Analysis of the progress of research and development of two types of water-based curing agents.

Epoxy
coating
has high hardness, good wear resistance, high adhesion and excellent chemical resistance, and is widely used in the field of coating. Recently, many countries have promulgated environmental regulations restricting volatile organic solvents (VOCs), and the hydration of coatings has become an important trend in the development of coatings. At present, the water-based technology of epoxy resin at home and abroad is mainly divided into emulsification method and salting method 2 categories, emulsification method refers to the direct emulsification of epoxy resin, self-emulsification without emulsifying agent or water-based epoxy curing agent emulsification; Water-based epoxy curing agent emulsified epoxy resin is the most important water-based technology, it can overcome the shortcomings of other water-based methods. The principle of water-based epoxy curing agent modified is to modifie polyamines, basically around type I water-based epoxy curing agent, type II. type water-based epoxy curing agent. According to experts, the "two-type" water-based epoxy resin curing agent research and development progress. Regarding type I water-based epoxy curing agent, the expert said that water-based curing agent and water-based epoxy technology are developed simultaneously, for type I water-based epoxy system, the curing agent is required to have both curing function and emulsification function, the earliest successful development of industrial water-based epoxy curing agent is Thomas Swan Company's Casmide360, and its modified product Casmide362. Early use of alamide polyamine as a cure for type I water-based epoxy system, although it can make liquid epoxy resin emulsified but cured after poor performance, water resistance and chemical resistance, need to be modified to ensure that the performance of curing close to solvent-based epoxy resin coating.
Because of the short application period of the epoxy resin system of polyamide curing agent emulsification, the curing film flexibility is poor, the impact performance is poor, the shortcomings of the coating film brittle, the performance of modified polyamide curing agent is still not ideal, so the curing agent used in type I water-based epoxy system is mainly polyamine polyamine epoxy. Most of the commonly used type I water-based epoxy curing agents are polyamine curing agents for expansion chain, branching, salting, in the molecule to attract non-polar genes, making it with pro-epoxy molecular structure of water dispersion-type curing agent, while it as a cation emulsified epoxy resin, two groups can be mixed into a stable emulsion, the current use of more modified polyamine curing agent is epoxy-polyamine. The preparation method commonly used in epoxy modified polyamine curing agents is generally divided into 2 kinds: the use of polyethylene polyamine and monocyclooxygen or polyoxyoxygen compounds, about 60% of the boamine hydrogen closed, and then with BPA epoxy to achieve an appropriate hydro-hydrophobic oil balance, and then with formaldehyde reaction further hydrogen hydroxylation. This curing agent-cured epoxy system has better gloss, hardness and chemical resistance, in the case of polyamine overdose with BIP A epoxy, and then the adipose monocyclic oxygen or aromatic monocyclooxygen compounds closed boamine hydrogen, after synthesis with water or water-soluble organic solvent dilution, the resulting addition as a clarification solution, and finally added with acetic acid and part of the amine hydrogen. Such as Shimp and other low molecular mass epoxy resin, and polyethylene polyamine reaction to produce polyamine epoxy compounds, and then by monocyclic oxygen compounds to seal it, and with acetic acid in the part of the midamine, in order to regulate the curing agent HLB and reduce the reaction activity of the curing agent, extend the application period.
Later developed a number of new type I water-based curing agent technology, do not need to use organic acid into salt, such as Stark and other use of epoxy resin and excessive interbendylamine, reaction to produce end-of-epoxyamine compound, and then with end-based polyethyl ether reaction to produce aamine, and then by sealing the end of the water-based epoxy curing agent. Since the epoxy resin in type II. water-based epoxy resin system has been pre-provisioned with emulsion, no water-based epoxy curing agent is required to emulsify the epoxy resin, so it only needs to have the function of cross-linking agent. II. The modified nature of type I water-based epoxy curing agents is similar, such as polyamide resin reacts with acetate, phosphoric acid or hydrochloric acid to obtain ammonium salts, and then dissolves in water with the aid of alcohol ether solvents to obtain modified polyamide curing agents. Currently used II. Type II. Water-based epoxy curing agents are mainly adipose amines embedded in hydrophobic polyoxyethylene chain segments, or epoxy-type curing agents produced by shrinking glycerin ether in response to epoxy resins or polyethylene polyamines, or with Polyic acid reaction produces polyamide-type curing agent, which uses the hydrophobicity of polyoxyethylene chain segment to make the curing agent can be distributed in water, and the use of epoxy resin as a chain expander can improve the compatibility of curing agent and epoxy resin. Such as Klein and so on using polyoxyethylene di shrinkage glycerin ether, and BIP A epoxy resin reaction to obtain epoxy resin self-dispersion, and then with polyoxypropylene diamine and isofron diamine reaction to produce epoxyamine curing agent; Klein and so on used bisphenol A epoxy resin, polyoxyethylene di shrinkage glycerin ether and bisphenol A reaction to the epoxy resin dispersion, and then with polyethylene polyamine reaction to produce end-amine-based epoxyamine compound, and finally by sealing the end of the II. type water-based epoxy curing agent.although
methamphetamine is aromatic, but it is involved in curing and has the nature of fatty amines, so some type II. water-based epoxy curing agents are also modified products of inter-benzodiazepin. For example, Mitsubishi Corporation of Japan uses inter-benzodiazepine and epoxy chloropropane to produce epoxy-amine supplements under the action of sodium hydroxide, which is used as a water-based epoxy curing agent with excellent performance. Mitsubishi then reacted G-328 with binary carboxyl acid to obtain polyamide-based curing agents. There are also the use of lipid cyclic amine modified products as water-based epoxy curing agents, such as Vincent and other fatty amines and epoxy resin reaction to produce end epoxy compounds, and then with a lipocyclic amine (PACM) reaction to produce curing agents. Ciba has developed a new type II. water-based epoxy curing agent, a water-soluble epoxyamine compound, and a highly active curing agent is a modified water-soluble epoxy-amine compound that regulates the reaction activity of the curing agent by matching 2 people. It does not require the use of polymeric solvents for solid epoxy dispersions to make O-VOC epoxy coatings, while traditional II. type II. water-based epoxy systems require the addition of polymeric solvents to reduce the concentration of resin Tg to benefit resin particles, which brings volatile organic solvents. This new type II. water-based epoxy curing agent solves this problem.