Views:2 Author:Site Editor Publish Time: 2021-10-13 Origin:Site
The traditional method of hot melt gluing system is to mix high molecular weight polymers and low molecular weight gums to achieve the desired overall performance. At present, the biggest feature of the hot melt adhesive system is that the resin and polymer are based on petroleum raw materials.
At present, the most widely used hot melt adhesive system is the ethylene-vinyl acetate copolymer (EVA) hot melt adhesive machine, which accounts for about 80% of the total output of the hot melt adhesive system. In addition to EVA, PE, PP, Polyester, polypeptide, PU, styrene and butadiene or isoprene block copolymers, ethylene-butene block copolymers, epoxy resins and phenolic resins, etc. Can be used for hot melt glue machine. Some new materials, such as EEA, EAA, EMA, PPO, PB, etc. are also used in hot melt glue machines.
(1) Host polymer
The polymer is the most important part of the hot melt glue machine. Some polymers can be used as hot melt glue machines without adding any additives. The polymer gives the hot melt glue machine its bonding strength and cohesion.
(2) erection enhancer
Most hot melt gluing system contain erection enhancers. The dosage is about 30%~50%. Adding erection agent can reduce the melting temperature of the main polymer, control the curing speed, improve the wettability and initial tack, thereby improving the bonding performance. Such as petroleum resin, rosin, betting olefin resin, coumarone resin, etc. can be used as erection agents.
(3) Antioxidant and stabilizer
The purpose of adding antioxidants is to prevent thermal oxidation and thermal decomposition of the hot melt adhesive system in a high-temperature molten state, and to maintain the same performance. Commonly used are p-tert-butylphenol, sodium benzoate and so on.
The role of stabilizers is the same as antioxidants. For example, benzene-based compounds are more commonly used.
The filler can increase the cohesive strength of the glue cat agent and reduce the cost. At the same time, it can also prevent glue leakage and reduce shrinkage. Commonly used fillers for hot melt adhesive systems are talc, calcium carbonate, soil turning, iron dioxide, magnesium sulfate, carbon black and so on.
The purpose of adding wax to the hot melt glue machine is to lower the melting temperature, prevent self-adhesion, and improve the operating performance. Commonly used waxes are micro wax, paraffin wax, polyethylene wax and so on. A few hot melt glue machines such as polyester and polyphthalamide can improve performance without wax.
Plasticizers can improve the low temperature properties of the glue. The general dosage should not be too much.
1. Avoid operating the hot melt adhesive coating machine around volatile and explosive materials or gases. Flammable and explosive materials cannot be stored around the spraying equipment of the hot melt adhesive coating machine.
2. Do not operate and use the hot melt adhesive coating machine without proper protection devices, good insulators or good protection panels. When maintenance is required, only professionally trained personnel can disassemble the machine for maintenance.
3. Do not operate the hot melt adhesive coating machine in the surrounding environment where the temperature is lower than 0°C or the temperature is higher than 50°C.
4. Try to use it where there is no fast flowing air. Because when the hot-melt glue nozzle assembly is exposed to fast-circulating air, the rapid cooling will affect the hot-melt glue flow rate of the nozzle assembly, which is prone to wire drawing.
5. When adding hot melt glue, it should be added before at least one third of the hot melt glue in the melt pot to avoid adding glue when there is no hot melt glue in the hot melt pot, which will affect normal production.
6. The amount of replenishing glue shall not exceed 80% of the total volume of the hot melt glue pot.