Boric acid is an inorganic compound with the chemical formula H₃BO₃. It appears as a white crystalline powder with a smooth texture and is odorless. It is widely used in the glass industry, where it enhances the heat resistance, transparency, and mechanical strength of glass products while also shortening the melting process. Additionally, it can be used as a preservative and disinfectant.
Boron-based raw materials are extensively applied in the construction materials industry. According to statistics, boron raw materials are used in construction, enamel, glazes, and glazed tiles. Among these applications, boric acid is particularly prominent in the glass industry.
Applications of Boric Acid in Glass Manufacturing
Acts as a fluxing agent, accelerating glass clarification and reducing its crystallization tendency.
When the B₂O₃ content in glass reaches 15%, it enhances tensile strength, impact resistance, and hardness.
When the B₂O₃ content reaches 12%, it reduces the thermal expansion coefficient, thereby improving the thermal stability of the glass, enhancing its tensile strength, and increasing its surface hardness.
The introduction of boron affects the viscosity of molten glass:
At higher temperatures, boron reduces fluidity.
At lower temperatures, boron increases viscosity.
As a result, high-boron glass has a narrower forming temperature range, which can increase forming speed during mechanized production.
Boric acid enhances the refractive index of glass. Given the same lead content, boron-containing glass exhibits greater luster than non-boron glass.
Boric Acid Consumption in the Glass Industry
According to partial surveys, the glass industry consumes approximately 42% of the world's total boric acid production. The primary uses include:
Borosilicate glass
Textile fiberglass
Insulating glass fibers
In optical glass, laboratory glassware, and heat-resistant glass, adding boric acid improves thermal expansion properties and shortens the melting time.
Typically, boron oxide (B₂O₃) exhibits excellent fluxing properties in low-sodium, high-aluminum glass compositions. This means that in low-sodium glass production, boron compounds can be combined with sodium borate to adjust the sodium-boron ratio in glass.
Boric Acid in Fiberglass Production
Boric acid is also widely used in fiberglass applications, attracting significant attention.
Example: Adding 4-5% B₂O₃ during production aids melting, shortens processing time, prevents devitrification, and enhances water resistance.
New research in China has led to the development of low-magnesium, alkali-free glass fiber formulations. A small amount of boric acid is used to compensate for the missing boron oxide in alkali-free glass, making the process highly cost-effective.
This method is already being applied in the pot furnace production of alkali-free glass fibers.
Experimental results indicate that glass fiber insulation materials are primarily used in new construction projects. Based on this trend, it is reasonable to predict that industrial boric acid will become a major insulation material in the construction industry in the future.
Conclusion
Boric acid plays a crucial role in the glass and construction industries, significantly enhancing glass properties, improving thermal resistance, strength, and production efficiency. With ongoing research and technological advancements, boric acid is expected to become an even more critical material in industrial glass and insulation applications.
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