Patent US3633421A successfully refreshed from Google Patents.
EP0418807A2
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Magnetic dispersions of ferrite particles with high magnetic energy product in flexible highly saturated nitrile rubber and methods of producing the same
Assignee: RJF International Corp
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Filing: 1990-09-18
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Granted: —
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Expires: 2010-09-18
Abstract
Abstract A flexible magnetic blend composition is provided which is comprised of high energy ferrite magnetic particles in a flexible high temperature resistant and oil resistant polymer binder. The binder system is preferably a highly saturated nitrile rubber (HSN) or a polymer alloy of the same in which a HSN is the major polymer containing alloying polymers and/or additives which are compatible with processing, subsequent electron beam curing, and final product performance. The system binder is highly loaded usually from 55 to 65 volume percent with the high energy ferrite particles, i.e, barium and/or strontium ferrite particles, which can produce bonded magnets with a maximum energy product of at least 1.0 megagauss-oersteds, a remenance, Br, of at least 2000 gauss, a coercive force, H c , of at least 1800 oersteds, and an intrinsic coercivity, H ci , of at least 2000 oersteds. The process for production of this system involves the binder system and ferrite particles being mixed, the ferrite particles oriented in a preferred direction during processing, then formed into a final geometry before being cured by high voltage electron beam radiation, preferably in excess of 3,000,000 electron volts. The electron beam curing in the solid state fixes dimensional stability, magnetic properties, oil, solvent, and chemical resistance of the part even when exposed to subsequent hostile temperature environments of 125 o C or higher. Any off geometry parts or trim produced in the process prior to radiation curing can be recycled through processing several times without fear of premature cure.
Inventors
- 👤 Raymond Charles Srail
- 👤 Richard August Glover
- 👤 Tiong Ho Kuan
- 👤 Thomas Raymond Szczepanski
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 22:02
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; H01F1/113; H01F1/117; C; C08; C08K; C08K3/00; C08K3/18; C08K3/20; C08K3/22; C08K3/24; C08K2201/00; C08K2201/01; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
158 words
A flexible magnetic blend composition having a maximum energy product of at least 1.0 megagauss-oersteds; a remenance, Br, of at least about 2,000 gauss; a coercive force, Hc, of at least about 1800 oersteds; an intrinsic coercivity, Hci, of at least about 2,000 oersteds; said composition comprising a mixture of magnetic particles of strontium and/or barium ferrite in a binder system; said composition after shaping and curing by exposure to a high voltage electron beam being able to retain at least about 20 percent tensile elongation at break measured at 23 o C (ASTM D412) after 100 hours of hot air aging at 125 o C, and swell less than about 5 volume percent in ASTM #1 and #3 oils after 46 hours soak at 23 o C, said mixture further being capable of being shaped or formed in an extruded strip or calendered sheet which will hold its shape before and after high voltage electron beam cure.
Claim 2
Dependent Claim
158 words
A flexible magnetic blend composition having a maximum energy product of at least 1.0 megagauss-oersteds; a remenance, Br, of at least about 2,000 gauss; a coercive force, Hc, of at least about 1800 oersteds; an intrinsic coercivity, Hci, of at least about 2,000 oersteds; said composition comprising a mixture of magnetic particles of strontium and/or barium ferrite in a binder system; said composition after shaping and curing by exposure to a high voltage electron beam being able to retain at least about 20 percent tensile elongation at break measured at 23 o C (ASTM D412) after 100 hours of hot air aging at 125 o C, and swell less than about 5 volume percent in ASTM #1 and #3 oils after 46 hours soak at 23 o C, said mixture further being capable of being shaped or formed in an extruded strip or calendered sheet which will hold its shape before and after high voltage electron beam cure.
Claim 3
Dependent Claim
29 words
A flexible magnetic blend composition as set forth in Claim 1, wherein said magnetic particles are present at about at least 55 percent by volume of the blend composition.
Claim 4
Dependent Claim
29 words
A flexible magnetic blend composition as set forth in Claim 2, wherein said binder polymer comprises at least about 70 percent by weight of a highly saturated nitrile rubber.
Claim 5
Dependent Claim
32 words
A flexible magnetic blend composition as set forth in Claim 3, wherein said highly saturated nitrile rubber has a bound acrylonitrile content of from about 30 to about 50 percent by weight.
Claim 6
Dependent Claim
32 words
A flexible magnetic blend composition as set forth in Claim 4, wherein said highly saturated nitrile rubber has a bount acrylonitrile content of from about 34 to about 48 percent by weight.
Claim 7
Dependent Claim
31 words
A flexible magnetic blend composition as set forth in Claim 5, wherein said highly saturated nitrile rubber has a nitrile content of from about 36 to about 45 percent by weight.
Claim 8
Dependent Claim
24 words
A flexible magnetic blend composition as set forth in Claim 3, wherein said highly saturated nitrile rubber is at least about 85 percent saturated.
Claim 9
Dependent Claim
24 words
A flexible magnetic blend composition as set forth in Claim 7, wherein said highly saturated nitrile rubber is at least about 90 percent saturated.
Claim 10
Dependent Claim
39 words
A flexible magnetic blend composition as set forth in Claim 2, wherein said magnetic particles comprise at least 50 percent by volume of said blend composition and have an average particle size from about 0.7 to about 2.5 microns.
Claim 11
Dependent Claim
27 words
A flexible magnetic blend composition as set forth in Claim 9, wherein said magnetic particles have an average particle size from about 0.8 to about 1.6 microns.
Claim 12
Dependent Claim
31 words
A flexible magnetic blend composition as set forth in Claim 3, wherein said binder polymer further comprises up to about 30 percent by weight of an impact modified acrylonitrile-methylacrylate thermoplastic copolymer.
Claim 13
Dependent Claim
30 words
A flexible magnetic blend composition as set forth in Claim 3, wherein said polymer further comprises up to about 30 percent by weight of a peroxide curable epichlorohydrin-ethylene oxide elastomer.
Claim 14
Dependent Claim
43 words
A process for forming a magnetic blend composition comprising: mixing a polymeric binder system and ferrite magnetic particles to form a mixture; shaping a form from said mixture; and curing said mixture in said form by exposing said mixture to an electron beam.
Claim 15
Dependent Claim
43 words
A process for forming a magnetic blend composition comprising: mixing a polymeric binder system and ferrite magnetic particles to form a mixture; shaping a form from said mixture; and curing said mixture in said form by exposing said mixture to an electron beam.
Claim 16
Dependent Claim
24 words
A process as set forth in Claim 13, wherein said ferrite magnetic particles comprise at least about 55 percent by volume of said mixture.
Claim 17
Dependent Claim
29 words
A process as set forth in Claim 14, wherein a further step of orienting the ferrite particles in the preferred magnetic orientation is included prior to said curing step.
Claim 18
Dependent Claim
28 words
A process as set forth in Claim 13, wherein the electron beam accelerator used to cure the composition has a voltage of at least about 1,000,000 electron volts.
Claim 19
Dependent Claim
24 words
A process as set forth in Claim 13, wherein said composition is cured by electron beam radiation dosage of at least about 2.5 megarads.
Claim 20
Dependent Claim
32 words
A process as set forth in Claim 15, wherein said polymeric binder system comprises at least one polymer which is at least 70 percent by weight of a highly saturated nitrile rubber.
Claim 21
Dependent Claim
36 words
A process as set forth in Claim 18, wherein said highly saturated nitrile rubber has a bound acrylonitrile content from about 30 to about 50 percent by weight and is at least about 85 percent saturated.
Claim 22
Dependent Claim
36 words
A process as set forth in Claim 19, wherein said highly saturated nitrile rubber has a bound acrylonitrile content from about 36 to about 48 percent by weight and is at least about 90 percent saturated.
Claim 23
Dependent Claim
29 words
A process as set forth in Claim 18, wherein said polymeric binder system further comprises up to about 30 percent by weight of an impact modified acrylonitrile-methylacrylate thermoplastic copolymer.
Claim 24
Dependent Claim
29 words
A process as set forth in Claim 18, wherein said polymeric binder system further comprises up to about 30 percent by weight of a peroxide curable epichlorohydrin-ethylene oxide elastomer.
References Cited (Backward Citations)
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