JP2002338802A - Conductive resin composition, and molding material or molded item prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-specific-gravity conductive resin composition excellent in electric conductivity and a molding material and a molded item both comprising the composition. SOLUTION: This conductive resin composition at least comprises [A] discontinuous conductive fibers, [B] a polyvinyl alcohol resin, and [C] a polyamide resin, the contents of ingredients [A] and [B] being 1-50 wt.% and 0.01-6 wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin composition capable of obtaining excellent conductivity at a low specific gravity, and to a molding material or a molded article comprising the same.

[0002]

2. Description of the Related Art In recent years, high electrical conductivity has been required for molded articles of electric and electronic devices and their auxiliary materials. Further, in portable devices represented by portable information terminals, low specific gravity (light weight) is also required for convenience in carrying.

Conventionally, it has been proposed that a resin composition having desired conductivity can be obtained by blending an inorganic conductive material (carbon, metal, etc.) with a resin. Specifically, attempts have been made to increase the blending amount of the conductive material, but there has been a problem that the specific gravity is essentially increased, and the demand for a low specific gravity (light weight) cannot be satisfied. .

[0004] On the other hand, in order to obtain high conductivity while minimizing the amount of the inorganic conductive material to be compounded, attempts have been made to devise the resin composition of the resin composition.

As an example of the technique for increasing the conductivity by devising the resin composition of the resin composition, a technique of using a plurality of resins in combination is disclosed in, for example, JP-A-50-32240.
JP, JP-A-62-4747, JP-A-63-2947
JP 07855, JP-A-1-263156, JP-A-2-113068, JP-A-5-287143
In Japanese Unexamined Patent Application Publication No. H8-12768, the conductive material is unevenly distributed in one of the matrix resins having a sea / island structure, a sea / sea structure, a three-dimensional network structure, or the like. There is a description that the amount of an apparent conductive material can be increased to achieve high conductivity. However, in any of these proposals, it is necessary to make the conductive material unevenly distributed in one of the matrix resins, and there is a problem that the production of the molding material is limited. In addition, one of the resins must be blended in a relatively large amount, which causes problems such as non-uniformity of the resin composition and microscopic unevenness of conductivity.

That is, according to the above-mentioned proposals, it has not been possible to obtain a molded body that satisfies the requirement for a low specific gravity (light weight) of the molded body and can exhibit excellent conductivity.

[0007]

SUMMARY OF THE INVENTION In view of the background of the prior art, the present invention does not provide a conductive resin composition, a molding material, and a molded article made of the same, which can obtain excellent conductivity at a low specific gravity. It is assumed that.

[0008]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the conductive resin composition of the present invention, at least,
A conductive resin composition comprising the following components [A], [B] and [C], and the weight ratio of the component [A] is 1 to 50% by weight; The conductive resin composition is characterized in that the component [B] is 0.01 to 6% by weight.

Component [A]: discontinuous conductive fiber.

Component [B]: polyvinyl alcohol resin.

Component [C]: polyamide resin.

[0012] The molding material of the present invention is characterized by having such a conductive resin composition.

Further, the molded article of the present invention is characterized by being formed by molding such a conductive resin composition or molding material.

[0014]

Embodiments of the present invention will be described below.

The conductive resin composition of the present invention is a conductive resin composition having at least the following constituents [A], [B] and [C], and has a weight ratio of It is necessary that the content of the component [A] is 1 to 50% by weight, and the content of the component [B] is 0.01 to 6% by weight.

Component [A]: discontinuous conductive fiber.

Component [B]: polyvinyl alcohol resin.

Component [C]: polyamide resin.

Although the details of the mechanism for achieving the effects of the present invention have not been clarified by such a configuration, it is presumed as follows at present. In other words, a conductive network that allows a plurality of components [A] to come into contact with each other to allow the conductive resin composition (or a molding material or a molded article) to conduct electricity uses a trace amount of the component [B] as a relay point. It is presumed that this is due to the formation (a very small amount of component [B] is preferentially present at the contact point between components [A]).

Preferred examples of the constitution of the conductive resin composition of the present invention include a constitution in which the constituent [B] is dispersed in the constituent [C] and at least a part of the constituent [A]. Is in contact with the component [B], which is presumed to be due to the mechanism described above. That is, although the details of the mechanism for achieving the effect of the present invention by adopting such a configuration are not clear, at present, the component [B] and the component [A] more frequently interact with each other. It is presumed that it is possible to operate and that the component [A] can be efficiently networked.

The component [B] is included in the component [C].
Is dispersed in the component [C] which is a matrix resin, in which the domains of the component [B] which is not compatible or semi-compatible with each other are scattered. The major axis of the domain when the boundary between the domain and the matrix resin is clear is preferably 0.01 to 100 μm.
m (more preferably 0.1 to 50 μm, further preferably 3 to 30 μm).

Further, the expression that at least a part of the component [A] is in contact with the component [B] means that at least a part of the component [A] (preferably 5% by weight of the component [A]).
Above, more preferably 15% by weight or more, and even more preferably 50% by weight or more) refers to the form in which the domain of the component [B] is in contact, and merely the form in which the domain of the component [B] is in contact. Not only that, a form that penetrates the domain of the component [B] or is included in the domain of the component [B] is included.

In the present invention, it has been found that the effect of the present invention can be specifically exhibited within the range of a very small amount of the component [B]. Conversely, if the compounding amount is out of the range of the present invention, especially if the compounding amount is excessive, the moldability (especially the thermal stability) becomes poor, and it is finally impossible to perform continuous molding. Become.

The constituent element [A] in the present invention is a discontinuous conductive fiber contained in an amount of 1 to 50% by weight in 100% by weight of the conductive resin composition. It is more preferably in the range of 4 to 40% by weight, and still more preferably in the range of 10 to 30% by weight. If the amount of the discontinuous conductive fiber is less than 1% by weight, desired conductivity cannot be obtained. If the amount exceeds 50% by weight, the specific gravity becomes high, which is disadvantageous for weight reduction.

Such discontinuous conductive fibers refer to all discontinuous fibers that are not insulating fibers. Here, the discontinuous fiber refers to a fiber that is not continuous in the obtained molded product, and its fiber length is preferably 1 μm to 15 cm (more preferably 5 μm to 15 mm, and still more preferably 10 μm to 7 μm).
mm). If the value is below the lower limit of the above numerical range, the conductivity of the obtained molded article will be low. If the value exceeds the upper limit, the appearance quality or molding will be difficult and the cost of the molded article will increase, which may be undesirable.

The discontinuous conductive fiber used in the present invention may be used alone as the discontinuous conductive fiber, or may be used in combination with the continuous conductive fiber in some cases. In addition, the form of the discontinuous fiber is not particularly limited,
For example, a chopped shape, a nonwoven fabric shape, an aggregated shape, a uniformly dispersed shape and the like can be mentioned.

Examples of the conductive fiber suitable as the discontinuous conductive fiber include a fiber having a single conductivity such as a carbon fiber and a metal fiber (such as a stainless steel fiber and a copper fiber). In addition, insulating fibers (organic fibers (aramid fibers, PBO fibers, polyphenylene sulfide fibers, polyester fibers, acrylic fibers, nylon fibers, polyethylene fibers, etc.) and inorganic fibers (glass fibers,
The conductive fiber includes a fiber in which a conductive material (metal, metal oxide, carbon, or the like) is coated on a silicon carbide fiber, a silicon nitride fiber, or the like, or a conductive fiber (metal fiber, carbon fiber, or the like). Further, two or more kinds of the conductive fibers may be used in combination, or the conductive fibers may be used in combination with an insulating fiber such as a glass fiber or an aramid fiber. Among them, carbon fibers excellent in balance among price, mechanical properties, conductivity and specific gravity are preferable.

Such carbon fibers include, for example, PAN type,
Pitch-based, cellulosic, and vapor-grown carbon fibers and graphite fibers based on hydrocarbons, and nickel, ytterbium, gold, silver, copper, and other metals are plated with a plating method (electrolysis, electroless), a CVD method, a PVD method, Ion plating method,
It refers to a metal-coated carbon fiber formed by coating at least one or more layers by a vapor deposition method or the like, or a material formed by blending two or more of these. As such a carbon fiber, a PAN-based carbon fiber having an excellent balance between mechanical properties such as strength and elastic modulus and price is preferable.

The carbon fibers used in the present invention include wide-angle X
The crystal size (hereinafter, referred to as Lc) measured by the line diffraction method is preferably in the range of 1 to 6 nm. When the Lc is less than 1 nm, carbonization or graphitization of the carbon fiber is not sufficient, and the conductivity of the carbon fiber itself becomes low. Due to this, the conductivity of the obtained conductive molded article may be poor. On the other hand, when Lc exceeds 6 nm, carbonization or graphitization of the carbon fiber is sufficient, and the carbon fiber itself is excellent in conductivity, but is fragile and easily broken. Due to this, the length of the fiber in the conductive molded body is shortened, and it is not preferable because excellent conductivity cannot be expected. Lc is more preferably 1.3 to 4.5 nm,
More preferably, it is in the range of 1.6 to 3.5 nm.
Particularly preferably, the thickness is in the range of 1.8 to 2.8 nm. The measurement of Lc by the wide-angle X-ray diffraction method was performed by the 117th Committee of the Japan Society for the Promotion of Science, Carbon, 36, p2
5 (1963).

The discontinuous conductive fiber used in the present invention may be provided with a sizing agent in advance in order to provide excellent mechanical properties and high convergence. Here, the sizing agent is preferably water-soluble in view of its working environment.

Examples of the sizing agent include silane, aluminate, titanate and other coupling agents, epoxy, urethane, ether, ester, amide, acrylic, olefin, vinyl, and the like.
Styrene-based, silicon-based, fluorine-based, phenol-based resins, liquid-crystalline resins, and the like, among which amide-based resins and / or vinyl-based resins that maximize the effects of the present invention are preferably used as sizing agents. .

Typical examples of such amide resins include polyamide resins containing an alkylene oxide component and a tertiary amine component in the molecular chain, nylon 8 resins, and modified resins thereof. Examples of the component in which the polyalkylene oxide component is introduced into the molecular chain of the amide resin include those obtained by modifying a part of polyethylene glycol, polypropylene glycol or the like with diamine or dicarboxylic acid and copolymerizing the same. Examples of the tertiary amine to be introduced into the molecular chain of the polyamide resin include:
When introduced into the main chain, for example, aminoethylpiperazine and bisaminopropylpiperazine are used. When introduced into the side chain, α-dimethylamino ε-caprolactam is used.

Among these amide resins, a water-soluble amide resin containing a polyalkylene oxide component in its molecular chain is preferable because the effects of the present invention can be maximized. In the case of a water-soluble polyamide resin containing a tertiary amine component, particularly when subjected to high-temperature molding at a molding temperature of about 300 ° C., the fluidity is not sufficient, and uniform dispersion of the conductive fiber bundle is achieved. Care must be taken because it may not be possible.

As the vinyl resin, a polyvinyl alcohol resin described below is preferable, and a water-soluble vinyl resin is more preferable.

In the present invention, the component [B] is a polyvinyl alcohol resin contained in an amount of 0.01 to 6% by weight in 100% by weight of the conductive resin composition. More preferably 0.1 to 4% by weight, further preferably 0.5 to 4% by weight.
Preferably, it is in the range of ~ 3.5 wt%, especially 1-3 wt%. When the polyvinyl alcohol resin is contained in an amount of 0.
If the amount is less than 01% by weight or exceeds 6% by weight, the conductive effect of the present invention cannot be exhibited.

The component [B] includes a homo- or co-vinyl alcohol resin obtained by saponifying a vinyl ester unit of a vinyl ester polymer. Examples of the vinyl compound monomer that forms the vinyl ester unit include vinyl formate, vinyl acetate, vinyl propionate, and vinyl pivalate, and vinyl acetate is preferred from the viewpoint of the production method.

Such a vinyl alcohol resin may be used as a copolymer from the viewpoint of thermal stability, and α-olefins (ethylene, propylene,
1-butene, isobutene, etc.), hydroxy group-containing α-olefins, alkyl vinyl ethers (methyl vinyl ether, ethyl vinyl ether, etc.), hydroxyalkyl vinyl ethers (ether glycol vinyl ether, 1,3-propanediol vinyl ether, etc.),
Examples include allyl esters (such as allyl acetate). Among them, α-olefins, particularly ethylene, are preferable as the copolymerized unit in terms of thermal stability and cost.

In the present invention, the constituent element [C] is a polyamide resin. As such polyamide resin, 15
Nylon resin having a melting point of 0 ° C. or more and excellent in heat resistance and strength can be mentioned. Specific examples include nylon 6, nylon 66, nylon 46, nylon 610, and nylon 6.
12, Nylon 9T, Nylon 66/6, Nylon 66
/ 6T, nylon 66 / 6I, nylon 6 / 6T, nylon 6 / 6I, nylon 12 / 6T, nylon 6T / 6
I, nylon 66 / 6T / 6I, nylon 66/6/6
T, nylon 66/6 / 6I, nylon 6T / M5T,
Nylon XD6, polymethaxylylene adipamide, and copolymers or mixtures thereof can be preferably used. Further, depending on the necessity of improving properties (particularly impact resistance), for example, it is selected from maleic anhydride-modified olefin polymers, olefin copolymers such as ABS and ASA, and elastomers such as polyester polyether and polyester polyester. One or a mixture of two or more of these may be added to use those further imparted with desired properties.

There is no particular limitation on the degree of polymerization of the polyamide resin, but it is preferable that the polyamide resin has a certain degree of fluidity so that uniform dispersion of the constituent element [A] can be achieved. Polyamide resins in the range of 3.5 are preferred. More preferably 1.8 to
3, more preferably in the range of 2 to 2.5. The sulfuric acid relative viscosity ηr was determined by dissolving 98% sulfuric acid so that the solution concentration became 1 g / 100 ml,
The flow velocity is measured with an Ostwald viscometer in a constant temperature bath of
It refers to the ratio of the number of seconds during which the sample solution flows to 98% sulfuric acid.

The constituent element [C] is composed of the conductive resin composition 10
The content is preferably in the range of 10 to 99% by weight (more preferably 30 to 90% by weight, and still more preferably 50 to 80% by weight) in 0% by weight.

As another example of a preferred configuration of the conductive resin composition of the present invention, a water-soluble amide resin and / or a water-soluble amide resin may be formed on the surface of the component [A] at least as the component [D]. And those having a conductive vinyl resin. Specific resin types of the water-soluble amide resin and / or the water-soluble vinyl resin include the water-soluble amide resin described in the description of the sizing agent and the polyvinyl alcohol resin described in the description of the component [B]. The same resin as the resin (water-soluble vinyl resin) can be used. Although the details of the mechanism for exhibiting the effects of the present invention with such a configuration are not clear, the interaction between the component [B] and the component [A] is stronger at present. It can be inferred that the component [A] can be networked more efficiently.

It should be noted that having the component [D] on the surface of the component [A] means that at least a part of the domain composed of the component [D] is in direct contact with the component [A]. is there. Direct contact means that no intervening phase such as a gas phase or a matrix resin phase is interposed therebetween. However, even if the intermediary phase is intervened, if it is about 20 nm or less, it can be ignored. . This is because, to that extent, the conductivity is not impaired.

The conductive resin composition of the present invention may further contain carbon powder as a component [E] in order to obtain higher conductivity efficiently and inexpensively. In order to simultaneously satisfy particularly excellent conductivity such as volume resistivity and surface resistance and low specific gravity at the same time, it is preferable to minimize the amount of the component [A], but in that case the conductivity is low. Decrease. Even in such a case, by using the component [E] in addition to the component [A], efficient conductivity can be achieved, and the blending amount of the component [A] can be suppressed to a minimum. If you need particularly good conductivity,
It is preferable to use the component [A] and the component [E] together.

Here, the carbon powder includes, for example, carbon black, amorphous carbon powder, natural graphite powder,
Artificial graphite powder, expanded graphite powder, pitch micro beads,
Examples include single-walled and / or multi-walled carbon nanotubes, and among them, carbon black or carbon nanotubes having high effects are preferable.

The constituent element [E] is composed of the conductive resin composition 10
0% by weight, preferably 0.1 to 10% by weight (more preferably 0.2 to 5% by weight, further preferably 0.5 to 3% by weight).
% By weight).

The conductive resin composition of the present invention may further contain a flame retardant as a component [F] in order to obtain high flame retardancy.

Since high flame retardancy can be imparted when such a component [F] is blended, the flame retardancy at a thickness of 1.6 mm (1/16 inch) is V-94 in the UL-94 standard.
It is preferably used as a conductive composition or a molded article having zero or better conductivity.

Here, the flame retardancy of V-0 is defined as UL-94.
V-0 conditions specified in the standards (US combustion test method devised by Underwriters Laboratories Inc.) based on the burning time, its condition, the presence or absence of fire spread, the presence or absence of dripping and the flammability of the dripping material, etc. Refers to flame retardancy that satisfies. Further, flame retardancy better than V-0 means that
The flame retardancy, which indicates a combustion time even shorter than the specified value in the −0 class, or V when the thickness of the test piece is thinner
Refers to flame retardancy that satisfies the specified condition of −0.

Here, the flame retardant means at least one of a halogen compound (eg, a brominated resin) or an antimony compound (eg, antimony trioxide, antimony pentoxide, etc.)
Or a non-halogen phosphorus compound (for example, ammonium polyphosphate, polyphosphazene, phosphate,
Phosphonates, phosphinates, phosphine oxides,
Red phosphorus, etc.), nitrogen compounds (eg, cyanuric acid, isocyanuric acid, melamine, melamine cyanurate, melamine phosphate, nitrated guanidine, etc.), silicone compounds (eg, polyorganosiloxane, etc.), fluorine compounds (eg, PTFE, etc.) Alternatively, metal hydroxides (eg, aluminum hydroxide, magnesium hydroxide, etc.), organic acid metal salts (eg, organic borate metal salts, carboxylate metal salts, aromatic sulfonimide metal salts, etc.), and other inorganic types (For example, zinc borate, zinc, zinc oxide, zirconium compound, etc.).

Component [F] is preferably 1 to 30% by weight (more preferably 3 to 20% by weight, more preferably 5 to 15% by weight) in 100% by weight of the conductive resin composition molded article. It is contained within the range.

The conductive resin composition of the present invention may further comprise a filler (mica, talc, kaolin, sericite, bentonite, zonotolite, sepiolite, smectite, montmorillonite, wollastenite, silica, calcium carbonate, glass Beads, glass flakes,
Glass microballoon, clay, molybdenum disulfide,
Titanium oxide, zinc oxide, antimony oxide, calcium polyphosphate, graphite, barium sulfate, magnesium sulfate, zinc borate, calcium borate, aluminum borate whisker, potassium titanate whisker, polymer, etc., conductivity-imparting material (metal) System, metal oxide system, etc.), flame retardant aids (cadmium oxide, zinc oxide, cuprous oxide, cupric oxide, ferrous oxide, ferric oxide, cobalt oxide, manganese oxide, molybdenum oxide, oxide Tin, titanium oxide, etc.), pigments, dyes, lubricants, release agents, compatibilizers, dispersants, crystal nucleating agents (mica, talc, kaolin, etc.), plasticizers (phosphate esters, etc.), heat stabilizers, oxidation Inhibitor, anti-coloring agent, ultraviolet absorber, fluidity modifier, foaming agent, antibacterial agent, vibration damper, deodorant, slidability modifier, antistatic agent (polyetherester Any additives such as Donado), alone, can be used in a blend of two or more.

Next, the molding material of the present invention will be described.
The molding material of the present invention comprises the above-mentioned conductive resin composition.

The details and weight ratio of each component are the same as those described for the conductive resin composition of the present invention as described above.

Components [A], [B] and [C] of the present invention
The method for molding the molding material is not particularly limited. For example, (1) melt-kneading the components [B] and [C] (other components as necessary) with an extruder or the like; A method of further mixing or contacting the component [A] (preferably having the component [D] adhered to its surface) to obtain a molding material and molding; (2) the components [B] and [C] Is melt-kneaded with an extruder or the like, and another molding material containing at least the component [A] (preferably having the component [D] adhered to its surface) is mixed. (3) Component [A] (preferably having component [D] adhered to its surface),
A method in which [B] and [C] are simultaneously mixed by melt-kneading in an extruder or the like to obtain a molding material and mold.

The form of the molding material of the present invention includes pellets, stampable sheets, prepregs, SMC, BMC
And the like. However, a preferable molding material is a pellet used for injection molding, and more preferably, discontinuous conductive fibers as a component [A] are arranged substantially parallel to the longitudinal direction of the pellet. It is a long fiber pellet (the average fiber length of the component [A] is preferably 1 to 15 mm, more preferably 3 to 10 mm) in which the fiber length is substantially the same as the pellet length. In this case, the constituent elements [B] and [C] may be either impregnated inside the constituent element [A] or coated on the surface thereof.

In particular, in the case of long fiber pellets coated with the constituents [B] and [C] as the sheath, at least the sizing agent, preferably the constituent [B] is added to the constituent [A] as the core. ], [C], more preferably a resin having a lower viscosity (or lower molecular weight) than the above-mentioned constituents [B] and [C] is impregnated beforehand, and contains at least the constituent [A] as a main component. It is preferable to have a core-sheath structure including a core portion and a sheath portion having at least components [B] and [C] as main components. By adopting such a structure, the productivity of long fiber pellets can be further improved, and scattering of the component [A] can be minimized.

Further, such long fiber pellets include those obtained by mixing long fiber pellets or a mixture of long fiber pellets and other pellets by dry blending. When dry-blended with other pellets, the weight% of the components [A], [B] and [C] in the dry-blended
It is important that the weight ratio is within the range of the weight ratio of the resin composition of the present invention. That is, when individual pellets of the dry blend are individually observed, even when there is no pellet within the composition range of the resin composition of the present invention, the composition of the entire dry blend mixture is determined. Wherein the composition is
When the composition falls within the range of the composition of the resin composition of the present invention, the dry blend, that is, the molding material, is regarded as having the resin composition of the present invention. That is, even the dry blend as described above is a molding material that falls within the technical scope of the present invention. Mixing by dry blending not only minimizes the investment in long fiber pellet production equipment, but also does not impair the effects of the present invention, and in some cases, further enhances the effects of the present invention to form the product. enable.

When the molding material of the present invention is in the form of such long fiber pellets, the constituent element [A] in the molded body is obtained.
Can be lengthened, and the effects of the present invention can be maximized.

The molded article made of the conductive resin composition or the molding material of the present invention can be prepared by, for example, injection molding (injection compression molding, gas assist injection molding, insert molding, etc.), blow molding, rotational molding, extrusion molding, press molding, or the like. Molding may be performed by a molding method such as transfer molding (RTM molding, RIM molding, SCRIMP molding, etc., in which case the component [A] is preferably in the form of nonwoven fabric), autoclave molding, hand lay-up molding, etc. Although it is possible, a desirable molding method is to perform molding by injection molding with high productivity. The molding temperature is appropriately determined depending on the type and the mixing ratio of the components used, but is preferably within a range of a molding temperature suitable for the component [C] (for example, a recommended molding temperature described in a product catalog). Preferably it is.

The molded article of the present invention can be used as a member in the field of electronic / electric equipment, OA equipment, home electric equipment, automobile, or precision equipment in which excellent conductivity and mechanical properties (particularly rigidity) are required. Preferred examples include a housing, a casing, a cover, a tray, and parts thereof, and particularly preferred are a housing of a portable electronic / electric device and the like, which are particularly required to be lightweight and have high electromagnetic wave shielding properties. More specifically, a large display, a notebook computer, a portable telephone, a PHS, a personal digital assistant (PDA, etc.), a video camera, a video camera,
Digital still cameras, portable radio cassette players,
Housings such as inverters and casings.

Further, since the molded article of the present invention has excellent conductivity, it can be provided with a charge / discharge preventing property by adding a small amount of the component [A]. It is also useful for adaptation to members to be used, for example, IC trays, baskets for transporting silicon wafers, and the like.

[0062]

The present invention will be described in more detail with reference to the following examples. The evaluation items relating to the characteristics of the molded article of the present invention and the evaluation method are described below.

(1) Specific Gravity AS
The specific gravity was measured based on TM D792.

(2) Volume Specific Resistance First, a width of 12.7 mm × length of 65 mm × thickness of 2 mm (hereinafter, the above three sides are defined as sides A, B and C, and a direction parallel to each side is defined as a direction a, b, c, and a rectangular surface having sides A, B is defined as a surface AB, and other surfaces (BC, CA) are similarly defined.) A test piece was formed by injection molding with a fan gate (gate dimension: direction b: 5 mm, direction c: 2 mm) positioned so as to be in contact with one side C of the BC surface of the mold. Next, a conductive paste (Doitite manufactured by Fujikura Kasei Co., Ltd.) is applied to the two surfaces AB of the molded test piece, and the conductive paste is sufficiently dried.
05% or less). Upon measurement, the two surfaces AB were pressed against the electrodes, and the electrical resistance between the electrodes was measured with a digital multimeter (R6581 manufactured by Advantest). A value obtained by subtracting the contact resistance of a measuring instrument, a jig or the like from the electric resistance value was multiplied by the area of the conductive paste applied surface, and then the value was divided by the length of the test piece to obtain a specific resistance value (unit). Is logΩ · cm or Ω · cm).
In this measurement, 10 samples were measured, and the average value thereof was used.

(3) Rigidity (elastic modulus) ASTM D 790 (distance between spans L / thickness D = 1)
The rigidity was evaluated by the flexural modulus based on 6) (unit: GPa). The test specimens used were 6.4 mm (1/4 inch) thick and had a moisture content of 0.05% or less. In this measurement, five samples were measured, and the average value thereof was used.

(4) Izod Impact Strength With Mold Notch Based on ASTM D256
The evaluation was made based on the zod impact strength (unit: J / m). The test pieces used were 3.2 mm (1/8 inch) thick and had a moisture content of 0.05% or less. In this measurement, 1
Zero samples were measured and their average was used.

Example 1, Comparative Examples 1 to 5 Desired amounts of components [B] and [C] sufficiently dried to a moisture content of 0.05% or less were charged from a main hopper of a twin-screw extruder, and sufficiently melted. While being extruded in a kneaded state, a desired amount of a 6 mm long chopped component [A] bundle sufficiently dried to a moisture content of 0.05% or less is charged from a side hopper, and the components [B], [C] ] Was impregnated into the bundle of the component [A]. The component [A] thus obtained
Was cooled, and then cut into 5 mm with a cutter to obtain pellets.

Table 1 shows the types of the constituent elements and other components and the compounding ratio thereof. After drying the obtained pellets in vacuum at 100 ° C. for 5 hours or more,
Injection molding was performed at a barrel temperature of 260 ° C. and a mold temperature of 80 ° C., and subjected to the tests described in the above items (1) to (4). Table 1 shows the evaluation results.

[0069]

[Table 1]

Examples 2 to 5, Comparative Example 6 A desired amount of the constituents [B] and [C] sufficiently dried to a moisture content of 0.05% or less and, if necessary, other components were added to a twin-screw extruder. The mixture was extruded while being sufficiently melted and kneaded to prepare a master pellet in which the constituent elements [B], [C], and other components were uniformly dispersed.

The above master pellets are extruded by a single screw extruder.
Fully melts in the crosshead die attached to the tip
While extruding in a kneaded state, a continuous fibrous component [A] bundle sufficiently dried to a moisture content of 0.05% or less is also continuously supplied into the crosshead die, and the components [B] and [C] ] Were sufficiently impregnated into the bundle of the component [A]. Here, the crosshead die refers to a device that impregnates a molten resin or the like therein while opening a continuous component [A] bundle in the die. Strands in which the constituents [B] and [C] are sufficiently impregnated in the bundle of the constituents [A] are further extruded with the master pellet and coated by an electric wire coating method, so that at least the constituent [A] is mainly used. The core-sheath structure was composed of a core part as a component and a sheath part containing at least constituents [B] and [C] as main components. The thus obtained strand containing the continuous fibrous component [A] bundle was cooled and then cut into 7 mm with a cutter to obtain a long fiber pellet.

Table 2 shows the types of the constituent elements and other components and the compounding ratio thereof. After the obtained pellets were dried in vacuum at 80 ° C. for 5 hours or more, they were injection-molded at a barrel temperature of 260 ° C. and a mold temperature of 80 ° C. for each test described in (1) to (4). It was subjected to injection molding. Table 2 shows the evaluation results.

[0073]

[Table 2]

The notation of each component in Tables 1 and 2 is based on the following. Constituent element [A] CF1: PAN-based carbon fiber [average single fiber diameter = 7 μm
m, Lc = 1.7 nm] CF2: PAN-based carbon fiber [CF1 (99% by weight) to which AQ nylon (1% by weight) manufactured by Toray is adhered] CF3: Ni-coated PAN-based carbon fiber [CF1 (54 parts by weight) Ni (46 parts by weight) Ni-coated carbon fibers (99% by weight) coated with electrolytic plating and Toray AQ nylon (1% by weight) adhered] Component [B PVA1: Polyvinyl alcohol resin [Povar made by Kuraray] PVA2: Polyvinyl alcohol resin [RS polymer made by Kuraray] Component [C] PA: Nylon 66/6 / 6I copolymer resin [Sulfuric acid relative viscosity ηr = 2.0] Constituents PET: Polyethylene terephthalate resin [number average molecular weight = 22000] PE: High density polyethylene resin [Hizex made by Grand Polymer] PC: polycarbonate resin [Lexan 121 manufactured by GE Plastics] PPE: polyphenylene ether resin [YPX900F manufactured by Mitsubishi Gas Chemical] From the results of Tables 1 and 2, the following became clear. 1. Effect of Component [B] Compared to Comparative Examples 1 to 5 (Comparative Example 6) in which Component [B] of the present invention is not used (other components are used), Component [B] of the present invention is used. In Example 1 (Examples 2 to 5), the volume resistivity was remarkably reduced, and a molded article having significantly excellent conductivity (small volume resistivity) was obtained.

Further, as compared with Comparative Example 5 in which the constituent element [A] was blended in a large amount, Example 1 in which the blending amount of the constituent element [A] was small had the same conductivity or more (the volume specific resistance value was the same or less). ) However, the specific gravity can be significantly reduced, and its superiority has become clear. 2. Effects of long fiber pellets In comparison with Example 1 using normal pellets, Examples 2 to 5 using long fiber pellets can have lower volume resistivity and are more excellent in conductivity. Could be obtained. This is because the length of the component [A] in the molded body was longer in Examples 2 to 5 than in Example 1 (depending on the manufacturing method). That is, while the weight average fiber length in the molded article of Example 2 was 0.41 mm, in the case of Example 1, the weight average fiber length in the obtained molded article was 0.1 mm. It was 25 mm.

From these comparisons, the importance of the length of the component [A] on the conductivity is apparent. As a molding material for obtaining the conductive molded article of the present invention, the fiber length should be as long as possible. It has been found that it is more preferable to take the form of a molded material (pellets in the case of injection molding), especially long fiber pellets.

[0077]

The conductive resin composition or molding material of the present invention comprises at least 1 to 50% by weight of discontinuous conductive fibers, 0.01 to 6% by weight of polyvinyl alcohol resin and polyamide resin. As a result, a molded article having both excellent conductivity and low specific gravity can be provided.

According to such a molded article, since it has both low specific gravity and excellent conductivity, it is particularly suitable for electric and electronic equipment.
A molded product suitable for a wide range of industrial fields such as housings, casings, trays for OA equipment, precision equipment, and automobiles can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 9/02 C08K 9/02 9/04 9/04 C08L 29/04 C08L 29/04 D H01B 1/00 H01B 1/00 C 1/20 1/20 Z 1/24 1/24 Z // B29K 29:00 B29K 29:00 77:00 77:00 105: 12 105: 12 F term (reference) 4F071 AA29 AA54 AB03 AD01 AE15 BB05 4F201 AA19 AA29 AB13 AB18 AB25 AB28 AE03 AH17 AH25 AH33 BA02 BC02 BC15 BC37 BD04 BL44 BL45 4J002 BE02W CL00X DA016 FA046 FB076 FB266 FD116 5G301 DA03 DA05 DA06 DA10 DA18 DA20 DA51 DA60 DD10

Claims (9)

[Claims] 1. At least the following components [A]:
It is a conductive resin composition having [B] and [C], and the weight ratio of the component [A] is 1
To 50% by weight, and the content of the component [B] is 0.1% by weight.
A conductive resin composition characterized in that the content is from 01 to 6% by weight. Component [A]: discontinuous conductive fiber. Component [B]: polyvinyl alcohol resin. Component [C]: polyamide resin. 2. The method according to claim 1, wherein the component [A] is a carbon fiber and / or
The conductive resin composition according to claim 1, which is a metal-coated carbon fiber. 3. The component [B] in the component [C].
The conductive resin composition according to claim 1, wherein the conductive resin composition is dispersed. 4. The method according to claim 1, wherein at least a part of the component [A] is in contact with the component [B].
The conductive resin composition according to any one of the above. 5. The conductive resin composition according to claim 1, which has the following component [D] on the surface of the component [A]. Component [D]: water-soluble polyamide resin and / or polyvinyl alcohol resin. 6. A molding material comprising the conductive resin composition according to claim 1. 7. The molding material according to claim 6, which has a form of a long fiber pellet. 8. A molded article obtained by molding the conductive resin composition according to claim 1 or the molding material according to claim 6 or 7. 9. The molded article according to claim 8, which is used for a housing, a casing, or a part thereof in an electric / electronic device, an OA device, a home appliance, or an automobile field.