Mannich Modified Polyamine Curing Agent

Epoxy resin has excellent corrosion resistance, electrical insulation and good physical and mechanical strength, and is widely used in such fields as anti-corrosion coatings, electronics, machinery manufacturing, navigation, aerospace ect. Curing agent is essential components of epoxy resin system,, the performance of epoxy resin curing content is mostly depended by the its property. Therefore, development of a new curing agent is an important way to improve the epoxy resin performance and broaden its applicationThe earliest usage of curing agent is polyamine, which also is still the largest amount in the commercial consumption. Most of polyamine are low viscosity liquid,and it's extremely easy to process. Polyamine's activity is very high to cure epoxy resin rapidly. It can bond various materials fast at room temperature, such as:metal, wood, plastic, ceramic and so on. But the big volatile, high toxicity, severe curing exothermic, and strict ratio of raw materials is the major flaw of polyamine. The effective strategy to overcome these deficiencies is to modify polyamine. Mannich condensation is a relatively simple and effective modification method,which is through the condensation reaction of phenol,aldehyde and amine,to achieve the purpose of modification of polyamine. Mannich condensation product, also known as phenolic amines, can cure epoxy resin at room temperature and humid environment. It occupies an important position among the brands of the room or low temperature curing agent. Phenolic amines are also widely used in heavy-duty industry at the same time.This dissertation focuses on the synthesis of phenolic amines, and the effect of the ratio of raw materials, the type of amine and phenol on the physical and curing properties is discussed in detail. The results show that:increasing the content of phenol or amines induces the reduce of product's viscosity, however, increasing the content of phenol or aldehyde causes the amine value of product reduced. The product with prefect viscosity and amine value can be got by adjusting the ratio of phenol, aldehyde and amine. An increase of alkyl chain length in the aromatic ring of the phenol can improve the mechanical strength of cured resin, but the performance will decrease if the substituted alkyl chain is too long(such as cashew phenol).To overcome the disadvantage of brittleness of the epoxy resin/phenolic amine system, a toughening agent has been synthesized. The toughening agent has such characteristics as colorless, low odor, good epoxy resin compatibility. When 5% of toughening agent is added to the epoxy resin/phenolic amine system, the impact strength of system is improve by 125%, which show that the toughening effect is better than that when the same amout of the commercial toughening reagent CTBN added. Meanwhile, when 5% of toughening agent is added, the tensile strength of system is unchanged. In conclusion, the cheap toughening agent is with highly commercial potential.