Magnetic recording medium

Claim 2

A magnetic recording medium comprising a substrate and a magnetic recording layer thereon comprising a cured binder and magnetic particles, the binder comprising the reaction product of a lactone-acrylate adduct with: (a) a multi-functional isocyanate; (b) a polyol and a multi-functional isocyanate; (c) a polyol, a multi-functional isocyanate, and a hydroxyalkyl acrylate; or (d) a polyol, a multi-functional isocyanate, a hydroxyalkyl acrylate and a reactive solvent.

Claim 3

A magnetic recording medium as defined in claim 1 wherein the lactone-acrylate adduct is prepared by reacting a lactone with an hydroxyalkyl acrylate.

Claim 4

A magnetic recording medium as defined in claim 2 wherein the lactone is characterized by the following formula: ##STR7## wherein the R's are independently hydrogen or alkyl of from 1 to 12 carbon atoms, and x is from 4 to 7.

Claim 5

A magnetic recording medium as defined in claim 3 wherein the lactone is epsilon-caprolactone.

Claim 6

A magnetic recording medium as defined in claim 2 wherein the hydroxyalkyl acrylate is selected from 2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-3-chloro-propylacrylate, 2,3-dihydroxy propyl acrylate, or mixtures thereof.

Claim 7

A magnetic recording medium as defined in claim 5 wherein the hydroxyalkyl acrylate is hydroxyethyl acrylate.

Claim 8

A magnetic recording medium as defined in claim 1 wherein the binder comprises the reaction product of a lactone-acrylate adduct with a multi-functional isocyanate.

Claim 9

A magnetic recording medium as defined in claim 7 wherein the multi-functional isocyanate is selected 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, di(2-isocyanatoethyl)-bicyclo (2.2.1) hept-5-ene-2,3-dicarboxylate, 3,5,5-triethyl-1-isocyanato-3-isocyanato-methylcyclohexane, 1,6-hexamethylene diisocyanate, m- and p-xylene diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexyl-4,4'-methane diisocyanate, tetramethylene diisocyanate, cyclopentylene-1,3-diisocyanate, 1,3-diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylbiphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethoxy 4,4'-dimethyl 4,4'-biphenylene diisocyanate, durene diisocyanate, 1-phenoxy-2,4-phenylene diisocyanate, 1-tert-butyl-2,4-phenylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,3,5-benzene triisocyanate, 2,4,6-toluene triisocyanate toluene, or mixtures thereof.

Claim 10

A magnetic recording medium as defined in claim 1 wherein the binder comprises the reaction product of a lactone-acrylate adduct with a multi-functional isocyanate and a polyol.

Claim 11

A magnetic recording medium as defined in claim 9 wherein the polyol is selected from the group consisting of a polyether polyol, a polycaprolactone polyol, a polyester polyol, an acrylic polyol, a vinyl polyol, a polymer/polyol, or mixtures thereof.

Claim 12

A magnetic recording medium as defined in claim 10 wherein the polyether polyol is selected from the group consisting of a propylene oxide polyol, an ethylene oxide polyol, a propylene oxide polyol capped with ethylene oxide, ethylene oxide/propylene oxide copolymers, a tetramethylene oxide polyol and a polymer/polyol.

Claim 13

A magnetic recording medium as defined in claim 9 wherein the polyol is a polymer polyol.

Claim 14

A magnetic recording medium as defined in claim 9 wherein the polyol is a polyepsilon-caprolactone polyol.

Claim 15

A magnetic recording medium as defined in claim 9 wherein the polyol is a polyester polyol.

Claim 16

A magnetic recording medium as defined in claim 9 wherein the polyol is an acrylic polyol.

Claim 17

A magnetic recording medium as defined in claim 9 wherein the polyol is a vinyl polyol.

Claim 18

A magnetic recording medium as defined in claim 1 wherein the binder comprises the reaction product of a lactone-acrylate adduct with a polyol, a multifunctional isocyanate and an hydroxyalkyl acrylate.

Claim 19

A magnetic recording medium as defined in claim 17 wherein the hydroxyalkyl acrylate is as defined in claim 5.

Claim 20

A magnetic recording medium as defined in claim 1 wherein the binder comprises the reaction product of a lactone-acrylate adduct with a polyol, a multifunctional isocyanate, and an hydroxyalkyl acrylate in a reactive solvent.

Claim 21

A magnetic recording medium as defined in claim 19 wherein the reactive solvent is of the following formula: ##STR8## wherein X is hydrogen or methyl and R 2 can be substituted or unsubstituted alkyl, cycloalkyl, alkenyl, aryl, or aralkyl, wherein the substituent can be alkyoxy, hydroxyl, cyano, or amino, or R 2 can be carbamoyloxy alkyl which can be N-alkyl substituted.

Claim 22

A magnetic recording medium as defined in claim 19 wherein the reactive solvent is a multi-functional alkyl acrylate.

Claim 23

A magnetic recording medium as defined in claim 21 wherein the reactive solvent is 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetramethyleneglycol diacrylate, esterdiol-204-diacrylate, trimethylolpropane triacrylate, triethyleneglycol diacrylate, the diacrylate of esterdiol 204, or mixtures thereof.

Claim 24

A magnetic recording medium as defined in claim 19 wherein the reactive solvent is N-vinylpyrrolidone.

Claim 25

A magnetic recording medium as defined in claim 19 wherein the reactive solvent is a lactone-acrylate adduct reacted with a multi-functional isocyanate.

Claim 26

A magnetic recording medium as defined in claims 1 or 7 or 9 or 17 or 19 which contains a non-reactive solvent.

Claim 27

A magnetic recording medium as defined in claim 24 wherein the solvent is cyclohexanone, toluene, methyl isobutyl ketone, tetrahydrofuran, methyl amyl ketone, ethoxy ethyl acetate, and mixtures thereof.

Claim 28

A magnetic recording medium as defined in claims 1 or 7 or 9 or 17 or 19 or 25 which contains the reaction product of a polyol, a multi-functional isocyanate and an hydroxyalkyl acrylate and/or the reaction product of an hydroxyalkyl acrylate and multi-functional isocyanate.