Anhydrous Zinc Borate is a zinc borate compound without crystalline water, with the chemical formula 2ZnO · 3B2O3. Unlike common hydrated zinc borate (such as 3.5 water zinc borate ZB-2335), anhydrous zinc borate does not have crystalline water in its structure, therefore it has higher thermal and chemical stability.
The main properties of anhydrous zinc borate include:
Appearance: White or light yellow powder.
Density: Approximately 2.8 g/cm ³.
Melting point: above 980 ℃, with extremely high thermal stability.
Solubility: Insoluble in water and most organic solvents, chemically stable.
Thermal stability: Due to the absence of crystalline water, anhydrous zinc borate does not release water at high temperatures, making it suitable for high-temperature processing environments.
The preparation of anhydrous zinc borate is usually carried out by the following methods:
①. High temperature calcination method: Hydrated zinc borate (such as 3.5 water zinc borate) is calcined at high temperature to remove crystal water and obtain anhydrous zinc borate.
②. Direct synthesis method: Anhydrous zinc borate is directly synthesized by reacting zinc oxide (ZnO) and boric acid (H3BO3) at high temperature.
The flame retardant mechanism of anhydrous zinc borate is similar to that of hydrated zinc borate, mainly including the following aspects:
①. Coverage effect: Under high temperature, anhydrous zinc borate decomposes to form a B2O3 glassy film, which covers the surface of the material, isolates oxygen and heat, and prevents flame spread.
②. Inhibition of chain reaction: In halogen containing materials, anhydrous zinc borate reacts with halogen compounds to generate ZnX2 and HX, capturing free radicals generated during combustion and interrupting the combustion chain reaction.
③. High temperature stability: Due to the absence of crystalline water, anhydrous zinc borate can maintain stable flame retardant properties in high temperature environments, making it suitable for high-temperature processing materials.
Anhydrous zinc borate is widely used in the following fields due to its high thermal stability and excellent flame retardant properties:
①. High temperature engineering plastics: In engineering plastics that require high-temperature processing (such as polyamide, polyester, etc.), anhydrous zinc borate can provide stable flame retardant properties.
②. Ceramics and glass materials: In ceramic glazes and glass materials, anhydrous zinc borate serves as a flame retardant and flux, which can improve the thermal stability and flame retardancy of the materials.
③. Fireproof coating: Anhydrous zinc borate is used in fireproof coatings to provide long-lasting flame retardant protection in high temperature environments.
④. Electronic and electrical materials: In high-temperature electronic and electrical materials, anhydrous zinc borate can improve the flame retardancy and electrical properties of the material.
Advantages:
High thermal stability: free of crystalline water, suitable for high temperature environments.
Environmentally friendly and non-toxic: meets the requirements of green chemistry and is environmentally friendly.
Multifunctionality: It combines functions such as flame retardancy, smoke suppression, and enhanced material performance.
limitations:
High cost: The preparation process is complex and the production cost is high.
High dispersibility requirements: Uniform dispersion is required in the material, otherwise it may affect the flame retardant effect.
In the future, research on anhydrous zinc borate will focus on the following directions:
①. Nanotechnology: Improving dispersibility and flame retardant efficiency through nanotechnology.
②. Multi functional composite materials: Develop new composite materials that combine flame retardancy, reinforcement, antibacterial and other functions.
③. Green production process: Optimize production processes, reduce costs, and minimize environmental impact.
Anhydrous zinc borate is a high-performance halogen-free flame retardant with broad application prospects in high-temperature engineering plastics, ceramics, fire-resistant coatings, and other fields due to its high thermal stability, environmental friendliness, and multifunctionality. Through technological innovation and process optimization, anhydrous zinc borate will play a more important role in the field of flame retardant materials in the future.
