JP2847163B2 - Intaglio printing plate and its plate making method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intaglio printing plate used in intaglio printing, which is mainly used for printing securities such as banknotes and government bonds, and a plate making method thereof.

[Prior Art] In ordinary intaglio printing, a metal plate created by engraving or etching or a metal plate copied from this is used. When printing, first press the ink into the concave image area, wipe off the ink on the non-image area (this is called wiping), and then place printing paper on the printing plate and apply pressure to form the concave image area. Transferring ink to paper.

When performing intaglio printing on the front and back, printing is first performed on one side, and after the ink has dried, printing is performed on the other side.

[Problems to be solved by the invention]

At present, in printing of securities and the like, it is common to perform intaglio printing, but in the case of intaglio printing, ink in the non-image area is wiped off by wiping, and an aqueous solvent (this is called a wiping liquid). Has been dissolved and discarded. Wiping such as the fact that much of the ink is discarded without being used, the method of discarding the wiped ink, the reduction in printing durability of the printing plate by wiping, the selection of wiping liquid, the selection of wiping material, etc. There are still a number of issues in the work that need to be improved.

Further, since it takes a considerably long time to produce an intaglio printing plate surface, there is a problem that it is very inefficient for use in short run printing.

In order to solve the above-mentioned drawbacks, intaglio printing without wiping is the most desirable, but for that purpose, ink is not attached to non-image areas, and ink is applied only to image areas. An intaglio printing plate is required.

In addition, when performing intaglio printing on the front and back sides, printing twice on the front and back sides as described above is extremely inefficient, and the paper is stretched due to high printing pressure, and the printing on the front and back sides becomes poor. However, it is pointed out that the swelling of the ink of the intaglio printing printed on the paper is crushed. In order to solve such a drawback, simultaneous printing on both sides is desirable.However, if simultaneous printing on both sides is performed using a printing plate made of an inelastic material such as metal, high printing pressure during printing will result. However, there are many cases where the printing line is damaged, and there is a disadvantage that the image line is cut off at a portion where the image line is roughly overlapped on the front and back sides. However, by using an elastic body as the plate material, at a lower printing pressure than before,
Simultaneous front and back printing can be performed without damage to the paper and without breaks in the image. However, there is a problem that the elastic body itself is relatively soft and easily scratched because of its relatively soft surface, so that sufficient printing durability cannot be obtained as compared with a metal plate surface.

For this reason, various surface treatment methods have been considered to improve the abrasion resistance.However, the conventional surface treatment method covers not only the non-image area but also the image area, and the image shape changes. And the ink acceptability deteriorates.

The object of the present invention is to solve the problems at the time of the wiping step as described above or to improve the durability of the printing plate surface by treating only the non-image portion of the intaglio printing plate surface made of an elastic body with the coating composition. Things.

[Means for solving the problem]

The present invention relates to a new intaglio plate and a plate making method for forming a coating composition layer only on the surface of the non-image area of the intaglio plate surface made of a resin material by a photomechanical technique, and an RTV silicone rubber as the coating composition. The intaglio printing without wiping can be performed by depositing only on the image area by using, and the ultraviolet curable polyfunctional acrylic hard coating agent is used as a coating composition to improve the printing surface. Durability can be improved.

[Action]

When the non-image area of the intaglio plate surface made of elastic material is covered with silicone rubber, ink does not adhere to the non-image area and ink is applied only to the image area, enabling intaglio printing without a wiping process. Become.

Further, when the non-image area is treated with the hard coat agent, the abrasion resistance at the time of wiping is superior to that of the untreated part, so that the durability of the printing plate is improved.

〔Example〕

 Specifically, the printing plate is prepared by the following method.

First, a coating composition (1) is formed on a cover film (2).
And left for about 15 minutes to evaporate the solvent in the coating composition (1) to form a coating composition layer (1 ′) (first)
Figure). Next, the cover film (2) is overlaid on the photosensitive resin layer (4) with the coating composition layer (1 ') facing down, and a positive film (3) [e.g. , And the below-mentioned ultraviolet rays pass through the white portion. And irradiating with ultraviolet (r) to cure the ultraviolet (r) irradiated portion of the photosensitive resin layer (4) (FIG. 2).
Thereafter, the positive film (3) and the cover film (2) are peeled off, and the coating composition layer (1 ') and the photosensitive resin layer (4) of the unexposed portion (b) serving as an image portion are washed out and dried for several hours. As a result, intaglio printing plates (A) and (A ') are prepared in which only the exposed portions (a) which become non-image portions are surface-treated (FIG. 3).

The thickness of the photosensitive resin layer (4) does not significantly affect the effects of the present invention. However, due to the nature of intaglio printing, the image should have a depth of about 100 μm. 0.1mm to 1mm for practical use
A moderate thickness is easy to use.

As the coating composition (1), when irradiated with ultraviolet light (r), the photosensitive resin layer (4) must be cured by passing through the coating composition layer (1 '). It is necessary to use something excellent.

(A) In one of the objects of the present invention, in the intaglio printing plate surface without wiping and the plate making method, a liquid photosensitive resin commercially available for letterpress printing can be used as the material of the plate surface.

The liquid photosensitive resin preferably has a hardness of about 40 ° (Shore A) to about 80 ° (Shore D) as measured by a rubber hardness meter during curing. If the hardness is less than 40 ° (Shore A), the strength of the plate surface is remarkably reduced because it is too soft.
When the pressure is higher than (Shore D), the required printing pressure increases, so that the surface silicone layer is easily damaged and the printing durability of the plate surface is reduced.

Naturally, ink repellency is required, and a uniform thin film must be formed on the cover film (2). As a coating composition (1) suitable for such a purpose, a commercially available condensed RTV
Silicone rubber solutions can be used. The appropriate thickness of the silicone rubber is about 1 to 5 μm. If a commercially available solution is used as it is, the film thickness becomes large. Therefore, when it is actually used, it is used after being diluted with a solvent such as n-heptane.

The silicone rubber is exposed in an uncured state by overlapping with the liquid photosensitive resin layer (4), and then left for several hours to cure the silicone rubber, thereby eliminating the pretreatment agent generally called a primer. Even photosensitive resin layer (4)
Good adhesiveness with the resin.

Regarding development, the coating composition layer (1 ') of the exposed portion (a) which becomes a non-image portion when the cover film (2) is peeled off
The silicone rubber is transferred to the surface, but the silicone rubber is not transferred to the unexposed portion (b), which is an image area, and the photosensitive resin layer (4) remains in a liquid state. it can.

The developing solution does not require a special solvent, and can be sufficiently washed out with a developing solution of a liquid photosensitive resin.

Cover film coated with silicone rubber liquid (2)
Is required to have excellent UV transmittance, and commercially available PET (polyethylene terephthalate) film, TAC
(Triacetate cellulose) film, fluorine film and the like can be used. When a thick cover film (2) is used, the resolution is reduced. Therefore, it is better to be as thin as possible. However, when it is too thin, the workability is deteriorated.
About the thickness is good.

The printing ink must of course be an intaglio ink that does not adhere to the silicone rubber. A measure of the adhesion between ink and silicone rubber is the tack value of the ink. If the tack value is high, it is relatively difficult to adhere to the silicone rubber and the background is hardly stained. On the contrary, if the tack value is low, the reproducibility of the image becomes poor. A suitable tack value is about 9 to 15 (30 ° C.).

(B) The coating composition (1) for improving the durability of the intaglio printing plate for simultaneous front and back printing, which is another object of the present invention, and the coating composition layer (1 ') are generally hard. A UV-curable polyfunctional acrylic resin called a coating agent is most suitable.

The adhesion between the hard coat agent and the photosensitive resin layer (4) is good, and a pretreatment agent called a primer is not particularly required.

As the plate surface material to be used, a liquid photosensitive resin or a solid photosensitive resin plate commercially available for letterpress printing can be used. Regarding hardness, shear D30 ° at the time of curing
~ 70 ° can be used.

The cover film (2) to which the hard coat agent is applied
It is necessary to have excellent ultraviolet (r) transmittance.
The same film as above can be used.

As the printing ink, a normal intaglio ink can be used. When printing is performed with the same pattern and the same ink, a good printed matter can be easily obtained on the elastic plate surface as compared with the metal plate surface.

Wiping may be performed in the same manner as in intaglio printing, that is, in any of methods such as hand brushing, paper brushing, and roller brushing.

Here, it is sufficient that the printing pressure of both (a) and (b) is considerably lower than that of the metal plate surface. 150k on metal plate
Even when g / cm is an appropriate printing pressure, a printed matter having a printing pressure of 100 kg / cm or less can be obtained by using an elastic plate. The appropriate printing pressure varies depending on the pattern, the properties of the paper, and the like, in addition to the hardness of the plate surface. Generally, the lower the plate surface hardness, the lower the printing pressure becomes appropriate.

There is no special condition for the printing paper, and any paper can be used as long as it can be used for ordinary intaglio printing.

Example of (a) A hand-drawn line drawing is reduced and photographed to make a negative film. From this negative film, a line drawing positive film (3) is produced by contact exposure. As the film, a lith film (for example, Fuji Ortho Lith Film VO-100II) is used.

Condensed RTV silicone rubber solution (PRX-305 manufactured by Toray) on a cover film (made by Lumirror Toray) with a thickness of 50 μm
A solution diluted 3 times with heptane is applied to a thickness of 5 μm with a knife coater, dried at room temperature for 15 minutes to evaporate the solvent.

Film (5) as a support made of a photosensitive resin for liquid letterpress (Tevista A, Shore A hardness of 40 ° manufactured by Tokyo Ohka Kogyo Co., Ltd.)
An appropriate amount of the film is flowed on [Fivisa Film Base M-30, manufactured by Tokyo Ohka Kogyo Co., Ltd.], and the above cover film (2) is brought into close contact with the silicone rubber coated side down, and the thickness is reduced to 1 mm with a knife coater. Furthermore, a line drawing positive film (3) is overlaid thereon, and exposed for 1 minute with a chemical lamp. After exposure, the positive film (3) and the cover film (2) are peeled off, the unexposed portion (b) is washed out, and the silicone rubber on the exposed portion (a) is left at room temperature for half a day to become a non-image portion. Is cured to form an intaglio plate surface (A).

This intaglio printing plate (A) has an image width of 300 μm and a depth of 100 μm
Degree version was obtained. When a printing experiment was carried out on the intaglio plate surface (A), no ink adhered to the non-image portion, and good image reproducibility was obtained without wiping, which was the same as a normal intaglio plate surface.

 The printing conditions are as follows.

Printing ink Intaglio ink (tack value 15) Printing paper Banknote paper Printing speed 1m / s Printing pressure 100kg / cm YE-3085 (made by Toshiba Silicone), KE-42-TS (made by Shin-Etsu Silicone) as condensation type RTV silicone rubber , ARFPP-70 (Shore D hardness 80 manufactured by Asahi Kasei Corporation) as a photosensitive resin
°), Tevista PW-210 (Shore D, manufactured by Tokyo Ohka Kogyo Co., Ltd.)
Similar results were obtained when using a hardness of 40 °).

Example of (b) A 50 μm thick cover film (2) [Lumirror Toray Co., Ltd.] was coated with an ultraviolet-curable hard coat agent (9H Hard Coat, 3Like Corporation) as a coating composition (1 ') using a knife coater. Apply to a thickness of 5 μm and dry at room temperature for 15 minutes.

This cover film (2) is coated with a photosensitive resin plate for letterpress (4 ') [Shore D hardness manufactured by Toray Relief WF 95 BS Toray.
30 °], the surface coated with the hard coat agent is adhered downward, and the positive film (3) of the line drawing used in the above example (a) is overlaid thereon, and exposed with a chemical lamp for 1 minute. After the exposure, the positive film (3) and the cover film (2) are peeled off, and the unexposed portion (b) is washed out to form an intaglio plate surface (A '). This intaglio printing plate (A ') has an image width of 30
A plate having a depth of about 100 μm and a thickness of 0 μm was obtained.

A printing experiment was performed to compare the printing durability between the intaglio printing plate (A ') and the printing plate that had not been treated with a hard coating agent. However, the processed image showed good image reproducibility of fine image lines even after printing 5,000 sheets. The printing conditions are as follows.

Printing ink Intaglio printing ink Printing paper Fine paper Wiping method Roller wiping with PVC roller Printing speed 0.25m / s Printing pressure 120kg / cm Printing experiments using these intaglio printing surfaces (A ') under the same printing conditions as in (a) The image reproducibility was the same as that without the hard coat agent treatment, and the image shape was also changed to the untreated one by measurement with a three-dimensional roughness measuring device (SE-3AK manufactured by Kosaka Laboratories). I knew it wasn't.

In order to compare the abrasion resistance of the intaglio printing plate (A ') with the printing plate not treated with the hard coating agent, a non-image portion was subjected to a wear test using a Taber type abrasion tester. The test conditions are as follows.

Abrasion wheel CS-17 Load 500g Abrasion test was performed under the condition of 500 rotations or more.The untreated one showed a wear amount of 3.9mg, but the surface treated one had 1.3mg.
And improved wear resistance.

As a photosensitive resin plate (4 '), Tevista PW-210
(Shore D hardness 40 °, manufactured by Tokyo Ohka Kogyo Co., Ltd.)
WF 95 CH (Shore D hardness 70 °, manufactured by Toray), BC-920 (manufactured by Toyobo), KKS-1160 (manufactured by Nippon Synthetic Chemical Industry) as a hard coating agent, and Fujitack (manufactured by Fuji Film, 50 μm thick) as a cover film (2) ) Gave similar results.

[Effects of the Invention] According to the intaglio printing plate surface and the plate making method of the present invention, the wiping step when performing intaglio printing on banknotes, securities, and the like is eliminated, and the time required for plate printing is reduced. In addition, there are excellent effects such as a reduction in the amount of ink used and an improvement in working efficiency.

It also improves the abrasion resistance of the printing plate when performing simultaneous intaglio printing on banknotes and securities, etc., and reduces the cost and improves work efficiency by extending the life of the printing plate. Has an excellent effect. In this case, of course, the present invention can be used not only for simultaneous printing on both sides but also for intaglio printing on only one side.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic sectional view when a coating composition layer (silicone rubber layer or hard coat layer) is formed on a cover film. FIG. 2 is an enlarged schematic cross-sectional view when a cover film coated with a coating composition is overlaid on a photosensitive resin layer, and a line drawing positive film is overlaid and exposed. FIG. 3 is an enlarged schematic cross-sectional view of an intaglio plate surface prepared by washing out a coating composition layer and a photosensitive resin layer in an unexposed portion after exposure. (A) (A ') ... intaglio printing plate, (1) ... coating composition, (1') ... coating composition layer, (2) ... cover film, (3) ... positive film, (4) ... photosensitive resin layer, (4 ') ... photosensitive resin plate, (5) ... support,
(R) UV light, (a) exposed part, (b) unexposed part.

Claims (6)

(57) [Claims] 1. A photosensitive printing plate comprising a photosensitive resin layer (4) having a plastic film or a metal plate as a support (5), a coating composition layer (1 ') and a cover film (2) is exposed. Thereafter, the coating composition layer (1 ') and the photosensitive resin layer (4) in the unexposed portion are removed so as to form a recess holding the ink, so that the coating composition is formed only on the surface of the non-image area. An intaglio printing plate characterized by forming a layer (1 '). 2. A photosensitive printing original plate comprising a photosensitive resin layer (4) using a plastic film or a metal plate as a support (5), a coating composition layer (1 '), and a cover film (2) is exposed. Thereafter, the coating composition layer (1 ') and the photosensitive resin layer (4) in the unexposed portion are removed so as to form a depression holding the ink, so that the coating composition is formed only on the surface of the non-image area. A method for making an intaglio printing plate, comprising forming a layer (1 '). 3. The intaglio printing plate according to claim 1, wherein RTV silicone rubber is used as the coating composition layer (1 '). 4. The method according to claim 2, wherein RTV silicone rubber is used as the coating composition layer (1 '). 5. The intaglio printing plate according to claim 1, wherein a UV-curable polyfunctional acrylic hard coat agent is used as the coating composition layer (1 '). 6. The method according to claim 2, wherein a UV-curable polyfunctional acrylic hard coat agent is used as the coating composition layer (1 ').