JP2012021084A - Molded product obtained by heat curing thermosetting molding material - Google Patents

Abstract

The present invention provides a molded article having high thermal conductivity and excellent mechanical strength while having insulating properties.
The molded article of the present invention comprises a polybenzoxazine resin produced using phenols having two hydroxyphenyl groups, diamines, and aldehydes as raw materials, a thermally conductive filler having insulating properties, and Can be obtained by heat-curing a molding material containing a mass ratio of 5/95 to 50/50. Moreover, in this invention, it is preferable that 50 mol% or more of the phenols which have two hydroxyphenyl groups is 4,4'- biphenol.
[Selection figure] None

Description

  The present invention relates to a molded article obtained by heat-curing a thermosetting molding material containing a polybenzoxazine resin and a thermally conductive filler having insulating properties.

Recently, electronic products have been rapidly reduced in size, performance, and functionality. Along with this, measures for heat dissipation of circuit boards on which semiconductors and the like are mounted and electronic components on which various chips, devices, and the like are mounted have become important.
Specific examples of LED lighting, notebook PCs, LCD TVs, PDP TVs, mobile phones, digital cameras, game machines, DVD players, DVD recorders, Blu-ray players, Blu-ray recorders, car navigation systems, hybrid cars, electric cars, etc. This is a heat dissipation measure.

Conventionally, molded products of epoxy resin compositions containing thermally conductive fillers are excellent in heat resistance, mechanical strength, dimensional stability, etc. in use. In such a field, there is a problem that the performance of the component itself deteriorates due to heat generation of the component itself or use in a high temperature atmosphere, and it has been required to increase the thermal conductivity of the material.
To solve these problems, a method of improving the thermal conductivity of the material by using graphite or carbon fiber as a filler has been studied. However, since these base materials have conductivity, the insulation resistance is greatly reduced. Therefore, there is a problem that it is difficult to apply to electrical and electronic parts that require insulation.

  In addition, a filler having a high thermal conductivity having an insulating property such as silica powder or alumina powder may be used as the filler (see, for example, Patent Document 1), but a large amount of these fillers are used to increase the thermal conductivity. There is a problem that the mechanical strength is lowered, the fluidity of the material is lowered, the kneading workability and the moldability are impaired, so the melt viscosity before curing is higher than that of a conventional general phenol resin. Attempts have been made to ensure the fluidity of the material by using a low-flowing benzoxazine resin (see, for example, Patent Document 2 and Patent Document 3).

JP 2002-220507 A Japanese Patent Laid-Open No. 11-71498 JP 2001-64480 A

However, the benzoxazine resins described in Patent Document 2 and Patent Document 3 have insufficient mechanical strength. Moreover, it was difficult to have an insulating property and a thermal conductivity exceeding 2.5 W / m · K only with a high filler content.
An object of the present invention is to provide a molded article having high thermal conductivity and excellent mechanical strength.

  As a result of intensive studies, the present inventors have found that a molded product obtained by heat-curing a thermosetting molding material containing a polybenzoxazine resin having a specific chemical structure and a thermally conductive filler having an insulating property in a specific ratio. The knowledge that the said objective can be achieved was acquired.

[1] A polybenzo having a benzoxazine ring structure in the main chain, represented by the following formula (1), produced using phenols having two hydroxyphenyl groups, diamines, and aldehydes as raw materials An oxazine resin (in the formula (1), Ar ¹ represents an aromatic group, R ¹ represents an organic group, and n represents an integer of 2 or more) and a thermally conductive filler having insulating properties are mixed in a mass ratio. A molded article comprising heat-curing a molding material contained in a range of 5/95 to 50/50.

  [2] The molded article according to [1], wherein 50 mol% or more of the phenols having two hydroxyphenyl groups is 4,4′-biphenol.

  [3] The molded article according to [1] or [2], wherein the thermally conductive filler having an insulating property contains an alumina compound, magnesium oxide, and boron nitride.

  [4] The molded article according to [3], wherein the alumina compound is spherical.

  According to the present invention, a molded article having high thermal conductivity and excellent mechanical strength can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
The molded article of the present invention is obtained by heat-curing a molding material containing a polybenzoxazine resin described in the above formula (1) and a thermally conductive filler having insulating properties.
First, the polybenzoxazine resin described in the above formula (1) will be described.
The polybenzoxazine resin described in the above formula (1) is produced by reacting phenols having two hydroxyphenyl groups, diamines and aldehydes in an organic solvent.
The phenols having two hydroxyphenyl groups are represented by the following formula (2) and have a hydrogen that can be substituted in at least one ortho position with respect to carbon bonded to the hydroxyl group of the hydroxyphenyl group. There is no particular limitation. (In Formula (2), Ar ¹ represents an aromatic group.)
Examples of phenols having two hydroxyphenyl groups include bisphenol A, bisphenol F, bisphenol S, bisphenol E, bisphenol Z, 4,4′-dihydroxydiphenyl ether, 4,4′-biphenol, 4,4′-dihydroxybenzophenone, 4,4 ′-[1,3-phenylenebis (1-methyl-ethylidene)] bisphenol (“Bisphenol M” manufactured by Mitsui Chemicals Fine), 4,4 ′-[1,4-phenylenebis (1-methyl-ethylidene) )] Bisphenol (“Bisphenol P” manufactured by Mitsui Chemicals Fine) and the like may be mentioned, and these may be used alone or in combination of two or more. Moreover, as phenols which have two hydroxyphenyl groups, it is preferable that 50 mol% or more is 4,4′-biphenol because the thermal conductivity is improved.

The diamines are not particularly limited as long as they are represented by the following formula (3) and have amino groups at both ends, such as aromatic diamines, aliphatic diamines, and alicyclic diamines. (In Formula (3), R ¹ represents an organic group.)
As aromatic diamines, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 ′-[1,4 -Phenylenebis (1-methyl-ethylidene)] bisaniline, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene and the like, among others, 4,4′- Diaminodiphenylmethane and 4,4′-diaminodiphenyl ether are preferred because they are inexpensive.
Examples of the aliphatic diamine include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,8-octanediamine, and 1,10-decane. Examples include diamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,18-octadecanediamine and the like. Among them, ethylenediamine, 1,3-propanediamine, and 1,6-hexanediamine are inexpensive. preferable.
Furthermore, as other diamines, alicyclic diamines, diamines having unsaturated or branched hydrocarbon groups, and the like can also be used. Examples of the alicyclic diamine include 1,4-bis (aminomethyl) cyclohexane, 1,3-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexylamine), 4,4′-methylenebis (2-methyl). Cyclohexylamine), isophoronediamine, 1,3-diaminoadamantane, norbornanediamine and the like.
These diamines may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although it does not specifically limit as said aldehydes, For example, acetaldehyde, formaldehyde, etc. are mentioned, These may be used individually by 1 type and may be used in combination of 2 or more type. . Examples of the formaldehyde include paraformaldehyde and an aqueous solution of formaldehyde, but an aqueous solution of formaldehyde is preferable because of ease of synthesis.

  The reaction temperature and reaction time in the above reaction step are not particularly limited. Usually, polybenzoxazine is reacted in an organic solvent in the range of room temperature to 120 ° C. for several tens of minutes to several hours, and the organic solvent removal step is performed. A resin can be obtained.

  The organic solvent to be used is not particularly limited, but those having good solubility with respect to phenols and diamines having two hydroxyphenyl groups as raw materials and polybenzoxazine resin as a reaction product are preferable. . Examples of such solvents include halogen solvents such as chloroform and dichloromethane, ether solvents such as tetrahydrofuran and dioxane, aromatic solvents such as xylene and toluene, and ketone solvents such as methyl isobutyl ketone.

The polybenzoxazine resin of the above formula (1) thus obtained has a linear structure before curing compared to conventional phenol resins and benzoxazine resins. The product was found to have high mechanical strength.
Further, in the above formula (1), n is 2 or more, but n is preferably 5 or more because sufficient mechanical strength can be obtained.

Next, the thermally conductive filler having insulating properties contained in the molding material will be described. Examples of thermally conductive fillers having insulating properties include boron nitride, aluminum nitride, magnesium oxide, and alumina compounds (as alumina compounds, alumina, as well as kaolin, clay, mica, aluminum borate, vermiculite, smectite, and other Al _{2 materials.} And those containing an O ₃ component).
Among these, in the present invention, it is preferable to contain all three kinds of an alumina compound, magnesium oxide, and boron nitride because the thermal conductivity is improved. Furthermore, since the filling property is improved, the alumina compound is particularly preferably spherical.

  The thermosetting molding material preferably contains a mass ratio of the polybenzoxazine resin represented by the above formula (1) and the thermally conductive filler having insulation in a range of 5/95 to 50/50. If the polybenzoxazine resin is 5 parts by mass or more, sufficient strength can be obtained, and if it is 50 parts by mass or less, the thermal conductivity can be improved.

  The molding material for obtaining the molded article of the present invention may be various additives used in molding materials of conventional epoxy resin compositions as desired, for example, mold release agents such as calcium stearate and zinc stearate or Lubricants, silane coupling agents, and colorants such as carbon black can be added. Further, inorganic fillers such as calcium carbonate, barium sulfate, calcium sulfate, silica, pearlite, shirasu balloon, diatomaceous earth, calcium silicate, talc, glass fiber, potassium titanate fiber and the like may be used in combination.

In the present invention, a polybenzoxazine resin and a thermally conductive filler having an insulating property, and various additives and the like according to the purpose are blended in a predetermined amount, and these are mixed with a pressure kneader, a twin screw extruder, a Henschel mixer, and mixing. After heat-kneading with a hot roll or the like, the thermosetting resin molding material used for the molded product of the present invention can be produced by pulverization or pelletization.
The thermosetting resin molding material obtained in this way can produce a desired molded product using various molding methods such as compression molding and transfer molding.

  The molded product obtained in the present invention has insulation, high thermal conductivity, and excellent mechanical strength. Therefore, LED lighting, notebook PC, liquid crystal television, PDP television, mobile phone, digital camera, game It can be used for parts such as a computer, a DVD player, a DVD recorder, a Blu-ray player, a Blu-ray recorder, a car navigation system, a hybrid car, and an electric vehicle.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the characteristic of the obtained molded product was evaluated by the method shown below.
(1) Thermal conductivity Measured with a GH-1 rapid thermal conductivity meter manufactured by ULVAC-RIKO.
(2) Bending strength (mechanical strength)
Measured according to JIS K 6911.

[Resin Example 1]
(Synthesis of thermosetting resin (A-1))
Bisphenol A (34.2 g, 0.15 mol) and 4,4′-diaminodiphenylmethane (29.7 g, 0.15 mol) were added to methyl isobutyl ketone, and the temperature was raised to 80 ° C. After dropwise addition of 36.0 g (0.60 mol) of a 50% aqueous formaldehyde solution, the mixture was stirred for 30 minutes. Thereafter, the temperature was further raised, and the mixture was reacted for 3 hours under reflux. After the completion of the reaction, the reaction solution was evaporated with an evaporator to obtain a reaction product. Then, the polybenzoxazine resin (A-1) whose weight average molecular weight is 4000 was obtained by drying under reduced pressure at 80 degreeC.

[Resin Example 2]
(Synthesis of thermosetting resin (A-2))
Bisphenol A (34.2 g, 0.15 mol) and 1,6-hexanediamine (17.4 g, 0.15 mol) were added to methyl isobutyl ketone, and the temperature was raised to 80 ° C. After dropwise addition of 36.0 g (0.60 mol) of a 50% aqueous formaldehyde solution, the mixture was stirred for 30 minutes. Thereafter, the temperature was further raised, and the mixture was reacted for 3 hours under reflux. After the completion of the reaction, the reaction solution was evaporated with an evaporator to obtain a reaction product. Then, the polybenzoxazine resin (A-2) whose weight average molecular weight is 10,000 was obtained by drying under reduced pressure at 80 degreeC.

[Resin Example 3]
(Synthesis of thermosetting resin (A-3))
In dioxane, 22.3 g (0.12 mol) of 4,4′-biphenol, 18.2 g (0.08 mol) of bisphenol A, and 39.6 g (0.20 mol) of 4,4′-diaminodiphenylmethane were added. After being heated to 30 ° C. and dissolved, when the temperature was lowered to 30 ° C., 26.1 g (0.80 mol) of 92% formaldehyde was added and stirred at 90 ° C. Thereafter, the temperature was further raised and the reaction was carried out under reflux for 7 hours. After the completion of the reaction, the reaction solution was evaporated with an evaporator to obtain a reaction product. Then, polybenzoxazine resin (A-3) having a weight average molecular weight of 4500 was obtained by drying under reduced pressure at 80 ° C.

[Comparative resin example 1]
(Synthesis of thermosetting resin (B-1))
In methyl isobutyl ketone, 22.8 g (0.1 mol) of bisphenol A was added and completely dissolved, and then 18.6 g (0.2 mol) of aniline and 13.0 g (0.4 mol) of 92% formaldehyde were added. Stir at 85-90 ° C. Thereafter, the temperature was further raised and the reaction was carried out under reflux for 2 hours. After completion of the reaction, it was taken out after a vacuum desolvation dehydration step at −93.3 kPa or less to obtain a benzoxazine resin (B-1).

[Comparative resin example 2]
(Formulation of thermosetting resin (B-2))
A bisphenol A type epoxy resin (Japan Epoxy Resin, 1001) and a novolak type phenol resin (PSM-4324, manufactured by Gunei Chemical Industry Co., Ltd.) as a curing agent are kneaded at room temperature with a Henschel mixer, and a thermosetting resin (B- 2) was obtained.

[Example 1]
15 parts by mass of thermosetting resin (A-1) and 85 parts by mass of non-spherical alumina (manufactured by Nippon Light Metal Co., Ltd.) were kneaded at room temperature with a Henschel mixer to obtain a thermosetting resin molding material.
The obtained thermosetting resin molding material is transfer molded by a transfer molding machine under molding conditions of a mold temperature of 200 ° C., a curing time of 5 minutes, and a press pressure of 70 kg / cm ² , and a test piece for thermal conductivity measurement and bending. A test piece for strength measurement was prepared. The measurement results are shown in Table 1.

[Example 2]
Thermosetting resin (A-1) 15 parts by mass, non-spherical alumina (manufactured by Nippon Light Metal) 60 parts by mass, magnesium oxide (manufactured by Kyowa Chemical) 25 parts by mass are kneaded at room temperature with a Henschel mixer, and thermosetting resin molding material Got.
The obtained thermosetting resin molding material is transfer molded by a transfer molding machine under molding conditions of a mold temperature of 200 ° C., a curing time of 5 minutes, and a press pressure of 70 kg / cm ² , and a test piece for thermal conductivity measurement and bending. A test piece for strength measurement was prepared. The measurement results are shown in Table 1.

[Example 3]
15 parts by mass of thermosetting resin (A-1), 45 parts by mass of spherical alumina (manufactured by Electrochemical), 15 parts by mass of non-spherical alumina (manufactured by Nippon Light Metal), 18 parts by mass of magnesium oxide (manufactured by Kyowa Chemical), hexagonal nitriding 7 parts by mass of boron (hBN: Taiwan) was kneaded at room temperature with a Henschel mixer to obtain a thermosetting resin molding material.
The obtained thermosetting resin molding material is transfer molded by a transfer molding machine under molding conditions of a mold temperature of 200 ° C., a curing time of 5 minutes, and a press pressure of 70 kg / cm ² , and a test piece for thermal conductivity measurement and bending. A test piece for strength measurement was prepared. The measurement results are shown in Table 1.

[Example 4]
A test piece for measuring thermal conductivity and a test piece for measuring bending strength were prepared in the same manner as in Example 3 except that the thermosetting resin (A-1) was changed to the thermosetting resin (A-2). The measurement results are shown in Table 1.

[Example 5]
In the same manner as in Example 3 except that the thermosetting resin (A-1) was changed to the thermosetting resin (A-3), a test piece for measuring thermal conductivity and a test piece for measuring bending strength were prepared. The measurement results are shown in Table 1.

[Comparative Example 1]
In the same manner as in Example 3 except that the thermosetting resin (A-1) was changed to the thermosetting resin (B-1), a test piece for measuring thermal conductivity and a test piece for measuring bending strength were prepared. The measurement results are shown in Table 1.

[Comparative Example 2]
60 parts by mass of thermosetting resin (A-1), 21.2 parts by mass of spherical alumina (manufactured by Electrochemical), 7.0 parts by mass of non-spherical alumina (manufactured by Nippon Light Metal), 8.5 mg of magnesium oxide (manufactured by Kyowa Chemical) Part by mass and 3.3 parts by mass of hexagonal boron nitride (hBN: Taiwan) were kneaded at room temperature with a Henschel mixer to obtain a thermosetting resin molding material.
The obtained thermosetting resin molding material is transfer molded by a transfer molding machine under molding conditions of a mold temperature of 200 ° C., a curing time of 5 minutes, and a press pressure of 70 kg / cm ² , and a test piece for thermal conductivity measurement and bending. A test piece for strength measurement was prepared. The measurement results are shown in Table 1.

[Comparative Example 3]
Thermosetting resin (A-1) 3 parts by mass, spherical alumina (manufactured by Electrochemical) 51.4 parts by mass, non-spherical alumina (manufactured by Nippon Light Metal) 17.1 parts by mass, magnesium oxide (manufactured by Kyowa Chemical) 20.5 Part by mass and 8.0 parts by mass of hexagonal boron nitride (hBN: made in Taiwan) were kneaded at room temperature with a Henschel mixer to obtain a thermosetting resin molding material.
The obtained thermosetting resin molding material is transfer molded by a transfer molding machine under molding conditions of a mold temperature of 200 ° C., a curing time of 5 minutes, and a press pressure of 70 kg / cm ² , and a test piece for thermal conductivity measurement and bending. A test piece for strength measurement was prepared. The measurement results are shown in Table 1.

[Comparative Example 4]
In the same manner as in Example 3 except that the thermosetting resin (A-1) was changed to the thermosetting resin (B-2), a test piece for measuring thermal conductivity and a test piece for measuring bending strength were prepared. The measurement results are shown in Table 1.

From Table 1, Examples 1-5 which are the molded articles of the present invention all had a thermal conductivity exceeding 2.5 W / m · K and a bending strength of 80 MPa or more.
Moreover, in Example 3, Example 4 and 5, Example 4 whose 60 mol% of phenols which have two hydroxyphenyl groups used for the synthesis | combination of polybenzoxazine resin is 4,4'-biphenol, High thermal conductivity and high bending strength.
Furthermore, in Examples 1 to 3, Example 3 containing an alumina compound, magnesium oxide, and boron nitride as a thermally conductive filler having insulating properties has high thermal conductivity and high bending strength.
On the other hand, in Comparative Examples 1 to 4, no good results were obtained in both thermal conductivity and bending strength.

Claims (4)

A polybenzoxazine resin having a benzoxazine ring structure in the main chain represented by the following formula (1), produced by using phenols having two hydroxyphenyl groups, diamines, and aldehydes as raw materials ( In Formula (1), Ar ¹ represents an aromatic group, R ¹ represents an organic group, and n represents an integer of 2 or more), and a thermally conductive filler having insulating properties is a mass ratio of 5/95. A molded product comprising heat-curing a molding material contained in a range of -50/50.

  The molded article according to claim 1, wherein 50 mol% or more of the phenols having two hydroxyphenyl groups is 4,4'-biphenol.   The molded article according to claim 1 or 2, wherein the thermally conductive filler having an insulating property contains an alumina compound, magnesium oxide, and boron nitride.   4. The molded article according to claim 3, wherein the alumina compound is spherical.