JP2008062455A - Printing method of seamless can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method of a seamless can which uses a lithographic plate of a type dispensing with dampening water and enables high-density reproduction and excellent flattening of a solid part without impairing precise and gradual tone reproduction which are excellent features of the lithographic plate of this type. <P>SOLUTION: In the printing method of the seamless can, printing ink is transferred onto a blanket sequentially from printing plates mounted on a plurality of plate cylinders and the ink transferred onto the blanket is transferred onto the seamless can. Herein ink for the lithographic plate of the type dispensing with dampening water is used as the printing ink, while the lithographic plate of the type dispensing with dampening water or a letterpress is mounted on the individual plate cylinders, and the ink on the blanket transferred from the letterpress is pressed by a non-image area of the lithographic plate of this type mounted on the plate cylinder behind the letterpress. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing method for a seamless can, and more particularly, high density reproduction and good solid portion crushing without impairing fine and gentle gradation reproduction, which is an excellent feature of a dampening-free lithographic plate. The present invention relates to a method for printing a seamless can.

Conventionally, for printing on seamless cans, a combination of a printing plate such as a lithographic plate and a relief plate and a blanket for receiving an ink layer from the printing plate and transferring it to the body of the can body is used.
In recent years, printing using a lithographic plate enables fine printing with halftone dots, and it is possible to reproduce a pattern with rich colors and shades, such as a color photograph, in a seamless can. Unnecessary lithographic plates are used (for example, Patent Document 1).
A dampening water-free lithographic plate is one in which an ink receiving portion and an ink non-receiving portion are formed on a flat surface, and the ink non-receiving portion is formed without application of dampening water. Instead of a hydrophilic surface that accepts water, a non-adhesive film such as silicone rubber that becomes the ink repellent surface is used, and the non-adhesive film is removed or masked part becomes the ink receiving part. The ink adhering to the ink receiving portion is transferred to a blanket, and then the blanket image is transferred to a seamless can for printing.

In such a dampening water-free type lithographic plate, since the portion where the silicone resin layer of the plate surface is concave is the image line portion, it is a lithographic plate in which ink is held in a dent of several μm in thickness, In the case of reproducing an image at a high density, it is necessary to reproduce the ink more than the depth of the dent.
In addition, a method of performing offset printing on a two-piece can body using both a dampening water-free lithographic plate and a resin relief plate has been proposed (Patent Document 2).

JP 2002-36710 A JP 2001-138383 A

However, if the ink is thickened and the ink is excessively supplied in this way, the ink adheres to the silicone resin layer forming the non-image area, resulting in plate surface stains (ground stains). Therefore, there is a limitation on the amount of ink. In lithographic printing without dampening water, printing is performed using the ink resilience of the silicone resin layer, so the ink viscosity is set high, the ink is easy to mottling, sufficient density reproduction, and solid printing. There is a problem that the part cannot be crushed.
In the case of using a relief printing plate, the ink can be thickened without causing the problem of soiling as in the case of a fountain solution-free lithographic plate, and an image having a high density and a texture can be formed. However, there is a problem that unevenness due to marginal peculiar to a relief plate or thickening of halftone dots occurs, and the pattern of the plate cannot be reproduced in detail.
Furthermore, in the method using both the dampening water-free lithographic printing plate and the resin relief printing described in Patent Document 2, printing is performed so that the colors do not overlap from the viewpoint of preventing the ink of the ink supply unit from becoming cloudy. As a result, there is a problem that color loss tends to occur in the image.

  Accordingly, an object of the present invention is to provide a fountain solution capable of reproducing a high density and forming a solid solid portion without impairing the fine and gentle gradation reproduction, which is an excellent feature of the fountain solution-free lithographic plate. It is to provide a method for printing a seamless can using an unnecessary lithographic plate.

According to the present invention, in a seamless can printing method, printing ink is sequentially transferred onto a blanket from printing plates mounted on a plurality of plate cylinders, and the printing ink transferred onto the blanket is transferred to a seamless can. Further, a fountain solution-free lithographic ink is used as the printing ink, and a fountain solution-free lithographic plate or relief plate is mounted on the plurality of plate cylinders, and the ink on the blanket transferred from the relief plate is used as the relief printing plate. There is provided a printing method for a seamless can characterized by pressing at a non-image portion of a dampening water-free lithographic plate mounted on a later plate cylinder.
In the printing method of the present invention,
1. The relief plate is mounted on the first half of the cylinders,
2. The viscosity of the ink supplied to the letterpress is adjusted by temperature control,
3. The letterpress is a resin letterpress,
Is preferred.
Another object of the present invention is to provide a seamless can printed by the above printing method.

In the seamless can printing method of the present invention, a fountain solution-free lithographic plate capable of reproducing a fine and smooth gradation in a high-density seamless can and forming a good solid crushing. It is to provide a printing method for the seamless can used.
The seamless can printed by the printing method of the present invention reproduces a fine and gentle gradation at a high density, has less color loss, and has an improved commercial value.

In the seamless can printing method of the present invention, a printing ink is sequentially transferred from a printing plate mounted on a plurality of plate cylinders onto a blanket, and the printing ink transferred onto the blanket is transferred to a seamless can. In the printing method of the can, a fountain solution-free lithographic ink is used as the printing ink, and a fountain solution-free lithographic plate or a relief plate is mounted on each of the plurality of plate cylinders and is transferred from the relief plate It is an important feature that the ink is pressed at a non-image portion of a dampening water-free lithographic plate mounted on a plate cylinder after the relief printing plate.
In the present invention, all-color fountain-free lithographic ink is used, and both fountain-free lithographic plates and letterpress are used as printing plates to be mounted on multiple plate cylinders. Depending on the image part to be printed, a dampening water-free lithographic plate or a combination of letterpress and dampening water-free lithographic plates is used to form an ink image on the blanket, which requires a characteristic reproduction of the dampening water-free lithographic plate. An image is formed with a lithographic plate that does not require fountain solution, and a thick plate of ink on the blanket is provided on the blanket by a relief plate that can be thickened because there is little plate surface contamination. Then, by pressing this with a non-image area of the dampening-free lithographic plate, the marginal peculiar to the relief printing plate can be crushed even if a high-viscosity dampening-water-free lithographic ink is used. Yes, no dampening solution required Lithographic to without damaging the print reproducibility of such excellent color and shading of specific, it's becomes possible to realize also the reproducibility of the high concentration of pattern.

That is, as shown in FIG. 1, in the dampening water-free type lithographic plate, the spread of the ink 3 other than the ink receiving portion 2 formed on the plate surface 1 is caused by the non-ink receiving portion 4 formed by a silicone layer or the like. For this reason, in the dampening water-free lithographic plate, the halftone dots of the ink transferred from the blanket 5 are not thickened, and a fine image can be obtained. On the other hand, as shown in FIG. 2, the relief printing plate can deposit a larger amount of ink than the planographic printing plate, but the ink adheres to the side surfaces other than the upper surface of the dot projections 6 formed on the plate surface 1. Then, the adhered ink (marginal 7) is transferred to the blanket 5 in a state where it spreads outward from the upper surface of the dot projection, and this is transferred to the outer surface of the seamless can. While the thickness increases outward from the point and fine reproducibility is difficult, the solid portion can be crushed at a high concentration.
From this point of view, in the present invention, a relief printing plate is used together with a dampening-free lithographic printing plate, and as shown in FIG. 3, the ink on the blanket transferred by the relief printing plate is mounted on the plate cylinder after the relief printing plate. It is possible to crush the marginal that causes the thickening of halftone dots by pressing at the non-image area of the fountain solution-free lithographic plate, which cannot be realized with conventional fountain solution-free lithographic plates Therefore, it is possible to form a high density reproducibility and a good solid crushing.

  In general, when printing with a combination of planographic and letterpress in seamless can printing, it is necessary to print so that the colors of the ink supply unit do not overlap from the viewpoint of preventing the ink of the ink supply unit from becoming cloudy. In the present invention, the ink transferred onto the blanket by the relief plate is pressed at the non-image area of the lithographic plate, and the relief image or the lithographic image area portion attached to the plate cylinder afterwards. Is set without contacting the ink already transferred onto the blanket, so that not only the color turbidity but also the color omission is effectively prevented.

  Further, in the present invention, a fountain solution-free lithographic ink having a high ink viscosity is used, but the plate cylinder used for the relief printing plate is free from smearing, so that the roller of the ink supply unit corresponding to the relief printing plate The temperature of the ink is adjusted so as to increase, and the viscosity of the ink can be lowered in the range where ink turbidity or background smear does not occur in the subsequent lithographic printing, thereby improving the transferability.

[printing]
In the printing method of the seamless can of the present invention, as described above, the ink on the blanket transferred from the relief printing plate using the dampening solution unnecessary type printing plate and the dampening solution unnecessary type printing plate and the relief printing plate is used. Can be pressed by a non-image portion of a waterless lithographic plate mounted on a plate cylinder after the relief plate, and the printing plate, blanket and seamless can are driven in contact at a constant speed in the forward direction. Can be printed.
FIG. 4 shows an arrangement of an example of a printing machine used in the printing method of the present invention. This printing machine 10 is roughly divided into a plate cylinder 11, a blanket wheel 12, and a mandrel 13 for transporting seamless cans. Composed. A dampening water-free type lithographic plate 14 a or a relief plate 14 b is attached to the surface of the plate cylinder 11 as a printing plate 14, and a blanket 15 is attached to the blanket hole 12. The seamless can 8 is held so as to be able to rotate on the mandrel 13 via the seamless can supply unit 16 and is held so as to contact the blanket 15. In order to supply printing ink to the printing plate 14, for example, a multi-roll or anilox ink supply unit 17 is provided.
In the example of the printing press shown in FIG. 4, a total of eight plate cylinders 11 and ink supply units 17 are arranged around the blanket wheel 12, and can be printed in a single color or in multiple colors of two to eight colors. Printing is performed. Further, each of the plate cylinders 11 is provided with a dampening water-free type lithographic plate 14a or a relief plate 14b, and the ink on the blanket transferred by the relief plate does not require a dampening water attached to the plate cylinder after the relief plate. The dampening water-free type lithographic plate and the relief plate are arranged so as to be pressed at the non-image area of the type lithographic plate.

Printing ink is supplied from the ink supply unit 17 to the dampening water-free lithographic plate 14 a or the relief plate 14 b, and the halftone dots of the printing plate and the ink on the image portion are transferred to the blanket 15. The dot-like and image-lined ink transferred from the relief plate 14b onto the blanket 15 is pressed by the non-image area of the dampening water-free type plate 14a attached to the plate cylinder 11 after the relief plate 14b. The In the present invention, dampening water-free lithographic ink is used for all plate cylinders, so that the ink transferred onto the blanket by the relief plate is pressed against the non-image area of the dampening water-free lithographic plate. However, it is effectively prevented that the non-image portion of the dampening water-free lithographic plate is deteriorated.
On the blanket 15, ink of each color is transferred from the dampening water-free lithographic plate 14a or the relief plate 14b. Seamless cans are obtained.
In the present invention, as described with reference to FIGS. 2 and 3, the ink transferred from the relief printing plate to the blanket is used as the dampening water-free type attached to the printing drum after the printing drum provided with the relief printing plate. As long as the plate can be pressed by the lithographic plate, the arrangement of the printing plates mounted on the plate cylinder is not particularly limited, and various combinations are possible.
For example, a relief printing plate is mounted only on the first plate cylinder 11a, and a fountain solution-free type plate is mounted on the other plate cylinders. The transferred ink may be pressed, or a relief printing plate and a dampening-free lithographic plate are mounted alternately, and the dampening solution-free printing plate immediately after the relief printing presses the ink transferred onto the blanket by the immediately preceding relief printing plate You can also do it. It is preferable that the relief plate is mounted on the plate cylinder in the first half portion among the plurality of plate cylinders. In this way, a plurality of dampening water-free lithographic plates can be mounted in the latter half, so that the ink transferred from the relief plate can be pressed a plurality of times, and the solid portion can be crushed.

  In addition, as described above, in the present invention, all-color dampening water-free lithographic ink is used, and dampening-water-free lithographic ink is printed by utilizing the ink resilience of the silicone resin layer. The ink viscosity is set to a high level.However, in the plate cylinder using a relief printing plate, the ink surface can be made low because the plate surface is not soiled, thereby improving the transferability of the ink. At the same time, there are no noticeable irregularities. Therefore, in such a case, in the ink supply unit that supplies ink to the relief printing plate, it is preferable to increase the temperature adjustment setting of the roller to lower the viscosity of the ink.

The dampening water-free lithographic plate used in the present invention comprises an ink receiving part and an ink non-receiving part on which water is not applied on a support, and the ink non-receiving part is generally formed from a silicone layer. On the other hand, the ink receiving portion is made of a photocurable or photodetachable photosensitive resin layer.
Such fountain solution-free lithographic plates and methods for producing the same are already known. For example, JP-B-54-26923, JP-B-61-54222, JP-B-7-96646, JP-A-2-77750 It is described in. In the present invention, any known fountain solution-free lithographic plate can be used for the purpose of the present invention.
Further, as the relief plate used in the present invention, a conventionally known one can be used in which an image portion in which image lines such as characters are mainly formed in a convex shape can be used, but in the present invention, it is a resin relief plate. It is preferable that the plate is easy to manufacture.

[Printing ink]
In the present invention, it is important to use a dampening water-free lithographic printing ink. As an important characteristic of printing ink, it is indispensable that it has ink transferability. However, as shown above, the waterless type lithographic ink is also required to have resilience to the silicone layer.
In the present invention, the reason why the fountain solution-free lithographic printing ink is used in the plate cylinder on which the relief plate is mounted is that the fountain solution-free lithographic ink is used in the fountain solution-free lithographic ink non-receptive layer (non-printing layer). The ink transferred from the relief plate onto the blanket is pressed with the non-image area of the lithographic plate that does not require water. However, the printing ink peels off without sticking to the non-image area, and the non-image area does not deteriorate.
Such fountain solution-free lithographic printing ink contains a vehicle, an additive and a colorant, and oil, resin, solvent, plasticizer and the like are used as the vehicle. These vehicles and the thickener described below are selected and blended so as to have a viscosity in the range described below.
On the other hand, as additives, natural or synthetic waxes, drying agents, dispersing agents, wetting agents, crosslinking agents, gelling agents, thickening agents, anti-skinning agents, stabilizers, matting agents, antifoaming agents, A photopolymerization initiator or the like is used. As the colorant, known dyes, pigments or toners are used.

  The ink vehicle used may be heat curable or ultraviolet curable. The thermosetting type is not limited to the following examples, but ink using an alkyd type or polyester type vehicle is suitable. The alkyd-type or polyester-type vehicle comprises (i) at least one of polyhydric alcohols such as glycerin, pentaerythritol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, sorbitol, mannitol, trimethylolpropane, and (ii) Polybasic acids such as phthalic anhydride, isophthalic acid, maleic acid, fumaric acid, sebacic acid, adipic acid, citric acid, tartaric acid, malic acid, diphenic acid, 1,8-naphthalic acid, terpene oil, rosin , And optionally, (iii) fatty oils or fatty acids such as linseed oil, soybean oil, egoma oil, fish oil, tung oil, sunflower oil, walnut oil, pear oil, castor oil, dehydrated castor oil, Distilled fatty acids, cottonseed oil, coconut oil, or these This resin is modified with fatty acid or monoglyceride of fatty acid. This resin is further modified with rosin, non-drying fatty acid, urea melamine resin, drying oil fatty acid, carboxylic acid resin, maleic acid resin, ester rosin, etc. It is also used in the form of natural resin modification.

  As the ultraviolet cationic polymerization type, for example, a combination of an ultraviolet curable epoxy resin and a photocationic polymerization catalyst is used. The ultraviolet curable epoxy resin contains an epoxy resin component having an alicyclic group in the molecule and an adjacent carbon atom of the alicyclic group forming an oxirane ring. For example, at least 1 in the molecule An epoxy compound having an epoxycycloalkane group, for example, an epoxycyclohexane ring, an epoxycyclopentane ring, or the like is used alone or in combination. Suitable examples include, but are not limited to, vinylcyclohexene diepoxide, vinylcyclohexene monoepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 2- (3,4-epoxycyclohexyl). -5,5-spiro-3,4-epoxy) cyclohexane-m-dioxane, bis (3,4-epoxycyclohexyl) adipate, limonene dioxide and the like. The cationic ultraviolet polymerization initiator used in combination with the epoxy resin is one that decomposes by ultraviolet rays, releases a Lewis acid, and this Lewis acid has a function of polymerizing an epoxy group. For example, aromatic iodonium And salts, aromatic sulfonium salts, aromatic selenium salts, aromatic diazonium salts, and the like.

As the viscosity of the fountain solution-free lithographic ink used in the present invention, the ink viscosity supplied to the fountain solution-free lithographic plate is preferably in the range of 30 to 70 Pa · s. By being in the above range, print stains due to background stains are generated, and ink transfer can be improved. The viscosity here is a viscosity measured using a cone plate viscometer at a temperature of 30 ° C. and a shear rate of 100 / s.
In order to maintain the ink viscosity within the above range, various rolls that directly or indirectly support the printing ink, for example, a plate cylinder roll, an inking roll of a printing unit, a blanket wheel, and the like are adjusted. For the purpose of temperature control, it is effective to pass cooling water or temperature-controlled water into each roll or to provide a self-cooling mechanism by rotation.

In the seamless can which has been printed by the printing method of the present invention, the finishing varnish is coated on the ink layer. As shown in FIG. 4, the finish varnish is applied by using an applicator roller 18 coated with the varnish and bringing the applicator roller 18 into contact with the outer surface of the seamless can 7 on which printing has been performed. The same is done. The seamless can 8 coated with the finishing varnish is discharged from the printing machine by the seamless can discharge unit 19. The formation of the printing ink layer and the formation of the finishing varnish film can be performed in a so-called wet-on-wet relationship. After the printing ink layer is cured, the formation of the finishing varnish film is performed by a so-called wet It can also be done in an on-dry relationship.
As the finishing varnish to be applied on the printing ink layer, it is preferable to use a water-based finishing varnish among those generally called finishing varnishes in the field of can printing. As the finishing varnish, among the resins described for the printing ink, those having excellent transparency and scratch resistance are used without the addition of pigments or colorants. Any of these may be used. In general, self-emulsifying or activator emulsifying thermosetting acrylic resins, acrylic epoxy resins, acrylic amino resins and the like are suitable for this purpose. The thickness of the finishing varnish layer is not particularly limited as long as the printing ink layer is sufficiently protected, but it is generally preferably 3 to 10 μm, particularly 4 to 6 μm.

In the case of heat curing, the printing ink layer and the finishing varnish layer can be cured at a temperature of 180 to 220 ° C. On the other hand, in the case of ultraviolet curing, light having a wavelength of 200 to 430 nm, particularly 240 to 420 nm is generally used as the ultraviolet light including the near ultraviolet region. As the ultraviolet light source, a halide lamp, a high pressure mercury lamp, a low pressure mercury lamp, or the like is used. Since the thickness of the coating layer is small, it is an advantage that less energy is required for curing, and an energy of 500 to 5000 joules / m ² is generally sufficient.

[Seamless cans]
The printing method of the present invention can be applied to any seamless can. Seamless cans are generally formed by drawing or deep drawing of metal or coated metal, drawn ironing, etc., and it is customary to print the outer surface of the molded can body. In addition, the present invention is useful.

(Example 1)
At a temperature of 30 ° C. and a shear rate of 100 / s, a fountain solution-free lithographic ink having a viscosity of 50 Pa · s measured using a cone plate viscometer is used. A dampening water-free type lithographic plate was mounted on the plate cylinder, white printing was performed with a resin relief plate, and then an image formed by pressing at a non-image area of the dampening water-free type lithographic plate was observed. The results are shown in FIG.
(Comparative Example 1)
An image was formed in the same manner as in Example 1 except that a dampening water-free type lithographic plate was mounted on both the first plate cylinder and the second plate cylinder. The results are shown in FIG.

As is clear from FIG. 5, Example 1 in which the image formed by pressing the image formed with the resin relief printing plate with the non-image portion of the dampening water-free lithographic plate has a missing portion that appears to be a dot. There is little crushing of the ink, and a clear and solid white solid portion is obtained. In addition, although the plate after printing was observed, plate cylinder stain | pollution | contamination did not generate | occur | produce.
On the other hand, as is clear from FIG. 6, it is clear that Comparative Example 1 consisting only of the dampening water-free lithographic plate does not have a clear white solid portion as compared with the present invention.

(Reference example)
Using a dampening water-free lithographic ink having a viscosity of 50 Pa · s measured using a cone plate viscometer at a temperature of 30 ° C. and a shear rate of 100 / s, the first plate cylinder and the second plate cylinder Both are equipped with a dampening water-free type lithographic plate, white printing is performed with the dampening water-free type lithographic plate mounted on the first plate cylinder, and a dampening water-free type lithographic plate mounted on the second plate cylinder is not printed. The image shown in FIG. 7 was obtained by pressing this at the line part (Reference Example 1).
An image shown in FIG. 7 was obtained in the same manner as in Reference Example 1 except that a resin relief plate was mounted on the first plate cylinder (Reference Example 2).
Enlarged views of the same part (the part circled in FIG. 7) of the images of Reference Example 1 and Reference Example 2 are shown in FIGS. 8 and 9, respectively.

As is apparent from FIG. 8, when both the first and second plate cylinders are printed using a dampening-free lithographic plate, the edge of the character is reproduced sharply, but the white density However, it can be seen that such a combination of plates is suitable for fine reproduction.
On the other hand, as is apparent from FIG. 9, when printing is performed on the first printing cylinder using a resin relief printing plate and a dampening water-free lithographic printing plate on the second printing cylinder, the white density is high but the edges of the characters are sharp. Rather, it turns out that such a combination of plates is suitable for a solid portion requiring density.

It is a figure explaining the state of the ink transferred to the blanket by the dampening water unnecessary type lithographic plate. It is a figure explaining the state of the ink transferred to the blanket by the letterpress. It is a figure explaining the state which pressed the ink transferred to the blanket by the letterpress in the non-image part of the dampening water unnecessary type lithographic plate. It is a figure which shows an example of the printing machine used for the printing method of this invention. 2 is a diagram illustrating an image obtained in Example 1. FIG. 6 is a diagram illustrating an image obtained in Comparative Example 1. FIG. It is a figure which shows the image obtained by the reference example. It is a figure which expands and shows the image obtained in the reference example 1 partially. It is a figure which expands and shows the image obtained in Reference Example 2 partially.

Explanation of symbols

1 plate surface, 2 ink receiving portion, 3 ink, 4 non-ink receiving portion, 5 blanket, 6 dot projection, 7 marginal, 8 seamless can, 10 printing machine, 11 printing cylinder, 12 blanket wheel, 13 mandrel, 14 printing plate 14a Dampening-free lithographic plate,
14b Letterpress, 15 blanket, 16 seamless can supply unit, 17 ink supply unit, 18 applicator roller, 19 seamless can discharge unit.

Claims (5)

  In a seamless can printing method, printing ink is sequentially transferred from a printing plate mounted on a plurality of plate cylinders onto a blanket, and the printing ink transferred onto the blanket is transferred to a seamless can. A stencil-free type lithographic ink is used, and each of the plurality of plate cylinders is provided with a fountain solution-free type lithographic plate or a relief plate, and the ink on the blanket transferred from the relief plate is transferred to the plate after the relief plate. A printing method for a seamless can characterized by pressing at a non-image portion of a dampening water-free lithographic plate mounted on a cylinder.   The method for printing a seamless can according to claim 1, wherein the relief plate is mounted on a plate cylinder in the first half of a plurality of plate cylinders.   The seamless can printing method according to claim 1, wherein the viscosity of the ink supplied to the relief printing plate is adjusted by temperature control.   The method for printing a seamless can according to any one of claims 1 to 3, wherein the letterpress is a resin letterpress.   A seamless can printed by the printing method according to claim 1.

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