JPH049189Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Purpose of invention]

[Industrial Field of Application] The present invention is a blanket for a printing press, more specifically, the blanket body is protected from the swelling effect of printing ink and cleaning liquid, and it also protects the blanket from the stress caused by contact with the plate cylinder and the paper surface to be printed. This invention relates to a printing press blanket with an effective absorption function. [Prior Art] As shown in Figure 2, conventional general printing blankets are made of oil-resistant rubber such as acrylonitrile-butadiene copolymer rubber (NBR) or chloroprene rubber (CR) or synthetic resin such as polyurethane. A structure in which a surface printing layer 2 made of elastomer is supported by a support layer 3 consisting of one or multiple woven fabric layers made of cotton cloth or synthetic fibers such as polyester or polyamide or semi-synthetic fibers such as rayon, and A structure in which a compressible layer 4 made of sponge rubber, plastic foam, rubber mixed with a large number of microcapsules, etc. is interposed between the surface printing layer 2 and the support layer 3 or between each support layer 3 as shown in the figure. (see Figure 3). However, with the above-mentioned known blankets, during cleaning work after printing is completed (this work is done with the blanket still wrapped around the blanket cylinder of the printing machine), the cleaning liquid may enter between the back surface of the blanket and the cylinder. It causes the support layer or the rubber elastic material covering it to swell, causing delamination of the support layer, a local increase in the thickness of the blanket, or a local variation in the compressive stress, and as a result, only deteriorating the print finish. First, the lifespan of the blanket itself is significantly shortened. Therefore, in order to avoid the negative effects caused by the intrusion of the cleaning liquid, as shown in Utility Model Publication No. 51-13925, Utility Model Application Publication No. 57702-1980, and Publication Utility Model Publication No. 52-7206, both edges of the blanket are made oil-proof. A technique has been proposed in which cleaning liquid is prevented from entering the back side of the blanket by coating it with rubber. However, the thickness of the side edges of the blanket is at most 1.6~
1.9 mm, the area of the contact area with the blanket body is 130 x 200 to 300 mm, so even if these proposed technologies are somewhat useful in preventing delamination, they cannot be applied to the vast blanket/blanket body. It does not help to avoid the influence of cleaning fluids from contact points. Furthermore, as a separate proposal, there is a method of interposing a tear-resistant and low-stretch protective layer such as polyethylene terephthalate on the lower surface of the surface printing layer (Japanese Patent Application Laid-Open No. 56-67295), or Attempt to configure the contact layer with a magnetic metal layer (Utakkai 52
-131104) has also been proposed. However, since the blanket in an offset printing machine is subjected to strong shearing and compressive forces when it comes into contact with the plate cylinder and the paper surface to be printed, a function to alleviate these stresses is essential, and it is necessary to have a function to alleviate these stresses. It's hard to depend on. The above-mentioned Japanese Patent Application Publication No. 1983
In the structure of No. 67295, the hard polyethylene terephthalate film layer under the surface printing layer has the property of resisting shear stress;
Rather, it inhibits the relaxation of compressive stress. Also, Mikiakiaki
Since the structure of No. 52-131104 is provided with only a surface rubber layer, the rubber layer is solely responsible for absorbing stress, resulting in a very short life span of the blanket. [Problems to be solved by the invention] Therefore, the problem to be solved by the present invention is to create a printing press blanket that simultaneously satisfies the two problems of stress relaxation and absorption in the printing press blanket and prevention of swelling caused by the intrusion of cleaning liquid. It is to provide.

[Structure of the idea]

[Means for Solving the Problems] (1) Concept The inventor of the present invention pursued a structure that expected the basic performance required of printing press blankets, especially the ability to quickly alleviate compressive and shear stress. As a result, it was found that it is desirable to place a porous compressible layer with high compressive stress relaxation performance below the surface printing layer, but from the standpoint of cleaning liquid resistance, the presence of this layer is rather important because the cleaning liquid does not penetrate inside. It was discovered that the compressed layer is extremely brittle and becomes a problem if it penetrates, and as a result of further studies on means to avoid this problem, the present invention was arrived at. (2) Overview Based on the above knowledge, the printing press blanket according to the present invention has a rubber surface printing layer and an oil-resistant and oil-resistant layer on both sides of a porous compressible layer, respectively, with a tensile support layer interposed therebetween. It is characterized by comprising a solvent-based blanket body contact layer. Below, the main elements related to the structure of the invention will be explained in sections. (3) Porous compressible layer The porous compressible layer is located at the center of the blanket of the present invention and is a layer for buffering compressive stress. This layer is formed by a porous material foamed using a foaming agent, a microcapsule, a porous material made of a rubber elastic material mixed with pieces of foamed material or crushed pieces of cork, or a porous material made by a leaching method. Constructed using porous materials. (4) Support layer The support layer is located on both sides of the above-mentioned compressible layer, and mainly functions to relieve the stress applied to the surface printing layer during printing and transmit it to the compressible layer. This thing is
As in the case of conventional blankets, one or more woven fabric layers made of cotton cloth or synthetic fibers such as polyester or polyamide or semi-synthetic fibers such as rayon are printed using rubber glue or other adhesives as described below. layer and said porous compressible layer. (5) Surface printing layer The surface printing layer, which comes into direct contact with the plate cylinder and paper sheets, is made of an oil-resistant elastic material such as oil-resistant rubber such as NBR or CR or polyurethane elastomer, similar to conventional blankets. However, if desired, a composite structure can also be provided in which a thin plastic layer is laminated on top of this layer. (6) Blanket cylinder contact layer (protective layer) The blanket cylinder contact layer (protective layer) is located below the lower support layer of the above two support layers, and is in direct contact with the blanket cylinder. parts, which protect the support layer, the compressible layer and the surface printing layer from swelling by the washing liquid. This layer is composed of a plastic film such as polyethylene terephthalate, polyamide, polyvinyl chloride, polyethylene, polypropylene, or a metal foil such as aluminum foil or steel foil,
Its thickness is 100μm or less, tensile strength (2%
M'd) 5 to 20 kg/cm is preferred. (7) Sealing As an additional feature of the present invention, the side edges of the blanket may be sealed with an oil-resistant rubber material, as shown in the examples below. According to this configuration, the internal porous compressible layer and the support layer are completely shielded from the cleaning liquid, so that the swelling resistance becomes even better. [Function] Since the printing press blanket of the present invention has a porous compressible layer in the center, the stress applied to the surface printing layer during printing is completely absorbed. Moreover, since the support layers are present on both sides of the compressible layer, the weak point in strength of the former is covered. In addition, since there is a cleaning liquid-resistant protective layer below the lower support layer in the area in contact with the blanket body, the cleaning liquid does not penetrate into the porous compressibility, which has weak cleaning liquid resistance. As a comprehensive effect of the above-mentioned functions, the blanket of the present invention has the following effects: good transfer characteristics, long service life, and excellent swelling resistance against cleaning fluids. [Example] Examples of the embodiment of the invention will be described below using examples, but the examples are merely for explanation and are not intended to limit the spirit of the invention. FIG. 1 is a partially enlarged sectional view of an embodiment of a printing press blanket according to the present invention. The blanket 1 of this example has support layers 3a and 3b made of cotton fabric on both sides of a compressible layer 4 at the center, and a surface printing layer 2 made of NBR and a protective layer made of aluminum foil on the outside of each support layer 3a and 3b, respectively. 3' has a laminated and integrated structure. In addition, blanket 1
The side edges of are covered with a sealing material 5 made of urethane rubber. The blanket 1 of this example has the above structure, and the stress received during printing is relaxed and absorbed by the compressible layer 4 in the center, so it has good transferability and the layer 4 is sandwiched in a sandwich pattern. Support layer 3
a and 3b are sufficient in terms of strength, and since the contact portion with the blanket body is covered with an oil-resistant aluminum foil protective layer 3', the compressible layer 4
It has the feature that it is difficult to be attacked by cleaning solvents. Note that the sealing material 5 may be omitted as appropriate.

[Effect of the idea]

As explained above, the present invention has contributed to the printing industry by providing a printing press blanket that simultaneously satisfies the two issues of stress relaxation and absorption and prevention of swelling due to the intrusion of cleaning fluid. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of an embodiment of a printing press blanket according to the present invention, and FIGS. 2 and 3 are similar sectional views of known printing press blankets. The meanings of the symbols in the figure are as follows: 1...The entire blanket for a printing press of the present invention, 2...Surface rubber layer, 3a, 3b...Support layer, 4...Compressible layer,
5...Sealing material.

Claims (1)

[Claims for Utility Model Registration] 1. A rubber surface printing layer and an oil- and solvent-resistant blanket cylinder contact layer are provided on both sides of the porous compressible layer through a tensile support layer, respectively. A printing blanket characterized by: 2. The printing press blanket according to claim 1, wherein the side edges are covered with an oil- and solvent-resistant sealing material.