EP0121289A1 - Dispositif électrique à coefficient de température négatif - Google Patents

Dispositif électrique à coefficient de température négatif Download PDF

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Publication number
EP0121289A1
EP0121289A1 EP19840300084 EP84300084A EP0121289A1 EP 0121289 A1 EP0121289 A1 EP 0121289A1 EP 19840300084 EP19840300084 EP 19840300084 EP 84300084 A EP84300084 A EP 84300084A EP 0121289 A1 EP0121289 A1 EP 0121289A1
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EP
European Patent Office
Prior art keywords
pyrrole
substituted
substituent
electrically conductive
lower alkyl
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.)
Withdrawn
Application number
EP19840300084
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German (de)
English (en)
Inventor
Stephen Baigrie
Robert Lines
Judith Hardy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raychem Ltd
Original Assignee
Raychem Ltd
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Filing date
Publication date
Application filed by Raychem Ltd filed Critical Raychem Ltd
Publication of EP0121289A1 publication Critical patent/EP0121289A1/fr
Withdrawn legal-status Critical Current

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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
    • H01C7/04—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 negative temperature coefficient
    • H01C7/049—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 negative temperature coefficient mainly consisting of organic or organo-metal substances

Definitions

  • NTC negative temperature coefficient
  • thermistors may be made from the oxides of such materials as iron, chromium, manganese, cobalt and nickel doped by the addition of small quantities of a metal with a different valency.
  • the invention provides an NTC electrical device having as an NTC element an electrically conductive material produced by oxidative doping of a 2-substituted pyrrole.
  • electrically conductive materials can be produced by oxidation of pyrrole which results in the formation of an electrically charged polymer or oligomer inherently capable of conducting electricity.
  • a negative counter-ion is required to balance the positive electrical charge on the oxidised electrically conductive pyrrole material.
  • This counter-ion will be hereinafter referred to as a "dopant”, and the process of oxidation and introduction of the dopant will be referred to as "oxidative doping", regardless of whether the doping is performed together with, or after, the oxidation.
  • dopants include BF 4 , Br-, p-toluenesulphonate.
  • the preferred 2-substituents are electron-releasing groups, preferably lower alkyl groups, especially methyl, although other (more expensive) substituents may be useful. Further substitution in the 3-, 4- or 5- positions of the pyrrole also produces high negative temperature coefficients compared with 3,4-disubstitution or unsubstituted pyrrole, the preferred 3-, 4-, or 5-substituents also being electron-donating groups, preferably lower alkyl groups, especially methyl.
  • Electrically conductive materials produced from pyrroles tend to have advantageous oxidation resistance over other conductive polymers such as polyacetylenes. To obtain a conductive polymer, sufficient positions must be left unsubstituted to permit polymerisation. Electrically conductive polymers are generally believed to operate by way of a conjugated pi-electron system, and it will be understood that some substituents or combinations of substituents may interfere with the conjugated system so as to detract from or destroy the desired electrical conductivity, acceptable substituents being readily determinable by simply testing the conductivity of the resulting polymer. It is however not essential that the conductive material be a true polymer or oligomer, provided that it displays the required NTC effect.
  • oxidative doping of 2,5-dimethyl pyrrole can produce a black powder which is not readily identifiable as a polymer, but has the strong NTC effect aforementioned.
  • the products of oxidative doping of 2,3-dimethyl pyrrole, 2,4-dimethyl pyrrole and 2-methyl pyrrole have the aforementioned NTC effect are believed to be new materials which are accordingly claimed per se together with their lower alkyl homologues as part of the present invention.
  • the 2-substituted pyrrole and the dopant are mixed with an oxidising agent in a suitable liquid vehicle.
  • the oxidising agent can advantageously be carried by the dopant, for example by forming the ferric salt of a dopant such as p-toluenesulphonate or halide ions, thereby bringing about simultaneous oxidative polymerisation and doping with the negatively charged dopant.
  • Some oxidation reactions tend to produce an insoluble product, which is relatively non-conductive, and a soluble product which, alone or in a mixture with the insoluble product, displays the marked NTC behaviour on which the present invention is based.
  • 2,5-dimethyl pyrrole is commercially available.
  • the remaining methyl pyrroles: 2-methyl; 2,3-dimethyl; 2,4-dimethyl and 3,4-dimethyl were synthesised by known literature methods.
  • methyl pyrroles can be oxidised by metal salt oxidants such as ferric perchlorate to brown or black conductive powders. With the exception of 2,5-dimethyl pyrrole, chlorine can also be used to oxidise the methyl pyrroles.
  • Example 2 was repeated substituting 2-methyl pyrrole for the 2,4-dimethylpyrrole.
  • Example 2 was repeated substituting 2,3-dimethylpyrrole for the 2,4-dimethylpyrrole.
  • the pyrrole samples were compressed into pellets 1.3cm diameter using a SPECAC Powder Jig.
  • the powder was preheated in the jig to about 140°C then loaded under pressure (ca. 40 kgcm ) for 5 minutes.
  • the compressed sample was removed, checked for quality, and measured on a digital multimeter by locating the pellet between spring-loaded circular copper electrodes in a 2 probe configuration.
  • Conductivity vs. temperature curves were obtained by placing the device in a temperature programmable oven. The results are shown in the accompanying drawing.
  • NTC effect of oxidatively doped 2-methyl pyrrole, 2,4-dimethyl pyrrole and 2,5-dimethyl pyrrole is shown graphically compared with the very much less significant NTC effect of oxidatively doped 3,4-dimethyl pyrrole.
  • Unsubstituted pyrrole produces a substantially zero temperature coefficient, which could be plotted as a substantially horizontal line on this graph.
  • mixtures of the 2-substituted pyrroles may be advantageous to use mixtures of the 2-substituted pyrroles with one another or with other pyrroles.
  • oxidative doping of a mixture of a 2-substituted pyrrole with unsubstituted pyrrole has been found to achieve an NTC effect comparable with that of the 2-substituted pyrrole itself, while considerably raising the conductivity (lowering the resistivity) of the resulting material.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Polyoxymethylene Polymers And Polymers With Carbon-To-Carbon Bonds (AREA)
  • Thermistors And Varistors (AREA)
EP19840300084 1983-01-07 1984-01-06 Dispositif électrique à coefficient de température négatif Withdrawn EP0121289A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838300352A GB8300352D0 (en) 1983-01-07 1983-01-07 Ntc electrical device
GB8300352 1983-01-07

Publications (1)

Publication Number Publication Date
EP0121289A1 true EP0121289A1 (fr) 1984-10-10

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840300084 Withdrawn EP0121289A1 (fr) 1983-01-07 1984-01-06 Dispositif électrique à coefficient de température négatif

Country Status (4)

Country Link
EP (1) EP0121289A1 (fr)
JP (1) JPS59135704A (fr)
CA (1) CA1200614A (fr)
GB (1) GB8300352D0 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7161463B2 (en) 2001-12-14 2007-01-09 Shin-Etsu Polymer Co., Ltd. Organic NTC composition, organic NTC device and production method of the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0618863B2 (ja) * 1986-03-28 1994-03-16 三菱化成株式会社 有機半導体

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3574072A (en) * 1968-04-03 1971-04-06 Universal Oil Prod Co Polymerization of heterocyclic compounds
EP0037924A2 (fr) * 1980-04-11 1981-10-21 BASF Aktiengesellschaft Procédé de préparation de polycondensats électriquement conducteurs et leur utilisation dans le domaine électrotechnique et comme additifs antistatiques pour des matériaux plastiques
EP0055358A1 (fr) * 1980-12-31 1982-07-07 BASF Aktiengesellschaft Dérivés électro-conducteurs de polypyrrole

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3574072A (en) * 1968-04-03 1971-04-06 Universal Oil Prod Co Polymerization of heterocyclic compounds
EP0037924A2 (fr) * 1980-04-11 1981-10-21 BASF Aktiengesellschaft Procédé de préparation de polycondensats électriquement conducteurs et leur utilisation dans le domaine électrotechnique et comme additifs antistatiques pour des matériaux plastiques
EP0055358A1 (fr) * 1980-12-31 1982-07-07 BASF Aktiengesellschaft Dérivés électro-conducteurs de polypyrrole

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"ORGANIC CONDUCTORS", Emerging Technologies no. 8; Published by Technical Insights, Inc,; Fort Lee, N.J., October 1982 *pages 21-24* *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7161463B2 (en) 2001-12-14 2007-01-09 Shin-Etsu Polymer Co., Ltd. Organic NTC composition, organic NTC device and production method of the same

Also Published As

Publication number Publication date
GB8300352D0 (en) 1983-02-09
CA1200614A (fr) 1986-02-11
JPS59135704A (ja) 1984-08-04

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Inventor name: BAIGRIE, STEPHEN

Inventor name: HARDY, JUDITH

Inventor name: LINES, ROBERT