JP2022052522A - Thermosetting resin and cured product thereof - Google Patents

Abstract

To provide a thermosetting resin which gives a cured product having excellent dielectric characteristics.SOLUTION: The thermosetting resin according to an embodiment comprises a repeating unit corresponding to a monovinyl aromatic compound and a repeating unit corresponding to a divinyl aromatic compound. The number average molecular weight Mn and the weight average molecular weight Mw of the thermosetting resin are 10,000 or more and 100,000 or less, respectively. The content of the repeating unit corresponding to the divinyl aromatic compound is 5-20 mol%.SELECTED DRAWING: None

Description

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.

In recent years, the miniaturization and high performance of electronic devices have been progressing, and along with this, the required performance of various materials used has been improved. For example, there is a demand for a printed circuit board material having a low dielectric loss tangent that can be used for high-frequency communication.

Patent Document 1 discloses a vinyl compound in which the end of a bifunctional PPE (polyphenylene ether) oligomer is converted into a vinyl group as a thermosetting resin material having excellent heat resistance and electrical properties.

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

Japanese Unexamined Patent Publication No. 2004-06727 Japanese Unexamined Patent Publication No. 2019-178310

In Patent Document 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 styrene-based thermosetting resin, but the specifically disclosed thermosetting resin has a low number average molecular weight Mn and a content of repeating units derived from a divinyl aromatic compound. Since it is high, it cannot be said that the dielectric loss tangent is sufficient, and it has been found that cracking due to curing shrinkage occurs and the moldability deteriorates.

In view of the above points, it is an object of the present invention to provide a thermosetting resin capable of suppressing deterioration of moldability and obtaining a cured product having excellent dielectric properties.

The present invention includes embodiments shown below.
[1] 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 having a repeating unit content of 5 to 20 mol% corresponding to the compound.
[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 obtained by copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound with 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. Each is 10,000 or more and 100,000 or less, and the content of the repeating unit corresponding to the divinyl aromatic compound is 5 to 20 mol%. According to this embodiment, the dielectric loss tangent of the cured product can be lowered. In addition, it is possible to suppress an increase in the crosslink density and suppress the occurrence of cracks due to curing shrinkage, so that deterioration of moldability can be suppressed.

The repeating unit corresponding to the monovinyl aromatic compound is a structural unit of the vinyl copolymer and has a structure formed by addition polymerization of the monovinyl aromatic compound as a monomer. As long as it has a structure corresponding to the compound, it is not necessarily limited to the one obtained by polymerization using the monovinyl aromatic compound, and the structure corresponding to the monovinyl aromatic compound is obtained by further reacting after the polymerization. But it may be.

Examples of the repeating unit corresponding to the monovinyl aromatic compound include a repeating unit having a structure in which the vinyl group of the monovinyl aromatic compound is single-bonded by addition polymerization as represented by the following general formula (1).

In the formula (1), R ¹ represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and more specifically, it has a phenyl group and a substituent which may have a substituent. A monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms selected from the group consisting of a good biphenyl group, a naphthyl group which may have a substituent, and a turphenyl group which may have a substituent. Can be mentioned.

The monovinyl aromatic compound forming such a repeating unit may be any aromatic compound having one vinyl group, for example, vinyl aromatic compounds such as styrene, vinylnaphthalene and vinylbiphenyl, and alkylstyrene (for example, o). -Methyl styrene, m-methyl styrene, p-methyl styrene, o-ethyl styrene, m-ethyl styrene, p-ethyl styrene), dialkyl styrene (eg 3,5-dimethyl styrene, 2,5-dimethyl styrene, 2) , 5-Diethylstyrene), alkyl vinyl biphenyl (eg ethyl vinyl biphenyl), nuclear alkyl substituted vinyl aromatic compounds such as alkyl vinyl naphthalene (eg ethyl vinyl naphthalene), etc., any one or more. Can be used in combination. Of these, styrene is preferable.

The repeating unit corresponding to the divinyl aromatic compound is a structural unit of the vinyl copolymer, which has a structure formed by addition polymerization of the divinyl aromatic compound as a monomer, and is the divinyl aromatic compound. As long as it has a structure corresponding to the compound, it is not necessarily limited to the one obtained by polymerizing using the divinyl aromatic compound, and the structure corresponding to the divinyl aromatic compound is obtained by further reacting after the polymerization. But it may be.

Examples of the repeating unit corresponding to the divinyl aromatic compound include a repeating unit having a structure in which one vinyl group of the divinyl aromatic compound is single-bonded by addition polymerization as represented by the following general formula (2). ..

In the formula (2), R ² represents a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and more specifically, it has a phenylene group and a substituent which may have a substituent. A divalent aromatic carbide having 6 to 30 carbon atoms selected from the group consisting of a good biphenyldiyl group, a naphthylene group which may have a substituent, and a turphenyldiyl group which may have a substituent. A hydrogen group can be mentioned.

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

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

Further, in the thermosetting resin, in addition to the repeating unit corresponding to the monovinyl aromatic compound and the repeating unit corresponding to the divinyl aromatic compound, the repeating unit corresponding to other monomers is used as long as the effect is not impaired. It may be included. 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 this 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 the terminal group derived from the polymerization initiator can be lowered and the dielectric property can be improved. Further, when the number average molecular weight Mn is 100,000 or less, it is possible to suppress the increase in viscosity when the thermosetting resin is used as a solution and improve the handleability. The number average molecular weight Mn is preferably 15,000 or more, more preferably 20,000 or more, preferably 50,000 or less, more preferably 40,000 or less, still more preferably 3. It is less than 10,000.

The thermosetting resin according to this embodiment has a weight average molecular weight Mw of 10,000 or more and 100,000 or less. When the weight average molecular weight Mw is 10,000 or more, the concentration of the terminal group derived from the polymerization initiator can be lowered and the dielectric property can be improved. Further, when the weight average molecular weight Mw is 100,000 or less, it is possible to suppress the increase in viscosity when the thermosetting resin is used as a solution and improve the handleability. The weight average molecular weight Mw is preferably 20,000 or more, more preferably 25,000 or more, still more preferably 30,000 or more, still more preferably 40,000 or more, and 70,000 or less. It is preferably 60,000 or less, still more preferably 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 1. It is .2 to 3.0, more preferably 1.5 to 1.9.

Here, the number average molecular weight Mn and the weight average molecular weight Mw are polystyrene-equivalent number average molecular weight and weight average molecular weight 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 the repeating unit corresponding to the divinyl aromatic compound is 5 mol% or more and 20 mol% or less, assuming that all the repeating units constituting the vinyl copolymer are 100 mol%. When the content of the repeating unit corresponding to the divinyl aromatic compound is 5 mol% or more, the thermosetting property can be enhanced to obtain a good cured product, and the content is 20 mol% or less. As a result, it is possible to suppress the occurrence of cracks due to curing shrinkage and improve the moldability. The content of the repeating unit corresponding to the divinyl aromatic compound is preferably 7 mol% or more, and preferably 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 80 to 95 mol%, where 100 mol% is the total repeating unit constituting the vinyl copolymer. preferable. The content of the repeating unit corresponding to the monovinyl aromatic compound is preferably 85 mol% or more, and preferably 93 mol% or less.

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

As a preferable production method, a method of copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound and reacting the obtained copolymer with formaldehyde to obtain a thermosetting resin can be mentioned. As a result, a linear vinyl copolymer having no branch can be synthesized as a thermosetting resin, so that the concentration of the terminal group derived from the polymerization initiator can be lowered and the dielectric property can be improved. In addition, the linear structure causes entanglement of molecular chains to improve moldability.

Examples of the phosphonium group in the vinylbenzyl phosphonium halide include a quaternary phosphonium group such as trialkylphosphonium, triarylphosphonium, and triaralkylphosphonium. Examples of the halogen that forms a salt with a phosphonium group include chlorine and bromine.

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 with 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 can be used. A copolymer having a repeating unit derived from a monovinyl aromatic compound can be obtained.

As a method for reacting the obtained copolymer with formaldehyde, a known Wittig reaction can be used. By treating the copolymer with a base and reacting with formaldehyde, the phosphonium group is removed and vinyl is removed. The group is introduced.

In this production method, since vinylbenzylphosphonium halide is monovinyl in the copolymerization step, a copolymer having no branch can be obtained, and a vinyl group is introduced into a repeating unit derived from vinylbenzylphosphonium halide after the copolymerization. Therefore, it is possible to obtain a linear vinyl copolymer having no branch while having a repeating unit corresponding to the divinyl aromatic compound.

The thermosetting composition according to the present embodiment contains the above-mentioned thermosetting resin. The content of the thermosetting resin in the thermosetting composition is not particularly limited as long as the composition has a property of being heat-curable. For example, 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 contained, and the total amount of the composition when the organic solvent is not contained). It may be 1 to 99% by mass, or 10 to 95% by mass.

In addition to the above thermosetting resin, the thermosetting composition includes, for example, other thermosetting resins (thermosetting cross-linking agents), thermoplastic resins, fillers, flame retardants, curing accelerators, and polymerization initiators. , Antifoaming agent, heat stabilizer, antistatic agent, ultraviolet absorber, colorant such as dye and pigment, lubricant, dispersant and the like may be contained.

Further, the thermosetting composition may contain an organic solvent in order to adjust its viscosity, and the thermosetting composition may be a solution containing the thermosetting resin. As the organic solvent, a solvent capable of dissolving the above-mentioned thermosetting resin is used, for example, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, propyl acetate and butyl acetate, dimethylacetamide and dimethyl. Examples thereof include amides such as formamide, aromatic hydrocarbons such as toluene and xylene, and any one of these or a combination of two or more thereof can be used.

Since the thermosetting resin or the thermosetting composition of the present embodiment has a vinyl group in the molecular chain of the vinyl copolymer, it can be crosslinked by polymerization, 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 circuit board material include a rigid printed circuit board material such as a single-sided substrate, a double-sided substrate, a multilayer substrate, and a build-up substrate, and a film-shaped or sheet-shaped flexible printed circuit board material. Further, since it has a low dielectric loss tangent, it is suitably used as a high-frequency substrate material used in high-frequency communication equipment.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Measurement / evaluation method>
[Mole ratio of styrene / divinylbenzene, divinylbenzene ratio]
The products obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were dissolved in dehydrided chloroform, and ¹ H-NMR measurement was carried out with a nuclear magnetic resonance apparatus (manufactured by JEOL) to obtain a repeating unit corresponding to styrene. Obtain the molar ratio of the repeating unit corresponding to divinylbenzene, and determine the content of the repeating unit corresponding to styrene (styrene ratio) and the content of the repeating unit corresponding to divinylbenzene (divinylbenzene ratio) with respect to 100 mol% of all repeating units. Calculated.

[Number average molecular weight, weight average molecular weight]
Four columns (Shodex GPC columns KF-601, KF-602, KF-603, in which the products obtained in Examples 1 and 2 and Comparative Examples 1 to 4 were dissolved in tetrahydrofuran and the polystyrene gel was used as a filler. The polystyrene-equivalent number average molecular weight Mn and weight average molecular weight Mw were measured by gel permeation chromatography (GPC) (Prominence, manufactured by Shimadzu Corporation) in which KF-604 (manufactured by Showa Denko) was linked. The column oven temperature was 40 ° C., the THF flow rate was 0.6 mL / min, and a differential refractive index detector (Shodex RI-504, manufactured by Showa Denko) was used.

[Permittivity, dielectric loss tangent]
The products obtained in Examples 1 and 2 and Comparative Examples 1 and 4 were used as samples. Using a single-acting compression molding machine for testing (manufactured by Yasuda Seiki Seisakusho), 1.5 g of a sample was pressed at a pressure of 10 Pa and a temperature of 220 ° C. for 15 minutes to prepare a flat plate having a thickness of 30 mm × 30 mm × a thickness of 1 mm. The obtained flat plate is cut to prepare a test piece having a width of 2 mm, a thickness of 1 mm, and a length of 30 mm. Was measured.

[Thermosetting]
Using the products obtained in Examples 1 and 2 and Comparative Examples 1 to 4 as samples, the temperature was raised from room temperature to 350 ° C. using a differential scanning calorimetry device (manufactured by Rigaku) at a heating rate of 10 ° C./min. Those with a heat generation peak of 40 J / g or more are "◎" (good thermosetting), those with a heat generation peak of 20 to 40 J / g are "○", and those with a calorific value of less than 20 J / g are "x" (poor thermosetting). ).

[Formability]
Using the products obtained in Examples 1 and 2 and Comparative Examples 1 to 4 as samples, 7.0 g of the sample was applied for 10 minutes at a pressure of 10 Pa and a temperature of 220 ° C. using a single-acting compression molding machine for testing (manufactured by Yasuda Seiki Seisakusho). Pressing to obtain a self-supporting plate of 110 mm x 60 mm x 1 mm thickness is "○" (good formability), and the one for which a self-supporting plate could not be obtained due to breakage of the cured product is "x" (molding). (Poor sex).

(Synthesis Example 1) Compound 1: Synthesis of triphenylvinylbenzylphosphonium chloride Vinyl benzyl chloride (trade name: CMS-14, manufactured by AGC Seimi Chemical Co., Ltd.) 1.5 mol (228.9 g), triphenylphosphine 1.8 mol (472.1 g) and 622.4 g of dimethylformamide were placed in a 2.0 L reactor and reacted at 70 ° C. for 3 hours under nitrogen conditions to precipitate a white solid. The solid was thoroughly washed with acetone and then 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 put into a 3.0 L reactor. Then, the reaction was carried out at 70 ° C. for 9 hours under nitrogen conditions. The reaction solution was concentrated under reduced pressure, then dissolved in dichloromethane and reprecipitated in a large excess of isopropyl alcohol. Next, the supernatant was decanted, and the remaining solid was dried under reduced pressure at 92 ° C. to recover 285.0 g of the copolymer A.

(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. The reaction was carried out at 70 ° C. for 9 hours under nitrogen conditions to obtain the copolymer B 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 dimethylformamide 245. .9 g was placed in a 1.0 L reactor and reacted at 70 ° C. for 9 hours under nitrogen conditions. The reaction solution was concentrated under reduced pressure, then dissolved in dichloromethane and reprecipitated in a large excess of isopropyl alcohol. Next, the supernatant was decanted, and the remaining solid was dried under reduced pressure at 92 ° C. to recover 102.4 g of the copolymer 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 of dimethylformamide 108. .17 g was placed in a 500 mL reactor and reacted at 70 ° C. for 5 hours under nitrogen conditions to obtain copolymer D 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 dimethylformamide 186. .09 g was put into a 500 mL reactor and reacted at 68 ° C. for 8 and a half hours under nitrogen conditions to obtain copolymer E as a dimethylformamide solution.

(Example 1)
285.0 g of the copolymer A obtained in Synthesis Example 2, 37% formalin 169.83 g, 28% potassium hydroxide aqueous solution 209.66 g, and tetrahydrofuran 665.0 g were put into a 3 L reactor at room temperature. Was reacted for 4 hours. The reaction solution was reprecipitated in a large excess of methanol, the solid was removed by filtration, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated to a large excess of methanol / water = 7/3. Then, after taking out the solid by filtration, the product 1 was recovered by drying under reduced pressure at 92 ° C. The Mn of the 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 the 28% potassium hydroxide aqueous solution, and 24 g of the dimethylformamide were placed in a 50 mL reactor at room temperature. Was reacted for 1 hour. The precipitated solid was dissolved in dichloromethane, reprecipitated in isopropyl alcohol, and the solid was removed by filtration. It was dissolved in dichloromethane again, the organic layer was washed with distilled water, and reprecipitated to methanol / water = 7/3. Then, after taking out the solid by filtration, the product 2 was recovered by drying under reduced pressure at 92 ° C. The Mn of the product 2 was 26600, the 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 the copolymer C obtained in Comparative Synthesis Example 1, 5.47 g of 37% formalin, 6.00 g of a 28% potassium hydroxide aqueous solution, and 150 g of tetrahydrofuran were placed in a 500 mL reactor at room temperature. The reaction was carried out for 4 hours. The reaction solution was reprecipitated in methanol, the solid was taken out by filtration, and then dried under reduced pressure at 92 ° C. to recover the product 3. The Mn of the product 3 was 24300, the 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 the copolymer D obtained in Comparative Synthesis Example 2, 6.1 g of 37% formalin, 7.6 g of the 28% potassium hydroxide aqueous solution, and 70 g of tetrahydrofuran were placed in a 300 mL reactor. , The reaction was carried out at room temperature for two and a half hours. The reaction solution was reprecipitated in methanol, the solid was taken out by filtration, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated to methanol / water = 7/3. Then, the solid was taken out by filtration and then dried under reduced pressure at 92 ° C. to recover the product 4. The Mn of the 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 the 28% potassium hydroxide aqueous solution, and 93.8 g of tetrahydrofuran were put into a 1 L reactor. Then, the reaction was carried out at room temperature for 7 hours. Dichloromethane was added to the reaction solution and then reprecipitated in methanol. The solid was taken out by filtration, dissolved in dichloromethane, the organic layer was washed with distilled water, and reprecipitated to methanol / water = 7/3. Then, the solid was taken out by filtration and then dried under reduced pressure at 92 ° C. to recover the product 5. The Mn of the product 5 was 24200, the Mw was 43300, the styrene ratio was 75.0 mol%, and the divinylbenzene ratio was 25.0 mol%.

(Comparative Example 4) Synthesis of Vinyl Benzylated Polyphenylene Ether Compound Reactive low molecular weight polyphenylene ether (trade name: Noryl SA-90, SABIC) in a 2L four-necked flask equipped with a temperature controller, agitator, cooling condenser, and dropping funnel. 158 g (0.1 mol), 221 g of toluene and 94.8 g of isopropyl alcohol were added to make a uniform solution (manufactured by Japan GK), followed by tetra-n-butylammonium bromide 0.96 g and vinylbenzyl chloride (meth /). Para-form = 50/50, trade name: CMSP, manufactured by AGC Seimi Chemical Co., Ltd.) 33.6 g (0.22 mol) was added, and the temperature was raised to 75 ° C. Here, 53.3 g (0.64 mol) of a 48% sodium hydroxide aqueous solution was added dropwise every 2 hours in a quarter amount over 30 minutes, and the reaction was carried out at 75 ° C. for a total of 8 hours. The reaction rate was increased. Was 98% or more. Then, the mixture was cooled to 50 ° C., 295 g of toluene, 31.6 g of isopropanol and 79 g of water were added, and the mixture was neutralized with 66.7 g of a 35 mass% hydrochloric acid aqueous solution. The reaction solution was allowed to stand until it 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 is removed at 70 ° C. and 50 mmHg until the water content is 0.05% or less, and the solution is further filtered to obtain 345 g of a 50% toluene solution of the vinylbenzylated polyphenylene ether compound (yield 95 based on the polyphenylene ether). %) Was obtained. This solution was reprecipitated in a large excess of methanol, and the solid taken out by filtration was dried under reduced pressure at 92 ° C. The obtained vinyl benzylated polyphenylene ether compound had a number average molecular weight of 2200 and a weight average molecular weight of 4000.

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

As shown in Table 1, in Comparative Example 1, the divinylbenzene ratio was low, the thermosetting property was insufficient, and a test piece for evaluating the dielectric constant and the dielectric loss tangent could not be prepared. Therefore, the permittivity and the dielectric loss tangent are not measured, and the formability is not evaluated.

In Comparative Example 2, the number average molecular weight Mn and the weight average molecular weight Mw were small, and therefore the dielectric loss tangent was significantly inferior. Moreover, since the result of dielectric loss tangent was poor, the moldability was not evaluated.

In Comparative Example 3, the divinylbenzene ratio was high, and therefore the dielectric loss tangent was inferior due to the residual unreacted vinyl group. Further, although the test piece for evaluating the dielectric constant and the dielectric loss tangent could be molded, the test piece was cracked in the formability evaluation in which the size of the test piece was large, and the formability was inferior. It is considered that the large number of functional groups causes curing shrinkage and deteriorates moldability.

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 inferior.

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, they are self-supporting without using a thermoplastic resin or a cross-linking agent. It was possible to form a sufficiently sufficient sheet, and the formability was excellent. At the same time, the dielectric loss tangent was lower than that of the PPE-based thermosetting resin of Comparative Example 4, and the dielectric properties were excellent.

Although some 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 embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments, omissions, replacements, changes, etc. thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

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 corresponds to the divinyl aromatic compound. A thermosetting resin having a repeating unit content of 5 to 20 mol%. The thermosetting resin according to claim 1, which is a linear vinyl copolymer. The thermosetting resin according to claim 1 or 2, which is obtained by reacting a copolymer obtained by copolymerizing vinylbenzylphosphonium halide with a monovinyl aromatic compound with formaldehyde. A cured product obtained 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. The thermosetting composition according to claim 5, which is a printed circuit board material.