JP2002338794A - Electrically conductive resin composition and molding material or molded part prepared from the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically conductive resin composition which may yield an excellent electric conductivity at a low specific weight, and a molding material and a molded part prepared from this. SOLUTION: The electrically conductive resin composition or the molding material comprises at least an electrically conductive discontinuous fiber as constituent [A], a polybutylene terephthalate resin and/or a liquid crystal polyester resin as constituent [B] and a polycarbonate resin as constituent [C]. Here, the composition comprises constituents [A] and [B] at weight ratios of 1 to 50 wt.% and 0.01 to 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 a technique for increasing the conductivity by devising the resin composition of the resin composition described above, a technique in which a plurality of resins are used in combination is cited as an example, for example, Japanese Patent Application Laid-Open No. 5-287143.
In the publications, a polyalkylene phthalate-based resin is blended in a thermoplastic resin, conductive carbon is unevenly distributed in the polyalkylene phthalate-based resin, and the fact that the polyalkylene phthalate-based resin can be made to have a high conductivity by making it a continuous phase. There is a description.

However, according to this proposal, it is necessary to make the conductive material unevenly distributed in one of the resins and to make the resin a continuous phase, and there is a problem that there is a limitation particularly in the production of a molding material. Exists. 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 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.

[0008]

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.

[0009]

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]: a polybutylene terephthalate resin and / or a liquid crystal polyester resin.

Component [C]: polycarbonate resin.

[0013] The molding material of the present invention is characterized by comprising 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.

[0015]

Embodiments of the present invention will be described below.

The conductive resin composition of the present invention is a conductive resin composition comprising at least the following components [A], [B] and [C], and the weight ratio is 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]: a polybutylene terephthalate resin and / or a liquid crystal polyester resin.

Component [C]: polycarbonate resin.

Although the details of the mechanism for exhibiting 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]).

The conductive resin composition of the present invention preferably has a specific configuration in which the component [B] is dispersed in the component [C] or at least a part of the component [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).

[0023] Further, 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.

According to the present invention, it has been found that the effects of the present invention can be specifically exhibited within the range of a very small amount of the component [B]. This will be described in more detail with reference to FIG. FIG. 1 is a graph showing the effect of improving conductivity when the amount of component [B] is changed in a molded article made of the conductive resin composition of the present invention (component [A]). , [B] and [C] were molded into 1
Component [A]: PAN-based carbon fiber (CF1 in Examples) as 20% by weight; component [B]:
Polybutylene terephthalate (PBT in Examples); 0
-80% by weight, component [C]: polycarbonate (PC in Examples); 80-0% by weight, other components:
Each component was blended so as to be 0% by weight). As is clear from FIG. 1, the specific effect of the present invention is exhibited when the amount of the component [B] is extremely small. Conversely, if the amount is outside the scope of the present invention, especially if the amount is excessive,
Rather, the conductivity tends to deteriorate.

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 a discontinuous conductive fiber or may be used in combination with a continuous conductive fiber. Further, the form of the discontinuous fiber is not particularly limited, and examples thereof include a chopped form, a nonwoven fabric form, an aggregate form, and a uniform dispersion form.

Examples of the conductive fiber suitable as such a discontinuous conductive fiber include carbon fiber, metal fiber (stainless steel fiber, copper fiber, etc.) and the like, which independently show conductivity. 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-based
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 ester-based and / or ether-based resins that maximize the effects of the present invention are preferably used as sizing agents. .

As such an ester resin, a polyalkylene oxide chain, a sulfonic acid group or a polyalkylene oxide chain in the molecular chain or at the terminal group of the same polybutylene terephthalate resin as described in detail in the description of the constituent element [B] below. Its salt,
It is preferable to introduce a carboxyl group or a salt thereof, an amino group or a salt thereof, and express water solubility.

Examples of such ether resins include polyethylene glycol, polypropylene glycol, polyalkylene glycols including copolymers thereof, polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, and the like. Addition resins are preferred.

In the present invention, the component [B] is a polybutylene terephthalate resin and / or a liquid crystalline polyester resin contained in an amount of 0.01 to 6% by weight in 100% by weight of the conductive resin composition. is there. More preferably 0.1 to 4% by weight, even more preferably 0.5 to 3.5%.
It is preferably in the range of from 1 to 3% by weight. Such polybutylene terephthalate resin and / or
Alternatively, if the content of the liquid crystalline polyester resin is less than 0.01% by weight or exceeds 6% by weight, the conductive effect of the present invention cannot be exhibited.

As the component [B], only polybutylene terephthalate resin or liquid crystalline polyester resin may be used, or both may be mixed or block copolymerized. However, polybutylene terephthalate is preferred from the viewpoint of material cost. It is preferably a resin. The polybutylene terephthalate resin (or liquid crystalline polyester resin) may be composed of a plurality of types.

Examples of the polybutylene terephthalate resin include a high-molecular-weight thermoplastic polyester resin having an ester bond in a main chain, using terephthalic acid as an acid component and 1,4-butanediol as a glycol component. It is also possible to copolymerize other copolymerizable components. For example, as an acid component, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, oxalic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, etc., and as a glycol component, ethylene glycol, propylene glycol, tetramethylene glycol, , 6-hexanediol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol A
Also, an ethylene oxide adduct of the above can be used.

As described above, the amount of copolymerization when another component is copolymerized is not particularly limited as long as its properties are not significantly impaired, and is 0 to the total number of moles of the dicarboxylic acid unit and the glycol unit. It is preferably in the range of 範 囲 30 mol%. More preferably, it is in the range of 0 to 25 mol%, still more preferably in the range of 0 to 20 mol%.

The polybutylene terephthalate resin used in the present invention has a number average molecular weight (in terms of GPC styrene) of from the viewpoint of the effect of imparting conductivity and the moldability of the conductive molded article.
It is preferably in the range of 2000 to 40,000, more preferably 10,000 to 30,000, especially 150
Those within the range of 00 to 25000 are preferable.

As such a liquid crystalline polyester resin,
Like liquid crystal polyester resin, liquid crystal polyester amide resin, liquid crystal polyester elastomer resin, etc.
It refers to those having an ester bond in the molecular chain, and is particularly preferably liquid crystal polyester.

In the present invention, the component [C] is a polycarbonate resin. Examples of such polycarbonate resins include aromatic homo- or copolycarbonate resins having a viscosity average molecular weight in the range of 10,000 to 1,000,000 obtained by reacting an aromatic dihydric phenol compound with phosgene or a carbonic acid diester.

Specific examples of the dihydric phenol compound here include 2,2-bis (4-hydroxyphenyl)
Propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4 -Hydroxyphenyl)
Butane, 2,2-bis (4-hydroxy-3,5-diphenyl) butane, 2,2-bis (4-hydroxy-3,
5-diethylphenyl) propane, 2,2-bis (4-
(Hydroxy-3,5-diethylphenyl) propane,
Examples thereof include 1,1-bis (4-hydroxyphenyl) cyclohexane and 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, which can be used alone or as a mixture.

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 the preferred constitution of the conductive resin composition of the present invention, a water-soluble ester resin and / or a water-soluble resin may be formed on the surface of the constituent element [A] at least as the constituent element [D]. And those having a functional ether-based resin. Specific resin types of the water-soluble ester-based resin and / or the water-soluble ether-based resin include:
The same water-soluble ester-based resin and / or water-soluble ether-based resin mentioned in the description of the sizing agent 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 a styrene-based resin as a component [E] in order to efficiently and inexpensively obtain a higher appearance quality in a molded article.

The styrenic resin contains a unit formed from styrene and / or a derivative thereof (generally referred to as an aromatic vinyl monomer).

As such a styrene-based resin, a styrene-based (co) polymer (here, “(co) polymer” means “polymer and / or copolymer”, and the same applies hereinafter. ) And rubber-reinforced styrene (co) polymers.
Examples of the styrene (co) polymer include polymers obtained by polymerizing one or more aromatic vinyl monomers, and one or more aromatic vinyl monomers that can be copolymerized therewith. And copolymers obtained by copolymerizing one or more monomers. The rubber-reinforced styrene (co) polymer has a structure in which a (co) polymer containing a styrene monomer is grafted to a rubbery polymer and a (co) polymer containing a styrene monomer. One having a structure in which the union is non-grafted to the rubbery polymer.

Preferred styrene resins in the present invention 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 constituent element [E] is composed of the conductive resin composition 10
The content is preferably 0.1 to 70% by weight (more preferably 1 to 40% by weight, and still more preferably 3 to 20% by weight) in 0% by weight.

The conductive resin composition of the present invention may further contain carbon powder as a constituent element [F] 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 that case, by using the component [F] in addition to the component [A], efficient conductivity can be achieved, and the amount of the component [A] can be minimized. When particularly excellent conductivity is required, it is preferable to use the component [A] and the component [F] 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 [F] 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 [G] in order to obtain high flame retardancy.

When such a component [G] is blended, high flame retardancy can be imparted. Therefore, in the UL-94 standard, the flame retardancy at a thickness of 1.6 mm (1/16 inch) is V-.
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.).

The component [G] is composed of the conductive resin composition 10
0% by weight, preferably 1 to 30% by weight (more preferably 3 to 20% by weight, still more preferably 5 to 15% by weight)
It is contained within the range of.

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) depending on the purpose. 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 is characterized by comprising the 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], [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, the long fiber pellets of the present invention include those obtained by mixing long fiber pellets or a mixture of long fiber pellets and other pellets by dry blending. When dry-blending with other pellets, it is important that the weight percentages of the constituent elements [A], [B], and [C] in the dry blend are the weight ratios as in the resin composition of the present invention. is there. 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 takes 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 may be used in electronic / electric equipment, OA equipment, home electric appliances, automobiles, or members of the field of precision equipment requiring excellent conductivity and mechanical properties (especially rigidity), for example, 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 constituent element [A]. It is also useful for adaptation to members to be used, for example, IC trays, baskets for transporting silicon wafers, and the like.

[0070]

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, width 12.7 mm × length 65 mm × thickness 2 mm (hereinafter, the above three sides are defined as sides A, B and C, and the direction parallel to each side is defined as 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 I
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 the main hopper of the 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] and [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 320 ° 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.

[0076]

[Table 1]

Examples 2 to 6, Comparative Examples 6 and 7 Biaxial extrusion of desired amounts of components [B] and [C], which were sufficiently dried to a water content of 0.05% or less, and other components as necessary. Extrusion was performed while sufficiently melting and kneading with a machine to prepare master pellets in which the constituent elements [B], [C], and other components were uniformly dispersed.

The master pellets were 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. The obtained pellets were dried in vacuum at 80 ° C. for 5 hours or more, and then injection-molded at a barrel temperature of 320 ° 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.

[0080]

[Table 2]

The notation of each component in Tables 1 and 2 is based on the following. Component [A] CF1: PAN-based carbon fiber [average single fiber diameter = 7 μm,
Lc = 1.7 nm] CF2: PAN-based carbon fiber [CF1 (99% by weight) on the surface of Finetex ES- manufactured by Dainippon Ink and Chemicals, Ltd.
801 (1% by weight) is adhered] CF3: Ni-coated PAN-based carbon fiber [Ni-coated carbon fiber (99% by weight) obtained by coating Ni (46% by weight) on the surface of CF1 (54% by weight) with electrolytic plating. ) To which Finetex ES-801 (1% by weight) manufactured by Dainippon Ink and Chemicals is adhered.] Component [B] PBT: polybutylene terephthalate resin [number average molecular weight = 19000] LCP: liquid crystal polyester resin [p 995 parts by weight of hydroxybenzoic acid, 4,4'-dihydroxybiphenyl 1
26 parts by weight, 112 parts by weight of terephthalic acid, 216 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g, and 969 parts by weight of acetic anhydride were charged into a reaction vessel equipped with stirring blades and a distillation tube, and polymerized. What did you do. 80 mol% of aromatic oxycarbonyl units, 7.5 of aromatic dioxy units
Liquid crystal resin having a melting point of 314 ° C. and a melt viscosity of 20 Pa · s composed of 1 mol% of ethylenedioxy units and 20 mol% of aromatic dicarboxylic acid units] Component [C] PC: polycarbonate resin [Nippon GE Plastics] Lexan manufactured by Susan) Other components PET: polyethylene terephthalate resin [number average molecular weight = 22000] PA: nylon 6 resin [relative viscosity of sulfuric acid ηr = 2.4] PE: high-density polyethylene resin [Hisex made by Grand Polymer] Table 1, From the result of No. 2, the following became clear. 1. Effect of Component [B] The component [B] of the present invention is compared with Comparative Examples 1 to 5 (Comparative Examples 6 and 7) in which the component [B] of the present invention is not used (other components are used). Example 1 using Examples (Examples 2 to 6)
Can significantly lower the volume specific resistance value, and can obtain a molded article having excellent conductivity (small volume specific resistance value).

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 smaller was equivalent in conductivity or higher (volume resistivity was equal to or lower). ) 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 ordinary pellets, Examples 2 to 6 using long fiber pellets can have a lower volume resistivity and have more excellent conductivity. Could be obtained. This is because the length of the component [A] in the molded body was longer in Examples 2 to 6 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 0.39 mm, in the case of Example 1, the weight average fiber length in the obtained molded article was 0.19 mm. Because it was 22 mm.

From these comparisons, the importance of the length of the component [A] on the conductivity is clear, and 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.

[0084]

The conductive resin composition or molding material of the present invention comprises at least 1 to 50% by weight of discontinuous conductive fibers and 0.01 to 6% by weight of a polybutylene terephthalate resin and / or a liquid crystal polyester. By comprising a resin and a polycarbonate resin, it is possible to provide a molded article having both excellent conductivity and low specific gravity.

Since such a molded article 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.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of improving conductivity when the amount of component [B] is changed in a molded article made of a conductive resin composition or a molding material of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 9/04 C08K 9/04 C08L 69/00 C08L 69/00 H01B 1/20 H01B 1/20 Z 1 / 24 1/24 Z // B29K 67:00 B29K 67:00 69:00 69:00 105: 12 105: 12 F term (reference) 4F071 AA43 AA45 AA50 AB03 AD01 AE15 AH12 BB05 4F201 AA24 AA25 AA28 AB13 AB18 AB25 AB28 AE03 AH17 AH25 AH33 BA02 BC02 BC15 BC37 BD04 BL44 BL45 4J002 CF07W CF18W CG00X CG01X DA026 FA046 FB076 FB266 FD116 5G301 DA03 DA05 DA10 DA20 DA53 DA60

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]: polybutylene terephthalate resin and / or liquid crystal polyester resin. Component [C]: polycarbonate 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]: a water-soluble ester-based resin and / or a water-soluble ether-based 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.