JP3451203B2 - Printing blanket - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-shaped printing blanket which is used, for example, by winding it around a blanket cylinder of an offset printing machine.

[0002]

2. Description of the Related Art Generally, a printing blanket has a structure in which a surface printing layer made of an elastomer such as rubber is laminated on at least one base cloth. In addition, recently, in order to respond to the speeding up of printing machines and the high quality of printed images,
A so-called air-type printing blanket in which a porous compressible layer made of an elastomer such as rubber is interposed between the base cloth and the surface printing layer is becoming popular.

The air-type printing blanket has a compressive stress at a nip deforming portion caused by pressure contact with a plate cylinder, etc., as compared with a conventional one having no compressible layer (usually referred to as a solid-type printing blanket). Is low,
Moreover, since the change in the compressive stress due to the change in the strain amount at the nip deforming portion is small, the shock absorbing property is generally good.
Therefore, for example, the impact generated by the feeding of the gears of the printing press or the impact generated when the seam of the blanket wrapped around the blanket cylinder passes through the pressure contact part with the plate cylinder affects the printing accuracy. It is excellent in the effect of preventing.

Further, in the solid type printing blanket, so-called bulge occurs due to stress concentration on the surface printing layer at the nip deformation portion, and misregistration due to the elongation of the surface printing layer in the circumferential direction, paper feeding failure, and duplication. However, there is a possibility that printing defects such as deformation of the halftone dot pattern (especially thick halftone dots) may occur. On the other hand, in the air type printing blanket, the compressive layer alleviates the stress concentration on the surface printing layer and suppresses the expansion of the surface printing layer in the circumferential direction. It also has the effect of preventing the occurrence.

Examples of the above-mentioned compressible layer include (a) foaming of a matrix rubber with a foaming agent that decomposes by heating to generate a gas, or (b) compounding of hollow fine particles into the matrix rubber. After the vulcanization of the matrix rubber in which the individual pores are independent and the pores are independent of each other, and (c) the matrix rubber in which particles such as sodium chloride are dispersed is vulcanized, water (in the case of salt, water) is used. There is a continuous pore structure in which the respective pores communicate with each other, which is formed by a so-called leaching method for extracting the above particles.

[0006]

However, in any of the above cases, forming the compressive layer requires many complicated steps as described above, and the size of the pore structure to be formed, etc. Is likely to vary,
The air type printing blanket having such a compressible layer has a problem that the productivity is lower than that of the solid type.

An object of the present invention is to improve productivity because it has a simpler structure than an air type printing blanket, and yet to have a new compression property similar to that of an air type printing blanket. To provide a printing blanket.

[0008]

The printing blanket of the present invention for solving the above-mentioned problems substantially comprises a surface printing layer and at least one base cloth, Among the above-mentioned base cloths, at least one piece of the base cloths is partially or entirely formed of hollow fibers.

The term "substantially composed of a surface printing layer and a base cloth" as used herein means that the printing blanket of the present invention is similar to the conventional solid type without a compressible layer. It means having a structure, for example, vulcanizability for adhering between the base fabric and the surface printing layer, or for adhering the base fabrics when two or more base fabrics are laminated. It does not preclude the use of auxiliary components, such as rubber-containing adhesives (so-called vulcanized adhesives).

Further, in the printing blanket of the present invention, the cavities in the hollow fibers constituting a part or the whole of the base fabric act in the same manner as the pores of the conventional compressible layer, so that they are compressed as described above. The functional layer can be omitted. Therefore, the printing blanket of the present invention has excellent productivity because it has the same laminated structure as that of the solid type printing blanket, which is simpler than that of the air type printing blanket. It will have the same excellent compression properties as a blanket.

Further, by devising the structure of the base cloth and obtaining the compression characteristic equivalent to that of the air type printing blanket while omitting the compressive layer, for example, Japanese Patent Publication No. 62- Japanese Patent No. 55519 discloses a printing blanket in which a three-dimensional fabric woven from weft yarns and warp yarns and vertical yarns extending perpendicularly to the orientation direction of these yarns is used as a base fabric.

However, although the above-mentioned printing blanket has good compression characteristics at the initial stage of use, as is clear from the results of Examples and Comparative Examples described later, it is less durable than that of the present invention. This is sufficient, and when printing is performed continuously, the bending deformation of the vertical yarn remains as a permanent strain due to repeated compression, so that so-called "sagging" occurs, and there is a problem that the compression characteristics greatly fluctuate (deteriorate). .

Further, in claim 1 of Japanese Unexamined Patent Publication No. 6-297877, a high-strength chemical fiber cut into about 10 to 30 cm high-strength fiber cotton and a mixed-spun yarn or a mixture of short-fiber cotton up to about 5 cm. There is disclosed a printing blanket in which a layered and configured structure using twisted yarn is used as a base fabric. However, since such a base fabric is basically not considered to have the function of the compressible layer, a printing blanket using such a base fabric has the following examples,
As is clear from the results of the comparative example, although the durability at the time of repetition is good, it has already been used from the initial stage of its use.
There is a problem that the compression characteristics as good as those of the printing blanket of the present invention cannot be obtained.

Further, claim 2 of JP-A-6-297877 discloses that the above-mentioned base fabric and the above-mentioned three-dimensional fabric are combined to improve the compression characteristics of the printing blanket. In this case, the structure becomes complicated, and the durability of the printing blanket becomes insufficient like the one described in the above publication, and the compression characteristics largely fluctuate (deteriorate) when continuously printed. There is a problem.

Further, the hollow fiber used in the present invention, as described above, has its own cavities that act like the pores of the conventional compressible layer, so that the base fabric containing the hollow fiber is plain weave or the like. A woven fabric having a simple woven structure or a non-woven fabric having a simple and easily manufactured structure can be adopted. On the other hand, the three-dimensional woven fabrics used in both of the above publications must be produced by using a special special loom, which causes a problem of low productivity.

Therefore, in any of the configurations disclosed in these publications, it is not possible to obtain the same excellent operational effects as the printing blanket of the present invention.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings showing an example of an embodiment thereof. First, the examples of FIGS. 1A and 1B and FIG. 2 will be described.
The printing blanket 1 of this example has a five-layer structure in which a surface printing layer 12 is laminated on four base fabrics 11a, 11b ... As shown in FIG. As shown in 2, the whole is formed in a sheet shape.

Of the above, the details of the four base fabrics 11a, 11b, ... Include in order from the top in the drawing, a base fabric (normal base fabric) 11a composed only of non-hollow ordinary fibers, and hollow fibers. The base cloth 11b, the normal base cloth 11a, and the normal base cloth 11a. Of the above, base fabric 11b containing hollow fibers
For example, as shown in FIG. 1 (b), the warp yarn Wr
A woven fabric produced by weaving, that is, knitting or weaving, a yarn in which hollow fibers HF are twisted together in at least one (and both in the case of the figure) of the weft Wf is preferably used. .

The warp yarn Wr and the weft yarn Wf used in the example of the figure are both formed by twisting a plurality of hollow fibers HF.
Single fibrous hollow fibers may be used. In addition, the hollow fiber H is provided in one or both of the warp yarn Wr and the weft yarn Wf.
It is also possible to use a mixture of F and ordinary fibers that are not hollow.

The above woven fabric uses hollow fibers HF for both the warp threads Wr and the weft threads Wf, as shown in the figure, by changing the size and the twist number of the hollow fibers HF forming the warp threads Wr and / or the weft threads Wf. There is an advantage that the compression characteristic of the printing blanket 1 can be finely adjusted and the compression characteristic can be made substantially uniform over the entire surface of the printing blanket 1 by changing only one of them.

Although the woven structure of the base cloth 11b is not particularly limited, in consideration of the ease of manufacturing the base cloth 11b as described above, a so-called plain weave or twill weave in which warps Wr and wefts Wf are alternately crossed one by one, It is preferable to adopt a basic and simple woven structure such as satin weave. Base cloth 11
As the b, a so-called non-woven fabric or the like, which is produced by randomly arranging or entangled hollow fibers with a means such as an adhesive or heat and pressure, can also be used.

In order to greatly change the compression characteristics of the printing blanket 1, the number of base fabrics 11b containing hollow fibers may be changed as shown in FIGS. 3 (a) to 3 (c), for example. Of these, the printing blanket 1 of FIG. 3 (a) includes two intermediate fabrics out of four fabrics and a fabric 11b containing hollow fibers.
The upper and lower two sheets are the normal base cloth 11a. Further, in the printing blanket 1 of FIG. 3 (b), the lower three of the four base fabrics are the base fabrics 11b containing hollow fibers, and only the uppermost one is the normal base fabric 11a. It is a thing. Further, in FIG. 3C, all of the four base fabrics are base fabrics 11b containing hollow fibers.

As described above, as the number of the base fabrics 11b containing hollow fibers is increased, the compressive stress with respect to the strain amount becomes lower and the compressive stress due to the change of the strain amount becomes smaller, as is clear from the results of Examples described later. Since the fluctuation can be reduced, the shock absorbing property of the printing blanket 1 is further improved. When the number of the base fabrics 11b containing hollow fibers is 5 or more, the compressive stress becomes too low, which may reduce the ink inking property, and the number of times the base fabrics are attached increases. There is also a possibility that productivity will decrease. Therefore, the number of the base fabrics 11b containing the hollow fibers is preferably about 1 to 4.

The total thickness of the base fabric 11b containing the hollow fibers (thickness of itself in the case of one sheet) is not particularly limited, but is preferably about 0.1 to 1.5 mm. When the total thickness of the base fabric 11b is less than the above range,
The compression characteristics of the printing blanket may deteriorate.

On the other hand, if the total thickness exceeds the above range, the compressive stress becomes too low, and the ink receptivity may deteriorate. In addition, the total thickness of the base fabric 11b containing the hollow fibers is 0.5 in the above range.
~ 1.5 mm is preferred, 0.5-1.3 mm
Is more preferable.

Hollow fibers HF contained in the base fabric 11b
As, various conventionally known chemical fibers having cavities inside, that is, regenerated fibers, semi-synthetic fibers and synthetic fibers,
Both can be used. For example, in the case of the figure, the external cross section is circular, and there is only one at the center,
Hollow fibers, which are also provided with cavities of circular cross section continuously along the length direction, have the advantage that the stress characteristics against compression are equalized. , And the cross-sectional shape of the cavity are
It may have various shapes other than the circular shape. Further, the number of cavities in the hollow fiber is not limited to one, and two or more cavities may be formed in parallel with each other. Furthermore, the cavities may be intermittent rather than continuous.

Examples of the polymer constituting the hollow fiber include polyester, rayon, nylon and aromatic polyamide. The size of the hollow fiber is not particularly limited and may be appropriately set depending on the number of twists and the like, but normally, the outer diameter is about 10 to 50 μm and only one is formed in the center of the hollow fiber as described above. In the case of the formed cavity, the inner diameter is preferably about 5 to 30 μm.

Specific examples of such hollow fibers are not limited to these. For example, JP-A-53-35028, JP-A-54-50620, and JP-A-57-61.
No. 717, Japanese Patent Application Laid-Open No. 63-175110, Japanese Patent Application Laid-Open No. 3-90613 and the like, or a product name “New Sup” manufactured by Toyobo Co., Ltd.,
Product name "RX 21" also made by Toyobo Co., Ltd., triangular hollow fiber for carpet made by Toyobo Co., Ltd., triangular hollow fiber for carpet made by Asahi Kasei Corp., carpet made by Asahi Kasei Corp. Square hollow fibers and the like can be mentioned. The ordinary base cloth 11a and the surface printing layer 12 which form the printing blanket 1 together with the base cloth 11b containing the hollow fibers can have the same configurations as in the related art.

For example, as the usual base cloth 11a, cotton,
Woven or non-woven fabric such as polyester or rayon is used. The thickness of the base cloth 11a may be the same as the conventional one, that is, about 0.2 to 0.6 mm. The surface printing layer 12
Is an unvulcanized rubber layer formed by applying and drying a rubber paste prepared for the surface printing layer, or an unvulcanized rubber layer formed into a sheet from a rubber compound for the surface printing layer. It is formed by vulcanization.

As the rubber constituting the surface printing layer 12,
For example, acrylonitrile-butadiene copolymer rubber (N
BR, chloroprene rubber (CR), urethane rubber (U), and other oil-resistant rubbers that have resistance to ink and cleaning liquid are preferably used, as well as polysulfide rubber (T) and hydrogenated NBR. You can also do it.
The thickness of the surface printing layer 12 is about the same as the conventional one, that is, 0.2
It is preferably about 0.6 mm.

Printing blanket 1 having the above layers
The above-mentioned base cloths 11a and 11b are laminated via the above-mentioned vulcanizing adhesive, specifically, in the state where the vulcanizing adhesive is glued onto the base cloth, and the vulcanizing adhesive is also vulcanized on the base cloth. Via an adhesive, or directly, pressurize a laminate in which an unvulcanized rubber layer that is a base of the above-mentioned surface printing layer is laminated,
It is manufactured by heating to vulcanize the vulcanizing adhesive and the rubber layer.

The vulcanization may be carried out each time the above layers are laminated, but vulcanization of all the layers at once is
It is suitable in terms of productivity. In addition, the surface printing layer 12 and the vulcanizing adhesive among the above layers are both described above.
From the viewpoint of simplifying the process and improving the productivity of the printing blanket by eliminating variations, it is non-foaming.

The produced sheet-shaped printing blanket 1 is wound around the blanket cylinder of an offset printing machine, for example, directly or through an underlay material, and is adhered to the blanket cylinder axis of the offset printing machine. Used by being extrapolated. As the rubber constituting the vulcanizing adhesive, oil-resistant rubbers such as NBR, CR, and U described above are preferably used in consideration of resistance to ink and the like as in the surface printing layer.

Various additives can be added to the vulcanizing adhesive, or the rubber compound and the rubber paste which form the surface printing layer 12, as in the conventional case. Examples of such additives include vulcanizing agents, vulcanization accelerators, vulcanization accelerating aids, agents for vulcanizing rubber such as vulcanization retarders, as well as antiaging agents, reinforcing agents, fillers, softening agents. Agents and plasticizers. The amount of these additives to be added may be similar to the conventional amount.

Among the above, examples of the vulcanizing agent include sulfur, organic sulfur-containing compounds, organic peroxides, and the like.
Of these, organic sulfur-containing compounds include, for example, N, N '.
-Dithiobismorpholine and the like, and examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide and the like. Examples of the vulcanization accelerator include thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide and tetramethylthiuram monosulfide; zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, sodium dimethyldithiocarbamate, diethyl. Dithiocarbamic acids such as tellurium dithiocarbamate; Thiazoles such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfenamide; trimethylthiourea;
Examples thereof include organic accelerators such as thioureas such as N, N′-diethylthiourea, and inorganic accelerators such as slaked lime, magnesium oxide, titanium oxide and litharge (PbO).

Examples of the vulcanization accelerator include metal oxides such as zinc white, and fatty acids such as stearic acid, oleic acid and cottonseed fatty acid. Examples of the vulcanization retarder include aromatic organic acids such as salicylic acid, phthalic anhydride and benzoic acid; N-nitrosodiphenylamine, N-nitroso-2,2,4-trimethyl-1,2.
Examples include nitroso compounds such as -dihydroquinone and N-nitrosophenyl-β-naphthylamine.

Examples of the antiaging agent include imidazoles such as 2-mercaptobenzimidazole; phenyl-α-naphthylamine, N, N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl. Examples thereof include amines such as -p-phenylenediamine; phenols such as di-t-butyl-p-cresol and styrenated phenol.

Carbon black is mainly used as a reinforcing agent, as well as an inorganic reinforcing agent such as silica-based or silicate-based white carbon, zinc white, surface-treated precipitated calcium carbonate, magnesium carbonate, talc and clay. Alternatively, an organic reinforcing agent such as coumarone indene resin, phenol resin, high styrene resin (styrene-butadiene copolymer having a high styrene content) can be used.

Examples of the filler include inorganic fillers such as calcium carbonate, clay, barium sulfate, diatomaceous earth, mica, asbestos and graphite, regenerated rubber, powder rubber, asphalt, styrene resin,
Examples include organic fillers such as glue. Examples of the softener include various vegetable oil-based, mineral oil-based, and synthetic softeners such as fatty acids (stearic acid, lauric acid, etc.), cottonseed oil, tall oil, asphalt substances, and paraffin wax.

Examples of the plasticizer include various plasticizers such as dibutyl phthalate, dioctyl phthalate and tricresyl phosphate. In addition to the above, the rubber may be blended with, for example, a tackifier, a dispersant, a solvent and the like as appropriate. The configuration of the printing blanket of the present invention is not limited to the example shown in the drawings described above, and various design changes can be made without departing from the scope of the present invention.

For example, the number of base fabrics is not limited to four, and if at least one base fabric 11b containing hollow fibers is included therein, the total number of fabrics is three or less, but five or more. May be When the number of sheets is 5 or more, it is preferable that the number of the base fabrics 11b containing hollow fibers is 4 or less for the reason described above. For example, FIGS. 4 (a) and (b) and FIGS. 5 (a) and 5 (b) are examples in which the number of base fabrics constituting the non-stretchable layer is 5, respectively.

In FIG. 4 (a), of the five base fabrics, the second one from the top is the base fabric 11b containing hollow fibers,
The other four sheets are the normal base cloth 11a. In addition, FIG. 4 (b) shows the second and third sheets from the top among the five base cloths.
One sheet is a base cloth 11b containing hollow fibers, and the other three sheets are normal base cloths 11a. Furthermore, FIG.
The middle three of the base fabrics are the base fabrics 11 containing hollow fibers.
b, and the upper and lower two sheets are the normal base cloth 11a. And FIG. 5 (b) shows the lower 4 of the 5 base fabrics.
The sheet is a base fabric 11b containing hollow fibers, and only the uppermost one is a normal base fabric 11a.

In addition, the arrangement and configuration of each layer constituting the printing blanket 1 can be appropriately changed. In short, in the sheet-shaped printing blanket, other constitutions are not particularly limited as long as hollow fibers are contained in the base cloth instead of omitting the conventional compressible layer.

[0044]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. Example 1 Hollow fiber made of polyester having an outer diameter cross section of a circular shape and only one center hole at the center thereof having a circular shape of a circular cross section continuously formed [outer diameter 20 μm, inner diameter of the cavity] 10
.mu.m, New Sup made by Toyobo Co., Ltd.], 3 warp yarns and 15 weft yarns were plain woven to a thickness of 0.
A 4 mm base fabric was prepared.

Next, one of the above-mentioned base cloth and three pieces of cotton cloth having a thickness of 0.3 mm as a normal base cloth are laminated by gluing NBR-based vulcanizing adhesives, respectively, and then, the uppermost base cloth is laminated. A rubber paste for the surface printing layer, which is also NBR type, was glued onto the cloth and dried. Then, the whole laminate is vulcanized by pressurizing and heating with a vulcanizer, and then the surface of the surface printing layer is polished to have a laminated structure shown in FIG. The thickness of the printed layer is 0.4 mm, the total thickness is 1.7 mm, and the number of the base fabrics woven by the hollow fibers is one as described above,
A sheet-shaped printing blanket having a total thickness of 0.4 mm was manufactured.

Example 2 Two base fabrics, which are the same as those produced in the above-mentioned Example 1, and which are entirely woven with hollow fibers, and a thickness of 0.3 as a normal base fabric.
The same procedure as in Example 1 was repeated except that two mm mm cotton cloths were laminated with NBR-based vulcanizing adhesive.
It has the laminated structure shown in FIG. 3 (a), the thickness of the surface printing layer is 0.4 mm, the total thickness is 1.8 mm, and the number of base fabrics woven with hollow fibers is 2 as described above. A sheet-shaped printing blanket having a total thickness of 0.8 mm was manufactured.

Example 3 Three base fabrics, the same as those produced in the above-mentioned Example 1, entirely woven with hollow fibers, and a thickness of 0.3 as a normal base fabric.
The same procedure as in Example 1 was repeated except that 1 mm mm cotton cloth was laminated with NBR-based vulcanizing adhesive.
It has the laminated structure shown in FIG. 3 (b), the thickness of the surface printing layer is 0.4 mm, the total thickness is 1.9 mm, and the number of base fabrics woven with hollow fibers is 3 as described above, A sheet-shaped printing blanket having a total thickness of 1.2 mm was manufactured.

Comparative Example 1 Each of the four base fabrics was a normal base fabric and had a thickness of 0.3 m.
Sheet-like printing having a conventional solid type structure and a surface printing layer having a thickness of 0.4 mm and a total thickness of 1.6 mm, in the same manner as in Example 1 except that a cotton cloth of m is used. Blanket was manufactured.

Comparative Example 2 Three cotton cloths each having a thickness of 0.3 mm as an ordinary base cloth were laminated by gluing NBR-based vulcanizing adhesives on each other, and then NBR was also applied on the uppermost base cloth. System, and a rubber paste for a compressible layer in which salt particles (particle diameter 1 to 100 μm) were mixed was glued and dried.

Then, this laminate is pressurized and heated to be vulcanized, and then leaching treatment is performed by immersing it in hot water at 70 ° C. for 6 hours to extract salt particles, and dried to have a continuous pore structure. A compressible layer having a thickness of 0.3 mm was formed. Next, on the compressible layer of this laminate, one NBR-based vulcanizing adhesive is glued, and one cotton cloth having a thickness of 0.3 mm is laminated as a normal base cloth as described above. Same as NB
An R-based vulcanizing adhesive and an NBR-based rubber paste for the surface printing layer were applied in this order and dried.

Then, the entire laminated body is vulcanized by pressurizing and heating with a vulcanizing can, and then the surface of the surface printing layer is polished to have a conventional air type structure and a surface. A sheet-shaped printing blanket having a print layer thickness of 0.4 mm and a total thickness of 1.9 mm was produced. Comparative Example 3 In order to reproduce the printing blanket disclosed in Japanese Patent Publication No. 62-55519, a non-hollow ordinary polyester fiber yarn (60 count) was used for warp yarns, weft yarns and vertical yarns, and A 1.5 mm three-dimensional fabric was woven.

Next, one piece of this three-dimensional woven fabric was used as a base fabric, on which NBR-based vulcanizing adhesive and the same NBR were used.
After gluing the rubber glue for the surface printing layer, which is the system, in this order and drying, pressurize and heat the whole with a vulcanizer to vulcanize, and then polish the surface of the surface printing layer. Then, a sheet-like printing blanket having a two-layer structure shown in FIG. 5 of the above publication and having a surface printing layer thickness of 0.4 mm and a total thickness of 1.9 mm was produced.

Comparative Example 4 In order to reproduce the printing blanket disclosed in claim 1 of JP-A-6-297877, aramid fiber (trade name Kevlar manufactured by DuPont) as a high-strength chemical fiber is 10 to 30 cm. A high-tensile fiber cut to a certain extent and a short fiber obtained by cutting the same fiber into 5 cm or less were mixed-spun yarn (60 count) was used for the warp and weft, and the thickness was 0.4.
mm plain weave base fabric was woven. And this base cloth,
A sheet form in which the thickness of the surface printing layer is 0.4 mm and the total thickness is 1.7 mm, in the same manner as in Example 1 except that the whole base fabric is woven with hollow fibers. Blanket for printing was manufactured.

The following tests were carried out on the printing blankets produced in the above Examples and Comparative Examples to evaluate their characteristics. Compression Property Test (Initial) As shown in FIG. 6, the center of the unused printing blanket 1 immediately after being manufactured in each of the Examples and Comparative Examples is a cross-sectional half as a model of a blanket cylinder of an offset printing machine. Along the surface of the circular mounting body 2, and with its both ends pulled by a constant pulling force in the direction indicated by the white arrow in the drawing, the mounting body 2 is moved to the black position in the drawing using the piston 3. Move it in the direction indicated by the arrow and press the impression cylinder 4 as a model of the plate cylinder.
The initial compressive stress (kgf) generated according to the amount of strain (mm) in the thickness direction when the printing blanket 1 was distorted by being pressed against was measured.

Compression Characteristic Test (After Repeated Compression) The printing blankets of each Example and Comparative Example were wound around a blanket cylinder, adhered, and extrapolated to the blanket cylinder shaft of an offset printing machine (Model 560 manufactured by Ryobi Co., Ltd.). Along with
The plate cylinder was rotated 5 million times at a rotation speed of 500 rpm in a state where the printing blanket was pressed so as to receive a compressive strain of 0.15 mm, and then the compressive stress after repeated compression ( kgf) was measured.

The initial result is shown in FIG. 7 (a), and the result after repeated compression is shown in FIG. 7 (b). As is apparent from these figures, both the conventional solid type printing blanket of Comparative Example 1 and the printing blanket of Comparative Example 4 corresponding to claim 1 of JP-A-6-297877 are used. From the initial stage, it has been found that the compressive characteristics are not good because the compressive stress with respect to the strain amount is high and the change of the compressive stress with the change of the strain amount is large.

Further, the printing blanket of Comparative Example 3 corresponding to that of Japanese Patent Publication No. 62-55519 has a change in strain amount in the initial stage of use as compared with the printing blanket of Comparative Example 2 which is a conventional air type. It was found that the fluctuation of the compressive stress due to the change was small and the compressive property was good, but the compressive property was deteriorated due to the larger settling in the thickness direction than that of other printing blankets due to the repeated compression.

On the other hand, all of the printing blankets of Examples 1 to 3 have the same simple structure as that of Comparative Example 1 which is a solid type, but the Comparative Example 1
Alternatively, it was found that the compressive stress with respect to the strain amount was lower than that of Comparative Example 4 and the fluctuation of the compressive stress due to the change of the strain amount could be reduced. It was also found that the printing blankets of each of the examples had excellent durability because the compression characteristics did not significantly change due to repeated compression and no significant settling or the like occurred in the appearance.

Comparing the results of each of the above Examples, the greater the number of base fabrics woven with hollow fibers, the better the compression characteristics. Particularly, the printing blanket of Example 3 is an air type Comparative Example. It was confirmed to have the same compression characteristics as those of No. 2. Furthermore, the printing blankets of Examples 2 and 3 have a strain amount of 0.15 m corresponding to the thickness of normal paper.
As shown in FIG. 7 (a) and Table 1 below, the initial compressive stress at m is within the ideal range of 60 to 150 kgf, and the compressive stress at the same strain amount after repeated compression is also As shown in FIG. 7 (b) and Table 1 below, since the above range was maintained, it was found that good printing equivalent to that of the air type Comparative Example 2 was possible.

[0060]

[Table 1] Example 4 A hollow acrylic fiber having an outer diameter cross section of which is circular, and only one hollow fiber having a circular cross section is formed in the center thereof continuously along the length direction [outer diameter 50 μm, inner diameter of cavity]. 20μ
m, manufactured by Toyobo Co., Ltd. RX21] was double woven as a double twist for both warp and weft to prepare a base fabric having a thickness of 0.1 mm.

Then, in the same manner as in Example 1 except that one piece of this base cloth and four pieces of cotton cloth having a thickness of 0.3 mm as an ordinary base cloth were laminated by gluing, as shown in FIG. It has the laminated structure shown, and the thickness of the surface printing layer is 0.4 mm, the total thickness is 1.7 mm, and the number of base fabrics woven with hollow fibers is 1
A sheet-shaped printing blanket having a total thickness of 0.1 mm was manufactured.

Example 5 A hollow fiber having an outer diameter of 50 μm, which was the same as that used in Example 4 above, was plain woven with six warps and wefts to prepare a base fabric having a thickness of 0.3 mm. In addition, a hollow fiber made of polyester in which the outer diameter cross section is circular and only one center hole is continuously formed along the length direction to have a circular cross section [outer diameter 30 μm, hollow inner diameter 20 μm] The Toyo Boseki Co., Ltd. New Sup] was plain woven with 6 warps and wefts as a 6-twist to produce a base fabric having a thickness of 0.2 mm.

Then, the same procedure as in Example 1 was carried out except that one of each of these two kinds of base cloth and three pieces of cotton cloth having a thickness of 0.3 mm as a normal base cloth were laminated by gluing. It has the laminated structure shown in FIG. 4 (b), and the thickness of the surface printing layer is 0.4 mm, the total thickness is 1.8 mm, the number of base fabrics woven by hollow fibers is 2, and the total thickness is Is 0.5
A sheet-like printing blanket having a size of mm was produced.

Example 6 The same hollow fiber having an outer diameter of 50 μm as that used in the above Example 5 was plain woven with 6 warps and 6 wefts. As in Example 1, except that two cotton cloths having a thickness of 0.3 mm were laminated by gluing, and the surface printing layer had a thickness of 0. 0.4 mm, total thickness 1.
A sheet-shaped printing blanket having a thickness of 9 mm and a total number of base fabrics woven by hollow fibers of 3 and a total thickness of 0.9 mm was manufactured.

Example 7 A hollow fiber having an outer diameter of 50 μm, which was the same as that used in Example 4 above, was plain woven with 8 warps and wefts to prepare a base fabric having a thickness of 0.4 mm. Then, 1 piece of this base cloth, 3 pieces of base cloth having a thickness of 0.3 mm obtained by plain weaving hollow fibers having an outer diameter of 50 μm, which are the same as those used in Example 5, with 6 warps and 6 wefts, and an ordinary base cloth are used. A laminated structure shown in FIG. 5 (b) is obtained in the same manner as in Example 1 except that one piece of cotton cloth having a thickness of 0.3 mm is glued and laminated, and the thickness of the surface printing layer is 0.4mm, total thickness 2.0mm, the number of base fabric woven by hollow fibers is 4
A sheet-shaped printing blanket having a total thickness of 1.3 mm was manufactured.

Example 8 In Example 7, the same hollow fiber having an outer diameter of 50 μm as that used in Example 5 was plain woven with 6 warps and 6 wefts. Same as Example 1 except that the same hollow fiber having an outer diameter of 50 μm was used and three warp and weft yarns were plain woven and three 0.4 mm-thick base fabrics were laminated by gluing. And has a laminated structure shown in FIG. 3 (c), the surface printing layer has a thickness of 0.4 mm, the total thickness is 1.9 mm, and the total number of base fabrics woven with hollow fibers is four, which is the total. Thickness is 1.5
A sheet-like printing blanket having a size of mm was produced.

With respect to the printing blanket manufactured in each of the above-mentioned examples, both of the above-mentioned tests were conducted to evaluate its characteristics. The measurement result of the compressive stress after the initial compression and after the repeated compression at a strain amount of 0.15 mm corresponding to the thickness of normal paper is shown by the total thickness Th (m
Table 2 below together with m).

[0068]

[Table 2] From the above table, the total thickness Th (m
It was confirmed that the larger m) is, the lower the compressive stress in the initial and repeated compressions is.

Particularly, in the printing blankets of Examples 6 to 8, the initial compressive stress was 60 to 150 kg as described above.
Since the compression stress within the range of f and the compression stress after repeated compression are also maintained within this range, it was found that good printing equivalent to that of the air type of Comparative Example 2 was possible.

[0070]

As described above in detail, according to the present invention, since it has a laminated structure which is simpler than that of the air type and substantially the same as that of the solid type, it has excellent productivity. Moreover, it has a unique effect of providing a printing blanket having excellent compression characteristics similar to those of the air type.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a printing blanket of the present invention, in which FIG. 1 (a) is a partially enlarged cross-sectional view, and FIG. 1 (b) shows warp yarns and weft yarns containing hollow fibers as essential parts. It is an expanded sectional view of the base fabric woven by the method.

FIG. 2 is a perspective view showing an entire printing blanket of the above example.

3A to 3C are partially enlarged cross-sectional views showing another example of the printing blanket of the present invention.

4A and 4B are partially enlarged cross-sectional views showing another example of the printing blanket of the present invention.

5 (a) and 5 (b) are partially enlarged sectional views showing still another example of the printing blanket of the present invention.

FIG. 6 is a front view of an apparatus for measuring compression characteristics of printing blankets manufactured in Examples and Comparative Examples.

FIG. 7 is a graph showing the compression characteristics of the printing blankets manufactured in Examples and Comparative Examples, that is, the relationship between the amount of strain and the compression stress.

[Explanation of symbols]

1 printing blanket 11a, 11b base cloth 12 Surface printing layer HF hollow fiber

Front Page Continuation (72) Inventor Keimichi Sagawa 1 41 Shimizu, Uozumi-cho, Akashi-shi, Hyogo Sumitomo Rubber Fish Dormitory (56) References JP 63-249696 (JP, A) JP 62-282986 (JP) JP, A) JP 58-65049 (JP, A) JP 6-297877 (JP, A) JP 6-219078 (JP, A) JP 1-141035 (JP, A) Sho 61-25168 (JP, U) Actual development Sho 52-99801 (JP, U) Japanese Patent Sho 62-55519 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41N 10 / 04

Claims (6)

(57) [Claims] 1. A sheet-like printing blanket substantially comprising a surface printing layer and at least one base cloth, wherein at least one base cloth is part of the base cloth. Or, a blanket for printing, characterized in that it is entirely composed of hollow fibers. 2. The printing blanket according to claim 1, wherein the base fabric is a woven fabric in which hollow fibers are used for at least one of warp and weft. 3. The printing blanket according to claim 2, wherein at least one of the warp and the weft is formed by twisting a plurality of hollow fibers. 4. Adhesion comprising two or more base fabrics, each of which comprises a base fabric partially or wholly formed of hollow fibers, wherein each base fabric comprises a vulcanizable rubber. The printing blanket according to claim 1, wherein the printing blanket is laminated and adhered via an agent. 5. The printing blanket according to claim 4, wherein the surface printing layer and the base cloth are laminated and adhered via an adhesive containing a vulcanizable rubber. 6. The number of base cloths partially or wholly composed of hollow fibers contained in a plurality of base cloths is 1 to 4,
The printing blanket according to claim 4, which has a total thickness of 0.1 to 1.5 mm.