JP2015030122A - Flexographic printing plate and method for plate-making the same, laser engraving type flexographic printing plate rinse liquid, and laser engraving type flexographic printing plate plate-making kit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser engraving flexographic printing plate and a method for plate-making the same having an excellent rinsing property for engrave-residue generated by the laser engraving and having an excellent UV ink printing durability, and to provide a laser engraving flexographic printing plate rinse liquid as well as a laser engraving flexographic printing plate plate-making kit.SOLUTION: The method for plate-making flexographic printing plate is characterized in comprising: a step of preparing a laser engraving flexographic printing plate original plate having a crosslinked relief-formation layer; a step of imagewise-laser engraving the printing plate original plate; and a step of rinsing the engraved surface using an aqueous rinse liquid containing (component 1) organic solvent having a particular structure, (component 2) ampholytic surfactant and/or anionic surfactant, and (component 3) water.

Description

  The present invention relates to a flexographic printing plate and a plate making method thereof, a rinse liquid for a laser engraving type flexographic printing plate, and a laser engraving type flexographic printing plate making kit.

Many so-called “direct engraving CTP methods” have been proposed in which a relief forming layer is directly engraved with a laser to make a plate. In this method, the flexographic printing plate precursor is directly irradiated with a laser to cause thermal decomposition and volatilization by photothermal conversion, thereby forming recesses. In such a direct engraving CTP method, the image portion is irradiated with ultraviolet rays through a mask made by imagewise ablation of a black layer provided on a negative film or a relief forming layer in a conventional plate making process, that is, an image portion. Since the “exposure process” for curing, the “development process” for removing unexposed areas that become non-image areas, and the subsequent “drying process” and “post-exposure process” are unnecessary, the plate making process can be greatly simplified. The benefits are great.
As conventional flexographic printing plate precursors for laser engraving, for example, those described in Patent Documents 1 to 8 are known.

Patent Documents 1 to 4 disclose a flexographic printing plate precursor using a hydrophobic elastomer (rubber) as a relief layer binder, and Patent Document 5 discloses a flexographic printing plate precursor using a hydrophilic polyvinyl alcohol derivative. Is disclosed.
In Patent Document 6, as a technique for improving the rinsing property of a plate material using a hydrophobic elastomer, the relief forming layer contains porous inorganic fine particles, and the liquid engraving residue is adsorbed on the particles to improve the removability. Techniques for improving are disclosed.
Patent Document 7 discloses a technique for improving the rinsing property of engraving residue particularly in an alkaline rinsing liquid by containing a compound having a hydrolyzable silyl group and / or silanol group in a relief forming layer.
In Patent Document 8, a photosensitive resin composition capable of laser engraving contains an organosilicon compound to reduce the residue rate after engraving (because it is difficult to attach residue), and a cloth impregnated with an organic solvent. A technique that facilitates wiping off engraving residue is disclosed.

US Pat. No. 5,798,202 Japanese Patent Laid-Open No. 2002-3665 JP 2004-262135 A JP 2001-121833 A JP 2006-2061 A JP 2004-174758 A JP2011-148299A International Publication No. 2005/070691 Pamphlet

  Problems to be solved by the present invention include a laser engraving-type flexographic printing plate excellent in rinsing property of engraving residue generated by laser engraving and UV ink printing durability, a plate-making method thereof, a rinsing liquid for laser engraving-type flexographic printing plate, and It is to provide a laser engraving type flexographic printing plate making kit.

The above-described problems of the present invention have been solved by the following means <1>, <8>, <9> and <13>. They are listed together with <2> to <7> and <10> to <12>, which are preferred embodiments.
<1> A step of preparing a flexographic printing plate precursor for laser engraving having a crosslinked relief-forming layer, a step of laser engraving the printing plate precursor imagewise, and an engraved surface (component 1) represented by the following formula (I An organic solvent selected from the group consisting of an alcohol represented by formula (II), an ethylene glycol ether represented by formula (II) below, and a ketone represented by formula (III) below (component 2) The step of rinsing with an aqueous rinsing solution containing an amphoteric surfactant and / or an anionic surfactant and (component 3) water, wherein the crosslinked relief-forming layer comprises (component A A layer obtained by crosslinking a resin composition for laser engraving containing a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator by heat and / or light; Content is Characterized in that it is a 0.5 to 45% by weight, based on the total weight of sexual rinsing liquid, a method for making a flexographic printing plate,

〔式（Ｉ）中、Ｒ¹、Ｒ²及びＲ³はそれぞれ独立に水素原子、炭素数１〜３の直鎖アルキル基、又は、炭素数３〜４の分岐アルキル基を表し、Ｒ¹、Ｒ²及びＲ³の炭素数の合計は４〜５であり、式（ＩＩ）中、Ｘ及びＹはそれぞれ独立に水素原子又はメチル基を表し、Ｘ及びＹが共に水素原子のとき、Ｒ⁴はｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｒ⁵は水素原子、ｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｘ及びＹの一方が水素原子、もう一方がメチル基のとき、Ｒ⁴は炭素数３〜４の直鎖又は分岐アルキル基を表し、Ｒ⁵は水素原子若しくは炭素数３〜４の直鎖又は分岐アルキル基を表し、式（ＩＩＩ）中、Ｒ⁶及びＲ⁷はそれぞれ独立に炭素数１〜３のアルキル基を表し、Ｒ⁶及びＲ⁷の炭素数の合計は４〜６である。〕

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4 to 5, and in formula (II), X and Y each independently represent a hydrogen atom or a methyl group, and when both X and Y are hydrogen atoms, R ⁴ Represents an n-propyl group, an isopropyl group, or a branched butyl group, R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and one of X and Y is a hydrogen atom, When the other is a methyl group, R ⁴ represents a linear or branched alkyl group having 3 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms, and has the formula (III during) represents an alkyl group having 1 to 3 carbon atoms in R ⁶ and R ⁷ are independently, R ⁶ and R The total carbon number of ⁷ is 4-6. ]

<2> Component 1 is 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 4-methyl-2 -A method for making a flexographic printing plate according to <1>, which is a compound selected from the group consisting of pentanol, ethylene glycol mono-t-butyl ether, propylene glycol mono-n-butyl ether, diethyl ketone, and 2-pentanone,
<3> Component 1 is propylene glycol mono n-butyl ether or diethyl ketone, The plate making method of the flexographic printing plate as described in <2>,
<4> The method for making a flexographic printing plate according to any one of <1> to <3>, wherein the solubility of component 1 in water at 20 ° C. is 1.5 to 10.0 g / 100 ml,
<5> The method for making a flexographic printing plate according to any one of <1> to <4>, wherein Component 2 is an amphoteric surfactant represented by the following formula (IV) or the following formula (V): ,

〔式（ＩＶ）中、Ｒ⁸〜Ｒ¹⁰は、それぞれ独立に一価の有機基を表し、式（Ｖ）中、Ｒ¹¹〜Ｒ¹³は、それぞれ独立に一価の有機基を表し、Ｌは二価の連結基を表し、ＡはＣＯＯ又はＳＯ₃を表す。〕

[In Formula (IV), R ^{8 to} R ¹⁰ each independently represents a monovalent organic group, and in Formula (V), R ^{11 to} R ¹³ each independently represents a monovalent organic group; Represents a divalent linking group, and A represents COO or SO ₃ . ]

<6> The method for making a flexographic printing plate according to any one of <1> to <4>, wherein Component 2 is benzenesulfonate, naphthalenesulfonate, or sulfate ester salt,
<7> Component A is a styrenic thermoplastic elastomer, The plate making method of the flexographic printing plate as described in any one of <1>-<6>,
<8> A flexographic printing plate obtained by the plate making method of a flexographic printing plate according to any one of <1> to <7>,
<9> (Component 1) A group consisting of alcohols represented by the following formula (I), ethylene glycol ethers represented by the following formula (II), and ketones represented by the following formula (III) An organic solvent selected from (Component 2) an amphoteric surfactant and / or an anionic surfactant, and (Component 3) water, and the content of Component 1 is the total mass of the aqueous rinse liquid. Rinsing liquid for laser engraving-type flexographic printing plate, characterized by being 0.5 to 45% by mass based on

〔式（Ｉ）中、Ｒ¹、Ｒ²及びＲ³はそれぞれ独立に水素原子、炭素数１〜３の直鎖アルキル基、又は、炭素数３〜４の分岐アルキル基を表し、Ｒ¹、Ｒ²及びＲ³の炭素数の合計は４〜５であり、式（ＩＩ）中、Ｘ及びＹはそれぞれ独立に水素原子又はメチル基を表し、Ｘ及びＹが共に水素原子のとき、Ｒ⁴はｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｒ⁵は水素原子、ｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｘ及びＹの一方が水素原子、もう一方がメチル基のとき、Ｒ⁴は炭素数３〜４の直鎖又は分岐アルキル基を表し、Ｒ⁵は水素原子若しくは炭素数３〜４の直鎖又は分岐アルキル基を表し、式（ＩＩＩ）中、Ｒ⁶及びＲ⁷はそれぞれ独立に炭素数１〜３のアルキル基を表し、Ｒ⁶及びＲ⁷の炭素数の合計は４〜６である。〕

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4 to 5, and in formula (II), X and Y each independently represent a hydrogen atom or a methyl group, and when both X and Y are hydrogen atoms, R ⁴ Represents an n-propyl group, an isopropyl group, or a branched butyl group, R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and one of X and Y is a hydrogen atom, When the other is a methyl group, R ⁴ represents a linear or branched alkyl group having 3 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms, and has the formula (III during) represents an alkyl group having 1 to 3 carbon atoms in R ⁶ and R ⁷ are independently, R ⁶ and R The total carbon number of ⁷ is 4-6. ]

<10> Component 1 is 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 4-methyl-2 -Laser engraving-type flexographic printing plate according to <9>, which is a compound selected from the group consisting of pentanol, ethylene glycol mono t-butyl ether, propylene glycol mono n-butyl ether, diethyl ketone, and 2-pentanone Rinse solution,
<11> Component 1 is propylene glycol mono n-butyl ether or diethyl ketone, The rinse solution for laser engraving-type flexographic printing plates according to <10>,
The rinsing liquid for laser engraving-type flexographic printing plate according to any one of <9> to <11>, wherein the solubility of <12> component 1 in water at 20 ° C. is 1.5 to 10.0 g / 100 ml. ,
<13> A relief in which a resin composition for laser engraving containing (Component A) a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator is crosslinked by heat and / or light. A laser engraving mold comprising: a flexographic printing plate precursor for laser engraving having a forming layer; and a rinse liquid for a laser engraving flexographic printing plate according to any one of <9> to <12> Flexographic printing plate making kit.

  INDUSTRIAL APPLICABILITY According to the present invention, a laser engraving-type flexographic printing plate excellent in rinsing property of engraving residue generated by laser engraving and UV ink printing durability, a plate-making method thereof, a rinse solution for a laser engraving-type flexographic printing plate, and a laser engraving A flexographic printing plate making kit can be provided.

(Method for making flexographic printing plates)
The plate making method of the flexographic printing plate in the present invention includes a step of preparing a flexographic printing plate precursor for laser engraving having a crosslinked relief forming layer, a step of laser engraving the printing plate precursor in an image-like manner, an engraved surface, (Component 1) selected from the group consisting of alcohols represented by the following formula (I), ethylene glycol ethers represented by the following formula (II), and ketones represented by the following formula (III) A step of rinsing with an aqueous rinsing solution containing an organic solvent, (Component 2) an amphoteric surfactant, and / or an anionic surfactant, and (Component 3) water. A resin composition for laser engraving, wherein the relief forming layer contains (Component A) a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator, is heated and / or light-induced. A crosslinked layer, and the content of component 1 is 0.5 to 45% by weight, based on the total weight of the aqueous rinse solution.

〔式（Ｉ）中、Ｒ¹、Ｒ²及びＲ³はそれぞれ独立に水素原子、炭素数１〜３の直鎖アルキル基、又は、炭素数３〜４の分岐アルキル基を表し、Ｒ¹、Ｒ²及びＲ³の炭素数の合計は４〜５であり、式（ＩＩ）中、Ｘ及びＹはそれぞれ独立に水素原子又はメチル基を表し、Ｘ及びＹが共に水素原子のとき、Ｒ⁴はｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｒ⁵は水素原子、ｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｘ及びＹの一方が水素原子、もう一方がメチル基のとき、Ｒ⁴は炭素数３〜４の直鎖又は分岐アルキル基を表し、Ｒ⁵は水素原子若しくは炭素数３〜４の直鎖又は分岐アルキル基を表し、式（ＩＩＩ）中、Ｒ⁶及びＲ⁷はそれぞれ独立に炭素数１〜３のアルキル基を表し、Ｒ⁶及びＲ⁷の炭素数の合計は４〜６である。〕

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4 to 5, and in formula (II), X and Y each independently represent a hydrogen atom or a methyl group, and when both X and Y are hydrogen atoms, R ⁴ Represents an n-propyl group, an isopropyl group, or a branched butyl group, R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and one of X and Y is a hydrogen atom, When the other is a methyl group, R ⁴ represents a linear or branched alkyl group having 3 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms, and has the formula (III during) represents an alkyl group having 1 to 3 carbon atoms in R ⁶ and R ⁷ are independently, R ⁶ and R The total carbon number of ⁷ is 4-6. ]

  In this specification, regarding the description of the flexographic printing plate precursor, the component A, the component B and the component C are contained, and the surface is a flat layer as an image forming layer to be subjected to laser engraving, and is uncrosslinked. The crosslinkable layer is referred to as a relief forming layer, and a layer in which the relief forming layer is subjected to laser engraving after crosslinking to form irregularities on the surface is referred to as a relief layer. Further, the UV ink is an ultraviolet curable ink.

In the present invention, the description of “lower limit to upper limit” representing a numerical range represents “more than the lower limit and less than or equal to the upper limit”, and the description of “upper limit to lower limit” represents “the upper limit or less and less than the lower limit”. That is, it represents a numerical range including an upper limit and a lower limit. In the present invention, “(component A) thermoplastic elastomer” or the like is also simply referred to as “component A” or the like.
Hereinafter, the essential or optional constituent requirements regarding the plate making method of the laser engraving type flexographic printing plate will be described.

<Process for preparing a flexographic printing plate precursor for laser engraving>
The flexographic printing plate precursor for laser engraving used in the present invention (hereinafter also simply referred to as “flexographic printing plate precursor”) comprises a relief-forming layer obtained by crosslinking a resin composition for laser engraving described later with heat and / or light. Have.
A “flexographic printing plate” is produced by laser engraving a printing plate precursor having a relief forming layer.
In the present invention, the “relief layer” refers to a layer engraved by laser, that is, the relief forming layer after laser engraving.

  The flexographic printing plate precursor for laser engraving used in the present invention comprises the above relief forming layer and, if necessary, a support, an adhesive layer between the support and the relief forming layer, a cover film or slip coat on the relief forming layer. It may have a layer.

[Relief forming layer]
The relief forming layer is a layer in a state before cross-linking made of a resin composition for laser engraving described later, and may be dried if necessary.

  As a production mode of a flexographic printing plate using a flexographic printing plate precursor for laser engraving, a relief layer is formed by laser engraving a relief forming layer to produce a flexographic printing plate. Since the relief forming layer is crosslinked, wear of the relief layer during printing can be prevented, and a flexographic printing plate having a relief layer having a sharp shape after laser engraving can be obtained.

The relief forming layer can be formed by molding a resin composition for laser engraving having the following components for the relief forming layer into a sheet shape or a sleeve shape. The relief forming layer is usually provided on a support which will be described later. However, the relief forming layer can be directly formed on the surface of a member such as a cylinder provided in an apparatus for plate making and printing, or can be arranged and fixed there. It does not necessarily require a support.
Hereinafter, the case where the relief forming layer is formed into a sheet shape will be mainly described as an example.

[Support]
The material used for the support of the flexographic printing plate precursor for laser engraving is not particularly limited, but materials having high dimensional stability are preferably used. For example, metals such as steel, stainless steel, aluminum, polyester (for example, PET (polyethylene terephthalate)) , PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PAN (polyacrylonitrile)), polyvinyl chloride and other plastic resins, styrene-butadiene rubber, nitrile-butadiene rubber, ethylene propylene rubber, butyl rubber and other synthetic rubbers And plastic resins reinforced with glass fibers (such as epoxy resins and phenol resins). As the support, a PET film or a steel substrate is preferably used. The form of the support is determined depending on whether the relief forming layer is a sheet or a sleeve.

(Adhesive layer)
When the relief forming layer is formed on the support, it may be directly laminated, but an adhesive layer may be provided between them for the purpose of enhancing the adhesive strength between the layers.
Examples of materials (adhesives) that can be used for the adhesive layer include: Those described in the edition of Skeist, “Handbook of Adhesives”, the second edition (1977) can be used.

[Cover film, slip coat layer]
A cover film may be provided on the relief forming layer for the purpose of preventing scratches and dents on the surface of the relief forming layer. The thickness of the cover film is preferably 25 to 500 μm, more preferably 50 to 200 μm. As the cover film, for example, a polyester film such as PET, or a polyolefin film such as PE (polyethylene) or PP (polypropylene) can be used. The surface of the cover film may be matted. The cover film is peeled off before engraving or printing.
If the cover film is difficult to peel off, or conversely difficult to adhere to the relief forming layer, a slip coat layer may be provided between both layers. The material used for the slip coat layer is a resin that can be dissolved or dispersed in water, such as polyvinyl alcohol, polyvinyl acetate, partially saponified polyvinyl alcohol, hydroxyalkyl cellulose, alkyl cellulose, polyamide resin, etc. It is preferable that

[Method of manufacturing flexographic printing plate precursor for laser engraving]
The method for producing a flexographic printing plate precursor for laser engraving in the present invention includes a layer forming step of forming a resin composition for laser engraving in the present invention as a layer described later, and a crosslinking step of crosslinking the resin composition to form a relief forming layer. It is preferable that it is a manufacturing method containing these.

Thereafter, a cover film may be laminated on the relief forming layer as necessary. Lamination can be performed by pressure-bonding the cover film and the relief forming layer with a heated calendar roll or the like, or by bringing the cover film into close contact with the relief forming layer impregnated with a small amount of solvent on the surface.
When a cover film is used, a method of first laminating a relief forming layer on the cover film and then laminating the support may be employed.
When providing an adhesive layer, it can respond by using the support body which apply | coated the adhesive layer. When the slip coat layer is provided, it can be dealt with by using a cover film coated with the slip coat layer.

[Layer formation process]
The method for producing a laser engraving-type flexographic printing plate precursor according to the present invention preferably includes a layer forming step of forming a relief forming layer comprising a resin composition for laser engraving described later.
As a method for forming the relief forming layer, the resin composition for laser engraving of the present invention is prepared, and if necessary, after removing the solvent from the resin composition for laser engraving, a method of melt extrusion on a support, A method of preparing the resin composition for laser engraving of the present invention, casting the resin composition for laser engraving of the present invention on a support and drying it in an oven to remove the solvent is preferably exemplified.

  The thickness of the relief forming layer in the flexographic printing plate precursor for laser engraving is preferably 0.05 to 10 mm, preferably 0.1 to 5 mm, from the viewpoint of satisfying various printability such as abrasion resistance and ink transferability. Is more preferable, and 0.3-2 mm is still more preferable.

[Crosslinking process]
The method for producing a flexographic printing plate precursor for laser engraving of the present invention is preferably a production method including a crosslinking step for obtaining a flexographic printing plate precursor having a relief forming layer obtained by crosslinking the relief forming layer with heat and / or light. More preferably, the production method includes a crosslinking step of obtaining a flexographic printing plate precursor having a relief forming layer obtained by crosslinking the relief forming layer with heat.
The relief forming layer can be crosslinked by heating the flexographic printing plate precursor for laser engraving (thermal crosslinking step). Examples of the heating means for crosslinking by heat include a method of heating the printing plate precursor in a hot air oven or a far infrared oven for a predetermined time, and a method of contacting a heated roll for a predetermined time.
By thermally crosslinking the relief forming layer, there is an advantage that, firstly, the relief formed after laser engraving becomes sharp, and secondly, the adhesiveness of engraving residue generated during laser engraving is suppressed.

Moreover, in order to form a bridge | crosslinking by polymerizing a polymeric compound using a photoinitiator etc., you may further perform bridge | crosslinking by light.
When the relief-forming layer contains a photopolymerization initiator, the relief-forming layer is crosslinked by irradiating the relief-forming layer with light that triggers the photopolymerization initiator (also referred to as “active light”). Can do.
In general, light is applied to the entire surface of the relief forming layer. Examples of light include visible light, ultraviolet light, and electron beam, but ultraviolet light is the most common. If the substrate side for immobilizing the relief forming layer, such as the support of the relief forming layer, is the back side, the surface may only be irradiated with light, but the support should be a transparent film that transmits actinic rays. For example, it is preferable to irradiate light from the back side. When the protective film exists, the irradiation from the surface may be performed while the protective film is provided, or may be performed after the protective film is peeled off. Since polymerization inhibition may occur in the presence of oxygen, irradiation with actinic rays may be performed after the relief forming layer is covered with a polyvinyl chloride sheet and evacuated.

<Process of laser engraving flexographic printing plate precursor imagewise>
The plate making method of the flexographic printing plate in the present invention includes a step of laser-engraving the flexographic printing plate precursor having the relief forming layer imagewise (hereinafter also simply referred to as “engraving step”).
The engraving step is a step of forming a relief layer by laser engraving the relief forming layer. Specifically, it is preferable to form the relief layer by engraving the relief forming layer by irradiating a laser beam corresponding to a desired image. Further, a step of controlling the laser head with a computer based on digital data of a desired image and performing scanning irradiation on the relief forming layer is preferable.
In this engraving process, an infrared laser is preferably used. When irradiated with an infrared laser, the molecules in the relief forming layer undergo molecular vibrations and generate heat. When a high-power laser such as a carbon dioxide laser or a YAG laser is used as an infrared laser, a large amount of heat is generated in the laser irradiation portion, and molecules in the relief forming layer are selectively cut by molecular cutting or ionization, that is, Sculpture is made. The advantage of laser engraving is that since the engraving depth can be set arbitrarily, the structure can be controlled three-dimensionally. For example, a portion that prints fine halftone dots can be engraved shallowly or with a shoulder so that the relief does not fall down due to printing pressure, and a portion of a groove that prints fine punched characters is engraved deeply As a result, the ink is less likely to be buried in the groove, and it is possible to suppress the crushing of the extracted characters.
In particular, when engraving with an infrared laser corresponding to the absorption wavelength of the photothermal conversion agent, the relief forming layer can be selectively removed with higher sensitivity, and a relief layer having a sharp image can be obtained.

As the infrared laser used in the engraving process, a carbon dioxide laser (CO ₂ laser) or a semiconductor laser is preferable from the viewpoints of productivity and cost. In particular, a semiconductor infrared laser with a fiber (FC-LD) is preferably used. In general, a semiconductor laser can be downsized with high efficiency and low cost of laser oscillation compared to a CO ₂ laser. Moreover, since it is small, it is easy to form an array. Furthermore, the beam shape can be controlled by processing the fiber.
The semiconductor laser preferably has a wavelength of 700 to 1,300 nm, more preferably 800 to 1,200 nm, still more preferably 860 to 1,200 nm, and particularly preferably 900 to 1,100 nm.

Since a semiconductor laser with a fiber can output a laser beam efficiently by attaching an optical fiber, it is effective for the engraving process in the present invention. Furthermore, the beam shape can be controlled by processing the fiber. For example, the beam profile can have a top hat shape, and energy can be stably given to the plate surface. Details of the semiconductor laser are described in “Laser Handbook 2nd Edition” edited by the Laser Society, practical laser technology, and the Institute of Electronics and Communication Engineers of Japan.
In addition, a plate making apparatus equipped with a fiber-coupled semiconductor laser that can be suitably used for the plate making method of a flexographic printing plate according to the present invention is described in detail in JP-A-2009-172658 and JP-A-2009-214334. Can be used for making a flexographic printing plate according to the present invention.

<Rinsing the engraved surface>
In the present invention, after the step of laser-engraving the flexographic printing plate precursor for laser engraving as described above, the step of rinsing the engraved surface (hereinafter also simply referred to as “rinsing step”) is essential. .
The time interval from the engraving to the rinsing step (the time from when a certain point of the relief forming layer is engraved until the same portion comes into contact with the rinsing liquid) is not particularly limited, but is preferably shorter. This is because the engraving residue remaining on the plate gradually aggregates or the rinsing property tends to be lowered when time passes without rinsing after engraving. It is preferable to rinse on the same day as the engraving, more preferably within 2 hours after engraving, and even more preferably within 1 hour.

[Rinsing solution for laser engraving flexographic printing plates]
The rinsing liquid for laser engraving-type flexographic printing plate in the present invention (hereinafter referred to as “the rinsing liquid of the present invention”) includes (Component 1) an organic solvent having a specific structure, (Component 2) an amphoteric surfactant, and / or , An anionic surfactant, and an aqueous rinse liquid containing (Component 3) water, and the component 1 is dissolved in the water of the component 3 or is dissolved in the single phase (solubilized by the component 2). Not aqueous solution or aqueous dispersion.
Component 1 is the main agent responsible for the removal of engraving residue. However, when component 1 is used alone as a rinsing liquid, the solvent odor is very strong and the environment at the plate making site is deteriorated. In order to reduce the exposure of the solvent on the surface, the rinsing liquid of the present invention is used by being mixed with (Component 3) water or solubilized with (Component 2) a surfactant.
At this time, if an organic solvent that is extremely compatible with water is used, it can exist stably in water, so even if the rinsing liquid is brought into contact with the engraving residue, the organic solvent does not easily penetrate into the engraving residue and the rinsing property is insufficient. It becomes. Therefore, as the component 1, the structure of the present invention is required, and it is more preferable that the solubility in water at 20 ° C. is 1.5 to 10.0 g / 100 ml. As a result, the solvent odor can be greatly reduced, and when it comes into contact with the engraving residue, the oil-in-water micelles are destroyed, so that the organic solvent that is the developing agent penetrates into the engraving residue and removes the residue. It becomes possible. In addition, it is considered that the component 2 itself in the present invention also has a function of promoting the penetration of the rinse liquid into the engraving residue and promoting the removal of residue.
Hereinafter, the components of the rinse liquid of the present invention will be described.

(Component 1) Organic solvent having a specific structure The rinsing liquid of the present invention contains, as Component 1, an alcohol represented by the following formula (I), an ethylene glycol ether represented by the following formula (II), and the following formula: It contains an organic solvent selected from the group consisting of ketones represented by (III).

〔式（Ｉ）中、Ｒ¹、Ｒ²及びＲ³はそれぞれ独立に水素原子、炭素数１〜３の直鎖アルキル基、又は、炭素数３〜４の分岐アルキル基を表し、Ｒ¹、Ｒ²及びＲ³の炭素数の合計は４〜５であり、式（ＩＩ）中、Ｘ及びＹはそれぞれ独立に水素原子又はメチル基を表し、Ｘ及びＹが共に水素原子のとき、Ｒ⁴はｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｒ⁵は水素原子、ｎ−プロピル基、イソプロピル基、又は、分岐したブチル基を表し、Ｘ及びＹの一方が水素原子、もう一方がメチル基のとき、Ｒ⁴は炭素数３〜４の直鎖又は分岐アルキル基を表し、Ｒ⁵は水素原子若しくは炭素数３〜４の直鎖又は分岐アルキル基を表し、式（ＩＩＩ）中、Ｒ⁶及びＲ⁷はそれぞれ独立に炭素数１〜３のアルキル基を表し、Ｒ⁶及びＲ⁷の炭素数の合計は４〜６である。〕

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4 to 5, and in formula (II), X and Y each independently represent a hydrogen atom or a methyl group, and when both X and Y are hydrogen atoms, R ⁴ Represents an n-propyl group, an isopropyl group, or a branched butyl group, R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and one of X and Y is a hydrogen atom, When the other is a methyl group, R ⁴ represents a linear or branched alkyl group having 3 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms, and has the formula (III during) represents an alkyl group having 1 to 3 carbon atoms in R ⁶ and R ⁷ are independently, R ⁶ and R The total carbon number of ⁷ is 4-6. ]

Examples of the alcohol represented by the formula (I) include 2,2-dimethyl-1-propanol (neopentyl alcohol), 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-methyl-2- Butanol, 3-methyl-2-butanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-2-butanol, 2-pentanol, 2-methyl-2-pentanol, 3-methyl-2- Examples include pentanol, 4-methyl-2-pentanol, 4-methyl-2-pentanol, 3-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, and 3-hexanol. .
Among these, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and neopentyl alcohol are more preferable.

Examples of the ethylene glycol ether represented by the formula (II) include ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono sec-butyl ether, ethylene glycol mono t-butyl ether, propylene Glycol mono n-propyl ether, propylene glycol mono isopropyl ether, propylene glycol mono n-butyl ether, propylene glycol mono isobutyl ether, propylene glycol mono sec-butyl ether, propylene glycol mono t-butyl ether monoethers, ethylene glycol di n- Propyl ether, ethylene glycol diisopropyl ether, ethylene glycol Diisobutyl ether, ethylene glycol di sec-butyl ether, ethylene glycol di t-butyl ether, propylene glycol di n-propyl ether, propylene glycol diisopropyl ether, propylene glycol di n-butyl ether, propylene glycol diisobutyl ether, propylene glycol di sec-butyl ether, propylene And diethers of glycol di-t-butyl ether.
Among these, ethylene glycol monoisopropyl ether, ethylene glycol mono t-butyl ether, propylene glycol mono n-butyl ether, and propylene glycol mono t-butyl ether are more preferable, and ethylene glycol mono t-butyl ether and propylene glycol mono n-butyl ether are still more preferable.

Examples of the ketones represented by the formula (III) include 3-methyl-2-butanone, 2-pentanone, diethyl ketone, 2-methyl-3-pentanone, 2,4-dimethyl-3-pentanone, 3-hexanone, Examples include 2-methyl-3-hexanone and 4-heptanone.
Among these, 2-pentanone and diethyl ketone are more preferable, and diethyl ketone is still more preferable.

Component 1 used in the rinsing solution of the present invention preferably has a water solubility at 20 ° C. in the range of 1.5 to 10.0 g / 100 ml. The solubility of these organic solvents in water generally varies depending on the temperature, but in the temperature range of 5 to 40 ° C. where the liquid temperature of the rinsing liquid may vary depending on the external environment, it does not vary dramatically. In addition, since the effect is almost the same as long as the temperature is within this temperature range, a preferable range is defined by the solubility at 20 ° C. generally used in the present application.
Hereinafter, preferred organic solvents as component 1 are exemplified. The parentheses after the name of the organic solvent represent the solubility in water at 20 ° C.
For example, 2,2-dimethyl-1-propanol (3.5 g / 100 ml), 2-methyl-1-butanol (3.0 g / 100 ml), 3-methyl-1-butanol (2.7 g / 100 ml), 3 -Methyl-2-butanol (5.6 g / 100 ml), 2-pentanol (4.5 g / 100 ml), 3-pentanol (5.2 g / 100 ml), 4-methyl-2-pentanol (2.0 g) / 100 ml), propylene glycol mono n-butyl ether (4.4 g / 100 ml), 2-pentanone (4.0 g / 100 ml), diethyl ketone (1.7 g / 100 ml).
Ethylene glycol mono n-butyl ether (miscible with water) or ethylene glycol mono n-hexyl ether (1.0 g / 100 ml), which has the same structure as component 1 used in the rinsing liquid of the present invention but has not been effective. ) Is presumed to be affected by this physical property. However, there are exceptions of ethylene glycol mono-t-butyl ether (mixed in water) in which the effect of the present invention was recognized and 4-methyl-2-pentanone (1.9 g / 100 ml) in which the effect was not recognized. Only does not contribute to the effect of the present invention.

  Component 1 includes 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 4-methyl-2-pent It is preferably a compound selected from the group consisting of tanol, ethylene glycol mono t-butyl ether, propylene glycol mono n-butyl ether, diethyl ketone, and 2-pentanone, and 3-pentanol, 3-methyl-2-butanol More preferably a compound selected from the group consisting of ethylene glycol mono-t-butyl ether, propylene glycol mono-n-butyl ether, and diethyl ketone, and further being propylene glycol mono-n-butyl ether or diethyl ketone. preferable.

As component 1 used in the rinse liquid of the present invention, the above organic solvents may be used alone or in combination of two or more.
The usage-amount of the component 1 in this invention is 0.5-45 mass% with respect to the total mass of a rinse liquid. When the amount is less than 0.5% by mass, the effect of the present invention is not recognized. It is more preferably 1 to 35% by mass, and further preferably 3 to 25% by mass.
Moreover, it is preferable that content with respect to the (component 3) water of the component 1 in a rinse liquid exceeds the solubility to the water of the component 1 in 20 degreeC. The rinse liquid of the present invention contains (Component 2) an amphoteric surfactant and / or an anionic surfactant, so that the component 1 exceeds the solubility in the rinse liquid without being separated into two phases. Can be contained. In the case of the above aspect, when the rinsing liquid comes into contact with the engraving residue, the developing agent component 1 permeates into the engraving residue by destroying the oil in water micelles. Guessed.

(Component 2) Amphoteric surfactant and / or anionic surfactant The rinse liquid of the present invention contains (Component 2) an amphoteric surfactant and / or an anionic surfactant. Thereby, it becomes possible for the component 1 and water to be stably mixed, and the removability improvement of the engraving residue and the dispersion stability of the removed residue in the rinse liquid are improved.

  As the amphoteric surfactant used in Component 2, known ones can be used without limitation, but betaine surfactants, amine oxide surfactants, phosphine oxide surfactants, or amino acid surfactants Activators are preferred, carboxybetaine surfactants, sulfobetaine surfactants, phosphobetaine surfactants, amine oxide surfactants, and phosphine oxide surfactants, more preferred are the following formulas (IV) and / or Or the compound represented by following formula (V) is still more preferable.

〔式（ＩＶ）中、Ｒ⁸〜Ｒ¹⁰は、それぞれ独立に一価の有機基を表し、式（Ｖ）中、Ｒ¹¹〜Ｒ¹³は、それぞれ独立に一価の有機基を表し、Ｌは二価の連結基を表し、ＡはＣＯＯ又はＳＯ₃を表す。〕、

[In Formula (IV), R ^{8 to} R ¹⁰ each independently represents a monovalent organic group, and in Formula (V), R ^{11 to} R ¹³ each independently represents a monovalent organic group; Represents a divalent linking group, and A represents COO or SO ₃ . ],

Although there is no restriction | limiting in particular as a monovalent organic group in R < ⁸ > -R < ¹⁰ >, R < ¹¹ > -R < ¹³ > in Formula (IV) and (V), In an alkyl group, the alkyl group which has a hydroxy group, and an alkyl chain It is preferably an alkyl group having an amide bond, or an alkyl group having an ether bond in the alkyl chain, and is an alkyl group, an alkyl group having a hydroxy group, or an alkyl group having an amide bond in the alkyl chain. Is more preferable.
In addition, the alkyl group in the monovalent organic group may be linear, branched, or have a ring structure.
Two of R ^{8 to} R ¹⁰ and two of R ^{11 to} R ¹³ are methyl groups, that is, the compounds represented by the formulas (IV) and (V) are N, N-dimethyl. It is particularly preferable to have a structure.

L in the above formula (V) is a divalent linking group and is not particularly limited, but is preferably an alkylene group or an alkylene group having a hydroxy group, an alkylene group having 1 to 8 carbon atoms, or And more preferably an alkylene group having 1 to 8 carbon atoms having a hydroxy group, and further preferably an alkylene group having 1 to 3 carbon atoms or an alkylene group having 1 to 3 carbon atoms having a hydroxy group.
A in Formula (V) is more preferably a carboxylate ion.

  Specific examples of the compound represented by the above formula (IV) include the following.

  Specific examples of the compound represented by the formula (V) include the following.

  As the anionic surfactant used for Component 2, a known one can be used without limitation, but a sulfonate compound or a sulfate ester compound is preferable, and a benzenesulfonate, naphthalenesulfonate, Or a sulfate ester compound is more preferable, and a benzenesulfonate or naphthalenesulfonate is still more preferable.

  The benzene sulfonate and naphthalene sulfonate may have a substituent on the benzene ring. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a linear, branched or cyclic alkyl group (eg, a methyl group, an ethyl group, a propyl group), an alkenyl group, an alkynyl group, Aryl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, cyano group, carboxyl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, heterocyclic oxy group, acyloxy group, amino group, nitro group, And heterocyclic groups. Moreover, these substituents may be further substituted with the above substituents. Preferably, it is an alkyl group, an alkyloxy group, or an aryloxy group, and more preferably an alkyl group.

  Examples of the sulfate ester compounds include alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, polyoxyethylene aryl ether sulfate esters, polyoxyethylene alkyl phenyl ether sulfate esters, polyoxyethylene polycyclic phenyl ether sulfate esters. Salt, fatty acid monoglyceride sulfate, polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene styryl phenyl ether sulfate, polyoxyethylene aryl ether sulfate, or polyoxyethylene alkylphenyl ether sulfate A salt is preferable, and a polyoxyethylene aryl ether sulfate salt is more preferable. The aryl group of the polyoxyethylene aryl ether sulfate ester salt is preferably a naphthyl group.

  The sulfate ester compound may have the above substituent on the aromatic ring of the alkyl group or aryl group. Moreover, these substituents may be further substituted with the above substituents. Of the above substituents, an alkyl group, an alkyloxy group, or an aryloxy group is preferable, and an alkyl group is more preferable.

  Specific examples of the benzene sulfonate include the following.

  Specific examples of naphthalene sulfonate include the following.

  Specific examples of the sulfate ester salt include the following.

  As component 2 used in the rinse liquid of the present invention, the above surfactants may be used alone or in combination of two or more. The amount of component 2 used is not particularly limited, but is preferably 0.03 to 25% by mass, more preferably 0.05 to 20%, based on the total mass of the rinsing liquid. More preferably, it is -15 mass%, and it is especially preferable that it is 1-12 mass%.

  The molecular weight of Component 2 is preferably 100 to 3,000, more preferably 150 to 2,000, and still more preferably 200 to 1,500.

(Component 3) Water The rinse liquid of the present invention contains (Component 3) water as an essential component.
As the water, any water such as tap water, ground water, industrial water, ion exchange water, distilled water, reverse osmosis water, activated carbon or water treated with a general household water purifier can be used.
The content of Component 3 is not particularly limited, but is preferably 45 to 99% by mass, more preferably 60 to 97% by mass, and 70 to 95% by mass with respect to the total mass of the rinse liquid. % Is more preferable.

  The total content of component 1, component 2 and component 3 is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass. .

≪Other additives≫
As long as the effects of the present invention are not impaired, various compounds can be added to the rinsing liquid of the present invention in accordance with the purpose. For example, a pH adjuster, an antifoaming agent, an antiseptic, a fragrance, a coloring agent, and the like can be given.

≪pH adjuster≫
The pH of the rinsing solution that can be used in the present invention is not particularly limited, but is preferably 6 or more, more preferably 6.5 or more, and still more preferably 7.0 or more. Moreover, it is preferable that the pH of a rinse liquid is 14 or less, It is more preferable that it is 13 or less, It is still more preferable that it is 12.5 or less. Handling is easy in the said range. What is necessary is just to adjust pH using an acid and / or a base suitably as a pH adjuster in order to make a rinse solution into said pH range, and the pH adjuster to be used is not specifically limited.

≪Defoamer≫
The rinse liquid of the present invention may contain an antifoaming agent.
As the antifoaming agent, a surfactant that does not correspond to Component 2 can be used. For example, a general silicone-based antifoaming agent, a compound such as a nonionic surfactant having an HLB (Hydrophile-Lipophile Balance) value of 5 or less can be used, and a silicone-based antifoaming agent is preferable. As long as it is a silicone type antifoaming agent, any of an emulsified dispersion type and a solubilized type may be used.
Specific examples of the antifoaming agent include TSA 731 and TSA 739 (manufactured by Toray Dow Corning Co., Ltd.).
The content of the antifoaming agent is preferably 0.001 to 1.0% by mass with respect to the total amount of the rinsing liquid.
Moreover, it is preferable that it is 0.1-30 mass%, as for content with respect to the component 2 of an antifoamer, it is more preferable that it is 0.2-10 mass%, and it is 0.2-5 mass%. More preferably.

≪Preservatives≫
The rinse liquid of the present invention may contain a preservative.
Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzoisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, benztriazole derivatives Amiding anidine derivatives, quaternary ammonium salts, derivatives such as pyridine, quinoline, guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3-diol, 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used. It is preferable to use two or more kinds of preservatives in combination so as to be effective against various molds and sterilization.
The content of the preservative is an amount that exerts stability against bacteria, molds, yeasts, etc., and varies depending on the type of bacteria, molds, yeasts, but 0.01% with respect to the total amount of the rinse solution. A range of ˜4 mass% is preferred.

  The rinsing liquid of the present invention may be prepared at the liquid concentration used in the rinsing step, or prepared as a concentrated liquid and diluted with water (component 3) so as to have a prescribed concentration during use. Also good. The latter is preferable in terms of transportation and storage of the rinse liquid.

  As a method of rinsing an engraved flexographic printing plate using the rinsing liquid of the present invention, a method of manually applying a rinsing liquid to the surface of the relief layer and rubbing it manually with a horse hair brush or nonwoven fabric, photosensitivity A method using a known batch type or conveying type brush type washing machine as a resin letterpress developing machine, a method of spraying a rinsing liquid at a high pressure, a method of ultrasonic cleaning with a flexographic printing plate immersed in a rinsing liquid, etc. Although it is mentioned, it is not limited to these.

<Other processes>
After the rinsing step, it is preferable to add a drying step for drying the engraved and rinsed relief layer to volatilize the rinsing liquid.
Furthermore, you may add the post-crosslinking process which further bridge | crosslinks a relief layer as needed. By performing this step, which is additional crosslinking, the relief formed by engraving can be strengthened.

As described above, a flexographic printing plate having a desired image-like relief can be obtained.
The Shore A hardness of the relief layer of the flexographic printing plate is preferably 50 to 90 °. When the Shore A hardness of the relief layer is 50 ° or more, the fine halftone dots formed by engraving will not collapse even if subjected to the strong printing pressure of the flexographic printing machine, and normal printing can be performed. Further, if the Shore A hardness of the relief layer is 90 ° or less, it is possible to prevent print fading (imperfect ink deposition) at the solid portion. Shore A hardness is measured with a durometer (spring type rubber hardness tester) that measures the amount of deformation (indentation depth) by pressing an indenter (called a push needle or indenter) into the surface of the object to be measured. I can do it.

  Hereinafter, the resin composition for laser engraving forming the relief layer in the present invention will be described.

  The resin composition for laser engraving in the present invention comprises (Component A) a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator.

(Resin composition for laser engraving)
(Component A) Thermoplastic Elastomer The resin composition in the present invention contains (Component A) a thermoplastic elastomer as an essential component. A thermoplastic elastomer is a material that plasticizes and flows at high temperatures and exhibits rubber elasticity at normal temperatures. Thermoplastic elastomers form a finely dispersed multiphase structure at room temperature. In most thermoplastic elastomers, the phases are chemically bonded by block copolymerization or graft copolymerization. When there is no chemical bond, a sufficiently fine dispersion state is formed. Component A is preferably a thermoplastic elastomer in which the phases are chemically bonded, and more preferably a block copolymer. The molecular structure of the block copolymer is composed of a soft segment such as polyether or rubber molecule and a hard segment that does not show plastic deformation at around room temperature like vulcanized rubber. Then, a multiphase structure in which the hard segment phase and the soft segment phase are finely dispersed is formed. There are various types of phases formed by the hard segment, such as a frozen phase, a crystalline phase, hydrogen bonding, and ionic crosslinking.

  Such a thermoplastic elastomer exhibits rubber elasticity at room temperature. Therefore, the ink can be deformed according to the unevenness of the printed material at the time of printing, so that the ink deposition property is excellent, and after leaving the printed material, the original shape is restored, so that the printing durability is excellent. Furthermore, since the thermoplastic elastomer exhibits fluidity when heated, handling such as mixing of materials is easy. For the above reasons, the thermoplastic elastomer is suitable when the resin composition for laser engraving in the present invention is applied to the production of relief printing plates that require flexibility such as flexographic plates.

From the viewpoint of printing durability and hardness of the relief printing plate, the proportion of the hard segment in the thermoplastic elastomer is preferably 10 to 70% by mass, and preferably 15 to 60% by mass.
Thermoplastic elastomer has a glass transition temperature (Tg) from the viewpoint of flexibility and rubber elasticity.
Is preferably a polymer having a temperature of 20 ° C. or lower, more preferably a polymer having a temperature of 0 ° C. or lower. From the viewpoint of printing durability, the thermoplastic elastomer is preferably a polymer having a melting point (Tm) of 70 ° C. or higher, and more preferably a polymer of 100 ° C. or higher.

  Thermoplastic elastomers include styrene thermoplastic elastomers, olefin thermoplastic elastomers, urethane thermoplastic elastomers, ester thermoplastic elastomers, amide thermoplastic elastomers, ethylene- (meth) acrylate thermoplastic elastomers, silicones -Based thermoplastic elastomers, PVC-based thermoplastic elastomers, nitrile-based thermoplastic elastomers, fluorine-based thermoplastic elastomers, chlorinated polyethylene cross-linked bodies, etc., among others, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, urethanes -Based thermoplastic elastomers and ester-based thermoplastic elastomers are preferred, and styrene-based thermoplastic elastomers are the most resistant to UV inks and rinse engraving residue with the rinsing liquid of the present invention described later. Preferred for bets becomes excellent.

  The reason why the styrenic thermoplastic elastomer is most preferable is that the higher the hydrophobicity of the soft segment, the better the UV ink resistance, while the relatively weak the cohesion of the hard segment, the better the rinsing property. As the latter mechanism, it is considered that the main component of engraving residue is a decomposition aggregate of hard segments, and the weaker this cohesion, the easier the rinsing liquid of the present invention penetrates and the easier it is to dissolve and disperse. It is estimated to be.

(Component A-1) Styrenic Thermoplastic Elastomer As the styrene thermoplastic elastomer, a polymer block (hard segment) mainly composed of monomer units derived from styrene monomers and a monomer unit derived from conjugated diene compounds are mainly used. And a block copolymer with a block (soft segment) and a hydrogenated monomer unit derived from a conjugated diene compound of the block copolymer.
Styrene monomers include styrene and at least one substituent (halogen atom (
F, Cl, Br, I), an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms)
The styrene derivative substituted by arbitrary positions by is mentioned. Specifically, styrene, α
-Methylstyrene, vinyltoluene or t-butylstyrene are mentioned, and among them, styrene is preferable.
Examples of the conjugated diene compound include butadiene, isoprene, chloroprene, and 2,3-dimethylbutadiene. Of these, butadiene and isoprene are preferable.
These may use only 1 type and may use it in combination of 2 or more type.
Specific examples of the styrenic thermoplastic elastomer include styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-ethylene / butylene-styrene copolymer (SEBS), Examples thereof include styrene-ethylene / propylene-styrene copolymer (SEPS) and styrene-ethylene-ethylene / propylene-styrene copolymer (SEEPS), among which SIS, SBS, and SEBS are preferable.

(Component A-2) Olefin-based thermoplastic elastomer The olefin-based thermoplastic elastomer is one in which a polyolefin resin that is a hard segment and an olefin-based elastomer that is a soft segment form multiple phases.
As the polyolefin which is a hard segment, polyethylene and polypropylene are preferable.
As the olefin elastomer that is a soft segment, a copolymer composed of a monomer unit derived from ethylene and a structural unit derived from an α-olefin unit having 3 or more carbon atoms is more preferable.
Examples of the α-olefin having 3 or more carbon atoms include propylene, 1-butene, 2-methyl-1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, Examples thereof include structural units derived from α-olefins such as 1-octene, 1-decene and 1-octadecene.
Specific examples of olefin elastomers include ethylene-propylene random copolymer, ethylene-butene random copolymer, ethylene-hexene random copolymer, ethylene-octene random copolymer, ethylene-decene random copolymer, ethylene- Examples include 4-methylpentene random copolymers, and ethylene-propylene random copolymers and ethylene-butene random copolymers are particularly preferable.
The olefin-based thermoplastic elastomer is preferably produced by so-called dynamic crosslinking in which a thermoplastic resin serving as a hard segment and an elastomer serving as a soft segment are melt-mixed and crosslinked. This is because, in a microphase-separated structure in which a discontinuous phase of rubber exists in the continuous phase of thermoplastic resin, dynamic crosslinking can reduce the domain size of the discontinuous phase of rubber. This is because it becomes a thermoplastic elastomer having a large elongation.

(Component A-3) Urethane-based thermoplastic elastomer The urethane-based thermoplastic elastomer has a hard segment composed of diisocyanate and short-chain glycol and a soft segment composed of diisocyanate and long-chain polyol.
Examples of the short chain glycol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, and the like.
Long chain polyols include poly (alkylene oxide) glycols (e.g., polyethylene glycol, poly (1, 2 and 1,3 propylene oxide) glycol, poly (tetramethylene oxide) glycol, poly ( Polyethers such as hexamethylene oxide) glycol) or polyesters such as polyalkylene adipate, polycaprolactone, polycarbonate, etc. are used.
Examples of the diisocyanate compound include phenylene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), 4,4′-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IpDI). Things are used.

(Component A-4) Ester Thermoplastic Elastomer As the ester thermoplastic elastomer, (1) an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, and (2) an aromatic dicarboxylic acid or an alkyl ester thereof. And (3) Polyalkylene ether glycol having a weight average molecular weight of 400 to 6,000 as a raw material, and obtained by polycondensation of an oligomer obtained by esterification reaction or transesterification reaction.

  As aliphatic and / or alicyclic diols having 2 to 12 carbon atoms used in the present invention, those known as raw materials for polyesters, particularly polyester elastomers, can be used, such as ethylene glycol, propylene glycol, Examples include methylene glycol, 1,4-butanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and the like, preferably 1,4-butanediol, ethylene glycol, particularly preferably 1,4-butane. A diol is the main component, and one or more can be used.

  As the aromatic dicarboxylic acid, known raw materials for polyester, particularly polyester elastomer, can be used, and examples thereof include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and the like. Terephthalic acid and 2,6-naphthalenedicarboxylic acid, particularly preferably terephthalic acid is the main component, and two or more of these may be used in combination. Examples of the alkyl ester of aromatic dicarboxylic acid include dimethyl esters such as dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, and 2,6-dimethyl naphthalate, preferably dimethyl terephthalate and 2,6-dimethyl naphthalate. In particular, dimethyl terephthalate is preferable, and two or more of these can be used in combination. In addition to the above, trifunctional diols, other diols and other dicarboxylic acids and esters thereof may be copolymerized in small amounts, and aliphatic or alicyclic dicarboxylic acids such as adipic acid, or alkyls thereof. Esters may also be used as copolymerization components.

  As the polyalkylene ether glycol, those having a weight average molecular weight of 400 to 6,000 are used, preferably 500 to 4,000, particularly preferably 600 to 3,000. If the molecular weight is less than 400, the block property of the copolymer is insufficient, and if the weight average molecular weight exceeds 6,000, the physical properties of the polymer are lowered due to phase separation in the system. Here, as polyalkylene ether glycol, polyethylene glycol, poly (1,2 and 1,3 propylene ether) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, block or random copolymer of ethylene oxide and propylene oxide And a block or random copolymer of ethylene oxide and tetrahydrofuran. Particularly preferred is polytetramethylene ether glycol.

  The content of the polyalkylene ether glycol is preferably 5 to 95% by mass, more preferably 10 to 85% by mass, and more preferably 20 to 80% by mass with respect to the block copolymer to be produced. Further preferred. If the content is in the above range, it is preferable because a polymer can be easily obtained by condensation polymerization. Further, the polyester copolymer in the present invention is (3) condensed with an aliphatic or alicyclic dicarboxylic acid and an aliphatic diol in place of the polyalkylene ether glycol having a weight average molecular weight of 400 to 6,000. Polyester oligomer synthesized from (5) aliphatic lactone or aliphatic monool carboxylic acid.

  Examples of (4) include 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, alicyclic dicarboxylic acids such as dicyclohexyl-4,4′-dicarboxylic acid or succinic acid, oxalic acid, adipic acid, And polyester oligomers having a structure in which one or more aliphatic dicarboxylic acids such as sebacic acid are condensed with one or more diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol. (5) Examples thereof include polycaprolactone-based polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid, and the like.

(Component A-5) Amide-type thermoplastic elastomer Examples of the amide-type thermoplastic elastomer include multi-block copolymers using polyamide as a hard segment and polyester diol or polyether diol having a low glass transition temperature as a soft segment.
Here, examples of the polyamide component include nylon-6, -66, -610, -11, and -12. Among them, nylon-6 and nylon-12 are preferable.
Examples of the polyether diol include poly (oxytetramethylene) glycol and poly (oxypropylene) glycol.
Examples of the polyester diol include poly (ethylene-1,4-adipate) glycol, poly (butylene-1,4-adipate) glycol, and polytetramethylene glycol. Specific examples of the polyamide-based elastomer include nylon 12 / polytetramethylene glycol block copolymer.

(Component A-6) Ethylene- (meth) acrylic ester thermoplastic elastomer The ethylene- (meth) acrylic ester thermoplastic elastomer is composed of a polymer block (hard segment) mainly composed of ethylene and (meth) acrylic. A block copolymer with a polymer block (soft segment) derived from an acid ester can be exemplified.
(Meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acrylic N-hexyl acid, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic Examples include isodecyl acid. These structural units may be contained independently and at least 2 types may be contained.
In addition to the structural units derived from ethylene and (meth) acrylic acid esters, terpolymers containing structural units derived from carbon monoxide are also preferred as the ethylene- (meth) acrylic acid ester-based thermoplastic elastomer.
Specific examples of the ethylene- (meth) acrylate ester-based thermoplastic elastomer include ethylene / n-butyl acrylate / carbon monoxide copolymer, ethylene / decyl acrylate / carbon monoxide copolymer, and the like. An ethylene / n-butyl acrylate / carbon monoxide copolymer is preferred.

  In the present invention, component A may be used alone or in combination of two or more. The content of Component A is preferably 10 to 95% by mass and more preferably 50 to 90% by mass in the total solid content from the balance between the form retention of the coating film and the engraving sensitivity. The “solid content” means a component excluding volatile components such as a solvent in the resin composition for laser engraving.

  Further, for the purpose of improving the laser engraving sensitivity of the relief forming layer, those obtained by introducing an easily decomposable functional group such as a carbamoyl group or a carbonate group into the main chain of these thermoplastic elastomers can also be used.

  Moreover, the product marketed can also be used as a component A, Kraton D1102JSZ (made by Kraton Polymers), Kraton D1161JSP (made by Kraton Polymers), Kraton G1650MU (made by Kraton Polymers), Kraton Polymers 17 ), Thermoran 3555N (Mitsubishi Chemical Corporation), Thermoran 5800B (Mitsubishi Chemical Corporation), Miractolan E190PNAT (Nihon Miraclan Corporation), Miractolan E390PNAT (Nihon Miractoran Corporation), Primalloy A1600N (Mitsubishi Chemical Corporation), UBESTA XPA 9055F1 (Ube Industries, Ltd.), Elvaloy HP441 (DuPont) Manufactured).

The weight average molecular weight of the thermoplastic elastomer is preferably 5,000 to 500,000, preferably 10,000 to 10,000, from the viewpoint of shape retention and solubility in a solvent when preparing the relief forming layer.
400,000 is more preferred, and 15,000 to 300,000 is even more preferred.
In addition, the weight average molecular weight (Mw) of resin etc. in this invention can be calculated | required by measuring using gel permeation chromatography (GPC), for example, and measuring and converting with a polystyrene with known molecular weight.
Specifically, for example, GPC uses HLC-8220GPC (manufactured by Tosoh Corporation), and TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgeL SuperHZ2000 (4.6 mm ID × 15 cm, manufactured by Tosoh Corporation) are used as columns. Three are used and THF (tetrahydrofuran) is used as an eluent. As conditions, the sample concentration is 0.35% by mass, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used. In addition, the calibration curve is “standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, It is prepared from 8 samples of “A-2500”, “A-1000”, “n-propylbenzene”.

(Component B) Polymerizable Compound From the viewpoint of forming a crosslinked structure in the relief forming layer, the resin composition for laser engraving used in the present invention contains (Component B) a polymerizable compound.
The polymerizable compound can be arbitrarily selected from compounds having at least one ethylenically unsaturated group, preferably 2 or more, more preferably 2 to 6, and still more preferably 2. Examples of the polymerizable compound include the polymerizable compounds described in paragraphs 0098 to 0124 of JP2009-255510A and JP2009-204962A.

Hereinafter, a monofunctional monomer having one ethylenically unsaturated group in the molecule and a polyfunctional monomer having two or more ethylenically unsaturated groups in the molecule will be described.
In the relief forming layer in the present invention, a polyfunctional monomer is preferably used since it is necessary to form a crosslinked structure. The molecular weight of these polyfunctional monomers is preferably 120 to 3,000, and more preferably 200 to 2,000.
Examples of monofunctional monomers and polyfunctional monomers include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.) and esters of polyhydric alcohol compounds, unsaturated carboxylic acids, Examples include amides with polyvalent amine compounds.
In the present invention, a di (meth) acrylate having an alkylene group having 1 to 20 carbon atoms is preferable, and a di (meth) acrylate having a linear or branched alkylene group having 2 to 10 carbon atoms is more preferable. Di (meth) acrylate having an alkylene group having 3 to 6 carbon atoms is more preferable. The alkylene group may have a substituent, and examples of the substituent include a hydroxy group.

By using a polymerizable compound in the resin composition of the present invention, film physical properties such as brittleness and flexibility in the relief forming layer can be adjusted.
In addition, the content of the polymerizable compound in the resin composition for laser engraving in the present invention is preferably 5 to 60% by mass, 8 to 30% by mass in terms of solid content, from the viewpoint of flexibility and brittleness of the crosslinked film. The range of is more preferable.

(Component C) Polymerization initiator The resin composition for laser engraving used in the present invention further contains (Component C) a polymerization initiator.
Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator, and a thermal polymerization initiator is preferable from the viewpoint of preferable crosslinking by heat. As the polymerization initiator, those known to those skilled in the art can be used without limitation.
Component C is preferably a radical polymerization initiator that promotes the addition polymerization of component B, and preferred examples thereof include compounds described in paragraphs 0074 to 0118 of JP-A-2008-63554.
As radical polymerization initiators, aromatic ketones, onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, carbon halogens Examples thereof include a compound having a bond and an azo compound. Among these, organic peroxides or azo compounds are more preferable, and organic peroxides are particularly preferable from the viewpoint of engraving sensitivity and a favorable relief edge shape when applied to the relief forming layer of the relief printing plate precursor.
As the organic peroxide, those described in JP-A-2008-63554 and JP-A-2008-233244 are preferable, and dicumyl peroxide and t-butylperoxybenzoate are more preferable.

Moreover, since the engraving sensitivity becomes high by using together the photothermal conversion agent mentioned later as a combined component of an organic peroxide, it is preferable. This is because when an organic peroxide is used to cure the relief forming layer by thermal crosslinking, unreacted organic peroxide that does not participate in radical generation remains, but the remaining organic peroxide is exothermic during laser engraving. Disassembled into As a result, the amount of heat generated is added to the irradiated laser energy, so that the engraving sensitivity is estimated to increase.
This effect is remarkable when carbon black is used as the photothermal conversion agent. This is because the heat generated from carbon black is also transferred to the organic peroxide. As a result, not only carbon black but also organic peroxide generates heat, and the generation of thermal energy to be used for decomposition of component A and the like is generated. This is because it is generated synergistically.

  A polymerization initiator may be used individually by 1 type, and can also use 2 or more types together. The content of the polymerization initiator in the resin composition in the present invention is preferably 0.01 to 10% by mass, and preferably 0.1 to 3% by mass with respect to the total mass of the solid content of the resin composition, from the viewpoint of printing durability. Is more preferable.

(Component D) Photothermal Conversion Agent The resin composition for laser engraving used in the present invention preferably further contains a photothermal conversion agent. It is considered that the photothermal conversion agent promotes thermal decomposition of the cured product during laser engraving by absorbing laser light and generating heat. For this reason, it is preferable to select a photothermal conversion agent that absorbs light having a laser wavelength used for engraving.
A flexographic printing plate precursor for laser engraving manufactured using the resin composition for laser engraving in the present invention is a light source that emits an infrared ray of 700 to 1,300 nm (YAG laser, semiconductor laser, fiber laser, surface emitting laser, etc.) As a photothermal conversion agent, it is preferable to use a compound having a maximum absorption wavelength at 700 to 1,300 nm. Various dyes or pigments are used as the photothermal conversion agent.

  Among the photothermal conversion agents, as the dye, commercially available dyes and known ones described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include those having a maximum absorption wavelength at 700 to 1,300 nm, such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, diimmonium compounds, and quinoneimine dyes. Preferred are dyes such as methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes. Dyes preferably used in the present invention include cyanine dyes such as heptamethine cyanine dyes, oxonol dyes such as pentamethine oxonol dyes, phthalocyanine dyes, and paragraphs 0124 to 0137 of JP-A-2008-63554. Mention may be made of dyes.

Among the photothermal conversion agents used in the present invention, commercially available pigments and color index (CI) manuals, “latest pigment manuals” (edited by the Japan Pigment Technical Association, published in 1977), “latest pigment application” The pigments described in “Technology” (CMC Publishing, 1986) and “Printing Ink Technology” CMC Publishing, 1984) can be used. Examples of the pigment include pigments described in paragraphs 0122 to 0125 of JP-A-2009-178869.
Of these pigments, carbon black is preferred. As long as the dispersibility in the composition is stable, any carbon black can be used regardless of the application, in addition to the classification based on ASTM. Carbon black includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black and the like. In order to facilitate dispersion, black colorants such as carbon black can be used as color chips or color pastes previously dispersed in nitrocellulose or a binder, if necessary. Such chips and pastes can be easily obtained as commercial products. Examples of carbon black include those described in paragraphs 0130 to 0134 of JP2009-178869A.

  The content of the photothermal conversion agent in the resin composition for laser engraving varies greatly depending on the molecular extinction coefficient inherent to the molecule, but is in the range of 0.01 to 30% by mass of the total solid content of the resin composition. Is preferable, 0.05-20 mass% is more preferable, and 0.1-10 mass% is especially preferable.

<Other ingredients>
In addition to Component A to Component D, the resin composition in the present invention can be used in combination with various compounds depending on the purpose as long as the effects of the present invention are not impaired. In the resin composition for laser engraving in the present invention, a known binder polymer not included in Component A can be used in combination with Component A. For example, from the viewpoint of laser engraving sensitivity, a polymer containing a partial structure that is thermally decomposed by exposure or heating is preferable. In addition, for example, when a soft and flexible film formation is intended, a soft resin is selected. Furthermore, it is preferable to use a hydrophilic or alcoholic polymer from the viewpoint of easy preparation of the composition for a relief forming layer and improvement in resistance to oil-based ink in the obtained relief printing plate. These components are described in JP2008-163081A.
Thus, in consideration of the physical properties according to the application application of the relief printing plate, a binder polymer can be selected according to the purpose, and one or more of the above binder polymers can be used in combination.

The solvent that can be used in preparing the resin composition for laser engraving in the present invention may be any solvent that can dissolve and disperse the constituents of the resin composition for laser engraving.
For example, acetonitrile, tetrahydrofuran, dioxane, toluene, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl acetate, butyl acetate, ethyl lactate, N, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, methanol, Examples include ethanol, 1-propanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, ethylene glycol, diethylene glycol, 1,3-propanediol, diethyl ketone, and cyclohexanone.

  Furthermore, the resin composition for laser engraving in the present invention can be appropriately blended with various additives usually used in the field of rubber as long as the effects of the present invention are not impaired. Examples include vulcanizing agents, fillers, plasticizers, waxes, process oils, organic acids, metal oxides, antiozonants, antiaging agents, thermal polymerization inhibitors, colorants, etc. You may use individually and may use 2 or more types together.

When process oil is used, for example, aromatic process oil, naphthenic process oil, and paraffinic process oil can be mentioned. The amount added is preferably 1 to 70 parts by mass per 100 parts by mass of component A.
The organic acid can be used as an auxiliary agent for vulcanization acceleration in combination with a conventional vulcanizing agent as a metal salt. Examples of the organic acid include stearic acid, oleic acid, and murastic acid. Examples of the metal source used in combination include metal oxides such as zinc oxide (zinc white) and magnesium oxide. In these vulcanization processes, organic acids and metal oxides form metal salts in the rubber, and the activation of vulcanizing agents such as sulfur is promoted. The amount of the metal oxide added to form such a metal salt in the system is preferably 0.1 to 10 parts by mass and more preferably 2 to 10 parts by mass per 100 parts by mass of Component A.
0.1-5 mass parts is preferable per 100 mass parts of component A, and, as for the addition amount of an organic acid, 0.1-3 mass parts is more preferable.

(Laser engraving type flexographic printing plate making kit)
The laser engraving-type flexographic printing plate making kit according to the present invention includes the flexographic printing plate precursor according to the present invention and the rinsing liquid of the present invention.
The preferred embodiments of the flexographic printing plate precursor in the present invention and the rinsing liquid of the present invention contained in the laser engraving type flexographic printing plate making kit in the present invention are the same as those described above.
Further, the flexographic printing plate making kit in the present invention may contain any product other than the printing plate precursor and the rinsing liquid.
For example, a rinsing brush, a non-woven fabric, a rinsing liquid spray container, and the like can be used, but the invention is not limited thereto.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the weight average molecular weight (Mw) of the polymer in an Example is displaying the value measured by GPC method unless there is particular notice. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

The compound names of Component A to Component D used in the flexographic printing plate precursors of Examples and Comparative Examples and Component 1 to Component 3 used in the rinse solutions of Examples and Comparative Examples are shown below.
<(Component A) Thermoplastic Elastomer>
A-1: Kraton D1102JSZ (styrene, SBS, manufactured by Kraton Polymers)
A-2: Kraton D1161 JSP (styrene, SIS, manufactured by Kraton Polymers)
A-3: Kraton G1650MU (styrene, SEBS, manufactured by Kraton Polymers)
A-4: Kraton G1730 (styrene-based, SEPS, manufactured by Kraton Polymers)
A-5: Thermolane 3555N (olefin-based, dynamic crosslinking, manufactured by Mitsubishi Chemical Corporation)
A-6: Thermoran 5800B (olefin-based, non-crosslinked, black, manufactured by Mitsubishi Chemical Corporation)
A-7: Milactolan E190PNAT (urethane, adipic acid polyester, manufactured by Nihon Milactolan Co., Ltd.)
A-8: Milactolan E390PNAT (urethane, polyether, manufactured by Nihon Milactolan)
A-9: Primalloy A1600N (ester, polyether, manufactured by Mitsubishi Chemical Corporation)
A-10: UBESTA XPA 9055F1 (amide type, manufactured by Ube Industries, Ltd.)
A-11: Elvaloy HP441 (ethylene- (meth) acrylic ester, ethylene / n-butyl acrylate / carbon monoxide copolymer, manufactured by DuPont)

<Binder polymer other than Component A>
A'-1: Nipol 1502 (styrene butadiene rubber, manufactured by Nippon Zeon Co., Ltd.)

<(Component B) polymerizable compound>
B-1: 1,6-hexanediol diacrylate (NK ester A-HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.)

<(Component C) Polymerization initiator>
C-1: Dicumyl peroxide (Park Mill D, manufactured by NOF Corporation)
C-2: Irgacure 651 (BASF)

<(Component D) Photothermal Conversion Agent>
D-1: Carbon black (MA100, manufactured by Mitsubishi Chemical Corporation)

<(Component 1) Organic solvent with specific structure>
1-1: 3-Pentanol (5.2 g / 100 ml)
1-2: 3-methyl-2-butanol (5.2 g / 100 ml)
1-3: Ethylene glycol mono t-butyl ether (mixed in water)
1-4: Propylene glycol mono-n-butyl ether (4.4 g / 100 ml)
1-5: Diethyl ketone (1.7 g / 100 ml)

<Organic solvents other than component 1>
1'-1: Isopropyl alcohol (mixed in water)
1′-2: n-butanol (6.4 g / 100 ml)
1′-3: benzyl alcohol (4.0 g / 100 ml)
1′-4: Ethylene glycol mono n-butyl ether (mixed in water)
1′-5: Ethylene glycol mono n-hexyl ether (1.0 g / 100 ml)
1'-6: Propylene glycol monomethyl ether (mixed in water)
1′-7: Diethylene glycol mono n-butyl ether (mixed in water)
1′-8: Diethylene glycol mono-2-ethylhexyl ether (0.3 g / 100 ml)
1′-9: 2-butanone (22 g / 100 ml)
1′-10: 4-methyl-2-pentanone (1.9 g / 100 ml)
1′-11: n-heptane (0.01 g / 100 ml)

<(Component 2) Amphoteric, Anionic Surfactant>
As component 2, the following compounds were used from among the compounds exemplified in paragraphs 0051 to 0067.
BO-5: Softazolin LAO (manufactured by Kawaken Fine Chemical Co., Ltd.)
BC-2: Takesurf C-157 (Takemoto Yushi Co., Ltd.)
BC-5: Levon 2000L (manufactured by Sanyo Chemical Industries)
BS-5: Softazolin LSB-R (manufactured by Kawaken Fine Chemical Co., Ltd.)
AP-3: Neoperex G-65 (manufactured by Kao Corporation)
AP-7: Eleminor MON-7 (manufactured by Sanyo Chemical Industries)
AN-2: Perex NBL (manufactured by Kao Corporation)
AN-6: New Call B-13SN (Takemoto Yushi Co., Ltd.)

<Surfactants other than Component 2>
W-1: Emalex 710 (ethylene oxide alkyl ether, nonionic surfactant, manufactured by Nippon Emulsifier Co., Ltd.)
W-2: New Coal B-13 (ethylene oxide naphthalene ether, nonionic surfactant, Takemoto Yushi Co., Ltd.)
W-3: Pionein B111 (lauryltrimethylammonium chloride, cationic surfactant, manufactured by Takemoto Yushi Co., Ltd.)

Example 1
<1. Preparation of flexographic printing plate precursor for laser engraving>
In a kneader manufactured by Moriyama Co., Ltd., (Component A) 84 parts of A-1 as a thermoplastic elastomer, (Component B) 9 parts of B-1 as a polymerizable compound, (Component D) D- 4 parts of 1 was added and kneaded at 200 ° C. for 180 minutes. Thereafter, after cooling to 160 ° C., 3 parts of C-1 as (Component C) polymerization initiator was added and kneaded for 5 minutes to obtain a resin composition 1 for laser engraving. Immediately thereafter, it was extruded to a thickness of 0.9 mm with an extruder manufactured by Moriyama Co., Ltd. and heated in an oven at 120 ° C. for 3 hours to obtain a relief forming layer 1.
A 15 μm-thick polypropylene (PP) film is attached as a cover film to one side of the relief forming layer, and a PET film having a thickness of 0.19 mm is applied to the opposite side of the relief forming layer using a UV curable adhesive. Laminated. At this time, the clearance of the laminate was adjusted so that the thickness of the UV curable adhesive was 0.05 mm, and the flexographic printing plate precursor 1 for laser engraving having a plate material thickness other than the cover film of 1.14 mm was produced. The Shore A hardness of the relief forming layer was measured by the above-described measuring method and found to be 82 °.

<2. Flexographic printing plate making>
The relief forming layer of the obtained master 1 was engraved with the following laser.
(Sculpture by FC-LD)
As a semiconductor laser engraving machine, a laser recording apparatus equipped with a fiber-coupled semiconductor laser (FC-LD) SDL-6390 (JDSU, wavelength 915 nm) having a maximum output of 8.0 W was used. A 30 μm convex fine wire was engraved with a semiconductor laser engraving machine under the conditions of laser output: 7.5 W, head speed: 409 mm / second, pitch setting: 2,540 DPI. When engraving with a semiconductor laser, the original data could be reproduced on the plate almost faithfully, and the convex fine line formed on the relief layer was 30 μm wide.

<3. Preparation of rinse solution>
The rinse solution of the present invention was prepared according to the following formulation.
(Component 1) 1-1 0.7 parts by mass (Component 2) BC-5 As solids, 5 parts by mass silicone-based antifoaming agent: TSA739 (manufactured by Toray Dow Corning Co., Ltd.) 0.01 parts by mass preservative : Biohope (isothiazoline / nitrobromoalcohol, manufactured by Riken Green Co., Ltd.) 0.01 parts by mass (component 3) tap water Adjusted so that the total amount of the liquid containing the above components is 100 parts by mass

<4. Rinse process>
The performance of the flexographic printing plate was evaluated with the following items, and the results are shown in Table 1.
The rinsing liquid is dropped onto the relief layer engraved by the above method with a dropper (about 100 ml / m ² ) so that the plate surface is evenly wet, and after standing for 2 minutes, a load of 200 gf (1 96 N), the plate was rubbed 20 times (30 seconds) in the vertical direction, and then the plate was rubbed 20 times (30 seconds) in the horizontal direction. Both the room temperature during rinsing and the temperature of the rinsing liquid were 25 ° C.
Thereafter, the plate surface was washed with running water, the water on the plate surface was removed, and air-dried for about 1 hour.

<5. Evaluation of flexographic printing plates>
[Rinse]
The surface of the rinsed flexographic printing plate was observed with a microscope (manufactured by Keyence Co., Ltd.) with a magnification of 100 times, and the remaining residue on the plate was evaluated. The evaluation criteria are as follows.
1: Waste is attached to the entire surface of the plate.
2: Slight residue remains on the convex portion of the plate image, and residue remains on the bottom (recess portion) of the image.
3: A slight amount of residue remains on the convex portion of the plate image, and a small amount of residue remains on the bottom (recess portion) of the image.
4: Only a slight residue remains on the bottom (recess) of the image.
5: No residue remains on the plate.
If the evaluation is 4 or more, it is a practically acceptable level.
In the table, the “rinsing ability” in the rinsing property item cannot be used as a rinsing solution because the organic solvent and water in the rinsing solution are separated into two phases, and the rinsing property cannot be evaluated. It means that.

[UV ink printing durability]
The obtained flexographic printing plate is set on a printing press (manufactured by Taiyo Machinery Co., Ltd.) using Lohmann 5.1+ as a cushion tape, and UV flexo 500 indigo (UV ink, manufactured by T & K TOKA) is used as ink. Using a 900 lpi anilox roller, printing was performed on full-color form M70 (manufactured by Nippon Paper Industries Co., Ltd., thickness: 100 μm) as printing paper. Printing was performed up to 500,000 copies under the condition that the touch pressure between the flexographic printing plate and the anilox roller was 100 μm indentation from the kiss touch, and the touch pressure between the flexographic printing plate and the printing paper was indented 160 μm from the kiss touch.
The thin line image of the obtained printed matter was observed with a magnifying glass, and when the fine line was interrupted or twisted, the printing was completed, and the number of copies that could be printed before the printing was used as an index of printing durability. The larger the value, the better the printing durability.
In the table, “not evaluated” in the UV ink printing durability item indicates that the rinsing property is at a very low level, so that the fine line image of the printed material has become a thick line of 60 μm width or more, or the rinsing property is “Evaluation not possible” means that the rinsing process could not be performed, and thus the UV ink printing durability could not be evaluated.

(Examples 2-120, Comparative Examples 1-26)
The component A, component 1 and component 2 compound types used in Example 1, and the prescription amounts of component 1 and component 2 and the laser species used for engraving were changed as shown in Tables 1 to 5 or 7, and Prepared a flexographic printing plate precursor for laser engraving and a rinsing solution in the same manner as in Example 1 except that an appropriate amount of sodium hydroxide was added to the rinsing solution so that the pH of the rinsing solution was the value shown in Table 1. Evaluation was conducted in the same manner as in Example 1.

(Engraving with CO ₂ laser)
In Examples 99 to 120, engraving with a carbon dioxide laser was performed.
As a carbon dioxide laser (CO ₂ laser) engraving machine, a high quality CO ₂ laser marker ML-9100 series (manufactured by Keyence Corporation) was used. After peeling the cover film from the printing plate precursor 1 for laser engraving, a carbon dioxide laser engraving machine was used to engrave a 30 μm wide convex fine line under the conditions of output: 12 W, head speed: 200 mm / second, pitch setting: 2,540 DPI . When engraving with a carbon dioxide laser, the image reproducibility on the plate with respect to the original data was inferior to that when using a semiconductor laser, and the convex fine lines formed in the relief layer had an average width of 24 μm.

(Examples 121-142)
Table 5 shows the component A, component 1 and component 2 compound types used in Example 1, and component 1 and component 2 prescription amounts without using the (component D) photothermal conversion agent described in Example 1. In addition, except that the laser used for engraving was changed to CO ₂ laser, a flexographic printing plate precursor for laser engraving and a rinsing solution were prepared in the same manner as in Example 1, except that the laser used for engraving was changed to CO ₂ laser. evaluated. The image reproducibility on the plate with respect to the original data at this time was slightly inferior to that when a semiconductor laser was used, and the convex fine lines formed on the relief layer had an average width of 27 μm.

(Examples 143 to 164)
Irgacure 651 (2,2-dimethoxy-1,2-diphenylethane-1-one as a photopolymerization initiator, manufactured by BASF, without using the (component D) photothermal conversion agent described in Example 1, ) And the molded relief forming layer is subjected to photochemical reinforcement and detacking as a crosslinking process (using a long wave UV light (UVA) to irradiate about 12 J / cm ² , followed by a short wave UV light ( UVC) irradiation) was added, and the compound A, component 1, and component 2 types used in Example 1 and the prescription amounts of component 1 and component 2 were changed as shown in Table 6, and further to engraving A flexographic printing plate precursor and a rinsing liquid for laser engraving were prepared and evaluated in the same manner as in Example 1 except that the laser used was a CO ₂ laser. At this time, the image reproducibility on the plate with respect to the original data was slightly inferior to that when a semiconductor laser was used, and the convex fine lines formed in the relief layer had an average width of 36 μm.

(Comparative Example 27)
The rinsing solution described in Example 1 was used as a Purple Power Industrial Strength Cleaner / Degreaser
A flexographic printing plate precursor for laser engraving was prepared in the same manner as in Example 1 except that it was changed to (manufactured by AIKEN Chemical, pH 11.2, containing ethylene glycol mono n-butyl ether, undiluted and used in the stock solution). Evaluation was performed in the same manner as in Example 1.

Claims (13)

Preparing a flexographic printing plate precursor for laser engraving having a crosslinked relief-forming layer;
A step of laser engraving the printing plate precursor into an image,
The engraved surface (component 1) alcohols represented by the following formula (I), ethylene glycol ethers represented by the following formula (II), and ketones represented by the following formula (III), Rinsing with an aqueous rinsing liquid containing an organic solvent selected from the group consisting of: (Component 2) an amphoteric surfactant and / or an anionic surfactant; and (Component 3) water. Contains,
The crosslinked relief-forming layer comprises a resin composition for laser engraving containing (Component A) a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator. A layer crosslinked by light,
The content of component 1 is 0.5 to 45% by mass with respect to the total mass of the aqueous rinse liquid,
How to make flexographic printing plates.

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4-5,
In formula (II), X and Y each independently represent a hydrogen atom or a methyl group. When X and Y are both hydrogen atoms, R ⁴ represents an n-propyl group, an isopropyl group, or a branched butyl group. , R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and when one of X and Y is a hydrogen atom and the other is a methyl group, R ⁴ has 3 to ⁴ carbon atoms. Represents a linear or branched alkyl group, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms,
In formula (III), R ⁶ and R ⁷ each independently represent an alkyl group having 1 to 3 carbon atoms, and the total number of carbon atoms of R ⁶ and R ⁷ is 4 to 6. ]   Component 1 is 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 4-methyl-2-pentanol The method for making a flexographic printing plate according to claim 1, which is a compound selected from the group consisting of ethylene glycol mono-t-butyl ether, propylene glycol mono-n-butyl ether, diethyl ketone, and 2-pentanone.   The plate making method of a flexographic printing plate according to claim 2, wherein component 1 is propylene glycol mono n-butyl ether or diethyl ketone.   The plate making method of a flexographic printing plate according to any one of claims 1 to 3, wherein the solubility of component 1 in water at 20 ° C is 1.5 to 10.0 g / 100 ml. The plate making method of the flexographic printing plate as described in any one of Claims 1-4 whose component 2 is an amphoteric surfactant represented by following formula (IV) or following formula (V).

Wherein (IV), R ⁸ ~R ¹⁰ independently denotes a monovalent organic group,
In the formula (V), R ^{11 to} R ¹³ each independently represents a monovalent organic group, L represents a divalent linking group, and A represents COO or SO ₃ . ]   The plate making method of the flexographic printing plate as described in any one of Claims 1-4 whose component 2 is a benzenesulfonate, naphthalenesulfonate, or a sulfate ester salt.   The plate making method of the flexographic printing plate as described in any one of Claims 1-6 whose component A is a styrene-type thermoplastic elastomer.   The flexographic printing plate obtained by the plate-making method of the flexographic printing plate as described in any one of Claims 1-7. (Component 1) selected from the group consisting of alcohols represented by the following formula (I), ethylene glycol ethers represented by the following formula (II), and ketones represented by the following formula (III) An organic solvent, (Component 2) an amphoteric surfactant, and / or an anionic surfactant, and (Component 3) water,
The content of component 1 is 0.5 to 45% by mass with respect to the total mass of the aqueous rinse liquid,
Rinsing solution for laser engraving flexographic printing plates.

[Expressed in formula ^{(I), R 1, R} 2 and R ³ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group of 3-4 carbon atoms, R ^1, The total number of carbon atoms of R ² and R ³ is 4-5,
In formula (II), X and Y each independently represent a hydrogen atom or a methyl group. When X and Y are both hydrogen atoms, R ⁴ represents an n-propyl group, an isopropyl group, or a branched butyl group. , R ⁵ represents a hydrogen atom, an n-propyl group, an isopropyl group, or a branched butyl group, and when one of X and Y is a hydrogen atom and the other is a methyl group, R ⁴ has 3 to ⁴ carbon atoms. Represents a linear or branched alkyl group, R ⁵ represents a hydrogen atom or a linear or branched alkyl group having 3 to 4 carbon atoms,
In formula (III), R ⁶ and R ⁷ each independently represent an alkyl group having 1 to 3 carbon atoms, and the total number of carbon atoms of R ⁶ and R ⁷ is 4 to 6. ]   Component 1 is 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 4-methyl-2-pentanol The rinse solution for laser engraving-type flexographic printing plates according to claim 9, which is a compound selected from the group consisting of ethylene glycol mono t-butyl ether, propylene glycol mono n-butyl ether, diethyl ketone, and 2-pentanone.   The rinse liquid for laser engraving-type flexographic printing plates according to claim 10, wherein Component 1 is propylene glycol mono n-butyl ether or diethyl ketone.   The rinse liquid for laser engraving-type flexographic printing plates according to any one of claims 9 to 11, wherein the solubility of component 1 in water at 20 ° C is 1.5 to 10.0 g / 100 ml. A relief forming layer obtained by crosslinking a resin composition for laser engraving containing (Component A) a thermoplastic elastomer, (Component B) a polymerizable compound, and (Component C) a polymerization initiator by heat and / or light. A flexographic printing plate precursor for laser engraving, and
It contains the rinse liquid for laser engraving-type flexographic printing plates according to any one of claims 9 to 12,
Laser engraving flexographic printing plate making kit.