JPS5823649B2 - Jiki Tono Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic sheet, and more particularly to a method for manufacturing a magnetic sheet in which the roughness of the surface of a magnetic layer is made more uniform and smooth in multiple directions.

Magnetic sheets are typically made of a flexible strip such as polyethylene terephthalate film or cellulose triacetate film, and are coated with γ-F on one or both sides.
Fine ferromagnetic powders such as e2O3 or CrO3 are combined with thermoplastic resins such as vinyl chloride vinyl acetate copolymers or thermosetting resins such as phenolic resins or mixtures of methacrylate copolymers and diisocyanate prepolymers or reactive types. A magnetic coating liquid obtained by mixing a resin binder, a dispersant, a lubricant, an abrasive, and an organic solvent is applied by air knife coating, gravure coating, or spray coating to form a magnetic layer. The outer diameter is 10crIL~50cIfL and the inner diameter is 0.5 (YllX
This was obtained by cutting the support having the magnetic layer in the range of 3 crIL into a donut shape.

The magnetic sheet is a video sheet recorder (rV
It is called sRJ.

), magnetic signals are recorded on the magnetic layer in a concentric or spiral manner while being rotated and levitated.

In recent years, the magnetic recording density on the magnetic sheet has tended to become higher, and with this, it is desired to further stabilize the touch of the magnetic sheet during rotation and levitation with respect to the magnetic head of the VSH. It became necessary to make the roughness of the layer surface more uniform and smooth.

Therefore, a manufacturing method that has been commonly used in the manufacturing of magnetic tapes and is capable of smoothing out the roughness of the surface of the magnetic layer has been used in the manufacturing of the magnetic sheet.

A typical method for manufacturing the magnetic tape is to transport a long and wide flexible support in the longitudinal direction at a constant speed while adding a binder, additives,
A desired amount of a magnetic coating liquid formed by mixing and dispersing in an organic solvent, etc. is coated on one side of the support by gravure roll coating, air knife coating, or spray coating to form a magnetic layer, and then After the magnetic layer is continuously dried and wound into a coil, the long and wide support is unwound at a constant speed and sent to a calendar roller consisting of metal rollers arranged above and below. It was.

The long and wide support whose magnetic layer surface has been rolled in the longitudinal direction by the calendar roller is further fed into a slitter and shredded to a desired width, and then wound into a coil around a winding core member. Magnetic tapes such as those mentioned above were manufactured in the 1990s.

Note that, depending on the manufacturing conditions of the magnetic tape, the above-mentioned calendering of the surface of the magnetic layer was sometimes carried out immediately after drying the magnetic layer.

However, when the magnetic sheet was manufactured according to the conventional manufacturing method as described above, the following drawbacks occurred in the magnetic sheet.

(1) After calendering the support in its longitudinal direction, the surface of the magnetic layer of the magnetic sheet obtained by cutting into a donut shape is oriented in one direction (hereinafter referred to as the "X direction").

) in the other direction (hereinafter referred to as "
"Y direction".

) is not rolled, the relative difference in the surface roughness of the magnetic layer surface in the two directions, that is, the X and Y directions, becomes significant. Unlike the magnetic sheet that is recorded or reproduced, the magnetic sheet is magnetically recorded concentrically or spirally while floating around the rotation axis of the VSR, and is further reproduced. There is a drawback in that the contact of the magnetic layer as it passes varies markedly due to the difference in surface roughness as described above, making output fluctuations during one rotation more noticeable.

(2) If calendaring is performed only in the X direction as described above, the magnetic sheet cut into a donut shape will be encouraged to curl in a directionally biased manner, so that the surface of the magnetic layer may be pressed against the magnetic head. This has the drawback that the magnetic sheet becomes unstable, resulting in large fluctuations in the output of the magnetic sheet.

It is an object of the present invention to provide a method for manufacturing the magnetic sheet, which eliminates the drawbacks of the conventional manufacturing method as described above, makes the surface roughness of the magnetic layer more uniform and smoother in multiple directions, and causes less curling. That is.

A further object of the present invention is to reduce the surface roughness of the magnetic layer in at least two directions so that the maximum height (Hmax) of each surface roughness is 0.5μ or less, and the maximum height (Hmax) of each of the two directions.
This is achieved by a method for manufacturing a magnetic sheet, which is characterized in that the surface is finished so that the difference in max) is 0.1μ or less.

Hereinafter, one embodiment of the present invention will be described in detail based on the attached drawings.

In FIG. 1, W is polyethylene terephthalate,
Polyesters such as polyethylene-2,6-naphthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose guiacetate, cellulose triacetate, cellulose acetate butyrate, and cellulose acetate glopionate, polyvinyl chloride, polyvinylidene chloride vinyl resins such as
In addition to plastics such as polycarbonate, polyimide, and polyamideimide, depending on the application, non-magnetic metals such as aluminum and copper, paper, baryta, or polyethylene, polypropylene, and ethylene-butene copolymers with 2 to 1 carbon atoms may be used.
A long and wide support made of paper coated or laminated with α-polyolefin of 0.0 and transparent or opaque depending on the purpose of use of the magnetic recording medium is transported in the longitudinal direction at a constant speed. , specifically,
-14090 Publication, Japanese Patent Publication No. 18372, Japanese Patent Publication No. 47-22062, Japanese Patent Publication No. 47-22062, Japanese Patent Publication No. 47-22513
Publication No. 46-28466, Publication No. 46-28466, Publication No. 46-28466
38755, Japanese Patent Publication No. 47-4286, Japanese Patent Publication No. 12422, Japanese Patent Publication No. 47-17284, Japanese Patent Publication No. 47-18509, Japanese Patent Publication No. 47-18509, Japanese Patent Publication No. 1987-1
γ-Fe2O3,C described in Publication No. 8573 etc.
o-containing r-Fe203, Fe 304°, Co-containing Fe3O4, Co-containing Fe3O4, CrO2, Co
-N1-P alloy, Fe-Co-Ni alloy, etc., known ferromagnetic fine powder
No. 8, 39-19282″'' No. 40-5349, 4
0-7, No. 20907, No. 41-9463, No. 41-14059, No. 41-16985, No. 42-6428, 42-11
No. 621, No. 43-4623, No. 43-15206, 4
No. 4-2889, No. 44-17947, No. 44-1823
No. 2, No. 45-14020, No. 45-14500, 47
-18573, 47-22063, 47-2206
No. 4, 47-22068” No. 47-22069, 4
Thermoplastic resins described in publications such as No. 7-7, No. 22070, and No. 47-27886, which have a softening temperature of 150°C or less, an average molecular weight of 10,000 to 200,000, and a degree of polymerization of about 200 to 5.
For example, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic ester acrylonitrile copolymer, acrylic ester vinylidene chloride copolymer, acrylic ester Styrene copolymer, methacrylic acid ester acrylonitrile copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer Polyamide resin polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose gropione), nitro cellulose, etc.), styrene butadiene copolymer, polyester resin, chlorovinyl ether acrylic acid Ester copolymers, amine resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof, or Japanese Patent Publication Nos. 39-L8103, 40-9779, 41-719
No. 2, No. 41-8016, No. 41-14275, 42-
No. 18179, No. 43-12081, No. 44-28023
No. 45-14501, No. 45-24902, 46-
No. 13103, No. 47-22065, No. 47-22066
No., No. 47-22067, No. 47-22072, 47-
No. 22073, No. 47-28045, No. 47-28048
Thermosetting resins or reactive resins described in publications such as No. 47-28922, and in the state of coating liquid, 2 × 10
It has a molecular weight of 5 or less, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Alternatively, those that do not melt are preferred, and specific examples include phenol resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reactive resins, and epoxy resins.
Polyamide resin, nitrocellulose melamine resin, mixture of high molecular weight polyester resin and incyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer, mixture of polyester polyol and polyisocyanate, urea formaldehyde resin, low molecular weight glycol/high A binder consisting of a molecular diol/triphenylmethane triisocyanate mixture, a polyamine resin, and a mixture thereof is mixed in a weight ratio of 10 to 10 parts by weight of the binder to 100 parts by weight of ferromagnetic fine powder.
Mix in a range of 200 parts by weight, and further add a dispersant, a lubricant,
A magnetic coating liquid obtained by adding an abrasive, an organic solvent, etc. was applied to one side of the support as described in detail in "Coating Engineering" published by Asakura Shoten, pages 253 to 277 (published on March 20, 1972). Apply the desired amount using the listed air doctor coat, blade coat, air knife coat, squeeze coat, tip coat, reverse roll coat, transfer roll coat, gravure coat, kiss coat, cast coat, spray coat method, etc. This is a long and wide flexible magnetic recording medium with a magnetic layer.

Reference numeral 1 denotes a magnetic layer forming step comprising a means for delivering the support, a means for applying a magnetic coating liquid (none of which are shown), a drying means 2 and a winding means 3.

4 is a magnetic sheet processing step comprising a rewinding means 5 for the magnetic recording medium W, a vertical cutting means 6, a horizontal cutting means 1, a circular punching means 8, and a surface finishing means 9. .

The support body, which usually has a width of 0.3772 to 1.5 doors, is continuously fed from the delivery means to the coating means at a constant speed, and the magnetic coating liquid is applied to one side of the support body by the coating means. Further, by transporting the medium at a constant speed within the drying means 2, the long and wide flexible magnetic recording medium W having the magnetic layer is obtained.

The magnetic recording medium W is then continuously wound into a coil shape by the winding means 3.

The roll WR of the magnetic recording medium W wound into a coil as described above is transported to the next magnetic sheet processing step 4, and is first unwound by the unwinding means 5. The longitudinal cutting means 6, which is equipped with a slitter consisting of a plurality of sets of rotatable upper and lower blades arranged in the width direction of the recording medium W, cuts a narrow strip having a width of 10 crfL to 50 crI'L depending on the purpose of use. The recording medium W1 is cut into widths of 10 cIn to 50 cIrL, and then cut into widths of 10 cIn to 50 cIrL by the horizontal cutting means 7 equipped with a cutter consisting of a pair of upper and lower blades arranged in the width direction of the narrow width recording medium W1.
It is cut into a square magnetic sheet (W2) having a length of .

Next, the square magnetic sheet W2 is cut into an inner diameter of 0.5 cI by the circular punching means 8 consisting of a punch and a die.
IL~3cIrL1 outer diameter is 10cIrL~50cIIL
Punch it out to obtain a donut-shaped magnetic sheet (W3).

The surface of the donut-shaped magnetic layer W3 obtained as described above is superfinished and the surface of the magnetic layer is roughened in the After inserting the magnetic layer so that Hmax is 0.5μ or less, and smoothing by calendering, the magnetic layer is inserted so that the surface roughness in the Y direction of the magnetic layer is 0.5μ or less by Hmax. Calendar and smooth.

As mentioned above, each surface roughness in the X and Y directions is Hmax
When the donut-shaped magnetic seam) W3 of 0.5 μ or less and the difference in each Hmax of 0.1 tt or less is obtained, the calendaring in the X and Y directions by the surface finishing means 9 is completed.

In order to obtain a surface roughness of 0.5μ or less at Hmax, the surface finishing means 9 has a calendering linear pressure of at most 50 per width of the donut-shaped magnetic sheet W3.
It is desirable that the weight can be set up to 0 kg.

Furthermore, in order to further reduce the difference in surface roughness in each calendering direction, it is also possible to perform calendering by the surface finishing means 9 not only in two directions as described above but also in multiple directions.

Further, similar finishing means may be successively provided on the downstream side of the surface finishing means 9, or the magnetic layer forming step 1 may be
It is also possible to arrange finishing means exclusively for the X direction between the drying means 2 and the winding means 3 in order to improve the working efficiency of the magnetic sheet processing steps.

Furthermore, even if the surface finishing means 9 is disposed upstream of the circular punching means 8 and the surface of the magnetic layer of the square magnetic sheet W2 is calendered in the same manner as the donut-shaped magnetic sheet W3, the magnetic sheet is It does not impair performance in any way.

- Also, in another embodiment, instead of the surface finishing means 9, the surface of the magnetic layer of the square magnetic layer) W2 or the donut-shaped magnetic layer W3 is applied to the upper surface of a highly precisely finished optical plane glass plate. It is possible to produce a magnetic sheet having the above-mentioned surface roughness by fixing the magnetic sheet and polishing it using a surface finishing means equipped with a lapping machine.

The manufacturing method of the present invention described above has the following novel effects.

(1) The surface finishing means 9 roughens the surface of the magnetic layer of the magnetic sheet in at least two directions to a level of Hma.
x is 0.5μ or less and the difference therebetween is 0.1μ or less, so that the helad touch of the surface of the magnetic layer to the magnetic head of the VSR is smoother and stabilized, and furthermore, It has become possible to significantly reduce output fluctuations during one rotation of the magnetic sheet due to surface roughness.

(2) Since the surface finishing means 9 calendars the surface of the magnetic layer of the magnetic sheet in at least two directions, the curling of the magnetic sheet is corrected, and as a result, the helad touch of the magnetic sheet is further stabilized. is now possible.

(3) The effects of 1) and (2) above make it possible to significantly extend the life of the magnetic sheet.

The above effects will be clarified by examples.

Example 1 A magnetic coating liquid having the following composition was coated on one side of a support made of a polyethylene terephthalate film with a thickness of 22μ by a spray coating method to form a magnetic layer with a thickness of 6μ.

(Magnetic coating liquid composition) (Parts by weight) r-Fe20
3 (size 0.3μX0.1μ) 300 parts vinyl chloride/vinyl acetate copolymer (87/13 average degree of polymerization 300) 30 parts acrylonitri-V-styrene copolymer (74/26 average degree of polymerization 350) 20 parts carbon black ( Chromium oxide (size 0.2μ x 0.3μ) 10 parts Silicone oil 4 parts Methyl ethyl ketone 720 parts After that, a part of the magnetic layer was sampled to make the magnetic layer static. After confirming that the properties, namely coercive force (He) and squareness ratio (SQ) are uniform over the entire surface,
The support was cut into a donut shape with an outer diameter of 19 CIIL to produce 10 magnetic sheets (Al-10).

Next, the magnetic sheet was calendered using two calender rollers with a superfinished metal surface having a diameter of 40 crn and whose surface temperature was maintained at 45°C, according to the combination conditions of calendering direction and calendering pressure shown in Table 1. Rendered.

Next, each magnetic sheet was mounted on a VSR rotating at 1800 rpm with the magnetic layer surface facing upward, and the center of the magnetic head was set at a position 4.5 m (4.5 m) from the center of the magnetic sheet.
When a Hz signal was recorded in each magnetic layer and reproduced, the output fluctuation, sheet life, flying characteristics, etc. of each magnetic sheet were compared, and the results shown in Table H were obtained.

Example 2 A magnetic coating liquid having the composition shown below was applied to one side of a support made of a polyethylene terephthalate film having a thickness of 36μ by a spray coating method to form a magnetic layer having a thickness of 8μ.

(Magnetic coating liquid composition) (Parts by weight) γ-Fe2O
3 (size 0.4μX0.1μ) 300 parts vinyl chloride/vinyl acetate copolymer (87/13 average degree of polymerization 300) 35-tone μ acrylonitrile/styrene copolymer.

o sound 74/26 average degree of polymerization 350) carbon fiber (size 0.1μX □ o sound 50
．． 2μ) Silicone oil 2 parts Chromium oxide (size 0.2μ x 0.3μ) 15 parts Methyl ethyl ketone 700 parts After that, check the static characteristics of the magnetic layer in the same way as in Example ①, cut it into a donut shape and make 10 magnetic layers. C)' (/l611-20) was prepared, and calendered using a calender roller in the same manner as in Example (2) according to the combination conditions of calendering direction and calendering pressure shown in Table (2).

:Next, in the same way as Example ■, attach it to the VSR, record,
Perform playback to check the output fluctuations of each magnetic sheet, sheet life,
When the flying characteristics etc. were compared, the results shown in Table 1 were obtained.

From the results of Examples I and H detailed above, it is clear that unless the surface roughness of either one is 0.5 μ or less at Hmax, a sheet output (+1 dB or more) suitable for high-density recording cannot be obtained, and furthermore, output fluctuations and Considering the sheet life and flying characteristics, the surface roughness is Hma in at least two directions.
x is 0.5μ or less and the difference in Hmax in two directions is 0.1
It was confirmed that it is desirable to make the thickness less than μ, and it is of course effective in improving sheet output.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet diagram of a magnetic sheet manufacturing process showing one embodiment of the present invention. 1 is a magnetic layer forming step, 4 is a magnetic sheet processing step, and 9 is a surface finishing means.

Claims (1)

[Claims] 1. In the method for manufacturing a flexible magnetic sheet, the surface of the magnetic layer of the magnetic sheet is made such that each surface roughness in at least two directions has a maximum height of 0.5 μm or less, and each maximum height in the two directions has a maximum height of 0.5 μm or less. The difference is 0.1
A method for manufacturing a magnetic sheet, characterized in that the surface of the magnetic layer of the magnetic sheet is finished by calendering the magnetic sheet in at least two directions so that the magnetic layer is less than μ.