JP2733495B2 - Desensitizing solution for lithographic printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desensitizing solution for lithographic printing, and more particularly to a desensitizing solution for lithographic printing of an electrophotographic planographic printing plate, a silver salt printing plate, a PS plate, etc. It is about.

[0002]

2. Description of the Related Art In lithographic printing, ie, offset printing, a lipophilic image area is formed by applying a desensitizing solution onto a printing original plate on which an image area has been formed by plate making to form a hydrophilic layer on the non-image area. Is a printing method in which an oil-based ink is adhered to transfer the ink in the image area to paper. Among the printing original plates used in this printing method, an electrophotographic lithographic printing original plate in which a photosensitive layer in which a photoconductive powder such as zinc oxide is dispersed in an adhesive resin is coated on a support such as paper, The plate is made by electrophotography consisting of a process of charging, exposure and development, and lipophilic toner particles in a developer are attached to form an image portion on the plate surface,
Then, a hydrophilic substance is formed by the desensitizing agent in the processing liquid and the photoconductive powder in the surface layer by applying the desensitizing processing liquid to form a hydrophilic layer on the non-image portion of the original plate.
Thus, the original plate having the lipophilic portion and the hydrophilic layer is supplied to a printing press and used for lithographic printing.

The main components of the conventional desensitizing solution are roughly divided into cyan-based substances and non-cyan-based substances. Cyanide-based substances are those in which cyan ions are present in the molecule as an inorganic complex, and ferrocyanides and ferricyanates are widely used. These have strong desensitizing power and satisfy printing characteristics comprehensively. However, these cyanide substances are unstable to light and heat, discoloring and sedimenting, and desensitizing power decreases with time.Also, although they are stable and harmless to the human body, ultraviolet rays and It is feared that it is decomposed by various environmental conditions such as irradiation of radiation, and harmful cyanide alone is released to cause pollution. In addition, printing on neutral paper or printing with a quick-drying color ink tends to cause phenomena such as stains on printed matter and emulsification of the ink, which poses a practical problem.

On the other hand, some non-cyanide substances use inorganic acid salts, but phytic acid, which is an organic acid, and salts thereof are widely used. Phytic acid or a salt thereof is excellent in environmental safety and workability, but has a problem in that it is difficult to set conditions at the time of printing due to weak desensitizing power alone, and the printed matter is easily stained. In order to solve such problems of phytic acid, a combination with a metal complex of aminocarboxylic acid or the like (Japanese Patent Publication No. 2-39397) or a combination with a hexametaphosphate (Japanese Patent Publication No. 62-7597) has been tried. However, no satisfactory effect has been obtained yet.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a desensitizing solution for lithographic printing which has a good desensitizing power and has no environmental problems. It is.

[0006]

According to the present invention, a desensitizing solution for lithographic printing mainly containing phytic acid or a salt thereof contains a polyether polyamine represented by the following general formula or a derivative thereof. Is a desensitizing solution for lithographic printing characterized by the following.

Embedded image ＫIn the above formula, k, m, x, y are integers of 1 or more, R ₁
Is H or C _n H _2n R ₂ . However, n is an integer of 1 or more, and R ₂ is represented by H, NR ₃ R ₄ (R ₃ and R ₄ are H or an alkyl group), Cl, F, I, Br, OH, COOH or CONH ₂ . ｝

The polyether polyamine represented by the above general formula or a derivative thereof used in the present invention is a compound having a high cationic property, and has a large desensitizing ability by reacting with phytic acid or a salt thereof. It has a remarkable effect that it can be improved. In the present invention, a polyether polyamine having a colloid equivalent value of 3 or more in a pH range of 3 to 10 as a measure of cationicity has good reactivity with phytic acid or a salt thereof and has a better desensitization property. It is preferably used because it has good properties. In addition, as the compound having such a cationic property, a quaternary ammonium chloride-modified polyether polyamine in the structure represented by the general formula can also be used.

In the present invention, it is necessary that the above polyether polyamine or its derivative is water-soluble, and in the above general formula, k = 2 to 50 and m = 2
It is preferably from 1 to 10 for obtaining good water solubility. Further, in order to achieve the excellent desensitizing property which is the object of the present invention, the ratio of x and y is such that x: y = 1: 1 to 4:
It is preferably 1. Furthermore, the molecular weight is 1
It is preferably from 1,000 to 1,000,000, particularly preferably 1,000.
~ 1,000,000.

The phytic acid and its salt used in the present invention are also known as inosit hexaphosphate,
Conventionally used ones are generally used. Since these compounds are acidic and form a salt with a metal, they can be used as a desensitizing agent. In addition, as a phytate, an alkali metal salt, an ammonium salt, an amine salt, etc. are mentioned. The amount of phytic acid or a salt thereof in the desensitizing solution of the present invention is 1 to 200 g / l, and the amount of polyether polyamine or a derivative thereof is 0.01 to 2 g / l.
0 g / l, and more preferably 0.1 to 5.0 g / l.

When phytic acid is used in the present invention,
Since phytic acid and polyether polyamine may combine with each other to form a water-insoluble compound, a buffer may be added as necessary. Examples of the buffer used include sulfonic acid compounds such as ammonium sulfate, methanesulfonic acid or a salt thereof, ethanesulfonic acid or a salt thereof, benzenesulfonic acid or a salt thereof, toluenesulfonic acid or a salt thereof, xylenesulfonic acid or a salt thereof, and the like. Is mentioned.

[0011] The desensitizing solution of the present invention may contain the following components. That is, pH
Inorganic acids, organic acids and salts thereof are used alone or in combination as a regulator or a pH buffer. Examples of inorganic acids include phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid, and examples of organic acids include formic acid, acetic acid, butyric acid, valeric acid, lactic acid, tartaric acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, and the like.
Maleic acid, phthalic acid, citraconic acid, itaconic acid, fumaric acid, tricarbaric acid, glycolic acid, propionic acid, thioglycolic acid, malic acid, citric acid, gluconic acid, pyruvic acid, glycolic acid, salicylic acid, adipic acid, hydro Acrylic acid, glyceric acid, P-toluenesulfonic acid and the like. These salts include alkali metal salts, ammonium salts, amine salts and the like.

Also, as a wetting agent, wetting agents such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, gum arabic, carboxymethyl cellulose, acrylic polymer, methanol, ethanol, iso and normal propyl alcohol, triethanolamine, etc. Can be. In addition, salicylic acid, phenol,
Phenol butyl parabenzoate, sodium dehydroacetate, 4-isothiazolone-3-one compound and the like can be added. In addition, EDTA, sodium nitrite, dicyclohexylammonium nitrite and the like can be added as a rust preventive.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” means “parts by weight” unless otherwise specified. Example 1 After blending with the following composition and thoroughly mixing and dissolving, about 40 parts of an aqueous ammonia solution (50%) was added to adjust the pH to 4.0 to prepare a desensitizing solution of the present invention. - phytic acid 50 parts polyether polyamines 1 part _{- (CH 2 -CH 2 -O)} X - (CH 2 -CH 2 -NH) y - ( number average molecular weight of 10,000, x: y = 2: 1 ) · 1000 parts of distilled water

Example 2 After blending with the following composition and thoroughly mixing and dissolving, about 40 parts of an aqueous ammonia solution (50%) was added to adjust the pH to 4.0, and the desensitizing solution of the present invention was added. Produced. 100 parts of phytic acid 5 parts of polyether polyamine-[(CH ₂ ) ₃ -O] _X- [CH ₂ -CH ₂ -N (CH ₂ CH ₂ NH ₂ )] _y- (number average molecular weight 10,000, x : Y = 2: 1) ・ 54 parts of ammonium sulfate ・ 1000 parts of distilled water

Example 3 In Example 1, the polyether polyamine was represented by the structural formula-[(CH ₂ ) ₁₂ -O] _x- (CH ₂ -CH ₂ -N
H) A desensitizing solution of the present invention was prepared in the same manner as in Example 1 except that the compound represented by _y- (number average molecular weight 100,000, x: y = 2: 1) was used. Example 4 In Example 1, a polyether polyamine having a structural formula of-[(CH ₂ ) ₁₈ -O] _X- (CH ₂ -CH ₂ -N
H) A desensitizing solution of the present invention was prepared in the same manner as in Example 1 except that the compound represented by _y- (number average molecular weight: 500,000, x: y = 4: 1) was used.

Example 5 In Example 1, a polyetherpolyamine having the structural formula-[(CH ₂ ) ₂₈ -O] _x- (CH ₂ -CH ₂ -N
H) _y- (number average molecular weight 1,000,000, x: y = 4: 1)
A desensitizing solution of the present invention was prepared in the same manner as in Example 1 except that the compound represented by the formula (1) was used. Comparative Examples 1 to 4 After blending with the composition shown in Table 1 and mixing and dissolving well, about 40 parts of an aqueous ammonia solution (50%) was added to adjust the pH to 4.0.
To prepare a desensitizing solution for comparison.

[Table 1]

An electrophotographic lithographic printing plate precursor of a commercially available zinc oxide-resin dispersion system was made by electrophotography, and the desensitizing solution of Examples 1 to 5 and Comparative Examples 1 to 4 was used to prepare an automatic plate made by Ricoh Company. The planographic plate was etched by an etching apparatus to obtain a printing plate for offset printing. Further, a fountain solution obtained by diluting the desensitizing solution used for etching by 5 times with water was supplied to a Ryobi thin flow lithographic printing press, and printing was performed by the printing press. At this time, a quick-drying color ink (F gloss ultramarine, manufactured by Dainippon Ink and Chemicals, Inc.) was used as the ink, and neutral paper (TomoEliver, manufactured by Tomagawa Paper) was used as the printing paper.

In the printing test, continuous printing of 3000 sheets was performed, and the inking property, resolution, background stain,
Confirmation of halftone dot blurring, emulsification on a printing press roller, and generation of a roller strip were observed, and the results are shown in Table 2.

[Table 2]

The evaluation method of the printing test is as follows. <Adhesiveness> The density of the solid portion of the ink transfer portion of the printed matter was measured with a Macbeth densitometer RD-914. <Resolution> The reproducibility of the resolution test chart of the printed matter was visually evaluated using a loupe in each of the vertical direction and the horizontal direction, and represented by a numerical value of the resolution (the number of lines per 1 mm). The larger the numerical value, the higher the resolution. <Background Soil> As a desensitizing property, the stain of the printed matter with the ink in the untransferred portion of the ink was visually evaluated. ：: no stains Δ: slight stains X: considerable stains <dot blur> The reproducibility of halftone dots corresponding to an area ratio of 80% of the dot test chart of the printed matter was observed using a loupe. ：: good ×: bad <Emulsification> The occurrence of abnormal emulsification at the roller portion of the printing machine was visually evaluated. ：: No occurrence Δ: Slight occurrence X: Considerable occurrence <Roller strip> The ink stripping phenomenon at the roller portion of the printing press was visually evaluated. ○: No occurrence ×: Occurrence

As is clear from Table 2, when the desensitizing solution according to the present invention is used, it has good inking property even after continuous printing of 3000 sheets, has no background stain on printed matter, and has other printing characteristics. Was also confirmed to be good. In addition, no emulsification or roller strip occurred in the printing machine. On the other hand, the desensitizing treatment liquids for comparison all had poor inking property and background stain, and further caused some problems, so that satisfactory printing characteristics could not be obtained.

[0021]

The desensitizing solution for lithographic printing of the present invention comprises:
Since it is a non-cyanic treatment liquid, it has no problem of environmental pollution and has good desensitization characteristics, so that practically good printing characteristics can be obtained and excellent printed matter can be provided.

Claims (1)

(57) [Claims] 1. A lithographic printing desensitizing solution containing phytic acid or a salt thereof as a main component, comprising a polyether polyamine represented by the following general formula or a derivative thereof: Fat treatment liquid. Embedded image ＫIn the above formula, k, m, x, y are integers of 1 or more, R ₁
Is H or C _n H _2n R ₂ . Here, n is an integer of 1 or more, R ₂ is H, NR ₃ R ₄ (R ₃ and R ₄ are H or an alkyl group), Cl, F, I, Br, OH, COOH or CONH ₂ . ｝