JP2003243204A - Organic positive temperature coefficient thermistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic positive temperature coefficient thermistor whose resistance at room temperature is low enough, resistance change between on and off operations is large enough, and stability of characteristics is excellent. <P>SOLUTION: The organic positive temperature coefficient thermistor with a constitution including conductive particles having spike-like projections whose surface is treated with at least a thermoplastic polymer and a coupling agent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a temperature sensor or an overcurrent protection element and has a PTC (positive temperature coefficient) whose resistance value increases as temperature rises.
organic positive temperature coefficient thermistor having a characteristic of resistivity.

[0002]

2. Description of the Related Art Organic positive temperature coefficient thermistors in which conductive particles are dispersed in a crystalline polymer are known in the art,
U.S. Pat. Nos. 3,243,753 and 3,351
No. 882 specification and the like. The increase in resistance is
It is considered that the crystalline polymer expands with melting and cuts the conductive path of the conductive fine particles.

The organic positive temperature coefficient thermistor can be used for a self-regulating heating element, an overcurrent protection element, a temperature sensor and the like. The characteristics required for these are that the room temperature resistance value during non-operation is sufficiently low, that the rate of change between the room temperature resistance value and the resistance value during operation is sufficiently large, and the change in resistance value due to repeated operation is small. To be

In order to satisfy such required characteristics, it has been proposed to incorporate a low molecular weight organic compound such as wax in a polymer matrix. Examples of such an organic positive temperature coefficient thermistor include polyisobutylene /
Paraffin wax / carbon black (F. Bueche, J.
Appl.Phys., 44 , 532, 1973), styrene-butadiene rubber / paraffin wax / carbon black system (F.Buech
e, J.Polymer Sci., 11 , 1319,1973), low density polyethylene / paraffin wax / carbon black system (K.Ohe et al.
al., Jpn.J.Appl.Phys., 10 , 99, 1971). Further, Japanese Patent Publication No. 62-16523, Japanese Patent Publication No. 7-109786, No. 7-48396, JP-A Nos. 62-51184, 62-51185, 62-51186, 62-511.
87, JP-A 1-231284, 3-132001, 9-27383
No. 9-69410 discloses a self-temperature control heating element using an organic positive temperature coefficient thermistor using a low molecular weight organic compound, a current limiting element, and the like. In these cases, it is considered that the resistance value increases due to the melting of the low molecular weight organic compound.

Therefore, the advantage of using a low-molecular weight organic compound is that the crystallinity is generally higher than that of a polymer, so that the rise when the resistance increases due to temperature rise becomes sharp. Further, by using low molecular weight organic compounds having different melting points, the temperature at which the resistance increases (operating temperature) can be easily controlled.

Further, since a polymer is likely to be in a supercooled state, the temperature at which the resistance value returns when the temperature is lowered is lower than the operating temperature when the temperature is raised, but a hysteresis is obtained by using a low molecular weight organic compound. Can be suppressed. In the case of a crystalline polymer, the melting point and the operating temperature can be changed by the difference in the molecular weight and the degree of crystallinity, and by copolymerizing with a comonomer, but at that time, the crystalline state is changed, so that the sufficient PTC is obtained. The characteristics may not be obtained. This tends to be more remarkable when the operating temperature is set to 100 ° C. or lower.

In the above-mentioned prior art, carbon black or graphite is mainly used as the conductive particles, and there is no example in which a low room temperature resistance and a large resistance change rate are compatible with each other. Among the above-mentioned prior art, Jpn.J.Appl.Phys., Vol 10 , p99, 1971
Discloses an example in which the specific resistance value is increased by 10 ⁸ Ωcm. However, the specific resistance at room temperature is as high as 10 ⁴ Ωcm, which is not practical for use as an overcurrent protection device or a temperature sensor. In other prior arts, the increase in resistance is from 10 ¹ Ω or less to about 10 ⁴ Ω, and the room temperature resistance is not sufficiently low.

The inventors of the present invention have found that by using conductive particles having spike-like protrusions, both low room temperature resistance and a large rate of change in resistance can be achieved at the same time. JP-A-10-214705 (JP-A-11-168005) Is proposed in.
The operating temperature is 100 ° C. or less, the room temperature specific resistance is 0.08 Ωcm or less, and the resistance change rate is 11 digits or more.

In addition, Japanese Unexamined Patent Publication (Kokai) No. 5-47503 (Patent No. 3022644) discloses an organic positive temperature coefficient thermistor obtained by kneading a crystalline polymer and conductive particles having spike-shaped projections. ing. US Patent 5
No. 378407 discloses a conductive polymer composition composed of filamentary Ni having spike-like protrusions and a crystalline polyolefin, an olefin-based copolymer, or a fluoropolymer. There is no teaching to use certain low molecular weight organic compounds.

A PTC composition obtained by subjecting a conductive composition of an organic positive temperature coefficient thermistor to a surface treatment is disclosed in JP-A-10-3.
03003, JP-A-10-116702,
JP-A-2000-331803, JP-A-2000-1
No. 618 and Japanese Patent Laid-Open No. 2001-167905. None of these prior arts describes the use of conductive particles having spike-like protrusions, nor the use of low molecular weight organic compounds. Furthermore, in Japanese Patent Laid-Open No. 2000-331803, a PTC that is stable and has good reproducibility against repeated use.
A composition is proposed, but its initial room temperature resistivity is 1Ω
cm, and does not hold low resistance. Further, the method of treating the surface of the conductive particles with the coupling agent is not mentioned in detail, and the initial resistance value and resistance change rate are also unknown.

The inventors of the present invention have proposed an organic positive temperature coefficient thermistor in which a crosslinking treatment is carried out using a silane coupling agent in Japanese Patent Application No. 11-20599 (JP-A 2000-82602). In this product, a silane coupling agent is applied to the entire mixture for the purpose of cross-linking to improve the stability of the characteristics. That is, it is said that the organic material has a three-dimensional network cross-linking structure by the coupling agent to improve the characteristic stability. In addition, since the whole mixture is treated, a chemical bond is also generated between the organic material and the inorganic material via the coupling agent, and it is also effective in strengthening the organic material-inorganic material interface.

However, the treatment of the coupling agent in this prior art is for the purpose of crosslinking, and the surface treatment of the conductive particles is not performed. Therefore, the effect of modifying the interface between the inorganic and organic materials is incomplete. Further, this is not intended to improve the dispersibility of the conductive particles. Therefore, the finer the conductive particles are, the greater the cohesiveness thereof becomes, and it becomes difficult to ensure both low room temperature resistance and high resistance change rate and characteristic stability.

[0013]

An object of the present invention is to use conductive particles having surface-treated spike-like protrusions as a conductive composition, which is superior to conventional organic positive temperature coefficient thermistors. An object is to provide an organic positive temperature coefficient thermistor having excellent property stability.

[0014]

That is, the above object is achieved by the following constitution of the present invention. (1) An organic positive temperature coefficient thermistor containing at least a thermoplastic polymer and conductive particles having spike-like protrusions which are surface-treated with a coupling agent. (2) The organic positive temperature coefficient thermistor according to claim 1, wherein the coupling agent is added in an amount of at least 0.1 to 20 mass% with respect to the conductive particles. (3) The organic positive temperature coefficient thermistor according to (1) or (2) above, wherein the coupling agent is a silane coupling agent. (4) The organic positive temperature coefficient thermistor according to any one of the above (1) to (3), wherein the conductive particles having the spike-like protrusions are connected in a chain. (5) The organic positive temperature coefficient thermistor according to any one of the above (1) to (4), wherein the thermoplastic polymer is a polymer polymerized by using a metallocene catalyst. (6) The above (1) containing a low molecular weight compound
An organic positive temperature coefficient thermistor according to any one of (5).

[0015]

The organic positive temperature coefficient thermistor of the present invention is characterized by having a thermoplastic polymer, preferably a low molecular weight organic compound, and surface-treated conductive particles having spike-like projections.

In the present invention, since spike-shaped conductive particles are used, tunnel current is more likely to flow due to the shape, and the room temperature resistance can be kept lower than that of spherical conductive particles. Further, since the distance between the conductive particles is larger than that of the spherical conductive particles, the resistance change can be increased.

Further, by using the surface-treated conductive particles, it is possible to suppress the oxidative deterioration of the surface of the conductive particles, and the surface of the conductive particles is modified by the surface treatment to form a matrix with the organic substance matrix. The interface is strengthened, and the dispersibility of the conductive particles in the organic matrix is improved,
It is possible to improve reliability test characteristics such as high temperature and high humidity and thermal shock, and to improve intermittent load test characteristics.

As the thermoplastic polymer used in the present invention, a crystalline polymer polymerized by using a metallocene catalyst may be used, and temperature characteristics with small hysteresis can be obtained at the time of temperature rise and the temperature decrease.

The present inventors have already filed Japanese Patent Application No. 11-20.
No. 599 (Japanese Patent Laid-Open No. 2000-82602) proposes to perform a crosslinking treatment using a silane coupling agent. However, this is intended to improve the property stability by performing a crosslinking treatment, and the surface treatment of the conductive particles strengthens the organic material-conductive particle interface and improves the dispersibility of the conductive particles. Is not intended for. Therefore, the finer the conductive particles are, the greater the cohesiveness thereof becomes, and it becomes difficult to secure the characteristic stability. For example, when fine conductive particles are used according to this prior art, the room temperature resistance value of the obtained device has large variations. However, according to the present invention, it is possible to obtain a stable element with less variation.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The organic positive temperature coefficient thermistor of the present invention is characterized by containing a thermoplastic polymer, preferably a low molecular weight organic compound, and conductive particles having surface-treated spike-like protrusions.

As the thermoplastic polymer matrix, polyolefin (eg polyethylene), olefin copolymer (eg ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer), halogen polymer, polyamide, polystyrene, polyacrylonitrile, polyethylene oxide, polyacetal. , Thermoplastic modified cellulose, polysulfones, thermoplastic polyesters (PET, etc.), polyethyl acrylate, polymethyl methacrylate, etc.

Specifically, high density polyethylene [for example, trade name HiZex 2100JP (manufactured by Mitsui Petrochemicals), trade name Marlex 6003 (manufactured by Philips), trade name HY540 (manufactured by Nippon Polychem), low density polyethylene [for example , Trade name LC500 (manufactured by Nippon Polychem), trade name DYNH-1 (manufactured by Union Carbide Co., Ltd.)], medium density polyethylene [for example, trade name 260
4M (manufactured by Gulf Co., etc.), ethylene-ethyl acrylate copolymer [for example, trade name DPD6169 (manufactured by Union Carbide Co.)], ethylene-vinyl acetate copolymer [for example, trade name LV241 (manufactured by Nippon Polychem).
Etc.], ethylene-acrylic acid copolymer [for example, trade name EAA455 (manufactured by Dow Chemical Co., Ltd.)], ionomer [for example, trade name Himilan 1555 (manufactured by Mitsui DuPont Polychemical Co., Ltd.)], polyvinylidene fluoride [for example, trade name The name Kynar461 (manufactured by Elf Atchem) and the like], vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer [for example, the product name KynarADS (manufactured by Elf Atchem), etc.] and the like.

Of these, polyolefin is preferred, and polyethylene is particularly preferred. High-density, linear low-density, and low-density polyethylene grades can be used, but high-density and linear low-density polyethylene are preferred. Its melt viscosity (MFR) is 15.0 g /
It is preferably 10 min or less, particularly preferably 8.0 g / 10 min or less.

The polymer used in the present invention is preferably one synthesized using a metallocene catalyst, that is, a catalyst containing an organometallic compound metallocene as a main component. The metallocene catalyst in the present invention is a kind of sandwich compound,
A bis (cyclopentadienyl) metal complex-based catalyst.

Such a metallocene catalyst is usually a metallocene catalyst component (a) consisting of a transition metal compound of Group IVB, VB or VIB of the Periodic Table having, for example, at least one ligand having a cyclopentadienyl skeleton. ), An organoaluminum oxy compound catalyst component (b), a particulate carrier (c), and optionally an organoaluminum compound catalyst component (d), an ionized ionic compound catalyst component (e).
Formed from.

The metallocene catalyst component (a) preferably used in the present invention has at least one ligand having a cyclopentadienyl skeleton, and is represented by IVB and V of the periodic table.
There are transition metal compounds of Group B and VIB. Examples of such transition metal compounds include transition metal compounds represented by the following general formula [I].

ML1 _x ... [I] In the formula, x is the valence of the transition metal atom M. M is preferably a transition metal atom selected from Group IVB of the periodic table, specifically zirconium, titanium or hafnium. Of these, zirconium and titanium are preferable.

L1 is a ligand that coordinates to the transition metal atom M, and at least one of them is a ligand L1.
Is a ligand having a cyclopentadienyl skeleton.
Specific examples of the ligand L1 having a cyclopentadienyl skeleton coordinated to the transition metal atom M include:
Examples thereof include an alkyl-substituted cyclopentadienyl group such as a cyclopentadienyl group, an indenyl group, a 4,5,6,7-tetrahydroindenyl group, and a fluorenyl group.
These groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

When the compound represented by the above general formula [I] contains two or more groups having a cyclopentadienyl skeleton, the groups having two cyclopentadienyl skeletons among them are ethylene, propylene and the like. An alkylene group of
It may be bonded via a silylene group or a substituted silylene group such as a dimethylsilylene group, a diphenylsilylene group, a methylphenylsilylene group and the like.

As the organoaluminum oxy compound catalyst component (b), aluminoxane is preferably used. Specifically, the repeating unit represented by the formula: -Al (R) O- [wherein R is an alkyl group] is usually about 3 to 50 methylaluminoxane, ethylaluminoxane, methylethylaluminoxane. Etc. are used. In addition to a chain compound, a cyclic compound can be used.

The fine particle carrier (c) used in the preparation of the olefin polymerization catalyst is an inorganic or organic compound having a particle size of usually about 10 to 300 μm, preferably 20 to 200 μm. It is a solid.

The inorganic carrier is preferably a porous oxide, specifically, SiO ₂ , Al ₂ O ₃ , MgO, ZrO.
₂ , TiO _{2 and the} like can be exemplified. Specific examples of the organoaluminum compound catalyst component (d) used in the preparation of the olefin polymerization catalyst include trialkylaluminum such as trimethylaluminum, dialkylaluminum halides such as dimethylaluminum chloride, and methylaluminum sesquichloride. And other alkylaluminum sesquihalides and the like.

As the ionizable ionic compound catalyst component (e), for example, triphenylboron, MgCl ₂ , Al ₂ O ₃ described in USP-5,321,106 are disclosed.
Lewis acids such as SiO ₂ —Al ₂ O ₃ ; ionic compounds such as triphenylcarbenium tetrakis (pentafluorophenyl) borate; carborane compounds such as dodecaborane and bis n-butylammonium (1-carbedodeca) borate. .

The polymer used in the present invention can be obtained by polymerizing the raw materials under various conditions in the gas phase or in the liquid phase in the form of slurry or solution in the presence of the above catalyst.

As such a polymer, an ethylene polymer (a homopolymer of ethylene, ethylene and 4 to 4 carbon atoms) is used.
There are about 20 copolymers of α-olefin and cyclic olefin, homopolymers of propylene, copolymers of propylene and α-olefin, etc.) and styrene polymers. Among them, ethylene-based polymers are preferable, and linear low-density polyethylene (LLDPE) which is a copolymer of ethylene and α-olefin is preferable.

The linear low-density polyethylene is preferably obtained by copolymerizing ethylene with an α-olefin having 4 to 20 carbon atoms.

Specific examples of the α-olefin having 4 to 20 carbon atoms used for copolymerization with ethylene include propylene, 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene. , 1-octene, 1-decene, 1-dodecene and the like. Among these, the number of carbon atoms is 4 to 10
Α-olefins of, especially C 4-8 α-olefins are preferred.

The α-olefin as described above is
Alternatively, two or more kinds can be used in combination. The linear low-density polyethylene used in the present invention has a structural unit derived from ethylene of 50% by mass or more and less than 100% by mass, preferably 75 to 99% by mass, more preferably 8% by mass.
It is present in an amount of 0 to 95% by mass, particularly preferably 85 to 95% by mass, and a structural unit derived from an α-olefin having 3 to 20 carbon atoms is 50% by mass or less, preferably 1 to 25%.
It is desirable to be present in an amount of% by weight, more preferably 5 to 20% by weight and particularly preferably 5 to 15% by weight.

The linear low density polyethylene used in the present invention preferably has a density of 0.900 to 0.940 g /
cm ³ , more preferably 0.910 to 0.930 g / cm ³
Is in the range.

The linear low density polyethylene melt flow rate (MFR; ASTM D1238, 190 ° C., load)
2.16 kg) is preferably in the range of 0.05 to 20 g / 10 minutes, more preferably 0.1 to 10 g / 10 minutes.

The linear low-density polyethylene used in the present invention preferably has a narrow molecular weight distribution as described above, and Mw / Mn, which is a measure of the molecular weight distribution, is 6 or less, more preferably 4 or less. Mw is the weight average molecular weight, M
n is a number average molecular weight, and is measured by a gel permeation chromatography (GPC) method.

The number of long-chain branches of the linear low-density polyethylene used in the present invention is 5 with respect to the number of carbon atoms in the main chain.
/ 1000 carbons or less, more preferably 1/1000 carbons or less. The number of long chain branches is measured by ¹³ C-NMR method.

In the present invention, it is preferable to use a low molecular weight organic compound. In a normal organic PTC thermistor, the element operates (the resistance value increases) due to the expansion of the polymer organic matrix. An advantage of using a low-molecular weight organic compound as an operating substance is that it generally has a higher degree of crystallinity than a polymer, and therefore the rise when the resistance value increases due to temperature rise becomes sharp. Further, by using low molecular weight organic compounds having different melting points, the temperature at which the resistance increases (operating temperature) can be easily controlled. Furthermore, since the polymer easily takes a supercooled state, the temperature at which the resistance value recovers when the temperature is lowered is lower than the operating temperature when the temperature is raised, but this is suppressed by using a low molecular weight organic compound. be able to. In the case of a crystalline polymer, the melting point and the operating temperature can be changed by the difference in the molecular weight and the degree of crystallinity, and by copolymerization with a comonomer, but at that time, the crystal state changes, which is sufficient. The PTC characteristics may not be obtained in some cases. This tends to be more remarkable when the operating temperature is set to 100 ° C. or lower.

The low molecular weight organic compound used in the present invention has a molecular weight of up to about 2000, preferably up to about 1,000.
More preferably, it is not particularly limited as long as it is a crystalline substance of 200 to 800, but a substance which is solid at room temperature (a temperature of about 25 ° C.) is preferable.

Since the object of the present invention is to obtain an organic positive temperature coefficient thermistor having an operating temperature of 200 ° C. or lower, preferably 100 ° C. or lower, the low molecular weight organic compound has a melting point of 4%.
It is desirable that the temperature is 0 to 200 ° C, preferably 40 to 100 ° C.

Specifically, waxes (specifically, petroleum waxes such as paraffin wax and microcrystalline wax, natural waxes such as plant waxes, animal waxes and mineral waxes), fats and oils (specifically Include those referred to as fats or solid fats). The components of wax and fats and oils include hydrocarbons (specifically, alkane-based straight chain hydrocarbons having 22 or more carbon atoms) and fatty acids (specifically, alkane-based straight chain hydrocarbons having 12 or more carbon atoms). Fatty acid, etc., fatty acid ester (specifically, having 2 carbon atoms)
Methyl ester of saturated fatty acid obtained from 0 or more saturated fatty acid and lower alcohol such as methyl alcohol),
Fatty acid amides (specifically, unsaturated fatty acid amides such as oleic acid amide and erucic acid amide), aliphatic amines (specifically, aliphatic primary amines having 16 or more carbon atoms),
Higher alcohols (specifically, n-alkyl alcohols having 16 or more carbon atoms), chlorinated paraffins and the like can be used alone or in combination as low molecular weight organic compounds. The low molecular weight organic compound may be appropriately selected in consideration of the polarity of the polymer matrix in order to improve the dispersion of each component. Petroleum wax is preferred as the low molecular weight organic compound.

These low molecular weight organic compounds are commercially available, and commercially available products can be used as they are.

In the present invention, as the low molecular weight organic compound,
Melting point mp is 40 to 200 ° C., more preferably 40 to 1
It is preferable to use one having a temperature of 00 ° C. Examples thereof include paraffin wax (for example, tetracosan C ₂₄ H ₅₀ ; mp 49 to 52 ° C., hexatriacontane C ₃₆ H ₇₄ ; mp 73 ° C., trade name HNP-10 (manufactured by Nippon Seiro Co., Ltd.); mp 75 ° C., HNP-3 (manufactured by Nippon Seiro Co., Ltd.);
mp66 ° C.), microcrystalline wax (for example, trade name Hi-Mic-1080 (manufactured by Nippon Seiro Co., Ltd.); mp83 ° C., Hi-Mic-1045 (manufactured by Nippon Seiro Co., Ltd.); mp70 ° C., Hi-Mic2045 (Japan). Seiwa Co., Ltd .; mp 64 ° C., Hi-Mic 3090 (Nippon Seiwa Co., Ltd.); mp 89 ° C., Serrata 104 (Nippon Petroleum Refining Co., Ltd.); ), Fatty acids (for example, behenic acid (manufactured by Nippon Seika); mp81 ° C, stearic acid (manufactured by Nippon Seika); mp72 ° C, palmitic acid (manufactured by Nippon Seika);
mp64 ° C, etc.), fatty acid ester (for example, arachidic acid methyl ester (manufactured by Tokyo Kasei); mp48 ° C, etc.),
There are fatty acid amides (for example, oleic acid amide (Nippon Seika); mp 76 ° C.). Further, polyethylene wax (for example, trade name Mitsui High Wax 110 (manufactured by Mitsui Petrochemical Industry Co., Ltd .; mp100 ° C.), stearic acid amide (mp109 ° C.), behenic acid amide (mp111).
C), N-N'-ethylenebislauric acid amide (mp
157 ° C), N-N'-dioleyl adipamide (mp119 ° C), N-N'-hexamethylenebis-1.
There is also 2-hydroxystearic acid amide (mp 140 ° C.) and the like. Further, a compounded wax in which resins are mixed with paraffin wax, and a microcrystalline wax is mixed with this compounded wax and has a melting point of 40 to 20.
Those at 0 ° C. can also be preferably used.

The low molecular weight organic compounds may be used alone or in combination of two or more depending on the operating temperature and the like.
In order to improve the dispersibility of each component, it may be appropriately selected in consideration of the polarity of the thermoplastic polymer.

The content of the low molecular weight organic compound is 0.05 to 4 of the total mass of the polymer matrix (including the curing agent etc.).
It is preferably double, particularly 0.1 to 2.5 times. If this mixing ratio becomes small and the content of the low molecular weight organic compound becomes small, it becomes difficult to obtain a sufficient resistance change rate.
On the contrary, when the mixing ratio becomes large and the content of the low molecular weight compound increases, the element body is largely deformed when the low molecular weight compound melts, and it becomes difficult to mix with the conductive particles.

In the organic positive temperature coefficient thermistor of the present invention, endothermic peaks are observed in the vicinity of the melting point of the polymer matrix used and in the vicinity of the melting point of the low molecular weight organic compound by differential scanning calorimetry (DSC). This is considered to have a sea-island structure in which the polymer matrix and the low-molecular weight organic compound are independently dispersed.

As the conductive metal particles, copper, aluminum, nickel, tungsten, molybdenum, silver, zinc,
Cobalt or the like is used, but nickel and copper are preferable.

As the shape, a spherical shape, a flake shape, a rod shape or the like is used. Particularly preferably used is one having spike-like protrusions on the surface. It is considered that the tunnel current easily flows due to the surface shape, and the room temperature resistance can be reduced more than that of the spherical conductive metal particles having no protrusion.

Since the distance between the conductive metal particles is larger than that of the spherical particles, the rate of change in resistance can be increased.

The conductive particles having spike-like projections used in the present invention are formed of primary particles each having sharp projections and have a height of 1/3 to 1/50 of the particle diameter. There are multiple cone-shaped spike-shaped protrusions of one particle (usually 1
0 to 500) exist. The material is metal,
Ni or the like is particularly preferable.

Such electrically conductive particles may be powders in which one particle is present and one particle is individually present.
It is preferable that about 1000 particles are connected in a chain to form secondary particles. Some of the chain-like particles may have primary particles. An example of the former is a spherical nickel powder having spike-shaped protrusions, which has a trade name of INCO Type.
e 123 Nickel powder (manufactured by Inco), having an average particle size of about ³ to 7 μm, an apparent density of about 1.8 to 2.7 g / cm ³ , and a specific surface area of 0.34.
It is about 0.44 m ² / g.

The latter example, which is preferably used, is a filamentary nickel powder, which has a trade name of IN.
It is commercially available as CO Type 210, 255, 270, 287 Nickel Powder (manufactured by Inco), and among these, INCO Type 210, 255 is preferable.
The average particle size of the primary particles is preferably 0.1
It is not less than μm, more preferably not less than 0.2 μm and not more than 4.0 μm. Of these, the average particle size of the primary particles is most preferably 0.5 μm or more and 3.0 μm or less, and 50% by mass or less of particles having an average particle size of 0.1 μm or more and less than 0.4 μm may be mixed therein. Also, the apparent density is 0.3
~ 1.0 g / cm ³ , specific surface area 0.4 ~ ^2.5 m ² /
It is about g.

The average particle diameter in this case is measured by the Fisher subsieve method.

Such conductive particles are described in JP-A-5-47503 and US Pat. No. 5,378,407.

In addition to the conductive particles having spike-like protrusions, carbon black, graphite, carbon fiber, conductive particles for auxiliary conductivity are also used.
Metal-coated carbon black, graphitized carbon black, carbon-based conductive particles such as metal-coated carbon fibers, spherical, flake-shaped, fibrous, etc. metal, different metal-coated metal (silver-coated nickel, etc.) particles, tungsten carbide, nitriding Ceramic-based conductive particles of titanium, zirconium nitride, titanium carbide, titanium boride, molybdenum silicide, etc., and conductive potassium titanate whiskers described in JP-A Nos. 8-31554 and 9-27383. May be added. Such conductive particles are preferably 25% by mass or less of the conductive particles having spike-shaped protrusions.

The content of the conductive particles is such that the thermoplastic polymer,
When the total amount of the low molecular weight organic compound and the conductive particles is 100% by volume, the compounding amount of the conductive particles is preferably 25 to 50% by volume. If the mixing ratio becomes small and the content of the conductive particles becomes small, the room temperature resistance during non-operation cannot be sufficiently lowered. On the other hand, when the content of the conductive particles increases, it becomes difficult to obtain a large resistance change rate, and it becomes difficult to uniformly mix the particles, and it becomes difficult to obtain stable characteristics.

The conductive particles are surface-treated with a coupling agent. By performing the surface treatment with the coupling agent, the compatibility with the matrix resin is improved and the dispersibility is remarkably improved. Therefore, variations in characteristics between products can be suppressed, the content of the conductive particles can be increased, and the room temperature resistance during non-operation can be sufficiently reduced. Moreover, handling properties can be improved by reducing the bulk of the conductive particles. Also,
It also has the effect of suppressing the oxidation of the conductive particles, improving the storage stability, and improving the thermal shock resistance.

The effect of such a surface treatment is particularly effective for conductive particles having a small particle diameter, and in the case of the above filamentary nickel powder, the average primary particle diameter is 0.1 to 0.1.
It is effective in the range of 3 μm.

The surface treatment of the electrically conductive particles is carried out by mixing the electrically conductive particles with a solution of the treating agent dissolved in a solvent to form a slurry, or by spraying the electrically conductive particles with the agent dissolved in the solvent. Either of the dry methods of post-drying may be used.

As the surface treatment coupling agent, it is preferable to use a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, or the like, and more preferable to use a silane coupling agent. Good. The amount of the coupling agent added is 0.
It is preferable to add about 1 to 20% by mass, more preferably about 0.5 to 10% by mass. The coupling agent can be condensed by dealcoholation and dehydration, and has an alkoxy group capable of chemically bonding with an inorganic oxide and a functional group having an affinity with an organic material.

The alkoxy group preferably has a small number of carbon atoms, and a methoxy group and an ethoxy group are particularly preferable. The functional group having an affinity with the organic material is preferably a hydrocarbon group, and C =
It may contain a C double bond.

The silane coupling agent is preferably liquid at room temperature. Specifically, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, methyltrimethoxysilane,
Methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, octadecyltri Methoxysilane, hexadecyltrimethoxysilane, γ- (meth)
Acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ-
Examples thereof include (meth) acryloxypropylmethyldimethoxysilane and γ- (meth) acryloxypropylmethyldiethoxysilane. Among these, vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and the like are particularly preferable. As the molecular weight of the coupling agent increases, the reactivity with the substrate tends to decrease.

In addition, titanate coupling agents and aluminum coupling agents can also be used. Examples of the titanate-based coupling agent include monocoxyl type such as isopropyl triisostearoyl titanate, isopropyl trioctanoy titanate, isopropyl diisostearoyl cumylphenyl titanate, isopropyl distearoyl methacryl titanate, and isopropyl tri (dioctyl pyrophosphate) titanate. Alternatively, tetraisopropylpyrudi (dilauryl phosphite) titanate, isostearoyl oxyacetate, isostearoyl acryloxy acetate, distearoyl ethylene titanate, dimethacryl ethylene titanate and the like can be mentioned. Further, as the aluminum-based coupling agent, it is possible to use all those which are effective in improving the adhesiveness between the metal and the plastic, such as acetoalkoxy aluminum diisopropylate.

The coupling agent is usually bonded as a single molecule so as to cover the surface of the conductive particles, but there are cases where a plurality of molecules are bonded due to condensation of the coupling agents. . The coverage is preferably 5 to 1
It is about 000%. Here, the coverage is derived by the following formula. Coverage (%) = [Minimum coating area of coupling agent (m ² /
g) × amount of coupling agent fixed (g)] / [specific surface area of conductive particles (m ² / g) × conductive particle filling amount (g)] × 100

Here, the minimum coating area of the coupling agent means the minimum area that can be coated with the coupling agent, assuming that the surface of the conductive particles is monomolecularly treated with the coupling agent. That is. This minimum covered area is unique to each type of coupling agent, and its value is usually described in the characteristic value table of the catalog. The amount of the coupling agent adhered is the amount of the coupling agent adhered to the conductive particles treated with the coupling agent and can be confirmed by fluorescent X-ray analysis or the like.

Next, a method of manufacturing the organic positive temperature coefficient thermistor of the present invention will be described.

First, a predetermined amount of polymer, if necessary, a low molecular weight organic compound and conductive particles having spike-like protrusions are kneaded and dispersed. At this time, the conductive particles of the present invention have been surface-treated in advance with a coupling agent, so that kneading with a polymer or the like and dispersibility are extremely good, and uniform dispersion can be obtained.

Mixing / dispersion may be carried out by a known method, and the temperature is not lower than the melting point of the polymer used, preferably 5 to 40 ° C.
The kneading may be carried out at a high temperature for about 5 to 90 minutes with a mill or the like. When a low molecular weight organic compound is used, the polymer and the low molecular weight organic compound may be melt-mixed in advance, or may be dissolved and mixed in a solvent. Various stirrers, dispersers,
A mill, a paint roll machine, or the like is used. If air bubbles are mixed in during mixing, vacuum degassing is performed. For viscosity adjustment,
Various solvents such as aromatic hydrocarbons, ketones and alcohols may be used.

The obtained kneaded product may be subjected to a crosslinking treatment if necessary. Specifically, chemical crosslinking using an organic peroxide, crosslinking by irradiation with radiation, or a silane crosslinking method using a condensation reaction of silanol groups in the presence of water by grafting a silane coupling agent can be used.

An antioxidant may be mixed in order to prevent thermal deterioration of the high molecular weight polymer and the low molecular weight organic compound, and phenols, organic sulfurs, phosphites and the like are used.

The kneaded product is press-formed into a sheet having a predetermined thickness, and a metal electrode such as Ni or Cu is thermocompression-bonded or a conductive paste or the like is applied to form an electrode.

The sheet molded body thus obtained is punched into a desired shape to form a thermistor element.

Further, as a good thermal conductive additive, Japanese Patent Laid-Open No.
7-12061, silicon nitride, silica, alumina, clay (mica, talc, etc.), Japanese Patent Publication No. 7-
Silicon, silicon carbide, silicon nitride, beryllia, selenium described in Japanese Patent No. 77161, JP-A-5-217
Inorganic nitrides, magnesium oxide and the like described in Japanese Patent No. 711 may be added.

To improve durability, Japanese Patent Laid-Open No. 5-2261
Titanium oxide, iron oxide, zinc oxide, silica, magnesium oxide, alumina, chromium oxide, barium sulfate, calcium carbonate, calcium hydroxide, lead oxide described in JP-A-6-68963. Inorganic solid having a high relative dielectric constant, specifically, barium titanate, strontium titanate, potassium niobate or the like may be added.

To improve the withstand voltage, Japanese Patent Laid-Open No. 7438/1992.
Boron carbide and the like described in Japanese Patent Publication No. 3 may be added.

In order to improve the strength, JP-A-5-74603 is used.
The hydrated alkali titanate described in JP-A-8-17563 and the titanium oxide, iron oxide, zinc oxide, silica and the like described in JP-A-8-17563 may be added.

As a crystal nucleating agent, JP-B-59-10553
Alkali halide, melamine resin described in JP-A-6-76511, benzoic acid, dibenzylidene sorbitol, metal benzoate described in JP-A-6-76511, and JP-A-7-6864. Talc, zeolite, dibenzylidene sorbitol, sorbitol derivative (gelling agent) described in JP-A-7-263127, asphalt, and bis (4-t-butylphenyl) sodium phosphate are added. Good.

As an arc control agent, Japanese Patent Publication No. 4-2
Alumina, magnesia hydrate described in Japanese Patent No. 8744, metal hydrate described in JP-A No. 61-250058, silicon carbide and the like may be added.

As a metal damage inhibitor, JP-A-7-6864 is known.
Irganox MD1024 described in Japanese Patent Publication No.
(Manufactured by Ciba Geigy) or the like may be added.

Further, as a flame retardant, JP-A-61-239
Diantimony trioxide and aluminum hydroxide described in Japanese Patent No. 581, magnesium hydroxide described in JP-A-5-74603, and further 2,2-bis (4-hydroxy-3,5-). Organic compounds (including polymers) containing halogen such as dibromophenyl) propane and polyvinylidene fluoride (PVDF), phosphorus-based compounds such as ammonium phosphate and the like may be added.

In addition to these, zinc sulfide, basic magnesium carbonate, aluminum oxide, calcium silicate, magnesium silicate, aluminosilicate clay (mica, talc, kaolinite, montmorillonite, etc.), glass powder, glass flakes, glass fiber , Calcium sulfate, etc. may be added.

These additives include a polymer matrix,
It is preferably 25% by mass or less of the total mass of the low molecular weight organic compound and the conductive particles.

The organic positive temperature coefficient thermistor of the present invention has a low initial resistance when it is not operating, and its room temperature specific resistance value is 10%.
It is about ^-4 to 10 ^-2 Ω · cm, the rise of resistance during operation is steep, and the rate of resistance change from non-operation to operation is as large as 6 digits or more.

FIG. 1 shows a structural example of the organic positive temperature coefficient thermistor of the present invention. The organic positive temperature coefficient thermistor of the present invention comprises a thermistor element body 2 having at least a thermoplastic polymer matrix, a low molecular weight organic compound and surface-treated conductive particles, and a pair of thermistor element bodies 2 sandwiching the thermistor element body 2. Electrode 3 is arranged. The illustrated example shows an example of the sectional shape of the thermistor, and various modifications can be made without departing from the spirit of the present invention. Also,
The plane shape may be a circle, a quadrangle, or other optimum shape depending on the required characteristics and specifications.

[0090]

[Example 1] As a thermoplastic polymer, a linear low density polyethylene synthesized by a gas phase method using a metallocene catalyst (manufactured by Mitsui Chemicals, trade name Evolue sp2520,
MFR = 1.7 g / 10 min, melting point: 121 ° C., paraffin wax (Baker Petrolit) as a low molecular weight organic compound
e company, trade name Poly Wax655, melting point 99 ° C), filamentary nickel powder as conductive particles (INCO, trade name Type 210 nickel powder, average particle size 0.5)
～1.0Myuemu, apparent density to 0.8 / cm ^3, was used a specific surface area 1.5~2.5m ² / g).

The nickel powder, which is a conductive particle, was surface-treated with a silane coupling agent as follows.
1% by mass of acetic acid in a mixed solution of 65 g of water and 65 g of ethanol
Vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name KBE10) as a silane coupling agent.
03) 0.5 mass% was added to prepare a silane coupling agent solution. 100 g of nickel powder was mixed with this silane coupling agent solution to form a uniform slurry, which was stirred, filtered and dried.

45% by volume of linear low-density polyethylene, 25% by volume of paraffin wax, and 30% by volume of surface-treated nickel powder were kneaded in a mill at 150 ° C. for 30 minutes.

The kneaded product was formed into a sheet having a thickness of 0.7 mm by a hot press machine at 150 ° C., and both sides were sandwiched by Ni foil electrodes having a thickness of about 30 μm. Was crimped to a total thickness of 0.4 mm. After irradiating this with an electron beam to perform crosslinking, it was punched out into a shape of 3.6 mm × 9.0 mm to obtain an organic positive temperature coefficient thermistor element.

This device was heated from room temperature to 120 ° C in a constant temperature bath.
By heating and cooling at 2 ° C / min at 4 ° C with a predetermined temperature
The resistance value was measured to obtain a temperature-resistance curve. Initial room
Temperature resistance is 5.0 × 10^-Four Ω (4.1 x 10^-3 Ωcm),
The resistance increases rapidly around 90 ° C, and the resistance change rate is about 7 digits.
The high rate of resistance change despite low room temperature resistance
It was confirmed that After being cooled to room temperature
Resistance value is 5.0 × 10 ^-Four Ω (4.1 x 10^-3 Ωcm) and
There is no change from the room temperature resistance value before heating, and the resettability of the resistance value is good.
It was good.

Further, the variation in the initial room temperature resistance value is small, and 9 out of 10 elements are measured, 5.0 × 10 ⁻⁴ Ω.
(4.1 × 10 ⁻³ Ωcm), 1 piece is 1 × 10 ⁻³ Ω (8.
1 × 10 ⁻³ Ωcm).

About this element, -40 ° C for 30 minutes, 85
A thermal shock test was carried out with one cycle of 30 minutes at ℃. After repeating this for 200 cycles, the room temperature resistance was 9.0.
The change was small at × 10 ^-3 Ω (7.3 × 10 ^-2 Ωcm).

[Example 2] Linear low-density polyethylene 5
An organic positive temperature coefficient thermistor was prepared by performing the same operation as in Example 1 except that 7% by volume, 8% by volume of paraffin wax and 35% by volume of surface-treated nickel powder were used.

When measurement was carried out in the same manner as in Example 1 to obtain a resistance-temperature curve, the initial room temperature resistance value was 5.0 ×.
A characteristic of 10 ⁻⁴ Ω (4.1 × 10 ⁻³ Ωcm) and a resistance change rate of 6 digits was obtained, and the resistance value after cooling to room temperature was
The change was slight at 1.0 × 10 ⁻³ Ω (8.1 × 10 ⁻³ Ωcm).

The initial room temperature resistance value was 8 during measurement of 10 devices.
The number is 5.0 × 10 ⁻⁴ Ω (4.1 × 10 ⁻³ Ωcm), the number is 8.0 × 10 ⁻⁴ Ω (6.5 × 10 ⁻³ Ωcm),
The variation was small.

[0100] room temperature resistance after the thermal shock test 200 cycles 2.3 × 10 ^-2 Ω ^- was (1.9 × 10 ¹ Ωcm).

Example 3 An organic positive temperature coefficient thermistor element was produced in the same manner as in Example 2 except that the surface treatment method of the conductive particles was performed according to the following method. Water 25
1% by mass of acetic acid was added to a mixed solvent of 25 g of ethanol and 25 g of ethanol, and 0.5% by mass of a silane coupling agent was added thereto to prepare a silane coupling solution. This is used as a conductive particle to form a filamentary nickel powder (Type 21).
0) After spraying to 100 g, the surface of the conductive particles was treated by dry explosion.

Initial room temperature resistance value is 1.0 × 10 ⁻⁴ Ω
(8.1 × 10 ⁻⁴ Ωcm), and the resistance change rate was 7 digits. Resistance value after cooling to room temperature is 5.0 × 10 ^-4
Ω (4.1 × 10 ⁻³ Ωcm), which was a slight change.

The initial room temperature resistance value was 8 during measurement of 10 devices.
The number is 5.0 × 10 ⁻⁴ Ω (4.1 × 10 ⁻³ Ωcm), the number is 1.0 × 10 ⁻³ Ω (8.1 × 10 ⁻³ Ωcm),
The variation was small.

The room temperature resistance value after 200 cycles of the thermal shock test was 5.7 × 10 ^-2 Ω (4.6 × 10 ^-1 Ωcm).

[Example 4] The conductive particles used were filamentary nickel powder (manufactured by INCO, trade name Typ).
e255 Nickel powder, average particle size 2.2-2.8 μm
, Apparent density 0.5 to 0.65 g / cm ³ , specific surface area 0.
The same operation as in Example 1 was carried out except that the organic positive temperature coefficient thermistor element was made to be 68 m ² / g).

The initial room temperature resistance value is 5.0 × 10 ⁻⁴ Ω
(4.1 × 10 ⁻³ Ωcm), and the resistance change rate was 8 digits. The resistance value after cooling to room temperature is 1.0 × 10 ^-3
Ω (8.1 × 10 ⁻³ Ωcm), which was a slight change.

Initial room temperature resistance value was 5 during measurement of 10 devices.
5.0 x 10 ^-4 Ω (4.1 x 10 ^-3 Ωcm), 4 x 1.0 x 10 ^-3 Ω (8.1 x 10 ^-3 Ωcm), 1 x 2.0 x It was 10 ⁻³ Ω (1.6 × 10 ⁻² Ωcm), and the variation was small.

The room temperature resistance value after 200 cycles of the thermal shock test was 2.0 × 10 ^-2 Ω (1.6 × 10 ^-1 Ωcm).

[Comparative Example 1] Linear low-density polyethylene polymerized using a metallocene catalyst as a thermoplastic polymer (Mitsui Chemicals, trade name Evolue sp2520, MFR
= 1.7, melting point 121 ° C., paraffin wax as low molecular weight organic compound (Baker Petrolite, trade name Poly
Wax655, melting point 99 ° C, filamentary nickel powder as conductive particles (manufactured by INCO, trade name Type 21)
0 nickel powder, average particle size 0.5 to 1.0 μm, apparent density to 0.8 / cm ³ , specific surface area 1.5 to ^2.5 m ² / g
)It was used.

45% by volume of linear low-density polyethylene, 25% by volume of paraffin wax and 30% by volume of nickel powder were kneaded in a mill at 150 ° C. for 30 minutes.

The kneaded product was formed into a sheet having a thickness of 0.7 mm by a hot press machine at 150 ° C., and both sides were sandwiched by Ni foil electrodes having a thickness of about 30 μm. Was crimped to a total thickness of 0.4 mm. This is 3.6
mm × 9. An Omm shape was punched out to obtain an organic positive temperature coefficient thermistor element.

This device was heated from room temperature to 120 ° C. at 2 ° C./min in a constant temperature bath and cooled, and the resistance value was measured by the 4-terminal method at a predetermined temperature to obtain a temperature-resistance curve. The initial room temperature resistance was 1.0 × 10 ⁻³ Ω, and the resistance rapidly increased at around 90 ° C., and the rate of resistance change was about 10 digits. The resistance value after cooling to room temperature is 1.5 × 10 ^-3 Ω (1.2 ×
It became 10 ^-2 Ωcm).

Further, when the variation in the initial room temperature resistance value was examined, 4 out of 10 element measurements were 1.0 × 10 ⁻³ Ω.
(8.1 × 10 ^-3 Ωcm) 2 pieces are 5.0 × 10 ^-3 Ω
(4.1 × 10 ^-2 Ωcm) One is 7.0 × 10 ^-3 Ω
(5.7 × 10 ^-2 Ωcm) 3 pieces are 1.5 × 10 ^-2 Ω
(1.2 × 10 ⁻¹ Ωcm), and variations were observed.

With respect to this device, -40 ° C. for 30 minutes,
When a thermal shock test was carried out at 85 ° C. for 30 minutes as one cycle, the room temperature resistance value after repeating this cycle for 200 cycles was 579 Ω (4.7 × 10 ³ Ωcm), which was a large increase.

Comparative Example 2 An organic positive temperature coefficient thermistor element was prepared according to Comparative Example 1 except that a silane coupling agent was directly added to the material shown in Comparative Example 1 when the kneaded product was prepared in a mill. did. Silane coupling agent is K
BE1003 was used and the mixing amount was 0.5% by mass.

2 ° C from room temperature to within 120 ° C in a constant temperature bath
The sample was heated and cooled at a temperature of 1 / min, and the resistance value was measured at a predetermined temperature by the 4-terminal method to obtain a temperature-resistance curve. The initial room temperature resistance value was 5.0 × 10 ⁻⁴ Ω (4.1 × 10 ⁻³ Ωcm), and the resistance change rate was about 10 digits. The resistance value after cooling to room temperature was 5.0 × 10 ⁻⁴ Ω (4.1 × 10 ⁻³ Ωcm), which was unchanged.

However, when a thermal shock test was conducted with -40 ° C. for 30 minutes and 85 ° C. for 30 minutes as one cycle, the room temperature resistance value after repeating this cycle 200 times was 59Ω (4
It became 78 Ωcm) and rose.

Further, when the variation in the initial room temperature resistance value was examined, 3 out of 10 element measurements were 1.0 × 10 ⁻³ Ω.
(8.1 × 10 ^-3 Ωcm) 2 pieces are 5.0 × 10 ^-3 Ω
(4.1 × 10 ^-2 Ωcm) 1 piece is 1.0 × 10 ^-2 Ω
(8.1 × 10 ^-2 Ωcm) 3 pieces are 1.5 × 10 ^-2 Ωcm
(1.2 × 10 ^-1 Ωcm) One is 2.0 × 10 ^-2 Ω
(1.6 × 10 ⁻¹ Ωcm), and variation was observed.

Comparative Example 3 An organic positive temperature coefficient thermistor was prepared in the same manner as in Comparative Example 1 except that the composition was 65% by volume of linear low-density polyethylene and 35% by volume of nickel powder.

When a measurement was carried out in the same manner as in Comparative Example 1 to obtain a resistance-temperature curve, the initial room temperature resistance value was 1.5 ×.
A characteristic of 10 ⁻³ Ω (1.2 × 10 ⁻² Ωcm) and a resistance change rate of 8 digits was obtained. The resistance value after cooling to room temperature was 2.0 × 10 ⁻³ Ω (1.2 × 10 ⁻² Ωcm).

Further, the initial room temperature resistance value was 10 × 10 ⁻³ Ω (8.1 × 10 ⁻³ Ωc during measurement of 10 elements).
m) 2 pieces are 3.0 × 10 ^-3 Ω (2.4 × 10 ^-2 Ωc
m) 4 are 5.0 × 10 ^-3 Ω (4.1 × 10 ^-2 Ωc
m) 1.0 x 10 ^-2 Ω (8.1 x 10 ^-2 Ωc
m), and there was variation.

Room temperature resistance after 200 cycles of thermal shock test was significantly increased to 2.5 × 10 ⁻¹ Ω (2.0 Ωcm). From this comparison result, it was found that the effect of the present invention was extremely large.

Comparative Example 4 An organic positive temperature coefficient thermistor element was obtained in the same manner as in Example 4, except that the conductive particles were not surface-treated.

This device was heated and cooled from room temperature to 120 ° C. at 2 ° C./min in a constant temperature bath, and the resistance value was measured at a predetermined temperature by the 4-terminal method to obtain a temperature-resistance curve. Initial room temperature resistance is 1.5 × 10 ^-3 Ω (1.2 × 10 ^-2 Ωcm),
The resistance increased sharply at around 90 ° C., and the rate of resistance change was about 9 digits. Resistance value after cooling to room temperature is 2 × 10
It became ⁻³ Ω (1.6 × 10 ⁻² Ωcm).

Further, when the variation in the initial room temperature resistance value was examined, 10 elements were measured, and 4 elements were 1.5 × 10 ^−3.
Ω (1.2 × 10 ^-2 Ωcm), two are 2.0 × 10 ^-3
Ω (1.6 × 10 ^-2 Ωcm), two are 5.0 × 10 ^-3 Ω
(4.0 × 10 ^-2 Ωcm) One is 1.0 × 10 ^-2 Ω
(8.1 × 10 ^-2 Ωcm) One is 1.5 × 10 ^-2 Ω
(1.2 × 10 ⁻¹ Ωcm), and variations were observed.

With respect to this device, -40 ° C. for 30 minutes,
When a thermal shock test was conducted at 85 ° C. for 30 minutes as one cycle, the room temperature resistance value after repeating this cycle for 200 cycles was 1000Ω (8.1 × 10 ³ Ωcm), which was a large increase.

[0127]

As described above, according to the present invention, it is possible to obtain an organic positive temperature coefficient thermistor which can obtain a sufficiently low room temperature resistance value, has a sufficiently large resistance change rate during operation and non-operation, and is excellent in characteristic stability. Obtainable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the basic structure of an organic positive temperature coefficient thermistor of the present invention.

[Explanation of symbols]

2 Thermistor body 3 electrodes

Claims (6)

[Claims] 1. An organic positive temperature coefficient thermistor containing at least a thermoplastic polymer and conductive particles having spike-like protrusions which are surface-treated with a coupling agent. 2. The coupling agent is added to the conductive particles in an amount of at least 0.1 to 20% by mass.
Organic positive temperature coefficient thermistor described in. 3. The organic positive temperature coefficient thermistor according to claim 1, wherein the coupling agent is a silane coupling agent. 4. The organic positive temperature coefficient thermistor according to claim 1, wherein the conductive particles having the spike-shaped protrusions are connected in a chain. 5. The organic positive temperature coefficient thermistor according to claim 1, wherein the thermoplastic polymer is a polymer polymerized by using a metallocene catalyst. 6. The method according to claim 1, further comprising a low molecular weight compound.
An organic positive temperature coefficient thermistor of any one of to 5.