JP2002220786A - Carbon fiber bundle, resin composition, molding compound and molded product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber bundle having excellent electroconductivity (low surface resistivity and high electromagnetic shielding ability) and convergency, and to provide a resin composition, a molding compound and a molded product each using the same. SOLUTION: This carbon fiber bundle is characterized by being sized with a sizing agent that has the viscosity η1 at 200 deg.C and viscosity η2 at 300 deg.C each determined by a viscoelastometer manufactured by Rheometrics Far East Co. and meeting the relationships: η2<=500 and 1<=η1/η2<=50 and the thermogravimetric retention of >=85% at 300 deg.C when treated under heating from 50 deg.C to 400 deg.C at the rate of temperature up of 10 deg.C/min. The 2nd objective resin composition and the 3rd objective molding compound are each characterized by essentially comprising the above carbon fiber bundles and a thermoplastic resin. The other objective molded product is characterized by being obtained by the use of the above resin composition or molding compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber bundle, a resin composition, a molding material, and a molded article using the same, which are excellent in conductivity and moldability.

[0002]

2. Description of the Related Art Conventionally, a resin composition having desired conductivity has been proposed by blending a conductive material (for example, carbon fiber or the like) with a resin. On the other hand, in recent years, in order to obtain higher conductivity, various attempts have been made such as increasing the blending amount of the conductive material, using a plurality of conductive materials in combination, and treating the surface of the conductive material.

[0003] In general, when a carbon fiber is mixed and dispersed in various matrices to obtain a fiber reinforced material, in order to facilitate the handling of the carbon fiber and to enhance the workability in the mixing and dispersing steps, the carbon fiber must be prepared in advance. Is used.

However, especially when plastic is used as the matrix and glass fiber is used for mechanical reinforcement mainly from the economical point of view, the plastic and the glass fiber are both electrically non-conductive, and thus are obtained. Fiber reinforced materials also become electrically non-conductive. Fiber reinforced materials have fields where conductivity is required depending on the application in which they are used,
There is a demand for a fiber-reinforced material having excellent conductivity.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 61-23629, carbon fiber is used as a material for mechanical reinforcement of a fiber reinforced material. Attempts have been made to exploit sex. However, a significant improvement in conductivity cannot be obtained simply by mixing carbon fiber as a conductive substance in connection with other performance improvements, and a large amount of mixing is required. Therefore, if a large amount of carbon fiber is kneaded and used, there are problems such as an increase in the viscosity at the time of melting and an increase in cost, and the use thereof is limited. Examples of the technique for increasing the conductivity by using a conductive fiber and carbon black in combination include, for example, JP-A-59-217395, JP-B-3-44583, JP-A-6-240049, Tokuhei 8-19
It has been proposed in, for example, Japanese Patent Publication No. 256, Japanese Patent Application Laid-Open No. 9-87417, and the like.

However, any of these proposals causes problems such as a decrease in mechanical properties and a decrease in moldability (eg, fluidity during molding). Therefore, these proposals cannot simultaneously satisfy high conductivity and moldability. Did not.

[0007] Further, as a technique for increasing the conductivity by the surface treatment of the conductive material described above, a technique of coating the surface of various fibers with a metal by electroless plating or the like is given as an example. For example, JP-A-1-271439, JP-A-11-117
No. 179 discloses that metal-coated carbon fibers are used.

However, even with this proposal, the adhesion strength between the metal and the matrix resin is still insufficient,
Not only is there a problem in mechanical properties, but also the bonding strength between the reinforcing fiber and the metal is not sufficient, so that various fibers and the metal are peeled off, and the expected conductivity cannot be obtained.

In addition, a technique for attaching a specific sizing agent to the surface of carbon fiber is also mentioned as an example. For example, JP-A-3-26726 and JP-A-5-106164 disclose conductive techniques for sizing agent. Blending of conductive materials,
There is a description that by improving the conductivity of the sizing agent itself, the composition is made more conductive by making the sizing agent itself more conductive than the matrix resin.

[0010] However, even if the sizing agent itself is made highly conductive to a certain degree, the degree of improvement is very small in the case of a molded article using a conductive material having a significantly higher conductivity than the resin which is originally an insulator. However, the conductivity was not satisfactory.

That is, according to the above proposals, a carbon fiber bundle which can exhibit a high level of conductivity and further satisfy moldability such as convergence, a molded article and a molding material obtained therefrom, and a resin composition using the same Could not get.

[0012]

SUMMARY OF THE INVENTION In view of the background of the prior art, the present invention provides an excellent carbon fiber which exhibits excellent conductivity, that is, a low surface resistance, a high electromagnetic wave shielding property, and excellent convergence. It is an object to provide a bundle, a resin composition, a molding material, and a molded article using the same.

[0013]

The present invention employs the following means in order to solve the above-mentioned problems. That is, in the carbon fiber bundle of the present invention, the viscosities η1 and η2 defined below are η2 ≦ 500 and 1 ≦ η1.
/ η2 ≦ 500, and a sizing agent having a thermal weight retention of 85% or more as defined below is attached to the fiber surface.

Sizing agent viscosity η1: A sizing agent in an absolutely dry state, expressed as a viscosity at 200 ° C. when measured under the following conditions using a viscoelasticity measuring device (RDA-II) manufactured by Rheometrics Far East Co., Ltd. Viscosity η2 of sizing agent: A sizing agent in a completely dry state,
Using a rheometric spur yeast viscoelasticity measuring device (RDA-II), 3
Measured in terms of viscosity at 00 ° C. Measurement conditions: 2 g of a sizing agent in a completely dry state with a diameter of 40 mm
The gap between the gaps was set to 1 mm using a parallel plate of 3. The parallel plate twisting speed was 3.14 rad / sec.
Heat treatment to 0 ° C. Thermogravimetric retention of sizing agent: Absolutely dried sizing agent is heated from 50 ° C. to 4 ° C. in an air atmosphere at a rate of 10 ° C./min.
Thermogravimetric retention at 300 ° C. when heated to 00 ° C. The resin composition of the present invention is characterized by containing at least the carbon fiber bundle and the thermoplastic resin. The molded article is characterized by being composed of such a resin composition or a molding material.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention has been made to solve the above-mentioned problems, namely,
We investigated the molding material having excellent conductivity (low surface resistance, high electromagnetic wave shielding property) and moldability (bundling property) and molded products using it, and attached a sizing agent satisfying specific conditions. When a carbon fiber bundle was created, it was determined that such a problem could be solved at once.

The sizing agent of the present invention refers to one that imparts a desired function to a fiber bundle, such as bundling of a fiber bundle to be adhered and control of affinity with a matrix resin used in forming a molded article. In the present invention, what is attached to the surface of the carbon fiber for the purpose of solving the problems of the present invention is generally referred to as a sizing agent.

The sizing agent used in the present invention has the following viscosities η1 and η2 satisfying η2 ≦ 500 and 1 ≦ η1 /
η2 ≦ 500, and the following thermogravimetric retention is 85%
The above is the feature.

Sizing agent viscosity η1: A sizing agent in an absolutely dry state, expressed as a viscosity at 200 ° C. when measured under the following conditions using a viscoelasticity measuring device (RDA-II) manufactured by Rheometrics Far East Co., Ltd. Sizing agent viscosity η2: A sizing agent in a completely dry state was measured using a viscoelasticity measuring device (R
DA-II) and 300 when measured under the following conditions:
Measured in terms of viscosity at 0 ° C. Measurement conditions: 2 g of a sizing agent in a completely dry state having a diameter of 40 mm
Using a parallel plate, the gap was set to 1 mm, and the parallel plate twisting speed was 3.14 rad / sec.
From 150 ° C to 3 at a heating rate of 10 ° C / min in air atmosphere
Heat treatment up to 50 ° C. Thermogravimetric retention of sizing agent: Absolutely dried sizing agent is heated from 50 ° C. to 4 ° C. at a rate of 10 ° C./min in an air atmosphere.
Thermogravimetric retention at 300 ° C. when heat-treated to 00 ° C. Here, viscosities η1 and η2 of the sizing agent are η2 ≦ 500.
And 1 ≦ η1 / η2 ≦ 500. The reason for this is that if η2 is greater than 500, it is difficult to achieve uniform dispersion of carbon fibers due to its viscosity during molding, resulting in poor conductivity. Therefore, η2 ≦ 450 is preferable, and η2 ≦ 400 is more preferable. Further, when η1 / η2 is less than 1 (that is, the viscosity increases when heat of 200 ° C. or more is applied), the sizing agent continues to increase in viscosity during molding, and the carbon fiber in the molded article of carbon fiber Uniform dispersion is hindered, and furthermore, the carbon fibers are physically in contact with each other in the molded article, thereby hindering the formation of a conductive path, and as a result, the conductivity of the molded article is deteriorated. Also, η1 / η2 is larger than 500, that is, η1 is extremely high (> 25000).
Or, η2 is extremely low, but in the former case, the viscosity of carbon fibers is high immediately after the start of molding (immediately after the start of heating), so that the dispersion of carbon fibers is relatively slow as compared with those having low η1. And it is difficult to achieve uniform dispersion. In the latter case, there is a possibility that the sizing agent is thermally decomposed, which may cause voids in the molded product and may deteriorate the conductivity.

From such a meaning, the thermogravimetric retention of the sizing agent is also specified, but if the thermogravimetric retention is 85% or less, voids in the molded article due to the generation of pyrolysis gas may occur. As a result, the conductivity may be degraded.

As described above, the present invention has found that the object of the present invention can be solved by attaching a sizing agent having a viscosity at a specific temperature in a specific range to a surface of a carbon fiber. .

That is, since the sizing agent of the present invention has an appropriate fluidity as described above, it is possible to achieve a uniform dispersion of carbon fibers and not to cause significant decomposition even at a molding temperature. Further, the object of the present invention can be solved.

The sizing agent of the present invention may be a thermoplastic resin. A thermoplastic resin is considered to be effective because the viscosity decreases as the temperature increases, and it is easily expected that 1 ≦ η1 / η2.

It is effective to lower the surface tension in order to make the attachment of the sizing agent to the carbon fiber uniform, but for that purpose, a surfactant, an organic solvent, a lubricant, a defoaming agent, etc. Can be applied. As a method of applying the treating agent, a sizing agent is attached after applying them to the carbon fiber in advance, or a solution of the treating agent is blended with a sizing agent solution and attached together with the sizing agent. Can be.

The sizing agent of the present invention is prepared by contacting or dipping the carbon fiber in the state of a solution of a solvent solution, an aqueous solution, an aqueous emulsion or a mixture thereof, followed by drying the water and / or the solvent. Although it may adhere to carbon fibers, it is preferable to adhere to elementary fibers using an aqueous solution or an aqueous emulsion solution containing no solvent from the viewpoint of a working environment. Note that the amount of the sizing agent attached can be adjusted by the concentration of the solution.

The sizing agent of the present invention is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and further preferably 0.1 to 3% by weight, based on carbon fibers.
%, Particularly preferably in the range of 0.2 to 2% by weight. If the amount is less than this, it is difficult to obtain a desired effect. On the other hand, if it is more than this, it becomes difficult to obtain excellent conductivity.

The sizing agent in the present invention is preferably at least 5% by weight, more preferably at least 30% by weight, further preferably at least 50% by weight, particularly preferably at least 50% by weight, based on the total amount of all the deposits attached to the carbon fibers. Is preferably in the range of 70% by weight or more. If the amount is less than this, the effect of the present invention may not be sufficiently exhibited.

The carbon fibers of the present invention include, for example, polyacrylonitrile (PAN), pitch (isotropic, mesophase, etc.), cellulose (viscose rayon,
Carbon fiber and graphite fiber made from cellulose acetate) and gas phase growth (hydrocarbon etc.) systems, and even metal such as nickel, ytterbium, gold, silver, copper, etc. by plating (electrolysis, Electroless), CVD method, PVD
A metal-coated carbon fiber formed by coating at least one layer by a method, an ion plating method, a vapor deposition method, or the like, or a material formed by blending two or more of these can be used. In addition, a blend of such a carbon fiber and another reinforcing fiber such as a glass fiber or an aramid fiber can also be used in the present invention. As such carbon fibers, PAN-based carbon fibers having excellent balance between mechanical properties such as strength and elastic modulus and price and / or
Alternatively, a vapor grown carbon fiber having high conductivity is preferably used.

These carbon fibers have an average single fiber diameter of preferably 0.01 to 20 μm, more preferably 1 to 16 μm.
μm, more preferably 2 to 13 μm, particularly preferably 4 to 11 μm. When the average single fiber diameter is less than 0.01 μm, not only is it difficult to produce carbon fibers, but also the mechanical properties may be poor. Further, when a resin composition is obtained using carbon fibers, it becomes difficult to impregnate the resin into the carbon fiber bundle, which may cause problems such as poor dispersibility of the carbon fibers in the molded product. On the other hand, if the average single fiber diameter exceeds 20 μm, the mechanical properties of the carbon fiber are inferior, and the desired conductive effect or reinforcing effect may not be obtained.

The continuous fiber (filament) type carbon fiber bundle of the present invention has a single fiber number of 4000 to 350.
It is preferable that the bundle is bound in the range of 000 pieces. If the number of single fibers is less than 4000, the productivity of the carbon fiber itself is poor, which is not preferable. The number of single fibers is 350
If the number is more than 000, not only is the carbon fiber bundle inferior in handleability, but the molded product obtained using those carbon fiber bundles may be inferior in conductivity and mechanical properties, and the effect of the present invention can be effectively reduced. It is not preferable because it cannot be expressed in a specific manner. The number of single fibers is more preferably 6,000 to 100,000, further preferably 12,000 to 75,000, particularly preferably 24,000 to 48,000.

The chopped carbon fiber of the present invention is obtained by cutting the above continuous carbon fiber bundle into a range of preferably 1 to 26 mm, more preferably 2 to 13 mm, particularly preferably 3 to 10 mm. When the chopped carbon fiber is less than 1 mm, the carbon fiber bundled at the time of cutting becomes easy to spread, and fluffs and pills are generated. If it exceeds 26 mm, when kneading with the resin, the extruder is likely to be clogged or bridged at the extruder supply port (hopper, supply pipe, etc.), which may cause a problem in the supply to the extruder.

Here, the method of cutting the continuous carbon fiber bundle is not particularly limited, and the sizing agent, and in some cases, the treating agent (1) and the treating agent (2) may be used in the form of an aqueous solution or an aqueous emulsion, a solvent solution, or a mixture thereof. After the liquid is adhered to and imparted to the carbon fiber, the water (or solvent) may be dried and then cut, or may be cut before drying and then dried. In order to cut the convergence higher,
After the above-mentioned aqueous solution, water emulsion, solvent solution or mixture thereof is attached and applied, cutting is performed while the water content (or solvent content) is in the range of 3 to 80%, and then the water content (or Alternatively, drying is preferably performed so that the solvent content is less than 3%. The preferred water content (or solvent content) before cutting is in the range of 10-70% by weight, more preferably 15-60% by weight.

The water content (or solvent content) is defined as the weight of a product obtained by drying for 2 hours or more (preferably 4 hours or more) in a circulating atmosphere at the boiling point of water or the solvent + 40 ° C., by the weight before drying. Refers to the value obtained by converting the value
The upper limit of the weight of the measurement object was 30 g.

The resin composition of the present invention comprises at least the above-mentioned component [A] which is a bundle of carbon fibers and chopped carbon fibers, and component [B] which is a thermoplastic resin described later.

The constituent element [B] of the present invention is a thermoplastic resin which is excellent in impact strength of the obtained molded product and can be subjected to press molding or injection molding with high molding efficiency.

Examples of the thermoplastic resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), and polyethylene naphthalate (PE).
N), polyesters such as liquid crystal polyesters, polyolefins such as polyethylene (PE), polypropylene (PP) and polybutylene, styrene resins, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), Polymethylene methacrylate (P
MMA), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyphenylene ether (PP
E), polyimide (PI), polyamideimide (PA
I), polyetherimide (PEI), polysulfone (PSU), polyethersulfone, polyketone (P
K), polyether ketone (PEK), polyether ether ketone (PEEK), polyarylate (PA
R), polyether nitrile (PEN), phenol (novolak type, etc.) phenoxy resin, fluorine resin, and also polystyrene, polyolefin, polyurethane, saturated polyester, polyamide, polybutadiene, polyisoprene, fluorine, etc. It may be a thermoplastic elastomer or the like, a copolymer or a modified product thereof, or a resin in which two or more kinds are blended. Further, in order to further improve the impact resistance, a resin obtained by adding another elastomer or a rubber component to the thermoplastic resin may be used.

It is preferable that the amorphous resin contains at least one of a styrene resin, a polycarbonate resin and a polyphenylene ether resin.

In the present invention, preferred styrene resins include styrene polymers such as PS (polystyrene),
Rubber-reinforced styrene-based polymers such as HIPS (high impact polystyrene), styrene-based copolymers such as AS (acrylonitrile / styrene copolymer), AES (acrylonitrile / ethylene-propylene / non-conjugated diene rubber / styrene copolymer), ABS (acrylonitrile / butadiene / styrene copolymer), MBS (methyl methacrylate /
Rubber-reinforced (co) polymers such as butadiene / styrene copolymer) and ASA (acrylonitrile / styrene / acrylic rubber copolymer). Among them, styrene-based polymers such as PS (polystyrene), and AS ( Styrene-based copolymers such as acrylonitrile / styrene copolymer),
ABS (acrylonitrile / butadiene / styrene copolymer) and ASA (acrylonitrile / styrene / acrylic rubber copolymer) are preferred.

The polycarbonate resin (hereinafter referred to as PC
The resin has a viscosity average molecular weight of 10,000 to 10,000 obtained by reacting an aromatic dihydric phenol compound with phosgene or a carbonic acid diester.
An aromatic homo or copolycarbonate resin in the range of 00 is used.

As the polyphenylene ether resin (hereinafter referred to as PPE resin), chloroform
A polymer having an intrinsic viscosity of 0.01 to 0.8 dl / g measured at 0 ° C. is preferably used. Specifically, poly (2,
6-dimethyl-1,4-phenylene) ether, 2,6
-Dimethylphenol / 2,4,6-trimethylphenol copolymer, 2,6-dimethylphenol / 2,3
A 6-triethylphenol copolymer or the like can be used.

These amorphous resins may be used in combination of two or more kinds. Specifically, ABS resin, ASA resin or a combination of AS resin and PC resin, PPE resin and P resin
A combination of an S resin or a HIPS resin, a combination of a PC resin and a PS resin or a HIPS resin, or the like can be preferably employed.

When combined with the sizing agent of the present invention,
The thermoplastic resin that maximizes the effects of the present invention is at least one selected from styrene resins, polycarbonate resins, and polyphenylene ether resins.

The resin composition of the present invention comprises the resin composition 10
For 0% by weight, component [A] is preferably 1 to 8
5% by weight, more preferably 5 to 50% by weight, still more preferably 8 to 40% by weight, particularly preferably 15 to 30% by weight
It is good to be in the range.

If the content of the component [A] is less than 1% by weight, it is difficult to obtain a desired conductivity, and if it exceeds 85% by weight, the fluidity during molding is reduced and the moldability is poor. The resin composition of the present invention may further include a filler, a conductivity-imparting material, a flame retardant, a flame retardant aid, a pigment, a dye, a lubricant, a release agent, a compatibilizer, a dispersant, and a crystal nucleus, depending on the purpose. Agent, plasticizer, heat stabilizer,
Antioxidant, anti-coloring agent, ultraviolet absorber, fluidity modifier, foaming agent, antibacterial agent, vibration damper, deodorant, slidability modifier,
Any additive of the antistatic agent can be used alone or as a blend of two or more.

The above-mentioned filler is added to the resin composition of the present invention.
When compounding a conductivity-imparting material, a flame retardant, or the like, the compound may be kneaded with a resin or the like in advance using an extruder, or may be compounded separately from the resin composition by dry blending or coating. Further, they may be mixed in advance during the polymerization of the resin.

The resin composition of the present invention can be produced by, for example, injection molding (injection compression molding, gas assist injection molding, insert molding, supercritical fluid fine foam molding, etc.), blow molding, rotational molding, extrusion molding, press molding, transfer molding. It is formed by a molding method such as filament winding molding, and the most desirable molding method is preferably injection molding with high productivity. As the form of the molding material used for such molding, pellets, stampable sheets, prepregs and the like can be used, and the most desirable molding material is a pellet used for injection molding.

The above-mentioned pellet generally refers to a pellet obtained by kneading a desired amount of resin and fiber chopped yarn or continuous fiber in an extruder, extruding and pelletizing. In the above-mentioned pellet, the fiber length in the pellet is shorter than the length of the pellet in the longitudinal direction, but the pellet in the present invention includes a long fiber pellet.
Long-fiber pellets, as shown in JP-B-63-37694, are such that fibers are arranged substantially parallel to the longitudinal direction of the pellet, and the fiber length in the pellet is equal to or longer than the pellet length. Points to something. In this case, the resin may be impregnated in the fiber bundle or coated on the fiber bundle. Particularly, in the case of a long fiber pellet coated with a resin, the fiber bundle may be impregnated in advance with a resin having the same viscosity as the coated fiber or a resin having a lower viscosity (or lower molecular weight) than the coated resin.

Since the molded article of the present invention can impart excellent conductivity, it is preferably used as a molded article having a surface resistance of 1 × 10 ⁶ Ω / □ or less. If the molded product has a surface resistance value of more than 1 × 10 ⁶ Ω / □, it is difficult to adapt to applications such as an antistatic material and the use may be limited. The molded article obtained from the resin composition of the present invention has a surface resistance value of preferably 1 × 10 ⁵ Ω.
/ □ or less is preferred. Preferably 1 × 10 ⁴ Ω /
□ or less, more preferably 1 × 10 ³ Ω / □ or less, particularly preferably 1 × 10 ² Ω / □ or less.

In the present invention, a test piece for measuring a surface resistance value is used to minimize the influence of carbon fiber orientation.
Square molded product (length 8)
0 mm x width 80 mm x thickness 3 mm). The test piece is coated with a conductive paste in a range of 20 mm width × 20 mm length at four locations shown in FIG. 1, where adjacent coating portions are 20 mm wide in the width direction and 2 mm long in the length direction.
It has a distance of 0 mm and is not coated with a conductive paste surrounded by four coating portions. The width is 20 mm x the length is 20 m.
The coating is performed such that the center point in the range of m is the center point of the molded product. The test piece to which this conductive paste was applied was subjected to measurement in a completely dry state (moisture percentage: 0.05% or less). Here, at the time of measurement, the average value of the electric resistance values between the range (1)-(2) and (3)-(4) where the conductive paste was applied was defined as the surface resistance value in the length direction, and (1) )-(3),
The average value of the electrical resistance values between (2) and (4) was defined as the surface resistance value in the width direction, and the average value in the length direction and the width direction was defined as the surface resistance value of the test piece (unit: Ω / □). ). Note that a digital multimeter (R6581 manufactured by Advantest) was used for measuring the electric resistance value.

Further, since the molded article of the present invention can impart excellent conductivity, it is preferably used as a molded article having an electromagnetic wave shielding property of 1 dB or more at 1 GHz. As a molded product, its electromagnetic wave shielding property is 15
If it is less than dB, it is difficult to apply to applications such as electromagnetic wave shielding materials and the use may be limited. Preferably 1G
17 Hz or more, more preferably 20 dB or more, even more preferably 23 dB or more, especially 27 dB in Hz.
The above is preferred.

In the present invention, the test piece for measuring the electromagnetic wave shielding property is 150 mm wide × 150 mm long × 1 thickness.
It measures with a square flat plate of mm. Here, in order to reflect the value in the actual molded product as much as possible, the width is 155 m.
mx 190mm long x 1mm thick, 12m high
A housing having an m standing wall is formed by eight pin gates having a diameter of 1.5 mm, and a square flat plate having a width of 150 mm, a length of 150 mm and a thickness of 1 mm is cut out from the center.

The layout of the pin gates is eight in FIG. 2, and the distance between the pin gates (8) and (9) is 10
5 mm, the distance between pin gates (10) and (12), the distance between (13) and (15) is 130 mm, the distance between pin gates (11) and (14) is 95 mm, and the distance between pin gates (10) and (13), (12) The distance between (15) and (15) is 115 mm. A conductive paste was applied to the entire periphery of the cut-out test piece in the plate thickness plane, and subjected to measurement in a completely dry state (water content of 0.05% or less) (unit: dB).

The measurement was performed by the Advantest method.
The shield box uses TR-17301A (manufactured by Advantest) and the spectrum analyzer uses R3361B (manufactured by Advantest). The frequency is 10 MHz to 1 GHz.
It was measured in the range of z.

In order to simultaneously satisfy the conductivity of the molded article and the reduction of the raw material cost in the molded article which requires conductivity such as the above-mentioned surface resistance value and electromagnetic wave shielding property, the resin component [A Is preferred to be low, but in that case, the conductivity is reduced. Even in such a case, since high conductivity is achieved by the above-described conductivity-imparting material such as carbon black, it is preferable to add a conductivity-imparting material when particularly excellent conductivity is required.

The molded article of the present invention may be used for electronic / electric equipment, OA equipment and precision equipment, automobile parts, housing parts, casing parts, etc., for which excellent conductivity is required. Is a preferable example, and a housing of a portable electronic / electric device, which is particularly required to be lightweight and has a high electromagnetic wave shielding property, is particularly preferable. More specifically, large displays, notebook computers, mobile phones, P
HS, PDA (portable information terminal such as electronic organizer), video camera, video camera, digital still camera, portable radio cassette player, housing of inverter and the like.

Also, since it has excellent conductivity, it can be provided with a charge / discharge prevention property by adding a small amount of the component [A], and a member requiring such properties, for example, an IC tray It is also useful for application to baskets for transporting silicon wafers.

[0056]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the present invention, and all changes and implementations without departing from the spirit of the preceding and following descriptions are possible. It is included in the technical scope of the invention.

The evaluation items and methods for the chopped carbon fibers obtained by cutting the carbon fiber bundle of the present invention are described below. (1) Bundleability After 100 g of chopped carbon fiber was placed in a 500 ml measuring cylinder, the measuring cylinder was lightly vibrated 10 times, and the volume at that time was divided by the input weight to represent the value (unit: g / cm3). ).

A resin composition using the carbon fiber bundle of the present invention,
Evaluation items and methods for molding materials and molded articles are described below. (2) Surface resistance value First, a test piece having a width of 80 mm x a length of 80 mm x a thickness of 3 mm was injection molded. Then, 20m wide at four places shown in FIG.
A conductive paste (Doitite manufactured by Fujikura Kasei Co., Ltd.) is applied in a range of mx 20 mm in length, and the conductive paste is sufficiently dried, and then completely dried (water content: 0.05% or less).
Was used for measurement. At the time of measurement, the average value of the electric resistance between the range (1)-(2) and the range (3)-(4) where the conductive paste was applied was defined as the surface resistance in the length direction, and (1)-
The average value of the electrical resistance values between (3) and (2)-(4) was defined as the surface resistance value in the width direction, and the average value in the length direction and the width direction was defined as the surface resistance value of the test piece ( The unit is logΩ
/ □). Note that a digital multimeter (R6581 manufactured by Advantest) was used for measuring the electric resistance value.
In this measurement, 10 samples were measured, and the average value thereof was used. (3) Electromagnetic Wave Shielding Property First, a housing having a projection surface of 155 mm in width × 190 mm in length × 1 mm in thickness and a standing wall of 12 mm in height is formed with eight pin gates of 1.5 mm in diameter and 150 mm in width from the center thereof. A square flat plate having a length of 150 mm and a thickness of 1 mm was cut out. Next, a conductive paste (Doitite manufactured by Fujikura Kasei Co., Ltd.) was applied to the entire periphery of the plate thickness side of the cut-out test piece shown in FIG.
After the conductive paste was sufficiently dried, it was subjected to measurement (unit: dB) in a completely dry state (moisture ratio: 0.05% or less).
The measurement was performed by the Advantest method. The shield box was TR-17301A (manufactured by Advantest), and the spectrum analyzer was R3361B (manufactured by Advantest).
And measured in the frequency range of 10 MHz to 1 GHz. In this measurement, five samples were measured, and the average value at 1 GHz was used.

Examples 1 to 3 and Comparative Examples 1 to 3 Continuous carbon fiber bundles were immersed in an aqueous solution or aqueous emulsion of a sizing agent adjusted to a desired concentration while applying tension, and an aqueous solution or aqueous emulsion of a sizing agent was applied. The carbon fiber bundle in a state where each filament of the carbon fiber bundle was wet was cut into 6 mm with a cartridge cutter.
Next, the cut carbon fiber bundle is heated with hot air at 120 ° C. for 3 hours.
Dried for 0 minutes, chopped carbon fiber (component [A])
Get. The amount of the sizing agent adhered to the obtained chopped carbon fiber was 2% by weight, assuming that the chopped carbon fiber was 100% by weight.

Here, the amount of the sizing agent attached to the carbon fibers was measured by a thermal decomposition method. Specifically, the weight W1 of the carbon fiber to which the sizing agent, which has been dried to a moisture content of 0.05% or less, is attached, and the carbon fiber is heated at 450 ° C. for 15 minutes in a nitrogen atmosphere. 25 ° C
(W1-W2) x 1 using the weight W2 after cooling for 15 minutes and humidity control at 25C for 10 minutes in an atmosphere of 50% humidity.
Calculated from 00 / W1 (unit is% by weight).

A desired amount of the component [A] (chopped carbon fiber) and the polycarbonate resin as the component [B] were kneaded with a twin-screw extruder, and cut into 5 mm with a cutter.
A pellet was obtained.

After the obtained pellets were dried in vacuum at 80 ° C. for 5 hours or more, they were injection-molded, and
Each test described in (3) was used. Table 1 shows the evaluation results.

[0063]

[Table 1]

The following carbon fibers and sizing agents were used. <Carbon fiber> Dry-wet spinning PAN system, number of single fibers = 240
00, average single fiber diameter = 7 μm <Sizing agent> S1: Water-soluble aromatic polyester resin S2: Water-soluble aromatic polyester resin S3: Water-soluble polyamide resin S4: Epoxy resin [Ep828 and Ep1 manufactured by Yuka Shell Co., Ltd.]
Mixed epoxy resin obtained by dispersing an equivalent mixture with 001 in water using an emulsifier] S5: Water-soluble aromatic polyester resin S6: Water-soluble polyurethane resin [Polyester copolymer] From the results in Table 1, the following is clear. . 1. Effect of sizing agent Compared with Comparative Examples 1 to 3 using chopped carbon fibers to which a sizing agent that does not satisfy the conditions specified by the present invention is adhered, a sizing agent that satisfies the conditions specified by the present invention is adhered. Examples 1 to 3 using chopped carbon fibers
It can be seen from the result that a molded article excellent in conductivity can be obtained because the surface resistance can be lowered and the electromagnetic wave shielding property can be increased.

[0065]

According to the carbon fiber bundle of the present invention, it is possible to provide a carbon fiber bundle having excellent conductivity (low surface resistance value, high electromagnetic wave shielding property). A resin composition, a molding material, and a molded article having conductivity can be provided. That is, particularly suitable for a wide range of industrial fields requiring the above characteristics, including molded products such as members for electric / electronic devices, OA devices and precision devices, members for automobiles and members for housings and casings. Can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a test piece for measuring a surface resistance value according to the present invention.

FIG. 2 is a perspective view of a housing for measuring electromagnetic shielding properties according to the present invention.

[Explanation of symbols]

 1: conductive paste application range (1) 2: conductive paste application range (2) 3: conductive paste application range (3) 4: conductive paste application range (4) 5: test piece for measuring surface resistance value 6: Position for cutting out the test piece for measuring electromagnetic wave shielding property 7: Housing for measuring electromagnetic wave property 8: Pin gate (8) 9: Pin gate (9) 10: Pin gate (10) 11: Pin gate (11) 12: Pin gate (12) 13: Pin gate (13) 14: Pin gate (14) 15: Pin gate (15) 16: Test piece for measuring electromagnetic shielding properties

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D06M 101: 40 D06M 15/507 Z F-term (Reference) 4F072 AA02 AA08 AB10 AB22 AC05 AD41 AG05 AK15 AL11 AL16 AL17 4L033 AA09 AC06 AC12 BA00 BA99

Claims (12)

[Claims] 1. The viscosities η1 and η2 defined below are defined as η
2 ≦ 500, and 1 ≦ η1 / η2 ≦ 500,
A carbon fiber bundle characterized in that a sizing agent having a thermogravimetric retention of 85% or more as defined below is attached to the fiber surface. Sizing agent viscosity η1: A sizing agent in a completely dry state is converted into a viscoelasticity measuring device (R
DA-II) and 200 when measured under the following conditions:
The viscosity expressed in terms of viscosity at ° C. Viscosity of the sizing agent η2:
Using a rheometric spur yeast viscoelasticity measuring device (RDA-II), 3
Measured in terms of viscosity at 00 ° C. Measurement conditions: 2 g of a sizing agent in a completely dry state with a diameter of 40 mm
The gap between the gaps was set to 1 mm using a parallel plate of 3. The parallel plate twisting speed was 3.14 rad / sec.
Heat treatment to 0 ° C. Thermogravimetric retention of sizing agent: Absolutely dried sizing agent is heated from 50 ° C. to 4 ° C. in an air atmosphere at a rate of 10 ° C./min.
Thermogravimetric retention at 300 ° C when heat-treated to 00 ° C 2. The carbon fiber bundle has an average single fiber diameter of 0.5.
In the range of 01 to 20 μm and the number of single fibers is 40
The carbon fiber bundle according to claim 1, wherein the number of the carbon fiber bundles ranges from 00 to 350,000. 3. The carbon fiber bundle according to claim 1, wherein the sizing agent contains a thermoplastic resin. 4. The carbon fiber bundle according to claim 1, wherein the sizing agent is contained in an amount of 50% by weight or more of the attached matter of the carbon fiber bundle. 5. The carbon fiber according to claim 1, wherein the sizing agent is attached to the carbon fiber in an amount of 0.01 to 20% by weight.
5. The carbon fiber bundle according to 3 or 4. 6. The carbon fiber bundle is a chopped carbon fiber cut in a range of 1 to 26 mm.
The carbon fiber bundle according to any one of the above. 7. A resin composition comprising at least the following components [A] and [B]. [A]: the carbon fiber bundle according to any one of claims 1 to 6 [B]: a thermoplastic resin 8. The resin composition according to claim 7, wherein the component [A] is contained in an amount of 8 to 40% by weight in 100% by weight of the resin composition. 9. A molding material, wherein the resin composition according to claim 7 has a form of a pellet. 10. A molded article comprising the resin composition according to claim 7 or the molding material according to claim 9. 11. The molded article according to claim 10, wherein the molded article is injection molded. 12. The molded article is a member for electric / electronic equipment,
The molded product according to claim 10, which is a member selected from a member for OA equipment, a member for precision equipment, a member for automobile, and a member for housing.