Aromatic polysulfone, method for producing aromatic polysulfone, resin composition, and prepreg

Abstract

Provided is an aromatic polysulfone having a repeating unit represented by formula (1) and a repeating unit represented by formula (2), wherein the number of repeating units represented by formula (2) is 55% or more relative to the total of 100% of all repeating units constituting the aromatic polysulfone. In formula (1), R1 and R2 each independently represent an alkyl group. In formula (2), R3 and R4 each independently represent a halogen atom, a phenyl group, a C1-6 alkyl group, or a C2-10 alkenyl group, and m and n each independently represent an integer of 0-4. When there are a plurality of R3 or R4, they may be the same or different.

Description

Aromatic polysulfone, method for producing aromatic polysulfone, resin composition, and prepreg

[0001] The present invention relates to an aromatic polysulfone, a method for producing the aromatic polysulfone, a resin composition, and a prepreg. This application claims priority based on Japanese Patent Application No. 2023-108837, filed on June 30, 2023, the contents of which are incorporated herein by reference.

[0002] Aromatic polysulfones have a high glass transition temperature (Tg) and are used in many fields, including electronic materials, as materials with excellent heat resistance. For example, Patent Document 1 discloses an aromatic polysulfone capable of exhibiting a high glass transition temperature (Tg), a prepreg using the aromatic polysulfone and a liquid epoxy resin, and a method for producing the prepreg.

[0003] Japanese Patent Application Publication No. 2017-141427

[0004] The present inventors have found that aromatic polysulfones having repeating units derived from bisphenols having a fluorene skeleton tend to exhibit a high glass transition temperature (Tg). However, when such aromatic polysulfones having an improved glass transition temperature are used in the production of prepregs, they have a problem in that they have poor solubility in epoxy resins.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide an aromatic polysulfone having repeating units derived from a bisphenol having a fluorene skeleton, wherein the aromatic polysulfone has enhanced solubility in an epoxy resin. Another object of the present invention is to provide a resin composition containing the aromatic polysulfone and an epoxy resin. Another object of the present invention is to provide a prepreg containing the resin composition and reinforcing fibers.

[0006] The present inventors have conducted extensive research to solve the above problems and have found that an aromatic polysulfone having a specific structural repeating unit represented by formula (1) described below and a predetermined proportion of a repeating unit represented by formula (2) described below has excellent solubility in epoxy resins, thereby completing the present invention.

[0007] <1> An aromatic polysulfone having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), wherein the number of repeating units represented by the formula (2) is 55% or more relative to 100% of the total number of all repeating units constituting the aromatic polysulfone.

[0008] [In formula (1), R １ and R ２ each independently represents an alkyl group.

[0009] [In formula (2), R ３ and R ４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and m and n each independently represent an integer of 0 to 4. ３ or R ４ When there are multiple, they may be the same or different.

[0010] <2> The R １ and the R ２ is a methyl group. <3> The aromatic polysulfone according to <1> or <2>, wherein the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone is less than 70 μmol / g. <4> The aromatic polysulfone according to any one of <1> to <3>, wherein the weight average molecular weight is 30,000 or more and 70,000 or less.

[0011] <5> A method for producing an aromatic polysulfone, comprising a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain an aromatic polysulfone, wherein the dihydroxy compound comprises a compound represented by the following formula (1a) and a compound represented by the following formula (2a), and the dihalogeno compound comprises a compound represented by the following formula (2b):

[0012] [In formula (1a), R １１ and R １２ each independently represents an alkyl group.

[0013] [In formula (2a), R １３ and R １４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and p and q each independently represent an integer of 0 to 4. １３ or R １４ When there are multiple, they may be the same or different.

[0014] [In formula (2b), X １ and X ２ each independently represents a halogen atom. １ and X ２ may be the same or different. １５ and R １６ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and r and s each independently represent an integer of 0 to 4. １５ or R １６ When there are multiple, they may be the same or different.

[0015] <6> The method for producing an aromatic polysulfone according to <5>, wherein in the polymerization step, the dihydroxy compound includes dihydroxydiphenyl sulfone and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the dihalogeno compound includes dihalogenodiphenyl sulfone.

[0016] <7> The method for producing an aromatic polysulfone according to <5> or <6>, wherein in the polymerization step, the molar ratio of the dihydroxy compound to the dihalogeno compound satisfies the condition of the following formula (II): dihydroxy compound / dihalogeno compound≦1 Formula (II)

[0017] <8> A resin composition comprising the aromatic polysulfone according to any one of <1> to <4> and an epoxy resin. <9> The resin composition according to <8>, further comprising a curing agent.

[0018] <10> A prepreg comprising the resin composition according to <9> above and reinforcing fibers. <11> The prepreg according to <10> above, wherein the reinforcing fibers are carbon fibers.

[0019] According to the present invention, there is provided an aromatic polysulfone having a repeating unit derived from a bisphenol having a fluorene skeleton, the aromatic polysulfone having enhanced solubility in an epoxy resin. The present invention also provides a resin composition containing the aromatic polysulfone and an epoxy resin. The present invention also provides a prepreg containing the resin composition and reinforcing fibers.

[0020] Hereinafter, embodiments of the aromatic polysulfone, the method for producing the aromatic polysulfone, the resin composition, and the prepreg of the present invention will be described.

[0021] <Aromatic Polysulfone> In this specification, the term "aromatic polysulfone" refers to a polysulfone comprising a divalent aromatic group (a residue obtained by removing two hydrogen atoms bonded to an aromatic ring from an aromatic compound), an ether bond (-O-), and a sulfonyl group (-SO ２ The aromatic polysulfone of the embodiment is an aromatic polysulfone having a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as "repeating unit (1)") and a repeating unit represented by the following formula (2) (hereinafter sometimes referred to as "repeating unit (2)"), in which the number of the repeating units (2) is 55% or more relative to 100% of the total number of all repeating units constituting the aromatic polysulfone.

[0022] [In formula (1), R １ and R ２ each independently represents an alkyl group.

[0023] Regarding the repeating unit (1), in the formula (1), R １ and R ２ Examples of the alkyl group in include alkyl groups having 1 to 6 carbon atoms, and preferred examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, an n-decyl group, etc. The alkyl group may be linear or branched.

[0024] From the viewpoint of improving the solubility of the aromatic polysulfone in the epoxy resin, in the formula (1), R １ and R ２ are each independently preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and R １ and R ２ More preferably, each of R is a methyl group, １ and R ２ are particularly preferably methyl groups.

[0025] [In formula (2), R ３ and R ４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and m and n each independently represent an integer of 0 to 4. ３ or R ４ When there are multiple, they may be the same or different.

[0026] Regarding the repeating unit (2), in the formula (2), R ３ and R ４ The alkyl group in the formula (1) is １ and R ２ In the formula (2), R ３ and R ４ The alkenyl group in formula (1) is R１ and R ２ In the alkyl groups exemplified above, one single bond (C-C) between carbon atoms is substituted with a double bond (C=C), and the position of the double bond is not limited.

[0027] In the formula (2), m and n are each preferably 0.

[0028] In the aromatic polysulfone, the number of repeating units (2) is 55% or more, preferably 60% or more, and more preferably 65% ​​or more, of the total number of all repeating units constituting the aromatic polysulfone (100%). Aromatic polysulfones having repeating units (2) at or above the lower limit above have improved solubility in epoxy resins, a higher thermal decomposition temperature, and excellent heat resistance.

[0029] The aromatic polysulfone preferably contains 55% to 98% of the repeating unit (2), more preferably 60% to 95%, and even more preferably 65% ​​to 95%, of the total number of all repeating units constituting the aromatic polysulfone (100%).

[0030] The aromatic polysulfone of this embodiment may contain, for example, 55% to 98% of repeating units (2) and 2% to 45% of repeating units (1), relative to 100% of the total number of all repeating units constituting the aromatic polysulfone; 60% to 95% of repeating units (2) and 5% to 40% of repeating units (1); or 65% to 95% of repeating units (2) and 5% to 35% of repeating units (1).

[0031] In addition to the repeating unit (1) and the repeating unit (2), the aromatic polysulfone may further have one or more other repeating units such as a repeating unit represented by the following formula (3) (hereinafter sometimes referred to as "repeating unit (3)") or a repeating unit represented by the following formula (4) (hereinafter sometimes referred to as "repeating unit (4)").

[0032] (3)-Ph ３ -R-Ph ４-O- [wherein, Ph ３ and Ph ４ each independently represents a phenylene group. A hydrogen atom in the phenylene group may be independently substituted with an alkyl group, an aryl group, a halogen atom, a sulfo group, a nitro group, an amino group, a carboxyl group, or a hydroxyl group. R represents an alkylidene group, an oxygen atom, or a sulfur atom.

[0033] (4)-(Ph ５ ) ｔ -O- [wherein, Ph ５ represents a phenylene group. Each hydrogen atom in the phenylene group may be independently substituted with an alkyl group, an aryl group, a halogen atom, a sulfo group, a nitro group, an amino group, a carboxyl group, or a hydroxyl group. t represents an integer of 1 to 3. When t is 2 or more, a plurality of Ph ５ may be the same or different from each other.

[0034] Ph ３ ~Ph ５ The phenylene group represented by any one of the following formulae may be a p-phenylene group, an m-phenylene group, or an o-phenylene group, but is preferably a p-phenylene group.

[0035] The number of carbon atoms in the alkyl group which may substitute a hydrogen atom in the phenylene group of the formulas (3) and (4) is preferably 1 to 10. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, and an n-decyl group.

[0036] The number of carbon atoms in the aryl group which may substitute a hydrogen atom in the phenylene group of the formulas (3) and (4) is preferably 6 to 20. Specific examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0037] Examples of the halogen atom which may substitute a hydrogen atom in the phenylene group of the formulas (3) and (4) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0038] When hydrogen atoms in the phenylene groups of the repeating units (3) and (4) are substituted with these groups, the number of such groups is, independently for each phenylene group, preferably 2 or less, and more preferably 1. Among the above, it is preferable that the hydrogen atoms in the phenylene groups of the repeating units (3) and (4) are not substituted.

[0039] The alkylidene group represented by R preferably has 1 to 5 carbon atoms. Specific examples include a methylene group, an ethylidene group, an isopropylidene group, and a 1-butylidene group.

[0040] The aromatic polysulfone of the embodiment may have two or more repeating units (3) and (4) independently in addition to the repeating unit (1) and the repeating unit (2). Among these, the aromatic polysulfone having only the repeating unit (1) and the repeating unit (2) as repeating units is more preferred.

[0041] The aromatic polysulfone of the embodiment may have a hydroxyl group and / or a salt thereof in its molecule. The salt of the hydroxyl group may be composed of an oxyanion group formed by dissociating a proton from the hydroxyl group and a counter cation. Examples of the counter cation include alkali metal ions such as lithium ions, sodium ions, and potassium ions; alkaline earth metal ions such as magnesium ions and calcium ions; and ammonium ions and quaternary ammonium ions formed by protonating ammonia or primary, secondary, or tertiary amines. When the counter cation is a polyvalent cation such as an alkaline earth metal ion, the counter anion may be composed of multiple oxyanion groups, or may be composed of an oxyanion group and another anion such as a chloride ion or hydroxide ion.

[0042] The hydroxyl group and / or salt thereof may be located at a terminal of the main chain of the aromatic polysulfone, i.e., the aromatic polysulfone may have at least one terminal hydroxyl group and / or salt thereof at the terminal of the main chain of the aromatic polysulfone.

[0043] In the aromatic polysulfone of the embodiment, the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone is preferably less than 70 μmol / g, more preferably 65 μmol / g or less, and even more preferably less than 65 μmol / g. When the aromatic polysulfone contains hydroxyl groups and / or salts thereof in an amount less than the above upper limit, the cured product of a resin composition containing the aromatic polysulfone and an epoxy resin can exhibit superior heat resistance.

[0044] The amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone may be 10 μmol / g or more, 15 μmol / g or more, or 20 μmol / g or more. The numerical range of the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone may be 10 μmol / g or more but less than 70 μmol / g, 15 μmol / g or more but less than 65 μmol / g, or 20 μmol / g or more but less than 65 μmol / g.

[0045] The amount of hydroxyl groups and / or salts thereof per gram of aromatic polysulfone is determined by the following measurement method. The amount of hydroxyl groups and / or salts thereof in the aromatic polysulfone means the total content of the hydroxyl groups and the salts of the hydroxyl groups.

[0046] <Measurement of the total amount of hydroxyl groups and their salts in aromatic polysulfone (μmol / g)> A predetermined amount of aromatic polysulfone is dissolved in dimethylformamide, and then an excess amount of p-toluenesulfonic acid is added. Next, using a potentiometric titrator, titration is performed with a 0.05 mol / L potassium hydroxide / toluene-methanol solution to neutralize the remaining p-toluenesulfonic acid, and then the hydroxyl groups are neutralized. The amount (mol) of potassium methoxide required to neutralize the hydroxyl groups is divided by the predetermined amount (g) of aromatic polysulfone to determine the total amount of hydroxyl groups and their salts.

[0047] The weight average molecular weight (Mw) of the aromatic polysulfone according to the embodiment is preferably 30,000 or more and 70,000 or less, and may be 31,000 or more and 68,000 or less, or may be 32,000 or more and 66,000 or less. When the aromatic polysulfone has a weight average molecular weight within this range, the cured product of a resin composition containing the aromatic polysulfone and an epoxy resin can exhibit superior heat resistance.

[0048] The polydispersity (Mw / Mn) of the aromatic polysulfone is not particularly limited, but may be 1.0 to 4.0, 1.0 to 3.0, or 1.0 to 2.5.

[0049] The Mw and Mn of the aromatic polysulfone can be measured by the following method.

[0050] <Measurement of Mw and Mn of Aromatic Polysulfone, Calculation of Mw / Mn> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity (Mw / Mn) of aromatic polysulfone are determined by GPC measurement under the following [Measurement Conditions]. Mn and Mw are each measured twice, and the average values ​​are calculated as Mn and Mw, respectively, to calculate the average value of Mw / Mn.

[0051] [Measurement Conditions] Sample: 0.002 g of aromatic polysulfone was mixed with 1 mL of N,N-dimethylformamide solution containing 10 mM lithium bromide. Sample injection volume: 100 μL. Column (stationary phase): Two Tosoh Corporation "TSKgel GMHHR-H" (7.8 mmφ x 300 mm) columns connected in series. Column temperature: 40°C. Eluent (mobile phase): N,N-dimethylformamide containing 10 mM lithium bromide. Eluent flow rate: 0.8 mL / min. Detector: Differential refractometer (RI) + light scattering photometer (LS). dn / dc: Calculated from the peak area, injection concentration, and dn / dc (0.159) of a standard polystyrene with a known dn / dc value, as well as the peak area and injection concentration of the sample. Molecular weight calculation method: Absolute molecular weight was calculated using the light scattering photometer (LS).

[0052] The aromatic polysulfone of the embodiment has the repeating unit (1), and therefore can exhibit a high glass transition temperature (Tg) and excellent heat resistance.

[0053] The Tg of the aromatic polysulfone may be 230° C. or higher, 235° C. or higher, or 240° C. or higher. The upper limit of the Tg of the aromatic polysulfone is not particularly limited, and may be, for example, 260° C. or lower, 255° C. or lower, or 253° C. or lower. The upper and lower limits of the glass transition temperature can be arbitrarily combined, and the Tg of the aromatic polysulfone may be, for example, 230° C. or higher and 260° C. or lower, 235° C. or higher and 255° C. or lower, or 240° C. or higher and 253° C. or lower.

[0054] The glass transition temperature (Tg) of the aromatic polysulfone can be measured by the following method.

[0055] <Measurement of Glass Transition Temperature (Tg) of Aromatic Polysulfone> Using a differential scanning calorimeter (e.g., DSC-50 manufactured by Shimadzu Corporation), the glass transition temperature of the aromatic polysulfone is calculated according to a method in accordance with JIS K 7121. Approximately 10 mg of aromatic polysulfone is weighed, heated to 400°C at a heating rate of 10°C / min, cooled to 50°C, and then heated again to 400°C at a heating rate of 10°C / min. In the DSC chart obtained in the second heating, the glass transition temperature (Tg) of the aromatic polysulfone is calculated from the intersection of the step change partial curve and a straight line equidistant in the vertical direction from the two extended baseline lines (midpoint glass transition temperature).

[0056] Among the above, a preferred aromatic polysulfone of the embodiment is an aromatic polysulfone having a repeating unit (1) and a repeating unit (2), wherein in the repeating unit (1), R １ and R ２ is a methyl group, and in the repeating unit (2), m and n are 0, the number of repeating units (2) is 55% or more relative to 100% of the total number of all repeating units constituting the aromatic polysulfone, and more preferably, the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone is less than 70 μmol / g, or the weight average molecular weight (Mw) is 30,000 or more and 70,000 or less.

[0057] The aromatic polysulfone of the embodiment has the following aspects: "1" An aromatic polysulfone having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), wherein, relative to 100% of the total number of all repeating units constituting the aromatic polysulfone, the number of repeating units represented by formula (1) is preferably 2% to 45% inclusive, more preferably 5% to 40% inclusive, and even more preferably 5% to 35% inclusive, and the number of repeating units represented by formula (2) is preferably 55% to 98% inclusive, more preferably 60% to 95% inclusive, and even more preferably 65% ​​to 95% inclusive.

[0058] [In formula (1), R １ and R ２ each independently represents an alkyl group.

[0059] [In formula (2), R ３ and R ４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and m and n each independently represent an integer of 0 to 4. ３ or R ４ When there are multiple, they may be the same or different.

[0060] "2" The R １ and the R ２ is a methyl group. "3" The aromatic polysulfone according to "1" or "2" above, wherein the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone is preferably less than 70 μmol / g, more preferably 65 μmol / g or less, and even more preferably less than 65 μmol / g. "4" The aromatic polysulfone according to any one of "1" to "3" above, wherein the weight average molecular weight is preferably 30,000 or more and 70,000 or less, more preferably 31,000 or more and 68,000 or less, and even more preferably 32,000 or more and 66,000 or less.

[0061] [5] The aromatic polysulfone according to any one of [1] to [4] above, wherein the glass transition temperature (Tg) is preferably 230°C or higher, more preferably 235°C or higher, and even more preferably 240°C or higher.

[0062] <<Method for Producing Aromatic Polysulfone>> The method for producing aromatic polysulfone of the present embodiment includes a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain aromatic polysulfone, wherein the dihydroxy compound includes a compound represented by the following formula (1a) and a compound represented by the following formula (2a), and the dihalogeno compound includes a compound represented by the following formula (2b).

[0063] [In formula (1a), R １１ and R １２ each independently represents an alkyl group.

[0064] In the formula (1a), R １１ is the R in the formula (1). １ is synonymous with R １２ is the R in the formula (1). ２ An example of the dihydroxy compound represented by the formula (1a) is 9,9-bis(4-hydroxy-3-methylphenyl)fluorene.

[0065] [In formula (2a), R １３ and R １４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and p and q each independently represent an integer of 0 to 4. １３ or R １４ When there are a plurality of p and q, they may be the same or different. It is preferable that p and q are each 0.

[0066] In the formula (2a), R １３ is the R in the formula (2). ３ is synonymous with R １４ is the R in the formula (2). ４An example of the dihydroxy compound represented by the formula (2a) is dihydroxydiphenyl sulfone.

[0067] [In formula (2b), X １ and X ２ each independently represents a halogen atom. １ and X ２ may be the same or different. １５ and R １６ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and r and s each independently represent an integer of 0 to 4. １５ or R １６ When there are a plurality of r and s, they may be the same or different. It is preferable that each of r and s is 0.]

[0068] In the formula (2b), X １ and X ２ Examples of the halogen atom in R include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferred. １５ is the R in the formula (2). ３ is synonymous with R １６ is the R in the formula (2). ４ An example of the dihalogeno compound represented by the formula (2b) is dihalogenodiphenyl sulfone.

[0069] In the method for producing an aromatic polysulfone according to the embodiment, in the polymerization step, the dihydroxy compound preferably includes dihydroxydiphenyl sulfone and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the dihalogeno compound preferably includes dihalogenodiphenyl sulfone.

[0070] A preferred embodiment of the method for producing aromatic polysulfone includes a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain aromatic polysulfone, wherein the dihydroxy compound includes a compound represented by formula (1a) and a compound represented by formula (2a), the dihalogeno compound includes a compound represented by formula (2b), and the total amount of the compound represented by formula (1a), the compound represented by formula (2a), and the compound represented by formula (2b) may be 90 mol % or more relative to all monomers (100 mol %) used in the polymerization of the aromatic polysulfone.

[0071] A particularly preferred embodiment of the method for producing an aromatic polysulfone may be a method comprising a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain an aromatic polysulfone, wherein the dihydroxy compound comprises a compound represented by formula (1a) and a compound represented by formula (2a), and the dihalogeno compound comprises a compound represented by formula (2b).

[0072] In the method for producing an aromatic polysulfone according to the embodiment, it is preferable that in the polymerization step, the molar ratio of the dihydroxy compound to the dihalogeno compound satisfies the condition of the following formula (II).

[0073] The dihydroxy compound / the dihalogeno compound≦1 Formula (II)

[0074] By satisfying the condition of the formula (II), i.e., by making the value of the molar ratio 1 or less, it is possible to easily produce an aromatic polysulfone in which the number of repeating units represented by the formula (2) is 55% or more relative to 100% of the total number of all repeating units constituting the aromatic polysulfone.

[0075] As shown in formula (II), the value of the dihydroxy compound / dihalogeno compound is 1 or less, may be 0.95 or more and 1 or less, or may be 0.96 or more and 1 or less.

[0076] With respect to the dihydroxy compounds in the polymerization step, the proportion of the compound represented by formula (1a) relative to the total amount (100 mol%) of the dihydroxy compounds may be 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less. In particular, when the proportion of the compound represented by formula (1a) relative to the total amount (100 mol%) of the dihydroxy compounds is less than 90 mol%, an aromatic polysulfone having 55% or more of the repeating unit (2) relative to the total number (100%) of all repeating units constituting the aromatic polysulfone can be easily produced.

[0077] The ratio of the compound represented by formula (1a) to the total amount (100 mol%) of the dihydroxy compound may be, for example, 5 mol% or more and 80 mol% or less, 20 mol% or more and 75 mol% or less, 30 mol% or more and 70 mol% or less, or 50 mol% or more and 65 mol% or less.

[0078] In this production method, the condition of formula (II) above, i.e., the condition that the ratio of the dihydroxy compound / the dihalogeno compound is ≦1, is satisfied, and further, the ratio of the compound represented by formula (1a) to the total amount (100 mol %) of the dihydroxy compounds is within the above range, so that an aromatic polysulfone having 55% or more of the repeating unit (2) relative to the total number (100 mol %) of all repeating units constituting the aromatic polysulfone can be more easily produced.

[0079] Furthermore, an aromatic polysulfone having the repeating unit (3) exemplified above in addition to the repeating unit (1) and the repeating unit (2) can be produced by including, as dihydroxy compounds, the compound represented by the formula (1a) and the compound represented by the formula (2a), as dihalogeno compounds, the compound represented by the formula (2b), and as dihydroxy compounds, the compound represented by the following formula (5):

[0080] (5) HO-Ph ３ -R-Ph ４ -OH [wherein, Ph ３ , Ph ４ and R has the same meaning as defined above.]

[0081] Furthermore, an aromatic polysulfone having the repeating unit (4) exemplified above in addition to the repeating unit (1) and the repeating unit (2) can be produced by including, as dihydroxy compounds, the compound represented by the formula (1a) and the compound represented by the formula (2a), as dihalogeno compounds, the compound represented by the formula (2b), and as dihydroxy compounds, the compound represented by the following formula (6):

[0082] (6) HO-(Ph ５ ) ｔ -OH [wherein, Ph ５ and t have the same meanings as defined above.]

[0083] The OH groups in the above formulae (1a), (2a) and (5) to (6) may correspond to hydroxyl groups and salts thereof which may be located at the main chain terminals of the aromatic polysulfone.

[0084] The polycondensation of aromatic polysulfone is preferably carried out in a solvent using an alkali metal carbonate. The alkali metal carbonate may be a carbonate, which is a normal salt, a bicarbonate (hydrogen carbonate), which is an acidic salt, or a mixture of the two. As the carbonate, sodium carbonate or potassium carbonate is preferably used, and as the hydrogen carbonate, sodium bicarbonate or potassium bicarbonate is preferably used.

[0085] As the solvent for polycondensation, an organic polar solvent is preferably used, specific examples of which include dimethyl sulfoxide, 1-methyl-2-pyrrolidone, sulfolane (1,1-dioxothiane), 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, dimethyl sulfone, diethyl sulfone, diisopropyl sulfone, and diphenyl sulfone.

[0086] The method for producing an aromatic polysulfone according to an embodiment has the following aspects: "11" The method for producing an aromatic polysulfone according to any one of "1" to "5" above, comprising a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain an aromatic polysulfone, wherein the dihydroxy compound includes a compound represented by the following formula (1a) and a compound represented by the following formula (2a), and the dihalogeno compound includes a compound represented by the following formula (2b).

[0087] [In formula (1a), R １１ and R １２ each independently represents an alkyl group.

[0088] [In formula (2a), R １３ and R １４ R each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and p and q each independently represent an integer of 0 to 4. １３ or R １４ When there are multiple, they may be the same or different.

[0089] [In formula (2b), X １ and X ２ each independently represents a halogen atom. １ and X ２ may be the same or different. １５ and R １６ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and r and s each independently represent an integer of 0 to 4. １５ or R １６ When there are multiple, they may be the same or different.

[0090]

[12] The method for producing an aromatic polysulfone according to

[11] above, wherein in the polymerization step, the dihydroxy compound includes dihydroxydiphenyl sulfone and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the dihalogeno compound includes dihalogenodiphenyl sulfone.

[0091] <Resin Composition> The resin composition of the embodiment contains an aromatic polysulfone and an epoxy resin. Examples of the aromatic polysulfone in the resin composition include the same aromatic polysulfone as the aromatic polysulfone of the above embodiment. As an example, the resin composition of the embodiment may contain the aromatic polysulfone described in any one of <1> to <4> above and an epoxy resin.

[0092] The content of the aromatic polysulfone in the resin composition of the embodiment is preferably 1 to 70 parts by mass, more preferably 2 to 50 parts by mass, even more preferably 4 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, relative to 100 parts by mass of the total of the epoxy resin and the aromatic polysulfone. Alternatively, the content of the aromatic polysulfone in the resin composition of the embodiment is preferably 2 to 25% by mass, more preferably 5 to 20% by mass, and even more preferably 10 to 15% by mass, relative to 100% by mass of the total mass of the resin composition.

[0093] <Epoxy Resin> In this specification, the term "epoxy resin" refers to a compound having at least one epoxy group in the molecule. Examples of the epoxy resin include glycidyl ether type epoxy compounds obtained by reacting epichlorohydrin with polyhydric phenols such as bisphenol A, bisphenol F, bisphenol S, hexahydrobisphenol A, tetramethylbisphenol A, resorcinol, cresol novolak, tetrabromobisphenol A, trihydroxybiphenyl, bisresorcinol, bisphenol hexafluoroacetone, tetramethylbisphenol F, bixylenol, and dihydroxynaphthalene; alicyclic glycidyl ether type epoxy compounds obtained by hydrogenating the glycidyl ether type epoxy compounds; polyglycidyl ether type epoxy compounds obtained by reacting epichlorohydrin with aliphatic polyhydric alcohols such as glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, and polypropylene glycol; and glycidyl ester type epoxy compounds obtained by reacting epichlorohydrin with hydroxycarboxylic acids such as p-hydroxybenzoic acid and β-hydroxynaphthoic acid. Examples of the epoxy resin include polyglycidyl ester epoxy compounds derived from polycarboxylic acids such as phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, and polymerized fatty acids; glycidyl aminoglycidyl ether epoxy compounds derived from aminophenols, aminoalkylphenols, and the like; glycidyl aminoglycidyl ester epoxy compounds derived from aminobenzoic acid; and flexible epoxy resins whose skeletons are polyether, polyurethane, polycarbonate, polyester, polyacrylic, silicone, and the like. One type of epoxy resin may be used, or two or more types may be used in combination.

[0094] The number of epoxy groups per molecule of the epoxy resin is not particularly limited, and the epoxy resin may be a compound having two epoxy groups in the molecule (bifunctional epoxy resin), or may be a compound having three or more epoxy groups in the molecule (polyfunctional epoxy resin).

[0095] The epoxy resin is preferably a liquid epoxy resin, which means an epoxy resin that is in a liquid state at 50° C. (at atmospheric pressure).

[0096] The content of the epoxy resin in the resin composition of the embodiment is preferably 30 to 99 parts by mass, more preferably 50 to 98 parts by mass, even more preferably 70 to 96 parts by mass, and particularly preferably 80 to 95 parts by mass, relative to 100 parts by mass of the total of the epoxy resin and aromatic polysulfone. Alternatively, the content of the epoxy resin in the resin composition of the embodiment is more preferably 40 to 75% by mass, even more preferably 50 to 70% by mass, and particularly preferably 55 to 65% by mass, relative to 100% by mass of the total mass of the resin composition.

[0097] <Curing Agent> The resin composition of this embodiment may further contain a curing agent. The curing agent according to this embodiment is not particularly limited as long as it is capable of reacting with the epoxy resin. Examples of the curing agent include compounds typically used as curing agents for epoxy resins, and amine-based curing agents are preferably used. Examples of such curing agents include tetramethylguanidine, imidazole or a derivative thereof, carboxylic acid hydrazides, tertiary amines, aromatic amines, aliphatic amines, dicyandiamide or a derivative thereof, and the like. The aromatic amine is preferably diaminodiphenylmethane, bis(4-aminophenyl)sulfone, or a derivative thereof. One type of aromatic amine may be used alone, or two or more types may be used in combination.

[0098] In this specification, the term "derivative" refers to a compound in which the basic skeleton remains unchanged and a small part of the compound is substituted with another atom or atomic group.

[0099] One type of curing agent may be used, or two or more types may be used in combination. The content of the curing agent in the resin composition is preferably 0.5 to 1.5 equivalents per equivalent of epoxy group in the epoxy resin. When the content is 0.5 equivalents or more, the resin is well cured and good mechanical properties are easily exhibited. When the content is 1.5 equivalents or less, unreacted curing agent is less likely to remain, making it easier to obtain good mechanical properties. The amount of curing agent added is not particularly limited, but is preferably 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resin.

[0100] <Other Components> The resin composition of this embodiment may optionally contain other components that do not fall under any of the above-mentioned aromatic polysulfones, epoxy resins, and curing agents. Examples of other components include solvents, resins that do not fall under the category of aromatic polysulfones or epoxy resins, coloring components, lubricants, various surfactants, antioxidants, heat stabilizers, various other stabilizers, UV absorbers, antistatic agents, etc. The content of other components is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 0% by mass or more but less than 5% by mass, relative to the total mass of the resin composition of this embodiment.

[0101] Solvent The resin composition of the present embodiment may further contain a solvent. However, from the viewpoint of reducing the amount of solvent remaining in a cured product obtained by curing the resin composition containing the aromatic polysulfone of the present embodiment, it is preferable that the amount of solvent contained in the resin composition is small.

[0102] The solvent may be an organic solvent, and the organic solvent may be a polar solvent or an aprotic polar solvent.

[0103] The solvent used is preferably one that has the effect of improving the affinity of the aromatic polysulfone with the epoxy resin, and examples of the solvent include aprotic polar solvents such as N-ethylpyrrolidone, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, and sulfolane.

[0104] The resin composition of the present embodiment preferably contains 0 to 5 parts by mass, more preferably 0 to 1 part by mass, of the solvent relative to 100 parts by mass of the epoxy resin and the aromatic polysulfone combined, and even more preferably contains substantially no solvent. The solvent content may be 0 to 5% by mass, 0 to 1% by mass, or 0 to 0.1% by mass, relative to the total mass of the resin composition of the present embodiment, and preferably contains substantially no solvent.

[0105] Other Resins The resin composition of this embodiment may further contain other resins that do not fall under either the aromatic polysulfone or the epoxy resin. Examples of other resins include polyamide, polyester, polyphenylene sulfide, polycarbonate, polyphenylene ether, aromatic polyketone, polyetherimide, phenolic resin, polyimide resin, and modified products thereof. The content of the other resin is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and even more preferably 0 to 1 part by mass, relative to the total mass of the resin composition. The resin composition may not substantially contain other resins.

[0106] According to the resin composition of the embodiment described above, it is possible to provide various molded articles having improved glass transition temperatures (tan δ) measured by dynamic mechanical analysis (DMA) and good heat resistance.

[0107] The resin composition of the embodiment has the following aspects: "21" A resin composition comprising the aromatic polysulfone according to any one of "1" to "5" above and an epoxy resin. "22" The resin composition according to "21" above, further comprising a curing agent.

[0108] <<Cured Product>> The cured product of this embodiment is obtained by curing the resin composition of the above-described embodiment. For example, by heating the resin composition of this embodiment containing a curing agent to a temperature higher than 150°C and not higher than 200°C to cure it, a cured product of any shape and form can be easily produced.

[0109] When curing the resin composition, it is preferable to cure a composition in which the aromatic polysulfone is dissolved in the epoxy resin, or the epoxy resin and the aromatic polysulfone are compatible with each other, and the epoxy resin and the aromatic polysulfone are uniformly mixed.

[0110] The cured product of this embodiment uses the resin composition of the above-described embodiment, and therefore has an improved glass transition temperature (tan δ) measured by dynamic mechanical analysis (DMA) and heat resistance.

[0111] <Prepreg> The prepreg of this embodiment includes the resin composition described above and reinforcing fibers. The prepreg of this embodiment may be obtained by impregnating reinforcing fibers with the resin composition described above. From the viewpoint of the strength of the prepreg, the reinforcing fibers are preferably at least one selected from the group consisting of carbon fibers, glass fibers, boron fibers, and aramid fibers. Furthermore, from the viewpoints of mechanical properties and light weight, carbon fibers are more preferable. These reinforcing fibers may be in the form of a woven fabric or a nonwoven fabric.

[0112] The method for producing the prepreg of this embodiment is not particularly limited, and may be, for example, by impregnating the reinforcing fibers with the resin composition described above. Examples of the method for impregnating the reinforcing fibers with the resin composition include a wet method and a hot melt method (dry method).

[0113] The wet method is a method in which reinforcing fibers are immersed in a resin composition, then pulled out, and the solvent is evaporated from the reinforcing fibers using an oven or the like, thereby impregnating the reinforcing fibers with the resin composition.

[0114] The hot melt method is a method in which a resin composition whose viscosity has been reduced by heating is directly impregnated into reinforcing fibers. Another form of the hot melt method is a method in which a film coated with the resin composition is prepared on a release paper or the like, and then the film is placed on both sides or one side of the reinforcing fibers, and the resin composition is impregnated into the reinforcing fibers by heating and pressurizing.

[0115] After impregnating the reinforcing fibers with the resin composition in this manner, the prepreg can be produced by curing the impregnated resin composition by heating, for example, to 120 to 150° C. The impregnated resin composition may be semi-cured.

[0116] As used herein, the term "semi-cured" refers to a state in which the viscosity or hardness of a resin has increased to the point where a certain shape can be maintained, and the viscosity or hardness can be increased further from this state.

[0117] The prepreg of the embodiment has the following aspects: "31" A prepreg comprising the resin composition according to the above "22" and reinforcing fibers. "32" The prepreg according to the above "31", in which the reinforcing fibers are carbon fibers.

[0118] As one embodiment of the present invention, a cured product obtained by curing the above-described prepreg is provided. The prepreg of this embodiment uses the resin composition of the embodiment, and therefore, it is possible to provide a cured prepreg having an improved glass transition temperature (tan δ) measured by dynamic mechanical analysis (DMA) and good heat resistance.

[0119] In another embodiment of the present invention, there is provided a product formed by laminating a plurality of the prepregs described above. Specifically, the product formed by laminating a plurality of the prepregs described above can be obtained by stacking a plurality of the prepregs produced by the above method and thermosetting and molding them using an autoclave or a heat press machine.

[0120] Examples of prepreg lamination patterns include laminating prepregs with the reinforcing fibers contained in the prepregs aligned in the same direction (0°), and laminating prepregs while shifting them at any angle. For example, when shifting by 45°, the lamination angles are 0° / 45° / 90° / 135° / 180° / 225° / 270° / 315° / 360° (0°). Note that "shifting at any angle" means changing the relative angle between the fiber directions contained in the two layers of prepregs to be laminated. The arbitrary angle can be set appropriately depending on the application of the molded body.

[0121] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0122] <Measurement of Mw and Mn of Aromatic Polysulfone, Calculation of Mw / Mn> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity (Mw / Mn) of the aromatic polysulfone were determined by GPC measurement under the following [Measurement Conditions]. Mw and Mn were each measured twice, and the average values ​​were calculated as Mw and Mn, respectively, to determine the average value of Mw / Mn.

[0123] [Measurement Conditions] Sample: 0.002 g of aromatic polysulfone was mixed with 1 mL of N,N-dimethylformamide solution containing 10 mM lithium bromide. Sample injection volume: 100 μL. Column (stationary phase): Two Tosoh Corporation "TSKgel GMHHR-H" (7.8 mmφ x 300 mm) columns connected in series. Column temperature: 40°C. Eluent (mobile phase): N,N-dimethylformamide containing 10 mM lithium bromide. Eluent flow rate: 0.8 mL / min. Detector: Differential refractometer (RI) + light scattering photometer (LS). dn / dc: Calculated from the peak area, injection concentration, and dn / dc (0.159) of a standard polystyrene with a known dn / dc value, and the peak area and injection concentration of the sample. Molecular weight calculation method: Absolute molecular weight was calculated using the light scattering photometer (LS).

[0124] <Measurement of Glass Transition Temperature (Tg) of Aromatic Polysulfone> Using a differential scanning calorimeter (DSC-50 manufactured by Shimadzu Corporation), the glass transition temperature (Tg) of the aromatic polysulfone was calculated according to JIS-K7121. Approximately 10 mg of aromatic polysulfone was weighed, heated to 400°C at a heating rate of 10°C / min, cooled to 50°C, and then heated again to 400°C at a heating rate of 10°C / min. In the DSC chart obtained in the second heating, the glass transition temperature (Tg) of the aromatic polysulfone was calculated from the intersection (midpoint glass transition temperature) of the stepwise change partial curve and a straight line equidistant in the vertical direction from the two baseline extensions.

[0125] <Measurement of the total amount of hydroxyl groups and their salts in aromatic polysulfone (μmol / g)> A predetermined amount of aromatic polysulfone was dissolved in dimethylformamide, and then an excess amount of p-toluenesulfonic acid was added. Next, using a potentiometric titrator, the solution was titrated with a 0.05 mol / L potassium hydroxide / toluene-methanol solution to neutralize the remaining p-toluenesulfonic acid, and then the hydroxyl groups were neutralized. The amount (mol) of potassium methoxide required to neutralize the hydroxyl groups was divided by the predetermined amount (g) of aromatic polysulfone to determine the total amount of hydroxyl groups and their salts.

[0126] <Evaluation of Solubility of Aromatic Polysulfone in Epoxy Resin> The properties of the epoxy resin compositions obtained by the method described below were visually inspected, and the solubility of the aromatic polysulfone in the epoxy resin was evaluated according to the following criteria. A: No significant turbidity was observed in the epoxy resin composition, and the solubility of the aromatic polysulfone in the epoxy resin was very good. B: Some turbidity was observed in the epoxy resin composition, and the solubility of the aromatic polysulfone in the epoxy resin was somewhat poor. F: A uniform epoxy resin composition was not obtained, and the solubility of the aromatic polysulfone in the epoxy resin was poor. In addition, a cured product of the epoxy resin composition could not be obtained.

[0127] <Glass Transition Temperature (tan δ) of Cured Product of Epoxy Resin Composition> A cured product of an epoxy resin composition obtained by the method described below was used as a measurement sample, and the glass transition temperature (°C) of the cured product was measured by dynamic mechanical analysis (DMA). Specifically, the glass transition temperature was determined from the peak top temperature (°C) of tan δ measured under the following conditions using a dynamic viscoelasticity measuring device (Q800, manufactured by TA Instruments Co., Ltd.).

[0128] [Measuring conditions for tan δ] Measurement mode: bending mode Amplitude: 20 μm Frequency: 10 Hz Heating rate: 5° C. / min

[0129] <Production of Aromatic Polysulfone> Example 1 In a polymerization vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser with a receiver attached to its tip, 220.55 g of dichlorodiphenyl sulfone (DCDPS), 80.09 g of dihydroxydiphenyl sulfone (DHDPS), 181.67 g of 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (BHMPF), 116.10 g of potassium carbonate, and 443 g of N-methyl-2-pyrrolidone (NMP) were mixed and reacted at 190°C for 10 hours. The resulting reaction mixture was then diluted with NMP and cooled to room temperature to precipitate unreacted potassium carbonate and by-product potassium chloride. The above solution was added dropwise to water to precipitate aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate. The resulting precipitate was thoroughly washed repeatedly with water and dried by heating at 150° C., thereby obtaining the aromatic polysulfone of Example 1.

[0130] Table 1 shows the molar ratios of the dihydroxy monomers (DHDPS and BHMPF) and the dichloro monomer (DCDPS) used in the polymerization of aromatic polysulfone. Table 1 also shows the proportion (mol%) of the bisphenol fluorene monomer (BHMPF) relative to 100 mol% of the total amount of the dihydroxy monomers (DHDPS and BHMPF) used in the polymerization of aromatic polysulfone.

[0131] Examples 2 and 3 In Example 1, the molar ratio of the dihydroxy monomers (DHDPS and BHMPF) and the dichloro monomer (DCDPS) used in the polymerization of the aromatic polysulfone was changed to the value shown in Table 1. Furthermore, the proportion (mol%) of the bisphenol fluorene monomer (BHMPF) relative to the total amount (100 mol%) of the dihydroxy monomers (DHDPS and BHMPF) used in the polymerization of the aromatic polysulfone was changed to the value shown in Table 1. The aromatic polysulfones of each Example were obtained in the same manner as in Example 1.

[0132] Comparative Example 1 An aromatic polysulfone of Comparative Example 1 was obtained in the same manner as in Example 1, except that dihydroxydiphenyl sulfone (DHDPS) was not used, and only bisphenol fluorene monomer (BHMPF) was used as the dihydroxy monomer used in the polymerization of the aromatic polysulfone, and the molar ratio of bisphenol fluorene monomer (BHMPF) to dichloromonomer (DCDPS) was changed to the value shown in Table 1.

[0133] Comparative Example 2 An aromatic polysulfone of Comparative Example 2 was obtained in the same manner as in Example 1, except that 9,9-bis(4-hydroxyphenyl)fluorene (BHPF) was used instead of 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (BHMPF) used in the polymerization of the aromatic polysulfone in Example 1.

[0134] The weight average molecular weight (Mw), polydispersity (Mw / Mn), Tg, and total amount of hydroxyl groups and their salts (referred to as the hydroxyl group amount in Table 1) of the aromatic polysulfones obtained in each Example and Comparative Example are shown in Table 1.

[0135] <Production of Cured Epoxy Resin Composition> <Cured Products of Examples 1 to 3 and Comparative Examples 1 and 2> 20 g of any of the aromatic polysulfones obtained in the above Examples and Comparative Examples and 100 g of an epoxy resin (Sumiepoxy ELM-100, manufactured by Sumitomo Chemical) were placed in a 500 mL separable flask and stirred at 130°C for 1 hour. The flask was then cooled to 100°C, and 45 g of bis(4-aminophenyl)sulfone (manufactured by Aldrich Japan) was added. The mixture was stirred at 140°C for 1 hour to obtain an epoxy resin composition. The obtained epoxy resin composition was filled into a 3 mm thick metal frame and then heat-cured at 180°C for 2 hours using a high-temperature hot air dryer to obtain cured products of the epoxy resin compositions of Examples 1 to 3 and Comparative Examples 1 and 2.

[0136] <<Cured Product of Comparative Example 3>> A cured product of the epoxy resin composition of Comparative Example 3 was obtained by the same procedure as in the production of the cured product of the epoxy resin composition of Example 1 etc., except that the aromatic polysulfone was not added.

[0137] The glass transition temperature (tan δ) of the cured product of the epoxy resin composition obtained above was measured, and the value is shown in Table 1.

[0138]

[0139] The aromatic polysulfones of Examples 1 to 3 had superior solubility in epoxy resins compared to the aromatic polysulfones of Comparative Examples 1 and 2. This indicates that aromatic polysulfones in which the number of repeating units represented by formula (2) is 55% or more relative to the total number of all repeating units constituting the aromatic polysulfone (100%) have excellent solubility in epoxy resins.

[0140] Furthermore, the aromatic polysulfones of Examples 1 to 3, which used 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (BHMPF) as a monomer, had better solubility in epoxy resins than Comparative Example 2, which used 9,9-bis(4-hydroxyphenyl)fluorene (BHPF). This suggests that the R １ and the R ２ It was shown that aromatic polysulfones in which the alkyl group is present can exhibit superior solubility in epoxy resins.

[0141] Furthermore, the cured products of the epoxy resin compositions of Examples 2 and 3 had higher glass transition temperatures (tan δ) and better heat resistance than the cured product of the epoxy resin composition of Example 1. This demonstrates that cured products of epoxy resin compositions containing aromatic polysulfones having an amount of hydroxyl groups and / or salts thereof measured above of less than 70 μmol, or aromatic polysulfones having a weight-average molecular weight of 30,000 or more and 70,000 or less, have better heat resistance.

[0142] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to each embodiment, but is limited only by the scope of the claims.

Claims

1. An aromatic polysulfone having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), wherein the number of repeating units represented by the formula (2) is 55% or more relative to the total number of all repeating units constituting the aromatic polysulfone (100%). [In formula (1), R １ and R ２ each independently represents an alkyl group. [In formula (2), R ３ and R ４ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and each of m and n independently represents an integer of 0 to 4. ３ Or R ４ When there are multiple, they may be the same or different.

2. The above R １ and the R ２ The aromatic polysulfone according to claim 1 , wherein is a methyl group.

3. The aromatic polysulfone according to claim 1 or 2, wherein the amount of hydroxyl groups and / or salts thereof per 1 g of the aromatic polysulfone is less than 70 μmol / g.

4. The aromatic polysulfone according to claim 1 or 2, having a weight average molecular weight of 30,000 or more and 70,000 or less.

5. A method for producing an aromatic polysulfone, comprising a polymerization step of polymerizing a dihydroxy compound and a dihalogeno compound to obtain an aromatic polysulfone, wherein the dihydroxy compound comprises a compound represented by the following formula (1a) and a compound represented by the following formula (2a), and the dihalogeno compound comprises a compound represented by the following formula (2b). [In formula (1a), R １１ and R １２ each independently represents an alkyl group. [In formula (2a), R １３ and R １４ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and p and q each independently represent an integer of 0 to 4. １３ Or R １４ When there are multiple, they may be the same or different. [In formula (2b), X １ and X ２ Each of X independently represents a halogen atom. １ and X ２ may be the same or different. １５ and R １６ each independently represents a halogen atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and r and s each independently represent an integer of 0 to 4. １５ Or R １６ When there are multiple, they may be the same or different.

6. The method for producing aromatic polysulfone according to claim 5, wherein in the polymerization step, the dihydroxy compound includes dihydroxydiphenylsulfone and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the dihalogeno compound includes dihalogenodiphenylsulfone.

7. The method for producing an aromatic polysulfone according to claim 5, wherein in the polymerization step, the molar ratio of the dihydroxy compound to the dihalogeno compound satisfies the condition of the following formula (II): dihydroxy compound / dihalogeno compound≦1 Formula (II) 8. A resin composition comprising the aromatic polysulfone according to claim 1 or 2 and an epoxy resin.

9. The resin composition according to claim 8, further comprising a curing agent.

10. A prepreg comprising the resin composition according to claim 9 and reinforcing fibers.

11. The prepreg of claim 10, wherein the reinforcing fibers are carbon fibers.

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