Patent US4234378A successfully refreshed from Google Patents.
US4234378A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnet paper sheet and a method for manufacturing the same
Assignee: Sakai Chemical Industry Co Ltd
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Filing: 1979-04-27
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Granted: 1980-11-18
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Expires: 1999-04-27
Abstract
Abstract An improved method for manufacturing a magnet paper sheet which comprises: thoroughly mixing about 70-90 parts by weight of magnetoplumbite barium ferrite powder and/or magnetoplumbite strontium ferrite powder essentially consisting of particles of primary particle size of about 0.1-2 microns and of secondary particle size smaller than about 20 microns, an anionic synthetic latex containing about 1-10 parts by weight in dry weight of a synthetic rubber and/or a synthetic resin such as SBR, NBR, polyvinyl acetate and polyacrylate, about 2-10 weight % of a cationic organic polymer electrolyte such as polyamine and polyethyleneimine based on the amount of the synthetic rubber and/or resin, and more than about 5 parts by weight of pulp fibers together into a slurry; forming the slurry into a paper sheet; and magnetizing the paper sheet.
Inventors
- 👤 Susumu Iwasaki
- 👤 Osamu Nagasawa
- 👤 Tatsuo Takano
- 👤 Seiji Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:10
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/46; D21H17/54; D21H17/56; D21H17/34; D21H17/35; D21H17/36; D21H17/37; D21H17/375; D21H17/55; D21H17/63; D21H17/67; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; H01F1/113; H01F1/117
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
201 words
A method for manufacturing a magnet paper sheet which comprises: (a) adding to a slurry of paper forming fiber about 70-90 parts by weight of at least one ferrite powder selected from the group consisting of magnetoplumbite barium ferrite and magnetoplumbite strontium ferrite essentially consisting of particles of a primary particle size of about 0.1-2 microns and of secondary particle size smaller than about 20 microns; (b) adding to the resultant slurry a cationic synthetic polymer electrolyte selected from the group consisting of a polyacrylamide, a polyamine, a polyamine-epichlohydrin condensation polymer and a polyethyleneimine; (c) then adding to the resultant slurry of step (b) an anionic synthetic latex containing about 1-10 parts by weight of a synthetic polymer selected from the group consisting of a styrene-butadine copolymer, an acrylonitrile-butadiene copolymer, a polyvinyl acetate a polyacrylate, an acrylate-butadiene copolymer, an acrylate-acrylonitrile copolymer, an acrylate-styrene copolymer, a vinyl acetate-acrylate copolymer, a polyvinyl chloride, and an ethylene-vinyl acetate copolymer; the amount of the cationic synthetic polymer electrolyte being about 2-10% by weight of the dry weight of the anionic synthetic polymer latex; (d) forming the thus obtained slurry into a paper sheet of about 0.1-2 mm in thickness; and (e) magnetizing the paper sheet.
Claim 2
Independent Claim
201 words
A method for manufacturing a magnet paper sheet which comprises: (a) adding to a slurry of paper forming fiber about 70-90 parts by weight of at least one ferrite powder selected from the group consisting of magnetoplumbite barium ferrite and magnetoplumbite strontium ferrite essentially consisting of particles of a primary particle size of about 0.1-2 microns and of secondary particle size smaller than about 20 microns; (b) adding to the resultant slurry a cationic synthetic polymer electrolyte selected from the group consisting of a polyacrylamide, a polyamine, a polyamine-epichlohydrin condensation polymer and a polyethyleneimine; (c) then adding to the resultant slurry of step (b) an anionic synthetic latex containing about 1-10 parts by weight of a synthetic polymer selected from the group consisting of a styrene-butadine copolymer, an acrylonitrile-butadiene copolymer, a polyvinyl acetate a polyacrylate, an acrylate-butadiene copolymer, an acrylate-acrylonitrile copolymer, an acrylate-styrene copolymer, a vinyl acetate-acrylate copolymer, a polyvinyl chloride, and an ethylene-vinyl acetate copolymer; the amount of the cationic synthetic polymer electrolyte being about 2-10% by weight of the dry weight of the anionic synthetic polymer latex; (d) forming the thus obtained slurry into a paper sheet of about 0.1-2 mm in thickness; and (e) magnetizing the paper sheet.
Claim 3
Dependent Claim
24 words
A method for manufacturing a magnet paper sheet as claimed in claim 1 wherein the styrene-butadiene copolymer contains about 40-70% by weight of styrene.
Claim 4
Dependent Claim
24 words
A method for manufacturing a magnet paper sheet as claimed in claim 1 wherein the acrylonitrile-butadiene copolymer contains about 25-45% by weight of acrylonitrile.
Claim 5
Dependent Claim
20 words
A method for manufacturing a magnet paper sheet as claimed in claim 2 wherein the copolymer contains carboxyl groups therein.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |