WO1998050460A1 - Coussinet magnetique flexible a haute resistance - Google Patents

Coussinet magnetique flexible a haute resistance Download PDF

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Publication number
WO1998050460A1
WO1998050460A1 PCT/US1997/007524 US9707524W WO9850460A1 WO 1998050460 A1 WO1998050460 A1 WO 1998050460A1 US 9707524 W US9707524 W US 9707524W WO 9850460 A1 WO9850460 A1 WO 9850460A1
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WO
WIPO (PCT)
Prior art keywords
flexible
pad
magnetic
magnetic pad
flexible magnetic
Prior art date
Application number
PCT/US1997/007524
Other languages
English (en)
Inventor
Thomas C Hampton
Original Assignee
Mrt, Inc.
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
Application filed by Mrt, Inc. filed Critical Mrt, Inc.
Priority to EP97922647A priority Critical patent/EP0981577A1/fr
Priority to PCT/US1997/007524 priority patent/WO1998050460A1/fr
Priority to AU28264/97A priority patent/AU2826497A/en
Publication of WO1998050460A1 publication Critical patent/WO1998050460A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/10—Metal compounds

Definitions

  • the present invention relates generally to flexible magnetic pads having a magnetic core comprising a particulate magnetic material embedded or dispersed in a substantially continuous phase of a flexible, most preferably elastomeric, polymeric material. More particularly, the invention preferably relates to a high strength flexible magnetic pad having a magnetic core material comprising powdered neodymium-iron-boron or neodymium-cobalt-iron in combination with at least one other powdered iron alloy component having a smaller average particle size so that the smaller particles occupy the interstices between the particles of magnetic core material.
  • the magnetic pads of the invention are believed to be especially useful for therapeutic applications and for other applications where a flexible pad having a strong magnetic field with oppositely facing, single pole surfaces is desired.
  • magnetic fields such as those created by permanent magnets can have therapeutic effects on the human body.
  • the therapeutic effects are believed to result from increased blood circulation in the area of the body subjected to the influence of the magnetic field.
  • the use of rigid, permanent magnets in such therapeutic applications has diminished due to the availability of magnetic pads that are flexible enough to conform substantially to a portion of the body surface without causing discomfort to the user.
  • Others have devoted considerable effort to creating magnetic pads having an alternating magnetic pole orientation of optimal design to supposedly induce electrical currents within the treatment area irrespective of the orientation of the blood vessels.
  • magnetic pads have been developed with alternating magnetic poles arranged in spirals, checkerboard patterns, rings, radial sectors, and the like.
  • While flexible magnetic pads having alternating magnetic pole designs are effective at inducing electrical currents within a targeted treatment area, they have several drawbacks. Magnetic field strength decreases much more rapidly per unit distance from a magnetic pad having alternating magnetic poles than from one having single pole surfaces. This effect reduces the depth of penetration of the magnetic field into the targeted treatment area, producing only surface effects. To increase penetration depth, stronger magnets need to be used or additional percentages of magnetic material must be suspended within the pad, which can make the magnetic pad heavier and less flexible.
  • Alternating magnetic pole designs are also believed to reduce the effect of the Lorentz forces on charged particles within the blood vessels. Under the influence of a directionally changing magnetic field, charged particles within the treatment area are first accelerated, then slowed, as they travel across boundaries of adjacent zones having different magnetic polarities.
  • Plastic magnet compositions containing niobium-iron-boron magnetic powder surface-treated with a polyorganosiloxane resin are disclosed in Japanese Publication No. JP3188601 , dated August 16, 1991.
  • Flexible magnetic pads for therapeutic use having alternating north and south magnetic poles on a single surface are disclosed in U.S. 4,549,532.
  • the pads disclosed therein contain permanent magnetic particles of unspecified size, such as barium ferrite or strontium ferrite, embedded in a rubbery-flexible synthetic material.
  • a reversible magnetic therapeutic device for human or animal use having a two-sided flexible wrapper and a plurality of magnets supported in pockets in the wrapper, with all the north poles on one side of the wrapper and all south poles on the opposite side, is disclosed in U.S. 4,587,956.
  • magnetic pads having a powdered particulate magnetic core surrounded by a flexible polymeric material and having significantly improved magnetic strength and penetrating capability for therapeutic use can be made by incorporating into the magnetic core from about 40 to about 60 weight percent of a first ferromagnetic material such as neodymium-iron-boron or neodymium-cobalt-iron having a particle size ranging from about 25 to about 325 microns, and primarily about 200 microns, and a lesser amount, most preferably about 15 weight percent, of at least one other iron alloy filler material having a smaller predetermined average particle size small enough that the smaller particles fill a substantial number of the interstices between the particles of the first ferromagnetic material.
  • a first ferromagnetic material such as neodymium-iron-boron or neodymium-cobalt-iron having a particle size ranging from about 25 to about 325 microns, and primarily about 200 microns, and a lesser amount, most preferably about
  • the subject magnetic pads contain from about 5 to about 15 weight percent of a ferromagnetic filler material such as strontium ferrite, barium ferrite, or strontium barium ferrite, most preferably having an average particle size of about 50 microns, plus or minus about 7 microns.
  • a ferromagnetic filler material such as strontium ferrite, barium ferrite, or strontium barium ferrite
  • the subject magnetic pads have oppositely facing, single pole surfaces.
  • the magnetic core of the subject magnetic pads is encapsulated within a layer of polymeric material having a thickness of from about 25 microns up to about 10 mils, and most preferably about 5 mils. The use of an encapsulating polymeric surface layer reduces the likelihood of discoloration or reaction due to contact between the skin (or perspiration) and the metallic components of the magnetic core.
  • the subject magnetic pads will maintain a constant field strength ranging from about 130 to about 320 gauss over hardness values (Shore A Durometer) ranging from about 10 to about 80, and will pass a 1/8 Curved Mandrel Test (Dow Corning Corporate Test Method 0895).
  • FIG. 1 is a top perspective view of a flexible magnetic pad of the invention.
  • FIG. 2 is an enlarged partial cross-sectional view taken along line 2-2 of FIG. 1.
  • magnetic pad 10 is desirably sufficiently flexible to enable it to drape over and fit any external contour of the human body, such as a knee, arm or finger, and thereby provide therapeutic relief from various pains and disorders.
  • the magnetic pad is also desirably elastic to facilitate elongation or stretching when wrapped around joints, although substantial elasticity is not necessarily required.
  • FIGS. 1 and 2 are simplified for illustrative purposes and are not drawn to scale. Although depicted in FIG. 1 in a generally circular configuration, magnetic pad 10 can be made rectangular or in another regular or irregular shape particularly well suited for a particular application such as, for example, use around an ankle or elbow.
  • magnetic pad 10 preferably comprises magnetic core 12 further comprising a plurality of ferromagnetic particles 14, 24 disposed inside a substantially continuous phase of an elastomeric polymer 16.
  • the ferromagnetic particles 14, 24 are preferably distributed substantially evenly across magnetic pad 10 between top and bottom surfaces 18, 20, respectively, as discussed below.
  • sealing layer 22 is made of the same or a different polymeric material and desirably encapsulates magnetic core 12.
  • Magnetic pad 10 is preferably magnetized so that top and bottom surfaces 18, 20, respectively, each have an oppositely facing single magnetic pole.
  • a preferred polymer 16 for use as the substantially continuous elastomeric phase of magnetic core 12 and for sealing layer 22 is silicone rubber, which is compatible with human skin (i.e., hypoallergenic) and conformable to the body surface, if desired, the polymeric materials used within magnetic core 12 and as sealing layer 22 may be different in kind, or may be similar polymers with different durometers to improve pad comfort or flexibility. Silicone rubber provides magnetic pad 10 with desired chemical and temporal stability, and also contributes to the elasticity of magnetic pad 10. Silicone rubbers usable as polymer 16 include polysiloxane vinyl end- blocked polymers and polysiloxane hydroxy end-blocked polymers of differing viscosities, i.e., low or high consistency silicone.
  • Low consistency silicone is a flowable material before curing and can be poured into molds or rolled into sheeting.
  • High consistency silicone is a non-flowable solid that is mixed with metal powder and catalyzed on a two roll mixer and then forced into molds under very high pressure in transfer presses.
  • the silicone itself serves as the carrier of the ferromagnetic powder, and is not used just as a binder to hold the metallic particles to the carrier.
  • magnetic pad 10 will comprise from about 35 up to about 40 weight percent of silicone polymer, although a lesser or greater amount of polymeric material can also be used satisfactorily depending upon factors such as the particular polymer(s), the type and loading of the ferrogmagnetic powders, the desired flexibility, the thickness of the sealing layer, and the intended use.
  • Silicones useful in making the magnetic pads of the invention are commercially available, for example, from Dow Corning, GE, Wacker Silicones Inc., and others.
  • the ferromagnetic particles embedded in magnetic core 12 will preferably have a high magnetic retentivity with a residual induction of over 0.8 T (making ferrites proprietary) to produce the desired magnetic field necessary to provide therapeutic relief in a flexible magnetic pad 10.
  • Particles 14 preferably comprise from about 40 to about 60 weight percent of magnetic pad 10, with a particle size ranging from about 25 to about 325 microns, a size large enough to act as permanent magnets yet small enough to fit within magnetic core 12 and afford the necessary flexibility.
  • particles 14 are Neodymium-lron-Boron (Nd 2 Fe 14 B) particles having an average particle size of about 200 microns.
  • Magnetic core 12 preferably further comprises from about 5 to about 15 percent by weight of magnetic pad 10 of particles 24 of a ferromagnetic filler material having an average particle size smaller that the average particle size of particles 14, most preferably about 50 microns, to fill the interstices between particles 14 within magnetic core 12.
  • Strontium ferrite having a density of about 4.9 g/cm 3 , is a preferred particulate filler material.
  • One commercially available source of powdered strontium ferrite is The Hoosier Magnetics Group.
  • powdered iron alloy materials useful as the ferromagnetic filler material include, for example, barium ferrite and strontium barium ferrite.
  • Magnetic core 12 comprising particles 14, 24 dispersed throughout a matrix of polymeric material such as silicone polymer, is preferably from about 1.25 to about 6.25 mm thick, and most preferably from about 1.5 to about 2 mm thick.
  • Sealing layer 22 again preferably a silicone polymer as previously described, surrounds magnetic core 12 to prevent particles 14, 24 at the surface of magnetic core 12 from flaking off the surface and to prevent the metallic particles from contacting the skin of a user.
  • the thickness of sealing layer 22 can range from about 25 microns up to about 10 mils or more, and a sealing layer having a thickness of about 5 mils is particularly preferred.
  • magnetic core 12 of magnetic pad 10 is formed by airless mixing 40-60% by weight of the Neodymium-lron-Boron particles 14 and 5-15% by weight of the strontium ferrite particles 24 in a one or two part silicone rubber material 16, including minor effective amounts, generally less than one weight percent, of any suitable, conventional, well known catalyst and cross-linking agent.
  • a minor amount, such as about one weight percent, of a pigment such as titanium dioxide pigment can also be added if desired.
  • the resulting mass is then formed into sheets, preferably 1.5 to 2 mm thick as described above, either through calendering or a continuous casting process, or is poured into appropriately dimensioned molds.
  • Backing sheets such as Mylar® sheeting material, may be utilized as is known in the art to provide a nonadherent surface for maintaining the desired thickness of magnetic core 12 throughout the curing process.
  • the core layer 14 is either platinum or peroxide cured, with the continuous casting platinum 120- I50°C dry heat cure being preferred over the steam peroxide cures used with calendering and molding.
  • the magnetic core 12 is preferably cut into shapes and sizes desired for the intended application. Typically, magnetic core 12 will be cut into either circular or rectangular patterns of differing dimensions dependent upon the area of desired treatment, but it is understood that the magnetic pad 10 can be cut to any size or shape for custom applications.
  • magnetic core 12 is preferably surrounded by and encapsulated within sealing layer 22 by coating magnetic core 12 with additional silicone rubber material.
  • Magnetic pad 10 is subsequently introduced into the air-gap of an electromagnet capable of producing a magnetic flux density in excess of 2.5 T to impart a magnetic remanent field to particles 14, 24.
  • particles 14 are Neodymium-lron-Boron, the resulting magnetic field measured at 6.35 mm from the magnetic pad 10 will exceed 2 mT, it being understood that increased percentages of particles 14 will result in higher remanent fields, as will the inclusion of particles 24 as described above.
  • Magnetic pad 10 is desirably magnetized in a known manner to cause top surface 18 of the pad to be one magnetic pole and bottom surface 20 of the pad to be the opposite magnetic pole, thereby avoiding the alternating magnetic poles so prevalent in the prior art.
  • magnetic pads were prepared as described above using eight different compositions, all comprising Magnequench MQP-B powder as the magnetic core.
  • Two compositions contained 60% and 80% by weight, respectively, magnetic core material with no ferromagnetic filler material.
  • the other six compositions contained 50 weight percent Magnequench MQP-B powder as the magnetic core and 30 weight percent of a powdered iron alloy as shown in the table below. All pads passed the flexibility test as stated above.
  • the pads were magnetized and six samples o were prepared for each composition. The magnetic field strengths were then measured for each of the six samples of each composition, and the results are reported in Table 1 below.
  • Hoosier 402 b. Hoosier 406 c. Hoosier 410 d. Hoosier 170 e. Hoosier 181 f. Hoosier 130
  • magnetic pad 10 is placed on a portion of the body needing treatment and secured in place by elastic bands, bandages, band-aids or in other known ways (not shown), with the north pole side (labeled as such on a manufactured pad) of the magnetic pad 10 preferably being placed closest to the body.
  • An adhesive strip can also be attached to the magnetic pad 10 to facilitate securing the pad to the treatment area. Due to the flexibility of the magnetic pad 10, the pad will conform to the treatment area regardless of the size or angular orientation of the body part.
  • the magnetic field generated by the magnetic pad 10 penetrates into the body and is believed to impart a Lorentz force on the numerous charged particles flowing within the blood vessels causing increased blood flow through the treatment area.
  • the magnetic pad 10 increases the therapeutic ability of magnetic field's by providing a form-fitting device having single magnetic poles on each surface. For example, providing a single pole magnetic device increases the penetration of the magnetic field into the treatment area as compared to alternating magnetic pole pads of equal magnetic strength as measured at their respective surfaces. Moreover, the single pole field maximizes the Lorentz forces experienced within the treatment area. Under a directionally changing magnetic field, the Lorentz forces would alternate as well, thereby causing the charged particles within the body to be pushed in one direction and then be suddenly slowed and pushed in the opposite direction as the particles move through the field. The flexibility of the magnetic pad 10 provides additional physiological advantages.
  • the magnetic pad 10 By being form-fitting, the magnetic pad 10 provides magnetic field penetration over a greater percentage of the treatment area as it can be conformed around elbows and other curved body parts. Thus in treating a sore shoulder, the magnetic pad 10 will lie smoothly against the front, top and back of the shoulder, as well as along the neck and upper arm, thereby penetrating the entire area.
  • the magnetic pad 10 can also be used for even the smallest human extremities and cylindrical body parts such as fingers and ankles.
  • joints do not have to be immobilized during treatment as the magnetic pad 10 is desirably elastic, facilitating its use during exercise or other movement.
  • specially configured magnetic pads are not necessary for each differently shaped treatment area as the flexibility of the magnetic pad 10 allows it to form-fit to all contours of the human body.
  • the subject invention is also believed to have industrial applicability.
  • the ferromagnetic particles 14 need not be Neodymium-lron-Boron particles, so long as they provide a residual induction of over 0.8 T.
  • the percentage of particles 14, 24 required in magnetic core 12 can be reduced with increased residual induction. By decreasing such percentage, the flexibility of the magnetic pad 10 can be further increased.
  • the magnetic pad 10 can be cut into specially designed shapes, such as to fit within a shoe.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Magnetic Treatment Devices (AREA)

Abstract

L'invention concerne des coussinets magnétiques (10) flexibles présentant un noyau magnétique (12) dispersé dans une couche externe (22) polymère flexible dont les surfaces (18, 20) unipolaires se font face et ont une résistance magnétique et une profondeur de pénétration améliorées. Le noyau magnétique (12) contient entre environ 40 et 60 % en poids d'un matériau ferromagnétique (14) tel que Nd-Fe-B présentant une granulométrie moyenne prédéterminée comprise entre environ 25 et 325 microns, et au moins un autre matériau (14) de remplissage ferromagnétique présentant une granulométrie moyenne prédéterminée plus petite, de manière que les plus petites particules remplissent un nombre sensible d'interstices entre les particules du premier matériau ferromagnétique. Selon un mode de réalisation préféré, le matériau de remplissage ferromagnétique contient entre environ 5 et 15 % en poids de ferrite de strontium dont la granulométrie moyenne est d'environ 50 microns.
PCT/US1997/007524 1997-05-02 1997-05-02 Coussinet magnetique flexible a haute resistance WO1998050460A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP97922647A EP0981577A1 (fr) 1997-05-02 1997-05-02 Coussinet magnetique flexible a haute resistance
PCT/US1997/007524 WO1998050460A1 (fr) 1997-05-02 1997-05-02 Coussinet magnetique flexible a haute resistance
AU28264/97A AU2826497A (en) 1997-05-02 1997-05-02 High strength flexible magnetic pad

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1997/007524 WO1998050460A1 (fr) 1997-05-02 1997-05-02 Coussinet magnetique flexible a haute resistance

Publications (1)

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WO1998050460A1 true WO1998050460A1 (fr) 1998-11-12

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EP (1) EP0981577A1 (fr)
AU (1) AU2826497A (fr)
WO (1) WO1998050460A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1164600A2 (fr) * 2000-06-09 2001-12-19 Anchor Magnets Limited Bande magnétique flexible
US6652767B2 (en) * 2001-04-09 2003-11-25 Enplas Corporation Composition for plastic magnet
WO2004039876A2 (fr) * 2002-10-29 2004-05-13 Dupont Dow Elastomers L.L.C. Pieces en elastomere resistant au plasma
CN115472370A (zh) * 2022-09-20 2022-12-13 北京大学 一种柔性永磁材料、制备方法及其在磁性生物效应产品中的应用

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4443350A (en) * 1978-08-11 1984-04-17 Rockwell International Corporation Method for nondestructive magnetic inspection and rubber-like magnetic recording medium employed therein
WO1995016473A1 (fr) * 1993-12-15 1995-06-22 Mti, Inc. Bandage magnetique flexible
US5567757A (en) * 1995-07-18 1996-10-22 Rjf International Corporation Low specific gravity binder for magnets

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4443350A (en) * 1978-08-11 1984-04-17 Rockwell International Corporation Method for nondestructive magnetic inspection and rubber-like magnetic recording medium employed therein
WO1995016473A1 (fr) * 1993-12-15 1995-06-22 Mti, Inc. Bandage magnetique flexible
US5567757A (en) * 1995-07-18 1996-10-22 Rjf International Corporation Low specific gravity binder for magnets

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1164600A2 (fr) * 2000-06-09 2001-12-19 Anchor Magnets Limited Bande magnétique flexible
EP1164600A3 (fr) * 2000-06-09 2002-06-12 Anchor Magnets Limited Bande magnétique flexible
US6652767B2 (en) * 2001-04-09 2003-11-25 Enplas Corporation Composition for plastic magnet
WO2004039876A2 (fr) * 2002-10-29 2004-05-13 Dupont Dow Elastomers L.L.C. Pieces en elastomere resistant au plasma
WO2004039876A3 (fr) * 2002-10-29 2004-08-19 Dupont Dow Elastomers Llc Pieces en elastomere resistant au plasma
US6946511B2 (en) 2002-10-29 2005-09-20 Dupont Dow Elastomers, Llc Plasma resistant elastomer parts
CN115472370A (zh) * 2022-09-20 2022-12-13 北京大学 一种柔性永磁材料、制备方法及其在磁性生物效应产品中的应用
US12087482B2 (en) 2022-09-20 2024-09-10 Peking University Flexible permanent magnetic material, preparation method and application thereof in magnetic biological effect products

Also Published As

Publication number Publication date
EP0981577A1 (fr) 2000-03-01
AU2826497A (en) 1998-11-27

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