Main performance indicators of epoxy resin,Glue manufacturers
1. Epoxy value: The amount of epoxy based substance contained in every 100 grams of epoxy resin.
2. Epoxy group content: The mass of epoxy groups contained in every 100 grams of epoxy resin.
3 Epoxy Equivalent: The mass of epoxy resin containing one epoxy group, multiplied by the reciprocal of the epoxy value multiplied by 100.
4. Viscosity: Viscosity is a necessary property for low molecular weight epoxy resins and an important indicator related to the adhesive usage process. Use Tu-4 viscometer (4mm aperture), Tu-1 viscometer, rotational viscometer, etc.
5 Softening point: It is an important performance indicator of epoxy resin and a necessary performance test for medium molecular weight.
6 volatile components: 100g resin contains low molecular impurities and volatile components.
7. Epoxy resin refers to a general term for compounds that contain two or more epoxy groups in their molecules and can form a three-dimensional cross-linked structure in the presence of appropriate chemical additives such as curing agents.
It is a thermosetting resin with good bonding performance, corrosion resistance, high electrical insulation performance, and mechanical strength. It has many excellent properties and has a good bonding effect on both metals and non metals, so epoxy resin is known as the “versatile adhesive”
The Development History of Epoxy Resin
In the late 19th and early 20th centuries, two significant discoveries opened the curtain on the invention of epoxy resin.
In 1891, Lindmann from Germany reacted hydroquinone with epichlorohydrin to produce a resin like product. In 1909, Russian chemist Prileschajew discovered that epoxy compounds could be generated by reacting benzyl peroxide with olefins. These two chemical reactions are still the main pathways in the synthesis of epoxy resins to this day.
In 1934, Schlack used amine compounds to polymerize compounds containing more than one epoxy group to obtain high molecular weight polymers, which were published as a German patent.
After 1938, P. in Switzerland Castan and S. from the United States O. Multiple patents published by Greenlee have revealed the synthesis of epoxy resin through the condensation reaction of bisphenol A and epichlorohydrin. The resin can be cured using organic polyamines or phthalic anhydride, and has excellent bonding properties.
Soon, Swiss company CIBA, American company Shell, and Dow Chemical
The company has started the industrial production and application development of epoxy resin.
In 1947, the adhesive brand Araldite from the Swiss company Ciba began to attract attention, and epoxy resin became famous as a universal adhesive.
6. In addition, Shell’s EPON epoxy resin was introduced to the market as a coating. In 1956, the United Carbon Company in the United States began selling cycloaliphatic epoxy resin. In 1959, Dow Chemical Company produced phenolic epoxy resin.
7. It has been widely applied in various fields since its development.
1. Characteristics and advantages of epoxy resin adhesive
Strong adhesive strength and high mechanical strength; Containing aliphatic hydroxyl, ether, and highly reactive epoxy groups
a. Can be formulated into solvent-free adhesive with low shrinkage during the curing process; The addition of curing agent is achieved through direct addition reaction, and the curing process produces no by-products or bubbles (shrinkage rate less than 2%, with 0.1% filler added)
b. Can be cured at room temperature or high temperature; The temperature range for use is wide- 60-150 ℃.
c. High cohesive strength
d. Low creep, so it maintains good shape and dimensional performance under long-term pressure after curing
e. Good electrical insulation performance and good blending performance
Characteristics and disadvantages of epoxy resin adhesive
1. The cured material of unmodified resin is brittle
2. Some epoxy resins, reactive diluents, and curing agents pose certain risks to individuals and are even suspected to be carcinogenic substances
3. The epoxy adhesive prepared usually has a short service life. Although some systems are latent curing agents, they still need to be stored at low temperatures
2. Composition of epoxy resin adhesive
a. It is mainly composed of two parts: epoxy resin and curing agent.
b. To improve certain performance, diluents, accelerators, coupling agents, fillers, etc. are also added.
3. Type of epoxy resin
There are various types of epoxy resins, which can be classified into the following categories based on their chemical structure and the bonding method of epoxy groups:
(1) Glycyrrhetinic ethers
(2) Glycidyl esters
(3) Glycidyl amine
(4) Aliphatic epoxy compounds
(5) Cycloaliphatic epoxy compounds
(6) Hybrid epoxy resin
According to the state of resin at room temperature:
2. Liquid epoxy resin: can be used as casting material, solvent-free adhesive, and coating.
Solid epoxy resin: A relatively high molecular weight pure epoxy resin, a thermoplastic solid oligomer. Can be used as solvent based coatings, powder coatings, and solid forming materials.
This article is excerpted from Baidu Wenku