JPH09274310A - Method for joining flexographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the joining strength by a simple and inexpensive method without decreasing the printing characteristics by treating the end face of each printing plate with monomers having (meth)acryl groups in the molecule, injecting a liquid photosetting resin into the space between the end faces and irradiating the resin with UV rays. SOLUTION: An adhesive tape 2 such as a cellophane tape is adhered to the lower face all over the length of a groove 15 formed between printing plates 1 disposed facing to each other. A cyanoacrylate is applied on the surface of each joining face 13 to wet the surface. Then a liquid photosensitive resin (source liquid) 30 is supplied to fill the groove 15. An adhesive tape 20 is adhered on the upper face along the groove filled with the source liquid 30. The printing plates 1 connected to each other with the adhesive tapes 2, 20 are mounted on an exposure device equipped with a UV lamp and the groove filled with the source liquid 30 is exposed through the upper and lower tapes. After the liquid 30 is hardened, the adhesive tapes 2, 20 are peeled to obtain a printing plate having a smooth printing surface 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a large flexographic printing plate by connecting a plurality of printing plates produced using a photocurable resin.

[0002]

2. Description of the Related Art A printing method using a relief printing plate such as a rubber plate or a rubber plate, which is excellent in softness and elasticity, is generally called flexographic printing, and is used for cardboard printing, heavy bags, beverage containers, films, seal labels, etc. It is used in the printing field. Recently, since printed materials with fine and complicated patterns are increasing, a photosensitive resin plate using a photoengraving technique is often used. As the photosensitive resin plate used for such a photosensitive resin printing plate, there are a liquid type and a solid type at room temperature, but after the plate-making process, both become a solid printing plate and have characteristics as a printing plate. There is not much difference in usage. In printing applications such as corrugated cardboard packaging materials in which these photosensitive resin printing plates are used, larger printing plates are required from the pursuit of large-sized electric products and ultimate printing productivity, and Japanese Patent Publication No. 3-7484. Tokuhei 6-29965
There is known a method for producing a large printing plate in which a plurality of plates are connected, as described in Japanese Patent Publication No.

[0003]

The strength of the joint portion of the photosensitive resin printing plate, which is enlarged in size by joining and connecting a plurality of plates, does not meet the stress in normal printing after being set on the printing cylinder. Although no particular problems occur, particularly when the printing plate is large, it is likely to be subjected to severe stress such as handling, and careful attention has been paid in handling the printing plate until it is set on the printing cylinder. However, despite such precautions, sometimes the joint could not be endured due to the stress of handling when the printing plate was stuck, and the joint part was destroyed, and the delivery time could not be met due to reprinting. Because of this, there was a problem that it would be costly.

Further, as the joint portion of the printing plate, generally, a portion having a large area of the joint surface is generally used, and the joint portion is often the printing surface. In this case, if the material of the joint is too hard compared to the hardness of the printing plate,
The joint portion may appear on the printing surface and impair the print quality. Therefore, it is desirable to form the joint with a photosensitive resin having the same printing characteristics as the printing plate, but in this case, there is a problem that it is difficult to use a general adhesive. As the material constituting the joint after joining, the wettability with respect to the printing plate and the printing ink does not significantly change, and,
The hardness thereof is preferably the same as or lower than that of the printing plate, and is preferably 20 ° or less than the hardness of the printing plate in view of printing characteristics. Further, the constituent materials thereof are required to have printing ink resistance and plate detergent resistance, and there are no well-balanced materials such as adhesives that are commonly used are too hard, repel ink, or lack ink resistance.

[0005]

As a result of earnest studies on a method of increasing the strength of the joint portion of the printing plate, the present inventors have made a great effort to improve the joint strength by a very simple and inexpensive method without impairing the printing characteristics. The present invention has been completed and the present invention has been completed. That is, the first aspect of the present invention is to abut the adjacent end faces of a plurality of photocurable resin printing plates, and treat the end faces of the respective abutting printing plates with a monomer having a (meth) acrylic group in the molecule. Then, a liquid photocurable resin is injected into a gap formed between the end faces, and then ultraviolet irradiation is performed, which is a plate connecting method for a flexographic printing plate.

In the second aspect of the present invention, adjacent end faces of a plurality of photocurable resin printing plates are butted, and each of the butted end faces of the printing plate is treated with a monomer having a cyanoacryl group in the molecule. Then, a liquid photocurable resin is injected into a gap formed between the end faces, and then ultraviolet irradiation is performed, which is a method for connecting flexographic printing plates. By adopting these methods, the printing performance of the joint portion does not become a problem in printing, and the strength of the joint portion of the printing plate can be dramatically improved.

(Operation) The position of the pair of printing plates facing each other at their joint surfaces and abutting each other is fixed by the adhesive tape attached to both lower surfaces. A plate binder monomer [a monomer having a (meth) acrylic group or a cyanoacryl group in the molecule] is applied to the surfaces of the bonding surfaces, and then a liquid photosensitive resin liquid for plate binder is poured. After that, by sticking the adhesive tape on the upper surface of both printing plates along the poured photosensitive resin liquid filling part, the surplus photosensitive resin for plate stencil partially raised on the upper surfaces of both printing plates is Drained from. As a result, the surface of the photosensitive resin for plate connection becomes a smooth surface that substantially matches the surfaces of both printing plates.

The filled photosensitive resin for plate tie is cured by an ultraviolet lamp together with a monomer having a (meth) acryl group or a cyanoacryl group in the molecule, and joins both printing plates as a connecting portion having the same property as the printing plate. It is firmly adhered to the surface. Finally, the pressure-sensitive adhesive tape is peeled off to obtain a smooth printing plate surface without unevenness at the joint. Examples of the monomer having a (meth) acrylic group in the molecule used in the present invention include acrylic acid esters having a (meth) acrylic group in the molecule, and these have improved adhesiveness, coating property and stability. To this end, a polymerization initiator, a stabilizer, a thickener, a plasticizer and the like can be added. In addition, as a monomer having a (meth) acrylic group in a molecule, a medium molecular weight polymer generally called an oligomer and having a molecular weight of up to about 10,000 is also included, and examples thereof include alkyl such as ethyl, butyl, and 2-ethylhexyl. (Meth) acrylate, epoxy (meth) acrylate, for example, bisphenol A diglycidyl ether reacted with (meth) acrylic acid, polyester (meth) acrylate, for example, adipic acid / ethylene glycol oligomer (meth) acrylic acid Reacted with, polyether (meth) acrylate such as polypropylene oxide reacted with (meth) acrylic acid, urethane (meth) acrylate, for example, urethane oligomer having a terminal hydroxyl group reacted with (meth) acrylic acid Things, diene Gomer (meth) acrylates, for example, carboxyl-terminated 1,2-butadiene oligomers reacted with glycidyl (meth) acrylate, and silicon (meth) acrylates, for example, polysilanols reacted with (meth) acrylic acid are included. .

As the monomer having a cyanoacrylic group in the molecule used in the present invention, for example, 2-cyanoacrylic acid ester can be used, and specifically,
Methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, sec-butyl, amyl, n-hexyl, cyclohexyl, heptyl, n-octyl, 2-ethylhexyl, dodecyl, allyl, Examples thereof include 2-cyanoacrylates such as propargyl, benzyl, phenyl, methyl cellocerve, ethyl cellocerve, 2-chloroethyl, hexafluoroisopropyl and trifluoroethyl.

In the case of a monomer having a cyanoacryl group in the molecule, curing proceeds even before curing with an ultraviolet lamp. Therefore, in the case of plate connection of a large plate, partial temporary fixing using a portion other than the print image surface is used. Can be done at the same time,
It is easy to use.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the present invention will be described below based on Examples.

[0012]

Example 1 A printing plate to be joined with a plate thickness of 7 mm for corrugated board made by using liquid photosensitive resin APR F-47 (made by Asahi Kasei Kogyo KK, for corrugated board printing plate) is shown in FIG. Show. The pair of printing plates 1 and 1 to be joined are each composed of a strip-shaped relief portion 10, a shelf portion 11 and a base portion 12. The plate connecting method of the present invention is one in which a photosensitive resin is injected and filled between the bonding surfaces 13, 13 of a pair of printing plates to be bonded, and then the photosensitive resin is cured by irradiation with ultraviolet rays and bonded. is there.

The concrete procedure of the plate connecting method according to the present invention is as shown in FIG. 2A, in which the joint surfaces 13, 13 are arranged so as to face each other with a slight gap (for example, about 1 mm), An adhesive tape 2 such as cellophane tape was attached to the lower surface over the entire length of the groove 15 formed between the two printing plates 1 and 1. Next, as shown in FIG. 2B, cyanoacrylate (trade name: Bond Aron Alpha / Instant for general use, manufacturer: Toagosei Kagaku Co., Ltd.) was applied to the surfaces of the bonding surfaces 13, 13 so that the surfaces wet each other. After waiting for about 30 seconds after coating, the liquid photosensitive resin AP having the same or slightly larger amount as the capacity of the groove 15 is provided in the groove 15 as shown in FIG. 2C.
RF-47 (made by Asahi Kasei Corporation, for corrugated board printing plate) 30 was filled. Then, as shown in FIG.
The adhesive tape 20 was attached to the upper surface along the filled portion of 0.
The UV lamp shown in FIG. 2E (TOSHIBA FLR20S-BL
/ MA) attached to the exposure device, the single-sided adhesive tape 2,
The printing plates 1 and 1 connected to each other by 20 were attached, and the filled portion of the stock solution 30 was exposed from above and below for 5 minutes. After the stock solution 30 was cured, the adhesive tapes 2 and 20 were peeled off to obtain a printing plate having a smooth printing surface 14 as shown in FIG. 2F.

In order to measure the adhesive strength of the joint, a strip was cut into a strip having a width of 1 cm in a direction orthogonal to the joined portion, and the strength of the joint was measured by a tensile tester. The fracture toughness of the joint surface is 66.0.
% ・ Kg / cm2 (= breaking strength [Kg / cm2] × elongation at break [%]), which was extremely high, and the breaking did not remain at the joint, so it was confirmed that the joint strength was good. .

[0015]

Example 2 Photosensitive resin printing plate (trade name: APR F-91 for corrugated board printing plate, manufacturer: Asahi Kasei Corporation)
Printing plates were connected in the same manner as in Example 1 using a plate hardness Shore A of 40 °. At this time, instead of cyanoacrylate, ethyl cyanoacrylate (trade name: Loctite 406, manufacturer: Nippon Loctite Co., Ltd.) was applied to the surfaces of the joint surfaces 13 and 13, and after about 30 seconds, the liquid photosensitive resin APR F- Instead of 47, liquid photosensitive resin APR F-91 was injected, and the plate bonding operation and the bonding strength of the obtained product were measured in the same manner as in Example 1. The fracture toughness of the joint surface is 64.1% Kg.
/ Cm ² and a sufficient bonding strength, and the junction of the printing plate was printed surface is not printed on any problem.

[0016]

Example 3 Photosensitive resin printing plate (trade name: APR F-47 for corrugated board printing plate, manufacturer: Asahi Kasei Corporation)
Was used to plate-connect the printing plates in the same manner as in Example 1. At this time, a plate was prepared in the same manner as in Example 1 except that a modified acrylate UV adhesive (trade name: Loctite 358, manufacturer: Nippon Loctite Co., Ltd.) was applied to the surfaces of the joint surfaces 13, 13 instead of cyanoacrylate. And the bonding strength of the obtained one was measured. The toughness of the obtained joint surface was 63.9% · Kg / cm ^2, which was a sufficient joint strength, and the trace of the joint portion of the printing plate was a printing surface without any problems in printing.

[0017]

[Example 4] Photosensitive resin printing plate (trade name: APR F-91 for corrugated board printing plate, manufacturer: Asahi Kasei Corporation)
Using plate hardness Shore A 40 °, instead of liquid photosensitive resin F-91 (plate hardness Shore A 40 °) for plate connection, liquid photosensitive resin APR K-11 (plate hardness Shore A55
°, manufacturer: Asahi Kasei Kogyo Co., Ltd. was used, and the bonding treatment was performed in the same manner as in Example 3 (using modified acrylate UV adhesive). The toughness of the joint portion of the printing plate thus obtained was 44.5% · Kg / cm ² ,
Sufficient adhesion was obtained. When printing was performed on a corrugated cardboard flexographic printing machine using this printing plate, a trace of the joint was hardly noticeable, and a printed matter having practically no problem was obtained.

[0018]

Comparative Example 1 The same printing plate as in Example 1 was used, and the joining operation and treatment were carried out in the same manner as in Example 1 except that cyanoacrylate was not applied to the surfaces of the joining surfaces 13 of each other. The toughness was as low as 8.9% · Kg / cm ² , and the interface between the bonding surface 13 and the cured portion of the photosensitive resin stock solution 30 was broken, so that sufficient interfacial adhesion was not obtained.

[0019]

Comparative Example 2 Using the same printing plate as in Example 1, the bonding surfaces 13, 13 were brought close to each other to narrow the groove 15 in FIG. 2E, the cyanoacrylate used in Example 1 was filled, and then the plate was used. A printing plate was obtained by irradiating with ultraviolet rays without using the liquid photosensitive resin APR F-47 for tie. The toughness of this printing plate varied greatly depending on the location, and the weak portion of the joint was not practically satisfactory as a printing plate.

[0020]

Comparative Example 3 In Example 3, a modified acrylate UV adhesive (trade name: Loctite 358, manufacturer: Loctite Japan) was injected, and then the liquid photosensitive resin APR was used.
The toughness of the joint part of the joint plate obtained without using F-47 was 57.2% Kg / cm ^2, and although the improvement of the adhesive strength was observed, the trace of the joint surface appeared on the printed surface. It was bad.

[0021]

According to the joining method of the present invention, not only can a plurality of printing plates be produced by connecting a plurality of them, but also the strength of the joining portion can be dramatically increased. Since the resin of the same property as the printing plate has almost the same properties as the printing plate, there is almost no effect on the printing quality of the joint part, and the strength of the joint part increases dramatically, so there is no fear of the joint part of the plate breaking during handling. In addition, it is possible to significantly improve workability and produce a larger printing plate.

[Brief description of drawings]

FIG. 1 is a perspective view showing a pair of printing plates to be joined in the present invention.

FIG. 2 is a process explanatory view of a joining method according to the present invention.

[Explanation of symbols]

 1 printing plate 2 single-sided adhesive tape 3 plate connecting part 4 relief part 11 shelf part 12 base part 13 printing plate joining part 13 'plate connecting monomer applying part 14 printing plate surface 15 groove 20 single-sided adhesive tape 30 plate connecting resin filling part

Claims (2)

[Claims] 1. An abutting end face of a plurality of photocurable resin printing plates is abutted, the end faces of the abutting respective printing plates are treated with a monomer having a (meth) acrylic group in the molecule, and then the end faces are treated. A plate connecting method for flexographic printing plates, which comprises irradiating ultraviolet rays after injecting a liquid photo-curable resin into a gap formed between them. 2. A plurality of photocurable resin printing plates are abutted with adjacent end faces thereof, and each of the abutted end faces of the printing plate is treated with a monomer having a cyanoacryl group in its molecule, and then the end faces are joined together. A plate connecting method for flexographic printing plates, which comprises irradiating ultraviolet rays after injecting a liquid photocurable resin into the gaps to be formed.