JPS613797A - Direct drawing type planographic printing base plate - Google Patents

Abstract

PURPOSE:To enable the prevention of printing contamination and long-term preservation, by containing specific acetylene glycol in a surface recording layer. CONSTITUTION:Acetylene glycol represented by formula (wherein R1 is a hydrogen atom or a CH3-group and R2 is a hydrogen atom or a -CH2-CH2OH group) is contained in a surface recording layer and the addition amount thereof is set to 0.1-10wt% of the surface recording layer. As the hydrophilic resin component in a binder, PVA or starch is used and the mixing ratio of the hydrophylic resin and a waterproofing agent is different by the kind of the hydrophylic resin and the waterproofing agent to be used but generally (1-4):(4-1) on a wt. basis. As pigment, clay or titanium oxide is used and the use amount thereof is 1:(0.7- 4) on a wt. basis in a binder/pigment ratio. By this method, printing contamination can be prevented and the wettability of the surface layer to the high temp. preservation in summer is not changed and long-term preservability is secured while reliability is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a direct plate lithographic printing original plate on which an image is directly formed.

Conventional technology Direct-drawn lithographic printing original plates can be used for various printers such as pencils, ballpoint pens, typewriters, word processors, and PPC (
This is a type in which platemaking is performed directly on the surface layer using an electrophotographic copying machine (for copying plain paper), for example, on a water-resistant support such as water-resistant treated paper. A paint whose main components are a binder consisting of a water-resistant agent such as formaldehyde resin, urea-formaldehyde resin, or glyoxal, and a pigment such as clay or zinc oxide is applied and dried and hardened to form a water-resistant surface recording layer. It is manufactured by providing However, if the amount of water-resisting agent added to the lithographic printing original plates obtained in this way is increased for the purpose of improving printing durability, printing stains may occur, and especially when stored at temperatures of 40 to 50°C, such as when stored in a warehouse during the summer.
If stored in a moderately warm environment, water resistance will progress and printing will become smudged. Therefore, if the amount of the water-proofing agent is reduced, image peeling or wrinkles occur, resulting in a decrease in printing durability. In addition, foaming tends to occur in the paint when forming the surface recording layer.
For this reason, coating defects often occur in the surface recording layer.

Purpose The first purpose of the present invention is to improve the wettability of the surface recording layer so that there is no quality deterioration such as printing stains even when stored in high temperature environments, and there is no occurrence of image peeling or wrinkles. ,
To provide an original plate for direct lithography printing having excellent printing durability. A second object of the present invention is to provide a high-quality direct plate lithographic printing original plate having a surface recording layer free from coating defects by preventing foaming of the paint during formation of the surface recording layer.

Structure The original plate for direct drawing type lithographic printing of the present invention is a plate for direct drawing type lithographic printing in which a surface recording layer mainly composed of a binder made of a hydrophilic resin and a waterproofing agent and a pigment is provided on a water-resistant support. , the surface recording layer further contains acetylene glycol represented by the general formula % (where R6 represents a hydrogen atom or a CH, group, and - represents a hydrogen atom or a -CH, -CI, -OH group). It is characterized by:

The acetylene glycol of the general formula used in the present invention has excellent wettability with water, and has the effect of improving the wettability of the plate surface with etchant and dampening water used during printing and preventing printing stains. Furthermore, this acetylene glycol has the effect of preventing foaming during coating of the coating material for the surface recording layer, so that a surface recording layer without coating defects can be formed. The amount of such acetylene glycol added is 0.1% to 10%, preferably 0.5% of the weight of the surface glossy image layer.
% to 5%. Below 0.1%, the wetting effect is small;
If it is more than 10%, water resistance deteriorates and splatter occurs in the surface layer coating process, which tends to cause uneven coating of the surface layer.

Hydrophilic resin components in the binder, which is the main component of one of the surface recording layers, include PTA, powders (for example, starch, acetyl starch, methyl starch, phosphate ester starch, etc.), cellulose MiC Example 1f methyl cellulose, ethyl cellulose. , hydroxyethyl cellulose, carboxymethyl cellulose, etc.). Further, as the waterproof agent, amino resin initial condensates such as melamine formaldehyde and urea formaldehyde, glutaraldehyde, glyoxal, and modified polyamide resins can be used. The mixing ratio of the hydrophilic resin and the water-resistant agent The pigments that are the other main components of the surface recording layer include clay, titanium oxide, zinc oxide, barium sulfate,
Examples include those conventionally used such as silica, aluminum oxide, and calcium carbonate. The amount used varies depending on the pigment, but the binder:pigment ratio is 1:(0.7-4)('IL
(view) level is appropriate.

Examples of the water-resistant support include paper and water-resistant plastic films treated with oil-soluble resins such as styrene-butadiene copolymer and, if necessary, pigments as described above. Note that when paper is used, a back coat layer can be provided on the opposite side of the water-resistant layer.

To make the lithographic printing original plate of the present invention, an aqueous dispersion containing a predetermined amount of a water-resistant agent, a hydrophilic resin pigment, and acetylene glycol is applied to the water-resistant layer surface of a water-resistant support, and then dried and cured by heat treatment. to reduce the adhesion amount to 1 to 3 opitrr.
It is sufficient to provide a surface recording layer of about 100 mL.

The present invention will be explained below by way of examples.

Example 12o1. A 35% aqueous dispersion of styrene-butadiene copolymer/clay (1/1 by weight) was coated on one side of /rl high-quality paper and dried to form a water-resistant layer with a coating weight of 1 OII/d, and vice versa. A 6% aqueous solution of borivinyl alcohol was applied to the surface and dried to provide a hydrophilic resin layer with a coating weight of 21/ze. Next, a 20% aqueous dispersion containing the composition shown in Table 1 was applied to the water-resistant layer surface of the obtained water-resistant support, and dried and cured at 125°C for 3 minutes to form a surface recording layer with a coating weight of 51/d. Established.

Table-1 Qin 2. 4. 7. 9-Tetramethyl-5-decyne-4,7-diol For comparison, a surface recording layer was provided in the same manner as in Example 1 using the same formulation as in Table 1 but without adding acetylene glycol.

The obtained lithographic printing original plate was stored at 50'C for one month, and the contact angle with water and the results of plate making using a commercially available RPC copying machine and offset printing are shown in Table 2.

Table 2 As can be seen from Table 2, the products of the present invention produced clear printed matter without staining even after storage.

Example 2 In the acetylene glycol general formula used in Example 1, R
1: CH@s FL* : CHt −CHt O
A surface recording layer was provided in the same manner as in Example 1 except that a compound of H (ethylene addition mole number: 3.5) was used to prepare an original plate for lithographic printing, and as a result of testing, it showed good performance as in Example 1. showed that.

Effects As described above, the lithographic printing original plate of the present invention has improved wettability of the surface recording layer with respect to etchant and dampening water, and as a result, printing stains can be prevented, and the wettability of the first surface layer is particularly improved during high-temperature storage in summer. In addition to being able to withstand long-term storage without any change in the surface recording layer and improving reliability, it is also possible to prevent foaming of the paint during formation of the surface recording layer, thereby forming a surface layer free from coating defects.

Claims (1)

[Scope of Claims] 1. In a direct drawing type lithographic printing original plate in which a surface recording layer mainly composed of a pigment and a binder made of a hydrophilic resin and a waterproofing agent is provided on a water-resistant support, the surface The recording layer further contains acetylene glycol represented by the general formula ▲ Numerical formulas, chemical formulas, tables, etc. An original plate for direct drawing type lithographic printing characterized by the following.