Magnetic recording medium and cartridge

Patent metadata

Field	Value
Publication number	US-2022172742-A1
Application number	US-201916651542-A
Country	US
Kind code	A1
Filing date	Oct 2, 2019
Priority date	Aug 21, 2019
Publication date	Jun 2, 2022
Grant date	—

Abstract

A magnetic recording medium is a tape-shaped magnetic recording medium, including: a substrate; an underlayer provided on the substrate; and a magnetic layer provided on the underlayer. The substrate contains polyester, each of the underlayer and the magnetic layer contains a lubricant, the magnetic layer has a surface on which a large number of holes is provided, the arithmetic average roughness Ra of the surface is 2.5 nm or less, a BET specific surface area of the entire magnetic recording medium measured in a state where the magnetic recording medium has been washed and dried is 3.5 m2/g or more and 7.0 m2/g or less, a squareness ratio of the magnetic layer in a vertical direction is 65% or more, an average thickness of the magnetic layer is 80 nm or less, an average thickness of the magnetic recording medium is 5.6 μm or less, and a servo pattern is recorded on the magnetic layer and a statistical value δSW indicating a non-linearity of the servo pattern is 24 nm or less.

First claim

1 . A tape-shaped magnetic recording medium, comprising:
a substrate; an underlayer provided on the substrate; and a magnetic layer provided on the underlayer, wherein the substrate contains polyester, each of the underlayer and the magnetic layer contains a lubricant, the magnetic layer has a surface on which a large number of holes is provided, the arithmetic average roughness Ra of the surface is 2.5 nm or less, a BET specific surface area of the entire magnetic recording medium measured in a state where the magnetic recording medium has been washed and dried is 3.5 m 2 /g or more and 7.0 m 2 /g or less, a squareness ratio of the magnetic layer in a vertical direction is 65% or more, an average thickness of the magnetic layer is 80 nm or less, an average thickness of the magnetic recording medium is 5.6 μm or less, and a servo pattern is recorded on the magnetic layer and a statistical value σ SW indicating a non-linearity of the servo pattern is 24 nm or less.

2 . The magnetic recording medium according to claim 1 , wherein
the statistical value σ SW is 23 nm or less.

3 . The magnetic recording medium according to claim 1 , wherein
the statistical value σ SW is 20 nm or less.

4 . The magnetic recording medium according to claim 1 , wherein
the squareness ratio is 70% or more.

5 . The magnetic recording medium according to claim 1 , wherein
the arithmetic average roughness Ra is 2.2 nm or less.

6 . The magnetic recording medium according to claim 1 , wherein
a friction coefficient ratio (μ B /μ A ) between a dynamic friction coefficient μ A between the surface the magnetic layer and a magnetic head when tension applied to the magnetic recording medium is 1.2 N, and a dynamic friction coefficient μ B between the surface of the magnetic layer and the magnetic head when tension applied to the magnetic recording medium is 0.4 N is 1.0 or more and 2.0 or less.

7 . The magnetic recording medium according to claim 1 , wherein
regarding the dynamic friction coefficient μ C between the surface of the magnetic layer and a magnetic head when tension applied to the magnetic recording medium is 0.6 N, a friction coefficient ratio (μ C (1000)/μ C (5)) of a dynamic friction coefficient μ C (1000) of the 1000th travelling to a dynamic friction coefficient μ C (5) of the fifth travelling is 1.0 or more and 2.0 or less.

8 . The magnetic recording medium according to claim 1 , wherein
an average pore diameter of the entire magnetic recording medium measured in the state where the magnetic recording medium has been washed and dried is 6 nm or more and 11 nm or less.

9 . The magnetic recording medium according to claim 1 , wherein
a coercive force Hc of the magnetic layer in a longitudinal direction is 2000 Oe or less.

10 . The magnetic recording medium according to claim 1 , wherein
the magnetic layer includes 5 or more servo bands.

11 . The magnetic recording medium according to claim 10 , wherein
a ratio of the total area of the servo bands to the area of the surface is 4.0% or less.

12 . The magnetic recording medium according to claim 10 , wherein
a width of each of the servo bands is 95 μm or less.

13 . The magnetic recording medium according to claim 1 , wherein
the magnetic layer is configured to be capable of forming a plurality of data tracks, and a width of each of the data tracks is 2000 nm or less.

14 . The magnetic recording medium according to claim 1 , wherein
the magnetic layer is configured to be capable of recording data so that the minimum value of a magnetization reversal pitch L is 48 nm or less.

15 . The magnetic recording medium according to claim 1 , wherein
the average thickness of the substrate is 4.2 μm or less.

16 . The magnetic recording medium according to claim 1 , wherein
the lubricant contains at least one type selected from a fatty acid and a fatty acid ester, and the fatty acid contains a compound represented by the following general formula (1) or (2), and the fatty acid ester contains a compound represented by the following general formula (3) or (4).
CH 3 (CH 2 ) k COOH  (1)

(wherein k is an integer selected from a range of 14 or more and 22 or less in the general formula (1).)
CH 3 (CH 2 ) n CH═CH(CH 2 ) m COOH  (2)

(wherein a sum of n and m is an integer selected from a range of 12 or more and 20 or less in the general formula (2).)
CH 3 (CH 2 ) p COO(CH 2 ) q CH 3   (3)

(wherein p is an integer selected from a range of 14 or more and 22 or less and q is in integer selected from a range of 2 or more and 5 or less in the general formula (3).)
CH 3 (CH 2 ) r COO—(CH 2 ) s CH(CH 3 ) 2   (4)

(wherein r is an integer selected from a range of 14 or more and 22 or less and s is an integer selected from a range of 1 or more and 3 or less in the general formula (4).)

17 . The magnetic recording medium according to claim 1 , wherein
the magnetic layer contains a magnetic powder, and the magnetic powder includes hexagonal ferrite, ε-iron oxide, or Co-containing spinel ferrite.

18 . The magnetic recording medium according to claim 17 , wherein
the hexagonal ferrite contains at least one type of Ba or Sr, and the ε-iron oxide contains at least one type of Al or Ga.

19 . A cartridge, comprising:
the magnetic recording medium according to claim 1 ; and a storage unit that has a region to which adjustment information for adjusting tension to be applied in a longitudinal direction of the magnetic recording medium is written.

20 . The cartridge according to claim 19 , wherein
a communication unit that communicates with a recording/reproduction apparatus; and a control unit that
stores, in the region, the adjustment information received from the recording/reproduction apparatus via the communication unit, and
reads the adjustment information from the region and transmits the adjustment information to the recording/reproduction apparatus via the communication unit in response to a request from the recording/reproduction apparatus.

Assignees

• Sony Corp

Inventors

• Sekiguchi Noboru
• Yamaga Minoru

Classifications

• G11B23/037

  Single reels or spools · CPC title

• G11B5/78

  Tape carriers · CPC title

• G11B5/714 Primary

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/70678

  Ferrites · CPC title

• G11B5/00817 Primary

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title