Thermosetting film-forming recording layer composition and method therefor

Claim 2

A heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, comprising: a heat-curable epoxy polymer resin; magnetizable particles of less than about 2.0 microns in length substantially uniformly dispersed throughout said resin in an amount sufficient to impart magnetization capability thereto; about 1% to about 10% by weight of jojoba oil; and sufficient solvent to impart to said composition a viscosity of from about 200 to about 600 centipoise at about 24° C.

Claim 3

A composition according to claim 1 in which said jojoba oil comprises from about 2% to about 8% by weight, based on total dissolved solids.

Claim 4

A composition according to claim 1 further comprising a catalytically effective amount of a polymerization catalyst.

Claim 5

A composition according to claim 1 in which said epoxy resin has an epoxide equivalent weight of from about 165 to about 6000 and is combined with a cellulose acetate butyrate with a butyryl content of at least about 17%.

Claim 6

A composition according to claim 4 further comprising an effective amount of a catalyst selected from polyamine compounds having at least one primary amine per molecule and hydroxyl compounds.

Claim 7

A composition according to claim 1 further comprising from about 0.5% to about 7.5% by weight of substantially uniformly dispersed alumina particles.

Claim 8

A heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, comprising: a heat-curable polymer resin comprising about 10% to about 50% of an epoxy resin with an epoxide equivalent weight of from about 165 to about 6000 and about 1% to about 20% of a cellulose acetate butyrate with a butyryl content of at least about 17%; a polyamine polymerization catalyst having at least one primary amine per molecule, at a concentration such that the ratio of epoxide equivalents to amine equivalents is from about 1:4 to about 4:1; about 40% to about 85% of substantially uniformly dispersed magnetizable particles less than about 2.0 microns in length; about 1% to about 10% of jojoba oil; about 0.5% to about 7.5% of substantially uniformly dispersed alumina particles; and sufficient solvent to impart to said composition a viscosity of from about 200 to about 600 centipoise at about 24° C.; all said component percents being on a weight basis, based upon total dissolved solids.

Claim 9

A heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, comprising: a heat-curable polymer resin comprising about 10% to about 50% of an epoxy resin with an epoxide equivalent weight of from about 165 to about 6000 and about 1% to about 20% of a cellulose acetate butyrate with a butyryl content of at least about 17%; a polyamine polymerization catalyst having at least one primary amine per molecule, at a concentration such that the ratio of epoxide equivalents to amine equivalents is from about 1:4 to about 4:1; about 40% to about 85% of substantially uniformly dispersed magnetizable particles less than about 2.0 microns in length; about 1% to about 10% of jojoba oil; about 0.5% to about 7.5% of substantially uniformly dispersed alumina particles; and sufficient solvent to impart to said composition a viscosity of from about 200 to about 600 centipoise at about 24° C.; all said component percents being on a weight basis, based upon total dissolved solids.

Claim 10

A heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, comprising: a heat-curable polymer resin comprising about 20% to about 40% of an epoxy resin with an epoxide equivalent weight of from about 250 to about 1000 and about 2% to about 12% of a cellulose acetate butyrate with a butyryl content of at least about 17%; about 2% to about 5% of N-aminoethylpiperazine; about 50% to about 75% of substantially uniformly dispersed magnetizable particles less than about 2.0 microns in length; about 2% to about 8% jojoba oil; about 0.5% to about 7.5% of substantially uniformly dispersed alumina particles; and sufficient solvent to impart to said composition a viscosity of from about 200 to about 600 centipoise at about 24° C., all said component percents being on a weight basis, based upon total dissolved solids.

Claim 11

A heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, comprising: a heat-curable polymer resin comprising about 20% to about 40% of an epoxy resin with an epoxide equivalent weight of from about 250 to about 1000 and about 2% to about 12% of a cellulose acetate butyrate with a butyryl content of at least about 17%; about 2% to about 5% of N-aminoethylpiperazine; about 50% to about 75% of substantially uniformly dispersed magnetizable particles less than about 2.0 microns in length; about 2% to about 8% jojoba oil; about 0.5% to about 7.5% of substantially uniformly dispersed alumina particles; and sufficient solvent to impart to said composition a viscosity of from about 200 to about 600 centipoise at about 24° C., all said component percents being on a weight basis, based upon total dissolved solids.

Claim 12

A process for the preparation of a heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, said process comprising the steps of: (a) combining magnetizable particles of less than about 2.0 microns in length with an organic solution of a heat-curable epoxy polymer resin to form a substantially uniform dispersion in an amount sufficient to impart magnetization capability thereto upon curing; (b) combining said dispersion with about 1% to about 10% by weight jojoba oil; and (c) combining the product of step (b) with a catalytically effective amount of a polymerization catalyst.

Claim 13

A process for the preparation of a heat-hardenable liquid magnetizable film-forming composition for use in the preparation of rigid magnetic memory discs, said process comprising the steps of: (a) combining magnetizable particles of less than about 2.0 microns in length with an organic solution of a heat-curable epoxy polymer resin to form a substantially uniform dispersion in an amount sufficient to impart magnetization capability thereto upon curing; (b) combining said dispersion with about 1% to about 10% by weight jojoba oil; and (c) combining the product of step (b) with a catalytically effective amount of a polymerization catalyst.

Claim 14

A process according to claim 9 which further comprises combining of alumina particles with the components of step (a) to comprise from about 0.5% to about 7.5% by weight of said dispersion.

Claim 15

A process according to claim 9 in which sufficient organic solvent is included to provide a viscosity of from about 200 to about 600 centipoise at about 24° C.

Claim 16

A process according to claim 9 in which said polymer resin is a mixture of an epoxy resin with an epoxide equivalent weight of from about 165 to about 6000 and a cellulose acetate butyrate with a butyryl content of at least about 17%, said polymerization catalyst is N-aminoethylpiperazine, said composition further comprises from about 0.5% to about 7.5% by weight of alumina particles, and the viscosity of said composition is from about 200 to about 600 centipoise at about 24° C.

Claim 17

A process for forming a solid adherent magnetizable film on a rigid substrate, said process comprising applying to said substrate a composition according to claim 1 to form a thin film thereof of uniform thickness, and curing said film at elevated temperature to evaporate therefrom substantially all solvent and to form a solid adherent layer.