JP2779829B2 - Gravure coating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gravure coating method, and particularly to the production of cards such as driver's licenses and ID cards, when performing resin lamination for surface protection. An effective gravure coating method.

[Conventional technology]

In a driver's license, an ID card, and the like, a laminate of a transparent plastic film for protecting the printing surface is known. In the production, predetermined items are usually printed or photo-sensitized printed on the surface of the card base material, inserted between the laminated film sheets, and then obtained by thermocompression bonding.

On the other hand, among the roll coating methods, a gravure coating method is known. In the roll coating method, the coating liquid is scraped off with a blade in order to regulate the coating film thickness. As a blade in this case, usually, a phosphor bronze plate is often used, but a plastic blade is also used.

[Problems to be solved by the invention]

However, as mentioned above, when manufacturing cards,
The number of manufacturing steps increases, and the manufacturing cost increases. In addition, there is a problem that air bubbles are mixed into the lamination surface during lamination.

Therefore, in order to reduce the manufacturing cost, it is desirable to apply the resin directly to the card base material and laminate it one by one.

In this case, in order to protect a display surface such as printing on the surface of the card base material, a film thickness of 10 μm or more is required as a protective layer. Therefore, in the roll coating method, coating is generally performed while passing a sheet between a pair of rubber rolls. However, with a normal rubber roll, coating with such a film thickness cannot be performed. The present inventors have found that it is effective to apply.

On the other hand, in such a gravure coating method, when the above-mentioned plastic blade is used in place of the conventional phosphor bronze plate, the gravure roll surface has irregularities, so the tip of the blade is severely worn, and maintenance must be frequently performed. , And the replacement frequency must be shortened.

Therefore, a main object of the present invention is to provide a gravure coating method capable of reducing the wear rate of a plastic blade, improving maintainability, and reducing the cost of a plastic blade to be used by increasing the frequency of replacement. It is in.

[Means for solving the problem]

The above object is to transfer the applied coating liquid to the surface of the gravure roll in the process of passing the material to be coated between the gravure roll and the back roll facing the gravure roll, and apply the coating liquid to the surface of the material to be coated. When applying with a gravure roll and scraping excess coating liquid on the surface of the gravure roll with a plastic blade, the direction of the arrangement of the blade from the base end to the tip end is opposite to the rotation direction of the gravure roll. This can be solved by bending the blade so that at least 1 mm of the front surface of the gravure roll facing surface contacts the gravure roll surface and pressing the blade against the gravure roll surface side.

[Action]

According to the present invention, when the blade is bent and pressed toward the gravure roll surface side so that 1 mm or more of the tip of the gravure roll facing surface contacts the gravure roll surface, the contact area with the gravure roll surface increases. Therefore, as shown in the experimental examples described later, the wear becomes slow.

In particular, even when the blade is arranged in a reverse system in which the direction from the base end to the front end is opposite to the rotation direction of the gravure roll, the wear is extremely slow. In this respect, the case of FIG. 5 shown in comparison is in contrast to the fact that the abrasion is extremely fast because of the reverse method, in addition to the factor that only the tip contacts.
Therefore, maintainability is improved and material cost is reduced.

In addition, various experimental results show that there is no decrease in scraping property and coating property even when the plastic blade is bent and pressed against the gravure roll surface under the reverse method.

On the other hand, as described above, when laminating an ID card, as described later, directly laminating a transparent resin on a card base material that has been cut into a desired size in advance, the manufacturing process is simplified, and the manufacturing cost is greatly reduced. This is effective in reducing the number of bubbles and eliminating the incorporation of bubbles.

At this time, if a gravure roll is used as an application roll in order to increase the thickness of the target protective layer, an application thickness of 10 μm or more can be obtained. In this respect, it is effective to employ a gravure coating method.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings.

First, an example of the apparatus of the present invention will be described with reference to FIGS. 1 and 2, and thereafter, a means for bending a plastic blade used for regulating the thickness of a coating solution in coating will be described.

FIG. 1 is an overall front view of the apparatus of the present invention, in which each device or member shown is housed in one housing 1. A base plate 2 having a flow-down hole 2a is provided on the upper part of the housing 1. Cards (base materials) 3 made of plastic such as PET are arranged, for example, vertically, and one card is sequentially arranged from the arranged group. Each is moved vertically to the position of the flow-down hole 2a, and flows down from the flow-down hole 2a. Below the downflow hole 2a, as shown in detail in FIG.
A letter-shaped guide distribution body 4 is provided.

By rotating the pivot 4A forward or backward by a cylinder (not shown), for example, the guide sorting body 4 is oriented in the direction of the solid line in FIG. 1 for a normal card, and is oriented in the direction of the imaginary line in the figure for an abnormal card. It has become. The card 3 that has fallen from the downflow hole 2a is guided along the web portion 4B of the guide sorting body 4.

A guide plate 5 is arranged below the guide distribution body 4 as necessary. Furthermore, a pair of push rollers 6A and 6B made of rubber or the like are provided to face each other below. At least one, and preferably both, of the pushing rolls 6A and 6B are used as driving rolls.

Below the press rolls 6A and 6B, an application device 7 for applying a laminated resin made of, for example, an ultraviolet curable resin is provided. The coating device 7 includes a coating resin vat 70 of a laminating resin, a pickup roll 71 of the coating liquid, a gravure roll 72 in contact therewith, a back roll 73 opposed thereto, and a plastic blade for a doctor for scraping off the coating liquid of the gravure roll 72. 74, a coating liquid tank 75, a supply pump 76 for supplying a coating liquid to the vat 70 therefrom, a vat
A recovery liquid tank 77 for recovering the overflow liquid from 70 is provided.

The card 30 having one surface coated with the laminating resin by the coating device 7 is dropped onto a conveyor 8 horizontally arranged below the coating device 7 and coated with the protective layer 31.
It is conveyed to the left in FIG. 1 with the surface facing up. An ultraviolet irradiation device 9 having one or a plurality of ultraviolet lamps 9A is provided above the conveyor 8 to irradiate the surface of the card 30 coated with the laminated resin with ultraviolet light.

On the exit side of the conveyor 8 is a stocker 10 for the final product.
Is provided. Reference numeral 11 denotes a scraping plate that scrapes off excess laminating resin at the tail end of the card 30 provided as necessary.

In the laminating apparatus thus configured, the uncoated card 3 flows down from the flow-down hole 2a, is guided by the guide distribution body 4 between the press rolls 6A and 6B, and is bitten therein. Next, by pushing rolls 6A and 6B,
The card 3 is guided between the gravure roll 72 and the back roll 73. Here, the nip position of the pushing rolls 6A and 6B,
Since the distance between the nip positions of the gravure roll 72 and the back roll 73 is preferably set to be shorter than the length of the card 3 in advance, the pushing force of the pushing rolls 6A and 6B causes
Card 3 is gravure roll 72, back roll
Supplied between 73.

In the coating device 7, the coating liquid is transferred from the pickup roll 71 to the gravure roll 72, and the ultraviolet curable resin is applied to one surface of the card 3. The coated card 30 is conveyed by the conveyor 8 and is irradiated with ultraviolet rays from the ultraviolet irradiation device 9 in the process, whereby the laminated protective layer 31 is cured. The cured card 30 of the protective layer 31 is temporarily stored in the stocker 10.

The plastic blade 74 used in the present invention is used by being bent as shown in FIG.

FIG. 5 shows an embodiment in which a plastic blade 74 is brought into contact with the gravure roll 72 by a conventional method. As can be immediately inferred from FIG. 5, and as described above, the tip of the blade 74 wears extremely fast.

On the other hand, in the present invention, for example, as shown in FIG. 3, the base of the holder 50 holding the base side of the blade 74 is used as a pressing body by using the fixing plate 51 fixed to the gantry as a base. By pushing the blade 74 with the bolt 52, the tip of the blade 74 is bent, and the entire side surface of the gravure roll 72 at the tip can be brought into contact with the gravure roll 72. The imaginary line in FIG. 3 shows a state in which the blade 74 is located according to the conventional example.

In this case, the leading edge of the blade 72 does not contact,
Preferably, there is a contact portion slightly from the base side. FIG. 4 is an enlarged view of the contact mode. The circumferential length l of the contact portion is preferably at least 1 mm, usually at least 2.5 mm. In addition, a gravure roll 72 and a blade 74
The contact portion of the blade 74 desirably follows the tangent line L at the position of the leading edge of the blade.

As the plastic blade, a blade made of a plastic material such as polyester, acrylic, or vinyl chloride can be used. The thickness of the blade 74 is 200-800
It is preferably about μm.

On the other hand, in the above example, a hard metal roll such as a stainless steel roll is used as the back roll. In this case, if the surface is a hard metal, the internal material is not limited. The diameter of the back roll is 100mm, especially 3
0 mm or less is preferable. As the gravure roll 72,
Its diameter is 100mm, desirably 60mm, particularly preferably 40m
m or less. The nip pressure is 100-800k
g, desirably 200-700 kg, particularly preferably 300-600 kg
It is said. "Prescale" manufactured by Fuji Photo Film Co., Ltd. can be used for measuring the nip pressure.

In the above example, the reason why the metal gravure roll 72 is selected is that it is effective when the laminate film thickness is large. By the way, in the present invention example, as the laminate film thickness,
It is preferably from 5 to 100 μm, particularly preferably from 10 to 30 μm. However,
For a smooth rubber roll, the thickness is at most 5 μm.
It is desirable that the surface of the gravure roll 72 is subjected to hard chrome plating.

As the material of the card base material, a plastic sheet such as polyethylene terephthalate (PET), acrylic, or the like, a composite sheet of plastic and another material, paper, or the like can be used. The thickness of the card substrate is 200
10001000 μm, particularly preferably 350-750 μm.

 The coating speed is preferably from 0.3 to 5 m / min.

By the way, in the above apparatus example, the pickup roll
The rotation direction of 71 is set to the solid line direction when the coating liquid hardly foams, and is set to the virtual line direction when the coating liquid easily foams. Accordingly, in the present invention, the relative position between the gravure roll 72 and the plastic blade 74 may be a trailing method in addition to a reverse method as shown in FIG.

As the above-mentioned laminate resin, an ultraviolet curable resin is preferably used. As the ultraviolet curable resin, all known ones can be used.

The ultraviolet curable resin basically contains a photopolymerizable prepolymer, a photopolymerizable monomer, and a photopolymerization initiator. If necessary, a sensitizer, a pigment, a filler, an inert organic polymer, a leveling agent, a thixotropic agent, a thermal polymerization inhibitor, a solvent, and the like are added.

(Experimental example) A 500 μm PET sheet was used as a card substrate, and an epoxy-based UV-curable resin was used as the target film thickness of 15 μm
In the case of applying with a gravure roll of the laminating apparatus, a 550 μm polyester plastic blade is used without bending as shown in FIG.
Replacement was required by abrasion in about 16 hours, but according to the present invention, when the contact portion length was 1.5 mm and the blade was applied while being bent, continuous use was possible for about 180 hours.

〔The invention's effect〕

As described above, according to the present invention, the cost of the plastic blade used can be reduced by reducing the wear rate of the plastic blade, improving the maintainability, and increasing the frequency of replacement.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a laminating apparatus as an application example of the present invention, FIG. 2 is a perspective view of a guide distributing body, FIG. 3 is a state in which a plastic blade is flexed and pressed, FIG. FIG. 5 is a view showing the arrangement of the conventional blades. 2a: Downflow hole, 3: Card, 4: Guide distributing body 6A, 6B: Push roll, 7: Coating device 8: Conveyor, 9: Ultraviolet irradiation device 10: Stocker, 72 ... Gravure roll 73… Back roll, 74… Plastic blade, 50
... Holder, 52 ... Bolt for pressing

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B05D 1/28 B05D 3/00 B05D 5/06 B05C 1/02 102 B05C 1/08-1/12

Claims (1)

(57) [Claims] In the process of passing a material to be coated between a gravure roll and a back roll opposed thereto, the picked-up coating liquid is transferred to the surface of the gravure roll, and the coating liquid is transferred to the surface of the coated material. While applying with the gravure roll, when scraping the excess coating liquid on the gravure roll surface with a plastic blade, the arrangement of the blade is such that the direction from the base end to the tip end is opposite to the rotation direction of the gravure roll. Wherein the blade is bent such that 1 mm or more of the front end abdominal surface of the gravure roll facing surface contacts the gravure roll surface, and is pressed against the gravure roll surface side. Gravure coating method.