Hydrogenated castor oil

Description

Hydrogenated castor oil is a waxy compound obtained by the hydrogenation of refined castor oil. It is a hard product with a high melting point. It is almost odourless and tasteless. HCO is supplied in flakes and powder. Hydrogenated castor oil is cream to white coloured.
appearance white to creamish flakes or powder
melting point °C 83 - 87
colour Gardner max. 3
colour (on 1” Lovibond) max 20 yellow / max.2 red
acid value mg KOH/g max. 5
iodine value g/100g max. 5
hydroxyl value 155 - 165
saponification value mg KOH/g 180 - 190

Chemical properties

Hydrogenated castor oil occurs as a fine, almost white or pale yellow powder or flakes. The PhEur 6.0 describes hydrogenated castor oil as the oil obtained by hydrogenation of virgin castor oil. It consists mainly of the triglyceride of 12-hydroxystearic acid.

Hydrogenated castor oil — also called HCO or castor wax — is a hard, white, opaque vegetable wax. Its resistance to moisture makes it useful in many coatings, greases, cosmetics, polishes and similar applications.
The wax is created by hydrogenating pure liquid castor oil, which is obtained from castor beans. The oil is heated under extreme pressure using a nickel catalyst during the hydrogenation process. Afterward, the hydrogen creates saturated molecules of castor wax, which gives the oil a higher melting point that allows it to remain solid at room temperature. After hydrogenation, the oil becomes hard and brittle to the touch.

The Uses of Hydrogenated castor oil

1. greases: Lithium- and Calcium hydroxystearates dispersed in base oil to make multipurpose greases having higher dropping points, hardness, better rust-proofing, lubricity and durability than stearates.
2. other lubricants: metal drawing lubes, PVC lubricants for PVC pipes, profiles, sheets, pharma tabletting, metal powders, ceramics.
3. cosmetics: HCO of different melting points used in lipsticks, deodorant and antiperspirant sticks, cosmetic creams.
4. slip additive in inks, paints, plastics (PE).
5. dispersing agent in plastic colour master batches, carbon papers, inks.
6. flow control and dispersing additive in powder coatings, hot-melt adhesives and sealants.
7. shoe polishing, furniture polishing creams.

Production Methods

Hydrogenated castor oil is prepared by the hydrogenation of castor oil using a catalyst.

Pharmaceutical Applications

Hydrogenated castor oil is a hard wax with a high melting point used in oral and topical pharmaceutical formulations. In topical formulations, hydrogenated castor oil is used to provide stiffness to creams and emulsions. In oral formulations, hydrogenated castor oil is used to prepare sustained-release tablet and capsule preparations; the hydrogenated castor oil may be used as a coat or to form a solid matrix.
Hydrogenated castor oil is additionally used to lubricate the die walls of tablet presses; and is similarly used as a lubricant in food processing.
Hydrogenated castor oil is also used in cosmetics.

Safety

Hydrogenated castor oil is used in oral and topical pharmaceutical formulations and is generally regarded as an essentially nontoxic and nonirritant material.
Acute oral toxicity studies in animals have shown that hydrogenated castor oil is a relatively nontoxic material. Irritation tests with rabbits show that hydrogenated castor oil causes mild, transient irritation to the eye.
LD₅₀ (rat, oral): >10 g/kg

storage

Hydrogenated castor oil is stable at temperatures up to 1508℃. Clear, stable, chloroform solutions containing up to 15% w/v of hydrogenated castor oil may be produced. Hydrogenated castor oil may also be dissolved at temperatures greater than 908℃ in polar solvents and mixtures of aromatic and polar solvents, although the hydrogenated castor oil precipitates out on cooling below 908℃. Hydrogenated castor oil should be stored in a well-closed container in a cool, dry place.

Incompatibilities

Hydrogenated castor oil is compatible with most natural vegetable and animal waxes.

Regulatory Status

Accepted in the USA as an indirect food additive. Included in the FDA Inactive Ingredients Database (oral capsules, tablets, and sublingual tablets).
Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.