Judging the quality of pressure sensitive adhesive
The quality of water-based pressure-sensitive adhesives can be judged by general manual bonders, which can generally be measured from several aspects such as adhesive strength, drying speed, viscosity, solid content and PH value.
1. Solid content
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.
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 high alkalinity, and the high alkalinity will not only corrode the operators and equipment, but also corrode the adherends and form spots that affect the appearance. Therefore, the effect of pH value on the product should be considered when purchasing adhesives.
3. Adhesive strength
The water-based pressure-sensitive adhesive must first have sufficient adhesive strength to ensure the normal use of the bonded object. To judge whether the adhesive strength of the adhesive is qualified, the two adhered materials can be torn apart along the adhesive interface. If the adhesive material is found to be 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 thicker, the glue consumption will be large, and the drying will be slowed down, which will also affect the wetting and penetration of the adhesive on the surface of the adherend, which will directly affect the bonding strength; if the viscosity is too small, Then the coating is thin, drying too fast, and prone to problems such as poor adhesion.
5. Drying speed
When purchasing water-based pressure-sensitive adhesives, it is necessary to 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. For the drying time, in most cases, the faster the better, so that the next process can be entered as soon as possible.