JP2011190340A - Crosslinked resin composition and process for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition having both thermal conductivity and an insulation property in high levels, and less likely to exhibit anisotropy of a coefficient of thermal conductivity even in fabrication under shear such as injection molding. <P>SOLUTION: The crosslinked resin composition includes (A) a conductive nanofiller, (B) a crosslinked resin, and resins (C) other than the crosslinked resin (B). The crosslinked resin composition includes a dispersed phase formed from the crosslinked resin (B) and a continuous phase formed from the other resins (C), in which the conductive nanofiller (A) is present in the dispersed phase, and when assuming the ratio of the dispersed phase based on the whole crosslinked resin composition as X (unit: vol.%), and the ratio of a conductive nanofiller (A<SB>dsp</SB>) contained in the dispersed phase based on the total conductive nanofiller (A) as Y (unit: vol.%), Y is 20 vol.% or more and Y/X is 1.1 or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a crosslinked resin composition containing a conductive nanofiller and a method for producing the same.

  Conductive nanofillers typified by carbon nanofillers are excellent in thermal conductivity, electrical conductivity, mechanical properties, etc., so they are added to resins to impart or improve these properties. It is being considered. For example, Japanese Unexamined Patent Application Publication No. 2003-342480 (Patent Document 1) discloses a conductive thermoplastic elastomer composition in which carbon nanotubes are dispersed in a thermoplastic elastomer material in which a rubber is blended with a thermoplastic elastomer. This conductive thermoplastic elastomer composition is prepared by first blending rubber with a thermoplastic elastomer, dynamically crosslinking the rubber, and dispersing carbon nanotubes in the resulting thermoplastic elastomer material. Thus, although the electrical conductivity could be improved relatively easily by the addition of conductive nanofillers such as carbon nanotubes, it was not easy to significantly improve the thermal conductivity.

  Therefore, as a resin composition with improved thermal conductivity, Japanese Patent Application Laid-Open No. 2005-54094 (Patent Document 2) discloses heat conduction in which carbon such as fibrous carbon is dispersed in two or more kinds of resin mixtures. Resin materials have been proposed. In this resin material, thermal conductivity is enhanced by selectively dispersing carbon only in one resin phase to form a heat conduction path made of carbon. Japanese Patent Laying-Open No. 2005-54095 (Patent Document 3) discloses a conductive resin material in which carbon such as fibrous carbon is dispersed in two or more kinds of resin mixtures. In this conductive resin material, electrical conductivity is enhanced by selectively dispersing carbon in only one type of resin phase to form an electrical conduction path made of carbon. That is, the resin materials described in Patent Documents 1 and 2 have the same composition, and a path made of carbon acts as both a heat conduction path and an electrical conduction path, and both thermal conductivity and electrical conductivity are improved. For this reason, this resin material cannot be applied to applications that require thermal conductivity (heat dissipation) and insulation.

  JP 2005-150362 A (Patent Document 4) discloses a high thermal conductive sheet in which a thermal conductive filler such as carbon nanotube is dispersed in a thermoplastic resin which is a general-purpose resin. It is also disclosed to disperse an electrically insulating material such as alumina in order to suppress the electrical conductivity of the sheet and prevent electrical shorts. However, even when an electrically insulating material such as alumina is dispersed in a high thermal conductive sheet in which carbon nanotubes are dispersed, a high degree of insulation is not achieved, and the anisotropy of the thermal conductivity of the high thermal conductive sheet is large. Further, when a large amount of these electrically insulating materials having a large specific gravity is added in order to improve the insulating properties, the specific gravity of the sheet tends to increase or the molding processability and toughness tend to decrease. In applications such as various parts for moving media and various parts for electrical and electronic equipment, especially for various resin parts for automobiles, weight reduction and higher functionality of materials from the viewpoint of reducing carbon dioxide emissions and saving energy Accordingly, there has been a demand for a resin material that has both thermal conductivity and insulating properties while suppressing an increase in specific gravity and maintaining good moldability.

JP 2003-342480 A JP 2005-54094 A JP 2005-54095 A JP 2005-150362 A

  The present invention has been made in view of the above-mentioned problems of the prior art, has both high thermal conductivity and insulating properties, and also has different thermal conductivity even in processing under shear such as injection molding. It is an object of the present invention to provide a resin composition that is less likely to exhibit a directivity and a method for producing the same.

  As a result of intensive studies to achieve the above object, the present inventors have found that in the crosslinked resin composition containing the conductive nanofiller, the crosslinked resin, and other resins other than the crosslinked resin, FIG. 1A to FIG. The components of each phase in the figure depict the main components, and the components in each phase of the crosslinked resin composition of the present invention are not limited to this.) By forming a phase structure composed of a dispersed phase and a continuous phase, it is possible to prevent an electrical short circuit, the crosslinked resin composition has a high level of thermal conductivity and insulation, and further, under shear The present inventors have found that the thermal conductivity anisotropy is difficult to develop even in this processing, and have completed the present invention.

That is, the crosslinked resin composition of the present invention is a crosslinked resin composition containing a conductive nanofiller (A), a crosslinked resin (B), and another resin (C) other than the crosslinked resin (B),
The crosslinked resin composition comprises a dispersed phase formed from the crosslinked resin (B) and a continuous phase formed from the other resin (C).
In the dispersed phase, the conductive nanofiller (A) exists,
The ratio of the dispersed phase to the whole crosslinked resin composition is X (unit: volume%), and the ratio of the conductive nanofiller (A _dsp ) contained in the dispersed phase to the total conductive nanofiller (A) is Y. When (unit: volume%), Y is 20 volume% or more, and Y / X is 1.1 or more.

Moreover, the manufacturing method of the crosslinked resin composition of this invention is the crosslinked resin composition containing other resin (C) other than electroconductive nano filler (A), crosslinked resin (B), and this crosslinked resin (B). A manufacturing method of
It includes a crosslinking step of crosslinking (preferably dynamic crosslinking) the precursor of the crosslinked resin (B) in the presence of the conductive nanofiller (A).

In such a method for producing a crosslinked resin composition, in the crosslinking step, at least a part of the conductive nanofiller (A) and at least a part of the precursor of the crosslinked resin (B) are mixed and obtained. After kneading the resulting mixture to crosslink the precursor of the crosslinked resin (B),
It is preferable to mix a mixture of the conductive nanofiller (A) and the cross-linked resin (B) obtained in the cross-linking step and the other resin (C).

  In the cross-linking step, a mixture containing the conductive nanofiller (A), the precursor of the cross-linked resin (B) and the other resin (C) is kneaded to obtain a precursor of the cross-linked resin (B). The body may be cross-linked.

  In the present invention, the other resin (C) is preferably a thermoplastic resin. The conductive nanofiller (A) is preferably an anisotropic conductive nanofiller. The cross-linked resin composition of the present invention preferably further contains a compatibilizing agent (D).

In such a crosslinked resin composition of the present invention, it is preferable that the thermal conductivity in the thickness direction of a molded product having a thickness of 2 mm measured by a steady method is 0.3 W / mK or more. Moreover, it is preferable that the volume resistivity of the 2 mm-thick molded article, measured under the conditions of an applied voltage of 500 V and an applied time of 1 minute in accordance with JIS K6911, is 10 ¹³ Ω · cm or more.

  In addition, as shown to FIG. 1A-FIG. 1C, the crosslinked resin composition of this invention containing electroconductive nano filler (A), crosslinked resin (B), and other resin (C) other than this crosslinked resin (B) is shown. The reason for the phase structure consisting of a dispersed phase containing a conductive nanofiller and a continuous phase formed of other resins is not necessarily clear, but the present inventors speculate as follows. That is, the crosslinked resin composition of the present invention is obtained by subjecting the crosslinked resin precursor composition containing the conductive nanofiller (A), the precursor of the crosslinked resin (B) and the other resin (C) to a crosslinking treatment. Manufactured. In the crosslinked resin precursor composition, a dispersed phase is formed by the precursor of the crosslinked resin (B), and a continuous phase is formed by another resin, and the conductive nanofiller (A) is dispersed in the dispersed resin precursor composition. It is presumed that they are selectively incorporated into phases and are unevenly distributed (localized). When the crosslinked resin precursor composition having such a phase structure is subjected to a crosslinking treatment, the precursor of the crosslinked resin (B) is crosslinked with the conductive nanofiller (A) incorporated therein. In the composition, it is presumed that a phase structure in which the conductive nanofiller (A) 1 is unevenly distributed (localized) is formed in the dispersed phase 2 as shown in FIGS. 1A to 1C.

  On the other hand, when conductive nanofiller (A) is added to a mixture of cross-linked resin (B) (the precursor is subjected to cross-linking treatment) and other resin (C), conductive nanofiller (A ) Is difficult to be taken into the crosslinked resin (B), so that the conductive nanofiller (A) 1 is not unevenly distributed (localized) in the dispersed phase 2 and dispersed in the continuous phase 3 as shown in FIG. It is presumed to exist.

The reason why the crosslinked resin composition of the present invention has a high level of thermal conductivity and insulation by forming a phase structure as shown in FIGS. 1A to 1C is not necessarily clear. The inventors speculate as follows. That is, generally, when a conductive nanofiller is added to a crosslinked resin, thermal conductivity is improved. Furthermore, in the crosslinked resin composition of the present invention, the conductive nanofiller (A) 1 is confined in the dispersed phase 2, and the conductive nanofiller (A _dsp ) 1 in the dispersed phase 2 contains other dispersed phases. Since it is difficult to contact the conductive nanofiller (A) in the inside or the continuous phase 3 and it is difficult to form an electric conduction path, it is presumed that the thermal conductivity can be improved without significantly reducing the insulation. The

  On the other hand, in the crosslinked resin composition having a phase structure as shown in FIG. 2, since the conductive nanofiller (A) 1 is dispersed in the continuous phase 3, the conductive nanofiller (A) is in contact with other conductive nanofillers (A). It is easy to form an electric conduction path. As a result, in such a crosslinked resin composition, although the thermal conductivity is improved, it is presumed that the volume resistivity is lowered and the insulating property is lowered.

  Furthermore, although the reason why the crosslinked resin composition of the present invention is less likely to exhibit anisotropy of thermal conductivity even in processing under shear is not necessarily clear, the present inventors speculate as follows. . That is, in the crosslinked resin composition of the present invention, since the conductive nanofiller (A) is unevenly distributed (localized) in the dispersed phase 2, the conductive nanofiller (A) is subjected to processing under shear such as injection molding. It is presumed that the orientation of the filler (A) can be reduced, and the anisotropy of various properties such as thermal conductivity due to the orientation of the conductive nanofiller (A) can be reduced.

  On the other hand, in the crosslinked resin composition having a phase structure as shown in FIG. 2, since the conductive nanofiller (A) 1 is dispersed in the continuous phase 3, when processing under shear such as injection molding is performed. It is presumed that the conductive nanofiller (A) is oriented and anisotropy of various characteristics such as thermal conductivity is developed.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to obtain the crosslinked resin composition which has heat conductivity and insulation at a high level, and also is hard to express the anisotropy of thermal conductivity even in the process under shear. .

It is a schematic diagram which shows one embodiment of the crosslinked resin composition of this invention containing an electroconductive nanofiller. It is a schematic diagram which shows the other embodiment of the crosslinked resin composition of this invention containing an electroconductive nanofiller. It is a schematic diagram which shows the other embodiment of the crosslinked resin composition of this invention containing an electroconductive nanofiller. It is a schematic diagram which shows the state of the conventional crosslinked resin composition containing an electroconductive nanofiller.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, the crosslinked resin composition of the present invention will be described. The crosslinked resin composition of the present invention contains a conductive nanofiller (A), a crosslinked resin (B), and another resin (C) other than the crosslinked resin (B). In this crosslinked resin composition, a dispersed phase is formed by the crosslinked resin (B), and a continuous phase is formed by the other resin (C). The conductive nanofiller (A) is present in the dispersed phase.

  First, the conductive nanofiller (A), the crosslinked resin (B) and the other resin (C) used in the present invention will be described.

(A) Conductive nanofiller The conductive nanofiller (A) used in the present invention is not particularly limited. For example, it is coated with a carbon-based nanofiller, a metal-based nanofiller, and a metal or a conductive polymer. Nano fillers are preferred. These conductive nanofillers may be used alone or in combination of two or more. Among such conductive nanofillers, anisotropic conductive nanofillers are preferable from the viewpoint of improving thermal conductivity and mechanical strength, and anisotropic carbon-based nanofillers and anisotropic metal-based nanofillers are preferred. Are more preferable, and anisotropic carbon-based nanofillers are particularly preferable.

  The carbon-based nanofiller is not particularly limited. For example, carbon nanofiber, carbon nanohorn, carbon nanocone, carbon nanotube, carbon nanocoil, carbon microcoil, carbon nanowall, carbon nanochaplet, fullerene, graphite, graphene , Carbon nanoflakes, and derivatives thereof. These carbon-based nanofillers may be used alone or in combination of two or more. Among such carbon-based nanofillers, from the viewpoint of improving thermal conductivity and mechanical strength, carbon nanofibers, carbon nanohorns, carbon nanocones, carbon nanotubes, carbon microcoils, carbon nanocoils, carbon nanowalls, carbon nanos Anisotropic carbon-based nanofillers such as chaplet, graphite and graphene are more preferable, and from the viewpoint of further improving thermal conductivity, carbon nanofiber, carbon nanohorn, carbon nanocone, carbon nanotube, carbon nanocoil, carbon nanowall and Carbon nanochaplets are more preferred, carbon nanofibers and carbon nanotubes are particularly preferred, and carbon nanotubes are most preferred.

  The shape of such a carbon-based nanofiller may be a single trunk or a dendritic shape in which a large number of carbon-based nanofillers grow outward like branches. From the viewpoint of improvement in strength and the like, a single trunk is preferable. The carbon-based nanofiller may contain atoms, molecules, etc. other than carbon, and may contain a metal or other nanostructure as necessary.

In the present invention, among the peaks of the Raman spectrum obtained by measuring the carbon-based nanofiller with a Raman spectrophotometer, the G band observed in the vicinity of about 1585 cm ⁻¹ due to the displacement vibration of the carbon atom in the graphene structure. The ratio (G / D) of the D band observed in the vicinity of about 1350 cm ⁻¹ where there is a defect such as a dangling bond in the graphene structure is not particularly limited. In applications requiring conductivity, 0.1 or more is preferable, 1.0 or more is more preferable, 3.0 or more is more preferable, 5.0 or more is particularly preferable, and 10.0 or more is most preferable. When G / D is less than the lower limit, thermal conductivity tends not to be sufficiently improved.

  The aspect ratio of the anisotropic carbon-based nanofiller is not particularly limited. However, when mixed with a resin, mechanical strength such as tensile strength and impact strength, and thermal conductivity of the crosslinked resin composition can be improved by adding a small amount. 3 or more is preferable, 5 or more is more preferable, 10 or more is more preferable, 40 or more is particularly preferable, and 80 or more is most preferable.

  In addition, when carbon nanotubes and / or carbon nanofibers are used as the conductive nanofiller (A), either single-layer or multi-layer (two or more layers) can be used. Can be used together.

  For such carbon-based nanofillers, a conventionally known production method such as a chemical vapor deposition method (CVD method) such as a laser ablation method, an arc synthesis method, a HiPco process, or a melt spinning method should be appropriately selected according to the application. However, it is not limited to those manufactured by these methods.

Examples of the metal-based nanofiller used in the present invention include metal fillers and fillers of metal compounds such as metal oxides and metal hydroxides. Although there is no restriction | limiting in particular as a metal which comprises such a metal type nano filler, For example, silver, copper, gold | metal | money, brass, aluminum, iron, platinum, tin, magnesium, molybdenum, rhodium, zinc, palladium, tungsten, chromium Cobalt, nickel, titanium, metallic silicon, and alloys thereof are preferable. Among these metals, from the viewpoint of improving moldability, a low melting point metal (for example, Sn), a low melting point metal compound (for example, SnO ₂ ), a tin-based alloy (for example, Sn / Ag, Sn / Cu, Low melting point alloys such as Sn / Zn, Sn / Bi, Pb / Sn, Pb / Sn / Bi, Pb / Sn / Ag) and Pb / Ag are preferable. From the viewpoint of improving thermal conductivity, silver, copper, gold, brass, aluminum, iron, platinum, tin, and alloys and oxides thereof are preferable. Furthermore, in addition to the thermal conductivity, such a metal can impart a function specific to each metal (for example, antibacterial action in the case of silver) to the crosslinked resin composition.

  The shape of such a metal-based nanofiller is not particularly limited, and examples thereof include granular, flat plate, rod, fiber, tube, etc. Among them, from the viewpoint of improving thermal conductivity, flat plate, An anisotropic shape such as a rod shape, a fiber shape, and a tube shape is preferable.

  In addition, the nanofiller coated with a metal or a conductive polymer used in the present invention is not particularly limited, for example, glass beads coated with a metal such as silver, copper, gold, polyaniline, polypyrrole, polyacetylene, Examples thereof include glass beads coated with a conductive polymer such as poly (paraphenylene), polythiophene, or polyphenylene vinylene.

  In the present invention, the conductive nanofiller (A) includes a carboxyl group, a nitro group, an amino group, an alkyl group, an organic silyl group in the structure of the conductive nanofiller such as the carbon nanofiller or the metal nanofiller. Substituents such as groups, polymers such as poly (meth) acrylic acid esters, those in which the conductive polymers are introduced by chemical bonding, and those in which the conductive nanofillers are coated with other conductive materials Can be used.

  The average diameter of the conductive nanofiller (A) used in the present invention is not particularly limited, but is preferably 1000 nm or less, more preferably 500 nm or less, further preferably 300 nm or less, particularly preferably 200 nm or less, and most preferably 100 nm or less. preferable. When the average diameter of the conductive nanofiller (A) exceeds the upper limit, even if the conductive nanofiller (A) is added to the resin, the addition of a small amount does not sufficiently improve the thermal conductivity, the bending elastic modulus, etc. The mechanical strength tends to be insufficient. In addition, although there is no restriction | limiting in particular as a lower limit of the average diameter of electroconductive nanofiller (A), 0.4 nm or more is preferable and 0.5 nm or more is more preferable.

  In the crosslinked resin composition of the present invention, the lower limit of the content of the conductive nanofiller (A) is not particularly limited, but is preferably 0.1% by mass or more, and 0.3% by mass with respect to the entire crosslinked resin composition. % Or more is more preferable, 0.5 mass% or more is more preferable, 0.7 mass% or more is particularly preferable, and 1.0 mass% or more is most preferable. When the content of the conductive nanofiller (A) is less than the lower limit, the thermal conductivity and mechanical strength tend to decrease. The upper limit of the content of the conductive nanofiller (A) is not particularly limited as long as the insulating property can be maintained, but is preferably 50% by mass or less and more preferably 40% by mass or less with respect to the entire crosslinked resin composition. 30% by mass or less is more preferable, 20% by mass or less is particularly preferable, and 10% by mass or less is most preferable. If the content of the conductive nanofiller (A) exceeds the upper limit, the molding processability of the resulting crosslinked resin composition tends to decrease.

  In the crosslinked resin composition of the present invention, such a conductive nanofiller (A) is usually present localized in the dispersed phase, but a part thereof may be present in the continuous phase. .

(B) Crosslinked resin In the crosslinked resin composition of the present invention, the crosslinked resin (B) means a resin having a crosslinked structure at least partially, and the precursor (B1) of the crosslinked resin (B) (hereinafter, “ Cross-linked resin precursor (B1) ”) is obtained by cross-linking treatment. The crosslinked resin precursor (B1) is not particularly limited as long as it can form a crosslinked structure with a crosslinking agent or an electron beam, but is preferably an elastomer, natural rubber, polyisoprene, polybutadiene, styrene-butadiene. Rubber, styrene-butadiene-styrene copolymer (SBS), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), ethylene-butene rubber, ethylene-octene rubber, propylene-butene rubber, isoprene-butylene rubber, polyisobutylene, Isobutene-isoprene rubber (butyl rubber), chloroprene rubber, chlorosulfonated polyethylene, halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), acrylonitrile-butadiene-styrene rubber, methacrylic acid Rubbers such as ru-acrylonitrile-butadiene-styrene resin, urethane rubber, epichlorohydrin rubber, silicone rubber, fluorine rubber, polysulfide rubber, norbornene rubber, acrylic rubber; syndiotactic 1,2-polybutadiene, styrene-ethylenebutylene-styrene copolymer Thermoplastic elastomers such as polymer (SEBS), styrene-ethylenepropylene-styrene copolymer (SEPS), styrene-ethylene-ethylenepropylene-styrene copolymer (SEEPS); carboxyl group-modified styrene-butadiene rubber, hydroxyl group-modified styrene-butadiene Modified rubber such as rubber, carboxyl group hydroxyl group-modified styrene-butadiene rubber, carboxyl group-terminated butadiene-nitrile rubber (CTBN), hydroxyl group-terminated butadiene-nitrile rubber Modified elastomer and the like; hydrogenated nitrile rubber, hydrogenated rubber such hydrogenated CTBN; such as hydrogen thermoplastic elastomers such as hydrogenated syndiotactic 1,2-polybutadiene is more preferable. These elastomers may be used alone or in combination of two or more. Of these elastomers, rubber (rubber, modified rubber and hydrogenated rubber) is more preferable from the viewpoint of excellent crosslinkability, EPM and EPDM are more preferable, and EPDM is particularly preferable.

  There is no restriction | limiting in particular as dienes used for the said EPDM, A well-known thing can be used, 5-ethylidene-2-norbornene, 1, 4-hexadiene, dicyclopentadiene etc. are mentioned. Further, as the EPDM, it is preferable to use an oil-extended type.

  There is no restriction | limiting in particular as a crosslinking method of such a crosslinked resin precursor (B1), A crosslinked resin (B) can be formed by using a crosslinking agent or irradiating an electron beam. Especially, it is preferable to use a crosslinking agent (B2) from a viewpoint of the improvement of a crosslinking degree. Such a crosslinking agent (B2) is not particularly limited. For example, sulfur, peroxide, sulfur-containing organic compound, alkylphenol / formaldehyde condensate, brominated alkylphenol / formaldehyde condensate, alkylphenol / sulfur chloride condensate Such resin-based cross-linking agents. Such a crosslinking agent may be used individually by 1 type, or may use 2 or more types together. Among such cross-linking agents, as the resin-based cross-linking agent, alkylphenol / formaldehyde condensate (“Tactrol 201” manufactured by Taoka Chemical Co., Ltd.) and brominated alkylphenol / formaldehyde condensate (“Tacrol® manufactured by Taoka Chemical Co., Ltd.) are used. 250-III ").

  As addition amount of a crosslinking agent (B2), 0.1-20 mass parts is preferable with respect to 100 mass parts of crosslinked resin (B) obtained, and 0.2-15 mass parts is more preferable. Moreover, in order to accelerate | stimulate a crosslinking reaction, it is preferable to bridge | crosslink in presence of a well-known crosslinking accelerator and crosslinking promotion adjuvant (for example, zinc oxide).

  The crosslinking method is not particularly limited, but it is preferable to dynamically crosslink the crosslinked resin precursor (B1) by kneading (more preferably melt kneading) using an extruder. Thereby, the crosslinked resin composition excellent in heat conductivity and insulation is obtained.

  In the cross-linked resin (B) obtained by subjecting the cross-linked resin precursor (B1) to a cross-linking treatment in this way, it is preferable that the part connected by the cross-linking bond forms a cross-linked network structure and contains a gel component. However, it may contain an uncrosslinked portion. Although there is no restriction | limiting in particular as a gel fraction of the said crosslinked resin (B), 1 mass% or more is preferable from a viewpoint that the crosslinked resin composition obtained has heat conductivity and insulation at a high level, and 10 mass% or more is preferable. Is more preferably 50% by mass or more, particularly preferably 70% by mass or more, and most preferably 80% by mass or more.

In addition, in this invention, a gel fraction represents the ratio (%) of the part which has the cross-linking which occupies in the said crosslinked resin (B). In the present invention, this gel fraction is a value determined by the following method. That is, 200 mg of the pellet-shaped crosslinked resin composition is weighed and cut into 0.5 mm × 0.5 mm × 0.5 mm strips. This strip is immersed in 30 ml of cyclohexane at 23 ° C. for 48 hours to elute soluble components. The obtained solution is filtered to remove the soluble components, and the resulting residue is subjected to vacuum drying treatment (room temperature, 72 hours or more) until no mass decrease is confirmed, and the mass of the residue after drying is measured. did. The mass of cyclohexane insoluble components (conductive nanofiller (A), other resin (C), compatibilizer (D), etc.) other than the cross-linked resin (B) is calculated from the blending ratio of each component, The value obtained by subtracting the mass of the cyclohexane insoluble component from the mass is defined as the mass (y) of the portion having a crosslink in the cross-linked resin (B). Moreover, the mass of the cyclohexane soluble component other than the crosslinked resin (B) is calculated from the blending ratio of each component, and the mass of the cyclohexane soluble component and the mass of the cyclohexane insoluble component are calculated from the mass of the crosslinked resin composition (200 mg). The value obtained by subtracting the value is the mass (x) of the crosslinked resin (B). Therefore, the gel fraction (cyclohexane insoluble content) of the crosslinked resin (B) in the crosslinked resin composition is expressed by the following formula:
Gel fraction (mass%) of cross-linked resin (B) = y / x × 100
It is calculated by.

  In the crosslinked resin composition of the present invention, the lower limit of the content of the crosslinked resin (B) is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more, based on the entire crosslinked resin composition. 10 mass% or more is still more preferable, 20 mass% or more is especially preferable, and 30 mass% or more is the most preferable. The upper limit of the content of the crosslinked resin (B) is not particularly limited as long as the dispersed phase is formed by the crosslinked resin (B), but is preferably 95% by mass or less, more preferably 92% by mass or less, A mass% or less is particularly preferred. When the content of the cross-linked resin (B) is less than the lower limit, the thermal conductivity and the insulating properties tend not to be sufficiently improved. On the other hand, when the content exceeds the upper limit, the insulating properties tend to be lowered.

(C) Other resin In this invention, other resin (henceforth "other resin (C)") other than the said crosslinked resin (B) is used. The other resin (C) is not particularly limited as long as it is a resin other than the resin used as the crosslinked resin (B) and the crosslinked resin (B) forms a dispersed phase, but the crosslinked resin (B) From the viewpoint of easily forming a dispersed phase, epoxy resin, phenol resin, melamine resin, thermosetting imide resin, thermosetting polyamideimide, thermosetting silicone resin, urea resin, unsaturated polyester resin, urea resin, benzoguanamine Thermosetting resins such as resins, alkyd resins and urethane resins; aromatic vinyl resins such as polystyrene, acrylonitrile-styrene resins, methyl methacrylate-acrylonitrile-styrene resins, polymethyl methacrylate, polymethyl acrylate, polymethacrylic acid, Acrylic resins such as these copolymers, polyacrylo Toluyl, vinyl cyanide resin such as acrylonitrile-methyl acrylate resin, imide ring-containing vinyl resin, polyolefin resin such as polyethylene, polypropylene, polyisoprene, and cyclic polyolefin, ethylene-vinyl acetate copolymer (EVA), ethylene-methyl Ethylene copolymer such as methacrylate copolymer, ethylene-methyl acrylate copolymer, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl terephthalate, polyarylate, liquid crystal polyester, polyphenylene ether, polyarylene Sulfide, polysulfone, polyethersulfone, polyoxymethylene, polytetrafluoroethylene, polylactic acid, polysalt Vinyl, thermoplastic polyimide, thermoplastic polyamide-imide, polyether imide, polyether ether ketone, polyether ketone ketone, a thermoplastic resin such as polyether amide. Such resin may be used individually by 1 type, or may use 2 or more types together.

  Of these resins, a thermoplastic resin is preferable from the viewpoint of moldability, and among them, from the viewpoint of improving thermal conductivity and mechanical strength, for example, polyolefin resins such as polyethylene, polypropylene, polyisoprene, Polyamide, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl terephthalate, liquid crystal polyester, polyarylene sulfide, polyoxymethylene, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, polyvinylidene fluoride and polyfluoride More preferred are fluororesins such as vinyl fluoride, and crystalline resins such as polylactic acid, polyether ether ketone, polyether ketone ketone, and polyether amide. Further, from the viewpoint that the surface appearance of the molded body is excellent and the insulation is improved, an ethylene-based copolymer is preferable, and in particular, the viewpoint that the obtained crosslinked resin composition has a higher level of thermal conductivity and insulation. Therefore, it is preferable to use the ethylene copolymer and another resin in combination as the other resin (C).

  In the crosslinked resin composition of the present invention, the upper limit of the content of the other resin (C) is not particularly limited, but is preferably 10% by mass or more, more preferably 14% by mass or more based on the entire crosslinked resin composition. Preferably, 20% by mass or more is more preferable, 25% by mass or more is particularly preferable, 30% by mass or more is most preferable, 98% by mass or less is preferable, 96% by mass or less is more preferable, and 94% by mass or less is more preferable. 90 mass% or less is particularly preferable, and 85 mass% or less is most preferable. When the content of the other resin (C) is less than the lower limit, the insulating property tends to be lowered. On the other hand, when the content exceeds the upper limit, the thermal conductivity tends to be lowered.

(D) Compatibilizing agent The cross-linking resin composition of the present invention preferably contains a compatibilizing agent (D). Thereby, the crosslinked resin composition which has heat conductivity and insulation at a higher level is obtained. Such a compatibilizing agent (D) is not particularly limited as long as the compatibility of the dispersed phase formed by the crosslinked resin (B) and the continuous phase formed by the other resin (C) is improved. Known compatibilizers showing affinity and / or reactivity with at least one of (B) and other resins (C) may be mentioned, depending on the cross-linked resin (B) and other resins (C) used It is selected appropriately.

  For example, when EPDM is used as the cross-linked resin precursor (B1) and polypropylene is used as the other resin (C), the compatibilizer (D) is an olefin crystal-ethylene-butylene-olefin crystal block copolymer. Polymer (CEBC), styrene-ethylene-butylene-olefin crystal block copolymer (SEBC), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), styrene- Ethylene propylene-styrene copolymer (SEPS), ethylene-butylene copolymer (EBM), butene-1 copolymer (butene-ethylene copolymer, butene-propylene copolymer, etc.), propylene-α-olefin copolymer Polymer (propylene-ethylene copolymer, propylene Emissions copolymer) and the like are preferable. Such compatibilizers may be used alone or in combination of two or more. Among such compatibilizers, the compatibility between the dispersed phase and the continuous phase is further improved, the thermal resistance of these interfaces is further reduced, and the thermal conductivity of the crosslinked resin composition is further improved, From the viewpoint of further improving the insulating properties of the interface, CEBC is particularly preferable.

  Other resins (C) having a reactive functional group such as a terminal reactive group (for example, epoxy resin, polyamide, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl terephthalate, liquid crystal polyester, poly In the case of using arylene sulfide, polyoxymethylene, polylactic acid, etc.), a compatibilizer capable of forming a chemical bond with these resins is preferable from the viewpoint of further improving thermal conductivity. By adding such a compatibilizing agent, a stable layer is formed at the interface between the dispersed phase and the continuous phase, and the conductive nanofiller (A) can be stably encapsulated in the dispersed phase. . Moreover, it is more preferable that the compatibilizers (D) react with each other at the interface between the dispersed phase and the continuous phase. As a result, the layer formed at the interface between the dispersed phase and the continuous phase becomes thicker and stronger, and the conductive nanofiller (A) is effectively included in the dispersed phase, and the insulation is further improved. However, the thermal resistance of the interface tends to be further reduced (thermal conductivity is further improved).

  Examples of the compatibilizer (D) capable of reacting with such other resins (C) include alkoxysilyl groups, epoxy groups, isocyanate groups, amino groups, hydroxyl groups, mercapto groups, ureido groups, carboxyl groups, oxetane groups, and oxazolines. Those having at least one functional group selected from the group consisting of groups are preferred. As a method of introducing such a functional group into the compatibilizer (D), a method of copolymerizing a functional group-containing vinyl monomer such as glycidyl (meth) acrylate, (meth) acrylic acid, maleic anhydride; radical Examples thereof include a method of graft polymerization of a functional group-containing vinyl monomer in the presence of an initiator.

  In the crosslinked resin composition of the present invention, the content of the compatibilizing agent (D) is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more with respect to the entire crosslinked resin composition. More preferably, 0.1% by mass or more is further preferable, 0.2% by mass or more is particularly preferable, 60% by mass or less is preferable, 50% by mass or less is more preferable, 40% by mass or less is further preferable, and 20% by mass. % Or less is particularly preferable. If the content of the compatibilizing agent (D) is less than the lower limit, the insulating property tends not to be sufficiently ensured. On the other hand, if the content exceeds the upper limit, the moldability of the crosslinked resin composition tends to be lowered.

(E) Filler In the crosslinked resin composition of the present invention, a filler (E) may be contained as necessary. Thereby, the intensity | strength, rigidity, heat resistance, thermal conductivity, etc. of the obtained crosslinked resin composition can be improved. Such filler (E) may be fibrous or non-fibrous such as granular. Specific examples thereof include glass fibers, carbon fibers, metal fibers, aramid fibers, cellulose fibers, asbestos, potassium titanate whiskers, wollastonite, glass flakes, glass beads, talc, clay minerals represented by montmorillonite, mica (mica) ) Layered silicates represented by minerals and kaolin minerals, silica, calcium carbonate, magnesium carbonate, silicon oxide, calcium oxide, zirconium oxide, calcium sulfate, barium sulfate, titanium oxide, aluminum oxide and dolomite. The content of the filler (E) in the cross-linked resin composition of the present invention cannot be defined unconditionally because it varies depending on the type of the filler, but for example, 0.05% by mass or more with respect to the entire cross-linked resin composition Preferably, 0.1 mass% or more is more preferable, 1 mass% or more is more preferable, 90 mass% or less is preferable, 80 mass% or less is more preferable, 70 mass% or less is further preferable, and 60 mass% or less is preferable. Particularly preferred.

  Moreover, the crosslinked resin composition of the present invention may contain a heat conductive filler as the filler (E). Such a thermally conductive filler is not particularly limited, and examples thereof include alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, crystalline silica, fused silica, diamond, and zinc oxide. There is no restriction | limiting in particular as these shapes, For example, granular, flat form, rod shape, fiber shape, tube shape etc. are mentioned. These thermally conductive fillers may be used alone or in combination of two or more. Although there is no restriction | limiting in particular as thermal conductivity of this heat conductive filler, 0.5 W / mK or more is preferable, 1 W / mK or more is more preferable, 5 W / mK or more is further more preferable, 10 W / mK or more is especially preferable, Most preferable is 20 W / mK or more.

  Although the content rate of the heat conductive filler in the crosslinked resin composition of the present invention is not particularly limited, it is preferably 0.1% by mass or more, preferably 90% by mass or less, and 80% by mass with respect to the entire crosslinked resin composition. % Or less is more preferable, 70 mass% or less is more preferable, 50 mass% or less is especially preferable, and 40 mass% or less is the most preferable. If the content of the heat conductive filler is less than the lower limit, the thermal conductivity of the resulting molded product tends not to be sufficiently improved. On the other hand, if the content exceeds the upper limit, the specific gravity of the crosslinked resin composition increases and the fluidity is increased. It tends to decrease.

(Other additives)
The crosslinked resin composition of the present invention includes a conductive material such as carbon black, polyaniline, polypyrrole, polyacetylene, poly (paraphenylene), polythiophene and polyphenylene vinylene, and a filler coated with the conductive material. Can also be included. Although there is no restriction | limiting in particular as addition amount of such a conductive substance and the filler coat | covered with a conductive substance, It exists in the range which can maintain insulation (The volume resistivity is preferably 10 < ¹³ > ohm * cm or more). Is preferred. In addition, the dispersion state of the conductive material and the filler coated with the conductive material is not particularly limited. However, from the viewpoint of obtaining the effect of the addition of these while maintaining the insulating property, at least one of these is preferable. Is preferably contained in the dispersed phase formed by the crosslinked resin (B), and more than half of the added amount is contained in the dispersed phase formed by the crosslinked resin (B). More preferred.

  Further, the crosslinked resin composition of the present invention includes other components such as metal salt stabilizers such as copper chloride, cuprous iodide, copper acetate, cerium stearate, hindered amines, hindered phenols, and sulfur-containing compounds. Antioxidants and heat stabilizers such as compound-based, acrylate-based, and phosphorus-based organic compounds, UV absorbers and weathering agents such as benzophenone-based, salicylate-based, and benzotriazole-based materials, light stabilizers, mold release agents, lubricants, crystal nuclei Agents, viscosity modifiers, colorants, surface treatment agents such as silane coupling agents, pigments, fluorescent pigments, dyes, fluorescent dyes, anti-coloring agents, plasticizers, flame retardants (red phosphorus, metal hydroxide flame retardants, Phosphorus flame retardants, silicone flame retardants, halogen flame retardants, and combinations of these halogen flame retardants with antimony trioxide), wood powder, rice bran powder, walnut powder, waste paper Phosphorescent pigments, antibacterial agents and antifungal agents such as boric acid glass and silver-based antibacterial agent, magnesium - may be added to a mold corrosion inhibitor such as hydrotalcite represented by aluminum hydroxy hydrate.

<Method for producing crosslinked resin composition>
Next, the manufacturing method of the crosslinked resin composition of this invention is demonstrated. The manufacturing method of the crosslinked resin composition of this invention includes the process (crosslinking process) of bridge | crosslinking a crosslinked resin precursor (B1) in presence of an electroconductive nanofiller (A). As such a production method, for example, in the crosslinking step, the conductive nanofiller (A), the crosslinked resin precursor (B1), the other resin (C), and, if necessary, the compatibilizer (D) In the crosslinking step, the filler (E) and other additives are mixed together and then subjected to crosslinking treatment on the crosslinked resin precursor (B1) (hereinafter referred to as “first production method”); After preparing a mixture of the conductive nanofiller (A) and the crosslinked resin precursor (B1) in advance, the crosslinked resin precursor (B1) is subjected to crosslinking treatment, and the obtained conductive nanofiller (A) and Method of mixing the mixture with the cross-linked resin (B) and the remaining components (other resin (C) and, if necessary, compatibilizer (D), filler (E), other additives) (Hereinafter referred to as “second manufacturing method”) . Among such production methods, the second production method is preferred from the viewpoint that the phase structure according to the present invention is suitably formed and the resulting crosslinked resin composition has both high thermal conductivity and insulating properties. .

  The method for mixing each component in the first production method is not particularly limited. For example, kneading with an extruder, Banbury mixer, rubber roll machine, ultrasonic treatment in a solvent, high-speed stirrer or mill ( For example, stirring by a ball mill or the like, dry blending and the like can be mentioned, and among them, melt kneading is preferable. Moreover, when mixing thermosetting resin as other resin (C), it is preferable to use a self-revolving mixer or to perform ultrasonic treatment.

  Moreover, there is no restriction | limiting in particular as a method of preparing the mixture of an electroconductive nano filler (A) and a crosslinked resin precursor (B1) in said 2nd manufacturing method, For example, by an extruder, a Banbury mixer, a rubber roll machine, etc. Kneading, ultrasonic treatment in a solvent, stirring with a high-speed stirrer or a mill (for example, a ball mill), dry blending, synthesis of a crosslinked resin precursor (B1) in the presence of a conductive nanofiller (A) (in situ) Among them, melt kneading is preferable.

  In the second production method, when the conductive nanofiller (A) and the crosslinked resin precursor (B1) are mixed, at least a part of the conductive nanofiller (A) and the crosslinked resin precursor (B1) After mixing at least a part first, the remaining conductive nanofiller (A) and the crosslinked resin precursor (B1) may be added and mixed, but the predetermined amount of the crosslinked resin precursor (B1) It is preferable to first mix 50% or more of the conductive nanofiller (A), and then add and mix the remaining conductive nanofiller (A). It is particularly preferable to mix the fixed amount of the crosslinked resin precursor (B1) at once.

  In the first and second production methods, the method for crosslinking the crosslinked resin precursor (B1) is not particularly limited, and examples thereof include heat treatment and electron beam irradiation. Among these, the crosslinked resin precursor (B1) is used. From the viewpoint of improving the thermal conductivity and insulation of the resulting crosslinked resin composition. Further, from the viewpoint that the mixing of the components and the crosslinking of the crosslinked resin precursor (B1) can proceed simultaneously, the mixture containing the crosslinked resin precursor (B1) can be melt-kneaded at a predetermined temperature. preferable.

  In the second production method, the method of mixing the mixture of the crosslinked resin (B) and the conductive nanofiller (A) after the crosslinking treatment and the remaining components is not particularly limited. For example, an extruder or Examples include kneading with a Banbury mixer, rubber roll machine, etc., ultrasonic treatment (when liquid), stirring with a high-speed stirrer or a mill (for example, ball mill), dry blending, etc. Among them, melt kneading is preferable. Moreover, when mixing thermosetting resin as other resin (C), it is preferable to use a self-revolving mixer or to perform ultrasonic treatment.

  Furthermore, in the second production method, the conductive nanofiller (A) and the crosslinked resin precursor (B1) are introduced from a hopper upstream of an extruder equipped with one or more side feeders, and melt kneaded. Then, the cross-linked resin precursor (B1) is cross-linked, and the remaining components are added simultaneously or independently from the side feeder into the kneaded product of the obtained conductive nanofiller (A) and the cross-linked resin (B). It is preferable to melt and knead. Of the remaining components, the filler (E) and other additives are side feeders downstream from the charging port for charging the other resin (C) from the viewpoint of improving mechanical properties and thermal conductivity. In addition, it is preferable to use a single screw extruder or a screw arrangement with a weak kneading ability in a melt-kneaded product containing conductive nanofiller (A), cross-linked resin (B) and other resin (C). It is also preferable to add the last using a twin screw extruder.

  The extruder used in such a first or second production method is not particularly limited as long as it has sufficient kneading ability, and examples include those having a uniaxial or multiaxial vent.

  In the method for producing a crosslinked resin composition of the present invention, the shape of each component is not particularly limited, and any shape such as pellets, powders, and strips may be used. In addition, a solvent can be used when a high-speed stirrer or a mill is used or when ultrasonic treatment is performed. In this case, in order to remove the solvent from the obtained mixture, it is preferable to perform post-treatment such as reprecipitation, filtration and drying. Furthermore, when the shape of the obtained mixture is a lump, it is preferable to perform a grinding process.

<Crosslinked resin composition>
As described above, the crosslinked resin composition of the present invention thus prepared includes a dispersed phase formed by the crosslinked resin (B) and a continuous phase formed by the other resin (C). The conductive nanofiller (A) is present in the dispersed phase. This tends to improve thermal conductivity and insulation. In the crosslinked resin composition of the present invention, the dispersed phase means a portion where the crosslinked resin (B) is surrounded by other resins (C).

Although there is no restriction | limiting in particular as thermal conductivity of the crosslinked resin composition of this invention provided with such a phase structure, The thermal conductivity of the thickness direction measured by the stationary method about the molded object of thickness 2mm is 0.3 W / It is preferably mK or more, more preferably 0.4 W / mK or more, particularly preferably 0.5 W / mK or more, and most preferably 0.6 W / mK or more. The volume resistivity is not particularly limited, but the volume resistivity measured for a molded product having a thickness of 2 mm in accordance with JIS K6911 under the conditions of an applied voltage of 500 V and an applied time of 1 minute is 10 ¹³ Ω · cm or more. It is preferably 10 ¹⁴ Ω · cm or more, more preferably 10 ¹⁵ Ω · cm or more, and most preferably 10 ¹⁶ Ω · cm or more.

1A to 1C schematically show the phase structure of such a crosslinked resin composition, but the phase structure of the crosslinked resin composition of the present invention is not limited thereto. The disperse phase 2 is formed by the crosslinked resin (B). However, as long as the disperse phase 2 and the continuous phase 3 are formed, other resins having affinity with the conductive nanofiller (A) Other resin (C) may be contained. There is no particular limitation on the number of conductive nanofillers (A _dsp ) 1 included in one dispersed phase 2, and one may be used as shown in FIG. Good. Furthermore, when there are a plurality of conductive nanofillers (A _dsp ) 1 in the dispersed phase 2, the dispersion state is not particularly limited, and the conductive nano fillers (A _dsp ) 1 are in contact even if they are in contact with each other 1B, it may be completely isolated and dispersed as shown in FIG. 1B, or may be completely in contact with each other as shown in FIG. 1C, but the thermal conductivity anisotropy is reduced. From this viewpoint, it is preferable that the major axis direction of each conductive nanofiller (A _dsp ) 1 exists more three-dimensionally. In the crosslinked resin composition of the present invention, two or more states among the states shown in FIGS. 1A to 1C may be mixed. The shape of the dispersed phase 2 is not particularly limited, and may be a perfect circle or a non-circular shape such as a stripe shape, a polygonal shape, or an elliptical shape.

The continuous phase 3 is formed of the other resin (C). However, as long as the dispersed phase 2 and the continuous phase 3 are formed, the crosslinked resin (B) may be included. The continuous phase 3 may contain the conductive nanofiller (A). However, in applications where insulation is required, the content of the continuous phase 3 is the insulation (volume resistivity of the crosslinked resin composition). Preferably, it is in a range where 10 ¹³ Ω · cm or more is maintained.

  In the crosslinked resin composition of the present invention, it is preferable that a compatibilizing agent (D) is present at the interface between the dispersed phase 2 and the continuous phase 3. Thereby, the compatibility of the disperse phase 2 and the continuous phase 3 is improved, the thermal resistance of the interface is further reduced, the thermal conductivity of the crosslinked resin composition is further improved, and the insulating property of the interface is further improved. There is a tendency.

  Moreover, in the case where a resin having a reactive functional group such as a terminal reactive group is used as at least one of the crosslinked resin (B) and the other resin (C), from the viewpoint of improving thermal conductivity. The compatibilizer (D) preferably forms a chemical bond with the cross-linked resin (B) and / or the other resin (C). Thereby, a stable layer is formed at the interface between the dispersed phase 2 and the continuous phase 3, and the conductive nanofiller (A) can be stably encapsulated in the dispersed phase 2. Further, at the interface between the dispersed phase 2 and the continuous phase 3, it is more preferable that the compatibilizers (D) react with each other. As a result, the layer formed at the interface between the dispersed phase 2 and the continuous phase 3 becomes thicker and stronger, and the conductive nanofiller (A) is effectively included in the dispersed phase 2 and has an insulating property. However, the thermal resistance of the interface tends to be further reduced (thermal conductivity is further improved).

The phase structure of such a crosslinked resin composition can be confirmed by observing with a scanning electron microscope or a transmission electron microscope. In the crosslinked resin composition of the present invention, the ratio of the dispersed phase to the entire crosslinked fat composition is X (unit: volume%), and the conductive nanofiller contained in the dispersed phase relative to the total conductive nanofiller (A). When the ratio of (A _dsp ) is Y (unit: volume%), the ratio (Y / X) is 1.1 or more. When the Y / X value is less than the lower limit, the insulating property is lowered. Further, from the viewpoint that the insulating property is easily improved, the Y / X value is preferably 1.2 or more, more preferably 1.3 or more, further preferably 1.4 or more, particularly preferably 1.5 or more. 0.0 or more is most preferable.

The ratio Y of the conductive nanofiller (A _dsp ) contained in the dispersed phase with respect to the total conductive nanofiller (A) is 20% by volume or more. When the ratio Y is less than the lower limit, the thermal conductivity and the insulating properties are lowered. Further, from the viewpoint of easy improvement in thermal conductivity and insulation, Y is preferably 40% by volume or more, more preferably 50% by volume or more, further preferably 60% by volume or more, particularly preferably 80% by volume or more, 100 Volume% is most preferred.

Furthermore, in the crosslinked resin composition of the present invention, the ratio Z of the dispersed phase containing the conductive nanofiller (A _dsp ) with respect to the entire crosslinked resin composition is not particularly limited, but is preferably 1% by volume or more and preferably 3 volumes. % Or more, more preferably 5% by volume or more, particularly preferably 7% by volume or more, most preferably 10% by volume or more, more preferably 85% by volume or less, more preferably 80% by volume or less, and 70% by volume. The following is more preferable, 60% by volume or less is particularly preferable, and 50% by volume or less is most preferable. When the ratio Z is less than the lower limit, the thermal conductivity and the insulating properties tend to decrease and the anisotropy of the thermal conductivity tends to increase. On the other hand, when the ratio exceeds the upper limit, the fluidity of the crosslinked resin composition decreases. There is a tendency.

  In the present invention, the values of X, Y, and Z are values obtained based on a scanning electron microscope (SEM) photograph as follows. That is, a molded product having a predetermined thickness is produced from the cross-linked resin composition of the present invention, and an arbitrary portion of the central portion (a range of 40 to 60% of the total thickness from the surface) of the molded product is scanned. Photographed using a scanning electron microscope (SEM) and developed on a photographic paper having a uniform thickness. In the obtained SEM photograph, the range of 90 μm × 90 μm is arbitrarily extracted at five locations in the size of the molded product. Measure the mass of this extracted range, cut out a predetermined part (conductive nanofiller, dispersed phase, etc.) from this extracted range, measure the mass of the photograph of the cut out part, and measure the mass ratio of the photo for the predetermined part (Mass%) is calculated. The mass ratio of this photograph can be regarded as the actual volume ratio (capacity%) of the predetermined portion because the thickness of the used photographic paper is uniform. This capacity ratio is obtained for any of the five extracted locations, and the average value is taken as the value of X, Y or Z (capacity%).

  In the crosslinked resin composition of the present invention, the number average value of the diameter or major axis of the dispersed phase is not particularly limited, but is preferably 50 nm or more, more preferably 100 nm or more, further preferably 500 nm or more, and particularly preferably 1 μm or more. Preferably, 2 μm or more is most preferable, 200 μm or less is preferable, and 100 μm or less is more preferable. If the number average value of the diameter or the major axis of the dispersed phase is less than the lower limit, the thermal conductivity and the insulating properties tend to decrease, and the thermal conductivity anisotropy tends to increase. There is a tendency for the mechanical strength of objects to decrease.

  In the present invention, the diameter or major axis of the disperse phase is a value obtained by conducting measurement by arbitrarily extracting five places of the size of the molded product in the electron micrograph, and measuring these measured values at five locations. It is.

  Although there is no restriction | limiting in particular as a method of processing such a crosslinked resin composition of this invention into a molded object, A melt molding process is preferable. Examples of the melt molding method include conventionally known molding methods such as injection molding, extrusion molding, blow molding, press molding, compression molding, and gas assist molding. In addition, the orientation of the conductive nanofiller (A), the crosslinked resin (B), and the other resin (C) can be controlled by applying a magnetic field, an electric field, an ultrasonic wave, or the like during the molding process.

  In addition, the crosslinked resin composition of the present invention hardly exhibits anisotropy in various properties (for example, thermal conductivity) even when processed under shear. Here, under shear means a state in which a force (shearing force) that causes displacement inside the object is applied, and examples of processing under shear include injection molding, extrusion molding, and blow molding. It is done. For example, when a cross-linked resin composition is injection molded, when the cross-linked resin composition is extruded from a nozzle of an injection molding machine, force is applied to the cross-linked resin composition in a direction parallel and opposite to the discharge direction (flow direction). Slip or shift occurs in a section of the composition. As a result, in the conventional crosslinked resin composition in which the conductive nanofiller (A) is not unevenly distributed (localized) in the dispersed phase, the conductive nanofiller (A) is oriented in the flow direction. Exhibits anisotropy in various properties (for example, thermal conductivity). On the other hand, in the crosslinked resin composition of the present invention, since the dispersed phase containing the conductive nanofiller (A) is dispersed in a three-dimensionally nearly uniform state, it is conductive even when subjected to processing under shear. The nanofiller (A) is difficult to be oriented, and in the resulting molded article, anisotropy is hardly exhibited in various characteristics (for example, thermal conductivity), and characteristics such as thermal conductivity are almost three-dimensionally uniform. There is a tendency.

  In addition, compared with injection molding, the shear force at the time of press molding is remarkably small, and in the press-molded product, the orientation of the conductive nanofiller and the resin is extremely small. For this reason, the anisotropy of various characteristics is extremely small in the press-formed product. Therefore, in the present invention, the ratio of the physical property value (for example, thermal conductivity) in the thickness direction of the injection molded product to the physical property value (for example, thermal conductivity) in the thickness direction of the press molded product is obtained, and this physical property value is obtained. The anisotropy of the characteristics (for example, thermal conductivity) expressed by the crosslinked resin composition is quantitatively evaluated by the ratio. For example, it can be said that a cross-linked resin composition having a property value ratio closer to 1 has a smaller anisotropy in properties such as thermal conductivity and is nearly three-dimensionally uniform.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In addition, the physical property of the obtained resin composition was measured with the following method.

(1) Volume resistivity After pellet-shaped resin composition was vacuum-dried at 80 degreeC for 12 hours, press molding was performed at 250 degreeC, and the molded article of thickness 2mm was obtained. A disc-shaped sample having a diameter of 100 mm and a thickness of 2 mm was cut out from this molded product, and 500 V was applied in accordance with JIS K6911 using a high resistance meter (“AGILENT 4339B” manufactured by Agilent Technologies) after 1 minute. Volume resistivity was measured.

(2) Thermal conductivity The pellet-shaped resin composition was vacuum-dried at 80 ° C. for 12 hours, and then press-molded at 250 ° C. to obtain a molded product having a thickness of 2 mm. A 25 mm × 25 mm × 2 mm sample was cut out from this molded article, and the sample was measured at 40 ° C. (upper / lower temperature difference of 24 ° C.) using a steady-state thermal conductivity measuring device (“GH-1” manufactured by ULVAC-RIKO). The thermal conductivity (W / mK) in the thickness direction was measured.

(3) Anisotropy of thermal conductivity The pellet-shaped resin composition was vacuum-dried at 80 ° C. for 12 hours, and then injection-molded under conditions of a molding temperature of 250 ° C. and a mold temperature of 50 ° C., and a molded product having a thickness of 2 mm. Got. A 25 mm × 25 mm × 2 mm sample was cut out from this molded article, and the sample was measured at 40 ° C. (upper / lower temperature difference of 24 ° C.) using a steady-state thermal conductivity measuring device (“GH-1” manufactured by ULVAC-RIKO). The thermal conductivity (W / mK) in the thickness direction was measured.

From the thermal conductivity (W / mK) in the thickness direction of this injection-molded product and the thermal conductivity (W / mK) in the thickness direction of the press-molded product measured in (2) above, the following formula:
Thermal conductivity anisotropy = (thermal conductivity in the thickness direction of the injection molded product) / (in the above (2)
(Measured thermal conductivity in the thickness direction of the press-formed product)
Thus, the anisotropy of thermal conductivity was obtained. In the press-formed product, there is almost no difference in the thermal conductivity between the thickness direction and the direction perpendicular thereto. Therefore, it can be said that the closer the ratio of thermal conductivity is to 1, the smaller the orientation of the conductive nanofiller in the flow direction during injection molding is, and the smaller the anisotropy is.

(4) Y / X value The pellet-shaped resin composition was vacuum-dried at 80 ° C for 12 hours, and then press-molded at 250 ° C to obtain a molded product having a thickness of 2 mm. A sample of 40 mm × 5 mm × 2 mm is cut out from this molded product, and an arbitrary portion of the central portion (portion in the range of 0.8 to 1.2 mm from the surface) of the frozen fracture surface at the center of this sample is scanned. Images were taken using a scanning electron microscope (SEM) and developed on photographic paper having a uniform thickness. In the obtained SEM photograph, the range of 90 μm × 90 μm was arbitrarily extracted at five locations in the size of the molded product. After measuring the mass of the photograph of the extracted range, a portion corresponding to the dispersed phase formed by the crosslinked resin (B) is cut out from the extraction range, the mass of the photograph of the cut-out portion is measured, The mass ratio (% by mass) of the photograph corresponding to the dispersed phase was calculated. The mass ratio of this photograph can be regarded as the volume ratio (volume%) of the dispersed phase with respect to the resin composition in the extraction range because the thickness of the photographic paper used is uniform. In the following Examples and Comparative Examples, the volume ratio of the dispersed phase was determined for any of the five extracted locations, and the average value was defined as the ratio X (unit: volume%) of the dispersed phase with respect to the entire resin composition. .

Further, SEM photography was performed in the same manner as described above, and arbitrary five locations (each in the range of 90 μm × 90 μm in size of the molded product) were extracted from the obtained SEM photograph. All the portions corresponding to the conductive nanofiller (A) were cut out from the photograph of the extracted range, and the total mass of the cut portion of the photograph was measured. Moreover, the mass of the photograph of the part corresponding to the conductive nanofiller (A _dsp ) contained in the dispersed phase among the part corresponding to the conductive nanofiller (A) is measured, and the total conductivity of the extraction range is measured. The mass ratio (mass%) of the photograph of the conductive nanofiller (A _dsp ) in the dispersed phase relative to the conductive nanofiller (A) was calculated. In this case as well, the mass ratio of the photograph is regarded as the volume ratio (capacity%) of the conductive nanofiller (A _dsp ) in the dispersed phase with respect to the total conductive nanofiller (A) in the extraction range. In the following examples and comparative examples, the volume fraction of the conductive nanofiller (A _dsp ) in the dispersed phase was determined for any of the five extracted locations, and the average value was calculated as the value in the resin composition. The ratio Y (unit: volume%) of the conductive nanofiller (A _dsp ) in the dispersed phase relative to the total conductive nanofiller (A) was used.

  The Y / X value was determined from the X and Y values thus calculated.

Moreover, each component of the electroconductive nano filler (A) used in the Example and the comparative example, the crosslinked resin (B), and other resin (C) are shown below. In addition, the G / D value of the following conductive nanofiller (A) is measured at an excitation laser wavelength of 532 nm using a laser Raman spectroscopy system [“NRS-3300” manufactured by JASCO Corporation], and is about 1585 cm ^−1. It was determined from the peak intensity of the Raman spectrum of the G band observed in the vicinity and the D band observed in the vicinity of about 1350 cm ⁻¹ .

(A) Conductive nanofiller:
-Conductive nanofiller (a-1)
Carbon nanofiber (“VGCF” manufactured by Showa Denko KK, average diameter 150 nm, aspect ratio 60, G / D value 9.6).
-Conductive nanofiller (a-2)
Multi-walled carbon nanotube (“MWNT-7” manufactured by Nanocarbon Technologies, Inc., diameter distribution 40 to 90 nm, aspect ratio 100 or more, G / D value 8.0).

(B1) Crosslinked resin precursor:
-Crosslinked resin precursor (b1-1)
Ethylene-propylene-diene rubber (“EPT3012” manufactured by Mitsui Chemicals, Inc.).

(B2) Crosslinking agent:
・ Crosslinking agent (b2-1)
sulfur.

(B3) Crosslinking accelerator:
・ Crosslinking accelerator (b3-1)
N-oxydiethylene-2-benzothiazolylsulfenamide (“Noxeller MSA-G” manufactured by Ouchi Shinsei Chemical Co., Ltd.).
・ Crosslinking accelerator (b3-2)
Tetramethylthiuram disulfide ("Noxeller TT" manufactured by Ouchi Shinsei Chemical Co., Ltd.).

(B4) Crosslinking accelerating aid:
・ Crosslinking accelerator (b4-1)
Zinc oxide (“Activated Zinc Hana Azo” manufactured by Shodo Chemical Industry Co., Ltd.).

(C) Other resins:
・ Resin (c-1)
Polypropylene ("Novatec PP MA3" manufactured by Nippon Polypro Co., Ltd.).
・ Resin (c-2)
Ethylene-vinyl acetate copolymer ("Novatech EVA" manufactured by Nippon Polychem Co., Ltd.).

(D) Compatibilizer:
・ Compatibilizer (d-1)
Olefin crystal-ethylenebutene-olefin crystal block copolymer ("DYNARON6200P" manufactured by JSR Corporation).

Example 1
Conductive nanofiller (a-1) 10 parts by mass, crosslinked resin precursor (b1-1) 70 parts by mass, crosslinking agent (b2-1) 0.5 parts by mass, crosslinking accelerator (b3-1) 0.5 A mass part, 0.5 mass part of a crosslinking accelerator (b3-2), 1 mass part of a crosslinking acceleration aid (b4-1), and 20 parts by mass of a resin (c-1) were blended, and the resulting mixture was A twin-screw melt kneading extruder equipped with a vent (manufactured by Technobel, screw diameter: 15 mm, L / D: 60) is charged and melt kneaded under the conditions of a cylinder set temperature of 230 ° C. and a screw rotation speed of 300 rpm. Dynamic crosslinking was performed. The discharged kneaded product was extruded into a strand shape, cooled and then cut with a cutter to obtain a pellet-shaped resin composition. About this resin composition, Y / X value, volume resistivity, thermal conductivity, and its anisotropy were measured according to the said method. The results are shown in Table 1.

(Example 2)
10 parts by mass of the conductive nanofiller (a-1) and 70 parts by mass of the crosslinked resin precursor (b1-1) were blended, and the resulting mixture was mixed with a twin-screw melt-kneading extruder (( Co., Ltd. “TEX30” manufactured by Nippon Steel Works, screw diameter: 30 mm, L / D: 77) from the most upstream hopper, melt kneading under conditions of cylinder set temperature 230 ° C., screw rotation speed 300 rpm, In this kneaded product, 0.5 part by mass of a crosslinking agent (b2-1), 0.5 part by mass of a crosslinking accelerator (b3-1), 0.5 part by mass of a crosslinking accelerator (b3-2), a crosslinking acceleration aid (B4-1) A mixture containing 1 part by mass and 20 parts by mass of resin (c-1) is charged from the side feeder and further melted and kneaded under conditions of a cylinder set temperature of 230 ° C. and a screw speed of 300 rpm. Cross-linked The discharged kneaded product was extruded into a strand shape, cooled and then cut with a cutter to obtain a pellet-shaped resin composition. About this resin composition, Y / X value, volume resistivity, thermal conductivity, and its anisotropy were measured according to the said method. The results are shown in Table 1.

(Examples 3 to 5)
A mixture of the conductive nanofiller (A) of the type and blending amount shown in Table 1 and the precursor (B1) of the crosslinked resin (B) is introduced from the hopper, and the crosslinking agent of the kind and blending amount shown in Table 1 ( B2), a crosslinking accelerator (B3), a crosslinking accelerator (B4), other resin (C) and a compatibilizer (D) were added in the same manner as in Example 2 except that the mixture was added from the side feeder. A pellet-shaped resin composition was obtained. About these resin compositions, Y / X value, volume resistivity, thermal conductivity, and the anisotropy were measured according to the said method. The results are shown in Table 1.

(Comparative Examples 1-3)
The types and blending amounts of the precursors (B1), crosslinking agents (B2), crosslinking accelerators (B3), crosslinking accelerators (B4), and other resins (C) shown in Table 1 The mixture is charged into a twin-screw melt kneading extruder equipped with a vent (manufactured by Technobell, screw diameter: 15 mm, L / D: 60), and melted under conditions of a cylinder set temperature of 230 ° C. and a screw rotation speed of 300 rpm. The mixture was kneaded and subjected to dynamic crosslinking. The discharged kneaded product was extruded into a strand shape, cooled and then cut with a cutter to obtain a pellet-shaped resin composition.

  The conductive nanofiller (a-1) having the blending amount shown in Table 1 is added to the pellet-shaped resin composition, and the obtained mixture is charged into the biaxial melt kneading extruder, and the cylinder set temperature 230 is set. Melt kneading was performed under the conditions of ° C and a screw rotation speed of 300 rpm. The discharged kneaded product was extruded into a strand shape, cooled and then cut with a cutter to obtain a pellet-shaped resin composition. About this resin composition, Y / X value, volume resistivity, thermal conductivity, and its anisotropy were measured according to the said method. The results are shown in Table 1.

  As is clear from the results shown in Table 1, the crosslinked resin composition of the present invention in which the precursor (B1) of the crosslinked resin (B) was dynamically crosslinked in the presence of the conductive nanofiller (A) (implementation) In Examples 1 to 5, the crosslinked resin (B) is compared with the case where the precursor (B1) of the crosslinked resin (B) is subjected to dynamic crosslinking and then the conductive nanofiller (A) is mixed (Comparative Examples 1 to 3). In the dispersed phase formed by (B), a large amount of conductive nanofiller (A) is unevenly distributed, which has a high level of thermal conductivity and insulation, and also has a different thermal conductivity even when injection molding is performed. It was difficult to develop the directionality.

  Moreover, when Example 2 and Example 1 are compared, after mixing electrically conductive nano filler (A) and the precursor (B1) of crosslinked resin (B), other resin (C) is added. When the precursor (B1) of the crosslinked resin (B) is subjected to dynamic crosslinking (Example 2), the conductive nanofiller (A) and the precursor (B1) of the crosslinked resin (B) and others It was found that the insulating property was improved and the anisotropy of thermal conductivity was less likely to be exhibited as compared with the case where the resin (C) was mixed together (Example 1).

  Furthermore, when Example 3 and Example 2 are compared, by adding the compatibilizing agent (D), the thermal conductivity and the insulating properties are further improved, and the anisotropy of the thermal conductivity is less likely to be exhibited. all right. This is presumably because the affinity of the interface between the dispersed phase formed of the cross-linked resin (B) and the continuous phase formed of the other resin (C) was improved by the compatibilizer (D). Moreover, when Example 4 and Example 3 are compared, thermal conductivity and insulation are further improved by using an ethylene copolymer in combination as the other resin (C), and the anisotropy of thermal conductivity is Further, it was found that the expression becomes difficult.

  As described above, according to the present invention, there is provided a crosslinked resin composition that has both high thermal conductivity and insulating properties, and that hardly exhibits anisotropy of thermal conductivity even in processing under shear. Can be obtained.

  Therefore, the crosslinked resin composition of the present invention is used in applications requiring thermal conductivity, heat dissipation, isotropic thermal conductivity, insulation, etc., for example, various parts for automobiles, various parts for electrical and electronic equipment, It is useful for applications such as high thermal conductivity sheets, heat sinks, and electromagnetic wave absorbers.

  1: conductive nanofiller (A), 2: dispersed phase (mainly cross-linked resin (B)), 3: continuous phase (mainly other resin (B)).

Claims (10)

It is a crosslinked resin composition containing a conductive nanofiller (A), a crosslinked resin (B), and other resin (C) other than the crosslinked resin (B),
The crosslinked resin composition comprises a dispersed phase formed from the crosslinked resin (B) and a continuous phase formed from the other resin (C).
In the dispersed phase, the conductive nanofiller (A) exists,
The ratio of the dispersed phase to the whole crosslinked resin composition is X (unit: volume%), and the ratio of the conductive nanofiller (A _dsp ) contained in the dispersed phase to the total conductive nanofiller (A) is Y. A cross-linked resin composition characterized in that Y is 20% by volume or more and Y / X is 1.1 or more when expressed as (unit: volume%).   The crosslinked resin composition according to claim 1, wherein the other resin (C) is a thermoplastic resin.   The crosslinked resin composition according to claim 1 or 2, wherein the conductive nanofiller (A) is an anisotropic conductive nanofiller.   The cross-linked resin composition according to any one of claims 1 to 3, further comprising a compatibilizer (D).   The cross-linking according to any one of claims 1 to 4, wherein the thermal conductivity in the thickness direction of a 2 mm-thick molded body, measured by a steady method, is 0.3 W / mK or more. Resin composition. The volume resistivity of a molded article having a thickness of 2 mm, measured under the conditions of an applied voltage of 500 V and an applied time of 1 minute in accordance with JIS K6911, is 10 ¹³ Ω · cm or more. The crosslinked resin composition as described in any one of them. A method for producing a crosslinked resin composition comprising a conductive nanofiller (A), a crosslinked resin (B), and another resin (C) other than the crosslinked resin (B),
A method for producing a crosslinked resin composition comprising a crosslinking step of crosslinking the precursor of the crosslinked resin (B) in the presence of the conductive nanofiller (A).   In the crosslinking step, the conductive nanofiller (A), the precursor of the crosslinked resin (B) and the mixture containing the other resin (C) are kneaded to crosslink the precursor of the crosslinked resin (B). The manufacturing method of the crosslinked resin composition of Claim 7 characterized by the above-mentioned. In the crosslinking step, at least a part of the conductive nanofiller (A) and at least a part of the precursor of the crosslinked resin (B) are mixed, and the obtained mixture is kneaded to mix the crosslinked resin (B). After crosslinking the precursor of
8. The crosslinked resin according to claim 7, wherein a mixture of the conductive nanofiller (A) and the crosslinked resin (B) obtained in the crosslinking step and the other resin (C) are mixed. A method for producing the composition.   The method for producing a crosslinked resin composition according to any one of claims 7 to 9, wherein the crosslinking is dynamic crosslinking.

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