JP2023057299A - Method for producing printing plate - Google Patents

Abstract

To provide a method for producing a printing plate that ensures stable solid print quality even after long-term storage or in the case of long-run printing.SOLUTION: A method for producing a printing plate includes an exposure step for exposing a photosensitive resin composition to light, forming a relief, and a development step for causing an unexposed photosensitive resin composition in the exposure step to be attached or adsorbed to a development medium to perform development. In the development step, the temperature of the unexposed photosensitive resin composition is controlled to be 0°C or higher and lower than 40°C.SELECTED DRAWING: None

Description

The present invention relates to a method of manufacturing a printing plate.

In recent years, flexographic printing has been widely used as a method of printing on flexible packaging such as paper and film. Plate materials for letterpress printing represented by flexographic printing include, for example, photosensitive resin plates.
Examples of methods for producing a flexographic printing plate from a photosensitive resin plate include the following methods.
First, the photosensitive resin composition layer is exposed to ultraviolet rays (referred to as back exposure) through the support to form a uniform photocurable layer. Next, relief exposure is performed from the back side (the side of the uncured photosensitive resin composition layer opposite to the side exposed to ultraviolet rays) to obtain a flexographic printing original plate. As a method of the relief exposure, there is a method of exposing to ultraviolet rays through a transparent image carrier such as a negative film that selectively transmits ultraviolet rays, or a method of ablating an image that has become digital information with an infrared laser to remove an ultraviolet-transmitting portion. and a method of exposing to ultraviolet rays through the formed thin layer. Then, the photosensitive resin composition in the unexposed portion of the original flexographic printing plate is washed away with a developer to form a relief image, thereby obtaining a flexographic printing plate.

On the other hand, due to the recent heightened awareness of environmental issues, a development step in a developing solution removal process that does not use a developing solution, that is, a dry development process, is being studied.
Among the dry development processes, the heat development method in which the flexographic printing original plate after relief exposure is heated, the unexposed areas are melted, and the melted unexposed areas are removed with a non-woven fabric or the like for development is performed without solvent. is possible and is attracting attention.

A technique related to the thermal development method is proposed in Patent Document 1, for example. This method has the advantage that no organic solvent waste or contaminated wastewater by-products are generated in the washing-out step, and no prolonged drying is required after development processing.
On the other hand, the thermal development method requires much energy for heating the original flexographic printing plate. In addition, heating tends to cause residual stress and strain inside the finally obtained flexographic printing plate. Therefore, during long-term storage or long-run printing, the residual stress and strain are relaxed, causing deformation of the surface of the flexographic printing plate, which poses a problem of unstable solid quality.
In view of such problems, in Patent Document 2, the uncured portion is heated to a sufficient temperature to soften or liquefy before development processing, and then the development medium is heated in a non-heated or low heat output state. A technique has been proposed in which development processing is performed by contacting the

Japanese Patent No. 3117749 Japanese Patent Application Laid-Open No. 2020-79926

However, in the technique proposed in Patent Document 2, it is necessary to heat to 40 ° C. or higher in order to soften or liquefy the uncured portion in the pre-development process, and the flexographic printing that is finally obtained There is still room for improvement in terms of obtaining stable solid quality over a long period of time.

Therefore, in the present invention, in view of the above-mentioned problems of the conventional technology, when dry development processing is performed, even after long-term storage and long-run printing, solid quality stability is excellent, An object of the present invention is to provide a method for manufacturing a printing plate.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, found that the above-described problems of the prior art can be solved by developing at a specific temperature in the dry development process, and completed the present invention. came to.
That is, the present invention is as follows.

[1]
An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
A method of manufacturing a printing plate, comprising
In the developing step, the temperature of the unexposed photosensitive resin composition is set to 0° C. or higher and lower than 40° C.
A method of making a printing plate.
[2]
The unexposed photosensitive resin composition contains a polymer and a liquid component that is liquid at 0 ° C. or higher and lower than 40 ° C.,
The number average molecular weight of the polymer is 3000 or more and 70000 or less,
The number average molecular weight of the liquid component is 100 or more and 1500 or less,
The method for producing a printing plate according to [1] above, wherein the content of the liquid component with respect to the total amount of the unexposed photosensitive resin composition is 8% by mass or more and 70% by mass or less.
[3]
The method for producing a printing plate as described in [2] above, wherein the polymer has an unsaturated carbon bond.
[4]
The method for producing a printing plate as described in [2] or [3] above, wherein the polymer contains a compound having a urethane structure.
[5]
The method for producing a printing plate as described in any one of [1] to [4] above, wherein the unexposed photosensitive resin composition contains an ester plasticizer.
[6]
The method for producing a printing plate as described in any one of [1] to [5] above, wherein the printing plate has a relief depth of 0.1 mm or more and 10.0 mm or less.
[7]
Any one of the above [1] to [6], comprising a step of recovering the unexposed area of the photosensitive resin composition adhered or adsorbed to the development medium as a photosensitive resin composition in the production of a new printing plate. 1. A method for producing a printing plate according to 1.
[8]
The above-mentioned [1] to [7], wherein the unexposed photosensitive resin composition adhered or adsorbed to the development medium is recovered and used as a photosensitive resin composition in the production of a new printing plate. method of making a printing plate of
[9]
An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
A method of manufacturing a printing plate having
The photosensitive resin composition used in the exposure step contains the recovered photosensitive resin composition,
The recovered photosensitive resin composition is recovered under a temperature condition of 0° C. or higher and lower than 40° C. in the developing step.
A method of making a printing plate.
[10]
a step of manufacturing a printing plate by the method for manufacturing a printing plate according to any one of [1] to [9];
a printing step of printing using the manufactured printing plate;
A printing method comprising:
[11]
An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
have
In the developing step, recovering the unexposed photosensitive resin composition at a temperature of 0° C. or more and less than 40° C.;
A method for recovering a photosensitive resin composition.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the printing plate excellent in stability of solid quality can be provided, even after long-term storage and when printing is performed in a long run.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail. It is not intended to be limited to
The present invention can be modified appropriately without departing from the gist thereof.

[Method for producing printing plate]
The printing plate manufacturing method of the present embodiment comprises an exposure step of exposing a photosensitive resin composition to form a relief, and attaching or adsorbing the unexposed photosensitive resin composition in the exposure step to a development medium. and a developing step in which the unexposed photosensitive resin composition is heated to 0° C. or higher and lower than 40° C. in the developing step.
The printing plate obtained by the production method of the present embodiment is preferably a flexographic printing plate (letterpress printing plate).

In the printing plate manufacturing method of the present embodiment, the unexposed portion of the photosensitive resin composition of the printing original plate after the exposure step is removed using a developing medium.
The unexposed areas are absorbed away by contact with the development medium.
According to the printing plate manufacturing method of the present embodiment, a printing plate having excellent solid quality stability can be obtained after long-term storage and during long-run printing.

(Printing original plate)
In the method for producing a printing plate of the present embodiment, in the exposure step, a relief is formed on the photosensitive resin composition layer by exposure to obtain a printing original plate, and in the development step, the photosensitive resin composition layer is not yet exposed. The exposed portion is removed by adhering or adsorbing to a developing medium, and developed.
The printing original plate comprises at least a support (a) and a photosensitive resin composition layer (b) laminated on the support (a) before the photosensitive resin composition layer is exposed to light. have In this specification, such a structure may be referred to as a "photosensitive resin structure for printing plates".
That is, as will be described later, a photosensitive resin composition for a printing plate is subjected to pattern exposure to form a relief to form a printing original plate. By removal, a printing plate is obtained.

<Support (a)>
Examples of the support (a) include, but are not limited to, polyester films, polyamide films, polyacrylonitrile films, polyvinyl chloride films and the like.
Among these, a polyester film is preferable as the support (a).
The polyester used for the support (a) is not particularly limited, but examples thereof include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like.
The thickness of the support (a) is not particularly limited, but preferably 50 to 300 μm.
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 below. The adhesive layer is not particularly limited, but includes, for example, the adhesive layers described in International Publication No. 2004/104701, Japanese Patent No. 3094647, and Japanese Patent No. 2634429.

<Photosensitive resin composition layer (b)>
The photosensitive resin composition for a printing plate has a photosensitive resin composition layer (b) on a support (a).
The photosensitive resin composition layer (b) may be directly laminated on the support (a), or may be indirectly laminated via the adhesive layer or the like.

The unexposed photosensitive resin composition layer (b) includes a polymer (b-1) described later and a liquid component (b-2) that is liquid at 0 ° C. or higher and lower than 40 ° C. (hereinafter, simply liquid component (b- 2) may be described.), and further preferably contains a photopolymerization initiator (b-3).
Moreover, the photosensitive resin composition layer (b) may further contain an auxiliary additive component, if necessary.
Each component will be described in detail below.

[Polymer (b-1)]
The polymer (b-1) is not particularly limited, but preferably has a number average molecular weight (Mn) of 3,000 or more and 70,000 or less as measured by gel permeation chromatography (GPC). It is more preferably 4000 or more and 60000 or less, and still more preferably 4000 or more and 50000 or less.
When the Mn of the polymer (b-1) is 3000 or more, the photosensitive resin composition is less likely to cut when the development medium separates from the printing original plate in the development step described later, and the unexposed photosensitive resin composition is printed. It becomes difficult to remain as a residue on the original plate. Further, when the Mn is 70,000 or less, suitable fluidity can be obtained even at low temperatures in removing the unexposed photosensitive resin composition, and adhesion and/or adsorption to the developing medium is facilitated.
The Mn of the polymer (b-1) can be measured by the method described in Examples below.
The Mn of the polymer (b-1) can be controlled within the above numerical range by adjusting polymerization conditions such as polymerization monomers and polymerization time.

In addition, from the viewpoint of suppressing deterioration of solid print quality due to breakage or abrasion of the printing plate, it is preferable that the polymer (b-1) has an unsaturated carbon bond.
The unsaturated carbon bond refers to a carbon-carbon double bond or triple bond, and the functional group having an unsaturated carbon bond is not particularly limited. A (meth)acrylic group having highly efficient photocrosslinkability is preferred from the viewpoint of suppressing strain that causes deterioration of solid print quality.

The method for identifying the unsaturated carbon bond of the polymer (b-1) is not limited to the following. For example, after separating the polymer components by liquid chromatography (LC), infrared absorption spectroscopy (IR ) can be used. Specifically, when identifying carbon-carbon double bonds, 3000 to 3100 cm ^-1 , 1630 to 1670 cm ^-1 , 1410 to 1420 cm ^-1 , 2 at 905 to 995 cm ^-1 , around 670 to 730 cm ^-1 , etc. Confirm the presence or absence of the absorption band of
Other methods for identifying unsaturated carbon bonds include, for example, a method using nuclear magnetic resonance (NMR). Specifically, in the case of a carbon-carbon double bond, ¹ H NMR is used to confirm the presence or absence of a peak around a chemical shift value of 6 to 8 ppm, and ¹³ C NMR is used to confirm a chemical shift value of around 100 to 160 ppm. A method of confirming the presence or absence of the peak of is mentioned.

The polymer (b-1) is not particularly limited, but may be, for example, a linear, branched or dendritic polymer, and may be a homopolymer or a copolymer. The copolymers may be random, alternating, or block copolymers.
Suitable polymers (b-1) are, for example, fully or partially hydrolyzed polyvinyl esters, partially hydrolyzed polyvinyl acetates, polyvinyl alcohol derivatives, partially hydrolyzed vinyl acetate/ These include those conventionally used in the manufacture of printing plates such as alkylene oxide graft copolymers or polyvinyl alcohols subsequently acrylated by polymer-analogous reactions, polyamides and mixtures thereof. Other examples include thermoplastic elastomer binders.
Block copolymers of thermoplastic elastomers include those comprising at least one block comprising alkenyl aromatic monomeric units and at least one block comprising 1,3-diene monomeric units. Examples of alkenyl aromatic compounds forming alkenyl aromatic monomer units include styrene, α-methylstyrene, and vinyltoluene.

Furthermore, the polymer (b-1) preferably contains a compound having a urethane structure from the viewpoint of suppressing deterioration of solid print quality due to abrasion of the printing plate during long-run printing. Polyurethane is more preferred.
Methods for identifying polyurethane include, but are not limited to, a method of separating polymer components by liquid chromatography (LC) and then identifying by nuclear magnetic resonance (NMR) or mass spectrometry (MS). , a method of identification by gas chromatography mass spectrometry (GC/MS), and the like.
Polyurethane as the polymer (b-1) is not particularly limited, but may have a (meth)acrylic group as an unsaturated carbon bond at the terminal group. As a method for producing a polyurethane having a (meth)acrylic terminal group, for example, a diol having a repeating unit in the molecule is reacted with a diisocyanate to form a polyurethane having an isocyanate group at the terminal with an arbitrary molecular weight, Next, there is a method of reacting the polyurethane with a compound containing active hydrogen and (meth)acrylic group in one molecule. As another method, a diol having a repeating unit in the molecule and a diisocyanate are reacted to first form a polyurethane having a terminal hydroxyl group with an arbitrary molecular weight, and then the polyurethane and an isocyanate in one molecule are formed. Also included are methods of reacting with compounds containing groups and (meth)acrylic groups.
The polyurethane structure obtained by the production method described above is a structure formed by reacting a diol having repeating units in the molecule with a diisocyanate.
Hereinafter, the "polyurethane having (meth)acrylic groups at the terminal groups" synthesized by the above method will be referred to as "unsaturated prepolymer".

The "diol having a repeating unit in the molecule" used in the production of the unsaturated prepolymer is not limited to the following, but includes, for example, a polyester diol composed of a dicarboxylic acid and a diol; a polyether diol; a polyether polyester copolymerized diol a 1,2-polybutadiene compound having a terminal hydroxyl group; The diols having repeating units in the molecule may be used singly or in combination of two or more.

The dicarboxylic acid constituting the polyester diol is not particularly limited below, but examples include succinic acid, glutaric acid, adipic acid, pimenphosphoric acid, suberic acid, azelaic acid, sebacic acid, maleic acid, terephthalic acid, isophthalic acid, and 1,5-naphthalenedicarboxylic acid and the like.
Examples of diols constituting the polyester diol include, but are not limited to, 1,4-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and neopentyldiol. , 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, and diethylene glycol (dioxyethylenediol).

Examples of the polyether diol include, but are not limited to, polyoxyethylene diol, polyoxypropylene diol, polyoxytetramethylene diol, polyoxy 1,2-butylene diol, and polyoxyethylene/polyoxypropylene random copolymer. diols, polyoxyethylene/polyoxypropylene block copolymer diols, polyoxyethylene/polyoxytetramethylene random copolymer diols, polyoxyethylene/polyoxytetramethylene block copolymer diols, and the like.

The polyether polyester copolymer polyol is not limited to the following, but for example, the repeating unit forming the molecular chain of the polyether polyol described above and the repeating unit forming the molecular chain of the polyester polyol described above are block or random. A copolymer having a structure linked to

The 1,2-polybutadiene compound having terminal hydroxyl groups may be a hydrogenated compound. Examples of the 1,2-polybutadiene compound having a terminal hydroxyl group include, but are not limited to, poly-1-butene hydrides and 1,2-polybutadiene hydrides. The number of terminal hydroxyl groups is not particularly limited, but from the viewpoint of improving solid quality deterioration due to breakage and abrasion during printing of the finally obtained printing plate, it is preferably 1.2 or more per molecule, and 1.5 It is more preferably 1 or more, and further preferably 2.0 or less.

Examples of the diisocyanate include, but are not limited to, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and norbornene diisocyanate. etc.
A diisocyanate is used individually by 1 type or in combination of 2 or more types.

The content of the polymer (b-1) in the photosensitive resin composition layer (b) is such that the fluidity of the unexposed photosensitive resin composition is in an appropriate range even under low temperature conditions, and good removability is achieved. From the viewpoint of ensuring, when the total amount of the photosensitive resin composition layer (b) is 100% by mass, it is preferably 40% by mass or more, more preferably 40 to 90% by mass, and 50 to 90% by mass. %, and even more preferably 60 to 80% by mass.

[Liquid component (b-2) that is liquid at 0°C or higher and lower than 40°C]
As described above, the photosensitive resin composition layer (b) preferably contains a liquid component (b-2) that is liquid at 0°C or higher and lower than 40°C.
The term “liquid” as used herein means a property having properties such that it can be easily flow-deformed and can be solidified into the deformed shape by cooling.
Moreover, the liquid component (b-2) may be liquid at any temperature within the temperature range of 0° C. or higher and lower than 40° C., and does not need to be liquid over the entire temperature range.

The liquid component (b-2) has a number of The average molecular weight (Mn) is preferably 100 or more and 1500 or less, more preferably 110 or more and 1000 or less, and even more preferably 130 or more and 800 or less.
For the same reason, the content of the liquid component (b-2) in the unexposed photosensitive resin composition is preferably 8% by mass or more and 70% by mass or less, and 5% by mass or more and 50% by mass. It is more preferably 10% by mass or more and 40% by mass or less.
The number average molecular weight of the liquid component (b-2) can be measured, for example, by gel permeation chromatography (GPC). Further, if the structure of the liquid component is known, the molecular weight can be calculated based on the atomic weight. Specifically, it can be measured by the method described in the examples below.
The content of the liquid component (b-2) is calculated, for example, by the area ratio of the measurement curve when the solvent-soluble matter such as tetrahydrofuran (THF) in the photosensitive resin composition layer (b) is measured by GPC measurement. can.

Examples of such a liquid component (b-2) include, but are not limited to, ethylenically unsaturated compounds.
An ethylenically unsaturated compound is a compound having a radically polymerizable unsaturated double bond. Examples include, but are not limited to, olefins such as ethylene, propylene, vinyltoluene, styrene, and divinylbenzene; acetylenes; (meth)acrylic acid and/or derivatives thereof; haloolefins; saturated nitriles; unsaturated amides such as acrylamide and methacrylamide and derivatives thereof; unsaturated dicarboxylic acids such as maleic anhydride, maleic acid and fumaric acid and derivatives thereof; vinyl acetates; N-vinylpyrrolidone; N-vinylcarbazole; and N-substituted maleimide compounds.
Among these, from the viewpoint of solid quality stability by improving ultraviolet curability and printing durability of the photosensitive resin composition layer (b) after exposure curing, ethylenically unsaturated compounds include (meth)acrylic acid and / or derivatives thereof are preferred.

Examples of the derivatives include, but are not limited to, cycloalkyl, bicycloalkyl, cycloalkenyl, bicycloalkenyl, etc. alicyclic compounds; benzyl, phenyl, phenoxy, or naphthalene skeleton, anthracene Aromatic compounds having skeleton, biphenyl skeleton, phenanthrene skeleton, fluorene skeleton, etc.; compounds having alkyl group, halogenated alkyl group, alkoxyalkyl group, hydroxyalkyl group, aminoalkyl group, glycidyl group, etc.; alkylene glycol, polyoxyalkylene ester compounds with polyhydric alcohols such as glycol, polyalkylene glycol and trimethylolpropane; and compounds having a polysiloxane structure such as polydimethylsiloxane and polydiethylsiloxane.

The ethylenically unsaturated compound may also be a heteroaromatic compound containing elements such as nitrogen and sulfur.

Examples of (meth)acrylic acid and/or derivatives thereof include, but are not limited to, diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol; Diacrylates and dimethacrylates of polyethylene glycol, butylene glycol; trimethylolpropane tri(meth)acrylate; dimethyloltricyclodecane di(meth)acrylate; isobornyl (meth)acrylate; phenoxypolyethylene glycol (meth)acrylate; (Meth)acrylate and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types.

From the viewpoint of improving the printing durability of the finally obtained printing plate and improving the solid quality stability during long-run printing, at least one ethylenically unsaturated compound as the liquid component (b-2) is It is preferable to use more than one type of (meth)acrylate, more preferably at least one type or more of bifunctional (meth)acrylate.

The number average molecular weight (Mn) of the ethylenically unsaturated compound controls the fluidity of the photosensitive resin composition within a suitable range, and obtains good removability even under low temperature conditions of 0°C or higher and lower than 40°C. Therefore, it is preferably 100 or more and 1500 or less, more preferably 110 or more and 1000 or less, and even more preferably 130 or more and 800 or less.

The content of the ethylenically unsaturated compound, which is the liquid component (b-2), in the photosensitive resin composition layer (b) is, when the total amount of the photosensitive resin composition layer (b) is 100% by mass, From the viewpoint of controlling the fluidity under low temperature conditions of 0 ° C. or higher and lower than 40 ° C. to a suitable range, it is preferably 2 mass% or more and less than 60 mass%, more preferably 5 mass% or more and 50 mass% or less. More preferably, it is at least 40% by mass.

As other liquid components (b-2), the flexibility of the printing plate finally obtained in the production method of the present embodiment is improved to improve the solid quality, and the residual stress and strain can be easily relaxed. From the viewpoint of improving quality stability, it is preferable to contain a plasticizer.
Examples of plasticizers include, but are not limited to, liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, and liquid styrene-butadiene copolymer. liquid dienes such as naphthenic oil, hydrocarbon oils such as paraffin oil; liquid acrylonitrile-butadiene copolymers, liquid styrene-butadiene copolymers and other liquid diene-based conjugated diene rubbers; number average molecular weight of 2000 or less polystyrene; ether-based plasticizers; and ester-based plasticizers obtained by a condensation reaction between a compound having a hydroxyl group and a carboxylic acid compound. In particular, an ester plasticizer is preferable from the viewpoint of compatibility with the polymer.

The ester plasticizer, which is the liquid component (b-2), has flexibility for realizing high solid quality of the printing plate, compatibility between the polymer and the plasticizer described above, and reduction of precipitation of the plasticizer. From the viewpoint of the balance of long-term storage stability, a compound having a structure represented by the following formula (1) is preferred.
_{R2 ( OR3} ) _nOCOR1COO ( _R3O ) _{nR2 Formula} (1)
(where R ₁ is a divalent saturated aliphatic hydrocarbon group having 4 to 8 carbon atoms, R ₂ is a monovalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, R ₃ is an ethylene group and/or a propylene group, n represents an integer of 0 to 5.)
Examples of the compound having the structure represented by formula (1) include di-2-ethylhexyl adipate, diisodecyl adipate, dibutoxyethyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, and di-2-ethylhexyl sebacate. is mentioned.

The identification method of the ester plasticizer is not limited to the following. There is a method of separating a "liquid component" and then identifying it by nuclear magnetic resonance (NMR) or mass spectrometry (MS).
These plasticizers may have a hydroxyl group or a carboxyl group. Moreover, a photopolymerizable reactive group such as a (meth)acryloyl group may be added to these plasticizers.
These other plasticizers may be used alone or in combination of two or more.

The content of the plasticizer in the photosensitive resin composition layer (b) is 100% by mass based on the total amount of the photosensitive resin composition layer (b) from the viewpoint of improving the solid quality during printing by improving the flexibility of the printing plate. , preferably 0 to 30% by mass, more preferably 6 to 30% by mass, and even more preferably 6% to 25% by mass.

[Photopolymerization initiator (b-3)]
The photosensitive resin composition layer (b) preferably contains a photopolymerization initiator (b-3).
The photopolymerization initiator (b-3) is a compound that absorbs light energy and generates radicals. and a compound having a site functioning as a decay-type photopolymerization initiator in the same molecule.

Examples of such a photopolymerization initiator (b-3) include, but are not limited to, benzophenone, 4,4-bis(diethylamino)benzophenone, 3,3′,4,4′-benzophenonetetracarboxylic anhydride 3,3′,4,4′-Tetramethoxybenzophenone and other benzophenones; t-butylanthraquinone, 2-ethylanthraquinone and other anthraquinones; 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone thioxanthones such as; Michler's ketone; diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-hydroxycyclohexyl-phenylketone , 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-propan-1-one, 2-benzyl-2- acetophenones such as dimethylamino-1-(4-morpholinophenyl)-butanone and trichloroacetophenone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; 2,4,6-trimethylbenzoyl Acylphosphine oxides such as diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 1,7-bisacridinylheptane; 9-phenylacridine; azo compounds such as azobisisobutyronitrile, diazonium compounds and tetrazene compounds.
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 (b-3) in the photosensitive resin composition layer (b) prevents the finally obtained printing plate from being damaged during long-run printing, and suppresses solid quality deterioration due to damage to the printing plate. From the viewpoint of doing so, when the total amount of the photosensitive resin composition layer (b) is 100% by mass, it is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, and 0.3 to 5% by mass. % is more preferred.

[Auxiliary additive ingredients]
Examples of auxiliary additive components include, but are not limited to, thermal polymerization inhibitors, antioxidants, light stabilizers, ultraviolet absorbers, dyes/pigments, and the like.

As the thermal polymerization inhibitor and antioxidant, those commonly used in the field of resin materials or rubber materials can be used, and examples thereof include phenolic materials.
Phenolic materials include, but are not limited to, vitamin E, tetrakis-(methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate)methane, 2, 5-di-t-butyl hydroquinone, 2,6-di-t-butyl-p-cresol, 3,9-bis-{1,1-dimethyl-2-[3-(3-t-butyl-4- Hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane, 2-t-butyl-6-(3-t-butyl-2-hydroxy- 5-methylbenzyl)-4-methylphenyl acrylate and the like.
Other examples of thermal polymerization inhibitors and antioxidants include phosphine-based materials such as triphenylphosphite.
The thermal polymerization inhibitor and the antioxidant may be used alone or in combination of two or more.

Examples of light stabilizers and ultraviolet absorbers include, but are not limited to, known benzophenone-based compounds, salicylate-based compounds, acrylonitrile-based compounds, metal complex-based compounds, and hindered amine-based compounds.
Dyes and pigments shown below may also be used as the ultraviolet absorber.
Examples of such light stabilizers and UV absorbers include, but are not limited to, 2-ethoxy-2'-ethyloxalic acid bisanilide, 2,2'-dihydroxy-4-methoxybenzophenone, bis( 1,2,2,6,6-pentamethyl-4-piperidyl)-decanedioate, 1,2,3-benzotriazole and the like.

Dyes and pigments are effective as coloring means for improving visibility.
Examples of dyes include, but are not limited to, water-soluble basic dyes, acid dyes, direct dyes, and water-insoluble sulfur dyes, oil-soluble dyes, disperse dyes, and the like. Anthraquinone dyes, indigoid dyes, and azo dyes are particularly preferred.
Examples of pigments include, but are not limited to, natural pigments, synthetic inorganic pigments, synthetic organic pigments, and the like. Synthetic organic pigments include azo-based pigments, triphenylmethane-based pigments, quinoline-based pigments, anthraquinone-based pigments, and phthalocyanine-based pigments.

(Preferred form of the printing plate manufacturing method of the present embodiment)
A preferred embodiment of the printing plate manufacturing method of the present embodiment will be described below. In addition, the manufacturing method of the printing plate of this embodiment is not limited to the following forms.
In the method for producing a printing plate of the present embodiment, the above-described photosensitive resin composition for a printing plate (a photosensitive resin composition laminated on a support) is used, and first, a step of irradiating ultraviolet rays from the support side. (first step), in the case of digital plate making, the infrared ablation layer is irradiated with infrared rays to draw a pattern, and in the case of analog plate making, the negative is brought into close contact with the photosensitive resin layer (second step). , a step of pattern exposure by irradiating the photosensitive resin composition layer with ultraviolet rays using the infrared ablation layer or negative with a pattern drawn as a mask (third step), and the unexposed area of the photosensitive resin composition layer. is removed (fourth step).
In this (fourth step), in the present embodiment, as described above, the temperature of the photosensitive resin composition in the unexposed area is set to 0° C. or higher and lower than 40° C., and development is performed by adhering or adsorbing to the development medium. conduct.
Thereafter, a step of post-exposure treatment is performed as necessary to obtain a printing plate of a cured product of the photosensitive resin composition layer.
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.

<First step>
In the first step, the photosensitive resin composition layer (b) is irradiated with ultraviolet rays from the support (a) side.
The ultraviolet irradiation method is not particularly limited, and can be carried out using a known irradiation unit. The wavelength of the ultraviolet rays to be irradiated is preferably 150-500 nm, more preferably 300-400 nm.
The ultraviolet light source is not limited to the following, but 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, and the like can be used.
The first step may be performed before or after the second step, which will be described later.

<Second step>
In the second step, when the infrared ablation layer is irradiated with infrared rays to draw a pattern, the drawing processing method is not particularly limited, and a known irradiation unit can be used. In addition, irradiation of infrared rays to the infrared ablation layer can be performed from the infrared ablation layer side.
The infrared ablation layer is pattern-irradiated with infrared rays to decompose the resin in the infrared-irradiated portion, and the pattern is drawn. Thereby, a mask for the infrared ablation layer can be formed on the photosensitive resin composition layer.
Infrared lasers used in the second step include, for example, 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. The laser system includes a rotating cylindrical drum that holds a photosensitive resin construction for the printing plate, an IR laser irradiation device, and a layout computer, and image information is transmitted directly from the layout computer to the laser device.
In the case of analog plate making in the second step, a mask can be similarly formed by using a negative film.

<Third step>
In the third step, the patterned infrared ablation layer or negative film is used as a mask to irradiate the photosensitive resin composition layer with ultraviolet rays for pattern exposure.
At this time, the light passing through the mask accelerates the curing reaction of the photosensitive resin composition layer, and the pattern formed on the infrared ablation layer or negative film is reversed and transferred to the photosensitive resin composition layer. be. The irradiation with ultraviolet rays may be performed on the entire surface or partially.

<Fourth step>
The fourth step is to remove the unexposed portion of the photosensitive resin composition layer.
In the fourth step (development step), the unexposed portion is removed by adhering or adsorbing the unexposed portion to the developing medium.
In the developing step in the manufacturing method of the present embodiment, the temperature of the unexposed photosensitive resin composition is set at 0°C or higher and lower than 40°C. By setting the temperature within the above range, the energy for heating can be reduced, and the residual stress and distortion of the printing plate caused by heating can be suppressed, so deformation of the printing plate during long-term storage and long-run printing. can be suppressed, and the solid quality stability can be improved.
Next, the unexposed portion is removed by adhering or adsorbing to the developing medium. As a step prior to removal, the unexposed portion may be removed in advance using a spatula or roll.
The development medium has an absorbent layer, which is brought into contact with the unexposed areas, deposits or absorbs away the unexposed areas, and removes the unexposed areas.
After that, a printing plate is produced by post-exposure treatment if necessary.
If an intermediate layer is provided between the infrared ablative layer and the photosensitive resin composition layer, it may be removed at the same time during the development step.

When the photosensitive resin composition is liquid at room temperature, in the first to third steps described above, the photosensitive resin composition is usually placed on the support inside a dedicated device (plate making machine). A predetermined forming step is included so that the film is formed into a thick film.
As described above, the exposure step when using a photosensitive resin composition that is liquid at room temperature is preferably carried out, for example, the following steps (A1) to (A3).
(A1):
A negative film is placed on an ultraviolet-transmissive glass plate (lower glass plate), the negative film is covered with a thin protective film, and a photosensitive resin composition is poured over it to give a constant plate thickness. A photosensitive resin composition layer forming step in which a base film that serves as a support is attached via a spacer, and then pressed with an ultraviolet-transmitting glass plate (upper glass plate) to form a photosensitive resin composition layer. .
When forming a printing plate (thickness of 4 mm or more) used for cardboard printing, in order to compensate for the strength of the relief against printing pressure during printing, the photosensitive resin composition layer on the upper glass plate side is provided with a base. It is preferable to form a shelf layer of In this case, before the relief exposure, a special negative film (masking film) is sandwiched between the upper glass plate and the base film to form the photosensitive resin composition layer.
(A2):
After the step of forming the photosensitive resin composition layer, actinic rays (e.g., rays having a wavelength distribution of 300 nm or more) using an ultraviolet fluorescent lamp as an actinic light source are irradiated from the upper glass plate side through the base film. A back exposure step for depositing a uniform thin cured resin layer (that is, a floor forming layer (back deposition layer)) on the entire surface of the base film side of the plate.
When a masking film is provided in the photosensitive resin composition layer forming step, the shelf layer is formed by the same exposure. In this case, it is called a masking exposure process.
Both the back deposit layer and the shelf layer are formed by curing the photosensitive resin composition layer on the side opposite to the relief forming layer side, i.e., the photosensitive resin composition layer on the support side. . When the entire photosensitive resin composition layer on the support side is cured, it becomes a back deposit layer, and when the photosensitive resin composition layer is partially cured according to the position of the relief forming layer, it becomes a shelf layer. .
(A3):
After the back exposure process or the masking exposure process, the photosensitive resin composition layer is irradiated with the same actinic rays as the upper part through the negative film from the lower glass side, and the image forming layer (relief forming layer) is deposited. Formation exposure process.
In the case where the shelf layer is formed by the masking exposure process, it is also a preferred embodiment to remove the masking film after the relief forming exposure process and then to form the back deposition layer on the entire surface of the base film by performing the back exposure process. one of.

(relief depth)
In the printing plate manufacturing method of the present embodiment, from the viewpoint of removability of the uncured photosensitive resin composition, the thickness of the relief-forming layer, that is, the relief depth, is 0.1 mm or more and 10.0 mm or less. It is preferably 0.5 mm or more and 3.0 mm or less, and further preferably 0.5 mm or more and 2.0 mm or less. Here, the relief depth is the length obtained by subtracting the height of the back deposition layer and/or the shelf layer from the plate thickness, that is, the depth of the printed image relief.
That is, if only the back deposited layer is formed, the height of the back deposited layer is subtracted from the plate thickness, if only the shelf layer is formed, the height of the shelf layer is subtracted, and if both are formed subtracts both heights.
When the relief depth is 0.1 mm or more, it is possible to secure the relief depth necessary for design printing. On the other hand, when the relief depth is 10.0 mm or less, it is possible to ensure a large contact area with the development medium relative to the volume of the uncured photosensitive resin composition in the development step, and the adsorption of the uncured photosensitive resin composition. Good removability is obtained.
The thickness of the relief forming layer (relief depth) can be controlled within the above numerical range by adjusting the exposure dose of actinic rays in the exposure step (A2) and adjusting the thickness of the shelf layer and/or the back deposition layer. can be done.

(Development medium used in the development process)
In the printing plate manufacturing method of the present embodiment, in the developing step, development is performed by attaching or adsorbing the photosensitive resin composition in the unexposed area to the developing medium.
The development medium preferably has an adsorption layer, and examples of the development medium include a spatula; a roll; and a wiper in which the adsorption layer is made of nonwoven fabric, sponge, woven fabric, knitted fabric, or the like.
In particular, a wiper is preferable from the viewpoint of preventing damage to the printing plate in the development process, and the unexposed photosensitive resin composition is effectively absorbed when the shape of the wiper is restored, and the unexposed photosensitive resin composition can be removed. is preferably 30% or more and 99% or less, more preferably 35% or more and 99% or less, and even more preferably 40% or more and 99% or less.

The elastic recovery rate of the wiper, which is a developing medium, can be measured using a MCT-50 microcompression tester manufactured by Shimadzu Corporation.
The test conditions are a load-unload mode in which the sample is loaded to the maximum test force and then unloaded to the minimum test force, and measurements are taken.
The minimum test force is set to 0.05 mN, and the maximum test force is set to the test force when the wiper thickness d is deformed by 10% in the compression mode.
Under the above conditions, the elastic recovery rate is calculated as follows.
Elastic recovery rate (%) = L2/(L1-L2) x 100
L1: Displacement difference between maximum test force and minimum test force in load mode
L2: Displacement difference between maximum test force and minimum test force in unloading mode

(Recovery and reuse of photosensitive resin composition in unexposed area)
In the printing plate manufacturing method of the present embodiment, the photosensitive resin composition in the unexposed areas adhered or adsorbed to the development medium in the above-described development step is recovered as a photosensitive resin composition in manufacturing a new printing plate. It can have a process. The recovered photosensitive resin composition can be reused as a photosensitive resin composition in the production of new printing plates.
The step of recovering the unexposed photosensitive resin composition is preferably performed under temperature conditions of 0° C. or more and less than 40° C. in the development step.
The recovered photosensitive resin composition may be put into an exposure machine when manufacturing a new printing plate. You may use the photosensitive resin composition collect|recovered like this.
The exposing machine into which the recovered photosensitive resin composition is charged refers to an exposing machine equipped with a unit for laminating a support and a photosensitive resin in layers. When filling the photosensitive resin composition into the unit, A recovered photosensitive resin composition can be used.
Use of the recovered resin reduces waste and also reduces material costs.
In the printing plate manufacturing method of the present embodiment, the temperature of the photosensitive resin composition in the development step is a low temperature condition of 0° C. or more and less than 40° C., and even if heating is required, the heating is small. Thermal deterioration of the recovered photosensitive resin composition can be suppressed. Therefore, it is possible to maintain quality such as solid quality even in new printing plates manufactured using the recovered photosensitive resin composition.

Specifically, the printing plate manufacturing method of the present embodiment has the following effects (1) to (5).
(1) Removability of the unexposed photosensitive resin composition in the development process is improved.
(2) The photosensitive resin composition contains a polymer and a "liquid component" that is liquid at 0 ° C. or more and less than 40 ° C., the number average molecular weights of the polymer and the liquid component are specified, and the photosensitive resin composition By specifying the content of the liquid component with respect to the total amount of the material, a large amount of the unexposed photosensitive resin composition can be retained in the void portions of the developing medium even under relatively low temperature conditions, and high recovery efficiency can be achieved. .
(3) The development medium has an appropriate elastic recovery rate, so that the unexposed photosensitive resin composition can be easily separated by applying pressure to the development medium, and the recovery rate of the photosensitive resin composition is improved. Improvement is possible.
(4) In the development process, it is possible to remove and recover the unexposed photosensitive resin composition without applying excessive pressure, heating, etc., thereby preventing deterioration of the photosensitive resin composition, Furthermore, since the inclusion of impurities derived from the developing medium can be reduced, a high-quality photosensitive resin composition can be reused.
(5) It is possible to reduce the frequency of replacement of the developing medium because the residue of the deteriorated photosensitive resin composition remaining on the developing medium and the deterioration of the developing medium itself caused in the developing process are small.

[Printing method]
The printing method of this embodiment includes a step of manufacturing a printing plate by the method of manufacturing a printing plate of this embodiment described above, and a step of printing using the manufactured printing plate.
In particular, it is a preferable aspect to manufacture a flexographic printing plate by the method for manufacturing a printing plate of the present embodiment and carry out flexographic printing.

EXAMPLES The present invention will be described in more detail below with specific examples and comparative examples, but the present invention is not limited by the following examples.

[Physical properties and characteristics of the photosensitive resin composition]
The physical properties and characteristics of the photosensitive resin compositions used in Examples and Comparative Examples described later are shown below.

<GPC measurement>
GPC measurement is performed under the following conditions, and the polymer contained in the photosensitive resin composition (high molecular weight in unsaturated prepolymer compositions 1 to 10, "Toughprene A" manufactured by Asahi Kasei Corporation), Matsumura Oil, a liquid component The number average molecular weight of "Smoyl P350" (hereinafter referred to as "P350") manufactured by K.K.
Equipment: "HLC-8220GPC" manufactured by Tosoh Corporation
Column: "TSLgelGMHXL" manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran Flow rate: 1 ml/min Injection volume: 100 microliters Detector: RI detector Calibration curve standard: Polystyrene (molecular weight 500 to 1,260,000)
Sample: 0.3% by mass tetrahydrofuran solution Regarding the molecular weights of other liquid components, the number average molecular weight was obtained by molecular weight calculation from the structural formula.

<Relief depth>
The thickness of the relief-forming layer (relief depth) was measured as follows.
Using an ABS digimatic indicator ID-C112 (manufactured by Mitutoyo Co., Ltd.) measuring instrument, the thickness of the relief forming layer, the shelf layer and the back deposition layer was measured, and the relief depth was calculated by the following formula.
The relief-forming layer is a layer formed in (A3) of <Forming/exposure step> described later.
The shelf layer is a layer formed in (A2) of <Molding/exposure step> described later.
The back deposition layer is a layer formed in (A2) of <Forming/exposure step> described later.
Relief depth (mm) = thickness of entire printing plate (mm) - (thickness of back deposit layer and/or shelf layer + thickness of support) (mm)

[Production of Development Medium (Nonwoven Fabric)]
A nonwoven fabric prepared by the following method was used as the developing medium used in the following examples and comparative examples.

(Production example of nonwoven fabric)
Polyethylene terephthalate (PET) was discharged from a spunbond spinneret (V-type nozzle) at a spinning temperature of 290 ° C., and the yarn was symmetrically cooled from both sides by a cooling device directly below the spinneret (both at a wind speed of 0.5 m / s), continuous long fibers (fiber diameter 16 μm) were obtained by drawing with a draw jet, and the fibers were opened and dispersed and deposited on a web conveyor to form a web.
Next, a PET solution was spun into a superfine fiber nonwoven fabric layer (I layer, fiber diameter 3 μm) at a spinning temperature of 290° C. by a meltblowing method, and was blown onto the above web. At this time, the distance from the meltblown nozzle to the web was set to 300 mm, the suction force on the collecting surface immediately below the meltblown nozzle was set to 0.2 kPa, and the wind speed was set to 7 m/sec.
Further, a continuous filament web (fiber diameter 16 μm) produced by the same spunbond method as above was laminated on the ultrafine fiber nonwoven fabric layer (I layer) to obtain a laminated web.
Further, the laminated web was integrated with a calender roll (roll temperature: 220°C, linear pressure: 500 N/cm).

[Manufacture of flexographic printing plate]
In the following examples and comparative examples, dry development was carried out using the above nonwoven fabric as a developing medium to produce flexographic printing plates.

(Production Examples 1 to 10 Production of unsaturated prepolymer compositions 1 to 10)
Unsaturated prepolymer compositions 1 to 10 used in photosensitive resin compositions were produced as follows.
As the diol, poly(3-methyl-1,5-pentanediol adipate) diol ("Kurapol P3010" manufactured by Kuraray Co., Ltd., hereinafter abbreviated as "P3010") in the amount described in Table 2, polyoxy Ethylene (EO)-oxypropylene (PO) block copolymerized diol (“Sannics PL2100” manufactured by Sanyo Chemical Industries, Ltd., hereinafter abbreviated as “PL2100”), 0.03 g of dibutyltin dilaurate were added, and 40 ℃ to obtain a mixture.
To the resulting mixture, an amount of tolylene diisocyanate ("Coronate T80" manufactured by Nippon Polyurethane Co., Ltd., hereinafter abbreviated as "TDI") in the amount shown in Table 2 below is added and further stirred to form a mixture. Obtained.
When the mixture became uniform, the mixture was heated to 80° C. and reacted for 4 to 5 hours to prepare a prepolymer precursor having isocyanate groups at both ends. At this time, 1000 g of dehydrated 2-butanone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added in order to lower the viscosity of the reaction solution during the production of unsaturated prepolymers 6 to 9.
Poly(oxypropylene) glycol monomethacrylate ("Blenmer PP" manufactured by NOF Corporation, hereinafter "PPM ) was added and reacted for 2 hours. It should be noted that, during the production of the unsaturated prepolymer 10, the isocyanate groups were deactivated by adding ethanol instead of PPM.
A portion of the obtained reaction product was taken out and subjected to IR spectroscopic measurement to confirm the disappearance of the isocyanate group. Unsaturated prepolymer compositions 6 to 10 were freed of solvent using an evaporator.
Unsaturated prepolymer compositions 1-10 were obtained as described above.
GPC measurements were performed on the unsaturated prepolymer composition. The number average molecular weights of the high molecular weight substances derived from the unsaturated prepolymer component in the unsaturated prepolymer composition are shown in [Table 2] below.

[Manufacture of flexographic printing plate]
(Preparation of photosensitive resin compositions of Examples 1 to 25, 27 to 33 and Comparative Examples 1 and 2)
To the unsaturated prepolymer composition (polymer) obtained in the above production example, liquid components shown in Tables 1 and 3 below, a photopolymerization initiator and an antioxidant as auxiliary agents were added, and the mixture was heated to 60°C. to obtain photosensitive resin compositions shown in Tables 3 to 6 below.

(Preparation of photosensitive resin composition of Example 26)
Using Tufprene A (a styrene-butadiene block copolymer manufactured by Asahi Kasei Co., Ltd.) as a polymer, the raw materials shown in Table 5 were kneaded at 160° C. in a pressure kneader to obtain a photosensitive resin composition.

Using the resulting photosensitive resin composition, a flexographic printing plate was produced by sequentially performing the following molding/exposure process, development process, post-exposure process, and drying process.

(Molding/exposure process)
Molding and exposure were performed according to (A1) to (A3) using "ALF-213E plate making machine" manufactured by Asahi Kasei Corporation.
(A1):
A negative film is placed on an ultraviolet-transmissive glass plate (lower glass plate), the negative film is covered with a thin protective film, and a photosensitive resin composition is poured over it to give a constant plate thickness. A base film serving as a support was laminated with a spacer interposed therebetween, and was further pressed with an ultraviolet-transmitting glass plate (upper glass plate) to form a photosensitive resin composition layer. In order to compensate for the strength of the relief against printing pressure during printing, a shelf layer serving as a base was formed on the portion of the photosensitive resin composition layer on the upper glass plate side. Before the relief exposure, a special negative film (masking film) was sandwiched between the upper glass plate and the base film to form a photosensitive resin composition layer.
(A2):
After molding the photosensitive resin composition layer, an actinic ray (light having a wavelength distribution of 300 nm or more) using an ultraviolet fluorescent lamp or the like as an actinic light source was irradiated from the upper glass plate side through the base film.
Since the masking film was provided in the step of forming the photosensitive resin composition layer, the shelf layer was formed by the same exposure.
(A3):
After the masking exposure step, the photosensitive resin composition layer was irradiated with actinic rays similar to those for the upper portion through a negative film from the lower glass side to carry out a relief forming exposure step for forming an image.

A photosensitive resin composition layer having a negative film for the shelf layer was formed in the same manner as in (A1) above.
Here, the negative film has a shelf layer of 300 mm×500 mm and a linear unexposed portion of 500 μm width in a solid image of 200 mm×250 mm (hereinafter referred to as “white space” or “white line”). The one with the design to be formed was used.
Then, the photosensitive resin composition layer was exposed as described in (A2) and (A3) above to obtain flexographic printing original plates having a plate thickness of 3 mm and relief depths shown in Tables 3 to 6 below.
In order to adjust the relief depth, the masking exposure amount was adjusted as appropriate.
The relief exposure was performed under the exposure condition of 600 mJ/cm ² .

(Development process)
After recovering and removing the unexposed resin using a rubber spatula, the exposed flexographic printing original plate was fixed using a double-sided adhesive tape to a 35 cm diameter metal roll driven by a motor.
A nonwoven fabric for thermal development was placed so as to be able to pass between a plurality of heatable metal rolls with a diameter of 5 cm.
An infrared lamp for heating the photosensitive resin composition layer relatively quickly was fixed on the metal roll holding the flexographic printing original plate.
When heating, the infrared lamp was turned on, and the heated metal roll was slowly rotated (2 rpm) by a motor. On a metal roll, the nonwoven fabric was brought into contact with the photosensitive resin composition surface of the flexographic printing original plate at a contact pressure of 1.0×10 ⁵ Pa and allowed to pass through.
When not heating, the metal roll was rotated slowly (2 rpm) by a motor in a temperature-controlled room. On a metal roll, the nonwoven fabric was brought into contact with the photosensitive resin composition surface of the flexographic printing original plate at a contact pressure of 1.0×10 ⁵ Pa and allowed to pass through.
When cooling to 0° C. or less, the metal roll on which the flexo original plate was set was placed in a freezer and the temperature was controlled, and then the metal roll was slowly rotated (2 rpm) by a motor. On a metal roll, the nonwoven fabric was brought into contact with the photosensitive resin composition surface of the flexographic printing original plate at a contact pressure of 1.0×10 ⁵ Pa and allowed to pass through.
The roll holding the original flexographic printing plate was cycled 15 times to remove the unexposed portion of the photosensitive resin composition layer.

(Post-exposure process)
Post-exposure was carried out by an underwater exposure method using "AL-200UP type post-exposure machine" manufactured by Asahi Kasei Co., Ltd. equipped with both an ultraviolet fluorescent lamp and a germicidal lamp.
Exposure was performed at an exposure time of 2,000 mJ/cm ² for an ultraviolet fluorescent lamp and 2,000 mJ/cm ² for a germicidal lamp on the surface of the photosensitive resin composition.

<Drying process>
Using "ALF-DRYER" manufactured by Asahi Kasei Co., Ltd., the post-exposed plate was dried for about 30 minutes until moisture on the surface was removed to obtain a flexographic printing plate.

[Evaluation of flexographic printing plate]
<Evaluation of White Area Depth (Residue)>
Using μDEPTH & HEIGHT MEASURING SCOPE KY-90 (manufactured by Nissho Seimitsu Optics Co., Ltd.), the groove shape of the blank line with a line width of 500 μm was observed to measure the groove depth.
The evaluation criteria for the measurement results are shown below.
In the following evaluation criteria, A to D were evaluated as being practically usable without problems.
(Evaluation criteria)
A: 151 μm or more in depth B: 121 to less than 151 μm in depth C: 91 to less than 121 μm in depth D: 70 to less than 91 μm in depth E: Less than 70 μm in depth

<Evaluation of solid image print quality>
Corrugated cardboard printing was carried out under the following conditions for the solid portion of the rectangular design of 200 mm×250 mm of the obtained flexographic printing plate.
Printer: Umetani Seisakusho Co., Ltd. EQOS UPS-1.2Mx1.8M
(two-color machine)
Anilox: 60 degrees, 250 LPI, doctor method Printing speed: 150 sheets/minute Ink: Sakata Inx Co., Ltd., FK-Flemio black Ink viscosity: 9 seconds/Zahn cup #4, 23°C
Cardboard sheet: A-stage sheet, C5 (about 140 g/m ² ) surface liner, core 120 g/m ²
Printing was performed on 10 sheets as a guideline for stabilizing the ink transfer density to the cardboard sheet, and the 9th and 10th sheets were sampled and evaluated.
When evaluating long-run printing, printing was performed for the number of sheets, which will be described later, and the final two sheets were sampled for evaluation.
Three types of evaluation were performed: initial printing, long-term storage, and long-run.
The printed matter was visually observed, and the following ranking was given according to the concealability of the ink in the concave portions on the surface of the corrugated cardboard sheet.
A rank: Ink adhered to the entire surface B rank: There are spots where ink does not adhere C rank: Many recesses have spots where ink does not adhere D rank: Dots A state in which areas where ink does not adhere to the surface are arranged in a line without contact Rank E: A state in which there is a streak-like area where ink does not adhere In this evaluation, A to D can be used practically evaluated as

[Evaluation of solid image printing quality during long-term storage]
After the obtained flexographic printing plate was stored at 25° C. for 3 months, it was evaluated based on the evaluation method for solid image printing quality described above.

[Evaluation of solid image print quality during long-run printing]
Using the obtained flexographic printing plate, printing was performed 10,000 times by the above-described printing method, and solid image printing quality was evaluated.

<Evaluation method for bleeding out>
A bleed-out test was used to evaluate the compatibility of the components contained in the photosensitive resin composition.
After the obtained flexographic printing plate was stored at −10° C. for one month, the surface condition was checked. If precipitation of a liquid component was observed on the surface, there was bleed-out, and if not, there was no broad-out. evaluated as

<Evaluation of thermal deterioration of the recovered photosensitive resin composition>
Using the photosensitive resin composition described in Example 1, the unexposed photosensitive resin composition is heated at the temperature shown in Table 7 for 30 minutes, and then allowed to cool to 25°C. 7 was repeated to obtain a pseudo-collected photosensitive resin composition.
After that, using the pseudo-collected photosensitive resin composition, the above nonwoven fabric was developed at the developing temperature shown in Table 7 (the temperature of the unexposed photosensitive resin composition), and a 200 mm × 250 mm rectangular design solid image was obtained. A flexographic printing plate with sections was prepared.
By performing the solid image printing quality evaluation described above using the produced flexographic printing plate, the development temperature, that is, the temperature of the unexposed photosensitive resin composition, affects the thermal deterioration of the recovered photosensitive resin composition. Evaluate the impact.
The photosensitive resin composition with 0 heating/cooling cycles is assumed to be a new photosensitive resin composition that has never been collected.
In addition, the photosensitive resin composition "developing temperature 25 ° C., number of cycles 10 times" in Table 7 is a photosensitive resin composition stored at a temperature condition of 25 ° C. for the time required for 10 cycles. represents
In Table 7, (Example 1') is a photosensitive resin composition stored at a temperature of 25°C for the time required for 10 cycles as the photosensitive resin composition in the manufacturing process of the flexographic printing plate of Example 1. This is a specific example in which development processing was performed at 25° C. using a flexible resin composition.
In (Comparative Example 3), a new photosensitive resin composition that was never recovered as a photosensitive resin composition in the manufacturing process of the flexographic printing plate of Example 1 was used, and development processing was performed at 120°C. This is a specific example.
Furthermore, in (Comparative Example 3'), in the manufacturing process of the flexographic printing plate of Example 1, the photosensitive resin composition was heated at 120°C for 30 minutes, and then allowed to cool to 25°C. This is an example in which development processing was carried out at 120° C. using one that was repeated 10 times.

The printing plate manufacturing method of the present invention has industrial applicability in a wide range of general commercial printing fields.

Claims (11)

An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
A method of manufacturing a printing plate, comprising
In the developing step, the temperature of the unexposed photosensitive resin composition is set to 0° C. or higher and lower than 40° C.
A method of making a printing plate. The unexposed photosensitive resin composition contains a polymer and a liquid component that is liquid at 0 ° C. or higher and lower than 40 ° C.,
The number average molecular weight of the polymer is 3000 or more and 70000 or less,
The number average molecular weight of the liquid component is 100 or more and 1500 or less,
The content of the liquid component with respect to the total amount of the unexposed photosensitive resin composition is 8% by mass or more and 70% by mass or less,
A method for producing a printing plate according to claim 1 . The polymer has unsaturated carbon bonds,
A method for manufacturing a printing plate according to claim 2 . The polymer contains a compound having a urethane structure,
A method for producing a printing plate according to claim 2 or 3. The unexposed photosensitive resin composition contains an ester plasticizer,
The method for manufacturing a printing plate according to any one of claims 1 to 4. The relief depth of the printing plate is 0.1 mm or more and 10.0 mm or less,
The method for manufacturing a printing plate according to any one of claims 1 to 5. recovering the unexposed portion of the photosensitive resin composition adhered or adsorbed to the development medium as a photosensitive resin composition in the production of a new printing plate;
The method for manufacturing a printing plate according to any one of claims 1 to 6. recovering the unexposed photosensitive resin composition adhered or adsorbed to the development medium;
used as a photosensitive resin composition in the production of new printing plates,
The method of manufacturing a printing plate according to any one of claims 1 to 7. An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
A method of manufacturing a printing plate having
The photosensitive resin composition used in the exposure step contains the recovered photosensitive resin composition,
The recovered photosensitive resin composition is recovered under a temperature condition of 0° C. or higher and lower than 40° C. in the developing step.
A method of making a printing plate. A step of manufacturing a printing plate by the method for manufacturing a printing plate according to any one of claims 1 to 9;
a printing step of printing using the manufactured printing plate;
A printing method comprising: An exposure step of exposing the photosensitive resin composition to form a relief;
A developing step in which the unexposed photosensitive resin composition in the exposing step is attached or adsorbed to a development medium and developed;
have
In the developing step, recovering the unexposed photosensitive resin composition at a temperature of 0° C. or more and less than 40° C.;
A method for recovering a photosensitive resin composition.