JPS62284793A - Direct-image type planographic plate material - Google Patents

Abstract

PURPOSE:To provide a direct-image type planographic plate material having a favorable plate wear property and free of scumming, by providing an image- receiving layer by cross-linking a material obtained by dispersing an inorganic pigment in a specified resin. CONSTITUTION:An image-receiving layer provided on a water-resistant base is formed by crosslinking a material obtained by dispersing an inorganic pigment in a resin comprising a polyhydroxyacrylate polymer and a polyamine- polyamide-epichlorohydrin adduct. The polyhydroxyacrylate polymer comprises 2-hydroxyacrylic acid or a salt derived therefrom, of formula (I), wherein R is -H, -CH3, -C2H5, -C3H7 or -C4H9, M is hydrogen or a Group I metal, and n is an integer of 10-1,500. The polyamide-polyamine-epichlorihydrin adduct is a known one.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field] The present invention relates to a cross-drawing type lithographic printing original plate, and more specifically, by forming a specific blood image-receiving layer on a support, The present invention relates to a lithographic printing original plate in which a non-image area of an image-receiving layer exhibits good hydrophilicity.

[Prior art]

Most of the office printing is done by offset printing presses, and offset printing plates are made by direct printing, which has an image-receiving layer on the support, because it is easy to make plates and it is possible to obtain a printing plate that is faithful to the original. Planographic printing masters are widely used.1 To perform plate making, that is, image formation, on such direct-drawing planographic printing master plates (hereinafter sometimes simply referred to as "printing master plates"), a +11 oil base is generally applied on the image-receiving layer. Draw by hand using ink or print on a typewriter. +t
Measures such as transferring and fixing an oil-based toner image using a plain paper copying machine (RPC) or printing and heat fixing using a thermal transfer printer for a 110-word processor have been adopted.

However, in any case, the printing original plate after image formation is treated with a desensitizing liquid (etching liquid) to desensitize the non-image areas, and a printing plate to be used for offset printing is prepared.

Conventionally, as a representative example of the above-mentioned printing original plate, one in which an image-receiving layer is formed by dispersing an inorganic pigment in a melamine resin or a urea resin is known.

However, in printing plates using such resins,
If the crosslinking reaction of the image-receiving layer is not progressing, the water resistance of this layer will be poor and the printing durability will be low.Also, the heat treatment conditions for forming the image-receiving layer may be set at high temperature for a long period of time, or at room temperature for a long period of time. If the crosslinking reaction of the image-receiving layer is accelerated by storage, etc., the water resistance and printing durability will improve, but the hydrophilicity will decrease.
For this reason, ink adheres to the non-image area of the image-receiving layer during offset printing, causing background stains on printed matter.

As described above, with the conventional techniques, it is difficult to stably obtain a direct-drawing lithographic printing original plate that has both good printing durability and scumming resistance.

〔the purpose〕

The present invention provides a direct-drawing type lithographic printing original plate that has printing durability and does not cause scumming.

〔composition〕

The present invention provides a cross-grain planographic printing original plate in which an image-receiving layer is provided on a water-resistant support, and the image-receiving layer contains an inorganic pigment, a polyhydroxyacrylate polymer, and a polyamide/polyamide-epichlorohydrin adduct. It is characterized by being formed by dispersing it in a resin and subjecting it to a crosslinking reaction.

Incidentally, the present inventor conducted various studies in order to achieve the above objective, and found that the image-receiving layer using the above-mentioned specific resin has already undergone a considerable crosslinking reaction immediately after its formation; It was also confirmed that the crosslinking reaction was almost completed by leaving it to stand, and at the same time, desired printing durability and scumming prevention properties were obtained. The present invention was completed based on these findings.

Examples of the water-resistant support in the present invention include plastic films, synthetic papers, wet-strengthened papers, and the like.

Examples include wet reinforced paper with a waterproof coating layer on one or both sides.

Examples of inorganic pigments include titanium oxide, zinc oxide, kaolin, clay, calcium carbonate, aluminum oxide, and silicon oxide.

These inorganic pigments are dispersed in a binder, and this binder is a resin composed of the aforementioned polyhydroxyacrylate polymer and a polyamine/polyamide/epichlorohydrin adduct.

Polyhydroxyacrylate polymer has Belgian patent No. 8
It is described in the specification of No. 17678 and has the following general formula -fWlfk
ftf7wff=f (However, R is -H, -CI(,, -C,H,, -C,H
, or -C, H, and M are hydrogen or a metal belonging to Group 1 of the periodic table, n is 10 to 1,500, preferably 50 to 1, and is acrylic acid or a salt derived therefrom. Here, if n is smaller than 1O, the water resistance of the image-receiving layer will decrease, resulting in poor printing durability. Conversely, n is 1
If it is greater than 500, the viscosity of the image-receiving layer-forming paint becomes too high, making the coating operation difficult.

On the other hand, polyamide/polyamide/e-epichlorohydrin adducts are also known, and are disclosed in US Patent No. 29261.
It is described in Specification No. 54 and has already been made into components. This is an aliphatic dicarzenic acid having 3 to 10 carbon atoms, such as adipic acid.

It is produced by reacting a basic low molecular weight polyamide derived from succinic acid or the like with a polyalkylene/polyamine, such as diethylenetriamine or tetraedelepentamine, and epichlorohydrin.

-de-hydroxyacrylate polymer and polyamide
Although the ratio of the polyamine/epichlorohydrin adduct to be used is not strictly regulated, it is preferably 0.1 to 0.5 parts by weight of the latter to 1 part by weight of the former. The latter (1 part by weight of the former (polyhydroxyacrylate 1 combination))
Polyamide-polyamine-epichlorohydrin/) is 0.
If it is less than 1 part by weight, printing durability will be reduced, and if it is more than 0.5 part by weight, the viscosity of the image-receiving layer forming coating material will increase, making coating difficult.

As mentioned above, the resin as a condensation agent is composed of such a polyhydroxyacrylate polymer, a polyamide polyamine, and epichlorohydrin, and the amount of this resin used is 0.2 to 0.0 parts per 11 parts of the inorganic pigment. 5 parts by weight is preferred. If it is less than 2 parts by weight of α, there is a tendency for printing durability to decrease, and conversely, if it is more than 1 part of o, s3131, image receptivity decreases, that is, toner retention of RPC or transferred ink layer retention of thermal transfer printers. A decrease is seen.

The adhesion amount of one image-receiving layer is suitably 5 to 15 I/ze. When a resin other than the above-mentioned resin is used together as a binder, the amount of the resin needs to be 500 parts by weight less than the total binder.

In the present invention, if necessary, an intermediate layer can be provided between the water-resistant support and the image-receiving layer in order to improve interlayer adhesion and further provide water resistance. A back coat layer can be provided on the support surface to provide an anti-curl effect.

In order to produce the printing original plate of the present invention, an aqueous solution or aqueous dispersion containing the above-mentioned specific resin and inorganic pigment is coated on one side of a water-resistant support and dried to form a 1Ili image-receiving layer. good.

Next, examples and comparative examples will be shown. Note that both parts and parts here are based on the amount of X.

Example 1 Paints with the following composition were applied to both sides of wet reinforced paper with a basis weight of 601/m, and dried with hot air at 130°C for 15 seconds to give a coating weight of about 13 I/l each. A support was created.

Calzexy-modified SBR latex (50% non-volatile content)
1 part casein in aqueous ammonia (10% non-volatile content)
) 50% aqueous dispersion of 0.2 parts clay
2 parts water
1.5 parts On the other hand, 1 part of polyhydroxyacrylic acid sodium salt (molecular weight approximately 35,000) and 58 parts of water
was added and dissolved. 0.2 part of polyamine/polyamide/epichlorohydrin adduct was added to this aqueous solution and mixed to prepare a resin solution. 50% aqueous dispersion of clay 3.2 parts 50% aqueous dispersion of silicon oxide
2 parts 50% aqueous dispersion of zinc oxide 2 parts water
6 parts were added and mixed and dispersed to prepare a paint for forming an image-receiving layer. Subsequently, this pigment was coated on the water-resistant support and dried with hot air at 130° C. for 20 seconds to form an image-receiving layer having a coating weight of about 1217 trj.

This was then subjected to llft by Super Calendar to create an original plate for drawing-type planographic printing.

Example 2 Hydroxyacrylic acid potassium salt (molecular weight approximately 6800)
Add 4.5 parts of water to 1 part and dissolve polyamide/11.
A printing original plate was prepared in exactly the same manner as in Example 1, except that 0.3 part of polyamide/epichlorohydrin adduct was added and mixed to prepare a resin solution.

Example 3 Polyhydroxyacrylic acid sodium salt with a molecular weight of about 35
Molecular weight from about 000 to about zsooo.

A printing original plate was prepared in exactly the same manner as in Example 1 except that the printing plate was replaced with a different one.

Example 4 Example 1 except that the amount of the polyamine/polyamide/epichlorohydrin adduct was changed from 0.2 parts to 4.5 parts.
It stopped (I made the original printing plate in the same way.

Comparison Example To 10 parts of a 10% water bath of polyvinyl alcohol (degree of polymerization: 1800), add 0.25 parts of an 80% water bath of melamine resin and 0.25 parts of a 10% water bath of ammonium chloride and mix to make a resin. A comparative printing original plate was prepared in exactly the same manner as in Example 1 except that the solution was prepared.

The original printing plate prepared as described above was printed using a word processor wire tod printer and thermally fixed to obtain a printing plate. When printing was performed with this plate, Example I
With T 2 m 3 and 4, many clear prints were obtained. On the other hand, in the case of the comparative example, background smear appeared earlier when printing a large number of sheets.

In addition, in the image-receiving layer of the printing original plates in Examples 1, 2.3, and 4, the crosslinking reaction has already progressed considerably immediately after formation, but if these printing original plates are left at room temperature for about a week, the crosslinking reaction will occur. It is confirmed that it is almost completed. On the other hand, in the image-receiving layer of the printing original plate in Comparative Example, the crosslinking reaction did not progress much immediately after formation, and it was confirmed that crosslinking was still insufficient even after being left at room temperature for one month.

〔effect〕

The drawing-type lithographic printing original plate of the present invention as described above uses a specific resin as a binder in the image-receiving layer, so that a structural reaction is carried out well, and a printing plate suitable for printing a large number of sheets is provided. It is effective for

Claims (1)

[Claims] 1. An image-receiving layer is provided on a water-resistant support by dispersing an inorganic pigment in a resin containing a polyhydroxyacrylate polymer and a polyamine-polyamide-epichlorohydrin adduct, and subjecting it to a crosslinking reaction. Original plate for direct drawing type lithographic printing.