JP2016203119A - Roll coating device and method for manufacturing web formed of coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll coating device which does not allow a cell pattern to remain on a coating surface while suppressing an increase of manufacturing cost and maintenance cost, can apply coating liquid evenly for a web continuously conveyed, can be applied even for a product to which high quality is required and, at the same time, has high quality stability upon continuous production.SOLUTION: A roll coating device transfers coating liquid 2 from a coating roller A which is brought into contact with the coating liquid 2 within a coating liquid tank H and is rotated with respect to a web 1 continuously conveyed and forms a coated film 4 onto the web 1. Therein, the coating roller A has no recessed part for a liquid reservoir on the surface, is provided with pressurizing means B which pressurizes a back surface of the surface with which the coating roller A of the web 1 comes into contact toward the coating roller A and the web 1 is pressurized with a line pressure less than 200 N/m by the pressurizing means B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a roll coating apparatus that performs coating (coating) on a continuously conveyed web using a coating roll, and a web manufacturing method in which a coating film is formed.

  As a coating device for forming a coating film on a continuously conveyed web, roll coating such as gravure coating method, kiss coating method, etc., using a coating roll for transferring a coating liquid to the web Devices are known and used in various fields.

A gravure coating type roll coating apparatus (hereinafter referred to as “gravure coater”) applies a coating to a web 1 that is continuously conveyed as shown in the enlarged vertical sectional schematic view of the relevant part in FIG. The coating liquid 2 is transferred from the gravure roll G, which is the coating roll A rotating in contact with the coating liquid 2 in the liquid tank H, to the web 1, and the web 1 includes an introduction side guide roll F 1, and While being guided by the lead-out side guide rail F2, it is pressed by the pressing roll E (for example, refer patent document 1).
The gravure roll G is formed with cell-shaped liquid storage recesses g, g,... Formed on the roll surface, and the coating liquid 2 is applied to the liquid storage recesses g, g,. It is filled. Then, before the coating liquid 2 is transferred to the web 1, the excess coating liquid 2 is scraped off by the doctor blade D.
Here, the coating liquid in the liquid storage recesses g, g,... Is transferred to the web 1 by the combined action of the capillary phenomenon and the pressing force, so that it is necessary to apply a relatively high pressing force by the pressing roll E. is there.

A roll coating apparatus (hereinafter referred to as “kiss coater”) such as a kiss coating method applies coating to the web 1 that is continuously conveyed, as shown in the enlarged schematic sectional view of the main part in FIG. A coating roll A that rotates in contact with the coating liquid 2 in the liquid tank H. The coating roll 3 has a smooth cylindrical surface and is coated from a coating roll 3 that does not have a liquid reservoir recess like the gravure roll G. The working fluid 2 is transferred to the web 1, and the web 1 is guided by the introduction side guide roll F <b> 1 and the outlet side guide rail F <b> 2.
Here, since there is no liquid storage recess on the roll surface of the coating roll A, when the web 1 is pressed using the pressing roller E of FIG. 6, the coating liquid 2 flows out from the width direction of the web 1. The coating film 4 cannot be formed well. Therefore, the pressure roller E as shown in FIG. 6 is not used for the kiss coater.

JP-A-5-317771

Since the gravure coater shown in FIG. 6 can apply the coating liquid 2 to the web 1 continuously conveyed using the gravure roll G, the doctor blade D, and the pressing roll E as described above. The coating film 4 having an arbitrary film thickness can be accurately formed on the web 1. Therefore, it is known that it is particularly suitable for forming a thin film and can be widely applied to high-quality products.
However, it is necessary to form the cell-shaped liquid reservoir recesses g, g,... On the surface of the gravure roll G by laser engraving, chemical etching, or machining, and to provide a doctor blade D. And since it is necessary to provide the press roll E which can provide a comparatively high pressing force, manufacturing cost increases.
In addition, the doctor blade D often has a streak defect due to foreign matter, which makes it difficult to handle and increases maintenance costs.
Furthermore, since the coating liquid 2 in the cell-shaped liquid reservoir recesses g, g,... Is transferred to the web 1, there is a disadvantage that the cell pattern remains on the coated surface of the web 1.
In addition, it is necessary to use the gravure roll G and doctor blade D, and the plate clogging of the gravure roll G and chipping of the doctor blade D may occur due to long-time operation, so it is difficult to stabilize the quality during continuous production. There is.

Further, as described above, the kiss coater shown in FIG. 7 does not include a pressing roller or a doctor blade, and does not form a liquid reservoir recess such as the gravure roll G on the roll surface of the coating roll A, so that the manufacturing cost is low. And maintenance costs can be reduced.
However, since the coating liquid 2 is attached to the coating roll 3 having no liquid reservoir recess on the surface and transferred to the web 1 as it is, the film thickness distribution in the width direction of the coating film 4 of the web 1 is uniform. In other words, since the central part is thick and the end part is thin, it cannot be applied to a product that requires high quality.

  Therefore, in view of the above-described situation, the present invention intends to solve the problem of suppressing the increase in manufacturing cost and maintenance cost, while leaving the cell pattern on the coating surface, and applying the coating liquid to the continuously conveyed web. The present invention is to provide a roll coating apparatus that can be applied as uniformly as possible and can be applied to products requiring high quality, and has high quality stability during continuous production.

  As a result of intensive studies to solve the above problems, the present inventor has completed the present invention.

That is, the gist of the present invention is as follows.
[1] Contact the coating roll that rotates in contact with the coating liquid in the coating liquid tank or the pumping roll that pumps up the coating liquid in the coating liquid tank with respect to the web that is continuously conveyed. A roll coating device for transferring the coating liquid from the rotating coating roll and forming a coating film on the web,
The coating roll has no liquid reservoir recess on the surface,
A pressing means for pressing the back surface of the web in contact with the coating roll toward the coating roll;
A roll coating apparatus, wherein the web is pressed by the pressing means at a linear pressure of less than 200 N / m.
[2] The roll coating apparatus according to [1], wherein the pressing unit is a pressing roll disposed so as to sandwich the entire web in the width direction together with the coating roll.
[3] The roll coating apparatus according to [1] or [2], further including a pressing force adjusting unit for the pressing unit.
[4] The roll coating apparatus according to [3], wherein the pressing force adjusting means is an air cylinder.
[5] A method for producing a web on which a coating film is formed, wherein the web on which the coating film is formed is continuously produced using the roll coating apparatus according to any one of [1] to [4].

According to the roll coating apparatus according to the present invention and the method for producing a web on which a coating film is formed
(1) Since no gravure roll or doctor blade is used, it is possible to suppress an increase in manufacturing cost and maintenance cost, and that no cell pattern remains on the coated surface.
(2) Since the coating film is formed while pressing the back surface of the web contacting roll with the pressing means at a linear pressure of less than 200 N / m, the coating liquid is compared with the web that is continuously conveyed. Can be applied evenly to products that require high quality,
(3) Since gravure rolls and doctor blades are not used, gravure roll clogging and chipping of doctor blades do not occur, so continuous productivity is excellent and quality stability during continuous production is high.
There are remarkable effects such as.

It is a principal part expansion longitudinal cross-sectional schematic diagram which shows the roll coating apparatus which concerns on embodiment of this invention. It is a principal part expanded partial longitudinal cross-sectional view which shows the example of a press means and its adjustment means. It is a principal part expansion longitudinal cross-sectional schematic diagram which shows the structural example provided with the backup roll. It is a principal part expansion longitudinal cross-sectional schematic diagram which shows the structural example provided with the drawing-up roll. It is a figure which shows the film thickness distribution of the web width direction of the coating film in Example 1 and Comparative Example 1. FIG. It is a principal part expansion longitudinal cross-sectional schematic diagram which shows the roll coating apparatus of the conventional gravure coating system. It is a principal part expanded vertical cross-sectional schematic which shows the roll coating apparatus of the conventional kiss coating system.

Hereinafter, the present invention will be described in detail.
The roll coating apparatus of the present invention and the method for producing a web on which a coating film is formed include an optical film, a magnetic recording tape, an adhesive tape, a photographic printing paper, an offset plate material, a battery electrode plate, a fuel cell catalyst layer, and the like. It can use suitably in each manufacture.

The web in the present invention is obtained by forming a flexible film-like substrate having a uniform thickness into a long band shape.
Examples of the substrate include paper, cloth, film, rubber, metal thin film, and thin steel plate, but are not particularly limited and can be appropriately selected depending on the application. In particular, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile-styrene copolymers, etc. Styrene polymer, polyethylene, polypropylene, polyolefin having cyclic or norbornene structure, olefin polymer such as ethylene-propylene copolymer, vinyl chloride polymer, amide polymer such as nylon (aliphatic polyamide) and aromatic polyamide, polyimide A film made of such a polymer, a film made of a blend of these various polymers, and the like can be suitably used.

The coating liquid tank in the present invention is not limited as long as it can store a required amount of the coating liquid, and an appropriate shape is selected according to required specifications and the like.
The coating liquid (coating agent) in the present invention is a resin liquid that can form a coating film by drying and curing after coating on a web. The resin material constituting the coating liquid is not particularly limited, and examples thereof include various polymers such as cycloolefin, polycarbonate, polyester, polyether ketone, polyamide, polyimide, polyamide-imide, and polyester-imide. Any one of these polymers may be used alone, or for example, a mixture of two or more kinds having different functional groups such as a mixture of polyetherketone and polyamide. Furthermore, fillers such as carbon black, metal, and ceramics may be mixed. In addition, hardening of these materials can select the hardening process according to material by drying solidification, thermosetting, ultraviolet curing, etc.

  The solvent for dissolving the resin is not particularly limited as long as it can dissolve the resin material, and can be appropriately selected according to the resin material and the base film used. Specifically, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, o-dichlorobenzene, phenols such as phenol and p-chlorophenol, methanol , Alcohols such as ethanol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, acetone, ethyl acetate, t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene Glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol, ethyl cellosolve, Use tilselsolve, 2-pyrrolidone, N-methyl-2-pyrrolidone, pyridine, triethylamine, dimethylformamide, dimethylacetamide, acetonitrile, butyronitrile, methyl isobutyl ketone, methyl ether ketone, cyclohexane, cyclopentanone, carbon disulfide, water, etc. be able to. These solvents can be used alone or in combination of two or more. Further, it may be dispersed without being dissolved.

The coating roll in the present invention is a rotating body that coats a web with a coating liquid. The roll surface does not have a liquid reservoir recess such as a gravure roll, and the roll surface is smoothly formed.
The pressing means in this invention should just press the back surface of the surface which the coating roll of a web contacts toward a coating roll, and is not limited to contact types, such as a press roll and a press plate. Alternatively, a non-contact type such as a configuration in which the pressure is applied with a gas pressure such as air or nitrogen may be used. However, in any configuration, the pressing force is set so that the linear pressure is less than 200 N / m. In order to eliminate a defect such as missing coating and to form an appropriate coating film with certainty, it is preferable to set the pressing force so that the linear pressure is 100 N / m or less.
Moreover, although the said pressing force changes with the viscosity, surface tension, etc. by the kind of coating liquid, from the viewpoint of aiming at the uniform film thickness of a coating film and improving quality, it is set as a linear pressure of 30 N / m or more. It is more preferable that the linear pressure is 40 N / m or more, and 50 N / m or more is even more preferable.

As shown in the schematic enlarged vertical sectional view of the main part of FIG. 1, the roll coating apparatus according to the embodiment of the present invention is applied to the web 1 that is continuously conveyed in the coating liquid tank H. A coating roll A that rotates in contact with the liquid 2 is formed by transferring the coating liquid 2 from the coating roll 3 that does not have a liquid reservoir recess on the surface and forming a coating film 4 on the lower surface of the web 1. is there.
The web 1 is placed closer to the coating roll 3 side than the horizontal before and after the coating roll 3 in the conveying direction of the web 1 by the introduction side guide roll F1 and the outlet side guide rail F2, that is, the coating roll 3 It is guided so that it winds up on the upstream side and slopes down on the downstream side so as to wind around the coating roll 3 side.
Moreover, the back surface (upper surface) of the surface (lower surface) with which the coating roll 3 of the web 1 contacts is pressed by the pressing roll 5 as the pressing means B at a linear pressure of less than 200 N / m.
Since the width (length) of the coating roll 3 and the pressing roll 5 is larger than the width of the web 1, the entire width direction of the web 1 is sandwiched between the coating roll 3 and the pressing roll 5.

  Here, the material constituting the pressing roll 5 may be any one of metal, resin, rubber, or the like, or may be a combination of two or more. In particular, an elastic roll having an elastic layer on the roll surface. It is preferable that There is no limitation in the kind as an elastic body which forms the said elastic layer. Examples thereof include natural rubber, styrene butadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, ethylene propylene rubber, silicon rubber, fluorine rubber and urethane rubber.

As shown in the enlarged partial longitudinal sectional view of the main part of FIG.
That is, with respect to the frame 7 that supports the rotating shaft 3A of the coating roll 3 with a bearing (not shown), the shaft support 8 that supports the rotating shaft 5A of the pressing roll 5 with a bearing (not shown) is supported so as to be slidable in the vertical direction. The shaft support 8 is driven in the vertical direction by the air cylinder 6 which is the pressing force adjusting means C.

Therefore, the pressing roll 5 is pressed against the coating roll 3 and the web 1 by its own weight including the bearing and the shaft support 8 and the thrust of the air cylinder, and the thrust of the air cylinder 6 is adjusted by adjusting the thrust. Can be adjusted.
The air cylinder 6 is a double-acting type. For example, when a thrust (F) is generated downward by the rod of the air cylinder 6, the resultant force (W + F) obtained by adding the thrust (F) to the dead weight (W) is the web 1. The force (F) obtained by subtracting the thrust (F) from the self-weight (W) acts on the web 1 by generating the thrust (F) upward by the rod of the air cylinder 6. The magnitude of the thrust (F) can be adjusted by adjusting the air pressure supplied to the air cylinder 6. Therefore, the pressing force can be adjusted by the air cylinder 6.
By configuring the pressing force adjusting means C with the air cylinder 6, the pressing force adjusting means C can be configured simply and reliably using, for example, air equipment in a factory.

The roll coating apparatus of the present invention may be provided with a backup roll 9 for preventing the pressing roll 5 from bending as shown in the main part enlarged vertical sectional schematic view of FIG.
Moreover, the roll coating apparatus of the present invention is provided with a pumping roll 10 for pumping up the coating liquid 2 in the coating liquid tank H as shown in the enlarged schematic sectional view of the main part in FIG. Also good. When the configuration including the pumping roll 10 is employed, the coating roll 3 rotates while contacting the pumping roll 10, and the coating liquid 2 is transferred from the pumping roll 10 to the coating roll 3.

<Evaluation test method>
About the following Examples and Comparative Examples, a coating film was formed on a web with a roll coating apparatus, and the formed coating film was evaluated.

(Roll coating device)
The roll coating apparatus having the configuration shown in FIGS. 1 and 2 was used, and the conveyance speed of the web 1 was set to 5 m / min.
The coating roll 3 used had a diameter of 180 mm and a width (length) of 400 mm, and the pressing roll 5 used had a diameter of 60 mm and a width (length) of 400 mm.

(web)
As the web 1, an acrylic film having a thickness of 40 μm and a width of 350 mm was used.

(Adjustment of coating solution)
Cross-linking agent (trade name: EPOCROSS WS700, manufactured by Nippon Shokubai Co., Ltd., solid content: 25%) with respect to 200 g of water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 210, solid content: 33%) 40 g was added and stirred to obtain a coating solution.

<Examples and Comparative Examples>
Example 1
1 and 2 was used, and the pressing force of the pressing roll 5 was set to a linear pressure of 100 N / m.

(Comparative Example 1)
The roll coating apparatus having the configuration shown in FIGS. 1 and 2 was used with the pressing roll 5 removed. That is, a roll coating apparatus corresponding to the kiss coater of FIG. 7 was used.

(Comparative Example 2)
1 and 2 was used, and the pressing force of the pressing roll 5 was set to a linear pressure of 200 N / m.

<Evaluation test results>
(Example 1 and Comparative Example 1)
For Example 1 (with a pressure roller, linear pressure 100 N / m) and Comparative Example 1 (without a pressure roller), after forming the coating film 4 on the web 1 with a roll coating apparatus and drying the coating film 4 The result of having measured the film thickness distribution in the position of the web 1 in the width direction is shown in FIG. The film thickness was measured by spectroscopic interference using F20 manufactured by Filmetrics Co., Ltd.
From FIG. 5, in Comparative Example 1 (without a pressure roller), the thickness distribution in the width direction of the web 1 is thick at the center and thin at the end, and the difference in thickness (maximum film thickness and minimum film thickness). It can be seen that the difference is about 66 μm.
On the other hand, in Example 1 (with a pressure roller, linear pressure of 100 N / m), the film thickness distribution in the width direction of the web 1 is relatively uniform in the width direction, and the maximum film thickness and the minimum film thickness. It can be seen that the difference is as small as about 26 μm.

(Example 1 and Comparative Example 2)
In Example 1 (with a pressure roller and a linear pressure of 100 N / m), an appropriate coating film 4 was obtained.
On the other hand, in Comparative Example 2 (with a pressure roller and a linear pressure of 200 N / m), coating omission and backside occurred, and an appropriate coating film 4 could not be obtained.

DESCRIPTION OF SYMBOLS 1 Web 2 Coating liquid 3 Coating roll 3A without the liquid storage recessed part on the surface Rotating shaft 4 Coating film 5 Press roll 5A Rotating shaft 6 Air cylinder 7 Frame 8 Shaft support body 9 Backup roll 10 Pumping roll A Coating Roll B Pressing means C Pressing force adjusting means D Doctor blade E Pressing roll F Thrust F1, F2 Guide roll G Gravure roll g Reservoir recess H Coating liquid tank W Own weight

Claims (5)

Rotates in contact with a web that is transported continuously, in contact with a coating roll that rotates in contact with the coating liquid in the coating liquid tank, or a pumping roll that pumps up the coating liquid in the coating liquid tank A roll coating apparatus for transferring the coating liquid from the coating roll to form a coating film on the web,
The coating roll has no liquid reservoir recess on the surface,
A pressing means for pressing the back surface of the web in contact with the coating roll toward the coating roll;
A roll coating apparatus, wherein the web is pressed by the pressing means at a linear pressure of less than 200 N / m.   The roll coating apparatus according to claim 1, wherein the pressing means is a pressing roll arranged so as to sandwich the entire width direction of the web together with the coating roll.   The roll coating apparatus according to claim 1, further comprising a pressing force adjusting unit for the pressing unit.   4. The roll coating apparatus according to claim 3, wherein the pressing force adjusting means is an air cylinder. The manufacturing method of the web in which the coating film was formed which manufactures continuously the web in which the coating film was formed using the roll coating apparatus of any one of Claims 1-4.

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