Common knowledge of coating: three methods of modifying waterborne epoxy curing agent

At present, the water-based technology of epoxy resin at home and abroad is mainly divided into emulsification method and salt forming method The emulsification method refers to the direct emulsification of epoxy resin, self emulsification without additional emulsifier or emulsification of waterborne epoxy curing agent, while the salification method is to modify epoxy resin into resin rich in acid or alkali, and then neutralize it with alkali or acid of small molecular weight Waterborne epoxy curing agent emulsion epoxy resin is the most important waterborne technology, which can overcome the shortcomings of other waterborne methods Most of the commonly used water-borne epoxy curing agents are polyamines or their modified products, and the modified products mainly use the amino groups in their molecules Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings: at present, the waterborne technology of epoxy resin at home and abroad is mainly divided into emulsification method and salt forming method The emulsification method refers to the direct emulsification of epoxy resin, self emulsification without additional emulsifier or emulsification of waterborne epoxy curing agent, while the salification method is to modify epoxy resin into resin rich in acid or alkali, and then neutralize it with alkali or acid of small molecular weight Waterborne epoxy curing agent emulsion epoxy resin is the most important waterborne technology, which can overcome the shortcomings of other waterborne methods Most of the commonly used water-borne epoxy curing agents are polyamines or their modified products, in which the modified products mainly use the active hydrogen on the amine group in the molecule to react with the epoxy group in the epoxy resin molecule According to experts, there are three modification methods commonly used for polyamines, all of which introduce non-polar groups into the polyamine molecular chain, so that the modified polyamine curing agent has amphiphilic structure, so as to improve the compatibility with epoxy resin The first is the modification of amidated polyamines Amidated polyamines have certain water solubility or water dispersibility, which can be used as curing agent of waterborne epoxy resin without the aid of cosolvent or emulsifier The low molecular weight liquid epoxy resin does not need to be pre emulsified, but is mixed and emulsified by amidated polyamine before construction The waterborne epoxy system made of amidated polyamine Emulsified Epoxy resin has the advantages of good construction performance and long application period However, experts also said that the compatibility of amidated polyamine curing agent modified by monofatty acid with epoxy resin is not good, and phase separation is easy to occur, and surface defects such as oil slick and pit appear on the surface of the film, and insufficient curing results in poor chemical resistance and moisture resistance of the film The second is the modification of polyamide The waterborne polyamide curing agent is prepared by condensation of two polyacids and polyamine This modification can improve the compatibility with epoxy resin, and the surface defects on the surface of the film will not appear However, the epoxy resin system with polyamide curing agent has a shorter application period, and generally does not gel for more than 1 hours This will bring some trouble to the construction Experts said that the polyamide cured film has poor flexibility, impact performance and embrittlement Due to the existence of unsaturated double bond in dimeric acid during synthesis, water-based polyamide curing agent is easy to be oxidized by oxygen in the air, resulting in the darkening of curing agent color, which is not suitable for curing agent of water-based epoxy floor coating with high color requirements This method has some limitations, of course, it does not cover up the advantages of its application The final method is polyamine epoxy adduct Experts said that due to the more or less defects of the film cured with amidated polyamide and polyamide water-based curing agent, and the performance of the modified film has not been significantly improved, so the water-based epoxy curing agent used abroad is polyamine epoxy adduct, which uses the reaction of epoxy resin and polyamine to introduce the epoxy resin molecular chain into the polyamine molecular chain, so as to make the synthesized film solid Reducing the content of primary amine group in curing agent can obviously reduce the activity of curing agent The application period of the epoxy system emulsified with this type of waterborne epoxy curing agent is prolonged, and the embrittlement of the film is improved by adding polyalkyl polyamine oxide The expert also said that if the water-based epoxy curing agent is to have the function of emulsifying epoxy resin, it needs to be obtained by introducing an oxidized alkyl chain segment or an ionic group into the curing agent molecular chain Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,