JP2011020407A - Manufacturing method of uneven pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate by which high definition printed matter can be prepared, in a manufacturing technique of a printing plate including a process of forming a pattern by laser engraving. <P>SOLUTION: This is a manufacturing method of a printing plate including a laser engraving process in which a resin layer is engraved using laser. The laser engraving process is such that the resin layer is engraved with the output of 20-80% of the maximum output of the laser, with 50-1,000 W, and with the number of lines of 120 lpi or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a concavo-convex pattern in which pattern formation is performed by laser engraving.

In recent years, so-called flexographic printing has been widely used as a printing method for soft packaging materials such as paper and film. For example, various packaging materials such as corrugated cardboard, paper containers, paper bags, and soft packaging films, wallpaper, decorative plates, and the like. As a printing method for building materials and labels, its specific gravity is increasing.
In order to produce a printing plate for flexographic printing, a photosensitive resin (a liquid resin or a solid resin plate formed into a sheet shape) is usually used.
Specifically, after placing a predetermined photomask on the photosensitive resin, irradiating with light through the mask, causing the photosensitive resin to undergo a crosslinking reaction, the unexposed portion that has not undergone the crosslinking reaction is washed away with a developer, A method of producing a printing plate on which a pattern is formed is used.
In recent years, a thin light-absorbing layer called a black layer is provided on the surface of a predetermined photosensitive resin plate, and this is irradiated with laser light to form a mask image directly on the photosensitive resin plate, and light is transmitted through the mask image. A flexo CTP (Computer to Plate) technique, which is an efficient method for producing a printing plate in which a crosslinking reaction is performed by irradiation, and then a non-crosslinked portion is washed away with a developer, has been developed.

However, even in this flexo CTP technology, since a developing process is essential in the printing plate preparation process, further efficiency in the manufacturing process is required.
As a method for producing a printing plate that does not require a development step, there is a method in which a resin layer is directly engraved with a laser to form a pattern.
In this technique, a laser engraving plate is used as a plate material, and there are advantages such as shortening of plate making time and reduction of waste.
In the following Patent Document 1, a printing plate from which engraving debris generated in a laser engraving process is removed, which is a two-point convex part and a concave character, a 30 μm-wide thin line, an independent point of a diameter of 100 μm, and 156 lpi, 1% A laser engraving printing plate in which halftone dots are formed is disclosed.

JP 2008-105429 A

The technique disclosed in Patent Document 1 is a printing plate from which engraving residue generated in a laser engraving process is removed, and has two points of convex portions and concave characters, a thin line of 30 μm width, and an independent point of a diameter of 100 μm. In addition, there is a description of a laser engraving printing plate in which 156 lpi and 1% halftone dots are formed.
However, no consideration has been given to print quality, particularly high-definition print reproduction, and there is still much room for improvement from this point of view.

  Accordingly, an object of the present invention is to provide a high-density concavo-convex pattern in a concavo-convex pattern manufacturing technique including a step of performing pattern formation by laser engraving. Furthermore, an object of the present invention is to provide a method for producing a printing plate capable of excellent print quality, particularly high-definition printing reproduction.

Accordingly, the present inventors have intensively studied on a method for producing a concavo-convex pattern in order to solve the above-described problems of the prior art, and as a result, the present invention has been completed. That is, the present invention is as follows.
A method for producing a concavo-convex pattern including a laser engraving process for engraving a resin layer using a laser, wherein the laser engraving process has an output of 20% to 80% of a maximum output of a laser to be used, and is 50 W or more and 1000 W In the following, a method for producing a concavo-convex pattern, which is a step of engraving a resin layer with a line number of 120 lpi or more.

  ADVANTAGE OF THE INVENTION According to this invention, a high-density uneven | corrugated pattern can be provided in the manufacturing technology of the uneven | corrugated pattern including the process of forming a pattern by laser engraving. Furthermore, according to the present invention, a printing plate capable of high-definition printing reproduction can be provided.

The dot gain curve obtained from Examples 1-5. The dot gain curve obtained from Comparative Examples 1-5.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. In addition, this invention is not limited to the following description, In the range of the summary, various deformation | transformation can be implemented.

[Method of manufacturing uneven pattern]
The present embodiment is a method for producing a concavo-convex pattern including a laser engraving process, wherein the laser engraving process has an output of 20% to 80% of the maximum output of the laser, and is 50 W or more and 1000 W or less, and It is a manufacturing method of the uneven | corrugated pattern which is the process of engraving a resin layer with the number of lines more than 120 (lpi) ((number of lines per inch)).

  In this embodiment mode, laser engraving is performed at 50 W to 1000 W. When laser engraving is performed at such a power, a high-density concavo-convex pattern can be clearly formed.

In the present embodiment, an output of 50 W or more and 1000 W or less is obtained by using 20 to 80% of the maximum output of the laser to be used. Considering simply the productivity of laser engraving, usually the maximum output of the laser, ie 100% output, is used. However, according to the inventor's research, engraving with an output of 20 to 80% of the maximum output of the laser without using the maximum output can be formed with high reproducibility even with a high-density uneven pattern. found. That is, even when laser engraving is performed at the same 300 W power, for example, when 100% output of a laser with a maximum output of 300W is performed and when 60% output of a laser with a maximum output of 500W is performed, high density unevenness It was found that there was a difference in the reproducibility of the pattern, and laser engraving of a high-density concavo-convex pattern, which is usually difficult, could be realized with good reproducibility if performed at 60% output of a laser with a maximum output of 500 W.
And, when such a concavo-convex pattern manufacturing method is applied to the production of a printing plate, it is possible to produce a printing plate that does not cause a density jump when dot gain plotting and can obtain a high-quality printed matter. became.
The laser output in the laser engraving process is 20% to 80% of the maximum output of the laser, preferably 20% to 75%, more preferably 25% to 72%, and even more preferably 30% to The output is 70%. Within this range, laser engraving can be performed stably.

  The density of the concavo-convex pattern created by the laser engraving process is 120 lpi or more, preferably 125 lpi or more, more preferably 133 lpi or more. Within this range, it can be regarded as a high-definition printed matter.

The resolution of data used for the laser engraving (hereinafter also referred to as “engraving original data”) is preferably 100 dpi (number of dots per inch) to 5000 dpi, more preferably 100 dpi to 5000 dpi. By setting it in this range, a concavo-convex pattern in which the shadow and highlight are balanced can be obtained.
An AM screen is usually used for the arrangement of dots in the engraving source data pixels, but an FM screen or a hybrid combining them may be used.

The laser used for laser engraving is not particularly limited as long as the applied resin layer includes a wavelength having absorption.
Specifically, an infrared or infrared emitting solid laser such as a sealed carbon dioxide laser, a flow-through carbon dioxide laser, a YAG laser, or a semiconductor laser can be cited as a suitable laser.
In addition, the second harmonic of a YAG laser having an oscillation wavelength in the visible light region, a copper vapor laser, an ultraviolet laser having an oscillation wavelength in the ultraviolet region, such as an excimer laser, and a YAG laser that has been wavelength-converted to the third or fourth harmonic are: It is a laser capable of ablation processing that cuts the bonds of organic molecules, and is a laser suitable for performing fine processing.

The laser irradiation described above may be continuous irradiation or pulse irradiation.
There is no limitation on the atmosphere for performing laser engraving on the resin layer. For example, laser engraving can be performed in an oxygen-containing gas, generally in the presence of air or in an air stream, but may be performed in the presence of carbon dioxide gas or nitrogen gas.
After completion of laser engraving, the powdered or liquid substance generated uses a predetermined method, for example, a method of cleaning with water containing a solvent or a surfactant, a strong alkaline electrolyzed water, a high-pressure spray, etc. Or by irradiating with high-pressure steam.

In the laser engraving process, a desired image can be set as digital data, and a predetermined image can be used to perform laser engraving using a laser device for engraving to form a relief image on the resin layer.
The laser engraving may be performed in a plurality of times, and the same light source or different light sources may be used for the plurality of times of engraving.

Specifically, the laser engraving can be performed using a known technique, for example, a technique described in JP-A-2001-146064.
Specifically, first, the block data created by a block forming device such as a computer is read into a laser engraving control device via a floppy disk (registered trademark), MO disk, CD, DVD, portable hard disk, LAN, etc. . Subsequently, the control device analyzes the composition data in accordance with the machining control program, creates an execution file, and instructs the resin layer to start engraving. Subsequently, the resin layer is engraved by outputting a laser to a portion corresponding to the concave portion of the printing original plate.
In addition, as a laser used for the laser engraving process, a laser having a plurality of laser heads, a laser having a function of dividing a single laser, an engraving machine having a function of simultaneously engraving a plurality of places with software, and the like are used. This can shorten the number of manufacturing steps of the concavo-convex pattern and improve the manufacturing efficiency.

  The engraving speed of the resin layer during the laser engraving is preferably 2 m / s or more and 18 m / s or less. Here, the engraving speed refers to the scanning speed of the laser in the main scanning direction. More preferably, they are 2 m / s or more and 17 m / s, More preferably, they are 2 m / s or more and 16 m / s. If it is this range, a resin layer can move stably.

  The laser engraving feed pitch is preferably 5 μm or more and 20 μm or less. Here, the engraving feed pitch means that when the original forming the concave / convex pattern is cylindrical or fixed in a cylindrical shape, when the original or the cylindrical original is rotated once, the laser head of the laser is This means the distance moved in the sub-scanning direction. Also, when the original plate is a flat plate or fixed to a flat surface (flat bed), when the laser head moves to the next row after engraving the previous row, the laser head moves in the sub-scanning direction. Means the distance to move. The engraving feed pitch is more preferably 7 μm or more and 18 μm, and still more preferably 10 μm or more and 15 μm. Within this range, dots can be stably formed. In this case, the laser may be either a type of engraving machine in which the workpiece is movable in the sub-scanning direction or the laser head is movable in the sub-scanning direction.

It is preferable that the maximum output of the laser is 60 W or more and 1200 W or less. More preferably, they are 100W or more and 800W or less, More preferably, they are 150W or more and 700W or less. Within this range, the productivity and stability of laser engraving can be maintained.
Regarding the output of the laser, for example, the laser emitted from the laser head, the field mate (trade name, manufactured by Coherent, USA) which is a laser power meter display, and the power sensor PM5K (trade name, manufactured by Coherent, USA) It can be measured by combining them.

  When the concavo-convex pattern is a printing plate, the height of each convex part constituting the halftone dot part having an area ratio of 1% of the resin layer engraved by the laser is 10 μm or more and 150 μm or less lower than the height of the solid printing part. It is preferable. This range varies depending on the hardness of the resin layer, the printing press, the printing ink, the printing medium, the printing plate, that is, the cushion layer and the support, etc., more preferably 10 μm to 100 μm, still more preferably 10 μm to 80 μm. It is. This range is suitable for high-definition printing.

[Resin layer]
In the present embodiment, the resin layer is not particularly limited as long as the concave portion can be formed by irradiation with a laser, and examples thereof include a thermoplastic resin layer and a cured layer of a curable resin composition, and laser engraving. From the viewpoint of properties, a cured product layer of a curable resin composition is preferable. Examples of the cured product layer of the curable resin composition include a thermoset product layer of a thermosetting resin composition and a photocured product layer of a photosensitive resin composition. The thickness of the resin layer can be arbitrarily selected according to the intended use of the concavo-convex pattern, and is preferably 0.1 to 7 mm.

[Thermoplastic resin layer]
The thermoplastic resin layer that is a specific example of the resin layer may be an elastomer or a non-elastomer.
Although it does not specifically limit as a thermoplastic elastomer, SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-polystyrene), SBR which are styrenic thermoplastic elastomers. (Styrene-butadiene rubber) and the like, olefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, ester-based thermoplastic elastomer, amide-based thermoplastic elastomer, silicone-based thermoplastic elastomer, and the like. The thermoplastic elastomer is a material that flows by heating and can be molded like a normal thermoplastic, and exhibits rubber elasticity at room temperature. The molecular structure consists of soft segments such as polyether or rubber molecules, and hard segments that prevent plastic deformation at around room temperature, as with vulcanized rubber. The hard segments include frozen phase, crystalline phase, hydrogen bonding, and ionic crosslinking. There are various types.

  The type of thermoplastic elastomer can be selected depending on the use of the uneven pattern. For example, urethane, ester, amide, and fluorine thermoplastic elastomers are preferred in fields where solvent resistance is required, and urethane, olefin, ester, and fluorine heat are required in fields where heat resistance is required. A plastic elastomer is preferred. Moreover, hardness can be changed greatly with the kind of thermoplastic elastomer. When the uneven pattern produced in the present embodiment is used as a normal printing plate, the Shore A hardness is preferably in the range of 20 to 75 degrees, and the uneven pattern is formed on the surface of paper, film, building material, etc. When used for embossing to form, a relatively hard material is required, and it is preferable to have a Shore D hardness of 30 to 80 degrees.

As non-elastomeric, there is no particular limitation, but polyester resin, unsaturated polyester resin, polyamide resin, polyamideimide resin, polyurethane resin, unsaturated polyurethane resin, polysulfone resin, polyethersulfone resin, polyimide resin, polycarbonate Examples thereof include resins and wholly aromatic polyester resins.
The softening temperature of the thermoplastic resin is preferably 50 ° C. or higher and 500 ° C. or lower, more preferably 80 ° C. or higher and 350 ° C. or lower, and further preferably 100 ° C. or higher and 250 ° C. or lower. If the softening temperature is 50 ° C. or higher, it can be handled as a solid at room temperature, and a sheet or cylinder processed can be handled without deformation. When the softening temperature is 500 ° C. or lower, it is not necessary to heat to a very high temperature when processing into a sheet or cylinder, and it is not necessary to alter or decompose other compounds to be mixed. In this embodiment, the softening temperature is measured by using a dynamic viscoelasticity measuring device. When the temperature is increased from room temperature, the viscosity changes greatly (the slope of the viscosity curve changes). Let temperature be the softening temperature.

[Thermosetting material layer of thermosetting resin composition]
As a thermosetting material of a thermosetting resin composition, the thermosetting material of the resin composition which mixed the polymerizable monomer with the said thermoplastic elastomer is said, for example. Specific examples of the thermoplastic elastomer that can be used here include SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), and SEBS (polystyrene-polyethylene / polybutylene-polystyrene), which are styrenic thermoplastic elastomers. Olefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, ester-based thermoplastic elastomer, amide-based thermoplastic elastomer, silicon-based thermoplastic elastomer, fluorine-based thermoplastic elastomer, and the like.

[Photocured layer of photosensitive resin composition]
The resin (a) constituting the photosensitive resin composition is not particularly limited as long as it is cured by light irradiation. The range of the number average molecular weight is preferably 1000 or more and 500,000 or less, more preferably 2000 or more and 300,000 or less, and further preferably 5000 or more and 100,000 or less. If the number average molecular weight is 1000 or more, sufficient mechanical strength to withstand use as a printing plate when cured is obtained, and if it is 500,000 or less, it can be sufficiently decomposed by laser beam irradiation. Can do. In the present invention, the number average molecular weight is measured using Gel Permeation Chromatography (GPC) and is evaluated with respect to a polystyrene sample having a known molecular weight.
From the viewpoint of laser engraving properties, styrene, acrylic esters, methacrylic esters, ester compounds, ether compounds, nitro compounds, aliphatic cyclic compounds, etc. as monomer units that are easily decomposed in the molecular chain of the resin (a) Is preferably included. Especially polyethers such as polyethylene glycol, polypropylene glycol, polytetraethylene glycol, aliphatic polycarbonates, polymethyl methacrylate, polystyrene, nitrocellulose, polyoxyethylene, polynorbornene, polycyclohexadiene hydrogenated, or branched structure Many resins such as dendrimers are representative examples of those that are easily decomposed. As an index for measuring the ease of decomposing the resin, there is a weight reduction rate measured using thermogravimetric analysis under air. The weight reduction rate of the resin (a) used in the present invention is preferably 50 wt% or more at 500 ° C. If it is 50 wt% or more, the resin can be sufficiently decomposed by irradiation with a laser beam.

The photosensitive resin composition may contain an organic compound having an unsaturated bond that participates in radical polymerization reaction or ring-opening polymerization reaction. Examples of such organic compounds include olefins such as ethylene, propylene, styrene, and divinylbenzene, acetylenes, (meth) acrylic acid and derivatives thereof, haloolefins, unsaturated nitriles such as acrylonitrile, (meth) Acrylamide and its derivatives, allyl compounds such as allyl alcohol and allyl isocyanate, unsaturated dicarboxylic acids such as maleic anhydride, maleic acid, fumaric acid and itaconic acid and their derivatives, vinyl acetates, N-vinylpyrrolidone, N-vinyl Examples thereof include carbazole and cyanate esters.
Moreover, the photosensitive resin composition may contain other additives, such as a photoinitiator and a stabilizer.

[Dye / Pigment]
In general, since the resin material has absorption in the vicinity of 10 μm of the carbon dioxide laser, it is not essential to add a component that assists in the absorption of laser light to the resin layer. However, the YAG laser has a wavelength in the vicinity of 1.06 μm, and there are not many resins having absorption for the laser having such a wavelength. Therefore, when a YAG laser is used for laser engraving, it is preferable to add a dye or a pigment to the resin layer as a component that aids absorption.
Specific examples of dyes include poly (substituted) phthalocyanine compounds, metal-containing phthalocyanine compounds, cyanine compounds, squarylium dyes, chalcogenopyrylarylidene dyes, chloronium dyes, metal thiolate dyes, bis (chalcogenopyrrillo) polymethine dyes, oxyindolizine dyes Bis (aminoaryl) polymethine dyes, merocyanine dyes and quinoid dyes.
Specific examples of pigments include dark inorganic pigments such as carbon black, graphite, copper chromite, chromium oxide, cobalt chrome aluminate, copper oxide and iron oxide; metal powders such as iron, aluminum, copper and zinc; and These metals may be doped with Si, Mg, P, Co, Ni, Y or the like.
The above dyes and pigments may be used alone or in combination of two or more, and when the resin layer is composed of a plurality of photosensitive resin layers, the dye and content contained in each layer May be different.
However, when there is a step of curing the photosensitive resin composition using light in the production process of the resin layer, addition of organic / inorganic compounds (dyes and pigments) having a large light absorption at the wavelength of light used for photocuring The amount is preferably in a range that does not hinder the production of the resin layer. When the photosensitive resin composition is photocured to form a resin layer, the total addition ratio of the dye and the pigment to the total amount of the photosensitive resin composition is preferably 5% by mass or less, and more preferably 2% by mass or less. Note that this is not the case when the curable resin composition is thermally cured to form a resin layer, or when the resin layer is not cured by light or heat.

The resin layer may have a single layer structure, or may have a structure in which a plurality of materials having different compositions are stacked. For example, a layer that can be engraved using a laser having an oscillation wavelength in the near infrared region such as a YAG laser, a fiber laser, or a semiconductor laser is formed on the outermost surface, and an infrared laser such as a carbon dioxide laser is formed below the layer. Alternatively, a layer capable of laser engraving using a visible / ultraviolet laser may be formed. By adopting such a laminated structure, a relatively rough pattern is deeply engraved using an extremely high output carbon dioxide laser, and an extremely fine pattern is formed near the surface by a near infrared laser such as a YAG laser or a fiber laser. Can be engraved using. The fine pattern in the vicinity of the surface only needs to be relatively shallow and can be engraved. Therefore, the thickness of the layer sensitive to the near infrared laser is preferably in the range of 0.01 mm to 0.5 mm.
As described above, by stacking the layer sensitive to the near infrared laser and the layer sensitive to the infrared laser, the depth of the pattern engraved using the near infrared laser can be accurately controlled. This is because a phenomenon that makes it difficult to engrave a layer sensitive to an infrared laser with a near infrared laser can be used.
Note that the difference in the fineness of the pattern can be controlled due to the difference in the oscillation wavelength inherent to the laser device, that is, the difference in the diameter of the laser beam that can be reduced.
When performing laser engraving by this method, you may use a laser engraving device equipped with an infrared laser and a near-infrared laser, respectively, or use a laser engraving device equipped with both an infrared laser and a near-infrared laser. May be.

Hereinafter, specific examples and comparative examples will be described in detail.
In the following, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.

[Production Example] Preparation of Resin Layer Into a 1 L separable flask equipped with a thermometer, a stirrer, and a reflux condenser, polycarbonate diol “PCDL T4672” (trademark) manufactured by Asahi Kasei Chemicals Corporation (number average molecular weight 2025, OH value 55.4). ) 402.60 g and 24.01 g of tolylene diisocyanate were added and stirred at 80 rpm for about 1 hour under heating at 40 ° C. Then, 0.2 g of dibutyltin dilaurate was added as a catalyst and reacted for 3 hours. .
Next, 11.53 g of 2-methacryloyloxyisocyanate is added and further reacted for about 3 hours, and the terminal is a methacrylic group (the average number of polymerizable unsaturated groups in the molecule is about 2.0 per molecule). A resin layer forming resin (a) having a number average molecular weight of about 7500 was prepared.
This resin (a) was in the form of a syrup at 20 ° C., flowed when an external force was applied, and did not recover its original shape even when the external force was removed.
The following organic compound, photopolymerization initiator, stabilizer and the like were mixed with 100 parts by mass of the resin (a) to prepare a resin composition for forming a resin layer.
As organic compounds, 37.3 parts by mass of phenoxyethyl methacrylate “Light Ester PO” (trademark) manufactured by Kyoeisha Chemical Co., Ltd. and diethylene glycol monobutyl ether monomethacrylate “Light Ester BC” (trademark) 11.9 manufactured by Kyoeisha Chemical Co., Ltd. Part by mass was used.
As a photopolymerization initiator, 3.0 parts by mass of 2,2-dimethoxy-2-phenylacetophenone, which is a decay type photopolymerization initiator, and 0.8 parts by mass of benzophenone, which is a hydrogen abstraction type photopolymerization initiator, were used.
As stabilizers, 0.9 parts by mass of 2,6-di-t-butyl-4-methylphenol and 1.5 parts by mass of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate used.
As additives, 1.5 parts by mass of silicone oil “KF-410” (trademark) manufactured by Shin-Etsu Chemical Co., Ltd., an inorganic porous material “Syrosphere C-1504” (trademark) manufactured by Fuji Silysia Chemical Ltd. (number average) Silo which is a porous spherical silica having a particle diameter of 4.5 μm, a specific surface area of 520 m ² / g, an average pore diameter of 12 nm, a pore volume of 1.5 mL / g, a loss on ignition of 2.5% by mass, an oil absorption of 290 mL / 100 g. The sphericity of Sphere C-1504 was observed with a scanning electron microscope, and almost all particles were 0.9 or more).
This produced the liquid resin composition at 20 degreeC.

Next, a fiber-reinforced plastic sleeve (trade name “Polyflex RUBIN”, manufactured by POLYWEST, Germany) having an inner diameter of 152.905 mm, an outer diameter of 155.880 mm, and a width of 1000 mm was prepared as a support.
Cushion tape (trademark “Duploflex 5.3” manufactured by Lohmann, Germany) is pasted on the support, and the resin composition for forming the resin layer prepared as described above is applied thereon with a doctor blade. did.
Thereafter, the metal halide lamp (trade name “M056-L21” manufactured by Eye Graphics Co., Ltd.) was irradiated with 12000 mJ / cm ² (energy amount accumulated using a UV meter and a UV-35-APR filter), and cured. Thus, a resin layer was formed to obtain a printing original plate (a laminate of a support and a resin layer).
The outermost surface of the resin layer was adjusted by grinding and polishing so that the printing peripheral length after curing was 500 mm to obtain a printing original plate for printability evaluation.
Ten printing original plates were produced by the same method.

(1) Engraving image The engraving image was created to include the following shapes.
For the halftone dots, patterns of 20%, 25%, 30%, 40%, 50%, 60%, 70%, and 80% were created.
Separately, a gradation pattern from 0% to 100% was created.
The fine lines produced patterns with a width of 30 μm, 60 μm, 100 μm, 150 μm, 200 μm, 250 μm, and 500 μm.
The white lines produced patterns with a width of 30 μm, 60 μm, 100 μm, 150 μm, 200 μm, 250 μm, and 500 μm.
The fine characters are 2 points, 3 points, 4 points, 6 points, and 8 points in Mincho and Gothic.
White thin letters were created in 2 points, 3 points, 4 points, 6 points, and 8 points in Mincho and Gothic.

(2) Relief depth When the relief depth is set large, the area of the relief surface of the fine halftone dot pattern cannot be secured, and the shape collapses and becomes unclear, so the relief depth is set to 0.5 mm.
“Relief depth” means a difference in height between a printing portion (relief surface) and a non-printing portion (back surface) of a printing plate.

(3) Laser engraving A 2540 dpi engraving pattern was engraved using the following laser.
(3-1) Laser (i) (Stork AGRIOS 5212M (made by Stork, Austria, equipped with a gas flow type laser transmitter with a maximum output of 500 W))
When performing laser engraving using this laser, the following conditions were followed.
Speed (engraving speed) (m / sec): change as appropriate Power limit (percentage of maximum output) (%): change as appropriate Screen frequency (lpi): change as appropriate (3-2) Laser (ii) (UK, ZED) Manufactured, trademark "ZED-mini-1000" (manufactured by Coherent, USA, equipped with a maximum output 250W carbon dioxide laser)
When performing laser engraving using this laser, the following conditions were followed.
Bottom Power (percentage of maximum output) (%): Change as appropriate Width: 0.5 mm
Speed (engraving speed) (m / sec): Change as appropriate

(4) Evaluation of printing quality Printing was performed using a printing plate subjected to laser engraving, and the printing quality was evaluated.
The printer used was “FlexPress16S” (trademark, manufactured by Fischer & Krecke, Germany).
The ink was prepared using a solvent “XS-812” (trademark, manufactured by Dainippon Ink & Chemicals, Inc.), and the viscosity of the ink was 8.4 seconds using a Zahn cup No. 4 (diameter 4 mm opened in a 45 cc cup). The number of seconds required for the ink to fall to 30 cm below from the hole of the above was used.
A milk white polyethylene film having a thickness of 45 μm was used as the printing material.
The number of wires of the anilox roll was 900 (lpi), and the cell volume of the anilox roll was 4 cc.
The printing speed was 200 m / min.
The evaluation of the area ratio of the halftone dots of the printed material was performed using an image analysis apparatus (trademark “LUZEX” manufactured by NIRECO Co., Ltd.). The printed matter was photographed so that about 20 dots could be accommodated in one screen, and the photographed image was binarized by dividing it into ink adhering portions (dots) and non-adhering portions. Based on this binarized data, the area ratio with respect to the whole area where the ink was deposited was obtained and was defined as “dot area ratio”.

(5) Evaluation of printed matter The dot area ratio of the printed matter obtained in (4) was measured by the method described in (4) above, and the dot gain curve was plotted. The dot gain curve is a diagram in which the area ratio of halftone dots of the engraving original data is plotted on the x axis of the xy axis, and the area ratio of halftone dots of the printed material is plotted on the y axis. The presence or absence of density jumps was confirmed between 20% and 80% of the engraving source data. Density jump refers to a portion where there is an intermittent change in the dot gain curve, and if there is a density jump, the gradation of the halftone dot of the printed material becomes narrow and the high-definition print quality is impaired. Specifically, the engraving source data increases by 5%, while the halftone dot of the printed material increases by 15% or more.
Further, it was evaluated whether or not halftone dots were printed uniformly between 20% and 80% of the engraving original data and whether there was a moire-like geometric pattern. This geometric pattern has a great influence on multicolor printing and greatly deteriorates the printing quality.

Example 1
Laser (i) conditions were as follows: Speed: 8.0 m / sec, Power limit: 55%, Screen line number: 133 lpi, Data resolution: 2032 dpi, Engraving feed pitch: 12.5 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. The dot gain curve was plotted in FIG. 1, but no density jump was observed.
Moreover, when the halftone dots were visually evaluated, the halftone dots were uniform. In addition, the gradation pattern of the obtained printed matter had a smooth gradation, and the printed matter as designed was obtained for all of the fine lines, white lines, fine characters, and white fine characters.

(Example 2)
The conditions of laser (i) were as follows: Speed: 7.0 m / sec, Power limit: 40%, number of screen lines: 133 lpi, data resolution: 2032 dpi, engraving feed pitch: 12.5 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. The dot gain curve was plotted in FIG. 1, but no density jump was observed.
Moreover, when the halftone dots were visually evaluated, the halftone dots were uniform. In addition, the gradation pattern of the obtained printed matter had a smooth gradation, and the printed matter as designed was obtained for all of the fine lines, white lines, fine characters, and white fine characters.

(Example 3)
The conditions of laser (i) were as follows: Speed: 10.0 m / sec, Power limit: 55%, number of screen lines: 150 lpi, data resolution: 2540 dpi, and engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. The dot gain curve was plotted in FIG. 1, but no density jump was observed.
Moreover, when the halftone dots were visually evaluated, the halftone dots were uniform. In addition, the gradation pattern of the obtained printed matter had a smooth gradation, and the printed matter as designed was obtained for all of the fine lines, white lines, fine characters, and white fine characters.

Example 4
The conditions of laser (i) were as follows: Speed: 8.5 m / sec, Power limit: 40%, number of screen lines: 150 lpi, data resolution: 2540 dpi, engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. The dot gain curve was plotted in FIG. 1, but no density jump was observed.
Moreover, when the halftone dots were visually evaluated, the halftone dots were uniform. In addition, the gradation pattern of the obtained printed matter had a smooth gradation, and the printed matter as designed was obtained for all of the fine lines, white lines, fine characters, and white fine characters.

(Example 5)
The conditions of laser (ii) were as follows: Speed: 7.0 m / sec, Bottom Power: 70%, number of screen lines: 150 lpi, data resolution: 2540 dpi, engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-2) to obtain a printing plate.
Printing was performed using this printing plate, the obtained printed matter was evaluated, and the dot gain curve was plotted in FIG. 1, but no density jump was observed.
Moreover, when the halftone dots were visually evaluated, the halftone dots were uniform. In addition, the gradation pattern of the obtained printed matter had a smooth gradation, and the printed matter as designed was obtained for all of the fine lines, white lines, fine characters, and white fine characters.

(Comparative Example 1)
The conditions of laser (i) were as follows: Speed: 12.5 m / sec, Power limit: 100%, number of screen lines: 133 lpi, data resolution: 2032 dpi, engraving feed pitch: 12.5 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. When the dot gain curve was plotted in FIG. 2, a density jump was observed, and a discontinuous dot gain curve was obtained.
When the halftone dots were visually evaluated, the halftone dots were found to be non-uniform, and the gradation pattern of the obtained printed matter had some smooth gradation. In addition, as for the fine line, the white line, the fine character, and the white fine character, the printed matter as designed was obtained.

(Comparative Example 2)
The conditions of laser (i) were as follows: Speed: 3.0 m / sec, Power limit: 15%, number of screen lines: 133 lpi, data resolution: 2032 dpi, engraving feed pitch: 12.5 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. When the dot gain curve was plotted in FIG. 2, a density jump was observed, and a discontinuous dot gain curve was obtained.
When the halftone dots were visually evaluated, the halftone dots were found to be non-uniform, and the gradation pattern of the obtained printed matter had some smooth gradation. In addition, as for the fine line, the white line, the fine character, and the white fine character, the printed matter as designed was obtained.

(Comparative Example 3)
The conditions of laser (i) were as follows: Speed: 16.0 m / sec, Power limit: 100%, number of screen lines: 150 lpi, data resolution: 2540 dpi, engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the printed matter was evaluated. When the dot gain curve was plotted in FIG. 2, a density jump was observed, and a discontinuous dot gain curve was obtained.
When the halftone dots were visually evaluated, the halftone dots were found to be non-uniform, and the gradation pattern of the obtained printed matter had some smooth gradation. In addition, as for the fine line, the white line, the fine character, and the white fine character, the printed matter as designed was obtained.

(Comparative Example 4)
The conditions of laser (i) were as follows: Speed: 2.0 m / sec, Power limit: 15%, number of screen lines: 150 lpi, data resolution: 2540 dpi, and engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-1) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. When the dot gain curve was plotted in FIG. 2, a density jump was observed, and a discontinuous dot gain curve was obtained.
When the halftone dots were visually evaluated, the halftone dots were found to be non-uniform, and the gradation pattern of the obtained printed matter had some smooth gradation. In addition, as for the fine line, the white line, the fine character, and the white fine character, the printed matter as designed was obtained.

(Comparative Example 5)
The conditions of laser (ii) were as follows: Speed: 10.0 m / sec, Bottom Power: 100%, screen line number: 150 lpi, data resolution: 2540 dpi, engraving feed pitch: 10.0 μm. Other conditions were the same as those described in (3-2) to obtain a printing plate.
Printing was performed using this printing plate, and the obtained printed matter was evaluated. When the dot gain curve was plotted in FIG. 2, a density jump was observed, and a discontinuous dot gain curve was obtained.
When the halftone dots were visually evaluated, the halftone dots were found to be non-uniform, and the gradation pattern of the obtained printed matter had some smooth gradation. In addition, as for the fine line, the white line, the fine character, and the white fine character, the printed matter as designed was obtained.

Table 1 shows data of the dot area ratio of the engraving original data and the dot area ratio of the printed matter in Examples 1 to 5 and Comparative Examples 1 to 5.
Summarizing the above results, there is no density jump in the dot gain curve of the printed material using the printing plates of Examples 1 to 5 where laser engraving was performed at an output of 40% to 70% of the maximum output of the laser. High-definition print quality was achieved. In contrast, in Comparative Examples 1 to 5 in which laser engraving was performed at an output of 100% or 15% of the maximum output of the laser, a density jump was observed between 50% and 55% or between 55% and 60%. High definition print quality could not be realized.

  The present invention is suitable as a method for producing various printing plates such as flexographic printing, gravure printing, and dry offset printing. Also, surface pattern formation such as embossing, relief image formation for printing such as tiles, conductors for electronic components, semiconductors, insulators, pattern formation, antireflection films for optical components, color filters, (near) infrared cut filters, etc. Used for pattern formation of functional materials, and for coating film / pattern formation of alignment films, underlayers, light-emitting layers, electron transport layers, and encapsulant layers in the production of display elements such as liquid crystal displays or organic electroluminescence displays it can.

Claims (4)

  A method for producing a concavo-convex pattern including a laser engraving process for engraving a resin layer using a laser, wherein the laser engraving process has an output of 20% to 80% of a maximum output of a laser to be used, and is 50 W or more and 1000 W In the following, a method for producing a concavo-convex pattern, which is a step of engraving a resin layer with a line number of 120 lpi or more.   The manufacturing method of the uneven | corrugated pattern of Claim 1 whose engraving speed of the resin layer in the said laser engraving process is 2 m / s or more and 18 m / s or less.   The manufacturing method of the uneven | corrugated pattern of Claim 1 or 2 whose engraving feed pitch of the said laser is 5 micrometers or more and 20 micrometers or less.   The manufacturing method of the uneven | corrugated pattern as described in any one of Claim 1 to 4 whose uneven | corrugated pattern is a printing plate.