JPH07110557B2 - Printing blanket and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing blanket and a manufacturing method thereof, and more particularly to a surface shape of a surface printing layer and a manufacturing method thereof.

[0002]

2. Description of the Related Art In an offset printing machine, a blanket cylinder is equipped with a printing blanket having a surface printing layer on the printing plate side, and the printing plate is supplied with dampening water from a water supply device and ink from an inking device. Then, the ink image on the plate is transferred to a blanket, and this image is printed on the printing paper passing between the impression cylinder. In such a printing blanket, a compressible printing blanket provided with a compressive layer,
Although a non-compressible printing blanket without a compressive layer is used, the quality of a printed image is affected by the fine unevenness of the blanket surface in any blanket.

In a conventional general blanket manufacturing method, talc is used to prevent the surface rubber from sticking to the vulcanized paper during vulcanization. That is, if the vulcanized paper is directly laminated on the surface rubber after applying the surface rubber, the vulcanized paper will not come off after vulcanization, so talc is dusted on the surface rubber to prevent sticking, and the vulcanized paper is then applied. It is rolled up while being sandwiched.

Referring to FIG. 4, a conventional method for producing a compressible printing blanket will be described. First, a cotton cloth, rayon cloth, polyester cloth or the like is glued with a rubber paste to form two to three layers.
The support 2 is formed by stacking layers, and the compressive layer 4 is provided on the support 2. Further, an oil-resistant surface rubber layer 8 serving as a printing surface is applied on the compressible layer 4 via a support 6 made of cotton cloth. Next, the surface rubber layer 8 is dusted with talc 10 to be subjected to an anti-adhesion treatment. When the talc 10 is dusted on the surface rubber 8, immediately after that, the vulcanized paper 12 such as art paper is sandwiched and wound around a roll.

Then, it is vulcanized in a state of being wound up on a roll, and is rewound to remove the vulcanized paper 12 for which vulcanization is completed. At this time, since talc is dusted between the surface rubber 8 and the vulcanized paper 12 to prevent adhesion, the vulcanized paper 12 can be smoothly peeled off. When the vulcanized paper 12 is peeled off, the surface is finally ground by a sanding machine such as a sandpaper grinder, and the surface is formed into a fine uneven surface having a predetermined roughness. As for the surface roughness, a 10-point average roughness is usually formed to be 2 μm to 15 μm with a stylus type roughness meter.

[0006]

As described above, the manufacturing method using talc for preventing the adhesion between the surface rubber 8 and the vulcanized paper 12 has the following problems. From the aspect of blanket quality, there was a problem that the print quality was not stable. That is, since talc is not only attached to the surface but also completely embedded in the surface rubber 8, it is difficult to completely remove the talc even by polishing when forming the surface. Therefore, talc often remains attached to the printed surface, and talc hinders ink transfer. Therefore, it was necessary to print a considerable number of sheets before the talc was completely removed and the print quality was stabilized. Further, the talc causes clogging of the polishing paper, so that a predetermined surface roughness cannot be obtained.

From the viewpoint of working environment, dust is generated during dusting and removal of talc, which deteriorates environmental hygiene, and the production equipment is heavily soiled, so environmental hygiene is protected and product quality is maintained. To do this, cleaning must be done frequently. Therefore, there is a problem that work efficiency is reduced. Further, there is a problem that the cost is increased in terms of cost. That is, in order to reduce the adhesion of talc by polishing, a large polishing allowance must be taken. If a large polishing allowance is taken, it takes much polishing time and naturally the cost increases.

Further, when the surface shape of the surface printing layer is formed by polishing, not only the polishing process increases and the cost increases, but also it can be formed only on the irregular uneven surface. There is a problem that so-called beards are formed, so that the ink is applied well and solid printing is good, but the reproducibility of halftone dots is poor.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a printing blanket which can obtain a stable printing quality with an arbitrary uneven shape without polishing the surface and a method for producing the printing blanket. is there.

[0010]

In order to achieve the above object, the present invention has the following constitution. That is, in a blanket having at least one support and a surface layer to be a printing surface, the surface layer is formed of a photocrosslinkable composition, a rubber layer is provided on the lower surface, and the surface layer has an uneven shape. It is characterized by Then, as a method of forming the uneven shape of the surface layer, a photocrosslinkable composition is coated on the rubber layer to form a surface layer, and the surface layer is crosslinked, and then the surface layer is powdered. Alternatively, a granular material is attached, and then the powdery material or the granular material is vulcanized by being wound into a roll so as to be embedded in the surface layer.
The surface layer can be formed into an uneven shape by removing the powdery or granular material after vulcanization. Further, as another manufacturing method, a surface layer is formed by coating a photocrosslinkable composition on a rubber layer to form a surface layer, and after the surface layer is crosslinked, the surface layer has an uneven surface. The sheet for application may be pressure-bonded for vulcanization, and after the vulcanization, the surface-forming sheet may be peeled off to form the surface layer in an uneven shape.

[0011]

Since the surface layer itself is formed in a concavo-convex shape, the adhesive surface of the rubber layer provided on the lower surface has a concavo-convex shape according to the surface layer. Further, in the manufacturing method, the surface layer is cross-linked but has flexibility, and the rubber layer provided on the lower surface is before vulcanization, so powders or granules are embedded and removed after vulcanization. When this is done, the dents due to the powdery or granular material are retained as they are, and an uneven surface layer is formed. Further, when a surface forming sheet is used instead of the powdery material or the granular material, the uneven surface of the surface is traced on the surface layer by the sheet.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A printing blanket according to the present invention is shown in FIG.
As shown in FIG. 2, for example, a cotton cloth is glued with rubber paste and laminated in two layers to form a support 20, and a compressive layer 21 is formed thereon.
After the formation of the above, the oil resistant rubber layer 25 is further laminated on the compressive layer 21 via the support 23 made of cotton cloth, and the uneven surface layer 27 is formed on the rubber layer 25. It has become.

For the supports 20 and 23, well-known woven cloth such as rayon cloth and polyester cloth can be used in addition to cotton cloth, and the rubber layer 25 can be made of, for example, chloroprene rubber, nitrile rubber, acrylic rubber or the like. It is used by adding one or more of vulcanizing agents such as sulfur, vulcanization accelerators, and antioxidants to the oil-resistant rubber of, and a thickness of 0.2 to 0.8 mm can be obtained by a spreader, knife coater, roll coater, etc. Is applied and laminated. The surface layer 27 can be formed of a photocrosslinkable rubber composition containing a photosensitizer or a photosensitive resin. A photo-crosslinkable rubber composition or photosensitive resin comes into contact with a printing ink and comes into contact with an object to be printed, so that it has elasticity, oil resistance, good compression set and excellent adhesion to a rubber layer. Is preferred.

Since the surface layer 27 is formed not only on the upper surface but also on the entire surface in a concavo-convex shape, the bonding surface of the rubber layer 25 adhered thereto is also a concavo-convex surface. The concavo-convex shape of the surface layer 27 can be arbitrarily formed according to the size or shape of the concavo-convex shape of the powdery or granular material used, or the surface shape sheet.

Next, a method of forming the uneven shape of the surface layer 27 will be described with reference to FIG. First, a description will be given of a forming method using a powdery material or a granular material. To form a support 20 by laminating two layers of cotton cloth, which is glued with rubber paste, and forming a compressive layer 21 thereon, Further, the compressible layer 21
Oil-resistant rubber layer 25 through a support 23 made of cotton cloth on top of
Is applied and laminated. Then, a photocrosslinkable rubber composition obtained by adding a photosensitizer or a photosensitive resin is coated on the rubber layer 25 to form a surface layer 27. The surface layer 27 may have any thickness as long as it can form a thin film capable of preventing adhesion of powdery or granular materials.
The thickness can be 1 to 15 μm. The surface layer 27 is cross-linked by being irradiated with ultraviolet rays to form a cured thin film layer.

After curing the surface layer 27, the surface layer 2
A powder or granular material 29 is attached to 7. As the powdery or granular material 29, for example, talc, powdery alumina, powdery carbon, glass beads or the like can be used. After adhering the powdery or granular material 29 and scraping off the excess material, the process proceeds to the vulcanization step of the rubber layer 25.

Vulcanization is carried out by winding on a roll as in the conventional case. In order to prevent the powdery material or granular material 29 from falling when it is wound on a roll and to make it evenly and surely slip into the surface layer 27, an art paper or the like is applied onto the powdery material or granular material 29. It is preferable to sandwich the sulfur paper 31. When pressed at the time of winding, the powder or granular material 29 is embedded in the surface layer 27, but the surface layer 27 itself is also pressed by the powder or granular material 29 and embedded in the rubber layer 25. In this way, the powder or granular material 29 is vulcanized while being embedded in the surface layer 27.

When the vulcanization process is completed, the process proceeds to a separation process for removing the powdery or granular material 29 and the vulcanized paper 31. This separating operation may be performed by peeling the vulcanized paper 31 while winding the roll in the opposite direction and scraping off the powdery or granular material 29. Since the surface layer 27 has already been crosslinked and hardened before winding the vulcanized paper 31, the vulcanized paper 31 can be easily peeled off without sticking. Further, since the powdery material or the granular material 29 is merely embedded, it is not completely buried, so that it can be easily removed. It is preferable to remove the powdery or granular material 29 while applying tension.

When the powder or granular material 29 is removed, the surface layer 27 is formed with a fine uneven surface in which the powder or granular material 29 is embedded. Since the rubber layer 25 is cured by vulcanization, the uneven surface is maintained as it is, and the surface layer 27
The upper surface of the can be a fine uneven surface. The shape of the uneven surface can be arbitrarily selected according to the shape and size of the powdery or granular material 29 used.

Next, a method of forming the uneven shape of the surface layer using the surface forming sheet will be described with reference to FIG. The surface forming sheet is used in place of the above-mentioned powdery material or granular material 29. Therefore, the same process as the above is performed until the surface layer 27 made of a photocrosslinkable rubber composition or a photosensitive resin is formed and irradiated with ultraviolet rays to be crosslinked.

After curing the surface layer 27, the surface layer 2
The surface forming sheet 33 is pressure-bonded to 7. The material of the surface forming sheet is not particularly limited, and a plastic sheet, a rubber sheet, a paper sheet or the like can be appropriately selected and used. As the plastic sheet, a polyester resin sheet, a polyamide resin sheet or the like is preferable, and in the case of a rubber sheet, it is preferable to use a sheet backed with a base fabric to prevent the sheet from stretching. The surface of the surface forming sheet is ground by a grinder, embossed or shot blasted to obtain a surface roughness of 2 μm with a stylus type roughness meter.
˜15 μm, preferably 5 μm to 7 μm.

The surface-forming sheet 33 thus formed is vulcanized while the uneven surface is pressure-bonded to the surface layer 27.
The surface forming sheet 33 can be pressure-bonded by winding it on a roll, and the use of vulcanized paper can be omitted up to the powdery body unlike the above case where the granular body 27 is used. In this manner, the surface forming sheet is vulcanized with the uneven surface embedded therein. The surface forming sheet 31 may be peeled off after the vulcanization is completed. The surface forming sheet 31 can be easily peeled off without sticking because the surface layer 27 is cross-linked when the roll is wound in the opposite direction. Thus, when the surface forming sheet 31 is peeled off, the unevenness traced on the surface layer 27 is formed.

In the above-mentioned forming method, the surface forming sheet 31 can be repeatedly used, and the printing surface of the blanket is made into an uneven surface having an arbitrary roughness by appropriately selecting the unevenness of the surface. You can Further, conventionally, the gas generated from the rubber layer 25 during vulcanization may be partially concentrated to deteriorate the surface. However, when the surface forming sheet 31 is used, the gas is generated from the rubber layer 25. Since the surface layer 27 is cross-linked in advance, the gas is absorbed again in the rubber layer 25 without being concentrated at the interface with the sheet 31, and the deterioration of the surface can be prevented.

The present invention does not limit the structure of the blanket. Therefore, it does not matter whether it is a compressible printing blanket or a non-compressible printing blanket, but instead of a woven fabric as a support, a paper sheet that is strong and has high tensile strength, such as rubber-impregnated paper, is used. One or more of kraft paper, chimpan paper, etc. can be used, and a high tensile strength plastic sheet may be laminated.

[0025]

According to the present invention, the following effects can be obtained. Since the surface layer is formed of the photo-crosslinkable composition, it is possible to obtain a printed surface having an arbitrary uneven shape without polishing the surface. Further, as a method for forming the uneven shape of the surface layer, by simply adopting the above method,
Moreover, a blanket with stable print quality can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a blanket according to the present invention.

FIG. 2 is a schematic explanatory view showing a manufacturing process of the present invention.

FIG. 3 is a schematic explanatory view showing a manufacturing process in another example.

FIG. 4 is a schematic explanatory view showing a conventional blanket manufacturing process.

[Explanation of symbols]

 20 Support 21 Compressible Layer 23 Support 25 Surface Rubber Layer 27 Surface Layer of Photocrosslinkable Composition 29 Powder or Granule 31 Vulcanized Paper 33 Surface Forming Sheet

Claims (3)

[Claims] 1. A blanket having at least one support and a surface layer to be a printing surface, wherein the surface layer is formed of a photocrosslinkable composition, a rubber layer is provided on the lower surface, and the surface layer is formed. A blanket for printing, characterized in that it has an uneven shape. 2. A rubber layer is coated with a photocrosslinkable composition to form a surface layer, the surface layer is crosslinked, and then a powder or granule is attached to the surface layer, and then the roll is rolled. It is possible to form the surface layer in a concavo-convex shape by removing the powdery material or the granular material after vulcanization by immersing the powdery material or the granular material into the surface layer for vulcanization. A method for producing a blanket for printing, which is characterized. 3. A rubber layer is coated with a photocrosslinkable composition to form a surface layer, the surface layer is crosslinked, and then a surface forming sheet having an uneven surface is pressure-bonded to the surface layer. A method for producing a printing blanket, characterized in that the surface forming sheet is vulcanized and vulcanized, and after the vulcanization, the surface forming sheet is peeled off to form an uneven surface layer.