JPS627596A - Damping water for printing - Google Patents

Abstract

PURPOSE:To enable damping water to be stably used for printing, by adding specified quantities of a hexacyanoferrate (II) and a phytic acid salt to damping water. CONSTITUTION:The damping water comprises at least a hexacyanoferrate (II) in an amount of 0.1-20g/l and a phytic acid salt in an amount of 0.01-10g/l. A pH adjustor, a buffering agent, a wetting agent, a rust preventive or the like may be added to the damping water. The hexacyanoferrate (II) is represented by the general formula M4[Fe(CN)6], wherein M is Li, Na, K, NH4, Rb, Cs or the like. The phytic acid salt may be an alkali metal salt, ammonium salt, an amine salt or the like of phytic acid. As the pH adjustor or buffering agent, at least one inorganic or organic acid or salt thereof is used either singly or in combination. A main reaction for providing hydro philicity is performed by the hesacyanoferrate (II), while the small amount of the phytic acid salt causes a reaction for moderate suppression of ink built-up, thereby making the entire surface of a master less susceptible to con tamination.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention relates to electrophotographic offset masters, silver salt printing plates, P
Concerning dampening water used for printing 8th edition.

[Prior Art] In an electrophotographic offset master, a lipophilic image is first obtained by an electrophotographic method on a photosensitive layer formed by coating a photoconductive fine powder such as zinc oxide on a support together with an electrically insulating resin. Next, the non-image area is converted from lipophilic to hydrophilic by etching treatment to form a printing plate. In order to maintain the initial hydrophilicity in the printing plate, an etching solution is usually diluted several times and used as a dampening solution.

There is also a method of writing directly on a master using a lipophilic writing instrument or a type to create a printing plate, and a method of using an electrophotographic transfer method. In this case, use the same dampening water.

Many dampening solution formulations have been proposed so far.

If they are classified according to their main components, they can be divided into yellow blood salt type and non-yellow blood salt type. Yellow blood salt systems have traditionally been used. Although it is unstable to heat and light and has drawbacks such as a decrease in etching power, generation of precipitation, and pollution properties even with natural aging, it can be said that the overall printing characteristics are stable.

[Problems to be Solved by the Invention] However, there are cases in which printing cannot be achieved with yellow blood salt systems. That is, when printing with quick-drying colored inks conventionally used in PS plates, staining, roller stripping, emulsification, etc. are likely to occur in the printed matter, making it impractical. Furthermore, acid-free paper has recently been increasingly used for printing paper. Acid-free paper is very similar in appearance and feel to conventional acid-based paper and is therefore easily distinguishable. For this reason, there are some confusing cases where printing is done without knowing ζ and stains are inevitably removed.

It is well known that increasing the number of times of etching or lowering the pH of the dampening water does not provide a fundamental solution.

On the other hand, a typical example of a non-yellow blood salt type is a phytate type. However, phytate alone has a weak hydrophilicity and is problematic for use as an etching solution. However, if this is diluted and used as dampening water, printing may be possible to some extent despite some problems. The problems are that the printing condition is unstable, and if the water and ink caps are not always connected, dirt and water corrosion are likely to occur, printing durability is likely to be poor, and roller strips are likely to occur. It is.

However, as a result of detailed and rigorous research and logical considerations, the present inventors have discovered that in each case, the cause of the above-mentioned troubles is calcium carbonate contained in the ink and neutral paper. In other words, calcium carbonate is dissolved into dampening water during printing, and a hydrophilic reaction product of calcium ions and dampening water components is produced. When this is deposited on the roller surface of the printing press, it becomes a roller strip, and the master toner is removed. If it adheres to the image area, printing durability will be poor. Furthermore, the eluted calcium carbonate increases the pH of the dampening water, inhibits the hydrophilization reaction, and causes stains.

[Means for Solving the Problems] Therefore, the present inventors proposed a method in which calcium carbonate is not eluted, a method in which calcium carbonate is not reacted with the dampening water component even if it is eluted, or a method in which a hydrophilic reactant is not generated even if it is reacted. And P.H.
As a result of searching for a method that would not increase the water content, it was discovered that when yellow blood salt and phytate were used together in a specific amount, a dampening solution that could be stably used in any case could be obtained. It was. Although the effects of each have not yet been completely elucidated, yellow blood salt is responsible for the main hydrophilic reaction, and a small amount of phytate causes a mild inking reaction, making the entire surface of the master less likely to stain. It is thought that the For this reason, it is thought that the stains that occur when a yellow blood salt system is used alone do not occur at all, and the problems that occur when a phytate system is used alone do not occur.

In the present invention, inorganic or organic M!, as described later, is used as a PH regulator or 'X'H@filtering agent. ! ``You can add as many salts as you want, but they also change the reaction,
It is thought that it is working to promote it efficiently.

The proposal to use yellow blood salt and phytate in combination was published in the Special Publication Act in 1978-2.
4609, as shown in Special Publication No. 54-10003,
These were made to improve the performance as an etching solution, and the essence is that phytate has inferior etching power compared to yellow blood salt, so the two were used together to compensate for the drawbacks. I think that the. Within the range of the addition amount of yellow blood salt of the present invention, printing can be performed without any problem under normal printing conditions such as acidic paper and black ink (of course, background stains occur with color inks and neutral paper). However, if phytic acid is used alone within the range of addition amount, background smear will occur even under normal printing conditions. The reason for this is presumed to be that the hydrophilization reaction cannot occur within this addition amount range. Only when yellow blood salt and phytic acid are used in combination, it becomes possible to print with colored inks or neutral paper using the mechanism described above.

That is, the present invention provides at least 0.1 to 20 g of yellow blood salt.
/ls This is a printing fountain solution containing 0.01 to 10 g/z of phytate.

In the present invention, a PH adjuster, a PH buffer, a wetting agent, a leakage agent, a rust preventive agent, etc. can be further added.

PL[ is preferably used in a range of 3 to 7.

Materials that can be used in the present invention will be explained below.

Yellow blood salt is generally represented by 2M4 [F・(ON)6 pieces (
Here, M is TJi, N&, NH4, and Rb.

Om). Especially in the case of M&, it is extremely preferable in terms of performance and cost.

Phytic acid salts include alkali metal salts, ammonium salts, and amine salts of phytic acid.

Inorganic or organic acids or salts thereof may be used as the PH regulator or PH buffer, and they may be used alone or in combination. For example, inorganic acids include phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid; organic acids include formic acid, acetic acid, butyric acid, valeric acid, lactic acid, tartaric acid, and propionic acid; Glutaric acid, maleic acid, phthalic acid, citraconic acid, itaconic acid, hexamalic acid, tricarballylic acid, glycolic acid, propionic acid, thioglycolic acid, malic acid,
Examples include citric acid, gluconic acid, pyruvic acid, gelcholic acid, salicylic acid, adipic acid, hydroacrylic acid, glyceric acid, P-)luenesulfonic acid, and polyacrylic acid. Examples of the salts include alkali metal salts, ammonium salts, and amine salts.

Acids or salts having an acid dissociation constant of 10-2 to 10 are preferred.

In addition, ethylene glyfur, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, gum arabic, carboxymethyl cellulose, acrylic polymer, methanol, ethanol, isopropyl alcohol, normal propyl alcohol, triethanolamine, etc. may be added as wetting agents and softening agents. can. In order to prevent precipitation of Prussian blue and tumble blue due to decomposition of yellow blood salts, it is desirable to add a chelating agent such as EDTA-2N&.

In the present invention, in order to fully exhibit the desensitizing effect of the yellow blood salt, it is preferable to add a phosphate, and the phosphate is an alkali metal salt of orthophosphoric acid, monophosphoric acid, or diphosphoric acid. and ammonium salts.

Furthermore, salicylic acid, phenol, butyl phenol-parabenzoate, sodium dehydroacetate, 4-inchazolon-6-one compound, etc. can be added as preservatives.

Aspects of the present invention are shown below.

A printing fountain solution containing at least 0.1 to 20 g/j of yellow blood salt/0.01 to 10 g/j of As'itate and having a PIN of 6 to 7.

Embodiment 2〉Mountain water for printing, more preferably containing 1 to 10 g of yellow blood salt/0.1 to 5 g/j of As phytate and having a pH of 3 to 7.

Embodiment 3　Embodiment 1　 further contains a PH adjuster, a PH buffer, a wetting agent, a wetting agent, a preservative, a rust preventive, etc. Examples of the present invention are shown below. However, the present invention is not limited by this.

Example 1 Yellow Blood Ammonium 4.0g Monosodium Phosphate 15.0g Phytic Cup
2.0g water 1
000.0g Using dampening water according to this formulation, a master plate was made and etched using the Fu±Film KLP system and printed on neutral paper. I was able to print 10,000 sheets clearly without any smudging from the start of printing. When printing continued while replenishing this dampening water, a total of 50,000 sheets were printed in 5 editions. There were no problems such as smudges, roller strips, or water damage during printing.

Comparative Example 1 Anemia Sodium 4.0g Phosphorus #1
1 Sodium 15.0g water
1000.0g Then, when I changed to a new master and printed again, scumming occurred from the beginning of printing.

Comparative example 2 Sodium phytate 12.0g water
1000.0 g When printing was carried out under exactly the same conditions as in Example 1, 70
Printing durability failure occurred on 00 sheets. There, I changed to a new master at 1' and printed again, and the result was 5000.
The print life was on the poor side.

Example 2 Anemic sodium 5.0g monosodium phosphate 15.0g gluconic acid
15.0 g:.

Sodium phytate 1.0g water
When printing was carried out under exactly the same conditions as in Example 1 except that the 1000.0 g ink was replaced with D-07 gloss ultramarine blue, no background smudges or poor printing durability occurred on more than 60,000 copies.

Example 3 Anemia potassium 4.0g phosphorus iv1
Sodium 10.0g Phytin i!
85g Glyco-AI #16.0
g water 1000.0
g When printing was carried out under exactly the same conditions as in Example 1, no scumming occurred on more than 50,000 sheets.

Example 4 Anemia Potassium 4.0g Monopotassium phosphate 20.0g Potassium phytate 2.0g Apple #
6. OgKD'L'Mu-2N&
0.4g glycerin 8
．． 0g4-thiazolone-3-one compound 0.02
g water 1000.0
g When printing was carried out under exactly the same conditions as in Example 1, no background smear occurred on more than 50,000 sheets. In addition, after using it continuously for a month while continuing to replenish it, there was dirt on the surface.
There was no occurrence of roller stripping, water damage, mold, sludge, sediment, rust, etc., and stable and clear printed matter was always obtained.

[Effects of the Invention] As described above, when using the dampening solution of the present invention, a large number of printed matter can be obtained without causing problems such as scumming.

Claims (1)

[Claims] A printing fountain solution containing at least 0.1 to 20 g/l of yellow blood salt and 0.01 to 10 g/l of phytate.