WO2024106407A1

WO2024106407A1 - Composition containing polymer particles and production method for composition containing polymer particles

Info

Publication number: WO2024106407A1
Application number: PCT/JP2023/040850
Authority: WO
Inventors: 貴史山崎; 俊一辻; 小百合山田
Original assignee: キリンホールディングス株式会社
Priority date: 2022-11-15
Filing date: 2023-11-14
Publication date: 2024-05-23

Abstract

Provided is a composition containing water and polymer particles that contain 2-[4-(diethylamino)-2-hydroxybenzoyl] hexyl benzoate (DHHB), a polymer containing a repeating unit derived from a monomer able to form a homopolymer having a glass transition temperature of at least 80°C, and a polyvinyl alcohol, wherein the average particle size of the polymer particles is at most 350 nm, the PdI is at most 0.2, and the DHHB content is at least 5.5 mass%. This composition has excellent long-term stability while having a high DHHB content. This composition can be produced using a production method that comprises agitating and emulsifying a reaction solution containing DHHB, the abovementioned monomer, a polyvinyl alcohol, and water, and subjecting the monomer to a polymerization reaction at the same time as the emulsification or after the emulsification.

Description

Compositions containing polymer particles and methods for making compositions containing polymer particles

The present invention relates to a composition comprising polymer particles and a method for producing a composition comprising polymer particles. In particular, the present invention relates to a composition comprising polymer particles containing 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate (DHHB) and a method for producing the composition.

2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate (hereinafter referred to as "DHHB") is known as a UVA ultraviolet absorbing agent used mainly in sunscreen cosmetics and the like (Patent Document 1, Non-Patent Document 1). In using ultraviolet absorbing agents such as DHHB, in order to reduce irritation to the skin when directly applied to the skin and to improve the adsorption to the skin, a technique for encapsulating the ultraviolet absorbing agent in polymer particles has been developed.
For example, Patent Document 2 reports cationic polymer particles encapsulating DHHB, which are polymers comprising structural units derived from a cationic polymerization initiator and structural units derived from a monomer containing a carbon-carbon double bond.
Furthermore, for example, Patent Document 3 reports a cosmetic preparation containing microcapsules encapsulating an ultraviolet absorbent, characterized in that the ultraviolet absorbent is at least in a liquid or amorphous state, the microcapsules are made of a polyurethane/polyurethane resin wall film, the average particle size is 0.1 to 10 μm, and the wall film material accounts for 20 to 95% by weight of the microcapsules.

JP 2012-193138 A JP 2021-088555 A Japanese Patent Application Laid-Open No. 07-267841

When the present inventors were attempting to manufacture a polymer particle-containing composition with a higher DHHB content using the manufacturing method described in Patent Document 2, they discovered for the first time that there was a problem with the formation of aggregates over time. A polymer particle-containing composition in which aggregates had formed would not return to the state it was in immediately after manufacture even when shaken, making it unsuitable for use, for example, as a cosmetic. The present invention has been made to solve this problem. That is, an object of the present invention is to provide a polymer particle-containing composition that contains DHHB, has a high DHHB content, and has excellent stability over time. Another object of the present invention is to provide a method for manufacturing the above composition.

The inventors further conducted intensive research into the manufacturing method of polymer particle-containing compositions and discovered that polymer particle-containing compositions manufactured by a method different from conventional methods have a high DHHB content and excellent stability over time. Based on this knowledge, the inventors conducted further research and have completed the present invention.

Specifically, the present invention is as follows.
<1> Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A composition comprising: component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher; and component C: polymer particles containing polyvinyl alcohol; and water,
The average particle size of the polymer particles is 350 nm or less,
The polymer particles have a polydispersity index PdI of 0.2 or less as measured by a dynamic light scattering method;
The composition, wherein the content of component A in the composition is 5.5 mass% or more.
<2> The composition according to <1>, wherein the content of component A is 26 to 67 mass% relative to the content of component B.
<3> The composition according to <1> or <2>, wherein the monomer is styrene or methyl methacrylate.
<4> The composition according to any one of <1> to <3>, wherein component B is a polymer having a cationic functional group.
<5> The composition according to any one of <1> to <4>, wherein the content of component A in the polymer particles is 20 mass% or more.
<6> The composition according to any one of <1> to <5>, which is substantially free of a surfactant.

<7> Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A composition comprising: component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher; and component C: polymer particles containing polyvinyl alcohol, wherein the polymer particles have an average particle size of 350 nm or less;
The content of component A is 26 to 67% by mass relative to the content of component B,
The composition, wherein the polymer particles have a polydispersity index PdI of 0.2 or less as measured by a dynamic light scattering method.
<8> The composition according to <7>, wherein the monomer is styrene or methyl methacrylate.
<9> The composition according to <7> or <8>, wherein component B is a polymer having a cationic functional group.

<10> Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A method for producing a composition comprising component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher, and component C: polymer particles containing polyvinyl alcohol, the method comprising the steps of:
The production method includes a step of emulsifying a reaction liquid containing at least component A, the monomer, component C, and water, and a step of carrying out a polymerization reaction of the monomer simultaneously with or after the emulsification.
<11> The method according to <10>, wherein the total mass of the monomers contained in the reaction solution before the start of the polymerization reaction is 1.5 to 3.9 times the total mass of component A, and the total mass of the water is 10 to 15 times the total mass of component A.
<12> The method according to <10> or <11>, wherein the reaction solution is not diluted during the course of the polymerization reaction.
<13> The method according to any one of <10> to <12>, wherein the emulsification is carried out for 10 minutes or more and at a stirring speed of 6,000 rpm or more.
<14> The method according to any one of <10> to <13>, wherein the polymerization reaction is carried out in the presence of a polymerization initiator.
<15> The method according to any one of <10> to <14>, wherein the reaction liquid before the emulsification does not contain a polymerization initiator, and further comprises a step of adding a polymerization initiator to the reaction liquid after the emulsification.
<16> The method according to <14> or <15>, wherein the polymer particles contain a polymer having the repeating unit and a residue of the polymerization initiator.
<17> The method according to <16>, wherein the residue is a residue having a cationic functional group.

<18> The method according to any one of <10> to <17>, wherein the reaction liquid before emulsification contains component B.
<19> The method according to <18>, wherein the monomer is styrene and component B is polystyrene.
<20> The method according to any one of <10> to <19>, wherein the composition is the composition according to any one of <1> to <9>.
<21> The method according to any one of <10> to <20>, wherein the content of component A in the composition relative to the content of component A in the reaction liquid is 70 mass% or more.

The present invention provides a polymer particle-containing composition that has a high DHHB content and excellent stability over time, and a method for producing the same.

FIG. 1 shows the relative amounts of DHHB in aqueous alcohol containing example compositions: 10% by weight ethanol (E_10), 20% by weight 1,3-butanediol (B_20), 10% by weight 1,2-pentanediol (P_10), 2.5% by weight 1,2-hexanediol (H_2.5). 1 shows SEM images of hair fibers treated with water or polymer particle compositions: (A) water (control), (B) polymer particle composition of Reference Example S1, (C) polymer particle composition of Reference Example S2, (D) magnified image of the boxed area in (B). Scale bar (white) for (A)-(C) is 10 μm, scale bar (black) for (D) is 3 μm.

The present invention will be described in detail below.
In the following description, the amount of a substance, such as the content, is expressed by mass unless otherwise specified. Furthermore, a numerical range expressed using "to" means a range including the numerical values before and after "to" as the lower and upper limits.

<Polymer particle-containing composition>
One aspect of the present invention relates to a composition containing polymer particles.
The composition of this embodiment contains DHHB (2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate; sometimes referred to as "Component A" in this specification).

DHHB dissolves in oils but precipitates at low temperatures and has low solubility in water. Therefore, the DHHB present in the composition of this embodiment is present encapsulated in polymer particles. The composition of this embodiment is preferably an oil-in-water emulsion in which polymer particles containing DHHB are dispersed in an aqueous medium.

In the composition of this embodiment, the average particle size of the polymer particles is 350 nm or less. By having the average particle size in this range, the polymer particles are less likely to aggregate over time, making it possible to provide a stable composition.
In this embodiment, the average particle size is represented by the hydrodynamic average particle size (Z-Ave) measured by a known dynamic light scattering method. The hydrodynamic average particle size measured by the dynamic light scattering method is calculated from the temporal variation of the scattered light intensity measured from particles undergoing Brownian motion in a dispersion medium. The scattered light intensity can be measured, for example, using a Zetasizer Nano ZSP (Malvern Instruments Limited, UK). The Zetasizer Nano ZSP is equipped with a 10 mW He-Ne laser with a wavelength of 633 nm.
The average particle size of the polymer particles in the composition of this embodiment is not particularly limited as long as it is 350 nm or less, but is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more. Within this range, the necessary amount of DHHB can be encapsulated.

In addition, in the composition of this embodiment, the polydispersity index (PdI) of the polymer particles measured by dynamic light scattering is 0.2 or less, and preferably 0.1 or less. PdI can be measured, for example, using a Zetasizer Nano ZSP (Malvern Instruments). PdI is used as an index for evaluating the width of the particle size distribution of the polymer particles in the composition together with the average particle size. In a composition (emulsion) containing polymer particles with a large width of the particle size distribution, a phenomenon of emulsion collapse called Ostwald ripening is likely to occur. Ostwald ripening is a phenomenon in which a solubility difference occurs between particles with different particle sizes due to the difference in curvature of the oil-water interface, as shown by Kelvin's law, and molecular diffusion of oil occurs from small oil droplets to large oil droplets, causing the large oil droplets to become even larger. The composition of this embodiment has a PdI of 0.2 or less. By keeping the content within this range, the polymer particles are less likely to aggregate over time, making the composition stable.

In addition, the average zeta potential of the polymer particles in the composition of this embodiment is not particularly limited, but in order to further suppress the occurrence of aggregation in the composition, it is preferably +10 mV to +70 mV, and more preferably +30 mV to +70 mV.
In this embodiment, the average zeta potential is calculated from the electrophoretic migration velocity of the polymer particles. The average zeta potential can be measured, for example, using a Zetasizer Nano ZSP (Malvern Instruments).

The polymer particles in the composition of this embodiment contain at least DHHB (component A), a polymer containing repeating units derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80°C or higher (sometimes referred to herein as "polymer X" or "component B"), and polyvinyl alcohol (sometimes referred to herein as "component C").

The polymer particles may contain other components in addition to components A to C. Examples of other components include a polymerization initiator added during the formation of the polymer particles, an oil-soluble UV absorber other than DHHB, or a polymer other than polymer X. The purpose of adding a polymer other than polymer X may be, for example, to promote particle formation. Examples of polymers other than polymer X include polystyrene, and the polymer other than polymer X can be dissolved in the monomer solution at the beginning of the reaction to promote the formation of polymer particles.
The content of components other than components A to C in the polymer particles is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the content of all components in the polymer particles.

The content of the polymer particles in the composition of this embodiment is preferably 20% by mass or more, more preferably 22% by mass or more, based on the total mass of the composition. The content of the polymer particles in the composition of this embodiment is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on the total mass of the composition.
The content (mass) of polymer particles in the polymer particle-containing composition corresponds to the solid content mass (dry mass) of the composition when the composition contains only the components that can be removed by drying process (water or solvent such as unreacted monomer) as the components other than polymer particles.In addition, when the components other than polymer particles are dissolved in the composition, the components can be removed by centrifugation, so the dry mass of the precipitate after centrifugation corresponds to the content (mass) of polymer particles.

The content of DHHB (component A) in the polymer particles (the ratio of the content of DHHB to the content of all components of the polymer particles in the composition) is preferably 20% by mass or more, more preferably 22% by mass or more, and preferably 33% by mass or less, more preferably 31% by mass or less. Within this range, a composition can be preferably obtained that has a high DHHB content and is stable with the polymer particles less likely to aggregate over time.

The content of DHHB in the composition of this embodiment is preferably 5.5% by mass or more. In other words, the content of DHHB is preferably 5.5% by mass or more relative to the total mass of the composition of this embodiment. The composition of this embodiment contains such a high content of DHHB that it is useful, for example, as a cosmetic ingredient that has a high UV protection effect even in small amounts. The content of DHHB in the composition is also preferably, for example, 5.7% by mass or more, 5.8% by mass or more, 6.0% by mass or more, or 6.2% by mass or more. There is no particular upper limit, but it is usually sufficient if it is 10% by mass or less. The composition of this embodiment can have a DHHB content of 5.5% by mass or more by increasing the polymer particle concentration as well as the content of DHHB in the polymer particles.

The DHHB content in the composition can be measured using known methods such as those described in "Hygienic Testing Methods - Commentary 2015" (edited by the Pharmaceutical Society of Japan, Kanehara Publishing (2015)). For example, DHHB can be extracted from the composition with tetrahydrofuran and chloroform, and then measured using high performance liquid chromatography (using absorbance at 350 nm as an index).

A polymer (polymer X) containing repeating units derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80°C or higher is a polymer produced by a polymerization reaction of a monomer capable of forming a homopolymer having a glass transition temperature of 80°C or higher (sometimes referred to as "monomer X" in this specification). As described below, in the polymerization reaction of monomer X to obtain polymer X, other monomers besides monomer X may also react with monomer X and become constituent units of polymer X.

Monomer X is a monomer that, when homopolymerized at a sufficient degree of polymerization such that the glass transition temperature does not fluctuate, results in a homopolymer with a glass transition temperature of 80°C or higher. Preferably, the monomer is one that results in a homopolymer with a glass transition temperature of 80 to 200°C, more preferably, one that results in a homopolymer with a glass transition temperature of 80 to 180°C, and even more preferably, one that results in a homopolymer with a glass transition temperature of 80°C to 150°C.

The glass transition temperature of the resulting homopolymer can be measured using differential scanning calorimetry (DSC). The specific method for measuring DSC is in accordance with the method described in JIS K 7121 (1987).

As monomer X, a monomer containing a carbon-carbon double bond is preferable. Examples of monomers containing a carbon-carbon double bond include vinyl compound monomers, such as acrylamides, methacrylamides, acrylic acids, esters of acrylic acids, methacrylic acids, esters of methacrylic acids, and styrenes.

Specific examples of monomer X include styrene, methyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, acrylic acid, N,N-dimethylacrylamide, dimethyl itaconate, and dimethyl fumarate. Among these, styrene or methyl methacrylate is preferred, and styrene is more preferred. Since DHHB has high solubility in styrene, the content of DHHB in the polymer particles can be increased when styrene is used as monomer X.
The glass transition temperatures of homopolymers with a sufficient degree of polymerization are as follows: styrene: 100°C, methyl methacrylate: 105°C, isopropyl methacrylate: 83°C, cyclohexyl methacrylate: 107°C, phenyl methacrylate: 110°C, acrylic acid: 101°C, N,N-dimethylacrylamide: 121°C, dimethyl itaconate: 100°C, and dimethyl fumarate: 100°C.

In polymer X, the repeating units derived from monomer X may be one type or two or more types. For example, polymer X may contain only repeating units derived from styrene, only repeating units derived from methyl methacrylate, only repeating units derived from acrylic acid, repeating units derived from styrene and repeating units derived from methyl methacrylate, repeating units derived from styrene and repeating units derived from acrylic acid, or repeating units derived from styrene, repeating units derived from methyl methacrylate, and repeating units derived from acrylic acid. Polymer X preferably contains only repeating units derived from styrene or only repeating units derived from methyl methacrylate, and more preferably contains only repeating units derived from styrene, as repeating units derived from monomer X.

There are no particular limitations on polymer X as long as it contains a repeating unit derived from monomer X in part or in whole. For example, polymer X may further contain structural units derived from other monomers other than the repeating units derived from monomer X. Examples of other monomers include vinyl acetate. The ratio of repeating units derived from monomer X to the total mass of polymer X may be 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more. It is particularly preferable that polymer X does not contain structural units derived from other monomers other than the repeating units derived from monomer X.

Furthermore, the polymer X may contain a structural unit derived from a bifunctional crosslinking monomer as a structural unit derived from another monomer other than the repeating unit derived from monomer X. Examples of the bifunctional crosslinking monomer include monomers containing two or more vinyl groups in the molecule. Specific examples include N,N'-methylenebisacrylamide, N,N'-ethylenebisacrylamide, N,N'-methylenebismethacrylamide, N,N'-ethylenebismethacrylamide, ethylene glycol diacrylate, and ethylene glycol dimethacrylate. By including a structural unit derived from a bifunctional crosslinking monomer as a structural unit derived from another monomer, polymer X can be a branched polymer.

Polymer X may be either a linear polymer or a branched polymer without any particular limitation, but from the viewpoint of forming polymer particles with excellent stability over time, it is preferable that the polymer X is a linear polymer.

Furthermore, the polymer X may have a substituent at the polymer end or at the side chain. The substituent may be derived from the monomer X or another monomer, may be introduced during the polymerization reaction, or may be introduced in a reaction after the polymerization reaction. The substituent may be, for example, a residue of a polymerization initiator during the polymerization reaction, as described later.
The substituent is preferably an aryl group or a polar group. The polar group is preferably a cationic functional group. The cationic functional group is preferably present at one or both of the polymer terminals.

In order to form polymer particles whose surfaces are covered with positive charges, it is particularly preferable that polymer X is a linear polymer having cationic functional groups at the ends. Polymer particles whose surfaces are covered with positive charges have high adsorption to skin and hair, and are suitable for use in cosmetics, etc.

The weight average molecular weight Mw of polymer X in the composition of this embodiment is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, and even more preferably 10,000 to 400,000. The number average molecular weight Mn of polymer X is preferably 1,000 to 500,000, more preferably 3,000 to 400,000, and even more preferably 5,000 to 300,000. By setting the Mw and Mn of polymer X within these ranges, it is possible to easily adjust the particle size of the polymer particles made of polymer X.

In this embodiment, the weight average molecular weight Mw and the average molecular weight Mn can be measured by gel permeation chromatography (GPC) and obtained as polystyrene equivalent values. Specifically, the polymer particles dissolved in an organic solvent or the like in advance are measured using a JASCO GPC system (JASCO PU-2080 pump, JASCO RI-2031 differential refractometer, JASCO CO-2060 column oven, Shodex GPC KD-806M column), and the weight average molecular weight Mw and the average molecular weight Mn can be calculated using a calibration curve obtained using a polystyrene standard sample.

In the composition of this embodiment, the content of polymer X (component B) may be about 1.5 to 3.9 times the content (mass) of DHHB (component A), and preferably 2 to 3.5 times. In other words, the content of DHHB (component A) may be about 26 to 67% by mass, and preferably 30 to 50% by mass, of the content of polymer X (component B). Within this range, the required content of DHHB in the polymer particles is ensured, leakage of DHHB from the polymer particles can be prevented, and aggregation of the polymer particles accompanied by crystallization of the leaked DHHB can be further prevented.

The polymer particles in the composition of this embodiment contain polyvinyl alcohol (component C). Polyvinyl alcohol has traditionally been used as a dispersant to impart mechanical or freezing stability to compositions (emulsions) containing polymer particles. The polymer particles formed of polymer X (component B) encapsulating DHHB (component A) are further modified with polyvinyl alcohol (component C) to improve salt tolerance.

The average degree of polymerization of polyvinyl alcohol may be about 100 to 1000, more preferably 100 to 500, and even more preferably 100 to 300. When polyvinyl alcohol with an average degree of polymerization of about 100 to 300 is used, the size of the droplets in the emulsion reaction liquid during production can be made about 1000 nm or less, making it easy to adjust the average particle size of the polymer particles to 350 nm or less. In this case, the droplets are stable, for example, even when an inert gas is blown in before or at the start of the polymerization reaction.

The polyvinyl alcohol may have some or all of the hydroxyl groups in its structure acetylated. For example, the polyvinyl alcohol may be one produced by saponifying polyvinyl acetate. The degree of saponification may be 70 mol% or more, and preferably 75 mol% or more.
In the composition of this embodiment, the content of polyvinyl alcohol is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, based on the content of polymer X. Within this range, a composition having a high DHHB content and being stable with polymer particles that are unlikely to aggregate over time can be preferably obtained.

In the composition of this embodiment, the content of polymer X (component B) and/or polyvinyl alcohol (component C) can be calculated using infrared absorption spectrum (IR) and/or nuclear magnetic resonance spectrum (NMR), etc. Specifically, first, the polymer particles separated by centrifugation or filter filtration are dissolved in an organic solvent, etc., and the constituent molecules after dissolution are purified by appropriate column chromatography, etc., and each constituent molecule is measured by IR and/or NMR, etc. to identify polymer X (component B) or polyvinyl alcohol (component C). Then, a calibration curve is created using a standard sample of polymer X (component B) or polyvinyl alcohol (component C) to show the relationship between the content and the spectral peak intensity in IR and/or NMR, etc. Next, the content of polymer X (component B) or polyvinyl alcohol (component C) can be calculated from the value of the spectral peak intensity obtained by measuring polymer X (component B) or polyvinyl alcohol (component C) in the polymer particles by IR and/or NMR, etc. using the obtained calibration curve.

The composition of this embodiment contains water. The water is contained to make the composition an oil-in-water emulsion composition, and is not particularly limited as long as it is normally used in cosmetics and the like. Examples of water include purified water, pure water, Elix (registered trademark) water (water treated by reverse osmosis membrane and continuous ion exchange), hot spring water, deep sea water, and steam distilled water from plants, and one or more types can be appropriately selected and used as necessary. The content is not particularly limited, and can be appropriately contained in an amount corresponding to the content of other components, or in an amount that will result in a composition having the desired characteristics in the manufacturing method of the composition described below. For example, the content of water in the composition of this embodiment may be in the range of 10 to 40 masses relative to the total mass of the composition. In addition, the total mass of water in the composition is preferably in the range of 10 to 15 times the total mass of component A, and more preferably in the range of 12 to 15 times.

In addition, the composition of this embodiment may contain, for example, a polar solvent other than water. Examples of polar solvents include alcohols such as ethanol. The amount of polar solvent can be appropriately selected, but as described below, in the production of the composition of this embodiment, from the viewpoint of improving the conversion rate from monomer (styrene monomer, etc.) to polymer, it is preferable that the composition of this embodiment does not substantially contain ethanol.
In addition, the composition of this embodiment may contain a surfactant (emulsifier), but it is preferable that it does not substantially contain a surfactant. This is because a polymer particle-containing composition that does not contain a surfactant is preferable for cosmetic applications. Here, when "substantially does not contain a surfactant", for example, the surfactant content in the composition of this embodiment is 1.5 mM or less, preferably 1.0 mM or less, more preferably 0.5 mM or less, or 0.05% by mass or less, preferably 0.01% by mass or less, based on the total mass of the composition of this embodiment.

The composition of this embodiment may contain a monomer (a raw material constituting polymer X that has not reacted). The monomer may be present dissolved or dispersed in water as a component other than the polymer particles. The content of the monomer relative to the total mass of the composition of this embodiment is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

In one embodiment, the composition of this aspect comprises:
comprising polymer particles comprising component A, component B, and component C, and water;
The average particle size of the polymer particles is 350 nm or less,
The polymer particles have a polydispersity index PdI of 0.2 or less as measured by a dynamic light scattering method;
The content of component A in the composition is 5.5% by mass or more.

In another embodiment, the composition of this aspect comprises:
A composition comprising polymer particles comprising component A, component B, and component C,
The average particle size of the polymer particles is 350 nm or less,
The content of component A is 26 to 67% by mass relative to the content of component B,
The polymer particles have a polydispersity index PdI of 0.2 or less as measured by a dynamic light scattering method.

<Method of producing polymer particle-containing composition>
Another aspect of the invention relates to a method for making a composition containing polymer particles.
The composition of the above-mentioned embodiment can be produced, for example, by a production method including emulsifying a reaction liquid containing at least DHHB (component A), monomer X (raw material for the polymer, component B), polyvinyl alcohol (component C), and water, and carrying out a polymerization reaction of the monomers simultaneously with the emulsification or immediately after the emulsification. In this production method, after emulsification of the reaction liquid, the composition, which is the final product, can be obtained without substantially diluting the emulsified reaction liquid with water or the like.

For example, in the manufacturing method of a polymer particle-containing composition, an oily mixture containing an oil-soluble component such as DHHB and a monomer is dropped into an aqueous solvent such as water to disperse it. However, the manufacturing method of this embodiment does not need to include a step of substantial dilution by such dispersion. Here, the "substantial dilution step" means a step of adding water in an amount of 100% by mass or more (preferably 50% by mass or more, more preferably 30% by mass or more) relative to the mass of water in the reaction liquid. Specifically, after emulsification of the reaction liquid, the emulsified reaction liquid is subjected to a polymerization reaction without going through a dilution step, and a composition containing polymer particles can be obtained without diluting the reaction liquid with water or an aqueous solution between the start and end of the polymerization reaction, except for the addition of the polymerization initiator. In the manufacturing method of this embodiment, the reaction liquid containing water is emulsified in advance, so that the final product can be manufactured without dilution, and therefore a composition with a high polymer particle concentration can be manufactured in one pot.

The reaction liquid refers to a liquid containing a monomer (including at least monomer X) constituting polymer X. The reaction liquid may contain polymer X, but means a liquid in which at least a portion (for example, 10% by mass or more, preferably 50% by mass or more) of the monomer remains unpolymerized. The reaction liquid at the time of emulsification may not contain polymer X. On the other hand, by containing polymer X in the reaction liquid, the conversion rate of the monomer to polymer can be improved and the incorporation of DHHB into the polymer particles can be promoted. When polymer X is contained, the content of polymer X in the reaction liquid before the start of emulsification is preferably 1.0% by mass to 20% by mass, more preferably 5.0% by mass to 15% by mass, and even more preferably 8.0% by mass to 12% by mass, based on the total mass of the monomer constituting polymer X and polymer X.

The reaction liquid may be prepared, for example, by mixing the materials before the polymerization reaction so that the content of the monomers constituting polymer X is 1.5 to 3.9 times (preferably 2 to 3.5 times) the content of DHHB (component A) and the content of water is 10 to 15 times (preferably 12 to 15 times) the content of DHHB (component A). Furthermore, polyvinyl alcohol may be added in an amount of preferably 1 to 20% by mass, more preferably 2 to 10% by mass, based on the total amount of monomers constituting polymer X used.

In the manufacturing method of this embodiment, the final product composition can be obtained in one pot without substantial dilution. The mass ratio of DHHB (component A), the monomer constituting polymer X, polyvinyl alcohol (component C), and water in the reaction liquid may be determined based on the mass ratios of component A, polymer X (component B), component C, and water in the final product composition, as well as DHHB (component A), taking into consideration the incorporation rate of DHHB (component A) into the composition or the conversion rate of monomer to polymer. If a polymerization reaction is carried out simultaneously during the emulsification stage of the reaction liquid, a polymerization initiator may be added to the reaction liquid.

The reaction liquid is preferably prepared by a procedure that includes dissolving DHHB (component A) in a monomer that constitutes polymer X, such as styrene, to prepare an oily mixture, and then mixing this with an aqueous solution in which polyvinyl alcohol (component C) is dissolved in water. When a polymerization initiator is added, it may be added to the oily mixture, the aqueous solution, or a solution in which both are mixed, depending on the type of polymerization initiator.

The reaction liquid is preferably substantially free of ethanol. By making the reaction system substantially free of ethanol, the conversion rate of monomers (e.g., styrene monomer, etc.) to polymer is improved, making purification after the polymerization reaction easier or unnecessary. Here, "substantially free" means that ethanol may be contained in an amount that does not significantly affect the efficiency of the polymerization reaction. For example, ethanol may be contained in an amount that does not require the establishment of a new purification step or a change in the purification method after the polymerization reaction, compared to the case where a reaction mixture containing no ethanol is used. Preferably, the reaction liquid is free of ethanol, and the polymerization reaction is carried out in an ethanol-free reaction liquid.

A surfactant (emulsifier) may be added to the reaction solution to further stabilize the polymerization reaction. Examples of surfactants include sodium dodecyl sulfate, sodium dodecylbenzene sulfate, sodium pentadecane sulfate, N-dodecyl-N,N,N-trimethylammonium bromide, N-cetyl-N,N,N-trimethylammonium bromide, hexadecyltrimethylammonium chloride, and Triton X-100. However, the polymerization reaction in the manufacturing method of this embodiment can proceed stably without adding a surfactant. Therefore, the manufacturing method of this embodiment can produce a polymer particle-containing composition that does not contain a surfactant and is suitable for use as a cosmetic.

The above emulsification can be performed by stirring. Strong stirring is preferable for the reaction solution for emulsification. When stirring is performed in conjunction with the preparation of the reaction solution, the rotation speed can be changed appropriately taking into consideration the scattering of the reaction solution, but the final rotation speed for strong stirring should be 3000 rpm or more, preferably 4000 rpm or more, and more preferably 5000 rpm or more. The stirring time should be 1 minute or more, preferably 5 minutes or more, and more preferably 8 minutes or more. Preferably, stirring is performed for 10 minutes or more at 6000 rpm or more. Stirring can be performed using a stirrer (e.g., mixer, homomixer, homogenizer, etc.) that is capable of high-speed stirring at 6000 rpm or more and is capable of mixing and emulsifying water and oil.

The polymerization reaction can be initiated, for example, by adding a polymerization initiator, raising the temperature, or both. The polymerization reaction temperature depends on the monomer or polymerization initiator used, but is preferably 50 to 100°C, more preferably 60 to 90°C, and even more preferably 70 to 85°C. For example, the reaction liquid may be prepared at room temperature and then heated to the polymerization reaction temperature. At the start of the polymerization reaction, particularly when the polymerization initiator is added to start the polymerization reaction, the reaction may be carried out in an air atmosphere, but from the viewpoint of improving the conversion rate of the monomer to the polymer, it is preferable to carry out the reaction in a vacuum or in an inert gas atmosphere. An inert gas may be blown into the reaction liquid. Examples of the inert gas include nitrogen gas, helium gas, and argon gas.

In the polymerization reaction, the reaction liquid may be stirred. The rotation speed during stirring is preferably 10 to 10,000 rpm, more preferably 50 to 1,000 rpm, and even more preferably 80 to 500 rpm. In order to improve the conversion rate from monomer to polymer, stirring at 80 to 200 rpm is particularly preferred.

The reaction time for the polymerization reaction is usually 30 minutes to 24 hours, and preferably 1 hour to 6 hours.

The polymerization reaction is preferably carried out in the presence of a polymerization initiator. It is also preferable to start the reaction by adding a polymerization initiator. In other words, it is preferable to add a polymerization initiator to the reaction liquid after emulsification without including a polymerization initiator in the reaction liquid before emulsification. At the same time, the reaction liquid may be heated as described above.

The polymerization initiator may be dissolved in a solvent such as water or ethanol and added to the reaction liquid as a solution, or the polymerization initiator may be added as is in the form of a solid or liquid form. As mentioned above, it is not preferable to dilute the emulsified reaction liquid, and it is preferable to use the minimum amount of solvent when dissolving in a solvent, and it is more preferable to add the polymerization initiator as is to the emulsified reaction liquid. The total amount of polymerization initiator to be added may be added in one go, or may be added in multiple portions (for example, two times). The polymerization initiator added in this case may be a radical polymerization initiator, and is preferably a cationic radical polymerization initiator.

In the manufacturing method of this embodiment, the polymerization reaction may be carried out after emulsification of the reaction liquid, or may proceed simultaneously with the emulsification stage of the reaction liquid, but it is preferable to carry out the polymerization reaction after emulsification of the reaction liquid. In an air atmosphere, polymerization reaction at the emulsification stage of the reaction liquid may cause problems such as too much oxygen entering the reaction liquid due to bubbles generated by strong stirring, preventing polymerization by radicals from proceeding and reducing the conversion rate of monomer to polymer. Therefore, when emulsifying the reaction liquid and polymerizing the reaction liquid simultaneously, it is preferable to use an apparatus capable of carrying out the reaction under a vacuum or inert gas atmosphere from which oxygen has been removed in advance.

The polymerization initiator used in the manufacturing method of this embodiment can be selected according to the monomer used. When a monomer containing a carbon-carbon double bond, such as styrene or methyl methacrylate, is used, a radical polymerization initiator may be used. The radical polymerization initiator is not particularly limited, but for example, a nonionic radical polymerization initiator, a cationic radical polymerization initiator, an anionic radical polymerization initiator, or an amphoteric radical polymerization initiator can be used. Among these, a cationic radical polymerization initiator is preferred. In particular, a cationic radical polymerization initiator that bonds to the polymer generated during the polymerization reaction is preferred. By using such a cationic radical polymerization initiator, a cationic functional group is introduced into the polymer X, and polymer particles whose surfaces are covered with positive charges can be formed. Polymer particles whose surfaces are covered with charges are less likely to aggregate due to electrical repulsion between the particles, and the stability over time of the polymer particle-containing composition can be improved. In addition, by being positively charged, as described above, the particles are more easily adsorbed to the skin and hair, improving their suitability as cosmetics.

Cationic radical polymerization initiators include, but are not limited to, 2,2'-[diazene-1,2-diylbis(propane-2,2-diyl)]bis(1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium)=ditrifluoromethanesulfonate (ADIP), 2,2'-[diazene-1,2-diylbis(propane-2,2-diyl)]bis(1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium)=dichloride (ADI It is preferable to use one or more selected from the group consisting of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50, Fujifilm Wako Pure Chemical Industries), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044, Fujifilm Wako Pure Chemical Industries), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (VA-061, Fujifilm Wako Pure Chemical Industries).

Another example of the cationic radical polymerization initiator is a cationic radical polymerization initiator represented by formula (I). For further details on the cationic radical polymerization initiator represented by formula (I), see, for example, JP 2017-051113 A. The contents of this document are incorporated herein by reference. Specific examples of the cationic radical polymerization initiator represented by formula (I) include the above-mentioned ADIP or ADIP-Cl. By using ADIP or ADIP-Cl, the polymer particles of this embodiment can be prepared under milder reaction conditions, and the decrease in the storage stability of the polymer particles due to damage caused by heating during the preparation of the polymer particles can be suppressed. In addition, by using ADIP or ADIP-Cl, the polymer particles can be prepared under milder reaction conditions as described above, which can contribute to reducing the environmental load during synthesis.

[Wherein,
Y represents a single bond or CR ⁸⁵ ;
Z represents a single bond or CR ⁸⁶ ;
R ⁷² , R ⁷³ , R ⁷⁵ , R ⁷⁶ , R ⁷⁷ , R ⁷⁸ , R ⁸⁵ and R ⁸⁶ are each independently selected from the group consisting of a hydrogen atom, C _1-6 alkyl, C _1-6 alkoxy, C _1-6 alkylcarbonyl, phenyl and hydroxy, wherein said C _1-6 alkyl, C _1-6 alkoxy, C _1-6 alkylcarbonyl and phenyl may be further substituted with 1 or 2 substituents selected from the group consisting of C _1-6 alkyl, C _1-6 alkoxy, C _1-6 alkylcarbonyl, phenyl and hydroxy; R ⁷² and R ⁷³ may further each independently represent adamantyl, or C _1-6 alkyl substituted with Si(OCH ₃ ) ₂ (CH ₃ ); or R ⁷⁵ and R ⁷⁶ or R ⁷⁷ and R ⁷⁸ together represent -(CH ₂ ) _3-5 - may be formed,
R ⁸¹ , R ⁸² , R ⁸³ , and R ⁸⁴ are substituents selected from the group consisting of C _1-4 alkyl, C _1-4 alkylcarbonyl, and C _1-3 alkoxy, wherein the C _1-4 alkyl is optionally substituted with one C _1-3 alkoxy group; and R ⁷¹ and R ⁷⁴ are each independently a C _1-3 alkyl group, and X _f ^- is a counter anion.

The "counter anion" in the cationic radical polymerization initiator represented by formula (I) is not particularly limited as long as it is an anion that is commonly used as a counter anion for organic compounds in the technical field of organic chemistry, and includes, for example, halide anions (chloride ion, bromide ion, fluoride ion, iodide ion), conjugate bases of organic acids (e.g., acetate ion, citrate ion, trifluoroacetate ion), nitrate ion, sulfate ion, carbonate ion, etc. Counter anions preferred in the present invention include, for example, trifluoromethanesulfonate ion (triflate), chloride ion, nitrate ion, etc. Among these, chloride ion, acetate ion, or citrate ion are preferred, and chloride ion is more preferred, from the viewpoints of improving the stability over time of the composition produced, increasing the yield of the particles when preparing the polymer particles, and improving the production cost.

The cationic radical polymerization initiator preferably has a residue that becomes a substituent of polymer X through a polymerization reaction. Examples of the residue of the cationic radical polymerization initiator that becomes part of polymer X include the following residues.

The amount of cationic radical polymerization initiator used may be 0.01 mol% or more relative to the total molar amount of the monomers used, and an appropriate amount can be selected within the range of concentrations at which radical synthesis proceeds. For example, a polymerization initiator of 0.1 mol% or more, preferably 1 mol% or more, and 10 mol% or less, preferably 5 mol% or less can be used.

Furthermore, in the polymerization reaction in the manufacturing method of this embodiment, an oil-soluble polymerization initiator may be used together with the cationic radical polymerization initiator as necessary. Examples of the oil-soluble polymerization initiator include azobisisobutyronitrile (AIBN, CAS RN: 78-67-1), 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, CAS RN: 4419-118), etc., and one or more selected from these oil-soluble polymerization initiators are preferable. In addition, as the oil-soluble polymerization initiator, one that can generate radicals even at low temperatures is preferable, and for example, V-65 is preferable. By using an oil-soluble polymerization initiator in combination, the conversion rate from monomers (e.g., styrene monomer, etc.) to polymers is improved. However, in the polymerization reaction in the manufacturing method of this embodiment, a sufficient conversion rate can be obtained even if an oil-soluble polymerization initiator is not used.

The method for producing a composition containing a branched polymer as polymer X may further include a reaction for further crosslinking the polymer obtained by the above polymerization reaction. The crosslinking may proceed simultaneously with the polymerization reaction.

Furthermore, by the polymerization reaction in the manufacturing method of this embodiment, most of the DHHB (component A) in the reaction solution is incorporated into the polymer particles produced, resulting in a high DHHB content. The content of component A in the polymer particle composition relative to the content of component A in the reaction solution is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. Since DHHB is not soluble in water, DHHB that is not incorporated into the polymer particles precipitates as a solid on the walls of the reaction vessel, etc., and can be easily removed.

In the manufacturing method of this embodiment, the conversion rate from monomer to polymer by the polymerization reaction is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

The manufacturing method of this embodiment may include a purification step to remove, for example, DHHB or unreacted monomers that do not constitute the polymer particles. On the other hand, the manufacturing method of this embodiment can be carried out without a purification step by optimizing the mass ratio of DHHB (component A), monomers that constitute polymer X, polyvinyl alcohol (component C), and water in the reaction solution.

<Uses of the polymer particle-containing composition>
The composition of the present disclosure can be used, for example, as a cosmetic, a quasi-drug, a pharmaceutical, or a raw material thereof. For use as a cosmetic, the composition of the present disclosure can be blended with, as necessary, the following components, for example, within a range that does not substantially impair the effects of the present invention:
Liquid fats and oils such as olive oil, camellia oil, macadamia nut oil, castor oil, etc.; solid fats and oils; waxes such as carnauba wax, candelilla wax, jojoba oil, beeswax, lanolin, etc.; higher alcohols such as stearyl alcohol, cetanol, behenyl alcohol, isostearyl alcohol, etc.; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, etc.; hydrocarbon oils such as liquid paraffin, paraffin, volatile isoparaffin, petrolatum, ceresin, microcrystalline wax, squalane, etc.; ester oils such as isopropyl myristate, 2-octyldodecyl myristate, cetyl 2-ethylhexanoate, diisostearyl malate, etc.; methylpolysiloxane, methylphenylpolysiloxane, Silicone oils or crosslinked silicones such as lysiloxane, methylhydrogenpolysiloxane, cyclomethicone, amino-modified or polyether-modified silicone oils; moisturizing agents such as glycerin, propylene glycol, dipropylene glycol, 1,3-butylene glycol, polyethylene glycol, sorbitol, sodium 2-pyrrolidone-5-carboxylate, and sodium hyaluronate; water-soluble polymers such as cationic polysaccharides such as cationic cellulose, cationic guar gum, and cationic locust bean gum, synthetic cationic polymers such as polyquaternium-7, and amphoteric polymers such as polyquaternium-39; trichlorocarbanilide, sulfur, zinc pyrithione, isopropyl methyl pheno anti-dandruff agents such as piroctone olamine; thickeners such as plant-based thickeners, microbial-based thickeners, animal-based thickeners, cellulose-based thickeners, starch-based thickeners, alginic acid-based thickeners, vinyl polymers, and high molecular weight polyethylene glycols; viscosity regulators; anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, opacifiers; sequestering agents; ultraviolet absorbers; antioxidants; preservatives such as methylparaben, ethylparaben, propylparaben, phenoxyethanol, sodium benzoate, 1,2-octanediol, and methylisothiazolinone; mica, talc, kaolin, calcium carbonate, magnesium carbonate, anhydrous silicic acid, aluminum oxide, barium sulfate, red iron oxide, yellow iron oxide, Powder components such as black iron oxide, chromium oxide, ultramarine, Prussian blue, carbon black, titanium dioxide, zinc oxide, titanium mica, fish scale foil, bismuth oxychloride, boron nitride, photochromic pigments, synthetic fluorine phlogopite, iron-containing synthetic fluorine phlogopite, fine particle composite powder, etc.; pigments such as Red No. 106, Orange No. 205, Yellow No. 4, Green No. 3, Blue No. 1, etc.; lower alcohols, polyhydric alcohols, sugars, amino acids, organic amines, polymer emulsions, various extracts, blood circulation promoters, local stimulants, hair follicle activators, antiandrogenic agents, antiseborrheic agents, keratolytic agents, bactericides, antioxidants, antioxidant assistants, anti-inflammatory agents, whitening agents, anti-wrinkle agents, astringents, antioxidants, active oxygen removers, skin nutrients, vitamins, hair growth agents such as herbal extracts, pH adjusters, fragrances, etc. These can be appropriately mixed as necessary and manufactured by conventional methods according to the desired dosage form.

For use as a cosmetic, the composition of the present disclosure may contain an aqueous alcohol in a concentration range used for antibacterial purposes in cosmetics. Examples of aqueous alcohol include ethanol, 1,2-hexanediol, 1,2-pentanediol, 1,3-butanediol, glycerin, and dipropylene glycol. For antibacterial purposes, the aqueous alcohol may be used at a concentration that reaches the minimum inhibitory concentration (MIC) (J Soc Cosmet Chem Japan 46 (2012) 295-300. https://doi.org/10.5107/sccj.46.295.). On the other hand, it is preferable to use the aqueous alcohol at a concentration that maintains the stability of the polymer particles and does not cause leakage of DHHB.

The composition of this aspect can be manufactured as a cosmetic, quasi-drug, pharmaceutical, or raw material thereof according to a method that corresponds to the selected dosage form and form. For example, when the composition of the present disclosure is manufactured as a cosmetic, quasi-drug, or pharmaceutical, any one or more of the above-mentioned ingredients may be added in the manufacturing process of the composition of this aspect described above, or any one or more of the above-mentioned ingredients or a solvent such as water or ethanol may be added after the composition of this aspect is manufactured as described above. At least in the manufacturing of the composition of this aspect described above, it is preferable to add a solvent after the polymerization reaction that results in stable polymer particles. Typically, the composition is manufactured by dissolving the above-mentioned essential ingredients and necessary optional ingredients in a solvent such as water. Examples of the product form of the cosmetic include emulsion, lotion, cream, sunscreen, ointment, powder, sheet, or spray. In one embodiment, the cosmetic is a cosmetic composition for skin. In another embodiment, the cosmetic is a cosmetic composition for hair.

In addition, when the composition of this embodiment is produced as a raw material for cosmetics, quasi-drugs, or pharmaceuticals, the composition of this embodiment may be added to an aqueous medium containing water, liquid oils and fats, surfactants, thickeners, etc., and further processing such as heating, cooling, or stirring may be performed as necessary to produce the cosmetics, quasi-drugs, or pharmaceuticals.

The present invention will be explained in more detail below with reference to examples. The materials, reagents, amounts and proportions of substances, and operations shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

In the following examples and comparative examples, the polyvinyl alcohol (PVA) used was PVA manufactured by Nippon Vinyl Acetate & Poval Co., Ltd. (product name: JMR-3H, degree of saponification: 78 mol%, average degree of polymerization: 110). The 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate (DHHB) used was DHHB manufactured by Tokyo Chemical Industry Co., Ltd. The homomixer used was a Laborution Homomixer MARK II 2.5 model (manufactured by Primix Corporation).

<Examples 1 to 3 and Comparative Examples 1 and 2>
Example 1: Synthesis of cationic styrene-based polymer particles SY032 containing UV absorber DHHB 15 g of DHHB was dissolved in 45 g of styrene. Then, 20 g of an aqueous solution in which 4.0 g of PVA was dissolved was placed in a beaker, and 170 g of pure water was added. The aqueous PVA solution was set in a homomixer, and a styrene solution containing DHHB was added while stirring at 2000 rpm. The resulting reaction solution was emulsified by stirring for 10 minutes at a stirring speed of 6000 rpm. The emulsified reaction solution was transferred to a separable flask (capacity 300 mL) with a baffle after blowing argon gas into the entire solution for 10 minutes. The mixture obtained by adding 470 mg of VA-044 to the above reaction solution was heated to 80 ° C. with a mantle heater while stirring at 120 rpm with a mechanical stirrer. After 2 hours of reaction, an additional 470 mg of VA-044 was added, and the reaction was continued for another 2 hours to obtain a polymer particle composition (SY032) as a reaction product.

Example 2: Synthesis of cationic styrene-based polymer particles SY034 containing UV absorber DHHB (when V-50 is used as initiator)
15 g of DHHB was dissolved in 45 g of styrene. Then, 20 g of an aqueous solution in which 4.0 g of PVA was dissolved was placed in a beaker, and 170 g of pure water was added. The PVA aqueous solution was set in a homomixer, and the styrene solution containing DHHB was added while stirring at 2000 rpm. The resulting reaction solution was emulsified by increasing the stirring speed to 6000 rpm and stirring for 10 minutes. The emulsified reaction solution was transferred to a separable flask (capacity 300 mL) with a baffle after blowing argon gas into the entire solution for 10 minutes. The mixture obtained by adding 470 mg of V-50 to the above reaction solution was heated to 80 ° C. with a mantle heater while stirring at 120 rpm with a mechanical stirrer. After 2 hours of reaction, an additional 470 mg of V-50 was added, and the reaction was continued for another 2 hours, to obtain a polymer particle composition (SY034) as a reaction product.

Comparative Example 1: Synthesis of cationic butyl acrylate polymer particles SY036 containing UV absorber DHHB 15 g of DHHB was dissolved in 45 g of tert-butyl acrylate. Then, 20 g of an aqueous solution in which 4.0 g of PVA was dissolved was placed in a beaker, and 170 g of pure water was added. The PVA aqueous solution was set in a homomixer, and a tert-butyl acrylate solution containing DHHB was added while stirring at 2000 rpm. The resulting reaction solution was further emulsified by increasing the stirring speed to 6000 rpm and stirring for 10 minutes. The emulsified reaction solution was transferred to a separable flask (capacity 300 mL) with a baffle after blowing argon gas into the entire solution for 10 minutes. The mixture in which 470 mg of VA-044 was added to the above reaction solution was heated to 80 ° C. with a mantle heater while stirring at 120 rpm with a mechanical stirrer. After 2 hours of reaction, an additional 470 mg of VA-044 was added, and the reaction was continued for another 2 hours to obtain a polymer particle composition (SY036) as a reaction product.

Example 3: Synthesis of cationic methyl methacrylate polymer particles SY038 containing UV absorber DHHB 15 g of DHHB was dissolved in 45 g of methyl methacrylate. Then, 20 g of an aqueous solution in which 4.0 g of PVA was dissolved was placed in a beaker, and 170 g of pure water was added. The PVA aqueous solution was set in a homomixer, and the methyl methacrylate solution containing DHHB was added while stirring at 2000 rpm. The resulting reaction solution was further emulsified by increasing the stirring speed to 6000 rpm and stirring for 10 minutes. The emulsified reaction solution was transferred to a separable flask (capacity 300 mL) with a baffle after blowing argon gas into the entire solution for 10 minutes. The mixture in which 470 mg of VA-044 was added to the above reaction solution was heated to 80 ° C. with a mantle heater while stirring at 120 rpm with a mechanical stirrer. After 2 hours of reaction, an additional 470 mg of VA-044 was added, and the reaction was continued for another 2 hours to obtain a polymer particle composition (SY038) as a reaction product.

Comparative Example 2: Synthesis of cationic styrene-based polymer particles SY039 containing UV absorber DHHB 15 g of DHHB was dissolved in 45 g of styrene. Then, 20 g of an aqueous solution in which 4.0 g of PVA was dissolved in a separable flask (capacity 300 mL) with a baffle was placed in a beaker, and 170 g of pure water was added. A styrene solution containing DHHB was further added. While stirring at 450 rpm, argon gas was blown into the entire reaction solution obtained for 10 minutes, and 470 mg of VA-044 was added. The mixture was heated to 80 ° C. with a mantle heater while stirring at 450 rpm with a mechanical stirrer. After 2 hours of reaction, an additional 470 mg of VA-044 was added, and the reaction was continued for another 2 hours to obtain a polymer particle composition (SY039) as a reaction product.

The polymer particle compositions (reaction products) obtained in Evaluation Examples 1 to 3 and Comparative Examples 1 and 2 were each transferred from the reaction vessel to a measurement vessel [microtube (material: polypropylene, capacity: 1.5 mL, manufactured by Eppendorf Co., Ltd.)] and dried with dry heat to calculate the dry mass of each polymer particle composition.
The DHHB content of each polymer particle composition was measured as follows, with reference to "Hygienic Test Methods - Commentary 2015" (edited by the Pharmaceutical Society of Japan, Kanehara Publishing (2015)). The polymer particle composition was centrifuged (20400G, 10 minutes) to recover the precipitate. After diluting the recovered material with tetrahydrofuran, DHHB was extracted with chloroform and quantitatively analyzed by high performance liquid chromatography (HPLC). DHHB was detected using the absorbance at 350 nm as an index.

The average particle size of the polymer particles contained in the polymer particle composition was measured by dynamic light scattering using a Zetasizer Nano ZSP (Malvern Instruments). PdI was measured using a Zetasizer Nano ZSP (Malvern Instruments). The average zeta potential was measured using a Zetasizer Nano ZSP (Malvern Instruments). All measurements were performed at 25° C., and the viscosity of water was 0.89 mPa·s ⁻¹ and the relative dielectric constant was 78.5. Henry's function (1.5) was used to calculate the zeta potential.
The stability over time was evaluated by transferring a sample immediately after production into a glass bottle, storing it at room temperature for 2 weeks, and then evaluating the stability over time according to the following criteria.
(Evaluation criteria)
A: When shaken 5 times or less, no visual change from immediately after manufacture is observed. B: When shaken 5 times or more but not more than 15 times, no visual change from immediately after manufacture is observed. C: When shaken more than 15 times, a visual change from immediately after manufacture is observed.

Table 1 shows the amounts of ingredients and manufacturing processes used to manufacture the compositions of Examples 1 to 3 and Comparative Examples 1 and 2, as well as the measurement results of the resulting compositions.

In Table 1, each value was calculated using the following formula.
*1: Solid content concentration (mass%) of polymer particle composition = [dry mass of polymer particle composition] / [mass of polymer particle composition] x 100
*2: Solid content yield (mass%) of polymer particle composition = [dry mass of polymer particle composition] / [total mass of charged DHHB + charged monomer + charged PVA] × 100
*3: DHHB content (mass%) in polymer particle composition=[mass of DHHB in the precipitate after centrifugation of polymer particle composition]/[mass of polymer particle composition]×100
*4: DHHB incorporation rate (mass%) in polymer particle composition = [mass of DHHB in the precipitate after centrifugation of polymer particle composition] / [mass of DHHB charged] x 100
*5: Polymer conversion rate (mass%)=[mass obtained by subtracting the mass of PVA charged and the mass of DHHB in the precipitate after centrifugation of the polymer particle composition from the dry mass of the polymer particle composition]/[mass of monomer charged]×100
*6: Ratio of DHHB/polymer in polymer particle composition (mass%)=[mass of DHHB in the precipitate after centrifugation of polymer particle composition]/[mass of charged monomer×polymer conversion rate]×100
*7: DHHB content (mass%) in the solid content of the polymer particle composition = [mass of DHHB in the precipitate after centrifugation of the polymer particle composition] / [dry mass of the polymer particle composition] × 100

The content of DHHB in the composition of Example 1 was high at 6.2% by mass, and the stability over time was also good. The content of DHHB in the composition of Example 2 was high at 5.8% by mass, and the stability over time was also good. In Comparative Example 1, tert-butyl acrylate was used as the monomer during production. The content of DHHB in the obtained composition was high at 5.6% by mass, but the stability over time was poor. The content of DHHB in the composition of Example 3 was high at 5.8% by mass, and the stability over time was also good. Although the composition of Comparative Example 2 had excellent stability over time, the content of DHHB in the composition of Comparative Example 2 was 3.8% by mass, which was less than 5.5% by mass. In Comparative Example 2, the production did not include a step of stirring to obtain an emulsion. DHHB precipitated from the reaction solution was found to adhere to the wall of the beaker used, and the uptake rate of DHHB was 63% by mass.

<Examples 11 to 12 and Comparative Example 11>
15 g of DHHB was dissolved in the amount of styrene listed in Table 2. After adding a PVA aqueous solution (2 wt%, 189 g) to a 500 mL polypropylene disposable cup, the styrene solution containing DHHB was slowly added to the PVA aqueous solution while stirring at 2000 rpm. The resulting reaction solution was further emulsified by stirring for 10 minutes at a stirring speed of 6000 rpm. In Example 12 using polystyrene, polystyrene with a weight average molecular weight of 50,000 (Polysciences, Inc. (USA)) was dissolved in styrene monomer overnight at 4° C. while stirring.

Argon gas was blown into the emulsified reaction liquid for 10 minutes, and then the liquid was transferred to a separable flask (volume 300 mL) equipped with a baffle. The temperature of the reaction liquid was then increased, and radical initiator VA-044 (470 mg) dissolved in 1 g of water was added, followed by stirring at 60°C for 4 hours at the rotation speed shown in Table 2. After the reaction was completed, all reaction liquids were cooled to 25°C, and the characteristics were evaluated. The results are shown in Table 2.

Polymer concentration (mass%) of polymer particle composition=solids concentration (mass%) of polymer particle composition−DHHB content (mass%) in polymer particle composition

As can be seen by comparing Comparative Example 11 and Example 12 in Table 2, dissolving polystyrene in styrene monomer before emulsification increased the DHHB content in the polymer particle composition. Considering that it has already been reported that the addition of polystyrene increases the stability of oil droplets (Langmuir. 19 (2003) 4063-4069. https://doi.org/10.1021/la020749i), it is suggested that the incorporation of DHHB is promoted by stabilizing the styrene monomer droplets by the addition of polystyrene. In Example 12, the styrene monomer was almost completely converted to polymer, and DHHB was almost completely incorporated into the particles.

<Reference Example 1>
The polymer particle composition of Reference Example S1 (Table 3) (20 mg) prepared in the same manner as in Example 12 except that polystyrene having a weight average molecular weight of 300,000 (Toyo Styrene Co., Ltd.) was used as the polystyrene was added to a 1.5 mL tube, and ethanol (10% by mass), 2.1,2-hexanediol (5% by mass), 1,2-pentanediol (10% by mass), or 1,3-butanediol (20% by mass) was added. Water was added to the mixture to adjust the final polymer particles (0.05% by mass) and alcohol content. The sample was then incubated at 50°C for 24 hours and centrifuged at 20,400 g for 45 minutes. After centrifugation, the supernatant (150 μL) was diluted with acetonitrile (850 μL).

The positive control was prepared as follows: The polymer particle composition of Reference Example S1 (20 mg) and THF (100 μL) were mixed thoroughly in a 1.5 mL tube. Chloroform (600 μL) was then added and ultrasonicated for 15 minutes. The ultrasonicated sample (10 μL) was diluted with acetonitrile (990 μL). All prepared samples were filtered through a PTFE (polytetrafluoroethylene) membrane filter with a pore size of 0.2 μm.

The DHHB content in the supernatant containing each alcohol and the positive control was measured by HPLC in the same manner as when determining the DHHB content in the polymer particle composition. Based on the HPLC analysis, the relative amount of DHHB in the alcohol aqueous solution was calculated as "(DHHB content in alcohol aqueous solution)/(DHHB content in positive control)". As shown in Figure 1, DHHB was not detected in any of the solutions, indicating that DHHB had not leaked from the polymer particles.

<Reference Example 2>
The polymer particle composition of Reference Example S2 shown in Table 3 was prepared in the same manner as in the preparation of the polymer particle composition of Reference Example S1.
Bleached hair (white hair) was immersed in the polymer particle composition of Reference Example S1, water, and the polymer particle composition of Reference Example S2 for 10 minutes. The treated hair was then washed three times by immersing it in water for 5 minutes to remove excess particles, and dried at room temperature. The dried hair was cut into 1 cm pieces for observation using a scanning electron microscope (SEM, Nova NanoSEM 450, FEI, USA), and SEM measurements were performed. Each dried hair sample was directly attached to carbon tape and observed with SEM. Observation was performed at an acceleration voltage of 500 V and a magnification of 2000 times (Figures 2A-C) or 8000 times (Figure 2D). The obtained images were analyzed using NaviCam (Sony Computer Science Laboratories, Inc.).

2 shows SEM images of hair treated with water (FIG. 2A), the polymer particle composition of Reference Example S1 (FIG. 2B), and the polymer particle composition of Reference Example S2 (FIG. 2C), and FIG. 2D shows an enlarged image of the square frame shown in FIG. 2B. The characteristic scale-like surface structure of hair can be seen in FIGS. 2A-D, and particles can be seen over a wide area of the hair surface in FIGS. 2B and 2D. The particle diameter measured from the 10 particles observed in FIG. 2D was 263±19 nm, which was almost the same as the particle diameter obtained by measurement using the dynamic light scattering method. On the other hand, no particle structure was observed in FIGS. 2A and 2C. That is, it was confirmed that the polymer particles (cationic) in the polymer particle composition of Reference Example S1 were strongly adsorbed to hair, and the polymer particles (anionic) in the polymer particle composition of Reference Example S2 were not adsorbed to hair.

Claims

Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A composition comprising: component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher; and component C: polymer particles containing polyvinyl alcohol; and water,
The average particle size of the polymer particles is 350 nm or less,
The polydispersity index PdI of the polymer particles as measured by a dynamic light scattering method is 0.2 or less;
The content of component A in the composition is 5.5 mass% or more.
The composition according to claim 1, wherein the content of component A is 26 to 67 mass% relative to the content of component B.
The composition of claim 1, wherein the monomer is styrene or methyl methacrylate.
The composition according to claim 1, wherein component B is a polymer having a cationic functional group.
The composition according to claim 1, wherein the content of component A in the polymer particles is 20% by mass or more.
The composition of claim 1, which is substantially free of surfactants.
Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A composition comprising: component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher; and component C: polymer particles containing polyvinyl alcohol, wherein the polymer particles have an average particle size of 350 nm or less;
The content of component A is 26 to 67% by mass relative to the content of component B,
The composition, wherein the polymer particles have a polydispersity index PdI of 0.2 or less as measured by a dynamic light scattering method.
The composition of claim 7, wherein the monomer is styrene or methyl methacrylate.
The composition according to claim 7, wherein component B is a polymer having a cationic functional group.
Component A: 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate,
A method for producing a composition comprising component B: a polymer containing a repeating unit derived from a monomer capable of forming a homopolymer having a glass transition temperature of 80° C. or higher, and component C: polymer particles containing polyvinyl alcohol, the method comprising the steps of:
The production method includes a step of emulsifying a reaction liquid containing at least component A, the monomer, component C, and water, and a step of carrying out a polymerization reaction of the monomer simultaneously with or after the emulsification.
The method according to claim 10, wherein the total mass of the monomers contained in the reaction solution before the start of the polymerization reaction is 1.5 to 3.9 times the total mass of component A, and the total mass of the water is 10 to 15 times the total mass of component A.
The method of claim 10, wherein the reaction solution is not diluted between the start and completion of the polymerization reaction.
The method of claim 10, wherein the emulsification is carried out by stirring for 10 minutes or more at 6000 rpm or more.
The method according to any one of claims 10 to 13, wherein the polymerization reaction is carried out in the presence of a polymerization initiator.
The manufacturing method according to any one of claims 10 to 13, wherein the reaction liquid before emulsification does not contain a polymerization initiator, and further includes a step of adding a polymerization initiator to the reaction liquid after the emulsification.
The method of claim 14, wherein the polymer particles include a polymer having the repeating units and a residue of the polymerization initiator.
The method according to claim 16, wherein the residue is a residue having a cationic functional group.
The method according to any one of claims 10 to 13, wherein the reaction liquid before emulsification contains component B.
The method of claim 18, wherein the monomer is styrene and component B is polystyrene.
The method according to any one of claims 10 to 13, wherein the composition is a composition according to any one of claims 1 to 9.
The method according to any one of claims 10 to 13, wherein the content of component A in the composition relative to the content of component A in the reaction liquid is 70 mass% or more.