Thermosetting resin and cured product thereof

Abstract

[Technical Problem to be Solved]: The objective of this invention is to provide a thermosetting resin from which a cured material with excellent dielectric properties can be obtained. [Technical Means for Solving the Problem]: The thermosetting resin of the embodiment of the solution of this invention is a linear vinyl copolymer having repeating units corresponding to monovinyl aromatic compounds and repeating units corresponding to divinyl aromatic compounds, wherein the content of the repeating units corresponding to divinyl aromatic compounds is 5.0 to 25.0 mol%. The ends of the vinyl copolymer have at least one structure derived from a polymerization initiator of general formula (1): R1-N=N-R2, or a polymerization initiator of general formula (2): R3-OO-R4. In general formulas (1) and (2), R1, R2, R3, and R4 independently represent a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group.

Description

Technical Field

[0001] Embodiments of the present invention relate to a thermosetting resin and a cured product thereof, and also to a thermosetting composition containing the thermosetting resin. Prior Art

[0002] In recent years, electronic devices have become smaller and more highly performant, and the performance requirements for various materials used therewith have also increased. For example, a printed circuit board material with a low loss tangent corresponding to high-frequency communication is required.

[0003] Patent Document 1 discloses a vinyl compound which is a thermosetting resin material excellent in heat resistance and electrical properties, and is obtained by converting the ends of a bifunctional PPE (polyphenylene ether) oligomer into vinyl groups.

[0004] Patent Document 2 discloses a curable resin composition which is a curable resin composition for improving dielectric properties, long-term environmental reliability, heat resistance, and adhesion, and contains a polyfunctional vinyl aromatic copolymer containing 2 to 95 mol% of repeating units derived from a divinyl aromatic compound and 5 to 98 mol% of repeating units derived from a monovinyl aromatic compound, a thermoplastic resin, and a thermosetting crosslinking agent.

[0005] [Prior Art Documents]

[0006] [Patent Documents]

[0007]

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-067727.

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2019-178310. Summary of the Invention Problems to be Solved by the Invention

[0010] Although the thermosetting resins described in Patent Document 1 and Patent Document 2 have a low loss tangent, further improvement in dielectric properties is required.

[0011] In view of the above points, an object of embodiments of the present invention is to provide a thermosetting resin capable of obtaining a cured product having excellent dielectric properties. Means for Solving the Problems

[0012] The present invention includes the following embodiments.

[0013] [1] A thermosetting resin, which is a linear vinyl copolymer and has repeating units corresponding to a monovinyl aromatic compound and repeating units corresponding to a divinyl aromatic compound. The content of the repeating units corresponding to the divinyl aromatic compound is 5.0 to 25.0 mol%. The terminal of the linear vinyl copolymer has at least one of the structures derived from a polymerization initiator represented by the general formula (1): R1-N=N-R2 or a polymerization initiator represented by the general formula (2): R3-O-O-R4. In the general formulas (1) and (2), R1, R2, R3, and R4 each independently represent a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group.

[0014] [2] The thermosetting resin according to [1], which has the following structure:

[0015] A structure obtained by copolymerizing a vinylbenzylphosphonium salt and a monovinyl aromatic compound using at least one of the polymerization initiators represented by the aforementioned general formula (1) or the polymerization initiator represented by the aforementioned general formula (2), and reacting the copolymer with formaldehyde.

[0016] [3] The thermosetting resin according to [1] or [2], which is a random copolymer having the repeating units corresponding to the monovinyl aromatic compound and the repeating units corresponding to the divinyl aromatic compound.

[0017] [4] The thermosetting resin according to any one of [1] to [3], wherein the number average molecular weight Mn and the weight average molecular weight Mw are each 3,000 or more and 100,000 or less.

[0018] [5] A cured product formed by curing the thermosetting resin according to any one of [1] to [4].

[0019] [6] A thermosetting composition containing the thermosetting resin according to any one of [1] to [4].

[0020] [7] The thermosetting composition according to [6], which is a printed circuit board material. Advantages of the Invention

[0021] Cured materials with excellent dielectric properties can be obtained from the thermosetting resin according to embodiments of the present invention. Implementation

[0022] The thermosetting resin of this embodiment is a vinyl copolymer having repeating units corresponding to monovinyl aromatic compounds and repeating units corresponding to divinyl aromatic compounds.

[0023] The repeating unit corresponding to the monovinyl aromatic compound is a constituent unit of the vinyl copolymer, and is a constituent unit having a structure formed by addition polymerization of the monovinyl aromatic compound as a monomer. As long as it has the structure corresponding to the monovinyl aromatic compound, it is not limited to being polymerized using the monovinyl aromatic compound, but can also be a structure corresponding to the monovinyl aromatic compound formed by further reaction after polymerization.

[0024] The repeating unit corresponding to a monovinyl aromatic compound can be exemplified by the repeating unit of a monovinyl aromatic compound having the following general formula (3) as shown below, where the vinyl group of the monovinyl aromatic compound is polymerized into a single bond through addition polymerization.

[0025]

[0026] In formula (3), R5 represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. More specifically, R5 can be a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms (more preferably 6 to 20 carbon atoms) selected from the group consisting of phenyl (which may have substituents), biphenyl (which may have substituents), naphthyl (which may have substituents), and triphenyl (which may have substituents). Here, in the case of substituents, the carbon number of R5 is the total carbon number of R5 including the number of carbon atoms contained in the substituent.

[0027] The monovinyl aromatic compound forming the repeating unit can be any aromatic compound having one vinyl group, such as styrene, vinylnaphthalene, vinyl biphenyl, etc.; alkyl styrene (e.g., o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene), dialkyl styrene (e.g., 3,5-dimethylstyrene, 2,5-dimethylstyrene, 2,5-diethylstyrene), alkyl vinyl biphenyl (e.g., ethyl vinyl biphenyl), alkyl vinyl naphthalene (e.g., ethyl vinyl naphthalene), etc., and nucleoalkyl-substituted vinyl aromatic compounds, etc., may be used in any one or in combination of two or more. Styrene is preferred among these.

[0028] The repeating unit corresponding to the divinyl aromatic compound is a constituent unit of the vinyl copolymer, and is a constituent unit with a structure having one vinyl group formed by addition polymerization of the divinyl aromatic compound as a monomer. As long as the repeating unit has a structure corresponding to the divinyl aromatic compound, it is not limited to being polymerized using the divinyl aromatic compound, but can also be formed by further reaction after polymerization to form a structure corresponding to the divinyl aromatic compound.

[0029] The repeating unit corresponding to a divinyl aromatic compound can be exemplified by a repeating unit having a structure in which one vinyl group of a divinyl aromatic compound is formed by addition polymerization to form a single bond, as shown in the following general formula (4).

[0030]

[0031] In formula (4), R6 represents a divalent aromatic hydrocarbon group with 6 to 30 carbon atoms. More specifically, R6 can be a divalent aromatic hydrocarbon group with 6 to 30 carbon atoms (more preferably 6 to 20 carbon atoms) selected from the group consisting of substituents such as phenyl, biphenyldiyl, naphthyl, and triphenyldiyl. Here, in the case of substituents, the carbon number of R6 is the total carbon number of R6 including the number of carbon atoms contained in the substituent.

[0032] The divinyl aromatic compound forming the repeating unit can be any aromatic compound having two vinyl groups, such as divinylbenzene (including isomers or mixtures thereof), divinylnaphthalene (including isomers or mixtures thereof), and divinylbiphenyl (including isomers or mixtures thereof). Any one or a combination of two or more of these compounds can be used. Divinylbenzene (intermediate, para, or mixtures of isomers thereof) is preferred.

[0033] The thermosetting resin of this embodiment is preferably a linear vinyl copolymer. By being linear, the concentration of end groups originating from the polymerization initiator can be reduced, and the dielectric properties can be improved. Here, linear means having a structure in which the repeating units constituting the vinyl copolymer are linked together in a one-dimensional chain and bonded, and without a cross-linked structure.

[0034] In the thermosetting resin of this embodiment, the repeating units corresponding to the monovinyl aromatic compounds and the repeating units corresponding to the divinyl aromatic compounds can be arranged regularly or randomly. Preferably, the thermosetting resin is a random copolymer of repeating units corresponding to the monovinyl aromatic compounds and repeating units corresponding to the divinyl aromatic compounds arranged randomly.

[0035] In the thermosetting resin of this embodiment, in addition to the repeating units corresponding to monovinyl aromatic compounds and repeating units corresponding to divinyl aromatic compounds, repeating units corresponding to other monomers may be contained to a extent that does not impair its effect. Examples of such other monomers include trivinyl aromatic compounds, trivinyl aliphatic compounds, divinyl aliphatic compounds, and monovinyl aliphatic compounds.

[0036] In the thermosetting resin of this embodiment, the content of repeating units corresponding to the divinyl aromatic compound is preferably 5.0 to 25.0 mol%. That is, with 100 mol% of the total repeating units constituting the vinyl copolymer, the content of repeating units corresponding to the divinyl aromatic compound is 5.0 mol% or more and 25.0 mol% or less. By making the content of repeating units corresponding to the divinyl aromatic compound 5.0 mol% or more, the thermosetting properties can be improved and a good cured product can be obtained. Furthermore, by making the content 25.0 mol% or less, the amount of vinyl residue after thermosetting can be reduced. The content of repeating units corresponding to the divinyl aromatic compound is preferably 7.0 mol% or more, and preferably 20.0 mol% or less, and may also be 16.0 mol% or less.

[0037] In the thermosetting resin of this embodiment, the content of repeating units corresponding to the monovinyl aromatic compound is not particularly limited, but is preferably 75.0 to 95.0 mol% with 100 mol% of the total repeating units constituting the vinyl copolymer. The content of repeating units corresponding to the monovinyl aromatic compound is more preferably 80.0 mol% or more, may be 74.0 mol% or more, and is preferably 93.0 mol% or less.

[0038] The thermosetting resin of this embodiment preferably has a structure derived from the polymerization initiator shown in general formula (1) or at least from the polymerization initiator shown in general formula (2). Unlike the commonly used azo initiator azobisisobutyronitrile (AIBN), the polymerization initiator shown in formula (1) is an azo initiator without a cyano group. The polymerization initiator shown in formula (2) is an organic peroxide such as a dialkyl peroxide. The ends of these polymerization initiators do not have polar groups such as active hydrogen groups, thus reducing the loss tangent of the thermosetting resin.

[0039] R1-N=N-R2 (1)

[0040] R3-OO-R4 (2)

[0041] In formulas (1) and (2), R1, R2, R3, and R4 independently represent monovalent saturated hydrocarbon groups or monovalent aromatic hydrocarbon groups, and do not contain heteroatoms. The number of carbon atoms in the saturated hydrocarbon group is not particularly limited, but is preferably 1 to 23, more preferably 4 to 13. The number of carbon atoms in the aromatic hydrocarbon group is not particularly limited, but is preferably 6 to 23, more preferably 6 to 13.

[0042] Saturated hydrocarbon groups can be branched or straight-chain saturated aliphatic hydrocarbon groups (alkyl groups), or saturated alicyclic hydrocarbon groups. Specific examples of saturated hydrocarbon groups include alkyl groups such as tributyl, tripentyl, trihexyl, and 1,1,3,3-tetramethylbutyl, as well as saturated alicyclic hydrocarbon groups such as cyclohexyl.

[0043] Specific examples of aromatic hydrocarbon groups include aryl groups such as phenyl, tolyl, and naphthyl, and aralkyl groups such as isopropylphenyl, benzyl, and phenylethyl.

[0044] In one implementation, R1, R2, R3 and R4 can each be independently a basis as shown in the following general formula (5).

[0045]

[0046] In formula (5), R7, R8, and R9 independently represent a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group. More preferably, R7 represents a monovalent saturated hydrocarbon group with 1 to 20 carbon atoms (more preferably 1 to 10 carbon atoms) or a monovalent aromatic hydrocarbon group with 6 to 20 carbon atoms (more preferably 6 to 10 carbon atoms), and R8 and R9 represent methyl groups. The saturated hydrocarbon groups of R7, R8, and R9 (preferably R7) can be branched or straight-chain, and examples include alkyl groups such as methyl, ethyl, propyl, butyl, heptyl, isopropyl, tributyl, 2,2-dimethylpropyl, and saturated alicyclic hydrocarbon groups such as cyclohexyl. Examples of aromatic hydrocarbons of R7, R8, and R9 (preferably R7) include phenyl, tolyl, and naphthyl.

[0047] When using such polymerization initiators to synthesize vinyl copolymers via free radical polymerization, the ends of the resulting vinyl copolymer typically have a structure derived from the polymerization initiator. When polymerizing with the polymerization initiator of formula (1) above, a vinyl copolymer with R1- and / or R2- at both ends can be obtained. That is, both ends of the vinyl copolymer can be R1-, or both can be R2-, or one end can be R1- and the other end can be R2-.

[0048] In one embodiment, when R1 and R2 are used as polymerization initiators having the groups shown in formula (5) above as polymerization initiators of formula (1), the groups shown in formula (5) above are introduced into both ends of the vinyl copolymer. Therefore, the vinyl copolymer is as shown in formula (6) below.

[0049]

[0050] In formula (6), R5 is as described in formula (3), R6 is as described in formula (4), and R7, R8, and R9 are as described in formula (5). Furthermore, the R7, R8, and R9 at both ends can be the same or different. m and n represent the number of repetitions of the repeating unit corresponding to the monovinyl aromatic compound and the repeating unit corresponding to the divinyl aromatic compound, respectively. These repeating units can be randomly arranged or block-arranged, preferably randomly arranged.

[0051] On the other hand, when using the polymerization initiator of the above formula (2) for polymerization, a vinyl copolymer with R3O- and / or R4O- at both ends can be obtained. That is, both ends of the vinyl copolymer can be R3O-, or both can be R4O-, or one end can be R3O- and the other end can be R4O-.

[0052] In one embodiment, when R3 and R4 are polymer initiators having the base shown in formula (5) above as polymer initiators of formula (2), the vinyl copolymer shown in formula (7) below can be obtained.

[0053]

[0054] In formula (7), R5 is as described in formula (3), R6 is as described in formula (4), and R7, R8, and R9 are as described in formula (5). Furthermore, the R7, R8, and R9 at both ends can be the same or different. m and n represent the number of repetitions of the repeating unit corresponding to the monovinyl aromatic compound and the repeating unit corresponding to the divinyl aromatic compound, respectively. These repeating units can be randomly arranged or block-arranged, preferably randomly arranged.

[0055] The number-average molecular weight (Mn) of the thermosetting resin of this embodiment is preferably 3,000 to 100,000. By making the number-average molecular weight (Mn) 3,000 or higher, the concentration of end groups originating from the polymerization initiator can be reduced, and the dielectric properties can be improved. Furthermore, by making the number-average molecular weight (Mn) 100,000 or lower, the high viscosity of the thermosetting resin solution can be suppressed, and processability can be improved. Also, the larger the molecular weight, the greater the tendency for the amount of vinyl groups remaining after thermosetting. From the viewpoint of dielectric properties, the number-average molecular weight (Mn) is preferably 7,000 or higher, more preferably 10,000 or higher, even more preferably 15,000 or higher, and may also be 20,000 or higher. From the viewpoint of processability and vinyl group retention, the number-average molecular weight (Mn) is preferably 50,000 or lower, more preferably 40,000 or lower, and may also be 30,000 or lower.

[0056] The weight-average molecular weight (Mw) of the thermosetting resin of this embodiment is preferably 3,000 to 100,000. By having a weight-average molecular weight (Mw) of 3,000 or more, the concentration of end groups originating from the polymerization initiator can be reduced, and the dielectric properties can be improved. Furthermore, by having a weight-average molecular weight (Mw) of 100,000 or less, the high viscosity of the thermosetting resin when forming a solution can be suppressed, processability can be improved, and the amount of vinyl residue can be reduced. From the viewpoint of dielectric properties, a weight-average molecular weight (Mw) of 10,000 or more, more preferably 20,000 or more, and can be 30,000 or more, or can be 40,000 or more. From the viewpoint of processability and vinyl residue, a weight-average molecular weight (Mw) of 90,000 or less, more preferably 80,000 or less, and can also be 70,000 or less.

[0057] In the thermosetting resin of this embodiment, the molecular weight distribution Mw / Mn, which is the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is not particularly limited, but is preferably 4.0 or less, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0.

[0058] Here, the number-average molecular weight Mn and weight-average molecular weight Mw are converted from the polystyrene obtained by gel permeation chromatography (GPC).

[0059] The method for manufacturing the thermosetting resin of this embodiment is not particularly limited. As a method for synthesizing linear vinyl copolymers, in a preferred embodiment, at least one of the polymerization initiators shown in formula (1) or formula (2) is used to copolymerize vinyl benzyl phosphonium salt with a monovinyl aromatic compound, and the resulting copolymer is reacted with formaldehyde. However, this manufacturing method is not limited.

[0060] Vinylbenzylphosphonium salts are preferably vinylbenzylphosphonium halides. Examples of phosphonic groups in vinylbenzylphosphonium salts include quaternary phosphonic groups such as trialkylphosphonium, triarylphosphonium, and triarylalkylphosphonium. Furthermore, examples of halogens that form salts with the phosphonic group include chlorine and bromine.

[0061] The copolymerization of vinyl benzyl phosphonium salt with monovinyl aromatic compounds can be carried out using known vinyl polymerization methods. The polymerization initiator is a free radical polymerization initiator as shown in formula (1) and / or formula (2) above, thereby obtaining a copolymer having repeating units derived from vinyl benzyl phosphonium salt and repeating units derived from monovinyl aromatic compounds.

[0062] Next, the copolymer can be reacted with formaldehyde using the known Viti reaction, in which the copolymer is treated with alkali and then reacted with formaldehyde to remove phosphonium groups and introduce vinyl groups.

[0063] If this manufacturing method is used, the vinyl benzyl phosphonium salt in the copolymerization step is a monovinyl group, so a straight-chain copolymer without branches can be obtained. After copolymerization, vinyl groups are introduced into the repeating units derived from the vinyl benzyl phosphonium salt, so a straight-chain vinyl copolymer with repeating units corresponding to the divinyl aromatic compounds and without branches can be obtained.

[0064] The thermosetting composition of this embodiment contains the aforementioned thermosetting resin. As long as the composition has the property of being curable by heat, the content of the thermosetting resin in the thermosetting composition is not particularly limited. For example, relative to 100% by mass of the solids content of the thermosetting composition (the amount after removing the organic solvent if it contains the organic solvent, and the total amount of the composition if it does not contain the organic solvent), it can be 1 to 99% by mass, or 10 to 95% by mass.

[0065] In addition to the thermosetting resins mentioned above, thermosetting compositions may contain other thermosetting resins (thermosetting crosslinking agents), thermoplastic resins, fillers, flame retardants, curing accelerators, polymerization initiators, defoamers, heat stabilizers, antistatic agents, ultraviolet absorbers, colorants such as dyes or pigments, lubricants, dispersants, and other various components.

[0066] Furthermore, the thermosetting composition may contain an organic solvent to adjust its viscosity, and the thermosetting composition may be a solution containing the aforementioned thermosetting resin. The organic solvent may be any solvent capable of dissolving the aforementioned thermosetting resin, such as ketones like acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters like ethyl acetate, propyl acetate, and butyl acetate; amines like dimethyl acetamide and dimethylformamide; and aromatic hydrocarbons like toluene and xylene. Any one or a combination of two or more of these solvents may be used.

[0067] The thermosetting resin or thermosetting composition of this embodiment contains vinyl groups in the molecular chain of the vinyl copolymer, thus allowing for cross-linking through polymerization and obtaining a cured product through thermosetting. This cured product exhibits low loss tangent and excellent dielectric properties, making it suitable for electronic applications such as printed circuit board materials and semiconductor sealing materials. In other words, one embodiment of the thermosetting composition is a thermosetting composition for electronic materials.

[0068] Printed substrate materials can include rigid printed substrate materials such as single-sided substrates, double-sided substrates, multilayer substrates, and additive manufacturing substrates, as well as flexible printed substrate materials in the form of films or sheets. Furthermore, due to its low loss tangent, it is suitable for use as a high-frequency substrate material in high-frequency communication equipment.

[0069] (Example)

[0070] The following examples further illustrate the invention, but the invention is not limited to these examples.

[0071] <Measurement and Evaluation Methods>

[0072] [Mohr ratio of styrene to divinylbenzene, divinylbenzene ratio]

[0073] The products obtained in Examples 1 to 13 and Comparative Examples 1 to 8 were dissolved in deuterated chloroform and measured by 1H-NMR using a nuclear magnetic resonance apparatus (JEOL manufactured). The molar ratios corresponding to repeating units of styrene and repeating units corresponding to divinylbenzene were determined. The content of repeating units corresponding to styrene (styrene ratio) and the content of repeating units corresponding to divinylbenzene (divinylbenzene ratio) relative to 100 molars of all repeating units were calculated.

[0074] [Number average molecular weight, weight average molecular weight]

[0075] The products obtained in Examples 1 to 13 and Comparative Examples 1 to 8 were dissolved in tetrahydrofuran, and the converted number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polystyrene were determined by gel permeation chromatography (GPC) (Prominence, Shimadzu Corporation) using four columns (Shodex GPC columns KF-601, KF-602, KF-603, and KF-604, manufactured by Showa Denko) with polystyrene-based 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, the sample injection volume was 10 μL, and a differential refractive index detector (Shodex RI-504, manufactured by Showa Denko) was used.

[0076] [Dielectric constant, loss tangent]

[0077] The products obtained in Examples 1 to 13 and Comparative Examples 1 to 8 were used as test samples. A single-action compression molding machine (manufactured by Yasuda Seiki Co., Ltd.) was used to pressurize 1.5 g of the test sample for 15 minutes at a pressure of 10 Pa and a temperature of 220 °C to produce a 30 mm × 30 mm × 1 mm thick plate. The plate was cut to produce test pieces with a width of 2 mm, a thickness of 1 mm, and a length of 30 mm. The dielectric constant and loss tangent at 10 GHz were measured using a cavity resonator dielectric constant measuring device (manufactured by KEYSIGHT).

[0078] [Thermosetting properties]

[0079] The products obtained in Examples 1 to 13 and Comparative Examples 1 to 8 were used as samples, and the temperature was increased from room temperature to 350°C at a heating rate of 10°C / min using a differential scanning calorimeter (made by Rigaku). Those with a heat of 20 J / g or more at the heating peak were marked "○" (good thermosetting properties), and those with less than 20 J / g were marked "×" (poor thermosetting properties).

[0080] [Vinyl Residue]

[0081] The products obtained in Examples 1 to 13 and Comparative Examples 1 to 8, along with plates prepared using [dielectric constant, loss tangent], were used as samples. The vinyl peak area (1620 to 1640 cm⁻¹) and aromatic peak area (1420 to 1470 cm⁻¹) of each product and plate were measured using a Fourier transform infrared spectrophotometer: Nicolet 6700 (Thermo Fisher Scientific). The vinyl reactivity of the product under pressure was determined from the measured peak areas using the following <Formula A>.

[0082] <Formula A>: Vinyl reaction rate (%) = {1 - (Vinyl peak area of ​​plate × Aromatic peak area of ​​product) / (Aromatic peak area of ​​plate × Vinyl peak area of ​​product)} × 100.

[0083] The amount of vinyl residue is calculated from the divinylbenzene ratio and the vinyl reaction rate using the following formula (B).

[0084] <Formula B>: Vinyl residue (mol%) = divinylbenzene ratio (mol%) × (100 - vinyl reactivity (%)) / 100.

[0085] Generally speaking, if there is a high amount of residual vinyl, the durability of the product will be reduced due to the oxidation of vinyl. Therefore, a vinyl residue of 9 moles or more is marked "×" (high amount of residual vinyl), and a vinyl residue of less than 9 moles is marked "○" (low amount of residual vinyl).

[0086] (Synthetic Example 1) Synthesis of Compound 1: Triphenylvinylbenzylphosphonium chloride

[0087] 1.5 moles (228.9 g) of vinylbenzyl chloride (trade name: CMS-14, manufactured by AGC SEIMI CHEMICAL), 1.8 moles (472.1 g) of triphenylphosphine, and 622.4 g of dimethylformamide were added to a 2.0 L reactor and reacted at 70 °C for 3 hours under nitrogen conditions, thereby precipitating a white solid. After thoroughly washing the solid with acetone, the solid was dried under reduced pressure at 92 °C to recover 490 g of compound 1.

[0088] (Synthesis Example 2) Synthesis of Copolymer A

[0089] 45g of styrene, 13.8g of compound 1,2,2'-azobis(2,4,4-trimethylpentane) (trade names: VR-110, FUJIFILM, and Kohden Pharmaceutical), 0.44g of dimethylformamide, and 137.3g of styrene were added to a 500mL reactor and reacted at 120°C for 3.5 hours under nitrogen conditions to obtain copolymer A in the form of a dimethylformamide solution.

[0090] (Synthesis Example 3) Synthesis of Copolymer B

[0091] 22.5 g of styrene, 14.9 g of compound 1, 2,2'-azobis(2,4,4-trimethylpentane), 0.26 g of dimethylformamide, and 87.4 g of dimethylformamide were added to a 300 mL reactor and reacted at 120 °C for 3 hours under nitrogen conditions to obtain copolymer B in the form of dimethylformamide solution.

[0092] (Synthesis Example 4) Synthesis of Copolymer C

[0093] 22.5 g and 22.4 g of styrene, 0.34 g of compound 1, 2,2'-azobis(2,4,4-trimethylpentane), and 104.8 g of dimethylformamide were added to a 500 mL reactor and reacted at 120 °C for 3 hours under nitrogen conditions to obtain copolymer C in the form of a dimethylformamide solution.

[0094] (Synthesis Example 5) Synthesis of Copolymer D

[0095] 22.5 g of styrene, 6.9 g of compound 1, 2,2'-azobis(2,4,4-trimethylpentane), 2.1 g of dimethylformamide, and 68.6 g of dimethylformamide were added to a 500 mL reactor and reacted at 120 °C for 2 hours under nitrogen conditions to obtain copolymer D in the form of dimethylformamide solution.

[0096] (Synthesis Example 6) Synthesis of Copolymer E

[0097] 22.5 g of styrene, 15.0 g of compound 1, 2,2'-azobis(2,4,4-trimethylpentane), 2.8 g of dimethylformamide, and 87.4 g of dimethylformamide were added to a 500 mL reactor and reacted at 120 °C for 1.5 hours under nitrogen conditions to obtain copolymer E in the form of dimethylformamide solution.

[0098] (Synthesis Example 7) Synthesis of Copolymer F

[0099] 525.0 g of styrene, 160.9 g of compound 1, 1.8 g of di-tert-butyl peroxide (trade name: PERBUTYL D, Nippon Oil Manufacturing Co., Ltd.), and 1600.4 g of dimethylformamide were added to a 3.0 L reactor and reacted at 132 °C for 7 hours under nitrogen conditions to obtain copolymer F in the form of dimethylformamide solution.

[0100] (Synthesis Example 8) Synthesis of Copolymer G

[0101] 22.5 g of styrene, 15.0 g of compound 1, 0.12 g of di-tert-butylperoxide, and 87.5 g of dimethylformamide were added to a 500 mL reactor and reacted at 132 °C for 6 hours under nitrogen conditions to obtain copolymer G in the form of a dimethylformamide solution.

[0102] (Synthesis Example 9) Synthesis of Copolymer H

[0103] 343.6 g and 342.3 g of styrene, compound 1, 1.8 g of di-tert-butyl peroxide, and 1600.4 g of dimethylformamide were added to a 3.0 L reactor and reacted at 132 °C for 6 hours under nitrogen conditions to obtain copolymer H in the form of dimethylformamide solution.

[0104] (Synthesis Example 10) Synthesis of Copolymer I

[0105] 525.0 g of styrene, 160.9 g of compound 1, 15.1 g of di-tert-butylperoxide, and 1600.4 g of dimethylformamide were added to a 3.0 L reactor and reacted at 132 °C for 3 hours under nitrogen conditions to obtain copolymer I in the form of a dimethylformamide solution.

[0106] (Synthetic Example 11) Synthesis of Copolymer J

[0107] 22.5 g of styrene, 15.0 g of compound 1, 0.46 g of di-tert-butylperoxide, and 87.4 g of dimethylformamide were added to a 500 mL reactor and reacted at 132 °C for 6 hours under nitrogen conditions to obtain copolymer J in the form of a dimethylformamide solution.

[0108] (Synthesis Example 12) Synthesis of copolymer K

[0109] 45g of styrene, 13.8g of compound 1, 0.20g of di-tert-hexyl peroxide (trade name: PERHEXYL D, Nippon Oil Manufacturing Co., Ltd.), and 137.2g of dimethylformamide were added to a 500mL reactor and reacted at 122°C for 7 hours under nitrogen conditions to obtain copolymer K in the form of dimethylformamide solution.

[0110] (Synthetic Example 13) Synthesis of copolymer L

[0111] 45 g of styrene, 13.8 g of compound 1, 0.17 g of dipentyl peroxide (trade name: LUPEROX DTA, manufactured by ARKEMA Yoshitomi), and 137.2 g of dimethylformamide were added to a 500 mL reactor and reacted at 125 °C for 6 hours under nitrogen conditions to obtain copolymer L in the form of a dimethylformamide solution.

[0112] (Synthetic Example 14) Synthesis of copolymer M

[0113] 20 g of styrene, 6.1 g of compound 1, 0.12 g of diisopropylbenzene peroxide (prepared by Nacalai Tesque), and 61.0 g of dimethylformamide were added to a 300 mL reactor and reacted at 125 °C for 3.5 hours under nitrogen conditions to obtain copolymer M in the form of a dimethylformamide solution.

[0114] (Comparative Synthesis Example 1) Synthesis of Copolymer N

[0115] 17.4 g of styrene, 2.7 g of compound 1, 0.16 g of 2,2'-azobis(2,4,4-trimethylpentane), and 46.1 g of dimethylformamide were added to a 300 mL reactor and reacted at 120 °C for 3 hours under nitrogen conditions to obtain copolymer N in the form of a dimethylformamide solution.

[0116] (Comparative Synthesis Example 2) Synthesis of Copolymer O

[0117] 20g of styrene, 26.6g of compound 1, 0.35g of 2,2'-azobis(2,4,4-trimethylpentane), and 108.7g of dimethylformamide were added to a 500mL reactor and reacted at 120°C for 2 hours under nitrogen conditions to obtain copolymer O in the form of a dimethylformamide solution.

[0118] (Comparative Synthesis Example 3) Synthesis of Copolymer P

[0119] 17.0 g of styrene, 2.7 g of compound 1, 0.08 g of di-tert-butylperoxide, and 46.0 g of dimethylformamide were added to a 500 mL reactor and reacted at 132 °C for 6 hours under nitrogen conditions to obtain copolymer P in the form of dimethylformamide solution.

[0120] (Comparative Synthesis Example 4) Synthesis of copolymer Q

[0121] 552.12 g of styrene, 169.2 g of compound 1, 3.27 g of azobisisobutyronitrile (AIBN), and 1682.68 g of dimethylformamide were added to a 3.0 L reactor and reacted at 70 °C for 9 hours under nitrogen conditions. The reaction solution was concentrated under reduced pressure and dissolved in dichloromethane, followed by reprecipitation in a very excess of isopropanol. The supernatant was then decanted, and the remaining solid was dried under reduced pressure at 92 °C to recover 285.0 g of copolymer Q.

[0122] (Comparative Synthesis Example 5) Synthesis of Copolymer R

[0123] 110g of styrene, 62.6g of compound 1, 0.78g of azobisisobutyronitrile, and 258.9g of dimethylformamide were added to a 1.0L reactor and reacted at 70°C for 9 hours under nitrogen conditions to obtain copolymer R in the form of a dimethylformamide solution.

[0124] (Comparative Synthesis Example 6) Synthesis of Copolymer S

[0125] 142.7 g of styrene, 21.2 g of compound 1, 0.75 g of azobisisobutyronitrile (AIBN), and 245.9 g of dimethylformamide were added to a 1.0 L reactor and reacted at 70 °C for 9 hours under nitrogen conditions. The reaction solution was concentrated under reduced pressure and dissolved in dichloromethane, followed by reprecipitation in a very excess of isopropanol. The supernatant was then decanted, and the residual solid was dried under reduced pressure at 92 °C to recover 102.4 g of copolymer S.

[0126] (Comparative Synthesis Example 7) Synthesis of Copolymer T

[0127] 55.2 g of styrene, 16.9 g of compound 1, 3.24 g of azobisisobutyronitrile, and 108.17 g of dimethylformamide were added to a 500 mL reactor and reacted at 70 °C for 5 hours under nitrogen conditions to obtain copolymer T in the form of a dimethylformamide solution.

[0128] (Comparative Synthesis Example 8) Synthesis of Copolymer U

[0129] 50.2 g of styrene, 50.0 g of compound 1, 0.45 g of azobisisobutyronitrile, and 186.09 g of dimethylformamide were added to a 500 mL reactor and reacted under nitrogen conditions at 68 °C for 8 hours and 30 minutes to obtain copolymer U in the form of dimethylformamide solution.

[0130] (Example 1)

[0131] 50.0 g of dimethylformamide solution, 8.3 g of 37% formalin, 10.2 g of 28% potassium hydroxide aqueous solution, and 71.8 g of tetrahydrofuran of copolymer A obtained in Synthesis Example 2 were added to a 500 mL reactor and reacted at room temperature for 3 hours. The reaction solution was then precipitated again in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 1. Product 1 had a Mn of 25600, a Mw of 71300, a styrene ratio of 92.9 mol%, and a divinylbenzene ratio of 7.1 mol.

[0132] (Example 2)

[0133] 120.0 g of dimethylformamide solution, 32.0 g of 37% formalin, 39.5 g of 28% potassium hydroxide aqueous solution, and 197.3 g of tetrahydrofuran of copolymer B obtained in Synthesis Example 3 were added to a 1.0 L reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 2. Product 2 had a Mn of 21800, a Mw of 47700, a styrene ratio of 84.8 mol%, and a divinylbenzene ratio of 15.2 mol.

[0134] (Example 3)

[0135] 150.0 g of dimethylformamide solution, 50.5 g of 37% formalin, 62.3 g of 28% potassium hydroxide aqueous solution, and 254.4 g of tetrahydrofuran of copolymer C obtained in Synthesis Example 4 were added to a 1.0 L reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in methanol / water = 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 3. Product 3 had a Mn of 21600, a Mw of 55500, a styrene ratio of 77.8 mol%, and a divinylbenzene ratio of 22.2 mol.

[0136] (Example 4)

[0137] 98.0 g of dimethylformamide solution, 15.6 g of 37% formalin, 19.2 g of 28% potassium hydroxide aqueous solution, and 159.8 g of tetrahydrofuran of copolymer D obtained in Synthesis Example 5 were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 4. Product 4 had a Mn of 7800, a Mw of 24200, a styrene ratio of 92.1 mol%, and a divinylbenzene ratio of 7.9 mol.

[0138] (Example 5)

[0139] 121.0 g of dimethylformamide solution, 33.5 g of 37% formalin, 41.3 g of 28% potassium hydroxide aqueous solution, and 204.0 g of tetrahydrofuran of copolymer E obtained in Synthesis Example 6 were added to a 1.0 L reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in methanol / water = 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 5. Product 5 had a Mn of 7100, a Mw of 19900, a styrene ratio of 83.9 mol%, and a divinylbenzene ratio of 16.1 mol.

[0140] (Example 6)

[0141] 1076.4 g of dimethylformamide solution, 191.5 g of 37% formalin, 236.4 g of 28% potassium hydroxide aqueous solution, and 1214.8 g of tetrahydrofuran of copolymer F obtained in Synthetic Example 7 were added to a 3.0 L reactor and reacted at room temperature for 4 hours. Dichloromethane was added to the reaction solution, followed by precipitation in methanol. The solid was filtered off and dissolved in dichloromethane. The organic layer was washed with distilled water and then precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 6. Product 6 had a Mn of 40000, a Mw of 88000, a styrene ratio of 91.1 mol%, and a divinylbenzene ratio of 8.9 mol.

[0142] (Example 7)

[0143] 118.1 g of dimethylformamide solution, 26.6 g of 37% formalin, 32.7 g of 28% potassium hydroxide aqueous solution, and 123.2 g of tetrahydrofuran of copolymer G obtained in Synthesis Example 8 were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was then precipitated again in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 7. Product 7 had a Mn of 35000, a Mw of 65400, a styrene ratio of 81.1 mol%, and a divinylbenzene ratio of 18.9 mol.

[0144] (Example 8)

[0145] 1400.0 g of dimethylformamide solution, 329.0 g of 37% formalin, 406.1 g of 28% potassium hydroxide aqueous solution, and 1000.0 g of tetrahydrofuran of copolymer H obtained in Synthesis Example 9 were added to a 5.0 L reactor and reacted at room temperature for 4 hours. Dichloromethane was added to the reaction solution, followed by precipitation in methanol. The solid was filtered off and dissolved in dichloromethane. The organic layer was washed with distilled water and then precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 8. Product 8 had a Mn of 39000, a Mw of 91000, a styrene ratio of 79.2 mol%, and a divinylbenzene ratio of 20.8 mol.

[0146] (Example 9)

[0147] 1080.0 g of dimethylformamide solution, 191.4 g of 37% formalin, 256.4 g of 28% potassium hydroxide aqueous solution, and 1213.0 g of tetrahydrofuran of copolymer I obtained in Synthesis Example 10 were added to a 3.0 L reactor and reacted at room temperature for 4 hours. Dichloromethane was added to the reaction solution, followed by precipitation in methanol. The solid was filtered off and dissolved in dichloromethane. The organic layer was washed with distilled water and then precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 9. Product 9 had a Mn of 17000, a Mw of 47000, a styrene ratio of 92.5 mol%, and a divinylbenzene ratio of 7.5 mol.

[0148] (Example 10)

[0149] 124.9 g of dimethylformamide solution, 28.2 g of 37% formalin, 34.4 g of 28% potassium hydroxide aqueous solution, and 139.4 g of tetrahydrofuran of copolymer J obtained in Synthesis Example 11 were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 10. Product 10 had a Mn of 18300, a Mw of 45100, a styrene ratio of 81.8 mol%, and a divinylbenzene ratio of 18.2 mol.

[0150] (Example 11)

[0151] 58.0 g of a dimethylformamide solution of copolymer K obtained in Synthesis Example 12, 4.8 g of 37% formalin, and 6.0 g of 28% potassium hydroxide aqueous solution were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was then precipitated again in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 11. Product 11 had a Mn of 36,000, a Mw of 64,000, a styrene ratio of 92.2 mol%, and a divinylbenzene ratio of 7.8 mol.

[0152] (Example 12)

[0153] 130.0 g of dimethylformamide solution, 20.7 g of 37% formalin, 25.5 g of 28% potassium hydroxide aqueous solution, and 223.9 g of tetrahydrofuran of copolymer L obtained in Synthesis Example 13 were added to a 1.0 L reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 12. Product 12 had a Mn of 24800, a Mw of 69000, a styrene ratio of 92.4 mol%, and a divinylbenzene ratio of 7.6 mol.

[0154] (Example 13)

[0155] 87.1 g of dimethylformamide solution, 13.5 g of 37% formalin, 16.7 g of 28% potassium hydroxide aqueous solution, and 130.8 g of tetrahydrofuran of copolymer M obtained in Synthesis Example 14 were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 13. Product 13 had a Mn of 16800, a Mw of 41800, a styrene ratio of 91.2 mol%, and a divinylbenzene ratio of 8.8 mol.

[0156] (Comparative Example 1)

[0157] 66.2 g of a dimethylformamide solution of copolymer N obtained in Comparative Synthesis Example 1, 5.5 g of 37% formalin, 7.7 g of 28% potassium hydroxide aqueous solution, and 103.2 g of tetrahydrofuran were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was then reprecipitated in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in a methanol / water ratio of 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 14. Product 14 had a Mn of 22000, a Mw of 47500, a styrene ratio of 95.5 mol%, and a divinylbenzene ratio of 4.5 mol.

[0158] (Comparative Example 2)

[0159] 151.0 g of a dimethylformamide solution, 59.8 g of 37% formalin, 73.7 g of 28% potassium hydroxide aqueous solution, and 269.4 g of tetrahydrofuran of copolymer O obtained in Comparative Synthesis Example 2 were added to a 1.0 L reactor and reacted at room temperature for 5 hours. The reaction solution was reprecipitated in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in methanol / water = 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 15. Product 15 had a Mn of 12600, a Mw of 52200, a styrene ratio of 71.4 mol%, and a divinylbenzene ratio of 28.6 mol.

[0160] (Comparative Example 3)

[0161] 65.7 g of dimethylformamide solution, 5.4 g of 37% formalin, 7.1 g of 28% potassium hydroxide aqueous solution, and 72.6 g of tetrahydrofuran of copolymer P obtained in Comparative Synthesis Example 3 were added to a 500 mL reactor and reacted at room temperature for 5 hours. The reaction solution was reprecipitated in methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in methanol / water = 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 16. Product 16 had a Mn of 19700, a Mw of 52000, a styrene ratio of 95.4 mol%, and a divinylbenzene ratio of 4.6 mol.

[0162] (Comparative Example 4)

[0163] 285.0 g of copolymer Q obtained from Comparative Synthesis Example 4, 169.83 g of 37% formalin, 209.66 g of 28% potassium hydroxide aqueous solution, and 665.0 g of tetrahydrofuran were added to a 3 L reactor and reacted at room temperature for 4 hours. The reaction solution was then reprecipitated in a very excess of methanol, filtered, and the solid was dissolved in dichloromethane. The organic layer was washed with distilled water, and the solution was reprecipitated in a very excess of methanol / water (7 / 3). The solid was then filtered and dried under reduced pressure at 92 °C to recover product 17. Product 17 had a Mn of 24700, a Mw of 39800, a styrene ratio of 92.1 mol%, and a divinylbenzene ratio of 7.9 mol.

[0164] (Comparative Example 5)

[0165] 20 g of dimethylformamide solution, 3.8 g of 37% formalin, 9.4 g of 28% potassium hydroxide aqueous solution, and 24 g of dimethylformamide were added to a 500 mL reactor and reacted at room temperature for 1 hour. The precipitated solid was dissolved in dichloromethane, reprecipitated in isopropanol, and filtered to collect the solid. It was then dissolved again in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered and dried under reduced pressure at 92 °C to recover product 18. Product 18 had a Mn of 26600, a Mw of 48900, a styrene ratio of 85.3 mol%, and a divinylbenzene ratio of 14.7 mol.

[0166] (Comparative Example 6)

[0167] 6.00 g of copolymer S obtained from Comparative Synthesis Example 6, 5.47 g of 37% formalin, 6.00 g of 28% potassium hydroxide aqueous solution, and 150 g of tetrahydrofuran were added to a 500 mL reactor and reacted at room temperature for 4 hours. The reaction solution was then precipitated in methanol, filtered, and the solid was dried under reduced pressure at 92 °C to recover product 19. Product 19 had a Mn of 24300, a Mw of 39200, a styrene ratio of 95.7 mol%, and a divinylbenzene ratio of 4.3 mol.

[0168] (Comparative Example 7)

[0169] 29.7 g of dimethylformamide solution, 6.1 g of 37% formalin, 7.6 g of 28% potassium hydroxide aqueous solution, and 70 g of tetrahydrofuran of copolymer T obtained in Comparative Synthesis Example 7 were added to a 300 mL reactor and reacted at room temperature for 2 hours and 30 minutes. The reaction solution was reprecipitated in methanol, the solid was filtered off, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol / water = 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 20. Product 20 had a Mn of 3400, a Mw of 8400, a styrene ratio of 91.9 mol%, and a divinylbenzene ratio of 8.1 mol.

[0170] (Comparative Example 8)

[0171] 280.0 g of dimethylformamide solution, 48.5 g of 37% formalin, 59.5 g of 28% potassium hydroxide aqueous solution, and 93.8 g of tetrahydrofuran of copolymer U obtained in Comparative Synthesis Example 8 were added to a 1 L reactor and reacted at room temperature for 7 hours. Dichloromethane was added to the reaction solution, followed by precipitation in methanol. The solid was filtered off and dissolved in dichloromethane. The organic layer was washed with distilled water and then precipitated again in a methanol / water ratio of 7 / 3. The solid was then filtered off and dried under reduced pressure at 92 °C to recover product 21. Product 21 had a Mn of 24200, a Mw of 43300, a styrene ratio of 75.0 mol%, and a divinylbenzene ratio of 25.0 mol.

[0172] The dielectric constant, loss tangent, thermosetting properties, and vinyl residue of the products obtained in Examples 1 to 13 and Comparative Examples 1 to 8 were evaluated. The results are presented in Tables 1 to 5 below.

[0173] [Table 1]

[0174] [Table 2]

[0175] [Table 3]

[0176] [Table 4]

[0177] [Table 5]

[0178] As shown in Tables 4 and 5, the divinylbenzene ratios in Comparative Examples 1, 3, and 6 were low, resulting in insufficient thermosetting properties and making it impossible to prepare test pieces for evaluating dielectric constant and loss tangent. Therefore, it was impossible to determine the dielectric constant and loss tangent, and also impossible to evaluate the amount of vinyl residue.

[0179] In Comparative Example 2, the divinylbenzene ratio was high, resulting in a lower amount of unreacted vinyl groups remaining.

[0180] In Comparative Examples 4, 5 and 7, and 8, azobisisobutyronitrile was used as a polymerization initiator when synthesizing the copolymer, so cyano groups were present in the product, resulting in poor loss tangent.

[0181] In this regard, the products of Examples 1 to 13 have a divinylbenzene ratio within the specified range, thus exhibiting excellent thermosetting properties and a lower vinyl residue compared to Comparative Example 2. Furthermore, the products of Examples 1 to 13 are linear vinyl copolymers with terminal structures derived from the polymerization initiators of Formula (1) or (2) described above, and lack cyano groups at the ends. Therefore, compared to the products of Comparative Examples 4, 5, 7, and 8, they exhibit lower loss tangent and superior dielectric properties. Moreover, the products of Examples 1 to 13 can form sufficiently independent sheets even without the use of thermoplastic resins or crosslinking agents, thus demonstrating excellent formability.

[0182] Comparing Examples 1 to 5 using the polymerization initiator of Formula (1) and Examples 6 to 13 using the polymerization initiator of Formula (2), Examples 1 to 5 tend to have lower loss tangents. This is believed to be because the polymerization initiator of Formula (2) introduces an ether bond at the end, while no heteroatom is introduced in Formula (1).

[0183] Furthermore, the various numerical ranges described in the specification can be any combination of the upper and lower limits, and all such combinations are described in this specification as preferred numerical ranges. Also, the description of the numerical range "X to Y" refers to X above and Y below.

[0184] The above description illustrates several embodiments of the present invention, but these embodiments are merely illustrative and 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 scope of the invention's intent. If these embodiments, or their omissions, substitutions, or modifications, are included within the scope or intent of the invention, they are similarly included within the scope of the invention described in the claims of this invention and their equivalents.

Claims

1. A thermosetting resin, which is a linear vinyl copolymer having repeating units corresponding to monovinyl aromatic compounds and repeating units corresponding to divinyl aromatic compounds, wherein the content of the repeating units corresponding to divinyl aromatic compounds is 5.0 to 25.0 mol%, and the ends of the linear vinyl copolymer have at least one of R1- and / or R2- derived from the polymerization initiator shown in general formula (1): R1-N=N-R2, or R3O- and / or R4O- derived from the polymerization initiator shown in general formula (2): R3-OO-R4, wherein R1, R2, R3 and R4 in general formulas (1) and (2) independently represent a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group.

2. The thermosetting resin as claimed in claim 1, having the following structure: a copolymer obtained by copolymerizing a vinyl benzyl phosphonium salt with a monovinyl aromatic compound using at least one of the polymerization initiators of the aforementioned general formula (1) or the aforementioned general formula (2), and then reacting the copolymer with formaldehyde to obtain the following structure.

3. The thermosetting resin as claimed in claim 1 or 2, which is a random copolymer having repeating units corresponding to the aforementioned monovinyl aromatic compounds and repeating units corresponding to the aforementioned divinyl aromatic compounds.

4. The thermosetting resin as described in claim 1 or 2, wherein the number average molecular weight Mn and the weight average molecular weight Mw are 3,000 or more and less than 100,000.

5. A cured material formed by curing with a thermosetting resin as described in any one of claims 1 to 4.

6. A thermosetting composition comprising a thermosetting resin as described in any one of claims 1 to 4.

7. The thermosetting composition as described in claim 6 is a printed circuit board material.

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