JP7106240B1 - Neutral dampening solution composition and concentrated dampening solution composition for offset printing - Google Patents

Abstract

A neutral dampening water composition for offset printing is provided, which is less likely to cause rusting of iron members used in printing presses and which can reduce wasted paper when printing plates of on-press development method are used. provide. Kind Code: A1 Addition of at least one salt selected from the group consisting of respective salts of suberic acid, azelaic acid, undecanedioic acid and dodecanedioic acid to a dampening water composition provides rust prevention and on-press developability. and can improve both. Specifically, a neutral dampening water composition for offset printing having a pH of more than 5 and less than 9, wherein each of suberic acid, azelaic acid, undecanedioic acid and dodecanedioic acid is added to the total amount of the composition. A neutral fountain solution composition for offset printing characterized by containing 0.0001 to 0.04% by mass of at least one salt selected from the group consisting of salts of . [Selection figure] None

Description

The present invention relates to neutral and concentrated dampening water compositions for offset printing.

Offset printing is a printing method that utilizes the water-repellent property of an oil-based ink composition for offset printing (hereinafter, abbreviated as "ink composition" or "ink" as appropriate). Unlike the letterpress printing method that uses a plate, it is characterized by using a printing plate without unevenness. This printing plate has oleophilic image areas and hydrophilic non-image areas instead of unevenness. During printing, first, the non-image areas of the printing plate are moistened with dampening water to form a water film on the surface, and then the ink composition is supplied to the printing plate. At this time, the supplied ink composition does not repel and adhere to the non-image areas where the water film is formed, but adheres only to the lipophilic image areas. Thus, printing is effected by forming an image with the ink composition on the surface of the printing plate, which is then sequentially transferred to the blanket and paper.

The simplest form of dampening water used at this time may be water alone, but water alone often fails to sufficiently satisfy the functions required of dampening water. For example, if the amount of dampening water supplied is not appropriate, the ink composition may not be sufficiently transferred to the image area, resulting in a decrease in image density, or the ink composition may adhere to the non-image area, resulting in printing stains. However, if the composition of the dampening solution is only water, the range of the appropriate supply amount is narrow (this is the so-called "narrow water width" state), and even a slight change in the printing conditions will Hard to get prints. Therefore, usually, various additives such as acids, bases and their salts, surfactants, and wettable water-soluble resins are added to improve the viscosity, surface tension, pH, and emulsifying properties of the ink composition. It is common to adjust the amount of dampening water to increase the proper amount of dampening water supplied.

For this reason, if the dampening water composition contains an acid or a base, it is usually in the acidic or alkaline range (see, for example, Patent Documents 1 and 2). It cannot meet the effluent standards (for example, according to the Sewerage Act, the pH is more than 5 and less than 9), and neutralization treatment is required at the time of effluent. However, since the neutralization process requires extra labor and cost, recently, neutral dampening water that does not require this process and meets the wastewater standards has been proposed (see, for example, Patent Document 3).

On the other hand, in the field of preparing printing plates for offset printing, conventionally, a lithographic printing plate precursor (PS plate) comprising a hydrophilic support and a lipophilic photosensitive resin layer provided thereon is used. After exposing through a film-like mask containing information such as characters and images, development processing is performed using an alkaline developer or the like to leave a photosensitive resin layer corresponding to the image area, while corresponding to the non-image area. The printing plate was obtained by dissolving and removing the unnecessary photosensitive resin layer. With the subsequent progress of digitization, a direct exposure method that draws information such as characters and images with laser light using CTP (Computer to Plate) technology without using a film mask is generally performed. Recently, an on-machine development system, which does not require development with a developer, is also being adopted.

In the on-press development method, after the lithographic printing plate precursor is exposed, development is performed by mounting the plate as it is on a printing press and starting printing without performing development. In this method, in the initial stage of printing, the photosensitive resin layer in the non-image area swells with dampening water and is easily peeled off, which is taken into the ink composition and removed from the printing plate precursor. to complete the development. The plate-making method of the on-press development method not only has the advantage of simplifying the process by eliminating the development process, but also has the advantage of being environmentally friendly as it can be developed without using an alkaline developer. Various types of original printing plates for on-press development have been proposed to enable such development (see, for example, Patent Document 4).

JP-A-05-318958 JP-A-06-127170 JP-A-2005-28853 JP 2012-66577 A

By the way, in recent years, there is a tendency for rotary presses used for offset printing to be faster, lighter, and smaller. A rotary press for printing newspapers can be cited as a rotary press for offset printing, which is particularly fast. Offset printing presses are equipped with a dampening water supply mechanism for realizing uniform supply of dampening water to the printing plate in order to obtain good printed matter. As such, a spray dampening method is often adopted. The spray dampening system is a system in which a mist of dampening water is sprayed from nozzles and supplied to the printing plate. The droplets of dampening water sprayed from the nozzle become smaller and faster, and a large amount of dampening water stays in the narrow space inside the printing machine and drifts, and adheres to various metal parts of the printing machine. As a result, it causes iron rust.

In addition, as mentioned above, the number of cases in which on-press development printing plates are being used has been increasing in recent years. , there is a tendency to increase the amount of wasted paper until the printed matter as a product is obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to prevent iron members used in printing presses from rusting and to reduce wasted paper when printing plates of the on-press development system are used. An object of the present invention is to provide a neutral dampening water composition for offset printing.

As a result of extensive studies to solve the above problems, the present inventors have found that a neutral dampening solution composition for offset printing having a pH of more than 5 and less than 9 contains a salt of a specific aliphatic dibasic acid. By containing 0.0001 to 0.04% by mass with respect to the total amount of the composition, it was found that iron rust can be suppressed and waste paper can be reduced when using a printing plate of the on-press development method. The present invention has been completed. Specifically, the present invention provides the following.

(1) The present invention provides a neutral dampening solution composition for offset printing having a pH of more than 5 and less than 9, wherein suberic acid, azelaic acid, undecanedioic acid and dodecanedioic acid are added to the total amount of the composition. contains 0.0001 to 0.04% by mass of at least one salt selected from the group consisting of each of the salts of and when dodecanedioic acid is selected, the salt is sodium salt, potassium salt or ammonium salt A neutral dampening water composition for offset printing characterized by:

(2) The present invention also provides a neutral fountain solution composition for offset printing according to item (1), wherein the salt is sodium salt, potassium salt or ammonium salt.

(3) The present invention also provides a neutral fountain solution composition for offset printing according to (1) or (2), which further contains an inorganic acid salt and/or an organic acid salt.

(4) The present invention also includes a salt of a phosphoric acid compound as at least part of the inorganic acid salt, and the content concentration in the composition is 32 mg/L or less in terms of pure phosphorus content (3). A neutral dampening solution composition for offset printing as described.

(5) The present invention also provides a neutral fountain solution composition for offset printing according to item (4), wherein the salt of the phosphoric acid compound is a salt of hexametaphosphoric acid.

(6) The present invention also provides a neutral fountain solution composition for offset printing according to any one of items (1) to (5), further comprising a preservative.

(7) The present invention also provides a neutral fountain solution composition for offset printing according to item (6) , wherein the preservative is a thiazoline compound.

(8) The present invention also provides a concentrated dampening solution composition for preparing a neutral dampening solution composition for offset printing according to any one of items (1) to (7).

INDUSTRIAL APPLICABILITY According to the present invention, a neutral dampening solution for offset printing can prevent iron members used in a printing press from rusting and can reduce paper waste when using an on-press developing printing plate. A composition is provided.

Hereinafter, one embodiment of the neutral dampening water composition for offset printing of the present invention (hereinafter abbreviated as the dampening water composition of the present invention, etc.) and one embodiment of the concentrated dampening water composition. explain. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

The dampening water composition of the present invention is preferably used as dampening water for offset printing, and has a neutral pH of more than 5 and less than 9. Therefore, the dampening water composition of the present invention conforms to the pH standard for wastewater stipulated by law (the Sewerage Act), and can be treated as wastewater without special neutralization treatment. In some cases, the pH range of 5 to 6 is treated as weakly acidic, and the pH range of 8 to 9 is treated as weakly alkaline. treated as

The dampening water composition of the present invention can be applied to offset printing in general using dampening water. Examples of such offset printing include commercial printing for printing posters, packages, books, etc., and newspaper printing for printing newspapers. Also, the printing method is not particularly limited and includes sheet-fed printing, rotary printing, and the like. As already mentioned, the dampening solution composition of the present invention is excellent in rust prevention and on-press developability of printing plates. It is preferably applied to newspaper printing, where on-press development of printing plates with dampening water is actively practiced.

The dampening water composition of the present invention is a neutral dampening water composition for offset printing having a pH of more than 5 and less than 9, wherein suberic acid, azelaic acid, undecanedioic acid and suberic acid are added to the total amount of the composition. characterized by containing 0.0001 to 0.04% by mass of at least one salt selected from the group consisting of respective salts of dodecanedioic acid, preferably inorganic acid salts and/or Including organic acid salts. Each component will be described below.

At least one salt selected from the group consisting of salts of suberic acid, azelaic acid, undecanedioic acid and dodecanedioic acid imparts anticorrosive properties to the dampening solution composition of the present invention and on-press development of printing plates. contribute to endowment. Since these salts are salts of aliphatic dibasic acids, these salts are hereinafter also referred to as "salts of aliphatic dibasic acids". In fields other than dampening water compositions, there are examples of using such salts of aliphatic dibasic acids as anticorrosion components. It can be said that it is an unexpected finding that on-press developability is improved in addition to rust resistance. As already stated, the present invention was made based on such findings. Undecanedioic acid is also called 1,9-nonanedicarboxylic acid, and dodecanedioic acid is also called 1,10-decanedicarboxylic acid. Suberic acid, azelaic acid, undecanedioic acid, and dodecanedioic acid are all commercially available as raw materials for nylon and pharmaceuticals, and can be easily obtained.

As cations constituting salts of aliphatic dibasic acids, sodium ions, potassium ions, ammonium ions and the like are preferably exemplified. In this case, the salt of the aliphatic dibasic acid is sodium salt, potassium salt or ammonium salt. In addition, although the aliphatic dibasic acid has two carboxy groups, both of these carboxy groups may form a salt with the same cation, or only one of them may form a salt and the other one of the carboxy groups may form a salt. It may remain as it is, or the two carboxy groups may form salts with different cations (eg, sodium ion and ammonium ion).

The amount of the aliphatic dibasic acid salt added to the dampening water composition of the present invention is 0.0001 to 0.04% by mass based on the entire dampening water composition of the present invention. The amount to be added is preferably 0.0025 to 0.04% by mass based on the entire dampening water composition of the present invention, and 0.01 to 0.04% by mass based on the entire dampening water composition of the present invention. 04% by mass is more preferred. When the amount of the aliphatic dibasic acid salt added to the dampening water composition is within the above range, both rust prevention and on-press developability of the printing plate can be satisfactorily achieved.

An inorganic acid salt and/or an organic acid salt can be added to the dampening water composition of the present invention. These salts are ingredients that function as surface conditioners.

Preferred examples of inorganic acid salts include nitrates, salts of phosphoric acid compounds, borates, sulfates, and aluminum alum. Preferred examples of these salts include sodium salts, potassium salts, ammonium salts and the like. Examples of nitrates include sodium nitrate, potassium nitrate, ammonium nitrate, magnesium nitrate and the like. In the dampening water composition of the present invention, the amount of the inorganic acid salt added, excluding the salt of the phosphoric acid compound, is 0.0015 to 0.03% by mass based on the entire dampening water composition of the present invention. It is preferably mentioned, and more preferably 0.0025 to 0.02% by mass. By setting the amount to be added within the above range, not only can good printability be obtained, but also good stability can be obtained when the concentrated dampening water composition is formed. These inorganic acid salts may be used singly or in combination.

Salts of phosphoric acid compounds include sodium salts and potassium salts of phosphoric acid, hexametaphosphoric acid, orthophosphoric acid, polyphosphoric acid, tripolyphosphoric acid, and the like. Among these, hexametaphosphate is preferred, and sodium hexametaphosphate is more preferred.

Here, since the Sewerage Act stipulates that the phosphorus content in wastewater is less than 32 mg/L, the concentration of the salt of the phosphoric acid compound added to the dampening water composition is converted to pure phosphorus. It is preferred to add the salt of the phosphate compound so that the . Here, the "concentration when the salt of the phosphate compound is converted to pure phosphorus" is the concentration of phosphorus atoms contained in the salt of the phosphate compound represented by the following formula.
Concentration of phosphorus atoms = C _comp. × Pn _comp. × Atomic weight of phosphorus/Mw _comp.
C _comp .: Concentration of the salt of the phosphate compound in the dampening water composition Pn _comp .: Number of phosphorus atoms contained in one molecule of the salt of the phosphate compound Mw _comp .: Molecular weight of the salt of the phosphate compound

In addition, when a plurality of types of salts of the phosphate compound are contained, it is the sum of the concentrations converted to pure phosphorus in each of the salts of the phosphate compound. For example, when 1 L of dampening water composition contains 10 mg of monosodium phosphate (molecular weight: 119.98) and 10 mg of trisodium phosphate (molecular weight: 163.92), the pure phosphorus content of the salt of the phosphate compound is The converted concentration is (10×30.97/119.98)+(10×30.97/163.92)=4.47 mg/L.

When the dampening water composition of the present invention contains a salt of the phosphoric acid compound, the preferred upper limit of the concentration in terms of pure phosphorus is 16 mg/L, which satisfies the standard value of the Water Pollution Control Law and the Tokyo Sewerage Ordinance. and a more preferable upper limit is 8 mg/L, which satisfies the daily average of the Water Pollution Control Law.

As the organic acid salt, those different from the salts of the aliphatic dibasic acids described above are used, and sodium salts, potassium salts, ammonium salts of succinic acid, citric acid, tartaric acid, malic acid and the like are preferably mentioned. can. Among these, malate and citrate are preferred, and sodium malate and trisodium citrate are more preferred. The amount of organic acid salt to be added is preferably 0.0025 to 0.05% by mass, more preferably 0.01 to 0.03% by mass, based on the entire dampening water composition of the present invention. 0.01 to 0.02% by mass is more preferable. When the amount added is within the above range, not only can good printability be obtained, but also good stability can be obtained when the concentrated dampening water composition is formed. Incidentally, these organic acid salts may be used alone, or may be used in combination.

The fountain solution composition of the present invention preferably contains a preservative. Since the dampening water composition of the present invention contains a preservative, it suppresses putrefaction due to bacteria in the dampening water supply device containing the dampening water and the growth of microorganisms such as mold and yeast, thereby improving printability due to them. deterioration can be suppressed.

Examples of antiseptics include organic nitrogen sulfur compounds, organic nitrogen compounds, organic bromine compounds, organic copper compounds, benzimidazole compounds, thiazoline compounds, N-halomethylthiophthalimide compounds, and triazine compounds. be able to. Among these, thiazoline-based compounds are preferred as preservatives. The thiazoline-based compound has good stability over time, and the antiseptic effect of the fountain solution composition of the present invention can be obtained over a long period of time.

More specific examples of such thiazoline compounds include 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4- Isothiazolin-3-one and the like can be mentioned.

The amount of antiseptic added is preferably 0.0001 to 0.05% by mass based on the entire dampening water composition of the present invention. Preservatives may be used singly or in combination.

Examples of water constituting the dampening water composition of the present invention include pure water (ion-exchanged water, RO water), soft water (cation-exchanged water), tap water, well water, and the like.

The dampening water composition of the present invention may optionally contain components such as a water-soluble resin, a wetting agent, a surfactant, an antifoaming agent, and a rust preventive agent other than the salt of the aliphatic dibasic acid. It may be added as appropriate.

Examples of the water-soluble resin include, without particular limitation, those that have hitherto been used in dampening water compositions. Examples of such water-soluble resins include gum arabic, carboxymethyl cellulose, methyl glucoside, pectin, polyvinylpyridone, polyvinyl alcohol, methyl vinyl ether, maleic anhydride copolymer, and alginic acid. These water-soluble resins may be used alone or in combination.

Examples of the wetting agent include, without particular limitation, those that have hitherto been used in dampening water compositions. Examples of such humectants include alcohols, glycols, glycerins, and the like. These wetting agents may be used alone or in combination.

Surfactants that have hitherto been used in dampening water compositions can be used without particular limitation. Examples of such water-soluble resins include glycerin fatty acid ester-based, polyglycerin fatty acid ester-based, propylene glycol fatty acid ester-based, pentaerythritol fatty acid ester-based, polyoxyethylene-based (polyoxyethylene alkylphenyl ethers, polyoxyethylene poly styryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene-polyoxypropylene block polymers, etc.). These surfactants may be used alone or in combination.

Antifoaming agents that have hitherto been used in dampening water compositions can be used without particular limitation. Examples of such antifoaming agents include silicon-based antifoaming agents. These antifoaming agents may be used alone or in combination.

Examples of the antirust agent other than the salt of the aliphatic dibasic acid include, without particular limitation, those that have hitherto been used in dampening water compositions. Examples of such antirust agents include tetrazole compounds and/or water-soluble salts thereof, benzotriazole compounds, and the like. Specific examples of tetrazole compounds and/or water-soluble salts thereof include 5-substituted-1H-tetrazoles, 1-substituted-1H-tetrazoles, 1-substituted-5-substituted-1H-tetrazoles, and water-soluble salts thereof. , 1H-tetrazole, 5-amino-1H-tetrazole, and water-soluble salts thereof (especially salts of organic nitrogen-containing compounds). These rust inhibitors may be used alone or in combination.

To prepare the dampening water composition of the present invention, the salt of the above aliphatic dibasic acid is added to water such as pure water (ion-exchanged water, desalted water) or soft water. The ingredients may be added and stirred and mixed with a stirrer. Alternatively, the dampening water composition of the present invention may be prepared by preparing a concentrated dampening water composition and diluting it with water such as pure water, soft water, or tap water at the printing site at the time of use. In this case, the concentration ratio of the dampening water composition can be about 100 to 300 times.

According to the dampening solution composition of the present invention, excellent on-press developability of the printing plate can be obtained in addition to excellent rust prevention for iron members of the printing press. Further, according to the dampening water composition of the present invention, thickening of the emulsified ink during printing is suppressed, and surface smoothness after on-press development is also excellent, so excellent printability can be obtained. Further, the dampening water composition of the present invention has high dissolution stability and hardly separates and precipitates. Therefore, it can be stably stored for a long period of time even if it is concentrated 100 times or more for market distribution.

A concentrated dampening water composition for preparing the dampening water composition of the present invention is also one aspect of the present invention. As described above, the dampening water composition of the present invention is excellent in stability when concentrated, so it can be treated as a concentrated dampening water composition of 50 times or more, as well as 100 times or more. This concentrated dampening water composition is diluted, for example, 50 to 300 times when used at a printing site, and used as the dampening water composition of the present invention.

EXAMPLES Hereinafter, the dampening water composition of the present invention will be described in more detail by showing examples, but the present invention is not limited to the following examples.

[Dampening water compositions of Examples 1 to 24 and Comparative Examples 1 to 10]
Dampening solution compositions of Examples 1 to 24 and Comparative Examples 1 to 10 were prepared by mixing the materials shown in Tables 1 to 5 with a stirrer. In Tables 1 to 5, "surface conditioning agent 1" is sodium malate, "surface conditioning agent 2" is trisodium citrate, and "surface conditioning agent 3" is sodium nitrate. "Surface conditioner 4" is sodium orthophosphate, "Surface conditioner 5" is sodium pyrophosphate, "Surface conditioner 6" is sodium tripolyphosphate, "Surface conditioner 7" is It is sodium hexametaphosphate. In Tables 1 to 5, "preservative" is methylisothiazolinone, "surfactant" is polyoxyethylene alkyl ether, and "water" is soft water with a total hardness of about 0 mg/L. be. The blending amount of each component shown in Tables 1 to 5 is all % by mass.

For each of the dampening water compositions of Examples 1 to 24 and Comparative Examples 1 to 10, rust prevention, on-press developability, emulsification thickening of the ink composition, and surface smoothness after development were evaluated according to the following procedures. , and stability of the concentrated fountain solution composition.

[Rust prevention evaluation]
60 mL of the dampening water composition was placed in a 100 mL plastic container, an iron plate (iron piece) for testing was placed therein, and the container was sealed and left at room temperature. The steel piece was sized such that about two-thirds of the piece was immersed in the dampening solution composition and about one-third of the top was exposed to the air. Evaluation was performed using five iron pieces per one dampening solution composition, and the number of hours until rust was observed on two of the five iron pieces was taken as an evaluation point. For example, if rust is observed on two iron pieces after 3 hours, the score is 3 points, and if rust is observed on 2 iron pieces after 3 days, 3 days x 24 hours = Since it is 72, the evaluation point is 72 points. Since the test period was 30 days, the maximum evaluation score was 30 days×24 hours=720 points. The results obtained from this test are described in the column of "rust prevention evaluation points" in Tables 1-5.

[On-press developability evaluation]
The exposed, undeveloped on-press development type printing plate is mounted on the printing press (newspaper rotary press manufactured by Tohama Seiki Co., Ltd.), and the rotary press is started with the dampening roller and blanket roller in contact with the printing plate. It was rotated for printing 500 copies without supplying ink. A spray dampener (SSD-12, manufactured by Sakata Inx Co., Ltd.) was used to supply dampening water during rotation, and the spray values of the three nozzles were set to 20, 20, and 20, respectively. After the rotary press was rotated for printing 500 copies, the rotation of the rollers and spraying of dampening water were stopped, the printing plate was removed, and the development state was observed. The development state was evaluated at the central portion of the printing plate, and the ratio (%) of the developed area was calculated. That is, no development results in a rating of 0%, and complete development results in a rating of 100%. The results obtained from this test are shown in the "On-machine developability" column of Tables 1-5.

[Evaluation of emulsifying thickening property of ink composition]
A predetermined amount of ink composition (product name: Luce Y-TS Magenta for newspaper offset printing, manufactured by Sakata Inx Co., Ltd.) is wound on a roller arrangement machine imitating a printing press, and dampening water is applied while the roller is rotating at high speed. The composition was spray fed. The lack of threading in this machine results in excess dampening solution composition and emulsification of the ink composition on each roller. After rotating the machine for a predetermined time, the emulsified ink on the roller was sampled, and the viscosity of the sampled emulsified ink was immediately measured. Evaluation was performed by comparing the viscosity of this emulsified ink with the viscosity of the ink composition before emulsification. If the emulsified ink has a large change in viscosity, problems such as ink sticking to the wet dampening roller may occur in actual printing due to a decrease in transferability of the emulsified ink. The evaluation criteria are as follows, and the evaluation results are shown in the "emulsification thickening property" column of Tables 1 to 5.
○: Viscosity change was small ○～△: Viscosity change that can be used normally without problems △: Viscosity change that can be used but may cause problems ×: Viscosity change that is likely to cause problems in the actual machine was

[Evaluation of surface smoothness after development]
The surface regularity of each dampening water composition was evaluated by printing using a newspaper rotary press manufactured by Higashihama Seiki Co., Ltd. The ink composition used for printing was newspaper offset printing ink (product name: Luce Y-TS Magenta) manufactured by Sakata Inx Co., Ltd. The printing plate used was a completely developed one, and the printing speed was 120,000 copies. / Time. The amount of water that does not cause printing stains with the dampening water composition of Comparative Example 2 is taken as the standard water amount, and for each dampening water composition, the water amount is gradually reduced from this standard water amount, and the paper surface is stained at each step. The extent was relatively evaluated and observed. Using the result of the dampening water composition of Comparative Example 2 as a standard, the evaluation criteria were as follows. In addition, when the evaluation result was positioned between each of the following evaluations of ◎, ○, △, and ×, it was described as ○ to △, for example.
A: Stain on paper was less than when the dampening water composition of Comparative Example 2 was used B: Stain on paper was the same as when the dampening water composition of Comparative Example 2 was used There was more staining on paper than when the dampening water composition was used. ×: There was significantly more staining on paper than when the dampening water composition of Comparative Example 2 was used.

[Evaluation of stability of concentrated dampening water composition]
The dampening water compositions of Examples and Comparative Examples shown in Tables 1 to 5 were added to pure water at 100 times the weight percentage of each component except for water, and dissolved by stirring. This operation results in the preparation of a 100-fold concentrated dampening solution composition for each dampening solution composition. After the stirring was completed, the mixture was filtered, and the filtrate (that is, a dampening water composition concentrated 100 times) was divided into three equal portions, each of which was placed in a transparent container and sealed. The three samples obtained were separately stored at (1) refrigeration at 0 to 2°C for 4 days, (2) heating at 50 to 53°C for 4 days, and (3) room temperature for 1 month, and Deterioration such as precipitation or separation and discoloration was visually observed and evaluated. The evaluation criteria were as follows, and the evaluation results are shown in the "concentration stability" column of Tables 1-5. It should be noted that the 100-fold concentrated dampening water composition is established up to the following Δ evaluation. The dampening solution composition is usually delivered to a printing plant in the form of a concentrated dampening solution composition, and diluted to a predetermined concentration at the printing site for use. Concentrated fountain solution compositions are exposed to winter and summer temperature conditions during distribution and inventory, and this evaluation takes into account such conditions.
○: No change in appearance is observed under any of the three temperature conditions ○ ~ △: Slight discoloration and slight separation are observed, but are resolved by returning to room temperature However, when it is returned to room temperature, it returns to a uniform state. ×: Precipitation, separation, or discoloration is noticeable, and stirring is necessary because this does not disappear just by returning to room temperature.

Further, the dampening water composition of Example 15 and the six types of dampening water compositions on the market (commercial products 1 to 6) were evaluated as described above for rust prevention and on-press developability. did Table 6 shows the results. For each commercially available product, the dampening water composition in a concentrated state was diluted 100 times and used for evaluation.

As shown in Table 6, dampening water compositions with a rust prevention evaluation score of more than 48 exhibit a rust prevention property equal to or higher than that of commercially available products. Also, as shown in Table 6, dampening water compositions exhibiting on-press developability exceeding 80% are commercial products or better. From this point of view, referring to Tables 1 to 5, by containing 0.0025% by mass or more of suberate, azelate, undecanedioate, or dodecanedioate, rust prevention and on-press developability gives better results than the commercial products, and these results become even better with increasing content of these salts. If the on-press developability is improved, waste paper immediately after the start of printing can be reduced when printing is performed using a printing plate of the on-press development method. Incidentally, when the content of these salts reaches 0.05% by mass, it turns out that the results are not favorable in terms of the viscosity increase of the emulsified ink and the stability of the concentrated dampening water (Comparative Examples 3 to 10). ).

When comparing Examples 3, 9 and 15, among suberate (8 carbon atoms), azelate (9 carbon atoms) and undecanedioate (11 carbon atoms), undecanedioate with a large number of carbon atoms The result is the best in terms of rust prevention and on-press developability, and it can be seen that this effect decreases as the number of carbon atoms decreases. As the number of carbon atoms decreases, the performance of rust prevention and on-press development tends to deteriorate rapidly. From the aspect, it is expected to be unfavorable.

In addition, as shown in Examples 21 to 24, dodecanedioate is more effective in emulsifying and thickening the ink and improving the alignment of the developed plate compared to other salts of aliphatic dibasic acids with a lower number of carbon atoms. The appearance tended to be slightly inferior. Also, the dodecanedioate has a higher concentration stability than other salts of aliphatic diacids with lower carbon numbers, which is thought to be due to the lower solubility in dampening water associated with the higher carbon number. decreased. Thus, when the number of carbon atoms in the salt of an aliphatic dibasic acid is increased, up to dodecanedioic acid salts with 12 carbon atoms can be preferably used, but those with a larger carbon number than dodecanedioic acid are not suitable for dampening water. Expected to be unsuitable for use.

Claims (8)

A neutral dampening water composition for offset printing having a pH of more than 5 and less than 9,
0.0001 to 0.04% by mass of at least one salt selected from the group consisting of salts of suberic acid, azelaic acid, undecanedioic acid and dodecanedioic acid relative to the total amount of the composition, and dodecane Neutral fountain solution composition for offset printing, characterized in that when a diacid is selected, said salt is a sodium, potassium or ammonium salt . 2. A neutral fountain solution composition for offset printing according to claim 1, wherein said salt is sodium salt, potassium salt or ammonium salt. 3. The neutral fountain solution composition for offset printing according to claim 1, further comprising an inorganic acid salt and/or an organic acid salt. 4. A neutral dampening solution for offset printing according to claim 3, wherein at least a part of said inorganic acid salt contains a salt of a phosphoric acid compound, and the content concentration in said composition is 32 mg/L or less in terms of pure phosphorus content. water composition. 5. A neutral fountain solution composition for offset printing according to claim 4, wherein the salt of the phosphoric acid compound is a salt of hexametaphosphoric acid. The neutral fountain solution composition for offset printing according to any one of claims 1 to 5, further comprising a preservative. 7. A neutral fountain solution composition for offset printing according to claim 6 , wherein said preservative is a thiazoline compound. A concentrated dampening solution composition for preparing a neutral dampening solution composition for offset printing according to any one of claims 1-7.