Production method of hollow fine particle, hollow fine particle, phase-separated fine particle, aqueous dispersion and composition

Abstract

To provide: a hollow fine particle which contains a perfluoro resin, has a large average particle diameter, and has a single hole structure; and a composition containing the hollow fine particle.SOLUTION: Provided is a hollow fine particle which contains a perfluoro resin containing a polymerization unit based on a perfluoromonomer, substantially contains no non-polymerizable solvent, has an average particle diameter of 1.0 μm or more, and has a single hole structure. The perfluoromonomer is a perfluoroolefin which contains a monofunctional monomer having one polymerizable reactive group and a polyfunctional monomer having two or more polymerizable reactive groups. In the perfluoro resin, a mass ratio of a polymerization unit based on the monofunctional monomer to a polymerization unit based on the polyfunctional monomer ((a polymerization unit based on the monofunctional monomer) / (a polymerization unit based on the polyfunctional monomer)) is 75 / 25-25 / 75, and the non-polymerizable solvent is a fluorine-containing alcohol.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 fine particles having voids inside the particle 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 fine particles, but since inorganic particles are heavy, hollow fine particles made of polymers have been recently studied instead of inorganic particles.

[0003] For example, Patent Document 1 describes hollow resin microparticles containing a resin having fluorine atoms, characterized in that the hollow resin microparticles have 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] JP 2005-213366 A [Patent Document 2] JP 2020-183500 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, since hollow fine particles having a small particle size have a problem in terms of handling, it has been desired to increase the particle size to improve the handling properties. In addition, it has been difficult to produce hollow fine particles containing perfluororesin and having a single-hole structure.

[0007] The present disclosure provides a method for producing hollow microparticles that contain a perfluororesin, have a large average particle size, and have a single-hole 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 a composition that contain the phase-separated microparticles. [Means for solving the problem]

[0008] The present disclosure (1) relates to a perfluoromonomer and a polymerizable solvent 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 present invention relates to a method for producing hollow microparticles comprising 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 above is F. a and c are the same or different and each is 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is 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, The method for producing hollow microparticles according to any one of the present disclosures (1) to (3) is a method for producing hollow microparticles, 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 the 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, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization units based on the polyfunctional monomer) is 75 / 25 to 25 / 75.

[0017] The present disclosure (10) relates to the monofunctional monomer, The method for producing hollow microparticles according to the present disclosure (8) or (9), wherein 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 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0019] The present disclosure (12) relates to 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) relates to a method for producing a polymerizable composition comprising the steps of: The polyfunctional monomer is at least one selected from the group consisting of CF2=CF-O-(CF2)3-O-CF=CF2 and CF2=CFCF2CF2OCF=CF2, The method for producing hollow microparticles according to the present disclosure (9), wherein in the perfluororesin, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization 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 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 volume % or more.

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

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

[0033] The present disclosure (26) relates to the hollow microparticles 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 a method for producing a polymerizable composition comprising the above-mentioned perfluoroolefin, the above-mentioned monofunctional monomer and the above-mentioned polyfunctional monomer, The hollow microparticles according to the present disclosure (26), wherein in the perfluororesin, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization units based on the polyfunctional monomer) is 75 / 25 to 25 / 75.

[0035] The present disclosure (28) relates to a method for producing a polymerizable composition comprising the steps of: The polyfunctional monomer is a monomer represented by the following (b), which is the hollow microparticle according to the present disclosure (26) or (27). 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) relates to the hollow microparticles 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 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0037] The present disclosure (30) relates to the hollow microparticles 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: The polyfunctional monomer is at least one selected from the group consisting of CF2=CF-O-(CF2)3-O-CF=CF2 and CF2=CFCF2CF2OCF=CF2, The hollow microparticles according to the present disclosure (27), wherein in the perfluororesin, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization units based on the polyfunctional monomer) 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 perfluororesin has a glass transition temperature of 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) relates to a method for producing a polymer dispersion dispersion stabilizer comprising the steps of: The hollow microparticles according to any one of the present disclosure (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 above is F. a and c are the same or different and each is 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is 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) relates to a method for producing a polymerizable composition comprising the steps of: The hollow microparticles according to any one of the present disclosures (24) to (35), 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.

[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 directed to hollow fine particles according to any one of the present disclosures (24) to (39) for use as an electronic material.

[0048] The present disclosure (41) relates to a perfluororesin including a polymerized unit based on a perfluoromonomer, and a non-polymerizable solvent, The average particle size is 1.0 μm or more, These are phase-separated particles having a single-pore structure.

[0049] The present disclosure (42) relates to 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 perfluoroolefin comprising the steps of: The phase-separated microparticles according to the present disclosure (43), wherein in the perfluororesin, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization units based on the polyfunctional monomer) is 75 / 25 to 25 / 75.

[0052] The present disclosure (45) relates 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), wherein 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) relates to 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 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0054] The present disclosure (47) relates to 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: The polyfunctional monomer is at least one selected from the group consisting of CF2=CF-O-(CF2)3-O-CF=CF2 and CF2=CFCF2CF2OCF=CF2, The phase-separated microparticles according to the present disclosure (44), wherein in the perfluororesin, a mass ratio of the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization 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 perfluororesin has a glass transition temperature of 120° C. or higher.

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

[0060] The present disclosure (53) relates to a method for producing a polymerizable composition comprising the steps of: 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 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 above is F. a and c are the same or different and each is 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is 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) relates to a method for producing a polymerizable composition comprising the steps of: The phase-separated microparticles according to any one of the present disclosures (41) to (52), 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.

[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. Effect of the Invention

[0067] The production method of the present disclosure can produce hollow microparticles that contain a perfluororesin, have a large average particle size, and have a single-hole structure. The hollow fine particles and the phase-separated fine particles of the present disclosure have a large average particle size, even though they contain a perfluororesin. [Brief description of the drawings]

[0068] [Figure 1] 1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) obtained in Example 1. [Diagram 2] 2 is a SEM photograph of the hollow fine particles (single-porous particles) obtained in Example 2. [Diagram 3] 2 is a 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 water-dispersed suspended particles (monoporous bodies) obtained in Example 3. [Diagram 5] 1 is a SEM photograph of a cross section of a hollow fine particle (single-porous body) obtained in Example 6. [Figure 6] 1 is a SEM photograph of hollow fine particles (porous bodies) obtained in Comparative Example 5. [Figure 7] 1 is a SEM photograph of hollow fine particles (aggregates of fine particles (a type of porous body)) obtained in Comparative Example 7. [Figure 8] 1 is a 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 water-dispersed suspended particles obtained in Comparative Example 10 (the structure is reversed from that of Example 1). [Figure 11] 1 is an optical microscope photograph of the water-dispersed suspended particles (porous body) obtained in Comparative Example 11. [Figure 12] 1 is an optical microscope photograph of the water-dispersed suspended particles obtained in Comparative Example 12 (the structure is reversed from that of Example 1). [Figure 13]1 is an optical microscope photograph of the water-dispersed suspended particles (monoporous bodies) 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 PREFERRED EMBODIMENTS

[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 a hydrogen atom from an organic compound. Examples of the "organic group" are: an alkyl group which may have 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 which may have 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 is independently an alkyl group which may have 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 which may have 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" means 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 sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide 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 carbon atoms, 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 total carbon atoms, 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 carbon atoms, 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 an acylamino group having a total of 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and 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.

[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 carbon atoms, 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 a total of 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 an alkoxy group 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, a methoxyethoxy group, etc.

[0086] The aromatic amino group and the heterocyclic amino group may have an aliphatic group, an aliphatic oxy group, a halogen atom, a carbamoyl group, a heterocyclic group condensed 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 is an alkylthio group 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, or 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 (eg, 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 of manufacturing hollow microparticles) The manufacturing method of the present disclosure is a method for producing a perfluoromonomer and a polymerizable solvent 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 in the phase-separated microparticles to obtain hollow microparticles having a single-pore structure.

[0092] The present inventors have conducted research 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-hole structure by conventional methods. The present inventors have found that hollow microparticles containing perfluororesin, having a large average particle size and a single-hole structure can be obtained by the above-mentioned steps A to C, and have completed the manufacturing method of the present disclosure.

[0093] In step A, perfluoromonomers and a solvent capable of dissolving perfluoromonomers and having an SP value of 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 the droplets, phase-separated fine particles having a large average particle size and a single-hole structure can be obtained. Then, by removing the non-polymerizable solvent in the phase-separated fine particles, hollow fine particles having a large average particle size and a single-hole structure can be obtained. In the production method of the present disclosure, the shell of the hollow fine particles is formed by a perfluororesin. Hereinafter, in this specification, a resin containing a constitutional unit based on a perfluoromonomer is referred to as a perfluororesin.

[0094] The reason why a 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 phase separation from proceeding sufficiently 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 the non-polymerizable solvent, a hydrophilic group is introduced to the terminal of the polymer, and a polymer with a highly hydrophilic terminal is obtained. This promotes the precipitation of the polymer on the surface of the droplets, and the phase separation proceeds sufficiently, resulting in the formation of phase-separated microparticles with a single-pore structure.

[0095] In step A, a dispersion medium other than water may be used together with water. 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 of the dispersion medium other than water include dimethylformamide, dimethylsulfoxide, dimethylacetamide, n-methylpyrrolidone, methanol, ethanol, propanol, and isopropanol.

[0096] Examples of the perfluoromonomer include perfluoroacrylic monomer, perfluorostyrene monomer, and perfluoroolefin, with perfluoroolefin 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 monofunctional monomer and a polyfunctional monomer in combination.

[0098] As the monofunctional monomer, a cyclic perfluoroolefin can be suitably used, and as the polyfunctional monomer, a monomer represented by the following formula (b) (cyclopolymerizable monomer) can be suitably used. By using these monomers, a cyclic structure is introduced into the main chain of the polymer, so that a polymer with a high glass transition temperature can be obtained. 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 an olefin having a cyclic structure and a high fluorine substitution rate. The cyclic perfluoroolefin is not particularly limited, but a monomer represented by the following (a) or (c) can be suitably used. [ka] [In the formula, R 12 ~R 15 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.] [ka] [In the formula, R 16 ~R 19 each independently represents 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 preferable that three of the groups are fluorine atoms and one of the groups is a perfluoromethyl group.

[0102] In formula (b), Q 1 It is preferable that the ether bond is present. 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 the carbon atoms of the group. From the viewpoint of excellent cyclopolymerization, it is preferable that the ether bond is 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. In particular, perfluoro(3-butenyl vinyl ether) is 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 them, 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, with CF2=CF-O-(CF2)3-O-CF=CF2 and CF2=CF-(CF2)2-O-CF=CF2 being even more preferred, and CF2=CF-O-(CF2)3-O-CF=CF2 being particularly preferred.

[0105] In addition, the monomer represented by formula (b) has two polymerizable reactive groups, and therefore can function as a crosslinkable monomer. When functioning as a crosslinkable 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-hole structure as in the present disclosure, it 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, and 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 As shown in formula (II-2) and formula (II-3), three double bonds may be connected to Q to form an aliphatic ring. 1 and may form an aliphatic ring together with Q, or as shown in formula (II-4), 1 Together with Q, they may form an aliphatic ring. 1As the aliphatic ring containing the ring, five-membered and six-membered rings are likely to be produced, and the polymer produced by cyclopolymerization is 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 each independently represents a fluorine atom, a C1 to C5 perfluoroalkyl group, or a C1 to C5 perfluoroalkoxy group.]

[0109] The monomer represented by formula (d) is, for example, 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 Of 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 fluorine-free monomer may be a monofunctional monomer or a polyfunctional monomer.

[0113] Examples of the non-fluorine-containing monomer that corresponds to the polyfunctional monomer 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, and ethylene oxide modified trimethylolpropane tri(meth)acrylate; pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, diaryl compounds or triaryl compounds such as diaryl phthalate, diaryl maleate, diaryl fumarate, diaryl succinate, and triaryl isocyanurate; divinylbenzene, butadiene, 1,6-hexanediol divinyl ether, etc. Examples of the fluoroacrylate include ethylene glycol divinyl ether, 1,4-butanediol divinyl ether, cyclohexane dimethanol divinyl ether, diethylene glycol divinyl ether, and triethylene glycol divinyl ether; di-alpha fluoroacrylates such as ethylene glycol di-alpha fluoroacrylate, diethylene glycol di-alpha fluoroacrylate, triethylene glycol di-alpha fluoroacrylate, 1,6-hexanediol di-alpha fluoroacrylate, and trimethylol propane di-alpha fluoroacrylate; tri-alpha fluoroacrylates such as trimethylol propane tri-alpha fluoroacrylate, ethylene oxide-modified trimethylol propane tri-alpha fluoroacrylate, and pentaerythritol tri-alpha fluoroacrylate; tetra-alpha fluoroacrylates such as pentaerythritol tetra-alpha fluoroacrylate; and hexa-alpha fluoroacrylates such as dipentaerythritol hexa-alpha 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 non-fluorine-containing 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 the polar group-containing (meth)acrylic monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, and p-chlorostyrene; vinyl esters such as vinyl acetate, vinyl benzoate, vinyl neononanoate (Veova 9), vinyl neodecanoate (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 (product name: Veova 9), vinyl neodecanoate (product name: Veova 10), and vinyl propionate are preferred because they have improved compatibility with perfluoromonomers.

[0115] In step A, the solution containing a perfluoromonomer and a 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 the perfluoromonomer used when only the perfluoromonomer is polymerized, and refers to the total amount of the perfluoromonomer and the monomer copolymerizable with the perfluoromonomer when the perfluoromonomer and the monomer copolymerizable with the perfluoromonomer are polymerized. The ratio of each monomer may be appropriately set according to the desired perfluororesin.

[0116] The non-polymerizable solvent can be a solvent capable of dissolving the perfluoromonomer but having 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 perfluororesin, the non-polymerizable solvent functions as a chain transfer agent, and when the SP value is within this range, it is considered that a hydrophilic group is introduced to the end 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 calculated 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 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 compound represented by the formula (I) and having an SP value in the above range is preferable. Specific examples include those in the table below. The compound represented by this formula is F(CF2) n (CH2) m OH(n=2-4, 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] In addition, the fluorine-containing alcohol preferably has a hydrogen atom at the ω position, since a hydrophilic group is introduced at the end of the polymer (perfluororesin) to further improve the hydrophilicity of the polymer. That is, a compound in which X=H in the above formula is preferred. Specific examples of fluorine-containing alcohols having a hydrogen atom at the ω position include H(CF2)nCH2OH (n=5-7), 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 ratio of the non-polymerizable solvent to the total amount of the solvent 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, and preferably 0.5 to 5 parts by mass, per part by mass of the monomer.

[0124] In step A, the dispersion liquid preferably contains a particle dispersion stabilizer. By containing a particle dispersion stabilizer, phase separation can be further promoted, and hollow fine particles having a large particle size can be obtained. The particle dispersion stabilizer may be mixed in advance with water before step A, or may be mixed in advance with a solution containing a perfluoromonomer and a non-polymerizable solvent, 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 the 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 of such substances include polymer dispersion stabilizers and fluorine-containing particle dispersion stabilizers.

[0126] Examples of the polymer dispersion stabilizer 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] An example of the fluorine-containing particle dispersion stabilizer is 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 above is F. a and c are the same or different and each is 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group having 2 to 100 carbon atoms. A is -COOM, -SO3M, -OSO3M, or -C(CF3)2OM (M is 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 of the fluorine-containing alkylene group is preferably 2 or more. The number of carbon atoms of 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, further preferably 12 or less, particularly preferably 9 or less, and most preferably 6 or less. The fluorine-containing alkylene group having an ether bond can be, 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 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-CF2CF2CF2-, -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, further preferably 12 or less, and particularly preferably 5 or less.

[0132] Specific examples of fluorine-containing alkylene groups having a keto group include -CF2CF(CF3)CO-CF2-, -CF2CF(CF3)CO-CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2-, -CF2CF(CF3)CO-CF2CF2CF2-, 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 having water added to the keto group include -CF2CF(CF3)C(OH)2-CF2-, -CF2CF(CF3)C(OH)2-CF2CF2-, -CF2CF(CF3)C(OH)2-CF2CF2CF2-, -CF2CF(CF3)C(OH)2-CF2CF2CF2CF2-, and the like.

[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, a metal atom, or 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] The metal atom includes alkali metals (Group 1), alkaline earth metals (Group 2), etc., and is preferably Na, K or Li.

[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 CF2=CF-O-Rf-A (formula 1a), Examples include 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 (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 (Formula 2a) As for the following:

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

[0141] Among others

[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 preferable, and CH2=CFCF2OCF(CF3)COOM is more preferable.

[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 contain polymerization units (α) based on two or more different monomers represented by the general formula (α).

[0146] As the other monomer, a monomer represented by the general formula CFR=CR2 (wherein R is independently H, F or a perfluoroalkyl group having 1 to 4 carbon atoms) is preferred. In addition, as the other monomer, a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms is preferred. Examples of the other monomer include CF2=CF2, CF2=CFCl, CH2=CF2, CFH=CH2, CFH=CF2, CF2=CFCF3, CH2=CFCF3, CH2=CHCF3, CHF=CHCF3 (E form), CHF=CHCF3 (Z form), etc.

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

[0148] As the other monomer, there is also a monomer 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 ether bonds having 2 to 100 carbon atoms).

[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 the formula (n1-2)).

[0152] The content of the polymerization unit (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, based on the total polymerization units constituting the fluoropolymer (β). The content of the polymerization unit (β) is particularly preferably substantially 100 mol%, and the fluoropolymer (β) is most preferably composed only of the polymerization unit (β). The higher the content of the polymerization unit (β) in the fluoropolymer (β), the greater the advantage of the water solubility of the fluoropolymer (β).

[0153] In the fluoropolymer (β), the content of polymerization 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 the total polymerization units constituting the fluoropolymer (β). It is particularly preferable that the content of polymerization units based on other monomers copolymerizable with the monomer (β) is substantially 0 mol%, and it is most preferable that the fluoropolymer (β) does not contain polymerization 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 it, 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 Above, 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 groups preferably have 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 an anionic fluorine-containing surfactant. An example of the anionic fluorine-containing surfactant is represented by the 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, 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 having an anionic moiety with a molecular weight of 800 or less. The "anionic portion" refers to 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, including fluoropolymers of monomers represented by the following formula: In the 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 a fluoropolymer (α) of a monomer (α) represented by general formula (α) and an anionic fluorine-containing surfactant 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 monomeric fluoropolymer (α) 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 phase separation promoter. This leads to better 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 1 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 necessary, in water to obtain a dispersion. As a dispersion method, various known methods such as a dispersion method using a mechanical shear force, such as a homogenizer or a membrane emulsification method, can be adopted. The temperature condition during dispersion may be 0°C or higher and lower than 100°C, and preferably 0 to 90°C. When the solution in the dispersion step contains an initiator, the temperature must be lower than a temperature that affects the decomposition of the initiator used, and is usually around room temperature or lower, and particularly preferably about 0 to 30°C.

[0168] In step A, the size of droplets formed by dispersing the solution is usually not monodisperse, but generally a mixture of droplets with various different particle sizes. Therefore, the hollow fine particles finally obtained also have different particle sizes. By selecting a dispersion method, the droplet size can be made uniform to obtain monodispersed droplets. For example, a method for obtaining such monodispersed droplets can be used to prepare monodispersed droplets by a membrane emulsification method using porous glass (SPG). When such monodispersed droplets with a uniform particle size are prepared, the hollow microparticles finally obtained are also monodispersed with a 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 the polymerization initiator is added to the solution before step A, polymerization may start in 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 is one that initiates polymerization of monomers in droplets formed by dispersing a solution in water, and can be any of those that have been used conventionally, such as oil-soluble initiators. For example, radical polymerization initiators include 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); peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, and lauroyl peroxide; and the like. In addition, 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] The polymerization initiator may be a compound represented by the following formulae (C1), (C2) or (C3) (hereinafter, these may be referred to as "compound (C1)", "compound (C2)" or "compound (C3)", respectively), or an inorganic peroxide. 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, perfluoro 2-phenyl-2-propyl, perfluorobutyl, perfluoro sec-butyl, perfluoro tert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro 2-methyl-2-pentyl, perfluoro 2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro 2-methylhexyl, perfluoro 2-ethylhexyl, perfluorocyclohexyl, perfluoro 4-methylcyclohexyl, perfluoro 4-ethylcyclohexyl, perfluoro 4-tertbutylcyclohexyl, perfluoroheptyl, perfluoro 2-heptyl, perfluoro 3-heptyl, perfluorooctyl, perfluoro 2-methyl-2-octyl, perfluorononyl, perfluorodecyl, perfluorophenyl, perfluoro 2-methylphenyl, perfluoro 3-methylphenyl, or perfluoro 4-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 is more preferably the same or different and is 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, perfluoro 2-phenyl-2-propyl, perfluorobutyl, perfluoro sec-butyl, perfluoro tert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro 2-methyl-2-pentyl, perfluoro 2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro 2-methylhexyl, perfluoro 2-ethylhexyl, perfluorocyclohexyl, perfluoro 4-methylcyclohexyl, perfluoro 4-ethylcyclohexyl, perfluoro 4-tertbutylcyclohexyl, perfluoroheptyl, perfluoro 2-heptyl, perfluoro 3-heptyl, perfluorooctyl, perfluoro 2-methyl-2-octyl, perfluorononyl, perfluorodecyl, perfluorophenyl, perfluoro 2-methylphenyl, perfluoro 3-methylphenyl, or perfluoro 4-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, 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 each of which has at least one fluorine atom substituted with a hydrogen atom, such as perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluoro 2-phenyl-2-propyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluoroisopentyl, perfluoroneopentyl, perfluoro 2-methyl-2-pentyl, perfluoro 2,4,4-trimethyl-2-pentyl, perfluorohexyl, perfluoro 2- perfluorooctyl, perfluoro-2-methyl-2-octyl, perfluorononyl, perfluorodecyl, perfluorophenyl, perfluoro-2-methylphenyl, perfluoro-3-methylphenyl, and perfluoro-4-methylphenyl.

[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, percarbonic acid and permanganic acid. 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 above initiator, the ester group may be present at one end, but is preferably present at both ends. The ester group is preferably a group represented by -COOR (R is an unbranched alkyl group). The alkyl group of R is preferably a C1 to C5 alkyl group, more preferably a C1 to C3 alkyl group, and further 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 have a fluorine atom or an aromatic ring.

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

[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 monomer copolymerizable with the perfluoromonomer.

[0190] The polymerization in step B can be carried out using 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 for initiating polymerization of the perfluoromonomer (and a monomer copolymerizable with the perfluoromonomer, which is used as necessary) by 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 carried out until the desired hollow fine particles are obtained. The time required for the polymerization varies depending on the types of the fluorine-containing monomer (and the monomer copolymerizable with the fluorine-containing monomer, which is used as necessary), the polymerization initiator, and the 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 polymer has a single-layer shell and a core portion in which the non-polymerizable solvent is encapsulated. The shell portion of the phase-separated microparticles is composed of a perfluororesin containing a polymerization unit based on a perfluoromonomer (or a polymerization unit 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 using a DSC (differential scanning calorimeter: DSC7000 manufactured by Hitachi High-Tech Science Corporation) by heating (first run)-cooling-heating (second run) in the temperature range from 30° C. to 200° C. at a rate of 10° C. / min, and is determined as the midpoint of the endothermic curve in the second run.

[0196] The perfluororesin may consist only 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 the perfluoromonomer are preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total polymerized units. The upper limit is not particularly limited, and may be 100% by mass. When the polymerized units based on the perfluoromonomer are in the above range, the electrical properties of the obtained hollow microparticles are good.

[0198] The perfluororesin preferably contains a polymerization unit based on a perfluoromonomer corresponding to a monofunctional monomer and a polymerization unit based on a polyfunctional monomer (crosslinkable monomer), which strengthens the shell of the hollow microparticles, thereby making it possible to reduce the shell thickness and increase the porosity. The polyfunctional monomer may be any of perfluoromonomer, fluorine-containing monomer other than perfluoromonomer, and non-fluorine-containing monomer, but perfluoromonomer is preferable. That is, the perfluororesin preferably contains a polymerization unit based on a perfluoromonomer corresponding to a monofunctional monomer and a polymerization unit 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 realizes high electrical properties.

[0199] In the perfluororesin, the polymerized units based on the polyfunctional monomer (crosslinkable monomer) are preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more, based on the total polymerized units. Also, the polymerized units based on the crosslinkable monomer are preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 55% by mass or less. By having the polymerized units based on the crosslinkable monomer in the above range, the obtained hollow microparticles can be excellent in strength and electrical properties.

[0200] In the perfluororesin, the polymerized units based on the non-fluorinated monomer preferably account for 0 to 70 mass %, more preferably 0 to 50 mass %, of the total polymerized units.

[0201] In the perfluororesin, the polymerized units based on a fluorine-containing monomer other than a perfluoromonomer 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, based on 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 it is in the above range, the dispersion stability in water is increased, and the storage stability is excellent. 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. When the fluorine content is 10% by mass or more, the electrical properties and water resistance become better. The fluorine content is more preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more. The hollow microparticles containing such a perfluororesin can be obtained by the above-mentioned production method of the present disclosure, particularly the 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 polymerization units (C) based on a monofunctional perfluoromonomer (perfluoroolefin) to the polymerization 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, further 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. The refractive index is 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 in the phase-separated fine particles to obtain hollow fine particles. By step C, hollow fine particles substantially free of the non-polymerizable solvent can be 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 viewpoint of simplicity and economy. Freeze-drying is also preferred because it is easy 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 it is preferable to heat the material 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 manufacture hollow microparticles having a large particle size by steps A to C. The average particle size 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 size 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) method. It can also be 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" does not include a structure having multiple voids such as a porous structure, but refers to a structure having only one closed void. In the following description, the part of the hollow microparticle other than the voids is referred to as the "shell."

[0210] In the hollow fine particles, the pore size of the hollow part is preferably 66% or more, more preferably 74% or more, and even more preferably 79% or more, and is preferably 95% or less, more preferably 93% or less, even more preferably 90% or less, and particularly preferably 88% or less, of the diameter of the hollow fine particles. In the present disclosure, the pore size of the hollow part can be calculated by image analysis of a TEM photograph of the hollow particulate using particle size analysis software LUZEX AP. Specifically, about 200 hollow particulates are randomly selected from the TEM photograph, and the inner radius (R1) is measured, and the pore size of the hollow part can be calculated by 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, further preferably 10% or less, and particularly preferably 9% or less. A thinner shell results in a higher porosity, and therefore the hollow particles can 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, about 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, whereby the shell thickness can be calculated according to 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. If the porosity is high, the relative dielectric constant of the hollow fine particles can be reduced, making them suitable for use as electrical materials. The upper limit of the porosity is not particularly limited, 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, further 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 this 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 have a small content of the phase separation promoter. Therefore, in the production method of the present disclosure, it is preferable to use as little of the phase separation promoter as possible. In the hollow fine particles, the content of the phase separation promoter is, for example, preferably 5% by mass or less, more preferably 1% by mass or less, and more 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 spaces of the hollow particles are preferably filled with a gas, and more preferably with 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 are also applicable to the hollow microparticles of the present disclosure. Furthermore, the production method of the present disclosure makes it possible to obtain hollow fine particles that maintain their particle shape even in an isolated state.

[0217] The hollow microparticles of the present disclosure contain a perfluoro resin 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 size of the droplets in the manufacturing method of the present disclosure described above. However, with conventional methods, it has been difficult to increase the average particle size of hollow microparticles containing perfluororesin. By using the above-described production method of the present disclosure, it is possible to increase the average particle size even of hollow microparticles containing a perfluororesin, and it is possible to produce 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, the term "substantially free of non-polymerizable solvents" means that the non-polymerizable solvent 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 fine particles of the present disclosure have an average particle size of 1.0 μm or more. The average particle size is preferably 2.0 μm or more, and more preferably 5.0 μm or more. The average particle size is 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-hole structure, and therefore have excellent low dielectric properties and high frequency characteristics, and are therefore suitable for use as electronic materials. That is, the hollow fine particles of the present disclosure are preferably used as electronic materials. In addition, when a hollow microparticle has a porous structure, when it is used as an additive, the degree of voids is significantly reduced by the infiltration of the matrix resin into the pores, and the desired electrical properties may not be obtained. In contrast, the hollow microparticles of the present disclosure have a single-pore structure, and therefore have the advantage that such problems are unlikely to occur and the electrical properties can be easily adjusted to the desired values.

[0222] In addition, the hollow microparticles of the present disclosure contain perfluororesin and have an average particle size of 1.0 μm or more, and therefore have excellent low dielectric properties and can reduce the surface area when used in the same volume. From this point of view, they are suitable for use as electronic materials. If the average particle size is small, the specific surface area increases, and the electrical properties may be significantly reduced due to the influence of moisture adhering to the interface.

[0223] (phase separated fine particles) By carrying out steps A to 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, 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 are also applicable 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 are different from the hollow microparticles of the present disclosure in that the hollow portion contains a non-polymerizable solvent. The content of the non-polymerizable solvent is preferably 10% by mass or more, more preferably 30% by mass or more, based on 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 phase-separated microparticles.

[0226] The phase-separated fine particles of the present disclosure have an average particle size of 1.0 μm or more. The average particle size is preferably 2.0 μm or more, and more preferably 5.0 μm or more. The average particle size is 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) A first composition of the present disclosure comprises the hollow fine particles of the present disclosure and a perfluoro resin 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, silicon resins, benzoxazine resins, melamine resins, urea resins, allyl resins, phenolic resins, unsaturated polyester resins, polyurethane resins, and aniline resins. Among them, fluorine-containing resins, epoxy resins, thermosetting polyimide resins, modified polyphenylene ether resins, thermosetting polyimide resins, silicon resins, benzoxazine resins, and melamine resins are preferred. These insulating resins may be used alone or in combination of two or more. 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 between the insulating resin and 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 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.

[0232] The first composition of the present disclosure is preferable in that the electrical properties are controllable.

[0233] A 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 fine particles and an insulating resin, or may be a composition produced during the process of producing phase-separated fine particles. In the second composition of the present disclosure, phase-separated fine particles are preferably 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. As the insulating resin, the one described in the first composition of the present disclosure can be used.

[0236] In the second composition of the present disclosure, the composition ratio of the insulating resin and the phase-separating fine particles is not limited, but may be, for example, any composition in which the mass ratio (insulating resin / phase-separating 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 are controllable, 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 of high-frequency connectors, etc. They are particularly useful in high-frequency compatible substrates used in 5G and 6G. EXAMPLES

[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 was the same for phase-separated microparticles and hollow microparticles.

[0242] [Porosity] The porosity was calculated by the following formula. Porosity M (volume%) = amount of non-polymerizable solvent (g) / (total amount of monomer (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 temperature was increased (first run) - decreased - increased (second run) in the temperature range from 30°C to 200°C at 10°C / min, 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 from the charged monomer ratio (total ratio Q of the monomer amount to the total weight) using the following formula. Polymerization rate C(%) = Z / Q×100(%)

[0245] [Example 1] As a perfluoromonomer corresponding to a monofunctional monomer, perfluoro(2-methylene-4-methyl-1,3-dioxolane) (monomer a7 (monomer represented by formula (a-7))) was used. As a perfluoromonomer corresponding to a polyfunctional monomer, 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) was used. As a non-polymerizable solvent, 2,2- 3,3-4,4-5,5-6,6-7,7-dodecafluoro-1-heptanol (H(CF2)6CH2OH) was used; as a 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 a polymerization initiator, 2,2'-azobis(methyl isobutyrate) (compound below) (initiator (1)), which is an azo compound having an ester group at the end, were used. [ka]

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

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

[0248] [Example 2] The phase-separated microparticles obtained in Example 1 were frozen at -50°C, and then freeze-dried at room temperature at 18 Pa for 24 hours, and then observed by SEM. The results are shown in Figures 2 and 3. It was confirmed that hollow microparticles having a single-hole structure were obtained. The glass transition temperature of the perfluororesin constituting the resulting 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 the 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. In the optical microscope photograph after polymerization, it was confirmed that particles with a hollow structure (single hole) were obtained. The resulting water-dispersed suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 2.85 μm. The porosity M of the phase-separated fine particles was 50 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, confirming that hollow microparticles having a single-hole structure had been obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 the 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 1.60 μm. The porosity M of the phase-separated fine particles was 50 volume %.

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

[0255] [Comparative Examples 1 to 3] Although the perfluoromonomer and the non-polymerizable solvent were mixed in the composition shown 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 in Table 2 was used, 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, and after freeze-drying under the conditions of Example 2, they were observed by SEM. The results are shown in Figure 7. What was obtained was an aggregate of many 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. The particles were freeze-dried under the conditions of Example 2, and then 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 observed under an optical microscope. The results are shown in Figure 9. What was obtained was an aggregate of many 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 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 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.

[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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 18.7 μm. The porosity M of the phase-separated fine particles was 50 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. It was confirmed that hollow microparticles having a single-hole structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 polymerization units based on the monofunctional monomer and the polymerization 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 monomer: 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 21.1 μm. The porosity M of the phase-separated fine particles was 40 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-hole structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 polymerization units based on the monofunctional monomer to the polymerization 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 11.4 μm. The porosity M of the phase-separated fine particles was 50 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. It was confirmed that hollow microparticles having a single-hole structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 29.2 μm. The porosity M of the phase-separated fine particles was 50 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, confirming that hollow microparticles having a single-hole structure had been obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 24.8 μm. The porosity M of the phase-separated fine particles was 50 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 resulting 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 12.8 μm. The porosity M of the phase-separated fine particles was 50 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, confirming that hollow microparticles having a single-hole structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting 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 polymeric 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 suspended particles were phase-separated fine particles containing the non-polymerizable solvent inside. The average particle size calculated from optical micrographs was 14.4 μm. The porosity M of the phase-separated fine particles was 50 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-hole structure were obtained (not shown). The glass transition temperature of the perfluororesin constituting the resulting hollow microparticles was 130°C.

[0286] [Example 21] The emulsion of hollow particles obtained in Example 1 was blended with a water-based paint Zeffle SE405 manufactured by Daikin Industries, Ltd. in a water-based system to obtain a paint in which hollow particles were mixed at 10% by mass based on the mass % of solid content. The paint was then bar-coated on a slide glass, dried at 40°C for 2 hours, then dried at 70°C for 3 hours and at 150°C for 3 hours to obtain a coating film. The appearance of the obtained coating film was uniform, and the specific gravity was 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 fine particles in Example 1 did not have a hollow structure was 1.54. From these specific gravity measurement results, it was confirmed that the hollow structure of the fine particles 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. The present invention includes a perfluororesin including a polymerized unit based on a perfluoromonomer, Substantially free of non-polymerizable solvents; The average particle size is 1.0 μm or more, A hollow microparticle 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 the polymerization units based on the monofunctional monomer to the polymerization units based on the polyfunctional monomer (polymerization units based on the monofunctional monomer / polymerization units based on the polyfunctional monomer) is 75 / 25 to 25 / 75; The non-polymerizable solvent is a fluorine-containing alcohol.

2. the monofunctional monomer is a cyclic perfluoroolefin, 2. The hollow microparticle 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.

3. 3. The hollow microparticle according to claim 2, wherein the cyclic perfluoroolefin is a monomer represented by the following (a) or (c): [Chemical formula 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. [Chemical 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.

4. 4. The hollow microparticle according to claim 3, wherein the cyclic perfluoroolefin is a monomer represented by the formula (c).

5. 3. The hollow microparticles according to claim 1, wherein the perfluororesin has a glass transition temperature of 60° C. or higher.

6. 6. The hollow microparticle according to claim 5, wherein the perfluororesin has a glass transition temperature of 120° C. or higher.

7. 3. The hollow microparticle according to claim 1, wherein the porosity is 30% by volume or more.

8. 8. The hollow microparticle according to claim 7, having a porosity of 40% by volume or more.

9. The perfluororesin contains a particle dispersion stabilizer, 3. The hollow microparticle according to claim 1 or 2, 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 are the same or different and each is 0 or 1. Rf is a fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having an ether bond and having 2 to 100 carbon atoms, or a fluorine-containing alkylene group having a keto group and having 2 to 100 carbon atoms. 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; 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 ＋ H ＋ , N.H. ４ ＋ , an alkali metal ion, and j may be 1 or 2).

10. The hollow microparticle according to claim 9, 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.

11. 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 3. The hollow microparticle according to claim 1, which comprises at least one member selected from the group consisting of a homopolymer of COOH, polyvinyl alcohol and polyvinylpyrrolidone.

12. 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 hollow fine particles according to claim 1, which are at least one type selected from the group consisting of OH.

13. 3. The hollow fine particles according to claim 1 or 2, which are used as electronic materials.

14. A composition comprising the hollow fine particles according to claim 1 or 2 and an insulating resin.

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