Fluoropolymer-containing composition, method for producing fluoropolymer, and lens for ultraviolet light-emitting element containing fluoropolymer

Abstract

The purpose of the present invention is to provide: a composition containing a fluorine-containing polymer having high ultraviolet light transmittance; a method for producing a fluorine-containing polymer having high ultraviolet light transmittance; a lens for an ultraviolet light-emitting element, which contains a fluorine-containing polymer having high ultraviolet light transmittance; and the like. The composition contains a fluorine-containing polymer (A) and at least one compound (BC) selected from the group consisting of a polymerization initiator (B) and a decomposition product (C) of the polymerization initiator (B), the content of the compound (BC) is 0.1-100 ppm by mass relative to the mass of the composition, and the fluorine-containing polymer (A) contains a structural unit represented by formula (A) as a main component. In the formula, each of R1-R4 independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group.

Description

TECHNICAL FIELD

[0001] The present application relates to a composition containing a fluorine-containing polymer, a method for producing a fluorine-containing polymer, and a lens for an ultraviolet light emitting element containing a fluorine-containing polymer. BACKGROUND

[0002] A fluorine-containing polymer containing an oxolane ring is known to have high transparency, and its use in the optical field is being studied. On the other hand, in recent years, the use of ultraviolet light emitting elements has been expanding, and a polymer having high ultraviolet transmittance is sought.

[0003] Patent Documents 1 and 2 disclose that by making the terminal portion of a fluorine-containing polymer not contain a carbonyl group, yellowing of the fluorine-containing polymer can be suppressed, and the ultraviolet transmittance is improved.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-155736

[0007] Patent Document 2: International Publication No. 2014 / 156996 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, the inventors of the present application have noted that a fluorine-containing polymer containing an oxolane ring sometimes has reduced ultraviolet transmittance even if the polymer is one whose terminal portion does not contain a carbonyl group. The object of the present application is to provide a composition containing a fluorine-containing polymer having high ultraviolet transmittance, a method for producing a fluorine-containing polymer having high ultraviolet transmittance, a lens for an ultraviolet light emitting element containing a fluorine-containing polymer having high ultraviolet transmittance, and the like.

[0010] MEANS OF SOLVING THE PROBLEMS

[0011] The inventors of the present application have learned that a polymerization initiator used to produce a fluorine-containing polymer and / or a decomposition product thereof are mixed into the produced fluorine-containing polymer, absorb ultraviolet light, and can cause the ultraviolet transmittance of the fluorine-containing polymer to decrease.

[0012] It was thus found that when a fluorine-containing polymer is produced by precipitation polymerization, that is, when a raw material monomer is polymerized in a solvent, and the produced fluorine-containing polymer is precipitated in the solvent, if the solute (monomer, polymerization initiator, and decomposition product of the polymerization initiator) and the solvent have a solubility index R within a certain range, a fluorine-containing polymer in which the amount of a polymerization initiator and / or a decomposition product thereof mixed into the fluorine-containing polymer is reduced can be produced.

[0013] The present application typically includes the following modes.

[0014] Item 1. A composition containing a fluorine-containing polymer (A) and a compound (BC) which is at least one selected from the group consisting of a polymerization initiator (B) and a decomposition product (C) of the polymerization initiator (B),

[0015] 0.1 to 100 mass ppm of the compound (BC) relative to the mass of the composition,

[0016] The fluorine-containing polymer (A) contains a structural unit represented by formula (A) as a main component.

[0017]

[0018] [In the formula, R 1 ~ R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group.]

[0019] Item 2. The composition according to Item 1, wherein the polymerization initiator (B) is a peroxide.

[0020] Item 3. The composition according to Item 1, wherein

[0021] The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3).

[0022]

[0023] [In the formula, R 11 , R 12 , R 13 and R 14 each independently represents a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other, and 4 to 20 carbon atoms can form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom,

[0024] R 13 and R 14 may be linked to each other, and 4 to 20 carbon atoms can form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom.]

[0025]

[0026] (In the formula, R 15 and R 16 each independently represent a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom.]

[0027]

[0028] (In the formula, R 17 and R 18 each independently represent a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom.]

[0029] Item 4. The composition according to any one of items 1 to 3, wherein the decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3).

[0030] The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3).

[0031]

[0032] (In the formula, R 41 and R 42 each independently represent a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group,

[0033] The alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other, and form a 4- to 20-membered ring having at least one fluorine atom with 4 to 20 carbon atoms as ring-forming atoms, or a 4- to 22-membered ring having at least one fluorine atom with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-forming atoms,

[0034] R 43 represents a fluorine atom or a hydroxyl group.]

[0035]

[0036] (In the formula, R 45represents a linear or branched alkyl group having 1 to 20 carbon atoms, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 4 to 8 carbon atoms, a cyclic fluoroalkyl group having 4 to 8 carbon atoms, or an aromatic group having 4 to 14 carbon atoms which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group.

[0037]

[0038] [In the formula, R 47 represents a linear or branched alkyl group having 1 to 20 carbon atoms, a linear or branched fluoroalkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 4 to 8 carbon atoms, a cyclic fluoroalkyl group having 4 to 8 carbon atoms, or an aromatic group having 4 to 14 carbon atoms which can have a fluorine atom, the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom,

[0039] R 49 represents a fluorine atom or a hydroxyl group.

[0040] Item 5. The composition according to any one of items 1 to 4, wherein the average transmittance at a wavelength of 240 nm to 340 nm is 85% or more.

[0041] Item 6. The composition according to any one of items 1 to 5, wherein the structural unit represented by the formula (A) is a structural unit represented by the formula (Al).

[0042]

[0043] Item 7. The composition according to any one of items 1, 4 to 6, wherein

[0044] The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by the formula (Bl), a compound represented by the formula (B2), and a compound represented by the formula (B3).

[0045]

[0046] [In the formula, R 11 and R 13 is a fluorine atom,

[0047] R 12 and R 14 each independently represents:

[0048] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0049] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0050] -O-(CF2)n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0051] — O— (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).

[0052]

[0053] [In the formula, R 15 and R 16 each independently represent a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.]

[0054]

[0055] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group or a phenyl group, and R 18 represents a t-butyl group, a t-hexyl group or a trifluoromethyl group.]

[0056] Item 8. The composition according to any one of Items 1 to 3 and 5 to 7, wherein

[0057] The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by Formula (C1), a compound represented by Formula (C2) and a compound represented by Formula (C3).

[0058]

[0059] [In the formula, R 41 represents a fluorine atom,

[0060] R 42 represents:

[0061] — (CF2) n1 CF3(wherein n1 represents an integer of 0 to 5),

[0062] — (CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0063] — O— (CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0064] — O— (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0065] R 43 represents a fluorine atom or a hydroxyl group.]

[0066]

[0067] [In the formula, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.]

[0068]

[0069] [In the formula, R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.]

[0070] Item 9. The composition according to item 1 or 5, wherein

[0071] the structural unit represented by the above formula (A) is a structural unit represented by formula (Al),

[0072]

[0073] the above polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2), and a compound represented by formula (B3),

[0074]

[0075] [In the formula, R 11 and R 13 are fluorine atoms,

[0076] R 12 and R 14 each independently represent:

[0077] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0078] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0079] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0080] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).]

[0081]

[0082] [In the formula, R 15 and R 16each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.

[0083]

[0084] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.]

[0085] The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3).

[0086]

[0087] [In the formula, R 41 represents a fluorine atom,

[0088] R 42 represents:

[0089] -(CF2) n1 CF3(wherein n1 represents an integer of 0 to 5),

[0090] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0091] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0092] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0093] R 43 represents a fluorine atom or a hydroxyl group.]

[0094]

[0095] [In the formula, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.]

[0096]

[0097] [In the formula, R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.]

[0098] Item 10. A method for producing a fluorine-containing polymer (A) having a polymerization step of polymerizing a fluorine-containing monomer (M) in the presence of the fluorine-containing monomer (M) represented by Formula (M), a polymerization initiator (B), and a solvent (D) to produce the fluorine-containing polymer (A) in the form of a precipitate,

[0099]

[0100] [In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group.]

[0101] The fluorine-containing polymer (A) contains a structural unit represented by Formula (A) as a main component,

[0102]

[0103] [In the formula, R 1 ~R 4 are the same as above.]

[0104] The value (R A ) of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the fluorine-containing polymer (A) is 4 or greater,

[0105] The value (R B ) of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the decomposition product (C) of the polymerization initiator (B) is 9 or less when the mass ratio of fluorine atoms in the decomposition product (C) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or greater,

[0106] The value (R C ) of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the decomposition product (C) of the polymerization initiator (B) is 9 or less when the mass ratio of fluorine atoms in the decomposition product (C) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or greater,

[0107] The solubility index R is calculated by the following formula.

[0108] R = {4 x (δD1 - δD2) 2 + (δP1 - δP2) 2 + (δH1 - δH2) 2} 0.5

[0109] [In the formula, δD1, δP1 and δH1 represent the dispersion term, the polarity term and the hydrogen bonding term, respectively, in the Hansen solubility parameters of element 1, and δD2, δP2 and δH2 represent the dispersion term, the polarity term and the hydrogen bonding term, respectively, in the Hansen solubility parameters of element 2.]

[0110] Item 11. The method for producing the fluorine-containing polymer (A) according to item 10, further comprising a filtration step of filtering the precipitate and the polymerization product liquid produced in the polymerization step, thereby removing the polymerization product liquid to obtain the fluorine-containing polymer (A).

[0111] Item 12. The method for producing the fluorine-containing polymer (A) according to item 10 or 11, wherein the polymerization initiator (B) is a peroxide.

[0112] Item 13. The method for producing the fluorine-containing polymer (A) according to item 10 or 11, wherein the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3).

[0113]

[0114] [In the formula, R 11 , R 12 , R 13 and R 14 independently represent a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other, and 4 to 20 carbon atoms can form a 4 to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4 to 22-membered ring having at least one fluorine atom as a ring-constituting atom,

[0115] R 13 and R 14 may be linked to each other, and 4 to 20 carbon atoms can form a 4 to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4 to 22-membered ring having at least one fluorine atom as a ring-constituting atom.

[0116]

[0117] [In the formula, R 15 and R 16each independently represents a linear or branched C1-C20 alkyl group, a linear or branched C1-C20 fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0118]

[0119] [In the formula, R 17 and R 18 each independently represents a linear or branched C1-C20 alkyl group, a linear or branched C1-C20 fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0120] Item 14. The method for producing the fluorine-containing polymer (A) according to any one of Items 10 to 13, wherein the decomposition product (C) of the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by Formula (C1), a compound represented by Formula (C2), and a compound represented by Formula (C3).

[0121]

[0122] [In the formula, R 41 and R 42 each independently represents a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group,

[0123] the above alkyl and fluoroalkyl groups can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other, 4 to 20 carbon atoms are taken as ring-forming atoms to form a 4- to 20-membered ring having at least one fluorine atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom are taken as ring-forming atoms to form a 4- to 22-membered ring having at least one fluorine atom,

[0124] R 43 represents a fluorine atom or a hydroxyl group.]

[0125]

[0126] [In the formula, R 45 represents a linear or branched C1-C20 alkyl group, a linear or branched C1-C20 fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group.]

[0127]

[0128] [In the formula, R 47 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom,

[0129] R 49 represents a fluorine atom or a hydroxyl group.]

[0130] Item 15. The method for producing the fluorine-containing polymer (A) according to any one of Items 10 to 14, wherein the fluorine-containing monomer (M) is a compound represented by Formula (M1),

[0131]

[0132] the structural unit represented by Formula (A) is a structural unit represented by Formula (A1).

[0133]

[0134] Item 16. The method for producing the fluorine-containing polymer (A) according to any one of Items 10 to 15, wherein the fluorine-containing monomer (M) contains 0.0001 to 10 mass% of a compound (N) with respect to the mass of the raw material monomers,

[0135] the compound (N) is a compound represented by Formula (N).

[0136]

[0137] [In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group, R 71 and R 72 each independently represents a hydrogen atom or a fluorine atom, in the case where either one of R 71 and R 72 is a hydrogen atom, the group of the other represents a fluorine atom.]

[0138] Item 17. The method for producing the fluorine-containing polymer (A) according to Item 16, wherein the compound (N) is at least one compound selected from a compound represented by Formula (N1) and a compound represented by Formula (N2).

[0139]

[0140]

[0141] Item 18. The method for producing a fluorine-containing polymer (A) according to any one of items 10, 11 and 14 to 17, wherein the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3).

[0142]

[0143] [In the formula, R 11 and R 13 are each independently a fluorine atom,

[0144] R 12 and R 14 each independently represent:

[0145] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0146] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0147] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0148] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).

[0149]

[0150] [In the formula, R 15 and R 16 each independently represent a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.]

[0151]

[0152] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group or a phenyl group, and R 18 represents a t-butyl group, a t-hexyl group or a trifluoromethyl group.]

[0153] Item 19. The method for producing a fluorine-containing polymer (A) according to any one of items 10 to 13 and 15 to 18, wherein the decomposed product (C) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2) and a compound represented by formula (C3).

[0154]

[0155] [In the formula, R41 represents a fluorine atom,

[0156] R 42 represents a fluorine atom or a hydroxyl group.

[0157] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0158] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0159] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0160] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0161] R 43 represents a fluorine atom or a hydroxyl group.

[0162]

[0163] (wherein, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.

[0164]

[0165] (wherein, R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

[0166] Item 20. The method for producing the fluorine-containing polymer (A) according to any one of Items 10 to 19, wherein the solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluorine-containing alcohol.

[0167] Item 21. The method for producing the fluorine-containing polymer (A) according to Item 10 or 11, wherein,

[0168] the fluorine-containing monomer (M) is a compound represented by formula (Ml),

[0169]

[0170] the fluorine-containing monomer (M) contains 0.0001 to 10 mass% of the compound (N) relative to the mass of the raw material monomer,

[0171] The above compound (N) is at least one compound selected from the group consisting of a compound represented by formula (N1) and a compound represented by formula (N2),

[0172]

[0173]

[0174] The above structural unit represented by formula (A) is a structural unit represented by formula (Al),

[0175]

[0176] The above polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2), and a compound represented by formula (B3),

[0177]

[0178] [In the formula, R 11 and R 13 are a fluorine atom,

[0179] R 12 and R 14 each independently represent:

[0180] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0181] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0182] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0183] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).

[0184]

[0185] [In the formula, R 15 and R 16 each independently represent a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.]

[0186]

[0187] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, and R 18represents a tertiary butyl group, a tertiary hexyl group or a trifluoromethyl group.

[0188] The above decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2) and a compound represented by formula (C3),

[0189]

[0190] [In the formula, R 41 represents a fluorine atom,

[0191] R 42 represents:

[0192] — (CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0193] — (CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0194] — O — (CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0195] — O — (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0196] R 43 represents a fluorine atom or a hydroxyl group.

[0197]

[0198] [In the formula, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.

[0199]

[0200] [In the formula, R 47 represents a methyl group, a tertiary butyl group, a tertiary nonyl group, a trifluoromethyl group, a perfluoroisopentyl group or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

[0201] The above solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

[0202] Item 22. A lens for an ultraviolet light emitting element containing a fluorochemical polymer (A), wherein,

[0203] The above fluorochemical polymer (A) contains a structural unit represented by formula (A) as a main component,

[0204]

[0205] (In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group.

[0206] The average transmittance of the fluorine-containing polymer (A) at a wavelength of 240 nm to 340 nm is 85% or more.

[0207] Item 23. The lens for an ultraviolet light emitting element according to item 22, wherein the structural unit represented by the formula (A) is a structural unit represented by the formula (Al).

[0208]

[0209] Item 24. A composition containing a fluorine-containing polymer (Al), wherein,

[0210] The fluorine-containing polymer (Al) is generated in the form of a precipitate by polymerizing a fluorine-containing monomer (Ml) in the presence of the fluorine-containing monomer (Ml), a polymerization initiator (B) and a solvent (D),

[0211]

[0212] The fluorine-containing polymer (Al) contains a structural unit represented by the formula (Al) as a main component,

[0213]

[0214] The fluorine-containing monomer (Ml) contains 0.0001 to 10 mass% of at least one compound selected from a compound represented by the formula (Nl) and a compound represented by the formula (N2) with respect to the mass of the raw material monomer,

[0215]

[0216]

[0217] The value (R (D) ) of the solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the fluorine-containing polymer (Al) is 4 or more, and the value (R (B) ) of the solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the polymerization initiator (B) is 9 or less when the mass ratio of fluorine atoms in the polymerization initiator (B) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or more, A1 B

[0218] ​​The value of the solubility index R calculated based on the Hansen solubility parameter of the above solvent (D) and the Hansen solubility parameter of the decomposition product (C) of the above polymerization initiator (B) (R C ) is 9 or less when the mass ratio of fluorine atoms in the above decomposition product (C) is less than 50 mass%, and is 6 or less when the above mass ratio is 50 mass% or more,

[0219] The above solubility index R is calculated by the following formula.

[0220] R = {4 x (δD1 - δD2) 2 + (δP1 - δP2) 2 + (δH1 - δH2) 2} 0.5

[0221] [In the formula, δD1, δP1, and δH1 represent the dispersion term, the polarity term, and the hydrogen bond term, respectively, in the Hansen solubility parameter of Element 1, and δD2, δP2, and δH2 represent the dispersion term, the polarity term, and the hydrogen bond term, respectively, in the Hansen solubility parameter of Element 2.]

[0222] Item 25. The composition containing the fluorine-containing polymer (Al) according to Item 24, wherein the above polymerization initiator (B) is a peroxide.

[0223] Item 26. The composition containing the fluorine-containing polymer (Al) according to Item 24, wherein the above polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by Formula (Bl), a compound represented by Formula (B2), and a compound represented by Formula (B3).

[0224]

[0225] [In the formula, R 11 , R 12 , R 13 , and R 14 independently represent a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group, and the above alkyl group and fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other, and 4 to 20 carbon atoms can form a 4- to 20-membered ring having at least one fluorine atom as a ring-forming atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4- to 22-membered ring having at least one fluorine atom as a ring-forming atom,

[0226] R 13 and R 14may be linked to each other, 4 to 20 carbon atoms as ring-forming atoms to form a 4 to 20-membered ring having at least one fluorine atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-forming atoms to form a 4 to 22-membered ring having at least one fluorine atom.

[0227]

[0228] [In the formula, R 15 and R 16 each independently represent a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom.]

[0229]

[0230] [In the formula, R 17 and R 18 each independently represent a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom.]

[0231] Item 27. The composition containing the fluorine-containing polymer (Al) according to Item 24 or 25, wherein the decomposition product (C) of the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by Formula (Cl), a compound represented by Formula (C2), and a compound represented by Formula (C3).

[0232]

[0233] [In the formula, R 41 and R 42 each independently represent a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group,

[0234] the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other, 4 to 20 carbon atoms as ring-forming atoms to form a 4 to 20-membered ring having at least one fluorine atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-forming atoms to form a 4 to 22-membered ring having at least one fluorine atom,

[0235] R 43 represents a fluorine atom or a hydroxyl group.]

[0236]

[0237] [In the formula, R 45 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group.]

[0238]

[0239] [In the formula, R 47 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom,

[0240] R 49 represents a fluorine atom or a hydroxyl group.]

[0241] Item 28. The composition containing the fluorine-containing polymer (Al) according to Item 24, wherein the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by Formula (Bl), a compound represented by Formula (B2), and a compound represented by Formula (B3).

[0242]

[0243] [In the formula, R 11 and R 13 are fluorine atoms,

[0244] R 12 and R 14 each independently represent:

[0245] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0246] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0247] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0248] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).]

[0249]

[0250] [In the formula, R15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.

[0251]

[0252] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

[0253] Item 29. The composition containing the fluorine-containing polymer (Al) according to any one of Items 24 to 26 and 28, wherein the decomposition product (C) is at least one compound selected from the group consisting of a compound represented by Formula (Cl), a compound represented by Formula (C2), and a compound represented by Formula (C3).

[0254]

[0255] [In the formula, R 41 represents a fluorine atom,

[0256] R 42 represents:

[0257] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0258] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0259] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0260] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0261] R 43 represents a fluorine atom or a hydroxyl group.

[0262]

[0263] [In the formula, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.

[0264]

[0265] [In the formula, R 47represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

[0266] Item 30. The composition containing the fluorine-containing polymer (Al) according to any one of Items 24 to 29, wherein the above-mentioned solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluorine-containing alcohol.

[0267] Item 31. The composition containing the fluorine-containing polymer (Al) according to Item 24, wherein,

[0268] the above-mentioned polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2), and a compound represented by formula (B3),

[0269]

[0270] [In the formula, R 11 and R 13 each independently represent a fluorine atom,

[0271] R 12 and R 14 each independently represent:

[0272] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0273] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0274] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0275] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5).

[0276]

[0277] [In the formula, R 15 and R 16 each independently represent a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.

[0278]

[0279] [In the formula, R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

[0280] The above decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2), and a compound represented by formula (C3),

[0281]

[0282] [In the formula, R 41 represents a fluorine atom,

[0283] R 42 represents:

[0284] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0285] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0286] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0287] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0288] R 43 represents a fluorine atom or a hydroxyl group.]

[0289]

[0290] [In the formula, R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group.]

[0291]

[0292] [In the formula, R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.]

[0293] The above solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

[0294] Effects of the Invention

[0295] The present application can provide a composition containing a fluorine-containing polymer having high ultraviolet transmittance, a method for producing a fluorine-containing polymer having high ultraviolet transmittance, a lens for an ultraviolet light emitting element containing a fluorine-containing polymer having high ultraviolet transmittance, and the like.

[0296] The production method of the present application can produce a fluoropolymer having high ultraviolet transmittance using a polymerization step and a filtration step without a removal step of a polymerization initiator and / or a decomposition product thereof after polymerization. DETAILED DESCRIPTION

[0297] The foregoing description of the present application is not intended to represent the various embodiments or all implementations of the present application.

[0298] The following description of the present application provides a more specific illustration of the embodiments of the examples.

[0299] In some parts of the present application, guidance is provided by way of illustration, and this illustration can be used in various combinations.

[0300] In various cases, the groups illustrated all function as non-exclusive and representative groups.

[0301] All publications, patents, and patent applications cited in this specification can be used to enable the disclosure herein.

[0302] Terminology

[0303] Unless specifically defined otherwise, the symbols and terms used in the present specification and claims can be construed as commonly used in the technical field of the present application.

[0304] In the present specification, the use of the expression "comprising" is intended to include the expressions "consisting essentially of and "consisting of."

[0305] Unless specifically defined otherwise, the procedures, treatments, or operations described in the present specification can be performed at room temperature.

[0306] In the present specification, room temperature can refer to a temperature in the range of 10 to 40°C.

[0307] In the present specification, the expression "Cn-Cm" (where n and m are each a number) means the number of carbon atoms is n or more and m or less, as generally understood by those skilled in the art.

[0308] In the present specification, unless otherwise specified, "alkyl" is a straight chain, branched, or cyclic alkyl group. As the alkyl group, for example, C1-C20 straight chain or branched alkyl groups (e.g., C1-C10, preferably C1-C7, more preferably C1-C6, still more preferably C1-C4, particularly preferably C1-C3 alkyl groups) such as methyl, ethyl, propyl (e.g., n-propyl, isopropyl), butyl (e.g., n-butyl, isobutyl, sec-butyl, t-butyl), pentyl (e.g., n-pentyl, t-pentyl, neopentyl, isopentyl, sec-pentyl, 3-pentyl), hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, and the like; C3-C10 cyclic alkyl groups (e.g., C3-C6, C4-C6, C3-C5, C5-C6, C4-C8 alkyl groups) such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, and the like are exemplified.

[0309] In the present specification, unless otherwise specified, "alkoxy" is a straight chain, branched, or cyclic alkoxy group. The alkoxy group can be a group represented by RO- [in the formula, R is an alkyl group (e.g., C1-C20 alkyl group, C1-C10 alkyl group, C1-C7 alkyl group, C1-C6 alkyl group, C1-C4 alkyl group, C1-C3 alkyl group)].

[0310] Examples of the alkoxy group include straight chain or branched alkoxy groups such as methoxy, ethoxy, propoxy (e.g., n-propoxy, isopropoxy), butoxy (e.g., n-butoxy, isobutoxy, sec-butoxy, t-butoxy), pentoxy (e.g., n-pentoxy, t-pentoxy, neopentoxy, isopentoxy, sec-pentoxy, 3-pentoxy), hexyloxy, heptyloxy, octyloxy, nonyloxy, decoxy, undecoxy, dodecoxy, tridecoxy, tetradecoxy, pentadecoxy, hexadecoxy, heptadecoxy, octadecoxy, nonadecoxy, eicocoxy, and the like (e.g., C1-C20 alkoxy group (e.g., C1-C10, preferably C1-C7, more preferably C1-C6, still more preferably C1-C4, particularly preferably C1-C3 alkoxy group)); cyclic C3-C10 alkoxy groups (e.g., C3-C6, C4-C6, C3-C5, C5-C6, C4-C8 alkoxy groups) such as cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexoxy, cycloheptoxy, cyclooctoxy, adamantyloxy, and the like.

[0311] In the present specification, unless otherwise specified, "fluoroalkyl" is a straight chain, branched, or cyclic alkyl group in which at least one hydrogen atom is replaced with a fluorine atom. The fluoroalkyl group also includes a perfluoroalkyl group in which all the hydrogen atoms of the alkyl group are replaced with fluorine atoms.

[0312] The number of carbon atoms of the fluoroalkyl group may be, for example, 1 to 20, 1 to 10, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, or 1.

[0313] Examples of the fluoroalkyl group include linear or branched C1-C20 fluoroalkyl groups (e.g., C1-C10, C1-C4, C1-C3, etc., preferably C1-C7, more preferably C1-C6 fluoroalkyl groups (preferably perfluoroalkyl groups); cyclic C3-C10 fluoroalkyl groups (e.g., C3-C6, C4-C6, C3-C5, C5-C6, C4-C8 fluoroalkyl groups) (preferably perfluoroalkyl groups) having 1 to 3 fluorine atoms, 1 to 5 fluorine atoms, 1 to 7 fluorine atoms (e.g., n-propyl, i-propyl), 1 to 9 fluorine atoms (e.g., n-butyl, i-butyl, sec-butyl, t-butyl), 1 to 11 fluorine atoms (e.g., n-pentyl, t-pentyl, neopentyl, i-pentyl, sec-pentyl, 3-pentyl), 1 to 13 fluorine atoms, 1 to 15 fluorine atoms, 1 to 17 fluorine atoms, 1 to 19 fluorine atoms, 1 to 21 fluorine atoms, 1 to 23 fluorine atoms, 1 to 25 fluorine atoms, 1 to 27 fluorine atoms, 1 to 29 fluorine atoms, 1 to 31 fluorine atoms, 1 to 33 fluorine atoms, 1 to 35 fluorine atoms, 1 to 37 fluorine atoms, 1 to 39 fluorine atoms, 1 to 41 fluorine atoms, etc. of an alkyl group.

[0314] The number of fluorine atoms contained in the fluoroalkyl group may be 1 to the maximum number of substitutable atoms, for example, 1 to 41, 1 to 21, 1 to 19, 1 to 17, 1 to 15, 1 to 13, 1 to 11, 1 to 9, 1 to 7, 1 to 5, 1 to 3, etc.

[0315] As the "fluoroalkyl group", straight-chain or branched-chain fluoroalkyl groups such as monofluoromethyl, difluoromethyl, trifluoromethyl (CF3-), 2,2,2-trifluoroethyl, perfluoroethyl (C2F5-), tetrafluoropropyl (e.g., HCF2CF2CH2-), hexafluoropropyl (e.g., (CF3)2CH-), perfluoropropyl (e.g., CF3CF2CF2-, (CF3)2CF-), perfluorobutyl (e.g., CF3CF2CF2CF2-, (CF3)2CFCF2-, (CF3)3-), decafluorohexyl (e.g., HCF2CF2CF2CF2CF2-), octafluoropentyl (e.g., HCF2CF2CF2CF2CH2-), perfluoropentyl (e.g., CF3CF2CF2CF2CF2-, (CF3)2CFCF2CF2-), and perfluorohexyl (e.g., CF3CF2CF2CF2CF2CF2-, (CF3)2CFCF2CF2CF2-), perfluoroheptyl (e.g., CF3CF2CF2CF2CF2CF2CF2-, (CF3)2CFCF2CF2CF2CF2-), perfluorohexadecyl (e.g., CF3CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2-), and the like; cyclic C3-C10 fluoroalkyl groups (preferably perfluoroalkyl groups) such as fluorocyclopropyl, fluorocyclobutyl, fluorocyclopentyl, fluorocyclohexyl, fluorocycloheptyl, fluorocyclooctyl, fluoradiadamantyl, and the like can be exemplified.

[0316] In the present specification, unless otherwise specified, the "fluoroalkoxy group" is a straight-chain, branched-chain or cyclic alkoxy group in which at least one hydrogen atom is replaced with a fluorine atom. The fluoroalkoxy group also includes perfluoroalkoxy groups in which all the hydrogen atoms of the alkoxy group are replaced with fluorine atoms.

[0317] The number of carbon atoms of the fluoroalkoxy group can be, for example, 1 to 20, 1 to 10, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, or 1.

[0318] Examples of the fluoroalkoxy group include linear or branched C1-C20 fluoroalkoxy groups (e.g., C1-C10, preferably C1-C7, more preferably C1-C6, still more preferably C1-C4, particularly preferably C1-C3) having 1 to 3 fluorine atoms, e.g., methoxy, ethoxy having 1 to 5 fluorine atoms, propoxy (e.g., n-propoxy, isopropoxy) having 1 to 7 fluorine atoms, butoxy (e.g., n-butoxy, isobutoxy, sec-butoxy, t-butoxy) having 1 to 9 fluorine atoms, pentoxy (e.g., n-pentoxy, t-pentoxy, neopentoxy, isopentoxy, sec-pentoxy, 3-pentoxy) having 1 to 11 fluorine atoms, hexyloxy having 1 to 13 fluorine atoms, heptyloxy having 1 to 15 fluorine atoms, octyloxy having 1 to 17 fluorine atoms, nonyloxy having 1 to 19 fluorine atoms, decyloxy having 1 to 21 fluorine atoms, undecyloxy having 1 to 23 fluorine atoms, dodecyloxy having 1 to 25 fluorine atoms, tridecyloxy having 1 to 27 fluorine atoms, tetradecyloxy having 1 to 29 fluorine atoms, pentadecyloxy having 1 to 31 fluorine atoms, hexadecyloxy having 1 to 33 fluorine atoms, heptadecyloxy having 1 to 35 fluorine atoms, octadecyloxy having 1 to 37 fluorine atoms, nonadecyloxy having 1 to 39 fluorine atoms, icosyloxy having 1 to 41 fluorine atoms, etc.; cyclic C3-C10 fluoroalkoxy groups (e.g., C3-C6, C4-C6, C3-C5, C5-C6, C4-C8 fluoroalkoxy groups) such as fluorocyclopropoxy, fluorocyclobutyloxy, fluorocyclopentyloxy, fluorocyclohexyloxy, fluorocycloheptyloxy, fluorocyclooctyloxy, fluoroadamantyloxy, etc.

[0319] The number of fluorine atoms contained in the fluoroalkoxy group is 1 to the maximum number of substitutable atoms, e.g., 1 to 41, 1 to 21, 1 to 19, 1 to 17, 1 to 15, 1 to 13, 1 to 11, 1 to 9, 1 to 7, 1 to 5, 1 to 3, etc.

[0320] As the "fluoroalkoxy group", straight-chain or branched fluoroalkoxy groups such as monofluoromethoxy, difluoromethoxy, trifluoromethoxy (CF3O-), 2,2,2-trifluoroethoxy, perfluoroethoxy (C2F5O-), tetrafluoropropoxy (e.g., HCF2CF2CH2O-), hexafluoropropoxy (e.g., (CF3)2CHO-), perfluoropropoxy (e.g., CF3CF2CF2O-, (CF3)2CFO-), perfluorobutoxy (e.g., CF3CF2CF2CF2O-, (CF3)2CFCF2O-, (CF3)3O-), decafluorohexyloxy (e.g., HCF2CF2CF2CF2CF2O-), octafluoropentoxy (e.g., HCF2CF2CF2CF2CH2O-), perfluoropentoxy (e.g., CF3CF2CF2CF2CF2O-, (CF3)2CFCF2CF2O-), and perfluorohexyloxy (e.g., CF3CF2CF2CF2CF2CF2O-, (CF3)2CFCF2CF2CF2O-), perfluoroheptyloxy (e.g., CF3CF2CF2CF2CF2CF2CF2O-, (CF3)2CFCF2CF2CF2CF2O-), perfluorohexadecyloxy (e.g., CF3CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2CF2O-), and the like; cyclic C3-C10 fluoroalkoxy groups such as fluorocyclopropyloxy, fluorocyclobutyloxy, fluorocyclopentyloxy, fluorocyclohexyloxy, fluorocycloheptyloxy, fluorocyclooctyloxy, fluoroadamantyloxy, and the like (preferably perfluoroalkoxy groups).

[0321] In the present specification, as the "4- to 20-membered ring having 4 to 20 carbon atoms as ring-forming atoms", a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a cyclononane ring, a cyclodecane ring, a cycloundecane ring, a cyclododecane ring, and the like (preferably a cyclobutane ring, a cyclopentane ring, a cyclohexane ring) can be exemplified as alicyclic hydrocarbon rings (preferably a non-aromatic unsaturated hydrocarbon ring); a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, and the like can be exemplified as aromatic rings.

[0322] In the present specification, unless otherwise specified, as the "4- to 22-membered ring having 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms", there can be mentioned, for example, saturated heterocyclic rings having 1 oxygen atom as ring-constituting atoms such as an oxetane ring, a tetrahydrofuran ring, a tetrahydropyran ring, an oxepane ring, an oxocane ring, an oxonane ring, and the like; unsaturated heterocyclic rings having 1 oxygen atom as ring-constituting atoms such as an oxete ring, a furan ring, a pyran ring, an oxepene ring, an oxocene ring, an oxonene ring, and the like; saturated heterocyclic rings having 2 oxygen atoms as ring-constituting atoms such as a dioxetane ring, a dioxolane ring, a dioxane ring, a dioxepane ring, a dioxocane ring, and the like; unsaturated heterocyclic rings having 2 oxygen atoms as ring-constituting atoms such as a dioxete ring, a dioxolene ring, a dihydrodioxine ring, a dihydrodioxepene ring, a tetrahydrodioxene ring, and the like; unsaturated heterocyclic rings having a sulfur atom such as a thiophene ring, a thiane ring, a thiepane ring, a thiepin ring, a thieocane ring, a thionine ring, and the like; saturated heterocyclic rings having a sulfur atom such as a thietane ring, a tetrahydrothiophene ring, a thiane ring, a thiepane ring, a thieocane ring, a thionane ring, and the like.

[0323] In the present specification, unless otherwise specified, the "4- to 20-membered ring having 4 to 20 carbon atoms as ring-constituting atoms and having at least 1 fluorine atom" is a ring in which at least 1 of the hydrogen atoms bonded to the ring-constituting atoms of a 4- to 20-membered ring having 4 to 20 carbon atoms as ring-constituting atoms is substituted with a fluorine atom. The number of fluorine atoms is 1 to the maximum number of substitutable hydrogen atoms. A ring in which all of the hydrogen atoms bonded to the ring-constituting atoms are substituted with fluorine atoms (so-called perfluorinated ring) is preferred.

[0324] In the present specification, unless otherwise specified, the "4- to 22-membered ring having 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms and having at least 1 fluorine atom" is a ring in which at least 1 of the hydrogen atoms bonded to the ring-constituting atoms of a 4- to 22-membered ring having 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms is substituted with a fluorine atom. The number of fluorine atoms is 1 to the maximum number of substitutable hydrogen atoms. A ring in which all of the hydrogen atoms bonded to the ring-constituting atoms are substituted with fluorine atoms (so-called perfluorinated ring) is preferred.

[0325] In the present specification, unless otherwise specified, the "aryl group" can be a monocyclic, bicyclic or tricyclic aryl group. The aryl group can be a C6-C14 aryl group, a C6-C10 aryl group, a C6-C9 aryl group, a C6 aryl group. As the aryl group, there can be mentioned, for example, a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an indenyl group, a biphenyl group, an anthryl group, a phenanthryl group, and the like. The aryl group can have a methyl group, an ethyl group, a propyl group, and the like, and when a plurality of groups are present, they can be the same or different. The number of groups possessed by the aryl group can be 6, 5, 4, 3, 2, 1, 0.

[0326] In the present specification, unless otherwise specified, "an aryl group having a fluorine atom" is an aryl group in which at least one hydrogen atom is replaced with a fluorine atom, and includes a perfluoroaryl group in which all the hydrogen atoms of the aryl group are replaced with fluorine atoms, preferably a perfluoroaryl group.

[0327] The number of fluorine atoms possessed by the aryl group can be from 1 to the maximum number of substitutable hydrogen atoms, for example, from 1 to 16, from 1 to 15, from 1 to 14, from 1 to 13, from 1 to 12, from 1 to 11, from 1 to 10, from 1 to 9, from 1 to 5, from 1 to 3, and the like.

[0328] As the aryl group having a fluorine atom, a phenyl group having a fluorine atom, a 1-naphthyl group having a fluorine atom, a 2-naphthyl group having a fluorine atom, an indenyl group having a fluorine atom, a biphenyl group having a fluorine atom, an anthryl group having a fluorine atom, a phenanthryl group having a fluorine atom, and the like can be exemplified.

[0329] In the present specification, unless otherwise specified, examples of "alkali metals" include lithium, sodium, potassium, rubidium, cesium, and francium, preferred examples include lithium, sodium, and potassium, and more preferred examples include sodium and potassium.

[0330] In the present specification, unless otherwise specified, examples of "alkaline earth metals" include beryllium, magnesium, calcium, strontium, barium, and radium, and preferred examples include magnesium and calcium.

[0331] Method for producing fluorine-containing polymer (A)

[0332] One embodiment of the present application is a method for producing a fluorine-containing polymer (A). The production method of the present application can produce a fluorine-containing polymer having high ultraviolet transmittance. The production method of the present application includes a polymerization step and a filtration step, but a removal step of a polymerization initiator and / or a decomposition product thereof can or can not be included, and thus is a simple production method.

[0333] The production method of the present application includes a polymerization step of polymerizing a fluorine-containing monomer (M) in the presence of the fluorine-containing monomer (M) represented by the formula (M), a polymerization initiator (B), and a solvent (D) to produce a fluorine-containing polymer (A) in the form of a precipitate.

[0334]

[0335] [In the formula, R 1 R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group.

[0336] The above-described fluorine-containing polymer (A) contains a structural unit represented by the formula (A) (hereinafter sometimes referred to as structural unit (A)) as a main component.

[0337]

[0338] [In the formula, R 1 ~R 4 The same as above.

[0339] The value of the solubility index R (R A ) calculated based on the Hansen solubility parameter of the above solvent (D) and the Hansen solubility parameter of the above fluorine-containing polymer (A) can be 4 or more.

[0340] The value of the solubility index R (R B ) calculated based on the Hansen solubility parameter of the above solvent (D) and the Hansen solubility parameter of the above polymerization initiator (B) can be 9 or less when the mass ratio of fluorine atoms in the above polymerization initiator (B) is less than 50 mass%, and can be 6 or less when the above mass ratio is 50 mass% or more.

[0341] The value of the solubility index R (R C ) calculated based on the Hansen solubility parameter of the above solvent (D) and the Hansen solubility parameter of the decomposition product (C) of the above polymerization initiator (B) can be 9 or less when the mass ratio of fluorine atoms in the above decomposition product (C) is less than 50 mass%, and can be 6 or less when the above mass ratio is 50 mass% or more.

[0342] The above solubility index R is calculated by the following formula.

[0343] R = {4 x (δD1 - δD2) 2 + (δP1 - δP2) 2 + (δH1 - δH2) 2} 0.5

[0344] [In the formula, δD1, δP1, and δH1 respectively represent the dispersion term, the polarity term, and the hydrogen bond term in the Hansen solubility parameter of Element 1, and δD2, δP2, and δH2 respectively represent the dispersion term, the polarity term, and the hydrogen bond term in the Hansen solubility parameter of Element 2.]

[0345] Fluorine-containing polymer (A)

[0346] The fluorine-containing polymer (A) contains a structural unit represented by Formula (A) as a main component.

[0347]

[0348] [In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group.]

[0349] "Including structural units as main components" means that the proportion of such structural units in all structural units of the fluoropolymer (A) is more than 50 mol%.

[0350] The ratio of structural unit (A) in the fluoropolymer (A) is preferably 80 mol% or more, more preferably 90 mol% or more, and particularly preferably 100 mol%.

[0351] The structural unit (A) can be one or more types, preferably one to three types, more preferably one or two types, and particularly preferably one type.

[0352] In structural unit (A), R 1 ~R 4 It can be a fluorine atom, a C1-C5 straight-chain or branched perfluoroalkyl group, or a straight-chain or branched C1-C5 perfluoroalkoxy group, which can be independently fluorine atoms.

[0353] In structural unit (A), R 1 ~R 4 It can be a fluorine atom, a C1-C4 straight-chain or branched perfluoroalkyl group, or a straight-chain or branched C1-C4 perfluoroalkoxy group, which can be independently fluorine atoms.

[0354] In structural unit (A), R 1 ~R 4 It can be a fluorine atom, a C1-C3 straight-chain or branched perfluoroalkyl group, or a straight-chain or branched C1-C3 perfluoroalkoxy group, which can be independently fluorine atoms.

[0355] In structural unit (A), R 1 ~R 4 Preferably, each is independently composed of a fluorine atom, a trifluoromethyl atom, a perfluoroethyl atom, or a trifluoromethoxy atom.

[0356] In structural unit (A), R 1 ~R 4 More preferably, each is independently a fluorine atom, a trifluoromethyl atom, or a trifluoromethoxy atom.

[0357] R 1 ~R 4 At least one group is a fluorine atom, and the remaining groups can be C1-C2 perfluoroalkyl or C1-C2 perfluoroalkoxy, and the remaining groups are independent of each other when there are multiple groups.

[0358] R 1 ~R 4 At least two of the groups are fluorine atoms, and the remaining groups can be C1-C2 perfluoroalkyl or C1-C2 perfluoroalkoxy, and the remaining groups are independent of each other when there are multiple groups.

[0359] R 1 ~R4 at least 3 groups are fluorine atoms, and the remaining groups can be C1-C2 perfluoroalkyl groups or C1-C2 perfluoroalkoxy groups.

[0360] R 1 ~R 4 at least 3 groups are fluorine atoms, and the remaining groups can be C1-C2 perfluoroalkyl groups.

[0361] R 1 ~R 4 may all be fluorine atoms.

[0362] The structural unit (A) can be a structural unit represented by the following formula (Al) (hereinafter sometimes referred to as structural unit (Al)). In the present specification, a fluorine-containing polymer (A) containing the structural unit (Al) as a main component is sometimes referred to as fluorine-containing polymer (Al).

[0363]

[0364] In each of the groups of R 1 ~R 4 C1-C5 perfluoroalkyl groups are, for example, linear or branched C1-C5 fluoroalkyl groups, linear or branched C1-C4 fluoroalkyl groups, linear or branched C1-C3 fluoroalkyl groups, C1-C2 fluoroalkyl groups.

[0365] As the linear or branched C1-C5 fluoroalkyl groups, linear or branched C1-C5 perfluoroalkyl groups are preferable.

[0366] As the linear or branched C1-C4 fluoroalkyl groups, linear or branched C1-C4 perfluoroalkyl groups are preferable.

[0367] As the linear or branched C1-C3 fluoroalkyl groups, linear or branched C1-C3 perfluoroalkyl groups are preferable.

[0368] As the C1-C2 fluoroalkyl groups, C1-C2 perfluoroalkyl groups are preferable.

[0369] The fluorine-containing polymer (A) can contain, in addition to the structural unit (A) contained as a main component, a structural unit derived from a fluoroolefin (hereinafter sometimes referred to as fluoroolefin unit). The fluoroolefin unit can be one alone or a combination of two or more. The ratio of the fluoroolefin unit in the total structural units in the fluorine-containing polymer (A) can be 50 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%.

[0370] The fluoroolefin unit is a monomeric unit formed by polymerization of a monomer containing a fluorine atom and a carbon-carbon double bond.

[0371] The atoms constituting the fluoroolefin unit can be only fluorine atoms, halogen atoms other than fluorine atoms, carbon atoms, hydrogen atoms, and oxygen atoms.

[0372] The atoms constituting the fluoroolefin unit can be only fluorine atoms, halogen atoms other than fluorine atoms, carbon atoms, and hydrogen atoms.

[0373] The atoms constituting the fluoroolefin unit can be only fluorine atoms, carbon atoms, and hydrogen atoms.

[0374] The atoms constituting the fluoroolefin unit can be only fluorine atoms and carbon atoms.

[0375] The fluoroolefin unit includes a fluorine-containing perhaloolefin unit, a vinylidene fluoride unit (-CH2-CF2-), a trifluoroethylene unit (-CFH-CF2-), a pentafluoropropylene unit (-CFH-CF(CF3)-, -CF2-CF(CHF2)-), and a 1,1,1,2-tetrafluoro-2-propylene unit (-CH2-CF(CF3)-).

[0376] The fluorine-containing perhaloolefin unit is a structural unit formed after polymerization of a monomer containing fluorine atoms and a carbon-carbon double bond, and can contain halogen atoms other than fluorine atoms.

[0377] The fluorine-containing perhaloolefin unit includes a chlorotrifluoroethylene unit (-CFCI-CF2-), a tetrafluoroethylene unit (-CF2-CF2-), a hexafluoropropylene unit (-CF2-CF(CF3)-), a perfluoro(methyl vinyl ether) unit (-CF2-CF(OCF3)-), a perfluoro(ethyl vinyl ether) unit (-CF2-CF(OC2F5)-), a perfluoro(propyl vinyl ether) unit (-CF2-CF(OCF2C2F5)-), a perfluoro(butyl vinyl ether) unit (-CF2-CF(O(CF2)2C2F5)-), and a perfluoro(2,2-dimethyl-1,3-dioxolane) unit (-CF-CF (in the formula, A is a perfluorodioxolane ring formed together with the adjacent carbon atom shown in the formula, and represents a structure in which 2 trifluoromethyl groups are bonded to the 2-position carbon atom of the dioxolane ring).

[0378] The fluoroolefin unit includes a chlorotrifluoroethylene unit, a tetrafluoroethylene unit, a hexafluoropropylene unit, a perfluoro(methyl vinyl ether) unit, and a perfluoro(propyl vinyl ether) unit.

[0379] The fluorine-containing polymer (A) can contain one or more other structural units in addition to the structural unit (A) and the fluoroolefin unit, but is preferably free of them.

[0380] Such other structural units include CH2=CHRf (Rf represents a C1-C10 fluoroalkyl group) units, alkyl vinyl ether units (e.g., cyclohexyl vinyl ether units, ethyl vinyl ether units, butyl vinyl ether units, methyl vinyl ether units), alkenyl vinyl ether units (e.g., polyoxyethylene allyl ether units, ethyl allyl ether units), organosilicon compound units having a reactive α,β-unsaturated group (e.g., vinyltrimethoxysilane units, vinyltriethoxysilane units, vinyltris(methoxyethoxy)silane units), acrylic ester units (e.g., methyl acrylate units, ethyl acrylate units), methacrylic ester units (e.g., methyl methacrylate units, ethyl methacrylate units), vinyl ester units (e.g., vinyl acetate units, vinyl benzoate units, "VeoVa" (vinyl ester produced by Shell) units), and the like.

[0381] The ratio of the other structural units can be, for example, 0 to 20 mol%, 0 to 10 mol%, or the like, of the total structural units.

[0382] The mass average molecular weight of the fluorine-containing polymer (A) is, for example, in the range of 5,000 to 1,000,000, in the range of 10,000 to 1,000,000, in the range of 10,000 to 500,000, in the range of 90,000 to 350,000, or the like, preferably in the range of 10,000 to 750,000, more preferably in the range of 40,000 to 500,000, particularly preferably in the range of 70,000 to 350,000.

[0383] The lower limit of the mass average molecular weight of the fluorine-containing polymer (A) can be, for example, 5,000 or more, preferably 10,000 or more, more preferably 40,000 or more, particularly preferably 70,000 or more. The upper limit of the mass average molecular weight of the fluorine-containing polymer (A) can be, for example, 1,000,000 or less, preferably 750,000 or less, more preferably 500,000 or less, particularly preferably 350,000 or less. The above lower limit and upper limit can be appropriately combined.

[0384] The mass average molecular weight of the fluorine-containing polymer (A) is a value determined by a GPC (gel permeation chromatography) method (particularly the GPC method described in the examples).

[0385] Polymerization step

[0386] In the polymerization step, the above fluorine-containing monomer (M) is polymerized in the presence of the fluorine-containing monomer (M), the polymerization initiator (B), and the solvent (D). The fluorine-containing polymer (A) is generated in the form of a precipitate in the generated liquid.

[0387] Raw material monomer

[0388] The raw material monomers used in the polymerization step contain at least a fluorine-containing monomer (M). The fluorine-containing monomer (M) is a monomer corresponding to the structural unit (A) included as a main component in the fluorine-containing polymer (A). The fluorine-containing monomer (M) can be used alone or in combination of two or more kinds.

[0389] In the case where the manufactured fluorine-containing polymer (A) contains, in addition to the structural unit (A), a fluoroolefin unit and / or another structural unit, the raw material monomers contain, in addition to the monomer (M), a fluoroolefin monomer corresponding to the fluoroolefin unit and / or a monomer (hereinafter sometimes referred to as another monomer) corresponding to the other structural unit.

[0390] As understood by those skilled in the art, by causing a specific monomer to undergo a polymerization reaction, a fluorine-containing polymer (A) having a structural unit corresponding to the monomer can be obtained. Therefore, those skilled in the art can select an appropriate monomer in order to manufacture an intended fluorine-containing polymer (A). Thus, those skilled in the art can understand the monomer corresponding to the structural unit (A), the fluoroolefin monomer corresponding to the fluoroolefin unit, and the monomer corresponding to the other structural unit.

[0391] For example, the monomer corresponding to the structural unit (A) is a fluorine-containing monomer (M) represented by formula (M).

[0392]

[0393] [In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group.]

[0394] For example, the monomer corresponding to the structural unit (A1) is a compound represented by formula (M1) (hereinafter sometimes referred to as a fluorine-containing monomer (M1)).

[0395]

[0396] The fluorine-containing monomer (M) can sometimes contain a compound (N) therein. The amount of the compound (N) can be 0.0001 to 10% by mass, 0.0001 to 8% by mass, or 0.0001 to 6% by mass, relative to the mass of the raw material monomers. The compound (N) can be one alone or in combination of two or more kinds.

[0397] The above compound (N) is a compound represented by formula (N).

[0398]

[0399] [In the formula, R1 to R4 each independently represent a fluorine atom, a C1-C5 perfluoroalkyl group, or a C1-C5 perfluoroalkoxy group, and R 71and R 72 each independently represents a hydrogen atom or a fluorine atom, and in the case where either one of R 71 and R 72 is a hydrogen atom, the other represents a fluorine atom.

[0400] R 1 ~R 4 are as described above.

[0401] R 71 is a hydrogen atom and R 72 is a fluorine atom, and the case where R 71 is a fluorine atom and R 72 is a hydrogen atom.

[0402] More preferred compounds (N) are at least one compound selected from the group consisting of a compound represented by formula (N1) (hereinafter sometimes referred to as compound (N1)) and a compound represented by formula (N2) (hereinafter sometimes referred to as compound (N2)).

[0403]

[0404]

[0405] The ratio (e.g., molar ratio) of the fluorine-containing monomer (M), the fluoroolefin monomer, and the other monomer in the raw material monomers can be appropriately selected in accordance with the ratio (e.g., molar ratio) of the respective structural units constituting the fluorine-containing polymer (A) to be produced. Thus, as to the details of the fluorine-containing monomer (M), the fluoroolefin monomer, and the other monomer, those skilled in the art can understand from the above-described description on the structural units (A), the fluoroolefin unit, and the other structural unit corresponding to them, respectively.

[0406] As the fluoroolefin monomer, a monomer corresponding to the above-described fluoroolefin unit can be used. The fluoroolefin can be at least one selected from, for example, a fluorine-containing perhalogenated olefin, vinylidene fluoride, trifluoroethylene, pentafluoropropylene, and 1,1,1,2-tetrafluoro-2-propene. The fluoroolefin monomer is preferably at least one selected from chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(methyl vinyl ether), and perfluoro(propyl vinyl ether).

[0407] The above-described fluorine-containing perhalogenated olefin can be at least one selected from chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), perfluoro(butyl vinyl ether), and perfluoro(2,2-dimethyl-1,3-dioxolene).

[0408] Polymerization initiator (B)

[0409] As the polymerization initiator (B), any substance capable of polymerizing the raw material monomer can be used. The polymerization initiator (B) is preferably a peroxide, an azo compound, or the like, and is preferably a peroxide. The polymerization initiator (B) can be used alone or in combination of two or more.

[0410] The peroxide can be at least one compound (hereinafter sometimes referred to as compound (B)) selected from the group consisting of a compound represented by formula (Bl), a compound represented by formula (B2), and a compound represented by formula (B3).

[0411]

[0412] [In the formula, R 11 , R 12 , R 13 , and R 14 independently represent a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 , and R 12 may be linked to each other, and 4 to 20 carbon atoms can form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom,

[0413] R 13 , and R 14 may be linked to each other, and 4 to 20 carbon atoms can form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom can form a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom.

[0414]

[0415] [In the formula, R 15 , and R 16 independently represent a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom.]

[0416]

[0417] [In the formula, R 17 , and R 18respectively, C1-C20 linear or branched alkyl, C1-C20 linear or branched fluoroalkyl, C4-C8 cyclic alkyl, C4-C8 cyclic fluoroalkyl, or C4-C14 aryl which can have a fluorine atom, and the above alkyl and fluoroalkyl can each have an etheric oxygen atom.

[0418] In formula (B1), R 11 and R 13 are the same and R 12 and R 14 are the same, or a ring structure formed by linking R 11 and R 12 to each other is the same as a ring structure formed by linking R 13 and R 14 to each other.

[0419] In formula (B1), R 11 , R 12 , R 13 and R 14 may each independently be:

[0420] a fluorine atom,

[0421] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0422] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0423] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0424] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0425] or a 4- to 8-membered perfluoro cycloalkane ring, a perfluoro benzene ring, a perfluoro naphthalene ring, a perfluoro oxacyclopentane ring, or a perfluoro dioxacyclopentane ring formed by linking R 11 and R 12 to each other, and

[0426] a 4- to 8-membered perfluoro cycloalkane ring, a perfluoro benzene ring, a perfluoro naphthalene ring, a perfluoro oxacyclopentane ring, or a perfluoro dioxacyclopentane ring formed by linking R 13 and R 14 to each other.

[0427] In formula (B1), R 11 , R 12 , R 13 and R 14 may each independently be:

[0428] a fluorine atom,

[0429] — (CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0430] — (CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0431] — O— (CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0432] — O— (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0433] or R 11 and R 12 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring, or perfluoro naphthalene ring linked to each other, and

[0434] R 13 and R 14 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring, or perfluoro naphthalene ring linked to each other.

[0435] In formula (Bl), R 11 , R 12 , R 13 and R 14 may be independently, respectively:

[0436] — (CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0437] — (CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0438] — O— (CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0439] — O— (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0440] or R 11 and R 12 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring, or perfluoro naphthalene ring linked to each other, and

[0441] R 13 and R 14 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring, or perfluoro naphthalene ring linked to each other.

[0442] In formula (B1), R 11 , R 12 , R 13 and R 14 may be each independently:

[0443] a fluorine atom,

[0444] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 2),

[0445] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 2),

[0446] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 2), or

[0447] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 2),

[0448] or R 11 and R 12 are linked to each other to form a 4- to 6-membered perfluoro cycloalkane ring, a perfluoro benzene ring or a perfluoro naphthalene ring, and

[0449] R 13 and R 14 are linked to each other to form a 4- to 6-membered perfluoro cycloalkane ring, a perfluoro benzene ring or a perfluoro naphthalene ring.

[0450] In formula (B1), R 11 , R 12 , R 13 and R 14 may be each independently:

[0451] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 2),

[0452] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 2),

[0453] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 2), or

[0454] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 2),

[0455] or R 11 and R 12 are linked to each other to form a 4- to 6-membered perfluoro cycloalkane ring, a perfluoro benzene ring or a perfluoro naphthalene ring.

[0456] R 13 R 14 4 to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring or perfluoro naphthalene ring linked to each other.

[0457] In formula (B1), R 11 and R 13 may be a fluorine atom, R 12 and R 14 may be independently of each other:

[0458] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0459] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0460] -O-(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0461] -O-(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5.

[0462] In formula (B2), preferably R 15 and R 16 are the same.

[0463] In formula (B2), preferably the alkyl group and the fluoroalkyl group do not have an etheric oxygen atom.

[0464] In formula (B2), the C4 to C8 cyclic alkyl group can be a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group.

[0465] In formula (B2), the C4 to C8 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group.

[0466] In formula (B2), the C4 to C8 cyclic fluoroalkyl group can be a C4 to C6 cyclic fluoroalkyl group. The C4 to C6 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group.

[0467] In formula (B2), the C4 to C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group which can have a fluorine atom.

[0468] In formula (B2), the C4 to C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0469] In formula (B2), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group.

[0470] In formula (B2), R 15 and R 16 may be independently of each other a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom. The above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0471] In formula (B2), R 15 and R 16 may be independently of each other a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group, a phenyl group which can have a fluorine atom, a naphthyl group which can have a fluorine atom, an anthryl group which can have a fluorine atom, or a phenanthryl group which can have a fluorine atom.

[0472] In formula (B2), R 15 and R 16 may be independently of each other a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a phenyl group, a naphthyl group, a phenyl group which has a fluorine atom, or a naphthyl group which has a fluorine atom.

[0473] In formula (B2), R 15 and R 16 may be independently of each other a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group.

[0474] In formula (B3), it is preferable that R 17 and R 18 be different.

[0475] In formula (B3), when R 17 is an alkyl group and a fluoroalkyl group, it is preferable that it not have an etheric oxygen atom.

[0476] In formula (B3), the C4-C8 cyclic alkyl group can be a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group.

[0477] In formula (B3), the C4-C8 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group.

[0478] In formula (B3), the C4-C8 cyclic fluoroalkyl group can be a C4-C6 cyclic fluoroalkyl group. The C4-C6 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group.

[0479] In formula (B3), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0480] In formula (B3), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0481] In formula (B3), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group.

[0482] In formula (B3), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group.

[0483] In formula (B3), R 17 and R 18 may be independently of each other a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom. The above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0484] In formula (B3), R 17 and R 18 may be independently of each other a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group, a phenyl group which can have a fluorine atom, a naphthyl group which can have a fluorine atom, an anthryl group which can have a fluorine atom, or a phenanthryl group which can have a fluorine atom. The above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0485] In formula (B3), R 17 and R 18 may be independently of each other a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a phenyl group, a naphthyl group, a phenyl group which has a fluorine atom, or a naphthyl group which has a fluorine atom. The above alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

[0486] In formula (B3), R 17may be a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 9 carbon atoms, a linear fluoroalkyl group having 1 to 6 carbon atoms, a branched fluoroalkyl group having 3 to 6 carbon atoms, or a phenyl group.

[0487] In formula (B3), R 17 may be a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group.

[0488] In formula (B3), R 18 may be a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, a linear fluoroalkyl group having 1 to 6 carbon atoms, or a branched fluoroalkyl group having 3 to 6 carbon atoms. The above alkyl group and fluoroalkyl group can each have an etheric oxygen atom.

[0489] In formula (B3), R 18 may be a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

[0490] In formula (B3), R 17 may be a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 may be a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

[0491] Examples of the compound (B1) include compounds represented by the following structural formulas. In the following structural formulas, ml represents an integer of 0 to 6, m2 represents an integer of 0 to 6, m3 represents an integer of 0 to 2, m4 represents an integer of 0 to 2, and m3 and m4 can be the same or different.

[0492]

[0493] Preferred examples of the compound (B1) include bis (2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7- dodecafluoro-1-oxoheptyl) peroxide (DHP) and bis (cyclohexylcarbonyl) peroxide.

[0494] Examples of the compound (B2) include di-sec-butyl peroxydicarbonate, di-n-propyl peroxydicarbonate (NPP), diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, bistrifluoromethyl peroxydicarbonate, bis-pentafluoroethyl peroxydicarbonate, bis-heptafluoro-n-propyl peroxydicarbonate, and bis-heptafluoroisopropyl peroxydicarbonate.

[0495] Preferred examples of the compound (B2) include diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate (NPP), and bistrifluoromethyl peroxydicarbonate.

[0496] Examples of the compound (B3) include t-butyl peroxy acetate (TBPOA), t-butyl peroxy pivalate, t-hexyl peroxy pivalate, t-butyl peroxy neodecanoate, t-butyl peroxy benzoate, trifluoromethyl-2,2,2-trifluoromethyl peroxy acetate (CF3COOOCF3), heptafluoroisopropyl-2,2,2-trifluoromethyl peroxy acetate ((CF3)2CFCOOOCF3).

[0497] Preferred examples of the compound (B3) include t-butyl peroxy acetate (TBPOA), t-butyl peroxy benzoate, trifluoromethyl-2,2,2-trifluoromethyl peroxy acetate (CF3COOOCF3).

[0498] Decomposition product (C) of the polymerization initiator (B)

[0499] The decomposition product (C) of the polymerization initiator (B) is generated by decomposition of the polymerization initiator (B) in the polymerization step. The decomposition product (C) is contained in the polymerization reaction liquid and the precipitate after the polymerization reaction. The decomposition product (C) in the polymerization reaction liquid is separated from the precipitate in the filtration step. The decomposition product (C) can be used alone or in combination of two or more.

[0500] The decomposition product (C) can be at least one compound (hereinafter sometimes referred to as a compound (C)) selected from a compound represented by formula (C1) (hereinafter sometimes referred to as a compound (C1)), a compound represented by formula (C2) (hereinafter sometimes referred to as a compound (C2)), and a compound represented by formula (C3) (hereinafter sometimes referred to as a compound (C3)).

[0501]

[0502] [In the formula, R 41 and R 42 respectively independently represent a fluorine atom, a C1-C20 alkyl group, or a C1-C20 fluoroalkyl group,

[0503] The above alkyl group and fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other, and form a 4- to 20-membered ring having at least one fluorine atom with 4 to 20 carbon atoms as ring-forming atoms, or a 4- to 22-membered ring having at least one fluorine atom with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-forming atoms,

[0504] R 43 represents a fluorine atom or a hydroxyl group.

[0505]

[0506] [In the formula, R45 R represents a C1-C20 straight-chain or branched alkyl group, a C1-C20 straight-chain or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group that may have a fluorine atom. 46 This indicates a fluorine atom or a hydroxyl group.

[0507]

[0508] [In the formula, R] 47 This refers to straight-chain or branched alkyl groups (C1-C20), straight-chain or branched fluoroalkyl groups (C1-C20), cyclic alkyl groups (C4-C8), cyclic fluoroalkyl groups (C4-C8), or aryl groups (C4-C14) that may have fluorine atoms. The aforementioned alkyl and fluoroalkyl groups may each have ether-like oxygen atoms.

[0509] R 49 This indicates a fluorine atom or a hydroxyl group.

[0510] In equation (C1), R 41 and R 42 They can be considered independently as follows:

[0511] Fluorine atom,

[0512] -(CF2) n1 CF3 (where n1 represents an integer from 0 to 5),

[0513] -(CF2) n2 CF2H (where n2 represents an integer from 0 to 5),

[0514] -O-(CF2) n3 CF3 (where n3 represents an integer from 0 to 5), or

[0515] -O-(CF2) n4 CF2H (where n4 represents an integer from 0 to 5).

[0516] Or R 41 and R 42 Interconnected 4- to 8-membered perfluorocycloalkane rings, perfluorobenzene rings, perfluoronaphthalene rings, perfluorooxocyclopentane rings, or perfluorodioxocyclopentane rings.

[0517] R 43 It can be a fluorine atom or a hydroxyl group.

[0518] In equation (C1), R 41 and R 42 They can be considered independently as follows:

[0519] Fluorine atom,

[0520] -(CF2)n1 CF3(wherein nl represents an integer of 0 to 5),

[0521] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0522] -(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0523] -(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0524] or R 41 and R 42 a 4- to 6-membered perfluoro cycloalkane ring, a perfluoro benzene ring or a perfluoro naphthalene ring linked to each other,

[0525] R 43 may be a fluorine atom or a hydroxyl group.

[0526] In formula (C1), R 41 and R 42 may be independently, respectively:

[0527] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 5),

[0528] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 5),

[0529] -(CF2) n3 CF3(wherein n3 represents an integer of 0 to 5), or

[0530] -(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0531] or R 41 and R 42 a 4- to 6-membered perfluoro cycloalkane ring, a perfluoro benzene ring or a perfluoro naphthalene ring linked to each other,

[0532] R 43 may be a fluorine atom or a hydroxyl group.

[0533] In formula (C1), R 41 and R 42 may be independently, respectively:

[0534] a fluorine atom,

[0535] -(CF2) n1 CF3(wherein nl represents an integer of 0 to 2),

[0536] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 2),

[0537] -(CF2) n3 CF3 (wherein n3 represents an integer of 0 to 2), or

[0538] -(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 2),

[0539] or R 41 and R 42 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring or perfluoro naphthalene ring linked to each other,

[0540] R 43 may be a fluorine atom or a hydroxyl group.

[0541] In formula (C1), R 41 and R 42 may be independently each other:

[0542] -(CF2) n1 CF3 (wherein n1 represents an integer of 0 to 2),

[0543] -(CF2) n2 CF2H (wherein n2 represents an integer of 0 to 2),

[0544] -(CF2) n3 CF3 (wherein n3 represents an integer of 0 to 2), or

[0545] -(CF2) n4 CF2H (wherein n4 represents an integer of 0 to 2),

[0546] or R 41 and R 42 4- to 6-membered perfluoro cycloalkane ring, perfluoro benzene ring or perfluoro naphthalene ring linked to each other,

[0547] R 43 may be a fluorine atom or a hydroxyl group.

[0548] In formula (C1), R 41 may be a fluorine atom,

[0549] R 42 may be:

[0550] -(CF2) n1 CF3 (wherein n1 represents an integer of 0 to 5),

[0551] -(CF2) n2CF2H (wherein n2 represents an integer of 0 to 5),

[0552] — O — (CF2) n3 CF3 (wherein n3 represents an integer of 0 to 5), or

[0553] — O — (CF2) n4 CF2H (wherein n4 represents an integer of 0 to 5),

[0554] R 43 may be a fluorine atom or a hydroxyl group.

[0555] In formula (C2), the alkyl group and the fluoroalkyl group preferably do not have an etheric oxygen atom.

[0556] In formula (C2), the C4-C8 cyclic alkyl group can be a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group.

[0557] In formula (C2), the C4-C8 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group.

[0558] In formula (C2), the C4-C8 cyclic fluoroalkyl group can be a C4-C6 cyclic fluoroalkyl group. The C4-C6 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group.

[0559] In formula (C2), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0560] In formula (C2), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0561] In formula (C2), the C4-C14 aryl group which can have a fluorine atom can be a phenyl group, a naphthyl group.

[0562] In formula (C2), R 45 may be a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 46 may be a fluorine atom or a hydroxyl group.

[0563] In formula (C2), R 45may be a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a phenyl group, a naphthyl group, a phenyl group having a fluorine atom, or a naphthyl group having a fluorine atom, R 46 may be a fluorine atom or a hydroxyl group.

[0564] In formula (C2), R 45 may be a C1-C7 linear or branched alkyl group, a C1-C7 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a phenyl group, a naphthyl group, a phenyl group having a fluorine atom, or a naphthyl group having a fluorine atom, R 46 may be a fluorine atom or a hydroxyl group.

[0565] In formula (C2), R 45 may be a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 may be a fluorine atom or a hydroxyl group.

[0566] In formula (C3), R 47 is an alkyl group and a fluoroalkyl group, it is preferable that there be no etheric oxygen atom.

[0567] In formula (C3), the C4-C8 cyclic alkyl group can be a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group.

[0568] In formula (C3), the C4-C8 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group.

[0569] In formula (C3), the C4-C8 cyclic fluoroalkyl group can be a C4-C6 cyclic fluoroalkyl group. The C4-C6 cyclic fluoroalkyl group can be a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group.

[0570] In formula (C3), the C4-C14 aryl group having a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0571] In formula (C3), the C4-C14 aryl group having a fluorine atom can be a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group.

[0572] In formula (C3), the C4-C14 aryl group having a fluorine atom can be a phenyl group, a naphthyl group.

[0573] In formula (C3), the C4-C14 aryl group having a fluorine atom can be a phenyl group, a naphthyl group.

[0574] In formula (C3), R 47 may be a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the above alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 may be a fluorine atom or a hydroxyl group.

[0575] In formula (C3), R 47 may be a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a fluorocycloheptyl group, a fluorocyclooctyl group, a phenyl group which can have a fluorine atom, a naphthyl group which can have a fluorine atom, an anthryl group which can have a fluorine atom, a phenanthryl group which can have a fluorine atom, the above alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 may be a fluorine atom or a hydroxyl group.

[0576] In formula (C3), R 47 may be a C1-C9 linear or branched alkyl group, a C1-C9 linear or branched fluoroalkyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a fluorocyclobutyl group, a fluorocyclopentyl group, a fluorocyclohexyl group, a phenyl group, a naphthyl group, a phenyl group which has a fluorine atom, a naphthyl group which has a fluorine atom, the above alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 may be a fluorine atom or a hydroxyl group.

[0577] In formula (C3), R 47 may be a C1-C6 linear alkyl group, a C3-C9 branched alkyl group, a C1-C6 linear fluoroalkyl group, a C3-C6 branched fluoroalkyl group, a phenyl group, R 49 may be a fluorine atom or a hydroxyl group.

[0578] In formula (C3), R 47 may be a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 may be a fluorine atom or a hydroxyl group.

[0579] In formula (C3), R 49 may be a C1-C6 linear alkyl group, a C3-C6 branched alkyl group, a C1-C6 linear fluoroalkyl group, a C3-C6 branched fluoroalkyl group, the above alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 may be a fluorine atom or a hydroxyl group.

[0580] In formula (C3), R 49may be a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R

[0581] In formula (C3), R 47 may be a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 may be a fluorine atom or a hydroxyl group.

[0582] Examples of the compound (C1) include compounds represented by the following structural formulas. In the following structural formulas, m1 represents an integer of 0 to 6, m2 represents an integer of 0 to 6, m3 represents an integer of 0 to 2, m4 represents an integer of 0 to 2, m3 and m4 can be the same or different, R 43 may be a fluorine atom or a hydroxyl group.

[0583]

[0584] Preferred examples of the compound (C1) include 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-l-oxoheptyl carboxylic acid, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-l-oxoheptyl fluorides, cyclohexyl carboxylic acid, cyclohexyl fluorides.

[0585] Examples of the compound (C2) include n-propyloxy carboxylic acid, n-propyloxy fluorides, sec-butyloxy carboxylic acid, sec-butyloxy fluorides, isopropyloxy carboxylic acid, isopropyloxy fluorides, 2-ethylhexyloxy carboxylic acid, 2-ethylhexyloxy fluorides, trifluoromethyloxy carboxylic acid, trifluoromethyloxy fluorides, pentafluoroethyloxy carboxylic acid, pentafluoroethyloxy fluorides, heptafluoro-n-propyloxy carboxylic acid, heptafluoro-n-propyloxy fluorides, heptafluoroisopropyloxy carboxylic acid, heptafluoroisopropyloxy fluorides.

[0586] Preferred examples of the compound (C2) include n-propyloxy carboxylic acid, n-propyloxy fluorides, isopropyloxy carboxylic acid, isopropyloxy fluorides, trifluoromethyloxy carboxylic acid, trifluoromethyloxy fluorides.

[0587] Examples of the compound (C3) include acetic acid, methyl fluorides t-butyl carboxylic acid, t-butyl fluorides, neononyl carboxylic acid, neononyl fluorides, benzoic acid, phenyl fluorides, heptafluoroisopentyl carboxylic acid, heptafluoroisopentyl fluorides, trifluorocarboxylic acid, trifluorofluorides.

[0588] Preferred examples of the compound (C3) include acetic acid, methyl fluorides, benzoic acid, phenyl fluorides, trifluorocarboxylic acid, trifluorofluorides.

[0589] Solvent (D)

[0590] The fluorine-containing monomer (M) is polymerized in a solvent (D). The solvent is not particularly limited as long as it can dissolve the raw material monomer and precipitate the fluorine-containing polymer (A). Therefore, as the solvent (D), a known solvent used when the fluorine-containing polymer (A) is produced by the use of precipitation polymerization can be used. The solvent (D) can be used alone or in combination of two or more.

[0591] The solvent (D) can be an aprotic solvent. As the aprotic solvent, a non-perfluorinated solvent can be exemplified.

[0592] The non-perfluorinated solvent is a solvent having at least a fluorine atom, a carbon atom and a hydrogen atom among aprotic solvents. As the non-perfluorinated solvent, a hydrofluorocarbon, a hydrofluoroether, a fluorine-containing alcohol and an olefin compound having at least one chlorine atom, etc. can be exemplified. The non-perfluorinated solvent can be used alone or in combination of two or more.

[0593] The hydrofluorocarbon is, for example, a C3-C8 hydrofluorocarbon. Examples of the hydrofluorocarbon include CF3CH2CF2H, CF3CH2CF2CH3, CF3CHFCHFC2F5, 1,1,2,2,3,3,4-heptafluorocyclopentane, CF3CF2CF2CF2CH2CH3, CF3CF2CF2CF2CF2CHF2and CF3CF2CF2CF2CF2CF2CH2CH3.

[0594] The hydrofluorocarbon is, for example, a C3-C8 hydrofluorocarbon. Examples of the hydrofluorocarbon include CF3CH2CF2H, CF3CH2CF2CH3, CF3CHFCHFC2F5, 1,1,2,2,3,3,4-heptafluorocyclopentane, CF3CF2CF2CF2CH2CH3, CF3CF2CF2CF2CF2CHF2and CF3CF2CF2CF2CF2CF2CH2CH3.

[0595] The hydrofluoroether is, for example, a fluorine-containing ether.

[0596] The global warming potential (GWP) of the hydrofluoroether is preferably 600 or less, more preferably 400 or less, and particularly preferably 300 or less. The lower limit of the global warming potential (GWP) of the hydrofluoroether can be 1 or more or 5 or more.

[0597] Examples of hydrofluoroethers include CF3CF2CF2CF2OCH3, CF3CF2CF(CF3)OCH3, CF3CF(CF3)CF2OCH3, CF3CF2CF2CF2OC2H5, CF3CH2OCF2CHF2, (CF3)2CHOCH3, (CF3)2CFOCH3, CHF2CF2OCH2CF3, CHF2CF2CH2OCF2CHF2, CF3CHFCF2OCH3, CF3CHFCF2OCF3, Trifluoromethyl-1,2,2,2-tetrafluoroethyl ether (HFE-227me), Difluoromethyl-1,1,2,2,2-heptafluoroethyl ether (HFE-227mc), Trifluoromethyl-1,1,2,2-tetrafluoroethyl ether (HFE-227pc), Difluoromethyl-2,2,2-trifluoroethyl ether (HFE-245mf), 2,2-Difluoroethyl trifluoromethyl ether (HFE-245pf), 1,1,2,3,3-Hexafluoropropyl methyl ether (CF3CHFCF2OCH3), 1,1,1,2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether (CHF2CF2OCH2CF3), and 1,1,1,3,3,3-Hexafluoro-2-methoxypropane ((CF3)2CHOCH3).

[0598] Preferred examples of hydrofluoroethers include CF3CH2OCF2CHF2, 1,1,2,3,3-Hexafluoropropyl methyl ether (CF3CHFCF2OCH3, HFE-356mec), 1,1,1,2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether (CHF2CF2OCH2CF3), and 1,1,1,3,3,3-Hexafluoro-2-methoxypropane ((CF3)2CHOCH3).

[0599] Fluorine-containing alcohols are compounds in which at least one hydrogen atom of an alcohol is replaced with a fluorine atom.

[0600] Examples of fluorine-containing alcohols include CF3CH2OH, CF3CF2CH2OH, CF3(CF2)2CH2OH, CF3(CF2)3(CH2)2OH, CF3(CF2)3(CH2)3OH, CF3(CF2)5(CH2)2OH, CF3(CF2)5(CH2)3OH, CF2HCF2CH2OH, CF2H(CF2)3CH2OH, CF2H(CF2)5CH2OH, (CF3)2CHOH, CF3CHFCF2CH2OH, HOCH2(CF2)4CH2OH, HOCH2(CF2)6CH2OH.

[0601] Preferred examples of fluorine-containing alcohols preferably include CF3CF2CH2OH, CF2HCF2CH2OH, CF2H(CF2)3CH2OH, (CF3)2CHOH.

[0602] The olefin compound having at least one chlorine atom is a C2-C4 (preferably C2-C3) olefin compound having at least one chlorine atom in its structure. The olefin compound having at least one chlorine atom is a compound in which at least one of the hydrogen atoms bonded to the carbon atoms of a hydrocarbon having 2 to 4 carbon atoms having 1 or 2 (preferably 1) double bonds is replaced with a chlorine atom.

[0603] The number of chlorine atoms is 1 to the maximum number of substitutable atoms. The number of chlorine atoms may be, for example, 1, 2, 3, 4, 5, or the like.

[0604] The olefin compound having at least one chlorine atom can also contain at least 1 (for example, 1, 2, 3, 4, 5, or the like) fluorine atom.

[0605] Examples of the olefin compound having at least one chlorine atom include CH2=CHCl, CHCl=CHCl, CCl2=CHCl, CCl2=CCl2, CF3CH=CHCl, CHF2CF=CHCl, CFH2CF=CHCl, CF3CCl=CFCl, CF2HCl=CFCl, and CFH2Cl=CFCl.

[0606] Preferred examples of the olefin compound having at least one chlorine atom include CHCl=CHCl, CHF2CF=CHCl, CF3CH=CHCl, and CF3CCl=CFCl.

[0607] As the solvent (D), from the viewpoint of small environmental burden at the time of use and easy removal from the polymer by distillation, a hydrofluoroether, a fluorine-containing alcohol is preferred.

[0608] The global warming potential (GWP) of the solvent (D) can be 600 or less, 400 or less, or the like, preferably 375 or less, more preferably 350 or less, and particularly preferably 0. The lower limit of the global warming potential (GWP) of the solvent (D) can be 1 or more or 5 or more.

[0609] The amount of the fluorine-containing monomer (M) used in the polymerization step can be appropriately determined in correspondence with the ratio of the structural unit (A) in the desired fluorine-containing polymer (A) or the like. For example, the amount of the fluorine-containing monomer (M) is 50 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, and particularly preferably 100 mol% relative to the total number of moles of the raw material monomers.

[0610] When fluorinated olefin monomers and / or other monomers are used in addition to fluorinated monomers (M), the amounts of these monomers can be appropriately determined corresponding to the ratio of fluorinated olefin units to other structural units in the desired fluorinated polymer (A). For example, the amount of fluorinated olefin monomer relative to the total moles of the raw material monomers can be 50 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%; the amount of other monomers relative to the total moles of the raw material monomers can be 0 to 20 mol%, 0 to 10 mol%, etc., preferably 20 mol% or less, more preferably 10 mol% or less.

[0611] Regarding the amount of polymerization initiator (B) used in the polymerization process, for example, relative to 1g of all raw material monomers, it can be in the range of 0.0001g to 0.05g, preferably in the range of 0.0001g to 0.01g, and more preferably in the range of 0.0005g to 0.008g.

[0612] Regarding the amount of solvent (D) used in the polymerization process, for example, when the total amount of raw material monomers is set to 100% by mass, it can be in the range of 20% by mass to 300% by mass, preferably in the range of 35% by mass to 250% by mass, and more preferably in the range of 50% by mass to 300% by mass.

[0613] The polymerization temperature is, for example, in the range of -10°C to 160°C, preferably in the range of 0°C to 160°C, and more preferably in the range of 0°C to 100°C.

[0614] The polymerization reaction can be carried out at a temperature 20°C higher than the boiling point of either the fluorinated monomer (M) or the solvent (D), and at a temperature 20°C higher than the 10-hour half-life temperature of the polymerization initiator. In this case, the lower limit of the temperature can be, for example, -10°C, preferably 0°C.

[0615] There are no particular limitations on the reaction time of the polymerization reaction as long as the fluoropolymer (A) can be generated. It is preferably in the range of 0.5 hours to 72 hours, more preferably in the range of 1 hour to 48 hours, and even more preferably in the range of 3 hours to 30 hours.

[0616] The polymerization reaction can be carried out with or without an inert gas (e.g., nitrogen), preferably with the presence of the gas.

[0617] Polymerization reactions can be carried out under reduced pressure, atmospheric pressure, or pressurized conditions.

[0618] In the polymerization step, the order of addition and mixing of the raw material monomer, the polymerization initiator (B), and the solvent (D) is not particularly limited. For example, the raw material monomer can be added to the solvent (D) containing the polymerization initiator (A), or the polymerization initiator can be added to the solvent (D) containing the raw material monomer.

[0619] The fluorine-containing polymer (A) produced by the polymerization reaction can be isolated or purified by a conventional method such as extraction, dissolution, concentration, filtration, precipitation, dehydration, adsorption, chromatography, or a combination thereof, as desired. From the viewpoint of convenience, filtration is preferred.

[0620] Filtering step

[0621] The manufacturing method of the present application can include a filtering step. In the filtering step, the polymerization product liquid is removed by filtering the precipitate and the polymerization product liquid produced in the polymerization step, and the fluorine-containing polymer (A) can be obtained. The solid obtained by the filtration is the fluorine-containing polymer (A) having a very low amount of the polymerization initiator (B) and / or the decomposition product (C) mixed therewith. In the case where the amount of the mixed substance is further reduced, the solid obtained by the filtration can be washed with a solvent (e.g., the polymerization solvent (B)). Thus, in the manufacturing method of the present application, the fluorine-containing polymer (A) having a very low amount of the polymerization initiator (B) and / or the decomposition product (C) mixed therewith can be obtained by only the filtering step, which is a simple procedure, after the polymerization step, or by further including a washing step in which the solid obtained by the filtration is washed with a solvent (e.g., the polymerization solvent (B)).

[0622] As the filter material, a resin product of polyethylene, polypropylene, polyester, nylon, polytetrafluoroethylene, or the like, a cotton fiber product of cellulose or the like, and a metal product of SUS or the like can be used. The pore size of the filter material can be 1 μm, 10 μm, 100 μm, 300 μm, 500 μm, 1000 μm, or the like. The pore size can be a range of values obtained by appropriately combining two of these values. The pore size can be, for example, 1 to 1000 μm, 1 to 500 μm, 1 to 300 μm, 1 to 100 μm, 10 to 1000 μm, 100 to 1000 μm, 300 to 1000 μm. The filtering step can be performed under reduced pressure, at atmospheric pressure, or under pressurized conditions.

[0623] Hansen solubility parameter

[0624] The Hildebrand solubility parameter (δ) is a physical value defined by the square root of the cohesive energy density, and is one of the indices indicating the solubility behavior of a substance, and is expressed as "SP". The SP is divided into a dispersion force term (δD D ), a polarity term (δP P ), and a hydrogen bond term (δH H) These three parts and the parameter that takes into account the polarity of the substance, which is the Hansen solubility parameter, expressed as "HSP". The relationship between the two is expressed by "delta 2 = delta D 2 + delta P 2 + delta H 2 ".

[0625] In the production method of the present application, the Hansen solubility parameter (hereinafter sometimes referred to simply as "solubility parameter" or "HSP") of each of the fluorine-containing polymer (A), the polymerization initiator (B), the decomposition product (C), and the solvent (D) has a specific relationship. Thereby, the amount of the polymerization initiator (B) and / or the decomposition product (C) mixed in the fluorine-containing polymer (A) produced by polymerization can be reduced.

[0626] The HSP of each of the fluorine-containing polymer (A), the polymerization initiator (B), the decomposition product (C), and the solvent (D) can be any value determined experimentally by a solubility test (which includes a literature value, a database value), or a value estimated from the chemical structure of the substance using a HSP-specific software (e.g., HSPiP).

[0627] Solubility index R

[0628] The solubility index R is calculated from the following formula, and corresponds to the distance between the HSP of Element 1 and the HSP of Element 2. When the distance is small, i.e., when R is small, Element 1 and Element 2 are considered to be in an easily soluble relationship.

[0629] R = {4 x (delta D1 - delta D2) 2 + (delta P1 - delta P2) 2 + (delta H1 - delta H2) 2} 0.5

[0630] [In the formula, delta D1, delta P1, and delta H1 represent the dispersion term, the polarity term, and the hydrogen bond term, respectively, of the Hansen solubility parameter of Element 1, and delta D2, delta P2, and delta H2 represent the dispersion term, the polarity term, and the hydrogen bond term, respectively, of the Hansen solubility parameter of Element 2.]

[0631] The value of the solubility index R (R A ) calculated based on the HSP of the solvent (D) and the HSP of the fluorine-containing polymer (A) can be 4 or more.

[0632] When the mass ratio of fluorine atoms in the polymerization initiator (B) is less than 50 mass%, the value of the solubility index R (R B ) calculated based on the HSP of the solvent (D) and the HSP of the polymerization initiator (B) can be 9 or less, preferably 8 or less.

[0633] When the mass ratio of fluorine atoms in the polymerization initiator (B) is 50 mass% or more, the value of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the polymerization initiator (B) (R B ) can be 6 or less, preferably 5 or less.

[0634] When the mass ratio of fluorine atoms in the decomposed substance (C) is less than 50 mass%, the value of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the decomposed substance (C) (R C ) can be 9 or less, preferably 8 or less.

[0635] When the mass ratio of fluorine atoms in the decomposed substance (C) is 50 mass% or more, the value of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the decomposed substance (C) (R C ) can be 6 or less, preferably 5 or less.

[0636] The mass ratio (mass%) of fluorine atoms in a substance is the mass ratio of fluorine atoms (atomic weight: 19.00) in the molecular weight of the substance. For example, the mass ratio of fluorine atoms in tetrafluoroethylene (molecular weight 100.02, CF2=CF2) is 75.98% (75.98 = ((19.00 x 4) / 100.02) x 100).

[0637] The production method of the present application is suitable as a production method of the compositions (1) and (2) described later.

[0638] Composition (1)

[0639] One embodiment of the present application is a composition containing a fluorine-containing polymer (A) and a compound (BC) selected from at least one of a polymerization initiator (B) and a decomposed substance (C) of the polymerization initiator (B) (hereinafter sometimes referred to as composition (1)). Since the content of the compound (BC) in the composition (1) is small, the composition (1) can be effectively used as a supply source of the fluorine-containing polymer (A) having high ultraviolet transparency (for example, a supply source of the fluorine-containing polymer (A) used for an ultraviolet-transmitting article (preferably, a lens of an ultraviolet light-emitting element)).

[0640] The fluorine-containing polymer (A) is preferably produced by the production method of the fluorine-containing polymer (A) of the present application, because the content of the polymerization initiator and / or its decomposition product is reduced. In addition, the fluorine-containing polymer (A) can also be produced by a publicly known production method, and can also be a product refined to reduce the content of the polymerization initiator and / or its decomposition product. It can be synthesized by a publicly known production method, for example, by polymerizing a monomer corresponding to the structural unit of the fluorine-containing polymer (A). As the polymerization method, radical polymerization, bulk polymerization, precipitation polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and the like can be used. As the publicly known production method, precipitation polymerization is preferred from the viewpoint of high transmittance of the fluorine-containing polymer (A).

[0641] In the composition (1), the content of the fluorine-containing polymer (A) can be 95% by mass or more with respect to the mass of the composition (1). It is preferably 97 to 100% by mass, more preferably 98 to 100% by mass, and particularly preferably 99 to 100% by mass.

[0642] In the composition (1), the content of the compound (BC) can be 0.1 to 100 ppm by mass, preferably 0.1 to 90 ppm by mass, more preferably 0.1 to 80 ppm by mass, and particularly preferably 0.1 to 70 ppm by mass, with respect to the mass of the composition (1).

[0643] The composition (1) can contain other components in addition to the fluorine-containing polymer (A) and the compound (BC), but is preferably free of them. As the other components, metals such as Fe and Ni, residual solvents, and the like can be exemplified. In the composition (1), the content of the other components can be 0 to 0.1% by mass, 0 to 0.01% by mass.

[0644] The composition (1) can be produced by the production method of the present application. For example, the solid material obtained by the filtration step, or the washed material obtained by washing it with a solvent can be the composition (1). In addition, the composition (1) can also be produced by mixing the fluorine-containing polymer (A) and the compound (BC).

[0645] The average transmittance of the composition (1) at 240 to 340 nm can be 85% or more, 86% or more, 87% or more, 85 to 95%, or 86 to 95%. The average transmittance is preferably high. In the present specification, the average transmittance is determined as described below.

[0646] Average transmittance

[0647] The average transmittance of a sample at a specific wavelength (for example, 240 to 340 nm) is measured using a Hitachi spectrophotometer U-4100. The sample is a flat plate having an average thickness of 1 mm. As the detector, an integrating sphere detector is used.

[0648] Lens for ultraviolet light emitting element

[0649] One embodiment of the present application is a lens for ultraviolet light emitting element containing a fluorine-containing polymer (A) which contains a structural unit represented by formula (A) as a main component and has an average transmittance of 85% or more at a wavelength of 240 nm to 340 nm.

[0650]

[0651] [In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group.]

[0652] The fluorine-containing polymer (A) has an average transmittance of 85% or more at a wavelength of 240 nm to 340 nm. Such a fluorine-containing polymer (A) is suitably manufactured by the manufacturing method of the present application. According to the manufacturing method of the present application, the content of the compound (BC) in the manufactured fluorine-containing polymer (A) is very small. Therefore, it is inferred that the average transmittance of the fluorine-containing polymer (A) at a wavelength of 240 nm to 340 nm is increased.

[0653] The average transmittance of the fluorine-containing polymer (A) at a wavelength of 240 nm to 340 nm can be 85% or more, 86% or more, 87% or more, 85 to 95%, 86 to 95%.

[0654] The lens for ultraviolet light emitting element is desired to have high ultraviolet transmittance, not to be easily scratched, and not to be easily broken. The lens for ultraviolet light emitting element of the present application is not easily scratched because the surface hardness of the raw material resin (fluorine-containing polymer (A)) is high. The lens for ultraviolet light emitting element of the present application is not easily broken because the toughness of the raw material resin is high. Therefore, even if the raw material resin is molded into a lens having a fine structure, the fine structure is not easily broken or damaged. For example, the lens for ultraviolet light emitting element of the present application is suitably used as a lens having a fine structure such as a Fresnel lens.

[0655] The lens for ultraviolet light emitting element is, for example, a Fresnel lens, a microlens, a curved lens, a non-curved lens, a lenticular lens, a plano-convex lens, a convex meniscus lens, a lenticular lens, a plano-concave lens, a concave meniscus lens, a cylindrical lens, a toric lens, a parabolic lens, a special-shaped lens, a diffractive lens, and an array lens thereof, and is preferably a Fresnel lens, a microlens, a lenticular lens, a plano-convex lens, a lenticular lens, a plano-concave lens, a special-shaped lens, a diffractive lens, or an array lens thereof.

[0656] The lens for ultraviolet light emitting element can be manufactured by molding the fluorine-containing polymer (A) using a publicly known lens molding method. The molding conditions can be appropriately adjusted from the publicly known conditions as needed. For example, the lens for ultraviolet light emitting element is manufactured by being formed into a desired shape by injection molding or the like in which the fluorine-containing polymer (A) is melted and then injected. The fluorine-containing polymer (A) can also be molded into a desired shape by other methods, such as press molding in which a fluorine-containing polymer (A) processed into a flat plate is pressed against a heated mold, or the like.

[0657] The ultraviolet light emitting element to which the lens for ultraviolet light emitting element is applied is preferably an ultraviolet light emitting diode (LED). The ultraviolet light emitting element is an element that mainly emits ultraviolet light, such as light having a wavelength of 100 to 400 nm (preferably 240 to 340 nm, more preferably 250 to 270 nm). As the wavelength, there are UV-A, UV-B, UV-C, and the like, which are industrially valuable, and the lens for ultraviolet light emitting element can be applied to any kind of ultraviolet light emitting element, but is preferably applied to a UV-C light emitting element.

[0658] In the present specification, the "lens" does not include a so-called "package" for a light emitting element.

[0659] Composition (2)

[0660] One embodiment of the present application is a composition (hereinafter sometimes referred to as composition (2)) containing a fluorine-containing polymer (Al) that is generated in the form of a precipitate by polymerizing a fluorine-containing monomer (Ml) in the presence of the fluorine-containing monomer (Ml) represented by formula (Ml), a polymerization initiator (B), and a solvent (D).

[0661]

[0662] The fluorine-containing polymer (Al) contains a structural unit represented by formula (Al) as a main component.

[0663]

[0664] In the composition (2), the fluorine-containing monomer (Ml) contains at least one compound selected from the group consisting of a compound represented by formula (Nl) and a compound represented by formula (N2). The content is 0.0001 to 10% by mass, and can be 0.0001 to 8% by mass, 0.0001 to 6% by mass, with respect to the mass of the raw material monomer. The compound (Nl) and the compound (N2) can be one alone or two or more in combination.

[0665]

[0666]

[0667] In the composition (2), the value (R A1 ) of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the fluorine-containing polymer (Al) can be 4 or more.

[0668] In the composition (2), when the mass ratio of the fluorine atom in the polymerization initiator (B) is less than 50 mass%, the value (R B ) of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the polymerization initiator (B) can be 9 or less, preferably 8 or less.

[0669] In the composition (2), when the mass ratio of the fluorine atom in the polymerization initiator (B) is 50 mass% or more, the value (R B ) of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the polymerization initiator (B) can be 6 or less, preferably 5 or less.

[0670] In the composition (2), when the mass ratio of the fluorine atom in the decomposed matter (C) is less than 50 mass%, the value (R C ) of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the decomposed matter (C) can be 9 or less, preferably 8 or less.

[0671] In the composition (2), when the mass ratio of the fluorine atom in the decomposed matter (C) is 50 mass% or more, the value (R C ) of the solubility index R calculated based on the HSP of the solvent (D) and the HSP of the decomposed matter (C) can be 6 or less, preferably 5 or less.

[0672] Since the content of the compound (BC) in the composition (2) is small, the composition (2) can be effectively used as a supply source of the fluorine-containing polymer (Al) having high ultraviolet transparency (for example, a supply source of the fluorine-containing polymer (A) used for an ultraviolet-transmitting article (preferably, a lens of an ultraviolet light emitting element)).

[0673] The fluorine-containing polymer (Al) is preferably produced by the production method of the fluorine-containing polymer (A) of the present application, because the content of the polymerization initiator and / or its decomposition product is reduced. In addition, the fluorine-containing polymer (Al) can also be produced by a publicly known production method, and can also be a product refined to reduce the content of the polymerization initiator and / or its decomposition product. It can be synthesized by a publicly known production method, for example, by polymerizing a monomer corresponding to the structural unit of the fluorine-containing polymer (Al). As the polymerization method, radical polymerization, bulk polymerization, precipitation polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and the like can be used. As the publicly known production method, precipitation polymerization is preferred from the viewpoint of high transmittance of the fluorine-containing polymer (Al).

[0674] In the composition (2), the content of the fluorine-containing polymer (Al) can be 95% by mass or more with respect to the mass of the composition (2). It is preferably 97 to 100% by mass, more preferably 98 to 100% by mass, and particularly preferably 99 to 100% by mass.

[0675] Details of the polymerization in the composition (2) are described using the details described in the polymerization step described above.

[0676] The composition (2) can contain other components in addition to the fluorine-containing polymer (A), but is preferably free of them. As the other components, metals such as Fe and Ni, residual solvents, and the like can be exemplified. In the composition (2), the content of the other components can be 0 to 0.1% by mass, 0 to 0.01% by mass.

[0677] The composition (2) can be produced by the production method of the present application. For example, the solid material obtained by the filtration step, or the washed material obtained by washing it with a solvent can be the composition (2).

[0678] The embodiments have been described above, but it should be understood that the modes and details can be changed in various ways without departing from the gist and scope of the claimed invention.

[0679] Examples

[0680] One embodiment of the present application is described in more detail below using examples, but the present application is not limited thereto.

[0681] The meanings of the symbols and abbreviations in the examples are as follows.

[0682] PFMMD: fluorine-containing monomer (M1)

[0683] HF adduct: compound (N1)

[0684] NPP: di-n-propyl peroxydicarbonate 50% methanol solution (manufactured by NOF Corporation)

[0685] DHP: Bis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-l-oxoheptyl) peroxide 8% fluorine-based solvent dilution (manufactured by NOF Corporation)

[0686] TBPOA: t-Butyl peroxyacetate 50% hydrocarbon-based solvent dilution (manufactured by NOF Corporation)

[0687] HFE-356mec: 1,1,2,3,3,3-hexafluoropropyl methyl ether

[0688] n=2 Alcohol: 2,2,3,3,4,4,5,5-octafluoro-l-pentanol (manufactured by Daikin Industries, Ltd.)

[0689] FC-3283: Perfluoro-n-propylamine (manufactured by 3M Company)

[0690] The polymerization initiators and their decomposition products are as follows. In the present example, the decomposition product of NPP is a -COOH body, the decomposition product of DHP is a -COOH body and a -COF body, and the decomposition product of TBPOA is a -COOH body.

[0691]

[0692] The Hansen solubility parameters are as follows.

[0693] [Table 1]

[0694]

[0695] Average transmittance

[0696] The average transmittance of the sample at a specific wavelength (e.g., 240 nm to 340 nm) was measured using a Hitachi spectrophotometer U-4100. The sample was prepared as a flat plate having an average thickness of 1 mm. As the detector, an integrating sphere detector was used.

[0697] Example 1

[0698] A SUS-made autoclave having a capacity of 300 mL was charged with a fluorine-containing monomer (Ml) containing 3.6% of the compound (Nl) (100 g), HFE-356mec (400 g, solvent), followed by DHP (0.1 g, polymerization initiator). After cooling the autoclave to -78°C, the atmosphere in the system was replaced with nitrogen, and the internal pressure was filled with nitrogen to 0.1 MPaG. The polymerization was carried out at 15°C for 24 hours, and a polymer-solvent mixture in which the resulting fluorine-containing polymer (Al) was precipitated in the solvent was obtained. The mixture was separated by filtration, and dried at 120°C to obtain a solid polymer. The polymer corresponds to Composition (1), and also to Composition (2).

[0699] The polymer 1 g was dissolved in hexafluorobenzene 10 g, and the compound (BC) in the polymer was quantified by gas chromatography, and the result was 20 ppm.

[0700] The polymer was melt-formed to produce a flat plate having an average thickness of 1 mm. The average transmittance (240 nm to 340 nm) of the flat plate was 90%.

[0701] A flat plate having an average thickness of 1 mm obtained by the same method was used as a material, and a Fresnel lens was produced by cutting processing. The surface roughness of the Fresnel lens was observed by a laser microscope VKX-1000 manufactured by KEYENCE Corporation, and the result was that the surface roughness Sa was 74 nm and Sq was 118 nm.

[0702] Example 2

[0703] The same operation as in Example 1 was performed except that NPP was used instead of DHP and the polymerization temperature was changed to 40°C. The compound (BC) in the obtained polymer was 43 ppm, and the average transmittance (240 nm to 340 nm) of the flat plate was 87%.

[0704] Example 3

[0705] The same operation as in Example 1 was performed except that n=2 Alcohol was used instead of HFE-356mec. The compound (BC) in the obtained polymer was 17 ppm, and the average transmittance (240 nm to 340 nm) of the flat plate was 92%.

[0706] Example 4

[0707] The same operation as in Example 1 was performed except that n=2 Alcohol was used instead of HFE-356mec, TBPOA was used instead of DHP, and the polymerization temperature was changed to 100°C. The compound (BC) in the obtained polymer was 23 ppm, and the average transmittance (240 nm to 340 nm) of the flat plate was 90%.

[0708] Comparative Example 1

[0709] The same operation as in Example 1 was performed except that CF3CH2OH was used instead of HFE-356mec. The compound (BC) in the obtained polymer was 163 ppm, and the average transmittance (240 nm to 340 nm) of the flat plate was 81%.

[0710] Comparative Example 2

[0711] The same operation as in Example 1 was conducted except that CHCl3was used instead of HFE-356mec. The compound (BC) in the obtained polymer was 124 ppm, and the average transmittance of the flat plate (240 nm to 340 nm) was 80%.

[0712] Comparative Example 3

[0713] The same operation as in Example 1 was conducted except that CHCl3was used instead of HFE-356mec. The compound (BC) in the obtained polymer was 124 ppm, and the average transmittance of the flat plate (240 nm to 340 nm) was 80%.

[0714] Comparative Example 4

[0715] The same operation as in Example 1 was conducted except that the fluorine-containing monomer (Ml) containing 17% of the compound (Nl) was used instead of the fluorine-containing monomer (Ml) containing 3.6% of the compound (Nl), n = 2 Alcohol was used instead of HFE-356mec, TBPOA was used instead of DHP, and the polymerization temperature was changed to 100°C. The compound (BC) in the obtained polymer was 118 ppm, and the average transmittance of the flat plate (240 nm to 340 nm) was 83%.

[0716] Comparative Example 5

[0717] The same operation as in Example 1 was conducted except that FC-3283 was used instead of HFE-356mec. The mixture after polymerization was a solution in which the generated polymer (Al) was dissolved in the solvent.

[0718] The conditions, solubility index, measurement results, etc. of the Examples and Comparative Examples are summarized in Table 2 below.

[0719] [Table 2]

[0720]

Claims

1. A composition characterized by: containing a fluorine-containing polymer (A) and a compound (BC) which is at least one selected from a polymerization initiator (B) and a decomposition product (C) of the polymerization initiator (B), containing 0.1 to 100 mass ppm of the compound (BC) relative to the mass of the composition, the fluorine-containing polymer (A) contains a structural unit represented by formula (A) as a main component, wherein R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group.

2. The composition according to claim 1, characterized in that: the polymerization initiator (B) is a peroxide.

3. The composition according to claim 1, characterized in that: the polymerization initiator (B) is at least one compound selected from a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3), in formula (Bl), R 11 , R 12 , R 13 and R 14 each independently represent a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3- to 20- carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 13 and R 14 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3- to 20- carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, in formula (B2), R 15 and R 16 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, in formula (B3), R 17 and R 18 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

4. The composition according to any one of claims 1 to 3, characterized in that: the decomposition product (C) is at least one compound selected from a compound represented by formula (Cl), a compound represented by formula (C2) and a compound represented by formula (C3), in formula (Cl), R 41 and R 42 each independently represents a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, the alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 43 represents a fluorine atom or a hydroxyl group, in formula (C2), R 45 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group, in formula (C3), R 47 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 represents a fluorine atom or a hydroxyl group.

5. The composition according to any one of claims 1 to 4, characterized in that: the average transmittance at a wavelength of 240 nm to 340 nm is 85% or more.

6. The composition according to any one of claims 1 to 5, characterized in that: the structural unit represented by formula (A) is a structural unit represented by formula (Al), 。 7. The composition according to any one of claims 1, 4 to 6, characterized in that: the polymerization initiator (B) is at least one compound selected from a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3), in formula (Bl), R 11 and R 13 is a fluorine atom, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, and n4 represents an integer of 0 to 5, in formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

8. The composition according to any one of claims 1 to 3 and 5 to 7, characterized in that: the decomposition product (C) is at least one compound selected from a compound represented by formula (Cl), a compound represented by formula (C2) and a compound represented by formula (C3), In formula (C1), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

9. The composition according to claim 1 or 5, characterized in that: the structural unit represented by formula (A) is a structural unit represented by formula (Al), the polymerization initiator (B) is at least one compound selected from a compound represented by formula (Bl), a compound represented by formula (B2) and a compound represented by formula (B3), In formula (B1), R 11 and R 13 are fluorine atoms, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, In formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group, the decomposition product (C) is at least one compound selected from a compound represented by formula (Cl), a compound represented by formula (C2) and a compound represented by formula (C3), In formula (C1), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

10. A method for producing a fluorine-containing polymer (A), characterized by: having a polymerization step of polymerizing a fluorine-containing monomer (M) in the presence of the fluorine-containing monomer (M), a polymerization initiator (B) and a solvent (D) to produce the fluorine-containing polymer (A) in the form of a precipitate. In formula (M), R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group, The fluorine-containing polymer (A) contains a structural unit represented by formula (A) as a main component, In formula (A), R 1 ~R 4 As above, the value of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the fluorine-containing polymer (A) (R A ) is 4 or more, a value (R) of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the polymerization initiator (B) B ) is 9 or less when the mass ratio of fluorine atoms in the polymerization initiator (B) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or more, a value (R) of a solubility index R calculated based on a Hansen solubility parameter of the solvent (D) and a Hansen solubility parameter of a decomposition product (C) of the polymerization initiator (B) C ) is 9 or less when the mass ratio of fluorine atoms in the decomposition product (C) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or more, The solubility index R is calculated by the following formula, R = {4 x (δD1 - δD2) 2 + (δP1 - δP2) 2 + (δH1 - δH2) 2} / 3 0.5 In the formula, δD1, δP1, and δH1 represent the dispersion term, the polarity term, and the hydrogen bonding term, respectively, of the Hansen solubility parameter of element 1, and δD2, δP2, and δH2 represent the dispersion term, the polarity term, and the hydrogen bonding term, respectively, of the Hansen solubility parameter of element 2.

11. The method for producing the fluorine-containing polymer (A) according to claim 10, wherein: Further having a filtration process of filtering the precipitate and the polymerization product liquid generated in the polymerization process, thereby removing the polymerization product liquid to obtain the fluorine-containing polymer (A).

12. The method for producing the fluorine-containing polymer (A) according to claim 10 or 11, wherein: The polymerization initiator (B) is a peroxide compound.

13. The method for producing the fluorine-containing polymer (A) according to claim 10 or 11, wherein: The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 , R 12 , R 13 and R 14 each independently represent a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, The alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 13 and R 14 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, In formula (B2), R 15 and R 16 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, In formula (B3), R 17 and R 18 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

14. The method for producing the fluorine-containing polymer (A) according to any one of claims 10 to 13, wherein: The decomposition product (C) of the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (C1), R 41 and R 42 each independently represents a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, The alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the alkyl and fluoroalkyl groups can each have an etheric oxygen atom, R 49 represents a fluorine atom or a hydroxyl group.

15. The method for producing the fluorine-containing polymer (A) according to any one of claims 10 to 14, wherein: The fluorine-containing monomer (M) is a compound represented by formula (M1), The structural unit represented by formula (A) is a structural unit represented by formula (A1), 。 16. The method for producing the fluorine-containing polymer (A) according to any one of claims 10 to 15, wherein: The fluorine-containing monomer (M) contains 0.0001 to 10 mass% of a compound (N) with respect to the mass of the raw material monomer, The compound (N) is a compound represented by formula (N), In the formula, R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group, R 71 and R 72 each independently represents a hydrogen atom or a fluorine atom, in the case where either of R 71 and R 72 is a hydrogen atom, the group of the other represents a fluorine atom.

17. The method for producing the fluorine-containing polymer (A) according to claim 16, wherein: The compound (N) is at least one compound selected from the group consisting of a compound represented by formula (N1) and a compound represented by formula (N2), 。 18. The method for producing the fluorine-containing polymer (A) according to any one of claims 10, 11, and 14 to 17, wherein: The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 and R 13 is a fluorine atom, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, and n4 represents an integer of 0 to 5, In formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

19. The method for producing the fluorine-containing polymer (A) according to any one of claims 10 to 13 and 15 to 18, wherein: The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (C1), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

20. The method for producing a fluorine-containing polymer (A) according to any one of claims 10 to 19, characterized in that: The solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

21. The method for producing a fluorine-containing polymer (A) according to claim 10 or 11, characterized in that: The fluorine-containing monomer (M) is a compound represented by formula (M1), The fluorine-containing monomer (M) contains 0.0001 to 10 mass% of a compound (N) with respect to the mass of the raw material monomer, The compound (N) is at least one compound selected from the group consisting of a compound represented by formula (N1) and a compound represented by formula (N2), The structural unit represented by formula (A) is a structural unit represented by formula (A1), The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 and R 13 is a fluorine atom, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, In formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group, The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (C1), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (C1), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group, The solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

22. A lens for an ultraviolet light emitting element, characterized by: containing a fluorine-containing polymer (A), The fluorine-containing polymer (A) contains a structural unit represented by formula (A) as a main component, wherein R 1 ~R 4 each independently represents a fluorine atom, a C1-C5 perfluoroalkyl group or a C1-C5 perfluoroalkoxy group, The average transmittance of the fluorine-containing polymer (A) at a wavelength of 240 nm to 340 nm is 85% or more.

23. The lens for an ultraviolet light emitting element according to claim 22, characterized in that: The structural unit represented by formula (A) is a structural unit represented by formula (A1), 。 24. A composition containing a fluorine-containing polymer (A1), characterized by: The fluorine-containing polymer (A1) is generated in the form of a precipitate by polymerizing a fluorine-containing monomer (M1) in the presence of the fluorine-containing monomer (M1) represented by formula (M1), a polymerization initiator (B), and a solvent (D), The fluorine-containing polymer (A1) contains a structural unit represented by formula (A1) as a main component, The fluorine-containing monomer (M1) contains 0.0001 to 10 mass% of at least one compound selected from the group consisting of a compound represented by formula (N1) and a compound represented by formula (N2) with respect to the mass of the raw material monomer, the value of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the fluorine-containing polymer (Al) (R A1 ) is 4 or more, a value (R) of a solubility index R calculated based on the Hansen solubility parameter of the solvent (D) and the Hansen solubility parameter of the polymerization initiator (B) B ) is 9 or less when the mass ratio of fluorine atoms in the polymerization initiator (B) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or more, a value (R) of a solubility index R calculated based on a Hansen solubility parameter of the solvent (D) and a Hansen solubility parameter of a decomposition product (C) of the polymerization initiator (B) C ) is 9 or less when the mass ratio of fluorine atoms in the decomposition product (C) is less than 50 mass%, and is 6 or less when the mass ratio is 50 mass% or more, The solubility index R is calculated from the following formula: R = {4 x (δD1 - δD2) 2 + (δP1 - δP2) 2 + (δH1 - δH2) 2} 0.5 In the formula, δD1, δP1, and δH1 represent a dispersion term, a polarity term, and a hydrogen bond term, respectively, of the Hansen solubility parameter of element 1, and δD2, δP2, and δH2 represent a dispersion term, a polarity term, and a hydrogen bond term, respectively, of the Hansen solubility parameter of element 2.

25. The composition containing a fluorine-containing polymer (A1) according to claim 24, characterized in that: The polymerization initiator (B) is a peroxide.

26. The composition containing a fluorine-containing polymer (A1) according to claim 24, characterized in that: The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 , R 12 , R 13 and R 14 each independently represent a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, The alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 11 and R 12 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 13 and R 14 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3- to 20- carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, In formula (B2), R 15 and R 16 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, In formula (B3), R 17 and R 18 each independently represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, and the alkyl and fluoroalkyl groups can each have an etheric oxygen atom.

27. The composition containing the fluorine-containing polymer (Al) according to claim 24 or 25, wherein: The decomposition product (C) of the polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (Cl), R 41 and R 42 each independently represents a fluorine atom, a C1-C20 alkyl group or a C1-C20 fluoroalkyl group, The alkyl group and the fluoroalkyl group can each have an etheric oxygen atom, R 41 and R 42 may be linked to each other to form a 4- to 20-membered ring having at least one fluorine atom as a ring-constituting atom, or a 4- to 22-membered ring having at least one fluorine atom as a ring-constituting atom, with 3 to 20 carbon atoms and 1 or 2 oxygen atoms or 1 sulfur atom as ring-constituting atoms, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a C1-C20 linear or branched alkyl group, a C1-C20 linear or branched fluoroalkyl group, a C4-C8 cyclic alkyl group, a C4-C8 cyclic fluoroalkyl group, or a C4-C14 aryl group which can have a fluorine atom, the alkyl and fluoroalkyl groups each can have an etheric oxygen atom, R 49 represents a fluorine atom or a hydroxyl group.

28. The composition containing the fluorine-containing polymer (Al) according to claim 24, wherein: The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 and R 13 is a fluorine atom, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, -O- (CF2) n3 CF3or -O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, and n4 represents an integer of 0 to 5, In formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group.

29. The composition containing the fluorine-containing polymer (Al) according to any one of claims 24 to 26 and 28, wherein: The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (C1), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group.

30. The composition containing the fluorine-containing polymer (Al) according to any one of claims 24 to 29, wherein: The solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

31. The composition containing the fluorine-containing polymer (Al) according to claim 24, wherein: The polymerization initiator (B) is at least one compound selected from the group consisting of a compound represented by formula (B1), a compound represented by formula (B2), and a compound represented by formula (B3), In formula (B1), R 11 and R 13 is a fluorine atom, R 12 and R 14 each independently represents - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, and n4 represents an integer of 0 to 5, In formula (B2), R 15 and R 16 each independently represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, In formula (B3), R 17 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 18 represents a t-butyl group, a t-hexyl group, or a trifluoromethyl group, The decomposition product (C) is at least one compound selected from the group consisting of a compound represented by formula (Cl), a compound represented by formula (C2), and a compound represented by formula (C3), In formula (Cl), R 41 represents a fluorine atom, R 42 CF3, - (CF2) n1 CF3, - (CF2) n2 CF2H, - O- (CF2) n3 CF3or - O- (CF2) n4 CF2H, wherein n1 represents an integer of 0 to 5, n2 represents an integer of 0 to 5, n3 represents an integer of 0 to 5, n4 represents an integer of 0 to 5, R 43 represents a fluorine atom or a hydroxyl group, In formula (C2), R 45 represents a C1-C7 linear or branched alkyl group, or a C1-C7 linear or branched fluoroalkyl group, R 46 represents a fluorine atom or a hydroxyl group, In formula (C3), R 47 represents a methyl group, a t-butyl group, a t-nonyl group, a trifluoromethyl group, a perfluoroisopentyl group, or a phenyl group, R 49 represents a fluorine atom or a hydroxyl group, The solvent (D) is at least one selected from the group consisting of a hydrofluoroether and a fluoroalcohol.

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