公开(公告)号：JPH08255339A

公开(公告)日：1996-10-01

申请号：JP5915495

申请日：1995-03-17

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/714 ,  C09D5/23 ,  G11B5/716

Abstract: PURPOSE: To provide a magnetic recording medium excellent in surface smoothness, output characteristics and overwriting characteristics by forming plural magnetic layers on a substrate and imparting prescribed characteristics to each of the 1st and 2nd magnetic layers. CONSTITUTION: This magnetic recording medium 1 has a substrate 2 and plural magnetic layers 3 formed on the substrate 2. The magnetic layers 3 are a 1st magnetic layer 3a as the top layer and a 2nd magnetic layer 3b adjacent to the top layer. A back coating layer 4 is disposed if necessary. The 2nd magnetic layer 3b contains magnetic FeOx (4/3

公开(公告)号：JPH08249644A

公开(公告)日：1996-09-27

申请号：JP4675795

申请日：1995-03-07

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/73 ,  G11B5/735 ,  G11B5/704

Abstract: PURPOSE: To obtain a magnetic recording medium which allows of high-density recording, prevents jamming of a head due to whittling of a magnetic layer and is excellent in running durability. CONSTITUTION: A magnetic recording medium having a non-magnetic base, a magnetic layer provided on the surface side of the non-magnetic base and a back coat layer provided on the back of the non-magnetic base. This back coat layer is formed by applying a back coat material having magnetic powder on the back of the non-magnetic base.

公开(公告)号：JPH08203065A

公开(公告)日：1996-08-09

申请号：JP1457695

申请日：1995-01-31

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/706 ,  C09D5/23 ,  C09D7/12 ,  G11B5/712 ,  G11B5/716

Abstract: PURPOSE: To produce a magnetic recording medium good in surface smoothness, excellent in output (C/N) characteristic and overwrite characteristic and hardly causing a deterioration of durability resulted from v charge of the magnetic recording medium. CONSTITUTION: The medium has a non-magnetic supporting body and plural magnetic layers provided on the non-magnetic supporting body, and in these plural magnetic layers, a magnetic recording medium containing the first magnetic layer provided as an uppermost layer and the second magnetic layer provided adjacent to the first magnetic layer is provided. A soft magnetic powder and a conductive powder are incorporated in this second magnetic layer, and the conductive powder is more than one kind YBCO powder expressed by a general formula (I). YBa2 Cu3 O7-x ... (I). (0.03

公开(公告)号：JPH08180377A

公开(公告)日：1996-07-12

申请号：JP32549994

申请日：1994-12-27

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/716 ,  C09D5/23 ,  C09D7/12 ,  G11B5/738

Abstract: PURPOSE: To obtain a magnetic recording medium having both satisfactory high- and low-frequency characteristics and excellent also in overwriting characteristics. CONSTITUTION: In the magnetic recording medium 1 with a nonmagnetic substrate 2 and plural magnetic layers 3 disposed on the substrate 2 and including a 1st magnetic layer 3a as the top layer and a 2nd magnetic layer 3b adjacent to the 1st magnetic layer 3a, ferromagnetic metal powder having 140-160emu/g saturation magnetization is incorporated into the 1st magnetic layer 3a and soft magnetic powder into the 2nd magnetic layer 3b.

公开(公告)号：JPH08180372A

公开(公告)日：1996-07-12

申请号：JP32274394

申请日：1994-12-26

Applicant: KAO CORP

Inventor： NAKAYAMA HIDEHIKO ,  ISHIKAWA AKIRA ,  YAMASHITA KAZUTAKA

IPC: G11B5/71 ,  C09D5/23 ,  G11B5/716

Abstract: PURPOSE: To obtain a magnetic recording medium capable of a high density recording and excellent in durability by disposing a magnetic layer contg. a specified cyclic acetal as the layer adjacent to a magnetic layer disposed as the top layer of a magnetic recording medium. CONSTITUTION: This magnetic recording medium 1 has plural magnetic layers 3 disposed on the substrate 2 and the magnetic layers 3 are a 1st magnetic layer 3a as the top layer and a 2nd magnetic layer 3b adjacent to the 1st magnetic layer 3a. A back coating layer 4 is disposed on the rear side of the substrate if necessary. The 2nd magnetic layer 3b contains a cyclic acetal represented by formula I or II. In the formulae I, II, R is H or 1-21C straight chain or branched alkyl, R is 3C branched alkyl or 4-21C straight chain or branched alkyl when R is H, and R is 2-21C straight chain or branched alkyl when R is 1-21C straight chain or branched alkyl.

公开(公告)号：JPH08129745A

公开(公告)日：1996-05-21

申请号：JP26971294

申请日：1994-11-02

Applicant: KAO CORP

Inventor： YAMASHITA KAZUTAKA ,  NAKAYAMA HIDEHIKO ,  ISHIKAWA AKIRA

IPC: C09D5/23 ,  G11B5/708 ,  G11B5/71

Abstract: PURPOSE: To obtain a magnetic recording medium capable of satisfying high output required in recent years, not reducing output because of satisfactory surface properties and the hardly plasticizable surface and excellent in durability. CONSTITUTION: The top of a substrate is coated with a magnetic coating material contg. a binder and magnetic powder to obtain the objective magnetic recording medium. The magnetic coating material contains a reactional product of trifluoropropene oxide with a monoamine having a carboxylic acid group by 0.01-2.0 pts.wt. per 100 pts.wt. of the magnetic powder.

公开(公告)号：JPH0887739A

公开(公告)日：1996-04-02

申请号：JP22303494

申请日：1994-09-19

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/718 ,  C09D5/23 ,  C09D7/12 ,  G11B5/73 ,  G11B5/704

Abstract: PURPOSE: To provide a magnetic recording medium capable of high density recording and excellent especially in output characteristics and durability. CONSTITUTION: This magnetic recording medium consists essentially of a magnetic substrate 1, a nonmagnetic layer 2 formed on the substrate 1 and a magnetic layer 3 formed on the nonmagnetic layer 2. The magnetic layer 3 has many pores, the distribution of pore diameter has the peak at 5-20nm and the volume of pores whose diameter is within the range from 0.5×(peak diameter) to 1.5×(peak diameter) is >=80% of the total pore volume.

公开(公告)号：JPH0729155A

公开(公告)日：1995-01-31

申请号：JP17440693

申请日：1993-07-14

Applicant: KAO CORP

Inventor： SASAKI KENJI ,  YAMASHITA KAZUTAKA ,  KOBAYASHI HIDEYUKI

IPC: G11B5/716 ,  C09D5/23 ,  G11B5/73

Abstract: PURPOSE:To improve electromagnetic conversion characteristics such as S/N, corrosion-resistant properties, travelling performance, etc., by a method wherein a magnetic layer is composed of two layers and the first layer contains cobalt- coated iron oxide and the second layer contains cobalt-coated iron oxide whose coercive force is not less than a required value. CONSTITUTION:A first magnetic layer which is made of cobalt-coated iron oxide and binder and a second magnetic layer which is formed on the first magnetic layer and is made of cobalt-coated iron oxide having a coercive force not less than 1300Oe are provided. Magnetic coating material whose main component is cobalt-coated iron oxide having a coercive force about 500-1000Oe is applied to the substrate to form a first magnetic layer whose thickness is 0.3-5mum. The second magnetic layer is made of cobalt-coated iron oxide which is produced by an ordinary cobalt-coating method with needle-shaped iron oxide cores and has a coercive force not less than 1300Oe, preferably 1300-2000Oe.

公开(公告)号：JPH04106718A

公开(公告)日：1992-04-08

申请号：JP22587290

申请日：1990-08-28

Applicant: KAO CORP

Inventor： ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/702 ,  C09D5/23 ,  C09D127/04 ,  C09D127/06 ,  C09D175/00 ,  C09D175/04 ,  C10M105/34 ,  C10N40/18 ,  G11B5/708

Abstract: PURPOSE:To improve dispersibility of a magnetic powder and durability by using a polyurethane resin having a metal sulfonate group and a polyvinyl chloride resin as a binder and using a specified ester compd. as a lubricant. CONSTITUTION:A polyurethane resin having a metal sulfonate group and a polyvinyl chloride resin are used as a binder, and an ester compd. expressed by formula I is used as a lubricant. In the formula, R1 and R2 are satd. alkyl groups of 1-25 carbon number (with the sum of carbon number of R1 and R2 being 22-34) having a straight or branched chain, and R3 is a satd. or unsatd. alkyl group of 7-29 carbon number having a straight or branched chain. Namely, a magnetic coating material is prepared by adding a polyisocyanate compd. as a hardening agent to a mixture of metal powder, polyurethane resin, polyvinyl chloride resin, carbon black, chromium oxide, lubricant, methylethylketone, and cyclohexane, and mixing these materials. This coating material is applied on a polyethyeleneterephthalate film and subjected to nonorientation treatment, drying, mirror finishing, etc. Thus, dispersibility of the magnetic powder and durability are improved.

公开(公告)号：JPH03245318A

公开(公告)日：1991-10-31

申请号：JP4198690

申请日：1990-02-22

Applicant: KAO CORP

Inventor： NAKAYAMA HIDEHIKO ,  YAMASHITA KAZUTAKA

IPC: G11B5/708 ,  C09D5/23 ,  C09D167/00 ,  G11B5/73

Abstract: PURPOSE:To from a uniform, smooth magnetic layer and to improve recording/ reproducing characteristics by incorporating a low mol.wt. polyol and a polyester resin having metal sulfonate groups and amino groups into the magnetic layer. CONSTITUTION:A low mol.wt. polyol and a polyester resin having metal sulfonate groups and amino groups are incorporated into the magnetic layer. The use amt. of this polyester resin is about 0.1 - 50 pts.wt., preferably about 1 - 30 pts.wt. to 100 pts.wt. of the magnetic powder. It is preferable that the amino group in this polyester resin couple with carbon atoms which constitutes the main chain of the polyester resin. The amt. of low mol.wt. polyol is 0.1 - 20 pts.wt. and preferably 0.1 - 10 pts.wt. to the magnetic layer. Thereby, the obtd. magnetic layer is uniform and smooth, and the recording/reproducing characteristics can be improved.