EP0435923B1 - Conductive polymer composition - Google Patents
Conductive polymer composition Download PDFInfo
- Publication number
- EP0435923B1 EP0435923B1 EP89910755A EP89910755A EP0435923B1 EP 0435923 B1 EP0435923 B1 EP 0435923B1 EP 89910755 A EP89910755 A EP 89910755A EP 89910755 A EP89910755 A EP 89910755A EP 0435923 B1 EP0435923 B1 EP 0435923B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- carbon black
- conductive polymer
- less
- heater according
- ptc element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- 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
-
- 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
Definitions
- This invention relates to electrical heaters containing PTC conductive polymer compositions.
- Conductive polymer compositions which exhibit PTC (positive temperature coefficient of resistance) behavior are well-known and are particularly useful for self-regulating strip heaters and circuit protection devices.
- Conductive polymer compositions generally contain a crystalline polymer matrix and a carbon black dispersed in the matrix. Carbon blacks vary in particle size, surface area, structure, and surface chemistry, all of which influence the properties, e.g. flexibility and conductivity, of conductive polymers containing them.
- the surface chemistry of a carbon black can be altered by heat or chemical treatment, either during the production of the carbon black or in a post-production process, e.g. by oxidation. Oxidized carbon blacks frequently have a pH less than 5.0, and a high resistivity.
- Carbon blacks having low resistivity are generally used to make PTC conductive polymers -- see for example U.S. Patent Nos. 4,237,441 (van Konynenburg et al.) and 4,388,607 (Toy et al.).
- U.S. Patent No. 4,277,673 discloses self-regulating heaters in which the PTC conductive polymer comprises a highly resistive carbon black.
- Kelly uses a process to make self-regulating heaters, in which a PTC composition which comprises an organic fluoropolymer matrix which has a crystallinity of at least 5%, and at least 4% by weight of the composition of a carbon black having a pH of less than 4 is melt extruded as a strip around a pair of wire electrodes, and the extrudate is then annealed (i.e. held at a temperature above the melting point of the polymer) for an extended time.
- the conductive polymer as initially extruded, has a very high resistivity, and the annealing is necessary in order to reduce the resistivity to a useable level.
- conductive polymers containing highly resistive carbon blacks anneal more rapidly than conductive polymers in which only conductive carbon blacks are present.
- Conductive polymers are usually shaped by melt extrusion. Thin layers of conductive polymers can also be produced by solvent-based processes, and the resulting products have relatively low resistivity but suffer from poor stability.
- laminar conductive polymer heaters having good stability can be made through the use of thick film inks containing a crystalline fluoropolymer and a carbon black having a pH of less than 4.0. Accordingly, this invention provides an electrical heater which
- the conductive polymer composition in the heaters of the invention exhibits PTC behavior in the operating temperature range of the heater, i.e. it has an R 14 value of at least 2.5 or an R 100 value of at least 10 (and preferably both), and preferably also has an R 30 value of at least 6, where R 14 is the ratio of the resistivities at the end and the beginning of a 14°C range, R 100 is the ratio of the resistivities at the end and the beginning of a 100°C range, and R 30 is the ratio of the resistivities at the end and the beginning of a 30°C range.
- a composition having "ZTC" character increases in resistivity by less than 6 times, preferably less than 2 times, in any 30°C temperature range within the operating range of the heater.
- the carbon blacks used in this invention have a pH less than 4.0, preferably less than 3.0, measured prior to mixing with the polymer.
- a carbon black generally has a relatively high volatile content, i.e. a high amount of oxygen chemisorbed on its surface. The amount of oxygen can be increased by oxidation in a post-production process. The resulting carbon black will have a higher surface activity.
- Particularly preferred are carbon blacks having a ratio of resistivity (in ohm-cm) to particle size (in nanometers) less than or equal to 0.1, preferably less than or equal to 0.09, particularly less than or equal to 0.08. The resistivity is determined by the procedure described in Columbian Chemicals Company bulletin "The Dry Resistivity of Carbon Blacks" (AD1078).
- nonoxidized carbon blacks may be treated, e.g. by heat or appropriate oxidizing agents, to produce carbon blacks with appropriate surface chemistry.
- conductive fillers may be used in combination with the low pH carbon black.
- These fillers may comprise nonoxidized carbon black (i.e. a carbon black with a pH of at least 5.0), graphite, metal, metal oxide, or any combination of these.
- the low pH carbon black is present in amount at least 5%, preferably at least 10%, particularly at least 20%, e.g. 25 to 100%, by weight of the total conductive filler, and/or in amount at least 5%, preferably at least 6%, particularly at least 8%, by weight of the solid components of the total composition.
- the fluoropolymers used in this invention have a crystallinity of at least 5%, preferably at least 10%, particularly at least 15%, e.g. 20 to 30%.
- Suitable polymers include polyvinylidene fluoride, ethylene/tetrafluoroethylene copolymers, and terpolymers of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene; and blends of two or more such polymers.
- fluoropolymer is used herein to denote a polymer which contains at least 10%, preferably at least 25%, by weight of fluorine, or a mixture of two or more such polymers.
- the blend In order to achieve specific physical or thermal properties for some applications, it may be desirable to blend one crystalline polymer with another polymer, either crystalline or amorphous. When there are two or more polymers in the composition, the blend must have a crystallinity or at least 5%.
- the crystallinity, as well as the melting point T m are determined from a DSC (differential scanning calorimeter) trace on the conductive polymer composition.
- the T m is defined as the temperature at the peak of the melting curve. If the composition comprises a blend of two or more polymers, T m is defined as the lowest melting point measured for the composition (often corresponding to the melting point of the lowest melting component).
- the composition may comprise additional components, e.g. inert fillers, antioxidants, flame retardants, prorads, stabilizers, dispersing agents. Mixing is preferably conducted by solvent-blending.
- the composition may be crosslinked by irradiation or chemical means.
- the resistivity of the conductive polymer composition depends on the function of the heater, the dimensions of the PTC element, and the power source to be used.
- the resistivity may be, for example, 10 to 1000 ohm-cm for heaters powered at 6 to 60 volts, or 1000 to 10,000 ohm-cm or higher for heaters powered at voltages of at least 110 volts.
- the laminar PTC element may be of any shape to meet the requirements of the heater, and may be screenprinted or applied in any suitable configuration.
- the electrodes are in the form of metal sheet or conductive (e.g. metal- or carbon-filled) paint.
- the heaters of the invention show improved stability under thermal aging and electrical stress.
- the resistance at 20°C measured after aging i.e. R f50
- the resistance at 20°C measured after aging is from 0.25 R i to 1.75 R i , preferably from 0.40 R i to 1.60 R i , particularly from 0.50 R i to 1.50 R i , where R i is the initial resistance at 20°C.
- the resistance at 20°C after 300 hours, R f300 is generally from 0.50 R i to 1.50 R i , preferably from 0.60 R i to 1.40 R i , particularly from 0.70 R i to 1.30 R i . It is to be understood that if a heater meets the resistance requirement when tested at a temperature greater than T m , it will also meet the requirement when tested at T m . Similar results will be observed when the heater is actively powered by the application of voltage. The change in resistance may reflect an increase or decrease in heater resistance. In some cases, the resistance will first decrease and then increase during the test, possibly reflecting a relaxation of mechanically-induced stresses followed by oxidation of the polymer. Particularly preferred compositions may exhibit stability which is better than a 30% change in resistance.
- the invention is illustrated by the following examples, some of which are comparative examples, as indicated by an asterisk *.
- an ink was prepared by blending the designated percent by weight (of solids) of the appropriate carbon black with dimethyl formamide in a high shear mixer.
- the solution was the filtered and powdered KynarTM 9301 (a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene with a melting point of about 88°C, available from Pennwalt) in amount equal to (100 - % carbon black) was added to the filtrate and allowed to dissolve over a period of 24 to 72 hours. (Approximately 60% solvent and 40% solids was used in making the ink).
- ElectrodeagTM 461SS available from Acheson Colloids
- Samples of each ink were aged in ovens at temperatures of 65, 85, 107 and 149°C. Periodically, the samples were removed from the oven and the resistance at room temperature (nominally 20°C), R t , was measured. Normalized resistance, R n , was determined by dividing R t by the initial room temperature resistance, R i . The extent of instability was determined by the difference between R n and 1.00.
- Those inks which comprised carbon blacks with a pH of less than 4 were generally more stable than the inks comprising higher pH blacks.
- inks were prepared using KynarTM 9301 as a binder and incorporating the carbon blacks listed in Table IV.
- the resistance vs. Temperature characteristics were measured by exposing samples of each ink to a temperature cycle from 20°C to 82°C.
- the height of the PTC anomaly was determined by dividing the resistance at 82°C (R 82 ) by the resistance at 20°C (R 20 ). It was apparent that at comparable resistivity values, the PTC anomaly was higher for the low pH carbon blacks than for the high pH carbon blacks.
- DBP is a measure of the structure of the carbon black and is determined by measuring the amount in cubic centimeters of dibutyl phthalate absorbed by 100 g of carbon black.
- Wt% represents the percent by weight of the total solids content of the ink that is carbon black.
- Rho is the resistivity of the ink in ohm-cm.
- PTC Height is the height of the PTC anomaly as determined by R 82 /R 20 .
- R CB is the dry resistivity of the carbon black in powder form under a 5 kg load.
- R CB /D is the ratio of the dry resistivity of the carbon black to the particle size.
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Ceramic Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Conductive Materials (AREA)
- Thermistors And Varistors (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
Abstract
Description
- This invention relates to electrical heaters containing PTC conductive polymer compositions.
- Conductive polymer compositions which exhibit PTC (positive temperature coefficient of resistance) behavior are well-known and are particularly useful for self-regulating strip heaters and circuit protection devices. Reference may be made for example, to U.S. patent Nos. 3,793,716, 3, 823,217, 3,858,144, 3,861,029, 3,914,363, 4,017,715, 4,177,376, 4,188,276, 4,237,441, 4,242,573, 4,246,468, 4,286,376, 4,304,987, 4,318,881, 4,330,703, 4,334,148, 4,334,351, 4,388,607, 4,400,614, 4,425,497, 4,426,339, 4,435,639, 4,459,473, 4,514,620, 4,520,417, 4,529,866, 4,534,889, 4,543,474, 4,545,926, 4,547,659, 4,560,498, 4,571,481, 4,574,188, 4,582,983, 4,631,392, 4,638,150, 4,654,511, 4,658,121, 4,659,913, 4,661,687, 4,667,194, 4,673,801, 4,698,583, 4,719,335, 4,722,758, and 4,761,541, European Patent Publication Nos. 38,718 (Fouts et al., published October 28, 1981), 158,410 (Batliwalla et al., published October 16, 1985), and 231,068 (Barma et al, published August 5, 1989). Conductive polymer compositions generally contain a crystalline polymer matrix and a carbon black dispersed in the matrix. Carbon blacks vary in particle size, surface area, structure, and surface chemistry, all of which influence the properties, e.g. flexibility and conductivity, of conductive polymers containing them. The surface chemistry of a carbon black can be altered by heat or chemical treatment, either during the production of the carbon black or in a post-production process, e.g. by oxidation. Oxidized carbon blacks frequently have a pH less than 5.0, and a high resistivity.
- Carbon blacks having low resistivity are generally used to make PTC conductive polymers -- see for example U.S. Patent Nos. 4,237,441 (van Konynenburg et al.) and 4,388,607 (Toy et al.). However, U.S. Patent No. 4,277,673 (Kelly) discloses self-regulating heaters in which the PTC conductive polymer comprises a highly resistive carbon black. Kelly uses a process to make self-regulating heaters, in which a PTC composition which comprises an organic fluoropolymer matrix which has a crystallinity of at least 5%, and at least 4% by weight of the composition of a carbon black having a pH of less than 4 is melt extruded as a strip around a pair of wire electrodes, and the extrudate is then annealed (i.e. held at a temperature above the melting point of the polymer) for an extended time. The conductive polymer, as initially extruded, has a very high resistivity, and the annealing is necessary in order to reduce the resistivity to a useable level. According to Kelly, conductive polymers containing highly resistive carbon blacks anneal more rapidly than conductive polymers in which only conductive carbon blacks are present.
- Conductive polymers are usually shaped by melt extrusion. Thin layers of conductive polymers can also be produced by solvent-based processes, and the resulting products have relatively low resistivity but suffer from poor stability.
- We have discovered that laminar conductive polymer heaters having good stability can be made through the use of thick film inks containing a crystalline fluoropolymer and a carbon black having a pH of less than 4.0. Accordingly, this invention provides an electrical heater which
- (I) comprises
- (A) a PTC element which is composed of a conductive polymer composition which (i) exhibits PTC behavior, (ii) has a resistivity of 10 to 10,000 ohm-cm, and (iii) comprises
- (a) an organic fluoropolymer matrix which has a crystallinity of at least 5% and a melting point Tm, and
- (b) at least 4% by weight of the composition of a carbon black which has a pH of less than 4.0; and
- (B) two electrodes which can be connected to a source of electrical power to pass current through the PTC element; and
- (A) a PTC element which is composed of a conductive polymer composition which (i) exhibits PTC behavior, (ii) has a resistivity of 10 to 10,000 ohm-cm, and (iii) comprises
- (II) is such that if it is maintained at Tm for 50 hours, and is then cooled to 20°C, it has a resistance at 20°C from 0.25 Ri to 1.75 Ri; wherein Ri is the initial resistance at 20°C;
- (III) the PTC element is a laminar element which has been prepared by applying a polymer thick film ink which comprises the organic fluoropolymer, the carbon black and a solvent; and
- (IV) the electrodes are metal sheet or conductive paint electrodes attached to the PTC element.
- The conductive polymer composition in the heaters of the invention exhibits PTC behavior in the operating temperature range of the heater, i.e. it has an R14 value of at least 2.5 or an R100 value of at least 10 (and preferably both), and preferably also has an R30 value of at least 6, where R14 is the ratio of the resistivities at the end and the beginning of a 14°C range, R100 is the ratio of the resistivities at the end and the beginning of a 100°C range, and R30 is the ratio of the resistivities at the end and the beginning of a 30°C range. By contrast, a composition having "ZTC" character increases in resistivity by less than 6 times, preferably less than 2 times, in any 30°C temperature range within the operating range of the heater.
- The carbon blacks used in this invention have a pH less than 4.0, preferably less than 3.0, measured prior to mixing with the polymer. Such a carbon black generally has a relatively high volatile content, i.e. a high amount of oxygen chemisorbed on its surface. The amount of oxygen can be increased by oxidation in a post-production process. The resulting carbon black will have a higher surface activity. Particularly preferred are carbon blacks having a ratio of resistivity (in ohm-cm) to particle size (in nanometers) less than or equal to 0.1, preferably less than or equal to 0.09, particularly less than or equal to 0.08. The resistivity is determined by the procedure described in Columbian Chemicals Company bulletin "The Dry Resistivity of Carbon Blacks" (AD1078). In this test, 3 grams of carbon black in powder form are placed inside a glass tube between two brass plungers. A 5 kg weight is used to compact the carbon black. The height of the compacted carbon black and the resistance in ohms between the brass plunger electrodes are noted, and the resistivity is calculated.
- Commercially available low pH carbon blacks can be used. Alternatively, nonoxidized carbon blacks may be treated, e.g. by heat or appropriate oxidizing agents, to produce carbon blacks with appropriate surface chemistry.
- Other conductive fillers may be used in combination with the low pH carbon black. These fillers may comprise nonoxidized carbon black (i.e. a carbon black with a pH of at least 5.0), graphite, metal, metal oxide, or any combination of these. Preferably the low pH carbon black is present in amount at least 5%, preferably at least 10%, particularly at least 20%, e.g. 25 to 100%, by weight of the total conductive filler, and/or in amount at least 5%, preferably at least 6%, particularly at least 8%, by weight of the solid components of the total composition.
- The fluoropolymers used in this invention have a crystallinity of at least 5%, preferably at least 10%, particularly at least 15%, e.g. 20 to 30%. Suitable polymers include polyvinylidene fluoride, ethylene/tetrafluoroethylene copolymers, and terpolymers of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene; and blends of two or more such polymers. The term "fluoropolymer" is used herein to denote a polymer which contains at least 10%, preferably at least 25%, by weight of fluorine, or a mixture of two or more such polymers. In order to achieve specific physical or thermal properties for some applications, it may be desirable to blend one crystalline polymer with another polymer, either crystalline or amorphous. When there are two or more polymers in the composition, the blend must have a crystallinity or at least 5%. The crystallinity, as well as the melting point Tm, are determined from a DSC (differential scanning calorimeter) trace on the conductive polymer composition. The Tm is defined as the temperature at the peak of the melting curve. If the composition comprises a blend of two or more polymers, Tm is defined as the lowest melting point measured for the composition (often corresponding to the melting point of the lowest melting component).
- The composition may comprise additional components, e.g. inert fillers, antioxidants, flame retardants, prorads, stabilizers, dispersing agents. Mixing is preferably conducted by solvent-blending. The composition may be crosslinked by irradiation or chemical means.
- The resistivity of the conductive polymer composition depends on the function of the heater, the dimensions of the PTC element, and the power source to be used. The resistivity may be, for example, 10 to 1000 ohm-cm for heaters powered at 6 to 60 volts, or 1000 to 10,000 ohm-cm or higher for heaters powered at voltages of at least 110 volts. The laminar PTC element may be of any shape to meet the requirements of the heater, and may be screenprinted or applied in any suitable configuration. The electrodes, are in the form of metal sheet or conductive (e.g. metal- or carbon-filled) paint.
- The heaters of the invention show improved stability under thermal aging and electrical stress. When a heater is maintained at a temperature equal to Tm for a period of 50 hours, the resistance at 20°C measured after aging, i.e. Rf50, is from 0.25 Ri to 1.75 Ri, preferably from 0.40 Ri to 1.60 Ri, particularly from 0.50 Ri to 1.50 Ri, where Ri is the initial resistance at 20°C. If a similar test is conducted for 300 hours, the resistance at 20°C after 300 hours, Rf300, is generally from 0.50 Ri to 1.50 Ri, preferably from 0.60 Ri to 1.40 Ri, particularly from 0.70 Ri to 1.30 Ri. It is to be understood that if a heater meets the resistance requirement when tested at a temperature greater than Tm, it will also meet the requirement when tested at Tm. Similar results will be observed when the heater is actively powered by the application of voltage. The change in resistance may reflect an increase or decrease in heater resistance. In some cases, the resistance will first decrease and then increase during the test, possibly reflecting a relaxation of mechanically-induced stresses followed by oxidation of the polymer. Particularly preferred compositions may exhibit stability which is better than a 30% change in resistance.
- The invention is illustrated by the following examples, some of which are comparative examples, as indicated by an asterisk *.
- For each example, an ink was prepared by blending the designated percent by weight (of solids) of the appropriate carbon black with dimethyl formamide in a high shear mixer. The solution was the filtered and powdered Kynar™ 9301 (a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene with a melting point of about 88°C, available from Pennwalt) in amount equal to (100 - % carbon black) was added to the filtrate and allowed to dissolve over a period of 24 to 72 hours. (Approximately 60% solvent and 40% solids was used in making the ink). Silver-based ink electrodes (Electrodag™ 461SS, available from Acheson Colloids) were printed onto ethylene-tetrafluoroethylene substrates and samples of each ink were applied. Samples of each ink were aged in ovens at temperatures of 65, 85, 107 and 149°C. Periodically, the samples were removed from the oven and the resistance at room temperature (nominally 20°C), Rt, was measured. Normalized resistance, Rn, was determined by dividing Rt by the initial room temperature resistance, Ri. The extent of instability was determined by the difference between Rn and 1.00. Those inks which comprised carbon blacks with a pH of less than 4 were generally more stable than the inks comprising higher pH blacks.
TABLE I Stability of Conductive Inks After Aging at Elevated Temperature for 300 Hours (Resistance Measured at Room Temperature) Carbon Example/Black pH Wt% CB Rn @ 65°C Rn @ 85°C Rn @ 107°C Rn @ 149°C *1 Conductex™ SC 7.0 3.0 1.22 1.75 5.61 6.39 *2 Raven™ 1500 6.0 3.0 1.01 1.92 11.88 20.0 *3 Raven™ 890 6.5 6.0 1.27 1.77 2.92 6.07 *4 Raven™ 850 7.0 4.0 1.32 2.05 4.08 8.48 *5 Raven™ 1000 6.0 4.0 1.18 1.43 1.94 4.40 *6 Raven™ 16 7.0 5.6 1.11 1.89 - - 7 Raven™ 5750 2.1 8.1 0.87 0.92 0.97 0.56 8 Raven™ 1040 2.8 9.1 0.96 1.15 1.47 1.34 9 Raven™ 1255 2.5 6.0 1.04 1.26 1.12 0.65 10 Raven™ 14 3.0 7.0 0.82 1.00 - - Notes to Table I:
(1) Conductex and Raven are trademarks for carbon blacks available from Columbian Chemicals.
(2) Wt% CB indicates the percent by weight of carbon black used in each ink.
(3) Carbon blacks in Examples 1, 2 and 3 produced inks with ZTC character. - Measurements on two samples at 93°C (i.e. Tm + 5°C) showed that after 50 hours Example 6 (pH = 7.0) had an Rn of 2.53 and Example 10 (pH 3.0) had an Rn of 1.48.
-
- Additional tests were conducted on samples from Examples 6 and 10 in order to determine the stability of the compositions under applied voltage. After measuring the initial room temperature resistance, the samples were placed in environmental chambers maintained at either 20 or 65°C and appropriate voltage was applied to each sample in order to produce comparable watt densities. Periodically, the voltage was disconnected and the resistance of each sample measured. Rn was calculated as previously described. It is apparent from the results in Table III that the samples containing the oxidized carbon black were more stable than those with nonoxidized carbon black.
- Following the procedure of Examples 1 to 10, inks were prepared using Kynar™ 9301 as a binder and incorporating the carbon blacks listed in Table IV. The resistance vs. Temperature characteristics were measured by exposing samples of each ink to a temperature cycle from 20°C to 82°C. The height of the PTC anomaly was determined by dividing the resistance at 82°C (R82) by the resistance at 20°C (R20). It was apparent that at comparable resistivity values, the PTC anomaly was higher for the low pH carbon blacks than for the high pH carbon blacks.
TABLE IV Carbon Example/Black pH D (nm) S.A. (m2/g) DBP (cc/100g) RCB (ohm-cm) RCB/D Wt% Rho (ohm-cm) PTC Height *11 Raven™ 1000 6.0 28 95 63 2.46 0.088 4.0 750 3.1x 12 Raven™ 1040 2.8 28 90 99 19.20 0.695 9.1 720 13.0x *13 Raven™ 450 8.0 62 33 67 1.36 0.021 5.0 150 23x 14 Raven™ 14 3.0 59 45 111 4.36 0.074 12.0 100 42x Notes to Table IV:
(1) D represents the particle size of the carbon black in nm.
(2) S.A. represents the surface area of the carbon black in m2/g as measured by a BET nitrogen test.
(3) DBP is a measure of the structure of the carbon black and is determined by measuring the amount in cubic centimeters of dibutyl phthalate absorbed by 100 g of carbon black.
(4) Wt% represents the percent by weight of the total solids content of the ink that is carbon black.
(5) Rho is the resistivity of the ink in ohm-cm.
(6) PTC Height is the height of the PTC anomaly as determined by R82/R20.
(7) RCB is the dry resistivity of the carbon black in powder form under a 5 kg load.
(8) RCB/D is the ratio of the dry resistivity of the carbon black to the particle size.
Claims (7)
- An electrical heater which(I) comprises(A) a PTC element which is composed of a conductive polymer composition which (i) exhibits PTC behavior, (ii) has a resistivity of 10 to 10,000 ohm-cm, and (iii) comprises(a) an organic fluoropolymer matrix which has a crystallinity of at least 5% and a melting point Tm, and(b) at least 4% by weight of the composition of a carbon black which has a pH of less than 4.0; and(B) two electrodes which can be connected to a source of electrical power to pass current through the PTC element;(II) is such that if it is maintained at Tm for 50 hours, and is then cooled to 20°C, it has a resistance at 20°C from 0.25 Ri to 1.75 Ri; wherein Ri is the initial resistance at 20°C;characterized in that(III) the PTC element is a laminar element which has been prepared by applying a polymer thick film ink which comprises the organic fluoropolymer, the carbon black and a solvent; and(IV) the electrodes are metal sheet or conductive paint electrodes attached to the PTC element.
- A heater according to claim 1 characterized in that the PTC element has been prepared by screen printing the polymer thick film ink.
- A heater according to claim 1 or 2, characterized in that the carbon black having a pH of less than 4.0 is the sole conductive filler in the conductive polymer composition.
- A heater according to any one of the preceding claims characterized in that the carbon black has a pH of less than 3.0.
- A heater according to any one of the preceding claims, characterized in that the composition further comprises (i) carbon black which has a pH which is at least 5.0 or (ii) graphite.
- A heater according to any one of the preceding claims characterized in that the carbon black has a particle size of D nanometers and a dry resistivity RCB such that (RCB/D) is less than or equal to 0.1.
- A heater according to any one of the preceding claims characterized in that the conductive polymer has been crosslinked.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97201655A EP0803879B1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US24705988A | 1988-09-20 | 1988-09-20 | |
US247059 | 1988-09-20 | ||
PCT/US1989/004010 WO1990003651A1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97201655A Division EP0803879B1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
EP97201655.4 Division-Into | 1997-06-03 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0435923A1 EP0435923A1 (en) | 1991-07-10 |
EP0435923B1 true EP0435923B1 (en) | 1997-12-17 |
Family
ID=22933384
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97201655A Expired - Lifetime EP0803879B1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
EP89910755A Expired - Lifetime EP0435923B1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97201655A Expired - Lifetime EP0803879B1 (en) | 1988-09-20 | 1989-09-15 | Conductive polymer composition |
Country Status (8)
Country | Link |
---|---|
EP (2) | EP0803879B1 (en) |
JP (2) | JP2876549B2 (en) |
KR (1) | KR100224945B1 (en) |
AT (2) | ATE161354T1 (en) |
CA (1) | CA1334480C (en) |
DE (2) | DE68929517T2 (en) |
HK (1) | HK1021613A1 (en) |
WO (1) | WO1990003651A1 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1267672B1 (en) * | 1994-01-17 | 1997-02-07 | Hydor Srl | THERMAL SENSITIVE RESISTIVE COMPOUND, ITS METHOD OF REALIZATION AND USE |
DE10310722A1 (en) | 2003-03-10 | 2004-09-23 | Tesa Ag | Electrically heatable adhesive composition, useful for adhesive tape in automotive applications such as electrically heated mirrors, comprises an adhesive component and an electrically conductive filler |
DE102007007617A1 (en) | 2007-02-13 | 2008-08-14 | Tesa Ag | Intrinsically heatable hot melt tacky fabrics |
DE102008034748A1 (en) | 2008-07-24 | 2010-01-28 | Tesa Se | Flexible heated surface element |
DE102008063849A1 (en) | 2008-12-19 | 2010-06-24 | Tesa Se | Heated surface element and method for its attachment |
DE102009010437A1 (en) | 2009-02-26 | 2010-09-02 | Tesa Se | Heated surface element |
US20130193384A1 (en) * | 2012-01-31 | 2013-08-01 | E. I. Du Pont De Nemours And Company | Polymer thick film positive temperature coefficient carbon composition |
JP7309444B2 (en) * | 2018-07-05 | 2023-07-18 | キヤノン株式会社 | RESIN COMPOSITION, RESIN MOLDED PRODUCT, RESIN LAMINATED BODY, CARTRIDGE, IMAGE FORMING APPARATUS, METHOD FOR MANUFACTURING RESIN MOLDED BODY, METHOD FOR MANUFACTURING RESIN LAMINATED BODY, AND METHOD FOR MANUFACTURING CARTRIDGE |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4237441A (en) * | 1978-12-01 | 1980-12-02 | Raychem Corporation | Low resistivity PTC compositions |
US4277673A (en) * | 1979-03-26 | 1981-07-07 | E-B Industries, Inc. | Electrically conductive self-regulating article |
US4591700A (en) * | 1980-05-19 | 1986-05-27 | Raychem Corporation | PTC compositions |
EP0123540A3 (en) * | 1983-04-20 | 1985-01-02 | RAYCHEM CORPORATION (a California corporation) | Conductive polymers and devices containing them |
US4668857A (en) * | 1985-08-16 | 1987-05-26 | Belton Corporation | Temperature self-regulating resistive heating element |
AU589714B2 (en) * | 1985-12-06 | 1989-10-19 | Sunbeam Corp. | PTC compositions containing a non-surface treated carbon black having an intermediate resistivity for reduced annealing |
-
1989
- 1989-09-15 KR KR1019900701040A patent/KR100224945B1/en not_active IP Right Cessation
- 1989-09-15 DE DE68929517T patent/DE68929517T2/en not_active Expired - Lifetime
- 1989-09-15 AT AT89910755T patent/ATE161354T1/en not_active IP Right Cessation
- 1989-09-15 DE DE68928502T patent/DE68928502T2/en not_active Expired - Fee Related
- 1989-09-15 JP JP1510152A patent/JP2876549B2/en not_active Expired - Lifetime
- 1989-09-15 AT AT97201655T patent/ATE262725T1/en not_active IP Right Cessation
- 1989-09-15 EP EP97201655A patent/EP0803879B1/en not_active Expired - Lifetime
- 1989-09-15 EP EP89910755A patent/EP0435923B1/en not_active Expired - Lifetime
- 1989-09-15 WO PCT/US1989/004010 patent/WO1990003651A1/en active IP Right Grant
- 1989-09-19 CA CA000611894A patent/CA1334480C/en not_active Expired - Fee Related
-
1998
- 1998-08-12 JP JP10227984A patent/JP2955281B2/en not_active Expired - Fee Related
- 1998-12-21 HK HK98114530A patent/HK1021613A1/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
DE68928502T2 (en) | 1998-06-18 |
ATE262725T1 (en) | 2004-04-15 |
DE68928502D1 (en) | 1998-01-29 |
DE68929517T2 (en) | 2005-02-03 |
JPH11144907A (en) | 1999-05-28 |
KR100224945B1 (en) | 1999-10-15 |
JP2876549B2 (en) | 1999-03-31 |
HK1021613A1 (en) | 2000-06-16 |
EP0803879A1 (en) | 1997-10-29 |
JP2955281B2 (en) | 1999-10-04 |
EP0435923A1 (en) | 1991-07-10 |
KR900702544A (en) | 1990-12-07 |
EP0803879B1 (en) | 2004-03-24 |
DE68929517D1 (en) | 2004-04-29 |
WO1990003651A1 (en) | 1990-04-05 |
JPH04500745A (en) | 1992-02-06 |
ATE161354T1 (en) | 1998-01-15 |
CA1334480C (en) | 1995-02-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4980541A (en) | Conductive polymer composition | |
US5181006A (en) | Method of making an electrical device comprising a conductive polymer composition | |
EP0435941B1 (en) | Conductive polymer composition | |
JP3930905B2 (en) | Conductive polymer composition and device | |
EP0217512B1 (en) | Polymer thick film inks | |
US4388607A (en) | Conductive polymer compositions, and to devices comprising such compositions | |
US6221282B1 (en) | Electrical devices comprising conductive polymer compositions | |
EP0706708B1 (en) | Circuit protection device | |
JP3558771B2 (en) | Positive temperature coefficient composition | |
JPH0159684B2 (en) | ||
EP0435923B1 (en) | Conductive polymer composition | |
US20170327707A1 (en) | Electrically Conductive PTC Screen Printable Ink with Double Switching Temperatures and Method of Making the Same | |
CA1104808A (en) | Conductive polymer compositions | |
CA1133085A (en) | Temperature sensitive electrical device | |
JPS6034792B2 (en) | heating element | |
EP0522228A1 (en) | Electric heater |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19910316 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE FR GB IT LI NL SE |
|
17Q | First examination report despatched |
Effective date: 19930617 |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE CH DE FR GB IT LI NL SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19971217 Ref country code: LI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19971217 Ref country code: CH Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19971217 Ref country code: BE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19971217 Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19971217 |
|
REF | Corresponds to: |
Ref document number: 161354 Country of ref document: AT Date of ref document: 19980115 Kind code of ref document: T |
|
XX | Miscellaneous (additional remarks) |
Free format text: TEILANMELDUNG 97201655.4 EINGEREICHT AM 03/06/97. |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
REF | Corresponds to: |
Ref document number: 68928502 Country of ref document: DE Date of ref document: 19980129 |
|
ITF | It: translation for a ep patent filed |
Owner name: MODIANO & ASSOCIATI S.R.L. |
|
ET | Fr: translation filed | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19980317 |
|
NLV1 | Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act | ||
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20030314 Year of fee payment: 14 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20030317 Year of fee payment: 14 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20030915 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20030925 Year of fee payment: 15 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040401 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20030915 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20050531 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED. Effective date: 20050915 |