JPS58177388A - Planographic method for metallic plate - Google Patents

Abstract

PURPOSE:To enable to prevent unfavorable printed conditions such as contamination in printing or water flow, by a method wherein damping water containing 0.5-25% of a water-miscible alcohol is used, the film thickness of damping water applied to a printing surface is set to be 0.2-2mum, and the thickness is controlled within a variation range of + or -0.1mum in accordance with the printed conditions. CONSTITUTION:A machine plate 4 provided with a fat-sensitive printing image part 2 and a hydrophilic non-image part 3 is fitted to the surface of a form cylinder 1, a tank 6 for containing damping water 5 containing 0.5-25% of a water-miscible alcohol is placed at a position in proximity to the form cylinder 1, and a chromo roller 7 is provided a part of which is immersed in damping water. A metering roller 8 is so provided as to make contact with the roller 7, and at a position on the downstream of the contact position, a water film 12a is formed on a form roller 10 by using a water film 11a formed on the roller 7, and further, a water film is transferred onto the hydrophilic non-image part 3 of the machine plate 4. By controlling the metering roller 8, the thickness of the water film is set to be 0.2-25mum, and is controlled within a variation range of + or -0.2mum in accordance with the printed condition. Accordingly, clear printing can be conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lithographic printing method on a metal plate, and more specifically, it is possible to print on a metal plate by preventing printing stains and water flow of solid image areas and halftone ink. This paper relates to an improved method that enables precise lithographic printing.

In the planographic printing method, a printing plate is used in which the drawing area and the non-printing area (background) are almost on the same plane, but these FIi#! The portion and the background have different properties, and the former is generally liposensitive and the latter is hydrophilic.

When printing using this printing plate, first water called dampening water is applied to the entire surface of the printing plate, but when a hydrophilic non-printing paint is applied, it adheres to the oil-sensitive printing area, but The ink is repelled by the water layer in the background.The printing plate, on which the ink layer is thus provided corresponding to the image area, is brought into direct contact with the printing surface, or the halftone plate is brought into contact with the rubber blank foot. After transferring the one-way ink layer to the blanket, the blanket is brought into contact with the printing surface to transfer the ink layer to the printing surface and lithographic printing is performed. In this printing plate for lithographic printing, The change in density of an image, that is, the gradation, is expressed by the size of the oil-sensitive halftone dots, and therefore the density of the image in printed matter is also expressed by the size of the ink halftone dots.

Conventionally, it has already been pointed out that the amount of dampening water applied is important in obtaining planographic prints with excellent gradation, clarity, and precision. At present, the control and management of dampening water still relies on the intuition of experts, and the optimal value for the amount of dampening water is also known, and the reproducibility of the amount of dampening water is not known. There were also very few administrative controls in place.

For example, the Molton method, the Dahlgren method, and the Ebitsuk method are known as methods for applying dampening water onto a printing plate. In the former Molton method, dampening water is applied by a roller covered with a cloth called a Molton, but in this method, the amount of water applied to the printing plate is controlled by the presence of the cloth. Have difficulty. Only [7
It's damp.

If too much water is used, the ink will become emulsified and its transferability will deteriorate, and the ink will float in the dampening water and be washed away, causing floating stains, causing the image to bleed and print, and vice versa. If there is too little dampening water, ink tends to adhere to non-image areas, resulting in smeared prints. In addition, in the latter Dahlgren method and Ebitsuku method, alcohol-containing dampening water from Impropyl Alcohol is pumped up with a chrome roller, the water film is controlled with a metering roller, and then the water film is transferred to an inking roller E. Afterwards, this roller applies a film of dampening water onto the printing plate. Although the Dahlgren method and the Evitsuk method make it easier to adjust the amount of dampening water applied compared to the Molton method, wettability is poor unless dampening water containing a high concentration of alcohol is used17. On the other hand, the presence of a high concentration of alcohol tends to cause emulsification of the ink, which tends to cause staining and water flow, which cannot be prevented.

In addition to the problems mentioned above, in the case of metal plate printing, material differences K have a significant effect. For example, ordinary lithographic printing processes use paper, and since the surface of this paper is fibrous, printing materials such as ink and dampening water are sucked into the fibrous structure, and the transferability of the ink is high. It is superior to Kamimetal in terms of printing suitability such as adhesion and adhesion. In addition, lithographic inks for metals have higher adhesive strength than those for paper, and printing conditions have become more severe. Furthermore, in the case of metal plates, large-sized drying equipment is required to fix the ink on the printed matter, and as a result, the printing environment tends to be high temperature and low humidity. Due to these factors, printing on metal plates requires different conditions than printing on paper.

Therefore, an object of the present invention is to provide a method that enables precise printing with good reproducibility on a metal plate without printing defects such as printing stains and water flow.

According to the present invention, dampening water is applied to a lithographic printing plate having an oil-sensitive printing area and a hydrophilic non-printing area, an ink layer is applied to the printing plate, and an ink layer is applied to the printing plate. In the lithographic printing method on metal surfaces, which consists of transferring the upper ink layer onto the metal plate, a dampening water with a water-miscible alcohol concentration of 0.5 to 25 inches is used as dampening water12. Water film thickness 0.2 to 2
μm, and adjust the water film thickness to ± according to the printing condition at that time.
The purpose of the present invention is to provide a method for controlling the width of 0.1 μm (7) and thereby preventing printing defects such as printing stains and water running.

1 and 2 for explaining the method of the present invention, a printing plate 4 having an oil-sensitive printing area 2 and a hydrophilic non-printing area 3 is attached to the surface of a printing cylinder 1. Ranel. A tank 6 containing dampening water 5 is provided near the periphery of the plate cylinder 1, and a chrome roller 7 is provided so as to be partially immersed in the dampening water 5 in the tank 6. However, in the Epic system shown in FIG.
is provided in place of. Although the roller arrangement in FIG. 2 is different from that in FIG. 1 as described above, the operation and effect are the same, so the explanation will be given below with reference to FIG. 1.

A metering roller 8 is provided so as to be in contact with this chrome roller 7, and furthermore, it is in contact with the chrome roller 7 at a position past the contact position with the metering roller 8, and is in contact with the printing plate 4.
A dipping roller 9 is provided so as to be in contact with both. An ink layer 10 is provided on the surface of the application roller 9.

As the dampening water 5 in the tank 6 rotates, it adheres to the surface of the chrome roller 7 and is drawn up. The water film 11α on the chrome roller 7 is divided into a film 11α and a water film 11b attached to the metering roller 8, and the water film 11α on the chrome roller 7 passes through the nip point with the dipping roller 9, and is then deposited on the ink layer 10 on the dipping roller 9. The adhesion E is also divided into a water film 12α and a water film 12b remaining on the chrome roller 7, and the water film 12α on the dipping roller 9 is transferred to the hydrophilic non-image area SK on the printing plate 4.

An important feature of the present invention is that a dampening solution containing 0.5 to 25% isopropyl alcohol is used as a dampening solution during planographic printing on the metal plate, and that the dampening solution is applied onto the printing plate. The present invention combines isopropyl alcohol (hereinafter simply referred to as IPA) in dampening water to a film thickness of 0.2 to 2 microns and is controlled within a width of ±0.1 micron depending on the printing condition at that time. (sometimes called)
By suppressing the content of water-miscible alcohols such as 0.5 to 25 cm, the thickness of dampening water applied on the printing plate can be reduced to 2 mm or less without impairing wetting properties etc. In lithographic printing on metal plates, the dampening water film thickness on the printing plate should be controlled to 2 microns or less;
Moreover, it is based on the new knowledge that by regulating the IPA concentration within the above range, it is possible to obtain printed matter that is clear and has excellent gradation without defects such as water flow, floating stains, and background stains.

First, if the IPA concentration in the dampening solution is made higher than 25%, the surface tension of the dampening solution will decrease too much, and as a result,
It is difficult to control the film thickness of the dampening solution on the printing plate to a value of 2 microns or less, and emulsification of the ink is likely to occur.
Floating stains and water flow are more likely to occur on printed matter.Moreover, when such water flow occurs in the case of halftone dot ink, the halftone dot area ratio between the printing plate and the printed matter becomes inconsistent, resulting in loss of gradation. This causes the inconvenience of being exposed.

These drawbacks are particularly noticeable in the case of metal plates, which are more affected by the amount of dampening water applied than in the case of paper. On the other hand, if the IPA concentration in the dampening solution is lower than 0.5, the wetting properties of the dampening solution will deteriorate, and as a result, ink stains in non-image areas, that is, scumming, will occur.
Become.

Also, if the dampening solution on the printing plate exceeds 2 microns,
In the case of metal plate printing, water flow and floating stains are likely to occur, and it is difficult to increase the amount of ink applied without further deteriorating gradation.

According to the present invention, as described above, by applying dampening water with a certain range of lPA concentration to a small film thickness on the printing plate, and controlling the film thickness to ±0.1 micron, Not only is it possible to obtain metal printed matter with no stains and excellent clarity and gradation, but the amount of dampening water applied is small, and the amount of printing ink used can be kept to a low level, making lithographic printing possible. The advantages of this method are that the cost of printing can be significantly reduced, printing defects such as printing stains and water running are eliminated, and metal printed matter with excellent clarity and gradation can be obtained.

IPA is most suitable as the water-miscible alcohol 12 in the dampening solution used in the present invention, but other monohydric alcohols may be used as long as they are water-miscible and have a surface tension-reducing effect.
Polyhydric alcohol can also be used to clean this leakage water.
H may be more acidic than neutral, and is generally preferably in the range of 5.5 to 6.5. It goes without saying that auxiliary agents known per se, such as phosphoric acid, phosphates, gum arabic, etc., may be blended into this dampening solution.

In the present invention, the film thickness of dampening water applied onto the printing plate is 0.2
Mechanical means and synthetic adjustment means are used to control the oyster in the 2 micron range and within ±0.1 micron. For example, the amount of coating can be adjusted by adjusting the gap or pressure between the chrome roller 7 and the metering roller 8 shown in FIGS. 1 and 2, and by adjusting the peripheral speed (rotational speed) of the chrome roller. This can be easily done by adjusting the Furthermore, the thickness of the dampening solution on the printing plate can be detected.
This can be easily done using infrared absorption by water molecules. A suitable example of such a detection mechanism is
73505, based on the signal from such a detection mechanism, the circumferential speed of the chrome roller, etc. is changed so that the dampening water film ff on the printing plate is always constant. Automatic control is also possible.

Furthermore, an important factor affecting the film thickness of the dampening solution is the IPA concentration in the dampening solution. That is, in the case of a relatively large film thickness within the above-mentioned range, a relatively high IPA concentration is allowed, but as the film thickness becomes smaller, the IPA concentration must also be lowered. This relationship can be viewed as a linear proportional relationship with a difference of l.

I can't support it.

In the present invention, the IpA concentration in the dampening solution is strictly controlled, and the Dahlgren method or the Ebitsu method is adopted to adjust the gap between the two rollers or the pressure contact force, or to adjust the circumferential speed of the rollers. and detecting the film thickness on the printing plate by infrared absorption spectroscopy, and controlling at least one of the change factors using this detection signal.
This makes it possible to control the film thickness on the printing plate within the range of 0.2 to 2 microns and within a width of ±01 microns.

Examples of metal plates used in the lithographic printing method of the present invention include, in addition to untreated rolled steel plates (black plates), plated steel plates such as surface-treated steel plates such as tin plate, galvanized steel plate, aluminized steel plate, and chrome-plated steel plate; Examples include chemically treated steel sheets such as electrolytic chromic acid treated steel sheets (TFS); chemically treated steel sheets such as phosphoric acid and/or chromic acid treated steel sheets, and light metal sheets such as aluminum foil and/or aluminum foil.

These metal plates can be subjected to lithographic printing in an uncoated state, but in the case of packaging containers, a coating film (undercoating film or printing base coat) made of clay-curing resin or thermoplastic resin is applied to the surface of the metal plate. In some cases, it may be desirable to provide a white coating (also known as a white coating) and print on this coating.

Historically, a laminate of a metal foil such as a luminescent foil and a plastic film can also be used for printing.

The lithographic printing method of the present invention is known per se, except for the points mentioned above, and can be carried out under known conditions. A commercially available adhesive with relatively high adhesive strength is used.

The ink image formed on the printing plate surface may be transferred directly to the metal plate, but it is generally preferable to transfer it to a rubber blanket and then transfer it from the rubber blanket to the metal plate for printing. ! [-i.

The invention is illustrated by the following example.

The area ratio of the example halftone dots is Ol (non-print area), 10 inches, 40 inches, 7
A tin-free paper coated with a white coating as a printing base using a lithographic printing plate with gradations of 0% and 100% (peta area) and the Dahlgren dampening water device shown in Figure 1. Offset printing was performed on a steel plate.

As dampening water, IPAQ degree 25, pH 5.5 was used (7).

The thickness of the dampening water film on the printing plate was detected using an infrared absorption spectrum detection device, and the clearance between the chrome roller 7 and the metering roller 8 and the chrome roller 7 were adjusted so that the film thickness of the dampening water became 2 microns. 7. By controlling the circumferential speed of the chrome roller 7 based on the detection signal, the film thickness on the printing plate was controlled to be ±0.1 micron from the set film thickness.

After applying the above-mentioned dampening water to the above-mentioned film thickness on the printing plate, ink for metal lithographic printing (Toyo Ink Manufacturing Co., Ltd. wytx85) was applied.
2) was applied so that the amount of ink was 8 microns, offset printing was performed on the tin-free steel (rL'S) board, and the printed TFS board was dried [7].

Interference micrographs were taken of this printing plate immediately after printing started and after 5 hours, and printing defects such as printing stains and water running were examined, but no printing defects occurred in either case. It was good.

[Brief explanation of drawings]

1 and 2 are schematic perspective views of a dampening solution applicator used in the present invention. 2 is the drawing area, 3 is the non-printing area, 4 is the printing plate, 5 is the wet 1 water, 7
is a chrome roller, 8 is a metering roller, 9 is a staking roller, 10 is an ink layer, 11α, 11b, 12α, 12h
indicate a water film, respectively. Patent applicant: Toyo Seikan Co., Ltd.

Claims (1)

[Claims] (1) Apply dampening water to a lithographic printing plate with oil-sensitive image areas and hydrophilic non-image areas, apply an ink layer to the printing plate, and apply dampening water to the ink layer on the printing plate. In the lithographic printing process on metal surfaces, which consists of transferring a layer onto a metal plate, a dampening solution with a water-miscible alcohol concentration of 0.5 to 25 mos is used as a dampening solution, and the thickness of the water plate on the plate surface is The water film thickness is set to 0.2 to 2 μm, and the water film thickness is adjusted to ±0.0 μm depending on the printing condition at that time. IJ1
7) A method of controlling the width of 1 liter and thereby preventing printing defects such as printing stains and water flow0