JPH0659748B2 - Offset blanket - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an offset blanket used for offset printing, and more specifically, it has good plate holding, does not cause a bulge phenomenon, and enables good printing. Regarding the offset blanket.

<Prior Art> Conventionally, an offset printing method as shown in FIG. 2 has been generally used as a printing method for obtaining a high quality character image. In the figure, (40) is a plate cylinder rotatably driven by a power source (not shown), and two ink supply roller groups (30), (30) are provided on the upper peripheral surface of the plate cylinder (40) and a lower peripheral surface. A water roller group (31) is arranged on the surface so that it can be driven, and the plate cylinder (4
By driving 0), ink and water are supplied to the plate cylinder (40). Further, a blanket cylinder (2) having an offset blanket (1) wound around the lower end peripheral surface of the plate cylinder (40), and an offset blanket (1) again.
An impression cylinder (50) is arranged in contact with the lower end peripheral surface of each of them, and both are adapted to rotate following the drive of the plate cylinder (40).

When the plate cylinder (40) is driven in the printing machine of the above type, the printing ink is transferred from the ink supply roller groups (30) and (30) to the original pattern drawn on the plate cylinder (40). Is
The original picture pattern is formed on the peripheral surface of the plate cylinder (40). next,
The original pattern is transferred to the offset blanket (1), and the transferred pattern is continuously fed between the offset blanket (1) and the impression cylinder (50), such as a printing medium (printing paper or the like). By being transferred to P), the original pattern on the plate cylinder 40 is printed.

Also, a paper offset printing method as shown in FIG. 3 has been adopted. In the figure, members with the same reference numerals are the same or substantially the same members as the members in FIG.

The outline of this printing method will be described with reference to the figure. As shown in the figure, the continuous paper (Q) fed between the blankets (100) (100) is made of metal through a plurality of guide rollers. Impression cylinder
While being wound around (50), it is pressed by a plurality of offset blankets (1) arranged around the impression cylinder (50),
When (50) is driven, the continuous paper (Q) is fed while being pulled, and printing is performed with each original pattern drawn on the plate cylinder (40) ... Transferred onto it.

By the way, as an offset blanket used for the offset printing as described above, one having a JIS (A) hardness of 50 to 60 ° and a thickness of 0.25 to 0.50 mm is conventionally used.
Was used.

<Problems to be Solved by the Invention> However, with a conventional blanket having a JIS hardness of 50 to 60 °, printing durability, that is, plate holding is not good. That is, when the printing machine is in operation, a strong pressing force and a shearing force are exerted between the plate cylinder and the surface printing layer in contact with the plate cylinder, and the photosensitive resin film corresponding to the pattern portion formed as a convex portion on the plate cylinder. There was a problem that it was easily scraped off. In particular, when using so-called paper plates that have been widely used recently (for example, "Pink Master" (trade name, manufactured by Mitsubishi Paper Mills Ltd.), "Silver Master" (trade name, manufactured by Mitsubishi Paper Mills Ltd., etc.), It was pointed out that the plate life would be extremely poor.

Further, as shown in the explanatory view of FIG. 4, the offset blanket (1) which is rotated in accordance with the rotation of the plate cylinder (40) has the contact of the blanket cylinder (2) with the offset blanket (1). Since the pressing force (J) along the radial direction and the shearing force (F) along the tangential direction of the blanket cylinder (2) are received from the plate cylinder (40), the surface printing layer made of a soft material comes into contact. There is a "bulge phenomenon" in which it rises immediately after passing through the section,
In the case of the conventional offset blanket having a thickness of 0.25 to 0.50 mm, this phenomenon appears to be large and causes distortion that cannot be ignored.

This is because the relative displacement due to the shearing force between the upper and lower layers of the surface printing layer appears in proportion to the thickness, so in the case of a conventional offset blanket with a large thickness, not to mention when a large shearing force is applied, This is because distortion that cannot be ignored is generated even if a large shearing force is not applied.

The present invention has been made in view of the above circumstances, and an object thereof is to specify an hardness and a thickness of a surface printing layer to provide a good offset and an offset blanket with a small image distortion due to a bulge phenomenon. To provide.

<Means for Solving the Problems> In order to achieve the above object, the offset blanket according to the present invention has hardness and thickness smaller than those of conventional products.

That is, the offset blanket according to the present invention has a support layer having a smooth surface, JIS hardness of 20 to 50 °, a thickness of 0.01 to 0.20 mm, and a thickness with respect to the entire thickness. It is characterized in that a surface printing layer of 10% or less is laminated.

Here, the support layer directly bonded to the surface printing layer is made of a material that has a smooth surface and does not hinder the smoothness of the surface printing layer in order to secure the smoothness of the surface printing layer and enable printing with less distortion. It needs to be made, and examples of such a material include a finely textured cloth material, a plastic film, and a gold foil.

Further, as the main material of the surface printing layer, an oil resistant elastic body is preferable, and according to the experimental results by the present inventors, a vinyl chloride polymer is particularly preferable, for example, polyvinyl chloride, polyvinyl chloride copolymerization resistance, polyvinylidene chloride, etc. Is mentioned.

When acrylonitrile-butadiene rubber (NBR) which has been conventionally used as a main material is used, it is preferable to use NBR having an acrylonitrile content of 32 to 40%. This is because when the acrylonitrile content exceeds 40%, the swelling due to the solvent becomes small, which is preferable in this sense, but this causes the disadvantage that the rubber elasticity is extremely reduced, and conversely, when the acrylonitrile content is less than 32%. This is because the rubber elasticity is kept good but the swelling resistance is extremely lowered.

<Operation> In the offset blanket according to the present invention having the above-described configuration, the thickness of the surface printing layer is 0.01 to 0.20 mm, and the ratio of the total thickness to the total thickness is 10% or less. The distortion of the surface print layer due to pressure and shear force is small. Further, since the JIS (A) hardness is in the range of 20 to 50 °, printing faithful to the original pattern can be performed without scraping off the photosensitive resin film on the plate cylinder.

<Examples> Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of an offset blanket,
On the back side of the surface rubber layer (11) as a surface printing layer carrying the printing ink transferred from the plate cylinder on the surface, a base fabric layer (as a support layer supporting the surface rubber layer (11) ( 12), compressible layer (13), base cloth layer (14), intermediate rubber layer (15), base cloth layer (16),
The intermediate rubber layer (17) and the base cloth layer (18) are sequentially laminated.

Here, the base cloth layers (12), (14), (16) are made of a cloth material, but the base cloth layer (12) directly bonded to the surface rubber layer (11) is
As described above, in order to ensure the smoothness of the surface rubber layer (11),
Composed of a relatively fine cloth and has a compressible layer
(13) is composed of a foam layer.

Samples 1 to 3 according to the present invention having three specifications having the thicknesses shown in Table 1 having the above-described laminated structure were prepared, and Comparative tests 1 to 3 with the conventional product also shown in the same table. Was done.

Composition of surface printing layer of samples 1 to 3 and conventional product and JIS
(A) Hardness is as follows.

[Specification 1] << Composition >> Polyvinyl chloride (Nippon Zeon Co., Ltd., trade name Zeon 121) ... 100 parts by weight dioctyl phthalate ... 185 parts by weight Dibutyltin laurate stabilizer (Kyodo Chemical Co., Ltd., trade name KS -22) 3 parts by weight 288 parts by weight in total << JIS (A) hardness >> 20 ° [Sample 2] << Composition >> Oil-extended NBR (34% by weight acrylonitrile component, manufactured by Nippon Zeon Co., Ltd., trade name DN-224) ... 150 parts by weight Zinc oxide ... 5.0 parts by weight Stearic acid ... 1.5 parts by weight Hydrous silicic acid ... 30.0 parts by weight Processing aid (Schill & Seilacher, Stractol WB212) ... 5.0 parts by weight Factis ... 20.0 parts by weight Titanium oxide ... 10.0 parts by weight Sulfurization accelerator DM: 1.0 parts by weight Vulcanization accelerator TS: 1.5 parts by weight Sulfur: 1.5 parts by weight Total 225.5 parts by weight << JIS (A) hardness >> 30 ° [Sample 3] << Composition >> Polyvinyl chloride (Nippon Zeon ( ), Trade name Zeon 121) ... 100 parts by weight adipic acid polyester-based plasticizer (manufactured by ADEKA ARGUS, trade name P-200) 150 parts by weight dibutyl tin laurate stabilizer (manufactured by Kyodo Chemical Co., Ltd., trade name KS22 ) 5 parts by weight Polyglycol antifoaming agent (Daiichi Kogyo Seiyaku Co., Ltd., trade name Anti-Fross F) ... 2 parts by weight 257 parts by weight << JIS (A) hardness >> 50 ° [Conventional product] << Composition >> NBR (Nippon Zeon Co., Ltd., trade name Nipo11042) ... 100 parts by weight Zinc oxide ... 5.0 parts by weight Stearic acid ... 1.5 parts by weight Dibutylphthalate ... 10.0 parts by weight Hydrous silicic acid ... 20.0 parts by weight Processing aids (Schill & Seilacher, Strak Tall WB212) ... 5.0 parts by weight Factis ... 20.0 parts by weight Titanium oxide ... 10.0 parts by weight Vulcanization accelerator M ... 1.0 parts by weight Vulcanization accelerator DM ... 1.0 parts by weight sulfur ... 1.5 parts by weight 155.0 parts by weight << JIS (A) Hardness >> 60 ° [Test 1] Under the following test conditions, the dot size at the start of printing is 100%.
As a result, the relationship between the increase in the number of printed sheets and the decrease in the halftone dot diameter was determined for Sample 1 and the conventional product.

(Test conditions) Plate: Mitsubishi Paper Mills, Ltd., Silver Master Test offset blanket: Sample 1 and conventional product Printing machine: Komori Printing Co., Ltd., Lithrone 26 Printing speed: 8000rph Printing pressure: Between plate / offset blanket 0.10mm Offset blanket / 0.15mm between impression cylinders Printing ink: New Bright (red) manufactured by Toyo Ink Co., Ltd. (Test results) Fig. 5 is a graph showing the test results, with the vertical axis of 50% halftone dots. The diameter change rate is shown, and the horizontal axis is the number of printed sheets. As shown in the figure, the number of printed sheets when the diameter change rate of the ink receiving film on the plate is 50% is about 5,000 sheets in the conventional product (shown by the broken line in the figure). , Sample 1
(Indicated by the solid line in the figure) is about 17,000 sheets,
In the case of 75%, the number of prints is about 70 for conventional products.
In comparison with the 00th sheet, the sample 1 had about 26,000 sheets.

From this test result, it is understood that the sample 1 according to the present invention is superior in plate holding by about 3 times as compared with the conventional product.

[Test 2] Under the following test conditions, the dot size at the start of printing is 100%
As a result, the relationship between the increase in the number of printed sheets and the decrease in the dot diameter was determined for Sample 2 and the conventional product.

(Test conditions) Plate: Mitsubishi Paper Mills Ltd., Pink Master Test offset blanket: Sample 2 and conventional printer: Ryobi Ltd., Ryobi 3200CD Printing speed: 6000rph Printing pressure: 0.10mm between plate and offset blanket Offset blanket / pressure cylinder 0.15mm Ink for printing: Dainippon Ink and Caps G (red) (Test result) Fig. 6 is a graph showing the test result, with the vertical axis of 50% halftone dot The diameter change rate is shown, and the horizontal axis is the number of printed sheets. As shown in the figure, when the diameter change rate of the ink receiving film on the plate is 50%, the number of printed sheets is about 500 for the conventional product (shown by the broken line in the figure). , Sample 2
(Shown by the solid line in the figure) is about 1500 sheets, and the number of prints at 75% is about 750 for conventional products.
It was the 2300th sheet in the case of Sample 2 as compared with the 2nd sheet. From the test results, in the case of Sample 2 according to the present invention,
It is understood that the plate life is about three times better than the conventional product.

[Test 3] Sample 3 was tested for the presence or absence of printing defects such as “missing” in resist printing on a printed circuit board under the following test conditions.
Also, the pitch accuracy was obtained while examining the conventional product.

(Test conditions) Plate: Toray Co., Ltd., waterless planographic plate Test offset blanket: Sample 3 and conventional product Printing machine: Shimogaki Co., calibration machine Printing speed: 4000rph Printing pressure: 0.10mm between plate / offset blanket Offset blanket / 0.15mm between impression cylinder Printing ink: Printed material: Copper clad substrate (Test result) In the case of the conventional product, many “dropouts” were observed in the resist part, but in the case of sample 3, it was completely I was not able to admit.
This is because in the conventional product, zinc oxide, hydrous silicic acid, and the like mixed as particles fall off from the surface to form a recess on the surface of the offset blanket.

From this, it is understood that when the sample 3 according to the present invention is used, better resist printing can be performed as compared with the case where the conventional product is used.

Regarding the pitch accuracy, the length of the original plate pattern with a length of 500 mm on the glass substrate (printed material) was 501.004 mm (+1.004 mm) in the conventional product,
In Sample 3, it was 500.050 mm (+0.050 mm). This is because, as described above, when the conventional product is used, the bulge phenomenon largely appears, whereas when the sample 3 according to the present invention is used, since the thickness is small, the bulge phenomenon hardly appears. Is.

From this, it is understood that when the sample 3 according to the present invention is used, it is possible to perform resist printing faithful to the original pattern as compared with the case where the conventional product is used.

<Effects of the Invention> As described above, since the hardness and thickness of the offset blanket according to the present invention are within a certain range, which is smaller than those of conventional ones, the present invention has a good plate holding property. In addition, a very excellent practical effect is achieved such that good printing can be performed without distortion due to the bulge phenomenon.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an offset blanket, FIGS. 2 and 3 are explanatory views of offset printing, FIG. 4 is an explanatory view of a bulging phenomenon, and FIGS. 5 and 6 show test results in Examples. It is a graph. (1)… Offset blanket, (2)… Blanket cylinder, (11)… Surface rubber layer

Claims (1)

[Claims] 1. A support layer having a smooth surface and having a JIS (A) hardness of 20 to 50 ° and a thickness of 0.01 to 0.20 mm and a thickness of 10% or less based on the total thickness. An offset blanket, wherein the surface printing layer is laminated.