JP3013498B2 - Waterless lithographic printing plate developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer for a waterless lithographic printing plate, and more particularly to an improvement of a waterless lithographic printing plate having a photocurable layer and a silicone rubber layer laminated on a base plate. It is related to the developed developer.

[0002]

2. Description of the Related Art Various waterless lithographic printing plates having a silicone rubber layer as an ink repellent layer have already been proposed. Above all, JP-B-54-26923 or JP-A-50-5
A waterless lithographic printing plate in which a photopolymerizable adhesive layer and a silicone rubber layer are laminated on a substrate proposed in, for example, Japanese Patent No. 0102, and a photocurable A waterless planographic printing plate in which a layer and a silicone rubber layer are laminated enables practical printing without using fountain solution.

[0003] A waterless planographic printing plate is usually made through the following exposure and development steps. First, the lithographic printing plate precursor is exposed to actinic rays through a vacuum-contacted positive film. The printing original plate after the exposure is immersed in a paraffinic hydrocarbon or a developing solution containing the same as a main component.
As a result, the silicone rubber layer in the unexposed area is strongly swollen by the developing solution, and wrinkles are generated. When the printing plate surface is lightly rubbed with a soft pad such as a gauze in this state, only the swollen unexposed portion of the silicone rubber layer is peeled off, exposing the lower uncured photocurable layer. This portion becomes the ink-imprinting image portion. On the other hand, although the silicone rubber layer in the exposed portion slightly swells with the developing solution, it is strongly adhered to the photocured photocurable layer, so that it is not eroded by the developing pad and remains on the plate surface. Is formed into a waterless planographic printing plate by forming an ink-repellent non-image area. The lithographic printing plate without water obtained through such a plate-making process has sharp silicone dots in the silicone rubber layer and can provide sharp halftone dots. The silicone rubber layer is also used as the part where the silicone rubber layer should originally be removed and removed.
The rubber layer remains, resulting in a printing plate having poor reproducibility of fine halftone dots. If the plate surface is rubbed too strongly during development, the silicone rubber layer to be left on the printing plate surface as a non-image area is damaged. As a result, there is a problem in that the printed matter, which is the final product, becomes stained or defective, and a printing plate having excellent printing characteristics cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have made intensive studies on measures for improving the disadvantages of the prior art in view of the disadvantages of the prior art. As a result, the development of a waterless lithographic printing plate having a silicone rubber layer as an ink repellent layer has been developed. By using diester as the liquid, it was found that the developability was remarkably improved, and it was possible to easily reproduce fine halftone dots, and the present invention described below was achieved.

[0005]

That is, the present invention relates to a waterless lithographic printing plate characterized by containing at least 0.5% by weight of at least one diester having a structure represented by the general formula (1). It is a developer.

R ₁ OOC—X—COOR ₂ (1) ( where X is a divalent aliphatic hydrocarbon having 4 to 15 carbon atoms )
In the case of element or an alicyclic hydrocarbon having 5 to 15 carbon atoms, R
₁ , R ₂ is an aliphatic hydrocarbon having 1 to 15 carbon atoms, and X is
In the case of an aromatic hydrocarbon having 6 to 15 carbon atoms, R ₁ and R ₂ are
It is an aliphatic hydrocarbon having 4 to 15 carbon atoms. R _1, R ₂ Waso
Each may be the same or different
No. The diester used in the present invention has a structure represented by the general formula (1), wherein the formula has 4 carbon atoms.
~ 15 divalent aliphatic hydrocarbon or 5 ~ 15 carbon atoms
In the case of an alicyclic hydrocarbon, R ₁ and R ₂ have 1 to 15 carbon atoms.
X is an aromatic carbon having 6 to 15 carbon atoms, which is an aliphatic hydrocarbon.
In the case of hydride, R ₁ and R ₂ are aliphatic carbons having 4 to 15 carbon atoms.
Hydrogen. R ₁ and R ₂ may be the same.
It may be different. If the aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon, and R ₁ and R ₂ each have more than 15 carbon atoms, and the diester is contained in the developer, the interface between the photocurable layer and the silicone rubber layer The effect of lowering the adhesive strength is small, and it is difficult to reproduce fine halftone dots, which is not preferable. Such diester is used in an amount of 0.1% of the total amount of the developing solution.
It is important that it be contained in the range of 5 to 100% by weight, preferably 1.0 to 100% by weight.

[0007] Specific examples of the diester used in the present invention include, but are not limited to, the following.

[0008] Dimethyl adipate, dibutyl adipate, dihexyl adipate, dioctyl adipate, didodecyl adipate, dimethyl ethyl succinate, dibutyl ethyl succinate, dihexyl ethyl succinate, dioctyl ethyl succinate, didodecyl ethyl succinate, dimethyl pimerate, dibutyl pimerate , Dihexyl pimerate, dioctyl pimerate, didodecyl pimerate, dimethyl suberate, dibutyl suberate, dihexyl suberate, dioctyl suberate, didodecyl suberate, dimethyl azelate, dibutyl azelate, dihexyl azelate, dihexyl azelate, azelaine Didodecyl acid, dimethyl sebacate, dibutyl sebacate, dihexyl sebacate, dioctyl sebacate, sebacic acid Dodecyl, 1,10-decane dicarboxylic acid dimethyl, 1,10-decane dicarboxylic acid dibutyl 1,10 decanedicarboxylic acid dihexyl,
Dioctyl 1,10-decanedicarboxylate, 1,10-
Didodecyl decanedicarboxylate, cyclohexane-1,
Dimethyl 2-dicarboxylate, cyclohexane-1,2-
Dibutyl dicarboxylate, dihexyl cyclohexane-1,2-dicarboxylate, dioctyl cyclohexane-1,2-dicarboxylate, didodecyl cyclohexane-1,2-dicarboxylate, dimethyl cyclohexane-1,3-dicarboxylate, cyclohexane-1,3- Dibutyl dicarboxylate, dihexyl cyclohexane-1,3-dicarboxylate, dioctyl cyclohexane-1,3-dicarboxylate, didodecyl cyclohexane-1,3-dicarboxylate, dimethyl cyclohexane-1,4-dicarboxylate,
Dibutyl cyclohexane-1,4-dicarboxylate, dihexyl cyclohexane-1,4-dicarboxylate, dioctyl cyclohexane-1,4-dicarboxylate, didodecyl cyclohexane-1,4-dicarboxylate, dibutyl phthalate, dihexyl phthalate, phthalic acid Dioctyl, didodecyl phthalate, dibutyl terephthalate, dihexyl terephthalate, dioctyl terephthalate, didodecyl terephthalate, dibutyl phenylmalonate, dihexyl phenylmalonate, dioctyl phenylmalonate, didodecyl phenylmalonate, dibutyl phenylmalonate, dibutyl phenylsuccinate, phenylsuccinate Dihexyl, dioctyl phenylsuccinate, didodecyl phenylsuccinate and the like.

Of the above, R ₁ and R ₂ have 1 to 1 carbon atoms.
Diesters that are two aliphatic hydrocarbons are particularly useful.

As the developing solution of the present invention, a solution obtained by adding another solvent to a diester can be used. Such solvents include paraffinic hydrocarbons readily available from petroleum fractionation products or those containing the same as main components, refined paraffinic hydrocarbons such as pentane, hexane, heptane, and octane, water, and alcohols. , Esters, polyethylene glycols and derivatives thereof, polypropylene glycols and derivatives thereof, ketones, ethers, aromatic hydrocarbons, halogenated hydrocarbons and the like. Among them, polyethylene glycols and derivatives thereof, and polypropylene glycols and derivatives thereof are particularly effective.

The waterless lithographic printing plate to which the developer of the present invention can be conveniently applied is a lithographic printing plate having a silicone rubber layer as an ink repellent layer, and in particular, a photocurable layer and a silicone rubber layer on a substrate. Is a lithographic printing plate without water.

The substrate of the lithographic printing plate must have flexibility that can be set in a normal lithographic printing press and can withstand the load applied during printing. A typical substrate is
And metal plates such as paper, aluminum and steel or plastic films such as polyethylene terephthalate.

The photocurable layer is uniformly applied to the substrate, and if it is in close contact with the substrate, the thickness of the layer is arbitrary, but is preferably 100 μm or less, and more preferably 50 μm or less. Useful. If necessary, to improve the adhesion between the photocurable layer and the substrate or to prevent halation, an anchor coat is provided between the substrate and the photocurable layer.
It is also useful to make a layer.

The photocurable layer used in the present invention includes:
Examples include a photopolymerizable layer and a photocrosslinkable layer.

The photopolymerizable adhesive layer used in the present invention includes, for example, those having the following compositions. (1) Photopolymerizable unsaturated monomer or oligomer having a boiling point of 100 ° C or higher: 1.0 to 99.9 parts by weight (2) Photosensitizer: 0.1 to 20.0 parts by weight (3) Thermal polymerization inhibitor: 0.01 to 10.0 parts by weight ( 4) Filler for maintaining the form of the photopolymerizable layer (polymer or inorganic powder) 0.01 to 95.0 parts by weight A typical example of the photopolymerizable unsaturated monomer or oligomer is a monovalent monovalent having 30 or less carbon atoms. Alcohol or 1
Acrylic ester or methacrylic ester having a boiling point of 100 ° C. or higher derived from a divalent amine (hereinafter, these are abbreviated as (meth) acrylic esters. In the following description, (meth) □□□ is the same as Abbreviation for □□□ or meta □□□) or (meth) acrylamide, polyhydric alcohol having 30 or less carbon atoms or (meth) having a boiling point of 100 ° C or more derived from polyvalent amine. Acrylic esters, (meth) acrylamides, addition products of amines with glycidyl (meth) acrylate, and the like can be mentioned.

Representative examples of the photosensitizer include benzophenone, thioxanthone, Michler's ketone, benzoin methyl ether, dibenzyl disulphide, and uranyl nitrate. Typical examples of the thermal polymerization inhibitor include: Hydroquinone, phenothiazine and the like can be mentioned. Further, as the filler, polymers such as poly (meth) acrylate, polyurethane, polyamide and polyester, and inorganic powders such as colloidal silica and calcium carbonate are effective.

The photo-crosslinkable layer used in the present invention includes the following. (1) A photosensitive layer containing a photodimerizable photosensitive resin such as polyvinyl cinnamate. (2) A photosensitive layer comprising a combination of a monomer, oligomer or polymer having an epoxy group and a diazonium salt. When exposed to light, a Lewis acid is generated by photolysis of the diazonium salt, and the epoxy group undergoes cationic polymerization to crosslink. As the diazonium salt, for example, 2,5-diethoxy-4- (P-toluylthio) benzenediazonium hexafluorophosphate is used. (3) A photosensitive layer comprising a combination of a monomer, oligomer or polymer having an allyl group and a monomer, oligomer or polymer having a thiol group. When exposed to light, a thiol group is added to an allyl group to crosslink. (4) diazonium salts, such as condensates of P-diazodiphenylamine and formaldehyde. (5) A photosensitive layer mainly containing an azide compound and a cyclized rubber.

The silicone rubber layer of the present invention has a thickness of 0.5 to 50 μm, preferably 0.5 to 5 μm, and has transparency through which ultraviolet rays can pass. Useful silicone rubbers are those containing a linear diorganopolysiloxane (preferably dimethylpolysiloxane) having a molecular weight of 1,000 to 100,000, which is crosslinked by condensation of terminal groups, and to which a crosslinking agent and a catalyst are added if necessary. It is. The silicone rubber layer has ink repellency, and its surface is somewhat sticky, and is apt to adhere to dust and the like, so that problems such as difficulty in sufficiently adhering the positive film in the exposure step are likely to occur. A thin transparent protective film can be attached to the surface of the silicone rubber layer. This protective film also plays a role in suppressing the penetration of oxygen in the air into the photocurable layer and promoting photocuring of the photocurable layer. As described above, the protective film is useful in the exposure step, but is naturally removed by peeling or dissolving in the development step, and is unnecessary in the printing step.
Useful protective films are transparent enough to transmit UV light,
It has a thickness of 0 μm or less, preferably 10 μm or less, and representative examples thereof include the following plastic films. Polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol polyethylene terephthalate, cellophane, etc.

A positive film is vacuum-contacted to the lithographic printing plate precursor thus constituted using a conventional lithographic vacuum printing frame, and an actinic ray is irradiated through the film. When a protective film is present, after removing the protective film, the plate surface is gently rubbed with a soft pad such as a gauze or a non-woven fabric using the developing solution of the present invention, thereby substantially removing the silicon in the image area. Only the rubber layer can be peeled off to expose the photocurable layer in the image area. If necessary,
The image area is stained according to the method described in JP-A-54-103103. After the plate surface is immersed in the developing solution or the like, the plate surface is rubbed and then washed with another solvent, preferably water or a solvent containing water as a main component, thereby substantially rubbing the plate surface. It is also possible to adopt a method in which only the silicone rubber layer at the line portion is peeled off to expose the photocurable layer at the image portion. At this time, by adding a dye to the washing solvent,
It is also possible to dye the image area.

By using the developing solution of the present invention, a printing plate having good fine dot reproducibility and less scratches and defects can be obtained in a shorter developing time than before.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Examples 1 to 4 and Comparative Examples 1 and 2 A 4 micron thick photopolymerizable layer having the following composition was provided on an aluminum substrate. (a) 56 parts by weight of a polyurethane of a polyester polyol comprising adipic acid, hexane-1,6 diol and 2,2-dimethylpropane-1,3-diol and isophorone diisocyanate (b) 40 parts by weight of a 4 mol / 1 mol addition reaction product of glycidyl methacrylate and xylylenediamine (c) 4 parts by weight of Michler's ketone Then, on this photopolymerizable adhesive layer, 10 parts of a silicone having the following composition was added. % N-hexane diluent was applied and dried in hot air at 50 ° C. to provide a 3 μm thick silicone rubber layer. (a) 100 parts by weight of dimethylpolysiloxane (molecular weight: about 80,000) (b) 5 parts by weight of ethyltriacetoxysilane (c) 0.2 parts by weight of dibutyltin acetate A 10 micron thick polyethylene terephthalate film is added to the plate prepared as described above. "Lumilar" (Toray Industries, Inc.)
Was used as a protective film to obtain a lithographic printing plate precursor.

A positive film having a dot area ratio gradually changed (200 lines, 2% to 98%) was adhered to the lithographic printing plate precursor, and a 3 kw ultra-high pressure mercury lamp (manufactured by Oak Manufacturing Co., Ltd.) was used for 1 m. Exposure was for 90 seconds from a distance.

The laminated protective film was removed from the exposed plate, and each exposed plate was developed using a developer as shown in Table 1 to obtain a lithographic printing plate without water. The time required for the development of the printing plate obtained with these developers and the results of the dot reproduction range of the printing plate are shown in the attached table.

Example 1 containing a diester of general formula (1)
Using the developing solutions No. to No. 4, only the silicone rubber layer in the image area can be peeled off without substantially dissolving the photopolymerizable layer, and in any case, the dot reproduction range is 2% to 98%. %Met. In the case of Comparative Example 1 containing no diester of the general formula (1), only the silicone rubber layer in the image area can be peeled off without substantially dissolving the photopolymerizable layer, but the development time is long. Also, the dot reproducibility is insufficient. Comparative Example 2 containing distearyl adipate, which is outside the scope of the claims
The developing solution is not suitable as a developing solution because the effect of lowering the interfacial adhesion between the photopolymerizable layer and the silicone rubber layer is small and it is difficult to reproduce fine halftone dots.

[0026]

[Table 1]

Example 5 The protective film was removed from the exposure plate obtained in the same manner as in Example 1 and placed in a mixed solution of 10 parts by weight of dioctyl adipate and 90 parts of polypropylene glycol (weight average molecular weight: 200) for 1 minute. After soaking, Astrazone Red 6B
The development was performed by rubbing with a brush while washing the plate surface with water in which 2% by weight (manufactured by Bayer AG) was dissolved. As a result, a printing plate having good plate inspection properties in which the photopolymerizable adhesive layer in the image area was dyed red was obtained.

The development time is about 3 minutes and the halftone dot reproduction area is 20 minutes.
The 0 line, 2 to 98%, was extremely good.

[0029]

Since the present invention is constructed as described above, the developability is remarkably improved and fine halftone dots can be easily reproduced.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (1)

(57) [Claims] 1. A developer for a waterless lithographic printing plate comprising at least 0.5% by weight of at least one diester having a structure represented by the general formula (1). R ₁ OOC-X-COOR ₂ (1) ( where X is a divalent aliphatic hydrocarbon having 4 to 15 carbon atoms )
In the case of element or an alicyclic hydrocarbon having 5 to 15 carbon atoms, R
₁ , R ₂ is an aliphatic hydrocarbon having 1 to 15 carbon atoms, and X is
In the case of an aromatic hydrocarbon having 6 to 15 carbon atoms, R ₁ and R ₂ are
It is an aliphatic hydrocarbon having 4 to 15 carbon atoms. R _1, R ₂ Waso
Each may be the same or different
No. )