Advantages and Disadvantages of Phenolic Modified Epoxy Resin Curing Agent

A primary agent made from primary or secondary amine, formaldehyde and phenol by Mannich reaction has its main advantages:

(1) after phenolic modified amine curing agent are liquid, low viscosity, and easy to miscible with epoxy resin, greatly facilitate the operation of the user;

(2) to improve the low-grade fatty amine volatile high, irritation, toxicity of large defects, is conducive to protecting the operating environment and the operator's health;

(3) due to the introduction of phenols and aldehydes in the molecule, the molecular chain is lengthened, the relative molecular mass increases, the proportion of active hydrogen in the molecule is relatively reduced, so the proportion of curing agent and epoxy resin increased, Than the requirements are not strict, curing speed can also be adjusted according to requirements;

(4) the introduction of phenolic hydroxyl molecules, enhanced curing reaction activity, therefore, can be at room temperature, low temperature (even at 0 ℃ or so), damp environment curing;

(5) the introduction of phenolic skeleton structure within the molecule to improve the heat distortion of epoxy resin curing temperature;

(6) has good chemical resistance, moisture resistance, good appearance and moderate color stability. However, because of the short service life of such Mannich alkali curing agents, the lack of elasticity (or toughness), unsatisfactory water resistance and seawater resistance, make people continue to study and develop new and excellent performance of the new curing agent.

Into the 21st century, China's epoxy resin R & D technology and application of the rapid expansion of the demand for epoxy resin to 20% to 30% of the rate of growth. China's epoxy resin production in 2004 can be close to 300,000 t, the total consumption of about 600,000 t, is expected before and after 2010, China's epoxy resin production capacity will reach 1 million t / a. Products are gradually to the fine, professional, serialization, high purity, high performance, diversification and other development. Popular products will form a large scale and high purity, special products will form a high performance and professional. In this situation with the matching curing agent products must keep up with the development of epoxy resin, which curing agent research and development to create a good opportunity, while the curing agent brand, quality, application of a more High demand. In all curing agent in the amine curing agent accounted for a prominent position, the largest amount, the largest variety, about 80% of the total amount of curing agent.

The high performance and specialization of phenolic modified amines will be the mainstream of development. It is expected that the demand for phenolic modified amine will reach 30,000 tons in 2005. The varieties of phenolic modified amine curing agents are also limited to the modification of polyamines, aromatic amines and alicyclic amines, although the introduction of tung oil or other organic acids therein involves the addition of flexible chains to improve the brittleness and adhesion of such curing agents Force, but still not enough. Developed long-chain alkylphenols such as nonylphenol, octylphenol, bisphenol A; mixed amine instead of monoamine, polyalkoxylenediamine, polyalkoxylated polyamine; p-hydroxybenzaldehyde, isobutyraldehyde And other places to replace formaldehyde and other aspects of research to meet the water conservancy projects, construction, electrical and electronic industry on low toxicity, low temperature, water curing agent a large number of needs to catch up with foreign varieties, specialization, high performance level of development.