JP2007331251A - Inking rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inking rubber roller which is substituted for a conventional NBR rubber roller that has no sufficient strength, though it is formed of an oil-resistant rubber, which is constituted of two rubber layers out of which the outer layer is made of a urethane rubber layer having high stiffness of 0-60 according to JIS A standard and the inner layer of a rubber layer having low stiffness, of which the surface layer is thus made to have sufficient strength and to be hardly flawed, while the rubber layer is made to have the stiffness of 25-35 according to the JIS A standard, as a whole, and which has thus a necessary pliability, a soft touch and an excellent inking performance. <P>SOLUTION: The rubber of this inking rubber roller is constituted of the two layers, the outer layer 23 and the inner layer 24, and the rubber layer of the outer layer 24 is formed of the urethane rubber having the stiffness of 40-60 according to the JIS A standard, while the stiffness of the whole rubber layer is made 25-35 according to the same standard. The tensile strength of the rubber of the outer layer 23 is 20 MPa or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink-applied rubber roller, and more particularly to an ink-applied rubber roller used in a newspaper printer.

  Today, lithographic offset printing is widely used for newspaper printing. FIG. 3 shows an example of a main part of a printing machine used for lithographic offset printing of newspapers. In FIG. 3, reference numeral 1 denotes a plate cylinder. Ink supplied from the ink tank 2 is supplied to the peripheral surface of the plate cylinder 1.

  Ink is supplied from the ink tank 2 by the ink source roller 3 to the peripheral surface of the plate cylinder 1 by the ink application rubber roller 10 through the ink delivery roller 4 and the doctor roller 5. This is done so that the required amount of ink is applied to the image area of the plate. Reference numeral 14 denotes a swim roller.

  The plate cylinder 1 rotates while being in contact with the blanket cylinder 11, and the ink in the image area of the plate attached to the circumferential surface of the plate cylinder 1 is transferred to a rubber blanket attached to the circumferential surface of the blanket cylinder 11. . The image area ink transferred to the rubber blanket is then printed on the newspaper 13 using the impression cylinder 12.

  The ink-applied rubber roller 10 used in such a printing machine is made by winding rubber around an aluminum alloy or iron core and vulcanizing it, and further polishing the rubber surface with a polishing machine. As the rubber of the rubber roller used here, nitrile rubber (NBR), which is oil-resistant rubber, is overwhelmingly widely used because the ink is usually oil-based ink.

  However, newspaper printing is strongly demanded for high-speed printing due to its character, and therefore, the printing press is used under severe conditions, and accordingly, the ink-applied rubber roller is used in an extremely severe environment. For this reason, it has often been pointed out that the ink-fitted rubber roller has a problem that the surface of the roller is damaged in a short period of time by a printing plate. When the rubber roller was scratched, ink was not deposited on the scratched portion, and printing was performed with a streak-like mark remaining on the printing surface.

  In particular, if a level difference occurs even at the joining portion of the plate attached to the surface of the plate cylinder and there is an uneven state, the surface of the inking rubber roller hitting the edge portion of the uneven plate is likely to be damaged. In newspaper printing, a plate is made for each newspaper sheet and is fixed to the plate cylinder. These plates are attached to the plate cylinder with an interval corresponding to the white blank portion provided in the center of the spread of the newspaper, and printed on one double-page (two pages) printing paper. Is what has been done. The printed newspaper is folded into two, centering on the white background in the center, and is subscribed.

  In newspaper printing, there is a slight level difference at the edge of the plate, which is the junction between the plate and the plate attached to the plate cylinder, so that the inked rubber roller that contacts this part may be damaged. Something happened. For this reason, there has actually been a situation where printing actually has a problem with printing. Fortunately, however, this part is the central part of the newspaper where nothing is printed, so far this has not been particularly problematic. For this reason, even if the inked rubber roller is slightly scratched at the place where it contacts the edge of the joint between the plate and the plate, it can be used as it is. Therefore, conventionally, the life of the ink-fitted rubber roller has been long to some extent.

  Recently, however, many large advertising articles spanning two pages in a spread state have been published on newspapers. In the case of such a large advertisement including the center portion of the spread, printing is performed also on the portion of the center portion of the spread that has been previously unprinted white. In such a case, if an ink-fitting rubber roller with a slight scratch is used at the edge of the joint between the plate and the plate of the ink-fitting rubber roller, the ink does not get on this part, and a streak is formed in the vertical direction on the paper surface. The traces will remain. When such printing is performed, the advertisement paper surface is improperly printed, causing problems.

  Therefore, recently, in order to prevent such a situation from occurring, the ink-applied rubber roller is frequently replaced so that the ink-applied rubber roller is not damaged at the edge of the joint between the plate and the plate. This prevents the streak-like traces from appearing even in the advertisement part in the center of the spread.

  However, the ink-printed rubber roller for newspaper printing used under severe conditions is exhausted even if it is not, and has been forced to be replaced in a short period of time in January. In addition, the life of ink-fitted rubber rollers will become increasingly shorter and cost will increase when new replacements are made so as to avoid streak-like problems at the center of the spread as recently. It was.

  Conventionally, many proposals have been made for ink-applied rubber rollers of printing presses. The ink-applied rubber roller of a newspaper printer uses a doctor blade that is pressed against the ink roller, but the deformation of the rubber roller that is received when the ink is pressed concentrates locally, making it difficult to adjust the thickness of the ink film stably. There has been a problem in the past. In order to solve this problem, an ink-fitted rubber roller having a two-layer structure in which an outer layer is a hard elastic rubber and an inner layer is a soft elastic rubber is known (for example, see Patent Document 1).

There is also known an ink form roller in which the rubber hardness of a single layer of urethane rubber formed on a roller core is 40 ° to 45 ° when the single layer surface temperature is 25 ° C. (For example, refer to Patent Document 2). Furthermore, in order to improve the printing performance by lowering the hardness than conventional polyurethane rollers and to produce polyurethane rollers that are not easily affected by the solvent of the ink, the polyester for polyurethane elastomer is heated and a plasticizer is injected. Stirring, further injecting curing agent, stirring and dehydrating under reduced pressure, then injecting into mold, heating and releasing after sulfidation, plasticizer is diethyl phthalate, curing agent is tolylene A method for producing a polyurethane roller for a printing press containing an isocyanate is known (for example, see Patent Document 3). Further, as a printing rubber roll excellent in solvent resistance, a printing roll made of a polyurethane elastomer, an aliphatic hydrocarbon polymer polyol in which an isocyanate group-containing prepolymer has an organic polyisocyanate and a side chain aliphatic hydrocarbon group A printing roll which is an isocyanate group-containing prepolymer obtained by reacting with the above is known (for example, see Patent Document 4).
JP 62-51453 A (Claims (1), (2)) JP-A-10-272765 (Claim (1)) JP 05-301335 A (Claims) JP 2004-98359 A (Claims)

  However, in Patent Document 1 described above, the deformation of the rubber roller due to the pushing of the doctor blade is concentrated in the vicinity of the pushing of the blade, and the rubber roller is greatly dented only near the pushing of the blade, so that it is difficult to stably adjust the thickness of the ink film. In order to avoid the occurrence of unevenness in thickness, it was not intended to extend the life of the ink form roller. For this reason, even in this prior art, the ink-attached rubber roller uses an oil-resistant synthetic rubber nitrile butadiene rubber (NBR) because oil-based ink is used in newspaper printing. NBR is a representative oil-resistant rubber and is low in price, but it is not strong enough as an ink-fitting rubber roller for newspaper printing used under harsh conditions, and the problem is that the surface is easily scratched after a short period of use. there were.

  In addition, since Patent Document 2 uses urethane rubber as a single layer and the rubber hardness is 40 to 45 degrees when the temperature is 25 ° C., the surface layer has a required hardness, but the entire rubber layer is too hard. The flexibility of the roller as a whole was insufficient and the ink performance was not good, and the ink could not be smoothly delivered to the printing plate. Further, since Patent Document 3 is a urethane rubber roller having a hardness (Shower A) of 30 degrees or 20 degrees, it is surely satisfactory for improving ink performance, but is insufficient in terms of strength. there were. In addition, Patent Document 4 is excellent in solvent resistance, but has a hardness of 70 to 80 degrees and lacks flexibility and cannot be used as an ink form roller applied to high-speed printing such as newspaper printing.

  In this way, all of the ink form rollers using urethane rubber are high in hardness and lack in flexibility and ink performance is insufficient. Ink transfer is not performed smoothly. However, the ink performance is good, but the strength is insufficient to prevent the occurrence of scratches on the rubber roller surface.

  This invention replaces a conventional NBR rubber roller which is an oil-resistant rubber but has insufficient strength, and the surface layer is a urethane rubber layer having a hardness of 40-60 in accordance with the high hardness JISA standard, and the inner layer is a rubber layer having a low hardness. As the rubber layer of the layer, the surface layer has sufficient strength to make it difficult to be scratched, and the rubber layer as a whole has the necessary flexibility with a hardness of 25 to 35, and has a soft touch and good ink performance. Try to get a roller.

  This invention is an inking rubber roller, the rubber of the rubber roller is composed of two layers, a surface layer and an inner layer, and the surface rubber layer is urethane rubber having a hardness of 40 to 60 in terms of JISA standard hardness. The total hardness is 25 to 35 in the same standard hardness and the rubber strength of the surface layer is 20 MPa or more, and the rubber hardness of the inner layer is JISA standard hardness. The inked rubber roller according to claim 1 (Claim 2) and the thickness of the surface rubber layer are 3 mm or less. The inked rubber roller according to Claim 1 or Claim 2 (Claim 2). 3).

  According to the present invention, since the rubber layer is composed of two layers and the surface rubber layer is made of high-hardness urethane rubber, scratches due to the edge of the plate are significantly less likely to occur than in a conventional ink-fitted rubber roller. Moreover, low hardness rubber is used for the inner rubber layer, and the hardness of the entire rubber layer is set to 25 to 35 according to JISA standard, so that the whole can have the same flexibility as a conventional rubber roller. A rubber roller with good ink characteristics can be obtained by soft touch. Furthermore, because it uses urethane rubber, it has oil resistance, and because it has a tensile strength of 20 MPa or more, it can sufficiently withstand severe newspaper printing and withstand long-term use compared to conventional ink-fitted rubber rollers. Can be an inked rubber roller.

  FIG. 1 is a side view of an ink-attached rubber roller for a newspaper printing machine according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a central portion of the rubber roller. In FIG. 1, 20 is an ink-fitting rubber roller, 21 is an iron core, and 22 is a rubber layer. As shown in FIG. 2, the rubber layer 22 is composed of two layers, a surface layer 23 and an inner layer 24.

  The rubber used for the surface layer 23 is urethane rubber, and the hardness of the rubber layer of the surface layer 23 is 40-60 in terms of JISA standard hardness. By setting the hardness of the surface rubber layer within this range, the occurrence of scratches on the surface of the ink-fitted rubber roller can be greatly reduced even in severe newspaper printing. As a result, even if there is a slight level difference at the junction between the plate attached to the plate cylinder and the plate, the ink form roller hitting this portion will not be damaged, and printing will be performed at this portion. Can be prevented.

  If the rubber hardness of the surface layer 23 is less than 40 in the JISA standard, the hardness is insufficient and the effect of reducing the occurrence of scratches on the roller surface cannot be expected sufficiently, but if the rubber hardness exceeds 60, the surface rubber is too hard and flexible. Ink properties are deteriorated, such as insufficient ink supply and proper ink supply. The more preferable range of the hardness of the surface rubber is 45 to 55 according to the JISA standard. Furthermore, the tensile strength of the surface rubber layer is set to 20 MPa or more to maintain the strength of the rubber roller. Furthermore, since urethane rubber is oil resistant, it is oil resistant to oil-based inks.

  The inner layer rubber is usually NBR, but may be urethane rubber. The hardness of the rubber layer of the inner layer is 20 or less according to the JISA standard. As a result, the hardness of the entire rubber layer including the surface layer and the inner layer is in the range of 25 to 35 according to the JISA standard. If the hardness of the entire rubber layer is less than 25 in the JISA standard, the rubber layer is too soft to supply ink properly, and a good ink-fitted rubber roller cannot be obtained. On the other hand, even if the hardness of the entire rubber layer exceeds 35 in the JISA standard, the rubber layer is too hard and ink deposition is not performed properly.

  In this invention, the surface layer rubber is urethane having a hardness of 40 to 60 according to JISA standard, and the surface layer with the entire rubber layer having a hardness of 25 to 35 uses a rubber roller. In addition, it is possible to prevent ink from being generated, and the rubber layer as a whole is flexible so that ink can be applied properly.

  NBR, which has been widely used in the past, has oil resistance and is extremely excellent as an ink-attached rubber roller for oil-based ink. However, NBR was weak in strength and severely damaged when used as an ink-fitting rubber roller for severe newspaper printing. In newspaper printing, which requires increasingly severe use, the only way to withstand these conditions with an NBR rubber roller is to greatly increase the hardness of the rubber to 70-80 according to the JISA standard. However, when the hardness of the rubber roller is set to such a high value, the rubber has lost a great deal of flexibility, and cannot be used as a rubber for an inking roller.

  It is said that the hardness of the rubber of the ink-fitting rubber roller is preferably 25 to 40 according to the JISA standard, and the upper limit is set to 60 at the maximum, so NBR with a hardness of 70 to 80 according to the JISA standard is an ink-fitting rubber. It could not be used as roller rubber. For this reason, conventionally, oil-resistant rubber NBR is used and the hardness is used as 25 to 40 according to the JISA standard, and the problem of occurrence of surface damage is solved by frequently replacing the rubber roller. That's what I have done.

  On the other hand, this invention uses hard urethane rubber having a hardness of 40 to 60 according to JISA standard as the surface layer rubber to prevent the surface of the rubber roller from being scratched and to harden the entire rubber layer. A rubber roller having a thickness of 25 to 35 is used, and the rubber layer has flexibility as a whole and has good ink characteristics.

  Furthermore, in the present invention, the tensile strength of the rubber is set to 20 MPa or more, preferably 40 to 50 MPa, so that sufficient strength can be provided even in newspaper printing in which high-speed printing is performed.

  The rubber roller of the present invention can be produced by a usual method. For example, a thin NBR sheet with a hardness of 20 or less according to JISA standard is wound on a shaft of iron, aluminum, etc., and heated and cured with a roll diameter of about 10 mm to create a rubber roller intermediate product and its surface Polish and smooth. This rubber roller intermediate product is put into a mold, and then a urethane injection solution is injected into the mold and heated. Thereafter, the mold is removed and the surface of the roller is polished to obtain a final product.

(Example)
An NBR sheet having a thickness of 2 mm and a hardness of 20 degrees was laminated on an iron core having a diameter of 120 mm and a length of 1600 mm, and this was heated and cured in a can to produce a rubber roll intermediate product. The surface of this rubber roller intermediate product was polished to obtain a smooth NBR roller having a diameter of 137 mm. The NBR roller was placed in a mold, and then a urethane rubber liquid was poured into the mold and heated with a vulcanizing can. Thereafter, the mold was removed, and the surface of the roller was polished to obtain a diameter of 140 mm to obtain an ink-attached rubber roller having a urethane outer layer.

  The following experiment was conducted to examine the performance of the ink form roller of this example. A rubber roller having a diameter of 125 mm and a length of 200 mm, which is composed of the same two layers as described above and whose surface layer is made of urethane having a thickness of 1.5 mm, was tested with a testing machine shown in FIG. FIG. 4 shows a rubber roller 30 as a center, with a metal roller 31 on one side and another metal roller 32 on the opposite side so as to face the object. Further, the metal roller 32 is mounted on a plate cylinder used for newspaper printing by cutting it into a plate cylinder with a width of 50 mm. The nip width between the metal roller 31 and the rubber roller 30 and the nip width between the rubber roller 30 and the other metal roller 32 were 8 mm.

  In this state, the metal roller 31 rotated in the direction of the arrow at a peripheral speed of 540 m / min, and the metal roller 32 at a peripheral speed of 550 m / min. FIG. 5 is a photograph showing a rubber roller in which urethane rubber is formed on the surface layer, (A) is a photograph showing the surface of the rubber roller, and (B) is a micrograph (200 × magnification) showing the surface of the rubber roller enlarged. It is. As a comparative example, the same rubber roller as described above was made of NBR rubber, and the same test as above was performed. FIG. 6A is a photograph showing the NBR rubber roller, and FIG. 6B is a photomicrograph (magnification 200 times) showing an enlarged surface of the rubber roller.

  FIG. 7 is a graph of the image data of irregularities caused by scratches on the surface of each rubber roller shown in FIGS. 5 (B) and 6 (B). In FIG. 7, 1 is a urethane roller according to an embodiment of the present invention, and 2 is an NBR rubber roller. As is apparent from this, the rubber roller of the present invention did not show any damage due to the edge of the printing plate. In contrast, it can be seen that the rubber roller using NBR is greatly damaged by the edge of the printing plate.

The side view of the rubber roller of one Example of this invention. Sectional drawing of the rubber roller which becomes this invention. Explanatory drawing which shows schematically the principal part of the ink form mechanism of a newspaper printing machine. Explanatory drawing which shows the structure of the rotation tester of a rubber roller. BRIEF DESCRIPTION OF THE DRAWINGS It is a front view of the rubber roller which provided the same urethane as the Example of this invention on the surface layer, (A) is a front view of a roller, (B) is the microscope (200 times magnification) photograph which expanded and showed the rubber roller surface. It is a front view of a NBR rubber roller, (A) is a front view of a roller, (B) is a microscope picture (magnification 200 times) which expanded and showed the rubber roller surface. It is the figure which wrote together the image data of the unevenness | corrugation by the damage | wound of the surface of the rubber roller which provided urethane on the surface layer, and the rubber roller of NBR independent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plate cylinder, 2 ... Ink form roller, 3 ... Ink former roller, 4 ... Ink delivery roller, 5 ... Doctor roller, 10,20 ... Ink form roller, 14 ... Swim-on roller, 11 ... Blanket cylinder, 12 ... Pressure A barrel, 13 ... newspaper, 21 ... iron core, 22 ... rubber layer, 23 ... surface layer, 24 ... inner layer, 30 ... rubber roller, 31, 32 ... metal roller.

Claims (3)

  This is an inking rubber roller. The rubber of the rubber roller consists of two layers, a surface layer and an inner layer. The surface rubber layer is urethane rubber with a hardness of 40-60 in JISA standard hardness, and the hardness of the entire rubber layer Is an inked rubber roller having a hardness of 25 to 35 in the same standard hardness and a tensile strength of the surface rubber is 20 MPa or more.   The inked rubber roller according to claim 1, wherein the rubber layer of the inner layer is acrylonitrile butadiene rubber (NBR), and the hardness thereof is 20 or less in terms of JISA standard hardness.   The inking rubber roller according to claim 1 or 2, wherein the surface rubber layer has a thickness of 3 mm or less.

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