JPH1142869A - Under blanket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make manufacture easy in order to have excellent flexibility and a further simple structure by a method wherein in an under blanket of a specific size or over total thickness which is used for an underlay of a printing blanket, a base material layer is formed of one sheet of a base fabric having a thickness of a specific % of the total thickness. SOLUTION: In an under blanket of 0.8 mm or over total thickness which is equipped with a base material layer and a surface rubber layer and used for an underlay of a printing blanket, the base material layer is formed of a base fabric having a thickness of 50% or over of total thickness. The reason for limiting a thickness of the base fabric within such the range is as follows; in under this range, in order to secure total thickness of the under blanket, a thickness of the surface rubber layer must be thickened, a labor is required for a process wherein the surface rubber layer is formed by applying rubber arabic onto the base fabric, and its manufacture becomes not easy. Further, though the upper limit of the thickness of the base fabric is hot especially limited, it is preferably about 70% of total thickness of the under blanket.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an under blanket used as an underlay for a printing blanket during offset printing.

[0002]

2. Description of the Related Art For example, when winding a printing blanket around an outer periphery of a blanket cylinder of an offset printing machine, an underlay of an appropriate thickness is often provided under the blanket. The purpose of this is to increase the thickness of the printing blanket and adjust the printing blanket to have an appropriate hardness so as to obtain an appropriate printing pressure.

As the underlay, paper, plastic film, felt, cork sheet and the like are also used. In particular, similarly to a printing blanket, a so-called under blanket having a structure in which a support layer and a surface rubber layer are laminated is used. It is preferably used. The under blanket is prepared in several thicknesses in accordance with the desired lifting amount.

Among them, the total thickness is about 0.8 mm or more,
For example, a thick under blanket having a nominal thickness of 1.0 mm or the like is made of two or more base cloths having a thickness of about 0.2 to 0.3 mm, similar to those used in a conventional printing blanket. It is often formed by laminating via glue.

[0005]

However, as described above, an under blanket in which two or more base fabrics are laminated is as follows.
It has a multilayer structure in which a vulcanized layer of rubber glue is sandwiched between each base cloth, and in such a multilayer structure, bending and deformation of each base cloth are limited by upper and lower base cloths and vulcanized layers. Because
There was a problem that the under blanket became too hard. In addition, as the number of base fabrics increases, there is a problem in that the more time and effort are required for the manufacture, and the more difficult the manufacture becomes.

It is conceivable to increase the thickness of the surface rubber layer by using only one base cloth. In this case, however, it is troublesome to apply a rubber paste on the base cloth to form the surface rubber layer. There is also a problem that manufacturing is not easy because of the cost. An object of the present invention is to provide an under blanket which is excellent in flexibility and has a simpler structure and is easy to manufacture.

[0007]

Means for Solving the Problems In order to solve the above problems, the inventors have studied the thickness of the base fabric itself. As a result, the thickness used until now, about 0.2 ~
The present inventors have found that only one rather thick base cloth may be used in place of a thin base cloth of about 0.3 mm, and have completed the present invention.

That is, the present invention comprises a support layer and a surface rubber layer, and is used for underlaying a printing blanket.
An under blanket having a total thickness of 0.8 mm or more, wherein the support layer is formed of one base cloth having a thickness of 50% or more of the total thickness.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. As described above, only one base cloth having a thickness of 50% or more of the total thickness of the under blanket is used as the base cloth constituting the support layer. If the thickness of the base fabric is limited to the above range, below this range, the thickness of the surface rubber layer must be increased in order to secure the total thickness of the under blanket, and rubber paste is applied on the base fabric. This is because the process of applying and forming the surface rubber layer is troublesome and costly, and the production is not easy.

The upper limit of the thickness of the base fabric is not particularly limited, but is preferably about 70% of the total thickness of the under blanket. If the thickness of the base cloth exceeds the above range, the thickness of the surface rubber layer is relatively too thin,
There is a possibility that the impact during printing may not be sufficiently absorbed. The thickness of the base fabric is preferably within the above range, particularly preferably about 60% of the total thickness of the under blanket.

[0011] As the above-mentioned base cloth, cotton, polyester,
A woven or non-woven fabric made of various fibers such as rayon can be used. The surface rubber layer constituting the under blanket together with the base cloth is formed by applying a rubber paste onto the base cloth and vulcanizing an unvulcanized rubber layer formed by drying, as in the related art. Alternatively, an unvulcanized rubber sheet made of a rubber compound may be laminated on a base cloth and vulcanized to form a surface rubber layer.

The hardness of the surface rubber layer is not particularly limited, but is preferably about 40 to 80 ° in JIS A hardness. If the hardness of the surface rubber layer is less than the above range, the under blanket may not be given an appropriate hardness for obtaining the above-described appropriate printing pressure, and when the hardness exceeds the above range, There is a possibility that sufficient flexibility cannot be imparted to the under blanket.

The rubber constituting the surface rubber layer is, for example, acrylonitrile-butadiene copolymer rubber (NB
R), chloroprene rubber (CR), urethane rubber (U)
In addition to oil-resistant rubbers having resistance to inks and cleaning liquids, polysulfide rubber (T), hydrogenated NBR, and the like can also be used. In the above rubber,
Various additives can be blended as in the conventional case.

Such additives include, for example, vulcanizing agents,
In addition to vulcanization accelerators, vulcanization accelerators, vulcanization retardants and other agents for vulcanizing rubber, antioxidants, reinforcing agents, fillers, softeners, plasticizers and the like can be mentioned. The amounts of these additives may be the same as in the conventional case. Among the above, examples of the vulcanizing agent include sulfur, organic sulfur-containing compounds, organic peroxides, and the like. Examples of the organic sulfur-containing compound include N, N'-dithiobismorpholine and the like. Examples of the peroxide include benzoyl peroxide, dicumyl peroxide and the like.

Examples of the vulcanization accelerator include thiuram vulcanization accelerators such as tetramethylthiuram disulfide and tetramethylthiuram monosulfide; zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate and dimethyldithiocarbamate. Dithiocarbamic acids such as sodium and tellurium diethyldithiocarbamate;
Organic accelerators such as thiazoles such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfenamide; thioureas such as trimethylthiourea and N, N'-diethylthiourea; or slaked lime, magnesium oxide; Titanium oxide, litharge (Pb
O) and the like.

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

Examples of antiaging agents include imidazoles such as 2-mercaptobenzimidazole; phenyl-α-naphthylamine, N, N'-di-β-naphthyl-
amines such as p-phenylenediamine and N-phenyl-N'-isopropyl-p-phenylenediamine; di-t
-Butyl-p-cresol, and phenolized nophenols.

As the reinforcing agent, carbon black is mainly used, and inorganic reinforcing agents such as silica-based or silicate-based white carbon, zinc white, surface-treated precipitated calcium carbonate, magnesium carbonate, talc, clay, etc. Alternatively, organic reinforcing agents such as coumarone indene resin, phenol resin, and 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; and organic fillers such as recycled rubber, powdered rubber, asphalts, styrene resin, and glue. Agents and the like. Examples of the softener include fatty acids (stearic acid, lauric acid, etc.),
Various softening agents of vegetable oil type, mineral oil type and synthetic type such as cottonseed oil, tall oil, asphalt substance, paraffin wax and the like can be mentioned.

Examples of the plasticizer include various plasticizers such as dibutyl phthalate, dioctyl phthalate, and tricresyl phosphate. In addition to the above, for example, a tackifier, a dispersant, a solvent, and the like may be appropriately blended with the rubber. As described above, the under blanket provided with the support layer and the surface rubber layer is used, for example, when the printing blanket is wound around the blanket cylinder of an offset printing press, interposed under the blanket. You.

[0021]

The present invention will be described below based on examples and comparative examples. Example 1 An NBR-based rubber paste for a surface rubber layer was coated on a 0.6 mm-thick polyester base cloth, dried, pressed, heated and vulcanized. Thereafter, the surface was polished to produce a flat under blanket (width 100 mm) having a total thickness of 1.0 mm.

Comparative Example 1 Two polyester base cloths having a thickness of 0.3 mm, NB
After laminating through an adhesive layer made of R-based rubber paste, the NBR-based rubber paste for the surface rubber layer, which is also an NBR-based paste, is dried, pressed, and heated. After vulcanization, the surface was polished to produce a flat under blanket (100 mm in width) having a total thickness of 1.0 mm.

The under blankets of the above Examples and Comparative Examples were subjected to the following constant displacement repetition test to evaluate the characteristics. Constant Displacement Repeating Test In a state in which a rubber printing blanket was superimposed on the under blanket of the example and the comparative example, it was wound around a blanket cylinder having a diameter of 30 mm and fixed.

A laminate of the under blanket and the printing blanket is compressed by pressing a cylinder having a diameter of 30 mm against the surface of the printing blanket at a speed of 0.246 mm / min while maintaining the cylinder parallel to the blanket cylinder. Then, the operation of distorting 0.1 mm in the thickness direction and then returning the cylinder to the original position at the same speed is repeated three times in order to stabilize the measured value. It was measured.

FIG. 1 shows the results of Example 1, and FIG. 2 shows the results of Comparative Example 1. As shown in these figures, the maximum value of the compression reaction force in the third compression in which the result is stable is 334.5 kgf in Comparative Example 1, whereas the maximum value in Comparative Example 1 is 104.5 kgf.
9 kgf, and Example 1 was about 3 times more than Comparative Example 1.
It was confirmed to be twice as flexible.

[0026]

As described in detail above, according to the present invention,
It has a unique effect of being able to provide an under blanket which is excellent in flexibility and has a simpler structure and is easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of a constant displacement repetition test of the under blanket of Example 1 of the present invention.

FIG. 2 is a graph showing the results of a constant displacement repetition test of the under blanket of Comparative Example 1.

Claims (1)

[Claims] A total thickness of 0.8 mm, comprising a support layer and a surface rubber layer, used for underlaying a printing blanket.
The under blanket described above, wherein the support layer is formed of one base cloth having a thickness of 50% or more of the total thickness.