Industrial grade 96% Boric acid CAS 11113-50-1

What is Boric acid?

Boric acid (also known as orthoboric acid or boracic acid) is an important oxyacid of boron and one of the most widely used boron compounds in the glass industry and agriculture. Its chemical formula is often written:

H3BO3 (CAS No.: 10043-35-3, EINECS No.: 233-139-2, molecular weight: approximately 61.83)

It is a colorless to white crystalline powder, a flaky or granular solid at room temperature, odorless, and has a melting point of approximately 170.9℃ (it decomposes on melting and dehydration). When heated it loses water in turn to form metaboric acid (HBO2) and boron oxide (B2O3). Relative density is about 1.44. It is soluble in water (solubility about 2.5g/100mL at 0℃, about 27.5g/100mL at 100℃) and its aqueous solution is weakly acidic.

In terms of molecular arrangement, boric acid has a planar triangular B(OH)3 structure, and the central boron atom has only 6 valence electrons, which is a typical electron-deficient compound. Boric acid in water does not ionize directly to give hydrogen ions but acts as a Lewis acid and accepts hydroxyl ions from water molecules (B(OH)3 + H2O → B(OH)4- + H+). This property of a ‘electron-deficient acid’ allows it to complex with polyhydroxy compounds and also to enter the silicon-oxygen network structure of glass melts as a network forger and flux. This is the structural basis for boric acid to become an important raw material in the glass industry.

Chemically, boric acid is a very weak acid, possessing mild properties and weak antibacterial and preservative effects. It is dehydrated by heating to form boron oxide, and reacts with alcohols to form borate esters. Boric acid is low in toxicity, but there are health risks from excessive intake or prolonged exposure. It is classified as a Group 1B reproductive toxicant by the EU and its use in food and cosmetics is limited by the relevant regulations. Store in a sealed, moisture proof container.

Industrial grade boric acid is a product for industrial uses such as glass, ceramics, flame retardants and agriculture, with a purity typically above 99%. The following indicators of industrial-grade products have higher requirements than reagent-grade:

Water-insoluble matter

Low water-insoluble matter content is required to ensure clear solution and clean glass melt.

sulfates and chlorides

Impurities such as sulfates and chlorides affect glass quality and agricultural applications, and must be controlled within standard limits.

Iron content

Iron content affects the transparency and color of glass products and is an important quality indicator for glass-grade products.

Heavy metal limits

When used in agricultural applications, the requirement for limited heavy metal content is an important quality control item.

What are the uses of industrial-grade Boric acid?

Industrial-grade boric acid, due to its electron-deficient structure, has wide applications in glass, ceramics, agriculture, and other fields, including glass network formation, fluxing, flame retardancy, and trace element nutrition.

1.Glass and fiberglass industry (core application)

Boric acid is an important raw material in the glass industry. About half of the world’s boron consumption is used in the production of glass fiber and specialty glass. It is both a flux (lowering melting temperature and saving fuel) and a network forger (improving the heat resistance, transparency and mechanical strength of glass), and is used in the production of glass fiber, heat-resistant glass, optical glass and electronic glass.

2.Ceramic and Enamel Glazes

Boric acid is used as a flux and network former in ceramic glazes and enamels. It helps to lower the sintering temperature, reduce the viscosity and surface tension, and improve the refractive index and mechanical strength. It can also substitute for glazes containing lead and is an important raw material for the ceramics industry.

3. Fire retardants and wood preservatives

Boric acid is used as a flame retardant for cellulose materials (wood, paper, cotton fabrics) that forms a glassy protective layer when heated to insulate against heat and oxygen. It is also used as a wood preservative to prevent insect infestation and mold and is widely used in wood structure construction and wood product treatment.

4. Boron fertilizer for agriculture (micronutrient fertilizer)

Boron is an essential microelement for plants, and boric acid is an important raw material for boron fertilizer. It is used to supplement boron for boron-deficient soil (such as rapeseed that blooms but does not bear fruit, fruit trees that drop flowers and fruits, etc.), and helps to improve crop yield and quality.

5. Pesticides and domestic use (indirect contact)

Boric acid is a common component of home insecticides like roach baits. It is a stomach poison and has low toxicity to non-target organisms. It could be in the baits we use to get rid of cockroaches in our homes.

6. Disinfection and preservation (expanded applications)

Boric acid is used in external disinfectants and antiseptics, such as boric acid lotion and boric acid ointment, which care for the skin and mucous membranes by virtue of its mild antibacterial properties.

7.Other Applications

With the development of new materials and new energy sources, the application scope of industrial-grade boric acid continues to expand, such as corrosion inhibitors of metalworking fluids, fluxes, esterification reaction catalysts, electroplating additives, etc.

Summarize

Boric acid (H3BO3, CAS No. 10043-35-3) is a white crystalline powder with a melting point of approximately 170.9℃. As an electron-deficient Lewis acid, it can complex with polyhydroxy compounds and act as a network forger and flux in glass melts. It is the most widely used boron compound in the glass industry and agriculture. In daily life, we encounter it through heat-resistant glass and fiberglass products, ceramic tile glazes, household insecticides, fruits and vegetables, and wood flame retardant treatments. In industry, industrial-grade boric acid is widely used in glass and fiberglass, ceramic enamel glazes, flame retardants and wood preservatives, agricultural boron fertilizers, disinfection and preservation, etc., serving as a multifunctional basic raw material connecting “boron chemistry” with “glass, ceramics, and agriculture”.