Butyl glue is a synthetic rubber composed of isobutylene and a small amount of isoprene, which has low breathability and good chemical stability. Pressure-sensitive adhesive is an adhesive that can adhere under slight pressure, which is commonly found in tape, label, etc. Role in polymers. Magnesium oxide is commonly used as a filler, acid absorber, crosslinker or vulcanizing agent. Active magnesium oxide refers to its highly reactive form, with a large surface area, fine particles, and easy to react with other components.
In butyl adhesives, magnesium oxide acts as an acid receptor. Butyl rubber may decompose during processing or storage to produce acidic substances, which will affect the stability and performance of the adhesive. As an alkaline substance, magnesium oxide can neutralize these acids, prevent premature crosslinking or degradation, and prolong shelf life.
In addition, pressure sensitive adhesives require appropriate viscosity, cohesion and peeling forces. Magnesium oxide acts as a crosslinking agent or a vulcanization accelerator. During the vulcanization process, magnesium oxide works synergistically with vulcanizing agents (such as sulfur or peroxides) to promote cross-linking reactions, enhance the cohesive strength and heat resistance of the colloids, while maintaining a certain degree of elasticity, which is the performance of pressure-sensitive adhesives Very important.
In addition, magnesium oxide as a filler can adjust the rheological properties of the adhesive, such as viscosity, affecting the coating process and the thickness of the final product. It may also affect the mechanical properties of the adhesive, such as tensile strength and elastic modulus, thereby affecting pressure-sensitive properties. There are other effects, such as improving aging resistance, because magnesium oxide can absorb UV or heat and delay degradation. Or as a thixotropic agent, it prevents the colloid from flowing during storage and is easy to coat when used.
It should be noted that active magnesium oxide has high activity and functions more effectively than ordinary magnesium oxide, such as faster neutralization of acidic substances or more effective cross-linking promotion. The dosage may also need to be controlled. Too much may lead to excessive hardness of the colloid and affect pressure sensitivity; too little will cause insufficient effect.