JP5261362B2 - Jacket for printing press and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jacket wherein shortening of the service life thereof due to paper edge or UV irradiation can be prevented, and an effect for preventing an ink from sticking can be maintained for a long time. <P>SOLUTION: The jacket 25 includes a flexible metal substrate 26 and a thermally sprayed coating 27 formed on the metal substrate. The thermally sprayed coating is formed by thermally spraying metal powders, or metal powders and ceramic powders on the surface of the metal substrate, and has a concave-convex structure having a porosity of 5-20% and a surface roughness Rz of 20-35 &mu;m. A silicone oil is impregnated in pores 28 of the thermally sprayed coating. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a jacket for a printing press and a method of manufacturing the same, and more particularly to a jacket used for an impression cylinder of an offset sheet-fed double-sided printing press or a UV drying drum of a printing press that dries ink by UV irradiation. The present invention relates to an improvement of a jacket used and a manufacturing method thereof.

  Patent Document 1 has reported in detail the conventional technology related to a jacket (hereinafter also referred to as “impression cylinder jacket”) used for an impression cylinder of a printing press. With the invention of the impression cylinder jacket, an offset sheet-fed double-sided printing press has been practically completed, which has been adopted by printer manufacturers around the world.

  If an impression cylinder jacket with a surface roughness Rmax of 20 to 40 μm is used, such as the impression cylinder jacket of Patent Document 1, the point contact effect is effective at the portion where the paper surface is in contact with the impression cylinder jacket, and the jacket life is increased. A long life of 20 million or more printed sheets can be maintained. However, at the part where the paper edge part contacts the impression cylinder jacket, low surface energy resin (silicone resin, fluororesin, etc.) with low wear resistance is mostly composed of 2 million to 4 million paper loops. Wear and fall off. For this reason, in the case of a machine that prints various sizes of large and small papers, the paper edge scratches on the jacket that occur when printing small sizes of paper cause stickiness when printing large sizes of paper. The rate at which ink is removed in the printing section is extremely increased. For this reason, a printing failure that white lines are easily noticeable in the solid print portion occurs.

  The rate of occurrence of such troubles in printing failures increases as a machine with a larger ratio of printing small-size paper, and as a double-sided printing machine of four-color process ink printing + aqueous varnish coating.

  In general, if a resin with high wear resistance is selected, it is natural that the wear of the resin can be reduced. However, among low surface energy resins, there is no resin that can withstand harsh use conditions, regardless of whether it is a silicone type or a fluorine type resin.

  Also, in offset printing, there is a printing machine that irradiates UV (ultraviolet rays) and instantly dries the ink, but ultraviolet rays have very strong energy and are functional groups such as methyl groups (-CH3) of polymer resins. And the ink releasability of the silicone resin is lost by UV irradiation for a short time (for example, 1 to 2 hours). The reality is that there is no resin that can withstand UV irradiation and maintain the non-adhesive effect over a long period of time.

JP-A-8-12151

  When a paper edge trouble occurs or ink releasability is lost by UV irradiation, there is a problem that the life of the jacket is shortened and the jacket must be frequently replaced.

  Accordingly, an object of the present invention is a jacket used for an impression cylinder of an offset sheet-fed double-sided printing machine, or a jacket used for a UV drying cylinder of a printing machine that dries ink by UV irradiation, and is used for paper edges and UV irradiation. It is an object of the present invention to provide a jacket capable of preventing the shortened life of the jacket and maintaining the ink adhesion preventing effect for a long time.

  Furthermore, it is providing the manufacturing method of a jacket which can manufacture such a jacket suitably.

The present invention is a jacket used for an impression cylinder of an offset sheet-fed double-sided printing machine, or a jacket used for a UV drying cylinder of a printing machine that dries ink by UV irradiation,
A metal substrate;
A thermal spray coating formed by spraying metal powder, or metal powder and ceramic powder on the surface of the metal substrate, having a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm; Have
The surface of the sprayed coating is formed by the coating surface itself after spraying, or formed by polishing the surface of the coating after spraying,
A jacket in which pores of the thermal spray coating are impregnated with silicone oil , and excess silicone oil in the recesses of the thermal spray coating is removed to adhere an oil film to the surface of the thermal spray coating .

Further, the present invention is a method for producing a jacket used for a pressure drum of an offset sheet-fed double-sided printing press or a UV drying drum of a printing press for drying ink by UV irradiation,
Spraying metal powder or metal powder and ceramic powder on the surface of the metal substrate to form a sprayed coating having a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm; ,
Impregnating silicone oil in the pores of the sprayed coating.

  The jacket of the present invention utilizes a smooth surface uneven structure and pores in the thermal spray coating, and has a structure that exhibits an ink adhesion prevention effect by adhering and impregnating silicone oil in the thermal spray coating surface and pores. A method of re-coating silicone oil can be employed.

  For this reason, in a jacket used for an impression cylinder of an offset sheet-fed double-sided printing machine or a jacket used for a UV drying cylinder of a printing machine that dries ink by UV irradiation, the jacket may be replaced due to a paper edge trouble, or by UV irradiation. There is no problem of jacket replacement due to loss of ink releasability. Therefore, according to the present invention, it is possible to provide a jacket that can prevent the life of the jacket from being shortened due to paper edges or UV irradiation and can maintain the ink adhesion preventing effect for a long time.

  Furthermore, according to this invention, the jacket which can maintain an ink adhesion prevention effect over a long time can be manufactured suitably.

It is a figure which shows the structure of the offset sheet-fed double-sided printing machine to which the jacket which concerns on one Embodiment of this invention is applied. It is a figure which shows an example of a structure of the printing unit shown by FIG. It is a figure which shows an example of a structure of the impression cylinder shown by FIG. 1 and FIG. It is a partial expanded sectional view showing typically an example of composition of an impression cylinder jacket. It is a partial expanded sectional view which shows typically the structure of the impression cylinder jacket of a comparative example. It is a partial expanded sectional view which shows typically the part per paper edge after carrying out the actual machine mounting of the impression cylinder jacket of a comparative example, and printing 2-4 million sheets.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation, and are different from the actual ratios.

  Referring to FIG. 1, the offset sheet-fed double-sided printing machine includes a printing unit 10 for performing predetermined printing on a conveyed sheet P (hereinafter simply referred to as “paper”), and a stacked sheet P. A sheet feeding unit 70 for separating the sheets one by one and feeding them to the printing unit 10, a drying unit 60 for drying the ink on the printed paper P conveyed from the printing unit 10 by UV irradiation, and the paper P And a paper discharge unit 80 for stacking.

  The printing unit 10 includes a plurality of printing units 11 to 18. The printing units 11 to 14 are provided on the upper side of the transport path of the paper P and can print the upper surface of the paper P, while the printing units 15 to 18 are provided on the lower side of the transport path of the paper P. The lower surface of the paper P can be printed. The printing units 11 and 15 are black (B) ink, the printing units 12 and 16 are indigo (C) ink, the printing units 13 and 17 are red (M) ink, and the printing units 14 and 18 are yellow (Y). ) It uses ink. As described above, the printing machine shown in FIG. 1 constitutes an offset sheet-fed double-sided 4 / 4-color printing machine that employs a method of alternately printing the front and back sides without reversing the paper.

  In order to simultaneously dry both sides of the paper P, the drying unit 60 is disposed so as to face the upper UV drying cylinder 61 and the upper surface of the UV drying cylinder 61 and irradiates UV toward the paper P on the UV drying cylinder 61. It has a UV unit 63, a lower UV drying cylinder 62, and a lower UV unit 64 that is arranged facing the UV drying cylinder 62 and irradiates UV toward the paper P on the UV drying cylinder 62. .

  The printing unit 11 will be described with reference to FIG. The other printing units 12 to 18 have the same configuration as the printing unit 11 and will not be described.

  As shown in FIG. 2, the printing unit 11 includes a plate cylinder 21 around which a printing plate (not shown) is wound, and a blanket cylinder for transferring the ink of the pattern on the printing plate wound around the plate cylinder 21 to paper. 22, an impression cylinder 23 for holding paper with nails (not shown) and pressing it against the blanket cylinder 22, and an ink supply unit 60 capable of supplying ink to the plate cylinder 21. A rubber layer for generating an appropriate printing pressure is formed on the surface of the blanket cylinder 22. As shown in the figure, the blanket cylinder 22 is disposed to face the impression cylinder 23, and the plate cylinder 21 is disposed to face the blanket cylinder 22. The paper is conveyed one by one from the right in the figure, is held by the nail of the impression cylinder 23, and is printed by being brought into pressure contact with the blanket cylinder 22. The ink supply unit 60 includes a plurality of ink supply rollers 61 that can contact and be separated from the plate cylinder 21.

  With reference to FIG. 3, the impression cylinder 23 includes an impression cylinder body 24 and a jacket 25 wound on the impression cylinder body 24. Although not shown, the UV drying cylinders 61 and 62 are similarly composed of a drying cylinder main body and a jacket wound on the drying cylinder main body.

  Referring to FIG. 4, the jacket 25 includes a flexible metal substrate 26 and a thermal spray coating 27 formed on the metal substrate 26. The thermal spray coating 27 is formed by spraying metal powder and ceramic powder on the surface of the metal substrate 26, and has a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm. Yes. The pores 28 of the thermal spray coating 27 are impregnated with silicone oil. In the drawing, reference numeral 29 a indicates an oil film of silicone oil, and reference numeral 29 b indicates silicone oil impregnated in the pores 28.

  As the material of the metal substrate 26, for example, stainless steel, aluminum alloy or the like is selected. The thickness of the metal substrate 26 is, for example, 0.2 to 0.4 mm. If necessary, the surface of the metal substrate 26 can be degreased, blasted, or degreased and blasted.

  The purpose of making the surface of the thermal spray coating 27 into a concavo-convex structure is to bring the ink from the paper into contact with the paper at the convex portion when it comes into contact with the paper as the printing material and the silicone oil present on the surface of the convex portion. This is to make it difficult to occur. In terms of roughness, the height of the uneven peaks is preferably Rz 20 to 35 μm, more preferably Rz 23 to 32 μm, and even more preferably Rz 25 to 30 μm. If Rz is less than 20 μm, the ink adhesion effect due to point contact with the paper is lowered, and the silicone oil present on the surface of the concave portion is also transferred to the paper and easily causes ink trapping failure. If Rz is more than 35 μm, white spots in the printed portion are increased, and printing faults such as scratches are easily discerned visually, which is not preferable. “Rz” is a ten-point average roughness defined by the standard of JIS standard B0601-1982.

  The thermal spray coating 27 has porous, preferably fine pores 28 of 0.1 μm to several tens of μm with a porosity of 5 to 20%. As for the porosity, the portion of the pore 28 is traced from an image obtained by observing a cross section of the sprayed film with an SEM or the like, the area of the pore 28 is measured using image processing software, and the area of the pore 28 and the sprayed film is measured. It can be measured by dividing by. The size of the pores 28 can also be measured by the same cross-sectional image analysis method.

  The reason why a porosity of 5 to 20% is preferable is as follows. If the porosity is less than 5%, the oil retaining amount of the silicone oil impregnated in the pores is reduced, and the effect of preventing the ink stain from the jacket is shortened. A porosity of more than 20% is not preferable because the adhesion and wear resistance between the thermal spray coating and the metal substrate are reduced.

  Examples of the thermal spraying method of the thermal spray material include plasma thermal spraying, arc thermal spraying, gas flame thermal spraying, and the like, preferably plasma thermal spraying.

  For example, a metal such as Al, Ni, Cr, or a metal alloy is selected as the material of the metal powder that is the thermal spray material. From the viewpoint of cost and the like, Ni—Al is preferable, and Ni—Cr is most preferably used.

The material of the ceramic powder that is the thermal spray material is Al ₂ O ₃ , TiO ₂ , Al ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ , ZrO ₂ , WC, WC—Co, Cr ₃ C ₂ , TiC, or the like. A mixture is used. In general, white alumina (W—Al ₂ O ₃ ), gray alumina (G—Al ₂ O ₃ ), (Al ₂ O ₃ —TiO ₂ ) and the like are desirable from the viewpoint of cost and the like.

  The particle size range of the metal powder is preferably 5 to 44 μm, and the particle size range of the ceramic powder is preferably 5 to 44 μm.

  It is difficult to make the particle size range of the thermal spray material less than 5 μm or more than 44 μm completely in the material sieving process, and making it so severe is uneconomical from the viewpoint of cost increase. . However, according to the standard of the particle size range defined in JIS standard R6001, the variation in the particle size range is too large. For this reason, it is preferable to manage by the value measured by the electrical resistance test method (JIS standard R6002) or the laser diffraction method, and that the particle size range exceeds or is less than 5%.

  The reason why it is preferable that the metal powder and the ceramic powder have a particle size of more than 44 μm is 5% or less is as follows.

  In general, the thermal spray material that is commercially available has a specific particle size configuration for each material maker, but even if it has a particle size width of 10 to 44 μm, it contains a lot of particles that greatly exceed the upper limit of the control width of 44 μm. . As a general thermal spray product, even if these materials are sprayed, there is almost no problem.

  On the other hand, the purpose of thermal spraying on the impression cylinder jacket is to form a concavo-convex structure in which the peaks of the convex parts are aligned, and to receive the point contact effect by receiving the paper surface when printing between the rubber cylinder and the impression cylinder at the convex parts. It is to prevent ink stains. Therefore, if there is a protrusion that is abnormally high or large in the height of the peak of the convex portion, this will take ink on the printing surface, resulting in scratches on the printed matter and white spots.

For this reason, if the sprayed material contains more than 5% of coarse particles exceeding 44 μm, it is particularly large in size as it is bonded as it is or with other coarse particles. And adheres to the metal substrate 26. This is not something that can be confirmed by visual inspection, and it is possible to measure only a few points on a wide jacket (1 m ² ) surface with a length of 12.5 mm even in the inspection by roughness measurement. There is a problem. The roughness measuring method described here is based on JIS standard B0601-1982, and the measurement length includes both 4 mm and 12.5 mm. In order to increase the measurement accuracy, even if the measurement is performed at 12.5 mm, there is a possibility that the abnormal protrusion may be missed as described above.

  Therefore, by using an impression cylinder jacket in which the material particle size control width is strictly limited to 5 to 44 μm (over 44 μm is 5% or less), it becomes possible to print a printed matter having no scratches and small white spots. .

  The thickness of the thermal spray coating 27 is determined from the thickness specification of the impression cylinder jacket and the thickness of the metal substrate 26 to be used. The thickness of the thermal spray coating 27 is preferably 20 to 150 μm, more preferably 30 to 100 μm, and still more preferably 30 to 50 μm. If the thickness of the thermal spray coating 27 is less than 20 μm, the silicone oil impregnation effect is small, which is not preferable. If the thickness of the thermal spray coating 27 exceeds 150 μm, the probability that the coarse particles of the thermal spray material overlap with each other also increases, which becomes an abnormal protrusion, which increases the probability of causing scratches on the printed matter and white spots, which is not preferable. It is also a factor of cost increase.

  The illustrated sprayed coating 27 is formed by spraying a mixture of metal powder and ceramic powder in advance, but the sprayed coating 27 of the present invention is not limited to this case. For example, by thermally spraying metal powder and secondarily spraying ceramic powder on this metal layer, the thermal spray coating has a concavo-convex structure with a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm. May be formed. Alternatively, a thermal spray coating having a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm may be formed by spraying only metal powder.

  A well-known thing can be used as a silicone oil, for example, dimethyl silicone oil (For example, the Shin-Etsu Chemical Co., Ltd. make, brand name "KF-96" etc.) can be used.

  In manufacturing the jacket, the step of impregnating the silicone oil in the pores 28 of the sprayed coating 27 includes the step of applying the silicone oil diluted with the volatile solvent to the sprayed coating 27 and the thermal spraying of the silicone oil diluted with the volatile solvent. It is preferable to have a step of evaporating the volatile solvent after impregnating the pores 28 of the coating 27.

  At the time of application, it becomes easy to impregnate the low-viscosity silicone oil into the pores 28 by diluting with a volatile solvent, and after application, the high-viscosity silicone oil is filled into the pores 28 by evaporating the volatile solvent. It is because it is easy to make it into a state.

  As the volatile solvent, for example, toluene, MCH (methylcyclohexane), C9 isononane, glycol ethers and the like can be used. Although the viscosity of the silicone oil at the time of application | coating can be suitably adjusted according to the magnitude | size of the pore 28, etc., about 100 cSt can be illustrated, for example. Moreover, although the viscosity of the silicone oil after evaporating a volatile solvent can be adjusted suitably similarly, for example, about 6,000-1 million cSt can be illustrated. When it is necessary to avoid regulations such as the PRTR method (Chemical Emission Control Management Promotion Act), it is also possible to use a solventless, low-viscosity (100 cSt) silicone oil. In that case, the ink non-adhesive sustaining effect is slightly reduced.

  After applying the silicone oil, it is preferable to have a step of removing excess silicone oil on the surface of the sprayed coating 27 with a liquid absorbing member before evaporating the volatile solvent.

  A high-viscosity silicone oil diluted with a volatile solvent is impregnated and applied into the pores 28 of the spray coating 27 having an uneven surface structure, and excess liquid silicone oil adhering to the surface of the spray coating 27 is applied by the liquid absorbing member. After wiping off, the printing operation is started. This is because the silicone oil on the jacket is not transferred to the paper, and there is no adverse effect that causes an ink trapping failure during subsequent printing. This is because the uneven surface of the thermal spray coating 27 is formed on the jacket surface, and the contact with the paper surface is only a minute convex portion of the thermal spray coating 27, so that the oil film of silicone oil adhering to the concave portion of the thermal spray coating 27. This is because the paper surface hardly touches 29a. Of course, the silicone oil on the jacket is transferred to the paper several times after starting printing, but at the beginning of the work, dozens of pieces of paper are always passed through registration and color matching. There is no problem in practical use.

  The liquid absorbent member is preferably formed of a material that has good liquid (silicone oil) absorbability and is less likely to cause fluff residue, such as ultrafine fiber nonwoven fabric, sponge, sponge cloth (for example, manufactured by Aion Co., Ltd., The trade name “Plus Seine”) can be used. When such a liquid absorbing member is used, the surplus silicone oil in the recesses of the sprayed coating 27 is wiped off by the liquid absorbing member cloth just by lightly wiping the jacket surface, and the oil film 29a of the thin silicone oil and the pores 28 in the pores 28 are removed. Only the silicone oil 29b can be left. Further, if this liquid absorbing member is used, the wiping operation is very simple and efficient, and no fluff residue is generated.

  It is preferable to further include a step of polishing the surface of the coating after thermal spraying before performing the step of impregnating the silicone oil.

  In the jacket 25 of this case, in which silicone oil is applied to the thermal spray coating 27 and impregnated in the pores 28, an operation of wiping off the excess liquid of the applied silicone oil is necessary. Is very steep, there is a possibility that the fluff (fiber) of the cloth will be caught by the protrusions and cause a printing trouble due to the remaining fluff. This is because the surface of the thermal spray coating 27 needs to have a smooth hand to prevent this. In the polishing, the surface of the coating surface after thermal spraying is lightly polished using sandpaper, and the thermal spray coating 27 has a surface roughness difference ΔRz between the surface roughness Rz after thermal spraying and before polishing and the surface roughness Rz after polishing. It is preferable to form in the shape which becomes 2-5 micrometers. Polishing with a surface roughness difference ΔRz of less than 2 μm is not preferable because sharp fine irregularities on the coating surface after spraying cannot be sufficiently smoothed and the effect of reducing the fluff residue cannot be obtained sufficiently. Further, in the polishing in which the surface roughness difference ΔRz exceeds 5 μm, the surface of the coating is polished more than necessary, which is not preferable from an economical viewpoint and an increase in the amount of work. As the sandpaper, for example, about # 600 to # 1500 can be used. Note that the polishing method is not limited to sandpaper.

  As described above, the surface roughness Rz of the thermal spray coating 27 as a product needs to be Rz 20 to 35 μm. Therefore, when the coating surface after thermal spraying is polished, when the polishing allowance is 2 μm, the surface roughness of the coating surface after thermal spraying is required to be Rz22 to 37 μm, and the polishing allowance is 5 μm. In some cases, the surface roughness of the coating surface after thermal spraying needs to be Rz25 to 40 μm. However, the present invention is not limited to polishing the surface of the coating after thermal spraying. If the surface roughness of the sprayed coating as a product is Rz20-35μm and the tip of the projected portion of the sprayed coating is smooth enough to prevent printing failure due to the remaining fuzz, the surface of the sprayed coating is polished. The work to do is not essential.

  A test for checking the fluff residue was performed as follows. First, one half of one jacket was not polished as it was after thermal spraying, and the other half of the coating surface was polished. The surface roughness Rz of the unpolished region was 30 to 35 μm, and the surface roughness Rz of the polished region was 28 to 33 μm. The prepared test jacket was attached to an impression cylinder, and after impregnation with silicone oil, excess oil was wiped off with a dry synthetic fiber waste. After that, the printing test was performed so that the paper on which the entire surface was black ink solid-printed was in contact with the test jacket. In the non-polished region, white spots of fluff marks were observed up to about the 20th sheet of paper thread, but in the polished area, no white spots of fluff marks were observed at the fifth sheet thread. From this test, the fluff residue can be greatly reduced by forming the sprayed coating in a shape in which the surface roughness difference ΔRz between the surface roughness Rz after spraying and before polishing and the surface roughness Rz after polishing is 2 μm. Was confirmed.

  In the jacket of the present embodiment, the silicone oil impregnated and applied to the thermal spray coating 27 does not solidify, so that the ink adhesion preventing effect of the silicone oil is lost in a very short time as compared with the silicone resin described in Patent Document 1. For example, when the number of paper passes is 10,000 to 100,000, the ink adhesion preventing effect is lost. If ink adhesion increases, the ink or paper dust adhering to the jacket is washed with a highly volatile solvent such as gasoline, and silicone oil is reapplied. When the silicone oil is reapplied, the step of applying the silicone oil diluted with the volatile solvent to the sprayed coating 27 and the silicone oil diluted with the volatile solvent are applied in the same manner as the step of impregnating the silicone oil in the production stage. It is preferable to include a step of evaporating the volatile solvent after impregnating the pores 28 of the thermal spray coating 27. At the time of re-application, it becomes easy to impregnate the low-viscosity silicone oil into the pores 28 by diluting with a volatile solvent. It is because it is easy to make it the filled state.

  The cleaning operation may be performed with the remaining silicone oil. The jacket can be used over a long period of time by re-applying silicone oil until the surface roughness of the thermal spray coating 27 is reduced to a surface roughness below the limit (20 μm or less) due to wear.

  In the impression cylinder jacket described in Patent Document 1, the silicone resin is locally worn by the paper edge in a short period of time, and due to a paper edge problem, the jacket must be replaced with 2 million to 4 million paper threaders. There was also a short life. On the other hand, since the jacket 25 of the present embodiment employs the silicone oil impregnation method, the phenomenon that the silicone oil falls off due to the paper edge and causes a paper edge trouble does not occur.

  In addition, the low surface energy resin (silicone resin) has a large non-adhesive function of the functional group (-CH3). However, when UV irradiation is performed, the functional group (-CH3) is cut off by very strong ultraviolet energy. There is a problem that the non-adhesiveness is impaired and the ink stain of the jacket is increased. On the other hand, the silicone oil used in the jacket 25 of this embodiment is a silicone oil that does not solidify from the beginning, and is a silicone oil that can be reapplied repeatedly when the ink adhesion prevention effect is reduced. For this reason, characteristic deterioration due to UV irradiation does not occur. Therefore, the jacket according to the present invention is an offset sheet-fed double-sided printing machine equipped with an ink drying device using a UV irradiation system, and is used as an impression cylinder jacket in which UV leaking from the UV irradiation system is irradiated due to structural limitations. Can also be used. Furthermore, in addition to the impression cylinder jacket, it can also be suitably used for a jacket used for the UV drying cylinders 61 and 62 of a printing press that dries ink by UV irradiation. In this case, since the printing pressure is not applied unlike the impression cylinder, the silicone oil on the jacket is gradually removed, and the application frequency of the silicone oil may be about once per week.

  The jacket 25 of the present embodiment is based on the premise that the silicone oil is repeatedly applied again. However, unlike the conventional technique in which the silicone oil is applied to a smooth surface such as a chrome-plated impression cylinder, the porosity is 5 to 20. %, And the pores 28 of the thermal spray coating 27 having an uneven structure with a surface roughness Rz of 20 to 35 μm are impregnated with silicone oil. By adopting such a system, the silicone oil 29b in the pores 28 of the thermal spray coating 27 is gradually softened by the heat at the time of printing and oozes out on the surface to continuously form the oil film 29a of the silicone oil over a long period of time. The effect of preventing ink adhesion is maintained.

  Further, by utilizing the point contact effect between the convex portion of the thermal spray coating 27 and the paper, the silicone oil is prevented from being transferred to the paper as much as possible to prevent the adverse effect of the silicone oil being transferred to the paper. The effect of reducing the number of coatings can be provided.

  In addition, high-viscosity silicone oil is difficult to impregnate into the fine pores 28 of the ceramic as it is, but when applied, it is smoothly diluted into the fine pores 28 by diluting with a highly volatile solvent and keeping the viscosity low. Impregnated with silicone oil. After the application, when the liquid silicone oil adhering to the surface is wiped off by the liquid absorbing member, only the silicone oil solvent remaining in the pores 28 is evaporated and the pores 28 are filled with the high viscosity silicone oil. Of course, only high-viscosity silicone oils are not effective as silicone oils, but there are also low-viscosity silicone oils that do not require solvent dilution. This is more effective in terms of coating workability and solvent handling regulations such as the PRTR method. ,preferable. On the other hand, from the viewpoint of the silicone residue in the pores 28 and the transferability to paper, an oil having a low viscosity obtained by diluting a high viscosity silicone with a volatile solvent is applied, and the excess liquid is wiped off by a liquid absorbing member. It is preferable that high-viscosity silicone remains in the pores 28 after volatilization of the solvent.

  When printing is started, the silicone oil on the surface of the sprayed coating 27 gradually moves to the paper side, and the non-adhesiveness gradually decreases. However, since the impression cylinder is heated by machine operating heat or UV drying heat, the high-viscosity silicone oil 29b in the pores 28 is softened and oozes out to the surface. Due to these actions, unlike the conventional technique in which silicone oil or silicone wax is applied to the surface of a smooth chrome-plated impression cylinder to prevent ink adhesion, the impression cylinder to which the jacket of the embodiment is applied is made of silicone oil. Non-adhesive lasting effect can be significantly prolonged.

  Needless to say, the cleaning of the impression cylinder jacket or the re-coating operation of the silicone oil may be performed by any of manual wiping, hand coating, or machine automation.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, the scope of the present invention is not limited only to these Examples.

(Comparative example)
A SUS plate having a thickness of 0.25 mm, the particle size range of _{Ni-Cr; 10~38μm, G-} Al 2 O 3; and spraying the thermal spray material of 10～44Myuemu, spray thickness 50 [mu] m, porosity of 18%, spraying A sprayed coating having a concavo-convex structure having a surface roughness Rz of 35 to 40 μm was formed. A silicone resin, which is a low surface energy resin, was coated so that the convex portion of the thermal spray coating was thin, the concave portion was thick, and the surface roughness after coating was Rz 30 to 35 μm. The silicone resin was dried and solidified at 130 ° C. for 30 minutes to produce an impression cylinder jacket described in Patent Document 1. FIG. 5 shows an enlarged cross-sectional structure of the impression cylinder jacket 100 of the comparative example. In the figure, reference numeral 101 denotes a metal substrate, 102 denotes a sprayed coating, 103a denotes a cured silicone resin on the sprayed coating 102, and 103b denotes a cured silicone resin in the pores of the sprayed coating 102.

  Here, the silicone resin was selected from among the low surface energy resins because the ink releasability was the best (gum tape peeling force: 0 to 10 g), and then the one with excellent wear resistance was tested in the actual machine operation test. After confirmation, it was adopted as the resin that shows the best performance.

  Even if it is limited to the low surface energy resin (silicone resin) of the type that is dry-cured, there are countless resins. Conventionally disclosed low surface energy resins include those having a very low surface tension with water, but the lower the surface tension, the lower the ink adhesion to the impression cylinder jacket. Not exclusively. As a result of various experiments by the inventor, the adhesive strength of the impression cylinder jacket is more determined by the peeling force of the gum tape devised by the inventor than by the surface energy index (surface tension; calculated from contact angle measurement with water). It is excellent as an evaluation method.

  The gum tape peeling force as a non-adhesive index described here is a quantitative evaluation method originally conceived by the present inventors, and a 25 mm wide Nitto Denko cloth adhesive tape (product number: N0.750) is dried. It is affixed to the surface of a cured non-adhesive resin, measures the force to peel off the tape in a perpendicular direction, and measures the non-adhesiveness by the magnitude of the force.

Example 1
A SUS plate having a thickness of 0.25 mm was sprayed with a thermal spray material having a particle size range of Ni—Cr; 10 to 25 μm, G—Al ₂ O ₃ ; A thermal spray coating having a concavo-convex structure having a surface roughness Rz of 30 to 35 μm was formed. Furthermore, the coating surface after thermal spraying was lightly polished with sandpaper (# 1000) to obtain a thermal spray coating having a surface roughness of Rz 28 to 33 μm and a smooth touch (surface roughness difference ΔRz 2 μm). Further, a high-viscosity silicone oil (KF-96H-1 million cs) manufactured by Shin-Etsu Chemical Co., Ltd .: low-viscosity silicone oil diluted at a ratio of toluene = 1: 4 was coated and impregnated on the surface of the sprayed coating. Excess oil on the surface of the sprayed coating was wiped off with an ultrafine fiber cloth (trade name “PLUS SEINE” manufactured by Aion Co., Ltd.). The diluent evaporated in a short time. As a result, a high-viscosity silicone oil remained in the pores of the sprayed coating, and a jacket used for an impression cylinder of an offset sheet-fed double-sided printing machine was manufactured. The enlarged cross-sectional structure of the impression cylinder jacket of Example 1 is as shown in FIG.

(Example 2)
An impression cylinder jacket was produced in the same manner as in Example 1 except that the low-viscosity silicone oil (KF-96-100cs) manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone oil.

(Print test with actual machine)
A comparative test by a long-term printing operation was performed with the impression cylinder jackets of Comparative Example, Example 1 and Example 2 mounted on an offset sheet-fed double-sided printing press.
(1) Frequency of white spots / jacket cleaning The percentage of white spots in the solid four-color overprinted part of the process ink four-color (B, C, M, Y) printing on the coated paper with the jacket of the comparative example is as follows. 3%, 15 million paper passers, 7%. Moreover, when the jacket was new, up to 50,000 prints, the jacket was clean and good without being washed. As the number of papers passed increased, the silicone resin wear of the ceramic convex portion increased, ink was removed from the jacket, the white spot rate increased, and the jacket cleaning frequency increased. For 15 million sheets of paper, it was necessary to clean the jacket about once per 10,000 sheets printed.

  On the other hand, in the jacket of Example 1, when the same printing as in the comparative example was performed, there was no solidified silicone resin in the thermal spray coating recess, but an oil film of silicone oil was formed on the uneven surface and pores of the thermal spray coating. Is formed. For this reason, compared with a jacket having only a thermal spray coating, the ink adhesion to the jacket is very small, and the white spot ratio of the printed portion is also reduced to a surface roughness Rz of 20 to 35 μm. It was 4% which did not change greatly.

  However, ink adhesion to the impression cylinder jacket is larger than that in the comparative example. Even when the impression cylinder jacket is new, it is necessary to perform cleaning once per 10,000 prints (automatic cleaning in accordance with the cleaning of the blanket cylinder), and once / shift requires re-application of silicone oil. Here, 1 shift is 8 to 12 hours.

  As for the change in the white spot ratio due to long-term use, if the re-application of the shift silicone oil is continued once, the ink adhesion preventing effect of the jacket is reduced until the surface roughness of the sprayed coating becomes Rz 20 μm or less (total The number of sheets passed through; 50 million) was maintained in the 4-6% range for a long time.

(2) Paper edge scratch trouble Since the jacket of the comparative example is a composite coating of a thermal spray coating and a silicone resin and has a surface roughness of Rz 30 to 35 μm, the abrasion resistance is low in a place where the paper is in a planar shape. (Pencil hardness; 4B) Silicone resin is hardly worn except for the convex portion of the sprayed coating. However, since a strong printing pressure is locally applied between the blanket cylinder and the impression cylinder at the jacket portion in contact with the paper edge portion, the silicone resin in the concave portion of the spray coating is short-term (paper thread; 2 million to 4 million). ) And wear off. This state is schematically shown in FIG. In the figure, reference symbol a1 indicates a zone that always contacts the paper during printing, a2 indicates a zone where the paper edge hits during printing, and a3 indicates a zone where the paper does not contact during printing.

  Then, only the paper edge scratches at the time of printing on a small paper size selectively pick up the ink on the solid printing part of the paper at the time of printing on a large paper size, so that a blank paper edge line appears in the printing part and the printing is defective. Become.

  On the other hand, since the impression cylinder jacket of Example 1 applies silicone oil at a frequency of once / shift, a silicone oil oil film is formed on the paper edge portion in the same manner, and ink releasability is good. Therefore, the phenomenon that ink is taken out only at the portion in contact with the paper edge portion does not occur. Therefore, not only general process ink four-color printing, but also printing that is likely to cause paper edge troubles, such as process ink four-color printing and aqueous varnish printing, hardly causes paper edge troubles.

(3) Printing with UV ink A UV irradiation test was performed as follows. Seven impression cylinder jacket samples (50 × 100 mm) coated with oil were applied on a conveyor, and UV irradiation was performed while rotating at a constant speed. Each time the set device operating time was reached, the impression cylinder jacket sample was removed, and changes in mold release properties (gum tape peeling force, magic ink (registered trademark) wiping property) were measured.

  The specifications of the UV irradiation apparatus are as follows. Lamp: metal halide lamp, light emission length: 125 mm, output: 1.5 kw, conveyor speed 1.5 m / min, irradiation distance: 100 mm, irradiation operation time: 1 Hr, 3 Hr, 5 Hr, 7 Hr, 9 Hr.

  The gum tape peeling force is as described above.

  The magic ink (registered trademark) wiping property is an evaluation method uniquely devised by the inventor of the present patent, and 7 mm × on the sample using magic ink (registered trademark, product model number ML-T2) manufactured by Teranishi Chemical Industry. A mark is applied to a range of 15 mm, a 25 mm wide Nitto Denko cloth adhesive tape (product number: N0.750) is applied, and the tape is peeled off in a perpendicular direction. Then, the number of times of sticking / peeling of the adhesive tape required for wiping off the mark is counted.

  The change in the releasability of the jacket of the comparative example is shown in Table 2 below, and the change in the releasability of the jacket of Example 1 is shown in Table 1 below.

The amount of light in Table 1 is obtained from the amount of light (mJ / cm ² ) = illuminance (mW / cm ² ) × UV irradiation time (s). The illuminance under the irradiation conditions is about 1400 mW / cm ² (manufacturer reference value).

  As shown in Table 2, it was found that the jacket of the comparative example was 7 Hr after UV irradiation, the gum tape peeling force was 160 g, and the releasability was reduced. Further, after 9 hours of UV irradiation, it was found that the peel strength of the gum tape was 200 g or more, the magic ink (registered trademark) wiping property was twice, and the ink releasability was almost lost. Therefore, the feature that the ink is not adhered to the jacket by coating with the low surface energy resin is lost.

  On the other hand, the jacket of Example 1 had a gum tape peeling force of 10 g or less even after 7 hours after UV irradiation and 9 hours after UV irradiation, and the releasability was hardly deteriorated. When impregnated with silicone oil as in Example 1, it is a type of silicone oil that does not solidify originally, and is a silicone oil that can be re-applied repeatedly when the ink adhesion prevention effect is reduced. Does not occur. Therefore, it was confirmed that the impression cylinder jacket of this patent can also be used in an offset sheet-fed double-sided printing machine equipped with an ink drying device using a UV irradiation system.

  Needless to say, it can be used not only for the impression cylinder but also for the transfer cylinder for UV drying (UV drying cylinder). In the case of a UV drying transfer cylinder, the silicone oil on the jacket is difficult to remove because no printing pressure is applied. Therefore, the frequency of re-application of silicone oil may be about once / week.

(4) Jacket life The average jacket life of the comparative example is about 20 million sheets, but in a machine with a high ratio of small-size paper printing or a machine that performs inline aqueous varnish coating, 2 million to 400 sheets. Short life of 10,000 sheets.

  On the other hand, since the jacket of Example 1 is a system in which silicone oil is periodically reapplied, paper edge trouble is unlikely to occur. Therefore, there is no problem of short life due to paper edge trouble.

  Since the jacket of Example 1 is not a solidified type silicone resin, the work of applying the silicone oil once / shift is certainly increased as compared with the comparative example. However, there is no short life due to paper edge troubles, and there is no increase in the white spot rate due to long-term use. Therefore, the life of Example 1 can be expected to be 50 million sheets or more.

  Further, the jacket of the comparative example cannot be used at all in a cylinder that receives direct UV irradiation in a UV irradiation machine. However, the jacket of Example 1 was able to maintain a practically high ink adhesion preventing effect for a long period of time by periodically performing the silicone oil application operation.

  The difference between Example 1 and Example 2 is the difference in the viscosity of silicone oil, and considering the workability of silicone oil application, the workability of Example 2 is better because the solvent does not evaporate.

  However, Example 1 is a high-viscosity silicone oil, which has better persistence in the ceramic pores after solvent volatilization, so the silicone oil recoating cycle can be lengthened.

  Regarding the viscosity of the silicone oil, those in a very wide range are commercially available, and can be appropriately selected from these. That is, the solvent can be easily applied by impregnation, and the solvent selection and dilution ratio can be adjusted in consideration of the volatility of the solvent.

25 jacket,
26 metal substrate,
27 Thermal spray coating,
28 pores,
29a Oil film of silicone oil,
29b silicone oil impregnated in the pores;
61, 62 UV drying cylinder,
63, 64 UV units,
100 impression cylinder jacket of comparative example,
101 metal substrate,
102 spray coating,
103a cured silicone resin,
103b A cured silicone resin in the pores.

Claims (6)

A jacket used for an impression cylinder of an offset sheet-fed duplex printing machine, or a jacket used for a UV drying cylinder of a printing machine for drying ink by UV irradiation,
A metal substrate;
A thermal spray coating formed by spraying metal powder, or metal powder and ceramic powder on the surface of the metal substrate, having a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm; Have
The surface of the sprayed coating is formed by the coating surface itself after spraying, or formed by polishing the surface of the coating after spraying,
A jacket in which silicone oil is impregnated in pores of the thermal spray coating , and excess silicone oil in the recesses of the thermal spray coating is removed to adhere an oil film to the surface of the thermal spray coating . The surface of the sprayed coating is formed by polishing the surface of the coating after thermal spraying, and the surface roughness difference ΔRz between the surface roughness Rz after thermal spraying and before polishing becomes 2 to 5 μm. The jacket according to claim 1, which is formed in a shape. A jacket used for an impression cylinder of an offset sheet-fed double-sided printing machine, or a jacket used for a UV drying cylinder of a printing machine for drying ink by UV irradiation,
Spraying metal powder or metal powder and ceramic powder on the surface of the metal substrate to form a sprayed coating having a concavo-convex structure having a porosity of 5 to 20% and a surface roughness Rz of 20 to 35 μm; ,
Impregnating silicone oil in the pores of the sprayed coating. The stage of impregnating with silicone oil
Applying silicone oil diluted with a volatile solvent to the sprayed coating;
The method for manufacturing a jacket according to claim 3, further comprising the step of evaporating the volatile solvent after impregnating the pores of the sprayed coating with silicone oil diluted with a volatile solvent.   The manufacturing method of the jacket of Claim 4 which further has the step of removing the excess silicone oil in the surface of the said thermal spray coating by a liquid absorption member after apply | coating a silicone oil and before evaporating a volatile solvent. Before performing the step of impregnating the silicone oil, further comprising polishing the surface of the coating after spraying;
The manufacturing method of the jacket of Claim 5 which forms the said thermal spray coating in the shape from which surface roughness difference (DELTA) Rz of the surface roughness Rz after the thermal spraying before the grinding | polishing and the surface roughness Rz after the grinding | polishing becomes 2-5 micrometers. .