Cosmetic material containing crystalline superfine silk powder

Details Cosmetic material containing crystalline superfine silk powder Cosmetic material containing crystalline superfine silk powder

2001-02-02

2004-04-13

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Cosmetic, antiperspirant, dentifrice

C424S489000, C424S070100, C424S400000

Reexamination Certificate

active

06719985

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a cosmetic material that contains crystalline superfine silk powder below 3 &mgr;m in particle diameter and is suitable for application to the skin.
BACKGROUND TECHNOLOGY
Cosmetics include a variety of powders, for example, clay minerals (in the field of cosmetics, powdered clay minerals are referred to as “extender pigments”) and/or color materials (for example, dyes and pigments).
Clay minerals include mainly talc, mica, kaolin, and sericite.
These powdered extender powders have been used for a long time because of their coating power, spreadability, adhesion, and the like, which are necessary for cosmetic materials.
Moreover, the extender powder is contained in the powder cosmetic material as a main ingredient. Taking talc as an example, which is a typical extender powder, it is contained in as high a proportion as 90% or more in talcum powder or baby powder, 80% in face rouge (compact type), around 50 to 80% in the facial powder or solid-type facial powder, and around 45% in eye shadow and cake-type foundations. Accordingly, the quality of the property of the extender powder becomes a decisive crucial factor in determining the quality of cosmetics.
Moreover, color materials for coloring cosmetic materials is divided into pigments and dyes: the pigment can be adsorbed by means of other substances whereas the dye can be adsorbed by means of other substances.
As a pigment, natural minerals such as tuff loam or loess, or powder color materials (inorganic pigments) of metallic oxides such as iron oxide, titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, zirconium oxide, and chromium oxide have been conventionally used.
In the case of using cosmetics that contain these extender powders or color materials, particularly, a powder cosmetic material having a high content of an extender powder, complaints include drawbacks of unsuitability to the skin due to the powdery property.
Such an attempt as to make the content of the extender powder as low as possible to overcome this drawback would present a problem in that the feeling of touch would be degraded and solidified substances would become readily breakable because of the lack of balance between the powders.
Furthermore, the extender powder including talc, mica, kaolin, and sericite has coating power, spreadability, adhesion and the like to the skin surface. However, it absorbs moisture or lipids from the skin and causes the skin to seize due to dehydration, lipid removal, drying or the like. Its spreadability and adhesion cannot be said to be satisfactory.
On the other hand, coloring materials of natural minerals such as tuff loam or loess, and metallic oxide powders such as iron oxide, titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, zirconium oxide, and chromium oxide are useful as raw materials. However, they have no function of absorption and desorption of moisture, and no permeability of moisture, so that they cannot be said to be a material suitable for skin since they would prevent respiration of the skin when brought into intimate contact with the skin.
Moreover, the color of cosmetic materials is prepared with difficulty by one type of color material and thus several types of color materials have been mixed for preparation.
In order to solve these extender powder or color material drawbacks, a technique has been suggested for use in coating the surface of powders such as talc, kaolin, titanium oxide, zinc oxide or the like with reproduced fibroin that has excellent affinity to skin and is a material suitable for a living body with good absorption and desorption of moisture. (Refer to Japanese Patent Publication No. Sho 28-250, Japanese Patent Publication No. Sho 57-11577, Japanese Laid-Open Patent Publication No. Hei 9-25217, Japanese Laid-Open Patent Publication No. Hei 9-309816, and Japanese Laid-Open Patent Publication No. Hei 9-302261).
In contrast to the development of a technique for such cosmetics which employs powders with color materials predominantly composed of an extender powder or a metallic oxide, which are predominantly composed of these clay minerals, coated with reproduced fibroin, research has been carried out for a long time in attempts to use a silk substance singly as a cosmetic powder.
For example, the invention according to Japanese Patent Publication No. Sho 26-4947 employs a silk powder as a cosmetic base material, the silk powder being obtained by spraying a reproduced fibroin aqueous solution in the atmosphere.
However, a reproduced silk powder, such as the silk powder according to the aforementioned invention, which is obtained from an aqueous solution into which silk yarn is dissolved has low crystallinity, that is, the reproduced silk powder is an amorphous silk powder.
The amorphous silk is soluble in water. Accordingly, when such an amorphous silk powder is adhered to skin moist with perspiration, the amorphous silk powder absorbs the perspiration to partly dissolve and become viscous.
When this is touched by hand, the silk powder lumps (particles) to become rough to the touch and provides a bad appearance.
Skin moist with perspiration occurs daily, such as after playing sports, taking a bath, during the rainy season or in sultry summer weather. In cases where powder cosmetic materials are used under this skin condition, it can be naturally understood that powder cosmetic materials containing amorphous silk powder are not suitable.
Accordingly, amorphous silk powder can be used when it is in a liquid state, that is, it can be used as a cosmetic material such as a lotion and can be used in a solid state (powder) with difficulty. In the case of using amorphous silk as in a powder, its content is around 5% or less.
Thereafter, such a technique was developed as attempting to expand the range of applications of the silk powder as a cosmetic raw material by increasing the crystallinity of the amorphous reproduced silk powder, that is, by decreasing the degree of solubility in water. An example includes a fine reformed silk powder and the method for manufacturing thereof (Japanese Laid-Open Patent Publication No. Hei 4-337331), the fine reformed silk powder being provided with the crystallinity of reproduced silk powder increased up to half that of silk yarn.
Other methods include one in which a silk powder obtained by powdering the silk yarn mechanically or physically is used as a cosmetic raw material.
For example, Japanese Patent Publication No. Sho 27-3650 provides a fine silk powder for use as a cosmetic material that is obtained through treatment of the silk yarn with an alkali aqueous solution, neutralization, washing in water, dehydration, drying, and powdering, with the diameter of the particles small enough to pass through a mesh of No.300 (10 &mgr;m in particle diameter).
Moreover, a method is suggested in which the silk yarn is heated with saturated vapor or heated vapor, then the silk is released to expand under low pressure, and then dried to be powdered in order to obtain a silk powder 30 to 50 &mgr;m in diameter (refer to Japanese Patent Publication No. Sho 61-36840 and Japanese Patent Publication No. Sho 63-51160). Another method is suggested in which the silk yarn is dissolved in a certain aqueous solution, then the aqueous solution is dialyzed to obtain a silk fibroin aqueous solution which is in turn brought into contact with a coagulating liquid, and then the precipitated fine particulate silk fibroin is dried to obtain a silk powder of 6.5 to 19 &mgr;m in diameter (refer to Japanese Laid-Open Patent Publication No. Hei 4-88027). Another method is suggested in which the silk fibroin is powdered in a multi-stage process where dry and mechanical powdering means are employed, and is subjected to &bgr; treatment at least in one stage of the multi-stage process or after the multi-stage process to obtain a superfine silk fibroin powder 3.25 &mgr;m in average particle diameter. (Refer to Japanese Laid-Open Patent Publication No. Hei 6-339924.)
The present applicants have already suggested a method in which a sil

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