MANUFACTURE OF MAGNETIC PARTICLES BY ELECTRODEPOSITION OF IRON, COBALT, OR NICKEL IN DIALKYL SULFOXIDE
First Claim
Patent Images
2. A method as claimed in claim 1 wherein said dialkyl sulfoxide is dimethyl sulfoxide.
0 Assignments
0 Petitions
Accused Products
Abstract
The invention relates to the preparation of fine ferromagnetic particles by electrodeposition of iron, nickel, cobalt, or mixtures of these metals, in a dialkyl sulfoxide bath, such as dimethyl sulfoxide, the particles produced at the electrode being removed at desired intervals. Heat-stable organic binders may be dissolved in the plating bath during electrodeposition to coat the formed particles and thereby inhibit surface oxidation and agglomeration. The particles are oblong in shape and, coated or uncoated, are especially useful for magnetic recording media, magnetic cores, magnetically responsive fluid suspensions and permanent magnets.
22 Citations
25 Claims
-
2. A method as claimed in claim 1 wherein said dialkyl sulfoxide is dimethyl sulfoxide.
-
3. A method as claimed in claim 2 wherein the magnetic metal salt is selected from the group consisting of salts of iron, nickel, cobalt, and mixtures thereof.
-
4. A method as claimed in claim 2 wherein the current source is DC and the metal particles are removed from the cathode.
-
5. A method as claimed in claim 2 wherein the metal particles are removed by washing the electrodes at which electrodeposition occurs.
-
6. A method as claimed in claim 2 wherein the metal particles are removed by immersing the electrodes at which electrodeposition occurs in an ultrasonic field.
-
7. A method as claimed in claim 2 wherein the current source is AC and magnetic particle electrodeposition occurs at and particles are removed from both the anode and cathode electrode elements.
-
8. A method as claimed in claim 2 wherein a binder consisting of flexible heat-stable film-forming organic polymer is dissolved in the electrodeposition bath to coat around the metal particles to prevent their agglomeration and oxidation.
-
9. A method as claimed in claim 8 wherein the heat-stable film-forming organic polymer is selected from the group consisting of copolymers of acrylonitrile and styrene, copolymers if acrylonitrile and butadiene, acrylate and styrene copolymers, aromatic Polycarbonates, polyacrylic esters, polyphenyl ether, polyamides, polyesters, polyarylimides, cellulose ester, cellulose ether, vinyl chloride polymers, epoxy resin, silicone resin, fluorinated resins, polyesters of aromatic acids and polyesters reacted with blocked polyisocyanates.
-
10. A method as claimed in claim 2 wherein a shape-modifying additive, selected from the group consisting of sucrose, sodium saccharin and biphenyl, is added to the dimethyl sulfoxide bath prior to electroplating.
-
11. A method as claimed in claim 7 wherein the anode and cathode elements are formed of the same metal as the dissolved metal salts.
-
12. A method of manufacturing magnetic recording media comprising:
- preparing an electrodeposition bath wherein a salt of a magnetic metal is dissolved in a dialkyl sulfoxide bath;
providing an anode and a solid cathode electrode elements for said bath;
connecting an electric current source to said anode and cathode electrode elements;
removing the metal particles electrodeposited on said electrode elements;
adding a heat-stable film-forming flexible binder to said magnetic particles in a volatile organic solvent for the binder to form a dispersion;
coating a base with said dispersion; and
drying the coating.
- preparing an electrodeposition bath wherein a salt of a magnetic metal is dissolved in a dialkyl sulfoxide bath;
-
13. An electrolytic bath for electrodeposition of iron, nickel, cobalt or mixtures in particle size of from about 0.03 to 0.8 micron consisting essentially of:
- a dialkyl sulfoxide; and
a water-soluble salt of a magnetic metal selected from the group consisting of iron, nickel, cobalt and mixtures thereof which is dissolved therein.
- a dialkyl sulfoxide; and
-
14. An electrolytic bath as claimed in claim 12, wherein said dialkyl sulfoxide is dimethyl sulfoxide.
-
15. The composition of claim 14 wherein the salt of a magnetic meal is selected from the group consisting of salts of iron, nickel, cobalt, and mixtures thereof.
-
16. The composition of claim 14 wherein a heat-stable film-forming organic polymer is dissolved in the electrodeposition bath to coat around the metal particles to prevent their agglomeration and oxidation.
-
17. The composition of claim 16 wherein the heat-stable film-forming organic polymer is selected from the group consisting of copolymers of acrylonitrile and styrene, copolymers of acrylonitrile and butadiene, acrylate and styrene copolymers, aromatic polycarbonates, polyacrylic esters, polyphenyl ether, vinyl chloride polymers, epoxy resin, silicone resin, fluorinated resins, and polyesters, including polyesters of aromatic acids and polyester reacted with blocked polyisocyanates.
-
18. The composition of claim 14 wherein a shape-modifying additive, selected from the group consisting of sucrose, sodium saccharin and biphenyl, is added to the dimethyl sulfoxide bath prior to electroplating.
-
19. Finely divided ferromagnetic particles having a size of between about 0.03 to 0.8 micron, electrodeposited from dialkyl sulfoxide and having an oblong shape, said particles having a core consisting of metal selected from the group consisting of iron, nickel, cobalt, and mixtures of these and having a surface which contains an oxide of the core metal.
-
20. Finely divided ferromagnetic particles as claimed in claim 19 which are coated with a film-forming, heat-stable organic binder selected from the group consisting of copolymers of acrylonitrile and styrene, copolymers of acrylonitrile and butadiene, acrylate and styrene copolymers, aromatic polycarbonates, polyacrylic esters, polyphenyl ether, polyamides, polyarylimides, cellulose ester, cellulose ether, vinyl chloride polymers, epoxy resin, silicone resin, fluorinated resins, and polyesters, including polyesters of aromatic acids and polyesters reacted with blocked polyisocyanates.
-
21. Finely divided ferromagnetic particles as claimed in claim 19, wherein said particles are reduced in reducing gas at elevated temperatures to convert the surface oxide to pure metal.
-
22. Finely divided ferromagnetic particles as Claimed in claim 19, wherein said particle core consists of Alpha -iron and the particle surface is magnetite.
-
23. Finely divided ferromagnetic particles as claimed in claim 19, wherein said particle core consists of iron and cobalt and the particle surface includes magnetite.
-
24. Finely divided ferromagnetic particles as claimed in claim 19, wherein said particle core consists of iron, nickel and cobalt and the particle surface includes magnetite.
-
25. A method of manufacturing magnetic recording media comprising:
- dissolving a metal salt of iron, nickel, cobalt, and mixtures thereof in a dialkyl sulfoxide bath;
electrodepositing oblong particles of a size of about 0.03 to 0.8 micron;
dispersing a heat-stable, flexible, film-forming binder in the bath to coat said particles and to prevent their agglomeration and oxidation;
removing the coated particles;
adding a solvent for the film-forming binder to the coated particles to form a dispersion;
coating a base with said dispersion; and
drying the coating.
- dissolving a metal salt of iron, nickel, cobalt, and mixtures thereof in a dialkyl sulfoxide bath;
Specification