JP7212727B1 - Method for producing chitosan derivative - Google Patents

Abstract

Kind Code: A1 A chitosan derivative having a high salt forming rate and excellent emulsifying performance, which enables the preparation of an emulsified composition such as a milky lotion having good stability by finely dispersing various oils in water, and a method for producing the chitosan derivative. I will provide a. The acyl group derived from the acylating agent and the amine-carboxylic acid group derived from the salt forming agent have a weight average molecular weight of 120,000 to 3,000,000 and a degree of deacetylation of 70 to 100. %, and the ratio (A/S) of the ratio (A) of the acyl group introduction to the ratio (S) of the amine-carboxylic acid group introduction is 9 to 70. be. A chitosan derivative is produced by reacting chitosan with an acylating agent and a salt-forming agent in a state in which chitosan having a particle size that can pass through a mesh with an opening of 1 mm is dispersed in a reaction solvent containing an alcoholic solvent. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a chitosan derivative, a method for producing the same, an O/W emulsion composition, and a cosmetic.

Low-molecular-weight surfactants, which are widely used in the fields of cosmetics, foods, and detergents, have high surface activity, but have structures similar to lipid molecules, so they do not cause irritation due to penetration into the skin. are concerned. On the other hand, petroleum-derived polymeric surfactants are difficult to be taken up by the human body and can be said to be relatively safe. tend to be restricted. Therefore, surfactants using polysaccharides derived from natural products as raw materials have been actively developed.

For example, siloxane-modified polysaccharides obtained by grafting organopolysiloxane to polysaccharides are used in film-forming cosmetics used for hair and skin, as well as gas separation membranes, back coating agents for thermal transfer, paints, and the like. It is useful as an ingredient to be blended.

It should be noted that emulsifiers used as raw materials for cosmetics are required to have high molecular weights with low skin permeability. For example, there has been proposed a chitosan derivative, which is obtained by grafting a long-chain fatty acid to chitosan having a molecular weight of about 100,000, and which is blended in cosmetics and the like (Patent Document 1). Further, an alkali metal salt of acylated chitosan having an acylation degree of 80% or more, which can be used in cosmetics and the like, and a method for producing the same have been proposed (Patent Document 2).

JP-A-2000-212203 JP-A-8-157501

However, even if the chitosan derivative proposed in Patent Document 1 is used as an emulsifier, it is not necessarily easy to prepare an emulsified composition such as a milky lotion with excellent stability. In addition, the emulsification performance of the chitosan derivative proposed in Patent Document 2 was not so good. The chitosan derivative proposed in Patent Document 2 has a relatively low salt formation rate due to its high degree of acylation, and is not so good in water solubility. In addition, since it is an alkali metal salt, it cannot be said that the water-solubility in the weakly acidic range, which is important in the field of products that come into contact with the skin, such as cosmetics, is so good. In addition, since it is an amphoteric electrolyte, it may become easy to form an intramolecular complex depending on the pH, making it difficult to prepare emulsified compositions such as milky lotions in some cases.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide an emulsified composition such as a latex having good stability by finely dispersing various oils in water. To provide a chitosan derivative having a high salt-forming rate and excellent emulsifying performance, which enables the preparation of Another object of the present invention is to provide a method for efficiently producing this chitosan derivative, an O/W emulsion composition using this chitosan derivative, and a cosmetic.

That is, according to the present invention, the following chitosan derivative is provided.
[1] The acyl group derived from the acylating agent and the amine-carboxylic acid group derived from the salt forming agent have a weight average molecular weight of 120,000 to 3,000,000 and a deacetylation degree of 70 to 100%. wherein the ratio (S/A) of the introduction rate (S) of the amine-carboxylic acid group to the introduction rate (A) of the acyl group is 9 to 70. .
[2] The chitosan derivative according to [1] above, wherein the acyl group has 7 to 20 carbon atoms.
[3] The chitosan derivative according to [1] or [2], wherein the salt-forming agent is at least one selected from the group consisting of pyrrolidonecarboxylic acid, ascorbic acid, glycolic acid, lactic acid, and acetic acid.
[4] The chitosan derivative according to any one of [1] to [3], which is used as a polymeric surfactant.

Further, according to the present invention, there is provided a method for producing a chitosan derivative shown below.
[5] The method for producing a chitosan derivative according to any one of [1] to [4] above, wherein the chitosan having a particle size that can pass through a mesh with an opening of 1 mm is dispersed in a reaction solvent containing an alcoholic solvent. In this state, the chitosan is reacted with the acylating agent at 55 to 100° C., and then the acylating agent and the salt forming agent are reacted to form the acyl group and the amine-carboxylic acid group on the chitosan. A method for producing a chitosan derivative, comprising introducing.
[6] The method for producing a chitosan derivative according to [5], wherein the alcohol solvent is at least one selected from the group consisting of isopropyl alcohol, normal propyl alcohol, and ethanol.

Further, according to the present invention, the following O/W emulsion composition and cosmetics are provided.
[7] Water, oil, and an emulsifier that disperses the oil in the water in the form of emulsified droplets, wherein the emulsifier is the chitosan derivative according to any one of [1] to [4]. /W type emulsion composition.
[8] The O/W emulsified composition according to [7] above, wherein the median diameter (d ₅₀ ) of the emulsified droplets is 12.0 μm or less.
[9] A cosmetic containing the chitosan derivative according to any one of [1] to [4].

ADVANTAGE OF THE INVENTION According to the present invention, a chitosan derivative having a high salt formation rate and excellent emulsifying performance is provided, which enables the preparation of an emulsified composition such as a milky lotion having good stability by finely dispersing various oils in water. can do. Moreover, according to the present invention, it is possible to provide a method for efficiently producing this chitosan derivative, an O/W emulsion composition using this chitosan derivative, and a cosmetic.

<Chitosan derivative>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. In the chitosan derivative of the present invention, an acyl group derived from an acylating agent and an amine-carboxylic acid group derived from a salt-forming agent are introduced into chitosan. The ratio (S/A) of the introduction rate (S) of the amine-carboxylic acid group to the introduction rate (A) of the acyl group is 9-70. The details of the chitosan derivative of the present invention are described below.

Chitosan is a compound that inherently has cationic properties because it has an amino group, which is a reactive group. The chitosan derivative of the present invention is prepared by reacting an acylating agent and a salt-forming agent (hereinafter collectively referred to as "modifying agents") with chitosan, and converting acyl groups and amine-carboxylic acid groups derived from these modifiers into chitosan. It was formed by introducing Furthermore, by controlling the ratio (S/A) of the introduction rate (S) of the amine-carboxylic acid group to the introduction rate (A) of the acyl group within a specific range, emulsification performance is improved. , excellent emulsifying performance is exhibited when blended in a composition such as a cosmetic. In addition, by controlling the S/A value within a specific range, even oils that are relatively difficult to finely disperse in water (such as silicone oil) can be easily finely dispersed and stabilized. can be prepared.

(chitosan)
Chitosan is a deacetylated product of chitin obtained from crustaceans, filamentous fungi, and insects. there is Chitosan is industrially produced and available in various grades.

The weight average molecular weight of chitosan is preferably 120,000 to 3,000,000, more preferably 150,000 to 3,000,000, and 200,000 to 3,000,000. is particularly preferred. When the weight average molecular weight of chitosan is less than 120,000, the stability of emulsified compositions such as milky lotions prepared using the obtained chitosan derivative as a polymer surfactant (emulsifier) is lowered. On the other hand, if the weight average molecular weight of chitosan exceeds 3,000,000, the viscosity of the solution becomes too high, making it difficult to handle when blended in cosmetics.

The degree of deacetylation of chitosan is 70-100%, preferably 75-99%. If the degree of deacetylation of chitosan is less than 70%, the emulsification performance of the obtained chitosan derivative cannot be improved, and it is difficult to prepare an emulsified composition such as a milky lotion with small emulsified droplets and excellent stability. Can not. The degree of deacetylation of chitosan can be calculated from the titration amount by performing colloidal titration. Specifically, a toluidine blue solution is used as an indicator, and colloidal titration is performed with an aqueous potassium polyvinyl sulfate solution to quantify free amino groups in the chitosan molecule and determine the degree of deacetylation of chitosan. An example of the method for measuring the degree of deacetylation is shown below.

(1) Titration test Chitosan was added to a 0.5% by mass acetic acid aqueous solution so that the chitosan pure concentration was 0.5% by mass, and the chitosan was stirred and dissolved to give 100 g of 0.5% by mass chitosan/0.5% by mass. A 5 mass % acetic acid aqueous solution is prepared. Next, 10 g of this solution and 90 g of ion-exchanged water are stirred and mixed to prepare a 0.05% by mass chitosan solution. Furthermore, 50 mL of ion-exchanged water and about 0.2 mL of toluidine blue solution are added to 10 g of this 0.05% by mass chitosan solution to prepare a sample solution, which is titrated with a polyvinyl potassium sulfate solution (N/400 PVSK). The titration rate is 2 to 5 ml/min, and the point at which the color of the sample solution changes from blue to reddish purple and is maintained for 30 seconds or longer is defined as the end point titration amount. The chitosan pure content means the mass of chitosan in the starting chitosan sample. Specifically, it is the mass of solid content obtained by drying a starting chitosan sample at 105° C. for 2 hours.

(2) Blank Test Instead of the 0.5% by mass chitosan/0.5% by mass acetic acid aqueous solution used in the above titration test, deionized water is used and the same titration test is performed.

(3) Calculation of degree of acetylation X = 1/400 x 161 x f x (VB)/1000
= 0.4025 x f x (VB)/1000
Y=0.5/100-X
X: Amount of free amino groups in chitosan (equivalent to glucosamine residue mass)
Y: Bonded amino group amount in chitosan (equivalent to N-acetylglucosamine residue mass)
f: N/400 PVSK titer V: Titration volume (mL) of sample solution
B: blank titration volume (mL)
Degree of deacetylation (%)
= (free amino group) / {(free amino group) + (bonded amino group)} x 100
=(X/161)/(X/161+Y/203)×100
"161" is the molecular weight of the glucosamine residue, and "203" is the molecular weight of the N-acetylglucosamine residue.

(Acylating agent)
Acylating agents are compounds that react with the reactive functional groups of chitosan, used as modifiers of chitosan. The reactive functional groups of chitosan are mainly amino groups (--NH ₂ ), and hydroxyl groups (--OH) may function as reactive groups depending on the reaction conditions. Acylating agents include fatty acids, fatty acid anhydrides, polyvalent fatty acids, polyvalent fatty acid anhydrides, fatty acid halides, and the like. These acylating agents can be used singly or in combination of two or more. The number of carbon atoms in the acyl group introduced into chitosan by the acylating agent is preferably 7-20, more preferably 8-18. Polyvalent fatty acids and polyvalent fatty acid anhydrides are preferably divalent or trivalent, more preferably divalent. As the acylating agent, fatty acids, fatty acid anhydrides, and fatty acid halides are preferred, fatty acid anhydrides and fatty acid halides are more preferred, and fatty acid anhydrides are particularly preferred.

Specific examples of acylating agents include octanoic anhydride, myristic anhydride, stearic anhydride, oleic anhydride, bis(2-ethylhexanoic) anhydride, stearic acid chloride, myristic acid chloride, myristic acid Bromide and the like can be mentioned. Among them, octanoic anhydride, myristic anhydride, stearic anhydride, and oleic anhydride are preferred.

(salt-forming agent)
The salt-forming agent used as a chitosan modifier reacts with the amino group (--NH ₂ ) among the reactive functional groups of chitosan to form an amine-carboxylic acid group (--NH ₃ ^{+ .--} OOC-R (R is a salt). It is a compound that can form a former residue)). A compound having a carboxy group, that is, an organic acid can be used as the salt-forming agent. Specific examples of salt-forming agents include pyrrolidonecarboxylic acid, ascorbic acid, glycolic acid, lactic acid, acetic acid, glycine, succinic acid, glutamic acid and the like. Among them, pyrrolidonecarboxylic acid, ascorbic acid, glycolic acid, lactic acid, and acetic acid are preferred. These salt-forming agents can be used singly or in combination of two or more.

(Acyl group introduction rate (A) and amine-carboxylic acid base introduction rate (S))
The introduction ratio (A) of acyl groups derived from the acylating agent is preferably 0.008 to 0.1, more preferably 0.01 to 0.09, and 0.012 to 0.08. It is particularly preferred to have If the acyl group introduction rate (A) is less than 0.008, emulsification may become difficult. On the other hand, if the acyl group introduction rate (A) is more than 0.1, the turbidity generated during dissolution may become strong, and it may become difficult to dissolve in an aqueous medium in the weakly acidic region. It tends to be somewhat difficult to incorporate into products that come into contact with

The introduction ratio (S) of the amine-carboxylic acid group derived from the salt-forming agent is preferably from 0.55 to 0.9, more preferably from 0.6 to 0.88, and from 0.63 to 0.85 is particularly preferred. If the amine-carboxylic acid base introduction ratio (S) is less than 0.55, the water solubility may be lowered. On the other hand, in order to make the amine-carboxylic acid group introduction ratio (S) over 0.9, the input energy tends to be excessive, and it cannot be said to be very realistic.

The "acyl group introduction rate (A) and amine-carboxylic acid group introduction rate (S)" as used herein refer to the number of substituents (acyl group, amine-carboxylic acid group) per mole of pyranose ring constituting chitosan. means number of moles. Each introduction rate can be calculated from, for example, the ratio of chitosan-derived nitrogen atoms by elemental analysis of the chitosan derivative. Also, each introduction rate may be calculated by analyzing the structure with NMR.

The ratio (S/A) of the introduction rate (S) of the amine-carboxylic acid group to the introduction rate (A) of the acyl group is 9 to 70, preferably 10 to 65, more preferably 11 to 60. is. The chitosan derivative of the present invention having an S/A value within the above range is useful as a polymeric surfactant (emulsifier) capable of preparing an emulsified composition (emulsion) having excellent emulsion stability.

If the S/A value is less than 9, the introduction rate (S) of the amine-carboxylic acid group is relatively too small, and the function as an emulsifier is not exhibited. On the other hand, if the S/A value exceeds 70, the introduction rate (A) of the acyl group is relatively too small, so that the function as an emulsifier for finely dispersing oil such as silicone oil is not exhibited. Sometimes.

<Method for producing chitosan derivative>
The method for producing a chitosan derivative of the present invention is a method for producing the chitosan derivative described above. with an acylating agent and a salt forming agent to introduce acyl groups and amine-carboxylic acid groups into the chitosan. The details of the method for producing the chitosan derivative of the present invention are described below.

(Reaction step)
The method for producing a chitosan derivative of the present invention has, for example, a first reaction step and a second reaction step. The first reaction step is to bring an acylating agent into contact with chitosan or chitosan into which an amine-carboxylic acid group has been introduced, and react the acylating agent with the reactive functional groups of chitosan (mainly amino groups (—NH ₂ )). This is the step of introducing an acyl group into chitosan. In the second reaction step, chitosan or acylated chitosan is brought into contact with a salt-forming agent to react with the chitosan amino group (—NH ₂ ) salt-forming agent, thereby introducing an amine-carboxylic acid group into chitosan. It is a process.

The order of the reaction steps is not particularly limited, and the desired chitosan derivative can be obtained regardless of which of the first reaction step and the second reaction step is performed first. Among them, it is preferable to first carry out the first reaction step and then carry out the second reaction step, that is, to react chitosan with the acylating agent and then with the salt-forming agent. By setting it as such an order, the yield of a chitosan derivative can be improved. After the first reaction step, the obtained intermediate material may be taken out and vacuum-dried, but the second reaction step may be carried out without taking it out.

Chitosan as a raw material is chitosan (chitosan powder) having a particle size that passes through a mesh with an opening of 1 mm (chitosan powder), preferably a chitosan that passes through a mesh with an opening of 0.5 mm, more preferably a mesh with an opening of 0.2 mm. Particle size chitosan is used. If the chitosan particle size is too large, it becomes difficult to relatively increase the acyl group introduction rate (A), and a chitosan derivative having a desired S/A value cannot be obtained.

In the first reaction step and the second reaction step, chitosan is reacted with an acylating agent or a salt-forming agent while chitosan is dispersed in a reaction solvent containing an alcoholic solvent. A chitosan derivative having an S/A value within a desired range is obtained by reacting an acylating agent or a salt-forming agent in a state in which chitosan is not dissolved in a reaction solvent but dispersed (in a heterogeneous state). be able to. In addition, when a reaction solvent containing an alcoholic solvent is used, the acylating agent and salt-forming agent to be reacted can be dissolved in the reaction solvent while the chitosan remains dispersed. As a result, the acylating agent and the salt-forming agent can be efficiently reacted with the dispersed chitosan to obtain the desired chitosan derivative.

Methanol, ethanol, isopropyl alcohol, normal propyl alcohol, isobutyl alcohol, tertiary butyl alcohol, normal butyl alcohol and the like can be used as the alcohol solvent. Among them, it is preferable to use isopropyl alcohol and ethanol, which have a boiling point of 75° C. or higher, are suitable for reaction at high temperatures, and have appropriate polarity. The content of the alcohol-based solvent in the reaction solvent is preferably 25 to 90% by mass, more preferably 30 to 80% by mass, more preferably 35 to 75% by mass, based on the total reaction solvent. is particularly preferred.

The reaction solvent preferably further contains water. Moreover, the reaction solvent can further contain a water-soluble organic solvent other than the alcoholic solvent. Examples of water-soluble organic solvents other than alcohol solvents include ketones such as dimethyl ketone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, and 1,2-dioxane; N-methylformamide, N-methyl Acetamide, N-ethylformamide, N,N-dimethylformamide, N,N-diethylformamide, N-ethylacetamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, etc. amides; sulfoxides such as dimethylsulfoxide; and the like.

The reaction temperature in the first reaction step is usually 40-100°C, preferably 55-80°C. Since reaction efficiency can be enhanced by conducting the reaction at a relatively high temperature, the reaction time of the first reaction step is usually about 0.5 to 5 hours, depending on the reaction amount. By setting the reaction temperature and reaction time as such, the acyl group can be introduced more reliably.

The reaction temperature in the second reaction step is usually 0-50°C, preferably 30-40°C. The reaction time of the second reaction step is usually 1 to 24 hours, preferably 1 to 8 hours, depending on the reaction temperature. By appropriately setting the reaction temperature and reaction time, the introduction rate of the amine-carboxylic acid group can be controlled.

After the reaction step, the desired chitosan derivative can be obtained by washing, purifying, drying, etc. as necessary.

<O/W type emulsion composition>
The O/W emulsion composition of the present invention (hereinafter also simply referred to as "emulsion composition") contains water, oil, and an emulsifier that disperses the oil in water in the form of emulsified droplets. The emulsifier is the chitosan derivative described above that functions as a polymeric surfactant. That is, since the emulsified composition of the present invention is prepared from the aforementioned chitosan derivative (emulsifier) having excellent emulsifying performance, fine emulsified droplets are formed and the emulsified composition is excellent in emulsification stability. Therefore, the emulsified composition of the present invention is extremely useful as a cosmetic or the like, taking advantage of its safety and excellent emulsification stability.

Specifically, the median diameter (d ₅₀ ) of emulsified droplets in the emulsified composition is preferably 12.0 μm or less, more preferably 10.0 μm or less, and particularly preferably 9.0 μm or less. Although the lower limit of the median diameter (d ₅₀ ) of the emulsified droplets is not particularly limited, it may be substantially 0.3 μm or more. The term "median diameter (d ₅₀ )" used herein means a volume-based cumulative 50% particle diameter measured using a measuring device such as a laser diffraction particle size distribution measuring device.

The emulsified composition can be prepared according to a conventionally known method for preparing an emulsified composition, except that the aforementioned chitosan derivative is used as an emulsifier. Examples of oils include straight silicone oils such as dimethylpolysiloxane and methylphenylpolysiloxane; various modified silicone oils such as amino-modified silicone oil and alkyl-modified silicone oil; squalane; isopropyl myristate; can be mentioned.

The chitosan derivative of the present invention can be used as, for example, a thickening agent, a dispersing agent, a surface modifier, a spreading agent, a protective colloid agent, a water retention agent, etc., in addition to the polymeric surfactant. Therefore, by containing the chitosan derivative of the present invention, in addition to the O/W emulsion composition described above, a wide range of products such as cosmetics, paints, papermaking, fibers, building materials, civil engineering materials, foods, and pharmaceuticals can be used. and materials are expected to be provided.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples. "Parts" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

<Production of chitosan derivative>
(Example 1)
[Acylation reaction]
A mushroom-derived powdery chitosan having a weight-average molecular weight (Mw) of 200,000, a deacetylation degree of 91%, and a particle size passing through a mesh with an opening of 180 μm was prepared. 15 g (dry mass) (88.8 mmol) of the prepared chitosan, 100 g of water, and 100 g of isopropyl alcohol (IPA) were placed in a beaker, and the temperature was raised to 60° C. while stirring at a rotational speed of 100 rpm using a glass feather. . 3.9 g (8.9 mmol) of myristic anhydride was added and reacted with stirring at 60° C. for 2 hours while chitosan was dispersed. After washing by repeating hot filtration and addition of IPA three times, it was dried in an oven to obtain a solid (myristoylated chitosan).

[Salt-forming reaction]
15 g of the solid obtained, 70 g of water and 130 g of IPA were placed in a beaker and kept at 30° C. with stirring at a rotation speed of 100 rpm using a glass feather. 11.4 g (88.8 mmol) of pyrrolidonecarboxylic acid (PCA) was added, and the mixture was stirred at 30° C. for 4 hours while solids were dispersed. After washing with water-containing methanol three times and IPA twice, it was dried in an oven to obtain a chitosan derivative.

(Examples 2 to 24, Comparative Examples 1 to 5)
A chitosan derivative was produced in the same manner as in Example 1 above, except that the acylation reaction and salt formation reaction were carried out under the conditions shown in Tables 1-1 and 1-2. The types (abbreviations) of "acylating agents" in Table 1-1 are shown below.
[Acylating agent]
A: myristic anhydride B: n-octanoic anhydride C: stearic anhydride D: oleic anhydride

(Comparative Example 6)
A chitosan derivative was produced in the same manner as in Example 1 above, except that chitosan was reacted with an acylating agent (myristic anhydride) at 30°C.

<Evaluation>
(Measurement and calculation of acyl group introduction rate (A) and amine-carboxylic acid base introduction rate (S))
Elemental analysis of the chitosan derivative was performed, and from the ratio of chitosan-derived nitrogen atoms, the acyl group introduction rate (A) (the number of moles of acyl groups per mole of pyranose ring constituting chitosan), and the amine-carboxylic acid group introduction rate ( S) (number of moles of amine-carboxylic acid group per mole of pyranose ring constituting chitosan) was calculated. Further, the value of S/A was calculated from the calculated acyl group introduction ratio (A) and amine-carboxylic acid base introduction ratio (S). Table 2 shows the results.

(Measurement of emulsified droplet diameter (median diameter (d ₅₀ )) and evaluation of emulsifying performance)
1 part of chitosan derivative, 49.0 parts of water, and 50 parts of dimethylsilicone oil (kinematic viscosity at 25°C: 6 mm ² /s) were mixed and stirred at 2,000 rpm for 3 minutes using a dissolver to prepare an emulsified composition. A product (emulsion) was prepared. The droplet diameter (median diameter (d ₅₀ )) of the dimethylsilicone oil in the prepared emulsion was measured using a laser diffraction particle size distribution analyzer. Table 2 shows the measurement results. Furthermore, emulsification performance of the chitosan derivative was evaluated according to the evaluation criteria shown below. Table 2 shows the evaluation results.
A: The median diameter of emulsified droplets was 6.0 µm or less.
◯: The median diameter of emulsified droplets was more than 6.0 μm and 10.0 μm or less.
Δ: The median diameter of emulsified droplets was more than 10.0 μm and 12.0 μm or less.
x: The median diameter of emulsified droplets exceeded 12.0 μm.
XX: No emulsification, and emulsified droplet size could not be measured.

(Evaluation of emulsion stability)
After storing the emulsified composition (emulsified liquid) prepared in the above "Measurement of emulsified droplet diameter (median diameter (d ₅₀ )) and evaluation of emulsifying performance" at room temperature (25 ° C.), visually observe, Emulsion stability was evaluated according to the evaluation criteria shown below. Table 2 shows the evaluation results.
A: No separation was observed even after storage for 7 days.
Good: No separation occurred after storage for 1 day, but separated after storage for 7 days.
x: Separated within 1 day.

<Preparation of emulsion>
(Example 25)
1 part of the chitosan derivative prepared in Example 3, 49.0 parts of water, and 50 parts of isopropyl myristate (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed. Using a dissolver, the mixture was stirred at 2,000 rpm for 3 minutes to prepare an emulsion, which is an O/W emulsion composition. The median diameter (d ₅₀ ) of the emulsified droplets measured using a laser diffraction particle size distribution analyzer was 6.3 μm. Also, the prepared milky lotion was stored at room temperature (25° C.) for 7 days, but no separation occurred.

The chitosan derivative of the present invention is useful as an emulsifier for preparing emulsified compositions such as cosmetics.

Claims (5)

Chitosan in which the acyl group derived from the acylating agent and the amine-carboxylic acid group derived from the salt forming agent have a weight average molecular weight of 120,000 to 3,000,000 and a degree of deacetylation of 70 to 100%. and wherein the ratio (S/A) of the introduction rate (S) of the amine-carboxylic acid group to the introduction rate (A) of the acyl group is 9 to 70. and
The chitosan having a particle size that can pass through a mesh with an opening of 1 mm is dispersed in a reaction solvent containing an alcohol solvent, and the chitosan is reacted with the acylating agent at 55 to 100° C., and then the salt-forming agent to introduce the acyl group and the amine-carboxylic acid group into the chitosan. 2. The method for producing a chitosan derivative according to claim 1 , wherein the alcohol solvent is at least one selected from the group consisting of isopropyl alcohol, normal propyl alcohol and ethanol. 3. The method for producing a chitosan derivative according to claim 1, wherein the acyl group has 7 to 20 carbon atoms. The method for producing a chitosan derivative according to any one of claims 1 to 3, wherein the salt-forming agent is at least one selected from the group consisting of pyrrolidonecarboxylic acid, ascorbic acid, glycolic acid, lactic acid, and acetic acid. The method for producing a chitosan derivative according to any one of claims 1 to 4, wherein the chitosan derivative is used as a polymeric surfactant.