EP0080160B1 - Dauermagnete - Google Patents

Dauermagnete Download PDF

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Publication number
EP0080160B1
EP0080160B1 EP19820110609 EP82110609A EP0080160B1 EP 0080160 B1 EP0080160 B1 EP 0080160B1 EP 19820110609 EP19820110609 EP 19820110609 EP 82110609 A EP82110609 A EP 82110609A EP 0080160 B1 EP0080160 B1 EP 0080160B1
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EP
European Patent Office
Prior art keywords
composition
weight
reactive
ferrite
functional groups
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
Application number
EP19820110609
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English (en)
French (fr)
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EP0080160A1 (de
Inventor
Jerome John Blayner
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.)
Goodrich Corp
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BF Goodrich Corp
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Publication date
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/10—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • H01F1/11—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
    • H01F1/113—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles in a bonding agent
    • H01F1/117—Flexible bodies

Definitions

  • Flexible permanent magnets have been used extensively in gasket assemblies for sealing the space between the door and cabinet of refrigerators, food freezers and like structures. Such magnets also have found extensive use in a variety of other applications, including use in advertising sheet materials that can be removably attached to an appropriate metal surface, as an attaching component in storm window framing, in motors, in sheet backing for carpeting to anchor the carpeting to steel flooring, as toy components, etc.
  • such magnets may be made by incorporating a magnetic powder into an elastomer binder and shaping the composition into the desired configuration, followed by orientation of the particles of magnetic powder within the binder in order to enhance the potential magnetic properties of the composition.
  • the resulting composition is subjected to a magnetizing field to magnetize the particles of magnetic powder within the composition.
  • US-A-4,022,701 discloses the production of an anisotropic plastics magnet composed of a mixture of one or more ferromagnetic powders having a large magnetic anisotropy constant and a synthetic resin which is characterized in that one or more of a metal crosslinked resin from a copolymer of a-olefin and ⁇ , ⁇ unsaturated mono- or dicarboxylic acid or a saponified resin of a copolymer of ethylene and vinyl acetate is used as the synthetic resin and the molding is done while the magnetic field is applied under a heated condition.
  • DE-A-1 464 613 discloses a flexible permanent magnet composition containing at least 67 Vol.-% barium ferrite with a particle size smaller than 10 pm and an elastomeric binder characterized in that at least one component of the binder is selected from the group consisting of chlorosulfonated polyethylene with a high molecular weight, polyisobutylene and chlorinated polyethylene. If a high amount of the ferrite powder is used in the mix per 100 parts by weight of binder the mixes are difficult to process.
  • the mixing operation can be carried out in any convenient manner, such as by mixing the components of the magnetic composition together in a Banbury mixer, on a roll mill or in an extruder.
  • the method or methods which can be used for shaping the composition will depend to a significant degree on the configuration into which the composition is to be formed. For example, if thin sheets of the magnetic composition are desired, the sheets can be formed by a conventional calendering operation. Strip magnets of the type used in refrigerator gasket assemblies normally are formed as a continuous strip by extruding the magnetic composition through an appropriate-shaped extrusion die. Magnetization of the particles of magnetic material within the composition can be accomplished by subjecting the shaped product to a magnetic field of sufficient strength.
  • the amount of powdered magnetic material present in the magnetic composition will influence the strength of a magnet that can be formed from the composition.
  • the larger the quantity of powered magnetic material. in the composition the greater will be the strength of a magnet which can be formed from the composition (provided that the degree of orientation of the magnetic particles is equal).
  • the stiffness of the composition also increases and ultimately the composition may become friable and unable to be "worked” further.
  • the energy required for mixing or the pressure required for extrusion may become objectionably high as greater quantities of the magnetic powder are added to the composition.
  • a flexible permanent magnet composition comprising finely-divided particles of a ferrite having the formula MO . nFe 2 0 3 in which M is barium, lead or strontium and n is an integer, in an elastomeric binder, in an amount up to 1200 parts by weight or 100 parts by weight of said elastomer characterized in that the elastomeric is a polyarylic elastomer having a Mooney viscosity between 20 and 70 when measured in accordance with the procedure of ASTM Designation 1646 with a 4 minute running time at 100°C using the large rotor and with a 1 minute warm-up period, said polyacrylic elastomer being a polymer comprised of from 95 to 100 percent by weight of a backbone component having the structure derived from an alkyl acrylate, where x is an integer and n is from 2 to 8, or having the structure derived from an alkyoxy acrylate, where x in an integer, n is 2
  • the present invention provides a magnetic composition that exhibits outstanding processing characteristics that enable the composition to be processed easily using less energy input and to be extruded at extrusion pressures lower than required with current commercial compositions containing comparable loadings of magnetic material.
  • the composition is able to accommodate higher loadings of the powdered magnetic material without losing its capability of being "worked” and shaped and, as a result of the possible higher loadings, can be formed into magnets of higher strengths.
  • Magnets formed from the composition can be made into magnets that have a greater degree of flexibility than previously realized and will withstand higher temperatures without exhibiting objectionable degradation.
  • the magnetic material can be combined with the polyacrylic elastomer component of the composition in any convenient manner, such as by mixing the components of the composition together in a Banbury mixer or on a roll mill.
  • the mixed composition usually is cubed or granulated to put it in a form that can be handled easily for further processing.
  • the composition then is shaped into the desired configuration. If a flat thin sheet is desired, shaping can be accomplished on a calendering mill. If a magnet in the form of a strip is required, the cubed or granulated magnetic composition can be fed into a screw-type extruder and forced through an appropriately-shaped extrusion die to form a continuous strip of the magnetic composition of the desired cross-sectional configuration.
  • the composition also can be shaped by injection molding or by shaping in conventional sectional molds. The shaped composition thereafter is exposed to a magnetizing field to magnetize the magnetic particles with the composition.
  • reactive functional groups are reactive halogen groups having the structure where X is chlorine or bromine (such as results from the copolymerization of the alkyl acrylate or alkoxy acrylate with 2-chlorethyl vinyl ether), or reactive epoxy groups having the structure (such as results from the copolymerization of the alkyl acrylate or alkoxy acrylate with an alkyl glycidyl ether), or reactive carboxyl groups having the structure (such as results from the copolymerization of the alkyl acrylate or alkoxy acrylate with acrylic acid or methacrylic acid) or reactive hydroxyl groups having the structure (such as results from the copolymerization of the alkyl acrylate or alkoxy acrylate with an hydroxalkyl acrylate).
  • the magnetic component is a ferrite of barium, lead, or strontium, or a mixture thereof in a finely-divided state so that the individual particles desirably approach the size of the magnetic domains of the material.
  • a ferrite is defined as a material having the formula MO . nFe 2 0 3 wherein M is barium, lead or strontium and n is an integer.
  • M is barium, lead or strontium and n is an integer.
  • barium ferrite BaFe, 2 0, 9
  • the particle size of the magnetic component desirably is within the size range of 0.5 to 10 pm with an average particle size preferably being 1 to 1.5 pm.
  • composition of the present invention can accommodate up to about 1200 parts by weight of the magnetic material per 100 parts by weight of the polyacrylic binder component.
  • magnets of greater magnetic strength can be formed.
  • a processing aid for the polyacrylic binder component can be added to the composition.
  • the processing aid should have a softening point below the temperature at which the magnetic composition is mixed and shaped to produce optimum results.
  • Polyethylene homopolymers and copolymers of ethylene with an acrylic acid or vinyl acetate which have softening points when measured in accordance with the procedure described in ASTM Designation No. E-28 of between 60 to 120°C. are preferred processing aids. Desirably, from 1 to 15 parts by weight of such processing aid is used per 100 parts by weight of the polyacrylic elastomer in the magnetic composition.
  • control strip magnet had the following physical properties:
  • the polymer binders used in the examples were:
  • compositions were mixed on an open mill.
  • Mixing time for the polyacrylic elastomer binder compositions was ten (10) minutes and mixing time for the chlorosulfonated polyethylene/polyisobutylene binder compositions was 20 minutes.
  • Each composition was run through a capillary extrusion die in a constant load rheometer at the following conditions:

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Claims (9)

1. Flexible Permanentmagnet-Zusammensetzung, enthaltend feine Teilchen eines Ferrits der Formel MO. nFe203, in der M Barium, Blei oder Strontium ist und n eine ganze Zahl ist, in einem elastomeren Bindemittel in einer Menge von bis zu 1200 Gew.-Teilen auf 100 Gew.-Teile des Elastomers, dadurch gekennzeichnet, daß das Elastomer ein Polyacryl-Elastomer mit einer Mooney-Viskosität zwischen 20 und 70, gemessen nach der Arbeitsweise der ASTM-Vorschrift 1646 mit einer Laufzeit von 4 min bei 100°C unter Verwendung des großen Rotors und mit einer Aufwärmperiode von 1 min, wobei das Polyacryl-Elastomer ein Polymer ist, das zusammengesetzt ist aus 95 bis 100 Gew.-% einer Skelett-Komponente mit der von einem Alkylacrylat abgeleiteten Struktur
Figure imgb0021
in der x eine ganze Zahl ist und n 2 bis 8 ist, oder mit der von einem Alkyloxyacrylat abgeleiteten Struktur
Figure imgb0022
in der x eine ganze Zahl ist, n 2 ist und m 1 oder 2 ist, und bis zu 5 Gew.-% einer copolymerisierbaren Komponente mit reaktionsfähigen funktionellen Gruppen.
2. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß die reaktionsfähigen funktionellen Gruppen reaktionsfähige Halogen-Gruppen mit der Struktur
Figure imgb0023
sind, in der X Chlor oder Brom ist.
3. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß die reaktionsfähigen funktionellen Gruppen reaktionsfähige Epoxy-Gruppen mit der Struktur
Figure imgb0024
 5 sind.
4. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß die reaktionsfähigen funktionellen Gruppen reaktionsfähige Carboxyl-Gruppen mit der Struktur
Figure imgb0025
sind.
5. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß die reaktionsfähigen funktionellen Gruppen reaktionsfähige Hydroxyl-Gruppen mit der Struktur
Figure imgb0026
sind.
6. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß das Polyacryl-Elastomer eine Mooney-Viskosität zwischen 25 und 60, gemessen nach der Arbeitsweise der ASTM-Vorschrift 1646 mit einer Laufzeit von 4 min bei 100°C unter Verwendung des großen Rotors und mit einer Aufwärmperiode von 1 min besitzt.
7. Zusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß die feinen Teilchen des Ferrits eine Teilchengröße innerhalb des Bereichs von 0,5 bis 10 um und eine mittlere Teilchengröße von 1 bis 1,5 pm besitzen.
8. Zusammensetzung nach Anspruch 1, 2, 3, 4, 5, 6 oder 7, dadurch gekennzeichnet, daß der Ferrit Bariumferrit (BaFe12O19) ist.
9. Zusammensetzung nach Anspruch 1, 2, 3, 4, 5 oder 6, dadurch gekennzeichnet, daß die Zusammensetzung 1 bis 15 Gew.-Teile eines Polyethylen-Homopolymers oder eines Copolymers aus Ethylen mit einer Acrylsäure oder Vinylacetat auf 100 Gew.-Teile des Polyacryl-Elastomers enthält.
EP19820110609 1981-11-20 1982-11-18 Dauermagnete Expired EP0080160B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US32320981A 1981-11-20 1981-11-20
US323209 1981-11-20

Publications (2)

Publication Number Publication Date
EP0080160A1 EP0080160A1 (de) 1983-06-01
EP0080160B1 true EP0080160B1 (de) 1986-01-22

Family

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Family Applications (1)

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EP19820110609 Expired EP0080160B1 (de) 1981-11-20 1982-11-18 Dauermagnete

Country Status (3)

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EP (1) EP0080160B1 (de)
JP (1) JPS5896702A (de)
DE (1) DE3268714D1 (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2134128A (en) * 1983-01-27 1984-08-08 Oilfield Inspection Services Magnetically conductive materials and articles and methods using them
JPS6028142A (ja) * 1983-07-27 1985-02-13 Hitachi Ltd 磁気コンバ−ゼンス装置を備えたインライン形カラ−受像管および磁気コンバ−ゼンス装置の製造装置
GB8402360D0 (en) * 1984-01-30 1984-02-29 Picker Int Ltd Nmr shims
US5115063A (en) * 1989-01-30 1992-05-19 Gencorp Inc. High magnetic strength magnets containing a flexible acrylate-2-acrylamido-2-methylpropane sulfonic acid salt binder
US4911855A (en) * 1989-01-30 1990-03-27 Gencorp Inc. High magnetic strength magnets containing a flexible acrylate-amps binder
MX9101416A (es) * 1990-10-16 1994-05-31 Kimberly Clark Co Composiciones de tela polimericas amigables al ambiente.
US5990218A (en) * 1998-11-20 1999-11-23 The Goodyear Tire & Rubber Company Polymeric magnet compound

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2959832A (en) * 1957-10-31 1960-11-15 Baermann Max Flexible or resilient permanent magnets
US2999275A (en) * 1958-07-15 1961-09-12 Leyman Corp Mechanical orientation of magnetically anisotropic particles
DE1172384B (de) * 1960-03-03 1964-06-18 Magnetfab Bonn Gmbh Magnetischer flexibler Schichtkoerper
US3070841A (en) * 1960-12-07 1963-01-01 Goodrich Co B F Method and apparatus for making magnetically anisotropic elongated magnets
GB949006A (en) * 1961-05-29 1964-02-05 Goodrich Co B F Flexible permanent magnets
US3602986A (en) * 1969-10-31 1971-09-07 Du Pont Method of fabricating radially oriented magnets
US3764539A (en) * 1970-10-14 1973-10-09 Community Building Ass Of Wash Flexible ferrite permanent magnet and methods for its manufacture
IT949593B (it) * 1972-01-13 1973-06-11 Ios Ind Srl Procedimento per conferire alle strutture plastomagnetiche una matrice ottimale di materiale deformabile elastico e struttu re plastomagnetiche ottenute con tale procediment
JPS5437679B2 (de) * 1974-04-26 1979-11-16

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EP0080160A1 (de) 1983-06-01
DE3268714D1 (en) 1986-03-06

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