EVA hot melt adhesive is a kind of solid fusible polymer that does not need solvent and does not contain moisture. It is a solid at room temperature. It melts to a certain temperature and turns into a viscous liquid. The melted EVA hot melt adhesive is light brown or white. EVA hot melt adhesives consist of basic resins, tackifiers, viscosity modifiers, and antioxidants.
Basic resin
The basic resin of EVA hot melt adhesive is ethylene and vinyl acetate copolymerized under high temperature and high pressure, namely EVA resin. This resin is the main component of the hot melt adhesive, accounting for more than 50% of its ingredients. The ratio and quality of the basic resin determine the basic properties of the hot melt, such as the binding ability of the glue, the melting temperature and the choice of additives. Therefore, the EVA hot melt adhesive used for binding the binding paper should be selected from a variety of products that have an appropriate ratio of ethylene to vinyl acetate and have a certain degree of flexibility, elasticity, adhesion, and deformation.
Tackifier
Tackifiers are one of the main additives of EVA hot melt adhesives. When the resin melts, it has a cohesive force at a certain temperature. When the temperature drops, it becomes difficult to wet and penetrate the paper, loses the ability to bond, and cannot achieve a bonding effect; the viscosity can be increased by adding a tackifier. And the wettability to the adherends improves the adhesive properties and achieves the required bond strength.
Viscosity modifier
Viscosity modifiers are also one of the main additives for hot melt adhesives. Its role is to increase the fluidity of the colloid and adjust the solidification speed so as to achieve the purpose of fast bonding firmly. Otherwise, the viscosity of the hot melt adhesive is too large, unable or difficult to flow, and it is difficult to penetrate into the signature, and it cannot be bonded. firm. Adding a viscosity modifier with a low softening point can achieve the purpose of good penetration and stickiness when bonding.
Antioxidants
The proper amount of antioxidant is added to prevent premature aging of the EVA hot melt adhesive. Because the colloid will oxidize and decompose when the temperature is high at the time of melting, adding the antioxidant can ensure that the adhesive property does not change under the high temperature condition.
In addition to the above raw materials, it is also possible to add some cold-resistance agents suitable for cold-air temperature or heat-resistant agents suitable for tropical temperatures based on the temperature and regional differences.
