JP2006182824A - Detergent for printing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detergent for a printing machine which involves no risk of damaging a printing area of a printing plate and therefore gives a clear printed matter even after repeated cleaning by dissolving a problem that a surfactant damages the printing area of the printing plate and is liable to cause white-off on printing by repeated printing and cleaning when a detergent containing a surfactant or a hydrocarbon is used for cleaning and removing inks or paper powders deposited on a blanket or the like of the printing machine which cause defective transfer of inks or cause deterioration in printing qualities by scraping off the printing area part of an offset printing plate. <P>SOLUTION: The detergent for the printing machine comprises (A) 40-90 wt% of at least one hydrophobic solvent selected from among hydrocarbons and monohydric alcohol fatty acid esters, (B) 1-40 wt% of at least one surfactant selected from among fatty acid alkanol amides and polyhydric alcohol fatty acid esters, and (C) 1-20 wt% of water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cleaning agent for a printing press.

  Ink and paper dust are likely to adhere to a blanket of a printing press such as an offset printing press. Especially when high viscosity ink is used, paper dust entangled with ink increases. Ink or paper dust deposited on a blanket or the like may cause ink transfer failure, or may cause image quality to deteriorate due to scraping off the image line portion of the offset printing plate. For this reason, waste of ink and paper dust deposited and deposited on the blanket, ink roller, etc. is washed and removed during printing, at the end of printing, and at the time of plate replacement. The cleaning agent for the printing press used here can clean the residue of ink and paper dust and does not affect the image area of the offset printing plate especially when used during printing or at the end of printing. It is desirable to be. As a cleaning agent for such a printing press, an aliphatic ester, a glycol ester and a polyoxyalkylene alkyl ether as an emulsifier (Patent Document 1), a glycol ether, an aromatic hydrocarbon, and a ketone ( Patent Document 2) and the like are known.

JP 2000-8079 A JP 2000-44995 A

  Conventionally known cleaning agents for printing presses can wash ink and have little influence on PS negative plates. However, in recent years, in newspaper printing, digital direct plate making from the conventional PS negative plate, so-called Computer-To- Printing using a plate (hereinafter referred to as CTP) printing plate has increased and it has been difficult to cope with this. PS negative plate is a printing plate with a photo-curing type photosensitive layer that is exposed to a negative film, and the photosensitive layer that is exposed to light is cured to form an image area, and the portion that is not exposed to light is dissolved and removed with a developer. However, since it requires skill in film handling and double-baking of the color plate, such as spots and fogging due to adhesion of dust etc. during plate making, shortening the plate making time by labor saving process, labor saving, In consideration of labor saving and cost reduction due to filmless, a CTP printing plate is used in which a plate material having a photosensitive layer is exposed directly from a computer without making a film to make a plate.

  However, the CTP printing plate is susceptible to the influence of some of the cleaning agent raw materials because the light energy at the time of exposure is smaller than that of the conventional PS negative plate and the components of the photosensitive layer are different. If a detergent containing polyoxyalkylene alkyl ether is used as an emulsifier, the image area of the CTP printing plate is likely to be affected by the surfactant, and color loss may occur during printing if repeated printing and washing are performed. There was a problem. In addition, the cleaning agent for a printing press described in Patent Document 2 does not cause a change in density or thickness in the printed image area even when the CTP printing plate is printed again after washing with an ink roller. The purpose is to provide a cleaning agent capable of obtaining a printed material that faithfully reproduces the image area, but since it contains glycol ethers, the image area may be damaged when adhering to a CTP printing plate in large quantities. was there. On the other hand, PS positive plates are mainly used in commercial printing, and as with CTP printing plates, they are susceptible to the influence of some detergent raw materials and the image area may be affected. Hydrocarbon solvents and fluorinated solvents have been used for cleaning such as the above. However, since hydrocarbon solvents have a low boiling point and can easily volatilize and cause a flammable explosion, they are designated as dangerous materials by the Fire Service Act and may cause solvent poisoning. Moreover, since a fluorine-type solvent destroys an ozone layer, future use is difficult.

  The present invention has been made for the purpose of solving the above-mentioned problems, and is a cleaning agent for a printing press that does not cause the image area to be damaged even when a large amount of cleaning liquid adheres to the CTP printing plate and PS positive plate. The purpose is to provide.

That is, the present invention
(1) at least one hydrophobic solvent selected from (A) hydrocarbons and monohydric alcohol fatty acid esters, and at least selected from (B) fatty acid alkanolamides and polyhydric alcohol fatty acid esters A cleaning agent for a printing press comprising 1 to 40% by weight of a surfactant and (C) 1 to 20% by weight of water,
(2) The cleaning agent for a printing press according to the above (1) having a pH of 5.5 to 8.5,
Is the gist.

  The cleaning agent for a printing press according to the present invention has a possibility that the image area of the plate is not affected even when the cleaning liquid is scattered and adhered to the printing plate for CTP or PS positive plate at the time of ink roller cleaning. However, it is possible to obtain a clear printed matter with no color loss.

As the hydrocarbons of group (A) constituting the cleaning agent for a printing press of the present invention, any of paraffin, olefin, alkyne, cycloparaffin, cycloolefin, and aromatic hydrocarbon can be used, but the flash point is high. The thing of 60 degreeC or more is preferable. Moreover, the thing whose boiling point is 300 degrees C (1.013 * 10 < ⁵ > Pa) or less is preferable. Examples of hydrocarbons having a flash point of 60 ° C. or higher and a boiling point of 300 ° C. or lower (1.013 × 10 ⁵ Pa) include C _{11 to} C ₁₈ paraffins, C _{11 to} C ₁₈ olefins, cyclodecane, cyclododecane, etc. And cycloolefins such as cycloparaffin, cyclononene, cyclodecene, and cyclododecene. Further, among these hydrocarbons, C _{11 to} C ₁₄ paraffins and C _{14 to} C ₁₆ olefins are more preferable. Examples of monohydric alcohol fatty acid esters include esters of C _{8 to} C ₁₈ alcohols and C _{8 to} C ₁₈ saturated or unsaturated fatty acids. Specific examples include lauryl alcohol lauric acid esters and octyl alcohols. Examples thereof include lauric acid ester and octyl alcohol oleic acid ester. Furthermore, among these monohydric alcohol fatty acid esters, esters of C ₁₂ -C ₁₈ alcohols with C ₁₂ -C ₁₈ saturated or unsaturated fatty acids are more preferred. (A) Group hydrocarbons and monohydric alcohol fatty acid esters can be used in a suitable mixture of two or more.

On the other hand, the fatty acid alkanolamide of group (B) includes an amide reaction product of a C _{8 to} C ₁₈ saturated or unsaturated fatty acid and an alkanolamine. Examples of the alkanolamine include monoethanolamine, diethanolamine, monoisopropanolamine, ethyl monoethanolamine, and butyl monoethanolamine. Specific examples of fatty acid alkanolamides include lauric acid monoethanolamide, coconut oil fatty acid ethyl monoethanolamide, capric acid monoisopropanolamide, myristic acid diethanolamide, butyl stearate monoethanolamide, oleic acid monoisopropanolamide, and the like. Can be mentioned. Among these, an amide reaction product of lauric acid, coconut oil fatty acid and alkanolamine is preferable. As the polyhydric alcohol fatty acid ester, either a partial ester or a complete ester of a polyhydric alcohol and a fatty acid can be used. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, glycerin, diglycerin, triglycerin, pentaerythritol, sorbitol, and the like. More specific examples of polyhydric alcohol fatty acid esters include ethylene glycol monooleate, propylene glycol monolaurate, trimethylolpropane monopalmitate, pentaerythritol monomyristate, sorbitol monooleate, glycerin monoolein Acid ester, glycerol dioleate, glycerol trioleate, etc. are mentioned. Among the polyhydric alcohol esters, monoesters and diesters of glycerin and sorbitol with C _{12 to} C ₁₈ saturated or unsaturated fatty acids are preferable. The fatty acid alkanolamides and / or polyhydric alcohol fatty acid esters of group (B) can be used in appropriate mixture.

  The cleaning agent for a printing press of the present invention comprises 40 to 90% by weight of a hydrophobic solvent selected from the hydrocarbons and / or monohydric alcohol fatty acid ester of the group (A), a fatty acid alkanolamide of the group (B) and 1 to 40% by weight of at least one surfactant selected from polyhydric alcohol fatty acid esters and (C) 1 to 20% by weight of water (provided that the hydrophobic solvent of group (A), ( B) Group surfactant and water total 100% by weight). Preferably, it is 70 to 85% by weight of the hydrophobic solvent in the (A) group, 5 to 20% by weight of the surfactant in the (B) group, and (C) 5 to 15% by weight of water. When the proportion of the hydrophobic solvent in the group (A) is less than 40% by weight, the cleaning performance with respect to the ink is lowered and the viscosity of the cleaning liquid is reduced to the blanket due to high viscosity, and the cleaning agent remains on the blanket surface for printing. If the quality deteriorates and exceeds 90% by weight, the possibility of an accident such as ignition is increased, and the cleaning performance for paper dust is lowered. On the other hand, when the proportion of the surfactant in the group (B) is less than 1% by weight, the cleaning properties are lowered, and the dispersion of each cleaning agent component is non-uniform and easily separated, and when it exceeds 40% by weight. Due to the high viscosity, the cleaning agent diffusibility to the blanket is reduced, and the cleaning agent remains on the blanket surface, resulting in a decrease in printing quality. Also, if the water ratio is less than 1% by weight, the possibility of an accident such as ignition increases and the washability for paper dust decreases. Paper breakage occurs during washing.

  The cleaning agent for printing presses of the present invention preferably has a pH of 5.5 to 8.5, more preferably 6.5 to 7.5. If the pH is less than 5.5, the dispersion of each cleaning agent component may be non-uniform and may cause separation, and if it exceeds 8.5, the image area of the CTP printing plate and PS positive plate will be destroyed. As a result, the print quality may be degraded. When adding acid, organic acid such as lactic acid or malic acid or fatty acid such as lauric acid or oleic acid is used when adding acid, and organic alkali such as diethanolamine or triethanolamine is used when adding alkali. Use to adjust. Inorganic acids such as hydrochloric acid and sulfuric acid, and inorganic alkalis such as sodium hydroxide and potassium hydroxide are preferred because the components in the cleaning agent are non-uniformly dispersed and easily separated, and the printing press may be corroded. Absent.

  The cleaning agent for printing presses of the present invention may have an emulsion form, or may have a form in which hydrocarbons or monohydric alcohol fatty acid esters and water are solubilized. In view of adaptation to the method of use and stability over time, those having a form in which hydrocarbons and water are solubilized are preferable.

  In order to improve the rust prevention property, the rust preventive agent can be added to the cleaning agent of the present invention within a range not impairing the intended purpose of the present invention. Examples of the rust inhibitor include sodium benzoate, BHT, tocopherol and the like. Two or more kinds of rust preventives can be mixed and used.

  The cleaning agent for printing presses of the present invention can be used for cleaning various printing presses such as offset printing presses and screen printing presses and their plate copper, blanket copper, printing plate, ink roller, etc. It has excellent cleaning properties, and there is no risk of deterioration in print quality due to remaining on a blanket, etc., and it is an epoch-making product that does not destroy the image line area of CTP printing plates and PS positive plates for offset printing. Since it has an effect, it is particularly suitable as a cleaning agent for an offset printing press.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, cleaning agents A to H having the following composition were used, and in the comparative examples, the following cleaning agents I to P were used.

Detergent A (present invention): Paraffin 90% by weight of C _12, coconut oil fatty acid monoethanolamide 4 wt%, diglycerol monooleate 4 wt%, consists of a 2% by weight of water, the pH at lactate Cleaning agent adjusted to 6.0.

Detergent B (present invention): Paraffin 40 wt% of C _14, 20% by weight coconut oil fatty acid diethanolamide, sorbitol monooleate 20% by weight, consists of a 20% by weight of water, the pH at oleate 7 Cleaning agent adjusted to .5.

Detergent C (present invention product): alpha-olefins 78 weight% of C _12, glyceryl monooleate 2% by weight, water 20% by weight detergent pH 6.5 consisting of.

Cleaning agent D (product of the present invention): C ₁₄ α-olefin 78% by weight, lauric acid diethanolamide 10% by weight, sorbitol dioleic acid ester 10% by weight, water 2% by weight. Cleaning agent adjusted to 7.3.

Cleaning agent E (product of the present invention): 30% by weight of C ₁₁ paraffin, 30% by weight of lauryl alcohol octyl acid ester, 10% by weight of lauric acid monoisopropanolamide, 10% by weight of sorbitol monolauric acid ester, 20% by weight of water A detergent whose pH is adjusted to 8.2 with lauric acid.

Cleaning agent F (product of the present invention): 35% by weight of C ₁₈ paraffin, 40% by weight of oleyl alcohol oleate, 7% by weight of stearic monoethanolamide, 8% by weight of glycerol dioleate, and 10% by weight of water A cleaning agent whose pH is adjusted to 6.8 with oleic acid.

Detergent G (present invention): Paraffin 75 wt% of C _14, monoethanolamide stearate 7% by weight, glycerin dioleate ester 8 wt%, consists of a 10% by weight of water, the pH with hydrochloric acid 5. Cleaning agent adjusted to 0.

Cleaning agent H (product of the present invention): A cleaning agent having a pH of 9.0, comprising 75% by weight of C ₁₄ olefin, 7% by weight of oleic acid monoethanolamide, 8% by weight of diglycerin oleate, and 10% by weight of water. .

Detergent I (comparative product): alpha-olefins 40 weight% of C _12, octyl alcohol 35 wt% oleic acid ester, 10 wt% lauric acid monoethanolamide, glyceryl mono-laurate 15% by weight and cleaning agent comprising.

Detergents J (comparative product): alpha-olefins 55 weight% of C _16, stearic acid diethanolamide 10 wt%, sorbitol monolaurate ester 10 wt% composed of a 25 wt% water, the pH at stearate 8. Cleaning agent adjusted to 0.

Detergent K (comparative product): becomes paraffin 65% by weight of C _12, lauryl alcohol stearate 30 wt%, from 2 wt% oleic acid diethanolamide, sorbitol dioleate ester 1 wt%, 2 wt% of water, A detergent whose pH is adjusted to 7.0 with oxalic acid.

Detergents L (comparative product): Paraffin 30 wt% of C _16, oleate monoethanolamide 25 wt%, diglycerol oleate 25% by weight, consists of a 20% by weight of water, the pH at succinic acid 7. Cleaning agent adjusted to 5.

Cleaning agent M (comparative product): 75% by weight of diethylene glycol monohexyl ether, 7% by weight of lauric acid diethanolamide, 8% by weight of sorbitol dilauric acid ester, and 10% by weight of water. The pH was adjusted to 8.3 with lactic acid. Adjusted cleaning agent.

Detergents N (comparative product): alpha-olefins 20 weight% of C _12, lauryl alcohol laurate 40% by weight of polyoxyethylene (7 mol) lauryl ether 30 wt%, composed of a 10 wt% aqueous citric acid A detergent whose pH was adjusted to 7.0.

Cleaning agent O (comparative product): kerosene cleaning agent P (comparative product): diethylene glycol monobutyl ether.

Examples 1-8, Comparative Examples 1-8
The cleaning properties of the cleaning agents A to P and the influence on the CTP printing plate, PS positive plate, PS negative plate and rubber were examined as follows. Table 1 shows the types and results of the cleaning agents used. The detergency was obtained by applying 0.1 g of a mixture of 80 parts by weight of printing ink (blue) and 20 parts by weight of paper powder to a sample piece (8 cm × 8 cm) prepared from a rubber blanket for an offset printing press. , Wipe the blanket with a non-woven fabric (10 cm x 10 cm non-woven fabric impregnated with 3 g of cleaning agent), observe the remaining ink and paper dust on the blanket after wiping, evaluated.

Evaluation criteria for detergency ◎ ・ ・ No ink or paper dust remains.
○ ・ Slight ink and paper dust remains.
Δ: Partially residual ink and paper dust are observed.
× ・ ・ Much ink and paper powder remain.

The effect on the CTP printing plate, PS positive plate, and PS negative plate was determined by dropping 0.5 ml of the cleaning agent on the plate and determining the degree of destruction of the image area of the plate 20 minutes after the dropping according to the following criteria. did.
○ ・ ・ No destruction of the image area.
Δ: Slight destruction of the image area is observed.
× ・ ・ The degree of destruction of the image area is large.

  The impact on rubber (swellability of rubber) was as follows: rubber blanket pieces (2 cm x 3 cm), NBR and fluoro rubber rubber packing (both 19 mm in diameter) each as a sample, and each sample at 25 ° C Immerse in a cleaning agent for 48 hours, measure the weight before immersion in the cleaning agent and the weight after immersion in the cleaning agent for 48 hours, and determine the swelling property of rubber based on the degree of swelling determined by the following formula (1). Evaluation based on the criteria. In addition, the average value of the measured value of two samples was employ | adopted for the degree of swelling.

(Equation 1)
Swelling degree (%) = sample weight after immersion / sample weight before immersion × 100 (1)

Evaluation criteria for rubber swellability ○ ・ ・ Swelling degree is 100% or more and less than 110% Δ ・ ・ Swelling degree is 110% or more and less than 120% × ・ ・ Swelling degree is 120% or more

  Moreover, the paper cutting property of each cleaning agent, the corrosiveness evaluation with respect to metal, and the evaluation of the appearance of the cleaning agent were evaluated by the following methods. The results are shown in Table 1.

Evaluation of paper breakage After folding one page of newspaper into two, open the folded newspaper and apply the cleaning agent evenly to the left and right sides of 1cm around the crease (0.5g coating weight). The load when the newspaper breaks when a weight that is fixed to one side that is balanced with the crease and the newspaper is suspended vertically and a uniform load is applied to the lower part of the newspaper is suspended below the fold. Based on the following criteria.
○ ・ ・ Newspaper breaks with a load of 10 kg or more.
△ ・ ・ Newspaper breaks with a load of 8-10kg.
× ·· Newspaper breaks with a load of less than 8 kg.

Evaluation of corrosiveness to metal An iron plate (2 cm × 5 cm) was immersed in a cleaning agent at 25 ° C. for 1 week, and the surface state of the iron plate was observed and evaluated according to the following criteria.
○ ・ ・ There is no surface change and no rust is observed.
△ ・ ・ Partial rusting is observed.
× ・ ・ Rust is observed on the whole.

Appearance evaluation of cleaning agent Observe the state of cleaning agent,
○ ・ ・ Stable and good appearance without separation or precipitation.
Δ ··· Slightly separable.
× ・ ・ There is separation and precipitation.
As an evaluation.

Claims (2)

(A) Hydrocarbons, at least one hydrophobic solvent selected from monohydric alcohol fatty acid esters, 40 to 90% by weight; (B) fatty acid alkanolamides, at least one selected from polyhydric alcohol fatty acid esters A cleaning agent for a printing press comprising 1 to 40% by weight of a surfactant and (C) 1 to 20% by weight of water. The cleaning agent for a printing press according to claim 1, having a pH of 5.5 to 8.5.