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公开(公告)号：JPH11195218A
公开(公告)日：1999-07-21
申请号：JP36078697
申请日：1997-12-26
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA , TAKESHIGE YUICHI , NAKAYAMA HIDEHIKO
IPC: C09D5/23 , C09D127/06 , G11B5/702
Abstract: PROBLEM TO BE SOLVED: To provide a high-density magnetic recording medium having excellent electromagnetic conversion characteristics and durabllity. SOLUTION: A vinyl chloride copolymer is used as a binder for a recording medium. This copolymer is obtd. by the polymn. of a polymn. system containing vinyl monomers essentially comprising vinyl chloride, a polymn. initiator and a chain-transfer agent having a polar group at one molecular end selected from SO3 M, OH, NO2 , NH2 , PO4 MM' and SO4 M (wherein M and M' are each H, NH4 , Na and K).
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公开(公告)号：JPH11149630A
公开(公告)日：1999-06-02
申请号：JP31338297
申请日：1997-11-14
Applicant: KAO CORP
Inventor： KOBAYASHI HIDEYUKI , YAMASHITA KAZUTAKA , SATO MASAYASU
Abstract: PROBLEM TO BE SOLVED: To provide a magnetic recording medium with which such required characteristics as output improvement by a head touch, tape interchangeability prevention of occurrence of edge crack by bending rigidity and a decrease of a fluctuation in slit width, are improved by controlling rigidity, thereby enhancing the rigidity particularly in a transverse direction and a process for producing the same. SOLUTION: This magnetic recording medium is constituted by disposing >=1 layer of intermediate layer contg. at least nonmagnetic powder and binder on a base 1 and disposing a magnetic as an upper layer contg. at least ferromagnetic powder and a binder thereon. The nonmagnetic powder of the intermediate layer is acicular and the alignment coefft. (α) of the nonmagnetic powder to its longitudinal direction is 0 to 0.8.
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公开(公告)号：JPH11144223A
公开(公告)日：1999-05-28
申请号：JP30753397
申请日：1997-11-10
Applicant: KAO CORP
Inventor： ISHIKAWA JUNKO , YAMASHITA KAZUTAKA , KOBAYASHI HIDEYUKI
Abstract: PROBLEM TO BE SOLVED: To provide a magnetic recording medium excellent in traveling durability, electromagnetic conversion characteristics and corrosion resistance. SOLUTION: In this magnetic recording medium, an intermediate layer containing at least a magnetic powder and/or nonmagnetic powder and a binder is formed on a nonmagnetic supporting body, and a magnetic layer as the uppermost layer containing at least a ferromagnetic metal powder, a binder, lubricant, a hardening agent, carbon black and alumina is formed thereon. In this medium, the dry thickness of the magnetic layer is 0.05 to 0.35 μm, the ferromagnetic metal powder used is an acicular ferromagnetic metal powder having >=40 m /g BET specific surface area, and the binder contains a vinyl chloride copolymer and a polyurethane resin. By ESCA measurement of the surface of the magnetic layer, the integral intensity ratio (α) of C1-2p spectrum to C-1s spectrum is 0.02 to 0.6, the integral intensity ratio (β) of N-1s spectrum to C-1s spectrum is 0.01 to 0.4, the integral intensity ratio (γ) of Fe-2P3/2 spectrum to C-1s spectrum is 0.1 to 1.2. The distribution of pore diameter of pores present on the magnetic layer surface has a peak in 5 to 10 nm range.
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公开(公告)号：JPH10177713A
公开(公告)日：1998-06-30
申请号：JP31331097
申请日：1997-11-14
Applicant: KAO CORP
Inventor： KANNEN NAOKI , TSUSHIMA RIKIO , YAMASHITA KAZUTAKA , OKADA TOMOYUKI
IPC: C08L75/04 , C09D5/23 , C09D175/04 , G11B5/702
Abstract: PROBLEM TO BE SOLVED: To improve surface smoothness, dispersibility of a magnetic powder and durability while holding mechanical properties by using a polyurethane resin having one or more ammonium salts of COOH groups as a binder. SOLUTION: The number average mol.wt. of the polyurethane resin used is 5000 to 50000, and the compounding ratio of the polyurethane resin to a ferromagnetic fine powder is preferably by weight, 10 to 100 of the resin to 100 of the ferromagnetic fine powder. It is preferable that the ferromagnetic fine powder has /g specific surface area. As for the polyurethane resin, any polyurethane resin having isocyanate groups on both molecular ends, having hydroxyl groups on both molecular ends, or having one isocyanate group on one molecular end and a hydroxyl group on the other end can be used as far as the resin has the polar groups above described in the molecular chain. The polyurethane resin may contain one or more other polar groups as polar groups except for ammonium salt of COOH groups in the molecular chain.
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公开(公告)号：JPH1055528A
公开(公告)日：1998-02-24
申请号：JP20972296
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 , 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: A magnetic layer 4 is the top layer of this magnetic recording medium and 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 10,000-50,000, an ester compd. having two or more carboxyl groups in one molecule on average and a number average mol.wt. of 500-8,000 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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Patent Agency Ranking
公开(公告)号：JPH09147351A
公开(公告)日：1997-06-06
申请号：JP30796995
申请日：1995-11-27
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To improve electromagnetic transducing characteristics, to suppress the deterioration of the characteristics during storage and to improve shelf stability by specifying the thickness, center line surface roughness and residual solvent content of a magnetic layer. SOLUTION: This magnetic recording medium 1 has a nonmagnetic substrate 2, a middle layer 3 and a magnetic layer 4 or further has a back coating layer 5 formed on the rear side of the substrate 2 if necessary. The magnetic layer 4 has 0.05-0.6μm thickness, 2-10nm center line surface roughness and 5-3,000ppm residual solvent content, contains ferromagnetic metal powder and has 1,800-2,400 Oe coercive force and 3,000-4,500G saturation magnetic flux density.
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公开(公告)号：JPH09134522A
公开(公告)日：1997-05-20
申请号：JP29014195
申请日：1995-11-08
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PROBLEM TO BE SOLVED: To provide a recording medium displaying superior surface smoothness at a magnetic layer and having superior electromagnetic conversion properties in a high frequency region. SOLUTION: The recording medium is provided with a supporting body 2 and a magnetic layer 3 set on the supporting body 2. The magnetic layer 3 contains needle-shaped ferromagnetic metallic particles (a) of 0.05-0.14μm mean length and 1700-2300Oe coercive force or sheet-like hexagonal ferrite particles (c) of 0.01-0.07μm breadth and 1400-2200Oe coercive force, spherical or amorphous spinel-type ferrite particles (b) of 0.005-0.09μm average particle size and a coercive force of larger than 0 and smaller than 150Oe, and a binder. A compounding ratio (weight ratio) of the spinel-type ferrite particles (b) to the ferromagnetic metallic particles (a) or hexagonal ferrite particles (c) is 0.03-0.3.
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公开(公告)号：JPH08287452A
公开(公告)日：1996-11-01
申请号：JP8678695
申请日：1995-04-12
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE: To obtain a magnetic recording medium capable of high density recording and having superior durability by disposing plural magnetic layers on a substrate and incorporating at least one of compds. represented by prescribed formulae in the lst magnetic layer to be the uppermost layer of plural magnetic layers and the 2nd magnetic layer disposed adjoining to the 1st one. CONSTITUTION: This magnetic recording medium 1 has a substrate 2 and plural magnetic layers 3 disposed on the substrate 2. The magnetic layers 3 consists of a 1st magnetic layer 3a disposed as the uppermost layer and a 2nd magnetic layer 3b disposed adjoining to the 1st magnetic layer 3a. A back coating layer 4 is disposed on the rear side of the substrate 2 if necessary. The 2nd magnetic layer 3b contains at least one of compds. represented by formulae I, II, wherein R is 1-26C straight chain or branched satd. or unsatd. hydrocarbon. This magnetic recording medium enables high density recording and is excellent in durability. Even when high density recording is attained while reducing the thickness of the lst magnetic layer 3a, high durability is ensured.
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公开(公告)号：JPH08287451A
公开(公告)日：1996-11-01
申请号：JP9341795
申请日：1995-04-19
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
IPC: C10M105/32 , C09D5/23 , C10M105/68 , C10N40/18 , G11B5/71
Abstract: PURPOSE: To obtain a magnetic recording medium capable of high density recording and excellent in durability by disposing plural magnetic layers on a substrate and incorporating at least one of compds. represented by prescribed formulae in the lst magnetic layer to be the upper most layer and the 2nd magnetic layer disposed adjoining to the 1st one. CONSTITUTION: This magnetic recording medium 1 has a substrate 2 and plural magnetic layers 3 disposed on the substrate 2. The magnetic layers 3 consists of a 1st magnetic layer 3a disposed as the top layer and a 2nd magnetic layer 3b disposed adjoining to the 1st magnetic layer 3a. A back coating layer 4 is disposed on the rear side of the substrate 2 if necessary. The 2nd magnetic layer 3b contains compd. represented by general formula A and at least one kind of adamantane deriv. selected from among compds. represented by general formulae B-F. In the formulae A-D, each of R and R' is 1-26C straight chain or branched aliphatic or alicyclic hydrocarbon.
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公开(公告)号：JPH08180381A
公开(公告)日：1996-07-12
申请号：JP32885894
申请日：1994-12-28
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 and overwriting characteristics. CONSTITUTION: In this 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, the 2nd magnetic layer 3b contains soft magnetic oxide powder adjusted to 200-300Å crystallite size.
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