Ion-release composite particles and method for producing ion-release composite particles

Abstract

To provide an ion sustained-release composite particle that has suppressed acid reactivity and also has excellent ion sustained-releasability.SOLUTION: An ion sustained-release composite particle comprises ion sustained-release glass and a polymer compound, where the polymer compound includes a homopolymer or a copolymer of a (meth) acrylate compound having a hydroxyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to ion-releasing composite particles. [Background technology]

[0002] Fluoroaluminosilicate glass is known as an ion-releasing glass. By incorporating fluoroaluminosilicate glass into a dental composition, fluoride ions are released from the dental composition, which is expected to improve tooth quality. An example of such a dental composition is glass ionomer cement.

[0003] As other ion-releasing glasses, the applicant has created dental glass powders containing zinc, silicon, and fluorine, and compositions containing the glass powders (see, for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6783852 [Patent Document 2] Patent No. 6744399 [Patent Document 3] Patent No. 6633750 [Patent Document 4] Patent No. 6687731 Summary of the Invention [Problem to be solved by the invention]

[0005] However, ion-releasing glasses such as fluoroaluminosilicate glass and zinc-containing glass are highly reactive to acids, and therefore tend to cause problems with storage stability and hardening time when incorporated into dental compositions.

[0006] An object of the present invention is to provide controlled ion-release composite particles that have suppressed acid reactivity and good ion-release properties.is . [Means for solving the problem]

[0007] The ion-release composite particles according to one embodiment of the present invention are ion-release composite particles comprising an ion-release glass and a polymer compound, wherein the polymer compound comprises a copolymer of a (meth)acrylate compound having a hydroxyl group; The copolymer contains a monomer unit of a (meth)acrylate compound having a hydroxyl group and a monomer unit of a (meth)acrylate compound other than a (meth)acrylate having a hydroxyl group, and the (meth)acrylate compound other than a (meth)acrylate having a hydroxyl group is Contains a monomer unit of a difunctional (meth)acrylate compound, before The content of the bifunctional (meth)acrylate compound in the polymer compound is 10% by mass or more. 30 It is less than % by mass. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide controlled ion-release composite particles that have reduced acid reactivity and good ion-release properties. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail.

[0010] <Ion-releasing composite particles> The ion-releasing composite particles according to this embodiment include an ion-releasing glass and a polymer compound. In this specification, the term "ion-releasing" refers to the property of dissolving components contained in the glass and gradually releasing them in the form of ions. The composite particles are particles in which ion-releasing glass particles are composited with a polymer.

[0011] The ion-releasing glass contained in the ion-releasing composite particles is preferably glass containing at least one of zinc, calcium, lanthanum, and strontium.

[0012] The zinc content in the ion-releasing glass is not particularly limited, but for example, the zinc oxide (ZnO) content, calculated as oxide, is 3% by mass or more and 60% by mass or less, preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0013] By setting the ZnO content in the ion-releasing glass to 3% by mass or more, the zinc ion release from the ion-releasing glass can be increased, improving the effect of inhibiting tooth demineralization. Furthermore, by setting the ZnO content in the ion-releasing glass to 60% by mass or less, the viscosity of the ion-releasing glass can be reduced, improving the ease of use when the ion-releasing composite particles are used in a dental composition.

[0014] The content of calcium contained in the ion-releasing glass is not particularly limited, but for example, the content of calcium in the ion-releasing glass, calculated as oxide, as calcium oxide (CaO) is 1% by mass or more and 25% by mass or less, preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.

[0015] By setting the CaO content in the ion-releasing glass to 1% by mass or more, the calcium ion release from the ion-releasing glass can be increased, improving the effect of inhibiting tooth demineralization. Furthermore, by setting the CaO content in the ion-releasing glass to 25% by mass or less, the viscosity of the ion-releasing glass can be reduced, improving the ease of use when the ion-releasing composite particles are used in a dental composition.

[0016] The lanthanum content in the ion-releasing glass is not particularly limited, but for example, the content of lanthanum oxide (La2O3) calculated as oxide is 5% by mass or more and 60% by mass or less, preferably 15% by mass or more and 50% by mass or less, and more preferably 30% by mass or more and 40% by mass or less.

[0017] By making the content of La2O3 in the ion-releasing glass 5% by mass or more, the acid resistance of the glass is improved, and by making it 60% by mass or less, it becomes easier to produce powder of the ion-releasing glass.

[0018] The strontium content in the ion-releasing glass is not particularly limited, but for example, the content of strontium oxide (SrO) calculated as oxide is 5% by mass or more and 55% by mass or less, preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 45% by mass or less.

[0019] By setting the SrO content in the ion-releasing glass to 5% by mass or more, the strontium ion release from the ion-releasing glass can be increased, improving the effect of inhibiting tooth demineralization. Furthermore, by setting the SrO content in the ion-releasing glass to 55% by mass or less, the viscosity of the ion-releasing glass can be reduced, improving the ease of use when the ion-releasing composite particles are used in a dental composition.

[0020] The ion-releasing glass may contain aluminum, silicon, and fluorine as other components.

[0021] The aluminum content in the ion-releasing glass is not particularly limited, but for example, the content of aluminum oxide (Al2O3) calculated as oxide is from 0.1 to 30 mass%, preferably from 0.3 to 25 mass%, and more preferably from 0.5 to 20 mass%.

[0022] By making the Al2O3 content in the ion-releasing glass 0.1 mass % or more, the mechanical strength of the cured body is improved, and by making it 30 mass % or less, it becomes easier to produce powder of the ion-releasing glass.

[0023] The content of silicon (Si) in the ion-releasing glass is not particularly limited. For example, the content of silicon in the ion-releasing glass, calculated as oxide, in terms of silicon oxide (SiO2) is preferably 1% by mass or more and 65% by mass or less, more preferably 1% by mass or more and 60% by mass or less, and even more preferably 1% by mass or more and 55% by mass or less.

[0024] By setting the SiO2 content in the ion-releasing glass to 1 mass % or more, it becomes easier to obtain glass with high transparency, and by setting it to 65 mass % or less, it becomes easier to obtain a composition with appropriate curability.

[0025] The fluorine (F) content in the ion-releasing glass is not particularly limited and is from 1 to 30% by mass, preferably from 3 to 25% by mass, and more preferably from 4 to 20% by mass.

[0026] By setting the F content in the ion-releasing glass to 1% by mass or more, the sustained release of fluoride ions in the dental composition can be enhanced, the effect of inhibiting tooth demineralization can be improved, and caries prevention effects can be imparted. Furthermore, by setting the F content in the ion-releasing glass to 30% by mass or less, it becomes easier to adjust the viscosity of the ion-releasing glass.

[0027] The ion-releasing glass is preferably glass that is substantially free of phosphorus, or glass that contains only a small amount of phosphorus, even if it does contain phosphorus. In this specification, "substantially free of phosphorus" means that the target component such as phosphorus is not intentionally blended.

[0028] Note that the target component "substantially free" may be contained as an unavoidable impurity. If the target component is contained as an unavoidable impurity, the content of the target component is preferably less than 2% by mass. If a small amount of phosphorus is contained, the content of phosphoric acid (PO) calculated as an oxide is preferably 5% by mass or less.

[0029] In this embodiment, since the ion-releasing glass is substantially free of phosphorus, the released cations such as zinc ions and calcium ions are not trapped by phosphate ions, thereby improving the release of cations such as zinc ions and calcium ions.

[0030] It is more preferable that the ion-releasing glass is glass that is substantially free of sodium. In this embodiment, since the ion-releasing glass is substantially free of sodium, the released cations such as zinc ions and calcium ions are not trapped by sodium, and therefore the release of cations such as zinc ions and calcium ions can be improved.

[0031] The amount of ion-releasing glass in the ion-releasing composite particles is, for example, preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 80% by mass or less, and even more preferably 60% by mass or more and 70% by mass or less.

[0032] By making the amount of ion-releasing glass in the ion-releasing composite particles 40% by mass or more, it becomes easier to obtain the ion-releasing effect from a composition containing the ion-releasing composite particles, and by making it 90% by mass or less, it becomes easier to produce the ion-releasing composite particles.

[0033] The ion-releasing glass is preferably in the form of a powder (or powder). When the ion-releasing glass is in the form of a powder, the ion-releasing glass can be easily incorporated into a dental composition.

[0034] The particle size of the ion-releasing glass is, in terms of median diameter, from 0.02 μm to 30 μm, more preferably from 0.02 μm to 20 μm, and even more preferably from 0.02 μm to 20 μm. Here, the particle size refers to the average particle size defined by the median diameter.

[0035] When the particle size of the ion-releasing glass is 0.02 μm or more, the operability of the ion-releasing composite particles used in a dental composition is improved when the ion-releasing glass powder is used as a glass powder for the dental composition. Also, when the particle size of the ion-releasing glass is 30 μm or less, the wear resistance of the hardened dental composition is improved.

[0036] The polymer compound contained in the ion-release composite particles includes a homopolymer or copolymer of a (meth)acrylate compound having a hydroxyl group. In this specification, the term "(meth)acrylate" refers to at least one selected from acrylate and methacrylate.

[0037] In this specification, a homopolymer refers to a polymer mainly composed of structural units of a certain polymerization component. A copolymer refers to a polymer obtained by copolymerizing structural units of a certain polymerization component with structural units of other polymerization components. Note that homopolymers and copolymers may contain other polymerization components that are inevitably mixed in.

[0038] The polymer compound contained in the ion-release composite particles contains a homopolymer or copolymer of a (meth)acrylate compound having a hydroxyl group, which makes it possible to maintain good ion-release properties while suppressing the acid reactivity of the ion-release glass. As a result, when the ion-release composite particles are used in a dental composition, it is possible to prevent the hardening time of the dental composition from becoming shorter while maintaining good ion-release properties of the ion-release glass.

[0039] Examples of the (meth)acrylate compound having a hydroxyl group include hydroxyethyl methacrylate (HEMA), glycerin dimethacrylate (GDMA), bisphenol A diglycidyl methacrylate (Bis-GMA), etc. These (meth)acrylate compounds having a hydroxyl group may be used alone or in combination of two or more.

[0040] The content of the homopolymer or copolymer of the (meth)acrylate compound having a hydroxyl group in the polymer compound contained in the ion-controlled release composite particles is not particularly limited, and can be, for example, 50% by mass or more and 100% by mass or less in the polymer compound, preferably 60% by mass or more and 100% by mass or less, and more preferably 70% by mass or more and 100% by mass or less.

[0041] By making the content of a single polymer or copolymer of a (meth)acrylate compound having a hydroxyl group in the polymer compound contained in the ion-releasing composite particles 50 mass% or more, the acid reactivity of the ion-releasing glass can be sufficiently suppressed.

[0042] The copolymer of a (meth)acrylate compound having a hydroxyl group may contain a monomer unit of a (meth)acrylate compound other than the (meth)acrylate compound having a hydroxyl group.

[0043] Examples of other (meth)acrylate compounds contained as monomer units other than (meth)acrylates having a hydroxyl group include polyfunctional (meth)acrylate compounds, and among these, bifunctional (meth)acrylate compounds are preferred, such as ethoxylated bisphenol A dimethacrylate, di-2-methacryloyloxyethyl 2,2,4-trimethylhexamethylene dicarbamate (UDMA), triethylene glycol dimethacrylate (TEGDMA), etc. These bifunctional (meth)acrylate compounds may be used alone or in combination of two or more.

[0044] The content of the bifunctional (meth)acrylate compound contained as a monomer unit in the copolymer of the (meth)acrylate compound having a hydroxyl group in the polymer compound contained in the ion-release composite particles is not particularly limited, and can be, for example, 1% by mass or more and 40% by mass or less in the polymer compound, preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less.

[0045] By including a bifunctional (meth)acrylate other than a (meth)acrylate compound having a hydroxyl group as a monomer unit in the polymer compound contained in the ion-release composite particles, flexibility can be imparted to the ion-release composite particles while maintaining their mechanical strength.

[0046] The amount of the homopolymer or copolymer of the (meth)acrylate compound having a hydroxyl group in the ion-release composite particles is, for example, preferably 10% by mass or more and 45% by mass or less, more preferably 15% by mass or more and 40% by mass or less, and even more preferably 20% by mass or more and 30% by mass or less.

[0047] When the amount of a homopolymer or copolymer of a (meth)acrylate compound having a hydroxyl group in the ion-controlled release composite particles is 10% by mass or more, the effect of suppressing the acid reactivity of the ion-controlled release composite particles is improved, and when it is 45% by mass or less, the ion-controlled release property from the ion-controlled release composite particles is improved.

[0048] The ion-release composite particles of this embodiment may contain other components, such as a filler, a polymerization initiator, and a polymerization inhibitor, as long as the other components do not impair the object of the present invention.

[0049] The filler component is not particularly limited, but inorganic fillers are preferred, such as colloidal silica, fine particle silica whose surface has been hydrophobized, aluminum oxide (excluding aluminum oxide in ion-releasing glass), etc. These fillers may be used alone or in combination of two or more.

[0050] The amount of filler in the ion-release composite particles is, for example, preferably 0.01% by mass or more and 30% by mass or less, more preferably 0.05% by mass or more and 20% by mass or less, and even more preferably 0.1% by mass or more and 10% by mass or less.

[0051] When the amount of filler in the ion-releasing composite particles is 0.01% by mass or more, the dispersibility of the ion-releasing glass in the dental composition is improved, and when it is 30% by mass or less, the amount of ion-releasing glass can be increased.

[0052] The polymerization initiator is not particularly limited, but examples thereof include azobisisobutyronitrile (AIBN).

[0053] The content of the polymerization initiator in the ion-release composite particles is not particularly limited, but is, for example, 0.01 to 3% by mass, preferably 0.03 to 2% by mass, and more preferably 0.05 to 1% by mass. When the content of the polymerization initiator in the ion-release composite particles is 0.01 to 3% by mass, the effect of suppressing the acid reactivity of the ion-release glass is stable, and the ion-release properties of the ion-release glass are stable.

[0054] The polymerization inhibitor is not particularly limited, but examples thereof include 2,6-di-tert-butyl-p-cresol.

[0055] The content of the polymerization inhibitor in the ion-release composite particles is not particularly limited, but is, for example, 0.01% by mass to 5% by mass, preferably 0.05% by mass to 3% by mass, and more preferably 0.1% by mass to 2% by mass. When the content of the polymerization inhibitor in the ion-release composite particles is 0.01% by mass to 5% by mass, the effect of suppressing the acid reactivity of the ion-release glass is stable, and the ion-release properties of the ion-release glass are stable.

[0056] The use of the ion-release composite particles of this embodiment is not particularly limited, and they can be used, for example, in various dental materials. Here, examples of dental materials include dental cements, dental adhesives, dental temporary sealing materials, dental primers, dental coating materials, dental composite resins, dental hard resins, dental cutting resin materials, dental temporary restorative materials, dental fillers, and dentifrices. Among these, the ion-release composite particles are preferably used in dental temporary sealing materials.

[0057] <Method for producing ion-releasing composite particles> The method for producing ion-release composite particles according to this embodiment is a method for producing ion-release composite particles containing ion-release glass and a polymer compound, and includes a step of polymerizing and curing a mixture containing the ion-release glass and a (meth)acrylate compound having a hydroxyl group. The method for producing ion-release composite particles according to this embodiment is essentially the method for producing the ion-release composite particles of this embodiment described above.

[0058] The ion-releasing glass and the polymer compound which is a (meth)acrylate compound having a hydroxyl group used in the method for producing the ion-releasing composite particles of this embodiment can be the ion-releasing glass and the (meth)acrylate compound having a hydroxyl group contained in the ion-releasing composite particles of this embodiment described above.

[0059] In the method for producing ion-releasing composite particles according to this embodiment, in the step of polymerizing and curing a mixture (hereinafter referred to as the mixture) containing ion-releasing glass and a (meth)acrylate compound having a hydroxyl group (hereinafter referred to as the polymerization step), it is preferable that the mixture further contains a polymerization initiator.

[0060] The polymerization initiator is not particularly limited, but examples thereof include azobisisobutyronitrile (AIBN).

[0061] The mixture preferably further contains a polymerization inhibitor.

[0062] The polymerization inhibitor is not particularly limited, but examples thereof include 2,6-di-tert-butyl-p-cresol.

[0063] The method for producing ion-release composite particles of this embodiment preferably further includes a silane treatment step in which the ion-release glass contained in the ion-release composite particles is silane-treated with a silane treating agent.

[0064] The silane treatment agent is not particularly limited, but examples thereof include 3-methacryloyloxypropyltrimethoxysilane.

[0065] In the method for producing ion-release composite particles of this embodiment, a mixture is polymerized and cured in a polymerization step to obtain a cured product (hereinafter referred to as a polymerized cured product). This polymerized cured product contains ion-release glass and a homopolymer or copolymer of a (meth)acrylate compound having a hydroxyl group. The polymerized cured product is crushed to produce ion-release composite particles.

[0066] The pulverization method is not particularly limited, and for example, a stamp mill, a planetary mill, or the like can be used.

[0067] The pulverized polymerized cured product (pulverized material) can be passed through a sieve to obtain controlled ion-releasing composite particles adjusted to a desired particle size.

[0068] The particle size of the ion-releasing glass to be adjusted is not particularly limited, but for example, the median diameter is 0.02 μm or more and 30 μm or less, more preferably 0.02 μm or more and 20 μm or less, and even more preferably 0.02 μm or more and 20 μm or less. [Example]

[0069] The present invention will be further described below with reference to examples. In the following, numerical values ​​without units or "%" are by mass (% by mass) unless otherwise specified.

[0070] <Ion-releasing glass> Glass Examples 1 to 6 having the compositions shown in Table 1 were prepared, and each glass was pulverized to obtain glass powder with a median diameter of 0.4 μm.

[0071] [Table 1]

[0072] <Silane-treated glass powder> The glass powder was annealed at 400° C. for 2 hours, then silanized with 4% 3-methacryloyloxypropyltrimethoxysilane, and dried at 110° C. for 3 hours to obtain silanized glass powders (Glass Examples 1 to 6).

[0073] [Examples 1 to 10 and Comparative Examples 1 to 12] Table 2 ~13 The silane-treated glass powder (glass examples 1 to 6) and other components (original liquid and R812) were mixed in the compositions shown in Table 2, degassed at 2000 rpm and 10 kPa, poured into a silicone mold, and heated at 90°C for 3 hours to polymerize. 、4、6、8、10、12 The component indicated by R812 in the table is fine particle silica surface-treated with hexamethyldisilazane (Aerosil (registered trademark) R812, manufactured by Nippon Aerosil Co., Ltd.). The obtained polymer (polymerized cured product) was pulverized in a stamp mill for 2 minutes and in a planetary mill at 150 rpm for 60 minutes, and then passed through a 200-mesh sieve to obtain composite powders (composite particles) of Examples 1 to 10 and Comparative Examples 1 to 12. In Comparative Examples 2, 4, 6, 8, 10, and 12, Glass Examples 1 to 6 were used as they were, respectively, without being composited with a polymer compound.

[0074] [Table 2]

[0075] [Table 3]

[0076] [Table 4]

[0077] [Table 5]

[0078] [Table 6]

[0079] [Table 7]

[0080] [Table 8]

[0081] [Table 9]

[0082] [Table 10]

[0083] [Table 11]

[0084] [Table 12]

[0085] [Table 13]

[0086] The ion-releasing properties and acid reactivity of the obtained composite powders (Examples 1 to 10 and Comparative Examples 1 to 12) were evaluated. The various tests and evaluations were carried out according to the following methods.

[0087] <Ion elution test of composite powder> 0.01 g of the composite powder was placed in a glass vial, and 10 mL of a 1:1 mixture of 0.2 mol / L lactic acid-sodium lactate buffer and methanol (pH 4.5) was added. The mixture was stirred for 24 hours and then centrifuged at 3000 rpm for 10 minutes. The filtrate was filtered through a 0.20 μm filter and the amount of ions was measured using an inductively coupled plasma (ICP) optical emission spectrometer (Thermo Fisher). The ion species measured were Zn 2+ , Ca 2+ , La 3+ , Sr 2+ is.

[0088] <Ion sustained release> In the ion elution test of the composite powder, zinc ions (Zn 2+ ), calcium ions (Ca 2+ ), lanthanum ion (La 3+ ), strontium ions (Sr 2+ ) was measured. With regard to the measured ion detection amount, for Examples 1 to 5 and Comparative Example 2, the percentage increase was calculated based on the ion detection amount of Comparative Example 1. For Examples 6 to 10 and Comparative Examples 4, 6, 8, 10, and 12, the percentage increase was calculated based on Comparative Examples 3, 5, 7, 9, and 11, respectively. The ion sustained release properties were evaluated according to the following evaluation criteria. Comparative Examples 1, 3, 5, 7, 9, and 11 were evaluated as unacceptable. The results are shown in Table 1. 14~19 Shown below. Good: 10% or more Not allowed: Less than 10%

[0089] <Acid reactivity> In a thermostatic chamber at 23°C and 50% humidity, the composite powder and an ion-releasing filler material (manufactured by GC Corporation, Caredyne (registered trademark) Restore Liquid) were mixed in a powder-liquid ratio of 1:1, and then kneaded for 30 seconds to obtain a kneaded mixture. The kneaded mixture was filled into a ring with a diameter of 8 mm and a height of 2 mm, and the exothermic peak of the kneaded mixture was observed using an infrared radiation pyrometer. The acid reactivity was evaluated according to the following evaluation criteria. The results of the acid reactivity are shown in Tables 14 to 19. Good: Peak temperature is less than 50% of that of Comparative Examples 2, 4, 6, 8, 10, or 12 (same glass examples not composited with polymer compounds). Unacceptable: Peak temperature is 50% or more of that of Comparative Examples 2, 4, 6, 8, 10, or 12 (same glass examples not composited with polymer compounds).

[0090] [Table 14]

[0091] [Table 15]

[0092] [Table 16]

[0093] [Table 17]

[0094] [Table 18]

[0095] [Table 19]

[0096] As can be seen from Table 4, composite particles containing ion-releasing glass and a polymer compound, in which the polymer compound contains a (meth)acrylate compound having a hydroxyl group, had good ion-releasing properties and acid reactivity (Examples 1 to 10).

[0097] In contrast, composite particles containing ion-releasing glass and a polymer compound, where the polymer compound did not contain a (meth)acrylate compound having a hydroxyl group, were unable to release ions sustainedly (Comparative Examples 1, 3, 5, 7, 9, and 11).

[0098] Moreover, the ion-releasing glass that was not composited with a polymer compound was not acid-reactive (Comparative Examples 2, 4, 6, 8, 10, and 12).

[0099] These results demonstrate that ion-releasing composite particles containing ion-releasing glass and a homopolymer or copolymer of a (meth)acrylate compound having a hydroxyl group as a polymer compound have suppressed acid reactivity and maintain ion-releasing properties.

[0100] Although the embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the invention described in the claims.

Claims

1. An ion-releasing composite particle comprising an ion-releasing glass and a polymer compound, the polymer compound includes a copolymer of a (meth)acrylate compound having a hydroxyl group, the copolymer contains a monomer unit of a (meth)acrylate compound having a hydroxyl group and a monomer unit of a (meth)acrylate compound other than a (meth)acrylate having a hydroxyl group, The (meth)acrylate compound other than the (meth)acrylate having a hydroxyl group contains a monomer unit of a bifunctional (meth)acrylate compound, the content of the bifunctional (meth)acrylate compound in the polymer compound is 10% by mass or more and 30% by mass or less; Ion-sustained release composite particles.

2. The ion-releasing glass is a glass containing at least one of zinc, calcium, lanthanum, and strontium. The ion-releasing composite particle according to claim 1 .

3. A method for producing ion-releasing composite particles containing ion-releasing glass and a polymer compound, comprising: a step of polymerizing and curing a mixture containing the ion-releasing glass, a (meth)acrylate compound having a hydroxyl group, and a (meth)acrylate compound other than a (meth)acrylate having a hydroxyl group, The (meth)acrylate compound other than the (meth)acrylate having a hydroxyl group includes a bifunctional (meth)acrylate compound, the content of the bifunctional (meth)acrylate compound in the polymer compound is 10% by mass or more and 30% by mass or less; Method for producing ion-releasing composite particles.

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