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A Preliminary Study on Inorganic Powder in Cosmetics

Apr 09, 2022

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A Preliminary Study on Inorganic Powder in Cosmetics

Human beings have been pursuing cosmetic products to beautify themselves since ancient times. Cosmetics is a general term for products for the purpose of makeup, including washing cosmetics for cleaning the human body; basic cosmetics for adjusting skin moisture and oil, maintaining and moisturizing the skin to maintain skin health; beauty cosmetics for retouching the face; beautifying and protecting hair and nails cosmetics and fragrance products. There are various types of cosmetics. From the perspective of their ingredients, cosmetics are made by mixing different raw materials through different processes.

Behind the dazzling cosmetics is a huge chemical system. Using modern chemical technology, people can easily and quickly produce enough cosmetics to meet the needs of consumers. In the production of cosmetics, inorganic powders are mainly used as colorants and fillers in color cosmetics.

Inorganic Pigments in Cosmetics

The application of colorants in cosmetics is mainly evaluated from two aspects of cosmetology and psychology, and it has not yet been found to have any benefits to the human body; on the contrary, excessive or long-term use will also cause various cumulative damages. Except for some natural and inert colorants, most synthetic colorants are harmful to human body.

Cosmetic colorants (or pigments) can be divided into three categories according to their sources: synthetic pigments, inorganic pigments and natural animal and plant pigments. Synthetic pigments can be divided into dyes, lakes and pigments according to their solubility. Dyes are those that can be dissolved in water or oil and alcohol, and are divided into water-soluble and oil-soluble dyes according to different dissolution media. Lakes are dyes that are insoluble in water. Or pigments, which are mainly formed by the precipitation of water-soluble acid dyes through metal salts or the adsorption of these metal salts on water-resistant pigments; pigments are a coloring powder that is insoluble in water, oil and other solvents, and has Better tinting power, hiding power and anti-dissolution, widely used in lipstick, rouge and other beauty cosmetics. Inorganic pigments mainly include: metal and alloy powders, oxide and hydroxide pigments and other inorganic pigments.

Metal and Alloy Powders

According to my country's current GB7916-87 regulations, there are three kinds of metal and alloy powders in cosmetic temporary colorants: aluminum powder, copper powder and bronze powder. Among them, aluminum powder shall not be used in oral and lip cosmetics; copper powder and bronze powder can be used in general cosmetics. The characteristics of this type of cosmetics are mainly metallic luster. In a transparent medium, its luster and color have a "two-color effect" with the change of light angle and line of sight. With the development of pearlescent pigments, such pigments gradually fade out of cosmetic applications.

aluminum powder

The aluminum powder is silver-gray powder with a relative density of 2.55 and a melting point of 685°C. Aluminum powder for pigment generally refers to aluminum powder with scaly particle structure and coated with fatty acid film on the surface. Quality index of aluminum powder for cosmetics (FDA.1984): particle size, 100% pass 200 mesh sieve, 95% pass 325 mesh sieve; Hg≤1mg/kg, As≤3mg/kg, Pb≤20mg/kg, Al content Quality score ≥99%.

copper powder

The copper powder is a red powder with a relative density of 8.92 and a melting point of 1084.5°C. Copper powder for pigment generally refers to copper powder with a scaly structure and coated with a fatty acid film on the surface. Quality index of copper powder for cosmetics (FDA, 1984): copper content mass fraction (calculated as Ca) ≥ 95%, particle size ≤ 45μm number ≥ 95%, fatty acid or oleic acid mass fraction ≤ 5%, cadmium ≤15mg/kg, lead≤20mg/kg, arsenic≤3mg/kg, Hg≤1mg/kg.

bronze powder

Bronze powder is an alloy powder of copper and zinc with small amounts of aluminum and tin. Bronze powder for pigment generally has a scaly particle structure and is coated with a fatty acid film on the surface. Standard bronze powder can be divided into three types: purple gold powder (90%Cu-10%Zn), which is golden red; light purple gold powder (85% Cu-15%Zn), golden; light gold powder (70%Cu-30%Zn), greenish-gold. Its quality index (FDA, 1984) (in terms of mass fraction): copper content ≥ 70%, ≤ 95%; zinc content ≤ 30%; aluminum content ≤ 0.5%; tin content ≤ 0.5%; cadmium less than or equal to 15mg/kg; lead≤20mg/kg; arsenic≤3mg m/kg; Hg≤1mg/kg; the number of particles with particle size≤45μm≥95%.

Oxide and Hydroxide Pigments

Synthetic iron oxide pigments are important cosmetic pigments, including iron oxide red, iron oxide yellow, iron oxide black, and iron oxide brown. They are all oxides of iron, but their composition and structure belong to different types of minerals. The hue and physical properties of iron oxide pigments prepared by different preparation methods are quite different. Chromium oxide green and chrome hydroxide green are used in the formulation of some cosmetic pigments, which are the standard reference for cosmetics (FDA, 1984).

Titanium dioxide

Titanium dioxide can not only absorb ultraviolet rays, but also reflect and scatter ultraviolet rays, and can also transmit visible light. Cosmetic titanium dioxide can adjust and control the properties and effects of coated nano titanium dioxide particles by choosing different coating methods.

Zinc oxide

Zinc oxide and titanium dioxide are two important and widely used physical sunscreens that both absorb and scatter UV light. At the same time, zinc oxide has antibacterial properties, and its antibacterial mechanism comes from two aspects: Zn 2+ and Ag + , Cu 2+ belong to heavy metal ions, which can combine with sulfhydryl groups on proteins in bacteria and viruses, thereby inhibiting their activity; zinc oxide Under the irradiation of ultraviolet rays, hole-electron pairs will be generated, and the active holes and electrons will migrate to the surface of the particles, and the water or hydroxyl groups adsorbed on the surface will be converted into hydroxyl radicals, thereby killing most bacteria and viruses. Cosmetic zinc oxide requires full-band UV protection, excellent dispersibility and transparency, safe and non-irritating, and good photostability.

Other inorganic pigments

Ultramarine blue (Na 6 Al 6 Si 6 O 24 S 4 )

Ultramarine blue is a complex of sodium thioaluminate, mostly bright blue powder, insoluble in water, and similar in structure to zeolite. Changes in the aluminum and sulfur elements it contains have a certain effect on the color tone. The particle size of ultramarine blue pigments also affects its properties. The base type ultramarine blue and its mixture have hydrophilic surface characteristics, and have good light resistance, heat resistance, solvent resistance and alkali resistance, but their acid resistance is poor. Ultramarine pigments in cosmetics are often used in products such as eye creams, eyebrow pencils and soaps.

Manganese Violet

Manganese violet is a chemical that is a purple powder with low tinting strength and hiding power. It is mainly used for cosmetic preparation of eye cream, eyeliner, etc. It can provide the required reddish purple for cosmetics, and can also be used in other fields that require reddish purple. In addition, manganese violet can be used as a toner in plastics and coatings to reduce yellowing in white plastics and white coatings. A small amount of manganese violet is also used as a paint.

Nowadays, the safety of cosmetics has attracted the attention of the governments of various countries. The governments of various countries have set up special institutions to formulate and revise relevant regulations through modern testing methods and scientific toxicological evaluation. my country, the United States and the European Union have restrictions on the dosage of some colorants in cosmetics; Japan has no regulations on the amount of colorants allowed in cosmetics, but there are dosage levels accepted by the general market.

Inorganic powder filler

The electrodeless powder fillers commonly used in cosmetics are: silica, diatomaceous earth, layered silicate powder filler, precipitated calcium carbonate, phosphate, aluminum hydroxide, etc., among which layered silicate powder is filled The agents are mostly kaolin, bentonite, talc, mica powder.

silica

There are many types of silica, and the main application in the cosmetic industry is precipitated silica. This type of silica is colorless, transparent and bright crystalline and amorphous powder. Chemically inert, insoluble in water and acids (except hydrofluoric acid), soluble in concentrated lye. It is stable in the pH range of cosmetic use. Precipitated silica is divided into five grades according to its structure grade: ultra-high structure VHS, high structure HS, medium structure MS, low structure LS, ultra low structure VLS, according to its particle size, particle size distribution and pore volume can be used for in different cosmetics.

Silica is mainly used in perfume powder, perfume adsorbent (carrier) of pressed powder cosmetics, friction agent of fluoride toothpaste and transparent toothpaste, friction agent of scrub and scrub cleanser.

diatomite

The chemical composition of diatomaceous earth is hydrated silica SiO 2 ·nH 2 O. Diatomite has a porous structure, high oil absorption, low bulk density and high adhesion. As a cheap powder filler, diatomite is mainly used in various powders and pressed powders, as well as in facial masks.

Layered silicate powder filler

Layered silicate powder fillers are an important class of powder fillers, and they are widely used in powder-containing collision varieties. In this type of layered silicate, a silicon oxide layer is present. Common layered silicate powder fillers are mostly kaolin, bentonite, talc and mica. Mainly used in the manufacture of fragrant powder, powder cake, rouge, wet powder, facial mask and as a cosmetic thickener and other additives.

Precipitated calcium carbonate

Precipitated Calcium Carbonate, also known as Light Calcium Carbonate, is a white very fine light powder that is soluble in acid. According to different production methods, the structure of precipitated calcium carbonate can be divided into calcite type, aragonite type or a mixture of the two. In the field of cosmetics, precipitated calcium carbonate is mainly used in the manufacture of fragrant powder, pressed powder, rouge, talcum powder, etc. Due to its good absorption, it is often used as a fragrance mixture in the manufacture of powder cosmetics, and can also be used as a friction agent for toothpaste.

Phosphate

Phosphate inorganic powder additives used in the field of cosmetics are mainly three kinds of calcium hydrogen phosphate, dicalcium phosphate and calcium pyrophosphate, which are often used in toothpaste as an abrasive or a stabilizer for fluoride toothpaste.

The production of cosmetics is inseparable from the ratio of various chemical raw materials. Among them, inorganic powders play a crucial role. Choose your favorite cosmetics from the cosmetics.