JP2018091953A - Flexographic printing original plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexographic printing original plate including a gas barrier layer having gas barrier properties and solvent dispersibility in a balanced manner.SOLUTION: A flexographic printing original plate includes a layer (A) with an oxygen permeability equal to or lower than 2000 cc 20 μm/m24hr atm, and a solubility parameter of 10.0-24.0 MPa.SELECTED DRAWING: None

Description

  The present invention relates to a flexographic printing original plate.

  A flexographic printing plate used for flexographic printing, which is a type of relief printing, generally has a resin film as a support, and a photosensitive resin layer is laminated on the support. By forming irregularities on the photosensitive resin layer, that is, making a plate, a flexographic printing plate can be obtained. The flexographic printing plate is produced, for example, as follows.

  First, a uniform cured layer is provided by back exposure in which ultraviolet rays are applied to the entire surface of the photosensitive resin layer through a resin film. Next, the black layer is removed by drawing the black film on the photosensitive resin layer by irradiating a laser. Furthermore, by performing relief exposure in which the photosensitive resin layer is irradiated with ultraviolet rays through the black layer, the portion where the black layer is removed is photocured. Thereafter, a portion of the photosensitive resin layer that has not been exposed (that is, a portion that has not been photocured) is removed to form a relief image, which is a desired image, and a flexographic printing plate can be obtained.

The relief image includes a plurality of printed dots, and the shape of the printed dots and the depth of the relief affect the quality of the printed image. In addition, when oxygen is present during relief exposure, oxygen radicals generated from such oxygen inhibit the photocuring reaction, and the photocuring of the photosensitive resin layer becomes insufficient.
Therefore, in Patent Document 1 and Patent Document 2, on the photocurable layer for the purpose of adjusting the shape of the printed dots and making the structure of the printed dots a flat top and a steep shoulder. Laminating a laser ablationable mask layer is disclosed.
Patent Document 3 discloses that at least one barrier layer is provided on a flexographic printing plate for the purpose of covering the surface of an adhesive photopolymerizable layer and blocking oxygen in the atmosphere. Has been.

  Further, in the cited document 4, in a photosensitive resin printing plate precursor including a photosensitive resin and a heat sensitive mask layer, in order to prevent the heat sensitive mask layer from being peeled off and scratches and wrinkles entering the layer, there is a photosensitive property. It is disclosed that an adhesive force adjusting layer containing partially saponified polyvinyl acetate having a saponification degree of 60 mol% or more is provided between the resin and the thermal mask layer.

Special table 2014-512576 gazette Special table 2014-507777 gazette JP 7-506201 A JP 2005-326442 A

  In general, when forming a relief image by removing a non-exposed portion of the photosensitive resin layer, the photosensitive resin is formed by a method such as water development using water, solvent development using a solvent, or heat development using heat. Unexposed portions of the layer are removed. In the solvent development, the photosensitive resin plate subjected to the relief exposure is washed with a solvent. Therefore, the gas barrier layer is required to be easily removed with a solvent while having sufficient gas barrier properties.

Cited Document 1 discloses that the oxygen diffusion coefficient of the barrier layer is less than 6.9 × 10 ⁻⁹ m ² / sec, and it is said that the barrier layer can block oxygen, but a relief image is formed. In this case, the unexposed portion of the photosensitive resin layer including the barrier layer cannot be sufficiently removed by solvent development.
In addition, the layers provided on the surface of the photopolymerizable layer disclosed in the cited documents 2 to 4 are also not sufficiently removable with a solvent while having sufficient gas barrier properties.
In view of the above problems, an object of the present invention is to provide a flexographic printing plate having a gas barrier layer that is excellent in balance between gas barrier properties and solvent dispersibility.

As a result of intensive studies to solve the above problems, the present inventors have found that a gas barrier layer having a specific oxygen permeability and a specific solubility parameter has an excellent balance between gas barrier properties and solvent dispersibility. The invention has been completed.
That is, the present invention includes the following aspects.

[1]
A flexographic printing plate having a layer (A) having an oxygen permeability of 2000 cc · 20 μm / m ² · 24 hr · atm or less and a solubility parameter of 10.0 to 24.0 MPa ^1/2 .
[2]
The flexo according to [1], further comprising a layer (B) containing a photosensitive resin composition, wherein the adhesive force between the layer (A) and the layer (B) containing the photosensitive resin composition is 50 gf / inch or more. Original printing.
[3]
The flexographic printing plate precursor according to [1] or [2], wherein the layer (A) contains polyvinyl alcohol and polyurethane.
[4]
The polyvinyl alcohol is a saponified product of a vinyl carboxylate polymer,
The flexographic printing plate precursor according to [3], wherein the saponification rate of the polyvinyl alcohol is 50% or more.
[5]
The flexographic printing plate precursor according to [4], wherein the saponification rate is 80% or less.
[6]
The flexographic printing plate precursor according to any one of [3] to [5], wherein a mass ratio (PVA: PU) of the polyvinyl alcohol (PVA) and the polyurethane (PU) is 60:40 to 90:10.
[7]
The flexographic printing plate precursor according to any one of [3] to [6], wherein the layer (A) is 1 μm to 20 μm.
[8]
A flexographic printing plate made from the flexographic printing original plate according to any one of [1] to [7].

  The flexographic printing plate precursor of the present invention can provide a flexographic printing plate by making a plate. Moreover, the gas barrier layer in the flexographic printing original plate of the present invention is excellent in the balance between gas barrier properties and solvent dispersibility.

It is the schematic which shows the structure of the flexographic printing original plate of this embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the present embodiment described below, and can be implemented with various modifications within the scope of the gist.

[Flexo printing original plate]
The flexographic printing original plate of this embodiment has a layer (A) having an oxygen permeability of 2000 cc · 20 μm / m ² · 24 hr · atm or less and a solubility parameter of 10.0 to 24.0 MPa ^1/2 .

  Generally, a flexographic printing plate precursor has a layer (B) containing a photosensitive resin composition on a support, and can be further excised on the layer (B) with an infrared laser depending on the properties of the plate. A black layer layer. The flexographic printing plate of the present embodiment preferably further has a layer (A) in the general flexographic printing original plate.

(Layer (A))
The layer (A) in the present embodiment has the ability to block oxygen in order to prevent insufficient curing during relief exposure of the layer (B) containing the photosensitive resin composition, and is removed during solvent development. Therefore, it has dispersibility in a developing solvent.

The ability to block oxygen is generally expressed by oxygen permeability, that is, the volume of oxygen passing through a certain area within a certain time at normal temperature and normal pressure. Materials that can block oxygen more have a low oxygen permeability.
The oxygen permeability can be measured by a method such as JIS-K-7126.
From the viewpoint of sufficiently curing a photosensitive resin composition, the oxygen permeability of layer (A) is Ideally a ^{0cc · 20μm / m 2 · 24hr} · atm, 2000cc · 20μm / m 2 · 24hr · atm Or less, preferably 1500 cc · 20 μm / m ² · 24 hr · atm or less, more preferably 1000 cc · 20 μm / m ² · 24 hr · atm or less.
Specifically, the oxygen permeability of the layer (A) in the present embodiment can be measured by the method described in Examples described later.
Further, the oxygen permeability of the layer (A) in the present embodiment can be adjusted by appropriately selecting materials. Furthermore, even with materials having the same chemical formula, the oxygen permeability can be controlled to be lower by various methods. As various methods, for example, when the material constituting the layer (A) including a material having a certain chemical formula is processed into a film shape, the crystal structure of the film is changed by stretching to reduce the oxygen permeability. And the like.

The solubility parameter is a parameter specific to a substance introduced to estimate the affinity between the solvent and the solute, and a good solubility can be obtained by a combination of the solvent and the solute having closer solubility parameters. Hildebrand, Hansen, etc. are known as the solubility parameter, and the solubility parameter in this specification refers to the Hildebrand solubility parameter. Details of the Hildebrand solubility parameter are described in “POLYMER HANDBOOK” (Fourth Edition, pp. 675-714, John Wiley & Sons, Inc. 1999) and the like.
The solubility parameter of the layer (A) in the present embodiment can be obtained from the material constituting the layer (A). Further, when the layer (A) in the present embodiment is composed of a plurality of materials, the sum of values obtained by multiplying the solubility parameter of each material by the mass ratio of the material to the total mass of the layer (A) is the layer ( The solubility parameter of A).

The layer (A) in the flexographic printing plate precursor according to the present embodiment has a solubility parameter of 10.0 to 24.0 MPa ^1/2 from the viewpoint of maintaining a high oxygen permeability and a good balance with solvent dispersibility. Yes, 13.0 to 24.0 MPa ^1/2 is preferable, 15.0 to 24.0 MPa ^1/2 is more preferable, and 20.0 to 24.0 MPa ^1/2 is more preferable. Further preferred.

  In this embodiment, the layer (A) is laminated adjacent to the layer (B) containing the photosensitive resin composition. From the viewpoint of preventing the layer (A) from being peeled off from the layer (B) containing the photosensitive resin composition at the time of plate making and preventing the layer (A) from being wrinkled, the layers (A) and (B) The adhesive strength is preferably 50 gf / inch or more, more preferably 100 gf / inch or more, and further preferably 150 gf / inch or more. Further, the adhesive force between the layer (A) and the layer (B) is preferably 2000 gf / inch or less, more preferably 1500 gf / inch or less, from the viewpoint of detergency of the layer (A) during development. Preferably, it is 1000 gf / inch or less.

The material constituting the layer (A) is not particularly limited as long as the oxygen permeability and solubility parameters fall within the above ranges. For example, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl acetate, polyvinyl Butyral, polyvinylpyrrolidone, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyacetal, polycarbonate, polystyrene, polycarbonate, polyethylene, polypropylene, cellulose derivatives, polyester, polyamide, polyimide, polyurethane , Silicon rubber, butyl rubber, and isoprene rubber. These materials may be used alone or in combination.
Among these materials, polyvinyl alcohol and polyurethane are preferable, and a combination of polyvinyl alcohol and polyurethane is more preferable.

The polyvinyl alcohol is preferably produced by saponifying polyvinyl acetate. Saponification means hydrolyzing the acetyl group of polyvinyl acetate, and the ratio of the acetyl group of polyvinyl acetate replaced with hydrogen is called the saponification rate or saponification degree.
In general, polyvinyl alcohol having a saponification rate of 98% or more is called completely saponified polyvinyl alcohol, and polyvinyl alcohol having a saponification rate of less than 98% is called partially saponified polyvinyl alcohol. The polyvinyl alcohol in this specification includes both fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol.
Since the higher the saponification rate is, the higher the saponification rate is, the better the oxygen barrier property, the saponification rate of polyvinyl alcohol is preferably 50% or more. The saponification rate of polyvinyl alcohol is more preferably 60% or more, and further preferably 65% or more, from the viewpoint of solubility in a developer.
The saponification rate of polyvinyl alcohol is preferably 100% or less, more preferably 85% or less, and still more preferably 80% or less, from the viewpoint of solubility in a developer.

The polyurethane is not particularly limited as long as it is a polymer having a urethane bond, and examples thereof include polyurethane obtained by reacting a polyol compound and polyisocyanate.
In order to stably dissolve or disperse the polyurethane in an organic solvent and / or water, it is also preferable to add a hydrophilic group-containing compound as a polymerization component in addition to the polyol compound and the polyisocyanate.

  As said polyol compound, polyether polyol, polyester polyol, polyacryl polyol, etc. are mentioned, for example. Among these, polyether polyol is preferable. Examples of the polyether polyol include a polyether polyol obtained by ring-opening copolymerization of an ion polymerizable cyclic compound with a polyhydric alcohol, that is, a reaction product of a polyhydric alcohol and an ion polymerizable cyclic compound.

  Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, Bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, hydroquinone, naphthohydroquinone, anthrahydroquinone, 1,4-cyclohexanediol, tricyclodecanediol, tricyclodecane dimethanol, pentacyclopentadecanediol, and pentacyclo Examples include pentadecane dimethanol. These can be used alone or in combination of two or more.

  Examples of the ion polymerizable cyclic compound include ethylene oxide, propylene oxide, 1,2-butylene oxide, butene-1-oxide, isobutene oxide, 3,3-bischloromethyloxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 3- Methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monooxide, isoprene monooxide, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, Cyclic agents such as butyl glycidyl ether and benzoic acid glycidyl ester Le acids and the like. These can be used alone or in combination of two or more.

  Further, a polyether polyol obtained by ring-opening copolymerization of the above ion-polymerizable cyclic compound with a cyclic imine such as ethyleneimine, a cyclic lactone acid such as β-propiolactone or glycolic acid lactide, or a dimethylcyclopolysiloxane. It can also be used. The ring-opening copolymer of these ion-polymerizable cyclic compounds may be bonded at random or may be bonded in a block shape.

  As said polyisocyanate, the polyisocyanate generally used for manufacture of a polyurethane can be especially used without a restriction | limiting. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethylphenylene diisocyanate, 4,4′-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate , Methylene bis (4-cyclohexyl isocyanate), 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanatoethyl) fumarate, 6-isopropyl 1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 2,5 (or 6) -bis (isocyanatomethyl) -bicyclo [2.2.1] heptane and the like. These polyisocyanates can be used alone or in combination of two or more.

  The number average molecular weight of the polyurethane resin used in the present embodiment is preferably 1,000 to 200,000, and more preferably 30,000 to 100,000.

When an aqueous solvent is used as a polyurethane solvent in the formation of the layer (A) described later, a dispersant may be used, or a functional group such as a carboxyl group, a sulfonyl group, or an ammonium group may be introduced into the polyurethane resin. The above aqueous system means a solvent containing water.
Further, the layer (A) may contain other components such as a surfactant, an anti-blocking agent, and a release agent as long as the gas barrier property and the cleaning property are not impaired.

  In the plate making, since the layer (B) containing the photosensitive resin composition is relief-exposed through the layer (A), the layer (A) is preferably capable of transmitting the wavelength of a light source used for relief exposure. .

The lower limit of the thickness of the layer (A) is preferably 1 μm or more, and more preferably 2 μm or more. When the layer (A) is thinner than 1 μm, the variation in formability increases, and a sufficient effect tends not to be obtained.
Further, the upper limit value of the thickness of the layer (A) is preferably 20 μm or less, and more preferably 10 μm or less. When the thickness of the layer (A) is greater than 20 μm, the image reproducibility of the printing plate tends to be lowered.

(Layer (B))
The layer (B) containing the photosensitive resin composition contains at least one photosensitive resin composition. As the photosensitive resin composition, known materials can be used. The photosensitive resin composition used for the flexographic printing original plate is a resin composition containing a binder, a monomer, and a polymerization initiator. In addition to the binder, the monomer, and the polymerization initiator, other components may be added to the layer (B) as long as the photosensitivity is not impaired.

The binder in the said photosensitive resin composition is a polymer used as the main body of the photosensitive resin composition. Since the properties of the binder greatly affect the properties of the flexographic printing plate after plate making, it is preferably an elastomer. Specific examples of the binder include natural or synthetic polymers of conjugated diene hydrocarbons; polymers of vinyl aromatic hydrocarbons; These polymers can be used alone or in combination of two or more.
As the binder, a block copolymer including a polymer block mainly composed of conjugated diene hydrocarbon and a polymer block mainly composed of vinyl aromatic hydrocarbon is preferable.

Examples of the conjugated diene hydrocarbon include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, And monomers such as 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, and chloroprene. Among these, isoprene and 1,3-butadiene are preferable from the viewpoint of wear resistance.
These monomers may be used alone or in combination of two or more.

Examples of the vinyl aromatic hydrocarbon include, but are not limited to, styrene, t-butylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-dimethyl-p-aminoethylstyrene, Examples thereof include monomers such as N, N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, tertiary butylstyrene, α-methylstyrene, 1,1-diphenylethylene. Among these, styrene is preferable from the viewpoint that the photosensitive resin constituent for a printing plate can be molded smoothly at a relatively low temperature.
These monomers may be used alone or in combination of two or more.

The monomer in the photosensitive resin composition is a compound having an unsaturated double bond capable of radical polymerization.
Monomers include, but are not limited to, for example, esters such as acrylic acid, methacrylic acid, fumaric acid, maleic acid; derivatives of acrylamide and methacrylamide; allyl esters, styrene and derivatives thereof; N-substituted maleimides Compound; and the like.

Specific monomers include diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butylene glycol diacrylate and dimethacrylate; trimethylolpropane Tri (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, isobornyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, pentaerythritol tetra (meth) acrylate, N, N′-hexamethylenebisacrylamide and Methacrylamide, styrene, vinyl toluene, divinyl benzene, diacryl phthalate, triallyl cyanurate , Diethyl fumarate, dibutyl fumarate, dioctyl fumarate, distearyl fumarate, butyl octyl fumarate, diphenyl fumarate, dibenzyl ester fumarate, dibutyl maleate, dioctyl maleate, Examples thereof include bis (3-phenylpropyl) fumarate, dilauryl fumarate, dibehenyl fumarate, N-lauryl maleimide and the like.
These may be used alone or in combination of two or more.

  The polymerization initiator in the photosensitive resin composition is a compound that absorbs light energy and generates radicals, and various known polymerization initiators can be used. Examples of the polymerization initiator include various organic carbonyl compounds. Among them, aromatic carbonyl compounds are preferable.

The polymerization initiator is not limited to the following, and specifically includes benzophenone, 4,4-bis (diethylamino) benzophenone, t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, Thioxanthones such as isopropylthioxanthone and 2,4-dichlorothioxanthone; diethoxyacetophenone, 2,2-methoxy-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1- Acetophenones such as hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; Benzoy Benzoin ethers such as methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl Acylphosphine oxides such as phosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; methylbenzoyl formate; 1,7-bisacridinylheptane; 9-phenylacridine;
These may be used alone or in combination of two or more.

  In the photosensitive resin composition described above, in addition to the binder, the monomer, and the polymerization initiator, there are various auxiliary additive components as long as the photosensitivity is not impaired, for example, a plasticizer and a thermal polymerization inhibitor. UV absorbers, antihalation agents, light stabilizers and the like can be added.

Examples of the plasticizer include, but are not limited to, hydrocarbon oils such as naphthenic oil and paraffin oil; and liquid dienes such as liquid acrylonitrile-butadiene copolymer and liquid styrene-butadiene copolymer. Conjugated diene rubbers such as polystyrene, sebacic acid ester, phthalic acid ester having a number average molecular weight of 2,000 or less.
These plasticizers may be provided with a photopolymerizable reactive group, or may be used alone or in combination of two or more.

  The photosensitive resin composition can be prepared by adding the auxiliary additive component to the binder, the monomer, and the polymerization initiator, if necessary, and mixing with a kneader.

When the total mass of the photosensitive resin composition is 100 parts by mass, the blending amount of the binder is preferably 30 to 90 parts by mass, and more preferably 50 to 70 parts by mass.
When the total mass of the photosensitive resin composition is 100 parts by mass, the compounding amount of the monomer is preferably 1 to 30 parts by mass, and more preferably 3 to 15 parts by mass.
When the total mass of the photosensitive resin composition is 100 parts by mass, the blending amount of the polymerization initiator is preferably 0.1 to 5.0 parts by mass, and 0.5 to 3.0 parts by mass. It is more preferable.
Moreover, when the photosensitive resin composition contains a plasticizer as an auxiliary additive component, the blending amount of the plasticizer is preferably 10 to 40 parts by mass, and more preferably 15 to 35 parts by mass. Furthermore, when the photosensitive resin composition contains a thermal polymerization inhibitor as an auxiliary additive component, the blending amount of the thermal polymerization inhibitor is preferably 0.1 to 5.0 parts by mass, and 0.5 to 3 More preferably, it is 0.0 parts by mass.

(Support)
The flexographic printing plate precursor according to this embodiment preferably has a configuration in which a photosensitive resin composition layer is laminated on a support.
The support used in the flexographic printing plate precursor according to the present embodiment is not limited to the following, and examples thereof include polyester films such as polypropylene film, polyethylene film, polyethylene terephthalate, and polyethylene naphthalate; polyamide films; It is done. Among these, a polyester film is preferable.
The support is preferably a dimensionally stable polyester film having a thickness in the range of 75 to 300 μm.

An adhesive layer may be provided on the support in order to improve the adhesion between the support and the photosensitive resin composition layer.
The material for forming the adhesive layer is not limited to the following, but, for example, a composition having a polymer such as polyurethane, polyamide, or thermoplastic elastomer, and an adhesive active component such as an isocyanate compound or an ethylenically unsaturated compound. Things.
The adhesive layer contains various auxiliary additives such as plasticizers, thermal polymerization inhibitors, UV absorbers, antihalation agents, light stabilizers, photopolymerization initiators, photopolymerizable monomers, dyes, etc. May be.

(Black layer)
The black layer can be excised with an infrared laser, contains a substance soluble in a solvent used as a cleaning solution, and is preferably a thin and flexible black layer. The material for forming the black layer that can be cut with an infrared laser is not limited to the following, and examples thereof include crystalline 1,2-polybutadiene, soluble polyamide, polyvinyl alcohol, and cellulose ester. Among these, soluble polyamide is preferable. These substances may be dissolved in a suitable solvent and the solution may be directly coated on the surface of the flexographic printing plate. The film may be coated on a film of polyester, polypropylene, etc., and this film is laminated and transferred to the flexographic printing plate. May be.

  The black layer that can be removed with an infrared laser is simultaneously removed by dissolution or the like when the unexposed portion is washed out during plate making of the flexographic printing original plate.

(Cover layer)
In the flexographic printing plate precursor according to this embodiment, a cover layer is preferably laminated on the black layer from the viewpoint of protecting the black layer and facilitating handling of the flexographic printing plate.
The cover layer used in the flexographic printing plate precursor according to the present embodiment is not limited to the following, but examples include polyester films such as polypropylene film, polyethylene film, polyethylene terephthalate, and polyethylene naphthalate; polyamide film; It is done. Among these, a polyester film is preferable.
The cover layer is preferably a dimensionally stable polyester film having a thickness in the range of 75 to 300 μm.

A preferred form of the flexographic printing plate precursor according to this embodiment can be represented by a flexographic printing plate precursor 1 shown in FIG.
When the flexographic printing master 1 is a master capable of drawing with an infrared laser, the flexographic printing master 1 includes a cover layer 2, a black layer 3, a layer (A) 4, a layer (B) 5, an adhesive layer 6, and a support 7.
The adhesive layer 6 is laminated on the first surface of the support 7,
The layer (B) 5 is laminated on the side opposite to the first surface of the support 7 to which the adhesive layer 6 is bonded, and adjacent to the adhesive layer 6.
The layer (A) 4 is laminated on the side opposite to the surface of the adhesive layer 6 on which the layer (B) 5 is laminated, and adjacent to the layer (B) 5,
The black layer 3 is laminated on the side opposite to the surface of the layer (B) 5 on which the layer (A) 4 is laminated, and adjacent to the layer (A) 4,
The cover layer 2 is laminated on the side opposite to the surface of the layer (A) 4 on which the black layer 3 is laminated and adjacent to the black layer 3.

[Method of manufacturing flexographic printing plate precursor]
For example, when the flexographic printing original plate of the present embodiment is an original that can be drawn with an infrared laser, it can be manufactured by a manufacturing method including the following steps.
Laminating an adhesive layer on a support;
Laminating a black layer on the cover sheet;
A step of laminating the layer (A) on the black layer of the cover sheet on which the black layer is laminated;
A photosensitive resin composition is laminated on the adhesive layer, and the photosensitive resin composition is used as a support so that the layer (A) laminated on the cover sheet faces the photosensitive resin composition. Sandwiching with the cover sheet;

  In the step of laminating the adhesive layer on the support, the material for forming the adhesive layer is applied to the support with a knife coater or the like. The material for forming the adhesive layer is preferably a solution dissolved in an organic solvent such as toluene from the viewpoint of application workability, and is a solution dissolved in an organic solvent having a solid content of 5 to 40%. More preferably. The support body which has an adhesive bond layer can be obtained by apply | coating the forming material of an adhesive bond layer, and drying.

  In the step of laminating the black layer on the cover sheet, the material for forming the black layer is applied to the cover sheet by a knife coater or the like. The material for forming the black layer is preferably a solution dissolved in an organic solvent such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate from the viewpoint of coating workability, and the solid content is 5 to 30%. More preferably, the solution is dissolved in an organic solvent. The cover sheet which has a black layer can be obtained by apply | coating the material which forms a black layer, and drying.

  In the step of laminating the layer (A) on the black layer of the cover sheet on which the black layer is laminated, the material constituting the layer (A) is a knife coater or the like on the black layer side of the cover sheet having the black layer. Applied by. The material constituting the layer (A) is preferably a solution dissolved in an organic solvent from the viewpoint of coating workability, and is a solution dissolved in an organic solvent having a solid content of 5 to 30%. It is more preferable. The solution may contain water. A cover sheet having the layer (A) and the black layer can be obtained by applying the material constituting the layer (A) and then drying.

  In the step of sandwiching the photosensitive resin composition between the support and the cover sheet, the support having the adhesive layer, the cover sheet having the layer (A) and the black layer, the adhesive layer and the layer (A) The photosensitive resin composition is sandwiched between a support and a cover sheet so as to face the photosensitive resin composition, and heated and compression molded to obtain a flexographic printing original plate.

[Flexographic printing plate]
The flexographic printing plate of the present embodiment can be manufactured by processing the flexographic printing original plate of the present embodiment. Hereinafter, an example of a manufacturing method is shown.
First, it exposes through a support body and photocures the photosensitive resin composition layer, and provides a thin uniform cured layer (back exposure).
Next, after the black layer layer is laser-drawn, image exposure (relief exposure) is performed directly on the surface of the photosensitive resin layer from above the black layer layer.
Thereafter, the unexposed portion (that is, the portion that has not been photocured) is washed with a developing solution to form a desired image, that is, a relief image, and a flexographic printing plate is obtained.

The light source used for photocuring the flexographic printing original plate is not limited to the following, and examples thereof include a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, and sunlight.
Either the exposure from the top of the black layer layer or the exposure from the support side may be performed first, but from the viewpoint of image reproducibility, the exposure from the support side is preferably performed first.

Examples of the developing solvent include, but are not limited to, chlorinated organic solvents such as 1,1,1-trichloroethane and tetrachloroethylene; ester solvents such as heptyl acetate and 3-methoxybutyl acetate; And hydrocarbon solvents such as distillate, toluene and decalin; Further, as the developing solvent, a solvent obtained by mixing alcohols such as propanol, butanol and pentanol with the above solvent can be used. The solubility parameter of these solvents is preferably in the range of 12-20 MPa ^1/2 .

  Hereinafter, the present embodiment will be described in more detail using examples and the like, but the present embodiment is not limited to these examples.

〔Evaluation method〕
Below, the evaluation method of the evaluation item in Table 1 is shown.
(1) Evaluation of formability 120 lpi of the printing plates obtained in [Example] and [Comparative Example] to be described later are observed with a scanning electron microscope (SEM) of a 2% halftone dot portion to sufficiently block oxygen. The case where the surface was cured and formed was marked with ◯, the case where the surface was cured but insufficiently formed was marked with Δ, and the case where it was not formed was marked with ×. Excellent moldability means excellent gas barrier properties.

(2) Evaluation of detergency The printing plates obtained in [Example] and [Comparative Example] to be described later are visually observed. When the layer A is not left at all, the resin layer in the unexposed area is removed. Although the layer (A) was not slightly left in the exposed portion, Δ was marked, and the case where the resin layer in the unexposed portion was not removed was marked x.

(3) Evaluation of adhesion The printing original plate obtained in [Example] and [Comparative Example] described later is cut into 10 cm × 2.54 cm, and the support side is fixed to the test plate with a double-sided tape, and then the layer (A ) Was peeled off from the layer (B) containing the photosensitive resin composition in the long side direction, the layer (A) was folded back and pulled at a speed of 50 mm / min in the 180 ° direction, and the adhesive force was measured. When the adhesive force was 0 or more and less than 50 gf / inch, x, when the adhesive force was 50 gf / inch or more and less than 100 gf / inch, Δ, when the adhesive force was 100 gf / inch or more and less than 150 gf / inch The case was marked as ◯, and the case where the adhesive strength was 150 gf / inch or more was marked as ◎.

(4) Evaluation of durability Using the printing plates obtained in [Examples] and [Comparative Examples] described later, printing was performed under the following conditions. In addition, [Comparative Example 2] was not evaluated because the detergency was insufficient and an evaluable sample could not be obtained.
The area ratio of 120 lpi and 5% halftone dots of the printing plate was measured with an image processing analyzer Luzex AP (Nireco Corporation) before and after printing, and the rate of change in area ratio before and after printing was calculated. The case where the change of the area ratio was 0% or more and less than 5% was evaluated as ◯, and the case where it was 5% or more was evaluated as ×.
For printing, process X cyan (trade name, manufactured by Toyo Ink Manufacturing Co., Ltd.) was used for the ink, and K liner paper was used for the substrate. Anilox roll was 250 lpi, cushion tape was 3M1020 (trade name, manufactured by Sumitomo 3M Limited), and printing speed was 200 m / min and 4000 m printing was performed.

(5) Measurement of oxygen permeability Layer (A) is peeled from the cover sheet obtained in [Example] and [Comparative Example] (production of cover sheet comprising layer (A) and black layer) described later, The oxygen permeability was measured. OX-TRAN 2/22 (MOCON, trade name) was used for the measurement of oxygen permeability. When the oxygen permeability is 0 cc · 20 μm / m ² · 24 hr · atm or more and less than 1000 cc · 20 µm / m ² · 24 hr · atm, A, 1000 cc · 20 µm / m ² · 24 hr · atm or more, 1500 cc · 20 µm / The case of less than m ² · 24 hr · atm is B, 1500 cc · 20 μm / m ² · 24 hr · atm or more, and the case of less than 2000 cc · 20 µm / m ² · 24 hr · atm is C, 2000 cc · 20 µm / m ² -The case where it was more than 24hr.atm was set to D.

[Example 1]
(Production of photosensitive resin composition)
The photosensitive resin composition was manufactured under the conditions in which the raw materials shown below were charged into a kneader (Paurec Co., Ltd., FM-MW-3 type) and mixed at 140 ° C. for 60 minutes.
60 parts by mass of thermoplastic elastomer TR2787 (trade name, manufactured by JSR Corporation), which is a block copolymer of styrene-butadiene as a binder, 10 parts by mass of 1,9-nonanediol acrylate as a monomer, and 2, as a polymerization initiator 2 parts by weight of 2-dimethoxy-phenylacetophenone, 27 parts by weight of Polyvest P130 (product name, manufactured by Degussa), which is a liquid polybutadiene as a plasticizer, and 1 part by weight of dibutylhydroxytoluene as a thermal polymerization inhibitor Parts were kneaded under the above conditions to obtain a photosensitive resin composition.

(Manufacture of a support having an adhesive layer)
As a solution for the adhesive layer to be coated on the support, 55 parts by mass of Taffprene 912 (trade name, manufactured by Asahi Kasei Chemicals Corporation), which is a block copolymer of styrene and 1,3-butadiene, paraffin oil (average) Carbon number 33, average molecular weight 470) 38 parts by mass, 1,9-nonanediol diacrylate 2.5 parts by mass, 2,2-dimethoxy-phenylacetophenone 1.5 parts by mass, epoxy ester 3000M (Kyoeisha Chemical Co., Ltd.) 3 parts by mass (trade name, manufactured by company) and 1.5 parts by mass of Balifast Yellow 3150 (trade name, manufactured by Orient Chemical Industries) were dissolved in toluene to obtain a solution having a solid content of 25%.
Then, using the knife coater, it apply | coated so that it might become 30% of ultraviolet-ray transmittance on the one side of a 100 micrometer-thick polyester film, and it dried at 80 degreeC for 1 minute, and obtained the support body which has an adhesive bond layer.

(Manufacture of cover sheet with black layer)
65 parts by mass of Macromelt 6900 (trade name, manufactured by Henkel), which is a thermoplastic polyamide resin, and 35 parts by mass of carbon black as an infrared sensitive substance were kneaded with a kneader and cut into pellets.
Thereafter, 90 parts by mass of the pellets and 10 parts by mass of 1,6-hexanediol adipate were mixed into a mixed solvent prepared with a mass ratio of ethyl acetate / butyl acetate / propylene glycol monomethyl ether acetate = 50/30/20 by ultrasonication. Was used to prepare a uniform solution having a solid content of 12% by mass.
This solution is applied onto a polyester film serving as a cover sheet having a thickness of 100 μm using a knife coater so that the coating amount after drying is 4 to 5 g / m ^2, and dried at 80 ° C. for 1 minute, and laser A cover sheet having a drawable black layer was obtained.

(Manufacture of cover sheet comprising layer (A) and black layer)
75 parts by mass of JMR-10H (trade name, manufactured by Nippon Vinegar Poval Co., Ltd.), which is a polyvinyl alcohol with a saponification rate of 80%, and Superflex E-2000 (Daiichi Kogyo Co., Ltd.), a polyester urethane resin 25 parts by mass (trade name, manufactured by company) were dissolved in a mixed solvent in which water and ethanol were mixed to prepare a uniform solution having a solid concentration of 10%.
This solution was applied onto the black layer of the “cover sheet having a black layer layer” produced as described above using a knife coater so that the thickness after drying was 3 μm, and the coating was performed at 90 ° C. for 4 minutes. It dried and the cover sheet which has the layer (A) whose ratio of JMR-10H and Superflex E-2000 is 75:25 on the black layer was formed.

(Manufacture of flexographic printing original plate having layer (A))
Next, using the photosensitive resin composition produced as described above, the support having the adhesive layer, and the cover sheet comprising the layer (A) and the black layer, the flexographic printing original plate having the layer (A) is produced. did.
The support is made so that the adhesive layer side of the support is aligned with the photosensitive resin composition produced as described above, and the layer (A) side of the cover sheet faces the photosensitive resin composition. Were covered with a cover sheet and heated and compression-molded so that the whole became 1.5 mm to obtain a flexographic printing original plate.

[Example 2]
Instead of JMR-10H in [Example 1] (production of cover sheet comprising layer (A) and black layer), JMR-10M (Nippon Vinegar / Povar) is a polyvinyl alcohol having a saponification rate of 65%. (Trade name, manufactured by Co., Ltd.) was used.
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 3
In the above [Example 1] (manufacture of a cover sheet having a layer (A) and a black layer), instead of JMR-10H, JMR-10L (Nippon Vinegar / Povar) is a polyvinyl alcohol having a saponification rate of 35%. (Trade name, manufactured by Co., Ltd.).
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 4
60 parts by mass of RS4104 (trade name, manufactured by Kuraray Co., Ltd.), which is polyvinyl alcohol having a saponification rate of 98% in (Example 1) (Manufacture of a cover sheet having a layer (A) and a black layer), Superflex E-2000 was dissolved in a mixed solvent in which 40 parts by mass of water and ethanol were mixed to prepare a uniform solution having a solid content concentration of 10% to obtain a layer (A).
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 5
In the above [Example 1] (Manufacture of cover sheet having layer (A) and black layer), Hydran WLS-202 (DIC Corporation, trade name) which is a polyether polyurethane instead of Superflex E-2000 It was used.
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 6
Superflex 460 (manufactured by Daiichi Kogyo Co., Ltd.), which is a carbonate-based urethane resin, instead of Superflex E-2000 in (Example 1) (Manufacture of cover sheet having layer (A) and black layer) Name).
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 7
In [Example 1] (Manufacture of cover sheet having layer (A) and black layer), 60 parts by weight of JMR-10H, 25 parts by weight of Superflex E-2000, and Pitskor K- which is polyvinylpyrrolidone 30 parts by mass (trade name, manufactured by Daiichi Kogyo Co., Ltd.) was used to obtain a layer (A).
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 8
In [Example 1] (production of cover sheet having layer (A) and black layer), 40 parts by weight of JMR-10H, 40 parts by weight of JMR-10L, and 20 parts by weight of Superflex 460 are used. Layer (A) was obtained.
The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

Example 9
In the above [Example 1] (manufacture of a cover sheet having a layer (A) and a black layer), the above [Examples] except that the layer (A) after drying was applied to a thickness of 1 μm. In the same manner as in 1], a flexographic printing plate precursor was obtained.

Example 10
In the above [Example 1] (Manufacture of a cover sheet having a layer (A) and a black layer), the above [Example] except that the layer (A) after drying was applied to a thickness of 2 μm. In the same manner as in 1], a flexographic printing plate precursor was obtained.

Example 11
In the above [Example 1] (manufacture of a cover sheet comprising a layer (A) and a black layer), the above [Example] except that the layer (A) after drying was applied to a thickness of 5 μm. In the same manner as in 1], a flexographic printing plate precursor was obtained.

[Comparative Example 1]
In [Example 1] (manufacturing the cover sheet comprising the layer (A) and the black layer), in (manufacturing the flexographic printing plate having the layer (A)), the black of the cover sheet comprising the black layer The flexographic printing original plate which does not have a layer (A) was obtained by pinching with a support body and a cover sheet so that the layer side might face the photosensitive resin composition, and compression-molding.

[Comparative Example 2]
In [Example 1] (manufacture of a cover sheet comprising a layer (A) and a black layer), RS4104, which is a polyvinyl alcohol having a saponification rate of 98%, is mixed with 100 parts by mass of water and ethanol. It melt | dissolved and the uniform solution with a solid content concentration of 10% was prepared, and the layer (A) was obtained. The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

[Comparative Example 3]
In [Example 1] (Manufacture of cover sheet having layer (A) and black layer), 100 parts by mass of hydran WLS-202 was dissolved in a mixed solvent of water and ethanol, and the solid content concentration was 10%. A uniform solution was prepared to obtain a layer (A). The other conditions were the same as in Example 1 above to obtain a flexographic printing plate precursor.

[Manufacture of printing plates for characteristic evaluation]
In the printing original plate obtained in [Example] and [Comparative Example] described above, only the polyester film is peeled off so that the black layer layer is transferred to the layer containing the photosensitive resin composition, with the black layer layer on the outside, It was loaded on a drum on “CDI-Spark 4260” (Esko-Graphics, trade name, 1064 nm YAG laser).
Laser power was 20 W, drum rotation speed was 200 rpm, laser drawing was performed on the black layer layer on the printing original plate, and a part of the black layer layer was excised.
Next, on the “AFP-1216E” exposure machine (trade name, manufactured by Asahi Kasei Co., Ltd.), using the lower ultraviolet lamp (UV lamp TL80W / 10R, trade name, manufactured by PHILIPS), the printing plate is first printed from the support side. The entire surface was exposed at 300 mJ / cm ² so that the relief depth was 0.7 mm.
Subsequently, an ultraviolet ray of 8000 mJ / cm ² was irradiated from the black layer side with an upper lamp (UV lamp TL80W / 10R manufactured by PHILIPS, trade name). The exposure intensity at this time was measured with a UV illuminance meter MO-2 type machine (manufactured by Oak Seisakusho, trade name, UV-35 filter) manufactured by Oak Seisakusho.
Next, development is performed at a liquid temperature of 30 ° C. at a rate of 100 mm / min using an “AFP-1321P” developing machine (trade name, manufactured by Asahi Kasei Co., Ltd.) using 3-methoxybutyl acetate as a developer, and at 60 ° C. for 2 hours Dried.
Thereafter, as post-exposure processing, a sterilization lamp (GL-30, trade name, manufactured by Toshiba Corporation) having a central wavelength of 254 nm using AFP-1216LF (trade name, manufactured by Asahi Kasei Co., Ltd.), and photosensitivity after drying. The entire surface of the photosensitive resin plate was exposed to 2000 mJ / cm ² . The post-exposure amount by the germicidal lamp here is calculated from the illuminance measured using the UV-25 filter of the “UV-MO2” machine.

In [Examples 1 to 11], it was found that the formability was improved by the layer (A) and the cleaning property was compatible. Furthermore, the layer (A) had sufficient adhesiveness. That is, the flexographic printing original plates of Examples 1 to 11 are excellent in the balance between gas barrier properties and solvent dispersibility.
Moreover, the flexographic printing plate obtained from the flexographic printing original plate of [Examples 1 to 11] had a small change in the dot area ratio before and after printing, and an unexpected effect of improving durability could be confirmed. The flexographic printing plate has a good balance between gas barrier properties and solvent dispersibility, so that the photo-resin composition can be cured sufficiently, and impurities such as the unexposed resin layer and layer (A) can be removed sufficiently during development. It is considered that the durability was improved because the change in the shape of the printing dots in the flexographic printing plate due to the friction of the foreign matters could be prevented. The reason why the durability is improved is that the surface of the printed dots obtained by developing a part of the polyvinyl alcohol and / or polyurethane in the layer (A) into the surface layer of the photosensitive resin composition layer (B) It is conceivable that the shape was maintained even if the friction due to printing was repeated due to the protection.
[Comparative Example 1] having no layer (A) was poor in formability and did not have sufficient durability.
In [Comparative Example 2], although the formability was improved, most of the unexposed areas remained uncleanable. Further, the adhesion with the layer (B) containing the photosensitive resin composition was extremely low.
In [Comparative Example 3], sufficient detergency and adhesion were shown, but no improvement in formability was obtained.

  In the flexographic printing original plate of the present invention, the layer (A) of the original plate has an excellent balance between gas barrier properties and solvent dispersibility. Moreover, since the flexographic printing plate obtained by making the original plate has high durability, printing productivity is improved.

1: Flexographic printing original plate 2: Cover layer 3: Black layer 4: Layer (A)
5: Layer (B)
6: Adhesive layer 7: Support

Claims (8)

A flexographic printing plate having a layer (A) having an oxygen permeability of 2000 cc · 20 μm / m ² · 24 hr · atm or less and a solubility parameter of 10.0 to 24.0 MPa ^1/2 .   The flexo of claim 1, further comprising a layer (B) containing a photosensitive resin composition, wherein the adhesive force between the layer (A) and the layer (B) containing the photosensitive resin composition is 50 gf / inch or more. Original printing.   The flexographic printing plate precursor according to claim 1 or 2, wherein the layer (A) comprises polyvinyl alcohol and polyurethane. The polyvinyl alcohol is a saponified product of a vinyl carboxylate polymer,
The flexographic printing plate precursor according to claim 3, wherein the saponification rate of the polyvinyl alcohol is 50% or more.   The flexographic printing plate precursor according to claim 4, wherein the saponification rate is 80% or less.   The flexographic printing plate precursor according to any one of claims 3 to 5, wherein a mass ratio (PVA: PU) of the polyvinyl alcohol (PVA) and the polyurethane (PU) is 60:40 to 90:10.   The flexographic printing plate precursor according to any one of claims 3 to 6, wherein the layer (A) is 1 µm to 20 µm.   The flexographic printing plate made from the flexographic printing original plate of any one of Claim 1 to 7.