Epoxy curing agents mainly have the following types:

1. Aliphatic amines: The main varieties are ethylenediamine, diethylene (triene) triamines, and poly ethylene (support) polyamines. Its characteristic is that, curing at room temperature, curing speed, viscosity low temperature paint, easy to mix with other resins, easy to operate. The coating has high solvent resistance. However, the toxicity is large, heat is released during curing, and the service life is short. The curing is limited by the temperature and humidity conditions, and the paint film is whitened under conditions of high humidity. Produced orange peel, shrinkage and other ills, cured film heat resistance, mechanical strength is poor.

2. Aromatic amines: mainly m-phenylenediamine, m-xylylenediamine, etc. Its characteristic is that it needs to be cured under heating conditions, and it is inconvenient to mix with the resin, and the heat resistance and corrosion resistance of the cured product are more prominent. It is mainly used for heat curing process and can also be used as raw material for modified amine curing agent.

3, amine modified curing agent: The main addition of amine curing agent (such as 590,593 curing agent), T31 curing agent, phenolic amino alcohol curing agent. This mainly focuses on the toxicity problems of aliphatic amines and aromatic amines. It improves the original amine curing agent through addition reaction or condensation reaction. It is characterized by greatly reduced volatility, which is called low toxicity or non-toxic curing agent. Customer service has the drawback of whitening without the induction period. However, the amount of curing agent increases, the amount can be changed within the scope of communication, through the test to determine the optimal dosage range. Due to the introduction of a new molecular structure in the amine-modified curing agent molecule, the coating process performance and the properties of the cured coating are changed to varying degrees, such as the curing at low temperature and humidity, and the corrosion resistance and temperature resistance of the coating film. All can be improved.

4, polyamide curing agent: The curing process is through the end of the polyamide primary and secondary amines on the hydrogen (not through the hydrogen on the amide group) and the epoxy reaction, due to the two sides of the amino molecular distance, after curing The density is small, so the coated film after curing has excellent toughness; and because the amount of polyamide curing agent is not strict, the toughness can be adjusted by the amount of polyamide as needed. Compared with other curing agents, the film's flexibility, impact resistance and adhesion are superior to those of other amine-cured epoxy paints. The coating has good water resistance, but its chemical resistance and solvent resistance are poor, and its viscosity is large. The judo period is required for the coating, and the curing activity is not high. If necessary, it can be used together with other highly active curing agents or accelerators.

5, acid anhydride curing system: acid anhydride and epoxy resin curing and hydroxyl reaction, the reaction is very slow, often requires high temperature curing, even at 200 °C, in the presence of acid or base catalyst, the reaction is rapid. Its coating has good mechanical strength and heat resistance, but after curing, the paint film contains ester bonds and is susceptible to alkali attack. This system is commonly used as a curing agent for epoxy powder coatings and coil coatings, and is supplemented with an imidazole curing agent.

6. Polyisocyanate curing agents: Polyisocyanates react with the hydroxyl groups on the epoxy resin chain. The number of hydroxyl groups on the epoxy chain is increased with the increase of the relative molecular weight of the epoxy resin, so the isocyanate is suitable for curing reaction with a high molecular weight epoxy resin solution (about 30% of the epoxy resin content). The cured product has good acid resistance. Isocyanates are highly reactive with hydroxyl groups in epoxy resins and can be used at low temperatures. They are particularly suitable for curing below freezing.

Sodium Acetate is used as a buffering agent for seasoning, which can alleviate bad odor and prevent discoloration, and has certain anti-mold effect. Sodium acetate can also be used as a sour agent for seasoning, sauerkraut, mayonnaise, fish cake, sausage, bread, sticky cake and so on. Sodium acetate is mixed with methylcellulose and phosphate to improve the preservation of sausages, breads, stickies, etc.

Sodium Acetate

Sodium Ethanoate,Sodium Acetate Sigma,Sodium Acetate And Water,Sodium Acetate Anhydrous

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