KR20230070409A - Thermosetting resins and cured products thereof - Google Patents

Abstract

A thermosetting resin from which a cured product having excellent dielectric properties is obtained. The thermosetting resin according to the embodiment has a repeating unit corresponding to a monovinyl aromatic compound and a repeating unit corresponding to a divinyl aromatic compound, and has a number average molecular weight (Mn) and a weight average molecular weight (Mw) of 10,000 or more and 100,000, respectively. Below, content of the repeating unit corresponding to the said divinyl aromatic compound is 5-20 mol%.

Description

Thermosetting resins and cured products thereof

An embodiment of the present invention relates to a thermosetting resin and a cured product thereof, and also to a thermosetting composition containing the thermosetting resin.

BACKGROUND ART In recent years, miniaturization and performance enhancement of electronic devices have been progressing, and with this, the required performance of various materials used has improved. For example, a printed circuit board material with a low dielectric loss tangent capable of coping with high-frequency communication is required.

Patent Document 1 discloses a vinyl compound obtained by converting the terminal of a bifunctional PPE (polyphenylene ether) oligomer into a vinyl group as a thermosetting resin material having excellent heat resistance and electrical properties.

In Patent Document 2, as a curable resin composition for improving dielectric properties, long-term environmental reliability, heat resistance, and adhesion, 2 to 95 mol% of repeating units derived from divinyl aromatic compounds and 5 to 98 repeating units derived from monovinyl aromatic compounds A curable resin composition comprising a polyfunctional vinyl aromatic copolymer containing mol%, a thermoplastic resin, and a thermosetting crosslinking agent is disclosed.

Japanese Unexamined Patent Publication No. 2004-067727 Japanese Unexamined Patent Publication No. 2019-178310

In Patent Literature 1, a PPE-based resin having a relatively low dielectric loss tangent and good reactivity is used, but the dielectric loss tangent cannot be said to be sufficient. Patent Document 2 discloses a styrenic thermosetting resin, but since the specifically disclosed thermosetting resin has a low number average molecular weight (Mn) and a high content of repeating units derived from divinyl aromatic compounds, it is considered that the dielectric loss tangent is sufficient. was not possible, and cracks occurred due to curing shrinkage, and it was found that moldability deteriorated.

In view of the above points, an object of embodiments of the present invention is to provide a thermosetting resin capable of suppressing deterioration of moldability and from which a cured product having excellent dielectric properties can be obtained.

The present invention includes embodiments shown below.

[1] has a repeating unit corresponding to a monovinyl aromatic compound and a repeating unit corresponding to a divinyl aromatic compound, and has a number average molecular weight (Mn) and a weight average molecular weight (Mw) of 10,000 or more and 100,000 or less, respectively; The thermosetting resin whose content of the repeating unit corresponding to a vinyl aromatic compound is 5-20 mol%.

[2] The thermosetting resin according to [1], which is a linear vinyl copolymer.

[3] The thermosetting resin according to [1] or [2], which is obtained by reacting a copolymer formed by copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound and formaldehyde.

[4] A cured product obtained by curing the thermosetting resin according to any one of [1] to [3].

[5] A thermosetting composition containing the thermosetting resin according to any one of [1] to [3].

[6] The thermosetting composition according to [5], which is a printed circuit board material.

With the thermosetting resin according to the embodiment of the present invention, deterioration of moldability can be suppressed, and a cured product having excellent dielectric properties can be obtained.

The thermosetting resin according to the present embodiment is a vinyl copolymer having a repeating unit corresponding to a monovinyl aromatic compound and a repeating unit corresponding to a divinyl aromatic compound, and has a number average molecular weight (Mn) and a weight average molecular weight (Mw), respectively. It is 10,000 or more and 100,000 or less, and content of the repeating unit corresponding to the said divinyl aromatic compound is 5-20 mol%. According to this embodiment, the dielectric loss tangent of the cured product can be lowered. In addition, since the increase in crosslinking density can be suppressed and the occurrence of cracks due to curing shrinkage can be suppressed, deterioration of moldability can be suppressed.

The repeating unit corresponding to the monovinyl aromatic compound is a structural unit having a structure formed by addition polymerization of a monovinyl aromatic compound as a monomer as a structural unit of the vinyl copolymer, and has a structure corresponding to the monovinyl aromatic compound. , It is not limited to what is necessarily formed by polymerization using the monovinyl aromatic compound, but may be made into a structure corresponding to the monovinyl aromatic compound by further reacting after polymerization.

As the repeating unit corresponding to the monovinyl aromatic compound, as shown in the following general formula (1), a repeating unit having a structure in which the vinyl group of the monovinyl aromatic compound has become a single bond through addition polymerization is exemplified.

[Formula 1]

In formula (1), R ¹ represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and more specifically, a phenyl group which may have a substituent, a biphenyl group which may have a substituent, a naphthyl group which may have a substituent, and a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms selected from the group consisting of a terphenyl group which may have a substituent.

As the monovinyl aromatic compound forming such a repeating unit, any aromatic compound having one vinyl group may be used, and examples thereof include vinyl aromatic compounds such as styrene, vinyl naphthalene, and vinyl biphenyl; alkyl styrene (eg, o- methyl styrene, m-methyl styrene, p-methyl styrene, o-ethyl styrene, m-ethyl styrene, p-ethyl styrene), dialkyl styrene (e.g. 3,5-dimethyl styrene, 2,5-dimethyl styrene, 2,5-diethyl styrene), alkyl vinyl biphenyl (e.g. ethyl vinyl biphenyl), alkyl vinyl naphthalene (e.g. ethyl vinyl naphthalene), and the like; and the like. , These can be used by any one type or in combination of two or more types. Among these, styrene is preferable.

The repeating unit corresponding to the divinyl aromatic compound is a structural unit having a structure formed by addition polymerization of a divinyl aromatic compound as a monomer as a structural unit of a vinyl copolymer, and has a structure corresponding to the divinyl aromatic compound. , It is not limited to what is necessarily formed by polymerization using the divinyl aromatic compound, and may be made into a structure corresponding to the divinyl aromatic compound by further reacting after polymerization.

As the repeating unit corresponding to the divinyl aromatic compound, as shown in the following general formula (2), a repeating unit having a structure in which one vinyl group of the divinyl aromatic compound has become a single bond through addition polymerization is exemplified.

[Formula 2]

In Formula (2), R ² represents a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and more specifically, a phenylene group which may have a substituent, a biphenyldiyl group which may have a substituent, and a substituent which may have and a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms selected from the group consisting of a naphthylene group and a terphenyldiyl group which may have a substituent.

The divinyl aromatic compound forming such a repeating unit may be any aromatic compound having two vinyl groups, and examples thereof include divinylbenzene (including each positional isomer or a mixture thereof), and divinylnaphthalene (each positional isomer). isomers or mixtures thereof) and divinylbiphenyl (including positional isomers or mixtures thereof) are exemplified, and these may be used singly or in combination of two or more thereof. Among these, divinylbenzene (m-isomer, p-isomer or a mixture of positional isomers thereof) is preferable.

In the thermosetting resin according to the present embodiment, the repeating units corresponding to the monovinyl aromatic compound and the repeating units corresponding to the divinyl aromatic compound may be arranged regularly or randomly. Preferably, it is a randomly arranged random copolymer.

Moreover, the thermosetting resin may contain repeating units corresponding to other monomers in addition to the repeating units corresponding to the monovinyl aromatic compound and the repeating units corresponding to the divinyl aromatic compound, within the range in which the effect is not impaired. Examples of such other monomers include trivinyl aromatic compounds, trivinyl aliphatic compounds, divinyl aliphatic compounds, monovinyl aliphatic compounds and the like.

The thermosetting resin according to the present embodiment has a number average molecular weight (Mn) of 10,000 or more and 100,000 or less. When the number average molecular weight (Mn) is 10,000 or more, the concentration of terminal groups derived from the polymerization initiator can be lowered and the dielectric properties can be improved. Moreover, when a number average molecular weight (Mn) is 100,000 or less, viscosity increase at the time of making a thermosetting resin into a solution can be suppressed and handling property can be improved. The number average molecular weight (Mn) is preferably 150,000 or more, more preferably 20,000 or more, and preferably 50,000 or less, more preferably 40,000 or less, still more preferably 30,000 or less. .

The weight average molecular weight (Mw) of the thermosetting resin concerning this embodiment is 10,000 or more and 100,000 or less. When the weight average molecular weight (Mw) is 10,000 or more, the concentration of terminal groups derived from the polymerization initiator can be lowered and the dielectric properties can be improved. Moreover, when a weight average molecular weight (Mw) is 100,000 or less, viscosity increase at the time of making a thermosetting resin into a solution can be suppressed and handling property can be improved. The weight average molecular weight (Mw) is preferably 20,000 or more, more preferably 250,000 or more, still more preferably 30,000 or more, still more preferably 40,000 or more, and preferably 70,000 or less , More preferably, it is 60,000 or less, and still more preferably is 50,000 or less.

In the thermosetting resin according to the present 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 It is 1.2-3.0, More preferably, it is 1.5-1.9.

Here, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are the number average molecular weight and weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

In the thermosetting resin according to the present embodiment, the content of the repeating unit corresponding to the divinyl aromatic compound is 5 to 20 mol%. That is, the content of repeating units corresponding to the divinyl aromatic compound is 5 mol% or more and 20 mol% or less, with the total repeating units constituting the vinyl copolymer being 100 mol%. When the content of the repeating unit corresponding to the divinyl aromatic compound is 5 mol% or more, thermosetting properties are improved and a good cured product can be obtained, and when the content is 20 mol% or less, cracking due to curing shrinkage is suppressed. Thus, formability can be improved. It is preferable that content of the repeating unit corresponding to a divinyl aromatic compound is 7 mol% or more, and it is preferable that it is 15 mol% or less.

In the thermosetting resin according to the present embodiment, the content of the repeating unit corresponding to the monovinyl aromatic compound is preferably 80 to 95 mol% based on 100 mol% of all repeating units constituting the vinyl copolymer. It is preferable that content of the repeating unit corresponding to a monovinyl aromatic compound is 85 mol% or more, and it is preferable that it is 93 mol% or less.

The method for producing the thermosetting resin according to the present embodiment is not particularly limited, and can be obtained by, for example, polymerizing a monomer containing a monovinyl aromatic compound and a divinyl aromatic compound in the presence of a polymerization initiator.

As a preferred production method, a method of obtaining a thermosetting resin by copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound and reacting the resulting copolymer with formaldehyde is exemplified. Since it is possible to synthesize a straight-chain vinyl copolymer having no branch as a thermosetting resin, the dielectric properties can be improved by lowering the concentration of terminal groups derived from the polymerization initiator. In addition, due to the linear structure, entangling of the molecular chains is caused to improve formability.

As a phosphonium group in the said vinylbenzylphosphonium halide, tertiary phosphonium groups, such as a trialkyl phosphonium group, a triaryl phosphonium group, and a triaralkyl phosphonium group, are mentioned, for example. Moreover, as a halogen which forms a salt with a phosphonium group, chlorine, bromine, etc. are mentioned, for example.

As a method for copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound, a known vinyl polymerization method can be used and is not particularly limited. For example, by copolymerizing using an azo compound such as azobisisobutyronitrile (AIBN) or a radical polymerization initiator such as an organic peroxide such as benzoyl peroxide, a repeating unit derived from vinylbenzylphosphonium halide and a monovinyl aromatic compound A copolymer having repeating units derived from is obtained.

And, as a method of reacting the obtained copolymer with formaldehyde, a known Wittig reaction can be used, and the copolymer is treated with a base and reacted with formaldehyde to remove a phosphonium group and introduce a vinyl group.

According to this production method, since the vinylbenzylphosphonium halide is monovinyl in the copolymerization step, a copolymer having no branch is obtained, and after copolymerization, a vinyl group is introduced into a repeating unit derived from the vinylbenzylphosphonium halide. A linear vinyl copolymer having repeating units corresponding to aromatic compounds and having no branches can be obtained.

The thermosetting composition according to the present embodiment contains the thermosetting resin. The content of the thermosetting resin in the thermosetting composition is not particularly limited as long as the composition has a property to be cured by heat. For example, 1 to 99 mass% with respect to 100% by mass of the solid content of the thermosetting composition (the amount excluding the organic solvent when the organic solvent described later is included, and the total amount of the composition when the organic solvent is not included) It may be 10% or 10 to 95% by mass.

In the thermosetting composition, in addition to the thermosetting resin, for example, other thermosetting resins (thermosetting crosslinking agents), thermoplastic resins, fillers, flame retardants, curing accelerators, polymerization initiators, antifoaming agents, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes and pigments, etc. You may contain various components, such as a coloring agent, a lubricant, and a dispersing agent.

Moreover, the thermosetting composition may contain an organic solvent in order to adjust the viscosity, and the thermosetting composition may be a solution containing the above thermosetting resin. As the organic solvent, one capable of dissolving the thermosetting resin is used, and examples thereof include ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, propyl acetate and butyl acetate, dimethylacetamide, Amides, such as dimethylformamide, and aromatic hydrocarbons, such as toluene and xylene, etc. are mentioned, Any 1 type or a combination of 2 or more types of these can be used.

Since the thermosetting resin or thermosetting composition of the present embodiment has a vinyl group in the molecular chain of the vinyl copolymer, crosslinking by polymerization is possible, and a cured product can be obtained by thermosetting. Since the cured product has a low dielectric loss tangent and excellent dielectric properties, it can be used for electronic materials such as printed circuit board materials and semiconductor encapsulation materials.

Examples of the printed board material include rigid printed board materials such as single-sided board, double-sided board, multi-layer board, and build-up board, film-form or sheet-form flexible printed board material, and the like. In addition, since the dielectric loss tangent is low, it is preferably used as a high-frequency substrate material used in high-frequency communication devices.

Example

Hereinafter, it will be described more specifically by examples, but the present invention is not limited to the following examples.

<Measurement/evaluation method>

[Styrene/divinylbenzene molar ratio, divinylbenzene ratio]

The products obtained in Examples 1 and 2 and Comparative Examples 1 and 3 were dissolved in deuterated chloroform and subjected to ¹ H-NMR measurement with a nuclear magnetic resonance apparatus (manufactured by JEOL) to determine whether repeating units corresponding to styrene and The molar ratio of repeating units corresponding to vinylbenzene was determined, and the content of repeating units corresponding to styrene (styrene ratio) and the content of repeating units corresponding to divinylbenzene (divinylbenzene ratio) with respect to 100 mol% of all repeating units were calculated. Calculated.

[Number average molecular weight, weight average molecular weight]

The products obtained in Examples 1 and 2 and Comparative Examples 1 and 4 were dissolved in tetrahydrofuran, and four columns (Shodex GPC columns KF-601, KF-602, KF-603, KF-603, KF- 604, Showa Denko make) was connected, and the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were measured by gel permeation chromatography (GPC) (Prominence, manufactured by Shimadzu Corporation). A differential refractive index detector (Shodex RI-504, manufactured by Showa Denko) was used at a column oven temperature of 40°C and a THF flow rate of 0.6 mL/min.

[Permittivity, dielectric loss tangent]

The products obtained in Examples 1 to 2 and Comparative Examples 1 to 4 were used as samples. Using a single acting compression molding machine for testing (manufactured by Yasuda Seiki Seisakusho), 1.5 g of the sample was pressed at a pressure of 10 Pa and a temperature of 220°C for 15 minutes to prepare a flat plate of 30 mm x 30 mm x 1 mm in thickness. The obtained flat plate was cut to prepare a test piece having a width of 2 mm, a thickness of 1 mm, and a length of 30 mm, and the dielectric constant and dielectric loss tangent at 10 GHz were measured using a cavity resonance method permittivity measuring device (manufactured by KEYSIGHT). .

[thermosetting]

The products obtained in Examples 1 and 2 and Comparative Examples 1 and 4 were used as samples and heated from room temperature to 350°C at a heating rate of 10°C/min using a differential scanning calorimeter (manufactured by Rigaku). Those with an exothermic peak calorific value of 40 J/g or more were rated "◎" (good thermosetting properties), those of 20 to 40 J/g were rated "○", and those with a calorific value of less than 20 J/g were rated "x" (poor thermosetting properties).

[Formability]

Using the products obtained in Examples 1 and 2 and Comparative Examples 1 and 4 as samples, 7.0 g of the sample was pressed for 10 minutes at a pressure of 10 Pa and a temperature of 220 ° C. using a single-acting compression molding machine (manufactured by Yasuda Seiki Seisakusho) for testing, 110 A self-supporting board having a thickness of mm × 60 mm × 1 mm was obtained as "○" (good moldability), and a case in which a self-supporting board was not obtained due to breakage of the cured product was evaluated as "x" (poor moldability).

(Synthesis Example 1) Compound 1: Synthesis of Triphenylvinylbenzylphosphonium Chloride 1.5 mol (228.9 g) of vinylbenzyl chloride (trade name: CMS-14, manufactured by AGC Semi Chemical), 1.8 mol of triphenylphosphine (472.1 g) ) and 622.4 g of dimethylformamide were introduced into a 2.0 L reactor and reacted at 70°C for 3 hours under nitrogen conditions to precipitate a white solid. After sufficiently washing the solid with acetone, it was dried under reduced pressure at 92°C to recover 490 g of compound 1.

(Synthesis Example 2) Synthesis of Copolymer A

552.12 g of styrene, 169.2 g of Compound 1, 3.27 g of azobisisobutyronitrile, and 1682.68 g of dimethylformamide were charged into a 3.0 L reactor, and reacted at 70°C for 9 hours under nitrogen conditions. After concentrating this reaction solution under reduced pressure, it was dissolved in dichloromethane and reprecipitated in a large excess of isopropyl alcohol. Then, the supernatant was decanted and 285.0 g of copolymer A was recovered by drying the remaining solid at 92°C under reduced pressure.

(Synthesis Example 3) Synthesis of Copolymer B

110 g of styrene, 62.6 g of Compound 1, 0.78 g of azobisisobutyronitrile, and 258.9 g of dimethylformamide were put into a 1.0 L reactor, and reacted under nitrogen conditions at 70°C for 9 hours to obtain copolymer B Obtained as a dimethylformamide solution.

(Comparative Synthesis Example 1) Synthesis of Copolymer C

1.37 mol (142.7 g) of styrene, 0.051 mol (21.2 g) of Compound 1, 0.75 g of azobisisobutyronitrile, and 245.9 g of dimethylformamide were charged into a 1.0 L reactor, and 9 g at 70° C. under nitrogen conditions. time reacted. After concentrating this reaction solution under reduced pressure, it was dissolved in dichloromethane and reprecipitated in a large excess of isopropyl alcohol. Subsequently, the supernatant was decanted and 102.4 g of copolymer C was recovered by drying the remaining solid under reduced pressure at 92°C.

(Comparative Synthesis Example 2) Synthesis of Copolymer D

0.53 mol (55.2 g) of styrene, 0.041 mol (16.9 g) of Compound 1, 3.24 g of azobisisobutyronitrile, and 108.17 g of dimethylformamide were charged into a 500 mL reactor, and 5 It was made to react for an hour, and copolymer D was obtained as a dimethylformamide solution.

(Comparative Synthesis Example 3) Synthesis of Copolymer E

0.48 mol (50.2 g) of styrene, 0.12 mol (50.0 g) of Compound 1, 0.45 g of azobisisobutyronitrile, and 186.09 g of dimethylformamide were charged into a 500 mL reactor, and the mixture was stirred at 8 °C at 68°C under nitrogen conditions. It was allowed to react for half an hour to obtain copolymer E as a dimethylformamide solution.

(Example 1)

285.0 g of copolymer A obtained in Synthesis Example 2, 169.83 g of 37% formalin, 209.66 g of 28% potassium hydroxide aqueous solution, and 665.0 g of tetrahydrofuran were put into a 3 L reactor and reacted at room temperature for 4 hours. The reaction solution was reprecipitated in a large excess of methanol, solid was taken out by filtration, dissolved in dichloromethane, and the organic layer was washed with distilled water to reprecipitate with a large excess of methanol/water = 7/3. After taking out solid by filtration then, product 1 was collect|recovered by drying under reduced pressure at 92 degreeC. The Mn of Product 1 was 24700, the Mw was 39800, the styrene ratio was 92.1 mol%, and the divinylbenzene ratio was 7.9 mol%.

(Example 2)

20 g of the dimethylformamide solution of the copolymer B obtained in Synthesis Example 3, 3.8 g of 37% formalin, 9.4 g of 28% potassium hydroxide aqueous solution, and 24 g of dimethylformamide were put into a 50 mL reactor and held at room temperature for 1 hour. reacted The precipitated solid was dissolved in dichloromethane, reprecipitated in isopropyl alcohol, and the solid was taken out by filtration. It was dissolved in dichloromethane again, and the organic layer was washed with distilled water to reprecipitate with methanol/water = 7/3. Subsequently, after taking out the solid by filtration, product 2 was recovered by drying under reduced pressure at 92°C. Mn of product 2 was 26600, Mw was 48900, the styrene ratio was 85.3 mol%, and the divinylbenzene ratio was 14.7 mol%.

(Comparative Example 1)

6.00 g of copolymer C obtained in Comparative Synthesis Example 1, 5.47 g of 37% formalin, 6.00 g of 28% potassium hydroxide aqueous solution, and 150 g of tetrahydrofuran were put into a 500 mL reactor and reacted at room temperature for 4 hours. After re-precipitating the reaction solution in methanol and taking out solids by filtration, product 3 was recovered by drying under reduced pressure at 92°C. Mn of product 3 was 24300, Mw was 39200, the styrene ratio was 95.7 mol%, and the divinylbenzene ratio was 4.3 mol%.

(Comparative Example 2)

29.7 g of the dimethylformamide solution of copolymer D obtained in Comparative Synthesis Example 2, 6.1 g of 37% formalin, 7.6 g of 28% aqueous potassium hydroxide solution, and 70 g of tetrahydrofuran were put into a 300 mL reactor, and reacted half an hour. The reaction solution was reprecipitated in methanol, solid was taken out by filtration, dissolved in dichloromethane, and the organic layer was washed with distilled water, followed by reprecipitation in methanol/water = 7/3. Subsequently, after taking out the solid by filtration, product 4 was recovered by drying under reduced pressure at 92°C. The Mn of Product 4 was 3400, the Mw was 8400, the styrene ratio was 91.9 mol%, and the divinylbenzene ratio was 8.1 mol%.

(Comparative Example 3)

280.0 g of the dimethylformamide solution of the copolymer E obtained in Comparative Synthesis Example 3, 48.5 g of 37% formalin, 59.5 g of 28% aqueous potassium hydroxide solution, and 93.8 g of tetrahydrofuran were charged into a 1 L reactor and maintained at room temperature for 7 hours. reacted After adding dichloromethane to the reaction solution, it was reprecipitated in methanol, and after taking out the solid by filtration, it was dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated in methanol/water = 7/3. Subsequently, after taking out the solid by filtration, product 5 was recovered by drying under reduced pressure at 92°C. Mn of Product 5 was 24200, Mw was 43300, the styrene ratio was 75.0 mol%, and the divinylbenzene ratio was 25.0 mol%.

(Comparative Example 4) Synthesis of vinylbenzylated polyphenylene ether compound

158 g (0.1 mol) of reactive low molecular weight polyphenylene ether (trade name: Noryl SA-90, manufactured by SABIC Japan Co., Ltd.) was placed in a 2 L four-necked flask equipped with a temperature controller, stirring device, cooling condenser, and dropping funnel, 221 g of toluene and 94.8 g of isopropyl alcohol were injected to obtain a homogeneous solution, followed by 0.96 g of tetra-n-butylammonium bromide and vinylbenzyl chloride (meta/para-a = 50/50, trade name: CMSP, AGC Semichemical Co., Ltd.) 33.6 g (0.22 mol) was added, and it heated up to 75 degreeC. Here, 53.3 g (0.64 mol) of 48% sodium hydroxide aqueous solution was added dropwise over 30 minutes in 1/4 amounts every 2 hours, and as a result of reacting at 75°C for a total of 8 hours, the reaction rate was 98% or more. Then, it cooled to 50 degreeC, 295 g of toluene, 31.6 g of isopropanol, and 79 g of water were added, and it neutralized with 66.7 g of 35 mass % hydrochloric acid aqueous solution. It was allowed to stand until the reaction solution was separated into two layers, and the lower aqueous solution layer was removed. Further, washing with 15.8 g of isopropanol and 63.2 g of water was performed 5 times. The organic layer was dehydrated at 70°C and 50 mmHg until it became 0.05% or less, and the solution was filtered again to obtain 345 g of a 50% toluene solution of a vinylbenzylated polyphenylene ether compound (based on polyphenylene ether). yield 95%) was obtained. This solution was re-precipitated in a large excess of methanol, and the solid taken out by filtration was dried at 92°C under reduced pressure. The number average molecular weight of the obtained vinylbenzylated polyphenylene ether compound was 2200, and the weight average molecular weight was 4000.

The products obtained in Examples 1 to 2 and Comparative Examples 1 to 4 were evaluated for dielectric constant, dielectric loss tangent, thermosetting property and moldability. The results are shown in Table 1 and Table 2 below.

As shown in Table 1, in Comparative Example 1, the divinylbenzene ratio was low and the thermosetting property was insufficient, so that a test piece for dielectric constant and dielectric loss tangent evaluation could not be produced. Therefore, the dielectric constant and dielectric loss tangent are not measured, and moldability is not evaluated.

In Comparative Example 2, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were small, so the dielectric loss tangent was greatly inferior. Further, since the result of the dielectric loss tangent was poor, evaluation of moldability was not performed.

In Comparative Example 3, the divinylbenzene ratio was high, and therefore the dielectric loss tangent was poor due to the remaining unreacted vinyl groups. In addition, the test piece for dielectric constant and dielectric loss tangent evaluation was able to be molded, but cracks occurred in the test piece and moldability was poor in moldability evaluation with a large size of the test piece. It is thought that since the number of functional groups is large, curing shrinkage occurs and the formability is lowered.

On the other hand, in Comparative Example 4, which is a PPE-based thermosetting resin, the dielectric loss tangent was high and the dielectric properties were poor.

On the other hand, in Examples 1 and 2, in which the number average molecular weight (Mn) and the weight average molecular weight (Mw) are within the specified range and the divinylbenzene ratio is within the specified range, the self-sustaining grade was obtained without the use of a thermoplastic resin or a crosslinking agent in combination. A sufficient sheet could be molded, and while being excellent in formability, the dielectric loss tangent was low and the dielectric properties were excellent compared to the PPE-based thermosetting resin of Comparative Example 4.

As mentioned above, several embodiments of the present invention have been described, but 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 changes can be made within a range not departing from the gist of the invention. These embodiments and their omissions, substitutions, changes, etc., if included in the scope and gist of the invention, are equally included in the invention described in the claims and their equivalents.

Claims (6)

It has a repeating unit corresponding to a monovinyl aromatic compound and a repeating unit corresponding to a divinyl aromatic compound, and has a number average molecular weight (Mn) and a weight average molecular weight (Mw) of 10,000 or more and 100,000 or less, respectively, and the divinyl aromatic compound A thermosetting resin in which the content of the repeating unit corresponding to is 5 to 20 mol%. According to claim 1,
A thermosetting resin that is a linear vinyl copolymer. According to claim 1 or 2,
A thermosetting resin obtained by reacting a copolymer obtained by copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound and formaldehyde. A cured product formed by curing the thermosetting resin according to any one of claims 1 to 3. A thermosetting composition comprising the thermosetting resin according to any one of claims 1 to 3. According to claim 5,
A thermosetting composition that is a printed circuit board material.