Phenolic curing agent for high-temperature-resistant and high-hardness epoxy resin powder coating and preparation method

Abstract

The invention discloses a phenolic curing agent for high-temperature-resistant and high-hardness epoxy resin powder coating and a preparation method. The curing agent is prepared from the following raw materials in parts by mole: 4-8 parts of p-cresol, 5-9 parts of formaldehyde, 2-4 parts of 2, 6-dimethyl phenol, 10-17 parts of resorcinol diglycidyl ether, 4-9 parts of 1,6-hexanediol diglycidyl ether, 7-13 parts of hydrogenated bisphenol A, 3-6 parts of resorcinol, a catalyst and a pH regulator. The phenolic curing agent is obtained by chain extension and end capping of low-molecular-weight phenolic aldehyde, and is high in functionality; molecular structures are all ether bond links, the curing activity of end groups is high, and finally, a coating film formed by low-temperature curing ofthe phenolic curing agent and E-12 epoxy resin at 160 DEG C is high in crosslinking density, high in hardness, high in adhesive force, resistant to high temperature for a long time and excellent in gasoline resistance.

Description

technical field [0001] The invention belongs to the field of powder coatings, and relates to a preparation method of a phenolic curing agent for epoxy resin powder coatings and a phenolic curing agent prepared by the method. Background technique [0002] With the development of the powder coating market, it has become one of the most commonly used products for metal surface coating. As a special powder coating curing agent in the field of pipeline anticorrosion, phenolic curing agent has developed rapidly in the powder coating market in recent years. [0003] Ordinary phenolic curing agents are generally obtained by chain extension of linear liquid epoxy resin E-51 and bisphenol A. The product has a low degree of molecular branching and is cross-linked with the cured coating film of E-12 epoxy resin. Low density and poor corrosion resistance. [0004] Chinese patent ZL201611039784.4 uses E-51 epoxy resin and dihydrazide compound to modify, and then seals with bisphenol A t...

AI Technical Summary

Problems solved by technology

[0003] Ordinary phenolic curing agents are generally obtained by chain extension of linear liquid epoxy resin E-51 and bisphenol A. The product has a low degree of molecular branching and is cross-linked with the cured coating film of E-12 epoxy resin. Low density, poor corrosion resistance

[0004] Chinese patent ZL201611039784.4 uses E-51 epoxy resin and dihydrazide compound to modify, and then seals with bisphenol A to obtain phenolic curing agent. Although it can improve the functionality of the product, it also brings some defects. For example, substances with a dihydrazide structure have poor heat resistance, and are easily yellowed and destroyed at high temperatures. At the same time, because the molecular weight is too large, the number average molecular weight reaches about 6000, and the chain segment is soft, and the activity of the end group is low, so it cannot be used for high temperature resistance and It is used in fields that require high hardness

[0005] In Chinese patent ZL201710962292.0, amino silane is added to improve the high temperature resistance of the product, but its hardness and high temperature resistance still cannot achieve satisfactory results

[0006] At present, when high-temperature equipment (such as ovens, drying rooms, etc.) However, ordinary powder coatings (including phenolic curing agent system powder coatings) have the problem that long-term high-temperature performance, hardness and gasoline resistance cannot meet the requirements at the same time

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