1.1 Definition and History
Anaerobic adhesives refer to a series of anaerobic cure compositions that can act as bonding, fixing, and sealing. The following are referred to as anaerobic adhesives, anaerobes, also known as anaerobic adhesives, anaerobic adhesives, and thread adhesives. Mechanical glue. It does not solidify when in contact with oxygen or air, and quickly polymerizes to become a cross-linked solid polymer once air is shut off. By "anaerobic" is meant that the glue does not require oxygen when used.
The development of foreign anaerobic adhesives began in the 1940s. In 1953, RE Burnett and VK Krieble of the United States discovered the anaerobic solidification properties of acrylates when they were used to investigate the oxidation of polyglycolic acid diesters. Later, the first practically valuable species was made by adding a certain amount of low-activity peroxide. Afterwards, the technology became more and more perfect. At present, the output of anaerobic adhesives in the United States ranks first in the world, and its largest rubber producer is Loctite Corporation. . There are many types of products, each of which is formulated according to certain needs. The viscosity of the rubber ranges from dilute to watery to thick to toothpaste, and the hardness and strength range also vary greatly, being as small as it can be easily disassembled, and it can be used as a high-strength structural adhesive.
From the standpoint of the development of Qingxujiao, there are four generations of first-generation general-purpose anaerobic adhesives, which were developed mainly in the 1960s by polyol esters of methacrylic acid; the second generation was in 1975. The developed polyurethane-modified anaerobic adhesive has developed a second-generation anaerobic adhesive on the basis of this: Subsequently, a large gap-filled third-generation UV-curable anaerobic adhesive has emerged; After the 1980s, an outstanding development of anaerobic adhesives was the realization of microcapsules. The general-purpose anaerobic adhesive is very excellent in performance when used for locking and sealing, but it requires steps such as cleaning screws, gluing, and removing excess glue in use, and has a little pungent odor, which affects its popularization and application. If the anaerobic adhesive is encapsulated in a polymer and becomes dry microcapsules, then the screws are coated together with the adhesive. Such pre-coated screws are "dry" but when screwed into the screw. The capsule is squeezed and the glue flows out. At this time, it cures due to lack of oxygen, and acts as a lock and a seal. This is the result of the perfect combination of the glue type and the gluing process. Some people think that this kind of anaerobic adhesive is the fourth generation of anaerobic adhesive. Its outstanding feature is that it not only retains the characteristics of anaerobic curing, but also better overcomes some of the weaknesses of anaerobic adhesive, making it more suitable for production. The need for development.
Since the research and development of anaerobic adhesives in China in the early 1970s, there have been many applications for brand names. Their performance has been continuously improved, and some new varieties such as microcapsule anaerobic adhesives have also been successfully developed. The Thai company's products are basically similar or similar. The series of its products include the XQ-1, XQ-2, and Y-150 of the Dalian Institute of Chemicals, Chinese Academy of Sciences, and the YY-101#, YY-120#, and YY of the Y-80 Tianjin Synthetic Materials Research Institute. - 301#, YY-2#, etc., KE-1 of Shanghai University of Science and Technology, KYY-1, KYY-2, GY-340, etc. of Guangzhou Institute of Chemistry, Chinese Academy of Sciences. Shanghai Xinguang Chemical Factory's anchor 300#, anchor 350#, etc. Several large serialized products such as GY series, Anchor 300 series, ZY series, HH series and QS series have been formed. The production plants in Dalian, Guangzhou, Shanghai, Yantai, Shandong, the larger production.
In recent years, with the needs of industrial development, special anaerobic adhesives have also emerged continuously, such as rapid curing anaerobic adhesives for continuous operation of production lines, and anaerobic adhesives for special requirements such as oil resistance, water resistance, heat resistance, and impact resistance. There are goods for sale.
Anaerobic adhesive is composed of acrylic monomers, initiators, accelerators, stabilizers. Other additives such as fillers, dyes and pigments, thickeners, plasticizers, thixotropic agents and UV absorbers can also be added as needed.
Acrylic monomer is the main component of anaerobic adhesive, accounting for more than 90% of its total compounding amount. Such monomers include acrylic acid, diesters of methacrylic acid, or certain special acrylates (hydroxypropyl methacrylate) and the like.
Anaerobic adhesives are made up of a variety of components, especially monomers that are ever-changing, and where each component change is likely to gain new properties, there are many varieties of anaerobic adhesives, and their classification methods are not uniform. Under normal circumstances can be classified according to the structure of the monomer, the type and intensity of the monomer, the viscosity, but also according to the purpose of use. The more common classification method is based on the structure and use classification of monomers. Specifically, according to its structure, it can be divided into four categories.
(1) ether type
The structure represented by bis-methacrylic acid triethylene glycol ester.
Common bis-methacrylic acid polyglycol esters (such as the United States Loctite 290 and fumaric acid bisphenol A unsaturated polyester mixed Loctite 271, Loctite 277, etc.); hydroxyethyl methacrylate Or hydroxypropyl ester (such as domestic anchor 302, Japan's triple bond 1030) and so on.
(3) Epoxy esters
It is a product of various structures of epoxy resin and methacrylic acid. Common bisphenol A epoxy ester (such as domestic Y-150, GY-340, etc. is a mixture of epoxy ester and polyglycol ester).
(4) Polyurethane The reaction product of isocyanate, hydroxyalkyl methacrylate and polyol (such as Loctite 372 in the United States, domestic GY-168, anchor 352 and BN-601, etc.). In fact, many anaerobic adhesive products are mixtures or complex compositions that are difficult to classify.
According to the use, it can be divided into fastening and sealing of fasteners, sealing of flange surfaces and pipe joints, adhesive holding and infiltration and plugging. This classification method is simple, easy to remember and easy to use, and is particularly easy for users to accept. Although gum seeds have many uses, there is always a major use that can be used as a basis for classification.
The characteristics of anaerobic adhesive are as follows
(1) Storage is stable in the presence of air or oxygen (usually over 1 year);
(2) It can quickly cure when isolated from air;
(3) A liquid type, low viscosity, easy to infiltrate;
(4) No solvent and little toxicity;
(5) Room temperature curing, high speed, high strength;
(6) Good tightness, high pressure resistance (up to 300.0MPa);
(7) Fast curing at low temperature (0Â°C);
(8) good heat resistance, solvent resistance, acid resistance and alkali resistance;
(9) The residue is easy to remove and can be removed after curing;
(10) Wide range of bonding (good bonding strength to metal and non-metal);
(11) Craftsmanship, easy to use.
Source: 21st Century Fine Chemicals Network
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