JPH10270203A - Organic ptc composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a circuit from an overcurrent by a method, wherein carbon blacks(CB) plated with metal and kept like a cluster of grapes in structure are dispersed as charged particles in organic polymer. SOLUTION: Carbon blacks(CB), plated with metal and kept like a cluster of grapes in structure, are dispersed as charged particles in organic polymer for the formation of an organic PTC(positive temperature coefficient) composition. Metals attached to carbon particles are set to 1 to 8 wt.% of CB in amounts. One or more kinds of particles selected out of Ni-plated CB particles, Cu-plated CB particles, Ag-plated CB particles, Sn-plated CB particles and Au-plated CB particles are used as CB particles of metal-plated CB particles dispersed into organic polymers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric material, and more particularly, to a property of a PTC characteristic (Positive Temperatu
re Coefficient)], that is, P
It relates to a TC composition, especially an organic PTC composition.

[0002]

2. Description of the Related Art PTC compositions have the above-mentioned PTC characteristics and include household and industrial wiring overcurrent protection elements, heaters that stop heating when the temperature rises to a certain temperature, positive temperature coefficient thermistors, thermal sensors, batteries, and the like. It is used as a circuit protection element or the like that limits the current of the circuit by the PTC characteristic when the circuit is short-circuited and restores the circuit when the cause of the short-circuit is removed. When this PTC composition is used as an overcurrent or overheat protection element or the like that exhibits the self-temperature control action as described above, for example, the composition is molded and at least two electrodes are electrically connected to the PTC composition to form a PTC composition. Used as an element.

[0003] Also, various substances have been developed as PTC compositions, one of which is BaTiO ₃ .
Addition of a trivalent or trivalent metal oxide is conventionally known. However, since the NTC characteristic is developed immediately after the PTC characteristic is developed, it takes 1 msec. There is a problem that a current flows below. Therefore, an organic polymer such as polyethylene (abbreviated as PE), polypropylene or ethylene-acrylic acid copolymer,
A material in which conductive particles such as carbon black (abbreviated as CB), carbon fiber, graphite or metal fine particles are dispersed has been developed. The organic PTC composition is generally produced by adding a necessary amount of conductive particles to one or more resins used as an organic polymer and kneading the resultant.

As conductive particles of an organic PTC composition, C
When B, carbon fiber or graphite is used, the initial resistivity cannot be sufficiently reduced,
The PTC characteristics are also small, and the current limiting performance cannot be sufficiently improved. In addition, P containing conventional known metal particles
Although the TC composition can be expected to reduce the initial resistivity, when it is used under a large current and a high voltage, it causes an internal arc phenomenon (a minute arc is generated between the conductive particles) and causes a failure such as electric breakdown of the element. was there. In addition, 4-60
No. 58 discloses an organic PTC composition containing CB particles whose surfaces are partially plated with metal as conductive particles. The resistance temperature characteristics of the PTC element using the metal-plated CB and the PTC element using the CB without plating show similar temperature characteristics, but the resistance value of the PTC element is the same as that of the plated CB. The organic composition used is much smaller. Further, it is described that the resistance value decreases as the amount of metal plated on the CB increases, and the resistance can be arbitrarily adjusted by the amount of metal plating on the CB.

However, the present inventors have further studied and investigated in detail the PTC composition using the metal-plated CB, and found that the resistivity is high despite the large amount of metal adhesion. FIG. 2 is a diagram showing the relationship between the copper plating amount (wt%) of CB and the resistivity of the PTC element.
It can be seen that, when the amount of copper plated on the CB is too large, the resistivity increases conversely as compared with the case of using CB alone. CB
The resistivity when the amount of copper plating was 70 wt% increased to about 6 times that without plating. This is presumably because the large amount of metal adhered destroyed the bunched structure of the CB grape, resulting in poor electron conductivity. In addition, when the amount of deposited metal increases, when used under high current and high voltage, an internal arc phenomenon occurs, and the metal plated by the internal arc at the time of interruption is melt-connected to form a local conductive circuit, and the current is reduced. Is concentrated, heat is locally generated and the element is destroyed, and the overcurrent cutoff characteristic is deteriorated.

[0006]

As described above, an organic PT using metal-plated CB particles as conductive particles.
It has been thought that the C composition can reduce the resistivity of the PTC element at room temperature as compared with the unplated CB alone, and the resistivity decreases as the amount of adhered metal increases. On the other hand, when the amount of metal adhered is too large, the normal resistivity increases, the conductivity deteriorates, the peak current at the time of overcurrent interruption cannot be reduced, and the current interruption performance cannot be sufficiently improved. there were. In addition, when used under a large current and high voltage, as in the case of using metal particles, an internal arc phenomenon occurs, the metal melts and a conductive circuit is locally formed, and the composition and the PTC element are destroyed. For example, there is a problem in that the circuit lacks safety and reliability, and the circuit cannot be repeatedly and properly protected from overcurrent.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a low resistance and good conductivity during normal energization, can reduce a peak current at the time of overcurrent interruption, and can realize a large current. It is an object of the present invention to obtain an organic PTC composition that can protect a circuit from overcurrent without forming a conductive circuit locally even under a high voltage. That is, an object of the present invention is to obtain an organic PTC composition having excellent current interruption performance, high safety and high reliability, and which can be favorably used as, for example, a self-recovering overcurrent protection element.

[0008]

According to a first aspect of the present invention, there is provided an organic PTC composition comprising a metal plating on a surface;
It is obtained by dispersing carbon black, which has a grape-like tufted structure, as conductive particles in an organic polymer.

A second structure of the organic PTC composition of the present invention is the same as the first structure, except that the amount of metal adhered to carbon black is 1 to 8% by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The organic PTC composition according to the present invention is a carbon black having a surface coated with metal as conductive particles in an organic polymer and having a grape tufted structure. Are dispersed. Since the bunched structure of the grape CB is not impaired and maintained, the initial conductivity of the PTC element is not reduced due to the reduction of the electron conductivity due to the reduction effect of the plated low resistivity metal. Can be reduced. Therefore, during normal energization, the resistance is low and the conductivity is good, the peak current at the time of interrupting the overcurrent can be reduced, and when a large current flows, the current can be reliably interrupted and the circuit can be protected. Further, due to the excellent PTC characteristics and the high thermal conductivity of the plated metal, the overcurrent interruption time can be reduced.
The amount of the deposited metal is small enough to maintain the CB grape tufted structure, and the metal may be melted due to the internal arc phenomenon to form a local conductive circuit as in the conventional example. In addition, current flows uniformly over the entire surface of the element, and has excellent current interrupting performance. In addition, due to the good thermal conductivity of the entire composition (that is, the device) and the instantaneous blocking effect, the thermal decomposition of the organic polymer as the matrix is reduced, and a stable device with less damage even after short-circuit blocking can be obtained. It works well as a self-recovering overcurrent protection element.

When the amount of the metal adhered to the carbon black is set to 1 to 8% by weight, the above effect becomes remarkable. That is, since the amount of adhered metal is as small as 8% by weight or less, the CB grape tuft-like structure can be maintained well without impairment, and good electron conductivity can be maintained. The fusion splicing of metal due to the internal arc phenomenon can be prevented. On the other hand, since metal is attached at 1% by weight or more,
It also has the effect of reducing the initial resistivity of the PTC element, and provides good thermal conductivity. An adverse effect caused by attaching a metal is eliminated, and only a favorable effect can be expected. An excellent PTC element having excellent electronic conductivity can be provided.

The conductive particles dispersed in the organic polymer, ie, the metal-plated CB particles, are selected from, for example, Ni-plated CB particles, Cu-plated CB particles, Ag-plated CB particles, Sn-plated CB particles, Au-plated CB particles and the like. At least one or more types of particles are used. As a method of plating the CB surface, electroless plating, so-called chemical plating, is used. The particle size of the conductive particles can be appropriately selected from various types according to the use and desired characteristics of the organic PTC composition. For example, a particle having an average particle size of 50 to 100 nm is desirable. The weight of the conductive particles in the organic PTC composition is desirably 55 to 70% by weight. This facilitates uniform distribution and prevention of short circuit between electrodes,
It is possible to improve the short-circuit breaking property of the TC composition.

The organic polymer according to the present invention includes polyethylene, polyethylene oxide, polybutadiene, polyethylene acrylate, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, polyester, polyamide, polyether, polycaprolactam, fluorine Ethylene-propylene copolymer, chlorinated polyethylene, chlorosulfonated ethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, styrene-acrylonitrile copolymer, polyvinyl chloride,
Polycarbonate, polyacetal, polyalkylene oxide, polyphenylene oxide, polysulfone, and fluororesin are used, and a blend polymer of these alone or a mixture of at least two or more selected from these is used. The type, composition ratio, and the like of the organic polymer may be appropriately selected according to desired performance, use, and the like.

In preparing the PTC composition, various additives may be mixed, if necessary, in addition to the above-mentioned organic polymer and conductive particles. Examples of the additives include flame retardants such as antimony compounds, phosphorus compounds, chlorine compounds, and bromine compounds, antioxidants, and stabilizers. The PTC composition is prepared by mixing and kneading an organic polymer, conductive particles, and other additives as required at a predetermined ratio. The organic polymer may be prepared by mixing and kneading conductive particles or both at the same time. The mixing ratio of the organic polymer and the conductive particles can be appropriately selected according to the conductive particle content of the target composition, the type of the organic polymer, and the type of kneading machine such as a Banbury mixer, a pressure kneader, or a roll mill. it can.

The PTC composition obtained according to the present invention can be used for various purposes. When used as a PTC element, the PTC composition is formed into a plate shape, for example, and an electrode plate is pressed on the back surface of the plate or a metal foil electrode is pressed by heat to form a laminate, and the laminate is formed on the electrode surface. The PTC element can be manufactured by crimping, soldering, brazing, spot welding, etc. the terminals.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but it should be understood that the present invention is by no means restricted by these. Embodiment 1 FIG. 40 parts by weight of polyethylene (abbreviated as PE; JV070H manufactured by Mitsubishi Chemical Corporation) as an organic polymer of the matrix, 60 parts by weight of metal-plated CB particles obtained by plating 5% by weight of Cu on CB (Lamp Black 101 manufactured by Degussa) as conductive particles, And 2 parts of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Geigy) were kneaded to produce an organic PTC composition. This organic PTC composition is sandwiched between nickel-plated copper foils having a thickness of 35 μm,
An organic PTC element was manufactured by thermocompression bonding to 0 × 60 × total thickness 1 mm. An overcurrent cutoff experiment was performed with the obtained organic PTC element sandwiched between electrodes. FIG. 1 shows the relationship between the element resistance (R) and the peak current (referred to as Ip) at the time of overcurrent interruption. When the room temperature resistance of this organic PTC element is 3 mΩ, 300 V, 5
The breaking current Ip for 0 kA was 8 kA.

Embodiment 2 FIG. 45 parts by weight of PE (Mitsubishi Chemical's JV070H) as an organic polymer and CB as conductive particles
(Degussa, Lamp Black 101) with 5% by weight of Cu
An organic PTC composition was produced by kneading 60 parts by weight of the plated metal plated CB particles and 2 parts of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Geigy). This organic PTC composition was sandwiched between nickel-plated copper foils having a thickness of 35 μm, and thermocompression-bonded to 40 × 60 × total thickness of 1 mm by a hot press to produce an organic PTC element. Organic PT obtained
An overcurrent interruption experiment was performed with the C element interposed between the electrodes. FIG. 1 shows the relationship between the element resistance (R) and the peak current (Ip) when the overcurrent was interrupted. The room temperature resistance of this organic PTC element is 4 mΩ.
In the case of, the cut-off current Ip for 300 V and 50 kA was 6.5 kA.

Embodiment 3 FIG. 50 parts by weight of PE (Mitsubishi Chemical's JV070H) as an organic polymer and CB as conductive particles
(Lamp Black 101, Degussa) 60 parts by weight of metal-plated CB particles obtained by plating 5% by weight of Cu, and a phenolic antioxidant (Irganox 1, manufactured by Ciba-Geigy)
010) 2 parts were kneaded to produce an organic PTC composition.
This organic PTC composition was sandwiched between nickel-plated copper foils having a thickness of 35 μm, and thermocompression-bonded to 40 × 60 × total thickness of 1 mm by a hot press to produce an organic PTC element. An overcurrent cutoff experiment was performed with the obtained organic PTC element sandwiched between electrodes. This organic P
When the room temperature resistance of the TC element is 5 mΩ, 300 V, 50 k
The breaking current Ip for A was 6 kA.

Comparative Example 1 35 parts by weight of PE (manufactured by Mitsubishi Chemical, JV070H) as an organic polymer, 60 parts by weight of CB (manufactured by Degussa, Lamp Black 101) instead of metal-plated CB particles as conductive particles, and a phenolic antioxidant (manufactured by Ciba Geigy, 2 parts of Irganox 1010) were kneaded. This organic PTC composition was sandwiched between nickel-plated copper foils having a thickness of 35 μm, and was hot pressed to 40 × 60 × total thickness 1
mm. An overcurrent interruption experiment was performed with the obtained PTC element sandwiched between test electrodes. FIG. 1 shows the relationship between the element resistance (R) and the peak current (Ip) when the overcurrent was interrupted.
When the room temperature resistance of this PTC element is 3 mΩ, 300 V,
The breaking current for 50 kA showed 9 kA.

Comparative Example 2 As an organic polymer, PE (JV0
70H, Mitsubishi Chemical) 35 parts by weight, 60 parts by weight of CB particles and 3 parts by weight of Cu particles as conductive particles, and a phenolic antioxidant (Irganox 1010, Ciba-Geigy)
Two parts were kneaded. This PTC composition is sandwiched between nickel-plated copper foils having a thickness of 35 μm, and is hot pressed to 40 × 60 × total thickness 1
mm. The obtained laminate was sandwiched between electrodes. FIG. 1 shows the relationship between the element resistance (R) and the peak current (Ip) when the overcurrent is interrupted.
In the case of mΩ, the breaking current for 300 V and 50 kA is 9
kA was indicated.

[0021]

According to the first constitution of the organic PTC composition of the present invention, carbon black, whose surface is metal-plated and whose grape-like structure is maintained, is used as conductive particles. By being dispersed in a polymer, there is an effect that the resistivity at normal temperature is low, the resistance is low at the time of normal energization, the conductivity is good, and the peak current at the time of overcurrent interruption can be reduced. In addition, even under a large current and a high voltage, the metal is not melt-connected and a conductive circuit is not locally formed. Excellent PTC characteristics and current interruption performance,
There is an effect that an organic PTC composition having high safety and reliability can be obtained.

In the second structure of the organic PTC composition of the present invention, the first structure is characterized in that the amount of metal adhering to carbon black is set to 1 to 8% by weight.
It is possible to maintain good satisfactorily without impairing the tuft-like structure of grape B, and to maintain good electron conductivity. An adverse effect caused by attaching a metal is eliminated, and only a favorable effect can be expected. The effect of the first configuration becomes more remarkable.

[Brief description of the drawings]

FIG. 1 shows a relationship between a resistance of an organic PTC device according to an embodiment of the present invention and a peak current at the time of interrupting overcurrent according to a conventional organic PTC.
It is a figure shown with the thing of an element.

FIG. 2 is a diagram showing the relationship between the copper plating amount of CB and the resistivity of a PTC element according to the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tatsuya Hayashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Sadajiro Mori 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Rishi Electric Co., Ltd. (72) Inventor Shiro Murata 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanrishi Electric Co., Ltd. (72) Kenichi Nishina 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Inside (72) Inventor Manabu Sogabe 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Masahiro Ishikawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. In company

Claims (2)

[Claims] 1. An organic PTC composition obtained by dispersing carbon black, whose surface is metal-plated and having a grape tuft-like structure, as conductive particles in an organic polymer. 2. The organic PTC composition according to claim 1, wherein the amount of the metal attached to the carbon black is 1 to 8% by weight.