JPH0730273B2 - Waterless planographic printing plate image forming liquid - Google Patents

Description

The present invention relates to a liquid for forming an image area on a waterless lithographic printing plate. More specifically, the present invention relates to a liquid for forming an image portion on a waterless planographic printing plate by means of an ink jet method, various printers for recording with a pen, direct writing such as handwriting or a typewriter.

[Prior Art] In the present invention, the target waterless lithographic printing does not require a dampening liquid for repelling ink at the time of printing in a non-image area, and can be simply printed with only printing ink. Is the law. There are roughly two types of plate materials for this printing.
One is a plate material that has a photosensitive resin layer and is exposed through a negative or positive film to form an image portion, and the other is a method of directly forming an image by electrophotography or handwriting, that is, It is a direct drawing plate material by filmless direct plate making. The present invention mainly relates to an image forming solution for direct drawing plate making for the latter plate material.

An electrophotographic method is generally used as a method for forming an image on a non-photosensitive waterless planographic material, and in that case, an image portion is formed by solid toner fine particles. This method is an extremely effective method when a printing block is provided. However, since this method is a recording of a given image, that is, the anaguro information, there is no choice but to be restricted in its use. It is generally not possible to make a plate by directly outputting digital information stored in a computer or the like to a waterless planographic material. For plate making, it was necessary to output digital information as a hard copy once, and then use this as a master copy for plate making by electrophotography or the like. It is unavoidable not only that it is economically and time-consuming to make an image once output through the plate making machine again, but also it becomes inferior in terms of image quality.

For the direct recording of digital information on a waterless direct drawing lithographic material, it is preferable to use a liquid such as ink from the viewpoint of the convenience of the apparatus, the recording speed and the quality of the recorded image. There are few proposals for liquids suitable for. As a conventional proposal, a method of adhering a photosensitive polymer imagewise by an inkjet method and then irradiating light to cure the photosensitive polymer to obtain a waterless printing plate (JP-A-51-84303) There is. The present inventor has also proposed a solution comprising a hydroxyl group-containing polymer, an organosiloxane polymer having a plurality of Si-H groups, and an organometallic catalyst (JP-A-60-196346).

[Problems to be Solved by the Invention] The present invention relates to a liquid for expanding an image forming method on a waterless planographic material to record digital information, perform platemaking, and perform direct platemaking such as handwriting. More specifically, it relates to a liquid which forms an image on a waterless planographic printing plate and the formed image portion exhibits high durability in printing.

A waterless planographic material generally has an ink repellent layer such as silicone rubber provided on the surface of a substrate, and an image is formed by adhering a solid image member thereon. Adhesion becomes a big problem. Furthermore, when using liquid imaging materials,
The wettability of the liquid with respect to the plate surface also becomes a problem.

In the case of image formation by inkjet printing,
The ink used in conventional inkjet printers is generally an aqueous solution in which a dye is dissolved, and the surface on which an image is formed is usually fine paper, art paper, coated paper, or the like. In that case, the wettability of the ink with respect to the paper, the adhesive force, etc. do not matter. However, since the waterless planographic material targeted in the present invention repels not only printing ink but also many liquids including water, the ink is repelled on the plate surface by a general jet ink, and a good image can be formed. Can not. Further, unlike a simple image forming sheet, since it is used as a printing plate for printing a large number of sheets, the printing durability of the ink image portion, that is, the adhesion to the plate surface becomes a problem. Even if an ordinary jet ink can form an image, the adhesion of the image member to the plate surface is extremely low, so that 10 sheets cannot be printed.

Although the above-mentioned photosensitive polymer proposed in JP-A-51-84303 has insufficient adhesiveness, it is insufficient, and the operation is complicated because light irradiation is required. There are also problems with storage stability. In addition, JP-A-60-19
Although the solution disclosed in 6346 is excellent in terms of adhesiveness in the image area, it has a problem in storage stability and contains a printing ink repellent silicone component. The meat tends to be inferior.

An object of the present invention is to solve the problems of the conventional techniques described above and to provide an image forming liquid which is satisfactory in all aspects.

[Means for Solving Problems] The present invention relates to an image forming liquid for a waterless lithographic printing plate, which contains the following components as essential components.

(A) Hydroxyl group-containing polymer having a molecular weight of 5,000 to 100,000 (b) Complex compound of a metal having a valence of 3 or more (c) A solvent component containing 40% by weight or more of an organic solvent having a surface tension of 22 dyne / cm or less at 20 ° C. .

The component (a) used in the present invention is a hydroxyl group-containing polymer having a molecular weight of 5,000 to 100,000 and having a side chain of 1
A linear soluble polymer having a secondary or secondary alcoholic hydroxyl group can be mentioned. By forming a chemical bond or a hydrogen bond between the hydroxyl group of the polymer in the image forming liquid and the terminal group of the silicone rubber which is the surface layer of the waterless planographic printing plate material (the terminal group based on the crosslinking agent of the silicone rubber), The image forming liquid and the silicone rubber layer are firmly adhered to each other. Therefore, the ink image portion (the portion where the image forming liquid adheres to the silicone rubber layer) does not drop even when printing a large number of sheets and can exhibit high printing durability. Specific examples of such a polymer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and glycerol mono (meth) acrylate. Copolymers containing hydroxyl group-containing (meth) acrylates such as acrylates as copolymerization components, polyvinyl alcohol or its derivatives (including residual hydroxyl groups), such as polyvinyl butyral, polyvinyl formal, partially saponified polyvinyl acetate, etc. Examples thereof include an epoxy resin having a hydroxyl group inside or a hydrolyzate thereof. In the above-mentioned copolymer containing a hydroxyl group-containing (meth) acrylate as one component, examples of other copolymers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, ( 2-ethylhexyl (meth) allylate,
Alkyl (meth) acrylates such as lauryl (meth) acrylate, unsaturated carboxylic acids such as (meth) acrylic acid and itaconic acid, (meth) acrylamide, styrene and the like are used.

These hydroxyl group-containing polymers may be used alone or in combination of two or more different kinds. It can also be used as a mixture with another polymer not containing a hydroxyl group.

The molecular weight of these hydroxyl group-containing polymers is 5,000 to 100,000.
Is. If the molecular weight exceeds 100,000, the coating film (the ink image part of the waterless lithographic printing plate) is likely to come off because of adverse effects such as decreased solubility, increased solution clay, and decreased adhesiveness, and high printing durability. Can't get Also, the molecular weight is 5,00
If it is less than 0, the toughness of the coating film is inferior and the printing durability is also inferior.

Next, the complex compound of a metal having a valence of 3 or more used as the component (b) of the present invention is an essential component for adhering the image portion to the surface of the plate material made of silicone rubber. Examples of metals that can be used include Al, Sn, Fe, Co, Mn, Ni, Ti and C.
r, V, etc. Specific examples of complex compounds or salts of these metals include aluminum acetylacetonate, iron (III) acetylacetonate, cobalt acetylacetonate, aluminum ethylacetoacetate, cobalt naphthenate, zinc naphthenate,
Examples thereof include stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, and the like. Among these, particularly preferable are complex compounds of metals having a valence of 3 or more, such as iron (III) acetylacetonate and aluminum acetylacetonate. One of these compounds may be used alone, or two or more different compounds may be mixed and used. The amount of these metal compounds used is about 0.1 to 100 parts, and more preferably 0.5 to 50 parts, relative to 100 parts by weight of the hydroxyl group-containing polymer as the component (a).

The solvent component of (c) has a surface tension of 22 dyne / cm at 20 ° C.
It is important to contain 40% by weight or more of the following organic solvents. The critical surface tension of silicone polymer is 20-22 dyne / cm
This is because the surface tension of the liquid needs to be a value equal to or less than that in order to wet the surface without being repelled by the liquid. By using such a solvent component, good coatability is exhibited even on the surface of a waterless planographic printing plate material having a silicone rubber as a surface layer. The solvent is not particularly limited as long as it dissolves the components (a) and (b) and does not cause a chemical reaction with these components at room temperature, and includes alcohols, ethers, ketones, carvone. Various substances such as acid esters, fatty acids, aromatic or alicyclic hydrocarbons can be used alone or in admixture of two or more.

Examples of such low surface tension solvents include paraffinic or isoparaffinic hydrocarbons, tert-butyl alcohol, ethyl ether, acetal, isopropyl alcohol and the like. In general, a solvent system is mainly used in which these low surface tension solvents are mainly used, and other solubilities thereof are appropriately mixed according to purposes such as polymer solubility and adjustment of solution evaporation rate. In selecting the polymer as the component (a), it is necessary to consider the solubility in a solvent system mainly containing such a low surface tension solvent.

In addition to the above-mentioned essential components, various substances can be added to the image forming liquid of the present invention, if necessary, but addition of a colorant is particularly preferable. Although the addition of a coloring agent is not essential, from the viewpoint of plate inspection property, it is preferable that the image forming printing plate is appropriately colored to form an easily visible image portion, and therefore, a soluble dye or a stable dispersion is used. A pigment such as carbon or alkali blue toner is appropriately added. When a pigment is used, a dispersant such as a suitable surfactant may be further added to improve the dispersibility of the pigment.

The concentration of solids in the liquid varies depending on the image forming method, the type of polymer used and the degree of polymerization, but is preferably 1 to 30% by weight. Although the permissible range is wide in the case of handwriting, the inkjet method requires a solution viscosity of about 50 centipoise or less, so the polymer concentration is about 1 to 20% by weight.

Examples of the image forming method to which the liquid of the present invention is applied include an inkjet method, various printers and recorders for recording with a pen, and handwriting.

The solution image on the image-formed plate material is strongly adhered to the plate surface by heat treatment after the solvent is removed or at the same time when the solvent is removed. The optimum temperature of the heat treatment varies depending on the composition of the image forming liquid, but is generally in the range of 50 ° C to 300 ° C, more preferably 100 ° C to 250 ° C.
Is the range. The time required for the heat treatment varies depending on the composition of the liquid or plate material, the heating method, the treatment temperature, etc., but is usually in the range of 1 second to 10 minutes. The heat treatment method may be any of hot air, radiant rays, hot rolls, etc., and two or more of these may be used in combination.

The waterless planographic printing plate material used in the present invention has a silicone rubber layer having a printing ink repellent property on the surface. Preferred as such a silicone rubber layer is one containing a group or atom that contributes to adhesion with other substances in the molecule, and among these, particularly preferred is a high molecular weight organoorganic group previously proposed by the present inventors. This is a silicone composition using hydrogen polysiloxane as a cross-linking agent (Japanese Patent Application No. 61-6902).

The image forming liquid of the present invention gives a coating film having remarkably good adhesiveness and durability to a direct drawing plate material for waterless lithographic printing having such a silicone rubber coating layer, and a printing plate excellent in printing durability. give.

In general, the mechanism by which the composition of the present invention strongly adheres to the difficult-to-adhere silicone surface is not clear, but the hydroxyl groups in the polymer of the image forming liquid component and the functional groups such as silanol groups present in the silicone, It is presumed that this is due to bonding through a coordinate bond via a metal atom.

[Examples] Examples of the present invention will be described below, but the present invention is not limited to the scope of these examples.

All "parts" used in the examples are parts by weight.

Manufacture of waterless direct drawing lithographic material The waterless lithographic printing direct drawing material used in the following examples was a paper substrate (“Mirror Coated Paper Gold”, manufactured by Kanzaki Paper Co., Ltd., weighing 127.9 g / m ² ). ) Is coated with a silicone coating solution having the following composition using a wire bar coater (the amount after drying is 4 g / m ² ) and placed in a hot air dryer at 160 ° C for 1 minute at 160 ° C. It is manufactured by performing heat treatment.

Both ends silanol group polydimethylsiloxane (number average molecular weight about 25,000) 70 parts One end silanol group polydimethylsiloxane (number average molecular weight about 30,000) 30 parts Methyl hydrogen polysiloxane (weight average molecular weight 64,000) 20 parts Dibutyltin diacetate 2 Part Acetic acid 20 parts "Isopa E" (manufactured by Esso Chemical Co., Ltd.) 450 parts Example 1 Polyvinyl butyral # 2000-L (manufactured by Denka Co., molecular weight about 15,000) 5 parts tert-butyl alcohol (at 20 ° C) Surface tension (20.7 dyne / cm) 80 parts, dissolved by heating in a mixed solution of 20 parts isopropyl alcohol, 0.5 parts iron (III) acetylacetonate, "Sumiplast Blue OA" (oil-soluble dye, manufactured by Sumitomo Chemical Co., Ltd.) ) 0.3 part was added, stirred and dissolved, and then the filter paper was melted and passed through to obtain an image forming liquid.

An image was drawn on the plate material by hand using the above liquid. Handwriting was performed using a calligraphy brush or a drafting pen. After image formation, heat treatment was carried out at 160 ° C. for 1 minute in an electrothermal dryer to obtain a printing plate.

The printing durability of the obtained printing plate was tested using a two-cylinder type direct printing press (prototype). The force applied to the printing surface of the two-cylinder type direct printing machine is much stronger than that of the three-cylinder type offset printing machine, and the printing conditions are extremely severe for the printing plate. The ink used was designed for waterless printing.

A clear printed image can be obtained, and the image part is skipped (dropped) at 2,000
After printing 0 sheets, nothing happened.

Example 2 In Example 1, dibutyltin diacetate was used instead of iron (III) acetylacetonate as a component of the image forming liquid.
The same procedure as in Example 1 was carried out except that 0.5 part was used. about
After printing 1,000 sheets, some jumps were seen at minute spots, but solid areas did not jump until more than 2,000 sheets.

Example 3 Polyvinyl butyral # 3000-K (manufactured by Denka Corp., molecular weight about 40,000) 3 parts, tert-butyl alcohol (surface tension 20.7 dyne / cm at 20 ° C.) 50 parts, n-butyl ether 20 parts, lauric acid 20 parts methyl, 10 lauryl alcohol
Then, 0.5 part of iron (III) acetylacetonate and 0.3 part of "Sumiplast Blue OA" were added and dissolved, and the mixture was filtered using a filter paper to obtain an image forming liquid.

An image was formed on the plate material by an inkjet device using the obtained liquid. The device is an on-demand type equipped with a glass nozzle having a diameter of 100 μm, and ink (image forming liquid) is ejected by a pressure pulse and flies toward the plate surface. The plate is held on a rotating cylinder and a 6K / mm image is obtained with a pulse of 2KHz. Using such an apparatus, a test pattern image consisting of minute dots, fine lines, characters, solids, etc. was formed on the plate material and heat-treated at 160 ° C. for 1 minute to obtain a printing plate.

The printing durability of the obtained printing plate was tested by a direct printing press in the same manner as in Example 1. No jumps were seen at all over the number of printed sheets of 2,000 or more, even for minute dots, fine lines, and character portions.

[Effects of the Invention] As described above, an image having excellent durability can be formed on a waterless planographic printing plate by the image forming liquid of the present invention. It has become possible to obtain a waterless planographic printing plate having excellent printing durability.

Claims (1)

[Claims] 1. A liquid for image formation of a waterless planographic printing plate, which contains the following components as essential components. (A) Hydroxyl group-containing polymer having a molecular weight of 5,000 to 100,000 (b) Complex compound of metal having a valence of 3 or more (c) Organic solvent containing 40% by weight or more of an organic solvent having a surface tension of 22 dyne / cm or less at 20 ° C .