JP3522450B2 - Plate making method of lithographic printing plate - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lithographic printing plate capable of obtaining an image having high resolution, requiring no handling under a bright room and a processing solution, and being particularly low in manufacturing cost. The present invention relates to a printing plate making method used for printing.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image portion that accepts oily ink and an oil repellent non-image portion that does not accept ink, and generally the non-image portion is composed of a hydrophilic portion that accepts water. Has been done. In normal lithographic printing,
Both water and ink are supplied to the plate surface, and the image area is supplied with ink.
Printing is performed by selectively receiving water in the non-image area and transferring the ink on the image area to a printing medium such as paper.

At present, a lithographic printing plate is manufactured by providing a lipophilic ink-receiving layer on a base material such as an aluminum plate, a zinc plate, or a paper whose surface is hydrophilized. Among them, those using a photosensitive material such as a diazo compound or a photopolymer on a metal support whose surface is hydrophilically treated, called a PS plate, or silver halide as a photosensitive material on a paper or plastic support. Generally, an image is formed using a silver complex salt diffusion transfer method (DTR method).

A method of forming an ink receiving layer (hereinafter referred to as an image layer) with a diazo compound or a photopolymer is as follows. First, a photosensitive material such as a diazo compound or a photopolymer is formed on a base material such as a metal plate, paper, a laminated plate or an insulating substrate. Apply material. Then, the photosensitive material is irradiated with light to cause a chemical change in the photosensitive material, thereby changing the solubility in the developing solution. Photosensitive materials are classified into two types according to the type of chemical change. As the functional group of the light-irradiated part changes and the negative type becomes insoluble in the developer by the polymerization and curing of the light-irradiated part, the solubility in the developer is changed. It is a positive type. In either case, the photosensitive material insoluble in the developer, which remains on the substrate after the treatment with the developer, becomes the image layer.

On the other hand, lithographic printing plates using the DTR method, particularly lithographic printing plates having a physical development nucleus layer on a silver halide emulsion layer are disclosed in, for example, US Pat. Nos. 3,728,114 and 4,4. No. 134,769, No. 4,160,670,
No. 4,336,321, No. 4,501,811
No. 4,510,228, No. 4,621,04
No. 1, etc., the exposed silver halide crystal undergoes chemical development by DTR development to become black silver and forms a hydrophilic non-image area, while unexposed silver halide crystal. The crystals become a silver salt complex by the complexing agent in the developer and diffuse to the physical development nuclei layer on the surface, causing physical development due to the presence of nuclei to form an image part mainly composed of ink-receptive physically developed silver. Form.

When forming an image layer using the above-mentioned photosensitive material, the exposure method is one of the important factors that determine the resolution. In the past, the mainstream was to prepare an exposure film and then carry out a contact exposure method using ultraviolet light or white light. However, with the progress of computers, a digital signal from computer information is transmitted to an exposure apparatus (computer to plate),
A laser direct writing method of directly exposing a photosensitive material using a laser has been performed. The laser direct writing method has advantages such as low cost, high speed, and high productivity in high-mix low-lot production.

In order to support this laser direct writing method, it is necessary to increase the optical sensitivity of the photosensitive material. Since a diazo compound or a photopolymer is accompanied by a photochemical reaction, it has a low optical sensitivity of several to several hundred mJ / cm ² .
Therefore, the laser output device must have a high output,
There are problems that the device becomes large and the cost becomes high.

Further, in the case of forming an image by the DTR method using silver halide, the sensitivity is several μJ / cm ² and it can be sufficiently exposed even with a simple semiconductor laser, but conversely, before the exposure step is performed. There is a drawback that the efficiency of the production and plate making operations is remarkably deteriorated, because the storage up to and the step of applying to the substrate must be performed in the dark or under a safety light. Also, with diazo compounds and photopolymers, the reaction proceeds even under room light and sunlight,
The reactivity changes even at high temperatures. Furthermore, the presence of oxygen acts as an inhibitor of the reaction. Therefore, before the exposure and the development, the dark room treatment and the storage in the low oxygen state were required similarly.

Further, in the above-mentioned image forming method, it is general to carry out liquid processing such as using a developing solution, and there is a drawback that the processing of waste liquid is an environmental problem.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to cope with a direct drawing method using a laser, which is capable of obtaining an image having a high resolution in the plate making technology of a lithographic printing plate, and is particularly suitable for a bright room. An object of the present invention is to provide a plate-making method for a lithographic printing plate which is extremely excellent in workability in that an image can be obtained even under it and no waste liquid is generated.

[0011]

Means for Solving the Problems The present inventors have found the following inventions as a result of extensive studies to solve the above problems.

The method of making a lithographic printing plate according to the present invention is a lithographic printing plate precursor comprising a support having a hydrophobic surface and at least a hydrophilic layer as the outermost layer. The hydrophobic surface of the lithographic printing plate support is exposed by heating with the above. Therefore, the presence or absence of this heating causes a difference between the hydrophobic portion and the hydrophilic portion on the lithographic printing original plate. That is, when the plate is made by the plate making method of the lithographic printing plate of the present invention and the printing is started by mounting the plate on a lithographic printing machine, there is no hydrophilic layer as the outermost layer and the exposed portion is the hydrophobic layer or the support surface. Receives the ink and becomes the image area, and the hydrophilic layer, which is the outermost layer, remains as it is in the non-heated area, so that it becomes the non-image area of the ink non-acceptance (water reception) and lithographic printing becomes possible.

In the lithographic printing plate making method of the second aspect of the present invention, a light absorber is contained in at least one layer of the lithographic printing original plate. Since it is possible to efficiently absorb the energy such as the above and effectively expose the hydrophobic surface of the support, it becomes possible to use a laser having a lower output. Therefore, the cost of the device can be reduced and the work efficiency can be improved.
The light absorber may be contained in a plurality of layers.

The light absorbing agent may be a dye or a pigment whose absorption wavelength substantially matches the emission wavelength of the laser used. For example, it is preferable to use black one such as carbon black that can absorb light in a wide wavelength band.

Further, in the lithographic printing plate making method of the third aspect of the present invention, a light absorbing agent is contained in the support of the lithographic printing original plate to further improve the energy absorption efficiency of the laser. You can Further, when the addition of the light absorber to the hydrophilic layer has an adverse effect on the hydrophilicity or the adhesiveness to the support, the addition of the light absorber to the hydrophilic layer is excluded or the addition amount is reduced. Then, the ability as a printing plate can be improved.

Further, in the method of making a planographic printing plate of the fourth aspect of the present invention, the hydrophilic layer of the planographic printing original plate contains the acrylamide polymer represented by the following general formula 1 in the hydrophilic layer. As a result, the water receptivity (hydrophilicity) during lithographic printing is maintained for a long period during printing to repel ink, and good printing can be performed without stains (background stains) on non-image areas. Further, the general formula 1 used in the present invention
The polymer content is preferably 300 mg / m ² or less, more preferably ^{2 to} 150 mg / m ² .

[0017]

[Chemical 2]

In the formula, R1 represents a hydrogen atom or an alkyl group, R2 represents a hydrogen atom or an alkali metal atom,
n is 1 to 100 mol%, m is 0 to 50 mol%, l is 0 to
It is 5 mol%. And the average molecular weight is 2000 to 300,000.

According to the present invention, by heating with a laser according to a desired image, it is possible to easily make a lithographic printing plate without using a liquid developer or a device for performing the treatment. Further, it is possible to work in a bright room from the manufacturing process of the lithographic printing plate precursor to the plate making process and the printing process, and it is possible to store the lithographic printing plate in a bright room and under oxygen for a long period of time.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a lithographic printing original plate according to the present invention. The lithographic printing original plate (a) according to the present invention is provided so that a hydrophobic resin 12 is coated on the front and back surfaces of a paper base 11 of a support 1, and a hydrophilic layer as an upper layer (outermost layer) thereof. 3 is provided.
In the plate-making method of the planographic printing plate of the invention, first, the planographic printing plate (a) is irradiated with a laser in a desired image manner. Here, the hydrophilic layer 3 in the portion irradiated with the laser is thermally melted and / or thermally decomposed, and the resin 12 is exposed to complete the plate making. After that, when it is mounted on a lithographic printing machine, ink is received in the exposed portion of the hydrophobic resin 12 and water is received in the remaining hydrophilic layer 3 to enable printing.

The hydrophilic layer of the lithographic printing original plate according to the present invention is mainly composed of a hydrophilic polymer capable of forming a film, and is coated so that at least the outermost layer is the hydrophilic layer. There may be a plurality of hydrophilic layers. Further, the amount of hydrophilic polymer constituting the hydrophilic layer may be in the range of 0.5 to 10 g / m ² per layer.

Examples of the hydrophilic polymer forming such a hydrophilic layer include the following examples, which can be used as a mixture of two or more kinds in view of printing performance such as scumming resistance and printing durability. .

Among the natural products, those obtained from algae such as starches, seaweed mannan, agar and sodium alginate, plant mucilages such as mannan, pectin, tragacanth gum, karaya gum, xanthine gum, guar gum, locust bin gum and gum arabic, Dextran,
Homopolysaccharides such as glucan, xanthan gum, and levan, microbial mucilages such as succinoglucan, pullulan, curdlan, and heteropolysaccharides such as xanthan gum, proteins such as glue, gelatin, casein and collagen, chitin and its derivatives, etc. Can be mentioned.

Further, as semi-natural products (semi-synthetic products),
Cellulose derivatives, modified gums such as carboxymethyl guar gum, and modified starches such as dextrin and other baked starches, oxidized starches, esterified starches and the like can be mentioned.

The synthetic products include polyvinyl alcohol, partially acetalized polyvinyl alcohol, allyl-modified polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl isobutyl ether, and other modified polyvinyl alcohol, polyacrylic acid salts, and polyacrylic acid ester partial soaps. Compound, polymethacrylate,
And polyacrylic acid derivatives such as polyacrylic amide and polymethacrylic acid derivatives, polyethylene glycol,
Examples thereof include polyethylene oxide, polyvinylpyrrolidone, vinylpyrrolidone / vinyl acetate copolymer, carboxyvinyl polymer, styrene / maleic acid copolymer, and styrene / crotonic acid copolymer.

Of these, gelatin, modified and unmodified polyvinyl alcohol, and cellulose derivatives can be advantageously used.

As the gelatin used in the hydrophilic layer of the lithographic printing plate precursor of the present invention, any gelatin derived from animal collagen can be used, but pig skin, cow skin,
Also, gelatin obtained from collagen obtained from cow bone is preferable. The type of gelatin is also not particularly limited, but in addition to lime-treated gelatin and acid-treated gelatin, Japanese Patent Publications No. 38-4854, No. 39-5514, and No. 40-12.
No. 237 and No. 42-26345, U.S. Patent Nos. 2,525,753, 2,594,293, 2,614,928, 2,763,639, and No. 3,118,766, No. 3,132,945, No. 3,186,846, No. 3,312,553,
Examples thereof include gelatin derivatives described in British Patent No. 1,033,189 and the like, and these can be used alone or in combination of two or more kinds.

When gelatin is used in the hydrophilic layer, it can be hardened with a gelatin hardener. Examples of gelatin hardeners include inorganic compounds such as chrome alum,
Aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylal compounds such as urea and ethyleneurea, mucochloric acid, 2,3-
Aldehyde analogs such as dihydroxy-1,4-dioxane, 2,4-dichloro-6-hydroxy-S-
Triazine salt and 2,4-dihydroxy-6-chloro-
Compounds having active halogen such as S-triazine salts, divinyl sulfone, divinyl ketone and N, N, N-
One or two of triacryloylhexahydrotriazine, compounds having two or more ethyleneimino groups or epoxy groups which are active three-membered rings in the molecule, and various compounds such as dialdehyde starch as a polymer hardener. More than one species can be used.

The content of the acrylamide polymer represented by the general formula 1 is preferably 300 mg / m ² or less, more preferably in the range of ^{2 to} 150 mg / m ^2. In consideration of the characteristics, it is in the range of 10,000 to 500,000, more preferably 50,000 to 300,000.

The hydrophilic layer of the lithographic printing original plate according to the present invention may contain an inorganic substance such as titanium oxide, silicon dioxide, aluminum oxide or the like for the purpose of preventing printing stains. The content ratio is appropriately determined in a desired range according to various conditions such as printing ink used for printing, fountain solution, printing speed and printing pressure.

In order to coat the hydrophilic layer of the lithographic printing original plate according to the present invention, some of anionic, cationic or nonionic surfactants may be used as an auxiliary agent, a matting agent, Thickeners, antistatic agents and the like can also be used.

The support having a hydrophobic surface of the lithographic printing plate precursor according to the present invention is a resin-coated paper, a synthetic paper, a synthetic or semi-synthetic polymer film such as polyethylene terephthalate, or a metal plate such as aluminum or iron. It is sufficient that at least the surface thereof has a hydrophobic surface that accepts the ink when both the ink and water are applied and can withstand lithographic printing. Further, the surface of these supports can be subjected to a surface treatment for improving the adhesion with a layer coated as an upper layer, or a dyeing treatment for improving the laser beam absorbability.

In the lithographic printing original plate according to the present invention, a hydrophobic layer may be further provided on the surface of the support for the purpose of improving printing performance such as printing durability and ink riding property. This hydrophobic layer is preferably formed of a synthetic resin (polymer) which has good ink receiving performance, good adhesion to the surface of the support and good adhesion to the hydrophilic layer, and good film formation. For example, (meth) Acrylic resin, vinyl acetate resin, polyethylene resin, polypropylene resin, polybutadiene resin, vinyl chloride resin, vinyl acetal resin, vinylidene chloride resin, styrene resin, polyester resin, polyamide resin, phenol resin, xylene resin, alkyd resin,
Etc. can be mentioned. Two or more kinds of these resins may be mixed and used as necessary, and a plurality of layers may be used.

In the method of making a planographic printing plate of the present invention,
The laser used for heating the hydrophilic layer to expose the hydrophobic surface of the support includes carbon dioxide laser, nitrogen laser, Ar laser, He / Ne laser, He / Cd laser, gas laser such as Kr laser, and liquid. (Dye) laser,
Ruby laser, solid-state laser such as Nd / YAG laser, G
Examples thereof include semiconductor lasers such as aAs / GaAlAs and InGaAs lasers, KrF lasers, XeCl lasers, XeF lasers and excimer lasers such as Ar ₂ .

In the lithographic printing plate making method of the present invention,
Thermal melting of the hydrophilic layer of the lithographic printing original plate relating to the invention and / or
Alternatively, in order to improve the efficiency of accelerating thermal decomposition and exposing the surface of the support (that is, the sensitivity of the lithographic printing original plate in the method of the present invention), the hydrophilic layer, the support, or the lithographic printing original plate is composed of a plurality of layers. In that case, the light absorber is contained in any of the layers other than the hydrophilic layer.

The light absorber may be any dye or pigment, and examples thereof include carbon black, cyanine, metal-free or metal phthalocyanine, metal dithiolene, and anthraquinone.

When the metal support contains a light absorber, a chemical or electrochemical metal coloring method generally called black dyeing can be used. Particularly in the case of an aluminum support, an organic or inorganic dye is immersed in a support that has been anodized in advance, and the dye is introduced into the fine pores of the anodized film, followed by sealing and dyeing. can do.

[0039]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 A 135 g / m ² double-sided polyethylene-coated paper (RC paper) was provided on one side with a matting layer containing silicon dioxide particles having an average particle size of 5 μm, and on the opposite side, carbon black, with an average particle size. A coating liquid consisting of 7 μm silicon dioxide particles, 2,4-dichloro-6-hydroxy-S-triazine sodium as a hardening agent, and gelatin (added so as to be 3.5 g / m ² ) was applied to make it hydrophilic. The characteristic layer A was provided. Furthermore, a polymer of the general formula 1 (wherein R1 and R2 represent a hydrogen atom, n = 78 mol%, m = 10 mol%, l
= 2 mol%. The average molecular weight is 100,000. ) A coating liquid was prepared, and the polymer was coated at 20 mg / m ² and dried to prepare hydrophilic layer B, and a lithographic printing plate precursor having two hydrophilic layers was prepared.

Next, a semiconductor laser irradiation device (830n
In m), the original plate (the surface having the hydrophilic layer B as the outermost layer) was irradiated with laser light in a portion corresponding to the image area to expose the surface of the support to obtain a printing plate. Using this printing plate, an offset printing machine (Ryobi Imagix Co., Ltd. 3200
When printing with MCD), from the first stage of printing,
Ink is deposited on the exposed surface of the support,
It was possible to obtain a good printed matter with no stain on the non-image area up to 1,000 sheets.

Storability test After the lithographic printing plate precursor prepared in the same manner as above was stored in a bright room at 30 ° C. for 6 months, an attempt was made to make a printing plate in the same manner as described above. We were able to obtain a printing plate that was comparable to the printing plate.

Example 2 A matting layer containing silicon dioxide particles having an average particle size of 5 μm was provided on one side of a PET (polyethylene terephthalate) film having a thickness of 175 μm, and the other side was provided with
A metal-free phthalocyanine pigment and polymethylmethacrylate (average molecular weight 30,000) were used to prepare a coating solution using xylene as a solvent, which was then coated and dried to form a hydrophobic layer (film thickness 2 μm).

Next, carbon black, average particle size 7 μ
m silicon dioxide particles, N-methylolethylene urea as a hardening agent, and gelatin (added to give 2.5 g / m ² ), and a polymer of the general formula 1 (wherein R 1 and R
2 represents a hydrogen atom, n = 80 mol%, m = 0 mol%,
1 = 0 mol%. The average molecular weight is 30,000. ) 1
A coating liquid added so as to have a concentration of 00 mg / m ² was prepared and applied as a hydrophilic layer C to prepare a lithographic printing original plate.

A hydrophilic layer corresponding to the image area was irradiated with a semiconductor laser irradiation device (830 nm) to expose the hydrophobic layer to obtain a printing plate. When printing was performed in the same manner as in Example 1 using this printing plate, it was possible to obtain a printed material with good ink coverage without stains on the non-image area from the initial stage of printing to 40,000 sheets.

Example 3 A grained and anodized aluminum plate having a thickness of 0.24 mm was treated with a dye for aluminum (San San Co., Ltd.).
Odal deep black MLW) was used to stain black in a conventional manner.

Next, two hydrophilic layers, hydrophilic layer A and hydrophilic layer B used in Example 1, were coated on the support to prepare a lithographic printing plate precursor.

Using the same semiconductor laser irradiation apparatus as in Example 1, the drawing speed was set to 1.3 times that in Example 1, and the hydrophilic layer corresponding to the image area was irradiated with laser to expose the surface of the aluminum plate , and the printing plate was exposed. Got Using this printing plate, printing was carried out in the same manner as in Example 1. From the initial stage of printing, 1
Up to 0,000 sheets, stains and the like on the non-image area did not occur, and it was possible to obtain a printed matter with good ink coverage.

[0049]

As described above, the lithographic printing plate making method and the lithographic printing plate precursor of the present invention are different from the conventional lithographic printing plate making method using a diazo compound or a photopolymer and can be operated in a bright room. The working environment is very good because it can be performed and no developer is used. In addition, it is possible to deal with a direct writing method using a low-power laser, and an excellent effect that an image having high resolution can be obtained at low cost is brought about.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a lithographic printing plate precursor according to the invention.

[Explanation of symbols]

1 support 11 Paper base 12 resin 3 Hydrophilic layer

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 8-108660 (JP, A) JP-A 7-164773 (JP, A) JP-A 55-105560 (JP, A) JP-A 53- 36301 (JP, A) JP-A-50-113307 (JP, A) International Publication 94/018005 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41N 1/14 B41C 1 / 10 G03F 7/00 503

Claims (3)

(57) [Claims] 1. In a lithographic printing plate comprising a support having a hydrophobic surface and at least a hydrophilic layer as the outermost layer, the polymer represented by the following general formula 1 is used in the hydrophilic layer in the image area. A plate-making method for a lithographic printing plate, comprising exposing the hydrophobic surface of the lithographic printing plate by heating the hydrophilic layer with a laser. [Chemical 1] (In the formula, R1 represents a hydrogen atom or an alkyl group, and R2
Represents a hydrogen atom or an alkali metal atom, and n is 1 to 1.
00 mol%, m is 0 to 50 mol%, and 1 is 0 to 5 mol%. And the average molecular weight is 2000 to 300,000. ) 2. The plate-making method for a plate-making printing plate according to claim 1, wherein a light absorber is contained in at least one layer of the planographic printing plate. 3. The lithographic printing plate making method according to claim 1, wherein the support of the lithographic printing plate contains a light absorber.