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    MAGNETIC RECORDING MEDIUM AND PRODUCTION THEREOF
    141.
    发明专利
    MAGNETIC RECORDING MEDIUM AND PRODUCTION THEREOF 失效

    公开(公告)号：JPH07296365A

    公开(公告)日：1995-11-10

    申请号：JP9124694

    申请日：1994-04-28

    Applicant: KAO CORP

    Inventor： YAMASHITA KAZUTAKA ,  ISHIKAWA AKIRA ,  NAKAYAMA HIDEHIKO

    IPC: G11B5/716 ,  C09D5/23 ,  C09D7/12 ,  G11B5/73 ,  G11B5/738 ,  G11B5/704

    Abstract: PURPOSE:To obtain a magnetic recording medium excellent in the electrode conversion characteristics by providing a magnetic support, a nonmagnetic layer formed thereon, and a magnetic layer formed on the nonmagnetic layer. CONSTITUTION:In the magnetic recording medium, a magnetic layer has a thickness d2 (after a magnetic paint is applied and dried) in the range of 0.05-1.5mum, preferably in the range of 0.05-1.2mum and more preferably in the range of 0.1-1mum. A nonmagnetic layer has a thickness d1 (after a nonmagnetic paint is applied and dried) in the range of 0.5-4mum, preferable in the range of 0.5-3.5mum and more preferable in the range of 0.5-3mum, and a magnetic body has a thickness d. in the range of 1-10mm, preferably in the range of 1-100mum, wherein a relationship d0>d2 is preferably satisfied.

    MAGNETIC RECORDING MEDIUM
    142.
    发明专利
    MAGNETIC RECORDING MEDIUM 失效

    公开(公告)号：JPH07129947A

    公开(公告)日：1995-05-19

    申请号：JP27207293

    申请日：1993-10-29

    Applicant: KAO CORP

    Inventor： ISHIKAWA AKIRA ,  YAMASHITA KAZUTAKA ,  OTSUKA KAZUTOSHI

    IPC: C09D5/23 ,  G11B5/73 ,  G11B5/738 ,  G11B5/704

    Abstract: PURPOSE:To enable high density recording as well as to keep the interface between a thinned magnetic layer and an intermediate layer in a stable state by forming the magnetic layer on the intermediate layer contg. spindle-shaped alpha-iron oxide by a simultaneous coating system. CONSTITUTION:In a magnetic recording medium with a substrate, an intermediate layer formed on the substrate and a magnetic layer formed on the intermediate layer, the layers are formed by a simultaneous coating system. The intermediate layer consists of spindle-shaped alpha-iron oxide having =1,700Oe, preferably 1,700-2,000Oe coercive force and a binder or acicular cobalt stuck iron oxide having =1,600Oe, preferably 1,600-2,000Oe coercive force and a binder.

    MAGNETIC RECORDING MEDIUM
    143.
    发明专利
    MAGNETIC RECORDING MEDIUM 失效

    公开(公告)号：JPH0729160A

    公开(公告)日：1995-01-31

    申请号：JP17686793

    申请日：1993-07-16

    Applicant: KAO CORP

    Inventor： ISHIKAWA AKIRA ,  YAMASHITA KAZUTAKA ,  KOBAYASHI HIDEYUKI

    IPC: G11B5/706 ,  C09D5/23 ,  G11B5/716 ,  G11B5/73

    Abstract: PURPOSE:To improve both the durability and the recording/reproducing characteristics of a magnetic recording medium by a method wherein an intermediate layer made of fine magnetite powder having a low coercive force is formed on a substrate and a magnetic layer whose thickness is not larger than a specified value is formed on the intermediate layer. CONSTITUTION:A magnetic recording medium is composed of a substrate, an intermediate layer which is formed on a substrate and is made of magnetite powder which has an average particle diameter not larger than 0.2mum and a coercive force not larger than 150Oe and a binder and a magnetic layer which is formed on the intermediate layer and has a thickness not larger than 1mum. The magnetic layer is made of one of needle-shaped metal powder, needle-shaped cobalt-coated iron oxide powder and hexagomal ferromagnetic powder and binder. If the average particle diameter of the magnetite powder of the intermediate layer exceeds 0.2mum, the surface performance of the magnetic layer formed on the intermediate layer is deteriorated. If the coercive force of the magnetite powder exceeds 150Oe, the recording/ reproduction characteristics of the magnetic layer is hindered and, especially radio frequency characteristics are degraded.

    METHOD FOR MEASURING ROUGHNESS OF FILM SURFACE
    144.
    发明专利
    METHOD FOR MEASURING ROUGHNESS OF FILM SURFACE 失效

    公开(公告)号：JPH04148820A

    公开(公告)日：1992-05-21

    申请号：JP27239190

    申请日：1990-10-12

    Applicant: KAO CORP

    Inventor： YAMASHITA KAZUTAKA ,  UEDA YUKIHIRO

    IPC: G01B21/30

    Abstract: PURPOSE:To obtain the highly reliable measured result with excellent reproducibility by fixing a film on a substrate through a resin layer comprising resin or resin composition having a specified viscosity. CONSTITUTION:Resin or resin composition having the viscosity of 10 - 3,000 centipoises at 25 deg.C is applied on a glass substrate 11, and a resin layer 12 is formed. Thereafter, a film 13 is mounted, and the resin layer 12 is hardened. Thus the film 13 is fixed on the substrate 11. Therefore, the irregularites of the lower surface of the film is absorbed with the resin layer 12 before the hardening, and then the film 13 can be fixed. Even if there are irregularities on the lower surface of the film, the roughness does not affect the upper surface side of the film during the measurement. There is no bubble between the substrate 11 and the film 13. As a result, the waving and deviation of the film during the measurement can be avoided.

    MAGNETIC RECORDING MEDIUM
    145.
    发明专利
    MAGNETIC RECORDING MEDIUM 失效

    公开(公告)号：JPS6464117A

    公开(公告)日：1989-03-10

    申请号：JP22146587

    申请日：1987-09-04

    Applicant: KAO CORP

    Inventor： YAMASHITA KAZUTAKA ,  HIRAYAMA NAOKO

    IPC: G11B5/708 ,  C09D5/23 ,  C09D7/12 ,  C10M105/38 ,  C10N40/18

    Abstract: PURPOSE:To uniformly disperse the metal powder into a magnetic layer by incorporating specific ester into the magnetic layer. CONSTITUTION:Metal powder is uniformly dispersed into the binder of the magnetic layer provided on a nonmagnetic base and the surface smoothness and electromagnetic conversion characteristics thereof are enhanced if at least one kind of the monoester, diester or triester of the pentraerythritol expressed by the formula I is incorporated into the magnetic layer. In the formula, R1, R2, R3: H or acyl group of 3-23C; R1, R2, R3 are not H simultaneously.

    BINDER FOR MAGNETIC RECODING MEDIUM
    146.
    发明专利
    BINDER FOR MAGNETIC RECODING MEDIUM 失效

    公开(公告)号：JPS62248127A

    公开(公告)日：1987-10-29

    申请号：JP9153786

    申请日：1986-04-21

    Applicant: KAO CORP

    Inventor： OKADA TOMOYUKI ,  KANNEN NAOKI ,  YAMASHITA KAZUTAKA ,  ISHIKAWA AKIRA ,  TSUSHIMA RIKIO

    IPC: G11B5/702 ,  C09D5/23 ,  C09D175/00 ,  C09D175/04 ,  C09D175/06

    Abstract: PURPOSE:To obtain high durability in a wide environment in the temp. range of low to high temp. by using thermoplastic polyurethane resin whose mol. wt., tensile rupture strength, tensile rupture elongation, 100% modulus and glass transition temp. have been specified. CONSTITUTION:Thermoplastic polyurethane resin is used as a binder for a magnetic recording medium. the polyurethane resin has 5,000-40,000 number average mol. wt. analyzed by gel permeation chromatography, >=200kg/cm rupture strength, 100-400% rupture elongation and >=150kg/cm 100% modulus measured by a tension test at 100mm/min tension speed, and >=40 deg.C glass transition temp. determined by the measurement o the dynamic viscoelasticity. Thus, high durability can be provided in a wise environment in the temp. range of low to high temp.

    MAGNETIC RECORDING MEDIUM AND BINDER THEREFOR
    147.
    发明专利
    MAGNETIC RECORDING MEDIUM AND BINDER THEREFOR 失效

    公开(公告)号：JPS62165726A

    公开(公告)日：1987-07-22

    申请号：JP748286

    申请日：1986-01-17

    Applicant: KAO CORP

    Inventor： KANNEN NAOMI ,  TSUSHIMA RIKIO ,  YAMASHITA KAZUTAKA ,  OKADA TOMOYUKI

    IPC: G11B5/702 ,  C09D5/23 ,  C09D175/00 ,  C09D175/04

    Abstract: PURPOSE:To improve the dispersibility of magnetic particles while maintaining the mechanical characteristics which a specific polyurethane resin resin possesses by using said polyurethane resin as a binder for a magnetic recording medium. CONSTITUTION:The polyurethane resin which is produced from the polyketone compd. having at least two hydroxyl groups and expressed by formula I or II as a polyol component is used as the binder for the magnetic recording medium. In formula, n is 1-43 number and m is 1-53 number. The polyketone compd. has preferably 400-6000 number average mol. wt. and more particularly preferably 500-4004000 number average mol. wt. in terms of the flexibility and strong toughness of the resultant polyurethane resin. The number average mol. wt. of the polyurethane resin is 1000-100000, more preferably 5000-50000. The magnetic recording medium is obtd. by providing a magnetic layer formed by dispersing pulverized ferromagnetic powder in such binder on a nonmagnetic base. The specific surface area of the pulverized ferromagnetic powder is preferably /g.

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