JPH0876366A - Plate surface modifying solution for waterless planographic printing plate - Google Patents

Abstract

PURPOSE: To form a coating film emitting no irritant odor, excellent preservation stability and excellent also in printing resistance. CONSTITUTION: This plate surface modifying soln. for modifying the image area of a waterless planographic printing plate with a silicon rubber layer as an ink-repellent layer to a non-image area contains (a) 10 pts. wt. linear orgapopolysiloxane having three alkoxy groups at each of both terminals, (b) 0.01-5 pts.wt. Ti-contg. condensation catalyst,(c) 10-500 pts.wt. org. solvent and (d) an alkoxysilane compd. represented by the formula Rm Si(OR<1> )n [where R is alkyl, vinyl or phenyl, R<1> is methyl, ethyl or propyl, (m) is an integer of 0-2, (n) is an integer of 2-4 and m+n=4]. The alkoxysilane compd. is contained by such an amt. as to regulate the concn. of functional alkoxy groups in this modifying soln. to 0.1-1.5mol/l.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate surface correction liquid for a waterless planographic printing plate having a silicone rubber layer as an ink repellent layer.

[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. Among them, Japanese Patent Publication No. 54-26923 and Japanese Patent Publication No. 5
It is general that a photosensitive resin layer and a silicone rubber layer are applied in this order on a base plate disclosed in JP-A-6-23150, JP-B-55-22781, and JP-A-2-226249. These lithographic printing plates have many advantages because they do not require fountain solution during printing. However, since the silicone rubber layer is relatively easily scratched, scratches are likely to occur during handling. For this reason, there have been proposed some plate surface correction liquids for waterless lithographic printing plates capable of correcting scratches, pinhole-like defects, defects due to film edges, etc. generated in the silicone rubber layer.

Japanese Patent Publication No. 61-3417 discloses a plate surface correction solution comprising a one-pack type curable silicone rubber solution containing triacetoxysilane as a cross-linking agent. Further, JP-A-62-299854 discloses a plate surface correction liquid comprising a one-pack type curable silicone rubber solution containing a vinyloxysilane compound as a crosslinking agent. Further, JP-A-4-163195 discloses a plate surface correction liquid using a linear organopolysiloxane having three alkoxy groups at both ends. This plate surface correction liquid has no irritating odor, its cured film has excellent adhesion to the image area, does not cause printing stains, gives a film with excellent printing durability, and is at a level that is practically satisfactory for printing. However, the storage stability of the liquid in the plastic container from the time of production to the use by the user is not sufficient, and gelation may occur in the container within a year depending on the conditions.

[0004]

Therefore, the object of the present invention is to have no irritating odor, to have excellent printing durability, to prevent gelation in the container during distribution and storage, and for a long time after production. ,
For example, it is to provide a plate surface correction liquid having improved storage stability that can be used for one year or more.

[0005]

The present invention provides a plate surface correction liquid for correcting an image area to a non-image area in a waterless lithographic printing plate having a silicone rubber layer as an ink repellent layer, which comprises (a) Linear organopolysiloxane having 3 alkoxy groups at each end (10 parts by weight), (b) titanium-based condensation catalyst (0.01 to 5 parts by weight), (c) organic solvent (10 to 5)
00 parts by weight), and (d) an alkoxysilane compound represented by the following general formula (1), wherein the alkoxysilane compound has a functional group concentration of the alkoxy group of the alkoxysilane compound in the plate surface correction liquid of 0. It is a plate surface correction liquid for a waterless planographic printing plate, which is contained in an amount of 1 to 1.5 mol / L. R _m Si (OR ¹ ) _n (1) (wherein R is an alkyl group, a vinyl group, a phenyl group, a substituted alkyl group, a substituted vinyl group or a substituted phenyl group,
R ¹ is a methyl group, an ethyl group or a propyl group, m
+ N = 4, m is 0, 1 or 2, and n is an integer of 2 or more. )

In the present invention, the linear organopolysiloxane having 3 alkoxy groups at each end used as the component (a) is preferably represented by the following general formula (2) or (3). Is. (R ³ O) ₃ Si-C ₂ H ₄ -Si- (O-Si (R ² ) ₂ ) _-p C ₂ H ₄ -Si (OR ³ ) ₃ (2) (R ³ O) ₃ Si- ( OSi (R ² ) ₂ ) _-p OSi (OR ³ ) ₃ (3) where R ² is a monovalent hydrocarbon group having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, Examples thereof include an alkyl group such as a hexyl group, an aryl group such as a phenyl group, and an aralkyl group such as a β-phenylethyl group and a β-phenylpropyl group. Of these, a methyl group is preferred because it is easy to synthesize, and when it is used as a plate surface correction liquid, it is excellent in the resilience of printing ink. R ³ is a methyl group, an ethyl group or a propyl group, and a methyl group is preferable from the viewpoint of curability. p is a number of 50 to 1000. If it is less than 50, the coating film becomes hard and the printing durability and ink resilience are poor, and if it is more than 1000, the curability is poor.

Examples of the titanium-based condensation catalyst as the component (b) include tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate and tetraisopropenyloxy titanate. Compared to other tin, zinc, and lead-based catalysts, the titanium-based catalysts are superior in curability at room temperature and excellent in liquid stability in the combined use system with the component (a). The component (b) is used in an amount of 0.01 to 5 parts by weight based on 10 parts by weight of the component (a).

The type of the organic solvent as the component (c) is not particularly limited as long as it can dissolve the components (a) and (b), but it is rapidly evaporated at room temperature and wettable to the plate surface. Good things are desirable. Specific examples of such an organic solvent include aliphatic hydrocarbons such as n-hexane and n-heptane, aromatic hydrocarbons such as toluene and xylene, ethyl acetate, n-propyl acetate, isopropyl acetate and n-butyl acetate. , Isobutyl acetate, methyl propionate, isopropyl formate, n-propyl formate, isobutyl formate, n formate
-Esters such as butyl, and mineral spirits. In order to obtain a smooth coating film, it is possible to use a plurality of solvents in combination, for example, a mixture of an aliphatic hydrocarbon and an ester. In order to obtain a good coating film thickness, the amount of the organic solvent is preferably 10 to 500 parts by weight, more preferably 20 to 100 parts by weight, based on 10 parts by weight of the component (a).

Specific examples of the alkoxysilane as the component (d) include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane and vinyltrimethoxysilane. Methoxysilane and the like can be mentioned. Moreover, these partial hydrolyzates also give the same effect. In equation (1),
n is selected from an integer of 2 or more and 4 or less, preferably 3 or more, and more preferably 3. In order to give good storability, the alkoxysilane as the component (d) is contained in such an amount that the functional group concentration of the alkoxy group becomes 0.1 to 1.5 mol / L, more preferably 0.3 to It is 1.5 mol / L.

It is also preferable to add other additives (for example, surfactants, dyes, pigments, inorganic powders, silane coupling agents, etc. for improving coating properties) to the correction liquid of the present invention. The waterless lithographic printing plate used in this case is one in which a photosensitive layer and a silicone rubber layer are sequentially laminated on a substrate. Examples of such waterless lithographic printing plates include JP-B-44-23042 and JP-B-46- No. 16044,
Japanese Patent Publication No. 51-17081, Japanese Patent Publication No. 54-26923
No. 55, Japanese Patent Publication No. 55-22781, Japanese Patent Publication No. 56-2315
No. 0, JP-A-2-236550, JP-A-56-800.
64, JP-A-3-1555553, JP-A-3-161.
The waterless planographic printing plate disclosed in Japanese Patent No. 753 and the like can be mentioned. To correct the plate surface of a waterless planographic printing plate using the present invention, a waterless planographic printing plate obtained by sequentially laminating a photosensitive layer and a silicone rubber layer on a substrate is subjected to image exposure, and after development, a film is formed. The above-mentioned plate surface correction liquid may be applied to the image defect portion due to an edge or dust and dried and cured.
A variety of storage containers and coating methods for the plate surface correction liquid are possible.
For example, a method of putting in a container like an ink fountain and applying with a paintbrush, a method of filling and using a felt-tip pen as ink, a method of applying by spraying in a spray can, and the like are possible. However, the plate surface correction method of the present invention is not limited to these coating methods.

[0011]

The correction liquid of the present invention gives a coating film having no storage odor and excellent storage stability and printing durability.

[0012]

The present invention will be described in detail with reference to the following examples.
Positive type waterless photosensitive lithographic printing plate TAP (manufactured by Toray Industries, Inc.)
After image exposure, the silicone rubber in the image area was peeled off by rubbing with gauze while being immersed in n-heptane to obtain a printing plate. This printing version is Heidelberg GT
OYOKING ULTRA manufactured by Toyo Ink Co., Ltd.
When 1000 sheets of TUK AQUALESS G black ink were printed, the ink was temporarily stopped, and the correction solutions (Examples 1 to 3 and Comparative Examples 1 to 3) shown in Table 1 were applied to a part of the image area with a cotton swab, and then 2 minutes. After that, the printing was restarted, and 100,000 sheets were further printed to finish the printing. In addition, these correction fluids were treated with high-density polyethylene (density 0.
958) Put 1.5g in a plastic container (wall thickness 0.5mm, capacity 2ml) and seal it at 45 ℃ / 75RH%.
It was stored in the constant temperature and humidity chamber for 50 hours. The results are shown in Table 1.

[0013]

[Table 1] ─────────────────────────────────── Component Example Comparative Example 1 2 3 1 2 3 Organopolysiloxane 10 10 10 10 10 10 (Formula 4) Dimethyldimethoxysilane 1 Methyltrimethoxysilane 1 0.1 Tetramethoxysilane 15 Tetrabutyl titanate 1 1 0.1 1 1 1 0.1 n-Hexane 10 10 10 10 10 10 Isopropyl acetate 30 30 30 30 30 30 Oil Pink 312 0.1 0.1 0.1 0.1 0.1 0.1 (manufactured by Orient Chemical Co., Ltd.) Functionality of alkoxy group 0.33 0.44 0.53 0.02 0.06 2.2 Group concentration mol / L Erase after restarting printing 100,000 100,000 10 Printing capacity of 100,000 to 10 10 or more (printing number) or more or more or more or more 20 45 ° C / 75RH% Liquid liquid Liquid liquid Gelation Gelation Liquid Liquid state after 50 hours (CH ₃ O) ₃ -Si- (OSi ( CH ₃ ) ₂ ) _-300 OSi- (OCH ₃ ) ₃ (4)

Claims (1)

[Claims] 1. A plate surface correction liquid for correcting an image area to a non-image area in a waterless planographic printing plate having a silicone rubber layer as an ink repellent layer, comprising: (a) three alkoxy groups at each end. Containing a linear organopolysiloxane (10 parts by weight), (b) titanium-based condensation catalyst (0.01 to 5 parts by weight), (c) organic solvent (10 to 500)
Part by weight), and (d) an alkoxysilane compound represented by the following general formula (1), wherein the alkoxysilane compound has a functional group concentration of the alkoxy group of the alkoxysilane compound in the plate surface correction liquid of 0.1. A plate surface correction liquid for a waterless planographic printing plate, which is contained in an amount of up to 1.5 mol / L. R _m Si (OR ¹ ) _n (1) (wherein R is an alkyl group, a vinyl group, a phenyl group, a substituted alkyl group, a substituted vinyl group or a substituted phenyl group,
R ¹ is a methyl group, an ethyl group or a propyl group, m
+ N = 4, m is 0, 1 or 2, and n is an integer of 2 or more. )