JP3023907B2 - Blanket for offset printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a blanket for offset printing used in an offset printing machine.

[0002]

2. Description of the Related Art In offset printing, an image from a printing plate is once transferred to a blanket, and the image transferred to the blanket is printed on paper. An offset printing press basically includes a plate cylinder, a blanket cylinder, and an impression cylinder. The printing plate mounted on the plate cylinder has a printing plate with water that requires the supply of dampening water to the non-image portion, and no water that does not require the supply of dampening water to the non-image portion. There are two types of printing plates. In the printing method using these two types of printing plates,
Since the management and adjustment of dampening water is not required in the waterless printing method, the waterless printing method has gradually spread in recent years.

However, the waterless printing method, compared to the waterless printing method, has printing plate durability, reproducibility of halftone dots (thickness of halftone dots), ease of separation of the printing paper from the blanket, ie, blanket separation. It is said to be inferior in properties (paper separation). In particular, in recent years, as the speeding up of printing has progressed, there has been a strong demand for improvements in blanket separation (paper separation). The printing method with water will be described. A general printing unit includes, as shown in FIG. 2, an inking device 5 for supplying ink to a plate cylinder 3 on which a printing plate 1 is mounted, and a water supply device for supplying dampening water. The printing cylinder 11 is basically provided with a blanket cylinder 10 mounted with a blanket 9 which rotates in conjunction with the plate cylinder 3 and an impression cylinder 13 which presses and holds the printing paper 11 against the blanket cylinder 10. It is configured. When using this, first, the printing plate 1 is supplied with dampening water from the water supply device 7, then the ink is supplied from the inking device 5, and the ink image on the plate is transferred to the blanket 9, and this image is transferred to the blanket 9. Is impression cylinder 13
Is printed on the printing paper 11 passing between the two.

[0004]

The function of the dampening solution is to protect the non-image areas on the plate and prevent ink from adhering to the non-image areas. The fountain solution supplied to the plate mainly reaches the ink fountain for supplying the ink via the ink roller, and the others are consumed by being transferred to the blanket. Therefore, if the supply amount of dampening water is increased in order to improve the blanket separation property (paper separation property), the amount of dampening water reaching the ink fountain from the plate via the ink roller increases.
The ink will be over-emulsified. If the ink is excessively emulsified, the transfer of the ink from the ink roller to the plate is inhibited, which affects print quality. To prevent this, it is necessary to reduce the supply amount of dampening water as much as possible and to protect the non-image area with a thin water film.

In both the waterless printing method and the waterless printing method, with the recent deterioration of printing paper quality and the increase in printing speed, the blanket surface in contact with the non-image portion of the blanket or the edge portion of the printing paper has been developed. However, there is a problem that paper powder detached from the paper, a coating agent on the surface of the printing paper, and the like accumulate, thereby deteriorating the blanket releasability (paper releasability). That is, as shown in FIG. 3, fine powder 14 such as paper dust or a coating agent of the printing paper is deposited around the edge 12 of the printing paper on the surface of the blanket 9, and the quality of the blanket surface is changed (change in ink transferability). ) And dents in the blanket in the stacking area. Regarding the accumulation of paper dust and the like, comparing the printing method without water and the printing method with water,
It is said that the printing method with water is slightly better. As described above, the accumulation of paper dust and the like affects the blanket separation property. In particular, improvement of blanket separation property (paper separation property) is required in high-speed printing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to improve the blanket separation property (paper separation property) by modifying at least the uppermost layer of the surface rubber layer so that no paper dust is deposited. The present invention provides a blanket for offset printing which is excellent in (1).

[0007]

The present invention has the following configuration to achieve the above object. That is, the offset printing blanket according to claim 1 of the present invention is an offset printing blanket comprising a support composed of at least one sheet and a surface rubber layer laminated on the support. At least the uppermost layer is formed of rubber mixed with far-infrared radiation ceramics. The blanket for offset printing according to claim 2 is characterized in that the far-infrared ceramics is blended in an amount of 5 parts by weight or more. Further, in the blanket for offset printing according to claim 3, the far-infrared ceramics has a wavelength of 3 to 500 μm, and is room temperature or 100 ° C.
It is a far-infrared ceramic radiating at the following temperatures.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A blanket according to the present invention
If it is a compressible blanket, it does not matter whether it is an incompressible blanket. For example, as shown in FIG. 1, rubber paste is applied to a cotton cloth and laminated in two layers to form a support body 15, After the compressible layer 17 is formed thereon, an oil-resistant surface rubber layer 20 is further laminated on the compressible layer 17 via a support 19 made of cotton cloth. 21 has a structure formed of rubber mixed with far-infrared ceramics. The support 15 and the support 19 can be made of a known woven cloth such as rayon cloth or polyester cloth in addition to cotton cloth. Vulcanizing agents such as sulfur, vulcanization accelerators,
One or more kinds of anti-aging agents and the like are added and used.

Although there are several factors that affect the blanket separation (paper separation), focusing on the difference in blanket separation between the waterless printing method and the water printing method, the difference between the inks depending on the printing method. Although some effects were observed, it was also found that the presence or absence of dampening solution on the blanket was significantly involved. Also, far infrared,
In particular, it is known that when ceramics that emit far-infrared rays having a wavelength of 3 to 500 μm are brought into contact with water, the form of clusters of water molecules changes. Therefore, if the morphology of the clusters changes, far-infrared ceramics will be applied to the blanket surface rubber layer based on the idea that even the slightest dampening solution may protect the non-image area of the blanket and improve the blanket separation. It is blended.

The blanket in which far-infrared ceramics is blended in the surface rubber layer has improved blanket releasability and significantly reduced paper dust accumulation, as will be apparent from the examples described later. The entire surface rubber layer 20 may be formed of rubber containing far-infrared ceramics, but at least the uppermost layer portion 21 that contacts the printing paper is formed of rubber containing far-infrared ceramics. The far-infrared ceramic preferably emits far-infrared light having a wavelength of 3 to 500 μm and emits at room temperature or at a temperature of 100 ° C. or lower in consideration of the use condition of the blanket. Such ceramics include, for example, Al ₂ O ₃ , Mn
Metal oxides such as O ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ and ZrO ₂ , metal nitrides such as Si ₃ N ₄ , metal carbides such as SiC, titanates such as aluminum titanate, and mixtures thereof. No.

The amount of the far-infrared ceramic is not particularly limited, but is preferably 5 parts by weight or more in practical use. In this way, when far-infrared ceramics are blended in the surface rubber layer, the far-infrared ceramics change the form of the clusters to protect the non-image area even with a small amount of fountain solution and improve blanket separation. Prevent the accumulation of paper dust. By reducing the supply amount of the dampening solution, the amount of dampening solution reaching the ink fountain from the plate via the ink roller is also reduced, so that the ink is not excessively emulsified.

[0012]

EXAMPLES Examples of the present invention will be described below together with comparative examples. The configuration of the blanket in the following Examples and Comparative Examples was a compressible blanket with normal surface polishing. The composition of the surface rubber layer is as shown in Tables 1 and 2.

[0014]

[Table 1]

[0015]

[Table 2]

The printing conditions for the paper dust test are as follows. The printing paper used was Shin-Oji Paper's Kanto Art 76.5 Kg, and the plate was a printing plate with water, and Konica's KM3 (product number) was used. The printing speed was 10,000 sheets / hour. The test pattern was a chromai system, the ink was Hi-Echo (indigo) manufactured by Toyo Ink, and the dampening solution was a 3% aqueous solution of SG51 manufactured by Tokyo Ink. In the evaluation method of the paper dust test, the printing press was stopped every predetermined number of prints, and the accumulation state of the paper dust at a portion (edge portion) where the edge of the paper was in contact with the blanket was examined.

Next, the printing conditions of the paper separation test were such that the test pattern was all solid, and the other conditions were the same as the printing conditions of the paper dust test. The evaluation method of the paper separation test was to measure the curl height (curl height) on the butt end side of the paper after printing 1,000 sheets.

Table 3 shows the results of the state of accumulation of the paper dust on the blanket at the portion in contact with the edge of the paper in the paper dust test. It can be seen that the addition of far-infrared ceramics suppresses the accumulation of paper powder. Although an effect can be obtained with a small amount of addition, it is preferable to add 5 parts by weight or more in practical use.

[0019]

[Table 3]

As shown in Tables 4 and 5, the results of the paper separation test show that the addition of far-infrared ceramic lowers the curl height on the butt end side of the paper and reduces the blanket separation (paper separation). ) Is improved. Also in this paper separation test, it is practically preferable to add 5 parts by weight or more.

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

In the blanket for offset printing according to the present invention, at least the uppermost layer of the surface rubber layer is formed of rubber compounded with far-infrared ceramics. The accumulation of paper dust and the like is prevented. Further, since the supply amount of the dampening solution can be reduced, the amount of the dampening solution reaching the ink fountain via the ink roller is also reduced, so that excessive emulsification of the ink can be prevented and the print quality can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing an example of a blanket according to the present invention.

FIG. 2 is an explanatory diagram of a printing unit in the offset printing press.

FIG. 3 is an explanatory diagram showing a state of accumulation of paper powder on a blanket.

[Explanation of symbols]

 Reference Signs List 1 printing plate 3 plate cylinder 5 inking device 7 water supply device 9 blanket 10 blanket cylinder 11 printing paper 12 edge portion of printing paper on blanket surface 13 impression cylinder 14 fine powder such as coating agent of printing paper 15 support 17 compressible layer 19 Support 20 Surface Rubber Layer 21 Uppermost Layer of Surface Rubber Layer

Claims (3)

(57) [Claims] 1. An offset printing blanket comprising a support comprising at least one sheet and a surface rubber layer laminated on the support, wherein at least the uppermost layer of the surface rubber layer is made of a far-infrared radiation ceramic. A blanket for offset printing characterized by being formed of compounded rubber. 2. The blanket for offset printing according to claim 1, wherein the far-infrared ceramic is blended in an amount of 5 parts by weight or more. 3. The method according to claim 2, wherein the far-infrared ceramic is 3 to 50.
3. The blanket for offset printing according to claim 1, wherein the blanket is a far-infrared ceramic having a wavelength of 0 [mu] m and radiating at a normal temperature or a temperature of 100 [deg.] C. or less.