JP2006175665A - Water supply rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water supply rubber roller 10 which can supply water uniformly across the entire width and shows successful productivity and workability in use. <P>SOLUTION: A rubber layer formed on the outer peripheral part of a core material 11 is dual-structured of a lower winding rubber layer 12 and an upper winding rubber layer 14 with higher hardness than the lower winding rubber layer 12. Further, a wrapping part 15 which covers both ends of the lower winding rubber layer 12, extending upto at least, the vicinity of an outer peripheral part of the core material 11, is formed on both ends of the upper winding rubber layer 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water supply rubber roller used for an offset printing machine or the like.

  Conventionally, as shown in FIG. 3, an offset printing machine has a large roller (plate cylinder) 1, a large-diameter roller (blanket cylinder) 3, a plurality of small-diameter ink roller groups 4, a small-diameter water supply rubber roller 7, and the like. It is comprised with the water supply rubber roller group 6 which consists of. The roller 1 is provided with a printing plate 2 such as an aluminum plate whose surface is subjected to a photoresist treatment in order to form a pattern or the like with ink. The large-diameter roller 3 is obtained by winding a rubber plate that receives ink from the printing plate 2 and transfers it to paper. The small diameter ink roller group 4 supplies ink to the printing plate 2. The water supply rubber roller 7 supplies water to the non-image area of the printing plate 2. In addition, 5 is an ink fountain, 8 is a chrome roller, 9 is a water boat.

  Among them, the water supply rubber roller 7 is in contact with the ink on the printing plate 2 and therefore needs to have ink resistance. Generally, a filler (5 to 15% by weight) mainly composed of acrylonitrile butadiene rubber (NBR) is used. It is made of a single-layer synthetic rubber to which a plasticizer (20 to 40% by weight) such as phthalate ester or xylene resin is added. Further, the water supply rubber roller 7 stably supplies an optimal amount of water to the printing plate 2, so that a predetermined nip width (for example, linear pressure 0.5 to 1.0 kg / cm) is applied to the printing plate 2 with a predetermined pressure (for example, linear pressure 0.5 to 1.0 kg / cm). It is necessary to press so that it may become 6-8 mm. Similarly, the water supply rom roller 7 needs to press the chrome roller 8 with a predetermined pressure in order to uniformly obtain a predetermined amount of water from the chrome roller 8. Therefore, conventionally, the water supply rubber roller 7 has a hardness (JIS-A) of 20 ° to 25 °.

  However, the water supply rubber roller group 6 using the water supply rubber roller 7 tends to be supplied with more dampening water at both end portions in the axial direction and the width direction of each roller than the center portion. There is a problem that uniform supply affects the quality of printing. As one of the causes of this problem, as shown in FIG. 4, when the water absorption amount is adjusted by pressing the water supply roller 7 against the chrome roller 8 at a predetermined pressure, the rubber on the outer periphery of the water supply roller 7 is adjusted. It is considered that the deformation occurs so that the end surface of the layer 7a bulges out, and the water in the deformed portion cannot be sufficiently squeezed out. In other words, it is considered that the water rises at both ends of the water supply roller 7 increases.

  The present invention prevents the occurrence of this kind of problem, and there is the following as prior art document information relating to the water supply rubber roller.

Japanese Utility Model Publication No. 64-48237

  In Patent Document 1, in a water supply roller having a hydrophilic rubber layer on the surface, a ring-shaped rubber layer having a hardness higher than that of the hydrophilic rubber layer is fixed to both ends thereof. Thus, unnecessary water rising from both ends of the water supply roller is eliminated, and a uniform amount of dampening water can be supplied over the entire width.

  However, the water supply roller described in Patent Document 1 needs to fix a thin ring-shaped rubber layer to the core material so as to be positioned at both ends of the hydrophilic rubber layer. It is very difficult. Specifically, since the ring-shaped rubber layer is thin, when a force is applied in the diameter direction, the adhesion to the core material is easily peeled off. Therefore, it is necessary to very firmly fix the core material, and there are problems that the processing is difficult and productivity is poor.

  Moreover, since the water supply roller described in Patent Document 1 has a single rubber layer on the outer peripheral portion, the diameter of the water supply roller shrinks as it is used, and a predetermined nip width cannot be obtained with the initially set pushing amount. Print quality cannot be obtained. For this reason, it is necessary to frequently adjust the amount of pressing of the water supply rubber roller into the printing plate, and there is a problem that the production efficiency is low as well as the workability.

  Therefore, an object of the present invention is to provide a water supply rubber roller that can supply water uniformly over the entire width and has good productivity and workability in use.

  In order to solve the above-mentioned problems, a water supply rubber roller according to the present invention includes a two-layer rubber layer formed on an outer peripheral portion of a core material, which includes a lower wound rubber layer and an upper wound rubber layer whose hardness is higher than that of the lower wound rubber layer. It is set as the structure and it is set as the structure which provided the coating | coated part which extended at least to the outer peripheral part vicinity of a core material, and covered the both ends of the said lower winding rubber layer at the both ends of the said upper winding rubber layer.

  In this water supply rubber roller, the lower wound rubber layer has a hardness (JIS-A) of 30 ° or less and a thickness of 60% or more of the total thickness of the two rubber layers, while the upper wound rubber layer has a plasticizer content rate. It is preferable that the hardness (JIS-A) is 40 ° or more by setting the content to 15% by weight or less, and the thickness is 40% or less of the total thickness of the two rubber layers. That is, the plasticizer content of the overwrapped rubber layer that is in direct contact with the ink or the like is reduced (preferably zero), and the amount of extraction of the plasticizer with ink or the like is reduced so that the diameter of the water supply rubber roller is minimized. It is configured.

  Alternatively, the lower rubber layer has a hardness (JIS-A) of 30 ° or less and a thickness of 60% or more of the total thickness of the two rubber layers, while the upper rubber layer is not extracted by using a liquid polymer. Preferably, the hardness (JIS-A) is 40 ° or more and the thickness is 40% or less of the total thickness of the two rubber layers. That is, the upper wound rubber layer that is in direct contact with ink or the like does not contain an extractable plasticizer, and the diameter of the water supply rubber roller is hardly contracted.

  Moreover, it is preferable that the dimension of the said cover part in the width direction shall be 15 mm or more.

  In the water supply rubber roller of the present invention, since the covering portions covering both ends of the lower wound rubber layer are provided at both ends of the upper wound rubber layer, which is harder than the lower wound rubber layer, it is pressed against the chrome roller with a predetermined pressure. When the water is absorbed, it can be prevented that the end surface of the rubber layer bulges. Therefore, dampening water can be absorbed and supplied with a uniform content throughout the width direction of the water supply rubber roller, and good print quality can be obtained. Moreover, since the said coating | coated part can be formed by forming an upper winding rubber layer so that the outer peripheral part of a lower winding rubber layer may be covered, the process is easy and productivity can be improved. Further, since the hard upper wound rubber layer is provided on the surface of the soft lower wound rubber layer, a predetermined nip width can be obtained, and the problem that the diameter shrinks with use can be prevented. As a result, it is not necessary to adjust the amount of pressing into the printing plate, and it is possible to improve production efficiency related to printing as well as workability.

  Specifically, the lower rubber layer has a hardness (JIS-A) of 30 ° or less and 60% or more of the total thickness of both rubber layers, and the upper rubber layer has a hardness (JIS-A) of 40 °. The surface hardness of the water supply rubber roller is harder than the conventional one because the total thickness of the two rubber layers is 40% or less as described above, but the lower rubber layer is soft with a hardness (JIS-A) of 30 ° or less. Since the thickness is increased to 60% or more of the total thickness of both rubber layers so that the overall flexibility is equivalent to that of a conventional water supply rubber roller, a predetermined nip width can be obtained with a predetermined linear pressure.

  Further, since the top wound rubber layer is made of a rubber material having a plasticizer content of 15% by weight or less (preferably zero) or a rubber material to which a liquid polymer is added instead of the plasticizer, It can suppress that a plasticizer etc. extract by dampening water and the diameter of a water supply rubber roller shrinks. As a result, changes in the linear pressure and nip width due to the shrinkage of the diameter are extremely small, and in the conventional configuration composed of a single layer, it was necessary to adjust the nip width every month, but the adjustment period was lengthened. can do.

  In particular, in the water supply rubber roller containing the hardness setting and the material, it is possible to reliably prevent the bulging at both ends by forming the covering portion with a dimension in the width direction of 15 mm or more.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A and 1B show a water supply rubber roller 10 according to an embodiment of the present invention. The water supply rubber roller 10 is formed by forming a rubber layer having a two-layer structure including a lower wound rubber layer 12 and an upper wound rubber layer 14 on an outer peripheral portion of a metal core 11 having shafts protruding from both ends. .

  The lower rubber layer 12 is made of a soft rubber having a relatively high plasticizer content and a hardness (JIS-A) of 30 ° or less. At both ends of the lower wound rubber layer 12, step portions 13 for fixing an upper wound rubber layer 14 to be described later are formed by cutting after the lining.

  The upper rubber layer 14 has a plasticizer content of 15% by weight or less, preferably zero so that the hardness (JIS-A) is 40 ° or more, and is harder than the conventional single-layer water-supplying rubber roller 10. The hard rubber layer 12 is harder than the lower wound rubber layer 12. The upper rubber layer 14 is formed into a cylindrical shape including the upper portion 13 by further lining the surface of the lower rubber layer 12. Thereby, the upper wound rubber layer 14 is located at the outer peripheral portion of the step portion 13 and extends to the vicinity of the outer peripheral portion of the core member 11, and its end surface is positioned flush with the end surface of the step portion 13, A covering portion 15 that covers most of both ends of the lower rubber layer 12 is formed.

  The step 13 of the lower rubber layer 12 has a diameter dimension s1 from the outer peripheral surface to the outer peripheral surface of the core member 11 of 2 mm or less. Here, 2 mm or less includes zero that does not form the stepped portion 13. That is, the stepped portion 13 is not necessarily formed. However, when the step portion 13 is not formed, it is necessary to fix the inner end of the covering portion 15 to the core material 11, and it is very difficult to secure sufficient fixing strength. The part 13 is preferably formed. Further, when the stepped portion 13 is formed with a dimension larger than 2 mm, the dimension in the diameter direction of the covering portion 15 becomes small, and it is impossible to reliably prevent the lower wound rubber layer 12 from bulging to the outside. It is preferable to be 2 mm or less.

  In the present embodiment, the dimension s2 that is the axial direction of the water supply rubber roller 10 and the width direction of the covering portion 15 is set to 15 mm or more. Furthermore, the thickness of the lower wound rubber layer 12 is 60% or more of the total thickness of the two rubber layers 12 and 14, and the thickness of the upper wound rubber layer 14 is 40% or less of the total thickness of the two rubber layers 12 and 14. Yes. However, the thickness of the upper wound rubber layer 14 is preferably 2 mm or more in terms of rubber roller production.

  The width s2 of the covering portion 15 and the hardness and thickness ratio between the lower rubber layer 12 and the upper rubber layer 14 were examined by the inventors of the present application based on experiments, It is what I found. Specifically, first, the optimum values of the hardness and thickness ratio between the lower rubber layer 12 and the upper rubber layer 14 were found by the following first experimental example. Next, an optimum value related to the content of a plasticizer such as a phthalate ester or a xylene resin, which causes the diameter of the water supply rubber roller 10 to shrink, was found by the second experimental example. Thereafter, the optimum width direction dimension s2 of the covering portion 15 is found by the third experimental example.

(First Experiment Example)
First, the present inventors examined the hardness, thickness, and linear pressure-nip width characteristics of a water supply rubber roller 10 having an upper and lower two-layer rubber structure and a water supply rubber roller 10 having a single-layer rubber structure. Examination water supply rubber roller 10 has a core 11 having a diameter of 50 mm,
B. A second first product of the present invention comprising an upper wound rubber layer 14 having a hardness (JIS-A) of 50 ° and a thickness of 3 mm, and an lower wound rubber layer 12 having a hardness (JIS-A) of 20 ° and a thickness of 7 mm. When,
I. The first second invention product b comprising an upper wound rubber layer 14 having a hardness (JIS-A) of 40 ° and a thickness of 4 mm, and an lower wound rubber layer 12 of a hardness (JIS-A) of 30 ° and a thickness of 6 mm. When,
C. A first comparative product c which is a conventional product consisting of a single layer having a hardness (JIS-A) of 30 ° and a thickness of 10 mm;
D. A second comparative product d consisting of a single layer having a hardness (JIS-A) of 50 ° and a thickness of 10 mm;
E. A third comparative product e consisting of an upper wound rubber layer 14 having a hardness (JIS-A) of 50 ° and a thickness of 5 mm and an lower wound rubber layer 12 of a hardness (JIS-A) of 20 ° and a thickness of 5 mm.
When the nip width-linear pressure characteristics of the five types of water supply rubber rollers 10 were measured, the results shown in FIGS. 2A and 2B were obtained.

  That is, the first invention product a exhibits the same characteristics as the first comparison product c currently used, and can be used without any problem. In the second comparative product d, when the same linear pressure as that of the first comparative product c is pressed, the nip width becomes very small, there is almost no adjustment range for supplying the optimum amount of water, and good printing cannot be performed. If the linear pressure is increased in order to secure the nip width, the amount of water supplied decreases, and the required amount of water cannot be supplied. Further, as in the third comparative product e, the rubber layer is made of rubber having the same hardness as that of the first invention product a, and the two rubber layers 12 and 14 are each 5 mm thick. If the thickness of 14 is larger than 40% of the total thickness, the characteristics are close to those of a single layer, and an appropriate nip width cannot be ensured. On the other hand, the second invention product b has a lower nip width than the first invention product a, but it can be used in practice to obtain good printing.

  Therefore, in the product of the present invention, in order to secure a predetermined nip width at a predetermined linear pressure, the thickness of the upper wound rubber layer 14 should be 40% or less of the total thickness of both rubber layers in consideration of other experimental results. There is a need to.

(Second Experimental Example)
Next, in order to confirm the plasticizer content and the resistance to ink (extractability), the plasticizer content to rubber is 0%, 10.0%, 15.0%, 20.0%, 30.0%. The 5 g cubic rubber block was immersed in ink and placed indoors (room temperature 20 ° C.). After 15 days and 30 days, the weight was measured and the weight was measured. The change in weight (percentage) was examined. The result was shown.

  Moreover, although it is not a plasticizer, as an additive having the same effect as the plasticizer, for example, liquid NBR (nitrile rubber type), liquid CR (neoprene rubber type), liquid BR (butadiene type), liquid urethane (polyester type) , Polyether type) and the like. And even if this liquid polymer is added to rubber, it exhibits non-extractability.

  Accordingly, when a rubber added with a liquid polymer (for example, liquid NBR) instead of the plasticizer was immersed in ink under the same conditions as the plasticizer-containing rubber block, the weight change (percentage) was examined. The result shown in Fig. 2 was found to show excellent resistance to ink.

  That is, when the plasticizer content of the top wound rubber layer 14 is 15% by weight or less, the weight change due to the extraction of the plasticizer is small, and the top wound rubber layer 14 to which a liquid polymer is added instead of the plasticizer. However, it was found that there was little change in weight due to extraction of the liquid polymer, and it showed excellent resistance to ink. This indicates that the diameter of the water supply rubber roller 10 does not easily shrink during use. In addition, the same effect was exhibited with respect to the fountain solution.

  However, the rubber whose hardness (JIS-A) is 40 ° or more by adding only 15% by weight or less of the plasticizer or liquid polymer is higher than the hardness (JIS-A) of the conventional water supply rubber roller 10. The water supply rubber roller 10 composed of a single layer of the rubber having a hardness (JIS-A) of 40 ° or more sets a predetermined nip width with a predetermined linear pressure with respect to the printing plate 2 and other rolls (chrome roller 8). I can't do it.

  Therefore, in the present invention, the soft rubber is applied to the lower rubber layer 12 in which the upper rubber layer 14 has a hardness (JIS-A) of 40 ° or more to give sufficient flexibility as a whole. A predetermined nip width is obtained with a predetermined linear pressure for the plate 2 and the like.

  Of course, a slight amount of liquid polymer may be added to the above-described overwrapped rubber layer 14 even when it contains a plasticizer.

(Third experimental example)
Finally, the present inventors have a core material 11 with a diameter of 53 mm, an upper rubber layer 14 with a hardness (JIS-A) of 40 ° and a thickness of 6 mm, a hardness (JIS-A) of 30 ° and a thickness of 4 mm. A two-layered rubber layer having a dimension s1 of the step portion 13 of 2 mm, and a dimension s2 in the width direction of the covering portion 15 is 0 (zero) mm, About the water supply rubber roller 10 which was 10 mm, 15 mm, 20 mm, and 25 mm, the amount of dampening water rising in each part was measured.

As a result, the water supply rubber roller 10 in which the dimension s2 in the width direction of the covering portion 15 is 0 (zero) mm has a larger amount of water rising at both end portions than the center portion and is not uniform. In addition, the water supply rubber roller 10 having a dimension s2 of 10 mm has a smaller difference between the amount of water rising at both end portions and the amount of water rising at the center portion than the 0 mm water supply rubber roller 10 having no covering portion 15 formed. However, it cannot be said that satisfactory print quality is sufficiently secured.
The water supply rubber roller 10 having a dimension s2 of 15 mm has a difference in the amount of water rising between the both end portions and the central portion, but can ensure good print quality. The water supply rubber roller 10 having a dimension s2 of 20 mm has a slight difference in the amount of water rising between the both end portions and the central portion, but can ensure good print quality. The water supply rubber roller 10 having a dimension s2 of 25 mm has almost no difference in the amount of water rising between the both end portions and the central portion, and can sufficiently ensure good print quality.

  Therefore, in the present invention, in order to make the amount of dampening water rising at the water supply rubber roller 10 uniform and ensure good printing quality, the width dimension s2 of the covering portion 15 needs to be 15 mm or more. .

  Thus, in the water supply rubber roller 10 of the present invention, the covering portions 15 that cover both ends of the lower wound rubber layer 12 are provided at both ends of the upper wound rubber layer 14 that is harder than the lower wound rubber layer 12. It is possible to prevent the end surface of the rubber layer from being deformed so as to bulge when the roller 8 is pressed with a predetermined pressure to absorb water. Therefore, dampening water can be absorbed and supplied with a uniform content over the entire width direction of the water supply rubber roller 10, and good print quality can be obtained. Moreover, since the said coating | coated part 15 can be formed by forming the upper winding rubber layer 14 so that the outer peripheral part of the lower winding rubber layer 12 may be covered, the process is easy and productivity can be improved. In particular, in the water supply rubber roller 10 containing the hardness setting and the material, it is possible to reliably prevent bulging at both ends by forming the covering portion 15 with a dimension in the width direction of 15 mm or more.

  Conventionally, as shown in FIG. 4, considering the excessive supply of water at both ends of the water supply rubber roller 10, the chrome on the water supply side passes through the water supply rubber roller 10 from the roller 1 provided with the printing plate 2 for printing. The total length of each roller becomes longer as it goes to the roller 8. However, in the present invention, excessive supply at both end portions can be prevented, and therefore, the device equipped with the water supply rubber roller 10 does not need to be configured as described above. In other words, it is possible to reduce the occupied area necessary for the water supply structure in the equipment to be used, and to reduce the size of the equipment.

  Furthermore, since the surface hardness is harder than that of the conventional water supply rubber roller 10 as described above, ink fountain, paper dust, etc. do not bite into the surface of the water supply rubber roller 10 during use and do not adhere. Therefore, there is no foreign matter adhesion phenomenon on the surface of the water supply rubber roller 10, and there is no bite even if it adheres, so that the cleaning workability is excellent.

  Furthermore, since the hard upper wound rubber layer 14 is provided on the surface of the soft lower wound rubber layer 12, a predetermined nip width can be obtained, and the problem that the diameter shrinks with use can be prevented. As a result, it is not necessary to adjust the amount of pressing into the printing plate, and it is possible to improve production efficiency related to printing as well as workability.

  Specifically, the lower rubber layer 12 has a hardness (JIS-A) of 30 ° or less and 60% or more of the total thickness of the two rubber layers, and the upper rubber layer 14 has a hardness (JIS-A). The surface hardness of the water supply rubber roller 10 is harder than the conventional one because it is 40 ° or more and 40% or less of the total thickness of both rubber layers, but the lower rubber layer 12 has a hardness (JIS-A) of 30 ° or less. Since it is soft and the thickness thereof is increased to 60% or more of the total thickness of both rubber layers so that the overall flexibility is equivalent to that of the conventional water supply rubber roller 10, a predetermined nip width is obtained with a predetermined linear pressure. be able to.

  Further, since the top wound rubber layer 14 is made of a rubber material having a plasticizer content of 15% by weight or less (preferably zero) or a rubber material to which a liquid polymer is added instead of the plasticizer, It is possible to suppress the plasticizer and the like from being extracted by the fountain solution and the diameter of the water supply rubber roller 10 from shrinking. As a result, changes in the linear pressure and nip width due to the shrinkage of the diameter are extremely small, and in the conventional configuration composed of a single layer, it was necessary to adjust the nip width every month, but the adjustment period was lengthened. can do. In particular, when the hardness (JIS-A) of the top wound rubber layer 14 is 50 ° and the plasticizer content is zero, or when a liquid polymer is added instead of the plasticizer, adjustment work is required even after 6 months of use. Moreover, even if the hardness (JIS-A) of the upper wound rubber layer 14 is 50 ° and the plasticizer content is 15% by weight, there is an effect that no adjustment work is required for 4 months of use.

  The water supply rubber roller 10 of the present invention is not limited to the configuration of the above embodiment, and various modifications can be made. In particular, the use application of the water supply rubber roller 10 having the above-described configuration is not limited to an offset printing machine, and can be applied as long as a predetermined amount of water is supplied to a predetermined roller. Obtainable.

(A), (B) is sectional drawing of the water supply rubber roller which concerns on embodiment of this invention. (A) is a chart showing the results of the first experimental example, and (B) is a linear pressure-nip width characteristic diagram of a water supply rubber roller in which (A) is graphed. Schematic diagram of an offset printing machine. It is a fragmentary sectional view which shows the problem of the conventional water supply rubber roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Roller 2 ... Printing plate 8 ... Chrome roller 10 ... Water supply rubber roller 11 ... Core material 12 ... Bottom wound rubber layer 13 ... Step part 14 ... Upper wound rubber layer 15 ... Covering part

Claims (4)

  The rubber layer formed on the outer periphery of the core material has a two-layer structure consisting of a lower wound rubber layer and an upper wound rubber layer having a hardness higher than that of the lower wound rubber layer, and at least cores are provided at both ends of the upper wound rubber layer. A water supply rubber roller, characterized in that a covering portion is provided which extends to the vicinity of the outer peripheral portion of the material and covers both ends of the lower wound rubber layer.   The lower rubber layer has a hardness (JIS-A) of 30 ° or less and a thickness of 60% or more of the total thickness of the two rubber layers, while the upper rubber layer has a plasticizer content of 15% by weight or less. The water supply rubber roller according to claim 1, wherein the hardness (JIS-A) is 40 ° or more and the thickness is 40% or less of the total thickness of the two rubber layers.   The lower rubber layer has a hardness (JIS-A) of 30 ° or less and a thickness of 60% or more of the total thickness of the two rubber layers, while the upper rubber layer is made non-extractable by using a liquid polymer. The water supply rubber roller according to claim 1, wherein the hardness (JIS-A) is 40 ° or more and the thickness thereof is 40% or less of the total thickness of the two rubber layers.   The water supply rubber roller according to any one of claims 1 to 3, wherein a dimension of the covering portion in a width direction is 15 mm or more.

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