First, the crosslinking agent is divided into external crosslinking agent and internal crosslinking agent.

The so-called crosslinking agent is added before use, and then crosslinking reaction occurs at room temperature, heating or irradiation. The external crosslinking agent is divided into the following categories: 　
⑴Polyisocyanate (JQ-1, JQ-1E, JQ-2E, JQ-3E, JQ-4, JQ-5, JQ-6, PAPI, emulsifiable MDI, tetraisocyanate ).
⑵ Polyamines (propylene diamine, MOCA).
⑶ Polyols (polyethylene glycol, polypropylene glycol, trimethylolpropane, trimethylolethane).
⑷Glycidyl ether (polypropylene glycol glycidyl ether).
⑸ Inorganic substances (zinc oxide, aluminum chloride, aluminum sulfate, sulfur, boric acid, borax, chromium nitrate).
⑹Organic substances (styrene, a-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, glyoxal, aziridine).
⑺Organic silicon (ethyl orthosilicate, methyl orthosilicate, trimethoxysilane).
⑻Benzene sulfonic acid (p-toluenesulfonic acid, p-toluenesulfonyl chloride).
⑼Acrylic esters (1,4-butanediol diacrylate, ethylene glycol dimethacrylate, TAC, butyl acrylate, HEA, HPA, HEMA, HPMA, MMA).
⑽Organic peroxides (dicumyl peroxide, bis-2,4-dichlorobenzoyl peroxide).
⑾Metal organic compounds (aluminum isopropoxide, zinc acetate, titanium acetylacetonate).
⑿aziridines
⒀Multifunctional polycarbodiimide crosslinking agent.
⒁Closed crosslinking agent
⒂Isocyanate crosslinking agent

The so-called internal crosslinking agent means that as a monomer, it enters into the macromolecular structure chain during polymerization, or is added to the adhesive as a component, and can be stored stably. Crosslinking can only occur when heated to a certain temperature or radiation conditions. Joint reaction. Commonly used internal crosslinking agents are vinyl monomers, such as acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, divinylbenzene, N- Methyl acrylamide, diacetone acrylamide.

Second, Choose
For different cross-linking agents, the cross-linking agent should be selected, and the cross-linking agent has the following requirements:
⑴The active group of the crosslinking agent can react with the components in the adhesive to form a crosslinking structure.
⑵The cross-linking efficiency is high, and a stable cross-linking structure can be obtained by adding a small amount.
⑶ The cross-linking speed is appropriate, too fast or too slow is not good.
⑷Several cross-linking agents are mixed to obtain the best comprehensive effect.
⑸The cross-linking agent is stable during the process and storage period, and no harmful reaction and cohesion will occur. It is non-toxic, non-irritating and does not pollute the environment.