JP3187728B2 - 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 printing blanket used for offset printing.

[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 a support layer on which a base fabric is laminated. In recent years, in order to respond to faster printing machines and higher image quality of printed images,
A so-called air-type printing blanket, in which a porous compressible layer also made of an elastomer such as rubber is interposed between the support layer and the surface printing layer, is becoming popular.

[0003] The air-type printing blanket has a lower compressive stress at a nip deformation portion caused by press contact with a plate cylinder or the like, and is accompanied by a change in distortion, as compared with a solid-type printing blanket having no compressible layer. Good shock absorption due to small fluctuations in compressive stress.For example, the shock generated during feeding of the printing press gear or a flat blanket seam wound around the blanket cylinder passes through the nip deformation section. It has an excellent effect of preventing impacts or the like generated at the time from affecting printing accuracy.

A solid type printing blanket causes a so-called bulge due to stress concentration on the surface printing layer at the nip deformation portion, causing misregistration due to circumferential elongation, poor paper feed, double, dot pattern. Printing defects such as deformation (especially thickening of halftone dots) may occur. However, in air-type printing blankets, the compressive layer acts to reduce stress concentration on the surface printing layer. This also has the effect of preventing the occurrence of defective printing.

The above-mentioned compressible layer is formed, for example, by foaming a matrix rubber with a foaming agent which decomposes upon heating to generate a gas, or by blending hollow fine particles into the matrix rubber. Are dispersed in a matrix rubber, and particles having an independent pore structure, each of which has an independent pore structure, and a solvent that does not affect the rubber (eg, water in the case of salt) are vulcanized. Of a continuous pore structure in which each pore communicates with each other, which is formed by a so-called leaching method.

[0006]

However, since the above-described compressible layers have both advantages and disadvantages, a printing blanket having a compressible layer having a structure particularly required for printing has conventionally been used. However, the disadvantage of the compressible layer is that it has to be used with the eyes closed.

That is, since the compressible layer having the independent pore structure has a high tensile strength against the shearing force due to the pressure contact of the plate cylinder or the like, it has the property of quickly returning to the original shape after being deformed by compression as compared with the continuous pore structure. In other words, it has the advantage of excellent resilience. Therefore, such a printing blanket having a compressible layer having an independent pore structure, which has a compressible layer having a continuous pore structure, does not promptly recover after passing through the nip deformed portion until reaching the next nip deformed portion. Causes so-called settling, and the printing pressure shows a tendency to drop below a predetermined value.
Particularly in high-speed printing, there is an advantage that a predetermined printing pressure can be maintained.

Further, the printing blanket having the compressible layer having the independent pore structure can be quickly restored after being partially deformed, for example, by foreign matter being interposed between the printing cylinder and the plate blank. There is also an advantage that printing defects in which traces of deformation appear on printed matter can be minimized. However, the compressible layer with the closed pore structure has a higher compressive stress at the nip deformation part and a larger fluctuation of the compressive stress due to the change of the strain amount than the continuous porous structure, so that the shock absorbing The printing blanket having such a compressible layer having an independent pore structure has a problem that printing accuracy is likely to be affected by, for example, an impact generated when a gear of a printing press is fed.

On the other hand, the compressive layer having the continuous pore structure has a lower compressive stress at the nip deformation portion and a smaller change in the compressive stress due to a change in the strain amount than the one having the independent pore structure as described above. In addition, the printing blanket having the compressive layer having the continuous pore structure has an advantage that it has an excellent effect of preventing impact from affecting printing accuracy. There are advantages.

However, since the compressible layer having the continuous pore structure has a disadvantage of low restorability as described above, the printing blanket having the compressible layer having the continuous pore structure may cause the settling described above, There is a problem in that a large number of printing defects in which traces of deformation due to foreign matter appear on printed matter are likely to occur. Further, the compressible layer of the continuous pore structure,
There is a disadvantage that the tensile strength against the shearing force due to the pressure contact of the plate cylinder or the like is low, so that elongation in the circumferential direction is apt to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide both of the advantages of a compressible layer having an independent pore structure and a compressible layer having a continuous pore structure. It is to provide a printing blanket having characteristics.

[0012]

[MEANS FOR SOLVING THE PROBLEMS]
Of the printing blanket of the present invention
Below,  With independent poresDoes not affect rubber
Disperse particles extractable by solvent into matrix rubber,
Formed by extracting particles after vulcanizing rubber
WasProviding a porous compressible layer having continuous pores
It is characterized by the following. The present invention having the above configuration
The printing blanket has a porous compressible layer as described above.
Has both independent pores and continuous pores,
Conventional compressible layer with independent pore structure and pressure with continuous pore structure
It has both advantages of the elastic layer.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a printing blanket of the present invention will be described with reference to the drawings showing an example of the embodiment. First, the examples of FIGS. 1A and 1B and FIG. 2 will be described. The printing blanket 1 of the above example has a flat plate shape as shown in FIG. 2, and has a support layer 11, a compressible layer 12, a reinforcing layer 13, as shown in FIG. The surface print layer 14 is laminated in this order.

The compressible layer 12 is formed of a porous matrix rubber 12a having independent pores CC and continuous pores OC as shown in FIG. 1 (b). The independent pores CC and the continuous pores OC may be regularly distributed in the compressible layer 12, for example, in a concentric manner, but the effect of the coexistence of both pores CC and OC will be described below.
In order to homogenize over the entire surface, it is preferable that both pores CC and OC are randomly mixed as shown in FIG. 1 (b).

The compressible layer 12 is not limited to the above, but the hardness of the matrix rubber is determined according to JIS.
In the range of 40 to 80 ° represented by A hardness, the entire porosity of the compressible layer 12 is 30 to 60%, and the total porosity of the compressible layer 12 is occupied in all the pores CC and OC.
It is preferable that the ratio of the closed pores CC is 10 to 70% by volume.

If the hardness of the matrix rubber constituting the compressible layer 12 is less than the above range, the overall strength of the compressible layer 12 is reduced, so that the resilience is reduced or the printing pressure required for printing is reduced. May not be obtained. Conversely, if the hardness of the matrix rubber exceeds the above range, the compressibility is reduced, and the volume change of the compressible layer at the time of printing is prevented, so that a bulge occurs on the surface printing layer 14,
It may cause print trouble.

The hardness of the matrix rubber is preferably 45 to 75 ° in the above range, and more preferably 50 to 7 °.
More preferably, it is 0 °. When the porosity of the compressible layer 12 is less than the above range, the amounts of the independent pores CC and the continuous pores OC in the layer are both insufficient, and the effect of maintaining the resilience by the independent pores CC is insufficient. At the same time, the shock absorption by the continuous pores OC may be insufficient. Conversely, if the porosity of the compressible layer 12 exceeds the above range, the overall strength of the compressible layer 12 is reduced, so that the resilience is also reduced, or the printing pressure required for printing is also reduced. There is a possibility that a problem that it cannot be obtained may occur.

The porosity of the compressible layer 12 is preferably within a range from 35 to 60%, and more preferably within a range from 40 to 5%.
More preferably, it is 5%. Further, the compressible layer 12
Independent pore C occupying in all pores CC and OC contained in
If the proportion of C is less than the above range, the effect of maintaining the resilience by the independent pores CC may be insufficient. Conversely, when the proportion of the independent pores CC exceeds the above range, the proportion of the continuous pores OC is relatively reduced, so that the shock absorption by the continuous pores OC may be insufficient.

The proportion of the closed pores CC is preferably 20 to 60% by volume within the above range, and more preferably 40 to 60% by volume.
More preferably, it is 50% by volume. The compressible layer 1
2 is 10 times the total thickness of the printing blanket 1.
It is preferably about 50%. When the thickness of the compressible layer 12 is less than the above range, the function of the compressible layer 12, that is, the effect of maintaining the resilience by the independent pores CC described above becomes insufficient, and the shock absorption by the continuous pores OC becomes insufficient. It may be insufficient. Conversely, the compressible layer 12
If the thickness exceeds the above range, the overall compressive stress is reduced, which may cause a problem that the printing pressure required for printing cannot be obtained.

The thickness of the compressible layer 12 is preferably 15 to 45% in the above range, and more preferably 20 to 40%.
% Is more preferable. The compressible layer 12 is
It is formed by a method that combines a method of forming a compressible layer having an independent pore structure by blending a foaming agent and hollow fine particles with a method of forming a compressible layer having a continuous pore structure by a leaching method.
It is .

Specifically, when an unvulcanized matrix rubber is dissolved in a suitable solvent, a foaming agent or hollow fine particles that form the independent pores CC and a source of the continuous pores OC are formed.
A rubber paste mixed with the particles for the leaching method is prepared, and this rubber paste is used as a base cloth (in the example shown in the figure, the base cloth of the uppermost layer of the support layer 11 or the reinforcing layer 13). And then dried and then vulcanized by heating.

Then, when a foaming agent is used, the foaming agent is decomposed by the heat during the vulcanization to generate gas,
Thereby, independent pores CC are formed in the matrix rubber. In the case of hollow microparticles, it goes without saying that independent pores CC are formed simultaneously with the compounding. Thereafter, when the particles for the leaching method dispersed in the formed layer are extracted with a suitable solvent, the traces of the particles become continuous pores OC, and the independent pores CC and the continuous pores OC are mixed as described above. A porous compressible layer 12 is formed.

The compressible layer 12 uses an unvulcanized rubber sheet formed from a rubber compound obtained by adding a foaming agent, hollow fine particles, particles for a leaching method, etc. to unvulcanized rubber. It can be formed in the same manner as above.
The matrix rubber constituting the compressible layer 12 includes:
Various rubbers can be mentioned, and in particular, those having excellent oil resistance are preferable in consideration of the resistance to inks and cleaning liquids. Examples of such oil-resistant rubber include, but are not limited to, acrylonitrile-butadiene copolymer rubber ( NBR), chloroprene rubber (CR), urethane rubber (U) and the like.

In order to keep the hardness of the matrix rubber within the above range, the degree of vulcanization may be adjusted, or the amounts of reinforcing agents, fillers, plasticizers and the like to be incorporated in the rubber may be adjusted. Further, as the foaming agent blended to form the closed pores CC in the compressible layer 12, any of various foaming agents conventionally known for rubber can be used.

Specific examples of such a foaming agent include, but are not limited to, azodicarbonamide, N,
N'-dinitrosopentamethylenetetramine, p, p '
-Oxybisbenzenesulfonylhydrazide and the like. On the other hand, as hollow microparticles, those in which a gas such as air is sealed in a closed shell formed of a thermoplastic resin, a thermosetting resin such as a phenol resin, or an inorganic material such as glass. The shell formed of a flexible thermoplastic resin is particularly suitable for the compressible layer 12.
It is preferable from the viewpoint of maintaining flexibility.

Examples of the hollow fine particles having a shell made of a thermoplastic resin include, but are not limited to,
Expancel series manufactured by EXPANCEL Co., Ltd. having a shell formed of a copolymer of vinylidene chloride and acrylonitrile. Further, as particles for forming the continuous pores OC by the leaching method, it is advantageous in terms of safety and cost to use water as a solvent for extraction, so particles that can be extracted with water are preferably used. used.

Examples of such water-extractable particles include various water-soluble organic and inorganic particles such as salt, starch, sugar, polyvinyl alcohol, gelatin, urea, cellulose, sodium sulfate, and potassium chloride. Can be The addition amount of the foaming agent, or hollow fine particles, the particle size and the addition amount of the particles for the leaching method,
The porosity of the compressible layer 12 or the closed pore C
It is set as appropriate according to the ratio of C and the continuous pore OC.

The support layer 11, the reinforcing layer 13, and the surface printing layer 14 constituting the printing blanket 1 together with the compressible layer 12 can have the same structure as the conventional one. For example, the support layer 11 is formed by laminating a plurality of base cloths (three sheets in the figure) made of a woven or non-woven cloth of cotton, polyester, rayon, or the like via rubber glue for bonding.
It is formed by vulcanizing the rubber paste. The reinforcing layer 13 is also formed of the same base cloth as described above.

Further, the surface printing layer 14 is formed by applying rubber paste,
It is formed by vulcanizing an unvulcanized rubber layer formed by drying or an unvulcanized rubber sheet made of a rubber compound. As the rubber constituting the surface printing layer 14, for example, the above-described oil-resistant rubber such as NBR, CR, and U is preferably used, and polysulfide rubber (T), hydrogenated NBR, and the like can also be used. .

The thickness of each of the above-mentioned layers may be about the same as the conventional one.
Specifically, the thickness of the base fabric constituting the support layer 11 and the reinforcing layer 13 is about 0.2 to 0.5 mm, and the thickness of the support layer 11 on which the base fabric is laminated is 0.6 to 1.3 mm. It is preferable that the thickness of the surface print layer 14 is about 0.1 to 1.0 mm. Each of the above-mentioned layers constituting the printing blanket 1 is bonded simultaneously with the vulcanization of both layers in a state where the unvulcanized layers are laminated directly or via an adhesive rubber paste. In the state of laminating the uncured layer and the vulcanized layer directly or via a bonding rubber glue, the unvulcanized layer is adhered at the same time as the vulcanized layer. In the state of being laminated via the glue, the rubber glue is bonded by vulcanization, or the like.

In view of extracting particles for the leaching method, it is preferable that the compressible layer 12 is vulcanized before laminating another layer on at least one surface to extract the particles. The flat printing blanket 1 is mounted on a blanket cylinder shaft directly or via an underlay material. Next, an example of FIGS. 3A and 3B will be described.

The printing blanket 2 of the above example is shown in FIG.
Is formed on the outer peripheral surface of the cylindrical sleeve 20 as shown in FIG.
On top, a base layer 21, a support layer 22, and a compressible layer 23
And the surface print layer 24 are laminated in this order.
As shown in FIG. 1 (b), the compressible layer 23 is formed in a seamless cylindrical shape by a porous matrix rubber 23a having a mixture of independent pores CC and continuous pores OC, as in the previous example. Is done.

The porosity of the compressible layer 23 and the compressible layer 2
Independent pore CC in all pores CC and OC contained in 3
About the ratio of and continuous pore OC, the same range as the above is preferable. The reason is as described above. In the case of the example shown in the drawing, the thickness of the compressible layer 23 is such that the adhesive may be provided between the base layer 21, the support layer 22, the compressible layer 23, and the surface print layer 24, except for the sleeve 20, and between the above-mentioned layers. It is preferably about 10 to 50% of the total thickness of the layer.
The reason is also as described above.

The method of forming the compressible layer 23 is the same as described above. In order to form the compressible layer 23 into a seamless cylindrical shape, a rubber paste containing the foaming agent, hollow fine particles, particles for a leaching method, and the like is applied to the entire surface of the support layer 22, Vulcanization may be performed after drying. Further, a state in which an unvulcanized rubber sheet formed from a rubber compound containing a foaming agent, hollow fine particles, particles for a leaching method and the like is wound on the support layer 22 via an adhesive rubber paste. And the seam in the circumferential direction may be welded and integrated together with the vulcanization.

The matrix rubber, foaming agent, hollow fine particles, particles for the leaching method, and the like constituting the compressible layer 23 include the same materials as described above. The sleeve 20, the base layer 21, the support layer 22, and the surface printing layer 24, which constitute the printing blanket 2 together with the compressible layer 23, can have the same configuration as the conventional one.

For example, the sleeve 20 may be made of a very thin metal material such as a nickel thin plate, or may be made of glass fiber reinforced plastic. The base layer 21 and the surface printing layer 24 are formed by vulcanizing an unvulcanized rubber layer formed by applying and drying a rubber paste or an unvulcanized rubber sheet made of a rubber compound, respectively. Both layers are formed in a seamless cylindrical shape. The method is the same as in the case of the compressible layer 23.

As the rubber constituting the base layer 21 among the above, for example, the above-described oil-resistant rubber such as NBR, CR and U is suitably used. On the other hand, as the rubber constituting the surface print layer 24, NBR, CR, U,
T and hydrogenated NBR. Support layer 22
Is cotton thread, polyester thread, rayon thread, nylon thread,
It is formed by winding a non-stretchable wire such as an aromatic polyamide thread around the base layer 21 coated with rubber glue while applying tension, and then vulcanizing and fixing the rubber glue. You.

The thickness of each of the above layers may be the same as described above.
Further, the diameter of the wire constituting the support layer 22 may be the same as that of the related art. Specifically, the diameter of the wire is 0.1 to
It is preferably about 0.5 mm. Each of the above-mentioned layers constituting the printing blanket 2 is sequentially laminated from a layer close to the sleeve 20 to an outer layer. Each layer may be vulcanized each time it is formed, or a plurality of layers may be vulcanized collectively.
For example, the compressible layer 23 is vulcanized before laminating the surface printing layer 24 in order to extract particles for the leaching method,
Preferably, the particles have been extracted.

The cylindrical printing blanket 1 is used by extrapolating to a blanket cylinder shaft of a printing press. Various additives can be blended into the rubber compound and the rubber paste of each layer constituting the printing blankets 1 and 2 of the example described above in the same manner as in the related art. Such additives include:
For example, vulcanizing agents, vulcanization accelerators, vulcanization acceleration aids, other agents for vulcanizing rubber such as vulcanization retarders, anti-aging agents,
Examples include a reinforcing agent, a filler, a softener, and a plasticizer. The amounts of these additives may be the same as in the conventional case.

Among the above, the vulcanizing agents include, for example, sulfur, organic sulfur-containing compounds, organic peroxides, etc. Among them, the organic sulfur-containing compounds include, for example, N, N'-
Examples include dithiobismorpholine, and examples of the organic 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;
Dithiocarbamic acids such as zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, sodium dimethyldithiocarbamate and tellurium diethyldithiocarbamate; 2-mercaptobenzothiazole, N-cyclohexyl-2-benzothiazolesulfenamide and the like Thiazoles; organic accelerators such as thioureas such as trimethylthiourea and N, N'-diethylthiourea;
Alternatively, inorganic accelerators such as slaked lime, magnesium oxide, titanium oxide, and litharge (PbO) can be used.

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. In addition, the configuration of the printing blanket of the present invention is not limited to the example of the diagram described above,
Various design changes can be made without changing the gist of the present invention.

For example, the position of the compressible layer 12 in the flat printing blanket 1 shown in FIGS. 1A and 1B and FIG. 2 or the configuration of other layers can be appropriately changed. Similarly, the position of the compressible layer 23 in the cylindrical printing blanket 2 shown in FIGS. 3A and 3B and the configuration of other layers can be appropriately changed.

In short, if the compressible layer provided below the surface printing layer has independent pores and continuous pores,
Other configurations are not particularly limited in the present invention.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Examples 1 to 20, Comparative Examples 1 to 10 After three cotton cloths each having a thickness of 0.3 mm as a base cloth were laminated via an adhesive layer made of NBR-based rubber paste,
100 parts by weight of NBR [N236H manufactured by Nippon Synthetic Rubber Co., Ltd.] and hollow fine particles of the amounts shown in Tables 1 to 3 [the above-mentioned Expansel Co., Ltd. EXPANCEL 091DE100, particle size 10-100μ
m], and a rubber paste for a compressible layer composed of the following components and particles of sodium chloride (particle size 1 to 100 μm), dried, pressed, heated and vulcanized. Particles of
A leaching treatment for immersion and extraction in warm water at 80 ° C. for 5 hours was performed, followed by drying to form a laminate in which a 0.5 mm-thick compressible layer was laminated on a 0.95 mm-thick support layer. .

(Component) (parts by weight) • Reinforcing agent Carbon black GPF 50 • Vulcanizing agent Sulfur 2 • Vulcanizing accelerator Tetramethylthiuram disulfide (* 1) 1 N-cyclohexyl-2-benzothiazolyl sulfenamide (* 2) 2 ・ Vulcanization Accelerator Zinc Oxide 5 Stearic Acid 1 * 1: Noxeller TT manufactured by Ouchi Shinko Chemical Co., Ltd. * 2: Noxeller CZ manufactured by Ouchi Shinko Chemical Co., Ltd. On the compressible layer, as a base cloth,
After laminating one piece of cotton cloth having a thickness of 0.25 mm via an adhesive layer made of NBR-based rubber paste, the rubber paste for the surface printing layer, which is also NBR-based, is pasted on the base cloth. After drying and pressurizing, heating and vulcanizing, the surface is polished to form a surface printing layer having a thickness of 0.25 mm, and has a layer structure shown in FIG. Was produced.

The printing blankets manufactured in the above Examples and Comparative Examples were subjected to the following tests to evaluate the characteristics. Evaluation of the porosity of the compressible layer The porosity of the entire compressible layer of each of the printing blankets described above, and the proportion of independent pores in all the pores contained in the compressible layer, the ratio of the independent pores of the micrograph of the sample cross section, respectively From the actual measurement, it was determined as an area ratio. In addition, the above-mentioned actual measurement was performed at ten locations for one sample, and the area ratio was an average value of data at ten locations.

The results are shown in Tables 1 to 3.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

Observation of Compressible Layer Each of the printing blankets was cut in the thickness direction, and the internal structure of the compressible layer was observed with a microscope. Are closed pores CC and continuous pores O as shown in FIG. 1 (b).
It was confirmed that C and C were randomly mixed.

On the other hand, in each of the compressible layers of the printing blankets of Comparative Examples 1, 3, 5, 7, and 9 in which no hollow fine particles were blended, only continuous pores, which are traces of extraction of salt particles, were observed. Was. Further, in each of the compressible layers of the printing blankets of Comparative Examples 2, 4, 6, 8, and 10 in which no salt particles were blended, only independent pores due to the hollow fine particles were observed.

Restorability Test Each printing blanket was extrapolated to the blanket cylinder shaft of an offset printing machine (Model 560, manufactured by Ryobi Co., Ltd.), and the plate cylinder was pressed against the printing cylinder at a printing pressure of 15/100 mm. Next, a 0.2 mm-thick 10 mm thick paper was coated at the center of coated paper (Utrilo Coat, Daio Paper Co., Ltd.
A piece of cardboard with a cm-square is attached, and the cardboard is clamped between the plate cylinder and the printing blanket so that the cardboard faces the printing blanket, and the surface of the printing blanket is partially deformed. Was.

Next, a printing pressure of 15/100 mm and a printing speed of 10,000 sheets /
Under the conditions of the time, solid printing was continuously performed on the surface of the same coated paper as described above using the ink “HIPLUS Plus Veni” manufactured by Toyo Ink Co., Ltd. The number of printed sheets on which the difference in density between the deformed portion and its surroundings disappeared, that is, whether partial deformation was restored, was counted, and the restoring property of the printing blanket was evaluated based on the following criteria.

Good: Restorability is good before the 100th sheet. Δ: 101st to 500th sheets, slightly poor restorability. X: Poor restorability after the 501st sheet. Shock Absorbency Test Each printing blanket was used on the same offset printing machine as in the above-mentioned practical test I, and under the conditions of a printing pressure of 15/100 mm and a printing speed of 10,000 sheets / hour, the surface of the same coated paper as above was applied to Toyo A 70% full screen printing was performed using the ink "HIPLUS Plus Veni" manufactured by Ink Co., Ltd.

Then, it is visually observed whether or not the influence of the impact (improper halftone dot, so-called gear mesh) generated at the time of feeding the gear of the printing machine appears in the printing, and based on the following criteria, the printing blanket is printed. The impact absorption was evaluated. ：: No gear mesh was observed at all, and the shock absorption was good. Δ: Slightly poor shock absorption, which is slightly observed in gears.

X: Poor shock absorption, in which gears can be clearly seen. Table 4 shows the above results. In each column of Table 4, the left side of "/" indicates the evaluation result of the restorability test, and the right side indicates the evaluation result of the shock absorption test. For example, x / △ in the upper left column in the table means that the printing blanket (of Comparative Example 1) has poor resilience (×) and slightly poor shock absorption (性). It shows that there was.

[0062]

[Table 4]

[0063]

As described above in detail, according to the present invention, both of the advantages of the compressible layer having the independent pore structure and the compressible layer having the continuous pore structure are provided, and various disadvantages caused by both disadvantages are obtained. The present invention has a specific function and effect that a printing blanket having excellent characteristics can be provided without causing the problem described above.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an embodiment of a printing blanket according to the present invention, wherein FIG. 1 (a) is a partially enlarged sectional view thereof, and FIG. FIG.

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

FIG. 3 is a view showing another example of the embodiment of the printing blanket of the present invention, wherein FIG. 3 (a) is a partially enlarged sectional view, and FIG. 3 (b) is a perspective view showing the whole. .

[Explanation of symbols]

 1, 2 Printing blanket 12, 23 Compressible layer 14, 24 Surface printing layer CC Independent pore OC Continuous pore

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takamichi Sagawa 41-1, Shimizu, Uozumi-cho, Akashi-shi, Hyogo Prefecture -216548 (JP, A) JP-A-6-344681 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41N 10/00-10/04

Claims (5)

(57) [Claims] 1. The method according to claim 1, further comprising:  With independent pores, Solvent-extractable particles that do not affect rubber
Is dispersed in matrix rubber, and after vulcanizing the rubber, the particles are
Formed by extracting Multi with continuous pores
Printing blanks provided with a porous compressible layer
Kett. 2. The printing blanket according to claim 1, wherein independent pores and continuous pores are randomly mixed in the compressible layer. 3. The compressible layer has a JIS A hardness of 40 to 80 °.
And the porosity of the entire compressible layer is 30 to 60%, and the proportion of independent pores in all the pores contained in the compressible layer is 10%.
2. The printing blanket according to claim 1, wherein the amount is from about 70% by volume to about 70% by volume. 4. The printing blanket according to claim 1, which is in the form of a flat plate. 5. The printing blanket according to claim 1, wherein the printing blanket has a seamless cylindrical shape.