The glycidyl ether epoxy resin is obtained by polycondensation of an active hydrogen-containing phenol or alcohol with epichlorohydrin.
(1) Diphenol-based propane type epoxy resin The diphenol-based propane type epoxy resin is obtained by polycondensation of diphenol-based propane and epichlorohydrin.
Industrial diphenolic propane type epoxy resins are actually mixtures of molecules containing different degrees of polymerization. Most of these molecules are linear structures containing two epoxy end groups. A few molecules may be branched, and a very few molecules terminate in a group that is a chlorohydrin group rather than an epoxy group. Therefore, the epoxy group content and the chlorine content of the epoxy resin have a great influence on the curing of the resin and the properties of the cured product. The industrial control indicators for the resin are as follows:
1 epoxy value. Epoxy value is the most important indicator to identify the properties of epoxy resin. Industrial epoxy resin type is distinguished by epoxy value. The epoxy value refers to the amount of the epoxy group-containing substance per 100 g of the resin. Multiplying the reciprocal of the epoxy value by 100 is called the epoxy equivalent. The meaning of the epoxy equivalent is the number of grams of epoxy resin containing 1 mole of epoxy group.
2 inorganic chlorine content. The chloride ion in the resin can cooperate with the amine curing agent to affect the curing of the resin, and also affect the electrical properties of the cured resin. Therefore, the chlorine content is also an important indicator of the epoxy resin.
3 organic chlorine content. The content of organic chlorine in the resin indicates the content of the part of the chlorohydrin group in the molecule which has not been subjected to the ring closure reaction, and its content should be reduced as much as possible, otherwise it will affect the curing of the resin and the properties of the cured product.
4 volatiles.
5 viscosity or softening point.
(2) Phenolic polyepoxy phenolic polyepoxy resin includes phenol formaldehyde type and o-cresol formaldehyde type epoxy resin, which contains more than two in-line molecules compared with diphenol-based propane type epoxy resin. The epoxy group has a high crosslink density of the product after curing, and has excellent thermal stability, mechanical properties, electrical insulation, water resistance and corrosion resistance. They are formed by polycondensation of a novolac resin and epichlorohydrin.
(3) Other polyhydric phenolic glycidyl ether type epoxy resins The practical representatives of such resins are: resorcinol type epoxy resin, resorcinol-formaldehyde type epoxy resin, tetraphenol based Alkyl epoxy resin and trishydroxyphenylmethane epoxy resin. These polyfunctional glycidyl ether resins have high heat distortion temperature and rigidity after curing.
Or blended with general-purpose E-type resin for use as a base material for high-performance composite materials (ACM), printed wiring boards, etc.
(4) aliphatic polyol glycidyl ether type epoxy resin aliphatic polyol glycidyl ether molecule contains two or more epoxy groups, most of which are low in viscosity; most are long chains Linear molecules are therefore flexible.
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