Inorganic pigments used in the construction industry
Core Performance Characteristics
The core performance of inorganic pigments stems from their chemical nature as metal oxides or salts, which endows them with some common and highly stable properties:
Excellent weather resistance and lightfastness: This is the most prominent advantage of inorganic pigments. They are extremely resistant to sunlight (especially ultraviolet radiation) and the effects of the natural environment, and are not prone to fading or chalking, making them ideal for long-term outdoor use.
Excellent thermal stability: Most inorganic pigments can withstand high-temperature processing without discoloration or decomposition, exhibiting stability in plastic injection molding, high-temperature coatings, and ceramic firing.
Strong hiding power: Due to their typically high refractive index, inorganic pigments can effectively cover the color of the substrate, requiring only a very thin coating to achieve ideal coverage.
Good chemical stability: They are generally resistant to acids, alkalis, and solvents, and are insoluble in water and common organic media, making colored products more durable.
Relatively weaker color performance: The colors are not as vibrant as organic pigments, the color spectrum is not as complete, and the tinting strength (i.e., the ability to produce intense colors with a small amount of pigment) is also relatively low.
High-Performance and Environmentally Friendly Inorganic Pigments
Besides the traditional pigments mentioned above, there is another class of pigments with superior performance, representing the future direction of development:
Composite Inorganic Pigments (CICPs):
Performance: Formed by calcination at temperatures above 800°C, possessing exceptional weather resistance (up to 15 years or more), temperature resistance (up to 800°C), and chemical stability.
Advantages: Environmentally friendly and non-toxic (although containing metals, they are locked in an inert crystalline structure, safe for human use), with superior color vibrancy compared to traditional inorganic pigments, comparable to some organic pigments.
Disadvantages: High cost, and relatively low tinting strength.
Applications: Used in high-end fields such as ultra-durable fluorocarbon coatings, coil coatings (requiring weather resistance of over 15 years), high-temperature engineering plastics, and high-performance ceramic inks.
Environmentally Friendly Inorganic Pigments:
Direction: Includes new pigments synthesized directly using non-toxic elements such as titanium, bismuth, and copper, or those using coating technology to fix harmful elements (e.g., coated cadmium red).
Features: While maintaining performance, it meets stringent environmental regulations and represents a trend to replace traditional lead- and cadmium-containing pigments and some organic pigments.
Main Members: From Ancient Minerals to Modern Synthetics
The inorganic pigment family includes both ancient members originating from the earth and modern mainstays born in laboratories.
Natural Mineral Pigments: These are the earliest pigments used by humankind, derived directly from natural minerals or soil, such as laterite, ochre, and malachite. They are typically darker in color but inexpensive and are still used in painting and other fields today.
Synthetic Inorganic Pigments: Manufactured artificially through chemical methods, these are currently the mainstay of applications. They overcome some of the shortcomings of natural pigments, offering a wide variety and more stable performance. Let's look at some common examples:
White: Titanium Dioxide (Titanium Dioxide), Excellent whiteness, hiding power, and tinting strength; currently the most widely used white pigment, extensively used in coatings, plastics, and paper.
Black: Carbon Black, Not only an important black pigment, but also significantly improves the strength of rubber when added, making it a key component of automobile tires.
Red: Iron oxide red is the most common red pigment. It has strong hiding power, is inexpensive, and also has anti-rust properties, making it widely used in construction, floor paints, and anti-rust primers.
Yellow: Lead chromium yellow has a bright color and strong hiding power. It was once the most produced yellow pigment, but due to its lead content, it is being replaced by more environmentally friendly varieties.
Blue: Ultramarine has a bright and vibrant color, is heat-resistant and alkali-resistant, and is often used for coloring paintings, rubber, and plastics.
In general, choosing inorganic pigments usually involves a trade-off between stability and durability and color performance. If organic pigments are the "artists" pursuing the ultimate color, then inorganic pigments are the "powerful" ones that can withstand the test of time and remain steadfast in their role.