Preparation method of phenol-formaldehyde resin for magnesia carbon bricks

The invention discloses a preparation method of phenolic resin for magnesia-carbon bricks. The specific implementation steps are as follows: first, phenol and formaldehyde are put into a reaction vessel according to a certain feeding ratio, and a certain amount of TEOS is added under stirring conditions, and a certain amount of NaOH is added. The solution is heated and reacted, and the reaction temperature is controlled below 95°C. Then add a certain amount of acetic acid to the reaction solution to adjust the pH value of the reaction solution between 6 and 7, and finally adopt vacuum dehydration to obtain the phenolic resin. The raw materials used in the present invention are phenol and formaldehyde, wherein the molar ratio of phenol, formaldehyde and NaOH is 1:1.2~1.4:0.05~0.1, the added TEOS modifier accounts for 1.5%~2.5% of the raw material mass, and the reaction temperature is 85 ℃~95℃, the reaction time is between 2h~3h, the temperature is controlled at 60~75℃ during the vacuum dehydration process, and the pressure is 0.08~0.09Mpa. The phenolic resin binder obtained by the invention has a low residual carbon rate and a greatly increased viscosity, can effectively suppress cracking and bubbling of the carbonized layer, and is greatly beneficial to the improvement of the performance of refractory products.