JP2003001964A - Printing blanket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing blanket which prevents the generation of static electricity caused by friction with a printing plate to prevent damage of the printing plate made of plastics, preventing the generation and adhesion/ accumulation of a paper powder even when regenerated paper or the like is used, suppressing the generation of a waster liquid by reducing the washing number of times and capable of forming an image of high quality by high speed printing. SOLUTION: The printing blanket 10 is used, for example, in the transfer of ink to a paper medium and composed of a surface printing layer 11 using an oil-resistant rubber containing a conductivity imparting agent, a mixed rubber of the oil-resistant rubber and a low resistance rubber or the low resistance rubber and a support layer 12 including one or more base cloth layers. The surface resistivity of the surface printing layer 11 is not more than 1×10<9> Ω/square.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing blanket, and more particularly, at the time of transferring ink to a paper medium, high-speed and high-quality printing can be realized even on a low-quality paper medium such as recycled paper. Blanket for printing.

[0002]

2. Description of the Related Art Conventionally, in order to realize precision printing by offset printing, an approach has been taken from the viewpoint of enhancing the ink releasability of a printing blanket. From this viewpoint, a printing blanket (hereinafter referred to as "silicone blanket") provided with a surface printing layer made of silicone rubber having low surface energy has been proposed in recent years (Japanese Patent Laid-Open No. 7-
No. 171942, Japanese Patent Application Laid-Open No. 10-236013), this silicone blanket is suitable for the production of a printed matter with an extremely high added value. For example, in the ultra-precision printing in which the line width of the formed image is on the order of several μm. Has excellent functions.

However, in printing on a general paper medium, the above-mentioned ultra-precision printing is not required.
In addition, the material cost of the silicone blanket is high, and since the manufacturing process is complicated, the manufacturing cost is also extremely high. Therefore, it is not profitable to use the above-mentioned silicone blanket for printing on a general paper medium. On the other hand, in recent years, when printing on paper media,
The use of recycled paper is increasing from the viewpoint of resource saving, and paper powder is likely to be generated during printing due to the use of recycled paper of low quality.

Paper dust adheres to the surface of the printing blanket,
In such a case, an operation of wiping off the paper dust deposited and accumulated with a non-woven fabric containing a cleaning liquid, which is called a blanket washer, has been conventionally performed because the print quality is deteriorated when accumulated. However, the increase in the amount of paper dust caused by the use of recycled paper causes an increase in the frequency of cleaning the printing blanket, which causes a problem that the productivity of printing is reduced and the surface of the printing blanket is deteriorated.

Further, in recent years, from the viewpoint of environmental problems, it has been required to reduce waste liquids such as inks and cleaning liquids generated at the time of printing. In the waterless planographic printing, however, the generation of printing waste liquids is small and the printing productivity is good. Therefore, the adoption of this waterless planographic printing for printing on a paper medium is becoming widespread. However, a printing plate widely used for waterless lithographic printing is one in which a silicone rubber layer is provided on a substrate made of plastic such as polyester,
Static electricity is easily generated by repeated contact with the printing blanket. Therefore, there is a problem that the printing plate is easily damaged especially by repeating high-speed printing with an offset printing machine.

[0006] Although various studies have hitherto been made on printing blankets, the current situation is that sufficient studies have not been made on the prevention of static electricity associated with contact with a printing plate. Therefore, an object of the present invention is to prevent generation of static electricity due to friction with a printing plate to prevent damage to a plastic printing plate, and to generate paper dust even when a low-quality paper medium such as recycled paper is used. It is an object of the present invention to provide a printing blanket that prevents the occurrence of waste liquid by reducing the number of times of cleaning by preventing the occurrence of adhesion and deposition, and by reducing the number of cleaning times.

[0007]

MEANS TO SOLVE THE PROBLEMS AND EFFECTS OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that the rubber composition in the rubber composition forming the surface printing layer has conductivity. By using the given rubber or low resistance rubber, when the surface resistivity is set in a predetermined range,
Even if the plate is repeatedly contacted and separated at high speed with an offset printing machine, static electricity can be prevented and printing is performed on low-quality paper media such as recycled paper. However, the present invention has been completed by discovering a new fact that generation and adhesion of paper dust can be sufficiently suppressed, and therefore high-quality images can be formed by high-speed printing.

That is, the printing blanket according to the present invention comprises a surface printing layer comprising an oil resistant rubber containing a conductivity-imparting agent, a mixed rubber of the oil resistant rubber and a low resistance rubber or a low resistance rubber. Alternatively, it is characterized by comprising a support layer including two or more base cloth layers, and having a surface resistivity on the surface printing layer side of 1 × 10 ⁹ Ω / □ or less.

According to the printing blanket of the present invention, the surface printing layer, which is the outermost surface of the printing blanket and which is repeatedly contacted with and separated from the printing plate, is provided with a conductive rubber composition or a rubber composition. Since it is formed by using the composition of the resistance rubber, the surface of the printing blanket with low electric resistance (surface printing layer) even if static electricity is generated due to contact with the printing plate and separation during printing. Through, it is possible to disperse and remove the generated static electricity, and static electricity does not stay. Therefore, even when a plastic printing plate such as polyester is used, damage to the printing plate due to static electricity can be prevented.

Further, since the generation and accumulation of static electricity can be prevented, even when recycled paper of low quality is used as the paper medium, paper dust caused by contact and separation of the printing blanket and the paper medium. It is possible to suppress the occurrence of paper dust and the adhesion and accumulation of the paper powder on the printing blanket. Therefore, the printing blanket of the present invention is suitable as a printing blanket used for transferring ink to a paper medium. By the way, conventionally, a protrusion made of rubber particles is provided in the surface printing layer (JP-A-11-286186), or the surface shape (roughness) of the surface printing layer is controlled (JP-A-5-177968). Therefore, a printing blanket having improved paper discharge properties has been proposed. However, in the former case, the number of steps is increased, and in the latter case, strict condition control and material control in the polishing step are required, and both of them have a problem that the manufacturing cost of the printing blanket increases. Commonly, there is also a problem that print quality deteriorates.

In the printing blanket disclosed in JP-A-5-262068, the surface printing layer is formed by using a synthetic resin containing a fluorinated alkyl group in order to improve the paper discharge property. The material cost will be significantly increased by adding. Moreover, the fluorine compound has a low compatibility with the acrylonitrile-butadiene rubber (NBR) that is the base of the surface printing layer, making it difficult to knead, and its low solubility in toluene makes it difficult to knead the surface. There is a problem that the print layer cannot be formed.

Further, as a printing blanket for preventing the accumulation of paper dust (improving the residual paper dust) and improving the paper discharge property without deteriorating the printing quality, the volume change rate due to the swelling of the surface printing layer Alternatively, a printing blanket in which a surface printing layer is formed using a rubber composition having a hardness and a viscoelastic property tan δ of the surface printing layer satisfying a certain relationship (Japanese Patent Application Laid-Open Nos. 8-52954 and 8-52955). Gazette)
Alternatively, a printing blanket in which a surface printing layer is formed using a mixed rubber of an oil resistant rubber and a polysulfide rubber (Japanese Patent Laid-Open No. 5-85)
No. 080) has been proposed. However, when the printing blanket disclosed in the above publication is subjected to high-speed rotary printing using recycled paper, the effects of preventing the accumulation of paper dust and improving the paper discharge property become insufficient. There is a problem.

On the other hand, the printing blanket of the present invention can be manufactured by the usual process control and does not require special control of the surface shape.
It does not sacrifice print quality. Further, according to the printing blanket of the present invention, it is not necessary to use special and expensive rubber such as silicone rubber for the surface printing layer, and the material cost and manufacturing cost of the printing blanket can be suppressed.

In the printing blanket of the present invention,
It is preferred that the support layer comprises a compressible layer. When the support layer is of a so-called air type that includes a compressible layer, the compressive stress at the nip deformation part caused by pressure contact with the printing plate is lower than that of a solid type that does not have a compressible layer. It is possible to reduce the fluctuation of the compressive stress due to the change of the strain amount. Therefore, the printing blanket can be made to have excellent shock absorption, and printing defects such as bulging due to stress concentration on the nip deformation part, misregistration, paper feeding failure, double-sided, halftone dot pattern deformation, etc. Can be prevented.

In the printing blanket of the present invention, the oil resistant rubber is at least one selected from the group consisting of acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), urethane rubber and polysulfide rubber.
It is preferably a seed. The low resistance rubber is at least one selected from the group consisting of epichlorohydrin rubber (CO) and copolymer rubber of epichlorohydrin and ethylene oxide (epichlorohydrin-ethylene oxide rubber, ECO). Is preferred.

Generation of static electricity in the surface printing layer by using the rubber exemplified above as the oil resistant rubber and the low resistance rubber, that is, by using the above exemplified one as the main component of the rubber component constituting the surface printing layer. In addition to preventing the above, the structure of the surface printing layer can be made in consideration of printing quality. In the printing blanket of the present invention, the conductivity-imparting agent mixed with the oil-resistant rubber is a conductive filler, a metal powder or metal fiber, a conductive metal oxide,
It is preferably a conductive coating type conductive filler, carbon fiber and / or a conductive plasticizer. By using one of the above-mentioned examples as the conductivity-imparting agent, the surface resistivity can be set within an appropriate range without affecting the print quality or the moldability of the surface print layer.

In the printing blanket of the present invention, the surface printing layer preferably has a rubber hardness (IRHD) of 20 to 80. When the hardness of the surface printing layer satisfies the above range, the tackiness of the surface printing layer can be set in an appropriate range, and as a result, the printing quality can be made good.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a printing blanket according to the present invention will be described in detail. The printing blanket 10 of the present invention has a support layer 12 as shown in FIG.
The surface printing layer 11 is provided on the top. In the embodiment shown in FIG. 1, the support layer 12 is a base cloth layer (upper base cloth layer) 13 made of one cotton cloth in order from the surface printing layer 11 side.
d, the compressive layer 14, and the base cloth layers (lower base cloth layers) 13a, 13b, and 13c made of a laminated body of three cotton cloths are laminated.

The printing blanket of the present invention is not limited to the so-called air type as shown in FIG. 1, but may be a so-called solid type having no compressible layer. Further, the number of laminated cotton cloths in the support layer can be appropriately set according to the thickness, strength, etc. of the entire printing blanket. [Surface Printing Layer] The surface printing layer 11 in the printing blanket 10 of the present invention is provided on the surface of the printing blanket for receiving an ink image from the printing plate and transferring the ink image to the printing material. .

The surface printing layer 11 is prepared by, for example, preparing a rubber composition for forming the surface printing layer in the state of a rubber paste, and applying this to the surface of the support layer 12 to adjust it to a predetermined thickness. Obtained by Alternatively, it can be obtained by forming a rubber composition for forming a surface printing layer into a sheet shape in advance and then laminating it on the surface of the support layer 12. The rubber composition for forming the surface printing layer is generally a so-called oil-resistant rubber that is less swelled by ink, such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), urethane rubber, and polysulfide rubber.
Conventionally known vulcanizing agents, vulcanization accelerators, fillers, antioxidants,
A plasticizer, a reinforcing agent, a thickener and the like are appropriately blended according to a conventional method. The rubber paste for the surface printing layer is obtained by dissolving and swelling the above rubber composition in a suitable organic solvent such as toluene or methyl ethyl ketone (or a mixed solvent thereof).

In order to impart conductivity to the surface-printed layer so that its surface resistivity is 1 × 10 ⁹ Ω / □ or less, (i) a conductivity-imparting agent in the rubber composition for forming the surface-printed layer. And a method of using (ii) a low resistance rubber alone or in a mixture with an oil resistant rubber as the rubber component of the rubber composition forming the surface printing layer. (Conductivity imparting agent) Examples of the conductivity imparting agent used in the method (i) include conductive fillers, metal powders or metal fibers, conductive metal oxides, conductive coating type conductive fillers, carbon fibers, Examples include conductive plasticizers.

Of these, the conductive filler is not limited to these, and for example, acetylene black,
Conductive carbon black such as Ketjen black and graphite carbon can be used. Examples of the metal powder or metal fiber include those obtained by molding silver, nickel, copper, iron, stainless steel, aluminum, etc. into a powder form, a flake form or a whisker (short fiber) form.

As the conductive metal oxide, for example, conductive zinc oxide, conductive tin oxide, conductive titanium oxide, conductive indium oxide, or the like to which conductivity is imparted by giving a lattice defect to the metal oxide. Is mentioned. Examples of the conductive coating type conductive filler include whiskers (short fibers) or spherical potassium titanate, aluminum borate,
Particles of barium sulfate or the like whose surface is coated with metal oxide such as tin oxide or conductive carbon black, silver or the like; glass fiber, polyester fiber or glass beads coated with nickel or aluminum by electroless plating or the like; Etc.

As the conductive plasticizer, for example, a large amount of an alkali metal salt (such as a lithium compound) or a fourth compound in an ester compound such as dibutoxyethoxyethyl adipate is used.
Those containing a primary ammonium salt; those described in formulas (I) to (IV) and the like can be mentioned.

[0025]

[Chemical 1]

(In the formulas (1) to (5), R ¹ is an aliphatic or alicyclic dibasic acid residue having 2 to 8 carbon atoms, or a group: -C
1 shows a benzene ring which may have OO (R ² O) _m R ³ . R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is a linear or branched alkyl group, R ⁴ is an alkyl group or an alkenyl group, R ⁵ is a hydrogen atom or a methyl group,
R ⁶ is an aliphatic, alicyclic or aromatic carboxylic acid residue or an epoxycyclohexane ring carboxylic acid residue,
Shown respectively. m and n are the same or different and are 1 to 7
(The total carbon number of R ² and R ³ is 5
17). a is an integer of 3 to 20, b is an integer of 1 to 7, c is an integer of 1 to 7, d to h is an integer of 1 to 3,
x and y show the integer of 0-3, p shows the integer of 4-8, respectively. The conductive plasticizers represented by formulas (I) to (IV) are described in JP-A-60-181142 and JP-A-62-2653.
38, JP-A-64-9258, JP-A-2-
It is disclosed in JP-A-245038, JP-A-2-255852 and JP-A-2-261849.

The compounding amount of the conductivity-imparting agent is the degree of surface resistivity required for the surface printing layer, the type of rubber component used in the rubber composition for the surface printing layer, the type of conductivity-imparting agent used, and the conductivity. It is appropriately set according to the degree of conductivity of the property-imparting agent itself and is not particularly limited, but generally 100 parts by weight of the rubber component in the rubber composition used for forming the surface printing layer. To 1 to 120 parts by weight. When the compounding amount of the conductivity-imparting agent is less than the above range, sufficient conductivity may not be imparted to the oil resistant rubber. On the contrary, when the content of the conductivity-imparting agent exceeds the above range, the conductivity of the surface printing layer is increased (the electric resistance is lowered) to improve the residual paper dust and the discharge property, but The hardness may increase, and the solid inking property may decrease. The antistatic agent generally has a large effect of reducing the electric resistance of the rubber, and therefore the compounding amount thereof can be suppressed to be small. In addition, there is little fear that the printing performance of the surface printing layer will be adversely affected by blending the antistatic agent.

If there is a concern that the hardness of the rubber will increase due to the addition of the conductivity-imparting agent, the rubber composition can be softened by incorporating a liquid polymer into the rubber component. The liquid polymer is not particularly limited, but when NBR is used as the rubber component, it is preferable to use liquid NBR from the viewpoint of compatibility. However, if the hardness of the surface-printed layer is too low, the tackiness of the surface may be increased, and the paper-releasing property and the paper dust-retaining property may be reduced. The hardness of the surface-printed layer is preferably 20 to 80 in terms of international rubber hardness (IRHD) from the viewpoint of the balance between solid ink receptivity and paper releasability / paper dust retention.
It is more preferably 30 to 70.

(Low Resistance Rubber) Examples of the low resistance rubber used in the method (ii) include epichlorohydrin rubber (CO). Conventionally, the above-mentioned oil resistant rubber has been widely used for the surface printing layer of a printing blanket. Oil-resistant rubber has a volume resistivity of 1 × 10 ¹⁰ Ω ・
It was as high as cm or more, and had no conductivity by itself. On the other hand, epichlorohydrin rubber (CO)
And the like have a low volume resistivity of about 1 × 10 ⁷ to 1 × 10 ⁸ Ω · cm, the conductivity can be imparted to the surface printing layer only by using this low resistance rubber for the surface printing layer.

The above low resistance rubber can be used as a mixture with an oil resistant rubber such as NBR. The conductivity of the blended rubber can be adjusted by appropriately blending various conductivity-imparting agents. Furthermore, by adding polysulfide rubber, it is possible to improve the paper discharge property (paper release property) of the surface printing tank. (Physical Properties of Surface Printing Layer) In the printing blanket of the present invention, the surface resistivity of the surface printing layer is such that static electricity is not generated and stayed by contact with the printing plate and separation,
It is set to be 1 × 10 ⁹ Ω / □ (1000 MΩ / □) or less. When the surface resistivity of the surface printing layer exceeds the above range, it is impossible to prevent static electricity from being generated and staying on the surface printing layer due to contact and separation with the printing plate, which may cause damage to the printing plate. The surface resistivity of the surface printing layer is 1 × 10 ⁸ Ω / □ (100 MΩ /
□) or less, preferably 1 × 10 ⁷ Ω / □ (10
It is more preferable that it is MΩ / □ or less.

The thickness of the surface printing layer is not particularly limited, but is usually 0.05 to 1.0 mm, preferably 0.1 to 0.6 mm, more preferably 0.2 to 0.4 m.
It is set in the range of m. If the thickness is less than the above range, for example, a mesh pattern of the base cloth may appear in the printed image. On the other hand, if the thickness exceeds the above range, the distortion during printing may be too large and the print quality may be deteriorated. [Support Layer] The support layer 12 in the printing blanket 10 of the present invention is formed by laminating a plurality of base fabrics with a compressive layer interposed therebetween as necessary. The total thickness of the support layer is set according to the thickness and the number of the base cloth described later, the thickness of the compressible layer, the thickness of the entire printing blanket, etc., and is not particularly limited. Usually, it is set to be about 0.6 to 1.3 mm.

(Compressible Layer) The compressive layer 14 in the printing blanket 10 of the present invention may be the support layer 1 if necessary.
2 is a layer arranged inside 2, and is a sponge-like rubber layer having minute voids inside. The compressive layer 12 is prepared by, for example, preparing a rubber composition for forming the compressible layer in a state of rubber paste, and applying this to the surface of the base fabric layer (for example, the upper base fabric layer 13d) to give a predetermined thickness. It is obtained by adjusting and vulcanizing. When the internal pores are formed by the elution method described below, the elution operation may be performed after vulcanization.

The rubber composition for forming the compressible layer generally has the following composition.
Acrylonitrile-butadiene rubber (NBR), urethane rubber, chloroprene rubber (CR), polysulfide rubber, and other oil resistant rubbers are added to conventionally known vulcanizing agents, vulcanization accelerators, fillers,
An antiaging agent, a plasticizer, a reinforcing agent, a thickener, etc. are appropriately blended according to a conventional method, and further bubble-forming particles such as microcells (hollow fine particles), a foaming agent, and water-soluble fine particles are blended. Further, the rubber paste for the compressible layer is the above rubber composition,
It is dissolved and swollen in an appropriate organic solvent such as toluene or methyl ethyl ketone (or a mixed solvent thereof).

The compressive layer usually has a hardness according to JIS C.
The hardness is preferably in the range of 40 to 80, and the porosity thereof is preferably 30 to 60% from the viewpoint of exhibiting good compression performance. If the hardness of the compressible layer is less than the above range or if the porosity exceeds the above range, the strength of the compressible layer is reduced, so that the restorability is reduced and settling occurs, and the printing pressure required for printing is reduced. There is a risk that it will not be obtained. On the other hand, if the hardness exceeds the above range or the porosity falls below the above range, the compressibility decreases, and the impact absorbing effect of the compressible layer during printing becomes insufficient, causing printing failure. There is a risk. The hardness of the compressible layer is preferably 45 to 75, more preferably 50 to 70, in the above range. The porosity of the compressive layer is preferably 35 to 60%, and more preferably 40 to 55%, in the above range.

The voids of the compressible layer are closed cell forms obtained by compounding microcells and a foaming agent in a rubber paste for forming the compressible layer and foaming the mixture during vulcanization (microballoon method, foaming method). Continuous foam obtained by blending the water-soluble powder with the rubber paste for forming the compressible layer and extracting the water-soluble powder with warm water after vulcanization (leaching method). It may be in the form. Further, in the present invention, the bubbles of both forms may be used together.

The hardness and porosity of the compressible layer can be appropriately adjusted by the particle size of the bubble-forming particles, the amount added, and the like. In addition to the above, the hardness of the compressible layer can be adjusted by the vulcanization degree and the addition amount of a reinforcing agent, a filler, a plasticizer and the like. Examples of the water-soluble fine particles include particles of various organic substances and inorganic substances such as salt, starch, sugar, polyvinyl alcohol, gelatin, urea, cellulose, sodium sulfate and potassium chloride. The particle size of the water-soluble fine particles is generally preferably set in the range of 10 to 50 μm according to the size of the diameter required for the bubbles.

The microcell may be, for example, Nobel
Examples include Microballoon "Expansel" series manufactured by Industry, Microcapsules manufactured by Matsumoto Yushi-Seiyaku Co., Ltd., and the like. Further, a thermosetting resin such as a phenol resin or a shell formed of an inorganic material such as glass in which a gas such as air is enclosed may be used. Examples of the foaming agent include azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, p, p'-oxybisbenzenesulfonylhydrazide, and the like.

The thickness of the compressive layer is appropriately set according to the hardness and the porosity of the compressible layer, and further according to the value required for the compressive stress of the entire printing blanket. For blanket blanket thickness 10-50
It is set to be%. When the thickness of the compressible layer is less than the above range, the effect of absorbing impact during printing becomes insufficient. On the other hand, when the amount exceeds the above range, the compressive stress of the entire printing blanket decreases, and the printing pressure required for printing may not be obtained. Although not particularly limited, the thickness of the compressive layer is appropriately set in the range of 0.1 to 0.8 mm, preferably 0.2 to 0.5 mm.

(Base cloth layer) Printing blanket 1 of the present invention
The base fabric layers 13a to 13d in No. 0 are base fabrics such as cotton fabric impregnated with rubber paste. The upper limit of the number of laminated base fabric layers is not particularly limited, and may be appropriately set according to the thickness of the entire printing blanket and the like, but is usually 3 to 5.
A layer is suitable. As a base fabric that can be used for the base fabric layer, a plain weave fabric made of cotton, polyester, rayon, and a mixed fiber thereof, or a non-woven fabric made of the above material is preferable from the viewpoint of minimizing unevenness of the printing blanket. Is.

The thickness of the base cloth layer is set in the same manner as in the conventional blanket. Specifically, the thickness of one base cloth impregnated with the rubber paste is preferably about 0.2 to 0.5 mm. As the rubber paste with which the base cloth is impregnated, an oil resistant rubber is generally used. For example, a rubber material such as NBR, urethane rubber, CR, polysulfide rubber or the like is mixed with a predetermined amount of vulcanizing agent and vulcanization accelerating agent. A mixture of an agent and, if necessary, a thickener is used. In the present invention, instead of the woven fabric or the woven fabric exemplified above, for example, a film made of synthetic resin such as polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), nylon, aluminum, stainless steel, etc. It is also possible to use a thin metal plate of the above as a base fabric layer.

(Primer Layer) A primer layer (not shown) in the printing blanket 10 of the present invention plays a role of adhering the surface printing layer 11 and the support layer 12 and adhering the base cloth layers to each other. For example, rubber materials such as NBR, urethane rubber, CR, and polysulfide rubber are mixed with a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc., and if necessary, to give tackiness, A mixture of a thickener and a resin is used.

[0042]

[Manufacture of printing blankets]

Examples 1 to 5 Printing blankets were produced through the steps shown in (a) and (b) below. (a) Preparation of support layer Three pieces of cotton base cloth having a thickness of 0.3 mm are applied to a thickness of 0.01 mm.
Was laminated via the primer layer of. The primer layer was obtained by applying a rubber paste composed of a mixture of the formulation components for the primer layer shown in Table 1 and toluene (weight ratio of formulation components and toluene = 1: 2) to the surface of cotton cloth (thickness: 0). .01m
m).

[0043]

[Table 1]

In Table 1, "NBR" is acrylonitrile-
Butadiene rubber [trade name "Nip manufactured by Nippon Zeon Co., Ltd.
1001 "]," DOA "indicates dioctyl adipate," MBTS "indicates dibenzothiazyl disulfide (DM), and" TMTD "indicates tetramethylthiuram disulfide (TT). . On the other hand, one side of a cotton base cloth having a thickness of 0.3 mm is glued with a rubber paste for a compressible layer, and a vulcanization can (air pressure 2
A compressible layer having a thickness of 0.4 mm was formed on the surface of the base fabric by vulcanizing at 140 ° C. for 30 minutes at 140 kg / cm ² .

As the rubber paste for the compressible layer, a mixture of the compounding ingredients shown in Table 2 and toluene (weight ratio 1: 2) was used.

[0046]

[Table 2]

In Table 2, "DOA", "MBTS" and "TMTD" are the same as those in Table 1. "NBR" indicates acrylonitrile-butadiene rubber [trade name "Nipol DN206" manufactured by Nippon Zeon Co., Ltd.], and carbon black "HAF" indicates high abrasion resistance furnace black.
Then, the rubber paste for the primer layer is glued onto one surface (base cloth layer 13c side) of one of the laminates (base cloth layers 13a to 13c, lower base cloth layer) of the above base cloth to have a thickness of 0.01 mm. Was formed on the surface of the compressible layer 14. Thus, as shown in FIG. 1, the support layer 12 including the four base fabric layers (13a to 13d) and the compressive layer 14 was obtained. The primer layer is not shown in FIG.

(B) Formation of surface printing layer Of the support layer 12 obtained in (a) above, the base cloth layer 13d
A rubber paste for a surface printing layer is glued on the surface of the (upper base fabric layer) and vulcanized at 150 ° C. for 30 minutes by a continuous vulcanizer (pressure 2 kg / cm ² ) to give a support layer 12 on the support layer 12. The surface printing layer 11 having a thickness of 0.3 mm was formed (see FIG. 1).
As the rubber paste for the surface printing layer, a mixture of blending components shown in Table 3 below and toluene (weight ratio 1: 2) was used. That is, an acrylonitrile-butadiene rubber (NBR) as an oil resistant rubber was blended with a vulcanizing compounding agent and carbon black as a conductive filler to adjust its electric resistance. In addition, in Examples 1 to 5,
The hardness of the surface printing layer was changed by changing the compounding amount of the plasticizer DOA.

In Examples 1 to 5, the NBR was manufactured by Nippon Zeon Co., Ltd. under the trade name "Nipol DN223".
(Containing liquid NBR, volume resistivity 1 × 10 ¹¹ Ω · cm) was used, and the conductive carbon black used was a product name “Ketjen Black EC” manufactured by Ketjen Black International Co., Ltd. After forming the surface printing layer 11, the surface was buffed to obtain a printing blanket 10 having a total thickness of 1.98 mm.

Examples 6 to 10 and Comparative Example 1 NBR [trade name “Nipol manufactured by Nippon Zeon Co., Ltd.] is used as the oil resistant rubber used in the“ formation of surface printing layer ”of the above (b).
1042 ”, volume resistivity 1 × 10 ¹¹ Ω · cm], and acetylene black [trade name“ Denka Black ”manufactured by Denki Kagaku Kogyo Co., Ltd.] as a conductive carbon black.
Was used and the blending amount was set to the values shown in Table 4 to obtain a printing blanket in the same manner as in Example 5.
The product name "Nipol 1042" is liquid N
BR is not included.

Examples 11 to 15 Aluminum borate whisker-based white conductive filler with tin oxide coating as a conductive filler used in the "formation of surface printing layer" in (b) above [oxidization on the surface of aluminum borate fiber Filler formed by forming a thin film of tin; 9Al ₂ O ₃ ·
2B ₂ O ₃ / SnO ₂ ] was used, and the blending amount was set to the values shown in Table 5 to obtain a printing blanket in the same manner as in Examples 6 to 10. The aluminum borate whisker-based white conductive filler includes Mitsui Mining & Smelting Co., Ltd.
The product name “Pastran V” manufactured by the company was used.

Examples 16 and 17 and Comparative Example 2 As the oil-resistant rubber used in the "formation of the surface print layer" in the above (b), NBR was not used alone, but NBR ("Ni.
A printing blanket was obtained in the same manner as in Example 7, Example 12 or Comparative Example 1, except that the polysulfide rubber was used in combination. As the polysulfide rubber, a trade name "Thiocol LP2" manufactured by Thiocol was used.

Examples 18 to 22 NBR as an oil resistant rubber (the above-mentioned "Nipol") was used as the rubber component used in the "formation of the surface print layer" of the above (b).
1042 ") and epichlorohydrin-ethylene oxide rubber (ECO) as a low resistance rubber were used together, and a printing blanket was obtained in the same manner as in Comparative Example 1 using only NBR. For the ECO, the product name "Epichromer (R)" manufactured by Daiso Co., Ltd. (volume resistivity 5 × 10 ⁷
Ω · cm) was used.

Examples 23 and 24 As the rubber component used in the "formation of the surface print layer" of the above (b), NBR as an oil resistant rubber (the above-mentioned "Nipol") was used.
1042 ") and ECO (trade name" Epichromer (R) ") as a low resistance rubber, and acetylene black (" Denka Black "as described above) or aluminum borate whisker-based white conductive as a conductive filler. A printing blanket was obtained in the same manner as in Example 20, except that the filler (the above-mentioned "Pastran V") was also used.

Example 25 NBR as an oil resistant rubber (“Nipol 1042” described above) was used as a rubber component used for forming the surface printing layer.
And polysulfide rubber (“Thiocol LP2” mentioned above) and ECO rubber as low resistance rubber (“Epicromer (R)”, trade name mentioned above) are used in combination, and boro as a conductive filler is added to this. A printing blanket was obtained in the same manner as in Comparative Example 2 in which NBR was used alone, except that the aluminum acid whisker-based white conductive filler (“pastran V” described above) was blended.

Examples 26 to 28 NBR ("Nipol 1042" described above) was used as a rubber component used for forming the surface printing layer, and this NBR was used.
In the same manner as in Comparative Example 1 in which NBR was used alone, except that a lithium ion-containing polyether compound [Sanko Chemical Co., Ltd. 0862-20R] manufactured by Sanko Kagaku Kogyo Co., Ltd. was used as a conductive plasticizer. A blanket for printing was obtained.

[Evaluation of Physical Properties] (1) Rubber Hardness A test piece (thickness: 0.3 mm) was prepared by slicing the surface printing layer of the printing blanket obtained in the above Examples and Comparative Examples.
Was prepared, and the international rubber hardness (IRH
D) was measured according to the method specified in ISO 48. (2) Surface resistivity The surface resistivity (Ω / □) of the printing blankets obtained in the above Examples and Comparative Examples was measured.

A ring electrode resistance measuring instrument [manufactured by Mitsubishi Chemical Co., Ltd.] was used for the measurement, and the applied voltage during the measurement was set to 10V. In Tables 3 to 10 below, the value of the surface resistivity is M
It was expressed in Ω / □ (1 × 10 ⁶ Ω / □). [Evaluation of Printing Properties] Each of the printing blankets obtained in the above-mentioned Examples and Comparative Examples was attached to a printing machine (560 type) manufactured by Ryobi Co., Ltd., and solid printing was performed.

Waterless planographic ink [trade name "Dry Ocolor Naturalis" manufactured by Dainippon Ink and Chemicals, Inc.] is used as the printing ink, and coated paper [a product manufactured by Nippon Paper Industries Co., Ltd.] is used as the printing paper. The name "Alps"] was used and the printing plate used was a waterless planographic printing plate made of polyester [trade name "Pearl Dry Plate" manufactured by Prestec). The printing speed was set to 10,000 sheets per hour. (A) The image formed on the solid ink-carrying coated paper was analyzed, and the density distribution of the solid part was measured based on the value of the brightness. The standard deviation was calculated for this concentration distribution, and the solid inking property was evaluated by the degree of the deviation value.

The values of the above standard deviations are shown in the columns of "solid receptivity" in Tables 3 to 10. The smaller the standard deviation value is, the smaller the variation in image density is, and the better the solid receptivity is. The value of the brightness standard deviation is required to be 22 or less in order to make the solid inking property appropriate. The value of the brightness standard deviation is particularly preferably 20 or less, and more preferably 15 or less in the above range. (B) 10 sheets of coated paper on which an image of the dischargeable solid is formed, and the height (mm) of curl generated at the edge of the coated paper is measured,
The paper discharge property was evaluated based on the height.

The curl height values (mm) are shown in Tables 3 to 10.
"Dischargeability" column of. The lower the curl height,
It shows that the paper ejection property is good. The curl height is required to be 35 mm or less in order to make the paper ejection property proper. The curl height value is particularly preferably 30 mm or less, and more preferably 25 mm or less, within the above range. (C) Paper dust residue printing After printing 10,000 times on the coated paper, measure the total number (paper pieces) of paper dust adhered to the surface (400 mm x 400 mm) of the printing blanket, and according to the degree of the number The residual property of paper dust was evaluated.

The values (numbers) of the above paper dusts are shown in the columns of "Paper dust remaining property" in Tables 3 to 10. The smaller the value of paper dust retention, the lower the generation rate of paper dust, indicating that the deterioration of print quality is prevented. In order to maintain the quality of printed images, it is required that the number of paper particles attached to the surface of the printing blanket be 15 or less. The value of the brightness standard deviation is preferably 10 or less, and more preferably 5 or less, in the above range.

The evaluation results of (A) to (C) above are shown in Tables 3 to 10 together with the compounding composition of the rubber composition for forming the surface printing layer in each of Examples and Comparative Examples.

[0064]

[Table 3]

[0065]

[Table 4]

[0066]

[Table 5]

[0067]

[Table 6]

[0068]

[Table 7]

[0069]

[Table 8]

[0070]

[Table 9]

[0071]

[Table 10]

In Tables 3 to 10, the compound names and substance names of the plasticizer "DOA" and the vulcanization accelerator "MBTS" are the same as those in Table 1. "Nipol" in the oil-resistant rubber "NBR" column is a trade name of Nippon Zeon Co., Ltd. Oil-resistant rubber "polysulfide rubber" (trade name "Thiocol LP2" above), low resistance rubber "ECO" epichlorohydrin-ethylene oxide rubber (trade name "Epichromer (R)" above) , The conductive filler "Ketjen Black" is the above trade name "Ketjen Black EC", the conductive filler "acetylene black" is the above trade name "Denka Black", the conductive filler "Hou" Aluminum acid whiskers "are aluminum borate whisker white conductive fillers (trade name" Pastran V "described above), and conductive plasticizers are lithium ion-containing polyether compounds (trade names" Sanconol 0862- "). 20R "), and the anti-aging agent" NiDB
"C" is nickel dibutyldithiocarbamate (NBC)
The filler "CaCO ₃ " represents calcium carbonate, and the vulcanization accelerator "TETD" represents tetraethylthiuram disulfide (TET).

Physical property evaluations in Examples and Comparative Examples of the present invention will be described in detail below based on the data disclosed in Tables 3 to 10 above. (Examples 1 to 15) The oil-resistant rubber used for forming the surface-printed layer is mixed with a conductive filler such as acetylene black or aluminum borate whisker-based white conductive filler to prepare the surface-printed layer having electrical conductivity. I was able to lower the resistance. In addition, the surface resistivity of the surface printing layer is 1 × 10 ⁹
In the examples adjusted to be Ω / □ or less, the paper dust remaining property and the paper discharge property could be improved.

However, when the amount of the conductive filler compounded increased, the hardness of the surface printing layer increased and the solid inking property tended to decrease. (Examples 16 and 17 and Comparative Example 2) By using NBR and polysulfide rubber together as the oil resistant rubber used for forming the surface printing layer, it was possible to further improve the paper discharge property. However, since the hardness of the surface printing layer increases,
The solid inking property tended to decrease.

(Examples 18 to 25) The rubber component used in the formation of the surface printing layer was used in combination with epichlorohydrin-ethylene oxide rubber (ECO) which was originally a rubber having a low electric resistance (low resistance rubber). As a result, it was possible to sufficiently reduce the resistance of the surface printing layer even if the blending amount of the conductive filler was reduced. Therefore, in this case, it is possible to suppress an increase in hardness due to the blending of the conductive filler.

Further, the surface resistivity of the surface printing layer is set to 1 × 10.
By adjusting the resistance to ⁹ Ω / □ or less, both the paper dust remaining property and the solid inking property could be made good. Further, by using the polysulfide rubber together, it was possible to improve the paper discharge property. (Examples 26 to 28) As is clear from Examples 1 to 25, when a conductive filler is added, the hardness of the surface printing layer tends to increase, but a conductive plasticizer is used as the conductivity imparting agent. In such a case, it is possible to achieve a sufficiently low resistance with a small amount of addition, and the problem of hardness increase does not occur. It was also found that there was no problem in printing performance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a printing blanket according to the present invention.

[Explanation of symbols]

10 Printing blanket 11 Surface printing layer 12 Support layer 14 Compressible layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 101/00 C08L 101/00 (72) Inventor Toshio Kamata 3-6 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo No. 9 Sumitomo Rubber Industries Ltd. (72) Inventor Seiji Banno 3-6-9 Wakihama-cho, Chuo-ku, Kobe, Hyogo Prefecture Sumitomo Rubber Industries Ltd. F-term (reference) 2H114 CA03 CA04 CA10 DA46 EA08 FA04 4J002 AC071 AC091 CH041 CK021 CN021 DA016 DA066 FA046 FB076 FB286 FD116 GM00

Claims (6)

[Claims] 1. A surface printing layer comprising an oil resistant rubber containing a conductivity-imparting agent, a mixed rubber of an oil resistant rubber and a low resistance rubber or a low resistance rubber, and one or more base cloth layers. A printing blanket comprising a support layer and having a surface resistivity of 1 × 10 ⁹ Ω / □ or less. 2. The printing blanket of claim 1, wherein the support layer comprises a compressible layer. 3. The printing blanket according to claim 1, wherein the oil resistant rubber is at least one selected from the group consisting of acrylonitrile-butadiene rubber, chloroprene rubber, urethane rubber and polysulfide rubber. 4. The printing blanket according to claim 1, wherein the low resistance rubber is epichlorohydrin rubber or a copolymer rubber of epichlorohydrin and ethylene oxide. 5. The conductive agent is a conductive filler, metal powder or metal fiber, conductive metal oxide, conductive coating type conductive filler, carbon fiber and / or conductive plasticizer. The printing blanket according to any one of 4 to 4. 6. The surface printing layer has a rubber hardness (IRHD).
The printing blanket according to claim 1, wherein the printing blanket is 20 to 80.