Epoxy
Epoxy Overview
Epoxy resins are generally refers to molecules containing two or more epoxy group of organic polymers, barring a few exceptions, their relative molecular weight is not high. The molecular structure of epoxy resin is based on the molecular chain containing active epoxy group for its features, the epoxy group can be located at the end of molecular chain, in the middle, or into a cyclic structure. As the molecular structure containing active epoxy groups, so that they can place a variety of types of curing agents to form insoluble cross-linking reaction, non-melting with a three-network structure of the polymer.
Where the molecular structure of the polymer containing epoxy group collectively referred to as epoxy resin. Cured epoxy resin has excellent physical and chemical properties, its surface metal and nonmetal materials have excellent adhesive strength, good dielectric properties, variable setting shrinkage is small, product size, good stability, high hardness, flexibility of good stability of the alkali and most of the solvents, which are widely used in national defense, national economic departments for pouring, dipping, laminating materials, adhesives, paints and so on.
In China since 1958 conducted a study of epoxy resin and to speed quickly put into industrial production, has been booming throughout the country, in addition to producing common bisphenol A-epichlorohydrin epoxy resin, the yet the production of new types of epoxy resin, in order to meet national defense construction and national economic sectors need hair.
Preparation of epoxy resin has the following several types:
1, the active hydride reaction with epichlorohydrin;
2, hydrogen peroxide or a peracid (eg peracetic acid) to double bond liquid-phase oxidation;
3, double bond compounds, the air oxidation;
4, other.
Because of its performance is not perfect, while the target application of epoxy resin is not all a thousand times, according to the use of different targets, the performance of epoxy resin have also been asked, for example, some request a low-temperature drying, and some excellent insulation performance requirements. And therefore should be targeted to the epoxy resin to be modified, the modified method has the following categories:
1, select the curing agent;
2, add reactive diluents;
3, add the filler;
4, add other kinds of thermosetting or thermoplastic resin;
5, modified epoxy resin itself.
