Magnetic recording medium and magnetic recording medium composition

Patent metadata

Field	Value
Publication number	US-2017287518-A1
Application number	US-201715474504-A
Country	US
Kind code	A1
Filing date	Mar 30, 2017
Priority date	Mar 31, 2016
Publication date	Oct 5, 2017
Grant date	—

Abstract

The magnetic recording medium contains, in a magnetic layer, a fatty acid ester and a polyester resin having a number average molecular weight of greater than or equal to 1,000 but less than 20,000, and containing a structural unit derived from a polyvalent carboxylic acid and a structural unit derived from a polyol, as well as 10 mol % to 50 mol % of a structural unit, derived from a cyclic polyvalent carboxylic acid selected from the group consisting of an alicyclic polyvalent carboxylic acid and an aromatic polyvalent carboxylic acid, per 100 mol % of a combined total of the above structural units, and one or more partial structures selected from the group consisting of the following partial structures:

wherein each of L 1 and L 2 independently denotes a divalent connecting group, and each of Z 1 and Z 2 independently denotes a monovalent group denoted by —OM or a monovalent group denoted by —O − A + .

First claim

What is claimed is:

1 . A magnetic recording medium,
which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein: the magnetic layer further comprises a fatty acid ester and a polyester resin with a number average molecular weight of greater than or equal to 1,000 but less than 20,000; the polyester resin comprises a structural unit derived from a polyvalent carboxylic acid and a structural unit derived from a polyol, as well as 10 mol % to 50 mol % of a structural unit, derived from a cyclic polyvalent carboxylic acid selected from the group consisting of an alicyclic polyvalent carboxylic acid and an aromatic polyvalent carboxylic acid, per 100 mol % of a combined total of the structural unit derived from the polyvalent carboxylic acid and the structural unit derived from the polyol; and the polyester resin comprises one or more partial structures selected from the group consisting of a partial structure denoted by formula 1 and a partial structure denoted by formula 2 below:

wherein each of L 1 in formula 1 and L 2 in formula 2 independently denotes a divalent connecting group, and each of Z 1 in formula 1 and Z 2 in formula 2 independently denotes a monovalent group denoted by —OM or a monovalent group denoted by —O − A + , with M denoting a hydrogen atom or an alkali metal atom, A + denoting an ammonium cation, and * denoting a bond position with another partial structure constituting the polyester resin.

2 . The magnetic recording medium according to claim 1 ,
wherein the divalent connecting group is an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or an aromatic group having 6 to 12 carbon atoms.

3 . The magnetic recording medium according to claim 1 ,
wherein the divalent connecting group is an alkylene group having 1 to 10 carbon atoms.

4 . The magnetic recording medium according to claim 1 ,
wherein the divalent connecting group is an alkenylene group having 2 to 10 carbon atoms.

5 . The magnetic recording medium according to claim 1 ,
wherein the divalent connecting group is an aromatic group having 6 to 12 carbon atoms.

6 . The magnetic recording medium according to claim 1 ,
wherein the magnetic layer comprises 0.5 to 50.0 weight parts of the polyester resin per 100.0 weight parts of ferromagnetic powder.

7 . The magnetic recording medium according to claim 1 ,
wherein the binder is one or more resins selected from the group consisting of a polyurethane resin and a vinyl chloride resin.

8 . The magnetic recording medium according to claim 1 ,
wherein an average particle size of the ferromagnetic powder falls within a range of 10 nm to 50 nm.

9 . A composition,
which is a magnetic recording medium composition comprising ferromagnetic powder, binder, a fatty acid ester, and a polyester resin with a number average molecular weight of greater than or equal to 1,000 but less than 20,000, wherein: the polyester resin comprises a structural unit derived from a polyvalent carboxylic acid and a structural unit derived from a polyol, as well as 10 mol % to 50 mol % of a structural unit, derived from a cyclic polyvalent carboxylic acid selected from the group consisting of an alicyclic polyvalent carboxylic acid and an aromatic polyvalent carboxylic acid, per 100 mol % of a combined total of the structural unit derived from the polyvalent carboxylic acid and the structural unit derived from the polyol; and the polyester resin comprises one or more partial structures selected from the group consisting of a partial structure denoted by formula 1 and a partial structure denoted by formula 2 below:

wherein each of L 1 in formula 1 and L 2 in formula 2 independently denotes a divalent connecting group, and each of Z 1 in formula 1 and Z 2 in formula 2 independently denotes a monovalent group denoted by —OM or a monovalent group denoted by —O − A + , with M denoting a hydrogen atom or an alkali metal atom, A + denoting an ammonium cation, and * denoting a bond position with another partial structure constituting the polyester resin.

10 . The composition according to claim 9 ,
wherein the divalent connecting group is an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or an aromatic group having 6 to 12 carbon atoms.

11 . The composition according to claim 9 ,
wherein the divalent connecting group is an alkylene group having 1 to 10 carbon atoms.

12 . The composition according to claim 9 ,
wherein the divalent connecting group is an alkenylene group having 2 to 10 carbon atoms.

13 . The composition according to claim 9 ,
wherein the divalent connecting group is an aromatic group having 6 to 12 carbon atoms.

14 . The composition according to claim 9 ,
which comprises 0.5 to 50.0 weight parts of the polyester resin per 100.0 weight parts of ferromagnetic powder.

15 . The composition according to claim 9 ,
wherein the binder is one or more resins selected from the group consisting of a polyurethane resin and a vinyl chloride resin.

16 . The composition according to claim 9 ,
wherein an average particle size of the ferromagnetic powder falls within a range of 10 nm to 50 nm.

Assignees

• Fujifilm Corp

Inventors

• Aoshima Toshihide
• Imamura Mika
• Tsujimoto Shinji

Classifications

• C08K2003/2272

  Ferric oxide (Fe2O3) · CPC title

• C08K5/101

  of monocarboxylic acids · CPC title

• G11B5/7021

  containing a polyurethane or a polyisocyanate · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/7023

  containing polyesters, polyethers, silicones, polyvinyl resins, polyacrylresins or epoxy resins (G11B5/7022 takes precedence) · CPC title