Zinc borate is an environmentally friendly non halogen flame retardant, characterized by non toxicity, low water solubility, high thermal stability, small particle size, and good dispersibility. With the widespread application of engineering plastics in fields such as automotive, electronics, and construction, the demand for flame retardant properties of materials is increasing day by day. Zinc borate has become an important flame retardant additive in engineering plastics due to its excellent flame retardant properties and environmental characteristics.
The chemical composition of zinc borate is XZNO · YB2O3 · ZH2O, and the common variety is 3.5 water zinc borate (ZB-2335). Its physical properties include white or light yellow powder appearance, particle size of 3-5 microns, specific gravity of about 2.67 g/cm ³, and melting point of about 980 ℃. In terms of chemical properties, zinc borate is insoluble in water, has high thermal stability, and loses crystallization at temperatures above 320 ℃.
The flame retardant mechanism of zinc borate mainly includes:
① Heat absorption effect: releases crystalline water at high temperatures, absorbs a large amount of heat, and lowers the surface temperature of the material.
② Coverage function: Decompose to form a B2O3 glassy film, covering the surface of the material and isolating oxygen and heat.
③ Inhibition of chain reaction: Reacts with halogen compounds to generate ZnX2 and HX, captures free radicals, and interrupts the combustion chain reaction.
① Polyvinyl chloride (PVC): In rigid PVC, zinc borate can completely replace antimony oxide, achieving similar flame retardant effects while significantly reducing smoke density. Combining with antimony oxide in soft PVC can improve flame retardancy.
②Polypropylene (PP) and polyethylene (PE): The synergistic use of halogen-free flame retardants such as zinc borate and magnesium hydroxide can improve flame retardancy and reduce smoke generation.
③ Reinforced polyamide and epoxy resin: In these high-performance engineering plastics, zinc borate serves as a multifunctional additive that not only enhances flame retardancy but also improves the mechanical and electrical properties of the material.
Advantages:
Environmentally friendly and non-toxic, meeting the requirements of green chemistry.
Synergistic effect with multiple flame retardants to enhance flame retardancy.
Multi functional, with characteristics such as flame retardancy, smoke suppression, and corrosion resistance.
limitations:
The effect of using it alone in soft PVC is poor, and it needs to be compounded with other flame retardants.
The cost is relatively high, which may increase the production cost of materials.
In the future, research on zinc borate flame retardants will focus on the following directions:
①Nanotechnology: Improving dispersibility and flame retardant efficiency through nanotechnology.
②Multi functional composite materials: Develop new composite materials that combine flame retardancy, reinforcement, antibacterial and other functions.
③Green production process: Optimize production processes, reduce costs, and minimize environmental impact.
Zinc borate flame retardant has a wide range of application prospects in engineering plastics due to its excellent flame retardant properties and environmental characteristics. Through technological innovation and process optimization, zinc borate will play a more important role in the field of flame retardant materials in the future.
