Epoxy resin, phenol resin and unsaturated polyester resin are called three general-purpose thermosetting resins. They are varieties with large dosage and wide application in thermosetting resins. Epoxy resins contain unique epoxy groups, as well as active groups and polar groups such as light groups and ether bonds, and thus have many excellent properties. Compared with other thermosetting resins, there are many types and grades of epoxy resins with different performances. There are more types of epoxy resin curing agents, plus a large number of accelerators, modifiers, additives, etc., can be a variety of combinations and combinations. Thereby, various epoxy curing systems and cured products with excellent properties and various characteristics can be obtained. It can almost adapt to and meet the requirements of different performance and process performance. This is unmatched by other thermosetting resins.
1. Performance characteristics of epoxy resin and its cured products
(1) High mechanical properties. Epoxy resin has strong cohesion and dense molecular structure, so its mechanical properties are higher than general-purpose thermosetting resins such as phenolic resin and unsaturated polyester.
(2) Excellent adhesion performance. The extremely active epoxy, hydroxyl, ether bond, amine bond, ester bond and other polar groups in the epoxy resin curing system give the epoxy cured product with extremely high adhesive strength. Coupled with its high cohesive strength and other mechanical properties, it has particularly strong adhesive properties and can be used as a structural adhesive.
(3) The curing shrinkage rate is small. Generally 1%～2%. It is one of the thermosetting resins with a small curing shrinkage rate (phenolic resin 8%-10%; unsaturated polyester resin 4%-6%; silicone resin 4%-8%). The linear expansion coefficient is also very small, generally 6×10-5/℃. Therefore, the size of the product is stable, the internal stress is small and it is not easy to crack.
(4) Good manufacturability. Epoxy resin basically does not produce low molecular volatiles, so it can be molded under low pressure or contact compression molding. The flexibility of formula design is great, and a formula suitable for various technological requirements can be designed.
(5) Good electrical performance. It is one of the varieties with good dielectric properties in thermosetting resin.
(6) Good stability. Epoxy resins without impurities such as alkalis and salts are not easily deteriorated. As long as it is stored properly (sealed, protected from moisture, not exposed to high temperatures), its storage period is 1 year. It can still be used if the inspection passes after the expiration date. The epoxy cured product has excellent chemical stability. Its corrosion resistance to alkali, acid, salt and other media is better than that of unsaturated polyester resin, phenolic resin and other thermosetting resins.
(7) The heat resistance of the epoxy cured product is generally 80 to 100°C. The heat-resistant varieties of epoxy resin can reach 200 ℃ or higher.
(8) Among the hot horizontal resins, the comprehensive performance of epoxy resin and its cured product is good. Jinan epoxy resin
2. Application characteristics of epoxy resin
(1) has great flexibility and diversity in formula design. According to different use performance and process performance requirements, we can design a good targeted formula. This is a major feature and advantage in epoxy resin applications. However, each good formula has a certain scope of application (conditions), and it is not suitable for use under any process conditions and any use conditions. In other words, there is no "" good formula. Different best formulas must be designed according to different conditions. The curing principles of epoxy resin curing systems with different formulations are not exactly the same, so the curing process of epoxy resin, that is, the curing process conditions, has a great influence on the structure and performance of epoxy cured products. The performance of the product obtained by the same formula under different curing process conditions will be very different. Therefore, making the right material formula design and process design correctly is the key to epoxy resin application technology, and also the technical secret. In order to be able to produce and develop the epoxy materials with the required performance, it is necessary to design the corresponding special formula and molding process conditions. Therefore, it is necessary to deeply understand and master the structure and performance of epoxy resin and its curing agent, modifier, etc., the reaction mechanism between them and the influence on the structure and performance of epoxy cured products. Only in this way can the material formulation design and process design be handy, use freely, obtain a good plan, and produce and develop epoxy materials and products with good performance and low cost.
(2) Different epoxy resin curing systems can be cured at low temperature, room temperature, middle temperature or high temperature, can be cured on a wet surface or even in water, can be cured quickly, but also slowly, so it adapts to the requirements of construction and manufacturing processes Very strong. Epoxy resin can be molded by low pressure or contact pressure molding, so it can reduce the requirements for molding equipment and molds, reduce investment and reduce costs.
(3) Among the three general-purpose thermosetting resins, the price of epoxy resin is relatively high, thus being affected to a certain extent in application. However, because of its excellent performance, it is mainly used in applications requiring high performance, especially in areas requiring high comprehensive performanc