JP2012158048A - Method for making relief printing plate and relief printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for making a relief printing plate, which has superior productivity, and by which a high quality image can be formed.SOLUTION: The method for making the relief printing plate includes: a step of preparing an original plate for a relief printing plate including a crosslinked relief formation layer; and an engraving step of performing laser engraving to the original plate for the relief printing plate: wherein the crosslinked relief formation layer is formed by crosslinking a relief formation layer containing (component A) a binder polymer and (component B) a photothermal conversion agent, the content of component B is ≥0.1 wt.%, the engraving step is the step to perform using an exposure head with at least two juxtaposed semiconductor lasers having a wavelength of 700-1,300 nm, and in the engraving step, gas is blown to a laser irradiation part at a wind speed of 10 m/s or more, and the blowing angle of the gas is ≥0° and <90°.

Description

  The present invention relates to a method for making a relief printing plate and a relief printing plate.

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 original plate is directly irradiated with a laser, and thermal decomposition and volatilization are caused by photothermal conversion to form a recess. Unlike the relief formation using the original film, the direct engraving CTP method can freely control the relief shape. For this reason, when an image such as a letter is formed, the area is engraved deeper than other areas, or the fine halftone dot image is engraved with a shoulder in consideration of resistance to printing pressure. Is also possible. In general, a high-power carbon dioxide laser is used as a laser for this method. In the case of a carbon dioxide laser, all organic compounds can absorb irradiation energy and convert it into heat. On the other hand, inexpensive and small-sized semiconductor lasers have been developed. However, since these are visible and near infrared light, it is necessary to absorb the laser light and convert it into heat.
For example, Patent Document 1 is known as a conventional resin composition for laser engraving.

International Publication No. 2010/090345

  An object of the present invention is to provide a plate making method of a relief printing plate which is excellent in productivity and can form a high quality image. Furthermore, another object of the present invention is to provide a relief printing plate obtained by the plate making method.

The above-mentioned problems of the present invention have been solved by means described in the following <1> and <6>. It is described below together with <2> to <5> which are preferred embodiments.
<1> including a step of preparing a relief printing plate precursor having a crosslinked relief forming layer, and an engraving step of laser engraving the relief printing plate precursor, wherein the crosslinked relief forming layer comprises (Component A) a binder polymer, and (Component B) A relief forming layer containing a photothermal conversion agent is crosslinked, and the content of Component B is 0.1% by weight or more based on the total solid content of the relief forming layer, and the engraving step Is a step of engraving using an exposure head in which at least two semiconductor lasers having wavelengths of 700 nm to 1,300 nm are arranged, and in the engraving step, gas is blown at a wind speed of 10 m / s or more with respect to the laser irradiation portion. The spraying angle of the gas is 0 ° or more and less than 90 ° when the angle parallel to the printing plate and the angle opposite to the drawing direction is 0 °. A method for making a relief printing plate,
<2> The plate making method of the relief printing plate according to <1>, wherein the crosslink relief forming layer has a crosslink density of 10 × 10 ² mol / mL or more,
<3> The component B is carbon black having an oil absorption of less than 150 mL / 100 g and / or a pigment and / or dye having peak light absorption at 800 nm to 1,200 nm, <1> or <2> Plate-making method of the relief printing plate as described,
<4> The plate making of a relief printing plate according to any one of <1> to <3>, wherein the component B is contained in an amount of 0.1% by weight to 15% by weight with respect to the total solid content of the relief forming layer. Method,
<5> The method for making a relief printing plate according to any one of <1> to <4>, wherein the semiconductor laser is a fiber-attached semiconductor laser,
<6> A relief printing plate obtained by the method according to any one of <1> to <5>.

  ADVANTAGE OF THE INVENTION According to this invention, it was excellent in productivity and the plate making method of the relief printing plate which can form a high quality image was able to be provided. Furthermore, according to the present invention, a relief printing plate obtained by the plate making method can be provided.

It is an example of the block diagram of the plate-making apparatus used suitably by this invention. It is an example of the block diagram of the optical fiber array part arrange | positioned in an exposure head. It is an example of the enlarged view of the light emission part of an optical fiber array part. It is an example of the schematic diagram of the missing optical system of an optical fiber array part. It is an example of the relationship figure of the arrangement row | line | column of an optical fiber in an optical fiber array part, and a scanning line. It is an example of the top view which shows the outline | summary of the scanning exposure system in a plate-making apparatus. It is an example of the schematic diagram which shows the structural example of the optical fiber array light source which concerns on other embodiment. It is an example of the principal part side surface schematic diagram of the plate-making apparatus used suitably by this invention.

The plate-making method of the relief printing plate of the present invention includes a step of preparing a relief printing plate precursor having a crosslinked relief forming layer, and an engraving step of laser engraving the relief printing plate precursor, wherein the crosslinked relief forming layer comprises: A relief forming layer containing component A) a binder polymer and (component B) a photothermal conversion agent is cross-linked, and the content of the component B is 0.1 weight with respect to the total solid content of the relief forming layer. The engraving step is a step of engraving using an exposure head in which at least two semiconductor lasers having wavelengths of 700 nm to 1,300 nm are arranged, and in the engraving step, 10 m is applied to the laser irradiation portion. The gas is blown at a wind speed of at least / s, and the gas blowing angle is 0 ° when the angle parallel to the printing plate and the direction opposite to the drawing direction is 0 °. The angle is less than 90 °.
In the present invention, the description of “lower limit to upper limit” representing a numerical range represents “lower limit or higher and lower limit or lower”, and the description of “upper limit to lower limit” represents “lower limit or higher and lower limit or higher”. That is, it represents a numerical range including an upper limit and a lower limit. In the present invention, “(component A) binder polymer” or the like is also simply referred to as “component A” or “binder polymer” or the like.

Further, in the present specification, regarding the description of the relief printing plate, the image forming layer used for laser engraving is a flat surface and an uncrosslinked crosslinkable layer is referred to as a relief forming layer, A layer obtained by crosslinking the layers is referred to as a crosslinked relief forming layer, and a layer in which irregularities are formed on the surface by laser engraving is referred to as a relief layer.
In the present invention, a relief forming layer formed from a resin composition for laser engraving containing component A and component B (hereinafter also simply referred to as “resin composition”) is thermally crosslinked to have a crosslinked relief forming layer. It is preferable to obtain a printing plate precursor.
Hereinafter, components of the relief forming layer of the relief printing plate precursor will be described.

(Component A) Binder Polymer In the present invention, the (Component A) binder polymer is preferably a water-insoluble binder polymer that is soluble in an alcohol having 1 to 4 carbon atoms.
Component A preferably has an ethylenically unsaturated bond, an epoxy group, an amino group, a (meth) acryloyl group, a mercapto group, or a hydroxyl group (—OH). Among these, a hydroxyl group (—OH) is preferably present. More preferably. Hereinafter, the binder polymer having any of the above groups is also referred to as (Component A-1) specific polymer.

[(Component A-1) Specific polymer]
As a specific polymer in the present invention, a polyvinyl butyral (PVB) derivative and an acrylic resin having a hydroxyl group in a side chain from the viewpoint of achieving both water-based ink suitability and UV ink suitability, and high engraving sensitivity and good film properties. An epoxy resin having a hydroxyl group in the side chain and the like are preferably exemplified.

  The specific polymer that can be used in the present invention has a glass transition temperature (Tg) of 20 ° C. or higher when combined with a (component B) photothermal conversion agent, which is a combined component constituting the relief forming layer in the present invention. This is particularly preferable because the engraving sensitivity is improved. Hereinafter, a polymer having such a glass transition temperature is referred to as a non-elastomer. That is, an elastomer is generally defined scientifically as a polymer having a glass transition temperature of room temperature or lower (see Science Dictionaries 2nd Edition, Editor International Science Promotion Foundation, published by Maruzen Co., Ltd., P154). ). Therefore, a non-elastomer refers to a polymer having a glass transition temperature exceeding normal temperature. Although there is no restriction | limiting in the upper limit of the glass transition temperature of a specific polymer, it is preferable from a viewpoint of handleability that it is 200 degrees C or less, and it is more preferable that it is 25 degreeC or more and 120 degrees C or less.

When a polymer having a glass transition temperature of room temperature (20 ° C.) or higher is used, the specific polymer takes a glass state at room temperature. For this reason, the thermal molecular motion is considerably suppressed as compared with the rubber state. In laser engraving, in addition to the heat imparted by the infrared laser during laser irradiation, the heat generated by the function of the (component B) photothermal conversion agent is transferred to the surrounding specific polymer, which decomposes and dissipates. As a result, engraving is performed to form a recess.
In the present invention, when a photothermal conversion agent is present in a state in which the thermal molecular motion of a specific polymer is suppressed, it is considered that heat transfer and thermal decomposition to the specific polymer occur effectively. It is estimated that the engraving sensitivity has further increased.

  Specific examples of the non-elastomer polymer which is a particularly preferable embodiment of the specific polymer preferably used in the present invention are given below.

(1) Polyvinyl acetal and derivatives thereof Polyvinyl acetal is a compound obtained by cyclic acetalization of polyvinyl alcohol (obtained by saponifying polyvinyl acetate). Further, the polyvinyl acetal derivative is obtained by modifying the polyvinyl acetal or adding another copolymer component.
The acetal content in the polyvinyl acetal (mole% of vinyl alcohol units to be acetalized with the total number of moles of the starting vinyl acetate monomer being 100%) is preferably 30% to 90%, more preferably 50% to 85%. 55% to 78% is particularly preferable.
The vinyl alcohol unit in the polyvinyl acetal is preferably 10 mol% to 70 mol%, more preferably 15 mol% to 50 mol%, more preferably 22 mol% to 45 mol, based on the total number of moles of the raw material vinyl acetate monomer. % Is particularly preferred.
Moreover, the polyvinyl acetal may have a vinyl acetate unit as another component, and the content thereof is preferably 0.01 to 20 mol%, more preferably 0.1 to 10 mol%. The polyvinyl acetal derivative may further have other copolymer units.
Examples of the polyvinyl acetal include polyvinyl butyral, polyvinyl propylal, polyvinyl ethylal, and polyvinyl methylal. Among them, polyvinyl butyral (hereinafter referred to as PVB) is preferable.
Polyvinyl butyral is usually a polymer obtained by converting polyvinyl alcohol into butyral. A polyvinyl butyral derivative may also be used.
Examples of polyvinyl butyral derivatives include acid-modified PVB in which at least part of the hydroxyl group is modified to an acid group such as a carboxyl group, modified PVB in which part of the hydroxyl group is modified to a (meth) acryloyl group, and at least part of the hydroxyl group is an amino group. Modified PVB, modified PVB in which ethylene glycol, propylene glycol, or a multimer thereof is introduced into at least a part of the hydroxyl group.
The molecular weight of the polyvinyl acetal is preferably 5,000 to 800,000, more preferably 8,000 to 500,000 as a weight average molecular weight from the viewpoint of maintaining a balance between engraving sensitivity and film property. Further, from the viewpoint of improving the rinse performance of engraving residue, it is particularly preferably 50,000 to 300,000.

Hereinafter, although polyvinyl butyral (PVB) and its derivative (s) are mentioned and demonstrated as a particularly preferable example of polyvinyl acetal, it is not limited to this.
As PVB, it can also be obtained as a commercial product, and preferred specific examples thereof include “ESREC B” series and “ESREC K” manufactured by Sekisui Chemical Co., Ltd. from the viewpoint of alcohol solubility (particularly ethanol solubility). (KS) "series," Denkabutyral "manufactured by Denki Kagaku Kogyo Co., Ltd. are preferred. More preferably, from the viewpoint of alcohol solubility (especially ethanol), “S Lec B” series manufactured by Sekisui Chemical Co., Ltd. and “Denka Butyral” manufactured by Denki Kagaku Kogyo Co., Ltd. are particularly preferable. In the series, “BL-1”, “BL-1H”, “BL-2”, “BL-5”, “BL-S”, “BX-L”, “BM-S”, “BH-S” In “Denka Butyral” manufactured by Denki Kagaku Kogyo Co., Ltd., “# 3000-1”, “# 3000-2”, “# 3000-4”, “# 4000-2”, “# 6000-C”, “ # 6000-EP ","# 6000-CS ", and"# 6000-AS ".
When a relief forming layer is formed using PVB as a specific polymer, a method in which a solution dissolved in a solvent is cast and dried is preferable from the viewpoint of the smoothness of the surface of the membrane.

(2) Acrylic resin The acrylic resin that can be used as the specific polymer in the present invention is an acrylic resin obtained by using a known acrylic monomer, and any acrylic resin having a hydroxyl group in the molecule can be used. .
As the acrylic monomer used for the synthesis of the acrylic resin having a hydroxyl group, for example, (meth) acrylic acid esters and crotonic acid esters (meth) acrylamides having a hydroxyl group in the molecule are preferable. Specific examples of such a monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like.

Moreover, as an acrylic resin, acrylic monomers other than the acrylic monomer which has the said hydroxyl group can also be included as a copolymerization component. Examples of such acrylic monomers include (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, acetoxyethyl (meth) acrylate, phenyl (meth) acrylate, 2-methoxy Ethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, diethylene glycol mono Tyl ether (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, diethylene glycol monophenyl ether (meth) acrylate, triethylene glycol monomethyl ether (meth) acrylate, triethylene glycol monoethyl ether (meth) acrylate, dipropylene glycol monomethyl ether (Meth) acrylate, polyethylene glycol monomethyl ether (meth) acrylate, polypropylene glycol monomethyl ether (meth) acrylate, monomethyl ether (meth) acrylate of a copolymer of ethylene glycol and propylene glycol, N, N-dimethylaminoethyl (meta ) Acrylate, N, N-diethylaminoethyl (meth) acrylate, N N- dimethylaminopropyl (meth) acrylate.
Furthermore, a modified acrylic resin comprising an acrylic monomer having a urethane bond or a urea bond can also be preferably used.
Among these, alkyl (meth) acrylates such as lauryl (meth) acrylate and (meth) acrylates having an aliphatic cyclic structure such as t-butylcyclohexyl methacrylate are particularly preferable from the viewpoint of water-based ink resistance.

Moreover, novolak resin which is resin which condensed phenols and aldehydes on acidic conditions can be used as a specific polymer.
Preferred novolak resins include, for example, novolak resins obtained from phenol and formaldehyde, novolak resins obtained from m-cresol and formaldehyde, novolak resins obtained from p-cresol and formaldehyde, novolak resins obtained from o-cresol and formaldehyde, and octylphenol. And novolak resins obtained from formaldehyde, m- / p-mixed cresol and novolak resins obtained from formaldehyde, phenol / cresol (m-, p-, o- or m- / p-, m- / o-, o- / P-mixed) and a novolak resin obtained from formaldehyde.
These novolak resins preferably have a weight average molecular weight of 800 to 200,000 and a number average molecular weight of 400 to 60,000.
It is also possible to use an epoxy resin having a hydroxyl group in the side chain as the specific polymer. As a preferable specific example, an epoxy resin obtained by polymerizing an adduct of bisphenol A and epichlorohydrin as a raw material monomer is preferable.
These epoxy resins preferably have a weight average molecular weight of 800 to 200,000 and a number average molecular weight of 400 to 60,000.

Among the specific polymers, polyvinyl butyral and derivatives thereof are particularly preferable from the viewpoint of rinsing properties and printing durability when used as a relief forming layer and a crosslinked relief forming layer.
The content of the hydroxyl group contained in the specific polymer in the present invention is preferably 0.1 to 15 mmol / g, more preferably 0.5 to 7 mmol / g in any of the above-described polymers. .
In the present invention, only one type of specific polymer may be used in the resin composition for laser engraving, or two or more types may be used in combination.
The weight average molecular weight of the specific polymer that can be used in the present invention (polystyrene conversion by GPC measurement) is preferably 5,000 to 1,000,000, and more preferably 8,000 to 750,000. More preferably, it is 10,000 to 500,000.
The preferable content of the specific polymer in the resin composition for laser engraving that can be used in the present invention is 2 to 95% by weight in the total solid content from the viewpoint of satisfying a good balance of form retention, water resistance and engraving sensitivity. More preferably, it is 5 to 80% by weight, particularly preferably 10 to 60% by weight.

[(Component A-2) Combined Polymer]
In the present invention, the resin composition for laser engraving includes (Component A) as a binder polymer, in addition to the above (Component A-1) specific polymer, a polymer having no hydroxyl group, etc. (Component A-1) as a specific polymer Not known polymers can be used in combination. Hereinafter, such a polymer is referred to as (Component A-2) combined use polymer.
The combined polymer constitutes the main component contained in the resin composition for laser engraving together with the specific polymer, and a general polymer compound not included in the specific polymer is appropriately selected, and one or two or more types are used. Can be used in combination. In particular, when used for a relief printing plate precursor, it is necessary to select in consideration of various performances such as laser engraving property, ink acceptability, and engraving residue dispersibility.

  As the polymer used, polystyrene resin, polyester resin, polyamide resin, polyurea polyamideimide resin, polyurethane resin, polysulfone resin, polyethersulfone resin, polyimide resin, polycarbonate resin, hydrophilic polymer containing hydroxyethylene unit, acrylic resin, polycarbonate resin , Rubber, thermoplastic elastomer and the like.

  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. Preferred examples of such a polymer include those described in JP 2008-163081 A [0038]. For example, when the purpose is to form a soft and flexible film, a soft resin or a thermoplastic elastomer is selected. JP-A-2008-163081 discloses details in [0039] to [0040]. 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. As the hydrophilic polymer, those described in detail in JP 2008-163081 A [0041] can be used.

  In addition, polyesters composed of hydroxycarboxylic acid units such as polylactic acid can be preferably used. Specific examples of such polyesters include polyhydroxyalkanoate (PHA), lactic acid-based polymer, polyglycolic acid (PGA), polycaprolactone (PCL), poly (butylene succinic acid), and derivatives or mixtures thereof. Those selected from the group consisting of are preferred.

In addition, when used for the purpose of curing by heating or exposure and improving the strength, a polymer having a carbon-carbon unsaturated bond in the molecule is preferably used.
Examples of such a polymer that includes a carbon-carbon unsaturated bond in the main chain include SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), and SEBS. (Polystyrene-polyethylene / polybutylene-polystyrene) and the like.

Examples of the polymer having a carbon-carbon unsaturated bond in the side chain include carbon-carbon unsaturated groups such as an allyl group, an acryloyl group, a methacryloyl group, a styryl group, and a vinyl ether group in the skeleton of the binder polymer applicable in the present invention. It is obtained by introducing a saturated bond into the side chain. In the method of introducing a carbon-carbon unsaturated bond into the side chain of the binder polymer, a structural unit having a polymerizable group precursor formed by bonding a protective group to a polymerizable group is copolymerized with the polymer, and the protective group is eliminated. To prepare a polymer compound having a plurality of reactive groups such as a hydroxyl group, an amino group, an epoxy group, and a carboxyl group, and to react with these reactive groups and a carbon-carbon unsaturated bond. A known method such as a method of introducing the compound having a polymer reaction by polymer reaction can be employed. According to these methods, the amount of unsaturated bonds and polymerizable groups introduced into the polymer compound can be controlled.
As described above, in consideration of the physical properties according to the application application of the relief printing plate, a combination polymer can be selected according to the purpose, and one type of the combination polymer or a combination of two or more types can be used.

  The weight average molecular weight (in terms of polystyrene by GPC measurement) of the combined polymer in the present invention is preferably from 50,000 to 500,000. If the weight average molecular weight is 50,000 or more, the form retainability as a single resin is excellent, and if it is 500,000 or less, it is easy to dissolve in a solvent such as water, which is convenient for preparing a relief forming layer. The weight average molecular weight of the combined use polymer is more preferably 10,000 to 400,000, and particularly preferably 15,000 to 300,000.

The total content of the binder polymer [the total content of the (component A-1) specific polymer and the (component A-2) combined polymer] is 5% by weight to the total solid content of the resin composition for laser engraving. 95 weight% is preferable, 15 weight%-80 weight% is more preferable, and 20 weight%-65 weight% is still more preferable.
For example, when the resin composition for laser engraving is applied to the relief forming layer of the relief printing plate precursor, the resulting relief printing plate can be used as a printing plate by setting the binder polymer content to 5% by weight or more. Insufficient printing durability is obtained, and by making it 95% by weight or less, other components are not deficient, and flexibility sufficient to be used as a printing plate even when a relief printing plate is used as a flexographic printing plate. Obtainable.

(Component B) Photothermal Conversion Agent In the present invention, the relief forming layer contains (Component B) a photothermal conversion agent. It is considered that the photothermal conversion agent promotes thermal decomposition of the cured product of the resin composition for laser engraving by absorbing laser light and generating heat. Therefore, it is preferable to select a photothermal conversion agent that absorbs light having a laser wavelength used for engraving.

In the present invention, a semiconductor laser emitting an infrared ray having a wavelength of 700 nm to 1,300 nm is used as a light source for laser engraving. Therefore, the relief forming layer in the present invention is a photothermal conversion agent capable of absorbing light having a wavelength of 700 nm to 1,300 nm. It is preferable to contain.
Various dyes or pigments are used as the photothermal conversion agent in the present invention.
The photothermal conversion agent may be one or more photothermal conversion agents selected from carbon black having an oil absorption of less than 150 mL / 100 g and / or pigments and / or dyes having absorption at 800 nm to 1,200 nm. More preferred.
The photothermal conversion agent is preferably a pigment.

  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 nm to 1,300 nm. Azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, diimmonium compounds, quinone imine dyes , Methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, and metal thiolate complexes. In particular, cyanine dyes such as heptamethine cyanine dye, oxonol dyes such as pentamethine oxonol dye, and phthalocyanine dyes are preferably used. Examples thereof include the dyes described in paragraphs [0124] to [0137] of JP-A-2008-63554.

  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 black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

Preferred examples of the photothermal conversion agent in the present invention include carbon black from the viewpoints of stability and photothermal conversion efficiency. Carbon black is usually used for various applications such as for color, rubber, and dry batteries, as long as there is no problem with dispersion stability in the composition constituting the relief forming layer, as well as products with standards classified by ASTM. Any carbon black can be used.
The carbon black here includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black, and the like. In addition, in order to facilitate dispersion, black colorants such as carbon black use a dispersant as needed, and as a color chip or color paste previously dispersed in nitrocellulose or a binder, the relief forming layer composition Such chips and pastes can be easily obtained as commercial products.
In the present invention, it is also possible to use carbon black having a relatively low specific surface area and relatively low DBP absorption and even finer carbon black having a large specific surface area.
Examples of suitable carbon black commercial products include Printex A (registered trademark) or Special schwarz 4 (registered trademark) (both manufactured by Degussa), Seast 600 ISAF-LS (manufactured by Tokai Carbon Co., Ltd.), Asahi # 70 (N-300) (Asahi Carbon Co., Ltd.), Show Black N110 (Cabot Japan Co., Ltd.) and the like.

In the present invention, carbon black having an oil absorption of less than 150 ml / 100 g is preferred from the viewpoint of dispersibility in the resin composition for laser engraving.
For such selection of carbon black, for example, “Carbon Black Handbook” edited by Carbon Black Association can be referred to.
It is preferable to use carbon black having an oil absorption of less than 150 ml / 100 g because good dispersibility can be obtained in the relief forming layer. On the other hand, when carbon black having an oil absorption of 150 ml / 100 g or more is used, dispersibility in the relief forming layer coating solution tends to deteriorate, and carbon black tends to agglomerate. Unevenness occurs, which is not preferable. In addition, in order to prevent aggregation, it is necessary to strengthen the dispersion of carbon black at the time of preparing a coating solution, which may cause a problem that the degree of freedom in formulation is reduced.
The oil absorption of carbon black is preferably 10 to 149 ml / 100 g, more preferably 20 to 135 ml / 100 g, and still more preferably 30 to 125 ml / 100 g.
The DBP oil absorption amount (DBP absorption amount) is measured according to JIS K6217-4.

  The carbon black described above may be acidic or basic carbon black. The carbon black is preferably basic carbon black. Of course, mixtures of carbon blacks having different properties can also be used.

  The content of the photothermal conversion agent in the relief forming layer varies greatly depending on the molecular extinction coefficient inherent to the molecule, but is 0.1% by weight or more of the total weight of the solid content. When the content is less than 0.1% by weight, the photothermal conversion efficiency is lowered and the productivity is lowered. The content of the photothermal conversion agent is preferably 0.1 to 15% by weight, more preferably 0.2 to 13% by weight, and still more preferably 0.3 to 12% by weight.

  In the present invention, the relief forming layer comprises (Component C) Compound (I), (Component D) polymerizable compound, (Component E) together with the above-described (Component A) binder polymer and (Component B) photothermal conversion agent. It preferably contains optional components such as an alcohol exchange reaction catalyst, (component F) polymerization initiator, and (component G) plasticizer. Hereinafter, each of these components will be described in detail.

(Component C) Compound (I)
In the present invention, the relief forming layer and the resin composition for laser engraving preferably contain a compound (compound (I)) capable of introducing a group represented by the following formula (I) into the polymer.
-M (R ¹ ) (R ² ) _n (I)
(In the formula (I), R ¹ represents OR ³ or a halogen atom, M represents Si, Ti, or Al. When M is Si, n is 2, and when M is Ti, n is 2. And when M is Al, n is 1, each of R ² independently represents a hydrocarbon group, OR ³ or a halogen atom, and R ³ represents a hydrogen atom or a hydrocarbon group.)
In addition, the compound (I) may be one in which a group represented by the above formula (I) is introduced into the polymer by reaction with a polymer, and has a group represented by the above formula (I) before the reaction, A group represented by the above formula (I) may be introduced into the polymer.

As the compound (I), an embodiment in which M is Si is particularly preferable.
When M is Si, it is also possible to use a silane coupling agent as the compound having the group represented by the formula (I) (compound (I)). The silane coupling agent is a compound having a group capable of reacting with an inorganic component such as an alkoxysilyl group and a group capable of reacting with an organic component such as a methacryloyl group, and capable of binding the inorganic component and the organic component. is there. The same applies to titanium coupling agents and aluminate coupling agents.
Compound (I) has a reactive group such as a vinyl group, an epoxy group, a methacryloyloxy group, an acryloyloxy group, a mercapto group, and an amino group, and reacts with the polymer with the reactive group, whereby the polymer has the formula (I It is also preferred that a group represented by

Examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ -Glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ- Methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimeth Sisilane, N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercapto Examples thereof include propyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane.
As the compound (I), a compound having a plurality of groups represented by the formula (I) is also preferably used. In such a case, the group represented by the formula (I) can be introduced into the polymer by reacting a part of the group represented by the formula (I) with the polymer. For example, the R ¹ group and optionally the R ² group of compound (I) react with an atom and / or group (eg, hydroxyl group (—OH)) that can react with the compound in the polymer (eg, alcohol exchange). react. In addition, when a plurality of groups represented by the formula (I) are bonded to the polymer, the compound (I) also functions as a crosslinking agent, and can form a crosslinked structure.
Such a compound (I) is a compound having a plurality of groups represented by the formula (I), preferably a compound having 2 to 6 formula (I) structures, particularly 2 to 3 compounds. A compound having the structure of formula (I) is preferred.
Although the compound shown with the following general formula is mentioned as a preferable thing, this invention is not restrict | limited to these compounds.

In the above formulas, R represents a partial structure selected from the following structures. When a plurality of R and R ¹ are present in the molecule, these may be the same or different from each other, and are preferably the same in terms of synthesis suitability.

In the above formulas, R represents a partial structure shown below. R ¹ has the same meaning as described above. When a plurality of R and R ¹ are present in the molecule, these may be the same or different from each other, and are preferably the same in terms of synthesis suitability.

In the present invention, silica particles, titanium oxide particles, aluminum oxide particles, and the like can also be used as the compound (I). These particles can react with a specific polymer to introduce a group represented by the above formula (I) into the polymer. For example, -SiOH is introduced by the reaction between silica particles and a specific polymer.
Other examples of titanium coupling agents include Ajinomoto Fine Techno Co., Ltd. Preneact, Matsumoto Fine Chemical Co., Ltd. Titanium Tetraisopropoxide, Nippon Soda Co., Ltd. Titanium-I-propoxybis (acetylacetonate) titanium. An example of the aluminate coupling agent is acetoalkoxyaluminum diisopropylate.

In this invention, said compound (I) may be used individually by 1 type, and may use 2 or more types together.
Compound (I) is preferably a compound having a molecular weight of 100 to 10,000, more preferably a compound having a molecular weight of 100 to 8,000, and still more preferably a compound having a molecular weight of 100 to 5,000.
In the present invention, the content of the compound (I) contained in the relief forming layer and the resin composition for laser engraving is preferably 0.1 to 80% by weight, more preferably 1 to 40% by weight in terms of solid content. %, More preferably 5 to 30% by weight.

In the present invention, the mechanism of action in which the relief forming layer contains a polymer having a group represented by the above formula (I) is not clear, but is estimated as follows. In the following description, the case where a compound in which M is Si is used as the compound (I) will be described, but the same applies to the case where a compound or the like in which M is Ti is used.
The hydroxyl group (—OH) and the like in the specific polymer in which the R ¹ group or R ² group of the compound (I) (provided that the R ² group is a halogen atom or —OR ³ ) coexist with alcohol An exchange reaction occurs, and as a result, the molecules of the specific polymer are three-dimensionally cross-linked by the compound (I). In addition, a group represented by the formula (I) is introduced into the polymer. As a result, (I) the effect of improving the rinsing property of the engraving residue generated by laser engraving with respect to the alkaline rinsing liquid, and (II) the elasticity of the film when the resin composition is formed is improved, and the plastic deformation is less likely to occur. An effect is obtained. (II) The improvement in film elasticity brings about the effect that, in the present invention, when the resin composition is applied to the relief forming layer, the ink transferability and printing durability of the formed printing plate are improved.

(I) About the rinse improvement effect, since the molecular weight of the high molecular compound itself which comprises the film | membrane which consists of a resin composition before engraving becomes large by having bridge | crosslinked binders with compound (I), it is laser. The engraving residue generated by engraving also becomes a powdered residue in which stickiness due to a low molecular weight liquid component is suppressed, and it is considered that a rinse property that can be easily removed is obtained. Moreover, since the group represented by the above formula (I) is ionized by an alkaline rinsing liquid and becomes hydrophilic, it is presumed that the detergency is further improved.
In addition, as a result of specific polymers being directly cross-linked via compound (I), a three-dimensional cross-linked structure is formed in the molecule to satisfy the requirements for rubber elasticity, and apparently behaves like rubber. (II) It is considered that the effect of improving the film elasticity can be obtained. Accordingly, when a relief forming layer is produced by forming the resin composition in the present invention, the film elasticity of the resulting relief layer is improved, and even in a state where repeated printing pressure is applied in printing over a long period of time, plasticity It is presumed that deformation is suppressed, excellent ink transferability is realized, and printing durability is improved.

Thus, the resin composition containing compound (I) and the specific polymer forms a crosslinked structure by reacting compound (I) with the hydroxyl group in the specific polymer during preparation of the composition and film formation. In this way, various excellent physical properties are expressed.
It can be confirmed by the following method that the reaction between the compound (I) and the specific polymer proceeds in the resin composition and a crosslinked structure is formed.
The crosslinked film can be identified using “solid ¹³ C-NMR”.
Atoms capable of reacting with compound (I) such as OH groups in a specific polymer and / or carbon atoms directly bonded to the group change the electronic environment before and after the reaction with compound (I). The peak position changes. A peak derived from an atom that can react with the compound (I) such as an unreacted OH group and / or a carbon atom directly bonded to the group, and a peak of a carbon atom that reacts with the compound (I) to become an alkoxy group. By comparing the strength before and after the reaction, it is possible to know that the alcohol exchange reaction is actually progressing and the approximate reaction rate. In addition, since the degree of the change of the peak position varies depending on the structure of the specific polymer used, this change is a relative index.
Another method is to immerse the membrane before and after the reaction in a solvent and visually observe the change in the appearance of the membrane, and it is possible to know the progress of the reaction (crosslinking reaction) by this method.
Specifically, when the resin composition is formed into a film, the film is immersed in acetone at room temperature for 24 hours, and the appearance is visually observed. Even when the crosslinked structure is not formed or slightly formed, In such a case, the film dissolves in acetone and deforms to such an extent that the appearance is not retained, or dissolves and a solid matter cannot be visually confirmed. The appearance of the film remains as it was before immersion in acetone.

(Component D) Polymerizable Compound In the present invention, from the viewpoint of forming a crosslinked structure in the relief forming layer to form a crosslinked relief forming layer, the relief forming layer is formed from (Component D) polymerizable. It is preferable to contain a compound.
The polymerizable compound that can be used here can be arbitrarily selected from compounds having at least 1, preferably 2 or more, more preferably 2 to 6 ethylenically unsaturated double bonds.

Hereinafter, a monofunctional monomer having one ethylenically unsaturated double bond in the molecule and a polyfunctional monomer having two or more such bonds in the molecule, which are used as the polymerizable compound, will be described.
Since the crosslinked relief forming layer according to the present invention needs to have a crosslinked structure in the film, a polyfunctional monomer is preferably used. The molecular weight of these polyfunctional monomers is 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.

  Further, the total content of the (Component D) polymerizable compound in the relief forming layer is preferably 10% by weight to 60% by weight, and preferably 15% by weight with respect to the total solid content from the viewpoint of flexibility and brittleness of the crosslinked film. The range of% to 45% by weight is more preferable.

(Component E) Alcohol exchange reaction catalyst In the present invention, the resin composition includes (Component A-1) an alcohol exchange reaction in order to promote the reaction between the specific polymer and (Component C) compound (I). It is preferable to contain a catalyst.
(Component E) The alcohol exchange reaction catalyst can be applied without limitation as long as it is a commonly used reaction catalyst.
Hereinafter, the (component E-1) acid or basic catalyst and the (component E-2) metal complex catalyst, which are typical alcohol exchange reaction catalysts, will be sequentially described.

(Component E-1) Acid or basic catalyst As the catalyst, an acid or a basic compound is used as it is or dissolved in a solvent such as water or an organic solvent (hereinafter referred to as an acidic catalyst and a base, respectively). (Referred to as a catalytic catalyst). The concentration at the time of dissolving in the solvent is not particularly limited, and may be appropriately selected according to the characteristics of the acid or basic compound used, the desired content of the catalyst, and the like.
The type of acidic catalyst or basic catalyst is not particularly limited. Specifically, examples of the acidic catalyst include hydrogen halides such as hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, hydrogen sulfide, perchloric acid, hydrogen peroxide, carbonic acid, Examples of the basic catalyst include carboxylic acids such as formic acid and acetic acid, substituted carboxylic acids obtained by substituting R of the structural formula represented by RCOOH with other elements or substituents, sulfonic acids such as benzenesulfonic acid, and phosphoric acid. Include ammoniacal bases such as aqueous ammonia and amines such as ethylamine and aniline. From the viewpoint of promptly promoting the alcohol exchange reaction in the membrane, methanesulfonic acid, p-toluenesulfonic acid, pyridinium p-toluenesulfonate, phosphoric acid, phosphonic acid, and acetic acid are preferable, and methanesulfonic acid, p is particularly preferable. -Toluenesulfonic acid and phosphoric acid.

(Component E-2) Metal complex catalyst (Component E-2) Metal complex catalyst used as an alcohol exchange reaction catalyst in the present invention is preferably a metal element selected from Groups 2A, 3B, 4A and 5A of the periodic table And β-diketone, ketoester, hydroxycarboxylic acid or ester thereof, amino alcohol, and enolic active hydrogen compound.
Furthermore, among the constituent metal elements, 2A group elements such as Mg, Ca, St and Ba, 3B group elements such as Al and Ga, 4A group elements such as Ti and Zr, and 5A group elements such as V, Nb and Ta Are preferable, and each form a complex having an excellent catalytic effect. Among them, complexes obtained from Zr, Al and Ti are excellent and preferred (such as ethyl orthotitanate).
These are excellent in stability in aqueous coating solutions and in the gelation promoting effect in the sol-gel reaction at the time of heat drying. Acetonato) titanium complex and zirconium tris (ethyl acetoacetate) are preferred.

In the present invention, in the relief forming layer and the resin composition for laser engraving, only one type of (Component E) alcohol exchange reaction catalyst may be used, or two or more types may be used in combination.
The content of the (component E) alcohol exchange reaction catalyst in the relief forming layer and the resin composition for laser engraving is preferably 0.01 to 20% by weight with respect to the (component A-1) specific polymer. More preferably, it is 1 to 10% by weight.

(Component F) Polymerization initiator In the present invention, the relief forming layer and the resin composition for laser engraving preferably contain (Component F) a polymerization initiator.
A well-known thing can be used for a polymerization initiator without a restriction | limiting. Hereinafter, although the radical polymerization initiator which is a preferable polymerization initiator is explained in full detail, this invention is not restrict | limited by these description.

  In the present invention, preferred radical polymerization initiators include (a) aromatic ketones, (b) onium salt compounds, (c) organic peroxides, (d) thio compounds, (e) hexaarylbiimidazole compounds, (F) ketoxime ester compound, (g) borate compound, (h) azinium compound, (i) metallocene compound, (j) active ester compound, (k) compound having carbon halogen bond, (l) azo compound, etc. Is mentioned. Specific examples of the above (a) to (l) are given below, but the present invention is not limited to these.

  In the present invention, from the viewpoint of engraving sensitivity and a good relief edge shape when applied to a relief forming layer of a relief printing plate precursor, (c) an organic peroxide and (l) an azo compound are more Preferably, (c) an organic peroxide is particularly preferable.

(A) aromatic ketones, (b) onium salt compounds, (d) thio compounds, (e) hexaarylbiimidazole compounds, (f) ketoxime ester compounds, (g) borate compounds, (h) azinium compounds , (I) metallocene compounds, (j) active ester compounds, and (k) compounds having a carbon halogen bond include the compounds listed in paragraphs [0074] to [0118] of JP-A-2008-63554. It can be preferably used.
The polymerization initiator can be roughly classified into a photopolymerization initiator and a thermal polymerization initiator. In the present invention, a thermal polymerization initiator is preferably used from the viewpoint of improving the degree of crosslinking. As the thermal polymerization initiator, (c) an organic peroxide and (l) an azo compound are preferably used. In particular, the following compounds are preferred.

(C) Organic peroxide Preferred as a radical polymerization initiator that can be used in the present invention (c) As the organic peroxide, 3,3′4,4′-tetra- (tertiarybutylperoxycarbonyl) benzophenone 3,3′4,4′-tetra- (tertiary amyl peroxycarbonyl) benzophenone, 3,3′4,4′-tetra- (tertiary hexylperoxycarbonyl) benzophenone, 3,3′4,4 '-Tetra- (tertiary octylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (cumylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (p-isopropylcumylper Examples include peroxide esters such as oxycarbonyl) benzophenone and di-tertiary butyl diperoxyisophthalate. wear.

(L) Azo-based compound Preferred as a radical polymerization initiator that can be used in the present invention (l) As the azo-based compound, 2,2′-azobisisobutyronitrile, 2,2′-azobispropionitrile, 1 , 1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′- Azobis (4-methoxy-2,4-dimethylvaleronitrile), 4,4′-azobis (4-cyanovaleric acid), dimethyl 2,2′-azobisisobutyrate, 2,2′-azobis (2-methylpropionamide) Oxime), 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2- Hydro Ethyl] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2 '-Azobis (N-cyclohexyl-2-methylpropionamide), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (2,4,4- Trimethylpentane) and the like.

In the present invention, (Component F) polymerization initiator may be used alone or in combination of two or more.
The content of (Component F) the polymerization initiator is preferably 0.01 to 10% by weight, more preferably 0.1 to 3% by weight, based on the total solid content of the relief forming layer and the resin composition for laser engraving. By setting the content of the polymerization initiator to 0.01% by weight or more, the effect of adding this is obtained, and the crosslinkable relief forming layer is rapidly crosslinked. Further, when the content is 10% by weight or less, other components are not deficient, and printing durability sufficient for use as a relief printing plate can be obtained.

[Other additives]
(Component G) Plasticizer In the present invention, the relief forming layer and the resin composition for laser engraving preferably contain (Component G) a plasticizer. The plasticizer has a function of softening a film formed of the resin composition for laser engraving and needs to be compatible with the polymer.
As the plasticizer, for example, dioctyl phthalate, didodecyl phthalate, tributyl citrate, polyethylene glycols, polypropylene glycol (monool type or diol type), polypropylene glycol (monool type or diol type) are preferably used.

In the present invention, the resin composition for laser engraving is more preferably added with nitrocellulose or a highly thermally conductive substance as an additive for improving engraving sensitivity. Since nitrocellulose is a self-reactive compound, it generates heat during laser engraving and assists in the thermal decomposition of coexisting polymers such as hydrophilic polymers. As a result, it is estimated that the engraving sensitivity is improved. The highly heat conductive material is added for the purpose of assisting heat transfer, and examples of the heat conductive material include inorganic compounds such as metal particles and organic compounds such as a conductive polymer. As the metal particles, the conductive polymer is preferably a gold fine particle, a silver fine particle, or a copper fine particle having a particle size of from micrometer order to several nanometer order. It is done.
Moreover, the sensitivity at the time of photocuring the resin composition for laser engraving can be further improved by using a co-sensitizer.
Furthermore, it is preferable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the polymerizable compound during the production or storage of the composition.
Colorants such as dyes or pigments may be added for the purpose of coloring the resin composition for laser engraving. Thereby, properties such as the visibility of the image portion and the suitability of the image density measuring device can be improved.
Furthermore, in order to improve the physical properties of the cured film of the resin composition for laser engraving, a known additive such as a filler may be added.

〔solvent〕
In the present invention, the solvent used in preparing the resin composition is mainly an aprotic organic compound from the viewpoint of promptly proceeding the reaction between (Component C) Compound (I) and (Component A-1) the specific polymer. It is preferable to use a solvent. More specifically, it is preferable to use aprotic organic solvent / protic organic solvent = 100/0 to 50/50 (weight ratio). More preferably, it is 100 / 0-70 / 30, Most preferably, it is 100 / 0-90 / 10.
Preferred specific examples of the aprotic organic solvent include 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 and dimethyl sulfoxide.
Preferred specific examples of the protic organic solvent are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, ethylene glycol, diethylene glycol, and 1,3-propanediol.

  In the present invention, the relief printing plate precursor for laser engraving has a relief forming layer made of the resin composition for laser engraving containing the components as described above. The relief forming layer is preferably provided on the support.

  If necessary, the relief printing plate precursor for laser engraving may further have an adhesive layer between the support and the relief forming layer, and a slip coat layer and a protective film on the relief forming layer.

<Relief forming layer>
The relief forming layer is a layer made of the resin composition for laser engraving. A resin composition containing component A and component B is used as the resin composition for laser engraving. In the present invention, as the relief printing plate precursor for laser engraving, in addition to the introduction of the group represented by the crosslinked structure and the formula (I) with the (component A-1) specific polymer and the (component C) compound (I) Further, those having a relief forming layer imparted with a further crosslinkable function by further containing (Component D) a polymerizable compound and (Component F) a polymerization initiator are preferable.

  As a plate making aspect of a relief printing plate using a relief printing plate precursor for laser engraving, a relief printing plate precursor having a crosslinked relief forming layer cured by crosslinking a relief forming layer is prepared, and then the cured crosslinked relief forming layer ( A relief printing plate is produced by forming a relief layer by laser engraving a hard relief forming layer). By crosslinking the relief forming layer, wear of the relief layer during printing can be prevented, and a relief 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 above components for the relief forming layer into a sheet shape or a sleeve shape. The relief forming layer is usually provided in the form of a support, which will be described later. However, the relief forming layer may be directly formed on the surface of a member such as a cylinder provided in an apparatus for plate making and printing, or may be arranged and fixed there. it can.
Hereinafter, the case where the relief forming layer is formed into a sheet shape will be mainly described as an example.

<Support>
The support that can be used for the relief printing plate precursor will be described.
The material used for the support for the relief printing plate precursor is not particularly limited, but materials having high dimensional stability are preferably used. For example, metals such as steel, stainless steel, and aluminum, polyester (for example, PET, PBT, PAN), and poly Examples thereof include plastic resins such as vinyl chloride, synthetic rubbers such as styrene-butadiene rubber, and plastic resins reinforced with glass fibers (such as epoxy resins and phenol resins). As the support, a PET (polyethylene terephthalate) 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.
Also, a relief printing plate prepared by applying a crosslinkable resin composition for laser engraving and curing from the back surface (the surface opposite to the surface on which laser engraving is performed, including a cylindrical one) with light or heat. In the original plate, the support is not essential because the back side of the cured resin composition for laser engraving functions as a support.

<Adhesive layer>
An adhesive layer may be provided between the relief forming layer and the support for the purpose of enhancing the adhesive force between the two layers. As a material (adhesive) that can be used for the adhesive layer, for example, I.I. Those described in the edition of Skeist, “Handbook of Adhesives”, the second edition (1977) can be used.

<Protective film, slip coat layer>
For the purpose of preventing scratches and dents on the surface of the relief forming layer, a protective film may be provided on the surface of the relief forming layer. The thickness of the protective film is preferably 25 to 500 μm, more preferably 50 to 200 μm. As the protective film, for example, a polyester film such as PET (polyethylene terephthalate) or a polyolefin film such as PE (polyethylene) or PP (polypropylene) can be used. The surface of the film may be matted. When providing a protective film on a relief forming layer, the protective film must be peelable.

  When the protective film cannot be peeled or when it is 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

<Preparation method of relief printing plate precursor>
Next, a method for producing a relief printing plate precursor will be described.
The formation of the relief forming layer in the relief printing plate precursor is not particularly limited. For example, a relief forming layer coating liquid composition (containing a resin composition for laser engraving) is prepared, and this relief forming layer is used. The method of melt-extruding on a support after removing a solvent from a coating liquid composition is mentioned. Alternatively, the relief forming layer coating solution composition may be cast on a support and dried in an oven to remove the solvent from the coating solution composition.
Thereafter, a protective film may be laminated on the relief forming layer as necessary. Lamination can be performed by pressure-bonding the protective film and the relief forming layer with a heated calendar roll or the like, or by bringing the protective film into close contact with the relief forming layer impregnated with a small amount of solvent on the surface.
When a protective film is used, a method of first laminating a relief forming layer on the protective 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 providing a slip coat layer, it can respond by using the protective film which apply | coated the slip coat layer.

  The coating composition for the relief forming layer is prepared, for example, by dissolving a binder polymer, a photothermal conversion agent, and, as an optional component, a plasticizer in an appropriate solvent, and then dissolving a polymerizable compound and a polymerization initiator. Can be manufactured. Since most of the solvent components need to be removed at the stage of producing the relief printing plate precursor, low-molecular alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, propylene glycol monomethyl ether, which are easily volatile) are used as the solvent. It is preferable to keep the total amount of solvent added as low as possible by adjusting the temperature.

Here, in the present invention, in the case of a relief printing plate precursor, it refers to the state in which the relief forming layer is crosslinked as described above. In the method of crosslinking the relief forming layer, the step of crosslinking the relief forming layer by actinic ray irradiation and / or heating (the step (1) in the preparation step in the plate making method of the relief printing plate of the present invention described later) is performed. Is preferred.
The term “crosslinking” as used herein is a concept including a crosslinking reaction for linking polymers, and a relief caused by a polymerization reaction between polymerizable compounds having an ethylenically unsaturated bond or a reaction between a polymer and a polymerizable compound. It is a concept that includes the curing reaction of the formation layer.

  The thickness of the relief forming layer in the relief printing plate precursor is preferably from 0.05 mm to 10 mm, more preferably from 0.05 mm to 7 mm, particularly preferably from 0.05 mm to 3 mm.

(Relief printing plate and plate making method)
In the present invention, a method for making a relief printing plate using a relief printing plate precursor includes (1) a step of preparing a relief printing plate precursor having a relief forming layer, and (2) an engraving step of laser engraving the relief printing plate precursor. ,including.
The engraving step is a step of engraving using an exposure head in which at least two semiconductor lasers having wavelengths of 700 nm to 1,300 nm are arranged, and in the engraving step, 10 m / s or more is applied to the laser irradiation portion. Gas is blown at a wind speed, and the blowing angle of the gas is 0 ° or more and less than 90 ° when the angle parallel to the printing plate and the direction opposite to the drawing direction is 0 °.

In the preferable plate making method of the relief printing plate in the present invention, the following step (3) is further included after step (2), and steps (4) and (5) may be included as necessary.
Step (3): A step of rinsing the engraved surface of the relief layer after engraving with a rinsing liquid that is an aqueous solution having a pH of 9 or more (rinsing step).
Step (4): A step of drying the engraved relief layer (drying step).
Step (5): A step of imparting energy to the relief layer after engraving and further crosslinking the relief layer (post-crosslinking step).

In the production of the relief printing plate precursor in the step (1), it is preferable to have a step of crosslinking the relief forming layer, and the crosslinking is performed by irradiation with actinic rays and / or heat.
In the cross-linking of the relief forming layer, when the step of cross-linking by light and the step of cross-linking by heat are used in combination, these steps may be simultaneous with each other or separate steps.

The relief forming layer contains (Component A) a binder polymer and (Component B) a photothermal conversion agent, and preferably (Component C) Compound (I), (Component F) a polymerization initiator, and (Component D). ) It contains a polymerizable compound, and in step (1), the polymerizable compound is polymerized by the action of a polymerization initiator, and in addition to the crosslinked structure of the binder polymer and compound (I), crosslinks are formed at a higher density. Thus, the relief forming layer is a step of forming a cured relief forming layer (crosslinked relief forming layer).
The polymerization initiator is preferably a radical generator, and the radical generator is roughly classified into a photopolymerization initiator and a thermal polymerization initiator depending on whether the trigger for generating radicals is light or heat.

When the relief-forming layer contains a photopolymerization initiator, the relief-forming layer can be crosslinked by irradiating the relief-forming layer with an actinic ray that triggers the photopolymerization initiator (step of crosslinking by light ).
The irradiation with actinic light is generally performed on the entire surface of the relief forming layer. Visible light, ultraviolet light, or an electron beam is mentioned as actinic light, but ultraviolet light is the most common. If the substrate side for immobilizing the relief forming layer, such as a support for the relief forming layer, is the back surface, the surface may be irradiated only with active light, but the support used is transparent to transmit active light. If it is a film, it is also preferable to irradiate actinic rays 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, actinic rays may be irradiated after the crosslinkable relief forming layer is covered with a vinyl chloride sheet and evacuated.

  When the relief forming layer contains a thermal polymerization initiator (the above-mentioned photopolymerization initiator can also be a thermal polymerization initiator), the relief forming layer is heated by heating the relief printing plate precursor for laser engraving. It can be crosslinked (step of crosslinking by heat). Examples of the heating means 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 the heated roll for a predetermined time.

In the case where the step (1) is a step of crosslinking by light, an apparatus for irradiating actinic rays is relatively expensive, but the printing plate precursor does not become high temperature. rare.
When step (1) is a step of crosslinking by heat, there is an advantage that an extra expensive apparatus is not required, but since the printing plate precursor becomes high temperature, the thermoplastic polymer that becomes flexible at high temperature is being heated. The raw materials to be used must be carefully selected.
A thermal polymerization initiator can be added during the thermal crosslinking. As the thermal polymerization initiator, it can be used as a commercial thermal polymerization initiator for free radical polymerization. Examples of such a thermal polymerization initiator include a compound containing a suitable peroxide, hydroperoxide, or azo group. Representative vulcanizing agents can also be used for crosslinking. Thermal crosslinking can also be performed by adding a heat-curable resin, such as an epoxy resin, as a crosslinking component to the layer.

As a crosslinking method of the relief forming layer in the step (1), crosslinking by heat is preferable from the viewpoint that the relief forming layer can be uniformly cured (crosslinked) from the surface to the inside.
By crosslinking the relief forming layer, there is an advantage that the relief formed first after laser engraving becomes sharp, and second, the adhesiveness of engraving residue generated during laser engraving is suppressed. When an uncrosslinked relief-forming layer is laser engraved, unintended portions are likely to melt and deform due to residual heat that has propagated around the laser-irradiated portion, and a sharp relief layer may not be obtained. In addition, as a general property of a material, a material having a low molecular weight tends to be liquid rather than solid, that is, the adhesiveness tends to be strong. The engraving residue generated when engraving the relief forming layer tends to become more tacky as more low-molecular materials are used. Since the polymerizable compound which is a low molecule becomes a polymer by crosslinking, the generated engraving residue tends to be less tacky.

In the present invention, the crosslinking density of the crosslinked relief forming layer is preferably 10 × 10 ² mol / mL or more. By setting the crosslinking density to 10 × 10 ² mol / mL or more, the influence of the heat of the adjacent laser is suppressed, and a sharp image can be formed.
The crosslinking density of the crosslinked relief forming layer is more preferably 10 × 10 ² to 10 × 10 ⁶ mol / mL, and further preferably 50 × 10 ² to 10 × 10 ⁵ mol / mL.
In the present invention, the crosslinking density is calculated from the absolute temperature (K) at T: equilibrium storage elastic modulus and the measured value of E: equilibrium storage elastic modulus using the following equation for rubber elasticity.
n = E / 3RT
Where n is the crosslink density (mol / mL), R is the gas constant (8.314 × 10 ⁷ erg.deg / mol), T is the absolute temperature (K), and E is the equilibrium storage elasticity. Rate (dyne / cm ² ).
When the molecular weight between cross-linking points is small and the number of cross-linking points is large, it can be said that the equilibrium storage elastic modulus is high and the cross-linking density is high.

Step (2) is a step of forming a relief layer by laser engraving the crosslinked relief forming layer.
The engraving step is a step of engraving using an exposure head in which at least two semiconductor lasers having wavelengths of 700 nm to 1,300 nm are arranged, and in the engraving step, a wind speed of 10 m / s or more is applied to the laser irradiation portion. When the gas is blown and the angle of blowing the gas is 0 °, which is parallel to the plate surface and opposite to the drawing direction, is 0 ° or more and less than 90 °.

Specifically, the relief layer is formed by engraving the crosslinked relief forming layer with a laser beam corresponding to the image to be formed. Preferably, the step of controlling the laser head with a computer based on the digital data of the image to be formed and irradiating the crosslinked relief forming layer with scanning. When irradiated with an infrared laser, the molecules in the crosslinked relief forming layer undergo molecular vibrations and generate heat. When a high-power laser is used as the infrared laser, a large amount of heat is generated in the laser irradiation portion, and molecules in the photosensitive layer are molecularly cut or ionized to be selectively removed, that is, engraved. At this time, since the exposed region also generates heat due to the photothermal conversion agent in the relief forming layer, the heat generated by the photothermal conversion agent also promotes this removability.
The advantage of laser engraving is that the engraving depth can be set arbitrarily, so that the structure can be controlled three-dimensionally. For example, the relief can be prevented from falling down by printing pressure by engraving the shallow halftone dot printing part or with a shoulder, and engraving deeply the groove part that prints fine punched characters. Therefore, it becomes difficult for the ink 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 maximum absorption wavelength of the photothermal conversion agent, heat generation from the above-described photothermal conversion agent is efficiently performed, so that a more sensitive and sharp relief layer can be obtained.
As an infrared laser used for engraving, a semiconductor laser is used from the viewpoint of productivity, cost, and the like, and among them, a semiconductor infrared laser with a fiber described in detail below is used.

[Plate making equipment with semiconductor laser]
In general, a semiconductor laser can be downsized with high efficiency and low cost in laser oscillation compared to a CO ₂ laser. Moreover, since it is small, it is easy to form an array. The control of the beam diameter is performed using an imaging lens and a specific optical fiber. The semiconductor laser with fiber is effective for image formation in the present invention because it can efficiently output laser light by further attaching an optical fiber. 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 semiconductor lasers are described in “Laser Handbook 2nd Edition” edited by Laser Society, Practical Laser Technology and Electronic Communication Society.
In addition, a plate making apparatus equipped with a fiber-coupled semiconductor laser that can be suitably used in a method for producing a relief printing plate using a relief printing plate precursor is disclosed in JP-A-2009-172658 and JP-A-2009-. It is described in detail in Japanese Patent No. 214334, and can be used for making a relief printing plate.

In the present invention, the semiconductor laser used for laser engraving has a wavelength of 700 nm to 1,300 nm, preferably 800 nm to 1,200 nm, more preferably 860 nm to 1,200 nm, 900 nm to 1, More preferably, it is 100 nm.
Since the band gap of GaAs is 860 nm at room temperature, an AlGaAs-based active layer is generally preferably used in a region less than 860 nm. On the other hand, a semiconductor active layer material of InGaAs type is used at 860 nm or more. In general, since Al is easily oxidized, a semiconductor laser having an InGaAs-based material as an active layer is more reliable than an AlGaAs-based material, and therefore, 860 nm to 1,200 nm is preferable.
Furthermore, as a practical semiconductor laser, considering not only the active layer material but also the composition of the clad material, a semiconductor laser having an InGaAs-based material in the active layer has a wavelength of 900 nm to 1,100 nm as a more preferable aspect. It is easy to obtain a higher output and higher reliability in the range. Therefore, it is easy to achieve high productivity, which is the effect of the present invention, by using a fiber-coupled semiconductor laser having an active layer of an InGaAs-based material having a wavelength of 900 nm to 1,100 nm.
Furthermore, as a practical semiconductor laser, considering not only the active layer material but also the composition of the clad material, a semiconductor laser having an InGaAs-based material in the active layer has a wavelength of 900 nm to 1,100 nm as a more preferable aspect. It is easy to obtain a higher output and higher reliability in the range. Therefore, it is easy to achieve low cost and high productivity by using a fiber-coupled semiconductor laser having an active layer of an InGaAs-based material having a wavelength of 900 nm to 1,100 nm.
In order to realize a laser engraving relief printing system that is inexpensive and highly productive and has good image quality, a relief printing plate precursor provided with a relief forming layer using a resin composition for laser engraving as described later is used. In addition, it is preferable to use a semiconductor laser with a specific wavelength as described above and a fiber-attached semiconductor laser.

  By using a semiconductor laser with a fiber, in the control of the shape to be engraved, the engraving area can be changed by changing the beam shape of the semiconductor laser with fiber or changing the amount of energy supplied to the laser without changing the beam shape. This also has the advantage that the shape of the can be changed.

  FIG. 1 is a block diagram of a plate making apparatus preferably used in the present invention. The plate making apparatus 11 in FIG. 1 fixes a sheet-like relief printing plate precursor F to the outer peripheral surface of a drum 50 having a cylindrical shape, and rotates the drum 50 in the direction of arrow R (main scanning direction) in FIG. A plurality of laser beams corresponding to the image data of the image to be engraved (recorded) on the relief printing plate precursor F are emitted from the exposure head 30 of the laser recording device toward the relief printing plate precursor F, and the exposure head 30 is moved. By scanning at a predetermined pitch in the sub-scanning direction (arrow S direction in FIG. 1) orthogonal to the main scanning direction, a two-dimensional image is engraved (recorded) on the surface of the relief printing plate precursor F at high speed.

  A laser recording apparatus used in the plate making method of FIG. 1 includes a light source unit 20 that generates a plurality of laser beams, an exposure head 30 that irradiates the relief printing plate precursor F with a plurality of laser beams generated by the light source unit 20, and And an exposure head moving unit 40 that moves the exposure head 30 along the sub-scanning direction.

The light source unit 20 includes a plurality of semiconductor lasers 21 (a total of 32 in this case), and the light of each semiconductor laser 21 is individually sent to the optical fiber array unit 300 of the exposure head 30 via the optical fibers 22 and 70, respectively. Is transmitted.
In this example, a broad area semiconductor laser (wavelength 915 nm) is used as the semiconductor laser 21, and these semiconductor lasers 21 are arranged side by side on the light source substrate 24. Each semiconductor laser 21 is individually coupled to one end of an optical fiber 22, and the other end of the optical fiber 22 is connected to an adapter of an SC type optical connector 25.
The adapter substrate 23 that supports the SC type optical connector 25 is vertically attached to one end of the light source substrate 24. Further, an LD driver substrate 27 on which an LD driver circuit (not shown) for driving the semiconductor laser 21 is mounted is attached to the other end of the light source substrate 24. Each semiconductor laser 21 is connected to a corresponding LD driver circuit via an individual wiring member 29, and each semiconductor laser 21 is individually driven and controlled.

  The exposure head 30 includes an optical fiber array unit 300 that collects and emits laser beams emitted from the plurality of semiconductor lasers 21. The light emitting section (not shown in FIG. 1, reference numeral 280 in FIG. 2) of the optical fiber array section 300 has a structure in which the emitting ends of the 32 optical fibers 70 guided from the respective semiconductor lasers 21 are arranged in a line. (See FIG. 3).

  Further, in the exposure head 30, a collimator lens 32, an opening member 33, and an imaging lens 34 are arranged in order from the light emitting unit side of the optical fiber array unit 300. An imaging optical system is configured by the combination of the collimator lens 32 and the imaging lens 34. The opening member 33 is disposed so that the opening is positioned at the far field when viewed from the optical fiber array unit 300 side. As a result, the same light quantity limiting effect can be given to all the laser beams emitted from the optical fiber array unit 300.

  The exposure head moving unit 40 is provided with a ball screw 41 and two rails 42 arranged so that the longitudinal direction is along the sub-scanning direction, and a sub-scanning motor (not shown in FIG. 1) that rotationally drives the ball screw 41. 6 is operated, the exposure head 30 disposed on the ball screw 41 can be moved in the sub-scanning direction while being guided by the rail 42. The drum 50 can be driven to rotate in the direction of the arrow R in FIG. 1 by operating a main scanning motor (not shown in FIG. 1, reference numeral 51 in FIG. 6), thereby performing main scanning.

  FIG. 2 is a configuration diagram of the optical fiber array unit 300, and FIG. 3 is an enlarged view of the light emitting unit 280 (viewed in the direction of arrow A in FIG. 2). As shown in FIG. 3, in the light emitting section 280 of the optical fiber array section 300, optical fibers 70 that emit 32 lights at regular intervals are arranged in a straight line.

  The optical fiber array unit 300 has a base (V-groove substrate) 302, and the base 302 is formed so that the same number of semiconductor lasers 21, that is, 32 V-shaped grooves 282 are adjacent to each other at a predetermined interval. Has been. One optical fiber end 71 of the other end of the optical fiber 70 is fitted into each V-shaped groove 282 of the base 302. Thereby, the optical fiber end group 301 arranged in a straight line is configured. Therefore, these multiple (32) laser beams are simultaneously emitted from the light emitting portion 280 of the optical fiber array portion 300.

  FIG. 4 is a schematic diagram of an imaging system of the optical fiber array unit 300. As shown in FIG. 4, the light emitting unit 280 of the optical fiber array unit 300 is exposed to the exposure surface (surface) of the relief printing plate precursor F at a predetermined imaging magnification by the imaging unit composed of the collimator lens 32 and the imaging lens 34. ) Form an image near the FA. In the present embodiment, the imaging magnification is set to 1/3, and, for example, the spot diameter of the laser beam LA emitted from the optical fiber end 71 having a core diameter of 105 μm is φ35 μm.

In the exposure head 30 having such an imaging system, the distance between adjacent fibers (L _{1 in} FIG. 3) of the optical fiber array unit 300 described in FIG. 3 and the optical fiber end group 301 when the optical fiber array unit 300 is fixed. By appropriately designing the inclination angle (angle θ in FIG. 5) in the arrangement direction (array direction), as shown in FIG. 5, the scanning line exposed by the laser beam emitted from the optical fiber arranged at the adjacent position The interval P ₁ of (main scanning line) K can be set to 10.58 μm (corresponding to a resolution of 2,400 dpi in the sub-scanning direction).
By using the exposure head 30 configured as described above, it is possible to simultaneously scan and expose a range of 32 lines (one swath).

FIG. 6 is a plan view showing an outline of a scanning exposure system in the plate making apparatus 11 shown in FIG. The exposure head 30 includes a focus position changing mechanism 60 and an intermittent feed mechanism 90 in the sub-scanning direction.
The focus position changing mechanism 60 has a motor 61 and a ball screw 62 that move the exposure head 30 back and forth with respect to the drum 50 surface. Under the control of the motor 61, the focus position can be moved about 300 μm in about 0.1 seconds. it can. The intermittent feed mechanism 90 constitutes the exposure head moving unit 40 described with reference to FIG. 1, and includes a ball screw 41 and a sub-scanning motor 43 that rotates the ball screw 41 as shown in FIG. The exposure head 30 is fixed to the stage 44 on the ball screw 41. Under the control of the sub-scanning motor 43, the exposure head 30 is swathed adjacent to the swath by one swath in the direction of the axis 52 of the drum 50 in about 0.1 seconds. Can intermittently feed up to minutes.

  In FIG. 6, reference numerals 46 and 47 denote bearings that rotatably support the ball screw 41. Reference numeral 55 denotes a chuck member that chucks the relief printing plate precursor F on the drum 50. The position of the chuck member 55 is a non-recording area where exposure (recording) by the exposure head 30 is not performed. While rotating the drum 50, the relief printing plate precursor F on the rotating drum 50 is irradiated with a laser beam of 32 channels from the exposure head 30 so that an exposure range 92 for 32 channels (one swath) is obtained. Exposure is performed without gaps, and engraving (image recording) of 1 swath width is performed on the surface of the relief printing plate precursor F. When the chuck member 55 passes in front of the exposure head 30 due to the rotation of the drum 50 (at the non-recording area of the relief printing plate precursor F), intermittent feeding is performed in the sub-scanning direction, and the next one swath is obtained. To expose. A desired image is formed on the entire surface of the relief printing plate precursor F by repeating such exposure scanning by intermittent feeding in the sub-scanning direction.

  In FIG. 3, an example of a beam arrangement in which 32 lines (one swath) of beams are arranged in one row in an oblique direction by the exposure head 30 having an optical fiber array arrangement in one row is shown. The arrangement is not limited to one row.

  FIG. 7 shows another example of the optical fiber array unit light source. The illustrated optical fiber array unit light source 500 includes optical fiber array units 501, 502, 503, and 504 combined in four rows. In the array of each column, 16 optical fibers 70 are arranged in a straight line, and a total of 64 optical fibers 70 are arranged in an oblique matrix in a total of four columns.

  As shown in FIG. 7, the channel numbers belonging to the optical fiber array unit 501 in the top row (first row) are 4M + 1 (M = 0, 1, 2,...) From the right end, and the channels belonging to the second row (reference numeral 502). The value of M is 4M + 2 from the right end, the number of the channel belonging to the third column (reference 503) is 4M + 3 from the right end, and the number of the channel belonging to the fourth lowermost row (reference 503) is 4M + 4 from the right end. The block is composed of 16 rows of 4 channels that share a common channel.

The adjacent fiber spacing (L _{1 in} FIG. 7) and the spacing (L _{2 in} FIG. 7) in the rows of the optical fiber array units 501, 502, 503, and 504 in each row, and the relative position in the row direction (FIG. L ₃₎ of 7, by further appropriately designing the inclination angle of the array units, the spacing of the scanning lines (main scanning lines) for exposing at the adjacent channel optical fiber, the right end of the channel (array blocks of four channels The interval between the scanning lines to be exposed can be set to be equal between the channel belonging to the upper row and the leftmost channel (channel belonging to the lower row of the array) adjacent to the block.
With the above configuration, a total of 64 lines of 1 swath can be scanned and exposed with 4 lines as a repeating unit.

In the present invention, as shown in FIG. 7, when a semiconductor laser having two or more rows is used, the distance between the laser rows (L _{2 in} FIG. 7) is preferably 20 μm or more. It is preferable that the distance between the laser arrays is 20 μm or more because engraving debris (scattered debris) generated at the time of engraving in the first row does not accumulate or float on the engraved portion in the second row, thereby reducing productivity.
The distance between the laser arrays is more preferably 20 to 300 μm, still more preferably 25 to 200 μm.

In this invention, in an engraving process, gas is sprayed with a wind speed of 10 m / s or more with respect to a laser irradiation part. By blowing the gas, it is possible to prevent the productivity from being lowered due to the shielding of the irradiation light by the dissipative material generated during exposure (during engraving) and the influence of engraving residue deposited on the relief printing plate precursor.
If the wind speed of the blowing gas is less than 10 m / s, the engraving residue deposited on the relief printing plate precursor is not sufficiently removed, and the productivity is lowered.
The wind speed is measured at a position 1 cm from the plate surface of the exposed portion of the relief printing plate precursor. The wind speed is measured by, for example, a thermal anemometer.
The wind speed is preferably 12 m / s or more and 200 m / s or less, more preferably 15 m / s or more and 170 m / s or less, and further preferably 20 m / s or more and 150 m / s or less.

This will be further described with reference to FIG. FIG. 8 is a side view of the plate making apparatus 11 shown in FIG. The plate surface of the relief printing plate precursor F is exposed by the laser irradiated from the exposure head 30 to form an engraving (recess) 80. Further, the engraving residue 81 of the crosslinked relief forming layer of the engraving portion is scattered by laser engraving.
In the present invention, gas is blown toward the exposure part (laser irradiation part). The gas blowing angle θ is 0 ° or more when the angle parallel to the printing plate and the direction opposite to the drawing direction is 0 °. It is less than 90 °. Here, “parallel to the plate surface” means the tangential direction when the plate surface is circular as shown in FIG.
In FIG. 8, an arrow A indicates a direction parallel to the printing plate and opposite to the drawing direction. The gas blowing angle θ is selected between the direction of arrow A (0 °) and the horizontal direction (90 °) of FIG. 8 which is the same as the laser irradiation direction. When the spray angle θ is less than 0 °, it is difficult to spray the exposed portion. When the spray angle θ is 90 ° or more, engraving residue is scattered to the unexposed portion and productivity is lowered.
The spray angle is preferably 0 to 80 °, and more preferably 0 to 60 °.

  Examples of the gas blowing method include a method of blowing gas from a cross roller fan disposed below the drum 50, a method of arranging an air blowing nozzle below the exposure head 30, and blowing the gas using compressed air to the exposure unit. Although illustrated, this invention is not limited to this.

  In the above description, the sheet-like relief printing plate precursor F is used, but a cylindrical relief printing plate precursor (sleeve type) can also be used.

(3) Rinse process Since the engraving residue is adhered to the engraving surface after the above step, it is preferable to perform a rinsing step of rinsing the engraving surface with a rinsing liquid that is an aqueous solution of pH 9 or more to wash away the engraving residue. . In addition, aqueous solution means the liquid which has water or water as a main component.
The pH of the rinse liquid is preferably 9 or higher, more preferably 10 or higher, and still more preferably 11 or higher. Moreover, it is preferable that the pH of a rinse liquid is 14 or less, More preferably, it is 13 or less, More preferably, it is 12.5 or less.
It is preferable that the pH of the rinsing liquid is 9 or more because sufficient rinsing properties (cleaning properties) can be obtained. Moreover, since pH is 12.5 or less, since handling is easy, it is especially preferable.

What is necessary is just to adjust pH using an acid (acidic compound) and a base (basic compound) suitably in order to make a rinse liquid into said pH range, and the acid and base to be used are not specifically limited.
The basic compound for adjusting the pH is not particularly limited, and a known basic compound can be used, but an inorganic basic compound is preferable, and an alkali metal salt compound and an alkaline earth metal salt are preferable. A compound is more preferable, and an alkali metal hydroxide is further preferable.
Examples of basic compounds include sodium hydroxide, ammonium, potassium, lithium, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, Examples include inorganic alkali salts such as ammonium, sodium carbonate, potassium, ammonium, sodium hydrogen carbonate, potassium, ammonium, sodium borate, potassium, and ammonium.
Further, when an acid is used for adjusting the pH, inorganic acids are preferred, for example, HCl, H ₂ SO _3, phosphoric acid, HNO ₃ is illustrated.

It is preferable that the rinse liquid contains a surfactant.
There is no restriction | limiting in particular as surfactant, A well-known surfactant can be used, Anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant etc. can be illustrated.
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, α-olefin sulfonates, dialkyl sulfosuccinates, alkyl diphenyl ether disulfonates, linear alkyl benzene sulfonates, Branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamides Sodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, fatty acid alkyl ester sulfate esters, alkyl sulfate esters, polio Siethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxy Examples thereof include ethylene alkylphenyl ether phosphate esters, partially saponified products of styrene-maleic anhydride copolymers, partially saponified products of olefin-maleic anhydride copolymers, naphthalene sulfonate formalin condensates, and the like.

Examples of the cationic surfactant include alkylamine salts and quaternary ammonium salts.
Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters , Pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters , Fatty acid diethanolamides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkyl Min, triethanolamine fatty acid esters, trialkylamine oxides, molecular weight of polypropylene glycol 200 to 5,000, trimethylolpropane, adduct of glycerin or sorbitol polyoxyethylene or polyoxypropylene, acetylene glycol, and the like.

Examples of amphoteric surfactants include carboxybetaine compounds, sulfobetaine compounds, phosphobetaine compounds, amine oxide compounds, or phosphine oxide compounds.
Fluorine-based and silicone-based nonionic surfactants can also be used in the same manner.
Surfactant may be used individually by 1 type, or may use 2 or more types together.
The amount of the surfactant used is not particularly limited, but is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, based on the total weight of the rinse liquid. .

The rinsing liquid for relief printing plate making of the present invention preferably contains water as a main component.
The rinsing liquid for relief printing plate making of the present invention may contain a water miscible solvent such as alcohols, acetone, tetrahydrofuran and the like as a solvent other than water.

The rinsing liquid for relief printing plate making of the present invention preferably contains an antifoaming agent.
As the antifoaming agent, a general silicon-based self-emulsifying type, emulsifying type, surfactant nonionic HLB (Hydrophile-Lipophile Balance) value of 5 or less can be used. Silicon antifoaming agents are preferred. Among them, an emulsified dispersion type and a solubilized type can 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 weight in the rinsing liquid for relief printing plate making.

The rinsing liquid for relief printing plate making of the present invention may contain a preservative, an inorganic acid, a chelating agent, and / or a solvent, if necessary.
As the preservative, the inorganic acid, the chelating agent, and the solvent, known ones can be used.

The usage amount of the rinsing liquid needs to cover at least the entire plate with the liquid. The amount used varies depending on the plate, but is preferably 10 ml / m ² or more, more preferably 50 ml / m ² or more, and further preferably 70 ml / m ² or more. Moreover, it is especially preferable that the usage-amount of a rinse liquid is 70-500 ml / m < ² > from the point of the cost of the amount of process liquids.
As a means of rinsing, a method of spraying high-pressure water, a method of brush-washing the engraving surface mainly in the presence of water with a known batch-type or transport-type brush-type washing machine as a photosensitive resin letterpress developing machine, etc. Is mentioned. According to the present invention, since most of the engraving residue on the plate surface is removed by blowing gas in the engraving process, the number of brush rubbing times in the rinsing step can be reduced, and the occurrence of scratches on the plate surface is suppressed. can do. Further, since the generated engraving residue has no slime or the like and is in a powder form, the residue is effectively removed by a water rinsing step, so that it is not necessary to use, for example, a rinsing liquid to which soap is added.

When the rinsing step (3) is performed on the engraved surface, it is preferable to add a step (4) for drying the engraved relief forming layer and volatilizing the rinsing liquid.
Furthermore, you may add the process (5) which further bridge | crosslinks a relief forming layer as needed. By performing the additional crosslinking step (5) (post-crosslinking treatment), the relief formed by engraving can be further strengthened.

As described above, a relief printing plate having a relief layer on the surface of an arbitrary substrate such as a support can be obtained.
The thickness of the relief layer of the relief printing plate is preferably from 0.05 mm to 10 mm, more preferably from 0.05 mm to 7 mm, from the viewpoint of satisfying various printability such as abrasion resistance and ink transferability. Hereinafter, it is particularly preferably 0.05 mm or more and 3 mm or less.

The Shore A hardness of the relief layer of the relief printing plate is preferably 50 ° or more and 90 ° or less.
When the Shore A hardness of the relief layer is 50 ° or more, even if the fine halftone dots formed by engraving are subjected to the strong printing pressure of the relief printing press, they do not collapse and can be printed normally. In addition, when the Shore A hardness of the relief layer is 90 ° or less, it is possible to prevent faint printing in a solid portion even in flexographic printing with a kiss touch.
The Shore A hardness in the present specification is a durometer (spring type) in which an indenter (called a push needle or indenter) is pushed and deformed on the surface of the object to be measured, and the amount of deformation (pushing depth) is measured and digitized. It is a value measured by a rubber hardness meter.

  In the present invention, the relief printing plate produced using the relief printing plate precursor can be printed using any of water-based inks, oil-based inks, and UV inks using a relief printing press, Also, printing with UV ink by a flexographic printing machine is possible. In the present invention, the relief printing plate obtained from the relief printing plate precursor is excellent in rinsing properties, there is no residual engraving residue, and the obtained relief layer is excellent in elasticity, so that the ink transfer property and printing durability are improved. It is excellent and can be printed for a long period of time without concern about plastic deformation of the relief layer and deterioration of printing durability.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.

(Preparation of relief printing plate precursor 1)
1. Preparation of relief printing plate precursor 1 for laser engraving <Preparation of resin composition 1 for laser engraving>
In a three-necked flask equipped with a stirring blade and a condenser tube, (Component A-1) “Denka Butyral # 3000-2” as a specific polymer (manufactured by Denki Kagaku Kogyo Co., Ltd., polyvinyl butyral derivative, Mw = 90,000) 40 parts by weight and 47 parts by weight of propylene glycol monomethyl ether acetate as a solvent were added and heated at 70 ° C. for 120 minutes with stirring to dissolve the polymer. Thereafter, the solution is brought to 40 ° C., and (Component G) 33.1 parts by weight of tricyclodecane dimethanol dimethacrylate as a plasticizer and (Component D) NK ester DCP (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polymerizable compound ) 10 parts by weight, (Component F) 1.6 parts by weight of Perbutyl Z (manufactured by NOF Corporation) as a polymerization initiator, (Component B) Carbon black (Show Black N110, Cabot Japan Co., Ltd.) as a photothermal conversion agent Made, DBP oil absorption 115ml / 100g) was added, and stirred for 30 minutes. Thereafter, (Component C) Compound (I) (S-15) (the structure is shown below. Trade name, available from Shin-Etsu Chemical Co., Ltd. as KBE-846) 15 parts by weight and (Component E) alcohol As an exchange reaction catalyst, 0.2 part by weight of diazabicycloundecene was added and stirred at 40 ° C. for 10 minutes. By this operation, a fluid relief forming layer coating solution (laser engraving resin composition) 1 was obtained.

<Preparation of relief printing plate precursor 1 for laser engraving>
A spacer (frame) having a predetermined thickness is placed on a PET substrate, and the relief-forming layer coating solution 1 obtained above is gently cast so as not to flow out of the spacer (frame). After drying for a time, a relief forming layer having a thickness of about 1 mm was provided to prepare a relief printing plate precursor 1 for laser engraving.

2. Preparation of relief printing plate precursors 2 to 9 for laser engraving For laser engraving in the same manner as in resin composition 1 for laser engraving, except that the addition amount (parts by weight) of each component used is changed as shown in Table 1. Resin compositions 2 to 9 were prepared.
Relief printing plate precursors 2 to 9 were produced using the prepared resin compositions for laser engraving 2 to 9 in the same manner as in the relief printing plate precursor 1.

The resulting relief printing plate precursor was subjected to plate making under the following conditions.
<Engraving conditions>
Plate making was performed using the plate making apparatus shown in FIG.
As the engraving conditions, a laser recording apparatus equipped with a fiber-coupled semiconductor laser (FC-LD) SDL-6390 (manufactured by JDSU, wavelength 915 nm) having a maximum output of 8.0 W was used. Under the conditions of scanning speed: 1,300 mm / sec and pitch setting: 2,400 DPI, concave lines and convex lines with a width of 100 μm were engraved every 100 μm in a 1 cm square.
The number of semiconductor lasers used and the number of rows are as shown in Tables 2 and 3. The number of lasers is the number per row.

<Blowing gas>
The gas was blown onto the exposed portion by blowing compressed air onto the plate surface at 40 m / sec with a hole nozzle 720 (manufactured by Sanwa Enterprise Co., Ltd.). The spraying angle (corresponding to θ in FIG. 8) was 0 ° parallel to the printing plate and opposite to the drawing direction.

<Rinse process>
(Preparation of rinse solution)
The rinse solution was prepared by adding dropwise a 48% NaOH aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) to 500 ml of pure water while stirring to obtain a predetermined pH.
Then, 0.1% by weight of the total amount of sofazoline LAO (manufactured by Kawaken Fine Chemical Co., Ltd.) was added and stirred for 30 minutes to prepare a rinse solution.
[Rinse process]
Each rinse solution prepared on each plate material engraved by the above method is dropped with a dropper (about 2 ml) so that the plate surface gets evenly wet, and left to stand for 1 minute. The brush was rubbed in parallel with the plate at the load and the number of brush rubs shown in Table 2. Thereafter, the plate surface was washed with running water, the water on the plate surface was removed, and air-dried for about 1 hour.

(Evaluation)
<Resistance removal>
The surface of the rinsed plate was observed with a × 100 microscope VHX-1000 (manufactured by Keyence Corporation), the residue on the plate was observed, and the number of rubbing without any residue was evaluated. The smaller the number of rubbing, the better the debris removal and the shorter the debris removal time.

<Productivity>
The area that can be engraved in 1 hour was calculated from the engraving time when raster engraving was performed so that the engraving depth was 0.5 mm at a solid portion of 1 cm square under the condition of 2,400 DPI. The larger the value, the better the recording sensitivity and the better the productivity.

<Sculpture edge shape>
The concave line and the edge part of the convex line produced under the engraving conditions were visually observed with a microscope VHX-1000 (manufactured by Keyence Corporation) at a magnification of 300 times.
○: Edge is sharp ×: Edge is rounded and smooth

DESCRIPTION OF SYMBOLS 11 Plate making apparatus 20 Light source unit 21 Semiconductor laser 22 Optical fiber 23 Adapter board 24 Light source board 25 SC type optical connector 27 LD driver board 29 Wiring member 30 Exposure head 32 Collimator lens 33 Opening member 34 Imaging lens 40 Exposure head moving part 41 Ball screw 42 Rail 43 Sub-scanning motor 44 Stage 46, 47 Bearing 50 Drum 51 Main scanning motor 52 Axis 55 Chuck member 60 Focus position changing mechanism 61 Motor 62 Ball screw 70 Optical fiber 71 Optical fiber end 80 Engraving (dent)
81 Engraving residue 90 Intermittent feed mechanism 92 Exposure range 280 Light emitting part 282 V-shaped groove 300 Optical fiber array part 301 Optical fiber end group 302 Base 500 Fiber array unit light sources 501, 502, 503, 504 Optical fiber array unit F Relief printing plate precursor FA exposure surface

Claims (6)

Preparing a relief printing plate precursor having a crosslinked relief forming layer; and
Including a engraving step of laser engraving the relief printing plate precursor,
The crosslinked relief forming layer is obtained by crosslinking a relief forming layer containing (Component A) a binder polymer and (Component B) a photothermal conversion agent,
The content of the component B is 0.1% by weight or more based on the total solid content of the relief forming layer,
The engraving step is a step of engraving using an exposure head in which at least two semiconductor lasers having a wavelength of 700 nm to 1,300 nm are arranged.
In the engraving process, gas is blown at a wind speed of 10 m / s or more against the laser irradiation part, and
The method of making a relief printing plate, wherein the gas blowing angle is 0 ° or more and less than 90 ° when an angle parallel to the plate surface and opposite to the drawing direction is 0 °. The plate-making method of the relief printing plate of Claim 1 whose crosslinking density of the said crosslinked relief formation layer is 10 * 10 < ² > mol / mL or more.   The relief printing plate according to claim 1 or 2, wherein the component B is carbon black having an oil absorption of less than 150 mL / 100 g and / or a pigment and / or dye having peak light absorption at 800 nm to 1,200 nm. Plate making method.   The plate-making method of the relief printing plate of any one of Claims 1-3 which contains the said component B 0.1weight% or more and 15 weight% or less with respect to the total solid of a relief forming layer.   The plate making method of the relief printing plate of any one of Claims 1-4 whose said semiconductor laser is a semiconductor laser with a fiber.   The relief printing plate obtained by the method of any one of Claims 1-5.

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