JP2005257846A - Plate correcting liquid for ctp planographic printing plate requiring no dampening water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate correcting liquid which results in a silicon rubber coating having high adhesiveness particularly with a silicone rubber layer of a CTP planographic printing plate requiring no dampening water and having excellent durability. <P>SOLUTION: The correcting liquid contains (a) linear dimethyl polysiloxane having one or more hydroxyl groups at each molecular end, (b) acetoxysilane having two or more acetoxy groups, (c) a catalyst and (d) an adhesion imparting agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plate surface correction solution for a fountain solution-free CTP lithographic printing plate using silicone rubber as an ink repellent layer.

  Various types of fountain solution-free CTP lithographic printing plates with a silicone rubber layer as an ink repellent layer have been proposed. Among them, a photosensitive resin layer and a silicone rubber layer are sequentially coated on a substrate. Has a very excellent performance, and such a structure is commercially available from Toray Co., Ltd. under the trade name “Toray Waterless CTP Flat Plate”.

  When printing using such a printing plate, it is necessary to have a means for erasing and correcting defects such as scratches, pinholes, or defects based on the film edge generated in the silicone rubber layer. It is also necessary to delete the image line portion to make it a non-image line portion.

  For this purpose, it is known to use a method in which a plate surface correction solution comprising a curable silicone rubber solution is applied to a portion to be corrected and cured to form an ink repellent silicone rubber film (for example, (See Patent Document 1). The correction fluid proposed here comprises a linear diorganopolysiloxane having a plurality of functional groups, a crosslinking agent having a plurality of functional groups capable of causing condensation or addition reaction with the functional groups, and, if necessary, a catalyst. The composition is diluted with a solvent containing paraffinic hydrocarbon as a main component. When this correction liquid is used, the purpose of image correction can be achieved. However, there is a problem that the silicone rubber coating formed by applying and drying the correction liquid has insufficient adhesion to the plate surface and is easily peeled off during printing, resulting in poor durability. In particular, it was extremely weak against rubbing during ink cleaning, and the actual situation was that the plate surface cleaning could hardly be repeated.

For improving durability during printing, the addition of a linear diorganopolysiloxane having no functional group or having a functional group only at one end has been proposed (for example, see Patent Document 2). However, there is a problem that the dampening water-free CTP lithographic printing plate has insufficient adhesion to the silicone rubber layer, particularly in a portion with few image areas, and is easily peeled off during printing.
JP 54-22203 A (first page) JP 58-102235 A (first page)

  An object of the present invention is to provide a plate surface correction solution that solves the above-mentioned problems and provides a silicone rubber coating film that is particularly excellent in adhesion to the silicone rubber layer of a dampening-free CTP lithographic printing plate and that is excellent in durability. is there.

As a result of intensive studies, the present inventors have found that this problem can be solved by the following configuration, and have reached the present invention. That is, the present invention contains (a) a linear dimethylpolysiloxane having at least one hydroxyl group at both ends (b) an acetoxysilane having two or more acetoxy groups (c) a catalyst (d) an adhesion-imparting agent. A plate surface correction solution for a CTP lithographic printing plate that does not require dampening water.

  According to the present invention, it is possible to obtain a plate surface correction solution for a CTP lithographic printing plate that does not require dampening water and provides a silicone rubber coating film having good adhesion to the silicone rubber layer and excellent durability.

  The contents of the present invention will be described in detail below.

  First, the linear dimethylpolysiloxane having one or more hydroxyl groups at both ends used as the component (a) in the present invention is particularly preferably one having a weight average molecular weight of 10,000 to 1,000,000. If it is the weight average molecular weight of this range, the adhesive improvement effect is acquired, without impairing handleability. Such linear dimethylpolysiloxane may be used alone or in combination of two or more different types.

  The acetoxysilane as component (b) is an acetoxysilane having 2 or more, preferably 3 or more acetoxy groups capable of reacting with a hydroxyl group. Specific examples include dimethyldiacetoxysilane, methyltriacetoxysilane, tetraacetoxysilane, diethyldiacetoxysilane, ethyltriacetoxysilane, diethyldiacetoxysilane, and propyltriacetoxysilane. Among these, methyltriacetoxysilane, ethyltriacetoxysilane, and tetraacetoxysilane are particularly preferable because of their good curability, adhesion, and solution stability. These acetoxysilanes may be used alone or in combination of two or more.

  The catalyst of component (c) is not particularly limited as long as it promotes the condensation or addition reaction between the hydroxyl group contained in component (a) and the functional group contained in component (b). An organic carboxylate of a metal such as tin, zinc, lead, for example, dibutyltin acetate, dibutyltin laurate, tin octenoate, zinc octenoate, lead naphthenate, or chloroplatinic acid is used. Among these, tin compounds such as dibutyltin acetate, dibutyltin laurate and tin octenoate are particularly preferable.

  The remarkable feature of the present invention is the adhesion imparting agent of component (d). The adhesion-imparting agent enhances the adhesion between the silicone rubber layer of the printing plate and the correction liquid, and examples thereof include an aminosilane coupling agent. Specifically, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldiethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane N-2 (aminoethyl) 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and the like. By adding these adhesion-imparting agents, the adhesion of the correction fluid to the silicone rubber layer of the printing plate has been dramatically improved, and during the printing as well as the plate surface cleaning operation, no peeling occurs at all. Gives a very good coating.

  The preferred composition ratio of the correction fluid used in the present invention is as follows. (A) With respect to 100 parts by weight of linear dimethylpolysiloxane each having one or more hydroxyl groups at both ends, the amount of (b) acetoxysilane having two or more acetoxy groups is preferably 5 to 100 parts by weight, 10-50 weight part is further more preferable. When the amount of acetoxysilane added is 5 parts by weight or more, sufficient adhesive force can be obtained, and the solution stability can be improved. When the amount added is 100 parts by weight or less, sufficient ink repulsion can be obtained. (C) 0.1-50 weight part is preferable and the addition amount of a catalyst has more preferable 0.2-20 weight part. Setting the amount of catalyst added to 0.1 parts by weight or more improves the curing rate, and setting it to 50 parts by weight or less provides sufficient ink repellency and suppresses deterioration of the coating film during long-term storage. can do. (D) The addition amount of the adhesion imparting agent is preferably 0.1 to 30 parts by weight. Adhesiveness improvement effect is acquired by making the addition amount of an adhesion | attachment imparting agent 0.1 weight part, and solution stability becomes favorable by setting it as 30 weight part or less.

  In the correction liquid of the present invention, various fillers can be mixed in order to improve the strength of the silicone rubber coating film obtained by curing the correction liquid. In order to make the coating film easier to see, colorants such as dyes and pigments and other various additives may be mixed.

  Solvents used in preparing the correction fluid include paraffinic hydrocarbons, isoparaffinic hydrocarbons, cycloparaffinic hydrocarbons, aromatic hydrocarbons, carboxylic acid alkyl esters, ethers, ketones, halogenated hydrocarbons, etc. Further, a mixture of these is preferably used, but it is particularly preferable that the main component is a paraffinic or isoparaffinic hydrocarbon from the viewpoint of coating property. Typical examples of such hydrocarbons include petroleum fractions and reformed products thereof.

  The concentration of the solution is generally 5 to 50% by weight, preferably 10 to 30% by weight, although it depends on the molecular weight of the linear dimethylpolysiloxane used, the type of solvent, and the coating method. If the concentration is too low or too high, it is difficult to apply, and a silicone rubber coating film having an appropriate thickness cannot be obtained.

  As an example of the preparation method of the correction liquid, linear polydimethylsiloxane is dissolved in a solvent at room temperature, and then acetoxysilane, a catalyst, an adhesion-imparting agent, and a dye, pigment, filler are added according to the purpose and mixed well. To do.

  The correction liquid of the present invention having such a configuration can be applied to the correction portion using various application tools such as a brush, a cotton swab, a sponge, a pipette, a spoid, and a syringe. Curing and adhesion can also be promoted by heating with an appropriate means after application or irradiation with light.

  The correction liquid of the present invention can be applied to any composition and configuration as long as it is a lithographic material having a silicone rubber layer as an ink repelling part. As useful.

“Toray waterless CTP lithographic plate” manufactured by Toray Industries, Inc. was exposed at an exposure machine “TDL-4400” (manufactured by Toray Industries, Inc.) with an output of 175 mJ / cm ² . Next, CP-1 was used as a pretreatment liquid with a developing machine “TWL-1160F” (manufactured by Toray Industries, Inc.) and developed at a pretreatment temperature of 43 ° C. at 80 cm / min to prepare a printing plate.

  On the image of the printing plate, correction liquids having various compositions shown below were applied using a brush or a spoid and dried at room temperature. The coating film dried within 1 to 2 minutes after coating, and became a strong coating film without stickiness. By this operation, the image is erased and becomes a non-image. The following test was performed after leaving for 5 minutes after application | coating.

A) Printing durability Using a “Sprint” 4-color machine manufactured by Komori Printing Co., Ltd., using water-free ink, performing offset printing, and determining the printing durability of the corrected portion.

B) Washing-resistant isoparaffinic hydrocarbon solvent (Esso Co., Ltd.) “Isopa E” is wiped with a cloth soaked with a waste cloth, and the printing operation is repeated until the corrected wet film disappears and the image appears on the printed matter. Check the number of washings. (Two plate wiping cycles are defined as one cleaning.)
Example 1
<Plate corrector composition 1>
(1) “DMS-S27” (polydimethylsiloxane weight average molecular weight 18,000, manufactured by GELEST): 100 parts by weight (2) methyltriacetoxysilane: 20 parts by weight (3) tetraacetoxysilane: 1 part by weight ( 4) Butyltin acetate: 2 parts by weight (5) 3-aminopropyltrimethoxysilane: 0.5 part by weight (6) “Isopa” E (isoparaffin hydrocarbon mixture, manufactured by Esso Corporation): 400 parts by weight ( 7) Ethyl acetate: 100 parts by weight (8) OIL RED RR (diazo dye, manufactured by Orient Chemical Co., Ltd.): 0.6 parts by weight There is no problem even if the printing durability exceeds 100,000 sheets, and washing resistance There was no problem even if it exceeded 10 times, and a good coating film was obtained.

Comparative Example 1
<Plate corrector composition 2>
It prepared similarly except having remove | excluded the component (5) of Example 1.

  Regarding the printing durability, the coating film was peeled off at 10,000 sheets, and the non-image area became an image area. As for the washing resistance, the coating film was peeled off when it was performed twice, and the non-image area became an image area.

Example 2
<Plate surface correction liquid composition 3>
(1) "DMS-S45" (polydimethylsiloxane weight average molecular weight 110,000, manufactured by GELEST): 100 parts by weight (2) methyltriacetoxysilane: 20 parts by weight (3) tetraacetoxysilane: 2 parts by weight (4) Butyltin acetate: 2 parts by weight (5) 3-aminopropyltrimethoxysilane: 0.5 part by weight (6) “Isopa” E (isoparaffin hydrocarbon mixture, manufactured by Esso Corporation): 350 parts by weight (7) Ethyl acetate: 100 parts by weight (8) OIL RED 5B (diazo dye, manufactured by Orient Chemical Co., Ltd.): 0.4 parts by weight There is no problem with the printing durability exceeding 100,000 sheets, and the washing resistance Even if it exceeded 10 times, there was no problem and a good coating film was obtained.

Example 3
<Plate surface correction liquid composition 4>
(1) “DMS-S51” (polydimethylsiloxane weight average molecular weight 140,000, manufactured by GELEST): 100 parts by weight (2) methyltriacetoxysilane: 20 parts by weight (3) tetraacetoxysilane: 5 parts by weight (4) Butyltin acetate: 2 parts by weight (5) 3-aminopropyltriethoxysilane: 0.5 parts by weight (6) “Isopa” E (isoparaffin hydrocarbon mixture, manufactured by Esso Corporation): 300 parts by weight (7) Ethyl acetate: 100 parts by weight (8) OIL BULLE 613 (triphenylmethane dye, manufactured by Orient Chemical Co., Ltd.): 0.4 parts by weight There is no problem with printing durability exceeding 100,000 sheets, and resistance to washing There was no problem even if the property exceeded 10 times, and a good coating film was obtained.

Example 4
<Plate corrector composition 5>
(1) “DMS-S42” (polydimethylsiloxane weight average molecular weight 80,000, manufactured by GELEST): 100 parts by weight (2) methyltriacetoxysilane: 20 parts by weight (3) tetraacetoxysilane: 2 parts by weight (4) Butyltin acetate: 2 parts by weight (5) 3-aminopropyltrimethoxysilane: 0.1 part by weight (6) “Isopa” E (isoparaffin hydrocarbon mixture, manufactured by Esso Corporation): 300 parts by weight (7) Ethyl acetate: 150 parts by weight (8) OIL RED 5B (diazo dye, manufactured by Orient Chemical Co., Ltd.): 0.5 parts by weight There is no problem with the printing durability exceeding 100,000 sheets, and the washing resistance Even if it exceeded 10 times, there was no problem and a good coating film was obtained.

Claims (1)

(A) a linear dimethylpolysiloxane having at least one hydroxyl group at each end; (b) an acetoxysilane having two or more acetoxy groups; (c) a catalyst; and (d) an adhesion-imparting agent. No plate water correction solution for CTP lithographic printing plates.