Melamine cardanol modified curing agent preparation method

Abstract

The invention discloses a melamine cardanol modified curing agent preparation method, which comprises: uniformly mixing 140-155 parts of cardanol, 28-40 parts of paraformaldehyde and 5-15 parts of melamine, adding 20-110 parts of an amine compound in a dropwise manner, controlling the temperature at 30-50 DEG C, carrying out a reaction, carrying out thermal insulation after completing the adding,and continuously carrying out a reaction for 1-3 h; adding 140-155 parts of cardanol and 28-40 parts of paraformaldehyde, controlling the temperature at 40-50 DEG C, adding 20-110 parts of an amine compound in a dropwise manner, carrying out thermal insulation after completing the adding, and continuously carrying out a reaction for 1-3 h; adding an organic solvent into the reaction solution, stirring and uniformly mixing, and carrying out thermal insulation standing layering to obtain an upper-layer organic phase and a lower-layer water phase; and carrying out pressure reducing distillation on the obtained upper-layer organic phase to obtain the melamine cardanol modified curing agent. According to the present invention, the prepared modified cardanol curing agent product cannot produce turbidity after being placed for 6 months, the surface smoothness of the paint film cannot be affected during the application of the prepared modified cardanol curing agent product, and the good effectis achieved.

Description

technical field [0001] The invention relates to a preparation method of a melamine cardanol modified curing agent. Background technique [0002] Cardanol is extracted from natural cashew nut shell oil by advanced technology, and can replace or partially replace phenol for the manufacture of epoxy curing agent, liquid phenolic resin, liquid or powdered thermosetting phenolic resin. [0003] At present, my country is a country with a large demand for cardanol, and it is also the most important importer of cashew nut shell liquid in the international market. Due to the renewable nature of cardanol, it has been paid more and more attention, which can save social resources. In the application of cardanol, it is mainly the preparation of cardanol curing agent. The prepared curing agent is cured with epoxy resin at high temperature to obtain a paint film with corrosion resistance, high temperature resistance and good operation at low temperature. The obtained paint The film is mai...

AI Technical Summary

Problems solved by technology

At present, the main domestic manufacturers of cardanol curing agent synthesis are: Shanghai Meidong Biomaterials Co., Ltd., Cardolite Zhuhai Co., Ltd., etc., they mainly use cardanol, aldehydes (formaldehyde, paraformaldehyde, paraformaldehyde), polyamines (or mixed amine) carries out Mannich reaction and makes cardanol solidifying agent, exothermic heat is too violent when adding paraformaldehyde to carry out reaction due to one-time addition, and operation risk is very high; Therefore usually adopt the method for adding paraformaldehyde in batches, After the reaction, excess polyamines and aldehydes and the water produced by the reaction have the following defects in this process: the amine compounds (polyamines) are substantially excessive in the reaction process, and when the reaction is completed, the vacuum distillation process is basically Difficult to clean amine compounds (polyamines)

Secondly, when amine compounds (polyamines) use small molecular amines, there are still the following disadvantages: small molecular amines are highly volatile and toxic, and the residual small molecular amine compounds affect the paint film performance of the product, resulting in the appearance of the paint film. There are serious defects such as oily surface and white film

In the process of this preparation method, cardanol, paraformaldehyde, melamine and amine compounds undergo Mannich reaction, and the reaction temperature is 80-90°C. At such a high temperature, a large amount of melamine will undergo its own polymerization side reaction, A large amount of dimer and polymer products are produced, the self-polymerization product of melamine is solid and remains in the product, and the self-polymerization product of melamine is a fine solid, which is difficult to separate from the modified cardanol curing agent product, and filtered After being placed for 3 days, there is still solid precipitation, and there is still solid precipitation at low temperature, and the product after precipitation is turbid. Although there is a melamine curing agent in the modified cardanol, the product is turbid and cannot be applied to the smear layer. There is a large amount of Turbidity, which will affect the surface smoothness of the paint film when applied

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