Novel thermally conductive compounds

Abstract

To provide novel compounds with high thermal conductivity.SOLUTION: A compound is represented by the formula (EP1). In the formula, n represents the number of repeats of the structure in the parentheses and is an integer of 1 or more; the multiple R1 are identical to each other, the multiple R2 are identical to each other, the multiple R3 are identical to each other, the multiple R4 are identical to each other, the multiple R5 are identical to each other, the multiple R6 are identical to each other identical to each other, the multiple R7 are identical to each other, and the multiple R8 are identical to each other, and R1, R2, R3, R4, R5, R6, R7 and R8 are each independently a hydrogen atom or a C1-3 alkyl group; X is a C2-6 alkylene group; Y is a group represented by the formula (ep) in the figure; and r is an integer from 1 to 3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a compound having high thermal conductivity. [Background technology]

[0002] With the rapid increase in semiconductor integration and processing power of electronic devices, high-performance electronic components generate a significant amount of heat. Therefore, effective heat dissipation measures to remove heat from these components have become a crucial issue. To address this, heat-conducting materials such as metals, ceramics, and polymer compositions are used in heat dissipation components like printed circuit boards, semiconductor packages, enclosures, heat pipes, heat sinks, and heat diffusers.

[0003] Among these heat dissipation components, thermally conductive epoxy resin molded products, which are formed from epoxy resin compositions, are widely used, mainly in the electrical and electronic fields, as cast products, laminates, encapsulants, thermally conductive sheets, adhesives, etc., due to their excellent electrical insulation, mechanical properties, heat resistance, chemical resistance, and adhesive properties.

[0004] Epoxy resin compositions that constitute thermally conductive epoxy resin molded articles are known to be those in which a highly thermally conductive filler with high thermal conductivity is blended into a polymer matrix material such as resin or rubber. However, when even higher thermal conductivity is required, it has also been proposed to improve the thermal conductivity and heat resistance of the epoxy resin itself (for example, Patent Document 1). Patent Document 1 describes obtaining an insulating composition with improved thermal conductivity by polymerizing a liquid crystalline epoxy resin having mesogenic groups. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent Application No. 2004-331811 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, as a result of the study by the present inventors, it has been found that the resin composition described in Patent Document 1 has room for further improvement in thermal conductivity.

Means for Solving the Problems

[0007] The present invention has been made in view of the above problems, and has completed the present invention by finding that a novel epoxy resin having a specific structure has high thermal conductivity.

[0008] According to the present invention, the following compounds are provided. [1] A compound represented by formula (EP1),

Chemical formula

Chemical formula

Chemical formula

[10] A compound according to any of items [6] to [9], wherein n in formula (PH1) is 1. [Effects of the Invention]

[0009] According to the present invention, an epoxy compound having high thermal conductivity and high liquid crystallinity, and a precursor compound thereof are provided.

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described. In this specification, the description "~" represents "from above to below" unless otherwise specified.

[0011] [First Embodiment] The compound in the first embodiment is an epoxy compound having an epoxy group and has a structure represented by the formula (EP1).

[0012]

Chemical Formula

[0013] In the formula (EP1), n represents the number of repetitions of the structure in parentheses and is an integer of 1 or more. n is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 10. A plurality of R 1 with each other, R 2 with each other, R 3 with each other, R 4 with each other, R 5 with each other, R 6 with each other, R 7 with each other, and R 8 with each other are identical to each other, and R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 are independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an iso-propyl group. X is an alkylene group having 2 to 6 carbon atoms (-(CH2) p-, p=2~6). Examples of alkylene groups having 2 to 6 carbon atoms include ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, etc. Preferably, n-propylene, n-butylene, and n-pentylene, more preferably n-butylene and n-pentylene, and even more preferably n-pentylene. Y is a base represented by equation (ep).

[0014] [ka]

[0015] In formula (ep), r is an integer between 1 and 3. r is preferably 1 or 2, and more preferably 1.

[0016] In one embodiment, the compound represented by formula (EP1) is a single compound where n is the number of repeating units in parentheses. When it is a single compound, n in formula (EP1) is, for example, an integer from 1 to 10, preferably an integer from 1 to 5, more preferably 1 or 2, and even more preferably 1.

[0017] In one embodiment, the compound represented by formula (EP1) is a mixture of various compounds with different numbers of repeating units n in parentheses. When it is a mixture, the average value of n in formula (EP1) is, for example, 1 to 10, preferably 1 to 9, and more preferably 1 to 8.

[0018] In one embodiment, the epoxy compound of the present invention is R in formula (EP1). 1 , R 2 , R 3 , and R 4 At least one of them is an alkyl group having 1 to 3 carbon atoms, and the rest are hydrogen atoms, and R in formula (EP1) 5 , R 6 , R 7 , and R 8 It has a structure in which at least one of the atoms is an alkyl group with 1 to 3 carbon atoms, and the rest are hydrogen atoms.

[0019] In one embodiment, the epoxy compound of the present invention is R in formula (EP1). 1 , R 2 , R 3 , and R 4 One of them is an alkyl group with 1 to 3 carbon atoms, and the remaining three are hydrogen atoms, and R in formula (EP1) 5 , R 6 , R 7 , and R 8 It has a structure in which one of the elements is an alkyl group and the remaining three are hydrogen atoms.

[0020] In a preferred embodiment, the epoxy compound of the present invention is R in formula (EP1). 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 It has a structure in which all of its atoms are hydrogen atoms.

[0021] The method for producing the epoxy compound in this embodiment is not particularly limited, and depending on the target epoxy compound, the starting material can be selected and known reaction steps / methods can be used. For example, the epoxy compound of this embodiment can be synthesized by starting with a biphenyl compound represented by formula (BP) and sequentially following the steps (1) and (2) below. The reaction scheme for steps (1) to (2) is shown below. (Step 1) A step in which a polyhydric phenol compound represented by formula (BP) is reacted with a compound represented by formula (2) to obtain a compound represented by formula (PH1). (Step 2) A step in which the compound of formula (PH1) obtained in (Step 1) above is reacted with an epihalohydrin represented by formula (3) to obtain the compound represented by formula (EP1) of this embodiment.

[0022] [ka]

[0023] R in equation (BP) 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 This is equivalent to the one in formula (EP11) above. In equation (2), q is an integer between 0 and 4, and X 2 It is a halogen atom. In formula (PH1), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 , and X are equivalent to those in the above formula (EP1). In equation (3), q is an integer between 0 and 2, and X 3 It is a halogen atom.

[0024] In step 1 described above, the compound of formula (PH1) can be produced by reacting a polyhydric phenol compound represented by formula (BP) with the compound represented by formula (2) in a solvent in the presence of a base. Examples of compounds represented by formula (2) include, but are not limited to, 1,2-dibromoethane, 1,3-dibromopropane, 1,3-dichloropropane, 1,4-dichlorobutane, 1,4-dibromobutane, and 1,5-dibromopentane.

[0025] Examples of bases used in the reaction described above (Step 1) include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal bicarbonates such as sodium bicarbonate; alkali metal alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, and potassium tert-butoxide; and organic bases such as triethylamine and pyridine. The amount of base used is usually 2 to 5 molar times the amount of the compound shown in formula (2).

[0026] The reaction temperature in the above step (1) is, for example, 10°C to 150°C.

[0027] The organic solvent used in step 1 above can be any solvent that is inert to the reaction. Examples include alcoholic solvents such as methanol, ethanol, propyl alcohol, butanol, ethylene glycol, and propylene glycol; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; aprotic polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; and ether solvents such as tetrahydrofuran, dioxane, methoxymethyl ether, and diethoxyethane. These solvents may be used individually or in combination of two or more. Among these, aprotic polar solvents are preferred. The amount of organic solvent used is not particularly limited.

[0028] In (Step 1), the compound of formula (BP), the compound of formula (2), and a base are mixed in a solvent and heated as appropriate to allow the reaction between the compound of formula (BP) and the compound of formula (2) to proceed. After the reaction is complete, for example, after filtering out the insoluble matter from the reaction solution, water and an organic solvent insoluble in water are added and extracted to obtain an organic layer containing the polyhydric phenol compound represented by formula (PH1). The polyhydric phenol compound represented by formula (PH1) can be isolated by concentrating the organic layer. The isolated polyhydric phenol compound represented by formula (PH1) may be purified by conventional purification methods to obtain a mixture of polyhydric phenol compounds within a predetermined molecular weight range, or a polyhydric phenol compound having a predetermined molecular weight may be obtained as a single compound.

[0029] In the subsequent (Step 2), the polyhydric phenol compound represented by formula (PH1) obtained in (Step 1) is glycidylated.

[0030] In the glycidylation reaction of the polyhydric phenol compound in step 2 described above, a solid alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added as a catalyst to a mixture of the polyhydric phenol compound represented by formula (PH1) and the epihalohydrins represented by formula (3), or the mixture is reacted at 20 to 120°C for 0.5 to 10 hours while adding the catalyst. The alkali metal hydroxide may be used as an aqueous solution, in which case the alkali metal hydroxide may be added continuously, and water and epihalohydrins may be continuously distilled from the reaction mixture under reduced pressure or atmospheric pressure, followed by the removal of water by liquid-liquid extraction and the continuous return of only the epihalohydrins to the reaction mixture.

[0031] Examples of epihalohydrins represented by formula (3) used in the glycidylation reaction in (Step 2) include epichlorohydrin, epibromohydrin, and epiiodohydrin, with epichlorohydrin being preferred. The preferred amount of epihalohydrins used is 0.5 to 6 moles, more preferably 0.55 to 3 moles, per mole of hydroxyl groups in the polyhydric phenol compound represented by formula (PH1). The amount of alkali metal hydroxide used is usually 0.5 to 2.0 moles, preferably 0.7 to 1.5 moles, per mole of hydroxyl groups in the polyhydric phenol compound represented by formula (PH1).

[0032] The glycidylation reaction in (Step 2) may be carried out in a solvent. The solvent that can be used in the reaction is not particularly limited as long as it can dissolve the polyhydric phenol compound represented by formula (PH1) and does not adversely affect the reaction. Examples of solvents that can be used include alcohols such as methanol, ethanol, and propanol, aprotic polar solvents such as dimethyl sulfone, dimethyl sulfoxide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, dioxane, acetonitrile, tetrahydrofuran, and diglyme, and these may be used in mixtures. The amount of solvent used is usually 50 to 1000% by mass, preferably 100 to 500% by mass, relative to the polyhydric phenol compound represented by formula (PH1).

[0033] Furthermore, in the glycidylation reaction of (Step 2), quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, and trimethylbenzylammonium chloride can also be used as catalysts. In this case, the amount of quaternary ammonium salt used is usually 0.001 to 0.2 moles, preferably 0.05 to 0.1 moles, per mole of hydroxyl groups of the polyhydric phenol compound represented by formula (PH1).

[0034] The reaction mixture containing the epoxy compound (EP1) obtained through steps (1) and (2) above can be isolated by post-treatment operations such as neutralization, washing with water, crystallization, filtration, drying, and distillation after the reaction is complete, according to conventional methods. To further increase the purity of the epoxy compound (EP1), it may be purified by distillation, recrystallization, or column chromatography according to conventional methods.

[0035] [Second Embodiment] The compound in the second embodiment is a polyhydric phenol compound represented by formula (PH1). This compound represented by formula (PH1) is a precursor of the compound represented by formula (EP1) in the first embodiment.

[0036] [ka]

[0037] In equation (PH1), n represents the number of repetitions of the structure in parentheses and is an integer greater than or equal to 1. Preferably, n is between 1 and 20, more preferably between 1 and 15, and even more preferably between 1 and 10. Multiple R 1 Allies, R 2 Allies, R 3 Allies, R 4 Allies, R 5 Allies, R 6 Allies, R 7 Fellow, and R 8 They are identical to each other, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 These are independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of alkyl groups having 1 to 3 carbon atoms include the methyl group, ethyl group, n-propyl group, and iso-propyl group. X is an alkylene group (-(CH2)) with 2 to 6 carbon atoms. p-, p=2~6). Examples of alkylene groups having 2 to 6 carbon atoms include ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, etc. Preferably, n-propylene, n-butylene, and n-pentylene, more preferably n-butylene and n-pentylene, and even more preferably n-pentylene.

[0038] In one embodiment, the compound represented by formula (PH1) is a single compound where n is the number of repeating units in parentheses. When it is a single compound, n in formula (PH1) is, for example, an integer from 1 to 10, preferably an integer from 1 to 5, more preferably 1 or 2, and even more preferably 1.

[0039] In a preferred embodiment, the compound represented by formula (PH1) is a mixture of various compounds with different numbers of repeating units n in parentheses. When it is a mixture, the average value of n in formula (PH1) is, for example, 1 to 10, preferably 1 to 9, and more preferably 1 to 8.

[0040] In one embodiment, the epoxy compound of the present invention is R in formula (PH1). 1 , R 2 , R 3 , and R 4 At least one of them is an alkyl group having 1 to 3 carbon atoms, and the rest are hydrogen atoms, and R in formula (EP1) 5 , R 6 , R 7 , and R 8 It has a structure in which at least one of the atoms is an alkyl group with 1 to 3 carbon atoms, and the rest are hydrogen atoms.

[0041] In one embodiment, the epoxy compound of the present invention is R in formula (PH1). 1 , R 2 , R 3 , and R 4 One of them is an alkyl group with 1 to 3 carbon atoms, and the remaining three are hydrogen atoms, and R in formula (1) 5 , R 6 , R 7 , and R 8It has a structure in which one of the elements is an alkyl group and the remaining three are hydrogen atoms.

[0042] In a preferred embodiment, the epoxy compound of the present invention is R in formula (PH1). 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 It has a structure in which all of its atoms are hydrogen atoms.

[0043] The method for producing the polyhydric phenol compound (PH1) in this embodiment is not particularly limited, and depending on the target polyhydric phenol compound, the starting material can be selected and known reaction steps / methods can be used. For example, the epoxy compound of this embodiment can be produced using a biphenyl compound represented by formula (BP) and a compound represented by formula (2) as starting materials, by the following (Step 1). (Step 1) A step in which a polyhydric phenol compound represented by formula (BP) is reacted with a compound represented by formula (2) to obtain a compound represented by formula (PH1). Note that this (Step 1) is the same as (Step 1) in the first embodiment. The resulting reaction product can be purified and isolated by the same post-treatment process as described above. [Examples]

[0044] The present invention will be described in more detail below with reference to examples.

[0045] (Example A1) Intermediate compound A, represented by formula (PH1-1), was synthesized using the following procedure. [ka]

[0046] 16.8 parts by weight of 3,3'-dimethyl-4,4'-dihydroxybiphenyl (manufactured by Honshu Chemical Co., Ltd.) and 26.5 parts by weight of 30% sodium hydroxide aqueous solution were mixed with 50.2 parts by weight of methanol and heated to 60°C. 6.4 parts by weight of 1,4-dibromobutane were slowly added dropwise over 2 hours, and the mixture was stirred at 60°C for 4 hours after the completion of the addition. The precipitate was filtered off, washed with 500 mL of pure water, the pH was adjusted with hydrochloric acid to approximately 6, and then washed again with 500 mL of pure water to obtain intermediate A as a white solid in 78% yield. The structure of intermediate A is as follows: 1 This was confirmed by H-NMR data. Furthermore, GPC measurement of intermediate A confirmed that intermediate A is a mixture with n>4 at 5.1%, n=3 at 8.4%, n=2 at 22.7%, and n=1 at 66.4% in terms of polystyrene UV equivalent.

[0047] 1 H-NMR(400MHz,DMSO-d6):9.11(s,2H,OH),7.31(m,8H,Ar-H),6.87(m,4H,Ar-H),4.07(m,4H,O- CH 2-CH2),2.18(d,J=10Hz,12H,Ar- CH 3), 1.93(m,4H,O-CH2- CH 2)

[0048] (Example A2) The compound represented by formula (EP1-1) was synthesized using the following procedure. [ka]

[0049] 19.6 parts by weight of intermediate A obtained in Example A1, 0.2 parts by weight of tetrabutylammonium chloride, 37.5 parts by weight of epichlorohydrin, and 36.5 parts by weight of dimethyl sulfoxide were added and the mixture was stirred for 1 hour while heating at 40°C. 3 parts by weight of 50% aqueous sodium hydroxide solution was slowly added dropwise, and after the addition was complete, the mixture was heated to 50°C and stirred for 1 hour. 6 parts by weight of 50% sodium hydroxide were then slowly added dropwise, and the temperature was raised to 90°C. After heating and stirring at 90°C for 6 hours, the mixture was cooled, and tetrahydrofuran was added to filter out the insoluble matter. The filtrate was washed with pure water and decanted. The recovered brownish viscous solid was dissolved in tetrahydrofuran, dried over magnesium sulfate, and the solvent was removed by distillation to obtain the target compound as a light brown solid in 72% yield. The structure of the obtained compound is as follows: 1 This was confirmed by 1H-NMR data. The weight-average molecular weight of this compound, calculated using GPC in terms of polystyrene UV, was 750.

[0050] 1 H-NMR(400MHz,DMSO-d6):7.34(m,8H,Ar-H),6.97(m,4H,Ar-H),4.31(m,2H,CH2),4.09(m,4H,O- CH 2-CH2),3.94(m,2H,CH2),3.33(m,2H,CH),2.83(m,2H,CH2),2.73(m,2H,CH2),2.21(d,J=9.2Hz,12H,Ar-CH3),1.95(m,4H,O-CH2-CH2)

[0051] (Examples 1-6, Comparative Examples 1-2) (Measurement of thermal conductivity) In Examples 1 to 6, the epoxy resin, curing agent, and curing accelerator obtained in Example A2 were melted and mixed on a hot plate at 150°C in the proportions shown in Table 1, cooled to room temperature, and pulverized to obtain a thermosetting resin composition. The prepared mixture was then subjected to either (Condition 1) compression molding at 150°C / 2MPa / 15 minutes followed by heat treatment in a 180°C oven for 3 hours, or (Condition 2) compression molding at 180°C / 2MPa / 15 minutes followed by heat treatment in a 180°C oven for 3 hours to produce a cured product. The obtained cured product was processed into a 10mm square x approximately 1mm thick sample to prepare a sample for thermal diffusivity measurement. In Comparative Examples 1 and 2, thermosetting resin compositions were prepared using the epoxy resin, curing agent, and curing accelerator shown in Table 1, in the same manner as in the above examples, and samples for thermal diffusivity measurement were prepared. The obtained samples were blackened using a graphite coating spray, manufactured by ULVAC. The thermal diffusivity at room temperature was measured using TD-1. The results are shown in Table 1.

[0052] Details of the components shown in Table 1 are as follows. (Epoxy resin) • Epoxy resin 1: The epoxy compound obtained in Example A2 above. • Epoxy resin 2: Biphenyl-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YX-4000HK)

[0053] (Hardening agent) • Hardener 1: Cyanate resin (Lonza, Primaset "PT-30") • Hardener 2: Pyromellitic anhydride (PMDA) (manufactured by Tokyo Chemical Industry Co., Ltd.) • Hardener 3: 4,4'-diaminodiphenylmethane (DDM) (manufactured by Tokyo Chemical Industry Co., Ltd.) • Hardener 4:4,4'-diaminodiphenylsulfone (DDS) (manufactured by Tokyo Chemical Industry Co., Ltd.) • Hardener 5: Phenolic novolac resin (manufactured by Sumitomo Bakelite Co., Ltd.)

[0054] (Curing accelerator) • Curing accelerator 1:2-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.)

[0055] Table 1

Claims

1. A compound represented by formula (EP1), 【Chemistry 1】 In formula (EP1), n represents the number of repetitions of the structure within the parentheses, and is an integer greater than or equal to 1. One of R1, R2, R3, and R4 is an alkyl group having 1 to 3 carbon atoms, and the remaining three are hydrogen atoms; one of R5, R6, R7, and R8 is an alkyl group having 1 to 3 carbon atoms, and the remaining three are hydrogen atoms. X is an alkylene group having 2 to 6 carbon atoms. Y is a base represented by formula (ep), 【Chemistry 2】 A compound in formula (ep) where r is an integer between 1 and 3.

2. The compound according to claim 1, wherein n in formula (EP1) is 1.

Images