Aqueous developer for flexographic printing plate, aqueous developing concentrate for flexographic printing plate, and method for producing flexographic printing plate

Abstract

To provide an aqueous developer for a flexographic printing plate, which has excellent concentration suitability and good storage stability in a case of being made into a concentrated solution, an aqueous developing concentrated solution for a flexographic printing plate, and a manufacturing method for a flexographic printing plate using these.SOLUTION: An aqueous developer for a flexographic printing plate of the present invention includes an anionic surfactant, a nonionic surfactant, and water, in which the anionic surfactant is a compound represented by Formula (1): R1-X1 (1). In Formula (1), R1 represents an alkyl group having 3 to 20 carbon atoms, an alkenyl group having 3 to 20 carbon atoms, or an alkynyl group having 3 to 20 carbon atoms, which may have a substituent, and X1 represents a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous developer for flexographic printing plates, an aqueous developer concentrate for flexographic printing plates, and a method for producing a flexographic printing plate using these.

Background Art

[0002] In recent years, there has been a movement in various industries to reduce the use of organic solvents from the viewpoints of improving the working environment and conserving the global environment. In the plate-making process of photosensitive flexographic printing plates used in printing, the use of water-developable photosensitive resin plates is increasing.

[0003] For example, Patent Document 1 describes "a developer composition for printing plates containing (a) an alkali metal salt of a saturated fatty acid having 12 to 18 carbon atoms and (b) an alkali metal salt of an unsaturated fatty acid having 12 to 18 carbon atoms in a weight ratio of (a):(b) = 20:80 to 80:20." ([Claim 1]).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of the present invention studied the aspect of making an aqueous developer described in Patent Document 1, etc. into a concentrate from the viewpoint of reducing the volume during storage and transportation. However, depending on the type of surfactant contained in the aqueous developer, the solubility or dispersibility of the surfactant may decrease when made into a concentrate, resulting in poor concentration suitability. Also, even if the solubility of the surfactant is good when made into a concentrate, precipitation of the surfactant may occur over time, resulting in poor storage stability.

[0006] Therefore, an object of the present invention is to provide an aqueous developer for flexographic printing plates, an aqueous developing concentrate for flexographic printing plates, and a method for manufacturing a flexographic printing plate using these, which are excellent in concentration suitability and have good storage stability when used as a concentrate.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above problems, the present inventors have found that an aqueous developer containing a nonionic surfactant together with a predetermined anionic surfactant is excellent in concentration suitability and has good storage stability when used as a concentrate, and have completed the present invention. That is, the present inventors have found that the above problems can be achieved by the following configuration.

[0008] [1] An aqueous developer for a flexographic printing plate, comprising an anionic surfactant, a nonionic surfactant, and water, wherein the anionic surfactant is a compound represented by the following formula (1): an aqueous developer for a flexographic printing plate. R 1 -X 1 ···(1) Here, in the above formula (1), R 1 represents an alkyl group having 3 to 20 carbon atoms, an alkenyl group having 3 to 20 carbon atoms, or an alkynyl group having 3 to 20 carbon atoms, which may have a substituent. X 1 represents a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a sulfuric acid group or a salt thereof, or a phosphoric acid group or a salt thereof. [2] The aqueous developer for a flexographic printing plate according to [1], wherein the content of the anionic surfactant is 0.01 to 10% by mass, and the content of the nonionic surfactant is 0.01 to 10% by mass. [3] The aqueous developer for a flexographic printing plate according to [1] or [2], further containing an alkali agent. [4] The aqueous developer for a flexographic printing plate according to any one of [1] to [3], wherein the carbon number of R in the above formula (1) is 6 to 14. 1 [5] The aqueous developing solution for flexographic printing plates according to any one of [1] to [4], wherein the compound represented by the above formula (1) has an HLB value of 8 or less and is water-soluble. [6] The aqueous developing solution for flexographic printing plates according to any one of [1] to [5], wherein the nonionic surfactant is a compound represented by the following formula (2). [Chemical formula] Here, in the above formula (2), Ar represents an m-valent aromatic group, and m represents an integer from 1 to 8. X 2 represents a monovalent organic group, and p represents an integer from 0 to 3. However, p < m, and when p is 2 or 3, a plurality of X 2 may be the same as or different from each other. A represents an alkylene group having 2 to 4 carbon atoms, R 2 represents a hydrogen atom or an alkyl group, and n represents an integer from 1 to 100. When n is an integer from 2 to 100, a plurality of A may be the same as or different from each other. When m - p is an integer from 2 to 8, a plurality of A, n, and R 2 may all be the same as or different from each other.

[0009] [7] A method for manufacturing a flexographic printing plate having a non-image area and an image area, comprising: an exposure step of exposing the photosensitive layer of the flexographic printing plate original having a photosensitive layer in an image-like manner; a developing step of developing after the exposure step using the aqueous developing solution for flexographic printing plates according to any one of [1] to [6] to form a non-image area and an image area; a rinsing step of rinsing with water after the developing step. A method for manufacturing a flexographic printing plate.

[0010] [8] A concentrated solution of an aqueous developing solution for flexographic printing plates, comprising: a concentrated aqueous developing solution for flexographic printing plates containing an anionic surfactant, a nonionic surfactant, and water. [9] The aqueous developing concentrate for flexographic printing plates according to [8], wherein the content of the anionic surfactant is 0.02 to 40% by mass and the content of the nonionic surfactant is 0.02 to 40% by mass.

[10] The aqueous developing concentrate for flexographic printing plates according to [8] or [9], further containing an alkali agent.

[11] The aqueous developing concentrate for flexographic printing plates according to any one of [8] to

[10] , wherein the anionic surfactant is a compound represented by the following formula (1). R 1 -X 1 ···(1) Here, in the above formula (1), R 1 represents an alkyl group having 3 to 20 carbon atoms, an alkenyl group having 3 to 20 carbon atoms, or an alkynyl group having 3 to 20 carbon atoms, which may have a substituent. X 1 represents a carboxylic acid group or its salt, a sulfonic acid group or its salt, a sulfuric acid group or its salt, or a phosphoric acid group or its salt.

[12] The aqueous developing concentrate for flexographic printing plates according to

[11] , wherein the carbon number of R in the above formula (1) is 6 to 14. 1

[13] The aqueous developing concentrate for flexographic printing plates according to

[11] or

[12] , wherein the compound represented by the above formula (1) has an HLB value of 8 or less and is water-soluble.

[14] The aqueous developing concentrate for flexographic printing plates according to any one of [8] to

[13] , wherein the nonionic surfactant is a compound represented by the following formula (2).

Chemical formula

[0011]

[15] A method for manufacturing a flexographic printing plate having a non - image part and an image part, comprising an exposure step of exposing the photosensitive layer of the flexographic printing plate original having a photosensitive layer in an image - like manner, and after the exposure step, developing using a solution obtained by diluting the aqueous developing concentrate for flexographic printing plates described in any one of [8] to

[14] by 2 to 20 times to form a non - image part and an image part, and after the developing step, a rinsing step of rinsing with water. A method for manufacturing a flexographic printing plate.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide an aqueous developing solution for flexographic printing plates, an aqueous developing concentrate for flexographic printing plates, which are excellent in concentration suitability and have good storage stability when made into a concentrate, and a method for manufacturing a flexographic printing plate using these.

Modes for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as a lower limit value and an upper limit value. In addition, in this specification, each component may be used alone as one kind of substance corresponding to each component, or two or more kinds may be used in combination. Here, when two or more kinds of substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified.

[0014] [Aqueous developer for flexographic printing plate] The aqueous developer for a flexographic printing plate of the present invention (hereinafter also abbreviated as "the developer of the present invention") is an aqueous developer for a flexographic printing plate containing an anionic surfactant, a nonionic surfactant, and water. In addition, the anionic surfactant contained in the developer of the present invention is a compound represented by the following formula (1).

[0015] In the present invention, as described above, an aqueous developer containing a nonionic surfactant together with the anionic surfactant represented by the following formula (1) has excellent concentration suitability and good storage stability when made into a concentrated solution. Although the details are not clear, the present inventors presume as follows. First, as shown in Comparative Examples 1 to 4 described later, when no nonionic surfactant is blended and only an anionic surfactant is blended, it can be seen that the concentration suitability is poor. In addition, as shown in Comparative Example 5 described later, when no anionic surfactant is blended and only a nonionic surfactant is blended, it can be seen that the storage stability when made into a concentrated solution is poor. Therefore, in the present invention, by blending a nonionic surfactant together with the anionic surfactant represented by the following formula (1), due to the interaction between these surfactants, the dispersibility or solubility is improved compared to the case where each surfactant is blended alone, so that the concentration suitability is excellent and the storage stability when made into a concentrated solution is also good. Hereinafter, each component contained in the developer of the present invention will be described in detail.

[0016] 〔Anionic surfactant〕 The anionic surfactant contained in the developer of the present invention is a compound represented by the following formula (1). R 1 -X 1 (1)

[0017] In the above formula (1), R 1 represents an alkyl group having 3 to 20 carbon atoms, an alkenyl group having 3 to 20 carbon atoms, or an alkynyl group having 3 to 20 carbon atoms, each of which may have a substituent. In addition, in the above formula (1), X 1 represents a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

[0018] R in the above formula (1) 1 The alkyl group having 3 to 20 carbon atoms in one embodiment of the above may be any of linear, branched, and cyclic, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, a stearyl group, a cyclohexyl group, and a cyclooctyl group. R in the above formula (1) 1 The alkenyl group having 3 to 20 carbon atoms in one embodiment may be any of linear, branched, and cyclic, and specific examples thereof include a 1-propenyl group, a 1-butenyl group, a 1-methyl-1-propenyl group, a 1-hexenyl group, a 2-hexenyl group, a 3-hexenyl group, a 4-hexenyl group, a 5-hexenyl group, and a cyclohexenyl group. R in the above formula (1) 1 The alkynyl group having 3 to 20 carbon atoms in one embodiment may be linear, branched, or cyclic, and specific examples thereof include a 1-propynyl group, a 1-butynyl group, a 1-octynyl group, a 1-decynyl group, and a 1-octadecynyl group.

[0019] In addition, R in the above formula (1) 1As the substituent which may be possessed, a monovalent non-metal atomic group excluding a hydrogen atom is used. For example, a halogen atom (F, Cl, Br or I), a hydroxy group, an alkoxy group, an aryloxy group, an acyl group, an amide group, an ester group, an acyloxy group, a carboxy group, a carboxylic acid anion group, a sulfonic acid anion group and the like can be mentioned. Specific examples of the alkoxy group include those having preferably 1 to 40 carbon atoms, more preferably 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butyloxy group, a pentyloxy group, a hexyloxy group, a dodecyloxy group, a stearyloxy group, a methoxyethoxy group, a poly(ethyleneoxy) group, a poly(propyleneoxy) group and the like. Specific examples of the aryloxy group include those having 6 to 18 carbon atoms, such as a phenoxy group, a tolyloxy group, a xylyloxy group, a mesityloxy group, a cumenyloxy group, a methoxyphenyloxy group, an ethoxyphenyloxy group, a chlorophenyloxy group, a bromophenyloxy group, a naphthyloxy group and the like. Specific examples of the acyl group include those having 2 to 24 carbon atoms, such as an acetyl group, a propanoyl group, a butanoyl group, a benzoyl group, a naphthoyl group and the like. Specific examples of the amide group include those having 2 to 24 carbon atoms, such as an acetamide group, a propionic acid amide group, a dodecanoic acid amide group, a partimic acid amide group, a stearic acid amide group, a benzoic acid amide group, a naphthoic acid amide group and the like. Specific examples of the acyloxy group include those having 2 to 20 carbon atoms, such as an acetoxy group, a propanoyloxy group, a benzoyloxy group, a naphthoyloxy group and the like. Specific examples of the ester group include those having 1 to 24 carbon atoms, such as a methyl ester group, an ethyl ester group, a propyl ester group, a hexyl ester group, an octyl ester group, a dodecyl ester group, a stearyl ester group and the like. The substituent may be composed of a combination of two or more of the above substituents.

[0020] In the present invention, regarding the developer of the present invention, since the formation of a film formed on the liquid surface can be suppressed, R in the above formula (1) 1 preferably has 6 to 14 carbon atoms. Specifically, R in the above formula (1) 1 is more preferably an alkyl group having 6 to 14 carbon atoms, and in the development using the developer of the present invention, since the aggregation of development residues (dispersion) can be suppressed, it is even more preferably an alkyl group having 6 to 10 carbon atoms.

[0021] As described above, X in the above formula (1) 1 represents a carboxylic acid group (-COOH) or its salt, a sulfonic acid group (-SO3H) or its salt, a sulfuric acid group (-OSO3H) or its salt, or a phosphoric acid group (-OPO3H2) or its salt. Among them, it is preferably a carboxylic acid group or its salt, a sulfonic acid group or its salt, or a sulfuric acid group or its salt, and more preferably a carboxylic acid group or its salt. In addition, the salt such as a carboxylic acid group is preferably an alkali metal salt such as a sodium salt or a potassium salt.

[0022] In the present invention, regarding the developer of the present invention, since the formation of a film formed on the liquid surface can be suppressed, the compound represented by the above formula (1) preferably has an HLB value of 8 or less and is water-soluble. In addition, the compound represented by the above formula (1) preferably has an HLB value of 3 or more.

[0023] Here, the HLB (Hydrophile Lipophile Balance) value in the present invention means a value calculated by the following formula (HL) using the molecular weight of the compound represented by the above formula (1) as M and the molecular weight of X 1 in the above formula (1) as Mw. HLB value = 20 × Mw / M ··· (HL)

[0024] In the present invention, "being water-soluble" means that when the compound represented by the above formula (1) is dried at 105°C for 2 hours and then dissolved in 100 g of water at 40°C, no insoluble matter can be visually confirmed within 3 hours.

[0025] In the present invention, the content of the anionic surfactant is preferably 0.01 to 10% by mass, more preferably 0.1 to 2% by mass, based on the total mass of the developer of the present invention.

[0026] [Nonionic surfactant] The nonionic surfactant contained in the developer of the present invention is not particularly limited, and a conventionally known nonionic surfactant can be used. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylene glycerin fatty acid partial esters, polyoxyethylene diglycerins, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, polyoxyethylene alkyl phenyl ethers, polyoxyethylene-polyoxypropylene block copolymers, and the like.

[0027] In the present invention, since the storage stability as a concentrated solution becomes better and the aggregation of development residues (dispersions) can be suppressed in development using the developer of the present invention, the nonionic surfactant is preferably a compound represented by the following formula (2). [Chemical formula]

[0028] In the above formula (2), Ar represents an m-valent aromatic group, and m represents an integer from 1 to 8. Also, in the above formula (2), X 2 represents a monovalent organic group, and p represents an integer from 0 to 3. However, p < m, and when p is 2 or 3, the plurality of Xs 2 may be the same as or different from each other. Also, in the above formula (2), A represents an alkylene group having 2 to 4 carbon atoms, R 2 represents a hydrogen atom or an alkyl group, and n represents an integer from 1 to 100. When n is an integer from 2 to 100, the plurality of As may be the same as or different from each other. When m - p is an integer from 2 to 8, the plurality of As, ns, and Rs 2 may all be the same as or different from each other.

[0029] The aromatic group represented by Ar in the above formula (2) refers to a group containing an aromatic ring, and examples include an m-valent group having at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocyclic ring. Here, examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthroline ring, etc., and examples of the aromatic heterocyclic ring include a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, a benzothiazole ring, etc. Also, the valence number (m) of the aromatic group represented by Ar in the above formula (2) is an integer from 1 to 8, preferably an integer from 2 to 6, more preferably an integer from 2 to 4, and still more preferably 2 or 3. Among these, as Ar, a divalent benzene ring (i.e., a phenylene group) and a monovalent naphthalene ring (i.e., a naphthyl group) are preferred, and a phenylene group is more preferred.

[0030] X in the above formula (2) 2Examples of the monovalent organic group shown include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, etc., and these groups may further have substituents. Examples of the alkyl group include linear or branched alkyl groups having 1 to 18 carbon atoms, and specifically, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a tert-pentyl group, an n-hexyl group, etc. are mentioned. Examples of the cycloalkyl group include monocyclic or polycyclic cycloalkyl groups having 3 to 20 carbon atoms, and specifically, a cyclopentyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclohexyl group, a cyclohexylmethyl group, a cyclohexylethyl group, etc. are mentioned. Examples of the aryl group include aryl groups having 6 to 14 carbon atoms, and specifically, for example, a phenyl group, a methylphenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, etc. are mentioned. Examples of the aralkyl group include aralkyl groups having 7 to 20 carbon atoms, and specifically, a benzyl group, a phenethyl group, a 2-phenylethane-2-yl group, a naphthylmethyl group, etc. are mentioned. Examples of the alkenyl group include alkenyl groups having 3 to 20 carbon atoms, and specifically, a vinyl group, an allyl group, etc. are mentioned.

[0031] Among these organic groups, for the reason that the aggregation of the dispersion can be more suppressed, X in the above formula (2) 2 is preferably an aralkyl group, and more preferably a 2-phenylethane-2-yl group or a benzyl group. Note that the structures of the 2-phenylethane-2-yl group and the benzyl group are as shown in the following formulas (X-1) and (X-2), respectively. Regarding the structure shown by the following formula (X-1) (2-phenylethane-2-yl group), it is also referred to as "styrenated" or "styryl group".

Chemical formula

[0032] In the above formula (2), p represents an integer from 0 to 3, provided that p < m. In the development using the developer of the present invention, since the aggregation of development waste can be suppressed, p preferably represents an integer from 1 to 3, and more preferably represents 1 or 2.

[0033] In the above formula (2), A represents an alkylene group having 2 to 4 carbon atoms, preferably an alkylene group having 2 or 3 carbon atoms, and more preferably an ethylene group or an n-propylene group.

[0034] R in the above formula (2) 2 As the alkyl group represented by one embodiment, for example, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. Specifically, a methyl group, an ethyl group, a propyl group, and an n-butyl group can be mentioned. In addition, R in the above formula (2) 2 represents a hydrogen atom or an alkyl group, but in the development using the developer of the present invention, since the aggregation of development waste can be suppressed, a hydrogen atom is preferable.

[0035] In the above formula (2), n represents an integer from 1 to 100, but in the development using the developer of the present invention, since the aggregation of development waste can be suppressed, it is preferably an integer from 1 to 30, more preferably an integer from 5 to 20, and still more preferably an integer from 5 to 15.

[0036] Specific examples of the compound (nonionic surfactant) represented by the above formula (2) include, for example, polyoxyethylene styrenated phenyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tristyryl phenyl ether represented by the following formula (2-1), ammonium polyoxyethylene styrenated phenyl ether sulfate, polyoxyethylene polystyryl phenyl ether condensate, and other polyoxyalkylene polystyryl phenyl ethers; Polyoxyethylene dodecyl phenyl ether, polyoxyethylene phenyl ether, polyoxyethylene benzyl ether, polyoxyethylene β-naphthyl ether, polyoxyethylene bisphenol A ether, polyoxyethylene bisphenol F ether, polyoxyethylene cumyl phenyl ether, polyoxyethylene naphthyl ether, polyoxyethylene tribenzyl phenyl ether, polyoxyethylene aryl ether, polyoxyethylene polycyclic phenyl ether, polyoxyalkylene polycyclic phenyl ether; etc. can be mentioned.

Chemical formula

[0037] In the present invention, the content of the nonionic surfactant is preferably 0.01 to 10% by mass, more preferably 0.1 to 2% by mass, based on the total mass of the developer of the present invention.

[0038] 〔Water〕 The water contained in the developer of the present invention is not particularly limited, and any of ultrapure water such as purified water, distilled water, ion-exchanged water, pure water, and Milli-Q water can be used. Note that Milli-Q water is ultrapure water obtained by a Milli-Q water production apparatus, which is an ultrapure water production apparatus of Merck & Co., Ltd. The content of water contained in the developer of the present invention is preferably 80 to 99.99% by mass, more preferably 90 to 99.9% by mass, based on the total mass of the developer.

[0039] 〔Alkali agent〕 The developer of the present invention preferably contains an alkali agent because it has good developability. Examples of the alkali agent include alkali metal carbonates and alkali metal hydroxides. Here, specific examples of the alkali metal include sodium, potassium, and calcium. As for the alkali metal carbonate, specifically, for example, sodium carbonate, potassium carbonate and the like can be mentioned. Among them, sodium carbonate is preferable from the viewpoint of safety. As for the alkali metal hydroxide, specifically, for example, sodium hydroxide, potassium hydroxide and the like can be mentioned.

[0040] When containing the alkali agent, the content is preferably 0.01 to 2% by mass, more preferably 0.1 to 0.5% by mass, based on the total mass of the developer of the present invention.

[0041] 〔Chelating agent〕 The developer of the present invention preferably contains a chelating agent because it can suppress the aggregation of development residues. Specific examples of the chelating agent include citric acid, ethylenediaminetetraacetic acid (EDTA), ethylenediamine-N,N'-disuccinic acid (EDDS), L-glutamic acid diacetic acid (GLDA), and alkali metal salts thereof.

[0042] 〔Other components〕 The developer of the present invention can be blended with various additives as optional components as necessary. Examples of the additives include alkanolamines such as ethanolamine; preservatives such as benzotriazole and benzoic acid; freezing point depressants such as glycols (for example, ethylene glycol etc.) and lower alcohols (for example, ethanol etc.); antifoaming agents such as silicones and polyols; etc., which can be appropriately blended within a range not impairing the effects of the present invention.

[0043] 〔Developing method〕 Examples of the developing method using the developer of the present invention include the same methods as those using conventionally known aqueous developers. For example, a method in which the developer is brought into contact with the unexposed portion of the flexographic printing plate original plate, and physical actions such as brushing, water pressure, and ultrasonic waves are applied to disperse and remove the photosensitive layer (photosensitive resin composition) constituting the unexposed portion in the developer. At this time, the developer may immerse the unexposed portion, or may be continuously supplied and brought into contact when the physical action is exerted. Also, the temperature of the developer during development is preferably 20 to 60°C, more preferably 30 to 50°C. Also, as the physical force usually used, a brush is used, and the material, thickness, length, density of the hair, arrangement, movement of the brush, rotation direction, etc. are appropriately selected.

[0044] [Aqueous developing concentrate for flexographic printing plate] The aqueous developing concentrate for a flexographic printing plate of the present invention (hereinafter also abbreviated as "the concentrate of the present invention") is a concentrate of an aqueous developing solution for a flexographic printing plate, and is a concentrate containing an anionic surfactant, a nonionic surfactant, and water.

[0045] [Anionic surfactant] The anionic surfactant contained in the concentrate of the present invention is not particularly limited, and a conventionally known anionic surfactant can be used. Examples of the anionic surfactant include fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkyl sulfosuccinates, linear alkylbenzene sulfonates, branched alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxypolyoxyethylene propyl sulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salts, N-alkyl sulfosuccinic monoamide disodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow, sulfuric acid esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, sulfuric acid esters of fatty acid monoglycerides, polyoxyethylene alkylphenyl ether sulfate esters, polyoxyethylene styrylphenyl ether sulfate esters, alkyl phosphate esters, polyoxyethylene alkyl ether phosphate esters, polyoxyethylene alkylphenyl ether phosphate esters, partially saponified products of styrene-maleic anhydride copolymers, partially saponified products of olefin-maleic anhydride copolymers, naphthalenesulfonate formalin condensates, and the like.

[0046] In the present invention, for the developer prepared by diluting the concentrate of the present invention, since the formation of a film formed on the liquid surface can be suppressed, the anionic surfactant is preferably a compound represented by the above formula (1).

[0047] In the present invention, for the developer prepared by diluting the concentrate of the present invention, since the formation of a film formed on the liquid surface can be suppressed, R in the above formula (1) 1 preferably has 6 to 14 carbon atoms. Specifically, R in the above formula (1) 1 is more preferably an alkyl group having 6 to 14 carbon atoms, and in development using the developer prepared by diluting the concentrate of the present invention, since aggregation of development scum (dispersion) can be suppressed, it is even more preferably an alkyl group having 6 to 10 carbon atoms.

[0048] In the present invention, regarding the developer prepared by diluting the concentrated solution of the present invention, since the formation of a film on the liquid surface can be suppressed, the compound represented by the above formula (1) preferably has an HLB value of 8 or less and is water-soluble. Further, the compound represented by the above formula (1) preferably has an HLB value of 3 or more.

[0049] In the present invention, the content of the anionic surfactant is preferably 0.02 to 40% by mass, more preferably 3 to 25% by mass, based on the total mass of the concentrated solution of the present invention.

[0050] 〔Nonionic surfactant〕 The nonionic surfactant contained in the concentrated solution of the present invention is not particularly limited, and the nonionic surfactant described in the above-described developer of the present invention can be used.

[0051] In the present invention, since the storage stability becomes better and the aggregation of development residues (dispersions) can be suppressed in development using the developer prepared by diluting the concentrated solution of the present invention, the nonionic surfactant is preferably a compound represented by the above formula (2).

[0052] In the present invention, the content of the nonionic surfactant is preferably 0.02 to 40% by mass, more preferably 3 to 25% by mass, based on the total mass of the concentrated solution of the present invention.

[0053] 〔Water〕 The water contained in the concentrated solution of the present invention is not particularly limited, and the water described in the above-described developer of the present invention can be used. The content of water contained in the concentrated solution of the present invention is not particularly limited because it can be adjusted according to the degree of concentration, but it is preferably less than 80% by mass, more preferably 50% to less than 80% by mass, based on the total mass of the concentrated solution of the present invention.

[0054] 〔Alkali agent〕 The concentrated solution of the present invention preferably contains an alkali agent because the developability is good when using a developer prepared by diluting the concentrated solution of the present invention. The alkali agent is not particularly limited, and the alkali agents described in the developer of the present invention described above can be used. Moreover, when containing an alkali agent, the content is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total mass of the concentrated solution of the present invention.

[0055] 〔Chelating agent〕 The concentrated solution of the present invention preferably contains a chelating agent because the aggregation of development residues can be suppressed in the development using a developer prepared by diluting the concentrated solution of the present invention. The chelating agent is not particularly limited, and the chelating agents described in the developer of the present invention described above can be used.

[0056] 〔Other components〕 The concentrated solution of the present invention can be blended with various additives as optional components as necessary. Examples of the additives include alkanolamines such as ethanolamine; preservatives such as benzotriazole and benzoic acid; freezing point depressants such as glycols (e.g., ethylene glycol, etc.) and lower alcohols (e.g., ethanol, etc.); antifoaming agents such as silicones and polyols; etc., which can be appropriately blended within a range not impairing the effects of the present invention.

[0057] 〔Developing method〕 The developing method using the concentrated solution of the present invention includes the same methods as the developing methods using conventionally known aqueous developers, except for using an aqueous developer obtained by diluting the concentrated solution of the present invention. For example, an aqueous developer is brought into contact with the unexposed portion of the flexographic printing plate original plate, and physical actions such as brushing, water pressure, and ultrasonic waves are applied to disperse and remove the photosensitive layer (photosensitive resin composition) constituting the unexposed portion in the aqueous developer. Here, the dilution method of the concentrated solution of the present invention is not particularly limited, and for example, a method of diluting 2 to 20 times with water can be mentioned. Also, the aqueous developer may be immersed in the unexposed areas, or may be continuously supplied and brought into contact when a physical action is exerted. Also, the temperature of the aqueous developer during development is preferably 20 to 60°C, more preferably 30 to 50°C. Also, as the physical force usually used, a brush is used, and the material, thickness, length, density of the bristles, arrangement, movement of the brush, rotation direction, etc. are appropriately selected.

[0058] 〔Flexographic printing plate original〕 The photosensitive layer (photosensitive resin composition) of the flexographic printing plate original developed using the developer or concentrate of the present invention can use a conventionally known photosensitive resin composition. For example, resin compositions containing a water-dispersed latex, rubber, photopolymerizable monomer, photoinitiator, surfactant, etc. can be mentioned.

[0059] <Water-dispersed latex> The water-dispersed latex contained in the resin composition is not particularly limited, and a water-dispersed latex conventionally used in flexographic printing plates can be used. Specific examples of the water-dispersed latex include water-dispersed latex polymers such as polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, methyl methacrylate-butadiene copolymer latex, vinyl pyridine polymer latex, butyl polymer latex, thiokol polymer latex, acrylate polymer latex, etc.; polymers obtained by copolymerizing other components such as acrylic acid and methacrylic acid with these polymers; etc. These can be used alone or in combination of two or more.

[0060] <Rubber> The rubber contained in the resin composition is not particularly limited, and a rubber material conventionally used in flexographic printing plates can be used. As the rubber, specifically, for example, butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, urethane rubber, isoprene rubber, styrene-isoprene rubber, styrene-butadiene rubber, ethylene-propylene copolymer, chlorinated polyethylene, etc. can be mentioned, and these may be used alone or in combination of two or more.

[0061] <Photopolymerizable monomer> The photopolymerizable monomer contained in the resin composition is not particularly limited, and a photopolymerizable monomer conventionally used in flexographic printing plates can be used. Examples of the photopolymerizable monomer include ethylenically unsaturated compounds. Specific examples of the ethylenically unsaturated compound include, for example, (meth)acrylic monomers, (meth)acrylic oligomers, (meth)acrylic-modified polymers, etc. Specific examples of the (meth)acrylic-modified polymer include, for example, (meth)acrylic-modified butadiene rubber, (meth)acrylic-modified nitrile rubber, etc. Note that “(meth)acrylic” is a notation meaning acrylic or methacrylic.

[0062] <Photopolymerization initiator> The photopolymerization initiator contained in the resin composition is not particularly limited as long as it can initiate the photopolymerization of the above-mentioned photopolymerizable monomer. For example, photopolymerization initiators such as alkylphenones, acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzyles, biacetyls, etc. can be mentioned. Specifically, for example, benzyldimethylketal, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methyl-o-benzoylbenzoate, 1-hydroxycyclohexyl phenyl ketone, etc. can be mentioned.

[0063] <Surfactant> From the perspective of improving water developability, it is preferable that the resin composition contained in the resin composition contains a surfactant. Examples of the surfactant include cationic surfactants, anionic surfactants, and nonionic surfactants. Among them, anionic surfactants are preferable.

[0064] Specific examples of the anionic surfactant include, for example, aliphatic carboxylates such as sodium laurate and sodium oleate; higher alcohol sulfate esters such as sodium lauryl sulfate, sodium cetyl sulfate, and sodium oleyl sulfate; polyoxyethylene alkyl ether sulfate esters such as sodium polyoxyethylene lauryl ether sulfate; polyoxyethylene alkyl allyl ether sulfate esters such as sodium polyoxyethylene octyl phenyl ether sulfate and sodium polyoxyethylene nonyl phenyl ether sulfate; alkyl sulfonates such as alkyl diphenyl ether disulfonate, sodium dodecyl sulfonate, and sodium dialkyl sulfosuccinate; alkyl allyl sulfonates such as alkyl disulfonate, sodium dodecylbenzenesulfonate, sodium dibutylnaphthalenesulfonate, and sodium triisopropylnaphthalenesulfonate; higher alcohol phosphate esters such as sodium lauryl phosphate monoester and sodium lauryl phosphate diester; polyoxyethylene alkyl ether phosphate esters such as sodium polyoxyethylene lauryl ether phosphate monoester and sodium polyoxyethylene lauryl ether phosphate diester; and the like. These may be used alone or in combination of two or more.

[0065] [Method for Manufacturing Flexographic Printing Plate] The method for manufacturing a flexographic printing plate of the present invention includes an exposure step of imagewise exposing a photosensitive layer on a flexographic printing plate original, and after the exposure step, developing with the aqueous developer for a flexographic printing plate of the present invention described above, or a solution obtained by diluting the aqueous developer concentrate for a flexographic printing plate of the present invention described above 2 to 20 times to form a non-image portion and an image portion, and a rinsing step of rinsing with water after the developing step.

[0066] 〔Exposure step〕 The above exposure step is a step of irradiating the photosensitive layer with actinic rays in an imagewise manner to cause crosslinking and / or polymerization in the irradiated area of the actinic rays and to cure it.

[0067] The above exposure step can be carried out by exposing through a mask provided on the outer surface side of the photosensitive layer. Also, it is preferably carried out using a vacuum frame exposure apparatus. In that case, after exhausting the air between the relief forming layer and the mask, exposure with actinic rays is carried out. Also, the exposure may be carried out in a state where the oxygen concentration is reduced, or may be carried out in the atmosphere, and is not particularly limited. However, from the viewpoint of preventing polymerization inhibition by oxygen, it is preferable to carry out the exposure at a low oxygen concentration.

[0068] 〔Developing step〕 The above developing step is a step of developing with the aqueous developer for a flexographic printing plate of the present invention described above, or a solution obtained by diluting the aqueous developer concentrate for a flexographic printing plate of the present invention described above 2 to 20 times to form a non-image portion and an image portion, and specifically, it is as described in the developing method of the developer or developer concentrate of the present invention described above.

[0069] 〔Rinsing step〕 The above rinsing step is a step of rinsing the surfaces of the non-image portion and the image portion formed in the above developing step with water. As the rinsing means in the above rinsing step, there are methods such as rinsing with tap water, spraying high-pressure water, and using a batch-type or conveyor-type brush-type developing machine known as a flexographic printing plate developing machine to mainly brush the surfaces of the non-image area and the image area in the presence of water.

Examples

[0070] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0071] [Examples 1 to 11 and Comparative Examples 1 to 5] An aqueous developer was prepared by blending water, an alkali agent, a chelating agent, an anionic surfactant, and a nonionic surfactant in the parts by mass shown in Table 1 below.

[0072] 〔Concentration suitability〕 Regarding the aqueous developer concentrate obtained by concentrating the concentration of the alkali agent and the like in the prepared aqueous developer by 10 times, the dissolution state at room temperature (23 °C) was visually observed and evaluated according to the following criteria. The results are shown in Table 1 below. Note that if the evaluation is B or higher, there is no practical problem. (Evaluation criteria) A: Colorless and transparent B: Cloudy C: Two-layer separation D: Insoluble precipitate

[0073] 〔Storage stability〕 <50 °C / 45 days> After storing the aqueous developer concentrate used in the evaluation of concentration suitability in an oven at 50 °C for 45 days, the liquid state was visually observed and evaluated according to the following criteria. The results are shown in Table 1 below. Note that if the evaluation is B or higher, there is no practical problem. Also, for Comparative Examples 1 to 4, since insoluble matters occurred in the state before storage, no evaluation was performed, and in Table 1 below, it is indicated as "-". (Evaluation criteria) A: Colorless and transparent B: Cloudiness C: Two-layer separation

[0074] <-5°C / 60 days> The aqueous developing concentrate used in the evaluation of concentration suitability was stored in a -5°C freezer for 60 days, and then the liquid state was visually observed. Also, when the evaluation liquid was frozen, the time until remelting was measured. Evaluation was carried out according to the following criteria. The results are shown in Table 1 below. Note that if the evaluation is B or higher, there are no practical problems. Also, for Comparative Examples 1 to 4, since two-layer separation occurred before storage, no evaluation was performed, and in Table 1 below, it is indicated as "-". (Evaluation criteria) A: Does not freeze B: The time until remelting after leaving the freezer is less than 6 hours C: The time until remelting after leaving the freezer is 6 hours or more

[0075] 〔Developability〕 The cover film of a flexographic printing plate original [FLENEX FW-L2, manufactured by Fuji Film Co., Ltd.] was peeled off, and from the substrate side, it was exposed for 2 seconds at a distance of 15 cm using an exposure device with 15 chemical lamps of 40 W (back exposure). Thereafter, development was carried out for 3 minutes using a brush-type developing machine (liquid temperature 50°C) filled with each prepared aqueous developer. Thereafter, drying was carried out with hot air at 60°C until the moisture was removed. For the obtained flexographic printing plate, the thickness was measured using a constant-pressure thickness measuring instrument, and the film thickness change per minute (development speed) was calculated from the thickness change before and after development. Then, evaluation was carried out according to the following criteria. The results are shown in Table 1 below. Note that if the evaluation is B or higher, there are no practical problems. (Evaluation criteria) A: Development speed is 170 μm / min or more B: Development speed is 100 μm / min or more and less than 170 μm / min C: Development speed is less than 100 μm / min

[0076] 〔Agglomerated debris〕 The cover film of a flexographic printing plate original plate [FLENEX FW-L2, manufactured by Fuji Film Co., Ltd.] was peeled off, and from the substrate side, it was exposed (back exposure) for 2 seconds at a distance of 15 cm using an exposure device with 15 chemical lamps of 40 W arranged side by side. Subsequently, development was carried out for an arbitrary time in a brush-type developing machine (liquid temperature: 50°C) containing each prepared aqueous developer so that the solid content of the development waste (dispersion) was 7.0% by mass. The solid content of the development waste was measured by weighing 2.0 g of the used aqueous developer (hereinafter also abbreviated as "fatigue liquid"), drying it at 95°C for 18 hours, and calculating the solid content percentage in the fatigue liquid from the weight change before and after drying. Next, 7 g of the fatigue liquid was weighed into a container, diluted by adding 63 g of hard water with a hardness of 120, and the agglomerated waste generated immediately after stirring was observed and evaluated according to the following criteria. The results are shown in Table 1 below. If the evaluation is B or higher, there is no practical problem. (Evaluation Criteria) A: No aggregates are generated, and no deposits are generated at the gas-liquid interface of the container. B: No aggregates are generated, but deposits are generated at the gas-liquid interface of the container. C: Aggregates are generated.

[0077] 〔Film Suppression〕 The cover film of a flexographic printing plate original plate [FLENEX FW-L2, manufactured by Fuji Film Co., Ltd.] was peeled off, and from the substrate side, it was exposed (back exposure) for 2 seconds at a distance of 15 cm using an exposure device with 15 chemical lamps of 40 W arranged side by side. Subsequently, development was carried out for an arbitrary time in a brush-type developing machine (liquid temperature: 50°C) containing each prepared aqueous developer so that the solid content of the development waste (dispersion) was 7.0% by mass. The solid content of the development waste was measured by weighing 2.0 g of the used aqueous developer (hereinafter also abbreviated as "fatigue liquid"), drying it at 95°C for 18 hours, and calculating the solid content percentage in the fatigue liquid from the weight change before and after drying. Next, 50 g of the fatigue liquid was weighed into a container, heated in an oven at 50°C for 5 hours with the lid open, and then left at room temperature (23°C) for 12 hours. After that, the film strength on the liquid surface was visually observed and evaluated according to the following criteria. The results are shown in Table 1 below. If the evaluation is B or higher, there is no practical problem. (Evaluation Criteria) A: No film formation B: Film forms, but can be redispersed after stirring C: Film forms and cannot be redispersed even after stirring

[0078]

Table 1

[0079] The following were used for each component in Table 1 above. · Sodium carbonate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · EDDS: Octquest E30 (manufactured by Inno Spec specialty chemicals Corporotaion) · Sodium pentanoate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · Sodium octanoate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · Sodium laurate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · Sodium lauryl sulfate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · Sodium lauryl sulfonate: Reagent manufactured by Fuji Film Wako Pure Chemical Corporation · Sodium lauryl phosphate: Reagent manufactured by Tokyo Chemical Industry Co., Ltd. · Ionin D-6120: Polyoxyethylene polystyryl phenyl ether (manufactured by Takemoto Yushi Co., Ltd.) · Ionin D-1105: Polyoxyethylene lauryl ether (manufactured by Takemoto Yushi Co., Ltd.) · Polyoxyethylene nonyl phenyl ether: Emulgen 905 (manufactured by Kao Corporation)

[0080] As shown in Table 1 above, it was found that when no nonionic surfactant was blended and only anionic surfactants were blended, the concentration suitability was poor (Comparative Examples 1 to 4). Also, when no anionic surfactant was blended and only nonionic surfactants were blended, it was found that the storage stability was poor (Comparative Example 5).

[0081] On the other hand, it was found that by blending both an anionic surfactant and a nonionic surfactant, the concentrate suitability was excellent and the storage stability was also good (Examples 1 to 11). In particular, from the comparison between Example 2 and Example 7, and the comparison between Example 3 and Example 8, etc., it was found that when an alkaline agent was blended, the developability using an aqueous developer prepared by diluting the concentrate was better. Also, from the comparison of Examples 1 to 6, it was found that when the anionic surfactant is a compound represented by the above formula (1), the formation of a film on the liquid surface of an aqueous developer prepared by diluting the concentrate can be suppressed. Further, from the comparison between Example 8 and Example 9, it was found that when the nonionic surfactant is a compound represented by the above formula (2), the aggregation of development residues (dispersions) can be suppressed in development using an aqueous developer prepared by diluting the concentrate.

Claims

1. A concentrated aqueous developer for flexographic printing plates, wherein the aqueous developer for flexographic printing plates contains an anionic surfactant, a nonionic surfactant, water, and an alkali agent, the anionic surfactant is a compound represented by the following formula (1), the nonionic surfactant is at least one of polyoxyethylene alkyl ether, polyoxyethylene polystyryl phenyl ether, and a compound represented by the following formula (2), the alkali agent is an alkali metal carbonate or an alkali metal hydroxide, and the content of the alkali agent is 0.01 to 2% by mass based on the total mass of the aqueous developer for flexographic printing plates. The concentrated aqueous developer for flexographic printing plates is an aqueous developer for flexographic printing plates. R １ -X １ ...(1) Here, in the formula (1), R １ represents an alkyl group having 6 to 14 carbon atoms, an alkenyl group having 6 to 14 carbon atoms, or an alkynyl group having 6 to 14 carbon atoms, which may have a substituent. X １ represents a sulfate group or a salt thereof, or a sulfonic acid group or a salt thereof. 【Chemical 1】 Here, in the formula (2), Ar represents an m-valent aromatic group, and m represents an integer of 2 to 8. X2 represents a monovalent organic group having 6 to 14 carbon atoms, and p represents an integer of 1 to 3. However, p < m, and when p is 2 or 3, a plurality of X2 may be the same or different from each other. A represents an alkylene group having 2 to 4 carbon atoms, R2 represents a hydrogen atom or an alkyl group, and n represents an integer of 5 to 50. A plurality of A, n, and R2 may all be the same or different from each other.

2. The concentrated aqueous developer for flexographic printing plates according to claim 1, wherein the content of the anionic surfactant in the aqueous developer for flexographic printing plates is 0.01 to 10% by mass, and the content of the nonionic surfactant is 0.01 to 10% by mass.

3. The concentrated aqueous developer for flexographic printing plates according to claim 1 or 2, wherein the compound represented by the formula (1) has an HLB value of 8 or less and is water-soluble.

4. The concentrated aqueous developer for flexographic printing plates according to any one of claims 1 to 3, wherein the nonionic surfactant is polyoxyethylene polystyryl phenyl ether.

5. The concentrated aqueous developer for flexographic printing plates according to any one of claims 1 to 3, wherein the nonionic surfactant is a compound represented by the formula (2).

6. The flexographic printing plate aqueous developing concentrate according to any one of claims 1 to 5, wherein the content of the anionic surfactant is 0.02 to 40% by mass and the content of the nonionic surfactant is 0.02 to 40% by mass with respect to the total mass of the flexographic printing plate aqueous developing concentrate.

7. A method for manufacturing a flexographic printing plate having a non-image area and an image area, an exposure step of exposing the photosensitive layer of the flexographic printing plate original having a photosensitive layer in an image-like manner, a developing step of forming a non-image area and an image area by developing using a solution obtained by diluting the flexographic printing plate aqueous developing concentrate according to any one of claims 1 to 6 by 2 to 20 times after the exposure step, and a rinsing step of rinsing with water after the developing step. A method for manufacturing a flexographic printing plate.

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