JP3475591B2 - Printing plate material and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing plate material that can be engraved with laser light and a method for producing the printing plate material.

[0002]

2. Description of the Related Art Conventionally, a plate material for laser engraving printing in which polyethylene is mixed with carbon black to form a sheet is known. However, high-energy laser light is required to form irregularities on the surface. Therefore, a printing plate material capable of forming irregularities on the surface using a low energy laser beam has not been put into practical use at present.

On the other hand, a recording material containing nitrocellulose is also known in order to increase the sensitivity, but its strength as a printing plate material is not sufficient. For example, Japanese Patent Publication No. Sho 51-35144
The publication discloses that a photosensitive material containing nitrocellulose and carbon black is coated on a support, and a laser beam is irradiated from the back surface of the support coated with a photosensitive layer to form an image. This prior art document discloses an example of printing with the ink on the photosensitive layer. However, the film strength of this photosensitive layer is insufficient and is not practical as a printing plate material.

JP-B-51-6569 discloses a photosensitive material containing nitrocellulose as a self-oxidizing binder, carbon black as particles for absorbing laser energy, and melamine resin as a cross-linking agent (cross-linking agent). An imaged printed board having a coating formed thereon is disclosed. In this document, alkyd resin, methylmethacrylate resin, butyral resin as a binder resin,
An example in which an epoxy resin and a novolac resin are used in combination is also described. However, in the light-sensitive material described in this document, a light-sensitive layer applied to a support and a polyvinyl alcohol layer applied to an aluminum plate for surface hydrophilization treatment are brought into close contact with each other, and laser light is irradiated from the back surface of the support. Then, the image corresponding to the irradiated portion is transferred to an aluminum plate and used as a lithographic printing plate, and is not a plate material for printing by directly transferring printing ink to the photosensitive layer. further,
Since the film strength of the photosensitive layer formed of the photosensitive material is insufficient, it is difficult to directly use it as a printing plate material.

Special table 4 corresponding to WO90 / 12342
No. 506709 discloses a sensitizer that absorbs infrared rays,
An imaging material using a composition containing polyurethane as a degradable binder is disclosed. However, the material described in this document is a kind of thermal transfer color imaging material that forms a reversal image by transferring the remaining binder and dye to the receptor sheet by decomposing part of the decomposable binder by heat. Therefore, it is not a plate material for printing by directly transferring the printing ink to the photosensitive layer.

When a pit is formed in the photosensitive layer containing nitrocellulose, a light absorber and a heat-melting component (such as a binder) by irradiation with laser light, part of the melt-sensitive component is decomposed and evaporated, and the rest is melted. However, the edge of the pit is raised. Therefore, when printing is performed by applying a printing ink to the surface of the photosensitive layer, the quality of printed matter such as printing accuracy is impaired (for example, Japanese Patent Publication No. 1-291717, Japanese Patent Publication No. 57-163597, Japanese Patent Publication No. No. 6569).

Further, in order to improve the durability and printing durability of the photosensitive layer, it seems useful to use an elastomer having rubber elasticity. However, when an elastomer having a glass transition temperature lower than the operating temperature is used and the sheet-shaped printing plate materials are stacked, the photosensitive layer may be blocked on another support. On the other hand, if the content of nitrocellulose is increased and the glass transition temperature is higher than the use temperature, blocking of the photosensitive layer can be reduced, but it no longer has the properties as an elastomer, and the scratch resistance is reduced. The layers cannot be effectively protected.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to print even when ink is directly transferred to the surface of a photosensitive layer on which pits have been formed by a laser beam, and the surface where the edge of the pit is smooth. An object of the present invention is to provide a printing plate material capable of forming a photosensitive layer having high smoothness and preventing blocking, and a manufacturing method thereof. Another object of the present invention is to
It can be engraved with low laser energy,
An object of the present invention is to provide a printing plate material having excellent durability and printing durability and a method for producing the same. Still another object of the present invention is to provide a printing plate material having a photosensitive layer which is excellent in scratch resistance and blocking resistance even if it contains an elastomer, and a method for producing the same. Another object of the present invention is to provide a printing plate material having high sensitivity (thermal decomposition) to laser light and capable of forming a photosensitive layer having a sharp pit shape, and a method for producing the same.

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the surface of the photosensitive layer is transparent to laser light and is removable from the photosensitive layer. It was found that when a surface layer is formed, blocking can be prevented by the surface layer, and when the surface layer is removed after forming a pit by irradiating laser light from the surface layer side, it is possible to suppress the rise of the peripheral portion of the pit. The present invention has been completed.

That is, in the printing plate material of the present invention, a photosensitive layer and a light-transmitting surface layer are sequentially laminated on a support. In this printing plate material, the photosensitive layer can form pits by the laser beam irradiated from the surface layer side, and the surface layer can be removed from the photosensitive layer by peeling or elution. Such a surface layer may be formed of a transparent or translucent film which can be peeled from the photosensitive layer.
Further, the surface layer may be formed of a solvent that does not corrode the photosensitive layer, for example, a water-soluble polymer or an alcohol-soluble polymer that can be dissolved in water or alcohol. The photosensitive layer is formed of various photosensitive compositions capable of forming pits by irradiation with laser light, such as nitrocellulose, a light absorber and a poly ( vinyl acetate ).
It is composed of a binder made of urethane elastomer .
This photosensitive layer may further contain a plasticizer. Further, an antistatic layer or a slipping layer may be formed on the surface of the photosensitive layer. The printing plate material of the present invention can be produced by sequentially forming, on a support, a photosensitive layer that can be engraved by a laser beam and a light-transmitting surface layer that can be removed from the photosensitive layer.
Further, the printing plate material on which an image corresponding to the print pattern is formed is irradiated with laser light from the light-transmitting surface layer side to form pits in the photosensitive layer, and the surface layer is removed from the photosensitive layer. Can be manufactured. In addition, in the present specification, the term “film” is used to include a sheet unless otherwise specified.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The printing plate material of the present invention comprises a photosensitive layer formed on a support and capable of forming pits by laser light, and a light-transmitting surface layer formed on the photosensitive layer. The photosensitive layer can be formed of various materials having high sensitivity to laser light and not impairing the accuracy of pits, for example, a photosensitive composition containing nitrocellulose, a light absorber and a binder.
The type of nitrocellulose contained in the photosensitive layer is not particularly limited as long as it can be thermally decomposed, and RS (regular solubl
e) type, SS (spirit soluble) type and AS (a
lcohol soluble) type. . The nitrogen content of the nitrocellulose is usually 10 to 14%.
%, Preferably 11 to 12.5%, more preferably 11.5 to 12.2%. The degree of polymerization of nitrocellulose can be selected within a wide range of, for example, about 10 to 1500. The preferable degree of polymerization of nitrocellulose is, for example, about 10 to 900, particularly about 15 to 150. Preferred nitrocellulose includes nitrocellulose having a solution viscosity according to JIS K6703 "industrial nitrocellulose" (viscosity display method by Hercules Powder Co., Ltd.) of 20 to 1/10 seconds, preferably 10 to 1/8 seconds.
As the nitrocellulose, nitrocellulose having a solution viscosity of 5 to 1/8 second, particularly 1 to 1/8 second is often used. As the nitrocellulose for forming the photosensitive layer, RS type nitrocellulose soluble in an ester such as ethyl acetate, a ketone such as methyl ethyl ketone and methyl isobutyl ketone, and an ether such as cellosolve (for example, a nitrogen content of 11. In most cases, 7 to 12.2% nitrocellulose) is used. Two or more kinds of nitrocellulose may be used in combination, if necessary.

The amount of nitrocellulose used can be selected within a range that does not reduce the sensitivity of the photosensitive layer. For example, it is 5 to 300 parts by weight, preferably 20 to 250 parts by weight, and more preferably 50 parts by weight per 100 parts by weight of the binder. ˜200 parts by weight, and often 40 to 200 parts by weight.

The light absorber contains an absorber that efficiently absorbs laser energy, for example, a dye such as a black dye, a carbon material and the like. A preferred carbon material includes carbon black, and this carbon black is AST as long as the dispersion stability of the composition is stable.
In addition to the classification according to M, any one can be used regardless of the application (for example, for color, for rubber, for dry cell, etc.). Carbon black includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black and the like. In addition,
A black colorant such as carbon black can be used as a color chip or a color paste in which a dispersant is used as necessary in order to facilitate dispersion, and the colorant is previously dispersed in nitrocellulose or a binder. Chips and pastes are easily available as commercial products.

The amount of the light absorber used can be selected within a range that does not reduce the sensitivity of the photosensitive layer. For example, it is 0.5 to 50 parts by weight, preferably 2.5 parts by weight with respect to 100 parts by weight of the binder.
To 40 parts by weight, more preferably 10 to 30 parts by weight, and often 5 to 50 parts by weight.

The binder is not particularly limited as long as it does not impair the sensitivity to laser light, durability and printing durability, and various resins such as acrylic resin and styrene resin can be used. The binder is insoluble in water and alcohol (particularly methanol and ethanol), and is often soluble in organic solvents such as esters such as ethyl acetate, ketones, ethers and hydrocarbons. Preferred binders include polyesters and polyurethanes (especially polyurethane elastomers). When the photosensitive layer is formed by combining the binder with the nitrocellulose and the light absorber as described above, irregularities (pits) can be formed in the photosensitive layer even with low laser energy, and the film strength and scratch resistance of the photosensitive layer are strong. There is an advantage to say. In addition, even when the printing ink is transferred directly to the photosensitive layer having irregularities and printed, high scratch resistance is exhibited, and durability and printing durability are high.

The above polyester includes polycarboxylic acid or its acid anhydride or lower alkyl ester (hereinafter,
Various polyesters obtained by a condensation reaction between a polyhydric carboxylic acid component) and a polyhydric alcohol component can be used. Further, in the polymerization of the polyester, an oxycarboxylic acid may be used instead of the component or together with the component. A preferred polyester is JP-A-7-4.
It is disclosed in Japanese Patent No. 0674. That is, as the polyvalent carboxylic acid component, for example, aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid and their acid anhydrides; succinic acid, glutaric acid, adipic acid, Examples thereof include saturated or unsaturated aliphatic carboxylic acids such as azelaic acid, sebacic acid, maleic acid and fumaric acid, and acid anhydrides thereof.
The oxycarboxylic acid includes, for example, β-oxypropionic acid and β-oxybutyric acid.

Examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, trimethylene glycol, butanediol, pentanediol,
Alkylene glycols such as 1,6-hexanediol and neopentyl glycol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol and polytetramethylene glycol; trimethylolpropane, trimethylolethane, penta Aliphatic polyhydric alcohols such as erythritol; Cyclohexanediol, alicyclic polyhydric alcohols such as hydrogenated bisphenol A; 2,2-bis (4-dihydroxyethylphenyl)
Examples thereof include adducts of bisphenol A and alkylene oxide such as propane and 2,2-bis (4-dihydroxypropylphenyl) propane. The molecular weight of the polyester is, for example, about 1000 to 100,000, preferably about 2,000 to 50,000, and usually, a polyester soluble in an organic solvent is often used.

Preferred polyesters include polyesters having an aromatic ring, for example, linear aromatic polyesters having excellent solvent resistance and abrasion resistance. Such polyester includes polyethylene terephthalate ethylene glycol and / or a part of terephthalic acid and other diols (eg, polyoxyalkylene glycol such as triethylene glycol) and / or dicarboxylic acids (isophthalic acid, phthalic acid, etc.). ) Substituted modified polyester is included. It is also advantageous to use a polyester elastomer in order to enhance durability, printing durability and scratch resistance of the photosensitive layer.

The type of polyurethane is not particularly limited as long as it does not impair the sensitivity to laser light and printing durability.
Preferred polyurethanes include polyurethane elastomers such as polyols such as polyester polyols, polyether polyols, acrylic polyols, polyisocyanates, and optionally polyhydric alcohols and / or
Alternatively, various polyurethane elastomers obtained by using a chain extender such as polyamine are included. The above polyols can be used alone or as a mixture, but in many cases, at least a polyester polyol is included. As the polyester polyol, a linear polyol is preferable because it is rich in elasticity, but since the viscosity increases as the molecular weight increases, a slightly branched polyol may be used.

The components of the polyester polyol include a polycarboxylic acid component (especially dicarboxylic acid) and a polyhydric alcohol component (especially diol). Examples of the polyvalent carboxylic acid component and the polyhydric alcohol component include the same components as described in the section of the polyester. As the polyvalent carboxylic acid component for forming the polyester polyol, an aliphatic carboxylic acid (for example, a saturated aliphatic dicarboxylic acid such as adipic acid, azelaic acid, sebacic acid) is often used, and as the polyhydric alcohol component, In many cases, at least aliphatic dihydric alcohol or polyoxyalkylene glycol is used. The molecular weight of the polyester polyol is, for example, 500 to 5000, preferably 700 to 3000, and more preferably 1000 to 200.
It is about 0.

As the polyisocyanate, for example,
Aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate and 1,5-naphthalene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6- Examples thereof include aliphatic diisocyanates such as hexamethylene diisocyanate and 1,10-decamethylene diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate. These polyisocyanates may be used either individually or in combination of two or more.

As the chain extender, the same polyhydric alcohols as described above (for example, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-Pentanediol, 1,6-hexanediol, neopentyl glycol and other diols, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol and other polyols) can be used. Further, as the chain extender, a polyamine, for example,
(Poly) alkylene polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine and propylenediamine; alkanolamines such as monoethanolamine, diethanolamine and triethanolamine can also be used. Preferred chain extenders are polyhydric alcohols.

The polyurethane elastomer includes a prepolymer having an isocyanate group formed by a reaction between a polyester polyol, a polyisocyanate and a polyhydric alcohol, or a reaction between the polyol such as the polyester polyol and a polyisocyanate, and a chain extender (polyether). Often formed by reaction with (hydric alcohols, etc.). As the polyurethane elastomer, any elastomer can be used as long as the sensitivity to laser light and the strength of the photosensitive layer are not impaired. A preferred polyurethane elastomer has an elongation of 400% or more (for example, 400 to 1000).
%), Preferably 500% or more (for example, 500 to
Polyurethane elastomer of about 900%) is included. The glass transition temperature Tg of the polyurethane elastomer is, for example, -10 ° C or lower (for example, -10 ° C to-).
50 ° C.), preferably −15 ° C. or lower (eg, −1)
5 ° C. to −45 ° C.), and more preferably −20 ° C. or lower (eg, −20 ° C. to −40 ° C.).

The glass transition temperature of the photosensitive layer is, for example, -25 ° C to 40 ° C, preferably -15 ° C to 35 ° C.
More preferably, it is about -10 ° C to 30 ° C. Depending on the ratio of the nitrocellulose and the binder (especially, an elastomer such as a polyester elastomer or a polyurethane elastomer), stacking sheet-shaped printing plate materials may cause blocking of the photosensitive layer. The glass transition temperature of the photosensitive layer is 25 ° C. or higher (for example, about 25 to 40 ° C.), preferably about 25 to 35 ° C., in order to improve the durability and scratch resistance while preventing the blocking of the photosensitive layer. Is preferred. The glass transition temperature of the photosensitive layer can be controlled by the ratio of nitrocellulose and a binder (for example, polyurethane elastomer).

The glass transition temperature of the elastomer is
Usually, it is lower than room temperature, and for example, it is about -15 ° C to -50 ° C for polyurethane elastomer. When a photosensitive layer is formed using such an elastomer and nitrocellulose, the glass transition temperature of nitrocellulose is high, so that the glass transition temperature of the photosensitive layer rises as the amount of nitrocellulose increases, and the photosensitive layer is exposed to laser light. The sensitivity of the layer can be increased. However, if the content of nitrocellulose is increased, the scratch resistance and durability of the photosensitive layer may decrease. In such cases,
The addition of a plasticizer is useful. That is, even if the proportion of nitrocellulose is increased, the addition of the plasticizer can suppress an increase in the glass transition temperature of the photosensitive layer and maintain high durability and scratch resistance. Furthermore, as the nitrocellulose content increases, the sensitivity to laser light (pyrolysis) can be increased. The plasticizer is effectively added to the composition constituting the photosensitive layer having a glass transition temperature of 0 to 40 ° C., preferably about 10 to 30 ° C.

The plasticizer is not particularly limited as long as it can plasticize the photosensitive layer (for example, a photosensitive layer composed of nitrocellulose, a light absorber and a binder). For example, camphor or its derivative, phthalic acid ester (dimethyl ester). Phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, dioctyl phthalate, di2-ethylhexyl phthalate, etc.), phosphoric acid ester (eg, triphenyl phosphate, tricresyl phosphate, etc.), adipic acid ester (eg, di (2 -Ethylhexyl) adipate, etc.), sebacic acid ester (eg, dibutyl sebacate, etc.) and the like. As the plasticizer, a plasticizer having a plasticizing effect on at least nitrocellulose is often used. These plasticizers can be used alone or in combination of two or more.

The amount of the plasticizer used depends on the type of binder such as nitrocellulose or polyurethane elastomer and the glass transition temperature of the photosensitive layer. For example, the composition of the photosensitive layer (for example, nitrocellulose, light absorber and Total amount of binder) 0.1 to 30 per 100 parts by weight
The amount can be selected from the range of about 1 to 20 parts by weight, more preferably about 2 to 15 parts by weight.

The photosensitive layer may contain a crosslinking agent, if necessary. As the cross-linking agent, for example, melamine resin,
Examples thereof include amino resins such as benzoguanamine resin and urea resin; organic peroxides such as benzoyl peroxide, di-t-butyl peroxide, and ethyl methyl ketone peroxide. The photosensitive layer may further contain various additives, for example, antioxidants such as antioxidants and ultraviolet absorbers, crosslinking accelerators, crosslinking catalysts, flame retardants, fillers, colorants, leveling agents, etc. It may be contained.

The shape of the support may be a drum shape, a film shape or a sheet shape as long as it can be printed.
The material of the support is not particularly limited, but when the support is a film or sheet, a polymer film such as a polyethylene terephthalate film is often used. The surface of the support may be surface-treated or an undercoat layer may be formed in order to enhance the adhesion to the photosensitive layer.

The thickness of the photosensitive layer formed on the support can be selected within a range that does not impair the durability of the photosensitive layer.
It is about 1 to 100 μm, preferably about 10 to 50 μm, and often about 15 to 30 μm.

When a pit is formed by irradiating the photosensitive layer formed on the support with laser light, the peripheral edge of the pit rises and the surface smoothness of the photosensitive layer is liable to deteriorate. Also, the glass transition temperature of the photosensitive layer should be lower than the operating temperature (for example, about 2
When rubber elasticity is exhibited at room temperature (0 ° C. or lower), scratch resistance may be improved, but a blocking phenomenon may occur. That is, the operating temperature of the printing plate is usually 20
Since it is a room temperature of about -30 ° C, printing plate materials having the above-mentioned photosensitive layer are stacked in a sheet shape, for example,
Blocking occurs when stored at a temperature of about 50 to 80 ° C. Further, in order to improve the scratch resistance, it may be considered to add an organic polymer to increase the hardness of the photosensitive layer, but there is a limit to increase the hardness of the photosensitive layer with an organic polymer or the like. Therefore, in the present invention, a light-transmitting surface layer capable of transmitting laser light is formed on the surface of the photosensitive layer. That is, when a light-transmissive surface layer that can be removed from the photosensitive layer is formed on the surface of the photosensitive layer, pits are formed in the photosensitive layer by irradiating laser light from the surface layer side to remove the surface layer from the photosensitive layer. Then, the surface smoothness can be improved even in the peripheral portion of the pit. Further, a residue (for example, a component which does not disappear due to the irradiation of the laser beam and remains due to melting or the like) that remains after the irradiation of the laser beam can be removed together with the removal of the surface layer. Therefore, when used as a printing plate material on which an image of pits is formed, it is possible to obtain a high-quality printed matter by using a plate material having a sharp pit shape and having a highly accurate plate surface. Also, due to the surface layer,
Even if the glass transition temperature of the photosensitive layer is low, blocking of the photosensitive layer can be reliably prevented.

The surface layer is permeable to laser light and does not significantly attenuate the energy of the laser light.
As long as it is non-adhesive and has blocking resistance, it is not limited to being transparent and may be semi-transparent. The surface layer that can be removed from the photosensitive layer can be formed of, for example, a transparent or translucent film that can be peeled from the photosensitive layer, a layer that can be eluted in a solvent that does not corrode the photosensitive layer (eluting surface layer), and the like.

As the film which can be peeled from the photosensitive layer, various films having a low affinity for the photosensitive layer, for example, olefin-containing polymers (for example, olefin-based polymers such as polyethylene, polypropylene and ethylene-propylene copolymer) are used. , Ethylene-vinyl acetate copolymers, olefin-vinyl monomer copolymers such as ethylene- (meth) acrylic acid ester copolymers or derivatives thereof, polyalkylene terephthalates (for example, polyethylene terephthalate), polyamides (for example,
Nylon 6, Nylon 66, Nylon 11, Nylon 1
2), a hydrophilic film (for example, polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, a co-extruded film composed of a polyethylene layer and a polyvinyl alcohol layer), and the like. The film may be a monolayer film or a composite film. Further, the film may be a uniaxially stretched film, a biaxially stretched film, or a microporous film such as a uniaxially stretched microporous film. Preferred films include a film having high releasability from the photosensitive layer, for example, an olefin-containing polymer film, a hydrophilic polymer film, and a film in which at least the contact surface with the photosensitive layer is composed of such a polymer layer. .

Of these films, the contact surface with the photosensitive layer may be subjected to a release treatment (for example, a treatment with a release agent such as silicone oil, wax, fatty acid amide). Such a film can be selected depending on the components of the photosensitive layer. For example, when the photosensitive layer contains polyester or polyurethane, the film forming the surface layer is preferably formed of an olefin-containing polymer. The thickness of the film layer is not particularly limited as long as it does not impair the releasability from the photosensitive layer, and is, for example, 1 to 30 μm, preferably 5
It is often about 25 μm.

The elutable surface layer can be formed of various solvent-soluble polymers as long as it is dissolved or dissolved in a solvent that does not attack the photosensitive layer and does not cause blocking of the photosensitive layer, depending on the components of the photosensitive layer. In many cases, the component is insoluble or slightly soluble in water or alcohol. for that reason,
Preferred solvent-soluble polymers include water-soluble polymers or alcohol-soluble polymers.

As the water-soluble polymer or alcohol-soluble polymer, various polymers soluble in water and / or alcohol, for example, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl ether (for example, polyvinyl methyl ether) are used. , Polyvinyl isobutyl ether, etc.), water-soluble or alcohol-soluble acrylic resin (for example, (meth) acrylic acid ester- (meth) acrylic acid copolymer), water-soluble or alcohol-soluble styrene resin (for example, styrene-maleic anhydride) Acid copolymer, (meth) acrylic acid ester-styrene- (meth) acrylic acid copolymer, etc.), polyalkylene oxide, cellulose ether (for example, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, Droxyethyl cellulose, hydroxypropyl cellulose, etc.), water-soluble or alcohol-soluble cellulose esters (eg low-substituted cellulose ester, nitrocellulose etc.), water-soluble or alcohol-soluble polysaccharides (eg sodium alginate, gum arabic etc.) Can be mentioned. These water-soluble or alcohol-soluble polymers can be used alone or in admixture of two or more. As the alcohol-soluble polymer, a polymer soluble in methanol or ethanol is often used in order to suppress erosion or elution of the components of the photosensitive layer. When nitrocellulose is used as the alcohol-soluble polymer, SS type nitrocellulose (for example, nitrocellulose having a nitrogen content of 10.7 to 11.2%) or AS type nitrocellulose soluble in alcohol, particularly methanol or ethanol. Cellulose (for example, nitrocellulose having a nitrogen content of 11.2 to 11.7%) is often used. The thickness of the elution surface layer can be selected within a range that does not impair the elution property.
1 to 10 μm, preferably 0.5 to 7 μm (for example, 1
.About.5 .mu.m).

When such a leaching surface layer is formed, the surface layer can be dissolved and removed using a solvent that does not attack the photosensitive layer. Therefore, even if the photosensitive layer is easily blocked, a blocking resistant surface layer is formed. It is possible to reliably prevent the photosensitive layer from blocking during storage and the like. Further, since the transparent or semi-transparent surface layer suppresses the attenuation of the laser light and the recording sensitivity is not likely to decrease, the pits can be easily removed after the pits are accurately formed on the photosensitive layer. Furthermore, when the surface layer is formed of a composition that can be dissolved in the solvent of the printing ink (for example, the vehicle of the printing ink), the surface layer can be naturally dissolved and removed by the solvent of the printing ink during the process of printing or test printing. In particular, when the surface layer is formed using the same or similar composition (coating liquid) as the printing ink, particularly the composition containing the vehicle of the printing ink, even if the surface layer is dissolved in the printing ink, the surface for the printing ink Since the quantity ratio of the layers is small, the composition of the printing ink hardly changes and the printability of the printing ink is not adversely affected.

The printing plate material of the present invention may be housed in a jacket and used for convenience of carrying. In that case, in order to make it easy to take in and out of the jacket,
It is also possible to form an antistatic layer or a slipping layer on the light-transmitting surface layer. In the printing plate material having such a structure, not the photosensitive layer but the surface layer not involved in recording by laser light may be treated with an antistatic agent or a lubricant, so that the antistatic agent or the lubricant can be freely selected from an extremely wide range. The advantage is that you can choose. As the antistatic agent, for example,
Anionic surfactants such as alkyl sulfates, alkylaryl sulfonic acids or salts thereof, alkyl phosphates, cationic surfactants such as quaternary ammonium salts and imidazoline compounds, amphoteric activators such as alkyl betaines, nonionic surfactants, etc. Can be mentioned. As a lubricant,
Examples thereof include wax, fatty acid amide, saturated higher fatty acid, silicone oil and the like. The thickness of the antistatic layer or the slipping layer is not particularly limited and is, for example, about 0.1 to 5 μm in many cases.

The printing plate material can be produced by forming a photosensitive layer which can be engraved with laser light on the support and forming a light-transmitting surface layer removable from the photosensitive layer on the photosensitive layer. . The photosensitive layer can be formed by applying a coating liquid containing the components of the photosensitive layer (for example, nitrocellulose, a light absorber and a binder resin) to the support. The coating liquid can be prepared by using an organic solvent and mixing and dispersing the components of the photosensitive layer using a conventional mixer or disperser. Examples of the organic solvent include alcohols such as ethanol and isopropanol; aliphatic hydrocarbons such as hexane and octane; alicyclic hydrocarbons such as cyclohexane; benzene, toluene,
Aromatic hydrocarbons such as xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether and tetrahydrofuran; and mixed solvents thereof. Are exemplified. The light-transmitting surface layer can be formed by a conventional method depending on the type of the surface layer, for example, laminating a film or applying a coating solution containing the components of the elutable surface layer.

The printing plate material thus obtained is irradiated with laser light from the light-transmitting surface layer side in accordance with a predetermined pattern to remove the surface layer from the photosensitive layer.
It is used as a plate material having irregularities (pits) in the photosensitive layer and is subjected to a printing process using printing ink. The surface layer can be removed by peeling the film, or elution or dissolution with a solvent (for example, water or alcohol) as described above.

When the surface layer is used as an anti-blocking layer, the surface layer is removed prior to the irradiation of laser light and the photosensitive layer is irradiated with laser light to form a pit image, which is used as a plate material. It may be subjected to a printing process. Further, the laser light may be irradiated from the support side if the support is transparent, but the irradiation from the surface layer side is
It is useful for improving the accuracy of pits and the surface smoothness of the photosensitive layer. Examples of the laser light source include Ar laser, He-Ne laser, He-Cd laser, carbon dioxide laser, YGA laser, and semiconductor laser. The printing plate material of the present invention forms a concavo-convex pattern by irradiation with laser light, and can be used as a printing plate for various types of printing such as gravure printing and flexographic printing.

[0042]

In the printing plate material of the present invention, since the photosensitive layer and the light-transmitting surface layer are sequentially formed on the support, even if the laser beam is irradiated, the surface of the pit edge portion is smooth. A photosensitive layer having high smoothness can be formed, and blocking resistance can be greatly improved. Further, it is possible to print by directly transferring the ink to the surface of the photosensitive layer on which the pits are formed, and it is possible to obtain a high-quality printed matter due to the high dimensional accuracy of the pits. Further, when the photosensitive layer is composed of nitrocellulose, a light absorber and a binder, it has high sensitivity (thermal decomposability) to a laser beam, and pits having a sharp shape can be accurately formed even with low laser energy. In particular, when polyester or polyurethane is used as the binder, durability and printing durability can be improved, and when an elastomer is used as the binder, scratch resistance can be enhanced and blocking can be prevented by the surface layer. Furthermore, by containing a plasticizer in the photosensitive layer, it is possible to enhance the sensitivity to laser light and form pits having a sharp shape while maintaining high scratch resistance and blocking resistance. According to the method of the present invention, a printing plate material having the above-mentioned excellent properties can be easily produced by a simple operation of forming a photosensitive layer and a surface layer. Further, in the method of the present invention,
By irradiating a laser beam from the surface layer side to remove the surface layer, pits having high shape and dimensional accuracy can be formed in the photosensitive layer, and a high quality printed matter can be obtained.

[0043]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples. Example 1 Nitrocellulose RS1 / 4 (Daicel Chemical Industry Co., Ltd.)
Made of isopropanol wet cotton with a solid content of 70% by weight) 7.7
21.1 parts by weight, paste containing carbon black (color paste ANP-C-903 black, carbon black content 12% by weight, nitrocellulose H1 / 2 content 18% by weight, manufactured by Toyo Ink Co., Ltd.) 21.1 parts by weight, polyurethane elastomer (Nippon Polyurethane Industry Co., Ltd., N
2304, solid content 35% by weight, elongation 750%, glass transition temperature -23 ° C) 40.1 parts by weight, and methyl ethyl ketone 32.2 parts by weight were added to ceramic beads (diameter 3
mm) was mixed and dispersed in a paint shaker for 30 minutes to obtain a coating liquid. The obtained coating liquid was applied to a polyethylene terephthalate film (thickness 1
88 μm) to a thickness of 25 μm after drying,
It was dried at 110 ° C. for 2 minutes to form a photosensitive layer. On this photosensitive layer, a coextruded film composed of a polyethylene layer and an ethylene-vinyl acetate copolymer layer (thickness: 50-60 μm)
The ethylene-vinyl acetate copolymer layer side of m) was laminated to prepare a printing plate material. The surface of the polyethylene layer of the coextruded film is antistatic-treated.

Then, the plate material of Example 1 was fixed on a rotary drum and rotated at a speed of 3 rpm, and a semiconductor laser (He
A pulsed light of -Cd laser, wavelength 441 nm, 5 mW) was irradiated for 50 msec to form pits in the photosensitive layer of the plate material. Then, the coextrusion film was peeled from the photosensitive layer, and the depth and shape of the pits were examined with a scanning laser microscope (LASE
When measured by RTEC, 1LM21), the pit depth was 4.25 μm, and the sensitivity of the photosensitive layer to laser light was high. Therefore, it was possible to form irregularities (pits) by laser light even at high speed. In addition, the pit edges did not rise, the pit edges were sharp, and the surface was smooth.

Example 2 Nitrocellulose RS1 / 4 (Daicel Chemical Industry Co., Ltd.)
Made of isopropanol wet cotton with a solid content of 70% by weight) 7.7
24.6 parts by weight of paste containing carbon black (manufactured by Toyo Ink Co., Ltd., color paste ANP-C-903 black), polyester (manufactured by Toyobo Co., Ltd.,
Byron 20SS, solid content 30% by weight 43.3 parts by weight, cross-linking agent (manufactured by Dainippon Ink and Chemicals, Melamine resin, Super Beckamine L-105-60, solid content 60)
% By weight) 5.4 parts by weight, acid catalyst (BYK, BYK CATA
LYST450, solid content of about 40% by weight), and 18.7 parts by weight of methyl ethyl ketone were mixed and dispersed to obtain a coating liquid. A printing plate material was obtained in the same manner as in Example 1 except that the obtained coating liquid was used.

Then, laser light irradiation was carried out in the same manner as in Example 1, and the pit depth and shape were observed. The pit depth was 3.98 μm, and the sensitivity of the photosensitive layer to the laser light was high. . In addition, the pit edges did not rise, the pit edges were sharp, and the surface was smooth.

Comparative Example 1 Without laminating the coextruded film on the photosensitive layer,
A printing plate material was produced in the same manner as in Example 1. When the photosensitive layer of the obtained plate material was irradiated with laser light in the same manner as in Example 1 and the depth and shape of the pits were observed, the pit depth was 4.50 μm. Although it was slightly deeper, the pit edge was slightly raised and the pit edge was unclear.

Comparative Example 2 Without laminating the coextruded film on the photosensitive layer,
A printing plate material was prepared in the same manner as in Example 2. When the photosensitive layer of the obtained plate material was irradiated with laser light in the same manner as in Example 2 and the pit depth and shape were observed, the pit depth was 4.13 μm. Although it was slightly deeper, the pit edge was slightly raised and the pit edge was unclear.

Example 3 Nitrocellulose RS1 / 4 (manufactured by Daicel Chemical Industries, Ltd.)
Made of isopropanol wet cotton with a solid content of 70% by weight) 6.6
21.1 parts by weight of a paste containing carbon black (manufactured by Toyo Ink Co., Ltd., color paste ANP-C-903 black), 40.1 parts by weight of polyurethane elastomer (N2304 manufactured by Nippon Polyurethane Industry Co., Ltd.), And 32.2 parts by weight of methyl ethyl ketone were mixed and dispersed to obtain a coating liquid. The obtained coating liquid was applied to a polyethylene terephthalate film (thickness 1
88 μm) to a thickness of 25 μm after drying,
It was dried at 110 ° C. for 2 minutes to form a photosensitive layer. Nitrocellulose SS1 / 4 (manufactured by Daicel Chemical Industries, Ltd., isopropanol wet cotton with a solid content of 70% by weight) 3 parts by weight was dissolved in 100 parts by weight of ethyl alcohol, and the film-shaped plate material having the photosensitive layer was added to the solution. A printing plate material was prepared by immersing and drying at 100 ° C. for 1 minute. The thickness of the surface layer covering the photosensitive layer was about 10 μm.

Then, the plate material was fixed on a rotary drum and rotated at a speed of 3 rpm, and pulsed light of a semiconductor laser (He-Cd laser, wavelength 441 nm, output 5 mW) was 50 m.
It was irradiated for sec to form pits in the photosensitive layer of the plate material. When the pit depth was measured with a scanning laser microscope (1LM21, manufactured by LASERTEC), the pit depth was 5.90 μm, and the sensitivity of the photosensitive layer to laser light was high. Therefore, it was possible to form irregularities (pits) by laser light even at high speed.

Further, the plate material on which the pits were formed was immersed in ethanol to remove the transparent surface layer, and then the shape of the pits was observed. As a result, the edges of the pits were sharp and the surface was smooth. Furthermore, a taper abrasion machine (made by Yasuda Seiki,
Taver type application tester, wear wheel CS-1
After abrading the photosensitive layer using 0, a load of 500 g), a gloss meter (manufactured by Moritex Co., Ltd., PRANGE gloss meter RB3,
The scratch resistance of the photosensitive layer was evaluated by measuring the decrease in glossiness with respect to the number of abrasions using an incident angle and a reflection angle = 60 °. In addition, the glossiness at a predetermined wear number (20 times, 50 times, and 100 times) was obtained by setting the gloss degree at the wear number of 0 as 100%. As a result, the glossiness was 70.0% when the number of wear was 20 and the glossiness was 60 when the number of wear was 50.
5%, the gloss is 53.0% at 100 abrasions,
The photosensitive layer showed good scratch resistance.

The obtained plate material and the polyethylene terephthalate film were each set to a predetermined size (5c).
m × 5 cm), the surface layer and the film are overlapped and sandwiched between glass plates having the same area, and a load of 1 kg is applied to 70
A blocking test was performed at ° C. As a result, no blocking was observed even after 2 hours.

Example 4 After a photosensitive layer was formed in the same manner as in Example 3, 7 parts by weight of a water-soluble acrylic-styrene copolymer resin, 1.7 parts by weight of dimethylethanolamine, and 4.5 parts by weight of n-propanol were used. , 0.4 parts by weight of polyethylene wax and 74.2 of water
Immerse the film plate material in the solution of 1 part by weight, and
A printing plate material was produced by drying for a minute. Then, when the depth of the pit formed by the irradiation of the laser beam was measured in the same manner as in Example 3, the pit depth was 5.60 μm, and the sensitivity of the photosensitive layer to the laser beam was high.

Further, the plate material having the pits was immersed in ethanol to remove the transparent surface layer, and then the shape of the pits was observed. As a result, the edges of the pits were sharp and the surface was smooth. Furthermore, the scratch resistance of the photosensitive layer was evaluated in the same manner as in Example 3. Assuming that the glossiness at 0 wear is 100%, the glossiness at 71 wear is 71.
The photosensitive layer showed good scratch resistance, with a gloss of 62.3% when the abrasion number was 50, and a gloss of 53.2% when the abrasion was 100. Further, a blocking test between the surface layer and the film was conducted in the same manner as in Example 3,
No blocking was observed after 2 hours.

Comparative Example 3 A photosensitive layer was formed in the same manner as in Example 3 to prepare a printing plate material. The photosensitive layer of the obtained plate material was irradiated with laser light in the same manner as in Example 3 and the pit depth was measured.
It was 51 μm. The edge of the pit was slightly raised, and the edge of the pit was unclear. Furthermore, after thoroughly cleaning the surface of the photosensitive layer with ethanol, the scratch resistance of the photosensitive layer was evaluated in the same manner as in Example 3. The number of abrasions was 20 when the glossiness when the number of abrasions was 0 was 100%. 70.4% glossiness, 50 wear count glossiness 61.0
%, The glossiness was 54.8% when the number of abrasions was 100, and the photosensitive layer exhibited good scratch resistance. Further, when a blocking test was performed on the surface layer and the film in the same manner as in Example 3, blocking occurred after 1 hour.

Examples 5 and 6 Instead of the polyurethane elastomer of Example 1, a polyurethane elastomer (manufactured by Nippon Polyurethane Industry Co., Ltd.,
N3022, solid content 35% by weight, elongation rate 800%, glass transition temperature −38 ° C.), and using the nitrocellulose of Example 1, the paste containing carbon black and methyl ethyl ketone, the photosensitive layer having the composition ratio shown in Table 1. Was formed. Further, the film was laminated in the same manner as in Example 1 to obtain a printing plate material.

Examples 7 and 8 Instead of the polyurethane elastomer of Example 1, a polyurethane elastomer (manufactured by Nippon Polyurethane Industry Co., Ltd.,
N3107, solid content 40% by weight, elongation 850%, glass transition temperature −33 ° C.), and using the nitrocellulose of Example 1, the paste containing carbon black and methyl ethyl ketone, the photosensitive layer having the composition ratio shown in Table 1. Was formed. Further, the film was laminated in the same manner as in Example 1 to obtain a printing plate material.

Examples 9 and 10 Instead of the polyurethane elastomer of Example 1, a polyurethane elastomer (manufactured by Nippon Polyurethane Industry Co., Ltd.,
N3118, solid content 40% by weight, elongation rate 800%, glass transition temperature -38 ° C), and using the nitrocellulose of Example 1, the paste containing carbon black and methyl ethyl ketone, the photosensitive layer having the composition ratio shown in Table 1. Was formed. Further, the film was laminated in the same manner as in Example 1 to obtain a printing plate material.

Example 11 Instead of the polyurethane elastomer of Example 1, a polyurethane elastomer (manufactured by Nippon Polyurethane Industry Co., Ltd.,
N3110, solid content 25% by weight, elongation rate 700%, glass transition temperature -15 ° C.) and using the nitrocellulose of Example 1, the paste containing carbon black and methyl ethyl ketone, and the photosensitive layer having the composition ratio shown in Table 1. Was formed, and a transparent surface layer was formed on this photosensitive layer in the same manner as in Example 3 to obtain a printing plate material.

Example 12 Nitrocellulose RS 1/4 (manufactured by Daicel Chemical Industries, Ltd.)
Made of isopropanol wet cotton with a solid content of 70% by weight) 5.1
22.9 parts by weight of a paste containing parts by weight, carbon black (color paste ANP-C-903 black LV, manufactured by Toyo Ink Co., Ltd., carbon black content 10% by weight, nitrocellulose H1 / 2 content 15% by weight), polyurethane Elastomer (Nippon Polyurethane Industry Co., Ltd.,
N2304, solid content 35% by weight, elongation 750%, glass transition temperature -23 ° C) 26.4 parts by weight, camphor 1.4 parts by weight and methyl ethyl ketone 44.3 parts by weight are mixed and dispersed for 1 hour with a paint shaker. Other than Example 1
A printing plate material having a surface film layer that was peelable from the photosensitive layer was prepared in the same manner as in.

Examples 13 and 14 Example 12 except that the proportions of the components of Example 12 are varied.
In the same manner as in, a printing plate material having a photosensitive layer having a composition ratio shown in Table 1 and a surface film layer was prepared.

Then, after irradiating with laser light in the same manner as in Example 1, the surface film layer was peeled off or the surface layer was removed by elution, and the depth and shape of the pits formed in the photosensitive layer were observed. However, the results shown in Table 1 were obtained.

[0063]

[Table 1] As shown in Table 1, the pits were deep and showed high sensitivity to laser light, and pits with sharp edges were formed. When the blocking properties of the printing plate materials of the respective examples were examined in the same manner as in Example 3, no blocking was observed in any printing plate material even after 2 hours.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-50-158405 (JP, A) European patent application publication 580393 (EP, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41N 1/12 B41C 1/05 G03F 7/00 505

Claims (9)

(57) [Claims] To 1. A on a support, a photosensitive layer and a light permeable surface layer are sequentially stacked with respect to the laser beam, the photosensitive layer, nitrocellulose, light absorber, polyurethane
A printing plate material composed of a binder composed of a tan elastomer . Wherein the photosensitive layer pits can be formed by laser beams radiated from the surface layer side is formed on the support,
The printing plate material according to claim 1, wherein the surface layer removable from the photosensitive layer is formed on the photosensitive layer. 3. The printing plate material according to claim 1, wherein the surface layer is formed of a transparent or translucent film which can be peeled from the photosensitive layer. 4. The olefin-containing polymer as the film.
The printing plate material according to claim 3, which is a film. 5. The printing plate material according to claim 1, wherein the surface layer can be dissolved in a solvent that does not corrode the photosensitive layer. 6. A photosensitive layer, with respect to 100 parts by weight of the binder, wherein comprising 5 to 300 parts by weight nitrocellulose, carbon black 0.5 to 50 parts by weight of a light absorber
The printing plate material according to Item 1 . 7. The photosensitive layer further contains a plasticizer, and the proportion of the plasticizer is 0.1 to 100 parts by weight based on 100 parts by weight of the total amount of nitrocellulose, the light absorber and the binder constituting the photosensitive layer.
The printing plate material according to claim 1, which is 30 parts by weight. 8. A photosensitive layer capable of being engraved with laser light and a light transmissive surface layer removable from the photosensitive layer are sequentially formed on a support, and the laser light is irradiated from the light transmissive surface layer side. The above exposure
Forming pits in the layer, and forming the light-transmitting surface layer on the photosensitive layer.
A method of manufacturing a printing plate material for removing from a plate. 9. The photosensitive layer comprises nitrocellulose and light absorption.
Body, binder made of polyurethane elastomer
The method for producing a printing plate material according to claim 8, which is formed.