JP2013123836A - Letterpress printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a letterpress printing apparatus having little mixture of foreign matter in a continuous printing matter, and capable of performing high quality printing with no unevenness by reducing ink accumulation on a doctor roll.SOLUTION: A letterpress printing apparatus includes: a resin letterpress on which a printing pattern is formed; a cylinder-like plate cylinder for mounting the letterpress thereon; an anilox roll supplying ink to the letterpress; an ink chamber supplying ink onto the anilox roll; the doctor roll scraping off excessive ink on the anilox roll; an ink suction nozzle sucking ink accumulated on the doctor roll; a circulation device for recycling the sucked ink; and a surface plate for placing printed matter.

Description

  The present invention relates to a relief printing apparatus for forming a functional thin film with high quality.

  In recent years, attempts have been made to use a known printing method that is excellent in mass productivity and can reduce the manufacturing cost in forming a fine thin film pattern. In particular, in the display field, in order to cope with an increase in screen size and cost, studies are being made on patterning functional thin films such as organic semiconductors and conductive materials by printing methods.

  As specific printing methods, offset printing, gravure printing, gravure offset printing, letterpress printing, and the like have been studied.

  Among these various printing methods, the resin relief printing method using a relief printing plate made of resin, in particular, includes the relief printing plate, an ink supply roll in which fine recesses (cells) are engraved on the surface called an anilox roll, and a solvent-dried ink It is a printing method consisting of the above, and has been widely used for printed materials such as wrapping paper. This resin relief printing method is particularly suitable for forming a thin film having a thickness of about 0.01 to 0.2 μm.

  In addition, since the resin relief printing method can be printed at a very low printing pressure called kiss touch, it can be applied to a glass substrate or a substrate on which a transparent electrode or the like whose characteristics are easily destroyed by applying high pressure is formed. It is also suitable for printing, and is a printing method particularly suitable for pattern formation of electronic parts such as displays.

Hereinafter, a general relief printing apparatus 200 will be described with reference to FIG.
The relief printing apparatus 200 includes an anilox roll 201 having a cell for supplying ink to the plate surface of the relief plate 204, an ink chamber 208 for supplying ink to the anilox roll, and a relief plate 204 for pattern formation via an under-cushion cushion 203. Is equipped with a rotary plate cylinder 205 on which a printing substrate 207 is mounted, a substrate surface plate 206 on which a substrate 207 to be printed is placed, and a doctor blade 202 that performs doctoring to scrape off ink.

Next, the flow of printing when using the relief printing apparatus 200 of FIG. 2 will be described.
First, after the substrate to be printed 207 is placed on the substrate surface plate 206, it moves to just below the plate cylinder 205. When the substrate surface plate 206 moves, the plate cylinder 205 rotates synchronously with the operation of the substrate surface plate 206, and ink is supplied to the relief plate 204 from the anilox roll 201 operating at the same speed as the plate cylinder 205. Immediately after the ink is supplied to the relief plate 204, the ink on the relief plate is transferred to the printing substrate 207 and the printing operation is completed.

  Here, the doctor blade 202 is pressed against the anilox roll at a pressure of about 20 kPa in order to uniformly push the ink into the anilox roll cell by scraping off excess ink from the ink applied on the anilox roll 201. For this reason, both the anilox roll and the doctor blade are worn, and there is a problem that the scraped portion is mixed into the ink.

  Since the anilox roll 201 and the doctor blade 202 are generally made of a metal oxide or a resin, they are mixed into the ink as foreign matters. Foreign matter mixed in the ink finally remains in the printed film.

  This foreign matter is not a major problem if it is a general printed matter that has been the main target of conventional resin relief printing, but it is intended for fine patterning of functional thin films such as organic semiconductor thin films and organic EL thin films. In the printing for electronics members, the product is defective due to the scraped foreign matter. In particular, when the foreign material is a metal, a problem such as short-circuiting occurs due to electrical conduction, and it is necessary to reduce the foreign material.

  As described above, the doctor blade is mainly used as a means for scraping off the ink on the anilox roll. However, as shown in Patent Document 1, a doctor roll technique using a rubber roll as a doctor is also used as another means. Has been.

  By using the doctor roll method, it is possible to suppress the generation of foreign matter as generated by the doctor blade method, but this method uses the ink slightly deposited on the doctor roll when printing continuously. As the amount increases, the amount of deposition increases and the in-plane film thickness becomes uneven.

JP 2001-083495 A

  In view of the above-mentioned problems, the present invention provides a relief printing apparatus capable of high-quality printing without unevenness by reducing contamination of foreign matter in a continuous printed product and reducing ink accumulation on a doctor roll. There is to do.

  In order to solve the above problems, the present inventors conducted extensive research, and as a result, doctoring failure occurred when doctoring was performed continuously using a doctor roll. It has been found that this is due to the occurrence of unevenness in the ink scraping on the anilox roll.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention provides at least a resin-made relief plate on which a printing pattern is formed, a cylindrical plate cylinder on which the relief plate is mounted, and supplies ink to the relief plate. An anilox roll, an ink chamber that supplies ink to the anilox roll, a doctor roll that scrapes off excess ink on the anilox roll, an ink suction nozzle that sucks ink deposited on the doctor roll, and A letterpress printing apparatus comprising a circulation device for reusing ink and a surface plate on which a substrate is placed.

  The invention according to claim 2 is the relief printing according to claim 1, wherein the doctor roll and the ink suction nozzle are not in contact with each other, and the ink suction nozzle has a slit nozzle shape. Device.

  The invention according to claim 3 is the relief printing apparatus according to claim 1 or 2, wherein the slit width of the ink suction nozzle is 0.1 mm to 1 mm.

  The invention according to claim 4 is characterized in that the installation position of the nozzle tip of the ink suction nozzle is within a range of 90 ° or less in the rotational direction from the contact position of the anilox roll and the doctor roll. The relief printing apparatus according to any one of claims 1 to 3.

  The invention according to claim 5 is the relief printing according to any one of claims 1 to 4, wherein a clearance between the ink suction nozzle and the doctor roll is 0.01 mm to 0.5 mm. Device.

  The invention according to claim 6 is characterized in that the circulation device comprises an ejector recovery tank, a recovery pump, a liquid feed pump, a prefilter, a filter, and a viscosity adjusting device. The letterpress printing apparatus described in 1.

  By using the relief printing apparatus of the present invention, it is possible to provide a functional material having a uniform functional thin film with no foreign matter contained in the printed matter and without any unevenness.

It is a cross-sectional schematic diagram of the relief printing apparatus which shows one Embodiment of this invention. It is a cross-sectional schematic diagram of a conventional relief printing apparatus.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that. The present invention is not limited to this.

FIG. 1 is a schematic sectional view of a relief printing apparatus 100 showing an embodiment of the present invention. In particular, an ink supply mechanism comprising an anilox roll 101 will be mainly described.
A relief printing apparatus 100 shown in FIG. 1 has a cylindrical plate cylinder 105 on which a resin relief plate 104 for pattern formation is mounted, an anilox roll 101 that supplies ink in contact with the relief plate 104, and supplies ink to the anilox roll. An ink chamber 108, a doctor roll 102 for scraping off excess ink on the anilox roll 101, an ink suction nozzle 110 for sucking ink deposited on the doctor roll, a circulation device 120 for reusing the sucked ink, And a letterpress printing apparatus comprising a positioning surface plate 106 on which a printing material 107 onto which the letterpress ink is transferred is placed.

  An anilox roll 101 that can be used in the relief printing apparatus 100 of the present invention is a ceramic obtained by patterning a chromium oxide film formed by plasma spraying chromium oxide on a core roll made of a SUS material by laser engraving. Either a roll or a core roll, after copper plating is applied, a resin is applied, laser patterning is performed, and then a corrosion treatment is performed. Any pattern such as a helical pattern, FM pattern, honeycomb pattern, diamond pattern, or dot pattern can be used as the pattern formed on the anilocle roll.

These patterns may be appropriately angled to prevent moire.
After these patterns are formed, the surface of the anilox roll 101 is desirably polished to prevent scratching the doctor roll 102 side. Specifically, it is desirable that the anilox roll pattern is polished so as to eliminate protrusions of 4 μm or more.

  As a mechanism for rotating the anilox roll 101, it is desirable to perform direct drive with a servo motor capable of controlling rotation with high accuracy because uneven rotation speed greatly affects printed matter. Further, when using a speed reduction mechanism to obtain the required torque, it is desirable to use a backlashless mechanism.

  Next, as a doctor roll 102 that can be used, a core roll made of SUS material, etc., nitrile rubber, silicone rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, acrylonitrile rubber, ethylene propylene A rubber, urethane rubber, or the like may be wound around the rubber roller, or a PFA heat shrinkable tube wound around these rubber rollers may be used. These rubber materials are selected from the resistance to the solvent used as the ink.

  The surfaces of these rubber rolls preferably have an arithmetic surface roughness Ra of 0.1 μm or less and a maximum height Rz of 1 μm or less. By satisfying these conditions, a low dust generation and smooth doctoring surface can be obtained.

Next, as the hardness of the doctor roll 102 used in the relief printing apparatus 100 of the present invention, any can be used in the range of 30 ° to 70 ° in JIS-A hardness.
As the mechanism for rotating the doctor roll 102, since the rotational speed unevenness has a large influence on the printed matter, it is desirable to use a servo motor that can control the rotation with high accuracy and to perform the direct drive. It is desirable to have a system that can be controlled in a synchronously rotatable manner.

Next, an actual operation when the relief printing apparatus 100 is used will be described.
After placing the glass substrate 107 on the substrate surface plate 106, a printing operation is started by a print start instruction.

  During this time, ink is supplied onto the anilox roll 101 and doctoring is continuously performed, so that a smooth doctored surface is always held. The speed at the time of doctoring can be arbitrarily selected in the region where the doctoring is stable.

Next, the ink suction nozzle 110 will be described.
The shape is preferably a slit nozzle that can be sucked uniformly in the width direction. Unevenness generated on the doctor roll 102 accumulates, and unevenness is caused in the scraping of the excess ink on the anilox roll 101, causing a transfer failure. Therefore, the slit width of the ink suction nozzle 110 is preferably 0.1 mm to 1 mm. If it is this range, it can attract | suck uniformly with respect to the lump size of the ink deposited on the doctor roll 102.

  Further, the ink suction nozzle 110 is used in a non-contact position with the doctor roll 102, so that there is no foreign matter generation source compared to a contact system such as an ink wiping roll of the doctor roll 102, and a function represented by an organic EL thin film or the like. In the printing for electronic members for the purpose of fine patterning of a thin film, the cause of scraped foreign matter can be reduced.

  Further, the clearance between the ink suction nozzle 110 and the doctor roll 102 is a distance between 0.01 mm and 0, which is sufficiently in contact with the droplets attached to the doctor roll 102 and causes capillary action between the doctor roll 102 and the ink suction nozzle 110. A range of .5 mm is desirable.

  As a suction method, there is a pump by mechanical motion, and an ejector that can obtain suction directly from compressed air. However, the ejector 111 that can obtain suction directly from compressed air has no foreign matter mixed, and the suction pressure is 0. 01 Mpa to 0.1 Mpa is desirable. If the suction force is smaller than this, the liquid cannot be sufficiently recovered, and ink residue remains, resulting in unevenness. On the other hand, if the suction pressure is large, when the ink is a volatile solvent, drying is promoted, resulting in unevenness.

The installation position of the ink suction nozzle 110 is a position close to the contact position because the ink adhering to the doctor roll 102 is sucked in a wet state before drying.
It is desirable to be within a range of 90 ° in the rotational direction from the contact point of 02 and the aniloc roll 101. When the installation position of the ink suction nozzle 110 exceeds 90 °, drying of a part of the ink occurs and ink suction becomes insufficient.

  Further, in order to prevent aggregation and fixation due to drying of the ink, the solvent may be applied and redissolved, and the ink may be collected by the ink suction nozzle 110. At that time, as a form of the solvent coating nozzle, a spray such as a one-fluid nozzle, a two-fluid nozzle, a pulse jet, or a slit nozzle may be used, but a cover or a local exhaust is installed in order to prevent scattering of the cleaning liquid. There is a need. Further, it is desirable that the ink suction nozzle 110 is sucked at a position close to the solvent coating portion so that the solvent does not drip on the doctor roll after the solvent is coated.

  The circulation device 120 according to the present invention is a device that regenerates the ink collected from the ink suction nozzle 110 and circulates it to the ink chamber 108, and includes an ejector collection tank 111, a collection pump 112, a prefilter 114, a filter 115, a viscosity. An adjustment device 113 is used.

  Since the ink sucked by the ink suction nozzle 110 can be returned to the ink chamber 108 by the circulation device 120 and reused, the functional thin film can be formed using expensive ink typified by organic semiconductors and conductive materials. In forming, the effect of greatly improving the ink utilization efficiency can be obtained.

  Specifically, it is reused by the circulation device 120 in the following circulation cycle. That is, the ink is sucked by the ink suction nozzle 110 and then collected by the pre-filter 114 while removing large ink aggregates in the ejector collection tank 111. Next, the ink is collected from the ejector collection tank 111 to the viscosity adjusting device 113 by the collection pump 112. The liquid flows in, and the viscosity is adjusted by dropping the solvent. The liquid is then sent to the ink chamber 108 through the filter 115 by the liquid feed pump 116 and reused.

  The ejector recovery tank 111 includes a vacuum ejector tank, a steam ejector, and a water ejector, and a vacuum ejector tank is desirable from the viewpoint of mixing moisture in the ink.

  The recovery pump 112 supplies liquid from the ejector recovery tank 111 to the viscosity adjusting device 113 and may be any of a piston pump, a diaphragm pump, and a plunger pump, but is selected according to the solvent of the ink to be used and the target viscosity. The The liquid feed pump 115 performs liquid feed from the viscosity adjusting device 113 to the ink chamber 108, and may be any of a piston pump, a diaphragm pump, and a plunger pump, depending on the solvent of the ink used and the target viscosity. Selected.

  The pre-filter 114 is installed to remove large aggregated solid ink, and the filter 115 is preferably a finer one than the pre-filter. The material of the pre-filter 114 filter 115 is selected according to the resistance to ink.

  The viscosity adjusting device 113 has a shape for accumulating ink, and is provided with a viscometer, a stirring device, and a solvent dropping device, and feedbacks the ink based on the result of measuring the viscosity of the ink in the ink chamber 108. Since the timing of dropping can be automatically controlled, the viscosity of the ink in the system can be controlled below the upper limit of the viscosity to be controlled by setting the value of the viscosity that gives a command signal for solvent dropping.

Next, after the substrate surface plate 106 is moved directly below the plate cylinder, ink is transferred from the anilox roll 101 onto the plate, and then printing is performed on the glass substrate 107 placed on the substrate in synchronization with the rotation of the plate cylinder. The surface speed of the anilox roll when transferring ink from the anilox roll 101 onto the plate may be equal to the doctoring speed, but if the doctoring speed is low, the transfer takes time, so the transfer speed is increased. Also good. However, when the transfer speed is increased, it is necessary to adjust the transfer start position so that a stable doctoring surface is transferred to the plate.
By performing the above operation, a high-quality printed material can be obtained.

  Examples of the present invention will be described below. In addition, this invention is not limited to an Example, The improvement, deformation | transformation, etc. in the range which can achieve this invention do not deviate from the meaning of this invention.

<Example 1>
Printing was performed on a glass plate using the polymer organic light-emitting material described below by the relief printing apparatus shown in FIG.

<Anilox roll pattern formation>
A chrome plating roll having a surface length of 200 mm was used as the anilox roll. On the anilox roll, a square cell having a side of 65 μm was formed at a pitch of 72.5 μm and inclined by 60 ° from the roll horizontal line. In addition, the said pattern was formed over 180 mm on the surrounding surface of the anilox roll.

<Doctor roll>
As a doctor roll, urethane rubber having a hardness of JIS-A 50 ° was wound around a SUS core and processed into a cylindrical shape. A PFA (perfluoroalkoxy fluororesin) heat-shrinkable tube was wound on the processed urethane rubber roll, and then polishing was carried out so that Ra was 0.05 μm and Rz was 1 μm.

  The doctor roll was installed in the form of pushing in by 50 μm with respect to the anilox roll. The installed anilox roll and doctor roll are each driven by a servo motor.

<Ink suction nozzle>
As the ink suction nozzle, a slit nozzle made of material SUS304 having a slit width of 180 × 1 mm that can be sucked uniformly in the width direction was used. The clearance with the doctor roll is 0.5 mm, and the liquid is installed between the doctor roll and the slit nozzle at a position where sufficient liquid capillaries occur. Further, the tip of the nozzle was installed at a position of 90 ° from the contact point between the anilox roll and the doctor roll, and suction was performed at a constant pressure of 0.05 MPa using an ejector.

<Production of letterpress with resin>
A black oil-based dye was applied to the surface of a SUS304 plate having a thickness of 0.2 mm as a reflection suppressing layer by a die coating method so as to have a thickness of 1.5 μm. A negative photosensitive resin mainly composed of polyamide was applied to the surface of this laminate so that the total thickness was 100 μm, and a relief printing base was obtained.

Next, a chrome mask having a negative pattern (effective area opening 106 μm * 100 mm, non-opening space 392 μm * 100 mm, total number of effective lines 400, size W 200 mm L100 mm) drawn on the base of the letterpress plate Was used to expose a 50 μm proximity gap. After the exposure, development was performed while pouring warm water to produce a relief plate having a height of the convex portion of 90 μm, a line width of the convex portion of 106 μm, and a space of 392 μm. The produced relief plate was affixed to the plate cylinder of the relief printing apparatus using a printing cushion tape having a thickness of 0.5 mm.

<Ink>
An organic light-emitting ink was prepared by dissolving a polyphenylene vinylene derivative, which is a high-molecular organic light-emitting material, in anisole so as to have a concentration of 2%. When the viscosity of the prepared ink was measured, it was 60 mPa · s, and the surface tension was 34 mN / m. Thereafter, the ink was put into the chamber of the relief printing apparatus.

<Circulating device>
Ink suction nozzle, ejector collection tank, prefilter, filter, viscosity adjusting device, each device is connected by a Teflon (registered trademark) tube with a diameter of φ4, and the prefilter uses a 0.45μm membrane filter of 1μm membrane filter did.

  As the recovery and liquid feed pump, a diaphragm pump which is sealless and excellent in quantitativeness was used, and a pump having quantitativeness with anisole solvent resistance and a viscosity of 60 mPa · s was used.

  The viscosity adjusting device is equipped with a dropping device linked to a magnetic stirrer and a vibratory viscometer in a liquid storage tank made of SUS304, and the anisole is fed back to the liquid storage tank by feeding back the signal from the value of the viscometer. The viscosity was adjusted in the range of 60 mPa · s to ± 5 mPa · s.

<Printing>
Printing was performed on 300 mm sq. 0.7 mm thick soda glass using the above apparatus, plate, and luminescent material ink. Printing was performed at a cycle time of 60 s, the doctoring speed was 10 mm / s, the printing speed was 100 mm / s, and 50 sheets were printed continuously.

<Comparative Example 1>
Printing was carried out in the same manner as in Example 1 except that no ink suction nozzle was installed.

<Comparative example 2>
Printing was performed in the same manner as in Example 1 except that the urethane rubber was wound around the doctor roll.

<Comparative Example 3>
Printing was performed in the same manner as in Example 1 except that the ink suction nozzle was set at 90 ° or more.

<Evaluation>
The printed materials and doctor roll surfaces obtained in Example 1 and Comparative Examples 1 to 3 were evaluated as follows, and the results are shown in Table 1.
1. Foreign matter contamination to determination by microscopic confirmation ○: No abnormality ×: Foreign matter confirmation Printing unevenness ~ Judgment by visual confirmation ○: No abnormality ×: Foreign matter confirmation

<Comparison result>
As a result of continuous printing of 50 sheets, the product of the present invention obtained in Example 1 was free from printing unevenness of the printed matter, contamination of the doctor roll and contamination, and good results were obtained. On the other hand, the printed matter obtained in Comparative Example 1 was confirmed to have unevenness due to ink accumulation (aggregates) and unevenness due to poor doctoring on the 10th sheet. In Comparative Example 2, foreign matter due to scraping and unevenness due to ink aggregates were observed on the 38th sheet, and foreign matter was confirmed on the 45th sheet. Furthermore, in Comparative Example 3, unevenness of the ink aggregate due to drying on the doctor roll was confirmed on the 33rd sheet.

DESCRIPTION OF SYMBOLS 100 Letterpress printing apparatus 101 Anilox roll 102 Doctor roll 103 Under-cushion cushion 104 Letterpress 105 Plate cylinder 106 Substrate plate 107 Substrate 108 Ink chamber 110 Ink suction nozzle 111 Ejector collection tank 112 Viscosity adjustment apparatus 113 Collection pump 114 Pre Filter 115 Filter 116 Liquid feed pump 120 Circulating device 200 Conventional letterpress printing device 201 Anilox roll 202 Doctor blade 203 Plate cushion 204 Letter plate 205 Plate cylinder 206 Substrate platen 207 Printed substrate 208 Ink chamber

Claims (6)

  At least a resin relief plate having a printing pattern formed thereon, a cylindrical plate cylinder on which the relief plate is mounted, an anilox roll for supplying ink to the relief plate, an ink chamber for supplying ink to the anilox roll, and the anilox A doctor roll that scrapes off excess ink on the roll, an ink suction nozzle that sucks ink deposited on the doctor roll, a circulation device for reusing the sucked ink, and a surface plate on which a substrate is placed A letterpress printing apparatus.   2. The relief printing apparatus according to claim 1, wherein the doctor roll and the ink suction nozzle are not in contact with each other, and the ink suction nozzle has a slit nozzle shape.   The relief printing apparatus according to claim 1 or 2, wherein a slit width of the ink suction nozzle is 0.1 mm to 1 mm.   The installation position of the nozzle tip of the ink suction nozzle is in a range of 90 ° or less in the rotational direction from the contact position of the anilox roll and the doctor roll. The letterpress printing apparatus described.   The relief printing apparatus according to any one of claims 1 to 4, wherein a clearance between the ink suction nozzle and the doctor roll is 0.01 mm to 0.5 mm.   The relief printing apparatus according to any one of claims 1 to 5, wherein the circulation device includes an ejector recovery tank, a recovery pump, a liquid feed pump, a prefilter, a filter, and a viscosity adjusting device.