JPWO2018181146A1 - Thermal conductive resin composition - Google Patents

Abstract

A heat conductive resin composition having excellent fluidity, toughness, and heat conductivity. The heat conductive resin composition comprises a thermoplastic polyester resin (A), a thermoplastic polyester elastomer (B), and graphite (C). (A) is 30 to 55 parts by mass, (B) is 5 to 20 parts by mass, (C) is 25 to 60 parts by mass ((A) + (B) + (C) = 100 parts by mass), and the thermal conductivity in the surface direction of a molded product obtained from the heat conductive resin composition is 5 W / (m · K) or more, width 10 mm, and thickness. The flow length in a 2 mm shape (measurement conditions: cylinder temperature 280 ° C., mold temperature 140 ° C., pressure 60 MPa) is 200 mm or more.

Description

  The present invention relates to a thermally conductive resin composition having excellent fluidity, toughness, and thermal conductivity.

  With the miniaturization and high integration of electric and electronic devices, the heat generation of mounted components and the high temperature of the use environment have become remarkable, and there has been a growing demand for improved heat radiation of constituent members. In particular, components made of metals and ceramics having high thermal conductivity are currently used for heat radiation of automobile members and high-power LEDs. There is a need for a resin material having thermal conductivity and moldability.

  As a method of imparting thermal conductivity to a resin, a method of adding a high thermal conductive filler such as graphite is disclosed.

  Patent Literature 1 discloses a resin composition having excellent thermal conductivity and fluidity by adding graphite particles having a specific property, particle diameter, and aspect ratio to a resin, but adding a large amount of graphite. For this reason, the decrease in the fluidity is large, and it cannot be said that the fluidity is excellent. In the case of a mold shape in which a large number of molded articles are taken, there is a high possibility that molding becomes extremely difficult.

  As a technique for improving the thermal conductivity, filling a resin with graphite and a nano-sized carbon-based filler has been studied. For example, in Patent Literature 2, a resin composition in which flat graphite and nano-sized carbon nanofibers are dispersed in a thermoplastic elastomer is used to form a string-like strand using a twin-screw extruder, and then this is rolled. A method for continuously obtaining a sheet having a high thermal conductivity by pressing the sheet is described. According to this method, the graphite is oriented by a roll press, and the nanofibers are dispersed between the layers, so that a highly efficient heat conduction path is formed, and a processed product can be obtained continuously while achieving a high heat conductivity. However, there is a problem that the degree of freedom of the shape of the obtained workpiece is extremely limited because it is premised on pressing by a roll.

  On the other hand, in Patent Document 3, the use of flaky graphite and carbon nanofibers or carbon nanotubes prevents the destruction of nanofibers due to shearing during melt mixing by adding a fluororesin, and the graphite is oriented by injection molding after melt kneading. A heat conductive resin composition having a high heat conductivity by dispersing and maintaining nanofibers between surface layers is described. However, the use of extremely expensive carbon nanofibers not only makes the resin composition expensive, but also in this case, graphite must be added in a large amount, so that a decrease in fluidity occurs. No statement was made.

International Publication WO2015 / 190324 pamphlet JP-A-2015-36383 JP-A-2006-204570

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermally conductive resin composition having excellent fluidity, toughness, and thermal conductivity.

  The present inventors have intensively studied to solve the above problems. As a result, it has been found that the above problems can be solved by mixing a thermoplastic elastomer resin with a polyester elastomer and a flaky graphite having a specific shape and an expandable graphite at a specific ratio, thereby completing the present invention. Was. More specifically, the present invention provides the following.

[1] A heat conductive resin composition containing a thermoplastic polyester resin (A), a thermoplastic polyester elastomer (B), and graphite (C), and each content of (A) is 30 to 55 mass%. Parts, (B) is 5 to 20 parts by mass, (C) is 25 to 60 parts by mass ((A) + (B) + (C) = 100 parts by mass), and is obtained from the heat conductive resin composition. The flow length (measurement conditions: cylinder temperature of 280 ° C., mold temperature of 140 ° C., pressure of 60 MPa) in the shape of a molded product having a surface thermal conductivity of 5 W / (m · K) or more, a width of 10 mm and a thickness of 2 mm is measured. A thermally conductive resin composition having a thickness of 200 mm or more.
[2] The graphite (C) is composed of flaky graphite (C-1) having an average particle diameter of 200 to 400 μm and expandable graphite (C-2) having an average particle diameter of 10 to 40 μm, and a mass ratio thereof. Is in the range of flake graphite (C-1) / expandable graphite (C-2) = 100/0 to 78/22, the heat conductive resin composition according to [1].
[3] The heat conductive resin composition according to [1] or [2], wherein the thermoplastic polyester resin (A) is polyethylene terephthalate.
[4] The thermally conductive resin composition according to any one of [1] to [3], further containing a carbodiimide compound (D).
[5] A molded article comprising the thermally conductive resin composition according to any one of [1] to [4].

  According to the present invention, the thermoplastic polyester resin (A) is mixed with the thermoplastic polyester elastomer (B) and the graphite (C) having a specific property and a specific ratio, thereby being excellent in fluidity, toughness, and thermal conductivity. The resulting resin composition can be obtained. In addition, heat shock resistance is excellent due to the development of good toughness.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all, and can be implemented with appropriate modifications within the scope of the present invention. . In addition, although the description may be omitted as appropriate for portions where the description is duplicated, this does not limit the gist of the invention.

  Hereinafter, thermoplastic polyester resin (A), thermoplastic polyester elastomer (B), graphite (C) (flaky graphite (C-1) and expandable graphite (C-2)), carbodiimide compound (D), and others The components and the thermally conductive resin composition will be described in order.

[Thermoplastic polyester resin (A)]
The thermoplastic polyester resin (A) used in the present invention includes an amorphous polyester resin such as an amorphous semi-aromatic polyester and an amorphous wholly aromatic polyester, a crystalline semi-aromatic polyester and a crystalline wholly aromatic polyester. Examples thereof include crystalline polyester resins such as polyester, and random block graft copolymers of these exemplified polymers. These thermoplastic polyester resins can be used alone or in combination of two or more. When two or more resins are used in combination, a compatibilizer or the like may be added as necessary. These thermoplastic polyester resins (A) may be properly used depending on the purpose.

  Among these thermoplastic polyester resins (A), the fact that a part or all of the resin is a thermoplastic resin having crystallinity indicates that the obtained resin composition tends to have a high thermal conductivity, It is preferable because the graphite can be easily contained in the resin. In these crystalline thermoplastic resins, even if the entire resin is crystalline, only a part of the resin is crystalline, such as only a specific block in the molecule of the block or graft copolymer resin. You may. There is no particular limitation on the crystallinity of the resin. Further, as the thermoplastic resin, a polymer alloy of an amorphous resin and a crystalline resin can be used. There is no particular limitation on the crystallinity of the resin.

  Some thermoplastic resins, some or all of which have crystallinity, can be crystallized, but if used alone or molded under the molding processing conditions of characteristics, non- Some resins exhibit crystallinity. When such a resin is used, a part or the whole of the resin can sometimes be crystallized by devising a molding method such as a stretching treatment or a post-crystallization treatment.

  Specific examples of the crystalline polyester include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-1,2-bis ( In addition to phenoxy) ethane-4,4'-dicarboxylate, crystallinity such as polyethylene isophthalate / terephthalate, polybutylene terephthalate / isophthalate, polybutylene terephthalate / decane dicarboxylate and polycyclohexane dimethylene terephthalate / isophthalate Copolymerized polyester and the like can be mentioned. Among these, polyethylene terephthalate is particularly preferred from the viewpoint of heat shock resistance when used as an automobile part.

  The polyethylene terephthalate resin is basically a homopolymer of ethylene terephthalate units. In addition, other components can be copolymerized up to about 5 mol% within a range that does not impair various properties. Examples of the other components include components used for a copolymerized polyester resin described below.

  Copolyester resins include terephthalic acid, isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalenedicarboxylic acid, ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, Polyester resin containing at least one selected from the group consisting of 2,4-butanediol, 1,2-propanediol, 1,3-propanediol, and 2-methyl-1,3-propanediol as a copolymer component. Preferably, there is. Among them, a copolymerized polyester containing 50 mol% or more of terephthalic acid as a dicarboxylic acid component and 50 mol% or more of ethylene glycol as a glycol component is more preferable. As components to be copolymerized, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, aromatic or aliphatic polybasic acids such as trimellitic acid or esters thereof, and the like, as acid components other than terephthalic acid, Examples of glycol components other than ethylene glycol include diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, and 2-methyl- 1,3-propanediol and the like. As components to be copolymerized, isophthalic acid and neopentyl glycol are preferred from the viewpoint of availability and various characteristics.

  As the molecular weight of the polyethylene terephthalate resin, the intrinsic viscosity (0.1 g of a sample was dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6/4) and measured at 30 ° C. using an Ubbelohde viscosity tube; dl / g) ) Is preferably from 0.5 to 1.1 dl / g, more preferably from 0.6 to 1.0 dl / g. If it is less than 0.5 dl / g, the strength of the resin is reduced, and the molded article tends to be brittle. In addition, the intrinsic viscosity can be adjusted by blending polyethylene terephthalate resins having different intrinsic viscosities. For example, a polyethylene terephthalate resin having an intrinsic viscosity of 0.9 dl / g can be prepared by blending a polyethylene terephthalate resin having an intrinsic viscosity of 1.0 dl / g with a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g.

  The content of the thermoplastic polyester resin (A) is 30 to 55 parts by mass, when the total of (A) + (B) + (C) in the heat conductive resin composition is 100 parts by mass, More preferably, it is 35 to 55 parts by mass.

[Thermoplastic polyester elastomer (B)]
The thermoplastic polyester elastomer (B) used in the present invention includes a hard segment composed of a polyester containing an aromatic dicarboxylic acid and an aliphatic and / or alicyclic glycol as components, an aliphatic polyether, and an aliphatic polyester. And a polyester elastomer having at least one soft segment selected from aliphatic polycarbonates.

  In the thermoplastic polyester elastomer (B) used in the present invention, as the aromatic dicarboxylic acid constituting the polyester of the hard segment, an ordinary aromatic dicarboxylic acid is widely used and is not particularly limited, but as a main aromatic dicarboxylic acid, It is preferably terephthalic acid or naphthalenedicarboxylic acid. The naphthalenedicarboxylic acid is preferably 2,6-naphthalenedicarboxylic acid among the existing isomeric structures. Other acid components include diphenyldicarboxylic acid, isophthalic acid, aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, cyclohexanedicarboxylic acid, alicyclic dicarboxylic acids such as tetrahydrophthalic anhydride, succinic acid, glutaric acid, adipine Examples thereof include acids, azelaic acid, sebacic acid, dodecane diacid, dimer acid, and aliphatic dicarboxylic acids such as hydrogenated dimer acid. These are used in a range that does not significantly lower the melting point of the polyester elastomer, and the amount thereof is preferably less than 30 mol% of the total acid component, more preferably less than 20 mol%.

  In the thermoplastic polyester elastomer (B) used in the present invention, general aliphatic or alicyclic glycols are widely used as the aliphatic or alicyclic glycol constituting the hard segment polyester, and are not particularly limited. It is preferable that the alkylene glycol is mainly a C2-8 alkylene glycol. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Among these, it is preferable to use either ethylene glycol or 1,4-butanediol for imparting heat resistance.

  As a component constituting the polyester of the hard segment, a butylene terephthalate unit (a unit composed of terephthalic acid and 1,4-butanediol) or a butylene naphthalate unit (2,6-naphthalenedicarboxylic acid and 1,4-butanediol) Are preferred from the viewpoint of physical properties, moldability and cost performance.

  When an aromatic polyester suitable as a polyester constituting a hard segment in the thermoplastic polyester elastomer (B) used in the present invention is produced in advance and then copolymerized with a soft segment component, the aromatic polyester is usually Can be easily obtained according to the polyester production method. Further, the polyester preferably has a number average molecular weight of 10,000 to 40,000.

The soft segment of the thermoplastic polyester elastomer (B) used in the present invention is at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. Aliphatic polyethers include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, polyoxytrimethylene glycol, copolymers of ethylene oxide and propylene oxide, and ethylene oxide of polyoxyethylene glycol. Adducts, copolymers of ethylene oxide and tetrahydrofuran and the like can be mentioned.
Examples of the aliphatic polyester include poly (ε-caprolactone), polyenantholactone, polycaprylolactone, and polybutylene adipate.

  The thermoplastic polyester elastomer (B) used in the present invention is a copolymer containing terephthalic acid, 1,4-butanediol, and polyoxytetramethylene glycol as main components for reasons of economy, heat resistance, and cold resistance. Preferably, there is. In the dicarboxylic acid component constituting the thermoplastic polyester elastomer (B), terephthalic acid is preferably at least 40 mol%, more preferably at least 70 mol%, even more preferably at least 80 mol%, It is particularly preferred that the content be 90 mol% or more. In the glycol component constituting the thermoplastic polyester elastomer (B), the total of 1,4-butanediol and polyoxytetramethylene glycol is preferably at least 40 mol%, more preferably at least 70 mol%, It is more preferably at least 80 mol%, particularly preferably at least 90 mol%.

  The number average molecular weight of the polyoxytetramethylene glycol is preferably from 500 to 4,000. If the number average molecular weight is less than 500, it may be difficult to exhibit elastomer properties. On the other hand, when the number average molecular weight exceeds 4,000, the compatibility with the polyester portion constituting the hard segment of the thermoplastic polyester elastomer (B) decreases, and it may be difficult to copolymerize in a block shape. The number average molecular weight of the polyoxytetramethylene glycol is more preferably 800 or more and 3000 or less, further preferably 1000 or more and 2500 or less, and particularly preferably 1500 or more and 2500 or less.

  The copolymerization amount of the polyoxytetramethylene glycol is preferably 5 to 20 mol% based on all glycol components constituting the thermoplastic polyester elastomer (B). The content of polyoxytetramethylene glycol is more preferably from 7 mol% to 18 mol%, more preferably from 8 mol% to 15 mol%, based on all glycol components.

  In the thermoplastic polyester elastomer (B) used in the present invention, parts by mass of a crystalline polyester constituting a hard segment and at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates constituting a soft segment. The ratio is preferably in the range of hard segment: soft segment = 30: 70-95: 5, more preferably 40: 60-90: 10, even more preferably 45: 55-87: 13.

  The thermoplastic polyester elastomer (B) used in the present invention is preferably a crystalline polyester having a melting point of 150 ° C. or more and 230 ° C. or less so that it can be distributed at room temperature. The melting point of the thermoplastic polyester elastomer (B) is preferably from 180 to 220 ° C, and particularly preferably from 190 to 210 ° C, in order to satisfy various properties according to the present invention. If the melting point is lower than 150 ° C., it is difficult to satisfy the heat resistance for automobiles and home appliances. If the melting point is higher than 230 ° C., the crystallinity of the polyester elastomer is high and sufficient toughness may not be obtained.

  The reduced viscosity of the thermoplastic polyester elastomer (B) used in the present invention is preferably 0.5 dl / g or more and 3.5 dl / g or less as measured by a measuring method described later. If it is less than 0.5 dl / g, the durability as a resin is low, and if it exceeds 3.5 dl / g, workability such as injection molding may be insufficient. The reduced viscosity of the thermoplastic polyester elastomer (B) is more preferably from 1.0 dl / g to 3.0 dl / g, further preferably from 1.5 dl / g to 2.8 dl / g. The reduced viscosity was measured by dissolving 0.05 g of a sample in 25 ml of a mixed solution (phenol / tetrachloroethane = 60/40 (mass ratio)) and measuring the temperature at 30 ° C. using an Ostwald viscometer. The acid value is preferably 200 eq / t or less, particularly preferably 50 eq / t or less.

  The content of the thermoplastic polyester elastomer (B) is 5 to 20 parts by mass, when the total of (A) + (B) + (C) in the heat conductive resin composition is 100 parts by mass, Preferably it is 10-20 mass parts, More preferably, it is 12-18 mass parts. By blending the thermoplastic polyester elastomer (B) within this range, various properties can be satisfied. Examples of the thermoplastic polyester elastomer (B) that can be used in the present invention include the “Perprene” series manufactured by Toyobo Co., Ltd.

[Graphite (C)]
The graphite (C) blended in the heat conductive resin composition of the present invention is not particularly limited, and various graphites can be used, and either natural graphite or artificially produced graphite is used. May be. For example, scaly graphite, earthy graphite, expandable graphite, artificial graphite, pyrolytic graphite and the like can be mentioned. These graphites may be any of dried, calcined, pulverized and / or classified. The pulverization is not particularly limited, and can be performed using a conventionally known apparatus such as a rod mill, a ball mill, and a jet mill.

  Above all, it is preferable to use flaky graphite and expandable graphite from the viewpoint of thermal conductivity and fluidity, and handling during production. The present inventors have intensively studied the type of graphite and its average particle diameter, and the addition ratio thereof, and have found that there is a combination that can obtain the maximum thermal conductivity with a smaller amount of addition. It was reached. When the ratio between the flaky graphite (C-1) and the expandable graphite (C-2) is in a specific range, and each average particle size is in a specific range, fluidity, thermal conductivity, toughness, A thermally conductive resin composition having a very good balance of various properties such as heat shock resistance can be obtained.

  The flaky graphite (C-1) preferably has an average particle size of 200 to 400 μm, more preferably 200 to 350 μm, and still more preferably 250 to 350 μm. When the average particle size is less than 200 μm, the thermal conductivity of the resin composition decreases or the amount of the resin composition must be increased. In addition, as the particle diameter increases, the thermal conductivity tends to increase. This can be a factor that lowers the thermal conductivity. The average particle diameter is measured by the method described in Examples. Commercially available flaky graphite (C-1) can be used.

  The expandable graphite (C-2) preferably has an average particle size of 10 to 40 μm, more preferably 15 to 30 μm, and still more preferably 20 to 30 μm. Expandable graphite has good thermal conductivity compared to flaky graphite, but those having a large average particle size are deteriorated in handling properties during production, and fluidity, toughness, etc. are markedly reduced, so that it is preferable. Absent. The average particle diameter is measured by the method described in Examples. What is marketed can be used for the expandable graphite (C-2).

  The graphite (C) may be used alone as the flaky graphite (C-1) having the above average particle diameter, but is used in combination with the expandable graphite (C-2) having the above average particle diameter. Is preferred in that the maximum thermal conductivity can be obtained. The mass ratio between the flaky graphite (C-1) having the above average particle diameter and the expandable graphite (C-2) having the above average particle diameter is preferably 100/0 to 78/22, and 90/10 to 90/10. 78/22 is more preferred, and 90/10 to 80/20 is even more preferred. If the amount of the expandable graphite (C-2) is more than 22% by mass of the entire graphite, the fluidity and toughness of the resin composition are significantly reduced as described above, which is not preferable. As the flaky graphite (C-1), the flaky graphite deviating from the above average particle diameter may be contained at 20% by mass or less, more preferably 10% by mass or less, but the flaky graphite deviating from the above average particle diameter may be contained. It is particularly preferred not to contain graphite. The expandable graphite (C-2) may contain an expandable graphite having a size outside the above-mentioned average particle diameter of 20% by mass or less, more preferably 10% by mass or less. It is particularly preferred not to contain graphite.

  The content of graphite (C) is 25 to 60 parts by mass, preferably 30 parts by mass, when the total of components (A) + (B) + (C) in the thermally conductive resin composition is 100 parts by mass. To 50 parts by mass, more preferably 40 to 50 parts by mass. Even when the specific average particle diameter and the specific graphite described above are used in a specific ratio, the thermal conductivity is low when the amount of graphite itself is small, and conversely when the amount exceeds 60 parts by mass, the production time is reduced. Of the resin composition is extremely poor, and the fluidity, toughness and the like of the resin composition are greatly reduced.

[Carbodiimide compound (D)]
The carbodiimide compound (D) in the present invention is not particularly limited as long as it is a compound having a carbodiimide group (-N = C = N-) in the molecule. In the carbodiimide compound (D) used in the present invention, the group bonded to the carbodiimide group is not particularly limited, and may be an aliphatic group, an alicyclic group, an aromatic group, or a group formed by bonding these organic groups (for example, a benzyl group). Phenethyl group, 1,4-xylylene group, etc.). Examples of the carbodiimide compound suitably used in the present invention include an aliphatic carbodiimide compound in which an aliphatic group is connected to a carbodiimide group, an alicyclic carbodiimide compound in which an alicyclic group is connected to a carbodiimide group, and a carbodiimide group. Examples include an aromatic carbodiimide compound in which an aromatic group or a group containing an aromatic group is linked. As the carbodiimide compound (D), one type may be used alone, or two or more types may be used in combination.

  Specific examples of the aliphatic carbodiimide compound include diisopropylcarbodiimide, dioctyldecylcarbodiimide, and the like, and specific examples of the alicyclic carbodiimide compound include dicyclohexylcarbodiimide.

  Specific examples of the aromatic carbodiimide compound include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, N-tolyl-N'-phenylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, -P-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-chlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, p-phenylene -Bis-di-o-tolylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-chlorophenylcarbodiimide, ethylene-bis-diphenylca Mono or dicarbodiimide compounds such as bodimide, poly (4,4′-diphenylmethanecarbodiimide), poly (3,5′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (p-phenylenecarbodiimide) m-phenylenecarbodiimide), poly (naphthylenecarbodiimide), poly (1,3-diisopropylphenylenecarbodiimide), poly (1-methyl-3,5-diisopropylphenylenecarbodiimide), poly (1,3,5-triethyl) Polycarbodiimide compounds such as phenylenecarbodiimide) and poly (triisopropylphenylenecarbodiimide).

  When the carbodiimide compound (D) is a polycarbodiimide compound, the molecular weight is preferably 2000 or more. By using a polycarbodiimide compound having such a molecular weight, generation of gas or odor during melt-kneading or molding can be suppressed.

  Among these carbodiimide compounds (D), 4.4‘-dicyclohexylmethane diisocyanate is more preferred from the viewpoint of the stability of the carbodiimide group in a moist heat environment and the effect of improving hydrolysis resistance.

  In the present invention, the use (content) of the carbodiimide compound (D) is not particularly limited as long as the object of the present invention is not hindered. The carbodiimide compound (D) may not be used. The use (content) of the carbodiimide compound (D) is 0.05 to the total of (A) + (B) + (C) 100 parts by mass as long as the fluidity of the thermally conductive resin composition is not impaired. It is preferably in the range of 0.2 to 0.2 parts by mass. The carbodiimide compound (D) reacts with the thermoplastic polyester resin (A) and the thermoplastic polyester elastomer (B) to block the end thereof, improve hydrolysis resistance, and react with oligomers and the like during molding. It is thought that it plays a role in reducing gas generation by that, but if it is less than 0.05 parts by mass, it is difficult to obtain the desired characteristics, and if it is more than 0.2 parts by mass, it will end. This tends to increase the viscosity at the same time as the reaction, resulting in a decrease in fluidity.

[Other ingredients]
The heat conductive resin composition of the present invention may contain a heat conductive filler other than (C) together with the thermoplastic polyester resin (A), the thermoplastic polyester elastomer (B) and the graphite (C) as long as the effect is not impaired. , A filler other than the thermally conductive filler, and a resin other than (A) and (B). The shape of the thermally conductive filler and filler other than (C) is not particularly limited, and may be, for example, flaky, fibrous, flake, plate, spherical, particulate, fine particle, nanoparticle, aggregated particle, Examples include various shapes such as a tube shape, a nanotube shape, a wire shape, a rod shape, an irregular shape, a rugby ball shape, a hexahedral shape, a composite particle shape in which large particles and fine particles are compounded, and a liquid. Specific examples of the thermally conductive filler other than (C) include metal fillers such as aluminum and nickel, low melting point alloys having a liquidus temperature of 300 ° C. or more and a solidus temperature of 150 ° C. or more and 250 ° C. or less, and oxides. Metal oxides such as aluminum, magnesium oxide, silicon oxide, beryllium oxide, copper oxide and cuprous oxide; metal nitrides such as aluminum nitride and silicon nitride; metal carbides such as silicon carbide; metal carbonates such as magnesium carbonate; diamond Insulating carbon materials such as aluminum hydroxide, magnesium hydroxide and other metal hydroxides, alumina, boron nitride, glass fibers, carbon fibers, potassium titanate whiskers, silicon nitride fibers, carbon nanotubes, talc, wollastonite And one or more of these can be used. The amount added is not particularly limited, but as the amount added increases, the thermal conductivity can be improved. The heat conductive filler other than the above (C) may be a natural product or a synthesized product. In the case of a natural product, there is no particular limitation on the place of production and the like, which can be appropriately selected.

  In the heat conductive resin composition of the present invention, known fillers can be widely used according to the purpose other than the above heat conductive filler. Examples of the filler other than the thermally conductive filler include diatomaceous earth powder, basic magnesium silicate, calcined clay, fine powder silica, quartz powder, crystalline silica, kaolin, antimony trioxide, fine powder mica, molybdenum disulfide, and rock. Inorganic fibers such as wool, ceramic fibers, and asbestos, and glass fillers such as glass fibers, glass powder, glass cloth, and fused silica are exemplified. By using these fillers, it becomes possible to improve, for example, favorable properties in application of the resin composition, such as thermal conductivity, mechanical strength, and abrasion resistance. Further, if necessary, organic fillers such as paper, pulp, wood, synthetic fibers such as polyamide fibers, aramid fibers, and boron fibers, and resin powders such as polyolefin powders can be used in combination.

  The heat-conductive filler and the filler other than the heat-conductive filler used in the present invention enhance the adhesiveness of the interface between the resin and the filler or facilitate the workability. Surface treatment may be performed with various surface treatment agents such as monomers. The surface treatment agent is not particularly limited, and conventionally known agents such as a silane coupling agent and a titanate coupling agent can be used. Among them, epoxy group-containing silane coupling agents such as epoxy silane, amino group-containing silane coupling agents such as amino silane, and polyoxyethylene silane are preferable because they hardly lower the physical properties of the resin. The surface treatment method of the filler is not particularly limited, and a usual treatment method can be used.

  The heat conductive resin composition of the present invention further comprises an antioxidant, a heat stabilizer, an ultraviolet absorber, an antistatic agent, a dye, a pigment, a lubricant, a plasticizer, a release agent, and crystallization, depending on the purpose. Various additives such as an accelerator, a nucleating agent, and an epoxy compound may be included.

[Thermal conductive resin composition]
The heat conductive resin composition in the present invention preferably accounts for 80% by mass or more in total of the thermoplastic polyester resin (A), the thermoplastic polyester elastomer (B), the graphite (C), and the carbodiimide compound (D), More preferably, it accounts for 90% by mass or more, even more preferably 95% by mass or more.

  The heat conductive resin composition of the present invention is produced by melt-kneading a thermoplastic polyester resin (A), a thermoplastic polyester elastomer (B), graphite (C), and other components. In general, graphite tends to be crushed during melt-kneading or forming, so that the larger the average particle size of graphite before melt-kneading, the larger the average particle size of graphite after melt-kneading or forming. As a result, thermal conductivity and moldability are improved. At the time of melt-kneading, graphite (C) is generally added together with a resin from a hopper and kneaded, but as described above, in order to suppress crushing as much as possible and maintain good thermal conductivity, flake graphite is particularly preferred. (C-1) is preferably added by side feed in the latter half of the step of melt-kneading.

  The molded article obtained by injection molding from the thermally conductive resin composition of the present invention has a thermal conductivity in the plane direction of 5 W / (m · K) or more, and the thermally conductive resin composition of the present invention has a width of 10 mm. The flow length in a shape having a thickness of 2 mm (measurement conditions: cylinder temperature 280 ° C., mold temperature 140 ° C., pressure 60 MPa) is 200 mm or more.

  The “thermal conductivity in the plane direction” as used in the present invention indicates the thermal conductivity in the direction in which the molten resin flows when a molded article is produced. The thermal conductivity in the plane direction of the heat conductive resin composition of the present invention is 5 W / (m · K) or more, preferably 6 W / (m · K) or more. The upper limit is not particularly limited, and the higher the better, the better, but it is considered to be about 10 W / (m · K) from the configuration of the heat conductive resin composition of the present invention. The molding conditions of the molded article and the method of measuring the thermal conductivity are as described in Examples below.

  The above-mentioned flow length of the heat conductive resin composition of the present invention is at least 200 mm, preferably at least 210 mm, more preferably at least 220 mm. The upper limit is not particularly limited, but about 300 mm is considered to be the upper limit. The method for measuring the flow length is as described in Examples below.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Examples 1 to 7 and Comparative Examples 1 to 7>
In Examples 1 to 7 and Comparative Examples 1 to 7, the following materials were used as components of the thermally conductive resin composition.

[Thermoplastic polyester resin (A)]
A-1: Polyethylene terephthalate (manufactured by Toyobo Co., Ltd., intrinsic viscosity (IV) = 0.63 dl / g)
[Thermoplastic polyester elastomer (B)]
B-1: Polyester elastomer (Perprene P-70B manufactured by Toyobo Co., Ltd.)
[Graphite (C)]
C-1-1: Flake graphite manufactured by Nippon Graphite Industry Co., Ltd. (average particle diameter 200 μm)
C-1-2: flaky graphite 50M (average particle diameter 300 μm) manufactured by Nippon Graphite Industry Co., Ltd.
C-1-3: Flake graphite BF-30AK (average particle diameter 30 μm) manufactured by Chuetsu Graphite Industry Co., Ltd.
C-1-4: Scaly graphite manufactured by Nippon Graphite Industry Co., Ltd. (average particle diameter 600 μm)
C-2-1: Expandable graphite GFP-20 manufactured by GRAFTECH (average particle diameter: 20 μm)
C-2-2: Expandable graphite GFP-200 manufactured by GRAFTECH (average particle diameter 200 μm)
Each of the scale-like graphites C-1-1 to C-1-4 had a fixed carbon concentration of 96%. The above average particle diameter is defined as the average particle diameter of a graphite sample in a 20% by weight aqueous solution of sodium hexametaphosphate in a 100 ml beaker, dispersed by an ultrasonic disperser for 30 minutes, and dispersed by a laser scattering particle sizer (MICROTRAC HRA ( It was placed in a chamber of Nikkiso Co., Ltd. 9320-X100, and the volume distribution was measured at a measurement time of 120 seconds. The particle size of 50% of the measured volume distribution was defined as the average particle size.
[Carbodiimide compound (D)]
D-1: Carbodiimide compound Carbodilite LA-1 (aliphatic carbodiimide) manufactured by Nisshinbo Chemical Inc.
[Other additives]
Antioxidant: IRGANOX1010 Release agent manufactured by BASF: LICOWAX-OP Crystallization accelerator manufactured by Clariant: KRM4004 manufactured by Sanyo Chemical Industry Co., Ltd.

The components shown in Tables 1 and 2 were dry-blended at the ratios shown in Tables 1 and 2 (parts by mass), and the cylinder temperature was 270 using a twin-screw extruder (TEX-30 manufactured by Nippon Steel Works, Ltd.). The mixture was melt-kneaded at a temperature of 10 ° C., a discharge rate of 10 kg / hr, and a screw rotation speed of 150 rpm to produce pellets of the thermally conductive resin composition. A test piece was prepared using the obtained pellet, and the thermal conductivity (plane direction), fluidity, and toughness of the thermally conductive resin composition were measured. Table 1 shows the measurement results of the thermally conductive resin compositions of Examples 1 to 7.
Table 2 also shows the measurement results of the thermal conductivity (plane direction), fluidity, and toughness of the thermally conductive resin compositions of Comparative Examples 1 to 7. In addition, each physical property of the heat conductive resin composition was measured according to the following method.

<Thermal conductivity>
Using an injection molding machine manufactured by Toshiba Machine Co., Ltd., a flat plate having a shape of 100 mm × 100 mm × 1 mm (thickness) is formed by injection molding at a cylinder temperature of 280 ° C. and a mold temperature of 140 ° C. The part was cut into a 25 mm × 25 mm square, and the thermal diffusion coefficient and the specific heat capacity in the plane direction (flow direction of the resin) were measured by a laser flash method using TC-7000H manufactured by Alpac Riko Co., Ltd. The thermal conductivity was determined by calculation using the numerical values and the specific gravities separately measured with the same molded product.

<Fluidity evaluation>
Using an injection molding machine manufactured by Toshiba Machine Co., Ltd., a flow length evaluation mold having a flow path of 10 mm in width and 2 mm in thickness, the injection pressure is 60 MPa, the cylinder temperature is 280 ° C., and the mold temperature is 140 ° C., and the cycle is continuous for 30 s. 20 shot injection molding was performed, and the flow length of the 20th shot was measured.

<Toughness (bending deflection rate)>
It was measured according to ISO-178. The test piece was injection molded under the conditions of a cylinder temperature of 280 ° C. and a mold temperature of 140 ° C.

  As is clear from Tables 1 and 2, the thermally conductive resin compositions of Examples 1 to 7 of the present invention are obtained by blending a polyester elastomer with a thermoplastic resin, and extruding flaky graphite having a specific particle size. Thermal conductivity, fluidity, and toughness are balanced by mixing graphite in a specific range of ratios, whereas Comparative Examples 1 to 7 show thermal conductivity, fluidity, and toughness. One or two or more items are low. Comparing Example 1 with Example 3, the former containing the carbodiimide compound resulted in higher thermal conductivity.

According to the present invention, since a resin composition having excellent fluidity, toughness, and thermal conductivity can be obtained, it can be suitably used for applications in which heat generation is a problem, and can be used in place of a metal or the like. Since it becomes possible to reduce the weight, improve the degree of freedom of the shape, and easily obtain a molded product, it greatly contributes to the industry.

Claims (5)

  It is a heat conductive resin composition containing a thermoplastic polyester resin (A), a thermoplastic polyester elastomer (B), and graphite (C), the content of each being (A) being 30 to 55 parts by mass, ( B) is 5 to 20 parts by mass, (C) is 25 to 60 parts by mass ((A) + (B) + (C) = 100 parts by mass), and a molded product obtained from the heat conductive resin composition The flow length (measurement conditions: cylinder temperature 280 ° C., mold temperature 140 ° C., pressure 60 MPa) of a shape having a thermal conductivity of 5 W / (m · K) or more, a width of 10 mm and a thickness of 2 mm in a surface direction of 200 mm or more A thermally conductive resin composition, characterized in that:   The graphite (C) is composed of flaky graphite (C-1) having an average particle diameter of 200 to 400 μm and expandable graphite (C-2) having an average particle diameter of 10 to 40 μm, and the mass ratio thereof is flaky. The thermally conductive resin composition according to claim 1, wherein graphite (C-1) / expandable graphite (C-2) is in a range of 100/0 to 78/22.   The heat conductive resin composition according to claim 1, wherein the thermoplastic polyester resin (A) is polyethylene terephthalate.   The heat conductive resin composition according to any one of claims 1 to 3, further comprising a carbodiimide compound (D). A molded article comprising the thermally conductive resin composition according to claim 1.