Magnetic tape

Claim 2

In a magnetic recording tape of the type comprising a backing film and a magnetic coating thereon wherein said coating is formed of iron oxide magnetic particles within a resinous matrix therefor, the improvement wherein a. the matrix resin comprises at least about 50% by weight of a poly-urethane elastomer resin characterized by a minimum elongation of about 400%, a minimum tensile strength of 6000 psi, and a minimum 300% modulus of about 1200 psi, and comprises fromabout 0 to 50% by weight of a supplemental resin; and b. wherein said magnetic coating comprises said iron oxide particles having an oil absorption value of less than 50 ml per 100 grams; wherein said magnetic coating has properties including a minimum tensile strength of about 1100 psi; a minimum elongation of about 10%; and a minimum toughness of about 100 inch-pounds per cubic inch; all said properties of said coating being measured when said coatings consists essentially of, in addition to the matrix resin, (a) at least 70% by weight of an acicular gamma Fe 2 O 3 particle of a 0.5 micron length and an oil absorption of at least 25 ml per 100 grams (b) at least 3.5% by weight of carbon black having a surface area of about 230 square meters per gram and a di-butyl phthalate absorption of 185 cc per gram.

Claim 3

A magnetic tape as defined in claim 1 wherein said resinous matrix comprises polyurethane having a tensile strength of 10,000 psi, an elongation is excess of 400%, and 300% modulus in excess of 3500 psi.

Claim 4

A magnetic tape as defined in claim 1 wherein said resinous matrix is a thermoplastic consistisng essentially of said polyurethane, and a linear thermoplastic polyester which is characterized by a minimum elongation of 150%, and a thermoplastic phenoxy resin of the formula ##STR8## wherein n is from 80 to 120.

Claim 5

A magnetic tape as defined in claim 1 comprising, additionally, polymeric linkages derived from polymeric isocyanate crosslinking having up to 20% by weight of reactive, NCO groups therein, and incorporated into said resinous matrix in a quantity of from about 0.5 to 3% by weight.

Claim 6

A magnetic tape as defined in claim 2 comprising, additionally, polymeric linkages derived from polymeric isocyanate crosslinking having up to 20% by weight of reactive NCO groups therein, and incorporated into said binder in a quantity of from about 0.5 to 3% by weight.

Claim 7

A magnetic tape as defined in claim 3 comprising, additionally polymeric linkages derived from polymeric isocyanate crosslinking having up to 20% by weight of reactive NCO groups therein, and incorporated into said binder in a quantity of from about 0.5 to 3% by weight.

Claim 8

A magnetic tape as defined in claim 4 wherein said binder consists essentially of an ether-tape polyurethane and said supplemental resin comprises a major portion of a polyalkylene glycol resin having a molecular weight of at least 1800 and a hydroxyl number below 100.

Claim 9

A magnetic tape as defined in claim 1 and further characterized by a Video Durability Test Value of at least one hour and Shuttle Test Value of at least 30,000 passes.

Claim 10

A magnetic tape as defined in claim 2 and further characterized by a Video Durability Test Value of at least one hour and a Shuttle Test Value of at least 30,000 passes.

Claim 11

A magnetic tape as defined in claim 3 and further characterized by a Video Durabiity Test Value of at least one hour and a Shuttle Test Value of at least 30,000 passes.

Claim 12

A magnetic tape as defined in claim 6 and further characterized by a Video Durability Test Value of at least one hour and a Shuttle Test Value of at least 30,000 passes.

Claim 13

In a magnetic recording tape of the type comprising a backing film and a magnetic coating thereon wherein said coating is formed of magnetic particles within a resinous matrix therefor, the improvement wherein the matrix resin is substantially free of crosslinking, comprises less than about 7.5% by weight of wetting agents, a. comprises at least about 50% by weight of a polyurethane elastomer resin characterized by a minimum elongation of about 400%, a minimum tensile strength of 6000 psi, and a minimum 300% modulus of about 1200psi, and from about 0 to 50% by weight of a supplemental resin; and b. wherein said magnetic coating comprises iron oxide having an oil absorption value of less than 50 ml per 100 grams; and c. wherein said magnetic coating has properties including a minimum tensile strength of about 1100 psi; a minimum elongation of about 10%; and a minimum toughness of about 100 inch-pounds per cubic inch; all said properties of said coating being measured when said coating consists essentially of, in addition to the matrix, (1) at least 70% by weight of an acicular gamma Fe 2 O 3 particle of a 0.5 micron length and an oil absorption of at least 25 ml per 100 grams and (2) at least 3.5% by weight of carbon black having a surface area of about 230 square meters per gram and a di-butyl phthalate absorption.

Claim 14

In a magnetic recording tape of the type comprising a backing film and a magnetic coating thereon wherein said coating is formed of magnetic particles within a resinous matrix therefor, the improvement wherein the matrix resin is substantially free of crosslinking, comprises less than about 7.5% by weight of wetting agents, a. comprises at least about 50% by weight of a polyurethane elastomer resin characterized by a minimum elongation of about 400%, a minimum tensile strength of 6000 psi, and a minimum 300% modulus of about 1200psi, and from about 0 to 50% by weight of a supplemental resin; and b. wherein said magnetic coating comprises iron oxide having an oil absorption value of less than 50 ml per 100 grams; and c. wherein said magnetic coating has properties including a minimum tensile strength of about 1100 psi; a minimum elongation of about 10%; and a minimum toughness of about 100 inch-pounds per cubic inch; all said properties of said coating being measured when said coating consists essentially of, in addition to the matrix, (1) at least 70% by weight of an acicular gamma Fe 2 O 3 particle of a 0.5 micron length and an oil absorption of at least 25 ml per 100 grams and (2) at least 3.5% by weight of carbon black having a surface area of about 230 square meters per gram and a di-butyl phthalate absorption.

Claim 15

A magnetic tape as defined in claim 12 wherein said resinous matrix comprises polyurethane having a tensile strength of 10,000 psi, an elongation in excess of 400% and a 300% modulus in excess of 3500 psi.

Claim 16

A magnetic tape as defined in claim 13 wherein said binder is a thermoplastic consisting essentially of said polyurethane, and a linear thermoplastic polyester which is characterized by a minimum elongation of 150%, and a thermoplstic phenocy resin of the formula ##STR9## wherein n is from 80 to 120.

Claim 17

A magnetic tape as define in claim 14 comprising additionally, polymeric linkages derived from polymeric isocyanate crosslinking having up to 20% by weight of reactive NCO groups therein, and incorporated into said binder in a quantity of from about 0.5 to 3% by weight.

Claim 18

A magnetic tape as defined in claim 13 and further characterized by a Video Durability Test Value of at least one hour and a Shuttle Test Value of at least 30,000 passes.

Claim 19

A magnetic tape as defined in claim 14 and further characterized by a Video Durability Test Value of at least one hour and a Shuttle Test Value of at least 30,000 passes.

Claim 20

In a magnetic recording tape of the type comprising a backing film and a magnetic coating thereon wherein said coating is formed of magnetic iron oxide particles within a resinous matrix therefor, the improvement wherein the matrix resin is a thermoplastic and comprises at least about 50% by weight of a polyurethane elastomer resin, free of crosslinking agent, and characterized by a 300% modulus of at least about 1500, a minimum elongation of about 400%, a minimum tensile strength of 6000 psi, and from about 0 to 50% by weight of a supplemental resin; and wherein said magnetic coating has properties including a minimum tensile strength of about 1100 psi; a minimum elongation of about 10%; and a minimum toughness of about 100 inch-pounds per cubic inch; all said properties of said coating being measured when said coating consists essentially of, in addition to the matrix, (a) at least 70% by weight of an acicular gamma Fe 2 O 3 particles of a 0.5 micron length and an oil absorption of at least 25 ml per 100 grams and (b) at least 3.5% by weight of carbon black having a surface area of about 230 square meters per gram and di-butyl phthalate absorption of 185 cc per gram.

Claim 21

In a magnetic recording tape of the type comprising a backing film and a magnetic coating thereon wherein said coating is formed of magnetic iron oxide particles within a resinous matrix therefor, the improvement wherein the matrix resin is a thermoplastic and comprises at least about 50% by weight of a polyurethane elastomer resin, free of crosslinking agent, and characterized by a 300% modulus of at least about 1500, a minimum elongation of about 400%, a minimum tensile strength of 6000 psi, and from about 0 to 50% by weight of a supplemental resin; and wherein said magnetic coating has properties including a minimum tensile strength of about 1100 psi; a minimum elongation of about 10%; and a minimum toughness of about 100 inch-pounds per cubic inch; all said properties of said coating being measured when said coating consists essentially of, in addition to the matrix, (a) at least 70% by weight of an acicular gamma Fe 2 O 3 particles of a 0.5 micron length and an oil absorption of at least 25 ml per 100 grams and (b) at least 3.5% by weight of carbon black having a surface area of about 230 square meters per gram and di-butyl phthalate absorption of 185 cc per gram.

Claim 22

A recording tape as defined in claim 18 wherein said magnetic particles have an oil abosrption value of over 75 ml per 100 grams of particle.