KR102337559B1 - Flexographic printing plate - Google Patents

Abstract

Provided is a flexographic printing plate that does not cause problems such as uneven shading in the transferred ink even when the transfer operation is performed at short intervals, and can efficiently transfer with quick repetition.
In the state wound around the outer periphery of the plate body of the flexographic printing machine, the ink on the surface of the anilox roll is held on the upper surface of the ink holding convex part 2a of the resin plate 2, and on the held convex part 2a A flexographic printing plate (1) for transferring ink to a printed surface by contact with an object (workpiece), wherein both edges (2e) before and after the printing direction of the convex portion (2a) are in contact with the anilox roll It is characterized in that it is formed as a downwardly tapered surface to relieve the impact.

Description

Flexo printing plate {FLEXOGRAPHIC PRINTING PLATE}

The present invention relates to a resin-made flexographic printing plate used in a flexographic printing machine.

Flexographic printing uses a flexible (flexible) flexographic printing plate (hereinafter simply referred to as “printing plate”) made of resin or rubber in which convex portions (images and characters, etc.) for holding ink are patterned on the surface, and retaining the ink It is a printing method in which the ink held on the upper surface (top surface) of the convex part is transferred to the to-be-printed object with low printing pressure. In this flexographic printing, the ink holding convex portion of the printing plate is relatively flexible and can be followed on the surface of a printed object of various shapes, so it is used for printing with a printed material having various materials and thicknesses (for example, patents). See Document 1 et al.).

3 is a schematic configuration diagram showing a general configuration of a flexographic printing machine, and FIG. 4 is (a) a plan view (top view), (b) side view, and (c) main part of the flexographic printing plate used in the flexographic printing method. It is an enlarged schematic diagram. In addition, in all the drawings, white arrows indicate the "printing direction" of the printing plate (rotational direction on the plate body).

As shown in FIG. 3, the flexographic printing machine (rotary type) includes a plate body 10 for winding and mounting the printing plate 5, and an anilox roll for attaching ink to the printing plate 5 (anilox roll) ( 20) and a doctor (blade) 30, ink replenishment means (ink tank 40), and a flat plate-shaped printed object (work (W)) the plate body 10 (printing plate) (5)) It is comprised mainly by the moving stage 50 etc. which are made to move in parallel in synchronization with the rotation.

In addition, the flexographic printing plate (printing plate 5) used in the flexographic printing machine has a substantially rectangular shape that can be wound around the plate body 10 in a plan view as shown in FIGS. 4 (a) and (b). A substrate 3 such as a film made of polyethylene terephthalate (PET) which is formed of and supports the pulling (tension) when wound around the plate body 10, and a resin plate 6 formed (laminated) thereon. is done

In the central portion of the resin plate 6, as shown in Fig. 4 (b), on a flat base 6b (non-printing portion) not involved in printing, a printing convex portion 6a for holding ink; 6a, . Fixing parts 6d and 6d used for attachment to the plate body 10 are provided at the ends with relatively thin bent parts 6c and 6c interposed therebetween.

Each of the printing convex portions 6a constituting the print pattern is usually produced by a resin curing method using photolithography, and as shown in an enlarged schematic diagram in FIG. 4(c), each printing projection 6a Each part (edge 6e) in the printing direction (longitudinal direction) of is formed in a relatively sharp shape (so-called "angular linear shape").

In addition, a plate body mounting jig such as a vise (4A, 4B) (double-dotted line) is attached to each of the fixing portions 6d and 6d at both ends in the longitudinal direction, and using a fastener such as a pin or a hook, As shown in FIG. 3 , in a state in which the tension in the circumferential direction is slightly applied to the entire plate, the printing plate 5 is configured to be kept in close contact with the periphery (outer periphery) of the plate body 10 .

And, in the flexographic printing, the ink supplied on the anilox roll 20 from the ink tank 40 and the amount of which is adjusted by the doctor (blade) 30 comes into contact with the printing plate 5 (synchronous rotation). ), each convex portion 6a of the printing plate 5 is held at the top of each of the printing patterns (the printing convex portions 6a, 6a, ...) 10) By lightly contacting (key-touching) the object (workpiece W) on the moving stage 50 moving horizontally in synchronization with the rotation of 10), it is transferred to the surface (printed surface) of this work W.

Japanese Patent Publication No. 4917693

However, in the transfer (printing) method using the flexographic printing plate as described above, the impact (contact pressure) to the transfer target surface is weak and does not damage the surface of the printed object (workpiece). It is used in the manufacturing process of solar panels, etc. In these manufacturing processes, an electrode layer, a sealing layer, a masking layer, etc. are formed by flexographic printing using an organic solvent-based ink (coating solution) on the surface (processing surface) of a flat glass substrate. It has been adopted, and in recent years, an increase in its efficiency (speed) has been studied.

However, in order to improve the transfer efficiency (processing speed) using the flexographic printing, when the transfer operation is continuously performed at a short interval (cycle time or tact time), the surface of the transferred workpiece (processing It became clear that "light-dark nonuniformity" of the coating liquid of the work flow direction (printing direction) generate|occur|produced on the target surface). According to detailed observation, this shading non-uniformity is due to fluctuations in the amount of ink applied (adhering) and the coating thickness in the printing direction (shaking). or in the form of moire).

The present invention has been made in view of these circumstances, and even when the transfer operation is performed at short intervals, problems such as uneven shading in the transferred ink do not occur, and a flexographic printing plate capable of efficiently transferring quickly and repeatedly. is for that purpose.

In order to achieve the above object, the flexographic printing plate of the present invention includes a plate-shaped base in which attachments to the plate body are formed at both ends before and after the printing direction of the printing plate, and a convex part for holding ink formed on the base along a predetermined printing pattern. In a state of being wound around the outer periphery of the plate body of the flexographic printing machine, the ink on the surface of the anilox roll is held on the upper surface of the ink holding convex portion, and the held ink is brought into contact with the printed body to the printed surface. As a flexographic printing plate to be transferred to a flexographic printing plate, the edge portions before and after the printing direction of the convex portion are formed in a downward “‡” tapered surface to alleviate the contact impact with the anilox roll.

The inventor of the present invention, while repeating research to solve the above problems, the cause of the "shade unevenness" of the coating solution is the impact generated when the printing plate (each ink holding convex portion) on the plate body comes into contact with the anilox roll , found that the printing plate (plate body) was at a point where periodic oscillation (wavy rotation) occurred. In addition, if the transfer interval (tact time) of flexographic printing is shortened, "periodic vibration of the printing plate (plate body)" generated in the previous transfer process is "transfer from the printing plate to the object (workpiece)" of the ink once. It was discovered that the procedure was not carried out alone, and that it had an effect on the transfer process of the next round.

In order not to generate periodic vibration of the printing plate (plate body) or to converge quickly, a method of reducing the hardness of the entire printing plate to alleviate the contact impact (collision) with the anilox roll is considered. However, when durability (printing resistance) is considered, a balance of hardness (hardness) to a certain degree is also required, so that the hardness of the entire printing plate including the convex portion for printing cannot be arbitrarily lowered. So, the present inventors came up with the idea of mitigating the impact when the flexographic printing plate and the anilox roll are in contact by the shape of the plate, and as described above, the ink that first contacts (contacts) the anilox roll in the flexographic printing plate. By making the "edge shape of the convex part" for holding|maintenance into a tapered shape, it discovered that the said impact can be alleviated significantly, and arrived at this invention.

That is, in the flexographic printing plate of the present invention, the edges of the ink holding convex portion formed on the flat base in the printing direction before and after are formed in a tapered shape (downward tapered surface), and this downward tapered surface is an anilox roll first contact with the With this configuration, the first impact when the flexographic printing plate comes into contact with the anilox roll is alleviated, and the generation of vibrations caused by the impact can be suppressed. In addition, even when the tapered edge portions of each of the ink holding convex portions are in contact with (transferred) the printed surface of the object, it is possible to suppress the occurrence of an impact due to the contact in the same manner as above. Therefore, in the flexographic printing plate of the present invention, by their synergistic effect, the occurrence of "shade unevenness" of ink caused by periodic vibration (wave rotation) of the printing plate (plate body) during ink holding and transferring is prevented, The ink (coating solution) can be accurately applied (transferred) to the required pattern and to the same thickness as the design. In addition, since there is no occurrence of "shading unevenness" of the ink, it becomes possible to continuously perform transfer at a short transfer interval (tact time).

In addition, among the flexographic printing plate of the present invention, the inclination angle of the downward taper surface is set to 0.01 to 30° downward from the horizontal in a state in which the printing plate is arranged on a horizontal plane, when in contact with the anilox roll. The initial shock is more moderated, and the occurrence of vibration resulting from this shock and occurrence of unevenness in the shading of the ink at the time of transfer can be reliably prevented.

1 is a (a) plan view and (b) side view of a flexographic printing plate according to an embodiment of the present invention.
Fig.2 (a)-(d) is a schematic diagram which showed the example of the shape of both edge parts (corners) of the convex part for printing in all in the flexographic printing board of embodiment of this invention.
3 is a schematic configuration diagram showing a general configuration of a flexographic printing press.
Figure 4 is a schematic view showing the shape of both edges (corners) of the flexographic printing plate of the prior art (a), (b) a side view, and (c) a convex part for printing.

EMBODIMENT OF THE INVENTION Next, embodiment of this invention is described in detail based on drawing. In addition, since the structure and function of the flexographic printing machine used in the following embodiment are also the same as the general flexographic printing machine shown in FIG. 3, the same code|symbol as FIG. 3 is attached|subjected and the detailed description is abbreviate|omitted. In addition, in the drawings of the present embodiment, the thickness of the flexographic printing plate is emphasized so that the shape of the details can be easily understood.

The flexographic printing plate (printing plate 1) in this embodiment is formed by a photolithography method using a photocurable (photosensitive) resin, as in the conventional example, as shown in Fig. 1(a). , Polyethylene terephthalate (PET), which is formed in a substantially rectangular shape that can be wound around the plate body 10 in a plan view (see Fig. 1 (a)) and supports the pulling (tension) when wound around the plate body It is comprised from the base material 3, such as a film made, and the resin board 2 formed (laminated) on it.

In addition, in the central portion of the resin plate 2, as shown in Fig. 1 (b), similar to the conventional example, to hold the ink on the flat base 2b (non-printing part) not involved in printing. The printing convex portions 2a, 2a, ... for At the ends (in the left-right direction in the drawing), fixing portions 2d and 2d used for attachment to the plate body 10 are provided with relatively thin bent portions 2c and 2c interposed therebetween.

The printing plate 1 is different from the conventional printing plate 5 in that each printing convex part 2a (ink holding convex part) constituting the printing pattern of the printing plate 1 is shown in FIG. As shown in the enlarged schematic diagrams of a) to (d), the edge portion 2e of each convex portion 2a for printing in the printing direction (longitudinal direction) (the portion indicated by the mesh-shaped hatching in Fig. 1) is, The point is that it is formed as a downwardly inclined surface (downward taper surface) with a relatively gentle gradient angle. This is a characteristic of the flexographic printing plate in this embodiment.

The shape of the edge portion 2e (downward tapered surface) of each of the convex portions 2a for printing will be described in more detail. , in a state in which the printing plate 1 is horizontally arranged, the edge portion 2e of the convex portion 2a gradually becomes thinner at an inclination angle α toward the outside of the edge portion. It is formed with a directional slope. In addition, the inclination angle (taper angle) (α) of the downward taper surface is usually 0.01 to 30°, preferably 0.5 to in consideration of the collision with the anilox roll 20 after being mounted on the plate body 10 . It is set within the range of 20°.

In addition, the range (distance L from the cross-section) of the downward inclined surface of the edge part 2e is usually in the range of 1 to 8 mm, preferably in the range of 3 to 5 mm, and the convex part ( 2a) The amount of drooping (distance H) from the upper surface (top surface) is usually set to 0.05 to 0.5 mm, preferably 0.1 to 0.25 mm. In addition, in the example of Fig. 2(a), the inclination angle α is 10°, the range of the downward taper surface (distance L from the cross-section) is 5 mm, and the upper surface (top of the convex portion 2a) is It is designed with an inclined surface of 0.25 mm (distance H) from the surface).

In addition, the tapered shape of the edge part 2e of the said convex part 2a is good also as a downward-curving R-shape as shown in FIG.2(b), FIG.2(c) ) as shown in the figure, it is good also as an intaglio shape (concave shape). In addition, the tapered shape of the edge portion 2e does not necessarily have to be formed in one step, and as shown in FIG. α) is within the range of 0.01 to 30°) or a complex curved surface such as a gothic arch may be formed.

As a material constituting the flexographic printing plate (printing plate 1), a material having constant elasticity even after plate forming, such as resin or rubber, is used. In addition, the printing plate 1 in this embodiment transfers an organic solvent-based ink such as an electrode layer, a sealing agent, and a masking agent onto a substrate (work W) in a manufacturing process of liquid crystal, organic EL, organic TFT, etc. Since it is used for forming, it is determined in consideration of the degree of swelling of the resin and the like, depending on the type of the organic solvent contained in the ink used in the process, the plate cleaning liquid, and the like.

In addition, the photolithography method is preferably used for manufacture of the printing plate 1 . In this case, as a material constituting the printing plate 1, a photosensitive (photocurable) resin composition is used, and among them, urethane-based, polyester-based, polybutadiene-based prepolymers, acrylate oligomers, The photosensitive resin which consists of a mixture of an acrylate monomer, a photoinhibitor, a photoinitiator, etc. is used preferably.

In addition, the external dimensions of the printing plate 1 depend on the size of the substrate (workpiece W) or the plate body 10 to be printed, but generally the printing direction (longitudinal direction of the printing plate 1) is 300 to About 2300 mm, the width direction (the horizontal direction of the printing plate 1) is about 500-2800 mm. In addition, the printing direction (vertical direction) length of the relatively thin curved portion 2c is set to about 0 to 100 mm, and the printing direction (vertical direction) length of the fixed portion 2d is set to about 15 to 40 mm.

In addition, the hardness of the printing convex portion 2a of the printing plate 1 is preferably set in the range of 35 to 70 degrees JIS rubber hardness Shore A. When the Shore A hardness is less than 35 degrees, the printing convex portion 2a is too soft with respect to the substrate (workpiece W) and is deformed at the time of printing, and there is a tendency that high-precision printing cannot be maintained. Conversely, when the Shore A hardness of the flexographic printing plate exceeds 70 degrees, there is a tendency to damage the surface of the substrate (workpiece W) or the electrodes or wiring formed on the surface.

In addition, the film-like substrate 3 positioned on the back side of the printing plate 1 is formed by laminating one or two or more layers of resin films (or sheets), and in this example (FIG. 1), polyethylene terephthalate A two-layer film made from (PET) is used. As resin forming the film-like base material 3, other resins, such as polypropylene (PP) and polyvinyl chloride (PVC), can also be used. In addition, as the total thickness of the film-like base material 3 alone, a film having a thickness of about 0.1 to 0.5 mm is used, and the total thickness of the fixing portion 2d including the end of the printing plate 1 is 1.5 to 3.0. It is adjusted so that it becomes about mm.

According to the flexographic printing plate of the above configuration, since the edge portions 2e and 2e of the convex portion 2a for printing before and after the printing direction are formed with a tapered surface inclined downward, the printing plate 1 is not an anilox roll 20 The initial shock when in contact with the Thereby, the generation of vibrations in the printing plate 1 or the plate body 10 due to the impact is suppressed, and the occurrence of “shading unevenness” in the ink generated after transfer can be prevented in advance. In addition, since flexographic printing using the flexographic printing plate does not cause problems such as "shading unevenness" of the ink, transfer can be efficiently and continuously performed with a short transfer interval (tact time).

The flexographic printing plate of the present invention can be suitably used for printing (transfer formation) of an electrode layer installed on a substrate such as liquid crystal, organic EL, organic TFT, or a sealing agent, a masking agent, etc. can contribute

1: Printing plate 2: Resin plate
2a: convex part 2b: base
2c: bent part 2d: fixed part
2e: (convex part) edge part 3: base material
4A. 4B: vise 5: printing plate
6: resin plate 6a: convex part
6b: base 6c: bend
6d: fixed part 6e: edge (convex part)
10: plate body 20: anilox roll
30: Doctor 40: Ink Tank
50: moving stage W: work
H: Load amount (distance) L: Distance from the end (range of taper)
α: angle of inclination

Claims (2)

It consists of a flat base in which attachments to the plate body are formed on both ends of the printing plate before and after the printing direction, and convex parts for holding ink formed on the base according to a predetermined printing pattern, wound around the outer periphery of the plate body of the flexographic printing machine. In the state, the ink on the surface of the anilox roll is maintained on the upper surface of the convex portion for retaining the ink, and the held ink is transferred to the surface to be printed by contact with a printed object, wherein the hardness of the convex portion is JIS rubber hardness Shore A is set in the range of 30 to 70 degrees, the edges before and after the printing direction of the convex part are formed as a downward tapered surface to relieve the contact impact with the anilox roll, and the retained ink is The flexographic printing plate held on the upper surface of the convex portion for retaining the ink including the direction tapered surface. The method of claim 1,
A flexographic printing plate in which the inclination angle of the downward taper surface is set to 0.01 to 30° downward from the horizontal in a state in which the printing plate is arranged on a horizontal plane.

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