JP2018094857A - Printing blanket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing blanket that can impart good water-absorption and hydrophilic properties to a blanket surface rubber layer without reducing the printability.SOLUTION: A printing blanket 11 has a base layer 12, and a surface print layer 13 that is on the base layer 12 and contains a rubber component. The surface print layer 13 contains lignin derivatives.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printing blanket.

  In offset printing, an image pattern is generally formed by providing a hydrophilic non-image area and an oleophilic image area on a plate, and dampening water and ink are supplied onto the plate to form an image. After that, the image is transferred to the blanket surface and further to the printing medium. At this time, if the water absorption and hydrophilicity of the blanket surface are low, the anti-smudge effect of the non-image area by the fountain solution is low, and the non-image area Part may be soiled. On the other hand, if the amount of dampening water supplied is increased in order to prevent this stain, the emulsification stability of the ink is impaired, resulting in an excessive emulsification state and printability such as a lower transfer density. Further, if the dampening solution is not successfully received by the blanket surface, the dampening solution on the plate is crushed and applied to the print image area, and the printed image becomes unclear. Thus, in order to suppress the supply amount of dampening water and perform printing under proper ink emulsification conditions, the surface rubber of the blanket is required to have water absorption and hydrophilicity in addition to compatibility with ink.

  Conventionally, as one method for imparting hydrophilicity to the blanket surface, for example, a technique of mixing collagen fiber powder into the blanket surface is known (see Patent Document 1). Further, it is generally performed to improve hydrophilicity by irradiating the blanket surface rubber layer with ultraviolet rays to form an oxide layer on the blanket surface rubber layer.

JP-A-6-122289

  However, in the technique of mixing collagen fiber powder into the blanket surface rubber layer, there is a problem that dispersibility is lowered depending on the particle size of the collagen fiber, and the characteristics of the blanket surface vary. Further, when the blanket surface rubber layer is irradiated with ultraviolet rays, there is a problem that the blanket surface rubber layer is cured and printability is deteriorated.

  The present invention has been made in view of the above-described circumstances, and provides a printing blanket capable of imparting good water absorption and hydrophilicity to a blanket surface rubber layer without deteriorating printability. For the purpose.

  In order to achieve such an object, the printing blanket according to the present invention includes a foundation layer and a surface printing layer that is located on the foundation layer and contains a rubber component, and the surface printing layer contains a lignin derivative. It was set as the structure which contains. The lignin derivative is preferably lignin sulfonate or a modified product thereof.

  As another aspect of the present invention, the surface print layer is configured to contain 3 to 30 parts by weight of the lignin derivative with respect to 100 parts by weight of the rubber component contained in the surface print layer. .

  ADVANTAGE OF THE INVENTION According to this invention, the printing blanket which can provide favorable water absorption and hydrophilicity to a blanket surface rubber layer, without reducing printability can be provided.

FIG. 1 is a schematic sectional view showing an embodiment of the printing blanket of 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 the printing blanket of the present invention. In FIG. 1, a blanket 11 of the present invention includes a surface printing layer 13 containing a rubber component on one surface of a base layer 12.

  The base layer 12 constituting the blanket 11 is, for example, a base fabric such as cotton, polyester fiber, polyvinyl alcohol fiber, aramid fiber, polyethylene terephthalate (PET) film, polyphenylene sulfide (PPS) film, polyethylene naphthalate (PEN) film, or the like. It may be a resin film or the like. The thickness of the foundation layer 12 can be appropriately set within a range of 0.2 to 2.8 mm, for example.

  The base layer 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. There 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 constituting the laminate include, for example, nitrile butadiene rubber (NBR), nitrile butadiene isoprene rubber (NBIR), ethylene propylene rubber (EP), ethylene propylene diene rubber (EPDM, EPT), Examples thereof include butyl rubber (IIR), carboxylated NBR (XNBR), polysulfide rubber, and the like. One of these can be used alone, or two or more can be used in combination.

  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 layer 12 and the surface printing layer 13. FIG.

  The surface printing layer 13 constituting the blanket 11 contains a lignin derivative together with a rubber component. As the rubber component contained in the surface printing layer 13, a conventionally known blanket rubber material can be used. For example, nitrile butadiene rubber (NBR), nitrile butadiene isoprene rubber (NBIR), ethylene propylene rubber (EP ), Ethylene propylene diene rubber (EPDM, EPT), butyl rubber (IIR), carboxylated NBR (XNBR), polysulfide rubber, and the like. These can be used alone or in combination of two or more. Can be used.

  The content of the lignin derivative in the surface print layer 13 is 3 to 30 parts by weight, preferably 3 to 27 parts by weight, and more preferably 10 to 20 parts by weight with respect to 100 parts by weight of the rubber component of the surface print layer. be able to. A printing blanket having a surface printing layer containing a lignin derivative within the above range has the effect of imparting good water absorption and hydrophilicity to the blanket surface rubber layer without reducing printability. It is preferable. If the content of the lignin derivative is less than 3 parts by weight, the water absorption effect is low, and if it exceeds 30 parts by weight, the workability during blanket production may be reduced.

  Examples of the lignin derivative include lignin sulfonate or a modified product thereof. Examples of the lignin sulfonate or a modified product thereof include magnesium lignin sulfonate, sodium lignin sulfonate, calcium lignin sulfonate, sodium modified lignin sulfonate, calcium modified lignin sulfonate, and magnesium lignin sulfonate. it can. In addition to the above, partial desulfonated lignin sulfonate and high-purity lignin sulfonate can be mentioned. The lignin sulfonate may contain a reducing saccharide, a sugar-modified product, and an inorganic salt.

  According to the present invention, the blanket surface rubber layer contains the lignin sulfonate which is a lignin derivative as described above or a modified product thereof, and the following effects are expected. First, the lignin derivative has a phenolic hydroxyl group, and the lignin sulfonate has a functional group such as a sulfonic acid group or a carboxylic acid group in addition to the phenolic hydroxyl group. Adsorbs chemically and physically. In addition, lignin derivatives and lignin sulfonates have a surfactant structure with a hydrophobic skeleton such as phenyl groups and alkyl groups and hydrophilic groups such as phenolic hydroxyl groups and sulfonic acid groups, so they have good dispersibility in rubber. In addition, an effect of imparting sufficient water absorption / hydrophilicity to the blanket surface is expected.

  The phenolic structure of lignin derivatives is also included in rosin-modified phenolic resins contained in offset printing inks. This rosin-modified phenolic resin improves the pigment dispersibility of the ink and dissolves in hydrocarbon solvents and oils. It is used for the purpose of improving printing property and improving printability by reacting with a gelling agent. A similar effect is expected for a lignin derivative having a phenol structure, and when added to the blanket surface, in addition to the improvement in water absorption and hydrophilicity, the incidental effect of improving the affinity with inks that cannot be obtained by the prior art. The effect is also expected.

  Such a surface printing 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, a nitrile butadiene rubber (NBR), a nitrile butadiene isoprene rubber (NBIR), an ethylene propylene rubber (EP), or an ethylene propylene diene, in the same manner as the adhesive rubber layer constituting the base material of the laminate structure described above. Examples thereof include rubber (EPDM, EPT), butyl rubber (IIR), carboxylated NBR (XNBR), polysulfide rubber and the like. One of these can be used alone, or two or more can be used in combination. The thickness of the adhesive rubber layer can be set as appropriate.

  The thickness of the surface print layer 13 can be appropriately set within a range of, for example, 0.17 to 0.65 mm, preferably 0.25 to 0.65 mm. Further, the surface printing layer 13 may have a multilayer structure. In this case, at least the outermost surface layer contains a lignin derivative as described above. The thickness of the outermost surface layer in the surface printed 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 printing blanket of the present invention can impart good water absorption and hydrophilicity to the blanket surface rubber layer without deteriorating the printability.

  The above-described embodiment is an exemplification, and the printing blanket of the present invention is not limited thereto. For example, an appropriate amount of a silane coupling agent may be added to the surface printing layer 13. The addition amount of the silane coupling agent can be set as appropriate. The addition amount of the silane coupling agent can be set, for example, in the range of 0.1 to 15 parts by weight, preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the rubber component of the surface print layer 13. An appropriate amount of a silicone additive may be added to the surface print layer 13. The addition amount of the silicone-based additive can be appropriately set. As addition amount of a silicone type additive, it can set in the range of 1-30 weight part with respect to 100 weight part of rubber components of the surface printing layer 13, Preferably it is 2-20 weight part.

<Production of rubber sheet>
A rubber having a thickness of 2 mm was press-vulcanized for 15 minutes at 150 ° C. and a pressure of 5.6 MPa using eight types of rubber compositions (unvulcanized state) of compositions 1 to 8 shown in Table 1 below. Sheets (Sample 1 to Sample 8) were produced.

Abbreviations for the ingredients listed in Table 1 below are as follows. In addition, the numerical value of Table 1 represents the weight part.
Lignin derivative A: Nippon Paper Industries Co., Ltd. Sun Extract (registered trademark) P202
(Calcium lignin sulfonate)
Lignin derivative B: Sun Extract (registered trademark) P321 manufactured by Nippon Paper Industries Co., Ltd.
(Magnesium lignin sulfonate)
・ Lignin derivative C: Nippon Paper Industries Co., Ltd. Sun Extract (registered trademark) P252
(Sodium lignin sulfonate)
・ Lignin derivative D: Pearl Rex (registered trademark) NP manufactured by Nippon Paper Industries Co., Ltd.
(High purity high molecular weight sodium lignin sulfonate)
Lignin derivative E: Nippon Paper Industries Co., Ltd. Pearl Rex (registered trademark) DP
(High-purity modified sodium lignin sulfonate)
-Plasticizer: Polyether ester plasticizer-Vulcanization accelerator A: Dithiocarbamic acid vulcanization accelerator-Vulcanization accelerator B: Sulfenamide vulcanization accelerator

<Evaluation of rubber sheet>
(Measurement method and conditions of volume change rate)
From each of the rubber sheets (samples 1 to 8) having a thickness of 2 mm, test pieces (samples 1 to 8) were prepared using die cutting, and their volumes were measured with a hydrometer.
Each of the test pieces (samples 1 to 8) was put in a container containing tap water, immersed in water at room temperature for 3 days, taken out from the container, and their volume was measured with a hydrometer.
From the volume of the test piece (samples 1 to 8) before dipping in tap water and the volume of the test piece (samples 1 to 8) after dipping, the volume change rate (%) with respect to the original volume of each test piece is calculated. Calculated. The results are shown in Table 2.

From the results in Table 2, the rubber sheet containing lignin derivative (Sample 2 to Sample 8) has a larger volume change rate than the rubber sheet (Sample 1), and has improved water absorption and hydrophilicity. Confirmed to do.
When the volume change rate is 4% or more, good water absorption / hydrophilicity as a blanket is obtained, and when the volume change rate exceeds 15%, the water absorption / hydrophilic effect does not change greatly.
Further, from the results of the rubber sheets (Sample 4 to Sample 6), it was confirmed that the volume change rate increased as the content of the lignin derivative (here, lignin derivative C) was increased.
Furthermore, from the results in Table 2, it was confirmed that the degree of improvement in water absorption and hydrophilicity can be adjusted by appropriately selecting the lignin derivative to be used.

<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 layer having a thickness of 1.6 mm was obtained.

  Of the compositions 1 to 8 shown in Table 1, the first layer constituting the base layer prepared from the three types of rubber pastes prepared from the composition 1, the composition 4 and the composition 6 as described above. It applied to the base fabric as a cloth and dried. Thereafter, the can was vulcanized at 140 ° C. for 7 hours to form a surface layer, and the surface layer was polished to prepare three blankets (samples 9 to 11).

<Evaluation of blanket>
Each of the produced blankets (samples 9 to 11) was subjected to an ink transfer test, and the ink transfer density transferred to the paper was measured using a reflection densitometer (QUIKdens manufactured by X-Rite). The higher this concentration, the better the ink transferability. The measurement results are shown in Table 3 below.

  From the results in Table 3, the blanket containing the lignin derivative in the surface print layer (Sample 10 and Sample 11) did not show a decrease in the ink transfer density as compared with the blanket (Sample 9), and the water absorption of the surface print layer. -It was confirmed that a decrease in ink transferability was prevented while hydrophilicity was improved. In the preparation of the rubber composition, the dispersibility of the added lignin derivative was good as a result of visual observation.

  It can be used for printing using a blanket.

11 ... Blanket 12 ... Base layer 13 ... Surface printed layer

Claims (3)

A base layer, and a surface printing layer located on the base layer and containing a rubber component,
The printing blanket, wherein the surface printing layer contains a lignin derivative. The printing blanket according to claim 1, wherein the lignin derivative is lignin sulfonate or a modified product thereof. The said surface printing layer contains 3-30 weight part of said lignin derivatives with respect to 100 weight part of said rubber components contained in this surface printing layer, The Claim 1 or Claim 2 characterized by the above-mentioned. Blanket for printing.

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