JP4375705B2 - Laser engraving printing master - Google Patents

Description

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【表２】

【００７８】
【発明の効果】
本発明により、版の内部まで十分な硬度を有し、かつ、直接レーザー彫刻してレリーフ画像を制作する際には、カスの発生を抑制し、そのカスを容易に除去できるばかりででなく、彫刻の形状が優れ、印刷面のタックが小さい印刷版を製作しうる近赤外線レーザー彫刻が可能な印刷原版を提供することができる。本発明は特に、通常の樹脂版では光吸収が少なく使用できない近赤外線領域のレーザー光を用いた彫刻に有用である。[0001]
[Technical field to which the present invention pertains]
The present invention relates to a laser engraving printing original plate suitable for forming a relief image for a flexographic printing plate by laser engraving, forming a pattern for surface processing such as embossing, and forming a relief image for printing such as a tile. It is related with the printing original plate suitable for the engraving using the laser which has.
[0002]
[Prior art]
Flexographic printing used for packaging materials such as cardboard, paper containers, paper bags, flexible packaging films, wallpaper materials, decorative materials such as decorative boards, and label printing has increased its specific gravity among various printing methods. For the production of the printing plate used for this, a photosensitive resin is usually used, and a liquid resin or a solid resin plate formed into a sheet shape is used, a photomask is placed on the photosensitive resin, and the mask is used. A method of irradiating light through the substrate to cause a crosslinking reaction and then washing off the non-crosslinked portion with a developer has been used. In recent years, a thin light-absorbing layer called a black layer has been provided on the surface of a photosensitive resin, and this is irradiated with laser light to form a mask image directly on the photosensitive resin plate, and then light is irradiated through the mask to cause a crosslinking reaction. Later, a technique called so-called flexo CTP was developed in which the non-crosslinked portion of the light non-irradiated portion was washed away with a developing solution, and its adoption has been promoted due to the effect of improving the efficiency of printing plate production. However, this technique also has a limited efficiency improvement effect such as the development process remaining, and development of a technique that directly forms a relief image on a printing original plate using a laser and does not require development is required. . In this case, the portion irradiated with the laser light is removed to form a recess.
[0003]
As the method, a method of engraving a printing original plate directly with a laser can be mentioned. Producing letterpress printing plates and stamps by this method has already been performed, and materials used therefor are also known.
Japanese Patent Laid-Open No. 2001-121833 (European Patent Publication No. 10808083) describes that silicone rubber is used and carbon black is mixed therein as a laser beam absorber. However, this is not a photosensitive resin. It is produced by a process of mixing a laser beam absorber before forming into a sheet. A printing original plate formed from a crosslinked rubber has problems such as a low engraving speed because it is difficult to melt or decompose by irradiation with a laser beam, and the engraving residue is burned and difficult to remove.
[0004]
On the other hand, in Japanese Patent Nos. 2846954 and 2846955 (US Patent Nos. 5798202 and 5804353), thermoplastic elastomers such as SBS, SIS and SEBS are mechanically, photochemically and thermochemically reinforced. The use of different materials is disclosed. When a thermoplastic elastomer is used, engraving with a laser having an oscillation wavelength in the near-infrared or infrared region melts even the resin that greatly deviates from the laser beam diameter due to heat, resulting in high resolution. The sculpture pattern cannot be formed. Therefore, it is essential to reinforce mechanically by adding a filler to the thermoplastic elastomer layer. In the above patent, carbon black having a particularly high mechanical reinforcing effect is mixed in a large amount for the purpose of mechanical reinforcement of the thermoplastic elastomer layer and improvement of laser light absorption.
[0005]
When engraving a printing original plate using a laser beam having an oscillation wavelength in the near infrared region, since most resins do not have light absorption in this wavelength region, a substance that absorbs laser light is contained in the printing original plate. It is essential. In general, a method of mixing black carbon black, a pigment or the like in a resin and then forming the sheet into a sheet is taken. However, in this method, since carbon black or pigment has light absorption in the ultraviolet or visible light region, the photosensitive resin composition is photocured using light in the ultraviolet region or visible light region to ensure mechanical strength. However, there was a problem that the inside of the plate was insufficiently cured. In other words, when laser-engraved printing masters that are not sufficiently photocured, a large amount of waste (including liquid viscous materials) is generated, which not only takes a lot of time to process, but also provides relief. The edge part rises due to melting, or solid debris is fused at the edge part, or the halftone dot shape collapses. In particular, when carbon black is contained in a large amount, there is a problem that engraving exceeds the design dimension. There is also a problem that carbon black, which is generally regarded as harmful, is released in large quantities into the atmosphere.
[0006]
In addition, if a large amount of viscous liquid residue, which is estimated to be a decomposition product of resin, is generated during laser engraving, it not only contaminates the optical system of the laser device, but also on the surface of optical components such as lenses and mirrors. The adhering liquid resin causes seizure, which is a major cause of trouble on the apparatus.
There are very few dyes that absorb light in the near-infrared region and little light absorption in the ultraviolet region. If such a dye is used, the photosensitive resin composition is formed before forming into a sheet or cylindrical printing original plate. Although it is possible to adopt a method of mixing dyes, it is extremely difficult to obtain such dyes.
[0007]
In JP-A-57-189439, there is a description of a light-shielding screen for antireflection in which a photosensitive resin composition containing silica particles is patterned using photolithography and the formed pattern is dyed with a pigment. There is no mention of laser engraving or porous particles. This anti-reflection light shielding screen is mounted on the surface of a display tube of a television receiver, and is used for the purpose of shielding external light incident on the image surface. In this patent document, dyeing is performed for the purpose of improving the light-shielding property of the obtained pattern, and it is used when forming a pattern by improving the absorbability of laser light used for laser engraving. The object of the present invention is completely different from the object of the present invention.
[0008]
[Patent Document 1]
JP 2001-121833 A [Patent Document 2]
Japanese Patent No. 2846954 [Patent Document 3]
Japanese Patent No. 2846955 [Patent Document 4]
JP-A-57-189439 [0009]
[Problems to be solved by the invention]
The present invention has sufficient hardness up to the inside of the plate, and when producing a relief image by direct laser engraving, not only can the debris be suppressed and the debris can be easily removed, but also the shape of the engraving An object of the present invention is to provide a printing original plate capable of producing a printing plate having excellent printing surface and small tack on the printing surface. In particular, an object is to provide a printing original plate capable of near-infrared laser engraving.
[0010]
[Means for Solving the Problems]
The present inventors have intensively studied and printed a sheet-like or cylindrical resin plate formed by photocuring a photosensitive resin composition by dyeing it with a dye having light absorption characteristics in the wavelength region of laser light used for engraving. The inventors have found that the presence of the dye up to the inside of the original plate can be engraved with laser light, and have completed the present invention. When forming a laser engraving printing original plate by photocrosslinking and curing a photosensitive resin composition, it is common to mix a dye or pigment having light absorption in the wavelength region of laser light used for engraving into the photosensitive resin composition. However, since most dyes and pigments have light absorption characteristics even at the wavelength of light used for photocrosslinking curing, there is a problem that the light does not penetrate into the resin layer and the curability inside the resin layer is insufficient. there were. In the printing original plate formed in the present invention, in the step of photocrosslinking and curing the photosensitive resin composition to form into a sheet or cylinder, the dye is not present in the resin plate. It is completely different from the conventional methods for producing laser engraving printing original plates, which can be sufficiently cured to the inside of the plate and can be laser engraved by dyeing with a dye having light absorption in the wavelength region of the laser beam used for engraving thereafter. I found an epoch-making method.
[0011]
The present invention is as follows.
1. A printing original plate comprising a cured layer of a sheet-shaped or cylindrical laser-engravable photosensitive resin composition, the cured layer having an inorganic porous body (c) and irradiated with laser light Laser engraving printing original plate characterized in that it has a layer dyed with a dye having light absorption at the wavelength of the laser beam in the depth direction from the surface on the side of the surface, and the thickness of the dyed layer is 0.01 mm or more .
2. 1. The dye has light absorption in the near infrared region of 700 nm to 2 μm. The laser engraving printing original plate described in 1.
3. 1. The dye has a reactive functional group Or 2. The laser engraving printing original plate described in 1.
4). 1. The dye density distribution in the dyed layer is characterized in that the density decreases in the depth direction from the surface of the printing original plate. To 3. The laser engraving printing original plate as described in any of the above.
[0012]
5. 1. A light transmittance measured by transmitting light from a direction perpendicular to a printing original plate dyed with a dye is 10% or less at a wavelength of a laser beam used for laser engraving. To 4. The laser engraving printing original plate as described in any of the above.
6). The photosensitive resin composition is a resin (a) having a number average molecular weight of 1000 to 200,000, an organic compound (b) having a polymerizable unsaturated group having a number average molecular weight of less than 1000, a specific surface area of 10 m ² / g or more and 1500 m ² / g. And an inorganic porous body (c) having an average pore diameter of 1 nm to 1000 nm, a pore volume of 0.1 ml / g to 10 ml / g, and an oil absorption of 10 ml / 100 g to 2000 ml / 100 g. Characterized by The laser engraving printing original plate described in 1.
7). 5. 20 wt% or more of the total amount of the organic compound (b) is at least one alicyclic or aromatic derivative. The laser engraving printing original plate described in 1.
8). The inorganic porous material (c) is a spherical particle having a number average particle diameter of 0.1 μm or more and 100 μm or less, and at least 70% of spherical particles having a sphericity of 0.5 to 1. 6 . The laser engraving printing original plate described in 1.
[0013]
9. (I) a step of laminating a photosensitive resin composition layer on a sheet-like or cylindrical support, (ii) a step of irradiating and curing light on the entire surface of the formed photosensitive resin composition layer, (iii) obtained A method for producing a laser engraving printing original plate, comprising a step of dyeing the laminate into the resin plate by dyeing the laminate.
10. 1. A multilayer laser engraving printing original plate having at least one elastomer layer having a Shore A hardness of 20 or more and 70 or less at a lower part of the printing original plate described in 1).
11. 9. The elastomer layer is formed by curing the photosensitive resin composition. The multilayer laser engraving printing original plate described in 1.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, it demonstrates in detail focusing on the preferable embodiment of this invention.
The printing original plate of the present invention is a sheet-shaped or cylindrical printing original plate that can be engraved using laser light. The portion irradiated with the laser light is removed, and a recess is formed. In the depth direction from the surface irradiated with laser light, having a dyed layer dyed with a dye having light absorption at the wavelength of the laser light used for engraving, the thickness of the dyed layer is 0.01 mm or more, Preferably it is 0.05 mm or more. The entire printing original plate may be dyed in the thickness direction. In particular, it is effective when engraving using laser light having an oscillation wavelength in the near-infrared region where light absorption of many resins forming the resin plate is small, that is, in the region of wavelength from 700 nm to 2 μm. For example, as a laser having an oscillation wavelength in the near infrared region with a wavelength of 700 nm to 2 μm, a semiconductor laser, a YAG laser, a fiber laser, a surface emitting laser, and the like can be given. Laser light in the near-infrared region is extremely important as a tool for producing a high-definition printing plate because the beam can be narrowed down to about twice the wavelength. If the thickness of the dyed layer is 0.01 mm or more, the ink can be sufficiently received as a printing plate. In the present invention, the plate before dyeing is defined as a resin plate, the plate after dyeing is defined as a printing original plate, and the plate after laser engraving is defined as a printing plate.
[0015]
The dye used for dyeing is not particularly limited as long as it has light absorption at the oscillation wavelength of the laser light used for engraving. When used in the color printing field, depending on the color of the ink used, it is preferable that it can be fixed in the printing original plate so that the coloring matter does not elute into the ink. For this reason, after dyeing with a dye, it is preferable to perform a treatment for fixing the dye in the resin, or to use a dye having a functional group that forms a bond with the resin constituting the resin plate in the dye molecule. The bond with the resin includes a covalent bond, an ionic bond, a hydrogen bond, etc., and a dye that forms a covalent bond is particularly preferred because of the strength of the bond. In order to form a covalent bond, it is desirable to use a dye having a reactive functional group in the dye molecular structure. When classified by reaction mechanism, reactive dyes such as nucleophilic substitution reaction type, conjugate addition reaction type, addition / elimination type, and acidic condition reaction type can be exemplified. These dyes react with functional groups such as hydroxyl groups, amino groups, amide groups, SH groups, and carboxyl groups in the resin, and are fixed in the resin. Specific examples of reactive functional groups include chlorotriazine, dichlorotriazine, trichloropyrimidine, sulfatoethylsulfone, dichloroquinoxaline, α-bromoacrylamide, methylsulfonylchloromethylpyrimidine, chloro-difluoropyrimidine, phenylphosphonic acid, fluoro A triazine etc. can be mentioned. The greater the number of nitrogen and chlorine in the heterocyclic structure of the reactive functional group, the higher the reactivity and the lower the reaction temperature.
[0016]
A scale indicating the light absorption characteristics of the dye at the wavelength of the laser light to be used is defined as follows. A dye solution having a concentration of 10 mg / liter is prepared, and the absorbance when 1 cm of light having the above wavelength passes through the solution is 0.01 or more, preferably 0.1 or more. In order to dye after forming a resin plate in a sheet form or a cylindrical form, it is preferable that the dye used is soluble in a solvent. A preferred method is a method of immersing a resin plate in a dye solution. Examples of the solvent include organic solvents such as water, alcohols, esters, ethers, and aromatics that do not significantly reduce the mechanical properties of the printing original plate. The solvent may be a single substance or a mixture. The dyeing speed can be increased by using a resin plate that swells to some extent. The solubility of the dye is preferably 0.1 g / liter or more, more preferably 0.5 g / liter or more, and still more preferably 1 g / liter or more. During dyeing, the dye-containing treatment solution may be heated. Further, a penetrant such as an anionic or nonionic surfactant can be added as a dyeing assistant.
[0017]
As another method for dyeing, a method in which a dye is attached to the surface of the printing original plate by a method such as vapor deposition or spray coating, and then diffused in the printing original plate by heat treatment can be employed. In particular, if a vapor deposition method is used, it is not necessary to dissolve the dye in a solvent, and it is possible to use a dye having extremely low solubility.
The simplest method for measuring the thickness of the dyed layer is to cut the dyed printing original plate vertically and observe the cross section with a microscope from the vertical direction. In that case, the thickness of a portion having a color tone different from the color tone of the resin plate before dyeing is obtained. The entire printing original plate may be dyed in the thickness direction. In that case, it can confirm by observing the cross section of the resin plate before dyeing | staining similarly in a microscope. Therefore, it is desirable to use a CCD camera for cross-sectional observation or to evaluate by taking a photograph.
[0018]
In addition, the method for measuring the concentration distribution of the dye in the dyed layer is prepared by adjusting the section of the cross section, such as light absorption measurement by microscope FT-IR, microscope spectrophotometer, electron probe microanalysis, Auger electron spectroscopy, etc. A method capable of quantitative analysis of a minute region is preferable. It is necessary to select an evaluation method according to the dye used for dyeing. That is, it is preferable to analyze by paying attention to infrared absorption specific to the dye used for dyeing, elements constituting the molecule, or impurities in the dye. As a method for producing a thin-film sample piece, it is preferable to use an apparatus such as a microtome with a cooling device.
[0019]
In the cross section of the printing original plate, the concentration distribution of the dye in the dyed layer is a concentration distribution that is high in the vicinity of the surface because the dye diffuses from the surface of the resin plate, and decreases toward the inside. Therefore, when engraving using laser light, the engraving speed near the surface of the printing original plate is high, and the dye density decreases as it goes inside, so the engraving speed becomes slow, and if the dye density falls below a certain threshold, engraving becomes impossible. Therefore, excessive engraving can be prevented by controlling the thickness of the dyed layer. In particular, when producing a flexographic printing plate, it is necessary to engrave relatively deeply, and it is usual to enlarge the skirt portion of the pattern. For example, in the case of a halftone dot pattern, the pattern shape is conical. In the dye distribution of the dyed layer, if the density distribution is such that the dye density decreases in the depth direction of the printing original plate, there is an effect that the skirt portion of the pattern can be easily formed.
[0020]
The light transmittance measured by transmitting light from the perpendicular direction to the printing original plate dyed with the dye is preferably 10% or less, more preferably 5% or less, and further preferably 1% or less at the wavelength of the laser beam used for engraving. It is. If the light transmittance is 10% or less, the resin can be melted or decomposed and engraved by absorbing laser light.
[0021]
The resin composition constituting the resin plate is not limited to the photosensitive resin composition, and may be a non-photosensitive resin composition, for example, a thermoset elastomer, but can be dyed. In order to ensure the engraving speed at the time of laser engraving, a material that is easily melted or decomposed is preferred, and thus a photo-crosslinked photopolymer resin composition is desirable. Examples of the method of photocrosslinking the photosensitive resin composition include a method of irradiating ultraviolet rays or visible rays in the range of 200 nm to 600 nm, or a method of irradiating an electron beam. From the viewpoint of workability, it is more preferable to use light in the ultraviolet region of 200 nm to 450 nm. By using light in the range of 200 nm to 600 nm, the resin can be sufficiently crosslinked without being decomposed, and a commercially available photopolymerization initiator can be used.
[0022]
The number average molecular weight of the resin (a) is preferably in the range of 1000 to 200,000. A more preferable range is 5000 to 100,000. When the number average molecular weight is in the range of 1,000 to 200,000, the mechanical strength of the printing original plate can be secured, and the resin can be sufficiently melted or decomposed during laser engraving. The number average molecular weight of the present invention is measured using gel permeation chromatography (GPC) and evaluated with respect to a polystyrene sample having a known molecular weight.
[0023]
The feature of the present invention is to absorb and remove liquid debris generated in the laser engraving process by including the inorganic porous material (c) in the photosensitive resin cured product layer capable of laser engraving. The photosensitive resin composition before photocuring is composed of a resin (a) having a number average molecular weight of 1,000 or more and 200,000 or less, an organic compound (b) having a number average molecular weight of less than 1,000 and having a polymerizable unsaturated group in the molecule, and inorganic It is preferable to contain a porous body (c).
[0024]
The type of the resin (a) may be an elastomer or a non-elastomer, and may be a solid polymer or a liquid polymer at 20 ° C. Moreover, when using a thermoplastic resin, 30 wt% or more of a polymer total weight is preferable, More preferably, it is 50 wt% or more, More preferably, it is 70 wt% or more. If the content of the thermoplastic resin is 30 wt% or more, the resin is sufficiently fluidized by laser beam irradiation and is absorbed by the inorganic porous body described later. However, when a resin having a softening temperature exceeding 300 ° C. is used, the temperature at which the resin is molded into a cylindrical shape is naturally high, and there is a concern that other organic substances may be denatured and decomposed by heat. It is preferable to apply in a dissolved state.
[0025]
In particular, it is preferable to use a liquid polymer at 20 ° C. as the resin (a) from the viewpoint of ease of processing into a cylindrical resin plate and ease of decomposition with respect to heat. When a liquid polymer is used as the resin (a) at 20 ° C., the formed photosensitive resin composition is also liquid, and can be molded at a low temperature.
The number average molecular weight of the resin (a) used in the present invention is preferably in the range of 1000 to 200,000. A more preferable range is 5000 to 100,000. When the number average molecular weight is in the range of 1,000 to 200,000, the mechanical strength of the printing original plate can be secured, and the resin can be sufficiently melted or decomposed during laser engraving. The number average molecular weight of the present invention is measured using gel permeation chromatography (GPC) and evaluated against a polystyrene preparation with a known molecular weight.
[0026]
As a technical feature of the present invention, it is possible to absorb and remove liquefied debris by irradiation with a laser beam using an inorganic porous material. As the cured photosensitive resin to be used, a resin that is easily liquefied or a resin that is easily decomposed is preferable. Examples of resins that are easily decomposed include styrene, α-methylstyrene, α-methoxystyrene, acrylic esters, methacrylic esters, ester compounds, ether compounds, nitro compounds, carbonates as monomer units that are easily decomposed in the molecular chain. Preferably, compounds, carbamoyl compounds, hemiacetal ester compounds, oxyethylene compounds, aliphatic cyclic compounds, and the like are included. Especially polyethers such as polyethylene glycol, polypropylene glycol, polytetraethylene glycol, aliphatic polycarbonates, aliphatic carbamates, polymethyl methacrylate, polystyrene, nitrocellulose, polyoxyethylene, polynorbornene, polycyclohexadiene hydrogenated product Alternatively, a polymer having a molecular structure such as a dendrimer having many branched structures is a representative example of those that are easily decomposed.
[0027]
A polymer containing a large number of oxygen atoms in the molecular chain is preferred from the viewpoint of degradability. Among these, a compound having a carbonate group, a carbamate group, and a methacryl group in the polymer main chain is preferable because of its high thermal decomposability. For example, polyesters and polyurethanes synthesized from (poly) carbonate diol or (poly) carbonate dicarboxylic acid as raw materials, polyamides synthesized from (poly) carbonate diamine as raw materials, and the like can be cited as examples of polymers having good thermal decomposability. . These polymer main chains and side chains may contain a polymerizable unsaturated group. In particular, when a reactive functional group such as a hydroxyl group, an amino group or a carboxyl group is present at the terminal, it is easy to introduce a polymerizable unsaturated group at the terminal of the main chain.
[0028]
Although it does not specifically limit as a thermoplastic elastomer used by this invention, SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-) which are styrenic thermoplastic elastomers. Polystyrene), olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, amide-based thermoplastic elastomers, silicone-based thermoplastic elastomers, and the like. In order to further improve the thermal decomposability, it is also possible to use a polymer in which an easily decomposable functional group such as a carbamoyl group or a carbonate group having a high decomposability is introduced into the main chain in the molecular skeleton. Further, it may be used by mixing with a polymer having higher thermal decomposability. Since the thermoplastic elastomer is fluidized by heating, it can be mixed with the inorganic porous material used in the present invention. 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.
[0029]
Depending on the application of the printing plate, the type of thermoplastic elastomer can be selected. 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. For normal printing plate applications, a relatively hard material is required for embossing applications that form surface irregularities of paper, film, and building materials in areas where the Shore A hardness is 20 to 75 degrees, and Shore D The hardness is in the range of 30 to 80 degrees.
[0030]
The thermoplastic resin is not particularly limited as a non-elastomeric one, but is not limited to polyester resin, unsaturated polyester resin, polyamide resin, polyamideimide resin, polyurethane resin, unsaturated polyurethane resin, polysulfone resin, polyethersulfone resin, Polyimide resin, polycarbonate resin, wholly aromatic polyester resin and the like can be mentioned.
[0031]
The softening temperature of the thermoplastic resin of the present invention is preferably 50 ° C. or higher and 300 ° C. or lower. A more preferable range is 80 ° C. or higher and 250 ° C. or lower, and further preferably 100 ° C. or higher and 200 ° 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 300 ° C. or lower, it is not necessary to heat to a very high temperature when processing into a cylindrical shape, and it is not necessary to alter or decompose other compounds to be mixed. The measurement of the softening temperature of the present invention is defined by the first temperature at which the viscosity changes greatly (the slope of the viscosity curve changes) when the temperature is increased from room temperature using a dynamic viscoelasticity measuring device. To do.
[0032]
The resin (a) of the present invention may be a solvent-soluble resin. Specific examples include polysulfone resins, polyether sulfone resins, epoxy resins, alkyd resins, polyolefin resins, polyester resins, and the like.
The resin (a) of the present invention usually does not have a highly reactive polymerizable unsaturated group, but may have a highly reactive polymerizable unsaturated group at the end or side chain of the molecular chain. I do not care. When a polymer having a highly reactive polymerizable unsaturated group is used, a printing original plate having extremely high mechanical strength can be produced. Particularly in polyurethane-based and polyester-based thermoplastic elastomers, it is possible to introduce a highly reactive polymerizable unsaturated group into the molecule relatively easily. The term “intramolecular” as used herein includes the case where a polymerizable unsaturated group is directly attached to the terminal of the polymer main chain, the terminal of the polymer side chain, the polymer main chain, or the side chain. For example, it is possible to directly use a polymerizable unsaturated group introduced at the molecular end. Alternatively, a hydroxyl group, amino group, epoxy group, carboxyl group, acid anhydride group, ketone group, hydrazine residue can be used. A binder having a plurality of groups capable of binding to a reactive group having a molecular weight of about several thousand having a plurality of reactive groups such as an isocyanate group, an isothiocyanate group, a cyclic carbonate group, and an ester group (for example, a hydroxyl group or an amino group) Polyisocyanate, etc.) in the case of (2), reacting with an organic compound having a polymerizable unsaturated group and a group that reacts with the terminal binding group after the molecular weight is adjusted and converted to the terminal binding group. And a method such as a method of introducing a polymerizable unsaturated group at the terminal. The organic compound (b) of the present invention is a compound having an unsaturated bond involved in a radical or addition polymerization reaction, and the number average molecular weight is 5000 or less in consideration of easiness of dilution with the resin (a). preferable. Examples of the organic compound (b) 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 Derivatives thereof, allyl compounds such as allyl alcohol and allyl isocyanate, unsaturated dicarboxylic acids such as maleic anhydride, maleic acid and fumaric acid and derivatives thereof, vinyl acetates, N-vinylpyrrolidone, N-vinylcarbazole, cyanate esters, etc. However, (meth) acrylic acid and its derivatives are preferred examples from the viewpoints of the abundance of their types and price.
[0033]
The derivatives include alicyclics such as cycloalkyl-, bicycloalkyl-, cycloalkene-, bicycloalkene-, aromatics such as benzyl-, phenyl-, phenoxy-, alkyl-, halogenated alkyl-, alkoxyalkyl-, Esters of polyhydric alcohols such as hydroxyalkyl-, aminoalkyl-, tetrahydrofurfuryl-, allyl-, glycidyl-, alkylene glycol-, polyoxyalkylene glycol-, (alkyl / allyloxy) polyalkylene glycol- and trimethylolpropane Is given.
[0034]
In the present invention, the organic compound (b) having a polymerizable unsaturated bond can be selected from one or more types depending on the purpose. For example, when used as a printing plate, it has at least one long-chain aliphatic, alicyclic or aromatic derivative as an organic compound used to suppress swelling with respect to an organic solvent such as alcohol or ester which is a solvent for printing ink. Is preferred.
In order to increase the mechanical strength of the printing original plate obtained from the resin composition of the present invention, the organic compound (b) preferably has at least one alicyclic or aromatic derivative. In this case, the organic compound It is preferable that it is 20 wt% or more of the whole quantity of (b), More preferably, it is 50 wt% or more.
[0035]
In order to increase the rebound resilience of the printing plate, for example, a methacrylic monomer as described in JP-A-7-239548 can be used, or it can be selected using the technical knowledge of known photosensitive resins for printing.
The inorganic porous material (c) of the present invention is an inorganic particle having fine pores or fine voids in the particle, and absorbs and removes viscous liquid residue generated in a large amount in laser engraving. And also has an anti-tacking effect on the plate surface. The inorganic porous material of the present invention is added for the purpose of removing viscous liquid residue, and the number average particle diameter, specific surface area, average pore diameter, pore volume, and loss on ignition greatly affect its performance. To do.
[0036]
The present invention preferably employs a resin that can be easily cut by laser irradiation. In this case, a large amount of low molecular weight monomers and oligomers are generated at the time of molecular cutting. The biggest feature is that it introduces a new concept that has never been found in the conventional technical idea. Therefore, as described above, physical properties such as the number average particle diameter, specific surface area, average pore diameter, pore volume, loss on ignition, and oil supply amount of the porous inorganic absorbent containing porous silica used for the removal of viscous liquid waste are used. It becomes an important factor.
[0037]
The inorganic porous body (c) of the present invention preferably has a number average particle diameter of 0.1 to 100 μm. When a material having a particle size smaller than the number average particle size is used, dust engraves when engraving an original plate obtained from the resin composition of the present invention with a laser, contaminating the engraving apparatus, and the resin (a) and organic compound When mixing with (b), inconveniences such as an increase in viscosity, entrainment of bubbles, and generation of a large amount of dust occur. On the other hand, when a material larger than the above-mentioned number average particle size is used, a defect is generated in the relief image when laser engraving is performed, and the fineness of the printed matter is impaired. A more preferable range of the average particle diameter is 0.5 to 20 μm, and a further preferable range is 3 to 10 μm. The average particle size of the porous inorganic absorbent of the present invention is preferably measured using a laser scattering type particle size distribution measuring device.
[0038]
The range of the specific surface area of the inorganic porous material (c) of the present invention is 10 m ² / g or more and 1500 m ² / g or less. A more preferable range is 100 m ² / g or more and 800 m ² / g or less. When the specific surface area is 10 m ² / g or more, the removal of liquid residue during laser engraving is sufficient, and when the specific surface area is 1500 m ² / g or less, an increase in the viscosity of the photosensitive resin composition is suppressed, and thixotropic properties are obtained. Can be suppressed. The specific surface area of this invention is calculated | required based on a BET type | formula from the adsorption isotherm of nitrogen in -196 degreeC.
[0039]
The average pore diameter of the inorganic porous material (c) of the present invention greatly affects the absorption amount of liquid residue generated during laser engraving. A preferable range of the average pore diameter is 1 nm to 1000 nm, more preferably 2 nm to 200 nm, and still more preferably 2 nm to 50 nm. If the average pore diameter is 1 nm or more, the absorbability of liquid debris generated during laser engraving can be ensured, and if it is 1000 nm or less, the specific surface area of the particles is large and the amount of liquid debris absorbed can be sufficiently ensured. When the average pore size is less than 1 nm, the reason why the amount of absorbed liquid debris is small is not clear, but because liquid debris is viscous, it is estimated that it is difficult to enter the micropores and the amount of absorption is small. is doing. The average pore diameter of the present invention is a value measured using a nitrogen adsorption method. Those having an average pore diameter of 2 to 50 nm are particularly called mesopores, and the ability of porous particles having mesopores to absorb liquid waste is extremely high. The pore size distribution of the present invention is determined from the nitrogen adsorption isotherm at -196 ° C.
[0040]
The pore volume of the inorganic porous material (c) of the present invention is preferably from 0.1 ml / g to 10 ml / g, more preferably from 0.2 ml / g to 5 ml / g. When the pore volume is 0.1 m / g or more, the absorption amount of the viscous liquid residue is sufficient, and when it is 10 ml / g or less, the mechanical strength of the particles can be ensured. In the present invention, a nitrogen adsorption method is used to measure the pore volume. The pore volume of the present invention is determined from an adsorption isotherm of nitrogen at −196 ° C.
[0041]
A new concept of porosity is introduced to evaluate the properties of porous bodies. The porosity is the ratio of the specific surface area P to the surface area S per unit weight calculated from the average particle diameter D (unit: μm) and the density d (unit: g / cm ³ ) of the substance constituting the particles, It is defined by P / S. Since the surface area per particle is πD ² × 10 ⁻¹² (unit: m ² ) and the weight of one particle is (πD ³ d / 6) × 10 ⁻¹² (unit: g), the unit The surface area S per weight is S = 6 / (Dd) (unit: m ² / g). As the specific surface area P, a value measured by adsorbing nitrogen molecules on the surface is used.
[0042]
The porosity of the inorganic porous body (f) is preferably 20 or more, more preferably 50 or more, and still more preferably 100 or more. If the porosity is 20 or more, it is effective for removing adsorbed liquid residue. Since the specific surface area P increases as the particle diameter decreases, the specific surface area alone is not suitable as an index indicating the characteristics of the porous body. Therefore, considering the particle size, porosity was taken as a dimensionless index. For example, carbon black widely used as a reinforcing material such as rubber has a very large specific surface area of 150 m ² / g to 20 m ² / g, but the average particle size is extremely small, usually 10 nm to 100 nm. Therefore, when the porosity is calculated by setting the density to 2.25 g / cm ³ of graphite, it becomes a value in the range of 0.8 to 1.0, and is estimated to be a nonporous body having no porous structure inside the particle. The Since carbon black is generally known to have a graphite structure, the value of graphite was used for the density. On the other hand, the porosity of the porous silica used in the present invention is a high value well over 500.
[0043]
The inorganic porous material of the present invention preferably has a specific specific surface area and an oil absorption amount in order to obtain better adsorbability. This is defined by the amount of oil absorbed by 100 g of the inorganic porous body.
The preferred range of the oil absorption of the inorganic porous material (c) used in the present invention is 10 ml / 100 g or more and 2000 ml / 100 g or less, more preferably 50 ml / 100 g or more and 1000 ml / 100 g or less. If the oil absorption is 10 ml / 100 g or more, removal of the liquid residue generated during laser engraving is sufficient, and if it is 2000 ml / 100 g or less, the mechanical strength of the inorganic porous body can be sufficiently secured. The oil absorption was measured according to JIS-K5101.
The inorganic porous material (c) of the present invention is required to maintain the porous property without being deformed or melted by laser light irradiation in the infrared wavelength region. The loss on ignition when treated at 950 ° C. for 2 hours is preferably 15 wt% or less, more preferably 10 wt% or less.
[0044]
The particle shape of the inorganic porous material of the present invention is not particularly limited, and spherical, flat, needle-like, amorphous, or particles having protrusions on the surface can be used. Among these, spherical particles are particularly preferable from the viewpoint of wear resistance of the printing plate. It is also possible to use particles having hollow inside particles, spherical granules having a uniform pore diameter such as silica sponge, and the like. Although not particularly limited, for example, porous silica, mesoporous silica, silica-zirconia porous gel, porous alumina, porous glass and the like can be mentioned. Moreover, since the pore diameter cannot be defined for a layer having a gap of several to 100 nm such as a layered clay compound, in the present invention, the gap between the layers is defined as the pore diameter.
[0045]
Moreover, the surface of the inorganic porous body can be coated with a silane coupling agent, a titanium coupling agent, or other organic compounds, and subjected to a surface modification treatment to make particles more hydrophilic or hydrophobic.
In the present invention, these inorganic porous bodies (c) can be selected from one or more kinds, and by adding the inorganic porous body (c), generation of liquid debris during laser engraving and relief Improvements such as tack prevention of the printing plate are effectively performed.
[0046]
Sphericality is defined as an index that defines spherical particles. The sphericity used in the present invention is the ratio (D ₁ / D) of the maximum value D ₁ of the circle that completely enters the projected figure when the particle is projected to the minimum value D ₂ of the circle that completely enters the projected figure. ₂ ) Define. In the case of a true sphere, the sphericity is 1.0. The sphericity of the preferable spherical particles used in the present invention is preferably 0.5 or more and 1.0 or less, more preferably 0.7 or more and 1.0 or less. If it is 0.5 or more, the wear resistance as a printing plate is good. The sphericity of 1.0 is an upper limit value of sphericity. As the spherical particles, it is desirable that 70% or more, more preferably 90% or more of the particles have a sphericity of 0.5 or more. As a method of measuring the sphericity, a method of measuring based on a photograph taken using a scanning electron microscope can be used. At that time, it is preferable to take a picture at a magnification at which at least 100 particles enter the monitor screen. The D ₁ and D ₂ are measured on the basis of a photograph, but it is preferable to process the photograph using a digitizing device such as a scanner and then process the data using image analysis software.
[0047]
The ratio of the resin (a), the organic compound (b), and the inorganic porous body (c) in the photosensitive resin composition of the present invention is usually the organic compound (b) with respect to 100 parts by weight of the resin (a). Is preferably 5 to 200 parts by weight, and more preferably 20 to 100 parts by weight. The inorganic porous body (c) is preferably 1 to 100 parts by weight, and more preferably 2 to 50 parts by weight. A more preferable range is 2 to 20 parts by weight.
If the ratio of the organic compound (b) is in the above range, it is easy to balance the hardness and tensile strength / elongation of the obtained printing plate, the shrinkage at the time of crosslinking and curing is small, and the thickness accuracy can be ensured. it can.
[0048]
Further, if the amount of the inorganic porous material (c) is in the above range, the effect of preventing the tackiness of the plate surface and the effect of suppressing the generation of engraving liquid debris when laser engraving is sufficiently exhibited, and the printing plate The mechanical strength of can be secured. Further, the transparency can be maintained, and the hardness can be set to an appropriate range particularly when used as a flexographic plate. When a photosensitive resin composition is cured using light, particularly ultraviolet rays, to prepare a laser engraving printing original plate, light transmittance affects the crosslinking reaction. Therefore, it is effective to use a material having a refractive index close to that of the photosensitive resin composition.
[0049]
As a method of mixing the inorganic porous material in the photosensitive resin composition, a method of directly adding the inorganic porous material (c) in a state where the thermoplastic resin is heated and fluidized, or photopolymerization with the thermoplastic resin. Any method may be used in which the inorganic porous material (c) is added to the kneaded organic organic compound (b) first. However, it is preferable to avoid a method of mixing the inorganic porous material (c) directly with the photopolymerizable organic material (b) having a low molecular weight. That is, when this third method is used, the residue absorption performance of the inorganic porous material may be lowered. Although the reason for this is not clear, the polymerizable organic substance (b) in the pores in the exposure step when a low-viscosity organic compound penetrates into the pores or voids in the inorganic porous particles and a printing original plate is produced. Is presumed to harden and fill pores or voids.
[0050]
The photosensitive resin composition of the present invention is crosslinked by irradiation with light or electron beam to develop physical properties as a printing plate, and a polymerization initiator can be added at that time. Polymerization initiators can be selected from commonly used ones. For example, “Polymer Data Handbook-Fundamentals” edited by the Society of Polymer Sciences, published in 1986 by Baifukan, includes initiators for radical polymerization, cationic polymerization, and anionic polymerization. Yes. In addition, crosslinking by photopolymerization using a photopolymerization initiator is useful as a method for producing a printing original plate with good productivity while maintaining the storage stability of the resin composition of the present invention, and is used in that case. Known initiators can also be used, for example, benzoin alkyl ethers such as benzoin and benzoin ethyl ether, 2-hydroxy-2-methylpropiophenone, 4′-isopropyl-2-hydroxy-2-methylpropiophenone. Acetophenones such as 2,2-dimethoxy-2-phenylacetophenone and diethoxyacetophenone; 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1- ON, methyl phenylglyoxylate, benzophenone, benzyl, di In addition to photo radical polymerization initiators such as cetyl, diphenyl sulfide, eosin, thionine, and anthraquinones, photo cationic polymerization starts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts that absorb light and generate acids. And a polymerization initiator that absorbs light and generates a base. In general, the polymerization initiator is preferably used in an amount of 0.01 to 10 wt% of the total amount of the resin (a) and the organic compound (b).
In addition, a polymerization inhibitor, an ultraviolet absorber, a dye, a pigment, a lubricant, a surfactant, a plasticizer, a fragrance, and the like can be added to the resin composition of the present invention according to the purpose and purpose.
[0051]
As a method of molding the resin composition of the present invention into a sheet or cylinder, an existing resin molding method can be used. For example, a casting method, a method of extruding a resin from a nozzle or a die with a machine such as a pump or an extruder, adjusting the thickness with a blade, and adjusting the thickness by calendering with a roll can be exemplified. In that case, it is also possible to perform the molding while heating within a range that does not deteriorate the performance of the resin. Moreover, you may perform a rolling process, a grinding process, etc. as needed. Usually, it is often formed on an underlay called a back film made of a material such as PET or nickel, but it may be formed directly on a cylinder of a printing machine. The role of the back film is to ensure the dimensional stability of the printing original plate. Therefore, it is necessary to select one having high dimensional stability. When evaluated using the linear thermal expansion coefficient, the upper limit value of a preferable material is 100 ppm / ° C. or less, more preferably 70 ppm / ° C. or less. Specific examples of materials include polyester resin, polyimide resin, polyamide resin, polyamideimide resin, polyetherimide resin, polybismaleimide resin, polysulfone resin, polycarbonate resin, polyphenylene ether resin, polyphenylene thioether resin, polyethersulfone resin, all Examples thereof include liquid crystal resins composed of aromatic polyester resins, wholly aromatic polyamide resins, and epoxy resins. Further, these resins can be laminated and used. For example, a sheet or the like in which layers of polyethylene terephthalate having a thickness of 50 μm are laminated on both surfaces of a 4.5 μm thick wholly aromatic polyamide film may be used.
[0052]
Examples of a method for reducing the linear thermal expansion coefficient of the back film include a method of adding a filler, a method of impregnating or coating a resin on a mesh cloth such as wholly aromatic polyamide, or a glass cloth. As the filler, generally used organic fine particles, inorganic fine particles such as metal oxide or metal, organic / inorganic composite fine particles, and the like can be used. In addition, porous fine particles, fine particles having cavities inside, microcapsule particles, and layered compound particles in which a low molecular compound intercalates can be used. In particular, metal oxide fine particles such as alumina, silica, titanium oxide, and zeolite, latex fine particles made of polystyrene / polybutadiene copolymer, natural product-based organic fine particles such as highly crystalline cellulose, and the like are useful.
[0053]
By performing a physical and chemical treatment on the surface of the back film used in the present invention, the adhesiveness with the photosensitive resin composition layer or the adhesive layer can be improved. Examples of the physical treatment method include a sand blast method, a wet blast method for injecting a liquid containing fine particles, a corona discharge treatment method, a plasma treatment method, an ultraviolet ray or vacuum ultraviolet ray irradiation method, and the like. The chemical treatment method includes a strong acid / strong alkali treatment method, an oxidant treatment method, a coupling agent treatment method, and the like.
[0054]
The molded photosensitive resin composition is crosslinked by irradiation with light or an electron beam to form a resin plate. Moreover, it can also bridge | crosslink by irradiation of light or an electron beam, shape | molding. Among them, the method of crosslinking using light is preferable because it has advantages such as simple apparatus and high thickness accuracy. Examples of the light source used for curing include a high-pressure mercury lamp, an ultra-high pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp, and the curing can be performed by other known methods. Although the light source used for curing may be one type, the curability of the resin may be improved by curing using two or more types of light sources having different wavelengths, so two or more types of light sources may be used. There is no problem.
[0055]
The thickness of the printing original plate used for laser engraving may be arbitrarily set according to the purpose of use, but is generally in the range of 0.1 to 7 mm when used as a printing plate. In some cases, a plurality of materials having different compositions may be stacked.
In the present invention, a cushion layer made of an elastomer can be formed below the layer to be laser engraved. In general, since the thickness of the layer to be laser engraved is 0.1 to several mm, the other lower layers may be made of materials having different compositions. The cushion layer is preferably an elastomer layer having a Shore A hardness of 20 to 70 degrees. When the Shore A hardness is 20 degrees or more, the printing quality can be ensured because the film is appropriately deformed. Moreover, if it is 70 degrees or less, it can play the role as a cushion layer. A more preferable range of Shore A hardness is 30 to 60 degrees.
[0056]
The cushion layer is not particularly limited, and any cushion layer may be used as long as it has rubber elasticity, such as a thermoplastic elastomer, a photocurable elastomer, and a thermosetting elastomer. It may be a porous elastomer layer having nanometer-level micropores. In particular, from the viewpoint of processability to a sheet-like or cylindrical resin plate, it is convenient and preferable to use a photosensitive resin composition that is cured by light and to use a material that becomes elastomer after curing. From the viewpoint of molding into a sheet-like or cylindrical resin plate, it is particularly preferable to use a liquid photosensitive resin composition.
[0057]
Specific examples of the thermoplastic elastomer used for the cushion layer include SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-polystyrene), which are styrenic thermoplastic elastomers, and the like. 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.
[0058]
Examples of the photocrosslinkable elastomer include those obtained by mixing the thermoplastic elastomer with a photopolymerizable monomer, a plasticizer, a photopolymerization initiator, and the like, and a liquid composition in which a plastomer resin is mixed with a photopolymerizable monomer, a photopolymerization initiator, and the like. Can be mentioned. In the present invention, unlike the design concept of the photosensitive resin composition, in which the function of forming a fine pattern is an important element, it is not necessary to form a fine pattern using light, and by curing by overall exposure, Since it is sufficient to ensure a certain level of mechanical strength, the degree of freedom in selecting a material is extremely high.
[0059]
Moreover, non-sulfur cross-linked rubbers such as sulfur cross-linked rubber, organic peroxide, phenol resin initial condensate, quinone dioxime, metal oxide, and thiourea can also be used. Furthermore, it is also possible to use a three-dimensionally crosslinked elastomer obtained by using a curing agent that reacts with a telechelic liquid rubber.
In the case of multilayering in the present invention, the position of the back film is below the cushion layer, that is, at the bottom of the printing original plate, or between the photosensitive resin layer capable of laser engraving and the cushion layer, that is, on the printing original plate. It does not matter at any position in the center.
Further, by forming a modified layer on the surface of the laser engraving printing plate of the present invention, the tack of the printing plate surface can be reduced and the ink wettability can be improved. Examples of the modified layer include a film treated with a compound that reacts with a surface hydroxyl group such as a silane coupling agent or a titanium coupling agent, or a polymer film containing porous inorganic particles.
[0060]
A widely used silane coupling agent is a compound having in its molecule a functional group highly reactive with the surface hydroxyl group of the substrate. Examples of such a functional group include a trimethoxysilyl group and a triethoxysilyl group. Group, trichlorosilyl group, diethoxysilyl group, dimethoxysilyl group, dimonochlorosilyl group, monoethoxysilyl group, monomethoxysilyl group, monochlorosilyl group. Further, at least one of these functional groups exists in the molecule, and is immobilized on the surface of the base material by reacting with the surface hydroxyl group of the base material. Further, the compound constituting the silane coupling agent of the present invention is selected from acryloyl group, methacryloyl group, active hydrogen-containing amino group, epoxy group, vinyl group, perfluoroalkyl group, and mercapto group as reactive functional groups in the molecule. Those having at least one functional group or those having a long-chain alkyl group can be used.
[0061]
Examples of titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (di-tridecyl phosphite) titanate, Tetra (2,2-diallyloxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate, bis (octylpyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyl Dimethacrylisostearoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropylisostearoyl diacryl titanate Over DOO, isopropyl tri (dioctyl sulfate) titanate, isopropyl tricumylphenyl titanate, tetraisopropyl bis (dioctyl phosphite) may include compounds such as titanates.
[0062]
When the coupling agent molecule immobilized on the surface has a polymerizable reactive group in particular, it is possible to obtain a stronger coating by irradiating light, heat, or an electron beam and crosslinking after immobilization on the surface. .
In the present invention, the above-described coupling agent is diluted with water-alcohol or acetic acid water-alcohol mixed solution as necessary. The concentration of the coupling agent in the treatment liquid is preferably 0.05 to 10.0% by weight.
[0063]
The coupling agent treatment method in the present invention will be described. The treatment liquid containing the coupling agent is applied to the printing original plate or the surface of the printing plate after laser engraving. The method for applying the coupling agent treatment liquid is not particularly limited, and for example, an immersion method, a spray method, a roll coating method, a brush coating method, or the like can be applied. Further, the coating treatment temperature and the coating treatment time are not particularly limited, but are preferably 5 to 60 ° C., and the treatment time is preferably 0.1 to 60 seconds. Furthermore, it is preferable to dry the treatment liquid layer on the surface of the resin plate under heating, and the heating temperature is preferably 50 to 150 ° C.
[0064]
Before treating the printing plate surface with a coupling agent, a method of irradiating light in a vacuum ultraviolet region with a wavelength of 200 nm or less such as a xenon excimer lamp, or by exposing it to a high energy atmosphere such as plasma, a hydroxyl group on the printing plate surface. And the coupling agent can be immobilized at a high density.
In addition, when the layer containing inorganic porous particles is exposed on the printing plate surface, it is treated in a high-energy atmosphere such as plasma, and the organic layer on the surface is slightly etched away to remove minute particles on the printing plate surface. Unevenness can be formed. By this treatment, the effect of improving the ink wettability can be expected by reducing the tack of the printing plate surface and making the inorganic porous particles exposed on the surface easy to absorb the ink.
[0065]
In order to protect the surface of the produced printing original plate, it may be covered with a thin film made of polyethylene terephthalate or polypropylene. When laser engraving is used, the film is peeled off.
In laser engraving, a relief image is created on an original by operating a laser device using a computer as an image to be formed as digital data. Laser engraving is carried out in an oxygen-containing gas, generally in the presence of air or an air stream, but can also be carried out in the presence of carbon dioxide or nitrogen gas. After engraving is finished, the powdery or liquid substance slightly generated on the relief printing plate surface is washed with an appropriate method such as water containing a solvent or a surfactant, or a water-based cleaning agent is irradiated by a high-pressure spray or the like. Alternatively, it may be removed using a method of irradiating high-pressure steam.
[0066]
The printing original plate of the present invention is a relief image for a printing plate, a stamp / stamp, a design roll for embossing, a resistor used for creating an electronic component, a relief image for patterning a conductive paste, a relief image for a mold material of ceramic products It can be applied to various uses such as relief images for displays such as advertisements and display boards, and prototypes and master molds of various molded products.
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not restrict | limited by these.
[0067]
In the examples and comparative examples, laser engraving is performed using a laser engraving machine (trademark “Flexo Laser Setter WFL40-2V” manufactured by Wetzell Co., Ltd.) equipped with a YAG laser, and the engraving pattern is halftone dots and convexes having a width of 500 μm. A pattern including a line drawing by a line and a white line having a width of 500 μm was created and carried out. The engraving depth was 0.55 mm. The oscillation wavelength of the YAG laser was 1.06 μm.
[0068]
After laser engraving, the residue on the relief printing plate was wiped off using a nonwoven fabric impregnated with ethanol or acetone (trade name “BEMCOT M-3” manufactured by Asahi Kasei Corporation). The weights of the printing original plate before laser engraving, the printing plate immediately after laser engraving, and the relief printing plate after wiping were measured, and the residue rate at the time of engraving was determined by the formula (1).
(Weight of plate immediately after engraving-Weight of plate after wiping) ÷ (Weight of original plate before engraving-Weight of plate after wiping) x 100 (1)
[0069]
Further, tack measurement of the relief printing plate surface after wiping was performed using a tack tester manufactured by Toyo Seiki Seisakusho. Tack measurement was performed at 20 ° C. by contacting a smooth portion of a sample piece with a portion of an aluminum ring having a radius of 50 mm and a width of 13 mm, applying a load of 0.5 kg to the aluminum ring and leaving it for 4 seconds. The aluminum ring is pulled up at a constant speed of 30 mm and the resistance force when the aluminum ring is separated from the sample piece is read with a push-pull gauge. The larger this value, the greater the stickiness.
Further, among the engraved parts, the shape of a halftone dot part having an area ratio of about 10% at 80 lpi (Lines per inch) was observed with an electron microscope.
[0070]
[Production Example 1]
A mixture prepared by mixing propylene glycol, diethylene glycol, adipic acid, fumaric acid, and isophthalic acid in a molar ratio of 0.12 / 0.38 / 0.24 / 0.14 / 0.12 was heated in a nitrogen atmosphere. The degree of vacuum in the system was increased with a vacuum pump, and a liquid unsaturated polyester resin (A) was obtained by a water condensation reaction in which water was removed from the system. The number average molecular weight in terms of polystyrene was 2500 according to GPC measurement.
[0071]
Examples 1-5, Comparative Example 1
Using the unsaturated polyester resin (a) produced in Production Example 1, as shown in Table 1, the trademark “Pyrospher C-1504”, which is a polymerizable monomer, manufactured by Fuji Silysia Chemical Ltd., is a porous fine powder silica. (Hereinafter abbreviated as C-1504, number average particle diameter 4.5 μm, specific surface area 520 m ² / g, average pore diameter 12 nm, pore volume 1.5 ml / g, ignition loss 2.5 wt%, oil absorption 290 ml / 100 g) Trademark “Silicia 450” (hereinafter abbreviated as C-450, number average particle diameter 8.0 μm, specific surface area 300 m ² / g, average pore diameter 17 nm, pore volume 1.25 ml / g, loss on ignition 5.0 wt%, oil absorption 200 ml / 100 g), trade mark "Sylysia 470" (hereinafter abbreviated C-470, number average particle diameter of 14.1, a specific surface area of 300m ² / g, average pore diameter 17 nm, pore volume 1. 5 ml / g, ignition loss 5.0 wt%, oil absorption of 180 ml / 100 g), a photopolymerization initiator, the addition of other additives to create a resin composition. These are formed into a sheet having a thickness of 2.8 mm on a PET film, and then subjected to a relief surface of 2000 mJ / cm ² and a back surface of 1000 mJ / cm ² using an ALF type 213E exposure machine manufactured by Asahi Kasei Corporation. And a resin plate was produced.
[0072]
Next, the resin plate produced as described above was immersed in a treatment solution containing a pigment at 50 ° C. for 12 hours to form a dyed layer. In Examples 1 to 3 and Comparative Example 1, the pigment used was “Kayakaran Black 2RL” manufactured by Nippon Kayaku Colors Co., Ltd., and “Kayakaran Black BGL” was used for Examples 4 and 5. These dyes were dissolved in water at 1 wt% to prepare a dyeing solution.
The light transmittance at a wavelength of 1.06 μm of the dyed printing original plate was less than 1% in any of Examples 1 to 5 and Comparative Example 1. A spectrophotometer (manufactured by Shimadzu Corporation, trademark “UV-3150”) was used for the measurement of light transmittance. Moreover, as a result of cutting each sample and observing the cut surface with a microscope, the thickness of the layer dyed black was 1.5 mm or more.
[0073]
These were engraved with a YAG laser engraving machine. The evaluation results are shown in Table 2.
The number of wiping off the residue after engraving in Table 2 is the number of times of wiping treatment required to remove the viscous liquid residue generated after engraving. If this number is large, the amount of liquid residue is large. To do.
[0074]
For Example 1, the concentration distribution of the dye in the cross section of the printing original plate was measured. Using a microtome, sections were prepared in a direction parallel to the cross section at a low temperature. The thickness of the section was 1 mm. The concentration distribution of the dye was measured by irradiating measurement light from a direction perpendicular to the cross section of the printing original plate and measuring the light intensity transmitted through the section. The measurement area was 20 μmφ, and the change in transmittance was compared by shifting the measurement position in the depth direction from the surface of the printing original plate irradiated with the laser. The apparatus used for the measurement was a microscope spectrophotometer (trademark “U-6500” manufactured by Hitachi High-Technologies Corporation), and the wavelength of light used for the measurement was 700 nm. The dye used for dyeing showed light absorption even at 700 nm. As a result of the measurement, the light transmittance in the vicinity of the surface irradiated with the laser was less than 1%, but the light transmittance at a portion of 1.5 mm in the depth direction was 20% or more. Therefore, it was confirmed that the dye concentration distribution in the dyed layer was a concentration distribution that decreased in the depth direction of the printing original plate.
Of the organic compound (b) containing a double bond used in the examples of the present invention, the alicyclic and aromatic derivatives are BZMA, CHMA and PEMA.
[0075]
[Comparative Example 2]
A printing original plate was prepared in the same manner as in Example 1 except that organic porous spherical fine particles were used. The organic porous fine particles were made of crosslinked polystyrene, and were fine particles having a number average particle diameter of 8 μm, a specific surface area of 200 m ² / g, and an average pore diameter of 50 nm.
After engraving with a YAG laser, a large amount of viscous liquid residue was generated, and the number of times of residue wiping was required to exceed 30 times. This is presumed that the organic porous fine particles were melted and decomposed by laser light irradiation, and the porous property could not be maintained.
[0076]
[Table 1]

[0077]
[Table 2]

[0078]
【The invention's effect】
According to the present invention, when the relief image is produced by direct laser engraving with sufficient hardness up to the inside of the plate, not only can the generation of debris be suppressed and the debris can be easily removed, A printing original plate capable of near-infrared laser engraving capable of producing a printing plate having an excellent engraving shape and a small printing surface tack can be provided. The present invention is particularly useful for engraving using a laser beam in the near-infrared region, which cannot be used with a normal resin plate because it absorbs little light.

Claims (11)

A printing original plate comprising a cured layer of a sheet-shaped or cylindrical laser-engravable photosensitive resin composition, the cured layer containing an inorganic porous material (c) and irradiated with laser light from the surface side to the depth direction, having a dyeing layer cured layer is stained with a dye having a light absorption at the wavelength of the laser beam, and wherein the thickness of該染color layer is 0.01mm or more Laser engraving printing master.   The laser engraving printing original plate according to claim 1, wherein the dye has light absorption in a near infrared region of 700 nm to 2 μm.   The laser engraving printing original plate according to claim 1 or 2, wherein the dye has a reactive functional group.   The laser engraving printing original plate according to any one of claims 1 to 3, wherein the concentration distribution of the dye in the dyed layer decreases in the depth direction from the surface of the printing original plate.   5. The light transmittance measured by transmitting light from a direction perpendicular to a printing original plate dyed with a dye is 10% or less at a wavelength of a laser beam used for laser engraving. The laser engraving printing original plate as described in Crab. The photosensitive resin composition is a resin (a) having a number average molecular weight of 1,000 to 200,000, an organic compound (b) having a polymerizable unsaturated group having a number average molecular weight of less than 1,000, a specific surface area of 10 m ² / g or more and 1500 m ² / g. And an inorganic porous body (c) having an average pore diameter of 1 nm to 1000 nm, a pore volume of 0.1 ml / g to 10 ml / g, and an oil absorption of 10 ml / 100 g to 2000 ml / 100 g. The laser engraving printing original plate according to claim 1.   The laser engraving printing original plate according to claim 6, wherein 20 wt% or more of the total amount of the organic compound (b) is at least one alicyclic or aromatic derivative.   The number average particle diameter of the inorganic porous material (c) is 0.1 μm or more and 100 μm or less, and at least 70% of the particles are spherical particles having a sphericity of 0.5 to 1. Item 7. The laser engraving printing original plate according to Item 6.   (I) a step of laminating a photosensitive resin composition layer on a sheet-like or cylindrical support, (ii) a step of irradiating and curing light on the entire surface of the formed photosensitive resin composition layer, (iii) obtained A method for producing a laser engraving printing original plate, comprising a step of dyeing the laminate into the resin plate by dyeing the laminate.   A multilayer laser engraving printing original plate comprising at least one elastomer layer having a Shore A hardness of 20 or more and 70 or less at a lower portion of the printing original plate according to claim 1.   The multilayer laser engraving printing original plate according to claim 10, wherein the elastomer layer is formed by curing a photosensitive resin composition.