CA1301986C - Polymer composition having positive temperature coefficient characteristics - Google Patents
Polymer composition having positive temperature coefficient characteristicsInfo
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- CA1301986C CA1301986C CA000524339A CA524339A CA1301986C CA 1301986 C CA1301986 C CA 1301986C CA 000524339 A CA000524339 A CA 000524339A CA 524339 A CA524339 A CA 524339A CA 1301986 C CA1301986 C CA 1301986C
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
- H01C7/027—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
Abstract
ABSTRACT OF THE DISCLOSURE
A polymer composition having positive temperature co-efficient characteristics is described, comprising 100 parts by weight of a mixture consisting of from 40 to 90% by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance. This polymer composition can withstand high voltage and when used as a heat generator, produces a uniform distribution of heat and has a long service life. Thus the polymer composition is useful for production of an overcurrent protecting element and a heat generator.
A polymer composition having positive temperature co-efficient characteristics is described, comprising 100 parts by weight of a mixture consisting of from 40 to 90% by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance. This polymer composition can withstand high voltage and when used as a heat generator, produces a uniform distribution of heat and has a long service life. Thus the polymer composition is useful for production of an overcurrent protecting element and a heat generator.
Description
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POLYMER COMPOSITION HAVING POSITIVE TEMPER~TURE
COEFFICIENT CHA~CTERISTICS
The present invention relates to a polymer composition having positive temperature coefficient characteristics of the electric resi~,tance and more particularly to a polymer composition having positive temperature coefficient characteristics which can withstand high voltage and further which when used as a heat generator, produces a uniform distribution of heat, has a long service life and thus can be utilized as an overcurrent-protecting element or a heat generator.
Composition prepared by compounding electrically conduc-tive particles sueh as carbon black to crystalline polymers or inorganic substances such as barium titanate are known to have the positive temperature ~oe~ficient characteristics that an lS electric resistane~e value abruptly increases when the temper-ature reaches a specified tempexature range (see, for example, Japanese Patent Publication Nos. 33707/1975 and 10352/1981).
These convenl:ional compositions are useful as overcurrent-protecting elemenl:s or heat generators. When, however, they are used under relatively high voltage conditions or unexpected overvoltage is applied thereto, they cannot withstand such relatively high voltage or unexpected overvoltage and thus are broken.
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SUMMARY OE` . THE INVENTION
The present invention is intended to overcome the above problems and an object of the present invention is to provide a polymer composition which has satisfactory positive temperature coefficient characteristics and can withstand sufficiently high voltage.
It has been found that the object can be attained by using a composition which is prepared by compounding a semiconductive inorganic substance to a mixture of a crystalline polymer and an electrically conductive powder.
The present invention relates to a polymer composition having positive temperature coefficient characteristics as prepared by compounding from 10 to 300 parts by weight of a semiconductive inorganic substance having a specific resistance of from 10 2 to lO~J~-cm to 100 parts by weight of a mixture of from 40 to 90% by weight of a crys~alline polymer and from 60 to 10% by weight of an elec~.rically conductive powder.
In another aspect this invention provides for a polymer composition having positive temperature coefficient characteristics, comprising lQ0 parts by weight of a mixture consisting of from 40 to 90~ by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance, wherein ~he semiconductive inorganic substance is silicon carbide, boron carbide or a mixture thereof.
POLYMER COMPOSITION HAVING POSITIVE TEMPER~TURE
COEFFICIENT CHA~CTERISTICS
The present invention relates to a polymer composition having positive temperature coefficient characteristics of the electric resi~,tance and more particularly to a polymer composition having positive temperature coefficient characteristics which can withstand high voltage and further which when used as a heat generator, produces a uniform distribution of heat, has a long service life and thus can be utilized as an overcurrent-protecting element or a heat generator.
Composition prepared by compounding electrically conduc-tive particles sueh as carbon black to crystalline polymers or inorganic substances such as barium titanate are known to have the positive temperature ~oe~ficient characteristics that an lS electric resistane~e value abruptly increases when the temper-ature reaches a specified tempexature range (see, for example, Japanese Patent Publication Nos. 33707/1975 and 10352/1981).
These convenl:ional compositions are useful as overcurrent-protecting elemenl:s or heat generators. When, however, they are used under relatively high voltage conditions or unexpected overvoltage is applied thereto, they cannot withstand such relatively high voltage or unexpected overvoltage and thus are broken.
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SUMMARY OE` . THE INVENTION
The present invention is intended to overcome the above problems and an object of the present invention is to provide a polymer composition which has satisfactory positive temperature coefficient characteristics and can withstand sufficiently high voltage.
It has been found that the object can be attained by using a composition which is prepared by compounding a semiconductive inorganic substance to a mixture of a crystalline polymer and an electrically conductive powder.
The present invention relates to a polymer composition having positive temperature coefficient characteristics as prepared by compounding from 10 to 300 parts by weight of a semiconductive inorganic substance having a specific resistance of from 10 2 to lO~J~-cm to 100 parts by weight of a mixture of from 40 to 90% by weight of a crys~alline polymer and from 60 to 10% by weight of an elec~.rically conductive powder.
In another aspect this invention provides for a polymer composition having positive temperature coefficient characteristics, comprising lQ0 parts by weight of a mixture consisting of from 40 to 90~ by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance, wherein ~he semiconductive inorganic substance is silicon carbide, boron carbide or a mixture thereof.
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DETAILED DESCRIPTION OF THE INVENTION
There are no special limitations to the crystalline polymer as used herein; various crystalline polymers can be used in the present invention. Typical examples of such crystalline polymers are polyolefins such as high density polyethylene, low density polyethylene, polypropylene, olefin copolymers such as ethylene-propylene copolymer, and ethylene-vinylacetate copolymer, polyamide, polyester, fluorine-containing ethylene-based polymer and their modified products. These compounds can be used alone or in combination with each other.
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1 As the electrically conductive powder as used herein, various electrically conductive powders can be used, Typical examples of such powders are carbon black such as oil furnace black, thermal black and acetylene black; graphite; metal powders; powdered carbon fibers, and mixtures thereof.
Particularly preferred are carbon black and graphite. Carbon black as used herein has an average particle diameter o~ from 10 to 200 m~, prei-erably from 15 to 100 m~. If the average particle diameter is less than 10 m~, the electric resistance does not sufficiently increase when the specified temperature range is reached. On the other hand, if the average particle diameter is in excess of 20Q m~, the electric resistance at room temperature ~mdesirably increases.
A mixture of two or more electrically conductive powders having varied part:icle diameters may be used as the above electrically conductive powder.
In the above crystalline polymer-electrically conductive powder mixture, the proportion of the crystalline polymer is from 40 to 90~ by weight and preerably from 50 to 80% by weight, and the proportion of the electrically conductive powder is from 60 to 10~ by weight and preferably from 50 to 20% by ~eight:. If the proportion of ~he electrically conductive powder is in excess of the above upper limitt sufficiently satisfactory positive tempexature coef-ficient characteristics cannot be obtained~ If the proportionof the electrically conductive powder is less than the above lower limit, suffi~iently satisfactory electrical conductivity cannot be obtained.
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1 The polymer composition of the present inventlon is prepared by compounding a semiconductive inoXganic substance having a specific resistance of from 10-2 to 108 Q-cm to the above crystalline polymer-electrically conductive powder mixture. Typical examples of semiconductive inorganic sub-stances which can be used are carbides such as silicon carbide and boron carbide, and titanium black. of these com-pounds, carbides such as silicon carbide and boron carbide are preferred.
The semiconductive inorganic substance is in either a powdery form or a fibrous form. The s0miconductive inorganic powder has an avelage particle diameter of not more than 300 ~m and preferably nct more than 100 ~m. I the average particle diameter is in excess of 300 ~m, the effect of increasing voltage resistance! i.s und~sirably decreased. In connection with the semicond~lctive inorganic fiber, it is preferred that the diameter is ~rom 0.1 to 100 ~m and the length is from 1 ~o 5,000 ~Im.
In compounding the semiconductive inorganic substance to the crystalline pcl~mer-electrically conductive powder mixture, the amount of the semiconductive inorganic substance compounded is from 10 to 300 parts by weight, preferably from 15 to 200 parts by weight per 100 parts by weight of the mixture. If ~he amount of the semiconductive inorganic sub~tance compounded is less than 10 ~arts by weiyht~ sufficiently satisfactory voltage resistance cannot be obtained. On the other hand, i~
the amount of the semiconductive inorganic substance compounded is in excess of 300 parts by weight, the resulting mixture .
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1 undesirably becomes dif~icult to knead.
The above two components are kneaded by the usual techniques such as by the use of usual kneading machines, e.g., a Banbury's mixer and a kneading roll. The kneading temperature is not critical. It is usually not lower than the melting point o~ the crystalline polymer to be used and preferably at least 30C higher than the melting point of the crystalline polymer to be used. By kneading the two components at the above defined temperature, the speci~ic resistance at ordinary temperature can be decreased. In connection with the kneading time, it suffices that the kneading time after a temperature higher than the melting point of the crystalline polymer to be usecl is reached is not less than 5 minutes.
During the proces~' of kneading or after kneading, a cross-linking agent, e.g. organic peroxides may be added~ Typicale~amples of organic peroxides which can be used are 2,5-di-methyl~2,5-di(tert-butylperoxy)hexyne-3, benzoyl peroxide, tert-butylperoxy ~)en20ate, dicumyl peroxide r tert-butylcumyl peroxide, and di tert-but~l peroxide. If desired, the kneaded material may be cross-linked with radiations ater its moldin~.
The above-pr~!pared pol~mer composi~ion having positive temperature coefficient characteristics is molded into desired forms by various known techniques to produce the final products such as an electric element.
The polymer composition of the present invention permits production of electric elements having such positive temper-ature coefficient characteristics that the voltage resistance, particularly the resistance against instantaneous overvoltage . .
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1 is high. A heat generator producedby molding the polymer com-position of the pxesent invention produces uniform distri-bution of heat and has a long service life because the semi-conductive inorganic component genexates heat at the same time and is excellent in heat conductivity. In addition, the polymer composition of the present invention is high in the resistance increasing rate when a specified temperature range is reached.
Accordingly the polymer composition of the present invention can be used in production of overcurrent protecting elements, heat generators, in particular, high voltage over-current protecting elements.
The present invention is described in greater detail with reference to the following examples.
Twenty-our grams (g) of high density polyethylene (Idemitsu Polyethylene 520B produced by Idemitsu Petrochemical Co., Ltd.) as a crystalline polymer and 16 g of carbon black (Dia~lack ~ produced by Mitsubishi Chemical Industries Ltd.;
average particle diameter: ~3 m~) as an electrically conductive powder were mixed. To 100 parts by weight of the resulting mixture was compounded with 100 parts by weight of silicon carbide powder (SiC #4000 produced by Fujimi Kenmazai Kogyo Co., Ltd.; average particle diameter: 3 ~m; specific resistance: llOQ~cm), and the resulting mixture was introduced in a kneader ~Laboplastomill produced by Toyo Seiki Seisakusho Co., Ltd~) where it was melted and kneaded. Then 0.6 part * Trade Mark ` ~3~8~i 1 by weight of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3 was added as a cross-linking agent, and the resultin~ mixture was further kneaded to prepare a polymer composi-tion having positive temperature coefficient characteristics~
The above-prepared polymer composition was press molded to produce a sheet. Th:is sheet was sandwiched between two electrolytic nickel foils (Fukuda Metal Foil & Powder Co., Ltd.~ having a thickness of 35 ~m and then pressed hy the use of a press moldin~ machine to produce a 1.8 mm thick laminated sheet. A 8 mm x ~ mm piece was cut away from the laminated sheet. The elect~-ic resistance at room temperature between the nickel foils ~las measured and found to be 20 Q (specific resistance: 80 Q-cm). Then the piece was heated to 130C and at this temperature, measured for the electric resistance.
lS The ratio of the ~!lectriG resistance at 130C to that at xoom temperature (resi~;tance increasing rate) was 106 ~ I ~ In addi-tion, the piece wc,s measured for a dynamic voltage resistance, i.e., a voltage at: which the piece was broken when it was applied instantan~!ously to the piece at room temperature.
The dynamic voltac~e xesistance was 630 V. In conneckion with a static voltage xesis~ance, i.e., a voltage at which the piece was broken when it was gradually applied to the piece, even if the voltaye was increased to 1,000 V, the p;.ece was not broken.
Lead-wires were soldered to the nickel foilsr and the piece was entixely covered with an epoxy resin. This piece was measured for the dynamic and static voltage resistances in the same manner as above with tlle same results as a~ove~
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A laminated sheet was produced in the same mannex as in Example 1 except that 100 parts by weight of boron carbide powder (Denkaboron Fl produced by Denki Kagaku Kogyo K.K.;
average particle diameter: 5 ~m; specific resistance: 0.55 Q-cm) was used as the semiconductive inorganic substance.
A 7 mm x 8 mm piece was cut away from the laminated sheet and measured for the electric resistance at room temperature.
The electric resistance at room temperature was 20 n (specific resistance: 62 Q-cm). The resistance increasing rate at 130C
was 106 2. The dynamic voltage resistance of the piece was 450 V. In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
Lead-wires were connected to the piece in the same manner as in Example 1. This piece was entirely covered with an epoxy resin and measured for the dynamic and static voltage resist-ances with the same results as a~ove.
The same high density polyethylene-carbon black mixture as in Example 1 was kneaded in a kneader (Laboplastomill), and then the same cross-linking agent as in Example 1 was added to prepare a kneaded composition. Using this composition, a 2.0 mm thick laminated sheet was produced in the same manner as in Example 1.
A 8 mm x ~ mm piece was cut away from the above laminated sheet, and then measured for the electric resistance at room temperature. The electric resistan¢e at room temperature ~i * Trade Mark ~.. J , ;` ~
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1 was 20 Q (specific resistance 64 Q-cm). The resistance increasing rate when the temperature was raised to 130C was 107'5. The dynamic voltage resistance of the piece was 300 V.
In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
A 1.8 mm thick laminated sheet was produced in the same manner as in Example 1 except that 100 parts by weight of aluminum hydroxide (B703 produced by Nippon Light Metal Co., Ltd.; av~erage particle diameter: 0.4 ~m), which was electrically insulative, was used in place of the silicon carbide powder.
A 6 mm x 6 mn piece was cut away from the above laminated sheet and measured for the electric resistance at room temperature.
~ The electric resistance at room temperature was 20 Q (specific resis~ance: 40 Q--m). The resistance increasing rate when the temparature was r~ised to 130C was 1061. The dynamic voltage resist~nce of the piece was 355 V and the static voltage resist~
ance was 700 V.
24.6 g of high density polyethylene (Idemitsu Polyethylene 540B produced by Idemitsu Petrochemical Co., Ltd.) as a crystalline polymer and 15.4 g of carbon black (Diablack E
produced by Mitsubishi Chemical Industries, Ltd.; average particle diameter: 43 m~) as an el~ctrically conductive 25 powder were mixecl. To 100 parts by weight of the resulting mixture was compounded wîth 100 parts by weight of silicoll 3~86 1 carbide powder (SiC #2000 produced by Fujimi Kenmazai Kogyo CoO~ Ltd.; average particle diameter; about 8 ~m; specific resistance: 90 Q~cm), and the resulting mixture was in~roduced in a kneader (Laboplastomill) where it was melted and kneaded.
Then 0.1~ part by weight of 2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexyne-3 was added as a cross-linking agent, and the resulting mixture was further kneaded to prepare a polymer composition havins~ positive temperature coefficient characteristics.
The above-prepared polymer composition was press molded to produce a sheet:O This sheet was sandwiched between two electrolytic nickel foils with one sided rough phase having a thickness of 20 ~m and then pressed by the use of a hot press molding maclline to produce a 1.~ mm thick laminated sh~et. A S mm x !3 mm piece was cut away from the laminated æh~et. The electric resistance at r~om temperature between thq nickel ~oils ~as measured and found to be 20 ~ (specific resistance: 50 Q-o~m). The resistance increasing rate at 130nC
was 105 ~. l'he d~namic voltage resistance of the pie~e was 600 V. In connecl:ion with the static voltage resistance, khe piece was not bro]cen even at 1,000 V. Lead-wires were connected to the piece, and said piece was entirely covered with an epoxy resin in the same manner as in Example 1, and measured for the dynamic voltage resistance, and it was 630 V.
In connection with the stati~ voltase resistanc~, t:he piece was not broken even at lfO00 V~
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A laminated sheet was produced in the same manner as in Example 3 except that 125 parts by weight of silicon carbide powder (SiC ~4000 produced by Fujimi Kenmazai Kogyo Co., Ltd,) was added to 100 parts by weight of the mixture comprising 21.2 g of high density polyethylene and 14.9 g of carbon black.
A 6 mm x 7 mm piece was cut away from the laminated sheet, and measured for the electric resistance at room temperature. The electric resistance at r~om temperature was 20 Q (specific resistance: 47 ~-cm). The resistance increasing rate at: 130C was 105-. The dynamic voltage . resistance of the piece was 560 V~ In connection with the static voltage re~;istance, the piece was not broken even at 1, 000 V.
Lead-WireS were connected to the piece, and said piece was entirely covered with an epoxy resin in the same manner as in Example 1, and me,asured,o~ the.dyna~ic,,yo-lt~ge xes~i.stance, and it wa,s ,6.0~V. In c.onhect~i.'on ~wit~ the static.~oltage , resi,s~,~hc~,:t~e pie.-ce was,not ~roken even at 1,000 V.
zo COMPARATIVE EXA~ l:,E 3 A laminated sheet was produced i~ the same manner as in Example 3 except that 100 parts by wei~ht of silicon ~itride powder (SN-B produced by'Denki Kagaku Kogyo K.K.;
average particle diameterO <44 ~m; speciflc resistance:
>11~ Q-cm) was added to 100 parts by weight of the mixture . comprising 25.4 g of high density polyethylene and 14~6 ~
, of carbon black a~d 0~19 parts by weight of the cross-linking ~, J
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1 agent was used.
A 5 mm x 9 mm piece was cut away from the laminated sheet, and measured for the electric resistance at room temperature.
The electric resistance at room temperature was 20 Q ~specific resistance: 50 Q-cm). The resistance increasing rate was 106 3. The dynamic voltage resistance of the piece was 315 V.
In conn~ction with the static voltage resistance, the piece was not broken even at 1, noo v.
Lead-~ires were connected to the piece, and the piece was entirely covered with an epoxy resin. The dynamic voltage resistance of the piece was 355 V. In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
COMP~RATI~E EXAMPLE 4 A laminated ~heet was produced in the same manner as in ~xample 3 except t:hat 100 parts by weight of titanium nitride powder (TiN produc~ed by Nippon Shinkinzoku Co., Ltd.; average pa~ticle diameter: about 1.5 ~m; specific resistance: 4 x 10-5 ~-cm) was added tc~ lOQ parts by weight of the mixture comprising 29~7 g of high derlsity polyethylene and 15.3 g of carbon blackF
and 0.20 parts by weight of the cross-linking agent was used.
A 5 mm x 9 mm piece was cut away from the laminated sheet, and measured ox the electric resistance at room temperature.
The electric resistance at room temperatllre was ~0 ~ (spe~i~
r~sistanceO 50 Q cm~, The resistance increasing rate was 10~ 20 The dynamic voltage resistance of the piece was 280 V~
and the static voltage resistance of the piece was 700 V.
~3~9~36 1 Lead-wires were connected to the piece in the same manner as in Example 1. This piece was entirely covered ~ith an epoxy resin and measured for the dynamic and static voltage resist-ances with the same results as above.
5 ExAMæLE _ Thirty-two grams of low density polyethylene (Petrothene-170 produced by Toyo Soda Kogyo Co., Ltd.) and 19 g of carbon black (same as in Example 1) were mixed. To 100 parts by weight of the resulting mixture was compounded with 96 parts by weight of silicon carbide powder (SiC #4000), and the resulting mixture was introduced in a kneader (Laboplastomill) where it was melted and kneaded to obtain a polymer composition.
A 10 mm x 10 mm plece was cut away from the laminated sheet having a thickness of 1 mm which was prepared in the same manner as in ~xample 3. The electric resistance at room temperature was measured and the specific resistance was 56 Q-cm, and the resistance increasing rate was 104- 6 .
A 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wires were connected to the piece, and it was coated by black paint. After 30 V of DC was charged for 5 minutes, the tempexature distribution of the surface was measured b~ infrared imager (infrared indication thermometer).
The heighest temperature of the surface was 99C and the difference between said heighest temperature and the lowest temperature was 4C. Accordingly, it was found that the surface temperature is almost uniform, and the temperature at the eenter of the surface is higher, while the temperature * Trade Mark ~.. , . .
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1 at the surroundings is lower due to the radiation. The result shows that the temperature distribution of the surface is proper. The change of the surface temperature was +1% after charge for 200 hours and also the change in the resistance s value after cooling was ~0~.
Thirty-five grams of ethylene-vinyl acetate copolymers (Ultrathene-UE-634 produced by Toyo Soda Xogyo Co., Ltd.) and 26 g of carbon black (same as in Example 1) were mixed.
To 100 parts by weight of the resulting mixture was compounded with 64 parts by weight of silicon carbide (SiC #4000), and the resulting mixture was introduced in a kneader (Laboplastomill) where it was melted and kneaded to obtain a polymer composition.
A 10 mm x 10 mm piece was cut away from the laminated 15 sheet having a thickness of 1 mm which was prepared in the same manner as in Example 3. The electric resistance at room temperature was measured and the specific resistance was 62 Q-cm, and the re~istance increasing rate was 103- 2 .
A 40 mm x 40 mm piece was cut away from the laminated 20 sheet, and lead-wires were connected to the piece. A~er 30 V of DC was charged for 5 minutes, the temperature distribution of the surface was measured as in Example 5, and found that the heighest temperature of the surface was 72C
and the difference between said heighest temperature and the 25 lowest temperature was 6C. Accordingly, it was found that the surface temperature is almost uniform and the temperature distribution of the surface is proper. The change of the * Trade Mark . .
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1 surface temperature was -2% after charge for 200 hours and also the change in the resistance value after cooling was +20~.
Test piece was obtained in the same manner as in Example 5 except that 49 g of low density polyethylene and 21 g of carhon black were used. The specific resistance of the piece was 60 Q-cm~ and the resistance increasing rate was ~ 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wi.res were connected to the piece. After 30 V of DC was charged for 5 minutes, the temperature distribu-tion of the surface was measured as in Example 5, and found that the heighest temperatuxe of the surace was 75C and the difference between said heighest temperature and the lowest temperature was more than 10C~ Furthermore, the temperature distributi.on of tlle surface was random. The change of the su~face temperature was ~6~ after charge for 200 hours and also the chan~e in the resistance value after cooling was ~ 0% .
COMPAR~TIVE EXAMPLE 6 Test piece was obtained in the same manner as in Example 6 except that 40 g of eth~lene-vinyl acetate copolymer and 30 g of carbon black were used. The speaiic resi.stance o the piece was 60 ~-cm, and the resistance increasing rate 25 was 103- 3.
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1 A 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wires were connected to the piece. After 30 V
of DC was charged for 5 minutes, the temperature distribution of the surface was measured as in Example 5, and found that the heighest tempexature was 67C and the difference between said heighest temperature and the lowest temperature was 10C. Furthermore, the temperature distribution of the surface was random. The change of the surface temperature was ~20% ater charge for 200 hours and also the change in 10 the resistance va.lue after cooling was ~50%.
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DETAILED DESCRIPTION OF THE INVENTION
There are no special limitations to the crystalline polymer as used herein; various crystalline polymers can be used in the present invention. Typical examples of such crystalline polymers are polyolefins such as high density polyethylene, low density polyethylene, polypropylene, olefin copolymers such as ethylene-propylene copolymer, and ethylene-vinylacetate copolymer, polyamide, polyester, fluorine-containing ethylene-based polymer and their modified products. These compounds can be used alone or in combination with each other.
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1 As the electrically conductive powder as used herein, various electrically conductive powders can be used, Typical examples of such powders are carbon black such as oil furnace black, thermal black and acetylene black; graphite; metal powders; powdered carbon fibers, and mixtures thereof.
Particularly preferred are carbon black and graphite. Carbon black as used herein has an average particle diameter o~ from 10 to 200 m~, prei-erably from 15 to 100 m~. If the average particle diameter is less than 10 m~, the electric resistance does not sufficiently increase when the specified temperature range is reached. On the other hand, if the average particle diameter is in excess of 20Q m~, the electric resistance at room temperature ~mdesirably increases.
A mixture of two or more electrically conductive powders having varied part:icle diameters may be used as the above electrically conductive powder.
In the above crystalline polymer-electrically conductive powder mixture, the proportion of the crystalline polymer is from 40 to 90~ by weight and preerably from 50 to 80% by weight, and the proportion of the electrically conductive powder is from 60 to 10~ by weight and preferably from 50 to 20% by ~eight:. If the proportion of ~he electrically conductive powder is in excess of the above upper limitt sufficiently satisfactory positive tempexature coef-ficient characteristics cannot be obtained~ If the proportionof the electrically conductive powder is less than the above lower limit, suffi~iently satisfactory electrical conductivity cannot be obtained.
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1 The polymer composition of the present inventlon is prepared by compounding a semiconductive inoXganic substance having a specific resistance of from 10-2 to 108 Q-cm to the above crystalline polymer-electrically conductive powder mixture. Typical examples of semiconductive inorganic sub-stances which can be used are carbides such as silicon carbide and boron carbide, and titanium black. of these com-pounds, carbides such as silicon carbide and boron carbide are preferred.
The semiconductive inorganic substance is in either a powdery form or a fibrous form. The s0miconductive inorganic powder has an avelage particle diameter of not more than 300 ~m and preferably nct more than 100 ~m. I the average particle diameter is in excess of 300 ~m, the effect of increasing voltage resistance! i.s und~sirably decreased. In connection with the semicond~lctive inorganic fiber, it is preferred that the diameter is ~rom 0.1 to 100 ~m and the length is from 1 ~o 5,000 ~Im.
In compounding the semiconductive inorganic substance to the crystalline pcl~mer-electrically conductive powder mixture, the amount of the semiconductive inorganic substance compounded is from 10 to 300 parts by weight, preferably from 15 to 200 parts by weight per 100 parts by weight of the mixture. If ~he amount of the semiconductive inorganic sub~tance compounded is less than 10 ~arts by weiyht~ sufficiently satisfactory voltage resistance cannot be obtained. On the other hand, i~
the amount of the semiconductive inorganic substance compounded is in excess of 300 parts by weight, the resulting mixture .
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1 undesirably becomes dif~icult to knead.
The above two components are kneaded by the usual techniques such as by the use of usual kneading machines, e.g., a Banbury's mixer and a kneading roll. The kneading temperature is not critical. It is usually not lower than the melting point o~ the crystalline polymer to be used and preferably at least 30C higher than the melting point of the crystalline polymer to be used. By kneading the two components at the above defined temperature, the speci~ic resistance at ordinary temperature can be decreased. In connection with the kneading time, it suffices that the kneading time after a temperature higher than the melting point of the crystalline polymer to be usecl is reached is not less than 5 minutes.
During the proces~' of kneading or after kneading, a cross-linking agent, e.g. organic peroxides may be added~ Typicale~amples of organic peroxides which can be used are 2,5-di-methyl~2,5-di(tert-butylperoxy)hexyne-3, benzoyl peroxide, tert-butylperoxy ~)en20ate, dicumyl peroxide r tert-butylcumyl peroxide, and di tert-but~l peroxide. If desired, the kneaded material may be cross-linked with radiations ater its moldin~.
The above-pr~!pared pol~mer composi~ion having positive temperature coefficient characteristics is molded into desired forms by various known techniques to produce the final products such as an electric element.
The polymer composition of the present invention permits production of electric elements having such positive temper-ature coefficient characteristics that the voltage resistance, particularly the resistance against instantaneous overvoltage . .
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1 is high. A heat generator producedby molding the polymer com-position of the pxesent invention produces uniform distri-bution of heat and has a long service life because the semi-conductive inorganic component genexates heat at the same time and is excellent in heat conductivity. In addition, the polymer composition of the present invention is high in the resistance increasing rate when a specified temperature range is reached.
Accordingly the polymer composition of the present invention can be used in production of overcurrent protecting elements, heat generators, in particular, high voltage over-current protecting elements.
The present invention is described in greater detail with reference to the following examples.
Twenty-our grams (g) of high density polyethylene (Idemitsu Polyethylene 520B produced by Idemitsu Petrochemical Co., Ltd.) as a crystalline polymer and 16 g of carbon black (Dia~lack ~ produced by Mitsubishi Chemical Industries Ltd.;
average particle diameter: ~3 m~) as an electrically conductive powder were mixed. To 100 parts by weight of the resulting mixture was compounded with 100 parts by weight of silicon carbide powder (SiC #4000 produced by Fujimi Kenmazai Kogyo Co., Ltd.; average particle diameter: 3 ~m; specific resistance: llOQ~cm), and the resulting mixture was introduced in a kneader ~Laboplastomill produced by Toyo Seiki Seisakusho Co., Ltd~) where it was melted and kneaded. Then 0.6 part * Trade Mark ` ~3~8~i 1 by weight of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3 was added as a cross-linking agent, and the resultin~ mixture was further kneaded to prepare a polymer composi-tion having positive temperature coefficient characteristics~
The above-prepared polymer composition was press molded to produce a sheet. Th:is sheet was sandwiched between two electrolytic nickel foils (Fukuda Metal Foil & Powder Co., Ltd.~ having a thickness of 35 ~m and then pressed hy the use of a press moldin~ machine to produce a 1.8 mm thick laminated sheet. A 8 mm x ~ mm piece was cut away from the laminated sheet. The elect~-ic resistance at room temperature between the nickel foils ~las measured and found to be 20 Q (specific resistance: 80 Q-cm). Then the piece was heated to 130C and at this temperature, measured for the electric resistance.
lS The ratio of the ~!lectriG resistance at 130C to that at xoom temperature (resi~;tance increasing rate) was 106 ~ I ~ In addi-tion, the piece wc,s measured for a dynamic voltage resistance, i.e., a voltage at: which the piece was broken when it was applied instantan~!ously to the piece at room temperature.
The dynamic voltac~e xesistance was 630 V. In conneckion with a static voltage xesis~ance, i.e., a voltage at which the piece was broken when it was gradually applied to the piece, even if the voltaye was increased to 1,000 V, the p;.ece was not broken.
Lead-wires were soldered to the nickel foilsr and the piece was entixely covered with an epoxy resin. This piece was measured for the dynamic and static voltage resistances in the same manner as above with tlle same results as a~ove~
.
- . ~ .
.
`- ~3~L3~
A laminated sheet was produced in the same mannex as in Example 1 except that 100 parts by weight of boron carbide powder (Denkaboron Fl produced by Denki Kagaku Kogyo K.K.;
average particle diameter: 5 ~m; specific resistance: 0.55 Q-cm) was used as the semiconductive inorganic substance.
A 7 mm x 8 mm piece was cut away from the laminated sheet and measured for the electric resistance at room temperature.
The electric resistance at room temperature was 20 n (specific resistance: 62 Q-cm). The resistance increasing rate at 130C
was 106 2. The dynamic voltage resistance of the piece was 450 V. In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
Lead-wires were connected to the piece in the same manner as in Example 1. This piece was entirely covered with an epoxy resin and measured for the dynamic and static voltage resist-ances with the same results as a~ove.
The same high density polyethylene-carbon black mixture as in Example 1 was kneaded in a kneader (Laboplastomill), and then the same cross-linking agent as in Example 1 was added to prepare a kneaded composition. Using this composition, a 2.0 mm thick laminated sheet was produced in the same manner as in Example 1.
A 8 mm x ~ mm piece was cut away from the above laminated sheet, and then measured for the electric resistance at room temperature. The electric resistan¢e at room temperature ~i * Trade Mark ~.. J , ;` ~
, . . , . ., ,, .... . . , . , .. , . . .... . , ... . .. . .... . , . . , -, . --.
~l3U~
1 was 20 Q (specific resistance 64 Q-cm). The resistance increasing rate when the temperature was raised to 130C was 107'5. The dynamic voltage resistance of the piece was 300 V.
In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
A 1.8 mm thick laminated sheet was produced in the same manner as in Example 1 except that 100 parts by weight of aluminum hydroxide (B703 produced by Nippon Light Metal Co., Ltd.; av~erage particle diameter: 0.4 ~m), which was electrically insulative, was used in place of the silicon carbide powder.
A 6 mm x 6 mn piece was cut away from the above laminated sheet and measured for the electric resistance at room temperature.
~ The electric resistance at room temperature was 20 Q (specific resis~ance: 40 Q--m). The resistance increasing rate when the temparature was r~ised to 130C was 1061. The dynamic voltage resist~nce of the piece was 355 V and the static voltage resist~
ance was 700 V.
24.6 g of high density polyethylene (Idemitsu Polyethylene 540B produced by Idemitsu Petrochemical Co., Ltd.) as a crystalline polymer and 15.4 g of carbon black (Diablack E
produced by Mitsubishi Chemical Industries, Ltd.; average particle diameter: 43 m~) as an el~ctrically conductive 25 powder were mixecl. To 100 parts by weight of the resulting mixture was compounded wîth 100 parts by weight of silicoll 3~86 1 carbide powder (SiC #2000 produced by Fujimi Kenmazai Kogyo CoO~ Ltd.; average particle diameter; about 8 ~m; specific resistance: 90 Q~cm), and the resulting mixture was in~roduced in a kneader (Laboplastomill) where it was melted and kneaded.
Then 0.1~ part by weight of 2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexyne-3 was added as a cross-linking agent, and the resulting mixture was further kneaded to prepare a polymer composition havins~ positive temperature coefficient characteristics.
The above-prepared polymer composition was press molded to produce a sheet:O This sheet was sandwiched between two electrolytic nickel foils with one sided rough phase having a thickness of 20 ~m and then pressed by the use of a hot press molding maclline to produce a 1.~ mm thick laminated sh~et. A S mm x !3 mm piece was cut away from the laminated æh~et. The electric resistance at r~om temperature between thq nickel ~oils ~as measured and found to be 20 ~ (specific resistance: 50 Q-o~m). The resistance increasing rate at 130nC
was 105 ~. l'he d~namic voltage resistance of the pie~e was 600 V. In connecl:ion with the static voltage resistance, khe piece was not bro]cen even at 1,000 V. Lead-wires were connected to the piece, and said piece was entirely covered with an epoxy resin in the same manner as in Example 1, and measured for the dynamic voltage resistance, and it was 630 V.
In connection with the stati~ voltase resistanc~, t:he piece was not broken even at lfO00 V~
~ 10 -' ' ~3~9~
A laminated sheet was produced in the same manner as in Example 3 except that 125 parts by weight of silicon carbide powder (SiC ~4000 produced by Fujimi Kenmazai Kogyo Co., Ltd,) was added to 100 parts by weight of the mixture comprising 21.2 g of high density polyethylene and 14.9 g of carbon black.
A 6 mm x 7 mm piece was cut away from the laminated sheet, and measured for the electric resistance at room temperature. The electric resistance at r~om temperature was 20 Q (specific resistance: 47 ~-cm). The resistance increasing rate at: 130C was 105-. The dynamic voltage . resistance of the piece was 560 V~ In connection with the static voltage re~;istance, the piece was not broken even at 1, 000 V.
Lead-WireS were connected to the piece, and said piece was entirely covered with an epoxy resin in the same manner as in Example 1, and me,asured,o~ the.dyna~ic,,yo-lt~ge xes~i.stance, and it wa,s ,6.0~V. In c.onhect~i.'on ~wit~ the static.~oltage , resi,s~,~hc~,:t~e pie.-ce was,not ~roken even at 1,000 V.
zo COMPARATIVE EXA~ l:,E 3 A laminated sheet was produced i~ the same manner as in Example 3 except that 100 parts by wei~ht of silicon ~itride powder (SN-B produced by'Denki Kagaku Kogyo K.K.;
average particle diameterO <44 ~m; speciflc resistance:
>11~ Q-cm) was added to 100 parts by weight of the mixture . comprising 25.4 g of high density polyethylene and 14~6 ~
, of carbon black a~d 0~19 parts by weight of the cross-linking ~, J
~3~
1 agent was used.
A 5 mm x 9 mm piece was cut away from the laminated sheet, and measured for the electric resistance at room temperature.
The electric resistance at room temperature was 20 Q ~specific resistance: 50 Q-cm). The resistance increasing rate was 106 3. The dynamic voltage resistance of the piece was 315 V.
In conn~ction with the static voltage resistance, the piece was not broken even at 1, noo v.
Lead-~ires were connected to the piece, and the piece was entirely covered with an epoxy resin. The dynamic voltage resistance of the piece was 355 V. In connection with the static voltage resistance, the piece was not broken even at 1,000 V.
COMP~RATI~E EXAMPLE 4 A laminated ~heet was produced in the same manner as in ~xample 3 except t:hat 100 parts by weight of titanium nitride powder (TiN produc~ed by Nippon Shinkinzoku Co., Ltd.; average pa~ticle diameter: about 1.5 ~m; specific resistance: 4 x 10-5 ~-cm) was added tc~ lOQ parts by weight of the mixture comprising 29~7 g of high derlsity polyethylene and 15.3 g of carbon blackF
and 0.20 parts by weight of the cross-linking agent was used.
A 5 mm x 9 mm piece was cut away from the laminated sheet, and measured ox the electric resistance at room temperature.
The electric resistance at room temperatllre was ~0 ~ (spe~i~
r~sistanceO 50 Q cm~, The resistance increasing rate was 10~ 20 The dynamic voltage resistance of the piece was 280 V~
and the static voltage resistance of the piece was 700 V.
~3~9~36 1 Lead-wires were connected to the piece in the same manner as in Example 1. This piece was entirely covered ~ith an epoxy resin and measured for the dynamic and static voltage resist-ances with the same results as above.
5 ExAMæLE _ Thirty-two grams of low density polyethylene (Petrothene-170 produced by Toyo Soda Kogyo Co., Ltd.) and 19 g of carbon black (same as in Example 1) were mixed. To 100 parts by weight of the resulting mixture was compounded with 96 parts by weight of silicon carbide powder (SiC #4000), and the resulting mixture was introduced in a kneader (Laboplastomill) where it was melted and kneaded to obtain a polymer composition.
A 10 mm x 10 mm plece was cut away from the laminated sheet having a thickness of 1 mm which was prepared in the same manner as in ~xample 3. The electric resistance at room temperature was measured and the specific resistance was 56 Q-cm, and the resistance increasing rate was 104- 6 .
A 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wires were connected to the piece, and it was coated by black paint. After 30 V of DC was charged for 5 minutes, the tempexature distribution of the surface was measured b~ infrared imager (infrared indication thermometer).
The heighest temperature of the surface was 99C and the difference between said heighest temperature and the lowest temperature was 4C. Accordingly, it was found that the surface temperature is almost uniform, and the temperature at the eenter of the surface is higher, while the temperature * Trade Mark ~.. , . .
. . ' ~ 3~J~
1 at the surroundings is lower due to the radiation. The result shows that the temperature distribution of the surface is proper. The change of the surface temperature was +1% after charge for 200 hours and also the change in the resistance s value after cooling was ~0~.
Thirty-five grams of ethylene-vinyl acetate copolymers (Ultrathene-UE-634 produced by Toyo Soda Xogyo Co., Ltd.) and 26 g of carbon black (same as in Example 1) were mixed.
To 100 parts by weight of the resulting mixture was compounded with 64 parts by weight of silicon carbide (SiC #4000), and the resulting mixture was introduced in a kneader (Laboplastomill) where it was melted and kneaded to obtain a polymer composition.
A 10 mm x 10 mm piece was cut away from the laminated 15 sheet having a thickness of 1 mm which was prepared in the same manner as in Example 3. The electric resistance at room temperature was measured and the specific resistance was 62 Q-cm, and the re~istance increasing rate was 103- 2 .
A 40 mm x 40 mm piece was cut away from the laminated 20 sheet, and lead-wires were connected to the piece. A~er 30 V of DC was charged for 5 minutes, the temperature distribution of the surface was measured as in Example 5, and found that the heighest temperature of the surface was 72C
and the difference between said heighest temperature and the 25 lowest temperature was 6C. Accordingly, it was found that the surface temperature is almost uniform and the temperature distribution of the surface is proper. The change of the * Trade Mark . .
.. .. . .. . . . ... ..
:13~
1 surface temperature was -2% after charge for 200 hours and also the change in the resistance value after cooling was +20~.
Test piece was obtained in the same manner as in Example 5 except that 49 g of low density polyethylene and 21 g of carhon black were used. The specific resistance of the piece was 60 Q-cm~ and the resistance increasing rate was ~ 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wi.res were connected to the piece. After 30 V of DC was charged for 5 minutes, the temperature distribu-tion of the surface was measured as in Example 5, and found that the heighest temperatuxe of the surace was 75C and the difference between said heighest temperature and the lowest temperature was more than 10C~ Furthermore, the temperature distributi.on of tlle surface was random. The change of the su~face temperature was ~6~ after charge for 200 hours and also the chan~e in the resistance value after cooling was ~ 0% .
COMPAR~TIVE EXAMPLE 6 Test piece was obtained in the same manner as in Example 6 except that 40 g of eth~lene-vinyl acetate copolymer and 30 g of carbon black were used. The speaiic resi.stance o the piece was 60 ~-cm, and the resistance increasing rate 25 was 103- 3.
L98~
1 A 40 mm x 40 mm piece was cut away from the laminated sheet, and lead-wires were connected to the piece. After 30 V
of DC was charged for 5 minutes, the temperature distribution of the surface was measured as in Example 5, and found that the heighest tempexature was 67C and the difference between said heighest temperature and the lowest temperature was 10C. Furthermore, the temperature distribution of the surface was random. The change of the surface temperature was ~20% ater charge for 200 hours and also the change in 10 the resistance va.lue after cooling was ~50%.
Claims (2)
1. A polymer composition having positive temperature coefficient characteristics, comprising 100 parts by weight of a mixture consisting of from 40 to 90% by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance, wherein the semiconductive inorganic substance is silicon carbide, boron carbide or a mixture thereof.
2. A polymer composition as claimed in claim 1 wherein the semiconductive inorganic substance has a specific resistance of from 10-2 to 108?-cm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP270700/1985 | 1985-12-03 | ||
| JP60270700A JPS62131065A (en) | 1985-12-03 | 1985-12-03 | Polymer composition having positive temperature dependence |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1301986C true CA1301986C (en) | 1992-05-26 |
Family
ID=17489740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000524339A Expired - Fee Related CA1301986C (en) | 1985-12-03 | 1986-12-02 | Polymer composition having positive temperature coefficient characteristics |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4732701A (en) |
| EP (1) | EP0224903B1 (en) |
| JP (1) | JPS62131065A (en) |
| CA (1) | CA1301986C (en) |
| DE (1) | DE3687062T2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5143649A (en) * | 1985-12-06 | 1992-09-01 | Sunbeam Corporation | PTC compositions containing low molecular weight polymer molecules for reduced annealing |
| JPH0777161B2 (en) * | 1986-10-24 | 1995-08-16 | 日本メクトロン株式会社 | PTC composition, method for producing the same and PTC element |
| FR2614130B1 (en) * | 1987-04-15 | 1992-01-17 | Lorraine Carbone | MATERIAL HAVING A POSITIVE TEMPERATURE COEFFICIENT RESISTIVITY |
| US4880577A (en) * | 1987-07-24 | 1989-11-14 | Daito Communication Apparatus Co., Ltd. | Process for producing self-restoring over-current protective device by grafting method |
| US4849605A (en) * | 1988-03-11 | 1989-07-18 | Oki Electric Industry Co., Ltd. | Heating resistor and method for making same |
| US4910389A (en) * | 1988-06-03 | 1990-03-20 | Raychem Corporation | Conductive polymer compositions |
| JP2810740B2 (en) * | 1989-12-27 | 1998-10-15 | 大東通信機株式会社 | PTC composition by grafting method |
| JPH0688350B2 (en) * | 1990-01-12 | 1994-11-09 | 出光興産株式会社 | Positive temperature coefficient characteristic molded body manufacturing method |
| US5378407A (en) * | 1992-06-05 | 1995-01-03 | Raychem Corporation | Conductive polymer composition |
| CA2215959A1 (en) * | 1995-03-22 | 1996-09-26 | James Toth | Electrical device |
| ATE280995T1 (en) * | 1995-03-22 | 2004-11-15 | Tyco Electronics Corp | CONDUCTIVE POLYMER COMPOSITION AND DEVICE |
| JPH11505070A (en) * | 1995-05-10 | 1999-05-11 | リッテルフューズ，インコーポレイティド | PTC circuit protection device and method of manufacturing the same |
| US5663702A (en) * | 1995-06-07 | 1997-09-02 | Littelfuse, Inc. | PTC electrical device having fuse link in series and metallized ceramic electrodes |
| EP0845148B1 (en) * | 1995-08-15 | 2000-01-19 | Bourns Multifuse (Hong Kong), Ltd. | Surface mount conductive polymer devices and method for manufacturing such devices |
| TW309619B (en) * | 1995-08-15 | 1997-07-01 | Mourns Multifuse Hong Kong Ltd | |
| US6023403A (en) * | 1996-05-03 | 2000-02-08 | Littlefuse, Inc. | Surface mountable electrical device comprising a PTC and fusible element |
| US6020808A (en) | 1997-09-03 | 2000-02-01 | Bourns Multifuse (Hong Kong) Ltd. | Multilayer conductive polymer positive temperature coefficent device |
| US6282072B1 (en) | 1998-02-24 | 2001-08-28 | Littelfuse, Inc. | Electrical devices having a polymer PTC array |
| US6380839B2 (en) | 1998-03-05 | 2002-04-30 | Bourns, Inc. | Surface mount conductive polymer device |
| US6242997B1 (en) | 1998-03-05 | 2001-06-05 | Bourns, Inc. | Conductive polymer device and method of manufacturing same |
| US6172591B1 (en) | 1998-03-05 | 2001-01-09 | Bourns, Inc. | Multilayer conductive polymer device and method of manufacturing same |
| US6236302B1 (en) | 1998-03-05 | 2001-05-22 | Bourns, Inc. | Multilayer conductive polymer device and method of manufacturing same |
| WO2000019455A1 (en) | 1998-09-25 | 2000-04-06 | Bourns, Inc. | Two-step process for preparing positive temperature coefficient polymer materials |
| US6582647B1 (en) | 1998-10-01 | 2003-06-24 | Littelfuse, Inc. | Method for heat treating PTC devices |
| US6429533B1 (en) | 1999-11-23 | 2002-08-06 | Bourns Inc. | Conductive polymer device and method of manufacturing same |
| US6628498B2 (en) | 2000-08-28 | 2003-09-30 | Steven J. Whitney | Integrated electrostatic discharge and overcurrent device |
| EP1245361A1 (en) * | 2001-03-26 | 2002-10-02 | Abb Research Ltd. | Method for injection molding parts with electrically conductive elements and electrical component with such a part |
| KR100436581B1 (en) * | 2001-11-10 | 2004-06-19 | 엘지전선 주식회사 | PTC Device Manufacturing Method With Ingredient Of Uniform Specific Property |
| KR100436579B1 (en) * | 2001-11-10 | 2004-06-19 | 엘지전선 주식회사 | PTC Device Manufacturing Method With Excellent Resistance Repair Specific Property And PTC Device Thereof |
| KR100436580B1 (en) * | 2001-11-10 | 2004-06-19 | 엘지전선 주식회사 | PTC Device Manufacturing Method With Ingredient Of Excellent Resistance Repair Specific Property |
| KR100436578B1 (en) * | 2001-11-10 | 2004-06-19 | 엘지전선 주식회사 | PTC Device Manufacturing Method For Lithium Ion Battery Protecting And A PTC Device For Lithium Ion Battery Protecting Thereof |
| US7477131B2 (en) * | 2006-09-07 | 2009-01-13 | E.I. Du Pont De Nemours | Low temperature coefficient of resistivity polymeric resistors based on metal carbides and nitrides |
| US20090027821A1 (en) * | 2007-07-26 | 2009-01-29 | Littelfuse, Inc. | Integrated thermistor and metallic element device and method |
| JP2009203441A (en) * | 2008-02-29 | 2009-09-10 | Denso Corp | Composite material, manufacturing method therefor, and composite structure |
| CN102924776B (en) * | 2011-08-10 | 2015-10-28 | 富致科技股份有限公司 | PTC material composition and the overcurrent protection assembly be made up of it |
| CN102644131B (en) * | 2012-04-16 | 2013-12-04 | 夏华松 | Boron carbide high-polymer fiber |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE396182B (en) * | 1973-05-30 | 1977-09-05 | Philips Nv | SYNCHRONIZATION DEVICE |
| US3993602A (en) * | 1975-11-17 | 1976-11-23 | General Electric Company | Polycrystalline silicon carbide with increased conductivity |
| US4534889A (en) * | 1976-10-15 | 1985-08-13 | Raychem Corporation | PTC Compositions and devices comprising them |
| FR2368127A1 (en) * | 1976-10-15 | 1978-05-12 | Raychem Corp | COMPOSITIONS WITH A POSITIVE TEMPERATURE COEFFICIENT AND DEVICES INCLUDING |
| US4209474A (en) * | 1977-08-31 | 1980-06-24 | General Electric Company | Process for preparing semiconducting silicon carbide sintered body |
| US4271045A (en) * | 1978-06-13 | 1981-06-02 | Steigerwald Wolf Erhard | Electrically conductive layer and method for its production |
| US4545926A (en) * | 1980-04-21 | 1985-10-08 | Raychem Corporation | Conductive polymer compositions and devices |
| JPS5610352A (en) * | 1980-06-30 | 1981-02-02 | Jitsuo Kido | Heavy liquid overflow skimming type centrifugal separator |
| GB2111071B (en) * | 1981-09-16 | 1985-04-03 | Mitsubishi Petrochemical Co | Moldable composition containing propylene polymer |
| JPS58209084A (en) * | 1982-05-28 | 1983-12-05 | 株式会社日立製作所 | Direct heater heater material |
| SE433999B (en) * | 1982-11-12 | 1984-06-25 | Wolfgang Bronnvall | SELF-LIMITED ELECTRICAL HEATING DEVICE AND ELECTRIC RESISTANCE MATERIAL |
| JPS59122524A (en) * | 1982-12-28 | 1984-07-16 | Matsushita Electric Works Ltd | Composition having positive temperature characteristics of resistance |
| JPS60254586A (en) * | 1984-05-30 | 1985-12-16 | 株式会社デンソー | Ceramic heater |
| JPS61250058A (en) * | 1985-04-27 | 1986-11-07 | Showa Electric Wire & Cable Co Ltd | Organic conductive composition with ptc characteristics |
-
1985
- 1985-12-03 JP JP60270700A patent/JPS62131065A/en active Granted
-
1986
- 1986-11-24 US US06/934,495 patent/US4732701A/en not_active Expired - Fee Related
- 1986-12-01 DE DE8686116686T patent/DE3687062T2/en not_active Expired - Fee Related
- 1986-12-01 EP EP86116686A patent/EP0224903B1/en not_active Expired - Lifetime
- 1986-12-02 CA CA000524339A patent/CA1301986C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0474383B2 (en) | 1992-11-26 |
| EP0224903A3 (en) | 1988-08-31 |
| JPS62131065A (en) | 1987-06-13 |
| DE3687062T2 (en) | 1993-03-18 |
| EP0224903A2 (en) | 1987-06-10 |
| US4732701A (en) | 1988-03-22 |
| EP0224903B1 (en) | 1992-11-04 |
| DE3687062D1 (en) | 1992-12-10 |
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