Method for producing hollow microparticles, hollow microparticles, phase-separated microparticles, aqueous dispersion and composition

Abstract

To provide a production method capable of producing hollow fine particles which contain a perfluororesin, have a large particle diameter and have a single hole structure.SOLUTION: A method for producing hollow fine particles includes: a step A of dispersing a solution which contains a perfluoromonomer, and a non-polymerizable solvent that can dissolve the perfluoromonomer and has an SP value of 9.00 to 9.80 (cal / cm3)1 / 2, in water, to obtain a dispersion liquid; a step B of polymerizing the perfluoromonomer to obtain phase separation fine particles which contain a perfluororesin and have a single hole structure; and a step C of removing the non-polymerizable solvent in the phase separation fine particles to obtain hollow fine particles having a single hole structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing hollow microparticles, hollow microparticles, phase-separated microparticles, aqueous dispersions, and compositions. [Background technology]

[0002] Hollow microparticles having voids inside the particles are excellent in terms of weight reduction, low refractive index, low dielectric properties, etc., and various studies are being conducted on them. Conventionally, inorganic particles have been used as such hollow microparticles, but because inorganic particles are heavy, hollow microparticles made of polymers have recently been studied as an alternative to inorganic particles.

[0003] For example, Patent Document 1 describes hollow resin microparticles containing a resin having fluorine atoms, characterized by an average particle size of 10 to 200 nm, a porosity of 10% or more, and a refractive index of 1.30 or less.

[0004] Patent Document 2 describes hollow fine particles that contain a fluorine-containing resin and have an average particle size of 70 nm or more and 10 μm or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-213366 [Patent Document 2] Japanese Patent Publication No. 2020-183500 Summary of the Invention [Problem to be solved by the invention]

[0006] However, hollow fine particles with a small particle size have problems in terms of handling, and therefore it has been desired to increase the particle size to improve the handling properties. Furthermore, it has been difficult to produce hollow microparticles containing perfluororesin and having a single-pore structure.

[0007] The present disclosure provides a production method capable of producing hollow microparticles that contain a perfluororesin, have a large average particle size, and have a single-pore structure. The present disclosure also provides hollow microparticles that contain a perfluororesin, have a large average particle size, and have a single-pore structure, and a composition that contains the hollow microparticles. The present disclosure also provides phase-separated microparticles that contain a perfluororesin, have a large average particle size, and have a single-pore structure, and an aqueous dispersion and composition that contain the phase-separated microparticles. [Means for solving the problem]

[0008] The present disclosure (1) relates to a perfluoromonomer and a polymer capable of dissolving the perfluoromonomer and having an SP value of 9.00 to 9.80 (cal / cm 3 ) 1 / 2 A step A of dispersing a solution containing the non-polymerizable solvent in water to obtain a dispersion; a step B of polymerizing the perfluoromonomer to obtain phase-separated fine particles containing a perfluororesin and having a single-pore structure; a step C of removing the non-polymerizable solvent from the phase-separated fine particles to obtain hollow fine particles having a single-pore structure; The method for producing hollow microparticles includes the steps of:

[0009] The present disclosure (2) is the method for producing hollow microparticles according to the present disclosure (1), wherein in the step A, the dispersion contains an initiator having an ester group at its terminal.

[0010] The present disclosure (3) is the method for producing hollow microparticles according to the present disclosure (2), wherein the ester group is a group represented by -COOR (R is an unbranched alkyl group).

[0011] The present disclosure (4) is directed to the step A, wherein the dispersion contains a particle dispersion stabilizer, This is a method for producing hollow microparticles according to any one of the present disclosures (1) to (3), wherein the particle dispersion stabilizer contains at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1). General formula (α): CX 1 X 2 =CX 3 │ (CX 4 X 5 )a-(O)c-Rf-A (In the formula, X 1 , X 2 , X 3 , X 4 and X 5 are independently H, F, CH3 or CF3, and X 1 , X 2 , X 3 , X 4 and X 5 At least one of the groups is F. a and c may be the same or different and each represent 0 or 1. Rf represents a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A represents -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M represents H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. General formula (1): Rf§(X - ) j (M + ) j (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X - -COO - , -PO3 - , or -SO3 - and M+ is H + , NH4 + , an alkali metal ion, and j may be 1 or 2).

[0012] The present disclosure (5) is the method for producing hollow microparticles according to the present disclosure (4), wherein the particle dispersion stabilizer further contains at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

[0013] The present disclosure (6) is directed to the step A, wherein the dispersion contains a particle dispersion stabilizer, This is a method for producing hollow microparticles according to any one of the present disclosures (1) to (3), wherein the particle dispersion stabilizer contains at least one selected from the group consisting of a homopolymer of CF2=CFCF2CF2SO3H, a homopolymer of CF2=CF-OCF2CF2COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

[0014] The present disclosure (7) is the method for producing hollow microparticles according to any one of the present disclosures (1) to (6), wherein the perfluoromonomer is a perfluoroolefin.

[0015] The present disclosure (8) is a method for producing hollow microparticles according to the present disclosure (7), wherein the perfluoroolefin contains a monofunctional monomer having one polymerizable reactive group and / or a polyfunctional monomer having two or more polymerizable reactive groups.

[0016] The present disclosure (9) relates to the perfluoroolefin, which contains the monofunctional monomer and the polyfunctional monomer, The method for producing hollow microparticles according to the present disclosure (8), wherein in the perfluororesin, the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 75 / 25 to 25 / 75.

[0017] The present disclosure (10) is a method for producing a polymerizable composition comprising the steps of: In the method for producing hollow microparticles according to the present disclosure (8) or (9), the polyfunctional monomer is a monomer represented by the following (b): CF2=CF-Q 1 -CF=CF2(b) [In the formula, Q 1 is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.]

[0018] The present disclosure (11) is the method for producing hollow microparticles according to the present disclosure (10), wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): [ka] [In the formula, R 12 ~R 15 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0019] The present disclosure (12) is the method for producing hollow microparticles according to the present disclosure (11), wherein the perfluoroolefin is a monomer represented by the formula (c).

[0020] The present disclosure (13) is a method for producing a polymerizable composition comprising the steps of: (1) preparing a polymerizable composition comprising: a polymerizable monomer (polymerizable copolymer) of a polymerizable compound (polymerizable copolymer) and a polymerizable copolymer (polymerizable copolymer); the polyfunctional monomer is at least one selected from the group consisting of CF═CF—O—(CF)—O—CF=CF and CF═CFCFCFOCF=CF, The method for producing hollow microparticles according to the present disclosure (9), wherein in the perfluororesin, the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 70 / 30 to 30 / 70.

[0021] The present disclosure (14) is the method for producing hollow microparticles according to any one of the present disclosures (1) to (13), wherein in the step B, the perfluororesin has a glass transition temperature of 60° C. or higher.

[0022] The present disclosure (15) is the method for producing hollow microparticles according to the present disclosure (14), wherein in the step B, the perfluororesin has a glass transition temperature of 120° C. or higher.

[0023] The present disclosure (16) is the method for producing hollow microparticles according to any one of the present disclosures (1) to (15), wherein the non-polymerizable solvent is a non-polymerizable fluorine-containing solvent.

[0024] The present disclosure (17) is the method for producing hollow microparticles according to the present disclosure (16), wherein the non-polymerizable fluorine-containing solvent is a fluorine-containing alcohol.

[0025] The present disclosure (18) is the method for producing hollow microparticles according to the present disclosure (17), wherein the fluorine-containing alcohol has 2 to 7 carbon atoms.

[0026] The present disclosure (19) is a method for producing hollow microparticles according to the present disclosure (17) or (18), wherein the fluorine-containing alcohol has a hydrogen atom at the ω-position.

[0027] The present disclosure (20) is a method for producing hollow microparticles according to any one of the present disclosures (1) to (15), wherein the non-polymerizable solvent is at least one selected from the group consisting of H(CF2)6CH2OH, F(CF2)3CH2OH, and F(CF2)4CH2OH.

[0028] The present disclosure (21) is the method for producing hollow microparticles according to any one of the present disclosures (1) to (20), wherein the hollow microparticles have an average particle size of 1.0 μm or more.

[0029] The present disclosure (22) is the method for producing hollow microparticles according to any one of the present disclosures (1) to (21), wherein the hollow microparticles have a porosity of 30% by volume or more.

[0030] The present disclosure (23) is the method for producing hollow microparticles according to the present disclosure (22), wherein the hollow microparticles have a porosity of 40% by volume or more.

[0031] The present disclosure (24) includes a perfluororesin containing polymerized units based on a perfluoromonomer, Substantially free of non-polymerizable solvents; The average particle size is 1.0 μm or more, These are hollow particles with a single-pore structure.

[0032] The present disclosure (25) is the hollow microparticle according to the present disclosure (24), wherein the perfluoromonomer is a perfluoroolefin.

[0033] The present disclosure (26) is the hollow microparticle according to the present disclosure (25), wherein the perfluoroolefin contains a monofunctional monomer having one polymerizable reactive group and / or a polyfunctional monomer having two or more polymerizable reactive groups.

[0034] The present disclosure (27) relates to the perfluoroolefin, which contains the monofunctional monomer and the polyfunctional monomer, The hollow microparticles according to the present disclosure (26), wherein the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) in the perfluororesin is 75 / 25 to 25 / 75.

[0035] The present disclosure (28) is directed to the method of the present invention, wherein the monofunctional monomer is a cyclic perfluoroolefin, The hollow microparticles according to the present disclosure (26) or (27) are those in which the polyfunctional monomer is a monomer represented by the following (b): CF2=CF-Q 1 -CF=CF2(b) [In the formula, Q 1 is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.]

[0036] The present disclosure (29) is the hollow microparticle according to the present disclosure (28), wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): [ka] [In the formula, R 12 ~R 15 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0037] The present disclosure (30) is the hollow microparticle according to the present disclosure (29), wherein the perfluoroolefin is a monomer represented by the formula (c).

[0038] The present disclosure (31) relates to a method for producing a polymerizable composition comprising the steps of: (1) preparing a polymerizable composition comprising a polymerizable monomer (polymerizable compound) and a polymerizable compound (polymerizable compound), wherein the monofunctional monomer is perfluoro(2-methylene-4-methyl-1,3-dioxolane); the polyfunctional monomer is at least one selected from the group consisting of CF═CF—O—(CF)—O—CF=CF and CF═CFCFCFOCF=CF, The hollow microparticles according to the present disclosure (27), wherein the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) in the perfluororesin is 70 / 30 to 30 / 70.

[0039] The present disclosure (32) is the hollow microparticle according to any one of the present disclosures (24) to (31), wherein the perfluororesin has a glass transition temperature of 60° C. or higher.

[0040] The present disclosure (33) is the hollow microparticle according to the present disclosure (32), wherein the glass transition temperature of the perfluororesin is 120° C. or higher.

[0041] The present disclosure (34) is the hollow microparticle according to any one of the present disclosures (24) to (33), which has a porosity of 30% by volume or more.

[0042] The present disclosure (35) is the hollow microparticle according to the present disclosure (34), which has a porosity of 40% by volume or more.

[0043] The present disclosure (36) is a method for manufacturing a polymer dispersion dispersion stabilizer, wherein the perfluororesin contains a particle dispersion stabilizer, The hollow microparticles are those according to any one of the present disclosures (24) to (35), wherein the particle dispersion stabilizer contains at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1). General formula (α): CX 1 X 2 =CX 3 │ (CX 4 X5 )a-(O)c-Rf-A (In the formula, X 1 , X 2 , X 3 , X 4 and X 5 are independently H, F, CH3 or CF3, and X 1 , X 2 , X 3 , X 4 and X 5 At least one of the groups is F. a and c may be the same or different and each represent 0 or 1. Rf represents a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A represents -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M represents H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. General formula (1): Rf§(X - ) j (M + ) j (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X - -COO - , -PO3 - , or -SO3 - and M + is H + , NH4 + , an alkali metal ion, and j may be 1 or 2).

[0044] The present disclosure (37) is the hollow microparticle according to the present disclosure (36), wherein the particle dispersion stabilizer further comprises at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

[0045] The present disclosure (38) is a method for manufacturing a polymer dispersion dispersion stabilizer, wherein the perfluororesin contains a particle dispersion stabilizer, The hollow microparticles are according to any one of the present disclosures (24) to (35), wherein the particle dispersion stabilizer comprises at least one selected from the group consisting of a homopolymer of CF2=CFCF2CF2SO3H, a homopolymer of CF2=CF-OCF2CF2COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

[0046] The present disclosure (39) is the hollow microparticle according to any one of the present disclosures (24) to (38), wherein the non-polymerizable solvent is at least one selected from the group consisting of H(CF2)6CH2OH, F(CF2)3CH2OH, and F(CF2)4CH2OH.

[0047] The present disclosure (40) is the hollow fine particle according to any one of the present disclosures (24) to (39) for use as an electronic material.

[0048] The present disclosure (41) provides a polymerizable composition comprising a perfluororesin containing polymerized units based on a perfluoromonomer and a non-polymerizable solvent, The average particle size is 1.0 μm or more, These are phase-separated particles with a single-pore structure.

[0049] The present disclosure (42) is the phase-separated microparticles according to the present disclosure (41), wherein the perfluoromonomer is a perfluoroolefin.

[0050] The present disclosure (43) is the phase-separated microparticles according to the present disclosure (42), wherein the perfluoroolefin contains a monofunctional monomer having one polymerizable reactive group and / or a polyfunctional monomer having two or more polymerizable reactive groups.

[0051] The present disclosure (44) relates to a method for producing a polymerizable composition comprising the perfluoroolefin, the perfluoroolefin comprising the monofunctional monomer and the polyfunctional monomer; The phase-separated microparticles according to the present disclosure (43) are such that in the perfluororesin, the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 75 / 25 to 25 / 75.

[0052] The present disclosure (45) is directed to a method for producing a polymerizable composition comprising the steps of: The phase-separated fine particles according to the present disclosure (43) or (44) are those in which the polyfunctional monomer is a monomer represented by the following (b): CF2=CF-Q 1 -CF=CF2(b) [In the formula, Q 1 is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.]

[0053] The present disclosure (46) is the phase-separated microparticles according to the present disclosure (45), wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): [ka] [In the formula, R 12 ~R 15 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0054] The present disclosure (47) is the phase-separated microparticles according to the present disclosure (46), wherein the perfluoroolefin is a monomer represented by the formula (c).

[0055] The present disclosure (48) relates to a method for producing a polymerizable composition comprising the steps of: (1) preparing a polymerizable composition comprising a polymerizable monomer (polymerizable compound) and a polymerizable compound (polymerizable compound), wherein the monofunctional monomer is perfluoro(2-methylene-4-methyl-1,3-dioxolane); the polyfunctional monomer is at least one selected from the group consisting of CF═CF—O—(CF)—O—CF=CF and CF═CFCFCFOCF=CF, The phase-separated microparticles according to the present disclosure (44) are such that in the perfluororesin, the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 70 / 30 to 30 / 70.

[0056] The present disclosure (49) is the phase-separated microparticles according to any one of the present disclosures (41) to (48), wherein the perfluororesin has a glass transition temperature of 60° C. or higher.

[0057] The present disclosure (50) is the phase-separated microparticles according to the present disclosure (49), wherein the glass transition temperature of the perfluororesin is 120° C. or higher.

[0058] The present disclosure (51) is the phase-separated microparticles according to any one of the present disclosures (41) to (50), which have a porosity of 30% by volume or more.

[0059] The present disclosure (52) is the phase-separated microparticles according to the present disclosure (51), which have a porosity of 40% by volume or more.

[0060] The present disclosure (53) is a method for manufacturing a polymer dispersion dispersion stabilizer, wherein the perfluororesin contains a particle dispersion stabilizer, The phase-separated microparticles are described in any one of the present disclosures (41) to (52), wherein the particle dispersion stabilizer contains at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1). General formula (α): CX 1 X 2 =CX 3 │ (CX 4 X 5 )a-(O)c-Rf-A (In the formula, X 1 , X 2 , X 3 , X 4 and X 5 are independently H, F, CH3 or CF3, and X 1 , X 2 , X 3 , X 4 and X 5 At least one of the groups is F. a and c may be the same or different and each represent 0 or 1. Rf represents a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A represents -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M represents H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. General formula (1): Rf§(X - ) j (M + ) j (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X - -COO - , -PO3 - , or -SO3 - and M+ is H + , NH4 + , an alkali metal ion, and j may be 1 or 2).

[0061] The present disclosure (54) is the phase-separated microparticles according to the present disclosure (53), wherein the particle dispersion stabilizer further comprises at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

[0062] The present disclosure (55) is a method for manufacturing a polymer dispersion dispersion stabilizer, wherein the perfluororesin contains a particle dispersion stabilizer, The phase-separated microparticles according to any one of the present disclosures (41) to (52) are characterized in that the particle dispersion stabilizer contains at least one selected from the group consisting of a homopolymer of CF2=CFCF2CF2SO3H, a homopolymer of CF2=CF-OCF2CF2COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

[0063] The present disclosure (56) is the phase-separated microparticles according to any one of the present disclosures (41) to (55), wherein the non-polymerizable solvent is at least one selected from the group consisting of H(CF2)6CH2OH, F(CF2)3CH2OH, and F(CF2)4CH2OH.

[0064] The present disclosure (57) is an aqueous dispersion containing the phase-separated fine particles according to any one of the present disclosures (41) to (56).

[0065] The present disclosure (58) is a composition containing the hollow fine particles according to any one of the present disclosures (24) to (40) and an insulating resin.

[0066] The present disclosure (59) is a composition containing the phase-separated fine particles according to any one of the present disclosures (41) to (56) and an insulating resin. [Effects of the Invention]

[0067] The manufacturing method of the present disclosure can produce hollow microparticles that contain a perfluororesin, have a large average particle size, and have a single-pore structure. The hollow fine particles and the phase-separated fine particles of the present disclosure have a large average particle size despite containing a perfluororesin. [Brief explanation of the drawings]

[0068] [Figure 1] 1 is an optical microscope photograph of the particles (monoporous bodies) dispersed and suspended in water obtained in Example 1. [Figure 2] 1 is an SEM photograph of hollow fine particles (single-porous bodies) obtained in Example 2. [Figure 3] 1 is an SEM photograph of a cross section of a hollow fine particle (single-porous body) obtained in Example 2. [Figure 4] 1 is an optical microscope photograph of the particles (monoporous bodies) dispersed and suspended in water obtained in Example 3. [Figure 5] 1 is an SEM photograph of a cross section of a hollow fine particle (single-porous body) obtained in Example 6. [Figure 6] 1 is an SEM photograph of hollow fine particles (porous bodies) obtained in Comparative Example 5. [Figure 7] 1 is an SEM photograph of hollow fine particles (aggregates of fine particles (a type of porous body)) obtained in Comparative Example 7. [Figure 8] 1 is an SEM photograph of hollow fine particles (porous bodies) obtained in Comparative Example 8. [Figure 9] 1 is an optical microscope photograph of hollow fine particles (aggregates of fine particles (a type of porous body)) obtained in Comparative Example 9. [Figure 10] 1 is an optical microscope photograph of the particles dispersed and suspended in water obtained in Comparative Example 10 (the structure is reversed from that of Example 1). [Figure 11] 1 is an optical microscope photograph of the particles (porous body) dispersed in water obtained in Comparative Example 11. [Figure 12] 1 is an optical microscope photograph of the particles dispersed and suspended in water obtained in Comparative Example 12 (the structure is reversed from that of Example 1). [Figure 13]1 is an optical microscope photograph of the particles (monoporous bodies) dispersed and suspended in water obtained in Example 7. [Figure 14] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 9. [Figure 15] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 11. [Figure 16] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 13. [Figure 17] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 15. [Figure 18] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 17. [Figure 19] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 19. DETAILED DESCRIPTION OF THE INVENTION

[0069] Before specifically describing the present disclosure, some terms used in the present disclosure will be defined or explained.

[0070] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, a heteroaryl group optionally having one or more substituents; cyano group, formyl group, RaO-, RaCO-, RaSO2-, RaCOO-, RaNRaCO-, RaCONRa-, RaOCO-, RaOSO2-, and RaNRbSO2- (In these formulas, Ra independently represents: an alkyl group optionally having one or more substituents; an alkenyl group optionally having one or more substituents; an alkynyl group optionally having one or more substituents; a cycloalkyl group optionally having one or more substituents; a cycloalkenyl group optionally having one or more substituents, a cycloalkadienyl group optionally having one or more substituents, an aryl group optionally having one or more substituents; an aralkyl group optionally having one or more substituents; a non-aromatic heterocyclic group optionally having one or more substituents, or a heteroaryl group optionally having one or more substituents; Rb is independently H or an alkyl group which may have one or more substituents. Includes. The organic group is preferably an alkyl group which may have one or more substituents.

[0071] In the present disclosure, the term "substituent" refers to a substitutable group. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamido group, an aromatic sulfonamido group, a heterocyclic sulfonamido group, an amino group, These include an aliphatic amino group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxy group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, and a diaromatic oxyphosphinyl group.

[0072] The aliphatic group may be saturated or unsaturated and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic group include alkyl groups having a total of 1 to 8, preferably 1 to 4, carbon atoms, such as a methyl group, an ethyl group, a vinyl group, a cyclohexyl group, and a carbamoylmethyl group.

[0073] The aromatic group may have, for example, a nitro group, a halogen atom, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic group include aryl groups having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in total, such as a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0074] The heterocyclic group may have a halogen atom, a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the heterocyclic group include a 5- or 6-membered heterocycle having a total of 2 to 12, preferably 2 to 10, carbon atoms, such as a 2-tetrahydrofuryl group and a 2-pyrimidyl group.

[0075] The acyl group may have an aliphatic carbonyl group, an arylcarbonyl group, a heterocyclic carbonyl group, a hydroxy group, a halogen atom, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the acyl group include acyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as an acetyl group, a propanoyl group, a benzoyl group, and a 3-pyridinecarbonyl group.

[0076] The acylamino group may have an aliphatic group, an aromatic group, a heterocyclic group, etc., such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include acylamino groups having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and alkylcarbonylamino groups having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0077] The aliphatic oxycarbonyl group may be saturated or unsaturated and may have a hydroxy group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic oxycarbonyl group include alkoxycarbonyl groups having a total of 2 to 8, preferably 2 to 4, carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, and a (t)-butoxycarbonyl group.

[0078] The carbamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the carbamoyl group include an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 9 carbon atoms, preferably an unsubstituted carbamoyl group, an alkylcarbamoyl group having a total of 2 to 5 carbon atoms, such as an N-methylcarbamoyl group, an N,N-dimethylcarbamoyl group, and an N-phenylcarbamoyl group.

[0079] The aliphatic sulfonyl group may be saturated or unsaturated and may have a hydroxy group, an aromatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aliphatic sulfonyl group include alkylsulfonyl groups having a total of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as a methanesulfonyl group.

[0080] The aromatic sulfonyl group may have a hydroxy group, an aliphatic group, an aliphatic oxy group, a carbamoyl group, an aliphatic oxycarbonyl group, an aliphatic thio group, an amino group, an aliphatic amino group, an acylamino group, a carbamoylamino group, etc. Examples of the aromatic sulfonyl group include arylsulfonyl groups having a total of 6 to 10 carbon atoms, such as a benzenesulfonyl group.

[0081] The amino group may have an aliphatic group, an aromatic group, a heterocyclic group, or the like.

[0082] The acylamino group may have, for example, an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc. Examples of the acylamino group include an acylamino group having a total of 2 to 12 carbon atoms, preferably a total of 2 to 8 carbon atoms, and more preferably an alkylcarbonylamino group having a total of 2 to 8 carbon atoms, such as an acetylamino group, a benzoylamino group, a 2-pyridinecarbonylamino group, a propanoylamino group, etc.

[0083] The aliphatic sulfonamide group, aromatic sulfonamide group, and heterocyclic sulfonamide group may be, for example, a methanesulfonamide group, a benzenesulfonamide group, or a 2-pyridinesulfonamide group.

[0084] The sulfamoyl group may have an aliphatic group, an aromatic group, a heterocyclic group, etc. Examples of the sulfamoyl group include a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 9 carbon atoms, a dialkylsulfamoyl group having a total of 2 to 10 carbon atoms, an arylsulfamoyl group having a total of 7 to 13 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 12 carbon atoms, more preferably a sulfamoyl group, an alkylsulfamoyl group having a total of 1 to 7 carbon atoms, a dialkylsulfamoyl group having a total of 3 to 6 carbon atoms, an arylsulfamoyl group having a total of 6 to 11 carbon atoms, and a heterocyclic sulfamoyl group having a total of 2 to 10 carbon atoms, such as a sulfamoyl group, a methylsulfamoyl group, an N,N-dimethylsulfamoyl group, a phenylsulfamoyl group, and a 4-pyridine sulfamoyl group.

[0085] The aliphatic oxy group may be saturated or unsaturated and may have a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, a methoxyethoxy group, etc. Examples of the aliphatic oxy group include alkoxy groups having a total of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an i-propyloxy group, a cyclohexyloxy group, and a methoxyethoxy group.

[0086] The aromatic amino group and heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group fused with the aryl group, or an aliphatic oxycarbonyl group, preferably an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic oxy group having 1 to 4 carbon atoms in total, a halogen atom, a carbamoyl group having 1 to 4 carbon atoms in total, a nitro group, or an aliphatic oxycarbonyl group having 2 to 4 carbon atoms in total.

[0087] The aliphatic thio group may be saturated or unsaturated, and examples thereof include alkylthio groups having a total of 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group, an ethylthio group, a carbamoylmethylthio group, and a t-butylthio group.

[0088] The carbamoylamino group may have an aliphatic group, an aryl group, a heterocyclic group, etc. Examples of the carbamoylamino group include a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 9 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 10 carbon atoms, an arylcarbamoylamino group having a total of 7 to 13 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 12 carbon atoms, preferably a carbamoylamino group, an alkylcarbamoylamino group having a total of 2 to 7 carbon atoms, a dialkylcarbamoylamino group having a total of 3 to 6 carbon atoms, an arylcarbamoylamino group having a total of 7 to 11 carbon atoms, and a heterocyclic carbamoylamino group having a total of 3 to 10 carbon atoms, such as a carbamoylamino group, a methylcarbamoylamino group, an N,N-dimethylcarbamoylamino group, a phenylcarbamoylamino group, and a 4-pyridinecarbamoylamino group.

[0089] In this disclosure, ranges expressed by endpoints include all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0090] In this disclosure, the term "at least 1" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0091] (Method for producing hollow microparticles) The manufacturing method of the present disclosure is a method for producing a perfluoromonomer and a polymerizable polymer capable of dissolving the perfluoromonomer and having an SP value of 9.00 to 9.80 (cal / cm 3 ) 1 / 2 The method includes a step A of dispersing a solution containing the non-polymerizable solvent in water to obtain a dispersion, a step B of polymerizing the perfluoromonomer to obtain phase-separated microparticles containing a perfluororesin and having a single-pore structure, and a step C of removing the non-polymerizable solvent from the phase-separated microparticles to obtain hollow microparticles having a single-pore structure.

[0092] The present inventors have conducted studies and found that when perfluoromonomers are polymerized to obtain hollow microparticles containing perfluororesin, it is difficult to obtain hollow microparticles having a large average particle size and a single-pore structure using conventional methods. The present inventors have found that the above-described steps A to C can be used to obtain hollow microparticles containing perfluororesin, having a large average particle size and a single-pore structure, and have completed the production method of the present disclosure.

[0093] In step A, perfluoromonomers and perfluoromonomers can be dissolved and the SP value is 9.00 to 9.80 (cal / cm 3 ) 1 / 2 This is a process of dispersing a solution containing the non-polymerizable solvent in water to obtain a dispersion. By dispersing the solution in water, droplets are formed, and by polymerizing the perfluoromonomer in these droplets, phase-separated microparticles with a large average particle size and a single-pore structure can be obtained. Then, by removing the non-polymerizable solvent from the phase-separated microparticles, hollow microparticles with a large average particle size and a single-pore structure can be obtained. In the production method of the present disclosure, the shells of the hollow microparticles are formed from a perfluororesin. Hereinafter, in this specification, a resin containing a constitutional unit based on a perfluoromonomer will be referred to as a perfluororesin.

[0094] The reason why the single-hole structure is formed by the manufacturing method of the present disclosure is presumed to be as follows. In step A, the polymerized polymer (perfluororesin) precipitates on the surface of the droplets and diffuses, forming phase-separated microparticles. Since water is present outside the droplets, if the polymer is highly hydrophobic, the polymer precipitates not only on the surface of the droplets but also inside the droplets, which is thought to prevent sufficient phase separation and result in the formation of phase-separated microparticles with a porous structure. In contrast, in the manufacturing method of the present disclosure, the SP value is 9.00 to 9.80 (cal / cm 3 ) 1 / 2 By using a non-polymerizable solvent, hydrophilic groups are introduced to the polymer terminals, resulting in a polymer with highly hydrophilic terminals. This promotes the precipitation of the polymer on the droplet surface, and the phase separation proceeds sufficiently, resulting in the formation of phase-separated microparticles with a single-pore structure.

[0095] A dispersion medium other than water may be used together with water in step A. The dispersion medium other than water is not particularly limited as long as it is miscible with water and can produce a dispersion liquid in step A, and examples thereof include dimethylformamide, dimethyl sulfoxide, dimethylacetamide, n-methylpyrrolidone, methanol, ethanol, propanol, and isopropanol.

[0096] Examples of perfluoromonomers include perfluoroacrylic monomers, perfluorostyrene monomers, and perfluoroolefins, with perfluoroolefins being preferred.

[0097] The perfluoroolefin is not particularly limited, but a monofunctional monomer having one polymerizable reactive group and / or a polyfunctional monomer having two or more (preferably 2 to 4) polymerizable reactive groups can be used. It is preferable to use at least a monofunctional monomer, and it is preferable to use a combination of a monofunctional monomer and a polyfunctional monomer.

[0098] A cyclic perfluoroolefin can be suitably used as the monofunctional monomer, and a monomer (cyclopolymerizable monomer) represented by the following formula (b) can be suitably used as the polyfunctional monomer. By using these monomers, a cyclic structure is introduced into the main chain of the polymer, resulting in a polymer with a high glass transition temperature. CF2=CF-Q 1 -CF=CF2(b) [In the formula, Q 1 is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.]

[0099] The cyclic perfluoroolefin is a highly fluorine-substituted olefin having a cyclic structure. The cyclic perfluoroolefin is not particularly limited, but the following monomers represented by (a) or (c) can be suitably used: [ka] [In the formula, R 12 ~R 15 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0100] Specific examples of the monomer represented by formula (a) include the monomers represented by the following (a-1) to (a-5), and specific examples of the monomer represented by formula (c) include the monomers represented by the following (a-6) to (a-7). [ka]

[0101] As the cyclic perfluoroolefin, from the viewpoint of good electrical properties, a monomer represented by formula (c) is preferred, a monomer represented by formulas (a-6) to (a-7) is more preferred, and a monomer represented by formula (a-7) is even more preferred. 16 ~R 19 It is preferred that three of the groups are fluorine atoms and one is a perfluoromethyl group.

[0102] In equation (b), Q 1 It is preferable that the perfluoroalkylene group has an ether bond. In this case, the ether bond in the perfluoroalkylene group may be present at one end of the group, may be present at both ends of the group, or may be present between carbon atoms of the group. In terms of excellent cyclopolymerization properties, it is preferable that the ether bond be present at one end of the group.

[0103] Examples of the monomer represented by formula (b) include perfluoro(3-butenyl vinyl ether), perfluoro(aryl vinyl ether), perfluoro(3,5-dioxaheptadiene), perfluoro(3,5-dioxa-4,4-dimethylheptadiene), etc. Perfluoro(3-butenyl vinyl ether) is particularly preferred.

[0104] The monomer represented by formula (b) is CF2=CF-O-(CF2) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2) m -CF=CF2 (in the formula, m=1~20), CF2=CF-(O-CF2CF(CF3)) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2) n -CF=CF2 (wherein n=1 to 20) and the like are also included. Among these, CF2=CF-O-(CF2) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2)m -CF=CF2 (wherein m=1 to 20) is preferred, and CF2=CF-O-(CF2) n -O-CF=CF2 (in the formula, n=1~20), CF2=CF-(CF2) n -O-CF=CF2 (wherein n=1 to 20) is more preferred, and CF2=CF-O-(CF2) n -O-CF=CF2 (in the formula, n=1~5), CF2=CF-(CF2) n -O-CF=CF2 (wherein n=1 to 5) is more preferred, CF2=CF-O-(CF2)3-O-CF=CF2, CF2=CF-(CF2)2-O-CF=CF2 are even more preferred, and CF2=CF-O-(CF2)3-O-CF=CF2 is particularly preferred.

[0105] Furthermore, the monomer represented by formula (b) has two polymerizable reactive groups, and therefore can function as a crosslinking monomer. When functioning as a crosslinking monomer, the crosslinking effect is expected to improve the heat resistance, mechanical strength, and chemical resistance of the entire system. In particular, when forming a single-pore structure as in the present disclosure, this is preferable in terms of ensuring the strength of the shell layer.

[0106] Examples of units formed by cyclopolymerization of the monomer represented by formula (b) include the following formulae (II-1) to (II-4). As shown in the formulae below, in formulae (II-1) to (II-3), the four carbon atoms constituting the two double bonds constitute the main chain of the polymer, while in formula (II-4), only the two terminal carbon atoms constituting the two double bonds constitute the main chain of the polymer. Also, as in formula (II-1), two of the four carbon atoms constituting the two double bonds are Q 1 and may form an aliphatic ring together with Q, or as in formula (II-2) and formula (II-3), 1 and Q may form an aliphatic ring together, or as in formula (II-4), four double bonds may be 1 In addition, Q may form an aliphatic ring together with 1As the aliphatic ring containing the ring, five-membered and six-membered rings are likely to be produced, and the polymer produced by cyclopolymerization will be a polymer whose main unit is a unit having a five-membered or six-membered ring.

[0107] [ka]

[0108] As the monofunctional monomer other than the cyclic perfluoroolefin, a monomer represented by the following formula (d) can also be used. CR 20 R 21 =CR 22 R 23 (d) [In the formula, R 20 ~R 23 are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0109] Monomers represented by formula (d) include CF2=CF2, CF2=CF(CF3), CF2=CF(C2F5), CF2=CF(C3F7), CF2=CF(C4F9), CF2=CF(C5F 11 ), CF2=CF(OCF3), CF2=CF(OC2F5), CF2=CF(OC3F7), CF2=CF(OC4F9), CF2=CF(OC5F 11 Among these, CF2=CF2, CF2=CF(CF3), CF2=CF(OCF3), CF2=CF(OC2F5), and CF2=CF(OC3F7) are preferred.

[0110] In step A, the solution containing the perfluoromonomer and the non-polymerizable solvent may further contain a monomer copolymerizable with the perfluoromonomer. As the monomer copolymerizable with the perfluoromonomer, for example, a fluorine-containing monomer other than the perfluoromonomer, a non-fluorine-containing monomer, etc. can be used.

[0111] Examples of fluorine-containing monomers other than perfluoromonomers include fluorine-containing acrylic monomers (excluding perfluoroacrylic monomers), fluorine-containing styrene monomers (excluding perfluorostyrene monomers), and fluorine-containing olefins (excluding perfluoroolefins).

[0112] The non-fluorine-containing monomer may be a monofunctional monomer or a polyfunctional monomer.

[0113] Examples of the non-fluorine-containing monomers that fall under the category of polyfunctional monomers include di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane di(meth)acrylate; trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate; Tri(meth)acrylates such as pentaerythritol tri(meth)acrylate; diaryl compounds or triaryl compounds such as pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, diaryl phthalate, diaryl maleate, diaryl fumarate, diaryl succinate, and triaryl isocyanurate; divinylbenzene, butadiene, 1,6-hexanediol divinylate Divinyl compounds such as ethylene glycol di-α-fluoroacrylate, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, and triethylene glycol divinyl ether; di-α-fluoroacrylates such as ethylene glycol di-α-fluoroacrylate, diethylene glycol di-α-fluoroacrylate, triethylene glycol di-α-fluoroacrylate, 1,6-hexanediol di-α-fluoroacrylate, and trimethylolpropane di-α-fluoroacrylate; tri-α-fluoroacrylates such as trimethylolpropane tri-α-fluoroacrylate, ethylene oxide-modified trimethylolpropane tri-α-fluoroacrylate, and pentaerythritol tri-α-fluoroacrylate; tetra-α-fluoroacrylates such as pentaerythritol tetra-α-fluoroacrylate; and hexa-α-fluoroacrylates such as dipentaerythritol hexa-α-fluoroacrylate. These can be used alone or in combination of two or more. Among these, divinyl ethers such as 1,4-butanediol divinyl ether, cyclohexane dimethanol divinyl ether, and diethylene glycol divinyl ether are preferred.

[0114] Examples of fluorine-containing non-monomers that fall under the category of monofunctional monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cumyl (meth)acrylate, cyclohexyl (meth)acrylate, myristyl (meth)acrylate, pearlityl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylonitrile, (meth)acrylamide, (meth)acrylic acid, glycidyl (meth)acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. Examples of suitable monomers include polar group-containing (meth)acrylic monomers; aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, and p-chlorostyrene; vinyl esters such as vinyl acetate, vinyl benzoate, vinyl neononanoate (trade name Veova 9), vinyl neodecanoate (trade name Veova 10), and vinyl propionate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and hydroxybutyl vinyl ether; halogen-containing monomers such as vinyl chloride and vinylidene chloride; vinylpyridine, 2-acryloyloxyethyl phthalate, itaconic acid, fumaric acid, ethylene, propylene, and polydimethylsiloxane macromonomers. Among these, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and hydroxybutyl vinyl ether are preferred because they can impart appropriate toughness to the polymer. Furthermore, vinyl esters such as vinyl benzoate, vinyl neononanoate (trade name Veova 9), vinyl neodecanoate (trade name Veova 10), and vinyl propionate are preferred because they have improved compatibility with perfluoromonomers.

[0115] In step A, the solution containing the perfluoromonomer and the non-polymerizable solvent preferably has a monomer content of 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.8 to 3.5 parts by mass, per part by mass of the non-polymerizable solvent. The content of the monomer refers to the amount of perfluoromonomer used when only perfluoromonomer is polymerized, and refers to the total amount of perfluoromonomer and monomer copolymerizable with perfluoromonomer when both are polymerized. The proportion of each monomer may be appropriately set depending on the desired perfluororesin.

[0116] The non-polymerizable solvent can be a solvent that can dissolve the perfluoromonomer but has low compatibility with the resulting perfluororesin. Low compatibility with the resulting perfluororesin promotes phase separation of the resulting perfluororesin, making it possible to produce hollow microparticles.

[0117] In addition, non-polymerizable solvents have an SP value of 9.00 to 9.80 (cal / cm 3 ) 1 / 2 During polymerization of the perfluororesin, the non-polymerizable solvent functions as a chain transfer agent, and when the SP value is within this range, it is believed that a hydrophilic group is introduced into the terminal of the resulting perfluororesin. The lower limit of the SP value is preferably 9.20, more preferably 9.30, and the upper limit is preferably 9.60, more preferably 9.50. The SP value can be determined by Fedors' formula (Polym. Eng. Sci., 14[2], 147(1974)).

[0118] Examples of the non-polymerizable solvent include non-polymerizable fluorine-containing solvents such as fluorine-containing alcohols, and fluorine-containing alcohols are preferred.

[0119] The fluorine-containing alcohol is selected from the group consisting of fluorine-containing alcohols represented by the following formula: X-(CF2) n -(CH2) m -OH (X is H or F, n is 2 to 7, m is 1 or 2) The compounds represented by the formula (I) and having an SP value in the above range are preferred. Specific examples include those in the table below. The compound represented by this formula is F(CF2) n (CH2) m OH (n = 2 to 4, m = 1 or 2), H(CF2)n (CH2) m OH (n=5 to 7, m=1 or 2) is preferred, and H(CF2) n (CH2) m OH (n=5 to 7, m=1 or 2) is more preferred.

[0120] [Table 1]

[0121] Furthermore, the fluorine-containing alcohol preferably has a hydrogen atom at the ω-position, since this introduces a hydrophilic group into the terminal of the polymer (perfluororesin), further improving the hydrophilicity of the polymer. That is, compounds in which X=H in the above formula are preferred. Specific examples of fluorine-containing alcohols having a hydrogen atom at the ω-position include H(CF2)nCH2OH (n=5 to 7), with H(CF2)6CH2OH, F(CF2)3CH2OH, and F(CF2)4CH2OH being preferred, and H(CF2)6CH2OH being particularly preferred.

[0122] The non-polymerizable solvents may be used alone or in combination of two or more kinds. The non-polymerizable solvent may be mixed with other solvents as long as the properties are not impaired. The proportion of the non-polymerizable solvent in the total amount of solvents is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit is not particularly limited, and may be 100% by mass.

[0123] The amount of the non-polymerizable solvent used can be appropriately selected from a wide range, but is generally 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, per part by mass of the monomer.

[0124] In step A, the dispersion preferably contains a particle dispersion stabilizer. By containing a particle dispersion stabilizer, phase separation can be further promoted, and hollow fine particles with a large particle size can be obtained. The particle dispersion stabilizer may be mixed with water in advance before step A, or may be mixed with a solution containing a perfluoromonomer and a non-polymerizable solvent in advance, or may be added to water in step A separately from the solution.

[0125] As the particle dispersion stabilizer, a wide range of substances can be used that have the effect of preventing coalescence of droplets formed by dispersing a solution containing a monomer component, a phase separation promoter, and a non-polymerizable solvent in water, and examples thereof include polymer dispersion stabilizers and fluorine-containing particle dispersion stabilizers.

[0126] Examples of polymer dispersion stabilizers include polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer, etc. Among these, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and polymethacrylic acid are preferred, polyvinyl alcohol and polyvinylpyrrolidone are more preferred, and polyvinyl alcohol is even more preferred.

[0127] The fluorine-containing particle dispersion stabilizer may, for example, be a fluoropolymer (α) of a monomer (α) represented by the general formula (α). General formula (α): CX 1 X 2 =CX 3 │ (CX 4 X 5 )a-(O)c-Rf-A (In the formula, X 1 , X 2 , X 3 , X 4 and X 5 are independently H, F, CH3 or CF3, and X 1 , X 2 , X 3 , X 4 and X 5At least one of the groups is F. a and c may be the same or different and each represent 0 or 1. Rf represents a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A represents -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M represents H, a metal atom, NR 7 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group. When a is 1, c is preferably 1, and X 1 and X 2 is preferably H or F, more preferably H. 3 , X 4 and X 5 is preferably H or F, more preferably F. When a is 0, c is preferably 1, and X 1 and X 2 is preferably H or F, more preferably F. 3 , X 4 and X 5 is preferably H or F, and more preferably F. That is, the monomer (α) is preferably at least one selected from (formula 1a) CF2=CF-O-Rf-A and (formula 2a) CH2=CF-CF2-O-Rf-A, since this further improves the water solubility of the fluoropolymer. In the formula, when Rf is a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, it is an alkylene group that does not contain a structure in which an oxygen atom is at the terminal and contains an ether bond between carbon atoms.

[0128] The number of carbon atoms in the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms in the fluorine-containing alkylene group is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, particularly preferably 6 or less, and most preferably 3 or less. Examples of the fluorine-containing alkylene group include -CF2-, -CH2CF2-, -CF2CF2-, -CF2CF2CF2-, -CF2CH2-, -CF2CF2CH2-, -CF(CF3)-, -CF(CF3)CF2-, and -CF(CF3)CH2-. The fluorine-containing alkylene group is preferably a perfluoroalkylene group. When a is 1, the fluorine-containing alkylene group is preferably a branched perfluoroalkylene group, and when a is 0, the fluorine-containing alkylene group is preferably an unbranched linear perfluoroalkylene group.

[0129] The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 3 or more. The number of carbon atoms of the fluorine-containing alkylene group having an ether bond is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, particularly preferably 9 or less, and most preferably 6 or less. The fluorine-containing alkylene group having an ether bond is, for example, a group represented by the general formula: [ka] (In the formula, Z 1 is F or CF3;Z 2 and Z 3 are H or F;Z respectively 4 is also preferably a divalent group represented by the formula: H, F, or CF3; p1+q1+r1 is an integer of 1 to 10; s1 is 0 or 1; and t1 is an integer of 0 to 5).

[0130] Specific examples of the fluorine-containing alkylene group having an ether bond include: -CF2CF(CF3)OCF2CF2-, -CF(CF3)CF2-O-CF(CF3)-, -(CF(CF3)CF2-O) n -CF(CF3)- (wherein n is an integer of 1 to 10), -CF(CF3)CF2-O-CF(CF3)CH2-, -(CF(CF3)CF2-O) nExamples include -CF(CF3)CH2- (wherein n is an integer of 1 to 10), -CH2CF2CF2O-CH2CF2CH2-, -CF2CF2CF2O-CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2-, -CF2CF2CF2O-CF2CF2CH2-, -CF2CF2O-CF2-, -CF2CF2O-CF2CH2-, etc. The fluorine-containing alkylene group having an ether bond is preferably a perfluoroalkylene group.

[0131] The carbon number of the fluorine-containing alkylene group having a keto group is preferably 3 or more. The carbon number of the fluorine-containing alkylene group having a keto group is preferably 60 or less, more preferably 30 or less, even more preferably 12 or less, and particularly preferably 5 or less.

[0132] Specific examples of fluorine-containing alkylene groups having a keto group include -CFCF(CF)CO-CF-, -CFCF(CF)CO-CFCF-, -CFCF(CF)CO-CFCFCF-, -CFCF(CF)CO-CFCFCFCF-, -CFCF(CF)CO-CFCFCFCF-, etc. The fluorine-containing alkylene group having a keto group is preferably a perfluoroalkylene group.

[0133] Water may be added to the keto group in the fluorine-containing alkylene group. Therefore, the monomer (α) may be a hydrate. Examples of the fluorine-containing alkylene group in which water is added to the keto group include -CFCF(CF)C(OH)-CF-, -CFCF(CF)C(OH)-CFCF-, -CFCF(CF)C(OH)-CFCFCF-, and -CFCF(CF)C(OH)-CFCFCFCF-.

[0134] In the formula, A is -COOM, -SO3M, -OSO3M or -C(CF3)2OM. As A, -COOM or -SO3M is preferable, and -SO3M is more preferable.

[0135] M is H, metal atom, NR 74. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 7 is H or an organic group.

[0136] Examples of the metal atom include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferred.

[0137] M is H, a metal atom, or NR 7 4 is preferred, H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, H, Na, K or NH4 is even more preferred, and H, Na or NH4 is most preferred.

[0138] As for CF2=CF-O-Rf-A (formula 1a), For example, CF2=CFOCF2COOM, CF2=CFOCF2CF2COOM, CF2=CFO(CF2)3COOM, CF2=CFOCF2CF2SO3M, CF2=CFOCF2SO3M, CF2=CFOCF2CF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M (wherein M represents H, NH4 or an alkali metal). Among them, CF2=CFOCF2COOM, CF2=CFOCF2CF2COOM, CF2=CFO(CF2)3COOM, CF2=CFOCF2CF2SO3M, CF2=CFOCF2SO3M, CF2=CFOCF2CF2CF2SO3M, CH2=CFCF2OCF(CF3)COOM (wherein M represents H, NH4 or an alkali metal.) is preferred.

[0139] CH2=CF-CF2-O-Rf-A (Equation 2a) As for

[0140] [ka] The following are preferred examples.

[0141] Among them

[0142] [ka]

[0143] It is preferable that:

[0144] As the monomer represented by general formula (2a), it is preferable that A in formula (2a) is -COOM, and in particular, at least one selected from the group consisting of CH2=CFCF2OCF(CF3)COOM and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM (wherein M is as defined above) is preferred, with CH2=CFCF2OCF(CF3)COOM being more preferred.

[0145] The monomer (α) may be copolymerized with other monomers. That is, the fluoropolymer (α) may be a homopolymer of the monomer represented by the general formula (α) or a copolymer with other monomers. The fluoropolymer (α) may also contain polymerization units (α) based on two or more different monomers represented by the general formula (α).

[0146] Preferred other monomers are those represented by the general formula CFR=CR2 (wherein R is independently H, F, or a perfluoroalkyl group having 1 to 4 carbon atoms). Preferred other monomers are fluorine-containing ethylenic monomers having 2 or 3 carbon atoms. Examples of such other monomers include CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E-isomer), and CHF=CHCF3 (Z-isomer).

[0147] As the other monomer, at least one selected from the group consisting of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CF2=CFCl) and hexafluoropropylene (CF2=CFCF3) is preferred, with tetrafluoroethylene being more preferred, due to its good copolymerizability. Therefore, the polymerized units based on the other monomer are preferably polymerized units based on tetrafluoroethylene. The polymerized units based on the other monomer may be the same or different in each occurrence, and the fluoropolymer may contain polymerized units based on two or more different other monomers.

[0148] Other monomers include those represented by the general formula (n1-2):

[0149] [ka]

[0150] (In the formula, X 1 , X 2 are the same or different H or F;X 3 is H, F, Cl, CH3 or CF3; X 4 , X 5 are the same or different and are H or F; a and c are the same or different and are 0 or 1. Rf 3 is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having 2 to 100 carbon atoms and having an ether bond).

[0151] Specifically, CH2=CFCF2-O-Rf 3 , CF2=CF-O-Rf 3 , CF2=CFCF2-O-Rf 3 , CF2=CF-Rf 3 , CH2=CH-Rf 3 , CH2=CH-O-Rf 3 (In the formula, Rf 3 is the same as formula (n1-2)).

[0152] The content of the polymerized units (β) in the fluoropolymer (β) is, in order of preference, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, and 99 mol% or more relative to all polymerized units constituting the fluoropolymer (β). The content of the polymerized units (β) is particularly preferably substantially 100 mol%, and the fluoropolymer (β) is most preferably composed only of the polymerized units (β). The higher the content of the polymerized units (β) in the fluoropolymer (β), the more advantageously the fluoropolymer (β) will have higher water solubility.

[0153] In the fluoropolymer (β), the content of polymerized units based on other monomers copolymerizable with the monomer (β) is, in order of preference, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, and 1 mol% or less, based on all polymerized units constituting the fluoropolymer (β). It is particularly preferred that the content of polymerized units based on other monomers copolymerizable with the monomer (β) is substantially 0 mol%, and it is most preferred that the fluoropolymer (β) does not contain polymerized units based on other monomers.

[0154] The lower limit of the weight average molecular weight (Mw) of the fluoropolymer (β) is, in order of preference, 1.4 × 10 4 That's 1.7 x 10 4 That's it, 1.9 x 10 4 That's it, 2.1 x 10 4 That's it, 2.3 x 10 4 That's it, 2.7 x 10 4 That's it, 3.1 x 10 4 That's it, 3.5 x 104 That's it, 3.9 x 10 4 That's it, 4.3 x 10 4 That's it, 4.7 x 10 4 That's it, 5.1 x 10 4 The upper limit of the weight average molecular weight (Mw) of the fluoropolymer is, in order of preference, 150.0×10 4 Below, 100.0 x 10 4 Below, 60.0 x 10 4 Below, 50.0 x 10 4 The following is the result.

[0155] The lower limit of the number average molecular weight (Mn) of the fluoropolymer (β) is, in order of preference, 0.7×10 4 That's 0.9 x 10 4 That's it, 1.0 x 10 4 That's it, 1.2 x 10 4 That's it, 1.4 x 10 4 That's it, 1.6 x 10 4 That's it, 1.8 x 10 4 The upper limit of the number average molecular weight (Mn) of the fluoropolymer is, in order of preference, 75.0×10 4 Below, 50.0 x 10 4 Below, 40.0 x 10 4 Below, 30.0 x 10 4 , 20.0×10 4 The following is the result.

[0156] The molecular weight distribution (Mw / Mn) of the fluoropolymer (β) is preferably 3.0 or less, more preferably 2.4 or less, even more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.9 or less.

[0157] The fluoropolymer (β) usually has end groups. The end groups are end groups generated during polymerization, and representative end groups are independently selected from hydrogen, iodine, bromine, linear or branched alkyl groups, and linear or branched fluoroalkyl groups, and may optionally contain at least one catenary heteroatom. The alkyl or fluoroalkyl group preferably has 1 to 20 carbon atoms. These end groups are generally generated from the initiator or chain transfer agent used to form the fluoropolymer (β), or are generated during the chain transfer reaction.

[0158] The fluorine-containing particle dispersion stabilizer also includes anionic fluorine-containing surfactants, such as those represented by formula (1): Rf§(X - ) j (M + ) j Formula (1) (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X - -COO - , -PO3 - , or -SO3 - and M + is H + , NH4 + , an alkali metal ion, and j may be 1 or 2).

[0159] Specific examples of the anionic fluorine-containing surfactant include ammonium (per)fluoro(oxy)carboxylate, ammonium sodium (per)fluoro(oxy)carboxylate, and (per)fluoropolyoxyalkylene having one or more carboxyl terminal groups.

[0160] Examples of fluorinated surfactants, in particular (per)fluorooxyalkylene surfactants, are described in particular in US Patent Application Publication No. 2007 / 015864 (3M INNOVATIVE PROPERTIES) 8 / 01 / 2007, US Patent Application Publication No. 2007 / 015865 (3M INNOVATIVE PROPERTIES) 18 / 01 / 2007, US Patent Application Publication No. 2007 / 015866 (3M INNOVATIVE PROPERTIES) 18 / 01 / 2007, and US Patent Application Publication No. 2007 / 025902 (3M INNOVATIVE PROPERTIES) 1 / 02 / 2007.

[0161] The fluorine-containing particle dispersion stabilizer may also be a fluorine-containing surfactant in which the molecular weight of the anionic moiety is 800 or less. The "anionic portion" means the portion of the anionic fluorine-containing surfactant excluding the cation. - )j" part.

[0162] Of the particle dispersion stabilizers described above, fluorine-containing particle dispersion stabilizers are preferred, and among these, fluoropolymers of monomers represented by the following formula are listed: In the following formula, M represents H, NH4, or an alkali metal. CF2=CFOCF2COOM, CF2=CFOCF2CF2COOM, CF2=CFO(CF2)3COOM, CF2=CFOCF2CF2SO3M, CF2=CFOCF2SO3M, CF2=CFOCF2CF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2COOM, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOM, CF2=CFOCF2CF(CF3)OCF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2SO3M, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO3M, CH2=CF-CF2-OCF(CF3)COOM, CH2=CF-CF2-OCF(CF3)SO3M, CH2=CF-CF2-OCF(CF3)CF2OCF(CF3)COOM, CH2=CF-CF2-O(CF(CF3)CF2O)2CF(CF3)COOM, CH2=CF-CF2-OCF(CF3)CF2OCF(CF3)SO3M, CH2=CF-CF2-O(CF(CF3)CF2O)2CF(CF3)SO3M.

[0163] The monomers are particularly preferably CF2=CFOCF2COOM, CF2=CFOCF2CF2COOM, CF2=CFO(CF2)3COOM, CF2=CFOCF2CF2SO3M, CF2=CFOCF2SO3M, CF2=CFOCF2CF2CF2SO3M, CH2=CFCF2OCF(CF3)COOM, and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM.

[0164] As the particle dispersion stabilizer, it is preferable to use at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of fluoropolymer (α) of monomer (α) represented by general formula (α) and anionic fluorine-containing surfactants represented by general formula (1), and it is more preferable to use the fluorine-containing particle dispersion stabilizer in combination with at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer. The fluorine-containing particle dispersion stabilizer is preferably a fluoropolymer (α), more preferably a fluoropolymer (α) of a monomer represented by formula 1a: CF2=CF-O-Rf-A. The polymer dispersion stabilizer is preferably polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, or polymethacrylic acid, and more preferably polyvinyl alcohol.

[0165] The content of the particle dispersion stabilizer is preferably 0.0001 to 10 parts by mass, and more preferably 0.005 to 5 parts by mass, relative to 100 parts by mass of the solution.

[0166] In step A, the solution preferably contains a small amount of the phase separation promoter. This improves the electrical properties. The content of the phase separation promoter is preferably 0.005 parts by mass or less, more preferably 0.001 parts by mass or less, per part by mass of the solution. The lower limit is not particularly limited, and may be 0 parts by mass.

[0167] Step A is a step of dispersing a solution containing a perfluoromonomer and a non-polymerizable solvent, as well as a monomer copolymerizable with the perfluoromonomer, an initiator, a dispersion stabilizer, and the like, which are used as needed, in water to obtain a dispersion. As a dispersion method, various known methods can be used, such as dispersion methods that use mechanical shear force, such as a homogenizer or membrane emulsification method. The temperature condition during dispersion may be 0°C or higher but lower than 100°C, preferably 0 to 90°C. If the solution in the dispersion step contains an initiator, the temperature must be below a temperature that would affect the decomposition of the initiator used, and is usually around room temperature or lower, particularly preferably about 0 to 30°C.

[0168] In step A, the droplets formed by dispersing the solution are usually not monodisperse, but generally contain a mixture of droplets with various different particle sizes. Therefore, the hollow microparticles finally obtained also have different particle sizes. By selecting a suitable dispersion method, it is possible to obtain monodispersed droplets with uniform droplet size. For example, a method for producing monodispersed droplets using a membrane emulsification method using porous glass (SPG) can be used. When such monodispersed droplets with uniform particle size are prepared, the resulting hollow microparticles will also be monodispersed with uniform particle size. In either case, the average particle size of the droplets may be appropriately determined depending on the desired average particle size of the hollow fine particles.

[0169] Step A is also preferably Step A-1, in which the solution is dispersed in water at a temperature of 50°C or higher (preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher) to obtain a dispersion, or Step A-2, in which the solution is dispersed in water at a temperature below 50°C to obtain a dispersion, and the obtained dispersion is heated to a temperature of 50°C or higher (preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher). In both steps A-1 and A-2, the upper limit temperature is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower. By employing these steps, even if a perfluoromonomer is used, the dispersion is less likely to undergo phase separation, and polymerization can proceed efficiently.

[0170] In the manufacturing method of the present disclosure, it is preferable to use a polymerization initiator. The polymerization initiator may be added to the solution before step A, or may be added to the dispersion liquid after the dispersion step of step A and before step B. However, when the dispersion step is performed at a relatively high temperature (for example, 50°C or higher) as described above, if a polymerization initiator is added to the solution before step A, polymerization may start during the dispersion step. Therefore, it is preferable to add the polymerization initiator to the dispersion liquid after the dispersion step of step A and before step B. This makes it possible to perform the dispersion step of step A at a relatively high temperature.

[0171] The polymerization initiator initiates the polymerization of the monomer in droplets formed by dispersing the solution in water, and can be any conventional initiator, such as an oil-soluble initiator. Examples include radical polymerization initiators such as azo compounds, such as azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis(N-butyl-2-methylpropionamide); and peroxides, such as cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, and lauroyl peroxide. Alternatively, a photopolymerization initiator that initiates polymerization by light such as ultraviolet light may be used. Such a photopolymerization initiator is not particularly limited, and any conventionally used initiator may be used.

[0172] The azo compound is preferably at least one selected from the group consisting of 2,2'-azobis(methyl isobutyrate), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and azobisisobutyronitrile, and more preferably 2,2'-azobis(methyl isobutyrate).

[0173] Examples of the polymerization initiator include compounds represented by the following formulae (C1), (C2), and (C3) (hereinafter, these may be referred to as "compound (C1)," "compound (C2)," and "compound (C3)," respectively), and inorganic peroxides. Compounds (C1) to (C3) and inorganic peroxides may be used alone or in combination. [ka] [In the formula, R 31 and R 32 are the same or different and are a group in which at least one fluorine atom in a C3-C10 perfluoroalkyl group which may be substituted with a perfluorophenyl is substituted with a hydrogen atom, or a group in which at least one fluorine atom in a perfluorophenyl which may be substituted with a linear or branched C1-C4 perfluoroalkyl group is substituted with a hydrogen atom. [ka] [In the formula, R 33 and R 34 are the same or different and are a group in which at least one fluorine atom in a C3-C10 perfluoroalkyl group which may be substituted with a perfluorophenyl is substituted with a hydrogen atom, or a group in which at least one fluorine atom in a perfluorophenyl which may be substituted with a linear or branched C1-C4 perfluoroalkyl group is substituted with a hydrogen atom], and Formula (C3): [ka] [In the formula, R 35 and R 36 are the same or different and are a group in which at least one fluorine atom in a C1-C10 perfluoroalkyl group which may be substituted with a perfluorophenyl is substituted with a hydrogen atom, or a group in which at least one fluorine atom in a perfluorophenyl which may be substituted with a linear or branched C1-C4 perfluoroalkyl group is substituted with a hydrogen atom.

[0174] R31 and R 32 are preferably the same or different and are perfluoropropyl, perfluoroisopropyl, perfluoro2-phenyl-2-propyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro2-methyl-2-pentyl, perfluoro2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro2-methylhexyl, perfluoro2-ethylhexyl, perfluorocyclohexyl, perfluoro4-methylcyclohexyl, perfluoro4-ethylcyclohexyl, perfluoro4-tertbutylcyclohexyl, perfluoroheptyl, perfluoro2-heptyl, perfluoro3-heptyl, perfluorooctyl, perfluoro2-methyl-2-octyl, perfluorononyl, perfluorodecyl, perfluorophenyl, perfluoro2-methylphenyl, perfluoro3-methylphenyl, or perfluoro4-methylphenyl, in which at least one fluorine atom has been substituted with a hydrogen atom.

[0175] R 31 and R 32 In the formula, the number of fluorine atoms substituted for hydrogen atoms is 1 to the maximum substitutable number, preferably 3 less than the maximum substitutable number to the maximum substitutable number, more preferably 2 less than the maximum substitutable number to the maximum substitutable number, even more preferably 1 less than the maximum substitutable number to the maximum substitutable number, and particularly preferably the maximum substitutable number. R 31 and R 32 are more preferably the same or different and are propyl, isopropyl, sec-butyl, 2-ethylhexyl, or 4-tert-butylcyclohexyl. R 31 and R 32 are particularly preferably the same or different and are propyl or isopropyl.

[0176] Preferred examples of the compound (C1) include di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate. Particularly preferred compounds (C1) are di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate.

[0177] R 33 and R 34 are preferably the same or different and are perfluoropropyl, perfluoroisopropyl, perfluoro2-phenyl-2-propyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro2-methyl-2-pentyl, perfluoro2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro2-methylhexyl, perfluoro2-ethylhexyl, perfluorocyclohexyl, perfluoro4-methylcyclohexyl, perfluoro4-ethylcyclohexyl, perfluoro4-tertbutylcyclohexyl, perfluoroheptyl, perfluoro2-heptyl, perfluoro3-heptyl, perfluorooctyl, perfluoro2-methyl-2-octyl, perfluorononyl, perfluorodecyl, perfluorophenyl, perfluoro2-methylphenyl, perfluoro3-methylphenyl, or perfluoro4-methylphenyl, in which at least one fluorine atom has been substituted with a hydrogen atom.

[0178] R 33 and R 34 In the formula, the number of fluorine atoms substituted for hydrogen atoms is 1 to the maximum substitutable number, preferably 3 less than the maximum substitutable number to the maximum substitutable number, more preferably 2 less than the maximum substitutable number to the maximum substitutable number, and even more preferably 1 less than the maximum substitutable number to the maximum substitutable number. R33 and R 34 are more preferably the same or different and are isopropyl, 2,4,4-trimethylpentyl, ω-hydro-dodecafluorohexyl, ω-hydro-hexadecafluorooctyl, phenyl, or 3-methylphenyl.

[0179] Preferred examples of compound (C2) include diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl peroxide, benzoyl peroxide, benzoyl-m-methylbenzoyl peroxide, and m-toluoyl peroxide. Particularly preferred compounds (C2) are diisobutyryl peroxide, di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl peroxide, and benzoyl peroxide.

[0180] R 35 and R 36are preferably the same or different and are each a group in which at least one fluorine atom has been substituted with a hydrogen atom, such as perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluoro2-phenyl-2-propyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro2-methyl-2-pentyl, perfluoro2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro2- perfluorooctyl, perfluorononyl, perfluorodecyl, perfluorophenyl ...

[0181] R 35 and R 36 In the formula, the number of fluorine atoms substituted for hydrogen atoms is 1 to the maximum substitutable number, preferably 3 less than the maximum substitutable number to the maximum substitutable number, more preferably 2 less than the maximum substitutable number to the maximum substitutable number, even more preferably 1 less than the maximum substitutable number to the maximum substitutable number, and particularly preferably the maximum substitutable number. R 35 and R 36 are more preferably the same or different and are isopropyl, 2-phenyl-2-propyl, tert-butyl, 2-methyl-2-pentyl, 2,4,4-trimethyl-2-pentyl, 2-heptyl, 2-methyl-2-octyl, phenyl, or 3-methylphenyl.

[0182] Preferred examples of the compound (C3) include tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-hexyl peroxypivalate, OO-tert-butyl O-isopropyl peroxycarbonate, and tert-butyl peroxyacetate. Particularly preferred compounds (C3) are tert-butyl peroxypivalate and tert-hexyl peroxypivalate.

[0183] Preferred examples of inorganic peroxides include ammonium, sodium and potassium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, percarbonate and permanganate. Particularly preferred inorganic peroxides are ammonium persulfate, sodium persulfate, and potassium persulfate. The inorganic peroxides may be used alone or in combination of two or more kinds. The inorganic peroxides may also be used in combination with reducing agents such as sulfite reducing agents (e.g., sodium dithionite) and sulfite reducing agents (e.g., sodium sulfite, ammonium sulfite, and sodium hydrogen sulfite).

[0184] Particularly preferred polymerization initiators include initiators having an ester group at the end. By introducing the ester group of the initiator into the end of the polymer (perfluororesin), the hydrophilicity of the polymer is further improved.

[0185] In the initiator, the ester group may be present at one terminal, but is preferably present at both terminals. The ester group is preferably a group represented by -COOR (R is an unbranched alkyl group). The alkyl group represented by R is preferably a C1 to C5 alkyl group, more preferably a C1 to C3 alkyl group, and even more preferably a methyl group.

[0186] Examples of the initiator include an azo compound having an ester group at its terminal and a peroxide having an ester group at its terminal.

[0187] The initiator preferably does not contain a fluorine atom or an aromatic ring.

[0188] The amount of the initiator used may be adjusted appropriately depending on the type of the target perfluororesin, etc., but is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, based on the total amount of the monomers used.

[0189] Step B is a step of polymerizing a perfluoromonomer to obtain phase-separated microparticles containing a perfluororesin. Step B may be a step of polymerizing at least a perfluoromonomer, and may be a step of polymerizing only a perfluoromonomer, or a step of polymerizing a perfluoromonomer and the above-mentioned monomer copolymerizable with the perfluoromonomer.

[0190] The polymerization in step B can be carried out by a method similar to a conventionally known polymerization method such as microemulsion polymerization, miniemulsion polymerization, or microsuspension polymerization. The polymerization in step B may be suspension polymerization. In order to subject the dispersion in which the solution is dispersed to suspension polymerization, the dispersion may be heated while being stirred.

[0191] The polymerization temperature is not particularly limited as long as it is a temperature sufficient to initiate polymerization of the perfluoromonomer (and a monomer copolymerizable with the perfluoromonomer, which is used as needed) with the initiator, but is generally 10 to 90°C, preferably 30 to 80°C, and more preferably 30 to 75°C.

[0192] The polymerization is continued until the desired hollow microparticles are obtained. The time required for the polymerization varies depending on the types of the fluorine-containing monomer (and, if necessary, a monomer copolymerizable with the fluorine-containing monomer), polymerization initiator, and non-polymerizable solvent used, but is generally about 3 to 24 hours.

[0193] The polymerization is preferably carried out in an atmosphere of an inert gas such as nitrogen gas or argon.

[0194] By carrying out the polymerization in this manner, the perfluoromonomer (or the monomer copolymerizable with the perfluoromonomer and the fluorine-containing monomer) is polymerized in the droplets of the solution. The phase separation of the obtained polymer (phase-separated microparticles) is promoted by the presence of the non-polymerizable solvent, and the resulting polymer (phase-separated microparticles) has a single-layer shell and a core portion encapsulating the non-polymerizable solvent. The shell portion of the phase-separated microparticles is composed of a perfluororesin containing polymerized units based on a perfluoromonomer (or polymerized units based on a perfluoromonomer and a monomer copolymerizable with the perfluoromonomer).

[0195] The glass transition temperature of the perfluororesin is preferably 60° C. or higher, more preferably 120° C. or higher, since high strength and high hardness can be expected. In the present disclosure, the glass transition temperature (Tg) can be determined by using a DSC (differential scanning calorimeter: DSC7000 manufactured by Hitachi High-Tech Science Corporation) to increase the temperature (first run), decrease the temperature, and increase the temperature again (second run) in the temperature range from 30°C to 200°C at a rate of 10°C / min, and by determining the glass transition temperature (Tg) as the midpoint of the endothermic curve in the second run.

[0196] The perfluororesin may consist solely of polymerized units based on a perfluoromonomer, or may contain polymerized units based on a perfluoromonomer and polymerized units based on a monomer copolymerizable with the perfluoromonomer. The perfluoromonomer and the monomer copolymerizable with the perfluoromonomer are the same as those explained in the production method of the present disclosure above.

[0197] In the perfluororesin, the polymerized units based on perfluoromonomers preferably account for 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, of the total polymerized units. The upper limit is not particularly limited and may be 100% by mass. When the polymerized units based on perfluoromonomers are in the above range, the electrical properties of the resulting hollow microparticles become good.

[0198] The perfluororesin preferably contains polymerized units based on a perfluoromonomer corresponding to a monofunctional monomer and polymerized units based on a polyfunctional monomer (crosslinkable monomer), which strengthens the shell of the hollow microparticles, thereby reducing the shell thickness and increasing the porosity. The polyfunctional monomer may be a perfluoromonomer, a fluorine-containing monomer other than a perfluoromonomer, or a non-fluorine-containing monomer, but a perfluoromonomer is preferred. That is, the perfluororesin preferably contains polymerization units based on a perfluoromonomer corresponding to a monofunctional monomer and polymerization units based on a perfluoromonomer corresponding to a polyfunctional monomer (particularly, a perfluoromonomer represented by formula (b)). This makes the shell of the hollow microparticle stronger and enables the realization of high electrical properties.

[0199] In the perfluororesin, the polymerized units based on polyfunctional monomers (crosslinkable monomers) preferably account for 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more of the total polymerized units. Also, the polymerized units based on crosslinkable monomers are preferably 70% by mass or less, more preferably 65% by mass or less, and even more preferably 55% by mass or less. By ensuring that the polymerized units based on crosslinkable monomers are within the above range, the resulting hollow microparticles can have excellent strength and electrical properties.

[0200] In the perfluororesin, the polymerized units based on non-fluorine-containing monomers preferably account for 0 to 70 mass % of all polymerized units, and more preferably 0 to 50 mass %.

[0201] In the perfluororesin, the polymerized units based on fluorine-containing monomers other than perfluoromonomers preferably account for 0 to 70 mass %, more preferably 0 to 50 mass %, of all polymerized units.

[0202] The perfluororesin preferably contains a particle dispersion stabilizer. The content of the particle dispersion stabilizer is, for example, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, relative to the perfluororesin. Also, it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. When within the above range, dispersion stability in water is increased, resulting in excellent storage stability. The particle dispersion stabilizer is the same as that described in the production method of the present disclosure above.

[0203] The perfluororesin preferably has a fluorine content of 10% by mass or more. A fluorine content of 10% by mass or more improves electrical properties and water resistance. The fluorine content is more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 50% by mass or more. Hollow microparticles containing such perfluororesin can be obtained by the production method of the present disclosure described above, particularly by a production method in which step A is step A-1 or step A-2.

[0204] In the perfluororesin, the mass ratio (C / E) of the polymerized units (C) based on a monofunctional perfluoromonomer (perfluoroolefin) to the polymerized units (E) based on a polyfunctional perfluoromonomer (perfluoroolefin) is preferably 75 / 25 to 25 / 75, more preferably 70 / 30 to 30 / 70, and even more preferably 60 / 40 to 40 / 60. When a polyfunctional monomer other than a perfluoromonomer is used, the amount of polymerized units based on the monomer is included in (E). In this case, the preferred mass ratio is the same as above.

[0205] The perfluororesin preferably has a relative dielectric constant (1 kHz) of 5.0 or less. The relative dielectric constant is more preferably 4.0 or less, even more preferably 3.7 or less, and particularly preferably 3.5 or less. The lower limit of the relative dielectric constant is not particularly limited, but may be, for example, 1.1 or more. In the present disclosure, the relative dielectric constant is a value determined by a measurement method in accordance with JIS C 2138.

[0206] The refractive index of the perfluororesin is preferably 1.40 or less, more preferably 1.39 or less, and particularly preferably 1.38 or less. The lower limit of the refractive index is not particularly limited, but may be, for example, 1.30 or more, and is preferably 1.35 or more from the viewpoint of solubility in non-polymerizable solvents. The refractive index is a value determined by the critical angle method.

[0207] Step C is a step of removing the non-polymerizable solvent from the phase-separated fine particles to obtain hollow fine particles. By step C, hollow fine particles substantially free of non-polymerizable solvent are obtained. The method for removing the non-polymerizable solvent is not particularly limited, but examples thereof include heat treatment, reduced pressure treatment, natural drying, freeze-drying, etc. Heat treatment is preferred from the standpoint of simplicity and economy. Freeze-drying is also preferred, as it is easier to maintain the hollow structure. The conditions for the heat treatment may be appropriately set depending on the type and amount of the non-polymerizable solvent, but heating is preferably performed under conditions of a temperature of 20 to 300°C and a pressure of about 1 to 100,000 Pa.

[0208] The manufacturing method of the present disclosure can produce hollow microparticles with large particle diameters by steps A to C. The average particle diameter of the hollow microparticles is preferably 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 5.0 μm or more. From the viewpoint of particle stability, the average particle diameter is preferably 50.0 μm or less, and more preferably 30.0 μm or less. In the present disclosure, the average particle size can be measured by DLS (dynamic light scattering) or calculated from an optical microscope photograph using particle size analysis software LUZEX AP. In this case, it is desirable to take and analyze multiple photographs so that the total number of particles is 50 or more.

[0209] The hollow microparticles obtained by the production method of the present disclosure have a single-pore structure consisting of a shell containing a perfluororesin and a hollow portion. In the present disclosure, the term "single-pore structure" refers to a structure having only one closed void, excluding structures having multiple voids such as porous structures. In the following description, the portion of the hollow microparticle other than the voids will be referred to as the "shell."

[0210] In the hollow microparticles, the pore size of the hollow portion is preferably 66% or more, more preferably 74% or more, and even more preferably 79% or more of the diameter of the hollow microparticles, and is preferably 95% or less, more preferably 93% or less, even more preferably 90% or less, and particularly preferably 88% or less. In the present disclosure, the pore size of the hollow portion can be calculated by image analysis of a TEM photograph of the hollow microparticles using particle size analysis software LUZEX AP. Specifically, approximately 200 hollow microparticles are randomly selected from the TEM photograph, and the inner radius (R1) is measured, allowing the pore size of the hollow portion to be calculated using the following formula: Hollow hole diameter = R1 x 2

[0211] The ratio of the shell thickness to the diameter of the hollow particles is preferably 17% or less, more preferably 13% or less, even more preferably 10% or less, and particularly preferably 9% or less. A thinner shell results in a higher porosity, allowing hollow particles to have a lower dielectric constant. From the viewpoint of the strength of the hollow fine particles, the above ratio is preferably 4% or more, and more preferably 6% or more. In the present disclosure, the shell thickness can be calculated by image analysis of an optical microscope photograph or a TEM photograph of the hollow microparticles using particle size analysis software LUZEX AP. Specifically, approximately 50 to 200 hollow microparticles are randomly selected from the optical microscope photograph or the TEM photograph, and the inner radius (R1) and outer radius (R2) are measured, allowing the shell thickness to be calculated using the following formula: Shell thickness = R2-R1

[0212] The porosity of the hollow fine particles is preferably 30% by volume or more, more preferably 40% by volume or more, even more preferably 50% by volume or more, and particularly preferably 55% by volume or more. A high porosity can lower the relative dielectric constant of the hollow fine particles, making them suitable for use as electrical materials. There are no particular restrictions on the upper limit of the porosity, but from the viewpoint of strength, it is preferably 80% by volume or less, more preferably 70% by volume or less. In the present disclosure, the porosity was calculated by the following formula. Porosity M (volume %) = amount of non-polymerizable solvent (g) / (amount of perfluoromonomer (g) + amount of crosslinkable monomer (g) + amount of non-polymerizable solvent (g)) × 100

[0213] The refractive index of the hollow fine particles is preferably 1.40 or less, more preferably 1.35 or less, even more preferably 1.30 or less, and particularly preferably 1.25 or less. The lower limit of the refractive index is not particularly limited, but may be, for example, 1.10 or more. In the present disclosure, the refractive index is a value determined by the critical angle method.

[0214] When a phase separation promoter is used, the phase separation promoter is contained in the shell of the hollow microparticles, but from the viewpoint of electrical properties, it is preferable that the hollow microparticles contain a small amount of phase separation promoter. Therefore, in the production method of the present disclosure, it is preferable to use as little phase separation promoter as possible. In the hollow microparticles, the content of the phase separation promoter is, for example, preferably 5% by mass or less, more preferably 1% by mass or less, and preferably 0.1% by mass or less, relative to the perfluororesin. The lower limit is not particularly limited, and may be 0% by mass.

[0215] From the viewpoint of low dielectric properties and low refractive index, the hollow portions of the hollow fine particles are preferably filled with a gas, more preferably air.

[0216] (Hollow fine particles) The hollow microparticles of the present disclosure can be obtained by the manufacturing method of the present disclosure. The preferred embodiments described in the manufacturing method of the present disclosure can also be applied to the hollow microparticles of the present disclosure. Furthermore, the production method of the present disclosure makes it possible to obtain hollow microparticles that maintain their particle shape even when isolated.

[0217] The hollow microparticles of the present disclosure contain a perfluororesin containing polymerized units based on a perfluoromonomer, are substantially free of non-polymerizable solvents, have an average particle size of 1.0 μm or more, and have a single-pore structure.

[0218] The particle size of the hollow microparticles of the present disclosure can be adjusted by changing the droplet size in the manufacturing method of the present disclosure described above, but it has been difficult to increase the average particle size of hollow microparticles containing perfluororesin using conventional methods. By using the manufacturing method of the present disclosure described above, it is possible to increase the average particle size of hollow microparticles containing perfluororesin, and it is possible to manufacture hollow microparticles having an average particle size of 1.0 μm or more.

[0219] The hollow microparticles of the present disclosure are substantially free of non-polymerizable solvents. Here, "substantially free of non-polymerizable solvents" means that the non-polymerizable solvent content is 0.1% by mass or less relative to the hollow microparticles. The hollow microparticles of the present disclosure may be completely free of non-polymerizable solvents.

[0220] The hollow microparticles of the present disclosure have an average particle size of 1.0 μm or more, preferably 2.0 μm or more, and more preferably 5.0 μm or more, and preferably 50.0 μm or less, more preferably 40.0 μm or less, and even more preferably 30.0 μm or less.

[0221] The hollow fine particles of the present disclosure have a hollow and single-pore structure, which gives them excellent low dielectric properties and high-frequency characteristics, making them suitable for use as electronic materials. That is, the hollow fine particles of the present disclosure are preferably used as electronic materials. Furthermore, if a hollow microparticle has a porous structure, when it is used as an additive, the matrix resin penetrates into the pores, significantly reducing the hollowness, and the desired electrical properties may not be obtained. In contrast, the hollow microparticles of the present disclosure have a single-pore structure, which makes them less susceptible to such problems and has the advantage of being easy to adjust to the desired electrical properties.

[0222] Furthermore, the hollow microparticles of the present disclosure contain a perfluororesin and have an average particle size of 1.0 μm or more, which provides excellent low dielectric properties and reduces the surface area when used at the same volume. From this perspective, they are suitable for use as electronic materials. A small average particle size increases the specific surface area, which can significantly reduce electrical properties due to the influence of moisture adhering to the interface.

[0223] (phase separated fine particles) By carrying out steps A and B in the manufacturing method of the present disclosure, an aqueous dispersion containing the phase-separated microparticles of the present disclosure (aqueous dispersion of the present disclosure) can be obtained. The phase-separated microparticles of the present disclosure may be used as the aqueous dispersion itself, or may be used in the form of a powder after filtering and washing with water as necessary. The preferred forms described in the manufacturing method of the present disclosure can also be applied to the phase-separated microparticles of the present disclosure.

[0224] The phase-separated fine particles of the present disclosure contain a perfluororesin containing polymerized units based on a perfluoromonomer and a non-polymerizable solvent, have an average particle size of 1.0 μm or more, and have a single-pore structure.

[0225] The phase-separated microparticles of the present disclosure differ from hollow microparticles of the present disclosure in that they contain a non-polymerizable solvent in the hollow portion. The content of the non-polymerizable solvent is preferably 10% by mass or more, more preferably 30% by mass or more, based on the weight of the phase-separated microparticles. The content of the non-polymerizable solvent is preferably 70% by mass or less, more preferably 60% by mass or less, based on the weight of the phase-separated microparticles.

[0226] The phase-separated microparticles of the present disclosure have an average particle size of 1.0 μm or more, preferably 2.0 μm or more, and more preferably 5.0 μm or more, and preferably 50.0 μm or less, more preferably 40.0 μm or less, and even more preferably 30.0 μm or less.

[0227] The phase-separated fine particles of the present disclosure are suitable for use as electronic materials, similar to the hollow fine particles of the present disclosure. That is, the phase-separated fine particles of the present disclosure are preferably used as electronic materials.

[0228] (composition) The first composition of the present disclosure comprises the hollow particulates of the present disclosure and a perfluororesin containing polymerized units based on a perfluoromonomer.

[0229] The first composition of the present disclosure may be an intentional mixture of hollow fine particles and an insulating resin, or may be a composition produced in the process of producing hollow fine particles. In addition, the first composition of the present disclosure preferably has hollow fine particles dispersed in the insulating resin.

[0230] In the first composition of the present disclosure, the insulating resin is added separately from the perfluororesin contained in the hollow microparticles. The insulating resin is not particularly limited, and examples thereof include fluorine-containing resins, epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, silicone resins, benzoxazine resins, melamine resins, urea resins, allyl resins, phenolic resins, unsaturated polyester resins, polyurethane resins, and aniline resins. Among these, fluorine-containing resins, epoxy resins, thermosetting polyimide resins, modified polyphenylene ether resins, thermosetting polyimide resins, silicone resins, benzoxazine resins, and melamine resins are preferred. These insulating resins may be used alone or in combination of two or more. Furthermore, the insulating resin may be the same type as the perfluororesin contained in the hollow microparticles.

[0231] In the first composition of the present disclosure, the composition ratio of the insulating resin to the hollow fine particles is not limited, but may be, for example, any composition in which the mass ratio (insulating resin / hollow fine particles) is 5 / 95 to 95 / 5. Furthermore, in the first composition of the present disclosure, the content of the hollow microparticles is not particularly limited and may be appropriately set according to the properties required for each application, and may be, for example, 10 to 90 parts by mass per 100 parts by mass of the insulating resin.

[0232] The first composition of the present disclosure is preferable in that the electrical properties can be controlled.

[0233] The second composition of the present disclosure includes the phase-separated fine particles of the present disclosure and an insulating resin.

[0234] The second composition of the present disclosure may be an intentional mixture of phase-separated particles and an insulating resin, or may be a composition produced in the process of producing phase-separated particles. In addition, the second composition of the present disclosure preferably has phase-separated fine particles dispersed in the insulating resin.

[0235] In the second composition of the present disclosure, the insulating resin is added separately from the perfluororesin contained in the phase-separated fine particles, and the insulating resin may be any of those described in the first composition of the present disclosure.

[0236] In the second composition of the present disclosure, the composition ratio of the insulating resin to the phase-separated fine particles is not limited, and may be, for example, any composition in which the mass ratio (insulating resin / phase-separated fine particles) is 5 / 95 to 95 / 5. Furthermore, in the second composition of the present disclosure, the content of the phase-separated fine particles is not particularly limited and may be appropriately set according to the properties required for each application, and may be, for example, 10 to 90 parts by mass per 100 parts by mass of the insulating resin.

[0237] The second composition of the present disclosure is preferable in that the electrical properties can be controlled, similar to the first composition of the present disclosure.

[0238] The hollow fine particles, phase-separated fine particles, first composition, and second composition of the present disclosure are used for electronic material applications that are not particularly limited, and examples thereof include printed wiring boards, antenna substrates, and interlayer insulating films for high-frequency connectors, etc. They are particularly useful for high-frequency compatible substrates used in 5G and 6G. [Example]

[0239] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0240] The values in the examples were measured by the following methods.

[0241] [Average particle size] Image analysis of optical microscope photographs of the microparticles was performed using the particle size analysis software LUZEX AP. Specifically, photographs were taken at different locations, and the average particle size was calculated so that the total number of particles was 50 or more. The average particle size is the same for phase-separated microparticles and hollow microparticles.

[0242] [Porosity] The porosity was calculated using the following formula. Porosity M (volume %) = amount of non-polymerizable solvent (g) / (total amount of monomers (g) + amount of non-polymerizable solvent (g)) × 100 The porosity M is the same for the phase-separated fine particles and the hollow fine particles.

[0243] [Glass transition temperature] Using a DSC (differential scanning calorimeter: Hitachi High-Tech Science Corporation, DSC7000), the sample was heated (first run) - cooled - heated again (second run) at 10°C / min in the temperature range of 30°C or higher to 200°C or lower, and the midpoint of the endothermic curve in the second run was taken as the glass transition temperature (°C).

[0244] [Polymerization rate] After weighing, the mixture was dried at 100°C for 24 hours. The solid content ratio Z was calculated from the residue, and the polymerization rate C (%) was calculated using the following formula from the charged monomer ratio (total ratio Q of the amount of monomers to the total weight). Polymerization rate C(%) = Z / Q×100(%)

[0245] [Example 1] The monofunctional perfluoromonomer used was perfluoro(2-methylene-4-methyl-1,3-dioxolane) (monomer a7 (monomer represented by formula (a-7))), the polyfunctional perfluoromonomer used was 1,1,2,2,3,3-hexafluoro-1,3-bis[(1,2,2-trifluorovinyl)oxy]propane (PFDVE) (CF2=CF-O-(CF2)3-O-CF=CF2), and the non-polymerizable solvent used was 2,2- fluorinated alcohol. 3,3-4,4-5,5-6,6-7,7-dodecafluoro-1-heptanol (H(CF2)6CH2OH) was used; as the particle dispersion stabilizer, a homopolymer of CF2=CFCF2CF2SO3H with Mw=10,000, which is a fluorine-containing particle dispersion stabilizer, and polyvinyl alcohol (PVA) with Pn=1700 and a degree of saponification=88%, which is a polymer dispersion stabilizer; and as the polymerization initiator, 2,2'-azobis(methyl isobutyrate) (compound below) (initiator (1)), which is an azo compound having an ester group at the end. [ka]

[0246] According to the composition of Table 2 below, a crosslinkable monomer and a perfluoromonomer are added to a non-polymerizable solvent in a mass ratio of 3:2, and a polymerization initiator is dissolved in the resulting homogeneous oil phase (solution). This is then dispersed in an aqueous medium in which a particle dispersion stabilizer and a pH adjuster have been dissolved to a predetermined concentration using a homogenizer to prepare a dispersion containing suspended droplets. This is then polymerized under a nitrogen atmosphere at 70°C for 24 hours, stirring at 180 rpm, to prepare aqueous dispersed particles.

[0247] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 1. The optical microscope photograph after polymerization confirmed that particles with a hollow structure (single hole) had been obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 6.05 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0248] [Example 2] The phase-separated microparticles obtained in Example 1 were frozen at -50°C, then freeze-dried at 18 Pa at room temperature for 24 hours, and then observed with an SEM. The results are shown in Figures 2 and 3. It was confirmed that hollow microparticles with a single-pore structure were obtained. The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0249] [Example 3] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the amount of polymerization initiator used was halved.

[0250] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 4. The optical microscope photograph after polymerization confirmed that particles with a hollow structure (single hole) had been obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 2.85 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0251] [Example 4] The phase-separated microparticles obtained in Example 3 were freeze-dried under the conditions of Example 2, and then observed with an SEM. It was confirmed that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0252] [Example 5] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the amount of polymerization initiator used was reduced to 1 / 5.

[0253] In an optical microscope photograph (not shown) after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 1.60 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0254] [Example 6] The phase-separated microparticles obtained in Example 5 were freeze-dried under the conditions of Example 2 and then observed with an SEM. The results are shown in Figure 5. It was confirmed that hollow microparticles having a single-pore structure were obtained. The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0255] [Comparative Examples 1 to 3] Although a perfluoromonomer and a non-polymerizable solvent were mixed according to the composition in Table 2, the perfluoromonomer did not dissolve and could not be polymerized.

[0256] Comparative Example 4 Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2, and observed under an optical microscope. The obtained particles were not hollow, but had a structure opposite to that of Example 1, with the polymer on the inside and the oil phase on the outside (not shown).

[0257] Comparative Example 5 Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2. The particles were freeze-dried under the conditions of Example 2 and then observed with an SEM. The results are shown in Figure 6. A porous body was obtained.

[0258] Comparative Example 6 The same procedure as in Example 1 was carried out except that the composition was as shown in Table 2, but the polymerization reaction did not proceed. This is presumed to be because the polymerization initiator did not dissolve.

[0259] Comparative Example 7 Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2. After freeze-drying under the conditions of Example 2, the particles were observed with an SEM. The results are shown in Figure 7. What was obtained was an aggregate of numerous solid fine particles (a type of porous body).

[0260] [Comparative Example 8] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2. After freeze-drying under the conditions of Example 2, the particles were observed with an SEM. The results are shown in Figure 8. A porous body was obtained.

[0261] Comparative Example 9 Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2, and were observed under an optical microscope. The results are shown in Figure 9. What was obtained was an aggregate of numerous solid fine particles (a type of porous body).

[0262] [Comparative Example 10] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2, and observed under an optical microscope. The results are shown in Figure 10. The obtained particles were not hollow, but had a structure opposite to that of Example 1, with the polymer on the inside and the oil phase on the outside.

[0263] [Comparative Example 11] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2, and were observed under an optical microscope. The results are shown in Figure 11. A porous body was obtained.

[0264] [Comparative Example 12] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the composition was as shown in Table 2, and observed under an optical microscope. The results are shown in Figure 12. The particles obtained were not hollow, but had a structure opposite to that of Example 1, with the polymer on the inside and the oil phase on the outside.

[0265] [Example 7] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that CF2=CF-(CF2)2-O-CF=CF2 was used as the polyfunctional monomer.

[0266] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 13. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 18.7 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0267] [Example 8] The phase-separated microparticles obtained in Example 7 were freeze-dried under the conditions of Example 2, and then observed with an SEM, confirming that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 110°C.

[0268] [Example 9] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer in Example 1 was changed to 70 / 30 (0.21 g / 0.09 g) and the mixing ratio with the non-polymerizable solvent was changed to 60 / 40 (total amount of monomers: 0.3 g / non-polymerizable solvent: 0.2 g).

[0269] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 14. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 21.1 μm. The porosity M of the phase-separated fine particles was 40% by volume.

[0270] [Example 10] The phase-separated microparticles obtained in Example 9 were freeze-dried under the conditions of Example 2, and then observed with an SEM. It was confirmed that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0271] [Example 11] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that CF2=CF-(CF2)2-O-CF=CF2 was used as the polyfunctional monomer and the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer in Example 1 was changed to 30 / 70 (0.075 g / 0.175 g).

[0272] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 15. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 11.4 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0273] [Example 12] The phase-separated microparticles obtained in Example 11 were freeze-dried under the conditions of Example 2, and then observed with an SEM, confirming that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 109°C.

[0274] [Example 13] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that F(CF2)3CH2OH having an SP value of 9.36 was used as the non-polymerizable solvent.

[0275] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 16. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from an optical micrograph was 29.2 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0276] [Example 14] The phase-separated microparticles obtained in Example 13 were freeze-dried under the conditions of Example 2, and then observed with an SEM. It was confirmed that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 109°C.

[0277] [Example 15] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that F(CF2)4CH2OH having an SP value of 9.01 was used as the non-polymerizable solvent.

[0278] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 17. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 24.8 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0279] [Example 16] The phase-separated microparticles obtained in Example 15 were freeze-dried under the conditions of Example 2, and then observed with an SEM, confirming that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0280] [Example 17] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that a homopolymer of CF2=CF-OCF2CF2COOH having Mw=8,000 was used as the fluorine-containing particle dispersion stabilizer of the particle dispersion stabilizer in Example 1.

[0281] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 18. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 12.8 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0282] [Example 18] The phase-separated microparticles obtained in Example 17 were freeze-dried under the conditions of Example 2, and then observed with an SEM. It was confirmed that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0283] [Example 19] Particles dispersed and suspended in water were prepared in the same manner as in Example 1, except that polyvinylpyrrolidone having Mw=40,000 was used as the polymer dispersion stabilizer of the particle dispersion stabilizer in Example 1.

[0284] An optical microscope photograph of the particles dispersed and suspended in water after polymerization is shown in Figure 19. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed and suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from the optical micrograph was 14.4 μm. The porosity M of the phase-separated fine particles was 50% by volume.

[0285] [Example 20] The phase-separated microparticles obtained in Example 19 were freeze-dried under the conditions of Example 2, and then observed with an SEM. It was confirmed that hollow microparticles having a single-pore structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the obtained hollow microparticles was 130°C.

[0286] [Example 21] The emulsion of hollow microparticles obtained in Example 1 was blended with Zeffle SE405 water-based paint manufactured by Daikin Industries, Ltd., to obtain a paint containing 10% by mass of hollow microparticles in terms of mass % solids. The paint was then bar-coated onto a glass slide and dried at 40°C for 2 hours, then at 70°C for 3 hours and at 150°C for 3 hours to obtain a coating film. The resulting coating film had a uniform appearance and a specific gravity of 1.43. The specific gravity was measured at 24°C using a specific gravity measuring device manufactured by Shimadzu Corporation. The specific gravity of a coating film prepared in the same manner using only the water-based paint Zeffle SE405 was 1.50, and the specific gravity of the coating film when it was assumed that the microparticles of Example 1 did not have a hollow structure was 1.54. These specific gravity measurement results confirmed that the hollow structure of the microparticles was maintained in the coating film obtained in Example 21.

[0287] [Table 2]

[0288] PFDVE:CF2=CF-O-(CF2)3-O-CF=CF2 DMF: dimethylformamide HFCP: 1,1,2,2,3,3,4-heptafluorocyclopentane PVA: Polyvinyl alcohol BPO: Benzoyl peroxide AIBN: Azobisisobutyronitrile

Claims

1. Perfluoromonomers and solvents capable of dissolving the perfluoromonomers and having an SP value of 9.00 to 9.80 (cal / cm ３ ) １／２ A step A of dispersing a solution containing the non-polymerizable solvent in water to obtain a dispersion; a step B of polymerizing the perfluoromonomer to obtain phase-separated microparticles having a single-pore structure, the phase-separated microparticles comprising a perfluororesin, a shell with a single-layer structure, and a core portion containing the non-polymerizable solvent; a step C of removing the non-polymerizable solvent from the phase-separated fine particles to obtain hollow fine particles having a single-pore structure; Including, the perfluoromonomer is a perfluoroolefin containing a monofunctional monomer having one polymerizable reactive group and a polyfunctional monomer having two or more polymerizable reactive groups; In the perfluororesin, a mass ratio of polymerized units based on the monofunctional monomer to polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 75 / 25 to 25 / 75; The method for producing hollow microparticles, wherein the non-polymerizable solvent is a fluorine-containing alcohol.

2. 2. The method for producing hollow microparticles according to claim 1, wherein in step A, the dispersion contains an initiator having an ester group at its terminal.

3. 3. The method for producing hollow fine particles according to claim 2, wherein the ester group is a group represented by --COOR (R is an unbranched alkyl group).

4. In the step A, the dispersion contains a particle dispersion stabilizer, 3. The method for producing hollow microparticles according to claim 1, wherein the particle dispersion stabilizer comprises at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1): General formula (α): CX １ X ２ =CX ３ │ (CX ４ X ５ )a-(O)c-Rf-A (In the formula, X １ , X ２ , X ３ , X ４ and X ５ are independently H, F, CH ３ or CF ３ and X １ , X ２ , X ３ , X ４ and X ５ At least one of the groups is F. a and c may be the same or different and are 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group. General formula (1): Rf§(X － ) ｊ (M ＋ ) ｊ (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X － is -COO － , -PO ３ － , or -SO ３ － and M ＋ Is, H ＋ , N.H. ４ ＋ , and alkali metal ions, and j may be 1 or 2).

5. 5. The method for producing hollow microparticles according to claim 4, wherein the particle dispersion stabilizer further comprises at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

6. In the step A, the dispersion contains a particle dispersion stabilizer, The particle dispersion stabilizer is CF ２ =CFCF ２ CF ２ SO ３ Homopolymer of H, CF ２ =CF-OCF ２ CF ２ 3. The method for producing hollow microparticles according to claim 1, wherein the polymer contains at least one selected from the group consisting of a homopolymer of COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

7. the monofunctional monomer is a cyclic perfluoroolefin, 3. The method for producing hollow microparticles according to claim 1, wherein the polyfunctional monomer is a monomer represented by the following formula (b): CF ２ =CF-Q １ -CF=CF ２ (b) [In the formula, Q １ is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.

8. 8. The method for producing hollow microparticles according to claim 7, wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): 【Chemical 1】 [In the formula, R １２ ~R １５ are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group. 【Chemistry 2】 [In the formula, R １６ ~R １９ are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.

9. 9. The method for producing hollow microparticles according to claim 8, wherein the cyclic perfluoroolefin is a monomer represented by formula (c).

10. the monofunctional monomer is perfluoro(2-methylene-4-methyl-1,3-dioxolane); The polyfunctional monomer is CF ２ =CF-O-(CF ２ ) ３ -O-CF=CF ２ and CF ２ =CFCF ２ CF ２ OCF = CF ２ At least one selected from the group consisting of 3. The method for producing hollow microparticles according to claim 1, wherein the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer in the perfluororesin (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 70 / 30 to 30 / 70.

11. 3. The method for producing hollow microparticles according to claim 1, wherein in step B, the perfluororesin has a glass transition temperature of 60° C. or higher.

12. 12. The method for producing hollow microparticles according to claim 11, wherein in step B, the perfluororesin has a glass transition temperature of 120° C. or higher.

13. 3. The method for producing hollow microparticles according to claim 1, wherein the fluorine-containing alcohol has 2 to 7 carbon atoms.

14. 3. The method for producing hollow microparticles according to claim 1, wherein the fluorine-containing alcohol has a hydrogen atom at the ω-position.

15. The non-polymerizable solvent is H(CF ２ ) ６ CH ２ OH, F(CF ２ ) ３ CH ２ OH and F(CF ２ ) ４ CH ２ 3. The method for producing hollow microparticles according to claim 1, wherein the compound is at least one selected from the group consisting of OH.

16. 3. The method for producing hollow microparticles according to claim 1, wherein the hollow microparticles have an average particle size of 1.0 [mu]m or more.

17. 3. The method for producing hollow microparticles according to claim 1, wherein the hollow microparticles have a porosity of 30% by volume or more.

18. 18. The method for producing hollow microparticles according to claim 17, wherein the hollow microparticles have a porosity of 40% by volume or more.

19. The polymerized resin includes a perfluororesin containing polymerized units based on a perfluoromonomer, Substantially free of non-polymerizable solvents; The average particle size is 1.0 μm or more, Hollow microparticles having a single-hole structure, the perfluoromonomer is a perfluoroolefin containing a monofunctional monomer having one polymerizable reactive group and a polyfunctional monomer having two or more polymerizable reactive groups; In the perfluororesin, a mass ratio of polymerized units based on the monofunctional monomer to polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 70 / 30 to 30 / 70; the non-polymerizable solvent is a fluorine-containing alcohol, the monofunctional monomer is perfluoro(2-methylene-4-methyl-1,3-dioxolane); The polyfunctional monomer is at least one selected from the group consisting of CF 2 ═CF—O—(CF 2 ) 3 —O—CF═CF 2 and CF 2 ═CFCF 2 CF 2 OCF═CF 2 .

20. 20. The hollow microparticle according to claim 19, wherein the glass transition temperature of the perfluororesin is 60° C. or higher.

21. 21. The hollow microparticle according to claim 20, wherein the glass transition temperature of the perfluororesin is 120° C. or higher.

22. 21. The hollow microparticles according to claim 19 or 20, wherein the porosity is 30% by volume or more.

23. 23. The hollow microparticles according to claim 22, wherein the porosity is 40% by volume or more.

24. the perfluororesin contains a particle dispersion stabilizer, 21. The hollow microparticle according to claim 19 or 20, wherein the particle dispersion stabilizer comprises at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1): General formula (α): CX １ X ２ =CX ３ │ (CX ４ X ５ )a-(O)c-Rf-A (In the formula, X １ , X ２ , X ３ , X ４ and X ５ are independently H, F, CH ３ or CF ３ and X １ , X ２ , X ３ , X ４ and X ５ At least one of the groups is F. a and c may be the same or different and are 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group. General formula (1): Rf§(X － ) ｊ (M ＋ ) ｊ (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X － is -COO － , -PO ３ － , or -SO ３ － and M ＋ Is, H ＋ , N.H. ４ ＋ , and alkali metal ions, and j may be 1 or 2).

25. The hollow microparticles according to claim 24, wherein the particle dispersion stabilizer further comprises at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

26. the perfluororesin contains a particle dispersion stabilizer, The particle dispersion stabilizer is CF ２ =CFCF ２ CF ２ SO ３ Homopolymer of H, CF ２ =CF-OCF ２ CF ２ 21. The hollow microparticle according to claim 19, comprising at least one selected from the group consisting of a homopolymer of COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

27. The non-polymerizable solvent is H(CF ２ ) ６ CH ２ OH, F(CF ２ ) ３ CH ２ OH and F(CF ２ ) ４ CH ２ 21. The hollow microparticle according to claim 19, which is at least one selected from the group consisting of OH.

28. The hollow fine particles according to claim 19 or 20, which are used as electronic materials.

29. A perfluororesin containing polymerized units based on a perfluoromonomer and a non-polymerizable solvent, The average particle size is 1.0 μm or more, The particles have a single-layer shell and a core containing the non-polymerizable solvent, Phase-separated microparticles having a single-pore structure, the perfluoromonomer is a perfluoroolefin containing a monofunctional monomer having one polymerizable reactive group and a polyfunctional monomer having two or more polymerizable reactive groups; In the perfluororesin, a mass ratio of polymerized units based on the monofunctional monomer to polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 75 / 25 to 25 / 75; The non-polymerizable solvent is a fluorine-containing alcohol.

30. the monofunctional monomer is a cyclic perfluoroolefin, 30. The phase-separated microparticles according to claim 29, wherein the polyfunctional monomer is a monomer represented by the following formula (b): CF ２ =CF-Q １ -CF=CF ２ (b) [In the formula, Q １ is a C1 to C5 perfluoroalkylene group which may have a straight chain or branched chain and which may have an ether bond.

31. The phase-separated microparticles according to claim 30, wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): 【Chemistry 3】 [In the formula, R １２ ~R １５ are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group. 【Chemistry 4】 [In the formula, R １６ ~R １９ are each independently a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.

32. The phase-separated microparticles according to claim 31, wherein the cyclic perfluoroolefin is a monomer represented by formula (c).

33. the monofunctional monomer is perfluoro(2-methylene-4-methyl-1,3-dioxolane); The polyfunctional monomer is CF ２ =CF-O-(CF ２ ) ３ -O-CF=CF ２ and CF ２ =CFCF ２ CF ２ OCF = CF ２ At least one selected from the group consisting of The phase-separated microparticles according to claim 29 or 30, wherein in the perfluororesin, the mass ratio of the polymerized units based on the monofunctional monomer to the polymerized units based on the polyfunctional monomer (polymerized units based on the monofunctional monomer / polymerized units based on the polyfunctional monomer) is 70 / 30 to 30 / 70.

34. 31. The phase-separated microparticles according to claim 29 or 30, wherein the perfluororesin has a glass transition temperature of 60° C. or higher.

35. 35. The phase-separated microparticles according to claim 34, wherein the perfluororesin has a glass transition temperature of 120°C or higher.

36. 31. The phase-separated fine particles according to claim 29 or 30, having a porosity of 30% by volume or more.

37. 37. The phase-separated microparticles according to claim 36, having a porosity of 40% by volume or more.

38. the perfluororesin contains a particle dispersion stabilizer, 31. The phase-separated microparticles according to claim 29 or 30, wherein the particle dispersion stabilizer comprises at least one fluorine-containing particle dispersion stabilizer selected from the group consisting of a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant represented by general formula (1): General formula (α): CX １ X ２ =CX ３ │ (CX ４ X ５ )a-(O)c-Rf-A (In the formula, X １ , X ２ , X ３ , X ４ and X ５ are independently H, F, CH ３ or CF ３ and X １ , X ２ , X ３ , X ４ and X ５ At least one of the groups is F. a and c may be the same or different and are 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having 2 to 100 carbon atoms and an ether bond, or a fluorine-containing alkylene group having 2 to 100 carbon atoms and a keto group. A is -COOM, -SO ３ M, -OSO ３ M or -C(CF ３ ) ２ OM (M is H, metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, and R ７ is H or an organic group. General formula (1): Rf§(X － ) ｊ (M ＋ ) ｊ (wherein Rf§ is a C1 to C30 (per)fluoroalkyl chain or a (per)fluoro(poly)oxyalkylene chain; X － is -COO － , -PO ３ － , or -SO ３ － and M ＋ Is, H ＋ , N.H. ４ ＋ , and alkali metal ions, and j may be 1 or 2).

39. The phase-separated microparticles according to claim 38, wherein the particle dispersion stabilizer further comprises at least one polymer dispersion stabilizer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polymethacrylic acid, polyacrylimide, polyethylene oxide, polyvinylpyrrolidone, and poly(hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer.

40. the perfluororesin contains a particle dispersion stabilizer, The particle dispersion stabilizer is CF ２ =CFCF ２ CF ２ SO ３ Homopolymer of H, CF ２ =CF-OCF ２ CF ２ 31. The phase-separated microparticles according to claim 29 or 30, comprising at least one selected from the group consisting of a homopolymer of COOH, polyvinyl alcohol, and polyvinylpyrrolidone.

41. The non-polymerizable solvent is H(CF ２ ) ６ CH ２ OH, F(CF ２ ) ３ CH ２ OH and F(CF ２ ) ４ CH ２ 31. The phase-separated fine particles according to claim 29 or 30, which are at least one selected from the group consisting of OH.

42. An aqueous dispersion comprising the phase-separated fine particles according to claim 29 or 30.

43. A composition comprising the hollow fine particles according to claim 19 or 20 and an insulating resin.

44. A composition comprising the phase-separated fine particles according to claim 29 or 30 and an insulating resin.

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