Hydroxypropyl Methylcellulose Synthesis Adhesive

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Company News

Release time:

2019-06-18


Adhesives are generally divided into three types: organic adhesives, inorganic adhesives, and metal powder adhesives. Common organic adhesives mainly include: epoxy adhesives and organic silicone adhesives. The main performance difference between them and inorganic adhesives is temperature resistance. The maximum temperature resistance of organic adhesives is usually between 100-250 degrees, and generally does not exceed 400 degrees. The temperature resistance of inorganic adhesives is usually between 600 to 1750 degrees Celsius. Organic adhesives can be soft or rigid, while inorganic adhesives are usually rigid and hard. Common metal powder adhesives mainly include some low melting point metal powders, and their temperature resistance depends on the melting point of the metal powder.
Organic adhesives mainly include: epoxy adhesives, organic silicone adhesives, and acrylic adhesives.
Inorganic adhesives mainly include silicate-based adhesives, phosphate-based adhesives, and aluminum silicate, etc.
Metal powder adhesives mainly include: pure aluminum powder, etc.
Among them, organic adhesives are the most widely used, and epoxy adhesives in organic adhesives are closely related to our lives!
 
Epoxy adhesives
Generally, in the absence of oxygen, the thermal decomposition temperature of epoxy resin is above 300℃. When used in air, thermal oxidative decomposition usually occurs at 180 to 200℃. When aging at this temperature for a period of time, the strength is even lower. Most alicyclic epoxy resins are relatively stable below 200℃, but thermal oxidative damage is more severe than that of bisphenol A epoxy resins above 200℃. This may be because alicyclic structures do not have aromatic ring stability. The thermal oxidative stability of bisphenol A epoxy resins cured with aromatic amines is not as good as that of alicyclic type A epoxy resins cured with alicyclic or aromatic anhydrides. This is because there are more hydroxyl groups in the amine-cured epoxy structure. Dehydration reactions are easily triggered at lower temperatures. In addition, the N atom on the amine is also more susceptible to thermal oxidative damage. However, hydroxyl groups are rarely formed in anhydride-cured products. However, at temperatures above 290℃, the molecular chains of both types of curing agents will begin to break. From the above, it can be seen that bisphenol A type epoxy resins have poor high-temperature resistance. The cured products of anhydrides have higher temperature resistance than those cured with aromatic amines.

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