JP2023035552A - Resin bead, method for manufacturing resin bead, and product using resin bead - Google Patents

Abstract

To provide resin beads which enables production of various products such as a cosmetic having excellent touch feeling and spread on skin, and is substitutable for resin particles composed of a petroleum-derived synthetic base material.SOLUTION: Particulate resin beads are formed of a resin containing at least one chitosan of chitosan and chitosan salt as a main component. An average maximum diameter is 1-20 μm, an aspect ratio defined by expression (1) is 1.5-40, a standard deviation ratio of an aspect ratio defined by expression (2) is 20% or less, and a biconcave disc degree defined by expression (3) is 0-0.3. Expression (1): A=D/h, expression (2): CV=S/D, and expression (3): B=(h-t)/D. In the expressions, A is an aspect ratio, CV is a standard deviation ratio (%) of the aspect ratio, B is a biconcave disc degree, D is an average maximum diameter (μm), h is an average maximum thickness (μm), S is a standard deviation, and t is an average minimum thickness (μm).SELECTED DRAWING: None

Description

The present invention relates to resin beads, a method for producing resin beads, and products using resin beads.

Conventionally, resin beads have been used in various fields such as matting agents, slip agents, and anti-blocking agents due to their spherical properties. Furthermore, various resin powders (resin particles) such as resin beads are used in order to improve properties such as spreadability of makeup cosmetics. However, in recent years, due to problems such as marine pollution caused by microplastics, the constituent materials of resin beads blended in cosmetics are shifting from petroleum-derived synthetic materials to natural materials.

As resin powders and resin particles made of natural materials, for example, chitosan powder in the form of amorphous flakes, which is obtained by mechanically pulverizing chitosan at low temperature and wet, and which is blended in cosmetics and the like, has been proposed (Patent Document 1). ). In addition, flat cellulose particles, which are obtained by mechanically pulverizing a cellulose-based substance to which fatty acids have been added, have been proposed to be added to cosmetics and the like (Patent Document 2).

JP-A-5-86102 Japanese Patent No. 3787598

However, the chitosan powder and cellulose particles proposed in Patent Literatures 1 and 2 do not spread very well on the skin even when blended in cosmetics, and they tend to be powdery or feel rough. Met. For this reason, it cannot be said that it is necessarily suitable as a material exhibiting a "moist feel" that is required in the market.

The present invention has been made in view of the problems of the prior art, and its object is to provide various products such as cosmetics that have excellent texture and spreadability on the skin. The object of the present invention is to provide resin beads that can be substituted for resin particles made of petroleum-derived synthetic materials, and various products such as cosmetics using the resin beads. In addition, the object of the present invention is to manufacture resin beads that can be substituted for resin particles made of petroleum-derived synthetic materials that can provide various products such as cosmetics that have excellent texture and spreadability on the skin. It is to provide a method.

That is, according to the present invention, the following resin beads are provided.
[1] Particulate resin beads made of a resin containing at least one of chitosan and chitosan salt as a main component, having an average maximum diameter of 1 to 20 μm, defined by the following formula (1): The aspect ratio is 1.5 to 40, the standard deviation rate of the aspect ratio defined by the following formula (2) is 20% or less, and the biconcave discus degree defined by the following formula (3) is 0 ~0.3 resin beads.
A=D/h (1)
A: Aspect ratio D: Average maximum diameter (μm)
h: average maximum thickness (μm)
CV=S/D (2)
CV: Standard deviation rate of aspect ratio (%)
S: standard deviation D: average maximum diameter (μm)
B=(h−t)/D (3)
B: Double concave diskity h: Average maximum thickness (μm)
t: average minimum thickness (μm)
D: average maximum diameter (μm)
[2] The resin bead according to [1], wherein the aspect ratio is 2 to 35, the standard deviation of the aspect ratio is 15% or less, and the biconcave discus degree is 0 to 0.25.
[3] The resin beads according to [1] or [2] above, wherein the chitosans have a weight average molecular weight of 15,000 to 1,500,000.
[4] The resin beads according to any one of [1] to [3], wherein the chitosan salt is chitosan sulfate.

Further, according to the present invention, there is provided a method for producing resin beads as described below.
[5] The method for producing resin beads according to any one of [1] to [4] above, wherein the temperature of the reaction solution containing chitosan, sulfuric acid, and a polar solvent is raised to 100°C or less while flowing. A method for producing resin beads, comprising the step of dissolving the chitosan and then lowering the temperature of the reaction solution while flowing it to form a precipitate.
[6] The method for producing resin beads according to [5] above, wherein the molar ratio (X/Y) of the amount (X) of sulfuric acid to the amount (Y) of chitosan is 2.0 or more.
[7] The method for producing a resin bead according to [5] or [6], further comprising a step of neutralizing the generated precipitate with an alkali.

Furthermore, according to the present invention, the following products are provided.
[8] Any product of cosmetics, dermatological agents, paints, moldings, films, coating agents, and resin compositions containing resin beads, wherein the resin beads are selected from the above [1] to [ 4].

INDUSTRIAL APPLICABILITY According to the present invention, resin beads which can be substituted for resin particles made of petroleum-derived synthetic materials, and cosmetics using the same, which can provide various products such as cosmetics having an excellent texture and spreadability on the skin. Various products such as food can be provided. In addition, according to the present invention, there is provided a method for producing resin beads that can be used as a substitute for resin particles made of petroleum-derived synthetic materials, and that can provide various products such as cosmetics that have excellent texture and spreadability on the skin. can do.

FIG. 2 is a front view schematically showing the shape of resin beads; 1 is an electron micrograph showing the microstructure of a resin bead produced in Example 1. FIG. 3 is an electron micrograph showing the microstructure of resin beads produced in Example 8. FIG.

<Resin beads>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. The resin beads of the present invention are particulate resin beads formed of a resin containing at least one of chitosan and chitosan salt as a main component. The resin beads of the present invention have an average maximum diameter of 1 to 20 μm, an aspect ratio defined by the following formula (1) of 1.5 to 40, and an aspect ratio defined by the following formula (2). is 20% or less, and the biconcave discus degree defined by the following formula (3) is 0 to 0.3. Details of the resin beads of the present invention are described below.

A=D/h (1)
A: Aspect ratio D: Average maximum diameter (μm)
h: average maximum thickness (μm)
CV=S/D (2)

CV: Standard deviation rate of aspect ratio (%)
S: standard deviation D: average maximum diameter (μm)

B=(h−t)/D (3)
B: Double concave diskity h: Average maximum thickness (μm)
t: average minimum thickness (μm)
D: average maximum diameter (μm)

(chitosans)
The resin beads are particles formed of a resin containing chitosans as a main component, preferably substantially formed of chitosans. Chitosans are at least one of chitosan and chitosan salts. 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. Chitosan salts include chitosan sulfate, chitosan salicylate, chitosan phosphate, and the like. It is preferable that the resin beads are substantially made of a chitosan salt in order to further improve the feel and spreadability on the skin.

The weight average molecular weight of chitosans is preferably 15,000 to 1,500,000, more preferably 20,000 to 1,000,000, and more preferably 25,000 to 750,000. Especially preferred. If the weight average molecular weight of the chitosan is less than 15,000, hydrolysis of the chitosan may proceed and the yield may be greatly reduced. On the other hand, if the weight average molecular weight of the chitosan exceeds 1,500,000, it may become difficult to control the shape of the precipitated resin beads.

The degree of deacetylation of chitosan is 70-100%, preferably 75-99%. If the degree of deacetylation of chitosan is less than 70%, chitin derived from the insoluble portion may remain in the product because the solubility tends to be poor during dissolution. 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.

(Shape of resin beads)
FIG. 1 is a front view schematically showing the shape of resin beads. The resin bead 10 of the embodiment shown in FIG. 1 has a biconcave disk-like structure with a gently depressed central portion, a so-called red blood cell structure. The resin beads of the present invention may include a biconcave disk-shaped resin bead 10 as shown in FIG. In FIG. 1, D is the average maximum diameter of the resin beads, h is the average maximum thickness of the resin beads, t is the average minimum thickness of the resin beads, and d is the average distance between the most projecting portions of the resin beads in the thickness direction. respectively. The "average maximum diameter D" of the resin beads means the larger one of the "average maximum width" and "average maximum length" of the resin beads.

The shape of the resin bead is measured and evaluated according to the procedure shown below. First, images of the surface and cross section of the resin bead are taken using an electron microscope. Next, the photographed images are analyzed, and the maximum diameter, maximum thickness, minimum thickness, and distance between the most projecting portions in the thickness direction of 30 or more arbitrarily selected resin beads are measured. After that, the average value of the measured maximum diameter, maximum thickness, minimum thickness, and the distance between the most protruding parts in the thickness direction is calculated, and the average maximum diameter D, average maximum thickness h, average minimum thickness t , the average distance d between the most protruding portions in the thickness direction can be obtained, respectively.

The average maximum diameter of the resin beads is 1-20 μm, preferably 2-18 μm, more preferably 2.5-15 μm. When the average maximum diameter is within the above range, excellent tactile sensation and spreadability on the skin are exhibited. Also, the difference (ht) between the average maximum thickness and the average minimum thickness of the resin beads is preferably 0 to 5 μm, more preferably 0 to 3.5 μm.

The aspect ratio of the resin beads defined by the following formula (1) is 1.5-40, preferably 2-35, more preferably 2.5-30. When the aspect ratio is within the above range, excellent tactile sensation and spreadability on the skin are exhibited. The aspect ratio of the spherical resin beads is 1.0.
A=D/h (1)
A: Aspect ratio D: Average maximum diameter (μm)
h: average maximum thickness (μm)

The standard deviation of the aspect ratio of the resin beads defined by the following formula (2) is 20% or less, preferably 15% or less, and more preferably 10% or less. That is, the aspect ratios of the resin beads of the present embodiment are relatively uniform with little variation because they are not mechanically pulverized. By making the aspect ratios relatively uniform in this way, it is easy to formulate cosmetics and the like, and it is possible to exhibit excellent tactile sensation and spreadability on the skin. The lower limit of the standard deviation of the aspect ratio is not particularly limited, and is usually 1% or more. The standard deviation of the aspect ratio of resin beads ("S" in formula (2)) can be calculated by the following formula (4).
CV=S/D (2)
CV: Standard deviation rate of aspect ratio (%)
S: standard deviation D: average maximum diameter (μm)

ｎ：サンプル数
ｘ_ｉ：サンプルの各アスペクト比

n: Number of samples x _i : Aspect ratio of each sample

The resin bead has a biconcave discoticity defined by the following formula (3) of 0 to 0.3, preferably 0 to 0.25, and more preferably 0 to 0.2. When the degree of biconcave discus is within the above range, excellent tactile sensation and spreadability on the skin can be exhibited.
B=(h−t)/D (3)
B: Double concave diskity h: Average maximum thickness (μm)
t: average minimum thickness (μm)
D: average maximum diameter (μm)

<Method for producing resin beads>
Next, a method for producing the resin beads described above will be described. The method for producing resin beads of the present invention is the above-described method for producing resin beads, wherein the reaction solution containing chitosan, sulfuric acid, and a polar solvent is heated to 100° C. or lower while flowing to dissolve chitosan. and a step (step (1)) of lowering the temperature of the reaction solution while flowing it to form a precipitate.

In step (1), first, a reaction solution containing chitosan, sulfuric acid, and a polar solvent is prepared. Sulfuric acid may be either dilute sulfuric acid or concentrated sulfuric acid. The molar ratio (X/Y) of the amount (X) of sulfuric acid to the amount (Y) of chitosan is preferably 2.0 or more, more preferably 2.5 or more, and 2.7 or more. is particularly preferred. By setting the above molar ratio to 2.0 or more, resin beads having an aspect ratio within a more preferable range can be obtained. The upper limit of the above molar ratio is not limited, and may be, for example, 8.0 or less.

Chitosan used as a raw material tends to become low-molecular-weight during the manufacturing process. For this reason, it is preferable that the chitosan used as a raw material has a somewhat larger molecular weight than the chitosans constituting the resin beads to be produced. Specifically, the weight average molecular weight of chitosan used as a raw material is preferably 50,000 to 3,000,000, more preferably 70,000 to 2,500,000, and more preferably 80,000 to 3,000,000. 2,200,000 is particularly preferred. By using chitosan having a weight-average molecular weight within the above range as a raw material, it is possible to obtain resin beads formed of a resin containing chitosans as a main component with a desired weight-average molecular weight.

Water is usually used as the polar solvent. Examples of polar solvents other than water include N-methylpyrrolidone, N-ethylpyrrolidone, dimethylsulfoxide and the like.

In step (1), the temperature of the prepared reaction solution is raised while flowing to dissolve chitosan. A stirring blade or the like may be used to flow the reaction solution. The temperature of the reaction solution is raised to 100° C. or lower, preferably 95° C. or lower, more preferably 90° C. or lower. If the temperature of the reaction solution is raised to over 100° C., the biconcave discoticity of the obtained resin beads becomes too large. The lower limit of the heating temperature of the reaction solution is not limited, and may be, for example, 55° C. or higher.

It is preferable to keep the reaction solution heated to dissolve the chitosan for a certain period of time while the temperature is raised. The retention time is preferably 0.5 hours or longer, more preferably 2 hours or longer, and particularly preferably 3 hours or longer. By maintaining the temperature of the reaction solution in which chitosan is dissolved for a certain period of time, it is possible to obtain resin beads exhibiting superior tactile sensation and spreadability on the skin.

A precipitate can be formed by holding the reaction solution in which chitosan is dissolved for a certain period of time as necessary, and then lowering the temperature while fluidizing the solution. It is necessary to lower the temperature while fluidizing the reaction solution, and if the temperature is lowered while the reaction solution is left standing without fluidizing, resin beads having a desired shape cannot be obtained. For the flow of the reaction solution, for example, a stirring blade or the like may be used to stir at a speed of preferably 50 rpm or higher, more preferably 100 rpm or higher, and particularly preferably 150 rpm or higher. A precipitate can be formed by lowering the temperature of the reaction solution while stirring, preferably to 50° C. or lower, more preferably to room temperature (25° C.) or lower. By washing and drying the resulting precipitate, resin beads substantially formed of chitosan sulfate can be obtained.

It is preferable that the method for producing resin beads further includes a step of neutralizing the precipitate produced in the above step (1) with an alkali. By neutralizing the precipitate with an alkali, resin beads substantially formed of chitosan can be obtained. The type of alkali that neutralizes the precipitate is not particularly limited, and alkali metal hydroxides, alkaline earth metal hydroxides, and the like can be used.

<Various products>
The product of the present invention is any one of cosmetics, dermatological agents, paints, moldings, films, coating agents, and resin compositions containing the resin beads described above. Since the resin beads described above have a specific shape, they have excellent tactile sensation and spread well on the skin. Therefore, by containing these resin beads, cosmetics, dermatological agents, paints, and moldings that are imparted with excellent tactile sensation and spreadability on the skin without using resin particles made of petroleum-derived synthetic materials. Various products such as bodies, films, coatings, and resin compositions can 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 resin beads>
(Example 1)
A mushroom-derived powdery chitosan having a weight average molecular weight (Mw) of 200,000 and a degree of deacetylation of 98% was prepared. 2.5 g (dry mass) (14.8 mmol) of prepared chitosan and 83.5 g of water were placed in a flask. Using a glass blade, 5.9 g (59.2 mmol) of 98% sulfuric acid was added dropwise over 5 minutes while stirring at a rotational speed of 100 rpm and mixed. Using a mantle heater, the temperature of the reaction solution was raised to 80° C. to dissolve the contents. After the liquid temperature of the reaction liquid reached 80° C., the same temperature was maintained for 5 hours. The reaction solution was filtered through a glass filter paper, and the obtained filtrate was gradually cooled while being stirred at a rotational speed of 200 rpm to flow. When the liquid temperature of the reaction solution reached around 50°C, it was confirmed that a precipitate was formed. The reaction liquid was further slowly cooled while being stirred and fluidized, and when the liquid temperature reached room temperature (25° C.), the liquid was decanted and the supernatant liquid was removed to obtain a precipitate. The obtained precipitate was washed with water, and after repeating the washing until the pH of the washing solution reached 7, the washing was freeze-dried to obtain resin beads composed of chitosan sulfate. The resulting resin beads had an average width of 2.8 μm and an average length of 2.8 μm. That is, the average maximum diameter D of the resin beads was 2.8 μm. The resin beads had an aspect ratio A of 5.5, a biconcave discus degree B of 0.01, and a standard deviation rate CV of the aspect ratio of 7.1%.

(Examples 2 to 16)
Resin beads were obtained in the same manner as in Example 1, except that the conditions shown in Table 1 were used. Table 2 shows the properties of the obtained resin beads. Electron micrographs showing the microstructures of the resin beads produced in Examples 1 and 8 are shown in FIGS. 2 and 3, respectively.

(Comparative example 1)
A mushroom-derived powdery chitosan having a weight average molecular weight (Mw) of 200,000 and a degree of deacetylation of 98% was prepared. 2.5 g (dry mass) (14.8 mmol) of prepared chitosan and 83.5 g of water were placed in a flask. Using a glass blade, 5.9 g (59.2 mmol) of 98% sulfuric acid was added dropwise over 5 minutes while stirring at a rotational speed of 100 rpm and mixed. Using a mantle heater, the temperature of the reaction solution was raised to 80° C. to dissolve the contents. After the liquid temperature of the reaction liquid reached 80° C., the same temperature was maintained for 5 hours. The reaction solution was filtered through a glass filter paper, and the obtained filtrate was allowed to stand without stirring and gradually cooled. When the liquid temperature of the reaction solution reached around 50°C, it was confirmed that a precipitate was formed. The reaction solution was allowed to stand still and further cooled. When the solution temperature reached room temperature (25° C.), the solution was decanted and the supernatant was removed to obtain a precipitate. The obtained precipitate was washed with water, and after repeating the washing until the pH of the washing solution reached 7, the washing was freeze-dried to obtain resin beads composed of chitosan sulfate. The resulting resin beads had an average width of 4.9 μm and an average length of 4.9 μm. That is, the average maximum diameter D of the resin beads was 4.9 μm. The resin beads had an aspect ratio A of 1.2 (almost spherical), a biconcave discus degree B of 0.02, and a standard deviation rate CV of the aspect ratio of 1.2%.

(Comparative example 2)
A mushroom-derived powdery chitosan having a weight average molecular weight (Mw) of 200,000 and a degree of deacetylation of 98% was prepared. 2.5 g (dry mass) (14.8 mmol) of the prepared chitosan and 83.5 g of water were placed in a sealable container. While stirring using a spatula, 5.9 g (59.2 mmol) of 98% sulfuric acid was added dropwise over 5 minutes and mixed. The container was sealed and heat-pressure treated at 121° C. for 20 minutes using an autoclave. The reaction solution was filtered through a glass filter paper, and the obtained filtrate was allowed to stand without stirring and gradually cooled. When the liquid temperature of the reaction solution reached around 50°C, it was confirmed that a precipitate was formed. The reaction solution was allowed to stand still and further cooled. When the solution temperature reached room temperature (25° C.), the solution was decanted and the supernatant was removed to obtain a precipitate. The obtained precipitate was washed with water, and after repeating the washing until the pH of the washing solution reached 7, the washing was freeze-dried to obtain resin beads composed of chitosan sulfate. The resulting resin beads had an average width of 16.9 μm and an average length of 16.9 μm. That is, the average maximum diameter D of the resin beads was 16.9 μm. The resin beads had an aspect ratio A of 1.6, a biconcave discus degree B of 0.31, and a standard deviation rate CV of the aspect ratio of 2.5%.

(Comparative Example 3)
A mushroom-derived powdery chitosan having a weight average molecular weight (Mw) of 200,000 and a degree of deacetylation of 98% was prepared. The prepared chitosan was treated according to the method described in "Example 7" of Patent Document 2 (Japanese Patent No. 3787598) to obtain chitosan particles. The resulting chitosan particles had an average width of 10.5 μm and an average length of 10.4 μm. That is, the chitosan particles had an average maximum diameter D of 10.5 μm. The chitosan particles had an aspect ratio A of 42.0, a biconcave discus degree B of 0.00, and a standard deviation rate CV of the aspect ratio of 45.1%.

(Example 17)
The resin beads produced in Example 1 were neutralized in hydrous alcohol to obtain resin beads formed of chitosan. The resulting resin beads had an average width of 2.8 μm and an average length of 2.8 μm. That is, the average maximum diameter D of the resin beads was 2.8 μm. The resin beads had an aspect ratio A of 5.3, a biconcave discus degree B of 0.01, and a standard deviation rate CV of the aspect ratio of 5.3%.

<Evaluation of resin beads>
(tactile sensation)
The tactile sensation of the resin beads was sensory evaluated by a panel test of 10 people. Touch the resin beads, comprehensively judge "smoothness", "good spreadability on the skin", and "moist feeling", and score on a scale of 5 according to the evaluation criteria shown below, and the average score of 10 people. was calculated. Table 2 shows the results.
5: Good 4: Somewhat good 3: Average 2: Somewhat bad 1: Bad

<Production of Cosmetics>
(Examples 1C to 17C, Comparative Examples 1C to 3C)
Various ingredients conventionally used as raw materials for cosmetics were mixed to produce cosmetics. Specifically, first, component (A) (hydrophobic component) shown in Table 3 was mixed and heated to dissolve. On the other hand, component (B) (hydrophilic component) shown in Table 3 was mixed and heated to dissolve. In addition, component (C) (powder component and resin beads) shown in Table 3 was blended and mixed until uniform to obtain a powder mixture. While stirring the mixture of component (A), the powder mixture of component (C) was added, and then the mixture of component (B) was added and mixed until uniform to obtain a cosmetic.

<Evaluation of cosmetics>
A sensory evaluation was conducted by a panel test of 10 people regarding the feel of the cosmetics and spreadability on the skin. "Good touch feeling" and "spreadability on the skin" were judged, each was scored on a scale of 5 out of 5 according to the evaluation criteria shown below, and the average score of 10 people was calculated. Table 4 shows the results.
5: Good 4: Somewhat good 3: Average 2: Somewhat bad 1: Bad

As shown in Table 4, it can be seen that the use of the resin beads of Examples produced cosmetics with excellent tactile feel and spreadability on the skin. In addition, by using the resin beads of Examples, not only cosmetics, but also various products such as dermatological agents, paints, moldings, films, coating agents, and resin compositions have excellent tactile sensation and spreadability. It was confirmed that such characteristics can be given.

By using the resin beads of the present invention, it is possible to provide a cosmetic that has a good feel, spreads well on the skin, and is less prone to dusting. Therefore, the resin beads of the present invention are useful as constituent materials for various products such as cosmetics, dermatological agents, paints, moldings, films, coating agents, and resin compositions.

10: resin beads D: average maximum diameter h: average maximum thickness t: average minimum thickness d: average distance between the most protruding parts in the thickness direction

Claims (8)

Particulate resin beads formed of a resin containing at least one of chitosan and chitosan salt as a main component,
The average maximum diameter is 1 to 20 μm,
The aspect ratio defined by the following formula (1) is 1.5 to 40,
The standard deviation rate of the aspect ratio defined by the following formula (2) is 20% or less,
A resin bead having a biconcave discus degree defined by the following formula (3) of 0 to 0.3.
A=D/h (1)
A: Aspect ratio D: Average maximum diameter (μm)
h: average maximum thickness (μm)
CV=S/D (2)
CV: Standard deviation rate of aspect ratio (%)
S: standard deviation D: average maximum diameter (μm)
B=(h−t)/D (3)
B: Double concave diskity h: Average maximum thickness (μm)
t: average minimum thickness (μm)
D: average maximum diameter (μm) The aspect ratio is 2 to 35,
The standard deviation rate of the aspect ratio is 15% or less,
2. The resin bead according to claim 1, wherein the biconcave discus degree is 0 to 0.25. 3. The resin beads according to claim 1, wherein the chitosans have a weight average molecular weight of 15,000 to 1,500,000. The resin beads according to any one of claims 1 to 3, wherein the chitosan salt is chitosan sulfate. A method for producing a resin bead according to any one of claims 1 to 4,
a step of heating a reaction solution containing chitosan, sulfuric acid, and a polar solvent to 100° C. or less while flowing to dissolve the chitosan, and then lowering the temperature of the reaction solution while flowing to form a precipitate. A method for producing resin beads. 6. The method for producing resin beads according to claim 5, wherein the molar ratio (X/Y) of the amount (X) of sulfuric acid to the amount (Y) of chitosan is 2.0 or more. 7. The method for producing resin beads according to claim 5, further comprising the step of neutralizing the generated precipitate with an alkali. Any product of cosmetics, dermatological agents, paints, moldings, films, coating agents, and resin compositions containing resin beads,
A product, wherein the resin beads are the resin beads according to any one of claims 1 to 4.

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