JPH0615207A - Elastic roll, its production and producing device therefor - Google Patents

Abstract

PURPOSE:To improve the wetting properties and abrasion resistance of an elastic roll by roughing the surface of a fluororesin coat in a satin finish pattern when the elastic roll for a gravure coating device with a fluororesin-coated surface is used. CONSTITUTION:A furnisher roll 13 used for a device to apply a magnetic paint to a magnetically recorded medium such as magnetic tape has a coat 18 of fluororesin such as solvent-resistant FEP (a copolymer of ethylene tetrafluoride and propylene hexafluoride) formed on the surface of a rubber elastic product provided on a core material. The surface of the fluororesin coat 18 is uniformly roughed in a satin finish pattern by ejecting a grinding powder dispersed liquid to the surface of this elastic roll 13. This surface processing is performed by a processing device, equipped with a nozzle 36 for ejecting the dispersed liquid and a nozzle 37 for ejecting an air for cleaning and drying, as a jet head 30, which is movable in the longitudinal direction of the elastic roll 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic roll (for example, a rubber roll used as a finisher roll for supplying a coating material for a gravure coating device), a method for producing the same, and an apparatus for producing the same.

[0002]

2. Description of the Related Art Generally, in audio tapes and video tapes, a magnetic paint prepared by dispersing and kneading a ferromagnetic powder, a binder, a dispersant, a lubricant, etc. in an organic solvent on a non-magnetic support such as a polyethylene terephthalate film. To form a magnetic layer.

In order to apply such a magnetic coating material onto a non-magnetic support, a gravure coating method has been widely used from the viewpoints of high-speed productivity, easy operation and management, and low production cost. It was

The gravure coating apparatus is, as shown in FIG.
A gravure roll 1 as a transfer body having an uneven cell pattern formed on the surface for transferring the magnetic coating material 12 onto the non-magnetic support 4, and a core for pressing the non-magnetic support 4 onto the gravure roll 1. It comprises a backup roll 2 in which a rubber elastic body 15 is wound around a material 14, and a finisher roll 13 which supplies the magnetic coating material 12 from a nozzle 11 to the concave portion 10 of the gravure roll 1.

Further, this gravure coating apparatus further includes
A doctor blade 7 is provided which regulates the amount of magnetic paint 6 applied, whereby excess paint is collected in the pan 8. Further, the non-magnetic support body 4 coated with the magnetic coating material with a predetermined thickness in the coating portion 9 is guided by the guide roller 3 to the next step (for example, the drying step).

By the way, the above-mentioned finisher roll 13 serves as a supply or filling roll for supplying the magnetic coating onto the gravure roll 1, and imparts solvent resistance to the surface of the rubber elastic body 17 provided on the core material 16. Therefore, it has a structure in which a coating 18 of a fluororesin such as FEP (tetrafluoroethylene-6 fluoropropylene copolymer) or PFA (perfluoro rubber) is formed.

The finisher roll 13 has a good affinity with the magnetic paint (hereinafter referred to as "wetting property") (that is, the transfer liquid can be sufficiently filled without splashing on the transfer body and is even). It is required to have the ability to be transferred to. For this reason, surface treatment is carried out in order to improve the wetting property of the surface of the fluororesin coating and to perform uniform filling and the like, but as a general processing method, a polishing method, a dissolution method, etc. are known. . Among them, polishing method and dissolution method are
It is used as a simple and inexpensive device.

In the polishing method, however, as shown in FIG. 5 (A), a feed mark (hereinafter referred to as a feed mark) formed by grinding with a grindstone has a spiral pattern, or shavings of fluororesin are grindstones. And the scratches (hereinafter referred to as "scratches") are apt to occur, causing unevenness in filling of the coating liquid at the portion 19, which often causes unevenness in the coating. It is considered that this is because the surface tension (that is, wetting property) of the coating liquid due to the marks or the like is uneven on the roll surface.

On the other hand, in the dissolution method, the perfluoro portion on the surface of the fluororesin coating is dissolved with a sodium metal solution, and the carbonized portion improves the wettability. However, since an organic solvent (trichlene, benzene, methyl ethyl ketone, etc.) is used in the washing process before dissolution, there is a problem that an odor is generated, and naphthalene (mixed component in metallic Na) and tetrahydrofuran (solvent) are fluorine. It reacts with the perfluoro portion of the resin film, causing a problem that naphthalene odor is strongly generated. Moreover, since the reaction speed is fast, it is necessary to perform the treatment quickly in a short time of 5 to 10 seconds. As shown in FIG. 5B, the treatment unevenness 20 is likely to occur, and further, the post-treatment cleaning of the treated surface is performed. Alcohol is used, but if it is insufficient, unevenness is likely to occur, and considerable skill is required to prevent it.

[0010]

In any case, since the conventional technique has many problems in uniformly filling or transferring the coating liquid, the present invention uses a structure and a method completely different from the polishing method and the dissolving method. It is an object of the present invention to provide a roll having a uniform and good wettability and the like and excellent durability, and a manufacturing method and a manufacturing apparatus therefor.

[0011]

That is, according to the present invention, in an elastic roll having a surface of a roll-shaped elastic body provided with a fluororesin film, the surface of the fluororesin film is formed into a satin-like uniform rough surface. The present invention relates to an elastic roll characterized in that

The present invention also provides a method for producing this elastic roll, in which a fluororesin coating is formed on the surface of a roll-shaped elastic body, and a dispersion of abrasive powder is sprayed onto the fluororesin coating. This provides a method for manufacturing an elastic roll, which finishes the surface of the fluororesin coating film into a satin-finished and uniformly rough surface.

Further, according to the present invention, as an apparatus for carrying out this manufacturing method, a supporting means for supporting an elastic roll having a fluororesin coating on the surface of a roll-shaped elastic body, and the fluororesin coating in this supporting state are provided. The present invention also provides an elastic roll manufacturing apparatus having a spraying means for spraying a dispersion of abrasive powder on the surface of the elastic roll.

In this manufacturing apparatus, it is preferable that the jetting means comprises a jetting nozzle movable in the lengthwise direction of the elastic roll, and the jetting nozzle of the drying air is arranged in parallel with this jetting nozzle.

[0015]

EXAMPLES Examples of the present invention will be described below. 1 to 6 show an embodiment in which the present invention is applied to a finisher roll used in a device for applying a magnetic paint to a magnetic recording medium such as a magnetic tape.

The finisher roll 33 used in this embodiment
Is the same as described in FIG. 7, on the surface of the rubber elastic body 17 such as ethylene-propylene copolymer provided on the core material 16,
It has a structure in which a coating film 18 of a fluororesin such as FEP (tetrafluoroethylene-6 fluoropropylene copolymer) or PFA (perfluoro rubber) is formed to impart solvent resistance. In order to make the surface of 18 a uniform roughened surface and improve wettability, the surface is roughened by spraying a dispersion of an abrasive powder as described below.

As the dispersion liquid of the abrasive powder that can be used for the roughening, fine particles such as glass beads and white alumina which is a raw material of the grindstone are used, and the particle size display is # 18.
It is preferable to use a dispersion liquid in which 0 to # 250 (the number is selected depending on the type of coating liquid) is mixed with water. For example, a dispersion liquid obtained by mixing and dispersing 15 to 25 parts by weight (for example, 20 parts by weight) of abrasive powder with respect to 100 parts by weight of water can be used.

The particle size of the fine particle powder used here is preferably within the above range, but if it is too small, the polishing power will decrease,
On the other hand, if it is too large, the jetting state of the liquid deteriorates. Also, the mixing amount thereof is preferably within the above range for the same reason. Water is suitable as the dispersion medium, but other media can be used.

Then, as shown in FIG. 1, the jet head 30 is directed in the direction of arrow 31 (parallel to the roll axis) with respect to the fluororesin coating 18 in a state where the finisher roll is rotated at a low speed.
While reciprocating 3 to 5 times, the dispersion liquid 34 from the supply pipe 40 is jetted by the pressure of the air 32 from the supply pipe 39.
Spray as 34 '. As a result, the coating film 18 is uniformly roughened by the above-mentioned dispersion liquid of the abrasive powder, and is finished to a satin-finished rough surface 35 having a uniform roughness of 5 to 10 μm as shown in FIG. 5C.

Since this rough surface finish is performed by spraying an aqueous dispersion of an abrasive powder, remarkable effects as shown in the following (1) to (5) can be obtained.

(1) Since the polishing is performed by spraying a dispersed abrasive in a liquid, the degree of polishing is uniform in terms of location. Therefore, the feed mark ( Since the feed mark) disappears and the shavings of the fluororesin are blown off together with the dispersion liquid, scratches do not occur on the coating.

(2) Since the treatment can be performed only by jetting the above dispersion liquid, the roughness of the coating film 18 finished by the treatment should be sufficiently and surely finished to a desired uniform state by the jetting amount, the head moving speed and the like. However, no skill is required for the work. Therefore, the processed surface is treated with sodium metal (naphthalene + tetrahydrofuran solution)
There is no processing unevenness that could not be avoided by the conventional dissolution method of 1.

(3) In this way, the fluororesin coating film has a uniform and evenly rough surface, has excellent wettability with respect to the coating liquid, and has a uniform surface tension. As a result, it becomes very effective for filling the coating liquid well during use as a finisher roll as shown in FIG. 7 and improving the transferability to improve the coating property. The roughness of the film can be controlled by the above-mentioned jetting conditions according to the coating liquid conditions including the composition of the coating liquid to be transferred.

(4) Moreover, since the rough surface is more uniform than the conventional method by grinding with a grindstone or treatment with metallic sodium, the wear resistance (durability) of the roll is stable, which leads to a longer life.

(5) Furthermore, since the above-mentioned dispersion liquid only uses water as a dispersion medium and does not use a medium such as an organic solvent that is toxic or has a bad odor or may generate a bad odor, it is environmentally friendly. It is advantageous.

As shown in FIG. 1, the jet head 30 of the dispersion liquid has a mode in which the dispersion liquid 34 is jetted from the nozzle 36 by air pressure, and the air 32 alone is jetted from the nozzle 37 after jetting. A valve 38 for switching between a cleaning mode and a drying mode can be provided. This valve can be provided at a position different from the head 30.

Alternatively, as shown in FIG. 2, the head 30 is provided with one nozzle 36, the dispersion liquid 34 'is jetted by air pressure, and the supply pipe 40 for the dispersion liquid 34 is provided with a switching valve to disperse the dispersion liquid 34'. It may be made possible to select either the supply or the stop of the supply.

FIG. 3 schematically shows an apparatus for processing rolls by jetting a dispersion liquid. According to this processing device, the finisher roll 13 to be processed is rotatably supported on the liquid storage pan 41 with the hood 51 in the base portion 42, and the drive synchronizing pulley 43 arranged at one end of the rotation shaft. Is supplied to the synchro pulley 46 of the driving force transmitting portion 45 by the belt 44, and the rotational driving force by the motor (not shown) is applied to the roll 13
Have been communicated to.

A wire drive unit 47 for moving the jet head 30 along the roll 13 is provided on one side of the pan 41. As shown in FIG. 4, the wire driving unit 47 has a wire 50 that is wound or unwound by the shafts 48 and 49 at both ends while the head 30 is fixed. The head 30 is configured to be capable of reciprocating in the direction of arrow 31 (however, details of the winding mechanism thereof are not shown).

On the other hand, in order to prepare the above-mentioned dispersion liquid 34, a stirring tank 53 for uniformly mixing the dispersion liquid 34 with a stirrer 52 is arranged in the base portion 42, and is supplied from this stirring tank by a pump 54. tube
The dispersion liquid 34 is led to the above-mentioned head 30 through 40.

The above-mentioned finisher roll can be used, for example, when applying a magnetic paint. FIG. 6 shows an example of a magnetic recording medium (for example, a magnetic tape for video) manufactured by the application. is there. That is,
On one surface of the non-magnetic support 4 such as polyethylene terephthalate, there is a magnetic layer 60 formed by applying a magnetic paint containing magnetic powder, an abrasive, a binder and the like. In addition, a back coat layer 61 mainly composed of non-magnetic powder and a binder may be provided on the other surface as indicated by a chain line.

Next, the finisher rolls are subjected to various surface roughening treatments under the conditions shown in the table below, and the respective coating liquids are filled and transferred (applied) as shown in FIG. 7 using the respective finisher rolls. The specific result of the above will be explained.

First, the processing of the finisher roll is performed in the following 3
I went the street way. Polishing method: Using a diamond grindstone (conventional method) Dissolving method: Using a metal sodium solution (conventional method) Dispersion liquid injection method: Dispersion liquid is injected by air pressure under roll rotation,
The nozzle reciprocates, and after spraying it is cleaned with air spray and dried (Fig. 3
The method according to the present invention shown in

The coating conditions of the coating liquid were as follows, and the following magnetic coating material for the magnetic layer and non-magnetic coating material for the back coating layer were applied. Coating speed on non-magnetic support (polyester film): 350 m / min Gravure roll: With 45 ° helical cell pattern (with doctor blade) Circumferential speed 350 m / min Finisher roll: Shown in the table below. Backup roll: Rubber roll

Magnetic paint: Magnetic powder: Co-adhered γ-Fe ₂ O ₃ powder 100 parts by weight Binder: Salt-vinyl acetate copolymer (VAGH manufactured by UCC) 10 parts by weight Polyurethane (N-2304 manufactured by Nippon Polyurethane Co., Ltd.) ) 10 parts by weight Dispersant: lecithin 1 part by weight Abrasive: chromium oxide 2 parts by weight Carbon: Vulcan XC-72 (manufactured by Cabot) 3 parts by weight Solvent: cyclohexanone proper amount methyl ethyl ketone proper amount toluene proper amount

Non-magnetic coating material: Non-magnetic powder: 40 parts by weight of carbon black Binder: 50 parts by weight of salt-vinyl acetate copolymer (VAGH manufactured by UCC) Dispersant: 1 part by weight of lecithin Solvent: Suitable amount of cyclohexanone Methyl ethyl ketone Suitable Amount Toluene Amount

Then, the viscosity of the magnetic paint is 3000 to 3500 cps.
The viscosity of the non-magnetic paint was 50 to 80 cps, and the non-magnetic support was applied on the non-magnetic support so that the former had a dry thickness of about 4.0 μm and the latter had a dry thickness of about 0.7 μm. Then, the filling state and the coating state of the coating liquid from the finisher roll to the gravure roll were observed, and the results shown in the following table were obtained.

However, in the evaluation, the average results observed for three samples when operated three times under the same conditions were expressed as follows. ◯: Good condition without unevenness Δ: Condition requiring adjustment X: Condition with unevenness and problems

[0039]

According to this result, the use of the finisher roll obtained by roughening the fluororesin coating according to the present invention improves the filling property of the coating liquid as compared with those obtained by other processing methods, and It can be seen that the coating state of the coating liquid is also improved.
In particular, as can be seen in Samples 2 and 3 of the present invention, it can be seen that the results are remarkably improved by processing by spraying the abrasive dispersion so that the surface roughness becomes Rz 4 or more.

Although the embodiments of the present invention have been described above, the above embodiments can be further modified based on the technical idea of the present invention.

For example, the structure and material of the above-mentioned finisher roll can be variously changed, and the paint transfer system is not limited to the gravure roll system.

Further, the composition of the dispersion liquid used for roughening the surface of the fluorine resin coating of the finisher roll, especially the type and particle size of the abrasive and the type of dispersion medium, may be changed, and the jetting method of the dispersion liquid and the head. The driving method and the like may be changed.

The present invention is not limited to the above-mentioned finisher roll, but can be widely applied to other elastic rolls. For example, by performing the process of the present invention on a fluororesin-coated roll used in a toner fixing device in an electrophotographic copying machine or the like, instead of the usual roughening treatment with metallic sodium, odor, unevenness, etc. The current problems that cannot be avoided can be effectively resolved.

[0045]

As described above, according to the present invention, a dispersion of abrasive powder is sprayed onto the fluororesin coating formed on the surface of the roll-shaped elastic body, whereby the surface of the fluororesin coating is matte-like. Since it is finished with a uniform rough surface with,
By dispersing in liquid and polishing by spraying an abrasive, the degree of polishing becomes uniform in terms of location, the feed marks (feed marks) generated by the conventional polishing method with a grindstone are eliminated, and fluorine is eliminated. Since the resin shavings are blown off together with the dispersion liquid, scratches do not occur on the coating.

Further, since the treatment can be carried out only by jetting the dispersion liquid, the roughness of the coating film finished by the treatment can be sufficiently and surely finished to a desired uniform state by the jetting amount, the head moving speed and the like. Moreover, no skill is required for the work. Therefore, the processed surface is treated with sodium metal (naphthalene + tetrahydrofuran solution)
There is no processing unevenness that could not be avoided by the conventional dissolution method of 1.

As a result, the fluororesin coating film has a uniform and evenly rough surface and has excellent wettability with respect to the coating liquid and the like, the surface tension of the coating liquid becomes uniform, and the filling of the coating liquid can be performed well. However, it is extremely effective in improving the transfer property by improving the transfer property. The roughness of the film can be controlled by the above-mentioned jetting conditions according to the coating liquid conditions including the composition of the coating liquid to be transferred.

In addition, since the rough surface is more uniform than the conventional method by grinding with a grindstone or treatment with metallic sodium, the abrasion resistance (durability) of the roll is stable and the life is improved.

Further, since the above dispersion liquid uses only water or the like as a dispersion medium and does not use a medium such as an organic solvent, which is toxic, has a bad odor, or can generate a bad odor,
It is also environmentally advantageous.

[Brief description of drawings]

FIG. 1 is a schematic view of a dispersion jet head that can be used in the present invention.

FIG. 2 is a schematic view of another dispersion jet head that can be used in the present invention.

FIG. 3 is a partially cutaway schematic perspective view of an apparatus for processing a roll by spraying a dispersion liquid according to an embodiment of the present invention.

FIG. 4 is a perspective view of a dispersion jet head and its moving means of the processing apparatus.

5A and 5B are front views schematically showing the surface of a finisher roll processed by a conventional method, and FIG. 5C is a schematic view of the surface of a finisher roll processed by the method of the present invention. FIG.

FIG. 6 is a cross-sectional view of a part of a magnetic recording medium manufactured using the above-mentioned finisher roll.

FIG. 7 is a schematic diagram showing a configuration example of a conventional gravure coating device.

[Explanation of symbols]

 1 ... Gravure roll 2 ... Backup roll 4 ... Non-magnetic support 12 ... Magnetic paint 13, 33 ... Finisher roll 16 ... Core material 17 ... Elastic body 18 ...・ Fluorocarbon resin coating 19 ・ ・ ・ Feed marks or scratches 20 ・ ・ ・ Processing unevenness 30 ・ ・ ・ Jet head 32 ・ ・ ・ Air 34 ・ ・ ・ Dispersion liquid 34 '・ ・ ・ Jet liquid 35 ・ ・ ・ Uniform rough surface 36, 37 ... Injection nozzle 38 ... Switching valve 43, 46 ... Synchronous pulley 44 ... Belt 45 ... Driving force transmission section 50 ... Wire

Claims (4)

[Claims] 1. An elastic roll having a fluororesin coating on the surface of a roll-shaped elastic body, wherein the fluororesin coating has a satin-finished and uniformly rough surface. . 2. A fluororesin coating is formed on the surface of the roll-shaped elastic body, and then a dispersion liquid of abrasive powder is sprayed onto the fluororesin coating, whereby the fluororesin coating has a satin-finished surface. A method for manufacturing an elastic roll that finishes to a rough surface. 3. A support means for supporting an elastic roll having a fluororesin coating formed on the surface of a roll-shaped elastic body, and an injection for ejecting a dispersion liquid of an abrasive powder onto the surface of the fluororesin coating in this supported state. An apparatus for manufacturing an elastic roll, comprising: 4. The manufacturing apparatus according to claim 3, wherein the jetting means comprises a jetting nozzle movable in the length direction of the elastic roll, and the jetting nozzle of the drying air is arranged in parallel with the jetting nozzle.