Crosslinking agent, also known as bridging agent, is an important component of hydrocarbon photoresist. The following is a detailed introduction about crosslinking agents:
1、 Definition and Properties
Crosslinking agent is a substance that can form bridging bonds between polymer molecular chains, transforming the polymer from a linear structure to a three-dimensional network structure. It is usually a substance containing multiple functional groups in its molecule, such as organic dicarboxylic acids, polyols, etc; Or compounds containing multiple unsaturated double bonds within the molecule, such as divinylbenzene and diisocyanates, N, N-methylbisacrylamide (MBA), etc.
2、 Mechanism of action
The main mechanism of action of crosslinking agents is to initiate free radical reactions or utilize functional groups to react with polymers. Specifically, after exposure to crosslinking agents, double free radicals are generated, which interact with the hydrocarbon resin to form bridge bonds between polymer molecular chains, thereby forming insoluble substances with three-dimensional structures. This three-dimensional structure significantly enhances the strength and elasticity of the polymer.
3、 Application Fields and Effects
Crosslinking agents have a wide range of applications in polymer materials (rubber and thermosetting resins), with the following specific effects:
Crosslinking and modification of various thermoplastic materials such as polyethylene, polyvinyl chloride, chlorinated polyethylene, EVA, polystyrene, etc. Cross linking can significantly improve the heat resistance, flame retardancy, solvent resistance, mechanical strength, and electrical properties of the product. For example, it has significant applications in polyethylene, polyethylene/chlorinated polyethylene, polyethylene/EVA cross-linked cables, and polyethylene high and low foaming products.
Assisted vulcanization of special rubbers such as ethylene propylene rubber, various fluororubbers, and CPE. It can significantly shorten the vulcanization time, improve strength, wear resistance, solvent resistance, and corrosion resistance.
Crosslinking of acrylic and styrene type ion exchange resins. Prepare ion exchange resins with excellent properties such as anti fouling, high strength, large pore size, heat resistance, acid and alkali resistance, and oxidation resistance.
Modification of polyacrylic esters, polyacrylic esters, etc. Significantly improve heat resistance, optical performance, and processability.
Modification of epoxy resin and DAP (diallyl phthalate) resin. Improve heat resistance, adhesion, mechanical strength, and dimensional stability.
4、 Dosage and addition method
The dosage and addition method of crosslinking agent vary depending on the specific application scenario. For example, in the process of thermal crosslinking, the general addition amount is 1-3%, and an additional 0.2-1% of diisopropylbenzene peroxide (DCP) may need to be added; During the irradiation crosslinking process, the addition amount is 0.5-2%, and DCP can be omitted.
5、 Summary
Crosslinking agents, as an important chemical additive, play a crucial role in the modification of polymer materials. By forming chemical bonds between linear molecules, crosslinking agents can significantly enhance the strength and elasticity of materials, improve their heat resistance, flame retardancy, solvent resistance, and other properties. Therefore, crosslinking agents have broad application prospects in industrial fields such as rubber, plastics, and coatings.
