CN1179369C - Organic positive temp. coefficient thermal resistance - Google Patents
Organic positive temp. coefficient thermal resistance Download PDFInfo
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- CN1179369C CN1179369C CNB99120767XA CN99120767A CN1179369C CN 1179369 C CN1179369 C CN 1179369C CN B99120767X A CNB99120767X A CN B99120767XA CN 99120767 A CN99120767 A CN 99120767A CN 1179369 C CN1179369 C CN 1179369C
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Abstract
To realize characteristic of large rate of change or resistance and small hysteresis and enable easy operational temperature adjustment, by including thermosetting high molecular matrix, low molecular organic compound and conductive particles having spike-shaped protrusions. Epoxy resin, silicon resin, etc., in which oligomer with reactive epoxy group at terminal, is bridged with various kinds of hardener are used as a thermosetting high molecular matrix. Paraffin wax whose melting point is 40-100 deg.C, vegetable wax, animal wax, fats and oils, etc., are used as low molecular organic compound. Weight of conductive particles having spike-shaped protrusions is 1.5-5 times the total weight of the thermosetting high molecular matrix and the low molecular organic compound. The conductive particles are composed of primary particles having the respective sharp protrusions. A plurality of conical spike protrusions, whose heights are 1/3-1/50 of the particle diameter, exist in one particle. Metal, especially Ni, is suitable as the material. As a result, room temperature resistance is sufficiently low, the rate of change of resistance at on-operation time and off-operation time is large, and hysteresis of temperature-resistance curve is made small.
Description
The present invention relates to organic positive temp. coefficient thermistor, and described thermistor have PTC (the positive temperature coefficient of resistance) characteristic or performance that its resistance value increases with the increase of temperature as temperature sensor and overflow protecting element.
The organic positive temp. coefficient thermistor that has the conductive particle that is dispersed in the crystallization thermoplastic polymer is known in the prior art, as at US3, and 243,753 and 3,351, disclosed in 882.The increase of resistance value be considered to since when fusion crystalline polymer expansion caused, this will make the formed conductive channel of conductive fine particle split again.
The organic positive temp. coefficient thermistor can be used as the automatic control heater, overflow protecting element, and temperature sensor.Requirement to these purposes is: at non-operating state, under room temperature, resistance value is quite low, and the rate of change between the resistance value when resistance value when room temperature and operation is quite big, and the change of resistance value will reduce when repetitive operation.
For satisfying these requirements, advised using low molecular weight organic compound such as wax, and polymer thermoplastic matrix has been used as adhesive.Described organic positive temp. coefficient thermistor for example comprises: polyisobutene/paraffin/carbon black system (F.Bueche, J.Appl.Phys.,
44, 532,1973), butadiene-styrene rubber/paraffin/carbon black system (F.Bueche, the J. polymer science,
11, 1319,1973), and low density polyethylene (LDPE)/paraffin/carbon black system (people such as K.Ohe, Jpn.J.Appl.Phys.,
10, 99,1971).The automatic control heater that comprises the organic positive temp. coefficient thermistor that uses low molecular weight organic compound, current limiting elements etc. are disclosed in JP-B 62-16523,7-109786 and 7-48396, and JP-A62-51184,62-51185,62-51186,62-51187,1-231284,3-132001,9-27383 and 9-69410.In these cases, the increase of resistance value it is believed that it is because the fusion of low-molecular-weight organic compound causes.
Use an advantage of low-molecular-weight organic compound to be: because its degree of crystallinity of low-molecular-weight organic compound is usually above polymer, therefore, resistance value will sharply increase when temperature increases.Because polymer is easy to enter supercooled state, therefore, it will demonstrate hysteresis, wherein, and the temperature the when temperature when reducing resistance with the reduction of temperature is usually less than increase with temperature and increases resistance.When using low-molecular-weight organic compound, can make this hysteresis remain on less state.By using the low-molecular-weight organic compound of different melting points, the temperature (working temperature) when easily controlling resistance increases.Depend on different molecular weight and degree of crystallinity, and with the co-polymerization of monomer, polymer will be responsive to the change of fusing point, this will cause the change of crystalline state.In this case, usually can not get sufficient ptc characteristics.
Yet, in the organic positive temp. coefficient thermistor of in above-mentioned publication, listing, the compromise proposal that between low initial (room temperature) resistance and big resistance change rate, does not gear to actual circumstances.Jpn.J.Appl.Phys.,
10, 99,1971 show wherein, and resistivity (Ω cm) is increased to 10
8Example doubly.Yet the resistivity when room temperature is up to 10
4Therefore Ω cm, is out of use for overflow protecting element or temperature sensor particularly.Other application shows resistance value (Ω) or resistivity (Ω cm) at 10 times or lower and about 10
4Increase doubly, wherein room temperature resistance does not reduce fully.
Utilize a problem of the thermoplastic polymer that is used as matrix to be: because matrix is with fusion and fluidisation when melting point polymer, therefore, particularly at high temperature the dispersity of this system will change, and this will cause unsettled performance.
On the other hand, JP-A 2-156502,2-230684,3-132001 and 3-205777 have disclosed the organic positive temp. coefficient thermistor that uses low-molecular-weight organic compound and play the thermosetting polymer of matrix effect.Yet because carbon black and graphite are used as conductive particle, therefore, the changes in resistance rate is little of an order of magnitude or lower, and not fully reduction of room temperature resistance, or is about 1 Ω cm.Therefore, between low initial resistance and big resistance change rate, there is not compromise proposal.
JP-A 55-68075,58-34901,63-170902,2-33881,9-9482 and 10-4002, and US4,966,729 have proposed a kind of organic positive temp. coefficient thermistor, and it is made up of thermosetting polymer and conductive particle fully, wherein do not rely on low-molecular-weight organic compound.In these thermistors since with carbon black and graphite as conductive particle, therefore, between the room temperature resistance of 0.1 Ω cm at the most and 5 orders of magnitude or bigger big resistance change rate, do not have compromise proposal at all.Usually; the thermistor system of having only thermosetting polymer and conductive particle to form does not have tangible fusing point; therefore great majority increase displays temperature in these resistance to the blunt resistance of resistive performance; particularly, can not provide satisfactory performance in the application such as temperature sensor at overflow protecting element.
In many cases, in comprising above-mentioned publication, in the organic positive temp. coefficient thermistor of listed prior art, carbon black and graphite are used as conductive particle.Yet, utilize a problem of carbon black to be: when using the amounts of carbon black that increases to reduce initial resistance value, will obtain inadequate resistance change rate; And between low initial resistance and big resistance change rate, there is not rational compromise proposal.Sometimes, usually metallic particles is used as conductive particle.In this case, between low initial resistance and big resistance change rate, there is not rational compromise proposal equally.
A kind of method that addresses this problem is disclosed among the JP-A5-47503, this patent application instruction: use the conductive particle that has sharp projection.More particularly, it has disclosed: polyvinylidene fluoride is used as sharp conductive particle as crystalline polymer and with the sheet nickel by powder.US5,378,407 have also disclosed and have a kind ofly comprised the filament nickel that has sharp projection, and polyolefin, the thermistor of olefin copolymer or fluoropolymer.Yet these thermistors are still not enough aspect hysteresis, therefore, although improved compromise proposal between low initial resistance and the big resistance change rate, but still are not suitable for for example temperature sensor.This is because there is not low-molecular-weight organic compound to be used as the cause of operation material or active material.Utilize another problem of these thermistors to be: when further heating after resistance increases when in work, they will demonstrate resistance value increases NTC (negative temperature coefficient of the resistance) performance that reduces with temperature.Be pointed out that above-mentioned publication does not advise using low-molecular-weight organic compound at all.
JP-A5-198403 and 5-198404 have disclosed a kind of thermosetting resin and have the organic positive temp. coefficient thermistor of sharp projection conductive particle mixture of comprising, and have demonstrated the resistance change rate greater than 9 orders of magnitude.Yet, when reducing room temperature resistance value, will obtain inadequate resistance change rate by the increase amount of filler.Therefore, be difficult to realize compromise proposal between low initial resistance value and the big resistance change rate.In addition, because thermistor is made up of thermosetting resin and conductive particle, therefore, it will not have tangible resistance sharply to increase.Above-mentioned publication does not relate to the use low molecular compound yet.
The purpose of this invention is to provide a kind of organic positive temp. coefficient thermistor, this thermistor has enough low resistance in room temperature, and big resistance change rate in working order and between the non operating state, and can carry out work under to the hysteresis of resistance curve in low temperature, after increasing, resistance do not have the NTC phenomenon, working temperature is easy to control, and has high stability.
Described purpose is achieved by the present invention as described below.
(1) a kind of organic positive temp. coefficient thermistor comprises thermoset polymer matrix, low-molecular-weight organic compound and conductive particle, the slightly pointed projection of the equal tool of each particle.
(2) according to the organic positive temp. coefficient thermistor of (1), the fusing point of wherein said low-molecular-weight organic compound is 40-200 ℃.
(3) according to the organic positive temp. coefficient thermistor of (1), the molecular weight of wherein said low-molecular-weight organic compound is 4,000 or lower.
(4) according to the organic positive temp. coefficient thermistor of (1), wherein said low-molecular-weight organic compound is pertroleum wax or aliphatic acid.
(5) according to the organic positive temp. coefficient thermistor of (1), wherein said thermoset polymer matrix is: epoxy resin, unsaturated polyester resin, polyimides, polyurethane, any of phenol resin and silicone resin.
(6) according to the organic positive temp. coefficient thermistor of (1), the weight of wherein said low-molecular-weight organic compound is 0.2-2.5 times of described thermoset polymer matrix weight.
(7) according to the organic positive temp. coefficient thermistor of (1), wherein said conductive particle is chain and interconnects, wherein the slightly pointed projection of the equal tool of each particle.
In the present invention, the pointed projection on conductive particle makes tunnel current can easily pass through thermistor, and makes it to obtain the lower initial resistance of initial resistance that Billy obtains with the spheroidal conductive particle.When thermistor is in running order,, the space between the pointed conductive particle changes because, therefore can obtaining big resistance greater than the space between the spheroidal conductive particle.
In the present invention, low-molecular-weight organic compound is mixed in the thermistor, the result is by the fusion of low-molecular-weight organic compound, to have obtained the PTC that resistance value increases with temperature (the positive temperature coefficient of resistance) performance.Therefore, temperature is to the curve hysteresis of resistance, compares with the hysteresis that fusion by crystallization thermoplastic polymer obtains, and will have greatly and reduce.Low-molecular-weight organic compounds by using different melting points etc. are to the control of working temperature, and the Control work temperature is more easy with the change of melting point polymer with Billy.With thermosetting polymer is different as the thermistor of operation material or active material, thermistor of the present invention will demonstrate the rapid increase of resistance in use.
In addition, the present invention is used as matrix with thermosetting polymer.When thermistor of the present invention is come into operation,, obtained big resistance and changed by using big expanding volume and the low-molecular-weight organic compound of fusion easily taking place.Yet, because the melt viscosity of low-molecular-weight organic compound is low, so when work, only the element of being made up of low-molecular-weight organic compound and conductive particle can not keep its shape.In order to prevent thermistor element fluidization owing to the low molecular weight organic compound that its fusion caused when working, or prevent the distortion of thermistor element when work, low-molecular-weight organic compound and conductive particle need be scattered in the matrix polymer.When thermoplastic polymer is used as described matrix polymer, because polymer in the temperature fusion of the fusing point that is higher than low-molecular-weight organic compound, therefore particularly the problem of relevant high-temperature stability will occur.According to the present invention, thermosetting polymer is used as polymeric matrix, thereby low-molecular-weight organic compound and conductive particle are scattered in the insoluble and not molten three dimensional matrix, described thermistor is improving aspect the stability, Billy is much better with the thermistor of thermoplastic polymer, therefore, thermistor of the present invention can keep low room temperature resistance, and keeps big resistance variations for a long time when work.
When the thermistor that utilizes polymer thermoplastic matrix heats, will find that wherein resistance value increases the NTC phenomenon that reduces with temperature after its resistance increases.In when cooling, thermistor has demonstrated the curve hysteresis of big temperature to resistance, and promptly resistance begins to reduce from the temperature greater than the fusing point of low-molecular-weight organic compound.Especially when thermistor is used as protection component, be higher than the temperature of predetermined temperature, thermistor recovers resistance value will become a serious problem.In addition, in the system of using thermoplastic resin and conductive particle, also found the NTC phenomenon.The reduction of resistance seemingly because: even after resistance increases, by the electric current by thermistor continuously, rearranging of conductive particle caused in the molten state matrix.The situation that the temperature of working temperature began to descend when resistance value heated from being higher than during for cooling, identical reason also is suitable for.According to the present invention, by using not molten and not molten thermoset polymer matrix, can eliminate above-mentioned problem basically, the NTC phenomenon that takes place after promptly (1) resistance increases, (2) temperature is to the curve hysteresis of resistance.
Fig. 1 is the sectional view of organic positive temp. coefficient thermistor.
Fig. 2 is according to the temperature of the thermistor element of embodiment 1 curve to resistance.
Fig. 3 is according to the temperature of the thermistor element of embodiment 2 curve to resistance.
Fig. 4 is according to the temperature of the thermistor of Comparative Examples 1 curve to resistance.
Organic posistor of the present invention comprises the thermosetting polymer matrix, and low molecule is organic Compound and with the conductive particle of sharp projection.
Preferably but not exclusively with epoxy resin, unsaturated polyester resin, polyimides, polyurethane, phenol tree Fat and silicone resin are as the thermosetting polymer matrix.
Epoxy resin makes the oligomer (molecule with the active epoxy end group by utilizing various curing agent Amount is from hundreds of to about 10,000) take place to solidify and make, and be divided into the glycidol that is represented by bisphenol-A Ether type, ethylene oxidic ester type, glycidyl amine type and alicyclic ring type. In some applications, can also make With trifunctional or polyfunctional epoxy resin. In these epoxy resin, preferably use glycidol ether Type epoxy resin, most preferably bisphenol A type epoxy resin. The epoxy resin that uses in the present invention, Its epoxide equivalent is preferably from about 100-500. Depend on related reaction mechanism, curing agent is divided into Polyaddition type, catalytic type and condensed type. Self will add to epoxide group or oh group the polyaddition type curing agent On, and comprise polyamine, acid anhydrides, poly-phenol, polymercaptan, isocyanic acid acid etc. Catalytic curing agent will The polymerization of catalysis epoxide group, and comprise tertiary amine, imidazoles etc. The condensed type curing agent will with hydroxyl Carry out condensation and solidify, and comprise phenol resin, melamine resin etc. In the present invention, preferably with addition polymerization Type curing agent, especially polyamine curing agent and anhydride curing agent are as the curing of bisphenol A type epoxy resin Agent. Condition of cure can carry out suitable determining.
Described epoxy resin and curing agent are commercially available, for example comprise: Epicoat (resin) and Epicure and Epomate (curing agent), all these materials have by Yuka Shell Epoxy Limit company makes, and the Araldite that is made by Ciba-Geigy.
Unsaturated polyester resin comprises: mainly be made up of unsaturated dibasic acid or binary acid and polyalcohol Polyester (molecular weight about 1,000-5,000) and polyester are dissolved in cross-linked ethylene monomer wherein. Then, Organic peroxide such as benzoyl peroxide are used as polymerization initiator, this solution is solidified. For Be cured, can use polymerization accelerant if need. As the unsaturated polyester that uses among the present invention The ester raw material preferably is used as unsaturated dibasic acid with maleic anhydride and fumaric acid anhydride; Preferably with phthalic acid Acid anhydride, isophthalic acid acid anhydride and terephthalic acids acid anhydride are used as diacid, and preferably are used as propane diols and ethylene glycol many Unit's alcohol. Preferably with styrene, diallyl p phthalate and vinyltoluene are as vinyl monomer. The consumption of vinyl monomer can suitably be determined. Yet, usually preferably, the vinyl list The consumption of body is every mole of about 1.0-3.0 mole of fumaric acid residue. For stoping the glue in the building-up process Solidifying effect and control curing performance can use known polymerization initiator, such as quinones and quinhydrones class. Condition of cure can suitably be determined.
Described unsaturated polyester resin is the commercially available prod, for example comprises: had by Nippon Shokubai The Epolac that limit company makes, the Polyset that is made by Hitachi Kasei Co., Ltd and by Dainippon Ink﹠Chemicals, Inc., the Polylight of manufacturing.
Depend on the preparation method, usually polyimides is divided into condensed type and polyaddition type. Yet, at this In the invention, preferably the span with the polyaddition type polyimides comes acyl hypotype polyimides. By using all Polymerization is namely with the reaction of other unsaturated bond, with the Mi Xieer addition reaction of aromatic amine, with two The Di Ersi of alkene-A Deer addition reactions etc. can make BMI type polyimide curing. Particularly preferably be, by the addition reaction between BMI and the aromatic diamine obtain two The maleimide polyimide type resin. Aromatic diamine comprises: diaminodiphenyl-methane etc. Synthetic Can suitably determine with condition of cure.
Described polyimides can obtain from the market, for example comprises: chemistry Co., Ltd of Toshiba makes Imidaloy and the Kerimide that is made by Ciba-Geigy.
Polyurethane obtains by the sudden reaction between PIC and the polyol. To gather Isocyanates is divided into aromatics type and aliphatic type, wherein aromatics type preferably. Preferably, two isocyanides Acid 2,4-or 2,6-toluene ester, two isocyanic acid diphenyl methyl esters, naphthalene diisocyanate etc. Polyhydroxylated Compound comprises: polyether polyol, and such as polypropylene glycol, polyester polyol, the many alcohol of acryloyl group etc., wherein excellent Select polypropylene glycol. The catalyst that uses in the present invention can be amine type catalyst (tertiary amine catalyst as Triethylenediamine and amine salt catalyst). Yet, for this, preferably use the organic metal type to urge Change agent, such as dibutyl tin laurate, and stannous octoate. In addition, catalyst can also with auxiliary agent as Crosslinking agent, for example polyalcohol and polyamine are used in combination. Synthetic and condition of cure can suitably advance Row is determined.
Described polyurethane resin can obtain from the market, for example comprises: by Sumitomo Bayer The Sumijule that Polyurethane Co., Ltd makes is by Mitsui Toatsu chemical company system The NP series of making, and the Colonate that is made by Nippon polyurethane Co., Ltd.
Phenol resin obtains by the reaction of phenol and aldehyde such as formaldehyde, and, depend on synthesis condition, Usually be divided into phenolic varnish type and resol type. If with crosslinking agent such as hexa Together heating, the phenolic varnish type phenol resin that forms under acid catalyst so will solidify, and by adding Heat or in the presence of acidic catalyst, the resol type phenol that forms under base catalyst is set Fat self will solidify. These two kinds of resins all can be used for the present invention. Synthetic and condition of cure can be fitted The locality is determined.
Described phenol resin can obtain from the market, for example comprises: had by Sumitomo Bakelite The Sumicon that limit company makes, by the Standlite of Hitachi Kasei Co., Ltd manufacturing, And the Tecolite that is made by Toshiba chemistry Co., Ltd.
Silicone resin comprises: the siloxane bond of repetition for example comprises: mainly by organic halo silicon The hydrolysis of oxygen alkane or polycondensation and the silicone resin that obtains; Or by alkyd varnish, polyester, acrylic acid, Epoxides, phenol, the silicone resin of urethanes and melamine modification; Poly-by linearity Dimethyl siloxane or its copolymer and organic peroxide etc. crosslinked and the silicon rubber that obtains; And Condensed type or the polyvinyl siloxane of room temperature vulcanization (RTV).
Described silicone resin can obtain from market, for example comprises: by Shin-Etsu chemistry Co., Ltd, various silicon rubber and various silicone resin that Toray Dow Corning Co., Ltd and Toshiba Silicone Co., Ltd make.
The thermosetting resin of Shi Yonging can suitably be selected according to the purposes of desirable performance of thermistor and thermistor in the present invention.Particularly preferably be, use epoxy resin and unsaturated polyester resin.Two or more resins can be aggregated into polymer together.
Although polymeric matrix is preferred only by above-mentioned described thermosetting resin, in some cases, also can add elastomer and/or thermoplastic resin therein.
Preferably but exclusive be not, the low-molecular-weight organic compound that uses in the present invention still is crystalline solid material when normal temperature or about 25 ℃, and molecular weight is about at the most 4,000, and is preferably about at the most 1,000, more preferably from 200-800.
Described low-molecular-weight organic compound for example comprises: paraffin (for example pertroleum wax such as paraffin and microwax, and native paraffin such as vegetable wax, animal wax and mineral wax), and fat and oil (for example fat, and those materials that are called hard fat).Paraffin, and the actual composition of fat and oil can be hydrocarbon (for example contains 22 or the alkane type straight-chain hydrocarbons of more a plurality of carbon atoms), aliphatic acid (for example contain 12 or the aliphatic acid of the alkane type straight-chain hydrocarbons of more a plurality of carbon atoms), fatty acid ester (for example, by contain 20 or the methyl esters of the unrighted acid that obtains of the unrighted acid of more a plurality of carbon atoms and lower alcohol such as methyl alcohol), fatty acid amide (for example, the acid amides of unsaturated fat acid amides, as oleamide and mustard acid amides), aliphatic amine (for example, contain 16 or the aliphatic primary amine of more a plurality of carbon atoms), higher alcohol (for example contain 16 or the alphanol of more a plurality of carbon atoms), and chlorinated paraffin wax.Yet itself can use these compositions, or can be used in combination with low-molecular-weight organic compound.The low-molecular-weight organic compound that uses among preferred reply the present invention is selected, and to cause when considering polymeric matrix polarity, described component is well disperseed together.With regard to low-molecular-weight organic compound, preferably pertroleum wax and aliphatic acid.
These low-molecular-weight organic compounds can obtain from market, and can use the commercially available prod immediately.
In the present invention, one of them purpose provides: preferably can be lower than 200 ℃, especially can be lower than the thermistor of working under 100 ℃ the temperature; Its fusing point of employed low-molecular-weight organic compound (mp) is preferably from 40-200 ℃, more preferably from 40-100 ℃.Described low-molecular-weight organic compound for example comprises: paraffin (lignocerane C for example
24H
50, mp49-52 ℃; Hexatriacontane C
36H
74, mp73 ℃; HNP-10, mp75 ℃, Nippon Seiro Co., Ltd; And HNP-3, mp66 ℃, NipponSeiro Co., Ltd), microwax (for example, Hi-Mic-1080, mp83 ℃, Nippon Seiro Co., Ltd; Hi-Mic-1045, mp70 ℃, Nippon Seiro Co., Ltd; Hi-Mic-2045, mp64 ℃, Nippon Seiro Co., Ltd; Hi-Mic-3090, mp89 ℃, Nippon Seiro Co., Ltd; Seratta 104, and mp96 ℃, Nippon Sekiyu Seisei Co., Ltd; With 155 Microwax, mp70 ℃, Nippon Sekiyu Seisei Co., Ltd), aliphatic acid (for example, behenic acid, mp81 ℃, Nippon Seika Co., Ltd; Stearic acid, mp72 ℃, Nippon Seika Co., Ltd; And palmitic acid, mp64 ℃, Nippon Seika Co., Ltd), fatty acid ester (arachidic acid methyl ester, mp48 ℃, Tokyo Kasei Co., Ltd), and fatty acid amide (for example, oleamide, mp76 ℃, Nippon Seika Co., Ltd).Also operablely in addition be: Tissuemat E (for example, Mitsui High-Wax110 by the manufacturing of Mitsui petro chemical industry company, mp100 ℃), stearmide (mp109 ℃), two lauramides (mp111 ℃), N-N '-ethylidene-bimonthly osmanthus acid amides (mp157 ℃), N-N '-two oil base adipamide (mp119 ℃) and N-N '-hexa-methylene-two-12-hydroxyl stearmide (mp140 ℃).In addition, can also use the wax mixture that comprises paraffin and resin, and can comprise microwax, and the fusing point of described mixture is from 40-200 ℃.
Low-molecular-weight organic compound can use separately, or two or more are used in combination, and this will depend on working temperature etc.
The weight of the low-molecular-weight organic compound that uses among the present invention is 0.2-4 times of described thermoset polymer matrix (comprising curing agent etc.) weight, and more preferably 0.2-2.5 doubly.When this mixing ratio becomes the consumption of lower or low-molecular-weight organic compound when becoming still less, will obtain inadequate resistance change rate.On the contrary, when the become consumption of bigger or low-molecular-weight organic compound of this mixing ratio becomes more for a long time, not only big distortion will take place in thermistor element when the low-molecular-weight organic compound fusion, and, also be difficult to low-molecular-weight organic compound is mixed with conductive particle.
Each free sharp primary particle of the conductive particle of Shi Yonging (all slightly pointed projection of each particle) is formed in the present invention.More particularly, the projection of many (10-500 usually) circular cones and point is arranged on single particle, the height of each projection is 1/3 to 1/50 of a particle diameter.Conductive particle is preferably made by nickel etc.
Although described conductive particle can use by discontinuous powder type, preferably, with about 10-1, the form of the chain of 000 interconnective primary particle is used, so that form secondary.The interconnective primary particle of chain form can partly include primary particle.The example of shaping thing comprises: the nickel by powder that has sharp projection of spheroidal, and one of them can obtain from the market, and commodity are called INCO 123 type nickel by powder (INCO Co., Ltd).The average grain diameter of these powder is from about 3-7 micron, and apparent density is from about 1.8-2.7g/cm
3, specific area is approximately from 0.34-0.44m
2/ g.
The preferred example of the latter is a filament shape nickel by powder, some of them can obtain from the market, its commodity are by name: INCO 255 type nickel by powder, INCO 270 type nickel by powder, INCO 287 type nickel by powder and INCO 210 type nickel by powder, all these powder are made by INCO Co., Ltd, and wherein second kind of shaping thing is preferred.Preferably at least 0.1 micron of the average grain diameter of primary particle is more preferably from about 0.5 to about 4.0 microns.The primary particle of from 1.0 to 4.0 microns of average grain diameters most preferably, and can mix from 0.1 to the primary particle less than 1.0 microns with 50% weight or average grain diameter still less.Apparent density is from about 0.3-1.0g/cm
3, specific area is from about 0.4-2.5m
2/ g.
This is to be noted that average grain diameter measures by Fischer subsieve method.
Described conductive particle is listed in JP-A5-47503 and US5, in 378,407.
Except that the conductive particle that has sharp projection, can also use the carbonaceous conductive particle, as carbon black, graphite, carbon fiber, metallization carbon black, Graphon and metallized carbon fiber, spheroidal, flakelike powder shape or fibrous metal particle, scribble the metallic particles (for example, the nickel particle of silver coating) of different metal, ceramic conductive particle, as tungsten carbide, titanium nitride, zirconium nitride, titanium carbide, the particle that titanium boride and molybdenum silicide are such, and be disclosed in conduction potassium titanate crystal whisker among JP-A8-31554 and the 9-27383.The consumption of described conductive particle preferably is at most: the sharp conductive particle of 25% weight.
The weight of the conductive particle of Shi Yonging in the present invention, the 1.5-5 that is preferably thermoset polymer matrix and low-molecular-weight organic compound total weight (total weight of organic component comprises curing agent etc.) doubly.When this mixing ratio becomes the consumption of lower or conductive particle still less the time, can not make the room temperature resistance of the thermistor of non operating state become enough low.On the contrary, when this mixing ratio become higher or conductive particle consumption more for a long time, not only be difficult to obtain big resistance change rate, and be difficult to obtain uniform mixing, this can not obtain any stable performance.
Below, will explain how to make organic positive temp. coefficient thermistor of the present invention.
With the thermosetting resin (not through solidifying) of specified rate, curing agent or analog, low-molecular-weight organic compound and sharp conductive particle mix together and disperse, so that obtain the mixture of coating shape.Can utilize various blenders, disperser, grinder, roll coaters etc. mix and disperse with known method.If bubble is introduced in this mixture, so, this mixture will foam under vacuum.For carrying out viscosity control, can use all kinds of solvents such as aromatic hydrocarbon solvent, ketone and alcohol.This mixture is curtain coating between nickel, copper or other metal foil electrode, or is coated with described electrode by silk screen printing etc. with mixture, thereby obtains a sheet material.Under the given heat-treat condition of thermosetting resin, sheet material is cured.At this moment, thermosetting resin can be cured at high temperature then in precuring under the relative low temperature.In addition, mixture can be solidified into sheet-form separately, then conductive paste or analog be applied on it, so that on sheet material, form electrode.Finally, resulting stamped from sheetstock is become desirable shape, thereby obtain thermistor element.
Organic thermistor of the present invention can comprise various additives, and precondition is that these additives can not damage the performance that the present invention is scheduled to.For preventing the thermal decomposition of polymeric matrix and low-molecular-weight organic compound, for example, also antioxidant can be mixed in the thermistor element.Can be with phenol, organic sulfur, phosphites (based on organophosphor) etc. are as antioxidant.
In addition, thermistor of the present invention can also comprise: as good heat conduction and conductive additive, and the silicon nitride of in JP-A57-12061, describing, silicon dioxide, aluminium oxide and clay (mica, talcum etc.), the silicon of in JP-B7-77161, describing, carborundum, silicon nitride, beryllium oxide and selenium, inorganic nitride of in JP-A5-217711, describing and magnesium oxide, etc.
For improving durability, thermistor of the present invention can comprise: the titanium oxide of describing in JP-A5-226112, iron oxide, zinc oxide, silicon dioxide, magnesium oxide, aluminium oxide, chromium oxide, barium sulfate, calcium carbonate, calcium hydroxide and lead oxide; The inoganic solids of the high relative dielectric constant of in JP-A6-68963, describing, barium titanate for example, strontium titanates, etc.
For improving withstand voltage properties, thermistor of the present invention can comprise: the boron carbide of describing among the JP-A4-74383, etc.
For improving intensity, thermistor of the present invention can comprise: the hydrated alkali metal titanate of describing among the JP-A5-74603, and the titanium oxide of describing among the JP-A8-17563, iron oxide, zinc oxide and silicon dioxide, etc.
As crystallization nucleating agent, thermistor of the present invention can comprise: alkali halide of describing among the JP-B59-10553 and melamine resin, the benzoic acid of describing among the JP-A6-76511, dibenzyl sorbitol and metal benzoate salt, the talcum of in JP-A6-6864, describing, zeolite and dibenzyl sorbitol, the glucitol derivative of describing among the JP-A7-263127 (gelling agent), pitch and two (4-tert-butyl-phenyl) sodium phosphate, or the like.
As the electric arc controlling agent, thermistor of the present invention can comprise: aluminium oxide of in JP-B4-28744, describing and magnesium oxide hydrate, and metal hydrate of in JP-A61-250058, describing and carborundum, or the like.
As the prophylactic of metal illeffects, thermistor of the present invention can comprise: the Irganox MD1024 (Ciba-Geigy) that in JP-A7-6864, describes, or the like.
As fire retardant, thermistor of the present invention can comprise: antimonous oxide of describing in JP-A61-239581 and aluminium hydroxide, the magnesium hydroxide of in JP-A5-74603, describing, halogen-containing organic compound (comprising polymer), as 2, two (4-hydroxyl-3,5-dibromo phenyl) propane of 2-and polyvinylidene fluoride (PVDF), phosphorus compound such as ammonium phosphate, or the like.
Except that these additives, thermistor of the present invention can also comprise: zinc sulphide, basic magnesium carbonate, aluminium oxide, calcium silicates, magnesium silicate, alumino-silicate clays (mica, talcum, kaolin, imvite etc.), glass dust, the sheet glass sprills, glass fibre, calcium sulfate, or the like.
The consumption of above-mentioned additive is at most: polymeric matrix, 25% of low-molecular-weight organic compound and conductive particle total weight.
Organic positive temp. coefficient thermistor of the present invention has low initial resistance in its non operating state, as the room temperature resistivity value representation by about 10-2 to 100; And resistance will sharply increase when work; Resistance change rate when its non operating state transits to its operating state is 6 orders of magnitude.
Embodiment
Below with reference to embodiment and Comparative Examples, the present invention is done to explain more specifically.
Embodiment 1
The amine hardener (Epomate B002 is by Yuka Shell Epoxy Co., Ltd) of bisphenol A type epoxy resin (Epicoat 801, by Yuka Shell Epoxy Co., Ltd) and modification is used as thermoset polymer matrix.Paraffin (HNP-10 is made by Nippon Seiro Co., Ltd, and fusing point is 75 ℃) is used as low-molecular-weight organic compound, and filament shape nickel by powder (255 type nickel by powder, INCO Co., Ltd makes) is used as conductive particle.The average grain diameter of conductive particle is from the 2.2-2.8 micron, and apparent density is from 0.5-0.65g/cm
3, specific area is 0.68m
2/ g.
In centrifugal disperser, with 20 gram bisphenol A type epoxy resins, the amine hardener of 10 gram modifications, 15 gram paraffin (epoxy resin and curing agent total weight 0.5 times), 180 gram nickel powders (organic component total weight 4 times) and 20ml toluene mixed about 10 minutes together.Resulting coating shape mixture is applied on the face of 30 micron thickness nickel foil electrodes, and another nickel foil electrode is placed on the mixture of coating.Utilize distance piece, pellet module is clipped between the copper coin, to obtain the gross thickness of 1mm.At 80 ℃ this assembly was carried out hot curing 3 hours, in hot press, suppress simultaneously.Electrode hot pressing to the pellet module on it that so solidifies is struck out the disk that diameter is 1cm, thereby obtain the organic positive temp. coefficient thermistor element.As from the Fig. 1 in thermistor element cross section as can be seen, thermistor element sheet material 12 promptly comprises low-molecular-weight organic compound, and the cured sheet of polymeric matrix and conductive particle is sandwiched between the nickel foil electrode 11.
In thermistor, this element is heated to 120 ℃ and reduce to room temperature from 120 ℃ from room temperature (25 ℃), the speed of heating and cooling is 2 ℃/minute, then, by four-hold-carrying, under given temperature resistance value is measured, and obtains the curve of temperature to resistance.The result maps in Fig. 2.
The initial room temperature of element (25 ℃) resistance value is 8.2 * 10
-3Ω (6.4 * 10
-2Ω cm), and 75 ℃ of resistance have a rapid increase near melting point of paraffin wax, and wherein resistance change rate is greater than 10 orders of magnitude.Even when continuation is heated to 120 ℃ with element after resistance increases, do not observe the decline (NTC phenomenon) of resistance.Find that when cooling, temperature is basic identical during with heating to the curve of resistance; Hysteresis significantly reduces.
Embodiment 2
With unsaturated polyester resin (G-110AL, make by Nippon Shokubai Co., Ltd) as thermoset polymer matrix, benzoyl peroxide (Kadox B-75W, by Kayaku, Akuzo Co., Ltd makes) as organic peroxide, behenic acid is (by Nippon, Seika Co., Ltd makes, fusing point is 81 ℃) as low-molecular-weight organic compound, the filament shape nickel powder (255 type nickel by powder, INCO Co., Ltd make) identical with embodiment 1 is as conductive particle.
With 30 gram unsaturated polyester resins, 0.3 gram benzoyl peroxide, 15 gram behenic acids, 180 gram nickel powders and 20ml toluene are mixed together about 10 minutes in centrifugal disperser.Resulting coating shape mixture is applied on the face of 30 micron thickness nickel foil electrodes, and another nickel foil electrode is placed on the mixture of coating.Utilize distance piece, pellet module is clipped between the copper coin, to obtain the gross thickness of 1mm.At 80 ℃ this assembly was carried out hot curing 30 minutes, in hot press, suppress simultaneously.Electrode hot pressing to the pellet module on it that so solidifies is struck out the disk that diameter is 1cm, thereby obtain the organic positive temp. coefficient thermistor element.Then, as described in embodiment, obtain the curve of the temperature of this element to resistance.The result maps in Fig. 3.
The initial room temperature of element (25 ℃) resistance value is 5.0 * 10
-3Ω (3.9 * 10
-2Ω cm), and near 81 ℃ or near the behenic acid fusing point, resistance has a rapid increase, and wherein resistance change rate is greater than 8 orders of magnitude.Even when continuation is heated to 120 ℃ with element after resistance increases, almost do not observe or do not observe the decline (NTC phenomenon) of resistance.Find that when cooling, temperature is basic identical during with heating to the curve of resistance; Hysteresis is enough to reduce about 10 ℃.By limiting, the degree of hysteresis is: poor before the work and between the defined working temperature of intersection point of the tangent line of afterwards temperature and resistance curve being done and the working temperature that similarly obtained by temperature and resistance curve when cooling off.
Embodiment 3
Make thermistor element as embodiment 1, different is, the amine type curing agent that replaces bisphenol A type epoxy resin and modification, with the poly-amino-two-maleimide prepolymer (KerimideB601 of 20 grams, make by Ciba-Geigy) and 10 gram dimethyl formamides be used as thermoset polymer matrix, curing is to carry out 1 hour and carried out 3 hours at 180 ℃ at 150 ℃.Find that by assessment this thermistor is equivalent to embodiment 1 resulting thermistor.
Embodiment 4
Make thermistor element as embodiment 1, different is to replace the amine type curing agent of bisphenol A type epoxy resin and modification, with 30 gram polyurethane (Colonate, make by Nippon Polyurethane Co., Ltd) as thermoset polymer matrix, be solidificated in 100 ℃ and carried out 1 hour.Find that by assessment this thermistor is equivalent to embodiment 1 resulting thermistor.
Embodiment 5
Make thermistor element as embodiment 1, different is to replace the amine type curing agent of bisphenol A type epoxy resin and modification, with 30 gram phenol resin (Sumicon PM, make by Sumitomo Bakelite Co., Ltd) as thermoset polymer matrix, be solidificated in 120 ℃ and carried out 3 hours.Find that by assessment this thermistor is equivalent to embodiment 1 resulting thermistor.
Embodiment 6
Make thermistor element as embodiment 1, different is to replace the amine type curing agent of bisphenol A type epoxy resin and modification, with 30 gram silicone resin (TSE3221, make by Toshiba Silicone Co., Ltd) as thermoset polymer matrix, be solidificated in 100 ℃ and carried out 1 hour.Find that by assessment this thermistor is equivalent to embodiment 1 resulting thermistor.
Comparative Examples 1
Make thermistor as embodiment 1, different is do not use paraffin, and the consumption of nickel powder to be 4 times of epoxy resin and curing agent total weight.Obtain the curve of the temperature of this element by embodiment 1 then to resistance.The result maps in Fig. 4.
The initial room temperature of this element (25 ℃) resistance is 8.8 * 10
-3Ω (6.9 * 10
-2Ω cm).Resistance does not have tangible transition temperature from about 80 ℃ of increases gradually.In addition, be 13 Ω 180 ℃ resistance values, resistance change rate is low to moderate 3.2 orders of magnitude.
Comparative Examples 2
Make thermistor element as embodiment 1, different is that (TokaBlack#4500 is made by Tokai Carbon Co., Ltd the conductive particle carbon black, and average grain diameter 60 nanometers, specific area are 66m
2/ g) consumption is an epoxy resin, curing agent and paraffin total weight 0.3 times.Assess by embodiment 1 then.
The initial room temperature of this element (25 ℃) resistance is 7.2 Ω (56.5 Ω cm).And resistance will increase near 75 ℃ or paraffin melting point, and resistance change rate is low to moderate 2.5 orders of magnitude.
Increase to 0.5 times of mixture weight by the consumption with carbon black, room temperature resistance value will reduce.Yet, will observe to the changes in resistance rate and will further descend.For this reason, the effect with sharp projection conductive particle will be tangible.
The invention effect
According to the present invention, so organic posistor can be provided, described thermistor has Very low room temperature resistance, and big resistance change rate in working order and between the off working state, and And can carry out work under to the resistance curve hysteresis in the temperature that reduces, after resistance increases, not have The NTC performance is easy to control operating temperature, and has high stability.
Claims (8)
1. organic positive temp. coefficient thermistor, comprise thermoset polymer matrix, molecular weight is 4,000 or lower low-molecular-weight organic compound and conductive particle, the slightly pointed projection of the equal tool of each particle, wherein the height of each sharp projection be described conductive particle particle diameter 1/3～1/50.
2. according to the organic positive temp. coefficient thermistor of claim 1, the fusing point of wherein said low-molecular-weight organic compound is 40-200 ℃.
3. according to the organic positive temp. coefficient thermistor of claim 1, the weight of wherein said conductive particle is 1.5～5 times of total weight of described thermoset polymer matrix and low-molecular-weight organic compound.
4. according to the organic positive temp. coefficient thermistor of claim 1, wherein said low-molecular-weight organic compound is pertroleum wax or aliphatic acid.
5. according to the organic positive temp. coefficient thermistor of claim 1, wherein said thermoset polymer matrix is: epoxy resin, unsaturated polyester resin, polyimides, polyurethane, any of phenol resin and silicone resin.
6. according to the organic positive temp. coefficient thermistor of claim 1, the weight of wherein said low-molecular-weight organic compound is 0.2-2.5 times of described thermoset polymer matrix weight.
7. according to the organic positive temp. coefficient thermistor of claim 1, wherein said conductive particle is chain and interconnects, wherein the slightly pointed projection of the equal tool of each particle.
8. according to the organic positive temp. coefficient thermistor of claim 1, its initial room-temperature resistance is 8.2 * 10
-3Below the Ω, resistance change rate is 8 more than the order of magnitude.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20600/99 | 1999-01-28 | ||
| JP20600/1999 | 1999-01-28 | ||
| JP02060099A JP3506629B2 (en) | 1999-01-28 | 1999-01-28 | Organic positive temperature coefficient thermistor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1264133A CN1264133A (en) | 2000-08-23 |
| CN1179369C true CN1179369C (en) | 2004-12-08 |
Family
ID=12031768
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB99120767XA Expired - Fee Related CN1179369C (en) | 1999-01-28 | 1999-09-28 | Organic positive temp. coefficient thermal resistance |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3506629B2 (en) |
| CN (1) | CN1179369C (en) |
| TW (1) | TW466509B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4276445B2 (en) | 2003-01-17 | 2009-06-10 | Ｔｄｋ株式会社 | Organic positive temperature coefficient thermistor and manufacturing method thereof |
| JPWO2004086421A1 (en) | 2003-03-25 | 2006-06-29 | Tdk株式会社 | Organic positive temperature coefficient thermistor |
| JP2005259823A (en) | 2004-03-09 | 2005-09-22 | Tdk Corp | Organic ptc thermistor and its manufacturing method |
| JP2006013378A (en) | 2004-06-29 | 2006-01-12 | Tdk Corp | Thermistor element body forming resin composition and thermistor |
| JP5017522B2 (en) * | 2005-09-13 | 2012-09-05 | 株式会社アイ．エス．テイ | Planar heating element and manufacturing method thereof |
| EP3021331A1 (en) * | 2014-11-17 | 2016-05-18 | Henkel AG & Co. KGaA | Positive temperature coefficient composition |
| JP6349442B1 (en) * | 2017-05-23 | 2018-06-27 | 株式会社フジクラ | Composite membrane and battery |
-
1999
- 1999-01-28 JP JP02060099A patent/JP3506629B2/en not_active Expired - Fee Related
- 1999-07-30 TW TW88113032A patent/TW466509B/en not_active IP Right Cessation
- 1999-09-28 CN CNB99120767XA patent/CN1179369C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000223303A (en) | 2000-08-11 |
| TW466509B (en) | 2001-12-01 |
| CN1264133A (en) | 2000-08-23 |
| JP3506629B2 (en) | 2004-03-15 |
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