JP7560381B2 - Resin composition and method for producing same - Google Patents

Description

The present invention relates to a resin composition consisting of a polyarylene sulfide resin, a polyetherimide, and graphite, which has excellent thermal conductivity and electrical insulation properties while maintaining excellent strength.

Polyarylene sulfide resin is an engineering plastic with excellent chemical resistance, heat resistance, and mechanical properties. For this reason, polyarylene sulfide resin is widely used in electrical and electronic applications, vehicle-related applications, aircraft, housing facilities, and other applications, taking advantage of its excellent properties. In recent years, power consumption has increased with the high integration of LSIs, and heat generation can cause electronic components to malfunction or even damage the electronic components themselves, which has become a problem. Therefore, heat sinks have been installed as a heat dissipation measure to dissipate the generated heat. Traditionally, ceramics with high heat dissipation and insulation properties were generally used for heat sinks, but ceramics need to be cut one by one, which is time-consuming to process, and this has led to cost issues. Therefore, from the perspective of moldability, attempts have been made to increase thermal conductivity by blending heat dissipation fillers with thermoplastic resins, including polyarylene sulfide resins. Attempts to improve the thermal conductivity of polyarylene sulfide resins have been proposed, for example, in a resin composition in which alumina and an inorganic filler are mixed with polyarylene sulfide resin to enhance thermal conductivity (Patent Document 1) and in which alumina, glass fiber, and talc are mixed with polyarylene sulfide resin to enhance thermal conductivity (Patent Document 2). However, the thermal conductivity is not sufficient, and there is a problem of a decrease in physical properties due to high filler loading. In addition, a resin composition consisting of polyarylene sulfide resin, an amorphous resin with a glass transition temperature of 140° C. or higher, and graphite (Patent Document 3) has been proposed, but there is no mention of electrical insulation.

JP 2002-256147 A JP 2013-75996 A JP 2003-268236 A

The object of the present invention is to provide a resin composition that has excellent thermal conductivity and electrical insulation while maintaining excellent strength.

As a result of extensive research, the inventors discovered that a resin composition consisting of polyarylene sulfide resin, polyetherimide and graphite is a resin composition that has excellent thermal conductivity and electrical insulation while maintaining excellent strength, and thus arrived at the present invention.

Specifically, the above-mentioned object is achieved by a resin composition containing 100 parts by weight of (A) polyarylene sulfide resin (component A), 5 to 100 parts by weight of (B) polyetherimide (component B), and 5 to 100 parts by weight of (C) graphite (component C), in which component A is a polyarylene sulfide resin obtained by a method in which a diiodoaryl compound, solid sulfur, and a polymerization terminator and/or a polymerization reaction catalyst are polymerized by directly heating without using a polar solvent.

The details of the present invention are described below.

(Component A: Polyarylene sulfide resin)
The polyarylene sulfide resin used as component A in the present invention is a polyarylene sulfide resin obtained by a method of directly heating and polymerizing a diiodoaryl compound, solid sulfur, and a polymerization terminator and/or a polymerization catalyst without using a polar solvent. Among them, a polyarylene sulfide resin having a phenyl group as a terminal group is preferred.

The polyarylene sulfide resin may be composed of, for example, p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, diphenylene sulfide units, phenylene sulfide units containing a substituent, phenylene sulfide units containing a branched structure, etc., as its constituent units. Among these, those containing 70 mol % or more, particularly 90 mol % or more of p-phenylene sulfide units are preferred, and poly(p-phenylene sulfide) is even more preferred.

The polyarylene sulfide resin used as component A of the present invention preferably has a polydispersity (Mw/Mn) expressed by the weight average molecular weight (Mw) and the number average molecular weight (Mn) of 2.7 or more, more preferably 2.8 or more, and even more preferably 2.9 or more. If the polydispersity is less than 2.7, there may be a large amount of burrs generated during molding. The upper limit of the polydispersity (Mw/Mn) is not particularly specified, but it is preferably 10 or less. Here, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values calculated in terms of polystyrene by gel permeation chromatography (GPC). 1-chloronaphthalene was used as the solvent, and the column temperature was 210°C.

Methods for producing polyarylene sulfide resins include, for example, those described in U.S. Patents Nos. 4,746,758 and 4,786,713, JP-T-2013-522385, JP-A-2012-233210, and JP-A-5167276.

The manufacturing method includes an iodization step and a polymerization step. In the iodization step, an aryl compound is reacted with iodine to obtain a diiodoaryl compound. In the subsequent polymerization step, the diiodoaryl compound is polymerized with solid sulfur using a polymerization terminator to produce a polyarylene sulfide resin. Iodine is generated in gaseous form in this step, and is recovered and used again in the iodization step. Iodine is essentially a catalyst.

A representative example of solid sulfur used in the above-mentioned preparation method is cyclooctasulfur (S ₈ ) in which eight atoms are linked at room temperature. However, the sulfur compound used in the polymerization reaction is not limited, and any form may be used as long as it is solid or liquid at room temperature.

Representative diiodoaryl compounds used in the above-mentioned production method include at least one selected from the group consisting of diiodobenzene, diiodonaphthalene, diiodobiphenyl, diiodobisphenol, and diiodobenzophenone. Also used are derivatives of iodoaryl compounds to which an alkyl group or a sulfone group is bonded, or to which oxygen or nitrogen is introduced. Iodoaryl compounds are classified into different isomers depending on the bonding position of the iodine atom, and preferred examples of these isomers are compounds in which iodine is symmetrically located at both ends of the molecule of the aryl compound, such as p-diiodobenzene, 2,6-diiodonaphthalene, and p,p'-diiodobiphenyl. The content of the iodoaryl compound is preferably 500 to 10,000 parts by weight based on 100 parts by weight of the solid sulfur. This amount is determined in consideration of the formation of disulfide bonds.

Typical polymerization terminators used in the above manufacturing method include diphenyl sulfide and diphenyl disulfide. The content of the polymerization terminator is preferably 1 to 30 parts by weight per 100 parts by weight of the solid sulfur. This amount is determined taking into consideration the formation of disulfide bonds.

In the above-mentioned production method, a polymerization catalyst may be used, and a representative example of the polymerization catalyst is a nitrobenzene-based catalyst. A preferred example of the nitrobenzene-based catalyst is at least one selected from the group consisting of 1,3-diiodo-4-nitrobenzene, 1-iodo-4-nitrobenzene, 2,6-diiodo-4-nitrophenol, iodonitrobenzene, and 2,6-diiodo-4-nitroamine. The content of the polymerization catalyst is preferably 0.01 to 20 parts by weight per 100 parts by weight of the solid sulfur. This amount is determined taking into consideration the formation of disulfide bonds.

By using this polymerization method, graphite is distributed unevenly in the polyetherimide phase, providing good electrical insulation.

(Component B: Polyetherimide)
The polyetherimide, which is the component B of the present invention, is a resin containing a cyclic imide structure, and is not particularly limited as long as it can be used for the purpose of the present invention, but a polyetherimide containing an aliphatic or aromatic ether unit and a cyclic imide group as a repeating unit is preferred. Furthermore, the main chain of the polyimide may contain structural units other than the cyclic imide and ether units, such as aromatic or aliphatic ester units, oxycarbonyl units, etc., within a range that does not impair the effects of the present invention.

Specific examples of polyetherimides that can be preferably used in the present invention include polyetherimides represented by the following formula (1):

(In the formula, n represents an integer of 2 or more.)

In formula (1), R ₁ is a divalent aromatic or aliphatic group containing 6 to 30 carbon atoms, and R ₂ is a divalent organic group selected from the group consisting of a divalent aromatic residue having 6 to 30 carbon atoms, an alkylene group having 2 to 20 carbon atoms, a cycloalkylene group having 2 to 20 carbon atoms, and a polydiorganosiloxane group chain-terminated with an alkylene group having 2 to 8 carbon atoms.

Examples of R ₁ and R ₂ include aromatic residues and alkylene groups represented by the following formulas (2) to (8).

(In formula (8), n represents an integer of 2 or more.)

An example of such a polyetherimide is "ULTEM1010" manufactured by SABIC Japan LLC.

The content of component B is 5 to 100 parts by weight, preferably 15 to 80 parts by weight, and more preferably 20 to 60 parts by weight, per 100 parts by weight of component A. If the content of component B is less than 5 parts by weight, sufficient electrical insulation cannot be obtained. On the other hand, if it exceeds 100 parts by weight, electrical insulation and mechanical strength decrease.

(Component C: graphite)
The graphite used as the C component of the present invention may be any graphite that is generally called graphite. The type of graphite is not particularly limited, such as scaly graphite, flake graphite, expanded graphite, and artificial graphite. However, from the viewpoint of thermal conductivity, expanded graphite that has been thermally expanded is particularly preferred. Expanded graphite is generally obtained by heat-treating natural graphite, petroleum coke, petroleum pitch, amorphous carbon, etc., which is naturally produced as a mineral, at 2000°C or higher to artificially orient irregularly arranged fine graphite crystals, immersing the artificial graphite in concentrated sulfuric acid, concentrated nitric acid, etc., and further treating it with an oxidizing agent such as hydrogen peroxide or hydrochloric acid to generate a graphite intercalation compound, and then washing with water and rapidly heating at 800 to 1000°C to expand the graphite in the C-axis direction of the raw graphite, but the heat treatment temperature, acid treatment components, etc. are not particularly limited. The particle size of the graphite is preferably 1 to 1000 μm, more preferably 10 to 500 μm. If the particle size is less than 1 μm, the thermal conductivity may be poor, whereas if it exceeds 1000 μm, the appearance of the molded product may be poor.

The surface of the graphite in the present invention may be subjected to a surface treatment in order to increase its affinity with polyetherimide, so long as this does not impair the properties of the composition of the present invention. Furthermore, a mixture of two or more types of graphite may be used.

The content of component C is 5 to 100 parts by weight, preferably 10 to 80 parts by weight, and more preferably 20 to 60 parts by weight, per 100 parts by weight of component A. If the content of component C is less than 5 parts by weight, sufficient thermal conductivity cannot be obtained, and if it exceeds 100 parts by weight, productivity or moldability decreases, and in the worst case, extrusion molding becomes impossible.

(Component D: Fibrous filler)
Examples of the fibrous filler used as component D of the present invention include glass fiber, aramid fiber, potassium titanate whisker, zinc oxide whisker, alumina fiber, ceramic fiber, asbestos fiber, gypsum fiber, etc., which may be hollow, and two or more of these fibrous fillers can be used in combination. In addition, it is preferable to pretreat these fibrous fillers with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound in order to obtain better mechanical strength.

Among these fibrous fillers, glass fiber is preferably used. The glass fiber may be any glass fiber that is generally called glass fiber. The glass composition such as A glass, C glass, E glass, etc. is not particularly limited, and may contain TiO ₂ , SO ₃ , P ₂ O _5, etc., depending on the case. However, E glass (alkali-free glass) is more preferable when it is mixed with polyarylene sulfide resin. The glass fiber is made by quenching molten glass while stretching it by various methods to form a predetermined fiber shape. The quenching and stretching conditions in such a case are also not particularly limited. In addition to a perfect circle, the cross-sectional shape may be an ellipse, a cocoon, a three-leaf clover, or other shape other than a perfect circle. Furthermore, a mixture of a perfect circle glass fiber and a shape other than a perfect circle glass fiber may be used. The above glass fiber may be coated or bundled with a resin such as an ethylene/vinyl acetate copolymer, polyurethane, or epoxy resin.

The content of component D is preferably 5 to 100 parts by weight, more preferably 10 to 90 parts by weight, and even more preferably 20 to 80 parts by weight, per 100 parts by weight of component A. If the content is less than 5 parts by weight, sufficient mechanical strength may not be obtained, while if it exceeds 100 parts by weight, production processability may be poor.

(Component E: Non-fibrous filler)
The resin composition of the present invention may be used in combination with a non-fibrous filler within the scope of not impairing the effects of the present invention. The non-fibrous filler is not particularly limited, and examples thereof include sericite, kaolin, mica, clay, bentonite, asbestos, talc, silicates such as alumina silicate, swellable layered silicates such as montmorillonite and synthetic mica, metal compounds such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide and iron oxide, carbonates such as calcium carbonate, magnesium carbonate and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads, ceramic beads, boron nitride, silicon carbide, calcium phosphate and silica.

The content of component E is preferably 5 to 100 parts by weight, more preferably 5 to 80 parts by weight, and even more preferably 10 to 60 parts by weight, per 100 parts by weight of component A. If the content of component E is less than 5 parts by weight, a sufficient reinforcing effect may not be obtained, and if it exceeds 100 parts by weight, productivity or moldability may decrease, and in the worst case, extrusion molding may become impossible.

The resin composition of the present invention may contain an elastomer component to the extent that the effect of the present invention is not impaired. Suitable elastomer components include core-shell graft copolymer resins such as acrylonitrile-butadiene-styrene copolymer (ABS resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin) and silicone-acrylic composite rubber graft copolymer, or thermoplastic elastomers such as silicone-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyester-based thermoplastic elastomers and polyurethane-based thermoplastic elastomers.

The resin composition of the present invention may contain, within the scope of the effect of the present invention, antioxidants and heat stabilizers (hindered phenols, hydroquinones, phosphites, and their substitutes, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.), release agents and lubricants (montanic acid and its metal salts, its esters, its half esters, stearyl alcohol, stearamide, various bisamides, bisureas, polyethylene wax, etc.), pigments (cadmium sulfide, phthalic acid, etc.), and the like. cyanine, carbon black, etc.), dyes (nigrosine, etc.), crystal nucleating agents, plasticizers (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), flame retardants (red phosphorus, phosphate esters, melamine cyanurate, hydroxides such as magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.) and other polymers can be added.

(Production of resin composition)
The resin composition of the present invention can be produced by mixing the above-mentioned components simultaneously or in any order using a mixer such as a tumbler, V-type blender, Nauter mixer, Banbury mixer, kneading roll, or extruder. Melt kneading using a twin-screw extruder is preferable, and if necessary, any component is preferably fed into the other melt-mixed components from a second feed port using a side feeder or the like. The resin extruded as described above is directly cut and pelletized, or is pelletized by cutting the strands with a pelletizer after forming them. When it is necessary to reduce the influence of external dust during pelletization, it is preferable to purify the atmosphere around the extruder. The shape of the obtained pellets can be a general shape such as a cylinder, a rectangular column, or a sphere, but is more preferably a cylinder. The diameter of such a cylinder is preferably 1 to 5 mm, more preferably 1.5 to 4 mm, and even more preferably 2 to 3.5 mm. On the other hand, the length of the cylinder is preferably 1 to 30 mm, more preferably 2 to 5 mm, and even more preferably 2.5 to 4 mm.

(About molded products)
Molded articles using the resin composition of the present invention can be obtained by molding the pellets produced as described above. Preferably, they are obtained by injection molding or extrusion molding. Injection molding includes not only ordinary molding methods, but also injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including a method of injecting a supercritical fluid), insert molding, in-mold coating molding, heat-insulating mold molding, rapid heating and cooling mold molding, two-color molding, multi-color molding, sandwich molding, and ultra-high speed injection molding. Molding can be performed using either a cold runner method or a hot runner method. In addition, extrusion molding can produce various profile extrusion molded products, sheets, films, and the like. Sheets and films can also be molded using an inflation method, a calendar method, a casting method, and the like. Furthermore, it is possible to mold the resin composition of the present invention into a heat-shrinkable tube by applying a specific stretching operation. It is also possible to mold the resin composition of the present invention into a molded article by rotational molding, blow molding, and the like.

The resin composition of the present invention has excellent thermal conductivity and electrical insulation while maintaining excellent strength, and is therefore suitable for use in a wide range of electronic components including sensors, LED lamps, connectors, small switches, coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, hard disk drive parts (hard disk drive hubs, actuators, hard disk substrates, etc.), DVD parts (optical pickups, etc.), motor brush holders, parabolic antennas, computer-related parts, etc.; VTR parts, television parts, irons, hair It can also be used for a variety of applications, including dryers, rice cooker parts, microwave oven parts, audio parts, audio equipment parts such as audio, laser discs (registered trademark), and compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, and word processor parts; machine-related parts such as office computer-related parts, telephone-related parts, facsimile-related parts, copier-related parts, cleaning jigs, motor parts, lighters, and typewriters; optical equipment and precision machinery-related parts such as microscopes, binoculars, cameras, and clocks; and vehicle parts such as lamp reflectors, lamp housings, center console panels, deflector parts, car navigation parts, and automobile computer parts.

The present inventors currently consider the best form of the present invention to be a combination of the preferred ranges of each of the above-mentioned requirements, and representative examples are described in the following examples. Of course, the present invention is not limited to these forms.

[Evaluation of Resin Composition]
(1) Tensile strength at break: Measured according to ISO 527 (measurement condition: 23°C). The test pieces were molded by the following method. The larger this value, the better the mechanical strength of the resin composition. (2) Thermal conductivity: A square plate (50 mm x 100 mm x 4 mmt) was molded under the following conditions, and the thermal conductivity of the sample in the flow direction was measured by the laser flash method. The larger this value, the better the thermal conductivity of the resin composition.
(3) Electrical insulation A square plate (150×150×3 mmt) was molded under the following conditions, and a central piece of 50×50×3 mmt was cut out. The volume resistivity of the cut square plate was measured using a super insulation meter (manufactured by HIOKI Corporation).

[Examples 1 to 8, Comparative Examples 1 to 5]
The polyarylene sulfide resin, polyetherimide, graphite, fibrous filler and non-fibrous filler were melt-kneaded using a vented twin-screw extruder in the amounts shown in Table 1 to obtain pellets. The vented twin-screw extruder used was TEX30α-38 (fully interlocked, rotating in the same direction) manufactured by Japan Steel Works, Ltd. The extrusion conditions were a discharge rate of 20 kg/h, a screw rotation speed of 200 rpm, a vent vacuum of 3 kPa, and an extrusion temperature of 320°C from the first feed port to the die portion. The fibrous filler and graphite were fed from the second feed port using a side feeder of the extruder, and the polyarylene sulfide resin, polyetherimide and non-fibrous filler were fed to the extruder from the first feed port. The first feed port here refers to the feed port farthest from the die, and the second feed port refers to the feed port located between the die and the first feed port of the extruder. The obtained pellets were dried in a hot air circulation dryer at 130°C for 6 hours, and then molded into test pieces for evaluation using an injection molding machine (EC160NII-4Y, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 320°C and a mold temperature of 140°C.

The components represented by symbols in Table 1 are as follows.
<Component A>
A-1: Polyphenylene sulfide resin obtained by the following manufacturing method [Manufacturing method]
300.00 g of paradiiodobenzene and 27.00 g of sulfur were added with 0.60 g of diphenyl disulfide (0.65 wt% based on the weight of the final polymerized polyphenylene sulfide resin) as a polymerization terminator, and heated to 180° C. to completely melt and mix them, and then the temperature was increased to 220° C. and the pressure was reduced to 200 Torr. The mixture was polymerized for 8 hours while the temperature and pressure were gradually changed so that the final temperature and pressure were 320° C. and 1 Torr, respectively, to produce a polyphenylene sulfide resin. The dispersity (Mw/Mn) expressed by the weight average molecular weight (Mw) and the number average molecular weight (Mn) was 4.3.

A-2: Polyphenylene sulfide resin obtained by the following manufacturing method [Manufacturing method]
In a 15-liter autoclave equipped with a stirrer, 1814 g of flake sodium sulfide (Na ₂ S.2.9H ₂ O), 8.7 g of granular caustic soda (100% NaOH: Wako Pure Chemical special grade) and 3232 g of N-methyl-2-pyrrolidone were charged, and the temperature was gradually raised to 200°C while stirring under a nitrogen stream, and 339 g of water was distilled off. After cooling to 190°C, 2129 g of p-dichlorobenzene and 1783 g of N-methyl-2-pyrrolidone were added, and the system was sealed under a nitrogen stream. The system was heated to 225°C over 2 hours, polymerized at 225°C for 1 hour, then heated to 250°C over 25 minutes, and polymerized at 250°C for 2 hours. Next, 509 g of distilled water was injected into the system at 250°C, and the system was heated to 255°C and polymerized for another 2 hours. After the polymerization was completed, the mixture was cooled to room temperature, and the polymerization slurry was subjected to solid-liquid separation using a centrifugal filter. The cake was washed three times with N-methyl-2-pyrrolidone and acetone in sequence under a nitrogen stream, and further washed with 0.2% hydrochloric acid and warm water in sequence under a nitrogen stream. The obtained poly(p-phenylene sulfide) was dried at 105° C. for one day to obtain a polyarylene sulfide resin.

<Component B>
B-1: Polyetherimide (ULTEM1010 (product name) manufactured by SABIC Japan, LLC)
<Component C>
C-1: Expanded graphite (E-40, manufactured by Nishimura Graphite Co., Ltd., average particle size: 250 μm)
C-2: Scaly graphite (10099M, manufactured by Nishimura Graphite Co., Ltd., average particle size: 54 μm)
<Component D>
D-1: Circular cross-section chopped glass fiber (T-732H manufactured by Nippon Electric Glass Co., Ltd., diameter: 10.5 μm, cut length: 3 mm, urethane/epoxy-based bundling agent)
<Component E>
E-1: Talc (IMI-FABI Ultra5L, average particle size 2 μm)

Claims (5)

The present invention relates to a method for producing a resin composition comprising 100 parts by weight of a polyarylene sulfide resin (component A) obtained by a method of directly heating and polymerizing (A) a diiodoaryl compound, solid sulfur, and a polymerization terminator and/or a polymerization reaction catalyst without using a polar solvent , and the method comprises the steps of : (B) 5 to 100 parts by weight of a polyetherimide (component B); and (C) 5 to 100 parts by weight of graphite (component C). 2. The method for producing a resin composition according to claim 1, wherein the terminal group of component A is a phenyl group. 3. The method for producing a resin composition according to claim 1, wherein the component C is graphite that has been thermally expanded. The method for producing a resin composition according to any one of claims 1 to 3, characterized in that the resin composition contains 5 to 100 parts by weight of a fibrous filler (D) (Component D) per 100 parts by weight of Component A. The method for producing a resin composition according to any one of claims 1 to 4, characterized in that the resin composition contains 5 to 100 parts by weight of a non-fibrous filler (E) (Component E) per 100 parts by weight of Component A.