JP2020013066A - Photosensitive ctp flexographic printing plate precursor - Google Patents

Abstract

To provide a photosensitive CTP flexographic printing plate precursor having a high-performance barrier layer preventing generation of wrinkles in a low-temperature low-humidity environment as well as giving a flat top shape without thickening in highlight dots obtained from the printing plate precursor.SOLUTION: The photosensitive CTP flexographic printing plate precursor comprises at least (A) a support body, (B) a photosensitive resin layer, and (C) a thermosensitive mask layer, successively stacked, and can be developed with water, in which (D) a barrier layer made of a polyamide resin containing a polyether derived from a polyethylene glycol or a polyethylene glycol copolymer by 15 to 35 mass% in the molecule is disposed between the (C) thermosensitive mask layer and the (B) photosensitive resin layer.SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive CTP flexographic printing plate precursor used for producing letterpress printing plates by computer plate making technology, and in particular, has no wrinkling during low-temperature and low-humidity work, and has excellent halftone dot reproducibility of the obtained printing plate. Flexographic printing original plate.

  In recent years, in the field of flexographic printing, computer plate making technology (CTP technology), which is known as digital image forming technology, has become extremely popular. The CTP technique is a method of directly outputting information processed on a computer onto a printing original to obtain a relief pattern serving as a relief. This technique eliminates the need for a negative film manufacturing process, thereby reducing costs and the time required to make the negative.

  In CTP technology, the traditionally used negative film is replaced by a mask that is formed and integrated in the printing plate to cover areas that should not be photopolymerized. As a method of obtaining the integrated mask, a method of forming an image mask by providing an infrared-sensitive layer (thermosensitive mask layer) opaque to actinic radiation on a photosensitive resin layer and evaporating the infrared-sensitive layer with an infrared laser. Is widely used (see Patent Document 1).

  As the heat-sensitive mask layer, a material composed of carbon black as a radiation opaque material and a binder is generally used. The heat-sensitive mask layer is ablated by an infrared laser, and a thinner layer is preferable in terms of ablation efficiency. Also, the thinner the film, the less the effect of wrinkles on the relief. However, the heat-sensitive mask layer is generally required to have a transmission optical density (light-shielding property) of 2.0 or more in order to prevent transmission of radiation to the photopolymerization layer.

  The photosensitive flexographic CTP printing original plate of Patent Document 1 includes a photosensitive resin layer, a protective layer, and an infrared-sensitive layer, and the protective layer is also called a barrier layer. The barrier layer disposed between the photosensitive resin layer and the infrared-sensitive layer functions to prevent mass transfer between the photosensitive resin layer and the infrared-sensitive layer and to prevent polymerization of the photosensitive resin layer by oxygen in the atmosphere. It has a function to prevent and plays an important role.

  However, when these water-developable photosensitive resin layers are used as the photosensitive resin layer of the CTP plate, there is a problem that wrinkles are generated on the plate surface because the flexibility of the photosensitive resin is high. The wrinkles are generated when the plate is removed from the drum and returned to a flat surface after the plate is attached to the drum during laser processing. The above problem is particularly remarkable when a photosensitive resin layer containing latex as a main component is used. This is presumably because the latex exists in the form of fine particles and the plate is more flexible.

  To solve the problem of wrinkles, Patent Document 2 discloses that the protective layer is made flexible by blending a large amount of a specific plasticizer with polyvinyl alcohol, which is a binder polymer of the protective layer (barrier layer), to reduce wrinkles. It has been proposed to reduce it. Patent Document 3 proposes that the generation of wrinkles is reduced by appropriately controlling the Young's modulus and the layer thickness of the protective layer.

  In recent years, photosensitive CTP flexographic printing original plates are becoming the main platemaking technology in place of analog plates using negative films. As a result, the CTP printing original plate was operated under a wide range of environmental conditions from a high temperature and high humidity environment to a low temperature and low humidity environment. As a result, the barrier layer of the CTP printing original plate wrinkled under low-humidity environmental conditions, and was particularly likely to wrinkle under low-temperature and low-humidity environments. However, the printing original plates of Patent Documents 2 and 3 cannot effectively prevent the generation of wrinkles in a low-temperature and low-humidity environment. Therefore, a photosensitive CTP flexographic printing plate having a high-performance barrier layer that can prevent wrinkles from occurring under low-temperature and low-humidity environmental conditions and obtain a flat top shape without thickening highlight dots is obtained. It is strongly desired.

Japanese Patent Publication No. Hei 7-506201 Patent No. 5573675 Patent No. 4332865

  The present invention has been made in view of the above-mentioned state of the art, and has as its object the purpose of preventing the generation of wrinkles during handling of a CTP printing original plate due to environmental changes for one year, and having excellent barrier properties. An object of the present invention is to provide a photosensitive CTP flexographic printing plate precursor. In particular, it is an object of the present invention to provide a photosensitive flexographic printing plate precursor free from wrinkles even in a low-temperature and low-humidity environment.

  The present inventors have conducted intensive studies in order to achieve the above object, and as a result, it has been found that, between (C) the heat-sensitive mask layer and (B) the photosensitive resin layer, polyethylene glycol or a polyethylene glycol copolymer is present in the molecule. By providing a (D) barrier layer comprising a polyamide resin containing 15 to 35% by mass of a polyether to be formed, it is possible to effectively prevent wrinkles from occurring in a low-temperature and low-humidity environment while maintaining barrier properties. The present invention has been completed.

That is, the present invention has the following configurations (1) to (4).
(1) A photosensitive CTP flexographic printing original plate comprising at least (A) a support, (B) a photosensitive resin layer, and (C) a heat-sensitive mask layer sequentially laminated, wherein (C) a heat-sensitive mask layer and (B) (D) a barrier layer comprising a polyamide resin containing 15 to 35% by mass of a polyether derived from polyethylene glycol or a polyethylene glycol copolymer in a molecule between the photosensitive resin layer and the photosensitive layer; Photosensitive CTP flexographic printing original plate.
(2) The water according to (1), wherein the polyether contained in the polyamide resin in the (D) barrier layer in the molecule is a polyetheramide or a polyetheresteramide having a number average molecular weight of 400 to 1,000. Developable photosensitive CTP flexographic printing plate.
(3) The water-developable photosensitive CTP flexographic printing according to (1) or (2), wherein the polyamide resin in the (D) barrier layer is a polyamide containing a piperazine ring in a molecule. Original version.
(4) The photosensitive resin composition used for the photosensitive resin layer (B) contains a polymer obtained from an aqueous dispersion latex as a synthetic polymer compound, according to any one of claims 1 to 3. Photosensitive relief printing original plate.

  According to the present invention, it is possible to provide a photosensitive CTP flexographic printing original plate which does not generate wrinkles during handling of the CTP printing original plate in a low-temperature and low-humidity environment and has excellent barrier properties.

  Hereinafter, the flexographic printing original plate of the present invention will be described in detail.

  The flexographic printing original plate of the present invention comprises at least (A) a support, (B) a photosensitive resin layer, (C) a heat-sensitive mask layer, and (C) a heat-sensitive mask layer between the (C) heat-sensitive mask layer and the (B) photosensitive resin layer. And) a basic structure in which barrier layers are sequentially stacked.

  The support used for the flexographic printing plate precursor of the present invention is flexible, but a material excellent in dimensional stability is preferable, for example, steel, aluminum, copper, a metal support such as nickel, a polyethylene terephthalate film, A support made of a thermoplastic resin such as a polyethylene naphthalate film, a polybutylene terephthalate film, or a polycarbonate film can be used. Among these, a polyethylene terephthalate film having excellent dimensional stability and sufficiently high viscoelasticity is particularly preferred. The thickness of the support is preferably from 50 to 350 μm, and more preferably from 100 to 250 μm, from the viewpoint of mechanical properties, shape stabilization, and handling during printing plate making. If necessary, an adhesive may be provided between the support and the photosensitive resin layer in order to improve the adhesion between the support and the photosensitive resin layer.

  The photosensitive resin layer used in the flexographic printing plate precursor of the present invention is a synthetic polymer compound, a photopolymerizable unsaturated compound, and essential components of a photopolymerization initiator, a plasticizer, a thermal polymerization inhibitor, a dye, a pigment, It contains an optional additive such as a UV absorber, a fragrance, or an antioxidant.

  The barrier layer used in the flexographic printing plate precursor of the present invention exhibits its effect when the photosensitive resin layer that has not been photocured has high flexibility. Flexibility can be evaluated by the amount of indentation displacement. According to the present invention, wrinkles can be reduced even when the amount of indentation of the photosensitive resin layer is 5 μm or more. Examples of the highly flexible photosensitive resin layer include a photosensitive resin layer containing a water-dispersible polymer obtained from latex as a polymer compound.

  Latexes capable of obtaining a water-dispersible polymer include polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, and methyl latex. Water-dispersed latex polymers such as methacrylate-butadiene copolymer latex, vinylpyridine polymer latex, butyl polymer latex, thiochol polymer latex, acrylate polymer latex, and other polymers such as acrylic acid and methacrylic acid. And a polymer obtained by copolymerizing the above components. Among them, a water-dispersed latex polymer containing a butadiene skeleton or an isoprene skeleton in a molecular chain is preferably used from the viewpoint of hardness and rubber elasticity. Specifically, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, and polyisoprene latex are preferred. The polymer obtained from the latex is preferably present as independent fine particles in the photopolymerizable unsaturated compound.

  The photosensitive resin layer used in the flexographic printing plate precursor according to the invention may contain a synthetic rubber solid at room temperature as long as the water developability is not reduced as a synthetic polymer compound. Specific synthetic rubber is a synthetic rubber selected from butadiene rubber, nitrile-butadiene rubber, isoprene rubber, styrene-isoprene rubber, and styrene-butadiene rubber. These may be used alone or in combination of two or more. Of these, butadiene rubber and nitrile-butadiene rubber are preferred, and butadiene rubber is most preferred. Further, it is preferable that the hydrophobic polymer and the rubber obtained from the aqueous dispersion latex of the conjugated diene rubber component have a common skeleton structure. Thereby, the mechanical strength of the photosensitive resin layer is improved, and a printing plate having printing durability can be obtained. In order to improve the mechanical strength of the photosensitive resin layer, the synthetic rubber to be compounded is a solid high-molecular polymer, and does not include a liquid rubber or a low-molecular-weight oligomer. The compounding amount of the conjugated diene-based rubber component in the photosensitive resin composition constituting the photosensitive resin layer is preferably 1 to 40% by mass, more preferably 1 to 20% by mass. In particular, in order to reduce the influence of water developability, the content is preferably 1 to 10% by mass.

  A plasticizer can be added to the photosensitive resin composition for the purpose of imparting flexibility. The blending amount of the plasticizer is preferably 0.1 to 30% by mass. More preferably, it is 5 to 20% by mass. If the amount is less than the lower limit, the effect of imparting flexibility to the photosensitive resin composition may be reduced. If the upper limit is exceeded, a problem may occur in the strength of the photosensitive resin composition.

  The plasticizer is not particularly limited as long as it generally has a property of softening the plate material, but a plasticizer having good compatibility with other components is preferable. Specifically, a polyene compound which is liquid at room temperature or a compound having an ester bond can be used. Examples of the polyene compound which is liquid at room temperature include liquid polybutadiene, polyisoprene, and a maleated or epoxidized compound having modified terminal groups or side chains thereof. Examples of the compound having an ester bond include a phthalate, a phosphate, a sebacate, an adipate, and a polyester having a molecular weight of 1,000 to 3,000.

  The photosensitive CTP flexographic printing plate precursor of the present invention comprises, between (C) the heat-sensitive mask layer and (B) the photosensitive resin layer, 15 to 35 polyethers derived from polyethylene glycol or a polyethylene glycol copolymer in the molecule. The most characteristic feature is that a barrier layer (D) made of a polyamide resin containing by mass% is provided. By providing the (D) barrier layer containing such a specific polyamide resin, excellent image reproducibility without being affected by polymerization by oxygen, and wrinkles are generated even when handling the CTP master at a low temperature. And a flexo CTP master plate having a high performance without any problem.

  (D) The polyamide resin used for the barrier layer is a polyamide resin containing 15 to 35% by mass of a polyether derived from polyethylene glycol or a polyethylene glycol copolymer in the molecule. As the polyether, polyethylene glycol is preferable, but a polyethylene glycol copolymer obtained by copolymerizing an alkylene glycol other than polyethylene glycol may be used as long as the water solubility and physical properties are not reduced. Examples of the alkylene glycol other than polyethylene glycol include polypropylene glycol and polytetramethylene glycol. The copolymerization ratio is preferably less than 50% by mass, more preferably less than 35% by mass, from the influence on water solubility and physical properties. As the method of copolymerization, random copolymerization or block copolymerization may be used, but block copolymerization is preferred from the viewpoint of physical properties.

(D) The number average molecular weight of the polyether contained in the molecule of the polyamide resin used for the barrier layer is preferably from 400 to 1,000, more preferably from 400 to 800, from the viewpoint of the physical properties of the barrier layer and the glass transition point. Further, in order to improve the water solubility, the polyamide resin (B) may contain a basic nitrogen atom in the molecule. Further, when the content of the polyether contained in the molecule of the polyamide resin used in the barrier layer (D) is less than the above lower limit, the amount of the polyether bond becomes too small, so that wrinkling at the time of low-temperature operation is prevented. It cannot be prevented, and the coatability of the barrier layer may be poor. On the other hand, when the content of the alkylene glycol structural unit exceeds the above upper limit, oxygen barrier properties of the barrier layer may be insufficient, and edge reproducibility of the relief dot top may be poor.

(D) The polyamide resin used for the barrier layer may contain a basic nitrogen atom. It is preferable to include a basic nitrogen atom since the solubility in water can be improved. The basic nitrogen atom is a nitrogen atom constituting an amino group that is not an amide group. As such a polyamide resin, a polyamide resin having a basic nitrogen atom in the main chain is preferable. Polyamide resin containing a basic nitrogen atom, for example, as a diamine containing a basic nitrogen atom, copolymerized using a diamine containing a basic nitrogen atom such as a diamine having a piperazine ring or methyliminobispropylamine as a diamine component It is obtained by doing. (D) As the polyamide resin used for the barrier layer, it is particularly preferable to use a diamine having a piperazine ring from the viewpoint of water solubility. Examples of the diamine having a piperazine ring include 1,4-bis (3-aminoethyl) piperazine, 1,4-bis (3-aminopropyl) piperazine, and N- (2-aminoethyl) piperazine. Further, (D) the polyamide resin used for the barrier layer may be copolymerized using a raw material such as a diamine, dicarboxylic acid or aminocarboxylic acid which does not partially contain a basic nitrogen atom from the viewpoint of physical properties. A method for obtaining a polyamide resin containing a basic nitrogen atom in the molecule is disclosed in, for example, JP-A-50-7605.

  The amount of basic nitrogen atoms contained in the polyamide molecule is preferably from 0.3 mol to 2.0 mol per 1000 g of the polyamide resin. If it is less than 0.3 mol, the effect of improving the water solubility is small, and if it exceeds 2.0 mol, it is liable to be affected by the humidity of the working environment.

  (D) The polyamide resin used for the barrier layer is preferably copolymerized with 6-nylon or 66-nylon in the polyamide in order to improve the properties of the polyamide resin, and preferably contains 45 to 75% by mass. If it is less than 45% by mass, there is no effect of improving the physical properties, and if it exceeds 75% by mass, the water solubility or water dispersibility decreases, which is not preferable.

  (D) Polyether amide or polyether ester amide can be used as the polyamide resin used for the barrier layer, but polyether amide is preferable from the viewpoint of hydrolysis resistance. Polyetheramide can be synthesized according to JP-A-55-79437. Specifically, polyetheramide can be synthesized by adding acrylonitrile to both ends of polyethylene glycol and reducing it with hydrogen to use α, ω-diaminopolyoxyethylene as a diamine component. On the other hand, polyetheresteramide can be synthesized by a general method using polyethyleneglycol as a raw material and introducing polyethyleneglycol into the molecule through an ester bond.

  In the present invention, the (D) barrier layer composed of a polyamide resin containing 15 to 35% by mass of a polyether in a molecule has a water-soluble or water-dispersible property, and has an appropriate thickness that does not cause a fattening in an image of a printing plate obtained. It has a role of providing oxygen barrier properties. Further, (D) the barrier layer contains a polyether in the molecule, thereby having a role of preventing wrinkles from occurring during handling of the CTP printing original plate. In particular, it has become possible to prevent wrinkles even during low-temperature work.

  Whether the polyamide of the present invention is water-soluble or water-dispersible can be determined by immersing the sheet-shaped polyamide alone in 30 ° C. water or acidic water and rubbing it with a brush or the like. If the polyamide is uniformly mixed with water or acidic water after being physically rubbed with a brush or the like, the polyamide is determined to be water-soluble. On the other hand, after physically rubbing with a brush or the like, part or all of the polyamide swells and disperses in water, and when the polyamide is mixed unevenly, the polyamide is determined to be water dispersible. .

  The barrier layer may contain additives as long as the performance is not adversely affected. Examples of the additive include a plasticizer and various stabilizers. In particular, when it is desired to improve the water developability of the barrier layer, it is preferable to incorporate a hydrophilic plasticizer or a surfactant into the barrier layer. Further, in order to reduce the defects of the barrier layer, additives such as an antifoaming agent and a leveling agent may be blended as long as the performance is not adversely affected.

Examples of the hydrophilic plasticizer and surfactant for improving the water solubility of the polyamide include the following compounds. The hydrophilic plasticizer has good compatibility with the polyamide used for the barrier layer, and includes, for example, glycol compounds such as ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. The glycol compound may be a modified glycol compound. Examples of the surfactant include a nonionic surfactant, a cationic surfactant, and an anionic surfactant. The amount used is usually 5% by mass or less based on the mass of the barrier layer.

  Generally, it has been considered that the barrier layer has two functions. One is an "interlayer barrier property" that prevents a substance from moving between an adjacent photosensitive resin layer or a heat-sensitive mask layer. The other is "oxygen barrier property" that prevents polymerization inhibition when irradiating the entire surface with actinic rays toward the photosensitive resin layer via a mask. If there is a problem in the "oxygen barrier property", it causes troubles such as the inability to obtain fine halftone dots in the produced photosensitive printing original plate or the rounded shape of the end of the fine halftone dots. Therefore, it is important whether the halftone dot diameter can be obtained according to a predetermined size.

  The heat-sensitive mask layer used in the flexographic printing plate precursor of the present invention is a material having a function of absorbing infrared laser to convert it into heat and a function of blocking ultraviolet light, a carbon black, and a binder for dispersing the same. And a binder polymer. The dispersing binder and the binder polymer capable of forming a film can be used in combination. In addition, as an optional component other than these, a pigment dispersant, a filler, a surfactant, a coating aid, and the like can be contained as long as the effects of the present invention are not impaired.

  The heat-sensitive mask layer used in the flexographic printing plate precursor according to the invention is not particularly limited, but is preferably water-developable. Specific examples of the heat-sensitive mask layer include a heat-sensitive mask layer obtained by combining a polar group-containing polyamide and a butyral resin (Japanese Patent No. 4200510), a polymer having the same structure as the polymer in the photosensitive resin layer, and an acrylic resin. A heat-sensitive mask layer (Japanese Patent No. 5710961); and a heat-sensitive mask layer containing an anionic polymer and a polymer having an ester bond in a side chain and having a saponification degree of 0% or more and 90% or less (Japanese Patent No. 5525074). .

The method for producing the flexographic printing plate precursor of the present invention is not particularly limited, but is generally produced as follows.
First, a component such as a binder other than carbon black of the heat-sensitive mask layer is dissolved in an appropriate solvent, and carbon black is dispersed therein to prepare a dispersion. Next, such a dispersion is applied onto a support for a heat-sensitive mask layer (for example, a polyethylene terephthalate film), and the solvent is evaporated. Thereafter, a barrier layer component is overcoated to form one of the laminates. Further, separately from this, a photosensitive resin layer is formed on the support by coating, and the other laminate is formed. The two laminates thus obtained are laminated under pressure and / or heat so that the photosensitive resin layer is adjacent to the barrier layer. The support for the heat-sensitive mask layer functions as a protective film on the surface of the printing plate after completion of the printing plate.

  As a method for producing a printing plate from the CTP printing original plate of the present invention, if a protective film is present, the protective film is first removed from the photosensitive printing plate. Thereafter, the thermal mask layer is irradiated imagewise with an IR laser to form a mask on the photosensitive resin layer. Examples of suitable IR lasers include an ND / YAG laser (1064 nm) or a diode laser (eg, 830 nm). Laser systems suitable for computer platemaking technology are commercially available, for example, CDI Spark (Esco Graphics) can be used. This laser system includes a rotating cylindrical drum for holding a printing plate, an irradiation device of an IR laser, and a layout computer, and image information is directly transferred from the layout computer to the laser device.

  After the image information is written on the heat-sensitive mask layer, the photosensitive printing plate precursor is irradiated with actinic rays through the mask. This can be done with the plate attached to the laser cylinder, but removing the plate from the laser and irradiating it with a conventional flat irradiation unit is advantageous in that it can accommodate non-standard plate sizes. And general. Ultraviolet rays having a wavelength of 150 to 500 nm, particularly 300 to 400 nm can be used as the actinic ray. As the light source, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a zirconium lamp, a carbon arc lamp, a fluorescent lamp for ultraviolet rays and the like can be used. Thereafter, the irradiated plate is developed to obtain a printing plate. The developing step can be performed by a conventional developing unit.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. The number of parts in the examples (the text) indicates parts by mass.

  Hereinafter, the materials used in each example will be described.

<Synthesis of polyamide resin>
PEA-1: 744 parts by mass of ε-caprolactam, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction of the same to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid 264 parts by mass of the salt and 1000 parts by mass of water were charged in an autoclave and melt-polymerized under ordinary conditions. The obtained polyamide was a polyetheramide having a glass transition point of 46 ° C., containing 18% by mass of a polyethylene glycol structural unit in the molecule.
PEA-2: 671 parts by mass of ε-caprolactam, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction of the same to obtain equimolar amounts of α, ω-diaminopolyoxyethylene and adipic acid 329 parts by mass of the salt and 1000 parts by mass of water were charged in an autoclave and melt-polymerized under ordinary conditions. The obtained polyamide was a polyetheramide having a glass transition point of 46 ° C., containing 23% by mass of a polyethylene glycol structural unit in the molecule.
PEA-3: 545 parts by mass of ε-caprolactam, acrylonitrile added to both terminals of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction of the same to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid 455 parts by mass of the salt and 1000 parts by mass of water were charged into an autoclave and melt-polymerized under ordinary conditions. The obtained polyamide was a polyether amide having a glass transition point of 46 ° C. containing 31% by mass of a polyethylene glycol structural unit in the molecule.
PEA-4: 516 parts by mass of ε-caprolactam, 163 parts by mass of 1,4-bis (3-aminopropyl) piperazine adipate, acrylonitrile is added to both ends of polyethylene glycol having a number average molecular weight of 600, and this is hydrogen reduced. 321 parts by weight of the obtained equimolar salt of α, ω-diaminopolyoxyethylene and adipic acid and 1000 parts by weight of water were melt-polymerized under ordinary conditions. The obtained polyamide was a polyetheramide containing 23% by mass of a polyethylene glycol structural unit in the molecule and 1.0 mol of a tertiary nitrogen atom per 1000 parts by mass.
PEA-5: 541 parts by mass of ε-caprolactam, 136 parts by mass of N- (2-aminoethyl) piperazine and a nylon salt of adipic acid, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction. Then, 323 parts by mass of an equimolar salt of α, ω-diaminopolyoxyethylene and adipic acid and 1,000 parts by mass of water were melt-polymerized under ordinary conditions. The obtained polyamide was a polyetheramide containing 23% by mass of a polyethylene glycol structural unit in the molecule and 1.0 mol of a tertiary nitrogen atom per 1000 parts by mass. The tertiary nitrogen amount is the tertiary nitrogen amount in the piperazine ring, and contains two moles of tertiary nitrogen atoms per mole of piperazine.
PEA-6: 489 parts by mass of ε-caprolactam, acrylonitrile is added to both ends of polyethylene glycol having a number average molecular weight of 400, and hydrogen reduction is performed to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid. 511 parts by mass of the salt and 1000 parts by mass of water were melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 33% by mass of a polyethylene glycol structural unit in the molecule.
PEA-7: 589 parts by mass of ε-caprolactam, acrylonitrile is added to both ends of polyethylene glycol having a number average molecular weight of 800, and hydrogen reduction is performed to obtain equimolar amounts of α, ω-diaminopolyoxyethylene and adipic acid. 411 parts by mass of the salt were melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 31% by mass of a polyethylene glycol structural unit in the molecule.
PEA-8: 602 parts by mass of ε-caprolactam, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 1,000, and hydrogen reduction of the same to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid 398 parts by mass of the salt were melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 32% by mass of a polyethylene glycol structural unit in the molecule.
PEA-9: 862 parts by mass of ε-caprolactam, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction of the same to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid 138 parts by mass of the salt was melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 9% by mass of a polyethylene glycol structural unit in the molecule.
PEA-10: 409 parts by mass of ε-caprolactam, acrylonitrile is added to both terminals of polyethylene glycol having a number average molecular weight of 600, and hydrogen reduction is performed to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid. 591 parts by mass of the salt was melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 43% by mass of a polyethylene glycol structural unit in the molecule.
PEA-11: 449 parts by mass of ε-caprolactam, acrylonitrile was added to both ends of polyethylene glycol having a number average molecular weight of 200, and hydrogen reduction was performed to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid. 551 parts by mass of the salt was melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 33% by mass of a polyethylene glycol structural unit in the molecule.
PEA-12: 568 parts by mass of ε-caprolactam, acrylonitrile added to both ends of polyethylene glycol having a number average molecular weight of 1200, and hydrogen reduction of the same to obtain an equimolar amount of α, ω-diaminopolyoxyethylene and adipic acid 432 parts by mass of the salt was melt-polymerized under ordinary conditions. The resulting polyamide was a polyetheramide containing 33% by mass of a polyethylene glycol structural unit in the molecule.
PEEA: A polyetheresteramide comprising the following components was synthesized based on a known formulation (for example, JP-A-58-11737). 260 parts by mass of ε-caprolactam, 319 parts by mass of a salt of hexamethylenediamine and adipic acid, 420 parts by mass of polyethylene glycol having a number average molecular weight of 600 and an equimolar amount of adipic acid at 250 ° C. under reduced pressure in the presence of a tetrabutyl titanate catalyst. The reaction was carried out for a long time to obtain a polyetheresteramide. The resulting amide was a polyetherester containing 33% by mass of an alkylene glycol structural unit in the molecule.

<Preparation of coating composition for barrier layer>
The polyamide resin synthesized in Table 1 was dissolved in ethanol at 60 ° C. so as to have a solid content of 10% by mass to prepare a barrier layer coating liquid.

<Create thermal mask layer>
As a coating liquid for the heat-sensitive mask layer, a mixture of a carbon black dispersion (AMBK-8, manufactured by Orient Chemical Industries, Ltd.) and a copolymerized polyamide of PA-1 was used. The mixing ratio of each component in the mixture was as follows: carbon black: butyral resin: copolyamide = 35: 28: 37 in terms of solid mass ratio. Then, after both sides of a PET film (Toyobo Co., Ltd., E5000, thickness: 100 μm) were subjected to a release treatment, a heat-sensitive mask layer coating solution was applied using a bar coater # 12, and 120 ° C. × 5. And dried. The optical density at this time was 2.3. The optical density was measured by a black and white transmission densitometer DM-520 (Dainippon Screen Manufacturing Co., Ltd.).

<Preparation of heat-sensitive mask layer laminate film with barrier layer>
On the created heat-sensitive mask layer, a coating solution for a barrier layer is applied using a suitable type of bar coater so as to have a predetermined thickness, and dried at 120 ° C. for 5 minutes to make the barrier layer the uppermost layer. A film of the provided heat-sensitive mask layer laminate was obtained.

<Preparation of photosensitive resin composition for photosensitive resin layer>
Acrylonitrile-butadiene latex (Nipol SX1503, nonvolatile content 42%, manufactured by Nippon Zeon Co., Ltd.) 10 parts by mass, butadiene latex (Nipol LX111NF, nonvolatile content 55%, manufactured by Nippon Zeon Co., Ltd.) 58 parts by mass, oligobutadiene acrylate (ABU-2S Kyoeisha) 28 parts by mass of Chemical Co., Ltd., 4 parts by mass of lauryl methacrylate (Light Ester L manufactured by Kyoeisha Chemical Co., Ltd.), 4 parts by mass of dimethylol tricyclodecane diacrylate, 1 part by mass of benzyldimethyl ketal as a photopolymerization initiator, 0.1 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor and 0.1 parts by mass of a nonionic surfactant as other additives are mixed together with 15 parts by mass of toluene in a vessel, and then 105 ° C. using a pressure kneader. And then knead And the water to be removed under reduced pressure to obtain a photosensitive resin composition used in the photosensitive resin layer. The indentation displacement of this composition was measured and found to be 15 μm.

<Print master plate creation>
The above photosensitive resin composition was disposed on a PET film support (Toyobo Co., Ltd., E5000, thickness 125 μm) coated with a copolymerized polyester adhesive, and a barrier layer was provided on the uppermost layer from above. The films of the heat-sensitive mask layer laminate were overlaid. Lamination was performed at 100 ° C. using a heat press machine to obtain an original flexographic printing plate comprising a PET support, an adhesive layer, a photosensitive resin layer, a protective layer, a heat-sensitive mask layer, and a release-treated PET protective film (cover film). The total thickness of the plate was 1.90 mm.

<Creating a printing plate from a printing plate>
Ultraviolet rays (light source: Philips 10R, illuminance at 365 nm: 8 mW / cm ² ) were irradiated from the PET support side of the original for 1 minute. Subsequently, the release-treated PET film (cover film) was peeled off. This plate was wound around a rotating drum of Digital Imager Spark (manufactured by Barco) so that the heat-sensitive mask layer was on the front side, and after evacuation, an image was formed. After the ablation, the plate was taken out, returned to a flat surface, and irradiated with actinic radiation (illuminance of 8 mW / cm ^{2 at} Philips 10R, 365 nm) for 6 minutes. Thereafter, development was performed at 40 ° C. for 8 minutes using a developing machine (Stuck System) manufactured by A & V Corporation. Tap water to which 1% of dishwashing detergent Cascade (manufactured by P & G, USA) was added was used as the developing solution. After development, the film was dried at 60 ° C. for 10 minutes, irradiated with actinic radiation for 10 minutes, and finally irradiated with a germicidal lamp for 5 minutes to remove surface stickiness.

<Evaluation method>
Wrinkle resistance: The prepared flexographic printing plate precursor was cut into a width of 20 cm and a length of 20 cm to obtain an evaluation sample. The sample was stored on a flat table for 24 hours in a thermostatic chamber at 10 ° C. or 30 ° C. under a condition of a relative humidity of 25% to prepare the sample. Thereafter, the cover sheet of the sample was peeled off, wrapped around a cylindrical roll (200 mm in diameter) so that the barrier layer was on the outside, fixed for 5 minutes, and then removed and allowed to stand on a flat place for 5 minutes. After that, the surface of the barrier layer was visually observed, and judged based on the following criteria.

：: No wrinkles were found on the barrier layer. △: Wrinkles were found on a part of the barrier layer. X: Wrinkles were found on the entire surface of the barrier layer.

Coating property of barrier layer: The barrier layer of the present invention was hand-coated on an A4 size PET film using a bar coater. After the sample was hand-coated at room temperature, it was placed in a hot air dryer set at 100 ° C. and allowed to stand for 10 minutes. Thereafter, a sample was taken out from the hot air drier, and the surface of the barrier layer was visually observed, and judged according to the following criteria.

：: The barrier layer has a smooth coat surface and the coat layer is not turbid. △: The barrier layer has a smooth coat surface but the coat layer has turbidity. X: The barrier layer coat surface is like a streak or cissing. Defects confirmed

Water developability: The prepared flexographic printing plate precursor was immersed in a developer and rubbed with a brush dedicated to a developing machine using nylon fibers having a diameter of 100 μm and 160 μm at 40 ° C. for 5 minutes. The judgment was made based on the standard.

◎: The barrier layer can be developed with water by rubbing for 60 seconds ：: The barrier layer can be developed with water by rubbing for 90 seconds △: The barrier layer can be developed with water by rubbing for 120 seconds ×: Water-development of barrier layer is not possible with brush rubbing for 120 seconds

Edge reproducibility of relief halftone dot top: The shape of the 150% line 2% halftone dot top was evaluated using a CTP layer equivalent to 150% 2 line negative film. The evaluation was performed by observing a cross section of the shape of a 150% line 2% halftone dot enlarged by 100 times using a microscope, and judged according to the following criteria.

：: The diameter of the flat portion at the top of the halftone dot reproduces the equivalent of 2% of 150 lines of the negative film, and the end portion has no roundness.
Δ: The diameter of the flat portion at the top of the halftone dot is smaller than the equivalent of 2% of 150 lines of the negative film, and the shape of the end is round.
×: No flat part was observed at the top of the halftone dot, and the shape of the end was round.

  Measurement of indentation displacement: A disc-shaped indenter having a diameter of 10 mm was applied to a printing original plate having a photosensitive resin layer having a thickness of 1.70 mm placed on a support with a load of 120 g for 60 seconds. The displacement was measured using LINEAR SENSOR (GS-112) manufactured by ONO SOKKI. The greater the indentation displacement, the more flexible the plate.

Example 1
The heat-sensitive mask layer prepared in <Preparation of heat-sensitive mask layer> was prepared. Next, a coating liquid composition was prepared in accordance with <Preparation of coating liquid composition for barrier layer> at a barrier layer composition ratio of Example 1 shown in Table 1. Next, according to <Preparation of film of thermal mask layer laminated body provided with barrier layer>, a barrier layer is applied and dried on thermal mask layer so as to have a thickness of 1.5 μm, and a barrier layer is provided on the uppermost layer. A heat-sensitive mask layer laminate film was obtained. The obtained film of the heat-sensitive mask layer laminate is laminated with a photosensitive resin layer according to <Preparation of printing original plate>, and a PET support, an adhesive layer, a photosensitive resin layer, a protective layer, a heat-sensitive mask layer, and a release-treated PET protective film. A flexographic printing original plate comprising (cover film) was obtained. The total thickness of the plate was 1.90 mm. The photosensitive resin layer used in Example 1 was the one prepared in <Preparation of photosensitive resin composition for photosensitive resin layer>.

Examples 2 to 9, Comparative Examples 1 to 5
According to the manufacturing method of Example 1, the photosensitive resin layer of Example 1 was provided using the film provided with the thermal mask layer prepared with the thermal mask layer composition (mass ratio) shown in Table 1, and the PET support, the adhesive, A flexographic printing original plate comprising a layer, a photosensitive resin layer, a barrier layer, a heat-sensitive mask layer, and a release-treated PET protective film (cover film) was obtained. The total thickness of the plate was 1.90 mm. Performance evaluation was performed using the obtained heat-sensitive mask layer and the CTP flexographic printing original plate. The results of these performance evaluations are shown in Table 1 below.

  As can be seen from Table 1, Examples 1 to 9 satisfying the constitutional requirements of the present invention are excellent in all of the wrinkle resistance, the coatability of the barrier layer, the water developability, and the edge reproducibility of the relief halftone dot top. On the other hand, Comparative Example 1 in which the content of polyethylene glycol in the polyamide resin is small is inferior in wrinkle resistance. Comparative Example 2 in which the content of the polyamide resin (B) is high in the content of the polyethylene glycol in the polyamide resin is poor in edge reproducibility of the relief halftone dot top. A polyamide resin in which the number average molecular weight of polyethylene glycol in the polyamide resin is less than 400 and the number average molecular weight exceeds 1000 has poor coatability.

  According to the present invention, there is provided a photosensitive CTP having a high-performance barrier layer, which is capable of preventing wrinkles from occurring in a low-temperature and low-humidity environment and obtaining a flat-top shape having no thick highlight dots. A flexographic printing original plate can be provided. Therefore, the present invention is extremely useful.

Claims (4)

  A photosensitive CTP flexographic printing original plate comprising at least (A) a support, (B) a photosensitive resin layer, and (C) a heat-sensitive mask layer sequentially laminated, wherein (C) a heat-sensitive mask layer and (B) a photosensitive resin. Water-developable photosensitivity, wherein a (D) barrier layer comprising a polyamide resin containing 15 to 35% by mass of a polyether derived from polyethylene glycol or a polyethylene glycol copolymer in the molecule is provided between the layer and the layer. CTP flexographic printing original plate.   The water developable according to claim 1, wherein the polyether contained in the molecule of the polyamide resin in the (D) barrier layer is a polyether amide or a polyether ester amide having a number average molecular weight of 400 to 1,000. A photosensitive CTP flexographic printing original plate.   The water-developable photosensitive CTP flexographic printing plate precursor according to claim 1 or 2, wherein the polyamide resin (A) is a polyamide containing a piperazine ring in a molecule. (B) The photosensitive relief printing plate according to any one of claims 1 to 3, wherein the photosensitive resin composition used for the photosensitive resin layer contains a polymer obtained from an aqueous dispersion latex as a synthetic polymer compound. Printing original plate.