Preparing method for amino-terminated polyurethane for improving tenacity of cured epoxy material

Abstract

The invention discloses a preparing method for amino-terminated polyurethane for improving tenacity of a cured epoxy material. The preparing method includes the following steps that 1, in the presence of a catalyst, polyether glycol and diisocyanate are polymerized in the nitrogen atmosphere; 2, the product is cooled to room temperature, and a viscosity modifier is added to obtain a prepolymer solution; 3, the temperature is kept at 2-10 DEG C, the product in the step 2 is added into an aliphatic polyamine solution, the mixture is heated to 40-50 DEG C, the temperature is kept for 1-3 h, and amino-terminated polyurethane for improving tenacity of the cured epoxy material is collected from a reaction product. The method is simple, polyamine terminal seal with primary amine and secondary amine is involved, the application range is wider, the polymerization success rate is up to 95%, the gel crosslinking phenomenon occurs rarely, the prepared amino-terminated polyurethane molecular chain is uniform and regular, molecular weight distribution is reasonable, and the average molecular weight approaches the theoretical value.

Description

technical field [0001] The invention relates to a preparation method of amino-terminated polyurethane. Background technique [0002] Amino-terminated polyurethane is a kind of urethane polymer terminated by aliphatic polyamines. Because there are hydrophilic alcohol ether groups and amine groups in the molecular chain, and there are lipophilic alkyl long chains, it can It can be used in various fields without being limited by the environment and taboos. Amino-terminated polyurethane is mainly used in coatings, coatings, and adhesives industries, especially as a new type of modified amine curing agent containing both rigid crystal units and flexible chains. In the process of combining with epoxy resin, it not only improves the environment The compatibility of epoxy resin and curing agent facilitates the curing reaction, and can also be used as an emulsifier to make the epoxy system water-based. In addition, due to the introduction of polyurethane toughness groups into the e...

AI Technical Summary

Problems solved by technology

[0003] At present, there are many public reports on the application of amino-terminated polyurethanes as epoxy toughening agents, but most of the preparation methods are unclear, or the methods are only applicable to specific raw material systems, and the generalization is not strong

For example, Guan Jianguo and Sun Tao of Wuhan University of Technology first used short-chain hexanediol to synthesize hexanediol-type amino-terminated polyurethane, and used it to form an adhesive with E-44 epoxy resin, but because the flexible chain segment of hexanediol is too short , although the adhesive has high bonding strength, but low flexibility

Then, they used polyethylene glycol instead of hexylene glycol to synthesize polyethylene glycol-type amino-terminated polyurethane. The curing agent introduced a longer flexible chain segment to significantly improve the flexibility of the cured system. However, the preparation method they used There is a large gap between the theoretical molecular weight and the actual value of the polymer, and the controllability of the reaction is limited

Patent CN1035302A describes a method for synthesizing an anionic polyurethane dispersion with a network structure, and patent 1511880A discloses a method for crosslinking cationic polyurethane with amino-terminated dendrites or hyperbranched polymers to achieve water-based properties. These two methods have their own characteristics. However, because the prepared polyurethane is ionic, it must go through the process of neutralization and salt formation, which is cumbersome.

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