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公开(公告)号：JPH08180380A
公开(公告)日：1996-07-12
申请号：JP32885794
申请日：1994-12-28
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA , SHIMIZU SATOSHI
Abstract: PURPOSE: To obtain a magnetic recording medium excellent in output (C/N) characteristics, especially both low- and high-frequency output 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, the difference between the coercive force of the 1st magnetic layer 3a and that of the 2nd magnetic layer 3b is regulated to -200 to +200Oe and the ratio (Br2 /Br1 ) of the residual magnetic flux density Br2 of the 2nd magnetic layer 3b to the residual magnetic flux density Br1 of the 1st magnetic layer 3a is regulated to 0.2-0.9. The thickness of the 1st magnetic layer 3a is regulated to 0.05-1.0μm and the 1st magnetic layer 3a is formed by coating while the 2nd magnetic layer is in a wet state.
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公开(公告)号：JPH08180378A
公开(公告)日：1996-07-12
申请号：JP32636694
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 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, soft magnetic powder is incorporated into the 2nd magnetic layer 3b. The soft magnetic powder satisfies the relation of 0.05 and standard deviation ΔL of major axis size L in its plane projected image and the relation of 0.05 and standard deviation ΔW of minor axis size W.
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公开(公告)号：JPH0845065A
公开(公告)日：1996-02-16
申请号：JP18028494
申请日：1994-08-01
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE:To obtain a medium capable of high density recording and excellent in output characteristics by incorporating a compd. represented by a specified formula into a magnetic substrate. CONSTITUTION:A magnetic recording medium is composed of a magnetic substrate, a nonmagnetic layer and a magnetic layer, and a back coating layer is further disposed if necessary. At this time, one of two kinds of compds. represented by formulae I, II is incorporated into the magnetic substrate. The compds. are components for chiefly reducing the viscosity of a thermoplastic resin. Since the stiffness of the resultant magnetic recording medium is improved and the medium is made tough, the electromagnetic transducing characteristics of the medium are improved.
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公开(公告)号：JPH0817045A
公开(公告)日：1996-01-19
申请号：JP14835694
申请日：1994-06-29
Applicant: KAO CORP
Inventor： ISHIKAWA AKIRA , NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE:To obtain a magnetic recording medium capable of high density recording and excellent in output characteristics especially in a high frequency band. 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 coercive force Hc of the magnetic substrate 1 is 1,700-5,000Oe, the coercive force Hc' of the magnetic layer 3 is 1,500-2,500Oe and the coercive force Hc is higher than the coercive force Hc'.
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公开(公告)号：JPH0817044A
公开(公告)日：1996-01-19
申请号：JP14835594
申请日：1994-06-29
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 output characteristics over the region from a low frequency band to a high frequency band. 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 coercive force Hc of the magnetic substrate 1 is 400-1,500Oe, the coercive force Hc' of the magnetic layer 3 is 700-2,500Oe and the ratio of Hc' to Hc (Hc'/Hc) is >=1.5.
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Patent Agency Ranking
公开(公告)号：JPH06243459A
公开(公告)日：1994-09-02
申请号：JP2544093
申请日：1993-02-15
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA
Abstract: PURPOSE:To produce a satisfactory lubricating effect even at low temp., to ensure retentivity of lubricating action, to suppress blooming phenomenon at low temp. and to prevent the reduction of output by using fatty acid ester represented by a specified formula as a lubricant for a magnetic coating film. CONSTITUTION:Fatty acid ester represented by formula I is used as a lubricant for a magnetic coating film. In the formula, a part represented by formula II is a residue of polyalcohol having 2-5 hydroxyl groups, R2 is a group represented by formula III, (m) is 1-5 and R3 is 10-24C hydrocarbon. A satisfactory lubricating effect is produced even in an environment at low temp. and the reduction of output is not caused because retentivity of lubricating action is ensured and blooming phenomenon can be suppressed at low temp.
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公开(公告)号：JPH04209664A
公开(公告)日：1992-07-31
申请号：JP40017790
申请日：1990-12-03
Applicant: KAO CORP
Inventor： NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
Abstract: PURPOSE:To prepare the title material having an increased solid content and an improved degree of dispersion in a short time by a simple process by mixing a compsn. having a specified solid content in the first mixing step, increasing the solid content in a drying step, and mixing further in the second mixing step. CONSTITUTION:A process for preparing a magnetic coating material by mixing a compsn. mainly comprising a magnetic powder, a binder, and a solvent on a twin-shaft continuous mixer, wherein the mixer is one having screws 5 and paddles 6 on the shafts 3 and 4 and the compsn. having a specified solid content is mixed in the first mixing step (region (b)). Then, the compsn. is transferred to a drying step (region (c)) where a part of the solvent is removed to increase the solid content to another specified value. Finally, the compsn. having the increased solid content is mixed further in the second mixing step (region (d) and region (f)).
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公开(公告)号：JPH03288323A
公开(公告)日：1991-12-18
申请号：JP9120590
申请日：1990-04-04
Applicant: KAO CORP
Inventor： NAKAYAMA HIDEHIKO , YAMASHITA KAZUTAKA
IPC: C08G18/42 , C08G18/46 , C09D5/23 , C09D175/00 , C09D175/04 , G11B5/702
Abstract: PURPOSE:To obtain the magnetic recording medium having excellent durability by incorporating the polyurethane resin obtd. by bringing specific polymethyl valerolactonediol and polyisocyanate into reaction. CONSTITUTION:The polyurethane resin obtd. by bringing the polymethyl valerolactone dial obtd. by polymerizing beta-methyl-delta-valerolactone with a dihydroxy compd. having the metal base of sulfonic acid as a polymn. initiator and the polyisocyanate into reaction is incorporated into the magnetic layer of the magnetic recording medium. The viscosity of the polyurethane resin lowers and the handling property improves. The reason thereof lies in that the polyester of the beta-methyl-delta-valerolactone is much lower in viscosity than the polyester of the epsilon-caprolactone. The magnetic recording medium having the extremely high dispersibility of the magnetic powder, the excellent smoothness of the surface of the magnetic coating film and the excellent wet heat resistance and durability is obtd. in this way.
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公开(公告)号：JPH01149220A
公开(公告)日：1989-06-12
申请号：JP30640087
申请日：1987-12-03
Applicant: KAO CORP
Inventor： YAMASHITA KAZUTAKA , HIRAYAMA NAOKO
Abstract: PURPOSE:To improve the dispersibility of ferromagnetic powder by incorporating specific phosphate and silane coupling agent into a magnetic layer. CONSTITUTION:The phosphate expressed by formula I and the silane coupling agent expressed by formula II are incorporated into the magnetic layer. In formula I, R1 denotes an aliphat. hydrocarbon group of 1-24C; A denotes an alkylene group of 2-4C; (n) denotes 0 or integer in the range of 1-30 integer; (m) denotes 1, 1.5 or 2. In formula II, R2 denotes an alkyl group of 1-4C; R3 denotes an aliphat. hydrocarbon group of 1-24C. Both the ratios of the phosphate and silane coupling agent to be used are preferably 0.5-8pts.wt., more preferably 1.5-7pts.wt. per 100pts.wt. ferromagnetic powder. The dispersibility of the ferromagnetic powder is thereby improved.
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公开(公告)号：JPS643986B2
公开(公告)日：1989-01-24
申请号：JP12841582
申请日：1982-07-23
Applicant: KAO CORP
Inventor： NAKASONE YUMIO , TANAKA YOSHIAKI , TAKEMOTO HIROTAKA , YAMASHITA KAZUTAKA
IPC: D06M15/00 , D06M15/327 , D06M15/333
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