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What are the differences between epoxy resin and unsaturated polyester resin?

May 28, 2020

Epoxy resins and unsaturated polyester resins are widely used in terms of use. When buying resins, many people will have doubts about the difference between epoxy resins and unsaturated polyester resins.

All polymer compounds containing epoxy groups in the molecular structure are collectively called epoxy resins. The cured epoxy resin has good physical and chemical properties, it has excellent adhesion strength to the surface of metal and non-metal materials, good dielectric properties, small set shrinkage, good dimensional stability of products, high hardness, It has good flexibility and is stable to alkali and most solvents, so it is widely used in various sectors of national defense and national economy for casting, impregnation, laminating materials, adhesives, coatings and other purposes.

"Polyester" is a class of polymer compounds containing ester bonds distinguished from resins such as "phenolic" and "epoxy". This polymer compound is produced by polycondensation reaction of dibasic acid and diol. When this polymer compound contains unsaturated double bond, it is called unsaturated polyester. This unsaturated polyester dissolves In monomers with polymerization ability (usually styrene)

When it becomes a viscous liquid, it is called unsaturated polyester resin (English name Unsaturated Polyester Resin referred to as UPR).

Therefore, the unsaturated polyester resin can be defined as a linear polymer compound containing unsaturated dibasic acid or glycol formed by polycondensation of a dibasic acid and a diol dissolved in a monomer (usually styrene) and Into a viscous liquid.

The difference is roughly:

1. Articles made with epoxy resin will have a better surface finish. If the mold surface finish is good and the shape is suitable, it can be cast and solidified, and good results can be obtained without grinding and polishing, but the casting part of unsaturated resin After solidification, it will shrink a little and the surface will be a bit sticky, but the inside has been solidified, so it must be polished and polished .

2. The advantage of unsaturated resin over epoxy resin is that it can defoam automatically ~~~ Because it contains defoamer ingredients, some small bubbles will disappear by itself. Although there are no bubbles in this product and there are factors that use a vacuum machine to remove bubbles, but I think that the resin also has some credit. If the epoxy resin is defoamed with a vacuum machine, it must be pumped all the time. . . . .

3. The anticorrosion performance is very different. The anticorrosion performance of epoxy resin is much stronger than that of unsaturated polyester resin. Epoxy resin is generally used in heavy anticorrosion engineering. The heavy anticorrosion of unsaturated polyester resin is generally modified ring Oxygen resins, in terms of process requirements, epoxy resins and unsaturated polyester resins generally have some differences in operation.

Differences in use:

Unsaturated polyester resin

Unsaturated resin smells not so good, please pay attention to ventilation when using it.

Epoxy resin

1. The concentration of epoxy resin is high, generally use a thinner to dilute before use,

2. Epoxy curing involves curing agents. There are many types of curing agents. Different curing agents are used, and the curing time is definitely different. Curing speed, if the difference is too large, it can be felt by the naked eye; if the curing time is long, the speed of curing can be detected by a viscometer, and the viscosity of curing fast increases particularly fast; there is the hardness after curing to evaluate the speed of curing . If you want to know the strength after curing, you can also make a standard spline, through mechanical testing to determine which material is better.

3. Epoxy resins contain double epoxy groups and require amine-based curing agents to participate in the curing reaction. The performance of the final product and the curing agent are very large, but in general the final cured products of epoxy resins are more cured than unsaturated polyester resins. The hardness and strength of the product are large. Of course, the price of epoxy resin is twice that of unsaturated polyester resin. Generally, artificial stone will choose unsaturated polyester resin, because the price is cheap. Epoxy resins are chosen for floors and anti-corrosion coatings because their performance is better and the anti-corrosion performance must be much stronger than unsaturated polyester resins.

Price difference

The price of epoxy resin as a whole is much higher than the price of unsaturated polyester resin. When buying resin, you should know what products you make, what are the requirements, and what kind of resin to do when you go to the information business. Products, such as high anti-corrosion requirements, or high product attention requirements, if hardness requirements are high, your own product is the best when you find it.