Flexographic printing original plate, method for manufacturing flexographic printing plate, flexographic printing plate, and flexographic printing method

Abstract

This flexographic printing original plate is obtained by laminating at least a support (a) and a photosensitive resin composition layer (b), and is characterized in that: the photosensitive resin composition layer (b) contains a cycloalkane hydrocarbon compound having a cycloalkane ratio of 60-80%, and satisfies the following lt; the condition is 1gt; . Lt; the condition is 1gt; a cured product obtained by molding a photosensitive resin composition constituting the photosensitive resin composition layer (b) to a thickness of 1.5 mm and irradiating the upper surface and the lower surface with 3,000 mJ ultraviolet light has a Shore A hardness of 60-75, and the storage modulus G '(MPa) and the loss modulus G "(MPa) of the cured product satisfy the following formulae (1) and (2) in a dynamic viscoelasticity measurement at-30 DEG C and 2.5 Hz. 1.04 < = G '+ G "< = 1.79 (1) 0.15 < = G" < = 0.30 (2).

Description

Technical Field

[0001] The present invention relates to a flexographic printing original plate, a method for producing a flexographic printing plate, a flexographic printing plate and a flexographic printing method. Background Art

[0002] Flexographic printing is an example of relief printing, which is a method in which water-based ink or solvent-based ink containing an ester solvent or the like is supplied to the convex surface of a resin plate having concave and convex portions using an ink supply roller or the like, and then the resin plate is brought into contact with a printed object to transfer the ink on the convex surface to the printed object, thereby performing printing.

[0003] In recent years, in the flexographic printing market, a flexographic printing plate capable of high-speed printing has been sought. During high-speed printing, the flexographic printing plate is more easily worn than during low-speed printing, and therefore, a flexographic printing plate with high hardness is generally used. However, when the hardness of the flexographic printing plate is high, there is a problem that the surface of the flexographic printing plate cannot completely follow the fine irregularities on the surface of the cardboard paper, and white spots may occur in the solid image portion due to poor ink transfer.

[0004] In order to solve the above-mentioned problems, methods of improving the blurring of solid image areas by controlling the characteristics of flexographic printing plates have been studied.

[0005] For example, Patent Document 1 considers that the cause of uneven printing concentration in flexible printing is the vibration of the flexible printing plate during printing. Instead of using the Shore A hardness as a static plate characteristic, the dynamic viscoelastic property is used to improve the uneven printing concentration by controlling the loss tangent (tanδ) of the photocured material contained in the flexible printing plate within a specified range.

[0006] Patent document 2 proposes a technology for suppressing the breakage of the halftone dots by adjusting the hardness of a cushioning material attached to the surface of a flexographic printing plate opposite to the surface on which a relief image is formed, thereby increasing the printing density of the solid image portion even in high-definition printed materials.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2007 / 058163

[0010] Patent Document 2: Japanese Patent Application Publication No. 2019-171730 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] However, the technology disclosed in Patent Document 1 is a technology discovered during low-speed printing at a printing speed of 80 m / min, and the technology disclosed in Patent Document 2 is also a control technology during low-speed printing. Therefore, from the perspective of improving the white spots that occur in the solid image portion during high-speed printing, such as printing at a printing speed of 450 m / min or more, there are problems that have not been fully studied.

[0013] Therefore, an object of the present invention is to provide a flexographic printing original plate capable of obtaining a flexographic printing plate having excellent abrasion resistance even in high-speed printing at a printing speed of 450 m / min or more and capable of suppressing the occurrence of white spots in solid image areas.

[0014] Solutions for solving problems

[0015] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that, in a flexographic printing plate having a photosensitive resin composition layer containing a cycloalkane-based hydrocarbon compound at a predetermined cycloalkane ratio, the above-mentioned problems can be solved by setting the Shore A hardness and dynamic viscoelastic properties of a cured product of the photosensitive resin composition layer to a predetermined range of values, thereby completing the present invention.

[0016] That is, the present invention is as follows.

[0017] [1] A flexographic printing plate comprising at least a support (a) and a photosensitive resin composition layer (b) laminated together,

[0018] The photosensitive resin composition layer (b) contains a cycloalkane hydrocarbon compound having a naphthene ratio of 60% to 80%, and satisfies the following <Condition 1>.

[0019] <Condition 1>

[0020] The photosensitive resin composition constituting the photosensitive resin composition layer (b) is molded into a 1.5 mm thick layer and irradiated with ultraviolet rays of 3000 mJ from the upper and lower surfaces respectively, and the Shore A hardness of the cured product obtained is 60 or more and 75 or less.

[0021] In the dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the storage modulus G' (MPa) and the loss modulus G" (MPa) of the cured product satisfy the following formulas (1) and (2).

[0022] 1.04≤G'+G”≤1.79 (1)

[0023] 0.15≤G”≤0.30 (2)

[0024] [2] The flexographic printing plate according to [1] above, wherein in a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the ratio of the loss modulus G" (MPa) of the cured product to the storage modulus G' (MPa) (tan δ = G" / G') satisfies the following formula (3).

[0025] 0.17≤tanδ≤0.20 (3)

[0026] [3] The flexographic printing plate according to [1] or [2], wherein the cycloalkane ratio of the cycloalkane-based hydrocarbon compound is 65% or more and 73% or less.

[0027] [4] The flexographic printing plate according to any one of [1] to [3] above, wherein the content of the cycloalkane-based hydrocarbon compound in the photosensitive resin composition layer (b) is 3% by mass or more and 20% by mass or less.

[0028] [5] The flexographic printing plate according to any one of [1] to [4], wherein the photosensitive resin composition layer (b) further comprises a liquid conjugated diene.

[0029] The content of the cycloalkane-based hydrocarbon compound is 91 mol% or more and 99 mol% or less relative to the total amount of the liquid conjugated diene and the cycloalkane-based hydrocarbon compound.

[0030] [6] A method for producing a flexographic printing plate, comprising the steps of:

[0031] The first step is to irradiate ultraviolet rays from the support (a) side;

[0032] The second step is to place a negative film on the photosensitive resin composition layer (b), or to laser ablate the infrared ablation layer (c) provided on the photosensitive resin composition layer (b) to produce a negative pattern;

[0033] A third step is to irradiate the photosensitive resin composition layer (b) with ultraviolet light through the negative film or the infrared ablation layer (c) having the pattern drawn thereon as a mask to perform pattern exposure; and

[0034] The fourth step is to remove the unexposed portion of the photosensitive resin composition layer (b).

[0035] [7] A flexographic printing plate comprising a cured product of a photosensitive resin composition,

[0036] The Shore A hardness of the cured product is 61 or more and 77 or less,

[0037] In the dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the storage modulus G' (MPa) and the loss modulus G" (MPa) satisfy the following equations (4) and (5).

[0038] 1.17≤G'+G”≤1.80 (4)

[0039] 0.17≤G”≤0.30 (5)

[0040] [8] A flexographic printing plate according to [7] above, wherein, in a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the ratio of the loss modulus G" (MPa) to the storage modulus G' (MPa) of the cured product of the photosensitive resin composition, tanδ = G" / G', further satisfies the following formula (6).

[0041] 0.17≤tanδ≤0.20 (6)

[0042] [9] A flexible printing method comprising the following steps:

[0043] An ink attaching step of attaching ink to convex portions of the flexographic printing plate using the flexographic printing plate described in [7] or [8] above; and

[0044] A transfer step of transferring the ink to a substrate.

[0045] Effects of the Invention

[0046] According to the present invention, it is possible to provide a flexographic printing original plate capable of obtaining a flexographic printing plate having excellent abrasion resistance even in high-speed printing at a printing speed of 450 m / min or more and capable of suppressing white blurring in solid image areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic cross-sectional view of the flexographic printing plate according to this embodiment.

[0048] Figure 2 This is a schematic diagram showing a method for producing a flexographic printing plate using the flexographic printing original plate of the present embodiment.

[0049] Figure 3 The relationship between the frequency of strain applied to the cured product of the photosensitive resin composition layer (b) in the flexographic printing original plate of Example 1 and the sum of the storage modulus and the loss modulus G'+G". DETAILED DESCRIPTION

[0050] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “this embodiment”) will be described in detail.

[0051] It should be noted that the following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. The present invention can be implemented with various modifications within the scope of the gist thereof.

[0052] 〔Flexographic printing plate〕

[0053] The flexographic printing plate of the present embodiment is formed by laminating at least a support (a) and a photosensitive resin composition layer (b).

[0054] The photosensitive resin composition layer (b) contains a cycloalkane hydrocarbon compound having a cycloalkane ratio of 60% or more and 80% or less, and satisfies the following <Condition 1>.

[0055] <Condition 1>

[0056] The photosensitive resin composition constituting the photosensitive resin composition layer (b) is molded into a 1.5 mm thick layer and irradiated with ultraviolet rays of 3000 mJ from the upper and lower surfaces respectively, and the Shore A hardness of the cured product obtained is 60 or more and 75 or less.

[0057] In the dynamic viscoelasticity measurement at -30°C and 2.5 Hz,

[0058] The storage modulus G' (MPa) and the loss modulus G" (MPa) of the aforementioned cured product satisfy the following formulas (1) and (2).

[0059] 1.04≤G'+G”≤1.79 (1)

[0060] 0.15≤G”≤0.30 (2)

[0061] With the above configuration, a flexographic printing plate can be produced which has excellent printing durability even at high-speed printing of, for example, 450 m / min or more, and can reduce and suppress the occurrence of white spots in solid image areas.

[0062] Figure 1 Schematic cross-sectional view of the flexographic printing original plate 1 of this embodiment is shown in FIG.

[0063] The flexographic printing plate of the present embodiment includes a support (a) and a photosensitive resin composition layer (b) that forms a concavo-convex pattern of the flexographic printing plate.

[0064] The flexographic printing plate 1 of the present embodiment may have a protective layer (see, for example, Japanese Patent Publication No. 5-13305) as necessary. The protective layer has a function of improving contact with a predetermined negative film and is solvent-soluble, thin, and flexible.

[0065] Figure 1In the flexographic printing plate of the present embodiment shown in , an infrared ablative layer (c) that functions as a mask when forming the above-mentioned concavo-convex pattern is laminated on the photosensitive resin composition layer (b).

[0066] In the flexographic printing plate of the present embodiment, other layers may be further provided between the layers as necessary.

[0067] Hereinafter, the flexographic printing original plate of this embodiment will be described.

[0068] (Support body (a))

[0069] The support (a) used in the flexographic printing plate of the present embodiment is not limited to the following, and examples thereof include polyester films, polyamide films, polyacrylonitrile films, polyvinyl chloride films, and the like.

[0070] The support (a) is preferably a polyester film.

[0071] The polyester used for the support (a) is not limited to the following ones, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0072] The thickness of the support (a) is not particularly limited, but is preferably 50 μm or more and 300 μm or less.

[0073] In order to improve the adhesion between the support (a) and the photosensitive resin composition layer (b) described later, an adhesive layer may be provided on the support (a). The adhesive layer is not limited to the following layers, and examples thereof include adhesive layers described in International Publication No. 2004 / 104701.

[0074] (Photosensitive resin composition layer (b))

[0075] As a result of intensive research, the present inventors have found that, from the viewpoint of achieving excellent abrasion resistance, reducing white spots in solid image areas and inhibiting the occurrence of white spots during high-speed printing, for example, at a printing speed of 450 m / min or more, it is important to focus on the storage modulus (G') and loss modulus (G") of the photosensitive resin composition layer (b) constituting the flexographic printing plate in the low temperature / low frequency region, and in particular to control the sum of G' and G" and G".

[0076] Generally speaking, the complex elastic modulus G related to the hardness of the flexographic printing plate at rest is * Use |G * |={(G') 2 +(G”) 2} 1 / 2This indicates that when the smaller value between G' and G", increases or decreases, the change in the absolute value of the complex elastic modulus is small, and no correlation with printing is observed. Therefore, when focusing on G'+G", which also equally reflects the change in the value of either G' or G", it can be seen that it has a good correlation with printing. This can be said to indicate that G' and G" need to be controlled more precisely during high-speed printing.

[0077] That is, in order to improve the printing characteristics during high-speed printing, since G" is significantly related to the blurring during high-speed printing, it is effective to apply the parameter G'+G" which can equally reflect the change of G" value and the change of G' value.

[0078] Figure 3 2 shows the results of preparing a master curve with the reference temperature set to 20° C. for the sample of Example 1 described later.

[0079] exist Figure 3 In the graph, the horizontal axis represents the frequency of strain applied to the cured product of the photosensitive resin composition layer (b), and the vertical axis represents the sum of the observed storage modulus and loss modulus G'+G".

[0080] like Figure 3 As shown, the higher the frequency, the higher G'+G" will be.

[0081] The convex part of the flexographic printing plate is subjected to stress when it contacts the printed object, but during high-speed printing, the period of the applied force becomes shorter, so the viscoelasticity of the photosensitive resin composition layer (b) also changes, corresponding to the high-frequency region. For example, it is expected that the flexographic printing speed will be further increased in the future. When focusing on high-speed printing with a printing speed of 600m / min, in a general printing machine, at 20°C, it can be estimated that the frequency of the force applied to the flexographic printing plate is 5000-6000Hz. According to the time-temperature equivalence principle, it is an area corresponding to -30°C and 2.5Hz, and it can be seen that the viscoelasticity of the photosensitive resin composition layer (b) corresponds to the low temperature / low frequency area. The area corresponding to -30°C and 2.5Hz is a region close to the glass transition temperature (Tg) region of the butadiene structure that is usually contained in order to make the flexographic printing original plate and the flexographic printing plate flexible. As the printing speed is higher, the cycle of the force applied to the flexographic printing plate becomes higher frequency. Therefore, according to the time-temperature equivalence principle, the viscoelasticity of the photosensitive resin composition layer (b) corresponds to the measurement area at a lower temperature, and as a result, it corresponds to a low temperature area close to the Tg of butadiene. As a result, the flexibility of the flexographic printing plate is impaired and the elastic modulus is increased, so the edge whitening is more likely to occur at higher printing speeds.

[0082] In order to achieve excellent abrasion resistance when high-speed printing is performed using the above-mentioned flexographic printing plate, reduce edge whitening during printing, and inhibit the occurrence of edge whitening, the photosensitive resin composition constituting the photosensitive resin composition layer (b) of the flexographic printing original plate is molded into a thickness of 1.5 mm and irradiated with 3000 mJ of ultraviolet rays from the upper surface and the lower surface respectively. In the dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the sum of the above G' and G", that is, G'+G", must be 1.04 or more and 1.79 or less.

[0083] Within the above numerical range, the level of end whitening is significantly optimized.

[0084] When G′+G″ is 1.04 or more, the flexographic printing plate can obtain excellent printing durability during high-speed printing.

[0085] Moreover, when it is 1.79 or less, the effect of fully suppressing edge whitening can be obtained.

[0086] From the viewpoint of achieving both improvement of edge whitening and printing durability, the G′+G″ is preferably 1.40 to 1.75, and more preferably 1.50 to 1.70.

[0087] In addition, in the flexographic printing plate of the present embodiment, in order to achieve excellent abrasion resistance, reduce white spots, and suppress the occurrence of white spots during high-speed printing, it is also necessary to control the loss modulus G".

[0088] When the printing speed is increased, the value of G" is related to the speed at which end whitening begins to occur.

[0089] The lower G” is, the less likely it is that edge whitening will occur during high-speed printing. This is considered to be because: G” is the loss modulus, which is related to plastic deformation. If the value of G” becomes large and deformation associated with printing occurs, it takes time for the shape of the flexible printing plate to recover, resulting in edge whitening.

[0090] In the present embodiment, G" is greater than or equal to 0.15 and less than or equal to 0.30. Within the above range, even in high-speed printing at a speed of more than 450 m / min, the effect of improving edge whitening can be achieved.

[0091] When G" is 0.30 or less, even in high-speed printing at 450 m / min or more, edge blurring can be effectively suppressed.

[0092] Since it is difficult to produce an object with a G" of less than 0.15, it is set to be 0.15 or more from a practical point of view.

[0093] In order to exhibit the effect even in higher-speed printing, G" is preferably 0.15 or more and 0.29 or less, and more preferably 0.15 or more and 0.24 or less.

[0094] In order to reduce G' and G" in the dynamic viscoelasticity measurement at -30°C and 2.5 Hz, it is effective to add a plasticizer having a specific structure described later to the photosensitive resin composition. The plasticizer having a specific structure can reduce the Tg of the butadiene structure in the photosensitive resin composition.

[0095] In addition, G" can be reduced by adjusting the composition of the thermoplastic elastomer (b-1) described later.

[0096] That is, by adjusting the composition of the plasticizer and the thermoplastic elastomer (b-1) described later, it is possible to control the value of the above formula (1) and formula (2) to fall within the range.

[0097] In addition, G' and G" can be measured by the method described in the Examples below.

[0098] In addition, in the flexible printing original plate of the present embodiment, in the dynamic viscoelasticity measurement at -30°C and 2.5 Hz as described above, the ratio of the aforementioned loss modulus G" (MPa) to the aforementioned storage modulus G' (MPa): tanδ = G" / G' is preferably greater than 0.17 and less than 0.20, more preferably greater than 0.17 and less than 0.19, and further preferably greater than 0.17 and less than 0.18.

[0099] When the value is within the above numerical range, the effect of improving edge blurring and suppressing the occurrence of edge blurring can be obtained during higher speed printing.

[0100] Tan δ can be controlled within the above numerical range by adjusting the composition of the plasticizer and the thermoplastic elastomer described later.

[0101] In the flexographic printing plate of the present embodiment, the Shore A hardness of the cured product of the 1.5 mm thick photosensitive resin composition layer (b) is set to 60 or more and 75 or less.

[0102] By setting the Shore A hardness of the cured product to be 60 or more, the flexographic printing plate can obtain sufficient printing resistance. In addition, by setting the Shore A hardness to be 75 or less, the flexographic printing plate can obtain sufficient flexibility, for example, the workability when the flexographic printing plate is wound on the plate body is good. From the viewpoint of taking into account both the printing resistance and flexibility of the flexographic printing plate, the Shore A hardness is 60 or more and 75 or less, preferably 62 or more and 73 or less, and more preferably 64 or more and 70 or less.

[0103] The Shore A hardness of the cured product can be measured by the method described in the examples below, and can be controlled within the above numerical range by adjusting the structure and content of the thermoplastic elastomer (b-1) contained in the photosensitive resin composition.

[0104] The flexographic printing plate of the present embodiment has a photosensitive resin composition layer (b) on a support (a).

[0105] The photosensitive resin composition layer (b) may be directly laminated on the support (a) or may be indirectly laminated via a predetermined adhesive layer or the like.

[0106] As the material of the photosensitive resin composition layer (b), for example, a photosensitive resin composition comprising a thermoplastic elastomer (b-1), an ethylenically unsaturated compound (b-2), a photopolymerization initiator (b-3), and a cycloalkane hydrocarbon compound (b-4) can be suitably cited. They can be appropriately selected and used. The photosensitive resin composition layer (b) may further contain a liquid diene. In addition, the photosensitive resin composition layer (b) may further contain auxiliary additives as required.

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

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

[0109] Thermoplastic elastomer (b-1) is not limited to the following substances, and for example, copolymers having structural units derived from monovinyl-substituted aromatic hydrocarbons and structural units derived from conjugated dienes can be cited. It should be noted that the thermoplastic elastomer (b-1) may also have structural units derived from other monomers. By using such a thermoplastic elastomer, there is a tendency that the printing resistance of the flexographic printing plate manufactured using the flexographic printing original plate of the present embodiment is further improved.

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

[0111] By using such a thermoplastic elastomer, the printing durability of the flexographic printing plate produced using the flexographic printing original plate of the present embodiment tends to be further improved.

[0112] The monovinyl-substituted aromatic hydrocarbon constituting the thermoplastic elastomer (b-1) is not limited to the following substances, and examples thereof include styrene, tert-butylstyrene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, p-methoxystyrene, tert-butylstyrene, α-methylstyrene, 1,1-diphenylethylene, etc. These may be used alone or in combination of two or more.

[0113] Among them, styrene is preferred as the monovinyl-substituted aromatic hydrocarbon from the viewpoint of being able to smoothly mold the photosensitive resin composition layer (b) at a relatively low temperature.

[0114] The conjugated diene constituting the thermoplastic elastomer (b-1) is not limited to the following substances, and examples thereof include 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, chloroprene, etc. These may be used alone or in combination of two or more.

[0115] Among them, from the viewpoint of the printing durability of the flexographic printing plate produced using the flexographic printing original plate of the present embodiment, 1,3-butadiene is preferred as the conjugated diene.

[0116] The number average molecular weight (Mn) of the thermoplastic elastomer (b-1) is preferably 20,000 to 300,000, more preferably 50,000 to 200,000, from the viewpoint of viscosity at room temperature. The number average molecular weight can be measured by gel permeation chromatography (GPC) and is expressed as a polystyrene-equivalent molecular weight.

[0117] When the thermoplastic elastomer (b-1) is a block copolymer having a polymer block formed of a monovinyl-substituted aromatic hydrocarbon and a polymer block formed of a conjugated diene, the thermoplastic elastomer (b-1) includes, for example, a linear block copolymer represented by the following general formula group (I) and / or a linear block copolymer or a radial block copolymer represented by the following general formula group (II).

[0118] General formula group (I):

[0119] (AB) n 、A-(BA) n 、A-(BA) n -B, B-(AB) n

[0120] General formula group (II):

[0121] [(AB) k ] m -X, [(AB) k -A] m -X, [(BA) k ] m -X, [(BA) k -B] m -X

[0122] In the general formula groups (I) and (II), A represents a polymer block formed of a monovinyl-substituted aromatic hydrocarbon. In addition, B represents a polymer block formed of 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, halogenated silane compounds and ester compounds, or a residue of a polymerization initiator such as a multifunctional organic lithium compound.

[0123] In the general formulae (I) and (II), n, k and m represent an integer greater than or equal to 1, for example, 1-5.

[0124] The content of conjugated diene and monovinyl-substituted aromatic hydrocarbon in the thermoplastic elastomer (b-1) can be measured using a nuclear magnetic resonance apparatus ( 1 Specifically, JNM-LA400 (manufactured by JEOL, trade name) can be used as 1 The H-NMR measuring equipment used deuterated chloroform as solvent, set the sample concentration to 50 mg / mL, set the observation frequency to 400 MHz, use TMS (tetramethylsilane) as the chemical shift standard, set the pulse delay to 2.904 seconds, set the number of scans to 64 times, set the pulse width to 45°, and set the measuring temperature to 25°C for measurement.

[0125] In the thermoplastic elastomer (b-1), if the ratio of monovinyl-substituted aromatic hydrocarbons is reduced, the hardness of the flexographic printing plate manufactured using the flexographic printing original plate of the present embodiment is reduced, and therefore, the flexibility of the flexographic printing plate is improved. On the other hand, if the ratio of monovinyl-substituted aromatic hydrocarbons is increased, the hardness of the flexographic printing plate increases, and therefore, the printing resistance of the flexographic printing plate is improved. From the viewpoint of taking into account the flexibility and printing resistance of the flexographic printing plate, the copolymerization ratio (mass ratio) of monovinyl-substituted aromatic hydrocarbons and conjugated dienes is preferably in the range of monovinyl-substituted aromatic hydrocarbons / conjugated dienes = 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.

[0126] In the thermoplastic elastomer (b-1), if the ratio of double bonds located in the side chains among the double bonds contained in the polymer block formed of a conjugated diene is reduced, the loss modulus G" of the cured product obtained by molding the photosensitive resin composition of the photosensitive resin composition layer (b) constituting the flexographic printing plate of the present embodiment into a thickness of 1.5 mm and subjecting it to ultraviolet curing at -30°C and 2.5 Hz is reduced. Therefore, from the viewpoint of controlling the dynamic viscoelasticity, in the structure of the thermoplastic elastomer (b-1), the molar ratio of the amount of double bonds located in the side chains among all the double bonds contained in the polymer block formed of a 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.

[0127] The ratio of the amount of double bonds contained in the main chain and the amount of double bonds contained in the side chain of the polymer block composed of conjugated diene in the thermoplastic elastomer (b-1) can be measured using the above-mentioned nuclear magnetic resonance apparatus ( 1 H-NMR) to calculate.

[0128] By increasing the content of the thermoplastic elastomer (b-1) in the photosensitive resin composition layer (b), there is a tendency to improve the printing resistance of the flexographic printing plate manufactured using the flexographic printing original plate of the present embodiment. 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 therefore, the flexibility of the flexographic printing plate is improved. From the viewpoint of taking into account the printing resistance and flexibility of the flexographic printing plate, when the total amount of the photosensitive resin composition layer (b) is set to 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.

[0129] <Ethylenically Unsaturated Compound (b-2)>

[0130] As described above, the photosensitive resin composition layer (b) preferably contains an ethylenically unsaturated compound (b-2). The ethylenically unsaturated compound (b-2) is a compound having an unsaturated double bond that can undergo radical polymerization.

[0131] Such ethylenically unsaturated compounds (b-2) are not limited to the following substances, and examples thereof include olefins such as ethylene, propylene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene, styrene, o-divinylbenzene, m-vinylbenzene, p-vinylbenzene, etc.; acetylenes; (meth)acrylic acid and / or its derivatives; halogenated olefins; unsaturated nitriles such as acrylonitrile; unsaturated amides such as acrylamide and methacrylamide, and their derivatives; unsaturated dicarboxylic acids such as maleic anhydride, maleic acid, fumaric acid, and their derivatives; vinyl acetates; N-vinylpyrrolidone; N-vinylcarbazole; N-substituted maleimide compounds, etc.

[0132] Among them, from the viewpoint of ultraviolet curability and the printing durability of the photosensitive resin composition layer (b) after curing, the ethylenically unsaturated compound (b-2) is preferably (meth)acrylic acid and / or a derivative thereof.

[0133] The aforementioned derivatives are not limited to the following substances, and examples thereof include alicyclic compounds having cycloalkyl, bicycloalkyl, cycloalkenyl, bicycloalkenyl, etc.; aromatic compounds having benzyl, phenyl, phenoxy or naphthalene skeletons, anthracene skeletons, biphenyl skeletons, phenanthrene skeletons, fluorene skeletons, etc.; compounds having alkyl, halogenated alkyl, alkoxyalkyl, hydroxyalkyl, aminoalkyl, glycidyl, etc.; ester compounds formed with polyols such as alkylene glycol, polyoxyalkylene glycol, polyalkylene glycol, trimethylolpropane, etc.; compounds having a polysiloxane structure such as polydimethylsiloxane and polydiethylsiloxane, etc.

[0134] Furthermore, the ethylenically unsaturated compound (b-2) may be a heteroaromatic compound containing elements such as nitrogen and sulfur.

[0135] The aforementioned (meth)acrylic acid and / or its derivatives are not limited to the following substances, and examples thereof include diacrylates and dimethacrylates of alkane diols such as hexanediol and nonanediol; diacrylates and dimethacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, and butanediol; trimethylolpropane tri(meth)acrylate; dimethyloltricyclodecane di(meth)acrylate; isobornyl (meth)acrylate; phenoxypolyethylene glycol (meth)acrylate; pentaerythritol tetra(meth)acrylate, etc.

[0136] These may be used alone or in combination of two or more.

[0137] From the viewpoint of mechanical strength of the flexographic printing plate produced using the flexographic printing original plate of this embodiment, it is preferred to use at least one (meth)acrylate as the ethylenically unsaturated compound (b-2), and it is more preferred to use at least one difunctional (meth)acrylate.

[0138] From the viewpoint of improving the non-volatility of the ethylenically unsaturated compound (b-2) during manufacture and / or storage of the flexible printing plate of this embodiment, the number average molecular weight (Mn) of the ethylenically unsaturated compound (b-2) is preferably greater than 100, and from the viewpoint of compatibility with other components, it is preferably less than 1000, and more preferably greater than 200 and less than 800.

[0139] About the content of ethylenically unsaturated compound (b-2) in photosensitive resin composition layer (b), by reducing the content of ethylenically unsaturated compound (b-2), the hardness of the flexographic printing plate manufactured using the flexographic printing original plate of the present embodiment is reduced, and the flexibility of the flexographic printing plate is improved. On the other hand, by increasing the content of ethylenically unsaturated compound (b-2), the hardness of the flexographic printing plate rises, and therefore, the printing resistance is improved. From the viewpoint of taking into account the flexibility and printing resistance of the flexographic printing plate, when the total amount of the photosensitive resin composition layer (b) is set to 100.0 mass %, the content of ethylenically unsaturated compound (b-2) is preferably 2.0 mass % or more and 25.0 mass % or less, more preferably 5.0 mass % or more and 20.0 mass % or less.

[0140] Furthermore, from the viewpoint of the viscoelasticity of the cured product obtained by molding the photosensitive resin composition layer (b) constituting the flexographic printing plate of the present embodiment into a thickness of 1.5 mm, by reducing the content of the ethylenically unsaturated compound (b-2), G'+G" at -30°C and 2.5 Hz becomes smaller. Therefore, the content of the ethylenically unsaturated compound (b-2) in the photosensitive resin composition layer (b) is further preferably 5.0% by mass or more and 15.0% by mass or less.

[0141] <Photopolymerization Initiator (b-3)>

[0142] The photosensitive resin composition layer (b) preferably contains a photopolymerization initiator (b-3). The photopolymerization initiator (b-3) refers to a compound that absorbs light energy and generates free radicals, and examples thereof include a collapse-type photopolymerization initiator, a hydrogen abstraction-type photopolymerization initiator, and a compound having a site that functions as a hydrogen abstraction-type photopolymerization initiator and a site that functions as a collapse-type photopolymerization initiator in the same molecule.

[0143] The photopolymerization initiator (b-3) is not limited to the following substances, and examples thereof include benzophenones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 3,3',4,4'-benzophenonetetracarboxylic anhydride, and 3,3',4,4'-tetramethoxybenzophenone; anthraquinones such as tert-butylanthraquinone and 2-ethylanthraquinone; thioxanthones such as 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; Michler's ketone; diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propane-1 -ketone, 2-methyl-1-(4-methylthienyl)-2-morpholinyl-propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone, trichloroacetophenone and other acetophenones; benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and other benzoin ethers; acyl phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; methyl benzoyl formate; 1,7-bisacridinylheptane; 9-phenylacridine; azo compounds such as azobisisobutyronitrile, diazo compounds, tetrazene compounds, etc.

[0144] These may be used alone or in combination of two or more.

[0145] Among them, from the viewpoint of the hardness of the flexographic printing plate produced using the flexographic printing original plate of this embodiment, the photopolymerization initiator (b-3) is preferably a compound having a carbonyl group, and more preferably an aromatic carbonyl compound such as benzophenones and thioxanthones.

[0146] If the content of the photopolymerization initiator (b-3) in the photosensitive resin composition layer (b) is reduced, the hardness of the flexographic printing plate manufactured using the flexographic printing original plate of the present embodiment is reduced, and the flexibility of the flexographic printing plate is improved. On the other hand, if the content of the photopolymerization initiator (b-3) is increased, the hardness of the flexographic printing plate increases, and therefore, the printing resistance of the flexographic printing plate is improved. From the viewpoint of taking into account the flexibility and printing resistance of the flexographic printing plate, 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.

[0147] <Cycloalkane hydrocarbon compound (b-4)>

[0148] In the flexographic printing plate of the present embodiment, the photosensitive resin composition layer (b) contains a cycloalkane-based hydrocarbon compound.

[0149] Cycloalkane hydrocarbon compounds are hydrocarbons containing at least one saturated ring (cycloalkane ring) in one molecule. n H 2n The cycloalkane hydrocarbon compounds present in crude oil and petroleum products include compounds formed by connecting two or three cycloalkane rings, compounds formed by condensing with aromatic rings, and compounds formed by connecting various alkane side chains to cycloalkane rings and condensed rings.

[0150] The cycloalkane hydrocarbon compound has at least one cycloalkane ring in one molecule and has a stereoscopically large molecular structure. Therefore, compared with the block formed by the styrene polymer having a π-π stacking structure in the thermoplastic elastomer (b-1), the block formed by the butadiene polymer having a high degree of freedom of molecular movement is preferentially plasticized.

[0151] As the plasticizer used in the flexographic printing plate of the present embodiment, a cycloalkane-based hydrocarbon compound that preferentially plasticizes the block composed of a butadiene polymer in the thermoplastic elastomer (b-1) is used from the viewpoint of cold flow resistance of the flexographic printing plate of the present embodiment.

[0152] In the flexographic printing plate of the present embodiment, when a cycloalkane-based hydrocarbon compound is used in the photosensitive resin composition (b), if the ratio of cycloalkane rings in the cycloalkane-based hydrocarbon compound (hereinafter referred to as the cycloalkane ratio) becomes small, the block composed of the styrene polymer in the thermoplastic elastomer (b-1) is also plasticized, and the cold flow resistance is deteriorated.

[0153] On the other hand, if the cycloalkane ratio is too large, the stereo hindrance becomes large, so there is a tendency that the effect of plasticizing the block formed by the butadiene polymer in the thermoplastic elastomer (b-1) is weakened, and it is difficult to control the low-temperature viscoelasticity of the photosensitive resin composition (b). Therefore, the cycloalkane ratio in the cycloalkane-based hydrocarbon compound is set to 60% to 80%, preferably 65% ​​to 73%, and more preferably 67% to 71%.

[0154] The cycloparaffin ratio is the ratio of VGC (viscosity specific gravity constant) and r obtained by measuring according to the Kurtz method based on ASTM D2140-08 (2017). i (Refractive index) The value derived (the percentage of the number of cycloalkane carbon atoms relative to the total number of carbon atoms: cycloalkane ratio).

[0155] In addition, in order to extract the cycloalkane-based hydrocarbon compound from the flexographic printing original plate of the present embodiment, the following method was used.

[0156] [Method for extracting cycloalkane hydrocarbon compounds]

[0157] The photosensitive resin composition on the flexographic printing plate was dissolved in tetrahydrofuran, and the fraction having a peak molecular weight (Mp) of 500 or more and 2000 or less was separated by gel chromatography (GPC) using the following apparatus and conditions, thereby extracting cycloalkane hydrocarbon compounds from the flexographic printing plate.

[0158] Equipment: WATERS, ALLIANCE GPC

[0159] Column: Connect four of the following columns in series to separate cycloparaffinic hydrocarbon compounds.

[0160] SHODEX KF-801 x 2, KF-802 and KF-803 manufactured by Showa Denko

[0161] Column temperature: 40°C

[0162] Solvent: Tetrahydrofuran

[0163] Detector: SHODEXRI-101 manufactured by Showa Denko Co., Ltd.

[0164] Standard curve: Standard polystyrene

[0165] In the flexographic printing plate of the present embodiment, the content of the cycloalkane-based hydrocarbon compound in the photosensitive resin composition layer (b) is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less, and further preferably 7% by mass or more and 13% by mass or less.

[0166] By setting the content to be 3% by mass or more, it is possible to obtain an effect of reducing the degree of edge blurring during high-speed printing.

[0167] By setting the content to be 20% by mass or less, it is possible to obtain an effect of improving the printing durability of a plate during high-speed printing.

[0168] In addition, in order to control the tanδ of the cured product obtained by molding the photosensitive resin composition layer (b) constituting the flexible printing original plate of the present embodiment into a thickness of 1.5 mm to a numerical range of not less than 0.17 and not more than 0.20 at -30°C and 2.5 Hz, the content of the cycloalkane-based hydrocarbon compound is preferably not less than 91 mol% and not more than 99 mol%, more preferably not less than 94 mol% and not more than 99 mol%, and further preferably not less than 96 mol% and not more than 99 mol%.

[0169] In addition, in the photosensitive resin composition layer (b), other compounds may be used in combination as a plasticizer.

[0170] Examples of other compounds include, but are not limited to, paraffinic hydrocarbon compounds, olefinic hydrocarbon compounds, and cycloparaffinic hydrocarbon compounds.

[0171] Chain alkane hydrocarbon compounds are compounds with the molecular formula C n H 2n+2 Saturated chain compounds include unbranched normal alkanes and branched isoalkanes.

[0172] Olefin hydrocarbon compounds are chain hydrocarbons with double bonds. When there is one double bond, C n H 2n It can be expressed by the general formula of .

[0173] <Liquid Diene>

[0174] The photosensitive resin composition layer (b) preferably contains a liquid diene.

[0175] Liquid diene refers to a liquid compound having a carbon-carbon double bond.

[0176] Here, in the present specification, the "liquid" of "liquid diene" means that the liquid diene has a property of being easily deformed by flow and being solidified into a deformed shape by cooling. The liquid diene has an elastomeric property of instantly deforming in accordance with an external force when the external force is applied, and restoring to the original shape in a short time when the external force is removed.

[0177] The liquid diene can be distinguished from the aforementioned thermoplastic elastomer (b-1) and ethylenically unsaturated compound (b-2) in that they are liquid at room temperature and have elastomeric properties.

[0178] The liquid diene is not limited to the following substances, and examples thereof include liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, and liquid styrene-butadiene copolymer.

[0179] The liquid diene is a copolymer containing 50% by mass or more of a diene component.

[0180] Among them, from the viewpoint of the mechanical properties of the flexographic printing original plate of the present embodiment and the flexographic printing plate produced using the same, liquid polybutadiene is preferred as the liquid diene.

[0181] In addition, from the viewpoint of making the hardness of the flexographic printing plate of the present embodiment and the flexographic printing plate manufactured using the same an appropriate value, the 1,2-vinyl bond content of the liquid diene, preferably the liquid polybutadiene, is preferably from 1% to 80%, more preferably from 5% to 70%, and further preferably from 5% to 65%.

[0182] Here, the "1,2-vinyl bond amount" refers to the ratio of bonds incorporated in the form of 1,2-bonds among the conjugated diene monomers incorporated in the form of 1,2-bonds and 1,4-bonds. The 1,2-vinyl bond amount can be calculated based on the amount of liquid polybutadiene. 1 The peak ratio of H-NMR (magnetic resonance spectrum) was used to determine the peak ratio.

[0183] In addition, in 1,2-polybutadiene which is a liquid polybutadiene having a 1,2-vinyl bond, the vinyl group as a double bond is a side chain, and therefore the radical polymerization reactivity is high, and it is preferred from the viewpoint of improving the hardness of the photosensitive resin composition layer (b).

[0184] In addition, liquid polybutadiene is usually a mixture of 1,2-polybutadiene having a 1,2-vinyl bond and 1,4-polybutadiene having a 1,4-vinyl bond. In order to improve the flexibility of the flexographic printing plate of the present embodiment and the flexographic printing plate manufactured using the same, it is effective to contain 1,4-polybutadiene in the liquid diene. 1,4-polybutadiene exists in cis-type 1,4-polybutadiene and trans-type 1,4-polybutadiene. Whether cis-type or trans-type, 1,4-polybutadiene has a vinyl group as a double bond inside, so it has low reactivity in free radical polymerization and can form a soft resin.

[0185] When a plurality of liquid polybutadienes having different 1,2-vinyl bond amounts are mixed and used, the average value thereof is defined as the 1,2-vinyl bond amount.

[0186] From the viewpoint of being able to easily adjust the reactivity of the photosensitive resin composition layer (b), it is preferred to adjust the overall 1,2-vinyl bond content by mixing a liquid polybutadiene having a 1,2-vinyl bond content of 10% or less and a liquid polybutadiene having a 1,2-vinyl bond content of 80% or more. It is more preferred to adjust the overall 1,2-vinyl bond content by mixing a liquid polybutadiene having a 1,2-vinyl bond content of 5% or less and a liquid polybutadiene having a 1,2-vinyl bond content of 80% or more.

[0187] In addition, the number average molecular weight of the liquid diene is not particularly limited as long as it is liquid at 20°C. From the viewpoint of printing resistance and handling properties of the flexographic printing plate manufactured using the flexographic printing original plate of this embodiment, it is preferably 500 to 60,000, more preferably 500 to 50,000, and further preferably 800 to 50,000.

[0188] If the content of liquid diene in the photosensitive resin composition layer (b) is reduced, the tan δ of the cured product obtained by molding the photosensitive resin composition layer (b) constituting the flexographic printing original plate of the present embodiment into a thickness of 1.5 mm at -30°C and 2.5 Hz is reduced. Therefore, when the total amount of the photosensitive resin composition layer (b) is set to 100.0% by mass, the content of liquid diene in the photosensitive resin composition layer (b) is preferably 5.0% by mass or more and 30.0% by mass or less, more preferably 5.0% by mass or more and 25.0% by mass or less, and further preferably 5.0% by mass or more and 20.0% by mass or less.

[0189] <Auxiliary additives>

[0190] The auxiliary additive components are not limited to the following, and examples thereof include a heat-resistant polymerization inhibitor, an antioxidant, an ultraviolet absorber, a dye, and a pigment, excluding a stabilizer.

[0191] As the heat-resistant polymerization agent and the antioxidant, those generally used in the field of resin materials or rubber materials can be used. Specifically, phenolic materials can be mentioned.

[0192] Such phenolic materials are not limited to the following substances, and examples thereof include vitamin E, tetrakis(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.

[0193] The heat-resistant polymerization agent and the antioxidant may be used alone or in combination of two or more.

[0194] The ultraviolet absorber is not limited to the following, and examples thereof include known benzophenone compounds, salicylate compounds, acrylonitrile compounds, metal complex salt compounds, and hindered amine compounds.

[0195] In addition, the dyes / pigments shown below can be used as ultraviolet absorbers.

[0196] Such ultraviolet absorbers are not particularly limited, and examples thereof include 2-ethoxy-2′-ethyloxalanilide and 2,2′-dihydroxy-4-methoxybenzophenone.

[0197] Dyes and pigments are effective as coloring means for improving visibility.

[0198] Dyes are not limited to the following substances, and examples thereof include water-soluble basic dyes, acid dyes, direct dyes, etc., and water-insoluble sulfur dyes, oil-soluble dyes, disperse dyes, etc. In particular, anthraquinone dyes, indigo dyes, and azo dyes are preferred, and azo oil-soluble dyes are more preferred.

[0199] The pigment is not limited to the following substances, and examples thereof include natural pigments, synthetic inorganic pigments, synthetic organic pigments, etc. Examples of synthetic organic pigments include azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, and phthalocyanine pigments.

[0200] When the total amount of the photosensitive resin composition layer (b) is 100.0 mass %, the total amount of the auxiliary additive components is preferably 0.1 mass % to 10.0 mass %, more preferably 0.1 mass % to 5.0 mass %, and even more preferably 0.1 mass % to 3.0 mass %.

[0201] (Protective layer)

[0202] The photosensitive resin composition constituting the photosensitive resin composition layer (b) generally has adhesiveness. Therefore, in order to improve the contact with the negative film superimposed thereon during the making of a flexographic printing plate, or to enable the reuse of the negative film, a solvent-soluble protective layer may be provided on the surface of the photosensitive resin composition layer (b).

[0203] The protective layer preferably contains a substance soluble in a solvent used as a washing solution, and is thin and flexible.

[0204] As the protective layer, for example, a protective layer comprising crystalline 1,2-polybutadiene, soluble polyamide, partially saponified polyvinyl acetate, cellulose ester, etc. can be listed, among which soluble polyamide is preferred. These substances can be dissolved in a suitable solvent and the solution can be directly applied to the surface of the photosensitive resin composition layer (b), or can be temporarily applied to a film such as polyester or polypropylene, and the film coated with the above substances can be laminated to the photosensitive resin composition layer (b) to transfer it.

[0205] (Infrared ablation layer (c))

[0206] In the flexographic printing plate of the present embodiment, an infrared ablative layer (c) containing an infrared sensitive substance may be laminated on the photosensitive resin composition layer (b) instead of the protective layer.

[0207] The infrared ablative layer (c) is preferably composed of a binder polymer, an infrared sensitive substance, and a non-infrared radiation shielding substance.

[0208] Examples of the binder polymer include polyamides, polyesters, and copolymers of monovinyl-substituted aromatic hydrocarbons and conjugated dienes, etc. Among them, copolymers of monovinyl-substituted aromatic hydrocarbons such as styrene, α-methylstyrene, and vinyltoluene and conjugated dienes such as 1,3-butadiene and isoprene are preferred.

[0209] When the infrared ablation layer (c) is constituted by using the aforementioned binder polymer, the affinity with the photosensitive resin composition is high and the adhesion is good.

[0210] When a polyester is used as the binder polymer, the number average molecular weight of the polyester is preferably 300 or more and 10,000 or less.

[0211] Furthermore, polyesters may be preferably polyesters synthesized from alkane diol and adipic acid, polyesters synthesized from alkane diol and phthalic acid, polycaprolactone, and combinations of two or more of these polyesters, etc. In addition, the polyester may contain various functional groups such as amino groups, nitro groups, sulfonic acid groups, and halogen groups within a range that does not impair compatibility with other binder polymers, infrared sensitive substances, and non-infrared radiation shielding substances.

[0212] As the infrared sensitive substance, for example, a monomer or compound having strong absorption in the range of 750 to 2000 nm can be preferably used.

[0213] Specific examples of the infrared sensitive substance include inorganic pigments such as carbon black, graphite, copper chromite, and chromium oxide; and pigments such as polyphthalocyanine compounds, cyanine pigments, and metal thiolate pigments.

[0214] These infrared sensitive substances are added within a range that provides sensitivity that enables ablation by the laser beam used. Generally, adding 10 to 80% by mass is effective.

[0215] As the shielding material of non-infrared radiation, a material that reflects or absorbs radiation such as ultraviolet radiation can be used. Ultraviolet radiation absorbers, carbon black, graphite, etc. are preferred examples thereof, and the amount added is set in a manner that can achieve the desired optical density. Generally speaking, it is preferably added in a manner that the optical density becomes 2 or more, preferably 3 or more.

[0216] [Method for producing flexographic printing plate]

[0217] The method for manufacturing a flexographic printing plate of the present embodiment uses the flexographic printing original plate of the present embodiment, and first has the following steps: a first step of irradiating ultraviolet rays from the support (a) side; a second step of placing a negative film on the photosensitive resin composition layer (b), or laser ablating the infrared ablation layer (c) provided on the photosensitive resin composition layer (b) by infrared irradiation to produce a negative pattern; a third step of irradiating the photosensitive resin composition layer (b) with ultraviolet rays through the aforementioned negative film or using the aforementioned infrared ablation layer (c) on which the aforementioned pattern is drawn and processed as a mask to perform pattern exposure; and a fourth step of removing the unexposed portion of the aforementioned photosensitive resin composition layer (b).

[0218] Thereafter, a post-exposure treatment step is performed as necessary to obtain a flexographic printing plate (relief printing plate) based on a cured product of the photosensitive resin composition layer (b).

[0219] From the viewpoint of imparting releasability to the ink or printed material, the surface of the flexographic printing plate may be brought into contact with a liquid containing an organic silicon compound and / or a fluorine compound.

[0220] Figure 2 A schematic diagram showing a method for producing a flexographic printing plate using a flexographic printing original plate according to the present embodiment is shown in FIG.

[0221] (First step: S1)

[0222] In the first step, the method of irradiating the photosensitive resin composition layer (b) with ultraviolet rays from the support (a) side is not particularly limited, and a known irradiation unit can be used. The wavelength of the ultraviolet rays irradiated is preferably 150 to 500 nm, more preferably 300 to 400 nm.

[0223] The ultraviolet light source is not limited to the following light sources, 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 zirconium lamp, a carbon arc lamp, an ultraviolet fluorescent lamp, etc. can be used.

[0224] It should be noted that the first step may be performed before the second step described below, or may be performed after the second step.

[0225] (Second step: S2)

[0226] In the second step, the method of irradiating the infrared ablation layer (c) with infrared rays to draw the pattern is not particularly limited, and a known irradiation unit can be used. It should be noted that the infrared ablation layer (c) can be irradiated with infrared rays from the infrared ablation layer (c) side.

[0227] When the flexographic printing plate of this embodiment has a cover film, the cover film is first peeled off before infrared irradiation. Thereafter, infrared rays are irradiated to the infrared ablation layer (c) pattern to decompose the resin in the infrared irradiation part and draw the pattern. Thus, a mask (c') of the infrared ablation layer (c) can be formed on the photosensitive resin composition layer (b).

[0228] In the second step, suitable infrared lasers include, for example, ND / YAG lasers (e.g., 1064 nm) or diode lasers (e.g., 830 nm). Laser systems suitable for CTP platemaking technology are already on the market, and for example, a diode laser system CDI Spark (ESKO GRAPHICS) can be used. The laser system includes: a rotating cylindrical drum holding the flexographic printing original plate of this embodiment, an IR laser irradiation device, and a layout computer, and image information is directly transmitted from the layout computer to the laser device.

[0229] (Third step: S3)

[0230] In the third step, the infrared ablation layer (c) with a pattern is used as a mask to irradiate the photosensitive resin composition layer (b) with ultraviolet rays, perform pattern exposure, and form a printed pattern (b'). At this time, the light passing through the mask will promote the curing reaction of the photosensitive resin composition layer (b), and the concave and convex patterns formed on the infrared ablation layer (c) will be reversed and transferred to the photosensitive resin composition layer (b). Regarding the irradiation of ultraviolet rays, the entire surface of the flexible printing original plate of this embodiment can be irradiated.

[0231] The third step can be performed while the flexographic printing plate of this embodiment is mounted on a laser cylinder. Generally, the flexographic printing plate of this embodiment is removed from the laser device and irradiated using a conventional irradiation unit. The irradiation unit can be the same as the unit exemplified in the ultraviolet irradiation of the first step.

[0232] (Fourth step: S4)

[0233] The fourth step is a step of removing the unexposed portion of the infrared ablation layer (b) and the photosensitive resin composition layer (c).

[0234] The removal method in the fourth step (development step) is not particularly limited, and a conventionally known method can be applied.

[0235] Specifically, as described above, the photosensitive resin composition layer (b) of the flexographic printing plate of the present embodiment is exposed to form a printed pattern (b'), and then the unexposed portion is removed by washing it with a solvent for solvent development or a cleaning solution for water development, or by bringing it into contact with a predetermined absorption layer capable of absorbing the unexposed portion heated to 40° C. to 200° C. and removing the absorption layer.

[0236] Thereafter, a post-exposure treatment is performed as necessary to produce a flexographic printing plate.

[0237] In addition, when there is an intermediate layer (d) between the infrared ablation layer (c) and the photosensitive resin composition layer (b), they can be removed simultaneously in the development step.

[0238] The developing solvent used for solvent development of the unexposed portion is not limited to the following solvents, and examples thereof include esters such as heptyl acetate and 3-methoxybutyl acetate; hydrocarbons such as petroleum fractions, toluene, and decalin; and solvents in which alcohols such as propanol, butanol, and pentanol are mixed in chlorinated organic solvents such as tetrachloroethylene. The unexposed portion is washed off by spraying from a nozzle or by brushing with a brush.

[0239] As the cleaning liquid for aqueous development, water, an alkaline aqueous solution, a neutral detergent, or a surfactant can be used appropriately.

[0240] Examples of the surfactant include anionic surfactants, amphoteric surfactants, nonionic surfactants, etc. These may be used alone or in combination of two or more.

[0241] Examples of the anionic surfactant include, but are not limited to, sulfate ester salts, higher alcohol sulfate ester salts, higher alkyl ether sulfate ester salts, sulfated olefins, alkylbenzene sulfonates, α-olefin sulfonates, phosphate ester salts, and dithiophosphate ester salts.

[0242] The amphoteric surfactant is not particularly limited, and examples thereof include amino acid-based amphoteric surfactants and betaine-based amphoteric surfactants.

[0243] The nonionic surfactant is not limited to the following substances, and examples thereof include polyethylene glycol-type surfactants such as higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher alkylamine ethylene oxide adducts, fatty acid amide ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts; polyhydric alcohol-type surfactants such as glycerol fatty acid esters, pentaerythritol fatty acid esters, fatty acid esters of sorbitol and sorbitan, alkyl esters of polyhydric alcohols, and fatty acid amides of alkanolamines; and the like.

[0244] In addition, the alkaline aqueous solution may contain a pH adjusting agent. As the pH adjusting agent, it may be any of an organic material and an inorganic material, and it is preferably capable of adjusting the pH to above 9. As the pH adjusting agent, it is not limited to the following substances, and for example, sodium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, sodium succinate, etc. may be listed.

[0245] The absorbing layer for thermal development is not particularly limited, and examples thereof include nonwoven fabric materials, paper raw materials, fiber fabrics, open-cell foams, and porous materials. Among them, nonwoven fabric materials formed from nylon, polyester, polypropylene, and polyethylene, and combinations of these nonwoven fabric materials are preferred, and nonwoven continuous webs of nylon or polyester are more preferred.

[0246] 〔Flexographic printing plate〕

[0247] The flexographic printing plate of the present embodiment includes a cured product of the photosensitive resin composition layer produced as described above.

[0248] The flexographic printing plate of the present embodiment comprises a resin having a Shore A hardness of 61 to 77 and satisfying the following equations (4) and (5) when the storage modulus is G' (MPa) and the loss modulus is G" (MPa) in dynamic viscoelasticity measurement at -30°C and 2.5 Hz.

[0249] 1.17≤G'+G”≤1.80 (4)

[0250] 0.17≤G”≤0.30 (5)

[0251] The flexographic printing plate of the present embodiment can achieve excellent abrasion resistance during high-speed printing, and can also achieve reduction and suppression of edge blurring during printing, by having the above-mentioned physical properties throughout the plate.

[0252] From the viewpoint of improving edge whitening and achieving abrasion resistance, the G′+G″ is preferably 1.40 to 1.75, and more preferably 1.50 to 1.70.

[0253] In addition, in the flexible printing original plate of the present embodiment, from the viewpoint of achieving excellent abrasion resistance during high-speed printing, reducing white spots and inhibiting the occurrence of white spots, G" is set to be greater than 0.17 and less than 0.30, preferably greater than 0.17 and less than 0.29, and more preferably greater than 0.17 and less than 0.25.

[0254] Furthermore, the flexographic printing plate of the present embodiment includes a cured product of the photosensitive resin composition having a Shore A hardness of 61 or more and 77 or less, as described above.

[0255] It should be noted that the above hardness refers to the hardness of the entire flexographic printing plate.

[0256] Sufficient printing durability can be obtained by setting the Shore A hardness to 61 or more. In addition, by setting the Shore A hardness to 77 or less, sufficient flexibility can be obtained for the flexographic printing plate, and for example, good workability can be achieved when the flexographic printing plate is wound around a plate body.

[0257] From the viewpoint of achieving both printing durability and flexibility of the flexographic printing plate, the Shore A hardness is 61 or more and 77 or less, preferably 62 or more and 73 or less, and more preferably 63 or more and 70 or less.

[0258] Regarding the cured product of the photosensitive resin composition constituting the flexographic printing plate of the present embodiment, in the dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the ratio of the aforementioned loss modulus G" (MPa) to the aforementioned storage modulus G' (MPa): tanδ = G" / G' is preferably greater than or equal to 0.17 and less than or equal to 0.20, more preferably greater than or equal to 0.17 and less than or equal to 0.19, and further preferably greater than or equal to 0.17 and less than or equal to 0.18.

[0259] The above-mentioned physical property values ​​are physical property values ​​of the entire resin constituting the flexographic printing plate.

[0260] In the above range, even at higher speed printing, the effects of improving edge blurring and suppressing the occurrence of edge blurring are observed.

[0261] 〔Flexible printing method〕

[0262] The flexible printing method of this embodiment uses the above-mentioned flexible printing original plate, and has the following steps: a first step of irradiating ultraviolet rays from the support body (a) side; a second step of irradiating the infrared ablation layer (c) with infrared rays to draw and process a pattern; a third step of irradiating the photosensitive resin composition layer (b) with ultraviolet rays using the infrared ablation layer (c) with the drawn pattern as a mask to perform pattern exposure; a fourth step of removing the unexposed parts of the infrared ablation layer (c) and the photosensitive resin composition layer (b) to manufacture a flexible printing plate; and a fifth step of printing using the flexible printing plate.

[0263] The first step to the fourth step in the flexographic printing method are as described above.

[0264] (Fifth step)

[0265] The fifth step is a step of printing using the flexographic printing plate obtained through the first to fourth steps. The printing method using the flexographic printing plate is not particularly limited as long as the ink is attached to the convex portions of the flexographic printing plate and the ink is transferred to the substrate.

[0266] Example

[0267] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0268] The following methods for measuring physical properties are described for the Examples and Comparative Examples described below.

[0269] [Content ratio of cycloalkane-based hydrocarbon compound contained in photosensitive resin composition relative to the total amount of liquid diene and cycloalkane-based hydrocarbon compound]

[0270] The content of the cycloalkane-based hydrocarbon compound contained in the photosensitive resin composition relative to the total amount of the liquid diene and the cycloalkane-based hydrocarbon compound (hereinafter, this content is referred to as A) is calculated using the following formula (7).

[0271] The number average molecular weight (Mn) of the liquid diene and cycloalkane-based hydrocarbon compounds was measured using the following apparatus and conditions.

[0272] A (mol%) = (mass of added cycloalkane hydrocarbon compound / Mn of cycloalkane hydrocarbon compound) / {(mass of added cycloalkane hydrocarbon compound / Mn of cycloalkane hydrocarbon compound)+(mass of added liquid diene / Mn of liquid diene)}··(7)

[0273] Device: HLC-8220GPC manufactured by Tosoh Corporation

[0274] Column: Four of the following columns were connected in series for separation.

[0275] TSKgel GMH XL manufactured by Tosoh Corporation + TSKgel GMH XL manufactured by Tosoh Corporation + TSKgel GMH XLL manufactured by Tosoh Corporation + TSKgel GMH XLL manufactured by Tosoh Corporation

[0276] Column temperature: 40°C

[0277] Solvent: Tetrahydrofuran

[0278] Detector: RI

[0279] Standard curve: Standard polystyrene

[0280] [Measurement of cycloalkane ratio of cycloalkane-based hydrocarbon compound contained in photosensitive resin composition]

[0281] For cycloparaffinic hydrocarbon compounds, VGC (viscosity specific gravity constant) and r were measured and calculated according to the Kurtz method based on ASTM D2140-08 (2017). i(refractive index), and the percentage of the number of cycloalkane carbon atoms with respect to the total number of carbon atoms derived from these values ​​was defined as the cycloalkane ratio.

[0282] 〔Determination of Shore A Hardness〕

[0283] The photosensitive resin composition was sandwiched between release films (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation), and a pressure of 200 kg / cm was applied at 120° C. for 4 minutes using a 1.5 mm spacer. 2 , thereby obtaining a photosensitive resin composition sheet having a photosensitive resin composition layer (b) having a thickness of 1.5 mm.

[0284] Then, the photosensitive resin composition sheet was exposed to light at 3000 mJ / cm2 from both sides using an ultraviolet fluorescent lamp having a central wavelength of 370 nm in an "AFP-1216" exposure machine (manufactured by Asahi Kasei Corporation). 2 The entire surface was exposed to ultraviolet light to prepare a sample for evaluating Shore A hardness.

[0285] The release film of the obtained sample was peeled off and left in a constant temperature and humidity room at 23°C and 55% relative humidity for one day, and then measured using JIS constant pressure loader GS-710 (manufactured by TECLOCK, hardness tester GS-719G ASTM: D2240A, JIS: K6253A, ISO: 7619A).

[0286] The value after a load (mass 1 kg) was applied to the entire surface for 15 seconds was defined as the Shore A hardness.

[0287] When evaluating the Shore A hardness of the photosensitive resin composition layer (b) based on the flexographic printing plate, the infrared ablation layer (c) constituting the flexographic printing plate is first wiped with a nonwoven fabric using a solvent such as acetone, and then a pressure of 50 kg / cm2 is applied to the laminate of the support (a) and the photosensitive resin composition layer (b) at 120°C for 4 minutes using a press. 2 The photosensitive resin composition layer (b) exposed from the support (a) was recovered by applying a pressure of 200 kg / cm2 at 120°C for 4 minutes using a spacer of 1.5 mm. 2 A photosensitive resin composition sheet having a photosensitive resin composition layer (b) with a thickness of 1.5 mm was obtained. Next, an exposure machine "AFP-1216" was used to expose the photosensitive resin composition sheet from both sides at 3000 mJ / cm 2The entire surface was exposed to ultraviolet light to prepare a sample for evaluating Shore A hardness, and the hardness was measured in the same manner as the above-mentioned measurement method.

[0288] Furthermore, when measuring the Shore A hardness of the flexographic printing plate, the flexographic printing plate was placed in a constant temperature and humidity room at a temperature of 23° C. and a relative humidity of 55% for one day, and then the Shore A hardness of the solid image portion of the flexographic printing plate was measured using the above-mentioned JIS constant pressure loader GS-710.

[0289] In addition, in each Example and Comparative Example, the Shore A hardness measurement was carried out using the sample for evaluation of Shore A hardness produced from the photosensitive resin composition and the flexographic printing plate.

[0290] [Determination of dynamic viscoelasticity]

[0291] The photosensitive resin composition was sandwiched between release films, and a 1.5 mm spacer was used. A pressure of 200 kg / cm was applied at 120° C. for 4 minutes using a press machine. 2 A photosensitive resin composition sheet having a photosensitive resin composition layer (b) with a thickness of 1.5 mm was obtained. Subsequently, an exposure device "AFP-1216" was used to expose the photosensitive resin composition sheet from both sides using 3000 mJ / cm 2 The entire surface was exposed to ultraviolet rays to prepare a sample for dynamic viscoelasticity evaluation.

[0292] The release film of the obtained sample was peeled off, and the cured product with a thickness of 1.5 mm was formed into a circle with a diameter of 8 mm using a punch. The obtained circular sample was set on a parallel plate with a diameter of 8 mm of Discovery Hybrid Rheometer 2 (manufactured by TA Instruments, trademark), and the axial force (normal stress) was set to 5 N, the sensitivity was set to 0.1 N, the strain in the rotation direction was set to 0.1, the measurement temperature was set to -30 ° C, and the measurement frequency was set to the range of 0.1 Hz to 100.0 Hz, and dynamic viscoelasticity measurement, i.e., storage modulus (G'), loss modulus (G") and tanδ (G" / G') were measured.

[0293] When evaluating the dynamic viscoelasticity of the photosensitive resin composition layer (b) based on the flexographic printing plate, first, the infrared ablation layer (c) constituting the flexographic printing plate is wiped with a nonwoven fabric using a solvent such as acetone, and then a pressure of 50 kg / cm2 is applied to the laminate of the support (a) and the photosensitive resin composition layer (b) at 120°C for 4 minutes using a press. 2The photosensitive resin composition layer (b) exposed from the support (a) was recovered by applying a pressure of 200 kg / cm2 at 120°C for 4 minutes using a spacer of 1.5 mm. 2 A photosensitive resin composition sheet having a photosensitive resin composition layer (b) with a thickness of 1.5 mm was obtained. Next, an exposure machine "AFP-1216" was used to expose the photosensitive resin composition sheet from both sides at 3000 mJ / cm 2 The entire surface was exposed to ultraviolet rays to prepare a sample for dynamic viscoelasticity measurement, and viscoelasticity measurement was performed in the same manner as the above-mentioned measurement method.

[0294] In addition, when evaluating the dynamic viscoelasticity of the photosensitive resin composition layer (b) constituting the flexographic printing plate, a portion of the solid image portion of the flexographic printing plate having a thickness of 1.7 mm from the design surface to a depth of 1.5 mm is cut using a cutter or the like, and the resulting photocured product having a thickness of 1.5 mm is formed into a circle having a diameter of 8 mm using a punching punch, and then the dynamic viscoelasticity measurement is performed in the same manner as the above-mentioned measurement method.

[0295] It should be noted that in each embodiment and comparative example, the viscoelasticity of the sample for dynamic viscoelasticity evaluation made of the photosensitive resin composition and the photosensitive resin composition layer (b) constituting the flexographic printing plate was measured. It can be confirmed that the same measurement results can be obtained when the sample made of the photosensitive resin composition is used and when the sample made using the flexographic printing plate is used.

[0296] [Manufacturing example]

[0297] (Production of Laminated Body for Infrared Ablation Layer Formation)

[0298] 100 parts by mass of carbon black (CB) as an infrared absorber, 20 parts by mass of Solsperse 39000 (trade name, manufactured by Lubrizol Japan, with a base value of 30 mgKOH / g) as a dispersant, 80 parts by mass of TUFTEC H1051 (trade name, manufactured by Asahi Kasei Corporation), a hydrogenated product of styrene-butadiene-styrene copolymer elastomer as a binder polymer, and 600 parts by mass of toluene are mixed to obtain an infrared ablation layer coating liquid.

[0299] The infrared ablation layer coating liquid was applied onto a 100 μm thick PET film forming a covering film in such a way 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 the infrared ablation layer and the covering film, i.e., a laminate for forming an infrared ablation layer.

[0300] (Production of Photosensitive Resin Composition)

[0301] <Production of Photosensitive Resin Composition 1>

[0302] 70.0 parts by mass of a styrene-butadiene-styrene copolymer [D-KX405: manufactured by Kraton], 13.0 parts by mass of a liquid polybutadiene [LBR-352: manufactured by Kuraray Co., Ltd.], 10.0 parts by mass of a plasticizer [Regalite R1010: manufactured by Eastman Chemical Co., Ltd.], 7.0 parts by mass of 1,9-nonanediol diacrylate, 3.5 parts by mass of a photopolymerization initiator [2,2-dimethoxy-2-phenylacetophenone: manufactured by BASF], and 0.6 parts by mass of an antioxidant [2,6-di-tert-butyl-p-cresol: manufactured by Sumitomo Chemical Co., Ltd.] were kneaded using a pressure kneader to prepare a photosensitive resin composition 1 (described as resin 1 in Table 1).

[0303] <Production Examples of Photosensitive Resin Compositions 2 to 13>

[0304] Photosensitive resin compositions 2 to 13 (described as resins 2 to 13 in Table 1) were obtained in the same manner as in the photosensitive resin composition 1 except that the composition was changed as shown in Table 1 below.

[0305] The materials in Table 1 are shown below.

[0306] D-KX405: Made by Kraton, styrene-butadiene-styrene copolymer

[0307] D-1102: Made by Kraton, styrene-butadiene-styrene copolymer

[0308] TUFPRENE 315P: Made by Asahi Kasei Corporation, styrene-butadiene-styrene copolymer

[0309] LBR-352: Made by Kuraray, liquid polybutadiene

[0310] Regalite R1010: manufactured by Eastman Chemical Co., Ltd., a cycloparaffinic hydrocarbon compound (cycloparaffin / paraffin ratio = 70 / 30)

[0311] SMOIL P-350: manufactured by Matsumura Oil Co., Ltd., paraffinic hydrocarbon compound (cycloparaffin / paraffin ratio = 30 / 70) [Table 1]

[0312]

[0313] [Example 1]

[0314] <Preparation of Samples for Cold Flow Resistance Evaluation>

[0315] The photosensitive resin composition 1 was sandwiched between release films (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation) and a 3 mm spacer was used. A pressure of 200 kg / cm was applied at 130° C. for 4 minutes using a heating press. 2 After being pressurized, the film was cooled to obtain a photosensitive resin structure having a size of 25 cm long×25 cm wide×3 mm thick.

[0316] <Production of Flexographic Printing Plates>

[0317] A photosensitive resin composition 1 was charged into an extruder, a support (polyethylene terephthalate film) was laminated to one side of the photosensitive resin composition layer extruded from a T-die, and a release film (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation) was laminated to the side of the photosensitive resin composition layer opposite to the support laminated side, to obtain a laminate (thickness: 1.8 mm) of the support and the photosensitive resin composition layer.

[0318] Next, the release film was peeled off, and the infrared ablation layer-forming laminate obtained in the above [Production Example] was laminated so that the infrared ablation layer was in contact with the photosensitive resin composition layer to obtain a flexographic printing plate having a thickness of 1.8 mm.

[0319] Next, exposure was performed using an "AFP-1216" exposure machine from the support (polyethylene terephthalate film) side of the flexographic printing original plate so that the pattern height (RD) after curing would be approximately 0.7 mm.

[0320] Next, the cover film of the infrared ablation layer was peeled off, and the infrared ablation layer was drawn using a laser drawing machine (CDI) manufactured by ESKO. Then, the infrared ablation layer was exposed to 6000 mJ / cm2 of light from the infrared ablation layer side using the aforementioned exposure machine. 2 The image (relief) is exposed.

[0321] Next, SORBIT (a trademark manufactured by MACDERMID, a mixed organic solvent of 60% by mass of hydrocarbons and 40% by mass of aliphatic alcohols, with a boiling point of 155-205°C) was used as a developer, and an "AFP-1321P" developer (a trademark manufactured by Asahi Kasei Corporation) was used to carry out development at a liquid temperature of 30°C and a speed of 135 mm / min, and the film was dried at 60°C for 2 hours.

[0322] Thereafter, as a post-treatment exposure, a sterilizing lamp having a central wavelength of 254 nm was used to expose the entire plate surface at 2000 mJ / cm 2 Then, a UV fluorescent lamp was used to expose 1000 mJ / cm 2 , and a flexible printing plate with a thickness of 1.7 mm was obtained.

[0323] [Examples 2 to 6, Comparative Examples 1 to 7]

[0324] A sample for cold flow resistance evaluation and a flexographic printing plate were obtained in the same manner as in Example 1 except that the photosensitive resin composition used was changed.

[0325] Table 2 shows the photosensitive resin compositions used in Examples 2 to 6 and Comparative Examples 1 to 7, respectively.

[0326] [Evaluation Method]

[0327] <Printing durability during high-speed printing>

[0328] In the printing test with a printing speed of 600 m / min described in the later <High-speed Printing Test>, the image processing analysis device LuzexAP (manufactured by Nireco) was used to measure the 133lpi and 10% dot area ratio of the printing plate before and after printing, and the change rate of the area ratio before and after printing was calculated.

[0329] The evaluation was performed according to the following criteria. The evaluation results are shown in Tables 2 and 3.

[0330] (Evaluation Criteria)

[0331] A: The change in area ratio is 0% or more and less than 5%.

[0332] B: The change in area ratio is 5% or more and less than 6%.

[0333] C: The change in area ratio is 6% or more and less than 7%.

[0334] E: The change in area ratio is 7% or more.

[0335] <Flexibility of the plate>

[0336] The flexographic printing plates obtained in the Examples and Comparative Examples were used and both ends of the flexographic printing plates were bent 100 times in the same direction with a curvature of 150 mmφ so that the support-laminated side of the flexographic printing plates faced inward.

[0337] The state of the bent plate was visually observed from the support-laminated side and evaluated based on the following criteria.

[0338] The evaluation results are shown in Tables 2 and 3.

[0339] (Evaluation Criteria)

[0340] A: No cracks occurred on the plate at all.

[0341] C: Slight cracks occurred on the plate.

[0342] E: Many cracks were generated on the plate.

[0343] <High-speed printing test: the degree of white spots and the ease with which white spots occur>

[0344] Using the flexographic printing plates obtained in [Example] and [Comparative Example], a printing test was carried out using a flexographic printing machine.

[0345] DuploFLEX5.2Plus (manufactured by Lohmann, trademark) was attached as a buffer tape to the support layer side of the flexographic printing plate. XS-716 (manufactured by DIC GRAPHICS, trademark) was used as the aqueous ink. Cardboard paper and an anilox roller with a mesh size of 800 lpi (mesh capacity of 3.8 cm) were used as the printed material. 3 / m 2 ). For three printing speed conditions of 350 m / min, 450 m / min, and 600 m / min, after printing for 10,000 m respectively, the solid part of the printed matter was visually observed.

[0346] Regarding the degree of white blur, if the white blur is minimal and good printing quality is maintained, it is rated as A, and as the degree of white blur worsens, it is rated as B, C, and E.

[0347] In addition, the degree of occurrence of blurring was evaluated based on the following criteria.

[0348] The evaluation results are shown in Tables 2 and 3.

[0349] (Evaluation criteria for the difficulty of occurrence of white spots)

[0350] A: Even at a printing speed of 600 m / min, no white spots on the printed product could be visually confirmed.

[0351] B: When the printing speed is 600 m / min, white spots on the printed material can be visually confirmed for the first time.

[0352] C: From a printing speed of 450 m / min, white spots on the printed matter can be visually confirmed.

[0353] E: From a printing speed of 350 m / min, white spots on the printed material can be visually confirmed.

[0354] <Evaluation of cold flow resistance>

[0355] The samples for cold flow resistance evaluation obtained in the [Example] and [Comparative Example], i.e., the photosensitive resin structures, were cut into 5 cm×5 cm pieces and subjected to a 28 g / cm 2The thickness change after standing at 40°C for 7 days was measured with a load of 100%.

[0356] Evaluation was performed based on the following criteria.

[0357] The evaluation results are shown in Tables 2 and 3.

[0358] (Evaluation Criteria)

[0359] A: The thickness reduction rate is less than 2.0%.

[0360] B: The thickness reduction rate is 2.0% or more and less than 2.5%. C: The thickness reduction rate is 2.5% or more and less than 3.0%.

[0361] [Table 2]

[0362]

[0363] [Table 3]

[0364]

[0365] This application is based on Japanese patent application (Japanese Patent Application No. 2022-081622) filed with the Japan Patent Office on May 18, 2022, the contents of which are incorporated herein by reference.

[0366] Industrial Applicability

[0367] The flexographic printing original plate of the present invention has industrial applicability in the field of flexographic printing plate production.

[0368] Description of Reference Numerals

[0369] (a) Support body

[0370] (b) Photosensitive resin composition layer

[0371] (b') Printing pattern

[0372] (c) Infrared ablation layer

[0373] (c') Mask of infrared ablation layer

Claims

1. A flexographic printing plate, comprising at least a support (a) and a photosensitive resin composition layer (b) laminated together, The photosensitive resin composition layer (b) contains a cycloalkane hydrocarbon compound having a cycloalkane ratio of 60% or more and 80% or less, and satisfies the following <Condition 1>, <Condition 1> The photosensitive resin composition constituting the photosensitive resin composition layer (b) is molded into a 1.5 mm thick layer and irradiated with ultraviolet rays of 3000 mJ from the upper surface and the lower surface respectively, and the Shore A hardness of the cured product obtained is 60 or more and 75 or less, In a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the storage modulus G' (MPa) and the loss modulus G" (MPa) of the cured product satisfy the following equations (1) and (2): 1.04≤G'+G”≤1.79 (1) 0.15≤G”≤0.30 (2)。 2. The flexographic printing plate according to claim 1, wherein In a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the ratio of the loss modulus G" (MPa) to the storage modulus G' (MPa) of the cured product, tanδ = G" / G', satisfies the following formula (3): 0.17≤tanδ≤0.20 (3).

3. The flexographic printing original plate according to claim 1 or 2, wherein: The cycloalkane ratio of the cycloalkane-based hydrocarbon compound is 65% or more and 73% or less.

4. The flexographic printing original plate according to claim 1 or 2, wherein: The content of the cycloalkane-based hydrocarbon compound in the photosensitive resin composition layer (b) is 3% by mass or more and 20% by mass or less.

5. The flexographic printing original plate according to claim 1 or 2, wherein: The photosensitive resin composition layer (b) further comprises a liquid conjugated diene, The content of the cycloalkane-based hydrocarbon compound is 91 mol% or more and 99 mol% or less relative to the total amount of the liquid conjugated diene and the cycloalkane-based hydrocarbon compound.

6. A method for producing a flexographic printing plate, which is a method for producing a flexographic printing plate using the flexographic printing original plate according to claim 1 or 2, comprising the following steps: A first step of irradiating ultraviolet light from the support (a) side; The second step is to place a negative film on the photosensitive resin composition layer (b), or to laser ablate the infrared ablation layer (c) provided on the photosensitive resin composition layer (b) to produce a negative pattern; The third step is to irradiate the photosensitive resin composition layer (b) with ultraviolet light through the negative film or the infrared ablation layer (c) having the pattern as a mask to perform pattern exposure; as well as The fourth step is to remove the unexposed portion of the photosensitive resin composition layer (b).

7. A flexographic printing plate comprising a cured product of a photosensitive resin composition, The Shore A hardness of the cured product is 61 or more and 77 or less, and in a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the storage modulus G' (MPa) and the loss modulus G" (MPa) of the cured product satisfy the following formulas (4) and (5), 1.17≤G'+G”≤1.80 (4) 0.17≤G”≤0.30 (5)。 8. The flexographic printing plate according to claim 7, wherein In a dynamic viscoelasticity measurement at -30°C and 2.5 Hz, the ratio of the loss modulus G" (MPa) to the storage modulus G' (MPa) of the cured product of the photosensitive resin composition, tanδ = G" / G', further satisfies the following formula (6), 0.17≤tanδ≤0.20 (6).

9. A flexible printing method comprising the following steps: An ink attaching step of attaching ink to convex portions of the flexographic printing plate using the flexographic printing plate according to claim 7 or 8; and A transfer step of transferring the ink to a substrate.

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