JPH0446760B2 - - Google Patents

Abstract

An improved fountain solution suitable for use in a lithographic offset printing press contains a mixture of a polyol and/or glycol ether partially soluble in water and a polyol and/or glycol ether completely soluble in water.

Description

[Detailed description of the invention]

The present invention provides an improved fountain solution suitable for use in lithographic offset printing machines.
Regarding this, the dampening solution contains a mixture of partially water-soluble polyols and/or glycol ethers and completely water-soluble polyols and/or glycol ethers. The lithographic printing process uses dampening water to perform the correct printing operation and obtain high quality prints.
solution or fountain solution). Fountain solutions generally contain water, acids, salts, solvents, and naturally occurring polymeric substances such as gum arabic and/or
or a blend or mixture of various synthetic polymers. The purpose of the dampening solution is to dampen the non-image areas of the printing plate and prevent ink from adhering to these non-image areas. If ink adheres to non-image areas, poor quality prints will be obtained. Traditionally, alcohols, especially isopropanol, at concentration levels of up to 30% by volume have been used in the dampening solution to obtain the best performance in press operation and to obtain high quality prints. The rationale for using isopropyl alcohol lies in part in its ability to transport dampening water to the printing plate by the inked rollers in the printing press or by its own row of rollers. Because of this property, the surface tension of an aqueous solution containing isopropyl alcohol was reduced.
This also causes the dampening solution to become wet and mix with the ink in the Dahlgren system,
Alternatively, the ink and fountain solution may be kept separate while in a lithographic printing press using conventional dispersion methods. However, when the dampening solution is transported in the form of a thin film by rollers, volatile components, especially alcohol, are lost. Besides cost considerations in the loss of alcohol by evaporation, safety considerations for the use of the solution are emphasized. Therefore, it would be desirable to find a substitute for volatile alcohols that does not have the problems associated with the use of isopropyl alcohol. U.S. Pat. No. 3,877,372 describes an attempt to eliminate isopropanol from dampening solutions and to use a mixture of butyl cellosolve, silicone glycol copolymer and defoamer. Some commercial dampening solutions use 2-ethyl-1,3-hexanediol in place of isopropyl alcohol to provide a dampening solution that does not contain isopropyl alcohol. 2-ethyl-1,3
- The use of hexanediol eliminates the toxicity and flammability associated with fountain solutions containing isopropyl alcohol. Fountain solutions containing 2-ethyl-1,3-hexanediol also provide high quality prints in lithographic presses. However, when using fountain solutions containing 2-ethyl-1,3-hexanediol, the appearance of tinting and/or banding in prints is often observed. Chinching is the deposition of fine ink droplets in non-image areas, giving a pale appearance. Bunging is the appearance of interdigitated dark stripes in printed matter. Accordingly, there is a need to develop a non-isopropyl alcohol-containing dampening solution, the use of which eliminates chinching and/or bunging in printed matter. The present inventors have now demonstrated that when a mixture of partially water-soluble polyols and/or glycol ethers and completely water-soluble polyols and/or glycol ethers is used in the dampening solution, chinching in the resulting printed matter is observed. It has been discovered that and/or bunting is substantially reduced and in many cases eliminated. The use of such mixtures in place of isopropyl alcohol eliminates the toxicity and flammability of conventional isopropyl alcohol-containing fountain solutions, yet has other desirable properties that give high quality prints on lithography. You can get dampening water. The dampening solution contains between about 0.5% and about 10% by volume.
containing the mixture. Polyols and/or suitable for use in the present invention
or the mixture of glycol ethers is 2 _- ethyl-1,3-hexanediol, ester diol-204 i.e. _HOCH2C ( _CH3 ) _2CH2OCOC
( _CH3 ) _2CH2OH , hexyl _cellosolve or _C6
Included are partially water-soluble polyols and/or glycols such as H ₁₃ OCH ₂ CH ₂ OH, hexyl carbitol or C ₆ H ₁₃ O(C ₂ H ₄ O) ₂ H, and the like. Polyols and/or glycol ethers which are completely water-soluble are, for example, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, hexylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, 1,
5 _- pentanediol, _methyl cellosolve _{or CH3OC2H4OH} , cellosolve solvent or _C2H5
OC2H4OH , butyl _cellosolve solvent i.e. _C4
Includes H ₉ OC ₂ H ₄ OH, etc. Solubility is determined by determining the weight percent of the polyol and/or glycol ether that is soluble in water at 20°C. A polyol and/or glycol is characterized as partially water soluble if its solubility in water at 20°C is about 0.99 to about 28.0% by weight. For every part by volume of completely water-soluble polyol and/or glycol ether, from about 0.08 to about 10 parts by volume of partially water-soluble polyol and/or glycol ether are used. The fountain solution generally contains several other ingredients.
These components include water-soluble polymers, especially water-soluble rubbers having carboxyl groups and hydroxyl groups. Gum arabic is the oldest and most widely used polymer. Carboxymethylcellulose, hydroxyethylcellulose, as well as styrene-maleic anhydride copolymers, polyvinylpyrrolidone, and the like can also be used. These polymers are generally used in concentrations of about 1 to about 10% by weight. The dampening solution is preferably used as an acidic aqueous solution. Phosphoric acid is the preferred acid for use in acidifying the formulation. Other acids that can be used include inorganic acids such as acetic acid, nitric acid, hydrochloric acid, and the like, as well as organic acids. Buffers such as ammonium acetate can also be included. The dampening solution is generally maintained at a pH of about 2 to about 5.
However, each individual where a given dampening solution is kept
PH is related to factors such as the type of water-soluble polymer used, other ingredients in the fountain solution, and the type of substrate used in the lithographic printing plate. Other additives that can be used in the dampening solution include preservatives such as phenol, sodium salicylate, ammonium dichromate,
Corrosion inhibitors such as magnesium nitrate, zinc nitrate etc.; hardeners such as chromium, aluminum etc.; organic solvents such as cyclic ethers, e.g. 4-butyrolactone etc.; low molecular weight aldehydes such as formaldehyde, glutaraldehyde etc. include. These additives are generally used in amounts of about 0.1 to about 10% by volume. The following examples illustrate specific embodiments of the invention, but the invention is not limited thereto. Control Example The following ingredients were mixed together to form a fountain solution base: Approximately 14 g (0.5 oz) of gum arabic, phosphoric acid (5% aqueous solution)
Approximately 14g (0.5oz), and water approximately 3600g (127.0oz). Approximately 37 grams of 2-ethyl-1,3-hexanediol in a formulation equal to approximately 3.8 (1 gallon) of the above
(1.3 oz.) was added to prepare a 1% concentration by volume of 2-ethyl-1,3-hexanediol. The dampening solution was used in a 25 inch production size printing press using the Dahlgren recirculating dampening solution system. While printing approximately 200 sheets of paper for each set,
The press was operated with dampening rollers set at speeds of 40, 50 and 60. The optical density of the prints was measured for each set. These optical densities were measured using an optical densitometer. Also scum (scum,
A circulation test was conducted for soiling. In this test, the dampening water supply was momentarily stopped to ensure that the printing plate was completely coated with ink. Next, supply of dampening water was started, and the number of rotations of the printing plate before cleaning the excess ink from the printing plate was recorded. Furthermore, the printed matter was visually observed to measure the appearance of chinching and bunging. The results are shown in the table. Example 1 The following ingredients were mixed together to form a dampening solution: Gum Arabic approximately 14 g (0.5 oz), Phosphoric Acid (5% aqueous solution) approximately 14 g (0.5 oz), Water approximately 3600 g (127.0 oz). , 2-ethyl-1,3-hexanediol
Approximately 37 g (1.3 oz), and propylene glycol
Approximately 193g (6.8oz). According to the above formulation, 2-ethyl-
1,3-hexanediol and propylene glycol at a concentration of 5% by volume were obtained. The dampening solution described above was tested as described in Control Example A above. The results are shown in the table. Example 2 The following ingredients were mixed together to form a dampening solution: approximately 14 g (0.5 oz) of gum arabic, approximately 14 g (0.5 oz) of phosphoric acid (5% aqueous solution), and approximately 3600 g (127.0 oz) of water. , 2-ethyl-1,3-hexanediol
Approximately 37 g (1.3 oz), and dipropylene glycol
Approximately 193g (6.8oz). The dampening solution described above was tested as described in Control Example A above. The results are shown in the table. Example 3 The following ingredients were mixed together to form a dampening solution: approximately 14 g (0.5 oz) of gum arabic, approximately 14 g (0.5 oz) of phosphoric acid (5% aqueous solution), and approximately 3600 g (127.0 oz) of water. , 2-ethyl-1,3-hexanediol
Approximately 37 g (1.3 oz), and diethylene glycol
Approximately 193g (6.8oz). The dampening solution described above was tested as described in Control Example A above. The results are shown in the table. Example 4 The following ingredients were mixed together to form a dampening solution: approximately 14 g (0.5 oz) of gum arabic, approximately 14 g (0.5 oz) of phosphoric acid (5% aqueous solution), and approximately 3600 g (127.0 oz) of water. , 2-ethyl-1,3-hexanediol
Approximately 37g (1.3oz) and hexylene glycol
Approximately 193g (6.8oz). The dampening solution described above was tested as described in Control Example A above. The results are shown in the table.

[Table] Severe bunge
ng
The data in the table is generally 2-ethyl-1,3
- shows that higher optical density values are obtained when hexanediol is mixed with glycol.
Also, when 2-ethyl-1,3-hexanediol is mixed with glycol, the scum circulation values are generally lower, meaning that the addition of glycol improves the cleaning performance. Additionally, the addition of glycol to 2-ethyl-1,3-hexanediol tends to reduce tinging and bunting. Examples 5-9 In these examples, 2-ethyl-1,
Fountain solutions were prepared using 3-hexanediol and propylene glycol, where the concentration of propylene glycol was varied. Example 5 The following ingredients were mixed together to form a dampening solution: approximately 14 g (0.5 oz) of gum arabic, approximately 14 g (0.5 oz) of phosphoric acid (5% aqueous solution), and approximately 3600 g (127.0 oz) of water. , 2-ethyl-1,3-hexanediol
Approximately 37g (approximately 1.3 oz), and propylene glycol
Approximately 74g (approximately 2.6 ounces). The above formulation yielded propylene glycol at a concentration of 2% by volume. The above formulation was used in the printing machine described in Control Example A above. The following different inks were used: Offset Ink No. 205; Heatset Web Offset Ink No. 204; and an acrylic modified sheet offset ink similar to No. 205 (National
Association Printing Ink Manufacturers,
August 1974). Optical density was measured. A scum circulation test was also conducted. The results are shown in the table. Example 6 Example 5 above was repeated exactly, except that about 147 grams (5.2 ounces) of propylene glycol was used. This formulation yielded a 4% concentration of glycol by volume. The results are shown in the table. Example 7 Example 5 above was repeated exactly, except that approximately 7.8 ounces of propylene glycol was used. The formulation yielded a glycol concentration of 6% by volume. The results are shown in the table. Example 8 Propylene glycol approximately 297 g (10.4 oz)
Example 5 above was exactly repeated except that . The formulation yielded a glycol concentration of 8% by volume. The results are shown in the table. Example 9 Propylene glycol approximately 369 g (13.0 oz)
Example 5 above was exactly repeated except that . The formulation yielded a glycol concentration of 10% by volume. The results are shown in the table.

【table】

Claims (1)

[Claims] 1. Partially water-soluble polyols and/or glycol ethers with a solubility between 0.99% and 28% by weight in water at 20°C and completely water-soluble polyols and/or glycols. An improved fountain solution suitable for use in lithographic offset printing machines, characterized in that it contains between 0.5% and 10% by volume of a mixture with ether. 2 Partially water-soluble glycol is 2-ethyl-
A dampening solution according to claim 1, comprising 1,3-hexanediol. 3 Glycols that are completely water-soluble are from one or more of propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, hexylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol and 1,5-pentanediol. Selected claim 1 or 2
Dampening water as described in section.