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

Abstract

To provide an aqueous developer for a flexographic printing plate capable of maintaining good developability and suppressing aggregation of a dispersion in the developer diluted with water after repeated use, and a manufacturing method of a flexographic printing plate using the same.SOLUTION: An aqueous developer for a flexographic printing plate of the present invention is an aqueous developer for a flexographic printing plate comprising a nonionic surfactant represented by Formula (1) and water. R1O-(AO)n-H (1). In 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; and n represents an integer of 7 or more, and in a case where n is an integer of 2 or more, a plurality of A may be the same as or different from each other.

Description

[Technical Field]

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

[0002] In recent years, various industries have been moving to reduce the use of organic solvents in order to improve working environments and protect the global environment. This has led to an increase in the use of aqueous-developable photopolymer plates in the platemaking process for photosensitive flexographic printing plates used in printing.

[0003] For example, Patent Document 1 describes an aqueous developer composition for photosensitive resins, which comprises "at least a surfactant (A), a pH adjuster (B), a cleaning promoter (C), and water, wherein the surfactant (A) contains 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, and the pH of the aqueous developer is 8 to 13, and the cleaning promoter (C) contains a compound represented by the following formula (I) or (II): RO(AO) n R1 (I) C n H 2n+2 ··············(II) 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 from 1 to 5. In the above formula (II), n is 6 to 20." (Claim 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-317660 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have studied the aqueous developer described in Patent Document 1 and found that it has good developability. However, they have found that if this aqueous developer is used repeatedly for two or more developments, when the developer remaining on the printing plate or on the wall of the bath of the developing device is washed away (rinsed) with water, dispersed matter in the developer diluted with water aggregates and re-adheres to the printing plate, causing stains on the printed material and affecting the maintainability of the developing device.

[0006] Therefore, an object of the present invention is to provide an aqueous developer for flexographic printing plates that maintains good developability and can suppress aggregation of dispersed matter in a developer diluted with water after repeated use, and a method for producing a flexographic printing plate using the same. [Means for solving the problem]

[0007] As a result of extensive research aimed at achieving the above object, the present inventors have found that an aqueous developer containing a nonionic surfactant having a predetermined structure can maintain good developability and inhibit aggregation of dispersed matter in a developer diluted with water after repeated use, thereby completing the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0008] [1] An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1) and water: R 1 O-(AO) n -H (1) Here, in the above formula (1), R 1 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, multiple As may be the same or different.

[0009] [2] The aqueous developer for flexographic printing plates according to [1], wherein n in the formula (1) represents an integer of 10 or more. [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 more. [4] R in the above formula (1) 1 The aqueous developer for flexographic printing plates according to any one of [1] to [3], wherein the compound (I) has an ethylenically unsaturated double bond. [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): R 2 -X (2) Here, in the above 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 sulfate group or a salt thereof, or a phosphate group or a salt thereof.

[0010] [6] A method for producing a flexographic printing plate having non-image areas and image areas, comprising: an exposure step of exposing a photosensitive layer of a flexographic printing plate precursor having a photosensitive layer to light in an imagewise manner; a development step in which, after the exposure step, the flexographic printing plate is developed using the aqueous developer for a flexographic printing plate according to any one of [1] to [5] to form non-image areas and image areas; A method for producing a flexographic printing plate, comprising a developing step followed by a rinsing step of rinsing with water. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an aqueous developer for flexographic printing plates that maintains good developability and can suppress aggregation of dispersed matter in a developer diluted with water after repeated use, and a method for producing a flexographic printing plate using the same. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits. In addition, in this specification, each component may be a substance corresponding to the component, and may be used alone or in combination of two or more. Here, when two or more 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.

[0013] [Aqueous developer for flexo printing plates] 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 that contains a nonionic surfactant represented by formula (1) described below (hereinafter also referred to as "the specific surfactant") and water.

[0014] In the present invention, as described above, the aqueous developer containing the specific surfactant can maintain good developability and can suppress aggregation of dispersed matter in the developer diluted with water after repeated use. Although the details of this are not clear, the present inventors speculate as follows. First, an aqueous developer is usually used repeatedly for two or more developments. 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, as a dispersion. Therefore, in the present invention, by incorporating a specific surfactant, the specific surfactant and the dispersion are adsorbed, and it is believed that the adsorption state can be maintained even when the dispersion is diluted with water in anticipation of the rinsing step. Specifically, in formula (1) described below, R 1 It is believed that the linear aliphatic hydrocarbon group represented by has 9 to 30 carbon atoms, which improves the affinity with the dispersion, allowing the adsorption state to be maintained even when diluted with water. Furthermore, in formula (1) described below, when n is an integer of 7 or more, the alkylene oxide becomes large, and as a result, the steric repulsion between the dispersed substances becomes large, which is thought to have suppressed aggregation of the dispersed substances. Each component contained in the aqueous developer of the present invention will be described in detail below.

[0015] [Specific surfactant] The specific surfactant contained in the aqueous developer of the present invention is a nonionic surfactant represented by the following formula (1). R 1 O-(AO) n -H (1) Here, in the above formula (1), R 1 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, multiple As may be the same or different.

[0016] R in the above formula (1) 1 Examples of the linear aliphatic hydrocarbon group having 9 to 30 carbon atoms represented by include an alkyl group, an alkenyl group, and an alkynyl group. 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 valence may be on an unsaturated carbon atom or on a saturated carbon atom. An alkynyl group refers to a monovalent group formed by removing one hydrogen atom from any carbon atom of an alkyne, and the free valence may be on an unsaturated carbon atom or on a saturated carbon atom.

[0017] 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. Specific examples of the alkenyl group include a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, and an octadecenyl group. Specific examples of the alkynyl group include a nonynyl group, a decynyl group, an undecynyl group, a dodecynyl group, a tridecynyl group, a tetradecynyl group, a pentadecynyl group, a hexadecynyl group, a heptadecynyl group, and an octadecynyl group.

[0018] Also, R 1 The linear aliphatic hydrocarbon group represented by has 9 to 30 carbon atoms, preferably 10 to 20 carbon atoms, and more preferably 12 to 18 carbon atoms.

[0019] In the present invention, the aggregation of the dispersion can be further suppressed by changing the R 1 Preferably, the alkylene group has an ethylenically unsaturated double bond (carbon-carbon double bond), and more preferably has one carbon-carbon double bond.

[0020] A in the above formula (1) 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.

[0021] In the above formula (1), n represents an integer of 7 or more, but is preferably an integer of 10 or more, and more preferably an integer of 15 or more, because this allows for better suppression of aggregation of the dispersion. 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.

[0022] In the present invention, because aggregation of the dispersion can be further suppressed, the HLB (Hydrophile-Lipophile Balance) value of the specific surfactant is preferably 10 to 17, and more preferably 12 to 15. When the HLB value is 10 to 17, the solubility of the specific surfactant in water is appropriately suppressed, allowing the formation of a stable emulsion (suspension), which is thought to further suppress aggregation of the dispersion. Here, the HLB value is determined by the Griffin formula. In the Griffin formula, the HLB value is calculated according to the following formula using the value of S (saponification value of the ester) and the value of N (neutralization value of the fatty acid that constitutes the ester). 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. HLB value = 20(1-S / N)

[0023] Specific examples of the specific surfactant include polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether.

[0024] 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.

[0025] 〔water〕 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. Milli-Q water is ultrapure water obtained using a Milli-Q water production system, an ultrapure water production system manufactured by Merck Ltd. The content of water contained in the aqueous developer of the present invention is preferably from 80 to 99.99% by mass, more preferably from 90 to 99.9% by mass, based on the total mass of the aqueous developer.

[0026] [Anionic surfactants] The aqueous developer of the present invention preferably contains an anionic surfactant represented by the following formula (2), because this improves the developability and improves the stability of the concentrated aqueous developer. R 2 -X (2) Here, in the above 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 sulfate group or a salt thereof, or a phosphate group or a salt thereof.

[0027] R in the above formula (2) 2 Examples of the aliphatic hydrocarbon group having 7 to 15 carbon atoms represented by include an alkyl group, an alkenyl group, and an alkynyl group. Specific examples of the alkyl group include linear alkyl groups such as octyl, nonyl, decyl, dodecyl, and tetradecyl groups; and branched alkyl groups such as isooctyl, 2-ethylhexyl, isodecyl, isododecyl, and isotetradecyl groups. Specific examples of the alkenyl group include a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, and a pentadecenyl group. Specific examples of the alkynyl group include a heptynyl group, an octynyl group, a nonynyl group, a decynyl group, an undecynyl group, a dodecynyl group, a tridecynyl group, a tetradecynyl group, and a pentadecynyl group.

[0028] 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 sulfate group (-OSO3H) or a salt thereof, or a phosphate group (-OPO3H2) or a salt thereof, and among these, a carboxylic acid group (-COOH) or a salt thereof, a sulfonic acid group or a salt thereof, or a sulfate group or a salt thereof is preferred, and a carboxylic acid group or a salt thereof is more preferred. 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.

[0029] Specific examples of the anionic surfactant represented by the above formula (2) include sodium laurate, potassium laurate, sodium oleate, and potassium palmitate.

[0030] In the present invention, when the anionic surfactant represented by the above formula (2) is contained, the content thereof 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.

[0031] [Alkaline agent] The aqueous developer of the present invention preferably contains an alkaline agent because this improves the developability. Examples of the alkaline agent include alkali metal carbonates and alkali metal hydroxides. Specific examples of alkali metals include sodium, potassium, and calcium. Specific examples of alkali metal carbonates include sodium carbonate and potassium carbonate, with sodium carbonate being preferred from the standpoint of safety. Specific examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide.

[0032] When an alkaline agent is contained, the content thereof is preferably from 0.01 to 5% by mass, more preferably from 0.05 to 3% by mass, based on the total mass of the aqueous developer.

[0033] [Chelating Agent] The aqueous developer of the present invention preferably contains a chelating agent, since this can further suppress aggregation of the dispersed matter. 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.

[0034] [Other ingredients] The aqueous developer of the present invention may contain various additives as optional components, if necessary. Examples of additives that can be appropriately blended include alkanolamines such as ethanolamine; preservatives such as benzotriazole and benzoic acid; freezing point depressants such as glycols (e.g., ethylene glycol) and lower alcohols (e.g., ethanol); and antifoaming agents such as silicones and polyols, within a range that does not impair the effects of the present invention.

[0035] [Developing method] The developing method using the aqueous developer of the present invention may be the same as a developing method using a conventionally known aqueous developer, and may include, for example, a method in which the aqueous developer is brought into contact with the unexposed area of a flexographic printing plate precursor, and a physical action such as a brush, water pressure, or ultrasonic waves is applied to disperse the photosensitive layer (photosensitive resin composition) constituting the unexposed area in the aqueous developer and remove it. In this case, the unexposed area may be immersed in the aqueous developer, or may be continuously supplied to be in contact with the unexposed area when the physical action is exerted. The aqueous developer preferably has a liquid temperature of 20 to 60°C, more preferably 30 to 50°C, during development. Furthermore, as a commonly used physical force, a brush is used, and the material, thickness, length, density, arrangement, movement and rotation direction of the bristles are appropriately selected.

[0036] [Flexographic printing plate precursor] The photosensitive layer (photosensitive resin composition) of the flexographic printing plate precursor to be developed with the aqueous developer of the present invention may be a conventionally known photosensitive resin composition, and examples thereof include resin compositions containing a water-dispersible latex, rubber, a photopolymerizable monomer, a photopolymerization initiator, a surfactant, etc.

[0037] <Water-dispersible latex> The water-dispersed latex contained in the resin composition is not particularly limited, and any water-dispersed latex that has been used in conventionally known flexographic printing plates can be used. 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, thiokol polymer latex, and acrylate polymer latex; and 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.

[0038] <Rubber> The rubber contained in the resin composition is not particularly limited, and any rubber material that has been used in conventionally known flexographic printing plates can be used. Specific examples of the rubber include butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, urethane 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.

[0039] <Photopolymerizable monomer> The photopolymerizable monomer contained in the resin composition is not particularly limited, and any photopolymerizable monomer used in conventionally known flexographic printing plates can be used. The photopolymerizable monomer may include, for example, an ethylenically unsaturated compound. Specific examples of the ethylenically unsaturated compound include (meth)acrylic monomers, (meth)acrylic oligomers, and (meth)acrylic modified polymers. Specific examples of the (meth)acrylic modified polymer include (meth)acrylic modified butadiene rubber and (meth)acrylic modified nitrile rubber. The term "(meth)acrylic" refers to either acrylic or methacrylic.

[0040] <Photopolymerization initiator> The photopolymerization initiator contained in the resin composition is not particularly limited as long as it initiates photopolymerization of the above-mentioned photopolymerizable monomer, and examples thereof include photopolymerization initiators such as alkylphenones, acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzils, and biacetyls. Specific examples include benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methyl-o-benzoylbenzoate, and 1-hydroxycyclohexyl phenyl ketone.

[0041] <Surfactant> The resin composition preferably contains a surfactant from the viewpoint of improving water developability. The surfactant may be a cationic surfactant, an anionic surfactant, or a nonionic surfactant, with anionic surfactants being preferred.

[0042] Specific examples of the anionic surfactant include: aliphatic carboxylates such as sodium laurate and sodium oleate; higher alcohol sulfates such as sodium lauryl sulfate, sodium cetyl sulfate, and sodium oleyl sulfate; Polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate; Polyoxyethylene alkyl allyl ether sulfates such as sodium polyoxyethylene octylphenyl ether sulfate and sodium polyoxyethylene nonylphenyl ether sulfate; alkyl sulfonates such as alkyl diphenyl ether disulfonates, sodium dodecyl sulfonate, and sodium dialkyl sulfosuccinate; alkyl aryl sulfonates such as alkyl disulfonates, sodium dodecylbenzenesulfonate, sodium dibutylnaphthalenesulfonate, and sodium triisopropylnaphthalenesulfonate; higher alcohol phosphate ester salts such as disodium lauryl phosphate monoester and sodium lauryl phosphate diester; Polyoxyethylene alkyl ether phosphate ester salts such as polyoxyethylene lauryl ether phosphate monoester disodium and polyoxyethylene lauryl ether phosphate diester sodium; These may be used alone or in combination of two or more.

[0043] [Flexographic printing plate manufacturing method] The method for producing a flexographic printing plate of the present invention includes an exposure step of imagewise exposing a photosensitive layer of a flexographic printing plate precursor having a photosensitive layer, a development step of developing the resulting plate using the aqueous developer for flexographic printing plates of the present invention described above to form non-image areas and image areas, and a rinsing step of rinsing the resulting plate using water after the development step.

[0044] [Exposure process] The exposure step is a step in which the photosensitive layer is imagewise irradiated with actinic rays, thereby inducing crosslinking and / or polymerization in the areas irradiated with the actinic rays, and thereby hardening the layer.

[0045] The exposure step can be carried out by exposing through a mask provided on the outer surface side of the photosensitive layer. It is also preferable to use a vacuum frame exposure device. In this case, the exposure is carried out with actinic rays after the air between the relief-forming layer and the mask has been evacuated. Furthermore, the exposure may be carried out under conditions in which the oxygen concentration is reduced or in the atmosphere, and is not particularly limited. However, from the viewpoint of preventing inhibition of polymerization by oxygen, it is preferable to carry out the exposure under conditions in which the oxygen concentration is low.

[0046] [Development process] The developing step is a step of developing using the aqueous developer of the present invention described above to form non-image areas and image areas, and is as described in detail in the developing method using the aqueous developer of the present invention described above.

[0047] [Rinse process] The rinsing step is a step of rinsing the surfaces of the non-image areas and image areas formed in the developing step with water. In the present invention, the developer remaining on the surfaces of the non-image areas and the image areas is the aqueous developer of the present invention described above, and therefore adhesion and aggregation of dispersed matter in the developer can be suppressed even when the aqueous developer is diluted with water used in the rinsing step.

[0048] Examples of rinsing means in the rinsing step include a method of washing with tap water, a method of spraying high-pressure water, and a method of brushing the surfaces of the non-image areas and image areas mainly in the presence of water using a batch-type or conveying-type brush-type washing machine known as a developing machine for flexographic printing plates.

[0049] [Application] 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 surfaces of the bath of a developing apparatus. [Example]

[0050] 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 changed as appropriate 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.

[0051] [Synthesis of nonionic surfactant CW-1] Potassium hydroxide was added to octanol to a concentration of 1% by mass, and then 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.

[0052] [Examples 1 to 7 and Comparative Examples 1 to 5] An aqueous developer was prepared by blending water, an alkaline agent, a nonionic surfactant, and an anionic surfactant in the parts by mass shown in Table 1 below.

[0053] 〔evaluation〕 <Developability> The cover film of a flexographic printing plate precursor (FLENEX FW-L2, Fujifilm Corporation) was peeled off, and the substrate side was exposed for 2 seconds (back exposure) from a distance of 15 cm using an exposure device equipped with 15 40 W chemical lamps. Thereafter, development was carried out for 3 minutes in a brush-type washing machine (liquid temperature 50° C.) containing each of the prepared aqueous developers. The plate was then dried with hot air at 60°C until all moisture was removed. The thickness of the resulting flexographic printing plate was measured using a constant pressure thickness gauge, and the change in film thickness per minute (development rate) was calculated from the change in thickness before and after development. The plate was then evaluated according to the following criteria. The results are shown in Table 1 below. In practical terms, a rating of B or higher is preferable. (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

[0054] <Aggregation inhibition> The cover film of a flexographic printing plate precursor (FLENEX FW-L2, Fujifilm Corporation) was peeled off, and the substrate side was exposed for 2 seconds (back exposure) from a distance of 15 cm using an exposure device equipped with 15 40 W chemical lamps. Thereafter, development was carried out for an arbitrary time using a brush-type washer (liquid temperature 50°C) containing each of the prepared aqueous developers so that the solid content of the development residue (dispersion) would be 7.0 mass%. The solid content of the development residue was determined by measuring 2.0 g of the aqueous developer used (hereinafter also abbreviated as "fatigue liquid"), drying it at 95°C for 18 hours, and calculating the solid content % in the fatigue liquid from the change in weight before and after drying. Next, 50 cc of the fatigue liquid was added to a 1000 cc plastic container containing 450 cc of water, and after stirring, the container was left to stand for 12 hours. The aggregates in the liquid were visually observed and evaluated according to the following criteria. The results are shown in Table 1 below. (Evaluation criteria) A: No large aggregates that can be visually identified B: A small amount of large aggregates that can be seen with the naked eye C: A small number of large aggregates that can be seen with the naked eye D: Many large aggregates that can be seen with the naked eye

[0055] <Stability of concentrated solution> Each aqueous developer solution was concentrated 10 times and the state of dissolution was visually observed at room temperature (23°C) and evaluated according to the following criteria. The results are shown in Table 1 below. A rating of B or higher is acceptable for practical use. (Evaluation criteria) A: Colorless and transparent B: Cloudy C: Two-layer separation D: Insoluble precipitate

[0056] [Table 1]

[0057] The components used in Table 1 above are as follows: Sodium carbonate: a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Emulgen 108: Polyoxyethylene lauryl ether (HLB: 12.0, manufactured by Kao Corporation) Paionin D-1115: Polyoxyethylene lauryl ether (Takemoto Oil Co., Ltd.) Paionin D-1315: Polyoxyethylene cetyl ether (Takemoto Oil & Fat Co., Ltd.) Paionin D-1323: Polyoxyethylene cetyl ether (Takemoto Oil Co., Ltd.) Paionin D-1420: Polyoxyethylene stearyl ether (Takemoto Oil Co., Ltd.) Paionin D-1518: Polyoxyethylene oleyl ether (Takemoto Oil Co., Ltd.) Paionin D-1004: Polyoxyethylene octyl ether (Takemoto Oil Co., Ltd.) Paionin D-1007: Polyoxyethylene octyl ether (Takemoto Oil Co., Ltd.) CW-1: The above-mentioned synthetic product Emulgen 104P: Polyoxyethylene lauryl ether (HLB: 9.7, manufactured by Kao Corporation) Polyoxyethylene (4) stearyl ether: a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sodium laurate: a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0058] As shown in Table 1 above, R in the above formula (1) 1 It was found that when n is an aliphatic hydrocarbon group having 8 carbon atoms, aggregation of development residue cannot be suppressed regardless of the value of n in the above formula (1) (Comparative Examples 1 to 3). In addition, R in the above formula (1) 1 Even if n is a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms, if n in the above formula (1) is an integer less than 7, it was found that aggregation of development residue could not be suppressed and the stability of the concentrate was also poor (Comparative Examples 4 to 5). In contrast to this, it was found that when a specific surfactant was added, good developability was maintained and aggregation of development residues could be suppressed (Examples 1 to 7). In particular, a comparison between Example 3 and Example 7 revealed that the incorporation of the anionic surfactant represented by the above formula (2) resulted in better developability and improved stability of the concentrated aqueous developer. Furthermore, by comparing Example 5 and Example 6, it was found that R 1 However, it was found that if the toner has an ethylenically unsaturated double bond (carbon-carbon double bond), the aggregation of development residue in the fatigue solution can be further suppressed.

Claims

1. An aqueous developer for flexographic printing plates, 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 linear aliphatic hydrocarbon group having 16 to 30 carbon atoms. A represents an alkylene group having 2 to 4 carbon atoms. n represents 15, and when n is an integer of 2 or more, multiple As may be the same or different.

2. An aqueous developer for flexographic printing plates, 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 linear aliphatic hydrocarbon group having 9 to 17 carbon atoms. A represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 15 or more and 20 or less, and when n is an integer of 2 or more, multiple As may be the same or different from each other.

3. An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1) and water, and further comprising an anionic surfactant represented by the following formula (2): R １ O-(AO) ｎ -H ・・・(1) Here, in the formula (1), R １ represents a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms and having an ethylenically unsaturated double bond. A represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 15 or more, and when n is an integer of 2 or more, multiple As may be the same or different. 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 sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

4. An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1) and water, and further comprising an anionic surfactant represented by the following formula (2): R １ O-(AO) ｎ -H ・・・(1) Here, in the formula (1), R １ 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 15 or more, and when n is an integer of 2 or more, multiple As may be the same or different. 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 sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

5. R in the formula (1) １ The aqueous developer for flexographic printing plates according to any one of claims 1 to 2 and 4, wherein

6. 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 sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

7. An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1) and water, and further comprising 0.01 to 5% by mass of an alkaline agent, excluding developers containing 0.5% by mass of potassium oleate: R １ O-(AO) ｎ -H ・・・(1) Here, in the formula (1), R １ represents a linear aliphatic hydrocarbon group having 16 to 30 carbon atoms. A represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 7 or more and 15 or less, and when n is an integer of 2 or more, multiple As may be the same or different from each other.

8. An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1), water, an anionic surfactant represented by the following formula (2), and 0.01 to 5% by mass of an alkaline agent, except for developers containing 0.5% by mass of potassium oleate: R １ O-(AO) ｎ -H ・・・(1) Here, in the formula (1), R １ represents a linear aliphatic hydrocarbon group having 9 to 30 carbon atoms and having an ethylenically unsaturated double bond. 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, multiple As may be the same or different. 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 sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

9. An aqueous developer for flexographic printing plates, comprising a nonionic surfactant represented by the following formula (1), water, an anionic surfactant represented by the following formula (2), and 0.01 to 5% by mass of an alkaline agent, except for developers containing 0.5% by mass of potassium oleate: R １ O-(AO) ｎ -H ・・・(1) Here, in the formula (1), R １ 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, multiple As may be the same or different. 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 sulfate group or a salt thereof, or a phosphoric acid group or a salt thereof.

10. The aqueous developer for flexographic printing plates according to any one of claims 7 to 9, wherein the alkaline agent is any one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

11. 1. A method for producing a flexographic printing plate having non-image areas and image areas, comprising: an exposure step of exposing a photosensitive layer of a flexographic printing plate precursor having the photosensitive layer to light in an imagewise manner; a developing step of developing the flexographic printing plate using the aqueous developer for flexographic printing plates according to any one of claims 1 to 10 after the exposure step to form non-image areas and image areas; a rinsing step of rinsing with water after the developing step.

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