JP2002208505A - Organic positive temperature coefficient thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic positive temperature coefficient thermistor which can be improved in both reliability an characteristic stability. SOLUTION: An organic positive temperature coefficient thermistor is formed of a matrix consisting of at least two or more kinds of polymer compounds, a low-molecular organic compound, and conductive particles each having spikelike projections, where the polymer matrix contains thermoplastic elastomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTC (positive temperature coefficient) which is used as a temperature sensor or an overcurrent protection element and whose resistance value increases with an increase in temperature.
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 thermoplastic polymer are known in the art, and are disclosed in U.S. Pat.
No. 351882 and the like. It is thought that the increase in the resistance value is due to the fact that the crystalline polymer expands with melting and cuts the conductive path of the conductive fine particles.

[0003] Organic positive temperature coefficient thermistors can be used for overcurrent / heating protection elements, self-regulating heating elements, temperature sensors, and the like. The characteristics required of these are that the room temperature resistance during non-operation is sufficiently low, the rate of change between the room temperature resistance and the resistance during operation is sufficiently large, and the change in resistance due to repeated operation is small. Can be

In order to satisfy such required characteristics, an organic positive temperature coefficient thermistor using a low molecular weight organic compound such as a wax and using a thermoplastic polymer as a matrix as a binder has been proposed. As such an organic positive temperature coefficient thermistor, for example, polyisobutylene / paraffin wax / carbon black (F. Bueche, J. Appl. Phy.
s., 44 , 532, 1973), styrene-butadiene rubber / paraffin wax / carbon black system (F. Bueche, J. Poly)
mer Sci., 11 , 1319, 1973), low-density polyethylene / paraffin wax / carbon black system (K.Ohe et al., Jpn.
J. Appl. Phys., 10 , 99, 1971). In addition, Japanese Patent Publication 62-165
No. 23, Tokuhei 7-109786, 7-48396, JP-A-62-5118
No. 4, No. 62-51185, No. 62-51186, No. 62-51187, JP-A No. 1-231284, No. 3-132001, No. 9-27383, No. 9-694
No. 10 also discloses a self-temperature controlled heating element, a current limiting element, and the like using an organic positive temperature coefficient thermistor using a low molecular weight organic compound. In these cases, it is considered that the resistance value increases due to the melting of the low molecular weight organic compound.

[0005] The use of a low-molecular organic compound generally has a higher degree of crystallinity than a polymer, and thus has the advantage that the rise when the resistance is increased by increasing the temperature becomes steep. In addition, since polymers tend to take a supercooled state, they usually show hysteresis such that the temperature at which the resistance value decreases when the temperature rises is lower than the temperature at which the resistance value increases when the temperature rises. By using this, this hysteresis can be suppressed. Further, when low-molecular organic compounds having different melting points are used, the temperature at which the resistance increases (operating temperature) can be easily controlled. In the case of polymers, the difference in molecular weight and crystallinity, and the change in melting point due to copolymerization with a comonomer, can change the operating temperature. PTC characteristics may not be obtained. This tends to be more noticeable especially when the operating temperature is set to 100 ° C. or lower.

However, in the organic positive temperature coefficient thermistor disclosed in the above document, since carbon black or graphite is used as the conductive particles, a low initial (room temperature) resistance and a large resistance change rate are not compatible. . In these documents, Jpn.J.Appl.Phys., Vol10, p.99,1971
Although an example in which the specific resistance (Ω · cm) has been increased to 10 ⁸ Ω · cm is shown, the specific resistance at room temperature is very high at 10 ⁴ Ω · cm, and particularly, an overcurrent protection element and a temperature sensor. Not practical to use. Further, the increase in the resistance value (Ω) or the specific resistance value (Ω · cm) in other documents is 10 ¹ Ω.
It is in the range from the following to about 10 ⁴ Ω, and the room temperature resistance is not sufficiently low.

Japanese Patent Application Laid-Open No. Hei 5-47503 discloses an organic positive temperature coefficient thermistor having a crystalline polymer and conductive particles having spike-like projections. U.S. Pat. No. 5,378,407 also discloses an organic positive temperature coefficient thermistor comprising filamentary Ni having spike-shaped protrusions and a crystalline polyolefin, olefin copolymer or fluoropolymer.

[0008] However, in these devices, although the effect of achieving both a low initial resistance and a large change in resistance is improved, the hysteresis point is insufficient because a low molecular organic compound is not used as a working material, and particularly, a temperature sensor is not used. It is not suitable for such uses. In addition, when the heating is further performed after the resistance increases during operation, the NTC characteristic (negative temperature coefficient o) in which the resistance value decreases as the temperature increases.
f resistivity). Note that the above publication and the above specification do not suggest using a low molecular weight organic compound at all. Moreover, these have operating temperatures above 100 ° C. Operating temperature is 60-7
Some of them are 0 ° C., however, these are not practical because their characteristics due to repeated operation are unstable.

The present inventors have disclosed in Japanese Patent Application Laid-Open No. H11-168005.
In the publication, thermoplastic polymer matrix, low molecular
Organic compound and conductive particles having spike-like protrusions
We propose an organic positive temperature coefficient thermistor containing. This one
The reason is that the room temperature resistivity is 8 × 10 ^-2Ω ・ cm or less, low enough
The resistance change rate during operation and non-operation is as large as 11 digits or more,
Furthermore, the hysteresis of the temperature-resistance curve is small. I
The operating temperature is 40 to 100 ° C. Low room temperature
Both the specific resistance and the large resistance change are compatible, and the operating temperature is low.
Especially suitable for overcurrent and heating protection elements of secondary batteries
Can be used.

[0010] The present inventors have further found that the low molecular weight organic compound has a low melting point and a low melt viscosity, which results in insufficient characteristic stability. Since the operation and restoration of the element repeat melting and solidification, it is considered that the crystal state and the dispersion state change at that time. In particular,
When a high-temperature and high-humidity acceleration test or an intermittent load test is performed, an increase in resistance appears remarkably. To improve this, Japanese Patent Application Laid-Open
In JP-A-200704, studies have been made to use at least two types of polymer matrices.

US Pat. No. 5,378,407 discloses that crystalline polyolefin, olefin-based copolymer, or fluoropolymer can be blended with an elastomer, an amorphous thermoplastic polymer, or another crystalline polymer. No effects or examples are shown. JP-A-54-16697 discloses at least 2
A crystalline thermoplastic polymer component having a melting point of two separated crystals, and a PTC composition containing an elastomer are disclosed, but only Rybon black is disclosed as conductive particles, as in the present invention. Neither low room temperature resistance nor high resistance change rate is achieved. In addition, there is no discussion on thermal shock resistance or use of low molecular weight organic compounds.

Further, Japanese Patent Application Laid-Open No. 63-279589,
JP-A-5-266974, JP-A-8-13843
9, JP-A-8-316005, JP-A-10-316005
-334733 also discloses a PTC composition containing an elastomer, but does not mention the use of conductive particles having spike-like projections or a low-molecular organic compound as in the present application, and thus has a low level. The room temperature resistance and the large resistance change rate are not compatible.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to improve the reliability of an organic positive temperature coefficient thermistor and to improve the stability of the characteristics.

[0014]

(1) A matrix comprising at least two or more polymer compounds, a low molecular organic compound, and conductive particles having spike-like projections, wherein the polymer matrix is a thermoplastic elastomer. Organic positive temperature coefficient thermistor containing. (2) The organic positive temperature coefficient thermistor according to (1), wherein the thermoplastic elastomer is contained in an amount of 2 to 60% by mass based on the entire matrix. (3) The melting point of the low molecular weight organic compound is from 40 ° C. to 20
The organic positive temperature coefficient thermistor according to (1) or (2), wherein the temperature is 0 ° C. (4) The organic positive temperature coefficient thermistor according to any one of (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 (1) to (4), wherein said low molecular weight organic compound is segregated in a polymer matrix. (6) The above (1) to (10) which are transferable circuit elements of a secondary battery
The organic positive temperature coefficient thermistor according to any of (5).

[0015]

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

It is considered that the use of spike-shaped conductive particles makes it easier for a retunnel current to flow due to the shape thereof, and that the room-temperature resistance can be reduced as compared with a spherical conductive particle. Further, since the distance between the conductive particles is larger than that of the spherical particles, the resistance change can be increased.

In the present invention, the hysteresis of the temperature-resistance curve is reduced as compared with the case where the operation is performed by melting the crystalline polymer, since the resistance value is increased by expansion caused by the melting of the low molecular weight organic compound. If low-molecular-weight organic compounds having different melting points are used, the operating temperature can be easily adjusted.

Further, the present inventors have found that the use of a thermoplastic elastomer for at least a part of the polymer matrix further improves the long-term durability of the device.

The polymer matrix used in the present invention can prevent the element from being deformed when the low molecular organic compound having a low melt viscosity operates and melts. In addition, it was found that when a plurality of polymer matrices were used and at least one of them was a thermoplastic elastomer, the thermal shock resistance was improved, and a low room temperature resistance and a large resistance change were stably maintained for a long period of time.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The organic positive temperature coefficient thermistor of the present invention comprises a plurality of types of polymer matrices, low molecular weight organic compounds, and conductive particles having spike-like projections, and contains a thermoplastic elastomer as the polymer matrix. Features.

The effects of using a thermoplastic elastomer are as follows. Low molecular organic compounds flow very easily due to their very low melt viscosity, and after the resistance increases at operating temperature, the current continues to flow, causing the conductive particles to rearrange in the matrix and operate and increase resistance. The NTC phenomenon in which the resistance decreases may occur, or the temperature at which the resistance starts to decrease when the temperature drops may be higher than the temperature at which the resistance starts to increase when the temperature rises. This occurs remarkably when only a high melting point thermoplastic polymer such as high density polyethylene is used as the matrix.

On the other hand, when a matrix having a melting point relatively close to the melting point of the low molecular weight organic compound, for example, a low melting point polyolefin is used, melting starts immediately after the low molecular weight organic compound is melted. In addition, the rearrangement of the conductive particles can be suppressed, and the above-described defect can be suppressed. However, when the operation is repeated, a remarkable increase in the room temperature resistance value is observed. Low melting point polyolefins have similar melting points when operated by melting low molecular organic compounds
One part melts. Since the low-melting-point polyolefin contains many side chains or is a copolymer, the time required for crystallization is longer than that of a homopolymer containing no side chains. Therefore, once melted and then solidified, it cannot be sufficiently crystallized, contains a large amount of amorphous portion, the entire system remains expanded, and it is considered that the room temperature resistance gradually increases when the operation is repeated.

The present inventors have disclosed JP-A-2000-200704.
In the publication, at least two types of polymer matrices having different melting points, specifically, a thermoplastic polymer having a melting point higher than that of a low-molecular organic compound but a relatively low melting point, and more than a thermoplastic polymer having a relatively low melting point It has been shown that the use of a high melting point thermoplastic polymer can avoid the disadvantages when only one type of thermoplastic polymer is used.

However, Japanese Patent Application Laid-Open No. 2000-200
It has been found that the configuration of Japanese Patent No. 704 is insufficient in characteristic stability. In particular, deterioration is remarkable in a thermal shock test in which rapid thermal expansion and contraction are repeated. In the present invention, it has been found that the above-mentioned drawbacks can be greatly improved by making a part of the polymer matrix a thermoplastic elastomer and giving the material an appropriate elasticity.

A thermoplastic elastomer is a polymer material that undergoes elastic deformation at room temperature but undergoes plastic deformation when the temperature rises. The molecule has a soft block that shows rubber-like elastic deformation and a hard block that plastically deforms when the temperature rises, and these are block or graft copolymerized. There is also a blend made of a soft rubber component and a hard resin. Specifically, there are polyolefin, polystyrene, polyurethane, polyamide, fluoropolymer, ionomer and the like, and polyolefin and polystyrene are particularly preferable. It is desirable that the melting point be higher than the melting point of the low-molecular organic compound used by 10 ° C. or more.

Melt viscosity (MFR) of thermoplastic elastomer
Is not particularly limited, 230 ° C., 2.16 kg
0.1 to 50g / 10min under load, same temperature 10k
It can be used up to about 5 to 50 g / 10 min under a g load. Further, its melting point is desirably about 100 to 180 ° C.

Specifically, as an olefin type, hard segments such as polypropylene and polyethylene, and soft segments such as polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, EPD
M and the like, a blend of these, and a further cross-linked of the blend can be used.

As the styrene type, polystyrene or the like is used for the hard segment, and polybutadiene, polyisoprene, or a hydrogenated product thereof, EP is used for the soft segment.
Examples include those having DM and the like, which are block copolymerized.

These styrene-based thermoplastic elastomers have a micro-layer separation structure because both segments are incompatible. Therefore, when a high molecular matrix and a low molecular organic compound to be used together are selected in consideration of compatibility, long-term reliability is improved by segregating and fixing a low molecular organic compound that easily flows in a molten state in the matrix. It is thought to be effective. For example, if polystyrene is used in combination with the polymer matrix and hydrocarbon wax is used as the low-molecular organic compound, the wax can be selectively dispersed in the rubber portion that is a soft segment of the styrene elastomer.

Among these, polypropylene-E
PDM-based olefin-based elastomers and hydrogenated polyisoprene-based styrene-based elastomers are preferred.

The content of the thermoplastic elastomer is preferably about 2 to 60% by mass relative to the whole matrix,
In particular, it is about 5 to 40%.

As the polymer matrix, both thermoplastic and thermosetting can be used. Examples of the thermoplastic polymer matrix include polyolefin (eg, polyethylene), olefin-based copolymer (eg, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer), halogen-based polymer, polyamide, polystyrene, polyacrylonitrile, polyethylene oxide,
Examples include polyacetal, thermoplastically modified cellulose, polysulfones, thermoplastic polyesters (such as PET), polyethyl acrylate, polymethyl methacrylate, and the like.

Specifically, high-density polyethylene [for example, Hyzex 2100JP (manufactured by Mitsui Petrochemical), Marlex 6003 (manufactured by Philips), HY540 (manufactured by Nippon Polychem), etc .; Trade name LC500 (manufactured by Nippon Polychem), trade name DYNH-1 (manufactured by Union Carbide), etc., medium density polyethylene [for example, trade name 260]
4M (manufactured by Gulf), etc., ethylene-ethyl acrylate copolymer [for example, DPD6169 (manufactured by Union Carbide), etc.], ethylene-vinyl acetate copolymer [for example, LV241 (manufactured by Nippon Polychem)
Etc.], ethylene-acrylic acid copolymer [for example, EAA455 (trade name, manufactured by Dow Chemical Co., Ltd.)], ionomer [for example, Himilan 1555 (trade name, manufactured by DuPont Polychemical Co., Ltd.)], polyvinylidene fluoride [for example, product] Kynar 461 (Elf Atochem) and vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer [e.g., Kynar ADS (Elf Atochem)].

Among these, polyolefin is preferred, and polyethylene is particularly preferred. Each grade of high-density, linear low-density, and low-density polyethylene can be used. Among them, high-density, linear low-density polyethylene is preferable. Its melt viscosity (MFR) is 15.0 g /
It is preferably at most 10 min, particularly preferably at most 8.0 g / 10 min. Further, its melting point is desirably 10 ° C. or more higher than that of the low molecular weight organic compound in order to suppress thermal deformation of the device.

The thermosetting polymer matrix is not particularly limited, but epoxy resin, unsaturated polyester resin, polyimide, polyurethane, phenol resin and silicone resin are preferably used.

The epoxy resin is obtained by curing (crosslinking) an oligomer having a reactive epoxy group at a terminal (molecular weight of several hundreds to about 10,000) with various curing agents, and is a glycidyl ether type represented by bisphenol A, It is classified into glycidyl ester type, glycidylamine type and alicyclic type. Depending on the application, a trifunctional or higher polyfunctional epoxy resin can also be used. In the present invention, among these, it is preferable to use a glycidyl ether type, especially a bisphenol A type. The epoxy equivalent of the epoxy resin used is 1
About 00 to 500 is preferable. The curing agent is classified into a polyaddition type, a catalyst type, and a condensation type according to the reaction mechanism. In the polyaddition type, the curing agent itself is added to an epoxy group or a hydroxyl group, and examples thereof include polyamine, acid anhydride, polyphenol, polymercaptan, and isocyanate. The catalyst type serves as a polymerization catalyst for epoxy groups, and includes tertiary amines, imidazoles and the like. The condensation type is cured by condensation with a hydroxyl group, and includes a phenol resin and a melamine resin.
In the present invention, as a curing agent for the bisphenol A type epoxy resin, it is preferable to use a polyaddition type, particularly a polyamine type and an acid anhydride. Curing conditions may be determined as appropriate.

Such epoxy resins and curing agents are commercially available, and include, for example, Epicoat (resin), Epicure, Epomate (curing agent) manufactured by Yuka Shell Epoxy, and Araldite manufactured by Ciba Geigy.

The unsaturated polyester resin is obtained by dissolving a polyester (molecular weight: about 1,000 to 5,000) mainly composed of an unsaturated dibasic acid or a dibasic acid and a polyhydric alcohol in a vinyl monomer which functions as a crosslink. And by curing an organic peroxide such as benzoyl peroxide as a polymerization initiator. If necessary, the composition may be cured by using a polymerization accelerator in combination. As a raw material of the unsaturated polyester used in the present invention, as the unsaturated dibasic acid, maleic anhydride,
Fumaric acid is preferred, and phthalic anhydride as the dibasic acid,
Isophthalic acid and terephthalic acid are preferred, and propylene glycol and ethylene glycol are preferred as polyhydric alcohols. As the vinyl monomer, styrene, diallyl phthalate and vinyl toluene are preferred. The blending amount of the vinyl monomer may be appropriately determined, and is usually about 1.0 to 3.0 mol per 1 mol of fumaric acid residue. Also,
Known polymerization inhibitors such as quinones and hydroquinones are added for the purpose of preventing gelation and adjusting the curing properties in the synthesis step. Curing conditions may be determined as appropriate.

Such unsaturated polyester resins are commercially available and include, for example, Epolac manufactured by Nippon Shokubai, Polyset manufactured by Hitachi Chemical, Polylite manufactured by Dainippon Ink and Chemicals, and the like.

Polyimides are roughly classified into a condensation type and an addition type depending on the production method, and a bismaleimide type polyimide which is an addition polymerization type polyimide is preferable. Bismaleimide-type polyimides are homopolymerized, reacted with other unsaturated bonds, Michael addition reaction with aromatic amines or with diene.
It can be cured using the Diels-Alder reaction or the like. In the present invention, a bismaleimide-based polyimide resin obtained by an addition reaction between a bismaleimide and an aromatic diamine is particularly preferable. Examples of aromatic diamines include diaminodiphenylmethane. The synthesis and curing conditions may be determined as appropriate.

Such a polyimide is commercially available,
For example, there are Imidaroy manufactured by Toshiba Chemical Co., Ltd., and kerimide manufactured by Ciba Geigy Co., Ltd.

The polyurethane is obtained by a polyaddition reaction between a polyisocyanate and a polyol. As the polyisocyanate, there are an aromatic type and an aliphatic type, and an aromatic type is preferable, and 2,4- or 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate and the like are preferably used. Polyols include polyether polyols such as polypropylene glycol, polyester polyols, and acrylic polyols, with polypropylene glycol being preferred.
The catalyst may be an amine (a tertiary amine such as triethylenediamine and an amine salt), but it is preferable to use an organic metal such as dibutyltin dilaurate and stannas octoate. In addition, a cross-linking agent such as a polyhydric alcohol and a polyamine may be used in combination as an auxiliary material. Synthesis and curing conditions may be determined as appropriate.

Such polyurethanes are commercially available, for example, Sumidur manufactured by Sumitomo Bayer Urethane Co., Ltd.
There are NP series manufactured by Mitsui Toatsu Chemicals, Coronate manufactured by Nippon Polyurethane, and the like.

The phenol resin is obtained by reacting phenol with an aldehyde such as formaldehyde, and is roughly classified into a novolak type and a resol type according to the synthesis conditions.
The novolak type formed under an acidic catalyst is cured by heating together with a crosslinking agent such as hexamethylenetetramine, and the resol type generated under a basic catalyst is cured alone by heating or in the presence of an acid catalyst. In the present invention, either one may be used. Synthesis and curing conditions may be determined as appropriate.

Such phenolic resins are commercially available, for example, Sumicon manufactured by Sumitomo Bakelite Co., Ltd., stand lights manufactured by Hitachi Chemical Co., Ltd., and Tecolite manufactured by Toshiba Chemical Co., Ltd.

The silicone resin is composed of repeating siloxane bonds, and is mainly obtained by hydrolysis or polycondensation of an organohalosilane; alkyd-modified; polyester-modified; acrylic-modified; epoxy-modified;
Phenol-modified, urethane-modified, melamine-modified silicone resins, silicone rubber obtained by crosslinking linear polydimethylsiloxane or its copolymer with an organic peroxide, etc., condensation and addition type that can be cured at room temperature (RTV) There are silicone rubber and the like.

Such silicone resins are commercially available, and include, for example, various silicone rubbers and silicone resins manufactured by Shin-Etsu Chemical, Toray Dow Corning, and Toshiba Silicone.

The thermosetting resin to be used can be appropriately selected according to the desired performance and application. Among them, it is preferable to use an epoxy resin or an unsaturated polyester resin. Further, a polymer obtained by mutually reacting two or more kinds may be used.

When the thermosetting polymer matrix and the thermoplastic polymer matrix are used in combination, the mass ratio of the thermosetting polymer matrix to the thermoplastic polymer matrix is 1: 5 to 9: 1, especially 1: 5. It is preferably from 4 to 8: 1. If the amount of the thermoplastic polymer matrix is more than this, the stability of the initial resistance tends to decrease. If the amount of the thermoplastic polymer matrix is less than this, the stability under high temperature and high humidity tends to deteriorate.

The low molecular weight organic compound used in the present invention has a molecular weight of up to about 2000, preferably up to about 1000,
More preferably, it is not particularly limited as long as it is a crystalline substance of 200 to 800, but is preferably a solid substance at normal temperature (temperature of about 25 ° C.).

Examples of the low molecular weight organic compound include waxes (specifically, natural waxes such as petroleum waxes such as paraffin wax and microcrystalline wax, vegetable waxes, animal waxes, and mineral waxes);
Fats and oils (specifically, fats or solid fats)
and so on. Components of waxes and fats and oils include hydrocarbons (specifically, alkane linear hydrocarbons having 22 or more carbon atoms) and fatty acids (specifically, alkane linear hydrocarbons having 12 or more carbon atoms). Fatty acids), fatty acid esters (specifically, methyl esters of saturated fatty acids obtained from saturated fatty acids having 20 or more carbon atoms and lower alcohols such as methyl alcohol), fatty acid amides (specifically, oleic acid amide, Unsaturated fatty acid amides such as erucamide, 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 paraffin and the like, which can be used alone or in combination as a low molecular weight organic compound. The low-molecular 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 organic compounds are commercially available, and commercially available products can be used as they are.

In the present invention, the operating temperature is preferably 200
° C. or less, more preferably 100 ° C. or less, the purpose of the low-molecular 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. These include, paraffin wax (e.g., tetracosane C ₂₄ H _50; mp49~52 ℃, hexatriacontane C ₃₆ H _74; mp73 ℃, trade name HNP-10 (Nippon Seiro Co., Ltd.); mp75 ℃, HNP-3 (manufactured by Nippon Seiro);
mp66 ° C.), microcrystalline wax (for example, trade name Hi-Mic-1080 (manufactured by Nippon Seiwa); mp83 ° C., Hi-Mic-1045 (manufactured by Nippon Seiwa); mp70 ° C., Hi-Mic2045 (Japan) Mp64 ° C, Hi-Mic3090 (manufactured by Nippon Seiwa); mp89 ° C, serrata 104 (manufactured by Nippon Oil Refining); mp96 ° C, 155 microwax (manufactured by Nippon Oil Refining); mp70 ° C, etc. ), Fatty acids (for example, behenic acid (Nippon Seika); mp81 ° C, stearic acid (Nippon Seika); mp72 ° C, palmitic acid (Nippon Seika);
mp 64 ° C.), fatty acid esters (for example, arachiic acid methyl ester (manufactured by Tokyo Chemical Industry); mp 48 ° C., etc.),
Fatty acid amides (for example, oleic acid amide (manufactured by Nippon Seika); mp76 ° C.) and the like. Further, polyethylene wax (for example, trade name: Mitsui High Wax 110 (manufactured by Mitsui Petrochemical Industries, Ltd .; mp100 ° C.)), stearamide (mp109 ° C.), behenamide (mp111)
° C), N-N'-ethylenebislauric amide (mp
157 ° C), N-N'-dioleyladipamide (mp 119 ° C), N-N'-hexamethylenebis-1
There is also 2-hydroxystearic acid amide (mp 140 ° C.). It is a compounded wax obtained by mixing a resin with paraffin wax or a mixture of the compounded wax and a microcrystalline wax having a melting point of 40 to 20.
What is set to 0 degreeC can also be used preferably.

One or more low molecular weight organic compounds can be selected and used depending on the operating temperature and the like.

The content of the low molecular organic compound is 0.1 to 4 times the total mass of the polymer matrix (including the curing agent and the like).
Preferably, it is 0.2 times, especially 0.2 to 2.5 times. When the mixing ratio is reduced and the content of the low molecular weight organic compound is reduced, it becomes difficult to obtain a sufficient resistance change rate.
Conversely, when the mixing ratio is increased and the content of the low molecular weight organic compound is increased, the elementary body is greatly deformed when the low molecular weight compound is melted, and mixing with the conductive particles becomes difficult.

The organic positive temperature coefficient thermistor of the present invention has endothermic peaks near the melting point of each of the thermoplastic polymer matrices used and the melting point of the low molecular weight organic compound by differential scanning calorimetry (DSC). As a result, the high-melting thermoplastic polymer matrix, the low-melting thermoplastic polymer matrix, and the low-molecular organic compound, or the thermosetting polymer matrix, the thermoplastic polymer matrix, and the low-molecular organic compound are independently formed. It is considered to have a sea-island structure that exists in a dispersed manner.

The conductive particles having spike-like projections used in the present invention are formed from primary particles each having one sharp projection, and have a height of 1/3 to 1/50 of the particle diameter. Conical spike-like projections on one particle (usually 1
0 to 500). The material is metal,
Particularly, Ni and the like are preferable.

Such conductive particles may be a powder in which one particle is present individually, but the number of primary particles is 10 to 10.
It is preferable that about 1000 chains are connected in a chain to form secondary particles. Some primary particles may be present in the chain. An example of the former is a spherical nickel powder having spike-shaped protrusions, and the product name is INCO Type.
It is commercially available as e123 nickel powder (manufactured by Inco Corporation), has 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.
~0.44m is about ² / g.

Further, as an example of the latter, which is preferably used, there is a filamentous nickel powder having a trade name of IN.
It is commercially available as CO Type 210, 255, 270, 287 nickel powder (manufactured by INCO), and among them, INCO Type 210, 255 is preferable.
The average particle size of the primary particles is preferably 0.1
μm or more, more preferably about 0.2 μm or more and 4.0 μm or less. Among these, the average particle diameter of the primary particles is most preferably 0.4 or more and 3.0 μm or less, and the average particle diameter of the primary particles is 0.1 μm or more and less than 0.4 μm is 50% by mass.
The following may be mixed. The apparent density is 0.3 ~
About 1.0 g / cm ³ , specific surface area is 0.4 to ^2.5 m ² / g
It is about.

The average particle size in this case is measured by the fish-sub-sieve 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-shaped protrusions, carbon black, graphite, carbon fiber,
Carbon-based conductive particles such as metal-coated carbon black, graphitized carbon black, metal-coated carbon fibers, metal particles such as spheres, flakes, and fibers, particles of different metal-coated metals (such as silver-coated nickel), tungsten carbide, and nitrided Ceramic-based conductive particles such as titanium, zirconium nitride, titanium carbide, titanium boride, and molybdenum silicide, and conductive potassium titanate whiskers described in JP-A-8-31554 and 9-27383. May be added. It is preferable that such conductive particles be 25% by mass or less of the conductive particles having spike-shaped protrusions.

The content of the conductive particles is preferably 1.5 to 8 times the total mass of the polymer matrix and the low molecular weight organic compound (the total mass of the organic components including the curing agent and the like). When the mixing ratio is reduced and the content of the conductive particles is reduced, the room temperature resistance during non-operation cannot be sufficiently reduced. Conversely, when the content of the conductive particles increases, it becomes difficult to obtain a large rate of change in resistance, and
Uniform mixing becomes difficult, and it becomes difficult to obtain stable characteristics.

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

The kneading of the thermoplastic polymer matrix, the thermoplastic elastomer, the low molecular weight organic compound, and the conductive particles may be performed by a known method. When the polymer matrix is entirely thermoplastic, materials other than the thermoplastic elastomer are used. Temperature above the melting point of the thermoplastic polymer with the highest melting point,
Preferably, kneading is performed at a temperature higher by 5 to 40 ° C. for about 5 to 90 minutes using a known mill or roll. Although it depends on the amount of the thermoplastic elastomer, even if the melting point of the elastomer is higher than that of the thermoplastic polymer having the highest melting point, the elastomer is relatively soft even at a temperature lower than the melting point. There is no. In order to prevent thermal degradation, kneading may be performed at a temperature as high as possible but lower than the melting point of the thermoplastic polymer other than the elastomer. Alternatively, the polymer matrix and the low-molecular-weight organic compound may be melt-mixed in advance or dissolved and mixed in a solvent.

When the thermoplastic polymer matrix, the thermoplastic elastomer, the low molecular weight organic compound and the conductive particles are mixed by a solution method, at least one of the thermoplastic polymer matrix, the thermoplastic elastomer and the low molecular weight organic compound is dissolved. The solvent may be used to disperse the remaining thermoplastic polymer matrix, thermoplastic elastomer, low molecular weight organic compound, and conductive particles in this solution.

The kneaded material is pressed into a sheet having a predetermined thickness. The molding may be performed by an injection method, an extrusion method, or the like. After molding, a crosslinking treatment may be performed as necessary. Examples of the crosslinking method include radiation crosslinking, chemical crosslinking with an organic peroxide, and water crosslinking in which a silane coupling agent is grafted and a silanol group is condensed and reacted. Water crosslinking is preferable. Finally, a metal electrode such as Cu or Ni is thermocompression-bonded or a conductive paste is applied to form a thermistor element. Press molding and electrode formation may be performed simultaneously.

In the present invention, a mixture of a thermoplastic polymer matrix, a low molecular weight organic compound and conductive particles is subjected to a crosslinking treatment with a silane coupling agent having a vinyl group or a (meth) acryloyl group and an alkoxy group. Is preferred. As a result, the characteristic stability during storage and repetitive operation is significantly improved.

By forming a crosslinked structure between the polymer matrix and the low molecular weight organic compound, the shape is maintained by the polymer matrix, aggregation and segregation of the low molecular weight organic compound which repeats melting and solidification during operation are suppressed, and It is considered that the characteristic stability of the characteristic thermistor is improved. In addition, it is considered that the coupling agent forms a chemical bond between the organic-inorganic material and not only the above-mentioned cross-linking of the organic matrix, but also has a great effect on modifying the interface. By treating a mixture of a polymer matrix, a low-molecular organic compound and conductive particles with a silane-based coupling agent, an interface of a polymer matrix-conductive particles, an interface of a low-molecular organic compound-conductive particles, a polymer matrix It is considered that the interface of the metal electrode, the low molecular organic compound, the interface of the metal electrode, and the interface of the low melting polymer matrix and the high melting polymer matrix are strengthened and further contribute to the improvement of the stability of characteristics.

In the present invention, the coupling agent is grafted to the polymer matrix and the low molecular weight organic compound via a group having a carbon double bond (C （C),
It is crosslinked by dealcoholation and dehydration condensation in the presence of water. The reaction formula is shown below.

[0071]

Embedded image

The silane coupling agent can be condensed by dealcoholation and dehydration, and has an alkoxy group capable of chemically bonding to an inorganic oxide and an organic material.
It has a vinyl group or a (meth) acryloyl group chemically bonded in the molecule. As a silane coupling agent,
C = C bond-containing trialkoxysilanes are preferred.

The alkoxy group preferably has a small number of carbon atoms, and particularly preferably a methoxy group or an ethoxy group. The group containing a C ＝ C bond is a vinyl group or a (meth) acryloyl group, with a vinyl group being preferred. These groups are directly S
i is bonded through a carbon chain having 1 to 3 carbon atoms
It may be bonded to i.

The silane coupling agent is preferably a liquid at room temperature.

Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ- (meth) acryloxypropyltrimethoxysilane, γ- ( (Meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane and the like. Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferable.

The coupling treatment is carried out in a kneaded mixture of a thermoplastic polymer matrix, a low molecular weight organic compound and conductive particles, wherein 0.1 to 5% by weight of silane of the total weight of the thermoplastic polymer and the low molecular weight organic compound is added. System coupling agent,
After mixing well, water crosslinking is performed. When the amount of the coupling agent is smaller than this, the effect of the cross-linking treatment is reduced, and when the amount is larger, the effect is not changed. When a silane coupling agent having a vinyl group is used, an organic peroxide of 5 to 20% by weight of the coupling agent, for example,
2,2-di- (t-butylperoxy) butane, dicumyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane and the like are mixed together, and the Grafting to an organic substance, that is, a thermoplastic polymer and a low molecular weight organic compound. The addition of the silane coupling agent is performed after the thermoplastic polymer, the low molecular weight organic compound, and the conductive particles are sufficiently uniformly kneaded.

After the kneaded material is press-molded, a crosslinking treatment is performed in the presence of water. Specifically, dibutyltin dilaurate, dioctyltin dilaurate as a catalyst,
Using a metal carboxylate such as tin acetate, tin octoate, or zinc octoate, the compact is immersed in warm water for 6 to 8 hours. Further, the catalyst can be kneaded in a thermistor body and cross-linking can be performed under high temperature and high humidity. As the catalyst, it is particularly preferable to use dibutyltin dilaurate. The crosslinking temperature is preferably lower than the melting point of the low molecular weight organic compound in order to enhance the stability of the characteristics such as the repetitive operation. After the crosslinking treatment, the molded body is dried, and Cu,
A thermistor element can be obtained by thermocompression bonding of a metal electrode such as Ni or applying a conductive paste or the like.

When a thermosetting polymer matrix is used, a predetermined amount of a pre-cured thermosetting resin, a thermoplastic elastomer, a low molecular organic compound, and conductive particles having spike-shaped projections are mixed and dispersed to form a paint. And Mixing and dispersion may be performed according to a known method, and various types of stirrers, dispersers, paint rolls, and the like can be used. If bubbles are mixed during mixing, vacuum degassing is performed. Various solvents such as aromatic hydrocarbons, ketones, and alcohols can be used for adjusting the viscosity. This is poured between metal foil electrodes such as nickel or copper, or re-sheeted by application such as screen printing, and then cured under a predetermined heat treatment condition of a thermosetting resin. There is also a method in which pre-curing is performed at a relatively low temperature and then main curing is performed at a high temperature. An electrode may be formed by applying a conductive paste or the like to a mixture obtained by curing only the mixture into a sheet. The obtained sheet molded body is punched into a desired shape to form a thermistor element.

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

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

For improving the durability, see Japanese Patent Application Laid-Open No.
Titanium oxide, iron oxide, zinc oxide, silica, magnesium oxide, alumina, chromium oxide, barium sulfate, calcium carbonate, calcium hydroxide, and lead oxide described in JP-A-6-68963. An inorganic solid having a high relative dielectric constant, specifically, barium titanate, strontium titanate, potassium niobate, or the like may be added.

In order to improve the withstand voltage, see Japanese Patent Application Laid-Open No. 4-7438.
Boron carbide and the like described in JP-A No. 3 may be added.

For improving the strength, see Japanese Patent Application Laid-Open No. 5-74603.
Hydrated alkali titanate described in JP-A-8-17563, 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
No. 6,098,098, alkali metal halides, melamine resins, benzoic acid, dibenzylidene sorbitol, metal benzoate described in Japanese Patent Publication No. 6-76511, and JP-A-7-6864. Talc, zeolite, dibenzylidene sorbitol, sorbitol derivative (gelling agent) described in JP-A-7-263127, asphalt, and further sodium bis (4-t-butylphenyl) phosphate and the like are added. Is also good.

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

As a metal damage inhibitor, JP-A-7-6864
Irganox MD1024
(Made by Ciba-Geigy) or the like may be added.

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

Other than these, zinc sulfide, basic magnesium carbonate, aluminum oxide, calcium silicate, magnesium silicate, aluminosilicate clay (mica, talc, kaolinite, montmorillonite, etc.), glass powder, glass flake, glass fiber , Calcium sulfate or the like may be added.

These additives include a polymer matrix,
It is preferably 25% by weight or less of the total weight 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 not operating and has a room temperature specific resistance of 10%.
^-3 to 10 ^-1 Ω · cm, the resistance rises steeply during operation, and the resistance change rate 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 includes a thermistor body 2 having at least a thermoplastic polymer matrix, a thermoplastic elastomer, a low molecular weight organic compound, and conductive particles, and a pair of thermistor bodies 2 sandwiched therebetween. Electrodes 3 are arranged. The example shown is
It shows an example of the cross-sectional shape of the thermistor, and various modifications are possible without departing from the spirit of the present invention. The plane shape may be a circle, a square, or any other optimum shape depending on the required characteristics and specifications.

[0092]

[Example 1] A linear low-density polyethylene (trade name: UJ9, manufactured by Nippon Polychem) was used as a polymer matrix.
60, MFR = 5.0 g / 10min (190 ° C., 2.16 kg load), density = 0.935 g / cm ³ , melting point 135 ° C.), olefin-based thermoplastic elastomer (Mitsui Petrochemical, trade name Mirastomer 6030N) MFR = 50 g / 10min
(At 230 ° C., 10 kg load), density = 0.890 g / cm ³ ,
Melting point: 165 ° C.); paraffin wax (HNP-10, manufactured by Nippon Seiwa Co., Ltd .; melting point: 75 ° C.) as a low-molecular organic compound; filamentary nickel powder (NIC: conductive particles)
Company O, trade name Type255 nickel powder, average particle size 2.2 to 2.8 µm, apparent density 0.5 to 0.65 g /
cm ³ and a specific surface area of 0.68 m ² / g). Polyethylene: thermoplastic elastomer: paraffin wax = 5:
2: 3 (weight ratio), and 6 times the total weight of these nickel powders were kneaded in a mill at 150 ° C. for 15 minutes.

Next, the kneaded material was heated at 150 ° C. to a thickness of 0.7 mm.
Into a sheet with a hot press, and both sides are about 30μ thick
m of Ni foil electrode, and the Ni foil was thermocompression-bonded at 150 ° C. with a hot press machine to obtain a total thickness of 0.4 mm. This is diameter 1
It was punched out into a disc of cm to obtain an organic positive temperature coefficient thermistor element. FIG. 1 is a sectional view of the thermistor element.

The obtained device was placed in a thermostat at room temperature (25 ° C.).
From 120 ° C.) to 120 ° C., cooled at 2 ° C./min, and measured at a predetermined temperature by a four-terminal method. The initial room temperature resistance is 5.8 × 10 ⁻³ Ω, the resistance starts to increase at about 70 ° C., and the resistance change rate is 7 digits. It is confirmed that low room temperature resistance and large resistance change rate are compatible. Was done.

The device was heated at -40.degree.
A thermal shock test was performed at 5 ° C. for one cycle of 30 minutes.
After 15 cycles, the room temperature resistance was 1.8 × 10 ⁻² Ω and the change was slight.

A high-temperature high-humidity reliability test was performed under the conditions of 65 ° C. and 95% RH. The room temperature resistance after standing for 1000 hours was 6.4 × 10 ⁻³ Ω, and the change was slight.

[Example 2] Polystyrene (manufactured by Mitsubishi Chemical Corporation, trade name: HH102, MFR =
3.0g / 10min (200 ° C, 5kg load), density = 1.
05g / cm ³ ), styrene-based thermoplastic elastomer (trade name KRATON G1657, MF, manufactured by Shell Japan)
R = 9 g / 10 min (230 ° C., 2.16 kg load), density = 0.900 g / cm ³ , paraffin wax as a low molecular weight organic compound (Nippon Seisaku, HNP-10, melting point 75)
° C), and filamentous nickel powder (manufactured by INCO, trade name Type 255 nickel powder, average particle size 2.2 to 2.8 µm, apparent density 0.5 to 0.5) as conductive particles.
0.65 g / cm ³ and a specific surface area of 0.68 m ² / g). Polystyrene: thermoplastic elastomer: paraffin wax = 2: 4: 4 (weight ratio), and 6 times the total weight of these powders and nickel powder were kneaded in a mill at 150 ° C for 15 minutes.

The kneaded material was formed into a thermistor element at a molding temperature of 150 ° C. in the same manner as in Example 1.

The initial room temperature resistance was 4.5 × 10 ⁻³ Ω, 70
The resistance began to increase at around ° C., and a resistance change rate of 10 digits was obtained.

The device was subjected to a thermal shock test in the same manner as in Example 1. As a result, the room temperature resistance after 50 cycles was 1.9 × 10 ⁻² Ω, and the change was slight.

When a high-temperature high-humidity reliability test was performed in the same manner as in Example 1, the room temperature resistance after standing for 1000 hours was 5.4 × 10 ⁻³ Ω, and the change was slight.

Example 3 As a thermosetting polymer, 100 g of a pisphenol A type epoxy resin (Yuka Kasper Epoxy Co., Ltd., trade name: Evicoat 801) and a modified amine-based curing agent (Yuka Kasushi Evoxy Co., trade name: Epomate BOO)
2) 50 g, olefin-based thermoplastic elastomer (Mitsui Petrochemical, trade name: Mirastomer 6030N, MFR = 50 g / 10 min (230)
, 10 kg load), paraffin wax (HNP-10, melting point 75 ° C, manufactured by Nippon Seisaku) as a low molecular weight organic compound 7
59, filamentous nickel powder (manufactured by INCO, trade name Type 255 nickel powder, average particle size 2.2 to 2.8 μm, apparent density 0.5 to 0.5) as conductive particles
0.65 g / cm ³ and a specific surface area of 0.68 m ² / g). 20 g of a bisphenol A type epoxy resin, 10 g of a modified amine-based curing agent, 8 g of an olefin-based thermoplastic elastomer, 12 g of paraffin wax, and 30 ml of toluene were mixed by a centrifugal disperser for 10 minutes.

The obtained mixture in the form of a paint was coated to a thickness of about 30 μm.
m, applied to one side of a Ni foil electrode, sandwiched between the other electrodes, and further applied with a spacer to a thickness of 0.4 mm.
8 mm when sandwiched between brass plates and pressed with a hot press
The composition was cured by heating at 0 ° C. for 3 hours. The sheet-shaped cured product on which the electrode was thermocompression-bonded was punched into a disk having a diameter of 1 cm to obtain an organic substance positive temperature coefficient thermistor element.

The initial room temperature resistance was 7.2 × 10 ⁻³ Ω, 70
The resistance started to increase at around ° C, and a resistance change rate of 7 digits was obtained.

The device was subjected to a thermal shock test in the same manner as in Example 1. As a result, the room temperature resistance value after 50 cycles was 1.7 × 10 ⁻² Ω and the change was slight.

A high-temperature and high-humidity reliability test similar to that of Example 1 was performed. As a result, the room temperature resistance after standing for 1000 hours was 8.3 × 10 ⁻³ Ω, and the change was slight.

Example 4 As a polymer matrix, a linear low-density polyethylene (manufactured by Nippon Polychem, trade name UJ)
960, MFR = 5.0 g / 10 min (190 ° C., 2.1
6 kg load), density = 0.935 g / cm ³ , melting point 135
° C), an olefin-based thermoplastic elastomer (Mitsui Petrochemical, trade name: Mirastomer M4800N, MFR = 25)
g / 10min (230 ° C, 2.16kg load), density = 0.
890 g / cm ³ , melting point 165 ° C.) Paraffin wax (Baker Petrolite, Pol
yWax500, melting point: 88 ° C., filamentous nickel powder (manufactured by INCO, trade name: Ty) as conductive particles
pe210 nickel powder, average particle size 0.5-1.0μ
m, apparent density 0.8 g / cm ^3, specific surface area 1.5 to 2.5
m ² / g). Polyethylene: thermoplastic elastomer: paraffin wax = 6: 2: 2 (weight ratio),
Six times the total weight of these nickel powders and 15
Kneaded at 0 ° C. for 30 minutes.

The kneaded product was a thermistor element at a molding temperature of 150 ° C. in the same manner as in Example 1. Initial room temperature resistance is 3.8 ×
The resistance began to increase at around 10 ⁻³ Ω and 85 ° C., and a six-digit resistance change rate was obtained.

The device was subjected to a thermal shock test in the same manner as in Example 1. As a result, the room temperature resistance after 100 cycles was 5.0 × 10 ⁻³ Ω, and there was almost no change.

When a high-temperature and high-humidity reliability test was performed in the same manner as in Example 1, the room temperature resistance after standing for 1000 hours was 5.4 × 10 ⁻³ Ω, and there was almost no change.

Comparative Example 1 As a comparison, an element was made of a material containing no thermoplastic elastomer. High-density polyethylene [manufactured by Nippon Polychem, trade name HY540, MFR = 1.0 g / 10 min (190
° C, 2.16 kg), melting point 135 ° C] and low density polyethylene [manufactured by Nippon Polychem, trade name LC500, MFR =
4.0g / 10min (190 ° C, 2.16kg), melting point 10
6 ° C.], paraffin wax (HNP-10, manufactured by Nippon Seiro, melting point 75 ° C.) as a low molecular weight organic compound, filamentary nickel powder (InNCO Corporation, trade name Type 255 nickel powder, average particle size) as conductive particles. 2-2.8 μm, apparent density 0.5-0.65 g / c
m ³ , specific surface area 0.68 m ² / g). High density polyethylene: Low density polyethylene: Paraffin wax =
4: 1: 5 (weight ratio), and 6 times the total weight of these nickel powders were kneaded in a mill at 150 ° C. for 30 minutes.

The initial room temperature resistance was 1.7 × 10 ⁻³ Ω, 7
The resistance rapidly increased around 5 ° C., and a resistance change rate of 11 digits or more was obtained.

The device was subjected to a thermal shock test in the same manner as in Example 1. As a result, even after 10 cycles, the room mixed resistance value was 1. O × 10 ⁷ Ω or more, and a large increase in resistance was observed.

A high-temperature and high-humidity reliability test similar to that in Example 1 was performed. With O × 10 ⁴ Ω, the resistance value increased significantly as in the thermal shock test.

From the result of this comparison, it was found that the effect of the present invention was very large.

[0116]

As described above, according to the present invention, the reliability of the organic positive temperature coefficient thermistor can be improved, and the stability of the characteristics can be improved.

[Brief description of the drawings]

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

[Brief description of reference numerals]

 2 Thermistor body 3 Electrode

Continued on the front page F-term (reference) 4J002 AA00X AA01W AB01X AC11W BB00X BB06X BB07X BB08X BB15W BB23X BC03X BD00X BD14X BF03X BG10X BP01W BP03W CB00X CC00X CD00X CF21E CH01X CP00X0

Claims (6)

[Claims] 1. An organic positive temperature coefficient thermistor comprising a matrix composed of at least two or more polymer compounds, a low molecular organic compound, and conductive particles having spike-like projections, wherein said polymer matrix contains a thermoplastic elastomer. 2. The organic positive temperature coefficient thermistor according to claim 1, wherein said thermoplastic elastomer is contained in an amount of 2 to 60% by mass based on the whole matrix. 3. The organic positive temperature coefficient thermistor according to claim 1, wherein the low molecular weight organic compound has a melting point of 40 ° C. to 200 ° C. 4. The organic positive temperature coefficient thermistor according to claim 1, wherein said conductive particles having spike-like projections are connected in a chain. 5. The organic positive temperature coefficient thermistor according to claim 1, wherein said low molecular weight organic compound is segregated in a polymer matrix. 6. The device according to claim 1, which is a transferable circuit element for a secondary battery.
5. The organic positive temperature coefficient thermistor according to any one of to 5.