JP2011144270A - Electroconductive resin composition and method for producing electroconductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroconductive resin composition forming an electroconductive film having a good appearance with little reduction of electroconductivity even after stretching at a high ratio, and to provide a method for producing the electroconductive film with good productivity. <P>SOLUTION: The resin composition includes: a thermoplastic resin (A); carbon black (B); and a resin (C). The glass transition temperature of the resin (C) is lower than that of the thermoplastic resin (A), and the interfacial free energy between the carbon black (B) and resin (C) is lower than that between the carbon black (B) and thermoplastic resin (A). Furthermore, the interfacial free energy between the carbon black (B) and resin (C) is 0-50 mN/m. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a conductive resin composition and a method for producing a biaxially stretched conductive film.

  Conductive resin compositions obtained by imparting conductivity to a thermoplastic resin have been developed in various fields such as electronic component packaging container applications, intermediate transfer belts for image forming apparatuses, charging (static charge) brush applications, and clothing applications.

  And as a conductive substance, carbon-based materials such as carbon black, carbon fiber, metal oxides such as tin oxide, titanium oxide, antimony oxide, indium oxide, metal powder such as copper, silver, nickel are known, Among these, carbon black that is inexpensive and has good conductivity is generally used as a conductive agent.

  By the way, as a method for imparting conductivity to a film made of a thermoplastic resin, a coating method or a kneading method is mainly known.

  The coating method is a method of forming a film by applying a coating agent containing a conductive material such as carbon black on the film surface. According to this method, it is difficult to completely avoid pinholes and coating unevenness, and the quality performance is low, and it tends to be unstable. Moreover, since a solvent-type coating agent having a strong substrate tackiness is used, the substrate is often deteriorated. Furthermore, there are problems in that the manufacturing process is complicated and the manufacturing cost is high compared to the kneading method.

  On the other hand, the kneading method is a method of kneading into a thermoplastic resin in which a conductive material such as carbon black is melted and molding. According to this method, there are advantages that the manufacturing process is relatively simple and the manufacturing cost is low compared to the coating type, but in order to achieve high conductivity, it is necessary to add a large amount of conductive material. Therefore, there is a problem that it is difficult to obtain a molded article having a good appearance.

  In addition, a stretched film obtained by stretching a film made of a thermoplastic resin has excellent mechanical properties and optical characteristics, and thus is used in various fields as a high-value-added film. However, the conductivity of the film imparted with carbon black is reduced by this stretching. The reason for this is considered to be that the conductive network structure by carbon black dispersed in the resin is destroyed by stretching the film.

  In order to solve the above-described problem, a conductive resin composition obtained by blending a carbon black with an unsaturated carboxylic acid or derivative added to a thermoplastic resin is disclosed (for example, see Patent Document 1). However, only the surface resistivity of the film under low magnification (5 times) stretching is described, and satisfactory conductivity is not obtained. In addition, when an unsaturated carboxylic acid is attached to carbon black, an organic solvent such as acetone or toluene is used, which is problematic in terms of environment. Furthermore, since carbon black to which an unsaturated carboxylic acid derivative is added is used, there are problems in that the manufacturing process becomes complicated and the manufacturing cost increases.

  Moreover, in order to solve the said problem, the molded object using the semiconductive resin composition which disperse | distributes carbon fiber in matrix resin is disclosed (for example, refer patent document 2). However, since carbon fibers generally have a large specific surface area and high cohesive energy, it is difficult to suppress the coagulation. In addition, carbon fibers with a specific surface area and aspect ratio are used to suppress the aggregation of carbon fibers, but there are still many agglomerates present in the molded products, and molded products with good appearance have not been obtained. Absent. In addition, since a part of the carbon fiber is broken during kneading with the resin, a molded article having stable conductivity has not been obtained.

JP-A-5-81925 JP 2009-126985 A

  An object of the present invention is to provide a conductive resin composition capable of forming a conductive film having a good appearance and having a small decrease in conductivity even after stretching at a high magnification, and a method for producing a conductive film having good productivity.

The present inventors have intensively studied to solve the above problems.
That is, the first invention of the present invention is a resin composition comprising a thermoplastic resin (A), carbon black (B), and resin (C),
The glass transition temperature of the resin (C) is lower than the glass transition temperature of the thermoplastic resin (A),
The interface free energy between the carbon black (B) and the resin (C) is lower than the interface free energy between the carbon black (B) and the thermoplastic resin (A),
It is related with the conductive resin composition characterized by the interface free energy of carbon black (B) and resin (C) being 0-50 mN / m.

  2nd invention of this invention is related with the conductive resin composition of the said invention characterized by the DBP oil absorption of carbon black (B) being 30-750 ml / 100g.

  A third invention of the present invention relates to the conductive resin composition of the above invention, wherein the resin (C) is a thermoplastic elastomer or polyethylene.

  4th invention of this invention is related with the electroconductive masterbatch characterized by including the conductive resin composition of the said invention.

  5th invention of this invention is related with the electroconductive film formed using the conductive resin composition of the said invention, and extending | stretched.

  The sixth invention of the present invention is a step (1) of melt-kneading a resin composition containing the conductive resin composition of the above invention, then a step (2) of forming a film, and further stretching the film. It is related with the manufacturing method of the electroconductive film characterized by including a process (3).

  7th invention of this invention is related with the manufacturing method of the electroconductive film of the said invention characterized by biaxially stretching a film in the said process (3).

  The eighth invention of the present invention relates to the method for producing a conductive film of the above invention, wherein, in the step (3), the draw ratio of the film is 1.5 to 25 times in terms of area ratio.

  The ninth invention of the present invention relates to a conductive film obtained by the production method of the above invention.

A tenth aspect of the present invention relates to a conductive film, wherein the conductive film of the present invention has a surface resistivity of 1 × 10 ⁷ Ω / □ or less.

  According to the present invention, a conductive resin composition with little decrease in conductivity even after high-stretching, a conductive film with good appearance using the same, and a method for producing a conductive film with good productivity can be realized.

The conductive resin composition of the present invention comprises a thermoplastic resin (A), carbon black (B), and resin (C). The conductive resin composition is preferably used for forming a biaxially stretched conductive film. In the present invention, the resin (C) having a glass transition temperature lower than that of the thermoplastic resin (A) is used, and the free energy of the interface between the carbon black (B) and the resin (C) is higher than that of the carbon black (B) and the heat. It is important that the interface free energy is lower than the interface free energy with the plastic resin (A) and the interface free energy between the carbon black (B) and the resin (C) is 0 to 50 mN / m. Thereby, since carbon black (B) in a conductive resin composition is unevenly distributed in resin (C), the distance between carbon black (B) can be shortened. And when the conductive resin composition of the present invention is used for a biaxially stretched conductive film, compared with the case of simply kneading carbon black (B) into the thermoplastic resin (A), Since the conductive network structure by carbon black (B) is hard to be destroyed at the time of stretching, a decrease in conductivity after stretching of the conductive film can be minimized.
Hereinafter, the present invention will be specifically described.

<Thermoplastic resin (A)>
In the present invention, the thermoplastic resin (A) is not particularly limited as long as it is a resin that can be molded by heating and melting. For example, polyolefin resin such as polyethylene resin and polypropylene resin, polystyrene resin, polyphenylene ether Resin, acrylonitrile-butadiene-styrene copolymer resin, polycarbonate resin, polyamide resin, polyacetal resin, polyester resin, polyvinyl chloride resin, polymethyl methacrylate resin, polyetherimide resin, and mixtures thereof. As a particularly preferred thermoplastic resin, it is inexpensive and excellent in workability, and is widely used for electronic parts packaging materials, home appliances, automobile parts, fibers, etc. due to its characteristics such as heat resistance, mechanical properties, chemical resistance, and light weight. A polypropylene is mentioned.

  The thermoplastic resin (A) preferably has a melt flow rate (hereinafter referred to as MFR) (measured at 230 ° C. under a load of 2.16 kg according to JIS K 7210) of 0.1 to 100 g / 10 min. Preferably it is 1-50 g / 10min. If the MFR is less than 0.1 g / 10 min, the melt viscosity of the conductive resin composition is remarkably increased and the moldability of the film may be deteriorated. When the MFR exceeds 100 g / 10 min, it is difficult to melt and disperse the carbon black (B) in the resin, and a film having a good appearance may not be obtained.

  In the present invention, the amount of the thermoplastic resin (A) used is preferably 40 to 90% by weight, more preferably 47 to 85% by weight, particularly 55 to 80% by weight, in 100% by weight of the conductive resin composition. preferable. If it is less than 40% by weight, the effect of improving the mechanical properties by stretching the film may not be sufficiently exhibited. Moreover, the heat resistance of a film falls and a film may be broken at the time of extending | stretching. On the other hand, when the amount is more than 90% by weight, it becomes difficult to disperse the carbon black (B) and the resin (C), so that a film having stable conductivity may not be obtained.

  Moreover, it is preferable that the usage-amount of the said thermoplastic resin (A) is large compared with the usage-amount of resin (C). When the amount of the thermoplastic resin (A) used is small compared to the amount of the resin (C) used, the distance between the carbon blacks (B) unevenly distributed in the resin (C) is that of the thermoplastic resin (A). Since the amount used is longer than the amount used for the resin (C), the conductivity may decrease too much after the film is stretched.

<Carbon black (B)>
In the present invention, the carbon black (B) is preferably in the form of particles having an aspect ratio in the range of 1 to 5. Specifically, for example, when a synthesis gas containing hydrogen and carbon monoxide is produced by partially oxidizing hydrocarbons such as ketjen black, acetylene black, furnace black, channel black and naphtha in the presence of hydrogen and oxygen. And carbon black produced as a by-product, or carbon black, graphite, carbon nanotube, fullerene and the like obtained by oxidizing or reducing it. Particularly preferred carbon blacks include Denka black and Ketjen black. Carbon black having an average particle size of 50 nm or less is preferably used. In the present invention, the aspect ratio means that when the carbon black (B) is in a particulate form, the major axis length of the spherical component constituting the carbon black structure is divided by the minor axis length of the spherical component. Refers to the value. On the other hand, when carbon black (B) is a fibrous form, the value which divided the fiber length by the fiber diameter is pointed out.

Furthermore, the DBP oil absorption of the carbon black (B) is preferably 30 to 750 ml / 100 g, and more preferably 100 to 400 ml / 100 g. Carbon black having a DBP oil absorption of less than 30 ml / 100 g has good melt dispersion in the resin, but the intended conductivity may not be obtained. Carbon black with a DBP oil absorption exceeding 750 ml / 100 g provides the desired conductivity, but it is difficult to melt and disperse in the resin, leaving an undispersed agglomerate of carbon black, which is stable during film formation and stretching. Tend to decrease significantly.
In the present invention, the DBP oil absorption is a measure of a complex agglomeration form (structure) due to chemical or physical bonding between the carbon black particles, and the dibutyl phthalate (DBP) that can be included per 100 g of carbon black. The larger the numerical value (ml), the higher the carbon black, the better the conductive performance.

  Furthermore, in the present invention, it is necessary that the interface free energy between the carbon black (B) and the resin (C) is lower than the interface free energy between the carbon black (B) and the thermoplastic resin (A). If the interfacial free energy between the carbon black (B) and the resin (C) is higher than the interfacial free energy between the carbon black (B) and the thermoplastic resin (A), the conductivity may be reduced too much after the film stretching. . This is presumably because the carbon black (B) tends to be unevenly distributed in the thermoplastic resin (A) compared to the resin (C), and the formation of a conductive network structure in the resin composition is insufficient.

  Furthermore, in the present invention, the interface free energy between the carbon black (B) and the resin (C) needs to be 0 to 50 mN / m. More preferably, it is 0-40 mN / m, Most preferably, it is 0-30 mN / m. When the interface free energy between the carbon black (B) and the resin (C) exceeds 50 mN / m, the dispersion of the carbon black (B) into the resin (C) tends to deteriorate. As a result, since it becomes difficult to form a conductive network structure in the resin composition, the conductivity may be excessively lowered after the film is stretched.

  When a plurality of types of carbon black (B) are used, the interfacial free energy between carbon black (B) and resin (C) is lower than the interfacial free energy between carbon black (B) and thermoplastic resin (A), It is preferable that the interface free energy of carbon black (B) and resin (C) is 50 mN / m or less, respectively. If even one type does not satisfy the above conditions, the dispersion of the carbon black (B) into the resin (C) tends to deteriorate. As a result, since it becomes difficult to form a conductive network structure in the resin composition, the conductivity may be excessively lowered after the film is stretched.

Further, in order to adjust the interface free energy, a surface treatment of carbon black may be performed.
In the present invention, the interfacial free energy is a factor representing the affinity between samples, and is calculated from the surface free energy of each sample using the extended Fowkes equation. It shows that the affinity between samples is so high that the value of interface free energy is small.
The surface free energy of each sample was measured using an automatic contact angle meter (Kyowa Interface Science Co., Ltd., DCA-VZ) and surface free energy analysis software (Kyowa Interface Science Co., Ltd., EG-11). Specifically, first, using the contact angle meter (environmental temperature: 23 ° C., 50% RH), the standard solution was dropped onto the sample surface to measure the contact angle. Three types of liquids are required as a standard liquid: a nonpolar liquid, a polar liquid, and a hydrogen bonding liquid. In the present invention, hexadecane is used as the nonpolar liquid, methylene iodide is used as the polar liquid, and water is used as the hydrogen bonding liquid. The measured value was used.
Next, using the surface free energy analysis software, the surface free energy of each sample was analyzed based on the measurement result of the obtained contact angle. Finally, based on the measurement result of the obtained surface free energy, the interface free energy between each sample was calculated using the extended Fowkes formula (Journal of Japan Adhesion Association, 8 (3), 131 (1972)).

  In the present invention, the amount of carbon black (B) used is preferably 5 to 30% by weight, more preferably 5 to 28% by weight, and particularly preferably 5 to 25% by weight, in 100% by weight of the conductive resin composition. . If it is less than 5% by weight, good conductivity may not be obtained during film formation. On the other hand, when the amount is more than 30% by weight, poor dispersion of carbon black occurs, and a film having a good appearance may not be obtained. In addition, clogging due to the undispersed agglomerates of carbon black may occur during extrusion or film forming, and production efficiency may deteriorate.

<Resin (C)>
In the present invention, the resin (C) is preferably a thermoplastic elastomer or polyethylene. It is preferable to use a resin that is different from the resin used for the thermoplastic resin (A) and incompatible with the thermoplastic resin (A). Further, the glass transition temperature of the resin (C) is lower than the glass transition temperature of the thermoplastic resin (A), and the interface free energy between the carbon black (B) and the resin (C) is carbon black (B). It is necessary that the interface free energy is lower than the interface free energy with the thermoplastic resin (A) and the interface free energy between the carbon black (B) and the resin (C) is 50 mN / m or less.

  A thermoplastic elastomer refers to a material that softens by heating and exhibits fluidity, but exhibits rubber elasticity at room temperature. The molecular structure consists of a soft segment that exhibits rubber elasticity and a hard segment that flows at high temperatures but prevents plastic deformation at room temperature, and the hard segments associate or aggregate to form a microphase separation structure. . For example, olefin elastomers such as ethylene-propylene copolymer (EPM) and ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer (SBS) and styrene-ethylene-butadiene copolymer (SEBS). ) -Based styrene elastomers, silicon elastomers, nitrile elastomers, butadiene elastomers, urethane elastomers, nylon elastomers, ester elastomers, fluorine elastomers, and reactive sites (double bonds, anhydrous carboxyl groups). Etc.) may be mentioned. These may be used alone or in combination of two or more.

  The thermoplastic elastomer can also include a so-called crosslinked rubber in which molecular chains are crosslinked with sulfur or the like. Examples of the crosslinked rubber include natural rubber, synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene copolymer rubber (NBR), and butyl rubber (IIR). ), Cross-linked products such as halogenated butyl rubber, urethane rubber, silicone rubber, fluorine rubber, and polysulfide rubber. These may be used alone or in combination of two or more.

  In the present invention, polyethylene means high density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and ultra low density polyethylene having a density of less than 0.90 ( VLDPE) and copolymers of two or more compounds selected from ethylene and other α-olefins, unsaturated carboxylic acids or derivatives thereof, such as ethylene-butene-1 copolymers, ethylene-acrylic acid copolymers , Ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, and the like.

The glass transition temperature (hereinafter also referred to as Tg) of the resin (C) in the present invention needs to be lower than the Tg of the thermoplastic resin (A), and preferably with respect to the Tg of the thermoplastic resin (A). The temperature is 10 ° C. or more, more preferably 20 ° C. or more. When the Tg of the resin (C) is higher than the Tg of the thermoplastic resin (A) or the Tg of the resin (C) is lower than the Tg of the thermoplastic resin (A) by less than 10 ° C., the conductivity after stretching is There is a tendency to decrease. This is presumably because the carbon black (B) is not sufficiently unevenly distributed in the resin (C), and a sufficiently developed conductive network structure cannot be formed in the resin composition.
In the present invention, Tg was measured according to JIS K 7121 in a nitrogen atmosphere using a differential scanning calorimeter (DSC220, manufactured by Seiko Instruments Inc.). A sealed sample container having a capacity of 50 μl was packed with 15 to 20 mg of sample, and the measurement was performed at a heating rate of 10 ° C./min. Specifically, in the portion showing the step-like change of the obtained DSC curve, a straight line equidistant from the extended straight line of each baseline in the vertical axis direction and the curve of the step-like change portion of the glass transition The temperature at the intersecting point was defined as Tg. When there are a plurality of Tg, the lowest temperature value is adopted in the present invention.

  It is preferable to use the resin (C) in an amount that does not impair the properties of the conductive film of the present invention. That is, 5 to 30% by weight is preferable, 100 to 25% by weight is more preferable, and 15 to 20% by weight is particularly preferable in 100% by weight of the conductive resin composition. When the amount of the resin (C) used is less than 5% by weight, the conductivity may be lowered too much after the film is stretched. This is presumably because the proportion of carbon black (B) unevenly distributed in the resin (C) decreases, and a sufficiently developed conductive network structure cannot be formed in the film. On the contrary, when the addition amount of resin (C) exceeds 30 weight%, the heat resistance of a film will fall and a film may be broken at the time of extending | stretching.

<Conductive resin composition>
The conductive resin composition of the present invention is a mixture of a melt-kneaded product obtained by mixing and melting and kneading the above components (A) to (C) and a diluted resin, a so-called master batch or the above (A) to (C ) A melt-kneaded product obtained by mixing and melt-kneading the components, so-called compound form, is preferred.

  In addition to the main components (A) to (C), the conductive resin composition may be added with one or more types within a range that does not affect the moldability, blocking properties, and conductivity of the conductive film. You may mix an agent suitably. There are no particular limitations on the additive used, for example, various commonly used leveling agents, dyes, pigments, pigment dispersants, ultraviolet absorbers, antioxidants, viscosity modifiers, light stabilizers, metal inertness Agent, peroxide decomposer, filler, reinforcing agent, plasticizer, lubricant, anticorrosive agent, rust inhibitor, emulsifier, mold bleaching agent, fluorescent whitening agent, organic flameproofing agent, inorganic flameproofing agent, dripping Examples thereof include an inhibitor, a melt flow modifier, and an antistatic agent.

<Conductive film>
The conductive film of the present invention is a conductive film formed using the conductive resin composition and stretched. The method for producing a conductive film includes a step (1) of melt-kneading a resin composition containing a conductive resin composition, a step (2) for forming a film, and a step (3) for further stretching the film. It is preferable to contain.
Hereinafter, each step will be specifically described.

  First, the step (1) of melt-kneading a resin composition containing a conductive resin composition will be described. In the present invention, the method of melt kneading the resin composition containing the conductive resin composition is not particularly limited as long as it is a method of melt kneading at a temperature higher than the melting points of the thermoplastic resin (A) and the resin (C). The apparatus used for melt kneading is not particularly limited, and examples thereof include known melt kneading apparatuses, such as a single screw extruder, a twin screw extruder, a Banbury mixer, etc., but have a high dispersion capacity and production. Therefore, kneading with a twin screw extruder is desirable. As the screw element used in the twin screw extruder, it is preferable to use a screw element with reduced shearing in order to prevent agglomeration of carbon black and destruction of the structure. A pressure kneader that does not apply a high shearing force and can achieve dispersion over time is also preferably used.

  At this time, the melt-kneading temperature varies depending on the resin composition, but when crystalline polypropylene is used as the thermoplastic resin (A), it is preferably carried out at 180 to 230 ° C, more preferably 200 to 220 ° C. When the melt kneading temperature is less than 180 ° C., the thermoplastic resin (A) is not sufficiently plasticized and the kneading of the thermoplastic resin (A) and the carbon black (B) (or the resin (C)) is insufficient. May be. On the contrary, when it exceeds 230 degreeC, deterioration of a thermoplastic resin (A) and resin (C) may progress more than needed, and film strength may fall.

The order of melt-kneading the resin composition containing the conductive resin composition is as follows. First, (A) and (B) are mixed, melt-kneaded, and then (C) is added and further melt-kneaded. Alternatively, (B) and (C) may be first mixed and melt kneaded, then (A) may be added and further melt kneaded, or (A), (B) , (C) may be mixed simultaneously and melt-kneaded.
Further, when using a plurality of types (B), first, (B) one type and (A) or (C) are mixed, melt-kneaded to prepare a melt-kneaded product, and then a plurality of types (B) ( A) or (B) (C) the melt-kneaded material may be mixed and melt-kneaded again.

  Next, step (2) for forming a conductive film will be described. The method for forming the conductive film used in the present invention is not particularly limited, and examples thereof include a melt extrusion method such as a T-die method and an inflation method, a calendar method, and the like.

  The formation temperature of the conductive film of the present invention varies depending on the resin composition, but when crystalline polypropylene is used as the thermoplastic resin (A), the temperature may be the same as the temperature at the time of melt kneading of the conductive resin composition. it can.

  Finally, the step (3) of stretching the conductive film will be described. The method for stretching the conductive film used in the present invention is not particularly limited. For example, the wet uniaxial stretching method, the dry uniaxial stretching method, the tenter sequential biaxial stretching method, the tenter simultaneous biaxial stretching method, the tubular two Examples thereof include an axial stretching method.

  Moreover, although extending | stretching temperature changes with resin compositions, when crystalline polypropylene is used as a thermoplastic resin (A), it is 120-150 degreeC normally, Preferably it is performed at 125 to 145 degreeC. If it is out of the above range, it tends to be difficult to stretch the film uniformly.

The draw ratio of the conductive film used in the present invention is preferably 1.5 to 25 times, and more preferably 4 to 16 times. In the present invention, the draw ratio is obtained by multiplying the unstretched film by the ratio when stretched in the flow direction (hereinafter also referred to as MD direction) and the ratio when stretched in the vertical direction (hereinafter also referred to as TD direction). Insert the value (unit: times).
If the draw ratio is less than 1.5, it is difficult to obtain a film having sufficient mechanical properties. On the other hand, when the draw ratio exceeds 25 times, the conductivity may be greatly lowered after drawing. In addition, the film may be damaged during stretching.
Further, in the case of biaxial stretching, the stretching ratio in each of the MD and TD directions is preferably more than 1 and not more than 5 times. If the draw ratio in each direction of MD and TD exceeds 5 times, the conductivity in this direction may be greatly lowered after drawing. In addition, the film may be damaged during stretching.

Moreover, the surface resistivity of the conductive film of the present invention obtained by the above production method is preferably 1 × 10 ⁷ Ω / □ or less, more preferably 1 × 10 ⁶ Ω / □ or less. When the surface resistivity of the conductive film after stretching exceeds 1 × 10 ⁷ Ω / □, when the film is used as various members, a sufficient antistatic effect may not be exhibited.

  The molded article of the present invention is excellent in appearance and exhibits excellent conductivity on its surface, and is suitable for films, sheets, containers, tapes, flat yarns and the like. Therefore, it is effective as a packaging body for precision electronic parts and electronic devices, a container such as a tray, various protective members, a flexible container material, and a magnetic recording tape.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples without departing from the technical idea of the present invention.

  Table 1 shows the glass transition temperature of the thermoplastic resin (A) and the resin (C) used in Examples and Comparative Examples, and the interfacial free energy between the carbon black (B) and the thermoplastic resin (A) or the resin (C). Summarized.

  In addition, Tables 2 and 3 show the blends of the conductive resin compositions in Examples and Comparative Examples.

Example 1
(1) Melt-kneading PP part (thermoplastic resin (A)) 59.9 parts by weight Denka black granular product (carbon black (B)) 40 parts by weight, Irganox 1010 (antioxidant) 0.1 Parts by weight are supplied to a twin screw extruder having a screw diameter of 32 mm and L / D (screw diameter / screw length) = 45.75, and melt kneaded under the conditions of a cylinder temperature of 200 ° C. to 230 ° C. and a screw rotation speed of 230 rpm. A carbon master batch (CMB-1) was produced by extrusion.
With respect to 52.5 parts by weight of the above CMB-1, 15 parts by weight of SBS (A) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dry blended. This mixture is supplied to a twin screw extruder having a screw diameter of 30 mm and L / D (screw diameter / screw length) = 42, and melt-kneaded and extruded under conditions of a cylinder temperature of 200 ° C. to 220 ° C. and a screw rotation speed of 230 rpm. Conductive resin composition (weight ratio of each component: thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant) : 0.05% by weight).

(2) Formation of film The conductive resin composition is supplied to a T-die extruder (Toyo Seiki Seisakusho, Labo Plast Mill), Lip opening 0.35 mm 120 mesh, cylinder temperature 200 ° C to 230 ° C. A conductive film having a thickness of 0.1 mm was produced by melt-kneading and extruding under the conditions of ° C and a screw rotation speed of 100 rpm.

(3) Stretching of film Simultaneously biaxial stretching (drawing ratio: 9) using the biaxial stretching device (Toyo Seiki Seisakusho, EX-10B) was conducted on the conductive film under the conditions of 125 ° C and a stretching speed of 500 mm / min. Double: Stretch ratio in MD direction: 3 times, Stretch ratio in TD direction: 3 times) to obtain a conductive biaxially stretched film.

(4) Evaluation of film The conductive film was evaluated by the following method. The evaluation results are shown in Table 4.

[Production stability]
At the time of film forming, ◎ (particularly good) when the increase value of the resin pressure in the molding machine is less than 3 MPa after 1 hour ○ (good) when 3 MPa or more and less than 5 MPa △ (somewhat when 5 MPa or more and less than 7 MPa) Defect), the case of 7 MPa or more was evaluated as x (defect). In the case of 7 MPa or more, since the resin temperature tends to increase due to clogging of the mesh and the resin deterioration tends to progress (and the discharge tends to be unstable and a film with a constant thickness cannot be obtained), remove the T die head. It is necessary to replace the mesh, and production efficiency is particularly reduced.

[appearance]
The number of bumps per 10 cm square (100 cm ² ) of the film before stretching was counted and evaluated. The protrusions were various shapes such as circles, ellipses, and squares, and the longest length of the plane of the film was a projection having a length of 0.1 mm or more. ◎ (particularly good) when the number is less than 50, ○ (good) when the number is 50 or more and less than 75, △ (somewhat bad) when the number is 75 or more and less than 100, and × when the number is 100 or more (Defect).

[Conductivity]
About the film before extending | stretching and a film after extending | stretching, surface resistance is measured using a surface resistance meter (Simco Japan Co., Ltd. work surface tester ST-3, applied voltage 15V or less) in a constant temperature and humidity chamber (23 degreeC, 50% RH). It was measured. In addition, the measurement measured 3 times per sample using the film left still for one day in a constant temperature and humidity chamber, and calculated | required the average value.

(Example 2)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of SBS (I) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 3)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of SEBS (A) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

Example 4
52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of SEBS (I) (resin (C)), and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dried. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 5)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of polyurethane (A) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 6)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of polyurethane (I) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 7)
52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of polyether (A) (resin (C)), and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Conductive resin composition by dry blending (weight ratio of each component: thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant : 0.05% by weight) except that the conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 8)
52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of polyether (I) (resin (C)), and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Conductive resin composition by dry blending (weight ratio of each component: thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant : 0.05% by weight) except that the conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

Example 9
Dry blend of 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of EPDM (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 10)
Dry blend of 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of LDPE (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 11)
Dry 37.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of SBS (A) (resin (C)) and 47.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 69.96 wt%, carbon black (B): 15 wt%, resin (C): 15 wt%, antioxidant: Except for producing 0.04% by weight, a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 12)
Conductive by dry blending 75 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of SBS (A) (resin (C)) and 10 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Resin composition (weight ratio of each component Thermoplastic resin (A): 54.92 wt%, carbon black (B): 30 wt%, resin (C): 15 wt%, antioxidant: 0.08 wt% %) Was produced in the same manner as in Example 1, except that biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 13)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 10 parts by weight of SBS (A) (resin (C)) and 37.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 68.95% by weight, carbon black (B): 21% by weight, resin (C): 10% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 14)
Dry 52.5 parts by weight of CMB-1 obtained in Example 1, 25 parts by weight of SBS (A) (resin (C)) and 22.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 53.95% by weight, carbon black (B): 21% by weight, resin (C): 25% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 15)
15 parts by weight of Ketjen Black EC300-J (carbon black (B)) and 0.07 parts by weight of Irganox 1010 (antioxidant) with respect to 84.93 parts by weight of PP (thermoplastic resin (A)) Is supplied to a twin screw extruder having a screw diameter of 32 mm and L / D (screw diameter / screw length) = 45.75, and melt kneaded and extruded under conditions of a cylinder temperature of 200 ° C. to 230 ° C. and a screw speed of 230 rpm. A carbon master batch (CMB-2) was produced.
Dry blend of 15 parts by weight of SBS (A) (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin with respect to 66.7 parts by weight of CMB-2. Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 16)
Dry 66.7 parts by weight of CMB-2 obtained in Example 15, 15 parts by weight of polyurethane (A) (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 17)
65.7 parts by weight of CMB-2 obtained in Example 15, 15 parts by weight of LDPE (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dry blended. Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 18)
40 parts by weight of # 650B (carbon black (B)) and 0.1 parts by weight of Irganox 1010 (antioxidant) are added to 59.9 parts by weight of PP (thermoplastic resin (A)), and the screw diameter is 32 mm. , L / D (screw diameter / screw length) = 45.75, supplied to a twin screw extruder, melt kneaded and extruded under the conditions of a cylinder temperature of 200 ° C. to 230 ° C. and a screw rotation speed of 230 rpm, and formed into a pellet, A carbon master batch (CMB-3) was produced.
Dry blend of 52.5 parts by weight of CMB-3 with 15 parts by weight of SBS (A) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Example 19)
Dry 52.5 parts by weight of CMB-3 obtained in Example 18, 15 parts by weight of polyurethane (A) (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Example 20)
52.5 parts by weight of CMB-3 obtained in Example 18, 15 parts by weight of LDPE (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dry blended. Conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: 0.05 A conductive film was produced in the same manner as in Example 1 except that (% by weight) was produced, and biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 1)
A conductive resin composition (each component) was dry blended with 52.5 parts by weight of CMB-1 obtained in Example 1 and 47.5 parts by weight of PP (thermoplastic resin (A)) as a diluent resin. The conductive ratio is the same as in Example 1 except that a thermoplastic resin (A): 78.95% by weight, carbon black (B): 21% by weight, antioxidant: 0.05% by weight) was prepared. A conductive film was prepared and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 2)
Conductive resin composition (weight ratio of each component) by dry blending 25 parts by weight of PP (thermoplastic resin (A)) as a dilution resin to 75 parts by weight of CMB-1 obtained in Example 1 A conductive film was prepared in the same manner as in Example 1 except that the plastic resin (A): 69.92 wt%, carbon black (B): 30 wt%, and antioxidant: 0.08 wt% were prepared. Then, biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 3)
Conductive resin composition (each component) was obtained by dry blending 66.7 parts by weight of CMB-2 obtained in Example 15 with 33.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. The weight ratio of the thermoplastic resin (A): 89.95% by weight, carbon black (B): 10% by weight, antioxidant: 0.05% by weight) was conducted in the same manner as in Example 1 except that it was produced. A conductive film was prepared and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 4)
Conductive resin composition (each component) was dry blended with 52.5 parts by weight of CMB-3 obtained in Example 18 and 47.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin. The conductive ratio is the same as in Example 1 except that a thermoplastic resin (A): 78.95% by weight, carbon black (B): 21% by weight, antioxidant: 0.05% by weight) was prepared. A conductive film was prepared and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 5)
With respect to 52.5 parts by weight of CMB-1 obtained in Example 1, 15 parts by weight of PS (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dried. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 6)
With respect to 66.7 parts by weight of CMB-2 obtained in Example 15, 15 parts by weight of PS (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dried. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 7)
With respect to 52.5 parts by weight of CMB-3 obtained in Example 18, 15 parts by weight of PS (resin (C)) and 32.5 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dried. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 63.95% by weight, carbon black (B): 21% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 8)
With respect to 84.93 parts by weight of PP (thermoplastic resin (A)), 15 parts by weight of VGCF (carbon black (B)) and 0.07 parts by weight of Irganox 1010 (antioxidant) have a screw diameter of 32 mm, L / D (screw diameter / screw length) = 45.75, supplied to a twin screw extruder, melt kneaded and extruded under the conditions of a cylinder temperature of 200 ° C. to 230 ° C. and a screw rotation speed of 230 rpm, and formed into a pellet, carbon A master batch (CMB-4) was produced.
Conductive resin composition (weight ratio of each component thermoplastic resin) by dry blending 33.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin with respect to 66.7 parts by weight of CMB-4 (A): 89.95% by weight, carbon black (B): 10% by weight, resin antioxidant: 0.05% by weight) A conductive film was prepared in the same manner as in Example 1. Biaxial stretching was performed. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 9)
15 parts by weight of SBS (A) (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin with respect to 66.7 parts by weight of CMB-4 obtained in Comparative Example 8 And a conductive resin composition (weight ratio of each component: thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, oxidation A conductive film was prepared and biaxially stretched in the same manner as in Example 1 except that the inhibitor: 0.05% by weight) was prepared. The evaluation results of the conductive film are shown in Table 4.

(Comparative Example 10)
With respect to 66.7 parts by weight of CMB-4 obtained in Comparative Example 8, 15 parts by weight of PS (resin (C)) and 18.3 parts by weight of PP (thermoplastic resin (A)) as a dilution resin were dried. Blended conductive resin composition (weight ratio of each component Thermoplastic resin (A): 74.95% by weight, carbon black (B): 10% by weight, resin (C): 15% by weight, antioxidant: Except for producing 0.05 wt%), a conductive film was produced in the same manner as in Example 1 and biaxially stretched. The evaluation results of the conductive film are shown in Table 4.

[Thermoplastic resin (A)]
PP: Prime polymer Co., Ltd. Crystalline polypropylene resin J105G MFR = 9 g / 10 min

[Carbon black (B)]
Denka Black (granular product) Particle size = 35 nm DBP oil absorption = 160 ml / 100 g Aspect ratio≈1
Ketjen Black International Co., Ltd. Ketjen Black EC-300J Particle size = 40 nm DBP oil absorption = 365 ml / 100 g Aspect ratio≈1
Mitsubishi Chemical Corporation # 650B Particle size = 22 nm DBP oil absorption = 114 ml / 100 g Aspect ratio≈1
Showa Denko Co., Ltd. VGCF (Gas phase grown carbon fiber) Fiber diameter = 150 nm Fiber length = 10-20 μm Aspect ratio = 10-500

[Resin (C)]
SBS (A): Asahi Kasei Chemicals Co., Ltd. Styrene-butadiene thermoplastic elastomer Toughprene 126S
SBS (b): Asahi Kasei Chemicals Co., Ltd. Styrene-butadiene thermoplastic elastomer Asaflex 805
SEBS (A): Asahi Kasei Chemicals Co., Ltd. Hydrogenated styrene-ethylene-butadiene thermoplastic elastomer Tuftec H1043
SEBS (b): Asahi Kasei Chemicals Corporation hydrogenated styrene-ethylene-butadiene thermoplastic elastomer Tuftec H1221
Polyurethane (A): DIC Bayer Polymer Co., Ltd. Polyurethane-based thermoplastic elastomer Pandex T-2190
Polyurethane (I): DIC Bayer Polymer Co., Ltd. Polyurethane-based thermoplastic elastomer Pandex T-8190
Polyether (A): Sanyo Chemical Industries, Ltd. Polyether-based thermoplastic elastomer Pelestat 230
Polyether (I): Sanyo Chemical Industries, Ltd. Polyether-based thermoplastic elastomer Pelestat 6500
EPDM: JSR Corporation Ethylene-propylene-diene rubber EP57P
LDPE: Asahi Kasei Chemicals Corporation Low density polyethylene Suntech LD M2270
PS: Nippon Polystyrene Co., Ltd. Polystyrene 679

[Antioxidant]
Ciba Specialty Chemicals Co., Ltd. Irganox 1010

From the results of Table 4, the comparative example shows that when the resin (C) is not added (Comparative Examples 1 to 4), the surface resistivity of the biaxially stretched film is about 1 × 10 ¹² Ω / □, and is conductive by stretching. The characteristics were greatly reduced. At this time, the production stability was good to somewhat poor, and the appearance was slightly poor to poor. Also when the resin (C) showing a glass transition temperature higher than that of the thermoplastic resin (A) is used (Comparative Examples 5 to 7), the surface resistivity of the biaxially stretched film is 1 × 10 ¹² Ω. / □ indicates that the conductivity was greatly reduced by stretching. At this time, the production stability was slightly poor to poor, and the appearance was poor. Further, when VGCF (vapor phase carbon fiber) is used as the carbon black (B) (Comparative Examples 8 to 10), both the production stability and the appearance are poor, and the carbon fiber body dispersed aggregate is the starting point at the time of stretching. As the film was torn, it was impossible to measure the surface resistivity.
On the other hand, since an Example is a conductive film obtained from the conductive resin composition containing thermoplastic resin (A), carbon black (B), and resin (C), it is conductive even after biaxial stretching. (1 × 10 ⁷ Ω / □ or less) and the appearance and production stability were both good (Examples 1 to 10). Also, when the amount of carbon black (B) used is changed (Example 11 or 12) or when the amount of resin (C) used is changed (Example 13 or 14), or the type / grade of carbon black (B) Even in the case where the film thickness was changed (Examples 15 to 20), the film after biaxial stretching maintained the conductivity (1 × 10 ⁷ Ω / □ or less), and both the appearance and the production stability were good. It was.
From the above, according to the present invention, it is possible to provide a conductive resin composition capable of forming a conductive film having a good appearance and having a low conductivity decrease even after high-stretch stretching, and a method for producing a conductive film with good productivity. Therefore, the industrial utility value of the present invention is extremely large.

Claims (10)

A resin composition comprising a thermoplastic resin (A), carbon black (B), and resin (C),
The glass transition temperature of the resin (C) is lower than the glass transition temperature of the thermoplastic resin (A),
The interface free energy between the carbon black (B) and the resin (C) is lower than the interface free energy between the carbon black (B) and the thermoplastic resin (A),
A conductive resin composition, wherein an interface free energy between carbon black (B) and resin (C) is 0 to 50 mN / m.   The conductive resin composition according to claim 1, wherein the carbon black (B) has a DBP oil absorption of 30 to 750 ml / 100 g.   The conductive resin composition according to claim 1 or 2, wherein the resin (C) is a thermoplastic elastomer or polyethylene.   A conductive masterbatch comprising the conductive resin composition according to claim 1.   The electroconductive film formed using the conductive resin composition in any one of Claims 1-3, and being extended | stretched.   A step (1) of melt-kneading a resin composition containing the conductive resin composition according to any one of claims 1 to 3, a step (2) of forming a film, and a step of stretching the film (3) The manufacturing method of the electroconductive film characterized by including this.   The method for producing a conductive film according to claim 6, wherein in the step (3), the film is biaxially stretched.   In the said process (3), the draw ratio of a film is 1.5-25 times by area ratio, The manufacturing method of the conductive film of Claim 6 or 7 characterized by the above-mentioned.   The electroconductive film obtained with the manufacturing method in any one of Claims 6-8. The surface resistivity of the conductive film according to claim 5 or 9 is 1 × 10 ⁷ Ω / or less.