JPS58214157A - Method for forming reticulate projection on base film - Google Patents

Abstract

PURPOSE:To avoid a waving phenomenon of a base film, by providing a recessed suction/adhering path to a transparent mesh point picture carrier forming a minute mesh point projection at a non-picture part. CONSTITUTION:The photosensitive resin is adhered on a base film, and a pattern to be turned into picture lines is exposed from the resin side. At the same time, a pattern to be turned into a projection which prevents the contamination of background is exposed from the base side. For a hard tansparent mesh point picture carrier 23 of said projection, the fringe part 24a of a transparent plate matter 24 is set at the same level as many projections 24b. The rest part is formed into a recess part 24c. A tip edge 24b' and the part 24a have a face contact with the base film, and the part 24c is totally connected to an suction hole 24d and then to a vacuum pump to suck and adhere the film. Thus a waving phenomenon can be avoided for the film. The edge 24b' is transparent, and the part 24c has a processed surface 25 of 0-50% light transmissivity through metallic plating or painting.

Description

DETAILED DESCRIPTION OF THE INVENTION In the process of producing a printing plate using a photosensitive resin, the present invention provides a base film with dot-like protrusions on the base film to prevent staining of non-image areas during printing. The present invention relates to a method for forming wavy trenches without causing them.

Various methods have been used to create letterpress printing plates since ancient times, such as casting with lead alloys, corrosion of metal plates, and in recent years using photosensitive resin, but when printing, ink reaches the non-image areas. A high relief was required to prevent layering and scumming. On the other hand, however, in the case of rotary printing, etc., plates with high reliefs, that is, thick plates, are inconvenient to mount on the plate cylinder of a rotary printing press, and from the viewpoint of ease of installation and cost, it is difficult to A thinner plate was desired.

Therefore, several years ago, the present applicant researched a plate with a relatively low relief that could be printed without scuffing using a conventional letterpress printing machine without the need for a special printing machine, and a method for making the same. Disclosed (Japanese Unexamined Patent Publication No. 51-115102, No. 51-1)
No. 27804, No. 52-32702). The outline is
A photosensitive resin is placed in close contact with a base film that is transparent or translucent to actinic rays, and the actinic rays are irradiated from the photosensitive resin side through the entire transparent image carrier, and at the same time, the active rays are irradiated from the base film side through the transparent halftone image object. emits a ray of light,
This is a method of forming minute dot-like protrusions on the base film in relief corresponding to the image area and in the non-image area, and the area ratio of the transparent halftone area of the transparent halftone image carrier used in this case is For example, the size is 1 to 40 cm, and thus a minute dot-like projection 1 is formed on the non-printing area of the plate.For example, the area of the top is 0.4 m.
m2 or more 1 height 0.01mm or more 2 pieces 20L~4,
0004 town-2 is obtained. An example of the conventional method for forming the above-mentioned dot-like protrusions will be further explained with reference to the drawings. Fig. 1 is an overall explanatory diagram of the exposure process, Fig. 2 is an enlarged explanatory diagram showing the main parts of the exposure device in Fig. 1, and Fig. 6 is an enlarged explanatory diagram showing a part of an example of the obtained second plate. It is a diagram. As shown in FIG. 1, a transparent cover film 1 is intermittently fed and moved by a cover film supply roll 2.

When a predetermined portion of the cover film 1 reaches the horizontal surface plate 3, the haggett 4 installed above it is turned over and the photosensitive resin 5 stored in C is transferred to the cover film 10.
Then, a transparent or translucent base film 7 is supplied by a laminating roll B and laminated on the photosensitive resin 5 applied to the cover film 1, and its thickness is to make it even more uniform. When the thus obtained laminate 9 is further moved and stopped at a predetermined position, the close contact roll 8 improves the close contact between the transparent image carrier 14 and the cover film 1. Next is the laminate? The transparent halftone image carrier 11 and the upper glass 15 are lowered onto the top, and then the halftone image exposure device 10 irradiates actinic light from the light source 12 through the transparent halftone image carrier 11 from the base film Z side to form the halftone dot image carrier 11 and the upper glass 15. The cover film 1 is subjected to halftone image exposure to form dot-like protrusions, and the cover film 1 is passed through the transparent image carrier 14 by the relief exposure device 13.
Relief exposure is done from the side. After the exposure is completed, the laminate 9 is further moved, the cover film 1 is peeled off by a peeling roll 17, the remaining uncured photosensitive resin is scraped off by a blade 18, and then the cover film 1 is wound onto a cover film take-up roll 19.

The laminate 9 of the base film 7 from which the film 1 has been peeled off and the photosensitive resin 5 that has been photocured is transferred to the conveyor 2.
0, and then put into the next process of washing, drying, and finishing, where the residual uncured photosensitive resin is removed by alkaline washing and water washing, followed by draining, surface treatment, and drying. , further post-exposure to completely harden the relief, and the sixth
Obtain a plate as shown in the figure. In FIG. 6, 21 is a dot-like projection (also called a back highlight), 22a is a relief, and its standard dimensions are j the thickness of the base film 7 0.
．． 10 mIn, height of relief 22 0.40 mm, height of hack ha illite 0.05 mm, total thickness 0°5 [
It is 1 mm.

By making such a large number of minute dot-like protrusions 21 exist in the non-printing area between the reliefs 22, the height can be reduced to 0.
- Despite the relatively shallow relief 22 of 40 nm, the printing IT is prevented from coming into contact with the base film 7 in the non-image area, and no stains occur.

By the way, in the exposure process described above, conventionally thin films (negative films) are used as both the transparent halftone image carrier 11 and the transparent image carrier 14, and the upper glass 15 is used for each of the transparent halftone image carriers 11 and 14.
I have been using it by pasting it on the lower glass 16. When the 84 bodies 9 are exposed through the transparent halftone image carrier 11 of such a halftone image exposure device 10, polymerization of the photosensitive resin 5 is started and reaction heat is generated. When produced, the reaction heat cannot escape and the upper glass plate 15 rises, and the base film 7 adjacent to it rises to a height of 7. Since there is some gap in the second
As shown in the figure, the waving phenomenon (also referred to as zebra phenomenon) in the base film 7 is particularly likely to occur in the case of a large-sized version. Printing plates produced by exposure with such waving phenomena may be unstable when mounted on a printing press, or the top surface of the relief of the printing plate may be too high. Good printing could not be achieved due to uneven printing and distorted lines. In order to prevent such a waving phenomenon from occurring, it is impossible to bring the base film 7 into close contact with the upper glass 15 by suction because the film-like transparent halftone image carrier 11 is interposed. Ta. In order to reduce the waving phenomenon of the base film 7 as much as possible, cooling equipment such as a cooler for cooling the base film 7 is required, but even then, the waving phenomenon cannot be completely prevented. Furthermore, the film-like transparent halftone image carrier 11 is weak and not durable, requiring frequent replacement.As mentioned above, the conventional method for forming halftone projections has drawbacks that need improvement. Ta.

The present inventor conducted research with the aim of providing a method for forming dot-like protrusions without the above-mentioned defects in the process of producing a printing plate using a photosensitive resin, and found that, unlike the transparent image carrier 14, The transparent halftone dot image carrier 11, which may always have the same halftone dot image, is preferably a thick hard carrier from the viewpoint of durability; The present invention was completed after discovering that the base film 7 can be brought into close contact with suction by making the recesses communicate with each other and creating a negative pressure.

That is, in the present invention, photosensitive resin scraps are closely placed on a base film that is transparent or translucent to actinic rays, and actinic rays are irradiated from the base film side through a transparent halftone image carrier to coat the base film. When forming a large number of minute dot-like protrusions, the tips of the many minute protrusions that come into surface contact with the base film as the transparent halftone image carrier are made transparent, and the other portions are concave portions with an actinic light transmittance of 0 to 50. The present invention relates to a method for forming projections in the form of halftone dots on a base film, characterized in that a hard transparent halftone dot image carrier having a suction passage of 30 mm is used, and the base film is brought into close contact with the base film by suction.

The present invention will be explained in detail below with reference to the drawings, which illustrate one embodiment of the method of the present invention.

Figure 4 shows hard transparent halftone dot image 1 used in the method of the present invention.
FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4, FIG. 6 is a partially enlarged cross-sectional view of section B in FIG. 5, and FIG. It is a partially enlarged sectional explanatory view of another example of the part corresponding to.

Rigid transparent halftone image carrier 26 used in the method of the invention
An example of this is shown in Figures 4 to 6, for the first time! The peripheral edge 24a of the transparent plate-like body 24 and a large number of minute projections 24b
The other parts are four parts 24c with the same height. The tip 24b' of the protrusion 24b is located at the same location as the peripheral edge 24a, and both of them are in surface contact with the base film 7. All the recesses 24c are in communication with each other and the suction hole 2
It is connected to 4d. It is sufficient that the suction hole 24d is provided in at least one place, and passes through the front and back sides of the hard transparent plate-like body 24, and is connected to a vacuum pump by a vibrator, a hose, or the like.

The suction groove 240' provided inside a part or the entire circumference of the peripheral edge portion 24a helps to smoothly perform suction, but may be omitted. In terms of dimensions, d, the depth of the bulky recess 24c of the protrusion 24b)': L ~ 500μ.

Pitch 100~1.000μ, diameter of tip 24b' 50~
600μφ is standard. As the hard transparent plate-like body 24, a material having good actinic ray transmittance, such as glass or hard plastic, is used. The sharp end 24b' of the protrusion 24b is left transparent, and the other parts, that is, the vicinity of the peripheral wall of the protrusion 24b,
Surfaces such as the surface of the recess 24c are processed to have an active light transmittance of 0.
The processing section 25 is 50 inches long.

This processing involves metal plating (electroplating, chemical plating).

The degree of actinic light transmittance is adjusted by the plating, the thickness of the coating, etc. This processed part 25 has a live light transmittance of 0~
50qI) is sufficient because the active light transmittance is 0%.
In other words, if it is completely opaque, only halftone projections will be formed at predetermined positions, but if the actinic ray transmittance is 50% or less, the photoreceptor resin 5 on the base film Z side will harden and relief exposure will occur. This is because it is well integrated with the photosensitive resin 5 and the strength of the plate is improved.

An example of a method for manufacturing such a hard transparent halftone dot image 1 carrier 26 will be described below. First, for example, a photosensitive resin is applied or coated on a glass plate, a halftone negative film is placed on top of the film, and actinic light is irradiated to expose the photosensitive resin in the halftone dots and cause a reaction.

Next, when the unreacted photosensitive resin other than the halftone dots is washed away with a solvent or the like, the glass parts other than the halftone dots are exposed.

Thereafter, the glass portion other than the ε halftone dots is dissolved and removed from the surface by etching with butic acid or the like, thereby forming a recessed portion.

Next, chromium plating, for example, is applied to the recessed portion by vapor deposition to form a processed surface having a predetermined active light #, 1 incidence, which is adjusted depending on the thickness. Thereafter, the photosensitive resin cured in the halftone dot area is removed, and suction holes, suction grooves, etc. are processed.

A hard transparent halftone image carrier 23 is thus obtained.

The materials used in the method of the present invention other than those mentioned above are the same as those described in the above-mentioned publications. 2. A photosensitive resin 5 is a material whose solubility in various solvents is significantly reduced by irradiation with actinic rays compared to before photocuring or irradiation. Examples of such resin compositions include those containing a compound having an addition-polymerizable unsaturated group as a main ingredient and a photopolymerization initiator added thereto.

Examples of compounds having an addition-polymerizable unsaturated group include acrylic acid, methacrylic acid, or esters thereof, such as alkyl, cycloalkyl, tetrahydrofurfuryl, allyl, grindyl, hydroxyalkyl acrylates and methacrylates, alkylene glycols, and polyesters. Oxyalkylene glycol mono(d) diacrylate and methacrylate, or trimethylolpropane triacrylate and methacrylate, pentaerythritol tetraacrylate and methacrylate, acrylamide, methacrylamide, or derivatives thereof.

For example, N-methylolacrylamide and methacrylamide, N-N'-alkylenebisacrylamide and methacrylamide, diacetone acrylamide and methacrylamide, etc., and styrene.

Vinyltoluene, divinylbenzene, diallyl phthalate, triallyl sialate, vinyl acetate.

Addition polymerizable unsaturated monomers such as acrylonitrile.

unsaturated oropolyester and alkyd resins, unsaturated polyurethane resins such as hydroxyalkyl acrylates,
Examples include polyurethane resins modified with addition-polymerizable unsaturated monomers having active water ice, such as carbonate or methacrylate.

Examples of photopolymerization initiators include verezoin, benzoin alkyl ester, α-, methylbenzoin and hyalkyl ether, α-phenylbenzoin, α-allylbenzoin, anotraquinone, chloroa/traquinone, methylanthraquinone, ethylanthraquinone, benzyl, diacetyl, acetophenone. , ω-bromoacetophenone, α
Examples include -naphthalenesulfonylchloride F, diphenyl disulfide, dyes 1 such as eosin, thionin, etc.

The photosensitive resin composition is a composition in which one or more of the above-described addition-polymerizable unsaturated group-containing compounds and a photopolymerization initiator are added. Furthermore, if necessary, a polymerization inhibitor, such as hydroquinone, p-methoxy7phenol, catechol, tert-7'f-hydroquinone,
Benzoquinone, p-phenylenediamine, picric acid,
Phenothiazine etc. are added.

Other polymer compounds soluble in water or alkaline aqueous solution,
For example, a polymer compound such as polyvinyl alcohol, a polyvinyl alcohol rust conductor, a cellulose rust conductor, polyacrylic acid, polymethacrylic acid, polyacrylamide, or alcohol-soluble polyamide, the addition polymerizable unsaturated compound and a photopolymerization initiator, and if necessary Examples include a composition to which a thermal polymerization inhibitor is added depending on the composition, and a composition comprising polyrayene, polythiol, and a photosensitizer as shown in Japanese Patent Publication No. 46-29525.

In the method of the present invention, as shown in FIG. Glass plate 1
5 and a hard transparent halftone image carrier 23 instead of the transparent halftone image carrier 11, and the laminate 90 base film 7 surface stopped at the exposure position of the halftone image exposure device 10 is placed in a vacuum pump connected to a vacuum pump. By suctioning and adhering to the concave portions 24c of the transparent halftone image carrier 23, the base film 7 does not cause any waviness even under high temperatures and forms a clean flat surface even in the case of large printing plates. The peripheral edge 24a of the transparent halftone image phase body 23 and the tip 24b of the protrusion 24b
′ comes into surface contact. By performing halftone image exposure and relief exposure in such a state, a flat printing plate can be obtained.

Therefore, the method of the present invention can be carried out not only when using a liquid photosensitive resin as described above, but also when using a solid photosensitive resin. Further, since the hard transparent halftone image carrier 26 is hard and highly durable, there is no need to replace it over a long period of time. Furthermore, no cooler equipment is required to cool the area around the upper glass 15.

The method of the present invention, which has the above-mentioned effects,
This is a device that allows printing plates to be manufactured in large size, at high speed, and in a good manner, and is valuable for improving printing technology.

[Brief explanation of the drawing]

Fig. 1 is an explanatory view of the metal body in the exposure process of the conventional method for forming halftone protrusions, Fig. 2 is an enlarged explanatory view showing the main parts of the exposure device in Fig. 1, and Fig. 6 is an illustration of the obtained plate. FIG. 4 is a clear view of one example of a hard transparent halftone image carrier used in the method of the present invention; FIG. 6 is a partially enlarged sectional view of part B in FIG. 5; FIG. 7 is a partially enlarged cross-sectional explanatory view of another embodiment of the portion shown in FIG. 6. 1.Cover film 2.Cover film supply roller 6..Surface plate 4..Packet 5..Photosensitive resin 6..Laminating roll 7..Base film 8@Sachi adhesion roll? Laminate 10 Halftone image exposure device 11 Transparent halftone image carrier 12 Light source 16 Relief exposure device 14 Transparent image carrier 15 Upper glass 16 Lower glass 17 Peeling Roll 18... Blade 19... Cover film winding roll 20... Carrying out conveyor 21... Halftone projection 22... Relief 26... Hard transparent halftone image carrier 24... Hard transparent plate-like body 24a... Peripheral portion 24b... Protrusion 24b'... Protrusion tip 24c... Recess 24C'... Suction groove 24d Suction hole 25... Machining surface \, 4.2-, Papa;, -1, ``・ツ'

Claims (1)

[Claims] 1. A photosensitive resin layer is closely placed on a base film that is transparent or translucent to actinic light, and actinic light is irradiated onto the mousse film through a transparent halftone image carrier from the base film side. When forming a large number of minute dot-like protrusions, the tips of the many minute protrusions that are in surface contact with the base film as the transparent halftone image carrier are made transparent, and the other parts are recessed portions with active light transmittance of 0 to 50 inches. 1. A method for forming dot-like protrusions on a base film, which comprises using a hard transparent dot image carrier having a suction passageway and bringing the base film into close contact with the base film by suction.