Polyfluorene, curable resin composition, and cured product

Abstract

To provide a polyfluorene that yields a cured product with excellent dielectric properties and flame retardancy. [Solution] The polyfluorene according to the embodiment has vinylbenzylfluorene units as constituent units, and 80 mol% or more of the total constituent units are fluorene units. The polyfluorene may also have alkylfluorene units as fluorene units in addition to vinylbenzylfluorene units.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to polyfluorene, a curable resin composition containing the polyfluorene, and a cured product obtained by curing these. [Background technology]

[0002] Polyfluorene is attracting attention as a functional polymer material and is suitably used in electrical and electronic components such as organic EL displays, polymer conductors, and printed circuit boards.

[0003] For example, Patent Document 1 discloses a polyfluorene having a substituted fluorene ring with an alkyl substituent at the 9-position as a repeating structural unit, with an unsubstituted fluorene ring at the terminal. Patent Document 2 discloses a copolymer containing 10 to 90% by mass of dioctylfluorene units and 10 to 90% by mass of structural units derived from amine-containing monomers.

[0004] Patent Document 3 discloses a compound having a structure in which vinylbenzylfluorene units, in which the benzene ring of fluorene may be substituted with a benzyl group, and constituent units derived from 1,4-benzenedimethanol are alternately repeated. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-155131 [Patent Document 2] Japanese Patent Publication No. 2009-256679 [Patent Document 3] Patent No. 7602311 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] For example, in curable resins used in electrical and electronic components, excellent dielectric properties are required due to a low dielectric loss tangent, as well as flame retardancy to ensure safety. The compound described in Patent Document 3 yields a curable resin by having vinylbenzylfluorene units as constituent units. However, because it has a structure in which vinylbenzylfluorene units and constituent units derived from 1,4-benzenedimethanol are alternately repeated, the proportion of fluorene units to the total constituent units is low.

[0007] Embodiments of the present invention aim to provide a polyfluorene that yields a cured product having excellent dielectric properties and flame retardancy, and a curable resin composition containing the polyfluorene. [Means for solving the problem]

[0008] The present invention includes embodiments shown below. [1] Polyfluorene having vinylbenzylfluorene units as constituent units, wherein 80 mol% or more of the total constituent units are fluorene units. [2] The polyfluorene according to [1], wherein the fluorene unit is an alkylfluorene unit together with the vinylbenzylfluorene unit.

[0009] [3] The vinylbenzylfluorene unit has a constituent unit (1) represented by the following general formula (1), [ka] R in general formula (1) 1 R represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (3), 2 , R 3 and R 4 Each of the following independently represents a hydrocarbon group with 1 to 5 carbon atoms, a and b independently represent integers from 0 to 3, and c represents an integer from 0 to 4. [ka] R in general formula (3)4 represents a hydrocarbon group having 1 to 5 carbon atoms, c represents an integer of 0 to 4, and * represents the bonding position to the fluorene ring. The polyfluorene according to [1] or [2].

[0010] [4] Having a structural unit (2) represented by the following general formula (2) together with the structural unit (1) as the fluorene unit.

Chemical formula

[0011] [5] The polyfluorene according to [4], wherein the structural unit (2) contains a structural unit (21) in which at least one of R 5 and R 6 in the general formula (2) represents an alkyl group having 1 to 22 carbon atoms. [6] The polyfluorene according to any one of [1] to [5], wherein the introduction rate of a substituted or unsubstituted vinylbenzyl group to the 9-position carbon atom of the fluorene unit is 5 to 60 mol%. [7] The polyfluorene according to any one of [1] to [6], wherein the introduction rate of an alkyl group to the 9-position carbon atom of the fluorene unit is 10 to 80 mol%. [8] The polyfluorene according to any one of [1] to [7], having a number average molecular weight of 1000 to 50000.

[0012] [9] A curable resin composition containing the polyfluorene according to any one of [1] to [8].

[10] A cured product obtained by curing the polyfluorene according to any one of [1] to [8]. [

[11] A cured product obtained by curing the curable resin composition according to [9]. [Effects of the Invention]

[0013] According to this embodiment, it is possible to provide a polyfluorene that yields a cured product having excellent dielectric properties and flame retardancy, and a curable resin composition containing the polyfluorene. [Modes for carrying out the invention]

[0014] The polyfluorene according to this embodiment is a polymer having vinylbenzylfluorene units as constituent units, with 80 mol% or more of the total constituent units being fluorene units. Having vinylbenzylfluorene units as constituent units, and with 80 mol% or more of the total constituent units being fluorene units, that is, consisting substantially only of fluorene units, results in a cured product with excellent dielectric properties and flame retardancy. Here, a constituent unit refers to an atomic group that makes up a polymer, and is also called a repeating unit.

[0015] A fluorene unit is a constituent unit of polyfluorene, having a substituted or unsubstituted fluorene ring. Polyfluorene may have only substituted fluorene units, or it may have both substituted and unsubstituted fluorene units. The proportion of fluorene units in the total constituent units of the polyfluorene according to this embodiment is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 100 mol%.

[0016] Furthermore, other constituent units that may be included together with fluorene units as constituent units of polyfluorene are not particularly limited. For example, from the viewpoint of dielectric properties, constituent units consisting of hydrocarbons that do not contain heteroatoms are preferred. Also, from the viewpoint of flame retardancy, constituent units consisting of aromatic hydrocarbons in which the aromatic ring is directly bonded to the fluorene unit (i.e., bonded without the interposition of methylene groups, etc.) are preferred. Specifically, examples include alkyl-substituted or unsubstituted benzene units and alkyl-substituted or unsubstituted naphthalene units.

[0017] The polyfluorene according to this embodiment has vinylbenzylfluorene units as at least a portion of the fluorene units. The vinylbenzylfluorene unit is a fluorene unit having a substituted or unsubstituted vinylbenzyl group (hereinafter sometimes simply referred to as "vinylbenzyl group"). The vinylbenzyl group is preferably introduced as a substituent on the carbon atom at position 9 of the fluorene unit, and only one of the two hydrogen atoms bonded to the carbon atom at position 9 may be substituted with the vinylbenzyl group, or both of the two hydrogen atoms may be substituted with the vinylbenzyl group.

[0018] In one embodiment, the polyfluorene may have alkylfluorene units as fluorene units. An alkylfluorene unit is a fluorene unit having an alkyl group as a substituent. By introducing an alkyl group to the fluorene unit, the solubility in organic solvents can be improved. The alkyl group is preferably introduced as a substituent on the carbon atom at position 9 of the fluorene unit, and only one of the two hydrogen atoms bonded to the carbon atom at position 9 may be substituted with the alkyl group, or both of the two hydrogen atoms may be substituted with the alkyl group.

[0019] In the alkylfluorene unit, the alkyl group may be linear or branched, and is preferably linear. The alkyl group preferably has 1 to 22 carbon atoms, more preferably 2 to 18, more preferably 3 to 12, and even more preferably 4 to 10 carbon atoms.

[0020] Furthermore, fluorene units having both a vinylbenzyl group and an alkyl group as substituents are considered to be vinylbenzylfluorene units, not alkylfluorene units.

[0021] Polyfluorene may have vinylbenzylfluorene units and alkylfluorene units as constituent units, or it may have unsubstituted fluorene units along with the vinylbenzylfluorene units and alkylfluorene units. The arrangement order of these constituent units may be regular or irregular (i.e., random). Preferably, it is a random copolymer (disordered copolymer) in which these constituent units are randomly arranged.

[0022] In polyfluorenes, it is preferable that the carbon atoms at positions 2 and 7 of the fluorene ring of a fluorene unit are bonded to a constituent unit adjacent to that fluorene unit.

[0023] In one embodiment, polyfluorene preferably has a constituent unit (1) represented by the following general formula (1) as a vinylbenzylfluorene unit. [ka]

[0024] In equation (1), R 1 R represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (3). 2 , R 3 and R 4 Each of the following independently represents a hydrocarbon group with 1 to 5 carbon atoms. A and B each independently represent an integer from 0 to 3. C represents an integer from 0 to 4.

[0025] [ka] In equation (3), R 4 * represents a hydrocarbon group with 1 to 5 carbon atoms. c represents an integer from 0 to 4. * represents the bond position to the fluorene ring in formula (1).

[0026] The group represented by formula (3) is a substituted or unsubstituted vinylbenzyl group. Therefore, R 1If the group is represented by formula (3), then the constituent unit (1) is a divinylbenzylfluorene unit having two vinylbenzyl groups as substituents.

[0027] R in equation (1) 1 Regarding this, the alkyl group may be linear or branched, and is preferably linear. The number of carbon atoms in the alkyl group is more preferably 2 to 18, more preferably 3 to 12, and even more preferably 4 to 10.

[0028] R in equation (1) 2 , R 3 and R 4 , and R in equation (3) 4 Each of these independently represents a hydrocarbon group having 1 to 5 carbon atoms, preferably a hydrocarbon group having 1 to 3 carbon atoms. The hydrocarbon group is preferably an alkyl group, more preferably an ethyl group or a methyl group. In formula (1), there are multiple R 2 These can be the same or different from each other. In equation (1), there are multiple R's. 3 These can be the same or different from each other. In equations (1) and (3), there are multiple R's. 4 They may be the same or different from each other.

[0029] In formula (1), a and b each independently represent an integer from 0 to 3, preferably 0 or 1, and more preferably 0. In formulas (1) and (3), c each independently represents an integer from 0 to 4, preferably 0 or 1, and more preferably 0.

[0030] In formulas (1) and (3), the substituted or unsubstituted vinylbenzyl group is preferably the para isomer or the meta isomer, and more preferably the para isomer. If there are two vinylbenzyl groups, they may both be para isomers, both be meta isomers, or a combination of para and meta isomers. The molar ratio of the meta / para isomer is not particularly limited and may be, for example, 0 / 100 to 70 / 30 or 1 / 99 to 55 / 45. Here, with respect to the vinylbenzyl group, the para isomer (para-vinylbenzyl) refers to a structure in which the vinyl group is bonded to the benzyl carbon (benzyl carbon) at the para position. The meta isomer (metavinylbenzyl) refers to a structure in which the vinyl group is bonded to the benzyl carbon at the meta position.

[0031] In one embodiment, polyfluorene preferably has a constituent unit (2) represented by the following general formula (2) together with the above constituent unit (1) as a fluorene unit. [ka]

[0032] In equation (2), R 5 and R 6 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. The alkyl group may be linear or branched, and is preferably linear. The number of carbon atoms in the alkyl group is more preferably 2 to 18, more preferably 3 to 12, and even more preferably 4 to 10.

[0033] In equation (2), R 7 and R 8 Each of these independently represents a hydrocarbon group having 1 to 5 carbon atoms, preferably a hydrocarbon group having 1 to 3 carbon atoms. The hydrocarbon group is preferably an alkyl group, more preferably an ethyl group or a methyl group. In formula (2), there are multiple R 7 These can be the same or different from each other. In equation (2), there are multiple R 8 They may be the same or different from each other.

[0034] In formula (2), d and e each independently represent an integer between 0 and 3, preferably 0 or 1, and more preferably 0.

[0035] The above constituent unit (2) is R in equation (2). 5 and R 6 Preferably, at least one of the constituent units (21) is a constituent unit (21) representing an alkyl group having 1 to 22 carbon atoms. This constituent unit (21) is a fluorene unit in which an alkyl group is introduced as a substituent on the carbon atom at position 9 and which does not have a vinylbenzyl group, and therefore corresponds to the alkylfluorene unit described above.

[0036] The above constituent unit (2) is R in equation (2). 5 and R 6 The constituent units (22) may both represent hydrogen atoms. For example, in one embodiment, the polyfluorene may have constituent units (1), (21), and (22), or it may be composed only of these constituent units (1), (21), and (22).

[0037] In one embodiment, the polyfluorene is preferably represented by the following general formula (4). [ka] R in equation (4) 1 , R 2 , R 3 , R 4 a, b, and c are, respectively, R in equation (1) 1 , R 2 , R 3 , R 4 , is the same as a, b and c, and R in equation (4) 5 , R 6 , R 7 , R 8 d and e are R in equation (2), respectively. 5 , R 6 , R 7 , R 8, d and e are the same. In equation (4), n represents the number of constituent units that make up polyfluorene. Note that in equation (4), R, which is present in multiples in one molecule 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 a, b, c, d, and e may be the same as or different from each other. In formula (4), the left-hand component is component (1) represented by formula (1) (i.e., the vinylbenzylfluorene unit), and the right-hand component is component (2) represented by formula (2). Multiple components (1) present in one molecule may be the same as or different from each other, and multiple components (2) present in one molecule may be the same as or different from each other.

[0038] In one embodiment, the polyfluorene is preferably represented by the following general formula (5). [ka]

[0039] R in equation (5) 1 , R 2 , R 3 , R 4 a, b, and c are, respectively, R in equation (1) 1 , R 2 , R 3 , R 4 , is the same as a, b and c. R in equation (5) 10 , R 11 f and g are, respectively, R in equation (2) 7 , R 8 , is the same as d and e. R in equation (5) 12 , R 13 h and i are, respectively, R in equation (2) 7 , R 8 , is the same as d and e. In equation (5), m represents the number of constituent units that make up polyfluorene. In equation (5), R 5 and R 6 R represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms.5 and R 6 At least one of these represents an alkyl group having 1 to 22 carbon atoms. The alkyl group may be linear or branched, and is preferably linear. The number of carbon atoms in the alkyl group is more preferably 2 to 18, more preferably 3 to 12, and even more preferably 4 to 10. Note that in formula (5), there are multiple R groups in one molecule. 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 10 , R 11 , R 12 , R 13 a, b, c, f, g, h, and i may be the same as or different from each other.

[0040] In equation (5), the left-hand component is component (1) represented by equation (1) (i.e., the vinylbenzylfluorene unit), the middle component is component (21), and the right-hand component is component (22). Multiple components (1) in a single molecule may be identical or different from each other, multiple components (21) in a single molecule may be identical or different from each other, and multiple components (22) in a single molecule may be identical or different from each other.

[0041] The slashes in equations (4) and (5) indicate that the arrangement of each constituent unit is irregular (i.e., random).

[0042] The number-average molecular weight (Mn) of polyfluorene is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, more preferably 2,500 to 15,000, and even more preferably 3,000 to 10,000. The weight-average molecular weight (Mw) of polyfluorene is not particularly limited and may be, for example, 10,000 to 600,000, 20,000 to 550,000, or 40,000 to 500,000. Mn and Mw are polystyrene-converted values ​​measured by gel permeation chromatography (GPC), and detailed measurement methods are described in the Examples section.

[0043] In the polyfluorene according to one embodiment, the introduction rate of a substituted or unsubstituted vinylbenzyl group to the 9-position carbon atom of the fluorene unit is preferably 5 to 60 mol%, more preferably 10 to 55 mol%, and still more preferably 15 to 50 mol%.

[0044] In the polyfluorene according to one embodiment, the introduction rate of an alkyl group to the 9-position carbon atom of the fluorene unit is preferably 10 to 80 mol%, more preferably 30 to 70 mol%, and still more preferably 40 to 65 mol%.

[0045] In the polyfluorene according to one embodiment, the ratio of unsubstituted hydrogen atoms at the 9-position carbon atom of the fluorene unit is not particularly limited, and may be, for example, 0 to 60 mol%, 1 to 40 mol%, or 2 to 30 mol%.

[0046] Here, the introduction rate of the vinylbenzyl group is the ratio (mol%) of the number of hydrogen atoms bonded to the 9-position carbon atom of all fluorene units constituting the polyfluorene that are substituted by the vinylbenzyl group. For example, when the total number of fluorene units is 50, the number of hydrogen atoms bonded to the 9-position carbon atom is 100. If 30 of these hydrogen atoms are substituted by vinylbenzyl groups, the introduction rate of the vinylbenzyl group is 30 mol%. The same applies to the introduction rate of the alkyl group, which is the ratio (mol%) of the number of hydrogen atoms bonded to the 9-position carbon atom of all fluorene units constituting the polyfluorene that are substituted by the alkyl group. The same also applies to the ratio of unsubstituted hydrogen atoms, which is the ratio (mol%) of the number of hydrogen atoms bonded to the 9-position carbon atom of all fluorene units constituting the polyfluorene that remain unsubstituted. These values are 1 calculated from the integration values of 1H-NMR measurement, and the detailed measurement method is as described in the Examples section.

[0047] The method for producing polyfluorene according to the embodiment is not particularly limited. In one embodiment, fluorene may be oxidatively polymerized using an oxidizing agent, and the obtained polymer and vinylbenzyl halide may be reacted in a specific organic solvent in the presence of an alkali to synthesize polyfluorene having a vinylbenzyl group.

[0048] Examples of the oxidizing agent used in the oxidative polymerization include metal catalysts such as iron(III) chloride and hydrogen peroxide. As fluorene as a monomer, for example, fluorene in which the 9-position carbon atom is unsubstituted and represented by the following general formula (6) may be used.

Chemical formula

[0049] In one embodiment, as the above monomer, in addition to the fluorene of formula (6), fluorene in which an alkyl group is introduced into the 9-position carbon atom and represented by formula (7) may be used. By combining fluorene into which an alkyl group is introduced, the solubility of the polymer in the organic solvent can be improved in the step of introducing the vinylbenzyl group after polymerization.

Chemical formula

[0050] As the vinylbenzyl halide, a compound represented by the following general formula (8) may be used.

Chemical formula

[0051] The reaction solvent used when introducing the vinylbenzyl group is not particularly limited, and organic solvents such as toluene and methyl ethyl ketone can be used. Examples of alkalis used in the reaction include alkali metal or alkaline earth metal hydroxides, such as sodium hydroxide and potassium hydroxide. A phase transfer catalyst may be used during the reaction. Onium salts can be used as phase transfer catalysts, such as quaternary ammonium compounds like tetrabutylammonium bromide and quaternary phosphonium compounds like tetrabutylphosphonium bromide. The reaction temperature and reaction time are not particularly limited, and may be, for example, 30 to 100°C for 0.5 to 20 hours.

[0052] After the reaction is complete, an acid is added to neutralize the mixture, and the aqueous layer is separated and removed to remove the salt produced by neutralization. The organic layer remaining after the removal of the aqueous layer is precipitated in an alcohol or alkane as a precipitation solvent to obtain polyfluorene according to one embodiment.

[0053] The polyfluorene according to the embodiment can be cured by heating or other means on its own. Alternatively, it may be made into a curable resin composition by blending it with various components such as curing agents. By curing the polyfluorene or the curable resin composition with heat, light, electron beam, or the like, a cured product according to the embodiment can be obtained. Curing by heat is preferred, and therefore, the curable resin composition is also referred to as a thermosetting resin composition.

[0054] The curable resin composition according to the embodiment contains the above-mentioned polyfluorene, and may also contain various additives such as curing agents, copolymerizable monomers, oligomers and / or polymers, inorganic fillers, photopolymerization initiators, polymerization inhibitors, flame retardants, and colorants.

[0055] Examples of curing agents include benzoyl peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3, t-butylcumyl peroxide, methyl ethyl ketone peroxide, and dicumyl peroxide.

[0056] Examples of monomers, oligomers, and / or polymers copolymerizable with polyfluorene include oligomers or polymers having polymerizable unsaturated groups such as vinyl ester resins, unsaturated polyester resins, and diallyl phthalate resins; various monofunctional or polyfunctional monomers such as aromatic vinyl monomers such as styrene, vinyltoluene, and divinylbenzene; and (meth)acrylic acid-based monomers such as (meth)acrylic acid and its derivatives.

[0057] The applications of the polyfluorene and curable resin composition according to this embodiment are not particularly limited and include various resin materials such as organic EL displays, polymer conductors, printed circuit boards, semiconductor encapsulants, optical components, and electrical and electronic components. [Examples]

[0058] The present invention will be described in more detail below based on examples and comparative examples, but it is not limited thereto.

[0059] (Synthesis Example 1) Synthesis of Compound 1: 9,9-dihexylfluorene 46.2 g of fluorene, 4.4 g of tetrabutylammonium bromide, and 613.8 g of dimethyl sulfoxide were added to a 2 L reactor equipped with a condenser and stirrer, and dissolved at 55°C. Next, 93.3 g of 48% by mass aqueous sodium hydroxide solution and 92.4 g of bromohexane were added, and the reaction was heated to 90°C for 6 hours. After that, 850 g of methylene chloride was added to dilute the mixture. 425 g of water was added, and the mixture was stirred at room temperature for 15 minutes. The aqueous layer was then allowed to stand and separated and removed. This process was repeated twice. The resulting organic layer was desoldered using an evaporator to obtain 88.3 g of compound 1.

[0060] (Synthesis Example 2) Synthesis of Copolymer A 9.6 g of fluorene, 20.0 g of compound 1, 97.6 g of iron(III) chloride, and 400 g of chloroform were placed in a 1 L reaction vessel and reacted at room temperature under nitrogen conditions for 6 hours. 527.2 g of this reaction solution was added to 2000 g of methanol and reprecipitated. The supernatant was then decanted, and the remaining solid was dissolved in 500 g of chloroform. This solution was further reprecipitated in 2000 g of methanol, the supernatant was decanted, and the remaining solid was collected and dried under reduced pressure at 70°C to obtain copolymer A.

[0061] (Synthesis Example 3) Synthesis of Copolymer B 9.6 g of fluorene, 20.0 g of compound 1, 97.6 g of iron(III) chloride, and 400 g of chloroform were placed in a 1 L reaction vessel and reacted at room temperature under nitrogen conditions for 6 hours. 527.2 g of this reaction solution was added to 2000 g of methanol and reprecipitated. The supernatant was then decanted, and the remaining solid was dissolved in 400 g of chloroform. This solution was further reprecipitated in 2000 g of methanol, the supernatant was decanted, and the remaining solid was collected and dried under reduced pressure at 70°C to obtain copolymer B.

[0062] (Example 1) In a 2 L reaction vessel equipped with a condenser and a stirrer, 20.0 g of copolymer A obtained in Synthesis Example 2, 0.61 g of tetrabutylammonium bromide, 12.8 g of vinyl benzyl chloride (meth / para isomer = 5 / 95, trade name: CMS-14, manufactured by AGC Seimi Chemical Co., Ltd.), and 800 g of toluene were added, and the temperature was raised to 65°C. Next, 14.0 g of 48% by mass aqueous sodium hydroxide solution was added, and the reaction was continued at 65°C for 7 hours. Then, 28 g of water and 17.5 g of 35% by mass hydrochloric acid were added, and the mixture was stirred at 45-55°C for 15 minutes, after which it was allowed to stand and the aqueous layer was separated and removed. The resulting organic layer was added dropwise to 1642 g of methanol, and the precipitated solid was collected and vacuum-dried overnight at 40°C to obtain product 1.

[0063] The obtained product 1 had a manganese content of 3200 and a manganese content of 48,900.1 ¹H-NMR confirmed the presence of the fluorene's 9th hydrogen at δ=3.9–4.2 ppm, the benzyl hydrogen of the vinylbenzyl group at δ=3.2–3.7 ppm, the two vinyl hydrogens of the vinylbenzyl group at δ=4.9–5.9 ppm, the α-hydrogen of the alkyl group (hexyl group) at δ=1.9–2.3 ppm, and the β- to ω-hydrogens of the alkyl group (hexyl group) at δ=0.6–1.4 ppm. This identified product 1 as the compound represented by the following formula (5A). The introduction rate of the vinylbenzyl group to the 9th carbon atom of the fluorene unit, calculated from the NMR integral values, was 17.4 mol%, the introduction rate of the hexyl group was 60.5 mol%, and the proportion of unsubstituted hydrogen atoms was 22.1 mol%.

[0064] [ka] (In the formula, R 1 R represents a hydrogen atom, a hexyl group, or a vinylbenzyl group. 6 (where m represents a hydrogen atom or hexyl group, and m represents the number of constituent units that make up polyfluorene.)

[0065] (Example 2) In a 2 L reaction vessel equipped with a condenser and a stirrer, 20.0 g of copolymer B obtained in Synthesis Example 3, 1.7 g of tetrabutylammonium bromide, 11.3 g of vinyl benzyl chloride (meth / para isomer = 5 / 95, trade name: CMS-14, manufactured by AGC Seimi Chemical Co., Ltd.), and 800 g of toluene were added, and the temperature was raised to 65°C. Next, 12.3 g of 48% by mass aqueous sodium hydroxide solution was added, and the reaction was continued at 65°C for 15 hours. Then, 168.8 g of water and 84.4 g of 35% by mass hydrochloric acid were added, and the mixture was stirred at 45-55°C for 15 minutes, after which the aqueous layer was allowed to stand and separated and removed. Furthermore, 160 g of water and 47.7 g of isopropanol were added, and the mixture was stirred at 45-55°C for 15 minutes, after which the aqueous layer was allowed to stand and separated and removed. This procedure was repeated five times. The resulting organic layer was concentrated to a solid content of 7.5% by mass, then added dropwise to 1218 g of heptane. The precipitated solid was collected and vacuum-dried overnight at 40°C to obtain product 2.

[0066] The obtained product 2 had a manganese content of 8500 and a manganese content of 458,500. 1 ¹H-NMR confirmed the presence of the fluorene's 9th hydrogen at δ=3.9–4.2 ppm, the benzyl hydrogen of the vinylbenzyl group at δ=3.2–3.7 ppm, the two vinyl hydrogens of the vinylbenzyl group at δ=4.9–5.9 ppm, the α-hydrogen of the alkyl group (hexyl group) at δ=1.9–2.3 ppm, and the β- to ω-hydrogens of the alkyl group (hexyl group) at δ=0.6–1.4 ppm. This identified product 2 as the compound represented by formula (5A) above. The introduction rate of the vinylbenzyl group to the 9th carbon atom of the fluorene unit, calculated from the NMR integral values, was 46.0 mol%, the introduction rate of the hexyl group was 50.0 mol%, and the proportion of unsubstituted hydrogen atoms was 4.0 mol%.

[0067] (Comparative Example 1) Synthesis of vinyl benzylated polyphenylene ether compounds In a 2L four-necked flask equipped with a temperature controller, stirrer, cooling condenser, and dropping funnel, 158g (0.1 mol) of reactive low molecular weight polyphenylene ether (trade name: Noryl SA-90, manufactured by SABIC Japan LLC), 221g of toluene, and 94.8g of isopropyl alcohol were charged and mixed into a homogeneous solution. Subsequently, 0.96g of tetra-n-butylammonium bromide and 33.6g (0.22 mol) of vinyl benzyl chloride (meth / para isomer = 50 / 50, trade name: CMSP, manufactured by AGC Seimi Chemical Co., Ltd.) were added, and the temperature was raised to 75°C. To this, 53.3g (0.64 mol) of a 48% by mass sodium hydroxide aqueous solution was added dropwise at a rate of 1 / 4 every 2 hours over 30 minutes, and the reaction was carried out at 75°C for a total of 8 hours, resulting in a reaction rate of over 98%. The mixture was then cooled to 50°C, and 295 g of toluene, 31.6 g of isopropanol, and 79 g of water were added. The mixture was neutralized with 66.7 g of 35% by mass aqueous hydrochloric acid solution. The reaction solution was allowed to stand until it separated into two layers, and the lower aqueous layer was removed. The mixture was then washed five times with 15.8 g of isopropanol and 63.2 g of water. The organic layer was dried at 70°C and 50 mmHg until the water content was reduced to less than 0.05% by mass. The solution was then filtered to obtain 345 g of a 50% by mass toluene solution of the vinyl benzylated polyphenylene ether compound (95% by mass yield based on polyphenylene ether). This solution was reprecipitation in a large excess of methanol, and the solid, which was removed by filtration, was dried under reduced pressure at 92°C. The resulting product C1 (vinyl benzylated polyphenylene ether compound) had a Mn of 2200 and a Mw of 4000.

[0068] (Comparative Example 2) In a 2 L reaction vessel equipped with a condenser and stirrer, 149.6 g of fluorene, 105.0 g of para-xylylene dichloride, 8.7 g of tetrabutylammonium bromide, 660 g of toluene, and 300.0 g of 48% by mass aqueous sodium hydroxide solution were added and reacted at 65°C for 4 hours under a nitrogen atmosphere. Next, 91.6 g of vinyl benzyl chloride (meth / para isomer = 50 / 50, trade name: CMS-P, manufactured by AGC Seimi Chemical Co., Ltd.) was added and reacted for a further 9 hours at 65°C. Then, 290.0 g of water and 206.3 g of 35% by mass hydrochloric acid were added and stirred at 45-55°C for 15 minutes, after which the aqueous layer was separated and removed. Further, 132.0 g of water and 33.0 g of isopropanol were added and stirred at 45-55°C, followed by standing and separation and removal of the aqueous layer. This procedure was repeated three times to obtain product C2, represented by the following formula, as a toluene solution. The Mn content of product C2 was 700 and the Mw content was 2400. [ka]

[0069] (Comparative Example 3) A compound containing vinylbenzylfluorene units was prepared as follows, in accordance with the method described in Patent Document 3. In a 200 mL reaction vessel equipped with a condenser, stirrer, and Dean-Stark tube, 16.6 g of fluorene, 3.5 g of 1,4-benzenedimethanol, 21.6 g of benzyl alcohol, and 2.1 g of methanesulfonic acid were added while purging with nitrogen. The temperature was raised to 130°C, and the reaction was carried out for 5 hours while removing the generated water from the system using a Dean-Stark tube. After cooling to 70°C, 1.0 g of sodium hydroxide was added and stirred for 5 minutes, then 100 g of dimethyl sulfoxide and 12 g of sodium hydroxide were added, and the mixture was stirred at 60°C for 30 minutes. Subsequently, while maintaining the internal temperature below 65°C, 29.0 g of vinylbenzyl chloride (meth / para isomer = 5 / 95, trade name: CMS-14, manufactured by AGC Seimi Chemical Co., Ltd.) was added dropwise over 2 hours, and the reaction was carried out at 65°C for 5 hours. Product C3 was obtained by adding 200g of toluene, washing the organic layer five times with 100g of water, and then concentrating the resulting organic layer. The manganese content of product C3 was 450 and the manganese content was 650.

[0070] For products 1-2 and C1-3 obtained in Examples 1-2 and Comparative Examples 1-3, the relative permittivity, dielectric loss tangent, residual carbon percentage, and glass transition temperature of the cured products were evaluated. The measurement and evaluation methods, including the methods for measuring Mn and Mw of the products, as well as the introduction rate of vinylbenzyl groups, the introduction rate of hexyl groups, and the proportion of unsubstituted hydrogen atoms, are as follows.

[0071] <Measurement and Evaluation Methods> [Rate of introduction of vinylbenzyl groups or alkyl groups, and proportion of unsubstituted hydrogen atoms] The product was dissolved in deuterated chloroform and subjected to nuclear magnetic resonance (JEOL) 1 ¹H-NMR measurements (400 MHz) were performed to calculate the integral values ​​of the hydrogen at position 9 of unsubstituted fluorene (δ=3.9~4.2 ppm), the hydrogen at position benzyl of the vinylbenzyl group (δ=3.2~3.7 ppm), and the hydrogen at position α of the alkyl group (hexyl group) (δ=1.9~2.3 ppm). Based on the presence of two substituents or hydrogen atoms bonded to the carbon atom at position 9 of fluorene, the introduction rate of each substituent or the proportion of unsubstituted hydrogen atoms was calculated.

[0072] [Number average molecular weight (Mn), weight average molecular weight (Mw)] The product was dissolved in tetrahydrofuran, and the number-average molecular weight (Mn) and weight-average molecular weight (Mw) in polystyrene equivalent were measured by gel permeation chromatography (GPC) (Prominence, Shimadzu Corporation) using four columns (Shodex GPC columns KF-601, KF-602, KF-603, KF-604, manufactured by Resonaq Corporation) lined up with polystyrene gel as the packing material. The column oven temperature was 40°C, the THF flow rate was 0.6 mL / min, the sample concentration was 0.1% by mass, and the sample injection volume was 10 μL. A differential refractive index detector (Shodex RI-504, manufactured by Resonaq Corporation) was used.

[0073] [Dielectric properties (relative permittivity, dielectric loss tangent)] The product was used as a sample. Using a single-acting compression molding machine (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), 4.0 g of the sample was pressed for 15 minutes at a pressure of 10 MPa and a temperature of 180°C to create a 60 mm × 60 mm × 1 mm thick flat plate. The obtained flat plate was cut to create test pieces with a width of 2 mm, a thickness of 1 mm, and a length of 30 mm, and the relative permittivity (Dk) and dielectric loss tangent (Df) at 10 GHz were measured using a cavity resonator dielectric constant measurement device (manufactured by KEYSIGHT).

[0074] [Remaining coal rate] The oxygen index is used as an indicator of flame retardancy, and the higher the oxygen index, the better the flame retardancy. It is also known that there is a proportional relationship between the oxygen index and the carbon residue rate, and the higher the carbon residue rate, the higher the oxygen index (see DW van Krevelen, "Flame resistance of polymeric materials", POLYMER, 1975, Vol.16, pp. 615-620). Therefore, the carbon residue rate was measured as an indicator of flame retardancy. Specifically, the resin plate prepared in the dielectric property test described above was finely crushed to prepare test specimens. These test specimens were heated to 500°C in an air atmosphere (200 mL / min) and at a heating rate (10°C / min) using a TG-DTA apparatus (manufactured by Rigaku). The carbon residue rate was determined from the ratio (mass %) of the mass of the test specimen after heating to the mass of the test specimen before heating. The higher the carbon residue rate, the better the flame retardancy.

[0075] [Glass transition temperature (Tg)] A test specimen measuring 5 mm in width, approximately 1 mm in thickness, and 30 mm in length was prepared by cutting out a resin plate obtained from the dielectric properties test described above. Next, the glass transition temperature was measured using a dynamic viscoelasticity measuring device: Rheogel-E4000 (manufactured by UBM Co., Ltd.). For this test specimen, the temperature at which the loss tangent (tanδ), measured under conditions of a tensile sine wave, dynamic strain of 5 μm, frequency of 1 Hz, and temperature increase rate of 2 °C / min, took its maximum value was determined as the glass transition temperature.

[0076] [Moldability] Resin plates were fabricated using the pressing conditions described above for the dielectric properties test. Those that yielded a self-standing plate measuring 60mm x 60mm x 1mm thick were classified as "A" (good moldability), while those that did not yield a self-standing plate due to fracture of the cured material, etc., were classified as "B" (poor moldability).

[0077] [Table 1]

[0078] The results are shown in Table 1. A "-" in Table 1 indicates that evaluation was not possible. In Comparative Example 1, product C1 (vinyl benzylated polyphenylene ether compound) showed excellent dielectric properties in its cured product, but a low carbon residue rate resulted in poor flame retardancy. In Comparative Example 2, product C2 showed a higher dielectric loss tangent and inferior dielectric properties compared to Comparative Example 1, and also exhibited a low carbon residue rate and poor flame retardancy. In Comparative Example 3, product C3 could not be obtained as a self-supporting plate under the above pressing conditions, resulting in poor formability. Therefore, the relative permittivity, dielectric loss tangent, and glass transition temperature could not be measured or evaluated. The carbon residue rate was measured using broken fragments after press molding.

[0079] In contrast, Product 1 of Example 1 had a dielectric loss tangent equivalent to that of Comparative Example 1, exhibiting superior dielectric properties, as well as a high carbon residue rate and excellent flame retardancy. Product 2 of Example 2 had a dielectric loss tangent slightly inferior to that of Example 1, but possessed excellent dielectric properties, and also had a higher carbon residue rate than Comparative Example 1, resulting in excellent flame retardancy.

[0080] Furthermore, the various numerical ranges described in this specification can be any combination of their upper and lower limits, and all such combinations are described herein as preferred numerical ranges. Also, the description of a numerical range as "X~Y" means X or greater and Y or less.

[0081] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their omissions, substitutions, and modifications are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

Claims

1. A polyfluorene having vinylbenzylfluorene units as constituent units, wherein 80 mol% or more of the total constituent units are fluorene units, It is expressed by the following general formula (4'), 【Chemistry 1】 In general formula (4'), R1 represents a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or a group represented by general formula (3) below; R2, R3, and R4 each independently represent a hydrocarbon group having 1 to 5 carbon atoms; a and b each independently represent an integer from 0 to 3; c represents an integer from 0 to 4; R5 and R6 each independently represent a hydrogen atom or an alkyl group having 1 to 22 carbon atoms; R7 and R8 each independently represent a hydrocarbon group having 1 to 5 carbon atoms; d and e each independently represent an integer from 0 to 3; n represents the number of constituent units making up polyfluorene; and in general formula (4'), multiple R1, R2, R3, R4, R5, R6, R7, and R8 exist in one molecule. a, b, c, d, and e may be the same or different from each other. 【Chemistry 2】 In general formula (3), R 4 represents a hydrocarbon group having 1 to 5 carbon atoms, c represents an integer from 0 to 4, and * represents the bond position to the fluorene ring. Polyfluorene.

2. The following general formula (2) in the general formula (4'): 【Transformation 3】 The constituent unit (2) represented by R in the general formula (2) is R ５ and R ６ The polyfluorene according to claim 1, wherein at least one of the constituent units (21) represents an alkyl group having 1 to 22 carbon atoms.

3. The polyfluorene according to claim 1, wherein the introduction rate of substituted or unsubstituted vinylbenzyl groups to the carbon atom at position 9 of the fluorene unit is 5 to 60 mol%.

4. The polyfluorene according to claim 1, wherein the introduction rate of alkyl groups to the carbon atom at position 9 of the fluorene unit is 10 to 80 mol%.

5. The polyfluorene according to claim 1, wherein the proportion of unsubstituted hydrogen atoms at the carbon atom at position 9 of the fluorene unit is 1 to 60 mol%.

6. The polyfluorene according to claim 1, wherein the number average molecular weight is 1,000 to 50,000.

7. A curable resin composition comprising polyfluorene according to any one of claims 1 to 6.

8. A cured product obtained by curing polyfluorene according to any one of claims 1 to 6.

9. A cured product obtained by curing the curable resin composition according to claim 7.

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