JP2540674B2 - Offset blanket for printing - 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 offset blanket, and more particularly to a printing offset blanket having a surface printing layer with improved high-speed printing suitability.

[0002]

2. Description of the Related Art A conventional offset blanket for printing has a surface printing layer on a support layer having or not having a porous compressible layer therein. A rubber material having high oil resistance, mainly an acrylonitrile-butadiene copolymer (NBR) is used for the surface printing layer.

However, when high-speed printing is performed using such a normal offset blanket, an adhesive force may be generated between the paper and the blanket, and the paper may be curled or broken. Similar problems occur when printing a smooth substrate such as coated paper. These are phenomena that occur because the so-called paper discharge property (paper separation property) is poor. When such trouble occurs,
Since the productivity is greatly reduced, it is required that the blanket used for these purposes has a good paper discharge property.

Therefore, in the conventional offset blanket, the surface of the surface printing layer is roughened or the rubber hardness of the surface printing layer is increased in order to improve the paper discharge property.
However, if the surface of the surface-printed layer is made rough, the halftone dot shape becomes poor and the dot reproducibility deteriorates. On the other hand, if the surface-printed layer becomes hard, the ink receptivity becomes poor and so-called solid crushing becomes worse.

On the other hand, a method of irradiating ultraviolet rays (Japanese Patent Application Laid-Open No. 51
-37706) and a method for treating chlorine (the same 47-5).
No. 1729), it has been proposed to improve the paper discharge property by surface treatment of the surface printing layer, but there are problems such as deterioration of working environment and increase in the number of steps. further,
Although a method of coating the surface layer with polyvinyl chloride, polyvinyl acetate, silicone rubber or the like has been proposed, there are problems such as an increase in the number of steps and deterioration of print quality as in the above.

Further, in addition to the paper discharge property, paper dust accumulated on the offset blanket due to printing for a long time is also a serious problem. That is, resource saving and recycling are progressing, and the percentage of using recycled paper is increasing year by year. However, since the quality of recycled paper is deteriorated, paper dust is easily generated. Then, when the paper dust is deposited on the offset blanket, problems such as deterioration of print quality and increase of cleaning work occur. In order to reduce the generation of such paper dust, it is necessary to improve the paper discharge property so that the printed paper is quickly separated from the offset blanket.

Therefore, an object of the present invention is to solve the above-mentioned technical problems, to improve the paper discharging property and reduce the paper dust residual property without deteriorating the printing quality or increasing the number of steps. To provide an offset blanket for printing.

[0008]

Means and Actions for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result,
When blending the polysulfide rubber with the oil-resistant rubber that constitutes the surface printing layer, the printing quality such as oil resistance of the surface printing layer, halftone dot shape and ink receptivity may be deteriorated or the number of steps may be increased. Without this, we obtained new knowledge that paper ejection performance can be significantly improved and paper dust residue can be reduced.
The present invention has been completed.

Therefore, the offset blanket for printing of the present invention comprises a support layer and a surface printing layer laminated on the support layer, wherein the surface printing layer comprises oil resistant rubber and polysulfide. 95: 5-6 by weight with rubber
It is characterized in that it is a layer composed of a mixture mixed at 0:40 . As the oil resistant rubber, in addition to the acrylonitrile-butadiene copolymer described above, synthetic rubber such as chloroprene rubber and polyurethane rubber can be used.

[0010] As the polysulfide rubber, Thiokol A is a polymer of ethylene tetrasulfide compound represented by the following formula _{(1), (-CH 2 -CH} 2 -S 4 -) n (1) the following formula Ethylene dichloride represented by (2) and bis-2-
Thiokol FA is a disulfide polymer of chloroethyl _{formal, (-CH 2 -CH 2 -S 2} -CH 2 -CH 2 -O -CH 2 -O -CH 2 -CH 2 -S 2 -) n (2 ) Thiocol ST, which is a polysulfide polymer of bis-2-chloroethylformal and 2% of trichloropropane.

The mixing amount of the polysulfide rubber to the oil resistant rubber is 95/5 to 60 by weight ratio of oil resistant rubber / polysulfide rubber.
Suitably, it is / 40, more preferably 95/5 to 85/15. If the mixing amount of the polysulfide rubber is smaller than the above range, the paper ejection property cannot be improved, and conversely, if it is larger than the above range, the halftone dot reproducibility and the ink receptivity are deteriorated.

The offset blanket of the present invention is shown in FIG.
As shown in FIG. 3, it comprises a support layer 2 and a surface printing layer 3 provided on the surface thereof. The support layer 2 is a rubber material (rubber glue).
It is made by laminating a plurality of layers of base fabrics 4a, 4b impregnated with at least one compressive layer 5 provided as necessary. The base fabrics 4a and 4b are woven fabrics such as cotton, polyester and rayon. Examples of the rubber material to be impregnated include acrylonitrile-butadiene rubber and chloroprene rubber. These rubber materials contain a predetermined amount of a vulcanizing agent, a vulcanization accelerator and, if necessary, a thickener. Then, the woven cloth is coated with the rubber agent by an appropriate application means such as a blade coating method.

Then, the surface printing layer-forming rubber paste comprising the above mixture is applied to the surface of the support layer through the primer layer and dried to form the surface printing layer. And
The obtained laminated body is heated and pressed at a predetermined pressure and temperature to be vulcanized to obtain the offset blanket 1 having the compressive layer 5 in the support layer 2. The compressive layer 5 is obtained by applying a rubber paste in which a water-soluble powder such as salt is dissolved to at least one intermediate cloth, drying and vulcanizing it, and then applying 6 to 6 to 10 to 100 ° C. hot water. It is formed by immersing for 10 hours, eluting the water-soluble powder and drying.

The obtained offset blanket 1 is used by being adhered to the peripheral surface of the cylinder of the transfer cylinder either directly or through an undercoating material.

[0015]

【Example】

Examples 1 to 5 and Comparative Example The offset blanket shown in FIG. 1 was prepared under the following conditions. (1) Support Layer 2 A cotton cloth was used as a base cloth, and four pieces of acrylonitrile-butadiene rubber impregnated with the cloth to a thickness of 0.08 mm were laminated. However, the rubber material impregnated in the middle one of the base cloths was prepared by the leaching method using salt as the water-soluble powder.

(2) Surface-printed layer 3 A rubber composition shown in Table 1 was prepared, dissolved in methyl ethyl ketone, and coated on the support layer 4 (unvulcanized) so as to have a coating thickness of 0.30 mm. Dried. The amount of plasticizer added was changed for each formulation to adjust the hardness.

[0017]

[Table 1]

(3) Vulcanization / molding After the surface printing layer was laminated, it was vulcanized and molded at a pressure of 1 kg / cm ² and a temperature of 150 ° C. After vulcanization, the surface of the surface printing layer had a 10-point average roughness (Rz) (JIS B 0601-1982) of 3 to 6
Each offset blanket was obtained by polishing to a thickness of μm. The resulting offset blanket (thickness 1.9
0mm) is actually an offset printing machine (56 made by Ryobi)
Makizuke the transfer cylinder cylinder of type-0) only, printing was carried out in co-chromatography preparative paper. The printing conditions are as follows.

Printing speed: 10,000 sheets / hour Ink: “Mark V New” manufactured by Toyo Ink Co., Ltd. Coated paper: “Utrillo Coat 110 kg” manufactured by Daio Paper Co., Ltd. Evaluation of printability and paper discharge property is performed as follows. I went. (1) Halftone dot shape The halftone dot shape was evaluated by the shape factor of the printed halftone dots. The shape factor of a halftone dot is represented by the following formula, and the closer the shape factor is to 1, the better (closer to a perfect circle). In the following formula, the area and the perimeter are obtained by image analysis.

[0020]

[Equation 1]

(2) Solid Inking Property The density distribution in the solid part was examined by image analysis, and the standard deviation was determined to evaluate the solid inking property. That is,
The smaller the standard deviation, the better. (3) Slur (flow of halftone dots) If the paper ejection performance is poor, so-called "flow" occurs in the printing direction. This flow was evaluated by determining the vertical and horizontal line width ratio (horizontal line width / vertical line width) with a slur gauge. The closer the line width ratio is to 1, the better. (4) Paper discharge property The curl height was measured when 10 sheets of coated paper printed with the full solid were stacked. The lower the curl height, the better the paper discharge property. (5) Paper dust remaining property This is a visual evaluation of the amount of paper dust adhering to the surface of the offset blanket after printing 100,000 sheets.

The evaluation was performed according to the following criteria. ◯: Almost no paper dust is attached. Δ: Paper dust accumulates near the edge. X: Paper dust is attached to the entire surface Table 2 shows the results of these tests.

[0023]

[Table 2]

As is clear from Table 2, in the comparative examples containing no polysulfide rubber, the halftone dot shape and the sticking property are good, but the paper discharging property and the paper dust remaining property are poor. On the other hand, in Examples 1 to 5, the paper discharging property and the paper dust remaining property are improved. However, the more polysulfide rubber is added, the more the halftone dot shape and the solid inking property tend to be deteriorated (Examples 4 and 5). As shown in Examples 1 to 3, it is particularly preferable that the amount of polysulfide rubber added is about 5 to 15 parts by weight based on the total amount of rubber.

[0025]

As described above, according to the offset blanket of the present invention, it is possible to improve the paper discharge property and reduce the remaining paper dust without impairing the print quality and increasing the number of steps. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of an offset blanket of the present invention.

[Explanation of symbols]

 1 Offset Blanket 2 Support Layer 3 Surface Printing Layer 4a Base Fabric 4b Base Fabric 5 Compressible Layer

Claims (1)

(57) [Claims] 1. An offset blanket for printing comprising a support layer and a surface printing layer laminated on the support layer, wherein the surface printing layer comprises an oil resistant rubber and a polysulfide rubber in a weight ratio.
An offset blanket for printing, which is a layer comprising a mixture mixed at 95: 5 to 60:40.