JPH09138514A - Electrophotographic planographic printing plate material for laser light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planographic printing plate material having high sensitivity to semiconductor laser light of about 635nm wavelength. SOLUTION: A middle layer and a photoconductive layer based on a mixture of photoconductive pigment with an electric insulating adhesive are successively formed on one face of a water resistant substrate to obtain the objective planographic printing plate material. The photoconductive layer contains at least one kind of dye compd. represented by formula I and tetrabromophenol blue and has sensitivity to semiconductor laser light of 635nm wavelength. In the formula I, R1 is -CH2 COO, -C2 H4 COO or -C3 H6 COO and R2 is-CH2 COOH, -C2 H4 COOH or -C3 H6 COOH.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrophotographic lithographic printing plate material for laser light. More specifically, the present invention relates to an electrophotographic lithographic printing plate material spectrally sensitized to a semiconductor laser beam having an oscillation wavelength of 635 nm.

[0002]

2. Description of the Related Art In recent years, with the development of small-size offset printing presses and the development of automatic printing presses, the mainstream of light printing is shifting to offset printing. Many researches and developments have been made on such offset printing plate materials, and various materials have been put to practical use. Among these materials, electrophotographic planographic printing plate materials having a photoconductive layer containing zinc oxide as a main component are inexpensive, and occupy the mainstream of light printing plate materials because the plate making process is simple. I have. To produce an electrophotographic lithographic printing plate, usually, corona charging, exposure, according to the desired pattern using a plate making machine for the printing plate material,
A method is widely used in which a development and fixing process is performed to form a visible image of a desired pattern on the photoconductive layer.

In the developing step, a dry developing method using a mixture of toner and a carrier such as iron powder, and a wet developing method using a developing solution obtained by dispersing the toner in an organic solvent such as a high boiling point petroleum solvent. There is.

When a plate is produced using the above-mentioned wet development method,
There are advantages such as good reproducibility of halftone image formation, excellent resolution, short time required for plate making, and no need to correct the formed image. For this reason, electrophotographic lithographic printing plates prepared by the wet development method are widely used in Japan.

In the electrophotographic lithographic printing plate material used in the electrophotographic lithographic printing plate as described above, the photoconductive zinc oxide itself used as the photoconductive pigment has a photosensitive wavelength range of 3
It exists only in the ultraviolet region of 70 nm. Generally used electronic plate making machine exposes the original with halogen lamp,
The reflected light is exposed to the corona-charged printing plate material, and a lithographic printing plate is obtained through development and drying steps. Therefore, in the electrophotographic lithographic printing plate material using the photoconductive zinc oxide, in order to match the photosensitive wavelength range of the photoconductive layer to the wavelength range of the exposure light source of the halogen lamp, rose bengal, uranine in the photoconductive layer, It has been studied and practiced to add a sensitizing dye such as BPB (bromphenol blue) nigrosine to extend the photosensitive wavelength range.

In recent years, with the development of computers, computers have been remarkably used in the printing industry, and image data are being converted into digital signals. That is, the so-called computer-to-plate method, which is a method of producing computer data on a CRT and producing a lithographic printing plate without making a hard copy, is popular.

What has been a driving force for the development of such plate-making technology is the progress of laser beam technology, and in particular, the semiconductor laser light is capable of downsizing the device and is inexpensive. In addition, a plate making system using a semiconductor laser beam has been developed in recent years by taking advantage of the fact that direct modulation is possible.

Examples of such electrophotographic photosensitive members having sensitivity in the oscillation wavelength range of the semiconductor laser light include, for example, JP-A-1-230062, JP-A-3-168646, and JP-A-3-100559. Japanese Patent Laid-Open No. 4-24
No. 700, Japanese Patent Application Laid-Open No. 4-7557, etc. These are those obtained by spectrally sensitizing using a trimethine cyanine dye to impart sensitivity to a semiconductor laser light having an oscillation wavelength of 780 nm which is near infrared light. However, it has no sensitivity to visible semiconductor laser light having an oscillation wavelength of around 635 nm, which is becoming cheaper recently.

Further, Japanese Patent Laid-Open No. 6-75438 describes a method having sensitivity to a semiconductor laser beam having an oscillation wavelength of 670 nm, but a cyanine dye alone has sufficient sensitivity in the case of a semiconductor laser beam having an oscillation wavelength of 635 nm. Can't get

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic lithographic printing plate material having high sensitivity to semiconductor laser light having an oscillation wavelength of about 635 nm.

[0011]

Means for Solving the Problems As a result of various studies for solving the above problems, the inventors have made the photoconductive layer contain two or more kinds of dye compounds having a specific chemical structure. As a result, the above problems have been successfully solved.

That is, the electrophotographic lithographic printing plate material for laser light of the present invention is a light-sensitive material containing an intermediate layer on one surface of a water-resistant support, a mixture of a photoconductive pigment and an electrically insulating adhesive as a main component. In the electrophotographic lithographic printing plate material for laser light in which conductive layers are sequentially formed, the photoconductive layer has the following general formula (I):

[0013]

Embedded image[However, R₁Is -CH_TwoCOO, -C_TwoH_FourCOO, -C
_ThreeH₆Represents COO, R _TwoIs -CH_TwoCOOH, -C_TwoH_Four
COOH, -C_ThreeH₆Represents COOH. ]
At least one of the dye compounds and tetrabromo
Semiconductor containing enorum blue and oscillating wavelength of 635 nm
It is characterized by having sensitivity to laser light.
You.

In the present invention, the dye compound represented by the general formula (I) in the photoconductive layer is 0.001 to 0.5 with respect to 100 parts by weight of the photoconductive zinc oxide in the photoconductive layer.
Parts by weight, preferably 0.002-0.4 parts by weight.
Further, tetrabromophenol blue is added in an amount of 0.01 to 1. per 100 parts by weight of photoconductive zinc oxide in the photoconductive layer.
It is 0 part by weight, preferably 0.02 to 0.9 part by weight.
When the compounding amount of the dye compound represented by the general formula (I) is less than 0.001 part by weight or the compounding amount of tetrabromophenol blue is less than 0.01 part by weight, a semiconductor laser beam having an oscillation wavelength of 635 nm is emitted. It has no sensitivity.
On the other hand, when the amount of the dye compound represented by the general formula (I) is more than 0.5 parts by weight, or when the amount of tetrabromophenol blue is more than 0.9 parts by weight, the sensitivity is saturated. However, there is no effect of increasing the blending amount, and the cost becomes high.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The photoconductive layer of the present invention comprises a photoconductive pigment such as zinc oxide or titanium oxide, an electrically insulating adhesive, a dye compound represented by the general formula (I) and tetrabromophenol. A coating consisting of blue and a solvent is applied onto the intermediate layer formed on one surface of the water resistant support, and dried to form. The weight of the photoconductive layer after drying is 2
It is preferably in the range of 0 to 30 g / m ² . 20 g /
When it is less than m ² , the image density is low, and when it is more than 30 g / m ² , the charging potential reaches saturation, the image density is not improved, and the cost becomes high. As a method for applying the coating material for the photoconductive layer, a Meyer bar method, an air knife method, a blade method, a reverse roll method, a slit die method, or the like can be used, but the method is not limited to these.

As the electrically insulating adhesive used in the photoconductive layer of the present invention, an acrylic ester copolymer, a methacrylic ester copolymer, a vinyl acetate copolymer, a butyral resin, etc., which are generally hydrophilic, are used. Can be mentioned. For the purpose of improving image quality and the like, it is safe to copolymerize a monomer having a functional group such as acrylic acid, methacrylic acid or maleic acid with these electrically insulating adhesives.

The electrically insulating adhesive contained in the photoconductive layer is preferably 10 to 30 parts by weight, more preferably 15 to 20 parts by weight, based on 100 parts by weight of the photoconductive pigment.

If desired, auxiliary additives such as sensitization aids such as maleic anhydride, phthalic anhydride, cobalt salts and manganese salts may be added to the coating for the photoconductive layer of the present invention.

The water-resistant support of the present invention has water resistance and is a paper, a laminated sheet of paper and an aluminum foil or a polyethylene film, or a plastic film,
It can be selected from paper having a vapor-deposited metal layer and synthetic paper.
Generally, the thickness of the support is preferably about 70 to 150 μm.

For the purpose of preventing etching and curling of the electrophotographic lithographic printing plate material for laser light, or preventing penetration of toner during wet development, the surface of the water resistant support opposite to the surface on which the photoconductive layer is provided. A back layer is formed.

Further, in order to improve the water resistance of the water resistant support of the present invention, an intermediate layer is formed between the water resistant support and the photoconductive layer. Such an intermediate layer and the back layer are formed of a pigment, a binder resin, a conductive agent, or the like.

Examples of pigments that can be used in the intermediate layer and the back layer of the present invention include calcium carbonate, magnesium carbonate, kaolin, talc, calcined clay, silica, diatomaceous earth, mica, synthetic aluminum silicate, zinc oxide, titanium oxide, Examples thereof include inorganic pigments such as aluminum hydroxide and barium sulfate, and organic resin fine powders such as urea-formalin resin, styrene-methacrylic acid copolymer and polystyrene resin.

The pigment content is preferably in the range of 10 to 80% by weight of the solid content of the intermediate layer coating material and in the range of 10 to 80% by weight of the solid content weight of the back layer coating material.

A water-dispersible hydrophobic resin and / or a water-soluble resin can be used as the binder resin used in the intermediate layer coating material and the back layer coating material of the present invention. The content of the water-dispersible hydrophobic resin is preferably in the range of 10 to 80% by weight based on the solid content of the back layer coating material.

Examples of the water-dispersible hydrophobic resin include styrene-butadiene latex, acrylic emulsion,
Examples thereof include vinyl acetate-acrylic acid ester copolymer emulsion, polyurethane emulsion, polyvinyl chloride emulsion, polyvinylidene chloride emulsion, methacrylic acid ester copolymer emulsion and acrylic acid ester copolymer emulsion.

Further, when the water-soluble resin is contained in a large amount, the water resistance is deteriorated. Therefore, it is necessary to use the water-soluble resin in an amount of 10% by weight or less based on the solid weight of the paint in the back layer.
As the water-soluble resin, for example, polyvinyl alcohol, oxidized starch, modified starch, gum arabic, gelatin, casein, chitosan, methyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid salt, polyacrylic amide,
Styrene-maleic anhydride copolymer salt, methyl vinyl ether-maleic anhydride copolymer salt, methyl vinyl ether-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer salt and the like can be used, but of course, There is no limitation.

As the conductive agent used in the intermediate layer and the back layer of the present invention, for example, a cationic conductive resin such as polyvinylbenzyltriammonium chloride, polydimethyldiallylammonium chloride, styrene acrylic acid trimethylaminoethyl chloride copolymer, and the like, Examples thereof include anionic conductive resins such as polystyrene sulfonate, polyacrylate and polyvinyl sulfonate, carbon black and conductive whiskers.

Examples of the auxiliary additive component include a dispersant and a water resistance agent for strengthening the water resistance. As the water resistance agent, for example, glyoxal, glutaraldehyde, a polyvalent aldehyde compound such as dialdehyde starch, a polyamine compound such as polyethyleneimine, an epoxy compound, a polyamide resin, a diglycidyl compound such as glycerin diglycidyl ether, A dimethylol urea compound, an inorganic compound such as ammonium persulfate, ferric oxide, and magnesium oxide, boric acid, or borax can be used, but the present invention is not limited thereto.

The intermediate layer coating material and the back layer coating material can be applied in the same manner as the photoconductive layer coating material.
The coating amount of the intermediate layer and the back layer is 5 to 30 g / dry weight.
It is preferably within the range of m ² .

In order to produce the electrophotographic lithographic printing plate material for laser light according to the present invention, the photoconductive layer coating material is applied onto the intermediate layer formed on one surface of the water resistant support, dried, and The back layer coating material may be applied to the surface of the water resistant support opposite to the surface on which the photoconductive layer is provided and dried.

A barrier layer may be formed between the water-resistant support and the intermediate layer to contain a water-soluble polymer as a main component and prevent the permeation of an organic solvent.

The electrophotographic lithographic printing plate material for laser light of the present invention thus obtained is used as a very excellent printing plate material having a high sensitivity to a semiconductor laser light having an oscillation wavelength of about 635 nm. Can be done.

[0033]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is of course not limited thereto. In each example, "parts" represents "parts by weight".

Example 1 An electrophotographic lithographic printing plate material for laser light was prepared by the following steps (1) to (4), a printing plate was made from the material, and its characteristics were measured and evaluated by the step (5).

(1) Preparation of Water-Resistant Support A coating material for barrier layer having the following composition was applied on both sides of a base paper having a basis weight of 100 g / m ² by a size / press treatment to give a dry coating amount of 2 g.
/ M ² was formed. Barrier layer paint Polyvinyl alcohol 80 parts Sodium polyacrylate 20 parts

(2) Formation of the intermediate layer The above size-pressed base paper (thickness 110 μm)
Apply a coating for the intermediate layer of the following composition on the barrier layer surface of
An intermediate layer having a dry coating amount of 10 g / m ² was formed by drying. Paint for intermediate layer Muscovite _{(* 1)} 40 parts Polyurethane aqueous dispersion _{(* 2)} 40 parts Casein solution 10 parts Silane coupling agent _{(* 3)} 10 parts Note: _{(* 1)} ... Trademark: A-21, Yamaguchi Made of mica, average particle size: 2
0 μm _{(* 2)} … Trademark: Azalux S-1071, Hodogaya Chemical _{(* 3)} … Trademark: SH6040, Toray Dow Corning Silicone

(3) Formation of Back Layer On the surface of the water resistant support opposite to the side on which the photoconductive layer is provided, a back layer coating material having the following composition is applied and dried to obtain a dry coating amount of 1
A back layer of 3 g / m ² was formed. Back layer coating Benzoguanamine-formaldehyde resin _{(* 4)} 5 parts Kaolinite clay dispersion _{(* 5)} 50 parts SBR latex _{(* 6)} 35 parts Polyvinyl alcohol _{(* 7)} 7 parts Sodium polyacrylate _{(* 8) )} 3 parts Note: _{(* 4)} ... Trademark: Eposter L, Nippon Shokubai Kagaku Kogyo _{(* 5)} ... Trademark: HG Clay (US), Huber _{(* 6)} ... Trademark: PT-1004, Nippon Zeon _{( * 7)} ... Trademark: T-330, manufactured by Nippon Synthetic Chemical _{(* 8)} ... Trademark: Primal 850, manufactured by Acrylic Japan After forming the intermediate layer and back layer on the support, the Oken type smoothness of the intermediate layer surface Super calendar processing was performed so as to reach 500 seconds.

(4) Formation of Photoconductive Layer A photoconductive layer coating composition having the following composition was applied onto the intermediate layer,
After drying, a photoconductive layer having a dry coating amount of 25 g / m ² was formed to obtain an electrophotographic lithographic printing plate material for laser light. Photoconductive layer paint Photoconductive zinc oxide _{(* 9)} 100 parts Acrylic resin _{(* 10)} 18 parts Antioxidant _{(* 11)} 0.06 parts Note: _{(* 9)} … Trademark: SAZEX # 2000, Sakai Chemical _{(* 10)} ... Trademark: LR-188, Mitsubishi Rayon _{(* 11)} ... Trademark: 2,6-di-t-butyl-p-cresol (BHT), manufactured by Kawaguchi Kagaku This mixed solution using toluene as a solvent In the general formula (I), R ₁ is —CH ₂ COO and R ₂ is —CH ₂ COO.
A solution prepared by dissolving 0.003 parts of a dye compound representing H and 0.03 part of tetrabromophenol blue in 3 parts of methanol was added, and this mixed solution was dispersed by a sand grinder to obtain a coating material for a photoconductive layer. The electrophotographic planographic printing plate material for laser light thus obtained was subjected to humidity control for 24 hours in the dark at 20 ° C. and 65% RH, and then the sensitivity was measured.

(5) Measurement method PHOTO DECA in the dark at 20 ° C. and 65% RH
The charging characteristics were measured using Y ANALYZING SYSTEM (manufactured by Juntec, CYNTHIA 30.5). Charging is performed with a corona voltage of -6 kV, the light source uses semiconductor laser light with an oscillation wavelength of 635 nm, and light intensity is 3 mW.
/ Cm ² . The charge amount (Vs) is the amount of light required for the charge potential to be halved by light irradiation, with the potential immediately after charging being the charge potential, and the potential (V ₁₀ ) when held for 10 seconds in the dark as it is, Charge retention rate (Vs / V ₁₀ )
× 100 (%) was calculated. Table 1 shows the results.

Example 2 The same operation as in Example 1 was performed. However, in the formula of the dye compound of the general formula (I) in the photoconductive layer, R ₁ is —C ₂ H ₄ CO
O and R ₂ each represent a compound representing —C ₂ H ₄ COOH.
Parts and 0.1 parts of tetrabromophenol blue.

Example 3 The same operation as in Example 1 was performed. However, R _{1 in the} formula of the dye compound of the general formula (I) in the photoconductive layer is —C ₃ H ₆ CO
O and R ₂ are compounds each representing -C ₃ H ₆ COOH.
Parts, and 0.9 parts of tetrabromophenol blue.

Example 4 The same operation as in Example 1 was performed. However, 0.6 parts of the dye compound of the general formula (I) and 1.1 parts of tetrabromophenol blue in the photoconductive layer were used.

Comparative Example 1 The same operation as in Example 1 was performed. However, a compound represented by the following structural formula (II) and tetrabromophenol blue were used as the dye compound.

[0044]

Embedded image

Comparative Example 2 The same operation as in Example 1 was performed. However, a compound represented by the following structural formula (III) and tetrabromophenol blue were used as the dye compound.

[0046]

Embedded image

Comparative Example 3 The same operation as in Example 1 was performed. However, as the dye compound, a compound represented by the general formula (I) [wherein R _{1 in the} formula (I)
Is -CH ₂ COO, R ₂ represents -CH ₂ COOH. ]
Used alone, no tetrabromophenol blue.

Comparative Example 4 The same operation as in Example 1 was performed. However, the compound of the general formula (I) was not used as the dye compound, and only tetrabromophenol blue was used.

[0049]

[Table 1]

As is clear from Table 1, the electrophotographic lithographic printing plates for laser light of Examples 1 to 4 according to the present invention had excellent sensitivity, and the charge amount and the charge retention rate were high. On the other hand, the charge amount and the charge retention rate were at the same level as those in the examples, but the comparative examples 1 to 4 were inferior in sensitivity.

[0051]

EFFECTS OF THE INVENTION The present invention makes it possible to prepare a very excellent electrophotographic lithographic printing plate material for laser light having high sensitivity to a semiconductor laser light having an oscillation wavelength of 635 nm, which is extremely useful industrially. It is something.

Claims (1)

[Claims] 1. An intermediate layer and a photoconductive layer on one surface of a water resistant support.
Containing a mixture of a water-soluble pigment and an electrically insulating adhesive as the main component.
Electrophotographic flat plate for laser light in which the photoconductive layers are sequentially formed.
In the plate printing plate material, the photoconductive layer has the following general formula:
(I):[However, R₁Is -CH_TwoCOO, -C_TwoH_FourCOO, -C
_ThreeH₆Represents COO, R _TwoIs -CH_TwoCOOH, -C_TwoH_Four
COOH, -C_ThreeH₆Represents COOH. ]
At least one of the dye compounds and tetrabromo
Containing Enol Blue and a semiconductor with an oscillation wavelength of 635 nm
Laser having sensitivity to body laser light
Electrophotographic planographic printing plate material for light.