JPS634994A - Concentrated fountain solution for plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to acidic fountain solutions useful in lithographic offset printing processes.

The conventional technique of lithography is known. - Generally, this method is printing from flat plates or cylinders (usually anodized aluminum) without surface relief, due to the different properties of the image and non-image zones of the surface for printability. In lithographic printing, the image to be reproduced is applied to a plate in such a way that the non-image zones are rendered hydrophilic, while the image zones are hydrophobic, in one of several known methods.

A widely practiced technique uses light sensitizing coatings for this purpose. Following imagewise exposure of the light sensitized coating to light, the latent image is developed and a portion of the coating is removed from the root. The plate is then treated with a desensitizing solution (a so-called finishing or preservation composition) to render the plate hydrophilic in the zones where the light sensitizing coating has been removed. During the actual printing process, a fountain solution is used on the surface of the plate. The fountain solution keeps all parts of the surface that do not contain the hydrophobic image moist. Furthermore, the fountain solution protects the plates from dirt. That is, it prevents non-image zones from becoming at least partially ink receptive. The fountain solution can also be tailored to gradually attack the plate surface, keeping the lines sharp enough to protect against rapid wear. In the conventional type, the fountain solution is applied to the plate with one or several rollers. At least one ink roller coated with an oil-based printing ink contacts the entire surface of the plate, but deposits the lithographic ink only in the image zones. This is because the hydrophilic non-image zones repel ink. Therefore, for each impression obtained during a run, the lithographic plate is first wetted with fountain solution and then coated with lithographic ink. Optionally, at least a portion of the fountain solution and the oil-based ink are applied simultaneously to the plate using a roller. In this last type, another roller, usually smaller in diameter than the first roller, may contact the plate and at the same time distribute the ink evenly. Finally, the ink of the image is transferred directly to the paper sheet or other receiving surface to be copied, or to a rubber offset blanket or synthetic material, which in turn transfers the print to the final copying surface.

The fountain solution is prepared from the fountain corrosion concentrate by adding additional water and often about 10 to 60 volumes of isozolobyl alcohol. Acid corrosion fountain concentrates known in the literature contain water-soluble resins or gums, such as gum arabic or cellulose gum, and may also contain acid corrosion agents, buffers and wetting agents.

Acidic fountain solutions are generally prepared to achieve a variety of effects. Using hydrophilic colloids, e.g. gum arabic,
The non-image areas of the plate remain hydrophilic during the printing process. Additionally, acidic etchants and ink repellents may be included to maintain clarity in non-image areas. A surfactant or a combination of a surfactant and an alcohol, such as isozolopyl alcohol, is used to lower the interfacial tension of the solution to about 60-4
High wetting of the plate and roller surfaces is obtained down to the 0 dynes/crIL2 range. This property allows the use of metal salts such as nitrates, chromates, etc. and/or alcohols or glycols to maintain the hydrophilicity of the non-imaging plate surface in the excess amount necessary to maintain the hydrophilicity of the non-imaging plate surface without the use of surfactants. It can also be obtained by using one type or a combination of several types.

The use of surfactants of such composition can lead to problems with foaming or emulsification of the printing ink during the printing process. Furthermore, fountain solutions containing surfactants tend to wet printed paper more than solutions without surfactants, especially when colors are used. This makes the paper spongy and causes the printing ink to spread through the paper, resulting in a blurry image.

The use of higher than required concentrations of colloids results in smearing or plinting of the plate and increases the tendency of the printing ink to emulsify. The use of salts, such as nitrates, and excessive amounts of colloids (gum arabic) further complicates the problem of silindering due to the tendency of these substances to complex with gum arabic, resulting in gum arabic salts, which usually results in cylindrical plate loading.

The use of large amounts of volatile solvents, such as isopropyl alcohol, in the fountain solution reduces the solubility of other components present in the solution, which stick to the surface of the roller or plate. Furthermore, isopropyl alcohol is undesirable. This is because it is toxic and flammable and has a low vapor pressure, which results in rapid evaporation.

(8) Alternative methods of such preparation that do not contain isopropyl alcohol have been proposed in the literature. U.S. Pat. No. 4,060,417 describes a fountain solution based on a mixture of fatty acids, -valent metal hydroxides, gum arabic, -valent metal iodides and water. US Pat. No. 3,877,372 describes a solution containing a mixture of ethylene glycol monosothyl ether and at least one of hexyl glycol and ethylene glycol. U.S. Pat. No. 4,278,467 discloses a mass standard corrosive concentrated fountain solution containing isopropyl alcohol and principally n-hexoxyethylene glycol, n-hexoxydiethylene glycol, 2-ethyl-1,3-hexanediol, n- −
Butoxyethylene glycol acetate, n-butoxydiethylene glycol acetate, 3-butoxy-2-
Fountain solutions based on dilute mixtures of one or more compounds selected from the group of nonionic compounds consisting of nolopanol and mixtures thereof are described, said compounds having the characteristic of having a molecular weight of 100 to 300 gm mol. Although these and similar preparations have had some success, it has been found that they are not readily compatible with anodized aluminum based printing plates, particularly electrochemically etched plates.

This is because the non-image areas of the plate are not kept sufficiently clean during the printing process and become contaminated.

The problem that the invention seeks to solve is not only preventing fouling or cylindrical printing of printing plates, especially electrochemically roughened plates of anodized aluminum, but also provides other advantages, such as rapid winding of the printing press, printing process Non-foaming of the solution during
Resistance to solution residue sticking to transfer rolls or roll covers;
Improved print quality, reduced wetting tendency of printing paper,
There is a great need for improved fountain solutions for offset printing that provide rapid ink drying and improved ink/water balance.

Means for Solving the Problem This objective is primarily aimed at (a) producing a hydrophilic rubber that forms a water-soluble film;
(c) about 0.5-15% by weight of 2-ethyl-1,6-hexanediol (e) about 0.02-15% by weight of a pH/buffer adjuster consisting of a mixture of an organic acid and an alkali metal salt of an organic acid, 0) about 5-62 metal nitrates, and (f) about 0 phosphoric acid. This is achieved by obtaining a concentrated fountain solution consisting of an aqueous solution containing .02 to 2.75% by weight of the mixture.

Additionally, the concentrate may contain a fungicide and a dye, and is prepared to contain about 65 to 65% by weight of water, and is suitable for further dilution with water, and contains at least about 99% by weight of water. %, preferably about 99.1-99.9% by weight of water and correspondingly 0.1-0.9% by weight of non-aqueous components. The fountain solution most preferably contains about 0.6-0.7% by weight of non-aqueous composition. Furthermore, the composition of the solution is characterized by the term "consisting mainly of 6", which indicates that the solution has the above relationship and does not have an amount of surfactant and/or isozorobyl alcohol.

The fountain solution of the invention is characterized by having an interfacial tension (measured with an interfacial tensiometer) in the range of about 30-40 dynes per i. This is obtained without adding surfactants and/or isopropyl alcohol to the composition. Although the fountain solution generally has a low solids content and can be used on printing plates at lower concentrations than known solutions, sufficient fountain solution, i.e. adequate wetting, action is obtained and staining or cylindering of the printing plate is prevented. be done. Furthermore, this means that the plate wets the printing paper to a small extent and that some solids stick to the plate itself or the Molton roller using the solution.

Water-soluble, film-forming hydrophilic rubbers that can be used in the present invention include arabic yam, gum tragacanth, carboxymethyl cellulose, sodium alginate, carboxymethyl Starch, methylcellulose, and holvinylpyrrolidone, holvinyl alcohol-like dem. The preferred species for the purposes of this invention is gum arabic, and the preferred gum content in the concentrate is about 0.8 to 1.
It is 5.0% by weight.

The fountain solution pH/buffer adjustment system serves a dual role as pH adjustment and plate corrosive agent.

Preferred acids are weak organic acids such as citric acid, ascorbic acid, sulfanilic acid, tartaric acid, lactic acid and acetic acid. A preferred acid is acetic acid. The acid is used at a concentration to give the concentrate a pH in the range of about 2 to 3.5, which when further diluted with water for use as a fountain solution is about 4 to 3.5.
Resulting in a pH in the range of 4.5. Preferred salts for use in combination with the acids are any alkali metal salts of these acids, most preferably the sodium-, potassium- and lithium salts of acetic acid, citric acid and lactic acid. A small amount of an alkali metal salt of phosphoric acid may be mixed with one of the above salts. The mixed combination of acid and salt contains 0.01-2.5% by weight of salt per 0% acid.
．． It may be used in an amount of 0.01 to 12.5% by weight, with the most preferred proportions being 0.075 to 0.75% by weight of salt and 0.01% by weight of acid.
75-6.5% by weight, yielding about 0.8-4.6% by weight relative to the total weight of the aqueous concentrate. These ingredients are
Preferably, in this case, 1 part by weight of the acid salt is about 7 to 1 part by weight of the pure acid.
It is used in a proportion of 3 parts by weight, and 1 mole of salt is used in a proportion of 3 parts by weight of associated water.
Has a molecule.

Other components of the fountain solution are a mixture of water-soluble or water-miscible glycols having 2 to 6 carbon atoms and 2-ethyl-1,3-hexanediol, which serves as a wetting agent and which coats the plate surface. promotes the diffusion of water over the non-image zones of the fountain solution and also retards the flow of printing ink onto the roll surface (molton cover) of the roller used to use the fountain solution. Glycol is ethylene glycol, 1.
2-propylene glycol, 1°3-butylene glycol, neopentyl glycol and hexanediol, with propylene glycol being most preferred. A mixture of one or more of these glycols and 2-ethyl-1,6-hexanediol acts synergistically to maintain the necessary interfacial tension of the fountain solution without containing inzolovyl alcohol, as described above. It turned out that it was possible to obtain Furthermore, this combination inhibits fouling at low water conditions in the printing press that occurs with anodized aluminum plates when one of these polyols is used without any other water conditions.

The concentrate is a glycol/diol mixture of approximately 5.5 to 40
．． 0% by weight (from 5.0 to 25.0% by weight of glycol and correspondingly from 0.5 to 2-ethyl-1,6-hexanediol)
15.0% by weight), glycol/
A preferred concentration is 145-25.5% by weight of diol mixture (12.0-18.0% by weight of glycol and correspondingly 2.5-7% of 2-ethyl-1,3-hexanediol).
．． 5% by weight). These components are preferably used in a ratio of about 2.5 to 3.5 parts by weight of glycol per part by weight of 2-ethyl-1,6-hexanediol.

Other necessary components of the concentrate are water-soluble metal nitrates, which serve as additional corrosive agents for the system.

Suitable salts are the nitrates of magnesium, calcium, cadmium, beryllium, aluminium, tin, zinc, zirconium, nickel, manganese, iron, chromium, copper and lead. Preferred salts are the nitrates of mygan and zinc. The concentration of these salts must be chosen to avoid precipitation on the quality of the printed image. The salt may be used at a concentration of about 5.0-32.0% by weight of the concentrate, with a preferred range of 10.0-18.0%. These weight values are the weights of associated water, which in the case of manganese nitrate is, for example, 6 molecules of water per mole of salt.

An additional component that may be present in the concentrate is phosphoric acid, which serves as a desensitizing agent for the rubber and also acts as a corrosive agent and a PH regulator. The preferred acid is 85
phosphoric acid, used in a wide range of concentrations from about 0.02 to 2.755% by weight of concentrate, preferably from about 0.25 to 0.75% by weight.
It is 75% by weight.

In addition, the concentrate may contain bactericidal agents, such as Dalisil [F] 75 (DOWieil ■), to prevent or inhibit bacteria.
75) [Manufactured by Dow Chemical Company] about 0.01% of the usual concentrate
At a concentration of ~0.4% by weight, preferably about 0.05-0.
It may be contained at a concentration of 125% by weight. Other inert ingredients may be present in the concentrate, such as indicator dyes.

The ingredients are formulated into a concentrate by dissolving them in water, preferably demineralized water. The concentrate preferably contains about 65-65% by weight of water-soluble and water-miscible components dissolved in water, preferably 45-60% by weight.

The fountain solution for the printing press is to mix about 25-90 g of the concentrate with 4 ml of water.
/ (approximately 1 to 6 ounces per gallon of water). The most desirable dilution by the user is approximately 40-60 grams of concentrate per gallon of water.
(1y, ~2 oz).

Examples Example 1 0.095 parts by weight of Dowicil [F] 75 (bactericide) are added to 28.57 parts by weight of demineralized water in a laboratory beaker with constant stirring. When Dalaisil 75 is sufficiently dissolved, gum arabic powder 9
．． Add 5 parts by weight. The solution is heated to 65° C. for 30 minutes with continuous stirring.

After heating for 60 minutes, heating is interrupted and 24.5 parts by weight of demineralized water is added. This is done with continuous mixing and mixing is maintained throughout the process. Then add the next ingredient.

Magnesium nitrate 6 H2O 14,25 [] 1 part by weight Sodium acetate 3H2o O, 130 heavy cod rice acetic acid 1.235 parts by weight Propylene glycol 13.150 parts by weight 2
-Ethyl-1,3-hexanediol 4.975 parts by weight Methyl red dye 0.050 parts by weight Phosphoric acid (85%) 0.545 parts by weight The mixture is stirred until all components are dissolved.

Cool the solution to room temperature and call it the concentrated fountain solution.

Example 2 A fountain solution is prepared by mixing 7.5 ounces of the concentrate from Example 1 with 18.925 gallons of demineralized water.

This solution is placed in one sump of a Miller TP29S2 color printing press (Solution A). In the same way, commercially available fountain concentrates for use in sheet printing machines are produced. This concentrate is a solution containing salt and surfactant using Acibiame as a substrate. Concentrate 2
Add 8.75 ounces of water and isopropanol to 5 gallons of water and isopropanol mixture.

In this case, the improv tool is present in an amount of 25 volumes. Pour this solution into the other reservoir of the printing press (solution B)
. Each reservoir is independently operated, conditioned, and routed to a separate printing unit. Two color printers print two colors on each sheet of paper.

Adjust ink and fountain metering independently. 2 N-5s
0 plate appropriately exposed, developed and finished.

The N-50 plate is a negative working plate that has been roughened with slurry and anodized (Enco Printing Products).
ts), a division of American Hoechst Company, Somerville, NJ). Place both manufactured N-50 plates precisely into the two plate cylinders.

Mead Offset Enameled Stock
0ffset Enamelled 5tock)
The printing process begins by adjusting the supply of both fountains to adjustment point 36 using . Adjust the ink and wet ink specific gravity 1
．． 65 is obtained. Once the ink is balanced, lower the fountain adjustment by adjusting both.

Adjustment continues until the printed sheet shows a clear coloration.

This is a sign of unacceptable print quality. However, it is desirable to keep the fountain adjustment as low as possible to minimize the amount of water supplied. The greater the amount of water applied to the paper, the greater the wetting of the paper and therefore the greater the distortion of the print.

Furthermore, the additional amount of water mixed with the ink can cause emulsification of the ink and/or stripping of the roll, both of which result in poor print quality.

N-50 working with fountain solution (solution B) obtained on the market
The plate begins to develop color at adjustment point 60. The plate working with the fountain solution of the invention (solution A) has adjustment point 22'!
Does not change color. Return the water adjustment to the starting point and repeat the test several times. The working of the plate with the commercially available fountain solution (solution B) cannot be recovered after the third coloring cycle. Working on the plate with the fountain solution of the invention (solution A), the print is still sharp after the 5th color cycle.

Manufacture a new plate and start work at adjustment point 32.

The printing press will be suspended for one hour.

After this interruption, work on the plate begins again.

Plates used with a commercially available fountain solution (solution B) result in dark stains that cannot be removed with increased fountain supply.

The plate must be cleaned with a plate cleaner before obtaining copies of acceptable quality.

The plates used with the fountain solution of the invention (Solution A) work cleanly and produce up to 15 copies of sufficient quality.

It can be readily seen that the fountain solution of the present invention can print sharply at low fountain adjustment points, thereby providing the desired ink/water balance. Moreover, the hydrophilization of the background of the plate during the interruption is sufficient, which results in sufficient and easy working.

Example 3 All tests are repeated in the same manner as in Example 2, except that a second commercially available fountain solution is substituted for that used in Example 2. This fountain solution is particularly suitable for sheet printing presses. This is a small solution of salt, surfactant and alcohol using Acibiame as a substrate. Add 185 g (6.25 oz) of Fountain Solution Concentrate to 18.925 g/(5 gallons) of Improper Tool and water mixture. In this case, use isopropano! Present in an amount of 42Ovolff14. Lower the adjustment point until coloration occurs. This commercially available fountain solution develops color at 30, but the fountain solution of the present invention does not develop color at 22.

In the same way, the interruption was found to be the same as described in Example 2.

Example 4 Using the same method as Example 2, set the rating to NN'-250 plays) to N.
The procedure is carried out except that -50 plates are used instead. N-250
The plate is an electrochemically roughened and anodized negative working plate (Enco Printing Product).
s), a division of the American Hoechst Company.

In this case, the plate using the commercially available fountain solution shows coloration at the adjustment point 28, but the plate using the fountain solution of the present invention shows coloration at the adjustment point 18.

It turns out that the characteristics of the interruption are the same as those described in Example 2.

Example 5 This example shows printing results obtained using a fountain solution prepared according to Example 1 except that propylene glycol was omitted.

A fountain concentrate is prepared as in Example 1 except that the zolopyrene glycol is omitted. All other ingredients and their proportions are the same. The concentrate is diluted as in Example 2 and placed in the first sump of the printing press (solution C). Place the commercially available fountain solution used in Example 2 in another reservoir (
Solution B).

N-50 working with fountain solution (solution B) obtained on the market
The plate begins to develop color at adjustment point 30. Fountain solution containing no propylene glycol (solution C) has adjustment point 2
Color develops at 8. Return the water adjustment to the starting point and repeat the test several times.

Working of the plate with each fountain solution cannot be recovered after the third coloring cycle.

A new plate is manufactured and work begins at adjustment point 62. The printing press will be suspended for one hour.

After this interruption time, work on the unprotected and uncleaned plates begins again. Both plates produce dark stains. The plates used with the commercially available fountain solution (solution B) do not have stains that are removed with increased fountain feeding. Plates using solution C are slightly cleaner, but not enough to be acceptable. Both plates must be cleaned with a plate cleaner before obtaining copies of acceptable quality.

EXAMPLE The example in Example shows the printing results obtained using the fountain solution prepared according to Example 1, except that 2-ethyl-1,6-hexanediol was omitted.

A fountain concentrate is prepared as in Example 1 except that 2-ethyl-1,3-hexanediol is omitted. All other ingredients and their proportions are the same. Example 2 of concentrate
Dilute as follows and place in one reservoir of the printing press (solution D).

The commercially available fountain solution used in Example 2 is placed in the other reservoir (solution B).

Working the N-50 plate with a commercially available fountain solution (Solution B) begins to develop color at adjustment point 30. 2-ethyl-
Fountain solution without 1,6-hexanediol (solution D
) develops color at adjustment points 26-28. Return the water adjustment to the starting point and repeat the test several times). The working of the plates with commercially available fountain solutions cannot be restored after the third coloring cycle. Working of the plate in solution also cannot be recovered after the fourth color development cycle.

Manufacture a new plate and start work at adjustment point 32.

The printing press will be suspended for one hour.

After this interruption time, work begins again with the unprotected and uncleaned plates. Both plates produce dark stains. Plates using commercially available fountain solution (solution B) do not have stains that are removed with increased fountain solution supply.

The plate using the solution is slightly cleaner, but not enough to be acceptable. Both plates must be cleaned with a plate cleaner before obtaining copies of acceptable quality.

Claims (1)

[Claims] 1. Mainly: (a) a hydrophilic rubber forming a water-soluble film of about 2 to 28%;
(b) about 5-25% by weight of a water-soluble or water-mixable glycol having 2 to 6 carbon atoms; (c) 2-ethyl-1
, about 0.5 to 15% by weight of 3-hexanediol; (d) a pH/buffer adjustment of about 0.0, consisting of a mixture of a water-soluble organic acid and a water-soluble alkali metal salt of an organic acid or phosphoric acid;
(e) about 5-32% by weight of a water-soluble metal nitrate; and (f) about 35-65% by weight of water. 2. Approximately 12-18% by weight of glycol and 2-ethyl-1
3-hexanediol. 3-hexanediol. 3. The solution according to claim 2, wherein the glycol is propylene glycol. 4. The solution of claim 1, wherein the gum is gum arabic present in a concentration of about 8-15% by weight. 5. The metal nitrate is selected from the group consisting of magnesium nitrate and zinc nitrate and is present in a concentration of about 10-18% by weight;
A solution according to claim 1. 6. The solution according to claim 1, wherein the organic acid is selected from the group consisting of citric acid, ascorbic acid, sulfanilic acid, tartaric acid, lactic acid and acetic acid, and the salt is an alkali metal salt of one of these acids. . 7. The organic acid is present at a concentration of about 0.75-3.5% by weight;
7. The solution of claim 6, wherein the salt is present in a concentration of about 0.075-0.75% by weight. 8. The solution according to claim 7, wherein the organic acid is glacial acetic acid and the organic acid salt is sodium acetate. 9 further containing about 0.02 to 2.75% by weight of phosphoric acid;
A solution according to claim 1. 10. The solution of claim 9 further comprising an effective amount of a disinfectant. 11, (a) about 8-15% by weight of gum arabic, (b) about 12-18% by weight of propylene glycol, (c) about 2.5% by weight of 2-ethyl-1,3-hexanediol
~7.5% by weight, (d) about 0.75-6.5% by weight of glacial acetic acid, (e) about 0.075-0.
75% by weight, (f) about 10-18% by weight of magnesium nitrate-6H_2O, (g) about 0.25-0.75% by weight of phosphoric acid (85%), and (h) water; A concentrated lithographic fountain solution in which the amount of non-aqueous components is within the range of about 35-65% by weight. 12. Further, the concentrate according to claim 1 is diluted with water, and the amount of non-aqueous components in the diluted solution is about 0.1 to 0.9.
Fountain solution within % by weight. 13. Further, the concentrate according to claim 11 is diluted with water, and the amount of non-aqueous components in the diluted solution is about 0.1 to 0.
Fountain solution in the range of 9% by weight.