Take you to know the "oil" family in cosmetics

Oil is an important raw material of cosmetics, which affects the appearance, skin feeling, efficacy, stability, etc. of cosmetics to a large extent. So, what kinds of oils are commonly used in cosmetics? What role do they play in cosmetics?

Grease and oil

Greases and oils refer to fatty acid glycerides formed by different kinds of fatty acids and glycerols, including glycerol esters (formed by one molecule of glycerol and one molecule of fatty acid), diglycerides and triglycerides. There are many kinds of fatty acids, so there are many kinds of greases and oils. Grease can also be called oil for short, but generally speaking, oil also includes various fatty acids. There are two classifications of grease:

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Under normal temperature, it can be classified into solid oil, liquid oil and semi-solid oil according to the state. (See Table 1)

Table 1 Oil State Classification and Characteristics

According to the source, it can be divided into mineral oil, vegetable oil, animal oil and chemically synthesized oil. (See Table 2)

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Table 2 Source Classification and Characteristics of Oil

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Function of oil in cosmetics

In recent years, driven by the beauty economy, people's demand for skin care has not only stayed at the level of water supplement, but also paid more attention to replenishing the oil needed by the skin to achieve the best water oil balance. Oils are commonly used in skin care, hair care, body care and makeup products. Consumers can choose cosmetics suitable for themselves by identifying the name of oil in the ingredient list of the product.

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Grease has the following eight functions in cosmetics.

First, moisturizing, which is the most basic and important function of oil.

As a skin (lip) moisturizer in the formula oil phase, grease acts like skin lipids, making skin and hair soft, smooth, elastic and shiny. For example, "mineral oil", "jojoba oil" and "isododecane".

Second, barrier function. Solid oil and semi-solid oil form a hydrophobic film on the skin to inhibit the evaporation of skin moisture, prevent skin dryness, and protect the skin from external physical and chemical stimuli.

Third, cleaning effect. According to the principle of similar compatibility, oil can make oily dirt on the skin surface easier to clean. Such as makeup remover products.

Fourth, solvent action. At present, the solvent oils used in cosmetics are more isoparaffins. Alkane raw materials are widely used in cosmetics, ranging from color cosmetics to cream lotion, hand care and hair care products, and all oil products. Isoalkane products are colorless, tasteless, low viscosity, light oil sense, easy biodegradation and other characteristics, with fresh skin, stable properties, and good compatibility with various waxes, organosilicon, and mineral oils.

Fifth, emulsification. As surfactant/emulsifier, oil can emulsify, co emulsify, solubilize and other surfactant functions for water and oil, such as as solvent for pigment, preservative and essence. Representative components include "polysorbate - 60", "PEG-100 stearate", "glycerol stearate", etc.

Sixth, the role of modification. Oil can also play the role of beauty (hair) and modification. For example, "candela wax", "carnauba wax", "isododecane" and "liquid paraffin" in hair wax, and "C13-14 isoalkanes" in elastin.

Seventh, adjust the effect of skin feeling. When designing the formula, cosmetic formulators can use oil with other ingredients to improve the skin feel. For example, a facial massage cream contains "mineral oil" and "isocetane". The combination of mineral oil and alkanes can improve the emulsion skin feeling, make the product more refreshing and reduce the burden on the skin.

Eighth, carrier function (bionic technology). As the carrier of nutrition and conditioning materials, oil is easier to be absorbed by skin. Such as active substance carrier (phospholipid complex, liposome encapsulation technology), etc.

Quality requirements for oils in cosmetics

The physicochemical constants of oils and fats reflect the characteristics and quality of oils and fats. For example, the standard indexes of oils and fats include acid value (acid value)<1; Saponification value: 180~200; Glycerin content 10%; Iodine value: the iodine value of dry oil is above 130; The iodine value of semi dry oil is 100~130; The iodine value of non drying oil is below 100. It is generally required that the aromatic content in the solvent oil is extremely low, and the oil is usually light or colorless; It is also strict with its color and smell.

In addition, the oil ingredients added in cosmetics must be the raw materials in the 2021 Catalogue of Used Cosmetic Raw Materials, and meet the requirements of the Technical Specifications for the Safety of Cosmetics (2015) for their physicochemical, microbial, heavy metal and other indicators.