JP2015171779A - blanket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blanket for off-set printing having high wear resistance of a surface rubber layer and also excellent durability and printability.SOLUTION: A blanket 11 at least comprises base material 12, and a surface rubber layer 13 on the base material 12. The surface rubber layer 13 comprises silicone-based additive in the range of 0.5-14 wt.%.

Description

  The present invention relates to a blanket for printing, and more particularly to a blanket having a surface rubber layer excellent in wear resistance.

  In offset printing, generally, dampening water and ink are supplied to a cylinder equipped with a blanket through a plate, and then the printing material supplied between the blanket cylinder and the impression cylinder or between the opposite blanket cylinders is printed. Printing is performed by transferring ink on the blanket. The blanket used for offset printing has a structure in which a surface rubber layer is laminated on a base material, and the surface rubber layer is oil resistant, for example, nitrile butadiene rubber (NBR), considering contact with ink. Excellent ingredients are blended. In addition to NBR, butyl rubber (IIR), polysulfide rubber (thiocol (registered trademark)), carboxylated NBR (XNBR), nitrile butadiene isoprene rubber (NBIR), and the like are used. Ethylene propylene rubber (EP, EPDM) and the like are also used. In addition, a solid type that does not include a compressed layer and a compressible type that includes a compressed layer are used. However, even when a compressible type substrate is used, the surface rubber layer of the blanket periodically comes into contact with the printing plate and the printing material, so that the surface rubber layer is worn and the printing durability is reduced. There was a problem.

  Conventionally, in order to improve the wear resistance of printing blankets, blanket with reinforcing agent such as calcium carbonate, magnesium carbonate, magnesium silicate, carbon black added to the surface rubber layer, and silane coupling agent to form the surface rubber layer A blanket and the like are also developed (Patent Documents 1 to 4).

JP-A-8-58265 Japanese Patent Laid-Open No. 11-91260 JP 2002-254854 A JP 2004-209927 A

However, when a reinforcing agent is added to the surface rubber layer or a silane coupling agent is used in combination, there is a problem that the hardness of the surface rubber layer becomes too high and adversely affects printability. In addition, the combined use of the silane coupling agent has a problem that the pasting processability is deteriorated in the formation of the surface rubber layer using the pasty unvulcanized rubber, or the uncured rubber is prematurely gelled. It was.
The present invention has been made in view of such circumstances, and an object thereof is to provide a blanket for offset printing having high wear resistance of a surface rubber layer and having excellent durability and printability. .

  In order to achieve such an object, the blanket of the present invention comprises a base material and a surface rubber layer located on the base material, and the surface rubber layer contains 0.5 to 14 weights of a silicone-based additive. % In the range.

The silicone additive is configured to be a graft copolymer of silicone and acrylic.
The graft copolymer was a graft copolymer of a polyalkylsiloxane and a methacrylic acid alkyl ester / methacrylic acid hydroxyalkyl ester copolymer.
The silicone additive was configured to be high molecular weight silicone.

The high molecular weight silicone was configured to contain 65% by weight or more of siloxane as a main component.
The high molecular weight silicone was configured to contain silica as an accessory component.
The surface rubber layer includes at least one of nitrile butadiene rubber (NBR), ethylene propylene rubber (EP, EPDM), nitrile butadiene isoprene rubber (NBIR), butyl rubber (IIR), carboxylated NBR (XNBR), and polysulfide rubber. It was set as the structure which contains.

  The blanket of the present invention has high wear resistance in offset printing, has excellent durability, and exhibits excellent printability.

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

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an embodiment of a printing blanket according to the present invention. In FIG. 1, a blanket 11 of the present invention includes a surface rubber layer 13 on one surface of a substrate 12.
The base material 12 constituting the blanket 11 is a base fabric such as cotton, polyester fiber, polyvinyl alcohol fiber or aramid fiber, resin such as PET (polyethylene terephthalate) film, PPS (polyphenylene sulfide) film, PEN (polyethylene naphthalate) film, etc. It may be a film or the like. The thickness of the base material 12 can be appropriately set within a range of 0.22 to 2.8 mm, for example.

The substrate 12 may be a laminate in which a plurality of base fabrics are laminated via an adhesive rubber layer, and a compression layer is interposed between the base fabrics constituting such a laminate. It may be. The number of base fabrics constituting the laminate can be set as appropriate, and can be set, for example, at about 2 to 5 sheets.
Examples of the rubber component of the adhesive rubber layer include, for example, nitrile butadiene rubber (NBR), ethylene propylene rubber (EP, EPDM), nitrile butadiene isoprene rubber (NBIR), butyl rubber (IIR), carboxylated NBR (XNBR), many A sulfurized rubber etc. can be mentioned, These 1 type can be used individually or in combination of 2 or more types. The thickness of the adhesive rubber layer can be set as appropriate.

In addition, as the material of the compression layer, a material used in a conventional blanket can be used. For example, a multilayer fabric, a nonwoven fabric, or a foam structure sheet containing hollow structure fine particles in a rubber material, A foamed structure sheet (sponge rubber) or the like provided with a hollow structure with a foaming agent or the like can be used. In addition, a compression layer is not limited to what is interposed between base fabrics, You may be located between the base material 12 and the surface rubber layer 13. FIG.
The surface rubber layer 13 constituting the blanket 11 contains a blanket surface rubber material and a silicone-based additive.

As the surface rubber material for the blanket, a conventionally known blanket rubber material can be used, for example, nitrile butadiene rubber (NBR), ethylene propylene rubber (EP, EPDM), nitrile butadiene isoprene rubber (NBIR), butyl rubber. (IIR), carboxylated NBR (XNBR), polysulfide rubber and the like can be mentioned, and one of these can be used alone or in combination of two or more.
The content of the silicone-based additive in the surface rubber layer 13 is preferably in the range of 0.5 to 14% by weight. When the content of the silicone additive is less than 0.5% by weight, the surface rubber layer 13 may not exhibit high wear resistance, which is not preferable. On the other hand, if the content of the silicone-based additive exceeds 14% by weight, the ink swells and the effect of the previous printing plate may remain when the printing plate is switched, which is not preferable.
Examples of such silicone-based additives include a graft copolymer of silicone and acrylic, high molecular weight silicone, and the like.

  Examples of the graft copolymer of silicone and acrylic include, for example, a graft copolymer of a polyalkylsiloxane and an alkyl methacrylate / methacrylic acid hydroxyalkyl ester copolymer. Content in the surface rubber layer 13 Is in the range of 0.5 to 14% by weight as described above, preferably 0.5 to 10% by weight, more preferably 1 to 10% by weight. Examples of such a graft copolymer of silicone and acrylic include Charine R-170S and Charine R-170 manufactured by Nissin Chemical Industry Co., Ltd.

Examples of the high molecular weight silicone include a silicone containing 65% by weight or more, preferably 65 to 75% by weight of siloxane as a main component, and the content in the surface rubber layer 13 is as described above. Thus, the range is 0.5 to 14% by weight, preferably 0.5 to 5% by weight, and more preferably 2 to 5% by weight. This high molecular weight silicone may contain silica as an auxiliary component in the range of 25 to 35% by weight. Examples of such high molecular weight silicones include GENIOPLAST PELLET S manufactured by Asahi Kasei Wacker Silicone Co., Ltd.
Such a surface rubber layer 13 may be formed directly on one surface of the substrate 12 or may be formed via an adhesive rubber layer. The adhesive rubber layer is, for example, nitrile butadiene rubber (NBR), ethylene propylene rubber (EP, EPDM), nitrile butadiene isoprene rubber (NBIR), butyl rubber, in the same manner as the adhesive rubber layer constituting the base material of the laminate structure described above. (IIR), carboxylated NBR (XNBR), polysulfide rubber, and the like can be used, and one of these can be used alone or in combination of two or more, and the thickness is appropriately set. Can do.

  The thickness of the surface rubber layer 13 can be appropriately set, for example, in the range of 0.17 to 0.65 mm, preferably 0.25 to 0.65 mm. Further, the surface rubber layer 13 may have a multilayer structure. In this case, at least the outermost surface layer contains a silicone additive in the range of 0.5 to 14% by weight as described above. . The thickness of the outermost surface layer in the surface rubber layer 13 having such a multilayer structure can be appropriately set within a range of 0.05 to 0.64 mm, for example.

Such a blanket of the present invention has high wear resistance in offset printing, has excellent durability, and has a hardness in an appropriate range, and thus can exhibit excellent printability. In the blanket manufacturing process of the present invention, the pasting processability in the formation of the surface rubber layer using the paste-like unvulcanized rubber is stable, and further, the deterioration of the paste state of the unvulcanized rubber is suppressed. can do. Thereby, it is possible to stably form a surface rubber layer having high wear resistance and exhibiting excellent durability and printability.
The above-described embodiments are examples, and the blanket of the present invention is not limited to these.

Next, an Example is shown and this invention is demonstrated further in detail.
<Production of blanket>
An NBR rubber paste for a compression layer containing acrylic hollow fine particles (organic thermal expansion microballoon) was applied to one surface of the base fabric as the second layer fabric and dried. Further, an NBR rubber paste for the adhesive rubber layer was applied to one surface of the base fabric as the first layer fabric and dried. Next, the pasted surfaces of the two base fabrics were bonded together.

  Next, the NBR rubber paste for the adhesive rubber layer was applied to the other surface of the base fabric as the second layer fabric bonded as described above and dried. Further, an NBR rubber paste for the adhesive rubber layer was applied to one surface of the base fabric as the third layer fabric and dried. Next, the pasted surface of the base fabric as the second layer fabric and the pasted surface of the base fabric as the third layer fabric were bonded together. Thereafter, vulcanization is performed by pressurization and heating, and a first layer fabric to a third layer fabric are provided, and a compression layer is provided between the first layer fabric and the second layer fabric. A base material having a thickness of 1.6 mm was obtained.

  On the other hand, 17 kinds of rubber compositions (unvulcanized state) for the surface rubber layer of Composition 1 to Composition 17 shown in Table 1 and Table 2 below were dissolved in a mixed solvent of toluene and MIBK, A surface rubber paste was prepared. The 17 types of surface rubber paste were each applied to a base fabric as a first layer fabric constituting the base material produced as described above and dried. Thereafter, the can was vulcanized at 140 ° C. for 7 hours to form a surface rubber layer, and the surface rubber layer was polished to prepare blankets (Sample 1 to Sample 17).

Abbreviations of the blending components described in Tables 1 and 2 below are as follows. In addition, the numerical value of Table 1 and Table 2 represents the weight part.
Plasticizer A: Polyether ester plasticizer Plasticizer B: Polyester plasticizer Plasticizer C: Phosphate ester plasticizer Vulcanization accelerator A: Dithiocarbamic acid vulcanization accelerator Vulcanization accelerator B: Sulfenamide vulcanization accelerator-Silicone additive A: Graft copolymer of silicone and acrylic (R170S)
・ Silicone-based additive B: High molecular weight silicone (GENIOPLAST)
The composition 1 was a conventional blanket surface rubber layer composition that had good printability but had no measures to improve abrasion resistance.

<Evaluation of blanket>
For each blanket (Sample 1 to Sample 17) produced as described above, the hardness Hs, tensile strength TB, and Taber abrasion index of the surface rubber layer were measured by the following methods and conditions, and the results are shown in Table 3 below. It was. For each blanket (Sample 1 to Sample 17), a previous plate remaining test was performed under the following conditions, and the evaluation results are shown in Table 3 below. Furthermore, the applicability (glue processability) of the surface rubber layer composition and the stability (glue state) of the surface rubber layer composition were visually observed and evaluated according to the following criteria. These results are shown in Table 3 below.

(Measurement method and conditions of hardness Hs)
Using the surface rubber composition, press vulcanization was performed at 150 ° C. and a pressure of 5.6 MPa for 15 minutes to produce a rubber sheet having a thickness of 2 mm, and the hardness Hs was measured. The measurement was based on JISK6253, and durometer type A was used.

(Measurement method and conditions of tensile strength TB)
Using the surface rubber composition, press vulcanization was performed at 150 ° C. and a pressure of 5.6 MPa for 15 minutes to produce a rubber sheet having a thickness of 2 mm, and the tensile strength TB was measured. The measurement was based on JISK6251 and dumbbell No. 3 was used.

(Taber wear index measurement method and conditions)
Using the produced blanket, a Taber abrasion test was performed in accordance with JISK6264 with a load of 500 g and an abrasion wheel H-18.

(Previous version remaining test methods and conditions)
An ink holding jig is closely attached to the surface rubber layer of the produced blanket, and about 10 mm in depth is put inside, and the ink is retained at 50 ° C. for 5 days. Then, the ink is quickly and completely removed, and then an ink transfer test is performed. The density difference between the contact part and the non-contact part with the ink holding jig was evaluated.
(Evaluation criteria)
○: The density difference is small.
Δ: The density difference is slightly large and is slightly affected by the previous version, but at a practical level.
×: The density difference is large and affected by the previous version.

(Evaluation criteria for pasting processability / glue state)
○: No streaking or stringing occurs, and no gelation is observed.
Δ: Some streaking and stringing occur, and gelation is also observed.
×: Streaking and stringing occur and premature gelation occurs.

  As shown in Table 3, a blanket (Sample 3 to Sample 7, Sample 14) containing a graft copolymer of silicone and acrylic (silicone-based additive A) in a predetermined content range on the surface rubber layer, Alternatively, the blanket (sample 10 to sample 12) containing high molecular weight silicone (silicone-based additive B) in a predetermined content range has a hardness Hs of the surface rubber layer of less than 60, and the result of the previous plate remaining test. Has excellent printability similar to that of a non-wear-resistant blanket (Sample 1), has a Taber wear index of less than 80, and a tensile strength TB of 4.5 MPa or more, and has high wear resistance. It was confirmed that it was excellent in durability. Moreover, it was confirmed that these blankets also have good pasting workability / glue state at the manufacturing stage.

  On the other hand, the content of the silicone / acrylic graft copolymer (silicone additive A) in the surface rubber layer is slightly low, or the content of high molecular weight silicone (silicone additive B) is low. Slightly less blanket (Sample 9) has improved wear resistance compared to the conventional blanket (Sample 1) with poor wear resistance and is at a practical level, but the above blanket (Sample 3 to Sample 7) In comparison, the Taber abrasion index was high (about 110 to 120), which was slightly insufficient in terms of improving the abrasion resistance.

  In addition, the blanket (sample 8) in which the content of the graft copolymer of silicone and acrylic (silicone additive A) in the surface rubber layer is excessive, or the content of high molecular weight silicone (silicone additive B) In the blanket (Sample 13) having an excessive amount, although the printability was at a practical level, the density difference in the remaining test of the previous plate was slightly large and was slightly affected by the previous plate.

  Further, even when polysulfurized rubber is contained together with NBR as the rubber material for the surface rubber layer, a blanket (sample 14) containing a graft copolymer of silicone and acrylic (silicone-based additive A) and a blanket containing no ( From the comparison with Sample 15), the effect of improving the abrasion resistance by containing the silicone-based additive was clear.

  Further, in the blankets (Sample 16 and Sample 17) in which the silica content in the surface rubber layer is increased and the silane coupling agent is used, the Taber abrasion index is almost good, but the hardness Hs of the surface rubber layer is high. It was confirmed that printability could be adversely affected.

  It can be used for printing using a blanket.

11 ... Blanket 12 ... Base material 13 ... Surface rubber layer

Claims (7)

  A blanket comprising: a base material; and a surface rubber layer positioned on the base material, wherein the surface rubber layer contains a silicone additive in a range of 0.5 to 14% by weight.   The blanket according to claim 1, wherein the silicone-based additive is a graft copolymer of silicone and acrylic.   The blanket according to claim 2, wherein the graft copolymer is a graft copolymer of a polyalkylsiloxane and a methacrylic acid alkyl ester / methacrylic acid hydroxyalkyl ester copolymer.   The blanket according to claim 1, wherein the silicone-based additive is high molecular weight silicone.   The blanket according to claim 4, wherein the high molecular weight silicone contains 65% by weight or more of siloxane as a main component.   The blanket according to claim 5, wherein the high molecular weight silicone contains silica as an accessory component.   The surface rubber layer is made of at least one of nitrile butadiene rubber (NBR), ethylene propylene rubber (EP, EPDM), nitrile butadiene isoprene rubber (NBIR), butyl rubber (IIR), carboxylated NBR (XNBR), and polysulfide rubber. The blanket according to any one of claims 1 to 6, wherein the blanket is contained.

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