Polymeric resin bonded magnets

• US 20040045635A1
• Filed: 09/09/2002
• Published: 03/11/2004
• Est. Priority Date: 09/09/2002
• Status: Active Grant

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Chakrabarti, Amit, Tandon, Kunj, Bandyopadhyay, Krisanu
• Granted Patent: US 6,872,325 B2
• Time in Patent Office: Days
• US Class Current: 148/104
• CPC Class Codes: B29C 39/003 characterised by the choice of material
• CPC Class Codes: B29C 45/0001 characterised by the choice of material
• CPC Class Codes: B29K 2503/06 Metal powders, metal carbides or the like
• CPC Class Codes: B29K 2995/0008 Magnetic or paramagnetic
• CPC Class Codes: B29K 2995/0094 Geometrical properties
• CPC Class Codes: H01F 1/0558 bonded together
• CPC Class Codes: H01F 1/0578 bonded together
• CPC Class Codes: H01F 1/083 in a bonding agent
• CPC Class Codes: H01F 1/113 in a bonding agent
• CPC Class Codes: H01F 1/14758 by macromolecular organic substances
• CPC Class Codes: H01F 1/15333 containing nanocrystallites, e.g. obtained by annealing
• CPC Class Codes: H01F 1/15375 using polymers
• CPC Class Codes: H01F 1/26 by macromolecular organic substances
• CPC Class Codes: H01F 1/37 in a bonding agent
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 41/0266 Moulding; Pressing H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11

Abstract

Briefly, in accordance with one embodiment of the present invention, a process for making a magnetic composite which comprises providing a polymeric resin and a magnetic powder, the magnetic powder having a mean particle size with a value for standard deviation that is less than the value for the mean particle size of the said magnetic powder, the said magnetic composite being made by mixing said magnetic powder with said polymeric resin and molding the said mixture into a desired shape and a size and said magnetic composite having a magnetic permeability between 30 and 50. In another embodiment the present invention is a composition for a magnetic composite comprising a polymeric resin and a magnetic powder, the said powder having a mean particle size with a value of standard deviation that is less than the value of the mean particle size of the magnetic powder, wherein said magnetic composite has a magnetic permeability between about 30 and about 50.

Claims

1. A method for making a magnetic composite comprising the steps of:

i) providing a polymeric resin;

ii) providing a magnetic powder having a mean particle size with a value for standard deviation less than the value for the mean particle size of the magnetic powder;

iii) mixing said polymeric resin and said magnetic powder into a mixture; and

iv) molding said mixture into a desired shape and a size;

wherein said magnetic composite has a magnetic permeability between about 30 and about 50.

2. The method of claim 1 wherein the magnetic powder is at least one powder selected from the group consisting of ferrite powder, iron powder, nanocrystalline iron powder, cobalt-compound powder, rare earth cobalt powder, alnico powder, amorphous Fe—

B—

Si—

C powder, amorphous Fe—

Si—

B magnetic powder, Nd—

Fe—

B powder, powders of alloys of iron and nickel containing more than 30 wt. % nickel, and mixtures thereof.

3. The method of claim 1 wherein the magnetic powder is a ferrite of the form MO—

Fe₂O₃, wherein MO is a divalent oxide of a metal selected from the group consisting of Mn, Mg, Zn, Ni, Cr, Cu, Co and mixtures thereof.

4. The method of claim 1 wherein the polymeric resin is chosen from the group consisting of polyolefins, polyethylene, polypropylene, ethylene-vinylacetate copolymers, ionomers;

polyamides, nylon 6, nylon 66, nylon 12, nylon 6/66;

poly(arylene sulfides), poly(phenylene sulfide), poly(phenylene sulfide-ketone);

polyesters, polyethylene terephthalate, polybutylene terephthalate, poly(cyclohexanedimethanol terephthalate), poly(trimethylene terephthalate), poly(cyclohexanedimethanol terephthalate-co-ethylene terephthalate), polyarylates;

polyimides, polyetherimides, polyamideimides;

styrene resins, polystyrene, ABS, acrylonitrile-styrene copolymers;

chlorine-containing vinyl resins, polyvinylchloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymers, chlorinated polyethylene;

polyacrylates, polymethacrylates, polymethyl acrylate, polymethylmethacrylate;

acrylonitrile resins, polyacrylonitrile, polymethacrylonitrile;

liquid crystalline polymers, thermoplastic fluorocarbon resins, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene/hexafluoropropylene copolymers, polyvinylidene fluoride;

silicone resins, polysiloxanes, polydimethylsiloxane;

polyphenylene ether, alloys of polyphenylene ethers, polyketones, polyetheretherketone, polyetherketone, polysulfones, polyethersulfones;

polyacetals, polycarbonates, polyvinyls, polyvinyl acetate, polyvinylformal, polyvinylbutyral, polybutylene, polyisobutylene, polymethylpentene, butadiene resins, polybutadiene, polyethylene oxide;

polypropylene oxide;

elastomers, thermoplastic elastomers, ethylene-propylene rubber, polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber;

styrene-butadiene-styrene block copolymers; and

mixtures of two or more of any of these resins.

5. The method of claim 1 wherein the polymeric resin is chosen from nylon-6, liquid crystalline polymers, polycarbonates, polyolefins, polyethylene, polypropylene, poly(arylene sulfides), polyphenylene sulfide, polyphenylene ethers, alloys of polyphenylene ether, polystyrenes, polyetherketones, and mixtures of two or more of any of these resins.

6. The method of claim 1 wherein the magnetic powder comprises between about 50% and about 99% of the composite weight.

7. The method of claim 1 wherein the magnetic powder comprises between about 70% and about 95% of the composite weight.

8. The method of claim 1 wherein the magnetic powder is sieved to produce a mean particle size that has a value for standard deviation less than the value for the mean size of the powder used.

9. The method of claim 1 wherein the magnetic powder has a mean particle size from about 5 microns to about 150 microns.

10. The method of claim 1 wherein the magnetic powder has a mean particle size from about 25 microns to about 100 microns.

11. The method of claim 1 wherein the magnetic powder has a mean particle size from about 35 microns to about 55 microns.

12. The method of claim 1 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 150 microns.

13. The method of claim 1 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 75 microns.

14. The method of claim 1 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 50 microns.

15. The method of claim 1 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 20 microns.

16. The method of claim 1 wherein the magnetic composite contains mold release agents selected from the group consisting of stearyl stearate, beeswax, montan wax, paraffin wax and combinations thereof.

17. The method as claimed in claim 1 wherein said particles of magnetic powder of the said mixture of step (iii) are subjected to an applied magnetic field during the molding of step (iv).

18. A composition for a magnetic composite comprising a polymeric resin and a magnetic powder, the said powder having a mean particle size with a value of standard deviation that is less than the value of the mean particle size of the magnetic powder, wherein said magnetic composite has a magnetic permeability between about 30 and about 50.

19. The composition for a magnetic composite of claim 18 wherein the magnetic powder is at least one magnetic powder selected from the group consisting of ferrite powder, iron powder, nanocrystalline iron powder, cobalt-compound powder, rare earth cobalt powder, alnico powder, amorphous Fe—

B—

Si—

C powder, amorphous Fe—

Si—

B magnetic powder, Nd—

Fe—

B powder, powders of alloys of iron and nickel containing more than 30 wt. % nickel, and mixtures thereof.

20. The composition for a magnetic composite of claim 18 wherein the magnetic powder is a ferrite of the form MO—

Fe₂O₃, wherein MO is a divalent oxide of a metal selected from the group consisting of Mn, Mg, Zn, Ni, Cr, Cu, Co and mixtures thereof.

21. The composition for a magnetic composite of claim 18 wherein the polymeric resin is chosen from the group consisting of polyolefins, polyethylene, polypropylene, ethylene-vinylacetate copolymers, ionomers;

polyamides, nylon 6, nylon 66, nylon 12, nylon 6/66;

poly(arylene sulfides), poly(phenylene sulfide), poly(phenylene sulfide-ketone);

polyesters, polyethylene terephthalate, polybutylene terephthalate, poly(cyclohexanedimethanol terephthalate), poly(trimethylene terephthalate), poly(cyclohexanedimethanol terephthalate-co-ethylene terephthalate), polyarylates;

polyimides, polyetherimides, polyamideimides;

styrene resins, polystyrene, ABS, acrylonitrile-styrene copolymers;

chlorine-containing vinyl resins, polyvinylchloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymers, chlorinated polyethylene;

polyacrylates, polymethacrylates, polymethyl acrylate, polymethylmethacrylate;

acrylonitrile resins, polyacrylonitrile, polymethacrylonitrile;

liquid crystalline polymers, thermoplastic fluorocarbon resins, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene/hexafluoropropylene copolymers, polyvinylidene fluoride;

silicone resins, polysiloxanes, polydimethylsiloxane;

polyphenylene ether, alloys of polyphenylene ethers, polyketones, polyetheretherketone, polyetherketone, polysulfones, polyethersulfones;

polyacetals, polycarbonates, polyvinyls, polyvinyl acetate, polyvinylformal, polyvinylbutyral, polybutylene, polyisobutylene, polymethylpentene, butadiene resins, polybutadiene, polyethylene oxide;

polypropylene oxide;

elastomers, thermoplastic elastomers, ethylene-propylene rubber, polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber;

styrene-butadiene-styrene block copolymers; and

mixtures of two or more of any of these resins.

22. The composition for a magnetic composite of claim 21 wherein the polymeric resin is chosen from nylon-6, liquid crystalline polymers, polycarbonates, polyolefins, polyethylene, polypropylene, poly(arylene sulfides), polyphenylene sulfide, polyphenylene ethers, alloys of polyphenylene ether, polystyrenes, polyetherketones, and mixtures of two or more of any of these resins.

23. The composition for a magnetic composite of claim 18 wherein the magnetic powder comprises between about 50% and about 99% of the composite weight.

24. The composition for a magnetic composite of claim 18 wherein the magnetic powder comprises between about 70% and about 95% of the composite weight.

25. The composition for a magnetic composite of claim 18 wherein the magnetic powder is sieved to produce a mean particle size that has a value for standard deviation less than the value for the mean size of the powder used.

26. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size from about 5 microns to about 150 microns.

27. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size from about 25 microns to about 100 microns.

28. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size from about 35 microns to about 55 microns.

29. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 150 microns.

30. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 75 microns.

31. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 50 microns.

32. The composition for a magnetic composite of claim 18 wherein the magnetic powder has a mean particle size with a value of standard deviation less than about 20 microns.

33. The composition for a magnetic composite of claim 18 wherein the magnetic composite contains mold release agents selected from the group consisting of stearyl stearate, beeswax, montan wax, paraffin wax and combinations thereof.