JPH079668A - Coating method for surface of paper and coating device - Google Patents

Abstract

PURPOSE:To perform coating on a surface of a paper material with a resin coat having a thin thickness while maintaining its moisture barrier properties and strength and sufficiently remove the resin coat with an alkaline solvent at the time of reclaiming wastepaer. CONSTITUTION:A resin layer is formed on a surface of a paper material by the processes of: forming a coat on an ultraviolet-transmissive film 7 having a smooth surface by applying a UV-curable resin coating material thereto; mounting the film thus prepared on a paper material 1 to press the coat against the surface of the paper material with pressurizing rollers 17, 18 and curing the coat by irradiating ultraviolet rays from a UV-irradiation lamp 19 through the film; and peeling the film from the paper material by a separating roller 21 to transfer the coat to the surface of the paper material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for applying a coating layer made of an ultraviolet curable resin or a resin paint to a sheet-shaped or roll-shaped long paper material, and particularly to the recycling of the paper material. Technology to facilitate.

[0002]

2. Description of the Related Art As a moisture-proof / water-proof or reinforcing process for paper materials such as high-quality paper and kraft paper, the surface of the paper material is coated with a resin film such as polyethylene. Traditional coating methods are often
Although it is carried out by an extrusion method, since a film is formed by extrusion in this extrusion method, a problem occurs in the process of recycled paper and it cannot be made a waste paper. In addition, as a recent processing technology, resin liquid coating causes impregnation of the resin liquid because the paper material is essentially porous, and the desired moisture resistance etc. is satisfied and a uniform resin film is applied to the paper surface. to form the conventional comma coater, knife coater, had to be fairly thick (about 40 g / m ² ~ about 50 g / m ² by a wet basis) coating also resin film by any technique such as Li Bath coater .

[0003]

At present, there is a great social demand for the recycling of waste paper from the viewpoint of environmental problems and the like. Here, for a resin-coated paper material, it is necessary to remove the resin film on the surface of the paper material with an alkaline solvent or the like when recycling the waste paper. However, in the related art, because the resin film is formed relatively thick on the paper surface due to the above circumstances, it is difficult to sufficiently remove the resin film, and the paper material is not actually recycled. Further, when the resin film is thinly coated by the conventional coating method, defects such as pinholes are generated and the functions such as moisture resistance cannot be exhibited.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a method and an apparatus capable of coating a relatively thin resin film on a paper surface. More specifically, the paper material surface is coated with a resin film having a thin film thickness while satisfying the required moisture resistance and strength, and the resin film can be sufficiently removed with an alkaline solvent when the used paper is recycled. The purpose is to do. The coating method of the present invention according to claim 1, which solves the above-mentioned problems, comprises a step of applying an ultraviolet-curable resin coating to an ultraviolet-transmissive film to form a coating film, and bonding the film and a paper material together. A step of pressing the coating film and the surface of the paper material together, irradiating ultraviolet rays through the film to cure the coating film, and peeling the film from the paper material by applying an external force to the paper material. And a step of transferring the coating film onto the surface of. The coating apparatus according to the present invention for solving the above-mentioned problems, is a resin coating apparatus for coating an ultraviolet-transparent film with an ultraviolet-curable resin coating material to form a coating film, and sandwiching the film and a paper material. A pair of pressure rollers for pressing the coating film onto the surface of the paper material,
And a curing device that is provided near the pressure roller and has an ultraviolet irradiation device that irradiates the coating film with ultraviolet rays through the film to cure the coating film, and peels the film from the paper material by applying an external force. And a peeling device that transfers the coating film onto the surface of the paper material, a film transport device that sequentially transports the film to a resin coating device, a curing device, and a peeling device, and a curing device and a peeling device for the paper material. And a paper material conveying device that sequentially conveys the paper material to the sheet. Further, in the coating apparatus of the present invention according to claim 3, in the coating apparatus described above, the pressure roller on the side in contact with the film is made of an ultraviolet-transparent material, and the ultraviolet irradiation device is built in the pressure roller. Then, the coating film is irradiated with ultraviolet rays through the film sandwiched between the pressure rollers. Furthermore, the coating method according to claim 4, wherein the film is coated with a resin coating material to form a coating film, the coating film is dried and semi-cured, and the film and the paper material are bonded together. And press-bonding the coating film to the surface of the paper material, curing the coating film in a state where the coating film is pressed to the paper material, and applying external force to peel the film from the paper material. And a step of transferring the coating film onto the surface of the paper material.

[0005]

In the coating method according to the first aspect of the present invention, an ultraviolet ray transmissive film is coated with an ultraviolet curable resin paint to form a coating film, and then a paper material to be coated is bonded to the film to form the coating film and the paper material. The surface of the coating film is pressure-bonded, and at the same time, ultraviolet rays are irradiated through the film to cure the coating film. This prevents the paper material from being impregnated with the resin before curing as much as possible. Then, an external force is applied to separate only the film from the paper material, and the cured coating film (resin film) is transferred to the surface of the paper material to coat the paper material. In the coating apparatus according to claim 2, the film is sequentially transported to the resin coating device, the curing device, and the peeling device by the film transporting device, and the paper material to be coated is transported to the curing device and the peeling device by the paper material transporting device. The substrates are sequentially conveyed and each step of the above coating method is carried out by a resin coating device, a curing device, and a peeling device. In the coating apparatus according to the third aspect of the present invention, the coating film is irradiated with ultraviolet rays by an ultraviolet irradiation device incorporated in the pressure roller, and the coating film is pressed onto the paper material and simultaneously cured. In the coating method according to the fourth aspect, the resin coating is applied to the film, and then the applied film is dried and semi-cured. Even if the coating film is semi-cured, the adhesive force remains. Therefore, in this semi-cured state, the film and the paper material are bonded to each other to press-bond the coating film and the surface of the paper material, and then the coating film is The coating film is cured while being pressed onto the paper material. When an external force is applied while the coating film is dry, the adhesion between the coating film and the paper material is strong, so only the film is peeled off and the coating film is transferred to the surface of the paper material.

[0006]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a diagram showing a coating apparatus according to an embodiment of the present invention. In this embodiment, the surface of the kraft paper 1 wound in a roll is coated with a film of an ultraviolet curable resin. The kraft paper 1 is held as a roll 2 in the paper material unwinding device 3, and the unwound kraft paper 1 is guided by the guide rollers 4 to wind up the paper material winding device 5
It is wound up as a roll 6. The paper material unwinding device 3, the guide roller 4, and the paper material winding device 5 constitute a paper material conveying device as a whole. During the conveyance of the kraft paper 1 by the guide roller 4, a curing device and a peeling device which will be described later. Are provided in sequence.

On the other hand, an ultraviolet-transparent long film 7 is held as a roll 8 in a film unwinding device 9, and the unwound film 7 is guided by a guide roller 10 and rolled in a film winding device 11. It is wound as 12. Film unwinding device 9 and guide roller 1
0, the film winding device 11 constitutes a film transporting device as a whole, and a resin coating device, a curing device, and a peeling device, which will be described later, are sequentially provided in the middle of transporting the film 7 by the guide roller 10.

The above-mentioned resin coating device is provided in contact with both the tank 14 for containing the solution 13 of the ultraviolet curable resin and the film 7 and the resin solution 13 and is driven to rotate corresponding to the conveying direction of the film 7. Coating roller 15 and a doctor roller 16 for removing the resin solution remaining on the coating roller 15.
It has and.

Further, the above-mentioned curing device is provided with a pressure roller 17 which is in contact with the film 7 and is rotatably driven corresponding to the transport direction of the film 7, and a pressure roller 17 which is rotatably provided. A pressure roller 18 on the receiving side for sandwiching and pinching the film 7 and the kraft paper 1 conveyed between the pressure roller 17 and the first ultraviolet irradiation lamp 19 built in the pressure roller 17, and a downstream side in the conveyance direction. The second ultraviolet irradiation lamp 20 provided near the pressure roller 17
It has and.

The above-mentioned peeling device includes a separate roller 21 for guiding the film 7 away from the kraft paper 1 and a pair of holding rollers 22 for sandwiching and guiding the kraft paper 1 against the film 7 to be peeled. , 22 and.

Here, a film made of a material having a smooth surface so that the resin does not permeate and adhere thereto, for example, an ultraviolet permeable material such as polypropylene, nylon, polyester, or the like is used. It is desirable that this film is an untreated film that has not been subjected to treatment such as corona treatment. As the ultraviolet curable resin, for example, an alkali-soluble resin such as polyvinyl alcohol or acryl / styrene is used. Considering the waste paper recycling technology that uses an alkaline solvent,
The UV-curable resin is an alkali-soluble resin, but may be a biodegradable resin paint or the like depending on the method of recycling the waste paper. The pressure roller 17 is made of, for example, a transparent glass tube, but its material is not particularly limited as long as it has strength enough to withstand pressure and necessary UV transparency.

Next, the operation of the coating apparatus having the above-mentioned structure will be described to specifically describe the coating method according to the present invention. First, the film 7 is conveyed by the film conveying device from the film unwinding device 9 to the film winding device 12 while being guided by the guide rollers 10. The coating roller 15 is driven to rotate in reverse, and the resin solution 13 in the tank 14 is attached to the outer peripheral surface of the coating roller 15 to apply the resin solution 13 to one surface of the film 7 to be conveyed. The coating amount of the coating roller 15 by the doctor roller 16 during application of the resin solution is determined, relatively thin on the film surface (about 3 g / m ² ~ about 15 g / m ² by a wet basis) and a uniform thickness of A coating film is formed.

The film 7 on which the coating film of the resin solution 13 is formed as described above is brought into contact with the pressure roller 17 on the surface on the side where the coating film is not formed, and a pair of rotating members are driven. It is wound between the pressure rollers 17 and 18.

On the other hand, the kraft paper 1 is conveyed by the guide roller 4 from the paper material unwinding device 3 to the paper material winding device 5 by the paper material conveying device. In this transport route,
The kraft paper 1 includes the film 7 and the pressure roller 17,
It is wound between 18 and is bonded to the film 7 via a coating film. Then, the ultraviolet rays from the first ultraviolet irradiation lamp 19 are applied to the coating film in a state of being pressure-bonded to the surface of the kraft paper 1 through the pressure roller 17 and the film 7, so that the resin is not sucked into the kraft paper 1. The coating film is semi-cured. In this way, film 7 and kraft paper 1
Is squeezed between the pressure rollers 17 and 18, and the coating film is pressed against the kraft paper 1 at the same time, and the coating film is cured to some extent. Therefore, even if it is porous, the kraft paper 1 is hardly impregnated with resin. In addition, there are no pinholes or the like on the coated surface.

The kraft paper 1 and the film 7 adhered by the semi-cured coating film are then conveyed from the pressure roller to the second ultraviolet irradiation lamp 20, where the ultraviolet rays from the ultraviolet irradiation lamp 20 are again emitted. The coating film is irradiated through the film 7 and the coating film is completely cured. Note that the coating film formed on the film 7 is thin, and since it is exposed to the outside air during transportation, oxygen alienation does not occur in the chemical reaction. Therefore, the curing of the coating film is completed quickly. There is no return.

When the coating film is completely cured, kraft paper 1
And the film 7 are conveyed to a peeling device, and the separate roller 21 guides the film 7 away from the kraft paper 1 and peels it off. It is clamped by the rollers 22.
As a result, the surface of the kraft paper 1 is not smooth as compared with the film 7, and since it has some permeability,
The cured coating film firmly adheres to the surface of the kraft paper 1 and remains, and only the film 7 is peeled off. Further, since the surface of the film 7 is smooth, the surface of the cured coating film thus transferred to the kraft paper 1 is in a smooth state.

The kraft paper 1 whose surface is coated with the coating film cured as described above is wound up by the winding device 5 on the roll 6, while the film 7 is taken up by the winding device 1.
It is wound into a roll 12 at 1. The cured coating film (resin film) formed by the above series of steps coats the surface of the kraft paper 1 with a relatively thin and uniform film thickness and is in a state in which the kraft paper 1 is hardly impregnated. There is.

FIG. 2 is a view showing a coating apparatus according to another embodiment of the present invention. In this embodiment, the surface of the sheet 31 is coated with a film of an ultraviolet curable resin. The same parts as those in the above embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

In this embodiment, since the sheets 31 cut into a predetermined size are to be coated, the feeding device 32 for feeding the sheets 31 one by one and the coating are used as the paper material conveying device. Sheet 31
And a stock device 33 for accommodating and accumulating in sequence. Here, the sheet 31 is not a continuous long sheet unlike the above-described embodiment, so that the feeding device 32 continuously feeds each sheet 31 between the pressure rollers 17 and 18 without a gap. It is possible to press the sheets 31 onto the coating film continuously formed on the film 7 without any gap.

Further, in this embodiment, the film 7 is of an endless type, and a film driving roller 34 is provided to drive the endless film 7 for conveyance. That is, when the roller 34 is rotationally driven by a driving unit (not shown), the endless film 7 is sequentially circulated and conveyed from the resin coating device to the curing device, the peeling device, and again to the resin coating device.

Also in this embodiment, the pressure roller 1 is applied to the coating film of the ultraviolet curable resin coating material formed on the film 7.
The sheets 31 are pasted together at 7 and 18 to form the coating film and the sheet 3
The surface of No. 1 is pressure-bonded, and at the same time, the first ultraviolet lamp 19 irradiates ultraviolet rays to semi-cure the coating film, and then the second ultraviolet irradiation lamp 20 irradiates ultraviolet rays to fully cure the coating film. After that, only the film 7 is peeled off from the sheet 31 with the separate roll 21, and the same resin film as that in the above-described embodiment can be transferred and coated on the surface of the sheet 31.

In each of the above embodiments, the resin coating device provided with the coating roller 15 is shown. However, this resin coating device only needs to be able to coat the surface of the film 7 with the ultraviolet curable resin. A method of spraying a hardened resin coating by spraying, a gravure, a flexo, a bar coater, or the like may be used.

In the above embodiment, the second ultraviolet irradiation lamp 20 for main curing the coating film is used, but the material of the ultraviolet curable resin and the first ultraviolet irradiation lamp 1 are used.
Depending on the irradiation dose of 9, the second lamp 20 may be omitted and the coating film may be fully cured only by the first lamp 19.

Further, as shown in the above embodiment, it is preferable that the ultraviolet irradiation lamp 19 is built in the pressure roller 17 so that the coating film is pressure-bonded to the paper material and cured at the same time. It is also possible to provide an ultraviolet irradiation lamp in the immediate vicinity of the downstream side of the pressure rollers 17 and 18 and to irradiate the ultraviolet rays immediately after the coating film is pressure-bonded to the paper material, even if the lamp is not incorporated.

Although all of the examples described above use the ultraviolet curable resin, it is also possible to apply a general resin liquid to the film and transfer the film in a semi-cured state. That is, the step of applying a resin coating material to the film to form a coating film, and the coating film is dried by a drying device provided between the coating roll 15 and the pressure rollers 18 and 19, so that the adhesive force of the resin liquid is increased. A step of semi-curing to the remaining state, a step of bonding the film and a paper material, and press-bonding the adhesive coating film and the surface of the paper material with pressure rollers 18, 19.
A step of curing the coating film in a state where the coating film is pressed to the paper material by a drying device provided on the downstream side of the pressure rollers 18 and 19, and applying an external force to peel the film from the paper material, The paper material may be coated with a resin by the step of transferring the coating film onto the surface of the paper material.

Even if the coating treatment is performed in this manner, the resin is not hardened to the semi-cured state at the time when the resin is pressure-bonded to the paper material. No defects such as pinholes occur. Further, since the coated resin layer is thin as in the above-mentioned embodiment, there is no problem even when recycled on waste paper.
Even if it is hardened to a semi-cured state, the coating film still retains its adhesive strength, so if it is pressed onto kraft paper with a rough surface and then dried, the surface of the paper material will have the necessary and sufficient strength. Can be coated on.

[0027]

According to the present invention, the surface of a paper material can be coated with a resin film having a small film thickness while satisfying the required moisture resistance and strength. Since the formed resin film (cured coating film) is thin and does not impregnate the paper material, it can be easily removed from the paper material with an appropriate solution at the time of recycling the waste paper. Can be played. Further, since the paper material is surface-coated with the resin film, when the paper material is processed into a bag or the like, it is possible to perform heat sealing by using the resin film as an adhesive by applying heat and pressure.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a coating apparatus according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a coating apparatus according to another embodiment of the present invention.

[Explanation of symbols]

1 Kraft paper 3 Paper material unwinding device 4 Guide roller 5
Paper material winding device 7 Film 9 Film unwinding device 10 Guide roller 11 Film winding device 13 Resin solution 14 Tank 15 Coating roller 17, 18 Pressure roller 19, 20 UV irradiation lamp 21 Separate roller 22 Holding roller 31 Sheet paper 32 paper material feeding device 33 paper material stocking device 34 drive roller

Claims (4)

[Claims] 1. A step of forming an application film by applying an ultraviolet curable resin paint to an ultraviolet permeable film, and bonding the film and a paper material to press-bond the application film and the surface of the paper material. Along with, a step of irradiating ultraviolet rays through the film to cure the coating film, and a step of peeling the film from the paper material by applying an external force, and transferring the coating film to the surface of the paper material, A method for coating a paper surface, which comprises: 2. A resin coating device that coats an ultraviolet ray transmissive film with an ultraviolet curable resin coating to form a coating film, and the film and a paper material are clamped to press the coating film onto the surface of the paper material. A pair of pressure rollers, and a curing device having a UV irradiation device which is provided in the vicinity of the pressure roller and cures the coating film by irradiating the coating film with ultraviolet rays through the film, and an external force is applied to the curing device. A peeling device for peeling the film from the paper material and transferring the coating film to the surface of the paper material, and a resin coating device for the film,
A paper surface coating device comprising: a film transport device that sequentially transports a curing device and a peeling device; and a paper material transport device that sequentially transports the paper material to a curing device and a peeling device. 3. The pressure roller on the side in contact with the film is made of an ultraviolet-transparent material, and the ultraviolet irradiation device is built in the pressure roller, and the film is sandwiched by the pressure roller. The paper surface coating apparatus according to claim 2, wherein the coating film is irradiated with ultraviolet rays. 4. A step of applying a resin coating material to a film to form a coating film, a step of drying and semi-curing the coating film, a step of laminating the film and a paper material, the coating film and the paper material. The surface of the paper material, a step of curing the coating film in a state in which the coating film is pressure-bonded to the paper material, and an external force is applied to peel the film from the paper material, and the surface of the paper material is And a step of transferring a coating film, the method for coating a paper surface.