Synthetic method and three characteristics of epoxy resin

1, liquid BPA
epoxy resin synthesis method is summarized in two ways: one-step and two-step method.
method can be divided into one-time alkali addition and secondary alkali-added method. The two-step method can be divided into intermittent and continuous methods

. The one-step process is the adjuvantation of biphenol A and epoxy chloropropane under NaOH action, i.e. open-loop and closed-loop reactions under the same reaction conditions. At present, the largest domestic production of E-44 epoxy resin is the use of one-step process synthesis.
two-step process is biphenol A and epoxy chloropropane under the action of catalysts (e.g. gymonium salts), the first step through the addition reaction to produce diphenol propane chlorol ether intermediates, the second step in the presence of NaOH closed-loop reaction to produce epoxy resin. The advantages of the two-step method are: short reaction time, stable operation, small temperature fluctuations, easy to control, short alkali-added time, can avoid a large amount of hydrolysing of epoxy chloropropane, good and stable product quality, high yield. Domestic E-51, E-54 epoxy resin is the use of two-step process synthesis.
2, solid BPA
epoxy resin synthesis methods can also be broadly divided into two methods: one-step and two-step. The one-step method can be divided into washing method, solvent extraction method and solvent method. The two-step method can also be divided into ontogeneization legal and catalytic polyploration legal.
step method (known abroad as the Taffy method) process is to shrink bisphenol A and epoxy chloropropane under NaOH action, used in the manufacture of medium relative molecular mass solid epoxy resin. Such as domestic production of E-20, E-14, E-12.
two-step method (foreign called advancment method) process is to low relative molecular mass liquid E-type epoxy resin and BPA heating dissolved, at high temperature or catalyst action to increase the reaction, continuously expand the chain, and finally form a high relative molecular mass solid epoxy resin, such as E-10, E-06, E-03, etc. are synthesized by this method.
the advantages and disadvantages of step 3, one-step method and two-step method
when synthesized by step method, the reaction is carried out in a emulsion in water. Reprocessing is difficult when preparing high-relative molecular mass resins. The resin is distributed widely relative to molecular mass and has high organchlorine content. It is not easy to obtain products with high epoxy value and high softening point to meet the requirements of powder coating.
And two-step synthesis, the reaction is ermosynthetic, the chain growth reaction is relatively stable, so the resin is made relative to the molecular mass distribution is narrow, the organic chlorine content is low, epoxy value and softening point can be ratio and reaction temperature to control and adjust. With simple process, easy to operate, less equipment, short working hours, no waste, a reaction can be, product quality easy to control and adjust and other advantages, so increasingly attention.
three characteristics of the application of epoxy resin
1, with great flexibility and diversity in formulation design. According to different use performance and process performance requirements, the design of a highly targeted best formula. This is a major feature and advantage of epoxy applications. However, each best formula has a certain scope of application (conditions), not in any process conditions and arbitrary conditions of use should be used. That means there is no "one-of-a-world" best formula. Different optimal formulations must be designed according to different conditions.
Because the curing principle of the epoxy curing system of different formulations is not exactly the same, the curing process of epoxy resin, i.e. the curing process conditions have a great impact on the structure and performance of epoxy curing. The performance of the same formula under different curing process conditions can vary greatly. Therefore, making the best material formulation and process design correctly is the key to epoxy application technology, but also the technical secret.
it is necessary to understand and master the structure and properties of epoxy resins and their curing agents, modifiers, etc., the reactions between them, and the effects on the structure and properties of epoxy curings. In this way, in the material formulation design and process design is handy, the use of free, to obtain the best solution, the production and development of the best performance, the lowest cost epoxy materials and products.
2, different epoxy curing system can be at low temperature, room temperature, medium temperature or high temperature curing, can cure on wet surfaces and even in water, can quickly cure, can also slowly cure, so it is very adaptable to construction and manufacturing process requirements. Epoxy resins can be molded at low pressure or in contact with pressure molding, thus reducing the requirements for molding equipment and molds, reducing investment and reducing costs.
3, in the three general-purpose thermo-solid resins, the price of epoxy resin is high, so that the application is affected to a certain point. However, because of its excellent performance, it is mainly used in applications where performance requirements are high, especially in areas where comprehensive performance is high.