The traditional method of hot melt adhesive is to mix high molecular weight polymer with low molecular weight resin to achieve the desired comprehensive properties. At present, one of the most important characteristics of hot melt adhesive is that the resins and polymers used are mostly based on petroleum raw materials.
At present, the most widely used hot-melt adhesive machine is ethylene ethylene vinyl acetate copolymer (EVA) hot melt adhesive machine, which accounts for about 80% of the total output of hot melt adhesive machine. In addition to EVA ', PE, PP, Polyester, polyphthalamines, PU, styrene and butadiene or isoprene block copolymers, the block copolymers of ethylene butene, epoxy resin and phenolic resin can also be used in hot melt adhesives. Some new materials, such as EEA, EAA, EMA, PPO and PB, are also applied in hot melt adhesive machine.
(1) main polymer
Polymer is the most important part of hot melt adhesive machine. Some polymers can be used as hot-melt adhesives without adding any auxiliaries. The polymer gives the hot melt adhesive machine the bonding strength and cohesion.
(2) cat agent
Most of the hot-melt adhesives contain a bob. Its dosage is about 30%~50. Adding sun Zeng can reduce the melting temperature of the main polymer, control the curing speed, improve the wettability and initial viscosity, thus improving the bonding performance. Such as petroleum resin, rosin, gamolene resin and ancient Malone resin can be used as cat raising agents.
(3) antioxidants and stabilizers
The purpose of adding antioxidant is to prevent the thermal oxidation and thermal decomposition of the hot-melt adhesive machine in high temperature melting state, and to maintain the same performance. Commonly used are tert Ding Jifen, benzoate and so on.
The role of stabilizers is similar to that of antioxidants, such as benzyl compounds.
(4) packing
Fillers can increase cohesive strength and reduce costs. At the same time, it can also prevent seeping and reduce shrinkage. Hot melt machine commonly used fillers, talc, calcium carbonate, earth, two iron oxide, Magnesium Sulfate, carbon black and so on.
(5) wax
The purpose of adding wax in hot melt adhesive machine is to reduce melting temperature and cat degree, prevent self adhesion and improve operation performance. Commonly used waxes are micro wax, paraffin, polyethylene wax, etc. A small number of hot melt adhesives such as polyacetic acid and polyphthalamine can be improved without wax.
(6) plasticizer
The plasticizer can improve the low temperature properties of the adhesive. The general dosage should not be too much.