EP0063440A2 - Strahlungsvernetzung der PTC-leitfähigen Polymere - Google Patents

Strahlungsvernetzung der PTC-leitfähigen Polymere Download PDF

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Publication number
EP0063440A2
EP0063440A2 EP82301765A EP82301765A EP0063440A2 EP 0063440 A2 EP0063440 A2 EP 0063440A2 EP 82301765 A EP82301765 A EP 82301765A EP 82301765 A EP82301765 A EP 82301765A EP 0063440 A2 EP0063440 A2 EP 0063440A2
Authority
EP
European Patent Office
Prior art keywords
electrodes
mrads
ptc element
ptc
cross
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.)
Granted
Application number
EP82301765A
Other languages
English (en)
French (fr)
Other versions
EP0063440B1 (de
EP0063440A3 (en
Inventor
Stephen M. Jacobs
Mary Sandra Mctavish
James Michael Taylor
Frank Anthony Doljack
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 Corp
Original Assignee
Raychem Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from US06/254,352 external-priority patent/US4426633A/en
Application filed by Raychem Corp filed Critical Raychem Corp
Priority to AT82301765T priority Critical patent/ATE46982T1/de
Publication of EP0063440A2 publication Critical patent/EP0063440A2/de
Publication of EP0063440A3 publication Critical patent/EP0063440A3/en
Application granted granted Critical
Publication of EP0063440B1 publication Critical patent/EP0063440B1/de
Expired legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-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
    • H01C7/02Non-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
    • H01C7/027Non-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
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20Conductive material dispersed in non-conductive organic material
    • H01B1/24Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00Ohmic-resistance heating
    • H05B3/10Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material

Definitions

  • This invention relates to the radiation cross-linking of PTC conductive polymers.
  • OLS 2,634,999 recommends a dose of 20-45 Mrads
  • U.K. Specification No. 1,071,032 describes irradiated compositions comprising a copolymer of ethylene and a vinyl ester or an acrylate monomer and 50-400% by weight of a filler, e.g. carbon black, the radiation dose being about 2 to about 100 Mrads, preferably about 2 to about 20 Mrads, and the use of such compositions as tapes for grading the insulation on cables; and
  • U.S. Patent No. 3,351,882 discloses the preparation of electrical devices by embedding planar electrodes in a PT C conductive polymer element, and then cross-linking the conductive polymer by irradiating it to a dosage of 50 to 100 Mrads.
  • the invention provides a process for the preparation of an electrical device comprising (a) a cross-linked PTC conductive polymer element and (b) two electrodes which can be connected to a power source to cause current to flow through the PTC element, which process comprises cross-linking the PTC element by irradiating it to a dosage of at least 50 Mrads, subject to the proviso that if each of the electrodes has a substantially planar configuration, then either (a) the element is irradiated to a dosage of at least 120 Mrads, or (b) the electrodes are metal foil electrodes which are secured to the PTC element after it has been cross-linked.
  • the radiation dose is, therefore, preferably at least 60 Mrads, particularly at least 80 Mrads, with yet higher dosages, e.g. at least 120 Mrads or at least 160 Mrads, being preferred when satisfactory PTC characteristics are maintained and the desire for improved performance outweighs the cost of radiation.
  • This method involves the use of a scanning electron microscope (SEM) to measure the maximum rate at which the voltage changes in the PTC element when the device is in the tripped state. This maximum rate occurs in the so-called "hot zone" of the PTC element. The lower the maximum rate, the greater the number of trips that the device will withstand.
  • SEM scanning electron microscope
  • an electrical device which comprises (a) a radiation cross-linked PTC conductive polymer element and (b) two electrodes which can be connected to a power source to cause current to flow through the PTC element, said device, when subjected to SEM scanning (as hereinafter defined), showing a maximum difference in voltage between two points separated by 10 microns which is less than 4.2 volts, e.g. less than 4.0 volts, preferably less than 3.0 volts, particularly less than 2.0 volts, especially less than 1.0 volt, subject to the proviso that if each of the electrodes has a substantially planar configuration, the maximum difference is less than 3 volts.
  • SEM scanning is used herein to denote the following procedure.
  • the device is inspected to see whether the PTC element has an exposed clean surface which is suitable for scanning in an SEM and which lies between the electrodes. If there is no such surface, then one is created, keeping the alteration of the device to a minimum.
  • the device (or a portion of it if the device is too large, e.g. if it is an elongate heater) is then mounted in a scanning electron microscope so that the electron beam can be traversed from one electrode to the other and directed obliquely at the clean exposed surface.
  • a slowly increasing current is passed through the device, using a DC power source of 200 volts, until the device has been "tripped" and the whole of the potential dropped across it.
  • the electron beam is then traversed across the surface and, using voltage contrast techniques known to those skilled in the art, there is obtained a photomicrograph in which the trace is a measure of the brightness (and hence the potential) of the surface between the electrodes; such a photomicrograph is often known as a line scan.
  • a diagrammatic representation of a typical photomicrograph is shown in Figure 1. It will be seen that the trace has numerous small peaks and valleys and it is believed that these are due mainly or.exclusively to surface imperfections.
  • a single “best line” is drawn through the trace (the broken line in Figure 1) in order to average out small variations, and from this "best line", the maximum difference in voltage between two points separated by 10 microns is determined.
  • an electrode having a substantially planar configuration
  • each of the electrodes has a columnar shape.
  • Such a device is shown in isometric view in Figure 2, in which wire electrodes 2 are embedded in PTC conductive polymer element 1 having a hole through its centre portion.
  • circuit protection devices In a second class of devices, usually circuit protection devices,
  • cap electrodes 2 contact either end of cylindrical P TC conductive polymer element 1 having a hole 11 thorugh its centre portion.
  • each of the electrodes has a substantially planar configuration.
  • Meshed planar electrodes can be used, but metal foil electrodes are preferred. If metal foil electrodes are applied to the PTC element before it is irradiated, there is a danger that gases evolved during irradiation will be trapped. It is preferred, therefore, that metal foil electrodes be applied after the radiation cross-linking step.
  • a preferred process comprises the
  • PTC conductive polymers suitable for use in this invention are disclosed in the patents and applications referenced above. Their resistivity at 23°C is preferably less than 1250 ohm.cm, eg. less than 750 ohm.cm, particularly less than 500 ohm.cm, with values less than 50 ohm.cm being preferred for circuit protection devices.
  • the polymeric component should be one which is cross-linked and not significantly degraded by radiation.
  • the polymeric component is preferably free of thermosetting polymers and often consists essentially of one or more crystalline polymers. Suitable polymers include polyolefins, eg.
  • the conductive filler is preferably carbon black.
  • the composition may also contain a non-conductive filler, eg. alumina trihydrate.
  • the composition can, but preferably does not, contain a radiation cross-linking aid. The presence of a cross-linking aid can substantially reduce the radiation dose required to produce a particular degree of cross-linking, but its residue generally has an adverse effect on electrical characteristics.
  • Shaping of the conductive polymer will generally be effected by a melt-shaping technique, eg. by melt- extrusion or molding.
  • the ingredients for the masterbatch were dry blended and then mixed for 12 minutes in a Banbury mixer turning at high gear. The mixture was dumped, cooled, and granulated. The final mix was prepared by dry blending 948.3 g. of Hydral 705 with 2439.2 g. of the masterbatch, and then mixing the dry blend for 7 minutes in a Banbury mixer turning at high gear. The mixture was dumped, cooled, granulated, and then dried at 70°C and 1 torr for 16 hours.
  • the granulated final mix was melt extruded as a strip 1 cm: wide and 0.25 cm. thick, around three wires. Two of the wires were preheated 20 AWG (0.095 cm. diameter) 19/32-sttanded nickel-plated copper wires whose centers were 0.76 cm. apart, and the third wire, a 24 A W G (0.064 cm. diameter) solid nickel-plated copper wire, was centered between the other two. Portions 1 cm. long were cut from the extruded product and from each portion the polymeric composition was removed from about half the length, and the whole of the center 24 AWG wire was removed, leaving a hole running through the polymeric element.
  • the products were heat treated in nitrogen at 150°C for 30 minutes and then in air at 110°C for 60 minutes, and were then irradiated.
  • Samples were irradiated to dosages of 20 Mrads, 80 Mrads or 160 Mrads. These samples, when subjected to SEM scanning, were found to have a maximum difference in voltage between two points separated by 10 microns of about 5.2, about 4.0 and about 2.0 respectively. Some of these samples were then sealed inside a metal can, with a polypropylene envelope between the conductive element and the can.
  • the resulting circuit protection devices were tested to determine how many test cycles they would withstand when tested in a circuit consisting essentially of a 240 volt AC power supply, a switch, a fixed resistor and the device.
  • the devices had a resistance of 20-30 ohms at 23°C and the fixed resistor had a resistance of 33 ohms, so that when the power supply was first switched on, the initial current in the circuit was 4-5 amps.
  • Each test cycle consisted of closing the switch, thus tripping the device, and after a period of about 10 seconds, opening the switch and allowing the device to cool for 1 minute before the next test cycle.
  • the resistance of the device at 23°C was measured initially and after every fifth cycle.
  • the Table below shows the number of cycles needed to increase the resistance to 1-1/2 times its original value.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electromagnetism (AREA)
  • Ceramic Engineering (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Thermistors And Varistors (AREA)
  • Conductive Materials (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Emergency Protection Circuit Devices (AREA)
EP82301765A 1981-04-02 1982-04-02 Strahlungsvernetzung der PTC-leitfähigen Polymere Expired EP0063440B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82301765T ATE46982T1 (de) 1981-04-02 1982-04-02 Strahlungsvernetzung der ptc-leitfaehigen polymere.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US25049181A 1981-04-02 1981-04-02
US250491 1981-04-02
US254352 1981-04-15
US06/254,352 US4426633A (en) 1981-04-15 1981-04-15 Devices containing PTC conductive polymer compositions

Related Child Applications (1)

Application Number Title Priority Date Filing Date
EP88117360.3 Division-Into 1982-04-02

Publications (3)

Publication Number Publication Date
EP0063440A2 true EP0063440A2 (de) 1982-10-27
EP0063440A3 EP0063440A3 (en) 1983-04-13
EP0063440B1 EP0063440B1 (de) 1989-10-04

Family

ID=26940917

Family Applications (2)

Application Number Title Priority Date Filing Date
EP88117360A Expired - Lifetime EP0311142B1 (de) 1981-04-02 1982-04-02 Vernetzung von PTC-leitfähigen Polymeren durch Strahlung
EP82301765A Expired EP0063440B1 (de) 1981-04-02 1982-04-02 Strahlungsvernetzung der PTC-leitfähigen Polymere

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP88117360A Expired - Lifetime EP0311142B1 (de) 1981-04-02 1982-04-02 Vernetzung von PTC-leitfähigen Polymeren durch Strahlung

Country Status (6)

Country Link
EP (2) EP0311142B1 (de)
JP (1) JPH053101A (de)
DE (2) DE3280447T2 (de)
GB (1) GB2096393B (de)
HK (1) HK83689A (de)
SG (1) SG89388G (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU587237B2 (en) * 1985-03-14 1989-08-10 Raychem Limited Electrical devices comprising cross-linked conductive polymers
US4907340A (en) * 1987-09-30 1990-03-13 Raychem Corporation Electrical device comprising conductive polymers
US4924074A (en) * 1987-09-30 1990-05-08 Raychem Corporation Electrical device comprising conductive polymers
EP0388990A2 (de) 1986-02-20 1990-09-26 RAYCHEM CORPORATION (a Delaware corporation) Einen ionentauschenden Stoff verwendende Verfahren und Gegenstände

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100392572B1 (ko) * 1995-03-22 2003-10-17 레이켐 코포레이션 전기소자
DE953992T1 (de) * 1995-08-15 2000-04-20 Bourns, Multifuse (Hong Kong) Ltd. Oberflächenmontierte leitfähige Polymer-Bauelemente und Verfahren zur Herstellung derselben
TW309619B (de) 1995-08-15 1997-07-01 Mourns Multifuse Hong Kong Ltd
DE19548741A1 (de) 1995-12-23 1997-06-26 Abb Research Ltd Verfahren zur Herstellung eines Materials für PTC-Widerstände
US5814264A (en) * 1996-04-12 1998-09-29 Littelfuse, Inc. Continuous manufacturing methods for positive temperature coefficient materials
TW343423B (en) * 1996-08-01 1998-10-21 Raychem Corp Method of making a laminate comprising a conductive polymer composition
US6020808A (en) 1997-09-03 2000-02-01 Bourns Multifuse (Hong Kong) Ltd. Multilayer conductive polymer positive temperature coefficent device
KR20010079908A (ko) 1998-09-25 2001-08-22 추후보정 정의 온도 계수 폴리머 재료 제조 방법
DE10310722A1 (de) 2003-03-10 2004-09-23 Tesa Ag Elektrisch erwärmbare Haftklebemasse
TW200520627A (en) * 2003-10-21 2005-06-16 Tyco Electronics Raychem Kk PTC element and starter circuit for fluorescent lamp
DE102007007617A1 (de) 2007-02-13 2008-08-14 Tesa Ag Intrinsisch erwärmbare heißschmelzklebrige Flächengebilde
DE102008034748A1 (de) 2008-07-24 2010-01-28 Tesa Se Flexibles beheiztes Flächenelement
DE102008063849A1 (de) 2008-12-19 2010-06-24 Tesa Se Beheiztes Flächenelement und Verfahren zu seiner Befestigung
DE102009010437A1 (de) 2009-02-26 2010-09-02 Tesa Se Beheiztes Flächenelement
CN102412094B (zh) * 2010-09-20 2014-12-31 胜德国际研发股份有限公司 保护电路
US10373745B2 (en) 2014-06-12 2019-08-06 LMS Consulting Group Electrically conductive PTC ink with double switching temperatures and applications thereof in flexible double-switching heaters
US11332632B2 (en) 2016-02-24 2022-05-17 Lms Consulting Group, Llc Thermal substrate with high-resistance magnification and positive temperature coefficient ink
WO2020016853A1 (en) 2018-07-20 2020-01-23 LMS Consulting Group Thermal substrate with high-resistance magnification and positive temperature coefficient
US10822513B1 (en) 2019-04-26 2020-11-03 1-Material Inc Electrically conductive PTC screen printable ink composition with low inrush current and high NTC onset temperature

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3351882A (en) * 1964-10-09 1967-11-07 Polyelectric Corp Plastic resistance elements and methods for making same
JPS5123543A (ja) * 1974-08-22 1976-02-25 Dainippon Printing Co Ltd Dodenseikobunshizairyo
FR2321751A1 (fr) * 1975-08-04 1977-03-18 Raychem Corp Perfectionnement aux compositions a coefficient de temperature positif
GB1604735A (en) * 1978-04-14 1981-12-16 Raychem Corp Ptc compositions and devices comprising them
BE859776A (fr) * 1976-10-15 1978-04-14 Raychem Corp Compositions a coefficient de temperature positif et dispositifs en comprenant
US4200973A (en) * 1978-08-10 1980-05-06 Samuel Moore And Company Method of making self-temperature regulating electrical heating cable

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU587237B2 (en) * 1985-03-14 1989-08-10 Raychem Limited Electrical devices comprising cross-linked conductive polymers
EP0388990A2 (de) 1986-02-20 1990-09-26 RAYCHEM CORPORATION (a Delaware corporation) Einen ionentauschenden Stoff verwendende Verfahren und Gegenstände
US4907340A (en) * 1987-09-30 1990-03-13 Raychem Corporation Electrical device comprising conductive polymers
US4924074A (en) * 1987-09-30 1990-05-08 Raychem Corporation Electrical device comprising conductive polymers

Also Published As

Publication number Publication date
GB2096393B (en) 1986-01-02
GB2096393A (en) 1982-10-13
EP0311142A2 (de) 1989-04-12
EP0311142A3 (en) 1989-04-26
EP0063440B1 (de) 1989-10-04
SG89388G (en) 1989-07-14
DE3280447D1 (de) 1994-01-27
EP0063440A3 (en) 1983-04-13
JPH053101A (ja) 1993-01-08
DE3279970D1 (en) 1989-11-09
DE3280447T2 (de) 1994-07-14
EP0311142B1 (de) 1993-12-15
HK83689A (en) 1989-10-27

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