Manufacturing method of hollow microparticles and hollow microparticles

Abstract

This invention provides a method for manufacturing hollow microparticles containing fluorinated resin and having a large average particle size. The method comprises: a dispersion step in which a solution containing a fluorinated monomer, a phase separation promoter, and a non-polymerizable solvent is dispersed in water to obtain a dispersion; and a polymerization step in which the fluorinated monomer is polymerized to obtain hollow microparticles containing fluorinated resin.

Description

Technical Field

[0001] This invention relates to a method for manufacturing hollow microparticles and hollow microparticles. Prior Technology

[0002] Hollow microparticles with internal pores are highly regarded for their advantages in lightweighting, low refractive index, and low dielectric properties, and have been the subject of various studies. In the past, inorganic particles were used as such hollow microparticles; however, due to their relatively heavy weight, recent research has focused on obtaining hollow microparticles from polymers to replace inorganic particles.

[0003] For example, Patent Document 1 describes a hollow resin microparticle, which is a hollow resin microparticle containing resin with fluorine atoms, and is characterized by: an average particle size of 10~200 nm, a porosity of more than 10%, and a refractive index of less than 1.30.

[0004] Patent document 2 describes a method for manufacturing microparticles containing a target component, which involves dispersing a mixture containing the target component, a specific monomer component, a specific auxiliary polymer and an initiator in an aqueous solution of a dispersion stabilizer and then performing suspension polymerization. [Previous Technical Documents] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2005-213366 [Patent Document 2] Japanese Patent Application Publication No. 2003-96108 Summary of the Invention

[0006] [The problem that the invention aims to solve]

[0007] This invention provides a method for manufacturing hollow microparticles containing fluorinated resin and having a large average particle size. Furthermore, this invention provides hollow microparticles containing fluorinated resin and having a large average particle size. [Technical means to solve the problem]

[0008] This invention relates to a method for manufacturing hollow microparticles, comprising: a dispersion step in which a solution containing a fluorinated monomer, a phase separation promoter and a non-polymerizable solvent is dispersed in water to obtain a dispersion; and a polymerization step in which the fluorinated monomer is polymerized to obtain hollow microparticles containing a fluorinated resin.

[0009] The fluorinated monomers mentioned above are preferably monomers represented by the following general formula (B1): CX 1X 2=CY 1Z (B 1) (In the formula, X1, X2, and Y1 are independently H, CH3, F, or Cl; Z is F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms)) and the following formula: (where X6~X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1~8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein any one of X1, X2, Y1 and Z contains more than one F). Furthermore, the aforementioned fluorinated monomer is preferably a fluorinated acrylic acid monomer represented by the following general formula (C1): CH 2=CX 3-COORf 2(C 1) (In the formula, X3 is H, CH3, F, Cl or CF3, and Rf2 is a fluorinated alkyl group with 1 to 20 carbon atoms that can contain ether bonds between carbon atoms).

[0010] The aforementioned phase separation promoter is preferably soluble in the aforementioned non-polymerizable solvent at room temperature. When the Sp value of the aforementioned phase separation promoter is set to SA (J / cm³)¹ / ², and the Sp value of the aforementioned non-polymerizable solvent is set to SB (J / cm³)¹ / ², the following relationship is satisfied: |SA-SB|<3(J / cm 3) 1 / 2. Furthermore, the aforementioned phase separation promoter is preferably a polymer comprising polymerization units based on monomers represented by the following general formula: CH 2=CX 4Y 2 (where X4 is H, CH3, F, Cl, or CF3, and Y2 is Cl, C6H4R1, C6H3R2R3, COOR4, or OCOR5 (here, R1, R2, R3, R4 and R5 are independently H, OH, or alkyl groups with 1 to 40 carbon atoms that can be substituted by halogen atoms)), preferably at least one of the following groups: aromatic vinyl polymers and poly(meth)acrylate alkyl esters.

[0011] The preferred fluorine content of the aforementioned fluorine-containing monomers is 30% by mass or higher.

[0012] The solution described above preferably contains a cross-linking monomer.

[0013] The aforementioned non-polymerizable solvents are preferably aromatic hydrocarbons, esters, or saturated hydrocarbons with 8 to 18 carbon atoms, or halogenated derivatives thereof.

[0014] The above dispersion step is preferably a step of dispersing the above solution in water at a temperature of 50°C or higher to obtain a dispersion, or... The steps include dispersing the above solution in water at a temperature below 50°C to obtain a dispersion, and heating the obtained dispersion to a temperature above 50°C. Furthermore, the manufacturing method of the present invention is preferably further comprising, after the dispersion step and before the polymerization step, adding an oil-soluble initiator to the dispersion.

[0015] Preferably, the process includes a removal step that removes the non-polymerizable solvent from the hollow microparticles obtained from the polymerization step described above.

[0016] The average particle size of the aforementioned hollow microparticles is preferably above 1.0 μm.

[0017] Furthermore, the present invention also relates to a hollow microparticle containing a fluorinated resin D comprising a polymer unit based on a fluorinated monomer, and having an average particle size of 1.0 μm or more.

[0018] The fluorinated monomer mentioned above is preferably the monomer (B2) represented by the following general formula (B2): CX 1X 2=CY 1Z (B 2) (In the formula, X1, X2, and Y1 are independently the same or different, and are H, CH3, F, or Cl; Z is F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms)) and the group represented by the following formula: (where X6~X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1~8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein any one of X1, X2, Y1 and Z contains more than one F). Furthermore, the aforementioned fluorinated monomer is preferably a fluorinated acrylic acid monomer represented by the following general formula (C2): CH₂=CX₃-COORf₂(C₂) (In the formula, X3 is H, CH3, F, Cl or CF3, and Rf2 is a fluorinated alkyl group with 1 to 20 carbon atoms that can contain ether bonds between carbon atoms).

[0019] The aforementioned hollow microparticles are preferably those containing a phase separation promoter. The aforementioned phase separation promoter is preferably a polymer comprising polymerization units based on monomers represented by the following general formula: CH 2=CX 4Y 2 (where X4 is H, CH3, F, Cl, or CF3, and Y2 is Cl, C6H4R1, C6H3R2R3, COOR4, or OCOR5 (here, R1, R2, R3, R4 and R5 are independently H, OH, or alkyl groups with 1 to 40 carbon atoms that can be substituted by halogen atoms)), preferably at least one of the following groups: aromatic vinyl polymers and poly(meth)acrylate alkyl esters.

[0020] The aforementioned fluorinated resin D is preferably a polymeric unit comprising a crosslinking monomer. Furthermore, the fluorine content of the aforementioned fluorinated resin D is preferably 15% by mass or more.

[0021] The hollow microparticles of the present invention are preferably composed of a shell containing the above-mentioned fluorinated resin D and a hollow portion, and have a single-pore structure.

[0022] Furthermore, the present invention also relates to a hardening composition comprising the aforementioned hollow microparticles.

[0023] Furthermore, the present invention also relates to a coating composition comprising the aforementioned hollow microparticles.

[0024] The hollow microparticles of this invention are preferably used in electronic materials. [Effects of the Invention]

[0025] The method for manufacturing hollow microparticles of the present invention can produce hollow microparticles containing fluorinated resin and having a large average particle size. Furthermore, the hollow microparticles of the present invention, regardless of whether they contain fluorinated resin, have a large average particle size. Simple Explanation of the Diagram

[0026] [Figure 1] Figure 1(a) is an optical microscope photograph of the suspended droplets before polymerization in Example 1, and Figure 1(b) is an optical microscope photograph of the hollow microparticles after polymerization. [Figure 2] Figure 2 is a SEM image of the polymerized hollow microparticles in Example 1. [Figure 3] Figure 3(a) is an optical microscope photograph of the suspended droplets before polymerization in Example 2, and Figure 3(b) is an optical microscope photograph of the microparticles after polymerization. [Figure 4] Figure 4(a) is an optical microscope photograph of the suspended droplets before polymerization in Comparative Example 2, and Figure 4(b) is an optical microscope photograph of the microparticles after polymerization. [Figure 5] Figure 5(a) is an optical microscope photograph of the suspended droplets before polymerization in Example 4, and Figure 5(b) is an optical microscope photograph of the microparticles after polymerization. [Figure 6] Figure 6(a) is a SEM image of the particles obtained in Example 4, Figure 6(b) is an EDX mapping image of the shell wall, and Figure 6(c) is a SEM image of the particles after they are broken. [Figure 7] Figure 7(a) is an optical microscope photograph of the suspended droplet before polymerization in Example 5. [Figure 8] Figure 8(a) is an optical microscope photograph of the polymerized hollow microparticles in Example 5, and Figure 8(b) is a SEM photograph of the polymerized hollow microparticles. [Figure 9] is an example of a cross-sectional SEM image of membrane 2 produced by membrane fabrication 1. [Figure 10] is an example of a cross-sectional SEM image of membrane 2 produced by membrane fabrication 1. [Figure 11] is a graph showing the amount of microparticles added as the horizontal axis and the dielectric loss tangent as the vertical axis for the membrane produced in the embodiment. Implementation

[0027] This invention relates to a method for manufacturing hollow microparticles, comprising: a dispersion step in which a solution containing a fluorinated monomer, a phase separation promoter and a non-polymerizable solvent is dispersed in water to obtain a dispersion; and a polymerization step in which the fluorinated monomer is polymerized to obtain hollow microparticles containing a fluorinated resin. The inventors, through their research, discovered that in the case of polymerizing fluorinated monomers to obtain hollow microparticles containing fluorinated resin, conventional methods often fail to yield hollow microparticles with a large average particle size. The inventors found that by dispersing a solution containing fluorinated monomers, a phase separation promoter, and a non-polymerizing solvent in water before polymerization, even hollow microparticles containing fluorinated resin can have a larger average particle size, thus completing the method for manufacturing hollow microparticles according to the present invention.

[0028] The above dispersion step involves dispersing a solution containing a fluorinated monomer, a phase separation promoter, and a non-polymerizable solvent in water to obtain a dispersion. By dispersing the above solution to form droplets, the fluorinated monomer can be polymerized within these droplets. At this time, phase separation is promoted by the phase separation promoter, and even in the case of fluorinated resins, hollow microparticles with a large average particle size can be obtained.

[0029] Examples of fluorinated monomers include fluorinated acrylic acid monomers, fluorinated styrene monomers, and fluorinated olefins, without particular limitation. A preferred example is the monomer represented by the following general formula (B1): CX 1X 2=CY 1Z (B 1) (In the formula, X1, X2, and Y1 are independently H, CH3, F, or Cl; Z is F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms)) and the following formula: (where X6~X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1~8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein any one of X1, X2, Y1 and Z contains more than one F).

[0030] From the perspective of self-aggregation, X1 and X2 are preferably independently H, CH3 or F, X1 and X2 are more preferably the same and are F or H, and even more preferably the same and are H.

[0031] From the viewpoint of self-polymerization and the heat resistance of polymers, the above-mentioned Y1 is preferably H, CH3 or F, more preferably CH3 or F, and even more preferably CH3.

[0032] The aforementioned Z is preferably a basis represented by F, -Q-Rf 1-Y, or a basis represented by the following formula: .

[0033] From the perspective of self-aggregation, Z in general formula (B 1) is preferably represented by -Q-Rf 1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-).

[0034] From the viewpoint of ease of synthesis of monomers, the above-mentioned Q is preferably a single bond, -O-(C=O)-, or -C(=O)-O-, more preferably -O-(C=O)-, or -C(=O)-O-, and even more preferably -C(=O)-O-.

[0035] From the viewpoint of the polymer's heat resistance and electrical properties, the number of carbon atoms in Rf 1 is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4. Rf 1 is preferably a fluorinated alkyl group without ether bonds between carbon atoms, more preferably a group represented by -CH 2-Rf 3-X 5 (Rf 3 is a straight-chain or branched fluorinated alkyl group with 1 to 19 carbon atoms, and X 5 is H or F). The number of carbon atoms in Rf 3 is preferably 1 to 9, more preferably 1 to 5, and even more preferably 1 to 3.

[0036] From the viewpoint of electrical properties, Y is preferably F, H, or -COOR (R is an alkyl group with 1 to 20 carbon atoms), more preferably H or F, and even more preferably F.

[0037] The hydrocarbon groups in X6 to X10 are preferably non-fluoroalkyl or fluoroalkyl. Furthermore, the number of carbon atoms in the hydrocarbon groups is preferably 1 to 6, and more preferably 1 to 4.

[0038] The fluorinated olefins mentioned above are preferably selected from at least one of the group consisting of fluorinated olefins with functional groups (1), fluorinated olefins without functional groups (2), and cyclic fluorinated olefins (3).

[0039] (1) Fluorinated olefins with functional groups The fluorinated olefin (1) with functional groups is preferably the monomer represented by the following formula (3): (In the formula, X11, X12, and X13 may be the same or different, and are H or F; X14 is H, F, or CF3; h is an integer from 0 to 2; i is 0 or 1; Rf4 is a fluorinated alkyl group with 1 to 40 carbon atoms or a fluorinated alkyl group with ether linkage with 2 to 100 carbon atoms; Z1 is a functional group selected from the group consisting of -OH, CH2OH, -COOH, carboxylic acid derivatives, -SO3H, sulfonic acid derivatives, epoxy groups, and cyano groups), wherein, more preferably, it is a monomer represented by CH2=CFCF2ORf4-Z1 (in the formula, Rf4 and Z1 are the same as above). More specifically, the following examples are preferred: (In the formula, Z1 is the same as above) and other monomers.

[0040] Furthermore, as a fluorinated olefin (1) with a functional group, the monomer represented by CF 2=CFORf 4-Z 1 (where Rf 4 and Z 1 are the same as above) can be preferably cited. More specifically, the following can be listed: (In the formula, Z1 is the same as above) and other monomers.

[0041] In addition, examples of fluorinated olefins (1) with functional groups include:

[0042] (In the formula, Rf 4 and Z 1 are the same as above) etc.

[0043] More specifically, examples include: (In the formula, Z1 is the same as above) etc. Among them, since monomers with -OH group, -COOH group, and -SO 3H group may reduce electrical properties, it is preferable to have an amount that does not reduce electrical properties.

[0044] As a fluorinated olefin with a functional group (1), the preferred ones are CH 2=CF-CF 2-O-(CF(CF 3)-CF 2) n-CF(CF 3)CH 2OH (where n=0~9), CH 2=CF-CF 2-O-(CF(CF 3)-CF 2) n-CF(CF 3)COOH (where n=0~9), CH 2=CF-CF 2-O-(CF(CF 3)-CF 2) n-CF(CF 3)CN (where n=0~9), or CF 2=CF-O-(CF 2CF(CF 3)O) n-(CF 2) mZ 3 (where Z 3 is COOH, SO 3H or CN, m=1~6, n=0~6).

[0045] (2) Fluorinated olefins without functional groups Fluoroolefins (2) without functional groups are better in terms of further improving electrical properties. Furthermore, by selecting this monomer, it is also better in terms of adjusting the mechanical properties or glass transition temperature of the polymer.

[0046] The fluorinated olefin (2) that does not contain any functional groups mentioned above is preferably represented by formula (4):

[0047]

[0048] (In the formula, X15, X16 and X18 are the same or different, and are H or F; X17 is H, F or CF3; h1, i1 and j are 0 or 1; Z2 is H, F or Cl; Rf5 is a fluorinated alkyl group with 1 to 20 carbons or a fluorinated alkyl group with 2 to 100 carbons containing ether linkage).

[0049] As specific examples, the following can be well listed: CH2=CH-(CF2)nF (n=1~10), CH2=CF-CF2-O-(CF(CF3)-CF2)n-CF(CF3)H (n=0~9). Monomers, etc. Among them, CF 2=CF 2, CF 2=CF-O-(CF 2) nF(n=1~5), CH 2=CF-CF 2-O-(CF(CF 3)-CF 2) n-CF(CF 3)H(n=0~5), CH 2=CH-(CF 2) nF(n=1~6), CF 2=CF-CF 3, CF 2=CFCl, or CF are preferred. 2=CH 2.

[0050] (3) Cyclic fluorinated olefins Cyclic fluorinated olefins (3) are superior in terms of further improving electrical properties, obtaining fluorinated hollow microparticles with high glass transition temperatures, and expecting further increases in hardness. Examples of cyclic fluorinated olefins (3) include monomers (3-1) having aliphatic cyclic structures and cyclizable diene monomers (3-2).

[0051] (3-1) Monomers with aliphatic cyclic structures The aforementioned monomer with an aliphatic cyclic structure (3-1) is a monomer in which at least one of the carbon atoms constituting the ring is a carbon atom constituting a carbon-carbon unsaturated double bond, and has an aliphatic cyclic structure. The aliphatic ring in the monomer with the aliphatic cyclic structure is preferably a ring with ether bonding, and more preferably a monomer without hydrogen atoms bonded to carbon atoms. The monomer with the aliphatic cyclic structure is a monomer in which double bonds are formed between adjacent carbon atoms constituting the ring (e.g., formulas (a), (c), (a-1) to (a-5) below), or a monomer in which double bonds are formed between carbon atoms constituting the ring and carbon atoms outside the ring (e.g., formulas (a-6), (a-7) below). [In the formula, R12~R15 independently represent a fluorine atom, a C1~C5 perfluoroalkyl group, or a C1~C5 perfluoroalkoxy group]. [In the formula, R16~R19 represent fluorine atoms, C1~C5 perfluoroalkyl groups, or C1~C5 perfluoroalkoxy groups, respectively].

[0052] The monomer (3-1) having an aliphatic cyclic structure is preferably selected from at least one of the groups composed of monomers represented by (a-1), (a-3), (a-6) and (a-7), and more preferably selected from at least one of the groups composed of monomers represented by (a-1), (a-3) and (a-7).

[0053] (3-2) Cyclic polymerizable diene monomers Cyclic polymerizable diene monomers (3-2) are also fluorinated diene monomers that can be cyclized. For example, monomers represented by formula (b) can be listed below: CF² = CF - Q¹ - CF = CF²...(b) [In the formula, Q1 can be a straight chain with 1 to 5 carbon atoms (preferably 1 to 3) or a branched perfluoroalkyl group, in which a portion of the fluorine atom can be replaced by a halogen atom other than the fluorine atom]. Examples of halogen atoms other than fluorine include: chlorine atoms, bromine atoms, etc.

[0054] Q1 above is preferably a perfluoroalkyl group having ether linkages. In this case, the ether linkage in the perfluoroalkyl group may exist at one end of the group, at both ends of the group, or between carbon atoms of the group. From the perspective of superior cyclic polymerization, it is preferred that it exists at one end of the group. Examples of monomers represented by formula (b) include: perfluoro(3-butenyl vinyl ether), perfluoro(allyl vinyl ether), perfluoro(3,5-dioxaheptadiene), perfluoro(3,5-dioxaheptadiene), etc. Perfluoro(3,5-dioxaheptadiene) is particularly preferred.

[0055] Furthermore, as a unit formed by the cyclization polymerization of the monomer represented by formula (b) above, examples can be listed as follows: formulas (II-1) to (II-4). As shown in the following formulas, for formulas (II-1) to (II-3), the four carbon atoms constituting two double bonds constitute the polymer backbone, and for formula (II-4), only the two carbon atoms at the ends of the two double bonds constitute the polymer backbone. Also, as in formula (II-1), two of the four carbon atoms constituting two double bonds can also form an aliphatic ring together with Q1, as in formulas (II-2) and (II-3), three double bonds can also form an aliphatic ring together with Q1, and as in formula (II-4), four double bonds can also form an aliphatic ring together with Q1. Furthermore, as an aliphatic ring containing Q1, it is easy to form 5-membered and 6-membered rings, and the polymer generated by cyclization polymerization is a polymer with 5-membered or 6-membered rings as the main unit.

[0056]

[0057] The fluorinated olefins mentioned above are preferably selected from at least one of the group consisting of fluorinated olefins (1) having functional groups, fluorinated olefins (2) without functional groups, and cyclic fluorinated olefins (3), more preferably selected from at least one of the group consisting of fluorinated olefins (2) without functional groups and cyclic fluorinated olefins (3), and even more preferably cyclic fluorinated olefins (3).

[0058] The fluorinated monomers mentioned above are preferably fluorinated styrene monomers represented by the following general formula: CX 1X 2=CY 1Z 1 (In the formula, X1, X2, and Y1 are independently H, CH3, F, or Cl, and Z1 is the basis represented by the following formula:) (In the formula, X6~X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1 to 8 carbon atoms that can be substituted by fluorine or chlorine), wherein any one of X1, X2, Y1 and Z contains more than one F). From the viewpoint of heat resistance, the hydrocarbon groups with 1 to 8 carbons that can be substituted by fluorine or chlorine are preferably hydrocarbon groups with 1 to 4 carbons that can be substituted by fluorine, more preferably hydrocarbon groups with 1 to 2 carbons that can be substituted by fluorine, and most preferably -CF3 or CH3. The fluorinated styrene monomers mentioned above are preferably selected from at least one of the group consisting of CH2=CH-C6F5, CF2=CF-C6H5, CH2=C(CH3)-C6F5, CF2=CF-C6H4-CH3, and CF2=CF-C6H4-CF3, and more preferably selected from at least one of the group consisting of CH2=CH-C6F5 and CF2=CF-C6H5.

[0059] The fluorinated monomer is preferably selected from at least one of the group consisting of fluorinated acrylic monomers, fluorinated styrene monomers, and fluorinated olefins, and more preferably a fluorinated acrylic monomer. For example, it is preferably selected from at least one of the group consisting of fluoroalkyl acrylates, fluoroalkyl methacrylates, fluoroalkyl 2-fluoroacrylates, and fluoroalkyl 2-chloroacrylates.

[0060] Furthermore, the aforementioned fluorinated monomer is preferably a fluorinated acrylic acid monomer represented by the following general formula (C1): CH 2=CX 3-COORf 2(C 1) (In the formula, X3 is H, CH3, F, Cl or CF3, and Rf2 is a fluorinated alkyl group with 1 to 20 carbon atoms that can contain ether bonds between carbon atoms).

[0061] From the perspective of polymerization properties, X3 is preferably H, CH3 or F; from the perspective of heat resistance, it is more preferably CH3 or F; and from the perspective of monomer stability, it is even more preferably CH3.

[0062] From the perspective of electrical properties and heat resistance, the carbon number of Rf2 is preferably 1 to 10, more preferably 2 to 8, and even more preferably 2 to 6.

[0063] Examples of the above-mentioned fluorinated acrylic monomers (C1) include: CH 2=C(CH 3)COOCH 2CF 3(3FM)、 CH 2=C(CH 3)COOCH 2CF 2CF 2H(4FM)、 CH 2=C(CH 3)COOCH 2CF 2CF 3(5FM)、 CH 2=C(CH 3)COOCH 2CF 2CFHCF 3(6FM)、 CH 2=C(CH 3)COOCH 2(CF 2) 3CF 2H(8FM)、 CH 2=C(CH 3)COOCH 2CH 2(CF 2) 3CF 3(9FM)、 CH 2=C(CH 3)COOCH 2(CF 2) 5CF 2H(12FM)、 CH 2=C(CH 3)COOCH 2CH 2(CF 2) 5CF 3(13FM)、 CH 2=C(CH 3)COOCH(CF 3) 2(HFIP-MA)、 CH 2=C(CH 3)COOCH 2CCH 3(CF 3) 2(6FNP-M)、 CH 2=C(CH 3)COOCH 2CF(CF 3)OCF 2CF 2CF 3(6FOn0-MA), Or corresponding to each of the acrylates, each of the 2-fluoroacrylates, and each of the 2-chloroacrylates.

[0064] Examples of the above-mentioned fluoroalkyl 2-fluoroacrylates include: CH 2=CFCOOCH 2CF 3(3FF) CH 2=CFCOOCH 2CF 2CF 2H(4FF)、 CH 2=CFCOOCH 2CF 2CF 3(5FF)、 CH 2=CFCOOCH 2(CF 2) 3CF 2H(8FF)、 CH 2=CFCOOCH 2CH 2(CF 2) 3CF 3(9FF)、 CH 2=CFCOOCH 2(CF 2) 5CF 2H(12FF)、 CH 2=CFCOOCH 2CH 2(CF 2) 5CF 3(13FF)、 CH 2=CFCOOCH(CF 3) 2(HFIP-F)、 CH 2=CFCOOCH 2CCH 3(CF 3) 2(6FNP-F) etc.

[0065] Examples of the above-mentioned fluoroalkyl 2-chloroacrylates include: CH 2=C(Cl)COOCH 2CH 2(CF 2) 3CF 3(9FCLA)、 CH 2=C(Cl)COOCH 2CH 2(CF 2) 5CF 3(13FCLA) etc.

[0066] Examples of the above-mentioned fluoroalkyl acrylates include: CH 2=CHCOOCH 2(CF 2) 3CF 2H(8FA)、 CH 2=CHCOOCH 2CH 2(CF 2) 3CF 3(9FA)、 CH 2=CHCOOCH 2(CF 2) 5CF 2H(12FA)、 CH 2=CHCOOCH 2CH 2(CF 2) 5CF 3(13FA)、 CH 2=CHCOOCH(CF 3) 2(HFIP-A)、 CH 2=CHCOOCH 2CCH 3(CF 3) 2(6FNP-A) etc.

[0067] From the viewpoint of heat resistance and electrical properties, the aforementioned fluorinated monomer is preferably a fluorinated olefin, more preferably at least one of the monomers selected from the group consisting of monomers represented by (a-1), (a-3), (a-6) and (a-7), and even more preferably at least one of the monomers selected from the group consisting of monomers represented by (a-1), (a-3) and (a-7).

[0068] The aforementioned fluorinated monomer preferably has a fluorine content of 30% by mass or more. According to the manufacturing method of the present invention, even when using a fluorinated monomer with a fluorine content of 30% by mass or more, hollow microparticles with a large average particle size can be manufactured. The fluorine content of the fluorinated monomer is more preferably 40% by mass or more, and even more preferably 50% by mass or more. Furthermore, there is no particular upper limit to the fluorine content; the fluorine content can be 80% by mass, preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0069] As the aforementioned fluorinated monomer, it is particularly preferred to be at least one selected from the group consisting of 3FM, 5FM, 13FM, HFIP-A, HFIP-MA, HFIP-F, 3FF, 5FF, 13FF, 6FNP-A, 6FNP-M, and 6FNP-F, and even more preferably to be at least one selected from the group consisting of 3FM, 5FM, 13FM, 3FF, 5FF, 13FF, HFIP-MA, HFIP-F, and HFIP-A.

[0070] The solution containing the fluorinated monomer, phase separation promoter and non-polymerizable solution preferably also contains monomers capable of copolymerizing with the fluorinated monomer.

[0071] Examples of monomers that can copolymerize with fluorinated monomers include: crosslinking monomers and fluorine-free monomers (excluding crosslinking monomers).

[0072] Examples of crosslinking monomers include: polyfunctional monomers having polymerizable reactive groups, especially those having two or more (particularly two to four) polymerizable double bonds. Using polyfunctional monomers can enhance the strength of the obtained hollow microparticles. The solution described above preferably contains the crosslinking monomer.

[0073] Examples of the aforementioned multifunctional monomers include: ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, etc.; trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, neopentyltetrol tri(meth)acrylate, etc.; neopentyltetrol tetra(meth)acrylate, dinepentyltetrol hexa(meth)acrylate, diallyl phthalate, diallyl malate, diallyl transbutenedioic acid, diallyl succinate, triallyl isocyanate, etc., diallyl or triallyl compounds; divinylbenzene, butadiene, etc., divinyl compounds, etc. Preferably, it is selected from at least one of the groups consisting of di(meth)acrylate, tri(meth)acrylate, and divinyl compounds, and more preferably from at least one of the groups consisting of ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and divinylbenzene. These can be used alone or in combination of two or more. Furthermore, from the perspective of improving electrical properties, it is also preferable that a portion of the aforementioned polyfunctional acrylate monomers is a fluorinated polyfunctional acrylate monomer that has been replaced by fluorine. Examples of fluorinated polyfunctional acrylate monomers include: ethylene glycol diα-fluoroacrylate, diethylene glycol diα-fluoroacrylate, triethylene glycol diα-fluoroacrylate, 1,6-hexanediol diα-fluoroacrylate, trimethylolpropane diα-fluoroacrylate, etc.; trimethylolpropane triα-fluoroacrylate, ethylene oxide-modified trimethylolpropane triα-fluoroacrylate, neopentyltetrafluoroacrylate, etc.; neopentyltetrafluoroacrylate, dinepentyltetrafluoroacrylate, CH 2=CX-COO-CH 2(CF 2CF 2) nCH 2-OCO-CX=CH 2 (where X is H, CH 3, F, or Cl, n=1~10), CH 2=CX-COO-CH 2CF(CF 3)-O-(CF 2CF(CF 3)O) nCF(CF 3)CH 2-OCO-CX=CH 2 (Here, X is H, CH3, F, or Cl, n=1~20), etc. Also, examples can be listed as follows: CF2=CF-O-(CF2)nO-CF=CF2 (where n=1~20), CF2=CF-(O-CF2CF(CF3))nO-CF=CF2 (where n=1~20), CF2=CF-(CF2)n-CF=CF2 (where n=1~20), etc.

[0074] There are no particular limitations on the above-mentioned non-fluorine monomers (excluding cross-linking monomers), but examples include: monofunctional monomers that do not contain fluorine atoms but have one polymerizable reactive group. Examples of the aforementioned monofunctional monomers include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cumyl methacrylate, cyclohexyl methacrylate, myristyl methacrylate, palmitate methacrylate, stearyl methacrylate, lauryl methacrylate, isoborneol methacrylate, and other alkyl methacrylates; methacrylonitrile, acrylamide, methacrylic acid, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and other methacrylate monomers containing polar groups; styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and other aromatic vinyl monomers; vinyl acetate, vinyl benzoate, vinyl neononanoate (trade name Veova 9), vinyl neodecanoate (trade name Veova 9). 10) Vinyl esters such as vinyl propionate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and hydroxybutyl vinyl ether; halogenated monomers such as vinyl chloride and vinylidene chloride; vinylpyridine, 2-acryloyloxyethyl phthalate, itconic acid, fumaric acid, ethylene, propylene, and polydimethylsiloxane macromonomers. From the viewpoint of compatibility with fluorinated monomers or improving Tg, at least one monomer selected from the group consisting of methyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, and isoborneol methacrylate is preferred.

[0075] Regarding the above solution, the monomer content is preferably 0.1 to 10 parts by mass relative to 1 part by mass of the above non-polymerizable solvent, more preferably 0.5 to 5 parts by mass, and even more preferably 0.8 to 3.5 parts by mass. Furthermore, regarding the content of the aforementioned monomers, when only fluorinated monomers are polymerized, it refers to the amount of fluorinated monomers used; when polymerizing fluorinated monomers and monomers that can copolymerize with fluorinated monomers, it refers to the total amount of fluorinated monomers and monomers that can copolymerize with fluorinated monomers. In the above solution, the ratio of fluorinated monomers and monomers that can copolymerize with fluorinated monomers (crosslinking monomers and non-fluorinated monomers) can be appropriately set according to the target fluorinated resin.

[0076] The phase separation promoters mentioned above are not particularly limited as long as they can promote phase separation in the polymerization step, but are preferably polymers, and preferably have a weight average molecular weight of 3000 or more. The above weight-average molecular weight can be calculated by converting the PS weight-average molecular weight in the GPC determination.

[0077] The aforementioned phase separation accelerator is preferably soluble in a non-polymerizable solvent at room temperature (e.g., 25°C), and when the Sp value of the phase separation accelerator is set to SA (J / cm³)¹ / ², and the Sp value of the non-polymerizable solvent is set to SB (J / cm³)¹ / ², the following formula is satisfied: Compounds with a relationship of |SA-SB| < 3 (J / cm 3) 1 / 2. The aforementioned phase separation promoter is preferably one in which |SA-SB| is less than 2, and more preferably less than 1.

[0078] Examples of phase separation promoters include: aromatic vinyl polymers, poly(meth)acrylates, vinyl chloride polymers, polyvinyl acetate, polyesters, etc.

[0079] Examples of aromatic ethylene polymers include polystyrene, divinylbenzene, and acrylonitrile-styrene resins, with polystyrene being particularly preferred.

[0080] Examples of the aforementioned poly(meth)acrylates include: polymethyl methacrylate, polybutyl methacrylate, polyethyl methacrylate, etc., with polymethyl methacrylate being particularly preferred.

[0081] From the viewpoint of self-dissolution and hydrophobicity, the aforementioned phase separation promoter is preferably a polymer comprising polymerization units based on monomers represented by the following general formula: CH 2=CX 4Y 2 (In the formula, X4 is H, CH3, F, Cl, or CF3, Y2 is Cl, C6H4R1, C6H3R2R3, COOR4, or OCOR5 (here, R1, R2, R3, R4 and R5 are independently H, OH, or alkyl groups with 1 to 40 carbon atoms that can be substituted by halogen atoms)).

[0082] Regarding the above solution, the content of the phase separation promoter is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0.3 parts by mass, and even more preferably 0.05 to 0.2 parts by mass, relative to 1 part by mass of the above non-polymerizable solvent.

[0083] The solution described above preferably contains an initiator. The initiator may be added to the solution before the dispersion step, or it may be added to the dispersion after the dispersion step and before the polymerization step.

[0084] Examples of initiators include: oil-soluble initiators, and those that initiate the polymerization of fluorinated monomers (or fluorinated monomers and monomers capable of copolymerizing with fluorinated monomers) in droplets formed by dispersing the above solution in water, which are those previously used. Examples of free radical polymerization initiators include azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), and 2,2'-azobis(N-butyl-2-methylpropionic acid), as well as monomers soluble in peroxides such as cumene hydroperoxide, tributyl hydroperoxide, diisopropylphenyl peroxide, di(tributyl) peroxide, benzoyl peroxide, and lauryl peroxide. Alternatively, photopolymerization initiators that begin polymerization under light such as ultraviolet light can also be used. There are no particular limitations on the type of photopolymerization initiator used; previously used initiators can be employed. As the above-mentioned initiator, it is preferably selected from at least one of the group consisting of azo compounds, preferably an azo compound, wherein it is preferably selected from at least one of the group consisting of 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile) and azobisisobutyronitrile, more preferably 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile).

[0085] As the aforementioned non-polymerizable solvent, a solvent capable of dissolving fluorinated monomers, phase separation promoters, and, as needed, monomers and initiators that can copolymerize with fluorinated monomers, can be used, and which has low compatibility with the obtained fluorinated resin. By having low compatibility with the obtained fluorinated resin, phase separation of the obtained fluorinated resin is promoted, thereby enabling the manufacture of hollow microparticles. As a non-polymerizable solvent, it is preferably a solvent that can dissolve fluorinated monomers, phase separation promoters, and monomers and initiators that can copolymerize with fluorinated monomers as needed, without dissolving the obtained fluorinated resin.

[0086] As the aforementioned non-polymerizable solvent, a solvent that has low compatibility with the aforementioned fluorinated resin, and in the relationship between the surface tension (γX) between the non-polymerizable solvent and water, and the surface tension (γP) (mN / m) between the polymer adsorption surface obtained by dissolving the fluorinated monomer (and, if necessary, a monomer capable of copolymerizing with the fluorinated monomer) in the non-polymerizable solvent under the conditions of the manufacturing method of the present invention, is supplied to the polymer adsorption surface obtained by polymerization.

[0087] As a non-polymerizable solvent, it is preferably liquid at the polymerization temperature of the monomer (fluorinated monomer, or fluorinated monomer and monomer capable of copolymerizing with fluorinated monomer), and can be mixed with the monomer, does not react with the monomer, and can be easily evaporated by heating, etc. It is preferably selected from at least one of the group consisting of aromatic hydrocarbons, esters, or saturated hydrocarbons, or halogenated substitutes of such hydrocarbons. Examples of the above-mentioned saturated hydrocarbons and their halogenated substitutes include: butane, pentane, hexane, hexadecane, cyclohexane, decane, chloromethane, dichloromethane, chloroform, carbon tetrachloride, bromonaphthalene, dichloromethane, etc. Examples of aromatic hydrocarbons mentioned above include toluene, xylene, benzene, and chlorobenzene. Examples of the aforementioned esters include ethyl acetate and butyl acetate. Furthermore, fluorinated solvents such as fluorinated alkanes, fluorinated haloalkanes, fluorinated aromatic compounds, and fluorinated ethers (e.g., hydrofluoroethers (HFE)) are preferred, provided they have low compatibility with fluorinated resins. For example, perfluorohexane, 1,3-trifluoromethylbenzene, perfluorotriheptylamine, and perfluorotributylamine are preferred.

[0088] The fluorinated solvent is preferably selected from at least one of perfluoroaromatic compounds, perfluorotrialkylamines, perfluoroalkanes, hydrofluorocarbons, perfluorocyclic ethers, and hydrofluoroethers. These fluorinated solvents are particularly preferably fluorinated olefins, especially when using PF-MMD.

[0089] The aforementioned perfluoroaromatic compounds may include, for example, perfluoroaromatic compounds having one or more perfluoroalkyl groups. The aromatic rings of the perfluoroaromatic compound may be at least one selected from the group consisting of benzene rings, naphthalene rings, and anthracene rings. Perfluoroaromatic compounds may also have one or more aromatic rings (e.g., one, two, or three). The perfluoroalkyl group used as a substituent is, for example, a straight-chain or branched C1-C6, C1-C5, or C1-C4 perfluoroalkyl group, preferably a straight-chain or branched C1-C3 perfluoroalkyl group. The number of substituents is, for example, 1 to 4, preferably 1 to 3, more preferably 1 to 2. When multiple substituents are present, they may be the same or different. Examples of perfluoroaromatic compounds include perfluorobenzene, perfluorotoluene, perfluoroxylene, and perfluoronaphthalene. Preferred examples of perfluoroaromatic compounds include perfluorobenzene and perfluorotoluene.

[0090] The aforementioned perfluorotrialkylamines are, for example, amines substituted with three straight-chain or branched perfluoroalkyl groups. The number of carbon atoms in the perfluoroalkyl group is, for example, 1 to 10, preferably 1 to 5, and more preferably 1 to 4. The perfluoroalkyl group may be the same or different, but is preferably the same. Examples of perfluorotrialkylamines include: perfluorotrimethylamine, perfluorotriethylamine, perfluorotripropylamine, perfluorotriisopropylamine, perfluorotributylamine, perfluorotri(secondary butylamine), perfluorotri(tertiary butylamine), perfluorotripentylamine, perfluorotriisopentylamine, and perfluorotrinepentylamine, preferably perfluorotripropylamine or perfluorotributylamine.

[0091] The aforementioned perfluoroalkanes are, for example, straight-chain, branched, or cyclic C3-C12 (preferably C3-C10, more preferably C3-C6) perfluoroalkanes. Examples of perfluoroalkanes include: perfluoropentane, perfluoro-2-methylpentane, perfluorohexane, perfluoro-2-methylhexane, perfluoroheptane, perfluorooctane, perfluorononane, perfluorodecane, perfluorocyclohexane, perfluoro(methylcyclohexane), perfluoro(dimethylcyclohexane) (e.g., perfluoro(1,3-dimethylcyclohexane)), perfluorodecahydronaphthalene, preferably perfluoropentane, perfluorohexane, perfluoroheptane, or perfluorooctane.

[0092] The aforementioned hydrofluorocarbons are, for example, C3-C8 hydrofluorocarbons. Examples of hydroperfluorocarbons include: CF3CH2CF2H, CF3CH2CF2CH3, CF3CHFCHFC2F5, 1,1,2,2,3,3,4-heptafluorocyclopentane, CF3CF2CF2CF2CH2CH3, CF3CF2CF2CF2CF2CF2CHF2, CF3CF2CF2CF2CF2CF2CH2CH3, preferably CF3CH2CF2H or CF3CH2CF2CH3.

[0093] The aforementioned perfluorocyclic ethers may be, for example, perfluorocyclic ethers having one or more perfluoroalkyl groups. The rings in the perfluorocyclic ethers may be 3- to 6-membered rings. Regarding the rings in the perfluorocyclic ethers, as ring-forming atoms, one or more oxygen atoms may be present. Preferably, the ring has one or two oxygen atoms, more preferably one oxygen atom. The perfluoroalkyl group as a substituent is, for example, a straight-chain or branched C1-C6, C1-C5, or C1-C4 perfluoroalkyl group. Preferably, the perfluoroalkyl group is a straight-chain or branched C1-C3 perfluoroalkyl group. The number of substituents is, for example, 1 to 4, preferably 1 to 3, more preferably 1 to 2. When multiple substituents are present, they may be the same or different. Examples of perfluorocyclic ethers include perfluorotetrahydrofuran, perfluoro-5-methyltetrahydrofuran, perfluoro-5-ethyltetrahydrofuran, perfluoro-5-propyltetrahydrofuran, perfluoro-5-butyltetrahydrofuran, and perfluorotetrahydropyran. Preferred examples of perfluorocyclic ethers include perfluoro-5-ethyltetrahydrofuran and perfluoro-5-butyltetrahydrofuran.

[0094] The aforementioned hydrofluoroethers are, for example, fluorinated ethers. The global warming potential (GWP) of hydrofluoroethers is preferably below 400, and more preferably below 300. Examples of hydrofluoroethers include: CF 3CF 2CF 2CF 2OCH 3, CF 3CF 2CF(CF 3)OCH 3, CF 3CF(CF 3)CF 2OCH 3, CF 3CF 2CF 2CF 2OC 2H 5, CF 3CH 2OCF 2CHF 2, C 2F 5CF(OCH 3)C 3F 7, trifluoromethyl-1,2,2,2-tetrafluoroethyl ether (HFE-227me), difluoromethyl-1,1,2,2,2-pentafluoroethyl ether (HFE-227mc), trifluoromethyl-1,1,2,2-tetrafluoroethyl ether (HFE-227pc), difluoromethyl-2,2,2-trifluoroethyl ether (HFE-245mf), and 2,2-difluoroethyltrifluoromethyl ether (HFE-245pf). As hydrofluoroethers, the preferred compounds are those represented by the following formula (D1): CF 3CH 2OCF 2CHF 2, C 2F 5CF(OCH 3)C 3F 7, or CF 3CF 2CF 2CF 2OCH 3, CF 3CF 2CF 2CF 2OC 2H 5. R 21-OR 22(D1) [In the formula, R 21 is a straight-chain or branched perfluorobutyl, and R 22 is a methyl or ethyl], more preferably a compound represented by the above formula (D1).

[0095] From the viewpoint of manufacturing hollow microparticles with a single-pore structure, the non-polymerizable solvent is preferably selected from at least one of the group consisting of aromatic hydrocarbons, esters, or saturated hydrocarbons having 8 to 18 carbon atoms, or halogenated derivatives thereof, and more preferably from at least one of the group consisting of toluene and xylene, with toluene being particularly preferred.

[0096] In the manufacturing method of this invention, a monoporous structure or a porous structure can be achieved by changing the type of non-polymerizable solvent. The reason for becoming a porous structure or a monoporous structure is not yet clear, but in the combination of the generated fluorinated resin and solvent, a completely incompatible system becomes a monoporous structure, while a slightly compatible system exhibits a porous structure. A completely incompatible system is defined as one in which the fluorinated resin produced is 5% by mass in a non-polymerizing solvent, and after 6 hours at the polymerization temperature, it is visually confirmed that the system does not swell. For example, by using the aforementioned saturated hydrocarbons as non-polymerizing solvents, hollow microparticles with a single-pore structure can be manufactured.

[0097] The amount of the aforementioned non-polymerizable solvent can be appropriately selected from a wide range. Generally speaking, it is set to 0.1 to 10 parts by mass relative to 1 part by mass of the monomer (i.e., fluorinated monomer, or fluorinated monomer and monomer that can copolymerize with fluorinated monomer), preferably 0.5 to 5 parts by mass.

[0098] The solution is preferably a dispersion stabilizer, which can further promote phase separation and obtain hollow microparticles with large particle size.

[0099] As the aforementioned dispersion stabilizer, those that prevent droplets from condensing can be widely used, where the droplets are formed by dispersing a solution containing monomer components, phase separation promoters, and non-polymerizing solvents in water.

[0100] Examples include: polyvinyl alcohol, methylcellulose, ethylcellulose, polyacrylic acid, polyacrylamide, polyethylene oxide, poly(hydroxystearic acid-g-methyl methacrylate-copolymer-methacrylic acid) copolymers, and other polymeric dispersion stabilizers, nonionic surfactants, anionic surfactants, and amphoteric surfactants. Polyvinyl alcohol and other polymeric dispersion stabilizers are preferred. Fluorinated anionic surfactants may also be used.

[0101] The content of the dispersant stabilizer is preferably 0.005 to 1 part by mass relative to 1 part by mass of the above solution, and more preferably 0.01 to 0.1 parts by mass.

[0102] The above dispersion step involves dispersing a solution containing fluorinated monomers, phase separation promoters, non-polymerizable solvents, and, as needed, monomers that can copolymerize with fluorinated monomers, initiators, dispersion stabilizers, etc., in water to obtain a dispersion. Various known methods can be used for dispersion, such as dispersion by mechanical shear force, such as homogenization or membrane emulsification. The temperature conditions during dispersion can be above 0°C but not exceeding 100°C, preferably 0~90°C. When the solution contains an initiator in the dispersion step, the temperature should be below the temperature that affects the decomposition of the initiator used, usually below room temperature, and preferably around 0~30°C.

[0103] In the above dispersion method, the droplets formed by dispersing the solution are not monodisperse, but generally consist of droplets of various sizes. Therefore, the hollow microparticles obtained in the end also have different particle sizes. On the other hand, by selecting a dispersion method, it is also possible to obtain monodisperse droplets with uniform droplet size. For example, a method for obtaining such monodisperse droplets can be described using a membrane emulsification method with porous glass (SPG). In the case of preparing such monodisperse droplets with uniform particle size, the resulting hollow microparticles also become monodisperse with uniform particle size. In any case, the average particle size of the droplets can be appropriately determined based on the desired average particle size of the hollow microparticles.

[0104] The aforementioned dispersion step is preferably dispersion step A, 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 dispersion step B, in which the solution is dispersed in water at a temperature not exceeding 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). By employing the above steps, even when the fluorine content of the fluorinated monomer is high, the dispersion will not separate, allowing polymerization to proceed efficiently.

[0105] The manufacturing method of the present invention is also preferably performed after the dispersion step and before the polymerization step, further including the step of adding an oil-soluble initiator to the dispersion. When the dispersion step is carried out at a relatively high temperature (e.g., above 50°C) as described above, if the initiator is added to the solution beforehand, there is a risk that polymerization may begin during the dispersion step. Therefore, by adding the initiator to the dispersion after the dispersion step and before the polymerization step, the dispersion step can also be carried out at a relatively high temperature.

[0106] The above dispersion step can be any step that polymerizes at least the fluorinated monomer, or it can be any step that polymerizes only the fluorinated monomer, or it can be any step that polymerizes the fluorinated monomer and the monomers that can copolymerize with the fluorinated monomer as described above.

[0107] The polymerization step described above can be performed using methods known previously, such as microemulsion polymerization, fine emulsion polymerization, and microsuspension polymerization. The polymerization in the above step can also be suspension polymerization; to supply the dispersion containing the above solution to the suspension polymerization process, simply stir the dispersion and simultaneously heat it.

[0108] As for the polymerization temperature, there is no particular limitation as long as it is sufficient to induce polymerization of the above-mentioned fluorinated monomers (and monomers that can copolymerize with the fluorinated monomers as needed) by the initiator. Generally speaking, it is 10~90℃, and preferably 30~80℃.

[0109] The polymerization proceeds until the desired hollow microparticles are obtained. The time required for polymerization varies depending on the type of fluorinated monomer used (and, if necessary, monomers that can copolymerize with the fluorinated monomer), polymerization initiator, and non-polymerizing solvent, and is generally about 3 to 24 hours.

[0110] Furthermore, polymerization is preferably carried out in an inert gas environment such as nitrogen or argon.

[0111] In this manner, the fluorinated monomer (or the fluorinated monomer and the monomer capable of copolymerizing with the fluorinated monomer) is polymerized in a droplet of solution containing a fluorinated monomer (or a fluorinated monomer and a monomer capable of copolymerizing with the fluorinated monomer), a phase separation promoter and a non-polymerizing solvent. Regarding the obtained copolymer, phase separation is promoted by the presence of a phase separation promoter and a non-polymerizing solvent, resulting in the formation of a single-layer shell, i.e., a shell containing a fluorinated resin, which contains polymeric units based on fluorinated monomers (or polymeric units based on fluorinated monomers and monomers capable of copolymerizing with fluorinated monomers). On the other hand, the core, which is the hollow part, becomes a state in which a non-polymerizing solvent is encapsulated.

[0112] Hollow microparticles obtained in this way can be used directly as a dispersion, or they can be filtered and washed with water as needed before being supplied to various applications in powder form. Furthermore, hollow microparticles in the form of a dispersion or powder, having removed the non-polymerizable solvent, can be supplied to various applications. Therefore, the method for manufacturing hollow microparticles of the present invention preferably includes a removal step of removing the aforementioned non-polymerizable solvent from the obtained hollow microparticles. The removal process is not particularly limited as long as it removes the non-polymerizable solvent present in the hollow portion. Examples include: heating the hollow microparticles containing the non-polymerizable solvent within the hollow portion, allowing the non-polymerizable solvent to evaporate naturally, and depressurization. From the perspective of simplicity and economy, removal by heating is preferred. The heating temperature can be appropriately set according to the type of non-polymerizable solvent, and it is preferably carried out under conditions of approximately 20-300°C and 1-100,000 Pa.

[0113] Furthermore, in this invention, the term "hollow" in hollow microparticles does not only refer to the presence of air in the hollow portion, but also includes the presence of the aforementioned non-polymerizable solvents in the hollow portion.

[0114] With the above-described structure, the manufacturing method of the present invention can produce hollow microparticles with an average particle size of 1.0 μm or more. 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 above-mentioned average particle size is preferably 50.0 μm or less, and more preferably 30.0 μm or less. The average particle size mentioned above can be determined using the DLS (Dynamic Light Scattering) method. Alternatively, it can be calculated from optical microscope images using particle size analysis software such as LUZEX AP. In this case, it is ideal to take multiple images with a total particle count of 50 or more for analysis. Furthermore, the manufacturing method of the present invention can manufacture the hollow microparticles of the present invention as shown below.

[0115] The hollow microparticles of this invention contain a fluorinated resin D comprising a polymer unit based on a fluorinated monomer, and have an average particle size of 1.0 μm or more. The hollow microparticles of this invention may also have a nested structure, preferably consisting of a shell containing the fluorinated resin D and a hollow portion, and have a monoporous structure. Furthermore, in this specification, the term "monoporous structure" does not refer to a structure with multiple pores like a porous material, but rather to a structure with only one closed pore. Also, in the following description, the portion of the hollow microparticle other than the pores is referred to as the "shell".

[0116] In the above manufacturing method, the particle size of the hollow microparticles of the present invention can be adjusted by changing the size of the droplets. However, in conventional methods, it is difficult to increase the average particle size of hollow microparticles containing fluorinated resin. By using the manufacturing method of the present invention described above, even hollow microparticles containing fluorinated resin can have an increased average particle size, and hollow microparticles with an average particle size of 1.0 μm or more can be manufactured.

[0117] The hollow microparticles of the present invention preferably have an average particle size of 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 5.0 μm or more. Furthermore, 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. The average particle size mentioned above can be determined using the DLS (Dynamic Light Scattering) method. Alternatively, it can be calculated from optical microscope images using particle size analysis software such as LUZEX AP. In this case, it is ideal to take multiple images with a total particle count of 50 or more for analysis.

[0118] The hollow microparticles of the present invention are preferably composed of a shell containing fluorinated resin D and a hollow portion, and have a monopore structure. The pore size of the hollow portion is preferably 66-95% relative to the diameter of the hollow microparticles, and more preferably 66% or more, further preferably 74% or more, and even more preferably 79% or more. Furthermore, it is preferably 95% or less, more preferably 93% or less, further preferably 90% or less, and even more preferably 88% or less. The pore size of the hollow portion can be calculated by analyzing TEM images of the hollow microparticles using the particle size analysis software LUZEX AP. Specifically, approximately 200 hollow microparticles can be randomly selected from the TEM image, and the pore size of the hollow portion can be calculated using the following formula by measuring the inner radius (R1). Hollow section aperture = R1 × 2

[0119] In this invention, the hollow microparticles preferably have a shell thickness that is 17% or less in ratio to the diameter of the hollow microparticle. More preferably, this ratio is 13% or less, even more preferably 10% or less, and most preferably 9% or less. A thinner shell results in a higher porosity, thus allowing the production of hollow microparticles with a lower dielectric constant. From the perspective of the strength of hollow microparticles, the above ratio is preferably 4% or more, and more preferably 6% or more. The thickness of the shell can be calculated by analyzing TEM images of hollow microparticles using the particle size analysis software LUZEX AP. Specifically, approximately 200 hollow microparticles can be randomly selected from the TEM image, and the shell thickness can be calculated using the following formula by measuring the inner radius (R1) and outer radius (R2). Shell thickness = R2 - R1

[0120] The hollow microparticles of this invention preferably have a porosity of 30% by volume or more. More preferably, the porosity is 40% by volume or more, further preferably 50% by volume or more, and even more preferably 55% by volume or more. A higher porosity allows for a lower relative permittivity of the hollow microparticles, making them more suitable for use in electrical materials. There is no particular upper limit to the porosity, but from the viewpoint of the strength of the hollow microparticles, it is preferably 80% by volume or less, and more preferably 70% by volume or less. The porosity mentioned above can be calculated by analyzing TEM images of hollow microparticles using the particle size analysis software LUZEX AP. Specifically, approximately 200 hollow microparticles can be randomly selected from the TEM image, and the porosity can be calculated using the following formula by measuring the inner radius (R1) and outer radius (R2). Porosity (%) = (R1 / R2) 3 × 100

[0121] The hollow microparticles of this invention preferably have a refractive index of 1.40 or less. More preferably, the refractive index is 1.35 or less, even more preferably 1.30 or less, and particularly preferably 1.25 or less. The lower limit of the refractive index is not particularly limited; for example, it can be 1.10 or more. The refractive index mentioned above was obtained by the liquid immersion method.

[0122] The aforementioned fluorinated resin D may be composed solely of polymerization units based on fluorinated monomers, or it may include polymerization units based on fluorinated monomers and polymerization units based on monomers capable of copolymerizing with fluorinated monomers. Examples of monomers that can copolymerize with fluorinated monomers include: the aforementioned crosslinking monomers and fluorine-free monomers (excluding crosslinking monomers).

[0123] Since the shell of the hollow microparticles can be made robust, the aforementioned fluorinated resin D preferably comprises polymerization units based on fluorinated monomers and polymerization units based on crosslinking monomers. Because the shell of the hollow microparticles becomes robust, the shell thickness can be reduced, thereby increasing the porosity.

[0124] As the aforementioned crosslinking monomer, those exemplified in the manufacturing method of the present invention are preferably multifunctional monomers having two or more polymerizable double bonds, more preferably ethylene glycol di(meth)acrylate, divinylbenzene, and even more preferably ethylene glycol di(meth)acrylate.

[0125] Regarding the aforementioned fluorinated resin D, the polymeric unit based on the aforementioned crosslinking monomer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more, relative to all polymeric units. Furthermore, it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. By using polymeric units based on crosslinking monomers within the above range, the obtained hollow microparticles can be made to have excellent strength and excellent electrical properties.

[0126] In the aforementioned fluorinated resin D, the polymeric unit based on the fluorine-free monomer is preferably 0-70% by mass, and more preferably 0-50% by mass, relative to all polymeric units.

[0127] The aforementioned fluorinated resin D preferably has a fluorine content of 15% by mass or more. With a fluorine content of 15% by mass or more, the electrical properties and water resistance are superior. More preferably, the fluorine content is 30% by mass or more, and even more preferably 50% by mass or more. Hollow microparticles containing this fluorinated resin D and with an average particle size of 1.0 μm or more can be obtained by the manufacturing method of the present invention, particularly by a manufacturing method in which the dispersion step is dispersion step A or dispersion step B.

[0128] In the above-mentioned fluorinated resin D, monomers that are the same as those used in the manufacturing method of the present invention can be listed as fluorinated monomers, crosslinking monomers, and non-fluorinated monomers (excluding crosslinking monomers).

[0129] In the above-mentioned fluorinated resin D, examples of fluorinated monomers include: fluorinated acrylic monomers, fluorinated styrene monomers, fluorinated olefins, etc., without particular limitation, but preferably the monomer represented by the following general formula (B2): CX 1X 2=CY 1Z (B 2) (In the formula, X1, X2, and Y1 are independently the same or different, and are H, CH3, F, or Cl; Z is F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms)) and the group represented by the following formula: (In the formula, X6~X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1 to 8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein any one of X1, X2, Y1 and Z contains more than one F). As for X1, X2, Y1 and Z in the general formula (B2), it is preferable to use the same X1, X2, Y1 and Z as in the above general formula (B1).

[0130] In the above-mentioned fluorinated resin D, the fluorinated monomer is preferably a fluorinated acrylic monomer (C2) represented by the following general formula (C2): CH₂=CX₃-COORf₂(C₂) (In the formula, X3 is H, CH3, F, Cl or CF3, and Rf2 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms). As for X3 and Rf2 in the general formula (C2), it is preferable to use the same X3 and Rf2 as in the above general formula (C1). As the fluorinated acrylic monomer (C2) mentioned above, those identical to the fluorinated acrylic monomer (C1) in the manufacturing method of the present invention can be listed.

[0131] The fluorinated monomers mentioned above are preferably selected from at least one of the group consisting of 3FM, 5FM, 13FM, HFIP-A, 3FF, 5FF, 13FF, HFIP-MA, and HFIP-F, and more preferably selected from at least one of the group consisting of 3FM, 5FM, 13FM, HFIP-MA, and HFIP-A.

[0132] The aforementioned fluoropolymer D is preferably a polymer comprising: a fluorinated acrylic monomer (C2) and a crosslinking monomer (E) based on at least one of the groups selected from di(meth)acrylate, tri(meth)acrylate and divinyl compounds. Regarding the aforementioned fluorinated resin D, the mass ratio of the polymerization unit (C2) based on the aforementioned fluorinated monomer (C2) to the polymerization unit based on the aforementioned crosslinking monomer (E) (fluorinated monomer (C2) / crosslinking monomer (E)) is preferably 80 / 20 to 20 / 80 (mass ratio), more preferably 70 / 30 to 30 / 70 (mass ratio), and even more preferably 60 / 40 to 40 / 60 (mass ratio).

[0133] From the viewpoint of heat resistance and electrical properties, the aforementioned fluorinated monomer is preferably a fluorinated olefin, preferably selected from at least one of the group consisting of fluorinated olefins (1) with functional groups, fluorinated olefins (2) without functional groups, and cyclic fluorinated olefins (3), more preferably selected from at least one of the group consisting of fluorinated olefins (2) without functional groups and cyclic fluorinated olefins (3), and even more preferably cyclic fluorinated olefins (3). Furthermore, as a cyclic fluorinated olefin (3), it is preferably selected from at least one of the group consisting of monomers represented by (a-1), (a-3), (a-6), and (a-7) above, more preferably selected from at least one of the group consisting of monomers represented by (a-1), (a-3), and (a-7) above.

[0134] The fluorinated resin D mentioned above preferably has a relative permittivity (1 kHz) of 5.0 or less. More preferably, the relative permittivity is 4.0 or less, further preferably 3.7 or less, and even more preferably 3.5 or less. The lower limit of the relative permittivity is not particularly limited; for example, it can be 1.1 or more. The relative permittivity mentioned above was determined by means of the determination method according to JIS C 2138.

[0135] The aforementioned fluorinated resin D preferably has a refractive index of 1.40 or less. More preferably, the refractive index is 1.39 or less, and even more preferably 1.38 or less. There is no particular limitation on the lower limit of the refractive index; for example, it can be 1.30 or more. From the viewpoint of solubility in non-polymerizable solvents, it is preferably 1.35 or more. The refractive index mentioned above was obtained by the liquid immersion method.

[0136] The hollow microparticles of the present invention preferably contain a phase separation promoter. Examples of phase separation promoters described in the above-described method for manufacturing hollow microparticles include those described in the invention. By using the above-described method for manufacturing hollow microparticles, hollow microparticles containing a phase separation promoter can be obtained. The phase separation promoter is contained within the shell of the hollow microparticle. The content of the phase separation promoter, relative to fluorinated resin D, is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Compared to fluorinated resins, the content of the above-mentioned phase separation promoter can be 1% by mass or more, or 5% by mass or more.

[0137] In the hollow microparticles of the present invention, from the viewpoint of low dielectric properties and low refractive index, the hollow part is preferably a gas, and more preferably air.

[0138] The hollow microparticles of this invention, being hollow, exhibit excellent low dielectric constant and high-frequency characteristics, thus making them ideal for use in electronic materials. In other words, the hollow microparticles of this invention are preferably used in electronic materials.

[0139] The hollow microparticles of this invention contain the aforementioned fluorinated resin D and have an average particle size of 1.0 μm or more. Therefore, the dielectric constant can be reduced, and the surface area can be reduced when used in the same volume. Thus, it is a resin composition that can be used as a low-dielectric material. Since the specific surface area increases due to the small average particle size, the electrical properties are significantly reduced due to the influence of moisture and other substances adhering to the interface. Furthermore, the present invention provides a resin composition in which the hollow microparticles of the present invention are dispersed in an insulating resin. The insulating resin is not particularly limited, and examples include: fluorinated resins, epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, silicone resins, benzo[a]azole resins, melamine resins, urea resins, allyl resins, phenolic resins, unsaturated polyester resins, polyurethane resins, aniline resins, etc. Among these, fluorinated resins, epoxy resins, thermosetting resins, modified polyphenylene ether resins, thermosetting polyimide resins, silicone resins, benzo[a]azole resins, and melamine resins are preferred. These insulating resins can be used alone or in combination of two or more.

[0140] The content of hollow microparticles in the aforementioned low dielectric materials is not particularly limited and can be appropriately set according to the characteristics required for each application. For example, it can be 10 to 90 parts by mass per 100 parts by mass of insulating resin.

[0141] The applications of the hollow microparticles and the hardened components of this invention in electronic materials are not particularly limited, but examples include: interlayer insulating films for components of printed circuit boards, antenna substrates, or high-frequency connectors. They are particularly useful in high-frequency substrates used in 5G and 6G.

[0142] The hollow microparticles of this invention, being hollow, exhibit excellent low refractive index properties, thus enabling their application in various fields requiring low refractive indices. Specifically, the hollow microparticles of this invention are preferably used as low-refractive-index materials.

[0143] When used as a low-refractive-index material, it is particularly suitable for applications such as anti-reflective films, refractive index modifiers, fillers for optical adhesives, low-refractive-index lens materials, and prisms.

[0144] If the hollow microparticles of this invention are dispersed in a suitable adhesive to form a coating agent for an antireflective film, an antireflective film can be easily manufactured. Because the hollow microparticles of this invention have a low refractive index, excellent alkali resistance, and excellent dispersibility with adhesives, the resulting antireflective film can effectively suppress reflection from transparent substrates, is highly resistant to contamination and easy to clean, and also exhibits excellent mechanical strength. Furthermore, the antireflective coating agent containing the hollow microparticles and adhesive of the present invention, and the antireflective film made using the hollow microparticles of the present invention or the antireflective coating agent of the present invention are also part of the present invention.

[0145] The antireflective coating agent of the present invention contains the hollow microparticles and adhesive of the present invention. As for the aforementioned adhesive, there are no particular limitations as long as it is a transparent material that can form a film; both organic materials such as resins and inorganic materials can be used. Examples of such organic materials include: cellulose derivatives such as triacetylcellulose, diacetylcellulose, propionic cellulose, butyric cellulose, acetopropionic acid cellulose, and nitrocellulose; polyamides, polycarbonates, polyesters (especially polyethylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate), polyethylene 1,2-diphenoxyethane-4,4-dicarboxylate, polybutylene terephthalate, polyethylene naphthalate, etc.) as described in Japanese Patent Publication No. 48-40414, polystyrene, polypropylene, polyethylene, polymethylpentene, polyurethane, polyetherurethane, polyarylate, polyetherimide, polymethyl methacrylate, or various fluoropolymers thereof, and other relatively low refractive index transparent resins. Furthermore, when using a transparent resin as an adhesive, it is preferable to use one with a glass transition temperature lower than that of the hollow microparticles of this invention. In this way, the adhesive functions as a binder between the hollow microparticles during film formation, thereby achieving sufficient film strength.

[0146] Examples of such inorganic materials include: alkoxides of various elements, salts of organic acids, and coordination compounds bonded to coordination compounds. Specifically, examples include: titanium tetraethanol, titanium tetraisopropoxide, titanium tetran-propoxide, titanium tetran-butoxide, titanium tetra(secondary butanol)-titania, titanium tetra(tertiary butanol)-titania, aluminum triethanolamine, aluminum triisopropoxide, aluminum tributoxide, antimony triethanolamine, antimony tributoxide, zirconium tetraethanolamine, zirconium tetraisopropoxide, zirconium tetran-propoxide, zirconium tetran-propoxide, and so on. Metal alkoxides such as zirconium n-butoxide, tetra(secondary butol) zirconium, and tetra(tertiary butol) zirconium compounds; chelating compounds such as titanium diisopropoxide diacetone, titanium dibutoxide diacetone, titanium diethanolate diacetone, zirconium diacetone, aluminum acetone, aluminum di-n-butoxide monoethylacetate, aluminum diisopropoxide monoethylacetate, and zirconium tri-n-butoxide monoethylacetate; and active inorganic polymers with zirconium carbonate amine or zirconium as the main component.

[0147] The mixing ratio of hollow microparticles to the binder in this invention is not particularly limited, but the preferred lower limit for the mixing amount of hollow microparticles is 5% by volume, and the preferred upper limit is 95% by volume. If it is less than 5% by volume, the refractive index of the obtained antireflective film may not be sufficiently reduced; if it exceeds 95% by volume, the mechanical strength of the obtained antireflective film may deteriorate. A more preferred lower limit is 30% by volume, a more preferred upper limit is 90% by volume, and a more preferred lower limit is 50% by volume, and a more preferred upper limit is 80% by volume.

[0148] When a hardened type of coating agent is used as the adhesive in the antireflective film of the present invention, it may be an emulsion in which hollow microparticles are suspended. In other cases, it may be obtained by diluting it in a suitable volatile solvent. The diluents mentioned above are not particularly limited, but in terms of the stability, wettability, and volatility of the constituents, preferred solvents include, for example, alcohols such as methanol, ethanol, isopropanol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether; diols such as ethylene glycol, propylene glycol, and hexanediol; glycol ethers such as ethyl ceroxythreon, butyl ceroxythreon, ethyl carbitol, and butyl carbitol; aliphatic hydrocarbons such as hexane, heptane, and octane; halogenated hydrocarbons; aromatic hydrocarbons such as benzene, toluene, and xylene; and N-methylpyrrolidone and dimethylformamide. These diluents can be used alone or in combination of two or more.

[0149] The anti-reflective film of the present invention can be manufactured by the following method: coating the anti-reflective film of the present invention onto a release film or the like with a coating agent, or directly coating it onto a transparent substrate, and then drying it. There are no particular limitations on the method for applying the antireflective coating agent of the present invention. Examples include: dip coating, spin coating, curtain coating, spray coating, roller coating, gravure roller coating, air blade coating, grid coating, line blade coating, knife coating, reverse coating, transfer roller coating, micro-gravure coating, contact roller coating, cast coating, slot coating, calendering coating, and die coating.

[0150] The antireflective film of the present invention is obtained by coating an antireflective film of the present invention onto a release film or a transparent substrate with a coating agent, followed by drying to form a coating film, and then hardening the coating film by heating, humidifying, ultraviolet irradiation, electron beam irradiation, etc.

[0151] The antireflective film of the present invention preferably has a smooth surface. In this specification, "smooth surface" means that the surface roughness Rz calculated by the method specified in JIS B0601 is less than 0.2 μm. Because of its smooth surface, the anti-reflective film of the present invention will not turn white due to diffuse reflection of light on the surface. Furthermore, dirt such as fingerprints, sebum, sweat, and cosmetics are not easily attached to the surface, and temporarily attached dirt can be easily removed.

[0152] In addition to the layer formed using the antireflective coating agent of this invention, the antireflective film of this invention may also have a substrate layer. By having a substrate layer, the mechanical strength and operability of the antireflective film of this invention are improved. As for the aforementioned substrate layer, there are no particular limitations as long as it is transparent. In terms of formability or mechanical strength, it is preferably composed of a transparent resin that can be used as the aforementioned adhesive.

[0153] The thickness of the antireflective film of the present invention is not particularly limited, but the preferred lower limit is 0.05 μm and the preferred upper limit is 100 μm. If it is less than 0.05 μm, the scratch resistance will be insufficient, and if it exceeds 100 μm, the film will become easy to break. Furthermore, when the antireflective film of the present invention has the aforementioned substrate layer, the thickness of the substrate layer is not particularly limited, but the preferred lower limit is 50 μm and the preferred upper limit is 500 μm. If the thickness is less than 50 μm, the strength of the antireflective film of the present invention will deteriorate; if the thickness exceeds 500 μm, the transparency of the antireflective film of the present invention will deteriorate, and it will be difficult to see the internal visual information. [Example]

[0154] The present invention will then be illustrated by examples, but the present invention is not limited to these examples.

[0155] [Example 1] 2,2,2-trifluoroethyl methacrylate (3FM) was used as a fluorinated monomer, ethylene glycol dimethacrylate (EGDM) was used as a crosslinking monomer, a toluene solution (Sp value 18.2 (J / cm 3) 1 / 2) that dissolves polystyrene (PS) (degree of polymerization 2,000) (Sp value 18.4 (J / cm 3) 1 / 2) as a phase separation promoter was used as a solvent for the oil phase, 2,2-azobis(4-methoxy-2,4-dimethylpentanonitrile) (V-70) (a low-temperature initiator) was used as an initiator, and polyvinyl alcohol (PVA) with Pn=1700 and saponification degree=88% was used as a dispersion stabilizer. According to the composition in Table 1 below, EGDM as a crosslinking monomer and 3FM as a fluorinated monomer were added to a toluene solution that dissolves PS in a weight ratio of 1:1. Then, a homogenized oil phase that dissolves initiator V-70 was dispersed in an aqueous medium using a homogenizer to prepare suspension droplets. Polymerization was carried out under nitrogen atmosphere at 30°C and 400 rpm for 5 hours to produce hollow microparticles of fluorinated resin.

[0156] An optical microscope image of the suspended droplets before polymerization is shown in Figure 1(a), and an optical microscope image of the hollow microparticles after polymerization is shown in Figure 1(b). The optical microscope image before polymerization confirms a uniform suspended droplet. The optical microscope image after polymerization suggests the formation of hollow particles. After drying the obtained hollow microparticles, SEM samples were prepared. If the particles were intentionally broken, as shown in Figure 2, it clearly shows a hollow structure even in the dry state. Hereinafter, the sample obtained in Example 1 will be referred to as "3FM1:1".

[0157] [Comparative Example 1] Without adding PS and toluene, polymerization was carried out in the same manner as in Example 1, resulting in solid particles without a hollow structure. Hereinafter, the sample obtained in Comparative Example 1 will be referred to as "3FM solid".

[0158] [Example 2] The crosslinking monomer EGDM and the fluorinated monomer 3FM were changed to a mass ratio of 1:2 (0.22g:0.44g). Otherwise, polymerization was carried out in the same manner as in Example 1 to produce hollow microparticles containing fluorinated resin. An optical microscope image of the suspended droplet before polymerization is shown in Figure 3(a), and an optical microscope image of the hollow microparticles after polymerization is shown in Figure 3(b). Although a slight inhomogeneity of the inner wall of the hollow structure was observed, it was confirmed that hollow microparticles identical to those obtained in "3FM1:1" were obtained. Hereinafter, the obtained sample will be referred to as "3FM1:2". Furthermore, it can be confirmed that hollow microparticles with a diameter of over 10 μm form nested structures within the particles. This is believed to be a result of the polymer precipitating before reaching the outermost shell.

[0159] [Example 3] According to the compositional changes in Table 1 below, the types and amounts of each component were modified, except that polymerization was carried out in the same manner as in Example 1 to produce hollow microparticles containing fluorinated resin. In Table 1, 5FM represents 2,2,3,3,3-pentafluoropropyl methacrylate, represented by CH 2=C(CH 3)COOCH 2CF 2CF 3. The results of observation with an optical microscope confirmed that hollow microparticles were obtained, which were the same as those used in Examples 1 and 2.

[0160] [Comparative Example 2] As shown in Table 1 below, the types and amounts of each component were changed, and the polymerization speed was set to 400 rpm. Otherwise, polymerization was carried out in the same manner as in Example 1 to produce hollow microparticles containing fluorinated resin. In Table 1, 13FM is methacrylate-1H,1H,2H,2H-tetrafluorooctyl ester (13FM) represented by CH 2=C(CH 3)COOCH 2CH 2(CF 2) 5CF 3.

[0161] An optical microscope image of the suspended droplets before polymerization is shown in Figure 4(a), and an optical microscope image of the particles after polymerization is shown in Figure 4(b). As shown in Figure 4(b), it was confirmed that no hollow microparticles were obtained. Hereinafter, the obtained sample will be referred to as "13FM hollow".

[0162] [Example 4] As shown in Table 1 below, the types and amounts of each component are changed. Otherwise, polymerization is carried out in the same manner as in Example 1 to produce hollow microparticles containing fluorinated resin.

[0163] An optical microscope image of the suspended droplets before polymerization is shown in Figure 5(a), and an optical microscope image of the particles after polymerization is shown in Figure 5(b). The optical microscope image before polymerization shows uniform suspended droplets. Furthermore, the optical microscope image after polymerization indicates the presence of clear shell walls in a system containing 10% by mass PS, indicating the fabrication of hollow microparticles with fluorinated resin in the shell walls. The SEM images of the obtained particles are shown in Figure 6(a), the EDX mapping image of the shell wall is shown in Figure 6(b), and the SEM image of the broken particles is shown in Figure 6(c). The SEM images show that the prepared particles are true spherical and smooth. Elemental analysis of the shell wall using EDX mapping also confirmed the presence of fluorine in the shell wall. Furthermore, SEM observation of the broken particles confirmed that the particles are hollow inside. These results indicate that hollow microparticles with fluorinated resin shell walls can be produced in a system containing 10% PS by mass. This sample will be referred to as "13FM1:1". [Table 1] Example 1 Comparative Example 1 Example 2 Example 3 Comparative Example 2 Example 4 Abbreviation 3FM1:1 3FM1 3FM1:2 5FM1:1 13FM Zhongshi 13FM1:1 EGDM(g) 0.33 0.33 0.22 0.33 0.33 0.33 3FM(g) 0.33 0.33 0.44 5FM(g) 0.33 13FM 0.33 0.33 PS(g) 0.066 0.066 0.066 0.066 Toluene (g) 0.594 0.594 0.594 0.590 0.660 V-70(mg) 26.7 26.7 26.7 26.7 26.7 26.7 PVA (mg) 20 20 20 20 20 20 Water (g) 20 20 20 20 20 20

[0164] [Implementation Example 5] According to the composition in Table 2 below, suspension droplets were prepared by dispersing a homogeneous oil phase in an aqueous medium using a homogeneous base. This homogeneous oil phase was obtained by dissolving EGDM and 13FM in a toluene solution that dissolves PS at 25°C. The mixture was heated to 70°C under nitrogen atmosphere, and BPO was added to the suspension. Polymerization was then carried out at 70°C with stirring at 400 rpm for 5 hours to produce hollow microparticles of fluorinated resin. Furthermore, in Table 2, BPO is benzoyl peroxide, a mesophilic initiator.

[0165] [Table 2] Example 5 EGDM(g) 0.33 3FM(g) 5FM(g) 13FM 0.44 PS(g) 0.077 Toluene (g) 0.770 BPO (mg) 26.7 PVA (mg) 20 Water (g) 20

[0166] The optical microscope image before polymerization is shown in Figure 7(a), the optical microscope image after polymerization is shown in Figure 8(a), and the SEM image after polymerization is shown in Figure 8(b). As can be seen from Figure 8(a), a clear shell wall was formed. The SEM image of the broken particles shown in Figure 8(b) also confirmed that the particles are hollow inside. Hollow microparticles with a high fluorine content as the target material were successfully produced.

[0167] [evaluate] The physical properties of the microparticles obtained in the examples and comparative examples were evaluated. As sampling and pretreatment conditions, the synthesized emulsion solution was allowed to stand for a sufficient amount, and a suitable amount of the self-precipitated portion was carefully collected using a dropper. After air drying, it was dried in a blower dryer at 80°C for 24 hours. Elemental analysis and thermal analysis (TG / DTA, DSC) were performed on the sample.

[0168] [Fluorine content] A 10 mg sample was burned using an oxygen cylinder combustion method, and the decomposed gas was absorbed in 20 ml of deionized water. The concentration of fluoride ions in the absorption liquid was determined using a fluoride-selective electrode method (fluoride ion meter, Orion Corporation, model 901), and the concentration was calculated as a percentage (mass %). Elemental analysis of fluorine was performed, and the composition (mass%) of fluorine-containing monomers in the polymer was calculated from the analytical value (F mass%). Here, the amount of PS was uniformly calculated as 10% by mass of the crosslinking agent. The results are shown in Table 3.

[0169] [Table 3] Abbreviation Analysis values Composition (mass %) calculated from elemental analysis F quality% EGDMA 3FM 13FM PS Comparative Example 1 3FM Zhongshi 14.7 56.6 43.4 - - Example 1 3FM1:1 13.4 55.5 39.5 - 5 Example 2 3FM1:2 19.1 39.6 56.4 - 4 Comparative Example 2 13FM Zhongshi 27.4 52.0 - 48.0 - Example 4 13FM1:1 25.5 50.4 - 44.6 5

[0170] [Thermal decomposition temperature] Using a differential thermal calorimetry (DTC) thermogravimetric analyzer (Hitachi High-Tech Science Co., Ltd., STA7200), the temperature at which the mass loss of the sample reached 1% was measured under ambient air conditions at a heating rate of 10°C / min. The results are summarized in Table 4.

[0171] [Table 4] Abbreviation TGA / DTA 1% decomposition temperature Comparative Example 1 3FM Zhongshi 193.1 Example 1 3FM1:1 166.1 Example 2 3FM1:2 207.0 Comparative Example 2 13FM Zhongshi 147.3 Example 4 13FM1:1 199.4

[0172] [Glass Transfer Temperature] Using a DSC (Differential Scanning Calorimeter: Hitachi High-Tech Science Co., Ltd., DSC7000), the temperature range from 30°C to 200°C was heated at a rate of 10°C / minute (first run) - cooled down - heated up (second run). The midpoint of the endothermic curve during the second run was set as the glass transition temperature (°C). However, since all samples were fully cross-linked, as shown in Table 5, a clear glass transition temperature (Tg) or melting point (Tm) could not be observed.

[0173] [Table 5] Abbreviation DSC Tg (°C) Tm (°C) Comparative Example 1 3FM Zhongshi Unobservable Unobservable Example 1 3FM1:1 Unobservable Unobservable Example 2 3FM1:2 Unobservable Unobservable Comparative Example 2 13FM Zhongshi Unobservable Unobservable Example 4 13FM1:1 Unobservable Unobservable

[0174] [Particle size] The particle size analysis software LUZEX AP was used to analyze optical microscope images of hollow microparticles to calculate the average particle size, maximum particle size, minimum particle size, and CV value. Specifically, images of different locations were taken, and the average particle size, maximum particle size, minimum particle size, and CV value were calculated by ensuring that the total number of particles was 50 or higher. The results are shown in Table 6. [] [Table 6] Abbreviation Average particle size CV value Minimum particle size Maximum particle size μm μm μm Comparative Example 1 3FM Zhongshi 13.2 27.4% 8.3 19.1 Example 1 3FM1:1 8.0 29.1% 4.3 13.2 Example 2 3FM1:2 7.8 19.1% 4.0 9.9 Example 3 5FM1:1 10.2 25.8% 6.0 14.7 Comparative Example 2 13FM Zhongshi 10.1 33.9% 6.7 16.1 Example 4 13FM1:1 8.5 29.9% 4.3 15.6

[0175] [Membrane Formation 1] The obtained hollow microparticle dispersion 3FM1:2 was mixed in an appropriate amount with Daikin Industries' SE-405 fluoropolymer dispersion (50% solids concentration) and then ultrasonically cleaned for 15 minutes. Subsequently, a film was formed on a PET substrate using a doctor blade adjusted to 15 mils. After drying at room temperature, the film was dried in a 60°C blower dryer for 12 hours. Various measurements were performed on the obtained film. The thickness was measured using a micrometer, including the PET substrate, and the difference between the thickness and the monomer content of the PET substrate was taken as the film thickness. The film thickness was calculated as the average of five measurements. Furthermore, the content of 3FM1:2 was calculated from the results of fluorine elemental analysis. Furthermore, a membrane with 3FM solidity was also prepared in the same manner, using only SE-405 without the addition of microparticles. The results are shown in Table 7.

[0176] [Table 7] microparticles Microparticle addition amount Film thickness (μm) Membrane 1 Example 2 3FM1:2 5.60% of mass 125 Membrane 2 Example 2 3FM1:2 14.00% of mass 125 Membrane 3 Comparative Example 1 3FM Zhongshi 2.80% by weight 109 Membrane 4 - none 0.00% mass 100

[0177] [Sectional SEM Observation] The cross-sectional SEM images of the membrane prepared as described above (microparticles: 3FM1:2, microparticle addition amount: 14.0% by mass) are shown in Figures 9 and 10. The nested structure observed in the individual particle SEM was also observed in the cross-sectional SEM, and hollow structures were also confirmed. Nested structures were confirmed in large-diameter particles, and hollow structures were confirmed in small-diameter particles.

[0178] [Dielectric constant and dielectric loss tangent] Aluminum was deposited onto both sides of the film prepared above in a vacuum to prepare a sample. The capacitance and dielectric loss tangent of the sample at 25°C and 1 kHz were measured using an LCR meter. The relative permittivity was calculated from the obtained capacitances and set as the permittivity. The results are shown in Table 8 below.

[0179] [Table 8] microparticles Microparticle addition amount Film thickness (μm) Relative permittivity Dielectric loss tangent Membrane 1 Example 2 3FM1:2 5.60% of mass 125 7.53±0.25 0.190 Membrane 2 Example 2 3FM1:2 14.00% of mass 125 7.41±0.50 0.172 Membrane 3 Comparative Example 1 3FM Zhongshi 2.80% by weight 109 8.65±0.72 0.216 Membrane 4 - none 0.00% mass 100 8.50±0.42 0.221

[0180] The results of dielectric loss tangent (tanδ) are summarized in the figure and illustrated in Figure 11. If, according to the composite law, we assume that the tanδ of this system is a linear approximation, then as shown in the figure, the result of mixing solid microparticles is almost on the theoretical curve, but the result of hollow microparticles deviates significantly downward, which is considered to be the effect of air (hollow).

[0181] [Membrane Formation 2] Using 13FM1:1 as hollow microparticles, the films shown in Tables 9 and 10 below were fabricated in the same manner as film fabrication 1 described above. The film thickness, relative permittivity, and dielectric loss tangent were measured. Compared to the film fabricated solely from SE405 without using hollow microparticles, the relative permittivity and dielectric loss tangent of each film were reduced.

[0182] [Table 9] membrane thickness 13FM1:1 Content Relative permittivity μm wt% 1 kHz 10 kHz 20 kHz 100 kHz Membrane 5 34.7 19.2 5.84 5.16 5.04 4.73 Membrane 6 35.9 9.6 6.13 5.29 5.15 4.79 Membrane 4 100 0 8.05 6.17 5.88 5.26

[0183] [Table 10] membrane thickness 13FM1:1 Content tanδ μm wt% 1 kHz 10 kHz 20 kHz 100 kHz Membrane 5 34.7 19.2 0.117 0.076 0.071 0.066 Membrane 6 35.9 9.6 0.142 0.088 0.081 0.074 membrane 4 100 0 0.221 0.141 0.126 0.102

[0184] None

Claims

1. A method for manufacturing hollow microparticles, comprising: a dispersion step, wherein a solution containing a fluorinated monomer, a phase separation promoter, and a non-polymerizable solvent is dispersed in water to obtain a dispersion; and a polymerization step, wherein the fluorinated monomer is polymerized to obtain hollow microparticles containing a fluorinated resin; wherein the average particle size of the hollow microparticles is 1.0 μm or more, and the fluorinated monomer is a monomer represented by the following general formula (B1): CX1X2=CY1Z (B1) (where X1, X2, and Y1 are independently H, CH3, F, or Cl, Z is F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1-Y) 1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is a group represented by F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms), or a group represented by the following formula: (where X6 to X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1 to 8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein, Each of X1, X2, Y1, and Z contains one or more F.

2. The method for manufacturing hollow microparticles as described in claim 1, wherein, The fluorinated monomer mentioned above is a fluorinated acrylic monomer (C1) represented by the following general formula (C1): CH2=CX3-COORf 2 (C1) (where X3 is H, CH3, F, Cl or CF3, and Rf 2 is a fluorinated alkyl group with 1 to 20 carbon atoms that can contain ether bonds between carbon atoms).

3. A method for manufacturing hollow microparticles as described in claim 1, wherein, The phase separation promoter described above is dissolved in the non-polymerizable solvent at room temperature. When the Sp value of the phase separation promoter is set to SA (J / cm3)1 / 2 and the Sp value of the non-polymerizable solvent is set to SB (J / cm3)1 / 2, the following relationship is satisfied: |SA-SB| < 3 (J / cm3)1 / 2.

4. A method for manufacturing hollow microparticles as described in claim 1, wherein, The aforementioned phase separation promoter is a polymer comprising a polymerization unit based on a monomer represented by the following general formula: CH2=CX4Y2 (where X4 is H, CH3, F, Cl, or CF3, and Y2 is Cl, C6H4R1, C6H3R2R3, COOR4, or OCOR5 (here, R1, R2, R3, R4, and R5 are independently H, OH, or alkyl groups with 1 to 40 carbon atoms that can be substituted by halogen atoms)).

5. A method for manufacturing hollow microparticles as described in claim 1, wherein, The aforementioned phase separation promoter is selected from at least one of the groups consisting of aromatic vinyl polymers and poly(meth)acrylate alkyl esters.

6. A method for manufacturing hollow microparticles as described in claim 1, wherein, The fluorine content of the above-mentioned fluorine-containing monomers is 30% by mass or more.

7. A method for manufacturing hollow microparticles as described in claim 1, wherein, The solution described above further contains cross-linking monomers.

8. A method for manufacturing hollow microparticles as described in claim 1, wherein, The aforementioned non-polymerizable solvents are aromatic hydrocarbons, esters, or saturated hydrocarbons having 8 to 18 carbon atoms, or halogenated derivatives thereof.

9. A method for manufacturing hollow microparticles as described in claim 1, wherein, The above dispersion step is either a step of dispersing the above solution in water at a temperature of 50°C or higher to obtain a dispersion, or a step of dispersing the above solution in water at a temperature of less than 50°C to obtain a dispersion, and then heating the obtained dispersion to a temperature of 50°C or higher.

10. The method for manufacturing hollow microparticles as claimed in claim 1, further comprising, after the dispersion step and before the polymerization step, adding an oil-soluble initiator to the dispersion.

11. A method for manufacturing hollow microparticles as claimed in claim 1, comprising: a removal step of removing the non-polymerizable solvent from the hollow microparticles obtained from the polymerization step described above.

12. A hollow microparticle containing a fluorinated resin D comprising a polymerization unit based on a fluorinated monomer and a phase separation promoter, and having an average particle size of 1.0 μm or more, wherein the fluorinated monomer is a monomer (B2) represented by the following general formula (B2): CX1X2=CY1Z (B2) (where X1, X2, and Y1 are independently the same or different, being H, CH3, F, or Cl, Z is a group represented by F, -Q-Rf1-Y (Q is a single bond, -O-, -O-(C=O)-, or -C(=O)-O-, Rf1 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms, and Y is a group represented by F, H, -OH, -COOH, -COOR (R is an alkyl group with 1 to 20 carbon atoms)), or a group represented by the following formula: (In the formula, X6 to X10 are independently hydrogen atoms, fluorine atoms, or hydrocarbon groups with 1 to 8 carbon atoms that can be substituted by fluorine or chlorine), or -SO3H, wherein, Each of X1, X2, Y1, and Z contains one or more F.

13. As in request item 12, hollow microparticles, wherein, The fluorinated monomer mentioned above is a fluorinated acrylic acid monomer (C2) represented by the following general formula (C2): CH2=CX3-COORf 2 (C2) (where X3 is H, CH3, F, Cl or CF3, and Rf 2 is a fluorinated alkyl group with 1 to 20 carbon atoms that may contain ether bonds between carbon atoms).

14. As in request item 12, hollow microparticles, wherein, The aforementioned phase separation promoter is a polymer comprising a polymerization unit based on a monomer represented by the following general formula: CH2=CX4Y2 (where X4 is H, CH3, F, Cl, or CF3, and Y2 is Cl, C6H4R1, C6H3R2R3, COOR4, or OCOR5 (here, R1, R2, R3, R4, and R5 are independently H, OH, or alkyl groups with 1 to 40 carbon atoms that can be substituted by halogen atoms)).

15. As in request item 12, hollow microparticles, wherein, The aforementioned phase separation promoter is selected from at least one of the groups consisting of aromatic vinyl polymers and poly(meth)acrylate alkyl esters.

16. As in request item 12, hollow microparticles, wherein, The aforementioned fluorinated resin D further comprises polymerization units based on crosslinking monomers.

17. As in request item 12, hollow microparticles, wherein, The fluorine content of the aforementioned fluorinated resin D is 15% by mass or more.

18. The hollow microparticles of claim 12 are composed of a shell containing the aforementioned fluorinated resin D and a hollow portion, and have a monoporous structure.

19. A hardening composition comprising hollow microparticles of any one of claims 12 to 18.

20. A coating composition comprising hollow microparticles of any one of claims 12 to 18.

21. Hollow microparticles, as in request item 12, for use in electronic materials.

Images