JPS6158825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel lithographic printing plate material having an ink-repellent fluorine-containing compound layer in the non-image area and capable of printing without using dampening water, and a method for producing the same. It is related to.

In lithographic printing, a plate is used that does not have clear unevenness on the plate surface like a letterpress or intaglio printing plate, and has an image area and a non-image area on the same plane in appearance.
This lithographic printing method is carried out as follows. In other words, since water and oils repel each other, the non-image areas are made hydrophilic by chemical or mechanical treatment, and the image areas are transferred with lipophilic resin or exposed with photosensitive resin. The ink is made lipophilic by development, etc., and then firstly, water is transferred to this printing plate so that water adheres only to the hydrophilic non-image area, and then ink is further transferred to this printing plate. does not adhere to non-image areas where water is present, but only to lipophilic image areas, so it is then transferred to the printing substrate via a printing substrate or blanket to achieve the desired effect. This is done through the process of obtaining printed matter.

However, various drawbacks caused by the use of dampening water have been pointed out in this currently widely used lithographic printing method. That is, for example, the transfer of the dampening water to the ink roller causes emulsification of the ink on the ink roller, which tends to cause soiling, and the transfer of the dampening water to the printing substrate causes the emulsification of the ink on the ink roller. This causes a change in the dimensions of the image, so it has a major drawback, especially in multicolor printing, in that the printed image becomes unclear.

In order to improve these disadvantages of conventional lithographic printing methods, much attention has been paid to the development of lithographic printing materials that do not require dampening water. From the end of the 1960s to the 1970s
Toward the beginning of the 1990s, Harry Frank Geib of the United States (Special Publication No. 44-23042) and 3M Company of the United States (Special Publication No. 16044 of 1972) published a waterless lithography method that utilized the ink repellency of silicone rubber. It was done. Since then, many patent proposals have been made to date, including a method of using a fluorine-containing polymer instead of silicone rubber as an ink-repellent layer (Japanese Patent Publication No. 1176/1976, etc.). Looking at the layer structure only for those that use silicone rubber as an ink-repellent layer, it is accepted as a common design philosophy to have a silicone rubber resin (rubber) layer on the top layer as an ink-repellent layer. A method of imparting a photosensitive function to a silicone resin layer (for example, Japanese Patent Application Laid-Open No. 51-120804
There are two main methods: methods in which a non-photosensitive silicone rubber layer is coated on a photosensitive resin layer and photoadhesion is expected at the interface between both layers (e.g., Japanese Patent Application Laid-open No. 50-59103). Ru. The former method requires unreasonable efforts in designing the chemical composition of the printing plate in order to expect a number of contradictory functions such as photosensitivity, developability, ink repellency, and plate strength in the layer, and the above-mentioned four It is difficult to maintain a high level of balance between two functions.

In the latter method, although it is said that there is a photoadhesion phenomenon at the interface between both layers, petroleum-based solvents with a high risk of flammability are used to develop and elute the silicone layer, and silicone rubber is used to maintain developability. Because it is necessary to keep the molecular weight and degree of crosslinking of the layer as low as possible, the strength of the plate surface is insufficient, and there are defects such as the plate surface being damaged by slight rubbing.

On the other hand, when using a fluorine-containing polymer as an ink-repellent layer, despite the low surface energy of the fluorine-containing polymer according to scientific measurements, when used for printing as a lithographic plate that does not require dampening water, the ink repellency remains low. Apart from so-called light printing for the purpose of printing a small number of copies, printing durability that can be used for heavy commercial printing cannot be achieved because of the poor adhesion between the fluorine-containing polymer and the support. This is a problem before the shortcomings.

The present inventors have studied various currently proposed waterless planographic material systems and researched methods to improve their shortcomings. Thickness of several μ or more
Although the layer thickness is 100μ or less, the present inventors believe that if the layer is firmly adhered to the underlying photosensitive resin layer, such a thickness is unnecessary and a few μ or less is sufficient. Based on this idea, in order to firmly adhere the silicone compound to the photosensitive resin layer,
It was discovered that a trivalent chromium complex salt of galvanic acid having a polyorganosiloxane residue as a silicone compound is extremely useful, and the present inventors have already proposed a unique lithographic printing plate that does not require dampening water. Furthermore, based on the same idea, the present inventors investigated fluorine-containing compounds with poor ink repellency, and found that, although this was completely unexpected, ink repellent layers of this type do not normally contain fluorine-containing compounds. Compared to a fluoropolymer layer, it not only has high abrasion resistance based on strong adhesion with the underlying layer, but also exhibits much stronger ink repellency, so it can be used not only for small print runs but also for heavy prints, without the need for dampening water. A planographic plate was obtained, and the present invention was completed.

That is, the present invention has a photosensitive layer on a support with or without a synthetic resin adhesive subbing layer, and furthermore, on the photosensitive layer, a monovalent or divalent compound whose residue is a fluorine-containing compound is provided. This is a lithographic printing plate that does not require dampening water and is made by laminating trivalent chromium complex salts of carboxylic acids with higher valences.

In the present invention, there are various monovalent or divalent or more carboxylic acids whose residues are composed of fluorine-containing compounds that can be used in producing the trivalent chromium complex salt. In particular, the "carpet-like" ink-repellent layer of the present invention, which is firmly bonded to the lower layer, exhibits overwhelmingly superior ink-repellency compared to the mere "bed-like" ink-repellent layer of the prior art. As a usable fluorine-containing compound structure, it becomes possible to reduce the content of fluorine, which is a factor in the ink-repellent structure, and the range of selection is further expanded. The fluorine content in monovalent or divalent carboxylic acid whose residue is a fluorine-containing compound is 39
It can be used if it is more than % by weight, but if it is less than that, it will have an unfavorable effect on ink repellency.

In the present invention, the fluorine-containing compound itself may be either linear or branched. In addition, the carboxylic acid group may be present at the chain end of the fluorine-containing compound, branched in the middle of the compound as a side chain, by a direct bond, or as a divalent group that bonds the fluorine-containing compound and the carboxylic acid group. By bridging by , those tied to the former can be used. An example of a monovalent or divalent or more carboxylic acid whose residue is a fluorine-containing compound used in the present invention is as follows.

1(i) A carboxylic acid attached to the end of a fluorinated alkyl group CF ₃ −(CF ₂ ) ₁₀ −COOH CF ₃ −(CF ₂ ) _o −COOH (ii) A carboxylic acid attached to the side chain of a fluorinated alkylene group is combined with The molecular weight of the fluorine-containing compound having a carboxylic acid group that can be used in the present invention can be determined from the simplest form such as CF ₃ -COOH. That is, it can be used from a molecular weight of around 100, but apart from special printing applications, it is preferable to have a molecular weight of 500 or more from the viewpoint of printing durability during practical printing.
Although there is no particular restriction on the upper limit of the molecular weight, a preferable upper limit is about 100,000 because of the ease of manufacturing the trivalent chromium complex salt. Of course, the photosensitive layer is treated in advance with a trivalent chromium complex salt of a fluorine-containing compound into which a functional group capable of chain extension and/or crosslinking reaction is introduced, and at the same time or subsequently the photosensitive layer is treated with a trivalent chromium complex salt that can react with the trivalent chromium complex salt. Extending the fluorine-containing component with a fluorine compound is included in the present invention.

Regarding the production of trivalent chromium complex salts of carboxylic acids, see US Patent Nos. 2544666, 2544667 and 2544668.
As detailed in the specification etc., the reaction between organic carboxylic acid and basic chromium() chloride causes
It is obtained by forming a Werner type complex salt containing a trivalent chromium atom. This complex salt is used in paper, fiber,
When applied to the surface of a substrate such as glass fiber or plastic film that generally has a hydroxyl group, a carboxyl group, an acid amide group, a sulfonic acid group, etc. in its molecular chain, the trivalent chromium complex strongly binds to the surface of the substrate.

The same holds true for the method for producing trivalent chromium complex salts and the bonding properties to the substrate surface for the monovalent, divalent or higher carboxylic acid whose residue is a fluorine-containing compound used in the present invention.

In carrying out the present invention, the support may be a synthetic resin film such as a polyester film,
A thin metal plate such as aluminum or iron plate, or a paper sheet is used. These surfaces may be subjected to surface treatments, i.e. mechanical processing for roughening, as required.
In some cases, chemical processing or electrical or electrochemical processing is performed, such as in the case of anodized aluminum sheets.

An adhesive subbing layer is usually applied over such a planar support. This subbing layer is a synthetic resin adhesive layer for ensuring the adhesion between the support and the photosensitive layer. This adhesive undercoat layer is applied during the plate-making process of the product of the present invention.
By removing the unexposed areas (or exposed areas depending on the type of photosensitive layer; the same applies hereinafter) of the photosensitive layer through development processing, the photosensitive layer becomes the first layer on the surface and forms a recessed surface that is receptive to printing ink. Since it is a part, it is selected based on two criteria: adhesiveness and ink receptivity.
Further, it is preferable that such an undercoat adhesive layer contains an ultraviolet absorber, a pigment, etc. so as to have an antihalation function. Needless to say, adhesion is controlled by the material and surface condition of the support, so sufficient adhesion strength is ensured by directly laminating the support and photosensitive layer, and the surface is removed by removing the photosensitive layer in unexposed areas. If the surface of the support appearing on the printhead has sufficient printing ink receptivity, the subbing adhesive layer is not necessary if the support has sufficient antihalation properties.

Furthermore, to explain the main points in implementing the present invention,
A thin photosensitive layer of several microns to 30 microns or less spread on a support is coated with a solution of the trivalent chromium complex of carboxylic acid whose residue is a fume-containing compound as described above. In some cases, after coating and before or after drying, excess unreacted complex may be removed by washing with a solvent for the complex.

After being applied, the solvent is dried, and at the same time,
Or separately, 3 carboxylic acids of fluorine-containing compounds
In order to strengthen the bond between the valent chromium complex salt and the photosensitive layer, heat curing is performed at a temperature of 50°C to 110°C for several minutes to several tens of minutes, and the hydroxyl groups, carboxyl groups, amide groups, and urethane groups on the surface of the photosensitive layer are cured. A strong bond based on a covalent bond is formed between a group, an amino group, etc. and a trivalent chromium atom. Since the ink-repellent layer of the present invention can achieve sufficient ink-repellency with an extremely thin layer of a fluorine-containing compound, the thickness of the finished ink-repellent layer is sufficient to be several angstroms to tens of thousands of angstroms.

The photosensitive materials forming the photosensitive layer used in the present invention include photopolymerizable, photocrosslinkable, and photosoluble (insoluble) photosensitive materials.
Photosensitive materials belonging to classifications such as chemical type can be mentioned. Photopolymerizable types include polyamide resin,
Ordinary letterpress printing using polyvinyl alcohol resin, poly-methyl methacrylate resin, polyurethane resin, cellulose derivative resin, polyvinylpyrrolidone resin, etc. as a binder and a photopolymerizable Japanese ethylenic double bond as a crosslinking agent. This is a photosensitive resin composition for printing. Examples of photo-soluble (insoluble) types include compositions for negative or positive PS offset plates (lithography), such as diazo resins made by condensing para-aminodiphenylamine and formalin, and combinations of quinonediazide and novolac resins. In the photo-crosslinking type, combinations of various resins and azide compounds,
Examples include photosensitive compositions containing photodimerizable functional groups such as vinyl cinnamate groups.

As described above, the waterless lithographic printing plate material of the present invention has a structure including a support, an undercoating adhesive layer if necessary, a photosensitive layer, and a monovalent or divalent or more monovalent or divalent or more fluorine-containing compound, the residue of which is a fluorine-containing compound. A trivalent chromium complex salt layer of carboxylic acid, a cover layer or a cover film when necessary, and is manufactured by repeating coating in layers from the lower layer to the upper layer.

When using the plate-making process for the product of the present invention, if there is a cover film, a negative or positive film is adhered thereon depending on the characteristics of the photosensitive layer on which the image pattern is drawn, and then it is exposed to ultraviolet rays. Therefore, when exposed to light, the exposed portions of the photosensitive layer are hardened and made insolubilized by a photoreaction (depending on the type, they become solubilized), and the unexposed portions do not undergo any reaction.
Next, when the photosensitive layer is treated with a developer for elution and development, the uncured portions of the photosensitive layer are eluted. At this time, the trivalent chromium complex salt of the carboxylic acid of the fluorine-containing compound in the unexposed area is also washed out into the developer together with the photosensitive resin layer in the unexposed area, and in the end, only the subbing adhesive layer is left in the unexposed area. It remains and has no ink repellency. On the other hand, in the exposed areas, the photosensitive resin layer remains, and on top of it there is a fluorine-containing compound layer firmly fixed through covalent bonds and coordinate bonds based on trivalent chromium atoms, which exhibits ink repellency. As a result, a lithographic printing plate material that does not require dampening water is formed.

With the above configuration, a lithographic printing plate that does not require dampening water and has printing durability and resolution unparalleled by conventional technology can be obtained, but these excellent properties are due to the strong bond with the underlying photosensitive layer. This was realized for the first time by the structure of the present invention, which has a very thin "carpet-like" ink-repellent layer.

The present invention will be specifically explained below using examples.

Reference Example 1 Preparation of fluorine-containing compound carboxylic acid chromium () complex salt solution Synthesis agent that induces a monovalent, divalent or higher carboxylic acid of a fluorine-containing compound, which is one of the constituent elements of the present invention, into its chromium () complex salt The following is an example.

2.7 g of 36% hydrochloric acid in a 200 ml three-necked flask equipped with a stirrer, reflux condenser, and dropping funnel.
and 47.3 g of isopropanol were added and immersed in a heating bath. While maintaining the heating bath temperature between 60℃ and 80℃, add 16.8g of chromium trioxide and 36% hydrochloric acid from the dropping funnel.
33.4 g of the mixed solution was gradually added dropwise over about 1 hour. After the dripping is complete, keep the temperature of the liquid at 78℃.
The mixture was slowly heated to reflux and maintained for 3 hours. The inner solution was blackish brown. After cooling, 2.5 g of 36% hydrochloric acid was added to adjust the chlorine/chromium equivalent ratio to 2/1.
At this time, the product exhibited a dark green color, and it was found that basic chromium () chloride Cr(OH)Cl ₂ was produced.

Next, 12.3 g of a monovalent carboxylic acid of a fluorine-containing compound having the following structure with a molecular weight of 614, 30.9 g of isopropanol, and the previously prepared and stored basic chloride source solution CF ₃ (CF ₂ ) ₁₀ -COOH rom() A total of 11.9 g of the three components was heated and refluxed for about 2 hours in a three-necked flask equipped with a reflux condenser to obtain the fluorine-containing compound carboxylic acid chromium() complex salt as a transparent green liquid. . Hereinafter, this solution will be abbreviated as a fluorine-based reagent stock solution. In the same manner, fluorine-containing carboxylic acids having molecular weights of about 2,000 and 5,000, respectively, were prepared.

Example 1 Toyobo Vylon 20S resin liquid 233 was applied as an adhesive layer and an anti-halation layer on a 150μ aluminum plate.
part, Coronate L 40 parts, triethylenediamine 0.5 parts
A solution containing 3,261 parts of Tinuvin was added to a thickness of 10 μm.
The film was cured for 3 minutes at 120°C. In addition, Toyobo Printite EF type resin composition (this resin composition uses a water-soluble copolymer nylon as a binder, an acrylic acid monomer as a crosslinking agent, and also contains a small amount of a photoinitiator, etc.) ) dissolved in methanol was coated and dried to a thickness of 5 μm. A fluorine-based compound prepared from the fluorine-containing compound carboxylic acid having a molecular weight of 614 in Reference Example 1 was diluted 8 times with isopropanol, coated and dried on the photosensitive resin layer thus prepared. Thereafter, it was cured at 60°C for 15 minutes. A positive film was layered on the plate material prepared in this way, and after vacuum adhesion, it was exposed for 2 minutes from a distance of 60 cm from a 3K.W. I did drying.

In the completed plate, the photosensitive layer in the exposed areas is photocured and becomes insoluble, and the fluorine-based compound remains attached to the surface layer and exhibits ink repellency, whereas the unexposed areas are washed away during development. It was found that the adhesive layer coated on the aluminum plate was exposed on the surface layer, and this area had an affinity for ink and that the ink would adhere to it. Using this plate, you can use waterless lithographic ink (Dainippon Ink & Chemicals Co., Ltd.) without using dampening water.
When printing was carried out with an offset printing machine using the product), sharp printed matter was obtained.

Example 2 A commercially available negative PS offset plate (SGN- manufactured by Fuji Photo Film Co., Ltd.) was coated with fluorine-containing compound carboxylic acid having a molecular weight of 2000 by the method of Reference Example 1.
The fluorine-based compound obtained by converting it into a valent chromium complex was diluted 8 times with isopropanol, and after coating and drying, curing was performed at 60° C. for 15 minutes. A positive film was placed on top of this plate, and after vacuum contact, exposure was carried out for 2 minutes using a chemical lamp from a distance of 10 cm.

Next, the plate was immersed in a 1:1 mixture of PS plate developer (DN-3C) and water, developed while loosely wiping with absorbent cotton, and then washed with water and dried. This plate has a fluorine-based compound attached to the exposed areas and exhibits ink repellency, while the unexposed areas are washed away during development and the aluminum parts are exposed on the surface, giving it an affinity for ink. show. When this plate was used to print using waterless lithographic ink (manufactured by Dainippon Ink & Chemicals Co., Ltd.) without dampening water and an offset printing machine, sharp printed matter was obtained. Ta.

Example 3 A fluorine-based product was obtained by converting a commercially available positive PS offset plate (Fuji Photo Film Co., Ltd. product SGP-K) into a trivalent chromium complex salt of a fluorine-containing compound carboxylic acid having a molecular weight of 5000 using the method of Reference Example 1. After diluting the compound 8 times with isopropanol, coating and drying,
After stacking the negative films and adhering them in vacuum, exposure was carried out for 3 minutes from a distance of 10 cm using a chemical lamp. Next, it was immersed in a solution containing this PS plate developer (DP-3) and water at a ratio of 1:1, developed while loosely using absorbent cotton, and then washed with water and dried.

The exposed areas of this plate were dissolved and removed during development, leaving the aluminum surface exposed, whereas the unexposed areas remained with a fluorine-based compound attached to their surfaces, and were found to exhibit ink repellency.

Claims (1)

[Claims] 1 A photosensitive layer is provided on a support with or without an adhesive subbing layer, and a trivalent monovalent or divalent or more carboxylic acid whose residue is a fluorine-containing compound is further provided on the photosensitive layer. A lithographic printing plate that does not require dampening water and is made by laminating chromium complex salts.