WO2014083722A1

WO2014083722A1 - Printing method using offset printer

Info

Publication number: WO2014083722A1
Application number: PCT/JP2013/004440
Authority: WO
Inventors: 真吾河合
Original assignee: 大和グランド株式会社
Priority date: 2012-11-28
Filing date: 2013-07-22
Publication date: 2014-06-05
Also published as: EP2927010B1; JPWO2014083722A1; EP2927010A4; JP5824073B2; EP2927010A1

Abstract

[Problem] To provide a printing method using an offset printer with which image formability is excellent. [Solution] The present invention is a printing method using an offset printer (10) having: multiple conveyor rolls (6) for conveying a printing object (8); blankets (3) adjacent to the conveyor rolls (6); waterless plates (2) adjacent to the blankets (3); ink conveyor roll groups (1) adjacent to the waterless plates (2); and a UV irradiator (5) for irradiating UV on the printed printing object (8). The printing method: comprises an offset printing process (S1) for printing a UV-curable ink applied on a waterless plate (2), after transfer to a blanket (3), on the printing object (8), and a UV irradiation process (S2) for irradiating UV on the printed printing object (8) to cure the UV-curable ink; and uses an offset printer (10) in which the running speed of the printing object (8) is 1700 m/hour or less and the film thickness of the applied UV-curable ink is 3-7 µm.

Description

Printing method using offset printing press

The present invention relates to a printing method using an offset printing press, and more particularly, to a printing method using an offset printing press that is excellent in image formability.

Offset printing is known as one of printing techniques.
Such offset printing employs a method in which ink attached to a plate is transferred to an intermediate transfer member such as a blanket and then printed on a substrate such as paper.

Heretofore, in the field of offset printing, a method of operating an offset printing press at high speed has been studied from the viewpoint of shortening delivery time and cost.
For example, offset printing using a quick-drying ink that is cured by irradiating the printing surface of a running printing substrate with ultraviolet light through a printing plate mounted on the periphery of a printing cylinder and a blanket mounted on the outer periphery of a blanket cylinder A printing press is known (see, for example, Patent Document 1).
In the offset printing press, high-speed operation is possible by using fast-drying ink.

On the other hand, there is disclosed a reverse printed material in which a printing layer by offset printing is provided on a substrate having transparency, and a white ink is applied on the printing layer using a coater (for example, Patent Document) 2).
Such printed matter is offset printed on a corona discharge treated polypropylene sheet using an ultraviolet curable ink, and UV cured at a printing speed of 6500 sheets / hour (about 30 m / minute).

By the way, in offset printing, printing is generally performed with a water plate using water.
In the printing with a water plate, it is possible to manage not only the supply of the ink but also the amount of water applied to the plate, such as the amount of ink buildup and the edge of the pattern.

However, since the amount of watering depends on the humidity, temperature, etc. in the air, there is a disadvantage that the image quality is not stable.
Further, since emulsification proceeds with each other at the boundary between water and ink, there is a disadvantage that the quality is deteriorated if the emulsified portion remains. In this case, it is also difficult to post-process the film or plate separately after offset printing, or to insert a resin after post-processing.

On the other hand, in recent years, in offset printing, a waterless plate having a structure in which a handle is oleophilic and a non-image portion (a portion not to be printed) is formed with a silicon layer has been developed.
In printing without a water plate, since water is not used, the problems of image quality variation due to the amount of water applied and the problem of emulsification with water and ink are solved.

JP, 2009-274432, A JP 2007-296830 A

However, in waterless printing, the formability of the image is not sufficient. That is, the transferability of the ink from the waterless plate to the blanket and the transferability of the ink from the blanket to the printing medium are not necessarily sufficient.
In addition, the ink suitable for offset printing with a waterless plate which solves such a problem, and a to-be-printed body have not been developed yet.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a printing method using an offset printing press which is excellent in image formability.

The inventor of the present invention has made earnest studies to solve the above problems, and by making the printing speed of offset printing actively lower than a general speed and making the film thickness of the UV curable ink a constant film thickness. Surprisingly, it has been found that the above problems can be solved, and the present invention has been completed.

According to the present invention, there are provided (1) a plurality of transport rolls for transporting a printing material, a blanket adjacent to the transport rolls, a waterless plate adjacent to the blanket, and a group of ink transport rolls adjacent to the waterless plate. A printing method using an offset printing press having a UV irradiator for irradiating the printed substrate with UV, after transferring the UV curable ink applied to the waterless plate to a blanket, The printing method has an offset printing step of printing on a substrate and a UV irradiation step of irradiating the printed substrate with UV to cure the UV curable ink, and the traveling speed of the substrate is 1700 m. The printing method using an offset printing press which has a film thickness of 3 to 7 .mu.m or less, which is not more than 1 hour, is applied.

The present invention resides in (2) a printing method using the offset printing press as described in (1) 1 above, wherein the traveling speed of the printing medium is from 250 m / hour to 1700 m / hour.

The present invention resides in (3) the printing method using the offset printing press described in the above (1) or (2), wherein the substrate is a non-water absorbing synthetic paper, a plastic film or a paper board.

In the present invention, (4) the ink conveyance roll group includes a temperature adjustment ink conveyance roll for adjusting the temperature of the UV curable ink, and the hot water is circulated in the core portion of the temperature adjustment ink conveyance roll. The printing method using the offset printing press according to any one of the above (1) to (3).

In the present invention, (5) the temperature of the UV curable ink is adjusted to 20 ° C. to 50 ° C. by the temperature adjustment ink transport roll, and the viscosity of the UV curable ink is 5 Pa · s to 1500 Pa. The printing method using the offset printing press according to (4) above, wherein s is used.

According to the present invention, (6) a U-shaped guide is provided below the transport roll so as to conform to the shape of the transport roll, according to any one of the above (1) to (5) It belongs to a printing method using an offset printing press.

The present invention resides in (7) the printing method using the offset printing press according to the above (6), wherein the air is blown between the transport roll and the guide so that the printing material does not drip downward. .

The present invention resides in (8) a printing method using the offset printing press according to any one of the above (1) to (7), which is subjected to post-processing after offset printing and UV irradiation. .

The present invention resides in (9) a printing method using the offset printing press according to the above (8), wherein the post-processing is silk screen printing.

In the printing method using the offset printing press of the present invention, the transfer speed of the UV curable ink from the waterless plate to the blanket can be reduced by setting the printing speed of the offset printing to a predetermined range. Transferability of the UV curable ink to the print can be improved.
For example, since the printing speed is slow, the density of the UV curable ink can be increased, and the transfer amount can also be increased. Thereby, the film thickness of the UV curable ink can also be 3 to 7 μm.
In addition, since the film thickness can be 3 to 7 μm, not only the decorative property can be improved, but various functional inks can be used to sufficiently exhibit the function.
Furthermore, since the printing speed is slow, UV irradiation can be performed sufficiently, and the curing strength of the UV curable ink can be raised to a level that can sufficiently withstand post-processing.

In the printing method using the offset printing press of the present invention, since the waterless plate is used, it is possible to prevent the dispersion of the image quality due to the watering amount and the emulsification of the water and the UV curable ink.
In addition, since the waterless plate is used, the influence of static electricity in the image area (portion to be printed) can be minimized. As a result, automatic feeding and conveyance can be performed without problems even for materials such as molding materials that are not subjected to static electricity prevention.

In the printing method using the offset printing press of the present invention, since UV curable ink is used, it is possible to immediately start post-processing by irradiating UV, which leads to shortening of delivery time.
From these facts, according to the printing method using the offset printing press of the present invention, a printed body having excellent image formability can be obtained.

In the printing method using the offset printing press of the present invention, when the printing material is a non-water absorbent synthetic paper, a plastic film or a paper board, the image forming property is improved by setting the printing speed within the above range. It is possible to improve, and by using the UV curable ink, it is possible to perform offset printing at a speed that does not burden the post-processing speed.

In the printing method using the offset printing press of the present invention, the ink transport roll group is provided with a temperature control ink transport roll for controlling the temperature of the UV curable ink, and the core portion of the temperature control ink transport roll is warm water Because it is in circulation, the applied UV curable ink can be heated or cooled to adjust its temperature. In addition, when the printing speed of offset printing is fast, the UV curing ink is heated and easily transferred by heat due to friction, but when the printing speed of offset printing is slow as in the present invention, the UV curing ink Is difficult to transfer because it is not heated. Therefore, it is necessary to heat it.
At this time, it is preferable to adjust the temperature at the time of use of the UV curable ink to 20 ° C. to 50 ° C., and to set the viscosity at the time of use of the UV curable ink to 5 Pa · s to 1500 Pa · s.

In the printing method using the offset printing press of the present invention, a U-shaped guide is provided below the transport roll so as to conform to the shape of the transport roll, so a part of the printing medium is below It is possible to prevent such a situation that the printed matter is wrinkled or the like between the transport rolls. In addition, when the printing speed of offset printing is high, since a to-be-printed body winds around a conveyance roll by the momentum of rotation of a conveyance roll, such a situation does not occur.
At this time, when air is blown between the transport roll and the guide, the printed material can be further prevented from dropping downward.

In the printing method using the offset printing press of the present invention, when post-processing is performed after offset printing and UV irradiation, a print having excellent decorativeness can be obtained. At this time, when the post-processing is silk screen printing, the printing speeds of offset printing and silk screen printing can be made to coincide with each other, so that offset printing and silk screen printing can be applied continuously.

FIG. 1 is a schematic view showing an offset printing press used in a printing method according to the present embodiment. FIG. 2 is a flowchart showing a printing method using the offset printing press according to the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as needed. In the drawings, the same elements will be denoted by the same reference signs and redundant description will be omitted. Further, the positional relationship such as upper, lower, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratio in the drawings is not limited to the illustrated ratio.

FIG. 1 is a schematic view showing an offset printing press used in a printing method according to the present embodiment.
As shown in FIG. 1, the offset printing press 10 includes a plurality of transport rolls 6 for transporting the printing medium 8, a blanket 3 adjacent to the transport rolls 6, a waterless plate 2 adjacent to the blanket 3, and no water. An ink transport roll group 1 adjacent to the printing plate 2 and a UV irradiator 5 for irradiating the printed substrate 8 with UV are included.
Here, the ink transport roll group 1 is an assembly of inking rolls or anilox rolls. In addition, only an inking roll may be collected, only an anilox roll may be collected, or both may be mixed and collected.

In the offset printing press 10, the printing medium 8 is conveyed by rotating the conveying rolls 6 adjacent to each other in the direction indicated by the arrow while holding the printing medium 8 therebetween. There is.
The blanket 3, the waterless plate 2 and the ink transport roll constituting the ink transport roll group 1 and the temperature control ink transport roll described later are all cylindrical and correspond to the rotational direction of the transport roll 6. Each is rotated in a different direction or in the same direction.
At the time of rotation, transfer of the UV curable ink is performed.

In the offset printing press 10, as described above, the ink transport roll group 1 includes the plurality of ink transport rolls and the temperature control ink transport roll 1a disposed between the ink transport rolls.
The temperature control ink transport roll 1a has a core-sheath structure in which the core portion is hollow, and hot water flows through the core portion. Thereby, the temperature of the UV curable ink is adjusted. When it is not necessary to heat the UV curable ink with warm water, it is not necessary to pass warm water, and conversely, when cooling is required, it is possible to circulate cold water.
As described above, the ink transport roll is an inking roll or an anilox roll, and the temperature control ink transport roll is an inking roll or an anilox roll having a core-sheath structure.

In the offset printing press 10, a U-shaped guide 4 is provided below the transport roll 6 so as to follow the shape of the transport roll 6. For this reason, it is possible to prevent a situation in which a part of the printing medium 8 hangs downward, and the printing medium 8 is folded between the transport rolls 6 and rolled up, and the printing medium 8 is wrinkled.
Further, air is blown between the transport roll 6 and the guide 4 by an air blower or the like (not shown) so that the printing medium 8 does not hang downward. For this reason, it is possible to further prevent the printing medium from hanging down.

Here, it is preferable that the to-be-printed body 8 is a non-water absorbing synthetic paper, a plastic film, or a paper board.
By using these printing materials 8, the product (printed material) can be reduced in weight and durability can be imparted.

The plastic film is not particularly limited. For example, polyester film, polyethylene film, polyethylene naphthalate film, polypropylene film, polyamide film, polyamide film, polyimide film, polyvinyl alcohol film, polyvinyl chloride film, polyvinylidene chloride film, polycarbonate film Polystyrene film, polyacrylonitrile film, ethylene vinyl acetate copolymer film, ethylene-vinyl alcohol copolymer film, ethylene-methacrylic acid copolymer film, cellulose triacetate film, ionomer film, cellophane etc. are used.

In the offset printing press 10, the UV curable ink is applied from the ink transport roll group 1 to the waterless plate 2 and is printed on the printing material 8 through the waterless plate 2 and the blanket 3. . The details of these will be described later.

Here, in the offset printing press 10, a UV curable ink is used.
Since a UV curable ink is used, it is possible to immediately start post-processing by irradiating UV, and lead to shortening of delivery time.
At this time, as described above, since the waterless plate 2 is used as the plate, it is preferable that the UV curable ink be lipophilic.
By making it lipophilic, there is an advantage that the lipophilic portion to be a handle of the waterless version 2 is well blended.

The UV curable ink contains a UV curable resin, a polymerization initiator, and a pigment. In addition, additives such as a solvent, a sensitizer, a polymerization inhibitor, an antifoaming agent, and a surfactant may be further included.
Examples of the UV curable resin include acrylate-based, methacrylate-based and unsaturated polyester-based resins having a polymerizable ethylenic double bond. More specifically, polyester acrylate, epoxy acrylate, urethane acrylate and the like can be mentioned.
Examples of the polymerization initiator include benzophenones, benzoins, acetophenones, and thioxanthones.

Further, as described later, since the film thickness can be made sufficiently thick, the UV curable ink can also contain a functional ink.
Here, as the functional ink, a conductive ink, an insulating ink, a temperature-sensitive ink, a hydrophilic water coloring ink, a perfume ink, an ultraviolet coloring ink, a fluorescent ink, a luminous ink, etc. may be mentioned. All of these functions are exhibited by leveling with a thick film. By the way, if you do not get a certain amount of dryness, that function will not be exhibited.
Therefore, when functional ink is used, not only the decorativeness can be improved, but also its function can be fully exhibited.

The temperature at which the UV curable ink is used is preferably 20 ° C. to 50 ° C. In addition, this temperature is adjusted by the temperature control ink conveyance roll 1a mentioned above.
In addition to the temperature at the time of use of the UV curable ink being in the above range, the viscosity at the time of use of the UV curable ink is preferably 5 Pa · s to 1500 Pa · s.
At the time of use, the physical properties of the UV curable ink are within the above range, transfer of the UV curable ink to the waterless plate 2, transfer of the UV curable ink to the blanket 3, and UV to the printing material 8 Transfer of the curable ink can be performed reliably and stably.

The UV irradiator 5 is a device for irradiating the printed substrate 8 with UV.
The UV irradiator 5 is not particularly limited, and a commercially available one can be used as appropriate.
The UV irradiator 5 may be installed inside the offset printing press 10, for example, between cylinders, or may be installed outside.

FIG. 2 is a flowchart showing a printing method using the offset printing press according to the present embodiment.
As shown in FIG. 2, in the printing method using the offset printing press 10, the UV curable ink applied to the waterless plate 2 is transferred to the blanket 3 by the ink transport roll group 1, and then the printing material 8 is printed. And an UV irradiation step S2 in which the printed substrate 8 is irradiated with UV to cure the UV curable ink.
In the printing method using the offset printing press 10, the offset printing step S1 and the UV irradiation step S2 are continuously performed.

In the offset printing step S 1, the UV curable ink is applied to the waterless plate 2 by the ink transport roll group 1.
Here, in the printing method using the offset printing press 10, since the ink transport roll group 1 is used, when applying the UV curable ink to the waterless plate 2, even if the printing speed is low, a constant amount The ink can be supplied stably.
In addition to this, when an inking roll is used, mist is generated, but generation of mist can be prevented by using the ink transport roll group.

Further, in the printing method using the offset printing press 10, since the waterless plate is used, it is possible to prevent the dispersion of the image quality due to the amount of watering and the emulsification of the water and the UV curable ink.
In addition to this, the influence of static electricity in the image area (the part to be printed) can be reduced.

Then, the UV curable ink applied to the waterless plate 2 is transferred to the rubber blanket 3 and then printed on the recording material 8.
At this time, the traveling speed of the printing medium 8 is low. The traveling speed of the printing medium 8 and the printing speed of the printing medium 8 are the same so as to correspond to each other. Therefore, by setting the traveling speed of the printing medium 8 low, the printing speed on the printing medium 8 becomes slow.
Specifically, the traveling speed of the printing medium 8 is 1700 m / hour or less, preferably 250 m / hour to 1700 m / hour, and more preferably 250 m / hour to 1500 m / hour.
Transferability of the UV curable ink from the waterless plate 2 to the blanket 3 and transfer of the UV curable ink from the blanket 3 to the substrate 8 by setting the traveling speed of the substrate 8 to 1700 m / hour or less Can be improved. In addition, the printing speed in the common offset printing machine marketed is 3000 m / hour at the minimum.

Also, the concentration of the UV curable ink can be increased, and the transfer amount can also be increased. Thereby, the film thickness can be increased.
Specifically, in the printing method using the offset printing press 10, the film thickness of the UV curable ink applied is 3 to 7 μm. The film thickness of the UV curable ink in a general offset printing press is 1 to 2 μm.
As described above, since the film thickness can be 3 to 7 μm, it is possible not only to improve the decorativeness but also to fully exhibit the function using various functional inks.
Furthermore, UV irradiation can be performed sufficiently, and the curing strength of the UV curable ink can be raised to a level that can sufficiently withstand post-processing.

In the offset printing press 10 according to the present embodiment, as described above, the printed material 8 is made of non-water absorbent synthetic paper, plastic film or plastic plate, and the printing speed is in the above range to form an image. It is possible to improve the properties, and as described above, by using the UV curable ink, it is possible to perform offset printing at a speed at which the post-processing speed is not a burden.
In the case of a water-absorbent printed material, when the printing speed is slow, the water-absorbent synthetic paper absorbs the moisture in the air, and when the UV-curable ink is applied, the UV-curable ink bleeds. There is.

In the UV irradiation step S2, the printed substrate 8 is irradiated with UV to cure the UV curable ink.
The UV irradiation method is not particularly limited, and may be performed by a conventionally known method.

Through the above steps, according to the printing method using the offset printing press 10 according to the present embodiment, a print having excellent image formability can be obtained.

In the offset printing press 10 according to the present embodiment, it is preferable to apply post-processing after the offset printing step S1 and the UV irradiation step S2 have been successively performed. That is, after offset printing and UV irradiation, post-processing is preferably performed. In this case, a print having excellent decorativeness can be obtained.

Examples of post-processing include silk screen printing, flexographic printing, roller coating, painting, molding and the like.
Among these, post-processing is preferably silk screen printing. In this case, a print having excellent decorativeness can be obtained. In this case, since the printing speeds of offset printing and silk screen printing can be made to coincide with each other, offset printing (offset printing step S1 and UV irradiation step S2) and silk screen printing can be performed successively.

The present invention is used as a printing method using an offset printing press for applying a UV curable ink to a substrate. According to the printing method using the offset printing press of the present invention, a print having excellent formability of an image can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Ink conveyance roll group 1a ... Temperature control ink conveyance roll 2 ... Waterless version 3 ... Blanket 4 ... Guide 5 ... UV irradiation machine 6 ... conveyance roll 8 ... · Printed material 10 ··· Offset printing machine S1 · · · Offset printing process S2 · · · UV irradiation process

Claims

A plurality of transport rolls for transporting a substrate, a blanket adjacent to the transport rolls, a waterless plate adjacent to the blanket, a group of ink transport rolls adjacent to the waterless plate, and the printed substrate And a UV irradiator for irradiating the body with UV.
An offset printing step of printing a UV curable ink applied to the waterless plate onto the substrate after transferring the UV curable ink onto the blanket;
A UV irradiation step of irradiating the printed substrate with UV to cure the UV curable ink;
Have
The traveling speed of the printing material is 1700 m / h or less,
A printing method using an offset printing press in which the film thickness of the UV curable ink to be applied is 3 to 7 μm.
The printing method using an offset printing press according to claim 1, wherein the traveling speed of the printing medium is 250 m / hour to 1700 m / hour.
The printing method using the offset printing press according to claim 1 or 2, wherein the printing material is non-water absorbent synthetic paper, plastic film or paper board.
The ink transport roll group includes a temperature control ink transport roll for adjusting the temperature of the UV curable ink.
The printing method using an offset printing press according to any one of claims 1 to 3, wherein hot water is circulated through the core portion of the temperature control ink transport roll.
The temperature at the time of use of the UV curable ink is adjusted to 20 ° C. to 50 ° C., and the viscosity at the time of use of the UV curable ink is set to 5 Pa · s to 1500 Pa · s by the temperature control ink transport roll. A printing method using the offset printing press according to claim 4.
The printing method using the offset printing press according to any one of claims 1 to 5, wherein a U-shaped guide is provided below the transport roll so as to conform to the shape of the transport roll.
The printing method using the offset printing press according to claim 6, wherein air is blown between the transport roll and the guide so as to prevent the printing medium from hanging down.
The printing method using the offset printing press according to any one of claims 1 to 7, wherein after offset printing and UV irradiation are performed, post-processing is performed.
The printing method using an offset printing press according to claim 8, wherein the post-processing is silk screen printing.