JPS6221640B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a processing liquid used for desensitizing various lithographic printing original plates. Currently, lithographic printing original plates include electrophotographic original plates of the type that have a photosensitive layer in which inorganic photoconductive particles such as zinc oxide particles are dispersed in a resin binder, and images are formed by electrophotography; It has an image-receiving layer in which inorganic pigments such as titanium oxide are dispersed in a resin binder, and it is possible to write directly on this layer with oil-based ink.
A type of direct plate that forms an image by typing, or a photosensitive layer of photocurable resin is placed on a grained aluminum plate, and the difference in solubility between exposed and non-exposed areas of this photosensitive layer is utilized. A type of PS plate that forms an image using the same method is known. After forming an oleophilic image on each of these lithographic printing original plates, a process is performed to make the non-image area on the plate surface hydrophilic, that is, a desensitizing process.
The original plate processed in this way is used as a master for printing. The treatment liquid used for desensitization treatment generally contains at least one of hydrophilic resins such as gum arabic and polyvinylpyrrolidone, phosphates, aluminum alum compounds, and acids (organic acids or inorganic acids). However, these processing solutions cannot be said to be fully satisfactory processing solutions. Specifically, the former treatment liquid cannot form a hydrophilic film with high physical strength, and the film formation speed is slow, so printing is performed with an original plate (master) treated with this treatment liquid. However, there are disadvantages such as background stains on printed matter even when a small amount of printing is done, and ink difficult to separate. On the other hand, the latter treatment liquid has a stronger desensitizing power than the former treatment liquid, and can form a hydrophilic film with high physical strength.
Although it has the advantage of being fast in film formation, it has the disadvantage that it may become colored or precipitate due to light or heat, making its desensitizing ability unstable. Furthermore, a processing liquid that can eliminate the drawbacks of the above-mentioned processing liquid for lithographic printing is disclosed in Japanese Patent Publication No. 45-24609, but this processing liquid partially removes hydrogen from the six hydroxyl groups of myo-inositol using phosphoric acid. It is mainly composed of a compound called esterified phytic acid, and the present inventors found that all 12 hydroxyl groups of this compound are reactive with metals, and among them, 1-
The hydroxyl group of phosphoric acid at the and 4-positions is the most active, followed by the hydroxyl groups at the 2-1, 3-1, 5-1 and 6-1 positions, followed by the hydroxyl groups at the 2-2, 3-2, 5-2 and 6-positions. It was found that the hydroxyl group at the -2 position has low activity. Here, high activity means that it is easy to release H ⁺ and therefore easy to react with metal ions. But 1
As mentioned above, the - and 4- positions have high activity, but the chelating power is weak and unstable, whereas the 6.2-position
and chelation between the 5th and 3rd positions is strong,
The present invention was based on the discovery that it is both stable and stable. The present invention can form a strong hydrophilic film, has a fast film formation rate, does not deteriorate over time due to light or heat, and therefore does not cause scumming on masters or printed matter even when printing in large quantities, and has excellent ink separation properties. This provides a good lithographic printing processing solution. Such processing liquid has the general formula (However, Me and Me are different from each other, Ca, Mg,
Ba, Zn, Al, Co, Ni, Cu, Zr, Fe, B, Mn,
Represents Li, P, Mo or Ti, but Me is Ba or
When Ca, Me never becomes Ca or Ba. ) It is characterized by containing a myo-inositol hexaphosphoric acid derivative shown in the following. Myo-inositol hexaphosphoric acid (phytic acid), which is the basic skeleton of the derivative used in the present invention, has a chair-shaped three-dimensional structure as shown in the general formula above.
It is a compound that has a unique chelating reactivity (chelating power), and the present invention relates to the unique chelating power of myo-inositol hexaphosphoric acid due to its 1- or 4-position phosphoric acid as explained below. This is based on the effective use of hydroxyl groups by inactivating them. All 12 hydroxyl groups of myo-inositol hexaphosphoric acid are reactive with metals. Among them, the 1- or 4-position hydroxyl group is the most active,
Next are the hydroxyl groups at the 2-1, 3-1, 5-1 and 6-1 positions, and the hydroxyl groups at the 2-2, 3-2, 5-2 and 6-2 positions have low activity. High activity here means that it is easy to release H ⁺ and therefore easy to react with metal ions. Furthermore, although the 1- and 4-positions have high activity as mentioned above, their chelating power is weak and unstable. The positions where the chelating power is strong and stable are between 6.2 and 5.3. Therefore, in the present invention, in order to utilize this chelating power to the maximum extent possible, the 1-
and the 4-position hydroxyl group is inactivated with a metal atom so that it does not react with metal ions. The thus inactivated myo-inositol hexaphosphoric acid, that is, the myo-inositol hexaphosphoric acid derivative of the present invention, has the properties as a processing liquid for lithographic printing, that is, it has an appropriate solubility in a weakly acidic aqueous solution (PH = 4.5 to 6.0). has
In addition, the chelate produced by the reaction with metal ions has the property of not being dissolved in the aqueous solution. A treatment solution containing such a myo-inositol hexaphosphate derivative (PH = 4.5 to 6.0)
When applied to, for example, a ZnO-based electrophotographic original plate, a reaction occurs selectively between the Zn ⁺⁺ of ZnO exposed on the plate surface and the 6/2 and 3/5 positions of the myo-inositol hexaphosphoric acid derivative. A chelate that is hydrophilic and insoluble in a weakly acidic aqueous solution is produced on the plate surface, thereby improving printing durability and ink separation. The myo-inositol hexaphosphate derivatives of the present invention can be easily synthesized by known methods, and specific examples thereof include myo-inositol 2,3,5,6-
Phosphoric acid-1-magnesium phosphate-4-calcium phosphate salt (compound No. 1), myo-inositol-2,3,5,6-phosphoric acid-1-barium phosphate-4-zinc salt (compound No. .2), myo-inositol-2,3,5,6-phosphate-1-phosphate barium-4-aluminum phosphate salt (compound
No.3), myo-inositol-2,3,5,6-
Phosphoric acid-1-copper phosphate-4-magnesium phosphate salt (compound No. 4), myo-inositol-2,
3,5,6-phosphoric acid-1-zirconium phosphate-
4-cobalt phosphate salt (compound No. 5), myo-inositol-2,3,5,6-phosphoric acid-1-boron phosphate-4-manganese phosphate salt (compound
No.6), myo-inositol-2,3,5,6-
Phosphoric acid-1-calcium phosphate-4-molybdenum phosphate salt (compound No. 7), myo-inositol-
2,3,5,6-phosphoric acid-1-tungsten phosphate-4-iron phosphate salt (compound No. 8), myo-inositol-2,3,5,6-phosphoric acid-1-magnesium phosphate -4-Barium phosphate salt (compound
No.9), myo-inositol-2,3,5,6-
Phosphate-1-barium phosphate-4-zinc phosphate salt (compound No. 10), myo-inositol-2,3,
5,6-phosphoric acid-1-magnesium phosphate-4-
Examples include titanium phosphate salt (compound No. 11). In addition, the processing solution of the present invention includes acids such as citric acid, phosphoric acid, phytic acid, malonic acid, adipic acid, tannic acid, tartaric acid, sulfuric acid, and glycolic acid; bases such as ammonium phosphate and alkali metal phosphate. , borates, caustic soda, caustic potash, ammonia, citrates, tartrates, etc.; metal salts such as aluminum alums, sulfates, nitrates; lubricants such as gum arabic, CMC, pectin, polyvinylpyrrolidone, polyvinyl alcohol, methyl Vinyl ether to maleic anhydride copolymers, alginic acid, alcohols, glycerin, etc.; amines such as triethanolamine and triethylamine as anticorrosive agents; sodium dehydroacetate, salicylic acid, etc. as preservatives can be added. Examples and comparative examples are shown below. Example 1 Compound No. 1 50g Water 1000ml Example 2 Compound No.2 20g Water 1000ml 10g of citric acid was adjusted to pH=4.0 with KOH. Example 3 Compound No. 3 20g Water 1000ml Glycerin 40g was adjusted to PH=3.0 with triethanolamine. Example 4 Compound No. 4 50g Water 1000ml Malonic acid 10g was adjusted to pH=4.5 with NaOH. Example 5 Compound No. 5 20g Water 1000ml Propylene glycol 50g was adjusted to pH=5.0 with NaOH. Example 6 Compound No. 6 50 g Water 1000 ml Example 7 Compound No. 7 30 g Water 1000 ml Example 8 Compound No. 8 20 g Water 1000 ml Isopropyl alcohol 50 g was adjusted to pH=4.0 with KOH. Example 9 Compound No. 9 50g Water 1000ml Comparative Example 1 Phytic acid 50g Water 1000ml Comparative Example 2 Phytic acid monocalcium salt 50g Water 1000ml was adjusted to pH=4.0 with NaOH. The above treatment solution was applied at a coating speed of 100 mm/sec to a zinc oxide electrophotographic original plate or a direct plate (drawn with magic ink, ballpoint pen, and type) that had been made in advance using a commercially available plate-making machine, and after desensitization treatment, a commercially available Printing was carried out using an offset printing machine. The results are shown in the table below. Note that water was used as a dampening solution during printing.

[Table] Ink separation property was determined by using the original plate for printing 100 sheets after desensitizing it, leaving it for 10 minutes, and performing offset printing again.The ink attached to the background of the master was separated by the idle rotation of the printing roller It was calculated as the time it takes to do so.

Claims (1)

[Claims] 1. General formula (However, Me and Me are different from each other, Ca, Mg,
Ba, Zn, Al, Co, Ni, Cu, Zr, Fe, B, Mn,
Represents Li, P, Mo or Ti, but Me is Ba or
When Ca, Me never becomes Ca or Ba. ) A lithographic printing processing liquid containing a myo-inositol hexaphosphoric acid derivative represented by: