KR100614608B1 - Conductive polymer composition containing ozone-treated carbon nanotube and ptc device prepared therefrom - Google Patents

Abstract

The present invention relates to a conductive polymer composition for PTC devices comprising a polyolefin resin and a conductive filler, wherein the conductive polymer composition for a PTC (positive temperature coefficient) device containing ozonated carbon nanotubes as a conductive filler and a PTC prepared using the same It relates to an element.

The conductive polymer composition for the PTC device of the present invention is economical because it exhibits excellent PTC strength with a small amount of conductive filler, and the PTC device manufactured using the conductive polymer composition for the PTC device has a low specific resistance, a high maximum specific resistance, and It exhibits excellent PTC strength and eliminates the negative temperature coefficient (NTC) phenomenon that occurs after overcurrent blocking, and is useful as a device such as a constant temperature wire, an overcurrent blocking device, a circuit protection device, and a heater.

Polyolefin, High Density Polyethylene, Ozone Treatment, Carbon Nanotube, PTC Element

Description

CONDUCTIVE POLYMER COMPOSITION CONTAINING OZONE-TREATED CARBON NANOTUBE AND PTC DEVICE PREPARED THEREFROM}             

1 is a schematic diagram of an ozone treatment apparatus;

2 is an embodiment of a PTC device made using the conductive polymer composition of the present invention,

3 is FT-IR results for the ozonated carbon nanotubes of the present invention,

4 is a temperature-resistance curve of the amount of carbon nanotubes used in a PTC device manufactured using the ozonated carbon nanotubes of the present invention,

5 is a temperature-resistance curve at ozone treatment time of carbon nanotubes in a PTC device manufactured using ozonated carbon nanotubes of the present invention.

The present invention relates to a conductive polymer composition for PTC devices containing ozonated carbon nanotubes and to a PTC device manufactured using the same. More specifically, in a conductive polymer composition for PTC devices comprising a polyolefin resin and a conductive filler, The present invention relates to a conductive polymer composition for a PTC device containing ozonated carbon nanotubes as a conductive filler, and to a PTC device having excellent PTC properties and NTC phenomena which may occur after overcurrent blocking.

Polymer materials have been used as electrical insulators due to their low electrical conductivity, but the addition of electrically conductive fillers to such polymer matrices has led to the rise in demand and necessity as polymer materials with electrical conductivity emerge.

In general, polymer materials to which an electrically conductive filler is added show excellent electrical conductivity at room temperature, but cause a sharp increase in electrical resistance at the melting temperature of the polymer resin. This phenomenon is called the positive temperature coefficient (PTC) effect, and the cause of the PTC phenomenon can be explained by the change of the crystalline state and the amorphous state in the polymer. That is, when the temperature rises and becomes near the melting point of the resin, the gap between the conductive filler particles and the gap between the aggregates increases, thereby destroying the conductive network formed therein, thereby preventing the tunneling phenomenon of electrons.

The PTC device using such a rapid increase in electrical resistance is conductive because of its low resistance at room temperature, but it is a so-called 'polymer fuse' that blocks overcurrent due to the rapid increase in electrical resistance in a relatively narrow temperature range as the temperature increases. Play a role. These PTC devices have recently been used for the purpose of protecting circuits from overcurrent in the field of electronic products requiring high density and high sensitivity. Preferred PTC devices should have a low resistivity ρ _RT and a high maximum resistivity ρ _max at room temperature, from which high PTC strengths must be satisfied.

As a method of obtaining a PTC device having a low specific resistance at room temperature, a conductive polymer composition obtained using carbon black and high density polyethylene [ J. Appl. Polym. Sci. , H. Tang et al., 1993, 48 , 1795] or a composition in which carbon black was silane-treated and melt mixed with high-density polyethylene, a polymer resin [ Polymer (Korea), TJ Moon et al., 1995, 19, 789]. A method of manufacturing a PTC device from the known is known. In addition, the PTC device is a PTC composition in which an organic polymer in which 1 to 3 parts by weight of silane is grafted to 100 parts by weight of polyolefin and 30 to 85 parts by weight of conductive particles are mixed with respect to 100 parts by weight of the organic polymer [Korea Patent Application No. 2000- 16491 or (a) a semicrystalline polymer component comprising nylon-11; (b) an electrically conductive polymer comprising a carbonaceous particulate conductive filler, said composition having a resistivity of 100 Ωcm or less at 25 ° C. and a resistivity of at least 10 ³ times the resistivity at 25 ° C. at a temperature TS of 150 ° C. or higher. It is reported that it can be manufactured from a composition [Korean Patent Application No. 1999-9982].

Korean Patent Laid-Open Publication No. 2004-0016675 discloses a PTC device by laminating an electrode and an electrolyte metal foil on a thin film of a resistor made of a conductive polymer resin composition comprising a crystalline polyolefin resin and a conductive filler powder. Known methods of preparation are known. In addition, Korean Patent Laid-Open Publication No. 2004-0016677 discloses stacking an electrode and an electrolyte metal foil on a thin film of a resistor made of a conductive polymer composition obtained by directly treating a conductive filler surface with a silane coupling agent and then melt-mixing it with a crystalline polyolefin resin. The manufacturing method of a PTC element including the thing was disclosed.

In summary, a commonly used method for manufacturing a PTC device having excellent PTC strength has been tried in various ways depending on the type of conductive filler, the amount of its addition, and the processing method when the conductive polymer composition is prepared.

However, increasing the amount of conductive filler added may reduce the resistivity of the conductive polymer composition but causes a change in PTC strength and NTC phenomenon. The NTC phenomenon causes the PTC device to return to low resistance when it returns to room temperature low current and low temperature after overcurrent blocking, but on the contrary, when the melting point lasts longer or rises to a higher temperature, the conductive filler particles are free to flow. Re-aggregation occurs to form a new conductive network by rearranging, thereby reducing the resistance of the resin. This NTC phenomenon is fatal in a circuit protection device that cuts off the overcurrent by continuously maintaining a high resistance while the overcurrent is applied.

Therefore, after setting the preferred amount of the conductive filler exhibiting the maximum PTC strength at room temperature, a method of surface treatment has been proposed. In another preferred method, a high crosslinked structure such as high density polyethylene is used to remove NTC phenomenon. It is proposed to use a polymer resin having.

The conductive filler is preferably a metal powder selected from carbon nanotubes, carbon black, carbon fiber, and the like, or nickel powder, gold powder, copper powder, or metal alloy powder. Among them, carbon nanotubes are attracting attention as next-generation materials because of their excellent electrical, chemical, mechanical and structural properties because carbon atoms have a strong covalent bond with a hexagonal honeycomb cylindrical structure.

Accordingly, the present inventors have tried to develop an improved PTC device having excellent PTC properties and NTC phenomena. As a result, the present inventors have prepared a conductive polymer composition for PTC devices containing ozone on a surface of carbon nanotubes as a conductive filler and using the same. The present invention was completed by fabricating a PTC device and confirming an increase in PTC strength due to an increase in oxygen-containing functional groups on the surface of the carbon nanotubes.

It is an object of the present invention to provide a conductive polymer composition for PTC devices wherein the conductive filler comprises ozonated carbon nanotubes.

Another object of the present invention is to provide a method for producing a conductive polymer composition for PTC devices comprising the ozone treated carbon nanotubes.

Still another object of the present invention is to provide a PTC device manufactured using the conductive polymer composition for the PTC device.

The present invention provides a conductive polymer composition for a PTC (positive temperature coefficient) device, wherein the conductive filler is a ozone-treated carbon nanotube in a conductive polymer composition comprising a polyolefin resin and a conductive filler.

The conductive polymer composition for the PTC device includes 1 to 5 parts by weight of ozonated carbon nanotubes based on 100 parts by weight of the polyolefin resin. In addition, the carbon nanotubes have a particle size diameter of 10 to 50 nm.

The conductive polymer composition comprises a specific resistance (ρ _RT) value of 10 ohm and ³ and ^2-10 cm, is the PTC intensity change from room temperature to the melting point (Tm) + 5 ℃ range of the polyolefin-based polymer 10 ^{4-10 5} at room temperature .

The present invention is fixed to the surface of the carbon nanotubes at room temperature ozone generation amount of 1 to 12 g / h, ozone concentration of 1 to 60 mg / l, and after the ozone treatment for 0.1 to 8 hours to produce carbon nanotubes, polyolefin resin It provides a method for producing the conductive polymer composition for the PTC device prepared by melting and mixing 1 to 5 parts by weight of the ozonated carbon nanotubes with respect to 100 parts by weight.

In addition, the present invention is prepared by compression molding an electrolytic metal foil having a thickness of 10 to 50 ㎛, more preferably 30 to 50 ㎛ on both surfaces of the conductive polymer composition for PTC devices, and bonding a pair of electrodes using a conductive adhesive. Provides a PTC device.

The PTC element is in the form of a circular sheet having a thickness of 0.5 to 1 mm, has a specific resistance of 10 ² ohm · cm or less at room temperature, a maximum specific resistance of 10 ⁶ to 10 ⁸ ohm · cm, and a PTC strength change of 10 ² to 10 ^3.5 . .

Hereinafter, the present invention will be described in detail.

The present invention provides a conductive polymer composition for a PTC device comprising a polyolefin resin and a conductive filler, wherein the conductive filler is an ozonated carbon nanotube.

More specifically, the conductive polymer composition for PTC device of the present invention comprises 1 to 5 parts by weight of ozonated carbon nanotubes based on 100 parts by weight of polyolefin resin.

The polyolefin resin used in the present invention should be able to improve the filling property of the conductive particles while having crystallinity. Preferred examples thereof include one or more selected from the group consisting of polyethylene, polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer and ethylene ethyl acrylate copolymer. Can be used. More preferably, in the case of the polyethylene derivative, it is possible to increase the resistance of the composition due to the increase in temperature in a relatively narrow temperature range, thereby exhibiting excellent PTC properties. That is, the polyethylene derivative can prevent loss of physical properties by heat due to the low melting point. In particular, in the present invention, the most preferable PTC strength can be obtained when using high-density polyethylene (HDPE) having the advantages of high crystallinity, ductility and compatibility among the polyethylene derivatives.

Preferred conductive fillers may be any one selected from the group consisting of carbon nanotubes, graphite powders, carbon blacks and carbon fibers or metal powders selected from nickel powders, gold powders, copper powders and alloy powders of the above metals. Is using carbon nanotubes, and the carbon nanotubes have a particle size diameter of 10 to 50 nm. In the above, when the particle size diameter of the carbon nanotube is less than 10 nm, the phenomenon occurs that the carbon nanotubes are not dispersed and agglomeration occurs, and when the diameter exceeds 50 nm, the length of the particles of the carbon nanotube is long, so that rearrangement is difficult to occur. It is not preferable because the phenomenon of decreasing resistance does not appear.

In this case, the ozone treated carbon nanotubes are preferably used in an amount of 1 to 5 parts by weight of the ozone treated carbon nanotubes based on 100 parts by weight of the polyolefin resin. At this time, if less than 1 part by weight, there is a problem that the conductive network is difficult to form because of the small amount of carbon nanotubes in the resin, and when used in excess of 5 parts by weight, the gap between the conductive filler particles becomes narrow, which makes it difficult to destroy the conductive network. It is not desirable.

In the melt mixing of the conductive polymer composition, the preferred temperature is carried out at a temperature of 20 ℃ or more than the melting temperature (Tm) of the polyolefin resin used. At this time, when mixing at a temperature lower than the melting temperature (Tm) of the polyolefin-based resin, the mixing between the polyolefin-based resin and the conductive filler is not completely achieved, while if the temperature is too high, by the thermal decomposition of the used polyolefin-based resin, There are disadvantages in that physical properties such as physical property change and structural change change.

In melt mixing of the conductive polymer composition, the preferred rate of temperature increase is 5 ° C / min. At this time, when the temperature increase rate is less than 5 ℃ / min, the productivity is lowered, if it exceeds 5 ℃ / min, due to the difference in the thermal expansion coefficient between the polyolefin resin and the conductive filler causes a change in electrical properties.

In the melt mixing of the conductive polymer composition, the preferred mixing time is to mix and cool within a short time after reaching the preferred melting temperature in order to produce a conductive polymer composition having a relatively low crystallinity, more specifically 20 Minutes are preferred, but more than 20 minutes is uneconomical because there is no effect on physical properties.

In the conductive polymer composition for PTC devices of the present invention, the ozonated carbon nanotubes are characterized by the relationship between the amount of ozone generated, ozone concentration and ozone treatment time. Thus, the ozone treated carbon nanotubes are fixed at an ozone generation amount of 1 to 12 g / h and an ozone concentration of 1 to 60 mg / l at room temperature, and the ozone treatment time is performed for 0.1 to 8 hours. Preferred when prepared by direct ozonation.

As a more preferred embodiment ozonated carbon nanotubes are prepared by fixing ozone generation amount 8 g / h, ozone concentration 23 mg / l, ozone treatment time 2 to 8 hours.

At this time, when the amount of ozone generated, ozone concentration and ozone treatment time is low in the above-mentioned preferred range, the effect of ozone does not appear and surface modification is not performed, and when the amount of ozone generated, ozone concentration and ozone treatment time is high. In addition, due to the limited functionality of carbon nanotubes reacting with ozone due to the saturation of ozone, there is almost no difference in the effects of surface modification by ozone treatment. In particular, when the ozone concentration is high, Korean Patent Application No. 2004-16035 reported that the decomposition of the crystalline polyolefin resin was performed under an ozone concentration of 50 to 1000 ppm with respect to 1 g of the polymer, which is not preferable.

1 is a schematic view of an ozone treatment apparatus, in which an oxygen generator (a), a pressure gauge (b), an ozone generator (c), a valve (d), a reactor (e), a KI solution tank (f) and a hood ( g). In the ozone treatment apparatus, the reactor (e) is preferably a material such as glass, quartz, plastic, etc., not a metal material which is easily oxidized to ozone. In addition, the pipe connecting the respective components of the ozone treatment device is preferably a Teflon material that is easy to handle and corrosion-resistant to ozone.

In the conductive polymer composition for a PTC device comprising a polyolefin resin and a conductive filler, the present invention is directly ozonated to the surface of the carbon nanotubes, the conductive filler, and then mixed with a polyolefin resin to prepare a conductive polymer composition, It is possible to avoid process temperature setting constraints that may occur in the process.

FIG. 2 shows a preferred embodiment of a PTC device manufactured using the conductive polymer composition for the PTC device. The conductive polymer composition 1 is preformed into a circular sheet and has a thickness of 10 to 50 on both sides of the circular sheet. The PTC element manufactured by compression-molding the electrolyte metal foil 2 of 30 micrometers, More preferably, 30-50 micrometers and bonding a pair of electrode 3 using a conductive adhesive is provided.

Irrespective of the size, the PTC element is preferably in the form of a circular sheet having a thickness of 0.5 to 1 mm, and the electrolytic metal foil uses an electrolytic copper or aluminum metal foil having low resistance. When the electrolyte metal foil is laminated in the above, the thickness may be controlled by compression molding using a hot press in the melting temperature range of the crystalline polyolefin resin used without using an adhesive.

Two electrodes may be bonded to both surfaces of the prepared thin film specimen using a low-resistance conductive adhesive, and the two electrodes used may be selected from iron, copper, or aluminum.

The PTC element has a specific resistance of 10 ² ohm · cm or less at room temperature, a maximum specific resistance of 10 ⁶ to 10 ⁸ ohm · cm, and a PTC strength change of 10 ² to 10 ^3.5 .

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

1. Preparation of Conductive Polymer

<Example 1>

With respect to the conditions in the ozone generator 3, the amount of ozone generation 8 g / h and the ozone concentration 23 mg / l are set, and carbon nanotubes (purity; 40 to 99%, length; 10 to 50 µm, diameter; 10 to 10) 20 nm of ILJIN Nanotech Co., Ltd. was added thereto, followed by direct ozone treatment for 2 hours. Then, with respect to 100 parts by weight of pure high density polyethylene (Honam Chem Co., Tm: 135 ℃), 1 part by weight of ozone-treated carbon nanotubes by melt mixing at 60 rpm for 20 minutes at 180 ℃ to prepare a conductive polymer composition. .

<Example 2>

With respect to the conditions in the ozone generator 3, the amount of ozone generation 8 g / h and the ozone concentration 23 mg / l are set, and carbon nanotubes (purity; 40 to 99%, length; 10 to 50 µm, diameter; 10 to 10) 20 nm of ILJIN Nanotech Co., Ltd. was added thereto, followed by direct ozone treatment for 4 hours. Thereafter, based on 100 parts by weight of pure high-density polyethylene (Honam Chem Co., Tm: 135 ° C), except that it is mixed with 2 parts by weight of the ozone-treated carbon nanotubes, the same conducting as in Example 1 The polymer was prepared.

<Example 3>

With respect to the conditions in the ozone generator 3, the amount of ozone generation 8 g / h and the ozone concentration 23 mg / l are set, and carbon nanotubes (purity; 40 to 99%, length; 10 to 50 µm, diameter; 10 to 10) 20 nm of ILJIN Nanotech Co., Ltd. was added thereto, followed by direct ozone treatment for 6 hours. Thereafter, with respect to 100 parts by weight of pure high density polyethylene (Honam Chem Co., Tm: 135 ° C.), except that it was mixed with 3 parts by weight of the ozone-treated carbon nanotubes, the same conducting as in Example 1 was conducted The polymer was prepared.

<Example 4>

With respect to the conditions in the ozone generator 3, the amount of ozone generation 8 g / h and the ozone concentration 23 mg / l are set, and carbon nanotubes (purity; 40 to 99%, length; 10 to 50 µm, diameter; 10 to 10) 20 nm of ILJIN Nanotech Co., Ltd. was added thereto, followed by direct ozone treatment for 8 hours. Thereafter, with respect to 100 parts by weight of pure high density polyethylene (Honam Chem Co., Tm: 135 ° C), except that it was mixed with 4 parts by weight of the ozone-treated carbon nanotubes, the same conducting as in Example 1 The polymer was prepared.

Example 5

With respect to the conditions in the ozone generator 3, the amount of ozone generation 8 g / h and the ozone concentration 23 mg / l are set, and carbon nanotubes (purity; 40 to 99%, length; 10 to 50 µm, diameter; 10 to 10) 20 nm of ILJIN Nanotech Co., Ltd. was added thereto, followed by direct ozone treatment for 8 hours. Thereafter, with respect to 100 parts by weight of pure high density polyethylene (Honam Chem Co., Tm: 135 ° C.), except that it was mixed with 5 parts by weight of ozone-treated carbon nanotubes, the same conducting as in Example 1 was conducted The polymer was prepared.

Comparative Example 1

A conductive polymer was prepared in the same manner as in Example 1, except that ozone treated carbon nanotubes were not used.

2. Fabrication of PTC Devices

<Examples 6 to 10>

After selecting the conductive polymer prepared in Example 1, and fused the conductive metal foil 50 μm thick on both sides by a hot-press method, it is cut into a measuring size, and can be connected to a power supply source. PTC electrodes 6 were prepared by adhering two electrodes with conductive adhesive. At this time, the produced PTC device was circular, the total thickness was 1 cm in diameter, and the thickness was 1.0 mm. Hereinafter, except that the conductive polymers prepared in Examples 2 to 5 were selected and used, PTC elements 7 to 10 were prepared in the same manner as described above.

Comparative Example 2

A PTC device was fabricated in the same manner as in the above method, except that the conductive polymer prepared in Comparative Example 1 was selected and used.

Experimental Example 1 Elemental Analysis According to Treatment Time of Ozone Treated Carbon Nanotubes

For the conductive polymer containing the ozonated carbon nanotubes prepared in Examples 1 to 5 and Comparative Example 1, in order to observe the content of constituents with respect to the ozone treatment time of the carbon nanotubes, elemental analyzers (Fisons EA-1108) was used to determine the content of carbon and oxygen. The results are shown in Table 1 .

Elemental Analysis Results of Ozone Treated Carbon Nanotubes   Treatment time element content Comparative Example 1 Example 1 Example 2 Example 3 Example 4 0 hours 2 hours 4 hours 6 hours 8 hours carbon(%) 97 91 90 89 88 Oxygen(%) 0.34 4.88 5.98 6.02 6.73

As shown in Table 1, in proportion to the treatment time of the ozonated carbon nanotubes, the oxygen content increased on the surface of the prepared conductive polymer.

Experimental Example 2 Surface Analysis of Ozone Treated Carbon Nanotubes

According to the ozone treatment time of the carbon nanotubes used in Examples 1 to 5, the functional group change on the polymer surface was observed through the FT-IR spectrum.

After the pulverized and mixed conductive polymer and KBr powder prepared in Examples 1 to 5 and Comparative Example 1, to produce a pellet by pressurizing it, using a FT-IR spectrometer (Hartmann & Brawn Model Bomen MB 102) 4000 ~ It was measured in the range of 400 cm ^-1 . The results are shown in FIG. 3 .

As shown in FIG. 3, the growth of oxygen-containing functional groups (O—H, C═O and C—O) was observed in proportion to the ozone treatment time.

Experimental Example 3 Resistance and PTC Strength Measurement

With respect to the PTC device using the ozonated carbon nanotubes prepared in Examples 1 to 5, the resistance and the PTC strength were measured as follows.

After connecting the manufactured PTC device to a digital multimeter, the change in the temperature-resistance curve was measured at a temperature rising rate of 2 ° C./min in a temperature-controlled oven. Figure 4 shows the temperature-resistance behavior of the amount of carbon nanotubes used in PTC devices manufactured using ozone-treated carbon nanotubes, Figure 5 is a PTC device manufactured using ozone-treated carbon nanotubes, The temperature-resistance behavior of ozone treatment time of carbon nanotubes is shown. At this time, the PTC strength is calculated by Equation 1 shown in Table 2. In the following, ρ _max is the maximum resistivity value, ρ _RT is the resistivity value at room temperature.

PTC Strength of PTC Devices Containing Ozone-treated Carbon Nanotubes   Processing time Ozone treatment time of carbon nanotubes during the manufacture of conductive polymers 0 hours 2 hours 4 hours 6 hours 8 hours Comparative Example 2 Example 6 Example 7 Example 8 Example 9 PTC Century 10 ² 10 ² 10 ^3.2 10 ^3.5 10 ³

Figure 4 shows the temperature-resistance behavior with respect to the amount of carbon nanotubes used in PTC devices manufactured using ozone-treated carbon nanotubes, preferably 2 to 5 parts by weight of carbon nanotubes, at a specific temperature (ρ _RT) value of ^2-10 and 10 and ³ ohm cm, the PTC intensity change from room temperature to the melting point (Tm) + 5 ℃ range of the polyolefin-based resin was observed with 10 ^{4-10 5.} In addition, no negative temperature coefficient (NTC) phenomenon that occurs for a long time at a temperature above the melting point was observed. Accordingly, the PTC device of the present invention exhibits excellent PTC characteristics having a small resistivity at room temperature and a high resistivity at the melting point by using a small amount of ozone-treated carbon nanotubes as conductive fillers, and an NTC phenomenon generated after overcurrent blocking. This was removed.

5 is a temperature-resistance behavior of ozone treatment time of carbon nanotubes in a PTC device manufactured using ozonated carbon nanotubes, and has a specific resistance (ρ _RT ) of 10 ² ohm · cm or less at room temperature. The maximum specific resistance was 10 ⁶ to 10 ⁸ ohm · cm and the change in PTC intensity was observed to be 10 ² to 10 ^3.5 .

Therefore, in the PTC device of the present invention, when ozone treatment of the surface of the carbon nanotubes for 2 to 8 hours, the maximum specific resistance increased with increasing ozone treatment time. That is, as the ozone treatment time increases, the functional group containing oxygen on the surface of the carbon nanotubes increases, thereby reducing the electric conductivity inherent in the carbon nanotubes and promoting the breakdown of the conduction network between the carbon nanotubes at the melting point of the polyolefin resin. The result was that the specific resistance value was increased. Accordingly, it is possible to provide a PTC device having excellent PTC strength and removing NTC phenomenon generated after overcurrent blocking due to an increase in the maximum resistivity value.

As described above, the present invention provides a conductive polymer composition for PTC devices using ozone-treated carbon nanotubes as a conductive filler and a PTC device using the same.                     

First, by using a small amount of conductive filler for the polyolefin resin, it is economical and can reduce side reactions such as aggregation of additives,

Second, when ozone treatment on the surface of the carbon nanotubes, the ozone treatment device and process is simple, the treatment time is shorter than the conventional electron beam irradiation or silane treatment method, there is no penetration of moisture into the composition, thereby improving the manufacturing process,

Third, after ozone treatment of the surface of the carbon nanotube, melt mixed with a polyolefin resin to prepare a conductive polymer composition for the PTC device, and then to produce a PTC device, an initiator, a catalyst or a separate catalyst used for initiating the conventional surface treatment reaction Since energy is not required, it is economical, and there is no fear of water penetration into the composition, thereby shortening the manufacturing time of the PTC device, thereby reducing the manufacturing cost.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and variations belong to the appended claims. .

Claims (9)

A conductive polymer composition for a PTC device comprising a polyolefin-based resin and a conductive filler, wherein the conductive filler is ozone-treated carbon nanotubes. The conductive polymer composition according to claim 1, wherein the conductive polymer composition for PTC device comprises 1 to 5 parts by weight of ozonated carbon nanotubes based on 100 parts by weight of polyolefin resin. The conductive polymer composition of claim 1, wherein the carbon nanotubes have a particle size diameter of 10 to 50 nm. The method of claim 1, wherein the conductive polymer composition has a specific resistance (ρ _RT ) value of 10 ² to 10 ³ ohm · cm at room temperature, and changes in PTC strength to a melting point (Tm) + 5 ° C. of the polyolefin-based polymer at room temperature. 10 ⁴ to 10 ⁵ , characterized in that the conductive polymer composition. After the carbon nanotubes were fixed to the surface of the carbon nanotubes at room temperature with ozone generation amount of 1-12 g / h and ozone concentration of 1-60 mg / l, and ozonated for 0.1-8 hours to produce carbon nanotubes, 100 parts by weight of polyolefin resin For, the method for producing a conductive polymer composition for a PTC device, characterized in that prepared by melting and mixing 1 to 5 parts by weight of the ozone treated carbon nanotubes. A PTC device, which is produced by compression-molding an electrolyte metal foil having a thickness of 30 to 50 µm on both surfaces of a conductive polymer composition for a PTC device according to claim 1, and bonding a pair of electrodes using a conductive adhesive. The said PTC element is a circular sheet form of thickness 0.5-1 mm, The said PTC element of Claim 6 characterized by the above-mentioned. The PTC device according to claim 6, wherein the PTC device has a specific resistance of 10 ² ohm · cm or less at a room temperature, and a maximum specific resistance of 10 ⁶ to 10 ⁸ ohm · cm. 7. The PTC device according to claim 6, wherein the PTC device has a PTC strength of 10 ² to 10 ^3.5 .

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