JP2004174757A - Laser engraved printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexographic plate on which generation of a residue is suppressed when a relief image is directly engraved by laser, the residue can be easily removed, a shape of engraving is excellent, and tack of a printed surface is small. <P>SOLUTION: In this printing plate, an uneven pattern is formed by applying laser to a layer composed of a photo-cured material of a photosensitive resin composition for laser engraving. After wiping off the engraving residue generated by the laser engraving, inorganic porous particles exist in an exposed state on the surface of an engraved part engraved by laser irradiation. When elementary analysis on the surface is performed by a fluorescent X-ray method, the value of the expression, (Ie/Ic)/(Ie0/Ic0), is 1.5 or more. In the expression, Ie represents the characteristic X-ray intensity of a specific element in the inorganic porous body particulate detected from the surface of the carved part; Ic represents the characteristic X-ray intensity of carbon detected from the surface of the carved part; Ie0 represents the characteristic X-ray intensity of the specific element detected from the surface of an unengraved part; and Ic0 represents the characteristic X-ray intensity of carbon detected from the surface of the unengraved part. <P>COPYRIGHT: (C)2004,JPO

Description

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【表２】

【００８５】
【表３】

【００８６】
【発明の効果】
本発明により、直接レーザー彫刻してレリーフ画像を制作する際の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、彫刻レリーフの形状が優れ、印刷面のタックが小さいフレキソ印刷版を提供できる。
【図面の簡単な説明】
【図１】実施例１の彫刻部表面の走査型電子顕微鏡写真。
【図２】実施例１の網点部のパターン形状を示す電子顕微鏡写真。
【図３】実施例３の網点部のパターン形状を示す電子顕微鏡写真。
【図４】実施例１のドットパターン形状を示す電子顕微鏡写真。
【図５】実施例３のドットパターン形状を示す電子顕微鏡写真。[0001]
[Technical field to which the present invention pertains]
The present invention is applicable to the formation of relief images for flexographic printing plates by laser engraving, the formation of patterns for surface processing such as embossing, the formation of relief images for printing tiles, etc., and the formation of electronic circuits consisting of patterns such as conductors, semiconductors and insulators. It concerns a suitable laser engraving printing plate.
[0002]
[Prior art]
Flexographic printing used for packaging materials such as cardboard, paper containers, paper bags, flexible packaging films, etc., building materials such as wallpaper and decorative boards, and label printing has been increasing its specific gravity among various printing methods. For the production of the printing plate used for this, usually a photosensitive resin is often used, a liquid resin, or a solid resin plate molded into a sheet, using a photomask placed on the photosensitive resin, the mask After irradiating light to cause a crosslinking reaction, a method of washing off a non-crosslinked portion with a developer has been used. In recent years, a thin light-absorbing layer called a black layer was provided on the surface of a photosensitive resin, and a laser beam was irradiated on the layer to form a mask image directly on the photosensitive resin plate. Then, light was irradiated through the mask to cause a crosslinking reaction. Later, a technique called flexo CTP (Computer to Plate) in which a non-crosslinked portion of a non-irradiated portion is washed away with a developing solution has been developed, and its adoption is being promoted due to an effect of improving the efficiency of printing plate production. However, this technology also has a limited efficiency improvement effect, such as the remaining development process, and there is a need for the development of a technology that forms a relief image directly on a printing original plate using a laser and that does not require development. .
[0003]
As a method therefor, there is a method of directly engraving a printing original plate with a laser. The production of letterpress printing plates and stamps by this method has already been performed, and the materials used for the printing plates and stamps are also known.
Japanese Patent Application Laid-Open No. 2001-121833 (European Patent Publication No. 1080883) discloses that silicone rubber is used and carbon black is mixed therein as an absorber of a laser beam, but it does not use a photosensitive resin. It is produced by a process of mixing a laser beam absorber before forming into a sheet. The printing original plate formed from the crosslinked rubber has a problem that the engraving speed is slow because it is hard to be melted or decomposed by the irradiation of the laser beam, and the engraving residue is burned to make it difficult to remove.
[0004]
On the other hand, Japanese Patent Nos. 2,846,954 and 2,846,955 (U.S. Pat. Nos. 5,798,202 and 5,804,353) use a material obtained by mechanically, photochemically, and thermochemically strengthening a thermoplastic elastomer such as SBS, SIS, or SEBS. It is disclosed. When using a thermoplastic elastomer, if engraving is performed using a laser having an oscillation wavelength in the infrared region, heat will melt the resin up to the part that largely deviates from the laser beam diameter, resulting in a high-resolution engraving pattern. Cannot be formed. Therefore, it is essential to mechanically strengthen the thermoplastic elastomer layer by adding a filler. In the above patent, a large amount of carbon black, which has a particularly high mechanical reinforcing effect, is mixed for the purpose of mechanically reinforcing the thermoplastic elastomer layer and improving the absorption of laser light.
[0005]
Generally, a method of mixing black carbon black, a dye, and the like in a resin and then forming the mixture into a sheet is used. However, in this method, since carbon black or a dye has light absorption in an ultraviolet region, when a photosensitive resin composition is photocured using light in an ultraviolet region or a visible light region to secure mechanical strength, a plate is required. There was a major problem that the internal curing was insufficient. In other words, when laser engraving a printing master plate with insufficient photocuring, a large amount of scum (including a liquid viscous material) that is difficult to remove is generated, and not only takes a lot of time to process, but also melts into relief. This causes difficulties such as the swelling of the edge portion, the fusion of solid waste at the edge portion, and the collapse of the halftone dot shape. There is also a problem that a large amount of generally harmful carbon black is released into the atmosphere.
[0006]
In addition, when a large amount of viscous liquid scum, which is presumed to be a decomposition product of the resin during laser engraving, is generated, not only does the optical system of the laser device become dirty, but also on the surface of optical components such as lenses and mirrors. The attached liquid resin causes seizure, which is a major cause of trouble on the apparatus. In addition, a large amount of viscous liquid residue also exists on the surface of the portion removed by laser irradiation, and if the removal is insufficient, paper dust or the like during printing tends to adhere and accumulate. It may cause trouble in the process.
[0007]
[Patent Document 1]
JP 2001-121833 A
[Patent Document 2]
Japanese Patent No. 2846954
[Patent Document 3]
Japanese Patent No. 2,846,955
[0008]
[Problems to be solved by the invention]
The present invention suppresses the generation of scum when producing a relief image by direct laser engraving, and not only can the scum be easily removed, but also the flexographic printing having an excellent engraved relief shape and a small tack on the printing surface. To provide an edition.
[0009]
[Means for Solving the Problems]
The present inventors have studied diligently, and in a printing plate in which a sheet or cylindrical printing original plate formed by photo-curing a photosensitive resin composition containing an inorganic porous body is engraved with a laser beam, engraving residue, particularly It has been found that there is little liquid residue and that the tack of the surface of the portion where the cured resin is removed by engraving and the tack of the surface of the non-engraved portion are small. When the surface of the portion where the resin cured product was removed by the irradiation of the laser beam was analyzed, the added inorganic porous fine particles were exposed on the surface, and were present in a large amount, and the inorganic porous fine particles were concentrated. The discovery of the presence of such a layer led to the completion of the present invention. In addition, since the inorganic porous material fine particles which are exposed on the surface and exist in a large amount are fixed on the surface, they remain on the surface without being removed in the step of removing engraving residue.
[0010]
In particular, in a printing original plate formed by photo-curing a photosensitive resin composition, when a pigment or dye such as carbon black is added, the light transmittance in the ultraviolet or visible light region used for photo-curing becomes low. For this reason, the inside of the printing original plate is insufficiently cured, and there is a fatal problem that a large amount of liquid residue is generated. However, the present invention is a breakthrough that can solve these problems. .
The present invention is as follows.
[0011]
1. A printing plate made of a photo-cured product of a photosensitive resin composition having a concavo-convex pattern formed by irradiating a laser beam, with the inorganic porous material fine particles being exposed on the surface of the engraved portion removed by the laser beam irradiation. When the element is present and the elemental analysis of the surface is performed using the X-ray fluorescence method, the characteristic X-ray intensity Ie of the specific element and the characteristic X Intensity ratio with the line intensity Ic and characteristic X-ray intensity Ie of the specific element detected from the surface of the unengraved portion₀X-ray intensity Ic of carbon and carbon₀(Ie / Ic) / (Ie)₀/ Ic₀A) a laser engraving printing plate, wherein the value of (1) is 1.5 or more.
[0012]
2. Inorganic porous fine particles contained in the cured photosensitive resin have a specific surface area of 10 m²/ G or more and 1500m²/ G or less, an average pore diameter of 1 nm or more and 1000 nm or less, a pore volume of 0.1 ml / g or more and 10 ml / g or less, and an oil absorption of 10 ml / 100 g or more and 2000 ml / 100 g or less. The laser engraving printing plate described in 1.
3. The photosensitive resin composition contains a resin (a) having a number average molecular weight of 1,000 to 500,000 and an organic compound (b) having a polymerizable unsaturated group having a number average molecular weight of less than 1,000. Or 2. The laser engraving printing plate described in 1.
[0013]
4. 2. 20% by weight or more of the total amount of the organic compound (b) is at least one kind of an alicyclic or aromatic derivative. The laser engraving printing plate described in 1.
5. 2. The inorganic porous fine particles are spherical particles in which the number average particle diameter is 0.1 μm or more and 100 μm or less, and the sphericity of at least 70% of the particles is in the range of 0.5 to 1. Or 4. The laser engraving printing plate described in 1.
6. 1. To 5. A multilayer laser engraving printing plate having at least one elastomer layer having a constant thickness of 20 to 70 degrees in a lower portion of the printing plate according to any one of the above.
7. 5. The elastomer layer is formed by curing the liquid photosensitive resin composition at 20 ° C. The multi-layer laser engraving printing plate described in 1.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail mainly on preferred embodiments.
In the present invention, a photosensitive resin composition containing inorganic porous material fine particles is photo-cured to form a laser-engravable printing original plate, and thereafter, the printing original plate is irradiated with a laser beam to irradiate the laser-irradiated portion. By removing the resin, an uneven pattern is formed, and a printing plate can be manufactured. On the surface of the engraved portion (concave portion) removed by laser beam irradiation, inorganic porous fine particles are exposed and exist. The situation in which the inorganic porous material fine particles are exposed on the surface can be easily confirmed by observation using a scanning electron microscope. It is preferable to use the fluorescent X-ray method for analyzing the surface where the inorganic porous material fine particles are exposed. The fluorescent X-ray method is a surface analyzer that can quantitatively analyze the existing elements by irradiating a sample with X-rays and analyzing emitted characteristic X-rays. The depth of the information obtained by the analysis is about 50 μm from the surface. When performing quantitative analysis by this method, the intensity of the irradiated X-rays and the intensity of the detected characteristic X-rays change due to the measurement conditions such as the degree of vacuum and the shape of the sample surface. It is common to handle the ratio of the characteristic X-ray intensity of the particular element of interest to the characteristic X-ray intensity of the target. In the present invention, the ratio of the characteristic X-ray intensity of the specific element present in the inorganic porous material fine particles to the characteristic X-ray intensity emitted from carbon in the resin is handled. Furthermore, in the present invention, the characteristic X-ray intensity of the specific element in the inorganic porous material fine particles detected from the surface of the laser engraved portion is set to Ie, and the characteristic X-ray intensity of carbon is set to Ic, and the characteristic X-ray intensity is detected from the surface of the unengraved portion. The characteristic X-ray intensity of the specific element₀And the characteristic X-ray intensity of carbon₀When (Ie / Ic) / (Ie₀/ Ic₀) Is 1.5 or more, more preferably 2.6 or more, and still more preferably 4 or more. (Ie / Ic) / (Ie₀/ Ic₀If the value of ()) is not less than 1.5, the effect of reducing the tack on the surface of the engraved portion and the non-engraved portion from which the resin has been removed can be seen.
[0015]
In the present invention, the mechanism by which the inorganic porous material fine particles are exposed on the surface is not well understood, but since the cured product of the photosensitive resin composition is easily decomposed, the amount of the inorganic porous material fine particles scattered outside the system is small, and It is presumed that they remain and accumulate in Further, the inorganic porous fine particles absorb liquid scum which is a decomposition product of the resin in the printing original plate. Further, it is considered that the resin is partially melted by the heat of the laser irradiation, and then the inorganic porous fine particles are fixed on the surface during the cooling process. Further, it is considered that some of the inorganic fine particles are scattered during the laser engraving and adhere to the surface of the non-engraved portion. However, the fine particles once adhered are not removed by the process of wiping using a cloth impregnated with a solvent such as alcohol or by irradiation with high-pressure steam, etc., and remain on the surface. Is presumed to be seen.
[0016]
The resin constituting the printing original plate of the present invention is preferably a resin obtained by photo-curing a photosensitive resin composition from the viewpoint of processability into a sheet or cylindrical printing original plate. Examples of a method for photo-curing the photosensitive resin include a method of irradiating ultraviolet rays or visible light in a range of 200 nm to 600 nm or a method of irradiating an electron beam. In the method of irradiating light, 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 cured without decomposing the resin, and a commercially available photopolymerization initiator can be used.
[0017]
Among the photosensitive resins that can be used in the present invention, the resin (a) preferably has a number average molecular weight in the range of 1,000 to 500,000. A more preferred range is 5000 to 100,000. When the number average molecular weight is in the range of 1,000 to 500,000, 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 by gel permeation chromatography (GPC) and evaluated with respect to a standard polystyrene sample having a known molecular weight.
[0018]
The type of the resin (a) may be an elastomeric resin or a non-elastomeric resin, and may be a solid resin or a liquid resin at 20 ° C. When a thermoplastic resin is used, the content is preferably 30% by weight or more, more preferably 50% by weight or more, and still more preferably 70% by weight or more of the total weight of the resin (a). When the content of the thermoplastic resin is 30% by weight or more, the resin is sufficiently fluidized by laser beam irradiation, and is absorbed by the inorganic porous material described later. However, when a resin having a softening temperature exceeding 350 ° C. is used, the temperature at which the resin is molded into a sheet or a cylinder is naturally high, and other organic substances may be denatured or decomposed by heat. With respect to a resin having a temperature exceeding ℃, a solvent-soluble resin may be applied and used in a state of being dissolved in a solvent.
[0019]
In particular, it is preferable to use a polymer liquid at 20 ° C. as the resin (a) from the viewpoint of ease of processing into a sheet or cylindrical resin plate and from the viewpoint of workability of a fine pattern. When a polymer which is liquid at 20 ° C. is used as the resin (a), the photosensitive resin composition to be formed is also liquid, so that it can be molded at a low temperature, as in the case where a thermoplastic elastomer or the like is used. Since it is not necessary to heat the resin to a high temperature to fluidize the resin, the apparatus can be simplified.
[0020]
As a technical feature of the present invention, it is possible to mention that scum liquefied by laser beam irradiation is absorbed and removed by using inorganic porous fine particles. As a resin to be used, a resin which is easily liquefied or a resin which is easily decomposed is preferable. As the easily decomposable resin, styrene, α-methylstyrene, α-methoxystyrene, acrylic esters, methacrylic esters, ester compounds, ether compounds, nitro compounds, carbonates as monomer units which are easily decomposed in the molecular chain Preferably, compounds, oxyethylene compounds, aliphatic cyclic compounds and the like are contained. In particular, polyethylene glycol, polypropylene glycol, polyethers such as polytetraethylene glycol, aliphatic polycarbonates, polymethyl methacrylate, polystyrene, nitrocellulose, polyoxyethylene, polynorbornene, polycyclohexadiene hydrogenated, or branched structure Resins such as dendrimers are typical examples of those which are easily decomposed. Further, a resin containing a large number of oxygen atoms in the molecular chain is preferable from the viewpoint of decomposability. Among them, compounds having a carbonate group, a carbamate group, and a methacryl group in the polymer main chain are preferable because of high thermal decomposability. For example, polyesters and polyurethanes synthesized from (poly) carbonate diol and (poly) carbonate dicarboxylic acid as raw materials, polyamides synthesized from (poly) carbonate diamine as raw materials, and the like can be given as examples of polymers having good thermal decomposability. . These polymer main chains and side chains may contain a polymerizable unsaturated group. In particular, when the terminal has a reactive functional group such as a hydroxyl group, an amino group, or a carboxyl group, it is easy to introduce a polymerizable unsaturated group into the terminal of the main chain.
[0021]
As an index for measuring the ease of decomposition of the resin, there is a weight reduction rate when the photocured product of the above photosensitive resin composition is subjected to thermogravimetric analysis under a nitrogen atmosphere. As the resin (a) used in the present invention, the temperature at which the weight loss rate after photocuring is 50 wt% is preferably 150 ° C. or more and 400 ° C. or less, more preferably 200 ° C. or more and 380 ° C. or less. If the temperature at which the weight loss rate is 50% is 150 ° C. or higher, the resin can be easily processed without decomposing the resin in the step of molding into a sheet or a cylinder. Can be sufficiently decomposed.
[0022]
Although not particularly limited, the thermoplastic elastomer used in the present invention is a styrene-based thermoplastic elastomer such as SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), and SEBS (polystyrene-polyethylene / polybutylene-). Polystyrene), olefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, ester-based thermoplastic elastomer, amide-based thermoplastic elastomer, silicone-based thermoplastic elastomer, and the like. The number-average molecular weight is preferably 100,000 or less, More preferably, it is 50,000 or less. In order to further improve the thermal decomposability, 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 a main chain in a molecular skeleton can be used. 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 fine particles used in the present invention. The thermoplastic elastomer is a material which flows by heating, can be molded in the same manner as ordinary thermoplastics, 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, similar to vulcanized rubber. The hard segments are a frozen phase, a crystalline phase, hydrogen bonds, and ionic crosslinks. There are various types.
[0023]
The type of thermoplastic elastomer can be selected depending on the use of the printing plate. For example, in fields where solvent resistance is required, urethane-based, ester-based, amide-based, and fluorine-based thermoplastic elastomers are preferred.In fields where heat resistance is required, urethane-based, olefin-based, ester-based, and fluorine-based thermoplastic elastomers are preferred. Plastic elastomers are preferred. Further, the hardness can be largely changed depending on the type of the thermoplastic elastomer. In the application of a normal printing plate, a region having a Shore A hardness of 20 to 75 degrees is preferable, and a paper, a film, and an embossing application for forming a surface uneven pattern of a building material require a relatively hard material. The range of 30 to 80 degrees in Shore D hardness is preferable.
[0024]
Non-elastomeric thermoplastic resins include, but are not particularly limited to, polyester resins, unsaturated polyester resins, polyamide resins, polyamideimide resins, polyurethane resins, unsaturated polyurethane resins, polysulfone resins, polyethersulfone resins, Polyimide resins, polycarbonate resins, wholly aromatic polyester resins and the like can be mentioned.
[0025]
The softening temperature of the thermoplastic resin of the present invention is preferably from 50 ° C to 300 ° C, more preferably from 80 ° C to 250 ° C, and still more preferably from 100 ° C to 200 ° C. If the softening temperature is 50 ° C. or higher, it can be handled as a solid at room temperature, and a sheet or a cylinder can be handled without deformation. When the softening temperature is 500 ° C. or lower, it is not necessary to heat to an extremely high temperature when processing into a sheet or a cylinder, and it is not necessary to alter or decompose other compounds to be mixed. The measurement of the softening temperature of the present invention uses a dynamic viscoelasticity measuring device, and is defined as the first temperature at which the viscosity changes greatly (the slope of the viscosity curve changes) when the temperature is increased from room temperature. I do.
[0026]
Further, the resin (a) of the present invention may be a solvent-soluble resin. Specific examples include a polysulfone resin, a polyimide resin, a polyethersulfone resin, an epoxy resin, a bismaleimide resin, a novolak resin, an alkyd resin, a polyolefin resin, and a polyester resin.
[0027]
The resin (a) usually does not have a highly reactive polymerizable unsaturated group in many cases, but may have a highly reactive polymerizable unsaturated group at a terminal or a side chain of a molecular chain. When a resin (a) having a polymerizable unsaturated group having high reactivity is used, a printing original plate having extremely high mechanical strength can be produced. Particularly, in the case of a polyurethane-based or polyester-based thermoplastic elastomer, it is possible to relatively easily introduce a highly reactive polymerizable unsaturated group into the molecule. 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, or in the polymer main chain or in the side chain. For example, those in which a polymerizable unsaturated group is directly introduced at the molecular end thereof may be used. Alternatively, a hydroxyl group, an amino group, an epoxy group, a carboxyl group, an acid anhydride group, a ketone group, a hydrazine residue may be used. A binder having a plurality of groups having a plurality of reactive groups such as an isocyanate group, an isothiocyanate group, a cyclic carbonate group, and an ester group and having a molecular weight of about several thousand and capable of binding to the above-mentioned components (for example, a hydroxyl group and an amino group) ), The molecular weight is adjusted, and the terminal is converted to a terminal bonding group. Then, the group reacting with the terminal bonding group and the organic compound having a polymerizable unsaturated group are reacted. Then, a method such as a method of introducing a polymerizable unsaturated group into a terminal is preferably used.
[0028]
The organic compound (b) is a compound having a radical or an unsaturated bond involved in an addition polymerization reaction. The number average molecular weight is preferably 1,000 or less in consideration of the ease of dilution with the resin (a). Examples of the organic compound (b) include those having radical reactivity, such as olefins such as ethylene, propylene, styrene and divinylbenzene, acetylenes, (meth) acrylic acid and its derivatives, and unsaturated compounds such as haloolefins and acrylonitrile. Nitriles, (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 -Vinyl carbazole, cyanate esters, etc., and (meth) acrylic acid and its derivatives are preferred examples from the viewpoint of abundance of the types, price, and the like. Compounds having addition polymerization reactivity include compounds having a cinnamoyl group, a thiol group, and an azide group, and those having ring-opening addition polymerization reactivity include an epoxy group, an oxetane group, and a cyclic ester group. And compounds having a dioxirane group, a spiroorthocarbonate group, a spiroorthoester group, a bicycloorthoester group, a cyclosiloxane group, a cyclic iminoether group, and the like.
[0029]
The derivative may be an alicyclic group such as cycloalkyl-, bicycloalkyl-, cycloalkene- or bicycloalkene-, an aromatic group such as benzyl-, phenyl-, or phenoxy-, an alkyl-, a halogenated alkyl-, an alkoxyalkyl-, or the like. Esters of polyhydric alcohols such as hydroxyalkyl-, aminoalkyl-, tetrahydrofurfuryl-, allyl-, glycidyl-, alkylene glycol-, polyoxyalkylene glycol-, (alkyl / allyloxy) polyalkylene glycol- and trimethylolpropane Is raised.
[0030]
Further, a compound having a molecular structure with good thermal decomposability can be used as the organic compound (b). For example, the use of an organic compound (b) having a molecular structure with high thermal decomposability, such as a carbonate group or a carbamate group, is effective as a method for improving the thermal decomposability of a photocured product.
In the present invention, one or more of these organic compounds (b) having a polymerizable unsaturated bond can be selected according to the purpose. For example, when used as a printing plate, having at least one or more long-chain aliphatic, alicyclic or aromatic derivatives as organic compounds used to suppress swelling of organic solvents such as alcohols and esters as printing ink solvents. Is preferred.
[0031]
In order to increase the mechanical strength of the printing plate precursor obtained from the resin composition of the present invention, it is preferable that the organic compound (b) has at least one alicyclic or aromatic derivative. It is preferably at least 20 wt% of the total amount of (b), more preferably at least 50 wt%.
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 the selection can be made by utilizing the technical knowledge of a known photosensitive resin for printing.
[0032]
Inorganic porous fine particles are inorganic particles that have fine pores or fine voids in the particles, and are additives for absorbing and removing viscous liquid residue generated in large quantities during laser engraving. Yes, it also has the effect of preventing tack on the plate. The inorganic porous material fine particles of the present invention are added for the purpose of removing viscous liquid residue for the greatest purpose, and the number average particle diameter, the specific surface area, the average pore diameter, the pore volume, and the ignition loss are large in its performance. Affect.
[0033]
In the present invention, it is preferable to use a resin that is easily cut by laser irradiation. In this case, a large amount of low-molecular monomers and oligomers are generated at the time of cutting the molecule. The most distinctive feature is that it introduces a new concept, which is completely unconventional in the existing technical ideas. Therefore, as described above, the physical properties such as the number average particle diameter, the specific surface area, the average pore diameter, the pore volume, the ignition loss, and the oil supply amount of the inorganic porous material fine particles containing porous silica used for removing the viscous liquid residue are removed. This is a very important factor.
[0034]
The inorganic porous fine particles preferably have a number average particle size of 0.1 to 100 μm. When a resin having a number average particle size smaller than this range is used, dust tends to fly when engraving an original plate obtained from the resin composition of the present invention with a laser, and the mixture with the resin (a) and the organic compound (b) is mixed. When performing, the viscosity tends to increase. On the other hand, when a particle having a number average particle diameter larger than the above range is used, the relief image is likely to be damaged when laser engraving is performed. A more preferable range of the average particle size is 0.5 to 20 μm, and a still more preferable range is 3 to 10 μm. The average particle size of the inorganic porous material fine particles of the present invention can be measured using a laser scattering type particle size distribution measuring device.
[0035]
The range of the specific surface area of the inorganic porous material fine particles used in the present invention is 10 m²/ G or more and 1500m²/ G or less. A more preferred range is 100 m²/ G or more and 800m²/ G or less. Specific surface area is 10m²/ G or more, the removal of liquid residue during laser engraving becomes sufficient, and²/ G or less can suppress an increase in the viscosity of the photosensitive resin composition, and can suppress thixotropy. The specific surface area of the present invention is determined from the adsorption isotherm of nitrogen at -196 ° C based on the BET equation.
[0036]
The average pore diameter of the inorganic porous material fine particles has an extremely large effect on the amount of liquid residue generated during laser engraving. The preferable range of the average pore diameter is 1 nm or more and 1000 nm or less, more preferably 2 nm or more and 200 nm or less, and further preferably 2 nm or more and 50 nm or less. When the average pore diameter is 1 nm or more, the absorbability of liquid scum generated during laser engraving can be ensured. When the average pore diameter is 1000 nm or less, the specific surface area of the particles is large and the liquid scum absorption amount can be sufficiently ensured. When the average pore diameter is less than 1 nm, it is not clear why the absorption amount of the liquid scum is small, but it is presumed that the liquid scum is viscous and hardly enters the micropores and the absorption amount is small. are doing. The average pore diameter in 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 the porous particles having mesopores to absorb liquid residue is extremely high. The pore size distribution of the present invention is determined from the adsorption isotherm of nitrogen at -196 ° C.
[0037]
The pore volume of the inorganic porous material fine particles 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 the pore volume is 10 ml / g or less, the mechanical strength of the particles can be secured. In the present invention, the pore volume is measured by a nitrogen adsorption method. The pore volume of the present invention is determined from the adsorption isotherm of nitrogen at -196 ° C.
[0038]
As an index for evaluating the amount of adsorbed liquid residue of the present invention, there is an oil absorption amount. This is defined by the amount of oil absorbed by 100 g of the inorganic porous material fine particles. The preferable range of the oil absorption of the inorganic fine particles 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. When the oil absorption is 10 ml / 100 g or more, the removal of liquid scum generated during laser engraving is sufficient, and when the oil absorption is 2000 ml / 100 g or less, the mechanical strength of the inorganic porous fine particles can be sufficiently ensured. The oil absorption was measured according to JIS-K5101.
[0039]
It is necessary that the inorganic fine particles of the present invention maintain their porosity 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% by weight or less, more preferably 10% by weight or less.
The particle shape of the inorganic porous material fine particles is not particularly limited, and spherical, flat, acicular, amorphous, or particles having protrusions on the surface can be used. Among them, spherical particles are particularly preferable from the viewpoint of abrasion resistance of the printing plate. Further, it is also possible to use particles having a hollow inside, spherical granules having a uniform pore diameter such as silica sponge, or the like. Although not particularly limited, examples thereof include porous silica, mesoporous silica, silica-zirconia porous gel, porous alumina, and porous glass. In addition, the pore size cannot be defined for a layer having a gap of several nm to 100 nm, such as a layered clay compound, in the present invention. Therefore, in the present invention, the gap between the gaps between the layers is defined as the pore diameter.
[0040]
Sphericity is defined as an index for defining spherical particles. The sphericity used in the present invention is the maximum value D of a circle that completely enters a projected figure when a particle is projected.₁, The minimum value D of the circle in which the projected figure completely fits₂Ratio (D₁/ D₂). In the case of a true sphere, the sphericity is 1.0. The sphericity of the preferred 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 abrasion resistance of the printing plate is good. The sphericity of 1.0 is the upper limit of the sphericity. It is desirable that 70% or more, more preferably 90% or more of the spherical particles have a sphericity of 0.5 or more. As a method for measuring sphericity, a method for measuring based on a photograph taken using a scanning electron microscope can be used. At this time, it is preferable to take a photograph at a magnification at which at least 100 or more particles enter the monitor screen. Further, the above D1 and D2 are measured based on the photograph, but it is preferable that the photograph is processed using a digitizing device such as a scanner, and then the data is processed using image analysis software.
[0041]
Further, organic pigments such as pigments and dyes that absorb light having a wavelength of laser light can be incorporated into these pores or voids. Further, the surface of the inorganic porous material fine particles may be coated with a silane coupling agent, a titanium coupling agent, or another organic compound and subjected to a surface modification treatment to make the particles more hydrophilic or hydrophobic.
In the present invention, one kind or two or more kinds of these inorganic porous material fine particles can be selected. By adding the inorganic porous material fine particles, the generation of liquid scum during laser engraving can be suppressed, and the tack of the relief printing plate can be reduced. Improvements such as prevention are effectively performed.
[0042]
The present inventors have introduced a new concept of porosity in evaluating the properties of a porous body. The porosity is determined by the average particle diameter D (unit: μm) and the density d of the substance constituting the particles (unit: g / cm³)), The ratio of the specific surface area P to the surface area S per unit weight, that is, P / S. The surface area S per unit weight is πD²× 10^{− 12}(Unit: m²) And the weight of the particles is (πD³d / 6) × 10^-12(Unit: g), S = 6 / (Dd) (unit: m²/ G). If the porous particles are not spherical, S is determined assuming a sphere in which the particle of interest completely enters, and the average value of the sphere diameter as the average particle diameter D. As the specific surface area P, a value measured by adsorbing nitrogen molecules on the surface is used.
[0043]
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, taking into account the particle size, porosity was adopted as a dimensionless index. The porosity of the inorganic porous material (c) used in the present invention is preferably 20 or more, more preferably 50 or more, and further preferably 100 or more. When the porosity is 20 or more, it is effective in removing and removing liquid residue.
[0044]
The porosity of the porous silica used in the examples of the present application is a high value well over 500.
The ratio of the resin (a), the organic compound (b), and the inorganic porous fine particles (c) in the photosensitive resin composition of the present invention is usually 100 parts by weight of the resin (a) and the organic compound (b). ) Is preferably from 5 to 200 parts by weight, more preferably from 20 to 100 parts by weight. The amount of the inorganic porous material fine particles is preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight. A more preferred range is from 2 to 20 parts by weight.
When the proportion of the organic compound (b) is smaller than the above range, inconveniences such as difficulty in achieving a balance between hardness and tensile strength and elongation of the obtained printing plate or the like are likely to occur. In this case, the shrinkage tends to increase, and the thickness accuracy tends to deteriorate.
[0045]
When the amount of the inorganic porous material particles is smaller than the above range, depending on the type of the resin (a) and the organic compound (b), a tack-preventing effect on the plate surface and the generation of engraved liquid residue when laser engraving is performed. In some cases, effects such as suppression of the printing plate may not be sufficiently exhibited, and when it is larger than the above range, the printing plate tends to be brittle. Further, the transparency may be impaired, and the hardness may be too high, especially when used as a flexographic plate. When a photosensitive resin composition is cured using light, particularly ultraviolet light, to produce a laser engraving printing original plate, the light transmission affects the curing reaction. Therefore, it is effective to use an inorganic porous material fine particle having a refractive index close to that of the photosensitive resin composition.
[0046]
As a method of mixing the inorganic porous material in the photosensitive resin composition, a method of directly adding the inorganic porous material fine particles in a state where the thermoplastic resin is heated and fluidized, or a method of mixing the thermoplastic resin with the photopolymerizable organic material Any method may be used in which the inorganic porous material fine particles are added during the kneading of the compound (b) first. However, it is preferable to avoid a method of directly mixing the inorganic porous material fine particles directly with the photopolymerizable organic substance (b) having a low molecular weight.
[0047]
That is, when the third method is used, the waste absorption performance of the inorganic porous body may be reduced. The reason for this is not clear, but the low-viscosity organic compound penetrates into the pores or voids in the inorganic porous material particles, and the polymerizable organic substance (b) in the pores is exposed in the exposure step when producing a printing original plate. It is presumed that this is due to hardening and filling of pores or voids.
[0048]
The photosensitive resin composition of the present invention is crosslinked by irradiation of light or electron beam to exhibit physical properties as a printing plate or the like. At that time, a polymerization initiator can be added. The polymerization initiator can be selected from those generally used. For example, initiators of radical polymerization, cationic polymerization, and anionic polymerization are exemplified in "Polymer Data Handbook-Basic Edition", edited by The Society of Polymer Science, Japan, published in Baifukan in 1986. I have. Further, performing crosslinking by photopolymerization using a photopolymerization initiator is useful as a method for producing a printing original plate with high productivity while maintaining the storage stability of the resin composition of the present invention. Known initiators can be used as well, 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-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1- ON, methyl phenylglyoxylate, benzophenone, benzyl In addition to photo-radical polymerization initiators such as diacetyl, diphenyl sulfide, eosin, thionine, anthraquinones, etc., photo-cationic polymerization of aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, etc., which generate acids by absorbing light And a polymerization initiator that absorbs light and generates a base. The addition amount of the polymerization initiator is preferably in the range of 0.01 to 10% by weight of the total amount of the resin (a) and the organic compound (b).
[0049]
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 depending on the use and purpose.
When the polymer component (a) is a liquid resin at 20 ° C., the photosensitive resin composition of the present invention is liquid, and from the viewpoint of processability into a sheet-like or cylindrical resin plate, particularly the liquid photosensitive resin composition The viscosity is preferably 10 Pa · s to 10 kPa · s at 20 ° C., more preferably 50 Pa · s to 5 kPa · s.
[0050]
The printing plate precursor capable of being laser-engraved according to the present invention is formed by photocrosslinking and curing a photosensitive material containing inorganic fine particles. Therefore, the polymerizable unsaturated group of the organic compound (b) or the polymerizable unsaturated group of the organic compound (b) reacts with the polymerizable unsaturated group of the organic component (b) to form a three-dimensional crosslinked structure. Insoluble in ketone, aromatic, ether, alcohol and halogen solvents. This reaction occurs between the organic compounds (b), between the polymer components (a), or between the polymer component (a) and the organic compound (b), and the polymerizable unsaturated group is consumed. In the case of crosslinking and curing using a photopolymerization initiator, since the photopolymerization initiator is decomposed by light, the crosslinked cured product is extracted with a solvent and separated by GC-MS method (mass separated by gas chromatography. Analytical method), LC-MS method (method for mass spectrometry of those separated by liquid chromatography), GPC-MS method (method for separating and mass spectrometric analysis by gel permeation chromatography), LC-NMR method (liquid chromatography) Analysis using a nuclear magnetic resonance spectrum) to identify unreacted photopolymerization initiators and decomposition products, as well as reducing agents used to reduce metals or their unreacted products can do. Furthermore, the unreacted polymer component (a), the unreacted organic compound (b), and the polymerizable unsaturated group in the solvent extract are obtained by using the GPC-MS method, the LC-MS method, and the GPC-NMR method. Can be identified from the analysis of the solvent extract. For the high molecular weight component that is insoluble in the solvent that has formed the three-dimensional crosslinked structure, by using the pyrolysis GC-MS method, the site generated by the reaction of the polymerizable unsaturated group as a component constituting the high molecular weight product is obtained. It is possible to verify that it exists. For example, the presence of a site where a polymerizable unsaturated group such as a methacrylate group, an acrylate group, or a vinyl group has reacted can be estimated from a mass spectrometry spectrum pattern. The pyrolysis GC-MS method is a method in which a sample is thermally decomposed, a generated gas component is separated by gas chromatography, and then mass spectrometry is performed. In the crosslinked cured product, decomposition products derived from the photopolymerization initiator and unreacted photopolymerization initiator are detected along with the unreacted polymerizable unsaturated group or the site obtained by the reaction of the polymerizable unsaturated group. Then, it can be concluded that the photosensitive resin composition is obtained by photocrosslinking and curing.
[0051]
Further, the amount of the inorganic porous material fine particles present in the crosslinked cured product can be obtained by heating the crosslinked cured product in the air, burning off the organic component, and measuring the weight of the residue. In addition, the presence of the inorganic porous material fine particles in the residue, morphological observation with a field emission type high resolution scanning electron microscope, particle size distribution with a laser scattering type particle size distribution measuring device, and nitrogen adsorption method It can be identified from measurements of pore volume, pore size distribution, and specific surface area.
[0052]
As a method for molding the resin composition of the present invention into a sheet shape or a cylindrical shape, an existing resin molding method can be used. For example, a casting method, a method in which a resin is extruded from a nozzle or a die with a machine such as a pump or an extruder, and the thickness is adjusted with a blade, or the thickness is adjusted by calendering with a roll, and the like can be exemplified. At this time, it is possible to perform molding while heating the resin within a range that does not deteriorate the performance of the resin. Further, a rolling process, a grinding process, or the like may be performed as necessary. 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 dimensional stability of the printing original plate. Therefore, it is necessary to select one having high dimensional stability. When evaluated using the coefficient of linear thermal expansion, the upper limit of the preferable material is 100 ppm / ° C. or less, more preferably 70 ppm / ° C. or less. Specific examples of the material 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, Examples thereof include a liquid crystal resin made of an aromatic polyester resin, a wholly aromatic polyamide resin, and an epoxy resin. Further, these resins can be laminated and used. For example, a sheet in which a 50 μm-thick polyethylene terephthalate layer is laminated on both sides of a 4.5 μm-thick wholly aromatic polyamide film may be used. In addition, a porous sheet, for example, a cloth formed by knitting fibers, a nonwoven fabric, a film having pores formed in a film, or the like can be used as the back film. When a porous sheet is used as the back film, the photosensitive resin composition is impregnated into the holes and then light-cured to obtain a high adhesiveness because the cured photosensitive resin layer and the back film are integrated. be able to. The fibers forming the cloth or nonwoven fabric include inorganic fibers such as glass fiber, alumina fiber, carbon fiber, alumina / silica fiber, boron fiber, high silicon fiber, potassium titanate fiber and sapphire fiber, and natural fibers such as cotton and hemp. Semi-synthetic fibers such as fibers, rayon, and acetate; and synthetic fibers such as nylon, polyester, acrylic, vinylon, polyvinyl chloride, polyolefin, polyurethane, polyimide, and aramid. Cellulose produced by bacteria is a highly crystalline nanofiber, and is a material from which a thin nonwoven fabric with high dimensional stability can be produced.
[0053]
Examples of the method for reducing the linear thermal expansion coefficient of the back film include a method of adding a filler, and a method of impregnating or coating a resin on a mesh cloth such as wholly aromatic polyamide, a glass cloth, or the like. As the filler, commonly used organic fine particles, inorganic fine particles of metal oxide or metal, and organic / inorganic composite fine particles can be used. In addition, porous fine particles, fine particles having a cavity therein, microcapsule particles, and layered compound particles into which a low molecular compound is intercalated can also be used. In particular, fine particles of metal oxides such as alumina, silica, titanium oxide, and zeolite, fine particles of latex made of a polystyrene / polybutadiene copolymer, and fine particles of natural organic materials such as highly crystalline cellulose are useful.
[0054]
By performing physical and chemical treatments 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, and an ultraviolet or vacuum ultraviolet irradiation method. Examples of the chemical treatment method include a strong acid / strong alkali treatment method, an oxidizing agent treatment method, and a coupling agent treatment method.
[0055]
The molded photosensitive resin composition is cross-linked by irradiation with light or an electron beam to form a printing original plate. In addition, crosslinking can be performed by irradiation with light or an electron beam while molding. Among them, the method of cross-linking 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, a xenon lamp, and the like, and curing can be performed by other known methods. The light source used for curing may be one type, but the curing property of the resin may be improved by curing using two or more types of light sources having different wavelengths. Therefore, two or more types of light sources may be used. No problem.
[0056]
Further, for the purpose of protecting the surface of the printing original plate, the photosensitive resin composition may be processed into a sheet or a cylindrical shape at the same time or afterwards, may be coated with a cover film.
The thickness of the 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.
[0057]
In the present invention, a cushion layer made of an elastomer can be formed below the layer to be laser-engraved. Generally, the thickness of the layer to be laser-engraved is 0.1 to several mm, and 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, it is appropriately deformed, so that print quality can be ensured. In addition, if it is 70 degrees or less, it can serve as a cushion layer. A more preferable range of Shore A hardness is 30 to 60 degrees.
[0058]
The cushion layer is not particularly limited, and may be any material having rubber elasticity, such as a thermoplastic elastomer, a photo-curable elastomer, and a thermo-curable elastomer. It may be a porous elastomer layer having nanometer-level fine pores. In particular, from the viewpoint of workability into a sheet-like or cylindrical printing plate, it is simple and preferable to use a liquid photosensitive resin composition which is cured by light and to use a material which becomes an elastomer after curing.
[0059]
Specific examples of the thermoplastic elastomer used for the cushion layer include styrene-based thermoplastic elastomers such as SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), and SEBS (polystyrene-polyethylene / polybutylene-polystyrene). And olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, amide-based thermoplastic elastomers, silicone-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers.
[0060]
Examples of the photocurable elastomer include a mixture of the thermoplastic elastomer with a photopolymerizable monomer, a plasticizer and a photopolymerization initiator, and a liquid composition obtained by mixing a plastomer resin with a photopolymerizable monomer, a photopolymerization initiator, and the like. Can be mentioned. In the present invention, unlike the design concept of a 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 the entire surface by exposure, Since it is only necessary to ensure a certain level of mechanical strength, the degree of freedom in selecting materials is extremely high.
[0061]
Further, non-sulfur crosslinked rubber such as sulfur crosslinked rubber, organic peroxide, phenol resin precondensate, quinone dioxime, metal oxide, and thiourea can also be used. Further, an elastomer obtained by three-dimensionally cross-linking a telechelic liquid rubber using a curing agent that reacts can be used.
In the case of multilayering in the present invention, the position of the back film is below the cushion layer, that is, the lowermost part of the printing original plate, or the position between the laser engravable photosensitive resin layer and the cushion layer, that is, the printing original plate. In the center, any position is acceptable.
[0062]
Further, by forming a modified layer on the surface of the laser engraving printing plate of the present invention, it is possible to reduce tackiness on the printing plate surface and to improve ink wettability. 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.
[0063]
A widely used silane coupling agent is a compound having a functional group having high reactivity with a surface hydroxyl group of a substrate in a molecule, and such a functional group is, for example, a trimethoxysilyl group or a triethoxysilyl group. Group, trichlorosilyl group, diethoxysilyl group, dimethoxysilyl group, dimonochlorosilyl group, monoethoxysilyl group, monomethoxysilyl group, monochlorosilyl group. In addition, at least one or more of these functional groups are present in the molecule, and are immobilized on the surface of the substrate by reacting with hydroxyl groups on the surface of the substrate. Further, the compounds constituting the silane coupling agent of the present invention are selected from acryloyl groups, methacryloyl groups, active hydrogen-containing amino groups, epoxy groups, vinyl groups, perfluoroalkyl groups, and mercapto groups as reactive functional groups in the molecule. A compound having at least one functional group or a compound having a long-chain alkyl group can be used.
[0064]
Examples of the titanium coupling agent 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, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearyl diacryl titanate Over DOO, isopropyl tri (dioctyl sulfate) titanate, isopropyl tricumylphenyl titanate, tetraisopropyl bis (dioctyl phosphite) may include compounds such as titanates.
[0065]
When the coupling agent molecule immobilized on the surface particularly has a polymerizable reactive group, a stronger film can be formed by irradiating light, heat, or an electron beam to crosslink after immobilization on the surface. .
In the present invention, the above-mentioned coupling agent is adjusted by diluting it with a water-alcohol or acetic acid-water-alcohol mixture as required. The concentration of the coupling agent in the treatment liquid is preferably 0.05 to 10.0% by weight.
[0066]
The method for treating a coupling agent in the present invention will be described. The treatment liquid containing the above-mentioned coupling agent is used by applying it to the printing original plate or the printing plate surface after laser engraving. The method of applying the coupling agent treatment liquid is not particularly limited, and for example, a dipping method, a spray method, a roll coating method, a brush coating method, or the like can be applied. The coating temperature and the coating time are not particularly limited, but are preferably 5 to 60 ° C., and the processing time is preferably 0.1 to 60 seconds. Further, the drying of the treatment liquid layer on the surface of the resin plate is preferably performed under heating, and the heating temperature is preferably 50 to 150 ° C.
[0067]
Before treating the printing plate surface with a coupling agent, a method of irradiating light in a vacuum ultraviolet region having a wavelength of 200 nm or less, such as a xenon excimer lamp, or exposing the printing plate surface to a hydroxyl group by exposing to a high energy atmosphere such as plasma. And the coupling agent can be immobilized at high density.
When the layer containing the inorganic porous material particles is exposed on the surface of the printing plate, the layer is treated under a high-energy atmosphere such as plasma, and the organic material layer on the surface is slightly removed by etching to form a minute surface on the printing plate. Irregularities can be formed. This treatment can also be expected to reduce the tack on the surface of the printing plate and to improve the ink wettability by making the inorganic porous material particles exposed on the surface easily absorb the ink.
[0068]
In laser engraving, an image to be formed is converted into digital data by using a computer to operate a laser device to create a relief image on an original. As the laser used for laser engraving, any laser may be used as long as it includes a wavelength at which the original plate has an absorption.However, in order to perform engraving at a high speed, a laser having a high output is desirable. An infrared ray or an infrared ray emitting solid laser such as a YAG laser or a semiconductor laser is one of the preferable ones. In addition, an ultraviolet laser having an oscillation wavelength in an ultraviolet region, for example, an excimer laser, a YAG laser whose wavelength has been converted to a third or fourth harmonic, a copper vapor laser, or the like can be subjected to abrasion processing for cutting the bonds of organic molecules. Suitable for fine processing. The laser may be used for continuous irradiation or pulse irradiation. In general, the resin has an absorption around 10 μm of the carbon dioxide laser. Therefore, it is not necessary to add a component which particularly assists the absorption of the laser beam. However, the wavelength of the YAG laser is around 1.06 μm. There are not many that have. In that case, it is necessary to add a dye and a pigment, which are components that assist the absorption. Examples of such dyes include poly (substituted) phthalocyanine compounds and metal-containing phthalocyanine compounds; cyanine compounds; squarylium dyes; chalcogenopyrroliarylidene dyes; chloronium dyes; metal thiolate dyes; Indolidine dye; bis (aminoaryl) polymethine dye; merocyanine dye; and quinoid dye. Examples of pigments include carbon black, graphite, copper chromite, chromium oxide, cobalt chrome aluminate, dark inorganic pigments such as iron oxide, iron, aluminum, copper, metal powders such as zinc, and metal such as Si, Examples thereof include those doped with Mg, P, Co, Ni, Y, and the like. These dyes and pigments may be used alone, may be used in combination of two or more, and may be combined in any form such as a multilayer structure. However, in the case where the photosensitive resin composition is cured using ultraviolet light or visible light, in order to cure the inside of the printing original plate, it is preferable to reduce the amount of a dye or pigment that absorbs light in the light region to be used. Although the curing properties are greatly affected by the type of photopolymerization initiator to be added, the amount of the dye or pigment added is preferably 5 wt% or less, more preferably 1 wt% or less, and still more preferably 0.5 wt% or less. Is desirable.
[0069]
Laser engraving is performed under an oxygen-containing gas, generally in the presence of air or in an air stream, but can also be performed under carbon dioxide gas or nitrogen gas. After engraving, powdery or liquid substances that are slightly generated on the relief printing plate surface are washed by a suitable method, for example, a method of washing with water or the like containing a solvent or a surfactant, or a method of irradiating an aqueous cleaning agent with a high-pressure spray or the like. Alternatively, it may be removed using a method of irradiating high pressure steam.
The original plate of the present invention is a relief image for a printing plate, a stamp / seal, a design roll for embossing, a resistor used for making an electronic component, a relief image for patterning a conductive paste, a relief image for a ceramic product, It can be applied and used for various applications such as relief images for displays such as advertisements and display boards, prototypes and matrices of various molded products.
[0070]
Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto.
In Examples and Comparative Examples, laser engraving was performed using a trademark “TYP STAMPLAS SN 09” manufactured by BAASEL. The engraving pattern was a halftone dot, a line drawing by a 500 μm-wide convex line, and a 500 μm-wide white line. Was created and implemented. The engraving depth was 0.55 mm.
[0071]
After laser engraving, the residue on the relief printing plate was wiped off using a nonwoven fabric (trade name “BEMCOT M-3” manufactured by Asahi Kasei Corporation) impregnated with ethanol or acetone. The weight of each of the printing plate before laser engraving, the printing plate immediately after laser engraving, and the relief printing plate after wiping were measured, and the residue ratio of engraving at the time of engraving was determined by equation (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)
[0072]
The tack measurement of the relief printing plate surface after wiping was performed using a tack tester manufactured by Toyo Seiki Seisaku-sho, Ltd. At 20 ° C., at 20 ° C., a portion of a 13 mm wide aluminum ring having a radius of 50 mm and a width of 13 mm was brought into contact with a smooth portion of a sample piece, a load of 0.5 kg was applied to the aluminum ring, and the aluminum ring was left for 4 seconds. The aluminum wheel is pulled up at a constant speed of 30 mm, and the resistance force when the aluminum wheel separates from the sample is read by a push-pull gauge. The greater this value, the greater the stickiness.
Further, among the engraved portions, the shape of a halftone dot portion having an area ratio of about 10% was observed with an electron microscope at 80 lpi (Lines per inch).
[0073]
The specific surface area and pore distribution of the fine particles were measured using Autosoap 3MP (trade name, manufactured by Cantachrome Co., USA) in a liquid nitrogen temperature atmosphere by adsorbing nitrogen gas. Specifically, the specific surface area was calculated based on the BET equation. The pore volume and the average pore diameter were calculated based on a pore distribution analysis method called a BJH (Brrett-Joyner-Halenda) method, assuming a cylindrical model from an adsorption isotherm at the time of desorption of nitrogen.
The X-ray fluorescence analyzer used for elemental analysis of the printing plate surface is PW2400 (trademark) manufactured by Philips, and uses a Rh bulb as an excitation source. The analysis diameter is 10 mmφ.
[0074]
[Production Example 1]
In a 1 L separable flask equipped with a thermometer, a stirrer, and a reflux condenser, 447.24 g of trademark "PCDL L4672" (number average molecular weight 1990, OH value 56.4), a polycarbonate diol manufactured by Asahi Kasei Corporation, and tolylene diisocyanate After adding 30.83 g and reacting at 80 ° C. for about 3 hours while heating, 7.42 g of 2-methacryloyloxyisocyanate was added and reacted for about 3 hours, so that the terminal was a methacryl group (intramolecular polymerization). Resin (A) having a number average molecular weight of about 10,000 (wherein one unsaturated unsaturated group per molecule on average) was produced. This resin was syrupy at 20 ° C., flowed when an external force was applied, and did not recover its original shape even when the external force was removed.
[0075]
Embodiments 1 to 3
Using the resin (a) obtained in the above-mentioned production example, a styrene butadiene copolymer manufactured by Asahi Kasei Corporation, and a trademark “Taphrene A” (hereinafter abbreviated as SBS), a polymerizable monomer and an inorganic porous "Silosphere C-1504" (hereinafter abbreviated as C-1504, number average particle diameter 4.5 μm, specific surface area 520 m) which is porous silica manufactured by Fuji Silysia Chemical Ltd.²/ G, average pore diameter 12 nm, pore volume 1.5 ml / g, loss on ignition 2.5 wt%, oil absorption 290 ml / 100 g), trademark “thyricia 450” (hereinafter abbreviated as CH-450, number average particle diameter 8.) 0 μm, specific surface area 300 m²/ G, average pore diameter 17 nm, pore volume 1.25 ml / g, loss on ignition 5.0 wt%, oil absorption 200 ml / 100 g), a photopolymerization initiator, and other additives to prepare a resin composition. The porosity of the porous finely powdered silica used was determined to be 2 g / cm in density.³Were calculated, and 780 was obtained for Silosphere C-1504 and 800 was obtained for Thylsia 450. The sphericity of the added porous spherical silica, Silosphere C-1504, was observed using a scanning electron microscope, and almost all particles were 0.9 or more. Sylysia 450 was porous silica but not spherical silica. The prepared mixture was formed into a sheet having a thickness of 2.8 mm on a PET film, and the surface thereof was covered with a PET cover film having a thickness of 15 μm. Then, an “ALF type 213E” (trademark) exposing machine manufactured by Asahi Kasei Corporation was used. Relief surface 2,000 mJ / cm under vacuum conditions², Back surface 1000mJ / cm²And a resin plate was prepared.
[0076]
The number of times of scrap removal after engraving in Table 2 is the number of times of wiping processing necessary to remove viscous liquid residue generated after engraving, and a large number of times means a large amount of liquid residue. I do. Regarding the tack on the relief after wiping, in any of Examples 1 to 3, in the printing plate after laser engraving, the tack on the surface of the non-engraved portion was 100 N / m or less, and before the engraving, that is, of the photosensitive resin composition. The surface tack value of the photocured product was reduced as compared with 150 to 200 N / m. Further, the tack on the surface of the engraved portion was less than 50 N / m.
[0077]
Table 3 shows the results of elemental analysis by the fluorescent X-ray method. The characteristic X-ray intensity of silicon is Ie and Ie₀, The characteristic X-ray intensity of carbon is Ic and Ic₀It is. The characteristic X-ray intensity of the laser engraved part is Ie and Ic, and the characteristic X-ray intensity of the unengraved part is Ie.₀And Ic₀It is. In addition to the engraving of the halftone dot pattern described above, a width of 20 mm and a length of 50 mm for fluorescent X-ray measurement and two engraving depths of 0.3 mm and 1.4 mm were set. Laser engraving was performed on the engraving originals of Nos. 1 to 3. After engraving, the residue was wiped off three times to obtain a sample for X-ray fluorescence analysis.
When the surface of the laser engraved portion was observed using a scanning electron microscope, fine particles exposed on the surface were confirmed. An electron micrograph of the surface of the engraved part of Example 1 is shown in FIG.
[0078]
As shown in Table 2, in Examples 1 to 3, the shape of the halftone dot portion was conical and good, but in comparison with Example 1, Example 3 showed removal of engraving residue when observed with an electron microscope. Was slightly inferior. FIG. 2 shows the shape of the halftone dot observed by the scanning electron microscope of Example 1, and FIG. 3 shows the shape of the halftone dot of Example 3. Further, when a shape evaluation was performed on a dot pattern having a larger size using a scanning electron microscope, a pattern having a smooth surface was formed in Example 1 as shown in FIG. As shown in (3), in Example 3, the surface was slightly uneven.
[0079]
Further, the inorganic porous material in the printing plate was removed by removing the resin component at 500 ° C. in air. Observation of the removed fine particles with an ultra-high-resolution scanning electron microscope revealed fine pores. The specific surface area, pore volume, and average pore diameter of the fine particles were measured using "Auto Soap 3MP" (trademark) manufactured by Cantachrome Co. in the United States under a liquid nitrogen temperature atmosphere while adsorbing nitrogen gas. As a result, all the physical property values were within ± 10% of the value measured before the addition, and it was confirmed that the particles were inorganic porous fine particles.
In addition, when the abrasion resistance of the printing original plate was evaluated, it was found that the one using spherical silica, Silossphere C-1504, had a smaller amount of abrasion and was superior to the one using Cysyria 450.
The number average molecular weight of the thermoplastic elastomer SBS used in Example 3 of the present invention was 77,000 as measured by GPC and determined based on a polystyrene standard.
[0080]
Among the double bond-containing organic compounds used in Examples of the present invention, alicyclic and aromatic derivatives are BZMA and CHMA.
The softening temperature of SBS used in Examples of the present invention was 130 ° C. The softening temperature was measured using a viscoelasticity measuring device manufactured by Rheometrics Scientific F.E. and a rotary rheometer. The heating was started from room temperature at a measurement frequency of 10 rad / sec and a heating rate of 10 ° C./min, and the temperature at which the slime ratio was greatly reduced first was determined as the softening point.
[0081]
Embodiment 4
Asahi Kasei Co., Ltd., trade name "APR, F320" Photocured in the same manner as in Example 1 except that the liquid photosensitive resin composition was formed into a sheet having a thickness of 2.7 mm to form a cushion layer of the printing original plate. . On the cushion layer, the liquid photosensitive resin composition used in Example 1 was applied to a thickness of 0.8 mm, and then subjected to an exposing step to prepare a printing original plate. The Shore A hardness of the cushion layer was 47 degrees.
The residue ratio after engraving with a carbon dioxide laser is 5.7 wt%, the number of times of scrap removal after engraving is 3 or less, the tack on the relief after wiping is 60 N / m, and the shape of the halftone dot portion is conical and good. there were.
[0082]
[Comparative Example 1]
A printing original plate was prepared in the same manner as in Example 1 except that sodium calcium aluminosilicate (trade name "Silton JC50" manufactured by Mizusawa Chemical Co., Ltd.) was used as a nonporous material instead of the inorganic porous material fine particles. The non-porous material used had an average particle size of 5.0 μm, a pore volume of 0.02 ml / g, and a specific surface area of 6.7 m.²/ G, oil absorption 45 ml / 100 g. The porosity is 2 g / cm³Was 11.
After engraving with a carbon dioxide laser, a large amount of viscous liquid scum was generated, and the number of times of scum wiping was required to exceed 10 times. The shape of the halftone dot portion was conical and good, but the tack on the relief after wiping was 150 N / m.
The depth of engraving in the engraved portion having a width of 20 mm and a length of 50 mm, which was laser-engraved for X-ray fluorescence analysis, was 1.4 mm. After wiping the residue three times as in the example, analysis was performed by the fluorescent X-ray method. (Ie / Ic) / (Ie₀/ Ic₀) Was less than 1.5. The stickiness of the surface of the engraved part of this sample was large.
In addition, when the surface of the engraved portion was observed using a scanning electron microscope, nothing could be confirmed as fine particles.
[0083]
[Table 1]

[0084]
[Table 2]

[0085]
[Table 3]

[0086]
【The invention's effect】
According to the present invention, the generation of scum when producing a relief image by direct laser engraving is suppressed, and not only the scum can be easily removed, but also the flexo printing which has an excellent engraved relief shape and a small tack on the printing surface. Version can be provided.
[Brief description of the drawings]
FIG. 1 is a scanning electron micrograph of the surface of an engraved part in Example 1.
FIG. 2 is an electron micrograph showing a pattern shape of a halftone dot portion in Example 1.
FIG. 3 is an electron micrograph showing a pattern shape of a halftone dot portion in Example 3.
FIG. 4 is an electron micrograph showing the dot pattern shape of Example 1.
FIG. 5 is an electron micrograph showing the dot pattern shape of Example 3.

Claims (7)

A printing plate made of a photo-cured product of a photosensitive resin composition having a concavo-convex pattern formed by irradiating a laser beam, with the inorganic porous material fine particles being exposed on the surface of the engraved portion removed by the laser beam irradiation. When present, when the surface is subjected to elemental analysis using the fluorescent X-ray method, the characteristic X-ray intensity Ie of the specific element and the characteristic X-ray intensity of carbon in the inorganic porous fine particles detected from the surface of the engraved portion (Ie / Ic) / (Ie ₀ ), which is the ratio of the intensity ratio between Ic and the characteristic X-ray intensity Ie _{0 of the} specific element detected from the surface of the non-engraved portion and the characteristic X-ray intensity Ic _{0 of} carbon. / Ic ₀ ) having a value of 1.5 or more. The inorganic porous fine particles contained in the cured photosensitive resin have a specific surface area of 10 m ² / g to 1500 m ² / g, an average pore diameter of 1 nm to 1000 nm, and a pore volume of 0.1 ml / g to 10 ml / g. 2. The printing plate according to claim 1, wherein the oil engraving amount is 10 ml / 100 g or more and 2000 ml / 100 g or less. The laser according to claim 1 or 2, wherein the photosensitive resin composition contains a resin (a) having a number average molecular weight of 1,000 to 500,000 and an organic compound (b) having a polymerizable unsaturated group having a number average molecular weight of less than 1,000. Engraving printing plate. The laser engraving printing plate according to claim 3, wherein 20% by weight or more of the total amount of the organic compound (b) is at least one kind of an alicyclic or aromatic derivative. The number average particle diameter of the inorganic porous material fine particles 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. The printing plate for laser engraving according to 3 or 4. A multilayer laser engraving printing plate having at least one elastomer layer having a constant thickness of not less than 20 degrees and not more than 70 degrees below the printing plate according to any one of claims 1 to 5. The multilayer laser engraving printing plate according to claim 6, wherein the elastomer layer is formed by curing the liquid photosensitive resin composition at 20 ° C.

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