JP2003035955A - Photosensitive printing original plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive CTP flexographic printing original plate that suppresses the creasing and cracking of an IR ablation layer and is excellent in image reproducibility on the presupposition that the original plate is attached to a cylindrical drum without difficulty. SOLUTION: The photosensitive printing original plate has at least (A) a support, (B) a photosensitive resin layer and (C) an IR ablation layer, and (C) the IR ablation layer contains a polyol and/or an amine compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive printing original plate used for producing a flexographic printing plate by a computer plate making technique, which is free from wrinkles and cracking and has excellent image reproducibility. It relates to the original plate for printing.

[0002]

2. Description of the Related Art Recently, in the field of flexographic printing, computer plate making technology (CTP technology) also known as digital image forming technology has become extremely popular. In CTP technology, the photomasks (also called photomasks or negative films) traditionally used to cover non-polymerizable areas of a photosensitive printing plate are
It has been replaced by a mask that is formed and integrated in the printing plate. There are two possible ways to obtain such an integrated mask, but there are two technologies on the market. That is, a mask is printed with an ink jet printer on the photosensitive printing plate, or a layer (I that is substantially opaque to actinic radiation) (I) that is substantially opaque to actinic radiation is formed on the photosensitive layer.
R ablation layer or infrared ablation layer),
An image is formed on such a mask with an IR laser. Such an IR ablation layer usually contains carbon black as an IR absorbing material. This IR
The photopolymerizable printing plate having an ablation layer is, for example, E
It is disclosed in P-A654150 or EP-A767407. By irradiating with an IR laser, the black layer is lost in that part, and the underlying photosensitive layer is exposed.
The laser device is directly connected to the layout computer system. Using this technique, the image is generally formed directly on the plate and exposed to actinic radiation in the next step.

The CTP technique not only avoids making a separate photomask, but also provides much higher resolution. For a detailed discussion of the superiority of CTP technology over conventional technology, see, for example, "Deutsher Drucker, Nr. 21/3.
6.99, w12-w16 ".

An important step in the method of making a flexographic printing plate using a photosensitive printing plate having an IR ablation layer is the step of irradiating the element with an IR laser. I
The R ablation layer must meet several requirements for good results. For economic reasons, I
The time to irradiate the R ablation layer should be as short as possible. Therefore, the sensitivity to IR irradiation needs to be as high as possible. Furthermore, for image formation,
In the current state of the art, laser devices with rotating drums are used. The photosensitive flexographic plate is attached to a cylindrical drum, and the laser is irradiated while rotating the drum at 2000 rpm. For this reason, when the photosensitive flexographic printing plate is wound around the drum, if the plate is bent, cracking occurs in the IR ablation layer, or conversely, when the plate is flattened when removed from the drum, wrinkles appear on the surface of the IR ablation layer. If it occurs, it will be a hindrance to the irradiation of actinic rays in the next step. Therefore, the IR ablation layer must be elastic to prevent the IR ablation layer from wrinkling or tearing when flexing the flexographic printing plate.

EP-A 654 150 discloses a photosensitive flexographic printing plate having an IR ablation layer. The IR ablation layer comprises an IR absorbing material. In addition, it optionally contains polymeric binders and various other ingredients (eg, pigment dispersants, surfactants, plasticizers,
Or coating aid). However, there is no suggestion in the above publication on how to improve the flexibility for mounting on a cylindrical drum without the above problems.

EP-A767407 discloses an IR containing a flexible film forming binder and carbon black.
Photosensitive printing plates having an ablation layer are disclosed. As binders, polyamides (eg Macromelt®) or polyvinyl alcohol / polyethylene / glycol graft polymers (eg Mowiol®) are mentioned. Such binders are impractical as they require a pre-treatment step to develop only IR ablation, and there is no description of how to improve flexibility for mounting on a cylindrical drum.

Japanese Unexamined Patent Publication (Kokai) No. 2-113254 discloses a technique in which a polyvinyl alcohol is blended with a plasticizer as a wrinkle preventive agent for a non-tackiness preventing layer for a conventional flexographic printing plate. However, in the technique described in the above publication, the IR ablation layer provided for applying the CTP technique is an IR ablation layer.
The composition and function are different in that the absorbent is included. Therefore CT
It does not satisfy the puck technology's unique cracking prevention and wrinkle prevention functions when it is attached to or removed from the cylindrical drum.

[0008]

SUMMARY OF THE INVENTION The present invention is based on the assumption that it can be mounted on a cylindrical drum without any problems.
Suppresses wrinkles and cracking in the ablation layer,
An object of the present invention is to provide a photosensitive CTP flexographic printing original plate having excellent image reproducibility.

[0009]

Means for Solving the Problems The inventors of the present invention have earnestly studied, studied, and studied the photosensitive printing plate in order to solve the above problems, and as a result, finally completed the present invention. That is, the present invention is a photosensitive printing original plate having at least (A) a support, (B) a photosensitive resin layer, and (C) an IR ablation layer, wherein the (C) IR ablation layer is a polyhydric alcohol and / or Alternatively, a photosensitive printing original plate containing an amine compound. (C) The photosensitive printing original plate as described above, wherein the IR ablation layer contains at least one binder, at least one IR absorbing material, and at least one polyvinyl alcohol as the binder. (C) The photosensitive printing original plate as described in any one of the above, wherein the IR absorbing material in the IR ablation layer is carbon black.

As the support (A) suitable for the photosensitive printing original plate of the present invention, a material which is flexible but has excellent dimensional stability is preferably used. For example, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene. Examples thereof include terephthalate film and polycarbonate, which have sufficiently high viscoelasticity that can be used as a support material having excellent dimensional stability. The thickness of the film used here is 50 to 250 μ.
m, preferably 100 to 200 μm is desirable from the viewpoint of mechanical properties, shape stabilization, handleability during plate making. If necessary, a commonly used adhesive may be provided to improve the adhesion between the support and the photosensitive resin layer.

The photosensitive resin layer (B) used in the photosensitive printing original plate of the present invention may be applied to any known photosensitive layer, and is a photosensitive resin layer constituting the photosensitive printing original plate of the present invention. It is not particularly limited, and contains one kind of elastomer binder, at least one kind of polymerizable compound (hereinafter also referred to as a crosslinking agent), and at least one kind of photoinitiator or a photoinitiator composition. In the present invention,
A photosensitive resin layer that can be developed with water or an aqueous medium is preferable,
Specifically, JP-A-60-212451 and JP-A-2
-175702, JP-A-4-3162, JP-A-2-305805, JP-A-3-228060.
Examples thereof include photosensitive resin compositions described in JP-A No. 10-339951 and the like.

The elastomer binder may be a single polymer or a polymer mixture. Further, it may be a hydrophobic polymer, a hydrophilic polymer, or a mixture of both. Examples of suitable binders include butadiene rubber, isoprene rubber, and 1,2-
Polybutadiene, styrene-butadiene rubber, chloroprene rubber, nitrile-butadiene rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, butadiene- (meth) acrylic acid Hydrophobic polymers such as ester copolymer, acrylonitrile- (meth) acrylic acid ester copolymer, epichlorohydrin rubber, chlorinated polyethylene, silicone rubber, urethane rubber, and -COOH, -COOM (M is monovalent, divalent, or trivalent) metal ions or substituted or unsubstituted ammonium _{ion), - OH, -NH 2,} -SO 3 H, a hydrophilic polymer having a hydrophilic group such as a phosphoric acid ester group, for example,
Polymer of (meth) acrylic acid or a salt thereof, (meth)
Copolymers of acrylic acid or its salts with alkyl (meth) acrylates, copolymers of (meth) acrylic acid or its salts with styrene, copolymers of (meth) acrylic acid or its salts with vinyl acetate, A copolymer of (meth) acrylic acid or a salt thereof and acrylonitrile, polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, hydroxyethyl cellulose, polyethylene oxide, polyethyleneimine, polyurethane having a -COOM group, polyurea urethane having a -COOM group,- Examples thereof include polyamic acid having a COOM group and salts or derivatives thereof.

The polymerizable compound preferably used is a conventional polymerizable ethylenic mono- or polyunsaturated organic compound which can be used for producing a polymerizable printing plate and is compatible with the elastomer binder. Examples of such monomers include styrene, vinyltoluene, t-butylstyrene, α-methylstyrene, acrylonitrile,
(Meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n
-Butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) ) Acrylate, n-tridecyl (meth) acrylate, stearyl (meth) acrylate, ethylene glycol mono (meth) acrylate,
Propylene glycol mono (meth) acrylate, diethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol monomethyl ether mono (meth) acrylate, Polypropylene glycol monomethyl ether mono (meth) acrylate, polyethylene glycol monoethyl ether mono (meth) acrylate, polypropylene glycol monoethyl ether mono (meth) acrylate, n-butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2- Phenoxypropyl (meth) acrylate, cyclohexyl (meth)
Acrylate, tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) acrylate, allyl (meth) acrylate, benzyl (meth) acrylate, tribromophenyl (meth) acrylate, 2,3-dichloropropyl (meth) acrylate, 3-chloro- 2-
Hydroxypropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, acrylamide, N, N-dimethylacrylamide , N, N-diethylacrylamide, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate,
Propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol (meth) acrylate, neopentyl glycol Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,12-dodecanediol di ( (Meth) acrylate, 1,14-tetradecanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerine Di (meth) acrylate, glycerol allyloxydi (meth) acrylate, trimethylolethanedi (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate , Dicyclopentyldimethylene di (meth) acrylate, dicyclopentadecane di (meth) acrylate, tricyclodecanediyldimethyldi (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl phthalate, divinyl Benzene, polyurethane (meth) acrylate, polyester (meth) acrylate, oligobutadiene (meth) acrylate, oligoisoprene (meth) acrylate , And the like oligopropylene (meth) acrylate.

Examples of photoinitiators include benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ethers, benzyl alkyl ketals, anthraquinones, thioxanthones and the like. Specifically, benzophenone, chlorobenzophenone, benzoin, acetophenone, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, benzyl diethyl ketal, benzyl diisopropyl ketal, anthraquinone, 2-ethyl anthraquinone Examples thereof include 2-methylanthraquinone, 2-allylanthraquinone, 2-chloroanthraquinone, thioxanthone, and 2-chlorothioxanthone. The (B) photosensitive resin layer in the invention may further contain an additive, for example, a plasticizer, a thermal polymerization inhibitor, a dye or an antioxidant.

(B) By appropriately selecting the components of the photosensitive resin layer, the person skilled in the art can dissolve in a water-soluble developing solution, a semi-water-soluble developing solution or an organic solvent-based developing solution according to a desired solubility characteristic. Alternatively, a dispersed photopolymerizable layer can be produced.

The main components of the photosensitive printing original plate of the present invention are (B) a novel (C) provided on the photosensitive resin layer.
An IR ablation layer, and the present invention is characterized in that the layer contains a polyhydric alcohol and / or an amine compound. The IR ablation layer is substantially impermeable to actinic radiation (ie, opaque to actinic radiation), and generally has an optical density to actinic radiation of greater than 2.5, preferably greater than 3.5. Is. Optical densities are obtained through the imaged IR ablation layer at the wavelength or range of wavelengths of actinic radiation used for total exposure of the photosensitive composition.

(C) The polymeric binder in the IR ablation layer can be effectively removed by the heat generated by the IR absorbing material when the IR ablation layer is exposed to IR laser irradiation. The term "heat-flammable" means that the binder decomposes, depolymerizes, or evaporates without the preceding melting stage. For this reason,
Each pixel of the image has a very steep edge, resulting in high resolution.

Any type of polymer binder can be used within the scope of the present invention as long as it is a binder satisfying the above-mentioned requirements. However, the polymer binder of the aqueous development type photosensitive resin composition can be used. In some cases, water-soluble polymers can be preferably used. Specific examples include polyvinyl alcohol and its derivatives, cellulosics, water-soluble butyral, and compounds having a hydroxyl group in the molecule, but at least one of oxygen-blocking properties, film-forming properties, temperature and humidity resistance, and coatability is selected. It preferably contains polyvinyl alcohol, polyacrylic acid, polyethylene oxide and the like.
Above all, the degree of polymerization is 500 to 4000, preferably 1000.
~ 3000, saponification degree 70% or more, preferably 80-9
9%, more preferably 80-90% polyvinyl alcohol and modified polyvinyl alcohol are desirable.

The IR ablation layer in the present invention is
In addition to the binder, a polyhydric alcohol and / or an amine compound is contained as another component. Specifically, low molecular weight alkylene glycols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, propylene glycol, pentamethylene glycol, hexylene glycol and hexamethylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene. Glycol, polyethylene glycol # 20
0, low molecular weight polyalkylene glycols such as polyethylene glycol # 300, polyethylene glycol # 400, polyethylene glycol # 600, butanediols such as 2,3 butanediol and 1,3 butanediol, glycerin, sorbitol, pentaerythritol, tri Examples include polyhydric alcohols such as trihydric or higher alcohols such as methylolpropane, ethanolamines such as monoethanolamine, diethanolamine and triethanolamine, and amine compounds such as N-methylpyrrolidone, cyclohexylamine and urea. Again 2
Mixtures of one or more can also be used.

In the present invention, the amount of polyhydric alcohol and / or amine compound in the IR ablation layer is
1 to 4 relative to the total amount of all components of the IR ablation layer
0% by weight, especially 15 to 35% by weight is preferred. If the blending amount exceeds 40% by weight, blocking of the dry film occurs,
It is not preferable because it hinders coating productivity. In the present invention, by compounding the compound, an IR ablation layer having elastic properties capable of bending and stretching without wrinkles or cracking can be obtained, but the reason is not clear.

In addition, the IR ablation layer comprises at least one IR absorbing material, which is 750-200.
It has a strong absorption in the range of 00 nm and is uniformly dispersed in the layer. Suitable IR absorbing materials include IR absorbing dyes (eg, phthalocyanine and substituted phthalocyanine derivatives,
Cyanine dye, merocyanine dye and polymethine dye)
Alternatively, a dark-colored inorganic pigment (eg, carbon black, graphite, iron oxide or chromium oxide) can be used. In the present invention, it is preferable to use carbon black. Carbon black ensures that the IR ablation layer becomes opaque to actinic radiation, thereby making absolutely unnecessary the addition of other UV-absorbing dyes. It is desirable to use a small particle size for maximum color strength. In particular, it is desirable to use a brand of fine carbon black with an average particle size of less than 60 nm. Examples of suitable brands include PrintexR U (Printex (registered trademark) U), PrintexR L6, Spezialschwarz 4 (Spectier Schwarz (registered trademark) 4) or Spezialschwarz 250.
(Made by Degussa) and BONJET CW-1 (made by Orient Chemical).

Generally, the amount of the IR absorbing material incorporated in the IR ablation layer is 1 to 60% by weight, and further 10 to 50% by weight based on the total amount of all components of the IR ablation layer.
Weight% is preferable, and 25 to 50 weight% is particularly preferable.
If it is less than 1% by weight, the optical density of the IR ablation layer with respect to actinic rays will be less than 2.0, causing fog in the relief image. If it exceeds 60% by weight, I
It is not preferable because the mechanical strength of the R ablation layer becomes insufficient and the developer is contaminated or deteriorated in the subsequent development process.

The (C) IR ablation layer can also contain additional components and additives, if desired. Examples of such components include polymeric binders, pigment dispersants, fillers, surfactants or coating aids which need not be heat-flammable. Such additives can be selected by those skilled in the art according to the desired properties for the layer, provided that they do not adversely affect the imageability of the IR ablation layer. UV as an additive
It is also possible to use absorbing materials or dyes which absorb in the UV. The use of UV-absorbing materials is also advantageous with carbon black as an IR absorber, while other I
It should be avoided with R absorber. Although the number thereof is not limited, the amount of such an additive is preferably 20% by weight or less, particularly preferably 10% by weight or less, based on the total amount of all components of the IR ablation layer.

(C) The component of the IR ablation layer is I
It is preferred that the R ablation layer be selected so that it dissolves or at least swells in the developing solution of the photosensitive resin layer.
However, the present invention is not limited to this aspect.

(C) It is advantageous to cover the photosensitive printing plate with a peelable flexible cover sheet on the IR ablation layer. Suitable peelable flexible cover sheets include, for example, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film. However, such a protective cover sheet is not absolutely necessary.

It is also advantageous, but not essential, to use at least one of the additional binders as a release-modifying polymer which facilitates the removal of the coversheet without damaging the IR ablation layer.

The photosensitive printing original plate of the present invention may have one or more layers between the above layers, if desired. Examples of such layers are known in the art and are adhesive layers, especially those between the support and the photosensitive layer,
Mention may be made of an intermediate layer between the light-sensitive layer and the IR ablation layer for preventing the diffusion of monomers or other small molecules from one layer to another layer, or a non-stick layer.

Next, the method for producing the photosensitive printing original plate of the present invention will be specifically described. First, all the components of the IR ablation layer are dissolved in a suitable solvent, or when a pigment such as carbon black is used, a dispersion liquid with the pigment and other components in a suitable solvent is prepared. In the latter case,
The use of dispersed carbon black is recommended. Such a solution or dispersion is applied directly on the photosensitive layer and then the solvent is evaporated. Alternatively, such a solution or dispersion is coated on a support (eg PET sheet) and then the solvent is evaporated. The coated support is then laminated under pressure and / or heating with the photosensitive layer of the printing plate such that the photosensitive layer is adjacent to the IR ablation layer. In addition,
The IR ablation layer support functions as a protective film for the surface of the photosensitive printing original plate.

Next, the method for producing a flexographic printing plate from the photosensitive printing original plate of the present invention also includes the step of removing the protective film from the photosensitive printing plate, if any. After that, the IR ablation layer is irradiated with an IR laser for an image to form a mask on the photosensitive resin layer. Examples of suitable IR lasers are ND / YAG lasers (1064 nm) or diode lasers (eg 830).
nm). Suitable laser systems for computer engraving techniques are commercially available, for example the diode laser system CDI Spark (Barco Graphics), which comprises a rotating cylindrical drum and an IR ablation layer mounted thereon. And a photosensitive flexographic printing plate. The image information is transferred directly from the layout computer to the laser device.

After writing the mask on the IR ablation layer, the photosensitive flexographic printing plate is blanket exposed to actinic radiation through the mask. This is advantageously done directly on the laser cylinder. Alternatively, the plate is removed from the laser device and illuminated with a conventional flat illumination unit. The actinic ray is 150 to 500 nm, especially 300 to 400 n.
It is cured by irradiation with ultraviolet rays having a wavelength of m. As the light source, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon lamp, a zirconium lamp, a carbon arc lamp, a fluorescent lamp for ultraviolet rays, etc. can be used. During the irradiation step, the photosensitive layer polymerizes in the areas exposed in the previous ablation step, while no polymerization occurs in the IR ablation layer areas which are still covered by the IR ablation layer that is opaque to the irradiation light. EP
As described in JP-A-767407, the irradiation of actinic radiation can be carried out by removing oxygen in a conventional vacuum frame, but it is advantageous to carry out irradiation in the presence of atmospheric oxygen.

The irradiated plate is then developed to give a flexographic printing plate. The developing step can be carried out in a conventional developing unit. When the photosensitive resin layer is a water-developing type, the developer may be only water, but contains water as a main component and an alkaline compound such as sodium hydroxide or sodium carbonate, a surfactant, a water-soluble organic solvent or the like. You may. As the surfactant, sodium alkylnaphthalene sulfonate, sodium alkylbenzene sulfonate, etc. are most suitable, and in addition, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants are used. it can. The developing solution is preferably used at 25 to 50 ° C. Further, depending on the properties of the plate, water, an organic solvent, or a mixture of these solvents can be used. During development, the unpolymerized areas of the photosensitive layer and the residual portions of the IR ablation layer are removed. It is also possible to first remove the IR ablation layer with one solvent or solvent mixture and then develop the photosensitive layer with another developer. After the development step, the printing plate obtained is dried. Typical conditions for a plate with a PET base film are 15 to 6 at 60 to 70 ° C.
0 minutes. Printing plate with PET base film is 65
Even at a temperature higher than 0 ° C, it can be dried without loss of dimensional stability, and the drying time can be shortened. Further post-treatment operations can be performed.

The photosensitive printing original plate of the present invention exhibits excellent flexibility. It can be bent and stretched without wrinkling or cracking in the IR ablation layer. This means that the plate can be mounted and dismounted on the laser drum without causing problems. Moreover, this plate is much more sensitive to IR laser irradiation than conventional printing plates.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION As one embodiment for obtaining the photosensitive printing original plate of the present invention, for example, a polyester film having a thickness of 125 μm is prepared, and the ablation layer coating solution described above is stored at 105 ° C. for 3 minutes. Is coated and dried to prepare a cover film having a thin layer having an ablation layer thickness of about 4 μm. Next, a support in which a polyester adhesive is applied to a polyethylene terephthalate film having a thickness of 125 μm is prepared, and the support is disclosed in JP-A-10-33995.
A photosensitive resin layer having a thickness of 1.7 mm is obtained by calendering a photosensitive resin layer composed of the photosensitive resin composition described in JP-A No. 1-centered with both materials to obtain a T2 size (610 mm ×
762 mm) to obtain a printing original plate. Next, digital data of an evaluation pattern is recorded on the ablation layer using this original plate, and exposed, cured and developed to obtain a printing plate, which is printed on a coated paper with a printing ink of a water-based ink. With these operations, the photosensitive printing original plate of the present invention is free from mistakes in the cover peeling operation during plate making as compared with the conventional one, and the printing property of the finished printing plate is good in ink transfer and image reproducibility.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" means "parts by weight".
The evaluation method in the examples is based on the method described below. 1) Evaluation of wrinkles and cracking: When a 1.7 mm-thick plate was mounted on a drum having a diameter of 200 mm, the IR ablation layer surface was cracked and the IR ablation layer surface was wrinkled after desorption. I observed. 2) Preparation of printing plate: exposure machine (A & V) having a lamp (manufactured by Philips) with an illuminance of 95 to 105 w / m 2.
Back exposure 55 seconds, front exposure 30 minutes, developer 3% sodium alkylnaphthalene sulfonate at 40 ° C. 7
It was developed in minutes to make a printing plate.

Reference Example 1 <Production of Hydrophilic Polymer> 119.0 parts of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.), 62.0 parts of dimethylolpropionic acid (Fujii Yoshitsusho), polytetramethylene glycol (G -850, Hodogaya Chemical Co., Ltd.) 29.0 parts and dilaurylate di-n-butyltin 5.0 parts dissolved in tetrahydrofuran 300 parts, this solution was placed in a 1 liter flask equipped with a stirrer, and stirring was continued. While 65 ℃
The reaction was continued for 2 hours. In a container other than this, 184.0 parts of acrylonitrile-butadiene oligomer having an amino group at the terminal (Hycar ATBN 1300 × 16, manufactured by Ube Industries, Ltd.) was added to tetrahydrofuran 27
The solution dissolved in 0 part was added to the above 1 liter flask at room temperature with stirring. Tetrahydrofuran was distilled off from this polymer solution under reduced pressure and dried under reduced pressure to obtain a polymer having a number average molecular weight of 6700. Next, 100 parts of this polymer was dissolved in 100 parts of methyl ethyl ketone, and to this was added a solution prepared by dissolving 4.8 parts of lithium hydroxide in 100 parts of methanol, and further stirred for 30 minutes to obtain a hydrophilic polymer.

Reference Example 2 <Production of Photosensitive Resin> 12 parts of the hydrophilic polymer obtained in Reference Example 1 and a nitrile-butadiene rubber (35% acrylonitrile) as a hydrophobic polymer (A) (JSR N230SH, Japan Synthetic Rubber ( 42 parts, butadiene rubber as a hydrophobic polymer (B) (JSR BR02L, Japan Synthetic Rubber Co., Ltd.)
15 parts, oligobutadiene acrylate (P-B-A, manufactured by Kyoeisha Chemical Co., Ltd.) as a non-gaseous ethylenically unsaturated compound, 29 parts, benzyl dimethyl ketal as a photopolymerization initiator, and a thermal polymerization inhibitor. 0.5 parts of hydroquinone monomethyl ether was kneaded together with 40 parts of toluene and 10 parts of water at 105 ° C. using a heating kneader, and then toluene and water were distilled off under reduced pressure. T2
This operation was repeated several times to obtain the original plate, and thus a photosensitive resin was obtained.

Reference Example 3 <Preparation of IR Ablation Layer (I)> To 829 parts of pure water was added 25 parts of Gohsenol GH-23 (saponification degree: 87-88%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.),
The mixture was stirred at 90 ° C for 1 hour. Next, after cooling to room temperature, 28 parts of carbon black BONJET CW-1 was added to this aqueous solution,
20 parts of polyethylene glycol # 600 and SE-27
0 [Sanyo Kasei Co., Ltd. polyethylene sorbitol 85% pure content] 10 parts and Epan 740 (Daiichi Kogyo Seiyaku Co., Ltd.)
0.06 part) was slowly added with stirring, and the mixture was further stirred for 30 minutes. Next, this solution is 100μ at a speed of 6m / min.
m thick chemical matte film (manufactured by Toyo Cross Co., Ltd.)
TC-5002) was coated with a reverse roll and dried at 105 ° C. for 3 minutes with a dryer having a wind speed of 0.5 m / min. The IR ablation layer thus obtained had a thickness of 4 μm.
Was the thickness of.

Reference Example 4 <Preparation of IR Ablation Layer (II)> A cover film having an IR ablation layer (II) was prepared in the same manner as in Reference Example 3 except that polyethylene glycol # 600 was not added. did.

Reference Example 5 <IR ablation layer (III)
Preparation of Reference Example 3 except that 15 parts of triethanolamine was added in place of polyethylene glycol # 600 in Reference Example 3
A cover film having an IR ablation layer (III) was prepared in the same manner as in.

Reference Example 6 <Preparation of IR Ablation Layer (IV)> The IR ablation layer (IV) was prepared in the same manner as in Reference Example 3 except that the amount of polyethylene glycol # 600 was changed to 10 parts. ) Was prepared.

Example 1 <Preparation Method of Photosensitive Printing Master Plate> A photosensitive resin obtained in Reference Example 2 was mainly used by using a support prepared by coating a polyester adhesive on a polyethylene terephthalate film having a thickness of 125 μm. 80 ℃
It is sandwiched between the calender rolls that have been heated to
A photosensitive resin laminate having a thickness of m was prepared, and this was cut into a T2 size (610 mm × 762 mm) to prepare a printing original plate. The weight of this printing original plate was 855 g, and the packing operation was easy. The IR ablation layer (I) produced in Reference Example 3 and the above-mentioned photosensitive resin layer were laminated by the above-mentioned method to obtain the photosensitive printing original plate of the invention. The surface of the IR ablation layer was evaluated for wrinkles and cracking, but no wrinkles or cracking was observed and the IR ablation layer was good. When the relief after plate making was printed with a water-based ink, halftone dots of 150 lines and 2% were reproduced and the printability was good.

Comparative Example 1 A photosensitive printing original plate was obtained in the same manner as in Example 1 except that the IR ablation layer (II) obtained in Reference Example 4 was used as the IR ablation layer. It was When the wrinkles and cracking on the surface of the IR ablation layer were evaluated, fine cracking frequently occurred on the surface of the IR ablation layer when mounted on a drum in a platemaking environment of 24 ° C./33% RH. Moreover, wrinkles occurred when returning to a flat state after desorption, and wrinkles did not recover even if left for a while. Next, when exposure and development were carried out in the same manner as in Example 1, wrinkles remained on the surface of the photocured image, and ink transfer unevenness was also observed on the printed matter.

Example 2 A photosensitive printing original plate was obtained in the same manner as in Example 1 except that the IR ablation layer (III) obtained in Reference Example 5 was used as the IR ablation layer. It was The mat film, which is the cover film of the obtained photosensitive printing original plate, was peeled off and mounted on the drum, but cracking did not occur in the plate making environment of 33% RH to 71% RH. In addition, no wrinkles were observed even when it was returned to a flat shape. Upon further exposure, development and printing, good printed matter was obtained.

Example 3 A photosensitive printing original plate was obtained in the same manner as in Example 1 except that the IR ablation layer (IV) obtained in Reference Example 6 was used as the IR ablation layer. It was The obtained photosensitive printing original plate was subjected to relative humidity of 33% RH.
The surface of the IR ablation layer was observed by mounting and demounting on a drum in a plate making environment of ˜71% RH, but cracking and wrinkles were not observed. Further, when exposure, development and printing were carried out in the same manner as in Example 1, a good printed matter was obtained.

[0045]

As described above, the photosensitive printing plate precursor of the present invention having such a constitution is surprisingly obtained by combining a heat-flammable polymer binder with a specific plasticizer.
An IR ablation layer exhibits excellent sensitivity to IR irradiation, resulting in a high imaging speed, and at the same time a high flexibility, a photosensitive flexographic printing plate is obtained, which allows the plate to be protected from wrinkles in the IR ablation layer. It can be attached to the cylindrical drum of the laser device without cracking, can prevent wrinkles and cracking, and can obtain a CTP flexographic plate excellent in image reproducibility, which is a great contribution to the industry.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Imahashi             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. F-term (reference) 2H025 AA02 AB03 AD01 BC13 BC42                       BH01 CA00 DA03 DA11 DA31                       FA06                 2H096 AA06 BA05 BA06 EA02 EA04                       EA13

Claims (3)

[Claims] 1. A photosensitive printing original plate having at least (A) a support, (B) a photosensitive resin layer, and (C) an IR ablation layer, wherein the (C) IR ablation layer is a polyhydric alcohol and / or Alternatively, a photosensitive printing original plate containing an amine compound. 2. The photosensitive printing original plate according to claim 1, wherein the (C) IR ablation layer contains at least one binder, at least one IR absorbing material, and at least one polyvinyl alcohol as the binder. 3. (C) IR in the IR ablation layer
The photosensitive printing original plate according to claim 1, wherein the absorbing material is carbon black.