JPS6015478B2 - Plate cleaning agent for lithographic printing plates - Google Patents

Description

[Detailed description of the invention] The present invention relates to a plate surface cleaning agent for lithographic printing plates.

Lithographic printing is a printing method that skillfully takes advantage of the essentially immiscible nature of water and oil. It consists of a receiving area, the former being a non-image area and the latter being an image castle. Therefore, if this balance is disrupted, for example, if the hydrophilicity of a non-image area deteriorates for some reason, ink will adhere to that area, resulting in so-called "background stains". There are various causes of scumming, but a typical one is that if the hydrophilic calendar (non-image castle) is left exposed to the atmosphere without being covered after development, it may appear in spots or on the entire surface during printing. Ink may adhere. A similar phenomenon can also be seen during printing, when there is a problem with the printing press or when the printing press is stopped during a break. Therefore, it is customary for those skilled in the art to apply gum fluid when stopping a printing press. If a lipophilic substance is attached to the hydrophilic layer of the bare layer and left unattended, the area becomes oil-sensitized and becomes dirty. The aircraft is also responsible for the appearance of fingerprint marks on printed matter. Furthermore, a non-image cast with scratches may be used, and in this case, ink may become clogged in the scratches and gradually become oil-sensitized, resulting in stains. There has been a strong desire for an excellent plate surface cleaning agent (sometimes called a plate cleaner) to remove the ink and restore the hydrophilicity of the area in such cases. A number of types of plate cleaners have been provided for this purpose.

Plate Cleaner CN manufactured by Fuji Photo Film ■ is one of them, and its desensitizing effect is extremely high. However, because the composition has alkali IJ properties, some alkaline-developable photosensitive lithographic printing plates, such as the o-quinonediazide type described in Japanese Patent Publication No. 43-28403, U.S. Patent No. 304,612, etc. When used in a positive-working lithographic printing plate using a photosensitive material or a negative-working lithographic printing plate using a resin having an acidic group as described in JP-A-46-13314, the image area may be dissolved or ink may adhere. The quality may deteriorate. In addition, the plate cleaner using Hakama acid described in U.S. Pat. No. 3,489,561 has a strong effect of corroding metal supports, so it is usually
A hydrophilic layer (formed by a permanent hydrophilic treatment as disclosed in U.S. Pat. No. 2,714,066, for example) that is applied to the surface of a support of a lithographic printing plate that has been previously given photosensitization. It is not suitable for metal supports as it destroys the coated layer) and causes stains. Generally, if dirt occurs during printing,
The method used is to first remove the ink on the plate surface with an ink cleaning agent, and then treat it with a desensitizing agent, but since the above-mentioned plate surface cleaning agent is used as a degreasing agent after cleaning the ink, it is difficult to clean the plate surface. The treatment consists of two steps and is complicated.

Therefore, in recent years, plate surface cleaners have been developed that have both ink cleaning action and desensitizing action. Plate cleaner CU manufactured by Fuji Photo Film ■ belongs to this category and is acidic and emulsified. The plate surface cleaning agent exhibits its effect on all lithographic printing plates, but its anti-greasing ability is not as strong as that of plate cleaner CN. In particular, it has a weak ability to suppress dirt generated in the hydrophilic layer (non-image area). The causes of stains that occur during normal printing can be roughly divided into the following: adhesion of oil-sensitive substances, destruction of the hydrophilic layer due to scratches, etc., deterioration of the hydrophilic layer due to oxidation, etc., and removal of the oil-sensitive substance and the altered hydrophilic layer. At the same time, it is desirable to process the area with a processing chemical that has the ability to newly form a hydrophilic layer in that area, and which does not damage the image.

An object of the present invention is to provide a printing plate cleaner having the above performance.

As a result of various studies, the inventors of the present application have achieved by using an aqueous solution of sulfamic acid as a plate cleaning agent, and the usable range of sulfamic acid is 0.1 to 15% by weight based on the plate cleaning agent. More preferably it is in the range of 0.5 to 1 weight percent.

The plate surface cleaning agent of the present invention mixes and uses a hydrocarbon thread solvent that has the effect of dissolving lithographic printing ink.
It can be made into a more user-friendly form.

As the hydrocarbon solvent, a petroleum fraction having a boiling point in the range of 120 to 320 qo and capable of dissolving printing ink (used for washing printing ink) is preferable. The hydrocarbon solvent is preferably used in an amount of 10 to 6% by weight, more preferably 20 to 4% by weight of the plate surface cleaner. It is desirable that the sulfamic acid aqueous solution and the hydrocarbon solvent can be in an emulsified or suspended state, which is highly effective. Even if the two are mixed and shaken, the dispersion state does not persist, so the dispersion state can be improved by adding a hydrophilic protective colloid substance or a surfactant.

These hydrophilic protective colloid substances or surfactants can be added to the plate cleaning agent either singly or in combination. Effective hydrophilic protective colloid substances include water-soluble dextrins, gum arabic, alginates, and cellulose derivatives (e.g., carpoxycetyl cellulose, methyl cellulose, hydroxyethyl cellulose).
Natural polymer substances such as or modified products thereof, polyvinylpyrrolidone, polyacrylamide, or copolymers thereof, acrylic acid copolymers, vinyl acetate/maleic anhydride copolymers,
Synthetic polymeric substances such as styrene/maleic anhydride copolymer are used, and the preferable amount added is 0.000% to the plate surface cleaner.
The range is from 5 to 24% by weight, more preferably from 1 to 2% by weight. As the surfactant, anionic surfactants or nonionic surfactants can be used. Examples of anionic surfactants include aliphatic alcohol sulfate ester salts,
Fatty alcohol phosphate ester salts, dibasic fatty acid ester sulfonate salts, fatty acid amide sulfonate salts, alkylaryl sulfonate salts, formaldehyde condensation naphthalene sulfonate salts, etc. are used. As the nonionic surfactant, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxypropylene polyoxyethylene ethers, etc. are used. Two or more surfactants can also be used in combination.

The amount used is not particularly limited, but the preferred range is 0.01 to 1 weight percent of the plate cleaning agent. In addition to the above components, wetting agents, detergents, pigment pumice, etc. can also be added if necessary. The present invention may further contain at least one mineral acid or organic acid.

The content is preferably in the range of 0.1 to 1% by weight of the plate surface cleaner. Key acids include nitric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and hydrofluoric acid, and organic acids include organic carboxylic acids such as hakamaic acid, acetic acid, malonic acid, citric acid, tartaric acid, malic acid, lactic acid, and levulinic acid, or benzene. Sulfonic acid, toluenesulfonic acid, xylene sulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and the like are useful. Next, the present invention will be specifically explained using examples.

The invention is not limited to this example.
Example 1 40 parts by weight of 140-layer gum arabic was mixed with 22 parts by weight of water, and 3 parts by weight of sulfamic acid was added thereto and dissolved in a pestle.

Next, 1 part by weight of 85% phosphoric acid polyethylene glycol oleyl ether [manufactured by Daiichi Kogyo Seiyaku ■, Noigen ET-12]
0] 2 parts by weight 10 parts by weight of glycerin and 0.5 parts of magnesium nitrate were mixed and dissolved to prepare a solution A. On the other hand, a block copolymer of polypropylene glycol and polyethylene glycol ether [first
2 parts by weight of Epan-450 manufactured by Kogyo Seiyaku ■ was dissolved to obtain liquid B.

Next, slowly drop B solution into the A solution prepared as above and disperse it, then use FISHERSCI
An emulsion was prepared using a homogenizer manufactured by ENTIFIC.

Next, a positive type PS version Super Positive Glencoat manufactured by Fuji Photo Film ■ was made into a plate according to the specified method, and then a portion of the non-image area was scratched with a needle and oleic acid was rubbed therein.

The printing plate damaged in this way/Idelberg G
When I printed it with a TO type printing machine, the positive part was dirty.

After printing 10 sheets, the dirty areas were wiped with the cleaning agent prepared as described above, and 30,000 sheets were printed. No stains appeared after wiping with cleaning solution. Example 2 A plate cleaning agent was prepared by mixing and emulsifying Liquids C and D having the following formulation.

C liquid water --Ichiro. Wide weight section PVA
GH-17 [manufactured by Nippon Gosei ■] - 112 parts by weight of sulfamic acid --4. xylene glycol (parts by weight of animal) --10. parts by weight of boric acid
---1. Part by weight of Alkylnaphthalene sulfonate [Verex NB manufactured by Kao Atlas ■
-L] ---1. Part by weight of oxyethylene oxypropylene block polymer [Kao Atlas Emulgen 9
03] 1112. parts by weight ○Liquid Solvent-K [manufactured by Nippon Oil ■] -112 parts by weight Sorbitan fatty acid ester [Kao Atlas ■Span-8
0] --- 2 parts by weight After making a plate in the same manner as in Example 1 and printing 500 sheets, the scratched and stained portions of the plate were treated with a plate cleaning agent prepared by the above method, and after washing with water, 150 sheets were printed. It was dried in a dryer at 0 for 15 minutes.

When the print was then printed again, the portions that had not been treated with the plate cleaning agent were slightly smudged.

This experiment confirmed the desensitizing effect of the plate surface cleaner.

Example 3 A plate cleaning agent was prepared by mixing and emulsifying solutions E and F having the following formulation.

E liquid water---56. Part by weight of carboxy methyl cellulose [Celogen 7A manufactured by Daiichi Kogyo Yakuhin ■] ---2. Part by weight of ethylene glycol --10. parts by weight of sulfamic acid
---3.5 parts by weight phosphoric acid (85%)
---1. parts by weight of nickel nitrate
--- 0.5 parts by weight polyethylene glycol nonyl phenyl 17 l [Noigen EA manufactured by Daiichi Kogyo Seiyaku ■] 1112. Part by weight of talc --3. Part by weight of F-Liquid Solvento K [manufactured by Nippon Oil Co., Ltd.] 11120. Part by weight of polyethylene glycol sorbitan monostearate [
Solgen Tw manufactured by Daiichi Kogyo Seiyaku column]--2. By weight, a positive type plate Ozazol P-4 manufactured by Seishi Dokuri Co., Ltd. was plate-made according to the specified method and tested in the same manner as in Example 1, and the same effect was obtained.

Example 4 A plate cleaning agent was prepared by mixing and emulsifying liquid G and liquid H having the following formulation.

G liquid water --55. Part by weight of carboxy methyl cellulose [Celogen-7A manufactured by Daiichi Kogyo Yakuhin ■] --2. Part by weight of triethylene glycol --- 10. parts by weight of sulfamic acid
---5. Part by weight of nitric acid
--0.5 part by weight magnesium nitrate
---0.5 parts by weight Silica powder [Syroid #24 manufactured by Fuji Devson Chemical ■ 1-3.
Part by weight of polypropylene glycol/polyethylene glycol ether block copolymer (Copan-420 manufactured by Daiichi Kogyo Seiyaku ■)---2. parts by weight of kerosene
---20. Part by weight of Solpitan monostearate (Daiichi Kogyo Seiyaku ■Solgen 50)
---2. Part by weight of Fuji Photo Film's negative type PS version Super Negatip Glencoat was made using the specified method and left at a temperature of 100°C for 30 minutes without gumming. When printed on an Idelberg GTO printing machine, the entire surface was printed. Dirt occurred on the surface.

The printing press was stopped, the bottles were treated with a bottle surface cleaner prepared according to the above recipe, and printing was performed again. The area treated with plate cleaning agent is 3.
No stains occurred even after printing 10,000 copies.

Example 5 A plate cleaning agent was prepared by mixing and emulsifying Solution 1 and Solution J having the following formulation.

1 Liquid water 58.5 parts by weight Propylene glycol 10. Part by weight of methylcellulose 1. parts by weight of sulfamic acid 4. parts by weight of sodium sulfate
1. Part by weight of 85% phosphoric acid
0.5 parts by weight polyethylene glycol decyl phenyl ether [manufactured by Daiichi Kogyo Seiyaku ■/Eigen EA-83] 2. Part by weight of naphthalene sulfonic acid formalin condensate [Kao Atlas Demo-P]
1. Part by weight J liquid kerosene
20. Part by weight of sorbitol oleic acid monoster [
Nissan Nonion OP-80 manufactured by NOF■ 2. After exposing and developing a negative type PS plate negative grain coat manufactured by Fuji Photo Film ■, it was dried for 30 minutes in a dryer kept at 100℃ (This is a method that deviates from common sense in terms of handling conditions, but as a method to generate dirt. When these conditions were selected), printing was then performed using a Heidelberg GrO type offset printing machine, and slight staining was observed on the entire surface.

After printing 50 sheets, printing was stopped, and a cellulose sponge was soaked in a liquid obtained by mixing and emulsifying liquids 1 and J having the above composition, spread over the entire plate surface on the printing machine, and rubbed it in with gentle force.

Claims (1)

[Scope of Claims] 1. A plate cleaning agent for lithographic printing plates, which is a suspension or emulsion of an aqueous sulfamic acid solution and a hydrocarbon solvent that dissolves lithographic printing ink. 2. The plate cleaning agent according to claim 1, wherein the hydrocarbon solvent is a petroleum fraction having a boiling point range of 120 to 320°C. 3. The plate cleaning agent according to claim 1 or 2, wherein the hydrocarbon solvent is contained in an amount of 10 to 60% by weight of the plate cleaning agent. 4. A suspension or emulsion of an aqueous sulfamic acid solution and a hydrocarbon solvent that dissolves lithographic printing ink, further containing at least one selected from the group consisting of a hydrophilic protective colloid substance and a surfactant. A plate surface cleaning agent for lithographic printing plates characterized by: