JPH03126595A - Offset blanket - Google Patents

Abstract

PURPOSE:To make resistance, processability, permanent strain characteristics and printing characteristics excellent with respect to both of oily ink and ultraviolet curable ink by constituting the raw material rubber constituting a surface printing layer of medium/high nitrile rubber and ultrahigh nitrile rubber respectively having specific Mooney viscosities. CONSTITUTION:A surface printing layer 3 is formed to the surface of a support layer 1 through a compressive layer 2 composed of synthetic resin foam. The raw material rubber constituting the surface printing layer 3 is composed of medium/high nitrile rubber having Mooney viscosity of 75 ML1+4 (100 deg.C) or more and ultrahigh nitrile rubber having Mooney viscosity of 45 ML1+4 (100 deg.C) or more. A plurality of base cloths 11 are laminated through primer layers (adhesive layers) G to constitute the support layer 1 and the surface printing layer 3 is formed on the support layer 1 through the primer layers G. The thickness of the surface printing layer 3 is pref. 350mum or less.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an offset blanket used in offset printing.

<Prior art and problems to be solved by the invention> Conventionally, general oil-based ink (oxidation polymerization type) has been used for the above-mentioned offset printing, but recently, heat curing type, ultraviolet curing type, and electron beam curing type have been used. A variety of printing inks are used, including ultraviolet curing inks, which are cheaper and more economically advantageous than conventional oil-based inks, especially from the viewpoint of environmental hygiene and because they cause less set-off when stacked. It is increasingly being used in combination with

The surface printing layer of the offset blanket, which uses general oil-based ink, uses nitrile rubber that is resistant to the oil-based ink and the cleaning oil used at the end of work, when changing patterns, etc. The above nitrile rubber has five grades, from low nitrile to extremely high nitrile, depending on the acrylonitrile content, and low nitrile rubber (acrylonitrile content 18-24%) is
Although it has excellent processability, permanent deformation properties, and printing properties (ink transfer properties), it has insufficient oil resistance.On the contrary, extremely high nitrile rubber (acrylonitrile content 43-50%) has excellent oil resistance, but Processability, permanent deformation properties, and printing properties tend to be poor. For this reason, the surface printing layer is generally made of medium nitrile rubber (
(acrylonitrile content 25-30%) or medium-high nitrile rubber (acrylonitrile content 31-35%) are used.

On the other hand, in UV-curable inks, the acrylic monomer contained in the ingredients causes the medium to medium high nitrile rubber to swell, so
Offset blankets are used that have a surface printing layer made of a nonpolar rubber material such as ethylene propylene diene rubber (EPDM) or ethylene propylene rubber (EPM), which has excellent resistance to acrylic monomers.

However, as mentioned above, although the non-polar rubber material has better resistance to acrylic monomers than nitrile rubber, it does not have complete resistance and will still swell when used repeatedly. Moreover, the non-polar rubber material mentioned above has significantly inferior oil resistance compared to nitrile rubber, so general oil-based inks and cleaning oils cannot be used with it. Therefore, UV-curable inks and oil-based inks are used in combination. When doing so, there is a problem in that each time the ink is changed, the offset blanket must be replaced with one for each ink.

This invention was made in view of the above circumstances, and provides an offset blanket that has excellent resistance to both oil-based inks and ultraviolet curing inks, as well as excellent workability, permanent deformation characteristics, printing characteristics, etc. is intended to provide.

Means and operation for solving the above problems> The offset blanket of the present invention for solving the above problems has the following features:
The raw rubber constituting the surface printing layer has a Mooney viscosity of 75M.
Medium-high nitrile rubber with a temperature of L1.4 (100°C) or higher,
It is characterized by being made of extremely high nitrile rubber with a Mooney viscosity of 45ML++4 (100°C) or higher.

In the offset blanket of the present invention having the above structure, the medium-high nitrile rubber has excellent processability, permanent set characteristics, printing characteristics, etc., and the extremely high nitrile rubber is compatible with oil-based inks and ultraviolet curing type inks. Since it has excellent resistance to both, the above-mentioned surface printing layer using both of these rubbers as raw materials has all of the above-mentioned characteristics.

Mooney viscosity cuff 5MLI+4 of the above medium-high nitrile rubber
(100°C) or more is limited to the Mooney viscosity of medium-high nitrile rubber in an unvulcanized state of 75ML+.

If the temperature is less than 4 (100° C.), sufficient resistance to oil-based inks and ultraviolet curing inks cannot be obtained. Note that the Mooney viscosity of the medium-high nitrile rubber is preferably 100 ML10a (100°C) or more.

On the other hand, the Mooney viscosity of extremely high nitrile rubber is 45MLI+
4 (100°C) or above is limited if the Mooney viscosity of the ultra-high nitrile rubber in the unvulcanized state is 45ML1
This is because if the temperature is less than +4 (100°C), sufficient permanent set characteristics and workability cannot be obtained. Incidentally, the Mooney viscosity of the above-mentioned extremely high nitrile rubber is 50 MLl. 4 (100℃
) or more is preferable.

The blending ratio of the medium-high nitrile rubber and the extra-high nitrile rubber is preferably within the range of 10:90 to 50:50 in terms of weight ratio.

In the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber, if the blending ratio of extra-high nitrile rubber is less than 50% by weight, sufficient resistance to oil-based inks and ultraviolet curing type inks will not be obtained. Conversely, if the blending ratio of the extremely high nitrile rubber exceeds 90% by weight, there is a risk that printing properties, permanent deformation properties, and processability may not be sufficiently obtained. be.

The blending ratio of the medium-high nitrile rubber and the extra-high nitrile rubber is preferably in the range of 20:8.0 to 40:60 by weight.

The surface printing layer uses the above-mentioned medium-high nitrile rubber and extra-high nitrile rubber as raw material rubber, and mixes various additives such as a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerating aid, and a filler with this raw material rubber. It is formed by molding the compounded rubber into the shape of a surface printing layer and then vulcanizing it by a conventional method.

Examples of the vulcanizing agent contained in the compounded rubber include tetramethylthiuram disulfide (TMTD), N,
Examples include organic sulfur-containing compounds such as N'-dithiobismorpholine, sulfur, and the like.

In addition, as a vulcanization accelerator, dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N-oxydiethylene-2-benzothiazyl sulfenamide (OB S
), N-tart-butyl-2-benzothiazylsulfenamide (TBBS) and other thiazoles are mentioned as main promoters, and if necessary, 1,3-diphenylguanidine (DPG), tetramethylthiuram mono sulfide (TMTM), zinc dimethyldithiocarbamate (ZnMDC), zinc ethylphenyldithiocarbamate (ZnEPDC), and tetramethylthiuram disulfide (TMTD) mentioned under the vulcanizing agent.
etc. can also be appropriately blended as a secondary accelerator.

Examples of fillers include inorganic fillers such as calcium carbonate, hard flexible soft clay, barium sulfate, diatomaceous earth, talc, mica, asbestos, graphite, and pumice; recycled rubber;
Examples include organic fillers such as powdered rubber, asphalts, styrene resin, and glue.

The offset blanket of the present invention provided with the above surface printing layer is formed, for example, into the layer structure shown in FIG. 1 (al(b)).

FIG. 1 shows the structure of a compressible offset blanket in which a surface printing layer 3 is formed on the surface of a support layer 1 via a compressible layer 2 made of synthetic resin foam or the like.

In addition, in FIG.
This shows a typical offset blanket configuration in which the two are directly laminated.

In addition, in the offset blanket shown in both figures above,
The support layer 1 is constructed by laminating multiple layers (three layers in the figure) of the base fabric 11 through a primer layer (adhesive layer) G. A surface printing layer 3 is formed thereon with a primer layer G interposed therebetween. Although the thickness of the surface printing layer 3 in the offset blankets shown in both figures is not particularly limited, it is preferably 350 μm or less.

In addition, in order to prevent the surface printing layer 3 from shifting due to the pressure applied during printing and printing defects such as misalignment of halftone dots and poor registration, the compression A base fabric 11 is also interposed between the layer 2 and the surface printing layer 3 via the primer layers G, G.

The layer structure of the offset blanket of this invention is as follows:
The structure is not limited to those shown in the above two figures, and various conventionally known layer structures can be adopted.

<Example> The present invention will be explained below based on Examples.

Example 1 Acrylonitrile content 34%, Mooney viscosity 140M
L, 30 parts by weight of medium-high nitrile rubber (manufactured by Polycer, trade name Flynac PK34-140) at 100°C, acrylonitrile content 50%, Mooney viscosity 75
ML+, 4 (100°C) raw material rubber mixed with 70 parts by weight of ultra-high nitrile rubber (manufactured by Polycer, trade name Flynac PK50-75), 3 parts by weight of zinc oxide,
A compounded rubber was prepared by blending 1.5 parts by weight of sulfur, 1 part by weight of stearic acid, 40 parts by weight of hard clay, and 0.7 parts by weight of N-tert-butyl-2-benzothiazylsulfenamide (TBBS). Manufactured. In addition, the acrylonitrile content of the raw material rubber is 0.34X30+0.50X
It was 70-45.2%.

Next, the raw material rubber is laminated via the adhesive on the surface of the support layer manufactured by laminating three cotton base fabrics via a rubber adhesive as a brimer, and then processed. A surface printing layer with a thickness of 350 μm was formed by sulfurization, as shown in Fig. 1(b).
An offset blanket with the layer structure shown in was manufactured.

Example 2 An offset blanket was manufactured in the same manner as in Example 1, except that the amount of medium-high nitrile rubber in the raw rubber was 25 parts by weight, and the amount of extra-high nitrile rubber was 75 parts by weight. The acrylonitrile content of the raw material rubber is 0.34x25+0.50x75-46.
It was 0%.

Example 3 An offset blanket was manufactured in the same manner as in Example 1, except that the amount of medium-high nitrile rubber blended in the raw rubber was 35 parts by weight, and the amount of extra-high nitrile rubber blended was 65 parts by weight. In addition, the acriparonitrile content of the above raw material rubber is 0.34x35+0.50x65-44
．． It was 4%.

Example 4 Acrylonitrile content 34%, Mooney viscosity 75ML
++4 (100°C) 35 parts by weight of medium-high nitrile rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name N231H), acrylonitrile content 44%, Mooney viscosity 45ML++4
(100℃) extremely high nitrile rubber (manufactured by Japan Synthetic Rubber Co., Ltd.,
An offset blanket was produced in the same manner as in Example 1 above, except that a raw rubber obtained by mixing 65 parts by weight of N222L (trade name) was used. The acrylonitrile content of the raw material rubber was 0.34X35+〇, 44X65-40.5%.

Comparative Example 1 Raw material rubber had an acrylonitrile content of 30% and a Mooney viscosity of 29ML. An offset blanket was produced in the same manner as in Example 1, except that 100 parts by weight of medium nitrile rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name N24IH) was used.

Comparative Example 2 As a raw material rubber, a medium-high nitrile rubber with an acrylonitrile content of 34% and a Mooney viscosity of 140 ML++4 (100°C) (manufactured by Borisar, trade name Flynac PK34)
-140) An offset blanket was manufactured in the same manner as in Example 1 above, except that 100 parts by weight was used.

Comparative Example 3 Raw material rubber had an acrylonitrile content of 44% and a Mooney viscosity of 45 ML. An offset blanket was produced in the same manner as in Example 1 above, except that 100 parts by weight of ultra-high nitrile rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name N222L) of 4 (100° C.) was used.

Comparative Example 4 As a raw rubber, an extremely high nitrile rubber with an acrylonitrile content of 45% and a Mooney viscosity of 47 ML1-a (100°C) (manufactured by UGINE KUHLMANN, product name B) was used.
An offset blanket was manufactured in the same manner as in Example 1 above, except that 100 parts by weight of T-405) was used.

Comparative Example 5 Raw material rubber had an acrylonitrile content of 50% and a Mooney viscosity of ? 5 M L 1+4 (100℃) extra-high nitrile rubber (manufactured by Borisar, trade name: Flynac PK5)
0-75) An offset blanket was manufactured in the same manner as in Example 1 above, except that 100 parts by weight was used.

Comparative Example 6 Acrylonitrile content 34%, Mooney viscosity 70ML
++4 (100°C) 35 parts by weight of medium-high nitrile rubber (manufactured by Borisar, trade name Flynac 833), acrylonitrile content 48%, Mooney viscosity 45ML++
An offset blanket was prepared in the same manner as in Example 1, except that a raw material rubber made by mixing 65 parts by weight of ultra-high nitrile rubber (manufactured by Japan Synthetic Rubber Co., Ltd., trade name N2155L) at 4 (100°C) was used. Manufactured. The acrylonitrile content of the raw material rubber was 0.34x35+0.48x65-43.1%.

Comparative Example 7 Ethylene φ propylene diene rubber (
An offset blanket was manufactured in the same manner as in Example 1 above, except that 100 parts by weight of Nisblane (trade name, manufactured by Sumitomo Chemical Co., Ltd.) was used.

Oil resistance test The compounded rubber used in each of the above examples and comparative examples was molded and vulcanized to produce a block of l+nm x 2 cm x 2 (1), and this block was immersed in toluene kept at 40 ° C. The volume after 24 hours was measured, and from the volume VTI before immersion and the volume V72 after immersion, the following formula (1) was calculated.
Based on this, the volume increase rate ΔVT (%) due to swelling was calculated.

A block of the same size as that used in the oil resistance test above was
Acrylic monomer (MAND) kept at 40℃
A) Measure the volume after 24 hours, and from the volume VMI before immersion and the volume vM2 after immersion, calculate the volume increase rate ΔVM (%) due to swelling based on the following formula (I[)
was calculated.

The compounded rubber used in each of the above examples and comparative examples was molded and vulcanized to a thickness of 12.70±0.13 mm and a diameter of 29 mm.
．． A 0no1 right cylindrical test piece was prepared and JIS K
6301, a compression set test was conducted to calculate the compression set rate CS (%).

Printing property test The offset blankets of the above examples and comparative examples were loaded into an ink transfer tester (manufactured by PrLifbau), and black ink (manufactured by Toyo Ink Co., Ltd., Toyo Ink Mark V) was applied.
was used to print on coated paper (manufactured by Mitsubishi Paper Mills) under the following conditions, and the ink transfer rate T+ (%) from the original plate to the offset blanket and the ink transfer rate T2 (%) from the offset blanket to the paper were calculated. Calculated.

·Test condition Mark Pressure...60ON Printing speed...4 m/s Roll temperature...25℃ Supply ink amount...0.522 Room temperature...25℃ Humidity degree...60% The above results are shown in Table 1.

(Left below) From the results of the oil resistance test and acrylic monomer resistance test shown in Table 1 above, the surface printing layer in the offset blankets of Comparative Examples 1 and 2, which were formed from medium to medium high nitrile rubber alone, and the ethylene and The surface printing layer of the offset blanket of Comparative Example 7, which was formed of propylene diene rubber, had low oil resistance and acrylic monomer resistance, and swelled significantly after 24 hours of immersion. In addition, as in the examples, the offset blanket of Comparative Example 6 used a combination of a medium-high nitrile rubber and an extremely high nitrile rubber, but the Mooney viscosity of the medium-high nitrile rubber was less than 75 ML, 4 (100°C). also,
It had low oil resistance and acrylic monomer resistance, and swelled significantly after 24 hours of immersion. On the other hand, the surface printing layers in the offset blankets of Examples 1 to 4 had oil resistance and acrylic resistance to the same extent as the surface printing layers in the offset blankets of Comparative Examples 3 to 5, which were formed solely from ultra-high nitrile rubber. It was found that it has excellent monomer properties.

In addition, from the results of the compression set property test, the surface printing layers in Comparative Examples 3 to 5 and the surface printing layer in Comparative Example 6 formed of extremely high nitrile rubber alone had a compression set rate CS ( %) was large, and it was greatly deformed by pressurization. On the other hand, the surface printing layers in Examples 1 to 4 were formed of medium to medium high nitrile rubber alone, and the surface printing layers in Comparative Examples 1 and 2 were formed of ethylene-bu, propylene-diene rubber. The compression set ratio CS (%) was as small as that of the surface printing layer in Example 7, and after pressurization, the material could be restored to its original shape. From this, it was found that the offset blankets of Examples 1 to 4 described above had excellent compression set characteristics.

From the results of the printing property test, it was found that the offset blankets of Comparative Examples 3 to 5, in which the surface printing layer was formed solely of ultra-high nitrile rubber, and the offset blanket of Comparative Example 6, were ink-free from the original plate. Metastasis rate T+(
%), and the ink transfer rate T2 (%) to paper is low.
It was not possible to print clearly. In addition, the offset blanket of Comparative Example 2, in which the surface printing layer was formed of medium-high nitrile rubber alone, and the offset blanket of Comparative Example 7, in which the surface printing layer was formed of ethylene-propylene diene rubber, were different from those of Comparative Examples 3 to 6 above. However, the ink transfer rate T1 (%) from the original plate and the ink transfer rate T2 (%) to paper were low, and clear printing could not be performed. On the other hand, the offset blankets of Examples 1 to 4 all have an ink transfer rate TrC% from the original plate and an ink transfer rate T2 (%) to paper.
Both were as high as the offset blanket of Comparative Example 1, which was formed from medium nitrile rubber alone, and from this, it was found that the offset blankets of Examples 1 to 4 had excellent printing characteristics.

Contains acrylonitrile, It34%, Mooney viscosity 14
0ML,. 4 (100°C) medium-high nitrile rubber (manufactured by Polycer, trade name Flynac PK34-140),
Acrylonitrile content 50%, Muny viscosity 75ML,
. 4 (100°C) ultra-high nitrile rubber (manufactured by Borisar, trade name Flynac PK50-75) was heated at 10:90 to 90:10 as shown in Figure 2 (aJ to (d)).
To 100 parts by weight of raw rubber mixed in 9 different blending ratios, 3 parts by weight of zinc oxide, 1.5 parts by weight of sulfur, 1 part by weight of stearic acid, 40 parts by weight of hard clay, N -tert-
Butyl-2-penzothiazylsulfenamide (TBB
S) 0.7 parts by weight was blended to produce nine types of compounded rubber.

Next, using a compounded rubber using only 100 parts by weight of medium-high nitrile rubber, a compounded rubber using 100 parts by weight only of extremely high nitrile rubber, and the above nine types of compounded rubber,
The aforementioned oil resistance test, acrylic monomer resistance test, compression set property test, and printing property test were conducted. The results of the oil resistance test are shown in Figure 2 (Fig. 2 tb), the results of the acrylic monomer resistance test are shown in Figure 2 (C), the results of the compression set property test are shown in Figure 2 (C), and the results of the printing property test are shown in Figure 2. Figure (width, each indicated by a solid line).

From the results shown in the figures above, when the blending ratio of medium-high nitrile rubber and very high nitrile rubber is less than 50% by weight, oil resistance and acrylic monomer resistance deteriorate; In the blending ratio of both,
When the blending ratio of the extremely high nitrile rubber exceeded 90% by weight, the printing characteristics and permanent deformation characteristics deteriorated. From this,
In the offset blanket of the present invention, it has been found that the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber is preferably within the range of 10:90 to 50:50 in terms of weight ratio.

The content (%) of acrylonitrile in each of the above blending ratios (weight ratio) is as shown in Table 2 below. (Margins below) Table 2 Also, acrylonitrile content 34%, Mooney viscosity 7
0ML+, 4 (100°C) 35 parts by weight of medium-high nitrile rubber (manufactured by Polycer, trade name Talaitic 833), acrylonitrile content 50%, Mooney viscosity 45M
Using extremely high nitrile rubber (manufactured by Nippon Gosei Rubber Co., Ltd., trade name N2155L) of Ll+4 (100°C), 11 types of compounded rubber were created in the same manner as above, and using this compounded rubber, oil-resistant Tests, acrylic monomer resistance test, compression set property test and printing property test were conducted. As a result, as shown by the broken line in each of the above figures, the Mooney viscosity shown by the solid line was 140ML++4 (
100℃) and medium-high nitrile rubber with a Mooney viscosity of 75.
It was found that the results were worse than the system in which a very high nitrile rubber of ML1+4 (100° C.) was used in combination.

Practical Test 1 The offset blankets of Example 1 and Comparative Examples 2 and 5 were loaded into a metal printing machine (Fuji Kikai Co., Ltd., Brimex), and ultraviolet curing type metal ink (Dainippon Ink Chemical Co., Ltd., Using Daicure (trade name), we printed on the surface of a metal plate, observed the printing on the surface of the finished metal plate, and evaluated how many plates could be used, with 20,000 to 30,000 sheets being one plate. .

Practical Test 2 The same procedure as Practical Test 1 above was used, except that an oil-based ink for metals (manufactured by Toyo Ink Co., Ltd., product name mark ■) was used instead of an ultraviolet curing type ink for metals. evaluated.

The above results are shown in Table 3.

Table 3 From the results in Table 3 above, the offset blanket of Example 1 has excellent resistance to both UV-curable ink and oil-based ink, and can be used in combination with UV-curable ink and oil-based ink. There was found.

<Effects of the Invention> The offset blanket of the present invention is constructed as described above, and the surface printing layer has excellent workability, permanent deformation characteristics, printing characteristics, etc., and is compatible with both oil-based ink and ultraviolet curing type ink. Because it has excellent resistance to
This is suitable for printing using the above-mentioned ultraviolet curing type ink and oil-based ink in combination.

[Brief explanation of the drawing]

Fig. 1 (ω is a schematic sectional view showing an example of the layer structure of the offset blanket of the present invention, first appearance) is a schematic sectional view showing another example of the layer structure, and Fig. 2 (ω is a schematic cross-sectional view showing an example of the layer structure of the offset blanket of the present invention. A graph showing the relationship between the blending ratio of rubber and extra-high nitrile rubber and oil resistance (in Figure 2) is a graph showing the relationship between the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber and acrylic monomer resistance. Figure (C) is a graph showing the relationship between the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber and compression set properties, and Figure 2 (d) is a graph showing the relationship between the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber and printing properties. It is a graph showing the relationship. 1... Support layer, 3... Surface printing layer.

Claims (1)

[Claims] 1. In an offset blanket provided with a surface printing layer on a support layer, the raw rubber constituting the surface printing layer is a medium-high nitrile rubber with a Mooney viscosity of 75ML_1_+_4 (100°C) or more, and Mooney Viscosity 45ML_1_
An offset blanket characterized by being made of extremely high nitrile rubber with a temperature of +_4 (100°C) or higher. 2. The offset blanket according to claim 1, wherein the blending ratio of medium-high nitrile rubber and extra-high nitrile rubber is within the range of 10:90 to 50:50 by weight.