JP2000237659A - Gravure coating apparatus and production thereof and method for producing magnetic recording medium using gravure coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make certainly formable a uniform and equal coating film smoothly and sufficiently thinly even if a sheet to be coated is reduced in thickness. SOLUTION: In the gravure coating apparatus, a gravure roll 1 and a backup roll 2 holds a sheet 3 to be coated therebetween to rotate to coat the same with a coating soln. 4. In this case, the backup roll 2 has a core body 21 having a cylindrical peripheral surface and the elastic layer 22 applied and formed at least over the entire periphery of the contact part with the sheet to be coated of the core body 21. Especially, the elastic layer 22 is constituted by once winding an elastic rubber sheet around the entire pheriphery of the core body in an annularly closely bonded state and abutting both end surfaces of the winding start and final ends thereof mutually so as to form one annularly wound elastic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a gravure coating apparatus and a method for manufacturing the same, and a method for manufacturing a magnetic recording medium using the gravure coating apparatus.

[0002]

2. Description of the Related Art In the production of magnetic recording media such as ordinary audio tapes and video tapes, a magnetic layer is formed by applying a magnetic material paint on a non-magnetic support such as a polyethylene terephthalate film. By applying a paint, there is a case where an operation of forming a back layer is performed for the purpose of improving running properties, preventing static electricity from being charged, or preventing irregular winding.

Conventionally, the work of forming a coating film is performed by a gravure coating method, so that productivity is high.
It is widely used because it is easy to manage and the production cost is low.

[0004] A gravure coating apparatus for carrying out this gravure coating method is, for example, a gravure roll 1 comprising a metal roll having fine irregularities, so-called cell patterns 1a, engraved on its peripheral surface as shown in a schematic sectional view of FIG. And a backup roll 2 which rolls by sandwiching a non-magnetic support constituting a long sheet-shaped coated sheet 3, for example, a non-magnetic support constituting a magnetic recording medium, with the gravure roll 1. On the other hand, a paint storage tank 5 containing the target paint 4 is provided,
A part of the peripheral surface of the gravure roll 1 is immersed in the paint 4, and according to the rotation of the gravure roll 1,
The paint 4 adhered to the peripheral surface is transferred and applied to the sheet 3 to be applied by rolling contact with the gravure roll 1 and pressing from the back by the backup roll 2,
In this way, a coating film in which the coating material 4 is applied to the coated sheet 3, for example, a magnetic layer or a back layer is formed.

A doctor blade 6 is arranged above the liquid level of the paint 4 in the paint containing layer 5, and its free end is brought into contact with the rotating peripheral surface of the gravure roll 1. Excessive paint adhered to the peripheral surface is scraped off, so that the amount of paint on the peripheral surface of the gravure roll 1 is always kept constant.

In such a gravure coating apparatus, in order to uniformly apply the coating material to the sheet 3 to be coated, the back-up roll 2 may press the sheet 3 from the back surface uniformly. is necessary. The backup roll 2 is generally configured such that a peripheral surface of a metal core 21 having a cylindrical peripheral surface is covered with an elastic layer 22.

[0007] The backup roll 2 is required to have solvent resistance to the solvent of the paint, for example, methyl ethyl ketone, cyclohesanone, toluene and the like.
Generally, it is made of synthetic rubber such as ethylene propylene rubber and heat vulcanized silicone rubber. By the way, since this ethylene propylene rubber and heat vulcanization type silicone rubber cannot be injection molded,
To form an elastic rubber layer coated on the core 21 as the elastic layer 22 with these rubbers, unvulcanized ethylene propylene rubber is formed into a sheet having a thickness of, for example, 1.0 mm to 4.0 mm. The sheet is formed into a perfect cylindrical cylindrical metal core 12.
A method is adopted in which the film is spirally wound, vulcanized, and then its peripheral surface is polished into a cylindrical surface.

However, in the coating film formed by the gravure coating apparatus using the backup roll manufactured as described above, streak-like transfer unevenness or periodic transfer unevenness due to distortion unevenness is likely to occur. This occurs because the pressure by the backup roll is not uniform over the entire peripheral surface. The cause is that the edge at the beginning of winding of the wound rubber sheet, that is, the discontinuous portion exists in the lower layer on the core body 21 and is located between the second layer sheet wound on the edge. Since the uniformity is impaired for the entire circumference due to the generation of the gap, if vulcanization molding is performed in this state,
A step is generated on the peripheral surface, and even if a cylindrical surface is polished after vulcanization, a small step is generated or distortion remains, and when gravure coating is performed, uniform pressing is performed over the entire circumference. Is not done. This phenomenon also occurs at the winding end edge of the wound rubber sheet.

As a method of solving such a problem, a predetermined hardness, that is, 55 to 60 degrees with a C-type hardness tester of SRS0101 quasi standard, having a thickness of 1.0 mm An unvulcanized rubber sheet of, for example, ethylene propylene or a heat vulcanized silicone rubber sheet having a thickness of 0.8 mm to 1.0 mm is wound at the winding start end where the step is generated. A method has been proposed in which a similar unvulcanized sheet is filled in a wedge shape to reduce this step, and at the end of winding, a similar wedge treatment is performed, followed by vulcanization molding and polishing. (For example, see Japanese Patent Application Laid-Open No. 5-208155).

As another method, the peripheral surface of the core is
For example, width 20 mm to 40 mm, thickness 1.0 to 4.0 mm
A method has also been proposed in which the unvulcanized rubber ribbon is spirally wound so as to be shifted in the axial direction of the core body in a plane, and the wound layers are stacked in a multilayered manner to obtain a required thickness.

However, in recent years, for example, a magnetic recording medium has been required to be thinner, and accordingly, a non-magnetic support constituting the magnetic recording medium has been made thinner. In this way, when the nonmagnetic support of the sheet to be coated in the gravure coating is thinned, on the travel of the nonmagnetic support in the gravure coating apparatus, at the time when it enters under the backup roll and at the time when it separates therefrom, Depending on the surface condition of the backup roll, peeling wrinkles due to sticking of the non-magnetic support to the backup roll and transfer unevenness are likely to occur.

With respect to such thinning of the non-magnetic support, that is, thinning of the sheet to be coated, each of the backup rolls described above sufficiently generates wrinkles on the sheet to be coated and uneven transfer of paint by gravure coating. Can no longer be avoided. For example, if the thickness of the non-magnetic support is
When the thickness is 6.0 μm or less, or when the thickness of the coating film, for example, the magnetic layer is 1.0 μm or less, distortion remains in the wedge-filled portion by the above-described wedge-filling method, and the above-described ribbon Even in the case of a spiral winding in a shape, in a multilayer wound state, the overlapping of the ribbons causes undulation due to fine irregularities in a network as a whole, thereby generating wrinkles on the non-magnetic support and gravure There is a problem in sufficiently avoiding uneven transfer of the paint due to application.

In addition, during the gravure coating operation, dust and the like adhere to the backup roll from the sheet to be coated, such as the non-magnetic support, and become contaminated. Therefore, there is a phenomenon that the transfer is affected. This, along with the thinning described above,
The influence becomes more remarkable, and the quality of the product obtained by the gravure coating is reduced.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thinner coating sheet and a thinner coating film.
A gravure coating apparatus capable of forming a uniform and uniform coating film smoothly and sufficiently thinly, a method of manufacturing the same, and a magnetic recording medium having excellent magnetic properties with a good yield. It is another object of the present invention to provide a method for manufacturing a magnetic recording medium that can achieve the above.

[0015]

The gravure coating apparatus according to the present invention comprises a gravure roll and a backup roll,
What is claimed is: 1. A gravure coating apparatus which rolls a sheet to be coated and applies a coating to the sheet to be coated, the backup roll comprising: a core having a cylindrical peripheral surface; At least the elastic layer adhered and formed over the entire periphery of the contact portion with the coated sheet. In particular, the elastic layer is elastically formed over the entire periphery of the above-described core. The rubber sheet is tightly wound in a ring only one round,
It has a structure in which one or more annularly wound elastic layers are annularly wound so that both end surfaces of the winding start end and the terminal end abut against each other.

Further, in the method of manufacturing a gravure coating apparatus according to the present invention, in the process of manufacturing the backup roll, the elastic rubber sheet is provided over at least the entire circumference of the contact portion of the core having a cylindrical peripheral surface with the sheet to be coated. Forming one or more annularly wound elastic layers which are annularly wound such that the winding start end and the end surface of the winding are in abutment with each other only in one round. A step of heating and pressing the elastic layer and a step of processing and finishing the surface of the annular elastic layer are employed.

In the method of manufacturing a magnetic recording medium according to the present invention, a necessary coating film is formed on a non-magnetic support using the gravure coating apparatus according to the present invention. .

According to the gravure coating apparatus of the present invention described above, the backup roll has a configuration in which an elastic rubber sheet is annularly wound on a core, so that high roundness can be achieved. Therefore, according to the gravure coating apparatus having this configuration, excellent gravure coating can be performed.

Further, according to the method of manufacturing a gravure coating apparatus according to the present invention, since a method is employed in which an elastic rubber sheet is annularly wound on a core body, generation of a step is effectively avoided, and The finishing can be performed extremely easily on a superior cylindrical surface, and therefore, a backup roll having high roundness can be produced.

In the method of manufacturing a magnetic recording medium according to the present invention, a gravure coating apparatus having a backup roll having excellent roundness according to the present invention is used to form a thin film such as a magnetic layer and a back layer. Can be manufactured uniformly and therefore with high reliability and magnetic and electrical properties.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment of gravure coating apparatus]
One embodiment of the gravure coating apparatus according to the present invention can have a configuration schematically shown in FIG. 1 described above, for example. However, the device of the present invention is not limited to this example. Also in this example, as described above, the gravure roll 1 made of a metal roll made of, for example, iron (Fe) having a high hardness in which fine irregularities, so-called cell patterns 1a, formed by, for example, spiral cutting having a sawtooth cross section are engraved on the peripheral surface.
And a backup roll 2 that rolls while sandwiching the long sheet-shaped coated sheet 3 with the gravure roll 1.

On the other hand, there is provided a paint storage tank 5 in which the target paint 4 is stored. A part of the peripheral surface of the gravure roll 1 is immersed in the paint 4 so that the gravure roll 1 rotates. Accordingly, the coating material 4 is filled in the fine irregularities on the peripheral surface, that is, the cells, and the rotation of the gravure roll 1 causes the coating material 4 to be brought into contact with the gravure roll 1 of the sheet 3 to be coated, that is, to the coating portion. Sent and applied sheet 3
Then, the paint 4 is transferred. That is, coating is performed on the sheet 3 to be coated, and a coating film, for example, a magnetic layer or a back layer is formed on the sheet 3 to be coated.

A doctor blade 6 is disposed above the liquid level of the paint 4 in the paint containing layer 5. The doctor blade 6 is made of, for example, a rectangular metal plate or a plastic plate, one end of which is fixed, and the free end of which is in contact with the rotating peripheral surface of the gravure roll 1. Excessive paint filled in a large amount with a surface tension in the cell is scraped off, and the amount of paint on the peripheral surface of the gravure roll 1 is constantly reduced.
The amount of application to the ink is always regulated to be constant.

The sheet 3 to be coated is a non-magnetic support made of, for example, a polyester film constituting a magnetic recording medium.
And between the backup roll 2 and further guided by the guide roller 32, not shown, for example, the following work unit, for example, other similar gravure coating device,
Alternatively, it is sent to a cutting section or the like that cuts to a required width.

In the gravure coating apparatus described above, the configuration of the backup roll 2 is such that the cylindrical peripheral surface made of a metal cylinder or metal cylinder made of conductive material such as iron (Fe) or SUS (ie, stainless steel) is used. The elastic layer 22 is applied to the core 21 having the elastic layer 22 over at least the entire circumference of the contact portion of the core 21 with the above-mentioned coated sheet 3. 2A to 2C each show a schematic cross-sectional view of a backup roll of the gravure coating apparatus according to the present invention, but the present invention is not limited to this example. As shown in FIGS. 2A to 2C, the backup roll 2 in the apparatus of the present invention is configured such that the elastic rubber sheet is tightly wound around the entire circumference of the core body 21 in one round only, and the winding start and end of the winding are started. It has one or more annularly wound elastic layers 23 which are annularly wound in abutment with each other as shown by the plane a at both end surfaces.

In the example of FIG. 2A, the elastic layer 22 is constituted by a single-layer annular wound elastic layer 23 made of an elastic rubber sheet. In the example of FIG. 2B, a similar annular wound elastic layer 23 is formed.
In this case, the elastic layer 22 is formed by further applying a coating elastic rubber layer 24 thereon. In the example of FIG. 2C,
In this case, two or more annular wound elastic layers 23 are stacked, and the above-described coated elastic rubber layer 24 is further formed thereon to form the elastic layer 22.

FIG. 2A shows a case where the annular wound elastic layer 23 is wound into a single layer.
It is also possible to laminate more than layers. 2B and 2C show the case where the annular wound elastic layer 23 has a single-layer structure and a two-layer structure, but may have three or more layers. When two or more annularly wound elastic layers 23 are laminated in this manner, the abutting surfaces a of the end faces of the respective annularly wound elastic layers 23 form the same surface as shown in FIG. 2C. Or different planes.

The elastic rubber sheet constituting the annular wound elastic layer 23 is, for example, a heat-curable silicone rubber sheet having excellent solvent resistance to organic solvents such as methyl ethyl ketone, cyclohexanone, and toluene, or a heat-curable silicone rubber sheet. It can be constituted by a sulfur type ethylene propylene rubber sheet.

In this case, the thickness of the elastic rubber sheet is selected to be 1.0 mm to 4.0 mm. If the thickness is less than 1.0 mm, there is a problem in the reliability and elasticity of the sheet. If the thickness is more than 4.0 mm, the thickness of the sheet becomes uneven, and the sheet is stuck at the abutting portions at both end portions. This is because alignment unevenness is likely to occur, and finally the accuracy of the roundness may deteriorate.

The coated elastic rubber layer 24 can be made of a room temperature vulcanizable silicone rubber. Further, it is desirable that the thickness is selected to be 3.0 mm to 5.0 mm. If the thickness is less than 3.0 mm, sufficient surface properties required for the backup roll 2 may not be obtained, and if the thickness exceeds 5.0 mm, bubbles may be generated.

The surface properties of the backup roll 2, that is, the surface accuracy of the elastic layer 22, and therefore, in the configuration of FIG. 2A, the surface hardness of the annular wound elastic layer 23, and in the configurations of FIGS. The surface accuracy Rz of the layer 24, so-called ten-point average roughness, is selected so that Rz ≦ 10 μm. The selection of Rz is such that, when Rz exceeds 10, the grip of the coated sheet 3 by the backup roll 2 becomes too large, damaging the surface itself or the surface of the coated sheet 3 or inducing running wrinkles. Problem arises.

The elastic layer 22 of the backup roll 2
However, even in the case where the covering elastic rubber layer 24 is applied on the annular wound elastic layer 23, the surface accuracy of the lower annular wound elastic layer 23 affects the surface of the elastic layer 22. Therefore, the accuracy is important. In this case, the surface accuracy Rz of the annular wound elastic layer 23 is similarly set to Rz ≦
It is desirable to select 10 μm.

The deflection accuracy of the backup roll surface from a perfect circle is set to 10 μm or less. This is because, when the thickness exceeds 10 μm, the strain applied to the elastic layer 22 increases, which may cause uneven transfer.

The surface hardness of the backup roll 2
In other words, in the configuration of FIG. 2A, the surface hardness of the elastic layer 22 and, in the configuration of FIG.
In the configurations B and C, the hardness of the coated elastic rubber layer 24 is selected from 75 to 85 degrees using an A-type hardness tester according to JIS JIS 6253. This selection is based on a hardness of 8
If it exceeds 5 degrees, the elasticity becomes poor, so that the pressure-bonding width of the backup roll 2 to the gravure roll 1 is likely to be narrow, and the transfer of the paint from the gravure roll 1 to the sheet 3 to be coated becomes non-uniform. If the angle is less than 75 degrees, the backup roll 2
The contact width with the gravure roll 1 is large, the contact area is large, and the paint pops out. Similarly, the transfer of the paint to the sheet 3 to be coated becomes nonuniform, causing transfer unevenness.

The conductivity of the core rubber 21 and the elastic layer 22, ie, the elastic rubber sheet constituting the annular wound elastic layer 23 and the covering elastic rubber layer 24 are measured by measuring the electric resistance of 500 V megaohms. ^By setting the resistance to ⁶ Ω or less, it is possible to prevent the backup roll 2 from being charged, thereby preventing the sheet 3 to be coated from running unevenly and hindering a smooth transition or generating running wrinkles. I do. Furthermore, in the case where a flammable solvent, for example, a solvent such as methyl ethyl ketone, cyclohexanone, or toluene is used for the paint 4, an accident that is ignited by charging is avoided. The conductivity can be adjusted by adding, for example, an appropriate amount of Ketjen black carbon or the like to the elastic rubber sheet and the coated elastic rubber layer.

[Embodiment of Method for Manufacturing Gravure Coating Apparatus] Next, an embodiment of a method for manufacturing a gravure coating apparatus according to the present invention will be described. However, in this case, the present invention is not limited to this example. In this embodiment, a gravure coating apparatus having the configuration according to the above-described gravure coating apparatus according to the present invention is manufactured.

That is, also in this case, for example, the gravure roll 1 and the backup roll 2 shown in FIG. A method of manufacturing a gravure coating apparatus for performing the following will be described with reference to the process chart of FIG. First, as shown in FIG. 3A, a heat-vulcanized unvulcanized elastic rubber sheet 25 and a core 21 having the above-described configuration are prepared. The elastic rubber sheet 25 is made of a heat-vulcanized silicone rubber, so-called HTV, or ethylene-propylene rubber, so-called EPT, is in an unvulcanized state, is calendered, and has a thickness of 1 as described above. It is formed to have a thickness of 0.0 mm to 4.0 mm.

The unvulcanized elastic rubber sheet 25 is connected to the sheet shown in FIG.
As shown in FIG. 3B, both ends 25a and 25b are wound around the cylindrical peripheral surface of the core body 21 so as to overlap each other. In this state, the both ends 25a and 25b overlapped with each other are shown in FIG. Cutting is performed over the entire thickness along a common cutting plane indicated by a chain line b. In this case, the core 21
Above, the elastic rubber sheet 25 is wound as closely as possible, and the cut surface b is selected to cover the entire width of the elastic rubber sheet 25 and to be an inclined surface, that is, a surface inclined from the radial direction of the core 21. Is desirable.

The elastic rubber sheet 25 cut as described above
Since the length of the elastic rubber sheet 25 is almost equal to the peripheral length of the core body 1, the cut elastic rubber sheet 25 is brought into close contact with the entire circumference of the core body 1 as shown in FIG. This elastic rubber sheet 25 is wound around the entire circumference of the core body 1 to form an annular wound elastic layer 24 having an abutment matching surface a in which both end surfaces of both ends 25a and 25b are abutted and matched. Is done.

Next, the elastically wound elastic rubber sheet 25 is formed into a state in which it is brought into close contact with the peripheral surface of the core body 21, and so-called vulcanization is performed. This vulcanization molding is performed by heating and pressing. For example, elastic rubber sheet 25
By placing the core body 21 having an annular winding in a water pressure pressurized and heated to 150 ° C., the elastic rubber sheet 25 adheres to the peripheral surface of the core body 1 while performing so-called vulcanization by a crosslinking reaction. The formed annular wound elastic layer 23 is formed.

In this manner, a backup roll having a single-structure type elastic layer 22 having a single-layer annular wound elastic layer 23 shown in FIG. 2A is formed.

The annular wound elastic layer 23 is not limited to a single layer, but may have a multilayered structure.
For each layer, an annular winding is performed by the same operation, or a plurality of elastic rubber sheets are laminated, and the above-described winding operation and heat-press molding are performed simultaneously.

As shown in FIGS. 2B and 2C, when the covering elastic rubber layer 24 is formed on the annular winding elastic layer 23 as the elastic layer 22, the annular winding wound on the core 21 is used. The above-described room temperature vulcanization type silicone rubber, for example, is applied to the entire surface of the elastic layer 23 and vulcanized at room temperature. Thus, the elastic layer 22 on which the coated elastic rubber layer 24 is formed can be formed.

[Embodiment of Method for Manufacturing Magnetic Recording Medium] Next, an example of an embodiment of a method for manufacturing a magnetic recording medium according to the present invention will be described, but the present invention is not limited to this example.

Example 1 In this example, a backup roll 2 having a single structure shown in FIG. 2A and having an annular wound elastic layer 23 in which a heat-vulcanized silicone rubber sheet is annularly wound in one layer was formed. In this case, a magnetic layer having a composition shown below was applied to a non-magnetic support using the gravure coating apparatus according to the present invention. Magnetic paint; magnetic powder (metal magnetic powder) 100 parts by weight Binder resin 20 parts by weight Abrasive: Al ₂ O ₃ 3 parts by weight Conductive agent: carbon powder 2 parts by weight Methyl ethyl ketone 100 parts by weight Toluene 100 parts by weight Cyclohexanone 50 parts by weight This paint Was applied to a 4.5 μm-thick polyester film at a running speed of 350 m / min.
It was applied at 0.2 μm and cut into 8 mm to produce a tape-shaped magnetic recording medium.

(Embodiment 2) As in the case of the embodiment 1, although the single structure shown in FIG. 2A is used, in this embodiment,
Using a gravure coating apparatus according to the present invention constituted by a backup roll 2 comprising an annularly wound elastic layer formed by annularly winding an ethylene propylene rubber sheet, a non-magnetic support is coated with a magnetic paint having the above composition to form a magnetic layer. Was formed to produce a magnetic recording medium in the same manner as in Example 1.

(Comparative Example 1) The same as in Example 1 except that a gravure coating apparatus constituted by a backup roll formed by spirally winding the heat-vulcanizable silicone rubber sheet described at the beginning of the related art is used. A magnetic recording medium was produced by the method.

Comparative Example 2 Except for using a gravure coating apparatus constituted by a backup roll formed by winding a heat-vulcanized type ethylene propylene rubber sheet on a core in the conventional spiral shape described at the beginning, A magnetic recording medium was manufactured in the same manner as in Example 1.

(Comparative Example 3) A method similar to that of Example 1 except that a gravure coating device constituted by a backup roll constituted by spirally winding a ribbon made of a heat-vulcanized ethylene propylene rubber as described at the beginning was used. Thus, a magnetic recording medium was manufactured.

Comparative Example 4 A magnetic recording medium was manufactured in the same manner as in Example 1 except that a gravure coating apparatus constituted by a backup roll 2 constituted by applying a room temperature vulcanization type silicone rubber ribbon was used. .

Next, another embodiment of the method for manufacturing a magnetic recording medium according to the present invention will be described with reference to examples. In this case, a magnetic recording medium is manufactured by forming a magnetic layer using a gravure coating apparatus including a backup roll 2 having an elastic layer 22 having a dual structure of an upper layer and a lower layer described in FIG. 2C.

(Embodiment 3) The backup roll 2 of the gravure coating apparatus is formed by forming the lower annular wound elastic layer 23 with a heat vulcanizable silicone rubber sheet, and forming the upper coated elastic rubber layer 24 with the room temperature vulcanized silicone rubber. A magnetic recording medium was manufactured in the same manner as in Example 1 using a gravure coating apparatus having a structure coated with.

(Embodiment 4) The backup roll 2 of the gravure coating apparatus was formed by forming the lower annular wound elastic layer 23 by a heat vulcanizable ethylene propylene rubber sheet, and forming the upper coated elastic rubber layer 24 by room temperature vulcanized silicone. A magnetic recording medium was manufactured in the same manner as in Example 1 using a gravure coating apparatus having a configuration in which rubber was applied.

(Comparative Example 5) A backup roll 2 of a gravure coating apparatus was formed by spirally winding an ethylene propylene rubber sheet as a lower elastic layer, and a heat vulcanization type silicone rubber sheet was formed thereon by an annular winding. Using a gravure coating device with a configuration in which the upper elastic layer is stacked,
A magnetic recording medium was manufactured in the same manner as in Example 1.

(Comparative Example 6) A backup roll of a gravure coating apparatus was formed by spirally winding a heat-vulcanized silicone rubber sheet as a lower elastic layer. A magnetic recording medium was manufactured in the same manner as in Example 1 using a gravure coating apparatus having a configuration in which elastic layers were stacked.

(Comparative Example 7) A backup roll of a gravure coating apparatus was formed by spirally winding an ethylene propylene rubber sheet as a lower elastic layer, and a room temperature vulcanization type silicone rubber ribbon was spirally wound thereon. A magnetic recording medium was manufactured in the same manner as in Example 1 using a gravure coating apparatus having a configuration in which the formed upper elastic layers were stacked.

(Comparative Example 8) A backup roll of a gravure coating apparatus was formed by spirally winding a heat-cured silicone rubber sheet as a lower elastic layer, and a room temperature vulcanizable silicone rubber ribbon was spirally wound thereon. A magnetic recording medium was manufactured in the same manner as in Example 1 using a gravure coating apparatus having a configuration in which the upper elastic layer formed as described above was stacked.

The results of evaluation of the magnetic recording medium thus formed are shown in Tables 1 and 2 together with each sheet thickness, layer thickness and the like.

[0059]

[Table 1]

[0060]

[Table 2]

In Tables 1 and 2, HTV is a heat-curable silicone rubber, EPT is an ethylene propylene rubber, and RTV is a room temperature vulcanizable silicone rubber.

Each of the backup rolls has a conductivity of from 1.0 × 10 ^{4 to} 3.
A rubber material of 0 × 10 ⁴ Ω was used.

The evaluations in Tables 1 and 2 are based on the evaluation of the state of transfer of the magnetic paint to the non-magnetic support, that is, the quality of the transfer unevenness, when the non-magnetic support enters the backup roll, or when the non-magnetic support moves away from the back roll. The evaluation of the quality of the wrinkles due to the sticking phenomenon during running, the releasability, that is, the quality of running, and the quality of observing the adhesion of dust such as dust and contamination adhering to the surface of the backup roll were indicated by ○ and Δ.
These are indicated by marks and crosses.

That is, in the evaluation of transfer unevenness, the mark ○ indicates that there was no transfer unevenness, and the mark △ indicates that transfer unevenness was slightly generated, but not to the extent that it could not withstand use. This is the case where it cannot be used at all.
Regarding the runnability, the mark ○ indicates stable runnability, and the mark Δ indicates that the sticking phenomenon occurs to some extent, but not to the extent that it cannot withstand use. This is a case where wrinkles occur and cannot be put to practical use. In addition, in the case of dust adhesion, the mark ○ indicates that dust adhesion was hardly observed, the mark △ indicates that some occurrence occurred, but it was not enough to endure use, and the mark × indicates dust on the surface of the backup roll. This is the case where it adheres and cannot be put to practical use.

As is clear from Tables 1 and 2,
According to Examples 1 to 4 according to the present invention, the annular wound elastic layer 2
The backing roll has an elastic layer 22 or an annular wound elastic layer 23 as a lower layer and an elastic layer 22 on which a coated elastic rubber layer 24 is formed on the core 21, so that a thin film can be obtained. It can be seen that even when applied to the formation of a magnetic layer of a magnetic recording medium, excellent gravure coating can be performed in terms of transfer unevenness, running properties, and dust adhesion.

On the other hand, in a single-layer structure in which only a liquid silicone rubber for room temperature vulcanization was applied and coated on a core to a predetermined layer thickness as in Comparative Example 4, for example,
Since the coating layer is thick, the liquid silicone causes uneven curing density at the time of normal temperature curing, causing unevenness in hardness. When the backup roll is pressed against the gravure roll, uneven deformation is caused to cause transfer unevenness.

As can be seen from Comparative Example 7, in the case of a coating layer having a silicone rubber RTV for room temperature vulcanization of less than 3.0 mm, a slight step or distortion of the seam in the lower layer slightly affects the transfer. Causes unevenness. Further, when a coating layer having a thickness of 5.1 mm or more is coated as in Comparative Example 8, unevenness in hardness is generated due to the uneven curing density at room temperature, which causes uneven transfer.

That is, according to the gravure coating apparatus of the present invention, the configuration of the backup roll 2 is such that the elastic layer 22 formed on the peripheral surface of the core body 21 has at least the lower elastic layer as an annular winding by annular winding. Elastic layer 23
As a result, the occurrence of a step due to the overlapping of the winding ends can be avoided, and a backup roll with excellent surface properties and high roundness accuracy can be formed. Due to the presence of the wound elastic layer 24, the required elasticity can be imparted to the backup roll.

Accordingly, as described above, when a coating film is formed using the gravure coating apparatus according to the present invention,
The sheet to be coated, in the above-described example, a thinner non-magnetic support,
Even by the thinning of the coating film, it is possible to reliably perform the good running property, therefore, effectively avoid the occurrence of wrinkles,
In addition, the transfer unevenness can be improved, and therefore, a uniform and uniform coating film can be formed. Further, in the case of manufacturing a highly reliable coating by improving the adhesion of dust, and thus manufacturing a magnetic recording medium or the like, The reliability and the yield can be improved, and in the magnetic recording medium, a magnetic recording medium having excellent magnetic characteristics can be obtained with a good yield.

In the method for producing a magnetic recording medium according to the present invention, the composition of the non-magnetic support and the magnetic paint are not limited to those described above. For example, polyethylene terephthalate, polyethylene -2
A polyester resin such as an aromatic polyamide resin film can be used. Examples of the magnetic powder of the magnetic paint include Fe-Co, Fe-Ni, Fe-Co-Ni,
Co-Ni, Fe-Mn-Zn, Fe-Co-Ni-
It is preferable to use metal particles such as P, Fe-Co-Cr-B, which are mainly composed of Fe, Co, and Ni.

As the binder, polymers such as vinylidene chloride, acrylic acid ester, methacrylic acid ester, styrene, butadiene, acrylonitro, or copolymers such as polyurethane resin and polyester resin are used. These are kneaded and dispersed with the ferromagnetic powder to form a magnetic paint.

As the solvent, any of conventionally known solvents can be used, and acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone ketones, ester such as methyl acetate and ethyl acetate, glycol ethers such as glycol dimethyl ether and dioxane can be used. System, aromatic hydrocarbons such as toluene and xylene are used.

Further, as an additive, a dispersant, an internal additive, an abrasive, an antistatic agent, a rust inhibitor and the like may be added.

In the method for manufacturing a magnetic recording medium described above, the gravure coating is performed in forming the magnetic layer. In addition to this, for example, if necessary, a back coat layer, a top coat layer, or the like may be used. In the formation of, gravure coating can be applied using the gravure coating apparatus according to the present invention.

In the gravure coating apparatus, although not shown, the present invention is limited to the above-described example. For example, not only the backup roll but also the nip roll and other impression rolls can be configured as described above with reference to FIG. However, various modifications can be made.

According to the gravure coating apparatus of the present invention described above, the backup roll 2 is configured such that the elastic layer 22 is formed by the annularly wound elastic layer 23 in which the elastic rubber sheet is annularly wound on the core 21. Thereby, high roundness can be obtained, and further, by forming the covering elastic rubber layer 24 thereon, the surface properties and roundness can be further improved. Therefore, according to the gravure coating apparatus according to the present invention, it is possible to configure an excellent gravure coating apparatus which is excellent in running property and in which transfer unevenness is remarkably improved.

Further, according to the method of manufacturing a gravure coating apparatus according to the present invention, as described above, the backup roll 2 is elastically wound by the annular wound elastic layer 23 in which the elastic rubber sheet is annularly wound on the core 21. By forming the structure 22, a high roundness is obtained, so that the occurrence of a step is effectively avoided, and the subsequent processing finish is extremely simple, with excellent high roundness. Therefore, a backup roll having a runout accuracy of 10 μm or less can be reliably and easily manufactured. Therefore, according to the method for manufacturing a gravure coating apparatus of the present invention, an excellent gravure coating apparatus having excellent running properties and significantly improved transfer unevenness can be manufactured with high yield in terms of mass production.

In the method of manufacturing a magnetic recording medium according to the present invention, a gravure coating apparatus having a backup roll having excellent roundness according to the present invention is used to form a thin film such as a magnetic layer and a back layer. Can be manufactured uniformly and therefore with high reliability and magnetic and electrical properties.

[0079]

As described above, in the gravure coating apparatus according to the present invention, the configuration of the backup roll 2 is such that the elastic layer 22 formed on the peripheral surface of the core 21 is formed by at least a circular winding as the lower elastic layer. Since it is constituted by the annular wound elastic layer 23, the occurrence of a step due to the overlapping of the winding ends can be avoided,
A backup roll having excellent surface properties and high roundness accuracy can be configured, and the presence of the annular wound elastic layer 24 can impart required elasticity to the backup roll.

As described above, when the coating film is formed using the gravure coating apparatus according to the present invention,
The sheet to be coated, in the above-described example, a thinner non-magnetic support,
Even by the thinning of the coating film, it is possible to reliably perform the good running property, therefore, effectively avoid the occurrence of wrinkles,
In addition, the transfer unevenness can be improved, and therefore, a uniform and uniform coating film can be formed. Further, in the case of manufacturing a highly reliable coating by improving the adhesion of dust, and thus manufacturing a magnetic recording medium or the like, The reliability and the yield can be improved, and in the magnetic recording medium, a magnetic recording medium having excellent magnetic characteristics can be obtained with a good yield.

Further, in the method of manufacturing the gravure coating apparatus according to the present invention, as described above, the backup roll 2 is made of the elastic layer 22 by the annular wound elastic layer 23 in which the elastic rubber sheet is annularly wound on the core 21. By having a configuration that forms a high degree of roundness, the occurrence of steps is effectively avoided, and the subsequent processing finish is extremely simple, resulting in excellent high roundness, A backup roll having a runout accuracy of 10 μm or less can be reliably and easily manufactured. Therefore, according to the method for manufacturing a gravure coating apparatus of the present invention, an excellent gravure coating apparatus having excellent running properties and significantly improved transfer unevenness can be manufactured with high yield in terms of mass production.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a gravure coating apparatus to which the present invention is applied.

FIGS. 2A to 2C are schematic cross-sectional views of a backup roll of the gravure coating apparatus according to the present invention.

3A to 3C are process diagrams of an example of a method for manufacturing a gravure coating apparatus according to the present invention.

[Explanation of symbols]

1 ... gravure roll, 1a ... cell pattern, 2
... backup roll, 3 ... coated sheet, 4
... paint, 5 ... paint storage tank, 6 ... doctor blade, 21 ... core body, 22 ... elastic layer, 23 ...
.Annular wound elastic layer, 24... Coated elastic rubber layer, 31.
..Guide rollers

Claims (21)

[Claims] 1. A gravure coating apparatus in which a gravure roll and a backup roll roll on a sheet to be coated and apply a paint to the sheet to be coated, wherein the backup roll is a cylinder. A core having a peripheral surface, and an elastic layer formed on at least the entire periphery of the contact portion of the core with the sheet to be coated. One or more annularly wound elastic layers are formed by annularly winding the elastic rubber sheet around the entire circumference in one round only, and the winding start and end of the elastic rubber sheet are abutted against each other. A gravure coating apparatus comprising: 2. The gravure coating apparatus according to claim 1, wherein the elastic layer has a configuration in which a coating elastic rubber layer is formed on the annular wound elastic layer by coating. 3. The gravure coating apparatus according to claim 1, wherein said elastic rubber sheet is made of a heat-vulcanized silicone rubber sheet. 4. The gravure coating apparatus according to claim 1, wherein said elastic rubber sheet is made of a heat-vulcanized tylene propylene rubber sheet. 5. The gravure coating apparatus according to claim 1, wherein the elastic rubber sheet constituting the annular wound elastic layer is selected to have a thickness of 1.0 mm to 4.0 mm. 6. The gravure coating apparatus according to claim 2, wherein said coated elastic rubber layer is made of a room temperature vulcanizable silicone rubber. 7. The coating elastic rubber layer has a thickness of 3.0 m.
3. The gravure coating apparatus according to claim 2, wherein the distance is from m to 5.0 mm. 8. The elastic layer has a surface roughness Rz of Rz ≦ 1.
The gravure coating apparatus according to claim 1, wherein the gravure coating apparatus is selected to be 0 µm. 9. The surface roughness Rz of the annular wound elastic layer is as follows:
3. The gravure coating apparatus according to claim 2, wherein Rz ≦ 10 μm is selected. 10. The gravure coating apparatus according to claim 1, wherein the surface hardness of the elastic layer is selected from 75 to 85 degrees using an A-type hardness tester according to JIS 6253. 11. The gravure coating apparatus according to claim 1, wherein the deflection accuracy of the surface of the backup roll from a perfect circle is 10 μm or less. 12. The gravure coating apparatus according to claim 1, wherein the conductivity of the core and the elastic layer is set to 10 ⁶ Ω or less in a measurement with a 500 V mega Ω measuring instrument. 13. A method of manufacturing a gravure coating apparatus in which a gravure roll and a backup roll roll on a sheet to be coated and apply a paint to the sheet to be coated. In the manufacturing process, only one round of the elastic rubber sheet is tightly wound around the entire periphery of the contact portion of the core body having a cylindrical peripheral surface with the sheet to be coated, and both ends of the winding start end and the end are wound. A step of forming one or more annularly wound elastic layers by annularly winding so that the surfaces abut against each other; a step of forming the annularly wound elastic layer by heat and pressure; And finishing the surface of the gravure coating apparatus. 14. A coated elastic rubber layer is formed by applying a rubber material onto the annular wound elastic layer, forming and finishing the surface after the step of forming the annular wound elastic layer and the step of heating and pressing. 14. The method according to claim 13, further comprising a step.
3. The method for producing a gravure coating apparatus according to claim 1. 15. The gravure coating apparatus according to claim 13, wherein the elastic rubber sheet to be annularly wound on the core body is an unvulcanized heat-vulcanized silicone rubber sheet. Method. 16. The method for producing a gravure coating apparatus according to claim 13, wherein the elastic rubber sheet wound in an annular shape on the core is an unvulcanized heat-vulcanized ethylene propylene rubber sheet. . 17. The method according to claim 14, wherein the rubber material of the coated elastic rubber layer is a room temperature vulcanizable silicone rubber, and the molding is performed by room temperature vulcanization. . 18. A method for producing a magnetic recording medium, comprising a gravure coating step in which a gravure roll and a backup roll are rolled across a non-magnetic sheet to apply a paint to the non-magnetic sheet. The backup roll has a core having a cylindrical peripheral surface, and an elastic layer adhered and formed over at least the entire periphery of a contact portion of the core with the sheet to be coated. An elastic rubber sheet is wound around the entire circumference of the core body only one round in an annular manner, and the winding start end and the end end of the elastic body are abutted with each other to form an annularly wound one or more layers. A method for manufacturing a magnetic recording medium, comprising applying a paint by a gravure coating apparatus having a wound elastic layer to form a coating film. 19. The coating operation of the coating material is performed by a gravure coating device in which the elastic layer has a configuration in which a coating elastic rubber layer is coated on the annular wound elastic layer. The method for manufacturing a magnetic recording medium according to claim 18, wherein: 20. The method according to claim 18, wherein the formation of the coating film is a formation of a magnetic film. 21. The method according to claim 18, wherein the formation of the coating film is a formation of a back layer.