KR20130000193A - A method for manufacturing ptc heating device - Google Patents

A method for manufacturing ptc heating device Download PDF

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Publication number
KR20130000193A
KR20130000193A KR1020110060751A KR20110060751A KR20130000193A KR 20130000193 A KR20130000193 A KR 20130000193A KR 1020110060751 A KR1020110060751 A KR 1020110060751A KR 20110060751 A KR20110060751 A KR 20110060751A KR 20130000193 A KR20130000193 A KR 20130000193A
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South Korea
Prior art keywords
electrode
heating element
ptc heating
graphite
polymer
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KR1020110060751A
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Korean (ko)
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이보환
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주식회사 온스톤
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Publication of KR20130000193A publication Critical patent/KR20130000193A/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/02—Details
    • H05B3/03—Electrodes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/145—Carbon only, e.g. carbon black, graphite
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/44—Heating elements having the shape of rods or tubes non-flexible heating conductor arranged within rods or tubes of insulating material

Abstract

PURPOSE: A method for manufacturing a PTC(positive temperature coefficient heater) heating element is provided to continuously manufacture a PTC heating element with improved heating performance and lifetime properties by using a polymer composition including a molten polymer composition material and a conductive material and a surface-processed electrode conductor processed. CONSTITUTION: Solution including graphite(20) is coated on a pair of circular electrode conductors(10) arranged at a predetermined space. A polymer composition including Polymer resin, carbon block, and an additive is adhered on the electrode conductors. A PCT heating body(30) is pressure-molded in order to cover the electrode conductors. A pressure-molding processes under a condition of 100bar-400bar. An insulation cladding(40) is formed in outside of the PCT heating body.

Description

Method for manufacturing PTC heating element {A method for manufacturing PTC heating device}

The present invention can reduce the occurrence of electrical resistance at the interface between the electrode and the polymer composition according to the surface treatment of the graphite to maintain the flow of electricity to improve the heat generation performance and prevent overheating at the interface, accelerated life compared to the existing The present invention relates to a method for producing a polymer PTC device that can also increase time.

The positive temperature coefficient (PTC) heating element of the polymer is a polymer, which is produced by injecting / dispersing a large amount of conductive carbon black, which is a kind of carbon, into a high crystalline polymer material. Refers to a new concept heater molded in the form of a disk.

Such a polymer PTC heating element has no fear of overheating or fire, and has a positive (+) resistance temperature characteristic because the temperature can be controlled by itself without a separate temperature controller. In addition, the polymer PTC heating element has no length limit in the circuit configuration (infinite parallel circuit), and can independently control the output according to the local temperature change. In addition, the entire heater section functions as both a sensor and a heater (Continuous & Linear Sensor), and by soft switching, it saves about 30% energy and extends the life of electric products.

The structure of the polymer PTC heating element includes an electrode conductor 1, a polymer PTC heating element 2, an insulating coating 3, a ground metal braid 4, and an outer coating 5, as shown in FIG. do. Thus, the PTC heating element basically has a cross-sectional structure shown in FIG. 1B. In FIG. 1B, two electrodes are arranged at both sides at predetermined intervals to form a pair of electrode conductors 1, the outside of which is insulated from the polymer PTC heating element 2 made of carbon black and a polymer composite material. Covering 3.

However, the existing polymer PTC heating element has a problem that the electrical resistance occurs at the interface between the polymer composition and the electrode conductor. That is, the linear thermal expansion coefficient of polyethylene as the base material of the polymer composition is 0.2 mm / m ℃ in the 23 ~ 80 ℃ region, whereas the thermal expansion coefficient of copper as an electrode material is 0.016 mm / m ℃ is different from each other. Therefore, due to the difference in the coefficient of thermal expansion between the two interfaces, due to repeated on-off switching operation, a microscopic dislocation phenomenon occurs at the interface between the copper-based electrode and the polymer composition that has been fused (closed).

In other words, the voltage applied to the conductive polymer composition, which is a heat generating resistor, is lower than the design value, so that the heat generation performance is lowered, and the thermal fatigue of the polymer composition at the portion contacting the interface is increased due to local overheating at the interface where the resistance is relatively increased. . As a result, a decrease in heat generation function occurs due to a decrease in efficiency of the electric flow passing through the interface. In this way, the separation of the electrode is accelerated at the interface, the power supply is not smooth, the non-uniformity of the heat generation performance occurs in the longitudinal direction and the amount of heat generated gradually decreases, the acceleration of the separation of the electrode and the polymer composition occurs.

On the other hand, in order to solve this problem occurring in the polymer PTC heating element, there is a method of modifying the product structure or material so that the thermal expansion and shrinkage rate of the PTC composition is the same as the metal electrode conductor.

However, the above method has a problem of developing a PTC device based on a metal or a ceramic, and even if such a device is developed, the PTC function, that is, the PTC intensity is weak, so there is no practical value.

As another method, there is a method of modifying the product structure or material so that the thermal expansion rate of the electrode material is the same as that of the polymer composition.

To this end, there is a method for developing a polymer-based electrode, but it is difficult to add a large amount of conductive particles to the polymer material with the current technology. Therefore, the method has a low electrical conductivity, has a low practicality as an electrode, and has a problem in that the cost is great to achieve the conductivity of the polymer electrode close to metal. Alternatively, there is a method of designing a product to synchronize the expansion and contraction motion of the polymer composition by modifying the structure of the metal electrode conductor into spiral or woven, but this method is also used for the use of the metal electrode conductor. This leads to an increase in cost and a difficult problem of molding.

As described above, according to the existing method, due to the difference in the coefficient of thermal expansion of the polymer composition and the electrode conductor, the separation of the electrode at the interface is accelerated and the heat generation performance gradually decreased in the longitudinal direction due to the loss of the applied voltage.

Accordingly, an object of the present invention is to reduce the occurrence of electrical resistance at the interface between the electrode and the polymer composition according to the specific surface treatment of the electrode to sustain the flow of electricity and to prevent the deterioration of the heating function and overheating at the interface, and accelerated compared to the conventional An object of the present invention is to provide a method for producing a polymer PTC heating element that can also increase the life time.

In addition, the present invention is to provide a method for manufacturing a PTC heating element to maintain the electrical adhesion of the carbon mixture coated on the electrode surface when the slip occurs at the interface between the circular electrode conductor and the polymer composition.

Another object of the present invention is to provide a high molecular weight PTC heating element manufactured by the above method, which is excellent in heat generation performance and excellent in service life.

The present invention (a) coating a solution containing graphite on a pair of circular electrode conductors arranged at predetermined intervals,

(b) pressure forming the PTC heating element to cover the electrode conductor by adhering a polymer composition comprising a polymer resin, carbon black and an additive to the graphite-coated electrode conductor;

(c) forming an insulating coating on the outside of the PTC heating element,

The electrode conductor provides a method of manufacturing a PTC heating element, which is made of concentric circles by twisting a nickel plated copper wire having a circular cross section at regular intervals.

The solution including the graphite of (a) may further include one or more metal powder particles selected from the group consisting of carbon yarn, carbon black and nickel.

In addition, the method of the present invention, the step of (a) and the step (b), the step of pressing the graphite-coated electrode conductor obtained in step (a), and heating using an induction heating method or a radiation heating method It may further include.

In addition, the present invention is prepared by the above method,

A pair of circular electrode conductors comprising a first electrode and a second electrode arranged at predetermined intervals,

Graphite having a predetermined thickness coated on the outside of the first electrode and the second electrode of the circular electrode conductor,

A PTC heating element formed to surround the pair of circular electrode conductors including the graphite coated first electrode and the second electrode, and

It provides a PTC heating element comprising an insulating coating formed on the outside of the PTC heating element.

Hereinafter, the present invention will be described in more detail. However, the terms or words used in the present specification and claims should not be construed as being limited to the ordinary or dictionary meanings, and the inventors appropriately define the concept of terms in order to explain their own invention in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can.

In the present invention, by minimizing the electrical resistance at the interface between the polymer composition and the circular electrode conductor made of metal, it prevents the fine separation phenomenon at the interface and smooth the flow of electricity to improve the heat generating function of the polymer PTC heating element To provide a manufacturing method.

That is, when the polymer PTC heating element is used for a short time, the adhesive force is improved by pressure molding between the electrode coated with the carbon mixture and the polymer composition, and the instantaneous electrode conductor heating process, so that the electrical resistance at the interface does not significantly increase.

However, when the heating element is used for a long time, the concentration and fatigue of stress at the interface with the electrode material having a relatively low expansion rate is repeated due to the repetition of turning on and off the power supply and repeating the expansion and contraction of the polymer composition. This increase results in a rapid increase in fine cracks and physical breakdown and consequently electrical resistance.

However, according to the present invention, when the separation occurs at the interface, the graphite (graphite) coated on the surface of the circular electrode conductor smoothly slips between the circular electrode conductor and the polymer composition at the interface, and at the same time lowers the electrical resistance at the interface. It serves to maintain the contact can effectively extend the service life of the heating element. In addition, the conventional planar heating element has a problem that the flow of the electrode is broken when the polymer composition is separated from the interface of the electrode conductor, but in the case of the present invention, since the circular electrode conductor is used and graphite coating is applied thereto, the electrical resistance at the interface is increased. Can be lowered to maintain electrical contact.

Accordingly, an essential aspect of the present invention is to provide a method for manufacturing a PTC heating element in which a carbon mixture coated on an electrode surface maintains electrical adhesion when slippage occurs at an interface between a circular electrode conductor and a polymer composition.

In another aspect, the present invention is characterized by manufacturing a polymer PTC heating element using a conductive composite material formulation and process development technology, electrode affinity improvement technology, and polymer molding technology.

According to one preferred embodiment of the present invention, (a) coating a solution containing graphite on a pair of circular electrode conductors arranged at predetermined intervals, (b) to the electrode coating coated graphite obtained above Bonding a polymer composition comprising a polymer resin, carbon black, and an additive to pressurize the PTC heating element to surround the electrode conductor; and (c) forming an insulating coating on the exterior of the PTC heating element. Is a method for manufacturing a PTC heating element, which is made of concentric circles by twisting a nickel plated copper wire having a circular cross section at regular intervals.

In order to manufacture the PTC heating element, the present invention is a raw material combination step, the surface modification of the electrode and the compounding step of the polymer composition, the storage step, the adhesion step of the polymer composition and the surface-treated electrode conductor, crystallization and cooling of the polymer through curing Step, and a winding step (FIG. 2).

In the raw material combining step, an emulsion mixing method and a dispersion method by a roll mill are performed. Subsequently, in the surface modification of the electrode and the compounding step of the polymer composition, the above-described steps (a) and (b) may be performed. In addition, when blending the polymer composition, a screw arrangement suitable for the carbon black structure and rheology of the polymer included in the composition may be set, and the screw dispersion may be used for the polymer blend.

In more detail, in order to perform step (a), the present invention prepares two circular electrode conductors made of metal for surface treatment of electrodes and uses them as first and second electrodes. That is, the "circular electrode conductor" referred to in the present invention includes a "circular electrode" used in a PTC heat transfer element, and includes a first electrode and a second electrode made of a conductive metal. Such circular electrode conductors may comprise copper, silver, tin, aluminum, or alloys thereof, more preferably copper. In particular, it is preferable that the circular electrode conductor includes a circular shape in which a nickel plated copper wire having a circular cross section is twisted at several intervals to be close to a concentric circle in order to smooth the sliding of the electrode conductor at an interface.

In addition, in the present invention, for the surface treatment of the electrode conductor, a solution containing graphite is prepared. Subsequently, the present invention arranges the first electrode and the second electrode at predetermined intervals, and then coats a solution containing the graphite thereon. Through this process, the surfaces of the first electrode and the second electrode are coated with graphite, thereby reducing the interface resistance with the polymer composition, thereby facilitating the flow of electricity even when the polymer composition is separated from the electrode. In addition, the coating thickness of the graphite is not particularly limited, but may be 1 to 50 ㎛.

When the coating process of the graphite is completed, it can be used in the next step after the drying process according to a conventional method.

The solution containing graphite may include graphite and water and may be a suspension. In addition, the concentration of the solution containing the graphite is not particularly limited, but the solid content of the graphite is 30 to 70% by weight can improve the coating properties. In this case, the graphite used in the present invention can effectively protect the magnetic particles therein from harsh environments such as high temperature and chemical solvents such as acids and the like compared to coating of other materials. In addition, the graphite is a carbon crystal is arranged in a plane having a predetermined crystal structure, it is possible to ensure a sliding phenomenon more effectively on the surface of the electrode. In addition, the graphite coating can double the flow of current of the electrode, thereby further improving the heat generating characteristics. In this case, the solution containing the graphite of (a) may further include one or more metal powder particles selected from the group consisting of carbon yarn, carbon black and nickel, the content of which is 100 parts by weight of the solution containing graphite 0.1 to 10% by weight relative to the total amount. The graphite and metal powder particles may have an average particle diameter of 20 nm to 200 nm.

In addition, when the above process is completed, the electrode wire and the polymer composition is transferred to the storage tank, and then moved through the transfer line to bond the polymer composition and the electrode conductor and undergo a crystallization and cooling process to obtain the polymer PTC heating element of step (b). Form.

That is, in step (b), the polymer composition may be cured by a conventional method to bond the circular electrode conductor and the polymer composition.

At this time, the polymer composition is not particularly limited in composition and may be used a conventional material used in the manufacture of the PTC heating element. As a preferred example, the polymer composition may include a polymer resin, carbon black, and an additive.

A normal thermoplastic resin can be used for the said polymer resin, The kind is not specifically limited. Examples of the polymer resin include polyethylene resin, polypropylene resin, polyvinylacetate, polycaprolactone polyesters, polyamide, polyethylenevinylacetate copolymer, ethylenebutyl acrylate and polyisobutylene resin and polybutadiene resin. It may include one or more thermoplastic polymer resin selected from the group consisting of. In addition, the content may be used in 10 to 70% by weight based on the total polymer composition.

In addition, the carbon black may be used having an average particle diameter of 50 to 300nm, the content may be used in 25 to 85% by weight based on the total polymer composition.

The additives may also use generally known components, for example, a group consisting of a curing agent, UV stabilizer, antioxidant, filler, lubricant, flame retardant, coupling agent, ultraviolet absorber, pigment, dye, plasticizer, tackifier and surfactant. It may include one or more selected from. The content of the additive may be used in the remaining amount relative to the entire polymer composition, the content range is not particularly limited.

Subsequently, an insulating coating may be formed on the outside of the polymer PTC heating element in a conventional manner to provide a PTC heating element including the structure shown in FIG. 3.

3, the polymer PTC heating element of the present invention includes an electrode conductor 10 including a first electrode and a second electrode disposed at predetermined intervals, graphite 20 formed to a predetermined thickness on the outside thereof, and A polymer PTC heating element 30 including carbon black and a polymer composite material surrounding the graphite 20 and filling the electrodes, and an insulating coating 40 surrounding the outside thereof. At this time, the graphite 20 means that it is formed in the form of a layer having a predetermined thickness, as shown in FIGS.

Accordingly, according to another embodiment of the present invention, a pair of circular electrode conductors manufactured by the above method and including a first electrode and a second electrode disposed at predetermined intervals, the first electrode and the second electrode of the circular electrode conductor Graphite having a predetermined thickness coated on the outside of the electrode, a PTC heating element formed to surround the pair of circular electrode conductors including the graphite-coated first electrode and the second electrode, and an insulation coating formed on the outside of the PTC heating element A PTC heating element is provided.

In the polymer PTC insulating device having such a structure, when a voltage is applied, the graphite particles can maintain the electric flow between the polymer composition and the electrode even if the circular electrode is slightly separated from the polymer composition. That is, referring to FIG. 4, in the present invention, medium particles exhibiting conductivity close to metal at an interface between the circular electrode conductor 10, which is a metal component, and the polymer PTC heating element 30 including carbon black and a polymer composite material, are in contact with each other. By using the raw graphite 20, the potential barrier does not occur even in the thermal expansion shrinkage bonding (sliding operation) in the longitudinal direction. Accordingly, the present invention does not form a potential barrier even when the polymer composition and the circular electrode conductor are displaced due to different thermal expansion rates, thereby providing a product capable of minimizing the potential difference between both sides of the interface.

On the other hand, according to the present invention, after the water-soluble graphite is coated, it may be directly bonded with the polymer composition to form a PTC heating element. However, for more efficient surface treatment of the electrode, the method of the present invention, between the steps (a) and (b), press-molded the graphite-coated electrode conductor obtained in step (a), and induction heating method or The method may further include heating using a radiant heating method. Through this step, the present invention can provide an effect of improving the adhesion of the electrode conductor and the polymer composition. The induction heating method may be a method of heating a metal object using conventional electromagnetic induction. For example, induction heating is performed by placing an induction heating substrate on which one or more coils are wound on an upper side, a lower side, or an upper side and a lower side of an electrode conductor, and induction heating by applying an alternating current of high frequency to the substrate. The temperature of the conductor can be raised. In addition, the radiation heating method may use a method of treating with radiant heat by heating a heat medium such as infrared rays, and the method is not particularly limited.

More preferably, the present invention may improve the adhesion between the two materials in the instantaneous high temperature heating process by induction heating together with the pressurization process of 100 to 400 bar during extrusion molding with the polymer composition.

Therefore, the present invention may further include a step of press forming the electrode conductor coated with graphite obtained in step (a) and instantaneous heating by induction heating between steps (a) and (b). . The pressure molding method is not particularly limited, but a pressure extrusion molding method using a special die capable of pressing up to 700 bar may be used.

Further, according to the present invention, the method may further include sequentially forming a ground metal braid and an outer sheath outside the insulation sheath after step (c).

In the present invention, it is possible to significantly improve the flow characteristics of the electrode compared to the conventional through the surface treatment of the circular electrode using graphite. Therefore, in the present invention, by using a polymer composition including a molten polymer composite material and a conductive material, and the electrode conductor subjected to the surface treatment, a PTC heating element having excellent heat generation performance and improved lifetime characteristics can be continuously manufactured. Can be.

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical spirit of the present invention, the present invention includes matters described in such drawings. It should not be construed as limited to.
Figure 1a shows the structure of a typical polymer PTC heating element.
FIG. 1B is a simplified cross-sectional view of the structure of FIG. 1A.
Figure 2 shows a simplified view of the manufacturing process of the polymer PTC heating element according to the present invention.
Figure 3 briefly shows a cross-sectional view of the polymer PTC heating element according to the present invention.
4 is a simplified side view of the polymer PTC heating element of the present invention.
Figure 5a shows a SEM photograph of the cross section of the polymer PTC heating element according to Comparative Example 1.
Figure 5b shows the heat generation performance results of the polymer PTC heating element according to Comparative Example 1.
6 and 7 show SEM and EDS analysis results of the polymer PTC heating element according to Comparative Example 1 and Example 1. FIG.
8 is a graph showing a comparison between accelerated life test results of polymer PTC heating elements of Comparative Example 1 and Example 1. FIG.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through a specific embodiment of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

< Comparative example  1>

Using a polymer resin composition and an electrode conductor (copper) comprising polyethylene resin, carbon black and additives, a polymer PTC heating element having the structure shown in FIGS. 1A and 1B was manufactured in a conventional manner.

< Example  1>

Aquadag 22%, a water-soluble graphite solution, was purchased from Acheson Colloid, USA, and the surface coating treatment (coating thickness: 30 μm) of the electrode conductor was performed.

The electrode conductor was used to make the copper conductor close to the concentric circle by twisting the nickel plated copper wire having a circular cross section at regular intervals in order to smooth the sliding of the electrode conductor at the interface. In addition, the first electrode and the second electrode, respectively, were coated with the graphite solution on the outside and dried.

Thereafter, the graphite coated electrode conductors were arranged at regular intervals as the first electrode and the second electrode as shown in FIG. 3.

In addition, a conventional polymer resin composition comprising 59 wt% polyethylene resin, 40 wt% carbon black, and 1 wt% antioxidant was used to surround the outside of the graphite coated electrode conductor (first electrode and second electrode). So that they are filled together. Then, an insulating coating was formed on the outside of the polymer PTC heating element shown in FIG. 3.

< Experimental Example  1>

(1) Heat generation performance evaluation

A SEM photograph was taken of the cross section of the polymer PTC heating element of Comparative Example 1 and shown in FIG. 5A. In addition, in order to evaluate the heat generation performance, the cycle test was performed by using the five PTC heating elements of Comparative Example 1 as a terminal block and connecting them to 220V through a timer, and then applying <15 minutes voltage and 15 minutes voltage blocking>. Proceeded. In addition, the exothermic performance was performed at room temperature and in the air to maximize thermal expansion and contraction of the PTC heating element. The evaluation results are shown in Figure 5b.

Referring to FIG. 5A, a fine separation phenomenon occurs at the interface between the polymer composition and the copper-based electrode conductor.

For this reason, as shown in FIG. 5B, in the case of Comparative Example 1, the detachment of the electrode at the interface accelerated as time passed, and the heat generation performance gradually decreased in the longitudinal direction due to the loss of the applied voltage.

At this time, the interface resistance analysis method was measured and calculated in the following order.

(1) potential barriers created by interfacial resistance

Quantify the electrical contact resistance by comparing the currents flowing by applying different voltages exceeding the voltage below the V threshold that can penetrate the potential barrier formed between the electrode and the polymer composition. It was.

(2) Resistance measurement by applying low voltage (9V) (Rp)

After applying 9V using a multimeter (multImeter), the value of the current flowing through the electrodes of the PTC heating element was measured and converted into resistance was recorded (R 9 ).

(3) Resistance measurement by applying commercial voltage (220V) (Ra)

After applying 220V by using a voltage stabilizer (AVR), the current value flowing through the electrodes of the PTC heating element was measured and converted into a resistance was recorded (R 220 ).

(4) Contact Resistance Index Output (Rp / Ra)

remind R 9 The ratio of and R 220 was obtained and called the contact resistance index.

(2) accelerated life test

The products of Comparative Examples 1 and 1 were subjected to accelerated life tests over 6 months. Then, the experimental results are shown in Tables 1 and 2 below.

Comparative Example 1 Voc Resistance (ohm / m) Instantaneous current (A / m) Stable current (A / m) Rp / Ra Before the test 346 0.82 0.25 1.28 6 months later 1,023 0.37 0.17 1.72

Example 1 Voc Resistance (ohm / m) Instantaneous current (A / m) Stable current (A / m) Rp / Ra Before the test 371 0.72 0.24 1.21 6 months later 359 0.75 0.26 1.22

Through the results of Tables 1 and 2, Comparative Example 1 rapidly increased the electrical resistance due to fine cracks and physical separation when used for a long time.

On the other hand, in Example 1 of the present invention, even if it is used for a long time, the slip between the electrode conductor and the polymer composition is smooth, so that the electrical resistance at the interface is low, so it can be seen that the service life of the heating element is extended.

< Experimental Example  2>

For the polymer PTC heating elements of Comparative Example 1 and Example 1, the carbon content around the electrode was analyzed by SEM and EDS (energy dispersive spectrometer) analysis, and the results are shown in FIGS. 6 and 7.

6 and 7, it can be seen that the existing Comparative Example 1 was not coated with graphite, and thus the carbon content around the electrode was 4.79 wt%, which is less than 7.82 wt% of Example 1 of the present application.

< Experimental Example  3>

Accelerated life test

The rate of change of physical properties of the polymer material is most sensitively determined by the temperature (T) at which the polymer material is exposed.

Since the typical operating voltage is 220 Vac, several higher voltages are selected to measure the time required to change the physical properties of each voltage, and a unique method of estimating the change time is required at the normal voltage of 200V.

Therefore, the accelerated life test was performed for the polymer PTC heating elements of Comparative Example 1 and Example 1. The property change standard set in the above test method was set such that the exothermic performance was reduced by 10% or 25% compared to the initial value. , 374 and 440 Vac. In addition, when a voltage was applied to the PTC heating wire, a so-called cycling test was applied in which a voltage was applied for 15 minutes and the voltage was cut for 15 minutes for a more severe test. The test results are then shown in Tables 3 and 4.

In addition, the accelerated life test using the Arrhenius method was tested for the polymer PTC heating elements of Comparative Example 1 and Example 1, and the results are shown in FIG. 8.

Comparative Example 1 Voc 200 330 374 440 10% reduction 50,000 840 360 144 25% reduction 90,000 1896 720 240

Example 1 Voc 200 330 374 440 10% reduction 90,000 2780 840 144 25% reduction 400,000 4728 1416 360

As shown in Tables 3 and 4 and FIG. 8, it can be seen that Example 1 of the present invention has better acceleration life for each applied voltage than Comparative Example 1, and thus can be effectively used as a PTC heating wire.

1, 10: electrode conductor
20: graphite
2, 30: polymer PTC heating element
3, 40: insulation cloth
4: metal braid for grounding
5: outer cloth

Claims (9)

(a) coating a solution comprising graphite on a pair of circular electrode conductors arranged at predetermined intervals,
(b) pressure forming the PTC heating element to cover the electrode conductor by adhering a polymer composition comprising a polymer resin, carbon black and an additive to the graphite-coated electrode conductor;
(c) forming an insulating coating on the outside of the PTC heating element,
Wherein the electrode conductor is made of concentric circles by twisting a nickel plated copper wire having a circular cross section at regular intervals, PTC manufacturing method of the heating element. The method of claim 1, wherein the solution of graphite (a) further comprises one or more metal powder particles selected from the group consisting of carbon yarn, carbon black, and nickel. The method according to claim 1, wherein the step (a) and (b) is carried out by pressing the graphite-coated electrode conductor obtained in step (a) and heating by using an induction heating method or a radiation heating method. The method of manufacturing a PTC heating element further comprising. The method of claim 3, wherein the pressure forming is performed by pressure extrusion under a condition of 100 to 400 bar. The method of claim 1, wherein the conductive metal comprises a first electrode and a second electrode formed of a conductive metal. The method of claim 1, wherein the polymer resin is polyethylene resin, polypropylene resin, polyvinylacetate, polycaprolactone polyesters, polyamide, polyethylenevinylacetate copolymer, ethylenebutyl acrylate and polyisobutylene resin and polybutadiene A method for manufacturing a PTC heating element comprising at least one thermoplastic polymer resin selected from the group consisting of resins. The method of claim 1, wherein the additive comprises at least one selected from the group consisting of a curing agent, a UV stabilizer, an antioxidant, a filler, a lubricant, a flame retardant, a coupling agent, an ultraviolet absorber, a pigment, a dye, a plasticizer, a tackifier, and a surfactant. Method for producing a PTC heating element comprising. The method of claim 1, wherein the method further comprises the step of sequentially forming a ground metal braid and an outer sheath outside the insulating sheath after step (c). Prepared by the method according to any one of claims 1 to 8,
A pair of circular electrode conductors comprising a first electrode and a second electrode arranged at predetermined intervals,
Graphite having a predetermined thickness coated on the outside of the first electrode and the second electrode of the circular electrode conductor,
A PTC heating element formed to surround the pair of circular electrode conductors including the graphite coated first electrode and the second electrode, and
PTC heating element comprising an insulating coating formed on the outside of the PTC heating element.
KR1020110060751A 2011-06-22 2011-06-22 A method for manufacturing ptc heating device KR20130000193A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101373570B1 (en) * 2013-02-28 2014-03-12 노신정 Graphite composition coated aluminium busbar and switchgear having the same
US10057943B2 (en) 2013-12-10 2018-08-21 Hyundai Motor Company Electrode for carbon fiber plate heating element and method for producing the same
WO2019031673A1 (en) * 2017-08-11 2019-02-14 주식회사 에스에이치테크 Heating unit and heating module comprising same
KR20220159079A (en) * 2021-05-25 2022-12-02 (주)오토인더스트리 Carbon-polymer hybrid heating wire, method for manufacturing the same and heating article comprising the same
KR102527471B1 (en) * 2023-01-06 2023-05-03 (주) 이앤에스텍 Positive temperature coefficient heating cable for drying in bio and pharmaceutical field

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101373570B1 (en) * 2013-02-28 2014-03-12 노신정 Graphite composition coated aluminium busbar and switchgear having the same
US10057943B2 (en) 2013-12-10 2018-08-21 Hyundai Motor Company Electrode for carbon fiber plate heating element and method for producing the same
WO2019031673A1 (en) * 2017-08-11 2019-02-14 주식회사 에스에이치테크 Heating unit and heating module comprising same
KR20220159079A (en) * 2021-05-25 2022-12-02 (주)오토인더스트리 Carbon-polymer hybrid heating wire, method for manufacturing the same and heating article comprising the same
KR102527471B1 (en) * 2023-01-06 2023-05-03 (주) 이앤에스텍 Positive temperature coefficient heating cable for drying in bio and pharmaceutical field

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