Flexographic printing original plate and method for manufacturing flexographic printing plate

Abstract

A flexographic printing original plate in which at least a support body (a), a photosensitive resin composition layer (b), and an infrared ablative layer (c) are laminated, the flexographic printing original plate being characterized in that: the thickness of a 0.5 mm molded body of a photosensitive resin composition constituting the photosensitive resin composition layer (b) is 0.5 mm; when light differential scanning calorimetry is performed while irradiating light having a wavelength of 365 nm and an illuminance of 10 mW / cm2 under normal temperature and pressure, the time from the start of irradiation to the exothermic peak is 4.0-8.5 seconds, inclusive, and the amount of exothermic heat at the peak top is 1500-3000 [mu] W / mg, inclusive.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing a flexographic printing plate and a flexographic printing plate. BACKGROUND

[0002] Flexographic printing is a printing method in which ink is carried on a relief portion of a flexographic printing plate and the flexographic printing plate is pressed against a printing object to transfer the ink from the flexographic printing plate to the printing object.

[0003] A flexographic printing plate used in flexographic printing is generally manufactured using a flexographic printing plate precursor in which a photosensitive resin composition layer is layered on a polyester film serving as a support.

[0004] As a method for manufacturing a flexographic printing plate from a flexographic printing plate precursor, for example, the following method can be cited.

[0005] First, the entire surface of the photosensitive resin composition layer is subjected to ultraviolet exposure (back exposure) through the polyester film serving as a support to provide a thin and uniform cured layer. Next, a negative is arranged on the photosensitive resin composition layer, and the photosensitive resin composition layer is subjected to image exposure (relief exposure) through the negative to cause photocuring of the photosensitive resin composition layer according to the pattern of the negative. Thereafter, the unexposed portion (i.e., the uncured portion) of the photosensitive resin composition layer is washed with a developing solution to form a desired image, i.e., a relief image, thereby obtaining a flexographic printing plate.

[0006] In recent years, instead of the above-described method using a negative, a technique in which an ablation layer capable of being cut by infrared laser is provided on a photosensitive resin composition layer, the ablation layer is cut into a desired pattern by laser, and then exposure is performed to set a portion to be subjected to ultraviolet curing and a portion not to be subjected to ultraviolet curing, i.e., so-called digital plate making technique, is becoming widespread.

[0007] The above-described digital plate making technique has the following advantages over the conventional analog plate making technique using a negative: time and labor for negative making can be saved, and furthermore, a higher-fineness image can be produced.

[0008] On the other hand, as a problem of the digital plate making technique, there is a problem of formation failure of a flexographic printing plate due to oxygen inhibition of the curing reaction of the photosensitive resin, i.e., so-called oxygen inhibition. In particular, in a minute dot portion called high light, a dot having a shape in which the edge of the relief formed due to the influence of oxygen inhibition has a curvature, i.e., a dome dot, and thus, the boundary between the printed portion and the non-printed portion becomes unclear, and the printing quality is greatly reduced due to a slight difference in printing conditions. In addition, the above-described dome dot has the following problem: the dot size easily becomes large due to abrasion of the dot with an increase in the number of printing, and thus, it is difficult to maintain a bright dot image before and after printing.

[0009] In recent years, if the situation is taken into consideration that higher precision and brighter, high-resolution printing quality is required for flexible printing, a digital plate making technology is required in which the boundary between a printed portion and a non-printed portion is clear and the dot size of the beginning and end of printing does not easily change, and a flat-top dot, that is, a dot having a flat top portion, is formed.

[0010] In view of the above-described problems, a technology has been known in which a high-intensity exposure machine using an LED or the like is used to increase the speed of the curing reaction of the surface of a flexible printing plate compared to the poor curing caused by the influence of oxygen hindrance. It can be considered that, with the development of high-intensity exposure machines, such a technology will increasingly become mainstream in the future, and high-intensity exposure machines will gradually become widespread.

[0011] On the other hand, a device into which a high-intensity exposure machine is introduced incurs costs, and therefore, many must use a low-intensity exposure machine using a high-pressure mercury lamp or the like as in the past. In order to form a flat-top dot using a low-intensity exposure machine, a technology for making a flexible printing plate by reducing the influence of oxygen hindrance by disposing an oxygen barrier film between a laser ablation layer and a photosensitive resin composition layer is proposed in Patent Literature 1, for example.

[0012] In addition, a technology for making a flexible printing plate by increasing the sensitivity of a photosensitive resin composition layer is proposed in Patent Literature 2.

[0013] Prior Art Documents

[0014] Patent Literature

[0015] Patent Literature 1: Japanese Patent Application Laid-Open No. 10-509254

[0016] Patent Literature 2: Japanese Patent Application Laid-Open No. 2015-529345 SUMMARY

[0017] PROBLEMS TO BE SOLVED BY THE INVENTION

[0018] However, a flexible printing plate made by the technologies disclosed in Patent Literatures 1 and 2 forms a flat-top dot having a proper size and shape when plate making is performed using a low-intensity exposure machine, but has problems in which an intermediate style dot is excessively formed, the dot size becomes large, and an image becomes dark at the time of printing, if plate making is performed using a high-intensity exposure machine. Therefore, in the digital plate making technology, there is a problem in which it is necessary to distinguish the use of a flexible printing plate depending on the intensity of an exposure machine, and the operation becomes complicated.

[0019] Today, exposure machines having different intensities are mixed on the market, and from the viewpoint of level integration, development of a flexible printing plate manufacturing technology in which a flat-top dot having a proper size can be formed using an exposure machine having any intensity is an important issue.

[0020] Thus, an object of the present application is to provide a flexographic printing precursor which is excellent in dot formation when plate-making by low-intensity exposure and which can suppress excessive formation of intermediate-style dots when plate-making by high-intensity exposure.

[0021] Solution to the problem

[0022] The present inventors have conducted intensive studies in order to solve the above problem, and as a result, have found that the above problem can be solved by determining the time from irradiation to the exothermic peak and the exothermic amount at the peak top when a photosensitive resin composition layer is measured by photo-differential scanning calorimetry (photo-DSC) to be within a prescribed numerical range, thereby completing the present application.

[0023] That is, the present application is as follows.

[0024] 〔1〕

[0025] A flexographic printing precursor which is a flexographic printing precursor in which at least a support (a), a photosensitive resin composition layer (b), and an infrared ablation layer (c) are layered,

[0026] When a 0.5-mm-thick molded body of the photosensitive resin composition which constitutes the aforementioned photosensitive resin composition layer (b) is subjected to photo-differential scanning calorimetry under normal temperature and pressure while irradiating light having a wavelength of 365 nm at an intensity of 10 mW / cm 2 2, the time from the start of irradiation to the exothermic peak is 4.0 seconds or more and 8.5 seconds or less, and the exothermic amount at the peak top is 1500 μW / mg or more and 3000 μW / mg or less.

[0027] 〔2〕

[0028] The flexographic printing precursor according to the aforementioned item [1], wherein the aforementioned photosensitive resin composition layer (b) contains at least one or more selected from the group consisting of an ethylenically unsaturated compound (b-2), a photopolymerization initiator (b-3), a stabilizer (b-5), and a dye (b-6).

[0029] 〔3〕

[0030] The flexographic printing precursor according to the aforementioned item [2], wherein the aforementioned dye (b-6) contains a dye (B-6) having a 1,4-diamino-5,8-dihydroxyanthraquinone skeleton in the molecular structure.

[0031] 〔4〕

[0032] The flexographic printing precursor according to the aforementioned item [3], wherein the aforementioned dye (B-6) has a molecular structure represented by the following formula (1).

[0033]

[0034] In formula (1), R1, R2 each independently represents an alkyl group having 1 to 4 carbon atoms.

[0035] 〔5〕

[0036] The flexible printing original according to the aforementioned [4], wherein the dye having the molecular structure represented by the aforementioned formula (1) is contained in the aforementioned photosensitive resin composition layer (b) in an amount of 0.005 mass% or more and 0.1 mass% or less.

[0037] 〔6〕

[0038] The flexible printing original according to any one of the aforementioned [2] to [5], wherein, as the aforementioned stabilizer (b-5), at least one stabilizer (B-5) is contained, the stabilizer (B-5) being a compound represented by the following formula (2) or (3),

[0039] The content of the aforementioned stabilizer (B-5) is 0.45 mass% or less of the photosensitive resin composition layer (b).

[0040]

[0041]

[0042] In formula (2), (3), R3, R5 each independently represents an alkyl group having 1 to 4 carbon atoms. R4, R6 each independently represents an alkyl group having 1 to 12 carbon atoms.

[0043] 〔7〕

[0044] The flexible printing original according to the aforementioned [6], wherein the content of the aforementioned stabilizer (B-5) is 60 mass% or more and 100 mass% or less with respect to the total amount of the aforementioned stabilizer (b-5).

[0045] 〔8〕

[0046] The flexible printing original according to any one of the aforementioned [2] to [5], wherein, as the aforementioned ethylenically unsaturated compound (b-2), an ethylenically unsaturated compound (B-2) having the structure represented by the following formula (4) is contained.

[0047]

[0048] In formula (4), R7, R8, and R9 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. * represents a bond.

[0049] 〔9〕

[0050] According to the aforementioned flexible printing original [8], the aforementioned olefinic unsaturated compound (B-2) comprises the compound shown in the following formula (5).

[0051]

[0052]

[10]

[0053] A method for manufacturing a flexographic printing plate, which uses any one of the flexographic printing plates described in any one of [1] to [8] above, the method comprising the following steps:

[0054] In the first step, ultraviolet light is irradiated from the aforementioned support (a) side;

[0055] The second step involves laser ablation of the infrared ablation layer (c) disposed on the aforementioned photosensitive resin composition layer (b) to create a negative pattern.

[0056] The second step involves using the aforementioned infrared ablation layer (c), on which the aforementioned pattern has been applied, as a mask to expose the aforementioned photosensitive resin composition layer (b) to ultraviolet light; and

[0057] The fourth step involves removing the unexposed portion of the aforementioned photosensitive resin composition layer (b).

[0058]

[11] In the method for manufacturing a flexible printing plate as described in

[10] above, solvent development is performed in the fourth step of removing the unexposed portion of the aforementioned photosensitive resin composition layer (b).

[0059]

[12] In the method for manufacturing a flexible printing plate as described in

[10] above, thermal development is performed in the fourth step of removing the unexposed portion of the aforementioned photosensitive resin composition layer (b).

[0060] The effects of the invention

[0061] According to the present invention, a flexible printing master plate capable of obtaining a flexible printing plate can be provided, wherein the flexible printing plate can form flat-top dots even at highlight dots when exposed to low light, and can suppress the excessive formation of intermediate style dots when exposed to high light. Attached Figure Description

[0062] Figure 1 This is a schematic cross-sectional view of the flexographic printing original of this embodiment.

[0063] Figure 2 This is a schematic diagram illustrating a method for manufacturing a flexographic printing plate using the flexographic printing master of this embodiment.

[0064] Figure 3is a graph showing the exothermic behavior when the light DSC of the photosensitive resin composition layer (b) in the flexible printing master of Example 4 was measured. DETAILED DESCRIPTION

[0065] Hereinafter, a mode for carrying out the present application (hereinafter referred to as "the present embodiment") will be described in detail.

[0066] Note that the present embodiment below is an example for illustrating the present application and does not mean that the present application is limited to the following content. The present application can be carried out in various modifications within the scope of the gist thereof.

[0067] 〔Flexible printing master〕

[0068] The flexible printing master of the present embodiment is at least composed of a support (a), a photosensitive resin composition layer (b), and an infrared ablation layer (c).

[0069] When a 0.5 mm-thick molded body of the photosensitive resin composition constituting the aforementioned photosensitive resin composition layer (b) was subjected to photodifferential scanning calorimetry (hereinafter sometimes referred to as measurement based on light DSC) under air, that is, at normal temperature (about 25°C) and normal pressure, while irradiating light of a wavelength of 365 nm at an irradiance of 10 mW / cm 2 , the time from the start of irradiation to the exothermic peak was 4.0 seconds or more and 8.5 seconds or less, and the exothermic amount at the peak top was 1500 μW / mg or more and 3000 μW / mg or less.

[0070] By having the above constitution, it is possible to provide a flexible printing master from which a flexible printing plate can be obtained, which is capable of forming flat dots even at a high dot area when low-intensity exposure is performed, and which is capable of suppressing the excessive formation of intermediate-style dots when high-intensity exposure is performed.

[0071] Note that in the present specification, low-intensity exposure refers to exposure under which the irradiance of light of 365 nm is 15 mW / cm 2 or less, and high-intensity exposure refers to exposure under which the irradiance of light of 365 nm is 50 mW / cm 2 or more. The exposure machine used under various exposure conditions is not limited.

[0072] Figure 1 A schematic cross-sectional view of the flexible printing master 1 of the present embodiment is shown in FIG. 1.

[0073] The flexible printing master of the present embodiment has a support (a) and a photosensitive resin composition layer (b) in which a relief pattern of a flexible printing plate is to be formed.

[0074] In addition, the flexible printing original 1 of the present embodiment can have, as needed, a protective layer (see, for example, Japanese Patent No. 5-13305) having a function of improving contactability with a prescribed negative film, having solvent solubility, and being light and flexible.

[0075] Figure 1 In the flexible printing original of the present embodiment, an infrared ablation layer (c) that functions as a mask when forming the aforementioned concave-convex pattern is laminated on the photosensitive resin composition layer (b).

[0076] The flexible printing original of the present embodiment can further have other layers as needed between the respective layers.

[0077] Hereinafter, the flexible printing original of the present embodiment will be described.

[0078] (Support (a))

[0079] As the support (a) used in the flexible printing original of the present embodiment, there is no limitation, and examples include, for example, polyester films, polyamide films, polyacrylonitrile films, polyvinyl chloride films, and the like.

[0080] As the support (a), a polyester film is preferable.

[0081] As the polyester used in the support (a), there is no limitation to the following substances, and examples include, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like.

[0082] The thickness of the support (a) is not particularly limited, and is preferably 50 μm or more and 300 μm or less.

[0083] In addition, an adhesive layer can be provided on the support (a) for the purpose of improving the adhesion between the support (a) and the photosensitive resin composition layer (b) described later. As the aforementioned adhesive layer, there is no limitation to the following layers, and examples include, for example, the adhesive layer described in International Publication No. 2004 / 104701.

[0084] (Photosensitive resin composition layer (b))

[0085] As a result of intensive studies by the present inventors and the like, from the viewpoint of balancing the formability of high dot portions when performing low-intensity exposure and the suppression of excessive formation of intermediate-style dots when performing high-intensity exposure, attention was paid to the exothermic behavior of the photo DSC of the photosensitive resin composition layer (b) that constitutes the flexible printing original, and it was found that it is particularly important to control the time from the start of irradiation until reaching the exothermic peak and the exothermic amount at the peak top to a certain prescribed range.

[0086] The light DSC (Differential Scanning Calorimeter) is a device for performing light differential scanning calorimetry. In detail, it is a device for analyzing the light curing behavior by irradiating a photosensitive resin having ultraviolet curability with ultraviolet rays and measuring the reaction heat.

[0087] Figure 3 A graph showing the measurement results of the light DSC when a sample for the following Example 4 was irradiated with 365 nm light having an irradiance of 10 mW / cm 2

[0088] Figure 3 In the graph, the horizontal axis represents time (sec) and the vertical axis represents the heat release amount (μW / mg).

[0089] The horizontal axis sets the start of irradiation as 0 sec.

[0090] The heat release peak refers to the maximum value of the curve shown in Figure 3

[0091] The present inventors have found, as a result of intensive research, that by determining the reaction time of the light DSC and the reaction heat at the reaction peak to a certain prescribed range, it is possible to control the dot formation failure when low-intensity exposure is performed and the dot formation excess when high-intensity exposure is performed, respectively. In particular, when high-intensity exposure is performed, it is important to control the instantaneous heat release amount at the heat release peak at which the light curing reaction is most intense, rather than focusing on the total amount of reaction heat, as follows.

[0092] In detail, if a flexible printing original is exposed with low intensity, the radicals generated from the photoreaction initiator in the surface of the photosensitive resin composition layer are consumed by oxygen in the atmosphere, and therefore, the speed of the curing reaction becomes slow and the formability of the flexible printing plate decreases. Therefore, under low-intensity exposure conditions, how to suppress the influence of oxygen inhibition to the minimum becomes a key to improving the formability of the flexible printing plate. Shortening the time from the start of the light curing reaction to the reaction peak means increasing the reaction speed at the initial stage of the reaction, i.e., the start stage of the light curing reaction. Therefore, if the time from the start of light irradiation to the heat release peak is shortened, the reaction start speed increases and the influence of oxygen inhibition is suppressed, and therefore, the formability of the flexible printing plate under low-intensity exposure conditions is improved.

[0093] ​​On the other hand, when a flexible printing original plate is exposed to high-intensity light exposure, free radicals are generated by the photoreaction initiator, and the photocuring reaction is performed instantaneously, and thus, there is a tendency that the intermediate tone dots are formed excessively. Therefore, in order to suppress the excessive formation of the aforementioned intermediate tone dots, it is important to control the amount of free radicals at the time when the photocuring reaction is most intense. That is, in order to control the flexibility of the flexible printing plate when exposed using a high-intensity exposure machine, and to suppress the excessive formation of the intermediate tone dots, it is important to suppress the amount of heat release of the exothermic peak of the photo DSC to be below a predetermined value.

[0094] In order to exert the effects related to the excellent flexibility of the flexible printing plate described above, the photosensitive resin composition that constitutes the photosensitive resin composition layer (b) of the flexible printing original plate is molded to be 0.5 mm thick, and the measurement based on the photo DSC is performed while irradiating light having a wavelength of 365 nm at an intensity of 10 mW / cm 2 2, and the amount of heat release at the peak top must be 1500 to 3000 μW / mg, when the measurement based on the photo DSC is performed while irradiating light having a wavelength of 365 nm at an intensity of 10 mW / cm

[0095] Within the numerical range described above, there is a tendency that excellent flat tone dot formation is exhibited when exposed by both low-intensity exposure and high-intensity exposure.

[0096] If the time until the exothermic peak is 8.5 seconds or less, excellent high-light tone dot formation of the flexible printing original plate can be obtained even when exposed to low-intensity light.

[0097] In addition, if the amount of heat release at the peak top is 3000 μW / mg or less, excellent effects of suppressing the excessive formation of the intermediate tone dots can be obtained when exposed to high-intensity light.

[0098] From the viewpoint of balancing the excellent high-light tone dot formation in low-intensity exposure and the suppression of the excessive formation of the intermediate tone dots in high-intensity exposure, the time until the aforementioned exothermic peak is set to be 4.0 seconds or more and 8.5 seconds or less, preferably 5 seconds or more and 8.5 seconds or less, more preferably 7.1 seconds or more and 8.5 seconds or less, and further preferably 7.1 seconds or more and 8.3 seconds or less.

[0099] From the same viewpoint, the amount of heat release at the peak top is set to be 1500 μW / mg or more and 3000 μW / mg or less, preferably 1800 μW / mg or more and 3000 μW / mg or less, more preferably 1900 μW / mg or more and 2900 μW / mg or less, and further preferably 2000 μW / mg or more and 2800 μW / mg or less.

[0100] The time from the start of irradiation to the exothermic peak and the exothermic amount at the peak top in the differential scanning calorimetry described above can be controlled to the above numerical ranges by adjusting the constituent materials of the photosensitive resin composition layer (b).

[0101] Specifically, as the constituent materials of the photosensitive resin composition layer (b) described above, it is effective to use the ethylenically unsaturated compound (b-2), the photopolymerization initiator (b-3), the stabilizer (b-5), and the dye (b-6) described later, and to adjust the composition thereof.

[0102] For example, there is a tendency that the more the photopolymerization initiator (b-3) and the ethylenically unsaturated compound (b-2) are contained, the more the exothermic reaction proceeds rapidly, the time to the exothermic peak becomes shorter, and the exothermic amount at the peak top increases. It is considered that this is because the influence of oxygen inhibition is suppressed by increasing the reaction rate of the photopolymerization initiator (b-3) and the ethylenically unsaturated compound (b-2), and the reaction heat increases. On the other hand, there is a tendency that the more the stabilizer (b-5) and the dye (b-6) are contained, the longer the time to the exothermic peak, and the smaller the exothermic amount at the peak top. It is presumed that the dye absorbs ultraviolet rays, and the stabilizer suppresses overreaction, thereby suppressing the reaction rate of the radical reaction, and slowing down the exothermic occurrence time and the exothermic amount. Thus, in order to adjust the time to the exothermic peak and the exothermic amount at the peak top, it is effective to adjust the amounts of the ethylenically unsaturated compound (b-2), the photopolymerization initiator (b-3), the stabilizer (b-5), the dye (b-6), and the relative proportions of the components.

[0103] In the flexible printing original of the present embodiment, the photosensitive resin composition layer (b) is provided on the support (a).

[0104] The photosensitive resin composition layer (b) can be directly laminated on the support (a), or can be indirectly laminated with the aid of a prescribed adhesive layer.

[0105] As the material of the photosensitive resin composition layer (b), a photosensitive resin composition containing a thermoplastic elastomer (b-1), an ethylenically unsaturated compound (b-2), a photopolymerization initiator (b-3), a stabilizer (b-5), a dye (b-6), and a liquid diene (b-4) can be suitably exemplified. The photosensitive resin composition layer (b) contains at least one or more selected from the group consisting of them, and they can be suitably used in combination.

[0106] In addition, the photosensitive resin composition layer (b) can further contain an auxiliary additive component as needed.

[0107] Hereinafter, each component will be described in detail.

[0108] <Thermoplastic Elastomer (b-1)>

[0109] As the thermoplastic elastomer (b-1), not limited to the following substances, for example, a copolymer having a structural unit derived from a monovinyl-substituted aromatic hydrocarbon and a structural unit derived from a conjugated diene can be exemplified. Note that the thermoplastic elastomer (b-1) can further have a structural unit derived from another monomer. By using such a thermoplastic elastomer, there is a tendency that the print durability of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment is further improved.

[0110] The thermoplastic elastomer (b-1) can be a random copolymer or a block copolymer, and is preferably a block copolymer having a polymer block formed from a monovinyl-substituted aromatic hydrocarbon and a polymer block formed from a conjugated diene.

[0111] By using such a thermoplastic elastomer, there is a tendency that the print durability of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment is further improved.

[0112] As the monovinyl-substituted aromatic hydrocarbon constituting the thermoplastic elastomer (b-1), not limited to the following substances, for example, styrene, t-butylstyrene, 1,1-diphenyl ethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, p-methoxystyrene, t-butylstyrene, a-methylstyrene, 1,1-diphenyl ethylene, and the like can be exemplified. They can be used alone only one kind, or two or more kinds in combination.

[0113] Among them, from the viewpoint that the layer (b) of the photosensitive resin composition can be smoothly formed at a lower temperature, as the monovinyl-substituted aromatic hydrocarbon, styrene is preferred.

[0114] As the conjugated diene constituting the thermoplastic elastomer (b-1), not limited to the following substances, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chlorobutadiene, and the like can be exemplified.

[0115] They can be used alone only one kind, or two or more kinds in combination.

[0116] Among them, from the viewpoint of the print durability of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment, as the conjugated diene, 1,3-butadiene is preferred.

[0117] From the viewpoint of viscosity at room temperature, the number-average molecular weight (Mn) of the thermoplastic elastomer (b-1) is preferably 20,000 or more and 300,000 or less, more preferably 50,000 or more and 200,000 or less. The number-average molecular weight can be determined by gel permeation chromatography (GPC) and is expressed as the equivalent molecular weight of polystyrene.

[0118] When the thermoplastic elastomer (b-1) is a block copolymer having polymer blocks formed from monovinyl-substituted aromatic hydrocarbons and polymer blocks formed from conjugated dienes, the thermoplastic elastomer (b-1) includes, for example, linear block copolymers as shown in general formula (I) below and / or linear block copolymers or star-shaped block copolymers (RAZALUBLOCK copolymers) as shown in general formula (II) below.

[0119] General formula group (I):

[0120] (AB) n A- (BA) n A- (BA) n -B、B-(AB) n

[0121] General formula group (II):

[0122] [(AB)] k ] m -X、[(AB) k -A] m -X、[(BA) k ] m -X、[(BA) k -B] m -X

[0123] In general formula groups (I) and (II), A represents a polymer block formed by a monovinyl-substituted aromatic hydrocarbon. Additionally, B represents a polymer block formed by a conjugated diene. X represents a residue of a coupling agent selected from the group consisting of silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, polyhalogenated hydrocarbon compounds, carboxylic acid ester compounds, polyvinyl compounds, bisphenol-type epoxy compounds, alkoxysilane compounds, halosilane compounds, and ester compounds, or a residue of a polymerization initiator such as a polyfunctional organolithium compound.

[0124] In the general formula groups (I) and (II), n, k and m represent integers greater than 1, for example, 1 to 5.

[0125] The content of conjugated dienes and monovinyl substituted aromatic hydrocarbons in thermoplastic elastomer (b-1) can be determined using a nuclear magnetic resonance (NMR) device. 1 The determination was performed using H-NMR. Specifically, as 1The measurement device of H-NMR used JNM-LA400 (manufactured by JEOL Ltd., trade name), solvent used deuterated chloroform, sample concentration was set to 50 mg / mL, observation frequency was set to 400 MHz, chemical shift reference used TMS (tetramethylsilane), pulse delay was set to 2.904 seconds, number of scans was set to 64 times, pulse width was set to 45°, measurement temperature was set to 25°C, thereby enabling measurement.

[0126] In the thermoplastic elastomer (b-1), if the ratio of the monovinyl-substituted aromatic hydrocarbon is reduced, the hardness of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment is reduced, and thus the softness of the flexographic printing plate is improved. On the other hand, if the ratio of the monovinyl-substituted aromatic hydrocarbon is increased, the hardness of the flexographic printing plate is increased, and thus the print durability of the flexographic printing plate is improved. From the viewpoint of balancing the softness and the print durability of the flexographic printing plate, the copolymerization ratio (mass ratio) of the monovinyl-substituted aromatic hydrocarbon to the conjugated diene is preferably in the range of monovinyl-substituted aromatic hydrocarbon / conjugated diene = 10 / 90 to 60 / 40, more preferably in the range of 15 / 85 to 50 / 50, and further preferably in the range of 15 / 85 to 40 / 60.

[0127] In the thermoplastic elastomer (b-1), if the ratio of the double bonds in the polymer block formed from the conjugated diene, which are located in the side chain, is reduced, the loss elastic modulus G" at -30°C and 2.5 Hz of a cured product obtained by ultraviolet curing of an object in which the photosensitive resin composition layer (b) constituting the flexographic printing precursor of the present embodiment is formed into a thickness of 1.5 mm is reduced. Thus, from the viewpoint of controlling the dynamic viscoelasticity of the photosensitive resin composition of the photosensitive resin composition layer (b) constituting the flexographic printing precursor, the molar ratio of the amount of the double bonds in the polymer block formed from the conjugated diene, which are located in the side chain, to the total amount of the double bonds in the polymer block formed from the conjugated diene is preferably 3 mol% or more and 30 mol% or less, and more preferably 3 mol% or more and 25 mol% or less.

[0128] The ratio of the amount of the double bonds included in the main chain of the polymer block formed from the conjugated diene to the amount of the double bonds included in the side chain in the thermoplastic elastomer (b-1) can be calculated using the above-described nuclear magnetic resonance device (H-NMR). 1 H-NMR.

[0129] By increasing the content of the thermoplastic elastomer (b-1) in the photosensitive resin composition layer (b), there is a tendency that the print durability of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment is improved. On the other hand, if the content of the thermoplastic elastomer (b-1) in the photosensitive resin composition (b) is reduced, the hardness of the flexographic printing plate is reduced, and thus the softness of the flexographic printing plate is improved. From the viewpoint of balancing the print durability and the softness of the flexographic printing plate, when the total amount of the photosensitive resin composition layer (b) is 100.0% by mass, the content of the thermoplastic elastomer (b-1) in the photosensitive resin composition layer (b) is preferably 40.0% by mass or more and 80.0% by mass or less, and more preferably 50.0% by mass or more and 75.0% by mass or less.

[0130] <olefinically unsaturated compound (b-2)>

[0131] As described above, the photosensitive resin composition layer (b) preferably contains an olefinically unsaturated compound (b-2). The olefinically unsaturated compound (b-2) refers to a compound having an unsaturated double bond capable of undergoing radical polymerization.

[0132] In the photosensitive resin composition for a flexographic printing precursor of the present embodiment, as the olefinically unsaturated compound (b-2), an olefinically unsaturated compound having a structure represented by the following formula (4) (hereinafter sometimes referred to as an olefinically unsaturated compound (B-2)) is preferably contained.

[0133] The aforementioned olefinically unsaturated compound (B-2) can be a part of the aforementioned olefinically unsaturated compound (b-2), or can be all of the aforementioned olefinically unsaturated compound (b-2).

[0134]

[0135] In formula (4), R7, R8, and R9 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. * represents a bonding site.

[0136] In the photosensitive resin composition for a flexographic printing precursor of the present embodiment, by containing the olefinically unsaturated compound (B-2) having the specific structure represented by the aforementioned formula (4), there is a tendency that the influence of oxygen inhibition at the surface of the flexographic printing precursor is suppressed by the aforementioned olefinically unsaturated compound (B-2), and the formability of a high dot at a low exposure is improved.

[0137] The aforementioned ethylenically unsaturated compound (B-2) having the structure represented by formula (4) exerts an oxygen inhibition suppressing effect through the following reaction mechanism. That is, the hydrogen atom bonded to the carbon atom in the α position of the vinyl group of the aforementioned ethylenically unsaturated compound (B-2) is abstracted by a peroxide radical generated from oxygen in the air, forming an allyl radical intermediate. The reactivity of the vinyl group of this allyl radical intermediate is high, promoting the curing reaction, and thus, the influence of oxygen inhibition by the peroxide radical generated from oxygen in the air can be offset. Therefore, by including the aforementioned ethylenically unsaturated compound (B-2) in the photosensitive resin composition layer (b) constituting the flexible printing original plate of the present embodiment, there is a tendency for the formation of a poor dot due to oxygen inhibition to be suppressed, and the formability of a high light dot when exposure is performed at a low light intensity to be improved.

[0138] As such an ethylenically unsaturated compound (B-2), diphenyl acid diallyl ester, diprenyl glycerin ether, and the like can be cited.

[0139] Among these, from the viewpoint of the formability of a dot when exposure is performed at a low light intensity for the flexible printing original plate of the present embodiment, as the ethylenically unsaturated compound (B-2), diprenyl glycerin ether represented by the following formula (5) is preferable.

[0140]

[0141] From the viewpoint of the formability of a dot when exposure is performed at a low light intensity for the flexible printing original plate of the present embodiment, when the total amount of the photosensitive resin composition layer (b) is taken as 100 mass%, the content of the aforementioned ethylenically unsaturated compound (B-2) is preferably 0.1 mass% or more and 5 mass% or less, more preferably 1 mass% or more and 3 mass% or less, and further preferably 1.5 mass% or more and 3 mass% or less.

[0142] In addition, as the ethylenically unsaturated compound (b-2) other than the ethylenically unsaturated compound (B-2), it is not limited to the following substances, and olefins such as ethylene, propylene, 4-vinyltoluene, styrene, 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene; acetylenes; (meth)acrylic acid and / or derivatives thereof; halogenated olefins; unsaturated nitriles such as acrylonitrile; unsaturated amides such as acrylamide, methacrylamide, and derivatives thereof; unsaturated dicarboxylic acids such as maleic anhydride, maleic acid, fumaric acid, and derivatives thereof; vinyl acetates; N-vinylpyrrolidone; N-vinylcarbazole; N-substituted maleimide compounds, and the like can be cited.

[0143] Among them, from the viewpoint of ultraviolet curability, print resistance of the cured photosensitive resin composition layer (b), as the ethylenically unsaturated compound (b-2), it is preferable to contain (meth)acrylic acid and / or its derivatives.

[0144] As the aforementioned derivatives, not limited to the following substances, can be exemplified, for example, alicyclic compounds having a cycloalkyl group, a bicycloalkyl group, a cycloalkenyl group, a bicycloalkenyl group, etc.; aromatic compounds having a benzyl group, a phenyl group, a phenoxy group, or a naphthalene skeleton, an anthracene skeleton, a biphenyl skeleton, a phenanthrene skeleton, a fluorene skeleton, etc.; compounds having an alkyl group, a halogenated alkyl group, an alkoxyalkyl group, a hydroxyalkyl group, an aminoalkyl group, a glycidyl group, etc.; ester compounds formed with an alkylene glycol, a polyoxyalkylene glycol, a polyalkylene glycol, a polyol such as trimethylolpropane, etc.; compounds having a polysiloxane structure such as a polydimethylsiloxane, a polydiethylsiloxane, etc.

[0145] In addition, the ethylenically unsaturated compound (b-2) can be a heteroaromatic compound containing an element such as nitrogen, sulfur, etc.

[0146] As the aforementioned (meth)acrylic acid and / or its derivatives, not limited to the following substances, can be exemplified, for example, diacrylate esters and dimethacrylate esters of alkane diols such as 1,6-hexanediol, 1,9-nonanediol, etc.; diacrylate esters and dimethacrylate esters of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butanediol; trimethylolpropane tri(meth)acrylate; dimethyloltricyclodecane di(meth)acrylate; isobornyl (meth)acrylate; phenoxy polyethylene glycol (meth)acrylate; pentaerythritol tetra(meth)acrylate, etc.

[0147] They can be used only singly in 1 kind, or in combination in 2 or more kinds.

[0148] From the viewpoint of mechanical strength of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment, as the ethylenically unsaturated compound (b-2), it is preferable to use at least 1 or more kinds of (meth)acrylate esters, and more preferable to use at least 1 or more kinds of difunctional (meth)acrylate esters.

[0149] From the viewpoint of improving the non-volatility of the ethylenically unsaturated compound (b-2) of the flexographic printing precursor of the present embodiment at the time of production and / or storage, the number average molecular weight (Mn) of the ethylenically unsaturated compound (b-2) is preferably 100 or more, and from the viewpoint of compatibility with other components, preferably less than 1000, and more preferably 200 or more and 800 or less.

[0150] From the viewpoint of the print durability of the flexographic printing plate obtained using the flexographic printing master of the present embodiment, the content of the ethylenically unsaturated compound (b-2) in the photosensitive resin composition layer (b) is preferably 2% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 25% by mass or less, and further preferably 2% by mass or more and 20% by mass or less, when the total amount of the photosensitive resin composition layer (b) is 100% by mass.

[0151] <Photopolymerization initiator (b-3)>

[0152] The photosensitive resin composition layer (b) preferably contains a photopolymerization initiator (b-3). The photopolymerization initiator (b-3) refers to a compound that generates a radical by absorbing light energy, and examples include a cleavage-type photopolymerization initiator, a hydrogen abstraction-type photopolymerization initiator, a compound having a site that functions as a hydrogen abstraction-type photopolymerization initiator and a site that functions as a cleavage-type photopolymerization initiator in the same molecule, and the like.

[0153] As such a photopolymerization initiator (b-3), not limited to the following substances, but examples include, for example, benzophenone, 4,4-bis(diethylamino)benzophenone, 3,3',4,4'-benzophenonetetracarboxylic anhydride, 3,3',4,4'-tetramethoxybenzophenone, and the like benzophenone-based compounds; 2-tert-butylanthraquinone, 2-ethylanthraquinone, and the like anthraquinone-based compounds; 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, and the like thioxanthone-based compounds; Michler's ketone; 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, trichloroacetophenone, and the like acetophenone-based compounds; benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and the like benzoin ether-based compounds; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and the like acylphosphine oxide-based compounds; methyl benzoylformate; 1,7-bisazinylheptane; 9-phenylacridine; azo compounds such as azobisisobutyronitrile, diazo compounds, tetrazene compounds, and the like.

[0154] They can be used alone only 1 kind, or 2 or more kinds in combination.

[0155] Among them, from the viewpoint of the hardness of the flexographic printing plate produced using the flexographic printing plate precursor of the present embodiment, as the photopolymerization initiator (b-3), a compound having a carbonyl group is preferable, and an aromatic carbonyl compound such as a benzophenone-based compound, a thioxanthone-based compound, and the like is more preferable.

[0156] If the content of the photopolymerization initiator (b-3) in the photosensitive resin composition layer (b) is reduced, the overformation of the intermediate style dot at the time of plate making by high-intensity exposure of the flexographic printing plate precursor of the present embodiment can be suppressed. On the other hand, if the content of the photopolymerization initiator (b-3) is increased, the formability of the flexographic printing plate rises, and thus, the dot formation failure at the time of plate making by low-intensity exposure can be suppressed. From the viewpoint of taking into account the dot formability at both low and high intensities, when the total amount of the photosensitive resin composition layer (b) is set to 100.0% by mass, the content of the photopolymerization initiator (b-3) in the photosensitive resin composition layer (b) is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 0.5% by mass or more and 5.0% by mass or less, and further preferably 1.0% by mass or more and 5.0% by mass or less.

[0157] <liquid diene (b-4)>

[0158] The photosensitive resin composition layer (b) preferably contains a liquid diene.

[0159] The liquid diene refers to a compound having a carbon-carbon double bond in a liquid state.

[0160] Herein, the "liquid state" of the "liquid diene" in the present specification refers to a property of being able to easily flow and deform and being solidified into a deformed shape by cooling. The liquid diene is a term corresponding to an elastomer having a property of instantaneously deforming according to an external force when the external force is applied, and recovering the original shape in a short time when the external force is removed.

[0161] The liquid diene can be distinguished from the aforementioned thermoplastic elastomer (b-1) from the point that it flows and deforms even at ordinary temperature, and from the olefinically unsaturated compound (b-2) from the point that it is a copolymer having 50% by mass or more of a diene component.

[0162] As the liquid diene (b-4), not limited to the following substances, for example, a liquid polybutadiene, a liquid polyisoprene, a modified product of a liquid polybutadiene, a modified product of a liquid polyisoprene, a liquid acrylonitrile-butadiene copolymer, a liquid styrene-butadiene copolymer can be listed.

[0163] The liquid diene is a copolymer having 50% by mass or more of a diene component.

[0164] Among them, from the viewpoint of the mechanical properties of the flexible printing original plate of the present embodiment and the flexible printing plate manufactured using the same, as the liquid diene, liquid polybutadiene is preferable.

[0165] Further, from the viewpoint of making the hardness of the flexible printing original plate of the present embodiment and the flexible printing plate manufactured using the same appropriate, the 1,2-vinyl bond amount of the liquid diene, preferably the liquid polybutadiene, is preferably 1% or more and 80% or less, more preferably 5% or more and 70% or less, further preferably 5% or more and 65% or less.

[0166] Here, the "1,2-vinyl bond amount" refers to the proportion of the 1,2-linkage among the conjugated diene monomers incorporated in the 1,2-linkage, 3,4-linkage, and 1,4-linkage bonding modes. The 1,2-vinyl bond amount can be calculated from the peak ratio of the H-NMR (magnetic resonance spectrum). 1 The peak ratio of the H-NMR (magnetic resonance spectrum) is calculated.

[0167] Note that the 1,2-polybutadiene, which is the liquid polybutadiene having a 1,2-vinyl bond, has a high reactivity in radical polymerization because the vinyl group as a double bond becomes a side chain, and is preferable from the viewpoint of improving the hardness of the photosensitive resin composition layer (b).

[0168] Further, the liquid polybutadiene is generally a mixture of 1,2-polybutadiene having a 1,2-vinyl bond and 1,4-polybutadiene having a 1,4-vinyl bond, but from the viewpoint of improving the softness of the flexible printing original plate of the present embodiment and the flexible printing plate manufactured using the same, it is preferable to contain 1,4-polybutadiene in the liquid diene. The 1,4-polybutadiene exists as cis-type 1,4-polybutadiene and trans-type 1,4-polybutadiene. With regard to the 1,4-polybutadiene, both the cis-type and the trans-type have a vinyl group as a double bond inside, and thus have a low reactivity in radical polymerization, and finally a soft resin can be manufactured.

[0169] When a plurality of liquid polybutadienes having different 1,2-vinyl bond amounts are used in mixture, the average value thereof is set as the aforementioned 1,2-vinyl bond amount.

[0170] From the viewpoint of being able to easily adjust the reactivity of the photosensitive resin composition layer (b), it is preferable to mix liquid polybutadiene having a 1,2-vinyl bond amount of 10% or less with liquid polybutadiene having a 1,2-vinyl bond amount of 80% or more, and adjust the overall 1,2-vinyl bond amount. It is more preferable to mix liquid polybutadiene having a 1,2-vinyl bond amount of 5% or less with liquid polybutadiene having a 1,2-vinyl bond amount of 80% or more, and adjust the overall 1,2-vinyl bond amount.

[0171] Further, regarding the number average molecular weight of the liquid diene (b-4), there is no particular limitation as long as it is liquid at 20°C, and from the viewpoint of the print durability and handling properties of the flexographic printing plate produced using the flexographic printing precursor of the present embodiment, it is preferably 500 or greater and 60,000 or less, more preferably 500 or greater and 50,000 or less, and further preferably 800 or greater and 50,000 or less.

[0172] From the viewpoint of the print durability of the flexographic printing precursor of the present embodiment and the flexographic printing plate produced using the same, when the total amount of the photosensitive resin composition layer (b) is taken as 100% by mass, the content of the liquid diene (b-4) in the photosensitive resin composition layer (b) is preferably 10% by mass or greater and 40% by mass or less, more preferably 15% by mass or greater and 40% by mass or less, and further preferably 20% by mass or greater and 40% by mass or less.

[0173] <Stabilizer (b-5)>

[0174] The photosensitive resin composition layer of the flexographic printing precursor of the present embodiment preferably contains a stabilizer (b-5).

[0175] The stabilizer (b-5) refers to a component contained in the photosensitive resin composition layer (b) for the purpose of preventing the deterioration or gelation of a heat polymerization inhibitor, an antioxidant, or the like during the production or storage of the flexographic printing precursor.

[0176] Regarding the flexographic printing precursor of the present embodiment, from the viewpoint of balancing the formation of a high dot portion at the time of low-intensity exposure and the suppression of the over-formation of an intermediate style dot at the time of high-intensity exposure, in the photosensitive resin composition layer (b), the heat release amount at the time of the exothermic peak of the photo DSC is determined to be a prescribed numerical range.

[0177] As part or all of the stabilizer (b-5), at least one compound represented by the following formula (2) or (3) (hereinafter referred to as a stabilizer (B-5)) is contained, and thus there is a tendency that the time to the exothermic peak and the heat release amount at the peak top of the photosensitive resin composition layer (b) can be controlled.

[0178] In the photosensitive resin composition layer (b) of the flexographic printing precursor of the present embodiment, from the viewpoint of balancing the stability at the time of production and storage and the dot formation at the time of low-intensity exposure and high-intensity exposure, as the stabilizer (b-5), at least one stabilizer (B-5) is preferably contained.

[0179] Note that the compound represented by the following formula (2) or (3) (stabilizer (B-5)) can be all or part of the aforementioned stabilizer (b-5).

[0180]

[0181]

[0182] In formula (2) and (3), R3, R5 each independently represents an alkyl group having 1 to 4 carbon atoms. R4, R6 each independently represents an alkyl group having 1 to 12 carbon atoms.

[0183] If the content of the stabilizer (b-5) in the photosensitive resin composition layer (b) is increased, the manufacturing stability of the flexographic printing plate is improved. On the other hand, the stabilizer (b-5) mostly consumes a reactive radical in the curing reaction at the time of exposure, and thus, the formability of the flexographic printing plate is reduced.

[0184] By including at least one of the aforementioned stabilizer (B-5) as a part or all of the stabilizer (b-5) in the photosensitive resin composition layer (b), there is a tendency to ensure the stability of the flexographic printing plate precursor of the present embodiment at the time of manufacturing and storage, and to improve the formability of the flexographic printing plate at the time of low-intensity exposure.

[0185] The aforementioned stabilizer (B-5) has a phenol structure and a sulfur atom in one molecule, and exerts a high efficient stabilizing effect by the synergistic effect of the phenol-based antioxidant and the sulfur-based antioxidant. In addition, since an alkyl group is included in the molecule, the dispersibility in the photosensitive resin composition layer (b) is excellent, and thus, a high efficient stabilizing effect can be exerted compared to other sulfur-based stabilizers. Furthermore, the sulfur-based antioxidant decomposes peroxide, and thus, the generation of peroxide radicals, which are one of the reaction species that cause oxygen inhibition at the time of low-intensity exposure, can be prevented. In addition, the sulfur atom and the alkyl group in the molecule have a covalent bond, and thus, the electron donating property of the sulfur is improved, and peroxide radicals are easily decomposed, and thus, the effect of inhibiting oxygen inhibition at the time of low-intensity exposure is high, and the dot formability can be further improved.

[0186] Based on these properties, by including at least one of the aforementioned stabilizer (B-5) in the photosensitive resin composition layer (b) of the flexographic printing plate precursor of the present embodiment, the influence of oxygen inhibition at the time of low-intensity exposure can be reduced, and the formability of the flexographic printing plate can be improved.

[0187] From the viewpoint of the dot formability of the flexographic printing plate obtained by using the flexographic printing plate precursor of the present embodiment at the time of low-intensity exposure, when the total amount of the photosensitive resin composition layer (b) is 100% by mass, the content of the aforementioned stabilizer (B-5) is preferably 0.45% by mass or less, more preferably 0.10% by mass or more and 0.45% by mass or less, and further preferably 0.30% by mass or more and 0.40% by mass or less.

[0188] Further, from the same viewpoint, the ratio of the aforementioned stabilizer (B-5) in the total amount of 100 mass% of the stabilizer (b-5) contained in the photosensitive resin composition layer (b) is preferably 60 mass% or more and 100 mass% or less, more preferably 80 mass% or more and 100 mass% or less, and further preferably 90 mass% or more and 100 mass% or less.

[0189] Further, from the viewpoint of taking into account the dot formability at the time of low-intensity exposure and the dot formability at the time of high-intensity exposure, the ratio of the amount of the aforementioned stabilizer (B-5) contained in the photosensitive resin composition layer (b) is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and further preferably 10 parts by mass or more and 15 parts by mass or less, when the amount of the photopolymerization initiator (b-3) contained in the photosensitive resin composition layer (b) is 100 parts by mass.

[0190] As the stabilizer (b-5) other than the aforementioned stabilizer (B-5), a stabilizer generally used in the field of resin materials or rubber materials can be used. Specifically, a phenol-based material can be exemplified.

[0191] As such a phenol-based material, not limited to the following materials, for example, vitamin E, tetra- (methylene-3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate) methane, 2, 5-di-tert-butylhydroquinone, 2, 6-di-tert-butyl-p-cresol, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and the like can be exemplified.

[0192] The stabilizer (b-5) such as a heat polymerization inhibitor and an antioxidant can be used alone only one kind, or two or more kinds in combination.

[0193] <Dye (b-6)>

[0194] The flexible printing original of the present embodiment preferably contains a dye (b-6) in the photosensitive resin composition layer (b).

[0195] The dye (b-6) refers to a component contained in the photosensitive resin composition layer (b) as a coloring means for improving the recognition.

[0196] Regarding the flexible printing original of the present embodiment, from the viewpoint of taking into account the formability of the high light dot portion at the time of low-intensity exposure and the suppression of the excessive formation of the intermediate style dot at the time of high-intensity exposure, in the photosensitive resin composition layer (b), the amount of heat release at the time of exothermic peak of the photo DSC is determined to be a prescribed numerical range.

[0197] As a part or all of the dye (b-6), a dye having a 1,4-diamino-5,8-dihydroxyanthraquinone skeleton in the molecular structure (hereinafter referred to as dye (B-6)) is contained, whereby there is a tendency to control the exothermic behavior of the photosensitive resin composition layer (b).

[0198] It is known that 1,4-diamino-5,8-dihydroxyanthraquinone forms hydrogen bonds between the carbonyl oxygen atom and the amino hydrogen atom and between the carbonyl oxygen atom and the hydroxyl hydrogen atom, respectively, and that, as a result of this interaction, it also interacts with each of the components (ethylenic monomer, photopolymerization initiator, stabilizer, etc.) in the photosensitive resin composition (b). The aforementioned dye (B-6) having a 1,4-diamino-5,8-dihydroxyanthraquinone skeleton in the molecular structure has the effect of moderating the reactivity of the photopolymerization initiator in the photosensitive resin composition layer (b) by virtue of this interaction, and thus, it is possible to suppress the generation of radicals. Furthermore, it has absorbance with respect to UV, and thus, in particular when exposure is performed using a high-illuminance exposure machine, there is a tendency to exert a good effect and to suppress the excessive formation of intermediate style dots.

[0199] In addition, from the viewpoint of improving dispersion within the photosensitive resin composition layer (b) and effectively exerting an effect, the aforementioned dye (B-6) having a 1,4-diamino-5,8-dihydroxyanthraquinone skeleton is more preferably a dye having a molecular structure represented by the following formula (1) (hereinafter referred to as dye (B-6')).

[0200]

[0201] In formula (1), R1, R2 each independently represents an alkyl group having 1 to 4 carbon atoms.

[0202] From the viewpoint of controlling the exothermic behavior of the photo-DSC, the content of the aforementioned dye (B-6') in the photosensitive resin composition layer (b) is preferably 0.005 mass% or more and 0.1 mass% or less, more preferably 0.009 mass% or more and 0.05 mass% or less, and further preferably 0.009 mass% or more and 0.03 mass% or less.

[0203] As the dye (b-6) other than the aforementioned dye (B-6), dyes other than the following dyes can be exemplified, such as basic dyes, acid dyes, direct dyes, etc. that exhibit water solubility; sulfur dyes, oil-soluble dyes, disperse dyes, etc. that exhibit non-water solubility. The aforementioned dye (b-6) can contain, in addition to anthraquinone-based dyes, indigo-based dyes, azo-based dyes, azo-based oil-soluble dyes, etc.

[0204] <auxiliary additive ingredients>

[0205] As the auxiliary additive ingredient, not limited to the following substances, for example, a polymer containing a polar group, other plasticizer than the liquid diene, an ultraviolet absorber, a pigment, and the like can be exemplified.

[0206] As the auxiliary additive ingredient, not limited to the following substances, for example, a polymer containing a polar group, other plasticizer than the liquid diene, an ultraviolet absorber, a pigment, and the like can be exemplified.

[0207] As the polymer containing a polar group, not limited to the following substances, for example, a water-soluble or water-dispersible copolymer having a polar group such as a carboxyl group, an amino group, a hydroxyl group, a phosphoric acid group, a sulfonic acid group, a salt thereof, and the like can be exemplified. More specifically, for example, a carboxyl group-containing acrylonitrile-butadiene rubber, a carboxyl group-containing styrene-butadiene rubber, a carboxyl group-containing polymer of an aliphatic conjugated diene, an emulsion polymer of an ethylenically unsaturated compound having a phosphoric acid group or a carboxyl group, a sulfonic acid group-containing polyurethane, a carboxyl group-containing butadiene latex, and the like can be exemplified. These polymers containing a polar group can be used alone only one kind, or two or more kinds in combination.

[0208] Among these, from the viewpoint of obtaining a high resolution from a flexographic printing plate obtained using the flexographic printing plate precursor of the present embodiment, as the polymer containing a polar group, a butadiene latex containing a carboxyl group is preferable.

[0209] As the other plasticizer than the liquid diene, not limited to the following substances, for example, a hydrocarbon oil such as a naphthene oil, a paraffin oil, and the like; a conjugated diene rubber having a liquid diene as a main component such as a liquid acrylonitrile-butadiene copolymer, a liquid styrene-butadiene copolymer, and the like; an ester-based plasticizer such as a polystyrene having a number average molecular weight of 2000 or less, a sebacate, a phthalate, and the like can be exemplified.

[0210] The other plasticizer than the liquid diene described above can have a hydroxyl group, a carboxyl group. In addition, the other plasticizer described above can be imparted with a photopolymerizable reactive group such as a (meth)acryloyl group.

[0211] The other plasticizer described above can be used alone only one kind, or two or more kinds in combination.

[0212] As the ultraviolet absorber, not limited to the following substances, for example, a well-known benzophenone-based compound, a salicylate-based compound, an acrylonitrile-based compound, a metal complex salt-based compound, a hindered amine-based compound can be exemplified.

[0213] In addition, a dye / pigment shown below can be used as the ultraviolet absorber.

[0214] As such an ultraviolet absorber, without being limited to the following substances, for example, 2-ethoxy-2'-ethyl oxanilide, 2,2'-dihydroxy-4-methoxybenzophenone, and the like can be exemplified.

[0215] A pigment is effective as a coloring means for improving recognizability.

[0216] As a pigment, without being limited to the following substances, for example, natural pigments, synthetic inorganic pigments, synthetic organic pigments, and the like can be exemplified.

[0217] As a synthetic organic pigment, azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, phthalocyanine pigments can be exemplified.

[0218] When the total amount of the photosensitive resin composition layer (b) is set to 100 mass%, the total amount of the above-mentioned auxiliary additive component is preferably 0 mass% or more and 10 mass% or less, more preferably 0 mass% or more and 5 mass% or less, and further preferably 0 mass% or more and 3 mass% or less.

[0219] (Infrared ablation layer (c))

[0220] With respect to the flexible printing master plate of the present embodiment, an infrared ablation layer (c) containing an infrared-sensitive substance is laminated on the photosensitive resin composition layer (b).

[0221] The infrared ablation layer (c) preferably contains a binder polymer, an infrared-sensitive substance, and a non-infrared radiation shielding substance.

[0222] As a binder polymer, without being limited to the following substances, for example, polyamides, polyesters, and copolymers formed from monovinyl-substituted aromatic hydrocarbons and conjugated dienes, and the like can be exemplified. Among them, copolymers formed from monovinyl-substituted aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, and conjugated dienes such as 1,3-butadiene and isoprene are preferable.

[0223] When the aforementioned binder polymer is used to constitute the infrared ablation layer (c), there is a tendency that the affinity with the photosensitive resin composition is high and the adhesion is good.

[0224] As an infrared-sensitive substance, for example, a monomer or a compound that generally has a strong absorption in the range of 750 to 2000 nm is suitably used.

[0225] As an infrared-sensitive substance, specifically, inorganic pigments such as carbon black, graphite, copper chromite, and chromium oxide; pigments such as polyphthalocyanine compounds, cyanine pigments, and metal thiolate pigments; and the like can be exemplified.

[0226] These infrared ray sensitive substances are added to the infrared ablation layer (c) in a range that imparts a sensitivity that enables ablation using the laser light used. In general, an addition amount of 10 to 80 mass% is preferred.

[0227] As the shielding substance other than infrared radiation, a substance that reflects or absorbs radiation such as ultraviolet rays can be used. Radiation absorbers of radiation such as ultraviolet rays, carbon black, graphite, and the like are suitable examples, and the addition amount is set in a manner that enables the desired optical density to be achieved. In general, addition is preferably performed in a manner that the optical density becomes 2 or more, preferably 3 or more.

[0228] [Manufacturing method of flexographic printing plate]

[0229] The manufacturing method of the flexographic printing plate of the present embodiment, using the flexographic printing precursor of the present embodiment, has the following steps: first, a first step in which ultraviolet rays are irradiated from the support (a) side; a second step in which a negative pattern is produced by laser ablation of the infrared ablation layer (c) provided on the photosensitive resin composition layer (b) by irradiation of infrared rays; a third step in which the photosensitive resin composition layer (b) is subjected to pattern exposure by irradiation of ultraviolet rays using the aforementioned infrared ablation layer (c) on which the aforementioned pattern has been drawn as a mask; and a fourth step in which the unexposed portion of the aforementioned photosensitive resin composition layer (b) is removed.

[0230] Thereafter, a step of performing post-exposure processing as needed is performed, and a flexographic printing plate (relief printing plate) based on the cured product of the photosensitive resin composition layer (b) is obtained.

[0231] Note that, from the viewpoint of imparting releasability of the flexographic printing plate in the printing step from ink, the surface of the aforementioned flexographic printing plate can be brought into contact with a liquid containing a silicone compound and / or a fluorine compound.

[0232] Figure 2 A schematic diagram showing the manufacturing method of a flexographic printing plate using the flexographic printing precursor of the present embodiment is shown in FIG. 1. Hereinafter, each step is described in detail.

[0233] (First step: S1)

[0234] In the first step, the method of irradiating ultraviolet rays from the support (a) side to the photosensitive resin composition layer (b) is not particularly limited, and a publicly known irradiation unit can be used. The wavelength of the ultraviolet rays irradiated at this time is preferably 150 to 500 nm, more preferably 300 to 400 nm.

[0235] As the light source of the ultraviolet rays, light sources other than the following can be used, and for example, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a xenon lamp, a zircon lamp, a carbon arc lamp, an ultraviolet fluorescent lamp, and the like can be used.

[0236] Note that the first process can be performed before the second process described later, or can be performed after the second process.

[0237] (Second process: S2)

[0238] In the second process, the method of irradiating the infrared ablation layer (c) with infrared rays to draw a processing pattern is not particularly limited, and a publicly known irradiation unit can be used. Note that the irradiation of the infrared ablation layer (c) with infrared rays can be performed from the side of the infrared ablation layer (c).

[0239] The flexible printing original plate of the present embodiment has a cover film, and before the irradiation of infrared rays, the cover film is first peeled off. Thereafter, the infrared ablation layer (c) pattern is irradiated with infrared rays, and the resin of the infrared ray irradiation portion is decomposed to draw and process a pattern. Thus, a mask (c') of the infrared ablation layer (c) can be formed on the photosensitive resin composition layer (b).

[0240] In the second process, as a suitable infrared laser, for example, an ND / YAG laser (for example, 1064 nm) or a diode laser (for example, 830 nm) can be exemplified. A laser system suitable for CTP plate making technology is commercially available, and for example, a diode laser system CDI Spark (ESKO GRAPHICS Co.) can be used. The laser system includes a rotating cylinder that holds the flexible printing original plate of the present embodiment, an irradiation device of an IR laser, and a design computer, and image information is directly delivered from the design computer to the laser device.

[0241] (Third process: S3)

[0242] In the third process, the photosensitive resin composition layer (b) is irradiated with ultraviolet rays using the infrared ablation layer (c) on which a pattern is drawn and processed as a mask to perform pattern exposure, and a printing pattern (b') is formed. At this time, the light that has passed through the mask promotes the curing reaction of the photosensitive resin composition layer (b), and the concave-convex of the pattern of the infrared ablation layer (c) is reversed and transferred to the photosensitive resin composition layer (b). As for the irradiation of ultraviolet rays, the entire surface of the flexible printing original plate of the present embodiment can be irradiated.

[0243] The third process can be performed in a state where the flexible printing original plate of the present embodiment is mounted to a laser cylinder, and generally, the flexible printing original plate of the present embodiment is removed from the laser device, and an irradiation unit that is conventionally used is used for the irradiation. The irradiation unit can use the same unit as exemplified in the ultraviolet irradiation in the first process.

[0244] (Fourth process: S4)

[0245] The fourth step is a step of removing the unexposed portions of the infrared ablation layer (c) and the photosensitive resin composition layer (b).

[0246] The removal method in the fourth step (developing step) is not particularly limited, and a publicly known method can be applied.

[0247] Specifically, as described above, the photosensitive resin composition layer (b) of the flexible printing original plate of the present embodiment is exposed to form a printing pattern (b'), and thereafter, the unexposed portions are washed away with a solvent developing solvent or a water developing cleaning solution, and the unexposed portions can be removed. In addition, by, for example, heating the unexposed portions to 40°C to 200°C and bringing them into contact with a prescribed absorption layer capable of absorbing the aforementioned heated unexposed portions, that is, by performing heat development, the unexposed portions can also be removed.

[0248] Thereafter, a post-exposure treatment is performed as necessary, and thus a flexible printing plate is manufactured.

[0249] Note that when an intermediate layer (d) is provided between the infrared ablation layer (c) and the photosensitive resin composition layer (b), it can be removed at the same time in the developing step.

[0250] As the developing solvent for solvent developing the unexposed portions, there is no particular limitation, and esters such as heptyl acetate, 3-methoxybutyl acetate, and the like; hydrocarbons such as petroleum distillates, toluene, decalin, and the like; and substances in which alcohols such as 1-propanol, 2-propanol, 1-butanol, 1-pentanol, and the like are mixed in chloro-based organic solvents such as tetrachloroethylene can be exemplified. The cleaning of the unexposed portions is performed by spraying from a nozzle or brushing based on a brush.

[0251] In addition, as the water developing cleaning solution, water, an alkaline aqueous solution, a neutral detergent, a surfactant can be suitably used.

[0252] The surfactant can be exemplified by anionic surfactants, amphoteric surfactants, nonionic surfactants, and the like. They can be used alone only one kind, or two or more kinds can be used in mixture.

[0253] As the anionic surfactant, there is no particular limitation, and sulfates, higher alcohol sulfates, higher alkyl ether sulfates, sulfated olefins, alkylbenzenesulfonates, a-olefin sulfonates, phosphate esters, dithiophosphate esters, and the like can be exemplified.

[0254] As the amphoteric surfactant, there is no particular limitation, and amino acid-type amphoteric surfactants, betaine-type amphoteric surfactants, and the like can be exemplified.

[0255] As the nonionic surfactant, without being limited to the following substances, for example, polyethylene glycol type surfactants such as higher alcohol ethylene oxide adduct, alkyl phenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkyl amine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, and the like; polyhydric alcohol type surfactants such as glycerin fatty acid ester, pentaerythritol fatty acid ester, fatty acid ester of sorbitol and anhydrosorbitol, alkyl ester of polyhydric alcohol, fatty acid amide of alkanol amine, and the like can be listed.

[0256] In addition, the basic aqueous solution can contain a pH adjuster. As the pH adjuster, any of an organic material and an inorganic material can be used, and it is preferable that the pH adjuster be capable of adjusting the pH to 9 or more. As the pH adjuster, without being limited to the following substances, for example, sodium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, sodium succinate, and the like can be listed.

[0257] As the absorption layer of the heat development, without being particularly limited, for example, nonwoven fabric materials, paper materials, fiber fabrics, continuous bubble foams, and porous materials can be listed. Among them, nonwoven fabric materials formed of nylon, polyester, polypropylene, and polyethylene, and combinations of these nonwoven fabric materials are preferable, and nonwoven continuous fiber webs of nylon or polyester are more preferable.

[0258] Examples

[0259] Hereinafter, specific examples and comparative examples will be listed, and the present embodiment will be described in more detail, but the present application is not at all limited to the following examples and comparative examples.

[0260] Regarding the examples and comparative examples described later, the following measurement methods of physical properties are shown.

[0261] 〔Time from the start of irradiation based on light DSC to the exothermic peak and exothermic amount at the peak top〕

[0262] The measurement value of the light DSC is obtained using the following measurement method.

[0263] The DSC measurement device uses DSC-7000X manufactured by Hitachi Hightech Co., Ltd., and a light DSC measurement unit is attached thereto to be set in a manner that enables DSC measurement while irradiating light.

[0264] The light source for light irradiation uses LA-410UV manufactured by HAYASHI REPIC Co., Ltd., so that it can extract light of a wavelength of 365 nm using a band pass filter and irradiate the sample.

[0265] The measurement is performed under air circulation at a rate of 50 mL / minute.

[0266] A 0.5 mm thick photosensitive resin composition sample obtained in the following <Production of a sample for light DSC measurement> was punched into a 7 mm diameter circle, and about 18 mg of the obtained photosensitive resin composition sample was set in a dedicated aluminum pan, and a wavelength 365 nm light was irradiated at an irradiation intensity of 10 mW / cm 2 The exothermic behavior was measured under conditions of 10 minutes from the start of irradiation, a temperature of 25°C, and a data acquisition interval of 0.1 seconds.

[0267] At this time, the horizontal axis was set as time (seconds), and the exothermic amount was plotted with the vertical axis in μW, and the time taken from the start of irradiation to the peak, and the value obtained by dividing the exothermic amount at the peak by the mass (unit: μW / mg) were calculated.

[0268] The measurement results are shown in Tables 1 to 3.

[0269] [Manufacturing Example]

[0270] (Production of a laminate for infrared ablation layer formation)

[0271] Carbon black (CB) as an infrared absorber, 100 parts by mass, Solsperse 39000 (manufactured by Japan Lubrizol Corporation, trade name, base number 30 mgKOH / g) as a dispersant, 20 parts by mass, TUFTEC H1051 (manufactured by Asahi Kasei Corporation, trade name) as a binder polymer, a hydrogenated product of a styrene-butadiene-styrene copolymer elastomer, 80 parts by mass, and toluene, 600 parts by mass were mixed to obtain an infrared ablation layer coating liquid.

[0272] The infrared ablation layer coating liquid was applied to a 100 μm thick PET film to be a cover film in such a manner that the film thickness after drying became 3 μm, and a drying treatment was performed at 90°C for 2 minutes to obtain a laminate of an infrared ablation layer and a cover film, that is, a laminate for infrared ablation layer formation.

[0273] (Production of a support)

[0274] As a solution for an adhesive layer to be coated on a support, a styrene-1,3-butadiene block copolymer, Tufprene 912 (manufactured by Asahi Kasei Corporation, trade name), 55 parts by mass, a paraffin oil (average number of carbon atoms: 33, average molecular weight: 470, density at 15°C: 0.868), 38 parts by mass, 1,9-nonanediol diacrylate, 2.5 parts by mass, 2,2-dimethoxyphenyl phenyl ethanone, 1.5 parts by mass, an epoxy ester 3000M (manufactured by Kyoeisha Chemical Co., Ltd., trade name), 3 parts by mass, and VALIFAST YELLOW 3150 (manufactured by ORIENT CHEMICAL INDUSTRIES Co., Ltd., trade name), 1.5 parts by mass, were mixed in a ratio of 55:38:2.5:1.5:3:1.5, and dissolved in toluene to obtain a solution having a solid content of 25%.

[0275] Subsequently, using a doctor blade coater, the solution was coated on one side of a polyester film having a thickness of 100 μm so that the UV transmittance became 10%, and dried at 80°C for 1 minute to obtain a support having an adhesive layer.

[0276] The UV transmittance of the support was calculated as follows: using an ultraviolet exposure machine, AFP-1500 (manufactured by Asahi Kasei Corporation, trade name), the transmittance intensity was measured using a UV illuminometer, MO-2 type machine (manufactured by ORC, trade name, UV-35 Filter), and the UV transmittance was calculated.

[0277] (Production of photosensitive resin composition)

[0278] <Production of photosensitive resin composition 1>

[0279] A photosensitive resin composition 1 (described as Resin 1 in Table 1) was produced by mixing, using a pressurized kneader, a styrene-butadiene-styrene copolymer [D-KX405: manufactured by Clayton Corporation], 67.5 parts by mass, a liquid polybutadiene [LBR-352: manufactured by Kobelco Chemicals, Ltd.], 21.5 parts by mass, 1,9-nonanediol diacrylate, 9.0 parts by mass, 1,6-hexanediol dimethacrylate, 2.0 parts by mass, di-tert-pentenyl glyceryl ether [DPNG: manufactured by Kobelco Chemicals, Ltd.], 2.2 parts by mass, a photopolymerization initiator [2,2-dimethoxy-2-phenylphenyl ethanone: manufactured by BASF Corporation], 4.0 parts by mass, 2,4-bis[(octylthio)methyl]o-cresol [Irganox 1520L: manufactured by BASF Corporation] as a stabilizer, 0.4 parts by mass, and 1,4-bis[(4-tert-butylphenyl)amino]-5,8-dihydroxy-9,10-anthraquinone [C.I. Solvent Green 28: manufactured by Nippon Kayaku Co., Ltd.] as a dye, 0.01 parts by mass.

[0280] <Production of photosensitive resin compositions 2 to 28>

[0281] The composition was changed as in Tables 1 to 3 below, and otherwise, the same operation as in the photosensitive resin composition 1 was performed to obtain photosensitive resin compositions 2 to 28 (expressed as resins 2 to 28 in Tables 1 to 3).

[0282] Each material in Tables 1 to 3 is shown below.

[0283] LIR-305: manufactured by Zeon Corporation, liquid polybutadiene

[0284] Liquid polybutadiene A: liquid polybutadiene having a number average molecular weight of 3200, a weight average molecular weight / number average molecular weight = 1.29, a 1,2-vinyl bond content of 90%, and a viscosity at 45°C of 25.0 Pa-s

[0285] Liquid polybutadiene B: liquid polybutadiene having a number average molecular weight of 4600, a weight average molecular weight / number average molecular weight = 3.79, a 1,2-vinyl bond content of 1%, and a viscosity at 40°C of 0.70 Pa-s

[0286] DAD: manufactured by Nisshoku Techno Fine Chemical Co., Ltd., diphenylic acid diallyl ester

[0287] Antioxidant A: manufactured by Sumitomo Chemical Co., Ltd., 2,6-di-tert-butyl-p-cresol

[0288] Oil Yellow GG-S: manufactured by ORIENT CHEMICAL INDUSTRIES, N,N-diethyl-4-(phenylazo)aniline

[0289] C.I. Solvent Green 3: manufactured by Wako Pure Chemical Industries, Ltd., 1,4-bis[(4-methylphenyl)amino]-9,10-anthraquinone

[0290] [Table 1]

[0291]

[0292] [Table 2]

[0293]

[0294] [Table 3]

[0295]

[0296] [Example 1]

[0297] Preparation of a sample for light DSC measurement

[0298] The photosensitive resin composition 1 was sandwiched with a release film (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation), and a 0.5 mm spacer was used to apply a pressure of 200 kg / cm 2 for 4 minutes at 120°C using a heat press, and then cooled to obtain a 10 cm long x 10 cm wide x 0.5 mm thick sample for DSC measurement.

[0299] <Manufacture of a flexographic printing plate under low-illuminance exposure conditions>

[0300] The photosensitive resin composition was fed into an extrusion molding machine, and the support layer obtained in the aforementioned [Manufacture Example] was attached to the surface of the layer of the photosensitive resin composition extruded from a T-shaped die, and a release film (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation) was attached to the surface of the layer of the photosensitive resin composition opposite to the side on which the support layer was laminated to obtain a laminate of the support and the layer of the photosensitive resin composition.

[0301] Next, the aforementioned release film was peeled off, and the laminate obtained in the aforementioned [Manufacture Example] for forming an infrared ablation layer was laminated so that the infrared ablation layer contacted the layer of the photosensitive resin composition to obtain a flexographic printing precursor having a thickness of 1.8 mm.

[0302] Next, the "AFP-1216" exposure machine was used to expose the flexographic printing precursor from the support (polyethylene terephthalate film) side so that the height of the cured pattern (RD) became about 0.7 mm.

[0303] Next, the cover film of the infrared ablation layer was peeled off, and the infrared ablation layer was drawn using the laser drawing machine "CDI Crystal 5080" manufactured by ESKO, and then the infrared ablation layer was irradiated with ultraviolet rays having an energy of 6000 mJ / cm 2 and an illuminance of 10 to 12 mW / cm 2 using the aforementioned exposure machine to perform image (relief) exposure.

[0304] Next, the "AFP-1321P" developing machine (trademark, manufactured by Asahi Chemical Industry Co., Ltd.) was used to develop at a liquid temperature of 30°C at a speed of 135 mm / min using SOLVIT (trademark, manufactured by MacDermid Co., Ltd., a mixed organic solvent in which a hydrocarbon is 60 mass% and an aliphatic alcohol is 40 mass%, and the boiling point is 155 to 205°C) as a developing solution, and dried at 60°C for 2 hours.

[0305] Subsequently, as a post-exposure treatment, the entire surface of the plate was irradiated with a germicidal lamp having a center wavelength of 254 nm at an energy of 2000 mJ / cm 2exposure of 1000 mJ / cm2using a UV fluorescent lamp. 2 exposure of 1000 mJ / cm2using a UV fluorescent lamp.

[0306] <Manufacture of a flexographic printing plate under high-illuminance exposure conditions>

[0307] The exposure machine used was "XPS Crystal 5080" manufactured by ESKO, and after the infrared ablation layer was drawn, exposure was performed from both the support body (polyethylene terephthalate film) side of the flexographic printing original plate and the infrared ablation layer side.

[0308] Note that, regarding the exposure conditions, "BFTH1.70(067)" built into the aforementioned exposure machine was used, and exposure was performed at an illuminance of 311 mW / cm2. 2

[0309] The flexographic printing plate was obtained by the same method as in the manufacture of the flexographic printing plate under low-illuminance exposure conditions, except for the other conditions.

[0310] [Examples 2 to 20, Comparative Examples 1 to 8]

[0311] The photosensitive resin composition used was changed as shown in Tables 4 to 6 below. The other conditions were the same as in Example 1, and a sample for light DSC measurement and a flexographic printing plate were obtained.

[0312] [Example 21]

[0313] The photosensitive resin composition used was changed, and the same operation as in Example 1 was performed to obtain a sample for light DSC measurement. Subsequently, the same operation as in Example 1 was performed on the flexographic printing original plate up to the exposure step, and the exposed flexographic printing original plate was fixed to a metal roller having a diameter of 35 cm that was operated by a motor using a double-sided adhesive tape.

[0314] A commercially available polyester nonwoven fabric was disposed in a manner that it could pass between a plurality of heatable metal rollers having a diameter of 5 cm.

[0315] An infrared lamp for more rapidly heating the photosensitive resin composition layer was fixed to the aforementioned metal roller that held the flexographic printing original plate.

[0316] The infrared lamp was turned on, and the metal roller that had been heated to 170°C was slowly (at about 2 rpm) rotated by a motor. The nonwoven fabric was passed on the metal roller while contacting the photosensitive resin composition surface of the flexographic printing original plate at a contact pressure of about 2.5 x 104Pa. 5

[0317] ​​The roll holding the flexo printing original plate was reciprocated 14 times to remove the uncured portion of the photosensitive resin composition layer by heat development, to obtain a flexo printing plate.

[0318] The photosensitive resin compositions used in Examples 2 to 21 and Comparative Examples 1 to 8 are shown in Tables 4 to 6, respectively.

[0319] [Method of Evaluation]

[0320] [Formability of high light dot under low illumination exposure condition]

[0321] The minimum formable dot was evaluated by observing the 1 to 10% dot of AM150 line on the obtained flexo printing plate using a microscope at 100 times.

[0322] The dot area ratio is the ratio (%) of the dot area per unit area, and the minimum formable dot means the minimum dot area ratio that can form a dot having a flat top portion without forming a defect at the top portion when the dot design drawn on the infrared ablation layer is used for plate making.

[0323] Note that the evaluation was performed according to the criteria shown below.

[0324] The evaluation results are shown in Tables 4 to 6.

[0325] [Criteria for Evaluation]

[0326] A: 1% or more and less than 2%

[0327] B: 2% or more and less than 2.5%

[0328] C: 2.5% or more and less than 3%

[0329] D: 3% or more and less than 4%

[0330] E: 4% or more

[0331] [Formability of intermediate style dot under high illumination exposure condition]

[0332] The top area ratio (AM150 line, 50% dot portion) of the intermediate style dot image portion on the flexo printing plate obtained in the above <Manufacture of flexo printing plate under high illumination exposure condition> was measured using FLEX3PRO (AVID FLEX Co., Ltd.).

[0333] As for the dot area ratio, considering that an expansion of about 10 to 20% occurs by actual printing, the smaller is better, and the evaluation was performed according to the criteria shown below.

[0334] The evaluation results are shown in Tables 4 to 6.

[0335] [Evaluation criteria]

[0336] A: Less than 49%

[0337] B: 49% or more and less than 51%

[0338] C: 51% or more and less than 52%

[0339] D: 52% or more and less than 53%

[0340] E: 53% or more

[0341] [Formability of independent dots under low-illuminance exposure conditions]

[0342] The independent dots on the obtained flexographic printing plate were observed with a magnifying glass, and the formability of the independent dots was evaluated.

[0343] The smallest independent dot that could be reproduced without being toppled in the developing step was set as the minimum independent dot, and the diameter of the independent dot design drawn on the infrared ablation layer in order to form the minimum independent dot was evaluated in accordance with the criteria shown below.

[0344] The evaluation results are shown in Tables 4 to 6.

[0345] [Evaluation criteria]

[0346] A: The minimum independent dot is 100 μm or less

[0347] B: The minimum independent dot is more than 100 μm and 150 μm or less

[0348] C: The minimum independent dot is more than 150 μm

[0349] Note that the smaller the minimum independent dot, the more accurately the fine image can be transferred, and it is evaluated that dense printing can be performed.

[0350] [Table 4]

[0351]

[0352] [Table 5]

[0353]

[0354] [Table 6]

[0355]

[0356] This application is based on Japanese Patent Application (Japanese Patent Application No. 2023-071540) filed in Japan Patent Office on April 25, 2023, and the content thereof is incorporated herein by reference.

[0357] Industrial Applicability

[0358] The flexible printing original plate of the present application has industrial applicability in the field of flexible printing plate manufacturing.

[0359] Explanation of Reference Numerals

[0360] (a) Support

[0361] (b) Photosensitive resin composition layer

[0362] (b') Printed pattern

[0363] (c) Infrared ablation layer

[0364] (c') Mask for the infrared ablation layer

Claims

1. A flexographic printing plate precursor which is a flexographic printing plate precursor of at least a support (a), a photosensitive resin composition layer (b), and an infrared ablation layer (c) stacked, For a 0.5 mm thick molded body of the photosensitive resin composition constituting the photosensitive resin composition layer (b), when performing differential scanning calorimetry at normal temperature and normal pressure while irradiating light of a wavelength of 365 nm at an irradiance of 10 mW / cm 2 2, the time from the start of irradiation to the exothermic peak was 4.0 seconds or more and 8.5 seconds or less, and the exothermic amount at the peak top was 1500 μW / mg or more and 3000 μW / mg or less.

2. The flexible printing master according to claim 1, wherein, the photosensitive resin composition layer (b) contains at least one or more selected from the group consisting of an ethylenically unsaturated compound (b-2), a photopolymerization initiator (b-3), a stabilizer (b-5), and a dye (b-6).

3. The flexographic printing precursor according to claim 2, wherein, the dye (b-6) contains a dye (B-6) having a 1,4-diamino-5,8-dihydroxyanthraquinone skeleton in the molecular structure.

4. The flexographic printing precursor according to claim 3, wherein, the dye (B-6) has a molecular structure represented by the following formula (1), in formula (1), R1, R2 each independently represents an alkyl group having 1 to 4 carbon atoms.

5. The flexographic printing precursor according to claim 4, wherein, 0.005 to 0.1% by mass of the dye having the molecular structure represented by the formula (1) is contained in the photosensitive resin composition layer (b).

6. The flexible printing precursor according to any one of claims 2 to 5, wherein, as the stabilizer (b-5), at least one stabilizer (B-5) is contained, which is a compound represented by the following formula (2) or (3), the content of the stabilizer (B-5) is 0.45% by mass or less of the photosensitive resin composition layer (b), in formula (2), (3), R3, R5 each independently represents an alkyl group having 1 to 4 carbon atoms, R4, R6 each independently represents an alkyl group having 1 to 12 carbon atoms.

7. The flexographic printing precursor according to claim 6, wherein the content of the stabilizer (B-5) is 60% by mass or more and 100% by mass or less of the total amount of the stabilizer (b-5).

8. The flexible printing precursor according to any one of claims 2 to 5, wherein, as the ethylenically unsaturated compound (b-2), an ethylenically unsaturated compound (B-2) having a structure represented by the following formula (4) is contained, in formula (4), R7, R8, and R9 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, * represents a bonding site.

9. The flexographic printing precursor according to claim 8, wherein, as the ethylenically unsaturated compound (B-2), a compound represented by the following formula (5) is contained, 。 10. A method for manufacturing a flexographic printing plate using the flexographic printing plate precursor according to any one of claims 1 to 5, the method having the following steps: a first step of irradiating ultraviolet rays from the support (a) side; a second step of performing laser ablation on the infrared ablation layer (c) provided on the photosensitive resin composition layer (b) to produce a negative pattern; a third step of performing pattern exposure by irradiating ultraviolet rays on the photosensitive resin composition layer (b) with the infrared ablation layer (c) on which the pattern is drawn as a mask; and a fourth step of removing the unexposed portion of the photosensitive resin composition layer (b).

11. The method of manufacturing a flexographic printing plate according to claim 10, wherein, In the fourth step of removing the unexposed portion of the photosensitive resin composition layer (b), solvent development is performed.

12. The method of manufacturing a flexographic printing plate according to claim 10, wherein, In the fourth step of removing the unexposed portion of the photosensitive resin composition layer (b), heat development is performed.

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