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US4046932A Expired / Lapsed US ⏱️ 0.0 years remaining

Magnetic recording discs

Assignee: BASF SE
•
Filing: 1976-02-09
•
Granted: 1977-09-06
•
Expires: 1996-02-09
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Abstract

Abstract The invention relates to a process for the manufacture of improved magnetic discs by applying a thin layer of a liquid dispersion of magnetic pigments and optionally further, non-magnetic, pigments in a binder mixture to a non-magnetic rigid base, and curing the magnetic coating which has been applied. The binder used is a mixture of polycondensates comprising 60 to 70% by weight of a solid curable polycondensate of 2,2-bis(4-hydroxyphenyl)-propane and epichlorohydrin having an epoxy equivalent weight from about 400 to 2,500 and a melting point from about 50° to 150° C, 10 to 30% by weight of a curable allyloxybenzene-formaldehyde condensate of the resol type with free methylol groups or with methylol groups etherified with a lower alcohol, and having a molecular weight of less than 1,000, and 10 to 30% by weight of a curable melamine-formaldehyde condensate with more than two methylol groups etherified with n-butanol or iso-butanol, and having a molecular weight of less than 2,500. A magnetic dispersion using such a binder allows the application of a firmly adhering magnetic coating, even in thicknesses of less than 4 μ, to aluminum discs or pre-coated aluminum discs, and the magnetic coating produced has high resistance to mechanical wear.

Inventors

  • 👤 Hans-Joerg Hartmann
  • 👤 Roland Falk
  • 👤 Peter Gawlik
  • 👤 Werner Balz
  • 👤 Karl Uhl
  • 👤 Dieter Schaefer
  • 👤 Herbert Motz

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 10:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7023; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/254; Y10T428/256; Y10T428/257; Y10T428/26; Y10T428/269; Y10T428/31504; Y10T428/31511; Y10T428/31529

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 143 words
A magnetic recording disc which comprises a base and an adhesive magnetic coating composition thereon, said coating comprising a binder and finely divided magnetic pigment dispersed in said binder, said binder comprising a mixture of polycondensates consisting essentially of A. 60 to 70% by weight of a solid curable polycondensate of 2,2-bis-(4-hydroxyphenyl)-propane and epichlorohydrin, with and epoxy equivalent weight from about 400 to 2,500 and having a melting point from about 50° to 150° C., B. 10 to 30% by weight of a curable allyloxybenzene-formaldehyde condensate of the resol type with free methylol groups or methylol groups etherified with a lower alcohol, and having a molecular weight of less than 1,000, and C. 10 to 30% by weight of a curable melamine-formuladehyde condensate with more than two methylol groups etherified with n-butanol or isobutanol and having a molecular weight of less than 2,500.
Claim 2
Dependent Claim 143 words
A magnetic recording disc which comprises a base and an adhesive magnetic coating composition thereon, said coating comprising a binder and finely divided magnetic pigment dispersed in said binder, said binder comprising a mixture of polycondensates consisting essentially of A. 60 to 70% by weight of a solid curable polycondensate of 2,2-bis-(4-hydroxyphenyl)-propane and epichlorohydrin, with and epoxy equivalent weight from about 400 to 2,500 and having a melting point from about 50° to 150° C., B. 10 to 30% by weight of a curable allyloxybenzene-formaldehyde condensate of the resol type with free methylol groups or methylol groups etherified with a lower alcohol, and having a molecular weight of less than 1,000, and C. 10 to 30% by weight of a curable melamine-formuladehyde condensate with more than two methylol groups etherified with n-butanol or isobutanol and having a molecular weight of less than 2,500.
Claim 3
Dependent Claim 28 words
A magnetic recording disc as set forth in claim 1 wherein said base is a non-magnetic, metallic disc selected from the group consisting of aluminum and aluminum alloy.
Claim 4
Dependent Claim 25 words
A magnetic recording disc as set forth in claim 2 wherein said disc has a polished, hard intermediate layer of a coating resin containing pigment.
Claim 5
Dependent Claim 39 words
A magnetic recording disc as set forth in claim 1 wherein said binder contains from 5 to 20% by weight, based on the sum of the amounts of the resins in A, B, and C of polyvinyl methyl ether.
Claim 6
Dependent Claim 21 words
A magnetic recording disc as set forth in claim 1 wherein said magnetic pigment is magnetite (Fe 3 O 4 ).
Claim 7
Dependent Claim 27 words
A magnetic recording disc as set forth in claim 1 wherein said magnetic pigment is acicular gamma-iron-(III) oxide with average particle size from about 0.1 to 2μ.

References Cited (Backward Citations)

US3366505A Cited
US3320090A Cited
US3689317A Cited
US3474073A Cited
US3560388A Cited
US3647539A Cited
US3821025A Cited
US3781210A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1980-09-05 1981-03-07 1981-09-06 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1984-09-05 1985-03-07 1985-09-06 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1988-09-05 1989-03-07 1989-09-06 $7700.00 Window Closed / Lapsed

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