Classification of Epoxy Resin Structural Adhesives

Epoxy structural adhesives are the most important and most sought after products in structural adhesives, and they are becoming more and more known as the importance of building safety requirements increase. After the “Shenzhou VI” was launched, domestic epoxy resin structural adhesives used on spacecraft were also highlighted at home and abroad. Bluestar New Materials for this material Wuxi Resin Factory recently received a large number of telephone calls in this area.

The expert said that the important parts of the "Shenzhou VI" spacecraft, such as cockpits, floors, antennas, solar cells, and instrument cabins, must be tightly joined together after undergoing enormous tests of high and low temperature changes and strong impact forces. To achieve this requirement requires the use of structural adhesives with excellent properties. Epoxy adhesives are recognized as the best and dominant structural adhesives. Epoxy resin itself is an adhesive. In the application process, it reacts with the epoxy curing agent according to the process and application requirements to complete the curing and achieve the adhesive function. Bluestar New Materials Wuxi Resin Factory is a special material provider for China's previous space launches. It provides special epoxy resin with excellent performance. It tightly binds the structures of various parts of the spacecraft and plays an irreplaceable role. The formulation, test environment, and base material varieties of space epoxy resin structural adhesives are all confidential.

He said that the epoxy structural adhesive refers to a type of adhesive that accepts force structural components. In the connection of the structural parts, the glue connection has greater advantages than the traditional riveting, screwing and welding. The use of synthetic adhesives to receive force structures began in the 1940s. At that time, due to the needs of modern industry, especially the development of aviation and other military industries, the synthetic polymer industry was in an emerging period, so the structural adhesives developed rapidly. Epoxy structural adhesives are one of the most important varieties.

At present, there is no universal consensus on the definition, classification and evaluation criteria of structural adhesives at home and abroad. The opinions of various industries are also not the same. American Aerospace Structural Adhesive Standard MMM-A-132 According to the requirements of different Mach number flight speed for heat resistance, structural adhesives are divided into four types, and shear, fatigue, creep, aging, T-type peeling, etc. Strength specifications have been specified. Type I corresponds to a flight speed of 1 Mach or less and specifies the room temperature and 82°C strength indicators; Type II corresponds to a Mach 1 to 2 number and specifies the room temperature and 149°C strength indicators; Type III and Type IV correspond to 2 Mach number up to 3 Mach or so, the room temperature, 149 °C and 260 °C strength indicators. The latter three types are high-temperature structural adhesives for supersonic aircraft.

According to the strength of the different type I is divided into three levels, the following provisions: one for the main force structure of the glue, for structural adhesives; two for the secondary force structure of the glue, the standard structural adhesive; There is no requirement for peel strength and should be a non-structural adhesive. There is no national standard for the definition and classification of structural adhesives in China. According to the force conditions and bonding strength of bonded objects, structural adhesives are divided into high-strength, high-toughness, medium-strength, and medium-toughness: main force structural adhesives. The steel-steel shear strength ≥ 25MPa, tensile strength ≥ 33MPa, uneven tear strength ≥ 40kN / m. The shear strength of the secondary force structural adhesive is 17 to 25 Mpa, and the uneven tear strength is 20 to 50 kN/m.

According to the curing temperature, the epoxy structural adhesive can be divided into four categories: high temperature curing, medium temperature curing, room temperature curing and low temperature curing: the temperature, toughness, heat resistance and the like of the high temperature curing epoxy structural adhesive are all high, and are mainly used in the main force structure. Adhesive bonding; intermediate temperature curing epoxy structural adhesives are mainly developed to meet the needs of the aircraft industry. As aluminum alloys begin to exhibit grain boundary corrosion tendencies above 120°C and increase with increasing temperature, grain boundary corrosion occurs. The strength and toughness of the green alloy will be reduced. Therefore, the curing conditions of the adhesive for bonding the aluminum alloy are not required to exceed 130° C./4 h. The room-temperature curing epoxy structural adhesive is more widely used. The application in the field of civil engineering is even more important. It is one of the main varieties of building structural adhesives. Low-temperature curing epoxy adhesives have been developed in recent years to meet the needs of low-temperature construction in winter. A new class of rubbers can be developed at 0°C. It can even be applied and cured below -10°C.

According to the heat resistance, structural adhesives can be divided into three types: general type (≤80°C), high-temperature type (≥150°C) and medium-temperature type (between the former and the former).
With regard to the characteristics of epoxy structural adhesives, the expert from the Wuxi Resin Plant of Bluestar New Materials Co., Ltd. introduced that the main strengths are: high strength and toughness, good overall performance, and high reliability of bonding. The formula design is flexible, with great selectivity, and can adapt to various usage requirements. Easy to use process. Epoxy structural adhesives are used extensively in the aviation and aerospace industries for the manufacture of honeycomb sandwich structures, all-glued sheet metal structures, composite metal structures (such as steel-aluminum, aluminum-magnesium, steel-bronze, etc.) and metal-polymer composites. The composite structure. Used as wing skin, fuselage wallboard, artificial satellite structure, rocket engine shell and so on. In the shipbuilding industry, it is used to glue the propeller to the boring axis and to glue the crankshaft. In the machinery manufacturing industry, the precision and strength of the set inserts for the screw thread of heavy-duty machine tools are greater than that of the whole screw. In recent years, the application of epoxy structural adhesive has been rapidly developed in civil construction. Widely used in housing, bridges, tunnels, dams and other reinforcement, anchoring, infusion bonding, repair and other aspects.