Hot melt adhesive is made up of tackifier, basic polymers, wax and antioxidants, plasticizers, fillers and other low molecular polymers. The following are introduced separately.
One, basic polymer low temperature hot melt adhesive
The basic polymer of hot melt adhesive is a thermoplastic resin, which is used to increase the bonding strength of the adhesive.
And cohesion, if the basic polymer of a single variety can not achieve a certain performance, it can be adaptable.
The same kinds of polymers are used in mixing. Usually in order to improve the comprehensive performance of hot melt adhesive or to reduce the heat melting
The cost of glue is often added to the quantitative isobutadiene rubber or random polypropylene.
A tackifier reduced melt viscosity heat Rong glue, increase the performance of the wettability and initial viscosity, due to the base
The melt viscosity of the polymer is generally quite high, and the wettability and initial viscosity are not up to the standard, so it is necessary.
Adding tackifier with good compatibility, melting temperature and thermal stability with the basic polymer,
In addition, the addition of the tackifier can also improve and increase the other properties of the hot melt adhesive.
The proportion of tackifier in hot melt adhesive is 20% to 150% of the basic polymer.
The main effect of wax can improve the fluidity and wettability of the liquid, and increase the adhesive strength and most of the adhesive.
The hot melt adhesive must be added to a certain amount of wax, but should pay attention to the appropriate amount and proportion of the amount, if the amount is excess, the glue is collected.
The shrinkage becomes larger and the adhesive strength decreases.
The commonly used wax is paraffin wax, microcrystalline paraffin, synthetic wax, and so on. The amount of wax is generally not super.
Over 30% of the weight of the basic polymer.
The above kinds of wax have different characteristics and are added to different types of hot melt adhesives respectively.
The common fillers are talcum powder, asbestos powder, carbon black, calcium carbonate, barium carbonate, magnesium carbonate, aluminum silicate and so on.
The effect of the filler increases the heat resistance of the hot melt adhesive and prolongs the shrinkage process of the hot melt adhesive, thus increasing the heat flux.
It can operate time and reduce cost.
The commonly used plasticizers are butyl phthalate, phthalic acid, two formic acid, two symplectic and so on.
Its role is to accelerate the melting speed, lower melt viscosity, improve the wetting of glued materials
To improve the flexibility and cold resistance of hot melt adhesive. But if the plasticizer adds excess, it will reverse it.
As a result, only a small amount or no plasticizer is added in the general hot melt adhesive.
The effect is to prevent hot melt adhesive from oxidation and thermal decomposition at high temperature for a long time.