JP2005047241A - Jacket for sheet offset press transfer cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jacket for a sheet offset press transfer cylinder (a middle cylinder) which is little in an attached stain of ink, easy to be washed, high in durability, difficult to generate a scratch flaw to printed matter and difficult to generate electrification. <P>SOLUTION: For the jacket, porous electric conductive metal is sprayed onto a metal made plate, heights of crests of a projected part are made uniform by lightly polishing protrusions of a sprayed film, and further a releasing agent (a low surface energy resin) is filmed on the surface so that a projected part of the sprayed film is thin, the depressed part is thick and an irregularity of the sprayed film is remained to provide a composite covered film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement in preventing ink stains on a jacket for a sheet-fed offset printing machine transfer cylinder (intermediate cylinder).

  In a sheet-fed offset multicolor printing machine, it is common to have a transfer cylinder (also referred to as an intermediate cylinder) for transferring paper between the black, indigo, red and yellow printing units and other printing units. is there.

  As an example, in the sheet-fed offset multicolor duplex printing machine 100 shown in FIG. 6, for example, the printing paper 102 is supplied from the paper feeder 101 to the impression cylinder 104 a through the feed roller 103. On the other hand, the printing ink is supplied to the surface of the printing paper 102 interposed between the impression cylinder 104a and the blanket cylinder 106a through the plate cylinder 105a and the blanket cylinder 106a and used for surface printing. Further, the ink for printing on the back side is supplied to the back side of the printing paper 102 interposed between the other impression cylinder 104b and the blanket cylinder 106b through the other plate cylinder 105b and the blanket cylinder 106b for backside printing. Provided. The printing paper 102 on which both colors are printed in this way is sent to a transfer cylinder (intermediate cylinder) 107.

  Subsequently, it is sent to the same impression cylinder, blanket cylinder, etc., and printing of the second color is performed on the front surface and the back surface, respectively. In FIG. 6, only two colors are shown in order to avoid complication, but depending on the type of color to be printed, as many printing units as the number of impression cylinders and blanket cylinders are provided. Yes. The printing paper 102 for which necessary printing has been completed is sent to the intermediate cylinder 108 and then collected in the holder 109.

  However, when the paper printed between the blanket cylinders 106a and 106b and the impression cylinders 104a and 104b is sent from the impression cylinders 104a and 104b to the transfer cylinder 107, the ink on the printed paper is not dried. In addition, since the ink contacts the transfer cylinder 107, the ink adheres to the transfer cylinder 107, which causes reverse transfer onto the printing paper 102 and contaminates the printing surface.

As a means to remedy such problems, ceramics are sprayed on a metal substrate to form a porous ceramic layer, and a low surface energy resin such as a silicone-based resin is coated thereon to reduce the surface roughness. An intermediate cylinder having smooth irregularities of R _max 20 to 40 μm has been proposed (see, for example, Patent Document 1).

However, in such a technique, ceramic is sprayed on a metal plate to form a porous layer, and the surface is coated with a low surface energy resin such as a silicone resin, and the surface roughness is R _max 20 to 40 μm. By attaching a coated body having smooth irregularities to the impression cylinder or intermediate cylinder, the ink immediately after printing on the paper is prevented from adhering to the coated body, or glass beads are adhered on the synthetic resin film, By coating a silicone resin on top and mounting a cover with smooth irregularities with a surface roughness R _{max of 20 to} 150 μm on the intermediate cylinder so that the ink immediately after printing on the paper does not adhere to the cover It is.

Among the known techniques, by spraying a ceramic on a metal plate to form a porous layer, the low surface energy resin such as a silicone resin coated thereon, smooth the surface roughness R _max of 20~40μm If a cover with a rough surface (a schematic diagram of the surface roughness profile is shown in FIG. 4) is mounted on the impression cylinder or intermediate cylinder, when it is used as an impression cylinder, it prevents contamination of the jacket and makes solid printing of printed matter. This is very effective in preventing white spot troubles and inking properties on the printing surface. However, when this is used for a transfer cylinder, the surface roughness R _{max is} 20 to 40 μm. When the effect is small and the ink is used for a long time, the ink is deposited on the jacket surface, and it is necessary to perform cleaning once / day.

In order to reduce the jacket dirt, increasing the roughness of the ceramics sprayed, unevenness of the sprayed layer, the difference between R _max and R _z are increasingly large and the peak of the mountain becomes irregular, the R _max most Only a small number of high peaks will receive the paper surface, making it easier for solid print scratches to occur, resulting in large print quality defects.

  Furthermore, the biggest drawback of such transfer cylinders is that the surface is covered with a ceramic layer, which is an electrical insulator, so that it is easily charged by friction with the supplied printing paper. Has a problem that it is easy to cause unevenness of paper stacking in the delivery section.

Moreover, among the above-mentioned known techniques, glass beads are attached on a synthetic resin film, and a silicone resin is coated thereon, and a coated body having a smooth unevenness with a surface roughness R _{max of 20 to} 150 μm (surface roughness A schematic diagram of the profile is shown in Fig. 5.) When mounting to the transfer cylinder, the particle size of the glass beads is adjusted to a very narrow particle size width even if the surface roughness R _max is increased to 50 to 150 µm. By using a material to which a layer is further adhered, the heights of the ridges and depressions are uniform, and the shape of the projections of the ridges is a spherical surface, so that scratches on the printing surface are difficult to occur. Moreover, since the surface roughness can be increased, there is very little dirt on the covering, and there is no need for long-term cleaning.

  However, in this method, since the base material is a synthetic resin film and is an insulator, there is a problem that it is easy to be charged by rubbing with paper, and uneven paper stacking is likely to occur in the delivery section. Further, when the glass beads are adhered to the film, there is a problem that if the adhesive is made thin in order to leave the unevenness of the beads sufficiently, the glass beads are likely to fall off during use for a long time.

Despite these problems, it is widely used as an ink stain prevention material for transfer cylinders of various sizes, which is much cheaper than the former.
Japanese Patent Laid-Open No. 08-012151

  Accordingly, it is an object of the present invention to provide an improved sheet-fed offset printing machine transfer cylinder jacket.

  Another object of the present invention is to provide a sheet-fed offset printing press transfer cylinder jacket that has less surface contamination and is not charged by rubbing against printing paper.

  The above objects are achieved by the following (1) to (4).

(1) After thermally spraying a conductive metal on a metal plate to form a porous coating having a surface roughness R _max of 40 to 100 μm after spraying, the heights of the uneven portions of the sprayed coating are aligned. The surface roughness _Rz is 35 to 85 μm, and the surface is coated with a low surface energy resin so that the convex portion of the sprayed coating is thin, the concave portion is thick, and the unevenness of the sprayed coating remains. A sheet-fed offset printing machine transfer cylinder jacket having a composite coating film having a smooth surface roughness _Rz of 30 to 80 μm.

(2) The jacket for transfer cylinders according to (1), wherein an average peak pitch having a depth of 10 μm from R _max of the protrusions of the unevenness is present at a ratio of about 0.5 to 5.0 mm.

  (3) The jacket for transfer cylinders according to (1) or (2), wherein the low surface energy resin is a silicone resin.

  (4) A sheet-fed offset printing apparatus formed by winding the jacket according to any one of (1) to (3) around a transfer cylinder.

  The prior art, which was invented as a technique for preventing ink adhesion stains on the impression cylinders and transfer cylinders (intermediate cylinders) of offset printing machines, has less ink stains on the jacket as an impression cylinder cover, and also has a high print quality. It was also very good.

However, the surface roughness R _max 20 to 40 μm described in the claims of this technology is optimal for an impression cylinder jacket, but is not necessarily in an optimal range for a transfer cylinder (intermediate cylinder). There wasn't. That is, since R _max is set to a small level of 20 to 40 μm, a sufficient point contact effect is not exhibited from the surface of the jacket dirt, and it is necessary to clean the jacket once to several days. . On the other hand, the present invention sprays a conductive metal, forms a film having a surface roughness R _max after spraying of 40 to 100 μm, and then lightly polishes and raises the height of the uneven portion of the sprayed film. The surface roughness _Rz is 35 to 85 μm, and a release agent (silicone resin) is further coated on the surface so that the projections of the thermal spray coating are thin, the concaves are thick, and the projections and depressions of the thermal spray coating remain. The surface roughness Rz is 30 to 80 μm and the jacket has a composite coating film consisting of smooth irregularities, so that the ink stain on the jacket is much less than that of the prior art jacket and the cleaning frequency is once a month. Decreased to a degree.

In addition, when the thermal spray roughness is simply increased in the conventional technology, the jacket stain is reduced, but the difference between R _max and R _z is increased, so that scratches in the solid print portion are conspicuous, and high-quality printing on coated paper is not possible. Although this was not possible, the present invention is a light polishing after thermal spraying, and even though the roughness R _z is increased by evenly receiving the paper surface in many points by aligning the heights of the peaks of the convex portions. In addition, there are no noticeable scratches and print quality problems on coated paper do not occur.

Furthermore, compared with the prior art, the average peak pitch 10 μm deeper than R _max is greatly increased to about 1 piece from 0.5 mm to 5.0 mm, so that scratches in the solid print portion (not noticeable visually) , You can see with a 25X magnifier).

In the above prior art, a glass bead is bonded to a synthetic resin film to form a concavo-convex structure, and a silicone resin is coated on the concavo-convex structure, and the surface has a smooth concavo-convex surface roughness R _{max of 20 to} 150 μm. This is a technology to prevent ink adhesion stains by attaching to the intermediate cylinder, but this method is a problem of unevenness of paper in the paper delivery part due to friction with the paper, or insufficient adhesion strength of the glass beads Therefore, there is a problem that the replacement life is short (about 1 year) because the beads are likely to fall off after long-term use.

  On the other hand, in the present invention, the base material and the thermal spray material are all made of conductive metal, and there is no electrostatic trouble. In addition, by finding the optimum surface roughness region that can form a film with high adhesion strength without generating distortion on a very thin SUS plate of 0.25 mm by using the spraying method as the method of forming irregularities, the service life is There is an effect that it becomes much longer (estimated; 5 to 10 years). Compared with the glass bead coating, the initial cost is significantly increased, but there is a comprehensive improvement effect considering the drastic reduction in cleaning frequency and the prolongation of service life.

As described above, the sheet-fed offset printing machine transfer cylinder jacket according to the present invention sprays conductive metal on a substrate made of a metal plate material subjected to degreasing, blasting, etc., and the surface roughness of the sprayed coating is R. After forming a film having a _{maximum of} 40 to 100 μm, preferably 50 to 80 μm, the surface roughness is R _{z of} 35 to 85 μm, preferably 40 to 40 by lightly polishing and aligning the heights of the uneven portions of the thermal spray coating. Further, the surface roughness R _{z is} 30 to 80 μm by covering the surface with a release agent (low surface energy resin) so that the convex part of the thermal spray coating is thin, the concave part is thick, and the thermal spray coating remains uneven. Preferably, it is a metal jacket having a composite coating film of 35 to 65 μm and comprising smooth unevenness. FIG. 1 is a diagram schematically showing a cross-sectional structure after conductive metal spraying of such a transfer drum jacket according to the present invention, and FIG. FIG. 3 schematically shows a cross-sectional structure after the heights of the peaks are aligned and the surface is coated with a release agent, and FIG. 3 is a cross-sectional structure of the transfer drum jacket according to the present invention showing the surface roughness of the thermal spray coating. It is the figure which showed what increased the peak pitch of the peak of a convex part, and coat | covered the mold release agent after lightly grinding | polishing the sprayed coating.

  In these drawings, the vertical and horizontal scale ratios are exaggerated.

In order to obtain the transfer drum jacket of the present invention, first, as shown in FIG. 1, the conductive metal 2 is sprayed on the surface of the metal substrate 1 which has been roughened by degreasing and blasting. Then, the difference between the surface roughness R _max and R _z becomes larger. If the release agent 3 is coated as it is and used as a transfer drum jacket, the peaks of the R _max peaks will be uneven, and only the few peaks with the highest R _max will receive the paper surface. Is likely to occur, resulting in a large print quality defect. Therefore, FIG. 2 is an enlarged cross-sectional schematic view in which only a particularly high mountain is shaved by spraying lightly after thermal spraying, the peak height of the mountain is made uniform, and then a release agent is coated. As described above, since the rounded convex portions having the same height receive the paper surface evenly, even if the surface roughness is increased, scratches on the solid printed portion are hardly generated.

  Further, as shown in FIG. 1, the surface of the thermal spray coating has a roughness profile formed by combining short-period irregularities (pitch-wave irregularities) and even longer-period irregularities (swelled irregularities). However, by controlling the particle size composition of the thermal spray material, the peak pitch of the undulation-like irregularities is made to the optimum peak pitch as shown in FIG. 2 or FIG.

The ceramic spray jacket of the above prior art is a technology developed especially for the impression cylinder, and is a place where the blanket cylinder and the impression cylinder are pressed and printed on paper. Since there is a problem of white spots on the printed matter, the optimum roughness is limited to a smaller roughness range of R _max 20 to 40 μm as shown in FIG. It has revealed that _{R z} is in the range 30 to 80 [mu] m of. That is, if the R _z is less than 30 μm, the point contact effect is small, and if printing is continued for a long time, the ink adheres to and accumulates on the jacket, and the jacket needs to be cleaned once every few days. In addition, in order to obtain a roughness with _Rz exceeding 80 μm, it is necessary to use a material with a coarse particle size of the sprayed material. However, a thin metal plate having a thickness of about 0.2 to 0.35 mm is sprayed with a maximum particle size of 100 μm or more. Spraying the material is very difficult to work practically because of the large distortion of the metal material. Further, even if the surface roughness is made rougher than that, the effect of preventing the jacket stain is not improved so much. On the contrary, a problem that the scratches of the printed matter increase due to the coarseness is newly generated.

  On the other hand, the ceramic spray jacket of the prior art is sprayed with ceramics in consideration of wear resistance because printing is performed by pressing paper between the blanket cylinder and the impression cylinder, especially when used for an impression cylinder. However, in the case of a transfer cylinder, only the paper is guided and the load is not as great as that of the impression cylinder. Therefore, metal spraying is sufficient from the aspect of wear resistance, and the surface uneven structure is formed by conductive metal spraying. It is characterized by being formed.

  Further, since the glass bead film covering of the prior art coats the release agent 3 on the spherical surface of the glass bead 7 as shown in FIG. 5, the release agent 3 on the glass bead surface is easily worn out. . In order to prevent the release agent from being worn as much as possible, the adhesive 6 between the glass beads 7 and the film 5 is thinned, the unevenness between the glass beads 7 is deepened, and the release effect 4 is buried deeply in the recesses, thereby releasing the mold. The durability of the agent 3 is maintained, but the durability is still about one year.

  On the other hand, since the metal sprayed coating in the present invention has fine pores and fine pitch wave-like irregularities, the adhesion between the mold release agent and the metal sprayed coating has an anchor effect and is very strong. In addition, since the adhesion strength of metal spraying to the metal plate 1 in the present invention is much stronger than the adhesive strength between the film 5 and the glass beads 7, there is no problem that the uneven structure of the sprayed coating is damaged in a short period of time. Therefore, the durability is remarkably improved as compared with the glass bead film.

  Techniques for using ceramic spray jackets or glass bead films for impression cylinders and intermediate cylinders of printing presses are as previously described in detail in the prior art, but when identified as transfer cylinder jackets, prior art findings However, various problems occurred and the satisfactory function could not be exhibited.

  On the other hand, the present invention pursues an optimum surface roughness profile focused on the transfer cylinder and a manufacturing technique for realizing it, and as a new transfer cylinder jacket that does not exist in the prior art, ink adhesion contamination. This is a jacket for a sheet-fed offset printing press transfer cylinder that is less likely to be washed, is very durable, has little scratches on printed matter, and does not easily charge paper. .

  As the metal plate used in the present invention, any metal plate can be used. For example, stainless steel (SUS304), copper, nickel, aluminum alloy, etc. It is 0.1 to 0.5 mm, preferably 0.2 to 0.4 mm.

Moreover, as a metal used for thermal spraying, nickel chromium mixture (Ni 80 mass%, Cr 20 mass%), nickel-aluminum mixture (Ni 95 mass%, aluminum 5 mass%), aluminum, aluminum-zinc mixture (Al 13 mass%, Zn 87 mass%), zinc and the like, and a thermal spray material made of a mixture of metal and ceramics and having conductivity may be used. The particle size is usually 5 to 150 μm, preferably 10 to 100 μm. These are not limited to metal powder plasma spraying, and arc spraying using a metal wire can also be used.

The sprayed average film thickness is usually 40 to 100 μm, preferably 50 to 80 μm, and the sprayed amount is usually 400 to 1,000 g / m ² , preferably 500 to 800 g / m ² . In addition, the porosity of a metal sprayed film is 5-25% normally, Preferably it is 10-20%.

  Here, when a low surface energy resin 3 such as a silicone resin is coated and dried from above the metal spray coating 2, as shown in FIGS. 2 and 3, the surface of the metal spray layer 2 and A low surface energy resin layer 3 is formed in the hole. Since the low thermal energy resin 3 has the pitch-wave-like irregularities and is porous as described above, the low thermal energy resin 3 has an adhesive effect with the metal thermal spray layer 2 due to the anchor effect by entering these parts. The composite coating is well formed and the metal sprayed layer 2 and the low surface energy resin layer 3 form a composite coating.

  Further, the low surface energy resin 3 substantially covers the entire surface of the metal sprayed layer 2, but is thick on the undulating undulations and thinly attached to the undulating undulations. For this reason, the surface property is smoother than the state in which only the metal sprayed layer 2 is formed, but the unevenness caused by the metal sprayed layer 2 is not completely buried, and the undulating unevenness is generally maintained. A rough surface having smooth irregularities can be formed.

  For this reason, when the transfer cylinder according to the present invention comes into contact with the printing medium, it does not come into contact with the entire roller surface, but comes into contact only with the smooth protrusions as described above, and the surface has low surface energy properties. Due to the presence of the resin, ink transfer from the substrate is unlikely to occur, and the transferred ink also has a smooth uneven profile due to the surface being made of low surface energy resin. It can be easily removed by lightly wiping with a cloth impregnated with a solvent such as white kerosene.

  In addition, as described above, the low surface energy resin layer 3 is combined with the metal sprayed layer 2 and applied to the surface, so that even if it is used for a very long time, the entire surface is worn away. It does not occur, and only wear occurs at a very small portion, that is, the convex portion of the undulating unevenness. For this reason, the low surface energy of the roll surface is maintained over a long period of time, and the characteristics are hardly deteriorated. The undulations are expressed as “swells” for comparison with the concavo-convexs of finer pitches. However, the undulations are not visible at all, and therefore the resin layer 3 on the surface of the projections is not visible. Even when the metal sprayed layer 2 is exposed and the ink adheres and reversely shifts at this portion, there is no problem in print quality.

  When the metal sprayed layer is formed in this way, the low surface energy resin is impregnated and coated from the upper part by a method such as spraying, dipping, brushing, roller coating, etc., and dried and solidified at a predetermined temperature, and then the metal is sprayed. A low surface energy resin layer is formed on the surface of the thermal spray layer and in the pores. The low surface energy resin is not particularly limited as long as it has a low wettability with respect to the ink used and can form a film that is stable against a chemical used in the ink composition, preferably a high hardness film. However, usually, a silicone resin and a fluorine atom-containing resin are desirable, and a silicone resin is more desirable in terms of its hardness, workability, chemical stability, and the like.

  Silicone resins have a skeletal structure mainly composed of Si-O-Si bonds and organic groups, preferably methyl groups and / or phenyl groups, and more preferably methyl groups, after polymerizing and three-dimensionally after construction. And what is necessary is just to be able to form a stable cured film. The more methyl groups as the side chain, the lower the wettability with respect to the ink. However, from the viewpoint of improving the hardness, it is possible to increase the content of the cross-linked structure due to functional groups such as phenyl groups or vinyl groups. desired.

  In addition, the form at the time of construction is not particularly limited, for example, liquids such as oligomers and monomers, or solutions in which a resinous material is dissolved in an appropriate solvent, such as silicone varnish and silicone rubber Various known compositions that are classified and marketed can be appropriately selected and used. For example, a composition marketed as a varnish-type silicone release agent, or a composition similar thereto is available. Many are preferable from the viewpoints of workability and obtained film properties. As the silicone release agent, for example, a silicone mold or copolymer having a structure represented by the general formula (I) as a main component can be obtained as a commercial product.

(In the formula, each R independently represents a hydroxyl group, alkyl, aryl, alkenyl, halogen-substituted alkyl, halogen-substituted aryl, halogen-substituted alkenyl, preferably a methyl group, and n is 1 to 30000.)
However, as a matter of course, the silicone resin composition to be used is not limited to such a silicone release agent.

  Further, in such a silicone-based resin composition, if necessary, a filler such as silica fine particles for increasing the film hardness can be blended. It is necessary to have a particle size that can penetrate sufficiently.

  Also, as the fluorine atom-containing resin, a thermoplastic fluorine atom-containing resin such as polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride or the like is used, and it is applied after being suspended or swollen in an appropriate solvent, and heated to a melting temperature or higher. It is possible to use a dispersion processing method such as forming a film, but in order to form a film more reliably on the surface of the metal sprayed layer and in the pores, a small amount of hydroxyl groups and carboxylic acid groups are formed in the molecular chain. Thermosetting fluorine atom-containing resins that have functional groups such as, can be applied in liquid form, and are cured at room temperature or by crosslinking are desirable. For example, co-polymerization of fluoroethylene with acrylic acid and methacrylic acid Examples include coalescence.

  As described above, the thickness of the low surface energy resin layer to be formed on the surface of the metal spray layer is thick on the undulating undulations of the metal spray layer, while thinly attached to the undulating undulations of the metal spraying layer. It is difficult to specify as However, it is desirable that the entire surface of the thermal spray layer be deposited at a thickness of about 0.5 to 20 μm so as to cover the entire surface substantially and maintain the undulations of the metal thermal spray layer.

Thus jacket for sheet offset printing press transfer cylinder of the present invention obtained, the final surface properties is to have a smooth unevenness, it is desirable surface roughness R _z is about 30~80μm In addition, the smooth uneven projections on the final surface have an average peak pitch from R _max to a depth of 10 μm, for example, at a ratio of about 0.5 mm to 5.0 mm, more preferably about 0.7 mm to 3.5 mm. It is desirable to exist uniformly dispersed. The entire surface is formed by a dense low surface energy resin layer held as a composite coating film on the metal sprayed layer, and has low wettability to the ink used.

Here, the peak pitch is, for example, the highest peak (P ₇ ) when the roughness measurement length (L) is 12.5 mm in the distribution curve of the metal sprayed film having the surface roughness shown in FIG. Then, a line (A) is drawn at a depth of 10 μm and the number of peaks (P ₁ , P ₂ ... P _n ) crossing this line is counted. A value obtained by dividing the measured length (L) by the number of peaks (P _n ) is called a peak pitch.

  For example, when the number of peaks in FIG. 7 is 14, it is as follows.

Peak pitch = L / P _n = 12.5 mm / 14 = 0.89 mm
As a method of attaching the jacket of the present invention to the roller main body, a method by screwing or bonding, or a method in which the roller main body is provided with a clamping device or a winding device having a winding shaft can be employed.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
A 0.25 mm-thick SUS plate was sprayed with Ni—Cr having a thickness of 70 μm and an average particle size of 40 μm at a basis weight of 700 g / m ² . At that time, the surface roughness was R _max of 63.6 μm and Rz of 51.2 μm. The surface roughness after this was lightly polished with sandpaper and the peaks that protruded particularly high were shaved. The R _max was 55.1 μm and the R _z was 45.3 μm. From there, 100 parts by mass of silicone-based mold release agent (KS776L manufactured by Shin-Etsu Chemical Co., Ltd.), 300 parts by mass of toluene and 1 part of a curing catalyst (CAT-PL8 manufactured by Shin-Etsu Chemical Co., Ltd.) 13.8 g / m ² coating And a product surface roughness R _max of 49.4 μm, R _z of 41.8 μm, the peak pitch of the convex portion having a depth of 10 μm from R _max ; 1.875 mm, product thickness: 0.31 mm Manufactured. A schematic diagram of the surface roughness profile is shown in FIGS. For comparison, a jacket in which Ni-Cr was sprayed under exactly the same conditions as above and coated with a release agent without polishing was produced. In this case, the surface roughness of the product was R _max of 58.5 μm and R _z of 47.5 μm.

The surface roughness was measured at a measurement length generally used in JIS; 12.5 mm longer than 4.0 mm. (Measurement length: _Rz is about 5 μm larger than that measured at 4.0 mm).

  This transfer cylinder jacket was mounted on the first intermediate cylinder of the fifth to eighth colors of a sheet-fed offset double-sided printing machine (manufactured by Heidelberg, SM102; 4-color / 4-color duplex machine). Using this machine, solid printing (solid density: 2.2) was printed on the coated paper with the process ink of the 5th cylinder (black) (the 6th to 8th cylinders were only cylinder-filled).

  Although this printing is the test case in which scratches due to the intermediate cylinder jacket are most noticeable, scratches that can be visually discerned did not occur. In addition, this machine performed 60,000 high-quality catalog prints on the coated paper with 4 colors on the front and 4 colors on the coated paper, but there were no scratches that could be visually judged in the solid print section, and there was almost no ink stain on the jacket. There was no need to clean the transfer trunk jacket every day, and it was excellent. Furthermore, there was no generation of static electricity, so the paper alignment was sufficient.

  On the other hand, when a non-polished intermediate shell jacket manufactured for comparison was tested under the same printing conditions, there were many scratches that could be visually discerned, and there were practical problems.

Example 2
As in Example 1, Ni—Cr having a thickness of 50 μm was sprayed onto a 0.25 mm-thick SUS plate. The surface roughness at that time was R _max of 43.4 μm and R _z of 36.9 μm. Further, the same silicone release agent as in Example 1 was coated, and the product surface roughness R _max was 38.7 μm, R _z was 33.5 μm, the peak pitch of 10 μm depth was 0.522 mm, the product A transfer drum jacket having a thickness of 0.30 mm was manufactured. The roughness range of this specification is the same as that of the cover for the impression cylinder and the intermediate cylinder described in the prior art (Japanese Patent Laid-Open No. 8-12151, claim 12). A schematic diagram of the surface roughness profile is shown in FIG.

Using this transfer cylinder jacket, the same printing test as in Example 1 was performed. In this case, even without polishing after ceramics sprayed, the surface roughness of the _product, because _{R max} is small and 38.7Myuemu, scratches, such as no grinding of Example 1 (Comparative Example _{R max} is 58.5Myuemu) is Although it did not occur and could be used for high-quality multicolor printing on coated paper, it could be used for printing. However, in terms of ink stains on the transfer drum jacket, considerable jacket ink stains were seen after printing 10,000 sheets.

This surface roughness R _max 38.7 μm is close to the upper limit value of the optimum roughness range R _max 20 μm to 40 μm of the cover for the impression cylinder and intermediate cylinder described in the prior art (JP-A-8-12151, claim 12). However, when the roughness was further reduced, the ink stain on the jacket gradually increased, and the jacket washing frequency increased, which was not preferable.

The minimum surface roughness for the purpose of greatly reducing the frequency of cleaning the jacket as a transfer cylinder is 30 μm for R _z , and preferably 40 μm for R _z .

Example 3
As in Example 1, Ni—Cr having a thickness of 100 μm was sprayed on a SUS plate having a thickness of 0.25 mm. In this case, a film having a surface roughness R _max and a peak pitch of 10 μm depth larger than that of Example 1 was formed, and R _max was 96.5 μm and R _z was 70.6 μm. This was lightly polished with sandpaper, the surface roughness of after cutting the particularly high protruding _{mountain, R max} is 81.6μm, Rz was De' 60.4μm. Then, the same silicone release agent as in Example 1 was coated, and the product surface roughness R _max 76.6 μm, Rz 56.4 μm, 10 μm depth peak pitch 3.5 mm, product thickness; 0.33 mm A transfer drum was manufactured. A schematic diagram of the surface roughness profile is shown in FIG.

  A printing test was performed on this transfer drum jacket in the same manner as in Example 1.

As can be seen from Examples 1 to 3, the difference between R _max and R _z increases as the thermal spray roughness increases, and in the region where R _max is large as in Example 1 or Example 3, The transfer cylinder jacket coated with the silicone-based release agent without polishing was not practically usable because the scratches on the solid printing part were too conspicuous.

However, after the thermal spraying of Example 3, the jacket having a product roughness R _{max of} 76.6 μm and R _{z of} 56.4 μm, which was lightly polished and coated with a release agent, had almost no problem of scratches on the solid printing portion and had a depth of 10 μm. By further increasing the peak pitch, the number of scratches per unit area when observed with a 25-fold magnifier was greatly reduced, and good results were obtained.

Example 4
In order to further increase the roughness after thermal spraying, a 0.25 mm thick SUS plate was sprayed with a maximum spray particle size of 120 μm or more. Since the impact energy of the coarse particles on the SUS plate was large, the thickness was 0.25 mm. In the SUS plate, the distortion of the plate increased, causing a problem. When the spraying distance is increased in order to suppress the collision energy, the adhesion of the sprayed coating to the SUS plate is lowered, which is also problematic in practice.

As described above, it has been found that it is technically difficult to apply a surface roughness of R _{max of} 100 μm or more to a SUS plate having a thickness of about 0.25 mm by a thermal spraying technique. In addition, from the ink stain surface of the transfer drum jacket, the roughness R _max after spraying is 100 μm, the roughness R _{z is} 85 μm after polishing, and the roughness R _{z is} 80 μm after coating the release material, which is sufficient for preventing stains. I understood. That is, the upper limit of the optimum roughness as the transfer cylinder is R _max 100 μm after thermal spraying, R _z 85 μm after polishing, and R _z 80 μm after release agent coating.

  As the peak pitch with a depth of 10 μm is increased, the variation of the peak pitch increases, and control becomes difficult with the thermal spraying method. In the case where the average peak pitch is about 1 per 5.0 mm with a depth of 10 μm, the ink on the paper surface tends to adhere to the concave and convex portions where the peak width is wide, which causes jacket stains. Therefore, it has become clear that the upper limit of the average peak pitch at a depth of 10 μm should be about 1 per 5.0 mm, preferably about 1 per 3.5 mm.

Sectional drawing which shows the state which formed the metal spray coating on the metal plate in the manufacturing process of the transfer drum jacket by this invention. Sectional drawing which shows an example of the transfer cylinder jacket by this invention, after grind | polishing and aligning the height of a peak, and having coat | covered the mold release agent. Sectional drawing which is an example of the transfer cylinder jacket by this invention, Comprising: The peak pitch of the uneven | corrugated peak after metal spraying was widened. Sectional drawing which shows an example of the transfer cylinder jacket by the conventional ceramic spraying. Sectional drawing which shows an example of the transfer trunk | drum jacket by the conventional glass bead fill. 1 is a schematic cross-sectional view showing the structure of a sheet-fed offset double-sided printing machine. The graph which shows an example of the distribution curve for peak pitch measurement.

Explanation of symbols

1 metal plate,
2 Metal spray coating,
3 Release agent layer.

Claims (4)

Thermal spraying of conductive metal on a metal plate, then the surface roughness R _max after thermal spraying to form a porous coating is 40 to 100 [mu] m, surface roughness align the heights of the mountains of the uneven portion of the solution morphism film The degree of _Rz is 35 to 85 μm, and the surface is coated with a low surface energy resin so that the convex portion of the thermal spray coating is thin and the concave portion is thick and the irregularity of the thermal spray coating remains. A sheet-fed offset printing machine transfer cylinder jacket having a degree _Rz of 30 to 80 μm and a composite film composed of smooth irregularities. The jacket for transfer cylinders according to claim 1, wherein an average peak pitch having a depth of 10 μm from R _max of the convex portions of the unevenness is present at a ratio of about 0.5 mm to 5.0 mm. The jacket for a transfer cylinder according to claim 1 or 2, wherein the low surface energy resin is a silicone resin.   The sheet | seat offset printing apparatus formed by winding the jacket as described in any one of Claims 1-3 to a transfer cylinder.

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