Hot melt adhesive is a kind of solid fusible polymer without solvent and without water content. At room temperature for solid, heated to a certain temperature after melting into a certain viscous liquid. After melting hot melt adhesive, light brown or white. Hot-melt adhesive is composed of basic resin, viscosifier, viscosity regulator and antioxidant.
1, basic resin, hot melt adhesive basic resin is ethylene and vinyl acetate copolymerization under high temperature and high pressure, that is, EVA resin. This resin is the main ingredient in the production of hot melt adhesive, accounting for more than 50% of the number of ingredients. The proportion and quality of basic resin determine the basic properties of hot melt adhesive, such as adhesive bonding ability, melting temperature and the selection of additives. Hot melt adhesive should choose the appropriate proportion of ethylene and vinyl acetate, with a certain softness, elasticity, adhesion, deformation of small varieties used.
2, viscosifier is one of the main additives of hot melt adhesive, if only the basic resin melting at a certain temperature has the bonding force, when the temperature drops, it is difficult to lubricate and penetrate the adhesive, lose the bonding ability, unable to achieve the bonding effect; Adding viscosifier can improve the fluidity of colloid and the wettability of the adhesive, improve the bond performance, to achieve the required bond strength.
3, viscosity regulator is also one of the main additives of hot melt adhesive. Its role is to increase the fluidity of colloid, adjust the solidification speed, in order to achieve the purpose of fast bonding firm, otherwise the hot melt adhesive is too big, unable or not easy to flow, difficult to penetrate into the adhesive, it can not bond firmly. Adding the viscosity regulator with low softening point can achieve the purpose of good penetration and firm adhesion when bonding.
4. Adding an appropriate amount of antioxidant is to prevent premature aging of hot melt adhesive. Because the colloid will be oxidized and decomposed at high temperature when melting, adding antioxidant can ensure that the bond performance does not change under high temperature conditions.