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公开(公告)号：JPH1166538A
公开(公告)日：1999-03-09
申请号：JP21370597
申请日：1997-08-07
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To provide a magnetic recording medium of multi layers wherein an interface of upper and lower layers is formed uniformly, an upper magnetic layer has superior surface smoothness, and superior electromagnetic conversion characteristics, particularly, electromagnetic conversion characteristics at a high-frequency region are exerted. SOLUTION: A magnetic recording medium 1 has a supporting body, an intermediate layer 3 and a magnetic layer 4. The intermediate layer 3 and magnetic layer 4 are formed by a simultaneous multilayer coating method. For the intermediate layer 3, inorganic particles of an average adsorption water content per unit surface area of 0.12-2.0 mg/m which is defined by the formula are used. An arithmetic average roughness Ra of the magnetic layer is 0.0020-0.0070 μm.
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公开(公告)号：JPH10302245A
公开(公告)日：1998-11-13
申请号：JP11135897
申请日：1997-04-28
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA , NAKAYAMA HIDEHIKO , ISHIKAWA AKIRA
IPC: C10M105/54 , C09D5/23 , C10N40/18 , G11B5/70 , G11B5/738
Abstract: PROBLEM TO BE SOLVED: To provide a high density magnetic recording medium which has both the excellent electromagnetic conversion characteristics and the excellent running durability under a low temperature and a low humidity. SOLUTION: A recording medium has a supporter 2, a magnetic or nonmagnetic intermediate layer 3 formed on the supporter 2 and a magnetic layer 4 as an uppermost layer. The thicknesses of the intermediate layer 3 and the magnetic layer 4 is 0.3-3.0 μm and 0.1-0.5 μm respectively and the ratio of the thicknesses (former/latter) is 1/20-3/10. The magnetic layer contains ferromagnetic powder and carbon black. The ferromagnetic powder is needle-shaped metallic magnetic powder which contains aluminum in the powder surface layers and whose average long axes are 0.5-0.15 μm. The peak value of the fine hole diameter distribution of fine holes existing in the surface of the magnetic layer is 5.5-11 nm.
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公开(公告)号：JPH1055530A
公开(公告)日：1998-02-24
申请号：JP20972496
申请日：1996-08-08
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA , NAKAYAMA HIDEHIKO , ISHIKAWA AKIRA
IPC: C09D5/23 , C09D127/04 , C09D127/06 , C09D163/00 , C09D175/00 , C09D175/04 , G11B5/702 , G11B5/73 , G11B5/735
Abstract: PROBLEM TO BE SOLVED: To improve the characteristics of a magnetic coating material as a coating material, to reduce error rate and to improve durability as well as to increase output by using specified compds. as a binder and a curing agent in a magnetic layer. SOLUTION: The top layer of this magnetic recording medium is formed by coating the top of a middle layer 3 with a magnetic coating material contg. a binder having at least two epoxy groups in one molecule and a number average mol.wt. of 5,000-50,000, polyurethane resin having two or more carboxyl groups in one molecule and a number average mol.wt. of 500-30,000 as a curing agent and a promoter as well as magnetic powder, carbon powder (carbon black), inorg. particles having a Mohs hardness of >=8, fatty acid and fatty acid ester. The binder is made of vinyl chloride resin or consists of vinyl chloride resin and polyurethane resin.
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公开(公告)号：JPH09198650A
公开(公告)日：1997-07-31
申请号：JP606596
申请日：1996-01-17
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To improve the traveling property, output and light shieldability and to suppress the adhesion of dust by electrification by providing the rear surface side of a base provided with a magnetic layer on its front surface side with a back coating layer contg. magnetite powder having a specified plate diameter and plate shape ratio. SOLUTION: The front surface side of the base 2 is provided with an intermediate layer 5 and the magnetic layer 3 in this order and the rear surface side thereof is provided with the back coating layer 4 contg. the magnetite powder having the plate diameter of 0.05 to 2.0μm and the plate shape ratio of 3 to 40 and carbon black. The thickness of the layer 3 is specified to 0.05 to 1.0μm. Acicular ferromagnetic metallic powder having coercive force of 1500 to 2400 Oe or hexagonal ferrite powder having coercive force of 1300 to 2300 Oe is incorporated into the layer. The magnetic recording medium 1 composed of such base 2 and the layers 3 to 5 is improved in rigidity and is improved in the electrical conductivity of the layer 4 as well. As a result, the traveling property is improved, the output is enhanced and the light shieldability is enhanced, thereby, the control of the traveling system is improved and the adhesion of the dust by electrification is suppressed.
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公开(公告)号：JPH09180172A
公开(公告)日：1997-07-11
申请号：JP34303195
申请日：1995-12-28
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To obtain a magnetic recording medium excellent in output (C/N) characteristics in a high-frequency region, having high light shielding property, ensuring satisfactory control in a running system and less liable to the sticking of dust due to electrification because of imparted proper electric conductivity. SOLUTION: This recording medium 1 has a substrate 2 and plural magnetic layers 3 formed on the substrate 2. The magnetic layers 3 include a 1st magnetic layer 3a formed as the top layer and a 2nd magnetic layer 3b adjacent to the 1st magnetic layer 3b. The 1st magnetic layer 3a contains ferromagnetic metal powder and has 1,700-2,400Oe coercive force and 0.05-0.8μm thickness. The 2nd magnetic layer 3b contains acicular Mn-contg. nonmagnetic iron oxide powder and hexagonal ferrite powder or spinel type ferrite powder having
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Patent Agency Ranking
公开(公告)号：JPH0991675A
公开(公告)日：1997-04-04
申请号：JP24295395
申请日：1995-09-21
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA , ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO
IPC: C08G18/42 , C08G18/46 , C09D5/23 , C09D175/00 , C09D175/04 , G11B5/702
Abstract: PROBLEM TO BE SOLVED: To improve the dispersibility of magnetic powder by using polyurethane resin having nitro groups in each molecule as a resin binder forming a magnetic layer. SOLUTION: This magnetic recording medium has a substrate and a magnetic layer consisting essentially of magnetic powder and a resin binder formed on the substrate and polyurethane resin having nitro groups in each molecule is used as the resin binder. The polyurethane resin has been blocked with an oxime blocking agent and has nitro groups by 10-1,000 equiv. per 10 g polymer. The number of nitro groups per one molecule represented by number average mol.wt. (expressed in terms of plystyrene) in measurement by GPC is
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公开(公告)号：JPH0935246A
公开(公告)日：1997-02-07
申请号：JP18605095
申请日：1995-07-21
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To ensure superior electromagnetic transducing characteristics and to suppress the deterioration of the electromagnetic transducing characteristics with the lapse of time by specifying the amt. of a residual solvent in a back coating layer. SOLUTION: This magnetic recording medium 1 has a nonmagnetic substrate 2, a magnetic layer 4 disposed on the front side of the substrate 2, a middle layer 3 interposed between the substrate 2 and the magnetic layer 4 and a back coating layer 5 disposed on the rear side of the substrate 2. The amt. of a residual solvent in the back coating layer 5 has been regulated to 5-2,000ppm. The magnetic layer 4 contains ferromagnetic metal powder and has 1,800-2,400 Oe coercive force and 3,000-4,500G saturation magnetic flux density. When the magnetic layer 4 contains hexagonal ferrite powder, it has 1,500-2,200 Oe coercive force and 1,500-2,500G saturation magnetic flux density.
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公开(公告)号：JPH08180376A
公开(公告)日：1996-07-12
申请号：JP32549894
申请日：1994-12-27
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE: To obtain a magnetic recording medium having satisfactory surface smoothness and excellent in output (C/N) characteristics (high- and low-frequency characteristics) and 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, hexagonal ferrite powder having 400-700Oe coercive force is incorporated into the 2nd magnetic layer 3b.
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公开(公告)号：JPH08161729A
公开(公告)日：1996-06-21
申请号：JP29710794
申请日：1994-11-30
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE: To obtain a magnetic recording medium which makes high density possible and achieves excellence in output characteristic and durability by setting the ratio between the content of an epoxy group of a magnetic paint and the content of sulfur at 1-2. CONSTITUTION: A non-magnetic layer 2 is provided on a support body 1 and a magnetic layer 3 thereon. A back coated layer 4 is provided on the rear of the support body 1 as required. The magnetic layer 3 is made up of a magnetic paint having a polymer containing an epoxy group and/or sulfur as binder. The ratio between the content of the epoxy group and the content of the sulfur (content of epoxy group/content of sulfur) is set at 1-20. Thus, a magnetic recording medium makes high density possible, especially achieving excellence in output characteristic and durability.
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公开(公告)号：JPH0855332A
公开(公告)日：1996-02-27
申请号：JP18970194
申请日：1994-08-11
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE:To conduct high density recording by forming a second magnetic layer having specified coercive force and specified thickness on a first magnetic layer having high coercive force and not contributing to recording and reproducing. CONSTITUTION:On the one surface of a supporting body, a first magnetic layer 2 and a second magnetic layer 3 are formed in this order, and a back coating layer 4 is formed if necessary on the back surface of the supporting body 1 to obtain a magnetic tape. The thickness of the second magnetic layer 3 is specified to 0.05-1mum. The magnetic powder of the second magnetic layer 3 consists of ferromagnetic iron oxide comprising FeOx (1.33 =2500Oe, that the layer is not magnetized under operational conditions of the magnetic tape and does not contribute to recording and reproducing of video of audio signals.
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