Hydrogenated Castor Oil Stearate, also known as Octadecanoic acid, esters with hydrogenated castor oil, is a versatile ingredient used in various cosmetic and personal care products for its skin conditioning and viscosity controlling properties.

Chemical Composition and Structure

Hydrogenated Castor Oil Stearate is an ester formed by the reaction of hydrogenated castor oil with stearic acid (octadecanoic acid). This combination creates a stable and effective ingredient that provides both emollient and thickening benefits. The chemical structure consists of the long-chain fatty acids from castor oil, which have been saturated (hydrogenated) and then esterified with stearic acid.

Physical Properties

Hydrogenated Castor Oil Stearate typically appears as a white to off-white solid or wax. It is soluble in oils and dispersible in water, making it suitable for various formulations. It provides a smooth, creamy texture to products and helps stabilize emulsions.

Chemical Industrial Synthesis Process

• Preparation of reagents. The main raw materials include hydrogenated castor oil and stearic acid.
• Esterification. The hydrogenated castor oil is mixed with stearic acid in a reactor. An acidic catalyst, such as sulfuric acid (H₂SO₄) or p-toluenesulfonic acid, is added to facilitate the esterification reaction.
• Heating. The mixture is heated to a controlled temperature (approximately 180-220°C) under continuous stirring to allow the formation of Hydrogenated Castor Oil Stearate. Water is produced as a by-product during the reaction.
• Removal of water. The water produced during the reaction is removed through azeotropic distillation or by using a drying agent, such as anhydrous sodium sulfate.
• Cooling. The reaction mixture is cooled to room temperature.
• Neutralization. The mixture is neutralized with a sodium hydroxide (NaOH) solution to remove excess acidic catalyst.
• Washing. The produced ester is washed with deionized water to remove any soluble impurities.
• Drying. The washed ester is dried using a drying agent, such as anhydrous sodium sulfate, to remove residual moisture.
• Filtration. The dried solution is filtered to remove any solid impurities.
• Distillation. The Hydrogenated Castor Oil Stearate is further purified by vacuum distillation to obtain a pure product.
• Quality control. The Hydrogenated Castor Oil Stearate undergoes rigorous quality testing to ensure it meets standards for purity and safety. These tests include chemical analysis and spectroscopy.

What it is used for and where

Hydrogenated Castor Oil Stearate is highly valued for its multifunctional properties. By providing both skin conditioning and viscosity controlling benefits, it enhances the performance of a wide range of skincare and personal care products. Manufacturers can incorporate this ingredient to achieve a smooth, stable, and effective formulation.

Cosmetics - INCI Functions

Skin Conditioning: Hydrogenated Castor Oil Stearate is widely used in skincare products for its skin conditioning properties. It helps to soften and smooth the skin, enhancing its overall feel and appearance. It forms a protective barrier on the skin, preventing moisture loss and keeping the skin hydrated.

Viscosity Controlling: This ingredient acts as a viscosity controller in cosmetic formulations. It helps to thicken and stabilize products, ensuring a consistent texture and application. It is commonly used in creams, lotions, and other emulsion-based products to achieve the desired consistency.

Safety

Hydrogenated Castor Oil Stearate is generally considered safe for use in cosmetic and personal care products. It is non-irritating and suitable for all skin types, including sensitive skin. As it is derived from natural sources and is biodegradable, it poses minimal risk to the environment when disposed of properly. However, it is important to use it within the recommended guidelines to ensure product safety and efficacy.

References__________________________________________________________________________

Bährle-Rapp, M., & Bährle-Rapp, M. (2007). Hydrogenated Castor Oil Stearate. Springer Lexikon Kosmetik und Körperpflege, 264-264.