Aqueous developer for flexographic printing plate and method for producing flexographic printing plate

Abstract

The present invention aims to provide an aqueous developer for flexographic printing plates, and a method for producing flexographic printing plates using the aqueous developer, wherein the aqueous developer for flexographic printing plates can maintain good developability and suppress aggregation of dispersions in the developer diluted with water after repeated use. The aqueous developer for flexographic printing plates of the present invention is an aqueous developer for flexographic printing plates containing a nonionic surfactant represented by the following formula (1) and water. 1 0‑(A0) n -H……(1), wherein in the above formula (1), R1 represents a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms. A represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 7 or greater, and when n is an integer of 2 or greater, a plurality of A's may be the same or different.

Description

Technical Field

[0001] The present invention relates to an aqueous developer for a flexographic printing plate and a method for producing a flexographic printing plate using the aqueous developer. Background Art

[0002] In recent years, there has been a trend across various industries to reduce the use of organic solvents from the perspective of improving the working environment and preserving the global environment. Consequently, the use of aqueous-developable photosensitive resin plates has been increasing in the platemaking process of photosensitive flexographic printing plates used for printing.

[0003] For example, Patent Document 1 describes “an aqueous developer composition for a photosensitive resin, the aqueous developer comprising at least a surfactant (A), a pH adjuster (B), a cleaning accelerator (C), and water, wherein the surfactant (A) comprises at least an alkylene oxide adduct of a primary alcohol having 6 to 8 carbon atoms and an HLB of 12 to 16, the pH adjuster (B) is an inorganic salt, the pH of the aqueous developer is 8 to 13, and the cleaning accelerator (C) comprises a compound represented by the following formula (I) or (II).

[0004] RO(AO) n R1……(I)

[0005] C n H 2n+2 …………(II)

[0006] In the above formula (I), R and R1 are alkyl or alkenyl groups having 2 to 6 carbon atoms, A is an alkylene group having 2 to 4 carbon atoms, and n is a number of 1 to 5.

[0007] In the above formula (II), n is 6 to 20. ”

[0008] Previous technical literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-317660 Summary of the Invention

[0011] Technical issues to be solved by the invention

[0012] The present inventors have studied the aqueous developer described in Patent Document 1 and have found that the developing properties are good. However, the present inventors have discovered that there is a problem in that if the aqueous developer is repeatedly used for development more than twice, when the developer remaining on the printing plate or on the bath wall of the developing device is washed (rinsed) with water, the dispersed matter aggregates in the developer diluted with water and reattaches to the printing plate, thereby causing dirt on the printed material and affecting the maintainability of the developing device.

[0013] Therefore, an object of the present invention is to provide an aqueous developer for flexographic printing plates that can maintain good developability and suppress aggregation of dispersions in the developer diluted with water after repeated use, and a method for producing a flexographic printing plate using the aqueous developer.

[0014] Means for solving technical problems

[0015] The present inventors have conducted intensive studies to solve the above problems and have found that an aqueous developer containing a nonionic surfactant having a predetermined structure can maintain good developability and suppress aggregation of dispersions in the developer diluted with water after repeated use, thereby completing the present invention.

[0016] That is, the present inventors have found that the above-mentioned problems can be achieved by the following configuration.

[0017] [1] An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1) and water.

[0018] R 1 O-(AO) n -H……(1)

[0019] Here, in the above formula (1),

[0020] R 1 It represents a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms.

[0021] A represents an alkylene group having 2 to 4 carbon atoms.

[0022] n represents an integer of 7 or greater. When n is an integer of 2 or greater, a plurality of A's may be the same as or different from each other.

[0023] [2] The aqueous developer for a flexographic printing plate according to [1], wherein n in the formula (1) represents an integer greater than or equal to 10.

[0024] [3] The aqueous developer for flexographic printing plates according to [1] or [2], wherein n in the formula (1) represents an integer of 15 or greater.

[0025] [4] The aqueous developer for flexographic printing plates according to any one of [1] to [3], wherein R in the formula (1) 1 It has ethylenically unsaturated double bonds.

[0026] [5] The aqueous developer for flexographic printing plates according to any one of [1] to [4], further comprising an anionic surfactant represented by the following formula (2).

[0027] R 2-X……(2)

[0028] Here, in the above formula (2),

[0029] R 2 It represents an aliphatic hydrocarbon group having 7 to 15 carbon atoms.

[0030] X 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.

[0031] [6] A method for manufacturing a flexographic printing plate, the flexographic printing plate having a non-image portion and an image portion, the method comprising:

[0032] An exposure step is to expose the flexographic printing plate precursor having a photosensitive layer in an image-wise manner.

[0033] a developing step, after the exposure step, developing the flexographic printing plate using the aqueous developer described in any one of [1] to [5] to form a non-image area and an image area; and

[0034] The rinsing process is performed after the development process using water.

[0035] Effects of the Invention

[0036] The present invention provides an aqueous developer for flexographic printing plates that can maintain good developability and suppress aggregation of dispersions in the developer diluted with water after repeated use, and a method for producing a flexographic printing plate using the aqueous developer. DETAILED DESCRIPTION

[0037] Hereinafter, the present invention will be described in detail.

[0038] The following description of the constituent elements is based on representative embodiments of the present invention, but the present invention is not limited to these embodiments.

[0039] In addition, in this specification, the numerical range expressed using "to" means a range including the numerical values described before and after "to" as the lower limit and the upper limit.

[0040] Furthermore, in this specification, each component may be used alone or in combination of two or more substances. When two or more substances are used simultaneously for each component, the content of the component refers to the total content of the substances used simultaneously, unless otherwise specified.

[0041] [Water-based developer for flexographic printing plates]

[0042] The aqueous developer for flexographic printing plates of the present invention (hereinafter also referred to as the "aqueous developer of the present invention") is an aqueous developer for flexographic printing plates containing a nonionic surfactant represented by formula (1) described later (hereinafter also referred to as the "specific surfactant") and water.

[0043] In the present invention, as described above, the aqueous developer containing the specific surfactant can maintain good developability and suppress aggregation of dispersions in the developer diluted with water after repeated use.

[0044] Although the details are not yet clear, the present inventors speculate as follows.

[0045] First, aqueous developers can generally be reused for development more than twice, but for example, the developer used for the second development contains the plate material removed from the flexographic printing plate precursor by the first development, i.e., the unexposed (uncured) portion of the plate material.

[0046] Therefore, it is considered that this is because, in the present invention, by adding a specific surfactant, the specific surfactant is adsorbed to the dispersion, and thus the adsorption state can be maintained even when the dispersion is diluted with water in the rinsing step.

[0047] Specifically, it is considered that in the formula (1) described later, R 1 The linear aliphatic hydrocarbon group represented has 9 to 30 carbon atoms, thereby improving affinity with the dispersed matter, and thus being able to maintain an adsorbed state even when diluted with water.

[0048] Furthermore, it is considered that in the formula (1) described later, when n is an integer of 7 or more, the alkylene oxide becomes larger, and as a result, the steric repulsion between the dispersions becomes larger, thereby suppressing the aggregation of the dispersions.

[0049] Hereinafter, each component contained in the aqueous developer of the present invention will be described in detail.

[0050] 〔Specific surfactant〕

[0051] The specific surfactant contained in the aqueous developer of the present invention is a nonionic surfactant represented by the following formula (1).

[0052] R 1 O-(AO) n -H……(1)

[0053] Here, in the above formula (1),

[0054] R 1 It represents a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms.

[0055] A represents an alkylene group having 2 to 4 carbon atoms.

[0056] n represents an integer of 7 or greater. When n is an integer of 2 or greater, a plurality of A's may be the same as or different from each other.

[0057] As R in the above formula (1) 1 Examples of the linear aliphatic hydrocarbon group having 9 to 30 carbon atoms include an alkyl group, an alkenyl group, and an alkynyl group.

[0058] Here, the alkenyl group refers to a monovalent group obtained by removing one hydrogen atom from any carbon atom of an alkene, and the free atomic valence may be on an unsaturated carbon atom or a saturated carbon atom.

[0059] Furthermore, the alkynyl group refers to a monovalent group obtained by removing one hydrogen atom from any carbon atom of an alkyne, and the free atomic valence may be on an unsaturated carbon atom or a saturated carbon atom.

[0060] Specific examples of the alkyl group include a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.

[0061] Specific examples of the alkenyl group include nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, and octadecenyl.

[0062] Specific examples of the alkynyl group include nonynyl, decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, pentadecynyl, hexadecynyl, heptadecenyl, and octadecynyl.

[0063] And, R 1 The linear aliphatic hydrocarbon group represented has 9 to 30 carbon atoms, preferably 10 to 20 carbon atoms, and more preferably 12 to 18 carbon atoms.

[0064] In the present invention, it is preferred that R in the above formula (1) is 1 It has an ethylenically unsaturated double bond (carbon-carbon double bond), and more preferably has one carbon-carbon double bond.

[0065] A in the above formula (1) represents an alkylene group having 2 to 4 carbon atoms, and is preferably an alkylene group having 2 or 3 carbon atoms, and more preferably a vinyl group or an n-propylene group.

[0066] In the above formula (1), n represents an integer of 7 or greater, and is preferably an integer of 10 or greater, more preferably an integer of 15 or greater, because aggregation of the dispersion can be further suppressed.

[0067] Furthermore, the upper limit of n in the above formula (1) is not particularly limited, but is preferably 40 or less, and more preferably 25 or less.

[0068] In the present invention, the HLB (Hydrophile-Lipophile Balance) value of the specific surfactant is preferably 10 to 17, and more preferably 12 to 15, because it can further suppress aggregation of the dispersion. An HLB value of 10 to 17 can appropriately suppress the solubility of the specific surfactant in water, allowing a stable emulsion (suspension) to be formed, and thus it is believed that aggregation of the dispersion can be further suppressed.

[0069] Here, the HLB value is a value obtained by Griffin's calculation formula.

[0070] In Griffin's calculation formula, the HLB value is calculated according to the following formula using the value of S (saponification value of ester) and the value of N (neutralization value of fatty acids constituting the ester).

[0071] The closer the HLB value is to 20, the more hydrophilic it is, and the closer it is to 0, the more lipophilic it is.

[0072] HLB value = 20 (1-S / N)

[0073] Specific examples of the specific surfactant include polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether.

[0074] In the present invention, the content of the specific surfactant is preferably 0.1 to 20% by mass, more preferably 0.1 to 10% by mass, and even more preferably 0.5 to 5% by mass.

[0075] 〔water〕

[0076] The water contained in the aqueous developer of the present invention is not particularly limited, and any of purified water, distilled water, ion-exchanged water, pure water, and ultrapure water such as Milli-Q water can be used. In addition, Milli-Q water is ultrapure water obtained by using an ultrapure water production device, namely a Milli-Q water production device, manufactured by Merck KGaA.

[0077] The content of water contained in the aqueous 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 aqueous developer.

[0078] [Anionic surfactant]

[0079] The aqueous developer of the present invention preferably contains an anionic surfactant represented by the following formula (2) because the developability is further improved and the stability of the concentrated solution obtained by concentrating the aqueous developer is improved.

[0080] R 2 -X……(2)

[0081] Here, in the above formula (2),

[0082] R 2 It represents an aliphatic hydrocarbon group having 7 to 15 carbon atoms.

[0083] X 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.

[0084] As R in the above formula (2) 2 Examples of the aliphatic hydrocarbon group having 7 to 15 carbon atoms include an alkyl group, an alkenyl group, and an alkynyl group.

[0085] Specific examples of the alkyl group include linear alkyl groups such as octyl, nonyl, decyl, dodecyl, and tetradecyl; and branched alkyl groups such as isooctyl, 2-ethylhexyl, isodecyl, isododecyl, and isotetradecyl.

[0086] Specific examples of the alkenyl group include heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, and pentadecenyl.

[0087] Specific examples of the alkynyl group include heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, and pentadecynyl.

[0088] As described above, X in the above formula (2) represents a carboxylic acid group or a salt thereof, a sulfonic acid group (-SO3H) or a salt thereof, a sulfuric acid group (-OSO3H) or a salt thereof, or a phosphoric acid group (-OPO3H2) or a salt thereof, among which, preferably, it is a carboxylic acid group (-COOH) or a salt thereof, a sulfonic acid group or a salt thereof, or a sulfuric acid group or a salt thereof, and more preferably, it is a carboxylic acid group or a salt thereof.

[0089] Furthermore, the salt of the carboxylic acid group or the like is preferably an alkali metal salt such as a sodium salt or a potassium salt.

[0090] Specific examples of the anionic surfactant represented by the above formula (2) include sodium laurate, potassium laurate, sodium oleate, and potassium palmitate.

[0091] In the present invention, the content of the anionic surfactant represented by the above formula (2) is preferably 0.01 to 10% by mass, more preferably 0.1 to 2% by mass, relative to the total mass of the aqueous developer.

[0092] [Alkali]

[0093] The aqueous developer of the present invention preferably contains an alkali agent because the developability becomes more favorable.

[0094] Examples of the alkali agent include alkali metal carbonates and alkali metal hydroxides.

[0095] Among them, specific examples of the alkali metal include sodium, potassium, and calcium.

[0096] Specific examples of the alkali metal carbonate include sodium carbonate and potassium carbonate. Among them, sodium carbonate is preferred from the viewpoint of safety.

[0097] Furthermore, specific examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

[0098] When the alkali agent is contained, the content is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, based on the total mass of the aqueous developer.

[0099] 〔Chelating agent〕

[0100] The aqueous developer of the present invention preferably contains a chelating agent because aggregation of the dispersion can be further suppressed.

[0101] 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.

[0102] [Other ingredients]

[0103] The aqueous developer of the present invention may contain various additives as optional components as needed.

[0104] As additives, for example, alkanolamines such as ethanolamine; preservatives such as benzotriazole and benzoic acid; freezing point depression agents such as glycols (for example, ethylene glycol, etc.) and lower alcohols (for example, ethanol, etc.); defoaming agents such as silicones and polyols; etc. can be appropriately added within the range that does not impair the effects of the present invention.

[0105] [Development Method]

[0106] Regarding the development method using the aqueous developer of the present invention, the same method as the development method using the conventionally known aqueous developer can be cited. For example, the following method can be cited, namely, the aqueous developer is brought into contact with the unexposed portion of the flexographic printing plate precursor, and a physical action such as a brush, water pressure, or ultrasound is applied, so that the photosensitive layer (photosensitive resin composition) constituting the unexposed portion is dispersed in the aqueous developer and removed.

[0107] At this time, the unexposed portion may be immersed in an aqueous developer, or the aqueous developer may be continuously supplied to contact the unexposed portion while applying a physical action.

[0108] Furthermore, regarding the aqueous developer, the liquid temperature during development is preferably 20 to 60°C, more preferably 30 to 50°C.

[0109] Furthermore, as a physical force commonly used, a brush is used, and the material, thickness, length, density and arrangement of the bristles, the movement and rotation direction of the brush, etc. can be appropriately selected.

[0110] 〔Flexographic printing plate〕

[0111] The photosensitive layer (photosensitive resin composition) of the flexographic printing plate precursor developed with the aqueous developer of the present invention can be a conventionally known photosensitive resin composition, for example, a resin composition containing a water-dispersible latex, rubber, a photopolymerizable monomer, a photopolymerization initiator, and a surfactant.

[0112] <Water-dispersible latex>

[0113] The water-dispersible latex contained in the resin composition is not particularly limited, and conventionally known water-dispersible latexes used for flexographic printing plates can be used.

[0114] Specific examples of the water-dispersible latex include water-dispersible 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, vinylpyridine polymer latex, butyl polymer latex, thiol polymer latex, and acrylate polymer latex; polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid; and the like. These may be used alone or in combination of two or more.

[0115] <Rubber>

[0116] The rubber contained in the resin composition is not particularly limited, and conventionally known rubber materials used for flexographic printing plates can be used.

[0117] Specific examples of the rubber include butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, polyurethane rubber, isoprene rubber, styrene isoprene rubber, styrene butadiene rubber, ethylene-propylene copolymer, and chlorinated polyethylene. These may be used alone or in combination of two or more.

[0118] <Photopolymerizable Monomer>

[0119] The photopolymerizable monomer contained in the resin composition is not particularly limited, and conventionally known photopolymerizable monomers used for flexographic printing plates can be used.

[0120] As a photopolymerizable monomer, an ethylenically unsaturated compound is mentioned, for example.

[0121] Specific examples of the ethylenically unsaturated compound include (meth)acrylic acid monomers, (meth)acrylic acid oligomers, and (meth)acrylic acid-modified polymers.

[0122] Specific examples of the (meth)acrylic acid-modified polymer include (meth)acrylic acid-modified butadiene rubber and (meth)acrylic acid-modified nitrile rubber.

[0123] In addition, "(meth)acrylic acid" is an expression which means acrylic acid or methacrylic acid.

[0124] <Photopolymerization Initiator>

[0125] The photopolymerization initiator contained in the resin composition is not particularly limited as long as it initiates the photopolymerization of the above-mentioned photopolymerizable monomers. Examples thereof include alkyl phenone-based, acetophenone-based, benzoin ether-based, benzophenone-based, thioxanthones-based, anthraquinone-based, benzyl-based, and diacetyl-based photopolymerization initiators.

[0126] Specific examples include benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methyl o-benzoylbenzoate, and 1-hydroxycyclohexyl phenyl ketone.

[0127] <Surfactant>

[0128] From the viewpoint of improving water developability, the resin composition preferably contains a surfactant.

[0129] Examples of the surfactant include cationic surfactants, anionic surfactants, and nonionic surfactants, among which anionic surfactants are preferred.

[0130] Specific examples of the anionic surfactant include

[0131] Aliphatic carboxylates such as sodium laurate and sodium oleate;

[0132] Sodium lauryl sulfate, sodium hexadecyl sulfate, sodium oleyl sulfate and other higher alcohol sulfates;

[0133] Polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate;

[0134] Polyoxyethylene alkyl allyl ether sulfate salts such as polyoxyethylene octylphenyl ether sodium sulfate and polyoxyethylene nonylphenyl ether sodium sulfate;

[0135] Alkyl sulfonates such as alkyl diphenyl ether disulfonate, sodium dodecyl sulfonate, and sodium dialkyl sulfosuccinate;

[0136] Alkyl allyl sulfonates such as alkyl disulfonates, sodium dodecylbenzenesulfonate, sodium dibutylnaphthalenesulfonate, and sodium triisopropylnaphthalenesulfonate;

[0137] Higher alcohol phosphate salts such as disodium lauryl phosphate monoester and sodium lauryl phosphate diester;

[0138] Polyoxyethylene lauryl ether monophosphate disodium, polyoxyethylene lauryl ether diester sodium, and other polyoxyethylene alkyl ether phosphate salts; etc.

[0139] These may be used alone or in combination of two or more.

[0140] [Method for manufacturing flexographic printing plates]

[0141] The method for manufacturing a flexographic printing plate of the present invention is a manufacturing method comprising the following steps: an exposure step, in which a flexographic printing plate precursor having a photosensitive layer is exposed to light in an image-like manner; a development step, in which, after the exposure step, the flexographic printing plate of the present invention is developed using an aqueous developer to form a non-image portion and an image portion; and a rinsing step, in which, after the development step, water is used for rinsing.

[0142] [Exposure process]

[0143] The exposure step is a step of irradiating the photosensitive layer with active light in an image-wise manner to cause crosslinking and / or polymerization in the region irradiated with the active light, thereby curing the layer.

[0144] The exposure step can be performed by exposing the photosensitive layer through a mask provided on the outer surface thereof.

[0145] Furthermore, it is also preferable to use a vacuum frame exposure apparatus. In this case, exposure with active light is performed after the air between the relief-forming layer and the mask is exhausted.

[0146] Furthermore, the exposure may be performed in a state with a reduced oxygen concentration or in the air without particular limitation. However, from the viewpoint of preventing polymerization inhibition due to oxygen, the exposure is preferably performed in a low oxygen concentration.

[0147] [Development process]

[0148] The development step is a step of forming a non-image area and an image area by developing using the aqueous developer of the present invention. The details are as described in the development method using the aqueous developer of the present invention.

[0149] 〔Rinsing process〕

[0150] The rinsing step is a step of rinsing the surfaces of the non-image area and the image area formed in the development step with water.

[0151] In the present invention, the developer remaining on the surface of the non-image area and the image area is the aqueous developer of the present invention. Therefore, even when the aqueous developer is diluted with water used in the rinsing step, adhesion and aggregation of the dispersed matter in the developer can be suppressed.

[0152] Examples of the rinsing method in the above-mentioned rinsing step include a method of washing with tap water, a method of spraying high-pressure water with a sprayer, a method of using a well-known intermittent or conveying brush-type washing machine as a developer for flexographic printing plates to mainly brush the surfaces of the non-image area and the image area in the presence of water, etc.

[0153] [use]

[0154] The aqueous developer for flexographic printing plates of the present invention can be used not only as an aqueous developer for flexographic printing plates but also as a cleaning liquid for cleaning the wall surface of a bath of a developing device.

[0155] Example

[0156] Hereinafter, the present invention will be further described in detail with reference to the following examples. The materials, usage amounts, ratios, processing contents, and processing sequences shown in the following examples may be appropriately modified without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being restrictive by the following examples.

[0157] [Synthesis of nonionic surfactant CW-1]

[0158] After adding potassium hydroxide to octanol to a concentration of 1 mass %, 20 molar equivalents of ethylene oxide were blown into 1 molar equivalent of octanol at 180±5°C to synthesize polyoxyethylene octyl ether. The number of moles of ethylene oxide added was confirmed by measuring the mass increase.

[0159] [Examples 1 to 7 and Comparative Examples 1 to 5]

[0160] An aqueous developer was prepared by blending water, an alkali agent, a nonionic surfactant, and an anionic surfactant shown in Table 1 below in parts by mass.

[0161] 〔evaluate〕

[0162] <Developability>

[0163] The cover film of the flexographic printing plate precursor [FLENEX FW-L2, manufactured by Fujifilm Corporation] was peeled off and exposed for 2 seconds (back exposure) from a position 15 cm from the substrate side using an exposure apparatus equipped with 15 arranged 40 W chemical lamps.

[0164] Thereafter, development was performed for 3 minutes using a brush washer (liquid temperature 50° C.) filled with each of the prepared aqueous developers.

[0165] Afterwards, it was dried by hot air at 60°C until the moisture was removed. The thickness of the obtained flexographic printing plate was measured using a constant pressure thickness gauge, and the film thickness change per minute (development speed) was calculated based on the thickness change before and after development. Then, it was evaluated according to the following benchmarks. The results are shown in Table 1 below. Practically, an evaluation of B or above is preferred.

[0166] (Evaluation Criteria)

[0167] A: Development speed is 170 μm / min or more

[0168] B: Development speed is 100 μm / min or more and less than 170 μm / min

[0169] C: Development speed less than 100μm / min

[0170] <Agglomeration Inhibition>

[0171] The cover film of the flexographic printing plate precursor [FLENEX FW-L2, manufactured by Fujifilm Corporation] was peeled off and exposed for 2 seconds (back exposure) from a position 15 cm from the substrate side using an exposure apparatus equipped with 15 arranged 40 W chemical lamps.

[0172] Subsequently, development was performed using a brush washer (liquid temperature 50°C) filled with each of the prepared aqueous developers for an arbitrary time period until the solid content of the development residue (dispersion) reached 7.0% by mass. Regarding the solid content of the development residue, 2.0 g of the aqueous developer used (hereinafter also referred to as "exhausted solution") was weighed and dried at 95°C for 18 hours. The solid content percentage in the exhausted solution was calculated based on the weight change before and after drying.

[0173] Next, 50 cc of the fatigue solution was placed in a 1000 cc plastic container containing 450 cc of water, stirred, and then allowed to stand for 12 hours. Agglomerates in the solution were visually observed and evaluated according to the following criteria. The results are shown in Table 1 below.

[0174] (Evaluation Criteria)

[0175] A: There are no large aggregates that can be identified by the naked eye

[0176] B: Produces some large aggregates that can be identified with the naked eye

[0177] C: Produces a small amount of large aggregates that can be identified by the naked eye

[0178] D: Produces a large number of large aggregates that can be identified by the naked eye

[0179] <Stability of Concentrate>

[0180] The aqueous developer concentrates prepared by concentrating each of the prepared aqueous developers at a 10-fold concentration ratio were visually observed for dissolution at room temperature (23°C) and evaluated according to the following criteria. The results are shown in Table 1. A rating of B or higher indicates no practical problems.

[0181] (Evaluation Criteria)

[0182] A: Colorless and transparent

[0183] B: White turbidity

[0184] C: Two-layer separation

[0185] D: Insoluble precipitate

[0186] [Table 1]

[0187]

[0188] The following components were used as the components in Table 1 above.

[0189] Sodium carbonate: Reagent manufactured by FUJIFILM Wako Pure Chemical Corporation

[0190] EMULGEN 108: Polyoxyethylene lauryl ether (HLB: 12.0, manufactured by Kao Corporation)

[0191] PIONIN D-1115: Polyoxyethylene lauryl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0192] PIONIN D-1315: Polyoxyethylene cetyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0193] PIONIN D-1323: Polyoxyethylene cetyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0194] PIONIN D-1420: Polyoxyethylene stearyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0195] PIONIN D-1518: Polyoxyethylene oleyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0196] PIONIN D-1004: Polyoxyethylene octyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0197] PIONIN D-1007: Polyoxyethylene octyl ether (manufactured by TAKEMOTO OIL & FAT CO., LTD.)

[0198] CW-1: A synthetic product of the above

[0199] EMULGEN 104P: Polyoxyethylene lauryl ether (HLB: 9.7, manufactured by Kao Corporation)

[0200] Polyoxyethylene (4) stearyl ether: a reagent manufactured by FUJIFILM Wako Pure Chemical Corporation

[0201] Sodium laurate: Reagent manufactured by FUJIFILM Wako Pure Chemical Corporation

[0202] As shown in Table 1 above, it is known that if R in the above formula (1) 1 When the aliphatic hydrocarbon group has 8 carbon atoms, aggregation of development residues cannot be suppressed regardless of the number of n in the above formula (1) (Comparative Examples 1 to 3).

[0203] Furthermore, it is known that even if R 1 It is a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms. If n in the above formula (1) is an integer smaller than 7, aggregation of the development residue cannot be suppressed and the stability of the concentrated solution is also poor (Comparative Examples 4 and 5).

[0204] On the other hand, it was found that when a specific surfactant was added, good developability could be maintained and aggregation of development residues could be suppressed (Examples 1 to 7).

[0205] In particular, from the comparison between Example 3 and Example 7, it is understood that when the anionic surfactant represented by the above formula (2) is added, the developability is further improved and the stability of the concentrated solution obtained by concentrating the aqueous developer is improved.

[0206] Furthermore, from the comparison between Example 5 and Example 6, it is known that if R in the above formula (1) 1 Having an ethylenically unsaturated double bond (carbon-carbon double bond) can further suppress aggregation of development residues in a fatigue solution.

Claims

1. An aqueous developer for a flexographic printing plate, comprising a nonionic surfactant represented by the following formula (1) and water, R 1 O-(AO) n -H (1) Here, in the formula (1), R 1 represents a straight-chain aliphatic hydrocarbon group having 16 to 30 carbon atoms, R 1 Having ethylenically unsaturated double bonds, A represents an alkylene group having 2 to 4 carbon atoms, n represents an integer of 7 or greater. When n is an integer of 7 or greater, a plurality of A's may be the same as or different from each other.

2. The aqueous developer for flexographic printing plates according to claim 1, wherein In the above formula (1), n represents an integer of 10 or greater.

3. The aqueous developer for flexographic printing plates according to claim 1 or 2, wherein In the above formula (1), n represents an integer of 15 or greater.

4. The aqueous developer for flexographic printing plates according to claim 1 or 2, further comprising an anionic surfactant represented by the following formula (2): R 2 -X (2) Here, in the formula (2), R 2 represents an aliphatic hydrocarbon group having 7 to 15 carbon atoms, X 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.

5. A method for manufacturing a flexographic printing plate, the flexographic printing plate having a non-image portion and an image portion, the method comprising: An exposure step of exposing a flexographic printing plate precursor having a photosensitive layer to image-wise exposure of the photosensitive layer; a developing step of developing the flexographic printing plate using an aqueous developer according to any one of claims 1 to 4 after the exposure step, thereby forming a non-image area and an image area; and The rinsing step is performed using water after the development step.

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