JP3700940B2 - Method for producing porous sheet for skin care - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing a porous sheet for skin care. The present invention relates in particular feel resistance and a manufacturing method excellent skin care porous sheet to water retention.
[0002]
[Prior art]
In recent years, packing with a hydrophilic sheet containing a lotion has been actively performed for the purpose of giving moisture to the skin or improving rough skin. In addition, in order to recover skin that has been damaged by tanning or after tanning outdoors with an esthetic treatment or the like, a lotion having an anti-inflammatory effect is included in a hydrophilic sheet and packed.
As the sheet for impregnating the skin lotion, pulp processed into a sheet or cellulose non-woven fabric is generally used. As an emphasis on feel, there is a porous sheet obtained by foaming bovine-derived collagen.
Sheets based on pulp and cellulose are inexpensive, but their merchantability is inferior due to the stiff feel. On the other hand, materials made of mammals as a raw material tend to be inferior in merchantability, such as mad cow disease.
[0003]
In recent years, porous sheets for skin care based on chitosan having a high affinity for skin have been studied.
In the aqueous solvent system, chitosan is dissolved in an acidic aqueous solution and cross-linked to insolubilize water, or the pH is returned to near neutrality to insolubilize chitosan, and then the porous body of chitosan is produced by removing water The method to do is common. However, as the moisture evaporates during the drying process, the solid content shrinks, and the appearance is poor and the merchantability is poor. As a drying method, the freeze-drying method has a slight effect of preventing shrinkage compared to the hot-air drying method, but a porous body satisfying the appearance has not been obtained.
In order to prevent shrinkage at the time of drying, it is common to add a polyhydric alcohol such as glycerin as a plasticizer. However, after drying, the resulting porous material is sticky and feels bad. Addition of cellulose fiber as a reinforcing material is effective in preventing shrinkage, but there is a disadvantage that the good feeling peculiar to chitosan is impaired, and a porous body that is satisfactory in appearance and excellent in touch is not obtained is the current situation.
[0004]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to improve the drawbacks of the above-mentioned conventional porous sheet for skin care based on chitosan, that is, it has uniform air bubbles and is particularly satisfactory in appearance, feel and it is to provide a method for producing superior skin care porous sheet to water retention.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have added a solid or pasty emulsifier at room temperature to the porous sheet composition based on chitosan, It has been found that the above problems can be solved.
That is, the present invention is as follows.
(1) Dilute hydrochloric acid or an organic acid is added to a suspension obtained by dispersing chitosan in an aqueous solution of an emulsifier that is solid or pasty at room temperature and is nonionic and has an HLB value of 10 or more, and the pH is adjusted to 5. Porous for skin care characterized by adjusting to 0-6.0 and then lyophilizing and then slicing to a desired thickness to make a sheet, or lyophilizing after making a sheet of desired thickness Method for manufacturing a sheet.
(2) after pH adjustment of the suspension prepared by dispersing chitosan claim 1 for skin care porous sheet manufacturing method as set forth, characterized in that the addition of aliphatic diepoxy compound as a crosslinking agent.
[0006]
As described above, the porous sheet for skin care of the present invention and the production method thereof contain chitosan having a high affinity for the skin as a main component, and are solid or pasty at room temperature and soluble in hot water. By containing a suitable emulsifier, when chitosan is dissolved in an acidic aqueous solution, preferably crosslinked and insolubilized in water and then frozen, water freezes and the emulsifier also hardens. Thereafter, the emulsifier cured when removing moisture by vacuum drying acts as a reinforcing agent for preventing the shrinkage of chitosan, and a porous body having an excellent appearance can be obtained.
Since the emulsifier is solid or pasty at room temperature, it is possible to obtain a porous sheet having no sticky feel in a dry state. Moreover, it becomes unnecessary to add a fibrous substance such as cellulose as a reinforcing material, and a porous sheet for skin care excellent in feel and water retention and a method for producing the same can be provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the porous sheet for skin care of the present invention and the production method thereof will be described in detail.
As described above, the characteristic features of the skin care porous sheet and the method for producing the same in the present invention are based on chitosan.
The chitosan used in the present invention is not particularly limited to raw materials and the like, but is obtained by deacetylation by heating chitin with concentrated alkali, for example, and is deacetylated measured by a colloid titration method using a polyvinyl potassium sulfate aqueous solution. A degree of 80% or more is preferred. The molecular weight of this chitosan is not particularly limited as long as it is not extremely low molecular weight, but usually has a weight average molecular weight of 5 × 10 ⁴ to 1 × 10 ⁶ .
The chitosan content in the skin care porous sheet is preferably in the range of 50 to 90% by weight.
If the amount is less than 50% by weight, the strength of the porous sheet is lowered and the use is hindered. If the amount exceeds 90% by weight, the porous sheet is hard at the time of drying and is not suitable for commercial use. .
[0008]
The porous sheet for skin care according to the present invention and the method for producing the same, when chitosan is dispersed and dissolved in an acidic aqueous solution, preferably cross-linked and insolubilized, and then frozen by containing at least an emulsifier in chitosan. As the water freezes, the emulsifier also hardens. Thereafter, the emulsifier cured when removing moisture by vacuum drying acts as a reinforcing agent for preventing the shrinkage of chitosan, and a porous body having an excellent appearance can be obtained.
The emulsifier used in the present invention is an emulsifier that is solid or pasty at room temperature and is soluble in hot water. Furthermore, it is preferable to use a nonionic material having an HLB value of 10 or more.
When the melting temperature of the emulsifier is low, a sticky feeling is obtained when it is applied to the skin. Therefore, the melting temperature is preferably 20 ° C. or higher, more preferably 30 ° C. or higher. Since it is solid or pasty at room temperature, it is possible to obtain a porous sheet without a sticky feel in a dry state.
The emulsifier used in the present invention is preferably a nonionic one having little influence on the skin, and preferably has an HLB value of 10 or more, more preferably 12 or more.
If the HLB value is low, the water absorption of the dried porous sheet is lowered, and it takes time to include the skin lotion, which is unpopular. Furthermore, since the solubility in water becomes poor as the HLB value decreases, it becomes difficult to obtain a uniform suspension by dispersing chitosan during production.
Specific examples of the emulsifier used in the present invention are not limited to ether type, ester type and the like. For example, polyethylene glycol lauryl ether, polyethylene glycol stearyl ether, polyethylene glycol oleyl ether, sucrose fatty acid ester, polyethylene glycol stearic acid Examples include esters.
The amount of the emulsifier added is not particularly limited, but it is generally preferably 5 to 50% by weight based on the chitosan weight.
[0009]
In addition, it is also possible to add active ingredients for the skin such as glycyrrhizin, sodium hyaluronate, sodium chondroitin sulfate.
[0010]
In the method for producing a porous sheet for skin care of the present invention, dilute hydrochloric acid, or an acid (inorganic acid or organic acid) added to swell and dissolve chitosan in water so that no odor remains after vacuum drying As the organic acid having no odor remaining, citric acid, gluconic acid, succinic acid, lactic acid, fumaric acid, malic acid and the like are used.
[0011]
The chitosan suspension is adjusted to pH by using the above acid aqueous solution in a suspension in which chitosan is dispersed in an aqueous solution in which a solid or pasty emulsifier is heated to a temperature at which the emulsifier is soluble at room temperature. The pH is adjusted to 5.0 to 6.0, preferably pH 5.0 to 5.5.
When the pH of the chitosan suspension is less than 5.0, the obtained porous body is strongly irritating to the skin, and when it exceeds 6.0, the chitosan is not sufficiently dissolved and the cross-linking reaction cannot be performed. It is. The above pH range is suitable for the reaction between the amino group of chitosan and the crosslinking agent, and is the same range as the skin.
[0012]
The concentration of chitosan in the chitosan dispersion suspension is not particularly limited, but a preferable concentration is in the range of 1 to 10% by weight.
If it is less than 1% by weight, the strength of the resulting porous body is weak and unsuitable for practical use. If it exceeds 10% by weight, the viscosity when dissolved in an acid aqueous solution is high, and the crosslinking reaction cannot be made uniform. Both are unsuitable.
[0013]
In the porous sheet for skin care and the method for producing the same according to the present invention, the crosslinking method for obtaining the hydrogelated product from the chitosan / emulsifier solution dissolved in water described above has the safety to the living body as well as the odor. In order to increase this, an aliphatic diepoxy compound is added as a highly safe crosslinking agent for the living body, and the mixture is reacted under the conditions of pH, temperature, and time according to the crosslinking agent to perform a gelling treatment.
Examples of the aliphatic diepoxy compound include polyethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, hexanediol diglycidyl ether, and the like. Most preferred is ethylene glycol diglycidyl ether.
Although the addition amount of a crosslinking agent does not have limitation in particular, Generally, it is preferable that the glycidyl group of a diepoxy compound is 1-20 mol% with respect to the amino group of chitosan.
[0014]
Next, as described above, the porous sheet for skin care of the present invention contains a chitosan / emulsifier solution dissolved in water, preferably a cross-linking agent, and the solution is prepared by adjusting the pH and temperature conditions. By performing freeze-drying on the gelled hydrogel product, a porous body in which the ice crystal portion at the time of freezing has air bubbles can be obtained.
The porous body for skin care having uniform and dense cells, which is a preferred embodiment of the porous sheet for skin care of the present invention, is rapidly frozen in the above lyophilization under the condition of −50 ° C. or lower and then vacuum dried. It is a feature to perform.
Examples of the method of rapidly freezing at −50 ° C. or less include, for example, direct contact with dry ice, immersion in dry ice / methanol or liquid nitrogen, collision of cold air at −50 ° C. or less, or dynamic magnetic field Among them, there may be mentioned a method of freezing all at once in a supercooled state under a temperature of −50 ° C. or less while giving weak vibration and suppressing ice crystallization.
In order to obtain a porous sheet for skin care having a sheet-like uniform cell with excellent merchantability, the sheet-like water-containing gelled product is rapidly frozen under a condition of −50 ° C. or less, or a block Porous material obtained by ordinary freeze-drying method by rapidly drying a sheet-like hydrated gelled product under a condition of −50 ° C. or lower and then vacuum-drying the sheet-like material sliced to a desired thickness It is possible to obtain a porous sheet-like elastic body that is superior in appearance and touch compared to the body and is gentle to the skin, and has a high level of merchandise for cosmetics and uniform cells for skin care. it can.
[0015]
Further, at the same time as freezing at a time in the supercooled state, the freezing time is preferably within 1 hour, more preferably within 30 minutes.
When it is longer than 1 hour, ice crystals grow, and after vacuum drying, coarse bubbles are formed, which is inappropriate.
The degree of vacuum at the time of vacuum drying needs to be a vacuum of 60 Pa or less so that ice crystals do not melt.
[0016]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to these examples.
[Example 1]
Crab-derived chitosan having an average particle size of 100 μm and a deacetylation rate of 85%, 10 g of polyethylene glycol stearyl ether which is a solid emulsifier at room temperature (Brij78, HLB = 15.3, melting point 44-46 ° C .: Sigma-Aldrich Japan Co., Ltd.) 1 g, 1.5 g of glycerin as a plasticizer at the time of drying was added and dispersed well in 500 g of distilled water, and the mixture was well stirred and mixed for 1 hour on a 60 ° C. hot water bath. Next, 1N hydrochloric acid was gradually added to adjust the pH to 5.3, and then ethylene glycol diglycidyl ether (epoxy equivalent = 113) was added as a calculated value so that the crosslinking degree was 5% with respect to chitosan. After rapidly stirring and mixing, degassing was performed with a centrifugal separator at 100 G × 10 minutes. The degassed mixture was carefully poured into a stainless steel container having a depth of 120 mm × 160 mm × 30 mm so as not to entrain air bubbles. The vessel was heated on a hot water bath at 60 ° C. for 3 hours, and then allowed to cool at room temperature to obtain an epoxy-crosslinked hydrous gelled product of chitosan.
[0017]
The stainless steel container containing the obtained hydrogel was placed on a copper plate laid on dry ice, the copper plate was also placed on the top surface of the container, and rapidly frozen with dry ice on it. The frozen hydrogel was vacuum dried at room temperature for 72 hours using a vacuum dryer to obtain a chitosan porous material having a thickness of approximately 25 mm. The porous sheet obtained by slicing the obtained chitosan porous body to about 1 mm using a cutter knife has an apparent density = 0.03 g / cm ³ , has a water absorption of 15 times its own weight, and has a smooth surface feel. It was excellent in good water retention.
[0018]
[Example 2]
Instead of polyethylene glycol stearyl ether (Brij78, HLB = 15.3, melting point 44-46 ° C .: Sigma-Aldrich Japan Co., Ltd.) in Example 1, polyethylene glycol stearyl ether (Brij76, HLB = 12.4, melting point) 37-39 degreeC: The same operation as Example 1 was performed except having used Sigma-Aldrich Japan Co., Ltd.). The obtained chitosan porous sheet was similar to Example 1 and had excellent water retention with a smooth and smooth surface.
[0019]
[Comparative Example 1]
The same operation as in Example 1 except that 1 g of cellulose powder (KC Flock, W-100: manufactured by Nippon Paper Industries Co., Ltd.) for improving sheet strength was used instead of polyethylene glycol stearyl ether in Example 1. Went. The obtained chitosan porous sheet was inferior in merchantability as compared with Examples 1 and 2, having a feel of cellulose powder.
[0020]
[Comparative Example 2]
The same operation as in Example 1 was performed except that 2.5 g of glycerin was used instead of polyethylene glycol stearyl ether in Example 1. Since the chitosan porous material contracted during vacuum drying and became an irregular shape, it was difficult to slice using a cutter knife.
[0021]
[Comparative Example 3]
Example 1 except that 1 g of sucrose stearate (DK ester F50, HLB = 6, melting point 58 ° C .: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of polyethylene glycol stearyl ether in Example 1. The same operation was performed. The dispersion with chitosan was poor and even when heated, a uniform dispersion was not obtained, and the following operation could not be performed.
[0022]
【The invention's effect】
As described above, the porous sheet for skin care and the method for producing the same of the present invention contains chitosan as a main component, and further is an emulsifier which is solid or pasty at room temperature and is soluble in hot water, preferably By containing an emulsifier that is nonionic and has an HLB value of 10 or more, the emulsifier cured when the water-containing gelled product is frozen and then removed by vacuum drying acts as a reinforcing agent that prevents the shrinkage of chitosan. A porous sheet for skin care having excellent feel and water retention, and a method for producing the same, without the need to add a fibrous material such as cellulose as a reinforcing material. Can be provided.

Claims (2)

A dilute hydrochloric acid or organic acid is added to a suspension in which chitosan is dispersed in an aqueous solution of an emulsifier that is solid or pasty at room temperature and is nonionic and has an HLB value of 10 or more. H Skin care, characterized in that, after adjusting to 5.0 to 6.0, lyophilized and then sliced to a desired thickness to make a sheet, or lyophilized after making a sheet of desired thickness For producing a porous sheet for use in an automobile. P of suspension in which chitosan is dispersed H After adjustment, an aliphatic diepoxy compound is added as a cross-linking agent. 1 The manufacturing method of the porous sheet for skin care as described.