Printing ink stain preventive sheet

Abstract

To provide an ink stain preventive sheet excellent in durability in using by winding around a paper feed cylinder or a guide roller of an offset printer.SOLUTION: A printing ink stain preventive sheet comprises: a top sheet (11) of a transparent synthetic resin film shaped into a state where projected and recessed parts are alternately continuous by embossing a large number of projected and recessed parts (16)(17) in which a mutual interval (d) between the projected parts (17) brought into point-contact with printing paper (P) or / and and a height (h) of the projected parts (17) are uneven; a base sheet (12) of a white synthetic resin film integrally stuck to the rear face via a transparent adhesive layer (18); and a separator (13) of a synthetic resin film stuck to the rear face via a re-peeling adhesive layer (19).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ink stain prevention sheet that is wrapped around a paper feed cylinder (paper transfer cylinder) or a guide roller of an offset printing press. [Background technology]

[0002] When printing multi-color materials using an offset printing press, the printing ink has a characteristic of drying slowly, and the drying speed is further affected by temperature and humidity.Therefore, when the printing paper is transported at high speed, the printing surface of the printing paper, where the printing ink is not yet completely dry, comes into contact with the paper feed cylinder (paper transfer cylinder) that sends the printing paper to the impression cylinder or double-cylinder drum in the case of a sheet-fed printing press, and with the continuous paper feed guide roller in the case of a rotary printing press.

[0003] This causes printing ink to adhere to the surface (outer periphery) of the paper feed drum or guide roller, and as the number of printed sheets increases and the length of the continuous paper increases, the printing ink accumulates, making the transportation of the printing paper unstable and also causing the adhered and accumulated printing ink to transfer to new printing paper being transported successively, staining the new printing paper, which can be particularly fatal for multi-color printed materials.

[0004] Conventional ink stain prevention sheets that are wrapped around the paper feed drum or guide roller are broadly divided into two types: those described in Patent Documents 1 to 3, in which a large number of small spheres (glass beads, acrylic beads, etc.) are adhered to the surface of a sheet substrate; and those described in Patent Document 4, in which tiny convex portions are formed by applying or printing an ultraviolet-curable varnish to the surface of a sheet substrate.In both cases, the small spheres or convex portions are made to come into point contact with the printing paper to prevent smearing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 61-31740 [Patent Document 2] Patent No. 3005620 [Patent Document 3] Patent No. 4822404 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-837 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of ink stain prevention sheets to which small spheres such as glass beads or acrylic beads are adhered, a large number of small spheres must be adhered to the surface of the sheet substrate with their exposed upper ends aligned. In particular, in the cases described in Patent Documents 2 and 3, it is necessary to cover the exposed surfaces of the small spheres with a cured resin layer, which increases the number of manufacturing steps and leads to higher costs.

[0007] In this case, in the ink stain prevention sheet described in Patent Document 1, the numerous glass beads are all the same size and are adhered with their exposed upper ends aligned, so that the points of point contact with the printing paper are always the same, and printing ink adheres and accumulates in a concentrated manner in those same points.

[0008] Furthermore, since the small spheres such as the glass beads are separate substances from the sheet substrate and are scattered independently on the surface of the sheet substrate, there is a risk that they will peel off from the sheet substrate early even if they are partially embedded (only the lower part) in the adhesive layer.

[0009] Furthermore, there are sharp corners in the gaps between the adjacent small balls, making it difficult to wipe off all the printing ink that has adhered and accumulated in the gaps, and the device cannot withstand long periods of continuous use.

[0010] On the other hand, even in the case of ink stain prevention sheets in which minute protrusions are formed on the surface of a sheet substrate using ultraviolet-curable varnish, the varnish must be applied or printed, which makes manufacturing complicated and also leads to high costs.

[0011] Furthermore, the convex portions formed by the application of the varnish are a separate material from the sheet substrate and are scattered independently on the surface of the sheet substrate, so they are also likely to peel off easily, resulting in poor durability.

[0012] Furthermore, the height of the convex portions is set to 10 μm to 50 μm, which is extremely low, so they are inferior in their support function of maintaining a point contact state that allows the printing paper to float, and they are still unable to reliably prevent printing ink from adhering.

[0013] Furthermore, the spacing between adjacent convex portions is sized at 50 μm to 150 μm, which is extremely narrow, making it difficult to wipe off printing ink that has adhered or accumulated in the gaps, and in that sense, it cannot withstand long-term continuous use. [Means for solving the problem]

[0014] The present invention aims to fundamentally solve such problems, and to achieve this aim, claim 1 provides an ink stain prevention sheet to be wrapped around a paper feed cylinder of a sheet-fed printing press or a guide roller of a rotary printing press,

[0015] a top sheet made of a transparent synthetic resin film on which a large number of uneven portions, in which the spacing between adjacent raised portions that come into point contact with the printing surface of the printing paper and / or the height of the raised portions are uneven, are embossed to form an alternating, continuous distribution of the uneven portions;

[0016] a base sheet made of a white synthetic resin film attached to the back surface of the top sheet via a transparent adhesive layer;

[0017] a separator made of a synthetic resin film or paper attached to the back surface of the base sheet via a removable adhesive layer,

[0018] The separator is characterized in that half cuts are made at both ends of the separator at positions that will be cut off for winding around the paper feed cylinder or guide roller of the printing press, for peeling off the ends.

[0019] In claim 2, grid lines are printed on the back of the base sheet as cutting position guide indicators for the length and / or width dimensions required for wrapping around the paper feed cylinder or guide roller of the printing press, and

[0020] A separator made of a transparent synthetic resin film is attached to the back surface of the base sheet via a re-peelable transparent adhesive layer.

[0021] Claim 3 is characterized in that the surface of the top sheet is coated with a UV-curable release agent layer.

[0022] In claim 4, the height of the raised portion is set to 1.5 to 2.5 times the constant thickness of the top sheet,

[0023] The boundary (corner) where the convex portion that rises in a conical shape with an acute angle of approximately 90 degrees or less intersects with the concave portion that sinks in an inverted truncated cone shape with an approximately flat groove bottom is curved at an obtuse angle that does not create a ridge line.

[0024] Claim 5 is characterized in that a total of three layers, namely, a top sheet, a base sheet which is thicker than the top sheet, and a separator which is thinner than the top sheet, are all made of polyethylene terephthalate (PET) resin film. [Effects of the Invention]

[0025] According to the above configuration of claim 1, the top sheet of the ink stain prevention sheet, which is made of a transparent synthetic resin film, is formed with a large number of uneven portions with convex portions that come into point contact with the printing surface of the printing paper, in an alternating, continuous distribution by embossing, so that it is possible to reliably prevent the printing paper from being soiled by the adhesion of printing ink, and further, it is possible to manufacture the sheet extremely easily without requiring small spheres such as glass beads or ultraviolet-curing varnish, or the adhesion of the spheres to the sheet substrate, or the application or printing of varnish, as in the prior art mentioned at the beginning, and it is therefore possible to achieve excellent mass production efficiency.

[0026] Furthermore, unlike small spheres such as glass beads adhered to the surface of the sheet substrate in an independently scattered manner, or convex portions made of varnish applied or printed in a similarly independently scattered manner, there is no risk of these separate substances peeling off from the sheet substrate, and the sheet substrate can withstand long periods of continuous use.

[0027] In particular, the unevenness formed on the top sheet itself is such that the spacing between adjacent convex portions and / or the height of the convex portions are set to be uneven (irregular or irregular), so that the points of contact with the printing paper are not always constant in the same place, and the adhesion of printing ink that tends to concentrate in a fixed place can be naturally and effectively dispersed, further improving durability in this respect as well.

[0028] Furthermore, a synthetic resin film base sheet is bonded to the backside of the top sheet via a transparent adhesive layer, which allows the ink stain prevention sheet to have an appropriate film thickness, making it easier to wrap around the paper feed cylinder (paper transfer cylinder) or guide roller of an offset printing machine and contributing to its convenience in handling.

[0029] Furthermore, since the base sheet is made of a white synthetic resin film, when the top sheet of the ink stain prevention sheet that is wrapped around the paper feed drum or guide roller is viewed from the front side, the white base sheet serves as a background, so to speak, and the state and degree of staining caused by printing ink adhering to the surface of the top sheet can be accurately grasped, which has the effect of allowing the ink stain prevention sheet to be replaced in a timely manner.

[0030] Furthermore, the separator (release sheet) attached to the back surface of the base sheet via a re-peelable adhesive layer has half cuts at both ends to allow for easy peeling. This allows printing companies to peel off both ends of the separator from the half cut positions without the need for tools, and the exposed adhesive layer can be used to quickly and conveniently attach the separator to the paper feed cylinder or guide roller of an offset printing machine.

[0031] In this case, if the configuration of claim 2 is adopted, the grid lines (vertical and horizontal orthogonal lines / grid lines) printed on the back surface of the base sheet as cutting position guide indicators for the ink stain prevention sheet can be seen without any obstruction from the back side of the separator made of a transparent synthetic resin film attached to the back surface of the base sheet via a transparent adhesive layer, so that the ink stain prevention sheet can be cut along the grid lines from the back side according to the length and / or width dimensions required to wrap it around the paper feed cylinder or guide roller of the offset printing machine, making the wrapping operation easy and accurate, which is extremely convenient.

[0032] Furthermore, if the configuration of claim 3 is adopted, by coating the top sheet with a UV-curable release agent layer before embossing, it is possible to prevent the printing ink from adhering to the surface of the top sheet, and even if it does adhere, it can be easily wiped off.

[0033] In this regard, if silicone is used as the surface resin hardening layer, there is a risk that it will peel off when wiped, as silicone is a solvent.However, a release agent layer that is UV-curable and quickly hardens when exposed to ultraviolet light after coating will not peel off even when wiped with a solvent, making it effective.

[0034] In particular, if the configuration of claim 4 is adopted, the height of the raised portion is dimensioned to be 1.5 to 2.5 times the constant thickness of the top sheet, and height variations (unevenness / irregularity) are given within that numerical range, which provides excellent support function for maintaining a point contact state that lifts the printing paper, and has the effect of more completely preventing the adhesion of printing ink.

[0035] Furthermore, the boundaries (corners) where the convex portions, which rise in a conical shape at an acute angle of approximately 90 degrees or less, intersect with the concave portions, which are concave in an inverted truncated cone shape with a nearly flat groove bottom, are curved at an obtuse angle that does not create a ridge line by the etched embossing roll, and since there are no angular corners or sharp intersections, there is no risk of damaging the printing paper, and printing ink that has adhered to or accumulated in the concave portions can be quickly wiped away completely, even to the corners, using a solvent or cleaning oil.

[0036] Furthermore, if the configuration of claim 5 is adopted, the three layers that make up the ink stain prevention sheet are all made of polyethylene terephthalate (PET) resin film, so not only is it resistant to solvents and cleaning oils that are used to wipe off printing ink (oil and chemical resistance), but even when exposed to heat during continuous high-speed printing, the top sheet, base sheet, and separator will not shrink differently from each other or undergo other irregular deformation, and there is no risk of delamination. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a schematic cross-sectional view of an entire printing ink stain prevention sheet according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing the embossing process on the top sheet and a partially enlarged plan view of the processed state. [Figure 3] FIG. 10 is a schematic side view showing a point contact state between the protrusions of the top sheet and the printing paper. [Figure 4] 3 is a partially enlarged view of the uneven portion extracted from the Z portion of FIG. 2. FIG. [Figure 5] FIG. 10 is an explanatory diagram showing the peeling action from half cuts provided at both ends of the separator. [Figure 6] 1 is a perspective view showing a state in which an ink stain prevention sheet is wrapped around a paper feed cylinder of a printing press. [Figure 7] 1 is an explanatory diagram showing the main components of an offset multicolor sheet-fed printing press. FIG. [Figure 8] FIG. 2 is a bottom view of the ink stain prevention sheet according to the first modified embodiment of the present invention, seen from the back side. [Figure 9] FIG. 2 is a schematic overall cross-sectional view of an ink stain prevention sheet according to a second embodiment of the present invention, corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0038] Below, we will explain a preferred embodiment of the present invention as applied to a paper feed cylinder (paper transfer cylinder) of an offset sheet-fed printing press, based on the drawings, but as already mentioned, it can also be applied to a guide roller of an offset rotary printing press.

[0039] As is clear from the overall schematic cross-sectional view of Figure 1, the printing ink stain prevention sheet (A) according to a preferred embodiment of the present invention is made up of a total of three layers, namely, a top sheet (sheet substrate) (11), a base sheet (12), and a separator (release sheet) (13), which are laminated together.

[0040] Of the components, the top sheet (11) is made of a transparent polyester resin film with a smooth surface, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polybutylene terephthalate (PBT), or a transparent polyolefin resin film, such as polypropylene (PP) or polyethylene (PE), or other flexible transparent synthetic resin film. It is particularly preferable to use a polyethylene terephthalate (PET) resin film with a thickness (t1) of 50 μm to 100 μm, especially a thickness (t1) of 75 μm, which has excellent transparency, heat resistance, oil resistance, strength, etc.

[0041] Then, as shown in Figure 2, the top sheet (11) is passed between a metal embossing roll (14) having an uneven shape (preferably a grained pattern) in which the corners and edges have been chamfered (so-called rounded) by etching, and a rubber backup roll (15), and the top sheet (11) is embossed with numerous uneven portions (16) and (17) in an alternating, continuous distribution, and the raised portions (17) are shaped so that they can come into point contact with the printing surface of the printing paper (P) in an offset printing press, as shown in Figure 3.

[0042] In this case, as shown in the partially enlarged cross-sectional view of Figure 4, the protrusion height (h) of the convex portion (17) in the concave-convex portions (16) (17) is set to 112.5 to 187.5 µm, preferably 140 to 160 µm, which is 1.5 to 2.5 times the constant thickness (t1) (preferably 75 µm as exemplified above) of the flexible synthetic resin film that is the top sheet (11).

[0043] If the protrusion height (h) is within this numerical range, the convex portions (17) of the top sheet (11) that come into point contact with the printing surface of the printing paper (P) can keep the printing surface in a stably raised and supported state, and furthermore, due to the uneven shape of the etched embossing roll (14) and the flexibility of the top sheet (11) itself, the convex portions (17) form a conical surface with an acute angle (α) of approximately 90 degrees or less as shown in Figure 4, but the apex (17a) is a convex curved surface that is not sharpened, so there is no risk of damaging the printing paper (P).

[0044] Furthermore, the distance (d) between adjacent convex portions (17) that come into point contact with the printing surface of the printing paper (P) is set to a dimension greater than the protruding height (h) of the convex portions (17), preferably 0.5 to 1.0 mm.

[0045] If the spacing (d) is within this range, the recesses (16) of the top sheet (11) are also recessed into an inverted truncated cone shape with a nearly flat groove bottom surface (16b) as shown in Figure 4 due to the uneven shape of the etched embossing roll (14), and the boundary (corner) (16c) that intersects with the conical protrusion (17) is formed as a concave curved surface with an obtuse angle (β) that does not form a ridge line. This also makes it possible to easily wipe off printing ink that has adhered to and accumulated in the recesses (16) without leaking, using cleaning oil or solvent.

[0046] Furthermore, for the numerous convex portions (17), the mutual intervals (d) between adjacent convex portions (17) may all be made uniform and substantially the same width, while the protrusion heights (h) of the convex portions (17) may be made unevenly high and low within the above numerical range (112.5 to 187.5 μm as exemplified above); preferably, the protrusion heights (h) of the convex portions (17) may all be made uniform and substantially the same width, while the mutual intervals (d) between adjacent convex portions (17) may be made unevenly (irregularly / unevenly) wide and narrow within the above numerical range (0.5 to 1.0 mm as exemplified above); or both the mutual intervals (d) between adjacent convex portions (17) and the protrusion heights (h) may be made unevenly different.

[0047] In such a case, the printing surface of the printing paper (P) is supported evenly by the numerous protrusions (17) that protrude from the top sheet (11), so to speak, and is raised. However, the points where the protrusions (17) come into point contact with the printing surface are not always constant, and the adhesion and accumulation of printing ink that would otherwise concentrate in those fixed points can be dispersed, thereby extending the useful life of the ink stain prevention sheet.

[0048] In particular, as in the preferred example described above, if the protrusion height (h) of the convex portions (17) is set to be substantially the same and uniform, while the mutual spacing (d) between the convex portions (17) is varied non-uniformly (at random) within the above numerical range (for example, 0.5 to 1.0 mm), the numerous convex portions (17) can stably support the printing surface of the printing paper (P) in a point contact state, while preventing the concentrated adhesion and accumulation of printing ink in a fixed location.

[0049] Next, the base sheet (12) is made of a white synthetic resin film, and it is particularly preferable to use a polyethylene terephthalate (PET) resin foam, which develops a white color. The thickness (t2) of the base sheet (12) is thicker than the thickness (t1) of the top sheet (11), for example, 100 to 125 μm, preferably 100 μm, and is integrated with the back surface of the top sheet (11) by using a transparent adhesive layer (18) as shown in Figure 1.

[0050] Therefore, when the ink stain prevention sheet (A) is viewed through the front side of its transparent top sheet (11), it appears to be the white color of the base sheet (12), and with this white color as a background (ground color), the state and degree of staining caused by printing ink adhering to the surface (uneven portions) (16) (17) of the top sheet (11) can be clearly seen, which is useful for determining when to replace the ink stain prevention sheet (A) with a new one.

[0051] Furthermore, the separator (release sheet) (13) is made of a synthetic resin film or paper, preferably a polyethylene terephthalate (PET) resin film having a thickness (t3) (for example, 15 to 50 μm) thinner than the thickness (t1) of the top sheet (11), and is attached to the back surface of the base sheet (12) using a removable adhesive layer (19) as shown in FIG. 1.

[0052] Furthermore, at the positions of the separator (13) that will be the ends (top and bottom) (13f) (13r) to be separated for wrapping around the paper feed cylinder (20) of an offset printing machine, half cuts (21) are provided for peeling off the ends (13f) (13r) as shown in Figure 5.

[0053] A printing company using the ink stain prevention sheet (A) can peel off both ends (13f) (13r) of the separator (13) from the line where the half cut (21) was made without the need for tools, and then use the exposed removable adhesive layer (19) to attach the ink stain prevention sheet (A) to the surface (outer peripheral surface) of the paper feed drum (20) in a wrapped state as shown in Figure 6.

[0054] FIG. 7 is an explanatory diagram of the state of use in which the ink stain prevention sheet (A) is wrapped around and fixed to the paper feed cylinder (paper transfer cylinder) (20) of an offset multicolor sheet-fed printing press, where (22) indicates the plate cylinder of the printing press, (23) the blanket cylinder, (24) the impression cylinder, and (25) the double-cylinder drum. Printing is performed on the printing paper (P) between the blanket cylinder (23) and the impression cylinder (24), so the printed surface of the printing paper (P) comes into contact with the surface (outer periphery) of the paper feed cylinder (20).

[0055] However, since the ink stain prevention sheet (A) having the above-mentioned configuration is wrapped around and attached to the contact surface of the paper feed cylinder (20) with the printing surface, the printing surface of the printing paper (P) being conveyed successively only comes into point contact with the convex portions (17) of the concave and convex portions (16) and (17) embossed on the top sheet (11) of the ink stain prevention sheet (A).

[0056] As a result, adhesion of printing ink from the printing surface of the printing paper (P) to the paper feed cylinder (20) is extremely reduced, and as a result, the adhering printing ink is not transferred to the subsequent new printing paper (P), and it is possible to reliably prevent the printing paper (P) from being soiled by printing ink.

[0057] In this sense, the ink stain-resistant sheet (A) can be used for a long period of time. However, if printing ink adheres to and accumulates on the surface (uneven portions) (16) (17) of the top sheet (11), particularly in the recesses (16), during use, the sheet can be reused repeatedly by wiping off the printing ink with cleaning oil or solvent.

[0058] Furthermore, Figure 8 is a bottom view of the ink stain prevention sheet (A) according to the first modified embodiment of the present invention, seen from the back side. It is preferable to print grid lines (vertical and horizontal orthogonal lines / grid lines) (26a) (26b) on the back side of the base sheet (12) illustrated in Figure 1, which serve as cutting position guide indicators for the length dimension (e.g., 800 mm) (L) and / or width dimension (e.g., 1050 mm or 1150 mm) (W) required to wrap the ink stain prevention sheet (A) around the paper feed cylinder (20) of an offset printing press.

[0059] Moreover, it is desirable to use a polyethylene terephthalate (PET) resin film or other transparent synthetic resin film as the separator (13), similar to the top sheet (11), and also to use a transparent re-peelable adhesive layer (19) for bonding the transparent separator (13) to the back surface of the base sheet (12).

[0060] In this case, the illustrated grid lines (26a) (26b) consist of thick grid lines (26a) with wide, regular intervals (for example, 50 mm) and thin grid lines (26b) with narrow, regular intervals (for example, 10 mm), and both are arranged so as to be perpendicular to the width direction (horizontal direction) of the ink stain prevention sheet (A) and the winding length direction (vertical direction).In short, any indication that can function as the cutting position guide indicator is sufficient, so for example, parallel lines that serve as cutting position guide indicators for the width dimension (W) of the paper feed drum (20) can be omitted regardless of their thickness.

[0061] In any case, according to the configuration of the first modified embodiment, the grid lines (26a) and (26b) for guiding the cutting position of the ink stain prevention sheet (A) printed on the back surface of the base sheet (12) can be seen without any hindrance from the back side of the separator (13) made of a transparent synthetic resin film attached to the back surface of the base sheet (12) via a transparent removable adhesive layer (19). Therefore, a printing company can cut the ink stain prevention sheet (A) along the grid lines (26a) and (26b) to fit the width dimension (W) and / or winding length dimension (L) of the paper feed cylinder (20) of their offset printing press. In combination with the half cut (21) made on the separator (13) in Figure 1, this allows the sheet to be quickly and accurately attached in a wound state around the paper feed cylinder (20) of the printing press, further improving convenience.

[0062] The ink stain prevention sheet (A) is sold as a roll product with a suitable width (W) of, for example, 1050 mm, 1150 mm, or other wider width, and a winding length of, for example, 10 m, and the printing company that purchases it cuts it to fit the paper feed cylinder and guide rollers of the offset printing machine they use.

[0063] FIG. 9 is a schematic overall cross-sectional view corresponding to FIG. 1 showing an ink stain prevention sheet (A) according to a second embodiment of the present invention. The surface of a top sheet (11), preferably a polyethylene terephthalate (PET) resin film having excellent transparency or other smooth top sheet, may be coated with a thin UV-curable release agent layer (27) of, for example, 1 to 2 μm, and the coated top sheet (11) may be processed into the shape shown in FIG. 9 using an embossing roll (14) similar to that shown in FIG. 1.

[0064] In this way, the release agent layer (27) that is hardened by exposure to ultraviolet light after coating will more effectively prevent the printing ink from adhering to the surface (uneven portions) (16) (17) of the top sheet (11), and even if the printing ink does adhere or accumulate, it can be easily and reliably wiped off with a solvent or cleaning oil.

[0065] Furthermore, since the other configurations and usage states of the first and second modified embodiments in Figures 8 and 9 are substantially the same as those of the embodiments described in Figures 1 to 7, the same symbols as those in Figures 1 to 7 are simply used in Figures 8 and 9, and detailed explanations thereof will be omitted. [Explanation of symbols]

[0066] (11) Top sheet (sheet substrate) (12) Base sheet (13) Separator (release sheet) (13f)(13r) Both ends of separation (14) Embossing roll (15) Backup roll (16) Recess (16b)... Groove bottom surface (16c)...Boundary (corner) (17) Convex part (17a) Vertex (18)...Adhesive layer (19) Removable adhesive layer (20) Paper feed cylinder (paper transfer cylinder) (21) Half cut (26a)(26b)...grid line (27) UV-curable release agent layer (A) Ink stain prevention sheet (d) Interval between convex portions (h) Height of the protruding part (L) Length dimension (P)...Printing paper (W) Width dimension (α) Acute angle (vertex angle) (β)...obtuse angle

Claims

1. An ink stain prevention sheet (A) to be wrapped around a paper feed cylinder (20) of a sheet-fed printing press or a guide roller of a rotary printing press, a top sheet (11) made of a transparent synthetic resin film on which a large number of uneven portions (16) (17) are formed by embossing, with the uneven portions (16) (17) having uneven spacings (d) between adjacent raised portions (17) that come into point contact with the printing surface of the printing paper (P) and / or uneven heights (h) of the raised portions (17) being formed in an alternating, continuous distribution state; a base sheet (12) made of a white synthetic resin film attached to the back surface of the top sheet (11) via a transparent adhesive layer (18); and a separator (13) made of a synthetic resin film or paper attached to the back surface of the base sheet (12) via a removable adhesive layer (19), The ink stain prevention sheet for printing is characterized in that half cuts (21) for peeling off both ends (13f) (13r) are made at positions on the separator (13) that will become both end parts (13f) (13r) to be cut off for winding around the paper feed cylinder (20) or guide roller of the printing machine.

2. Grid lines (26a) and (26b) are printed on the back surface of the base sheet (12) to serve as cutting position guide indicators for the length dimension (L) and / or width dimension (W) required for winding the sheet around a paper feed cylinder (20) or a guide roller of a printing press, and 2. The printing ink stain prevention sheet according to claim 1, wherein a separator (13) made of a transparent synthetic resin film is attached to the back surface of the base sheet (12) via a re-peelable transparent adhesive layer (19).

3. 3. The printing ink stain prevention sheet according to claim 1, wherein the surface of the top sheet (11) is coated with a UV-curable release agent layer (27).

4. The protruding height (h) of the convex portion (17) is dimensioned to be 1.5 to 2.5 times the constant thickness (t1) of the top sheet (11), and 4. A printing ink stain prevention sheet according to claim 1 or 3, characterized in that the boundary (16c) where the convex portion (17) that protrudes in a conical shape at an acute angle (α) of approximately 90 degrees or less intersects with the concave portion (16) that is concave in an inverted truncated cone shape with an approximately flat groove bottom surface (16b) is curved at an obtuse angle (β) that does not create a ridge line.

5. 5. A printing ink stain prevention sheet according to claim 1, 2, 3 or 4, characterized in that the three layers, namely the top sheet (11), the base sheet (12) which is thicker than the top sheet (11), and the separator (13) which is thinner than the top sheet (11), are all made of polyethylene terephthalate (PET) resin film.

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