Pigment White 21 is a chemical compound, a white synthetic dye composed of baryte, the sulphate salt of barium, an alkali metal.
Chemical Name
barium(2+);sulfate
Chemical Composition and Structure
Pigment White 21 is an inorganic compound with the chemical formula BaSO4. It consists of barium (Ba), sulfur (S), and oxygen (O), combined to form barium sulfate. This compound is known for its insolubility in water and high density, making it particularly useful as a pigment and filler.
Physical Properties
This pigment typically appears as a fine white powder. It has a high density, which contributes to its excellent covering power. Pigment White 21 is known for its chemical stability, resistance to light and heat, and non-reactive nature, making it safe for a wide range of applications.
Processo industriale di sintesi chimica
- Preparation of reagents. The main raw materials include sodium sulfate (Na₂SO₄) and barium chloride (BaCl₂).
- Precipitation reaction. The production of Pigment White 21 begins with the reaction between sodium sulfate and barium chloride in an aqueous solution.This reaction forms a precipitate of barium sulfate (BaSO₄).
- Filtration. The resulting suspension is filtered to separate the solid precipitate of barium sulfate from the aqueous solution.
- Washing. The barium sulfate precipitate is washed with deionized water to remove any soluble impurities such as sodium chloride.
- Drying. The washed barium sulfate is dried at controlled temperatures to remove residual moisture and obtain a dry powder.
- Grinding. The dried barium sulfate is ground to obtain a fine and uniform powder. This step may involve the use of ball mills or other grinding machinery.
- Classification. The dried powder is classified to ensure a uniform particle size. This step may involve sieving or the use of air classifiers.
- Stabilization. The Pigment White 21 powder is stabilized to ensure its stability during transportation and storage, preventing aggregation and degradation.
- Quality control. The Pigment White 21 undergoes rigorous quality testing to ensure it meets standards for purity and consistency. These tests include chemical analysis, spectroscopy, and physical tests to determine particle size and rheological properties.
What it is used for and where
This pigment is widely used in various industrial and cosmetic products due to its excellent physical and chemical properties, including high density, stability, and opacity.
Cosmetics
Restricted cosmetic ingredient as IV/122 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Substance or ingredient reported:
Cosmetics - INCI Functions
Colorant. This ingredient has the function of colouring the solution in which it is inserted in a temporary, semi-permanent or permanent manner, either alone or in the presence of the complementary components added for colouring.
Pigment White 21 is used in cosmetic products such as foundations, powders, and eyeshadows for its high opacity and ability to improve the texture of products. It is also used in skincare products due to its non-irritating nature.
Industrial Applications
Pharmaceutical and Medical: Pigment White 21 is used in medical applications, such as contrast agents for X-rays, due to its high density and opacity to X-rays.
Paints and Coatings: In this sector, barium sulfate is used as an extender to improve the coverage and durability of paints. Its stability makes it suitable for exterior and decorative applications.
Plastics and Polymers: Pigment White 21 is employed in the production of plastics and polymers to enhance the strength and color stability of finished products.
Paper: Barium sulfate is used as a filler in paper production, improving gloss, opacity, and overall quality of the paper product.
Safety
Pigment White 21 is generally considered safe for use in consumer products, provided it is handled following proper safety procedures. It is insoluble in water and non-reactive, minimizing environmental risks. However, as with all powdered materials, inhalation should be avoided, and direct contact with skin and eyes minimized
Molecular Formula BaO4S
Molecular Weight 233.39 g/mol
CAS 7727-43-7
UNII 25BB7EKE2E
EC number 231-784-4
MFCD00003455
Synonyms:
CI 77120