JP5082304B2 - Thermally conductive resin material and molded body thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat conductive resin material that does not deteriorate practical performance such as original molding processability of a thermosetting resin, weight saving and mechanical strength, and has excellent heat conductivity and anisotropic heat conductivity controlling direction and movement of the heat conduction, and to provide a molded product using the resin material. <P>SOLUTION: This heat conductive resin material comprises a resin component containing a thermosetting resin (A) as a matrix material, an organic compound (B) immiscible with the resin component, and a fibrous filler (C). The organic compound (B) exists in the resin component as dispersed particles, and two or more fibrous fillers (C) come into contact with surfaces of each dispersed particles or exist in the dispersed particles. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a heat conductive resin material excellent in heat conductivity, mechanical strength, molding processability, antistatic property, and electromagnetic wave shielding property and a molded body thereof, and more specifically, a heat conductive resin containing carbon fiber. It relates to materials and molded products.

  Thermosetting resins have excellent mechanical properties, heat resistance, insulation, etc., so various types of insulation materials for electronic parts, exterior materials for small electronic devices, building materials, interior and exterior materials for aircraft and ships, etc. It is used as an important material in the industrial field. In particular, in electronic equipment applications, thermal conductivity for efficiently radiating heat generated from various devices is required, but thermosetting resins are generally not sufficient in thermal conductivity.

  On the other hand, as a method for improving the thermal conductivity of the resin, a method of adding a thermal conductive filler is generally known. For example, inorganic fillers with high thermal conductivity such as alumina, boron nitride, and carbon are widely used. In particular, carbon fiber is relatively cheap and toxic in addition to being lighter than other fillers. Since it has no impact on the environment, it has attracted attention as a material with excellent practicality.

  For example, in Patent Document 1, carbon fibers are included before the liquid crystalline reaction curable resin is cured, a magnetic field is applied, and the carbon fibers and the resin molecules are cured while being oriented in a certain direction, thereby causing heat in a specific direction. A resin molded body with improved conductivity has been reported.

  Patent Document 2 discloses that an isotropic structure unit containing mesogen is present in an epoxy resin in an amount of 25% by volume or more, and further an inorganic ceramic filler is contained in an amount of 20% by volume or more, thereby maintaining isotropicity as a whole. However, resin molded bodies with improved thermal conductivity have been reported.

  Further, in Patent Document 3, in a mixture of two or more kinds of thermoplastic resins, fibrous carbon having a diameter of 1 μm or less is unevenly distributed in one kind of resin phase, and a local high heat conduction region is formed so that the entire heat conduction is achieved. A resin molded body having improved properties has been reported.

  However, the resin molded bodies disclosed in Patent Documents 1 to 3 have several problems. In the molded article of Patent Document 1, the mechanical strength against stress and impact in a specific direction is significantly reduced by the orientation of carbon fibers and resin molecules. In other words, the mechanical properties of the resin molded product are largely dependent on the higher order structure of the resin molecules. When the resin molecules are oriented in a certain direction, the entanglement of the three-dimensional molecular chains is reduced, and the mechanical strength is reduced. It drops significantly. Furthermore, in order to apply a strong magnetic field in the molding process, special processing is required for the existing molding apparatus, and there is a great obstacle in practical use.

  On the other hand, in the molded article of Patent Document 2, a regular molecular structure is partially present to improve thermal conductivity. However, the continuity of thermal conduction between molecules is limited, and as a result, There arises a problem that it is necessary to rely on the addition of a filler. In fact, although the thermal conductivity of up to about 5 times is obtained by the introduction of mesogen, the value is about 1 W / m · K, and finally it becomes about 5 W / m · K by coexisting 40% by volume of filler. Is to improve. In a thermosetting resin molded body in which such a filler is highly blended, the mechanical strength is greatly reduced, and the inherent properties of the resin cannot be exhibited.

  Moreover, in the molded object of patent document 3, although the fibrous carbon is unevenly distributed in a specific resin phase and the thermal conductivity of the whole molded object is improved by forming a local heat conductive area | region, each resin is improved. Since the mechanical properties of the phases are different, the mechanical strength of the compact is greatly reduced. This is because interfacial breakage easily occurs between the resin phase in which fibrous carbon is unevenly distributed and the matrix resin phase, and has a fatal defect as a practical material. Moreover, although the thermal conductivity is improved as compared with a general method, it does not reach a practical required level.

Furthermore, the problem of heat dissipation of electronic devices and electronic parts has become extremely serious due to the recent increase in device integration, the increase in heat generation density associated with the downsizing and multi-functionalization of products. In particular, in mobile information terminals that have made remarkable progress, it has become a problem that heat that can cause low-temperature burns is generated from the element when touched. Therefore, there is a demand for a specific material that is unprecedented and that can control the direction of heat conduction and the amount of movement of the material itself and can safely radiate heat. In other words, in the future, materials applied to electronic devices and electronic parts will need new materials with high thermal conductivity as well as existing resin, ceramics, or metal-specific properties. In addition to practicality such as molding processability, light weight, and low cost, which are characteristics of a resin, there is a demand for a thermally conductive material that can control excellent thermal conductivity and heat directionality.
JP 2003-268070 A JP 2004-256687 A JP 2005-54094 A

  The problem of the present invention is that the thermosetting resin used for molding materials for electronic parts, printed boards, and exterior materials for small electronic devices has inherent moldability, lightness, mechanical strength, heat resistance, etc. A heat conductive resin material having an excellent thermal conductivity and an anisotropic thermal conductivity capable of controlling the direction and amount of movement of heat without deteriorating practical properties, and a molded body thereof. It is to provide.

  The present inventors pay attention to the fact that the morphology of a resin material containing a resin and a filler strongly influences thermal conductivity, and heat conductive fillers, particularly fibrous fillers, thermosetting resins, and various additives. The melt viscosity, fluidity, and the dispersion state of each component, interaction between surfaces, etc. were analyzed in detail. As a result, the base material thermosetting resin is blended with an incompatible organic compound and a fibrous filler, and two or more fibers are dispersed in each dispersed particle of the organic compound dispersed in the resin component. It has been found that the filler can be dispersed in contact or in the state of being present inside. In the molded product obtained using this, the network structure of the fibrous filler was formed, and the knowledge that it became what has the outstanding heat conductivity was acquired.

  In particular, by blending a fibrous thermal conductive filler having a specific size and an organic compound having a specific molecular structure incompatible with the base thermosetting resin, in a specific range, It was found that the morphology changed greatly and excellent thermal conductivity was obtained. In other words, the blending of the organic compound having the specific molecular structure described above significantly promotes the dispersion of the filler in the molten resin, and at the same time enhances the chemical interaction between the base resin and the filler, making it ideal for high thermal conductivity. We found that a good morphology was formed.

  Although the mechanism of promoting heat conduction according to the present invention is not necessarily clear, the dispersibility of the fibrous filler is improved by adding an incompatible organic compound to the thermosetting resin, and these are incorporated into the resin. It is considered that a structure in which the fillers are in mesh contact with each other is formed, and a network structure of fibrous filler is formed in the molded body, thereby realizing high thermal conductivity. In this case, the low-viscosity incompatible organic compound is a fiber that is finely dispersed, especially when the thermosetting resin of the base material is melted and mixed with it, lowering the melt viscosity of the resin, and inherently easily aggregated. By effectively increasing the dispersibility of the fibrous filler and at the same time having a strong interaction with the filler surface, the binder between the fillers (work like a network knot that partially aggregates multiple fibrous fillers) It is assumed that a network structure of fibrous filler is formed. Such a network structure is specifically formed with a low blending amount by a fibrous filler having a specific fiber length and fiber diameter. In addition, due to the synergistic effect with incompatible organic compounds, fibrous fillers are brought into contact or very close together, reducing heat propagation loss and sufficiently high thermal conductivity with a small amount of filler. can get. For this reason, the filler compounding quantity was reduced and the knowledge that high heat conductivity could be provided to a molded object was obtained, without inhibiting the original characteristic of resin.

  In addition, since the fibrous filler is not unevenly distributed in a specific resin phase, interfacial breakage is unlikely to occur, and strength reduction does not occur. Further, the decrease in the melt viscosity of the resin component due to the incompatible organic compound described above makes it easier for the fibrous filler to be oriented with respect to the flow direction and the molding surface direction of the resin component, resulting in anisotropic thermal conductivity. It will be obtained. In general, the orientation of the filler in the resin is known to cause a decrease in mechanical strength and warpage. However, the amount of fibrous filler blended is extremely small compared to the conventional method. It was found that these problems can be effectively suppressed in combination with the network structure of the fibrous filler.

  The thermal conductivity of the thermally conductive resin material often depends on the type and amount of filler to be added since the thermal conductivity of the filler to be added varies by one to two digits depending on the type. Depending on the required level of thermal conductivity, the thermal conductivity of the resin can be controlled by changing the type and blending ratio of the filler, but when similar fillers are mixed at the same blending ratio using existing methods In particular, it was confirmed that the thermal conductivity can be remarkably improved by controlling the morphology, and at the same time, the directionality of the thermal conduction and the amount of movement can be controlled. Based on this knowledge, the present invention has been completed.

That is, this invention is a heat conductive resin material containing the resin component which uses a thermosetting resin (A) as a base material, an incompatible organic compound (B), and a fibrous filler (C). In the resin component, the organic compound (B) is present as dispersed particles, and two or more fibrous fillers (C) are in contact with the surface of each dispersed particle, or are present in the dispersed particles, and 500 or more. It has an aspect ratio of 50000 or less, and the organic compound (B) includes one or more selected from ester compounds, olefin compounds, carbonate compounds and amide compounds, and has a melting point of 80 to 200 ° C. It relates to a thermally conductive resin material.

Moreover, this invention relates to the heat conductive molded object shape | molded by injection molding or compression molding using the said heat conductive resin material.

  The heat conductive resin material of the present invention is a mold material for electronic parts, a printed circuit board, and a thermosetting resin material used for an exterior material of a small electronic device. It has an excellent thermal conductivity without deteriorating practical properties such as heat resistance, and has an anisotropic thermal conductivity capable of controlling the direction of the heat conduction and the amount of movement. The thermally conductive molded body of the present invention has excellent thermal conductivity without deteriorating practical properties such as the original moldability, lightness, mechanical strength, heat resistance, etc. possessed by the resin used, and It has anisotropic thermal conductivity that enables control of the direction of heat conduction and the amount of movement.

The heat conductive resin material of the present invention includes a resin component having a thermosetting resin (A) as a base material, an organic compound (B) incompatible with the resin component, and a fibrous filler (C). An organic compound (B) is present as dispersed particles in the resin component, and two or more fibrous fillers (C) are in contact with the surface of each dispersed particle or present in the dispersed particles. The organic compound (B) has an aspect ratio of 500 or more and 50000 or less, and the organic compound (B) includes one or more selected from an ester compound, an olefin compound, a carbonate compound and an amide compound, and has a melting point of 80 to 200 ° C. It is characterized by having .

  The thermosetting resin (A) used in the thermally conductive resin material of the present invention is a base material for the resin component, and any thermosetting resin used in the molding field can be applied. it can. Examples of the thermosetting resin (A) include unsaturated polyester resins, epoxy resins, acrylic resins, phenol resins, melamine resins, urea resins, urethane resins, and the like. In particular, epoxy resins are widely used as sealing materials for printed circuit boards and semiconductor packages because of their excellent electrical insulation, mechanical properties, heat resistance, chemical resistance, etc. In these electronic devices It is preferably applied because a large amount of heat is released outside the apparatus. The epoxy resin refers to a compound containing an epoxy group in a molecule, or a resin structure obtained by three-dimensional crosslinking of an epoxy group and a cured product thereof. For example, bisphenol A type epoxy resin, cresol nobarac type epoxy resin, biphenyl type epoxy resin and the like can be mentioned. These can be used alone or in combination of two or more, and are usually used in combination with a curing agent such as amine, phenol, and acid anhydride.

  The resin component containing the thermosetting resin (A) as a base material constitutes a matrix in the thermally conductive resin material of the present invention, and may contain a thermoplastic resin in part. The thermoplastic resin is preferably incompatible with the organic compound (B), and the content in the matrix resin is, for example, 0.5 to 30 parts by mass or less with respect to 100 parts by mass of the thermosetting resin. A range can be mentioned.

  The organic compound (B) used in the heat conductive resin material of the present invention is incompatible with the thermosetting resin (A) and forms dispersed particles in the base material thermosetting resin (A). To do. The term “incompatible” as used herein refers to those in which dispersed particles are formed with a size of 0.1 μm or more with respect to the base thermosetting resin (A) and exhibit optical incompatibility in the visible light region. In the case of dissimilar resins or a mixture of resin and organic compound, it is extremely rare that each resin is completely thermodynamically compatible (becomes one phase at the molecular level), and it appears to be visible and uniform. However, it is generally present in a dispersed state in a microscopic field below submicron. Therefore, “incompatible” or “not completely compatible” includes most different resin mixed systems. In the present invention, the organic compound (B) that is “incompatible with the resin component” means that the organic compound (B) forms dispersed particles having a size of 0.1 μm or more in the resin component, including a partially compatible state. And what can recognize incompatibility at a visible level.

  The average particle diameter of the dispersed particles of the organic compound (B) is preferably in the range of 0.1 to 500 μm. If the average particle diameter of the dispersed particles of the organic compound (B) is 0.1 μm or more, incompatibility with the resin component can be recognized at a visible level, and the fibrous filler (C) described later is contained in the resin component. In order to improve the thermal conductivity, it is dispersed so as to contact each other in the form of a network, and a fibrous filler (C) and a network structure are formed in the obtained molded body. On the other hand, when the average particle diameter of the dispersed particles is 500 μm or less, aggregation in the resin fraction can be suppressed, and interface breakage due to macrophase separation can be suppressed.

  Here, the average particle diameter can be a value measured by a microscopic method.

  The organic compound (B) that is incompatible with the resin component and has such an average particle diameter is formed by the interaction with the fibrous filler (C) and the surface of a part of the dispersed particles of each organic compound (B). The state which contacted one or more fibrous fillers (C), or the state where two or more fibrous fillers (C) existed in a part inside each organic compound (B) is formed. As shown in the schematic diagram of FIG. 1, the dispersed particles 2 of the organic compound dispersed in the matrix resin 3 serve as a binder for the fibrous filler 1, and the network structure in which the fibrous filler 1 is connected in a mesh shape, It is formed in the matrix resin 3. When the average particle diameter of the dispersed particles of the organic compound (B) is ½ or less of the average fiber length of the fibrous filler, the fibrous filler (C) aggregates in the dispersed particles of the organic compound (B). And the formation of a network structure of the fibrous filler (C) and the dispersed particles of the organic compound (B) can be promoted. For this reason, the network structure by the fibrous filler (C) and the organic compound (B) is easily formed in the matrix resin, and sufficiently high thermal conductivity can be obtained by a small amount of the fibrous filler (C). . Bonding between the organic compound (B) forming the network structure and the fibrous filler (C) includes physical adsorption, electrostatic adsorption, hydrophobic interaction, magnetic adsorption, in addition to chemical bonds such as hydrogen bonds and coordination bonds. It may be due to any action such as geometric factors, and the joining state thereof is either in a state where the fibrous filler (C) penetrates the dispersed particles of the organic compound (B) or in a contact state. There may be.

  The organic compound (B) preferably has a melt viscosity lower than that of the matrix resin component and a melting point lower than that of the matrix resin component. By using such an organic compound (B), the melt viscosity is lowered in mixing with the matrix resin, the fluidity is improved, and the solid fibrous filler can be easily dispersed.

  The organic compound (B) has a polarity or solubility parameter (hereinafter referred to as SP value) equal to or less than that of the matrix resin, and the difference is within 30% of the SP value of the matrix resin. It is preferable. Fibrous fillers (C) such as carbon fibers and nitrides with high thermal conductivity often have a hydrophobic structure that is chemically inert on the surface, and have an organic polarity or SP value equal to or lower than that of the matrix resin. By having a stronger hydrophobic interaction with the compound (B), aggregation of the fibrous filler (C) can be suppressed. Furthermore, since the dispersed particles of the organic compound (B) having an SP value in the above range are finely dispersed with the fibrous filler (C) in the matrix resin, the dispersibility of the fibrous filler (C) is further improved. The fibrous filler (C) can be dispersed in a state where the network structure can be formed. The organic compound (B) includes an organic compound having an SP value equivalent to that of the matrix resin, but these are limited to those incompatible with the matrix resin. In general, an organic compound is often compatible with a matrix resin having the same SP value, but may be incompatible due to the influence of molecular weight, steric structure, and the like. Accordingly, even if the organic compound has an SP value equivalent to that of the matrix resin, those compatible with the matrix resin are not included in the organic compound (B). When the organic compound (B) has an SP value within 30% of the SP value of the matrix resin, the macrophase separation of the organic compound (B) in the matrix resin is suppressed, A network structure is effectively formed.

Here, several theoretical calculation methods are known for the SP value, but from a qualitative point of view, a value obtained by using a group group contribution method (the group contribution method) that is used for general purposes is used. Can be adopted. Specifically, it can be calculated using Equation (1). About each physical property value required for calculation, it is described in literature values (for example, DW Van Krevelen and PJ Hoftyzer, PROPERTY OF POLYMERS: THEIR ESTIMATION AND CORRELATION WITH CHEMICAL STRUCTURE, E19. Alternatively, any experimental value may be used.
δ = (ΣEcohi / ΣVmi) ^1/2 (1)
δ: solubility parameter (SP value)
Ecohi: molar cohesive energy EVmi of each atom group: The molar volume of the organic compound in the atomic group (B), ester compounds, olefinic compounds, carbonate compounds, amide compounds, 80 ° C. melting point selected from our and these mixtures it is those of ~200 ℃. A low molecular weight compound having a molecular weight of 2000 or less is preferable. Such a low molecular weight organic compound has a low melt viscosity and is easily finely dispersed in a matrix resin. In addition to a highly brittle thermosetting resin (A) such as an epoxy resin, a plasticizer or a lubricant or Since it acts as a processing aid such as a mold release agent, there is an advantage that mechanical properties and molding processability are greatly improved in the molded body. Furthermore, it is preferable that the melting point is 80 ° C. or higher because it can suppress softening and elution due to heat for electronic device parts and housings that generate heat. On the other hand, if the melting point is 200 ° C. or less, molding at a high temperature can be avoided, and gas generation and discoloration due to thermal decomposition can be suppressed.

  Among these, aliphatic carboxylic acid amides, aromatic carboxylic acid amides, and aliphatic carboxylic acid esters having a main chain of molecular structure having 8 to 44 carbon atoms and a molecular weight of 200 to 1500, more preferably 300 to 1000. A preferable example is a crystalline organic compound selected from aromatic carboxylic acid esters and the like. These can be used alone or in combination of two or more. Many of these crystalline organic compounds having a specific carbon number and molecular weight can be synthesized from natural fats and oils such as vegetable oils and animal fats, and are easy to handle and can be obtained at low cost. There are many cases. Moreover, when the thermosetting resin (A) is a crystalline resin, it acts as a crystal nucleating agent, and the effect of greatly shortening the molding cycle can be obtained. The aliphatic carboxylic acid amide, aromatic carboxylic acid amide, aliphatic carboxylic acid ester, and aromatic carboxylic acid ester preferably have one or more polar groups introduced into the molecule. Examples of such polar groups include oxygen-containing groups such as hydroxyl groups, carboxyl groups, and glycidyl groups, nitrogen-containing groups such as amino groups, nitro groups, cyano groups, and isocyanate groups, and fluorine-containing groups. In the above compound in which these polar groups are partially introduced, the physicochemical action such as hydrogen bonding is exerted on the thermosetting resin (A) while interacting with the fibrous filler (C). In addition, a binder effect that reinforces the interaction between both the base material thermosetting resin (A) and the fibrous filler (C) is exhibited, and the mechanical strength of the molded body is improved.

  Specific examples of the organic compound (B) include lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, N- Oleyl stearic acid amide, N-stearyl oleic acid amide, N-stearyl stearic acid amide, N-stearyl erucic acid amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid amide, ethylene bis oleic acid amide, Carboxylic acid amides such as ethylene bisstearic acid amide, ethylene biserucic acid amide, ethylene bisisostearic acid amide, butylene bisstearic acid amide, p-xylylene bisstearic acid amide, and polar groups in some of these molecules Introduced compounds, lauric acid ester, palmitic acid ester, oleic acid ester, stearic acid ester, erucic acid ester, N-oleyl palmitic acid ester, N-oleyl oleic acid ester, N-oleyl stearic acid ester, N- Stearyl oleate, N-stearyl stearate, N-stearyl erucate, methylene bis stearate, ethylene bis laurate, ethylene bis caprate, ethylene bis oleate, ethylene bis stearate, ethylene Carboxylic acid esters such as bis erucic acid ester, ethylene bis isostearic acid ester, butylene bis stearic acid ester, p-xylylene bis stearic acid ester and And the like compounds polar group is introduced in part of the al molecule.

  Among the organic compounds (B), a particularly preferable one is a carboxylic acid amide compound derived from castor oil. Specific examples include ricinoleic acid amide, stearic acid amide, oleic acid amide, palmitic acid amide, linoleic acid amide, linolenic acid amide, arachidic acid amide, and derivatives thereof. In addition to extremely excellent thermal conductivity, these are derived from biomass, so they are environmentally compatible, safe, productive, cost-effective, biocompatible, and are hardly soluble in solvents such as alcohol. It has excellent characteristics in practical use.

  It is preferable that content in the heat conductive resin material of the said organic compound (B) is 0.5-20 mass%, More preferably, it is 1-15 mass%. When the content of the organic compound (B) is 0.5% by mass or more, the melt viscosity of the heat conductive resin material can be sufficiently lowered, and the fibrous filler (C) can be sufficiently dispersed. . On the other hand, if the content of the organic compound (B) is 20% by mass or less, the re-aggregation of the finely dispersed organic compound (B) can be suppressed, and the decrease in mechanical strength due to macrophase separation can be suppressed. It can suppress that the organic compound (B) which aggregated in the obtained molded object is exposed to the surface, and can suppress the appearance defect and the poor coating.

  The fibrous filler (C) used for the thermally conductive resin material of the present invention may be fibrous. In general, the thermal conductivity itself of the thermally conductive resin material often depends on the thermal conductivity and addition amount inherent to the fibrous filler (C), and the required degree of thermal conductivity, the thermosetting resin ( The material of the fibrous filler (C) can be appropriately selected according to the type of A) or the organic compound (B). The material of the fibrous filler (C) is preferably an inorganic material having a thermal conductivity of 50 W / m · K or more, such as carbon, nitride, carbide, boride, or metal. When the thermal conductivity of the fibrous filler is 50 W / m · K or more, a molded article having high thermal conductivity can be obtained. Specific examples of these inorganic substances include carbon fibers, boron nitride, aluminum nitride, silicon nitride, silicon carbide, and metal whiskers. Such fibrous fillers have particularly excellent thermal conductivity in the fiber axis direction, and anisotropic thermal conductivity is obtained by orienting in the flow direction of the resin by injection molding or the like. It is possible to control the direction of conduction and the amount of movement. Among the above materials, carbon fiber is excellent in practical use because it has a lower density than other fillers, has a higher thermal conductivity in the direction of the fiber axis than metal, and has almost no adverse environmental impact. There is an advantage. More specifically, the thermal conductivity of the resin can be improved with a very small amount of addition, it has excellent practical properties such as lightness, workability and mechanical strength, is relatively inexpensive, and is easy to handle.

  Here, the measured value by measuring methods, such as a laser flash method, a flat plate heat flow meter method, a temperature wave thermal analysis method (TWA method), a temperature gradient method (flat plate comparison method), can be employ | adopted for thermal conductivity.

  The carbon fiber can be synthesized by any raw material or synthesis method such as PAN, pitch, arc discharge, laser evaporation, CVD (chemical vapor deposition), CCVD (catalytic chemical vapor deposition), etc. Can be used. Among these, carbon fibers obtained by performing a pitch system, a gas phase method, and further graphitizing are preferable because they have excellent crystallinity and excellent thermal conductivity in the fiber axis direction. In particular, carbon (nano) tubes, carbon (nano) horns, and carbon fibers produced in the mesophase pitch system and in the gas phase have a graphite structure that is anisotropic with respect to the fiber axis direction. And higher thermal conductivity can be imparted to the matrix resin.

  As said fibrous filler (C), an average fiber length of 0.5 mm or more and 50 mm or less is preferable. The fibrous filler (C) having such an average fiber length forms the above-described filler network structure very easily even in a low blending ratio, and the fibrous fillers (C) are in contact with each other or very close to each other. Thus, the propagation loss of thermal energy is remarkably reduced, and it has an extremely important and essential function for thermal conductivity. In addition, since the fibrous filler (C) is easily oriented in the flow direction and the surface direction of the resin during molding, both the thermal conductivity and the anisotropic thermal conductivity are improved in the resulting molded body compared to the conventional one. Can be made. This is because the fibrous filler (C) is in contact with or in a very close state in the molded body, so that the contact area between the fibrous fillers (C) or the fibrous filler involved in the heat conduction is present. This is because the effective area of (C) is increased and the thermal resistance is greatly reduced. This is a point that is greatly different from a conventional resin molded body blended with a simple fibrous filler, resulting in an overwhelming difference in thermal conductivity. The average fiber length of the fibrous filler (C) is not less than 0.5 times the thickness of the molded product, and tends to form a plane orientation, that is, a network structure close to two dimensions. Therefore, it is preferable. The thickness of a molded body such as a component or housing of an electronic device is as thin as about 1 mm. From this point, the fibrous filler (C) preferably has a fiber length of 0.5 mm or more. On the other hand, if the average fiber length of the fibrous filler (C) is 50 mm or less, the entanglement between the fibrous fillers (C) suppresses difficulty in mixing and molding with the resin, and during injection molding. Nozzle clogging can be suppressed, which is practically preferable.

  The fibrous filler (C) preferably contains a fibrous filler (D) having a fiber length shorter than the average fiber length. Preferred examples of the fibrous filler (D) having a short fiber length include carbon fibers and aggregates thereof. Examples of the average fiber length of the fibrous filler (D) include 5 nm or more and 50 μm or less. By using such a fibrous filler (D) in combination, antistatic properties and electromagnetic wave shielding properties can be further improved. This is because the fibrous filler (D) improves the conductivity of the resin by including short fiber length fibrous fillers present in a random state with respect to the long fiber length fibrous fillers to be oriented, It becomes possible to highly control the thermal conductivity and the like of the obtained molded body. The content of the fibrous filler (D) having such a short fiber length can be 0.5 to 20% by mass in the matrix resin.

  As the fibrous filler (C), those having an average diameter of more than 1 μm and 200 μm or less are preferably used. When the average diameter of the fibrous filler (C) is larger than 1 μm, there is little tendency to aggregate, and dispersion becomes easy in mixing with the resin. In addition, it is possible to suppress a decrease in workability due to floating or the like due to a low bulk density. On the other hand, if the average diameter is 200 μm or less, it can be uniformly dispersed in the resin, and the occurrence of poor appearance due to exposure of the aggregates of the fibrous filler (C) to the surface of the molded body can be suppressed. it can. The average diameter of such a fibrous filler (C) can be determined by microscopy.

As the fibrous filler (C), those having an aspect ratio of 500 to 50,000. As described above, the average fiber length of the fibrous filler (C) is preferably 0.5 mm or more and 50 mm or less, and the average diameter is preferably greater than 1 μm and 100 μm or less, and is a ratio of these average fiber length and average diameter. An aspect ratio of 500 to 50000 can be obtained.

  The fibrous filler (C) is preferably crystalline. In a conductive material such as metal, the thermal conductivity depends on the mobility of conduction electrons, whereas in ceramics and carbon, lattice vibration contributes greatly to the thermal conductivity. For this reason, in particular, in the fibrous filler (C) made of ceramics, carbon, or the like, a highly crystalline one has better thermal conductivity. Examples of the method for increasing the crystallinity in the ceramic or carbon fibrous filler (C) include a heat treatment at a temperature of 500 to 3000 ° C. in a non-oxidizing atmosphere. In the case where the fibrous filler is formed by a gas phase method at a high temperature, it is often highly crystallized, which is preferable.

  The fibrous filler (C) can be used after surface treatment, if necessary. Specifically, as the surface treatment, oxidation treatment, nitridation treatment, nitration, sulfonation, treatment for introducing a functional group to the surface by these treatments, or addition of a metal, metal compound, organic to the introduced functional group. A treatment for attaching or bonding a compound or the like, a treatment for attaching or bonding a metal, a metal compound, an organic compound, or the like to the surface of the fibrous filler (C) can be exemplified. Specific examples of the functional group include an oxygen-containing group such as a hydroxyl group, a carboxyl group, a carbonyl group, a nitro group, and an amino group, and a nitrogen-containing group. In the fibrous filler (C) in which such a functional group or compound is introduced on the surface, the chemical interaction with the thermosetting resin (A) is enhanced, so that the obtained molded body has a mechanical strength. improves.

  Examples of the surface treatment for the fibrous filler (C) include a treatment for bonding or attaching a functional group or compound having an interaction with the organic compound (B) to the surface. The fibrous filler (C) subjected to such a surface treatment has a stronger bond with the organic compound (B), and can further improve the thermal conductivity in the molded body. Specifically, when the fibrous filler (C) is a carbon fiber, surface treatment with various carboxylic acids can be exemplified.

  Furthermore, the hydrophobic treatment of the surface of the fibrous filler (C) can be mentioned as the surface treatment. Examples of the hydrophobic treatment include a method of performing a heat treatment in an inert gas atmosphere, a fluorination treatment, and the like. Such a fibrous filler (C) subjected to the hydrophobization treatment has a stronger interaction with a resin having a low polarity.

  Although the said surface treatment can also be performed with respect to the whole quantity of a fibrous filler (C), it can also be performed with respect to some fibrous fillers (C).

  It is preferable that content in the heat conductive resin material of the said fibrous filler (C) is 1-40 mass%, More preferably, it is 5-20 mass%. When the content is 1% by mass or more, sufficient thermal conductivity can be obtained in the molded body. On the other hand, if it is 40 mass% or less, especially in the heat conductive resin material containing the low density fibrous filler (C), the increase in the volume fraction is suppressed, and the heat conductive resin material due to the entanglement of the fillers. An increase in melt viscosity of the resin can be suppressed, and excellent moldability can be obtained.

  Various additives can be blended in the heat conductive resin material of the present invention as required. Examples of additives include reinforcing agents, flame retardants, foaming agents, deterioration inhibitors, crystal nucleating agents, colorants, antioxidants, heat resistance improvers, light resistance agents, processing stabilizers, antibacterial agents, fungicides, A plasticizer etc. can be mentioned. Specifically, fillers such as mica and talc, organic fibers such as aramid and polyarylate, glass fibers, and plant fibers such as kenaf can be used as the reinforcing agent. Specific examples of flame retardants include metal hydroxides such as aluminum hydroxide and magnesium hydroxide, nitrogen flame retardants such as melamine and isocyanuric acid compounds, and phosphorus flame retardants such as phosphoric acid compounds. be able to. In addition, various inorganic or organic crystal nucleating agents, coloring agents such as titanium oxide, stabilizers such as radical trapping agents, antioxidants and hydrolysis inhibitors, and antibacterial agents such as silver ions are appropriately blended. Can do.

  The method for producing the heat conductive resin material of the present invention may be a method of mixing the above-mentioned various components. In addition to mixing by hand mixing, a known mixer such as a tumbler mixer, a ribbon blender, a single screw or A melt mixing method using a multi-screw mixing extruder, a roll, or the like can be used. Among these, a method using a relatively weak mixing force such as a tumbler mixer, a ribbon blender, a single screw extruder, etc. can suppress the breakage and pulverization of the fibrous filler (C) in the mixing step, The high thermal conductivity in the fiber axis direction of the fibrous filler (C) tends to be reflected. In addition, when adding a plurality of additives, it is possible to add additives other than the fibrous filler (C) to the resin component in advance, and then add the fibrous filler (C). It is effective because the mixing time of (C) can be shortened, and these breaks and crushing can be reduced. Moreover, in order to ensure sufficient fluidity at the time of melt mixing, it is preferable to set apparatus conditions such as clearance adjustment in the cylinder of the mixer, rotation speed of the screw and stirring blade, and melting temperature conditions.

  The thermally conductive molded body of the present invention is characterized by being molded using the above-described thermally conductive resin material. As a method for molding the thermally conductive molded body, a method used for molding a molded body of a thermosetting resin, such as injection molding, injection compression molding, or compression molding, can be applied. It is preferable that the temperature at the time of melt mixing and molding is not less than the melting point of the resin component and the range in which each component does not deteriorate.

  The thermally conductive molded body of the present invention can be laminated with a coating having different thermal conductivity on the upper or lower part thereof. In order to form a film, a resin with different filler concentration, addition amount, orientation direction, etc., a resin with different compounding ingredients, a resin with different types, etc. are used as raw materials, and these are laminated as a coating film on the surface by coating or the like. What is necessary is just to shape | mold and adhere to a thin film. A thermally conductive molded body having such a laminated structure or a film made of a thin film can also control the directionality of the thermal conductivity three-dimensionally. A thermally conductive molded body having a resin film with low thermal conductivity can suppress the state in which heat is directly transmitted from the heat source to the surface, and is particularly effective from the viewpoint of preventing low-temperature burns on the housing of electronic equipment. .

  Moreover, as a heat conductive molded object of this invention, you may provide the film which consists of the material excellent in the thermal radiation effect | action on the surface. By having a film made of a material excellent in heat radiation action, heat dissipation characteristics can be improved. Molding of a film using a material having an excellent heat radiation effect can be performed by a method of laminating a film as a coating film on the surface by coating or the like, and molding and bonding these into a thin film. Moreover, as a heat conductive molded object of this invention, you may provide the film which consists of a material from which heat capacity differs in the surface. By having a coating made of a material with different heat capacities, the temperature change on the surface can be made dull, which is effective in equipment that directly touches the human body or living organisms or precision equipment that dislikes heat changes. Molding of a film made of materials having different heat capacities can be performed by a method of laminating as a coating film on the surface by coating or the like, or molding and bonding them into a thin film.

  Hereinafter, the heat conductive resin material and the molded body of the present invention will be described in detail, but the technical scope of the present invention is not limited thereto.

[Example 1]
[Preparation of thermally conductive molded body]
For 100 parts by mass of a resin component of 83.3 parts by mass of a bisphenol A type epoxy resin (Epicoat 828, made by oiled shell epoxy) and 16.7 parts by mass of an amine curing agent (Epicure T, made by oiled shell epoxy), As an incompatible organic compound, 10 parts by mass of ethylenebisstearylamide and 5 parts by mass of carbon fiber (mesophase pitch system, length 5 mm, diameter 10 μm, aspect ratio 500) are added, and after stirring well with a batch stirrer, vacuum Defoamed, poured into a Teflon mold to a thickness of 2 mm and cured at room temperature for 4 days. Then, it took out from the type | mold and cut out the molded object of 20x70x2 mm, and it was set as the test piece for thermal conductivity evaluation.

  About the obtained test piece, thermal conductivity was evaluated from in-plane thermal conductivity and anisotropic thermal conductivity.

[Thermal conductivity evaluation]
[In-plane thermal conductivity]
The test piece was fixed to a support, and steady heat was applied to a part of the test piece with a rubber heater preheated to 80 ° C. Observation of heat diffusing from the contact area with the rubber heater to the entire specimen was observed with an infrared thermotracer (manufactured by NEC Sanei, Thermoscanner TS5304), and the thermal conductivity was evaluated by thermographic analysis shown in FIG. did. During the observation, a black body paint having a known emissivity was applied to the surface of the test piece. The ratio, a / b, of the thermal conductivity a of the test piece (sample) shown in FIG. 2A and the thermal conductivity b when only the same fibrous filler shown in FIG. 2B is added, In-plane thermal conductivity was evaluated according to the following criteria. The results are shown in Table 1.

：: a / b is 1.5 or more ○: a / b is 1.1 or more and less than 1.5 Δ: a / b is 0.9 or more and less than 1.1 ×: a / b is less than 0.9.

[Anisotropic thermal conductivity]
A test piece was placed on an aluminum table, a weight previously heated to 80 ° C. was placed thereon, and quantitative heat was applied. The state of heat spreading within a certain time from the installation of the weight was observed with a thermotracer as described above. The thermal diffusion in the direction parallel to the plane was evaluated by comparing the diffusion state of the temperature in the plane of the test piece with the same shape stainless steel plate having isotropic thermal conductivity. Since the heat in the direction perpendicular to the plane moves quickly to the lower aluminum base, the thermal conductivity in the plane direction can be observed remarkably. The thermography which shows the heat | fever diffusion state shows a test piece in Fig.3 (a), and stainless steel in (b). From the thermography, the ratio a / b of the area a in the constant temperature range after a predetermined time of the test piece and the area b in the constant temperature range after a predetermined time of the stainless steel, a / b, is obtained. The diffusion and anisotropic thermal conductivity were evaluated. The results are shown in Table 1.

○: a / b is 1.5 or more Δ: a / b is 1.1 or more and less than 1.5 ×: a / b is less than 1.1

[ Reference Example 2]
Tested in the same manner as in Example 1, except that the mesophase pitch system, length 2 mm, diameter 10 μm, and aspect ratio 200 was used as the carbon fiber instead of the mesophase pitch system, length 5 mm, diameter 10 μm, and aspect ratio 500. A piece was prepared, and thermal conductivity was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[ Reference Example 3]
Cresol novolac type epoxy resin (EOCN1020, Nippon Kayaku) 64.7 parts by mass, phenol resin curing agent (HF45, manufactured by Meiwa Kasei) 34.6 parts by mass, curing accelerator (triphenylphosphine, Kanto Chemical) 0 10 parts by mass of ethylenebisoleylamide as an incompatible organic compound and 5 carbon fibers (mesophase pitch system, length 2 mm, diameter 20 μm, aspect ratio 100) per 100 parts by mass of the resin component of 0.7 parts by mass After adding a mass part, it mixed with the 120 degreeC extruder for about 20 second, Then, it cooled and grind | pulverized. Thereafter, the pulverized product was put in a Teflon mold so that the thickness was 2 mm, and compression molded with a 170 ° C. press. Thereafter, the molded body of 20 × 70 × 2 mm was taken out from the mold and cut into a test piece for thermal conductivity evaluation. About the obtained test piece, it carried out similarly to Example 1, and evaluated thermal conductivity. The results are shown in Table 1.

[Example 4]
Tested in the same manner as in Example 1 except that a mesophase pitch system, length 5 mm, diameter 10 μm, aspect ratio 500 was used as the carbon fiber, and a gas phase system, length 10 mm, diameter 20 μm, aspect ratio 500 was used. A piece was prepared, and thermal conductivity was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A test piece was prepared in the same manner as in Example 1 except that ethylene bisstearylamide was not used as the incompatible organic compound, and the thermal conductivity was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
A test piece was prepared in the same manner as in Reference Example 3 except that ethylenebisoleylamide was not used as the incompatible organic compound, and the thermal conductivity was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
A test piece was prepared in the same manner as in Example 1 except that compatible polydimethylsiloxane (average molecular weight 2000) was used in place of the incompatible organic compound ethylenebisoleylamide. Thus, thermal conductivity was evaluated. The results are shown in Table 1.

  From the results, the thermally conductive molded bodies of Examples 1 to 4 to which the incompatible organic compound and the fibrous filler were added all showed high thermal conductivity. In particular, in Example 1 in which a carbon filler having a fiber length of 5 mm was added and in Example 4 in which a long fiber carbon fiber having a fiber length of 10 mm was added, a significant improvement in in-plane thermal conductivity was observed.

  The heat conductive molded body obtained from the heat conductive resin material of the present invention can be applied to casings and parts of devices that generate heat such as electronic devices, home appliances, battery materials, thermal energy conversion materials, automobile parts, aircraft It can be widely applied to fields that require high thermal conductivity such as parts, railway parts, and space.

It is a schematic diagram which shows the structure of the heat conductive resin material of this invention. It is a figure which shows the thermography which shows in-plane thermal conductivity of an example of the heat conductive molded object of this invention in a comparison with a prior art example. It is a figure which shows a thermography in comparison with the stainless steel which shows the anisotropic heat conductivity of an example of the heat conductive molded object of this invention which shows isotropic heat conductivity.

Explanation of symbols

1 Fibrous filler (C)
2 Dispersed particles of organic compound (B) 3 Resin component

Claims (24)

A thermally conductive resin material comprising a resin component having a thermosetting resin (A) as a base material, an organic compound (B) incompatible with the resin component, and a fibrous filler (C), In addition, the organic compound (B) is present as dispersed particles, and two or more fibrous fillers (C) are in contact with the surface of each dispersed particle, or are present in the dispersed particles, and have an aspect ratio of 500 to 50,000. And the organic compound (B) contains one or more selected from ester compounds, olefin compounds, carbonate compounds and amide compounds, and has a melting point of 80 to 200 ° C. material.   The thermally conductive resin material according to claim 1, wherein the fibrous filler (C) is in mesh contact.   The thermally conductive resin material according to claim 1 or 2, wherein the fibrous filler (C) has an average fiber length that is at least twice the average particle diameter of the dispersed particles of the organic compound (B).   The thermally conductive resin material according to any one of claims 1 to 3, wherein the fibrous filler (C) has an average fiber length of 0.5 mm or more and 50 mm or less.   The thermally conductive resin material according to any one of claims 1 to 4, wherein the fibrous filler (C) has an average diameter of more than 1 µm and not more than 100 µm. The thermally conductive resin material according to any one of claims 1 to 5, wherein the fibrous filler (C) is contained in an amount of 1 to 40 mass% based on the total mass . The fibrous filler (C) is composed of an inorganic material having a thermal conductivity of 50 W / m · K or more, including one or more selected from carbon, nitride, carbide, boride and metal. The thermally conductive resin material according to any one of claims 1 to 6. The thermally conductive resin material according to any one of claims 1 to 7, wherein the fibrous filler (C) is made of crystalline carbon fiber . When the fibrous filler (C) is subjected to surface treatment, one or more polar groups selected from oxygen-containing groups, nitrogen-containing groups and sulfur-containing groups are introduced, or the surface of the fibrous filler (C) or The thermally conductive resin material according to any one of claims 1 to 8, wherein one or more selected from metals, metal compounds, and organic compounds are bonded to or attached to the polar group . The thermally conductive resin material according to any one of claims 1 to 9, wherein the fibrous filler (C) includes a fibrous filler (D) having an average fiber length of 0.5 mm or less . The thermally conductive resin material according to claim 10 , wherein the fibrous filler (D) is a carbon fiber having an average fiber length of 5 nm to 50 µm or an aggregate thereof . The thermally conductive resin material according to claim 10 or 11, wherein the fibrous filler (D) is contained in an amount of 0.5 to 20 mass% based on the total mass . The thermally conductive resin material according to any one of claims 1 to 12 , wherein the dispersed particles of the organic compound (B) have an average particle diameter in the range of 0.1 to 500 µm . The heat conductive resin material according to any one of claims 1 to 13 , wherein the organic compound (B) is a low molecular compound having a molecular weight of 2000 or less . The organic compound (B) contains one or more selected from vegetable oils and fats, animal fats and oils, and wax-like substances synthesized from these oils and fats. Thermally conductive resin material. The organic compound (B) has a main chain having 8 to 44 carbon atoms and a molecular weight of 300 to 1000, an aliphatic carboxylic acid amide, an aromatic carboxylic acid amide, an aliphatic carboxylic acid ester, and an aromatic carboxylic acid ester. The thermal conductive resin material according to claim 1 , comprising one or more selected from these compounds having a polar group . Polar group, the thermally conductive resin material according to claim 16, characterized in that it comprises one or more selected from an oxygen-containing group and a nitrogen-containing group. The organic compound (B) is a thermally conductive resin material according to claim 16 or 17, characterized in that it comprises a derivatized carboxylic acid amide compound from castor oil. The organic compound (B) contains ricinoleic acid amide, stearic acid amide, oleic acid amide, palmitic acid amide, linoleic acid amide, linolenic acid amide, arachidic acid amide, or a derivative thereof. thermally conductive resin material according. The thermally conductive resin material according to any one of claims 1 to 19, wherein the organic compound (B) is contained in an amount of 0.5 to 20% by weight based on the total mass . The thermosetting resin material according to any one of claims 1 to 20, wherein the thermosetting resin (A) contains an epoxy resin. A thermally conductive molded article, which is molded by injection molding using the thermally conductive resin material according to any one of claims 1 to 21. A thermally conductive molded article, which is molded by compression molding using the thermally conductive resin material according to any one of claims 1 to 21. 24. The thermally conductive molded article according to claim 22 or 23, wherein the fibrous filler (C) has an average fiber length of 0.5 to 100 times the thickness .

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