MAGNETIC RECORDING MEDIUM AND RADIATION CURING COMPOSITION

• US 20080152956A1
• Filed: 12/19/2007
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: NAKAI, Yoshihiro, MURAYAMA, Yuichiro, HASHIMOTO, Hiroshi
• Application Number:
  US11/959,989
• Publication Number:
  US 20080152956A1
• Time in Patent Office: Days
• US Class Current: 428/840
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/7026 Radiation curable polymers
• CPC Class Codes: G11B 5/73 Base layers , i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
• CPC Class Codes: G11B 5/733 characterised by the addition of non-magnetic particles base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739
• CPC Class Codes: G11B 5/73927 Polyester substrates, e.g. polyethylene terephthalate
• CPC Class Codes: G11B 5/73929 comprising naphthalene ring compounds, e.g. polyethylene naphthalate substrates

Abstract

A magnetic recording medium is provided that comprises a non-magnetic support and, in order thereabove, a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation and a magnetic layer comprising a ferromagnetic powder dispersed in a binder, the radiation curing compound being a compound having a carbonate bond. There is also provided a radiation curing composition comprising a radiation curing compound having a carbonate bond.

Claims

1. A magnetic recording medium comprising:

a non-magnetic support and, in order thereabove;

a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation; and

a magnetic layer comprising a ferromagnetic powder dispersed in a binder;

the radiation curing compound being a compound having a carbonate bond.

2. The magnetic recording medium according to claim 1, wherein the radiation curing compound is a compound having a carbonate bond, a radiation curing group, and an alicyclic skeleton.

3. The magnetic recording medium according to claim 1, wherein the radiation curing compound is a compound obtained by reacting a polycarbonate diol having an alicyclic skeleton with a carboxylic acid having an ethylenically unsaturated group.

4. The magnetic recording medium according to claim 2, wherein the radiation curing compound has a (meth)acryloyl group as a radiation curing group and has a radiation curing group content in the radiation curing compound of 0.5 mmol/g to 3.0 mmol/g.

5. The magnetic recording medium according to claim 1, wherein it comprises, between the radiation-cured layer and the magnetic layer, a non-magnetic layer comprising a non-magnetic powder dispersed in a binder.

6. The magnetic recording medium according to claim 1, wherein the radiation curing compound has a molecular weight of 1,000 to 5,000.

7. The magnetic recording medium according to claim 2, wherein the alicyclic skeleton is at least one alicyclic skeleton selected from the group consisting of a cycloalkane skeleton, a bicycloalkane skeleton, a tricycloalkane skeleton, a hydrogenated naphthalene skeleton, and a norbornane skeleton.

8. The magnetic recording medium according to claim 7, wherein the alicyclic skeleton is a cyclohexane skeleton or a tricyclodecane skeleton.

9. The magnetic recording medium according to claim 3, wherein the polycarbonate diol having an alicyclic skeleton is a polycarbonate diol derived from at least one diol selected from the group consisting of cyclohexanedimethanol, tricyclodecanedimethanol, and a hydrogenated dimer diol.

10. The magnetic recording medium according to claim 1, wherein the non-magnetic support is selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polyamide.

11. The magnetic recording medium according to claim 1, wherein it has a coefficient of hygroscopic expansion of 0 to 10 ppm/% RH at humidities between 10% RH to 90% RH

12. The magnetic recording medium according to claim 1, wherein the magnetic layer has a center line surface roughness Ra of 2.0 nm or less.

13. A radiation curing composition comprising:

a radiation curing compound having a carbonate bond.

14. The radiation curing composition according to claim 13, wherein it is used for a radiation-cured layer provided above a non-magnetic support of a magnetic recording medium.