Process for the production of fluoropolymers and compositions

Abstract

This invention provides a method for manufacturing a fluoropolymer with minimal deviation in weight-average molecular weight per batch. The method for manufacturing the fluoropolymer of this invention is characterized by comprising the following steps: a fluoropolymer synthesis step, wherein a diol represented by formula (3) is reacted with at least one selected from unsaturated carboxylic acids, esters of the unsaturated carboxylic acids, acyl halides of the unsaturated carboxylic acids, and anhydrides of the unsaturated carboxylic acids to obtain a composition comprising a fluoropolymer represented by formula (4) as the main reactant and a fluoropolymer represented by formula (5) as a by-reactant; a fluoropolymer purification step, wherein the fluoropolymer represented by formula (5) is removed from the composition, and the content of the fluoropolymer represented by formula (5) is 1500 ppm or less, expressed as a mass fraction (parts per million) based on the fluoropolymer represented by formula (4); and a polymerization step, wherein the composition after the fluoropolymer purification step is subjected to a polymerization reaction to produce a fluoropolymer comprising a repeating unit represented by formula (1) and a repeating unit represented by formula (2). In equations (1), (2), (3), (4), and (5), R 1 R 2 Each of the following is independently a hydrogen atom, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl, R 3 R 4 Each is independently a hydrogen atom, methyl or ethyl, R 5 R is a hydrogen atom or a trifluoromethyl group. 6 It can be a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing a fluorine-containing polymer and a composition. BACKGROUND

[0002] Fluorine-containing polymers (fluorine-containing compounds) have been used or developed in a wide range of application fields centered on the field of advanced materials due to the characteristics of fluorine such as hydrophobicity, oleophobicity, low water absorption, heat resistance, weather resistance, corrosion resistance, transparency, photosensitivity, low refractive index, low dielectricity, and the like. In particular, with respect to coating applications, active research and development have been conducted in the fields of antireflection films that utilize low refractive index and the transmission of visible light, optical devices that utilize the transmission of a high wavelength band (optical communication wavelength band), resist materials that utilize the transmission of the ultraviolet region (particularly, the vacuum ultraviolet wavelength region), and the like. As a general polymer design in these application fields, the transmission at each wavelength of use is achieved by introducing as many fluorines as possible, and adhesion to a substrate, a high glass transition point (hardness) are achieved.

[0003] As a monomer constituting such a fluorine-containing polymer, a polymerizable monomer represented by the following formula (6) is described in Patent Literature 1.

[0004] [Chemical Formula 1]

[0005]

[0006] (In formula (6), R 1p represents a group selected from a hydrogen atom, a halogen atom, a hydrocarbon group, and a fluorine-containing alkyl group (the fluorine-containing alkyl group is linear or branched, and can include a cyclic structure). R 2p is a divalent to trivalent organic group, which is a group selected from an aliphatic hydrocarbon group (the aliphatic hydrocarbon group is linear or branched, and can include a cyclic structure), an aromatic ring group, or a complex substituent of these, and a part or all of the hydrogen atoms thereof can be substituted with a fluorine atom or a hydroxyl group. R 3p is a hydrogen atom, a hydrocarbon group, a fluorine-containing alkyl group (the fluorine-containing alkyl group is linear or branched, and can include a cyclic structure), or an aromatic ring group, and a divalent linking group selected from an ether group (-O-), a carbonyl group (-(C=O)-) can be included in the interior of the hydrocarbon group or the fluorine-containing alkyl group. m represents an integer of 1 to 2. When m is 2, two R 3p may be the same group, or can be different groups.

[0007] The polymerizable monomer represented by formula (6) is a monomer compound having a (CF3)2(OR 3p )C- site from hexafluoroacetone, has a high fluorine content, and successfully has a polar group in the same molecule in a well-balanced manner.

[0008] It is known that the polymerizability of this polymerizable monomer is also excellent, and a fluorine-containing polymer obtained by polymerizing this polymerizable monomer has both the permeability due to the fluorine atom and the adhesion and processability due to the polar group, and has excellent physical properties as an antireflection film material, an optical device material, a material for a resist, and the like.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent No. 4083399 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] In the production of a fluorine-containing polymer using a polymerizable monomer represented by formula (6), in the case where R 3p In the case where R of formula (6) is hydrogen, that is, in the case where the polymerizable monomer represented by formula (6) has a hydroxyl group, there is a phenomenon that the weight average molecular weight of the fluorine-containing polymer produced in each batch is deviated.

[0014] If the weight average molecular weight of the fluorine-containing polymer in each batch is deviated, in the formation of a resist pattern using the fluorine-containing polymer, the alkali solubility is changed, and in each batch thereof, it is sometimes necessary to adjust the exposure and development conditions in the formation of a resist pattern, and sometimes the production efficiency of a semiconductor is affected.

[0015] The present application has an object to provide a production method of a fluorine-containing polymer in which the deviation of the weight average molecular weight in each batch is small.

[0016] SOLUTION TO THE PROBLEM

[0017] The present inventors have made intensive studies in view of the above-described problems. As a result, it has been found that a by-product produced in the production of a polymerizable monomer is the cause of the deviation of the weight average molecular weight of the fluorine-containing polymer in each batch, and thus the present application has been completed.

[0018] That is, the present application is as described below.

[0019] The manufacturing method of the fluorine-containing polymer according to the present application is characterized by being a method of manufacturing a fluorine-containing polymer containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), comprising: a fluorine-containing monomer synthesis step of reacting a diol represented by the following formula (3) with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the unsaturated carboxylic acid, a halide of the unsaturated carboxylic acid, and an anhydride of the unsaturated carboxylic acid to obtain a composition containing a fluorine-containing monomer represented by the following formula (4) as a main reaction product and a fluorine-containing monomer represented by the following formula (5) as a side reaction product; a fluorine-containing monomer purification step of removing the fluorine-containing monomer represented by the formula (5) from the composition, the content of the fluorine-containing monomer represented by the formula (5) being 1500 ppm or less in terms of mass per million of the fluorine-containing monomer represented by the formula (4); and a polymerization step of performing a polymerization reaction using the composition after the fluorine-containing monomer purification step to produce the fluorine-containing polymer containing the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2).

[0020] [Chemical Formula 2]

[0021]

[0022] (In the formula (1), the formula (2), the formula (3), the formula (4), and the formula (5), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group, or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, and R 6 is a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.)

[0023] In the manufacturing method of the fluorine-containing polymer according to the present application, it is preferable that, in the polymerization step, the fluorine-containing polymer is synthesized in such a manner that the relative standard deviation, which is a value obtained by dividing the standard deviation of the weight average molecular weight of the obtained fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer, is 0.10 to 1.10.

[0024] In the manufacturing method of the fluorine-containing polymer according to the present application, it is preferable that R 5 is a trifluoromethyl group.

[0025] In the manufacturing method of the fluorine-containing polymer according to the present application, it is preferable that R 3 and R 4 are hydrogen atoms.

[0026] In the manufacturing method of the fluorine-containing polymer according to the present application, it is preferable that R 1 is a methyl group or an i-propyl group, and R 2 is a hydrogen atom.

[0027] In the production method of the fluorine-containing polymer of the present application, it is preferable that the polymerization reaction in the above polymerization step is performed using the above composition containing other monomers than the fluorine-containing monomer represented by the above formula (4) and the fluorine-containing monomer represented by the above formula (5).

[0028] In the production method of the fluorine-containing polymer of the present application, it is preferable that the polymerization reaction in the above polymerization step is a radical polymerization reaction.

[0029] In the production method of the fluorine-containing polymer of the present application, it is preferable that the above radical polymerization reaction is performed in an organic solvent.

[0030] The composition of the present application is characterized by containing the fluorine-containing monomer represented by the above formula (4) and the fluorine-containing monomer represented by the above formula (5), and the mass parts per million based on the fluorine-containing monomer represented by the above formula (4) of the fluorine-containing monomer represented by the above formula (5) is 1500 ppm or less.

[0031] [Chemical Formula 3]

[0032]

[0033] (In formula (4) and formula (5), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, and R 6 is a hydrogen atom, a chlorine atom, a methyl group or a trifluoromethyl group.)

[0034] In the composition of the present application, it is preferable that R 5 is a trifluoromethyl group.

[0035] In the composition of the present application, it is preferable that R 3 , R 4 is a hydrogen atom.

[0036] In the composition of the present application, it is preferable that R 1 is a methyl group or an isopropyl group, and R 2 is a hydrogen atom.

[0037] The composition of the present application preferably further contains other monomers than the fluorine-containing monomer represented by the above formula (4) and the fluorine-containing monomer represented by the above formula (5).

[0038] The composition of the present application preferably further contains an organic solvent.

[0039] Effects of the Invention

[0040] The present application can provide a method for producing a fluorine-containing polymer having a small variation in weight average molecular weight per batch.

[0041] Further, the content of the fluorine-containing monomer represented by formula (5) in the composition of the present application is small, and thus a fluorine-containing polymer having a small variation in weight average molecular weight per batch can be produced by using the composition of the present application. DETAILED DESCRIPTION

[0042] Hereinafter, the present application will be described in detail, but the description of the constituent elements described below is an example of the embodiments of the present application, and the present application is not limited to these specific contents. Various modifications can be made within the scope of the gist of the present application.

[0043] In the "DETAILED DESCRIPTION" column of the present specification, matters represented by "[ ]" and "]", "<" and ">" are only symbols and have no meaning by themselves.

[0044] The method for producing a fluorine-containing polymer of the present application is a method for producing a fluorine-containing polymer containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), comprising: a fluorine-containing monomer synthesis step, a fluorine-containing monomer purification step, and a polymerization step.

[0045] In the fluorine-containing monomer synthesis step, a diol represented by the following formula (3) is reacted with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the above unsaturated carboxylic acid, an acid halide of the above unsaturated carboxylic acid, and an acid anhydride of the above unsaturated carboxylic acid, to obtain a composition containing a fluorine-containing monomer represented by the following formula (4) as a main reaction product and a fluorine-containing monomer represented by the following formula (5) as a side reaction product.

[0046] In the fluorine-containing monomer purification step, the fluorine-containing monomer represented by formula (5) is removed from the composition obtained in the fluorine-containing monomer synthesis step, and the content of the fluorine-containing monomer represented by formula (5) is made to be 1500 ppm or less, based on the mass of the fluorine-containing monomer represented by formula (4).

[0047] In the polymerization step, a polymerization reaction is performed using the composition after the fluorine-containing monomer purification step, to produce a fluorine-containing polymer containing the repeating unit represented by formula (1) and the repeating unit represented by formula (2).

[0048] [Chemical Formula 4]

[0049]

[0050] (In formula (1), formula (2), formula (3), formula (4), and formula (5), R 1 , R 2each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group, or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, R 6 is a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.

[0051] In the production method of the fluorine-containing polymer of the present application, a fluorine-containing monomer represented by the following formula (4) is generated as a main reactant and a fluorine-containing monomer represented by the following formula (5) is generated as a side reactant in the fluorine-containing monomer synthesis step. The fluorine-containing monomer represented by the formula (5) as a side reactant becomes a cause of the deviation of the weight average molecular weight of each batch of the fluorine-containing polymer obtained through the subsequent steps.

[0052] However, in the production method of the fluorine-containing polymer of the present application, the fluorine-containing monomer represented by the formula (5) as a side reactant is removed from the composition in the fluorine-containing monomer purification step so that the content of the fluorine-containing monomer represented by the formula (5) is 1500 ppm or less in terms of mass parts per million based on the fluorine-containing monomer represented by the formula (4). Therefore, when the fluorine-containing polymer is produced by the production method of the fluorine-containing polymer of the present application, the deviation of the weight average molecular weight of each batch of the fluorine-containing polymer can be reduced.

[0053] Hereinafter, each step in the production method of the fluorine-containing polymer of the present application is explained in detail.

[0054] <Fluorine-containing monomer synthesis step>

[0055] In the production method of the fluorine-containing polymer of the present application, the fluorine-containing monomer synthesis step is performed first.

[0056] In the fluorine-containing monomer synthesis step, a diol represented by the following formula (3) is reacted with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid (hereinafter also referred to as "unsaturated carboxylic acid, etc.).

[0057] Thereby, a composition containing a fluorine-containing monomer represented by the following formula (4) as a main reactant and a fluorine-containing monomer represented by the following formula (5) as a side reactant can be obtained.

[0058] [Chemical Formula 5]

[0059]

[0060] (in the formula (3), the formula (4), and the formula (5), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a t-butyl group, R3 R 4 each independently is a hydrogen atom, a methyl group or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, R 6 is a hydrogen atom, a chlorine atom, a methyl group or a trifluoromethyl group.

[0061] In the reaction in the fluorine-containing monomer synthesis process, the diol represented by formula (3) has both a fluorine atom-containing alcohol site and an alkyl alcohol site not having a fluorine atom in the same molecule. The fluorine atom-containing alcohol site has an electron-withdrawing property and a bulky trifluoromethyl group.

[0062] It is presumed that by the electron-withdrawing property and the steric effect of the fluorine atom-containing alcohol site, the nucleophilicity of the non-covalent electron pair of the alcohol site is suppressed, and the addition reaction of an unsaturated carboxylic acid or the like does not easily occur, and the fluorine-containing monomer represented by formula (4) is synthesized as a main reactant.

[0063] Further, the fluorine atom-containing alcohol site remains in the fluorine-containing monomer represented by formula (4). A small amount of addition reaction of an unsaturated carboxylic acid or the like occurs in this fluorine atom-containing alcohol site. Therefore, in the synthesis of the fluorine-containing monomer represented by formula (4), the fluorine-containing monomer represented by formula (5) is synthesized as an unavoidable by-product.

[0064] As a result, the composition obtained in the fluorine-containing monomer synthesis process contains the fluorine-containing monomer represented by formula (4) as a main reactant and the fluorine-containing monomer represented by formula (5) as a by-product.

[0065] Further, in the fluorine-containing monomer synthesis process, sometimes an unsaturated carboxylic acid or the like is further added to the addition site of an unsaturated carboxylic acid or the like of the fluorine-containing monomer represented by formula (4), and the fluorine-containing monomer represented by formula (7) described below is synthesized.

[0066] The composition obtained in the fluorine-containing monomer synthesis process can contain the fluorine-containing monomer represented by formula (7).

[0067] [Chemical Formula 6]

[0068]

[0069] (In formula (7), R 1 R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group or a t-butyl group, R 3 R 4 each independently is a hydrogen atom, a methyl group or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, R 6 is a hydrogen atom, a chlorine atom, a methyl group or a trifluoromethyl group.

[0070] In addition, as described above, in the diol represented by formula (3), the addition reaction of the unsaturated carboxylic acid or the like does not easily occur at the fluorine-containing alcohol site containing the fluorine atom, and thus a compound in which the addition reaction of the unsaturated carboxylic acid or the like occurs only at the fluorine-containing alcohol site containing the fluorine atom is hardly produced. Furthermore, even if such a compound is produced, the addition reaction of the unsaturated carboxylic acid or the like rapidly occurs at the alkyl alcohol site not having the fluorine atom, which is highly reactive, and the fluorine-containing monomer represented by formula (5) is synthesized.

[0071] Therefore, in the composition obtained in the fluorine-containing monomer synthesis step in the present application, a compound represented by formula (3) in which the addition reaction of the unsaturated carboxylic acid or the like occurs only at the fluorine-containing alcohol site containing the fluorine atom is hardly detected.

[0072] In the diol represented by formula (3), R 1 is preferably a methyl group or an isopropyl group, R 2 is preferably a hydrogen atom, R 4 is preferably a hydrogen atom, R 5 is preferably a trifluoromethyl group.

[0073] As the at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid used in the fluorine-containing monomer synthesis step, a methacrylic acid agent, an acrylic acid agent, and other esterification agents, and the like can be given.

[0074] As the methacrylic acid agent used in the fluorine-containing monomer synthesis step, a methacrylate such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, a methacryl halide such as methacryloyl chloride, methacryloyl fluoride, methacryloyl bromide, methacrylic anhydride, and methacrylic acid can be given.

[0075] As the acrylic acid agent used in the fluorine-containing monomer synthesis step, an acrylate such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, an acryl halide such as acryloyl chloride, acryloyl fluoride, acryloyl bromide, acrylic anhydride, and acrylic acid can be given.

[0076] As the other esterification agent used in the fluorine-containing monomer synthesis step, a carboxylic acid ester, a carboxylic acid halide such as carboxylic acid chloride, a carboxylic acid anhydride, and a carboxylic acid other than those included in the above-described methacrylic acid agent and the above-described acrylic acid agent can be given.

[0077] Among these, a methacrylic acid agent is preferably used, and a methacrylic anhydride and / or a methacryloyl chloride is more preferably used.

[0078] In the fluorine-containing monomer synthesis step, when the diol represented by formula (3) is reacted with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid, an acid or a base can be added as needed.

[0079] In the fluorine-containing monomer synthesis step, as the reaction conditions when the diol represented by formula (3) is reacted with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid, it is preferable to react at 30 to 130°C for 0.5 to 8 hours.

[0080] In the fluorine-containing monomer synthesis step, the amount of generation of the fluorine-containing monomer represented by formula (5) as a by-product varies depending on the kind of the unsaturated carboxylic acid or the like, the reaction temperature, and the reaction time.

[0081] When the amount of use of the unsaturated carboxylic acid or the like is too small, the amount of generation of the fluorine-containing monomer represented by formula (5) can be reduced, but a large amount of the diol represented by formula (3) that has not reacted remains, and thus it is necessary to perform separation of the fluorine-containing monomer represented by formula (4) from the diol represented by formula (3).

[0082] Further, when the amount of use of the unsaturated carboxylic acid is too large, the amount of generation of the fluorine-containing monomer represented by formula (5) increases. Further, sometimes a homopolymer of the unsaturated carboxylic acid or the like is generated.

[0083] For this reason, the molar amount ratio of the diol represented by formula (3) to at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid that is used is preferably [molar amount of the diol represented by formula (3) used] : [molar amount of at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, an acid halide of an unsaturated carboxylic acid, and an acid anhydride of an unsaturated carboxylic acid] = 1 : 0.7 to 1 : 1.3.

[0084] As preferable compounds of the fluorine-containing monomer represented by formula (4) obtained in the fluorine-containing monomer synthesis step, there are mentioned 5,5,5-trifluoro-4-hydroxy-4-trifluoromethylpentan-2-yl methacrylate as a fluorine-containing monomer represented by the following formula (4-1) and 1,1,1-trifluoro-2-hydroxy-2-trifluoromethylheptan-4-yl methacrylate as a fluorine-containing monomer represented by the following formula (4-2).

[0085] [Chemical Formula 7]

[0086]

[0087] <Fluorine-containing monomer purification step>

[0088] Next, in the method for producing a fluorine-containing polymer of the present application, a fluorine-containing monomer purification step is performed.

[0089] In the fluorine-containing monomer purification step, the content of the fluorine-containing monomer represented by formula (5) is made 1500 ppm or less, in terms of mass parts per million based on the fluorine-containing monomer represented by formula (4), from the composition obtained by the fluorine-containing monomer synthesis step.

[0090] Further, the content of the fluorine-containing monomer represented by formula (5) is preferably 450 ppm or less, more preferably 200 ppm or less. Further, the content of the fluorine-containing monomer represented by formula (5) is preferably 10 ppm or more.

[0091] The fluorine-containing monomer represented by formula (5) becomes a cause of variation in the weight average molecular weight of the fluorine-containing polymer of each batch obtained by the subsequent step.

[0092] In the composition after the fluorine-containing monomer synthesis step, the content of the fluorine-containing monomer represented by formula (5) is made 1500 ppm or less, in terms of mass parts per million based on the fluorine-containing monomer represented by formula (4), whereby the variation in the weight average molecular weight of the fluorine-containing polymer of each batch in the fluorine-containing polymer obtained by the subsequent step can be reduced.

[0093] As a method of removing the fluorine-containing monomer represented by formula (5) from the composition, there is no particular limitation, and known methods such as column chromatography, precise distillation, or crystallization, etc. can be used. In order to obtain a fluorine-containing monomer represented by formula (4) having high purity, these methods can be combined.

[0094] Hereinafter, each method is described in detail.

[0095] [Column Chromatography]

[0096] In a general column cylinder base material, a packing agent is filled, and an organic solvent is used as a mobile phase, and the composition is made to flow, whereby the fluorine-containing monomer represented by formula (5) is removed from the composition.

[0097] The packing agent is not particularly limited, and silica gel, alumina gel are preferable, and alumina gel is more preferable. The packing agent can be used singly or two or more kinds can be used.

[0098] The mobile phase is not particularly limited, and general organic solvents such as hexane, heptane, toluene, ethyl acetate, etc. can be used. Further, the mobile phase can be used singly or two or more kinds can be used.

[0099] The temperature at the time of column chromatography is preferably in the range of 0°C to 40°C, and more preferably in the range of 20°C to 30°C.

[0100] If the amount of the filler added (height) is increased, more time is required, but by increasing the amount of the filler added (height), the resolution is improved. As the cylindrical base material for the column, in the case of using Model: ILC-B22-300, Manufacturer: Tsurumaya Mfg. Co., Ltd., the height of the filler is preferably 5 cm to 15 cm.

[0101] [precise distillation]

[0102] The number of theoretical plates of the distillation column required when removing the fluorine-containing monomer represented by formula (5) from the composition using precise distillation is 5 plates or more and 40 plates or less.

[0103] When the number of theoretical plates is less than 5 plates, it is difficult to sufficiently remove the fluorine-containing monomer represented by formula (5). The higher the number of plates of the distillation column, the higher the ability to separate and remove the fluorine-containing monomer represented by formula (5), but if it exceeds 40 plates, the ability to separate and remove approaches the upper limit, and it is not easy to improve the cost performance.

[0104] Furthermore, during the precise distillation, sometimes the fluorine-containing monomer represented by formula (4) undergoes a polymerization reaction. In order to prevent such a polymerization reaction from occurring, a polymerization inhibitor can be added to the composition.

[0105] Furthermore, oxygen can also be introduced into the distillation column.

[0106] As the polymerization inhibitor, there is no particular limitation, and examples that can be given are: o-cresol, m-cresol, p-cresol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-p-cresol, hydroquinone, catechol, 4-tert-butylpyrocatechol, 2,5-bistert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, p-methoxyphenol, 1,2,4-trihydroxybenzene, 1,2-benzoquinone, 1,3-benzoquinone, 1,4-benzoquinone, quinizarin leuco, phenothiazine, 2-methoxyphenothiazine, tetraethylthiuram disulfide, 1,1-diphenyl-2-picrylhydrazine, or 1,1-diphenyl-2-picolylhydrazine.

[0107] As commercially available polymerization inhibitors, examples that can be given are: N,N'-di-2-naphthyl-p-phenylenediamine (trade name, NONFLEX F), N,N-diphenyl-p-phenylenediamine (trade name, NONFLEX H), 4,4'-bis(a,a-dimethylbenzyl)diphenylamine (trade name, NONFLEX DCD), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol) (trade name, NONFLEX MBP), N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine (trade name, OZONE 35), or ammonium N-nitrosophenylhydroxylamine (trade name, Q-1300) or N-nitrosophenylhydroxylamine aluminum salt (trade name, Q-1301) manufactured by Seiko Chemical Co., Ltd.

[0108] The amount of the polymerization inhibitor used in the precise distillation is not particularly limited, and is preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.01 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4) before the precise distillation.

[0109] When the polymerization inhibitor is less than 0.01 parts by mass relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4), it is difficult to prevent the polymerization of the fluorine-containing monomer represented by formula (4).

[0110] When the polymerization inhibitor is more than 5 parts by mass relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4), the effect of preventing the polymerization of the fluorine-containing monomer represented by formula (4) approaches the upper limit, and it is not easy to improve the cost performance.

[0111] In addition, the content of the fluorine-containing monomer represented by formula (4) in the composition can be measured by gas chromatography.

[0112] [Crystallization]

[0113] The fluorine-containing monomer represented by formula (5) can be removed from the composition using crystallization.

[0114] Crystallization is an operation in which the composition is dissolved in a good solvent, and the fluorine-containing monomer represented by formula (4) is precipitated and crystal growth is caused by adding a poor solvent or lowering the temperature.

[0115] As for the kind of the solvent at the time of performing crystallization, there is no particular limitation as long as the fluorine-containing monomer represented by formula (4) is easily soluble or insoluble, and examples include alcohols, nitriles, ketones, amides, sulfoxides, ethers, hydrofluorocarbons, hydrofluoroethers, hydrocarbons, aromatic hydrocarbons, or water.

[0116] As the alcohols, methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, and the like can be given.

[0117] As the nitriles, acetonitrile, benzonitrile, and the like can be given.

[0118] As the ketones, acetone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, and the like can be given.

[0119] As the amides, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylimidazolidinone, and the like can be given.

[0120] As the sulfoxides, dimethyl sulfoxide, and the like can be given.

[0121] As the ethers, diethyl ether, methyl tert-butyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, and the like can be given.

[0122] As the hydrofluorocarbons, there are, for example, trifluoromethane, difluoromethane, 1,1,1,2-tetrafluoroethane, 1,1,1-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-heptafluoropropane, 1,1,1,3,3-pentafluorobutane, 1,1,1,2,2,3,4,5,5,5-decafluoropentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, and the like.

[0123] As the hydrofluoroethers, there are, for example, methyl 1,1,2,2,2-pentafluoroethyl ether, methyl trifluoromethyl ether, methyl 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane, (2,2,3,3-tetrafluoropropyl)(1,1,2,3,3,3-hexafluoropropyl) ether, (methyl)(nonafluorobutyl) ether, (methyl)(nonafluoroisobutyl) ether, (ethyl)(nonafluorobutyl) ether, (ethyl)(nonafluoroisobutyl) ether, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane, 2-trifluoromethyl-3-ethoxydodecafluorohexane, 1,1,1,2,3-hexafluoro-4-(1,1,2,3,3,3-hexafluoropropoxy)pentane, and the like.

[0124] As the hydrocarbons, there are, for example, butane, pentane, hexane, heptane, octane, nonane, decane, and the like.

[0125] As the aromatic hydrocarbons, there are, for example, benzene, toluene, xylene, mesitylene, perfluorobenzene, and the like.

[0126] It is preferable to use a compound selected from at least one of these solvents as a good solvent or a poor solvent.

[0127] The amount of the solvent at the time of crystallization and precipitation is 50 parts by mass or more and 2000 parts by mass or less, relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4), and is more preferably 100 parts by mass or more and 1000 parts by mass or less.

[0128] When the amount of the solvent is less than 50 parts by mass, relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4), it is difficult to stir the slurry of the fluorine-containing monomer represented by formula (4) that is precipitated by crystallization and precipitation.

[0129] Even if a solvent exceeding 2000 parts by mass is added to dissolve the fluorine-containing monomer represented by formula (4), relative to 100 parts by mass of the fluorine-containing monomer represented by formula (4), the efficiency of removing impurities approaches the upper limit, and it is difficult to improve the cost performance.

[0130] In addition, the content of the fluorine-containing monomer represented by formula (4) in the composition can be measured by gas chromatography.

[0131] In addition, the composition of the present application also contains a composition of the fluorine-containing monomer represented by formula (4) and the fluorine-containing monomer represented by formula (5) after the purification process of the fluorine-containing monomer, and the content of the composition of the fluorine-containing monomer represented by formula (5) is 1500 ppm or less, based on the fluorine-containing monomer represented by formula (4). Furthermore, when the polymerization process is performed as described later, other monomers and organic solvents, in addition to the fluorine-containing monomer represented by formula (4) and the fluorine-containing monomer represented by formula (5), are sometimes added to the composition. The composition containing these is also the composition of the present application.

[0132] < Polymerization process >

[0133] Next, the polymerization process is performed in the method for producing a fluorine-containing polymer of the present application.

[0134] In the polymerization process, the fluorine-containing monomer represented by formula (4) is polymerized by using the composition after the purification process of the fluorine-containing monomer, and a fluorine-containing polymer containing the repeating unit represented by formula (1) is formed.

[0135] In addition, in the composition after the purification process of the fluorine-containing monomer, the fluorine-containing monomer represented by formula (5) which has not been completely removed is contained, and thus the fluorine-containing monomer represented by formula (5) also undergoes polymerization. Therefore, the obtained fluorine-containing polymer contains the repeating unit represented by formula (2).

[0136] In the polymerization process, since the composition having a small content of the fluorine-containing monomer represented by formula (5) is used to polymerize the fluorine-containing monomer represented by formula (4), the deviation of the weight average molecular weight of the fluorine-containing polymer per batch in the obtained fluorine-containing polymer becomes small.

[0137] In addition, in the polymerization process, there is also a case where an unsaturated carboxylic acid or the like which has undergone an addition reaction with the fluorine atom-containing alcohol site of the fluorine-containing monomer represented by formula (5) undergoes polymerization.

[0138] Therefore, the obtained fluorine-containing polymer can contain the repeating unit represented by the following formula (8).

[0139] [Chemical Formula 8]

[0140]

[0141] (In formula (8), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, and R 6 is a hydrogen atom, a chlorine atom, a methyl group or a trifluoromethyl group.)

[0142] Further, in the polymerization step, there are cases where both of the unsaturated carboxylic acid or the like which has undergone an addition reaction with the alkyl alcohol portion not having a fluorine atom of the fluorine-containing monomer represented by Formula (5) and the unsaturated carboxylic acid or the like which has undergone an addition reaction with the fluorine-containing alcohol portion containing a fluorine atom are polymerized.

[0143] Therefore, the obtained fluorine-containing polymer can contain such a repeating unit.

[0144] In the polymerization step, other monomers than the fluorine-containing monomer represented by Formula (4) and the fluorine-containing monomer represented by Formula (5) can be added to the composition after the fluorine-containing monomer purification step, and the polymerization reaction is performed using the composition.

[0145] As the other monomers than the fluorine-containing monomer represented by Formula (4) and the fluorine-containing monomer represented by Formula (5), monomers such as the following monomers can be given.

[0146] That is, monomers having a hexafluoroisopropyl alcohol group (-C(CF3)2OH), acrylic esters, methacrylic esters, fluorine-containing acrylic esters, fluorine-containing methacrylic esters, styrenes, fluorine-containing styrenes, vinyl ethers, fluorine-containing vinyl ethers, allyl ethers, fluorine-containing allyl ethers, unsaturated amides, olefins, fluorine-containing olefins, norbornene compounds, fluorine-containing norbornene compounds, vinyl silanes, vinyl sulfonic acids or vinyl sulfonic acid esters, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, sulfur dioxide, and the like.

[0147] Further, as the other monomers, monomers containing an acid-decomposable group can also be used.

[0148] By using monomers containing an acid-decomposable group to produce a fluorine-containing polymer, when the fluorine-containing polymer is used as a resist, the resist film formed on a substrate is exposed to electromagnetic waves or electron beams or the like high-energy rays having a wavelength of 300 nm or less, whereby the acid-decomposable group is decomposed, and an acid is generated in the resist film.

[0149] By this acid, the solubility of the resist film at the exposed portion in the alkali developing solution in development can be improved.

[0150] Further, as the other monomers, monomers having a lactone structure can also be used.

[0151] By using monomers having a lactone structure to produce a fluorine-containing copolymer, when the fluorine-containing polymer is used as a resist, the adhesion of the resist film containing the fluorine-containing copolymer to a substrate can be improved. Further, when this fluorine-containing copolymer is used in a composition for forming an upper layer film and is made into an upper layer film on a resist pattern, not only the adhesion to a lower resist pattern can be improved, but also the affinity to a developing solution at the time of development can be improved, and a high-fineness resist pattern can be obtained.

[0152] These other monomers can be added singly or two or more kinds can be added.

[0153] As the monomer having a hexafluoroisopropyl alcohol group, the following monomers can be given.

[0154] [Chemical Formula 9]

[0155]

[0156] (R 7 is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group, and the hydrogen atom of the hydroxyl group can be substituted with a protecting group.

[0157] As the acrylic acid esters, the following can be given: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, t-butyl acrylate, 3-oxocyclohexyl acrylate, adamantyl acrylate, methyladamantyl acrylate, ethyladamantyl acrylate, hydroxyadamantyl acrylate, cyclohexyl acrylate, tricyclodecyl acrylate, and the like.

[0158] As the methacrylic acid esters, the following can be given: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, t-butyl methacrylate, 3-oxocyclohexyl methacrylate, adamantyl methacrylate, methyladamantyl methacrylate, ethyladamantyl methacrylate, hydroxyadamantyl methacrylate, cyclohexyl methacrylate, tricyclodecyl methacrylate, and the like.

[0159] As the fluorine-containing acrylic acid esters, fluorine-containing methacrylic acid esters, acrylic acid esters or methacrylic acid esters having a fluorine atom or an alkyl group having a fluorine atom at the α position of the acrylic acid structure, or acrylic acid esters or methacrylic acid esters having a fluorine atom or an alkyl group having a fluorine atom in the ester structure can be given.

[0160] In the fluorine-containing acrylic acid esters or fluorine-containing methacrylic acid esters, a fluorine atom or an alkyl group having a fluorine atom can be introduced at the α position of the acrylic acid structure and in the ester portion. In addition, a cyano group can also be introduced at the α position of the acrylic acid structure.

[0161] In the fluorine-containing acrylic acid esters or fluorine-containing methacrylic acid esters, as the alkyl group having a fluorine atom introduced at the α position of the acrylic acid structure, specifically, the following can be given: a trifluoromethyl group, a trifluoroethyl group, a nonafluoro-n-butyl group.

[0162] In the fluorine-containing propenoate or fluorine-containing methacrylate, the ester structure can have a fluorinated alkyl group such as a perfluoroalkyl group or a fluoroalkyl group. In addition, a cyclic structure and a fluorine atom can coexist in the ester structure. Further, the cyclic structure thereof can have a fluorine-containing benzene ring, a fluorine-containing cyclopentane ring, a fluorine-containing cyclohexane ring, or a fluorine-containing cycloheptane ring having a fluorine atom, a trifluoromethyl group, a hexafluoroisopropyl group, a hydroxyl group, or the like. In addition, the ester structure can be a tertiary butyl ester group having a fluorine atom.

[0163] As such fluorine-containing propenoate, there can be mentioned acrylic acid-2,2,2-trifluoroethyl ester, acrylic acid-2,2,3,3-tetrafluoropropyl ester, acrylic acid-1,1,1,3,3,3-hexafluoroisopropyl ester, acrylic acid heptafluoroisopropyl ester, acrylic acid-1,1-dihydroheptafluoro-n-butyl ester, acrylic acid-1,1,5-trihydrooctafluoro-n-pentyl ester, acrylic acid-1,1,2,2-tetrahydrotridecafluoro-n-octyl ester, acrylic acid-1,1,2,2-tetrahydroheptadecafluoro-n-decyl ester, acrylic acid perfluorocyclohexylmethyl ester, acrylic acid-6-[3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl]bicyclo[2.2.1]heptyl-2-yl ester, acrylic acid-6-[3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl]bicyclo[2.2.1]heptyl-2-yl-2-(trifluoromethyl) ester, acrylic acid-3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl-2-trifluoromethyl ester, and the like.

[0164] As fluorine-containing methacrylate, there can be mentioned methacrylic acid-2,2,2-trifluoroethyl ester, methacrylic acid-2,2,3,3-tetrafluoropropyl ester, methacrylic acid-1,1,1,3,3,3-hexafluoroisopropyl ester, methacrylic acid heptafluoroisopropyl ester, methacrylic acid-1,1-dihydroheptafluoro-n-butyl ester, methacrylic acid-1,1,5-trihydrooctafluoro-n-pentyl ester, methacrylic acid-1,1,2,2-tetrahydrotridecafluoro-n-octyl ester, methacrylic acid-1,1,2,2-tetrahydroheptadecafluoro-n-decyl ester, methacrylic acid perfluorocyclohexylmethyl ester, methacrylic acid-6-[3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl]bicyclo[2.2.1]heptyl-2-yl ester, methacrylic acid-3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl ester, methacrylic acid-3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl ester, and the like.

[0165] As styrene and fluorine-containing styrene, there can be mentioned styrene, hydroxystyrene, fluorinated styrene, and the like.

[0166] As the fluorinated styrene, pentafluorostyrene, trifluoromethylstyrene, bistrifluoromethylstyrene, and the like, which are styrene substituted with a fluorine atom or a trifluoromethyl group instead of hydrogen of the aromatic ring, can be mentioned. In addition, hexafluoroisopropylstyrene, which is styrene substituted with a hexafluoroisopropyl group instead of hydrogen of the aromatic ring, can also be mentioned. In addition, the above-mentioned styrene having a halogen, an alkyl group, or a fluorine-containing alkyl group bonded to the a-position, styrene containing a perfluorovinyl group, and the like can also be mentioned.

[0167] The vinyl ethers, fluorine-containing vinyl ethers, allyl ethers, and fluorine-containing allyl ethers can have a methyl group, an ethyl group, a propyl group, a butyl group, a hydroxyethyl group, or a hydroxybutyl group, or the like, as a hydroxyl group in the structure.

[0168] In addition, these compounds can have a cyclohexyl group, a norbornyl group, or an aromatic ring in the structure, or a cyclic vinyl or allyl ether having a hydrogen, a carbonyl bond, or the like, in the cyclic structure. A part or all of the hydrogen atoms having these structures can be substituted with fluorine atoms.

[0169] As the unsaturated amides, acrylamide, methacrylamide, N-hydroxymethyl acrylamide, N-hydroxymethyl methacrylamide, diacetone acrylamide, and the like can be mentioned.

[0170] As the olefins, ethylene, propylene, isobutylene, cyclopentene, cyclohexene, and the like can be mentioned.

[0171] As the fluorine-containing olefins, fluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, hexafluoroisobutylene, and the like can be mentioned.

[0172] As the monomers having a norbornene site, the norbornene site in the monomer can be one or more, and the hydrogen atoms of the norbornene site can be substituted with a functional group containing a fluorine atom.

[0173] As such monomers, norbornene compounds synthesized by Diels-Alder addition reaction of cyclopentadiene, cyclohexadiene, and an unsaturated compound can be mentioned.

[0174] As the unsaturated compound used in the synthesis of the norbornene compound, acrylic acid, methacrylic acid, a-fluoroacrylic acid, a-trifluoromethylacrylic acid, acrylate, methacrylate, fluorine-containing acrylate, fluorine-containing methacrylate, fluorine-containing olefin, allyl alcohol, fluorine-containing allyl alcohol, homoallyl alcohol, fluorine-containing homoallyl alcohol, 2-(benzyloxy)pentafluoropropane, 2-(methoxyethoxymethyl oxy)pentafluoropropene, 2-(tetrahydroxypyranyl oxy)pentafluoropropene, 2-(benzyloxy)trifluoroethylene, 2-(methoxymethyloxy)trifluoroethylene, 3-(5-bicyclo[2.2.1]hepten-2-yl)-l,l,l-trifluoro-2-(trifluoromethyl)-2-propanol, and the like can be mentioned.

[0175] In the monomer having an acid-decomposable group, the acid-decomposable group can be used without particular limitation as long as it is a group that is detached from the fluorine-containing polymer by hydrolysis with an acid generated from a photoacid generator included in the resist. As such an acid-decomposable group, a monomer having an acid-decomposable group represented by the following formula (9) or formula (10) is preferred.

[0176] [Chemical Formula 10]

[0177]

[0178] (In formula (9) and formula (10), R 8 , R 9 , R 10 , R 12 each independently is a linear alkyl group having 1 to 25 carbon atoms, a branched alkyl group having 3 to 25 carbon atoms, or a cyclic alkyl group, and part or all of the hydrogen atoms included in the alkyl group can be substituted with a fluorine atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a hydroxyl group. R 8 , R 9 , R 10 any two of R 11 is a hydrogen atom, a linear alkyl group having 1 to 25 carbon atoms, a branched alkyl group having 3 to 25 carbon atoms, or a cyclic alkyl group, and part or all of the hydrogen atoms included in the alkyl group can be substituted with a fluorine atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a hydroxyl group. The dotted line is a bonding site.)

[0179] As the acid-decomposable group represented by formula (9) and formula (10), specifically, acid-decomposable groups represented by the following can be given. In addition, the dotted line is a bonding site.

[0180] [Chemical Formula 11]

[0181]

[0182] As the monomer having a lactone structure, monomers having a monocyclic lactone structure such as a group obtained by removing one hydrogen atom from γ-butyrolactone or mevalonolactone, a polycyclic lactone structure such as a group obtained by removing one hydrogen atom from norbornanone, and the like can be given.

[0183] As the other monomers described thus far, 3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl methacrylate represented by the following formula (11) and 1,1,2,2-tetrahydroheptadecafluoron-decyl acrylate represented by the following formula (12) are preferred.

[0184] [Chemical Formula 12]

[0185]

[0186] In the case where 3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl methacrylate is added, when the fluorine-containing polymer is used as a component of an antireflection film or an upper layer film, the solubility in an organic solvent at the time of preparing a coating liquid, the solubility in a developing solution at the time of development are improved.

[0187] In the case where 1,1,2,2-tetrahydroheptadecafluoro-n-decyl acrylate is added, and the obtained fluorine-containing polymer is used as a component of an upper layer film, the adhesion of the upper layer film to a lower layer antireflection film is improved, and the hydrophobicity of the surface of the upper layer film is improved, so that the exposure time in liquid immersion exposure using water as an exposure medium can be shortened. In addition, the surface tension can be reduced, and the smoothing of the surface of the upper layer film and the uniformity of the film thickness can be achieved.

[0188] In the case where other monomers are added, the amount thereof is not particularly limited, and in the fluorine-containing polymer after polymerization, the proportion of the repeating unit from the other monomers is preferably 1 mol% or more and 80 mol% or less, more preferably 5 mol% or more and 70 mol% or less, and further preferably 10 mol% or more and 60 mol% or less, based on 100 mol% of the total repeating units contained in the fluorine-containing polymer.

[0189] If the proportion of the repeating unit from the other monomers is less than 1 mol%, it is difficult to obtain the effects of improving the solubility in an organic solvent when the fluorine-containing polymer is used as an antireflection agent, and improving the adhesion of the antireflection film to a substrate and the etching resistance of an antireflection pattern when the antireflection film is formed on a substrate.

[0190] If the proportion of the repeating unit from the other monomers is more than 80 mol%, the proportion of the repeating unit represented by formula (1) becomes small, and it is difficult to obtain the effects of improving the transparency of the antireflection film and improving the solvent solubility.

[0191] The polymerization reaction in the polymerization step is not particularly limited, and can be a radical polymerization reaction, an ionic polymerization reaction, a coordination anionic polymerization reaction, an active anionic polymerization reaction, or a cationic polymerization reaction.

[0192] Among these, the radical polymerization reaction is preferred.

[0193] In the case where the polymerization reaction is a radical polymerization reaction, as a polymerization initiator, any compound can be used as long as it initiates the polymerization reaction, and there is no particular limitation, and an azo compound, a peroxide compound, or an oxidation-reduction compound can be used.

[0194] As the azo compound, azobisisobutyronitrile can be given.

[0195] As the peroxide compound, t-butyl peroxy neodecanoate, di-t-butyl peroxide, t-butyl peroxy isobutyrate, t-butyl peroxy laurate, peroxy succinic acid, di-cinnamyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, t-butyl peroxy allyl monocarbonate, benzoyl peroxide, hydrogen peroxide, or ammonium persulfate, etc. can be mentioned.

[0196] As the redox compound, a combination of an oxidizing agent and a reducing agent is used, as the oxidizing agent, hydrogen peroxide, persulfate, cumene hydroperoxide, etc. can be mentioned, as the reducing agent, iron (II) ion salt, copper (I) ion salt, ammonia, triethylamine, etc. can be mentioned.

[0197] Further, a polymerization solvent can be used in the radical polymerization reaction.

[0198] As the polymerization solvent, there is no particular limitation as long as it is a solvent which does not hinder the radical polymerization reaction, and it can be an organic solvent or water.

[0199] As the organic solvent, a hydrocarbon-based solvent, an ester-based solvent, a ketone-based solvent, an alcohol-based solvent, an ether-based solvent, a cyclic ether-based solvent, a fluorocarbon-based solvent, an aromatic-based solvent, etc. can be mentioned.

[0200] These solvents can be used singly or in combination of two or more.

[0201] As the ester-based solvent, acetic acid, n-butyl acetate, etc. can be mentioned.

[0202] As the ketone-based solvent, acetone, methyl isobutyl ketone, etc. can be mentioned.

[0203] As the hydrocarbon-based solvent, toluene, cyclohexane, etc. can be mentioned.

[0204] As the alcohol-based solvent, methanol, isopropyl alcohol, ethylene glycol monomethyl ether, etc. can be mentioned.

[0205] Further, in the radical polymerization reaction, a molecular weight adjuster such as a thiol can be used.

[0206] The reaction temperature in the radical polymerization reaction is appropriately changed depending on the radical polymerization initiator or the kind of the radical polymerization initiator, and is preferably 20°C or higher and 200°C or lower, and more preferably 30°C or higher and 140°C or lower.

[0207] After the polymerization step is performed, as a method for removing the organic solvent or water as the medium from the synthesized solution or dispersion liquid containing the fluorine-containing polymer, a publicly known method can be used.

[0208] Specifically, a method such as reprecipitation, filtration, heating distillation under reduced pressure, etc. can be mentioned.

[0209] By the above procedure, a fluorine-containing polymer containing a repeating unit represented by formula (1) and a repeating unit represented by formula (2) can be produced.

[0210] In the polymerization step of the method for producing a fluorine-containing polymer of the present application, it is preferable to synthesize the fluorine-containing polymer so that the relative standard deviation obtained by dividing the standard deviation of the weight average molecular weight of the obtained fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer is preferably 0.10 to 1.10. The relative standard deviation is more preferably 0.10 to 0.60.

[0211] In addition, in the present specification, the "standard deviation of the weight average molecular weight of the obtained fluorine-containing polymer" means the standard deviation of the weight average molecular weight of six batches of the fluorine-containing polymer produced under the same conditions.

[0212] Further, in the present specification, the weight average molecular weight of the fluorine-containing polymer means the value determined by gel permeation chromatography (GPC) under the following conditions.

[0213] [GPC conditions]

[0214] Apparatus: HLC-8320 GPC manufactured by Tosoh Corporation

[0215] Chromatographic column for analysis of polymerizable monomers: TSKgel series (G2500HXL, G2000HXL, G1000HXL, G1000HXL connected in series in this order) manufactured by Tosoh Corporation

[0216] Chromatographic column for analysis of polymers: TSKgel series (G2500HXL, G2000HXL, G1000HXL, G1000HXL connected in series in this order) manufactured by Tosoh Corporation

[0217] Temperature program: 40°C (hold)

[0218] Flow rate: 1 mL / minute

[0219] Detector: differential refractive detector (RI)

[0220] Eluent: tetrahydrofuran (THF)

[0221] Reference substance: polystyrene standard solution

[0222] In the fluorine-containing monomer purification step of the method for producing a fluorine-containing polymer of the present application, the above relative standard deviation of 0.10 to 1.10 can be obtained by sufficiently removing the fluorine-containing monomer represented by formula (5) from the composition.

[0223] Thus, the deviation of the weight average molecular weight of the fluorine-containing polymer per batch is small, and therefore, the alkali solubility does not easily change when the fluorine-containing polymer is used to form a resist pattern, and adjustment of the exposure and development conditions becomes easy. Furthermore, when a fine resist pattern is formed, the pattern obtained after the development process does not easily have unevenness.

[0224] Furthermore, if the weight average molecular weight of the fluorine-containing polymer per batch deviates, when the fluorine-containing polymer is used to form a fine resist pattern, the pattern obtained after the development process sometimes has unevenness.

[0225] However, the weight average molecular weight of the fluorine-containing polymer per batch is small in the fluorine-containing polymer manufactured by the manufacturing method of the fluorine-containing polymer of the present application. Therefore, when the fluorine-containing polymer obtained in the present application is used to form a fine resist pattern, the smoothness of the surface of the pattern obtained after the development process is good.

[0226] The weight average molecular weight of the obtained fluorine-containing polymer is preferably 5000 to 20000, and more preferably 7000 to 12000.

[0227] The obtained fluorine-containing polymer can be used as a component of a resist film or an upper film for protecting a resist pattern.

[0228] Furthermore, the resist film and the resist pattern formed using the obtained fluorine-containing polymer have high transparency and high solvent solubility.

[0229] Hereinafter, specific examples of the present application will be shown, but the present application is not limited to the following examples.

[0230] (Preparation of a standard sample of the monomer represented by Formula (4))

[0231] <Fluorine-containing monomer synthesis process>

[0232] Into a 1 L three-necked flask having a thermometer, a reflux condenser, and a stirrer, 100 g (0.44 mol) of 1,1,1-trifluoro-2-(trifluoromethyl)pentane-1,3-diol (a compound represented by Formula (3-1) shown below), 74.6 g (0.48 mol) of methacrylic anhydride, 4.2 g (0.044 mol) of methanesulfonic acid, 400 g of toluene, and 0.5 g of phenothiazine were added. Then, the bottom of the three-necked flask was immersed in an oil bath adjusted to 50°C, and the reaction was performed with stirring for 4 hours to obtain a composition.

[0233] The composition was measured by gas chromatography, and as a result, it was confirmed that the methyl methacrylate-5, 5, 5-trifluoro-4-hydroxy-4-trifluoromethylpentan-2-yl ester (compound represented by formula (4-1)) contained in the reaction solution was 94.5 mass%, 1, 1, 1-trifluoro-2- (trifluoromethyl) pentane-1, 3-diol was 1.6 mass%, methacrylic anhydride was 2.0 mass%, and other compounds were 1.9 mass% excluding methyl methacrylate as a by-product.

[0234] [Chemical Formula 13]

[0235]

[0236] <Fluorine-containing monomer purification step>

[0237] The obtained composition was added to a separatory funnel, 400 g of sodium bicarbonate water was added, washed twice, and then the organic layer was collected. 30 g of magnesium sulfate was added, dried, and then the magnesium sulfate was removed by filtration. To the filtrate, 0.7 g of phenothiazine as a polymerization inhibitor was added, and after distilling off the solvent, it was subjected to reduced pressure distillation (8 Torr = 1.1 kPa) to collect a fraction of 80°C to 82°C to obtain 112 g of a fraction. The yield was 87%.

[0238] The fraction was analyzed by gas chromatography mass spectrometry (GC-MS), and as a result, the purity of the methyl methacrylate-5, 5, 5-trifluoro-4-hydroxy-4-trifluoromethylpentan-2-yl ester (fluorine-containing monomer represented by formula (4-1)) as a target substance was 97.0%, and the methyl methacrylate-1, 1, 1-trifluoro-2- (trifluoromethyl) pentane-2, 4-diyl ester (fluorine-containing monomer represented by formula (5-1) below) as a by-product was contained.

[0239] [Chemical Formula 14]

[0240]

[0241] The above operation was repeated to produce 3.0 kg of a fraction containing methyl methacrylate-5, 5, 5-trifluoro-4-hydroxy-4-trifluoromethylpentan-2-yl ester (fluorine-containing monomer represented by formula (4-1)).

[0242] The obtained fraction was subjected to precision distillation using an Oldershaw distillation column, and 2.76 kg of a fraction having a boiling point of 80°C was obtained at a pressure of 0.5 kPa.

[0243] The obtained fraction was measured by GC-MS, and as a result, the purity of the methyl methacrylate-5, 5, 5-trifluoro-4-hydroxy-4-trifluoromethylpentan-2-yl ester (fluorine-containing monomer represented by formula (4-1)) was 99.8%.

[0244] The concentration of the methacrylic acid-1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl ester (fluorine-containing monomer represented by Formula (5-1)) measured by GC-MS before the precision distillation was 2600 ppm, but was reduced to 10 ppm after the precision distillation. A composition of the methacrylic acid-5,5,5-trifluoro-4-hydroxy-4-trifluoromethylpentane-2-yl ester (fluorine-containing monomer represented by Formula (4-1)) having the purity improved by the precision distillation was obtained in this way. This composition was used as a standard sample of the methacrylic acid-5,5,5-trifluoro-4-hydroxy-4-trifluoromethylpentane-2-yl ester (fluorine-containing monomer represented by Formula (4-1)).

[0245] Further, a standard sample of the methacrylic acid-1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl ester (fluorine-containing monomer represented by Formula (5-1)) was produced by the following method.

[0246] A 1L three-necked flask equipped with a thermometer, a reflux condenser, and a stirrer was charged with 100 g of the standard sample of the methacrylic acid-5,5,5-trifluoro-4-hydroxy-4-trifluoromethylpentane-2-yl ester (fluorine-containing monomer represented by Formula (4-1)), 60 g of triethylamine, 4 g of N,N-dimethylaminopyridine, and 1 g of phenothiazine. The bottom of the flask was immersed in an ice bath, and 79 g of methacrylic anhydride was added dropwise with stirring, followed by returning to room temperature, stirring for one hour, and obtaining a reaction solution. The reaction solution was transferred to a separatory funnel, diluted with 300 g of toluene, and then 200 mL of dilute hydrochloric acid was added to terminate the reaction, and the organic layer was separated. The separated organic layer was washed with 200 g of water twice, and then the solvent was distilled off using a rotary evaporator. Next, distillation was performed using a distillation apparatus equipped with a Wiped-Film evaporator. A fraction was collected at 86°C to 88°C under a vacuum degree of 0.5 kPa, and 16 g of an oily fraction was obtained. The methacrylic acid-1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl ester (fluorine-containing monomer represented by Formula (5-1)) contained in the oily fraction was 96 mass% and the unreacted methacrylic acid-5,5,5-trifluoro-4-hydroxy-4-trifluoromethylpentane-2-yl ester (fluorine-containing monomer represented by Formula (4-1)) was 2.5 mass% as measured by GC-MS. This oily fraction was used as a standard sample of the methacrylic acid-1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl ester (fluorine-containing monomer represented by Formula (5-1)).

[0247] (Production of a raw material composition used in the polymerization step)

[0248] Using a standard sample of the prepared methyl methacrylate-5,5,5-trifluoro-4- hydroxy-4-trifluoromethylpentan-2-yl ester (fluorine-containing monomer represented by Formula (4-1)) and a standard sample of methyl methacrylate-1,1,1-trifluoro-2- (trifluoromethyl)pentan-2,4-diyl ester (fluorine-containing monomer represented by Formula (5-1)), raw material compositions A to F were prepared in the proportions shown in Table 1.

[0249] [Table 1]

[0250]

[0251] (Example 1)

[0252] <Polymerization Step>

[0253] At room temperature (about 20°C), 100 g of the raw material composition A was added to a 500 mL container, and 200 g of 2-butanone in which 6.26 g of dimethyl-2,2'-azobis(2-methylpropanate) (manufactured by Wako Pure Chemical Industries, Ltd., product name V-601) was dissolved was added, and after the solution of the raw material composition A was prepared, it was transferred to a dropping funnel. Next, the dropping funnel was attached to a 500 mL reactor in which 100 g of 2-butanone was charged, and the 2-butanone was warmed to 78°C.

[0254] While the temperature of the 2-butanone in the reactor was maintained at 78 ± 1°C, the solution of the raw material composition A was slowly added dropwise over 2 hours to the reactor under a stream of nitrogen. After the addition was completed, the temperature was maintained at 78 ± 1°C for 6 hours and then cooled. At this time, the temperature was slowly lowered to 30°C over 30 minutes, and a fluorine-containing polymer containing the repeating unit represented by the following Formula (1-1) was obtained. The obtained fluorine-containing polymer was the fluorine-containing polymer of Example 1.

[0255] The molecular weight of the fluorine-containing polymer of Example 1 was measured by gel permeation chromatography (GPC), and the result was a weight average molecular weight of 9575 (N = 1).

[0256] [Chemical Formula 15]

[0257]

[0258] The fluorine-containing polymer of Example 1 was similarly produced 5 times (N = 2 to 6) for a total of 6 times. The weight average molecular weight of the fluorine-containing polymer of Example 1 in each production was measured. In addition, the relative standard deviation (RSD) was obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The result is shown in Table 2.

[0259] Next, the reaction solution containing the fluorine-containing polymer was slowly added to n-heptane, whose temperature was adjusted to 25°C, over 1 hour while stirring, and further stirred for 1 hour to obtain a slurry of the fluorine-containing polymer. The obtained slurry was filtered under reduced pressure to obtain a filter cake. The filter cake was dried to thereby obtain a powder of the fluorine-containing polymer of Example 1.

[0260] (Examples 2) to (5)

[0261] Using the raw material composition B to the raw material composition E instead of the raw material composition A, otherwise similarly to Example 1, the fluorine-containing polymers of Examples 2 to 5 were respectively produced. Then, the weight average molecular weight of the fluorine-containing polymers of Examples 2 to 5 was measured, and the relative standard deviation was calculated from the standard deviation of the weight average molecular weight of the fluorine-containing polymers divided by the average value of the weight average molecular weight of the fluorine-containing polymers. The results are shown in Table 2.

[0262] (Example 6)

[0263] At room temperature (about 20°C), 80 g of the raw material composition A, 20 g of 3,5-bis(l,l,l,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl methacrylate (a monomer represented by Formula (11)) were added to a 500 mL container, and 200 g of 2-butanone in which 6.26 g of dimethyl-2,2'-azobis(2-methylpropanate) (manufactured by Wako Pure Chemical Industries, Ltd., product name V-601) was dissolved was added, and after making a mixed solution with the raw material composition A, it was transferred to a dropping funnel. Next, the dropping funnel was attached to a 500 mL reactor in which 100 g of 2-butanone was charged, and the 2-butanone was warmed to 78°C.

[0264] While the temperature of the 2-butanone in the reactor was maintained at 78 ± 1°C, the above mixed solution was slowly added to the reactor over 2 hours under a stream of nitrogen gas. After the addition was completed, the temperature was maintained at 78 ± 1°C for 6 hours and then cooled. At this time, the temperature was slowly lowered to 30°C over 30 minutes to obtain a fluorine-containing polymer containing the repeating unit represented by the following Formula (1-1) and the repeating unit represented by the following Formula (11-1). The obtained fluorine-containing polymer was the fluorine-containing polymer of Example 6.

[0265] Next, the 2-butanone was removed from the reaction solution, and the molecular weight of the fluorine-containing polymer of Example 6 was measured by GPC, and the result was 9669 (N = 1).

[0266] [Chemical Formula 16]

[0267]

[0268] The reaction solution of the fluorine-containing polymer of Example 6 was produced five times (N = 2 to 6) in the same manner as in Example 6, for a total of six times. The weight average molecular weight of the fluorine-containing polymer of Example 6 in each production was measured. In addition, the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0269] (Example 7)

[0270] The fluorine-containing polymer of Example 7 was produced in the same manner as in Example 6, except that the raw material composition C was used instead of the raw material composition A. Then, the weight average molecular weight of the fluorine-containing polymer of Example 7 was measured, and the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0271] (Example 8)

[0272] At room temperature (about 20°C), 95 g of the raw material composition A, 5 g of 1,1,2,2-tetrahydrogen heptadecafluoro-n-decyl acrylate (monomer represented by Formula (12)) were added to a 500 mL container, and 200 g of 2-butanone in which 6.26 g of dimethyl-2,2'-azobis(2-methylpropanate) was dissolved was added, and after making a mixed solution with the raw material composition A, it was transferred to a dropping funnel. Next, the dropping funnel was installed on a 500 mL reactor in which 100 g of 2-butanone was installed, and the 2-butanone was warmed to 78°C.

[0273] While the temperature of the 2-butanone in the reactor was maintained at 78 ± 1°C, the above mixed solution was slowly dropped into the reactor through the dropping funnel under a nitrogen stream for 2 hours. After the dropping was completed, it was cooled after maintaining the temperature at 78 ± 1°C for 6 hours. At this time, the temperature was lowered to 30°C over 30 minutes, and a fluorine-containing polymer containing the repeating unit represented by the following Formula (1-1) and the repeating unit represented by the following Formula (12-1) was obtained. The obtained fluorine-containing copolymer was the fluorine-containing polymer of Example 8.

[0274] The molecular weight of the fluorine-containing copolymer of Example 8 obtained by removing the 2-butanone from the reaction solution was measured by gel permeation chromatography (GPC), and the weight average molecular weight was 9532 (N = 1).

[0275] [Chemical Formula 17]

[0276]

[0277] The reaction solution of the fluorine-containing polymer of Example 8 was produced five times (N = 2 to 6) in the same manner as in Example 8, for a total of six times. The weight average molecular weight of the fluorine-containing polymer of Example 8 in each production was measured. In addition, the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0278] (Example 9)

[0279] The fluorine-containing polymer of Example 9 was produced in the same manner as in Example 8, except that the raw material composition C was used instead of the raw material composition A. Then, the weight average molecular weight of the fluorine-containing polymer of Example 9 was measured, and the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0280] (Comparative Example 1)

[0281] The fluorine-containing polymer of Comparative Example 1 was produced in the same manner as in Example 1, except that the raw material composition F was used instead of the raw material composition A. Then, the weight average molecular weight of the fluorine-containing polymer of Comparative Example 1 was measured, and the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0282] (Comparative Example 2)

[0283] The fluorine-containing polymer of Comparative Example 2 was produced in the same manner as in Example 8, except that the raw material composition F was used instead of the raw material composition A. Then, the weight average molecular weight of the fluorine-containing polymer of Comparative Example 2 was measured, and the relative standard deviation was calculated as the value obtained by dividing the standard deviation of the weight average molecular weight of the fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer. The results are shown in Table 2.

[0284] [Table 2]

[0285]

[0286] As shown in Table 2, the value of the RSD of the fluorine-containing polymers of Examples 1 to 9 produced using the raw material composition in which the concentration of the 1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl methacrylate (fluorine-containing monomer represented by Formula (5-1)) was 1500 ppm or less was a small value.

[0287] On the other hand, the RSD of the fluorine-containing polymers of Comparative Examples 1 and 2 produced using the raw material composition F in which the concentration of the 1,1,1-trifluoro-2-(trifluoromethyl)pentane-2,4-diyl methacrylate (fluorine-containing monomer represented by Formula (5-1)) was greater than 1500 ppm was a large value.

Claims

1. A method for producing a fluorine-containing polymer, characterized by, A method for producing a fluorine-containing polymer containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), the production method comprising the following steps: A fluorine-containing monomer synthesis step of reacting a diol represented by the following formula (3) with at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the unsaturated carboxylic acid, an acid halide of the unsaturated carboxylic acid, and an acid anhydride of the unsaturated carboxylic acid to obtain a composition containing a fluorine-containing monomer represented by the following formula (4) as a main reaction product and a fluorine-containing monomer represented by the following formula (5) as a side reaction product; A fluorine-containing monomer purification step of removing the fluorine-containing monomer represented by the formula (5) from the composition to make the content of the fluorine-containing monomer represented by the formula (5) 500 ppm or less in terms of mass parts per million based on the fluorine-containing monomer represented by the formula (4); A polymerization step of performing a polymerization reaction using the composition after the fluorine-containing monomer purification step to produce a fluorine-containing polymer containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2); In formula (1), formula (2), formula (3), formula (4), and formula (5), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group, or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, and R 6 is a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.

2. The method for producing a fluoropolymer according to claim 1, wherein, In the polymerization step, the fluorine-containing polymer is synthesized in such a manner that the relative standard deviation, which is a value obtained by dividing the standard deviation of the weight average molecular weight of the obtained fluorine-containing polymer by the average value of the weight average molecular weight of the fluorine-containing polymer, becomes 0.10 to 1.

10.

3. The method for producing a fluoropolymer according to claim 1 or 2, wherein, R 5 is trifluoromethyl.

4. The method for producing a fluoropolymer according to claim 1 or 2, wherein, R 3 and R 4 is a hydrogen atom.

5. The method for producing a fluoropolymer according to claim 1 or 2, wherein, R 1 is a methyl group or an isopropyl group, R 2 is a hydrogen atom.

6. The method for producing a fluoropolymer according to claim 1 or 2, wherein, In the diol represented by the formula (3), R 1 is a methyl group or an isopropyl group, R 2 ~R 4 is a hydrogen atom, R 5 is a trifluoromethyl group.

7. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The fluorine-containing monomer represented by the formula (4) is a fluorine-containing monomer represented by the following formula (4-1) or a fluorine-containing monomer represented by the following formula (4-2), 。 8. The method for producing a fluoropolymer according to claim 1 or 2, wherein, The at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the unsaturated carboxylic acid, an acid halide of the unsaturated carboxylic acid, and an acid anhydride of the unsaturated carboxylic acid contains a methacrylic acid agent.

9. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The reaction conditions of the reaction are 30 to 130°C for 0.5 to 8 hours.

10. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The molar ratio of the diol represented by the formula (3) to the at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the unsaturated carboxylic acid, an acid halide of the unsaturated carboxylic acid, and an acid anhydride of the unsaturated carboxylic acid is [molar amount of the diol represented by the formula (3)] : [molar amount of the at least one selected from the group consisting of an unsaturated carboxylic acid, an ester of the unsaturated carboxylic acid, an acid halide of the unsaturated carboxylic acid, and an acid anhydride of the unsaturated carboxylic acid] = 1 : 0.7 to 1 : 1.

3.

11. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The content of the fluorine-containing monomer represented by the formula (5) is 450 ppm or less.

12. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The content of the fluorine-containing monomer represented by the formula (5) is 200 ppm or less.

13. The method of producing a fluoropolymer according to claim 1 or 2, wherein, In the polymerization step, a polymerization reaction is performed using the composition containing another monomer other than the fluorine-containing monomer represented by the formula (4) and the fluorine-containing monomer represented by the formula (5).

14. The method of producing a fluoropolymer according to claim 13, wherein, The other monomer includes at least one selected from the group consisting of a monomer containing an acid-decomposable group, a monomer having a lactone structure, a monomer having a hexafluoroisopropyl alcohol group, acrylic esters, methacrylic esters, fluorine-containing acrylic esters, fluorine-containing methacrylic esters, styrenes, fluorine-containing styrenes, vinyl ethers, fluorine-containing vinyl ethers, allyl ethers, fluorine-containing allyl ethers, unsaturated amides, olefins, fluorine-containing olefins, norbornene compounds, fluorine-containing norbornene compounds, vinyl silanes, vinyl sulfonic acids, vinyl sulfonic acid esters, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and sulfur dioxide.

15. The method of producing a fluoropolymer according to claim 13, wherein, The other monomer includes at least one selected from the group consisting of 3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl methacrylate and 1,1,2,2-tetrahydroheptadecafluorononyl acrylate.

16. The method of producing a fluoropolymer according to claim 13, wherein, The proportion of repeating units from the other monomer is 1 mol% or more and 80 mol% or less, based on 100 mol% of the total repeating units of the fluorine-containing polymer.

17. The method of producing a fluoropolymer according to claim 13, wherein, The proportion of repeating units from the other monomer is 5 mol% or more and 70 mol% or less, based on 100 mol% of the total repeating units of the fluorine-containing polymer.

18. The method of producing a fluoropolymer according to claim 13, wherein, The proportion of repeating units from the other monomer is 10 mol% or more and 60 mol% or less, based on 100 mol% of the total repeating units of the fluorine-containing polymer.

19. The method of producing a fluoropolymer according to claim 2, wherein, The relative standard deviation is 0.10 to 0.

60.

20. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The weight average molecular weight of the fluorine-containing polymer is 5000 to 20000.

21. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The weight average molecular weight of the fluorine-containing polymer is 7000 to 12000.

22. The method of producing a fluoropolymer according to claim 1 or 2, wherein, The polymerization reaction in the polymerization step is a radical polymerization reaction.

23. The method of making a fluoropolymer according to claim 22, wherein, The radical polymerization reaction is performed in an organic solvent.

24. A composition comprising, The composition contains a fluorine-containing monomer represented by the following formula (4) and a fluorine-containing monomer represented by the following formula (5) at 500 ppm or less of the fluorine-containing monomer represented by the formula (4) in terms of mass per million, In formula (4) and formula (5), R 1 , R 2 each independently is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, or a t-butyl group, R 3 , R 4 each independently is a hydrogen atom, a methyl group, or an ethyl group, R 5 is a hydrogen atom or a trifluoromethyl group, R 6 is a hydrogen atom, a chlorine atom, a methyl group, or a trifluoromethyl group.

25. The composition of claim 24, wherein, R 5 is trifluoromethyl.

26. The composition of claim 24 or 25, wherein, R 3 , R 4 is a hydrogen atom.

27. The composition of claim 24 or 25, wherein, R 1 is a methyl group or an isopropyl group, R 2 is a hydrogen atom.

28. The composition of claim 24 or 25, wherein, The content of the fluorine-containing monomer represented by the formula (5) is 450 ppm or less.

29. The composition of claim 24 or 25, wherein, The content of the fluorine-containing monomer represented by the formula (5) is 200 ppm or less.

30. The composition of claim 24 or 25, wherein, The composition further contains an other monomer than the fluorine-containing monomer represented by the formula (4) and the fluorine-containing monomer represented by the formula (5).

31. The composition of claim 30, wherein, The other monomer includes at least one selected from the group consisting of a monomer containing an acid-decomposable group, a monomer having a lactone structure, a monomer having a hexafluoroisopropyl alcohol group, acrylic esters, methacrylic esters, fluorine-containing acrylic esters, fluorine-containing methacrylic esters, styrenes, fluorine-containing styrenes, vinyl ethers, fluorine-containing vinyl ethers, allyl ethers, fluorine-containing allyl ethers, unsaturated amides, olefins, fluorine-containing olefins, norbornene compounds, fluorine-containing norbornene compounds, vinyl silanes, vinyl sulfonic acids, vinyl sulfonic acid esters, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and sulfur dioxide.

32. The composition of claim 30, wherein, The other monomer comprises at least one selected from the group consisting of 3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl)cyclohexyl methacrylate and 1,1,2,2-tetrahydroheptadecafluoro-n-decyl acrylate.

33. The composition of claim 24 or 25, wherein, The composition further comprises an organic solvent.

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