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Introduction and application of epoxy resin

May 29, 2020

Epoxy resin refers to an organic compound containing two or more epoxy groups in the molecule. Except for individual, their relative molecular mass is not high. The molecular structure of epoxy resins is characterized by the presence of active epoxy groups in the molecular chain. The epoxy groups can be located at the end, middle or in a ring structure of the molecular chain. Because the molecular structure contains active epoxy groups, they can crosslink with various types of curing agents to form an insoluble polymer with a three-dimensional network structure. 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 deformation shrinkage, good dimensional stability of products, high hardness and flexibility Good performance, stable to alkali and most solvents, so it is widely used in various departments of national defense and national economy, for casting, dipping, laminating materials, adhesives, coatings and other purposes.

1. Domestic research

The development of epoxy resin has experienced a long period of time. As early as 1891, Lindmann of Germany used hydroquinone to react with epichlorohydrin, polycondensed into resin and cured with acid anhydride, but its use value was not revealed. In 1930, Pierre Castan of Switzerland and S.O. Greenlee of the United States conducted further research and cured the above resins with organic polyamines, which showed high bonding strength, so that people found its application value. In 1938, Swiss P. Castam applied for a patent. In 1947, Devoe-Raynolds of the United States opened up the technical history of epichlorohydrin-bisphenol A resin, and epoxy resin began industrial development. Soon CIBA in Switzerland, Shell and Dow in the United States began industrial production and application development of epoxy resins.

China has conducted research on epoxy resins since 1958 and has put it into industrial production at a rapid rate. It has been developing vigorously throughout the country. In addition to the production of ordinary bisphenol A-epichlorohydrin epoxy resins, It also produces various types of new epoxy resins to meet the urgent needs of national defense construction and various sectors of the national economy.

2. Classification of epoxy resin

Epoxy resins are roughly divided into five categories: glycidyl ether epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, linear aliphatic epoxy resins, and alicyclic epoxy resins .

3. The advantages of epoxy resin and its cured products:

1) High bonding strength, because the system contains active epoxy groups, hydroxyl groups, ether bonds, amine bonds, ester bonds and other polar groups, it has high adhesion to metals, ceramics, glass, concrete, wood, etc.接 Strength.

2) The curing shrinkage rate is small, phenolic resin glue 8-10%, silicone resin glue 6-8%, polyester resin glue 4-8%, epoxy resin glue 1-3%, modified epoxy resin The glue shrinkage can be reduced to 0.1-0.3%.

3) Excellent chemical stability, acid, alkali, salt, oil resistance impregnation, used as anti-corrosion primer, used as lining of oil tank inner wall of oil tanker and aircraft.

4) Excellent electrical insulation, the breakdown voltage of epoxy resin can be greater than 35kv / mm.

4. Application fields of epoxy resin

1) Coating industry: epoxy resin has the largest demand in the coating industry, and currently widely used are water-based coatings, powder coatings and high-solids coatings. It can be widely used in industries such as pipeline containers, automobiles, ships, aerospace, electronics, toys, crafts, etc.

2) Electronic appliance industry: epoxy resin adhesive can be used for electrical insulation materials, such as rectifier, transformer sealing and pouring; sealing and protection of electronic components; insulation treatment and bonding of electromechanical products; sealing and bonding of storage batteries; capacitors, resistors, The surface of the inductor is covered.

3) Hardware accessories, handicrafts, sports goods industry: can be used on signs, accessories, trademarks, hardware, rackets, fishing tackle, sporting goods, handicrafts and other products.

4) Optoelectronic industry: It can be used for packaging, pouring and bonding of light-emitting diode (LED), digital tube, pixel tube, electronic display screen, LED lighting and other products.

5) Construction industry: It is also widely used in industries such as roads, bridges, floors, steel structures, buildings, wall coatings, dams, engineering construction, and repair of cultural relics.

6) Adhesives, sealants and composite materials: such as the bonding of various materials such as wind turbine blades, handicrafts, ceramics, glass, etc., the composite of carbon fiber sheets, the sealing of microelectronic materials, etc.

5. Production of epoxy resin

1.1 Regional distribution of epoxy resin production in the world

The production of epoxy resin is mainly concentrated in the three regions of China, Japan and Europe, and the others include South Korea, the United States, Taiwan, Thailand, South Africa and Venezuela. The production capacity of mainland China accounts for about 60% of the world's total production capacity.

1.2 Monopoly pattern of epoxy resin production in the world

The world's epoxy resin production is mainly monopolized by the three giants Shell, Dow and Ciba. In addition, Japan's Dongdu Chemical, Dainippon Ink, Japanese epoxy resin manufacturing company, South Korea's Guodu Chemical (joint venture with Japan's Dongdu Chemical) Several of them also occupy a remarkable place in the world epoxy industry with their advanced production technology.

1.3 Situation of domestic epoxy manufacturers

There are more than one hundred epoxy resin manufacturers in China, but most of them are small except Yueyang and Wuxi. At present, most domestic epoxy resin factories are small in scale, with a single brand variety, backward equipment, and low resin quality. In the case of Shell, Dow, Ciba, and several companies in Japan are stepping up to penetrate the Chinese epoxy consumer market, domestic manufacturers Facing extremely severe challenges.

Since 2010, the demand for major epoxy resin application markets worldwide has recovered. The data from the "2014-2018 Production and Sales Demand and Investment Forecast Analysis Report for China's Epoxy Resin Industry" show that Oxygen resin demand is growing at a rate of 3.2% and 2.8% respectively, and will continue to grow from 2% to 3% from 2014 to 2018. Benefiting from the rapid development of the Chinese market, global epoxy resin demand will be around 4.5% Growth rate.

Although the global epoxy resin industry has entered a mature period, according to the forecast of the Prospective Industry Research Institute, the compound growth rate of the global epoxy resin industry will be about 4% -5% in the next 5 years. However, from the perspective of the domestic market, the compound annual growth rate of apparent domestic epoxy resin consumption in 2002-2013 was above 10%, much higher than the average growth rate of the global epoxy resin industry. It is expected that the domestic epoxy resin industry will continue to grow steadily in the future. On the one hand, the global industrial transfer has caused downstream industries such as electronics and shipping to be produced in China, which has driven the demand for epoxy resins. On the other hand, the quality of products produced by domestic enterprises With continuous improvement, it gradually has a comparative advantage compared with foreign companies.

According to the forecast of the Prospective Industry Research Institute, while China's GDP continues to maintain a high growth trend, the compound annual growth rate of domestic epoxy resin demand will reach about 10% in the next few years, and the total consumption in 2015 will reach 1.5 million tons, accounting for To about 60% of the global epoxy resin consumer market.