JP2018188590A - Thermosetting resin composition and thermosetting resin cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting resin composition and a thermosetting resin cured product having a low relative permittivity and a high light transmittance. At least one selected from the group consisting of cresol novolac type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, trisphenol methane type epoxy resin, dicyclopentadiene type epoxy resin and alicyclic epoxy resin. A thermocurable resin composition containing the epoxy resin (A), a curing agent (B) obtained by polymerizing p-cresol and dicyclopentadiene, and a curing catalyst (C), and the thermocurable resin. A heat-curable resin cured product obtained by heat-curing the composition. [Selection diagram] None

Description

  The present invention relates to a thermosetting resin composition and a thermosetting resin cured product.

  Because printed wiring boards and semiconductor encapsulants are excellent in heat resistance, flame retardancy and molding processability, cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl epoxy resin or trisphenolmethane epoxy resin, etc. And a thermosetting resin composition in which a curing agent such as a phenol novolac resin or a cresol novolac resin is blended and a thermosetting resin cured product obtained by heating and curing the composition are used (Patent Document 1).

  For example, Patent Document 2 discloses an epoxy resin (a) obtained by epoxidizing a polycondensate of dicyclopentadiene and phenol or cresol with epihalohydrin, and a room temperature liquid bisphenol having a viscosity of 100 Pa · s or less at 50 ° C. Type epoxy resin (b), a curing agent selected from phenol novolac resin, cresol novolac resin or phenol aralkyl resin, and an inorganic filler, and the weight ratio of the epoxy resin (a) to the epoxy resin (b) Is 0.5 ≦ a / (a + b) <0.98, and an epoxy resin composition for semiconductor encapsulation containing 60 to 95% by weight of the inorganic filler is described.

  Further, for example, in Patent Document 3, (A) an epoxy resin containing 30 to 100% by weight of a novolac type epoxy resin obtained by co-condensation of paracresol and α-naphthol, based on the total amount of epoxy resin, (B) dicyclo An epoxy resin composition for semiconductor encapsulation containing a phenol resin curing agent containing 30 to 100% by weight of a pentadiene-modified phenol resin with respect to the total amount of phenol resin curing agent, (C) an inorganic filler, and (D) a curing accelerator is described. Has been.

JP 2014-129485 A JP 2009-120815 A JP-A-5-166975

  However, as a result of studies by the present inventors, these epoxy resin composition thermosets have a high relative dielectric constant, and therefore, in high frequency signal circuits used in recent electronic devices, signal delay and loss occur. There was an easy problem. Moreover, in order to use these epoxy resin thermosets for LED (Light Emitting Diode, Light Emitting Diode) sealing materials, there is still room for higher transparency (light transmittance).

  Then, this invention makes it a subject to provide the thermosetting resin composition and thermosetting resin hardened | cured material with the low dielectric constant of a thermosetting material and high light transmittance.

As a result of intensive studies to solve the above problems, the present inventor has obtained a thermosetting resin composition containing a specific epoxy resin (A), a specific curing agent (B), and a curing catalyst (C). Knew that the thermoset had a low relative dielectric constant and a high light transmittance, and completed the present invention.
That is, the present invention includes the following [1] to [5].

[1] At least one selected from the group consisting of a cresol novolac epoxy resin, a phenol novolac epoxy resin, a biphenyl epoxy resin, a trisphenolmethane epoxy resin, a dicyclopentadiene epoxy resin, and an alicyclic epoxy resin. Epoxy resin (A),
a curing agent (B) obtained by polymerizing p-cresol and dicyclopentadiene;
A thermosetting resin composition comprising a curing catalyst (C).
[2] The ratio of the epoxy equivalent of the epoxy resin (A) to the hydroxyl equivalent of the curing agent (B) is the epoxy equivalent of the epoxy resin (A): the hydroxyl equivalent of the curing agent (B) = 0.8: The thermosetting resin composition according to the above [1], which is 1.2 to 1.2: 0.8.
[3] In the above [1] or [2], the content of the curing catalyst (C) is 0.01 to 20% by mass of the total mass of the epoxy resin (A) and the curing agent (B). The thermosetting resin composition as described.
[4] The thermosetting resin composition according to any one of [1] to [3], wherein the curing catalyst (C) is triphenylphosphine.
[5] A cured thermosetting resin obtained by heat-curing the thermosetting resin composition according to any one of [1] to [4].

  According to the present invention, it is possible to provide a thermosetting resin composition and a thermosetting resin cured product having a low relative dielectric constant and a high light transmittance of the thermosetting product.

  The thermosetting resin cured product obtained by heating and curing the thermosetting resin composition of the present invention has a low relative dielectric constant and a high transparency, so that it is a printed wiring board, a semiconductor encapsulant, and an LED encapsulant. Useful for material applications.

Below, the thermosetting resin composition and thermosetting resin hardened | cured material of this invention are demonstrated in detail.
In addition, the range represented using "to" in this specification intends the range including the both ends described before and after "to" in the range.

[Thermosetting resin composition]
The thermosetting resin of the present invention is selected from the group consisting of a cresol novolac epoxy resin, a phenol novolac epoxy resin, a biphenyl epoxy resin, a trisphenolmethane epoxy resin, a dicyclopentadiene epoxy resin, and an alicyclic epoxy resin. Is a thermosetting resin composition comprising a curing agent (B) obtained by polymerizing at least one epoxy resin (A), p-cresol and dicyclopentadiene, and a curing catalyst (C). .

<Epoxy resin (A)>
The epoxy resin (A) is selected from the group consisting of a cresol novolac epoxy resin, a phenol novolac epoxy resin, a biphenyl epoxy resin, a trisphenolmethane epoxy resin, a dicyclopentadiene epoxy resin, and an alicyclic epoxy resin. However, since the relative dielectric constant can be further reduced, at least one selected from the group consisting of a cresol novolac epoxy resin, a phenol novolac epoxy resin, and a dicyclopentadiene epoxy resin is preferable. It is a seed.

《Weight average molecular weight》
Although the weight average molecular weight of the said epoxy resin (A) is not specifically limited, Preferably it is 100-10000, More preferably, it exists in the range of 300-5000. When the weight average molecular weight is 100 or more, the heat resistance of the thermosetting resin cured product is further improved. Moreover, when the weight average molecular weight is 10,000 or less, the viscosity of the thermosetting resin composition when heated becomes lower and the moldability is further improved.

  In addition, the weight average molecular weight of the said epoxy resin (A) is measured by GPC (gel permeation chromatography). The GPC measurement conditions and analysis conditions at this time are as follows.

(GPC measurement conditions)
Column: Shodex GPC KF-803 (Showa Denko)
Shodex GPC KF-802.5 (Showa Denko)
Shodex GPC KF-802 (Showa Denko)
Shodex GPC KF-801 (Showa Denko)
-Elution solvent: THF (tetrahydrofuran)
・ Standard material: PS (polystyrene)
・ Detection: UV (ultraviolet) detector (SPD20A, manufactured by Shimadzu Corporation)
RI (differential refractive index) detector (RID10A, manufactured by Shimadzu Corporation)
・ Flow rate: 0.7 mL / min (use of pump (LC20A, manufactured by Shimadzu Corporation))
Column temperature: 45 ° C. (use of column oven (CTO20A, manufactured by Shimadzu Corporation))

(Analysis conditions)
The weight average molecular weight of the epoxy resin (A) is analyzed using analysis software (LCsolution GPC, manufactured by Shimadzu Corporation). The waveform processing conditions are as follows: width = 30 sec, slope = 40 μV / min, Drift = 0 μV / min, TDBL 1000 min, and minimum area = 1000 counts. Moreover, a low molecular weight component cuts about the peak after 55 minutes.

<< Method for Producing Epoxy Resin (A) >>
The manufacturing method of the said epoxy resin (A) is not specifically limited, A conventionally well-known manufacturing method can be used.
For example, the cresol novolac type epoxy resin is selected from cresols (refers to at least one compound selected from o-cresol, m-cresol, p-cresol, and the same hereinafter) and formaldehyde (formaldehyde and formalin). At least one compound, the same shall apply hereinafter) is synthesized by condensation polymerization in the presence of an acid catalyst to synthesize a phenol resin, and the synthesized phenol resin is further synthesized using an epoxidizing agent such as epichlorohydrin. It can be produced by epoxidation.
In addition, for example, a phenol novolac type epoxy resin is synthesized by subjecting phenol and formaldehyde to condensation polymerization in the presence of an acid catalyst to synthesize a phenol resin, and further, the synthesized phenol resin is added with an epoxidizing agent such as epichlorohydrin. And can be produced by epoxidation.

  The temperature (reaction temperature) at the time of synthesizing a phenol resin by reacting cresols or phenol with formaldehyde is not particularly limited, but is preferably in the range of 30 ° C to 250 ° C, more preferably 50 ° C to It is in the range of 200 ° C, more preferably in the range of 70 ° C to 170 ° C. When the reaction temperature is 30 ° C. or higher, the progress of the reaction becomes faster. Further, when the reaction temperature is 250 ° C. or lower, the acid value of cresols or phenol is sufficiently suppressed, and the color tone of the epoxy resin (A) does not deteriorate.

  The time (reaction time) for synthesizing the phenol resin by reacting cresols or phenol with formaldehyde is not particularly limited, but is preferably in the range of 30 minutes to 20 hours, more preferably 2 hours to Within 12 hours. When the reaction time is 30 minutes or more, the raw material formaldehydes hardly remain. In addition, when the reaction temperature is 20 hours or less, the synthesized phenol resin hardly undergoes thermal decomposition.

The molar ratio of cresols or phenols to formaldehydes in the synthesis of the phenol resin [cresols or moles of phenol / moles of formaldehydes] is not particularly limited, but is preferably 1.0 or more (cresols or Phenol is an excess amount with respect to formaldehydes, more preferably in the range of 1.2 to 100, and still more preferably in the range of 1.5 to 30.
When the molar ratio is 1.2 or more, the synthesized phenol resin has a lower molecular weight, so that the productivity and moldability of the thermosetting resin cured product are further improved. Moreover, since the excess cresol or phenol will reduce that the said molar ratio is 100 or less, productivity of the phenol resin synthesize | combined improves more.

  The acid catalyst for synthesizing the phenol resin is not particularly limited. For example, proton acid such as sulfuric acid, hydrochloric acid, oxalic acid or p-toluenesulfonic acid, or boron trifluoride ether complex or boron trifluoride phenol complex. Lewis acids such as can be used.

  Although the acid catalyst may be removed after the synthesis of the phenol resin, it is not essential because the acid catalyst can be neutralized by adding an alkali metal hydroxide or the like when epoxidizing the synthesized phenol resin. . When the acid catalyst is removed after the synthesis of the phenol resin and before the epoxidation, a method of removing the acid catalyst for the curing agent (B) described later can be applied.

A method for synthesizing an epoxy resin by reacting a phenol resin with an epoxidizing agent such as epichlorohydrin is not particularly limited, and can be performed, for example, as follows.
A phenol resin is dissolved in an excess amount of epichlorohydrin, and an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added, preferably in the range of 50 ° C to 170 ° C, more preferably 60 ° C to The reaction is carried out at a temperature in the range of 140 ° C. for 1 to 10 hours.

  The amount of the epichlorohydrin used is not particularly limited as long as it is excessive with respect to the amount of hydroxyl group of the phenol resin, but preferably 1.5 to 15.0 mol with respect to 1 mol of hydroxyl group of the phenol resin. Yes, more preferably from 2.0 to 7.0 moles.

  The addition amount of the alkali metal oxide is not particularly limited, but is preferably 0.8 to 1.2 mol, more preferably 0.9 to 1.1 mol, with respect to 1 mol of the hydroxyl group of the phenol resin. It is.

  After the epoxidation is completed, unreacted epichlorohydrin is recovered by distillation, and then an organic solvent is added to dissolve the generated epoxy resin. After removing insolubles by filtration, the filtrate is washed with water several times. The remaining inorganic salt is removed, or the solution is washed with water without filtration to remove the remaining inorganic salt, and the organic solvent is distilled off to obtain the epoxy resin (A).

  The organic solvent is not particularly limited as long as it can dissolve the epoxy resin, but is preferably an aromatic compound such as benzene, toluene or xylene, or a ketone organic solvent such as methyl ethyl ketone or methyl isobutyl ketone. Methyl ethyl ketone or methyl isobutyl ketone is more preferred because of its high extraction efficiency and low solubility in water.

It is desirable that the cresols or the excess phenol added as the phenol resin raw material is recovered after the synthesis of the phenol resin and reused as the phenol resin raw material.
The method for recovering the excess of cresols or phenol is not particularly limited, and examples thereof include one method selected from atmospheric distillation, vacuum distillation and steam distillation, or a combination of two or more methods. .

  Although the temperature (distillation temperature) at the time of collect | recovering cresols or phenol by distillation is not specifically limited, Preferably it exists in the range of 100 to 250 degreeC, More preferably, it exists in the range of 140 to 230 degreeC. When the distillation temperature is 100 ° C. or higher, cresols or phenols hardly remain. Further, when the distillation temperature is 250 ° C. or lower, the synthesized phenol resin is hardly thermally decomposed.

  As a method for recovering cresols or phenols, first, atmospheric distillation is performed at a temperature in the range of 140 ° C. to 200 ° C., and further, steam distillation is performed at a temperature in the range of 200 ° C. to 230 ° C. under reduced pressure. The method is particularly preferred. By performing distillation in this way, an epoxy resin (A) with little residual cresols or phenol can be obtained.

<Curing agent (B)>
The curing agent (B) is obtained by polymerizing p-cresol and dicyclopentadiene.

In the present invention, dicyclopentadiene means dicyclopentadiene or a compound in which a hydrogen atom of dicyclopentadiene is substituted with an alkyl group (sometimes referred to as “alkyl-substituted dicyclopentadiene”).
In the above alkyl-substituted dicyclopentadiene, the alkyl group for the hydrogen atom is not particularly limited, but is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group or an ethyl group, still more preferably a methyl group. is there.
In the alkyl-substituted dicyclopentadiene, the number of alkyl groups substituting for hydrogen atoms is not particularly limited as long as it is 12 or less, but is preferably 2 or less, more preferably 1.
Furthermore, in the above alkyl-substituted dicyclopentadiene, when there are a plurality of alkyl groups replacing hydrogen atoms, the alkyl groups may be different types of alkyl groups, or may be the same type of alkyl groups. Good.

A curing agent (B) is obtained by polymerizing p-cresol and dicyclopentadiene.
Moreover, in the said Formula (2) and said Formula (3), m will not be specifically limited if it is an integer of 0-12, Preferably it is an integer of 0-3, More preferably, it is 0.

  The said hardening | curing agent (B) may contain an unavoidable mixture other than the polymer of p-cresol and dicyclopentadiene. Here, inevitable contaminants are, for example, unreacted raw materials (p-cresol and dicyclopentadiene), reaction intermediates, residual acid catalyst, organic solvent used in purification, water, and the like.

<< Method for Producing Curing Agent (B) >>
The curing agent (B) can be produced by polymerizing p-cresol and dicyclopentadiene (dicyclopentadiene and its alkyl-substituted product, the same shall apply hereinafter) in the presence of an acid catalyst.

  The mixing method of p-cresol and dicyclopentadiene when polymerizing p-cresol and dicyclopentadiene is not particularly limited, but preferably by dropping dicyclopentadiene into p-cresol dissolved by heating. Do. Although the temperature which heats p-cresol in this case is not specifically limited, Preferably it is below the reaction temperature mentioned later.

The temperature (reaction temperature) for polymerizing p-cresol and dicyclopentadiene is not particularly limited, but is preferably in the range of 50 ° C to 200 ° C, more preferably in the range of 60 ° C to 170 ° C. More preferably, it is in the range of 70 ° C to 150 ° C.
When the reaction temperature is 50 ° C. or higher, the progress rate of the polymerization reaction becomes faster and the reaction time can be shortened. Further, when the reaction temperature is 200 ° C. or lower, the oxidation of p-cresol is sufficiently suppressed, and the color tone of the curing agent (B) does not deteriorate.

The time (reaction time) for polymerizing p-cresol and dicyclopentadiene is not particularly limited, but is preferably in the range of 30 minutes to 20 hours, more preferably in the range of 1 hour to 20 hours. More preferably, it is in the range of 2 hours to 12 hours.
When the reaction time is 30 minutes or longer, the raw material dicyclopentadiene hardly remains. Further, when the reaction temperature is 20 hours or less, the synthesized polymer is hardly thermally decomposed.

The molar ratio of p-cresol and dicyclopentadiene in the polymerization of p-cresol and dicyclopentadiene [number of moles of p-cresol / number of moles of dicyclopentadiene] is not particularly limited, but preferably 1.0 or more (p-cresol is excessive with respect to dicyclopentadiene), more preferably in the range of 1.2 to 100, and still more preferably in the range of 1.5 to 30.
When the above molar ratio is 1.2 or more, the molecular weight of the polymer of p-cresol and dicyclopentadiene becomes lower, so that the productivity and moldability of the cured thermosetting resin are more excellent It becomes. Moreover, since the excess p-cresol reduces that the said molar ratio is 100 or less, the productivity of the polymer synthesize | combined improves more.

The acid catalyst for polymerizing p-cresol and dicyclopentadiene is not particularly limited. For example, proton acid such as sulfuric acid, hydrochloric acid, oxalic acid or p-toluenesulfonic acid, or boron trifluoride ether complex or Lewis acids such as boron trifluoride phenol complex can be used.
The acid catalyst is preferably removed by neutralizing the catalyst after a predetermined reaction time and filtering or extracting. If the acid catalyst remains, when the thermosetting resin cured product of the present invention is used as a material for a printed wiring board, a semiconductor encapsulant, or an LED encapsulant, the insulation becomes worse and the circuit is corroded. .
As a method for removing the acid catalyst, after a predetermined reaction time has elapsed, after completion of the synthesis of the polymer of p-cresol and dicyclopentadiene, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate or the like is added to the reaction mixture. To neutralize the acid catalyst by adding an alkaline substance, to adsorb the acid catalyst by adding an adsorbent such as hydrotalcite to the reaction mixture, and then filter and remove the adsorbent together, the reaction mixture Or a method of using these in combination.

It is desirable that the excess p-cresol added as a raw material for the curing agent (B) is recovered after synthesis and reused as a raw material for the curing agent (B).
Although the method of collect | recovering the excess of p-cresol is not specifically limited, For example, the method of 1 type selected from atmospheric distillation, vacuum distillation, and steam distillation, or the combination of 2 or more types can be mentioned.

  Although the temperature (distillation temperature) at the time of collect | recovering p-cresol by distillation is not specifically limited, Preferably it exists in the range of 100 to 250 degreeC, More preferably, it exists in the range of 140 to 230 degreeC. When the distillation temperature is 100 ° C. or higher, p-cresol hardly remains. Further, when the distillation temperature is 260 ° C. or lower, the synthesized polymer is unlikely to be thermally decomposed.

  As a method for recovering p-cresol, first, atmospheric distillation is performed at a temperature within a range of 140 ° C. to 200 ° C., and further, steam distillation is performed at a temperature within a range of 200 ° C. to 230 ° C. under reduced pressure. Is particularly preferred. By performing distillation in this way, a curing agent (B) with little remaining p-cresol can be obtained.

<Mixing ratio of epoxy resin (A) and curing agent (B)>
The mixing ratio of the epoxy resin (A) and the curing agent (B) when producing the thermosetting resin composition of the present invention is not particularly limited, but the epoxy equivalent of the epoxy resin (A) and the curing agent are not limited. The ratio of the hydroxyl equivalent of (B) [epoxy equivalent of epoxy resin (A): hydroxyl equivalent of curing agent (B)] is preferably 0.8: 1.2 to 1.2: 0.8, and more Preferably it is 0.9: 1.1-1.1: 0.9, More preferably, it is 0.95: 1.05-1.05: 0.95.

<Curing catalyst (C)>
The curing catalyst (C) is not particularly limited, and conventionally known curing catalysts for epoxy resins can be used, but preferably triphenylphosphine; tertiary amines such as benzyldimethylamine and dimethylaminomethylphenol; Imidazoles such as 2-ethyl-4-methylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole; modified products of these imidazoles with acrylonitrile, trimellitic acid or dicyandiamide; quaternary ammonium salts: quaternary A phosphonium compound, more preferably triphenylphosphine.
Among the above curing catalysts, modified products of tertiary amines, imidazoles and imidazoles not only act as curing catalysts (curing accelerators) but also act as curing agents themselves and form a crosslinked structure with the epoxy resin. There is a problem that the glass transition temperature (Tg) of the obtained thermosetting resin cured product is lowered or the relative dielectric constant is increased.
Of the above curing catalysts, quaternary ammonium salts and quaternary phosphonium compounds contain halogen or the like as a counter ion. Therefore, when the obtained thermosetting resin cured product is used for an electronic substrate, the dielectric constant is There is a problem that the rate is high and the circuit is easily corroded.
Therefore, when tertiary amines, imidazoles, modified products of imidazoles, quaternary ammonium salts or quaternary phosphoniums are used as curing catalysts, it is desirable to use them only for applications that allow the above problems.

  Although the usage-amount of a curing catalyst (C) is not specifically limited, Preferably it is 0.01-20 mass% of the total mass of an epoxy resin (A) and a hardening | curing agent (B), More preferably, it is 0.1-0.1%. It is 10 mass%, More preferably, it is 0.2-5.0 mass%.

<Other components (D)>
In addition to the epoxy resin (A), the curing agent (B) and the curing catalyst (C), the thermosetting resin composition of the present invention contains other components within a range where the object of the present invention can be achieved. May be included.
Examples of the other components include fibers such as glass fibers or carbon fibers; inorganic materials such as silica, alumina, zirconia, or boron nitride; and additives such as a lubricant such as carbon black or zinc stearate. .

[Thermosetting resin cured product]
The thermosetting resin cured product of the present invention is obtained by heat-curing the thermosetting resin composition of the present invention.
The thermosetting resin composition of the present invention has a low relative dielectric constant and a high light transmittance.
The relative dielectric constant is usually 2.80 or less, preferably 2.70 or less, and more preferably 2.60 or less. The lower the dielectric constant, the lower the loss at high frequencies and the better high frequency characteristics.
The light transmittance is usually 50% or more, preferably 55% or more, and more preferably 60% or more as a result of measurement using a light source having a wavelength of 450 nm and a thickness of 3.0 mm.

  Further, the cured thermosetting resin of the present invention has a small dielectric loss tangent and excellent high frequency characteristics. The dielectric loss tangent of the cured thermosetting resin of the present invention is not particularly limited, but is preferably 0.020 or less, more preferably 0.018 or less, and further preferably 0.015 or less.

  Furthermore, the thermosetting resin cured product of the present invention has a high glass transition temperature and excellent heat resistance. Although the glass transition temperature of the thermosetting resin cured product of the present invention is not particularly limited, it is preferably 140 ° C. or higher, more preferably 150 ° C. or higher, and further preferably 155 ° C. or higher.

In the present invention, the relative permittivity, dielectric loss tangent, light transmittance and glass transition temperature are measured by the following methods.
(Relative permittivity / dielectric loss tangent)
A dielectric constant (ε) and a dielectric loss tangent (tan δ) are measured by a coaxial resonator method using a dielectric constant measuring apparatus (manufactured by AET Co., Ltd.) under a resonance frequency condition of 1 GHz. The relative permittivity (ε _r ) is obtained by dividing the permittivity (ε) by the value of the vacuum permittivity (ε ₀ ).
(Light transmittance)
The light transmittance (%) of the measurement sample at a wavelength of 50 nm is measured using a UV spectrum measurement device (UV-1650PC, manufactured by Shimadzu Corporation).
(Glass-transition temperature)
Using a linear expansion coefficient measuring device (TMA-50, manufactured by Shimadzu Corporation), the temperature was increased at 10 ° C./min, the expansion coefficient was measured by a penetration method, and the temperature at the inflection point was determined as the glass transition temperature ( Tg).

<< Method for producing thermosetting resin cured product >>
The method for heat-curing the thermosetting resin composition of the present invention is not particularly limited, and a conventionally known method for heat-curing an epoxy resin composition can be applied.
The temperature of heating and curing (heating temperature) is not particularly limited, but is preferably in the range of 50 ° C to 300 ° C, more preferably in the range of 100 ° C to 250 ° C, and further preferably 120 ° C to 220 ° C. Is within the range.
The time for heating and curing (heating time) is not particularly limited, but is preferably in the range of 30 minutes to 20 hours, more preferably in the range of 3 hours to 10 hours.
Moreover, you may carry out on pressurization conditions, when shape | molding the thermosetting resin cured | curing material of this invention.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

[Manufacture of epoxy resin]
1. Epoxy resin A1
(1) Synthesis of cresol novolac resin In a 1 L reaction vessel (separable flask) equipped with a stirrer, a thermometer, a reflux device, an inert gas introduction tube and an oil bath, 250 g of o-cresol and 50 g of paraformaldehyde Formalin 57.5 g was added, and the oil bath was heated to 105 ° C. to obtain a reaction mixture. Next, an aqueous catalyst solution prepared by dissolving 0.5 g of p-toluenesulfonic acid (acid catalyst) in 5.0 g of ion-exchanged water was dropped into the obtained mixture over 10 minutes. After the dropwise addition, the reaction was carried out for 6.0 hours while maintaining the temperature of the oil bath at 105 ° C., and then a 10% aqueous solution of potassium hydroxide was added to neutralize the acid catalyst. After neutralization of the acid catalyst, the oil bath was heated to 220 ° C., and unreacted o-cresol was removed by distillation under reduced pressure. After the distillation of o-cresol stopped, o-cresol was removed under reduced pressure for another 30 minutes. Then, it cooled to room temperature and obtained 260 g of cresol novolak resins.
The weight average molecular weight measured by gel permeation chromatography (GPC) of the obtained cresol novolac resin was 4250.

  The GPC measurement conditions and analysis conditions were as follows.

(Measurement condition)
Column: Shodex GPC KF-803 (target molecular weight range 1000 to 50000; exclusion limit molecular weight 70000; manufactured by Showa Denko KK)
Shodex GPC KF-802.5 (Showa Denko)
Shodex GPC KF-802 (Showa Denko)
Shodex GPC KF-801 (Showa Denko)
-Elution solvent: THF (tetrahydrofuran)
・ Standard material: PS (polystyrene)
・ Detection: UV (ultraviolet) detector (SPD20A, manufactured by Shimadzu Corporation)
RI (differential refractive index) detector (RID10A, manufactured by Shimadzu Corporation)
・ Flow rate: 0.7 mL / min (use of pump (LC20A, manufactured by Shimadzu Corporation))
Column temperature: 45 ° C. (use of column oven (CTO20A, manufactured by Shimadzu Corporation))
An auto sampler (SIL20A, manufactured by Shimadzu Corporation) was used for sampling the measurement sample.

(Analysis conditions)
The weight average molecular weight of the epoxy resin (A) was analyzed using analysis software (LCsolution GPC, manufactured by Shimadzu Corporation). The waveform processing conditions were as follows: width = 30 sec, slope = 40 μV / min, Drift = 0 μV / min, TDBL 1000 min, and minimum area = 1000 counts. Further, the low molecular weight component was cut for peaks after 55 minutes.

(2) Epoxidation of cresol novolac resin Next, 50 g of the obtained cresol novolak resin was added to a 500 mL four-necked flask equipped with a stirrer, a thermometer, a reflux device, an inert gas introduction tube and an oil bath, 102.8 g of chlorohydrin (chloromethyloxirane) was added, and 30.6 g of dimethyl sulfoxide was further added as a solvent, and the internal temperature was adjusted to 40 ° C. To this mixture, 11.2 g of sodium hydroxide (flake) was added in 10 portions and divided every 6 minutes. After completion of the addition, the reaction was carried out at 50 ° C. for 1 hour and at 70 ° C. for 1 hour, and then the temperature was raised to 130 ° C. and vacuum distillation was carried out to remove excess epichlorohydrin. After the distillation under reduced pressure, 230 g of methyl ethyl ketone was added, copied to a separatory funnel, and washed with 200 mL of ion exchange water. This washing operation was repeated until the aqueous phase became neutral. Thereafter, the organic phase was put into a 500 mL eggplant flask and methyl ethyl ketone was removed with an evaporator to obtain 84 g of a cresol novolac type epoxy resin.
The obtained cresol novolac type epoxy resin is referred to as “epoxy resin A1”.
The weight average molecular weight obtained by measurement and analysis by GPC of the epoxy resin A1 was 870. The GPC measurement conditions and analysis conditions are as described above.

  When the epoxy equivalent of the epoxy resin A1 was measured by the method of JIS K 7263: 2001 “How to determine the epoxy equivalent of an epoxy resin”, the epoxy equivalent was 205 g / equivalent.

2. Epoxy resin A2
(1) Synthesis of trisphenol methane type phenol resin Trisphenol methane type phenol resin was synthesized by reacting lithylaldehyde with phenol.
(2) Epoxidation of trisphenol methane type phenol resin In the same manner as the epoxidation of the cresol novolac resin, the obtained trisphenol methane type phenol resin was epoxidized to obtain a trisphenol methane type epoxy resin (epoxy equivalent = 165 g / Equivalent).
Let the obtained trisphenol methane type epoxy resin be "epoxy resin A2."
The weight average molecular weight obtained by GPC measurement and analysis of the epoxy resin A2 was 730. The GPC measurement conditions and analysis conditions are as described above.

3. Epoxy resin A3
(1) Synthesis of Phenol / Dicyclopentadiene Condensate Phenol and dicyclopentadiene were reacted to synthesize a phenol / dicyclopentadiene condensate.
(2) Epoxidation of phenol / dicyclopentadiene condensate In the same manner as the epoxidation of the cresol novolac resin, the obtained phenol / dicyclopentadiene condensate is epoxidized to epoxidize the phenol / dicyclopentadiene condensate. (Epoxy equivalent = 260 g / equivalent) was obtained.
The epoxidized product of the obtained phenol-dicyclopentadiene condensate is referred to as “epoxy resin A3”.
The weight average molecular weight obtained by measurement and analysis by GPC of the epoxy resin A3 was 1050. The GPC measurement conditions and analysis conditions are as described above.

4). Epoxy resin A4
(1) Synthesis of phenol novolac resin Phenol was reacted with p-formaldehyde and formalin in the same manner as in the above cresol novolac resin synthesis to obtain a phenol novolac resin.
(2) Epoxidation of phenol novolak resin In the same manner as the epoxidation of the cresol novolak resin, the obtained phenol novolak resin was epoxidized to obtain a phenol novolak type epoxy resin (epoxy equivalent = 195 g / equivalent).
The obtained phenol novolac type epoxy resin is referred to as “epoxy resin A4”.
The weight average molecular weight obtained by measuring and analyzing by GPC of the epoxy resin A4 was 950. The GPC measurement conditions and analysis conditions are as described above.

[Manufacture of curing agent]
1. Curing agent B1
66 g of p-cresol was placed in a 1 L reaction vessel (separable flask) equipped with a stirrer, thermometer, reflux device, dropping funnel, inert gas introduction tube and oil bath, and the oil bath temperature was raised to 105 ° C. Thereafter, 4.0 g of boron trifluoride phenol complex as a catalyst was added. Furthermore, 88 g of dicyclopentadiene was added over 1 hour, and then the temperature was raised to 120 ° C. and reacted for 5 hours. After the reaction, hydrotalcite was added as a neutralizing agent and stirred for 20 minutes, and then the hydrotalcite was removed by filtration. The filtrate was again put in a 1 L reaction vessel, and subjected to atmospheric distillation and vacuum distillation to remove excess p-cresol, to obtain a p-cresol dicyclopentadiene condensate.
The obtained p-cresol / dicyclopentadiene condensate is referred to as “curing agent B1”.

  When the hydroxyl equivalent of the curing agent B1 was measured according to JIS K 0070: 1992 “Testing method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products”, the hydroxyl equivalent was 184 g. / Equivalent.

2. Curing agent b2
An m-cresol dicyclopentadiene condensate (hydroxyl equivalent = 184 g / equivalent) was synthesized in the same manner as the curing agent B1, except that m-cresol was used instead of p-cresol.
This m-cresol dicyclopentadiene condensate is referred to as “curing agent b2.”

3. Curing agent b3
An o-cresol dicyclopentadiene condensate (hydroxyl equivalent = 184 g / equivalent) was synthesized in the same manner as the curing agent B1, except that o-cresol was used instead of p-cresol.
This o-cresol dicyclopentadiene condensate is referred to as “curing agent b3”.

4). Curing agent b4
A phenol-dicyclopentadiene condensate (hydroxyl equivalent = 170 g / equivalent) was synthesized in the same manner as the curing agent B1, except that phenol was used instead of p-cresol.
This phenol-dicyclopentadiene condensate is referred to as “curing agent b4”.

5. Curing agent b5
A phenol-formaldehyde condensate (hydroxyl equivalent = 105 g / equivalent) was synthesized from phenol and formaldehyde.
This phenol-formaldehyde condensate is referred to as “curing agent b5”.

[Test / Evaluation Method]
1. Dielectric properties (dielectric constant and dielectric loss tangent)
(1) Preparation of measurement sample A thermosetting resin cured product (thickness: about 3.0 mm) was cut into a 40 mm x 40 mm square, and the surface was polished and smoothed with sandpaper to obtain a measurement sample.
(2) Measurement of relative permittivity (ε _r ) and dielectric loss tangent (tan δ) The sample for measurement was polished on an open coaxial resonator (manufactured by AET), and the smoothed surface faced down. Then, the dielectric constant (ε) and the dielectric loss tangent (tan δ) were measured by a coaxial resonator method using a dielectric constant measuring apparatus (manufactured by AET Co., Ltd.) under the condition of a resonance frequency of 1 GHz. The relative permittivity (ε _r ) was obtained by dividing the permittivity (ε) by the value of the vacuum permittivity (ε ₀ ).
If the relative dielectric constant (ε _r ) is 2.80 or less, it can be evaluated that the signal propagation delay time at high frequencies is small and the high frequency characteristics are excellent.
If the dielectric loss tangent (tan δ) is 0.020 or less, it can be evaluated that the loss at high frequency is small and the high frequency characteristics are excellent.

2. Light Transmittance Using a thermosetting resin cured product (thickness: 3.0 mm) as a measurement sample, using a UV spectrum measuring device (UV-1650PC, manufactured by Shimadzu Corporation), the light transmittance of the measurement sample at a wavelength of 450 nm ( %).
If the light transmittance is 50% or more, it can be evaluated that the transparency is excellent.

3. Glass transition temperature (Tg)
(1) Preparation of measurement sample A thermosetting resin cured product (thickness: about 5.0 mm) was cut into a 5 mm square cube to obtain a measurement sample.
(2) Measurement of glass transition temperature (Tg) Using a linear expansion coefficient measuring device (TMA-50, manufactured by Shimadzu Corporation), the measurement sample was heated at 10 ° C./min, and the expansion coefficient was measured by the penetration method. The temperature at the inflection point was taken as the glass transition temperature (Tg) of the measurement sample.
If the glass transition temperature (Tg) is 150 ° C. or higher, it can be evaluated that the heat resistance is excellent.

[Example 1]
1. Production of Epoxy Resin Composition To an aluminum cup, 3 g of epoxy resin A1 and 2.7 g of curing agent B1 were added, heated to 160 ° C. on a hot plate, stirred with a spatula and mixed uniformly. After mixing, the temperature was lowered to 140 ° C., 0.1 g of triphenylphosphine (curing catalyst) was put into an aluminum cup containing the mixture, and stirred again with a spatula and mixed uniformly to obtain an epoxy resin composition. .
This epoxy resin composition is referred to as “epoxy resin composition X1”.

2. Production of cured epoxy resin The epoxy resin composition X1 is cured by heating at 160 ° C. for 2 hours, 180 ° C. for 2 hours, and 190 ° C. for 1 hour to obtain a flat plate having a thickness of about 3.0 mm or a thickness of about 5.0 mm. A cured epoxy resin was obtained.
This cured epoxy resin is referred to as “cured epoxy resin Y1”.
3. Test and evaluation of dielectric properties (dielectric constant, dielectric loss tangent), light transmittance and glass transition temperature In accordance with the above “test / evaluation method”, dielectric properties (dielectric constant, dielectric loss tangent) of cured epoxy resin Y1 The transmittance and glass transition temperature were measured and evaluated.
The measurement results are shown in the corresponding column of Table 1.

[Examples 2 to 4]
As in the case of Example 1, except that the epoxy resin A2 (Example 2), the epoxy resin A3 (Example 3) or the epoxy resin A4 (Example 4) is used as the epoxy resin instead of the epoxy resin A1. Thus, an epoxy resin composition and a cured epoxy resin were produced.
According to the above-mentioned “test / evaluation method”, dielectric properties (dielectric constant, dielectric loss tangent), light transmittance and glass transition temperature of the produced cured epoxy resin were measured and evaluated.
The measurement results are shown in the corresponding column of Table 1.

[Comparative Examples 1-6]
An epoxy resin composition and a cured epoxy resin were produced in the same manner as in Example 1 except that the combination of the epoxy resin and the curing agent was changed as shown in Table 1.
According to the above-mentioned “test / evaluation method”, dielectric properties (dielectric constant, dielectric loss tangent), light transmittance and glass transition temperature of the produced cured epoxy resin were measured and evaluated.
The measurement results are shown in the corresponding column of Table 1.

[Explanation of results]
The cured epoxy resins of Examples 1 to 4 each had a low relative dielectric constant and a high light transmittance.

<Example 1, Comparative Example 1 and Comparative Example 2>
Comparative Example 1 and Comparative Example 2 are examples in which a phenol / dicyclopentadiene condensate (curing agent b4) or a phenol / formaldehyde condensate (curing agent b5) was used as the curing agent, respectively.
In both Comparative Example 1 and Comparative Example 2, the relative dielectric constant was high and the light transmittance was low.
From these results, when a curing agent obtained by polymerizing p-cresol and dicyclopentadiene is used as the curing agent, the resulting thermosetting resin cured product has a low relative dielectric constant and a high light transmittance. You can see that you can.
Further, when a phenol / dicyclopentadiene condensate or a phenol / formaldehyde condensate is used as a curing agent instead of a curing agent obtained by polymerizing p-cresol and dicyclopentadiene, a relative dielectric constant and light transmittance are desired. It can be seen that the above-mentioned levels (relative permittivity ≦ 2.80, light transmittance ≧ 50%) are not satisfied.

<Example 1, Comparative Example 5 and Comparative Example 6>
Example 1 is an example using p-cresol dicyclopentadiene condensate (curing agent B1) as a curing agent. In Comparative Examples 5 and 6, m-cresol / dicyclopentadiene condensate (curing agent b2) or o-cresol / dicyclopentadiene condensate (curing agent b3) was used as the curing agent, respectively. It is.
The relative dielectric constant (epsilon _r) is the comparative example 6 was low (ε _r = 2.50) is, in Comparative Example 5 was high (ε _r = 2.85). The light transmittance was low in both Comparative Example 5 and Comparative Example 6 (<50%).
In contrast, in Example 1, the relative dielectric constant (ε _r ) was low (ε _r = 2.41), and the light transmittance was high (≧ 50%).
From these results, when a curing agent obtained by polymerizing p-cresol and dicyclopentadiene is used as the curing agent, the resulting thermosetting resin cured product has a low relative dielectric constant and a high light transmittance. You can see that you can.
Furthermore, when a curing agent obtained by polymerizing m-cresol or o-cresol and dicyclopentadiene instead of p-cresol is used, it can be seen that the light transmittance does not satisfy a desired level (≧ 50%). .

<Examples 1-4>
Examples 1 to 4 are examples using epoxy resins A1 to A4 as epoxy resins, respectively.
Examples of the epoxy resin include cresol novolac type epoxy resin (epoxy resin A1), trisphenolmethane type epoxy resin (epoxy resin A2), dicyclopentadiene type epoxy resin (epoxy resin A3), and phenol novolac type epoxy resin (epoxy resin A4). It can be seen that any of these can reduce the relative dielectric constant and increase the light transmittance.

Claims (5)

At least one epoxy resin selected from the group consisting of a cresol novolac epoxy resin, a phenol novolac epoxy resin, a biphenyl epoxy resin, a trisphenolmethane epoxy resin, a dicyclopentadiene epoxy resin, and an alicyclic epoxy resin ( A) and
a curing agent (B) obtained by polymerizing p-cresol and dicyclopentadiene;
A thermosetting resin composition comprising a curing catalyst (C).   The ratio of the epoxy equivalent of the epoxy resin (A) to the hydroxyl equivalent of the curing agent (B) is the epoxy equivalent of the epoxy resin (A): the hydroxyl equivalent of the curing agent (B) = 0.8: 1.2. The thermosetting resin composition of Claim 1 which is -1.2: 0.8.   The thermosetting resin according to claim 1 or 2, wherein a content of the curing catalyst (C) is 0.01 to 20% by mass of a total mass of the epoxy resin (A) and the curing agent (B). Composition.   The thermosetting resin composition according to any one of claims 1 to 3, wherein the curing catalyst (C) is triphenylphosphine.   The thermosetting resin hardened | cured material which heat-hardened the thermosetting resin composition of any one of Claims 1-4.