JP2010138277A - Detergent for offset printing and cleaning method for offset printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detergent for offset printing exhibiting excellent cleaning performance for ink and paper powders and also having less adverse effect on a printing area in a printing plate and an etching solution by using specific alkylene glycol ether and water at a predetermined ratio as the detergent for offset printing. <P>SOLUTION: In the detergent for offset printing including alkylene glycol ether and water and a cleaning method using the detergent, water solubility of the alkylene glycol ether is set within 3-20 pts.wt. based on 100 pts.wt. of water, and also a blending amount of the alkylene glycol ether is set within 400-2,000 pts.wt. based on 100 pts.wt. of water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cleaning agent for offset printing and a cleaning method for an offset printing apparatus using the same. In particular, the present invention relates to a cleaning agent for offset printing excellent in not only ink in an offset printing apparatus but also paper dust removal property and a cleaning method for an offset printing apparatus using the same.

The cleaning agent for offset printing is not only required to have ink detergency, but also due to the recent decline in paper quality, paper dust is likely to be generated, and the offset printing device has good removability of such paper dust. It is desired.
Here, paper dust that requires cleaning and removal adheres to blankets, impression cylinders, and ink rollers, and particularly deposits on both the left and right sides of the printing direction, often occurring near the cut surface of the paper. It has been confirmed that
In addition, as a constituent of paper dust, it is a mixture of pulp, starch, sizing agent, coating agent, ink, etc. used at the time of papermaking, and it becomes hard when deposited, thereby breaking the balance of nip pressure. Become.
On the other hand, with regard to the print quality, clean skin color is required, or more precise print quality is required, and washing for offset printing that can be printed accurately without damaging the image area on the printing plate. An agent was desired.

Therefore, as one of the cleaning agents for offset printing, the ink and paper powder can be cleaned simultaneously, the drying property is good, the rubber component as a constituent material of the blanket is not swollen, and the workability is low. A cleaning agent for a blanket of an offset printing machine excellent in the above has been proposed (for example, Patent Document 1).
According to such a blanket cleaning agent, petroleum hydrogenation treatment is performed using a metal catalyst for hydrogenation of an aromatic nucleus under conditions of a pressure of 30 to 100 kg / cm ² and a temperature of 100 to 300 ° C., A blanket cleaning agent comprising a hydrocarbon mixture solvent having an aromatic hydrocarbon content of 3% or less obtained by precision distillation and a boiling point in the range of 150 to 200 ° C.

Further, an impression cylinder cleaning agent that can easily remove impression cylinder stains in an offset printing machine has been proposed (for example, Patent Document 2).
More specifically, it is an emulsification type impression cylinder cleaner containing 10% by mass or more of a linear unsaturated fatty acid having 16 to 24 carbon atoms, and further containing an abrasive and water, preferably silicone. It is an emulsification type impression cylinder cleaning agent further containing a compound and a surfactant.

In addition, a cleaning composition containing propylene glycol ether, propylene glycol ether acetate, and water has been proposed (for example, Patent Document 3).
More specifically, although it is an example of an Example, it is a cleaning composition containing 25% by weight of propylene glycol monomethyl ether, 60% by weight of propylene glycol monomethyl ether acetate, and 15% by weight of water.

In addition, as a printing press cleaning agent, a printing press cleaning agent containing hydrocarbons, organic acid esters, a predetermined glycol compound, and water has been proposed (for example, Patent Document 4).
More specifically, a cleaning agent for a printing press containing 20 to 70% by weight of hydrocarbons, 5 to 55% by weight of organic acid ester, 20 to 70% by weight of propylene glycol monomethyl ether and the like, and 5 to 55% by weight of water. It is.

Moreover, printing which consists of the glycol compound which has a C1-C6 hydrocarbon group, the glycol compound which has a C8-C18 hydrocarbon group, a polyhydric alcohol, and water as a washing | cleaning agent for printing presses. Machine cleaning agents have been proposed (for example, Patent Document 5).
JP-A-6-184596 JP 2008-80636 A Japanese Patent Laid-Open No. 9-59682 Japanese Patent Application Laid-Open No. 11-80792 Japanese Patent No. 3698187

However, the blanket cleaning agent comprising the hydrocarbon mixture solvent disclosed in Patent Document 1 has an insufficient level of paper dust removability, and when the water roller or the like is cleaned, There was a problem in that oil droplets were formed on the printed matter, resulting in background stains on the printed matter.
Moreover, although the emulsification type impression cylinder cleaning agent disclosed in Patent Document 2 is excellent in paper dust removability, the contained abrasive is scattered on the printing plate, and the amount of ink adhering is reduced. There was a problem of missing.
Furthermore, the emulsification type impression cylinder cleaning agent disclosed in Patent Document 2, when a surfactant is added, the image line portion in the printing plate disappears, or when a silicone compound is added, it is scattered on the printing plate, There was also a problem that the amount of ink deposited decreased.

In addition, when the cleaning composition disclosed in Patent Document 3 is used as a cleaning agent for offset printing, there is a problem that a line part in a printing plate is easily damaged by a glycol compound or the like contained in the cleaning agent. It was.
In addition, the cleaning agent for printing press disclosed in Patent Document 4 contains hydrocarbons and organic acid esters mixed with the etchant via the water supply roller during cleaning to cause turbidity or generate oil droplets on the etchant surface. For example, when used for a long time, there is a problem that a printing defect such as background smearing occurs.
Further, in the cleaning agent disclosed in Patent Document 5, the tetrapropylene glycol isooctyl ether contained in the cleaning agent becomes mixed with the etchant via a water roller during cleaning and becomes turbid, or oil droplets are formed on the etchant surface. There was a problem that printing defects such as scumming occurred when used for a long time.

Therefore, as a result of earnest research to solve the above problems, the present inventors include an alkylene glycol ether having a predetermined water solubility and water, and the blending amount of the alkylene glycol ether with respect to water. By setting the value within a predetermined range, the ink and paper dust can be cleaned efficiently as a cleaning agent for an offset printing apparatus, and the printing line can be printed without damaging the image area. The present invention has been completed by finding that an offset print image of quality can be obtained and that the etchant does not become cloudy.
That is, the present invention provides a cleaning agent for offset printing that has an excellent balance of various properties, has excellent cleaning properties for conflicting inks and paper dust, and has little adverse effect on image areas and etchant in a printing plate. With the goal.

According to the present invention, there is provided an offset printing cleaning agent comprising an alkylene glycol ether and water, wherein the water solubility of the alkylene glycol ether is within the range of 3 to 20 parts by weight with respect to 100 parts by weight of water. And an offset printing detergent characterized in that the blending amount of the alkylene glycol ether is set to a value in the range of 400 to 2000 parts by weight with respect to 100 parts by weight of water.
That is, with such an offset printing cleaner, it is possible to efficiently wash the ink and paper dust, and a high-quality offset print image can be obtained without damaging the image area on the printing plate. And the etchant can be prevented from becoming cloudy.

In constituting the cleaning agent for offset printing of the present invention, the alkylene glycol ether is dipropylene glycol normal propyl ether, propylene glycol mononormal butyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol mononormal butyl ether, tripropylene glycol. It is preferably at least one selected from the group consisting of mononormal butyl ether and dipropylene glycol monoethylene glycol mononormal butyl ether.
Such a type of alkylene glycol ether not only has a relatively high boiling point and is excellent in handleability, but also can efficiently wash ink and paper powder, respectively.

In constituting the cleaning agent for offset printing of the present invention, it is preferable that at least one of a plate cylinder, a blanket, an ink roller, a water roller, or an impression cylinder in the offset printing apparatus is cleaned.
By being able to cope with such cleaning of the configuration of the offset printing apparatus, it is easy to use as a cleaning agent for offset printing, and the use value can be increased.

Another aspect of the present invention is a method of cleaning an offset printing apparatus using a cleaning agent for offset printing, and includes the following steps (1) to (2). It is a cleaning method.
(1) An alkylene glycol ether whose water solubility is within a range of 3 to 20 parts by weight with respect to 100 parts by weight of water is blended within a range of 400 to 2000 parts by weight with respect to 100 parts by weight of water. (2) Cleaning step for cleaning the offset printing device using the offset printing cleaning agent Cleaning an offset printing device using such an offset printing cleaning agent If it is a method, while being able to wash | clean ink and paper dust each efficiently, a high quality offset printing image is obtained without damaging the image part in a printing plate, and an etchant is not made turbid. Can be.

[First Embodiment]
1st Embodiment is the cleaning agent for offset printing containing alkylene glycol ether and water, Comprising: The water solubility of alkylene glycol ether is the range of 3-20 weight part with respect to 100 weight part of water. The offset printing cleaning agent is characterized in that the blending amount of the alkylene glycol ether is set to a value within the range of 400 to 2000 parts by weight with respect to 100 parts by weight of water.

1. Alkylene glycol ether (1) Type 1
As water solubility at room temperature (25 ° C.), an alkylene glycol ether that dissolves in a range of 3 to 20 parts by weight with respect to 100 parts by weight of water is used. That is, an alkylene glycol ether that exhibits semi-water solubility at room temperature (25 ° C.) is used.
The reason for this is that if it is an alkylene glycol ether exhibiting such semi-water solubility, the ink and paper powder can be washed efficiently by mixing with water at a predetermined ratio, and in the printing plate. This is because a high-quality offset printing image can be obtained without damaging the image area, and a cleaning agent for offset printing can be provided that hardly causes the etchant to become cloudy.

That is, when an alkylene glycol ether whose water solubility at room temperature (25 ° C.) is less than 3 parts by weight with respect to 100 parts by weight of water is difficult to dissolve in the etchant, the etchant is likely to be contaminated. Because.
On the other hand, when an alkylene glycol ether having a water solubility at room temperature (25 ° C.) of more than 20 parts by weight with respect to 100 parts by weight of water is used, the image area on the printing plate is damaged, thinned or lost. It is to do.
Accordingly, as water solubility at room temperature (25 ° C.), it is more preferable to use an alkylene glycol ether that dissolves in the range of 5 to 18 parts by weight with respect to 100 parts by weight of water, and it dissolves in the range of 6 to 15 parts by weight. More preferably, an alkylene glycol ether is used.

  By utilizing this semi-water-soluble property, ink can be washed even when water is still attached to the water roller. In other words, when a water-soluble alkylene glycol ether that is more than 20 parts by weight with respect to 100 parts by weight of water is used, water adhering to the water roller is added so that the solubility of the ink is increased. This is because it becomes poor and cleaning becomes difficult.

(2) Type 2
In addition, as the alkylene glycol ether exhibiting a predetermined water solubility (semi-water solubility), dipropylene glycol normal propyl ether, propylene glycol mononormal butyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol mononormal butyl ether, tripropylene glycol mono Examples thereof include normal butyl ether, dipropylene glycol monoethylene glycol mononormal butyl ether, and the like alone or in combination of two or more.

For example, propylene glycol mononormal butyl ether and propylene glycol monotertiary butyl ether are preferred alkylene glycol ethers because they do not damage the image area on the printing plate, have a relatively low boiling point, and are relatively quick to dry.
In other words, a blanket or impression cylinder is washed by impregnating a cleaning agent into waste cloth or the like, and the surface is washed by hand, or by spraying mist from a nozzle and wiping with a dry continuous cloth. In some cases, the surface of the water roller can be similarly cleaned by impregnating the waste cloth with a cleaning agent.

Further, dipropylene glycol normal propyl ether and dipropylene glycol mononormal butyl ether are preferable alkylene glycol ethers because they have a relatively medium boiling point without damaging the image area on the printing plate.
That is, dipropylene glycol normal propyl ether or dipropylene glycol mononormal butyl ether can be particularly suitably applied to the cleaning of the ink roller.

  Furthermore, tripropylene glycol mononormal butyl ether and dipropylene glycol monoethylene glycol mononormal butyl ether are preferable alkylene glycol ethers because they have a relatively high boiling point without damaging the image area on the printing plate. In other words, it can be applied to a machine that impregnates a cleaning liquid into a continuous cloth and presses the cloth against a blanket or impression cylinder for cleaning. Can be maintained.

(3) Boiling point Moreover, it is preferable to make the boiling point of alkylene glycol ether into the value within the range of 150-350 degreeC.
This is because the alkylene glycol ether having such a boiling point is not only easy to handle but also increases safety.
Therefore, the boiling point of the alkylene glycol ether is more preferably set to a value within the range of 150 to 280 ° C, and further preferably set to a value within the range of 150 to 250 ° C.

(4) Blending amount The blending amount of the alkylene glycol ether exhibiting a predetermined water solubility (semi-water solubility) is set to a value within the range of 400 to 2000 parts by weight with respect to 100 parts by weight of water. .
The reason for this is that when the amount of the alkylene glycol ether is less than 400 parts by weight, the effect of addition may not appear.
That is, it becomes difficult to efficiently wash the oleophilic ink, and in the offset printing apparatus, for example, when continuous roll paper is used, the risk of paper breakage increases.
On the other hand, when the blending amount of the alkylene glycol ether exceeds 2000 parts by weight, the blending amount of water is relatively decreased, and it becomes difficult to efficiently wash the paper dust. This is because the slipperiness decreases.
When slipperiness decreases in this way, when a person cleans a blanket or a plate cylinder using a cloth impregnated with an offset cleaning agent, there is a risk that a hand may be caught in the rotating cylinder,
When a blanket, a plate cylinder, or the like is automatically cleaned using a continuous cloth impregnated with an offset cleaner, chattering occurs on the contact surface, and good cleaning cannot be performed.
Further, by making the ink roller slippery at the time of cleaning, excessive friction between the rollers at the time of cleaning and between the blanket and the roller can be reduced, and the lifetime of the blanket and the ink roller can be extended.
Accordingly, the blending amount of the alkylene glycol ether exhibiting a predetermined water solubility (semi-water solubility) is preferably set to a value within the range of 500 to 1600 parts by weight with respect to 100 parts by weight of water, and 600 to 1400 parts by weight. More preferably, the value is within the range.

2. Water Also, by mixing water with the above-mentioned alkylene glycol alkyl ether in a predetermined amount, offset printing with excellent detergency of ink and paper dust and less adverse effect on image areas and etchant on the printing plate A cleaning agent can be provided.
Here, regarding the mixing ratio of water, as described above, it is preferable to determine the blending amount of the alkylene glycol ether to be a value within the range of 400 to 2000 parts by weight with respect to 100 parts by weight of water. It is more preferable to determine the value to be in the range of 500 to 1600 parts by weight, and it is even more preferable to determine the value to be in the range of 600 to 1400 parts by weight.

That is, the following characteristics can be obtained by blending a predetermined proportion of water.
1) Sliding of the blanket and the ink roller at the time of cleaning is imparted, and excessive friction between the rollers at the time of cleaning and between the blanket and the roller can be reduced, thereby extending the life of the blanket and the ink roller.
2) In the removal of paper dust, the washing effect can be enhanced by swelling starch or the like, which is a component of paper dust.

Therefore, when the content of water in the cleaning agent for offset printing is excessively reduced, the paper powder removability is lowered or the slipping becomes difficult.
On the other hand, if the water content in the cleaning agent for offset printing is excessively large, the ink cleaning property may be inferior, or in the offset printing apparatus, for example, when continuous roll paper is used, there is a risk of paper breakage. It is to increase.
In addition, by adjusting the content of water in the cleaning agent for offset printing, the flash point can be eliminated, and the safety can be further increased.
As a more specific example, the composition is 85 parts by weight of dipropylene glycol monoethylene glycol mononormal butyl ether and 15 parts by weight of water.

3. Surfactant Further, the cleaning agent for offset printing can contain a surfactant, but even in that case, the content of the surfactant is 3% by weight or less with respect to the total amount. It is preferable that
The reason for this is that such a predetermined amount of surfactant can provide a further balance of detergency with respect to ink and paper dust, and a high-quality offset printed image can be obtained.
That is, adding more than a predetermined amount may contaminate the etchant or affect the surface tension of the etchant, but such a predetermined amount of surfactant suppresses the occurrence of such problems. However, this is because a high-quality offset print image may be obtained.
Therefore, when the cleaning agent for offset printing contains a surfactant, the content of the surfactant is more preferably set to a value within the range of 0.01 to 2% by weight based on the total amount. More preferably, the value is within the range of 0.01 to 1% by weight.

  The type of the surfactant is not particularly limited, and is represented by, for example, acetylene alcohol, acetylene glycol, polyhydric alcohol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyhydric alcohol fatty acid ester, and the like. Nonionic surfactants are preferred.

4). Additives In addition, surface tension reducing agents (ethylene glycol monohexyl ether, etc.) are included in offset printing detergents to further adjust the surface tension, etc. of offset printing detergents, to provide more functionality or to provide long-term storage stability. ), Scale inhibitors and chelating agents (sodium gluconate, etc.), rust inhibitors (ammonium carbonate, etc.), acid neutralizers (tetraalkylammonium hydride, ammonia, etc.), alkali neutralizers (acetic acid, formic acid, hydrochloric acid, etc.) It is also preferable to add at least one of a redox agent (such as hydrogen peroxide), an antioxidant (such as butylhydrotoluene), and a colorant.
In this case, although depending on the type of additive, the additive amount of such additive is usually set to a value within the range of 0.005 to 5% by weight with respect to the total amount of cleaning agent for offset printing. preferable.

  In addition, water-soluble alkylene glycol alkyl ethers, alkylene glycol alkyl ether alkyl esters, alcohols, alcohol alkyl esters, and other water-soluble solvents may be used in a small amount, for example, the total amount. On the other hand, if it is a value of 20% by weight or less, it is also preferable to blend as an additive.

5). Various characteristics (1) Boiling point Moreover, when it has the boiling point of the cleaning agent for offset printing, it is preferable to make the boiling point into the value within the range of 100-350 degreeC.
The reason for this is that such a configuration increases safety and facilitates handling. Therefore, even when the cleaning agent is sprayed on the offset printing apparatus, the offset printing apparatus can be quickly and safely removed.
However, if the boiling point of the cleaning agent for offset printing becomes excessively high, the natural drying property may be significantly reduced.
Accordingly, the boiling point of the cleaning agent for offset printing is more preferably set to a value within the range of 100 to 280 ° C, and further preferably set to a value within the range of 100 to 250 ° C.
The boiling point of the cleaning agent for offset printing is adjusted to a value within a predetermined range by changing the content of the alkylene glycol alkyl ether (relative water content) or the type of the alkylene glycol alkyl ether used. be able to.

(2) Surface tension Moreover, it is preferable to make the surface tension of the cleaning agent for offset printing into the value within the range of 25-35 mN / m.
The reason for this is that by limiting the surface tension value of the cleaning agent for offset printing, the wettability of each component of the offset printing device can be further improved. Can be washed.
More specifically, when the surface tension of the cleaning agent for offset printing is less than 25 mN / m, the surface tension of the blanket after cleaning is reduced, water is likely to be mixed into the ink, and the printed surface is blurred. This is because it may occur.
On the other hand, when the surface tension of the cleaning agent for offset printing exceeds 35 mN / m, the wetting spread of the cleaning agent on the blanket is lowered, and the cleaning performance may be uneven.

Therefore, the surface tension of the cleaning agent for offset printing is more preferably set to a value within the range of 26 to 33 mN / m, and further preferably set to a value within the range of 28 to 32 mN / m.
As described above, the surface tension of the cleaning agent for offset printing is within a predetermined range depending on the content of the alkylene glycol alkyl ether (relative water content), the type of the alkylene glycol alkyl ether used, or the like. Can be adjusted to a value within.

(3) Flash point Moreover, when the cleaning agent for offset printing has a flash point, it is preferable to make the flash point into the value within the range of 21-140 degreeC.
The reason for this is that the ink adhering to the offset printing apparatus can be removed quickly and safely even if the cleaning agent is sprayed on the offset printing apparatus. Can do.
However, when the flash point of the cleaning agent for offset printing becomes excessively high, the natural drying property may be remarkably lowered.
Therefore, the flash point of the cleaning agent for offset printing is more preferably set to a value within the range of 21 to 140 ° C, and further preferably set to a value within the range of 41 to 100 ° C.
Further, by setting the flash point of the cleaning agent for offset printing to a value of 40 ° C. or higher, there is no legal restriction on explosion-proof equipment, so that the processing apparatus can be further reduced in size.
The flash point of the cleaning agent for offset printing is adjusted to a value within the specified range by changing the alkylene glycol alkyl ether content (relative water content) and the type of alkylene glycol alkyl ether used. can do.

[Second Embodiment]
The second embodiment is a method for cleaning an offset printing apparatus using a cleaning agent for offset printing, and includes the following steps (1) to (2). is there.
(1) An alkylene glycol ether whose water solubility is within a range of 3 to 20 parts by weight with respect to 100 parts by weight of water is blended within a range of 400 to 2000 parts by weight with respect to 100 parts by weight of water. (2) Cleaning process for cleaning the offset printing apparatus using the offset printing detergent

1. Adjustment Step In this adjustment step, a semi-water-soluble alkylene glycol ether and water are blended at a predetermined ratio to obtain a cleaning agent for offset printing.
The aspect of the cleaning agent for offset printing is as described in the first embodiment.

2. Cleaning process (1) Target for cleaning Targets offset printers. For example, FIG. 1 and FIG. 2 show typical offset printing apparatuses (for single-sided printing and double-sided printing) as targets.
That is, it is preferable that at least one of the plate cylinder 14, the blanket 12, the ink roller 16, the water roller 18, or the impression cylinder 13 in the offset printing apparatuses 10 and 30 shown in FIGS.
This is because by being able to cope with the cleaning of the configuration of such an offset printing apparatus, it is easy to use as a cleaning agent for offset printing, and the use value can be increased.
There are two types of offset printing devices: an offset sheet-fed device that prints a predetermined image on each sheet of paper, and an offset rotary device that prints roll paper at high speed. As one aspect of the printing apparatus, it is a cleaning target.

(2) Cleaning conditions The cleaning conditions of the offset printing apparatus are not particularly limited. For example, the offset printing detergent is sprayed, immersed in the offset printing detergent, or offset printing. A cloth impregnated with a cleaning agent may be rubbed against the components of the offset printing apparatus.

  For example, in the case of a cleaning agent for offset printing having a relatively fast drying property, more specifically, as an example, a cleaning agent for offset printing composed of 90% by weight of propylene glycol mononormal butyl ether and 10% by weight of water is used. In this case, when washing the blanket or the impression cylinder, it is preferable to impregnate the cloth with a cleaning agent for offset printing and wash it by hand, or spray a mist-like spray mist and wipe it off with the cloth.

  Further, such a relatively quick drying cleaning agent for offset printing can be preferably applied to the cleaning of the water roller, and can be cleaned well even if the water roller is still wet. Moreover, even when applied to the cleaning of the water roller, it is possible to obtain an effect that the cloudiness of the etchant is small.

  On the other hand, in the case of the cleaning agent for offset printing having relatively slow drying properties, more specifically, as an example, offset printing comprising 90% by weight of dipropylene glycol monoethylene glycol mononormal butyl ether and 10% by weight of water. In the case of a cleaning agent for cleaning, it is preferable to automatically wash a blanket or an impression cylinder by pressing a continuous cloth impregnated in advance with the blanket or impression cylinder.

  Hereinafter, based on an Example, this invention is demonstrated in detail.

[Example 1]
1. Preparation of cleaning agent for offset printing A cleaning composition for offset printing having a predetermined temperature was prepared as shown in Table 1. That is, 900 g of dipropylene glycol normal propyl ether (boiling point: 212 ° C., 19 parts by weight dissolved in 100 parts by weight of water) and 100 g of water in a 2 L lidded vessel equipped with a stirrer and a heating device. Were stored for 10 minutes using a stirrer to obtain a cleaning agent for offset printing of Example 1.

2. Evaluation of cleaning agent for offset printing (1) Evaluation of durability of printing plate (Evaluation 1)
The cleaning agent for offset printing was dropped on the image area of the printing plate used in the offset printing apparatus shown in FIG. 1, and left as it was for 30 minutes.
Next, the resistance evaluation of the printing plate with the cleaning agent for offset printing was visually performed according to the following criteria.
A: The disappearance of the image area is not observed at all, and there is no practical problem.
○: The disappearance of the image area is hardly observed, and there is no practical problem.
Δ: Part of the disappearance of the image area was observed, but this was practically acceptable.
X: The image area disappears and cannot be used practically.

(2) Detergency evaluation of water roller (Evaluation 2)
A predetermined image was continuously printed with an offset printing apparatus for 24 hours. Thereafter, the water roller to which the ink and the etchant were attached was hand-washed with a cloth impregnated with a cleaning agent for offset printing, and the cleaning performance of the water roller was visually evaluated according to the following criteria.
A: The ink adhering to the water roller can be washed and removed quickly with a light force.
○: A strong force is required to wash the ink adhering to the water roller, but the ink can be removed by washing.
(Triangle | delta): A strong force is required for wash | cleaning the ink adhering to a water roller, and most ink can be wash | cleaned and removed.
X: Even if it wash | cleans with a strong force, it is difficult to wash and remove the ink adhering to a water roller.

(3) Detergency evaluation of ink roller (Evaluation 3)
A predetermined image was continuously printed for one week using an offset printing apparatus. Thereafter, the evaluation of the detergency of the ink roller with the cleaning agent for offset printing was visually performed for each of the ink and the paper dust according to the following criteria.
That is, the cleaning performance evaluation is performed until a predetermined amount of cleaning agent for offset printing is continuously applied to the ink roll while the offset printing apparatus is in operation until the ink and paper dust are cleaned and removed from the ink roller. It depends on time.
For reference, FIGS. 3A and 3B show photographs of the surface state before and after cleaning the ink roller.
A: It can be removed by washing within 10 minutes.
○: Can be removed by washing within 15 minutes.
Δ: Can be removed by washing within 20 minutes.
X: It takes 20 minutes or more for the cleaning removal, or the cleaning cannot be removed.

(4) Blanket detergency (Evaluation 4)
In the offset printing apparatus, a predetermined image was printed for 2 days while appropriately cleaning the blanket using a petroleum-based cleaning agent (manufactured by Cosmo Petrotec, Petrosol P-1S).
Next, the blanket is wiped by hand with a cloth impregnated with the cleaning agent for offset printing, and the cleaning performance of the blanket with the cleaning agent for offset printing is evaluated visually according to the following criteria for each of ink and paper dust. went.
That is, while operating the offset printing apparatus, the blanket was wiped with a cloth impregnated with a cleaning agent for offset printing, and it was evaluated how many times the ink and paper dust could be washed and removed while the blanket was rotating.
For reference, FIGS. 4A to 4B show photographs of the surface state before and after cleaning the blanket.
A: It can be washed and removed by one rotation.
○: Washing and removal can be performed by two rotations.
(Triangle | delta): It can wash and remove by 3 rotations.
X: It takes 4 or more rotations for cleaning removal, or it cannot wash.

(5) Resistance evaluation of etchant (Evaluation 5)
After the water roller cleaning performance evaluation, the resistance of the etchant was evaluated while rotating the water roller, and the state of the water supply water vessel filled with the etchant was visually observed according to the following criteria.
A: The etchant is transparent as a whole.
○: The etchant is almost transparent as a whole.
Δ: The etchant is temporarily clouded as a whole, but becomes transparent immediately.
X: The etchant is cloudy and oil droplets are floating on the etchant surface.

(6) Paper break resistance evaluation (Evaluation 6)
Using an offset printing apparatus, a predetermined image was continuously printed on two coated paper rolls, and then a cycle for carrying out automatic blanket cleaning was set as one cycle, and five cycles were repeated. Then, the paper break resistance evaluation by the cleaning agent for offset printing was performed according to the following criteria.
A: There was no paper break even once in 5 cycles.
○: The paper was cut once during 5 cycles.
Δ: Paper was cut twice during 5 cycles.
X: The paper was cut three times or more during 5 cycles.

[Examples 2 to 7]
In Examples 2 to 7, based on Example 1, while preparing the cleaning agent for offset printing having the composition shown in Table 1, various properties were measured. The evaluation results are shown in Table 2.

  As shown in Table 1, in Example 2, as a semi-water-soluble alkylene glycol ether, a predetermined amount of propylene glycol mononormal butyl ether (boiling point: 170 ° C., 6 parts by weight dissolved in 100 parts by weight of water) Was used.

  In Example 3, a predetermined amount of propylene glycol monotertiary butyl ether (boiling point: 153 ° C., 17 parts by weight dissolved in 100 parts by weight of water) was used as the semi-water-soluble alkylene glycol ether.

  In Example 4, a predetermined amount of dipropylene glycol mononormal butyl ether (boiling point: 229 ° C., 5 parts by weight dissolved in 100 parts by weight of water) was used as the semi-water-soluble alkylene glycol ether.

  In Examples 5 and 6, as a semi-water-soluble alkylene glycol ether, a predetermined amount (80% by weight, 95% by weight) of ethylene glycol dipropylene glycol mononormal butyl ether (boiling point: 250 ° C. or more, 100 parts by weight of water) On the other hand, 8 parts by weight dissolved) was used.

  Furthermore, in Example 7, as a semi-water-soluble alkylene glycol ether, a predetermined amount of tripropylene glycol mononormal butyl ether (boiling point: 274 ° C., 3 parts by weight dissolved in 100 parts by weight of water) and dipropylene glycol monoethylene A mixture of glycol mononormal butyl ether (boiling point: 250 ° C. or higher, dissolved in 8 parts by weight with respect to 100 parts by weight of water) was used.

Evaluation 1: Printing plate resistance evaluation Evaluation 2: Water roller cleaning performance evaluation Evaluation 3: Ink roller cleaning performance evaluation Evaluation 4: Blanket cleaning performance evaluation Evaluation 5: Etch liquid resistance evaluation Evaluation 6: Paper break resistance evaluation

[Comparative Examples 1-6]
In Comparative Examples 1 to 6, based on Example 1, the cleaning compositions for offset printing having the composition shown in Table 1 were prepared, and various characteristics were measured. The evaluation results are shown in Table 2.
As shown in Table 1, in Comparative Examples 1 and 2, a predetermined amount (75% by weight, 97% by weight) of a semi-water-soluble dipropylene glycol monoethylene glycol mononormal butyl ether (boiling point 250 ° C.) was used as the alkylene glycol ether. As described above, 8 parts by weight dissolved in 100 parts by weight of water was used.

In Comparative Example 3, water-soluble dipropylene glycol monomethyl ether (boiling point 190 ° C., optionally dissolved in water) was used as the alkylene glycol ether.
In Comparative Example 4, as the alkylene glycol ether, slightly water-soluble diethylene glycol mono-2-ethylhexyl ether (boiling point 259 ° C., 1.7 parts dissolved in 100 parts by weight of water) was used.

In Comparative Example 5, propylene glycol mono-normal butyl ether and swazole 1000 (hydrocarbon solvent, boiling point 161-179 ° C., insoluble in water) were used.
In Comparative Example 6, only Swazol 1800 (hydrocarbon solvent, boiling point 195 to 245 ° C., insoluble in water) was used.

According to the present invention, by using a specific alkylene glycol ether and water at a predetermined ratio as a cleaning agent for offset printing, the ink and paper dust are excellent in cleaning properties, and the image area and the etchant in the printing plate It has become possible to provide a cleaning agent for offset printing that has less adverse effects on the surface.
That is, according to the present invention, the following effects can be obtained.
(1) A good detergency of ink and paper dust can be secured.
(2) Does not substantially contain an abrasive and does not physically damage the printing plate, blanket, ink roller, or the like.
(3) Since a predetermined detergency can be obtained even if it does not substantially contain oils such as completely water-insoluble hydrocarbons and vegetable oils, it can be mixed with etchant to become cloudy or become oil droplets on the liquid surface. Floating and less likely to contaminate etchant.
(4) Since a predetermined detergency can be obtained even if the surfactant is not substantially contained, the color of the image area in the printing plate can be reduced or lost, or the surface condition of the blanket can be changed. The surface tension of the etchant is not changed or the ink is excessively emulsified.

It is a figure provided in order to demonstrate an offset printing apparatus. It is a figure provided in order to demonstrate another offset printing apparatus. (A)-(b) is the surface photograph (magnification x200) before and behind washing for explaining the washing effect to the blanket by the cleaning agent for offset printing. (A)-(b) is the surface photograph (magnification x200) before and behind washing for explaining the washing effect to the ink roller by the cleaning agent for offset printing.

Explanation of symbols

10: single-sided offset printing apparatus 12, 12a, 12b: blanket 13: impression cylinder 14, 14a, 14b: printing plate 15a, 15b: ink apparatus (ink fountain)
16, 16a, 16b: ink rollers 18, 18a, 18b: water rollers 22, 22a, 22b: dampening device (water raising roller, water supply water ship)
30: Offset printing device for double-sided printing

Claims (4)

A cleaning agent for offset printing comprising alkylene glycol ether and water,
While making the water solubility of the said alkylene glycol ether into the value within the range of 3-20 weight part with respect to 100 weight part of water,
A cleaning agent for offset printing, wherein the blending amount of the alkylene glycol ether is set to a value in the range of 400 to 2000 parts by weight with respect to 100 parts by weight of the water.   The alkylene glycol ether is dipropylene glycol normal propyl ether, propylene glycol mononormal butyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol mononormal butyl ether, tripropylene glycol mononormal butyl ether, and dipropylene glycol monoethylene glycol mononormal butyl ether. The cleaning agent for offset printing according to claim 1, wherein the cleaning agent is at least one selected from the group consisting of:   The cleaning agent for offset printing according to claim 1 or 2, wherein at least one of a printing plate, a blanket, an ink roller, a water roller, or an impression cylinder in the offset printing apparatus is washed. A method for cleaning an offset printing apparatus using a cleaning agent for offset printing, comprising the following steps (1) to (2):
(1) An alkylene glycol ether whose water solubility is within a range of 3 to 20 parts by weight with respect to 100 parts by weight of water is blended within a range of 400 to 2000 parts by weight with respect to 100 parts by weight of water. (2) Cleaning step for cleaning the offset printing apparatus using the offset printing cleaning agent