JP2021014350A - Film correction device, digital printer, and manufacturing method of printed plastic film matter - Google Patents

Abstract

To provide a film correction device capable of suppressing sagging and curling at both sides of a film during printing, in a digital printing method for printing information, such as characters or images, on a surface of a plastic film according to an inkjet method.SOLUTION: A film correction device suppresses sagging and/or curling at both sides of a film arranging rolls for feeding the film forward while rotating and suctioning, at a lower part of the film on both sides of an ink head during digital printing for printing according to an inkjet method on a surface of a plastic film. Further, the film correction device corrects sagging in a direction that is orthogonal to a conveyance direction of a plastic film 1, and/or curling at both sides in the conveyance direction, and includes: a pair of cylindrical bodies 3a and b having suction holes 31; a rotary mechanism for rotating the pair of cylindrical bodies respectively in a direction expanding the film to its both sides; and a suction mechanism for suctioning the film through the suction holes of the cylindrical bodies.SELECTED DRAWING: Figure 1

Description

The present invention relates to a digital printing method in which a block copy does not need to be produced as in gravure printing and offset printing, and is printed by directly spraying atomized ink onto a printing medium such as a plastic film. It relates to a device capable of effectively preventing sagging and curling on both sides.

Conventionally, gravure printing has been the mainstream for printing on plastic films, specifically multilayer plastic films. On the other hand, digital printing, which enables high-definition and high-resolution printing, has been introduced into the film industry since around 2007. Unlike gravure printing, digital printing does not require the creation of block copy, so it is characterized by low manufacturing costs. In addition, since the ink that has been atomized by the inkjet method is directly sprayed for printing, vivid and beautiful printing is possible. Further, it is possible to print in a wide variety of small lots, and for example, it is possible to provide a packaging body having a different pattern depending on the season. Currently, it has been put into practical use mainly as a back print on stretched PET films, OPPs, and the like.

However, problems in such digital printing are the slack of the plastic film as the printing medium and the curl on both sides. In the conventional gravure printing, the film is pressed against the plate cylinder for printing, so that there is no problem even if the film has some slack or curl. However, in digital printing, since the film is advanced only by the guide roll, there is nothing that suppresses the slack and curl on both sides of the film, and the distance between the ink head and the film at the time of printing is currently only a few millimeters, 1-2 mm. The slack part of the film rubs against the ink head. In the case of the continuous type, which continuously discharges ink even in digital printing, the distance between the ink head and the film can be increased, so the film does not rub the ink head, but the printed characters and images are distorted. And the product cannot be shipped.

Various proposals have been made for improving the film itself as a method for suppressing sagging of the film and curling on both sides (see, for example, Patent Documents 1 and 2).

International Publication No. 2018/11039 Japanese Unexamined Patent Publication No. 2003-175543

However, it would be good if there was a device that could suppress the slack and curl on both sides of the film without improving the film itself, but a device that could suppress the slack and curl on both sides of the film was especially good. At present, no proposal has been made regarding the time of digital printing.

Therefore, an object of the present invention is a film straightening device capable of suppressing slack and curling on both sides of a film during printing in a digital printing method in which information such as characters or images is printed on the surface of a plastic film by an inkjet method. The purpose is to provide.

As a result of diligent studies to achieve the above object, the present inventors have found that by using a specific film straightening device, it is possible to suppress slack and curl on both sides of the film during printing. The present invention has been completed based on these many years of knowledge.

That is, the present invention slackens and / or installs rolls that feed the film forward while rotating and sucking at the bottom of the film on both sides of the ink head during digital printing when printing on the surface of a plastic film by an inkjet method. Provided is a film straightening device that suppresses curl on both sides.

In one embodiment of the film straightening apparatus of the present invention, a suction portion is devised so that the roll rotates in synchronization with the printing speed to feed the film forward. As a result, the rotation speed of the roll can be controlled, and the transfer speed of the film is not hindered.

Although it is the installation position of the roll, it is installed only in the lower part of the ink head, or when four ink heads are mounted such as a CMYK inkjet printing machine, not only the lower part of the ink head but also the four ink heads are combined. By installing a roll having the same length as the total length of the ink, it is possible to prevent the film from sagging and curling on both sides. The roll length may be set according to the ink head.

By rotating the roll in the outer loop direction, it is possible to suppress the slack of the film and the curl on both sides. In addition, by evacuating the inside of the roll and making suction holes in the roll, it is expected that the film can be sucked, the film is pulled to both sides, and the slack of the film and curl on both sides are suppressed. it can. In order to feed the film forward, it is preferable to make the suction holes of the roll diagonally forward.

Further, the present invention is a film straightening device for correcting slack and / or curl on both sides in the transport direction of a plastic film in a direction orthogonal to the transport direction, and comprises a pair of tubular bodies having suction holes and the above pair. Provided is a film straightening apparatus provided with a rotation mechanism for rotating a tubular body in a direction of expanding the film on both side surfaces and a suction mechanism for sucking the film from the suction holes of the tubular body.

It is preferable that each of the pair of tubular bodies has a plurality of suction holes in the direction between the reverse rotation direction of the tubular body and the film transport direction.

It is preferable that each of the pair of tubular bodies has a plurality of suction holes in the circumferential direction of the tubular body.

It is preferable that the pair of tubular bodies are provided at the lower portions of both side portions of the film.

The plastic film is preferably a multilayer film having a thickness of 30 to 100 μm.

Further, the present invention includes a guide roll on the upstream side that unwinds and conveys a roll-shaped plastic film, and a pair that rotates the unwound plastic film while sucking it from a suction hole and spreads it on both side surfaces of the film. The film straightening device provided at the lower part of both sides of the film having a tubular body located at the lower part of the ink head, and the ink head that digitally applies ink to the plastic film spread on both sides. Provided is a digital printing machine provided with a guide roll on the downstream side for transporting and winding the ink-coated plastic film in a roll shape.

Further, in the present invention, while transporting a plastic film, the film straightening device suppresses slack of the film in the direction orthogonal to the film transport direction and / or curl on both sides of the film in the transport direction, and digitally prints the film onto the film. Provided is a method for producing a plastic film printed matter, which comprises a printing step of applying an ink to form a printing layer.

As described above, the film straightening apparatus of the present invention can be preferably applied to a plastic film, and is particularly effective for printing on a multilayer plastic film having slack and curls on both sides. By preventing the film from sagging and curling on both sides and improving the flatness of the film during printing, information such as images can be brought into close contact with each other.

According to the film straightening apparatus of the present invention, it is possible to suppress slack and curl on both sides of the plastic film. Therefore, it is possible to perform digital printing with excellent aesthetics on a plastic film having slack and curls on both sides, particularly a multilayer plastic film.

It is sectional drawing which shows one Embodiment of the film straightening apparatus of this invention. It is sectional drawing which shows the mechanism which eliminates the sagging of a film by using the film straightening apparatus of this invention. It is a top view which shows one Embodiment of the arrangement of the suction hole of the tubular body used in the film straightening apparatus of this invention. It is a top view which shows the other embodiment of the tubular body used for the film straightening apparatus of this invention. It is a top view which shows the other embodiment of the tubular body used for the film straightening apparatus of this invention. It is a top view which shows the other embodiment of the tubular body used for the film straightening apparatus of this invention.

In the film straightening apparatus of the present invention, a roll for feeding the film forward while rotating and sucking is installed at the lower part of the film on both sides of the ink head during digital printing when printing on the surface of a plastic film by an inkjet method. And / or a device for suppressing curl on both sides. The film straightening device of the present invention is, for example, a film straightening device that corrects slack in a direction orthogonal to the transport direction of a plastic film and / or curls on both sides in the transport direction, and has a pair of tubular bodies having suction holes. The film is provided with at least a rotation mechanism for rotating the pair of tubular bodies in a direction of expanding the film on both side surfaces, and a suction mechanism for sucking the film through the suction holes of the tubular body.

FIG. 1 shows an embodiment of the film straightening apparatus of the present invention. FIG. 1 shows an embodiment in which the film straightening apparatus of the present invention is applied to an inkjet printing machine which is a kind of digital printing machine. 1 is a plastic film (hereinafter, may be simply referred to as "film"), 2 is an ink head, 3a and 3b are a pair of tubular bodies, 4 is a winding side film roll, 5 is a winding side film roll, and 6 And 7 are guide rolls, 8 is a winding part, 9 is a coating part, and 10 is a winding part.

In FIG. 1, the space is divided into the unwinding portion 8, the coating portion 9, and the winding portion 10 in the X-axis direction. The unwinding portion 8 is provided with an unwinding side film roll 4 and a guide roll 6 on the upstream side, which are rotationally driven by an unwinding side motor (not shown), arranged sequentially in the X-axis direction. The coating portion 9 is provided with tubular bodies 3a and 3b sequentially arranged in a direction (Y-axis direction) orthogonal to the unwinding side film roll 4 and the guide roll 6. The take-up portion 10 is provided with a guide roll 7 and a take-up side film roll 5 arranged in sequence in the X-axis direction.

In the unwinding portion 8, the film 1 to be coated with the ink in the coating portion 9 is wound around the unwinding side film roll 4 in a roll shape. Further, the film 1 is unwound from the unwinding side film roll 4, passes through the coating portion 9, and is wound around the winding side film roll 5 by the winding portion 10. In such a state, the transport direction of the film 1 is the X-axis direction, the orthogonal direction (width direction) thereof is the Y-axis direction, and the direction perpendicular to the surface is the Z-axis direction.

In the coating unit 10, while the film 1 is conveyed in the X-axis direction, the pair of tubular bodies 3a and 3b eliminates the slack and curl of the film 1, and the printing ink is ejected from the ink head 2, for example, by an inkjet method. Printing is continuously performed on the film 1 to form a printing layer. The tubular bodies 3a and 3b are connected to a rotation mechanism for rotating the film 1 in a direction of spreading toward both side surfaces and a suction mechanism for sucking the film 1 from the suction holes of the tubular body, respectively. (Not shown). The film straightening device of the present invention includes at least such a pair of tubular bodies, the rotation mechanism, and the suction mechanism.

In the embodiment shown in FIG. 1, the pair of tubular bodies (rolls) 3a and 3b are installed under the film 1 on both sides of the ink head 2 so as to feed the film forward while rotating and sucking. That is, the pair of tubular bodies 3a and 3b are provided at lower portions on both sides of the film 1 located at the lower portion of the ink head 2 of the inkjet printing machine in the transport direction at positions where the film 1 can be sucked. The tubular bodies 3a and 3b each have suction holes (through holes) on their surfaces, and the tubular bodies are installed so as to rotate in a direction in which the film 1 is spread on both side surfaces. Specifically, the tubular body 3a is installed so as to rotate in the r1 direction, and the tubular body 3b is installed so as to rotate in the r2 direction. Then, each of the pair of tubular bodies 3a and 3b rotates in a predetermined direction (r1 or r2) while sucking the back surface of the plastic film 1 from the suction holes provided on the front surface, thereby causing the film 1 to be outside in the width direction. It can be expanded to eliminate slack and / or curl on both sides of the film 1.

FIG. 2 describes a mechanism for correcting slack in a film using the film straightening device of the present invention. FIG. 2 is a schematic cross-sectional view in the film transport direction for showing a mechanism for eliminating the slack of the film by using the film straightening device of the present invention. As shown in FIG. 2A, the film 1 at the stage of being conveyed onto the pair of tubular bodies 3a and 3b has a slack S near the central portion in the width direction of the film 1. The slack S is a slack in the lower direction, but the film 1 may have a slack in the upper direction, or may have a slack in the lower direction in some parts and a slack in the upper direction in another part. is there. The tubular bodies 3a and 3b suck the back surface of the film 1 from the suction holes 31, while the tubular bodies 3a rotate in the rotation direction r1 and the tubular bodies 3b rotate in the rotation direction r2. As a result, as shown in FIG. 2B, both side portions of the film 1 sucked (adsorbed) into the suction hole 31 are pulled outward in the width direction, and the slack S is eliminated. Since the film 1 is unwound from the unwinding film roll 4 and continuously conveyed, the film 1 is continuously conveyed onto the tubular bodies 3a and 3b. Therefore, the tubular bodies 3a and 3b continuously rotate in a predetermined direction to continuously eliminate the slack and curl of the film.

In the film straightening apparatus of the present invention, the position where the pair of tubular bodies is provided is preferably the lower portions of both side portions of the film as shown in FIG. 1, but the present invention is not limited to this aspect, and both side portions of the film are provided. It may be provided on the upper part. In this case, since the pair of tubular bodies sucks both side portions of the film and rotates them so as to expand outward in the width direction, the cylinders rotate in the direction of expanding the film to both side portions as in the case of providing the lower portion of the film. The shapes are installed, but the specific rotation directions of the tubular bodies 3a and 3b are opposite to those of r1 and r2 shown in FIG.

The tubular body 3a and the tubular body 3b are provided along the X-axis direction and parallel to each other in the Y-axis direction. The tubular body 3a and the tubular body 3b have substantially the same (same or slightly longer one) length so that the introduction position of the film into the tubular body and the discharge position from the tubular body are the same. It is preferable to have.

When the film straightening device of the present invention is applied to a digital printing machine (particularly an inkjet printing machine), as shown in FIG. 1, each pair of tubular bodies is applied only to the coating portion 9, that is, the ink of the inkjet printing machine. It is preferable that the film is provided at the lower portions of both sides of the film located at the lower portion of the ink head only at the locations extending before and after the head. As a result, it is possible to prevent the film from sagging and curling on both sides only when the ink is directly sprayed. In this case, the length of the tubular body is appropriately set according to the size of the ink head. Further, when a plurality of ink heads are mounted in the film transport direction (X-axis direction), for example, in a CMYK inkjet printing machine, the distance is substantially the same not only for the lower portion of one ink head but also for the plurality of ink heads. By installing a tubular body of (same or slightly longer) length, it is possible to prevent the film from sagging and curling on both sides during ink application. The film straightening apparatus of the present invention may have a pair of tubular bodies for each ink head (for example, 4 pairs in the case of a CMYK inkjet printing machine), but the length is substantially the same as the distance over a plurality of ink heads. In this case, a pair (that is, two) of tubular bodies may be prepared, which is inexpensive. It is preferable that the distance (roll width) between the pair of tubular bodies can be adjusted according to the width of the original film.

The film straightening device of the present invention is movable so that the tubular body may be in a position where the film can be sucked or contacted in order to suck the film during operation, and the film is not sucked when not in operation. There may be. As described above, the film straightening device of the present invention may have a mechanism for moving the tubular body to a position where the film is sucked and a position where the film is not sucked.

For example, when the coating target area of the film 1 reaches the coating portion 9, the suction holes of the tubular bodies 3a and 3b are set in a state where vacuum suction is possible, and the film 1 is used for coating the coating target area with ink. The operation is started, and the tubular bodies 3a and 3b are operated while the film 1 is under tension in the X-axis direction, and the film 1 is vacuum-sucked to correct curl and slack on the side surface. The operation of the tubular bodies 3a and 3b may be stopped before the coating target region of the film 1 reaches the coating portion 9 and after passing through the coating portion 9, and / or the tubular bodies 3a and 3b may be referred to, for example. It may be lowered to the retracted position.

The tubular bodies 3a and 3b are preferably cylindrical bodies, but may be polygonal tubular bodies as long as the effects of the present invention are not impaired.

FIG. 3 shows a schematic top view of the tubular body 3a (FIG. 3 (a)) and the tubular body 3b (FIG. 3 (b)), respectively. The tubular body 3a is provided with a plurality of suction holes 31 on the surface thereof. The plurality of suction holes 31 are arranged at equal intervals in the direction L1 between the reverse rotation direction Rr1 (direction opposite to the rotation direction r1, Y-axis direction) of the tubular body 3a and the film transport direction (X-axis direction). It is equipped. The plurality of suction holes 31 having the direction L1 may be provided on a straight line, or may be provided so as to be curved toward the film transport direction side or the reverse rotation direction Rr1 side. The angle θ1 formed in the reverse rotation direction Rr1 and the direction L1 may be more than 0 ° and less than 90 °, preferably 10 to 80 °. Since the plurality of suction holes 31 are provided in the direction L1 in this way, the tubular body 3a rotates in the rotation direction r1 to suck the film side side portion and expand it outward in the width direction to eliminate slack and curl. At the same time, the film can be smoothly conveyed in the conveying direction.

Further, it is preferable that the plurality of suction holes 31 are continuously provided along the circumferential direction (Y-axis direction), particularly at equal intervals. As a result, the slack and curl of the film can be continuously eliminated at a gentle rotation speed. In particular, as shown in FIG. 3A, the plurality of suction holes 31 are preferably provided in the direction L1 and parallel to the circumferential direction.

The tubular body 3b is provided with a plurality of suction holes 31 on the surface thereof. The plurality of suction holes 31 are provided in the direction L2 between the reverse rotation direction Rr2 (direction opposite to the rotation direction r2) and the film transport direction (X-axis direction) of the tubular body 3b, particularly at equal intervals. .. The plurality of suction holes 31 provided in the direction L2 may be provided on a straight line, or may be provided so as to be curved toward the film transport direction side or the reverse rotation direction Rr2 side. The angle θ2 formed in the reverse rotation direction Rr2 and the direction L2 may be more than 0 ° and less than 90 °, preferably 10 to 80 °. Since the plurality of suction holes 31 are provided in the direction L2 in this way, the tubular body 3b rotates in the rotation direction r2 to suck the film side side portion and expand it outward in the width direction to eliminate slack and curl. At the same time, the film can be smoothly conveyed in the conveying direction.

Further, it is preferable that the plurality of suction holes 31 are provided at equal intervals along the circumferential direction (Y-axis direction). As a result, the slack and curl of the film can be continuously eliminated at a gentle rotation speed. In particular, as shown in FIG. 3B, the plurality of suction holes 31 are preferably provided in the direction L2 and parallel to the circumferential direction.

It is preferable that the arrangement of the plurality of suction holes 31 in the tubular body 3a and the arrangement of the plurality of suction holes 31 in the tubular body 3b are symmetrical.

The hole diameter (diameter) of the suction hole 31 may be such that the film can be sufficiently sucked and can be sucked in the transport direction (X-axis direction), for example, 2 to 10 mm, preferably 3 to 3. It is about 5 mm. When the hole diameter is 2 mm or more (particularly 3 mm or more), the suction force becomes sufficient, and slack and curl can be suppressed more effectively. When the pore diameter is 10 mm or less (particularly 5 mm or less), the suction force does not become too high, and the film can be conveyed more appropriately in the conveying direction.

The shape of the suction hole 31 is preferably circular, but it may be polygonal as long as the effect of the present invention is not impaired.

When it is desired to change the suction strength, it is preferable to increase the number of suction holes rather than increasing the size of the suction holes. For example, when the diameter of the tubular body is 30 mm, it is preferable to prepare suction holes at intervals of 5 to 50 mm. However, since the degree of suction changes depending on the diameter of the tubular body, it is necessary to select it appropriately. The [distance between suction ports (distance between centers of adjacent suction ports) / outer diameter of the tubular body] is, for example, 0.1 to 0.8, preferably 0.15 to 0.6.

When it is difficult to increase the number of suction holes, a part of the tubular body may be made into a mesh plate 32, for example, as in the tubular body 4a shown in FIGS. 4 to 6. The net plate 32 also corresponds to the suction hole. As a result, it is possible to increase the suction force without changing the degree of vacuum. In the tubular body 4a shown in FIGS. 4 to 6, the arrangement of the net slab 32 is not particularly limited and can be changed as appropriate. For example, the net plates 32 shown in FIGS. 4 to 6 may be arranged symmetrically or vertically symmetrically. Further, it is preferable that the arrangement of the net slab in the tubular body (not shown) paired with the tubular body 4a is symmetrical with the arrangement in the tubular body 4a.

The material of the tubular body is not particularly limited, but stainless steel and plastic are preferable. Further, it is more preferable to have antistatic performance. The diameter (diameter) of the tubular body can be appropriately selected according to the size of the digital printing machine, but is preferably 25 to 100 mm, more preferably 50 to 70 mm.

The film straightening apparatus of the present invention satisfactorily causes slack and side curls of a film at the lower part of the film, for example, the lower part of the central portion in the width direction where slack is likely to occur, without providing a film support between the pair of tubular bodies. It can be resolved.

The plastic film used in the film straightening apparatus of the present invention is not particularly limited, but is preferably a multilayer film (particularly, a multilayer coextruded film). This is because the multilayer film (particularly, the multilayer coextruded film) often has an asymmetrical structure in the thickness direction due to differences in the resin component and the thickness ratio of each layer, and slack and curl are likely to occur. The plastic film may be a sheet-shaped film (flat film) or a film in which a tubular film is flattened.

The thickness of the plastic film is not particularly limited, but is preferably 30 to 100 μm. The film straightening apparatus of the present invention is particularly suitable for eliminating slack and curl of a plastic film having such a thickness.

The film straightening device of the present invention can temporarily eliminate the slack and curl even if the film has slack and curl, regardless of the improvement of the film. Therefore, for example, as shown in FIG. 1, it is particularly preferable to use it in combination with a digital printing machine such as an inkjet printing machine. The usage mode of the film straightening device of the present invention is not limited to this, and can be applied to any device for eliminating slack and side curl of the film. For example, it can be preferably used for the purpose of temporarily eliminating slack and curl of a film when laminating with another film.

A plastic film printed matter can be produced by using the film straightening device and the digital printing machine of the present invention. Specifically, while transporting a plastic film, ink is applied onto the film by digital printing (for example, an inkjet method) while suppressing slack and / or curling on both sides of the transport direction in the direction orthogonal to the film transport direction. A plastic film printed matter can be produced by a method having a printing step of forming a printing layer.

The transport speed of the plastic film is not particularly limited, but is preferably 150 m / min or less from the viewpoint of eliminating slack and curling and printing at the same time.

The degree of vacuum when the film is sucked from the suction holes by the pair of tubular bodies is appropriately set according to the number of suction holes and the hole diameter, but is preferably 12 to 40 kPa. However, since the degree of suction differs depending on the width and thickness of the film, it is preferable to be able to adjust it according to the situation.

The rotation speed of the tubular body is preferably a drive structure that can be synchronized with the printing speed, but is preferably 20 to 80 rpm. However, it should be selected appropriately according to the diameter of the tubular body.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples. A plastic film was prepared as a printing medium. The details of the film are as follows.
-Multilayer coextruded flat film A (composition: nylon / adhesive layer / polyethylene, thickness: 50 μm)
-Multilayer coextruded tube film B (composition: nylon / adhesive layer / polyethylene, thickness: 50 μm)
-Multilayer coextruded tube film C (with side seal, composition: nylon / adhesive layer / polyethylene, thickness: 50 μm)

Examples 1-3
The films A to C were digitally printed by an inkjet method using the film straightening apparatus shown in FIG. 1 while eliminating the slack and curl of the film to prepare a plastic film printed matter. The film transport speed is 50 mm / min according to the printing speed, the rotation speed of the pair of tubular bodies is 40 rpm, and the degree of vacuum inside the tubular bodies is 36 kPa. As the tubular body, as shown in FIG. 3, a pair of tubular bodies provided with a plurality of suction holes along the direction L1 or the direction L2 and in the circumferential direction were used. The diameter of the tubular body is 30 mm.

Comparative Examples 1-3
The films A to C were digitally printed by an inkjet method in the same manner as in Examples 1 to 3 except that the film straightening device was not used, to produce a plastic film printed matter.

(Evaluation)
The slack, curl, and rubbing against the ink head of the film were evaluated during digital printing performed in Examples and Comparative Examples. The criteria for each evaluation are as follows. The results are shown in Table 1.

(1) Slack and curl The case where the slack or curl was eliminated at the time of printing was evaluated as ◯, the case where the slack or curl was relatively small was evaluated as Δ, and the case where the slack or curl was relatively large was evaluated as ×.

(2) Rubbing with the ink head The case where the rubbing between the ink head and the film did not occur during printing was evaluated as ◯, and the case where the rubbing occurred was evaluated as x.

As can be seen from Table 1, by using the film straightening apparatus of the present invention, both the flat film and the tube film were prevented from sagging and curling on both sides, and no rubbing with the ink head was confirmed. Further, when the same film was used and the film straightening device of the present invention was not used, the curl on both sides of the tube film was not confirmed to be the same as that of the flat film, but the upper part (ink head side) like the flat film. Since slack was confirmed, rubbing against the ink head was also confirmed.

As a summary of the above, the configuration of the present invention and its variations thereof will be added below.
[1] A film straightening device that suppresses slack and / or curl on both sides of a film during digital printing by printing on the surface of a plastic film by an inkjet method.
[2] The film straightening apparatus according to [1], wherein rolls for feeding the film forward while rotating and sucking are installed under the film on both sides of the ink head.
[3] A film straightening device for correcting slack and / or curl on both sides in the transport direction of a plastic film, which is a pair of tubular bodies having suction holes and the pair of tubular bodies. A film straightening device provided with a rotation mechanism for rotating each of the films in a direction of spreading toward both sides of the film and a suction mechanism for sucking the film from the suction holes of the tubular body.
[4] The film straightening apparatus according to [3], wherein each of the pair of tubular bodies has a plurality of suction holes in a direction between the reverse rotation direction of the tubular bodies and the film transport direction.
[5] The film straightening apparatus according to [3] or [4], wherein each of the pair of tubular bodies has a plurality of suction holes in the circumferential direction of the tubular body.
[6] The film straightening device according to [4] or [5], wherein each of the pair of tubular bodies is provided with the plurality of suction holes so as to be arranged symmetrically.
[7] The film straightening apparatus according to any one of [3] to [6], wherein the pair of tubular bodies are provided at lower portions on both sides of the film.
[8] The film straightening apparatus according to any one of [3] to [7], wherein the pair of tubular bodies are provided parallel to each other in a direction orthogonal to the film transport direction along the film transport direction. ..
[9] The film straightening apparatus according to any one of [3] to [8], wherein the pair of tubular bodies have substantially the same length.
[10] The film straightening apparatus according to any one of [3] to [9], which does not have a film support between the pair of tubular bodies.

[11] The film straightening apparatus according to any one of [1] to [10], wherein the plastic film is a multilayer film having a thickness of 30 to 100 μm.
[12] A guide roll on the upstream side that unwinds and conveys a roll-shaped plastic film, and a pair of tubular bodies that rotate while sucking the unwound plastic film from a suction hole and spread it on both side surfaces of the film. The film straightening device according to any one of [1] to [11] provided at the lower part of both side portions of the film located at the lower part of the ink head, and digitally on the plastic film spread on both side sides. A digital printing machine provided with the ink head for applying ink by a method and a guide roll on the downstream side for transporting the plastic film coated with ink and winding it into a roll.
[13] While transporting the plastic film, the film straightening device is used to slacken the film in the direction orthogonal to the film transport direction and / or curl both sides of the film in the transport direction to any one of [1] to [12]. A method for producing a plastic film printed matter, which comprises a printing process of applying ink on a film by digital printing to form a printing layer while suppressing the printing.

The film straightening apparatus of the present invention can perform digital printing for printing information such as characters or images having excellent aesthetics by an inkjet method even on a plastic film having slack or side curl.

1 Plastic film 2 Ink head 3a, 3b, 4a Cylindrical body 31 Suction hole 32 Net plate

Claims (8)

Print on the surface of a plastic film by an inkjet method Install a roll that feeds the film forward while rotating and sucking at the bottom of the film on both sides of the ink head during digital printing. Suppresses slack and / or curl on both sides of the film. Film straightening device. A film straightening device that corrects slack and / or curl on both sides of the transport direction of a plastic film in a direction orthogonal to the transport direction, and forms a pair of tubular bodies having suction holes and the pair of tubular bodies, respectively. A film straightening device provided with a rotation mechanism for rotating the film in a direction of spreading to both side surfaces and a suction mechanism for sucking the film from the suction holes of the tubular body. The film straightening apparatus according to claim 2, wherein each of the pair of tubular bodies has a plurality of suction holes in a direction between the reverse rotation direction of the tubular bodies and the film transport direction. The film straightening apparatus according to claim 2 or 3, wherein each of the pair of tubular bodies has a plurality of suction holes in the circumferential direction of the tubular body. The film straightening apparatus according to any one of claims 2 to 4, wherein the pair of tubular bodies are provided on lower sides of both sides of the film, respectively. The film straightening apparatus according to any one of claims 1 to 5, wherein the plastic film is a multilayer plastic film having a thickness of 30 to 100 μm. An ink head consists of a guide roll on the upstream side that unwinds and conveys a roll-shaped plastic film, and a pair of tubular bodies that rotate while sucking the unwound plastic film from a suction hole and expand it to both sides of the film. The film straightening apparatus according to any one of claims 1 to 6 provided at the lower part of both side portions of the film located at the lower part, and the plastic film spread on both side sides are digitally coated with ink. A digital printing machine comprising the ink head to be used and a guide roll on the downstream side for transporting the plastic film coated with the ink and winding it into a roll. Digital printing while transporting the plastic film, while suppressing the slack of the film in the direction orthogonal to the film transport direction and / or the curl on both sides of the film in the transport direction by the film straightening device according to any one of claims 1 to 6. A method for producing a plastic film printed matter, which comprises a printing step of applying ink onto a film to form a printing layer.

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