Preparation of ultrafine zinc borate

Preparation of ultrafine zinc borate
The particle size of the zinc borate flame retardant powder is too large to disperse in the base material, and the use performance of the material will be deteriorated when the addition amount is high. In order to improve the dispersibility of zinc borate in the base resin, the particle size and particle size distribution must be smaller. Therefore, the flame retardant is miniaturized or even nano-sized, which can increase the contact surface of the flame retardant and the material to improve compatibility, and can also reduce the amount of flame retardant. The synthesis and application of zinc borate abroad has reached a certain level. The new zinc borate product of American Borax Company reported in 1990 has an average particle size of 2-4μm; in 1992, Borax Company reported a new product of zinc borate. Its water loss temperature is 413 ℃ (about 110 ℃ higher than standard zinc borate), so it can be used for engineering plastics with extremely high processing temperature, such as polyketones, sulfones and polyether imines.
The particle size of zinc borate produced in China is generally 2-8 μm, which still cannot reach the level of foreign countries, so the ultra-fine research of zinc borate is becoming more and more important.
Wuhan University mixes zinc oxide and boric acid evenly, the ratio of the substance is 1:3, adds to the reaction vessel, the amount of water added is 0.01%-60.00% of the total mass of zinc oxide and boric acid, and then stirs to prepare a rheological state, and then put Put it into a closed container and keep it at 60-100 ℃ for 6-12 h, cool to room temperature to take out the product, and dry it at 120-140 ℃. The preparation process of this method does not require filtration or washing with water, and the reaction yield is high.

Hu Yunchu invented a solid-phase reaction method for preparing nano-zinc borate. Grind zinc oxide and boric acid into micrometers respectively, and then add 1%-5% of the total amount of sodium stearate, silane and other surfactants or coupling agents in a certain proportion, and then perform ball milling or vacuum ball milling, and finally Obtained nano-scale zinc borate.
Others have studied the preparation of low-hydrated zinc borate with controllable morphology by hydrothermal method and the preparation of zinc borate by solvothermal modification method, both of which have obtained well-modified products.