JP2012167250A - Molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced propylene-based resin composition for obtaining a molded article which satisfies an insulation property and electromagnetic wave shielding property, and is excellent in mechanical characteristics.SOLUTION: The molded article is formed by molding a resin composition obtained by blending (B) 5-64 pts.wt. of carbon fiber and (C) 0.1-18 pts.wt. of an insulating inorganic filler to (A) 100 pts.wt. of polyolefin-based resin comprising (A-1) a modified polyolefin-based resin and (A-2) an unmodified polyolefin-based resin.

Description

  The present invention relates to a molded article, and relates to a molded article having both electromagnetic shielding properties and insulating properties and excellent mechanical properties.

  Compositions composed of reinforcing fibers and thermoplastic resins are widely used in sports equipment applications, aerospace applications and general industrial applications because they are lightweight and have excellent mechanical properties. Reinforcing fibers used in these fiber-reinforced thermoplastic resin compositions reinforce molded products in various forms depending on the intended use. Among the reinforcing fibers, carbon fibers are particularly preferable from the viewpoint of the balance of specific strength, specific rigidity, and lightness, and among them, polyacrylonitrile-based carbon fibers are preferably used.

  A thermoplastic material reinforced with carbon fibers, particularly long-fiber carbon fibers, is an excellent conductive material, and the resulting molded article has excellent electromagnetic shielding properties, so that it can be used for storage containers for electrical components that generate electromagnetic waves. . However, when used around electrical components, if the container is conductive when it is damaged by impact or the like, there is a possibility that electrical wiring and terminals will be short-circuited. Further, there is a risk of electric shock when a person touches the container while the container is conductive.

  As a resin composition of a polyolefin resin reinforced with carbon fiber, Patent Document 1 describes a melt-kneaded composition comprising a polyolefin resin, carbon fiber and / or an inorganic filler, and an amine compound. The molded article made of the described resin composition has no combination of carbon fiber and inorganic filler, and has insufficient insulation. Further, the fiber length of the molded product is shortened by melt-kneading, and the electromagnetic shielding properties are also inferior. Patent Document 2 describes a polyolefin resin composition (masterbatch) in which a carbon fiber obtained by melt-kneading polyolefin and carbon fiber has a specific fiber length. The specific fiber length is a fiber length remaining in a molded product. However, since the fiber length is not yet molded, the fiber length contained in the molded product is short and inferior in electromagnetic shielding properties. Patent Document 3 describes a melt-kneaded composition made of polypropylene reinforced with an inorganic filler and carbon fiber, but does not describe any modified polyolefin, is inferior in mechanical properties and insulation, and is melt-kneaded. Since the resin composition is manufactured, the fiber length of the molded product after injection molding is short, and the electromagnetic shielding properties are also inferior.

  As described above, in the conventional technology, when a polyolefin resin is molded as a matrix, carbon fiber reinforcement with excellent electromagnetic shielding properties, insulating properties, and mechanical properties cannot be achieved at the same time. Development of a molded product was desired.

JP 58-204043 A JP 2006-124454 A JP 2005-232413 A

  In view of the background of the prior art, an object of the present invention is to provide a molded article that has both insulating properties and electromagnetic wave shielding properties and excellent mechanical properties when a polyolefin resin is used as a matrix.

As a result of intensive studies to achieve the above object, the present inventors have found the following molded product that can achieve the above-mentioned problems.
(1) With respect to 100 parts by weight of (A) polyolefin resin consisting of (A-1) modified polyolefin resin and (A-2) unmodified polyolefin resin,
(B) 5 to 64 parts by weight of carbon fiber (C) Molded product obtained by blending 0.1 to 18 parts by weight of insulating inorganic filler, and (B) a weight average fiber of carbon fiber A molded product having a length of 0.3 to 10 mm.
(2) The resin composition is (A) 100% by weight of the polyolefin resin, (A-1) the modified polyolefin resin is more than 5% by weight and 99% by weight or less, (A-2) the unmodified polyolefin resin is The molded article according to (1), which is 1% by weight or more and less than 95% by weight.
(3) The molded article according to any one of (1) to (2), wherein the (A-1) modified polyolefin resin has at least one functional group selected from a carboxyl group and a carboxylic anhydride group. .
(4) The molded article according to any one of (1) to (3), wherein (A-1) the modified polyolefin resin and / or (A-2) the unmodified polyolefin resin is homopolypropylene.
(5) (C) The insulating inorganic filler is at least one selected from talc, mica, calcium carbonate, barium sulfate, titanium oxide and glass filler, and any one of (1) to (4) Articles described in 1.
(6) The molded article according to any one of (1) to (5), wherein the average particle size of the (C) insulating inorganic filler is 0.1 to 200 μm.
(7) The molded product according to any one of (1) to (6), wherein the molded product is an electrical component storage container.
(8) The molded article according to any one of (1) to (7), wherein the O / C of the carbon fiber is 0.10 to 0.30.
(9) (C) Insulating inorganic filler is (C-1) an insulating inorganic filler having an average particle diameter of 0.1 to 20 μm and (C-2) an insulating inorganic filler having an average particle diameter of 20 to 200 μm. The molded article according to any one of (1) to (8), which is in a range of (C-1) / (C-2) = 1/9 to 9/1.
(10) The molded article according to any one of (1) to (9), wherein the (A-1) modified polyolefin resin and / or (A-2) the unmodified polyolefin resin is block polypropylene.
(11) The molded article according to any one of (1) to (10), wherein the weight average fiber length of (B) carbon fiber is 0.8 to 2.0 mm.

  The molded product of the present invention is a molded product that has both insulating properties and electromagnetic wave shielding properties and is excellent in mechanical properties such as bending properties and impact resistance properties. Also, because it is a molded product using polyolefin resin, it has excellent lightness and is extremely useful for electrical / electronic equipment, OA equipment, home appliances, housings or parts of automobiles, especially electric parts storage containers for electric cars. is there.

It is a circuit diagram for measuring the volume resistivity of a molded product. It is a circuit diagram for measuring the insulation resistance value of a molded product.

  (A-1) A molded article comprising (A) a polyolefin resin, (B) carbon fiber, and (C) an insulating inorganic filler comprising a modified polyolefin resin and (A-2) an unmodified polyolefin resin. is there. First, these components will be described.

  The (A-1) modified polyolefin resin of the present invention is a polyolefin resin having a carboxyl group or a carboxylic anhydride group in the molecule. From the viewpoint of improving the mechanical properties and insulation of the resulting molded product, polypropylene is not used. It is preferable to modify and use at least one compound selected from saturated carboxylic acids, anhydrides or derivatives thereof.

  Furthermore, as polypropylene to be used, propylene homopolymer (homopolymer), propylene random copolymer (for example, propylene / ethylene random copolymer) with other olefin component containing 70 wt% or more of propylene component in addition to homopolymer, Examples include propylene block copolymers (such as propylene / ethylene random copolymers). Among them, the propylene block copolymer is preferable because of its good balance in mechanical properties.

  By using a modified polyolefin resin, adhesion with carbon fibers is improved, so mechanical properties are improved, and adhesion with carbon fibers is improved, so that the insulation properties of the carbon fiber surface are increased and insulation is improved. A molded product with excellent properties can be obtained. Examples of the compound selected from unsaturated carboxylic acid, acid anhydride or derivative thereof used for modification include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, methylmaleic acid, Methyl fumaric acid, mesaconic acid, citraconic acid, glutaconic acid and metal salts of these carboxylic acids, methyl hydrogen maleate, hydrogen itaconic acid methyl, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxy acrylate Ethyl, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, dimethyl maleate, dimethyl itaconate, maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo- ( 2,2,1) 5-heptene-2,3-dicarboxylic acid, endobicyclo- (2,2,1) -5-heptene-2,3-dicarboxylic anhydride, maleimide, N-ethylmaleimide, N-butylmaleimide, N-phenyl And maleimide, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citraconic acid, and 5-norbornene-2,3-dicarboxylic acid. Among these, unsaturated dicarboxylic acids and acid anhydrides thereof are preferable, and maleic acid, 5-norbornene-2,3-dicarboxylic acid or acid anhydrides thereof are particularly preferable.

  In addition, there is no particular limitation on the method for introducing a compound selected from these unsaturated carboxylic acids, acid anhydrides or derivatives thereof into the polyolefin resin, and the polyolefin resin and the unsaturated carboxylic acid, which are the main components, and acid anhydrides thereof are preliminarily used. Or a compound selected from the group consisting of derivatives thereof and graft-introducing into an unmodified polyolefin resin using a compound selected from unsaturated carboxylic acid, acid anhydride or derivative thereof and a radical initiator. Can be used. The amount of the modifier component introduced is preferably 0.001 to 40 mol%, more preferably 0.01 to 35 mol%, based on the entire olefin monomer in the modified polyolefin resin.

  (A-1) The viscosity of the modified polyolefin resin is not particularly limited, but the MFR value under conditions of 230 ° C. and 2.16 kg in accordance with JIS K 7210-1999 is 0.5 to 600 g / 10 min. Preferably, it is 1 to 200 g / 10 minutes. If the MFR value is less than 0.5 g / 10 min, the flow of the carbon fiber becomes difficult at the time of injection molding. Therefore, poor dispersion of the carbon fiber may occur, and if the MFR is 600 g / 10 min or more (A-1) Since the mechanical properties of the modified polyolefin resin are lowered, the impact strength may be lowered, which is not preferable.

  Moreover, (A-1) this modified polyolefin resin can also use a commercial item, for example, QE800 (acid modified polypropylene: Mitsui Chemicals), QE500 (acid modified polypropylene: Mitsui Chemicals), etc. are mentioned.

  (A-2) The unmodified polyolefin resin is a propylene homopolymer (homopolymer), a propylene random copolymer (for example, propylene / ethylene random) with other olefin components containing 70% by weight or more of the propylene component in addition to the homopolymer. Copolymer) and propylene block copolymers (such as propylene / ethylene random copolymer). Among them, the propylene block copolymer is preferable because of its good balance in mechanical properties.

  The viscosity of the (A-2) unmodified polyolefin resin is not particularly limited, but the MFR value under conditions of 230 ° C. and 2.16 kg in accordance with JIS K 7210-1999 is 1 to 300 g / 10 min. Preferably, it is 5 to 200 g / 10 minutes. When the MFR value is less than 1 g / 10 min, the moldability is remarkably lowered, and the flow of the carbon fiber becomes difficult at the time of injection molding, so that the fiber breaks in the molded product, the strength is lowered, and the electromagnetic wave shielding property is lowered. If the MFR is 600 g / 10 min or more, the mechanical properties of the (A-2) unmodified polyolefin resin are lowered, and the impact strength may be lowered.

  (A-2) A commercially available product can be used as the unmodified polyolefin resin, for example, J137 (homopolypropylene: manufactured by Prime Polymer Co., Ltd.), MA1B (homopolypropylene: manufactured by Nippon Polypro Co., Ltd.), J226T (random polypropylene: primed). Polymer), J707G (block polypropylene: manufactured by Prime Polymer), and the like.

  The (A) polyolefin resin comprising (A-1) a modified polyolefin resin and (A-2) an unmodified polyolefin resin keeps the mechanical properties and insulation properties of the resin high, and the raw material cost is considered ( A) The polyolefin resin is 100% by weight, and the (A-1) modified polyolefin resin is preferably more than 5% by weight and not more than 99% by weight. More preferably, it is 7 to 50 weight%, More preferably, it is 10 to 30 weight%. (A-2) The unmodified polyolefin resin is preferably 1% by weight to less than 95% by weight. More preferably, it is 50 to 93 weight%, More preferably, it is 70 to 90 weight%.

  The carbon fiber (B) used in the present invention is not particularly limited, but high-strength and high-modulus carbon fibers can be used, and these may be used alone or in combination. Among these, PAN-based, pitch-based, rayon-based carbon fibers and the like can be mentioned. From the viewpoint of the balance between the strength and elastic modulus of the obtained molded product, PAN-based carbon fibers are more preferable.

  Further, (B) the carbon fiber has a surface oxygen concentration ratio [O / C] which is a ratio of the number of oxygen (O) and carbon (C) atoms on the fiber surface measured by X-ray photoelectron spectroscopy of 0.05. What is -0.5 is preferable, More preferably, it is 0.08-0.4, More preferably, it is 0.1-0.3. When the surface oxygen concentration ratio is 0.05 or more, the amount of functional groups on the surface of the carbon fiber can be secured, and a stronger adhesion to the polyolefin resin can be obtained. it can. Moreover, although there is no restriction | limiting in particular in the upper limit of surface oxygen concentration ratio, Generally it can be illustrated to 0.5 or less from the balance of the handleability of carbon fiber, and productivity.

(B) The surface oxygen concentration ratio of the carbon fiber is determined according to the following procedure by X-ray photoelectron spectroscopy. First, the sizing agent adhering to the carbon fiber surface with a solvent was removed. (B) After carbon fibers were spread and arranged on a copper sample support base, A1Kα1 and 2 were used as an X-ray source, and the inside of the sample chamber was Keep at 1 × 10 ⁸ Torr. The kinetic energy value (KE) of the main peak of C _1s is adjusted to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area E. Is obtained by drawing a straight base line in the range of 1191 to 1205 eV. O _1s peak area E. Is obtained by drawing a straight base line in the range of 947 to 959 eV.

Here, the surface oxygen concentration ratio is calculated as an atomic number ratio from the ratio of the O _1s peak area to the C _1s peak area using a sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, model ES-200 manufactured by Kokusai Electric Inc. is used, and the sensitivity correction value is set to 1.74.

  The means for controlling the surface oxygen concentration ratio [O / C] to 0.05 to 0.5 is not particularly limited. For example, techniques such as electrolytic oxidation, chemical oxidation, and vapor phase oxidation are used. Among these, electrolytic oxidation treatment is preferable.

Further, (B) sizing treatment of the carbon fiber is preferable. The sizing treatment is a treatment method in which a liquid (sizing liquid) containing a sizing agent is attached.
Although it does not specifically limit as a sizing agent, The compound which has functional groups, such as an epoxy group, a urethane group, an amino group, and a carboxyl group, can be used, These may use 1 type or 2 types or more together. The number of functional groups is preferably 2 or more, and more preferably 3 or more.

  Specific examples of the compound include polyfunctional epoxy resins, acid-modified polypropylene, and neutralized products of acid-modified polypropylene.

  Examples of the polyfunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, aliphatic epoxy resin, phenol novolac type epoxy resin and the like. Among these, (A) a bisphenol type epoxy resin that easily exhibits adhesion to a polyolefin resin is preferable, and a flexible bisphenol F type epoxy resin is particularly preferable. (B) By making it exist between the carbon fiber and the (A) polyolefin resin, (B) the carbon fiber and the (A) polyolefin resin are firmly adhered to each other, making it difficult to peel off. preferable.

  By applying a sizing agent to (B) carbon fiber, even if the addition amount is small, (B) the adhesive properties and the insulation of the molded product can be effectively adapted to the surface properties such as functional groups on the carbon fiber surface. Can be improved. In addition, it improves bundling, bending resistance, and abrasion resistance, and suppresses the occurrence of fluff and yarn breakage in the high-order processing step. It can also improve the high-order workability as a so-called paste and bundling agent. it can.

  The sizing agent adhesion amount is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 5% by mass or less, and 0.1% by mass with respect to the mass of (B) the carbon fiber alone. More preferably, the content is 2% by mass or less. If it is 0.01% by mass or less, the effect of improving adhesiveness is difficult to appear, and insulation is hardly exhibited. If it is 10% by mass or more, the physical properties of the molded product may be lowered.

  The sizing agent also includes other components such as bisphenol-type epoxy compounds, linear low molecular weight epoxy compounds, polyethylene glycol, polyurethane, polyester, emulsifiers and surfactants, viscosity adjustment, improved scratch resistance, improved fuzz resistance, It may be added for the purpose of improving the focusing property and improving the high-order workability.

  There are no particular restrictions on the means for applying the sizing agent, but there are, for example, a method of immersing in a sizing liquid through a roller, a method of contacting a roller to which the sizing liquid is adhered, and a method of spraying the sizing liquid in a mist form. . Moreover, although either a batch type or a continuous type may be sufficient, the continuous type which has good productivity and small variations is preferable. At this time, it is preferable to control the sizing solution concentration, temperature, yarn tension, and the like so that the amount of the sizing agent active ingredient attached to the carbon fiber is uniformly attached within an appropriate range. Moreover, it is more preferable to vibrate the carbon fiber with ultrasonic waves when applying the sizing agent.

  Although the drying temperature and drying time should be adjusted according to the amount of the compound attached, the time required for complete removal of the solvent used for applying the sizing agent and drying is shortened, while the thermal deterioration of the sizing agent is prevented, and carbon From the viewpoint of preventing the fiber bundle from becoming hard and deteriorating the spreadability of the bundle, the drying temperature is preferably 150 ° C. or higher and 350 ° C. or lower, and more preferably 180 ° C. or higher and 250 ° C. or lower. .

  Examples of the solvent used for the sizing agent include water, methanol, ethanol, dimethylformamide, dimethylacetamide, and acetone. Water is preferable from the viewpoint of easy handling and disaster prevention. Accordingly, when a compound insoluble or hardly soluble in water is used as a sizing agent, it is preferable to add an emulsifier and a surfactant and disperse in water. Specifically, as an emulsifier and a surfactant, styrene-maleic anhydride copolymer, olefin-maleic anhydride copolymer, formalin condensate of naphthalene sulfonate, anionic emulsifier such as sodium polyacrylate, Nonionic emulsifiers such as cationic emulsifiers such as polyethyleneimine and polyvinylimidazoline, nonylphenol ethylene oxide adducts, polyvinyl alcohol, polyoxyethylene ether ester copolymers, sorbitan ester ethyl oxide adducts, etc. can be used. A nonionic emulsifier having a small size is preferable because it does not easily inhibit the adhesive effect of the sizing agent.

  Moreover, there is no restriction | limiting in particular in the number of single yarns at the time of setting it as a carbon fiber bundle, It can use within the range of 100-350,000, Especially, it uses within the range of 1,000-250,000. It is preferable. Further, from the viewpoint of productivity of carbon fibers, those having a large number of single yarns are preferable, and it is preferable to use them within a range of 20,000 to 100,000.

  The content of (B) carbon fiber is preferably 5 to 64 parts by weight with respect to 100 parts by weight of (A) polyolefin-based resin, and if it is less than 5 parts by weight, the electromagnetic shielding properties and mechanical properties are inferior, and if it exceeds 64 parts by weight, insulation is achieved. Is inferior. From the viewpoints of insulation, electromagnetic shielding properties, and mechanical properties, it is preferably 7 to 50 parts by weight, more preferably 10 to 30 parts by weight.

  (C) The insulating inorganic filler preferably has an average particle diameter measured by a laser diffraction method of 0.1 to 200 μm. If the thickness is less than 0.1 μm, the insulating property is inferior, and if it exceeds 200 μm, the dispersibility and the moldability are inferior. Further, from the viewpoints of insulation and moldability, (C-1) an insulating inorganic filler having an average particle diameter of 0.1 to 20 μm and (C-2) an average particle diameter of 20 to 200 μm are (C-1) / (C-2) is more preferably used in the range of 1/9 to 9/1. Since the weight average fiber length of (B) carbon fiber contained in the molded product is 0.3 to 10 mm, (C) insulating properties with different particle diameters are required to stably improve the insulation in the molded product. It is preferable to use an inorganic filler because the insulating property can be improved efficiently without reducing the moldability.

  Examples of such (C) insulating inorganic filler include talc, mica, calcium carbonate, wollastonite, whisker, glass filler, barium sulfate, titanium oxide, etc. Among them, talc and mica are preferably used. . These (C) insulating inorganic fillers may be used alone or in combination of two or more. When two types are used, the combination of talc and mica does not deteriorate the moldability. In addition, it is preferable because the insulating property can be improved efficiently.

  (C) As for content of an insulating inorganic filler, 0.1-18 weight part is preferable. If the amount is less than 0.1 part by weight, the insulating property is poor, and if it exceeds 18 parts by weight, molding tends to be difficult or the specific gravity tends to be heavy. From the viewpoint of lightness and insulation, 0.5 to 15 parts by weight is preferable, 1 to 10 is more preferable, and 3 to 8 parts by weight is even more preferable.

  Moreover, the resin composition of this invention may contain another elastomer, a filler, and an additive in the range which does not impair the objective of this invention. Examples of these include, as elastomers, unmodified olefin elastomers, styrene elastomers, urethane elastomers, ester elastomers, amide elastomers, and the like. Specific examples of olefin elastomers include ethylene-α-olefins. Examples thereof include ethylene-propylene non-conjugated diene terpolymers such as copolymers, ethylene-propylene-ethylidene norbornene copolymers, and ethylene-propylene-hexadiene copolymers. Specific examples of styrene elastomers include styrene-butadiene, styrene-isoprene-styrene, styrene-butadiene-styrene, styrene-ethylene-butadiene-styrene, styrene-ethylene-propylene-styrene random copolymers, and blocks. Examples thereof include a copolymer, a hydrogenated product of the block copolymer, and an acrylonitrile-butadiene-styrene copolymer. Among these, an ethylene-α-olefin copolymer as the olefin elastomer is preferable because it has good compatibility with the (A) polyolefin resin and can effectively improve the impact resistance.

  Fillers and additives include dispersants, flame retardants, crystal nucleating agents, UV absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers, release agents , Plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, or coupling agents. These elastomers, fillers, and additives can be used alone or in combination of two or more.

  In the present invention, it is necessary that the weight average fiber length of the molded product is 0.3 to 10 mm. By setting the weight average fiber length within this range, a molded product having a good balance between electromagnetic shielding properties and insulating properties can be obtained. As for the weight average fiber length of the carbon fiber in a molded article, 0.3-5 mm is more preferable, More preferably, it is 0.5-3 mm, More preferably, it is 0.8-2.0 mm.

  In order to obtain such a molded article, the molding material is, for example, (B) carbon fiber roving (A-1) made of a modified polyolefin resin and (A-2) an unmodified polyolefin resin (A) polyolefin Led to an impregnation die filled with a resin composition obtained by melting and kneading (C) an insulating inorganic filler and uniformly impregnating the resin composition between carbon fiber filaments, and then drawing through a nozzle, after cooling and solidifying There is a method obtained by pelletizing to a predetermined length.

  Preferably, (B) carbon fiber roving using a crosshead die (A) a polyolefin resin and (C) an insulation made of (A-1) a modified polyolefin resin and (A-2) an unmodified polyolefin resin This is a method of obtaining a molding material by impregnating and coating a resin composition obtained by melting and kneading a porous inorganic filler, cooling and solidifying, and pelletizing to a predetermined length.

  The pellet shape of the molding material is not particularly limited, but is usually in the range of 3 to 15 mm. If the pellet length is less than 3 mm, the fibers in the molded product may be shortened and the strength, impact, and electromagnetic wave shielding properties may be reduced. If the pellet length exceeds 15 mm, a biting failure in the molding machine may occur. Among them, the pellet length is preferably 3 to 12 mm, more preferably 5 to 10 mm.

  As the molded product of the present invention, any known injection molding machine such as an in-line screw type or a pre-plunger type can be used. In particular, injection press molding in which a predetermined amount of the mold is opened in advance and the mold clamping is completed after filling the resin into the mold is preferable from the viewpoints of reducing the filling pressure, preventing fiber breakage, and reducing warpage. In the injection press molding, the mold clamping may be started simultaneously with the start of resin filling, or the mold clamping may be started in the middle of resin filling.

The weight average fiber length of the (B) carbon fiber in the molded product was determined by ashing the molded product at 500 ° C. for 2 hours, taking out the (B) different carbon fiber in the sample, Place it in a beaker with 3 liters of water and use an ultrasonic cleaner to (B) uniformly disperse the carbon fiber in water, and (1) absorb 1 cc of the aqueous solution in which the carbon fiber is uniformly dispersed with a syringe with a tip diameter of 8 mm. It is a value obtained by the following equation by sampling a petri dish having a dent of 10 mm and drying it, taking a picture of (B) carbon fiber in the petri dish, measuring the length of about 1000 pieces.
Weight average fiber length = Σ (Mi ² × Ni) / Σ (Mi × Ni)
Mi: Fiber length (mm)
Ni: Number.

  The method for measuring the electromagnetic wave shielding property of the molded product is not particularly limited. For example, using an evaluation device manufactured by Microwave Factory, in accordance with the KEC method, in the region of the vicinity electric field of 10 (MHz) to 1 (GHz). It can be measured by the average shielding effect (dB). The higher the shielding effect, the better. For example, when the thickness of the molded product is 3 mm, it is preferably 15 dB or more. More preferably, it is 20 dB or more, and more preferably 30 dB or more.

  The method for measuring the insulation resistance value of the molded product is not particularly limited, but the insulation resistance value (kΩ) in the 500 V range is measured using an insulation resistance meter (Analog Megohm Hitester IR4042) manufactured by HIOKI. It is done. The higher the insulation resistance value, the better. However, for example, when the measurement span is 140 mm, it is preferably 10 kΩ or more. More preferably, it is 100 kΩ or more, and further preferably, 200 kΩ or more.

  As a molded article, it is suitable for automobile parts such as various modules such as an instrument panel, a door beam, an under cover, a lamp housing, a pedal housing, a radiator support, a spare tire cover, and a front end. Furthermore, home / office electrical product parts such as telephones, facsimiles, VTRs, copiers, televisions, microwave ovens, audio equipment, toiletries, laser discs (registered trademarks), refrigerators, air conditioners, and the like are also included. Further, there are a housing used for a personal computer, a mobile phone and the like, and a member for electric / electronic equipment represented by a keyboard support which is a member for supporting a keyboard inside the personal computer. The molded product of the present invention is excellent in balance between lightness, mechanical strength, insulation, and electromagnetic wave shielding, so that it can be used for portable electric / electronic device parts and electric vehicle storage containers such as battery cases and inverter cases. Particularly suitable for use as an ECU case.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Bending test of molded products]
In accordance with ASTM D790 (1997), a support span is set to 100 mm using a three-point bending test jig (indenter 10 mm, fulcrum 10 mm), and bending strength and bending elasticity are tested at a crosshead speed of 5.3 mm / min. The rate was measured. An “Instron (registered trademark)” universal testing machine 4201 type (manufactured by Instron) was used as a testing machine.

[Volume resistivity]
In accordance with JIS K 6271, volume low efficiency (Ω · cm) was measured by a four-terminal method shown in FIG. 1 using an ohmmeter HIOKI3541. The test piece was an ISO type tensile dumbbell test piece (4 mmt) obtained by injection molding (J110AD manufactured by Nippon Steel Works, cylinder temperature 230 ° C., mold temperature 60 ° C.). The obtained test piece was cut into a size of 80 × 10 mm (4 mmt) with a band saw, and the cut surface was smoothed with sandpaper having a roughness of No. 400 to obtain a test piece for measuring electrical resistance.

[Electromagnetic shielding]
Using an evaluation apparatus manufactured by Microwave Factory, the average shielding effect (dB) was measured in the region of the near electric field of 10 (MHz) to 1 (GHz) according to the KEC method. The shielding effect was calculated by the following formula (1). The test piece used was a 150 × 150 mm (3 mmt) square plate formed by injection molding.
_{SE = 20 × log10E 0 / E} X (1)
SE: Shielding effect (dB)
E ₀ : Spatial electric field strength when there is no shield material E _X : Spatial electric field strength when there is a shield material.

[Insulation resistance]
The insulation resistance value (kΩ) in the 500 V range of the ISO dumbbell test piece described above was measured with an electric circuit shown in FIG. 2 using an insulation resistance meter (Analog Megohm Hitester IR4042) manufactured by HIOKI. In addition, when conductivity was high and measurement was impossible, it was judged that insulation was insufficient.

[Weight average fiber length]
The center part of the dumbbell test piece prepared by the above method was cut into 20 × 10 mm (3 mmt) and subjected to ashing treatment at 500 ° C. for 2 hours, and the (B) carbon fiber in the sample was taken out. The taken out (B) carbon fiber was placed in a beaker together with 3 liters of water, and (B) the carbon fiber was uniformly dispersed in water using an ultrasonic cleaner. 1 cc of (B) an aqueous solution in which carbon fibers were uniformly dispersed was sucked with a dropper having a tip diameter of 8 mm, sampled in a petri dish having a 10 × 10 mm depression, and then dried. A photograph of (B) carbon fiber in the petri dish was taken, and the length of about 1000 pieces was measured to calculate the weight average fiber length. The calculation formula is as follows.
Weight average fiber length = Σ (Mi ² × Ni) / Σ (Mi × Ni)
Mi: Fiber length (mm)
Ni: Number.

Reference Example 1 (B-1) Carbon fiber 1
Spinning, firing treatment, and surface oxidation treatment were carried out from a copolymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total number of 24,000 single yarns. The characteristics of this continuous carbon fiber were as follows.
Single fiber diameter: 7μm
Mass per unit length: 1.6 g / m
Specific gravity: 1.8
Surface oxygen concentration ratio [O / C]: 0.03
Tensile strength: 4600 MPa
Tensile modulus: 220 GPa.

Here, the surface oxygen concentration ratio was determined according to the following procedure by X-ray photoelectron spectroscopy using the carbon fiber after the surface oxidation treatment. First, the carbon fiber bundle was cut to 20 mm, spread and arranged on a copper sample support, and then A1Kα1 and 2 were used as X-ray sources, and the inside of the sample chamber was kept at 1 × 10 ⁸ Torr. The kinetic energy value (KE) of the main peak of C _1s was adjusted to 1202 eV as a peak correction value associated with charging during measurement. C _1s peak area E. As a linear base line in the range of 1191 to 1205 eV. O _1s peak area E. As a linear base line in the range of 947 to 959 eV. The atomic ratio was calculated from the ratio of the O _1s peak area to the C _1s peak area using the sensitivity correction value unique to the apparatus. As an X-ray photoelectron spectroscopy apparatus, model ES-200 manufactured by Kokusai Electric Inc. was used, and the sensitivity correction value was set to 1.74.

  Further, a sizing agent mother liquor in which bisphenol F type epoxy (jER806: manufactured by Mitsubishi Chemical Corporation) is dissolved or dispersed in water so as to be 2% by mass is prepared, and (B-1) sizing agent is added to the carbon fiber by an immersion method. And dried at 230 ° C. The adhesion amount was 1.0% by mass.

Reference Example 2 (B-2) Carbon fiber 2
Spinning, firing treatment, and surface oxidation treatment were carried out from a copolymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total number of 24,000 single yarns. The characteristics of this continuous carbon fiber were as follows. Moreover, the sizing agent was provided similarly to the reference example 1.
Single fiber diameter: 7μm
Mass per unit length: 1.6 g / m
Specific gravity: 1.8
Surface oxygen concentration ratio [O / C]: 0.15
Tensile strength: 4600 MPa
Tensile modulus: 220 GPa.

Reference Example 3. (B-3) Carbon fiber 3
Spinning, firing treatment, and surface oxidation treatment were carried out from a copolymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total number of 24,000 single yarns. The characteristics of this continuous carbon fiber were as follows. Moreover, the sizing agent was not provided.
Single fiber diameter: 7μm
Mass per unit length: 1.6 g / m
Specific gravity: 1.8
Surface oxygen concentration ratio [O / C]: 0.03
Tensile strength: 4600 MPa
Tensile modulus: 220 GPa.

Reference Example 4 (A-1-1) Synthesis of modified homopolypropylene Homopolypropylene ("Prime Polypro" J137 manufactured by Prime Polymer Co., Ltd.) 99.6 parts by mass, maleic anhydride 0.4 parts by mass, and perhexi 25B (Nippon Yushi) as a polymerization initiator (Made by Co., Ltd.) 0.4 parts by mass was mixed and modified at a heating temperature of 160 ° C. for 2 hours to obtain (c-2) acid-modified polypropylene resin (acid content = 0.08 mmol equivalent). .

Reference Example 5 (A-1-2) Synthesis of modified block polypropylene Block polypropylene ("Prime Polypro" J707G manufactured by Prime Polymer Co., Ltd.) 99.6 parts by weight, maleic anhydride 0.5 parts by weight, and perhexi 25B (Nippon Yushi) as a polymerization initiator (Made by Co., Ltd.) 0.4 parts by mass was mixed and modified at a heating temperature of 160 ° C. for 2 hours to obtain (c-2) acid-modified polypropylene resin (acid content = 0.10 mmol equivalent). .

The (A) polyolefin resin and (C) insulating inorganic filler used in the examples and comparative examples are as follows.
(A-2-1): Homopolypropylene resin ("Prime Polypro" J137 manufactured by Prime Polymer Co., Ltd.)
(A-2-2): Block propylene resin ("Prime Polypro" J707G manufactured by Prime Polymer Co., Ltd.)
(C-1): Talc (Nippon Talc Co., Ltd. “fine talc” MICRO ACE P-4 particle size 4.3 μm)
(C-2): mica (manufactured by Yamaguchi Mica “Industrial wet pulverized mica powder” A-21S particle size 20 μm)
(C-3): Mica ("Industrial dry pulverized mica powder" B-82, particle size 180 μm, manufactured by Yamaguchi Mica)
(C-4): Glass beads ("General-purpose glass beads" GB301S particle size 50 μm, manufactured by Potters Barotini)

[Example 1]
First, the component (B-1) is opened while being heated to 200 ° C., and then the components (A-1-1), (A-2-1), and (C-1) are 80: 20: 1 (weight) The resin composition blended at a ratio of (Ratio) is put into a hopper of an extruder, extruded into an impregnation die heated to 230 ° C. in a melt-kneaded state at 230 ° C., and at the same time, (B− (B-1) is impregnated with a resin composition comprising components (A-1-1), (A-2-1) and (C-1) by continuously supplying 1) into the impregnation die. I let you. In addition, the discharge amount of an extruder and the supply amount of (B-1) were adjusted, and the continuous fiber reinforced resin strand whose content was (B-1) 8 wt% was obtained.

  Then, the continuous fiber reinforced resin group strand was cooled and solidified to 100 ° C. or lower, and cut into 6.0 mm length using a cutter to obtain long fiber pellets.

Next, using the J350EIII type injection molding machine manufactured by Nippon Steel Co., Ltd., the cylinder temperature: 220 ° C., the mold temperature: 60 ° C., and the long fiber pellets obtained were tested for characteristic evaluation. A piece (molded product) was formed. The obtained test piece was subjected to a characteristic evaluation test after being left in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and 50% RH for 24 hours. Next, the obtained molded product was evaluated according to the evaluation method described above. The evaluation results are collectively shown in Table 1.
As shown in Table 1, the evaluation result of this molded product was excellent in insulation and electromagnetic shielding properties.

[Examples 2 to 12 and Comparative Example 1]
Table 1 shows the resin composition comprising components (A-1-1), (A-2-1), and (C-1) to be charged into the hopper of the extruder, and (B-1) to be supplied to the impregnation die. Except for the ratios and components shown in Table 2, the samples were molded and evaluated in the same manner as in Example 1. Tables 1 and 2 show the evaluation results of the molded product.

  This example was superior to Comparative Example 1 in insulation and electromagnetic shielding properties.

[Comparative Example 2]
(B-3) was cut to 1/4 inch with a cartridge cutter. Next, Nippon Steel Works TEX-30α type twin screw extruder (screw diameter 30 mm, L / D = 32) was used, and components (A-1-1) and (A-2-2) were mixed into the main hopper. Then, the components (B-3) and (C-1) cut as described above are supplied from the downstream side hopper, sufficiently kneaded at a barrel temperature of 220 ° C. and a rotation speed of 150 rpm, and further a downstream vacuum vent More deaeration was performed. The feed was adjusted to the ratio shown in Table 2 using a weight feeder. The molten resin was discharged from a die port (diameter 5 mm), and the obtained strand was cooled and then cut with a cutter to obtain short fiber pellets.

  Next, the obtained short fiber pellet was molded in the same manner as in Example 1 and evaluated. The evaluation results of this molded product are shown in Table 2.

  Comparative Example 2 was inferior in electromagnetic shielding properties.

  The molded article of the present invention is a molded article that can produce a molded article that has both insulating properties and electromagnetic shielding properties and is excellent in mechanical properties, and is an electrical / electronic device, OA device, home appliance or automobile component, internal member, and It is suitably used for a housing or the like.

1. Test piece 2. Electrode 3. 3. Ammeter voltmeter

Claims (11)

(A-1) A modified polyolefin resin and (A-2) an unmodified polyolefin resin (A) 100 parts by weight of a polyolefin resin,
(B) A molded product obtained by molding a resin composition comprising 5 to 64 parts by weight of carbon fiber subjected to sizing treatment (C) 0.1 to 18 parts by weight of insulating inorganic filler, and (B) sizing treatment A molded product having a weight average fiber length of 0.3 to 10 mm. The resin composition is (A) 100% by weight of polyolefin resin, (A-1) more than 5% by weight of modified polyolefin resin and 99% by weight or less, (A-2) 1% by weight of unmodified polyolefin resin The molded product according to claim 1, wherein the molded product is less than 95% by weight. (A-1) The modified polyolefin resin has at least one functional group selected from a carboxyl group and a carboxylic anhydride group, The molded article according to any one of claims 1 and 2. (A-2) The unmodified polyolefin resin is homopolypropylene, and the molded product according to any one of claims 1 to 3. (C) The insulative inorganic filler is at least one selected from talc, mica, calcium carbonate, barium sulfate, titanium oxide, and glass filler, The molded article according to any one of claims 1 to 4, . (C) The average particle diameter of an insulating inorganic filler is 0.1-200 micrometers, The molded article in any one of Claims 1-5 characterized by the above-mentioned. The molded article according to any one of claims 1 to 6, wherein the molded article is an electrical component storage container. The O / C of carbon fiber is 0.1-0.3, The molded article in any one of Claims 1-7. (C) The insulating inorganic filler comprises (C-1) an insulating inorganic filler having an average particle diameter of 0.1 to 20 μm and (C-2) an insulating inorganic filler having an average particle diameter of 20 to 200 μm. The molded article according to any one of claims 1 to 8, wherein C-1) / (C-2) = 1/9 to 9/1. The molded article according to any one of claims 1 to 9, wherein (A-1) the modified polyolefin resin and / or (A-2) the unmodified polyolefin resin is block polypropylene. (B) The molded article according to any one of claims 1 to 10, wherein the carbon fiber has a weight average fiber length of 0.8 to 2.0 mm.

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