Preparation method of boron modified phenolic resins

Abstract

The invention relates to a preparation method of boron modified phenolic resins, which includes the steps of: (1) preparing raw materials according to the following components, by weight, 1000 parts of phenol, 480-500 parts of formaldehyde, 10-20 parts of a catalyst, and 300-400 parts of a boric acid; (2) putting the phenol and the formaldehyde in a reaction kettle, controlling the temperature at 50 DEG C and adding half of the catalyst, and then reacting for 1 hour at a temperature of 63 DEG C to 67 DEG C; (3) smoothly heating the material to a temperature of 90 DEG C, and adding 1 / 10 of the boric acid; (4) maintaining the material temperature between 90 DEG C and 100 DEG C, and finishing adding the residual boric acid in 0.5 hour; (5) adding the residual catalyst in mixing components; (6) regulating and controlling a medium temperature, making the material temperature rise to 110 DEG C-120 DEG C in 0.5 hour, and carrying out constant temperature reaction for 2 hours; and (7) after the dehydration reaches a theoretical value, taking samples and measuring gel time, and preparing and obtaining the boron modified phenolic resins. Compared with the prior art, the preparation method of the boron modified phenolic resins has the advantages of stable reaction, strong controllability and high carbon yield of the resins.

Description

technical field [0001] The invention relates to a method for preparing a modified phenolic resin, in particular to a method for preparing a boron-modified phenolic resin, which can be used in the fields of aerospace, military and braking materials, electric carbon materials, friction materials, refractory materials, etc. widely used. Background technique [0002] Currently, there are three main methods for modifying phenolic resins with boron compounds. ①Introduce the boron compound at the end of the synthesis of the phenolic resin or the early stage of the use process, so that the boron compound first enters the phenolic resin in a physical mixing manner, and then reacts with the boron compound and the phenolic resin during the high-temperature curing stage to form part of the B-O bond, thereby improving the phenolic resin. Resin performance, because the boron element fails to fully react with the phenolic resin, the overall performance has not fundamentally changed. ②Rea...

AI Technical Summary

Problems solved by technology

①Introduce the boron compound at the end of the synthesis of the phenolic resin or the early stage of the use process, so that the boron compound first enters the phenolic resin in a physical mixing manner, and then reacts with the boron compound and the phenolic resin during the high-temperature curing stage to form part of the B-O bond, thereby improving the phenolic resin. Resin performance, because the boron element failed to fully react with the phenolic resin, the overall performance did not fundamentally change

②Reaction with boron compounds and phenols to generate boron-containing phenyl esters, and then react with formaldehyde to generate boron-modified phenolic resins. This method has many shortcomings: a. Long esterification time, high temperature, and a large amount of phenol during condensation With the loss of reaction water, the molar ratio is uncontrollable

This method also has many disadvantages: a. The reaction time is long and the temperature control is difficult.

The patent is to add boron compound to the synthesized B-stage phenolic resin. Only in the curing process of the resin can the boron compound participate in the reaction. The utilization rate of the boron compound is low, and the addition amount is about 5%.

Although this method improves the carbon residue rate and heat resistance of phenolic resin, the carbon residue rate of the synthesized resin can only reach 60-65%.