JPH0373392A - Base material for lithographic printer plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a support for a lithographic printing plate. More specifically, the glass transition temperature of the cured product on the paper support is 10
The present invention relates to a support for a lithographic printing plate impregnated with an electron beam curable resin having a temperature of 0° C. or higher, cured by electron beam irradiation, and coated with a resin.

CB) Conventional technology In recent years, lithographic printing plates have been made of aluminum with a smooth surface as a support.
Metal plates such as zinc, stainless steel, and chrome, synthetic resin sheets such as polyethylene terephthalate, paper, and resin-coated paper are used after being subjected to hydrophilic activation treatments such as graining, corona discharge machining, and hydrophilic undercoating. , a silver image area formed by a photographic method, a silver halide image area, a photocurable photosensitive resin image area, a photodegradable photosensitive resin image area, etc. are provided as an ink receiving area.

(C) Problems to be Solved by the Invention Materials used for planographic printing plate supports include metal plates due to their mechanical strength, dimensional stability, printing durability, ease of processing, and resistance to dark reactions. Among these, aluminum plates are particularly good, but they are expensive, heavy, and have the problem of being difficult to bend the edges when installing the printing plate in a printing press. When a synthetic resin such as polyethylene terephthalate is used for the support, the weight is lighter, but the problem remains that the edges are difficult to bend6 Paper, or resin-coated paper, has a low printing capacity It is often used for good light printing 1.) It is inexpensive, light in weight, has good bendability, and does not cause plate elongation even when installed on a printing machine, but has low mechanical strength and does not cause plate elongation when printing a large number of sheets. The problem was that the dimensional stability was poor. In particular, when paper or resin-coated paper is used as a support, the mechanical strength and elongation when tensile force is applied are significantly different between the length (machine direction during paper making) and the width (width direction during paper making) of the base paper. This caused a difference in dimensional stability. In order to improve such dimensional stability and printing durability, there is a method of laminating a synthetic resin with high mechanical strength on the base paper, but even in such a case, the elongation in the lateral direction is significant, It was not a fundamental solution. Therefore, the present invention uses resin-coated base paper to improve mechanical strength and
The goal is to solve problems such as dimensional stability, printing durability, printability, bending characteristics, weight reduction, and handling.

Furthermore, when the paper support is irradiated with an electron beam, the photosensitive resin has the problem of fogging due to decomposition of cellulose and internal additives, which is an inevitable problem when used in lithographic printing plates.

CD) Means for Solving the Problems As a result of intensive research into means for solving the above-mentioned problems, the inventors have found the following solution. That is, in a support for a lithographic printing plate, an electron beam curable resin whose cured product has a glass transition temperature of 100°C or higher is added in an amount of 3% by weight based on the total weight after impregnation.
The above is an invention of a support for a lithographic printing plate, characterized in that a resin coating layer is provided on at least one side of an impregnated paper support containing 30% by weight or less and cured by electron beam irradiation. The present invention will be explained in detail below.

In the present invention, the resin coating layer may be a molten polyolefin resin layer using an electron beam curable resin composition or polyolefin resin that is cured by electron beam irradiation.

After providing a resin coating layer or a polyolefin resin coating layer of an electron beam curable resin composition using a paper support impregnated with the electron beam curable resin of the present invention, the paper/resin coating was cured by electron beam irradiation. The adhesive strength between the photosensitive emulsion layer and the photosensitive emulsion layer is extremely good, and the bendability is good. Even when printing on a lithographic printing plate, there is little printing shift due to plate elongation, which is common when paper is used as a support. It has been found that the paper support does not cause fogging of the photosensitive emulsion layer, which is a problem when the paper support is irradiated with electron beams, and is a good support for lithographic printing plates that is light and easy to handle.

In the present invention, in order to impregnate the paper support with an electron beam curable resin whose cured product has a glass transition temperature of 100°C or higher, the electron beam curable resin is dispersed in what is called white water in the paper industry from the papermaking stage. One method is to adsorb it to the fibers, the other is to adsorb it to the cellulose fibers by dipping it with a means such as a tab after the papermaking process, and applying it to the paper support after dissolving the electron beam curable resin in a solvent such as acetone. There are three methods: impregnation and drying. In these cases, the electron beam curable resin can be used alone, dissolved in a solution, or in the form of an emulsion to improve impregnation.

It is essential for the electron beam curable resin used for impregnation in the present invention that the cured product has a glass transition temperature of 100°C or higher, and also has electron beam curable properties, weather resistance,
The material can be selected in consideration of conditions such as membrane strength, heat resistance, adsorption to the support, and adhesiveness. In addition, the electron beam curable resin used for impregnation has a
It is necessary to impregnate the paper at a ratio of 3% by weight or more and 30% by weight or less, less than 1% by weight. If the ratio is less than this, the expected strength characteristics will not be obtained, and if it is more than this range, the paper will lose its flexibility and the lithography Not only is this undesirable as a support for printing plates, but it is also uneconomical because the amount of electron beam irradiation required to cure the impregnated resin increases.

The electron beam curable resin used in the present invention can be selected in consideration of conditions such as electron beam curing characteristics, dispersibility, weather resistance, strength characteristics, heat resistance, curling characteristics, and adhesiveness to a support. In addition, the electron beam curable resin to be impregnated into paper may be applied in the form of a solution or emulsion, and then cured by electron beam irradiation after drying. Unsaturated polyesters having electron beam-reactive groups, modified unsaturated polyesters, acrylic polymers, polymers having ethylenically unsaturated IPl@ bonds, and monomers can be used alone or in combination with other solvents. Typical types of electron beam polymerizable resins are illustrated below.

(A) Monofunctional acrylate, monofunctional methacrylate (B) Polyfunctional acrylate, polyfunctional methacrylate, polyfunctional oligomer (C) Polyester acrylate, polyester methacrylate (D) Epoxy acrylate, epoxy methacrylate (E) Urethane acrylate, urethane methacrylate, ( F) Polyol acrylate, polyol methacrylate As a result of our research on photographic supports irradiated with electron beams, we found that among the above electron beam curable resins,
If a paper support is impregnated with an acrylate resin with good crosslinking properties and the glass transition temperature of the cured product is 100°C or higher and cured by electron beam irradiation, the interpaper strength after electron beam irradiation will be increased. It was also found that the decomposition of the paper support due to electron beam irradiation was prevented, fogging of the photosensitive emulsion was prevented, and the curling properties were significantly improved. Even if it is impregnated with an electron beam hardening resin whose cured product has a glass transition temperature lower than 100°C and is cured by electron beam irradiation, the expected paper-to-paper strength can be obtained, and it can also suppress the decomposition of the paper support. , it was found that it did not have any significant effect on the curl properties. However, when used alone, the glass transition temperature of the cured product is 100″
Even if the electron beam curable resin is lower than C, it can be used as an impregnating resin if the glass transition temperature of the cured product is 100°C or higher when mixed with an electron beam curable resin having a sufficiently high glass transition temperature and cured. It was also discovered that it could be used.

The electron beam curable resin composition of the present invention contains antioxidants, antistatic agents, and dispersions such as those used in the surface polyethylene layer of planographic printing plate supports prepared by conventional polyolefin resin melt extrusion methods. Various additives such as additives and stabilizers can be added in appropriate combinations.

Furthermore, even if surface treatment such as corona treatment is performed on the paper surface in order to improve the adhesion and wettability between the paper support and the resin coating layer in the present invention, the adhesion and wettability between the resin coating surface and the photosensitive emulsion will not improve. In order to improve the properties, the surface of the resin-coated surface may be subjected to surface treatments such as corona treatment or sub-coat.In addition, the back surface of the lithographic printing plate support of the present invention may be coated with anti-curl,
A back coat layer can be provided to prevent static electricity and provide writability, and the back coat layer may contain an antistatic agent, hydrophilic binder, latex, hardener, pigment, surfactant, etc. in appropriate combination. I can do it.

The base paper used as the support in the present invention can be ordinary natural valve paper, synthetic fibers, or so-called synthetic paper made from synthetic resin film, but wood from softwood valves, hardwood valves, and mixed softwood and hardwood valves can be used. A natural bulb paper based on bulbs is advantageously used. There is no particular restriction on the thickness of the base paper, but a smooth one is preferred, and its basis weight is 30g/rn'' to 300g/r
The base paper containing natural valves as the main component, which is advantageously used in the method of the present invention where n'' is preferable, can contain various polymeric compounds and additives.For example, starch, starch derivatives (cationized starch, phosphoric acid, etc. esterified starch, oxidized starch, etc.), polyacrylamide, polyvinyl alcohol, polyvinyl alcohol derivatives (completely saponified, partially saponified, carboxy-modified, cation-modified, and other various modified polyvinyl alcohols), gelatin (alkali-treated, acid-treated, various Dry paper strength enhancers such as (modified gelatin), natural polymeric polysaccharides such as star gum and alginic acid derivatives, higher fatty acid metal salts, rosin derivatives, dialkyl ketones, alkenyl or alkyl succinic anhydrides, epoxidized higher fatty acid amides, organic fluorocarbons Compounds, sizing agents such as dialkyl ketene dimer emulsions, wet paper strength enhancers such as polyamide polyamine epichlorohydrin resins, melamine resins, urea resins 1, epoxidized polyamide resins, stabilizers, pigments, dyes, antioxidants, fluorescent whitening agents, various latexes, inorganic electrolytes (sodium chloride, sodium sulfate, sodium phosphate, calcium chloride, lithium chloride, magnesium chloride, magnesium sulfate, barium chloride, etc.), pHl1 adjuster, fixing agents such as sulfuric acid band and aluminum chloride, carbonic acid Fillers such as calcium, kaolin, talc, and clay, and additives such as organic conductive agents can be contained in appropriate combinations.These substances may be dispersed in the pulp slurry at the papermaking stage, or they may be dispersed in the pulp slurry at the papermaking stage. The size may be added, or the solution may be applied using various coaters.

The surface of the lithographic printing plate support of the present invention (the side on which the photosensitive resin layer is provided) may contain an antihalation agent such as carbon black, an antistatic agent, and an antioxidant. It improves adhesion to the print area, retains dampening water in non-image areas during printing, improves printing smudges, improves ink adhesion in image areas, improves contrast, sharpness, and printing durability of printed areas. A fine uneven pattern (
Furthermore, the back surface of the lithographic printing plate support of the present invention may be coated with a polyolefin resin by the conventional melt extrusion method, or coated with an electron beam curable resin. The resin coating layer may be formed by a method of forming a film by electron beam irradiation after coating, and a back coat layer may be provided or the surface may be roughened so as to provide writing properties on the back surface.

A general pigment kneading machine can be used as a method for preparing the electron beam curable resin. For example, two rolls,
These include a three-roll mill, a ball mill, a kneader-high speed mixer, and a homogenizer.

Methods for applying electron beam curable resin onto base paper include, for example, blade coating, doctor coating, air knife coating, spray coating, squeeze coating, reverse roll coating, gravure roll and transfer roll coating, extrusion coating, and curtain coating. , die coating, etc. may be used, and it is also possible to impregnate paper with Den-F or line-curable resin and then smooth it with a calender or the like.

The polyolefin resin produced by the melting method used as the coating resin in the present invention includes polyethylene (high density polyethylene, low density polyethylene, medium density polyethylene, linear low density polyethylene), polypropylene, polybutene, polybentene, and other olefin homopolymers or ethylene /propylene copolymers and other copolymers made of two or more olefins, and those having various densities and melt indexes can be used, and these resins can be used alone or in combination.

Among them, polyethylene is particularly advantageously used.

1 consisting of an electron beam polymerizable composition or a molten polyolefin resin! The thickness of the fIFM coating layer varies depending on the type and smoothness of the base paper, but is 2 to 100 μm, more preferably 3 to 5 μm.
0 μm, and if it is thinner than this, it will not have sufficient water resistance, and it will be difficult to apply it uniformly.
If it is thicker than this, it will be difficult to uniformly provide the coating layer, which is not desirable in terms of quality.

When using an electron beam curable resin composition, if the surface of the lithographic printing plate support is to be further mirror-finished or molded, the surface to be treated is brought into contact with a mirror-finished roll or molded roll, and the surface is heated from the back side. It can be hardened by irradiating it with electron beams to give it a mirror finish. Alternatively, there is a method in which the surface is partially cured by preliminary electron beam irradiation, and then brought into contact with a mirror roll or molding roll and subjected to secondary irradiation to completely cure the surface. When using a molten polyolefin resin, a mirror surface or a molded surface can be obtained by using a corresponding cooling roll.

Further, a brimer layer may be provided between the paper support and the resin coating layer to even out the unevenness of the paper support.

For electron beam irradiation, the acceleration voltage is 10 from the viewpoint of penetrating power and curing power.
0 to 1000 KV, more preferably 100 to 30
It is preferable to use a 0KV electron beam accelerator so that the absorption lti amount of one bath is α5 to 2Q Mrad.If the accelerating voltage or the electron beam irradiation amount is lower than this range, the penetrating power of the electron beam will be too low. If sufficient curing is not carried out and the amount exceeds this range, not only will energy efficiency deteriorate, but also unfavorable effects will appear on quality, such as a decrease in the strength of the base paper and decomposition of the resin and additives. The electron beam accelerator may be, for example, an electrocurtain system, scanning tie 1, double scanning type, or the like.

Note that during electron beam irradiation, a high oxygen concentration will hinder the curing of the electron beam curable resin, so especially when using an electron beam curable resin as a coating resin, replacement with an inert gas such as nitrogen, helium, or carbon dioxide is recommended. to reduce the oxygen concentration to 60
It is preferable to irradiate in an atmosphere in which the concentration is suppressed to 0 ppm or less, preferably 400 ppm or less.

The lithographic printing plate support prepared according to the present invention can be prepared by coating a photosensitive resin or a photosensitive emulsion thereon.
It can be used as a lithographic printing plate. Here, the lithographic printing plates include Tokko No. 48-16725 and No. 51-29.
No. 446, No. 48-60562, No. 51-15764
No. 51-16803, Utility Model Application No. 51-111103
No. 51-139401, U.S. Patent No. 3,721゜559, U.S. Pat.
No. 06902, No. 52-112402, No. 53-21
No. 602, No. 53-21601, etc., which use a silver image area of a negative type eye as ink receptivity, U.S. Patent No. 3.4.
No. 54.398, No. 3,764,323, No. 3,
No. 099,209, JP-A No. 47-46002, No. 53
-9603, No. 53-102105, etc., in which the silver halide image area is used as ink receptivity, a silver complex diffusion transfer method, a physical development method, a chemical development method, an etching bleach method, a hot-shoe-off method, etc. Alternatively, a lithographic printing plate using a silver image area or a silver halide image area formed by a photographic method by a combination method as ink receptivity, a diazo compound, an azide compound, a water or aqueous solution development type, or an organic solvent development type photocuring type or photo Used in lithographic printing plates using decomposable photosensitive resins, direct anchor lithographic printing plates, waterless lithographic printing plates using photosensitive silicone resin, so-called electrophotographic printing plates coated with organic-inorganic photoconductive substances, etc. be able to.

[E] Examples Hereinafter, the present invention will be explained in detail with reference to Examples, but the content of the present invention is not limited to the Examples.

Example 1 A support for a lithographic printing plate was prepared by the following method.

Paper is made from a valve slurry consisting of 0.1 part of alkyl ketene dimer as a sizing agent, 05 parts of polyamide polyamine shrimp chlorohydrin resin as a wet strength agent, and 0.3 g of polyacrylamide as a dry strength agent per 100 parts of pulp, and after pressing, the paper is made into a drum. Dry with a hair dryer.
A base paper of g/m' was obtained.

This base paper was coated with an electron beam curable resin tris(2-hydroxyethyl)incyanuric acid acrylic acid ester using A7T as a solvent (Tg of cured product: 166℃, average weight jik3
Tabize to 0g#n'.

The paper was impregnated with the paper and dried in an explosion-proof hot air dryer to obtain impregnated paper. The dried impregnated paper was smoothed with a supercalender, then corona discharge treated on both sides, and then the paper was coated with low-density polyethylene (density α918 g/am', MI 5) and high-density polyethylene (density 0.965 g/cm'ML7). Both sides were laminated using a melt extrusion method to an average thickness of 20 JJ. The impregnated paper coated with the laminate was guided into an electron beam ffJt device (Curetron, manufactured by Nissin Electric Co., Ltd.) that had been replaced with nitrogen (oxygen concentration 200 ppm), and impregnated by electron beam irradiation under the conditions of an acceleration voltage of 2° OKV and an absorbed dose of 4 Mrad. The resulting electron beam curable resin was cured to obtain a support for a lithographic printing plate (Sample 1).

Example 2 The type of electron beam curable resin impregnated into the base paper in Example 1 was trimethylolpropane triacrylate (Tg of cured product: 250'C or more), and the average weight of impregnation was 4.5 g/
The reverse side of the impregnated paper changed to rrr' was coated with a polyethylene mixture with an average thickness of 20 μm, and the surface was coated with 75 parts of low-density polyethylene (density α918 g/cm3MI5) and high-density polyethylene (density 0) as a brimer layer. .965g/cm3, MI 7)25
The laminate was coated with a 13 μm thick polyethylene mixture.

After corona treatment was performed on the surface of the brimer layer, an electron beam curable resin composition having the following composition was applied as a resin coating layer using an offset gravure coater to an average thickness of 7 μm, and was coated in the same manner as the practical PAl. The impregnated electron beam curable resin and the electron beam curable resin composition coated on the surface were cured by electron beam irradiation under the following conditions, and a resin coating layer was provided to obtain a support for a lithographic printing plate (Sample 2).

(Electron beam curable resin composition) 50% by weight of bisphenol A diacrylate, 49.5% by weight of pentaerythritol triacrylate, and 05% by weight of perfluoroalkyl acrylate were mixed using a triple roll to create an electron beam curable resin. It was made into a composition.

Example 3 The types of electron beam curable resins impregnated into the base paper in Example 1 were α,ω-tetraacryloyl-(bistrimethylolpropane)-tetrahydrophthalate and polyoxyalkylene (02-3) bisphenol A diacrylate. A dry impregnated paper obtained in the same manner as in Example 1 except that an isotemperature mixture (Tg of cured product: 105 ° C.) and an average impregnation weight of 60 g/m' was smoothed with a supercalender, and then carried out. The impregnated electron beam curable resin was cured by electron beam irradiation using the same electron beam irradiation device as in Example 1 at an acceleration voltage of 20 flV and an absorbed dose of 2 Mrad to obtain an impregnated cured paper. The back side of the impregnated hardened paper was subjected to corona discharge treatment, and the same polyethylene mixture as in Example 1 was used to
Melt-press laminate coating was performed to an average thickness of 20 μm, and the same electron beam curable resin composition as in Example 2 was applied to the surface of the impregnated cured paper to an average thickness of 20 μm, and an accelerating voltage of 20 kV was applied.
Electron beam irradiation was performed under the conditions of an absorbed dose of 2 Mrad to cure the electron beam curable resin composition and provide a resin coating layer to obtain a support for a lithographic printing plate (Sample 3).

Comparison gAJl The i paper obtained in Example 1 was dried with hot air without being impregnated with an electron beam curable resin, smoothed with a super calender, and then corona discharge treated on both sides to form the same polyethylene as in Example 1. The mixture was laminated to an average thickness of 20 μm on both sides by melt extrusion to obtain a support for a lithographic printing plate (Sample 4).

Comparative Example 2 Sample 5) was prepared in which a support for a lithographic printing plate was obtained in the same manner as in Example 2, except that the average weight of the electron beam curable resin impregnated into the base paper was 2 g/ba.

Comparative Example 3 In Example 2, the type of electron beam curable resin impregnated into the base paper was tripropylene glycol diacrylate with a cured product Tg of 90"C, and the average impregnation weight was 30 g/rr.
A lithographic printing plate elbow support was obtained in the same manner as in Example 2 except for Sample 6).

Comparative Example 4 In Example 3, the type of electron beam curable resin impregnated into the base paper was 8 mol of propylene oxide modified pentaerythritol tetraacrylate with a cured product Tg of 0°C or less, and the average impregnated weight was 75 g/d. A support for a lithographic printing plate was obtained in the same manner as in Example 3 except for this (Sample 7).
.

Preparation of Planographic Printing Plate The supports for planographic printing plates obtained in Examples and Comparative Examples were treated with a gelatin mat layer containing silica particles with an average particle size of 5 μm on the back surface after being subjected to corona discharge treatment. After corona discharge treatment, thyroid 7
4 (manufactured by Fuji Davison Co., Ltd., silica fine particles with an average particle size of 7 μm), formalin, and a gelatin solution containing carbon black at 3 g/rr so that the light reflectance after curing is 5%.
It was applied at an average weight of l. High-sensitivity silver chloride emulsion N spectrally sensitized with cyanine dye (gelatin 1
．． 5 g/rn', 1.5 g of silver halide in terms of silver nitrate
Then, 7.5 mg/rT+2> of Polmarin was applied, dried, and then heated at 40° C. for 14 days. On this emulsion layer, a core coating solution (polymer No. 3, acrylamide and imidazole copolymer) described in Example 2 of JP-A-53-21602 was applied and dried to prepare a lithographic printing plate material. . After imagewise exposing the lithographic printing plate material thus obtained, a silver complex diffusion transfer developer (water: 700 ml, potassium hydroxide: 20 g, anhydrous sodium sulfite 50 g, 2-mercaptobenzoic acid i.
1: 1.5g, 2-methylaminoethanol: 15g,
Add more water to make 1 liter) and neutralize (water:
600ml, citric acid: 10g, sodium citrate;
A silver image was formed and a lithographic printing plate was obtained.

The obtained lithographic printing plate was mounted on an offset printing machine, and a desensitizing solution (water: 60Qml, isopropanol: 400ml) was added to the offset printing machine.
1.3-mercapto-4-acetamido-5-n-hebutyl-1,2,4-triazole: 1 g) and dampening liquid (0-phosphorus vi: 10 g, Nigel nitrate = 5 g, sodium sulfite = 5 g, ethylene Glycol: 100g,
Printing was performed using a 20% colloidal silica solution (28 ml (add water to make 1 liter)).

Evaluation Evaluation of plate elongation during printing was performed on the 1st and 30th printed sheets.
This was carried out by actually measuring the deviation of the image of the 00th printed matter, and the evaluation was made based on the percentage of the deviation length with respect to the length of the entire plate. The lithographic printing plate was mounted on the printing machine vertically or horizontally, and the plate with the larger deviation of the printed image was evaluated as the plate elongation of the sample. The sample number of the lithographic printing plate support produced in the example was used as the sample number of the printed matter printed with the lithographic printing plate using the lithographic printing plate support. The amount of electron beam curable resin impregnated into the lithographic printing plate support was expressed as the weight ratio (% by weight) of the impregnated electron beam curable resin to the weight of the entire impregnated paper.

Printability is determined by curl characteristics as a lithographic printing plate, ease of handling, ink coverage (number of sheets counted from the time the ink is applied until a print with good image density is obtained), and ground staining (3
Characteristics necessary for a printing plate, such as the degree of staining of printed matter after printing 1,000 sheets, were comprehensively judged, and only defective points were annotated. The results of the evaluation are shown in Table 1.

Table 1 CG) Effects of the Invention As is clear from Table 1, in the present invention, since the base paper is impregnated with an electron beam curable resin having good crosslinking properties, a resin coating layer is provided to provide support when cured by electron beam irradiation. It is possible to produce a high-quality lithographic printing plate support that suppresses decomposition of the emulsion and fog of the photosensitive emulsion layer and has good printing properties.

Note 2: Difficulty in curl aptitude

Claims (3)

[Claims] (1) The glass transition temperature of the cured product in the paper support is 100℃
A resin coating layer is formed on at least one side of the impregnated paper support, which contains the above electron beam curable resin in a proportion of 3% by weight or more and 30% by weight or less based on the total weight after impregnation, and is cured by electron beam irradiation. A support for a lithographic printing plate, characterized in that it is provided with. (2) the resin coating layer is composed of an electron beam curable resin,
The support for a lithographic printing plate according to claim 1, which is a layer cured by electron beam irradiation. (3) The support for a lithographic printing plate according to claim 1, wherein the resin coating layer is a polyolefin resin.