JPS61179778A - Offset printing method - Google Patents

Abstract

PURPOSE:To prevent an ink from being adhered to non-picture element parts of a plate cylinder even where a form damping roller of a damping device is used as it is for a long period of time, by a method wherein surfactant-containing water is used as damping water in an inking arrangement, and a form damping roller and a rubber roller are used to provide a W/O-type emulsified condition. CONSTITUTION:In the inking arrangement 12, an ink is supplied from an ink ductor 13 to a form roller 14, and is adhered to picture element parts of the plate cylinder 11. The damping device 5 comprises a water trough 16, a water fountain roller 17, a water ductor 18, a water distributing roller 19 and a rubber-made form damping roller 20. First, an ink is adhered from the plate cylinder 11 to the surface of the roller 20. Next, damping water is kneaded into the ink on the surface of the roller 20 to provide a W/O-type emulsified condition. Thereafter, the ink adhered to the picture element parts of the cylinder 11 is adhered to the surface of the roller 20 on making contact with the latter, but when the quantity of the ink on the surface of the roller 20 is increased, the ink on the surface of the roller 20 is reversely adhered to the picture element parts of the cylinder 11, so that an equilibrium state is reached between the cylinder 11 and the roller 20.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an offset printing method, and more particularly to an improvement in a water supply method.

"Prior Art and its Problems" As is well known, in an offset printing press, dampening water is applied to the non-image area of the plate cylinder using a water supply device consisting of a water base roller, a reciprocating roller, a leveling roller, a swimsuit roller, etc. Ink source roller, ink feed roller, ink replenishing roller,
Ink reciprocating rollers, ink deposition, apply ink to the image area of the plate cylinder using an inking device consisting of rollers, etc., transfer the ink adhered to the image area to the blanket cylinder, and then transfer it to the impression cylinder via the blanket cylinder. The ink is transferred to the paper surface to print.

Conventionally, in general offset printing machines.

As a swimsuit roller of a water supply device, a roller having a surface wrapped with a covering having good water retention properties, such as Molton, etc., has been used. However, with this offset printing machine, the ink from the first plate cylinder gradually adheres to the swimsuit roller, and this adhered ink gradually changes the amount of water on the swimsuit roller, so the amount of dampening water supplied must be adjusted slightly. It was necessary to do so. Furthermore, if the swimsuit roller becomes stained with ink, the ink will adhere to the non-image areas of the plate cylinder, so it is necessary to replace the molton etc. on the surface of the swimsuit roller from time to time.

Furthermore, water supply devices using rubber rollers as swimwear rollers are also known. In this device, the rotational speed of the swimsuit roller and the reciprocating roller is changed so that the surface of the swimsuit roller is always covered with a film of water, thereby preventing ink from adhering to the swimsuit roller. however,
Even in this device, it is not possible to completely prevent ink from adhering to the swimsuit roller, and there is a problem in that the ink adhering to the swimsuit roller changes the supply state of the dampening water.

Furthermore, a so-called Dahlgren apparatus is also known, in which one of the rollers of the inking device is a swimsuit roller, and the ink and dampening water form an emulsified state on the surface of the swimsuit roller. However, in this Dahlgren device, it is necessary to contain a lower alcohol such as isopropyl alcohol in the dampening water at a content considerably higher than the environmental standard (within 5%), for example, 15 to 20%, which may harm the health of the workers. There was that. Furthermore, since one roller is used for both the swimsuit roller and the ink coat roller, there is a problem that uneven printing is likely to occur.

``Object of the Invention'' The object of the present invention is to solve the above-mentioned problems of the prior art, to prevent ink from adhering to the non-image area of the plate cylinder even if the swimsuit roller of the water supply device is used as it is for a long period of time, and The object of the present invention is to provide a new offset printing method that does not harm the health of workers.

"Structure of the Invention" In the offset printing method according to the present invention, dampening water is applied to the non-image area of the plate cylinder by a water supply device consisting of a water fountain roller, a reciprocating roller, a leveling roller, a bathing roller, etc., and an inking device A method in which ink is applied to an image area of a plate cylinder and the ink adhering to one image area is transferred to a rubber cylinder, the dampening water containing a surfactant is used, and the dampening water is used as the swimsuit roller. A rubber roller is used to form a W/O emulsion of dampening water and ink on the surface of the swimsuit roller.

Therefore, in the present invention, ink from the plate cylinder adheres to the surface of the swimsuit roller, dampening water is supplied into the ink from the water source roller and the reciprocating roller, and the dampening water is kneaded into the ink. A W/O emulsion is formed on the surface of the swimsuit roller. Then, the emulsified swimsuit roller causes dampening water to adhere to the non-image area of the plate cylinder, and ink to adhere to the image area of the plate cylinder. Note that ink does not adhere to the non-image areas of the plate cylinder.The reason why the ink on the surface of the swimsuit roller does not adhere to the non-image areas of the plate cylinder is because the swimsuit roller is made of a rubber roller. This is because it has a stronger adhesion force to the swimsuit roller than the non-image area of the plate cylinder.

Further, according to the present invention, ink on the surface of the swimsuit roller does not adhere to the reciprocating roller and contaminate the dampening water.
This is because the surface of the reciprocating roller is made of a material that has a high affinity for water, such as chrome plating, so a film of dampening water is formed on the surface, making it difficult for ink to adhere to it.

Previously, it was thought that it was common sense to use swimsuit rollers in such a way that ink did not adhere to the surface.
In the present invention, ink is rather actively deposited on the surface of the swimwear roller, and dampening water is kneaded into the ink to emulsify it, so ink stains on the surface of the swimwear roller are no longer a problem. Therefore, there is no need to use replacement materials such as Molton for the swimsuit roller, and maintenance such as cleaning can be reduced, and work efficiency can be improved. Note that the ink that adheres to the swimsuit roller from the print area of the print cylinder and the ink that adheres to the print cylinder of the print cylinder from the swimsuit roller are in an equilibrium state, so there is always a certain amount of ink and moisture on the swimsuit roller surface. Water is attached to form a certain emulsified state.

In order to emulsify the dampening solution into the ink on the surface of the swimwear roller, it is necessary to add a surfactant to the dampening solution. Examples of such surfactants include "Pink 5" (trade name,
(manufactured by Matsui V.T.O. Printing Co., Ltd.) is preferred, and a dampening solution made by diluting this "Pink 5" 400 times forms an extremely good emulsified state when mixed into ink.

Also, when ink is applied to the surface of the swimsuit roller and dampening water is mixed into the ink and emulsified, only the dampening water adheres to the non-printing area of the plate cylinder and the ink is transferred to the non-printing area. In order to prevent adhesion, the material of the rubber on the surface of the swimsuit roller is also an issue.According to the inventor's experiments, a special rubber roller that is both lipophilic and tree-philic is preferable for the swimsuit roller. It has been found that good results can be obtained by using, for example, "32A30GK" (trade name, manufactured by Kinyosha Co., Ltd.).

Furthermore, in the present invention, it is preferable to rotate the reciprocating roller and the swimsuit roller in synchronization with the rotation of the plate cylinder.If the rotations of the reciprocating roller, the swimsuit roller, and the plate cylinder are changed from each other, the ink on the surface of the swimsuit roller is It becomes difficult to form a good emulsion with the dampening water mixed into the dampening solution.

``Embodiments of the Invention'' FIG. 1 shows an example of an apparatus for carrying out the offset printing method according to the present invention. In FIG. A non-image area with high affinity and an image area with high affinity for ink are formed. Reference numeral 12 denotes an inking device, in which ink is supplied from an ink reciprocating roller 13 to a roller 14 so that the ink adheres to the image area of the plate cylinder 11 by the roller 14. Note that the ink source roller, ink feed roller, ink mixing roller, etc. are omitted in the figure. 15 is a water supply device, which includes a dampening water tank 18, a brush type water source roller 171, a reciprocating roller 18 whose surface is chrome plated, and a leveling roller 19. It consists of a swimsuit roller 20. The water source roller 17 transfers dampening water to the reciprocating roller 1
8, and is driven independently by a DC motor to adjust the amount of dampening water supplied by increasing or decreasing the rotation. The reciprocating roller 18 rotates in synchronization with the rotation of the plate cylinder 11,
At the same time, dampening water is kneaded into the swimsuit roller 20 by reciprocating in the axial direction. The leveling roller 18 retains the dampening water and smooths it out, and is made of a rubber roller with Molton wrapped around its surface. The swimsuit roller 20 is made of a rubber roller such as 32A30GK J (trade name, manufactured by Kinyosha Co., Ltd.), and rotates simultaneously in contact with the printing cylinder l! and the reciprocating roller 18.

In the offset printing method according to the present invention, for example, in the above-mentioned apparatus, printing is performed using dampening water made by diluting "Pink 5" 400 times. First, ink is attached to the surface of the swimsuit roller 20 from the plate cylinder 11. . Then, the dampening water is kneaded into the ink on the surface of the swimsuit roller 20 from the water base roller 17 via the reciprocating roller 18 to form a W/O type emulsified state. When the dampening water dispersed in the ink on the surface of the wet roller 20 comes into contact with the first printing cylinder 11, it adheres to the non-image area.

At this time, the ink strongly adheres to the rubber surface of the swimsuit roller 20, so it does not adhere to the non-printing area of the first plate cylinder 11, and the ink also adheres to the reciprocating roller 18 whose surface is covered with dampening water. Note that the ink that has adhered to the image area of the plate cylinder 11 will adhere to the surface of the swimsuit roller 20 when it comes into contact with the swimsuit roller 20, but if the amount of ink on the surface of the swimsuit roller 20 increases, the ink will not adhere to the swimsuit roller 20. Since the ink on the surface of the roller 20 adheres to the printing area of the plate cylinder 11, a so-called equilibrium state is formed between the two, and there is no problem caused by excessive ink adhering to the surface of the swimsuit roller 20. After dampening water is applied to the non-image area of the plate cylinder 11, the inking device 12
The ink is applied to the image area, and the ink in the image area is transferred to a rubber cylinder (not shown). Thereafter, printing is performed in the same manner as normal on-seven set printing. In this way, in the present invention, even if the swimsuit roller 20 is used continuously for a long period of time, a good printing condition is maintained, and maintenance such as cleaning and maintenance of the swimsuit roller 20 is extremely small. Since the amount of dampening water taken in is stable, there is no need to delicately adjust the amount of dampening water supplied during use.

FIG. 2 shows another example of an apparatus for carrying out the offset printing method according to the invention. In this device, the water supply device! 5 Mizumoto Laura! 7' is a roller whose surface is plated with chrome, and a calling roller 21 is interposed between this water head roller 17° and the reciprocating roller 18.

The calling roller 21 is made of a rubber roller wrapped with Molton, and is mechanically swung to move the water head roller 17 degrees.
Water is supplied to the reciprocating roller 18. The rest of the configuration is similar to the device shown in FIG.

FIG. 3 shows a further embodiment of the apparatus for carrying out the offset printing method according to the invention. In this device, the water source roller 17'' of the water supply device 15 is made of a rubber roller, rotates in contact with the reciprocating roller 18, and supplies dampening water from the dampening water tank!6 to the reciprocating roller 18.Other configurations is similar to the device shown in FIG.

"Effects of the Invention" As explained above, according to the present invention, dampening water containing a surfactant is used, a rubber roller is used as the swimwear roller, and the dampening water and ink are applied to the surface of the swimwear roller. Since it was made to form an emulsified state of type 10,
The supply of dampening water from the wet roller to the non-image area of the plate cylinder is performed by dampening water emulsified in ink. In addition, the ink that adheres to the swimwear roller from the printing area of the plate cylinder and the ink that adheres to the printing area of the printing cylinder from the swimsuit roller are in equilibrium,
Since a certain amount of ink always adheres to the swimsuit roller, the emulsified state of the ink and dampening water can be maintained constant. Furthermore, the ink on the swimsuit roller strongly adheres to the rubber surface of the swimsuit roller, so it will not be transferred to the non-image area of the plate cylinder or the reciprocating roller. A good printing condition can be maintained even after a long period of use, and work efficiency can be improved by significantly reducing the need for cleaning and maintenance of the swimsuit roller. Further, since the supply state of the dampening water is constant, it becomes easy to adjust the supply amount of the dampening water.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the offset printing method according to the present invention, FIG. 2 is a schematic diagram showing another example of the apparatus for implementing the offset printing method according to the present invention, and FIG. The figure is a schematic diagram showing still another example of an apparatus for carrying out the offset printing method according to the present invention. In the figure, 11 is a plate cylinder, 12 is an inking device, 13 is an ink reciprocating roller, 14 is an ink deposition roller, 15 is a water supply device,
18 is a dampening water tank, 17.17'', 17'' are water source rollers, 18 is a reciprocating roller, 19 is a leveling roller, 20 is a bathing roller, and 21 is a calling roller.

Claims (2)

[Claims] (1) Dampening water is applied to the non-image area of the plate cylinder by a water supply device consisting of a water head roller, reciprocating roller, leveling roller, bathing roller, etc., and ink is applied to the image area of the plate cylinder by an inking device. In an offset printing method in which the ink adhering to the image area is transferred to a rubber cylinder, the dampening water contains a surfactant, the swimwear roller is a rubber roller, and the dampening water is applied to the surface of the swimwear roller. An offset printing method characterized by forming a W/O emulsion of dampening water and ink. (2) The offset printing method according to claim 1, in which the reciprocating roller and the bathing roller are rotated in synchronization with the rotation of the plate cylinder.