Press-bonding sheet and manufacturing method for press-bonding sheet

Abstract

To provide a press-bonding sheet in which an image is printed on a press-bonding face part using a toner, having a composition that prevents local peeling and damage during opening.SOLUTION: A press-bonding sheet 1 includes a second paper piece 12 separably press-bonded via an adhesive layer 39 onto a press-bonding face part 21 of a first paper piece 11. A colored image is formed by fixing a colored toner on the press-bonding face part 21, and a regular colorless pattern is formed by fixing a colorless toner that does not affect a paper color of the first paper piece 11 on a non-formation portion 31 of the colored image. By fixing the toner on both a formation portion 30 and the non-formation portion 31 of the colored image, an irregularity in adhesive strength of the press-bonding face part 21 is reduced, which prevents the local peeling and the damage during opening.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet for a pressure-sensitive postcard or the like, and a method for producing the same. [Background technology]

[0002] In the manufacturing process of sealed postcards, it has been proposed to simultaneously perform the process of printing an image with toner on the pressed surface of a piece of paper and the process of laminating powder adhesive on the pressed surface using an image forming device equipped with a cartridge filled with toner and a cartridge filled with powder adhesive. In sealed postcards manufactured in this manner, the adhesive strength between the pieces of paper tends to be reduced in the areas where the toner image is formed, and the adhesive strength on the pressed surface is uneven, which can lead to localized peeling or damage when opened. For this reason, it has been proposed to apply more adhesive in areas where a greater amount of toner is fixed, in order to compensate for the reduced adhesive strength due to the toner (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-152378 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as in Patent Document 1, it is not easy to compensate for the decrease in adhesive strength due to toner fixation by adjusting the amount of adhesive. This is because the range over which adhesive strength can be adjusted by adjusting the amount of adhesive is limited. Furthermore, since the amount of adhesive needs to be adjusted precisely to match the toner image printed on the pressure-bonding surface, this is difficult to implement in manufacturing sites where the toner image printed on the pressure-bonding surface is frequently changed.

[0005] The present invention was made in consideration of the current situation, and aims to provide a configuration for pressure-sealed sheets such as pressure-sealed postcards, which have images printed with toner on the pressure-sealed surface, that is less likely to peel off locally or be damaged when opened. [Means for solving the problem]

[0006] The present invention is a pressure-bonded sheet in which a second piece of paper is releasably bonded to the pressure-bonded surface of a first piece of paper via an adhesive, characterized in that a colored image is formed on the pressure-bonded surface by fixing colored toner, and a regular colorless pattern is formed in the areas where the colored image is not formed by fixing colorless toner that does not affect the paper color of the first piece of paper.

[0007] That is, in this configuration, by fixing toner to both the color image formation area and the non-formation area, the variation in adhesive strength between the color image formation area and the non-formation area is reduced. Even if the bonding surface becomes somewhat more difficult to adhere due to the fixing of colorless toner in addition to color toner, the overall adhesive strength of the bonding surface can be adjusted by adjusting the pressure applied during bonding, etc. Therefore, if the variation in adhesive strength between the bonding surface is reduced, by bonding the pieces of paper together under appropriate bonding conditions, the number of areas where the adhesive strength between the pieces of paper is excessive or insufficient can be reduced. In particular, the present invention can significantly reduce the variation in adhesive strength compared to reducing the variation in adhesive strength by adjusting the amount of adhesive, as described above. Therefore, according to the present invention, localized peeling on the bonding surface and damage when opening the pressure-bonded sheet are less likely to occur. Furthermore, since the pattern of colorless toner formed in the non-forming areas can be easily changed to match the colored image, the present invention can be easily implemented even in manufacturing sites where the colored image formed on the pressure-bonding surface is frequently changed. Furthermore, in the case of press-bonded postcards on which images are printed using toner, the ease with which the pieces of paper adhere varies greatly depending on the number of toner images. Therefore, in conventional configurations, in order to press the pieces of paper together with an appropriate adhesive force, the press conditions are adjusted depending on the number of toner images printed on the press surface. In contrast, in the press surface of the present invention, toner is also applied to areas where no color images are formed, so the ease with which the pieces of paper adhere together does not vary significantly depending on the number of color images. Therefore, according to the present invention, the effort required to adjust the press conditions depending on the number of color images can be reduced compared to conventional configurations.

[0008] The colored image of the present invention is sufficient as long as it can be visually recognized as a colored toner image against the paper color of the piece of paper, and includes not only characters and figures but also background images. Furthermore, the colored image may be formed by solid coloring or by halftone dots. On the other hand, the colorless pattern of the present invention is substantially colorless and transparent or the same color as the paper color of the piece of paper, and is difficult to visually recognize as a toner image. In other words, the colored toner of the present invention is a toner of a color different from the paper color of the piece of paper, and the colorless toner is a colorless and transparent toner or a toner of substantially the same color as the paper color.

[0009] Although the compositions of the color toner and colorless toner according to the present invention are not particularly limited, it is desirable that they contain a common thermoplastic resin to make their physical properties similar. This is because it makes it easier to reduce variations in adhesive strength between areas where a color image is formed and areas where it is not formed, and also makes it easier to simultaneously form a color image and a colorless pattern on a pressure-bonding surface using an image forming device such as a laser printer. Examples of thermoplastic resins that can be contained in the color toner and colorless toner include polyester resins and styrene-acrylic resins. Note that the toner according to the present invention does not include adhesives that soften under pressure to exert adhesive strength, such as pressure-bonding adhesives.

[0010] The adhesive of the present invention is not particularly limited, but is preferably colorless and transparent. Suitable materials include those containing, as a main component, a pressure-responsive resin that softens under pressure to exert adhesive strength. In particular, the adhesive of the present invention is preferably one that can be fixed in powder form to the pressure-bonded surface of a piece of paper using an electrophotographic method, similar to colored and colorless toners. Examples of such adhesives include those containing a known pressure-responsive resin that is primarily composed of a styrene resin and an acrylic ester resin. While powder adhesives that can be fixed using an electrophotographic method are sometimes called "pressure-bonded toners," the colored and colorless toners of the present invention do not contain a pressure-responsive resin as a main component and do not exert adhesive strength under pressure. In this respect, powder adhesives that can be fixed using an electrophotographic method are distinguished from colored and colorless toners.

[0011] In the present invention, it is proposed that the colorless pattern be a mesh pattern. In this configuration, the adhesive strength in the areas where the color image is not formed is uniform, thereby further reducing variations in adhesive strength in the pressure-bonding surface.

[0012] In addition, the present invention proposes a configuration in which the colorless pattern is not formed in the area where the colored image is formed, because colored toners are fixed in the area where the colored image is formed, so there is little need to fix colorless toner in the area where the colored image is formed, and also, if colorless toner is fixed in the area where a large amount of colored image is fixed, it becomes difficult to reduce variations in adhesive strength.

[0013] The present invention also proposes a configuration in which the colorless pattern is formed over substantially the entire area of ​​the color image non-forming area, which significantly reduces variations in adhesive strength between the color image forming area and the color image non-forming area.

[0014] In the present invention, the colorless pattern is preferably formed in the areas where the colored images are not formed at a printing rate of 10 to 50%. If the printing rate of the colorless toner in the areas where the colored images are not formed is too low or too high, sufficient effects may not be obtained. Furthermore, if the printing rate of the colorless toner is too high, the cost of the colorless toner increases. According to the inventor's research, at least if the printing rate of the colorless toner in the areas where the colored images are not formed is in the range of 10 to 50%, the variation in adhesive strength between the areas where the colored images are formed and the areas where the colored images are not formed can be suitably reduced.

[0015] As another aspect of the present invention, a method for manufacturing a pressure-bonded sheet in which a second piece of paper is releasably bonded to the bonding surface of a first piece of paper via an adhesive is proposed, comprising a first step of fixing toner to the bonding surface using an electrophotographic method and laminating adhesive on top of the toner, and a second step of superimposing the second piece of paper on the bonding surface and bonding it to the first piece of paper, wherein in the first step, a colored image is formed on the bonding surface using a colored toner, and a regular colorless pattern is formed in the areas where the colored image is not formed using a colorless toner that does not affect the paper color of the first piece of paper.

[0016] In this manufacturing method, the colored image and the colorless pattern according to the present invention can be formed in a single process using a laser printer or the like. [Effects of the Invention]

[0017] As described above, according to the present invention, in a pressure-bonded sheet such as a pressure-bonded postcard on which an image is printed with toner on the pressure-bonded surface, localized peeling and damage when opened are less likely to occur compared to conventional configurations. [Brief explanation of the drawings]

[0018] [Figure 1] 1A and 1B are a front view and a back view, respectively, of a pressure-sealed postcard 1 according to an embodiment of the present invention. [Figure 2] 1A is a diagram of the surface of the inside surface 17 of the pressure-bonded postcard 1, and FIG. 1B is an explanatory diagram showing the image forming area 30 shaded in black. [Figure 3] 1A and 1B are explanatory views showing the cross-sectional structure of the crimped surfaces 21 and 22 of a crimped postcard 1, in which (A) shows the crimped state of the crimped postcard 1 and (B) shows the crimped postcard 1 in an opened state. [Figure 4] FIG. 2 is an explanatory diagram showing an overview of an image forming apparatus 40. [Figure 5] 10 is a table showing the results of an evaluation test. DETAILED DESCRIPTION OF THE INVENTION

[0019] The embodiments of the present invention will be described with reference to the following examples. In the following examples, the first and second paper sheets according to the present invention correspond to the first and second paper sheets 11 and 12, respectively. The colorless toner according to the present invention corresponds to the white toner.

[0020] The pressure-sensitive adhesive sheet of this embodiment is a double-folded pressure-sensitive adhesive postcard 1. As shown in FIGS. 1 and 2, the pressure-sensitive adhesive postcard 1 includes a first paper piece 11 and a second paper piece 12, each of which is the size of a regular postcard, joined to the left and right via a bent portion 13. The paper pieces 11 and 12 are folded back at the bent portion 13 and releasably adhered together with adhesive. The pressure-sensitive adhesive postcard 1 is made of a plain white paper substrate 5. The material of the paper substrate 5 is not particularly limited, and it may be a single sheet or a laminated sheet. The pressure-sensitive adhesive postcard 1 is a typical direct mail product, and various information is printed on the outer surface 16 (the surface that faces inward when folded back) and the inside surface 17 (the surface that faces inward when folded back) of the paper substrate 5. As shown in FIG. 1, the printed information on the inside surface 17 is almost invisible when the paper pieces 11 and 12 are in a pressure-sensitive state. However, as shown in FIG. 2, it becomes visible when the paper pieces 11 and 12 are peeled back and opened.

[0021] The first piece of paper 11 and the second piece of paper 12 are crimped over the entire area where they overlap in a folded state. As shown in Figure 2(A), the second piece of paper 12 is slightly narrower in width than the first piece of paper 11, so the entire middle surface 17 of the second piece of paper 12 forms a crimped surface portion 22 that is crimped to the first piece of paper 11. On the other hand, the middle surface 17 of the first piece of paper 11 has an end opposite to the bent portion 13 that forms a non-crimped surface portion 23 that is not crimped to the second piece of paper 12, and the remaining portion forms a crimped surface portion 21 that is crimped to the second piece of paper 12.

[0022] As shown in FIG. 2A, the pressure-bonding surfaces 21 and 22 are composed of an image-forming region 30 on which a color image is printed and a non-image-forming region 31 on which no color image is printed and which exhibits the background color (white) of the paper substrate 5. The color image is formed using one or a combination of cyan (C), magenta (M), yellow (Y), and black (K) color toners. While the color image in FIG. 2A is monotone, an actual color image is a color image. Color images include not only characters and figures but also all images formed with color toners, such as frames and backgrounds, and include both solid and halftone images. Specifically, in FIG. 2B, the black portions of the pressure-bonding surfaces 21 and 22 correspond to the image-forming region 30, and the white portions of the pressure-bonding surfaces 21 and 22 correspond to the non-image-forming region 31.

[0023] A white toner is fixed to the non-image forming areas 31 of the pressure-bonding surfaces 21 and 22 to form a white mesh pattern. A white toner that can be fixed to the pressure-bonding surfaces 21 and 22 by electrophotography at the same time as the color toners that form the color images is preferably used. This white mesh pattern is formed over the entire non-image forming areas 31, but is not formed in the image forming areas 30. Since this mesh pattern is the same white as the background color of the paper substrate 5 and is difficult to see, it is not shown in the drawings. In this embodiment, by forming this difficult-to-see mesh pattern, variations in the adhesive strength of the pressure-bonding surfaces 21 and 22 are reduced without changing the appearance of the pressure-bonding surfaces 21 and 22. The line count and density of this mesh pattern are not particularly limited, but a density of approximately 10 to 50% is desirable.

[0024] The pressure-bonded surfaces 21, 22 of each paper piece 11, 12 are removably bonded with a colorless, transparent adhesive. The adhesive is primarily composed of a pressure-responsive resin that softens under pressure to exert adhesive strength. Once the paper pieces 11, 12 are peeled off, they are difficult to reattach. As described below, the adhesive used is one that can be fixed in powder form to the pressure-bonded surfaces 21, 22 simultaneously with colored and white toners using an electrophotographic method. Examples of such adhesives include well-known adhesives primarily composed of styrene resins and acrylic ester resins. The adhesive is distributed approximately uniformly over the entire pressure-bonded surfaces 21, 22. However, a tear-open portion 15 (see FIG. 1(B)) at one corner of the pressure-bonded surfaces 21, 22 has less adhesive than other portions to facilitate peeling of the paper pieces 11, 12 when opening the package.

[0025] 3A and 3B show the cross-sectional structures of the bonding surfaces 21 and 22 in the bonded state and the unsealed state. A color toner layer 35, formed by fixing color toners, is formed in the image forming area 30 of the bonding surfaces 21 and 22, and a white toner layer 37, formed by fixing white toner, is formed in the non-image forming area 31 of the bonding surfaces 21 and 22. As shown in FIG. 3A, in the bonded state, the first piece 11 and the second piece 12 are bonded via an adhesive layer 39 disposed between the bonding surfaces 21 and 22. As shown in FIG. 3B, in the unsealed state, the first piece 11 and the second piece 12 are peeled off at the interface or between the layers of the adhesive layer 39. While the white toner layer 37 is illustrated as a homogeneous layer in FIG. 3 for convenience, the white toner layer 37 is a flat screen pattern, as described above. Also, for convenience, the color toner layer 35 is illustrated as being a homogeneous layer, but in reality, the color toner layer 35 is composed of one to four layers of four color toners depending on the print content of the color image, and also includes a mixture of areas formed as solids and areas formed as halftone dots.

[0026] Thus, in this embodiment, by fixing toner not only in the image-forming area 30 but also in the non-image-forming area 31, the variation in adhesive strength on the pressure-bonding surfaces 21 and 22 can be reduced compared to conventional configurations. In particular, with this configuration, by appropriately fixing white toner to the non-image-forming area 31, the variation in adhesive strength can be significantly reduced compared to adjusting the amount of adhesive. While the non-image-forming area 31 becomes relatively difficult to adhere due to the fixing of white toner, the overall adhesive strength of the pressure-bonding surfaces 21 and 22 can be adjusted by adjusting the pressure and other pressing conditions. Therefore, by reducing the variation in adhesive strength on the pressure-bonding surfaces 21 and 22, areas with excessive or insufficient adhesive strength can be reduced by pressing the pieces of paper 11 and 12 together under appropriate pressing conditions. Therefore, the pressure-bonded postcard 1 of this embodiment has the advantage of being less susceptible to localized peeling on the pressure-bonding surfaces 21 and 22 and damage when opened compared to conventional configurations.

[0027] Furthermore, in the pressure-bonded postcard 1 of this embodiment, toner is fixed to both the image-forming area 30 and the non-image-forming area 31, so even if the area ratio of the color image (image-forming area 30) changes, the adhesive strength of the pieces of paper 11, 12 does not fluctuate significantly. Therefore, in this embodiment, the effort required to adjust the pressure-bonding conditions depending on the amount of color image can be reduced compared to conventional configurations.

[0028] The above-mentioned pressure-bonded postcard 1 can be produced, for example, by a production method including the following steps (1) to (5). (1) Cutting of the paper substrate 5 (2) Printing on the middle surface 17 of the paper substrate 5 and laminating the adhesive (3) Printing on the outer surface 16 of the paper substrate 5 (4) Folding the paper substrate 5 (5) Pressing the first paper piece 11 and the second paper piece 12 together Here, the above step (2) corresponds to the first step according to the present invention, and the above steps (4) and (5) correspond to the second step according to the present invention.

[0029] In the above step (1), the paper substrate 5 is cut to the size of the pressure-sensitive adhesive postcard 1, similar to the existing method of manufacturing pressure-sensitive adhesive postcards. In the above step (2), a color image using color toners and a grid pattern using white toner are printed on the pressure-sensitive adhesive surfaces 21 and 22 by electrophotography, and at the same time, an adhesive is layered on top of the toner on the pressure-sensitive adhesive surfaces 21 and 22. Details of these steps will be described later. The order of the above steps (2) and (3) can be reversed, and they can be performed consecutively using the double-sided printing function of the image forming device 40, which will be described later.

[0030] In step (4) above, the paper base material 5 is folded back at the boundary (bend 13) between the first sheet 11 and the second sheet 12, either manually or using a folding machine, as with conventional pressure-bonded postcards. In step (5) above, the sheets 11 and 12 are pressed together while being heated by the rollers of the pressure-bonding machine, as with conventional pressure-bonded postcards. This causes the pressure-responsive resin of the adhesive applied to the pressure-bonding surfaces 21 and 22 to soften and generate adhesive force, bonding the pressure-bonding surfaces 21 and 22 together. Note that the color toner layer 35 and the white toner layer 37 formed on the pressure-bonding surfaces 21 and 22 do not contain pressure-responsive resin, and therefore do not soften or generate adhesive force even when pressed by the pressure-bonding machine.

[0031] In the above step (5), the pressure-bonding conditions (pressure force, pressure time, etc.) are adjusted so that the adhesive strength of the entire pressure-bonded surfaces 21, 22 is within an appropriate range. As described above, in the pressure-bonded postcard 1 of this embodiment, the adhesive strength of the paper pieces 11, 12 does not fluctuate significantly even if the area ratio of the colored image varies, so even in a manufacturing site where the colored image of the pressure-bonded postcard 1 is frequently changed, the effort of adjusting the pressure-bonding conditions can be minimized.

[0032] 4 is a schematic diagram of an image forming apparatus 40 used in the above step (2). The image forming apparatus 40 is an intermediate transfer type color laser printer. The image forming apparatus 40 includes six image forming units 41a to 41d, 42, and 43, an intermediate transfer belt 45, a transfer unit 46 that transfers the image carried by the intermediate transfer belt 45 onto a paper substrate 5, and a fixing unit 47 that heats and fixes the image transferred onto the paper substrate 5.

[0033] The image forming units 41a to 41d, 42, and 43 each form an image by performing electrophotographic charging, exposure, and development processes. As shown in FIG. 4, the image forming apparatus 40 is of a tandem type, and the six image forming units 41a to 41d, 42, and 43 are arranged side by side along the direction of travel of the intermediate transfer belt 45. That is, the images formed by the image forming units 41a to 41d, 42, and 43 are transferred in order from their respective photosensitive elements to the intermediate transfer belt 45 (primary transfer). Then, after all the images are carried on the intermediate transfer belt 45, they are all transferred together from the intermediate transfer belt 45 to the paper substrate 5 (secondary transfer).

[0034] Each of the four image forming units 41a to 41d is fitted with a cartridge filled with cyan, magenta, yellow, and black color toner. That is, color toner images are formed by these image forming units 41a to 41d. Furthermore, a cartridge filled with white toner is fitted to one image forming unit 42. That is, a halftone dot toner image is formed by this image forming unit 42. And the remaining image forming unit 43 is filled with a powder adhesive capable of fixing an image by electrophotography. That is, an adhesive image is formed by this image forming unit 43.

[0035] Thus, in the step (2) above, the image forming apparatus 40 uses electrophotography to layer a color toner image (color image), a white toner image (halftone dot image), and an adhesive image on the intermediate transfer belt 25, and then fixes them together on the paper substrate 5. Because the image forming apparatus 40 supports variable printing, it is suitable for manufacturing sites where the color images formed on the pressure-bonding surfaces 21 and 22 are frequently changed. Note that, as shown in FIG. 4, if the adhesive image forming unit 43 is located at the most upstream side in the traveling direction of the intermediate transfer belt 45, the adhesive image is fixed to the paper substrate 5 in a state where it is layered on top of the color toner and white toner images.

[0036] The image forming apparatus 40 described above is well known, and the color toner, white toner, and adhesive powder used may be well known and compatible with the well-known image forming apparatus 40, so detailed description will be omitted. A specific example of the image forming apparatus 40 is the Revorias Press PC1120 (manufactured by Fujifilm Business Innovation Co., Ltd.).

[0037] <Test item> In order to evaluate the above-mentioned pressure-sealed postcard 1, the following test products were produced according to the above-mentioned manufacturing method. The paper substrate 5 used was a common white coated paper (Utleyro Gloss Matte Natural, manufactured by Daio Paper Corporation: basis weight 110 kg, paper thickness approximately 138 μm), which was cut to the size of the above example.

[0038] Revorias Press PC1120 was used to print the colored images and dotted lines on the inside surface 17, and to laminate the adhesive. The colored toner, white toner, and powder adhesive (pressure-bonded toner) used were specially designed for Revorias Press PC1120. The components of each toner and powder adhesive are outlined below. Color toner: polyester resin, ferrite, wax, pigment, silica White toner: polyester resin, white pigment, ferrite, wax, silica Powder adhesive: pressure-responsive resin (styrene / acrylic resin), ferrite, silica

[0039] Two types of test samples were prepared: one with a high color image printing area ratio (area ratio 74%) and one with a low color image printing area ratio (area ratio 16%).

[0040] The white toner halftone dots were formed over the entire non-image forming area 31. Three types of test samples with densities of 10%, 25%, and 50% were prepared for the white toner halftone dots.

[0041] The powder adhesive was applied to the entire pressure-bonding surfaces 21 and 22 in a flat mesh pattern with a density of 40%.

[0042] A crimping machine (HP-L model heat crimping machine manufactured by Hamamatsu Corporation) was used to crimp the crimped postcards 1. The crimping machine uses a heated crimping roller to roll press the paper substrate 5 to crimp it, and crimping was performed under the following crimping conditions. The gap between the crimping rollers was varied in the range of 0.05 mm to 0.15 mm to create several test samples with different pressure forces during crimping. Pressure roller temperature: 55℃ Pressure roller feed speed: 25m / min Pressure roller gap: 0.05mm~0.15mm

[0043] <Comparative product> A plurality of comparative products were prepared in the same manner as the test product except that no tint was formed with white toner in the non-image forming areas 31 .

[0044] <Evaluation test> The test and comparative samples of the press-bonded postcards 1 were manually opened to evaluate the degree of adhesion of the press-bonded surfaces 21 and 22. The results are shown in Figure 5. As shown in Figure 5, the test samples with a 10% mesh pattern were properly bonded when the pressure roller gap was set to 0.1 mm, regardless of whether the color image area ratio was high (74%) or low (16%). The test samples with a 25% mesh pattern were properly bonded when the pressure roller gap was set to 0.05 to 0.1 mm, regardless of whether the color image area ratio was high or low. The test samples with a 50% mesh pattern were properly bonded when the pressure roller gap was set to 0.05 mm, regardless of whether the color image area ratio was high or low. These results indicate that even when a mesh pattern is formed with white toner in the non-image-forming region 31, as in the test sample, the press-bonded surfaces 21 and 22 can be bonded with appropriate adhesive strength by adjusting the pressure (press roller gap) during compression.

[0045] On the other hand, for the comparison products with a high color image area ratio, the product was properly pressed when the pressure roller gap was set to 0.05 mm to 0.1 mm, but for the comparison products with a low color image area ratio, the adhesive strength was too strong to peel under the same pressing conditions (gap of 0.05 mm to 0.1 mm), and the product was properly pressed when the gap was set to 0.15 mm. This result shows that for the comparison products in which toner is not fixed in the non-image forming areas 31, the pressure during pressing (gap of the pressure roller) needs to be changed more frequently depending on the effective image area ratio than for the test products.

[0046] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0047] For example, the above embodiment is a double-folded press-bonded postcard 1, but the press-bonded sheet of the present invention can also be applied to a triple-folded or quarter-folded press-bonded postcard, and can also be applied to printed materials other than press-bonded postcards. Furthermore, the two pieces of paper 11, 12 that are pressed together do not have to be joined together on a single sheet, but may be discontinuous.

[0048] In the above embodiment, the entire overlapping area of ​​the paper pieces 11, 12 is the pressure-bonding surface portions 21, 22, but only a portion of the overlapping area of ​​the paper pieces 11, 12 may be the pressure-bonding surface portions 21, 22.

[0049] Furthermore, in the above embodiment, adhesive is distributed approximately uniformly over the entire area of ​​the pressure-bonding surface portions 21 and 22, but the invention described in the above Patent Document 1 may be applied to the above embodiment, and the amount of adhesive may be varied between the image forming area 30 and the non-image forming area 31, or the amount of adhesive distributed in the image forming area 30 may be varied depending on the amount of color toner adhered.

[0050] In addition, in the above embodiment, a flat mesh of white toner is provided in the non-image forming area 31 of each of the pressure-bonded surface portions 21, 22 of the first paper sheet 11 and the second paper sheet 12, but the present invention also includes a configuration in which a flat mesh of white toner is formed only in the non-image forming area 31 of the pressure-bonded surface portions 21, 22 on one side.

[0051] Furthermore, in the above embodiment, a white toner dot pattern is formed in the non-image forming area 31, but the colorless pattern according to the present invention is not limited to a dot pattern and may be a regular pattern such as lines. Furthermore, the colorless pattern according to the present invention may be any color that does not affect the paper color of the pieces of paper 11, 12. Furthermore, the colorless toner according to the present invention is not limited to white toner and may be a colorless, transparent toner. Furthermore, in the above embodiment, a white toner dot pattern is formed over the entire non-image forming area 31, but the white toner dot pattern may be removed in some areas of the non-image forming area 31. [Explanation of symbols]

[0052] 1. Pressure-sealed postcard (pressed sheet) 5 Paper base material 11 First Piece of Paper (First Piece of Paper) 12 Second Piece of Paper (Second Piece of Paper) 13 Bend 15 Opening section 16 Exterior 17 Inside 21, 22 Crimping surface 23 Non-crimped surface 30 Image formation area (color image formation area) 31 Non-image forming area (area where no color image is formed) 35 Color toner layer 37 White toner layer 39 Adhesive layer 40 Image forming device 41a to 41d color toner image forming units 42 Colorless toner image forming unit 43 Adhesive layer forming section 45 Intermediate transfer belt 46 Transfer section 47 Fixing section

Claims

1. A pressure-bonded sheet in which a second piece of paper is releasably bonded to a pressure-bonded surface of a first piece of paper via an adhesive, A pressure-sensitive adhesive sheet characterized in that a colored image is formed on the pressure-sensitive adhesive surface by fixing a colored toner, and a regular colorless pattern is formed in the areas where the colored image is not formed by fixing a colorless toner that does not affect the paper color of the first piece of paper.

2. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the colorless pattern is a flat mesh.

3. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the colorless pattern is not formed in a region where the colored image is to be formed.

4. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the colorless pattern is formed in substantially the entire area of ​​the area where the colored image is not formed.

5. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the colorless pattern is formed in a region where the colored image is not formed, with a printing rate of 10 to 50%.

6. A method for manufacturing a pressure-bonded sheet in which a second piece of paper is releasably bonded to a pressure-bonded surface of a first piece of paper via an adhesive, comprising: a first step of fixing toner on the pressure-bonding surface by an electrophotographic method and laminating an adhesive on the toner; a second step of overlapping and pressing the second piece of paper onto the pressing surface; Including, A method for manufacturing a pressure-bonded sheet, characterized in that in the first step, a colored image is formed on the pressure-bonded surface using a colored toner, and a regular colorless pattern is formed in the areas where the colored image is not formed using a colorless toner that does not affect the paper color of the first piece of paper.

Images