JP7267777B2 - Original plate for flexographic printing plate - Google Patents

Description

The present invention relates to a flexographic printing plate precursor.

Known printing methods include a method that enables printing by applying a three-dimensional shape to a printing plate, and a method that enables printing by imparting chemical characteristics.
Representative examples of the former include letterpress printing and intaglio printing.
In letterpress printing, printing is possible by depositing ink on the convex portions of the printing plate, while in intaglio printing, printing is possible by depositing ink on the concave portions of the printing plate.
Flexographic printing is a kind of letterpress printing, and since printing is performed using a flexible printing plate made of resin, rubber, or the like, it is characterized by being able to print on a variety of printing materials.

Many of the resin compositions used as materials for flexographic printing plates in recent years are photosensitive resin compositions to which photosensitivity has been imparted in order to form a three-dimensional shape using a lithographic technique.
A photosensitive resin composition for a flexographic printing plate generally contains a thermoplastic elastomer, an ethylenically unsaturated compound, and a photopolymerization initiator.

As a "flexographic printing plate precursor" which is a laminate in the previous stage in which a printing shape is imparted to a photosensitive resin composition layer, a polyester film or the like is used as a support, and a photosensitive resin composition layer is formed thereon. Accordingly, there is known a structure in which a protective layer is provided on the photosensitive resin composition layer for the purpose of smoothing the contact with the negative film, and a cover sheet such as a polyester film is further provided thereon.

In order to make a flexographic printing plate using the flexographic printing plate precursor having the structure described above, first, the entire surface of the photosensitive resin composition layer is exposed to ultraviolet light through the support (back exposure), and the photosensitive resin composition is exposed to light. Polymerizes to form a thin uniform cured layer.
Next, a negative film having a desired image is laminated on the photosensitive resin composition layer, image exposure (relief exposure) is performed on the photosensitive resin composition layer through the negative film, and the image area is cured, After that, the unexposed portion is washed away with a developing solution to remove the unexposed portion, thereby obtaining a photosensitive resin structure on which unevenness for printing is formed.
After that, the surface of the photosensitive resin structure on which the unevenness is formed is subjected to post-treatment exposure to obtain a flexographic printing plate.

In recent years, in response to the increasing demand for improved printing quality, an ablation layer that can be cut with an infrared laser is provided on the photosensitive resin composition layer instead of the conventional plate making technology using a negative film. A so-called digital engraving technique has been developed in which the ablation layer is excised in a desired pattern with a laser, and then exposed to form a portion to be cured with ultraviolet rays and a portion not to be cured with ultraviolet rays.
This digital platemaking technology has the advantage of being able to save time and labor compared to the conventional technology using negative film. For example, when an image is to be corrected, it is possible to easily correct the image by correcting the digitized image data on a computer, without the need to produce a new negative film.

When making a flexographic printing plate using the above-described digital plate making technology, it is desirable that the ablation layer be free of pinholes.
If there are pinholes in the ablation layer, the photosensitive resin composition layer in contact with the pinholes is exposed during relief exposure, resulting in unintended image formation and the problem that good prints cannot be obtained. .

As a method of providing the ablation layer on the photosensitive resin composition layer, there is a method of directly applying the ablation layer to the photosensitive resin composition layer, or a method of applying the ablation layer on the cover sheet and applying the ablation layer side to the photosensitive resin composition layer. A method of stacking by laminating with a resin composition layer and transferring is included.
When the ablative layer is provided on the photosensitive resin composition layer by bonding the ablative layer coated on the cover sheet to the photosensitive resin composition layer, coating unevenness when the ablative layer is applied on the cover sheet, Repelling may cause pinholes in the ablation layer, and impact during storage and transportation of the cover sheet coated with the ablation layer may also cause lamination when it is attached to the photosensitive resin composition layer. There is a problem that pinholes may occur due to temperature/pressure and contact with the kneaded and extruded resin.

In view of such problems, Patent Document 1 discloses that after applying an ablation layer on a cover sheet, a shielding layer laminate is prepared by bonding a release film to the ablation layer, and the release film is peeled off from the shielding layer laminate. However, a technique for suppressing the generation of pinholes in the ablation layer by laminating the layer with a photosensitive resin composition layer is disclosed.
However, the technique disclosed in Patent Document 1 has a problem that pinholes are generated when the release film is peeled off unless the adhesion between the ablation layer and the release film is sufficiently low. there is Moreover, there is also a problem that the adhesiveness between the ablation layer and the photosensitive resin composition layer may be lowered due to the release agent of the release film being transferred to the ablation layer.

As another method for preventing pinholes from occurring in the ablation layer, Patent Document 2 discloses a technique of providing an intermediate layer between the ablation layer and the photosensitive resin composition layer. .
In this technique, since the intermediate layer protects the ablation layer, there is an advantage that pinholes are less likely to occur when the ablation layer and the photosensitive resin composition layer are bonded together.
However, the intermediate layer provided between the ablation layer and the photosensitive resin composition layer remains in the printing plate precursor. When provided, there is a problem that the flexibility of the entire plate is impaired, cracks occur in the intermediate layer and the ablation layer during writing with an infrared laser, and unintended image formation occurs.

Further, a technique of forming an image mask by irradiating an infrared laser onto a photosensitive resin letterpress original plate having a structure in which a photosensitive resin composition layer, a film layer, and an ablation layer are provided on a support has been proposed (for example, , see Patent Document 3).
In this technique, after the entire surface of the formed image mask is exposed to ultraviolet light, the image mask is peeled and removed together with the film layer, and then water-developed to obtain a resin letterpress printing plate. There is an advantage that the material of the ablation layer that constitutes the mask is not mixed, and the development waste liquid can be easily treated. However, if the thickness of the film layer between the photosensitive resin composition layer and the ablation layer is thick, the bending and scattering of the ultraviolet light are likely to occur accordingly, and if a light source of ultraviolet light with low directivity is selected However, there is a problem that the image may be thickened and the accuracy of image formation may be lowered.

Japanese Patent No. 4610132 Japanese Patent No. 2773981 WO 01/18605 pamphlet (pages 2-3, 17)

Therefore, in view of the above-described problems of the prior art, an object of the present invention is to provide a flexographic printing plate precursor that has high resin adhesion in the ablation layer, can suppress pinholes in the ablation layer, and is excellent in handleability. and

As a result of intensive studies to solve the above-mentioned problems, the present inventors found that the above-described problems of the prior art can be solved by arranging an intermediate layer of a specific composition in the flexographic printing plate precursor. The present invention has been completed.
That is, the present invention is as follows.

[1]
a support (A);
a photosensitive resin composition layer (B);
an intermediate layer (C);
an ablation layer (D);
A flexographic printing plate precursor having, in the order,
The intermediate layer (C) contains a water-dispersible latex and a water-soluble polyurethane,
the water-dispersible latex and the water-soluble polyurethane have a polar group,
The content of the water-dispersible latex is 3% by mass or more and 80% by mass or less with respect to the total amount of the intermediate layer (C),
The content of the water-soluble polyurethane is 10% by mass or more and 87% by mass or less with respect to the total amount of the intermediate layer (C).
Original plate for flexographic printing plate.
[2]
The flexographic printing plate precursor as described in [1] above, wherein the water-dispersible latex has a carboxyl group or a hydroxyl group.
[3]
The flexographic printing plate precursor as described in [1] or [2] above, wherein the water-dispersible latex has a toluene gel fraction of 70% by mass or more and 90% by mass or less.
[4]
The content ratio of the water-dispersible latex with respect to the total amount of the intermediate layer (C) is
3% by mass or more and 90% by mass or less,
The flexographic printing plate precursor according to any one of [1] to [3] above.
[5]
The water-soluble polyurethane has a heat softening temperature of 80° C. to 210° C.
The flexographic printing plate precursor according to any one of [1] to [4] above.
[6]
The flexographic printing plate precursor as described in any one of [1] to [5] above, wherein the water-soluble polyurethane has a polyether, polyester or polycarbonate structure in its molecule.
[7]
The above [1], wherein the water-soluble polyurethane has a carboxyl group or a hydroxyl group in the molecule.
The flexographic printing plate precursor according to any one of [6].
[8]
The content ratio of the water-soluble polyurethane with respect to the total amount of the intermediate layer (C) is
10% by mass or more and less than 90% by mass,
The flexographic printing plate precursor according to any one of [1] to [7] above.
[9]
The intermediate layer (C) further contains a water-soluble polyamide,
The flexographic printing plate precursor according to any one of [1] to [8] above.
[10]
The intermediate layer (C) is
For 100 parts by mass of the water-dispersible latex,
10 to 700 parts by mass of the water-soluble polyamide,
The flexographic printing plate precursor as described in [9] above.
[11]
The intermediate layer (C) has a thickness of 0.5 μm or more and 20 μm or less.
The flexographic printing plate precursor according to any one of [1] to [10] above.
[12]
The intermediate layer (C) further contains a silicone compound,
The flexographic printing plate precursor according to any one of [1] to [11] above.
[13]
The ablation layer (D) is
selected from the group consisting of carbon black, an acid-modified polymer, a copolymer composed of a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer, a hydrogenated product of the copolymer, and a modified product of the copolymer; further containing at least one
The flexographic printing plate precursor according to any one of [1] to [12] above.

According to the present invention, it is possible to obtain a flexographic printing plate precursor that has high resin adhesion in the ablation layer, can suppress pinholes in the ablation layer, and is excellent in handleability.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail.
It should be noted that the present invention is not limited to the following description, and various modifications can be made within the scope of the gist of the present invention.

[Original plate for flexographic printing plate]
The flexographic printing plate precursor of the present embodiment comprises a support (A), a photosensitive resin composition layer (B), an intermediate layer (C), and an ablation layer (D) in the order described above. A printing plate precursor for a flexographic printing plate, wherein the intermediate layer (C) contains a water-dispersible latex and a water-soluble polyurethane, and the water-dispersible latex and the water-soluble polyurethane have a polar group. It is the original version.

(Support (A))
Examples of the support (A) used in the flexographic printing plate precursor of the present embodiment include, but are not limited to, polyester films such as polypropylene film, polyethylene film, polyethylene terephthalate, and polyethylene naphthalate; A film etc. are mentioned.
Among these, a polyester film is preferred.
The thickness of the support (A) is also not particularly limited, but a dimensionally stable film of 50 to 300 μm is preferred.
Further, an adhesive layer may be provided on the support (A) for the purpose of increasing the adhesive strength between the support (A) and the photosensitive resin composition layer (B) described later. Layers include, for example, adhesive layers described in International Publication No. 2004/104701.

(Photosensitive resin composition layer (B))
The photosensitive resin composition layer (B) contains at least one elastomer, a photopolymerizable monomer, a photopolymerization initiator, or a photoinitiator system (a system using two or more photopolymerization initiators), and , plasticizers, processing aids, dyes, and UV absorbers.

The elastomer contained in the photosensitive resin composition layer (B) retains its shape after photopolymerization of the photosensitive resin composition and has rubber elasticity.
Examples of such elastomers include, but are not limited to, styrene-diene block copolymers, ethylene-acrylic acid copolymers, polyethylene oxide polyvinyl alcohol graft copolymers, polybutadiene, polyisoprene, styrene-butadiene rubber, nitrile-butadiene. Synthetic rubber such as rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene-isoprene rubber, polynorbornene rubber, or ethylene-propylene-diene rubber (EPDM), natural rubber, latex, polyvinyl alcohol, polyvinyl acetate, partially saponified polyvinyl Vinyl acetate (partially saponified polyvinyl alcohol), cellulose resins, acrylic resins, polyamide resins, polyamide resins with hydrophilic groups such as polyethylene oxide, ethylene/vinyl acetate copolymers, modified products thereof, etc. are dispersed in water. Various resins are possible.
A mixture of two or more of these resins can be used as long as they do not adversely affect plate formability. In particular, a latex having a hydrophilic group, which can provide high detergency with an aqueous detergent, is preferred.

The content of the elastomer in the photosensitive resin composition layer (B) is determined from the viewpoint of the durability of the flexographic printing plate obtained using the flexographic printing plate precursor of the present embodiment. When the total amount of is 100% by mass, it is preferably 30 to 85% by mass, more preferably 40 to 80% by mass, and even more preferably 45 to 75% by mass.

The photopolymerizable monomer contained in the photosensitive resin composition layer (B) is not particularly limited, but examples include carboxylic acid esters such as acrylic acid, methacrylic acid, fumaric acid and maleic acid; derivatives, allyl esters, styrene and its derivatives, N-substituted maleimide compounds, and the like.

Examples of photopolymerizable monomers include, but are not limited to, diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol; diacrylates and dimethacrylates of butylene glycol; trimethylolpropane triacrylate and trimethacrylate; pentaerythrite tetraacrylate and tetramethacrylate, etc.; N,N'-hexamethylenebisacrylamide and methacrylamide; Diacryl phthalate, triallyl cyanurate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, distearyl fumarate, butyl octyl fumarate, diphenyl fumarate, dibenzyl fumarate, dibutyl maleate ester, dioctyl maleate, bis(3-phenylpropyl) fumarate, dilauryl fumarate, dibehenyl fumarate, N-laurylmaleimide and the like.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the photopolymerizable monomer in the photosensitive resin composition layer (B) is determined from the viewpoint of the printing durability of the flexographic printing plate obtained using the flexographic printing plate precursor of the present embodiment. In the production process (B), when the total amount of the photosensitive resin composition is 100% by mass, it is preferably 2% by mass to 30% by mass, more preferably 2% by mass to 25% by mass, More preferably, it is 2% by mass to 20% by mass.

The photopolymerization initiator contained in the photosensitive resin composition layer (B) is not particularly limited, but examples include benzophenone, Michler ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α - methylolbenzoin, α-methylolbenzoin methyl ether, α-methoxybenzoin methyl ether, benzoinphenyl ether, α-t-butylbenzoin, 2,2-dimethoxyphenylacetophenone, 2,2-diethoxyphenylacetophenone, benzyl, pivaloin, anthraquinone, benzanthraquinone, 2-ethylanthraquinone, 2-chloroanthraquinone and the like.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the photopolymerization initiator in the photosensitive resin composition layer (B) is determined from the viewpoint of the printing durability of the flexographic printing plate produced using the flexographic printing plate precursor of the present embodiment. In the production process (B), when the total amount of the photosensitive resin composition is 100% by mass, it is preferably in the range of 0.1 to 10% by mass, and may be in the range of 0.1 to 5% by mass. More preferably, it is in the range of 0.5 to 5% by mass.

The photosensitive resin composition layer (B) contains, as other components, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, trimethylolethane for the purpose of improving compatibility and flexibility. Polyhydric alcohols such as; liquid polybutadiene, polyisoprene, polyacrylic, may further contain modified products of their terminal groups or side chains, and contains a conventionally known polymerization inhibitor to increase thermal stability You may
Polymerization inhibitors include phenols, hydroquinones, catechols and the like.
In addition, dyes, pigments, surfactants, silicone compounds, ultraviolet absorbers, fragrances, antioxidants and the like may be contained.

(Intermediate layer (C))
The flexographic printing plate precursor of this embodiment has an intermediate layer (C) between the photosensitive resin composition layer (B) described above and the ablation layer (D) described later.
The intermediate layer (C) has sufficient film strength to suppress the occurrence of pinholes in the ablation layer (D) described later, and the photosensitive resin composition layer (B) and the ablation layer (D) It preferably has sufficient flexibility so as not to impair the flexibility of the original plate for a flexographic printing plate while exhibiting the function of ensuring sufficient adhesion to the substrate.
In this embodiment, the intermediate layer (C) contains water-dispersible latex and water-soluble polyurethane.

The water-dispersible latex contained in the intermediate layer (C) provides good adhesion between the intermediate layer (C) and the photosensitive resin composition layer (B), and between the intermediate layer (C) and the ablation layer (D) described later. It has a function to make
By providing the intermediate layer (C), the adhesion between the intermediate layer (C) and the photosensitive resin composition layer (B) and between the intermediate layer (C) and the ablation layer (D) can be improved, In the flexographic printing plate precursor, it is possible to prevent the ablation layer (D) from being broken or scratched when the cover sheet (E) laminated on the ablation layer (D) is peeled off from the ablation layer (D). .

Examples of the water-dispersible latex contained in the intermediate layer (C) include, but are not limited to, polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex. , water-dispersible latex polymers such as polychloroprene latex, polyisoprene latex, polyurethane latex, methyl methacrylate-butadiene copolymer latex, vinylpyridine polymer latex, butyl polymer latex, thiocol polymer latex, acrylate polymer latex, Polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid are included.
Among these, a water-dispersible latex polymer containing a butadiene skeleton or an isoprene skeleton in the molecular chain is preferable 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 water-dispersible latex contained in the intermediate layer (C) constituting the flexographic printing plate precursor of the present embodiment has a polar group, and the polar group includes a carboxyl group, an amino group, and a hydroxyl group. , phosphate groups, sulfonic acid groups, salts thereof, and the like are preferred.

In the flexographic printing plate using the flexographic printing plate precursor of the present embodiment, from the viewpoint of obtaining high washability and excellent adhesion between layers, the water-dispersible latex should have a carboxyl group or a hydroxyl group. is preferred.
These water-dispersible latexes containing polar groups may be used singly or in combination of two or more.

Examples of the water-dispersible latex having a carboxyl group include those containing a carboxyl group-unsaturated monomer as a polymerization monomer. Examples of the unsaturated monomer having a carboxyl group include monobasic acid monomers. and dibasic acid monomers.
Monobasic acid monomers include, for example, acrylic acid, methacrylic acid, crotonic acid, vinylbenzoic acid, cinnamic acid, and sodium salts, potassium salts, and ammonium salts of these monobasic acid monomers.
Dibasic acid monomers include, for example, itaconic acid, fumaric acid, maleic acid, citraconic acid, muconic acid, and sodium salts, potassium salts, and ammonium salts of these dibasic acid monomers.
In this embodiment, only one type of unsaturated monomer having a carboxyl group may be used alone, or a plurality of types of unsaturated monomers having a carboxyl group may be used simultaneously.

Examples of the water-dispersible latex having a hydroxyl group include, but are not limited to, ethylene-based monocarboxylic acid alkyl ester monomers, but examples include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylic 2-hydroxypropyl acid, 2-hydroxypropyl methacrylate, 1-hydroxypropyl acrylate, 1-hydroxypropyl methacrylate, hydroxycyclohexyl (meth)acrylate and the like.

The content of the water-dispersible latex in the intermediate layer (C) is preferably 3% by mass or more, more preferably 10% by mass or more, more preferably 20% by mass, based on the total amount of the intermediate layer (C) from the viewpoint of resin adhesion. The above is more preferable.
From the viewpoint of suppressing stickiness, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.
When the content of the water-dispersible latex in the intermediate layer (C) is 3% by mass or more, sufficient adhesion can be obtained, and when the content is 90% by mass or less, sufficient film strength can be obtained. A flexographic printing plate precursor with less tack can be obtained.

The toluene gel fraction of the water-dispersible latex is preferably 70% by mass or more and 90% by mass or less. It is more preferably 70% by mass or more and 85% by mass or less, and still more preferably 70% by mass or more and 80% by mass or less.
When the toluene gel fraction of the water-dispersible latex is in the range of 70% by mass or more and 90% by mass or less, a flexographic printing plate precursor with little stickiness can be obtained while maintaining sufficient rubber elasticity and film strength.

Here, the toluene gel fraction of water-dispersible latex can be measured by the following method.
After emulsion polymerization of the water-dispersible latex, 0.5 g of the film obtained by drying the dispersion after emulsion polymerization at 130°C for 30 minutes was taken, immersed in 30 mL of toluene at 25°C, and shaken for 3 hours using a shaker. After filtering through a 320 SUS mesh and drying the non-passing portion at 130° C. for 1 hour, the mass X (g) is measured.
The gel fraction is calculated from the following formula.
Gel fraction (% by mass) = X (g)/0.5 (g) x 100
The toluene gel fraction of the water-dispersible latex can be controlled within the above numerical range by adjusting the polymerization temperature, monomer composition, amount of chain transfer agent, and particle size.

The water-soluble polyurethane contained in the intermediate layer (C) 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 water-soluble 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 polyisocyanate.

Examples of the polyol compound include, but are not limited to, polyether polyol, polyester polyol, polycarbonate diol, and polyacryl polyol.
These may be used individually by 1 type, and may be used in combination of 2 or more types.
Among these, polyether polyol is preferable from the viewpoint of adhesion.
Examples of polyether polyols include polyether polyols obtained by ring-opening copolymerization of polyhydric alcohols with ionically polymerizable cyclic compounds, that is, reaction products of polyhydric alcohols and ionically polymerizable cyclic compounds.

Examples of the polyhydric alcohol include, but are not limited to, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, and polydecamethylene glycol. , glycerin, trimethylolpropane, pentaerythritol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, hydroquinone, naphthohydroquinone, anthrahydroquinone, 1,4-cyclohexanediol, tricyclodecanediol, tricyclodecanediol Examples include methanol, pentacyclopentadecanediol, and pentacyclopentadecanedimethanol.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of the ionically polymerizable cyclic compound include, but are not limited to, ethylene oxide, propylene oxide, 1,2-butylene oxide, butene-1-oxide, isobutene oxide, and 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 monoxide, isoprene monoxide, vinyl oxetane, vinyl Cyclic ethers such as tetrahydrofuran, vinylcyclohexene oxide, phenylglycidyl ether, butylglycidyl ether, glycidyl benzoate and the like can be mentioned.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

As the polyol compound, ring-opening copolymerization of the ionically polymerizable cyclic compound and cyclic imines such as ethyleneimine, cyclic lactone acids such as β-propiolactone and glycolic acid lactide, or dimethylcyclopolysiloxanes is performed. It is also possible to use polyether polyols.
The ring-opening copolymers of these ionically polymerizable cyclic compounds may be randomly bonded or may be bonded in blocks.

As the polyisocyanate, any polyisocyanate that is generally used in the production of polyurethane can be used without particular limitation.
Examples of polyisocyanates include, but are not limited to, 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, tetramethyl xylylene diisocyanate, 2,5 (or 6)-bis(isocyanatomethyl)-bicyclo[2.2 .1] heptane and the like.
These polyisocyanates may be used alone or in combination of two or more.

The water-soluble polyurethane contained in the intermediate layer (C) prevents pinholes in the ablation layer (D) of the flexographic printing plate precursor during thermal extrusion molding in the manufacturing process of the flexographic printing plate precursor of the present embodiment. In order to increase the flexibility and maintain the flexibility of the flexographic printing plate precursor, the elongation of the film made of the water-soluble polyurethane is preferably 300% or more, more preferably 600% or more.

Further, the heat softening temperature of the water-soluble polyurethane is preferably 80°C to 210°C. From the viewpoint of pinhole resistance, the temperature is preferably 80° C. or higher, and from the viewpoint of pinhole resistance and adhesion, it is preferably 210° C. or lower.
Further, it is more preferably 110°C to 180°C, and even more preferably 120°C to 170°C.
The heat softening temperature of the water-soluble polyurethane can be measured with a Koka flow tester.
Further, the heat softening temperature of the water-soluble polyurethane can be controlled within the above numerical range by adjusting the type and combination of the diol component and the diisocyanate component that constitute the water-soluble polyurethane.
The characteristics that affect the pinhole resistance (PH resistance) of the ablation layer (D) are the three parameters of the heat melting temperature, elongation, and breaking strength of the water-soluble polyurethane single film contained in the intermediate layer (C). is.
During the production of the flexographic printing plate precursor, the temperature of the extrusion resin (the material of the photosensitive resin composition layer) after kneading is about 120 to 140.degree. At this time, the closer or lower the thermal softening temperature of the water-soluble polyurethane film contained in the intermediate layer (C) to the extruded resin temperature after kneading, the higher the elongation of the water-soluble polyurethane film. The more the resin is kneaded, the more it follows the shear stress of the extruded resin, so that the ablation layer and the intermediate layer are easily formed into a sheet.
In addition, the breaking strength of the water-soluble polyurethane single film is measured when thermal lamination of the kneaded resin (including gel-like substances that are poorly kneaded), which is the material constituting the photosensitive resin composition layer, the ablation layer, and the intermediate layer. The intermediate layer in direct contact with the kneaded resin is broken by scratching by the gel-like substance, and pinholes are generated in the ablation layer (D).

The number average molecular weight of the water-soluble polyurethane is preferably 1,000 to 200,000, more preferably 30,000 to 100,000, from the viewpoint of flexibility.

From the viewpoint of adhesion, the water-soluble polyurethane contained in the intermediate layer (C) is preferably polyether polyurethane obtained by reacting polyether polyol and isocyanate. As such polyether polyurethane, for example, Superflex 300 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Hydran WLS202 (manufactured by DIC Corporation), and the like are commercially available.

The water-soluble polyurethane preferably has a polyether, polyester, polycarbonate, or polyester ether structure in the molecule, more preferably polyether, polyester, or polycarbonate, and further has a polyether structure from the viewpoint of adhesiveness. is preferred.

Resin adhesion, that is, adhesion between the intermediate layer (C) and the photosensitive resin composition layer (B) is expressed by the water-dispersible latex and water-soluble polyurethane contained in the intermediate layer (C).
Regarding the initial adhesion, the water-soluble polyurethane mainly contributes to the resin adhesion, and the lower the Tg of the water-soluble polyurethane, the easier it is to wet with the photosensitive resin composition layer, so the resin adhesion is excellent. There is a tendency.
In addition, the anchoring effect of the water-dispersible latex contributes to the adhesion after the flexographic printing plate precursor has been left for a long period of time.
Since the styrene-butadiene-based resin in the photosensitive resin composition layer is easily compatible with the water-dispersible latex in the intermediate layer (C), it migrates during long-term storage and exhibits an anchoring effect. Adhesion is maintained.

The content of the water-soluble polyurethane in the intermediate layer (C) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, relative to the total amount of the intermediate layer (C).
Moreover, it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.
A water-soluble polyurethane content of 10% by mass or more relative to the total amount of the intermediate layer (C) provides sufficient pinhole resistance, and a content of 90% by mass or less provides sufficient adhesion. You get sex.

The water-soluble polyurethane preferably has a polar group from the viewpoint of washability and strength of the intermediate layer (C) at high temperatures.
Examples of polar groups include, but are not limited to, polyether groups such as hydroxy groups, alkoxy groups, ethylene oxide groups, and propylene oxide groups; carbonyl groups, carboxyl groups, amino groups, urea groups, cyano groups, A sulfonic acid group, a phosphoric acid group, and the like can be mentioned.
Among these, water-soluble polyurethanes having carboxyl groups or hydroxyl groups are preferred.

The intermediate layer (C) may further contain a water-soluble polyamide.
The water-soluble polyamide is not particularly limited as long as it is a polymer having a polyamide bond.
As the polymer having a polyamide bond, conventionally known soluble synthetic high molecular compounds can be used. -113537, etc.), tertiary nitrogen-containing polyamide (see, for example, JP-A-50-76055), ammonium salt-type tertiary nitrogen atom-containing polyamide (eg, JP-A-53-36555, etc.) See), an addition polymer of an amide compound having at least one amide bond and an organic diisocyanate compound (see, for example, JP-A-58-140737), an addition polymer of a diamine having no amide bond and an organic diisocyanate compound ( For example, see JP-A-4-97154).
These water-soluble polyamides may be used alone or in combination of two or more.
Among them, a tertiary nitrogen atom-containing polyamide and an ammonium salt type tertiary nitrogen atom-containing polyamide are preferably used because they can impart an appropriate hardness to the intermediate layer (C).

The content of the water-soluble polyamide in the intermediate layer (C) is 10 to 700 parts by mass, preferably 15 to 600 parts by mass, preferably 20 to 500 parts by mass, based on 100 parts by mass of the water-dispersible latex. Parts by mass are more preferred.
When the content of the water-soluble polyamide is 10 parts by mass or more, the film strength of the intermediate layer can be maintained, and sufficient pinhole resistance can be obtained.
Moreover, resin adhesiveness can be maintained by the content rate of water-soluble polyamide being 700 mass parts or less.

(Other form of original plate for flexographic printing plate)
In the present embodiment, the support (A), the photosensitive resin composition layer (B), the intermediate layer (C), and the ablation layer (D) are provided in the order described above, and the intermediate layer Another preferred embodiment is a flexographic printing plate precursor in which (C) contains a polyamide copolymer having a monomer unit containing a basic nitrogen atom and an alkylene glycol structural unit.
In the flexographic printing plate precursor of such a configuration, since the intermediate layer (C) effectively prevents oxygen from entering the photosensitive resin composition layer (B), the polymerization is not hindered by oxygen, and Since the haze of the intermediate layer (C) is low, excellent image reproducibility is obtained.

The polyamide copolymer contained in the intermediate layer (C) includes a monomer having a basic nitrogen, a monomer having an alkylene glycol structure shown below, and other monomers such as dicarboxylic acid. can be obtained by performing condensation polymerization, polyaddition reaction, or the like.
A polyamide copolymer containing a monomer unit containing a basic nitrogen atom in the molecule is a polyamide copolymer having a monomer unit containing a basic nitrogen atom in a portion of the main chain or side chain in addition to the amide group. As such a polyamide copolymer, a polyamide having a tertiary nitrogen atom in the main chain is preferred.
The basic nitrogen is preferably piperazine or an N,N-dialkylamino group, more preferably piperazine.

Basic nitrogen-containing monomers used to obtain these polyamide copolymers include, for example, N,N'-bis(aminomethyl)-piperazine, N,N'-bis(β-aminoethyl)-piperazine , N,N′-bis(γ-aminobenzyl)-piperazine, N-(β-aminoethyl)piperazine, N-(β-aminopropyl)piperazine, N-(ω-aminohexyl)piperazine, N-(β -aminoethyl)-2,5-dimethylpiperazine, N,N-bis(β-aminoethyl)-benzylamine, N,N-bis(γ-aminopropyl)-amine, N,N'-dimethyl-N, Diamines such as N'-bis(γ-aminopropyl)-ethylenediamine, N,N'-dimethyl-N,N'-bis(γ-aminopropyl)-tetramethylenediamine; N,N'-bis(carboxymethyl )-piperazine, N,N'-bis(carboxymethyl)-methylpiperazine, N,N'-bis(carboxymethyl)-2,6-dimethylpiperazine, N,N'-bis(β-carboxyethyl)-piperazine , N,N-bis(carboxymethyl)-methylamine, N,N-bis(β-carboxyethyl)-ethylamine, N,N-bis(β-carboxyethyl)-methylamine, N,N-di(β -carboxyethyl)-isopropylamine, N,N'-dimethyl-N,N'-bis-(carboxymethyl)-ethylenediamine, N,N'-dimethyl-N,N'-bis-(β-carboxyethyl)- Dicarboxylic acids such as ethylenediamine, or lower alkyl esters thereof; acid halides, N-(aminomethyl)-N'-(carboxymethyl)-piperazine, N-(aminomethyl)-N'-(β-carboxyethyl) -piperazine, N-(β-aminoethyl)-N′-(β-carboxyethyl)-piperazine, N-carboxymethylpiperazine, N-(β-carboxyethyl)piperazine, N-(γ-carboxyhexyl)piperazine, N-(ω-carboxyhexyl)piperazine, N-(aminomer)-N-(carboxymethyl)-methylamine, N-(β-aminoethyl)-N-(β-carboxyethyl)-methylamine, N-( ω-amino acids such as aminomethyl)-N-(β-carboxyethyl)-isopropylamine, N,N'-dimethyl-N-(aminomethyl)-N'-(carboxymethyl)-ethylenediamine, and the like.

As the monomer having an alkylene glycol structural unit in the molecule, which is used to obtain the polyamide copolymer, those derived from a polyethylene glycol or polypropylene glycol structure are preferable. derived is preferred.
In order to incorporate the polyalkylene component into the polyamide copolymer, it is preferable to use polyalkylene glycol modified at both ends with diamine or dicarboxylic acid. Examples of polyalkylene glycol modified at both ends with diamine include bisaminopropyl polyethylene glycol, and examples of polyalkylene glycol modified at both ends with dicarboxylic acid include biscarboxypolyethylene glycol. be done.
In this case, the number average molecular weight of the alkylene glycol structural unit is not particularly limited, but is preferably 400 to 4000 from the viewpoint of water solubility.

These basic nitrogen-containing monomer components are preferably 10 to 100 mol%, preferably 10 to 80 mol, with respect to the sum of the total constituent components of the polyamide copolymer, that is, the dicarboxylic acid unit and the diamine structural unit. % is more preferable. Within this range, the intermediate layer (C) in the flexographic printing plate precursor of the other embodiment can be made excellent in water washability and film strength.

Further, the polyamide copolymer is obtained by polymerizing each component of the polyamide copolymer alone and blending, that is, the monomer having a basic nitrogen and the monomer having an alkylene glycol structure are separately added to dicarboxylic acid. Compared to the case of blending polyamide obtained by condensation polymerization and polyaddition reaction with acid monomers, it does not form a sea-island structure and forms a uniform layer. The haze of C) is lowered, and the blank depth of the plate after plate making can be ensured.

In the flexographic printing plate precursor of the other embodiment described above, the content of the polyamide copolymer in the intermediate layer (C) is such that migration of monomers from the photosensitive resin composition layer (B) to the ablation layer (D) From the viewpoint of preventing this, it is preferably 5 to 80% by mass based on the total amount of the intermediate layer (C). It is more preferably 10 to 70% by mass, still more preferably 20 to 60% by mass.
Further, within the above range, it is possible to obtain a flexographic printing plate precursor having less tackiness, excellent handleability, less susceptibility to polymerization inhibition by oxygen, and excellent image reproducibility.

In the flexographic printing plate precursor of the other embodiment described above, the intermediate layer (C) has the above-described water-dispersible latex having a polar group and a polar group in order to improve resin adhesion and pinhole resistance. It may further contain a water-soluble polyurethane.

(Other Components of Intermediate Layer (C))
The intermediate layer (C) constituting the flexographic printing plate precursor of the present embodiment contains the above-described water-soluble polyurethane, water-dispersible latex, water-soluble polyamide, and polyamide copolymers in other forms of flexographic printing plate precursors. In addition, other polymers may be used together as long as the performance is not impaired.
Other polymers include, but are not limited to, 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, polyimide, silicone rubber, butyl rubber, and isoprene rubber.
From the viewpoint of compatibility with water-soluble polyurethanes, water-dispersible latexes, water-soluble polyamides, and polyamide copolymers, it is preferable that the polymers used in combination are also water-soluble.
These polymers may be used singly or in combination.

Examples of the method for producing the intermediate layer (C) include a method of coating on the ablation layer (D).
For the purpose of uniformly applying the composition for forming the intermediate layer (C) to the ablation layer (D), in the intermediate layer (C) so that the surface energy of the ablation layer (D) is equivalent to A silicone compound or surfactant may be contained.

The silicone compound is not particularly limited in its molecular structure, but preferred compounds include compounds having polyalkylsiloxane in the main chain, such as polydimethylsiloxane and polydiethylsiloxane. Moreover, it may be a compound having a polysiloxane structure in a part of the molecule.
Furthermore, a compound in which a specific organic group is introduced into the polysiloxane structure can be used. Specifically, a compound in which an organic group is introduced into the side chain of polysiloxane, a compound in which an organic group is introduced into both ends of polysiloxane, a compound in which an organic group is introduced into one end of polysiloxane, and a side chain of polysiloxane and Examples thereof include compounds in which organic groups are introduced at both ends.
It is preferable to use a silicone compound into which a polyether is introduced from the viewpoint that migration of monomers and the like from the photosensitive resin composition layer (B) to the ablation layer (D) can be prevented.

Examples of organic groups to be introduced into the polysiloxane structure include amino groups, carboxyl groups, carbinol groups, aryl groups, alkyl groups, alkoxycarbonyl groups, alkoxy groups, and linear or branched groups substituted with at least one aryl group. alkyl groups, polyoxyalkylene groups (hereinafter also referred to as polyether groups), and the like.

Further, other components such as surfactants, antiblocking agents, release agents, UV absorbers, dyes, pigments, etc. may be added to the intermediate layer (C) within a range that does not impair the strength and flexibility. good too.

The thickness of the intermediate layer (C) is preferably 0.5 μm or more and 20 μm or less. When the thickness is 0.5 μm or more, a sufficient strength of the intermediate layer can be obtained, and when the thickness is 20 μm or less, deterioration of image formability due to scattering of light during relief exposure can be sufficiently suppressed. 0.5 μm or more and 10 μm or less is more preferable, and 0.5 μm or more and 5 μm or less is even more preferable.

Since the photosensitive resin composition layer (B) is exposed to ultraviolet light through the intermediate layer (C) during relief exposure, the intermediate layer (C) must be made of a material that transmits ultraviolet light. .
The UV transmittance of the intermediate layer (C) is preferably 40% or more at a wavelength of 365 nm. When it is 40% or more, curing of the photosensitive resin composition layer (B) is sufficiently performed, and sufficient image formation can be obtained. It is more preferably 50% or more, and even more preferably 60% or more.

(Ablation layer (D))
The ablative layer (D) of the flexographic printing plate precursor of the present embodiment preferably blocks ultraviolet light, absorbs infrared laser light during drawing, and is partially or ablated instantaneously by the heat. This enables drawing processing, and also serves as a mask image when the photosensitive resin composition layer (B) is exposed and cured. When the unexposed area of the photosensitive resin composition layer (B) is washed out after the exposure is finished, the ablation layer (D) is also removed at the same time.

The ablative layer (D) comprises at least a material having a function of blocking radiation in the ultraviolet to visible region, absorbing light in the infrared region and converting it into heat, and a function of blocking light in the ultraviolet to visible region, and the material thereof. and a binder polymer. Further, as optional components other than these, a pigment dispersant, a filler, a silicone oil, a surfactant, a coating aid, or the like can be contained within a range that does not impair the effects of the present invention.

Examples of the material having the infrared absorption function and the ultraviolet light blocking function include dyes such as phthalocyanine, substituted phthalocyanine derivatives, cyanine, merocyanine dyes, and polymethine dyes, and pigments such as carbon black, graphite, chromium oxide, and iron oxide. . Among these, carbon black is preferable from the viewpoint of light-to-heat conversion rate, economic efficiency, and handleability.
The particle size of carbon black can be selected within an arbitrary range, but in general, the smaller the particle size, the higher the sensitivity to infrared rays and the worse the dispersibility. From this point of view, the particle size of the carbon black is preferably 20 nm or more and 80 nm or less, more preferably 25 nm or more and 70 nm or less, and even more preferably 30 nm or more and 60 nm or less.

The content of carbon black in the ablative layer (D) is preferably within a range that ensures sensitivity capable of being removed by the laser beam used during drawing processing of the ablative layer (D).
The sensitivity to a laser beam increases as the amount of carbon black uniformly dispersed in the ablation layer (D) increases, but tends to decrease when the amount of carbon black becomes too large to cause aggregation or the like. From such a viewpoint, the content of carbon black in the entire ablation layer (D) is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and 30% by mass or more and 70% by mass. More preferred are:

As for the non-infrared shielding effect of the ablative layer (D), the optical density of the ablative layer (D) is preferably 2 or more, more preferably 3 or more. The optical density can be measured using a D200-II transmission densitometer (manufactured by GretagMacbeth). Further, the optical density is a so-called visual sensitivity (ISO visual), and the light to be measured has a wavelength range of about 400 to 750 nm.

The binder polymer of the ablative layer (D) is not particularly limited, but by using an acid-modified polymer, it can be rapidly dissolved or dispersed and removed by an alkaline developer described later. Furthermore, it is preferably used because it can prevent the occurrence of wrinkles due to moisture absorption.
Another method for shortening the development time of the ablative layer (D) is to make the ablative layer (D) thinner. On the other hand, in order to ensure sufficient strength of the ablation layer (D), a method of improving the development speed of the ablation layer (D) and ensuring the thickness of the ablation layer (D) is more preferable. From this point of view, the ablative layer (D) is required to have the property of being sparingly soluble or insoluble in neutral water and soluble or dispersible in alkaline water.

Moreover, from the viewpoint of suppressing the occurrence of wrinkles due to moisture absorption, the acid-modified polymer is preferably water-insoluble.
The term "water-insoluble" refers to the property that 100 mL or more of water is required to dissolve 1 g of the substance.

Examples of the acidic group of the acid-modified polymer include, but are not limited to, a carboxyl group, a sulfonic acid group, a phosphoric acid group, and the like. Among these, a carboxyl group is preferable from the viewpoint of low hygroscopicity and ease of synthesis and availability.

The polymer for the acid-modified polymer contained in the ablation layer (D) is not limited to the following, but examples include acrylic resins, styrene resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, Resins, polyamide resins, polyacetal resins, polycarbonate resins, polyester resins, polyphenylene sulfide resins, polysulfone resins, polyether ketone resins, polyimide resins, fluorine resins, silicone resins, urethane resins, urea resins, melamine-based resins, guanamine-based resins, epoxy-based resins, phenol-based resins, and copolymers of these resins.
These polymers may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these polymers, acrylic resins, polyolefin resins, polyamide resins, polyacetal resins, polycarbonate resins, polyether ketone resins, and polyimide resins are preferred from the viewpoint of ease of modification by acidic groups and suppression of wrinkles due to moisture absorption. A resin is preferred, and an acrylic resin is particularly preferred.

Any component other than the acid-modified polymer and carbon black can be added to the ablative layer (D) without departing from the object of the present invention.
From the viewpoints of suppressing wrinkles due to moisture absorption of the ablation layer (D), improving hardness, and improving adhesion between the ablation layer (D) and the intermediate layer (C), it is possible to add a polymer different from the acid-modified polymer. preferable.
From this point of view, the other type of polymer includes a copolymer composed of a copolymer of a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer, a hydrogenated product of the copolymer, and a copolymer of the copolymer Modified products are preferred.
The ratio of the monovinyl-substituted aromatic hydrocarbon monomer and the conjugated diene monomer can be set arbitrarily. In general, the higher the ratio of the monovinyl-substituted aromatic hydrocarbon monomer, the more effective it is in improving the hardness, and the higher the ratio of the conjugated diene monomer, the more effective it is in improving the flexibility. From this point of view, the proportion of the monovinyl-substituted aromatic hydrocarbon monomer is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less.
Specific examples include styrene-butadiene copolymers, styrene-butadiene-styrene copolymers, styrene-ethylene-butadiene-styrene copolymers, styrene-isoprene copolymers, styrene-isoprene-styrene copolymers, and the like. be done.
The copolymer may be an alternating copolymer, a random copolymer, a block copolymer, or a graft copolymer.
Examples of modifiers include modification with amine maleic anhydride.
These polymers may be used singly or in combination of two or more.
The amount of these polymers added is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more in the ablation layer from the viewpoint of manifesting the physical properties described above.
In addition, from the viewpoint of sufficiently ensuring the addition ratio of carbon black and acid-modified polymer, it is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

(Cover sheet (E))
In the flexographic printing plate precursor of the present embodiment, a cover sheet (E) is laminated on the ablation layer (D) from the viewpoint of protecting the ablation layer (D) and improving the handleability of the flexographic printing plate precursor. preferably.
Examples of the cover sheet (E) used in the flexographic printing plate precursor of the present embodiment include, but are not limited to, polyester films such as polypropylene film, polyethylene film, polyethylene terephthalate, and polyethylene naphthalate; film; and the like.
Among these, a dimensionally stable polyester film having a thickness in the range of 75 to 300 μm is preferred.

[Method for producing flexographic printing plate precursor]
The flexographic printing plate precursor of this embodiment can be produced by a production method including the following steps.
Laminating an adhesive layer on the support (A);
lamination of the ablative layer (D) on the cover sheet (E);
Laminating the intermediate layer (C) on the ablative layer (D) of the cover sheet (E) laminated with the ablative layer (D);
A photosensitive resin composition layer (B) is laminated on the adhesive layer so that the intermediate layer (C) laminated on the cover sheet (E) faces the photosensitive resin composition layer (B). a step of sandwiching the photosensitive resin composition layer (B) between a support (A) and a cover sheet;

In the step of laminating the adhesive layer on the support (A), the material for forming the adhesive layer is applied to the support (A) 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 coating workability, and is a solution dissolved in an organic solvent having a solid content of 5 to 40%. is more preferable. A support (A) having an adhesive layer can be obtained by drying after coating the material for forming the adhesive layer.

In the step of laminating the ablative layer (D) on the cover sheet (E), the material for forming the ablative layer (D) is applied to the cover sheet (E) with a knife coater or the like.
From the viewpoint of coating workability, the material for forming the ablative layer (D) is preferably a solution dissolved in an organic solvent such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, etc., and the solid content is 5 to 5. More preferably it is a 30% solution in an organic solvent.
A cover sheet (E) having an ablative layer (D) can be obtained by applying a material for forming the ablative layer (D) and drying it.

In the step of laminating the intermediate layer (C) on the ablative layer (D) of the cover sheet (E) laminated with the ablative layer (D), the material constituting the intermediate layer (C) is added to the ablative layer ( D) is applied to the ablation layer (D) side of the cover sheet (E) with a knife coater or the like.
A cover sheet (E) having an intermediate layer (C) and an ablation layer (D) can be obtained by applying a material that constitutes the intermediate layer (C) and then drying it.

In the step of sandwiching the photosensitive resin composition layer (B) between the support (A) and the cover sheet (E), the support (A) having the adhesive layer (B), the intermediate layer (C) and the ablation layer a cover sheet (E) having (D), and a photosensitive resin composition layer (B) such that the adhesive layer and the intermediate layer (C) face the photosensitive resin composition layer (B); It is sandwiched between the support (A) and the cover sheet (E), heated, and compression-molded to obtain a flexographic printing plate precursor.

[Method for producing flexographic printing plate]
A method for producing a flexographic printing plate using the flexographic printing plate precursor of the present embodiment includes a support (A) and a photosensitive resin composition layer (B) provided on the support (A). , for a flexographic printing plate comprising an intermediate layer (C) provided on the photosensitive resin composition layer (B) and an ablation layer (D) provided on the intermediate layer (C) In the step of irradiating the original plate with ultraviolet rays from the support (A) side and in the step of irradiating ultraviolet rays after the ablation layer (D) is irradiated with infrared rays to draw a pattern, the intermediate layer (C) is passed through The photosensitive resin composition layer (B) is irradiated with ultraviolet rays, and the ablation layer (D), the intermediate layer (C), and the unexposed photosensitive resin composition layer (B) are removed with the alkaline developer. .
Thereafter, a step of post-exposure treatment is performed as necessary to obtain a plate (flexographic printing plate) of the cured product of the photosensitive resin composition layer (B).
From the viewpoint of imparting releasability, the surface of the printing plate may be brought into contact with a liquid containing a silicone compound and/or a fluorine compound.

The step of irradiating ultraviolet rays from the support (A) side can be carried out using a conventional irradiation unit.
As ultraviolet rays, ultraviolet rays with a wavelength of 150 to 500 nm can be used, and ultraviolet rays with a wavelength of 300 to 400 nm can be preferably used.
As the light source, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, an extra-high pressure mercury lamp, a metal halide lamp, a xenon lamp, a zirconium lamp, a carbon arc lamp, an ultraviolet fluorescent lamp, or the like can be used.
The step of irradiating with ultraviolet rays may be performed before the step of drawing a pattern on the ablation layer (D), or may be performed after the step of drawing a pattern.
When the flexographic printing plate precursor has a cover film (E), the cover film (E) is first peeled off. Thereafter, the ablation layer (D) is pattern-irradiated with infrared rays to form a mask on the photosensitive resin composition layer (B). Examples of suitable infrared lasers include ND/YAG lasers (eg 1064 nm) or diode lasers (eg 830 nm).
Suitable laser systems for CTP plate making technology are commercially available, for example the diode laser system CDI Spark (ESKO GRAPHICS) can be used.
This laser system includes a rotating cylindrical drum that holds a flexographic printing plate precursor, an IR laser irradiation device, and a layout computer, and image information is transmitted directly from the layout computer to the laser device.
As described above, after the pattern is drawn, the entire surface of the photosensitive resin composition layer (B) is irradiated with ultraviolet rays through a mask. This can be done with the plate mounted on the laser cylinder, but generally the plate is removed from the laser system and irradiated using a conventional irradiation unit. As the irradiation unit, the same unit as used for ultraviolet irradiation from the support (A) side can be used.
In the case where the intermediate layer (C) of the flexographic printing plate precursor of the present embodiment absorbs a large amount of ultraviolet rays and cannot be ignored in the pattern exposure step, the amount of ultraviolet rays absorbed by the intermediate layer (C) is taken into consideration in advance and the ultraviolet rays are appropriately absorbed. It is preferable to adjust the irradiation amount.

Next, a developing process is performed.
A conventionally known method can be applied to the developing step.
Specifically, the photosensitive resin composition layer (B) is exposed as described above, then immersed in a developing solution, and the unexposed portions are dissolved or scraped off with a brush or the like, or the developing solution is applied to the plate surface by spraying or the like. and then dissolving or scraping off the unexposed portions with a brush or the like.

When the unexposed area is developed with a solvent, the developing solvent is not particularly limited, but examples include esters such as heptyl acetate and 3-methoxybutyl acetate; hydrocarbons such as petroleum fractions, toluene and decalin; and tetrachlorethylene. alcohols such as propanol, butanol and pentanol mixed with chlorine-based organic solvents; water; ethers such as polyoxyalkylene alkyl ether;

When the unexposed area is developed with a water-based developer, the water-based developer is a developer containing water as a main component, and may be water itself. agent, and, if necessary, a pH adjuster, a cleaning aid, etc. may be blended.

Examples of nonionic surfactants include, but are not limited to, polyoxyalkylene alkyl or alkenyl ethers, polyoxyalkylene alkyl or alkenyl phenyl ethers, polyoxyalkylene alkyl or alkenylamines, polyoxyalkylene alkyl or alkenyl amides, ethylene oxide/ A propylene oxide block additive and the like can be mentioned.

Examples of anionic surfactants include, but are not limited to, linear alkylbenzene sulfonates having an average carbon number of 8 to 16 alkyl, α-olefin sulfonates having an average carbon number of 10 to 20, alkyl groups or alkenyl dialkyl sulfosuccinates having 4 to 10 carbon atoms in the group, sulfonates of fatty acid lower alkyl esters, alkyl sulfates having an average carbon number of 10 to 20, linear or branched alkyl groups having an average carbon number of 10 to 20, or Alkenyl group-containing alkyl ether sulfates added with an average of 0.5 to 8 mol of ethylene oxide, saturated or unsaturated fatty acid salts having an average of 10 to 22 carbon atoms, and the like.

The pH adjuster is not particularly limited, but examples thereof include sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, and sodium acetate. Among the above, sodium silicate is preferable because it is easily dissolved in water.

Furthermore, a cleaning aid may be added to the developer. The "cleaning aid" means a substance that enhances the cleaning (developing) ability of a developer by using the surfactant and the pH adjuster in combination. Examples of cleaning aids include amines such as monoethanolamine, diethanolamine and triethanolamine, ammonium salts such as tetramethylammonium hydroxide, and paraffin hydrocarbons.

One or more selected from the group consisting of surfactants such as nonionic and anionic surfactants, pH adjusters, and cleaning aids is added to the developer in an amount of 0.1 to 50% by mass, preferably 1 to 10%. It can be used by adding and mixing in the range of % by mass.

During development, the printing original plate may be supplementarily vibrated with ultrasonic waves or the like, the surface of the printing original plate may be rubbed with a mechanical means such as a brush, or the developer may be sprayed from a nozzle.

From the viewpoint of obtaining a flexographic printing plate which can obtain bright printing in a solvent-based and/or water-based developer and has excellent ink entanglement and ink transfer properties, 0.01% to 5% of a silicone component is added. may
As the silicone component, the same silicone compound as in the intermediate layer (C) can be used. Among silicone compounds, silicone oils modified with amino groups, polyether groups, carbinol groups, etc. are preferred as the silicone component to be contained in the developer.

Post-processing exposure includes a method of irradiating the surface with light having a wavelength of 300 nm or less. If necessary, light with a wavelength longer than 300 nm may be used together.

EXAMPLES The present invention will be described below with specific examples and comparative examples, but the present invention is not limited to these.

[(1) Measurement methods and evaluation methods used in Examples and Comparative Examples]
((a) Evaluation of resin adhesion)
The flexographic printing plate precursors produced in Examples and Comparative Examples were cut into a size of 2.54 cm×10 cm. This is called a "photosensitive resin construction".
After peeling off the cover sheet of the photosensitive resin structure, two lines of adhesive tape (Cellotape (registered trademark) CT-15 manufactured by Nichiban Co., Ltd., width 15 mm) were pasted on the ablation layer so as to overlap each other by about 5 mm. After that, the adhesive tape was peeled off in the direction in which the ablation layer and the photosensitive resin composition layer were peeled off.
The tensile strength at this time was measured and defined as "resin adhesion".
Initial adhesion to resin was measured and evaluated according to the following criteria.
Also, the photosensitive resin structure was placed in a constant temperature bath at 40° C. and 80% humidity, and the same measurement and evaluation were performed after one month.
<Evaluation Criteria for Resin Adhesion>
◎: Breakage of the photosensitive resin composition layer ○: Breakage of the photosensitive resin composition layer did not occur, but the tensile strength was 100 g / inch or more ×: Breakage of the photosensitive resin composition layer and a tensile strength of less than 100 g/inch. In the tensile strength measurement test, the adhesive tape side was peeled off in the direction of 180 °, and an Autograph AGS-100G (manufactured by Shimadzu Corporation) was used to measure the cross head. It was measured at a speed of 50 mm/min.

((b) Evaluation of pinhole resistance (PH resistance))
The flexographic printing plate precursors produced in Examples and Comparative Examples were cut into 5 pieces each having a size of 10 cm×10 cm. This is called a "sample".
In these samples, after removing the cover sheet of the ablation layer, they were placed on a light table and examined under a microscope.
In the ablation layer, the number of pinholes with a length of 20 μm or more was counted, the average value was calculated, and the value (number/m ² ) was calculated, and evaluated according to the following 1 to 5.
In the following evaluation, if it is 0 or more, it can be used practically without any problem.
<Evaluation Criteria for Pinhole Resistance>
A: The average number of pinholes is less than 2 (pieces/m ² ).
◯: The average number of pinholes is 2 (pieces/m ² ) or more and less than 5 (pieces/m ² ).
Δ: The average number of pinholes is 5 (pieces/m ² ) or more and less than 10 (pieces/m ² ).
x: The number of pinholes is an average of 10 (pieces/m ² ) or more.

((c) Evaluation of stickiness)
The flexographic printing plate precursors produced in Examples and Comparative Examples were cut into a size of 2 cm×10 cm. This is called a "sample".
In this sample, the cover sheet of the ablation layer was peeled off, and a PICMATACK tester (trademark registration No. 5857095, Toyo Seiki Co., Ltd.) was used as a measuring device to move a probe with a diameter of 5 mm and the surface of the ablation layer at a speed of 10 mm/min. 4 seconds, the tackiness (stickiness) was measured by peeling the probe vertically from the surface of the ablation layer at a speed of 10 mm/min, and evaluated according to the following criteria.
<Evaluation Criteria for Stickiness>
◎: Tack force of 1 N or less ○: Tack force of greater than 1 N to 2 N or less ×: Tack force of greater than 2 N

[(2) Method for producing laminate of support (A) and photosensitive resin composition layer (B) used in Examples and Comparative Examples]
A support (A) was produced by the following procedure.
624 g of neopentyl glycol, 93 g of ethylene glycol, 485 g of sebacic acid, and 382 g of isophthalic acid were subjected to a condensation reaction in an air atmosphere at a reaction temperature of 180° C. under a reduced pressure of 10 mmHg for 6 hours.
After that, 87 g of tolylene diisocyanate was added and further reacted at 80° C. for 5 hours to obtain a polyol.
When the number average molecular weight of the polyol thus obtained was measured by gel permeation chromatography, it was about 32,000 in terms of polystyrene.
Next, the polyol: 100 parts by mass, 2-hydroxypropyl methacrylate: 2 parts by mass, tolylene diisocyanate (3 mol) adduct of trimethylolpropane (1 mol): 17 parts by mass, "Balifast Yellow" (Oriental Kasei (trade name): 5 parts by mass and ethyl acetate: 300 parts by mass were mixed to obtain a uniform solution.
Next, the above solution was coated on a 125 μm-thick PET film “A4100” (manufactured by Toyobo Co., Ltd., trade name) using a knife coater so that the coating amount after drying was 10 to 14 g/m ² . was applied.
This was dried at 80° C. for 2 minutes and then allowed to stand in an atmosphere of 40° C. for 3 days to obtain a support (A) having a urethane-based adhesive layer.
Next, a method for producing a laminate of the support (A) and the photosensitive resin composition layer (B) is shown below.
The photosensitive resin composition produced in <Production Example 2>, which will be described later, is subjected to a heat press at 120° C. to obtain the support (A) and an anti-tack film (a PET film coated with a silicone-based release material). and heat-pressed to form a thickness of 1 mm, and a laminate of the support (A), the photosensitive resin composition layer (B) and the anti-adhesion film (hereinafter, laminate 1 and described.) was obtained.

[Examples 1 to 13], [Comparative Examples 1 to 4]
In Examples and Comparative Examples, flexographic printing plate precursors were produced.

(Example 1)
<Production Example 1: Synthesis of hydrophilic copolymer (B-1) to be contained in photosensitive resin composition layer>
125 parts by mass of water and (α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly(oxy) as a reactive emulsifier are placed in a pressure-resistant reaction vessel equipped with a stirring device and a temperature control jacket -1,2-ethanediyl) ammonium salt "Adekari Soap SE1025" (manufactured by Asahi Denka Kogyo Co., Ltd.) and 2 parts by mass were initially charged, and the internal temperature was raised to 80 ° C., 10 parts by mass of styrene and 60 parts by mass of butadiene. , 23 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, and 2 parts by mass of acrylic acid, and an oily mixture of 2 parts by mass of t-dodecylmercaptan, 28 parts by mass of water, and sodium peroxodisulfate. 1.2 parts by mass, 0.2 parts by mass of sodium hydroxide, ammonium salt of (α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly(oxy-1,2-ethanediyl) An aqueous solution consisting of 2 parts by weight was added at a constant flow rate over 5 hours and 6 hours, respectively.
The temperature of 80° C. was then maintained for 1 hour to complete the polymerization reaction and form a copolymer latex, followed by cooling.
Furthermore, after adjusting the pH of the produced copolymer latex to 7 with sodium hydroxide, unreacted monomers are removed by a steam stripping method, filtered through a 200-mesh wire mesh, and finally, the filtrate is was adjusted to have a solid content concentration of 40% by mass to obtain an aqueous dispersion of a hydrophilic copolymer (B-1) to be contained in a photosensitive resin composition layer described later.

<Production Example 2: Synthesis of photosensitive resin composition constituting photosensitive resin composition layer (B)>
110 parts by mass of the hydrophilic copolymer (B-1) produced in <Production Example 1> and 75 parts by mass of elastomer: styrene-butadiene-styrene block copolymer [D-KX405: manufactured by Kraton] were pressurized. After mixing using a kneader at 140 ° C., liquid polybutadiene [LBR-352 manufactured by Kuraray] 40 parts by mass, liquid carboxylic acid-modified acrylic polymer [CB-3060: manufactured by Soken Chemical] 5 parts by mass, photopolymerizable monomer: 10 parts by weight of 1,9-nonanediol diacrylate, 10 parts by weight of 1,6-hexanediol dimethacrylate, photopolymerization initiator: 5 parts by weight of 2,2-dimethoxyphenylacetophenone, surfactant [polyoxyethylene alkyl ether ( NT-12): Daiichi Kogyo Seiyaku Co., Ltd.] 2 parts by mass and 2,6-di-t-butyl-p-cresol 5 parts by mass were added little by little over 15 minutes, and after the addition was completed and further kneaded for 20 minutes to obtain a photosensitive resin composition.

<Production Example 3: Production of laminate of ablation layer (D) and cover sheet>
Carboxylic acid-modified acrylic polymer UC-3510 (manufactured by Toagosei Co., Ltd., trade name, acid value 70 mgKOH / g, glass transition temperature -50 ° C., number average molecular weight 2000) 0.5 parts by weight, carbon as an infrared absorber As a black dispersion, black dispersion (2) (manufactured by Showa Ink Kogyo Co., Ltd., trade name, dispersion of 40% by mass of carbon black and 7.5% by mass of dispersant) 7.3 parts by mass, styrene-butadiene - 1.3 parts by mass of Tuftec H1051 (manufactured by Asahi Kasei Co., Ltd., registered trademark, styrene content 42% by mass) as a hydrogenated styrene elastomer, and 0.3 parts by mass of KF-351 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) as a silicone resin. 4 parts by mass and 44 parts by mass of toluene were mixed to obtain a coating solution for forming an ablation layer.
This coating solution for forming the ablation layer was coated on a PET film having a thickness of about 100 μm to serve as a cover sheet so that the film thickness after drying was 3 μm, followed by drying at 90° C. for 2 minutes. , to obtain a laminate of the ablation layer and the cover sheet.

<Production of Cover Sheet Having Intermediate Layer (C) and Ablation Layer (D)>
87 parts by mass of WLS-202 (manufactured by DIC, trade name) as a water-soluble polyurethane, 3 parts by mass of XL-006 (manufactured by Asahi Kasei) as a water-dispersible latex, and KF-351A (manufactured by Shin-Etsu Chemical Co., Ltd.) as a release agent. ) was dissolved in a mixed solvent in which water and ethanol were mixed at a ratio of 75:25 to prepare a uniform solution having a solid concentration of 10%.
This solution was applied onto the ablation layer forming surface of the laminate of the ablation layer (D) and the cover sheet produced as described above using a knife coater so that the thickness after drying was 2 μm, After drying at 90° C. for 2 minutes, a cover sheet was prepared by laminating the intermediate layer (C) containing the water-soluble polyurethane and the water-dispersible latex on the ablation layer (D).

<Production of flexographic printing plate precursor having intermediate layer (C)>
Next, "Laminate 1 of Support (A) and Photosensitive Resin Composition Layer (B)" produced as described above, "Cover Sheet Having Intermediate Layer (C) and Ablation Layer (D)" was used to produce a flexographic printing plate precursor having the intermediate layer (C).
The anti-adhesion film is peeled off from the "laminate 1 of the support (A) and the photosensitive resin composition layer (B)", and the middle of the "cover sheet having the intermediate layer (C) and the ablation layer (D)". The layer (C) side was sandwiched between the support (A) and the cover sheet so as to face the photosensitive resin composition layer (B), and the whole was heated at 120° C. and compression-molded to a thickness of 1.5 mm. , to obtain a flexographic printing plate precursor.
The flexographic printing plate precursor prepared in Example 1 was flexible and exhibited good water developability.
Table 5 shows the results of pinhole resistance, resin adhesion, and stickiness.
Also, when a printing pattern was produced, excellent plate reproducibility was obtained.

(Example 2-4), (Comparative Example 1)
In <Production of cover sheet having intermediate layer (C) and ablative layer (D)> in (Example 1), the mixing ratio of water-soluble polyurethane (WLS-202) and water-dispersible latex (XL-006) was changed.
Other conditions were the same as in (Example 1) to obtain flexographic printing plate precursors having intermediate layer compositions shown in Tables 1 to 4.

(Examples 5 to 10), (Comparative Examples 2 and 3)
In (Production of cover sheet having intermediate layer (C) and ablative layer (D)) in (Example 1), the type of water-soluble polyurethane and water-dispersible latex (XL-006, manufactured by Asahi Kasei Corporation) and changed the mixing ratio of
Other conditions were the same as in (Example 1) to obtain flexographic printing plate precursors having intermediate layer compositions shown in Tables 1 to 4.

(Examples 11-13)
In (Production of cover sheet having intermediate layer (C) and ablative layer (D)) in (Example 2), part of water-soluble polyurethane was replaced with water-soluble polyamide (AQ nylon T-70 manufactured by Toray Industries, Inc.). replaced with
Other conditions were the same as in Example 2 to obtain flexographic printing plate precursors having intermediate layer compositions shown in Tables 1 to 4.

(Comparative Example 4)
In the above (production of cover sheet having intermediate layer (C) and ablative layer (D)) in (Example 2), the water-dispersible latex was changed to (LX-111NF manufactured by ZEON).
Other conditions were the same as in (Example 2) to obtain flexographic printing plate precursors having intermediate layer compositions shown in Tables 1 to 4.

Tables 5 to 8 below show the evaluation results of the properties of the flexographic printing plate precursors of Examples 1 to 13 and Comparative Examples 1 to 4.

The flexographic printing plate precursor of the present invention has industrial applicability as a flexographic printing plate precursor.

Claims (13)

a support (A);
a photosensitive resin composition layer (B);
an intermediate layer (C);
an ablation layer (D);
A flexographic printing plate precursor having, in the order,
The intermediate layer (C) contains a water-dispersible latex and a water-soluble polyurethane,
the water-dispersible latex and the water-soluble polyurethane have a polar group,
The content of the water-dispersible latex is 3% by mass or more and 80% by mass or less with respect to the total amount of the intermediate layer (C),
The content of the water-soluble polyurethane is 10% by mass or more and 87% by mass or less with respect to the total amount of the intermediate layer (C).
Original plate for flexographic printing plate. The flexographic printing plate precursor according to claim 1, wherein the water-dispersible latex has a carboxyl group or a hydroxyl group. The flexographic printing plate precursor according to claim 1 or 2, wherein the water-dispersible latex has a toluene gel fraction of 70% by mass or more and 90% by mass or less. The content ratio of the water-dispersible latex with respect to the total amount of the intermediate layer (C) is
3% by mass or more and 90% by mass or less,
The original plate for a flexographic printing plate according to any one of claims 1 to 3. The water-soluble polyurethane has a heat softening temperature of 80° C. to 210° C.
The original plate for a flexographic printing plate according to any one of claims 1 to 4. The water-soluble polyurethane has a polyether, polyester, or polycarbonate structure in its molecule,
The original plate for a flexographic printing plate according to any one of claims 1 to 5. The water-soluble polyurethane has a carboxyl group or a hydroxyl group in the molecule,
The original plate for a flexographic printing plate according to any one of claims 1 to 6. The content ratio of the water-soluble polyurethane with respect to the total amount of the intermediate layer (C) is
10% by mass or more and less than 90% by mass,
The original plate for a flexographic printing plate according to any one of claims 1 to 7. The intermediate layer (C) further contains a water-soluble polyamide,
The original plate for a flexographic printing plate according to any one of claims 1 to 8. The intermediate layer (C) is
For 100 parts by mass of the water-dispersible latex,
10 to 700 parts by mass of the water-soluble polyamide,
The original plate for a flexographic printing plate according to claim 9 . The intermediate layer (C) has a thickness of 0.5 μm or more and 20 μm or less.
The original plate for a flexographic printing plate according to any one of claims 1 to 10 . The intermediate layer (C) further contains a silicone compound,
The original plate for a flexographic printing plate according to any one of claims 1 to 11 . The ablation layer (D) is
selected from the group consisting of carbon black, an acid-modified polymer, a copolymer composed of a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer, a hydrogenated product of the copolymer, and a modified product of the copolymer; further containing at least one
The original plate for a flexographic printing plate according to any one of claims 1 to 12 .