U.S. patent application number 11/453978 was filed with the patent office on 2006-12-28 for manufacturing method of tape-form recording medium.
This patent application is currently assigned to FUJI PHOTO FILM CO., LTD.. Invention is credited to Yutaka Kakuishi, Katsuhiko Meguro, Katsumi Ryoke.
Application Number | 20060289335 11/453978 |
Document ID | / |
Family ID | 36950486 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060289335 |
Kind Code |
A1 |
Kakuishi; Yutaka ; et
al. |
December 28, 2006 |
Manufacturing method of tape-form recording medium
Abstract
A manufacturing method of a tape-form recoding medium in the
present invention includes a raw web manufacturing process of
forming a data recoding layer on one side of a substrate and a back
coat layer having a minute convexity on the other side thereof, and
thus manufacturing raw web of the tape-form recoding medium; a raw
web winding process of winding the raw web with a predetermined
tension; a raw web rewinding process of rewinding the raw web; and
a raw web heating process of heating the rewound raw web.
Inventors: |
Kakuishi; Yutaka; (Kanagawa,
JP) ; Ryoke; Katsumi; (Kanagawa, JP) ; Meguro;
Katsuhiko; (Kanagawa, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
FUJI PHOTO FILM CO., LTD.
|
Family ID: |
36950486 |
Appl. No.: |
11/453978 |
Filed: |
June 16, 2006 |
Current U.S.
Class: |
206/752 ;
G9B/5.295 |
Current CPC
Class: |
G11B 5/84 20130101 |
Class at
Publication: |
206/752 |
International
Class: |
B65D 79/00 20060101
B65D079/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2005 |
JP |
2005-182448 |
Claims
1. A manufacturing method of a tape-form recoding medium
comprising: a raw web manufacturing process of forming a data
recoding layer on one side of a substrate and a back coat layer
having a minute convexity on the other side thereof, and
manufacturing raw web of the tape-form recoding medium; a raw web
winding process of winding the raw web with a predetermined
tension; a raw web rewinding process of rewinding the raw web; and
a raw web heating process of heating the raw web rewound.
2. The manufacturing method of the tape-form recoding medium
according to claim 1 further comprising a strain relief process of
heating the raw web wound and relieving a strain of the raw web
after the raw web winding process and before the raw web rewinding
process.
3. The manufacturing method of the tape-form recoding medium
according to claim 1 further comprising a raw web slitting process
of slitting the raw web after the raw web winding process and
before the raw web rewinding process, wherein the raw web rewinding
process winds the slit raw web.
4. The manufacturing method of the tape-form recoding medium
according to claim 2 further comprising a raw web slitting process
of slitting the raw web after the strain relief process and before
the raw web rewinding process, wherein the raw web rewinding
process winds the slit raw web.
5. The manufacturing method of the tape-form recoding medium
according to claim 1, wherein the raw web is rewound on a hub
having a taper on a tape winding face in the raw web rewinding
process.
6. The manufacturing method of the tape-form recoding medium
according to claim 2, wherein the raw web is rewound on a hub
having a taper on a tape winding face in the raw web rewinding
process.
7. The manufacturing method of the tape-form recoding medium
according to claim 3, wherein the raw web is rewound on a hub
having a taper on a tape winding face in the raw web rewinding
process.
8. The manufacturing method of the tape-form recoding medium
according to claim 4, wherein the raw web is rewound on a hub
having a taper on a tape winding face in the raw web rewinding
process.
9. The manufacturing method of the tape-form recoding medium
according to claim 1, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
10. The manufacturing method of the tape-form recoding medium
according to claim 2, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
11. The manufacturing method of the tape-form recoding medium
according to claim 3, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
12. The manufacturing method of the tape-form recoding medium
according to claim 4, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
13. The manufacturing method of the tape-form recoding medium
according to claim 5, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
14. The manufacturing method of the tape-form recoding medium
according to claim 6, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
15. The manufacturing method of the tape-form recoding medium
according to claim 7, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
16. The manufacturing method of the tape-form recoding medium
according to claim 8, wherein the data recording layer is a
magnetic layer and 1 to 150 nm in thickness.
17. The manufacturing method of the tape-form recoding medium
according to claim 5, wherein one side length of the raw web out of
both sides in width directions thereof is formed longer than the
other side length.
18. The manufacturing method of the tape-form recoding medium
according to claim 6, wherein one side length of the raw web out of
both sides in width directions thereof is formed longer than the
other side length.
19. The manufacturing method of the tape-form recoding medium
according to claim 7, wherein one side length of the tape-form
recoding medium obtained in the raw web heating process is formed
longer than the other side length out of both sides in width
directions of the medium.
20. The manufacturing method of the tape-form recoding medium
according to claim 8, wherein one side length of the tape-form
recoding medium obtained in the raw web heating process is formed
longer than the other side length out of both sides in width
directions of the medium.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a manufacturing method of a
tape-form recoding medium.
[0003] 2. Description of the Related Art
[0004] As a conventional manufacturing method of a magnetic tape is
known a method of: manufacturing a magnetic tape bulk roll by
coating a coating liquid for forming a magnetic layer containing a
magnetic material, a bonding agent, and a solvent on one side of a
magnetic tape substrate sent out from a magnetic tape substrate
bulk roll, and then orienting, drying, and winding the raw web;
slitting a peripheral face of the magnetic tape bulk roll from one
edge to the other edge for every tape width; and winding the
magnetic tape from the slit raw web for every cassette tape, using
a tape winder (for example, see paragraphs 0022 to 0024 in Japanese
Patent Laid-Open Publication No. 2002-123934).
[0005] At this time a mirror-finish treatment is dispensed to the
magnetic tape substrate where such a coating liquid for forming a
magnetic layer is coated by a calendar device, and thereafter, the
substrate is wound. In addition, the magnetic tape bulk roll is
stored, for example, at an ambient temperature of around 70 degrees
Celsius for a predetermined time (for example, around 36 hours) in
a space adjusted in a state of a low humidity, and a strain of a
base due to such hot curing of a coated film is relieved.
[0006] In addition, on the other side of the magnetic tape
substrate is formed, for example, a back coat layer containing
carbon black like a rough particle of 150 to 300 nm in average
particle size. Then forming a minute convexity on a surface of the
back coat layer and decreasing a contact area by such the carbon
black like the rough particle, a decrease of a friction coefficient
and a running stability are improved.
[0007] Whereas, if the minute convexity is formed on the surface of
the back coat layer, it contacts the surface of the magnetic layer
in a step of winding the magnetic tape substrate and manufacturing
the magnetic tape bulk roll. Then, if leaving the magnetic tape
bulk roll for a long time in the state and/or heating it, there is
a problem that a minute concavity results in being formed on the
surface of the magnetic layer.
[0008] If there exists a concavity on a surface of a data recording
layer of a tape-form recoding medium represented by such the
magnetic tape described above, an occurrence frequency of a dropout
(signal dropout) in reading/writing data increases, and thereby a
quality of the tape-form recoding medium results in lowering. In
addition, because as a track width narrows, an influence of such
the concavity becomes larger, it is a large obstacle in increasing
a recording capacity (recording density) of the tape-form recoding
medium.
[0009] Consequently, a tape-form recoding medium more superior in
running stability and less in occurrence frequency of a dropout,
and a manufacturing method thereof are strongly requested. In
addition, a tape-form recoding medium, where even if a recording
capacity is increased, the occurrence frequency of the dropout does
not increase, and a manufacturing method thereof are strongly
requested.
SUMMARY OF THE INVENTION
[0010] As a result of devoting themselves to a study, the inventors
have discovered that: a concavity formed on a surface of a magnetic
tape is recovered if a raw web is wound with a predetermined
tension, and then the magnetic tape is rewound and heated. The
present invention is performed, based on such the discovery.
[0011] A first aspect of the present invention is a manufacturing
method of a tape-form recoding medium comprising: a raw web
manufacturing process of forming a data recoding layer on one side
of a substrate and a back coat layer having a minute convexity on
the other side thereof, and thus manufacturing raw web of the
tape-form recoding medium; a raw web winding process of winding the
raw web with a predetermined tension; a raw web rewinding process
of rewinding the raw web; and a raw web heating process of heating
the rewound raw web.
[0012] In accordance with such the method, firstly, a data recoding
layer is formed on one side of a substrate and a back coat layer
having a minute convexity is formed on the other side thereof, and
thereby, raw web of a tape-form recoding medium is manufactured
(raw web manufacturing process). Secondly, the raw web is wound
with a predetermined tension, and is made into a state of a bulk
roll (raw web winding process). At this time a minute convexity of
a back coat layer is pushed to a surface of the data recording
layer and a concavity is formed. Then, if the wound raw web is
rewound (raw web rewinding process) and is heated, the data
recording layer expands and the concavity is recovered.
[0013] Meanwhile, the raw web rewinding process is done in order to
make a storage and a heat treatment (strain relief) thereafter
easily performed.
[0014] Here, because a surface pressure is stronger at a portion
near a core of a bulk roll than at a portion near a surface
thereof, a concavity on a surface of a data recording layer becomes
larger (deeper) at the former portion than at the latter. On the
other hand, if raw web once wound is rewound, the raw web wound
near the core of the bulk roll in firstly being wound results in
moving near the surface of the bulk roll. Therefore, the surface
pressure applied to the larger portion in concavity becomes less,
and thus it is enabled to effectively recover the concavity.
Meanwhile, with respect to the raw web wound near the surface of
the bulk roll, because the concavity is originally smaller and
further a tension when rewound lessens, it is enabled to recover
the concavity. In addition, because positions of a minute convexity
and the concavity are displaced by being rewound, it becomes easier
for the concavity to recover.
[0015] Meanwhile, although a tension of raw web in the raw web
rewinding process is not limited, it may also be adapted to rewind
the raw web with a tension smaller (weaker) than that of the raw
web in the raw web winding process.
[0016] Here, a data recording layer may also be any one of a
magnetic layer for recording a change of a magnetic field as a
signal and an optical recording layer containing a metal material
and an organic dye recording material that cause a crystalline
change (phase change) by radiation of a laser light.
[0017] In addition, a width of raw web may be any one of the width
(for example, around 1 m) of being able to form a plurality of
tape-form recoding media by being slit and a width (for example,
1/2 inch (12.65 mm)) corresponding to one tape-form recoding
medium.
[0018] A second aspect of the present invention is the
manufacturing method of the tape-form recoding medium described in
the first aspect of the invention, which the method further
comprises a strain relief process of heating the raw web wound and
relieving a strain of the raw web after the raw web winding process
and before the raw web rewinding process.
[0019] In accordance with such the method, because a strain of raw
web, for example, such a strain of a substrate is relieved by
drying a coated data recording layer, it is enabled to improve a
quality of the tape-form recoding medium. In order to relieve the
strain of the raw web, it is effective to leave the raw web for a
predetermined time under a high temperature environment. At this
time, although because the raw web is warmed and tends to be
deformed, the minute convexity of the back coat layer is pushed to
the surface of the data recording layer and a concavity tends to be
formed; however, because the concavity can be recovered by the raw
web rewinding process and the raw web heating process, the quality
of the tape-form recoding medium does not lower.
[0020] A third aspect of the present invention is the manufacturing
method of the tape-form recoding medium described in the first
aspect of the invention, which the method further comprises a raw
web slitting process of slitting the raw web after the raw web
winding process and before the raw web rewinding process, wherein
the raw web rewinding process winds the slit raw web.
[0021] In addition, a fourth aspect of the present invention is the
manufacturing method of the tape-form recoding medium described in
the second aspect of the invention, which the method further
comprises a raw web slitting process of slitting the raw web after
the strain relief process and before the raw web rewinding process,
wherein the raw web rewinding process winds the slit raw web.
[0022] In accordance with such the method, because wide raw web is
slit and then is rewound, it is enabled to narrow a width of the
raw web in the raw web heating process. Therefore, a heating effect
results in early and uniformly reaching till a middle portion in
width directions of the raw web, and thus it is enabled to
effectively recover a concavity on a surface of a data recording
layer.
[0023] A fifth aspect of the present invention is the manufacturing
method of the tape-form recoding medium described in any one of the
first to fourth aspects of the invention, wherein the raw web is
rewound on a hub having a taper on a tape winding face in the raw
web rewinding process.
[0024] In accordance with such the method, because raw web is
rewound on a hub (hereinafter referred to as "taper hub" in some
case) having a taper on a tape winding face in the raw web
rewinding process, the rewound raw web becomes a state of being
wound on the taper hub. Then because the raw web is heated in the
state of being wound on the taper hub in the following raw web
heating process, a concavity on a surface of a data recording layer
recovers and a curvature results in being given to the raw web. At
this time, if a width of the raw web is adjusted to that of the
tape-form recoding medium at a step before the raw web is rewound
on the taper hub, it is enabled to obtain the tape-form recoding
medium where there exists no concavity on the data recording layer
and the curvature is given in width directions along longitudinal
directions. As an adjustment method of a tape width, raw web having
a width matching that of a tape-form recoding medium of an object
may be initially used, or raw web may also be slit to a width of
the tape-form recoding medium, providing the process of slitting
the raw web before the raw web heating process, as described in the
third and fourth aspects.
[0025] Meanwhile, the data recording layer is a magnetic layer and
preferably 1 to 150 nm in thickness. In order to increase a memory
capacity of a tape-form recoding medium, it is requested to thin
the data recording layer, narrowing a width of a data track, and
make the medium higher density; if performing so, an influence of a
concavity of the data recording layer relatively becomes larger,
and an off-track of data results in frequently occurring in a
method of a usual manufacturing method, that is, the method of
rewinding raw web and not heating it. On the other hand, if the
invention of the application is applied to manufacturing a magnetic
tape of a higher recording density of which a thickness of a
magnetic layer is 1 to 150 nm, because the concavity of the data
recording layer can be recovered, the off-track does not occur, for
example, by making a track density 1500 tracks/inch even if the
memory capacity of the tape-form recoding medium is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1A and 1B are illustration drawings schematically
illustrating manufacturing equipment of a magnetic tape; FIGS. 1A
and 1B respectively show apparatuses corresponding from a raw web
manufacturing process to a strain relief process and from a raw web
slitting process to a raw web heating process.
[0027] FIGS. 2A and 2B are enlarged section drawings showing a
configuration of raw web and a magnetic tape; FIGS. 2A and 2B
respectively show the raw web after a strain relief process and the
magnetic tape after a raw web heating process.
[0028] FIGS. 3A and 3B are views showing a hub; FIG. 3A is a
perspective view of the hub; and FIG. 3B is a section view showing
a state of raw web being wound.
[0029] FIG. 4 is a plan view showing a magnetic tape after being
heated with a heating apparatus.
[0030] FIG. 5 is a flowchart showing a manufacturing method of a
magnetic tape related to an embodiment of the present
invention.
[0031] FIG. 6 is a table showing a test condition and measurement
result of examples and comparison examples.
BEST MODES FOR CARRYING OUT THE INVENTION
[0032] Here will be described a best mode for carrying out the
present invention in detail, referring to drawings as needed. In a
description a same symbol will be appended to a same component, and
a duplicated description will be omitted. Here, as an example will
be described a manufacturing method of a magnetic tape, one of a
tape-form recoding medium.
<Manufacturing Equipment of Magnetic Tape>
[0033] Firstly will be described manufacturing equipment of a
magnetic tape for realizing a manufacturing method of the magnetic
tape related to the present invention.
[0034] The manufacturing equipment of the magnetic tape is as shown
in FIGS. 1A and 1B configured with a raw web manufacturing
apparatus 10 for manufacturing raw web 1, a strain relief apparatus
20 for reducing a strain of the raw web 1, a raw web slitter 30 for
slitting the raw web 1 into a width of a magnetic tape MT, and a
heating apparatus 40 for heating the slit raw web 1.
[0035] The raw web manufacturing apparatus 10 comprises, as shown
in FIG. 1A, a sending-out shaft SH1 for sending out a substrate 2,
a coater 11 for coating a magnetic-layer-use coating liquid and a
back-coat-layer-use coating liquid on the substrate 2, a dryer 12
for drying the coated coating liquids, a calendar device 13 for
smoothly processing a surface of the dried magnetic-layer-use
coating liquid, and a winding shaft SH2 of a winding core for
winding the substrate 2 (that is, raw web 1) where a magnetic layer
3 and a back coat layer 4 (see FIG. 2) are formed. In addition, at
an upstream side of the coater 11 and a downstream side of the
calendar device 13 are respectively provided pinch rollers P and
capstan rollers C for carrying the raw web 1 or the substrate 2. In
addition, on a running path of the raw web 1 and the substrate 2
are provided guide rollers G, regulating the running path.
[0036] The sending-out shaft SH1 is a shaft for attaching a
substrate roll R1 consisting of the substrate 2 wound around like a
roll, and sends out the substrate 2 onto a running path by being
rotated with a driving apparatus (not shown). The sent-out
substrate 2 is adapted to be carried to the coater 11 by the pinch
roller P and the capstan roller C.
[0037] Here, the substrate 2 is a film-form member becoming a base
of the magnetic tape MT, and it is preferable to use, for example,
a synthetic resin film such as polyesters, polyolefins (for
example, polypropylene), cellulose derivatives, polycarbonate,
polyamide, polyimide.
[0038] The coater 11 is an apparatus for coating a
magnetic-layer-use coating liquid on a front side of the substrate
2 and a back-coat-layer-use coating liquid on a back side. The
coater 11 can be selected out of known apparatuses as needed. For
example, although not shown, respectively disposing two members
comprising through holes for vomiting a coating liquid so as to
contact the front side and back side of the substrate 2 and making
the two members run while making the front and back sides contact
the two members for vomiting the coating liquid from the through
holes, and thereby, it also may be adapted to coat the coating
liquid on the substrate 2.
[0039] Here, the magnetic-layer-use coating liquid is configured to
mainly contain a ferromagnetic powder, a bonding agent, and an
organic solvent. In addition, the back-coat-layer-use coating
liquid is configured to mainly contain carbon black and a bonding
agent for forming minute convexities 4a (see FIGS. 2A and 2B). A
particle diameter of the carbon black is preferably around 150 to
300 nm. In addition, according to a method similar to the above, an
under coat layer and/or a non-magnetic layer may also be formed
between the substrate 2 and the magnetic layer 3. Meanwhile, to the
back-coat-layer-use coating liquid are added a dispersing agent, a
lubricant, an antistatic agent, a plasticizer, a stabilizer, and
antirust.
[0040] As a ferromagnetic powder can be used, for example, a
ferromagnetic iron oxide particle such as .gamma.-Fe.sub.2O.sub.3,
Fe.sub.3O.sub.4, and cobalt coated y-Fe.sub.2O.sub.3; a
ferromagnetic dioxide chrome particle; a ferromagnetic metal
particle consisting of metal such as Fe, Co, and Ni, and alloy
containing these; a hexagonal ferrite particulate like a hexagonal
plate; and the like.
[0041] In addition, as a bonding agent can be used a polymer such
as urethane, vinyl chloride, vinyl acetate, vinyl alcohol,
vinylidene chloride, acrylic ester, styrene, butadiene, and acrylic
nitrile; a copolymer where not less than two kinds of these are
combined; polyester resin; epoxy resin; and the like.
[0042] As an organic solvent can be used such ethers, esters,
ketones, aromatic hydrocarbon, aliphatic hydrocarbon, and
chlorinated hydrocarbon.
[0043] The dryer 12 is an apparatus for drying and curing a
magnetic-layer-use coating liquid and a back-coat-layer-use coating
liquid coated on the substrate 2. The dryer 12 is adapted, for
example, to add heat to the substrate 2 passing inside the dryer 12
and to dry the coating liquids coated on the substrate 2.
[0044] The calendar device 13 is an apparatus for smoothing the
front side of the magnetic layer 3. The calendar device 13
comprises two rollers, and is adapted to pinch and pressurize
between the rollers the substrate 2 where the magnetic layer 3 and
the back coat layer 4 are formed. Meanwhile, a surface roughness of
the magnetic layer 3 and the back coat layer 4 can be adjusted by
such a material, surface property, and pressure of the rollers
used. The coating liquids are dried and cured, thereby the magnetic
layer 3 and the back coat layer 4 are respectively formed on the
front and back sides of the substrate 2, and thus the raw web 1 is
formed.
[0045] The winding shaft SH2 of a winding core winds the raw web 1
manufactured. The winding shaft SH2 is adapted to wind the raw web
1 carried by being rotated with a driving apparatus (not shown).
The wound raw web 1 becomes a bulk roll R2. The driving apparatus
is configured to be able to adjust a rotation torque by a torque
adjustment mechanism (not shown) and thereby to adjust a winding
tension of the raw web 1. As a driving apparatus, for example, such
a voltage control alternating motor can be used. In addition, as a
torque adjustment mechanism, for example, a voltage control
apparatus such as an OP (Operational) amp can be used.
[0046] The strain relief apparatus 20 is an apparatus for reducing
a strain accumulated in the raw web 1. The strain relief apparatus
20 comprises a storing unit 21 for storing the bulk roll R2 and a
heater 22 for heating an inner space of the storing unit 21. For
example, if a coating liquid coated on the substrate 2 is dried and
cured and/or the substrate 2 itself is heated, a strain is
accumulated in the raw web 1. The strain relief apparatus 20
relieves a stress by heating the raw web 1, and thereby removes the
strain.
[0047] FIG. 2A is a drawing showing the raw web 1 after taken out
of the strain relief apparatus 20.
[0048] Because the back coat layer 4 contains carbon black of a
predetermined particle diameter, the minute convexities 4a are
formed with the carbon black. By such the minute convexities 4a is
decreased a friction between the magnetic layer 3 and the back coat
layer 4, and a running stability of the magnetic tape MT is
improved.
[0049] On the other hand, because the raw web 1 is wound like a
roll, the minute convexities 4a of the back coat layer 4 of the raw
web 1 wound on the front side of the magnetic layer 3 result in
contacting that of the magnetic layer 3 of the raw web 1 wound
inside (shaft side). Then because the raw web 1 is warmed by the
strain relief apparatus 20 in a state of the bulk roll R2 in order
to remove an accumulated strain, it tends to be deformed.
Therefore, as shown in FIG. 2A, concavities 3a corresponding to the
convexities 4a result in being formed on the front side of the
magnetic layer 3.
[0050] A description will be continued, returning to FIGS. 1A and
1B.
[0051] The raw web slitter 30 comprises, as shown in FIG. 1B, a
sending-out shaft SH3 where the bulk roll R2 is attached, a cutter
31 for slitting the raw web 1, hubs 32, 32 of other winding cores.
In addition, at upstream sides of the cutter 31 and the hubs 32, 32
are disposed the pinch rollers P and the capstan rollers C,
respectively. In addition, at the downstream side of the cutter 31
are provided the guide rollers G for leading the slit raw web 1 to
each of the hubs 32, 32.
[0052] The sending-out shaft SH3 is a shaft for attaching the bulk
roll R2 where a strain is relieved, and sends out the raw web 1
onto a running path by being rotated by a driving apparatus (not
shown). The sent-out raw web 1 is adapted to be carried to the
cutter 31 by the pinch roller P and the capstan roller C.
[0053] The cutter 31 slits the raw web 1 into a width of the
magnetic tape MT, and in the embodiment, is configured with a round
knife cutter. The slit raw web 1 is led to the hubs 32, 32 by the
guide rollers G, G, respectively.
[0054] Each of the hubs 32, 32 winds the raw web 1 slit into a same
width. The hub 32 is connected to a driving apparatus (not shown)
and adapted to be rotatable. The driving apparatus is configured to
be able to adjust a rotation torque by a torque adjustment
mechanism (not shown) and thereby to adjust a tension for winding
the raw web 1. As a driving apparatus, for example, such a voltage
control alternating motor can be used. In addition, as a torque
adjustment mechanism, for example, a voltage control apparatus such
as an OP amp can be used.
[0055] The hub 32 related to the embodiment expresses a truncated
cone form shown in FIG. 3A. In other words, a winding face 32a of
the hub 32 is tilted by .theta. degree with respect to an axial
direction thereof. Therefore, a pancake PC formed by winding the
raw web 1 around the winding face 32a of the hub 32 becomes like a
mortar as shown in FIG. 3B. In addition, if rewinding the raw web 1
on the hub 32, the raw web 1 positioned near a core of a bulk roll
2 results in being positioned near a surface of the pancake PC; the
raw web 1 positioned near a surface of the bulk roll 2 results in
being positioned near a core (hub 32) of the pancake PC.
[0056] The heating apparatus 40 recovers the concavities 3a formed
on the magnetic layer 3 of the raw web 1 by heating (performing a
heat treatment for) the raw web 1. As shown in FIG. 1B, the heating
apparatus 40 comprises a storing unit 41 for storing pancakes PC,
the heater 42 for heating a space within the storing unit 41, and a
humidifier 43 for giving a humidity to the space within the unit
41. It is preferable in the storing unit 41 to use a material
higher in adiathermancy and to form a size that can store a
plurality of pancakes PC.
[0057] A temperature within the storing unit 41 is preferably
around 40 to 60 degrees Celsius, and more preferably around 50 to
60 degrees Celsius. In addition, a humidity is preferably around 20
to 80%, and more preferably around 40 to 60%. In addition, a
storing time is preferably around 12 to 72 hours, and more
preferably around 12 to 48 hours. The raw web 1 is left inside the
storing unit 41 in a state of the pancakes PC, and the concavities
3a are adapted to recover. Meanwhile, because it is preferable that
there exists a proper humidity in order to recover the concavities
3a, in the embodiment is provided the humidifier 43 inside the
heating apparatus 40.
[0058] FIG. 2B is an enlarged perspective view showing the magnetic
tape MT after being heated by the heating apparatus 40.
[0059] The raw web 1 is relieved in stress by being heated, and as
shown in FIG. 2B, the concavities 3a formed on the surface of the
magnetic layer 3 recover. At this time, because the raw web 1
positioned near the core of the bulk roll 2 is moved near the
surface of the pancake PC by being rewound on the hub 32, a surface
pressure becomes smaller and a strain tends to recover. In
addition, because positions of the minute convexities 4a and the
concavities 3a are displaced due to the raw web 1 being rewound,
the concavities 3a result in tending to recover. Furthermore,
because the raw web 1 is rewound on the hub 32 with a tension
smaller than that in being wound on the winding shaft SH2 in the
raw web manufacturing apparatus 10, the concavities 3a of the raw
web 1 positioned near the core (hub 32) of the pancake PC also tend
to recover.
[0060] Meanwhile, although in the embodiment the raw web 1 is
assumed to be rewound on the hub 32 with a tension smaller than
that in being wound on the winding shaft SH2 in the raw web
manufacturing apparatus 10, the embodiment is not limited thereto;
the raw web 1 may also be assumed to be rewound on the hub 32 with
a tension equal to or larger (stronger) than that in being wound on
the winding shaft SH2 in the apparatus 10. In such the case it is
enabled to recover the concavities 3a of the raw web 1 because of
the above reasons.
[0061] The raw web 1 wound around the taper hub 32 is heated by the
heating apparatus 40 and thereby, as shown in FIG. 4, becomes a
state of being curved in width directions along longitudinal
directions thereof. To describe more in detail, in the raw web 1
wound around like a mortar because a circumference of outside (left
in FIG. 3B) of the mortar is longer than that of inside (right in
FIG. 3B) thereof, a side edge 6a positioned at the outside of the
mortar results in being elongated more than a side edge 6b
positioned at the inside of thereof. As a result, the raw web 1
results in being curved in a form of making the side edge 6a side
convex. Thus the magnetic tape MT is completed.
[0062] Meanwhile, the magnetic tape MT is preferably around 0.5 mm
to 4.0 mm in a maximum distance D between the side edge 6a and a
baseline S connecting two points on the side edge 6a distant by a
distance L=1 m as shown in FIG. 4. Thus if a winding tendency of a
predetermined curved form is given to the magnetic tape MT, a
preferable winding form is ensured, a tape running is stabilized,
and a performance of a servo tracking is improved.
[0063] Subsequently, the manufacturing method of the magnetic tape
MT will be described.
[0064] As shown in FIG. 5 (see FIGS. 1A to 4 as needed), the
manufacturing method of the magnetic tape MT related to the
embodiment is configured with: a raw web manufacturing process S1
of forming the magnetic layer 3 and the back coat layer 4 on the
substrate 2; a raw web winding process S2 of winding the raw web 1
manufactured; a strain relief process S3 of relieving a strain
accumulated in the raw web 1 in the manufacturing processes; a raw
web slitting process S4 of cutting the raw,web 1 into a width of
the magnetic tape MT; a raw web rewinding process S5 of rewinding
the slit raw web 1; and a raw web heating process S6 of heating the
rewound raw web 1 and recovering the concavities 3a of the magnetic
layer 3. Each of these processes is realized by the manufacturing
equipment of the magnetic tape MT shown in FIGS. 1A and 1B.
Hereafter will be described the manufacturing method of the
magnetic tape MT in detail, referring to FIGS. 1A to 5.
<<Raw Web Manufacturing Process>>
[0065] Firstly, the substrate 2 sent out from the substrate roll R1
is, as shown in FIG. 1A, carried by the pinch roller P and the
capstan roller C to the coater 11. The coater 11 coats a
magnetic-layer-use coating liquid on the front side of the
substrate 2 and a back-coat-layer-use coating liquid on the back
side thereof. The substrate 2 where the magnetic-layer-use coating
liquid and the back-coat-layer-use coating liquid are coated is
carried to the dryer 12. The dryer 12 dries and cures the
magnetic-layer-use coating liquid and the back-coat-layer-use
coating liquid. Thus, on the front side and back side of the
substrate 2 are formed the magnetic layer 3 and the back coat layer
4, respectively. The substrate 2 where the magnetic layer 3 and the
back coat layer 4 are formed is carried to the calendar device 13,
and the front side of the magnetic layer 3 is smoothed by the
calendar device 13. Thus the raw web 1 is manufactured.
<<Raw Web Winding Process>>
[0066] The raw web 1 where the front side of the magnetic layer 3
is smoothed is wound with a predetermined tension by the winding
shaft SH2, and becomes the bulk roll R2. Thus the
minute,convexities 4a of the back coat layer 4 are pushed to the
front side of the magnetic layer 3 and result in digging into
it.
<<Strain Relief Process>>
[0067] The bulk roll R2 is stored within the storing unit 21 of the
strain relief apparatus 20 and is left for around 36 hours in a
space made a state of, for example, a temperature of 70 degrees
Celsius and a lower humidity. Thus a strain accumulated in the raw
web 1 is relieved. On the other hand, because the front side of the
magnetic layer 3 results in being warmed in a state of being pushed
to the minute convexities 4a of the back coat layer 4, the
concavities 3a result in being formed at a portion where the front
side contacts the minute convexities 4a (see FIG. 2A).
<<Raw Web Slitting Process>
[0068] The bulk roll R2 where a strain is relieved is set, as shown
in FIG. 1B, on the sending-out shaft SH3 of the raw web slitter 30.
The raw web 1 sent out from the bulk roll R2 is carried to the
cutter 31 by the pinch roller P and the capstan roller C. The
cutter 31 slits the carried raw web 1 so as to be equal to a width
of the magnetic tape MT.
<<Raw Web Rewinding Process>>
[0069] The slit raw web 1 is, as shown in FIG. 1B, branched along
the guide rollers G and is wound on each of the hubs 32, 32. At
this time, by adjusting a torque of a driving device for rotating
the hub 32, the raw web 1 is adapted to be wound on the hub 32 with
a tension weaker than that of when the bulk roll 2 is formed. Thus
a force by which the back coat layer 4 pushes the magnetic layer 3
becomes weaker, and a recovery of the concavities 3a becomes
easier.
[0070] Meanwhile, because the hub 32 has a taper on the winding
face 32a as shown in FIG. 3A, the raw web 1 rewound on the hub 32
becomes the pancake PC expressing like a mortar (see FIG. 3B).
<<Raw Web Heating Process>>
[0071] The pancakes PC, PC made like a mortar are stored within the
storing unit 41 of the heating apparatus 40, and are left for
around 24 hours in a space adjusted to, for example, a temperature
of 60 degrees Celsius and a humidity of 50%. Because the raw web 1
positioned near the core of the bulk roll 2 is moved near the
surface of the pancake PC by being rewound on the hub 32, a surface
pressure becomes smaller and a strain is recovered. In addition,
because the raw web 1 is rewound with a tension weaker than the
bulk roll 2, the concavities 3a is recovered (see FIG. 2B) by such
the heat treatment. Furthermore, because the raw web 1 is wound on
the taper hub 32, one side edge 6a (see FIG. 4) results in being
warmed in a state of being pulled more than the other side edge 6b.
Thus the one side edge 6a is elongated, and thereby the magnetic
tape MT is formed that is curved in width directions along
longitudinal directions thereof.
[0072] Thus, in accordance with the manufacturing method of the
magnetic tape MT related to the embodiment, by rewinding the slit
raw web 1 on the taper hub 32 and heating the web 1, the curved
magnetic tape MT can be manufactured while recovering the
concavities 3a formed on the surface of the magnetic layer 3.
EXAMPLE
[0073] Although examples are described below, the present invention
is not limited thereto. Meanwhile, "part" in the examples and
comparison examples shows "weight part."
Example 1
[0074] Out of undercoat layer coating liquid compositions below,
kneading a first agent with a kneader, then adding a second agent
and stirring it, dispersing it by a sand mill with making a staying
time 90 minutes, and after adding a third agent thereto and
stirring and filtering it, it was made an undercoat layer coating
liquid.
[0075] In addition, other than this, out of magnetic-layer-use
coating liquids shown below, kneading a first agent with a kneader,
then dispersing it by a sand mill with making a staying time 60
minutes, and adding a second agent of the coating liquid
compositions thereto and stirring and filtering it, thus it was
made a magnetic-layer-use coating liquid.
<<Undercoat Layer Coating liquid Composition>>
(First Agent)
[0076] Iron oxide powder (particle diameter: 0.15.times.0.02
.mu.m): 70 parts [0077] Alumina (.alpha. ratio: 50%, particle
diameter: 0.05 .mu.m): 8 parts [0078] Carbon black (particle
diameter: 15 nm): 25 parts [0079] Stearic acid/butyl stearate
(50/50): 3.0 parts Vinyl chloride copolymer (containing-SO.sub.3Na
group: 1.2.times.10.sup.-4 equivalent/g): 10 parts Polyester
urethane resin (Tg: 40 degrees Celsius, containing-SO.sub.3Na
group: 1.times.10.sup.-4 equivalent/g): 4.4 parts [0080]
Cyclohexanone: 30 parts [0081] Methylethylketone: 60 parts (Second
Agent) [0082] Butyl stearate: 3 parts [0083] Oleyl oleate: 5 parts
[0084] Cyclohexanone: 40 parts [0085] Methylethylketone: 60 parts
[0086] Toluene: 15 parts (Third Agent) [0087] Polyisocyanate: 1.5
parts [0088] Cyclohexanone: 8 parts [0089] Methylethylketone: 18
parts [0090] Toluene: 8 parts <Magnetic-Layer-Use Coating liquid
Composition>> (First Agent) [0091] Ferromagnetic metal powder
(Co/Fe, 30 atomic %; Y/(Fe+Co), 3 atomic %; [0092] Al/(Fe+Co), 5 wt
%; Ca/Fe, 0.002; .sigma.s, 155 Am.sup.2/kg; Hc, 188.2 kA/m; photo
curing, 9.4; long axis length, 0.10 .mu.m): 100 parts [0093] Vinyl
chloride hydroxypropyl acrylate copolymer (containing-SO.sub.3Na
group: 0.7.times.10.sup.-4 equivalent/g): 13.0 parts [0094]
Polyester urethane resin (containing-SO.sub.3Na group:
1.times.10.sup.-4 equivalent/g): 5.5 parts .alpha.-alumina (average
particle diameter: 0.15 .mu.m): 12 parts [0095] .alpha.-alumina
(average particle diameter: 0.05 .mu.m): 4 parts [0096] Carbon
black (average particle diameter, 50 nm; DBP (dibutyl phthalate)
oil absorption amount, 72 cc/100 g): 40 parts [0097] Methyl acid
phosphate: 2 parts [0098] Stearic acid: 1.5 parts [0099] Oleyl
oleate: 5 parts [0100] Cyclohexanone: 70 parts [0101]
Methylethylketone: 250 parts (Second Agent) [0102] Polyisocyanate:
2.0 parts [0103] Methylethylketone: 167 parts
[0104] In addition, after kneading a back-coat-layer-use coating
liquid composition shown below with a continuous kneader, it was
dispersed with using a sand mill. Then adding 40 parts of
polyisocyanate and 1000 parts of methylethylketone and then
filtering it with an average hole diameter of 1 .mu.m, it was made
a back-coat-layer-use coating liquid.
<<Back-Coat-Layer-Use Coating liquid Composition>>
[0105] Fine particle carbon black powder (average particle size: 34
nm): 100 parts [0106] Rough particle carbon black powder (average
particle size: 80 nm): 10 parts [0107] .alpha.-iron oxide particle
(average particle size: 0.1 .mu.m, Mohs hardness: 5): 20 parts
[0108] .alpha.-alumina (hard property inorganic powder: average
particle size, 0.2 .mu.m, Mohs hardness: 9): 5 parts [0109]
Nitrocellulose resin: 50 parts [0110] Polyurethane resin: 50 parts
[0111] Polyester resin: 5 parts [0112] Copper oleic (dispersant): 5
parts [0113] Copper phthalocyanine (dispersant): 5 parts [0114]
Methylethylketone: 500 parts [0115] Toluene: 200 parts
[0116] Then, coating the undercoat-layer-use coating liquid on the
substrate 2 consisting of a film made of a polyethylene naphthalete
(PEN) resin of thickness 5 .mu.m so that a thickness of the coating
liquid after drying and a calendar treatment became 1.1 .mu.m on
one side thereof and further coating the magnetic-layer-use coating
liquid with dry-on-wet so that a thickness of the magnetic layer 3
after drying and a calendar treatment became 0.05 .mu.m, treating a
magnetic field orientation, and then drying with using the dryer 12
and an infrared radiation apparatus (not shown), the magnetic layer
3 was formed.
[0117] Thereafter, coating the back-coat-layer-use coating liquid
on the other side (opposite side to the magnetic layer 3) of the
substrate 2 so that a thickness of the coating liquid after drying
became 0.5 .mu.m, the back coat layer 4 was formed. Thus was
obtained the raw web 1 where the magnetic layer 3 was provided on
the one side of the substrate 2; and the back coat layer 4, on the
other side thereof
[0118] Performing a mirror finish treatment for the raw web 1 thus
obtained by a five-high calendar consisting of metal rolls under a
condition of a temperature of 80 degrees Celsius and a linear
pressure of 2 kN/cm (200 kgf/cm), the raw web 1 was wound with a
tension of 50 N/m (5.1 kgf/m). The wound bulk roll 2 was stored for
24 hours at 70 degrees Celsius within an oven (strain relief
apparatus 20). The obtained bulk roll 2 was slit into a width of
12.65 mm (1/2 inch). The slit raw web 1 was wound with a tension of
1 N (102 gf) on the hub 32 made of aluminum of 200 .phi. having a
taper of 0.3 degree. In this case a reference edge was made a
larger side of a hub diameter. The raw web 1 wound on the hub 32
was further stored for 24 hours within an oven (heating apparatus
40) controlled at a temperature of 60 degrees Celsius and a
humidity of 60%.
[0119] With respect to the magnetic tape MT thus manufactured, a
surface polish treatment (air pressure, 0.25 MPa; polish time, 0.1
second) was dispensed by chromium oxide polish tape (KX2000:
chromium oxide average particle diameter, 0.6 .mu.m; surface
roughness, 0.07 .mu.m). Furthermore, after recording a servo signal
in the magnetic layer 3 based on an LTO (Linear Tape Open)
Generation 3 format and then winding the magnetic tape MT in a
cassette, a magnetic tape cartridge was made.
Example 2
[0120] Except that a magnetic material was changed to a barium
ferrite magnetic material below, a magnetic tape cartridge was made
similarly as in the example 1.
[0121] The barium ferrite magnetic material is 2000 nm.sup.3 in
particle volume, 3 in plate ratio, 3000 Oe in Hc, 70 m.sup.2/g in
SSA (Specific Surface Area), and 45 emu/g in .sigma.s; and a
surface treatment was performed thereto with an aluminum
compound.
Example 3
[0122] Except that the substrate 2 to be used was changed to a film
made of a polyethylene terephthalate (PET) resin, the magnetic tape
MT of a was made similarly as in the example 1.
Example 4
[0123] Except that the substrate 2 to be used was changed to a film
made of a polyvinyl alcohol (PA) resin, the magnetic tape MT was
made similarly as in the example 1.
Example 5
[0124] Except that a taper of the hub 32 for a heat treatment was
changed to 0.5 degree, the magnetic tape MT was made similarly as
in the example 1.
Example 6
[0125] Except that a heat treatment time after being wound on the
hub 32 was changed to 12 hours, the magnetic tape MT was made
similarly as in the example 1.
Example 7
[0126] After slitting the raw web 1 of a sputter type magnetic tape
made by methods below into a width of 1/2 inch, the magnetic tape
MT was made with the same heat treatment condition as in the
example 1. Hereafter will be described a making method of the
sputter type magnetic tape.
[0127] Firstly, coating with a gravure coat method an undercoat
liquid consisting of 3-glycidyloxypropyl-trimethoxysilane,
phenyltriethoxysilane, hydrochloric acid, aluminum acetylacetonate,
and ethanol on a substrate similar to that of the example 1, and
then drying and curing the undercoat liquid at 100 degrees Celsius,
an undercoat layer comprising a silicone resin of a thickness of
0.2 .mu.m was made.
[0128] Coating with a gravure coat method a coating liquid, where
silica sol of a particle diameter of 18 nm and the undercoat liquid
was mixed, on the undercoat layer, a convexity of 15 nm in height
was formed in density of 10 pieces/.mu.m.sup.2.
[0129] Next, placing the raw web 1 in a web type sputter apparatus,
carrying a film while tightly contacting it on a water-cooled can
(15 degrees Celsius) for carrying, and forming on the undercoat
layer a barrier layer of a thickness of 20 nm consisting of carbon
(C) and a base layer of a thickness of 40 nm consisting of
ruthenium (Ru) by a DC magnetron sputter method, subsequently, a
magnetic layer of a thickness of 17 nm consisting of
(Cl.sub.70--Pt.sub.20--Cr.sub.10).sub.88--(SiO.sub.2).sub.12 was
formed
[0130] Next, placing the raw web 1 in a web type CVD (Chemical
Vapor Deposition) apparatus, a nitrogen added DCL (Diamond Like
Carbon) protection film of a thickness of 10 nm was formed by an
ion beam plasma CVD method of using a nitrogen gas and an ethylene
gas as a material gas.
[0131] Next, coating a back coat liquid by a wire bar method, where
carbon black, calcium carbonate, stearic acid, nitrocellulose,
polyurethane, isocyanate hardener are dissolved and dispersed in
methylethylketone, and drying the liquid at 100 degrees Celsius, a
back coat layer of a thickness of 0.5 .mu.m was made.
[0132] Then, coating a mixture liquid of stearyl amine and mono
lauryl phosphate of a mol ratio of 1:1 on a surface of the nitrogen
added DCL (Diamond Like Carbon) protection film, a lubrication
layer was made. A coating amount of the liquid was 10 mg/M.sup.2.
In addition, coating with a gravure coat method a solution, where a
perfluoro polyether lubricant (FOMBLIN Z-DOL manufactured by Solvay
Solexis S.A.) having a hydroxyl group at a molecule end was
dissolved in a fluorine lubricant (HFE-7200 manufactured by
SUMITOMO 3M), on a surface of a back coat layer, a lubrication
layer was formed. A coating amount of the solution was 10
mg/M.sup.2.
Comparison Examples 1-3
[0133] Except that a heat treatment was not performed for the raw
web 1 wound on the hub 32 after slitting, magnetic tapes MT was
made similarly as in the example 1.
[0134] Out of the magnetic tapes MT, selecting tapes of which
curvature values are -2 mm, 0 mm, and +3.5 mm, they are made
comparison examples 1, 2, and 3, respectively. Meanwhile, the
curvatures of the comparison examples were given when the raw web 1
was manufactured and wound (see FIG. 1A), that is, when the bulk
roll 2 was formed.
[0135] With respect to the magnetic tapes MT of the examples 1 to 7
and the comparison examples 1 to 3, a measurement was made
according to methods below. A measurement result is shown in FIG.
6.
[0136] Here, "LTM" in FIG. 6 is an abbreviation of "Lateral Tape
Motion" and indicates a fluctuation amount of a running position in
width directions of the magnetic tapes MT. In addition, "PES" is an
abbreviation of "Position Error Signal" and a standard deviation of
an amount unable to be servo followed with respect to a fluctuation
of the running position in the width directions of the magnetic
tapes MT. Meanwhile, the measurement method of each measurement
value shown in FIG. 6 is shown below:
<<Creep Amount>>
[0137] Placing a sample, where the magnetic tape MT was cut out to
a length of 15.00 mm in a longitudinal direction thereof and a
width of 5.00 mm in a width direction thereof, at a chuck portion
of TM-9200 (Thermomechanical Measurement Instrument manufactured by
ULVAC-RIKO, Inc.) and setting a weight so that a stress of 13 MPa
was applied, a deformation amount after 50 hours at 50 degrees
Celsius was measured. The deformation amount after 50 hours at 50
degrees Celsius with respect to an initial length excluding an
elastic deformation portion just after weighting was made a creep
amount. A calculation equation is shown below: Creep amount
(%)=(Length after deformation-Initial length)/Initial
length.times.100. <<Dropout>>
[0138] Recording/reproducing a signal of 130 kfci, measuring a time
(piece) when a reproduced signal was lowered by not less than 50%,
and converting an obtained value to a value per ch (channel) and
meter of the magnetic tape MT, it was made a dropout.
<<LTM>>
[0139] Running the magnetic tape MT at a speed of 5.3 m/section and
measuring a running position of a tape edge at a position of a
magnetic head by a laser displacement meter, a fluctuation amount
of the running position was made the LTM.
<<PES>>
[0140] Running the magnetic tape MT at a speed of 5.3 m/section, a
standard deviation of an amount unable to be servo followed with
respect to a fluctuation of a running position in width directions
of the magnetic tapes MT was made the PES.
<<Edge Damage>>
[0141] Repeatedly and reciprocatingly running the magnetic tape MT
5000 times through a whole length thereof and then observing a tape
edge, a place where the tape edge was folded at a width of not less
than 100 .mu.m was counted. At this time a case of the folded place
being less than five places was made ".sym."; not less than five
places and less than ten places "O"; not less than ten places
"X".
[0142] Meanwhile, in measuring the dropout, the LTM, the PES, and
the edge damage was used a LTO tape drive "3580-L33" manufactured
by IBM Corp.
[0143] As shown in FIG. 6, it is proved that in the examples 1 to 7
where the heat treatment was performed after rewinding, the piece
of the dropout is remarkably reduced, compared to that of the
comparison examples 1 to 3 where the heat treatment was not
performed after rewinding. In addition, it is proved that in the
examples 1 to 7 the creep amount is reduced, compared to that of
the comparison examples 1 to 3. Therefore, it is difficult for the
magnetic tape MT to be deformed and it is suitable for a long time
storage.
[0144] Thus, although the best mode for carrying out the present
invention is described in detail, referring to the drawings, the
invention is not limited thereto, and various variations are
available without departing from the spirit and scope of the
invention.
[0145] For example, although in the embodiment the magnetic layer 3
and the back coat layer 4 are formed by coating system, the
embodiment is not limited thereto, and for example, each of the
layers may also be formed, for example, by any one of a sputter
method and a vapor deposition method.
[0146] In addition, as a coating method by a wet-on-wet system can
be cited the following methods: [0147] (1) A method of using any
one of such a gravure coating apparatus, a roll coating apparatus,
a blade coating apparatus, and an extrusion coating apparatus,
firstly forming a non-magnetic layer on the substrate 2, and then
the magnetic layer 3 by a support-body pressurizing extrusion
coating apparatus while the non-magnetic layer is wet (see Japanese
Patent Laid-Open Publication No. S 60-238179, H1-46186, and
H2-265672); [0148] (2) A method of using a coating apparatus
consisting of a single coating head equipped with two slits for
coating a liquid and almost simultaneously forming the magnetic
layer 3 and a non-magnetic layer (not shown) on the substrate 2
(Japanese Patent Laid-Open Publication No. S63-88080, H2-17921, and
H2-265672); and [0149] (3) A method of using an extrusion coating
apparatus with a backup roller and almost simultaneously forming
the magnetic layer 3 and a non-magnetic layer (not shown) on the
substrate 2 (Japanese Patent Laid-Open Publication No.
H2-174965).
[0150] In addition, although in the embodiment a magnetic tape is
described as an example, the present invention is not limited
thereto and is also applicable, for example, to a tape-form
recording medium such an optical recording tape.
[0151] In addition, in the embodiment, although providing the
strain relief process S3 and using the strain relief apparatus 20,
it is assumed to relieve the strain of the bulk roll R2, the
present invention is not limited thereto; for example, as in a case
that the strain of the raw web 1 is smaller, when it is not
necessary to provide the strain relief process S3, it goes without
saying that such the process may be omitted. Even in a case of the
omission, when making the raw web 1 like a roll, the minute
convexities 4a are pushed to the front side of the magnetic layer 3
and the concavities 3a result in being formed.
[0152] In addition, although the embodiment is adapted to use the
taper hub 32, to give a curvature to the magnetic tape MT, and to
simultaneously recover the concavities 3a of the magnetic layer 3,
it is not limited thereto; it is also available to use a hub
without a taper and to recover the concavities 3a of the magnetic
layer 3 without giving a curvature.
[0153] In addition, in order to heighten the recovery effect of the
concavities 3a, although the embodiment is configured to provide
the heating apparatus 40 with the humidifier 43 and to increase the
humidity of the storing unit 41, the present invention is not
limited thereto and may not comprise the humidifier 43. Even in
such the case it is enabled to recover the concavities 3a by heat
treatment.
* * * * *