Cosmetic composition

Abstract

This cosmetic composition contains a crosslinked compound obtained by crosslinking a crosslinkable polymer having a substituted or unsubstituted lophine group at least at one terminal of a skeleton polymer by means of bonding between the lophine groups. The fluidity of the cosmetic composition is reversibly changed by irradiation with light having a prescribed wavelength.

Description

Cosmetic composition

[0001] The present invention relates to a cosmetic composition.

[0002] Photoresponsive compounds whose fluidity can be reversibly changed by light irradiation are known. For example, Patent Document 1 discloses a crosslinked polymer formed by crosslinking a precursor polymer having a lophine group introduced at least one end of a backbone polymer, the lophine groups of the precursor polymer having a structure in which the lophine groups are intermolecularly crosslinked by covalent bonds, and the crosslinks are cleaved by light stimulation, allowing the polymer to reversibly change from a solid state to a liquid state. Patent Document 1 also describes the application of the disclosed crosslinked polymer to adhesives and the like in solvent-free systems.

[0003] JP 2017-149793 A

[0004] The application of the above-mentioned photoresponsive crosslinked polymer has been studied to some extent in the past, as described in Patent Document 1. However, the studies have been limited to the application of the polymer in a solvent-free system. There has been no study to date on preparing a solvent-based composition containing the above-mentioned crosslinked polymer and providing it as, for example, a photoresponsive cosmetic composition.

[0005] In view of the above, an object of one aspect of the present invention is to provide a cosmetic composition that exhibits photoresponsiveness by utilizing a crosslinkable polymer having a lophine group introduced at the end.

[0006] One aspect of the present invention for solving the above-mentioned problems is a cosmetic composition that contains a crosslinked compound formed by crosslinking a crosslinkable polymer having a substituted or unsubstituted lophine group at at least one end of a backbone polymer through bonding between the lophine groups, and whose fluidity is reversibly changed by irradiation with light of a predetermined wavelength.

[0007] According to one aspect of the present invention, a cosmetic composition exhibiting photoresponsiveness can be provided by utilizing a crosslinkable polymer having a lophine group introduced at the end.

[0008] 1 is a graph showing the results of viscoelasticity evaluation for Example 1-1. FIG. 2 is a graph showing the results of viscoelasticity evaluation for Example 1-2. FIG. 3 is a graph showing the results of viscoelasticity evaluation for Example 1-3. FIG. 4 is a graph showing the results of viscosity evaluation for Example 1-8. FIG. 5 is a graph showing the results of viscosity evaluation for Example 1-9. FIG. 6 is a graph showing the results of viscosity evaluation for Example 1-10.

[0009] One embodiment of the present invention is a cosmetic composition that contains a crosslinkable polymer having a substituted or unsubstituted lophine group at at least one end of a backbone polymer, and a crosslinking compound formed by crosslinking the lophine groups through bonding between each other, and that exhibits a reversible change in fluidity upon irradiation with light of a predetermined wavelength.

[0010] The present inventors have conducted extensive research into solvent-based compositions containing compounds (photoresponsive compounds) whose fluidity is reversibly changed by irradiation with light, and have found that a composition containing a crosslinked compound formed by crosslinking a crosslinkable polymer having a substituted or unsubstituted lophine group at at least one end of a backbone polymer through bonding between the lophine groups also exhibits photoresponsiveness as a composition itself. More specifically, the present inventors have found that a composition containing a crosslinked compound formed by crosslinking a crosslinkable polymer having a substituted or unsubstituted lophine group at at least one end of a backbone polymer through bonding between the lophine groups and an oily solvent also exhibits photoresponsiveness as a composition itself. The present inventors have also found that a composition containing such a crosslinked compound and an oily solvent can be provided as a cosmetic composition.

[0011] The cosmetic composition according to this embodiment may be an oil-based composition in which the solvent is essentially an oily solvent, or an emulsion composition in which the solvent contains an oily solvent and an aqueous solvent and the oil phase and the aqueous phase are emulsified. The emulsion composition may be either an oil-in-water emulsion composition or a water-in-oil emulsion composition, with a water-in-oil emulsion composition being preferred.

[0012] As used herein, the term "cosmetic composition" includes cosmetics, quasi-drugs, and personal care products (daily hygiene products) (hereinafter collectively referred to as cosmetics, etc.), and also includes bases for preparing these products. That is, the cosmetic composition according to the present embodiment may be provided as a final product itself, or may be a raw material for preparing a final product. Examples of cosmetics include skin care products such as lotions, emulsions, and serums, which may also be provided in gel form, and makeup cosmetics such as basic cosmetics, lipsticks, lip glosses, foundations, blushes, and eye shadows. Examples of personal care products (daily hygiene products) include sunscreens, body creams, body lotions, hair conditioners, and hand creams.

[0013] As used herein, "photoresponsiveness" refers to a change in properties upon irradiation with light of a predetermined wavelength, particularly a change in fluidity. Furthermore, "change in fluidity" or "change in fluidity" may refer to a property that can be measured as a change in rheological properties related to viscosity, elasticity, and viscoelasticity, or a property that can be evaluated by sensory evaluation of the feel of a substance, such as smoothness, softness, and lack of creaking when touched by a human. The "rheological property" may refer to a change in physical property that can be visually observed by simply flowing a substance in a static state or without the use of a machine, for example, a change between a solid or gel-like state and a liquid or sol-like state. Furthermore, the rheological properties may be measurable changes in elastic moduli such as storage modulus G' (Pa) and loss modulus G" (Pa), viscosity, shear rate (shear strength), and thixotropy index, as well as changes therein over time. Furthermore, "changes in fluidity" or "changes in fluidity" may be properties that can be evaluated by sensory evaluation of the feel of the cosmetic composition, such as smoothness, softness, and absence of squeaking, when the cosmetic composition is touched or applied by a person.

[0014] "Photoresponsive" may also include the property of changing color when irradiated with light of a specific wavelength. The color change may be noticeable when used in the usual way by a person, such as with cosmetics.

[0015] <Photoresponsive Compound> The photoresponsive compound used in this embodiment may be a compound capable of reversibly changing between a crosslinkable polymer having a lophine group (2,4,5-triphenylimidazole group) at at least one end of the backbone polymer and a crosslinked compound formed by crosslinking the crosslinkable polymer. The backbone polymer (main chain polymer) in the crosslinkable polymer may be polysiloxane, specifically polydimethylsiloxane (PDMS), polymethylhydrosiloxane (PMHS), or the like. Furthermore, the backbone polymer is not limited to a linear polymer, but may have a 3- to 5-branched structure branched from a central core. A structure with three or more branches is preferred, and a 3-branched structure is more preferred, since the crosslinkable polymer can form a three-dimensional network when crosslinked. When the backbone polymer has a branched structure, the central core preferably contains a carbon atom or a benzene ring, and more preferably contains a benzene ring, since this increases the chemical stability of the photoresponsive compound.

[0016] The crosslinkable polymer can be obtained, for example, by introducing a functional group containing a lophine group into a skeleton polymer (main chain polymer). In this case, it is preferable that the skeleton polymer before the introduction of the lophine group has a hydrosilane at its end, and that the hydrosilane is reacted with a compound containing a lophine group and a vinyl group. The functional group containing a lophine group used in the reaction may have, for example, the following formula (1):

[0017] In formula (1), R １ , R ２ and R ３may each independently represent a hydrogen atom (unsubstituted) or a group selected from the group consisting of a halogen atom, a nitro group, a linear or branched alkyl group having from 1 to 5 carbon atoms, a linear or branched alkenyl group having from 1 to 5 carbon atoms, an aryl group, a sulfo group, a carboxy group, an ester group, a thioester group, a dithioester group, a carbonate group, a thiocarbonate group, a dithiocarbonate group, a trithiocarbonate group, a carbamate group, a thiocarbamate group, a dithiocarbamate group, an ether group, a hydroxy group, a thiol group, a sulfide group, a disulfide group, a silyl group, an amino group, and an amide group; a1 may represent an integer of from 1 to 4, and a2 and a3 may each independently represent an integer of from 1 to 5.

[0018] Therefore, for example, a photoresponsive compound can be synthesized by reacting a backbone polymer having a hydrosilane group at at least one end with 2-(4-vinyl)phenyl)-4,5-diphenyl-1H-imidazole.

[0019] When the photoresponsive compound used in this embodiment has a branched structure, it preferably has a structural formula represented by formula (2), for example.

[0020] In formula (2), n may be an integer of 2 or more and 1000 or less. Ｓ may each independently be a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. １ , R ２ and R ３may each independently be a hydrogen atom (unsubstituted) or a group selected from the group consisting of a halogen atom, a nitro group, a linear or branched alkyl group having from 1 to 5 carbon atoms, a linear or branched alkenyl group having from 1 to 5 carbon atoms, an aryl group, a sulfo group, a carboxy group, an ester group, a thioester group, a dithioester group, a carbonate group, a thiocarbonate group, a dithiocarbonate group, a trithiocarbonate group, a carbamate group, a thiocarbamate group, a dithiocarbamate group, an ether group, a hydroxy group, a thiol group, a sulfide group, a disulfide group, a silyl group, an amino group, and an amide group, and a1 may be an integer of from 1 to 4, and a2 and a3 may each independently be an integer of from 1 to 5. The branched chains may all have the same structure, or may each independently have different structures.

[0021] In formula (2), n may be 2 or more and 1000 or less as described above, but is preferably 20 or more and 450 or less, and more preferably 40 or more and 250 or less. Furthermore, n may be the same or different between the branched chains. However, it is preferable that n be approximately the same between the branched chains.

[0022] In addition, in formula (2), R Ｓ is preferably a methyl group, in which case the backbone polymer is polydimethylsiloxane (PDMS). In this way, by using polydimethylsiloxane (PDMS) as the backbone polymer, the crosslinkable polymer and the crosslinked compound obtained by crosslinking the crosslinkable polymer become relatively chemically stable, which is preferable in that they are compatible with oil-based solvents (described in detail later) even when a solvent-based cosmetic composition is prepared.

[0023] In the photoresponsive compound represented by formula (2), it is sufficient that at least one of the ends of the branched chain has a lophine group. However, since a significant change in fluidity can be obtained by light irradiation (described in detail later), it is preferable that the crosslinkable polymer has lophine groups at all ends. In addition, the presence or absence of substitution in the lophine group and the type of the substituent may be the same for each branched chain or may be different from each other. However, the lophine group must be unsubstituted, that is, in formula (2), R１ , R ２ , and R ３ is preferably a hydrogen atom.

[0024] Furthermore, the photoresponsive compound represented by formula (2) may more specifically have a structural formula represented by formula (3).

[0025] In formula (3), n may be an integer of 2 or more and 1000 or less. The branched chains may all have the same structure, or may each independently have a different structure.

[0026] The number-average molecular weight Mn of the crosslinkable polymer may be preferably 2,000 or more and 200,000 or less, more preferably 5,000 or more and 100,000 or less, and even more preferably 10,000 or more and 50,000 or less. By setting the number-average molecular weight Mn within the above range, the change in fluidity of the photoresponsive compound due to light irradiation is more pronounced, and this change can be reflected in the cosmetic composition.

[0027] Here, the reversible photoresponsiveness of a photoresponsive compound will be explained using a crosslinked polymer having a structural formula represented by formula (3) as an example. The reversible photoresponsiveness is exhibited when the lophine groups contained in the crosslinked polymer are released from their bonds upon light irradiation and re-bonded upon cessation of light irradiation. Formula (4) shows an example of the reversible change of a crosslinked polymer upon light irradiation and cessation of light irradiation.

[0028]

[0029] In the absence of light irradiation, a crosslinkable polymer forms a multimer (crosslinked compound) by bonding multiple crosslinkable polymers together. At this time, lophine groups of different molecules within the crosslinkable polymer are bonded together, and in some cases, lophine groups within the crosslinkable polymer may also be bonded together. A hexaarylbiimidazole (HABI) group is formed by the covalent bond between the lophine groups. In the above formula (4), in the absence of light irradiation, the crosslinkable polymer having the structural formula represented by formula (3) is crosslinked, forming a crosslinked compound (PDMS-HABI) in which polydimethylsiloxane having a lophine terminal group is crosslinked. Such a crosslinked compound has a relatively low fluidity (also referred to as a low-fluidity state).

[0030] When the crosslinked compound is irradiated with light, the covalent bond between the lophine groups in the hexaarylbiimidazole (HABI) group is released (cleaved), and the crosslink is released. As a result, the crosslinked polymer exists as a monomer, and its fluidity becomes higher than that of the crosslinked compound (also called a high fluidity state). The crosslinked polymer of the monomer in a high fluidity state has a triphenylimidazolyl radical.

[0031] The low fluidity state may be a solid or gel-like state, and the high fluidity state may be a liquid or sol-like state. However, as described above, the "change in fluidity" in this specification may be any change in properties that can be evaluated by changes in measured physical properties or by sensory evaluation. For example, even if a composition is recognized as a liquid or sol-like both before and after light irradiation, if a change in fluidity due to light irradiation (or cessation of irradiation) is confirmed, the state with higher fluidity in the change can be called a high fluidity state, and the state with lower fluidity can be called a low fluidity state. In other words, both the low fluidity state and the high fluidity state may be liquid or sol-like, or both the low fluidity state and the high fluidity state may be solid or gel-like.

[0032] Furthermore, the light that causes a change in the fluidity of the photoresponsive compound as described above may preferably be light in the ultraviolet region, for example, light with a wavelength of 300 nm or more and 400 nm or less, more preferably light with a wavelength of 350 nm or more and 380 nm or less, even more preferably light with a wavelength of 360 nm or more and 370 nm or less, and even more preferably light with a wavelength of 365 nm.

[0033] In this specification, the term "photoresponsive compound" does not refer to the fluid state of the compound described above. In other words, the term "photoresponsive compound" includes compounds in a state where they are irradiated with light of a predetermined wavelength and compounds in a state where they are not irradiated with light of a predetermined wavelength. The term "photoresponsive compound" refers to a crosslinked polymer (high fluidity state), a crosslinked compound (low fluidity state), or a mixture of both.

[0034] In this embodiment, the photoresponsiveness of the above-described photoresponsive compound is also reflected in the cosmetic composition. That is, the fluidity of the cosmetic composition according to this embodiment also changes reversibly upon irradiation with light of a predetermined wavelength.

[0035] The content of the photoresponsive compound, as the content of the crosslinking compound, may be preferably 0.1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass or less, and even more preferably 2.5% by mass or more and 10% by mass or less, relative to the total content of the oily solvent (described below) and the photoresponsive compound. By setting the content of the photoresponsive compound to 0.1% by mass or more, the photoresponsiveness of the cosmetic composition can be more significantly exhibited. For example, when the storage modulus G' (Pa) and / or the loss modulus G" (Pa) are compared between a high fluidity state and a low fluidity state, the difference becomes more significant. Furthermore, by setting the content of the photoresponsive compound to 50% by mass or less, the dissolution state of the crosslinking compound in the solvent can be improved, and a homogeneous cosmetic composition can be obtained.

[0036] Furthermore, the content of the photoresponsive compound, as the content of the crosslinking compound, may be preferably 0.01% by mass or more and 50% by mass or less, more preferably 0.1% by mass or more and 30% by mass or less, relative to the total amount of the cosmetic composition. It may be even more preferably 1% by mass or more and 10% by mass or less. By being 0.01% by mass or more, the photoresponsiveness of the cosmetic composition can be more significantly expressed. By being 50% by mass or less, the dissolution state of the crosslinking compound in the solvent can be improved, and a homogeneous cosmetic composition can be obtained.

[0037] The photoresponsive compound dissolves well in oily solvents. Therefore, when the cosmetic composition according to this embodiment is an oil-based composition, the photoresponsive compound is dissolved entirely in the oil-based composition. Furthermore, when the cosmetic composition according to this embodiment is an emulsion-based composition, the photoresponsive compound is dissolved mainly in the oil phase.

[0038] <Oil-based solvent> The oil-based solvent to be combined with the above-mentioned photoresponsive compound is not particularly limited as long as it is an oil-based solvent that can be used as a component of a cosmetic composition. However, from the viewpoint of being able to well dissolve the photoresponsive compound (crosslinked compound) and prepare a homogeneous composition, it is preferable to contain a low-molecular-weight, non-polar solvent. Note that the term "low-molecular-weight" in this specification does not necessarily have a general meaning, and may vary depending on the solvent, and may refer to the molecular weight size compared between the same solvent type (for example, between silicone oils, between hydrocarbon oils). It is preferable that the low-molecular-weight solvent is a volatile solvent.

[0039] Examples of low-molecular-weight nonpolar solvents include one or more of silicone oil and hydrocarbon oil. The silicone oil is preferably a volatile silicone oil. The silicone oil may be a linear or branched polysiloxane, or a cyclic siloxane, but a linear polysiloxane or a cyclic siloxane is preferred because it can better dissolve the above-mentioned photoresponsive compound. In this specification, a linear polysiloxane refers to a structure in which a hydrogen atom or a methyl group is bonded to a main skeleton that is a siloxane bond (-Si-O-Si-).

[0040] Specific examples of silicone oils include polydimethylsiloxane (PDMS, dimethicone), polymethylhydrosiloxane (PMHS), cyclomethicone, etc. Among these, polydimethylsiloxane (PDMS, dimethicone) is preferred. In addition, when the low-molecular nonpolar solvent is silicone oil, the kinematic viscosity (mm ２ The molecular weight ( / s or cs) is not particularly limited and may be preferably 0.1 to 100, more preferably 0.5 to 50, at 25° C. The number average molecular weight of the silicone oil may be preferably 100 to 2,000, more preferably 200 to 1,000.

[0041] The hydrocarbon oil is preferably a saturated aliphatic hydrocarbon. A volatile hydrocarbon is also preferred. The hydrocarbon oil used as an oil-based solvent may preferably have 5 to 30 carbon atoms, more preferably 10 to 20 carbon atoms. The hydrocarbon oil may be a straight-chain hydrocarbon or a branched hydrocarbon. However, it is preferable that the straight-chain hydrocarbon or the branched hydrocarbon have a group constituting the branched chain with 1 carbon atom (a methyl group). Specific examples of hydrocarbon oils include isododecane, isohexadecane, and hydrogenated polyisobutene. The molecular weight of the hydrocarbon oil may preferably be 50 to 500, more preferably 100 to 300.

[0042] The above-mentioned low molecular weight nonpolar solvents may be used alone or in combination of two or more. For example, a combination of multiple silicone oils may be used, a combination of multiple hydrocarbon oils may be used, or a combination of silicone oil and hydrocarbon oil may be used. Furthermore, a low molecular weight nonpolar solvent may be combined with a solvent that is not a low molecular weight nonpolar solvent, and a polar solvent, such as a polar oil, may be mixed and used. The polar oil to be combined with the low molecular weight nonpolar solvent may be, for example, a polar silicone oil, a polar hydrocarbon oil, an ester oil, etc. The ester oil may be, for example, a monohydric alcohol fatty acid ester or a polyhydric alcohol fatty acid ester, specifically, ethyl ethylhexanoate, pentaerythrityl tetraethylhexanoate, etc.

[0043] In addition, it is preferable that the oily solvent has the same or similar structure as the backbone polymer of the photoresponsive compound, since this increases the solubility of the photoresponsive compound in the oily solvent. For example, if the backbone polymer of the photoresponsive compound is polydimethylsiloxane (PDMS), it is preferable to use polydimethylsiloxane (PDMS) or a silicone oil having polydimethylsiloxane (PDMS) as the main backbone as the oily solvent.

[0044] When the cosmetic composition of this embodiment is an oil-based composition, the content of the oily solvent in the composition may be preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 95% by mass or less, relative to the total amount of the composition. Furthermore, the oil-based composition may be completely free of, or substantially free of, aqueous components. Note that the phrase "substantially free of" a specific component means that the specific component may be derived from raw materials or may be unavoidably mixed in during production. Specifically, the content of the specific component relative to the total amount of the composition is 2% by mass or less, preferably 1% by mass or less, and more preferably 0.5% by mass or less.

[0045] The content of the low molecular weight nonpolar solvent in the oily solvent may be preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more. It is also preferable that the oily solvent consists of a low molecular weight nonpolar solvent or essentially consists of a low molecular weight nonpolar solvent. The expression "essentially consisting of" a predetermined component means that the predetermined component is contained in an amount of 98% by mass or more, preferably 99% by mass or more, and more preferably 99.5% by mass or more.

[0046] Furthermore, the content of silicone oil in the oily solvent may be preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more. Furthermore, it is preferable that the oily solvent consists of silicone oil or consists essentially of silicone oil.

[0047] <Cosmetic Composition> As described above, the cosmetic composition according to this embodiment has photoresponsiveness due to the presence of a photoresponsive compound. Furthermore, the cosmetic composition according to this embodiment exhibits photoresponsiveness substantially similar to that exhibited by the photoresponsive compound contained in the cosmetic composition alone. The entire cosmetic composition changes to a high-fluidity state when irradiated with light, preferably in the ultraviolet region, for example, light having a wavelength of 300 nm to 400 nm, more preferably 350 nm to 380 nm, even more preferably 360 nm to 370 nm, and even more preferably 365 nm, and changes to a low-fluidity state when light irradiation is stopped. Here, the low-fluidity state may preferably be a solid or gel-like state, and the high-fluidity state may preferably be a liquid or sol-like state. Even if both the low-fluidity state and the high-fluidity state are liquid or sol-like states, the fluidity state can be changed depending on whether or not light irradiation is performed.

[0048] When the cosmetic composition is stimulated by light irradiation and then by stopping the light irradiation, the storage modulus G' can change preferably in the range of 1 Pa or more and 1,000 Pa or less, more preferably 10 Pa or more and 500 Pa or less. Furthermore, when the storage modulus G' of the cosmetic composition is compared between a high fluidity state and a low fluidity state, the storage modulus G' in the low fluidity state (G Ｌ ') high fluid state storage modulus G' (G Ｈ The ratio value (G Ｌ ' / G Ｈ The storage modulus G') can be about 2 or more and 100 or less. The change range of the storage modulus G' between the low fluidity state and the high fluidity state can be larger than the change range of the storage modulus G' between the low fluidity state and the high fluidity state of the photoresponsive compound contained in the cosmetic composition alone. For example, the value of the ratio (G Ｌ ' / G Ｈ ') is the storage modulus G' (G ０Ｌ ') high fluid state storage modulus G' (G ０Ｈ The ratio value (G ０Ｌ ' / G ０Ｈ ') can be larger.

[0049] When the cosmetic composition is subjected to stimulation of light irradiation and cessation of light irradiation, the loss modulus G" can change preferably in the range of 0.01 Pa or more and 100 Pa or less, more preferably 1 Pa or more and 50 Pa or less. Furthermore, when the loss modulus G" of the cosmetic composition is compared between a high fluidity state and a low fluidity state, the loss modulus G" in the low fluidity state (G Ｌ Loss modulus G" (G Ｈ The ratio (G Ｌ " / G Ｈ The loss modulus G" can be about 2 or more and 1,000 or less. The change in the loss modulus G" between the low fluidity state and the high fluidity state can be larger than the change in the loss modulus G" between the low fluidity state and the high fluidity state of the photoresponsive compound alone contained in the cosmetic composition. For example, the value of the ratio (G Ｌ " / G Ｈ ") is the loss modulus G" (G ０Ｌ Loss modulus G" (G ０Ｈ The ratio (G ０Ｌ " / G ０Ｈ By measuring the change in storage modulus G' and / or the change in loss modulus G", the photoresponsiveness of a cosmetic composition that is solid or gel-like in the absence of light irradiation can be adequately evaluated.

[0050] When the cosmetic composition is stimulated by light irradiation and cessation of light irradiation, the steady flow viscosity η (mPa·s) can vary, depending on the formulation according to the purpose or use of the cosmetic composition, preferably within a range of 5 mPa·s or more and 10,000 mPa·s or less, more preferably 10 mPa·s or more and 1,000 mPa·s or less. Furthermore, depending on the formulation, the steady flow viscosity η (mPa·s) can vary, preferably within a range of 100 mPa·s or more and 15,000 Pa·s or less, more preferably 1,000 mPa·s or more and 10,000 Pa·s or less. Furthermore, when the steady flow viscosity η of a cosmetic composition is compared between a high fluidity state and a low fluidity state, the steady flow viscosity η (η Ｌ ) to the steady flow viscosity η (η Ｈ ) ratio value (η H / η L) can be preferably 1.01 or more and 100 or less, more preferably 1.1 or more and 100 or less. Depending on the formulation, it may also be preferably 1.01 or more and 50 or less, more preferably 1.1 or more and 10 or less. By measuring such a change in steady flow viscosity η, it is possible to adequately evaluate the photoresponsiveness of a liquid or sol cosmetic composition, particularly in the absence of light irradiation.

[0051] The change in fluidity due to light irradiation, which is one of the photoresponsive properties of the cosmetic composition according to this embodiment, is also reflected in the tactile sensation (feel) when the cosmetic composition is touched or applied, and in the appearance, such as gloss. For example, when the cosmetic composition is irradiated with light to change it from a low-fluidity state to a high-fluidity state, the smoothness of the cosmetic composition when applied can be improved. Furthermore, when the cosmetic composition is irradiated with light to change it from a low-fluidity state to a high-fluidity state, the surface of the cosmetic composition can become smoother and more glossy.

[0052] In this embodiment, the addition of the above-described photoresponsive compound allows a cosmetic composition with high viscosity (static viscosity and / or dynamic viscosity) to be obtained. That is, the photoresponsive compound in this embodiment contributes to the development of the photoresponsiveness of the cosmetic composition and also provides a moderate thickening of the composition. Therefore, when preparing a cosmetic composition with high viscosity, the amount of a thickener conventionally used can be reduced, or the addition of a separate thickener can be omitted. Furthermore, when the cosmetic composition is an emulsion-based composition, a good emulsified state can be easily achieved without the addition of a separate thickener or even with a small amount of a thickener, and the emulsified state can be stably maintained for a long period of time.

[0053] The light irradiation of the cosmetic composition according to this embodiment can be carried out under conditions of 0 to 100°C, and is preferably carried out at room temperature (5 to 35°C). The intensity of the light to be irradiated is 0.2 mW / cm. ２ More than 40mW / cm ２ This range of light intensity also includes the intensity of ultraviolet light from the sun outdoors.

[0054] <Other Components> The cosmetic composition according to this embodiment, or cosmetics, etc. prepared using the cosmetic composition, may contain other components such as surface-treated or untreated inorganic powders (including UV scattering agents), resin particles, solid oily components, preservatives, thickeners, moisturizers, surfactants, etc., depending on the type and function of the cosmetic, etc. When the cosmetic composition is an oil-in-water or water-in-oil emulsion composition, it also contains an aqueous component. These other components may be contained in amounts depending on the type and function of the cosmetic composition, as long as they do not inhibit the photoresponsiveness of the cosmetic composition.

[0055] When the cosmetic composition according to this embodiment is an emulsion-based composition, the surfactant contained in the cosmetic composition is not particularly limited as long as it is one used in the field of cosmetics, etc., but a nonionic surfactant is preferred. Furthermore, when the backbone polymer of the photoresponsive compound is polydimethylsiloxane (PDMS, dimethicone) or a derivative thereof, and / or the oil-based solvent is polydimethylsiloxane (PDMS, dimethicone) or a derivative thereof, a silicone-based surfactant is preferred because it exhibits a high emulsifying effect. The silicone-based surfactant may be a polyether-modified silicone, more specifically, a silicone having a polyether chain, a silicone having a polyether chain and a silicone chain, or the like. One or two types of surfactants may be used in combination.

[0056] <Specific Applications, etc.> As described above, the fluidity of a cosmetic composition can be changed by light irradiation, for example, between a solid and a liquid, or between a gel and a sol. Therefore, for example, when the cosmetic composition is used as a sunscreen, even if a portion of the sunscreen applied evenly to the skin is removed by scratching or the like, the cosmetic composition can be made highly fluid by going outdoors or irradiating the cosmetic composition with UV rays using an UV irradiation device, and a uniform layer of sunscreen can be automatically reformed without the user's touch. Furthermore, when this embodiment is a makeup cosmetic such as lip gloss, for example, the surface gloss can change between outdoor exposure to UV rays and indoor exposure to no UV rays. This allows the makeup nuance (matte / gloss) to be automatically changed indoors and outdoors, even with the same makeup cosmetic. Furthermore, the texture of skincare products such as creams can be changed indoors and outdoors, for example, providing a watery, refreshing feel when applied outdoors under UV rays and a thick, firm feel indoors under no UV rays.

[0057] Furthermore, as described above, the cosmetic composition according to this embodiment can change color when exposed to ultraviolet light. Therefore, when the cosmetic composition is used as a sunscreen, body cream, or the like, it is possible to determine whether or not ultraviolet light is being irradiated and the intensity of the ultraviolet light from the color of the composition. In other words, the cosmetic composition can function as a UV sensor.

[0058] The following describes the embodiments in more detail based on experimental examples, but the embodiments of the present invention are not limited to these experimental examples.

[0059] <Synthesis of Photoresponsive Compound (Crosslinking Compound)> The photoresponsive compound used in the experiment was synthesized as follows.

[0060] To a mixture of trifunctional silanol (100 mg), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) (69.6 mg), and tetrahydrofuran (THF) (9 mL), a THF solution (12 mL) of hexamethylcyclotrisiloxane (D3) (10 g) was added and stirred at 25°C. After 2 hours, pyridine (4.84 mL) and chlorodimethylsilane (2.18 mL) were added in this order, and the mixture was stirred for an additional 12 hours. The reaction mixture was poured into excess water / hexane, and the aqueous phase was separated and extracted with hexane. The hexane phase was washed with water and then added with sodium sulfate (Na ２ SO ４ The resulting oily product was washed with acetone and concentrated to dryness with chloroform (CHCl ３ The resulting solution was concentrated and dried under reduced pressure to give 7.2 g of a colorless oily vinyl-terminated three-arm star polydimethylsiloxane (H-terminated three-arm star PDMS).

[0061] Furthermore, a mixture of the vinyl-terminated three-arm star PDMS (5.0 g), 2-(4-vinyl)phenyl)-4,5-diphenyl-1H-imidazole (1.10 g), Karstedt's catalyst (15 μL), and THF (10 mL) was refluxed for 16 hours. After cooling to room temperature, the mixture was washed with methanol and acetone and dried under reduced pressure. This yielded 2.62 g of a crosslinked three-arm star PDMS compound with lophine end groups (PDMS-lophine) as a photoresponsive compound in the form of a white solid.

[0062] The crosslinkable polymer constituting the crosslinked compound, i.e., three-branched star PDMS with lophine end groups, had a number-average molecular weight Mn of 45,345, a weight-average molecular weight Mw of 78,789, and a molecular weight distribution D (Mw / Mn) of approximately 1.74.

[0063] Furthermore, a mixture of potassium hydroxide (0.96 g), potassium ferricyanide (5.67 g), and water (200 ml) was added to a mixture of the above-mentioned lophine-terminated three-arm PDMS (PDMS-lophine) (2.50 g) and hexane (200 mL), and the mixture was stirred in the dark at 25° C. for 2 hours. The hexane phase of the reaction mixture was separated and washed with water, and then sodium sulfate (Na ２ SO４ The resulting solution was concentrated and dried under reduced pressure to obtain 1.92 g of a crosslinked compound (PDMS-HABI) in which the ends of polydimethylsiloxane having lophine end groups were crosslinked to each other.

[0064] Compositions were prepared using the synthesized photoresponsive compounds in various formulations and evaluated as follows: [1] Experimental Example 1 <Composition Preparation I> (Examples 1-1 to 1-7) The crosslinked compounds (crosslinked compounds of three-branched star-shaped PDMS having lophine terminal groups; PDMS-HABI) were each added to the oil-based solvents shown in Table 1 and stirred to attempt the preparation of compositions with a PDMS-HABI concentration of 5% by mass. When simple dissolution was difficult, stirring and dissolution were attempted while irradiating with a UV lamp (peak wavelength 356 nm).

[0065] In Table 1, *1: Evaluated by viscoelasticity measurement

[0066] In Examples 1-1 to 1-3, the solvents shown in Table 1 were used alone, but in Examples 1-4 to 1-7, two solvents shown in Table 1 were used in a mass ratio of 1:1.

[0067] (Examples 1-8 to 1-12) Furthermore, for compositions using dimethicone (6cs) alone as the oily solvent, compositions were prepared by changing the concentration of PDMS-HABI as shown in Table 2.

[0068] In Table 2, *2: Evaluated by steady flow viscosity measurement *3: Evaluated by viscoelasticity measurement

[0069] <Evaluation> The compositions of each example were evaluated as follows: (Solubility evaluation) It was visually confirmed whether the photoresponsive compound was well dissolved in the solvent. The evaluation criteria were as follows: ◯: No remaining solid PDMS-HABI was found in the composition. Δ: Remaining solid PDMS-HABI was found in the composition, but only in small amounts. ×: A large amount of remaining solid PDMS-HABI was found in the composition.

[0070] The photoresponsiveness of the compositions was further evaluated. Specifically, the photoresponsiveness was evaluated by physical property measurement and by visual observation. Regarding the photoresponsiveness evaluation by physical property measurement, in order to perform a more appropriate evaluation when the prepared compositions were in a solid or gel state and when they were in a liquid or sol state in the non-irradiated state, at least viscoelasticity measurement was performed for the former and steady flow viscosity measurement for the latter, although in some cases both measurements were performed. The term "liquid or sol state" refers to a state in which the composition flows immediately after being placed on a glass slide without UV irradiation in the photoresponsiveness evaluation by visual observation (a glass slide tilt test, described in detail below).

[0071] (Photoresponsiveness evaluation by physical property measurement) = Viscoelasticity measurement (solid or gel composition) = In order to evaluate the photoresponsiveness of the solid or gel cosmetic composition, the composition of each example was intermittently irradiated with light, and the storage modulus G' (Pa) and loss modulus G" (Pa) were measured over time. The irradiated light was 365 nm (36 mW / cm ２ ) ultraviolet light, and a rotational rheometer (MCR302, manufactured by Anton Paar) was used for the measurements. Specifically, a sample was applied to the surface of a glass lower plate to a thickness of 0.10 mm, and a parallel plate (diameter 12 mm) was placed on top of it and rotated at a frequency of 1 Hz. Irradiation began 120 seconds after the start of measurement and continued for 120 seconds, after which irradiation was stopped for 300 seconds. This cycle of irradiation and irradiation stop was repeated two or more times. Figures 1 to 3 show the changes over time in the storage modulus G' (Pa) and loss modulus G" (Pa) of Examples 1-1 to 1-3, respectively.

[0072] The storage modulus G' (G Ｌ The storage modulus G' (G Ｈ The ratio value (G Ｌ ' / G Ｈ '), or the loss modulus of elasticity in the low flow state G" (G Ｌ Loss modulus G" (G Ｈ The ratio (G Ｌ " / G Ｈ The photoresponse was evaluated as follows: ◯: G Ｌ' / G Ｈ 'Or G Ｌ " / G Ｈ The value of " was 2 or more, and a significant reversible change in fluidity was observed. Ｌ ' / G Ｈ 'Or G Ｌ " / G Ｈ The value of " was 1.1 or more and less than 2, and some reversible change in fluidity due to light irradiation was observed. ×: G Ｌ ' / G Ｈ 'Or G Ｌ " / G Ｈ When the value of " was less than 1.1, no flow upon irradiation with light was observed, or no reversible change in flowability was observed.

[0073] = Steady flow viscosity measurement (liquid or sol composition) = In order to evaluate the photoresponsiveness of the liquid or sol cosmetic composition, the composition of each example was irradiated with light and the steady flow viscosity η (mPa s) was measured over time. The irradiated light was 365 nm (36 mW / cm ２ ) ultraviolet light, and a rotational rheometer (MCR302, manufactured by Anton Paar) was used for the measurements. Specifically, a sample was applied to the surface of a glass lower plate to a thickness of 0.10 mm, and a parallel plate (12 mm diameter) was placed on top of it, and the measurements were performed under strain rates of 10 to 100 / sec. Steady flow viscosity measurements were performed before irradiation, 120 seconds after irradiation, and 15 minutes after irradiation had stopped. Figures 4 to 6 show the change over time in steady flow viscosity η (mPa s) for Examples 1-8 to 1-10, respectively. In Figures 4 to 6, the horizontal axis represents shear rate (1 / s) and the vertical axis represents viscosity (mPa s), and the viscosity change for dimethicone alone is also shown for comparison.

[0074] In addition, the steady flow viscosity η (η Ｌ ) after 120 seconds of irradiation, the steady flow viscosity η (η Ｈ ) to the ratio value (η Ｌ / η Ｈ ) was used to evaluate the photoresponsiveness as follows: ◯: η Ｌ / η Ｈ When the value of η was 2 or more, a significant reversible change in fluidity was observed. Ｌ / η ＨThe value of η was 1.1 or more and less than 2, and some reversible change in fluidity due to light irradiation was observed. ×: η Ｌ / η Ｈ When the value of ρ was less than 1.1, no flow upon irradiation with light was observed, or no reversible change in flowability was observed.

[0075] Incidentally, for Example 1-10, evaluation was carried out by both photoresponsiveness evaluation by viscoelasticity measurement and steady flow viscosity measurement.

[0076] (Evaluation of photoresponse by visual observation (slide glass tilt test)) 0.5 g of the obtained solid or gel composition was applied to a slide glass, and the slide glass was tilted by about 30° relative to the horizontal direction, and ultraviolet light (365 nm) (15 mW / cm ２ ) was irradiated for a maximum of approximately 60 seconds, and the state was observed visually. If the state changed and the composition became fluid, the irradiation was stopped and the state was observed (to confirm whether it had returned to the state at the time of application). Note that if the prepared composition was in a liquid state, i.e., if it flowed on the slide glass without being irradiated with ultraviolet light, the visual evaluation of the photoresponsiveness was not performed. The evaluation criteria were as follows: ◯: A significant reversible change in fluidity due to light irradiation was observed. Δ: A slight reversible change in fluidity due to light irradiation was observed. ×: No fluidity was observed at all due to light irradiation, or no reversible change in fluidity was observed.

[0077] The solubility during preparation of each example and the evaluation results of the prepared compositions are shown in Tables 1 and 2.

[0078] Experimental Example 1 demonstrated that a composition containing a photoresponsive compound (a crosslinked compound (PDMS-HABI) formed by crosslinking the ends of polydimethylsiloxane having lophine end groups) and an oily solvent can reversibly change its fluidity upon irradiation with light. Furthermore, it was found that both the solubility and photoresponsiveness were excellent, particularly when the concentration of the photoresponsive compound was 3% by mass or more and 5% by mass or less.

[0079] [2] Experimental Example 2 <Preparation of Composition> (Examples 2-1 and 2-2) The components shown in Table 3 were mixed in a conventional manner to prepare compositions (lip glosses).

[0080] In Table 3, *4: Evaluation based on Example 2-2

[0081] <Evaluation> (Photoresponsiveness by visual observation (tilt glass slide test)) For each example, evaluation of photoresponsiveness by a tilt glass slide test was carried out in the same manner as in "[1] Experimental Example 1." The results are shown in Table 3.

[0082] (Smoothness under light irradiation) The smoothness (feel in use) was evaluated when the cosmetic of each example was applied to the lips with a tip under light irradiation. The evaluation criteria were as follows, with Example 2-2 under light irradiation as the standard. ◎: Significantly superior in smoothness to Example 2-2. ○: Slightly superior in smoothness to Example 2-2. △: Equivalent to the smoothness of Example 2-2. ×: Inferior in smoothness to Example 2-2.

[0083] Experimental Example 2 demonstrated that the fluidity of a cosmetic product (Example 2-1) prepared using a photoresponsive compound can be reversibly changed by light irradiation. It was also found that the smoothness of the cosmetic product is improved by light irradiation. Therefore, it was found that the cosmetic product according to this embodiment can be used in applications where it is desired to change the feel of use indoors or outdoors.

[0084] In both the slide glass tilt test and the evaluation of smoothness, when ultraviolet light irradiation and its cessation were alternately repeated the first time, changes almost identical to those observed the first time were observed with ultraviolet light irradiation from the second time onwards.

[0085] [3] Experimental Example 3 <Preparation of Cosmetic> (Example 3-1) The photoresponsive compound (PDMS-HABI) synthesized in Experimental Example 1 was dissolved in dimethicone (6cs) until homogeneous while irradiating with ultraviolet light (wavelength 365 nm) for 1 hour. PEG-10 dimethicone and PEG-9 polydimethylsiloxyethyl dimethicone were then added, and the solution was dissolved until homogeneous while irradiating with ultraviolet light in the same manner as above. Water was then gradually added while irradiating with ultraviolet light in the same manner as above, to obtain an emulsion composition. The blending amounts of each component raw material used were as shown in Table 4.

[0086] (Examples 3-2 and 3-3) Emulsion compositions were obtained by blending the raw ingredients in the same manner as in Example 3-1, but the blending amounts were different as shown in Table 4.

[0087] (Example 3-4) An emulsion composition was obtained from the raw ingredients shown in Table 4 without using the photoresponsive compound (PDMS-HABI).

[0088] <Evaluation> (Viscosity Change Due to UV Irradiation) The steady flow viscosity (mPa s) of each composition obtained was measured at room temperature using a rotational viscometer (B-type viscometer, manufactured by Anton Paar, Visco QC100) at 12 rpm for 1 minute. ２ ) and left for 5 minutes, and then the steady flow viscosity was measured in the same manner. Table 4 shows the steady flow viscosities before and after ultraviolet irradiation. If there was a difference in the kinematic viscosity before and after ultraviolet irradiation, it was evaluated that there was a change in the flow state due to light irradiation.

[0089] (Color Change) The obtained emulsion composition was irradiated with ultraviolet light (wavelength 365 nm, 36 mW / cm ２ The presence or absence of a color change was visually confirmed and evaluated as "yes" or "no."

[0090] In Table 4, *5: Silicone KF-6017P (manufactured by Shin-Etsu Chemical Co., Ltd.) *6: Silicone SC0938B (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0091] In addition, in both the evaluation based on viscosity change and the evaluation based on color change, when ultraviolet light irradiation and its cessation were alternately repeated the first time, changes almost similar to those observed the first time were observed with ultraviolet light irradiation from the second time onwards.

[0092] Experimental Example 3 demonstrated that the fluidity of emulsion compositions (Examples 3-1 to 3-3) prepared using a photoresponsive compound can be reversibly changed by light irradiation. Furthermore, a comparison of the viscosities of Examples 3-1 to 3-3 and Example 3-4 before UV irradiation revealed that the photoresponsive compound has the effect of increasing viscosity. Furthermore, it was also found that the color of the composition changed upon light irradiation. The color of the composition was milky white before UV irradiation, but was an opaque light purple after UV irradiation.

[0093] Although the present invention has been described above based on specific embodiments and examples, these embodiments and examples are presented only as examples, and the present invention is not limited to the above embodiments and examples. Various changes, modifications, substitutions, deletions, additions, combinations, etc. are possible within the scope of the disclosure of the present invention.

[0094] This application claims priority based on Japanese Patent Application No. 2023-124853 filed on July 31, 2023, and Japanese Patent Application No. 2023-191673 filed on November 9, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A cosmetic composition comprising a crosslinking compound in which a crosslinkable polymer having a substituted or unsubstituted lophine group at at least one end of a backbone polymer is crosslinked by bonds between the lophine groups, and in which the fluidity of the cosmetic composition is reversibly changed by irradiation with light of a specified wavelength.

2. The cosmetic composition according to claim 1, which is an oil-based composition further containing an oily solvent.

3. The cosmetic composition according to claim 1, which is an emulsion composition containing an oil-based solvent and an aqueous solvent.

4. The cosmetic composition according to claim 2 or 3, wherein the oil-based solvent comprises a low molecular weight non-polar solvent.

5. The cosmetic composition according to claim 4, wherein the low molecular weight non-polar solvent is one or more of a silicone oil and a hydrocarbon oil.

6. The cosmetic composition according to claim 2 or 3, wherein the content of the crosslinking compound is 0.1% by mass or more and 50% by mass or less based on the total amount of the crosslinking compound and the oily solvent.

7. A cosmetic composition according to any one of claims 1 to 3, wherein the content of the crosslinking compound is from 0.01% by mass to 50% by mass, based on the total amount of the cosmetic composition.

8. The cosmetic composition according to any one of claims 1 to 3, wherein the backbone polymer is a polysiloxane.

9. The cosmetic composition according to any one of claims 1 to 3, wherein the backbone polymer has a central core, and the number of branched chains extending from the central core is 3 or more and 6 or less.

10. The crosslinkable polymer is represented by the formula (3): The cosmetic composition according to claim 1 , wherein n is an integer of 2 or more and 1,000 or less, and all of the branched chains have the same structure.

11. The cosmetic composition according to any one of claims 1 to 3, wherein the light of the specified wavelength is ultraviolet light.

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