount of glue consumed, and the drying will slow down. It will also affect the wetting and penetrating effect of the adhesive on the surface of the adherend, and then directly affect the bonding strength; if the viscosity is too small, The coating is thin, dries too quickly, and is prone to problems such as poor adhesion.
When choosing water-based pressure-sensitive adhesive, you must measure whether the drying speed matches the bonding process. The general manual bonding process is slow and requires a long initial drying time, while the machine bonding process is fast and requires a short initial drying time. As far as the dry time is concerned, in most cases, the sooner the better, so as to be able to enter the next process as soon as possible.