CN107099077B

CN107099077B - Method for preparing conductive resin composition

Info

Publication number: CN107099077B
Application number: CN201710090051.1A
Authority: CN
Inventors: 吴东勋; 金起弘; 金东焕
Original assignee: Korea Kumho Petrochemical Co Ltd
Current assignee: Kumho Petrochemical Co Ltd
Priority date: 2016-02-19
Filing date: 2017-02-20
Publication date: 2020-07-31
Anticipated expiration: 2037-02-20
Also published as: JP2017145414A; CN107099077A; JP6386114B2; KR101830957B1; KR20170098083A

Abstract

The present invention provides a method for preparing an electrically conductive resin composition, according to one aspect of the present invention, a masterbatch containing a high content of an electrically conductive filler is prepared by mixing an electrically conductive filler and a first olefin polymer resin, and the masterbatch is mixed with a second olefin polymer resin of the same or different kind as the first olefin polymer resin, thereby being capable of preventing a reduction in mechanical properties of the olefin polymer resin and imparting good electrical conductivity.

Description

Method for preparing conductive resin composition

Technical Field

The present invention relates to a method for producing an electrically conductive resin composition, and more particularly, to a method for producing an electrically conductive resin composition capable of achieving a balance between electrical conductivity and mechanical properties by alleviating a trade-off (tradeoff).

Background

The thermoplastic resin is a plastic which is softened by heating to be plastic and hardened by cooling. The thermoplastic resin has excellent processability and moldability, and thus is widely used in various articles for daily use, office automation equipment, electric and electronic products, automobile parts, and the like.

Further, attempts to use the thermoplastic resin as a high value-added material by adding special properties according to the kind and characteristics of the product produced using the above-described thermoplastic resin have been continuously made.

In particular, when a thermoplastic resin is applied to a field where friction is generated between resin products or between the resin products and other materials, damage and contamination of the products occur due to an electrification phenomenon, and thus it is necessary to impart conductivity to the thermoplastic resin.

As described above, in order to impart conductivity to the conventional thermoplastic resin, a conductive filler such as carbon nanotube, carbon black, graphite, carbon fiber, metal powder, metal-coated inorganic powder, or metal fiber is used.

However, in order to derive a significant result of imparting conductivity, it is necessary to add about 10 to 20% by weight or more of a conductive filler to the thermoplastic resin, which results in lowering the inherent mechanical properties of the thermoplastic resin, such as impact resistance, elongation, and abrasion resistance.

In particular, in the field where both the electrical conductivity and mechanical properties of thermoplastic resins are required, for example, in the field such as automobile fuel tanks or fuel hoses, the commercialization of products is limited due to the problem of maintaining a balance between the two.

Further, when it is necessary to impart conductivity to a high-viscosity thermoplastic resin, there is a problem that sufficient conductivity by the addition of the conductive filler cannot be achieved due to the characteristics of the thermoplastic resin.

Disclosure of Invention

The present invention aims to provide a conductive resin composition which prevents a reduction in mechanical properties of a thermoplastic resin, particularly, a reduction in mechanical properties of a high-viscosity thermoplastic resin, and can realize good conductivity.

An aspect of the present invention provides a method for preparing a conductive resin composition, the method comprising: a step (a) of preparing a master batch by extruding carbon nanotubes and a first olefin polymer resin; and a step (b) of mixing the master batch and a second olefin polymer resin.

In one embodiment, the step (a) may be performed at a temperature of 180 to 300 ℃.

In one embodiment, the extrusion may be performed at a rate of 10 to 500 kg/hr in the step (a).

In one embodiment, the carbon nanotubes may be included in the masterbatch in an amount of 10 to 30 wt%.

In one embodiment, the conductive resin composition may include 0.1 to 10% by weight of carbon nanotubes.

In one embodiment, the apparent density of the carbon nanotubes may be 0.01 to 0.2 g/ml.

In one embodiment, the first olefin polymer resin and the second olefin polymer resin may each be one selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, polyethylene copolymer, polypropylene, and a mixture of two or more thereof.

In one embodiment, the polyethylene copolymer may be one selected from the group consisting of ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and a mixture of two or more thereof.

In one embodiment, the first olefin polymer resin may be prepared by mixing polyethylene and ethylene vinyl acetate at a weight ratio of 2 to 3: 1.

In one embodiment, before the step (b), a step of pelletizing the product of the step (a) may be further included.

Another aspect of the present invention provides a method for manufacturing an automobile fuel tank, which further comprises, after the step (b): and (c) molding the conductive resin composition.

In another aspect of the present invention, there is provided a method for preparing a fuel hose for an automobile, the method further comprising, after the step (b): and (c) molding the conductive resin composition.

According to an aspect of the present invention, a masterbatch containing a high content of an electrically conductive filler is prepared by mixing an electrically conductive filler and a first olefin polymer resin, and the masterbatch is mixed with a second olefin polymer resin of the same or different kind as the first olefin polymer resin, whereby it is possible to prevent a reduction in mechanical properties of the olefin polymer resin and impart good electrical conductivity.

The effects of the present invention are not limited to the above-described effects, and it should be understood that the effects include all the effects inferred from the detailed description of the present invention or the structures of the present invention described in the claims.

Drawings

Fig. 1 schematically illustrates a method of preparing a conductive resin composition according to an aspect of the present invention.

Fig. 2 is a graph showing surface resistance values of molded articles prepared using the resin compositions according to examples and comparative examples of the present invention.

Fig. 3 is a graph showing impact strength values of molded articles prepared using the resin compositions according to examples and comparative examples of the present invention.

Fig. 4 is a graph showing tensile strength values of molded articles prepared using the resin compositions according to examples and comparative examples of the present invention.

Fig. 5 is a graph showing elongation values of molded articles prepared using the resin compositions according to examples and comparative examples of the present invention.

Detailed Description

The present invention will be described below with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Throughout this document, the terms "comprising or including" and/or "having" mean one or more other components, steps, operations, and/or not excluding the presence or addition of elements thereof in addition to the described components, steps, operations, and/or elements.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 schematically illustrates a method of preparing a conductive resin composition according to an aspect of the present invention. Referring to fig. 1, a method of preparing a conductive resin composition according to an aspect of the present invention may include: a step (a) of preparing a master batch by extruding carbon nanotubes and a first olefin polymer resin; and a step (b) of mixing the master batch and a second olefin polymer resin.

The conductive resin composition may be basically composed of a polymer resin having mechanical properties and moldability at a certain level and a conductive material, for example, a metal and other inorganic substances, etc., which can impart conductivity to the polymer resin. In order to prepare the above conductive resin composition, a process for mixing a polymer resin and a conductive material is required.

In order to improve the conductivity of the conventional conductive resin composition, a technique of increasing the content of the conductive material is proposed. However, if the content of the same type of conductive material is increased to a certain level or more, and particularly if the content of the carbon nanotubes is increased to a certain level or more, there is a problem that not only the mechanical properties of the resin itself are reduced, but also the processability, workability, and the like are reduced. To solve these problems, attempts have been made to increase the total content of the conductive material in the conductive resin composition by using carbon black or the like in combination, which has little effect of imparting conductivity as compared with carbon nanotubes but has good processability and workability.

However, the above method merely adjusts the kinds and contents of the conductive materials differently, but has a common point that the mixing of the resin and the conductive materials is achieved through a single process.

In this regard, in the step (a), a high-concentration carbon nanotube master batch may be prepared by mixing and extruding carbon nanotubes as the conductive filler and the first olefin polymer resin.

As used herein, the term "master batch" refers to a material in which a high concentration of additives is previously dispersed when a resin composition is prepared. The dispersibility of the carbon nanotubes in the olefin polymer resin can be improved by preparing the above-mentioned master batch, so that uniform conductivity can be imparted to the entire region of the conductive resin composition.

At this time, the master batch may be made in a spherical shape (sphere), a pellet shape (pellet), etc., but there is no limitation in its shape as long as the dispersibility of the carbon nanotubes can be improved by mixing with a thermoplastic resin in a subsequent step.

The carbon nanotube is a material for imparting conductivity to a thermoplastic polymer resin, which is a nonconductor, and particularly, a material for imparting conductivity to an olefin polymer resin, and reduces the surface resistance of a plastic substrate prepared by molding a resin composition to which the carbon nanotube is added, thereby being capable of improving conductivity.

Examples of the method for synthesizing the carbon nanotube include arc discharge method, pyrolysis method, laser deposition method, plasma chemical vapor deposition method, thermal chemical vapor deposition method, etc., but the synthesis method is not limited and all the produced carbon nanotubes can be used.

The carbon nanotube may be one selected from the group consisting of a single-walled carbon nanotube, a double-walled carbon nanotube, a multi-walled carbon nanotube, a hollow tubular carbon nanofiber (cup-stackedcarbon nanofiber) in which a plurality of truncated conical graphenes are stacked, and a mixture of two or more of them, and may be preferably a multi-walled carbon nanotube which is easy to manufacture and economical, but is not limited thereto.

On the other hand, an olefin polymer resin, which is a parent material of the master batch, has small changes in physical properties in a thermoplastic resin over a relatively wide temperature range, and is excellent in moldability, weather resistance, chemical resistance, and the like.

The first olefin polymer resin may be one selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, polyethylene copolymer, polypropylene, and a mixture of two or more thereof, preferably, may be a polyethylene series, and more preferably, may be high density polyethylene, but is not limited thereto.

Also, the polyethylene copolymer may be one selected from the group consisting of ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and a mixture of two or more thereof, but is not limited thereto.

That is, the first olefin polymer resin may be a single polymer polymerized from the same monomer, a copolymer polymerized from different monomers, or a mixture thereof. The polymerization form of the copolymer is not limited, and the copolymer may be an alternating copolymer, a random copolymer, a block copolymer, or a graft copolymer.

In particular, when the master batch is prepared, the balance of the electrical conductivity and the mechanical properties of the resin composition is better maintained by the interaction between different kinds of olefin polymer resin mixtures in the case of using them than in the case of using the same kind of olefin polymer resin.

Specifically, the first olefin polymer resin may be obtained by mixing Polyethylene (PE) and Ethylene Vinyl Acetate (EVA) at a weight ratio of 1 to 5:1, preferably 2 to 3: 1. If the weight ratio between the two is outside the above range, the effect of improving mechanical properties is slight as compared with the case of using the same kind of resin.

On the other hand, the step (a) may be performed at a temperature of 180 to 300 ℃, preferably 220 to 240 ℃, more preferably 230 ℃. If the process temperature of the step (a) is less than 180 ℃, the olefin polymer resin is partially melted, thereby reducing the extrusion moldability and the dispersibility of the carbon nanotubes, and if the process temperature is more than 300 ℃, thermal decomposition or denaturation of the olefin polymer resin occurs.

And, in the step (a), the carbon nanotubes and the first olefin polymer resin may be extruded at 10 to 500 kg/hr, preferably, 10 to 30 kg/hr. If the extrusion rate is less than 10 kg/hr, productivity may be reduced, and if the extrusion rate is more than 500 kg/hr, mixing uniformity of the carbon nanotubes and the first olefin polymer resin may be reduced.

The masterbatch that is the product of step (a) may include a high content of carbon nanotubes. For example, the content of the carbon nanotubes included in the masterbatch may be 10 to 30 wt%.

If the content of the carbon nanotubes included in the masterbatch is less than 10 wt%, the carbon nanotubes are concentrated on the masterbatch to a slight extent, and if the content is more than 30 wt%, the composition of the prepared masterbatch is not uniform, and thus the processability is lowered.

The carbon nanotubes used when preparing the master batch are processed into a pellet shape by mechanically and physically tableting a powdery material, and the apparent density of the carbon nanotubes after processing may be 0.01 to 0.2g/ml, preferably, 0.05 to 0.2 g/ml. If the apparent density of the carbon nanotubes is outside the range, it is difficult to prepare a concentrated master batch containing 10% by weight or more of carbon nanotubes. Also, the carbon nanotubes processed into the pellet shape prevent powder from scattering during operation, so that the operation environment can be improved.

On the other hand, the extruder used in the extrusion in the step (a) may be a single screw extruder having one screw or a multi-screw extruder having a plurality of screws, and preferably, for uniform mixing and extrusion between the components, an example thereof may be a twin screw extruder having two screws.

In this case, in the kneading process using the extruder, in order to suppress breakage of the carbon nanotubes, it is preferable to adopt a method of using a twin-screw extruder to feed the olefin polymer resin from the extruder side and using a side feeder (Sidefeeder) to feed the carbon nanotubes to the extruder for melt kneading.

In the step (b), dilution (let-down) is performed by mixing a high content of the carbon nanotubes included in the masterbatch with a second olefin polymer resin. The amount of the second olefin polymer resin charged in the step (b) may be any amount as long as the content of carbon nanotubes in the conductive resin composition as a product is diluted to 0.1 to 10% by weight.

The second olefin polymer resin may be the same kind as the first olefin polymer resin, and may be a different kind as needed. However, in the case where the kinds of the first olefin polymer resin and the second olefin polymer resin are different, also in view of compatibility therebetween, olefin polymer resins in which one or more kinds of monomers respectively contained therein are the same or one or more kinds of resins respectively contained therein are the same may be used.

For example, when the first olefin polymer resin is a mixture of polyethylene and ethylene vinyl acetate, the second olefin polymer resin may be polyethylene, a polyethylene copolymer, or a mixture thereof.

The conductive resin composition prepared by the step (a) and the step (b) uses a high viscosity olefin polymer resin as a parent material, and improves conductivity and maintains mechanical properties compared to a conductive resin composition according to an existing preparation method, for example, compared to a conductive resin composition prepared without a masterbatch, thereby enabling to achieve both in balance.

Specifically, the dilution may be performed by mixing the masterbatch and the second olefin polymer resin so that the content of the carbon nanotubes included in the conductive resin composition is 0.1 to 10% by weight.

If the content of the carbon nanotubes included in the conductive resin composition is less than 0.1 wt%, the conductivity may be reduced, and if the content is more than 10 wt%, the mechanical properties may be significantly reduced.

In the step (b), the master batch and the second olefin polymer resin may be mixed by a melt kneading method, an in-situ polymerization method, a solution mixing method, or the like, and preferably, a melt kneading method may be used, which can uniformly disperse the carbon nanotubes into the resin at high temperature and high shear by using an extruder or the like, so that a large capacity and a manufacturing cost saving can be achieved. The types, characteristics, selection criteria, and the like of the extruder are the same as those described above.

In the step (a) or the step (b), at least one additive selected from the group consisting of a flame retardant, an impact modifier, a flame retardant aid, a lubricant, a plasticizer, a heat stabilizer, an anti-dropping agent, an antioxidant, a compatibilizer, a light stabilizer, a pigment, a dye, an inorganic additive, and an anti-dropping agent may be further added according to the purpose of use of the conductive resin composition.

The content of the additive may be 0.1 to 10% by weight based on the total weight of the conductive resin composition. If the content of the additive is less than 0.1% by weight, the effect suitable for the purpose of use cannot be obtained, and if the content of the additive is more than 10% by weight, the physical properties inherent to the olefin polymer resin are lowered.

The conductive resin composition can be made into plastic molded articles by injection molding, extrusion molding, etc., and can be used for various articles for daily use, office automation equipment, electric and electronic products, automobile parts, etc. by using a widely applicable polyethylene resin as a base material.

In particular, the conductive resin composition can be applied to automobile parts that require mechanical properties at a certain level or more and conductivity at a certain level or more in balance, and in particular, can be applied to automobile fuel tanks (fuel tank) or automobile fuel hoses (fuel hose). The chemical, electrochemical and mechanical properties required for the above-mentioned molded article can be satisfied by the steps (a) and (b), and thus, the conductive resin composition can be molded by a mold to obtain a final product.

And, a plastic molded article prepared using the conductive resin composition can be made to have 10 by differently adjusting the content of the carbon nanotube according to the application field²～10¹⁰The surface resistance range of Ω/sq can be made to 10, particularly, in the field where antistatic and good conductivity imparting ability are required²～10⁸Surface resistance range of Ω/sq.

Example 1

Multi-walled carbon nanotubes (MWCNTs) were fed into a side feeder of a twin-screw extruder, polyethylene (HDPE, melt index of 5.0g/10min, astm d1238) was fed into a main hopper at an input rate of 25 kg/hr, and melt-kneaded under a kneading rate of 200rpm and a processing temperature of 230 ℃, thereby preparing a masterbatch having a carbon nanotube content of 10 wt%.

The prepared master batch and various kinds of polyethylene (HDPE, melt index of 0.3g/10min, ASTM D1238) were simultaneously fed into a twin-screw extruder, and melt-kneaded under the conditions of a kneading speed of 200rpm and a processing temperature of 250 ℃ to prepare a resin composition having a carbon nanotube content of 6 wt%.

Example 2

A resin composition was obtained in the same manner as in example 1, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 5% by weight.

Example 3

A resin composition was obtained in the same manner as in example 1, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 4% by weight.

Example 4

A resin composition was obtained in the same manner as in example 1, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 3% by weight.

Example 5

Multi-walled carbon nanotubes (MWCNTs) were fed into a side feeder of a twin-screw extruder, and a resin obtained by mixing polyethylene (HDPE, melt index of 5.0g/10min, ASTM D1238) and Ethylene Vinyl Acetate (EVA) at a weight ratio of 7:3 was fed into a main hopper at an input rate of 25 kg/hr, followed by melt-kneading at a kneading rate of 200rpm and a processing temperature of 230 ℃, thereby preparing a master batch having a carbon nanotube content of 10 wt%.

Then, a resin composition having a carbon nanotube content of 6 wt% was prepared in the same manner as in example 1.

Example 6

A resin composition was obtained in the same manner as in example 5, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 5% by weight.

Example 7

A resin composition was obtained in the same manner as in example 5, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 4% by weight.

Example 8

A resin composition was obtained in the same manner as in example 5, except that the content of the carbon nanotubes contained in the master batch was adjusted to 10% by weight, and the content of the carbon nanotubes contained in the resin composition was adjusted to 3% by weight.

Comparative example 1

Multi-walled carbon nanotubes (MWCNTs) were fed into a side feeder of a twin-screw extruder, polyethylene (HDPE, melt index of 0.3g/10min, ASTM D1238) was fed into the twin-screw extruder at an input rate of 25 kg/hr, and then melt-kneaded under a kneading rate of 200rpm and a processing temperature of 250 ℃, thereby preparing a masterbatch having a carbon nanotube content of 6 wt%.

Comparative example 2

A resin composition was obtained in the same manner as in comparative example 1, except that the content of the carbon nanotubes contained in the resin composition was adjusted to 5 wt%.

Comparative example 3

A resin composition was obtained in the same manner as in comparative example 1, except that the content of the carbon nanotubes contained in the resin composition was adjusted to 4 wt%.

Comparative example 4

A resin composition was obtained in the same manner as in comparative example 1, except that the content of the carbon nanotubes contained in the resin composition was adjusted to 3 wt%.

Experimental example 1 measurement of conductivity according to preparation method and content of carbon nanotube

The resin compositions according to examples 1 to 8 and comparative examples 1 to 4 were injection-molded at 210 ℃ using a hydraulic injection molding machine, thereby producing injection-molded products having a rectangular shape with a width of 30cm and a length of 20 cm.

The surface resistance (Ω/sq) of each of the prepared injection-molded products was measured by a surface resistance tester (SIMCO, ST-4), and the results are shown in FIG. 2.

Referring to fig. 2, it was confirmed that the carbon nanotube-polymer nanocomposite prepared by diluting the content of the carbon nanotube after the masterbatch preparation step had the same (examples 4, 8 and 4) or reduced (examples 1 to 3, 5 to 7 and 1 to 3) surface as or less than the carbon nanotube-polymer nanocomposite prepared without the masterbatch preparation stepResistance, in particular, having a minimum of 10⁵Surface resistance values of the order of Ω/sq (examples 1 and 5).

In particular, referring to the interval in which the content of the carbon nanotubes was increased from 4 wt% to 5 wt%, it was observed that the surface resistance was drastically reduced in the case where the content of the carbon nanotubes was diluted after the masterbatch preparation step (examples 2 to 3 and examples 6 to 7) as compared with the case where the masterbatch preparation step was not performed (comparative example 2 and comparative example 3), and it was confirmed that the effect of significantly improving the content of the carbon nanotubes was obtained only by adjusting the content of the carbon nanotubes to a small extent.

In addition, when a master batch was prepared, in the case of using a mixture of polyethylene and ethylene vinyl acetate as a thermoplastic resin (example 7), it was seen that the conductive resin composition including a content of carbon nanotubes had a more reduced surface resistance than the case of using polyethylene alone as a thermoplastic resin (example 3).

As can be seen from the above results, even if carbon nanotubes as the conductive filler are included in the same content, when the conductive resin composition is prepared, good conductivity can be imparted by preparing a master batch and diluting it, and further conductivity can be improved by using a mixture of different kinds of thermoplastic resins when preparing the master batch.

Comparative example 5

Polyethylene without carbon nanotubes (HDPE, melt index 0.3g/10min, ASTM D1238) was used as the resin composition.

Experimental example 2 measurement of mechanical Properties according to preparation method and content of carbon nanotube

The resin compositions according to examples 1 to 8 and comparative examples 1 to 5 were injection-molded at 250 ℃ using an injection-molding machine to prepare samples for measuring mechanical properties, and the Izod impact strength, tensile strength and elongation of each sample were measured according to the following methods, and the results are shown in FIGS. 3 to 5.

Measuring the 1/8' thick sample according to ASTM D256.

Tensile Strength (kgf/cm)²) And an elongation (%), measured under the condition of 20 mm/min according to ASTM D638.

Referring to FIG. 3, it can be seen that the impact strength of the thermoplastic resin compositions (examples 1 to 8 and comparative examples 1 to 4) prepared by adding carbon nanotubes is reduced as compared to the thermoplastic resin without adding carbon nanotubes (comparative example 5).

However, the resin compositions prepared by diluting the masterbatch after its preparation (examples 1 to 8) had lower impact strength reductions than the resin compositions prepared without the masterbatch preparation step (comparative examples 1 to 4).

In particular, it was confirmed that in the case where the carbon nanotube content was 5 wt%, the impact strength was about 2 times higher in the resin composition (example 6) prepared so that the master batch contained different kinds of thermoplastic resins, as compared with the case where the resin composition containing a single thermoplastic resin was prepared (example 2) or the case where the resin composition was not subjected to the master batch preparation step (comparative example 2).

Referring to fig. 4, it was confirmed that tensile strength of the resin compositions was improved as the amount of the added carbon nanotubes was increased as compared to the thermoplastic resin (comparative example 5) to which carbon nanotubes were not added as the conductive filler (examples 1 to 8 and comparative examples 1 to 4), and in particular, tensile strength of the resin compositions prepared through the masterbatch preparation step including a single thermoplastic resin (examples 1 to 4) and the resin compositions prepared without the masterbatch preparation step (comparative examples 1 to 4) showed similar increasing trends as the amount of the carbon nanotubes was increased.

Referring to fig. 5, in the case of the resin compositions (examples 1 to 8) prepared through the masterbatch production step, the elongation inherent to the thermoplastic resin (comparative example 5) was maintained even though the content of the carbon nanotubes was increased, whereas in the case of the resin compositions (comparative examples 1 to 4) prepared without the masterbatch production step, the elongation was significantly reduced.

As can be seen from the above results, even though the same content of the conductive filler is contained, a difference in mechanical properties slightly occurs depending on whether or not a masterbatch preparation step is passed, and in particular, a resin composition prepared by diluting the content of the carbon nanotubes after preparing the masterbatch exhibits more excellent mechanical properties.

The above description of the present invention is merely exemplary, and it will be understood by those skilled in the art that the present invention may be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Accordingly, the above-described embodiments are merely illustrative in all respects, and not restrictive. For example, the components described as a single type may be dispersed and implemented, and similarly, the components described using the dispersion may be implemented in a combined form.

The scope of the present invention is indicated by the appended claims rather than by the foregoing detailed description, and all changes and modifications that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. A method for producing a conductive resin composition, comprising:

a step (a) of preparing a master batch by extruding carbon nanotubes and a first olefin polymer resin; and

a step (b) of mixing the master batch and a second olefin polymer resin,

the first olefin polymer resin and the second olefin polymer resin are different in kind,

the content of the carbon nanotubes in the master batch is 10 to 30 weight percent,

the content of the carbon nanotubes in the conductive resin composition is 0.1 to 10% by weight,

the apparent density of the carbon nano tube is 0.01 g/ml-0.2 g/ml,

the first olefin polymer resin is obtained by mixing polyethylene and ethylene vinyl acetate at a weight ratio of 1-5: 1.

2. The method for preparing an electrically conductive resin composition according to claim 1, wherein the step (a) is carried out at a temperature of 180 ℃ to 300 ℃.

3. The method of producing the electrically conductive resin composition according to claim 2, wherein the extrusion is performed at a rate of from 10 to 500 kg/hr in step (a).

4. The method for preparing an electroconductive resin composition according to claim 1, wherein the second olefin polymer resin is one selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene copolymer, polypropylene and a mixture of two or more thereof.

5. The method for preparing the conductive resin composition according to claim 4, wherein the ethylene copolymer is one selected from the group consisting of ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and a mixture of two or more thereof.

6. The method of preparing a conductive resin composition according to claim 1, further comprising a step of pelletizing the product of the step (a) before the step (b).

7. A method for producing an automobile fuel tank, comprising the step of producing an electrically conductive resin composition by the method for producing an electrically conductive resin composition according to claim 1,

after the step (b), further comprising: and (c) molding the conductive resin composition.

8. A method for producing an automotive fuel hose, comprising the step of producing an electroconductive resin composition by the method for producing an electroconductive resin composition according to claim 1,