Biodegradable silicone elastomer particles having hydrophilic group in crosslinked part, and cosmetic composition and other uses

Abstract

[Problem] To provide: novel silicone elastomer particles which have excellent biodegradability and are capable of imparting excellent texture and feeling of use to a cosmetic; and uses of the silicone elastomer particles. [Solution] Provided are: biodegradable silicone elastomer particles each having a structure in which at least two silicon atoms in the silicone elastomer particle are crosslinked by a divalent organic group that contains a hydrophilic group, and having a polyorganosiloxane structure represented by –(R2SiO)m– (wherein R is an alkyl group having 1 to 20 carbon atoms, which is unsubstituted or substituted by a halogen atom, an aryl group having 6 to 22 carbon atoms, or a hydroxy group, and m is a number within the range of 1-1,000) in the silicone elastomer particle; and uses of the silicone elastomer particles.

Description

Biodegradable silicone elastomer particles having hydrophilic groups at crosslinked portions and cosmetic compositions and other uses

[0001] The present invention relates to novel silicone elastomer particles that have a structure in which silicon atoms are crosslinked by divalent organic groups containing hydrophilic groups, are highly biodegradable, and can impart an excellent feel and sensation to cosmetics. Because these biodegradable silicone elastomer particles have a crosslinked structure containing hydrophilic groups that are active toward biodegradation, the primary particles are expected to disintegrate in nature through decomposition reactions by microorganisms, etc., generating non-crosslinked siloxane molecules, and the particles are expected to behave as biodegradable particles. Furthermore, the present invention relates to cosmetic ingredients, cosmetic compositions, organic resin additives, and other uses that contain these biodegradable silicone elastomer particles.

[0002] Silicone elastomer particles are obtained by curing addition-reaction-curable silicone compositions or condensation-reaction-curable silicone compositions, and although their particle size and oil absorption properties vary depending on the production method, they are widely used as cosmetic ingredients, stress relief agents for thermoplastic resins, etc. For example, the present applicant has proposed silicone particles with excellent dispersibility, high lipophilicity, and excellent storage stability, such as silicone particles containing alkylene groups having 4 to 20 carbon atoms, which are obtained by curing a crosslinkable composition for forming silicone particles described in Patent Document 1, which has a low content of silicon-bonded hydrogen atoms per unit mass and contains an alkenyl group having 4 to 20 carbon atoms, such as a hexenyl group.

[0003] On the other hand, the present applicants have focused on an essential problem with conventional silicone elastomer particles. Conventional silicone elastomer particles are formed through a crosslinking reaction of organopolysiloxane raw materials, such as a hydrosilylation reaction. However, this crosslinked structure is chemically stable, and if these silicone elastomer particles were released into the natural environment, there is a possibility that, like so-called microplastics, they would persist in nature without decomposing, at least for a short period of time. Therefore, in order to reduce the risk to the global environment, there is likely to be a latent demand in the market for silicone elastomer particles that have sufficient performance to smoothly replace or replace existing silicone elastomer particles and are expected to be highly biodegradable. In light of this potential market demand, the present applicants have proposed copolymer particles in Patent Documents 2 to 7. Furthermore, Patent Documents 8 and 9 propose silicone-based particles that are expected to be biodegradable.

[0004] On the other hand, Patent Documents 10 and 11 propose forming silicone elastomer particles through a crosslinking reaction between a polyoxyalkylene-containing compound and an organopolysiloxane raw material by a hydrosilylation reaction or the like, but such polyoxyalkylene-crosslinked silicone elastomer particles are prone to swelling or deformation as a whole, making it difficult to impart sufficient rubber properties, and it is difficult for individual elastomer particles to have the same hardness and elasticity (rubber properties) as conventional products, and the resulting feeling and texture when used.Furthermore, since they do not have crosslinking sites active in biodegradation, even if they have hydrophilic sites in the molecule, they do not provide silicone elastomer particles that can be expected to be highly biodegradable, and they do not provide those skilled in the art with any structural suggestions regarding biodegradability.

[0005] On the other hand, Non-Patent Documents 1 to 3 disclose the biodegradability of polycarbonate compounds having a polyol terminal structure. Non-Patent Document 1 indicates that polycarbonates having aromatic groups such as phenyl groups are difficult to biodegrade, while polycarbonates composed of aliphatic groups consisting of straight-chain hydrocarbons are readily biodegradable. Non-Patent Documents 2 and 3 also indicate the biodegradability of polycarbonates composed of aliphatic groups. There is no mention or suggestion of radically polymerizable polycarbonate-modified silicone compounds that have multiple polycarbonate structures with a relatively low degree of polymerization within the molecule and also have a polysiloxane structure of a specific structure, nor of silicone-polycarbonate copolymer particles obtained from such compounds via radical polymerization. In particular, there is no specific description or suggestion of biodegradable silicone elastomer particles in which crosslinked structures between silicon atoms are formed by a crosslinking agent having a specific hydrophilic group.

[0006] Furthermore, Non-Patent Document 4 discloses polydimethylsiloxane (PDMS) particles having a polycaprolactone (PCL) structure, and discloses that the particles are rubber-like elastomer particles that are biodegradable and have an elastic modulus. However, it does not provide any specific description or suggestion regarding biodegradable silicone elastomer particles in which a crosslinked structure between silicon atoms is formed by a crosslinking agent having a specific hydrophilic group.

[0007] International Patent Publication WO2017 / 191798 International Patent Publication WO2022 / 138346 International Patent Publication WO2023 / 120689 International Patent Publication WO2023 / 120690 International Patent Application PCT / JP2023 / 46100 International Patent Application PCT / JP2023 / 46101 International Patent Application PCT / JP2023 / 46102 International Patent Publication WO2022 / 019179 International Patent Publication WO2023 / 238840 Japanese Patent Publication No. 2001-163732 People's Republic of China Patent Publication No. 111393679

[0008] Biodegradation of Aliphatic and Aromatic Polycarbonates (Trishul Artham, Mukesh Doble et al., Macro-Molecular Bioscience, 2007)Phylogenetic Affiliation of Soil Bacteria That Degrade Aliphatic Polyesters Available Commercially as Biodegradable Plastics (Tetsushi Suyama et al., Applied and Environmental Microbiology, 1998)Bacterial isolates degrading aliphatic polycarbonates (Tetsushi Suyama et al., FEMS Microbiology Letters, 1998) PCL-PDMS-PCL Copolymer-Based Microspheres Mediate Cardiovascular Differentiation from Embryonic Stem Cells (Liqing Song et al., TISSUE ENGINEERING: Part C Volume 23, Number 10, 2017)

[0009] 1 shows the results of an enzymatic decomposition test (test time - decomposition rate %) of silicone elastomer particles of Examples and Comparative Examples.

[0010] The present invention has been made to solve the above-mentioned problems, and provides biodegradable silicone elastomer particles that, when incorporated into cosmetic compositions and the like, can achieve a feel and sensation of use that is equal to or better than that of conventional silicone elastomer particles, and that have a structure that is active toward biodegradation.

[0011] Another object of the present invention is to provide, by using the copolymer particles, cosmetic raw materials, organic resin additives, and other applications that are excellent in terms of feel when used, etc. Another object of the present invention is to provide a cosmetic composition that contains the copolymer particles and is excellent in terms of feel when used, etc.

[0012] Furthermore, the present invention aims to provide copolymer particles, raw materials for synthesizing the same, and uses thereof, which have performance equal to or greater than that of conventional silicone elastomer particles and are expected to be biodegradable, thereby reducing the potential risk to the global environment, allowing for industrially sustainable and stable use, and which can be promoted as a biodegradable, eco-friendly material to users and general consumers who are concerned about the impact on the global environment.

[0013] As a result of extensive research aimed at solving the above problems, the present inventors have discovered a silicone elastomer having a structure in which at least two silicon atoms in the silicone elastomer particles are crosslinked by a divalent organic group containing a hydrophilic group, and wherein the silicone elastomer particles contain -(R ２ SiO) ｍ The present inventors have discovered that the above problems can be solved by biodegradable silicone elastomer particles having a polyorganosiloxane structure represented by the formula: (wherein R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group, and m is a number in the range of 1 to 1,000), and have arrived at the present invention.

[0014] Similarly, the present inventors discovered that the above problems can be solved by using a cosmetic ingredient, organic resin additive, cosmetic, or organic resin containing the biodegradable silicone elastomer particles, and arrived at the present invention.

[0015] When blended into cosmetic compositions, etc., the biodegradable silicone elastomer particles of the present invention can achieve a feel and sensation of use that is equal to or better than that of conventional silicone elastomer particles. Furthermore, by using the biodegradable silicone elastomer particles of the present invention, it is possible to provide cosmetic ingredients, organic resin additives, and other uses that contain the biodegradable silicone elastomer particles. Furthermore, cosmetic compositions containing the biodegradable silicone elastomer particles of the present invention can provide cosmetics that are excellent in feel and sensation of use.

[0016] The biodegradable silicone elastomer particles of the present invention have a structure in which polyorganosiloxane chains and divalent organic groups containing hydrophilic groups are crosslinked within the elastomer particles, and the divalent organic groups containing hydrophilic groups are active in biodegradation reactions, and are designed so that in a biodegradable environment, the crosslinked structure formed between silicon atoms in the copolymer particles at least partially cleaves, and the primary particles are disintegrated, generating non-crosslinked polyorganosiloxanes.Therefore, the elastomer particles of the present invention are biodegradable and can reduce risks to the global environment, and can be promoted as an eco-friendly material that can be used with a considerable sense of security by users and general consumers who are concerned about the impact on the global environment.

[0017] In this specification, the term "(meth)acrylic" means "acrylic or methacrylic," and when expressed as "(meth)acrylic-modified," it means that the modifying group may be either or both of an acrylic-modified group and a methacrylic-modified group. Similarly, the term "(meth)acryloxy" means "methacryloxy or acryloxy," and the term "(meth)acryloxy group-containing organic group" means that it may be either or both of a methacryloxy group-containing organic group and an acryloxy group-containing organic group.

[0018] [Silicone Elastomer Particles] The biodegradable silicone elastomer particles of the present invention, their uses including as a cosmetic raw material, their production method, and cosmetic compositions and organic resins (including paints and coating agents) containing them will be described in detail below.

[0019] [(A) Crosslinking Agent Having Hydrophilic Group in Molecule] The silicone elastomer particles of the present invention are characterized by having a structure crosslinked by a divalent organic group containing a hydrophilic group. Here, the divalent organic group containing a hydrophilic group is active in biodegradation reactions, and imparts to the silicone elastomer particles the property that the crosslinked structure formed between silicon atoms in the copolymer particles is at least partially cleaved in a biodegradable environment, and the silicone elastomer particles are characterized by the following: (A) (A1) both ends of the molecular chain are RＡｌｋ R ２ SiO (wherein, R Ａｌｋ (A1) a crosslinking agent having at least two radically polymerizable functional groups in its molecule and containing a hydrophilic group, and (A2) a crosslinking agent having at least two radically polymerizable functional groups in its molecule and containing a hydrophilic group in its molecule, and wherein R is a carbon-carbon double bond-containing organic group, and R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group. Note that when organohydrogenpolysiloxanes or the like are crosslinked with polyether compounds or the like that simply have unsaturated bonds at their terminals, not only is sufficient biodegradability not possible, but silicone elastomer particles having rubber physical properties may not be obtained.

[0020] The crosslinked structure is preferably formed by a crosslinking reaction selected from a radical polymerization reaction and a hydrosilylation reaction, and preferably has a structure in which at least two silicon atoms in the silicone elastomer particles are crosslinked by one or more reactions selected from a radical polymerization reaction involving the above-mentioned component (A) and a hydrosilylation reaction of silicon-bonded hydrogen atoms. Note that component (A) may be reactive to both a radical polymerization reaction and a hydrosilylation reaction of silicon-bonded hydrogen atoms, and in such cases, it may be introduced into the silicone elastomer particles by either reaction or both reactions, without any particular limitation.

[0021] The crosslinking agent (A) may be hydrosilylation reactive, and (A1) is a compound having R Ａｌｋ R ２ Preferably, the crosslinking agent is terminated with a hydrosilylation-reactive silyl group represented by SiO and contains a hydrophilic group within the molecule. Use of a hydrophilic compound having a hydrosilylation-reactive silyl group at the end may further improve the rubber properties and biodegradability of the resulting silicone elastomer particles.

[0022] In the formula, R Ａｌｋ is a carbon-carbon double bond-containing organic group, and —C(═O)—R１ -CR ２ =CH ２ and an alkenyl terminal group having 2 to 20 carbon atoms. １ is a chemical bond between CH and C(=O) or a divalent organic group having 0 to 20 carbon atoms, and is preferably a simple chemical bond such as "-C(=O)-CH=" or an alkylene group having 1 to 20 carbon atoms represented by CmH2m such as "-C(=O)-CmH2m-CH=" (m is a number in the range of 1 to 20) (note that R １ is a chemical bond between CH and C(=O), m is 0.) Also, R ２ is a hydrogen atom or a methyl group, which provides an acrylic-modified group, a methacrylic-modified group, or an alkenyl group, respectively.

[0023] R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group, and industrially, it is preferred that each R is independently a methyl group or a phenyl group.

[0024] The crosslinking agent of component (A1) is a crosslinking agent containing a hydrophilic group in the molecule, and it is particularly preferable that the hydrophilic group has a polyether structure, in particular a polyoxyethylene-polyoxypropylene block copolymer structure (hereinafter sometimes referred to as a "Pluronic(R) structure"). The crosslinking agent of component (A1) into which such a structure has been introduced may further have a polyester structure or a polycaprolactone structure.

[0025] Examples of such component (A1) include: An example is a modified polycaprolactone compound having a polyoxyethylene-polyoxypropylene block copolymer structure in the molecule, represented by the formula: where m and n are positive numbers, and m+n is preferably in the range of 2 to 100, preferably 2 to 10, and more preferably 2 to 8. Furthermore, a is the number of ethyleneoxy (EO) units, b is the number of propyleneoxy (PO) units, a and b are positive numbers, and a+b is preferably in the range of 2 to 100, preferably 4 to 50, and more preferably 6 to 30. In the formula, one or both of the vinyl groups at the molecular chain terminals bonded to silicon atoms may be the R Ａｌｋ The vinyl group may be replaced by a carbon-carbon double bond-containing organic group other than the vinyl group.

[0026] The crosslinking agent (A) may be radically polymerizable, and may be (A2) a crosslinking agent having at least two radically polymerizable functional groups in the molecule and containing a hydrophilic group in the molecule. Such component (A2) contains a hydroxyl (OH) group or a polyether structure that imparts hydrophilicity to the crosslinked portion, and preferably has two or more hydroxyl (OH) groups or a highly hydrophilic polyether structure. More specifically, it may be, and is preferably, one or more crosslinking agents selected from (a2-1) a sorbitan fatty acid ester or polyoxyalkylene sorbitan fatty acid ester having at least two radically polymerizable functional groups in the molecule, and (a2-2) a crosslinking agent having at least two radically polymerizable functional groups and a polyether structure in the molecule.

[0027] The radical polymerizable functional group is not particularly limited, but R Ａｌｋ Similarly, a carbon-carbon double bond-containing organic group is preferred, such as —C(═O)—R １ -CR ２ =CH ２ and an alkenyl terminal group having 2 to 20 carbon atoms (R １ and R ２ is the same group as defined above).

[0028] The sorbitan fatty acid ester or polyoxyalkylene sorbitan fatty acid ester of component (A2) preferably has at least two radically polymerizable functional groups in the molecule and is a crosslinking agent selected from sorbitan lauryl ester, sorbitan stearyl ester, sorbitan oleyl ester, and polyoxyethylene sorbitan oleyl ester. An example is a sorbitan fatty acid ester having two (meth)acrylic terminal groups in the molecule, as shown below. In the formula, R' may be an alkyl group having 8 to 22 carbon atoms (such as a lauryl group, stearyl group, or oleyl group). Such sorbitan fatty acid esters or polyoxyalkylene sorbitan fatty acid esters are hydrophilic due to the presence of multiple hydroxyl (OH) groups in the molecule, and as a crosslinking agent in the present invention, they improve the biodegradability of the resulting silicone elastomer particles.

[0029] The crosslinking agent (A2) containing at least two radically polymerizable functional groups and a polyether structure in the molecule is preferably a crosslinking agent having a polyester structure or a polycarbonate structure, and may also have a polycaprolactone structure. The polyether structure in the crosslinking agent (A2) is particularly preferably a polyoxyethylene-polyoxypropylene block copolymer structure ("Pluronic(R) structure"). When the polyether structure in component (A2) is composed of ethyleneoxy (EO) units and propyleneoxy (PO) units, it is represented by the formula (EO)a(PO)b, where a and b are both positive numbers, and a+b is preferably in the range of 2 to 100, preferably 4 to 80, and more preferably 6 to 70.

[0030] [Crosslinking Reactive Silicone Composition] The silicone elastomer particles of the present invention comprise: (A) the aforementioned crosslinking agent containing a hydrophilic group in the molecule; (B) at least one reactive organopolysiloxane selected from the following components (b1) and (b2): (b1) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in the molecule; and (b2) an organopolysiloxane having at least three (meth)acryloxy group-containing organic groups in the molecule, each of which is at least one type selected from methacryloxy group-containing organic groups and acryloxy group-containing organic groups; and (C) one or more curing agents selected from (c1) a hydrosilylation reaction catalyst and (c2) a radical polymerization initiator. and a crosslinkable silicone composition capable of being crosslinked by one or more reactions selected from a radical polymerization reaction and a hydrosilylation reaction of silicon-bonded hydrogen atoms.

[0031] [Radical Polymerization Reaction-Type Silicone Elastomer Particles] These silicone elastomer particles are obtained by radically polymerizing an organopolysiloxane having three or more silicon-bonded radically reactive functional groups, such as (meth)acryloxy group-containing organic groups, bonded to silicon atoms within the molecule with the aforementioned component (A2) in the presence of a radical polymerization initiator, and are characterized in that at least two silicon-silicon bonds within the silicone elastomer particles comprise a crosslinked structure formed by a radical polymerization reaction between the silicon-bonded radically reactive functional groups in component (A) and the silicon atom-bonded radically reactive functional groups.

[0032] [Hydrosilylation Reaction-Type Silicone Elastomer Particles] These silicone elastomer particles are obtained by subjecting an organopolysiloxane (=organohydrogenpolysiloxane) having three or more silicon-bonded hydrogen atoms in the molecule and the aforementioned component (A1) to a hydrosilylation reaction in the presence of a hydrosilylation reaction catalyst, and are characterized in that at least two silicon-silicon bonds within the silicone elastomer particles comprise a crosslinked structure formed by a hydrosilylation reaction (addition reaction) between a hydrosilylation-reactive silyl group in component (A1) and a silicon-bonded hydrogen atom.

[0033] The silicone elastomer particles of the present invention may further comprise -(R ２ SiO) m - (wherein R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group, and m is a number ranging from 1 to 1,000), which provides the silicone elastomer particles with appropriate hardness and flexibility.

[0034] From an industrial perspective, it is preferred that each R is independently a methyl group or a phenyl group, and m is preferably a number in the range of 10 to 800, more preferably a number in the range of 20 to 750.

[0035] [Component (B)] Component (B) is a component that introduces the above-mentioned polyorganosiloxane structure into the silicone elastomer particles by being crosslinked with component (A) through one or more reactions selected from a radical polymerization reaction and a hydrosilylation reaction of silicon-bonded hydrogen atoms.

[0036] Component (b1) is an organopolysiloxane component that is crosslinked by component (A) via a hydrosilylation reaction, and is characterized by having at least three silicon-bonded hydrogen atoms within the molecule. There are no particular restrictions on the bonding positions of these hydrogen atoms within the molecule.

[0037] Examples of organic groups other than hydrogen atoms that are bonded to silicon atoms contained in component (b1) include alkyl groups such as methyl, ethyl, propyl, butyl, and octyl groups, with methyl being preferred.Furthermore, examples of the molecular structure of the organohydrogenpolysiloxane of component (b1) include linear, branched, and branched cyclic structures, or a combination of one or more of these.Note that the number of silicon-bonded hydrogen atoms in one molecule is the average value for all molecules.

[0038] In particular, when component (b1) is a linear organopolysiloxane (organohydrogenpolysiloxane), if the silicone elastomer particles according to the present invention are placed in a biodegradable environment, the cross-linked structure is cleaved and the silicone elastomer particles are disintegrated, which facilitates decomposition into non-cross-linked linear organopolysiloxanes, thereby offering the advantage of facilitating reduction in environmental load and environmental risk.

[0039] The viscosity of component (b1) at 25°C is 1 to 1,000 mPa·s, and preferably 5 to 500 mPa·s. If the viscosity of component (b1) at 25°C is less than 1 mPa·s, component (b1) will be more likely to volatilize from the crosslinkable composition containing it, while if it exceeds 1,000 mPa·s, the curing time of the crosslinkable composition containing such component (a2) will be longer or this may cause poor curing. The component (a2) is not particularly limited, but examples thereof include a dimethylsiloxane-methylhydrogensiloxane copolymer both ends of which are capped with trimethylsiloxy groups, a dimethylsiloxane-methylhydrogensiloxane copolymer both ends of which are capped with dimethylhydrogensiloxy groups, a dimethylpolysiloxane both ends of which are capped with dimethylhydrogensiloxy groups, a methylhydrogenpolysiloxane both ends of which are capped with trimethylsiloxy groups, a cyclic methylhydrogenpolysiloxane, and a cyclic methylhydrogensiloxane-dimethylsiloxane copolymer.

[0040] Here, the molar ratio of the carbon-carbon double bonds (Alk) in component (A1) to the silicon-bonded hydrogen atom content (H) in component (b1) (i.e., the reactivity ratio in the hydrosilylation reaction), H / Alk, is preferably in the range of 0.7 to 1.2. The lower limit of H / Alk is preferably 0.80 or more, 0.85 or more, 0.90 or more, or 0.95 or more, and the upper limit is 1.15 or less, and more preferably 1.10 or less, or 1.05 or less. If the upper limit of H / Alk exceeds the above-mentioned value, unreacted silicon-bonded hydrogen atoms are likely to remain after the reaction. Conversely, if the upper limit of H / Alk is less than the above-mentioned value, unreacted silicon-bonded hydrogen atoms and their (meth)acrylic terminal groups are likely to remain after the reaction. Because these are curing reactive groups, if a large amount remains in the particles, they can cause crosslinking reactions between particles over time, resulting in aggregation and poor dispersion of the obtained oil-containing silicone elastomer particles, and if reactive hydrogen atoms remain, they can cause the generation of flammable hydrogen gas over time. Particularly preferably, when the H / Alk value is 0.9 to 1.1, and especially close to 1.0, the curing reactive groups are completely consumed, the crosslinking reaction is terminated, and aggregation between particles over time can be effectively suppressed.

[0041] Since component (b2) forms a crosslinked structure through a radical reaction with component (A), it is necessary for the component (b2) to have an average of at least three (meth)acryloxy group-containing organic groups per molecule. If the component (b2) has an average of two or fewer (meth)acryloxy group-containing organic groups per molecule, a sufficient crosslinked structure may not be formed, and practical silicone elastomer particles may not be obtained.

[0042] More specifically, the (meth)acryloxy group-containing organic group is a (meth)acryloxy group bonded to a silicon atom via a divalent organic group, and is represented by the formula: —R ２ -O-C(=O)-C(R ３ ) = CH ２ {In the formula, R ２ is an alkylene group having 1 to 20 carbon atoms or (CH ２ ) ｐ -Si(CH ３ ) ２ —O—Si(CH ３ ) ２ - (CH ２ )ｑ (wherein p and q are each a number ranging from 1 to 20), and R ３ is a hydrogen atom or a methyl group.}.

[0043] R in the formula ２ The alkylene group represented by (CH ２ ) ｐ -Si(CH ３ ) ２ —O—Si(CH ３ ) ２ - (CH ２ ) ｑ The divalent linking group represented by the formula (I) is a divalent linking group having a siloxane converter structure, and industrially, examples thereof include linking groups in which p and q are each independently a number from 3 to 6.

[0044] Preferably, component (b2) is a linear organopolysiloxane represented by the following structural formula:

[0045] In formula (1), R １１ are each independently an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms (e.g., methyl group), an aryl group having 6 to 22 carbon atoms (e.g., phenyl group), or a hydroxyl group, and are preferably a methyl group or a phenyl group industrially. ａ is the above-mentioned (meth)acryloxy group-containing organic group, and is particularly preferably a (meth)acryloxy group bonded to a silicon atom via the above-mentioned alkylene group or a divalent linking group having a siloxane converter structure. １１ or R ａ where m is a number of 1 or more, and n is a number of 1 or more. However, component (a) has at least three R ａ Since the (meth)acryloxy group-containing organic group represented by the formula (I) is contained, when m=1, R is R ａThat is, the linear organopolysiloxane represented by the above structural formula has R at one end and side chain, only at the side chain, or at both end and side chain of the siloxane molecule. ａ and preferably an organopolysiloxane having a (meth)acryloxy group-containing organic group represented by the formula: and containing at least three (meth)acryloxy group-containing organic groups in the molecule.

[0046] m+n is the degree of siloxane polymerization of the linear organopolysiloxane molecule excluding the terminal siloxane structure, and from the standpoints of handling as a raw material, emulsification properties, and disintegration into fine linear siloxane molecules upon biodegradation, m+n is preferably in the range of 10 to 800, more preferably 20 to 600, and particularly preferably 30 to 500. Furthermore, it is particularly preferable that m+n be a number that results in a viscosity of component (a) of 20 to 10,000 mPa s at 25°C.

[0047] Component (C) is a curing agent, and is selected from (c1) a radical polymerization initiator and (c2) a hydrosilylation reaction catalyst, depending on the selection of component (A) and the reaction system.

[0048] Component (c1) is a radical initiator that promotes the radical polymerization or radical copolymerization reaction of the above-mentioned components (a1) and (B). Examples of the radical initiator include conventionally known compounds generally used in radical polymerization methods, such as azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy-2-ethylhexanoate, and tert-hexylperoxy-2-ethylhexanoate; and persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate. These radical initiators may be used alone or in combination of two or more.

[0049] The amount of radical initiator (c1) used is preferably in the range of 0.1 to 5 parts by mass per 100 parts by mass of the combined total of components (a1) and (B). In particular, when component (c1) is a water-soluble persulfate such as potassium persulfate, it has the advantage of being extremely easy to add and react with, especially when crosslinking in water crosslinkable silicone emulsion particles obtained by emulsifying a crosslinkable silicone composition prepared by a radical polymerization reaction in water. Furthermore, when completing the radical polymerization reaction, it is particularly preferable to add aminomethylpropanediol or the like in the range of 0.1 to 5 parts by mass for the purpose of terminating the reaction and neutralizing the solution to adjust the pH.

[0050] The timing of adding component (c1) to the crosslinkable composition can be selected depending on the method for forming the silicone elastomer particles, and it may be added to the composition in advance, or component (a1) or component (B) may be supplied from different spray lines and component (c1) may be added to either one of them and mixed during spraying. The silicone elastomer particles of the present invention are preferably prepared via an aqueous suspension formed by emulsification in water, and component (c1) may be added to the crosslinkable silicone composition in advance, or an emulsion containing component (c1) may be added separately to water.

[0051] During the polymerization reaction of the crosslinkable silicone composition, a chain transfer agent can be optionally added. Specific examples of this chain transfer agent include mercapto compounds such as 2-mercaptoethanol, butyl mercaptan, n-dodecyl mercaptan, 3-mercaptopropyltrimethoxysilane, and polydimethylsiloxane having a mercaptopropyl group; and halides such as methylene chloride, chloroform, carbon tetrachloride, butyl bromide, and 3-chloropropyltrimethoxysilane.

[0052] Component (c2) is a hydrosilylation catalyst that promotes the addition reaction (hydrosilylation reaction) between the carbon-carbon double bonds contained in the alkenyl terminal groups present in the crosslinkable composition and silicon-bonded hydrogen atoms. Preferred hydrosilylation catalysts are those containing platinum-based metals, and specific examples include chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, complexes of chloroplatinic acid and ketones, complexes of chloroplatinic acid and vinylsiloxanes, platinum tetrachloride, platinum fine powder, solid platinum supported on an alumina or silica carrier, platinum black, olefin complexes of platinum, alkenylsiloxane complexes of platinum, carbonyl complexes of platinum, and platinum catalysts containing these platinum-based catalysts in powders of thermoplastic organic resins such as methyl methacrylate resins, polycarbonate resins, polystyrene resins, and silicone resins. In particular, platinum alkenylsiloxane complexes such as a complex of chloroplatinic acid and divinyltetramethyldisiloxane, a complex of chloroplatinic acid and tetramethyltetravinylcyclotetrasiloxane, a platinum divinyltetramethyldisiloxane complex, and a platinum tetramethyltetravinylcyclotetrasiloxane complex are preferably used. Note that non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt may also be used as catalysts for promoting the hydrosilylation reaction.

[0053] The amount of component (c2) added to the crosslinkable composition may be any catalytic amount, and typically, the amount is preferably such that the amount of platinum-based metal contained in component (c2) is in the range of 1 to 1,000 ppm, more preferably in the range of 5 to 500 ppm, relative to the total mass of the crosslinkable composition. The amount of platinum metal in the silicone elastomer particles may also be reduced by the method proposed by the present inventors in JP 2014-122316 A.

[0054] The timing of adding component (c2) to the crosslinkable composition can be selected depending on the method for forming the silicone elastomer particles, and it may be added to the composition in advance, or component (A) or component (B) may be supplied from different spray lines and component (c2) may be added to either one of them and mixed during spraying. The oil-containing silicone elastomer particles of the present invention are preferably prepared via an aqueous suspension formed by emulsification in water, and component (c2) may be added to the crosslinkable silicone composition in advance, or a separate emulsion containing component (c2) may be added to water.

[0055] The crosslinkable silicone composition may contain a cure retarder, typically a hydrosilylation reaction inhibitor. Examples of such cure retarders include acetylene compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds. Specific compounds include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 2-phenyl-3-butyn-2-ol, and 1-ethynyl-1-cyclohexanol (ETCH); 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 3-methyl-3-penten-1-yne; and 3,5-dimethyl-3-hexen-1-yne and other ene-yne ​​compounds; and alkenylsiloxanes such as 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, methyl(tris(1,1-dimethyl-2-propynyloxy))silane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane. The amount added is within a range of 0.001 to 5 parts by mass per 100 parts by mass of component (a), but can be appropriately determined depending on the type of cure retarder used, the properties and amount of the hydrosilylation reaction catalyst used, and other factors.

[0056] The cross-linking reactive silicone composition may contain one or more polymerization inhibitors from the standpoint of preventing unintended side reactions. For example, it may contain one or more selected from hindered phenol-based polymerization inhibitors, hydroquinone-based polymerization inhibitors, and catechol-based polymerization inhibitors. The amount used can be selected appropriately, but the total concentration of the polymerization inhibitors relative to the sum of the components (A) to (C) is preferably 50 ppm by mass or less, and more preferably 30 ppm by mass or less.

[0057] The crosslinkable silicone composition may contain components other than those described above, provided that the technical effects of the present invention are not impaired. For example, the crosslinkable silicone composition may contain organic solvents such as aliphatic hydrocarbons such as n-hexane, cyclohexane, and n-heptane; aromatic hydrocarbons such as toluene, xylene, and mesitylene; ethers such as tetrahydrofuran and dipropyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; antioxidants such as phenols, quinones, amines, phosphorus compounds, phosphites, sulfur compounds, and thioether compounds; light stabilizers such as triazoles and benzophenones; flame retardants such as phosphate esters, halogen compounds, phosphorus compounds, and antimony compounds; one or more antistatic agents such as cationic surfactants, anionic surfactants, and nonionic surfactants; dyes; pigments.

[0058] The silicone elastomer particles of the present invention may optionally further have (i) a structure in which a part or all of their surfaces are coated with one or more materials selected from organopolysiloxane resins, silica, and other silicone elastomer particles; (ii) a mesoporous structure; (iii) a structure containing an oil agent that is liquid at 40°C; and (iv) a structure crosslinked by silalkylene groups having 2 to 20 carbon atoms, and optional components that impart these structures may be used in combination.

[0059] [Hardness of Silicone Elastomer] While the hardness of silicone elastomer particles cannot be measured directly, it can be measured indirectly by curing the crosslinkable silicone composition used to form the silicone elastomer particles, which is the raw material for the silicone elastomer particles. Specifically, the crosslinkable reactive silicone composition can be cured into a sheet without being emulsified in water, and the hardness of the silicone elastomer sheet can be measured using a JIS A hardness scale as specified in JIS K6301. The hardness of the silicone elastomer according to the present invention varies depending on the type of crosslinkable silicone composition, the amount of components (a) and (b) used, and the crosslink density, but is preferably in the range of 10 to 80. Other preferred hardness values ​​are as described above.

[0060] [Formation of Silicone Elastomer Particles and Production Method Thereof] The silicone elastomer particles of the present invention can be produced by a method comprising the step of curing cross-linkable reactive silicone emulsion particles obtained by emulsifying the cross-linkable silicone composition used to form the silicone elastomer particles in water in the presence of a curing agent (C) to obtain spherical silicone elastomer particles.

[0061] The crosslinkable silicone composition used to form the silicone elastomer particles can be mixed uniformly using mechanical force such as a mixer.

[0062] In this method, silicone elastomer particles can be obtained by emulsifying the above-mentioned crosslinkable silicone composition in an aqueous surfactant solution and curing it. Furthermore, particle size can be easily adjusted by adjusting the emulsion particle size. Examples of surfactants include nonionic, anionic, cationic, betaine, and water-soluble polymers such as polyvinyl alcohol. The particle size of the resulting silicone elastomer particles varies depending on the type and content of the surfactant. To prepare small-sized silicone elastomer particles, the amount of surfactant added is preferably within the range of 0.5 to 50 parts by weight per 100 parts by weight of the crosslinkable silicone composition.

[0063] To uniformly disperse the crosslinkable silicone composition in water in the form of crosslinkable reactive silicone emulsion particles, it is preferable to use an emulsifier, such as a homomixer, paddle mixer, Henschel mixer, homodisper, colloid mill, propeller agitator, homogenizer, in-line continuous emulsifier, ultrasonic emulsifier, or vacuum kneader.

[0064] The aqueous dispersion of crosslinkable silicone emulsion particles prepared by the above method can then be heated or left at room temperature to cure the crosslinkable silicone emulsion particles in the aqueous dispersion, thereby preparing an aqueous dispersion of silicone elastomer particles. When such an aqueous dispersion is heated, from the standpoint of hydrosilylation reactivity or radical polymerization reactivity, the heating temperature is preferably 100°C or less, and particularly preferably 10 to 95°C. Methods for heating the aqueous dispersion containing crosslinkable silicone emulsion particles include, for example, directly heating the aqueous dispersion or adding the aqueous dispersion to hot water. The liquid crosslinkable silicone emulsion particles cure in water through the crosslinking reaction, forming an aqueous dispersion of silicone elastomer particles.

[0065] The silicone elastomer particles of the present invention thus obtained can be used as an aqueous dispersion (aqueous suspension) as is. In particular, they may be used as a cosmetic raw material in the form of this aqueous suspension, and this is preferred. When blended into cosmetics that use an aqueous solution as a dispersion medium (e.g., hair cosmetics), blending the silicone elastomer particles of the present invention as an aqueous dispersion may facilitate uniform dispersion of the silicone elastomer particles, thereby achieving the desired performance and feel.

[0066] Preferably, the silicone elastomer particles of the present invention can be isolated by removing water from an aqueous dispersion of silicone elastomer particles. Methods for removing water from the aqueous dispersion include, for example, drying using a vacuum dryer, a hot air circulation oven, or a spray dryer. The heating and drying temperature of the spray dryer must be appropriately set based on the heat resistance and crosslinking temperature of the silicone elastomer particles. To prevent secondary aggregation of the resulting microparticles, it is preferable to control the temperature of the silicone elastomer particles below their glass transition temperature. The silicone elastomer particles thus obtained can be recovered using a cyclone, a bag filter, or the like. As a pretreatment for this operation, the dispersion may be concentrated by methods such as thermal dehydration, filtration, centrifugation, and decantation, and, if necessary, the dispersion may be washed with water.

[0067] The silicone elastomer particles of the present invention may be subjected to a surface treatment as needed, which may further improve the aggregation suppression effect of the silicone elastomer particles of the present invention. Furthermore, surface treatment with other known hydrophilic or hydrophobic treatment agents may also be performed. Optionally, as described above, the obtained silicone elastomer particles may be further coated in part or in whole with inorganic fine particles such as silica, silicone resin, or the like. Furthermore, the obtained silicone elastomer particles may be crushed or disintegrated using mechanical force as needed, or may be classified using known techniques.

[0068] Furthermore, silicone elastomer particles obtained through such a manufacturing process may be able to further improve the appearance, spreadability, and feel of the cosmetic, particularly when used as a cosmetic ingredient, and particles obtained by this manufacturing method tend to be more suitable for solving the problems of the present invention. Thus, one of the preferred modes for achieving the technical effects of the present invention can and appropriately be defined by the manufacturing process.

[0069] The silicone elastomer particles according to the present invention are not particularly limited in their average primary particle size, but from the standpoints of imparting a smooth feel and comfortable sensation to cosmetics, not causing poor appearance, and ensuring storage stability and blending stability as a cosmetic ingredient, the average primary particle size measured by laser diffraction scattering is preferably in the range of 0.5 to 20 μm, and more preferably 0.5 to 15 μm. The particle size of the silicone elastomer particles can be controlled by the crushing / classification process of the crosslinked reactive silicone emulsion particles and the resulting silicone elastomer particles.

[0070] The shape of the silicone elastomer particles according to the present invention may be, for example, spherical, true spherical, ellipsoidal, or irregular, with spherical and true spherical shapes being particularly preferred. Spherical silicone elastomer particles can be easily obtained by preparing the silicone elastomer particles in the form of an aqueous suspension, as described below, and drying them using a vacuum dryer, a hot air circulation oven, or a spray dryer.

[0071] Furthermore, in the present invention, when the crosslinkable silicone composition used to form the silicone elastomer particles is cured into a sheet, it is preferable that the JIS-A hardness, as measured using a JIS-A hardness scale specified in JIS K6301, be in the range of 10 to 80. When the JIS-A hardness of the rubber sheet obtained by curing the crosslinkable silicone composition into a sheet falls within this range, the resulting silicone elastomer particles are likely to be sufficiently suppressed in aggregation and to be rich in fluidity, dispersibility, silky feel, smoothness, and softness. Furthermore, by selecting this JIS-A hardness, it is possible to design or predict, to a certain extent, the feel, texture, and handling properties of the silicone elastomer particles when incorporated into cosmetics, and it is also possible to improve stress relaxation properties when incorporated into organic resins. When the silicone elastomer particles of the present invention are used as a cosmetic ingredient or a stress relaxation agent for organic resins, it is particularly preferable to use silicone elastomer particles having a JIS-A hardness in the range of 30 to 80, particularly 50 to 80.

[0072] Optionally, the silicone elastomer particles of the present invention may have a structure in which the surface thereof is partially or entirely coated with one or more materials selected from organopolysiloxane resins, silica, and other silicone elastomer particles, which may be expected to further reduce cohesion, control oil absorption, improve feel, etc.

[0073] Optionally, the silicone elastomer particles of the present invention may have a mesoporous structure having fine pores.

[0074] Optionally, the silicone elastomer particles of the present invention may contain an oil that is liquid at 40° C. The oil can be easily incorporated into the silicone elastomer particles by emulsifying it together with the cross-linking reactive silicone composition described below, and the inclusion of the oil can be expected to further reduce cohesion, control oil absorption, improve feel, and the like.

[0075] [Cosmetic Raw Materials and Cosmetic Compositions] The silicone elastomer particles of the present invention are useful as cosmetic raw materials. When blended into cosmetic compositions and the like, they are soft and have an outstanding effect of improving the feel and sensation of use of cosmetics and the like, and are remarkably easy to handle as a cosmetic raw material and have excellent storage stability and incorporation stability into systems.

[0076] In particular, the silicone elastomer particles of the present invention have the advantages of being superior in feel and texture compared to known silicone particles, offering a high degree of freedom in formulation design, and when incorporated into cosmetics, not absorbing oily ingredients over time to cause thickening or a change in feel, and when applied to skin or hair, suppressing the oiliness and stickiness of the cosmetics, imparting smooth spreadability and a soft and moist feel, and improving compatibility with the skin, resulting in an excellent feel when used.In addition, when used in combination with UV protection ingredients, the silicone elastomer particles of the present invention may be able to improve the UV protection effect of cosmetics without impairing the feel and texture of the cosmetics compared to other powders or existing silicone elastomer particles.

[0077] Furthermore, the silicone elastomer particles of the present invention have performance equal to or better than that of conventionally known silicone elastomer particles, but are active in biodegradable reactions, and in a biodegradable environment, the cross-linked structure formed between silicon atoms in the silicone elastomer particles at least partially cleaves, and the primary particles of the silicone elastomer particles are disintegrated, generating non-cross-linked polyorganosiloxanes, so they are a material with low risk and environmental load to the global environment.Furthermore, they can be used in place of conventionally known silicone elastomer particles, and are extremely versatile.

[0078] Cosmetic compositions containing the silicone elastomer particles of the present invention are not particularly limited in type, but examples include cleansing cosmetics such as soap, body shampoo, and facial cleanser; basic cosmetics such as lotions, creams, emulsions, and packs; base makeup cosmetics such as powder and foundation; eyebrow cosmetics such as lipstick, blusher, eye shadow, eyeliner, and mascara; makeup cosmetics such as nail polish; hair cosmetics such as shampoo, hair rinse, hair styling products, hair growth agents, hair care products, and hair dyes; aromatic cosmetics such as perfumes and eau de colognes; toothpaste; bath additives; and specialty cosmetics such as depilatories, shaving lotions, antiperspirants, deodorants, and sunscreens. These cosmetic compositions may be formulated in aqueous liquid, oily liquid, emulsion, cream, foam, semi-solid, solid, or powder form. These cosmetic compositions can also be used as a spray.

[0079] In these cosmetic compositions, the content of the silicone elastomer particles is preferably within the range of 0.5 to 99.0% by mass, and particularly preferably within the range of 1.0 to 95% by mass, because if the content of the silicone elastomer particles exceeds the upper limit of the range, the cosmetic effect is lost, and if it is below the lower limit of the range, it is difficult to improve the feel of use of the cosmetic composition.

[0080] The silicone elastomer particles of the present invention can be used to replace part or all of the silicone particles in cosmetic compositions (particularly the formulation examples) containing silicone particles (such as silicone rubber powder) or silicone composite particles proposed in the above-mentioned Patent Documents 1 (JP H07-316014A), Patent Document 2 (International Patent Publication WO2017 / 191798), and Patent Document 3 (JP H02-243612A), JP 2011-105663A, JP 2011-168634A, JP 2011-102354A, and JP 2014-122316A, and may further improve the usability and production efficiency of the cosmetic compositions proposed in these patent documents. Needless to say, examples of cosmetic compositions containing silicone particles (such as silicone rubber powder) or silicone composite particles that can be blended with the silicone elastomer particles of the present invention are not limited to those described above. It is also possible to design formulations in which part or all of the silicone particle components in commercially available cosmetics are replaced with the silicone elastomer particles of the present invention using techniques commonly used by those skilled in the art.

[0081] Furthermore, the silicone elastomer particles of the present invention can be used to replace part or all of the silicone particles in the applications and formulations of cosmetic compositions disclosed in the above patent documents, etc., and such uses are encompassed within the scope of the present invention. For example, the silicone elastomer particles of the present invention may be used in combination with optional ingredients such as a cosmetic medium (aqueous medium or oily medium), an oily medium (including oils and volatile oils), water, colorants, pigments, UV protection ingredients, alcohols, water-soluble polymers, film-forming agents, oils, oil-soluble gelling agents, organically modified clay minerals, surfactants, resins, salts, moisturizers, preservatives, antibacterial agents, antioxidants, pH adjusters, chelating agents, cooling agents, anti-inflammatory agents, skin-beautifying ingredients (skin-whitening agents, cell activators, agents for improving rough skin, blood circulation promoters, skin astringents, antiseborrheic agents, etc.), vitamins, amino acids, nucleic acids, hormones, inclusion compounds, etc., physiologically active substances, active pharmaceutical ingredients, fragrances, etc., by selecting the same method and quantitative ranges as those disclosed in Patent Document 2 (International Patent Publication No. WO2017 / 191798).

[0082] In particular, the silicone elastomer particles of the present invention are superior in usability, feel, handling, storage stability, dispersibility, and high oil absorption properties to those of conventionally known silicone particles, silsesquioxane-coated silicone composite particles, and oil-containing silicone particles, and therefore can achieve particularly favorable appearance, usability, etc. in the following: (1) cosmetic compositions and formulations containing an oily medium (oily cosmetic ingredient) such as an oily agent, (2) cosmetic compositions and formulations containing a lipophilic UV protection component (e.g., octyl paramethoxycinnamate, etc.), and (3) cosmetic compositions and formulations containing an inorganic powder such as a colorant or pigment. These specific formulations will be described in more detail in the examples and subsequent sections.

[0083] In addition, because the silicone elastomer particles of the present invention allow for easy design of aqueous dispersions, they offer excellent formulation design freedom and blend stability, even in aqueous cosmetic compositions and formulations, making it possible to achieve a favorable feel when used. Specific formulations for these will be described in more detail in the examples and subsequent sections.

[0084] The cosmetic preparation of the present invention can be easily produced by simply uniformly mixing the cosmetic raw material of the present invention as described above with other cosmetic raw materials. Various mixing and kneading devices commonly used in the production of cosmetics can be used as mixing means. Examples of such devices include a homomixer, paddle mixer, Henschel mixer, homodisper, colloid mixer, propeller agitator, homogenizer, in-line continuous emulsifier, ultrasonic emulsifier, and vacuum kneader.

[0085] [Organic Resin Additives and Organic Resins, Paints, and Coating Agents] The silicone elastomer particles of the present invention have the above-mentioned properties, making them extremely useful as organic resin additives. Specifically, the silicone elastomer particles of the present invention have excellent uniform dispersibility in organic resins and, if desired, excellent stress relaxation properties, and are less likely to aggregate even after long-term storage, resulting in significantly excellent handling and storage stability. Furthermore, the members, paint films, or coating films obtained by curing organic resins containing the silicone elastomer particles have improved flexibility (including the softness of the coating layer), durability, and adhesion and conformability to substrates, and are particularly excellent in flexibility and thermal shock resistance, making them extremely useful as high-performance organic resins, paints, or coating agents used in electronic materials.

[0086] [Organic Resin] Suitable examples of organic resins containing the silicone elastomer particles of the present invention include curable organic resin compositions and thermoplastic resins. Of these, curable resins are suitable for electronic materials such as semiconductor substrates. More specifically, examples of curable organic resin compositions include phenolic resins, formaldehyde resins, xylene resins, xylene-formaldehyde resins, ketone-formaldehyde resins, furan resins, urea resins, imide resins, melamine resins, alkyd resins, unsaturated polyester resins, aniline resins, sulfone-amide resins, silicone resins, epoxy resins, and copolymer resins of these resins. Two or more of these curable resins can also be combined. In particular, the curable resin is preferably at least one selected from the group consisting of epoxy resins, phenolic resins, imide resins, and silicone resins. The epoxy resin may be any compound containing a glycidyl group or an alicyclic epoxy group, and examples thereof include o-cresol novolac type epoxy resins, phenol novolac type epoxy resins, biphenyl type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, naphthol aralkyl type epoxy resins, polyvinylphenol type epoxy resins, diphenylmethane type epoxy resins, diphenylsulfone type epoxy resins, triphenolalkane type epoxy resins, cresol-naphthol co-condensation type epoxy resins, bisphenylethylene type epoxy resins, fluorene type epoxy resins, stilbene type epoxy resins, spirocoumarone type epoxy resins, norbornene type epoxy resins, terpene type epoxy resins, phenolcyclohexane type epoxy resins, halogenated epoxy resins, imide group-containing epoxy resins, maleimide group-containing epoxy resins, allyl group-modified epoxy resins, and silicone-modified epoxy resins. Examples of the phenolic resin include polyvinylphenol type, phenol novolak type, naphthol type, terpene type, phenol dicyclopentadiene type, phenol aralkyl type, naphthol aralkyl type, triphenol alkane type, dicyclopentadiene type, cresol-naphthol co-condensation type, and xylene-naphthol co-condensation type.Examples of silicone resins include epoxy-modified silicone resins obtained by reacting an epoxy resin with a silanol group or a silicon-bonded alkoxy group in the silicone resin. Examples of the curing mechanism of such curable resins include heat curing, high-energy ray curing such as ultraviolet light or radiation, moisture curing, condensation reaction curing, and addition reaction curing. The state of such curable resins at 25°C is not limited, and they may be either liquid or solid that softens when heated.

[0087] The organic resin containing the silicone elastomer particles of the present invention can contain other optional components such as curing agents, curing accelerators, fillers, photosensitizers, higher fatty acid metal salts, ester waxes, plasticizers, etc. Examples of the curing agents include organic acids such as carboxylic acids and sulfonic acids and their anhydrides; organic hydroxy compounds; organosilicon compounds having silanol groups, alkoxy groups, or halogeno groups; primary or secondary amino compounds, and these can also be used in combination of two or more. Examples of the curing accelerator include tertiary amine compounds, organometallic compounds such as aluminum and zirconium; organophosphorus compounds such as phosphines; heterocyclic amine compounds, boron complex compounds, organic ammonium salts, organic sulfonium salts, organic peroxides, and hydrosilylation catalysts. Examples of fillers include fibrous fillers such as glass fiber, asbestos, alumina fiber, ceramic fiber containing alumina and silica, boron fiber, zirconia fiber, silicon carbide fiber, metal fiber, polyester fiber, aramid fiber, nylon fiber, phenolic fiber, and natural animal and plant fibers; and particulate fillers such as fused silica, precipitated silica, fumed silica, calcined silica, zinc oxide, calcined clay, carbon black, glass beads, alumina, talc, calcium carbonate, clay, aluminum hydroxide, barium sulfate, titanium dioxide, aluminum nitride, silicon carbide, magnesium oxide, beryllium oxide, kaolin, mica, and zirconia, and these may be used in combination. In the case of epoxy resins, it is particularly preferable to include an amine-based curing agent.

[0088] The silicone elastomer particles of the present invention may be incorporated as an additive into thermoplastic resins other than those mentioned above, and may be used as a physical property modifier (e.g., surface lubricant or stress relief agent) or an optical property modifier (e.g., light scattering agent). The type of thermoplastic resin is not particularly limited, and may be at least one polymer selected from the group consisting of polycarbonate resins, polyester resins, polyether resins, polylactic acid resins, polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, polystyrene resins, styrene copolymers, fluorine-containing polymers such as tetrafluoroethylene, polyvinyl ethers, and cellulose polymers, or a composite resin composed of a combination thereof. The silicone resin-coated silicone elastomer particles of the present invention can be uniformly dispersed in these thermoplastic resins (including masterbatches) using a mixing device such as a twin-screw or single-screw extruder or kneader / mixer, and may be molded into a desired shape, such as a film, for use.

[0089] The amount of silicone elastomer particles of the present invention added can be selected appropriately depending on the physical properties required of the organic resin, but is generally in the range of 0.1 to 30 parts by mass, and may be in the range of 0.5 to 10 parts by mass, per 100 parts by mass of organic resin. If the amount of the particles added is less than the lower limit, performance such as stress relaxation properties for the resin may be insufficient, and the flexibility and thermal shock resistance of the resulting cured organic resin, particularly the thermal shock resistance after moisture absorption, tend to be reduced. On the other hand, if the amount exceeds the upper limit, the organic resin or paint / coating agent may thicken after blending, reducing handling and workability, and the mechanical properties of the resulting cured organic resin tend to be reduced.

[0090] Furthermore, since the silicone elastomer particles of the present invention have excellent stress relaxation properties when blended with organic resins, they may be blended with epoxy resins, etc. for printed wiring boards to form prepregs. Furthermore, copper foil with a filler particle-containing resin layer for printed wiring boards may be formed by providing a resin layer containing the silicone elastomer particles of the present invention on one side of the copper foil, and used in copper-clad laminates (CCLs).

[0091] [Paints and Coating Agents] Paints and coating agents containing the silicone elastomer particles of the present invention can be exemplified by room temperature curing types, room temperature drying types, and heat curing types, and depending on their properties, they can be water-based, oil-based, and powder-based. Furthermore, depending on the vehicle resin, examples include polyurethane resin paints, butyral resin paints, long oil phthalic acid resin paints, alkyd resin paints, amino alkyd resin paints consisting of amino resins and alkyd resins, epoxy resin paints, acrylic resin paints, phenolic resin paints, silicone-modified epoxy resin paints, silicone-modified polyester resin paints, and silicone resin paints.

[0092] The amount of silicone elastomer particles of the present invention added can be selected appropriately depending on the physical properties required of the paint or coating agent, but in order to impart a uniform and soft matte finish to the resulting paint film, it is preferably in the range of 0.1 to 150 parts by mass, more preferably 0.1 to 100 parts by mass, and particularly preferably 0.1 to 50 parts by mass, or 0.1 to 20 parts by mass, per 100 parts by mass of the solids content of the paint. If the amount of the particles added is less than the above-mentioned lower limit, the matte finish, adhesion, stress relaxation properties, and other performance characteristics of the paint film may be insufficient, while if the amount exceeds the above-mentioned upper limit, the organic resin or paint or coating agent after blending may thicken, reducing handling and workability.

[0093] Paints and coating agents containing the silicone elastomer particles of the present invention may contain alcohols such as methanol and ethanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate and cellosolve acetate; amides such as N,N-dimethylformamide; olefins such as hexane, heptane and octane; organic solvents such as aromatic hydrocarbons such as toluene and xylene; known inorganic fillers such as reinforcing silica, organic fillers, curing accelerators, silane coupling agents, pigments such as carbon black, dyes, antioxidants, thickeners made of polymeric compounds, flame retardants, and weather resistance imparting agents.

[0094] [As an eco-friendly material] As mentioned above, the silicone elastomer particles of the present invention are different from conventional non-biodegradable thermoplastic resin particles and silicone particle materials, and are expected to have biodegradable properties in that, in a biodegradable environment, the cross-linked structure formed between silicon atoms in the silicone elastomer particles at least partially cleaves, and the primary particles of the silicone elastomer particles are disintegrated, accompanied by the generation of non-cross-linked polyorganosiloxanes.Therefore, they can be used as "eco-friendly" cosmetic raw materials and industrial raw materials that have low environmental load and environmental risk and comply with regulations such as microplastics, and can be expected to be able to appeal to users and general consumers who are concerned about the impact on the global environment as "eco-friendly" materials with biodegradability.

[0095] The biodegradable silicone elastomer particles and their production method according to the present invention will be explained in detail using examples and comparative examples. However, the present invention is not limited to these examples. The viscosity values ​​in the examples are values ​​at 25°C. The properties of each silicone particle were measured as follows. Unless otherwise specified in the examples, silicone particles are a general term for particles made of a silicone cured product (cured silicone particles) and do not include emulsions.

[0096] [Average Primary Particle Diameter of Emulsion Particles] The emulsion before the addition of the radical polymerization initiator and before the addition of the hydrosilylation catalyst was measured using a laser diffraction particle size distribution analyzer (LS-230 manufactured by Beckman Coulter), and the median diameter (particle size corresponding to 50% of the cumulative distribution, 50% particle size) was taken as the average particle size.

[0097] [Average secondary particle diameter of silicone particles (powder)] Using ethanol as a dispersion medium, the particle diameter of cured silicone particles was measured using a laser diffraction particle size distribution analyzer (Malvern Panalytical's Mastersizer 3000), and the median diameter (particle diameter corresponding to 50% of the cumulative distribution, D90, μm) and arithmetic dispersity (indicating the degree of dispersion of the particle size distribution, SD, μm2) of the cured silicone particles in ethanol were obtained. To prepare a measurement sample, cured silicone particles (1 g) and ethanol (100 mL) were dispersed in a 300 mL cup using a stirring blade and an ultrasonic vibrator.

[0098] Synthesis Example 1: Alkenyl-Modified Polycaprolactone Compound No. 1 A four-neck separable flask was charged with 35.12 parts by weight of Pluronic L-31 (manufactured by ADEKA Corporation, diol-type polyoxyethylene-polyoxypropylene copolymer, molecular weight: approximately 1100), 49.70 parts by weight of chloroform, and 0.22 parts by weight of triazabicyclodecene. 14.58 parts by weight of ε-caprolactone was added dropwise while aerating with N2. The mixture was stirred at room temperature for 4 hours. After the reaction, 0.38 parts by weight of benzoic acid was added. After leaving the mixture overnight, the chloroform was removed under reduced pressure while bubbling with N2, yielding a transparent polymer. 83.21 parts by weight of the resulting polymer and 16.79 parts by weight of vinylsilazane were charged. The mixture was heated to 50°C while bubbling with N2, and 0.02 parts by weight of trifluoromethanesulfonic acid was added and allowed to react for 4 hours. After filtration, minor components were removed by bubbling with N2, yielding a transparent polymer. H-NMR and Si-NMR analyses of the polymer revealed peaks attributable to vinylsiloxy groups, indicating that a polycaprolactone (alkenyl-modified EOPO polycaprolactone compound No. 1) with terminal vinylsiloxy groups had been obtained, with the following structure: (In the formula, m+n=4.0, a+b=18)

[0099] Example 1: Silicone Elastomer Particles No. 1 (Hydrosilylation Reaction Type) Linear organohydrogenpolysiloxane (viscosity 55 mm2 / s) and alkenyl-modified polycaprolactone compound No. 1 were uniformly mixed at room temperature in a mass ratio of 15:85. This composition was then dispersed in a 25°C aqueous solution consisting of 0.5 parts by mass of polyoxyethylene alkyl (C12-14) ether and 30 parts by mass of pure water, and further uniformly emulsified using a colloid mill. The mixture was then diluted with 526 parts by mass of pure water to prepare an emulsion. Next, an isopropyl alcohol solution of chloroplatinic acid (an amount sufficient to provide 10 ppm by mass of platinum metal in the composition) was added to the emulsion as an aqueous dispersion of polyoxyethylene alkyl (C12-14) ether and pure water, and the mixture was stirred. The emulsion was then allowed to stand at 50°C for 4 hours to prepare a uniform aqueous suspension of elastomer particles. Next, this aqueous suspension was filtered, and the residue was dried in an oven at 50°C for 5 hours to obtain silicone elastomer particles No. 1. The average primary and secondary particle sizes of the obtained silicone elastomer particles were 0.95 μm and 30.2 μm, respectively.

[0100] Synthesis Example 2: Methacrylic-Modified Silicone Polymer: A four-neck separable flask was charged with 91.03 parts by weight of octamethylcyclosiloxane, 0.01 parts by weight of MEHQ (hydroquinone monomethyl ether, polymerization inhibitor), and 6.54 parts by weight of 3-methacryloxypropylmethyldimethoxysilane. The mixture was heated while stirring at 200 rpm and aerating 2% O₂N₂. When the mixture reached 50°C, 0.05 parts by weight of trifluoromethanesulfonic acid and 1.52 parts by weight of water were added. After reacting at 55°C for 1 hour, the mixture was heated to 70°C. The pressure was further reduced to 100 mmHg, and the by-product methanol was removed for approximately 1 hour. Then, 0.85 parts by weight of hexamethyldisiloxane and a trace amount of water were added, and the mixture was reacted for 3 hours. After the reaction, ammonia gas was bubbled through the mixture to neutralize the trifluoromethanesulfonic acid, and the resulting salt was removed by diatomaceous earth filtration. The filtrate was treated under reduced pressure at 150°C for 3 hours to remove volatile components. C, Si-NMR analysis revealed that (a1-1) a methacrylic-modified silicone polymer was obtained with 214 dimethylsiloxane units, 5 methacrylic group-introduced siloxane units, and a viscosity of 472 mPas. (wherein m=5, n=214) is a methacrylic-modified silicone polymer (viscosity at 25° C.: 472 mPas).

[0101] Synthesis Example 3: Acrylic-modified crosslinked sorbitan monolaurate: A four-neck separable flask was charged with 35.37 parts by weight of sorbitan monolaurate and 45.18 parts by weight of chloroform. The mixture was stirred at room temperature while aerating with nitrogen, and 9.81 parts by weight of adipoyl chloride was added dropwise so that the heat generation would be 30°C or less. After reacting at room temperature for 5 hours, 9.63 parts by weight of potassium carbonate was added and the mixture was reacted for 1 hour. Excess potassium carbonate was removed by filtration. The resulting solution was heated to 70°C. The pressure was further reduced to 100 mmHg, and the chloroform was removed for about 1 hour. The pressure was then reduced to 5 mmHg, and the chloroform was removed for 2 hours at 70°C. A four-neck separable flask was charged with 33.94 parts by weight of the resulting crosslinked sorbitan monolaurate, 44.66 parts by weight of chloroform, 0.05 parts by weight of MEHQ (hydroquinone monomethyl ether, polymerization inhibitor), and 10.63 parts by weight of potassium carbonate. While stirring at room temperature and aerating with 2% O2 and N2, 10.71 parts by weight of acryloyl chloride was added dropwise so that the temperature did not exceed 30°C, and the mixture was allowed to react at room temperature for 5 hours. Water was added until the solution was neutral using pH test paper. The mixture was heated to 70°C, the pressure was reduced to 100 mmHg, and the chloroform was removed for approximately 1 hour. The pressure was then reduced to 5 mmHg, and the chloroform was removed at 70°C for 2 hours. H-NMR and C-NMR analysis revealed that the polymer had the following structure: a (meth)acrylic-modified sorbitan lauryl compound, in which the acrylic group was modified to a sorbitan lauryl ester crosslinked with adipoyl chloride. (R' is a lauryl group)

[0102] Example 2: Silicone Elastomer Particles No. 2 (Radical Polymerization Type) The methacrylic-modified silicone polymer and (meth)acrylic-modified polysorbitan lauryl compound were uniformly mixed at room temperature in a mass ratio of 17.2:82.8. This composition was then dispersed in a 25°C aqueous solution consisting of 0.27 parts by mass of GOHSENOL EG-05C, 0.53 parts by mass of GOHSENOL EG-18P, and 46 parts by mass of pure water. The resulting mixture was then uniformly emulsified using a colloid mill and diluted with 526 parts by mass of pure water to prepare an emulsion. The mixture was heated in a 1-L flask until the temperature reached 70°C, at which point an aqueous solution of 0.5 g of potassium persulfate (Sigma-Aldrich) in 9.5 g of water was added dropwise over 1 minute. The emulsion was stirred at 70°C for 3 hours and then at 80°C for 2 hours to undergo radical polymerization, producing a uniform aqueous suspension of silicone rubber particles. Next, this aqueous suspension was filtered and washed with 200 ml of ethanol and 100 ml of acetone. The residue was dried in an oven at 70°C for 5 hours to obtain silicone elastomer particles No. 3. The average primary and secondary particle sizes of the obtained silicone elastomer particles were 2.84 μm and 318 μm, respectively.

[0103] Synthesis Example 4: Acrylic-Modified Polycaprolactone Compound A four-neck separable flask was charged with 42.79 parts by weight of Pluronic L-64 (manufactured by ADEKA Corporation, diol-type polyoxyethylene-polyoxypropylene copolymer, molecular weight: approximately 2900), 49.86 parts by weight of chloroform, and 0.10 parts by weight of triazabicyclodecene. 7.07 parts by weight of ε-caprolactone was added dropwise while aerating with N2. The mixture was stirred at room temperature for 4 hours. After the reaction, 0.18 parts by weight of benzoic acid was added. After leaving the mixture overnight, the chloroform was removed under reduced pressure by heating while bubbling with N2, yielding a transparent polymer. 44.53 parts by weight of the resulting polymer, 0.02 parts by weight of MEHQ (hydroquinone monomethyl ether, polymerization inhibitor), and 3.62 parts by weight of potassium carbonate were charged to a four-neck separable flask and stirred at room temperature. 3.65 parts by weight of acryloyl chloride was added dropwise so that the temperature did not exceed 30°C, and the mixture was allowed to react for 8 hours. After leaving the mixture overnight, the mixture was again allowed to react at room temperature for 8 hours. A small amount of water was added until the liquid became neutral as measured by pH test paper. A small amount of sodium sulfate was added, and the mixture was filtered. The resulting filtrate was heated to 70°C, the pressure was reduced to 100 mmHg, and the chloroform was removed for approximately 1 hour. The pressure was then reduced to 5 mmHg, and the chloroform was removed for 2 hours at 70°C. H-NMR and C-NMR analyses revealed that the polymer was a polycaprolactone ((meth)acrylic-modified polycaprolactone compound) whose terminals were modified with acrylic groups. (In the formula, m+n=4.0, a+b=43-45)

[0104] Example 3: Silicone Elastomer Particles No. 3 (Radical Polymerization Type)] The methacrylic-modified silicone polymer and (meth)acrylic-modified polycaprolactone compound No. 4 were mixed uniformly at room temperature in a mass ratio of 16.9:83.1. This composition was then dispersed in a 25°C aqueous solution consisting of 0.27 parts by mass of GOHSENOL EG-05C, 0.53 parts by mass of GOHSENOL EG-18P, and 46 parts by mass of pure water. The resulting mixture was then uniformly emulsified using a colloid mill and diluted with 526 parts by mass of pure water to prepare an emulsion. The mixture was heated in a 1-L flask until the temperature reached 70°C, at which point an aqueous solution of 0.5 g of potassium persulfate (Sigma-Aldrich) dissolved in 9.5 g of water was added dropwise over 1 minute. The emulsion was stirred at 70°C for 3 hours and then at 80°C for 2 hours to undergo radical polymerization, producing a uniform aqueous suspension of silicone rubber particles. Next, this aqueous suspension was filtered and washed with 200 ml of ethanol and 100 ml of acetone. The residue was dried in an oven at 70°C for 5 hours to obtain silicone elastomer particles No. 4. The average primary and secondary particle sizes of the obtained silicone elastomer particles were 15.24 μm and 592 μm, respectively.

[0105] Comparative Synthesis Example 1: (Meth)acrylic-Modified Polycaprolactone Compound No. C (without hydrophilic groups): A four-neck separable flask was charged with 18.81 parts by weight of Placel 205 (manufactured by Daicel Corporation, diol-type polycaprolactone, molecular weight: 530), 18.81 parts by weight of chloroform, 8.77 parts by weight of triethylamine, and 0.03 parts by weight of MEHQ (hydroquinone monomethyl ether, polymerization inhibitor). While stirring at 200 rpm and aerating with 2% O2-containing N2, 6.55 parts by weight of acryloyl chloride was added dropwise. The mixture was cooled in a water bath to prevent heat generation from exceeding 30°C. After the addition, the stirring time was extended by 1 hour. The liquid temperature was then raised to 50°C and aged for approximately 2 hours. Next, 28.21 parts by weight of water-1 was added and the mixture was stirred thoroughly. The mixture was then transferred to a separatory funnel, and the lower phase containing the modified polycaprolactone was removed. An additional 18.81 parts by weight of water-2 was added to homogenize the mixture. The mixture was then transferred to a separatory funnel and left overnight to allow for further separation. After overnight, the solution was removed and transferred to another four-neck flask. While bubbling with 2% O2-containing N2, the chloroform was removed under reduced pressure, yielding a transparent orange polymer. H-NMR analysis of the polymer revealed peaks attributable to acrylic groups, confirming that it was polycaprolactone ((meth)acrylic-modified polycaprolactone compound No. C) with the following structure: (In the formula, m+n=3.7)

[0106] Comparative Example 1: Silicone Elastomer Particles No. 4 (Radical Polymerization Type) A methacrylic-modified silicone polymer and (meth)acrylic-modified polycaprolactone Compound No. C were uniformly mixed at room temperature in a mass ratio of 30.0:70.0. This composition was then dispersed in a 25°C aqueous solution consisting of 0.27 parts by mass of GOHSENOL EG-05C, 0.53 parts by mass of GOHSENOL EG-18P, and 46 parts by mass of pure water. The mixture was then uniformly emulsified using a colloid mill and diluted with 526 parts by mass of pure water to prepare an emulsion. The mixture was heated in a 1-L flask until the temperature reached 70°C, at which point an aqueous solution of 0.5 g of potassium persulfate (Sigma-Aldrich) in 9.5 g of water was added dropwise over 1 minute. The emulsion was stirred at 70°C for 3 hours and then at 80°C for 2 hours to undergo radical polymerization, producing a uniform aqueous suspension of silicone rubber particles. Next, this aqueous suspension was filtered and washed with 200 ml of ethanol and 100 ml of acetone. The residue was dried in an oven at 70°C for 5 hours to obtain silicone elastomer particles No. 5. The average primary and secondary particle sizes of the obtained silicone elastomer particles were 3.41 μm and 31.1 μm, respectively.

[0107] The average primary particle size and average secondary particle size of each of the particles obtained in Examples 1 to 3 and Comparative Example 1 are summarized in Table 1 below.

[0108] [Cosmetic Formulation Examples] Below are examples of cosmetic formulations of the present invention that can incorporate silicone elastomer particles, which are one aspect of the present invention, although the present invention is not limited to these.

[0109] Examples 4 to 6, Comparative Example 2 The feel of use of loose powders using silicone elastomer particles with the compositions shown in Table 3 below was compared and evaluated by a panel of experts. (Preparation method) 1. Mix phase A. 2. Mix phase B. 3. Stir phase A and B until homogenous.

[0110] (Evaluation of Texture) The smoothness of the sample when applied to the inside of the forearm of 18 panelists was evaluated.

[0111] [Examples 7 to 9, Comparative Examples 3 and 4] The feel of use of water-in-oil sunscreens was comparatively evaluated by a panel, and the SPF and PA values ​​were also measured using an SPF analyzer. (Preparation method) Mix phase A. Mix phase B. While stirring phase A, slowly add phase B. Add phase C to the above 4 and stir until uniform.

[0112] (Evaluation of texture) Eighteen panelists applied the samples to the inside of their forearms and evaluated the spreadability and white residue.

[0113] (SPF Measurement) A sample (2 mg / cm2) was applied to a Helioplate HD6 manufactured by HelioScreen Labs, and the SPF and PA values ​​were measured using a UV-2000S manufactured by Labsphere (the values ​​are the average values ​​of 30 points, 10 measurement points each on 3 applied samples).

[0114] [Examples 10 to 12, Comparative Examples 5 and 6] The feel of use of water-in-oil foundations was comparatively evaluated by a panel. (Preparation method) Mix phase A. Mix phase B. Mix phases A and B. While stirring phase AB, slowly add phase C. Add phase D to the above 4 and stir until uniform.

[0115] (Evaluation of texture) Eighteen panelists applied the samples to the inside of their forearms and evaluated the spreadability and moist feeling.

[0116] [Example 13, Comparative Examples 7 and 8] The feel of use and blurring effect of oil-in-water wrinkle concealing creams were compared and evaluated. (Preparation method) Mix phase A. Mix phase B. While stirring phase A, slowly add phase B. Add phase C to the above 4 and stir until uniform.

[0117] (Evaluation of texture) Eighteen panelists applied the samples to the inside of their forearms and evaluated the spreadability and moist feeling.

[0118] (Blurring effect) The silicone elastomer particles according to the examples of the present invention were applied to a glass slide to a thickness of 10 microns, and the blurring effect was judged based on the degree of blurring of the letters below the glass slide. The silicone elastomer particles according to the examples of the present invention showed good results in all cosmetic compositions.

[0119] <Enzymatic Degradation Test of Silicone Elastomer Particles> [Examples 1-3 (Silicone Elastomer Particles No. 1-3), Comparative Example 1 (Silicone Elastomer Particles No. 4), and Existing Silicone Elastomer Products] 0.1 g of each of the prepared silicone elastomer particles and an existing "our silicone elastomer (product)" (manufactured by Dow-Toray Industries, Inc., product name: EP-9610 Cosmetic Powder; silicone elastomer particles obtained by hydrosilylation of alkenyl-modified polysiloxane and organohydrogenpolysiloxane) was weighed and placed in an Eppendorf tube. Type XIII lipase derived from Pseudomonas bacteria was mixed with 0.1 M phosphate-buffered saline (pH 7.4) to prepare an 8 U / mL enzyme solution. 1 mL of the resulting enzyme solution was added to each tube to prepare test specimens. The test specimens were placed in a 37°C oven, and the test was continued for up to 96 hours, with the enzyme replaced every 24 hours. After the specified time, each sample was removed, washed with water, dried overnight, and then completely dried in a vacuum oven. The weight of the sample after complete drying was measured, and the weight loss rate was defined as the decomposition rate. The enzymatic decomposition test (test time - decomposition rate %) is shown in Figure 1.

[0120] The silicone elastomer particles according to these Examples all show a weight loss over time in the presence of enzymes, suggesting that they are degradable. In particular, the silicone elastomer particles according to Examples 1 to 3 all show a high decomposition rate of over 10% after 96 hours, suggesting that the silicone elastomer particles according to the Examples of the present application are highly expected to be biodegradable. On the other hand, our existing silicone elastomers do not exhibit biodegradability, and the silicone elastomer particles according to the Comparative Example, which do not have hydrophilic groups in their crosslinked portions, exhibited a decomposition rate inferior to that of Examples 1 to 3.

Claims

1. The biodegradable silicone elastomer particles have a structure in which at least two silicon atoms in the silicone elastomer particles are crosslinked by a divalent organic group containing a hydrophilic group, and in the silicone elastomer particles, -(R ２ SiO) ｍ - (wherein R is an alkyl group having 1 to 20 carbon atoms which is unsubstituted or substituted by a halogen atom, an aryl group having 6 to 22 carbon atoms or a hydroxyl group, and m is a number in the range of 1 to 1000), and have a polyorganosiloxane structure represented by the formula.

2. The structure crosslinked by a divalent organic group containing a hydrophilic group is such that (A1) both ends of the molecular chain are R Ａｌｋ R ２ SiO (wherein R Ａｌｋ is a carbon-carbon double bond-containing organic group and R is an alkyl group or an aryl group) and is blocked with a hydrosilylation-reactive silyl group, and contains a hydrophilic group in the molecule, and a crosslinking agent (A2) having at least two radically polymerizable functional groups in the molecule and containing a hydrophilic group in the molecule. The biodegradable silicone elastomer particles according to claim 1, which are derived from at least one crosslinking agent selected therefrom.

3. The biodegradable silicone elastomer particles according to claim 2, wherein the component (A1) is a crosslinking agent containing a polyether structure in the molecule (a1-1), and the component (A2) is a sorbitan fatty acid ester or a polyoxyalkylene sorbitan fatty acid ester having at least two radically polymerizable functional groups in the molecule (a2-1), and one or more crosslinking agents selected from crosslinking agents containing at least two radically polymerizable functional groups and a polyether structure in the molecule (a2-2).

4. The biodegradable silicone elastomer particles according to claim 2, wherein the component (A1) is a crosslinking agent containing a polyoxyethylene-polyoxypropylene block copolymer structure in the molecule (a1-1-1), and the component (A2) is a sorbitan laurate, sorbitan stearate, sorbitan oleate, polyoxyethylene sorbitan oleate having at least two radically polymerizable functional groups in the molecule (a2-1-1), and one or more crosslinking agents selected from crosslinking agents containing at least two radically polymerizable functional groups and a polyoxyethylene-polyoxypropylene block copolymer structure in the molecule (a2-2-1).

5. (A) At least one crosslinking agent selected from the following components (A1) and (A2): (A1) Both ends of the molecular chain are R Ａｌｋ R １ ２ SiO (wherein, R Ａｌｋ (A1) is a carbon-carbon double bond-containing organic group, and R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group; and (A2) a crosslinking agent having at least two radically polymerizable functional groups and containing a hydrophilic group within the molecule; (B) at least one reactive organopolysiloxane selected from the following components (b1) and (b2), (b1) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms within the molecule, and (b2) an organopolysiloxane having at least three (meth)acryloxy group-containing organic groups, the at least one being selected from methacryloxy group-containing organic groups and acryloxy group-containing organic groups within the molecule.

3. The biodegradable silicone elastomer particles according to claim 1 or 2, which are silicone elastomer particles obtained by crosslinking in water crosslinkable reactive silicone emulsion particles obtained by emulsifying in water a crosslinkable reactive silicone composition which at least contains (C) one or more curing agents selected from (c1) a hydrosilylation reaction catalyst and (c2) a radical polymerization initiator and which is capable of being crosslinked by one or more reactions selected from a radical polymerization reaction and a hydrosilylation reaction of silicon-bonded hydrogen atoms.

6. (A1) Both ends of the molecular chain are R Ａｌｋ R １ ２ SiO (wherein, R Ａｌｋ (b1) a crosslinking agent which contains a hydrophilic group within the molecule and which is terminated with a hydrosilylation-reactive silyl group represented by the formula: (a) is a carbon-carbon double bond-containing organic group, and R is an unsubstituted or halogen-substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 22 carbon atoms, or a hydroxyl group; (b2) an organohydrogenpolysiloxane which has at least 3 silicon-bonded hydrogen atoms within the molecule; and (c3) a hydrosilylation reaction catalyst.

7. Crosslinkable reactive silicone composition emulsified in water by radical polymerization reaction containing a crosslinking agent having at least two radically polymerizable functional groups in the molecule (A2) and containing a hydrophilic group in the molecule; an organopolysiloxane having at least three (meth)acryloxy group-containing organic groups selected from methacryloxy group-containing organic groups and acryloxy group-containing organic groups in the molecule (b2); and a radical polymerization initiator (c2). The biodegradable silicone elastomer particles according to claim 1, characterized in that crosslinkable reactive emulsified particles are crosslinked in water.

8. The biodegradable silicone elastomer particles according to any one of claims 1 to 7, wherein the average primary particle diameter measured by the laser diffraction scattering method is 0.5 to 20 μm.

9. The biodegradable silicone elastomer particles according to any one of claims 1 to 7, wherein the JIS-A hardness measured by curing the radically polymerizable polycarbonate-modified silicone compound used for particle formation into a sheet form is in the range of 10 to 80.

10. The biodegradable silicone elastomer particles according to any one of claims 1 to 7, comprising a structure in which part or all of the surface thereof is coated with one or more selected from organopolysiloxane resins, silica, and other silicone elastomer particles.

11. The biodegradable silicone elastomer particles according to any one of claims 1 to 7, wherein the particles have a mesoporous structure.

12. The biodegradable silicone elastomer particles according to any one of claims 1 to 7, containing an oil agent that is liquid at 40°C in the particles.

13. The biodegradable silicone elastomer particles according to any one of claims 1 to 12, wherein the divalent organic group containing a hydrophilic group in the particles is active with respect to the biodegradation reaction, and in a biodegradable environment, the crosslinked structure formed between silicon atoms in the particles is at least partially cleaved, and the primary particles thereof have the property of being crushed with the generation of non-crosslinked polyorganosiloxane.

14. A cosmetic raw material containing the biodegradable silicone elastomer particles according to any one of claims 1 to 13.

15. A cosmetic composition containing the biodegradable silicone elastomer particles according to any one of claims 1 to 13.

16. An organic resin additive containing the biodegradable silicone elastomer particles according to any one of claims 1 to 13.

17. An organic resin containing the biodegradable silicone elastomer particles according to any one of claims 1 to 13.

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