Sheet decoration method

Abstract

To provide a sheet decoration method capable of decorating a sheet at low cost.SOLUTION: A sheet decoration method includes: a coating step of coating a varnish having ultraviolet curability, onto a first area A1 on the surface of a sheet, and a second area A2 having ultraviolet reflectance lower than that of the first area A1; a curing step of irradiating the varnish coated onto the first area A1 and the second area A2 with ultraviolet light, curing the varnish coated onto the first area A1, and semi-curing the varnish coated onto the second area A2; and a transfer step of executing predetermined transfer processing to the semi-cured varnish.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a sheet decoration method. [Background technology]

[0002] There is known a technique for transferring a transfer material such as a foil onto a varnish applied to the surface of a sheet, and also a technique for closely adhering a transfer web to the varnish applied to the surface of a sheet to transfer the surface shape of the transfer web to the varnish. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-167109 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, when mixing a varnished area on the surface of a sheet, which is only coated with varnish, and a transfer area where a transfer process such as foil stamping has been performed on the varnish, the sheet had to be passed through the machine for coating and again for the transfer process, meaning that the sheet had to be passed through the machine twice.

[0005] The present invention has been made in this situation, and one exemplary objective of one of its aspects is to provide a sheet decoration method that can decorate a sheet having a mixture of varnish-coated areas and transfer areas by passing the sheet through the machine just once. [Means for solving the problem]

[0006] In order to solve the above problems, a sheet decoration method of one embodiment of the present invention includes an application step of applying an ultraviolet-curable varnish to a first area on the surface of a sheet and to a second area having a lower ultraviolet reflectance than the first area, a curing step of irradiating the varnish applied to the first and second areas with ultraviolet light to harden the varnish applied to the first area and semi-harden the varnish applied to the second area, and a transfer step of performing a predetermined transfer process on the semi-hardened varnish.

[0007] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0008] According to the present invention, it is possible to provide a sheet decoration method capable of decorating a sheet having a mixture of varnished areas and transferred areas by passing the sheet through the machine only once. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic diagram of a sheet decoration system according to an embodiment. [Diagram 2] 1 is a top view showing a schematic diagram of a sheet decoration system according to an embodiment. FIG. [Diagram 3] 3(a) and (b) show the semi-cured varnish layer. [Figure 4] 4(a) and (b) are plan views of the sheet. [Diagram 5] FIG. 13 is a diagram summarizing the experimental results. [Figure 6] FIG. 13 is a diagram summarizing the experimental results. [Figure 7] FIG. 13 is a diagram summarizing the experimental results. [Figure 8] FIG. 13 is a diagram summarizing the experimental results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, parts, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, in the present invention, the base or base image refers to a sheet surface on which an image has already been formed as necessary immediately before passing the sheet through the sheet decoration system of the present invention, or an image formed on the sheet surface. The underlayer color refers to the color of the sheet surface on which the base image is to be printed.

[0011] 1 and 2 are diagrams showing a schematic diagram of a sheet decoration system 10. FIG. 1 is a side view, and FIG. 2 is a plan view. The sheet decoration system 10 is a system that applies a predetermined decoration to a sheet while transporting the sheet. The material of the sheet varies, including paper, cloth, resin, and metal. Hereinafter, the direction in which the sheet is transported (direction from right to left in FIGS. 1 and 2) is called the transport direction Y, and the direction perpendicular to the transport direction Y (direction perpendicular to the paper surface in FIG. 1 and the up-down direction in FIG. 2) is called the width direction X. The downstream edge of the sheet in the transport direction Y is called the leading edge of the sheet, and the upstream edge is called the trailing edge of the sheet.

[0012] The sheet decoration system 10 includes a printing device 12 that prints on sheets and feeds the sheets one by one, a varnishing device 14 that applies ultraviolet-curable varnish (hereinafter, simply referred to as "varnish") to the sheets fed one by one, a foil stamping device 16 that transfers foil to the varnish applied to the sheet by utilizing the tackiness of the varnish, i.e., foil stamping, a stacker 18 that accumulates the sheets, and a control device 20 that performs overall control of the sheet decoration system 10. The printing device 12, the varnishing device 14, the foil stamping device 16, and the stacker 18 are arranged in a line in this order from the upstream side (the right side in Figs. 1 and 2) to the downstream side in the conveying direction Y. The control device 20 is connected to the printing device 12, the varnishing device 14, the foil stamping device 16, and the stacker 18 via a network 2.

[0013] The printing device 12 prints a base image and a plurality of registration marks that are references for identifying the position of the base image. The printing device 12 feeds the printed sheets one by one to the varnish applying device 14.

[0014] The varnish application device 14 includes a sheet sensor 42, at least one varnish discharge section 46 (three in FIG. 2), and an ultraviolet lamp 48. The sheet sensor 42, the varnish discharge section 46, and the ultraviolet lamp 48 are provided in this order from the upstream side to the downstream side. The number of varnish discharge sections 46 is not particularly limited. The varnish application device 14 may include one varnish discharge section 46 extending over the range of the width direction X in which varnish discharge is required or more, or may include two or four or more varnish discharge sections 46. The ultraviolet lamp 48 uses an LED that emits ultraviolet light, but other light sources such as light bulbs and fluorescent lamps that emit ultraviolet light may also be used. It is preferable that the light source has adjustable output.

[0015] The sheet sensor 42 detects a sheet fed from the printing device 12 .

[0016] The varnish ejection unit 46 is a line-type inkjet head, although there is no particular limitation. The varnish ejection unit 46 ejects varnish according to the varnish ejection data when triggered by the detection of the leading edge of the sheet by the sheet sensor 42, and applies the varnish to the sheet. The varnish ejection data is data indicating the area on the sheet to which the varnish is to be applied. The areas to which the varnish is to be applied are a first area and a second area, which will be described later. In other words, when the sheet is passed through the varnish application device 14 once, the varnish is applied to the first area and the second area on the surface of the sheet.

[0017] The ultraviolet lamp 48 irradiates the varnish applied to the sheet with ultraviolet light to fully cure or semi-cure the varnish. Full curing refers to completely curing the varnish. Semi-curing refers to curing the varnish lightly enough to reduce its fluidity but not completely cure it, for example, to a state where it can be further cured. The semi-cured varnish is foil stamped in the foil stamping device 16 and then fully cured. In other words, the ultraviolet lamp 48 fully cures the varnish applied to the area on the surface of the sheet that is only coated with varnish and not foil stamped (hereinafter referred to as the "first area"), and semi-cures the varnish applied to the area on the surface of the sheet that is subsequently foil stamped in the foil stamping device 16 (hereinafter referred to as the "second area").

[0018] FIG. 3 is a diagram showing a varnish layer 100 that has been applied onto a sheet S by a varnish discharge unit 46 and semi-cured by an ultraviolet lamp 48. The semi-cured varnish layer 100 includes a cured portion 100a and an uncured portion 100b that has not been sufficiently cured. The cured portion 100a occupies the interior of the varnish layer 100, while the uncured portion 100b occupies the surface portion of the varnish layer 100. This is because the surface portion that is exposed to the outside air is more difficult to cure due to the effects of oxygen inhibition. The surface portion of the varnish layer 100 does not have fluidity, but is not completely cured and has a tacky state.

[0019] The semi-cured varnish is irradiated with ultraviolet light again in the final curing ultraviolet lamp 50 or foil stamping device 16, and is fully cured. Full curing refers to all parts of the varnish layer 100 being completely cured. Since the cured parts 100a, 102a account for most of the part of the semi-cured varnish layer 100 that is adhered to the sheet S, the adhesive part is stabilized. Therefore, until the final curing, the varnish layer 100 can be prevented from seeping onto the sheet S and spreading in the sheet surface direction (direction of arrow A), and the shape of the sheet S in the surface direction is stabilized.

[0020] The foil stamping device 16 conveys the sheet and also conveys the web (transfer web) 52 in a roll-to-roll manner, and transfers, i.e., foil stamps, the foil held by the web 52 onto the sheet by utilizing the tackiness of the semi-cured varnish. The web 52 is a foil-holding film in which a foil (e.g., a metal foil) is held on a film (base sheet). The foil stamping device 16 adheres the foil held by the web 52 to the varnish by utilizing the tackiness of the semi-cured varnish. With the foil adhered to the semi-cured varnish and held by the web 52, the semi-cured varnish is irradiated with ultraviolet light by the foil stamping ultraviolet lamp 66 to fully harden the varnish. When the varnish is fully hardened, the force with which the foil adheres to the varnish becomes stronger than the force with which the web 52 holds the foil. In this state, when the web 52 is separated from the sheet, the foil held by the web 52 is transferred to the varnish.

[0021] The stacker 18 accumulates the sheets (decorative sheets) discharged from the foil stamping device 16.

[0022] The control device 20 is, for example, an information processing terminal such as a PC. The control device 20 accepts input regarding a definition of a print job. The control device 20 may display a predetermined job management screen and accept input of a job definition. The job definition includes, for example, the number of sheets to be decorated (number of decorated copies), the sheet size of the sheets to be decorated, varnish data, and whether or not to perform foil stamping. The control device 20 controls the printing device 12, the varnish application device 14, and the foil stamping device 16 based on the job definition.

[0023] The above is the basic configuration of the sheet decoration system 10.

[0024] Alternatively, the printing device 12 may be located at a location physically separate from the varnishing device 14, the foil stamping device 16 and the stacker 18. In this case, the sheet decoration system 10 may further comprise a paper feeder that feeds the sheets printed by the printing device 12 to the varnishing device 14 one by one.

[0025] The sheet decoration system 10 may also include other devices between the hot foil stamping device 16 and the stacker 18. The other devices may be, for example, a post-processing device for cutting or stapling the sheets, a separate coating device for protecting the foil surface with varnish, a slip sheet inserter for surface protection, a punching machine for punching the sheets into a predetermined shape to create carton materials or the like, or a post-processing machine for surface protection of slip sheets or the like.

[0026] The inventor recognized that with a varnish application device, not only the direct ultraviolet light emitted from the ultraviolet lamp, but also the reflected ultraviolet light from the base contributes to the hardening of the varnish, and therefore, even if ultraviolet light is irradiated onto the varnish under the same irradiation conditions, the higher the ultraviolet reflectivity of the base, the more rapidly the varnish will harden.

[0027] Based on this recognition, the inventors have conceived the idea that, by utilizing the difference in UV reflectance of the base, it is possible to fully cure the varnish applied to a first area on the surface of the sheet and semi-cure the varnish applied to a second area by simply passing the sheet once through the varnishing device 14, i.e., it is possible to coat the first area on the surface of the sheet with varnish and foil stamp the second area by simply passing the sheet once through the sheet decoration system 10.

[0028] Therefore, in the sheet decoration system 10, the UV reflectance of the second region is made lower than that of the first region by printing at least one of the first region and the second region in the printing device 12. Note that when the base is opaque, "high UV reflectance" and "low UV reflectance" can be rephrased as "low UV absorbance" and "high UV absorbance", respectively.

[0029] Figures 4(a) and (b) are plan views of a sheet S. Figure 4(a) shows the sheet S before printing, and Figure 4(b) shows the sheet S after printing. Printing of the first area A1 and the second area A2 in the printing device 12 will be described with reference to Figures 4(a) and (b).

[0030] The printing device 12 may print both the first region A1 and the second region A2 as shown in FIG. 4(b). The printing device 12 may print the first region A1 in a first color and the second region A2 in a second color. In this case, the second color may be a color with a lower ultraviolet reflectance than the first color, in other words, a color with a longer wavelength. The first region A1 may be printed only partially, and the second region A2 may be printed entirely. In this case, the second color may be a color with a lower ultraviolet reflectance than the first color and the color of the sheet S, in other words, a color with a longer wavelength. The first region A1 may be printed entirely, and the second region A2 may be printed only partially. In this case, the first color may be a color with a higher ultraviolet reflectance than the second color and the color of the sheet S, in other words, a color with a shorter wavelength. However, since the second region A2 is stamped, the color of the base of the second region A2 is not visible.

[0031] Unlike FIG. 4(b), the printing device 12 may print the first area A1 in a first color and not print the second area A2. In other words, the printing device may print only the first area A1. In this case, the original (i.e., unprinted) color of the surface of the sheet S (hereinafter simply referred to as the "color of the sheet S") is the color of the second area A2 when the varnish is applied. Therefore, the first color may be a color with a higher ultraviolet reflectance than the color of the sheet S, in other words, a color with a shorter wavelength than the color of the sheet S. For example, the color of the sheet S may be black.

[0032] Unlike FIG. 4(b), the printing device 12 may print the second area A2 in the second color and not print the first area A1. In other words, the printing device may print only the second area A2. In this case, the color of the sheet S is the color of the first area A1 when the varnish is applied. Therefore, the second color may be a color with a lower ultraviolet reflectance than the color of the sheet S, in other words, a color with a longer wavelength. For example, the color of the sheet S may be white.

[0033] In the above explanation, for simplicity, the first area A1 is printed in one color, i.e., the first color, but the first area A1 may be printed in two or more colors. For example, the colors of two first areas A1 that are separated from each other may be different. For example, the colors of "0" and "1" in "sample01" may be different from each other. Also, for example, one first area A1 may be printed in two colors. For example, "0" in "sample01" may be printed in two colors.

[0034] Similarly, in the above description, for simplicity, the second area A2 is printed in one color, i.e., the second color, but the second area A2 may be printed in two or more colors. However, because the second area A2 is foil stamped, the base of the second area A2 becomes invisible.

[0035] In any case, by printing at least one of the first region A1 and the second region A2 in the printing device 12, the ultraviolet reflectance of the second region A2 is made lower than the ultraviolet reflectance of the first region A1.

[0036] The greater the difference between the ultraviolet reflectance of the first region A1 and the ultraviolet reflectance of the second region A2, the more preferable. If the difference is large, the first region A1 can be fully cured more reliably when the second region A2 is irradiated with ultraviolet light under irradiation conditions that semi-cure the second region A2. In this embodiment, the second region A2 is foil stamped, so from the viewpoint of design, the second region A2 can be any color. Therefore, when printing the second region A2, regardless of whether the first region A1 is printed or not and the color in which the first region A1 is printed, the second region A2 can be printed in a color with a lower ultraviolet reflectance. For example, the entire second region A2 can be printed in black. In this case, the difference between the ultraviolet reflectance of the first region A1 and the ultraviolet reflectance of the second region A2 can be made larger than when the second region A2 is printed in another color.

[0037] On the other hand, even if the UV reflectance (R1) of the first region A1 and the UV reflectance (R2) of the second region A2 satisfy the relationship R1>R2, if the difference between them is small, no matter how the irradiation conditions are adjusted, it is not possible to fully cure the first region A1 and semi-cure the second region A2. In other words, if the difference between R1 and R2 is small, no matter how the irradiation conditions are adjusted, when attempting to fully cure the first region A1, the second region A2 will also be fully cured. Therefore, in order to fully cure the first region A1 and semi-cure the second region A2, the relationship of the following formula 1 must be satisfied. R1-R2≧R th ...(Formula 1)

[0038] R th is a threshold value. The ultraviolet ray reflectance (R1) of the first region A1 is preferably 70% or more, and more preferably 80% or more. The ultraviolet ray reflectance (R2) of the second region A2 is preferably 30% or less, and more preferably 20% or less. Therefore, the threshold value R th is preferably 40% or more, and more preferably 60% or more. th This can be determined based on findings obtained through experiments as to whether it is possible to fully cure the first region A1 and semi-cure the second region A2 by adjusting the irradiation conditions.

[0039] When the first region A1 includes multiple colors, the UV reflectance of the color with the lowest UV reflectance can be used for R1 in formula 1. When the second region A2 includes multiple colors, the UV reflectance of the color with the lowest UV reflectance can be used for R2 in formula 1.

[0040] In the case where the printing device 12 is a printing device that is premised on printing the white color as an underlayer color on a white sheet S or a sheet S on which a solid white print has been applied, and is a printing device that expresses white by not printing, if the proportion of the white color remaining as the underlayer color in the first region A1 and the second region A2 is high, the ultraviolet reflectance will be relatively high, and if the proportion of the white color remaining as the underlayer color is low, the ultraviolet reflectance will be relatively low. Therefore, the formula 1 can be rewritten as the following formula 2 using the proportion (W1) of the underlayer color (i.e., white) remaining in the first region A1 and the proportion (W2) of the area in the second region A2 where the underlayer color (i.e., white) remains. It should be noted that "white" here includes not only completely white, but also approximately white, which can be considered to be substantially white in terms of technical common sense. W1-W2≧W th ...(Formula 2)

[0041] W th is the threshold. Threshold W th is at least 30%, preferably 40% or more, and more preferably 50% or more. th This can be determined based on findings obtained through experiments as to whether it is possible to fully cure the first region A1 and semi-cure the second region A2 by adjusting the irradiation conditions.

[0042] Furthermore, if the printing device 12 is a halftone printing device that performs halftone printing, if the dot area ratios printed in the first area A1 and the second area A2 are low, it can be said that the percentage of the white of the underlying color remaining is high, and if the dot area ratios are high, it can be said that the percentage of the white of the underlying color remaining is low. In other words, if the dot area ratios printed in the first area A1 and the second area A2 are low, the ultraviolet reflectance is relatively high, and if the dot area ratios are high, the ultraviolet reflectance is relatively low. Therefore, Equation 2 can be rewritten using the dot area ratios. Here, assuming that the printing device 12 is a halftone printing device that performs halftone printing using four inks of CMYK, Equation 2 is rewritten as Equation 3 below using the dot area ratios (C1, M1, Y1, K1) of cyan, magenta, yellow, and black printed in the first area A1 and the dot area ratios (C2, M2, Y2, K2) of cyan, magenta, yellow, and black printed in the second area A2. Each dot percentage is obtained from the printing device 12. (Formula 3){100-(k c ×C1+k m ×M1+k y ×Y1+k k ×K1)}-{100-(k c ×C2+k m ×M2+k y ×Y2+k k ×K2)}≧S th

[0043] S th is the threshold. Threshold S th is at least 30%, preferably 40% or more, and more preferably 50% or more. th This can be determined based on findings obtained through experiments as to whether it is possible to fully cure the first region A1 and semi-cure the second region A2 by adjusting the irradiation conditions.

[0044] Also, k c ,k m ,k y ,k kare coefficients corresponding to the colors cyan, magenta, yellow, and black. Since cyan, magenta, yellow, and black have different reflectances, the influence of the dot area ratios of cyan, magenta, yellow, and black on the ultraviolet reflectance of the first area A1 and the second area A2 is different. c ,k m ,k y ,k k is a coefficient for compensating for the difference in the effect. For example, the coefficient k for black, which has a low reflectance, k The other color coefficients k c ,k m ,k y is set to a value smaller than

[0045] Even if the underlayer color is not white, if it is a color with high UV reflectance, in other words a color with a short wavelength, then if the proportion of the underlayer color remaining in the first region A1 and the second region A2 is high, the UV reflectance will be relatively high, and if the proportion of the underlayer color remaining is low, the UV reflectance will be relatively low. Therefore, even if the underlayer color is not white, if it is a color with high UV reflectance, Equation 2 and Equation 3 can be established. In this case, in Equation 2, the threshold value W th may differ from when the underlayer color is white, but may be determined based on findings obtained by conducting experiments similar to the case when the underlayer color is white. th and coefficient k c ,k m ,k y ,k k may differ from when the underlayer color is white, but may be determined based on findings obtained through experiments similar to those in the case where the underlayer color is white.

[0046] Next, the ultraviolet irradiation conditions in the varnish application device 14 will be described. The ultraviolet irradiation conditions are the cumulative amount of ultraviolet light (J / cm 2 The ultraviolet irradiation conditions include at least the ultraviolet irradiation intensity, the ultraviolet irradiation distance, and the sheet conveying speed.

[0047] "Ultraviolet irradiation intensity" is the ultraviolet intensity of the ultraviolet light irradiated by the ultraviolet lamp 48. The higher the ultraviolet irradiation intensity, the higher the ultraviolet intensity of the ultraviolet light irradiated to the varnish, and therefore the greater the cumulative amount of ultraviolet light irradiated to the varnish. The lower the ultraviolet irradiation intensity, the lower the ultraviolet intensity of the ultraviolet light irradiated to the varnish, and therefore the smaller the cumulative amount of ultraviolet light irradiated to the varnish.

[0048] The "ultraviolet irradiation distance" is the distance from the ultraviolet lamp 48 to the sheet. The shorter the ultraviolet irradiation distance, the higher the ultraviolet intensity of the ultraviolet light irradiated to the varnish, and therefore the greater the cumulative amount of ultraviolet light irradiated to the varnish. The longer the ultraviolet irradiation distance, the lower the ultraviolet intensity of the ultraviolet light irradiated to the varnish, and therefore the smaller the cumulative amount of ultraviolet light irradiated to the varnish.

[0049] The "sheet conveying speed" is the conveying speed at which the sheet is conveyed. The slower the sheet conveying speed, the longer the ultraviolet irradiation time, and therefore the greater the cumulative amount of ultraviolet light irradiated onto the varnish. The faster the sheet conveying speed, the shorter the ultraviolet irradiation time, and therefore the smaller the cumulative amount of ultraviolet light irradiated onto the varnish.

[0050] If the cumulative amount of ultraviolet light irradiated to the varnish is too large, not only the varnish in the first area A1 but also the varnish in the second area A2 may be fully cured. If the cumulative amount of ultraviolet light irradiated to the varnish is too small, the varnish in the first area A1 may not be fully cured, or the varnish in the second area A2 may not be semi-cured. However, even if the cumulative amount of ultraviolet light is relatively large, it may be an appropriate cumulative amount of light depending on the combination of the ultraviolet reflectance of the first area A1 and the ultraviolet reflectance of the second area A2, and conversely, even if the cumulative amount of ultraviolet light is relatively small, it may be an appropriate cumulative amount of light depending on the combination of the ultraviolet reflectance of the first area A1 and the ultraviolet reflectance of the second area A2.

[0051] Therefore, the ultraviolet ray irradiation conditions are determined based on the ultraviolet ray reflectances of the first region A1 and the second region A2. That is, at least one of the ultraviolet ray irradiation conditions is adjusted based on the ultraviolet ray reflectances of the first region A1 and the second region A2.

[0052] Conversely, the ultraviolet reflectance of the first region A1 and the second region A2 may be determined in accordance with the ultraviolet irradiation conditions. In other words, the color to be printed in at least one of the first region A1 and the second region A2 may be determined in accordance with the ultraviolet irradiation conditions.

[0053] In any case, the varnish application device 14 irradiates the varnish applied to the first area A1 and the second area A2 with ultraviolet light under irradiation conditions according to the ultraviolet reflectance of both the first area A1 and the second area A2. In this case, the irradiation conditions may be adjusted automatically. For example, the control device 20 may store irradiation conditions for each of a plurality of combinations of the ultraviolet reflectance of the first area A1 and the second area A2. Alternatively, the control device 20 may store irradiation conditions for each of a plurality of combinations of the colors of the first area A1 and the second area A2.

[0054] Also, to reiterate, if the printing device 12 is a printing device that is premised on printing the white color as an underlayer color on a white sheet S or a sheet S with a solid white print, and is a printing device that expresses the white color by not printing, if the proportion of the white color remaining as the underlayer color in the first region A1 and the second region A2 is high, the ultraviolet reflectance will be relatively high, and if the proportion of the white color remaining as the underlayer color is low, the ultraviolet reflectance will be relatively low. Thus, the irradiation conditions according to the ultraviolet reflectances of both the first region A1 and the second region A2 can also be considered as irradiation conditions according to the proportion of the underlayer color remaining in both the first region A1 and the second region A2.

[0055] In addition, again, when the printing device 12 is a halftone printing device that performs halftone printing, if the dot area rate printed in the first region A1 and the second region A2 is low, it can be said that the ratio of the white color of the underlayer remaining is high, and if the dot area rate is high, it can be said that the ratio of the white color of the underlayer remaining is low. In other words, if the dot area rate printed in the first region A1 and the second region A2 is low, the ultraviolet reflectance is relatively high, and if the dot area rate is high, the ultraviolet reflectance is relatively low. Thus, the irradiation conditions according to the ultraviolet reflectance of both the first region A1 and the second region A2 can also be regarded as irradiation conditions according to the dot area rate of both the first region A1 and the second region A2. In this case, the irradiation conditions may be automatically adjusted. For example, the control device 20 may store irradiation conditions for each of a plurality of combinations of the dot area rates of the first region A1 and the second region A2.

[0056] Similarly, when a color that is not white but has a high UV reflectance is used as an underlayer color and printed on top of it, if the proportion of the underlayer color remaining in the first region A1 and the second region A2 is high (if the dot area ratio is low in the case of a halftone printing device), the UV reflectance will be relatively high, and if the proportion of the underlayer color remaining is low (if the dot area ratio is high in the case of a halftone printing device), the UV reflectance will be relatively low. Therefore, the irradiation conditions according to the UV reflectance of both the first region A1 and the second region A2 can also be considered as irradiation conditions according to the proportion of the underlayer color remaining in both the first region A1 and the second region A2 (the dot area ratio in the case of halftone printing).

[0057] Next, an experiment conducted by the inventor will be described. The inventor prepared a number of sample sheets, applied varnish to the sample sheets, irradiated the varnish with ultraviolet light, and performed foil stamping.

[0058] The undercoat color of the sample sheet is white, and the sample sheet is halftone-printed. In detail, the sample sheet has 11 sample areas where only cyan is printed, and the cyan halftone dot area ratios are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, respectively, and 11 sample areas where only magenta is printed, and the magenta halftone dot area ratios are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, respectively. The sample area includes a pull area, 11 sample areas where only yellow is printed, where the yellow dot area percentages are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, and 11 sample areas where only black is printed, where the black dot area percentages are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%, respectively.

[0059] The varnish used was genuine varnish DUV-310. The varnish was applied to the sample area of ​​the sample sheet using a digital spot UV coater DDC-8000 manufactured by Duplo Co., Ltd., so that the coating thickness was 25 μm.

[0060] The ultraviolet irradiation intensities were 25%, 30%, 35%, 40%, and 45%. In other words, five ultraviolet irradiation intensities were tested. The sheet conveying speed was 5.2 m / min. In this case, the cumulative amount of ultraviolet light irradiated to the varnish was 0.19 J / cm for each of the ultraviolet irradiation intensities of 25%, 30%, 35%, 40%, and 45%. 2 ,0.238J / cm 2 , 0.285J / cm 2 , 0.333J / cm 2 , 0.38J / cm 2 It was.

[0061] Figures 5 to 8 summarize the experimental results. Figures 5 to 8 are in grayscale, so please also refer to the color screens of Figures 5 to 8 that are to be attached to the property submission form and submitted.

[0062] Figures 5 to 8 show the experimental results for cyan, magenta, yellow, and black, respectively. In each of Figures 5 to 8, sample areas with dot ratios of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% are arranged from right to left in the figure. In each of Figures 5 to 8, the sample areas in the first row are sample areas that have not been varnished or foil stamped. The sample areas in the second to sixth rows are sample areas that have been varnished, irradiated with ultraviolet light, and foil stamped, and are irradiated with ultraviolet light at ultraviolet irradiation intensities of 25%, 30%, 35%, 40%, and 45%.

[0063] In the sample areas in rows 2 to 6 of Figures 5 to 8, in the sample areas where the foil is attached, the cyan, magenta, yellow or black color printed in the sample area is naturally hidden by the foil and cannot be seen, while in the sample areas where the foil is not attached or is only partially attached, the cyan, magenta, yellow or black color printed in the sample area is visible. This is clearer when you refer to the color drawings in Figures 5 to 8 that will be submitted as attachments to the property submission document.

[0064] Experiments showed that the lower the dot area ratio, i.e., the higher the proportion of the underlying white color remaining, the more difficult it is for foil to adhere, and the higher the dot area ratio, i.e., the lower the proportion of the underlying white color remaining, the more likely it is that foil will adhere.

[0065] As shown in Figure 5, for cyan, when the UV irradiation intensity is 30%, the foil adheres when the dot area ratio is 70% or more, and when the dot area ratio is 20% or less, the foil does not adhere, and the cyan color printed in the sample area is visible. In this case, the difference in dot area ratio is 50 (70-20)%. When the UV irradiation intensity is 35%, the foil adheres when the dot area ratio is 90% or more, and when the dot area ratio is 50% or less, the foil does not adhere. In this case, the difference in dot area ratio is 40 (90-50)%. As shown in Figure 6, similar results were obtained for magenta as for cyan.

[0066] From this, it can be seen that in the case of one of the colors cyan and magenta, if the difference in dot area rate between the first area A1 and the second area A2 is 50% or more, by adjusting the integrated light amount, it is possible to fully cure the varnish applied to the first area A1 and semi-cure the varnish applied to the second area A2, coating the first area A1 with varnish and foil stamping the second area A2. Also, the integrated light amount in this case is 0.2 to 0.3 J / cm 2 is preferred.

[0067] As shown in FIG. 7, for yellow, when the UV irradiation intensity is 30%, the foil adheres when the dot area ratio is 40% or more, and when the dot area ratio is 10% or less, the foil does not adhere, and the yellow color printed in the sample area is visible. In this case, the difference in dot area ratio is 30 (40-10)%. When the UV irradiation intensity is 35%, the foil adheres when the dot area ratio is 50% or more, and when the dot area ratio is 20% or less, the foil does not adhere, and the yellow color printed in the sample area is visible. In this case, the difference in dot area ratio is 30 (50-20)%. When the UV irradiation intensity is 40%, the foil adheres when the dot area ratio is 70% or more, and when the dot area ratio is 30% or less, the foil does not adhere, and the yellow color printed in the sample area is visible. In this case, the difference in dot area ratio is 40 (70-30)%. When the UV irradiation intensity is 45%, the foil adheres when the dot area ratio is 80% or more, and when the dot area ratio is 40% or less, the foil does not adhere and the yellow color printed in the sample area is visible. In this case, the difference in dot area ratio is 40 (80-40)%. As shown in Figure 8, the same results were obtained for black as for yellow.

[0068] From this, it can be seen that in the case of one of the colors yellow and black, if the difference in dot area rate between the first area A1 and the second area A2 is 40% or more, by adjusting the integrated light amount, it is possible to fully cure the varnish applied to the first area A1 and semi-cure the varnish applied to the second area A2, coating the first area A1 with varnish and foil stamping the second area A2. Also, the integrated light amount in this case is 0.2 to 0.4 J / cm 2is preferred.

[0069] In this experiment, one of the colors cyan, magenta, yellow, and black was printed in one sample area, so the formula "(percentage of underlying white remaining) = 100 - (dot area ratio)" holds. When dot area ratios are set for each of cyan, magenta, yellow, and black in actual full-color printing and colors are expressed by mixing the colors, the cyan, magenta, yellow, and black dots partially overlap each other, so the "percentage of underlying white remaining" in formula 2 is greater than "100 - (total of dot area ratios for cyan, magenta, yellow, and black)."

[0070] Experiments have also shown that yellow and black tend to have more foil marks than cyan and magenta. Therefore, in Equation 3, the coefficient k c ,k m Rather, the coefficient k y ,k k It is preferable to make it small.

[0071] Next, the effects of this embodiment will be described. According to this embodiment, the varnish applied to the first area A1 on the surface of the sheet can be fully cured and the varnish applied to the second area A2 can be semi-cured by simply passing the sheet through the varnish application device 14 once. In other words, according to this embodiment, the first area A1 on the surface of the sheet can be coated with varnish and the second area A2 can be foil stamped by simply passing the sheet through the sheet decoration system 10 once.

[0072] Also, according to this embodiment, by passing the sheet through the sheet decoration system 10 only once, only the first area A1 is varnished and no foil is applied, and the second area A2 is foil-stamped on the varnish coating. Conventionally, to obtain a similar decoration, it was necessary to pass the sheet through the machine twice. In detail, in the first pass, varnish is applied to the first area A1 or both the first area A1 and the second area A2, and the varnish is fully cured, and in the second pass, varnish is applied to the second area A2, semi-cured, and foil is stamped on the varnish and the varnish is fully cured. In this case, it was difficult to completely prevent the misalignment between the first and second varnish application positions. In contrast, according to this embodiment, since the varnish is applied only once, the problem of misalignment of the varnish application position does not occur as in the past. Also, compared to the conventional method in which the sheet had to be passed through the machine twice, the effort and time required for sheet decoration, and therefore the cost, can be reduced.

[0073] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each processing step, and that such modifications are also within the scope of the present invention. Such modifications will be described below.

[0074] (Variation 1) The varnish application device 14 may be capable of executing a first mode in which the varnish applied to the first region is fully cured and the varnish applied to the second region is semi-cured as in the embodiment, and a second mode in which all the varnish applied to the sheet is fully cured. In the second mode, ultraviolet rays are irradiated under irradiation conditions in which the cumulative amount of ultraviolet rays irradiated to the varnish is greater than in the first mode. For example, the ultraviolet lamp 48 may irradiate ultraviolet rays with a higher ultraviolet intensity in the second mode than in the first mode. The control device 20 may receive a selection from the user as to whether to execute the first mode or the second mode.

[0075] (Variation 2) Although not specifically mentioned in the embodiment, the thickness of the varnish affects the full curing and semi-curing of the varnish. Therefore, the irradiation conditions may be adjusted taking into account the thickness of the varnish. For example, the thicker the varnish is, the higher the ultraviolet intensity of the ultraviolet light to be irradiated, and the thinner the varnish is, the lower the ultraviolet intensity of the ultraviolet light to be irradiated.

[0076] (Variation 3) In the embodiment and the above-mentioned modified example, the case of foil stamping on semi-cured varnish, that is, foil stamping as a transfer process, has been described, but the present invention is not limited to this, and other transfer processes may be performed on the semi-cured varnish. For example, instead of the foil stamping device 16, a transfer device that performs a transfer process called lamicoat processing may be provided, and a web with fine irregularities formed on its surface may be brought into close contact with the semi-cured varnish, and the fine irregularities may be transferred to the varnish.

[0077] The above-described embodiment can be generalized to provide the following aspects.

[0078] [Aspect 1] A coating step of coating a varnish having ultraviolet curing properties on a first region on a surface of the sheet and a second region having a lower ultraviolet reflectance than the first region; a curing step of irradiating the varnish applied to the first region and the second region with ultraviolet light to harden the varnish applied to the first region and semi-harden the varnish applied to the second region; a transfer step of performing a predetermined transfer process on the semi-hardened varnish; A sheet decoration method comprising:

[0079] [Aspect 2] The sheet decoration method according to embodiment 1, further comprising, before the applying step, a printing step of printing the first region in a color having a higher ultraviolet reflectance than the second region.

[0080] [Aspect 3] 3. The sheet decoration method according to embodiment 1 or 2, further comprising, before the coating step, a printing step of printing the second region in a color having a lower ultraviolet reflectance than the first region.

[0081] Aspect 4 The method further includes a printing step of printing the second area in black before the application step, 4. The sheet decorating method according to any one of aspects 1 to 3, wherein the transfer treatment is a treatment of transferring a transfer substance from a transfer web.

[0082] Aspect 5 A sheet decoration method according to any one of aspects 1 to 4, wherein the curing step comprises irradiating the first region with ultraviolet light under irradiation conditions according to the ultraviolet light reflectances of both the first region and the second region.

[0083] Aspect 6 The surface of the sheet before printing in the printing step is white, A sheet decoration method according to any one of aspects 2 to 4, in which the curing step involves irradiating ultraviolet light under irradiation conditions that depend on the proportion of the white surface of the sheet remaining in the first region and the proportion of the white surface of the sheet remaining in the second region.

[0084] Aspect 7 The surface of the sheet before printing in the printing step is white, The sheet decoration method according to any one of aspects 2 to 4, wherein the curing step comprises irradiating the ultraviolet light under irradiation conditions according to the dot rate of the first region and the dot rate of the second region.

[0085] Aspect 8 A sheet decoration method according to any one of aspects 1 to 7, wherein the irradiation conditions include conditions that affect the integrated amount of ultraviolet light irradiated onto the varnish.

[0086] Aspect 9 9. The sheet decoration method according to any one of aspects 1 to 8, wherein the irradiation conditions include at least one of the irradiation intensity of the ultraviolet rays, the irradiation distance of the ultraviolet rays, and the conveying speed of the sheet. [Explanation of symbols]

[0087] 1 sheet decoration system, 12 printing device, 14 varnishing device, 16 foil stamping device, 46 varnish discharge section, 48 ultraviolet lamp.

Claims

1. A coating step of coating a varnish having ultraviolet curing properties on a first region on a surface of the sheet and a second region having a lower ultraviolet reflectance than the first region; a curing step of irradiating the varnish applied to the first region and the second region with ultraviolet light to harden the varnish applied to the first region and semi-harden the varnish applied to the second region; a transfer step of performing a predetermined transfer process on the semi-hardened varnish; A sheet decoration method comprising:

2. The sheet decoration method according to claim 1 , further comprising, before the application step, a printing step of printing the first region in a color having a higher ultraviolet reflectance than the second region.

3. The sheet decoration method according to claim 1 , further comprising, before the application step, a printing step of printing the second region in a color having a lower ultraviolet reflectance than the first region.

4. a printing step of printing the second area in black before the application step, 2. The sheet decoration method according to claim 1, wherein the transfer process is a process of transferring a transfer material from a transfer web.

5. The sheet decoration method described in claim 1, further comprising a printing step of printing the first area and the second area before the coating step so that the difference between the ultraviolet reflectance of the first area and the ultraviolet reflectance of the second area is greater than or equal to a predetermined threshold value.

6. The sheet decoration method described in claim 1, further comprising a printing step of printing on a sheet having a white surface before the application step, the printing step printing the first area and the second area so that the difference between the proportion of the white surface of the sheet remaining in the first area and the proportion of the white surface of the sheet remaining in the second area is greater than or equal to a predetermined threshold value.

7. The sheet decoration method described in claim 1, further comprising a printing step of printing on a sheet having a white surface before the application step, wherein the first area and the second area are printed so that the difference between the dot area rate of the first area and the dot area rate of the second area is equal to or greater than a predetermined threshold value.

8. 8. The sheet decoration method according to claim 1, wherein in the curing step, the ultraviolet light is irradiated under irradiation conditions according to the ultraviolet light reflectances of both the first region and the second region.

9. The surface of the sheet before printing in the printing step is white, A sheet decoration method as described in any one of claims 2 to 7, wherein in the hardening process, ultraviolet light is irradiated under irradiation conditions that correspond to the proportion of the white surface of the sheet remaining in the first region and the proportion of the white surface of the sheet remaining in the second region.

10. The surface of the sheet before printing in the printing step is white, 8. The sheet decoration method according to claim 2, wherein in the curing step, ultraviolet light is irradiated under irradiation conditions according to the dot area ratio of the first region and the dot area ratio of the second region.

11. The sheet decoration method according to claim 1 , wherein the irradiation conditions include conditions that affect an integrated amount of ultraviolet light irradiated onto the varnish.

12. The sheet decoration method according to claim 11 , wherein the irradiation conditions include at least one of the irradiation intensity of the ultraviolet rays, the irradiation distance of the ultraviolet rays, and the conveying speed of the sheet.

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