The nature and use of 10 kinds of special adhesives

Reading Volume：【 143 】

Time：【 2023-07-21 】

Adhesive is also known as adhesive or bonding agent, referred to as glue. In addition to welding, nail now, mirror, embedded, where two things can be connected together by bonding, and can meet the physical and chemical properties of the substance called adhesive or adhesive.

Specialty adhesive refers to a special performance, for special occasions, bonding special materials, can meet the special requirements of a class of adhesives. It mainly includes the following types of high-temperature adhesive, ultra-low temperature adhesive; sealant; photosensitive adhesive; medical book adhesive; conductive, magnetic, thermal conductive adhesive; strain adhesive, underwater adhesive; alkali adhesive, spot welding adhesive, vacuum adhesive and so on.

01High temperature adhesive
High-temperature adhesive refers to the use of 200-500 ℃ or higher temperatures without losing the original bonding properties of a class of adhesives. This kind of adhesive is mainly containing silicon, boron polymer, containing aromatic heterocyclic high temperature polymers and inorganic adhesives.

Polyimide adhesive can be in 370-390 ℃ long-term work, short-term use of the temperature can exceed 500 ℃, the current international use is mainly made of film, this kind of adhesive high-temperature strength, electro-thermal properties are stable, radiation resistance, low temperature resistance is excellent.

Polybenzimidazole adhesive can be used for a long time in 250-370 ℃, short-term use of quality can be more than 500 ℃, high bonding strength, usually formulated as a solution adhesive use.

Polybenzothiazole adhesives can be used at temperatures higher than 500 ℃, high-temperature strength, can be used as high-temperature structural adhesive, with good water resistance and alkali resistance.

Polyarylsulfone adhesives, there are many types, can be used in 240-300 ℃, with water resistance, oil resistance, electrical insulation and chemical stability.

Polyphenylene sulfide adhesive, there are many types, polyphenylene sulfide adhesive can be used for a long time at 350 ℃, generally can be used at 350-400 ℃, with water resistance, oil resistance, electrical insulation and chemical stability.

02

Low temperature adhesive

Ultra-low temperature adhesive is able to be used in ultra-low temperature (such as liquid helium -269 ℃, liquid nitrogen -196 ℃, liquid oxygen -196 ℃) environment and have sufficient strength of the kind of adhesive. Ultra-low temperature is an important problem that must be solved in the high thrust advanced delivery system with liquid hydrogen and liquid oxygen as propellants. Involving ultra-low temperature structure and many parts, in addition to the aforementioned structure directly in the ultra-low temperature work of liquid hydrogen, liquid oxygen tank bottom, liquid hydrogen, liquid oxygen tank body and adiabatic layer and adiabatic layer and the outer surface of the sealing layer of the adhesive between the delivery of liquid hydrogen, liquid oxygen pipeline outside of the adiabatic layer of the adhesive, as well as other ultra-low-temperature structure is connected to the adhesion of parts and components of the adhesive, these adhesive and sealing adhesive used, not only need to have a room temperature and These adhesives used for bonding and sealing, not only need to have room temperature and ultra-low temperature of sufficient bonding strength, but also must have and different materials to be adhered to match the coefficient of thermal expansion between the good. It is not only used for missiles, aircraft, but also used to contain liquid oxygen Dewar's bottle and cold knife (drinking therapy) liquid nitrogen cold source equipment and other aspects of the bonding.

Ultra-low temperature adhesive Bu often with polyurethane or polyurethane modified with epoxy resin, or polyurethane and nylon modified epoxy resin, etc. as the main body of the formulation.

03Sealing Adhesive
The main components of the sealant are synthetic rubber and resin, plus fillers and additives, solvent-containing or solvent-free viscous liquid. Coated in the joint surface, because it can fill the surface unevenness, dry for a certain period of time to make the formation of a continuous viscoelastic film, so as to play a pressure-resistant, sealing effect.

According to the classification of chemical composition, can be divided into

1. resin such as epoxy resin, polyurethane, etc. 2. rubber such as NBR.

2. rubber, such as nitrile rubber, polysulfide rubber.

3. mixed category such as polysulfide rubber and phenolic resin, neoprene rubber and alkyd resin.

4. natural polymers, such as gum, gum arabic, etc.

04 optical adhesive
Optical adhesive means that it is very sensitive to light, it is also known as light-curing adhesive, photosensitive adhesive or photosensitive resist, by the resin monomer or prepolymer plus photosensitizer and other components, in the irradiation of ultraviolet light, photosensitizer decomposition of free radicals in a few minutes can be caused by the polymerization of monomers and curing, but not before the addition of photosensitizers, photosensitive adhesive is very stable, can be stored for a long time. Once the photosensitizer is added, it should be placed in a darker place, or into a brown bottle, even so, the time will not be too long.

Photosensitive adhesive for light-transparent parts of the adhesive assembly, or light-transparent materials and metal, plastic bonding, can be used for plexiglass splicing interface, the plexiglass monomer made of pre-polymer, add photosensitizer, irrigation in the interface, after illumination, ultraviolet light excitation polymerization, 5-6h can be cured, the interface will be put together, in the electronics industry is widely used in the photolithography of the miniature circuits, which plays an important role in the production of microcircuits.

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