JPH11105445A - Photosensitive flexographic plate material and manufacture of flexographic plate using the plate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexographic plate material with superior printability which is bonded to a photopolymerizable printing plate and can correct the thickness of the plate appropriately and upgrade its elasticity and further, is constructed of a light-weight support as well as a method for manufacturing a flexographic plate using the flexographic plate material. SOLUTION: The photosensitive flexographic plate material comprises at least, one elastomer binder, a photosensitive resin layer which is addition- polymerizable by an active ray and contains at least, one addition-polymerizable ethylene unsaturated monomer and a photoinitiator and a support layer made up of a polyurethane resin foam obtained by bonding the photosensitive resin layer with an adhesive composed mainly of chloroprene rubber, nitrile rubber or polyurethane resin and a polymer film having flexibility and tear resistance, as constituents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexographic printing plate using a photosensitive resin and a plate making method thereof.
More specifically, the present invention relates to a technique which is effective in obtaining high printing characteristics while adjusting the plate thickness and rubber elasticity of a flexographic printing plate composed of a photosensitive resin layer and a support and being lightweight.

[0002]

2. Description of the Related Art It is well known that a flexographic printing plate is suitably used for letterpress printing on a soft and easily deformable printing material such as a cardboard, a bag or a synthetic resin film. Photopolymerizable compositions have been used in the manufacture of printing plates for flexographic printing, which photopolymerizable compositions generally comprise an elastomeric binder, at least one photopolymerizable monomer and a photoinitiator. The photopolymerizable printing plate is generally configured such that a photosensitive resin layer is sandwiched between a support and a cover sheet or a multi-layer cover body. Is polymerized and insolubilized.
By treatment with a suitable solution, the unexposed portions of the photopolymerized layer are removed, leaving a printing relief for use in flexographic printing. The flexographic printing plate on which the printing relief is formed cannot be directly mounted on a printing press because the plate thickness does not match a commonly used printing thickness. For this purpose, a support having an appropriate thickness and an appropriate elasticity must be bonded to the back side of the photopolymerizable printing plate.

[0003] Therefore, a rubber material is conventionally known as a support used for adjusting the plate thickness and the elasticity of such a thin photopolymerizable printing plate. As a method of producing a flexographic printing plate from the photopolymerizable composition,
There is a method in which the photopolymerizable composition is mixed, formed into a sheet, and attached to a carrier sheet. Examples of the carrier sheet include a metal plate such as steel or aluminum, a sheet, a foil, a film or plate made of a synthetic resin or a polymer capable of forming a film, and a polyester film such as polyethylene terephthalate. The molded photosensitive layer and the support layer may be applied with an adhesive to the surface of the support after giving back exposure to the adhesive surface of the photosensitive layer, or the adhesive layer may be formed between the photosensitive layer and the support layer. After the step of applying pressure and pressing flat,
Main exposure, development or washing out and post-development processing (drying,
(Including post-exposure of the entire surface and partial removal of unexposed portions). The photopolymerizable printing plate thus manufactured is applied to at least one of the surface of the photopolymerizable printing plate and the rubber support using an organic solvent such as chlorinated trichlene, tetrachlorethylene, and ethyl acetate. Adhesion by laminating with rubber support,
I was in close contact.

[0004]

However, when a plate made of a rubber material is bonded to a photopolymerizable printing plate to produce a printing plate and printing is performed using the printing plate, there are the following problems.

[0005] (1) Printing problems • Poor dimensional accuracy • Narrow printing pressure range (2) Problems with mounting on printing plate cylinder • Heavy • Poor adhesion to carrier sheet • Ink Occurrence of transfer failure Such a problem occurs because, due to the processing method, it is difficult to adhere with appropriate strength to a base film made of, for example, a polyester film provided on the surface of the photopolymerizable layer. The reason for this is that when a cloth is used, the photopolymerized layer expands and contracts. Also,
A support made of a rubber material has excellent rebound resilience and compression set resistance, but has problems in energy absorption such as distortion and impact required in printing on cardboard, etc. The present invention solves the above-mentioned problems. It is an object of the present invention to provide (a) an addition-polymerizable, ethylenically unsaturated monomer, (b) a photoinitiator or a photoinitiator activated by actinic radiation, and ( c) The photosensitive composition comprising a thermoplastic elastomer binder is formed into a layer on a suitable casting foil, belt or platen, or is solvent-cast into a self-supporting sheet and extruded. Can be glued with a photopolymerizable printing plate made by calendering or pressing the composition at high temperature, can improve its plate thickness and elasticity well, Moreover, it is an object of the present invention to provide a flexographic printing plate comprising a lightweight support and having excellent printability, and a method for producing the same.

Another object of the present invention is to provide a support comprising a polyurethane resin foam having a photopolymerizable printing plate produced from the photosensitive composition and a polymer film having flexibility and tear resistance laminated on the surface thereof. An object of the present invention is to provide a flexographic printing plate which is hardly separated from each other by using an adhesive, has excellent printing pressure absorption and dimensional stability, and is reduced in weight, and a method for producing the same.

[0007]

According to the first aspect of the present invention, there is provided a photosensitive flexographic printing plate material comprising at least one elastomer binder, at least one addition-polymerizable ethylene-based polymer which is addition-polymerizable by actinic rays. A photosensitive resin layer containing a saturated monomer and a photoinitiator; and a polyurethane resin foam and a flexible resin, wherein the photosensitive resin layer is bonded by an adhesive containing chloroprene rubber, nitrile rubber or polyurethane resin as a main component. And a support layer made of a polymer film having resiliency and tear resistance.

[0008] A method for producing a flexographic printing plate according to a second aspect of the present invention comprises a method for preparing a photosensitive resin layer containing at least one elastomer binder, at least one photocrosslinkable ethylenically unsaturated monomer and a photoinitiator. A method for manufacturing a flexographic printing plate having a desired pattern formed by selectively exposing a flexographic printing plate material having an actinic ray to light and then developing an unexposed portion, comprising a polyurethane resin and a flexible and tear-resistant material. On one surface of a support made of a polymer film, an adhesive containing chloroprene rubber, nitrile rubber or polyurethane resin as a main component is applied to form an adhesive layer, and then the photosensitive resin layer is bonded to the adhesive layer. Adhesion, pressure bonding, image forming exposure by irradiating the photosensitive resin layer surface with active light through an image carrier, An exposure unit characterized by washout removed by the developer solvent.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The photopolymerizable composition for producing the photopolymerizable printing plate of the present invention comprises (a) an addition-polymerizable, ethylenically unsaturated monomer, and (b) an actinic ray. It consists of an activated photoinitiator or system and (c) a thermoplastic elastomer binder.

(A) Ethylene-based unsaturated monomers capable of addition polymerization. Monomers suitable for the practice of the present invention include those having one ethylenically unsaturated group and those having one or more ethylenically unsaturated groups. Those having an ethylenically unsaturated group. These examples include octyl acrylate, isodecyl acrylate, isodecyl methacrylate, 2-hexyloxyethyl acrylate, 1,4-butanediol diacrylate, 1,6-
Hexanediol methacrylate, 1,6-hexanediol methacrylate and trimethylolpropane triacrylate are included. (B) Photoinitiators or photoinitiators activated by actinic radiation Suitable initiators are, for example, α-methylbenzoin, benzophenone, benzylmethylketal, or ethyl-
Anthraquinone / 4,4'-bis- (dimethylamino)
-Includes benzophenone and the like.

(C) thermoplastic elastomeric binder block copolymers are suitable, an elastomeric block between two thermoplastic blocks, for example polystyrene,
A with, for example, polybutadiene or polyisoprene
/ B / A type. Preferred are linear and radical block copolymers with polystyrene end blocks, such as polystyrene / polyisoprene / polystyrene, (polystyrene / polybutadiene) ₄ Si or (polystyrene / polyisoprene) ₄ Si.

The photopolymerizable layer generally contains 65 to 95% by weight of a binder, 5 to 30% by weight of a monomer or monomer mixture and 0.5 to 5% by weight of an initiator. Furthermore,
The photopolymerizable layer can include other additives such as fillers, antioxidants and plasticizers.

[0013] Photopolymerizable printing plates can be prepared by all the usual methods using the above photopolymerizable composition.
As a preferred example, the photopolymerizable composition previously extruded is fed into a nip of a calender, and calendered between a carrier film made of polyethylene terephthalate and a cover element to form a photopolymerizable layer. .

The support of the present invention is a lightweight foamed material (foam material) made of a polyurethane resin which is excellent in dimensional stability and printing pressure absorption.
Gers R / bak® SS (thickness:
1.02 to 3.05 mm) or SF (thickness: 0.76)
To 4.57 mm). Further, a polymer film having flexibility and tear resistance and polyethylene terephthalate are laminated and adhered on the surface. This is for suppressing expansion and contraction of the photopolymerizable printing plate and further obtaining dimensional stability.

In the present invention, the photopolymerizable printing plate and the polyurethane foam are bonded to each other by using a chloroprene-based, nitrile rubber-based or polyurethane-based adhesive. Having a viscosity of 700 to 800 Pa · S / 20
° C., and coated on either surface of the photopolymerizable printing plate to be bonded and the support made of the foam material using a coating tool such as a brush or a roller, and then laminating both. Glue.

[0016] In this way, the thickness can be varied over a wide range in relation to the type of printing plate desired (thickness for thin plates: 0.05 to
0.17 cm, thick plate thickness: 0.25-0 / 64c
m) A support made of a polyurethane resin foam material is adhered to and press-bonded to a photopolymerizable printing plate, and a photopolymerizable printing plate to be used as a flexographic printing plate having a thickness of about 7 mm is laminated with the support. Obtained. In the case of bonding, a method of bonding and pressing immediately after applying the adhesive and after applying the adhesive and after a lapse of time, after reactivating the adhesive layer using a solvent such as trichlene, tetrachlorethylene, ethyl acetate, etc. Adhesion and pressure bonding methods can also be adopted.

Next, the plate material thus obtained is exposed to actinic rays for a specific portion of the photosensitive layer through an image-bearing original plate for about 15 to 20 minutes. At the width of the area exposed to actinic radiation, the ethylenically unsaturated monomers polymerize or crosslink and also crosslink with the binder, resulting in reduced solubility or swelling in aqueous developer solutions. Significant polymerization or crosslinking does not occur in the unexposed areas of the layer. The image-bearing master is composed of any suitable material, including cellulose acetate films and oriented polyester films.
Any light source and any kind of actinic ray can be used in the exposure step. The light rays can be emitted from a point source or in the form of parallel or divergent beams. Most commonly used free-radical generating systems activated by actinic radiation generally exhibit their highest sensitivity in the ultraviolet region. Therefore, the effect size of the light source should be given. The wavelength range is desirably 360 to 370 nm. The exposure temperature is preferably ambient or slightly elevated, ie about 20
C to about 35C. Following image exposure, the image is developed by washing out with a suitable aqueous developer. The aqueous developer can include an alkaline material, such as an alkali metal hydroxide, or can be an aqueous detergent solution. However, it is preferred to use only water. Aqueous developers can be heated to about 50 ° C. The development time can vary, but is preferably about 5
~ 25 minutes. The aqueous developer can be used in any conventional manner, including dipping, spraying and brush or roller application. Brush aids can be used to remove unpolymerized or uncrosslinked portions of the composition. Development can also take place in automatic processing equipment, which uses mechanical brushing and liquids to remove unexposed areas of the element. Following aqueous development, the relief printing plate is generally blotted or wiped dry and then dried in a forced air stream or in an infrared oven. Drying times and temperatures vary, but typically the plates are dried at 60 ° C for 5-30 minutes. High drying temperatures cause the support to shrink, which can cause alignment problems. The majority of flexographic printing plate materials are uniformly post-exposed to complete the photopolymerization and photocrosslinking processes and to ensure that the printing plate is stable during printing and storage. This post-exposure step utilizes the same active light source as the main exposure. Lastly, a part of the unexposed part of the photopolymerizable layer and a part of the support corresponding thereto are cut off. Cutting is
Usually, this is performed using a cutter, knife, scissors, or the like.

[0018]

The present invention will be described below with reference to examples. These do not limit the content of the present invention at all.

(Example) As described above, a photopolymerizable printing plate having a photopolymerizable layer having a thickness of 3 mm formed between PET films was used as MDR-S manufactured by DuPont.
(Hardness (JIS-A): 35, Compression set (%): 1)
1, rebound resilience (%): 67, water contact angle (°): 46,
Using a roughness average of 1.07), the base film was peeled off and R / bak (registered trademark) SF manufactured by Rogers was used.
Is adhered by using the chloroprene rubber-based adhesive described in detail above, and pressed with a plate having smoothness and appropriate weight such as glass or bakelite for about 30 minutes or more. In this manner, the plate material in a state where the photopolymerizable layer and the support made of the foam material are bonded to each other is subjected to pattern formation on the plate material surface as described above, and the unexposed portions are washed out, Drying and post-exposure treatment are performed, and by cutting and removing, a flexographic printing plate material having a thickness of about 7 mm is obtained.

[0020]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

(1) By integrally bonding the photopolymerizable layer and the support made of a foam material, excessive printing pressure can be absorbed, and fine printing pressure can be absorbed.

(2) By integrally bonding the photopolymerizable layer and the support made of a foam material using a chloroprene-based, nitrile rubber-based or polyurethane-based adhesive, the support is not peeled off from the photopolymerizable layer. .

(3) Since a foam material made of resin is used for the support, the weight can be reduced, the dimensional stability is excellent, and the carrier sheet can be easily attached to a printing machine.

Claims (2)

[Claims] 1. A photosensitive resin layer containing at least one elastomer binder, at least one addition-polymerizable ethylenically unsaturated monomer and a photoinitiator, which is addition polymerizable by actinic light, The resin layer is composed of a polyurethane resin foam bonded by an adhesive containing chloroprene rubber, nitrile rubber or polyurethane resin as a main component, and a support layer made of a flexible and tear-resistant polymer film. Characteristic flexographic printing plate material. 2. After selectively exposing a flexographic printing plate material having a photosensitive resin layer containing at least one elastomer binder, at least one photocrosslinkable ethylenically unsaturated monomer and a photoinitiator with actinic rays. In a method of producing a desired pattern-formed flexographic printing plate by developing an unexposed portion, a chloroprene rubber is provided on one surface of a support made of a polyurethane resin and a flexible and tear-resistant polymer film. After applying an adhesive containing nitrile rubber or polyurethane resin as a main component to form an adhesive layer, the photosensitive resin layer is bonded to the adhesive layer and pressed, and an image is formed on the surface of the photosensitive resin layer. Image formation exposure is performed by irradiating the carrier with actinic light, and unexposed portions are washed out and removed with a developer solvent. Manufacturing method of flexographic printing plate.