How to judge the quality of pressure-sensitive adhesive?

Take organic pressure-sensitive adhesive as an example: the quality of pressure-sensitive adhesive can be judged from five aspects, including bonding strength, drying speed, viscosity, solid content and pH value.

① Bonding strength

Pressure-sensitive adhesive and pressure-sensitive adhesive glue must first have sufficient bonding strength to adhere to the bonded parts and have certain uses. The industry judges whether the bonding strength of pressure-sensitive adhesive and glue is qualified by tearing the two bonded materials along the bonding interface. If it is found that the bonded materials are damaged after tearing, it proves that the bonding strength is sufficient; if only the bonding interface is separated, it indicates that the adhesive strength is insufficient.

② Drying speed

When purchasing pressure-sensitive adhesive, choose the appropriate pressure-sensitive adhesive glue according to the bonding process. If the product is not suitable for the process, the pressure-sensitive adhesive can be diluted by adding solvent. Generally, it can be used directly. The machine assembly line coating production is fast, and the dilution scheme is often used to facilitate glue coating. At the same time, baking and tunnel furnace heating are used to accelerate the volatilization of solvents to save time and cost.

③ Viscosity

Viscosity is the most important factor affecting the quality of adhesives. If the viscosity is too high, the coating will be thicker, the glue consumption will be large, the drying will be slower, and the wetting and penetration of the adhesive on the surface of the adherend will be affected, which will directly affect the bonding strength; if the viscosity is too low, the coating will be thinner, the drying will be too fast, and problems such as poor bonding will occur.

④ Solid content

It is also one of the important factors affecting the quality of pressure-sensitive adhesives. The higher the solid content, the stronger the adhesion and the faster the drying speed. The solid content also has a direct impact on the viscosity and drying speed of pressure-sensitive adhesives.

⑤ 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 are more alkaline. High alkalinity will not only corrode the operators and equipment, but sometimes corrode the adherends, forming scars that affect the appearance. Therefore, when purchasing adhesives, the impact of pH value on the product should be considered.