JP2001310570A - Blanket for printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blanket for printing being adeauately adhesive and durable against the repeated compression even in a high-speed printing. SOLUTION: In the blanket for printing having at least a supporting layer under the layer for the printing surface, a warp of the woven fabric forming the aforementioned supporting material-layer is characterized by a vinylon-thread spanned by a solvent-used wet spinning method under the condition of a cooled gelation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing blanket used in an offset printing machine, and more particularly, to an improved adhesiveness between a surface layer serving as a printing surface and a support layer, and excellent durability against repeated compression. Printing blanket.

[0002]

2. Description of the Related Art In offset printing, an image is transferred from a printing plate to a blanket once, and the image transferred to the blanket is printed on paper. Therefore, if the blanket mounted on the blanket cylinder is loosened or misaligned during operation, the printed image is shifted. For this reason, the printing blanket must not only be easily mounted on the blanket cylinder, but also must be securely fixed after mounting. Such a printing blanket is provided, for example, by providing a compressible layer on a reinforcing layer of a plurality of woven fabrics, and further laminating a surface layer to be a printing surface on the compressible layer via a support layer. .

A compressible printing blanket is, for example, shown in FIG.
As shown in FIG. 1, a compressible layer 5 which is a foam layer is formed on the lower surface side of a surface layer 1 serving as a printing surface via a support layer 3 made of one layer of woven fabric. The cloth 7 is supported by a support layer 9 formed by laminating three layers. The blanket woven fabric constituting the support layer 9 is a woven fabric made of cotton yarn that has been subjected to stretch processing to obtain shape stability after the blanket has been mounted on the blanket cylinder and has a small residual elongation. Have been.

[0004] As the support layer 3 laminated on the lower surface of the surface layer, a woven fabric having a certain residual elongation is used in consideration of ease of mounting on a blanket cylinder. Further, in order to reduce the influence of the texture on the surface layer,
A woven fabric using fine yarn is used. For the support layer laminated on the lower surface of such a surface layer, a woven fabric made of cotton yarn alone, a blend of cotton yarn and rayon yarn, rayon yarn alone, etc. is used in consideration of the adhesiveness to the surface layer.

[0005]

However, with the speeding up of the printing press, the conventional printing blanket has the following problems. That is, as the speed of the printing press increases, the frequency of the repetitive compressive stress applied to the blanket increases, and the degree of fatigue near the surface layer and the lower surface thereof increases. When the degree of fatigue increases, first, the support layer 3 adjacent to the surface layer 1 breaks, and the surface layer 1 further breaks due to the breakage of the support layer 3.

In particular, in order to mount a blanket, both ends are fixed to a slit provided in a blanket cylinder, so that an edge portion (a portion which is sharply bent at a corner of the slit) or a printing paper passes. Compressive stress concentrates at the boundary portions on both sides of the printing paper when the printing is performed. Therefore, the breakage of the blanket often occurred at the edge of the blanket cylinder or at the boundary of the printing paper. Therefore, in the field of high-speed printing, there is a demand for a blanket having durability against repeated compression, in other words, good press life.

When such a breakage of the blanket occurs, the blanket needs to be replaced, and the printing efficiency (productivity) is increased.
Greatly worsens. However, conventionally used woven fabrics made of cotton or rayon have insufficient fatigue resistance against repeated compression, and have a problem in durability against repeated compression during high-speed printing. Therefore, in order to increase the durability of the support layer, it is conceivable to use a high-strength raw yarn such as an aramid yarn or a carbon yarn. However, there is a problem from the viewpoint of reduced adhesiveness and economy.

From the viewpoint of economy, vinylon yarn is excellent, has good wettability with rubber, and can be expected to have improved adhesion to the surface layer. However, conventional vinylon yarn is
Because of the wet spinning, the fiber length was short, and a fine-count yarn could not be formed. Therefore, with the vinylon yarn, a smooth woven fabric with a fine count that does not affect the texture of the surface layer could not be obtained.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing blanket having sufficient adhesiveness against repeated compression and printing durability even in high-speed printing.

[0010]

The present invention has the following configuration to achieve the above object. That is, a printing blanket according to the present invention is a compressible printing blanket having a support layer provided between a surface layer serving as a printing surface and a compressible layer, wherein a warp of a woven fabric forming the support layer is provided. Is formed by vinylon yarn which is a spun yarn by a solvent wet cooling gel spinning method.

A vinylon yarn, which is a spun yarn obtained by a solvent wet cooling gel spinning method, is a high-strength spun yarn with a long count of long fibers. The weft yarn may be a vinylon yarn which is a spun yarn by the same solvent wet cooling gel spinning method as the warp yarn,
It may be used in combination with conventional cotton, rayon, polynosic, polyester and the like. The warp contributes a great deal to the adhesion to the surface layer, and the vinylon yarn, which is a spun yarn obtained by a solvent wet cooling gel spinning method, improves the wetting with rubber and increases the adhesion. Since vinylon yarn, which is a spun yarn obtained by the solvent wet cooling gel spinning method, is a fine-count spun yarn, a smooth woven fabric having little effect on the surface layer of the woven fabric can be obtained.

The surface layer of the blanket according to the present invention comprises:
Oil-resistant polymers are used in consideration of printing inks, ink cleaning agents, etc., for example, chloroprene rubber (CR), polysulfide rubber (T), polyacrylonitrile-butadiene rubber (NBR), fluoro rubber (FKM), silicon rubber (Q) and the like. Such an oil-resistant polymer may be one to which one or more of a vulcanizing agent, a vulcanization accelerator, a reinforcing agent, an antioxidant and the like are added.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described.
First, as the blanket, a blanket having a normal structure shown in FIG. 1 is manufactured, and the warp and the weft of the woven fabric forming the support layer 3 close to the surface layer 1 are as shown in Table 1. Claron K2 EQ2 used in Examples 1 and 2 is a vinylon yarn obtained by Kuraray's solvent wet cooling gel spinning method.
Here, the warp means the rotation direction of the blanket when the blanket is mounted on the blanket cylinder, and the weft means the axial direction of the blanket cylinder.

[0014]

[Table 1]

The breaking strength in the warp direction of the support layers used in the above comparative examples and examples was measured. The measuring method conformed to DIN53354. Sample size is 50m width
mx 320 mm in length, 200 mm in mark interval, and 100 mm / min tensile speed. Table 2 shows the measurement results.
As is clear from the table, the support layers of the examples have extremely enhanced breaking strength as compared with the comparative examples.

[0016]

[Table 2]

Next, the adhesive strength between the support layer and the surface layer in the warp direction of the support layer was measured. The measuring method was based on JIS K6256 "Peeling test of cloth and vulcanized rubber". For the sample size, a 25 mm wide x 150 mm long lined with a cloth backed with an instant adhesive to reinforce the surface layer was used, and the tensile speed was based on JIS K6256 "Peeling test between cloth and vulcanized rubber". I went. Table 3 shows the measurement results. As is clear from the table, the adhesive strength of the example was improved as compared with the comparative example, and the damage state was also cohesive failure of the surface layer in the example, and the adhesion between the surface layer and the woven fabric was good. .

[0018]

[Table 3]

Next, a repeated compression fatigue test was performed as follows. As the compression fatigue tester, a bearer contact type compression / rotation tester in which the impression cylinder and blanket cylinder units of the printing press were modified was used. The impression cylinder and blanket cylinder had a diameter of 173 mm and a surface length of 414 mm.

The test was performed as follows. First,
An underlay is attached to the blanket cylinder so that the amount of compression of the blanket at the nip is 0.10 mm, and the blanket is stretched over the cylinder. Next, after rotating for several minutes, retightening is performed, and one sheet of 0.25 mm thick paper is stuck on the surface of the impression cylinder. Thereafter, the test machine is rotated at a high speed of 1000 rpm. After 5000 revolutions, stop the tester and observe the blanket surface.

If no problem such as breakage or cracking is observed on the surface, the paper is removed when the rotation is further continued and after a total of 10,000 rotations, and the thickness of the surface of the impression cylinder is reduced to 0.25 mm again.
The above test was carried out by attaching one sheet of paper, and the test was repeated every 10,000 times.

Table 4 shows the test results. As is clear from the table, in the example, the number of rotations until crack generation was clearly increased as compared with the comparative example, and the compression fatigue resistance was improved.

[0023]

[Table 4]

[0024]

As described in detail above, the present invention improves the adhesion to the surface layer without impairing the smoothness of the support layer, strengthens the support layer, and repeatedly compresses the print layer during high-speed printing. , That is, a blanket excellent in printing durability.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view illustrating an example of a blanket.

[Explanation of symbols]

 Reference Signs List 1 surface layer 3 support layer 5 compressible layer 7 woven fabric 9 support layer

Claims (1)

[Claims] 1. A compressible printing blanket comprising a support layer provided between a surface layer serving as a printing surface and a compressible layer, wherein the warp of the woven fabric forming the support layer is subjected to solvent wet cooling gel spinning. A printing blanket formed by a vinylon yarn which is a spun yarn by a spinning method.