How to Establish the Compatibility of Coupling Agent between Organic and Inorganic Substances.

Dec 30, 2020

The common function of coupling agent is to establish compatibility between organic and inorganic materials. For example, to improve the dispersion of nano calcium carbonate in polymer, coupling agent and surface treatment are needed. The introduction of organic groups on the surface of inorganic materials makes it much more compatible with polymers and reduces the problems of migration, precipitation and agglomeration.
This is similar to block polymer or graft polymer (such as graft maleic anhydride) to improve different polar polymers.

Then there is cross-linking. Cross linking is to form a three-dimensional network structure, so that the linear structure becomes the body structure. This requires the use of crosslinking agents, common peroxide, such as DCP and so on. Look at the crosslinking of polyethylene, curing of epoxy resin and vulcanization of rubber. You will have a clear understanding of crosslinking.Crosslinking, the word used in plastics, is called crosslinking
Vulcanization is used in rubberCrosslinking agent, also known as bridging agent, is an important part of polyolefin photoresist. The photochemical curing of this photoresist depends on the reaction of crosslinking agent with double photosensitive functional groups. After exposure, the crosslinking agent produces double free radicals, which interact with polyolefin resin to form bridge bonds between polymer molecular chains and become insoluble substances with three-dimensional structure.

It is usually a substance with multiple functional groups in the molecule, such as organic dibasic acid, polyol, etc.; or a compound with multiple unsaturated double bonds in the molecule, such as divinylbenzene and diisocyanate, N, n-methylenebisacrylamide (MBA), etc. It can be fed together with monomers and crosslinked after polycondensation (or polymerization) to a certain extent, so that the product becomes insoluble crosslinked polymer; it can also retain a certain number of functional groups (or double bonds) in linear molecules, and then add specific substances for crosslinking, such as curing of phenolic resin and vulcanization of rubber.

Crosslinking agent is mainly used in polymer materials (rubber and thermosetting resin). Because the molecular structure of polymer materials is like a long line, without crosslinking, the strength is low, easy to break, and there is no elasticity. The role of crosslinking agent is to produce chemical bonds between the linear molecules, so that the linear molecules are connected with each other, forming a network structure, so as to improve the strength and elasticity of rubber. The crosslinking agent used in rubber is mainly sulfur, and in addition, accelerators should be added.
1. Crosslinking and modification of various thermoplastics (polyethylene, polyvinyl chloride, chlorinated polyethylene, EVA, polystyrene, etc.). The addition of DCP is 0.2-1% in addition to 1-3% in thermal crosslinking and 0.5-2% in irradiation crosslinking. After crosslinking, the heat resistance, flame retardancy, solvent resistance, mechanical strength and electrical properties of the products can be significantly improved. Compared with the peroxide crosslinking system, it can improve the product quality significantly and has no peculiar smell. It is typically used in polyethylene, polyethylene / chlorinated polyethylene, polyethylene / EVA cross-linked cables and polyethylene high and low foaming products.
2. The auxiliary vulcanization of ethylene propylene rubber, various fluororubber, CPE and other special rubber (used together with DCP, the general dosage is 0.5-4%) can significantly shorten the vulcanization time, improve the strength, wear resistance, solvent resistance and corrosion resistance.
3. Crosslinking of acrylic acid and styrene ion exchange resin. Compared with divinylbenzene crosslinking agent, it has the advantages of low dosage, high quality, anti fouling, high strength, large pore size, excellent heat resistance, acid and alkali resistance and oxidation resistance. This is a new type of ion exchange resin which is newly developed at home and abroad.
4. Modification of polyacrylate, polyalkylacrylate, etc. It can improve the heat resistance, optical properties and processability. It is typically used for heat resistance modification of common PMMA.
5. Epoxy resin, DAP (diallyl polyphenylene dicarboxylate) resin modification. It can improve heat resistance, adhesion, mechanical strength and dimensional stability. It is typically used for modification of epoxy potting and encapsulating materials.
6. Crosslinking and modification of unsaturated polyester and thermoplastic polyester. It can significantly improve the heat resistance, chemical corrosion resistance, dimensional stability, weatherability and mechanical properties. It is typically used to improve the heat resistance of hot pressed unsaturated polyester FRP products, and the service temperature of the modified products can reach above 180 ℃.
7. Poly (Triallyl isocyanate), the homopolymer of TAIC, is a kind of transparent, hard, heat-resistant resin with excellent electrical insulation. It can also be used to bond glass and ceramics. It is typically used to make multilayer safety glass.
8. Transparent and shatter resistant products can be prepared by internal plasticization of polystyrene and copolymerization of styrene and TAIC.
9. TAIC prepolymer is the protective agent of metal heat resistance, radiation resistance and weather resistance. The coating has excellent heat resistance, radiation resistance, weather resistance and electrical insulation. The typical insulation materials used in manufacturing microelectronic products are printed circuit board and so on.
10. It can be used as the intermediate of UV curable coatings, photoresist, flame retardant and flame retardant crosslinker. It is typically used to synthesize high efficiency flame retardant TBC and flame retardant crosslinking agent DABC.