JP2008168505A - Cushion material for printing - Google Patents

Abstract

Provided are a cushion for printing and a cushion layer for a printing plate that reduce density unevenness of halftone dots caused by vibration.
A cushioning material for printing having at least one organic fine particle or inorganic fine particle having an average diameter of 0.1 μm or more and 100 μm or less. If the printing cushion contains fine particles, when vibration is given to the printing cushion from a printing press or printing plate, the fine particles in the cushion move and vibrate, so that the external vibration is heated. It is presumed that the density unevenness of the halftone dots has been reduced because the vibration is attenuated by converting to.
[Selection] Figure 1

Description

  The present invention relates to a material for manufacturing a cushion for printing and a cushion layer of a printing plate that are used by being disposed under a printing plate during printing.

In recent years, flexographic printing has been widely used in soft packaging such as paper and film. In general, the quality of printing such as flexographic printing is solid quality, that is, high solid density, high solid concealment, and halftone dot quality, that is, dots and lines with less weight, white spots with less embedding, etc. It is determined by balance.
By the way, when the deformation of the printing plate becomes large, it becomes difficult to reproduce a desired image on the printing medium. Therefore, in order to reduce the excessive deformation of the printing plate caused by the vibration of the printing machine and maintain the printing quality, A cushion is often provided under the printing plate.
As a cushion material for reducing excessive deformation of the printing plate, sheet-like polyethylene, thermosetting polyurethane, and the like are generally used and are classified into several types depending on the purpose of printing quality. In general, these cushion materials have poor dot quality when priority is given to solid quality, and conversely, when priority is given to dot quality, the quality of solids tends to be poor.

  Patent Document 1 describes a flexographic mounting tape made of a laminate of polyester and polyethylene foam. In this method, the plate surface has a lower resonance frequency compared to the kinetic frequency of the printing press, and a good repulsive force or an improved mounting tape that allows for higher printing speeds and improved printing characteristics. A material having elasticity is provided. However, even if this tape is used, both solid quality and halftone dot quality cannot be achieved.

  Patent Document 2 has a description that a cylindrical multilayer cushion layer suppresses a striped pattern of a printed matter due to vibration during printing. However, even this cushion layer cannot achieve both solid quality and halftone dot quality. Moreover, since it is necessary to prepare a cylindrical multilayer cushion layer having a different size for each print circumference, the burden on the printing company is large.

  Patent Document 3 discloses that the thermal expansion is performed by heating the resin in a process of mixing a thermally expandable capsule into a resin mainly composed of a thermoplastic elastomer and forming the sheet into a sheet shape using an extrusion molding technique. Describes a method of thermally expanding a functional capsule to form a cushion layer. However, even this cushion layer cannot achieve both solid quality and halftone dot quality.

As described above, in printing cushions whose main purpose is to reduce excessive deformation of the printing plate, the compatibility between solid quality and halftone dot quality has not been achieved so far.
JP 61-291191 A International Publication No. 2004/022340 Pamphlet Special table 2003-519036 gazette

  An object of the present invention is to provide a cushion for printing and a cushion layer of a printing plate that can achieve both solid quality and halftone dot quality.

As a result of intensive studies to solve the above problems, the present inventors have found that the problem can be solved by adding fine particles having an average diameter of 1 μm to 100 μm to the cushioning material for printing. It came to make.
That is, the present invention is a cushioning material for printing containing fine particles having an average diameter of 1 μm or more and 100 μm or less.

Since the primary role of the cushion for printing is to relieve the impact, materials that are easily compressed are usually used. In general, printing cushions that are more easily compressed have better dot quality, i.e., dot print reproducibility, but solid quality, i.e., solid concealment rate and solid density, tend to be inferior. However, if a printing cushion that is difficult to be compressed is used to improve the solid quality, the dot quality tends to be inferior.
Therefore, the present inventors investigated the cause of poor dot quality when using a cushion for printing that is difficult to compress. When the cushion for printing that is difficult to compress is used, it is caused by vibration generated from a printing press or the like. It has been found that the density unevenness of the halftone dots is not sufficiently improved.

  Furthermore, as a result of intensive studies on a method for reducing density unevenness of halftone dots caused by vibrations, the present inventors have found that vibrations occur when at least one kind of fine particles having an average diameter of 0.1 μm or more and 100 μm or less are added to a printing cushion. It has been found that the density unevenness of the halftone dots caused by the above is reduced and the printing quality is improved.

  The mechanism by which the density unevenness of the halftone dots is reduced by adding fine particles to the printing cushion is not clear. However, if the printing cushion contains fine particles, when vibration is given to the printing cushion from a printing press or printing plate, the fine particles in the cushion move and vibrate from the outside. It is presumed that the density unevenness of the halftone dots is reduced because the vibration is converted into heat and the vibration is attenuated.

  By using a printing cushion or a printing cushion layer manufactured from the printing cushion material of the present invention, the density unevenness of halftone dots generated by vibration generated during printing is reduced, and the halftone dot quality and the solid quality are satisfied at the same time. High print quality can be achieved.

Hereinafter, the present invention will be specifically described.
The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.

The cushion material for printing of the present invention contains fine particles having an average diameter of 0.1 μm or more and 100 μm or less.
In the present invention, the average diameter of the fine particles is 0.1 μm or more and 100 μm or less.
When the average diameter of the fine particles exceeds 100 μm, the compressibility is unevenly distributed on the printing plate, which may affect fine images. On the other hand, when the size is less than 0.1 μm, the handleability is lowered and the weighing becomes difficult. A preferred range is from 0.2 μm to 90 μm, and a more preferred range is from 0.3 μm to 80 μm. If it is this range, there will be little influence on the fine pattern of a printing plate, and it will be excellent also in handleability.
Furthermore, from the viewpoint of eliminating density unevenness, the average particle diameter of the fine particles is preferably 0.5 μm or more and 80 μm or less, more preferably 1.0 μm or more and 80 μm or less, and further preferably 1.5 μm or more and 80 μm or less.

  Here, the average particle diameter refers to the average value of the major axis values. As a method for measuring the average diameter, for example, the magnification is adjusted so that at least about 50 fine particles enter the field of view of the microscope, and the long diameter of the fine particles is measured. Although it is preferable to use a microscope having a length measuring function, the dimensions may be measured based on a photograph taken using a camera.

In the present invention, the material of the fine particles is not limited, and may be fine particles formed of either an organic compound or an inorganic compound.
The fine particles formed from the organic compound are not particularly limited, and preferable examples include rubber powder, halogenated resin fine particles, crosslinked acrylic acid fine particles, crosslinked acrylic acid porous fine particles, and crosslinked polystyrene fine particles. . Specifically, silicone composite powder, silicone rubber powder, silicone resin powder, soft fluororesin, soft vinyl chloride, polytetrafluoroethylene, fluororubber, crosslinked polyacrylate, crosslinked polymethyl methacrylate, crosslinked polymethacrylate Examples thereof include fine particles such as butyl acid. These particles may be surface-treated in order to improve the affinity with the binder resin. Among these, silicone rubber powder and fine particles made of a soft fluororesin are particularly preferable.
Fine particles formed from organic compounds are organic having fine cores containing fine bubbles, porous fine particles, a core portion with a soft composition synthesized by applying a core / shell emulsion polymerization technique, and a shell portion with a hard composition. -Inorganic hybrid multilayer structure fine particles are included, but hollow organic fine particles are not included in the fine particles in the present invention because they are poor in vibration absorption capability.

The fine particles formed from the inorganic compound are not particularly limited, and examples thereof include particles containing an alkaline earth element, silicon, aluminum and the like. As specific examples, glass micro hollow bodies; colloidal calcium carbonate, light calcium carbonate, ultrafine calcium carbonate, surface-treated ultrafine calcium carbonate, zeolite, talc, kaolin, barium sulfate, mica, glass fiber, glass beads, clay, Examples thereof include particles made of cryolite, magnesium hydroxide, and the like. These particles may be surface-treated in order to improve the affinity with the binder resin. Among these, fine particles made of a calcium carbonate-based material are particularly preferable.
In the present invention, one or more kinds of these fine particles can be contained.

The specific gravity of the fine particles contained in the printing cushion material of the present invention is preferably 0.1 g / cm ³ or more and 3.0 g / cm ³ or less. Preferably 0.3 g / cm ³ or more 2.5 g / cm ^3, more preferably not more than 0.5 g / cm ³ or more 2.0 g / cm ^3. Within this range, when mixed with the cushion material, the fine particles are less likely to be precipitated and unevenly distributed, and are less likely to be scattered like dust during handling.
Moreover, since the width | variety of the quantity added to the cushion material for printing will become wide if it is the specific gravity of the said range, the vibration during printing can be damped more effectively.
Further, the content of the fine particles in the printing cushion material is not particularly limited as long as it does not impair the compressibility of the printing cushion material, but is 1 to 30% by weight with respect to the printing cushion material. It is preferably 2 to 25% by weight, more preferably 3 to 20% by weight. If the content is within this range, density unevenness can be reduced without impairing the compressibility of the printing cushion material.

The loss tangent (tan δ) (loss elastic modulus G ″ / storage elastic modulus G ′) at 20 ° C. and 400 Hz of the printing cushion material is preferably 0.2 or more and 0.8 or less. Since the influence of vibration is likely to occur at a relatively low frequency in the vibration region of the printing plate, attention was paid to the loss tangent at 400 Hz.
Loss tangent (tan δ) at 400 Hz can be adjusted by adjusting the monomer ratio and the amount of fine particles, for example, when the printing cushion material is a photocured product of a photosensitive resin composition to be described later. It is estimated that it is possible to reach around 0.8 while maintaining the range.

  If the loss tangent (tan δ) at 20 ° C. and 400 Hz of the printing cushion material is in the above range, the printing cushion manufactured thereby will not be permanently deformed and can absorb sufficient impact, so printing is in progress. Suitable for absorbing vibration. The loss tangent (tan δ) at 20 ° C. and 400 Hz of the printing cushion material is more preferably 0.21 or more and 0.80 or less, and further preferably 0.22 or more and 0.80 or less.

In the present invention, the storage elastic modulus and loss elastic modulus at 20 ° C. and 400 Hz can be measured by the following method, for example.
Set the sample to the shear geometry of the dynamic viscoelasticity measuring device. For example, the effective measurement thickness is 1 mm, the effective measurement diameter is 9 mm, the strain amplitude is 0.5%, and the measurement frequency is sine wave from 0.1 Hz to 20 Hz. Measure the storage elastic modulus and loss elastic modulus when changed in the range of -10 ° C every measurement temperature from 30 ° C to -20 ° C, according to the application of dynamic annual elasticity measuring device, To create a master curve with a reference temperature of 20 ° C., and read the storage elastic modulus and loss elastic modulus at 400 Hz from the obtained master curve.

The printing cushion material of the present invention is preferably hard to be compressed. Specifically, the compressive stress at a compression rate of 20% measured at 23 ° C. is preferably 2.0 × 10 ⁵ Pa or more, more preferably 2.5 × 10 ⁵ Pa or more, and further preferably 3 0.0 × 10 ⁵ Pa or more.
Here, the compressive stress at a compression rate of 20% is the repulsion exhibited by the sample when the sample having a thickness of 2 mm and a size of 20 mm × 20 mm is vertically compressed until the compression rate represented by the following equation reaches 20%. It refers to stress (Pa).
Compression rate (%) = {(thickness before compression−thickness after compression) / (thickness before compression)} × 100
Although there is no limitation in the measuring method of a compression rate and a repulsive stress, it can measure using a compression characteristic evaluation apparatus (The Shimadzu Corporation make, a trademark "Autograph, AGS-J") according to JISK7181, for example. Specifically, a square sample having a thickness of 2 mm and a size of 20 mm × 20 mm is prepared, and a double-sided tape (trademark “ST-416” manufactured by 3M Co., Ltd.) is used at a location estimated to be the central portion of the load cell of the compression property evaluation apparatus. ) Is used to fix the lower surface, and the substrate is compressed vertically at a compression speed of 1.0 mm / min, and the rebound stress is measured when the compression rate reaches 20%.

The printing cushion material of the present invention preferably contains a binder. The binder is not limited, but is preferably a resin. In particular, in order to form a cushioning material for printing that is difficult to be compressed for improving the solid quality of the printed matter, the binder resin is a photosensitive resin composition. A photocured product is preferred.
The method of curing the photosensitive resin composition using light, for example, cross-linking curing, does not include a heating step, etc., and therefore has the advantage that the curing reaction can be completed in a short time and the mechanical properties of the cured product can be ensured. It is suitable. Examples of the light source used for curing include metal halide lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, ultraviolet fluorescent lamps, carbon arc lamps, xenon lamps, zirconium lamps, sunlight, and the like, and curing can be performed by other known methods. Moreover, you may irradiate the light of a several kind of light source. In addition, in this invention, a photocured material means what was obtained by photocuring.
In particular, in the present invention, it is preferable to use a photocured product of the photosensitive resin composition (A) containing the resin (a), the organic compound (b), and the photopolymerization initiator (c) as the binder.

It is preferable to use a resin (a) having a carbonate bond in the molecule because the loss tangent (tan δ) at 400 Hz of the printing cushion material can be easily adjusted to 0.20 or more and 0.8 or less.
Further, as the resin (a), at least one type of bond selected from an ester bond, a urethane bond, and an amide bond and / or a urea skeleton and / or an aliphatic saturated hydrocarbon chain, an aliphatic unsaturated hydrocarbon is further included in the molecule. It is preferable to have at least one molecular chain selected from chains.
In particular, the resin (a) has a carbonate bond, an ester bond in the molecule, and / or at least one molecular chain selected from an aliphatic saturated hydrocarbon chain and an aliphatic unsaturated hydrocarbon chain, In addition, it is preferable to use a polymer compound having at least one kind of bond selected from a urethane bond and an amide bond or a urea skeleton.
When such a polymer compound is included, resistance to ink containing an ester solvent used in flexographic printing and ink containing a hydrocarbon solvent used in offset printing can be secured.

In order to introduce a carbonate bond into the molecular chain of the resin (a) used in the present invention, as a monomer component used in producing the resin (a), for example, 4,6-polyalkylene carbonate diol, 8 , 9-polyalkylene carbonate diol, aliphatic polycarbonate diol such as 5,6-polyalkylene carbonate diol can be used. Moreover, you may use the aliphatic polycarbonate diol which has an aromatic type molecular structure in a molecule | numerator.
In this case, the terminal hydroxyl group has tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, trimethylhexamethylene diisocyanate, p-phenylene diisocyanate, cyclohexylene. A diisocyanate compound such as diisocyanate, lysine diisocyanate, or triphenylmethane diisocyanate, or a triisocyanate compound may be subjected to a condensation reaction to further increase the molecular weight and introduce a urethane bond.
Further, a terminal hydroxyl group or isocyanate group can be used for introducing a polymerizable unsaturated group.

In order to introduce an ester bond into the molecular chain of the resin (a) used in the present invention, as monomer components used in producing the resin (a), adipic acid, phthalic acid, malonic acid, succinic acid, Dicarboxylic acid compounds such as itaconic acid, oxalic acid, glutaric acid, pimelic acid, speric acid, azelanic acid, sebacic acid, fumaric acid, isophthalic acid, terephthalic acid, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, Trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10- Decanediol, piconal, cyclopentanediol, cyclohexa Using a compound having two or more hydroxyl groups in the molecule of the diol, and these polyesters are obtained by condensation reaction; can be introduced polyesters of polycaprolactone.
In this case, a urethane bond can be introduced by further increasing the molecular weight by subjecting the above-mentioned diisocyanate compound to a condensation reaction with a terminal hydroxyl group or carboxyl group.
Further, a terminal hydroxyl group or carboxyl group can be used for introducing a polymerizable unsaturated group.

  In order to introduce the urea skeleton into the molecular chain of the resin (a) used in the present invention, urea and formaldehyde are used as monomer components used in producing the resin (a), and these are subjected to a condensation reaction. Can do. A compound having a functional group that reacts with an amino group formed at the terminal can be further condensed.

  In order to introduce an amide bond into the molecular chain of the resin (a) used in the present invention, a diamine compound and a dicarboxylic acid compound are used as monomer components used in the production of the resin (a), and these are condensed. Can be reacted. Examples of diamine compounds include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, and the like. Aliphatic diamine compounds; aromatic diamine compounds such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine and the like can be mentioned. Further, as dicarboxylic acid compounds, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, spellic acid, azelaic acid, sebacic acid and other aliphatic saturated dicarboxylic acid compounds; maleic acid, fumaric acid, itaconic acid And aliphatic unsaturated dicarboxylic acid compounds such as phthalic acid, isophthalic acid and terephthalic acid.

  Examples of the aliphatic hydrocarbon chain or aliphatic unsaturated hydrocarbon chain introduced into the molecular chain of the resin (a) used in the present invention include polybutadiene, polyisoprene, hydrogenated polybutadiene, partially hydrogenated polybutadiene, hydrogenated Examples of the molecular structure include polyisoprene, partially hydrogenated polyisoprene, polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene chloride. Reacting with the functional group using as a starting material a polymer compound having such a molecular structure in the main chain and having at least one functional group selected from a hydroxyl group, an amino group, a carboxyl group, an isocyanate group, etc. at both ends A polymer having a higher molecular weight can be formed by a condensation reaction with a compound having a functional group. Moreover, the said functional group can also be used in order to introduce | transduce a polymerizable unsaturated group into the terminal.

Moreover, it is preferable that the number average molecular weights of resin (a) used for this invention are 1000-300,000. A more preferable range of the number average molecular weight of the resin (a) is 2000 or more and 100,000 or less, and a more preferable range is 5000 or more and 50,000 or less.
When the number average molecular weight of the resin (a) is 1000 or more, a cushion produced by crosslinking later maintains strength, and when printed on this cushion and used as a printing plate, it can withstand repeated use. . Further, when the number average molecular weight of the resin (a) is 300,000 or less, the viscosity at the time of molding of the photosensitive resin composition (A) does not increase excessively, and a sheet-like or cylindrical cushion is used. Can be produced. The number average molecular weight here is a value measured by gel permeation chromatography, calibrated with polystyrene having a known molecular weight, and converted.

  Furthermore, the resin (a) used in the present invention preferably has a polymerizable unsaturated group in the molecule. The “polymerizable unsaturated group” is a polymerizable functional group involved in a radical or addition polymerization reaction. As a particularly preferred resin (a), a polymer having an average of 0.3 or more polymerizable unsaturated groups per molecule can be mentioned. When the average number is 0.3 or more per molecule, the resulting cushion is excellent in mechanical strength. Furthermore, its durability is also good and it can withstand repeated use. Considering the mechanical strength of the cushion, the number of polymerizable unsaturated groups in the resin (a) is more preferably 0.5 or more per molecule, and even more preferably more than 0.7. In the resin (a) used in the present invention, the position of the polymerizable unsaturated group may be directly bonded to the end of the polymer main chain, the end of the polymer side chain, the polymer main chain, or the side chain. preferable. The average number of polymerizable unsaturated groups contained in one molecule of the resin (a) can be determined by a molecular structure analysis method using a nuclear magnetic resonance spectrum method (NMR method).

As a method for producing such a resin (a) having a polymerizable unsaturated group in the molecule, for example, it may be produced by directly introducing a polymerizable unsaturated group at the molecular end, Alternatively, a number having a plurality of reactive groups such as hydroxyl group, amino group, epoxy group, carboxyl group, acid anhydride group, ketone group, hydrazine residue, isocyanate group, isothiocyanate group, cyclic carbonate group, alkoxycarbonyl group, etc. Reaction of a compound having a molecular weight of about 1,000 and a binding agent having a plurality of functional groups capable of binding to these reactive groups (for example, polyisocyanate in the case of a hydroxyl group or an amino group) to adjust the molecular weight and bond at the end After the conversion to a functional group, the polymerizable unsaturated group is introduced into the terminal by reacting with a functional group that reacts with the terminal bonding group and an organic compound having a polymerizable unsaturated group. Methods such laws are preferably exemplified.
Also, it is produced by a method in which a polymerizable unsaturated group is introduced into a molecule by a chemical reaction such as a substitution reaction, elimination reaction, condensation reaction, addition reaction, etc., using a polymer compound having no polymerizable unsaturated group as a starting material. You can also. In this case, the polymer compound having no polymerizable unsaturated group as a starting material includes a polymer compound having a hetero atom in the main chain, a random copolymer synthesized from a plurality of types of monomer components, and a block copolymer. Can be mentioned. Furthermore, it is also possible to use a mixture of a plurality of polymer compounds having a polymerizable unsaturated group introduced in the molecule.

When the resin (a) is a liquid resin at 20 ° C, the photosensitive resin composition (A) is also liquid at 20 ° C, which is preferable. When the cushion obtained from this is molded into a sheet shape or a cylindrical shape, good thickness accuracy and dimensional accuracy can be obtained.
In particular, in order to produce a printing cushion used when a flexible relief image is required as in flexographic printing plate applications, as a resin (a), a liquid resin having a glass transition temperature of 20 ° C. or lower is further used. It is preferable to use a liquid resin having a glass transition temperature of 0 ° C. or lower. Examples of such a liquid resin include compounds having hydrocarbon chains such as polyethylene, polybutadiene, hydrogenated polybutadiene, and polyisoprene; polyester compounds having ester bonds such as adipate and polycaprolactone; compounds having an aliphatic polycarbonate structure; Examples thereof include compounds having a dimethylsiloxane skeleton. In particular, unsaturated polyurethanes having a polycarbonate structure are particularly preferred from the viewpoint of weather resistance.

The resin (a) used in the present invention has a chemical shift of 1. with respect to tetramethylsilane (TMS) in ¹ H-NMR (nuclear magnetic resonance spectroscopy using hydrogen atoms as observation nuclei) measurement. Hydrogen atoms having peaks in the range of 3 to 1.8 ppm, in the range of 4.0 to 4.3 ppm, and in the range of 4.5 to 5.5 ppm are 20% or more of all hydrogen atoms in the resin (a) 99 % Or less is preferable.
More preferably, they are 30% or more and 99% or less, More preferably, they are 40% or more and 99% or less. If the abundance ratio of the hydrogen atoms is in the range of 20% or more and 99% or less, the solvent resistance to the ester solvent or the solvent resistance to the ink containing the hydrocarbon solvent used in offset printing can be sufficiently secured. The mechanical strength as a cushion can be ensured.
The abundance ratio can be calculated from an integral value obtained in ¹ H-NMR measurement.

^{In 1} H-NMR, examples of the functional group structure around a hydrogen atom having a peak in a chemical shift range of 1.3 to 1.8 ppm include a methylene group of an aliphatic hydrocarbon chain.
Examples of the functional group structure present around a hydrogen atom having a peak in the chemical shift range of 4.0 to 4.3 ppm include an ester bond, an amide bond, a urethane bond, and a urea skeleton.
Furthermore, examples of the structure of a hydrogen atom having a peak in a chemical shift range of 4.5 to 5.5 ppm include a hydrogen atom directly bonded to a double bond carbon.

In the present invention, the organic compound (b) is a compound having a polymerizable unsaturated group. Here, the polymerizable unsaturated group refers to a radical or a functional group involved in an addition polymerization reaction.
The number average molecular weight is preferably 100 or more and less than 1000. The number average molecular weight is preferably less than 1000 because of easy dilution with the resin (a).

  Specific examples of the organic compound (b) used in the present invention include, as a compound having a group involved in radical reaction, 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; aryl compounds such as aryl alcohol and aryl isocyanate; unsaturated dicarboxylic acids such as maleic anhydride, maleic acid and fumaric acid and derivatives thereof; Vinyl acetates; N-vinyl pyrrolidone, N-vinyl carbazole and the like can be mentioned, and (meth) acrylic acid and derivatives thereof are preferred from the viewpoints of abundant types, price, decomposability upon laser light irradiation, and the like. Examples of the derivatives include alicyclic compounds having a cycloalkyl group, a bicycloalkyl group, a cycloalkenyl group, a bicycloalkenyl group, etc .; a benzyl group, a phenyl group, a phenoxy group, or a naphthalene skeleton, anthracene skeleton, biphenyl skeleton, phenanthrene Aromatic compounds having a skeleton, a fluorene skeleton, etc .; compounds having an alkyl group, halogenated alkyl group, alkoxyalkyl group, hydroxyalkyl group, aminoalkyl group, glycidyl group, etc .; alkylene glycol, polyoxyalkylene glycol, polyalkylene glycol, etc. Examples include ester compounds with polyhydric alcohols such as trimethylolpropane; compounds having a polysiloxane structure such as polydimethylsiloxane and polydiethylsiloxane. Moreover, you may be a heteroaromatic compound containing elements, such as nitrogen and sulfur.

In addition, cinnamoyl group, thiol group, azide group, epoxy group that undergoes ring-opening addition reaction, oxetane group, cyclic ester group, dioxirane group, spiroorthocarbonate group, spiroorthoester group, bicyclo Examples thereof include an ortho ester group and a cyclic imino ether group.
Examples of the compound having an epoxy group that undergoes an addition polymerization reaction include compounds obtained by reacting various diols and polyols such as triol with epichlorohydrin, and epoxy compounds obtained by reacting peracid with an ethylene bond in the molecule. Can do. Specifically, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene Glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, bisphenol A diglycidyl ether, hydrogenated bisphenol A Diglycidyl ether, bisphenol A Diglycidyl ether, polytetramethylene glycol diglycidyl ether, poly (propylene glycol adipate) diol diglycidyl ether, poly (ethylene glycol adipate) diol diglycidyl ether, poly (caprolactone) diol di of compounds with addition of lenoxide or propylene oxide Epoxy compounds such as glycidyl ether; epoxy-modified silicone oil (trade name “HF-105” manufactured by Shin-Etsu Chemical Co., Ltd.) can be mentioned.

In this invention, the organic compound (b) which has these polymerizable unsaturated groups can select 1 type (s) or 2 or more types. In order to suppress swelling with respect to organic solvents such as alcohols, esters, aliphatic hydrocarbons and the like as printing ink solvents, at least one kind of long-chain aliphatic, alicyclic or aromatic derivative is used as the organic compound (b). It is preferable to use it.
In order to increase the mechanical strength of the printing cushion obtained from the photosensitive resin composition (A), the organic compound (b) preferably has at least one alicyclic or aromatic derivative. In this case, the alicyclic or aromatic derivative is preferably 20% by weight or more, more preferably 50% by weight or more of the total amount of the organic compound (b). In addition, the aromatic derivative may be an aromatic compound having an element such as nitrogen or sulfur.

In the present invention, the photosensitive resin composition (A) can be photocured to exhibit physical properties as a binder for a printing cushion. In this case, a photopolymerization initiator (c) can be used.
The photopolymerization initiator (c) used in the present invention can be selected from those generally used. For example, radical polymerization exemplified in “Polymer Data Handbook-Fundamentals” edited by the Society of Polymer Sciences, published in 1986 by Baifukan. , Cationic polymerization, anionic polymerization photopolymerization initiator, and the like can be used. In addition, crosslinking by photopolymerization using the photopolymerization initiator (c) is useful as a method for producing a cushion with high productivity while maintaining the storage stability of the resin composition of the present invention. As specific examples of the photopolymerization initiator (c) for inducing radical polymerization reaction, a hydrogen abstraction type photopolymerization initiator and a decay type photopolymerization initiator are used as particularly effective photopolymerization initiators.

Although it does not specifically limit as a hydrogen abstraction type photoinitiator, It is preferable to use an aromatic ketone. Aromatic ketone is efficiently converted into an excited triplet state by photoexcitation, and a chemical reaction mechanism has been proposed in which this excited triplet state generates a radical by extracting hydrogen from the surrounding medium. The generated radical is considered to be involved in the photocrosslinking reaction. Any compound can be used as the hydrogen abstraction type photopolymerization initiator used in the present invention as long as it is a compound that extracts radicals from the surrounding medium through an excited triplet state to generate radicals. Examples of aromatic ketones include benzophenones, Michler ketones, xanthenes, thioxanthones, and anthraquinones, and it is preferable to use at least one compound selected from these groups.
Benzophenones refer to benzophenone or derivatives thereof, and specifically include 3,3 ′, 4,4′-benzophenone tetracarboxylic anhydride, 3,3 ′, 4,4′-tetramethoxybenzophenone, and the like. .
Michler ketones refer to Michler ketone and its derivatives. Xanthenes refer to derivatives substituted with xanthene and an alkyl group, phenyl group, halogen group or the like.
Thioxanthones refer to thioxanthone and derivatives substituted with alkyl groups, phenyl groups, halogen groups, and the like, and specific examples include ethylthioxanthone, methylthioxanthone, chlorothioxanthone, and the like. Anthraquinones refer to anthraquinone and derivatives substituted with alkyl groups, phenyl groups, halogen groups, and the like.
The addition amount of the hydrogen abstraction type photopolymerization initiator is preferably 0.1% by weight or more and 10% by weight or less, more preferably 0.5% by weight or more and 5% by weight or less of the total amount of the photosensitive resin composition. When the addition amount is within this range, when the liquid photosensitive resin composition is photocured in the air, the curability of the cured product surface can be sufficiently secured, and weather resistance can be secured.

The decay type photopolymerization initiator refers to a compound that generates an active radical by generating a cleavage reaction in the molecule after light absorption. In the present invention, the collapsible photopolymerization initiator is not particularly limited. Specific examples include benzoin alkyl ethers, 2,2-dialkoxy-2-phenylacetophenones, acetophenones, acyloxime esters, azo compounds, organic sulfur compounds, diketones, and the like. It is preferable to use at least one compound selected from the group consisting of: Examples of the benzoin alkyl ethers include compounds described in benzoin isopropyl ether, benzoin isobutyl ether, and “photosensitive polymer” (Kodansha, 1977, page 228). Examples of 2,2-dialkoxy-2-phenylacetophenones include 2,2-dimethoxy-2-phenylacetophenone and 2,2-diethoxy-2-phenylacetophenone. Examples of acetophenones include acetophenone, trichloroacetophenone, 1-hydroxycyclohexylphenylacetophenone, 2,2-diethoxyacetophenone, and the like. Examples of acyl oxime esters include 1-phenyl-1,2-propanedione-2- (o-benzoyl) oxime. Examples of the azo compound include azobisisobutyronitrile, diazonium compound, and tetrazene compound. Examples of organic sulfur compounds include aromatic thiols, mono- and disulfides, thiuram sulfides, dithiocarbamates, S-acyl dithiocarbamates, thiosulfonates, sulfoxides, sulfinates, dithiocarbonates, and the like. Examples of diketones include benzyl and methylbenzoyl formate.
The addition amount of the disintegration type photopolymerization initiator is preferably 0.1% by weight or more and 10% by weight or less, more preferably 0.3% by weight or more and 3% by weight of the total amount of the photosensitive resin composition (A) according to the present invention. % Or less. When the addition amount is within this range, when the photosensitive resin composition is photocured in the air, the curability inside the cured product can be sufficiently secured.

As the photopolymerization initiator (c), a compound having a site functioning as a hydrogen abstraction type photopolymerization initiator and a site functioning as a decay type photopolymerization initiator in the same molecule can also be used. Specific examples of such compounds include α-aminoacetophenones. Examples thereof include 2-methyl-1- (4-methylthiophenyl) -2-morpholino-propan-1-one and compounds represented by the following general formula (1).
General formula (1)
(In the formula, each R 2 independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. X represents an alkylene group having 1 to 10 carbon atoms.)
The amount of the compound having a site functioning as a hydrogen abstraction type photopolymerization initiator and a site functioning as a decay type photopolymerization initiator in the same molecule is 0.1 weight of the total amount of the photosensitive resin composition (A). % To 10% by weight, more preferably 0.3% to 3% by weight. If the addition amount is within this range, the mechanical properties of the cured product can be sufficiently ensured even when the photosensitive resin composition (A) is photocured in the atmosphere.

  As the photopolymerization initiator (c), a compound that induces an addition polymerization reaction by absorbing light and generating an acid can also be used. Examples of such compounds include photocationic polymerization initiators such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, or polymerization initiators that absorb light and generate bases. The addition amount of these photopolymerization initiators (c) is preferably in the range of 0.1 wt% or more and 10 wt% or less of the total amount of the photosensitive resin composition (A).

In the present invention, the ratio of the resin (a) and the organic compound (b) in the photosensitive resin composition (A) is 5 to 200 parts by weight of the organic compound (b) with respect to 100 parts by weight of the resin (a). It is preferable that it is 20 to 100 parts by weight. When 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 resulting cushion, and the shrinkage during photocuring is within a small range, thereby ensuring high thickness accuracy. be able to.
In the photosensitive resin composition (A) used in the present invention, a polymerization inhibitor, an ultraviolet absorber, a dye, a pigment, a lubricant, a surfactant, a plasticizer, a fragrance and the like can be added depending on the purpose and purpose. .

Such a photosensitive resin composition (A) is particularly preferably a liquid at 20 ° C. Liquid resin here means a polymer that has the property of being easily flow-fluctuated and solidifying into a deformed shape by cooling. When an external force is applied, the liquid resin is instantly deformed according to the external force. However, when external force is removed, the term corresponds to an elastomer having the property of recovering to its original shape in a short time.
It is preferable that the photosensitive resin composition (A) is in a liquid state because good thickness accuracy and dimensional accuracy can be obtained when it is formed into a sheet or cylinder. In the present invention, the photosensitive resin composition (A) preferably has a viscosity at 20 ° C. of 100 Pa · s to 50 kPa · s, more preferably 200 Pa · s to 20 kPa · s, and still more preferably, 200 Pa · s or more and 8 kPa · s or less.
If the viscosity of the photosensitive resin composition (A) is 100 Pa · s or more, the mechanical strength of the cushion produced thereby is sufficient, and it is easy to maintain the shape even when molded into a cylindrical cushion. Easy to process. On the other hand, if the viscosity is 50 kPa · s or less, it is easily deformed even at room temperature, easy to process, easily formed into a sheet-like or cylindrical cushion, and the process is simple.
In particular, when the photosensitive resin composition (A) is applied onto a cylindrical support to form a printing cushion, a phenomenon such as dripping occurs due to gravity in order to obtain a printing cushion with high plate thickness accuracy. Therefore, the viscosity of the photosensitive resin composition (A) is preferably 100 Pa · s or more, more preferably 200 Pa · s or more, and further preferably 500 Pa · s or more.
Moreover, when the photosensitive resin composition (A) used for this invention is liquid at 20 degreeC, it is preferable to have a thixotropic property. This is because, in particular, when the photosensitive resin composition layer is formed on the cylindrical support, a predetermined thickness can be maintained without causing dripping due to gravity.

The photosensitive resin composition (A) preferably contains hollow polymer particles or bubbles having an average diameter of 0.1 μm to 200 μm. The shape of such hollow polymer particles or bubbles need not be spherical, but is preferably spherical. The spherical shape includes a shape in which a true sphere is deformed by being compressed in at least one direction.
The average diameter of the hollow polymer particles or bubbles is preferably 1 μm or more and 150 μm or less, and more preferably 10 μm or more and 100 μm or less. When the average diameter of the hollow polymer particles or bubbles is within this range, it is possible to sufficiently absorb the impact due to the printing pressure applied to the printing plate during printing, and it is possible to obtain a high-quality printed matter.
When the hollow polymer particles are contained in the photosensitive resin composition (A), inorganic fine particles are used as the fine particles from the viewpoint of resistance to other compounds constituting the photosensitive resin composition (A) and handleability, Separately, it is particularly preferable to add inorganic ultrafine particles having an average diameter of less than 0.1 μm and to cause these to adhere to the surface of the hollow polymer particles. When inorganic fine particles or inorganic ultrafine particles are present on the surface of the hollow polymer particles, the hollow polymer particles are difficult to dissolve in the photosensitive resin composition (A), and can be stably stored for a long time. Moreover, the specific gravity of the hollow polymer particles is increased, and there is an effect that handling at the time of adding and mixing to the photosensitive resin composition (A) becomes easy.
The average diameter of the inorganic fine particles or ultrafine particles present on the surface is preferably in the range of 10 nm to 30 μm, more preferably 0.1 μm to 20 μm, and still more preferably 0.5 μm to 10 μm. Examples of the material of the inorganic fine particles or ultrafine particles include silica, alumina, calcium carbonate, zeolite, magnesium hydroxide, zirconium silicate and the like.

When bubbles are included in the photosensitive resin composition (A), it is preferable to mix ultrafine particles having an average diameter of 10 nm or more and less than 0.1 μm in order to make the bubbles stably exist. Although it does not specifically limit and may be the same material as microparticles | fine-particles, A silica, an alumina, a zeolite, a calcium carbonate, magnesium hydroxide, a zirconium silicate etc. can be mentioned. Ultrafine particles whose surface has been subjected to a hydrophobic treatment with a silane coupling agent or the like are preferable because they have an effect of stably holding bubbles for a long time. The content of the ultrafine particles is preferably 0.1% by weight or more and 10% by weight or less of the total weight of the photosensitive resin composition (A), and a more preferable range is 0.2% by weight or more and 5% by weight or less. More preferably, it is 0.5 weight% or more and 3 weight% or less.

In the present invention, as a method of mixing bubbles in the photosensitive resin composition (A), a method in which the liquid photosensitive resin composition (A) is forcibly stirred, air or an inert gas is used as the liquid photosensitive property. A method of jetting into the resin composition (A), a method of foaming the photosensitive resin composition (A) using a chemical foaming agent, and decompressing the gas dissolved in the liquid photosensitive resin composition (A) The foaming method etc. can be mentioned by making.
The bubbles may be open cells or closed cells, but from the viewpoint of securing mechanical properties, closed cells are more preferable. Here, an open cell refers to a bubble in a state where the bubbles are connected to each other, and a closed cell refers to a bubble in which each bubble exists independently. When the photosensitive resin composition is forcibly stirred, open cells are easily formed. In addition, when the photosensitive resin composition is foamed using a chemical foaming agent or when microcapsules are added to the photosensitive resin composition, closed cells are easily formed.

In the present invention, the thickness of the printing cushion or the printing cushion layer is not limited, but is preferably from 0.1 mm to 10 mm, more preferably from 0.3 mm to 5 mm.
The density of the printing cushion material is not limited, but it is preferably 0.2 g / cm ³ or more and 0.9 g / cm ³ or less, more preferably 0.2 g / cm ³ or more and 0.8 g / cm ^3. Hereinafter, it is more preferably 0.2 g / cm ³ or more and 0.7 g / cm ³ or less. If it is said range, it is possible to fully absorb the impact at the time of printing as a cushion.

By providing a layer made of the printing cushion material of the present invention on a support, a printing cushion can be obtained. The shape of the support is preferably a sheet shape or a cylindrical shape.
One of the roles of such a sheet-like or cylindrical support is to ensure the dimensional stability of the cushion. Therefore, it is preferable to select a support having high dimensional stability. Therefore, the linear thermal expansion coefficient of the support is preferably 100 ppm / ° C. or less, more preferably 70 ppm / ° C. or less.

  Here, examples of a method for reducing the linear thermal expansion coefficient of the support 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. it can. 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.

Specific examples of the support 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. Examples thereof include a resin, a liquid crystal resin composed of a wholly aromatic polyester resin, a wholly aromatic polyamide resin, and an epoxy resin. Further, these resins can be laminated and used. In addition, a porous sheet, for example, a cloth formed by knitting fibers, a nonwoven fabric, or a film in which pores are formed can be used as the sheet-like support. When a porous sheet is used as the sheet-like support, the cushion layer and the sheet-like support are integrated by photocuring after impregnating the photosensitive resin composition (A) into the pores, so that high adhesion is achieved. Sex can be obtained. The fibers forming the cloth or non-woven fabric include glass fibers, alumina fibers, carbon fibers, alumina / silica fibers, boron fibers, high silicon fibers, potassium titanate fibers, sapphire fibers, and other natural fibers such as cotton and linen. Fibers: Semi-synthetic fibers such as rayon and acetate; and synthetic fibers such as nylon, polyester, acrylic, vinylon, polyvinyl chloride, polyolefin, polyurethane, polyimide, and aramid. Further, cellulose produced by bacteria is a highly crystalline nanofiber, and is a material capable of producing a thin nonwoven fabric with high dimensional stability.
In the case of a cylindrical support, a cylindrical support made of fiber reinforced plastic (FRP), plastic or metal can also be used. The cylindrical support can be hollow with a constant thickness for weight reduction. In the present invention, the cylindrical support may be a rigid support or a flexible support.

In the present invention, as a method for forming a layer made of a cushioning material for printing on a support, for example, a resin composition containing fine particles and a photosensitive resin composition (A) is formed into a layer on the support, The method of hardening this by light irradiation is mentioned. An existing resin molding method can be used as a method of molding the resin composition containing the fine particles and the photosensitive resin composition (A) into a layer. 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.
When forming into a cylindrical shape, organic films such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, polyamide, polysulfone, polyether ether ketone, polyphenylene ether, polyphenylene thioether, nickel, chromium, iron, After forming on a sheet-like support made of metal such as copper, titanium, or aluminum, it may be attached to a cylindrical cylinder or directly on a cylinder of a printing press.

In the present invention, adhesion to a layer made of a cushioning material for printing can be improved by performing physical and chemical treatment on the surface of the sheet-like or cylindrical support. 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. Examples of chemical treatment methods include strong acid / strong alkali treatment methods, oxidant treatment methods, and coupling agent treatment methods.
A printing cushion in which a layer of such a printing cushion material is formed on a support is such that the support is located on the cylinder side of the printing press, i.e. cylinder / support / printing cushion layer / printing. It is preferable to arrange and use them in the order of the plates.

  The cushion layer and the printing cushion made of the printing cushion material of the present invention may be laminated and used. For example, two or more printing cushions made of the printing cushion material of the present invention may be stacked, or may be combined with a cushion such as a commercially available polyethylene foam or polyurethane foam prepared by known means. Absent. Here, there is no restriction | limiting in particular in the material of the foam produced by a known means. When the cushions for printing are used in layers, there is no particular limitation on the order of lamination.

  The total thickness of the total laminated printing cushions or cushion layers is preferably from 0.1 mm to 10 mm, and more preferably from 0.2 mm to 5 mm. Within this range, it is possible to sufficiently absorb the impact during printing as a cushion.

A printing plate layer can be obtained by laminating a printing plate layer on a printing cushion layer made of the printing cushion material of the present invention.
Moreover, it can also be set as a printing original plate by laminating | stacking a printing original plate layer on the printing cushion layer which consists of the cushion material for printing of this invention. An uneven pattern is formed on the surface of the printing original plate, whereby a printing plate can be obtained. The pattern forming method is not particularly limited. For example, a photosensitive resin composition (B) layer is used as a printing original plate layer, and this is subjected to exposure and development processes. A composition (C) layer is used, and this is subjected to drawing, exposure, and development processes using a laser drawing machine. CTP plate making technology (Computer-to-plate), and a photosensitive resin composition (E) layer as a printing original plate layer Use this by exposing it with a laser drawing machine or photoengraving technology, and patterning it using heat development platemaking technology, or using a cured resin layer as a printing original plate layer, and irradiating it with laser light to make resin A laser engraving method that directly removes can be mentioned. The laser engraving method is an extremely simple method because it does not require a development step for removing the uncured resin.

  When the photosensitive resin composition (A) is used as the binder resin for the printing cushion material, the photosensitive resin compositions (B) to (E) and the photosensitive resin composition (A) for forming the printing original plate layer or the printing plate layer are used. ) Is preferably different in composition. Here, “differing in composition” includes not containing bubbles or fine particles.

  A method for laminating a printing plate layer or a printing original plate layer on a printing cushion layer is a method in which a resin for directly forming a printing plate or a printing original plate layer is applied on a printing cushion, a sheet-like printing plate or a printing original plate Can be mentioned through an adhesive layer.

  In the case of a laser engraving printing original plate, as a material of the printing original plate layer, a crosslinked natural rubber, a crosslinked synthetic rubber, a thermosetting resin cured product, a photosensitive resin cured product, or the like can be used. Among them, a cured photosensitive resin is preferable, and such a printing original plate layer is formed by laminating a photosensitive resin for a printing original plate on a printing cushion, and then curing the photosensitive resin by irradiating light on the entire surface. It is particularly preferable to form a physical layer from the viewpoint of ensuring print quality or ensuring moldability.

  The thickness of the printing plate layer or printing original plate layer formed on the printing cushion layer may be arbitrarily set according to the purpose of use, but is preferably 0.1 to 7 mm. In some cases, a plurality of materials having different compositions may be stacked. For example, in the case of a laser engraving printing original plate, a layer that can be engraved using a laser having an oscillation wavelength in the near-infrared region such as a YAG laser, a fiber laser, or a semiconductor laser is formed on the outermost surface, and a carbonic acid is formed under the layer. It is also possible to form a layer capable of laser engraving using an infrared laser such as a gas laser or a visible / ultraviolet laser. By forming such a laminated structure, a relatively high-power carbon dioxide laser is used to deeply engrave a relatively rough pattern, and a very fine pattern near the surface is used using a near-infrared laser such as a YAG laser or fiber laser. Can be engraved. Since an extremely fine pattern may be engraved relatively shallowly, the thickness of the layer sensitive to the near infrared laser is preferably in the range of 0.01 mm to 0.5 mm. Thus, by laminating a layer sensitive to the near infrared laser and a layer sensitive to the infrared laser, the depth of the pattern engraved using the near infrared laser can be accurately controlled. This is because a layer that is sensitive to an infrared laser utilizes a phenomenon that is difficult to engrave with a near infrared laser. The difference in the fineness of the engraving pattern is caused by the difference in the oscillation wavelength inherent to the laser device, that is, the difference in the diameter of the laser beam that can be narrowed. When laser engraving is performed in this way, engraving can be performed using separate laser engraving equipment equipped with infrared laser and near infrared laser, and laser engraving equipment equipped with both infrared laser and near infrared laser can be used. It is also possible to use.

  In laser engraving, a relief image can be created on an original by operating a laser apparatus using a computer as an image to be formed as digital data. Any laser may be used for the laser engraving as long as the original plate includes a wavelength having absorption, but in order to perform engraving at a high speed, a laser with a high output is desirable. Infrared or infrared emitting solid lasers such as YAG lasers and semiconductor lasers are preferred. In addition, the second harmonic of a YAG laser having an oscillation wavelength in the visible light region, a copper vapor laser, an ultraviolet laser having an oscillation wavelength in the ultraviolet region, such as an excimer laser, and a YAG laser wavelength-converted to the third or fourth harmonic are It can be ablated by cutting the bonds of organic molecules and is suitable for fine processing. The laser may be continuous irradiation or pulse irradiation. In general, resin has absorption in the vicinity of 10 μm of carbon dioxide laser, so it is not essential to add a component that helps the absorption of laser light, but YAG laser has a wavelength in the vicinity of 1.06 μm. There is not much that has. In that case, it is preferable to add a dye or a pigment, which is a component that assists in the absorption thereof. Examples of such dyes include poly (substituted) phthalocyanine compounds and metal-containing phthalocyanine compounds, cyanine compounds, squarylium dyes, chalcogenopyrroloarylidene dyes, chloronium dyes, metal thiolate dyes, bis (chalcogenopyrrillo) polymethine dyes, oxyindo Examples include lysine dyes, bis (aminoaryl) polymethine dyes, merocyanine dyes, and quinoid dyes. Examples of pigments include dark inorganic pigments such as carbon black, graphite, copper chromite, chromium oxide, cobalt chrome aluminate, copper oxide and iron oxide, and metal powders such as iron, aluminum, copper and zinc, and these metals. And those doped with Si, Mg, P, Co, Ni, Y or the like. These dyes and pigments may be used alone, in combination of a plurality, or in any form such as a multilayer structure. However, in the case of a system in which the photosensitive resin composition is cured using light, the amount of the organic / inorganic compound that absorbs a large amount of light at the wavelength of light used for curing should be within a range that does not hinder the photocurability. The addition ratio with respect to the total amount of the photosensitive resin composition is preferably 5% by weight or less, more preferably 2% by weight or less.

  Laser engraving is performed in an oxygen-containing gas, generally in the presence of air or an air stream, but can also be performed in a carbon dioxide gas or a nitrogen gas. After engraving, the powdery or liquid substance slightly generated on the relief printing plate surface is irradiated with an aqueous cleaning agent by an appropriate method, for example, a method of washing with water containing a solvent or a surfactant, or a high-pressure spray. You may remove using the method, the method of irradiating a high pressure steam, etc.

  After the concave / convex pattern is formed by laser engraving, post-exposure can be performed by irradiating the surface of the printing plate on which the pattern is formed with light having a wavelength of 200 nm to 450 nm. This is an effective method for removing tack on the surface. The post-exposure may be performed in any environment such as air, inert gas atmosphere, and water. This is particularly effective when the photosensitive resin composition used contains a hydrogen abstraction type photopolymerization initiator. Furthermore, before the post-exposure step, the printing plate surface may be exposed to a treatment liquid containing a hydrogen abstraction type photopolymerization initiator. Moreover, you may expose in the state which immersed the printing plate in the process liquid containing a hydrogen abstraction type photoinitiator.

The present invention will be described in more detail with reference to the following examples and comparative examples of the present invention, but these are illustrative, and the present invention is not limited to the following examples. Those skilled in the art can implement the present invention by making various modifications to the embodiments shown below, and such modifications are included in the scope of the claims of the present application.
(1) Measurement of viscosity The viscosity of the photosensitive resin composition was measured at 20 ° C. using a B-type viscometer (trademark, B8H type; manufactured by Tokyo Keiki Co., Ltd., Japan). The viscosity of the resin was measured at 50 ° C.
(2) Measurement of the number average molecular weight of the resin (a) The number average molecular weight of the resin (a) was determined by converting it into polystyrene having a known molecular weight using a gel permeation chromatography method (GPC method). Using a high-speed GPC device (trade name, HLC-8020, manufactured by Tosoh Corporation, Japan) and a polystyrene packed column (trademark: TSKgel GMHXL; manufactured by Tosoh Corporation, Japan), the measurement was performed with tetrahydrofuran (THF). The column temperature was set to 40 ° C. As a sample to be injected into the GPC apparatus, a THF solution having a resin concentration of 1% by weight was prepared, and the injection amount was 10 μl. Further, a resin ultraviolet absorption detector was used as a detector, and light at 254 nm was used as monitor light.
(3) Measurement of the number of polymerizable unsaturated groups After the average number of polymerizable unsaturated groups present in the molecule of the resin (a) is removed using a liquid chromatographic method, unreacted low molecular components are removed. It was determined by molecular structure analysis using nuclear magnetic resonance spectroscopy (NMR method).
(4) Measurement of storage elastic modulus (G ′), loss elastic modulus (G ″), tan δ Storage elastic modulus (G ′) of printing cushion material formed from the photosensitive resin composition (A) at 20 ° C. and 400 Hz. ), Loss elastic modulus (G ″) and tan δ were measured by the following procedure using a dynamic viscoelasticity measuring device AR-550 (trade name, manufactured by Rheometric Scientific F.E. Co., Ltd.).
A transparent polyester film having a thickness of 100 μm and silicon-treated on a cylindrical support made of fiber-reinforced plastic having an outer diameter of 230.00 mm and a width of 300 mm was attached. A photosensitive resin composition for producing a cushion material for printing is adjusted on the polyester film so that the thickness after curing is 1.0 mm and coated with a doctor blade, and a metal halide lamp (I Graphics, Inc.) is applied to the polyester film. (Trade name “M056-L21”) was irradiated with 4000 mJ / cm 2 (energy amount integrated using a UV meter and a UV-35-APR filter) and cured to obtain a printing cushion material for measurement. Next, this is cut into a size of 10 mm in width and 35 mm in length, a sample is set in the shear type geometry of the dynamic viscoelasticity measuring device AR-550, the effective measurement thickness is 1 mm, the effective measurement diameter is 9 mm, The value of the storage elastic modulus and loss elastic modulus when the strain amplitude is 0.5% and the measurement frequency is changed in a range of 0.1 Hz to 20 Hz as a sine wave is −10 from the measurement temperature of 30 ° C. to −20 ° C. Measured at each ° C, and according to the application of the apparatus, a master curve was created at a reference temperature of 20 ° C on the temperature / time conversion side, and a tan δ value at 400 Hz was read.
(5) Preparation of printing plate The solvent-developable unexposed photosensitive resin plate Cyrel HIQS (manufactured by DuPont, product name, thickness 1.14 mm) is peeled off, and the protective film layer on the photosensitive resin layer is peeled off. A negative film is closely attached to the surface, and then an entire surface exposure of 330 mJ / cm ² is performed from the support side using an ultraviolet fluorescent lamp having a center wavelength of 370 nm on an AFP-1500 exposure machine (trade name, manufactured by Asahi Kasei). Subsequently, image exposure at 6000 mJ / cm ² was performed through a negative film. The exposure intensity at this time was measured on the glass plate for ultraviolet rays from the lower lamp, which is the side that performs back exposure, using a UV illuminometer MO-2 type machine manufactured by Oak Seisakusho using a UV-35 filter. The intensity was 4.0 mW / cm ² , and the intensity measured by ultraviolet rays from the upper lamp on the relief exposure side was 7.8 mW / cm ² . Next, development was performed at a liquid temperature of 30 ° C. using a quick line 912 developing machine (trade name, manufactured by Asahi Kasei) using Sorbit (trade name, manufactured by MacDermid) as a developer.
Immediately after development, the plate is swollen in the developer, and is dried at 60 ° C. for 1 hour before post-exposure. Thereafter, the entire plate surface is 1000 mJ / cm ² using a germicidal lamp having a central wavelength of 254 nm. Then, 1000 mJ / cm ² was post-exposed using an ultraviolet fluorescent lamp to obtain a sheet-like flexographic printing plate. In addition, the post-exposure amount by a germicidal lamp here is computed from the illumination intensity measured using the UV-25 filter of MO-2 type machine.
(6) Printability evaluation test The printing plate manufactured in (5) and the cushions for printing made of the cushioning materials for printing in Examples 1 to 7 and Comparative Examples 1 and 2 were used as flexographic printing machines (manufactured by KR, UK). A cushion layer for printing / double-sided tape (manufactured by 3M, ST-416, trade name) / printing plate is attached in this order on a plate cylinder of the trademark “FLEXPROOF100”, and the wire number of 150 lpi is 20% shown in FIG. Negative film patterns having halftone dots of 30%, 40% and 50% (each size is 5 mm × 220 mm) and a solid portion (3 mm × 240 mm) were printed. The printing speed was 60 m / min, the anilox roll was 1000 lpi, and a single-side coated paper having a weight of 86.5 g / m ² was used as a printing medium.
The print quality (density unevenness) is determined by using the image analysis apparatus (trademark “LUZEX”, manufactured by NIRECO Co., Ltd.) for the darkest part and the thinnest part of the 30% halftone dots in the pattern of FIG. Was measured, and a “shade ratio” was calculated according to the following formula and evaluated using this. At this time, the lens magnification and the measurement position were adjusted so that at least 50 halftone dots were included in the measurement visual field.
In the density ratio of the above formula, the average area ratio of the density difference is calculated (numerator), and it is divided by the average area ratio value (denominator) of the entire halftone dot area, thus eliminating the dot fat factor be able to. That is, even if the dot thickness is affected by the difference in added fine particles or the difference in printing pressure, the density unevenness of the halftone dots can be detected. The lower the density ratio, the smaller the density unevenness of the halftone dots.

[Production example]
(Preparation of resin (a1))
To be used as the resin (a), a 2 L separable flask equipped with a thermometer, a stirrer, and a refluxer is added to a trademark “PCDL T4672” (number average molecular weight 2063, OH value 54.4) which is a polycarbonate diol manufactured by Asahi Kasei Corporation. ) 875 g and tolylene diisocyanate 53.7 g were added and reacted at 80 ° C. for about 3 hours, followed by addition of 36.9 g of 2-methacryloyloxyisocyanate and further reaction for about 3 hours. A resin (a1) having a number average molecular weight of about 8000, which was a methacrylic group (average number of polymerizable unsaturated groups in the molecule of about 1.7 per molecule) was produced. This resin was in the shape of a syrup at 20 ° C., flowed when an external force was applied, and did not recover its original shape even when the external force was removed.
^{In 1} H-NMR (nuclear magnetic resonance spectroscopy using hydrogen atoms as observation nuclei) measurement, when tetramethylsilane (TMS) is used as a reference, the chemical shift is in the range of 1.4 to 1.7 ppm, 4.0. The abundance ratio of hydrogen atoms having peaks in the range of ˜4.3 ppm and in the range of 4.5 to 5.5 ppm to the total hydrogen atoms of the resin (a1) was 40%.

(Preparation of photosensitive resin composition (A1))
To 50 parts by weight of the resin (a1), 25 parts by weight of phenoxyethyl methacrylate and 25 parts by weight of phenoxyethyl acrylate were added as the organic compound (b). As a photopolymerization initiator (c), 0.5 part by weight of 2,2-dimethoxy-2-phenylacetophenone (DMPAP), which is a decay type photopolymerization initiator, was added. As other additives, 0.6 parts by weight of 2,6-di-t-butyl-4-methylphenol and 1 part by weight of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate were added. A liquid resin composition was prepared at 20 ° C. The resin composition was liquid at 20 ° C. The viscosity measured using a B-type viscometer was 80 Pa · s or less at 20 ° C.
For 100 parts by weight of the resin composition, 16 g of capsule-shaped fine particles (manufactured by Matsumoto Yushi Co., Ltd., trademark “MFL100CA”) having an average diameter of about 100 μm that have already been expanded are used as hollow polymer particles using a planetary kneader. And mixed to prepare a photosensitive resin composition (A1). The capsule-shaped fine particles had calcium carbonate fine particles attached to the surface, and the true specific gravity was 0.134 g / cm 3.
The photosensitive resin composition (A1) was liquid at 20 ° C. The viscosity measured using a B-type viscometer was 4000 Pa · s or less at 20 ° C.

[Example 1]
To 100 parts by weight of the photosensitive resin composition (A1) prepared in Production Example 1, 5 parts by weight of silicone rubber “KMP-602” (manufactured by Shin-Etsu Chemical Co., Ltd.) is added as fine particles to prepare a planetary kneader. And mixed to obtain a resin composition for producing a cushion material for printing.
Next, a 100 μm thick transparent and silicon-treated polyester film is pasted on a cylindrical support made of fiber-reinforced plastic having an outer diameter of 230.00 mm and a width of 300 mm, and a cushioning material for printing is produced on the polyester film. The resin composition was adjusted so that the thickness after curing was 0.4 mm, and coated with a doctor blade. The metal halide lamp (trade name “M056-L21” manufactured by Eye Graphics Co., Ltd.) was irradiated with 4000 mJ / UV. Irradiated with cm @ 2 (energy amount accumulated using a UV meter and a UV-35-APR filter) and cured to obtain a printing cushion material for printability evaluation.

[Example 2]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that the glass micro hollow body “Z-27” (trade name, manufactured by Tokai Kogyo Co., Ltd.) was used as the fine particles.

[Example 3]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that the micro glass hollow body “S60” (manufactured by 3M, trade name) was used as the fine particles.

[Example 4]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that the soft fluororesin “Cefal SG150F200F” (trade name, manufactured by Central Glass Co., Ltd.) was used as the fine particles.

[Example 5]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that mica “WG160” (trade name, manufactured by Shiraishi Calcium Co., Ltd.) was used as the fine particles.

[Example 6]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that cold water “NN # 200” (trade name, manufactured by Nitto Flour Industry Co., Ltd.) was used as the fine particles.

[Example 7]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that calcium carbonate “WS-K” (manufactured by Takehara Chemical Industry Co., Ltd., trade name) was used as the fine particles.

[Comparative Example 1]
A cushion material for sheet-like printing was prepared in the same manner as in Example 1 except that fine particles were not added.

[Comparative Example 2]
As a cushion material for printing, a commercially available polyethylene (PE) -based high hardness cushion tape manufactured by S company was used. In addition, when attaching the printing cushion which consists of this printing cushion material, the double-sided tape was not used.

From Table 1, when the cushion material for printing containing the fine particles of Examples 1 to 7 corresponding to the present invention is used as the printing cushion, the printing material containing no fine particles of Comparative Example 1 and Comparative Example 2 is used. Compared with the case where the cushion material was used, it was confirmed that the density ratio was low and the density unevenness was reduced. In addition, there was no significant difference in solid quality in any printed matter of Example and Comparative Example.

The cushion material for printing of the present invention includes a relief image for a mold material of ceramic products, a relief image for a display such as an advertisement / display board, a relief image for patterning an insulator / resistor / conductor paste used for making an electronic component, etc. Printing plates with relief images; printing plates used for patterning functional materials such as antireflection films, color filters and (near) infrared absorption filters for optical components; in the manufacture of display elements such as liquid crystal displays or organic electroluminescent displays Printing plates used for pattern formation of coating films such as alignment films, undercoat layers, light emitting layers, electron transport layers, sealant layers, etc .; screen printing plates; cushion layers of various printing plates such as rotary screen printing plates, and these Can be used to produce printing cushions used in combination with printing plates That.
In particular, the present invention can be suitably used as a material for producing a printing cushion or a printing cushion layer that improves printing quality in the field of flexographic printing.

Print pattern used for printability evaluation test

Claims (13)

  A cushioning material for printing containing fine particles having an average diameter of 0.1 μm to 100 μm. The cushion material for printing according to claim 1, wherein the specific gravity of the fine particles is 0.1 g / cm ³ or more and 3.0 g / cm ³ or less.   The cushioning material for printing according to claim 1 or 2, wherein a loss tangent (tan δ) at 20 ° C and 400 Hz is 0.2 or more and 0.8 or less.   The cushion material for printing of any one of Claim 1 to 3 containing the photocured material of the photosensitive resin composition as a binder.   The photosensitive resin composition is a photosensitive resin composition (A) containing a resin (a), an organic compound (b) and a photopolymerization initiator (c), and the resin (a) is contained in the molecule. The cushion material for printing of Claim 4 which has a carbonate bond. When the resin (a) is measured by ¹ H-NMR (nuclear magnetic resonance spectroscopy using hydrogen atoms as observation nuclei), the chemical shift is 1.3 to 1. The abundance ratio of 20% or more and 99% or less of the total hydrogen atoms of the resin (a) having hydrogen atoms having peaks in the range of 8 ppm, in the range of 4.0 to 4.3 ppm, and in the range of 4.5 to 5.5 ppm. The cushioning material for printing according to claim 5, which is contained in   The photosensitive resin composition (A) is liquid at 20 ° C. and contains hollow capsule particles having a number average particle diameter of 0.1 μm or more and 200 μm or less or bubbles having an average diameter of 0.1 μm or more and 200 μm or less, The cushioning material for printing according to claim 5 or 6, wherein the viscosity at 20 ° C is 100 Pa · s or more and 50 kPa · s or less.   The cushioning material for printing according to any one of claims 5 to 7, wherein the photosensitive resin composition (A) further contains ultrafine particles having an average primary particle diameter of 10 nm or more and less than 0.1 µm. The cushion material for printing according to any one of claims 1 to 8, wherein the density is 0.2 g / cm ³ or more and 1.3 g / cm ³ or less.   A printing cushion obtained by molding the printing cushion material according to claim 1 into a hollow cylindrical shape.   A printing cushion having at least one layer made of the cushioning material for printing according to any one of claims 1 to 9.   The printing original plate or printing plate which has a layer which consists of cushion materials for printing of any one of Claim 1 to 9.   The printing original plate or printing plate of Claim 12 with which a pattern is formed by the laser engraving method.