Hollow particles and use thereof

Abstract

The present invention provides hollow particles with which it is possible to suppress aggregation of hollow particles in a dispersion medium and prevent collapse of a hollow part due to deformation, and the use thereof. Specifically, the present invention provides hollow particles having a shell and a hollow portion surrounded by the shell, wherein the hollow particles have an esterified surface.

Description

Hollow particles and their uses

[0001] The present invention relates to hollow particles and uses thereof.

[0002] Conventionally, particles having voids inside have been used as microcapsule particles by incorporating various substances into the voids.

[0003] Particles having voids inside are also called hollow particles, and are used as light scattering materials, low reflectivity materials, heat insulating materials, low dielectric constant materials, and the like.

[0004] For example, Patent Documents 1 and 2 describe hollow particles obtained by preparing oil droplets containing a radical-reactive monomer and a hydrophobic organic solvent that has low compatibility with a polymer of the monomer in an aqueous solvent, and then polymerizing the oil droplets.

[0005] Furthermore, Patent Document 3 describes hollow organic-inorganic hybrid fine particles having an organic skeleton and an inorganic skeleton, a single-pore structure, an average particle diameter of 10 to 100 nm, a refractive index of 1.40 or less, and surface-treated with a silane coupling agent.

[0006] Japanese Patent Publication No. 2002-80503 Japanese Patent Publication No. 2005-215315 Japanese Patent Publication No. 2009-242475

[0007] The hollow particles described in Patent Documents 1 and 2 are not subjected to surface treatment or the like, and therefore are prone to aggregation in the dispersion medium.

[0008] The hollow particles described in Patent Document 3 are surface-treated with a silane coupling agent, but the dispersion of the hollow particles cannot be maintained in a highly hydrophobic dispersion medium, and aggregation may occur.

[0009] The present invention has been made in view of the above, and an object of the present invention is to provide hollow particles that can suppress aggregation of hollow particles in a dispersion medium and can prevent collapse of the hollow portions due to deformation, and uses thereof.

[0010] As a result of extensive research into achieving the above object, the present inventors have succeeded in developing the desired hollow particles and have found that the above object can be achieved by using these hollow particles. The present invention was completed as a result of further research.

[0011] The present invention provides the following aspects of the invention. Item 1. Hollow particles having a shell and a hollow portion surrounded by the shell, wherein the hollow particles have a surface that has been esterified. Item 2. The hollow particles according to Item 1, wherein the surface has been esterified with a phosphate ester compound. Item 3. The hollow particles according to Item 2, wherein the phosphate ester compound is a compound represented by the following formula (1): (In formula (1), R １ represents a linear or branched alkyl group having 3 to 19 carbon atoms, a linear or branched alkoxy group having 3 to 19 carbon atoms, an allyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, or a styryl group. ２represents a hydrogen atom or a methyl group. m represents a number of 0 or more and 30 or less. n represents 1 or 2.) Item 4. The hollow particle according to any one of Items 1 to 3, wherein the shell contains a (meth)acrylic resin, and the (meth)acrylic resin contains a polymer derived from a (meth)acrylic reactive monomer having an epoxy group and / or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group. Item 5. The hollow particle according to any one of Items 1 to 4, wherein the ratio η of the absorbance (A1100) to the absorbance (A1720) in an infrared absorption spectrum obtained by measuring the hollow particle by ATR-FTIR (absorbance ratio η: A1100 / A1720) is 0.800 or more and 2.000 or less. Item 6. The hollow particle according to any one of Items 1 to 5, wherein the shell contains an inorganic component. Item 7. Item 6. The hollow particles according to any one of items 1 to 6, having an average particle size of 10 to 200 nm. Item 8. The hollow particles according to any one of items 1 to 7, having a hollow ratio of 31.0 to 70% by volume. Item 9. A dispersion comprising the hollow particles according to any one of items 1 to 8. Item 10. A coating agent comprising the hollow particles according to any one of items 1 to 8. Item 11. A heat insulating film comprising the hollow particles according to any one of items 1 to 8. Item 12. An antireflection film comprising the hollow particles according to any one of items 1 to 8. Item 13. A light extraction film comprising the hollow particles according to any one of items 1 to 8. Item 14. A low dielectric constant film comprising the hollow particles according to any one of items 1 to 8. Item 15. A photosensitive resin composition comprising the hollow particles according to any one of items 1 to 8.

[0012] The hollow particles of the present invention can suppress aggregation of the hollow particles in a dispersion medium and can prevent collapse of the hollow portion due to deformation. Because of these excellent properties, the hollow particles of the present invention can be suitably used in a wide range of applications, such as dispersions, coating agents, heat insulating films, anti-reflection films, light extraction films, low dielectric constant films, and photosensitive resin compositions.

[0013] Preferred embodiments of the present invention will be described in detail below. The following description of the components may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0014] In this specification, the expressions "contain" and "comprise" include the concepts of "contain," "include," "consist essentially of," and "consist only of."

[0015] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "to" means a numerical range that includes the numbers before and after "to" as the upper and lower limits.

[0016] In this specification, "A and / or B" means "one of A and B" or "both A and B," and specifically means "A," "B," or "A and B."

[0017] In this specification, room temperature means a temperature within the range of 20°C to 25°C.

[0018] As used herein, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate.

[0019] In this specification, the term "(meth)acryloyl group" refers to an acryloyl group "CH ２ =CHC(=O)-" or methacryloyl group "CH ２ =C(CH ３ In this specification, the term "(meth)acryloyloxy group" refers to the acryloyloxy group "CH ２ ═CHC(═O)O—” or a methacryloyloxy group “CH ２ =C(CH ３ )C(=O)O-"

[0020] In this specification, the term "polymer derived from A monomer" means a polymer containing a structural unit derived from A monomer.

[0021] 1. Hollow Particles The hollow particles of the present invention have the following features (1) and (2): (1) The hollow particles have a shell and a hollow portion surrounded by the shell. (2) The hollow particles have a surface that has been subjected to an esterification treatment.

[0022] The hollow particles of the present invention have the above-mentioned features (1) and (2), and therefore can suppress aggregation of the hollow particles in a dispersion medium and prevent collapse of the hollow portions due to deformation. Here, "preventing collapse of the hollow portions due to deformation" means that the hollow particles maintain their spherical shape.

[0023] The hollow particles of the present invention preferably have a surface that has been esterified with a phosphate ester compound.

[0024] In one embodiment, the outer surface of the shell of the hollow particle is preferably esterified with a phosphoric acid ester compound.

[0025] In one embodiment, the hollow particles preferably have a shell and a hollow portion surrounded by the shell, and the phosphate ester compound is attached to the outer surface of the shell.

[0026] In one embodiment, the hollow particles preferably have a shell and a hollow portion surrounded by the shell, and at least a portion of the outer surface of the shell is coated with a phosphate ester compound.

[0027] In one embodiment, the hollow particles preferably have a shell and a hollow portion surrounded by the shell, and at least a portion of the outer surface of the shell is coated with a phosphate ester compound.

[0028] In one embodiment, it is even more preferable that the hollow particle has a shell and a hollow portion surrounded by the shell, and at least a portion of the outer surface of the shell is coated with a layer made of a phosphate ester compound.

[0029] In one embodiment, the phrase "the entire outer surface of the shell is coated with the phosphate ester compound" means that 100% of the outer surface of the shell is coated with the phosphate ester compound.

[0030] In one embodiment, "a portion of the outer surface of the shell is coated with a phosphate ester compound" means that typically 1% or more and less than 100% of the outer surface of the shell is coated with the phosphate ester compound.

[0031] In one embodiment, the phosphate ester compound is preferably attached to the outer surface of the shell via electrostatic interaction, van der Waals forces, chemical bonds, etc. The chemical bonds are not particularly limited, and examples thereof include covalent bonds, ionic bonds, coordinate bonds, chelate bonds, and hydrogen bonds.

[0032] In one embodiment, it is more preferable that the phosphate ester compound is attached to the outer surface of the shell via electrostatic interaction.

[0033] In one embodiment, it is preferable that the phosphate ester compound is chemically attached to the outer surface of the shell by an esterification reaction, and it is more preferable that the phosphate ester compound is attached via electrostatic interaction and the phosphate ester compound is chemically attached by an esterification reaction.

[0034] In one embodiment, the shell preferably has a phosphate ester compound chemically attached to its outer surface by an esterification reaction, and more preferably has a phosphate ester compound chemically attached by an esterification reaction and a phosphate ester compound attached via electrostatic interaction.

[0035] In one embodiment, at least a portion of the outer surface of the shell is preferably coated with a phosphate ester compound via electrostatic interaction, van der Waals forces, chemical bonding, etc. Here, the chemical bonding is not particularly limited, and examples thereof include covalent bonding, ionic bonding, coordinate bonding, chelate bonding, and hydrogen bonding.

[0036] In one embodiment, at least a portion of the outer surface of the shell is preferably coated with a phosphate ester compound via electrostatic interaction.

[0037] In one embodiment, at least a portion of the outer surface of the shell is preferably chemically coated with a phosphate ester compound by an esterification reaction, more preferably coated with a phosphate ester compound via electrostatic interaction and chemically coated with a phosphate ester compound by an esterification reaction.

[0038] In one embodiment, the mass ratio of the hollow particles to the phosphate ester compound (mass of hollow particles:mass of phosphate ester compound) is preferably 100:1 to 100:1000, more preferably 100:20 to 100:100, even more preferably 100:26 to 100:75, even more preferably 100:26.5 to 100:50, and even more preferably 100:27 to 100:40. A specific method for measuring this mass ratio (mass of hollow particles:mass of phosphate ester compound) will be described in the Examples section below.

[0039] In this embodiment, the phosphate ester compound is preferably a compound represented by the following formula (1): (In formula (1), R １ represents a linear or branched alkyl group having 3 to 19 carbon atoms (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), a linear or branched alkoxy group having 3 to 19 carbon atoms (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), an allyl group (CH ２ =CHCH ２ -), (meth)acryloyl group, (meth)acryloyloxy group, or styryl group (vinylphenyl group). ２ represents a hydrogen atom or a methyl group; m represents a number of 0 to 30; and n represents 1 or 2.

[0040] In the above formula (1), m is an oxyethylene group (—CH ２ CH ２ In other words, m is a value in the range necessary to give an added mole number of 0 to 30 when the entire compound represented by formula (1) is taken as 1 mole.

[0041] In the above formula (1), m is preferably 1 or more and 25 or less, more preferably 5 or more and 20 or less, and even more preferably 8 or more and 15 or less.

[0042] In the above formula (1), R ２ is preferably a hydrogen atom.

[0043] In the above formula (1), examples of the linear or branched alkyl group having 3 to 19 carbon atoms include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a cyclopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, and an n-nonadecyl group.

[0044] In the above formula (1), examples of the linear or branched alkoxy group having 3 to 19 carbon atoms include an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a neopentyloxy group, an n-hexyloxy group, a cyclohexyloxy group, an n-heptyloxy group, an n-octyloxy group, a 2-ethylhexyloxy group, a tert-octyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, an n-tridecyloxy group, an n-tetradecyloxy group, an n-pentadecyloxy group, an n-hexadecyloxy group, an n-heptadecyloxy group, an n-octadecyloxy group, and an n-nonadecyloxy group.

[0045] In the above formula (1), R １is preferably a linear or branched alkyl group having 3 to 19 carbon atoms (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), or a linear or branched alkoxy group having 3 to 19 carbon atoms (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), more preferably a linear or branched alkyl group having 10 to 19 carbon atoms (10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), or a linear or branched alkoxy group having 10 to 19 carbon atoms (10, 11, 12, 13, 14, 15, 16, 17, 18, or 19), Even more preferred is a linear or branched alkyl group having 13 carbon atoms, or a linear or branched alkoxy group having 13 carbon atoms, particularly preferred is a linear alkyl group having 13 carbon atoms, or a linear alkoxy group having 13 carbon atoms, and most preferred is a linear alkoxy group having 13 carbon atoms.

[0046] In one embodiment, a wide variety of known commercially available products can be used as the phosphate ester compound. Examples of commercially available products include Phosphanol ML-200, Phosphanol BH-650, Phosphanol ED-200, Phosphanol RA-600, Phosphanol ML-220, Phosphanol ML-240, Phosphanol RD-510Y, Phosphanol RS-410, Phosphanol RS-610, Phosphanol RS-710, Phosphanol RL-210, Phosphanol RL-310, Phosphanol RB-410, Phosphanol RP-710, and Phosphanol CP-120 (all manufactured by Toho Chemical Industry Co., Ltd.). These commercially available products can be used alone or in combination of two or more.

[0047] In the present embodiment, it is preferable that the shell contains a (meth)acrylic resin, and that the (meth)acrylic resin contains a polymer derived from a (meth)acrylic reactive monomer having an epoxy group and / or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group.

[0048] In the present embodiment, the (meth)acrylic resin preferably contains a polymer derived from a (meth)acrylic reactive monomer, and more preferably contains a polymer derived from a (meth)acrylic reactive monomer and a polymer derived from a crosslinkable monomer.

[0049] The (meth)acrylic resin preferably contains a polymer derived from a (meth)acrylic reactive monomer having an epoxy group and / or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group, and more preferably contains a polymer derived from a (meth)acrylic reactive monomer having an epoxy group.

[0050] The epoxy group and the oxetane group are functional groups that react with a compound having an amino group, a carboxy group, a chlorosulfone group, a mercapto group, a hydroxyl group, an isocyanate group, or the like to form a polymer.

[0051] Since the (meth)acrylic reactive monomer has an epoxy group or an oxetane group, a polymer having a crosslinked structure (crosslinked polymer) can be produced by radically polymerizing the (meth)acrylic reactive monomer having the epoxy group or the oxetane group and then reacting the epoxy group or the oxetane group with a crosslinkable monomer.

[0052] The (meth)acrylic reactive monomer usually has a (meth)acrylic reactive functional group. Examples of the (meth)acrylic reactive monomer include esters of (meth)acrylic acid and alcohols having 1 to 25 carbon atoms.

[0053] Examples of esters of (meth)acrylic acid with alcohols having 1 to 25 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, n-pentyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, iso-octyl (meth)acrylate, and n-nonyl (meth)acrylate, iso-decyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, iso-stearyl (meth)acrylate, phenoxyethylene glycol mono(meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. These esters can be used either alone or in combination of two or more.

[0054] The (meth)acrylic reactive monomer is preferably a reactive monomer having a (meth)acrylic reactive functional group and a non-(meth)acrylic reactive functional group.

[0055] Polymer particles can be produced by polymerizing a reactive monomer having a (meth)acrylic reactive functional group and a non-(meth)acrylic reactive functional group based on either of the two functional groups. The other functional group remaining in the polymer particles is reacted with a crosslinkable monomer, resulting in the polymer particles becoming polymers having a crosslinked structure (crosslinked polymers).

[0056] The (meth)acrylic reactive monomer is preferably a (meth)acrylic reactive monomer having an epoxy group or a (meth)acrylic reactive monomer having an oxetane group, more preferably a (meth)acrylic reactive monomer having an epoxy group.

[0057] Examples of the (meth)acrylic reactive monomer having an epoxy group or the (meth)acrylic reactive monomer having an oxetane group include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, (3-ethyloxetan-3-yl)methyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate. These monomers can be used alone or in combination of two or more. Note that glycidyl (meth)acrylate refers to glycidyl methacrylate (glycidyl methacrylate) and glycidyl acrylate (glycidyl acrylate).

[0058] In the present embodiment, the ratio η of the absorbance (A1100) to the absorbance (A1720) in the infrared absorption spectrum obtained by measuring the hollow particles by ATR-FTIR (absorbance ratio η: A1100 / A1720) is preferably 0.800 or more and 2.000 or less, more preferably 0.810 or more and 1.750 or less, still more preferably 0.820 or more and 1.500 or less, and still more preferably 0.825 or more and 1.250 or less.

[0059] In one embodiment, the lower limit of the absorbance ratio η (A1100 / A1720) may be 0.800, 0.805, 0.810, 0.815, 0.820, 0.825, or 0.830, and the upper limit of the absorbance ratio η (A1100 / A1720) may be 2.000, 1.900, 1.800, 1.700, 1.600, 1.500, 1.400, 1.300, 1.200, 1.100, or 1.000, and these upper and lower limit values ​​can be combined in any manner.

[0060] A specific method for measuring the absorbance ratio η (A1100 / A1720) will be explained in the examples below.

[0061] In this embodiment, the shell preferably comprises an inorganic component.

[0062] In one embodiment, the shell preferably contains a (meth)acrylic resin, and the (meth)acrylic resin preferably includes a polymer derived from a (meth)acrylic reactive monomer having an epoxy group or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group, and a polymer derived from a (meth)acrylic reactive monomer having a silyl group.

[0063] In one embodiment, the shell preferably contains a (meth)acrylic resin, and the (meth)acrylic resin preferably includes a polymer derived from a (meth)acrylic reactive monomer having an epoxy group or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group, a polymer derived from a (meth)acrylic reactive monomer having a silyl group, and a polymer derived from a crosslinkable monomer containing a nitrogen atom.

[0064] In one embodiment, the shell contains a (meth)acrylic resin, and the (meth)acrylic resin more preferably includes a polymer derived from a (meth)acrylic reactive monomer having an epoxy group or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group, a polymer derived from a (meth)acrylic reactive monomer having a silyl group, and a polymer derived from an amine compound (a polymer containing a structural unit derived from an amine compound).

[0065] In one embodiment, examples of the (meth)acrylic reactive monomer having a silyl group include 3-methacryloxypropyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, etc. These monomers can be used alone or in combination of two or more.

[0066] In one embodiment, the amine compound is preferably an aliphatic amine compound and / or a heterocyclic amine compound, more preferably an aliphatic amine compound.

[0067] Examples of the aliphatic amine compound include ethylenediamine, N,N,N',N'-tetramethylethylenediamine, propylenediamine, N,N,N',N'-tetramethylpropylenediamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, diethylenetriamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, triethylenetetramine, tetraethylenepentamine, 3,3'-diaminodipropylamine, butanediamine, pentanediamine, hexanediamine, trimethylhexanediamine, N,N,N',N'-tetramethylhexanediamine, bis(2-dimethylaminoethyl)ether, 2-[2-(dimethylamino)ethoxy]ethanol, triethanolamine, dimethylaminohexanol, and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxyspiro(5,5)undecane adduct. These aliphatic amine compounds may be used alone or in combination of two or more.

[0068] In one embodiment, the aliphatic amine compound is preferably ethylenediamine.

[0069] Examples of the heterocyclic amine compound include pyrrolidine, piperidine, piperazine, N-methylpiperazine, N,N'-dimethylpiperazine, N-aminoethylpiperazine, N,N',N'-trimethylaminoethylpiperazine, morpholine, methylmorpholine, ethylmorpholine, quinuclidine (1-azabicyclo[2.2.2]octane), triethylenediamine (1,4-diazabicyclo[2.2.2]octane), pyrrole, pyrazole, pyridine, hexahydro-1,3,5-tris(3-dimethylaminopropyl) (methyl)-1,3,5-triazine, 1,8-diazabicyclo-[5.4.0]-7-undecene, imidazole, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 5-ethylimidazole, 1-n-propylimidazole, 2-n-propylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, 1-n-butyl Imidazole, 2-n-butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-1H-imidazole, 2-heptadecyl-1H-imidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-phenylimidazole, 2-phenyl-1H-imidazole, 4-methyl-2-phenyl-1H-imidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole azole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-cyanoethyl-2-phenyl-4,Examples of heterocyclic amine compounds include 5-di(2-cyanoethoxy)methylimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, and 1-benzyl-2-phenylimidazole hydrochloride. These heterocyclic amine compounds can be used alone or in combination of two or more.

[0070] In one embodiment, the heterocyclic amine compounds are preferably piperazine and N-aminoethylpiperazine.

[0071] In this embodiment, the average particle size of the hollow particles is preferably 10 nm to 200 nm, more preferably 30 nm to 150 nm. If the average particle size of the hollow particles is 10 nm or more, aggregation of the hollow particles can be further suppressed, further improving handleability. If the average particle size of the hollow particles is 200 nm or less, scattering at the surface irregularities or particle interfaces can be further suppressed when the hollow particles are kneaded with a coating agent, resin, etc.

[0072] In this specification, the "average particle size of hollow particles" refers to the average particle size of hollow particles contained in a hollow particle dispersion. As the dispersion medium contained in the hollow particle dispersion, the dispersion medium exemplified in <Dispersion containing hollow particles> described later can be suitably used. The dispersion medium contained in the hollow particle dispersion is particularly preferably propylene glycol monomethyl ether acetate.

[0073] A specific method for measuring the average particle diameter of hollow particles will be described in the examples below.

[0074] In this embodiment, the lower limit of the average particle diameter of the hollow particles may be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm, and the upper limit of the average particle diameter of the hollow particles may be 200 nm, 190 nm, 180 nm, 170 nm, 160 nm, 150 nm, 140 nm, 130 nm, 120 nm, 110 nm, 100 nm, or 90 nm, and these upper and lower limit values ​​can be combined in any desired manner.

[0075] In this embodiment, the hollow particle preferably has a void ratio of 31.0 to 70% by volume.

[0076] In this specification, the "hollow ratio of hollow particles" means the hollow ratio of the binder of hollow particles, and the "hollow ratio of the binder of hollow particles" means the volume fraction (volume %) of air in hollow particles contained in the binder.

[0077] Examples of the binder include fluorine-based resins, polyamide resins, acrylic resins, polyurethane resins, acrylic urethane resins, and butyral resins. Among these, the binder is preferably an acrylic resin, more preferably a carboxyl group-containing acrylic resin, and even more preferably a liquid carboxyl group-containing acrylic resin. These binders can be used alone or in combination of two or more.

[0078] A specific method for measuring the binder hollowness of hollow particles will be described in the examples below.

[0079] In this embodiment, the lower limit of the hollow ratio of the hollow particles may be 31.0 vol%, 31.5 vol%, 32.0 vol%, 32.5 vol%, 33.0 vol%, 33.5 vol%, 34.0 vol%, or 34.5 vol%, and the upper limit of the hollow ratio of the hollow particles may be 70 vol%, 65 vol%, 60 vol%, 55 vol%, 50 vol%, 45 vol%, or 40 vol%, and these upper and lower limit values ​​can be combined in any manner.

[0080] In one embodiment, the shell preferably comprises at least one layer. In one embodiment, when the shell comprises at least one layer, the layer constituting the shell may comprise one layer, or may comprise two or more layers (e.g., two layers, three layers, four layers, etc.).

[0081] <Optional Additives> The hollow particles of the present invention may contain additives within the range that does not impair the effects of the present invention. Examples of additives include pigment particles (pigments), dyes, stabilizers, UV absorbers, antifoaming agents, thickeners, heat stabilizers, leveling agents, lubricants, and antistatic agents. These additives may be used alone or in combination of two or more.

[0082] The pigment particles are not particularly limited as long as they are pigment particles used in the relevant technical field. Specific examples of pigment particles include iron oxide pigments such as micaceous iron oxide and iron black; lead oxide pigments such as red lead and yellow lead; titanium oxide pigments such as titanium white (rutile titanium oxide), titanium yellow and titanium black; cobalt oxide; zinc oxide pigments such as zinc yellow; and molybdenum oxide pigments such as molybdenum red and molybdenum white. The pigment particles can be used alone or in combination of two or more.

[0083] <Dispersion containing hollow particles> Examples of the dispersion containing hollow particles according to this embodiment are described below.

[0084] In this embodiment, the dispersion liquid contains a dispersion medium and the hollow particles of this embodiment. The dispersion medium is not particularly limited as long as it is a liquid that does not completely dissolve the hollow particles of this embodiment.

[0085] Examples of the dispersion medium include water such as natural water, purified water, distilled water, ion-exchanged water, and pure water; alcohol-based solvents such as methanol, ethanol, butanol, isobutanol, and n-propyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone diacetone alcohol; glycol ether-based solvents such as diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monobutyl ether; glycol ester-based solvents such as ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; ether-based solvents such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, and triethylene glycol dimethyl ether; Examples of suitable dispersion media include ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, propyl acetate, ethyl lactate, methyl lactate, and butyl lactate; hydrocarbon-based solvents such as toluene, xylene, solvent naphtha, hexane, cyclohexane, ethylcyclohexane, methylcyclohexane, heptane, octane, and decane; halogen-based solvents such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride; and the like. These dispersion media can be used either alone or in combination of two or more.

[0086] <Uses> The hollow particles of the present embodiment are useful as additives for master pellets for forming molded articles such as coating agents, paints, paper, information recording paper, light diffusion films (optical sheets), heat insulating films, thermoelectric conversion materials, light guide plate inks, anti-reflection films, light extraction films, photosensitive resin films, photosensitive resin compositions, light diffusion plates, and light guide plates; or additives for cosmetics.

[0087] <Coating Agent> Examples of the coating agent containing the hollow particles of this embodiment are given below.

[0088] In this aspect, the coating agent contains the hollow particles of this embodiment. The coating agent may further contain a binder in addition to the hollow particles of this embodiment.

[0089] The binder may be any known binder commonly used in this field, such as a thermosetting resin or a thermoplastic resin.

[0090] More specifically, examples of the binder include fluorine-based resins, polyamide resins, acrylic resins, polyurethane resins, acrylic urethane resins, butyral resins, etc. These binders can be used either alone or in combination of two or more.

[0091] The binder may be a homopolymer of one reactive monomer or a copolymer of multiple monomers.

[0092] Examples of reactive monomers used in the binder include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, (cyclo)hexyl (meth)acrylate, heptyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, iso-decyl (meth)acrylate, norbornyl (meth)acrylate, and isobutyl (meth)acrylate. monofunctional reactive monomers such as esters of (meth)acrylic acid with alcohols having 1 to 25 carbon atoms, such as bornyl (meth)acrylate, adamantyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, iso-stearyl (meth)acrylate, isobornyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and 2-ethylhexyl (meth)acrylate;Trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate (pentaerythritol triacrylate or pentaerythritol trimethacrylate), pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, di Polyfunctional reactive monomers such as pentaerythritol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate are also included.

[0093] When using these reactive monomers, a polymerization initiator that initiates a curing reaction by ionizing radiation may be used, such as imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, and thioxanthone derivatives.

[0094] Furthermore, inorganic binders such as hydrolysates of silicon alkoxides can also be used. Examples of silicon alkoxides include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, allyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxytrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyl. Examples of suitable alkylsilanes include propyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, and diethyldiethoxysilane.

[0095] A wide variety of known commercially available binders can be used. Examples of commercially available binders include "ALFON UC-3510" (average molecular weight 2000) manufactured by Toagosei Co., Ltd., "NK Ester A-TMM-3LM-N" manufactured by Shin-Nakamura Chemical Co., Ltd., and "DIANAL LR-102" and "DIANAL BR-106" manufactured by Mitsubishi Rayon Co., Ltd. These binders can be used alone or in combination of two or more.

[0096] In this embodiment, when the coating agent contains a binder and the hollow particles of this embodiment, the content of the hollow particles in the coating agent is adjusted appropriately depending on the application, but is usually 0.1 to 1,000 parts by mass per 100 parts by mass of the binder.

[0097] The coating agent usually contains a dispersion medium, which may be either an aqueous or oil-based medium.

[0098] Examples of the aqueous medium include water, alcohol-based solvents, and glycol ether-based solvents.

[0099] Examples of the oily medium include hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as dioxane and ethylene glycol diethyl ether, and glycol ester solvents such as ethylene glycol monoethyl ether acetate and propylene glycol monomethyl ether acetate.

[0100] In addition to the hollow particles of this embodiment, the coating agent may further contain additives such as a curing agent, a colorant, an antistatic agent, and a leveling agent.

[0101] The substrate to which the coating agent is applied is not particularly limited, and a substrate depending on the application can be used. For example, in optical applications, transparent substrates such as glass substrates and transparent resin substrates are used.

[0102] <Master Pellets> Examples of the master pellets containing the hollow particles of this embodiment are shown below.

[0103] In this embodiment, the master pellet contains the hollow particles of this embodiment. The master pellet may further contain a base resin in addition to the hollow particles of this embodiment.

[0104] The base resin may be a known thermoplastic resin commonly used in this field. Examples of the thermoplastic resin include (meth)acrylic resin, alkyl (meth)acrylate-styrene copolymer resin, polycarbonate resin, polyester resin, polyethylene resin, polypropylene resin, and polystyrene resin. These thermoplastic resins may be used alone or in combination of two or more.

[0105] The base resin is preferably at least one selected from the group consisting of (meth)acrylic resins, alkyl (meth)acrylate-styrene copolymer resins, polycarbonate resins, and polyester resins, in order to further improve transparency.

[0106] The base resin may contain small amounts of additives such as ultraviolet absorbers, heat stabilizers, colorants, and fillers.

[0107] In this embodiment, the master pellets can be produced by melt-kneading a base resin and the hollow particles of this embodiment, followed by a molding method such as extrusion molding or injection molding.

[0108] In this embodiment, the content of hollow particles in the master pellet is preferably 0.1 to 60% by mass, more preferably 0.3 to 30% by mass, and even more preferably 0.4 to 10% by mass.

[0109] In this embodiment, the master pellets are molded into a molded article by, for example, extrusion molding, injection molding, or press molding. A base resin may be newly added during molding.

[0110] The base resin is preferably added in such an amount that the content of hollow particles in the final molded product is 0.1 to 60% by mass.

[0111] During molding, small amounts of additives such as ultraviolet absorbers, heat stabilizers, colorants, and fillers may be added.

[0112] <Cosmetics> Examples of cosmetics containing the hollow particles of this embodiment are given below.

[0113] In this embodiment, the cosmetic contains the hollow particles of this embodiment. In this embodiment, examples of the cosmetic include solid cosmetics such as face powder and foundation, powder cosmetics such as baby powder and body powder, and liquid cosmetics such as lotion, emulsion, cream, liquid foundation, body lotion, and pre-shave lotion.

[0114] The content of hollow particles in a cosmetic varies depending on the type of cosmetic.

[0115] In the case of solid cosmetics such as face powder and foundation, the content of hollow particles in the cosmetics is preferably 1 to 20% by mass, more preferably 3 to 15% by mass.

[0116] In the case of powdery cosmetics such as baby powder and body powder, the content of hollow particles in the cosmetics is preferably 1 to 20% by mass, more preferably 3 to 15% by mass.

[0117] In the case of liquid cosmetics such as lotion, emulsion, cream, liquid foundation, body lotion, and pre-shave lotion, the content of hollow particles in the cosmetics is preferably 1 to 15% by mass, more preferably 3 to 10% by mass.

[0118] In this embodiment, other ingredients that can be added to the cosmetic include, for example, inorganic compounds such as mica and talc, coloring pigments such as iron oxide, titanium oxide, ultramarine, Prussian blue and carbon black, and synthetic dyes such as azo dyes, in order to improve optical functions and tactile feel.

[0119] When the cosmetic is a liquid cosmetic, the liquid medium is not particularly limited, but water, alcohol, hydrocarbon, silicone oil, vegetable or animal fats and oils, etc. may be used.

[0120] In this embodiment, various functions can be added to the cosmetic by adding, in addition to the other ingredients described above, moisturizing agents, anti-inflammatory agents, whitening agents, UV protection agents, disinfectants, antiperspirants, cooling agents, fragrances, and the like that are commonly used in cosmetics.

[0121] <Anti-Reflection Film> Examples of the anti-reflection film containing hollow particles according to this embodiment are described below.

[0122] In this embodiment, the anti-reflection film contains the hollow particles of the present embodiment. In this embodiment, examples of the anti-reflection film include a film and a sheet-like object.

[0123] In this embodiment, a film containing hollow particles or a sheet-like object containing hollow particles can be used as an anti-reflection film because the refractive index is reduced by the air layer present in the hollow portions of the hollow particles.

[0124] In this embodiment, the antireflection film can be obtained by applying the coating agent to a substrate by a well-known method such as a dipping method, a spraying method, a spin coating method, a spinner method, or a roll coating method, drying the coating, and, if necessary, further performing heating, ultraviolet irradiation, baking, or the like.

[0125] <Light Extraction Film> Examples of the light extraction film containing hollow particles according to this embodiment will be described below.

[0126] In this embodiment, the light extraction film contains the hollow particles of this embodiment. In LEDs, organic EL lighting, and the like, the difference in refractive index between the air layer and the light-emitting layer is large, so emitted light is easily trapped inside the element. For this reason, a light extraction film is used to improve light emission efficiency.

[0127] In this embodiment, the light extraction film may be, for example, a film, a sheet-like object, etc. A film containing hollow particles or a sheet-like object containing hollow particles can be used as the light extraction film because the refractive index is reduced by the air layer in the hollow portion of the hollow particles.

[0128] In this embodiment, the light extraction film can be obtained by applying the coating agent to a substrate by a well-known method such as a dipping method, a spraying method, a spin coating method, a spinner method, or a roll coating method, drying the coating, and, if necessary, further performing heating, ultraviolet irradiation, baking, or the like.

[0129] <Thermal Insulation Film> The following will exemplify aspects of the thermal insulation film containing hollow particles according to this embodiment.

[0130] In this aspect, the heat insulating film contains the hollow particles of this embodiment. Examples of the heat insulating film include a film and a sheet-like shape.

[0131] In this aspect, a film containing the hollow particles of this embodiment or a sheet-like object containing the hollow particles of this embodiment can be used as a heat insulating film because it has an air layer in the hollow spaces of the hollow particles. Furthermore, because the average particle diameter of the hollow particles is small, the heat insulating film has high transparency. Furthermore, because the binder is less likely to penetrate into the hollow spaces of the hollow particles, the heat insulating film has high heat insulating properties.

[0132] In this embodiment, the heat insulating film can be obtained by applying the coating agent to a substrate by a well-known method such as dipping, spraying, spin coating, spinner coating, or roll coating, drying the coating, and then, if necessary, heating, irradiating with ultraviolet light, baking, or the like.

[0133] <Low Dielectric Constant Film> Examples of the low dielectric constant film containing hollow particles according to this embodiment will be described below.

[0134] In this embodiment, the low dielectric constant film contains the hollow particles of this embodiment. Examples of the low dielectric constant film include a film and a sheet-like object.

[0135] In this embodiment, a film containing hollow particles or a sheet-like object containing hollow particles can be used as a low-dielectric-constant film because the hollow particles have an air layer in the hollow spaces thereof. Furthermore, because the average particle diameter of the hollow particles is small, the low-dielectric-constant film has high transparency.

[0136] In this embodiment, the low dielectric constant film can be obtained by applying the coating agent to a substrate by a well-known method such as a dipping method, a spraying method, a spin coating method, a spinner method, or a roll coating method, drying the coating, and further, if necessary, performing heating, ultraviolet irradiation, baking, or the like.

[0137] <Photosensitive Resin Composition> Examples of the photosensitive resin composition containing the hollow particles of this embodiment are described below.

[0138] In this aspect, the photosensitive resin composition contains the hollow particles of this embodiment. The photosensitive resin composition containing the hollow particles has a low refractive index because the hollow particles have an air layer in the hollow portion. Furthermore, the photosensitive resin composition has high transparency because the hollow particles have a small average particle diameter.

[0139] In this embodiment, the photosensitive resin composition can be obtained by applying the coating agent to a substrate by a well-known method such as a dipping method, a spraying method, a spin coating method, a spinner method, or a roll coating method, drying the coating agent, and, if necessary, further performing heating, ultraviolet irradiation, baking, or the like.

[0140] 2. Method for Producing Hollow Particles The hollow particles of this embodiment can usually be produced by surface-treating hollow particles in a hollow particle dispersion with a phosphate ester compound.

[0141] The method for producing hollow particles according to this embodiment will be described in detail below. Hereinafter, the step of surface-treating hollow particles with a phosphate ester compound may be simply referred to as the "surface treatment step."

[0142] In the surface treatment step, details of the phosphate ester compound are as described above in "1. Hollow particles" unless otherwise specified.

[0143] In the surface treatment step, the amount of the phosphate ester compound used is preferably 10 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the hollow particles.

[0144] The surface treatment step preferably involves the following steps (1), (2), (3), and (4) in this order: Step (1): Dissolve a phosphate ester compound in an organic solvent in a container. Step (2): Add a hollow particle dispersion and stir at room temperature to prepare a slurry. Step (3): Add the prepared slurry to an evaporator or the like, and remove the dispersion medium of the hollow particle dispersion and the organic solvent from step (1) from the slurry in a water bath or the like under reduced pressure. Step (4): Add an organic solvent and perform solvent substitution using an evaporator or the like to prepare a dispersion of hollow particles surface-treated with a phosphate ester compound.

[0145] In the above step (1), examples of the organic solvent include lower alcohols such as methanol, ethanol, 1-propanol (n-propyl alcohol), 2-propanol (isopropyl alcohol), 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol; hydrocarbon solvents such as toluene, xylene, hexane, and cyclohexane; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate, methyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate; ether solvents such as isopropyl ether and tetrahydrofuran; glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol; glycol solvents such as diethylene glycol monomethyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These organic solvents may be used alone or in combination of two or more.

[0146] In the above step (1), the phosphate ester compound is as described above in "1. Hollow particles."

[0147] In the above step (1), the amount of the organic solvent used is preferably 500 parts by mass or more and 4000 parts by mass or less, more preferably 1000 parts by mass or more and 3500 parts by mass or less, per 100 parts by mass of the phosphate ester compound.

[0148] The method for producing the hollow particle dispersion liquid used in the above step (2) will be described later in the section <Method for producing hollow particle dispersion liquid>.

[0149] In the above step (3), the temperature at which vacuum distillation is carried out is preferably 30°C or higher and 200°C or lower.

[0150] In the above step (4), the temperature at which the solvent substitution is carried out is preferably 30°C or higher and 200°C or lower.

[0151] In the above step (4), examples of the organic solvent include lower alcohols such as methanol, ethanol, 1-propanol (n-propyl alcohol), 2-propanol (isopropyl alcohol), 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol; hydrocarbon solvents such as toluene, xylene, hexane, and cyclohexane; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate, methyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate; ether solvents such as isopropyl ether and tetrahydrofuran; glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These organic solvents may be used alone or in combination of two or more.

[0152] <Method for Producing Hollow Particle Dispersion> The hollow particle dispersion can be produced, for example, through a step of preparing polymer particles containing a non-reactive solvent (polymerization step), a step of phase-separating the non-reactive solvent from the polymer particles (phase separation step), a step of removing the non-reactive solvent as needed (solvent removal step), and a step of dispersing the particles in a medium (dispersion step).

[0153] The method for producing a hollow particle dispersion may be a method in which a polymerization step and a phase separation step are carried out simultaneously by reacting a reactive monomer, or a method in which polymer particles are first formed before phase separation of a non-reactive solvent, and then phase separation occurs. The method in which polymer particles are first formed and then phase separation occurs is preferred because it can suppress the generation of pinholes and improve monodispersity.

[0154] In the method in which polymer particles are first formed before phase separation of the non-reactive solvent and then phase separation occurs, specifically, a reactive monomer having a (meth)acrylic reactive functional group and a non-(meth)acrylic reactive functional group is polymerized based on either of the two functional groups to produce polymer particles.

[0155] The non-reactive solvent is contained in the polymer particles by mixing it with the reactive monomer in advance or by allowing it to be absorbed into the polymer particles after preparation.

[0156] Next, the remaining functional group of the two functional groups is polymerized to separate the polymer from the non-reactive solvent, resulting in microcapsule particles encapsulating the non-reactive solvent.The non-reactive solvent is then removed to yield hollow particles.

[0157] As described above, by separating the polymerization step from the phase separation step, the following advantages are achieved: the gaps between the polymer shells that existed in conventional manufacturing methods are eliminated, thereby suppressing the occurrence of pinholes in the shells of the resulting hollow particles; and the shape of the microcapsule particles and hollow particles does not depend on the oil droplets, but on the shape and particle size distribution of the polymer particles before phase separation, making it easier to obtain microcapsule particles and hollow particles with high monodispersity. The manufacturing method will be described below.

[0158] (A) Polymerization Step In the polymerization step, a reactive monomer having a (meth)acrylic reactive functional group and a non-(meth)acrylic reactive functional group is polymerized based on either one of the functional groups to produce polymer particles. The non-reactive solvent is incorporated into the polymer particles by mixing it with the reactive monomer in advance or by allowing it to be absorbed after the polymer particles are produced.

[0159] (a) Method for Producing Polymer Particles As a method for producing polymer particles, any method can be adopted from known methods such as bulk polymerization, solution polymerization, dispersion polymerization, suspension polymerization, emulsion polymerization, etc. Among them, suspension polymerization or emulsion polymerization, which can produce polymer particles relatively easily, is preferred. Furthermore, emulsion polymerization, which can easily produce polymer particles with high monodispersity, is more preferred.

[0160] <Polymerization initiator> When polymerizing, it is preferable to add a compound for reacting the functional group to be polymerized. When polymerizing a (meth)acrylic reactive functional group, a polymerization initiator can be used as this compound.

[0161] Examples of the polymerization initiator include persulfates such as ammonium persulfate (ammonium peroxodisulfate), potassium persulfate, and sodium persulfate; organic peroxides such as cumene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, dimethylbis(tert-butylperoxy)hexane, dimethylbis(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, bis(tert-butylperoxy)trimethylcyclohexane, butyl-bis(tert-butylperoxy)valerate, tert-butyl 2-ethylhexaneperoxyate, dibenzoyl peroxide, paramenthane hydroperoxide, and tert-butyl peroxybenzoate;2,2-Azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate, 2,2-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis(1-imino-1-pyrrolidone) dihydrochloride, 2,2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 4,4-azobis(4-cyanopentanoic acid), 2,2-azobisisobutyronitrile (2,2-azobis(2-methyl-butyronitrile), 2,2-azobis(2-isopropylbutyronitrile), 2,2-azobis(2,3-dimethylbutyronitrile), 2,2-azobis(2,4-dimethylbutyronitrile), nitrile), 2,2-azobis(2-methylcapronitrile), 2,2-azobis(2,3,3-trimethylbutyronitrile), 2,2-azobis(2,4,4-trimethylvaleronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2,4-dimethyl-4-ethoxyvaleronitrile), 2,2-azobis(2,4-dimethyl-4-n-butoxyvaleronitrile), 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis[N-(2-propenyl)-2-methylpropionamide ], azo compounds such as 2,2-azobis(N-butyl-2-methylpropionamide), 2,2-azobis(N-cyclohexyl-2-methylpropionamide), 1,1-azobis(1-acetoxy-1-phenylethane), 1,1-azobis(cyclohexane-1-carbonitrile), dimethyl-2,2-azobis(2-methylpropionate), dimethyl-2,2-azobisisobutyrate, dimethyl-2,2'-azobis(2-methylpropionate), 2-(carbamoylazo)isobutyronitrile, and 4,4-azobis(4-cyanovaleric acid);These polymerization initiators can be used alone or in combination of two or more.

[0162] Alternatively, a redox initiator may be used as the polymerization initiator, which is a combination of the above-mentioned persulfate and organic peroxide polymerization initiator with a reducing agent such as sodium sulfoxylate formaldehyde, sodium hydrogen sulfite, ammonium hydrogen sulfite, sodium thiosulfate, ammonium thiosulfate, hydrogen peroxide, sodium hydroxymethanesulfinate, L-ascorbic acid and its salts, cuprous salts, or ferrous salts.

[0163] In the case of emulsion polymerization, the polymerization initiator is preferably a water-soluble polymerization initiator capable of emulsion polymerization in a water solvent.

[0164] Examples of the water-soluble polymerization initiator include persulfates such as ammonium persulfate (ammonium peroxodisulfate), potassium persulfate, and sodium persulfate; 2,2-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane]disulfate dihydrate, 2,2-azobis(2-amidinopropane)dihydrochloride, 2,2-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, and 2,2-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride. azo compounds such as 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis(1-imino-1-pyrrolidino-2-ethylpropane) dihydrochloride, 2,2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and 4,4-azobis(4-cyanopentanoic acid). These water-soluble polymerization initiators can be used either alone or in combination of two or more.

[0165] The polymer particles are preferably polymerized first based on the (meth)acrylic reactive functional groups, so that the polymer particles have unreacted non-(meth)acrylic reactive functional groups. If the polymer is polymerized first based on the non-(meth)acrylic reactive functional groups, the polymer particles may be less likely to absorb non-reactive solvents.

[0166] <Chain Transfer Agent> A chain transfer agent may be used during polymerization of the reactive monomer. Examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, tert-octyl mercaptan, n-dodecyl mercaptan, and tert-dodecyl mercaptan; phenolic compounds such as α-methylstyrene dimer, 2,6-di-tert-butyl-4-methylphenol, and styrenated phenol; allyl compounds such as allyl alcohol; and halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, and carbon tetrachloride. These chain transfer agents can be used alone or in combination of two or more. The upper limit of the amount of chain transfer agent used is usually 10 parts by mass per 100 parts by mass of the reactive monomer.

[0167] <Surfactant> A surfactant may be used during polymerization of the reactive monomer. The type of surfactant is not particularly limited, and for example, a wide variety of known surfactants can be used.

[0168] Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. These surfactants can be used alone or in combination of two or more. Among these surfactants, anionic surfactants are preferred.

[0169] The upper limit of the amount of surfactant used is usually 5 parts by mass per 100 parts by mass of the reactive monomer.

[0170] A wide variety of commercially available anionic surfactants can be used, including, for example, "Aqualon AR-1025" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0171] <Dispersion Aid> When preparing polymer particles, a hydrophilic monomer may be used as a reactive monomer other than the (meth)acrylic reactive monomer. The hydrophilic monomer serves as a dispersing aid, and therefore, by using the hydrophilic monomer, the dispersion stability during polymerization can be further improved.

[0172] The type of the hydrophilic monomer is not particularly limited, and for example, a wide variety of known hydrophilic monomers can be used. Examples of the hydrophilic monomer include carboxyl group-containing vinyl monomers and their salts; sulfonic group-containing vinyl monomers and vinyl sulfate monoesters, and their salts; phosphoric acid group-containing vinyl monomers and their salts; hydroxyl group-containing vinyl monomers; and nitrogen-containing vinyl monomers. These hydrophilic monomers can be used alone or in combination of two or more.

[0173] Examples of carboxyl group-containing vinyl monomers include (anhydride) maleic acid, maleic acid monoalkyl esters, fumaric acid, fumaric acid monoalkyl esters, crotonic acid, itaconic acid, itaconic acid monoalkyl esters, itaconic acid glycol monoethers, citraconic acid, citraconic acid monoalkyl esters, cinnamic acid, and salts thereof. Examples of these salts include alkali metal salts (sodium salts, potassium salts, etc.), ammonium salts, amine salts, and quaternary ammonium salts of the carboxyl group-containing vinyl monomers. The carboxyl group-containing vinyl monomers and their salts can be used alone or in combination of two or more.

[0174] Examples of sulfonic acid group-containing vinyl monomers and vinyl sulfate monoesters include vinyl sulfonic acid, (meth)allylsulfonic acid, p-styrenesulfonic acid, sulfopropyl(meth)acrylate, 2-hydroxy-3-(meth)acryloxypropylsulfonic acid, 2-(meth)acryloylamino-2,2-dimethylethanesulfonic acid, 2-(meth)acryloyloxyethanesulfonic acid, and 3-(meth)acryloyloxy-2-hydroxypropanesulfone. Examples of suitable salts include sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, 3-(meth)acrylamido-2-hydroxypropanesulfonic acid, alkyl (carbon number 3 to 18)allylsulfosuccinic acid, sulfate esters of poly(n = 2 to 30)oxyalkylene (ethylene, propylene, butylene, etc.; may be mono, random, or block) mono(meth)acrylates [e.g., poly(n = 5 to 15)oxypropylene monomethacrylate sulfate ester], and salts thereof. Examples of such salts include alkali metal salts (sodium salt, potassium salt, etc.), ammonium salts, amine salts, and quaternary ammonium salts of the sulfonic acid-containing vinyl monomers and vinyl sulfate monoesters. The sulfonic acid-containing vinyl monomers and vinyl sulfate monoesters, and salts thereof, may be used alone or in combination of two or more.

[0175] Among the above sulfonic acid group-containing vinyl monomers and vinyl sulfate monoesters, and salts thereof, sodium p-styrenesulfonate is preferred from the viewpoint of further enhancing dispersion stability during polymerization.

[0176] Examples of phosphoric acid group-containing vinyl monomers include 2-hydroxyethyl(meth)acryloyl phosphate, phenyl-2-acryloyloxyethyl phosphate, and salts thereof. Examples of these salts include alkali metal salts (sodium salts, potassium salts, etc.), ammonium salts, amine salts, and quaternary ammonium salts of the phosphoric acid group-containing vinyl monomers. The phosphoric acid group-containing vinyl monomers and salts thereof can be used alone or in combination of two or more.

[0177] Examples of hydroxyl group-containing vinyl monomers include hydroxystyrene, N-methylol(meth)acrylamide, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, (meth)allyl alcohol, etc. The above hydroxyl group-containing vinyl monomers can be used either alone or in combination of two or more.

[0178] Examples of nitrogen-containing vinyl monomers include quaternized products of tertiary amine group-containing vinyl monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acrylamide, N-methyl(meth)acrylamide, N-butylacrylamide, diacetone acrylamide, (meth)acrylonitrile, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylamide (which are quaternized using a quaternizing agent such as methyl chloride, dimethyl sulfate, benzyl chloride, or dimethyl carbonate).

[0179] (b) Absorption of Non-reactive Solvent Absorption of the non-reactive solvent into the polymer particles can be carried out during or after the preparation of the polymer particles. Furthermore, absorption of the non-reactive solvent can be carried out in the presence or absence of a dispersion medium that is incompatible with the non-reactive solvent. Absorption in the presence of a dispersion medium is preferred because absorption of the non-reactive solvent can be carried out efficiently. When a medium is used in the method for producing polymer particles, the medium may be used as the dispersion medium as is, or the polymer particles may be isolated from the medium and then dispersed in another dispersion medium.

[0180] A non-reactive solvent that is incompatible with the dispersion medium is added to the dispersion medium containing the polymer particles, and the non-reactive solvent can be absorbed into the polymer particles by stirring or the like for a certain period of time.

[0181] The absorption of the non-reactive solvent during the production of the polymer particles can be achieved by selecting a dispersion medium and a non-reactive solvent appropriate for the production of the polymer particles. For example, when producing polymer particles by emulsion polymerization in an aqueous solvent, a non-reactive solvent that is incompatible with water can be added to the aqueous solvent in advance, and then a reactive monomer can be polymerized, thereby simultaneously producing the polymer particles and absorbing the polymer particles. By simultaneously producing the polymer particles and absorbing the polymer particles, the time required for absorbing the non-reactive solvent can be reduced.

[0182] <Dispersion Medium> The dispersion medium is not particularly limited as long as it is a liquid that does not completely dissolve the polymer particles. Examples of the dispersion medium include water such as natural water, purified water, distilled water, ion-exchanged water, and pure water; alcohol-based solvents such as methanol, ethanol, butanol, isobutanol, and n-propyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone diacetone alcohol; ether-based solvents such as ethylene glycol mono-n-propyl ether, diethylene glycol mono-n-propyl ether, and propylene glycol monomethyl ether; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, propyl acetate, ethyl lactate, methyl lactate, and butyl lactate; hydrocarbon-based solvents such as toluene, xylene, solvent naphtha, hexane, cyclohexane, ethylcyclohexane, methylcyclohexane, heptane, octane, and decane; and halogen-based solvents such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride. These dispersion media can be used alone or in combination of two or more.

[0183] <Non-reactive solvent> The non-reactive solvent is not particularly limited as long as it is a liquid substance that is incompatible with the dispersion medium. In this case, "incompatible with the dispersion medium" means that the solubility of the non-reactive solvent in the dispersion medium (at 25°C) is 10% by weight or less.

[0184] For example, when ion-exchanged water is used as the dispersion medium, examples of usable non-reactive solvents include butane, pentane, hexane, cyclohexane, heptane, decane, hexadecane, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, 1,4-dioxane, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, etc. These non-reactive solvents can be used either alone or in combination of two or more.

[0185] The amount of non-reactive solvent added is not particularly limited, but is 20 to 5,000 parts by mass relative to 100 parts by mass of polymer particles. If it is less than 20 parts by mass, the hollow portion of the obtained microcapsule particles or hollow particles may become small, and the desired properties may not be obtained. If it exceeds 5,000 parts by mass, the hollow portion may become too large, and the strength of the obtained microcapsule particles or hollow particles may decrease.

[0186] (B) Phase Separation Step After the polymerization step, the remaining reactive functional groups are polymerized to cause phase separation between the polymer and the non-reactive solvent. By the phase separation, microcapsule particles encapsulating the non-reactive solvent are obtained.

[0187] In this specification, the term "hollow" in hollow particles is not limited to particles in which air is present in the hollow portion, but also includes particles in which a gas other than air is present in the hollow portion.

[0188] Furthermore, in this specification, hollow particles are not limited to hollow particles in which a gas exists in the hollow portion, but also include microcapsule particles in which a non-reactive solvent or other dispersion medium exists in the hollow portion.

[0189] The compound added to polymerize the remaining reactive functional groups can be the same as the polymerization initiator for polymerizing the (meth)acrylic reactive functional groups and the crosslinking agent (crosslinkable monomer) for polymerizing the non-(meth)acrylic reactive functional groups described in the polymerization step above.

[0190] (C) Solvent Removal (Solvent Replacement) Step If necessary, the non-reactive solvent encapsulated in the microcapsule particles can be removed or replaced to obtain hollow particles in which gas such as air and other solvents are present in the hollow portion.

[0191] The method for removing the non-reactive solvent is not particularly limited, and examples thereof include vacuum distillation. The conditions for vacuum distillation are not particularly limited and can be appropriately selected depending on the type of non-reactive solvent, etc. The pressure when performing vacuum distillation is, for example, 500 Pa or less. The temperature when performing vacuum distillation is, for example, 30°C or more and 200°C or less. The time when performing vacuum distillation is, for example, 30 minutes or more and 50 hours or less.

[0192] Alternatively, the non-reactive solvent can be replaced by a solvent substitution operation. Examples of this operation include adding an appropriate dispersion medium to microcapsule particles encapsulating the non-reactive solvent or a dispersion thereof, and then performing stirring or the like to replace the non-reactive solvent inside the particles with the dispersion medium, followed by removing the excess non-reactive solvent and dispersion medium by vacuum distillation, centrifugation, ultrafiltration, or the like. The solvent substitution operation may be performed once or multiple times. Among these, vacuum distillation is preferred because it can promote the esterification reaction. It is more preferred to perform heating during vacuum distillation.

[0193] (D) Dispersion Step The hollow particle dispersion may be, for example, a microcapsule particle dispersion encapsulating the non-reactive solvent obtained after the phase separation step, or a dispersion in which the non-reactive solvent has been replaced with another solvent. When replacing the non-reactive solvent with another solvent, the solvent present after the phase separation step is once removed to extract the hollow particles, and the extracted hollow particles can be dispersed in a desired dispersion medium.

[0194] Examples of the dispersion medium include water such as natural water, purified water, distilled water, ion-exchanged water, and pure water; alcohol-based solvents such as methanol, ethanol, butanol, isobutanol, and n-propyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone diacetone alcohol; ether-based solvents such as ethylene glycol mono-n-propyl ether, diethylene glycol mono-n-propyl ether, and propylene glycol monomethyl ether; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, propyl acetate, ethyl lactate, methyl lactate, and butyl lactate; hydrocarbon-based solvents such as toluene, xylene, solvent naphtha, hexane, cyclohexane, ethylcyclohexane, methylcyclohexane, heptane, octane, and decane; halogen-based solvents such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride; and the like. These dispersion media can be used alone or in combination of two or more.

[0195] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. In the following examples and comparative examples, "room temperature" means a temperature within the range of 20°C to 25°C.

[0196] First, the measurement methods and evaluation methods in the Examples section will be described. Hereinafter, the hollow particle propylene glycol monomethyl ether acetate dispersions obtained in Examples 1 to 3 will also be referred to as "hollow particle dispersions obtained in the Examples," and the hollow particle alcohol-based dispersions obtained in Comparative Examples 1 and 2 will also be referred to as "hollow particle dispersions obtained in the Comparative Examples." Furthermore, the hollow particle propylene glycol monomethyl ether acetate dispersions obtained in Examples 1 to 3 and the hollow particle alcohol-based dispersions obtained in Comparative Examples 1 and 2 will also be collectively referred to as "hollow particle dispersions obtained in the Examples and Comparative Examples."

[0197] <Average particle size of hollow particles contained in hollow particle aqueous dispersion> The average particle size of hollow particles contained in hollow particle aqueous dispersion was measured by the following method.

[0198] Specifically, the hollow particle aqueous dispersion A (solid content concentration = 10 mass%) prepared in Production Example 1 was further diluted with ion-exchanged water to prepare a hollow particle aqueous dispersion having a solid content concentration of 0.3 mass%.

[0199] The Z-average particle size of the prepared hollow particle aqueous dispersion (solid content = 0.3% by mass) was measured using a particle size measuring device ("VASCOγ" manufactured by Cordouan Technologies) under the following conditions. The Z-average particle size was taken as the average particle size of the hollow particles contained in the hollow particle aqueous dispersion (solid content = 0.3% by mass). (Conditions of the particle size measuring device) Measurement temperature: 25°C Optical path length: 100 μm Measurement time: 60 seconds Number of accumulations: 3 Analysis method: Cumulant

[0200] <Average particle size of hollow particles contained in hollow particle propylene glycol monomethyl ether acetate dispersion> The average particle size of hollow particles contained in hollow particle propylene glycol monomethyl ether acetate dispersion was measured by the following method.

[0201] Specifically, the hollow particle dispersions obtained in the examples and comparative examples were further diluted with propylene glycol monomethyl ether acetate to prepare hollow particle propylene glycol monomethyl ether acetate dispersions having a solid content of 0.3 mass %.

[0202] Using a particle size measuring device ("VASCOγ" manufactured by Cordouan Technologies), the Z-average particle size of the prepared hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3% by mass) was measured under the following conditions. The Z-average particle size was taken as the average particle size of the hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3% by mass). (Conditions of the particle size measuring device) Measurement temperature: 25°C Optical path length: 100 μm Measurement time: 60 seconds Number of accumulations: 3 Analysis method: cumulant

[0203] <Binder Hollowness> The volume fraction of air in hollow particles contained in the binder (binder hollowness) (volume %) was measured by the following method.

[0204] Specifically, 0.5 parts by mass of the hollow particle dispersion obtained in the Examples or 0.5 parts by mass of the hollow particle dispersion obtained in the Comparative Examples, 0.95 parts by mass of a liquid carboxyl group-containing acrylic resin ("ALFON UC-3510" manufactured by Toa Gosei Co., Ltd., average molecular weight 2000) as a binder, and 0.5 parts by mass of methanol were each accurately weighed and placed in a glass bottle, and the mixture was uniformly mixed using an ultrasonic cleaner to obtain a hollow particle dispersion.

[0205] Next, the obtained hollow particle dispersion liquid was dried in a vacuum dryer at 90° C. for 16 hours to volatilize and completely remove the organic solvent contained in the system, thereby obtaining a binder containing hollow particles.

[0206] The obtained binder containing hollow particles was stored for 30 minutes in a constant temperature and humidity environment set at 23°C and 55% humidity, and then the refractive index of the binder and the refractive index of the shells of the hollow particles contained in the binder (hereinafter referred to as "refractive index of the shells of hollow particles") were measured using an Abbe refractometer ("NAR-1T SOLID" manufactured by Atago Co., Ltd.) The refractive index of the binder was 1.468, and the refractive index of the shells of the hollow particles contained in the binder was 1.537.

[0207] The refractive index of air is 1.00 and the density of air is 0 (g / cm ３ ), the refractive index of the shell of the hollow particles contained in the binder is 1.537, and the density of the shell of the hollow particles is 1.27 (g / cm ３ ), the refractive index of the binder is 1.468 and the density of the binder is 1.05 (g / cm ３ ), the air volume fraction q (=binder hollowness) (volume %) of the hollow particles contained in the binder was calculated by solving the following Maxwell-Garnett equation. Note that the "shell density of hollow particles" refers to the "shell density" shown in Table 2 below. Maxwell-Garnett equation: (Na ２ -Nm ２ ) / (Na ２ +2Nm ２ ) = q(Np ２ -Nm ２ ) / (Np ２ +2Nm ２ )

[0208] <Proportion of Phosphate Ester Compound After Solvent Washing> The hollow particle dispersions obtained in the Examples and Comparative Examples were subjected to solvent washing three times, and the content of the phosphate ester compound adhered to the outer surfaces of the shells of the hollow particles contained in the hollow particle dispersions obtained in the Examples and Comparative Examples [(mass of phosphate ester compound / (total mass of phosphate ester compound and hollow particles))×100] (mass %) was measured.

[0209] Specifically, 5 parts by mass of the hollow particle dispersion obtained in each Example or 10 parts by mass of the hollow particle dispersion obtained in each Comparative Example was weighed into a conical tube for a centrifuge and centrifuged at a centrifugal acceleration of 42,200 G using a centrifuge ("CR22N" manufactured by Eppendorf-Himac Technologies). The supernatant was removed from the conical tube. Next, to wash the hollow particles with a solvent, 10 g of propylene glycol monomethyl ether acetate was added as a solvent to redisperse the hollow particles, followed by another centrifugation and the supernatant was removed from the conical tube. This solvent washing of the hollow particles with propylene glycol monomethyl ether acetate was performed a total of three times, and then the hollow particles were dried in a vacuum dryer (manufactured by Tokyo Rikakikai Co., Ltd., product name "VOS-310C") at a pressure of -0.1 MPa and 90°C for 3 hours to obtain a dry powder.

[0210] The obtained dry powder was subjected to infrared spectroscopy analysis (ATR-FTIR) under the following conditions to obtain an infrared absorption spectrum. The ratio of the absorbance (A1350) to the absorbance (A1385) of the obtained infrared absorption spectrum (absorbance ratio: A1350 / A1385) was calculated, and the proportion of phosphate ester compound after solvent washing was measured using the calibration curve described below. The measured proportion of phosphate ester compound was defined as the content of phosphate ester compound attached to the outer surface of the shell of hollow particles contained in the hollow particle dispersions obtained in the Examples and Comparative Examples [(mass of phosphate ester compound / (total mass of phosphate ester compound and hollow particles)) × 100] (mass %).

[0211] The absorbance (A1350) and absorbance (A1385) were measured using a measuring device sold by Thermo Fisher Scientific under the product name "Nicolet iS5" connected to an ATR accessory "iD5" manufactured by Thermo Fisher Scientific.

[0212] (ATR-FTIR measurement conditions) High refractive index crystal seed: Diamond with ZnSe lens Incident angle: 42°±1° Measurement area: 600cm －１ ~4000cm －１ Wavenumber dependence of measurement depth: Uncorrected Number of reflections: 1 Detector: DTGS KBr Resolution: 4 cm －１ Number of measurements: 16 Other: In the ATR method, which normally uses an infrared absorption spectrum measured without contact with the sample as a background and performs processing that does not affect the measured spectrum, the intensity of the infrared absorption spectrum obtained by measurement varies depending on the degree of contact between the sample and the high refractive index crystal. Therefore, measurements were performed by applying the maximum load that can be applied with the ATR accessory to make the degree of contact approximately uniform.

[0213] The infrared absorption spectrum obtained under the above measurement conditions was subjected to peak processing as follows to determine the absorbance (A1350) and absorbance (A1385). Absorbance (A1350): 1325 cm of the infrared absorption spectrum. －１ From 1345cm －１ and the minimum absorbance between 1395 cm －１ From 1435 cm －１ The line connecting the lowest absorbance between －１ absorbance of 1355 cm －１ The maximum absorbance between 1325 cm and 1350 cm was determined as the absorbance (A1350). －１ From 1345cm －１ and the minimum absorbance between 1395 cm －１ From 1435 cm －１ The line connecting the lowest absorbance between －１absorbance of 1390 cm －１ The maximum absorbance between these values ​​was taken as the absorbance (A1385).

[0214] The calibration curve was obtained by adding polyoxyethylene alkyl ether phosphate ("Phosphanol RS-710" manufactured by Toho Chemical Industry Co., Ltd.) equivalent to 10 mass%, 20 mass%, 30 mass%, 40 mass%, and 50 mass% of the solid content of the hollow particle aqueous dispersion A to the hollow particle aqueous dispersion A (solid content concentration = 10 mass%) prepared in Production Example 1 and n-propyl alcohol in an amount equal to that of the hollow particle aqueous dispersion A to a container, stirring thoroughly, and then drying the mixture at 90°C for 3 hours under a pressure of -0.1 MPa using a vacuum dryer (product name "VOS-310C" manufactured by Tokyo Rikakikai Co., Ltd.) to obtain a dry powder. Using the method described above, the ratio of absorbance (A1350) to absorbance (A1385) (absorbance ratio: A1350 / A1385) was calculated, and a calibration curve was obtained by fitting the amount of polyoxyethylene alkyl ether phosphate added and the absorbance ratio (A1350 / A1385) with a quadratic function.

[0215] <Absorbance Ratio η (A1100 / A1720)> Five parts by mass of the hollow particle dispersion obtained in each Example or 10 parts by mass of the hollow particle dispersion obtained in each Comparative Example was weighed into a conical tube for a centrifuge and centrifuged at a centrifugal acceleration of 42,200 G using a centrifuge ("CR22N" manufactured by Eppendorf-Himac Technologies). The supernatant was then removed from the conical tube. Next, to wash the hollow particles with a solvent, 10 g of propylene glycol monomethyl ether acetate was added as a solvent to redisperse the hollow particles, followed by another centrifugation, and the supernatant was removed from the conical tube. This solvent washing of the hollow particles with propylene glycol monomethyl ether acetate was performed a total of three times, and then the hollow particles were dried in a vacuum dryer (manufactured by Tokyo Rikakikai Co., Ltd., product name "VOS-310C") at a pressure of -0.1 MPa and 90°C for 3 hours to obtain a dry powder.

[0216] The obtained dry powder was subjected to infrared spectroscopy analysis ATR (ATR-FTIR) measurement under the following conditions to obtain an infrared absorption spectrum. The ratio of the absorbance (A1100) to the absorbance (A1720) of the obtained infrared absorption spectrum (absorbance ratio η: A1100 / A1720) was calculated.

[0217] The absorbance (A1100) and absorbance (A1720) were measured using a measuring device sold by Thermo Fisher Scientific under the product name "Nicolet iS5" connected to an ATR accessory "iD5" manufactured by Thermo Fisher Scientific.

[0218] (ATR-FTIR measurement conditions) High refractive index crystal seed: Diamond with ZnSe lens Incident angle: 42°±1° Measurement area: 600cm －１ ~4000cm －１ Wavenumber dependence of measurement depth: Uncorrected Number of reflections: 1 Detector: DTGS KBr Resolution: 4 cm －１ Number of measurements: 16 Other: In the ATR method, which normally uses an infrared absorption spectrum measured without contact with the sample as a background and performs processing that does not affect the measured spectrum, the intensity of the infrared absorption spectrum obtained by measurement varies depending on the degree of contact between the sample and the high refractive index crystal. Therefore, measurements were performed by applying the maximum load that can be applied with the ATR accessory to make the degree of contact approximately uniform.

[0219] The infrared absorption spectrum obtained under the above measurement conditions was subjected to peak processing as follows to determine the absorbance (A1100) and absorbance (A1720). Absorbance (A1100): 1005 cm of the infrared absorption spectrum －１ From 1025 cm －１ and the minimum absorbance between 1200 cm －１ From 1215 cm －１ The line connecting the lowest absorbance between －１ Absorbance 1130 cm －１The maximum absorbance between 1550 cm and 1550 cm of the infrared absorption spectrum was determined as the absorbance (A1100). －１ From 1815 cm －１ The straight line connecting the sections near the absorbance of 1700 cm is used as the baseline. －１ Absorbance from 1740 cm －１ The maximum absorbance between these values ​​was taken as the absorbance (A1720).

[0220] The absorbance (A1100) obtained from the infrared absorption spectrum is the absorbance corresponding to the absorption spectrum resulting from the C--O stretching vibration of the ether or the C--O stretching vibration of the ester contained in the hollow particles.

[0221] The absorbance (A1720) obtained from the infrared absorption spectrum is the absorbance corresponding to the absorption spectrum derived from the C═O stretching vibration of the carbonyl group contained in the hollow particles.

[0222] (Production Example 1) Production of hollow particle aqueous dispersion A (solid content concentration = 10 mass%) In a 5 L stainless steel beaker, 3,600 parts by mass of ion-exchanged water, 1.6 parts by mass of an anionic surfactant (trade name "Aqualon AR-1025" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 8.0 parts by mass of sodium p-styrenesulfonate, and 8.0 parts by mass of ammonium peroxodisulfate were added and dissolved.

[0223] A mixed solution of 172 parts by mass of glycidyl methacrylate, 28 parts by mass of 3-methacryloxypropyltriethoxysilane, 4.0 parts by mass of n-octyl mercaptan, and 200 parts by mass of toluene was further added to the stainless steel beaker, and the mixture was stirred at room temperature for 10 minutes using an ultrasonic homogenizer (manufactured by Branson, Model SONIFIER 450) to prepare an emulsion.

[0224] The prepared emulsion was placed in a 5 L reactor equipped with a stirrer and a thermometer, and after replacing the inside with nitrogen to create a nitrogen atmosphere, the temperature was raised to 70° C. and a polymerization reaction was carried out for 2 hours with stirring at 70° C. Next, 100 parts by mass of ethylenediamine was added, and the temperature was raised to 80° C. under a nitrogen atmosphere, and then a reaction was carried out for 16 hours at 80° C. with stirring to obtain a hollow particle dispersion.

[0225] 4,000 parts by mass of the obtained hollow particle dispersion was cross-flow washed with 20,000 parts by mass of ion-exchanged water using a ceramic filter having a pore size of 50 nm, and the mixture was appropriately concentrated and ion-exchanged water was added thereto so that the solid content concentration became 10% by mass, thereby obtaining a hollow particle aqueous dispersion A (solid content concentration=10% by mass).

[0226] The hollow particles contained in the obtained hollow particle aqueous dispersion A (solid content = 10% by mass) had an average particle diameter of 80.1 nm.

[0227] The composition and physical properties of Production Example 1 are shown in Table 1.

[0228] Example 1 To a 10 L stainless steel beaker, 120 parts by mass of polyoxyethylene alkyl ether phosphate (Phosphanol RS-710 manufactured by Toho Chemical Industry Co., Ltd.) as a phosphate ester compound was added, and the mixture was dissolved with 1000 parts by mass of n-propyl alcohol, 600 parts by mass of propylene glycol monomethyl ether, and 2000 parts by mass of propylene glycol monomethyl ether acetate.

[0229] Further, 2000 parts by mass of the hollow particle aqueous dispersion A (solid content = 10% by mass) obtained in Production Example 1 was added, and the mixture was stirred at room temperature for 15 minutes using an ultrasonic homogenizer to prepare a hollow particle dispersion.

[0230] 2000 parts by mass of the prepared hollow particle dispersion was placed in a rotary evaporator equipped with a 4 L eggplant-shaped flask, and the ion-exchanged water, n-propyl alcohol, and propylene glycol monomethyl ether were distilled off under reduced pressure at a degree of vacuum of 200 hPa in a water bath at 70° C. During the distillation under reduced pressure, the remaining hollow particle dispersion was appropriately supplied so that the hollow particle dispersion in the 4 L eggplant-shaped flask became 2000 parts by mass.

[0231] Next, in a water bath at a temperature of 70°C and under a vacuum degree of 35 hPa, 2000 parts by mass of propylene glycol monomethyl ether acetate was appropriately supplied so that the hollow particle dispersion in the 4 L eggplant-shaped flask became 2000 parts by mass, and solvent substitution was performed using a rotary evaporator.

[0232] After the solvent exchange was completed, the mixture was cooled to room temperature to obtain a hollow particle propylene glycol monomethyl ether acetate dispersion. During the solvent exchange, the temperature was maintained at 70° C., and the degree of vacuum was adjusted from 200 hPa to 35 hPa as appropriate.

[0233] The hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3 mass%) had an average particle diameter of 87.9 nm. The hollow particles contained in the obtained hollow particle propylene glycol monomethyl ether acetate dispersion had a shell density of 1.27 g / cm ３ The binder had a hollow fraction of 35.6% by volume and an absorbance ratio η (A1100 / A1720) of 0.872. The proportion of the phosphate ester compound after solvent washing (the content of the phosphate ester compound adhered to the outer surfaces of the shells of the hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion obtained in Example 1) was 25.4% by mass.

[0234] Example 2 To a 10 L stainless steel beaker, 120 parts by mass of polyoxyethylene alkyl ether phosphate (Phosphanol RS-710 manufactured by Toho Chemical Industry Co., Ltd.) as a phosphate ester compound was added, and the mixture was dissolved with 3,000 parts by mass of n-propyl alcohol and 2,000 parts by mass of propylene glycol monomethyl ether acetate.

[0235] Further, 2000 parts by mass of the hollow particle aqueous dispersion A (solid content = 10% by mass) obtained in Production Example 1 was added, and the mixture was stirred at room temperature for 15 minutes using an ultrasonic homogenizer to prepare a hollow particle dispersion.

[0236] 2000 parts by mass of the prepared hollow particle dispersion was placed in a rotary evaporator equipped with a 4 L eggplant-shaped flask, and the ion-exchanged water and n-propyl alcohol were distilled off under reduced pressure at a degree of vacuum of 200 hPa in a water bath at 70° C. During the distillation under reduced pressure, the remaining hollow particle dispersion was appropriately supplied so that the hollow particle dispersion in the 4 L eggplant-shaped flask became 2000 parts by mass.

[0237] Next, in a water bath at a temperature of 70°C and under a vacuum degree of 35 hPa, 2000 parts by mass of propylene glycol monomethyl ether acetate was appropriately supplied so that the hollow particle dispersion in the 4 L eggplant-shaped flask became 2000 parts by mass, and solvent substitution was performed using a rotary evaporator.

[0238] After the solvent exchange was completed, the mixture was cooled to room temperature to obtain a hollow particle propylene glycol monomethyl ether acetate dispersion. During the solvent exchange, the temperature was maintained at 70° C., and the degree of vacuum was adjusted from 200 hPa to 35 hPa as appropriate.

[0239] The hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content = 0.3 mass%) had an average particle diameter of 80.8 nm. The hollow particles contained in the obtained hollow particle propylene glycol monomethyl ether acetate dispersion had a shell density of 1.27 g / cm. ３ The binder had a hollow fraction of 34.6% by volume and an absorbance ratio η (A1100 / A1720) of 0.882. The proportion of the phosphate ester compound after solvent washing (the content of the phosphate ester compound attached to the outer surfaces of the shells of the hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion obtained in Example 2) was 25.5% by mass.

[0240] (Example 3) A hollow particle propylene glycol monomethyl ether acetate dispersion was obtained in the same manner as in Example 2, except that the amount of polyoxyethylene alkyl ether phosphate (Phosphanol RS-710 manufactured by Toho Chemical Industry Co., Ltd.) used as the phosphate ester compound was changed from 120 parts by mass to 80 parts by mass. The above was added and dissolved in 3,000 parts by mass of n-propyl alcohol and 2,000 parts by mass of propylene glycol monomethyl ether acetate.

[0241] The hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3 mass%) had an average particle diameter of 84.0 nm. The hollow particles contained in the obtained hollow particle propylene glycol monomethyl ether acetate dispersion had a shell density of 1.27 g / cm ３ The binder had a hollow fraction of 37.0% by volume and an absorbance ratio η (A1100 / A1720) of 0.831. The proportion of the phosphate ester compound after solvent washing (the content of the phosphate ester compound adhered to the outer surfaces of the shells of the hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion obtained in Example 3) was 21.7% by mass.

[0242] Comparative Example 1 To a 10 L stainless steel beaker, 120 parts by mass of polyoxyethylene alkyl ether phosphate (Phosphanol RS-710 manufactured by Toho Chemical Industry Co., Ltd.) as a phosphate ester compound was added, and the mixture was dissolved with 1000 parts by mass of n-propyl alcohol, 600 parts by mass of propylene glycol monomethyl ether, and 2000 parts by mass of propylene glycol monomethyl ether acetate.

[0243] Further, 2000 parts by mass of the hollow particle aqueous dispersion A (solid content = 10% by mass) obtained in Production Example 1 was added, and the mixture was stirred at room temperature for 15 minutes using an ultrasonic homogenizer to obtain a hollow particle alcohol-based dispersion. Note that the "hollow particle alcohol-based dispersion" refers to a dispersion in which hollow particles are dispersed in a mixed solution of n-propyl alcohol, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

[0244] The hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content = 0.3 mass%) had an average particle diameter of 656 nm. The hollow particles contained in the obtained hollow particle alcohol-based dispersion had a shell density of 1.27 g / cm. ３The binder had a hollow fraction of 30.9% by volume and an absorbance ratio η (A1100 / A1720) of 0.777. The proportion of the phosphate ester compound after solvent washing (the content of the phosphate ester compound adhered to the outer surfaces of the shells of the hollow particles contained in the hollow particle alcohol-based dispersion obtained in Comparative Example 1) was 20.1% by mass.

[0245] Comparative Example 2 To a 10 L stainless steel beaker, 120 parts by mass of polyoxyethylene alkyl ether phosphate (Phosphanol RS-710 manufactured by Toho Chemical Industry Co., Ltd.) as a phosphate ester compound was added, and the mixture was dissolved with 1000 parts by mass of n-propyl alcohol, 600 parts by mass of propylene glycol monomethyl ether, and 2000 parts by mass of propylene glycol monomethyl ether acetate.

[0246] Further, 2000 parts by mass of the hollow particle aqueous dispersion A (solid content = 10% by mass) obtained in Production Example 1 was added, and the mixture was stirred at room temperature for 15 minutes using an ultrasonic homogenizer.

[0247] The stirred hollow particle dispersion was transferred to a 10 L reactor and stirred at 70°C for 5 hours, and then cooled to room temperature to obtain a hollow particle alcohol-based dispersion. Note that the "hollow particle alcohol-based dispersion" refers to a dispersion in which hollow particles are dispersed in a mixed solution of n-propyl alcohol, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

[0248] The hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content = 0.3 mass%) had an average particle diameter of 352 nm. The hollow particles contained in the obtained hollow particle alcohol-based dispersion had a shell density of 1.27 g / cm. ３ The binder had a hollow fraction of 30.9% by volume and an absorbance ratio η (A1100 / A1720) of 0.786. The proportion of the phosphate ester compound after solvent washing (the content of the phosphate ester compound attached to the outer surfaces of the shells of the hollow particles contained in the hollow particle alcohol-based dispersion obtained in Comparative Example 2) was 20.2% by mass.

[0249] Table 2 shows the blending compositions and physical properties of the examples and comparative examples.

[0250] In Table 2, "at the time of charging raw materials" means the time point after 15 minutes of stirring at room temperature using an ultrasonic homogenizer. "Proportion of phosphate ester compound at the time of charging raw materials" means the proportion (mass %) of the amount of phosphate ester compound to the total amount of the amount of phosphate ester compound and the solid content in hollow particle aqueous dispersion A (solid content concentration = 10 mass %) at the time of charging raw materials.

[0251]

[0252] [Discussion of the results in Table 2] Comparison of the values ​​of "average particle diameter of hollow particles contained in hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3 mass%)" in Examples 1 to 3 in Table 2 with those in Comparative Examples 1 and 2 showed that the hollow particles obtained in Examples 1 to 3 were able to suppress aggregation of hollow particles in a dispersion medium.

[0253] A comparison of the "binder hollowness" values ​​in Examples 1 to 3 in Table 2 with those in Comparative Examples 1 and 2 shows that the hollow particles obtained in Examples 1 to 3 can prevent the hollow portions from collapsing due to deformation.

[0254] In Examples 1 to 3, it is presumed that an esterification reaction occurred on the outer surface of the hollow particle shell due to vacuum distillation, resulting in the phosphate ester compound being chemically attached to the outer surface of the hollow particle shell. It is also presumed that the hollow particles obtained in Examples 1 to 3 had the phosphate ester compound chemically attached to the outer surface of the shell by the esterification reaction and the phosphate ester compound attached via electrostatic interaction.

[0255] On the other hand, in Comparative Examples 1 and 2, distillation under reduced pressure was not performed, and therefore, an esterification reaction did not occur on the outer surface of the shell of the hollow particles. As a result, it is presumed that the phosphate ester compound adhered to the outer surface of the shell of the hollow particles via electrostatic interaction.

[0256] In Examples 1 to 3, it is believed that the chemical adhesion of the phosphate ester compound to the outer surface of the shell of the hollow particles prevented the phosphate ester from temporarily detaching, thereby increasing the dispersibility (i.e., the average particle size of the hollow particles contained in the hollow particle propylene glycol monomethyl ether acetate dispersion (solid content concentration = 0.3% by mass) became smaller).

Claims

1. A hollow particle having a shell and a hollow portion surrounded by the shell, the hollow particle having a surface that has been subjected to an esterification treatment.

2. The hollow particles according to claim 1, wherein the surfaces of the hollow particles have been esterified with a phosphoric acid ester compound.

3. The hollow particles according to claim 2, wherein the phosphate ester compound is a compound represented by the following formula (1): (In formula (1), R １ represents a linear or branched alkyl group having 3 to 19 carbon atoms, a linear or branched alkoxy group having 3 to 19 carbon atoms, an allyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, or a styryl group. ２ represents a hydrogen atom or a methyl group; m represents a number of 0 to 30; and n represents 1 or 2.

4. The hollow particle according to claim 1, wherein the shell contains a (meth)acrylic resin, and the (meth)acrylic resin includes a polymer derived from a (meth)acrylic reactive monomer having an epoxy group and / or a polymer derived from a (meth)acrylic reactive monomer having an oxetane group.

5. The hollow particles according to claim 1, wherein the ratio η of the absorbance (A1100) to the absorbance (A1720) in the infrared absorption spectrum obtained by measuring the hollow particles by ATR-FTIR (absorbance ratio η: A1100 / A1720) is 0.800 or more and 2.000 or less.

6. The hollow particle of claim 1, wherein the shell comprises an inorganic component.

7. The hollow particles according to claim 1, having an average particle size of 10 to 200 nm.

8. The hollow particles according to claim 1, having a void ratio of 31.0 to 70% by volume.

9. A dispersion comprising the hollow particles according to any one of claims 1 to 8.

10. A coating agent comprising the hollow particles according to any one of claims 1 to 8.

11. A heat insulating film comprising the hollow particles according to any one of claims 1 to 8.

12. An anti-reflection film comprising the hollow particles according to any one of claims 1 to 8.

13. A light extraction film comprising the hollow particles according to any one of claims 1 to 8.

14. A low dielectric constant film comprising the hollow particles according to any one of claims 1 to 8.

15. A photosensitive resin composition comprising the hollow particles according to any one of claims 1 to 8.

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