JP2010023305A - Method of manufacturing printing plate by inkjet process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a printing plate by the inkjet process which takes advantage of the facility and high productivity of the inkjet process, and contributes to eliminating the phenomenon of ink liquid droplet gathering due to coalescence as a conventional problem in the manufacturing of a printing plate by the inkjet process, as well as exhibiting excellent inking properties during an initial printing stage. <P>SOLUTION: This method of manufacturing a printing plate by the inkjet process is to make a deposition of an ink for forming a printing plate containing at least, water, a water-soluble organic solvent and a resin micro particle on a heated printing material for printing by inkjet process, and thus, form an image. In addition, the acid value of the resin micro particle contained in the ink for forming the printing plate, is not more than 30 mgKOH/g. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet plate making method, and more particularly to an ink jet plate making method used for producing a printing plate for forming an image by a computer-to-plate (CTP) method.

  With the digitization of print data, there is a need for a CTP that is inexpensive, easy to handle, and has the same printability as the PS plate. In particular, in recent years, various types of CTP using infrared laser recording have been proposed. Among them, so-called dry CTP (including development on a printing press) that does not require special development processing has attracted attention. However, these systems require a great deal of energy for image formation, and the exposure apparatus is also expensive.

  On the other hand, CTP has also been proposed in which an oleophilic image is directly formed on a substrate having a hydrophilic surface by an ink jet method and a printing plate is produced without a special development treatment. For example, oil-based ink is used as a printing plate material. There is a method (for example, refer to Patent Document 1) in which a resin that adheres to the top and is made to correspond to the image after drying is used, but the printing durability is insufficient, and the ink that adheres on the printing plate Before the droplets dried, there was a problem that so-called beading was caused and the resolving power was lowered.

  In addition, solid ink systems described in JP-A-11-139016 and 11-139017, and photocurable ink using a photocurable monomer are applied to a printing plate material to form an image, and light irradiation Discloses a UV curing type plate making method for curing an image portion (see, for example, Patent Document 2). However, the solid ink method and the solvent-free type with no evaporation component such as the UV method, and the method of solidifying the entire ink, has a structure in which the image area is raised with respect to the non-image area. In other words, there is a problem that a dot gain phenomenon in which even ink is transferred easily occurs.

In addition, in Japanese Patent Application No. 2006-197822, the present applicant has proposed a plate making method in which resin fine particles are contained together with a water-soluble polymer that forms a crosslinked structure by irradiation with water and active energy rays. Is not characterized by heating, and when trying to print at high speed on a grained aluminum plate, sufficient beading cannot be prevented and a phenomenon such as liquid drift may occur, There was a need for further improvement as a printing plate image. Furthermore, in this method, the ink ink has poor adhesion to the image area, and the phenomenon that the printing ink does not easily get on at the time of printing is scattered. I had a problem to improve.
JP-A-56-62157 JP 2007-314632 A

  The present invention has been made in view of the above-mentioned problems, and its purpose is to improve the liquid closeness due to the coalescence of ink droplets, which is a problem in the plate making of the ink jet method, utilizing the convenience and high productivity of the ink jet method. It is another object of the present invention to provide a plate making method having excellent inking properties at the time of printing.

  The above object of the present invention is achieved by the following configurations.

  1. In an ink-jet plate making method for forming an image by adhering a plate-forming ink containing at least water, a water-soluble organic solvent and resin fine particles onto a heated printing plate material using an ink-jet method, the plate-forming ink An ink plate making method, wherein the acid value of the resin fine particles contained in is 30 mgKOH / g or less.

  2. 2. The ink jet plate making method according to 1 above, wherein the plate forming ink contains a solid dispersion dispersed using a polymer dispersant, and the printing plate material is heated to form an image after printing. .

  3. 3. The inkjet plate making method according to 1 or 2, wherein the resin film surface formed on the printing plate material using the plate forming ink has a receding contact angle with respect to water of 40 ° or more.

  4). The polymer contains a polymer compound having a plurality of side chains in the main chain and capable of crosslinking between side chains by irradiating with active energy rays. Any one of 1 to 3 above, wherein the main chain of the molecular compound is a saponified product of polyvinyl acetate, the saponification degree is 77% or more and 99% or less, and the polymerization degree is 200 or more and 4000 or less. The inkjet plate-making method as described in a term.

  5. After the plate forming ink is deposited on the printing plate material by the inkjet method, the plate forming ink is irradiated with active energy rays, and the ink solvent is evaporated and dried to form an image and print. 5. The ink-jet plate making method according to any one of 1 to 4, wherein a plate is produced.

  The present invention makes use of the convenience and high productivity of the ink jet system, improves the liquid dipping due to coalescence of ink droplets, which has been a problem in ink jet system plate making, and has excellent inking properties at the time of printing. Could be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor adhered at least a plate-forming ink containing water, a water-soluble organic solvent, and resin fine particles onto a heated printing plate material using an inkjet method. In the ink jet plate making method for forming an image, the acid value of the resin fine particles contained in the plate forming ink is 30 mgKOH / g or less. As a result, the present inventors have found that it is possible to realize a plate-making method that improves liquid drift due to coalescence of ink droplets, which has been a problem in ink-jet type plate-making, and has excellent inking properties during printing. is there.

  That is, as a result of intensive studies on the above problems by the present inventor, the plate is formed by using ink containing resin fine particles having an acid value of a predetermined value or less on a pre-heated printing plate material, thereby making the liquid close. I found out that it can be prevented. In addition, the inking property at the time of printing was found to have a good correlation with the receding contact angle with respect to water in the image area. Furthermore, it has been found that heating the plate in advance increases the receding contact angle with respect to the water in the image area, thereby solving the problem of inking.

  In particular, when using a polymer dispersant for pigment dispersion, it was found that heating the plate during and after printing increases the receding contact angle and increases the hydrophobicity of the image area. .

  This indicates that the physical properties of the surface of the image area have been changed by heating, and the image line formed by the resin fine particles is probably the free dispersant derived from the pigment dispersion or the pigment particles adsorbed by the dispersant. It is presumed that the surface has become more hydrophobic as a result of being gradually taken into the interior with heating.

  Details of the present invention will be described below.

[Resin fine particles]
The plate forming ink (hereinafter also simply referred to as ink) according to the present invention is characterized by containing resin fine particles having an acid value of 30 mgKOH / g or less together with water, a coloring material, and a water-soluble organic solvent.

  The resin fine particles applicable to the ink according to the present invention are not particularly limited as long as the acid value is 30 mg KOH / g or less, but preferably polyurethane, polystyrene-acryl, polystyrene-butadiene, polystyrene-maleic acid, polyester, poly Fine resin particles made of ether, polycarbonate, polyamide, polyacrylonitrile, polystyrene, polybutadiene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, acrylic modified silicone resin, acrylic modified fluororesin, or the like Examples thereof include resin fine particles comprising these copolymers and salts thereof, and preferably from at least one of polyurethane, polystyrene-acryl, polystyrene-butadiene, polystyrene-maleic acid. Copolymers thereof that barrel. For example, the polystyrene-acrylic resin fine particles include Joncrill series (manufactured by BASF), and the polyurethane resin fine particles include polyester-based, polyether-based, polycarbonate-based, aromatic isocyanate-based, etc. More preferred are polyethers and polycarbonates. Specifically, Superflex series (Daiichi Kogyo Seiyaku Co., Ltd.), Permarin UA series (Sanyo Kasei Co., Ltd.), etc. are mentioned.

  The resin fine particles according to the present invention may be either a forced emulsification type forcibly emulsified with an emulsifier, or a self-emulsification type in which a hydrophilic group or a hydrophilic segment is imparted and dispersed in a resin. A surfactant is often used as an emulsifier, but a polymer having a hydrophilic group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer having a hydrophilic group grafted thereto, a monomer having a hydrophilic part, It is also preferable to use a polymer obtained from a monomer having a hydrophobic portion.

  In recent years, as latex polymer particles, there are also latexes in which core-shell type polymer particles having different compositions at the center and outer edge of the particles are dispersed in addition to the latex in which the polymer particles are uniform throughout. However, this type of latex can also be preferably used.

  In the ink according to the present invention, the average particle size of the resin fine particles is preferably 10 nm or more and 200 nm or less, more preferably 10 nm or more and 150 nm or less. If the average particle diameter of the resin fine particles is 10 nm or more, the storage stability is excellent, and if it is 200 nm or less, good gloss can be obtained. The average particle size of the resin fine particles can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, a laser Doppler method, or the like.

  Further, in the ink according to the present invention, the content of the resin fine particles according to the present invention is preferably 5% by mass or more and 200% by mass or less, more preferably 10% by mass or more and 200% by mass with respect to the color material. % Or less. If the content of the resin fine particles according to the present invention is 5% by mass or more with respect to the color material, sufficient scratch resistance and water resistance can be obtained, and if it is 200% by mass or less, the nozzle is clogged. Therefore, the continuous emission is improved.

  In the present invention, the acid value of the resin fine particles according to the present invention is 30 mgKOH / g or less, preferably 20 mgKOH / g or less, more preferably 10 mgKOH / g or less.

  The acid value as used in the present invention generally refers to the number of mg of potassium hydroxide required to neutralize free fatty acids such as carboxyl groups and sulfone groups contained in 1 g of a sample. The acid value can also be obtained by calculation from the neutralizable carboxyl group amount used as a raw material monomer during resin fine particle synthesis.

  The acid value according to the present invention is measured according to the method described in JIS K0070-1992 (neutralization titration method). Specifically, resin fine particles are diluted 50 times with methyl cellosolve and titrated with 0.1 mol / L potassium hydroxide. The inflection point of the pH curve obtained using a pH meter is taken as the neutralization point. The acid value is calculated from the amount of potassium hydroxide required to reach this neutralization point.

(Water-soluble organic solvent)
The solvent constituting the ink according to the present invention contains at least water and a water-soluble organic solvent.

  Examples of water-soluble solvents applicable to the ink according to the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol), polyhydric alcohols (for example, Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), polyhydric alcohol ethers (for example, ethylene) Glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Cole monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylene) Tetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2 -Pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (for example, dimethyl sulfoxide) and the like.

  The total amount of the solvent (water alone or a mixture of water and a water-soluble organic solvent) contained in the ink according to the present invention is preferably 50% by mass or more and 98% by mass or less, more preferably 80% by mass or more and 98% by mass. A mass% or less is more preferable. Furthermore, it is preferable that water is contained in an amount of 50% by mass to 80% by mass with respect to the total amount of ink.

  Examples of organic solvents having a vapor pressure at 25 ° C. of 0.01 mmHg (1.33 Pa) or higher include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, Examples include diethylene glycol monomethyl ether, propylene glycol, tripropylene glycol monomethyl ether, and dimethyl sulfoxide.

  Next, other components and characteristic values of the ink according to the present invention will be described.

[High molecular compound having a plurality of side chains in the main chain and capable of crosslinking between side chains by irradiation with active energy rays]
The ink according to the present invention includes a polymer compound having a plurality of side chains in the main chain and capable of crosslinking between side chains by irradiation with active energy rays (also referred to as an active energy ray-crosslinkable polymer compound). It is preferable to contain.

  The polymer compound having a plurality of side chains in the main chain according to the present invention and capable of crosslinking between the side chains by irradiating with active energy rays is a saponified product of polyvinyl acetate, polyvinyl acetal, polyethylene oxide, With respect to at least one resin selected from the group consisting of polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or derivatives of these resins, and copolymers thereof. A chain in which a modifying group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, or a photodepolymerization type is introduced. Photopolymerizable crosslinkable groups are desirable from the viewpoints of sensitivity and performance of the generated image.

  In the main chain, a saponified product of polyvinyl acetate is preferable from the viewpoint of ease of introduction of side chains and handling, and the degree of polymerization is preferably 200 or more and 4000 or less, and more preferably 200 or more and 2000 or less from the viewpoint of handling. preferable. The modification rate of the side chain with respect to the main chain is preferably 0.3 mol% or more and 4 mol% or less, but more preferably 0.8 mol% or more and 4 mol% or less from the viewpoint of reactivity. If the modification rate of the side chain with respect to the main chain is less than 0.3 mol%, the crosslinkability is insufficient and the effect of the present invention is reduced. If it exceeds 4 mol%, the crosslink density increases and the film becomes hard and brittle. Will fall.

  As the photodimerization-type modifying group, those in which a diazo group, a cinnamoyl group, a stilbazonium group, a stilquinolium group or the like is introduced are preferable. For example, a photosensitive resin described in JP-A-60-129742 (Composition).

  The photosensitive resin described in JP-A-60-129742 is a compound represented by the following general formula (1) in which a stilbazonium group is introduced into a polyvinyl alcohol structure.

In the general formula (1), R ₁ represents an alkyl group having 1 to 4 carbon atoms, and A ⁻ represents a counter anion.

  The photosensitive resin described in JP-A-56-67309 includes a 2-azido-5-nitrophenylcarbonyloxyethylene structure represented by the following general formula (2) in the polyvinyl alcohol structure, or the following general formula. This is a resin composition represented by (3) and having a 4-azido-3-nitrophenylcarbonyloxyethylene structure.

  Further, a modifying group represented by the following general formula (4) is also preferably used.

  In the general formula (4), R represents an alkylene group or an aromatic ring. A benzene ring is preferred.

  As the photopolymerization type modifying group, for example, a resin represented by the following general formula (5) shown in JP-A Nos. 2000-181062 and 2004-189841 is preferable from the viewpoint of reactivity.

In the general formula (5), R ₂ represents a methyl group or a hydrogen atom, n represents 1 or 2, X represents — (CH ₂ ) _m —COO— or —O—, and Y represents an aromatic ring. Or a single bond hand is represented, m represents the integer of 0-6.

  Moreover, it is also preferable to use the photopolymerization type | mold modified group represented by following General formula (6) described in Unexamined-Japanese-Patent No. 2004-161942 for a conventionally well-known water-soluble resin.

In the above general formula (6), R ₃ represents a methyl group or a hydrogen atom, and R ₄ represents a linear or branched alkylene group having 2 to 10 carbon atoms.

  Such an active energy ray cross-linking resin is preferably contained in an amount of 0.8% by mass to 5.0% by mass with respect to the total mass of the ink. The presence of 0.8% by mass or more improves cross-linking efficiency, and beading and color bleeding are more preferable due to a rapid increase in ink viscosity after cross-linking. In the case of 5.0% by mass or less, it is difficult to adversely affect the physical properties of the ink and the state in the ink head, which is preferable from the viewpoints of light emission properties and ink storage stability.

  In the active energy ray cross-linking polymer compound according to the present invention, the main chain having a certain degree of polymerization is cross-linked through a cross-linking bond between the side chains, and therefore through a general chain reaction. The effect of increasing the molecular weight per photon is remarkably large for the active energy ray-curable resin that polymerizes. On the other hand, in the conventionally known active energy ray curable resins, the number of crosslinking points cannot be controlled, so the physical properties of the cured film cannot be controlled, and the film tends to be hard and brittle.

  In the resin used in the present invention, the number of crosslinking points can be completely controlled by the length of the main chain and the amount of side chains introduced, and the physical properties of the ink film can be controlled according to the purpose.

  Furthermore, in the conventionally known active energy ray-curable ink, almost all of the ink other than the colorant is curable, so that the dots after curing increase the thickness of the plate and generate dot gain. Thus, in the printing plate preparation method using ink using the resin used in the present invention, a small amount of resin is added, and since there are many dry components, the dots do not rise unnecessarily after curing, and the printing finish is good. A plate can be formed.

[Photopolymerization initiator, sensitizer]
In this invention, it is preferable to add a photoinitiator and a sensitizer with the active energy ray crosslinkable high molecular compound which concerns on this invention. These compounds may be dissolved or dispersed in a solvent, or may be chemically bonded to the active energy ray crosslinkable polymer compound.

  There is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A conventionally well-known thing can be used.

  Although there is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A water-soluble thing is preferable from a viewpoint of mixability and reaction efficiency. In particular, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK), thioxanthone ammonium salt (QTX), and benzophenone ammonium salt (ABQ) are preferable from the viewpoint of miscibility with an aqueous solvent.

  Furthermore, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (n = 1, HMPK) represented by the following general formula (7) from the viewpoint of compatibility with the resin, The ethylene oxide adduct (n = 2 to 5) is more preferable.

  In the formula, n represents an integer of 1 to 5.

  Other examples include benzophenones such as benzophenone, hydroxybenzophenone, bis-N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone. Thioxanthones such as thioxatone, 2,4-diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and isopropoxychlorothioxanthone. Anthraquinones such as ethyl anthraquinone, benzanthraquinone, aminoanthraquinone and chloroanthraquinone. Acetophenones. Benzoin ethers such as benzoin methyl ether. 2,4,6-trihalomethyltriazines, 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di ( m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-phenylimidazole dimer, 2- (P-methoxyphenyl) -4,5-diphenylimidazole dimer, 2-di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5- Diphenylimidazole dimer 2,4,5-triarylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2-dimethyl Mino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-hydroxy-2-methyl-1-phenyl -Propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, phenanthrenequinone, 9,10-phenanthrenequinone, Benzoins such as methylbenzoin and ethylbenzoin, 9-phenylacridine, acridine derivatives such as 1,7-bis (9,9'-acridinyl) heptane, bisacylphosphine oxide, and mixtures thereof are preferably used. May be used alone or in combination.

  In addition to these photopolymerization initiators, accelerators and the like can also be added. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like. These photopolymerization initiators are preferably grafted to the side chain with respect to the main chain.

[Active energy rays, irradiation method]
In the ink jet plate making method of the present invention, in the ink using the active energy ray crosslinkable polymer compound, after applying the ink on the printing plate material, the active image is irradiated to cure the formed image, and then It is preferable to evaporate and dry the ink solvent. Moreover, in the ink which does not contain an active energy ray crosslinkable polymer compound, it is preferable that after applying ink on a printing plate material, the active energy ray is irradiated to evaporate and dry the ink solvent.

  Examples of the active energy rays here include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. However, they are dangerous to the human body, easy to handle, and can be used industrially. Widely used electron beams and ultraviolet rays are preferable.

  When using an electron beam, the amount of the electron beam to be irradiated is preferably in the range of 0.1 to 30 Mrad. If it is less than 0.1 Mrad, a sufficient irradiation effect cannot be obtained, and if it exceeds 30 Mrad, the support or the like may be deteriorated.

  When ultraviolet rays are used, the light source is, for example, a low pressure, medium pressure, high pressure mercury lamp, metal halide lamp, xenon lamp having a light emission wavelength in the ultraviolet region, cold cathode tube, hot cathode having an operating pressure of 0.1 kPa to 1 MPa. A conventionally well-known thing, such as a pipe | tube and LED, is used.

(Light irradiation conditions after ink landing)
As the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated within 0.001 to 1.0 seconds after ink landing, and more preferably 0.001 to 0.5 seconds.

  In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

(Installation of lamp)
As a method for irradiating active energy rays, a basic method is disclosed in Japanese Patent Application Laid-Open No. 60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing.

  Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of applying a collimated light source to a mirror surface provided on the side of the head unit and irradiating the recording unit with UV light is disclosed. Yes. Any of these irradiation methods can be used in the image forming method of the present invention.

  Also preferred is a method in which the irradiation of active energy rays is divided into two stages, the active energy rays are first irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and further the active energy rays are irradiated. It is one of.

(Solid dispersion)
In the inkjet plate making method of the present invention, it is preferable that the plate-forming ink contains a solid dispersion dispersed using a polymer dispersant.

  Examples of the solid material include colorants such as inorganic pigments and organic pigments, and filler particles such as inorganic fine particles and organic fine particles.

  Polymer dispersants that can be applied to the dispersion of solid materials are used with particles such as the above pigments, and have a high affinity with hydrophobic pigments that are used for particle refinement and stabilization, and hydrophilic properties. It is a polymer compound that has a portion with high affinity for water in the molecule. For example, from two or more monomers selected from styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives And a block copolymer, a random copolymer and salts thereof, polyoxyalkylene, polyoxyalkylene alkyl ether, and the like. Commercially available dispersants include BYK-160, BYK-162, BYK-164, BYK-182, EFKA-401, and EFKA- manufactured by EFKA. 402 ”,“ Solspers 24000 ”manufactured by Zeneca Corporation, and the like, but are not limited thereto.

(Coloring material)
The ink used in the ink jet plate making method of the present invention may be a clear ink that does not contain a colorant, but it is preferable to contain a colorant for the purpose of easily identifying the pattern drawn on the printing plate.

  The content of the colorant may be smaller than that of the inkjet ink used for general image formation, and is preferably 0.1% by mass or more and 3% by mass or less with respect to the total amount of the ink. Moreover, as a kind of coloring material, any of a dye and a pigment may be sufficient.

(dye)
There is no restriction | limiting in particular as dye which can be used by this invention, Water-soluble dyes, such as an acid dye, a direct dye, and a reactive dye, a disperse dye, etc. are mentioned.

  Hereinafter, specific examples of the dye applicable to the ink according to the present invention will be listed, but the present invention is not limited only to these exemplified dyes.

<Water-soluble dye>
Examples of water-soluble dyes that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, and diphenylmethane dyes.

  Furthermore, as the dye, a compound represented by the following general formula (8) or a compound represented by the general formula (9) can also be used.

In the general formula (8), R ¹ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or a phenylcarbonyl group. R ² may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom. R ³ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom or a substitutable substituent and is preferably a hydrogen atom or an aryloxy group. R ⁵ may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a sulfonic acid group. n1 represents an integer of 1 to 4, and m1 represents an integer of 1 to 5.

In the general formula (9), X ¹ represents a phenyl group or a naphthyl group, may be substituted with a substitutable substituent, and is preferably substituted with a sulfonic acid group or a carboxyl group. Y ¹ represents a hydrogen ion, a sodium ion, a potassium ion, a lithium ion, an ammonium ion or an alkylammonium ion. R ⁶ may be different and represents a hydrogen atom or a substituent that can be substituted on the naphthalene ring. q1 represents 1 or 2. p1 represents an integer of 1 to 4. However, q1 + p1 = 5. Z ¹ represents a substitutable substituent, represents a carbonyl group, a sulfonyl group or a group represented by the following general formula (10), and particularly preferably a group represented by the following general formula (10).

In the general formula (10), W ₁ and W ₂ each independently represent a halogen atom, amino group, hydroxyl group, alkylamino group or arylamino group, preferably a halogen atom, hydroxyl group or alkylamino group.

<Disperse dye>
As the disperse dye, various disperse dyes such as an azo disperse dye, a quinone disperse dye, an anthraquinone disperse dye, and a quinophthalone disperse dye can be used.

(Pigment)
As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation, and any of water-dispersible pigments, solvent-dispersible pigments, and the like can be used, for example, organic pigments such as insoluble pigments and lake pigments, An inorganic pigment such as carbon black can be preferably used. This pigment is present in a state of being dispersed in the ink, and this dispersion method may be any of self dispersion, dispersion using a surfactant, polymer dispersion, and microcapsule dispersion.

  The insoluble pigment is not particularly limited. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 202, C.I. I. Pigment red 222, C.I. I. Pigment violet 19 and the like.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  The average particle size of the dispersed state of the pigment contained in the ink according to the present invention is preferably 50 nm or more and less than 200 nm.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and often used.

  The pigment used in the ink according to the present invention is preferably used after being dispersed by a disperser together with a dispersant and other additives necessary for various desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. In particular, the particle size distribution of the ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the diameter of the beads is preferably 0.3 mm to 3 mm.

  In dispersing the pigment contained in the ink according to the present invention, a surfactant or the polymer dispersant can be used alone or in combination as the dispersant.

[Surfactant]
The ink according to the present invention may contain a surfactant. Surfactants preferably applied to the ink according to the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, Anionic surfactants such as fatty acid salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, glycerin esters, Activators such as sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

  These surfactants can also be used as pigment dispersants, and anionic and nonionic surfactants can be particularly preferably used.

[Various additives]
In the present invention, other conventionally known additives can be contained. For example, fluorescent brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffers, antioxidants, surfaces These are tension modifiers, non-resistance modifiers, rust inhibitors, inorganic pigments, and the like.

[Ink physical properties]
The ink according to the present invention has a preferable range of physical properties of the ink in order to stably produce a high-definition printing plate by an ink jet method.

  The viscosity of the ink is preferably 1 mPa · s or more and 15 mPa · s or less, and particularly preferably 2 mPa · s or more and 8 mPa · s or less. When the viscosity is less than 1 mPa · s, stable injection cannot be performed, and when the viscosity exceeds 15 mPa · s, satellites are easily generated, which causes a problem as a printing plate. Further, it becomes impossible to eject ink at a fast repetition period, and the production speed is lowered.

  The surface tension of the ink is preferably from 25 mN / m to 50 mN / m, particularly preferably from 30 mN / m to 45 mN / m. If it is less than 25 mN / m, the wetted spread of the dots that have landed on the printing plate material is large, and the resolution is lowered. On the other hand, if it exceeds 50 mN / m, bubbles are not easily removed from the ink jet recording head, and the ejection stability is poor.

[Ink preparation method]
The ink according to the present invention can be produced by a conventionally known method, but it is preferable to perform filtration in the production process. As a filtration method, for example, a metal mesh filter is used, but it is also preferable to perform filtration with a resin volume filtration filter such as polypropylene in combination with this.

  Further, the ink according to the present invention is preferably subjected to deaeration treatment. Examples of the degassing method include a method of degassing by stirring in a vacuum chamber, a method of sealing and degassing after heating the ink, and a method of using a degassing module using a hollow fiber. A method using a deaeration module is particularly preferred.

[Printing plate]
The printing plate material used in the inkjet plate making method of the present invention preferably has a hydrophilic surface. As a support used for the printing plate material, a conventionally known plate material used for a lithographic printing plate can be used without limitation. For example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, etc.), metal plate (for example, aluminum, etc.), plastic film (for example, cellulose triacetate, cellulose butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene naphthalate, etc.) ).

  Particularly preferred supports include paper, polyester film, polyethylene terephthalate or aluminum plate.

  In order to impart hydrophilicity to these supports, chemical treatment such as physical treatment such as plasma treatment or corona discharge, coating with hydrophilic resin, or immersion in a surfactant solution is used alone or in combination. Is preferably applied. Furthermore, it is preferable that the surface is roughened so that dampening water can be easily applied. As a roughening method, there is a method in which organic or inorganic fine particles are attached to the surface by coating or the like, and micro unevenness is imparted by this network structure. Other preferred examples include those in which a water-resistant hydrophilic layer is provided as a surface layer on an arbitrary support. Examples of such a surface layer include a layer composed of an inorganic pigment and a binder described in U.S. Pat. No. 3,055,295 and JP-A-56-13168, and a hydrophilic layer described in JP-A-9-80744. And a sol-gel film made of titanium oxide, polyvinyl alcohol and silicic acid described in JP-A-8-507727.

  When an aluminum plate widely used as a printing plate is used as a support, roughening treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluorinated zirconate, phosphate, or the like, or an anode It is preferable that surface treatment such as oxidation treatment is performed.

  The surface of the aluminum plate can be roughened by various methods. For example, it is performed by a method of mechanically roughening, a method of electrochemically dissolving and roughening the surface, and a method of selectively dissolving the surface chemically. As the mechanical method, known methods such as a ball polishing method, a brush polishing method, a blast polishing method, a buffing method, and a polishing method can be used. In addition, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in an electrolytic solution such as hydrochloric acid or nitric acid. Further, prior to roughening the aluminum plate, for example, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution, or the like is performed in order to remove rolling oil on the surface, if desired.

  Further, after performing these treatments, a water-soluble resin such as polyvinyl phosphonic acid, a polymer and copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt (for example, zinc borate) or Those having a primer such as a yellow dye or an amine salt are also suitable.

  The ink jet plate making method of the present invention is characterized in that the printing plate material is preheated when an image is formed on the printing plate material using the plate forming ink.

  As a method for heating the printing plate material, heating is performed to a desired temperature using a heat plate, a heating roller, a radiant heat source, hot air, or the like from the front surface or the back surface of the printing plate material.

  The temperature for heating the printing plate is preferably in the range of 30 to 80 degrees.

  In the present invention, the printing plate material is heated to form an image even after the plate is formed using the plate forming ink containing the solid dispersion dispersed using the polymer dispersant. As the heating means, the same method as described above can be appropriately selected and used. Similarly, the temperature for heating the printing plate material is preferably in the range of 30 to 80 degrees.

[Inkjet recording method]
In the ink jet plate making method of the present invention, ink is ejected as droplets from an ink jet recording head based on image information by an ink jet printer loaded with the plate forming ink according to the present invention and adhered to a printing plate material. When an ink containing an energy ray crosslinkable polymer compound is used, a printing plate for printing is formed through curing with active energy rays and evaporation drying of the ink solvent.

  The ink jet recording head used in the ink jet plate making method of the present invention may be an on-demand system or a continuous system. As the discharge method, an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

  The amount of ink droplets ejected from the head is preferably 0.5 picoliters or more and 7 picoliters or less, and particularly preferably 0.8 picoliters or more and 4 picoliters or less. If it is less than 0.5 picoliter, the droplets ejected from the head are likely to decrease in speed during flight due to air resistance, and the landing positions are likely to vary. In addition, when a suitable amount of ink liquid exceeds 7 picoliters, one dot size increases, and naturally the resolution as a printing plate decreases.

  Further, it is possible to devise ejection and eject a plurality of appropriate amounts of liquid from one head, or to eject after a plurality of droplets are continuously ejected and united during flight.

  The ink jet printer applicable to the present invention may be of any type, but it is preferable to use a flat bed type or a drum type when producing a high-quality printing plate. Also preferred is a method in which the printer of the present invention is incorporated in a printing press and plate-making is performed on the printing press.

[Characteristic value of forming plate: receding contact angle]
In the ink jet plate making method of the present invention, the resin film surface formed on the printing plate material using the plate forming ink preferably has a receding contact angle with respect to water of 40 ° or more, more preferably 50 °. It is above, More preferably, it is 70 degrees or more.

  In general, the contact angle θ means an angle formed by a stationary droplet with a solid surface, and is also called a static contact angle θ (also referred to as an equilibrium contact angle). When the ink droplet for printing starts moving on the substrate, the static contact angle θ disappears, and the advancing contact angle θa and the receding contact angle θr appear, and these contact angles are called dynamic contact angles. Yes. The magnitude of the surface tension acting on the ink droplet for printing is σ cos θa in the direction in which the ink droplet is advanced, and σ cos θr in the direction in which the movement of the ink droplet is prevented. Since the advancing contact angle θa is a contact angle with respect to the substrate surface that has not been wetted with ink droplets yet, and the receding contact angle θr is a contact angle with respect to the substrate surface that has already been wetted with liquid, θa> θr is always established. To do. When an external force acts on the ink droplet and starts moving, and θa and θr appear, the force of σ cos θr−σ cos θa acts on the droplet in a direction that prevents the movement of the droplet. It will be a force to prevent.

  The measurement of the dynamic contact angle according to the present invention is performed using, for example, a contact angle meter CA-X manufactured by Kyowa Interface Science Co., Ltd., with an attached macro syringe, initial droplet volume = 15 μl, suction speed = 5 μl / sec. The receding contact angle θr can be obtained by measuring the contact angle when pure water is reduced on the surface of the resin film formed on the printing plate material under the above conditions and using pure water as a test solution. .

  Further, the receding contact angle will be specifically described with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a method for measuring a receding contact angle according to the present invention.

  The method for measuring the dynamic contact angle is roughly classified into a hanging plate method and a droplet method. The suspended flat plate method is a method in which a solid flat plate is vertically immersed in a liquid stored in a container, and the Wilhelmy plate method (Wilhelmy Plate method) and the like belong to the suspended flat plate method. In the droplet method, an appropriate amount of droplets is applied to the horizontal surface of a solid substrate, and the angle formed between the substrate and the droplets is measured. The droplet method has advantages such as a smaller amount of liquid sample and less restrictions on the shape of the solid substrate, and is preferable for measuring the receding contact angle according to the present invention.

  In the expansion / contraction method of the droplet method, the advancing contact angle θa is set to a constant flow rate of liquid 2 (pure water in the present invention) from the tip of the glass capillary 3 to the solid substrate 1 as shown in FIG. The advancing contact angle θa can be measured by extruding the use) and measuring the contact angle while forming the expanding microdroplet 4.

  FIG. 1B is a diagram for explaining the receding contact angle θr, and the microdroplet 4 on the solid substrate 1 is contracted while being drawn from the tip of the glass capillary 3 at a constant flow rate, and the contact angle is measured. Thus, the receding contact angle θr is measured. Here, a resin film formed on a printing plate material is used for the solid substrate 1.

When the shape of the microdroplet is a shape that forms a part of a sphere, the receding contact angle θr is determined from the contact surface diameter Lr and the height Hr of the microdroplet,
It is calculated | required by (theta) r = 2tan < ^-1 > 2Hr / Lr.

  Here, the receding contact angle θr is determined by the droplet method, particularly the expansion / contraction method, but may be measured by other methods.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Synthesis of polymer compounds >>
56 g of glycidyl methacrylate, 48 g of p-hydroxybenzaldehyde, 2 g of pyridine, and 1 g of N-nitroso-phenylhydroxyamine ammonium salt were put in a reaction vessel and stirred in a hot water bath at 80 ° C. for 8 hours.

  Next, 45 g of saponified polyvinyl acetate having a polymerization degree of 300 and a saponification rate of 88% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid and p- (3-methacryloxy-) obtained by the above reaction were added to this solution. 2-hydroxypropyloxy) benzaldehyde was added to polyvinyl alcohol so that the modification rate was 3 mol%, and the mixture was stirred at 90 ° C. for 6 hours. After cooling the obtained solution to room temperature, 30 g of basic ion exchange resin was added and stirred for 1 hour. Thereafter, the ion exchange resin is filtered, and Irgacure 2959 (manufactured by Ciba Japan Co., Ltd.) is mixed as a photopolymerization initiator at a ratio of 0.1 g with respect to 100 g of a 15% aqueous solution, and then diluted with ion exchange water. As a result, a 10% aqueous solution of polymer compound 1 was obtained.

<< Preparation of pigment dispersion (solid dispersion) >>
[Preparation of pigment dispersion 1]
Carbon black (MA-100, manufactured by Mitsubishi Chemical Corporation) 20 parts Ethylene glycol 30 parts Polymer dispersant: Joncrill 60 (solid content 34%, manufactured by BASF) 29.4 parts Ion-exchanged water 20.6 parts Each of the above ratios The components were mixed and dispersed using a horizontal bead mill (System Zeta Mini manufactured by Ashizawa Co., Ltd.) filled with zirconia beads having a diameter of 0.5 mm at a volume ratio of 60%, and then the zirconia beads were removed to obtain a pigment dispersion 1. .

  The ratio of the polymer dispersant to the pigment (carbon black) in the pigment dispersion 1 is 50% by mass.

[Preparation of pigment dispersion 2]
Carbon black (Mitsubishi Chemical Corporation MA-100) 20 parts Ethylene glycol 30 parts Ion-exchanged water 50 parts Each of the above components is mixed, and a horizontal bead mill filled with 60% by volume of 0.5 mm diameter zirconia beads ( The mixture was dispersed using Ashizawa Co., Ltd. System Zetamini, and then the zirconia beads were removed to obtain a pigment dispersion 2 containing no polymer dispersant.

<< Preparation of image forming ink >>
[Preparation of Ink 1]
Pigment dispersion 1 6.0% by mass
Polymer compound 1 2.0 mass% as solid content concentration
Resin fine particles: Joncrill 631 (acid value: 25 mgKOH / g, manufactured by BASF)
The solid content concentration is 5.0% by mass.
40% by mass of ethylene glycol
Ion exchange water was added to each of the above additives to make the total amount 100% by mass and stirred and mixed. Next, filtration with a # 3500 mesh metal filter and deaeration with a hollow fiber module were performed to prepare ink 1.

[Preparation of inks 2 to 10]
In the preparation of the ink 1, the presence / absence and addition amount (solid content) of the polymer compound, the type of resin fine particles, and the type of the pigment dispersion were changed in the same manner as described in Table 1, Inks 2 to 10 were prepared.

  In addition, the detail of each additive described with the abbreviation in Table 1 is as follows.

<Resin fine particles>
J631: Johncrill 631 (polystyrene-acrylic resin fine particles, BASF acid value: 25 mgKOH / g)
PDX-7145: Joncrill PDX-7145 (polystyrene-acrylic resin fine particles BASF Corporation acid value: 32 mgKOH / g)
SF110: Superflex 110 (Polyurethane resin fine particles, manufactured by Daiichi Kogyo Co., Ltd. 18mgKOH / g)
SF300: Superflex 110 (Polyurethane resin fine particles, manufactured by Daiichi Kogyo Co., Ltd. 4 mgKOH / g)
<< Preparation of printing plate making >>
[Preparation of printing plate making 1]
(Inkjet printer)
The ink jet printer 10 shown in FIG. 2 was used. The inkjet printer 10 has one piezo inkjet head 15 on the carriage 14 having a nozzle diameter of 20 μm, a nozzle number of 512, and a nozzle resolution of 300 dpi (dpi in the present invention represents the number of dots per 2.54 cm). The inkjet printer is equipped with an active energy ray irradiation unit 16 on both sides of the inkjet head 15 and an ultraviolet irradiation light source 17 is provided inside. An ultraviolet shielding plate 18 prevents the ultraviolet rays emitted from the ultraviolet irradiation light source 17 from affecting the nozzle portion 19 of the inkjet head 15.

(Preparation of printing plate making)
An ink jet head loaded with ink liquid number 6 prepared above after heating a grained aluminum base material, which is a printing plate 12 held on a platen 11, to 70 ° C. by a flat panel heater 13 disposed on the back surface Images were formed from 15 nozzle portions 19 with an ink droplet amount of 1 pl and a resolution of 1400 dpi × 1400 dpi. As an evaluation image, a solid image of 10 cm × 10 cm was produced on the entire surface.

  The ink was cured under the condition of 120 W / cm from an ultraviolet irradiation light source 17 (metal halide lamp MAL 400NL power supply power 3 kW · hr) built in an active energy ray irradiation unit 16 installed on both sides of the carriage 14. . Evaluation was made under two conditions of 400 mm / sec and 800 mm / sec as the moving speed of the carriage 14.

  Since each ink has a different viscosity, the voltage applied to the piezo element of the ink jet printer was adjusted so that the ink droplet amount of each ink was 1 pl.

  After the formation of the formed image was completed, the printing plate 12 was moved in the direction of arrow B shown in FIG. 2, and heat treatment was performed in the post-heating process. Inside the post-heating step 21, a hot air heater 22 is installed, and hot air of 70 ° C. is blown on the surface of the printing plate material 12 for 2 minutes to evaporate and dry the ink solvent. Produced.

[Preparation of printing plate making 2-17]
In the preparation of the printing plate making plate 1, the types of ink liquid, the presence or absence and heating temperature of the printing plate during image formation, the presence or absence of ultraviolet irradiation, and the presence or absence of post-heating process treatment are combined in the combinations shown in Table 1. Printing plate making 2-17 was produced similarly except having changed.

<Evaluation of printing plate making>
[Measurement of receding contact angle of printing plate making]
About the produced printing plate plate-making 13-17, Kyowa Interface Science Co., Ltd. contact angle meter CA-X type was used, and the method shown to b) of FIG. On the surface of the solid image formed on the printing plate under the condition of suction speed = 5 μl / sec, the contact angle when the water droplet is reduced was measured to obtain the receding contact angle θr.

[Evaluation of printability of printing plate making]
Each of the produced printing plate making plates was mounted on a printing machine, and 500 sheets were printed on coated paper (made by Hokuetsu Paper) using printing ink.

(Evaluation of liquid resistance)
About the solid image part of the printing plate making sample produced by the above method, the presence or absence of mottle was visually observed before printing, and the resistance to liquid leakage was evaluated according to the following criteria.

◎: No mottle is observed at all ○: Mottle is slightly observed but is of good quality △: Some weak mottle is observed, but is in a practically acceptable range ×: Occurrence of slightly strong mottle XX: Strong mottle is recognized on the entire surface, and the quality is not practical.
The density of the solid image portion printed on the ₅₀₀ sheets was measured, and the number of printed sheets starting to obtain a density of 98% or more with respect to the density D ₅₀₀ of the 500th sheet was measured. . The smaller the numerical value, the faster the final printed density D ₅₀₀ is obtained with the number of printed sheets, and the better the inking property.

  The results obtained as described above are shown in Table 1.

  As is apparent from the results shown in Table 1, it can be seen that the printing plate plate produced by the ink jet plate making method of the present invention is excellent in liquid-side resistance and inking property when producing the printing plate plate.

  In addition, it can be seen that by setting the liquid physical properties of the ink used at the time of making the printing plate to be 40 ° or more of the receding contact angle, the effects excellent in both the liquid-side resistance and the inking property are exhibited.

It is the schematic which shows an example of the measuring method of receding contact angle which concerns on this invention. In the Example, it is the schematic of the inkjet printer used for printing plate preparation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid substrate 2, 5 Liquid 3 Glass capillary 4 Micro droplet 10 Inkjet printer 11 Platen 12 Printing plate material 13 Flat panel heater 14 Carriage 15 Inkjet head 16 Active energy ray irradiation part 17 Ultraviolet irradiation light source 18 Ultraviolet shielding plate 19 Nozzle part 20 Ink droplet 21 Post-heating step 22 Hot air heater

Claims (5)

In an ink-jet plate making method for forming an image by adhering a plate-forming ink containing at least water, a water-soluble organic solvent and resin fine particles onto a heated printing plate material using an ink-jet method, the plate-forming ink An ink plate making method, wherein the acid value of the resin fine particles contained in is 30 mgKOH / g or less. 2. The inkjet plate making according to claim 1, wherein the plate-forming ink contains a solid dispersion dispersed using a polymer dispersant, and the printing plate material is heated to form an image after printing. Method. The inkjet plate-making method according to claim 1 or 2, wherein the resin film surface formed on the printing plate material using the plate-forming ink has a receding contact angle with respect to water of 40 ° or more. The polymer contains a polymer compound having a plurality of side chains in the main chain and capable of crosslinking between side chains by irradiating with active energy rays. The main chain of the molecular compound is a saponified product of polyvinyl acetate, having a saponification degree of 77% or more and 99% or less, and a polymerization degree of 200 or more and 4000 or less. 2. The ink jet plate making method according to item 1. After the plate forming ink is deposited on the printing plate material by the inkjet method, the plate forming ink is irradiated with active energy rays, and the ink solvent is evaporated and dried to form an image and print. A printing plate is produced, The inkjet plate-making method of any one of Claims 1-4 characterized by the above-mentioned.

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