Discover the key varieties of iron oxide pigments, their extensive applications, and historical significance. Learn about the manufacturing processes involved.

Iron Oxide

Iron oxide pigments are among the most widely utilized color pigments globally. They come in primary colors such as yellow (FeOOH), black (Fe3O4), and red (Fe2O3), and can be blended to produce hues of orange, beige, and brown.

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The History Of Iron Oxide

Iron Oxides have been used since prehistoric times, primarily for their red shades. Early humans used them to create cave paintings, leaving evidence of their existence and depicting animal figures to aid in hunting. Such artworks have been discovered in locations like the Saubia Mountains in Germany, Lascaux in France, and Altamira in Spain, dating back to between 40,000 and 10,000 BC. These colors originated from iron oxide-rich mineral clays.

Iron Oxides later appeared in Neolithic ceramics, Renaissance and Impressionist paintings, and early city bricks. Although natural iron oxides are still in use, synthetic variants have become more prevalent due to their superior pigment performance. Their widespread utility stems from their natural shades and excellent chemical, physical, and technical properties, making them indispensable in many fields.

Key Attributes

• Range: Iron Oxides
• Sub-range: Red Iron Oxides (GO series)
• Color Index: Pigment Red 101/C.I. 77491 (Iron Oxide Red)
• Basic Chemical Composition: Fe2O3
• Dispersibility: Excellent
• Hiding Power/Opacity: Excellent
• Heat Fastness: 800°C, 5 min
• Light Fastness: Excellent
• Weather Fastness: Excellent
• Acid Fastness: Excellent
• Alkali Fastness: Excellent
• Cement Compatibility: Excellent
• Solvent Fastness: Excellent
• Metamerism: None
• Applications: Food Contact Packaging / Toys / General Packaging / Electric and Electronic Equipment / Automotive / Construction / Fertilizers / Plant Protection Products / Industrial Uses / Artist Supply and Hobby Preparations

Manufacturing Processes

The Laux Process

Initially used to produce aniline from nitrobenzene, the Laux process, discovered by Dr. Laux in 1925, can also generate black, yellow, and red iron oxide pigments under specific chemical conditions. The key reactions are:

• Black: \( 9 Fe + 4 C_6H_5NO_2 + 4 H_2O \rightarrow 3 Fe_3O_4 + 4 C_6H_5NH_2 \)
• Yellow: \( 2 Fe + C_6H_5NO_2 + 2 H_2O \rightarrow 2 FeO(OH) + C_6H_5NH_2 \)
• Red: \( 2 Fe_3O_4 + \frac{1}{2} O_2 \rightarrow 3 Fe_2O_3 \)

The Precipitation Process

This method involves oxidizing iron sulfate in an alkaline environment using atmospheric oxygen to produce yellow iron oxide pigment. This reaction requires a yellow nucleus pigment for high-quality output:

• Reaction: \( 2 FeSO_4 + 4 NaOH + \frac{1}{2} O_2 \rightarrow 2 FeO(OH) + 2 Na_2SO_4 + H_2O \)

The Penniman Process

In the Penniman process, iron scrap is oxidized in a sulfate acid medium with atmospheric oxygen to produce yellow iron oxide. A yellow pigment nucleus is required for high-quality results:

• Reaction: \( 2 Fe + \frac{1}{2} O_2 + 3 H_2O \rightarrow 2 FeO(OH) + 2 H_2 \)

The company stands as one of the premier iron oxide pigment for industry suppliers. We provide comprehensive services to meet your requirements, supported by our highly-specialized staff to assist in product selection.

Eco-Friendly

Synthetic red, yellow, orange, brown, and black iron oxides are non-toxic and manufactured using 60% post-industrial recycled content.

Applications

Iron oxide pigments are versatile, affordable, and durable, making them suitable for numerous industries and products.

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