CN114081848A - Composition for skin care and application thereof - Google Patents

Abstract

The invention provides a composition for skin care, which comprises a solvent, a compound organic acid accounting for 0.20-8.0% of the total mass and an alkaline neutralizing agent; wherein the solvent is selected from one of water, ethanol or liquid polyhydric alcohol or two or more mixed in any proportion; the compound organic acid consists of small molecular organic acid with the molecular weight not higher than 500 and macromolecular organic acid with the molecular weight of 10-500 ten thousand, and the mass ratio of the small molecular organic acid to the macromolecular organic acid is 10:1 to 1: 10; the pH value of the composition is 3.0-6.0. The invention also provides a preparation method of the composition and application of the composition in preparing cosmetics. The composition provided by the invention can quickly restore the pH range of skin and maintain the weak acid environment of the skin for a long time, thereby improving the barrier function of the skin and being beneficial to maintaining the balance of microbial flora of the skin.

Description

Composition for skin care and application thereof

Technical Field

The invention relates to the technical field of cosmetics, in particular to a weakly acidic composition for skin care and a preparation method and application thereof.

Background

Human skin secretes oil and fat, which is converted from triglyceride to fatty acid by the decomposition of microorganisms on the skin surface to form a layer of oil film (small-molecule fatty acid and incompletely decomposed glyceride), thereby providing a weak acid environment to the healthy skin of an adult (Schade, h.and marchinoni, a.der saururemantel der haut. klin. wochenschr.7, 12-14 192 (8)). The oil film is important for protecting the moisture content of the skin, reducing the evaporation speed of moisture and improving the barrier function of the skin. The weak acid environment of the skin is furthermore crucial for maintaining the homeostasis of the skin's own micro flora. The skin micro-ecology interacts with the skin to form a skin health barrier against infection by foreign microorganisms, such as bacteria, viruses and fungi. Imbalance in skin micro-ecology can easily cause various skin health problems and even psychological problems, such as atopic dermatitis, acne and abnormal body odor. The stable skin acid environment is an important biochemical environment for the primary skin microecological balance and is important for maintaining and maintaining the skin microecological balance. For example, the literature reports that Staphylococcus epidermidis (S.epidermidis), which is a resident microorganism on the skin, is more easily propagated in the acidic environment of the human body, while Staphylococcus aureus (S.aureus), which is a foreign pathogenic bacterium, is more easily propagated in the higher pH environment (pH7) (H.members, S.Piessens, A.Bloom, H.Pronk and P.Finkel, International Journal of Cosmetic Science,2006,28, 359. 370 national skin surface pH is on average low 5, while skin surface for residual flow). Therefore, the maintenance of the acidic environment of the skin of the human body is beneficial to the balance and stability of the resident flora of the skin, and can resist the colonization and invasion of external microorganisms and maintain the health of the skin.

With the development of modern life, more and more products are used for face/body cleaning and nursing, the skin is cleaned more and more frequently, and the weak acid environment of the skin is damaged because the acid film of the skin can be cleaned after cleaning and nursing, and the skin can be recovered in a certain time. Long-term frequent cleansing care is more likely to cause various skin problems such as skin sensitivity, dryness, itching, and even acne, pimple and the like in some special parts such as face, and may also develop and deteriorate into acne, which are related to the destruction of the lipid membrane on the skin surface and the reduction of the barrier function of the skin of a human body caused by the imbalance of the skin microecology.

Some skin care products are often seen in the market to be advertised as weak acid products, and most of the time after the weak acid products are added/combined with water-soluble small molecular acid (such as citric acid), and then the pH value of the products is adjusted by alkaline substances such as sodium hydroxide and the like, so that the pH value of the products is weak acid, and the effect of maintaining the acidic environment of the skin is achieved. Although the small molecule acid/salt can rapidly and effectively reduce and restore the pH value of the skin surface and restore the weak acid environment of the skin, the characteristic that the small molecule acid easily penetrates the skin also causes the small molecule acid/salt to have certain stripping corrosivity on the skin and easily causes the skin tolerance problem. If the macromolecular acid is used for adjusting the pH environment of the skin, the macromolecular acid is slow in dissolving and releasing hydrogen ions, so that a larger using amount is needed when the macromolecular acid is used alone. And a large amount of macromolecular acid easily causes the product viscosity to be too high, the dispersibility is poor, and in addition, a layer of obvious film is easily formed on the surface of the skin after the product containing a large amount of macromolecular acid is dried, so the use experience is very poor.

The patent application with the application number of TW20030135487 discloses a skin external agent, and provides a technical scheme that a small molecular organic acid is mixed with a nonionic polymer, and the nonionic polymer is used as a thickening agent, so that the problem that the skin external agent is easily drained and dispersed by skin oil and fat and cannot be uniformly coated when being coated on skin is solved. And further specifically discloses that the organic acid is a small molecule organic acid, the molecular weight is less than 500, the pKa is less than 5, and 99% of the molecules remain in the form of R-COOH acid under use conditions to achieve a low pH; while the lower molecular weight nonionic polymer is limited to 2000-50000 to achieve a moderate thickening effect.

Chinese patent application No. 2007800019330 discloses a skin cosmetic comprising the following components (a), (B) and (C) satisfying the condition (D), (a) β -alanyl-L-histidine and/or a salt thereof; (B) a thickener containing a microgel obtained by dissolving a water-soluble ethylenically unsaturated monomer in a dispersion phase in a composition comprising an organic solvent or an oil component as a dispersion medium and water as a dispersion phase, and performing radical polymerization in the dispersion phase; (C) inorganic and/or organic acids; (D) the skin cosmetic has a pH of 5.0 or more and less than 8.0 at 25 deg.C. The scheme uses a special micro-oil bead water dispersion system as a special thickening system to ensure that the skin feel is optimal and not sticky, and utilizes inorganic acid or organic acid (simple acid) to adjust the final pH value of the product to ensure that the activity and the efficacy of the carnosine are optimal. However, the scheme only solves the problems of dispersion and active efficacy of skin care ingredients, and does not solve the technical problem of how to effectively maintain stable pH value of the skin. Therefore, how to maintain the weak acid environment of the skin more effectively and continuously is still a problem to be solved.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a composition of macromolecular organic acid (molecular weight is 50-500 ten thousand) and small molecular organic acid (molecular weight is less than 500) which can be used in skin care products, and the composition can effectively repair and maintain the pH value of skin. The skin care product containing the composition can also rapidly adjust the pH of the skin and maintain the pH value of the healthy state of the skin for a long time.

A composition for skin care comprises solvent, compound organic acid 0.20-8.0% of total mass, and alkaline neutralizer; wherein the solvent is selected from one of water, ethanol or liquid polyhydric alcohol or two or more mixed in any proportion; the compound organic acid consists of small molecular organic acid with the molecular weight not higher than 500Da and macromolecular organic acid with the molecular weight of 10-500 ten thousand Da, and the mass ratio of the small molecular organic acid to the macromolecular organic acid is 10: 2-50; the pH value of the composition is 3.0-6.0.

In one embodiment according to the present invention, the molecular weight of the small organic acid is selected from one of a mono-hydroxy acid (AHA), a poly-hydroxy acid (PHA), or a bio-acid, or two or more thereof mixed in any ratio.

In one embodiment according to the present invention, the small molecule organic acid is selected from one of glycolic acid, oxalic citric acid, salicylic acid, lactic acid, fatty acid, malic acid, tartaric acid, mandelic acid (mandelic acid), benzilic acid (benzilic acid), gluconolactone (glucolactone), glucoheptonolactone (glucoheptonolactone), gluconic acid, lactobionic acid (lactobionic acid), maltobionic acid (maltobionic acid), small molecule hyaluronic acid, or two or more mixed in any ratio.

In one embodiment according to the present invention, the molecular weight of the macromolecular organic acid is from 20 to 200 million Da, preferably from 30 to 150 million Da.

In one embodiment according to the present invention, the macromolecular organic acid is a 1% by mass solution prepared with a macromolecular polymer as a solute, and the pH may be 2.0-6.0, the macromolecular polymer is selected from one of polyacrylic acid, polymethacrylic acid, pectin, hyaluronic acid, polylactic acid and carboxymethyl cellulose or derivatives thereof, or two or more thereof mixed in any ratio; wherein the derivative is selected from halides with different degrees of substitution, esters, or copolymers formed by polymerization with other small molecule compounds.

In one embodiment according to the present invention, the macromolecular organic acid is pectic acid having a molecular weight of 20 to 200 ten thousand.

In one embodiment according to the invention, the pH of the composition is from 3.5 to 5.8, preferably from 4.0 to 5.6.

The invention also provides a preparation method of the composition, which comprises the following steps:

1) weighing a proper amount of micromolecular organic acid with the molecular weight not higher than 500, and directly dispersing and dissolving the micromolecular organic acid into a proper amount of water to obtain micromolecular acid solution;

2) weighing a proper amount of macromolecular organic acid with the molecular weight of 10-500 ten thousand, and uniformly dispersing the macromolecular organic acid in a polyhydric alcohol solvent to obtain a macromolecular organic acid solution; the polyalcohol solvent is one selected from glycerol, propylene glycol, butanediol or pentanediol, or a composite solvent formed by uniformly mixing two or more of the glycerol, the propylene glycol, the butanediol or the pentanediol in any ratio;

3) slowly adding the uniformly dispersed macromolecular organic acid solution into hot water with the temperature of 80-85 ℃, and stirring for 20-30min under heat preservation;

4) adding small molecular acid solution, stirring, cooling to 30-40 deg.C, and adding appropriate amount of alkaline neutralizer to adjust pH to 3.0-6.0; wherein, the dosage (w/w) of the acid in the composition is 0.20-8.0 percent in parts by mass, and the ratio of the small molecular organic acid to the large molecular organic acid is 1:5 to 5: 1. Preferred small molecule organic acids: more preferably between 1:4 and 4:1 of the macromolecular organic acid;

preferably, the macromolecular organic acid has a molecular weight of from 20 to 200 million Da, more preferably from 30 to 150 million Da.

The invention further provides the application of the composition in preparing cosmetics.

In another aspect of the present invention, there is provided a cosmetic composition comprising the above composition.

The technical scheme of the invention has the following beneficial effects:

the composition provided by the invention can quickly modify and correct disturbed weak acidic environment of the skin and can stably maintain the weak acidic environment of the skin for a long time. Meanwhile, the composition provided by the invention is mild and non-irritant to skin, improves the barrier function of the skin, improves the skin state and maintains the skin health state. According to the composition provided by the invention, the small molecular organic acid and the macromolecular organic acid are compounded, and the small molecular acid is utilized to provide the speed and the mass equivalent efficiency for rapidly releasing the hydrogen radical ions (the mass equivalent efficiency of the hydrogen radical ions is larger than the mass number of the hydrogen radical ions/the mass number of the small molecular organic acid molecules, the mass equivalent efficiency of the hydrogen radical ions is lower; the macromolecular organic acid forms a layer of uniform film on the surface of the skin, can slowly release hydrogen ions, and can maintain and provide a weak acid environment for the skin for a long time. The skin care product containing the composition can keep the pH of the skin between 4 and 6 for a long time after being coated on the skin, effectively maintain the weak acid environment of the skin, and is beneficial to maintaining the self-microecological balance of the skin and resisting the invasion of foreign microorganisms, thereby being beneficial to strengthening the barrier function of the skin and ensuring the improvement of the health of the skin.

Drawings

FIG. 1 is a graph showing the results of a stability test of pH adjustment time of a solution in an example of the present invention;

FIG. 2 is a graph of the results of a skin pH maintenance experiment in an example of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the experimental materials and instruments involved in the present invention are commercially available.

The preparation method comprises the following steps:

1) weighing a proper amount of micromolecular organic acid with the molecular weight not higher than 500, and directly dispersing and dissolving the micromolecular organic acid into a proper amount of water to obtain micromolecular acid solution.

2) Weighing a proper amount of macromolecular organic acid with the molecular weight of 10-500 ten thousand, and uniformly dispersing the macromolecular organic acid in one or more of glycerol, propylene glycol, butanediol, pentanediol and the like or polyol solvent mixed in any proportion to obtain a macromolecular organic acid polyol mixture.

3) Slowly adding the uniformly dispersed macromolecular acid mixture into hot water with the temperature of 80-85 ℃, and stirring for 20-30min under heat preservation.

4) Adding small molecular acid solution, stirring, cooling to 30-40 deg.C, and adding appropriate amount of alkaline neutralizer to adjust pH to 3.0-6.0.

Wherein, the amount of the acid in the composition is 0.20-8.0% by weight, wherein the ratio of the micromolecular organic acid to the macromolecular acid is 1: 5-5: 1. Preferably, the ratio of small molecule organic acid: macromolecular organic acid is 1:4 to 4: 1; more preferably between 1:3 and 3: 1.

Preferably, the macromolecular organic acid has a molecular weight of from 10 to 150 million Da, preferably from 20 to 200 million Da, more preferably from 30 to 150 million Da.

Example 1 comparison of the properties of compositions prepared at different ratios:

1. preparation steps

1) Weighing appropriate amount of glycerol and propylene glycol, slowly adding weighed macromolecular organic acid (pectic acid or/and polyacrylic acid), and uniformly dispersing.

2) Weighing double distilled water (D.I. Water) accounting for 20% of the total mass of the mixture, heating in a water bath to 80-85 ℃, adding the macromolecular acid mixture, and stirring for 20-25 minutes to ensure that the mixture becomes completely clear and transparent;

2, weighing double distilled water (D.I.Water) accounting for 50 percent of the total mass of the mixture, adding small molecular organic acid (glycolic acid and/or citric acid), and uniformly stirring;

3) adding the micromolecular acid solution into the clear and transparent macromolecular acid solution, uniformly stirring, and cooling to 30-40 ℃;

4) dropwise adding a 5% sodium hydroxide solution, and measuring the pH value of the mixed solution until the pH value is set;

5) adding the amount of the double distilled water (D.I.Water) left after calculation, uniformly mixing, and measuring the final pH value and the product viscosity;

2. the proportions of the samples and the results are shown in table 1:

TABLE 1

And (4) conclusion: the fluid wall-hanging effect of samples 2, 3 and 4 shows that the paint has good adhesion and coating properties, and is more suitable for preparing cosmetics.

Example 2 sample preparation and skin irritation test:

1. experimental methods

1) The pH was prepared and measured as described in example 1,

2) the age of 3 subjects is 25-35 years, the left and right forearms are washed with warm water for 5 minutes, gently rubbed and patted dry with paper;

3) at the place where the forearm is about 6-8 cm away from the wrist, each 0.5 cm defines a circle with a diameter of 1 cm, 2 rows (longitudinal direction) in total and 3 in each row;

4) after 15 minutes, starting to coat specified samples at specified positions, wherein each sample is coated by 2.00g, then covering with a round plastic rubber cover, and fixing with a medical adhesive tape;

5) after 30 minutes, carefully remove the glue cap and wipe off the remaining liquid with a paper towel;

6) the skin is observed and the subject is asked for a skin irritation sensation.

2. The specific sample formulation and experimental results are shown in Table 2

TABLE 2

And (4) conclusion: samples 10 and 11 were the least irritating in use, while sample 10 was more coated than sample 11.

Example 3 solution pH adjustment test

1. Experiment raw materials:

lactic acid (Anhui ZhongLiang Biochemical Glatt lactic acid Co., Ltd., reagent grade, 100%)

Hydroxyglycolic acid (Shanghai Dai Chuang chemical science and technology Co., Ltd., reagent grade, 100%)

Sodium hydroxide (Suzhou Fulaite Biotech Co., Ltd., reagent grade, 100%), pectic acid (CP Kelco)

Glycerol (food grade 100% Fengyi oil science & technology (Shanghai)

2. An experimental instrument:

sardolis Sartorius pH meter (pH meter)

Mettler TOLEDO precision balance (balance)

3. The experimental steps are as follows:

1) preparing NaOH solution: preparing 1.00% NaOH solution, and diluting 100 times to 0.01% NaOH solution. The 0.01% NaOH solution was further diluted 100-fold to a concentration of 0.0001%. The final diluted lye pH was measured.

2) A1.20% glycolic acid solution (containing 10.00% glycerol) was prepared. Diluted 100 times to 0.012% hydroxy ethanolic acid solution.

3) 100.00g of the final diluted base solution was taken and gradually added dropwise to a diluted glycolic acid solution (0.012%) to pH 6.00 (+/-0.10).

4) The pH and the amount of glycolic acid solution used were recorded.

5) Preparing 1.20% macromolecular pectic acid solution:

weighing appropriate amount of macromolecular pectic acid powder, adding into glycerol, and stirring. Weighing appropriate amount of distilled water, heating to 80-85 deg.C in water bath, and slowly adding pectic acid/glycerol mixture into water. Keeping the temperature and stirring for 20-30 minutes.

6) Repeating the steps 3) to 4), and recording the dosage of the macromolecular pectic acid;

7) adding a proper amount of micromolecular glycolic acid solution into the macromolecular pectic acid solution, uniformly stirring to obtain a mixed acid solution with a proper proportion, and recording the using amount of micromolecular glycolic acid/macromolecular pectic acid composite acid;

8) experiments 2) -7) were repeated and the respective amounts of lactic acid, macropectic acid, and lactic acid and macropectic acid complex solution were recorded as shown in tables 3 and 4.

TABLE 3

Initial solution concentration	Initial NaOH solution pH	pH of the solution after dropwise addition of acid	Amount of acid solution used (g)
				1.00% glycolic acid	7.96	6.03	0.78
1.20% macromolecular pectic acid	7.85	5.91	6.65
				1.00% glycolic acid + 1.2% macromolecular pectic acid	7.96	6.00	0.87

TABLE 4

Initial solution concentration	Initial NaOH solution pH	pH of the solution after dropwise addition of acid	Amount of acid solution used (g)
				1.20% lactic acid	8.09	6.00	1.05
1.20% macromolecular pectic acid	7.88	6.05	3.38
				1.20% lactic acid + 1.2% macromolecular pectic acid	8.13	6.02	0.71

Experiments show that the use of the composite acid can effectively reduce the use amount of the acid, particularly the use amount of the macromolecular acid, thereby being beneficial to reducing skin irritation, reducing the sticky feeling of products containing the composition and improving the experience of consumers.

Example 4 solution pH adjustment time stability test

The glycolic acid, the macromolecular pectic acid and the glycolic acid/pectic acid complex acid in example 1 were respectively added dropwise to the NaOH solution, and the pH change of the solution was detected at 0,15min,30min,1hr,2hr and 4 hr.

The results are shown in figure 1, and the pectic acid solution itself, the small molecule acid and the large molecule acid can better buffer the pH value of the buffer solution after being compounded, and the pH value of the solution can be better kept in the initial pH range within 4 hours.

Example 5 skin pH maintenance experiment

1. The experimental method comprises the following steps:

1) the testers select and mark 3 parts from the inner side of any forearm (left or right), test the initial pH value,

2) moistening skin with Deionized water (Deionized water), smearing 1.0g of natural bath lotion (market product), and manually soaking for 1 min;

3) cleaning with 30ml of deionized water, and measuring the PH;

4) patting the paper towel to dry, and measuring the pH;

5) applying skin care product containing complex acid, completely absorbing, measuring pH, recording as 0, and measuring skin pH within 15min,30min,1hr,2hr, and 4 hr.

2. Results

The results are shown in fig. 2, where the pH of the skin was significantly increased relative to the skin washed with body wash and without any skin care treatment after rinsing with water, and the skin did not return to its original pH after 4 hours. If a skin care agent containing only a small-molecular organic acid is used, the pH of the skin itself disturbed by the cleansing, can be effectively lowered, but the skin pH is still slightly higher than the initial skin value and does not return to the initial pH value until after 4 hours. Skin care ingredients using macromolecular pectic acid restored the skin to the initial skin pH almost immediately upon application and maintained the initial skin pH for a stable maintenance period of 30 minutes.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A composition for skin care is characterized by comprising a solvent, a compound organic acid accounting for 0.20-8.0% of the total mass and an alkaline neutralizing agent; wherein the solvent is selected from one of water, ethanol or liquid polyhydric alcohol or two or more mixed in any proportion; the compound organic acid consists of small molecular organic acid with the molecular weight not higher than 500Da and macromolecular organic acid with the molecular weight of 10-500 ten thousand Da, and the mass ratio of the small molecular organic acid to the macromolecular organic acid is 1:5 to 5: 1; the pH value of the composition is 3.0-6.0.

2. The composition of claim 1, wherein the small organic acid has a molecular weight selected from one of a mono-hydroxy acid (AHA), a poly-hydroxy acid (PHA), or a bio-acid, or two or more thereof mixed in any ratio.

3. The composition of claim 1, wherein the small organic acid is selected from one of glycolic acid, fatty acids, oxalic acid, citric acid, salicylic acid, lactic acid, malic acid, tartaric acid, mandelic acid (mandelic acid), benzilic acid (benzilic acid), gluconolactone (glucolactone), glucoheptonolactone (glucoheptonolactone), gluconic acid, lactobionic acid (lactobionic acid), maltobionic acid (maltobionic acid), or small hyaluronic acid, or two or more thereof mixed in any ratio.

4. The composition of claim 1, wherein the macromolecular organic acid has a molecular weight of 20 to 200 million Da, preferably 30 to 150 million Da; more preferably 20 to 200 million Da pectic acid.

5. The composition according to claim 1, wherein the macromolecular organic acid is a 1% by mass aqueous solution with a pH of 2.0-6.0 prepared as a solute of a macromolecular polymer selected from the group consisting of polyacrylic acid, polymethacrylic acid, pectic acid, hyaluronic acid, polylactic acid and carboxymethylcellulose or one of their derivatives, or two or more thereof mixed in any ratio; the derivative of the macromolecular acid is selected from halides with different degrees of substitution, esters or copolymers formed by polymerizing with other small molecular compounds.

6. The composition according to claim 1, wherein the composition has a pH of 3.5 to 5.8, preferably a pH of 4.0 to 5.6.

7. The composition of claim 1, wherein the mass ratio of the small organic acid to the large acid is 10: 1-1: 10; preferably 5: 1-1:5.

8. A method of preparing a composition as claimed in any one of claims 1 to 7, comprising:

1) weighing a proper amount of micromolecular organic acid with the molecular weight not higher than 500, and directly dispersing and dissolving the micromolecular organic acid into a proper amount of water to obtain micromolecular acid solution;

2) weighing a proper amount of macromolecular organic acid with the molecular weight of 10-500 ten thousand, and uniformly dispersing the macromolecular organic acid in a polyalcohol solvent to obtain a macromolecular acid mixture; the polyalcohol solvent is one selected from glycerol, propylene glycol, butanediol or pentanediol, or a composite solvent formed by uniformly mixing two or more of the glycerol, the propylene glycol, the butanediol or the pentanediol in any ratio;

3) slowly adding the uniformly dispersed macromolecular acid mixture into hot water with the temperature of 80-85 ℃, and stirring for 20-30min under heat preservation;

4) cooling the solution to 30-40 ℃, adding a small molecular acid solution, uniformly stirring, and then adding a proper amount of an alkaline neutralizing agent to adjust the pH value to 3.0-6.0; wherein, the amount of the acid in the composition is 0.20-8.0% by weight, wherein the ratio of the micromolecular organic acid to the macromolecular organic acid is 10:1 to 1: 10; preferred small molecule organic acids: the ratio of the macromolecular organic acid is between 1:5 and 5: 1.

Preferably, the macromolecular organic acid has a molecular weight of from 20 to 200 million Da, more preferably from 30 to 150 million Da.

9. Use of a composition according to any one of claims 1 to 7 for the preparation of a cosmetic product.

10. A cosmetic product comprising the composition according to any one of claims 1 to 7.

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