WO2021172344A1

WO2021172344A1 - Printing sheet and printed matter

Info

Publication number: WO2021172344A1
Application number: PCT/JP2021/006828
Authority: WO
Inventors: 正藤本; 岳志藤原
Original assignee: 正藤本; 株式会社ハプコ
Priority date: 2020-02-25
Filing date: 2021-02-24
Publication date: 2021-09-02
Also published as: JPWO2021172344A1

Abstract

[Problem] To provide a printing sheet and printed matter which exhibit high aesthetic properties. [Solution] A printing sheet 19 is principally equipped with a diffusion layer 11, a substrate layer 12 and an ink-receiving layer 13. The substrate layer 12 is an optically transparent sheet-like member which comprises an arbitrary transparent material, and for example, could be a resin sheet comprising a polyester resin such as polyethylene terephthalate. The diffusion layer 11 has a contrast ratio of 60-94%, inclusive, and is provided on the rear surface of the substrate layer 12. The diffusion layer 11 is tightly adhered to the substrate layer 12 by being coated onto the substrate layer 12 or being adhered thereto by an adhesive.

Description

Printed sheet and printed matter

The present invention relates to a printing sheet for printing an image and a printed matter obtained by printing an image on the printing sheet.

An inkjet recording sheet having a function as an illumination for observing by irradiating light from the rear is known. This inkjet recording sheet conceals the support, the ink receiving layer provided on the support, and the optical transmission density of 0.15 or more provided between the ink receiving layer and the support or on the opposite surface of the ink receiving layer. It has a layer (Patent Document 1).

JP 2000-272228

However, since the concealing layer having such a high optical transmission density of 0.15 or more does not sufficiently transmit light, the aesthetics may deteriorate.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a printed sheet and a printed matter having high aesthetics.

The printing sheet according to the first invention of the present application includes a light-transmitting base material layer, an ink receiving layer provided on the surface of the base material layer, and a diffusion layer provided on the back surface of the base material layer, and is a diffusion layer. Has a concealment rate of 60% or more and 94% or less.

The diffusion layer is preferably adhered to the back surface of the base material layer.

There are a plurality of base material layers, and each base material layer is preferably in close contact with the adjacent base material layer, and the base material layer is preferably in close contact with the adjacent base material layer using an adhesive sheet.

The diffusion layer may have a concealment rate of 70% or more and 92% or less, or may have a concealment rate of 72% or more and 88% or less.

In the printing sheet, it is preferable that the diffusion layer and the base material layer adjacent to the diffusion layer are in close contact with each other to form a diffusion sheet, and the haze value of the diffusion sheet is 70% or more and less than 100%.

In the printing sheet, it is preferable that the diffusion layer and the base material layer adjacent to the diffusion layer are in close contact with each other to form a diffusion sheet, and the total transmittance of the diffusion sheet is 45% or more and 100% or less.

The printing sheet preferably has a thickness of 80 μm or more and 300 μm or less.

The arithmetic mean roughness Ra of the surface of the ink receiving layer in the printing sheet is preferably 0.3 μm or more and 2.0 μm or less.

The printed matter according to the second invention of the present application includes a light-transmitting base material layer, an ink receiving layer provided on the surface of the base material layer, and a diffusion layer provided on the back surface of the base material layer, and the diffusion layer is 60. A printing sheet having a hiding ratio of% or more and 94 or less, and an ink layer provided on the ink receiving layer are provided.

It is preferable that the highlight luminance ratio is 75% or more, the RMS granularity is 9.0 × ^10-2 or less, and the shadow luminance ratio is 0.065% or less.

The arithmetic mean roughness Ra of the ink receiving layer in the printed matter is preferably 0.3 μm or more and 2.0 μm or less.

According to the present invention, it is possible to provide a printed sheet and a printed matter having high aesthetics.

It is the schematic which shows the printing sheet and the printed matter by 1st Embodiment of this invention. It is the schematic which shows the printing sheet and the printed matter by the 2nd Embodiment of this invention. It is the schematic which shows the printing sheet and the printed matter by the comparative example 4. FIG. It is the schematic which shows the printing sheet and the printed matter by the comparative example 1 and 5. 6 is a graph showing Examples 1 to 7 and Comparative Examples 1 to 4 and 6 to 10. It is a graph which shows Example 1 and Comparative Example 1. It is a graph which shows the comparative example 5. In Example 9 and Comparative Example 12, it is a photograph which magnified the part where the shadow brightness was measured 30 times.

<Printed sheet and printed matter>
Hereinafter, the printed sheet 19 and the printed matter 10 according to the first embodiment will be described with reference to FIG.

The printing sheet 19 mainly includes a diffusion layer 11, a base material layer 12, and an ink receiving layer 13.

The base material layer 12 is a sheet-like member having light transmission and is made of an arbitrary transparent material, for example, a vinyl resin such as polyvinyl alcohol or polyvinyl acetate, an acrylic resin such as poly (meth) acrylate, and the like. It is a resin sheet made of a polyolefin resin such as polyethylene or polypropylene, and a polyester resin such as polyethylene terephthalate.

The diffusion layer 11 is a layer having a concealment rate of 60% or more and 94% or less, and is provided on the back surface of the base material layer 12. The diffusion layer 11 is provided on the base material layer 12 by coating or adhered with an adhesive so as to be in close contact with the base material layer 12. Here, adhesion means that there is no gas between the diffusion layer 11 and the base material layer 12. The concealment ratio is the ratio LB / LW (%) of the lightness LW of the light transmitted through the measurement object placed on the white glass plate and the lightness LB of the light transmitted through the measurement object placed on the black glass plate. ). The diffusion sheet 17 is formed by the diffusion layer 11 and the base material layer 12. The haze value of the diffusion sheet 17 is preferably in the range of 70% or more and less than 100%, and the total transmittance of the diffusion sheet 17 is preferably in the range of 45% or more and 100% or less. Since the base material layer 12 has sufficient transparency, the hiding rate, haze value, and total transmittance of the diffusion layer 11 are equal to the hiding rate, haze value, and total transmittance of the diffusion sheet, respectively.

The ink receiving layer 13 is provided on the surface of the base material layer 12, for example, by being applied. The ink receiving layer 13 may have a known composition, and preferably contains, for example, a polymethacrylic acid ester resin such as polymethylmethacrylate, ethylpolymethacrylate, and butylpolymethacrylate. These can preferably absorb and fix a solvent ink containing 1-ethoxy-2- (2-methoxyethoxy) ethane having a weight ratio of 65 to 80% of the whole, for example. The thickness of the ink receiving layer 13 is preferably in the range of, for example, about 20 to 100 μm.

The thickness of the printing sheet 19 is preferably in the range of 80 μm or more and 300 μm or less. Printing is performed on the surface of the printing sheet 19 where the ink receiving layer 13 is exposed. As a result, the ink layer 14 is formed on the ink receiving layer 13, and the printed matter 10 is obtained. Printing is preferably performed by, for example, an inkjet printer. Hereinafter, the structure of the printed matter 10 is referred to as structure A.

An LED surface light source 50 that irradiates light is installed on the diffusion layer 11 in the printed matter 10 and the printing sheet 19. The viewer observes the light transmitted through the printed matter 10 from the ink layer 14 side.

Next, with reference to FIG. 2, the printing sheet 29 and the printed matter 20 according to the second embodiment will be described.

The printing sheet 29 mainly includes a diffusion layer 21, a first base material layer 22, an ink receiving layer 23, a second base material layer 25, and an adhesive layer 26. Since the first base material layer 22 is the same as the base material layer 12 according to the first embodiment, the description thereof will be omitted.

The diffusion layer 21 is a layer having a concealment rate of 60% or more and 94% or less, and is provided on the back surface of the first base material layer 22. The diffusion layer 21 is provided on the first base material layer 22 by coating or is provided by being adhered with an adhesive, and is in close contact with the first base material layer 22. Here, adhesion means that there is no gas between the diffusion layer 21 and the first base material layer 22. The diffusion sheet 27 is formed by the diffusion layer 21 and the first base material layer 22. The concealment rate, haze value, and total transmittance are the same as those in the first embodiment.

Since the second base material layer 25 is the same as the base material layer 12 according to the first embodiment, the description thereof will be omitted. The ink receiving layer 23 is provided on the surface of the second base material layer 25, for example, by being applied. The ink receiving layer 23 and the second base material layer 25 form a receiving sheet 28.

The diffusion sheet 27 and the receiving sheet 28 are provided by being adhered to each other in the first base material layer 22 and the second base material layer 25 with an adhesive, and are in close contact with each other. Here, adhesion means that there is no gas between the first base material layer 22 and the second base material layer 25.

The thickness of the printing sheet 29 is preferably in the range of 80 μm or more and 300 μm or less. Printing is performed on the surface of the printing sheet 29 where the ink receiving layer 23 is exposed. As a result, the ink layer 24 is formed on the ink receiving layer 23, and the printed matter 20 is obtained. Printing is preferably performed by, for example, an inkjet printer. Hereinafter, the structure of the printed matter 20 is referred to as structure B.

An LED surface light source 50 that irradiates light is installed on the diffusion layer 21 of the printed matter 20 and the printing sheet 29. The viewer observes the light transmitted through the printed matter 20 from the ink layer 24 side.

Next, the effect of the present invention will be described with reference to examples. First, each test evaluation method used in the examples will be described.

<Reception sheet>
In Examples 1 to 4 and 7 to 10 and Comparative Examples 1 to 13, commercially available receiving sheets R1 to R5 having a transparent PET film as a base material layer and an ink receiving layer on one side thereof were used. The substrate layer is colorless and transparent for all of the receiving sheets R1 to R5, the receiving layer is colorless and transparent for the receiving sheet R1, the receiving sheet R2 is milky white, and the receiving layers R3 to R5 are translucent. The receiving layer of the receiving sheet R2 also serves as a diffusion layer. Receptive layer thickness (μm), overall thickness (total thickness) (μm), arithmetic mean roughness (surface roughness) Ra (μm), total transmittance (%), haze (haze) in the receiving sheets R1 to R5. %), Concealment rate (%), manufacturer and model number are shown in Table 1. The arithmetic mean roughness Ra was measured in accordance with JIS B 0601. That is, using a laser microscope (manufactured by KEYENCE CORPORATION, model number: VK-X1100), within the range of 4.3 mm × 0.5 mm on the surface of the printing sheet, within the range of 0.5 mm with 4.3 mm as the reference length. The surface roughness on 9 lines was measured with. Then, the arithmetic average roughness Ra was calculated based on the contour curve obtained for each line, the average value of 9 lines was obtained, and this was used as the arithmetic average roughness Ra. The arithmetic mean roughness Ra is preferably 0.3 μm or more and 2.0 μm. If the arithmetic mean roughness Ra is 0.3 μm or more, blocking of printed matter can be suppressed, and if it is 2.0 μm or less, the surface roughness, that is, the unevenness of the surface is difficult for the viewer to visually recognize.

<Diffusion sheet>
In Examples 1 to 7 and Comparative Examples 1 to 10, diffusion sheets D1 to D7 having a matte coating layer on one side of a transparent PET film were used. The diffusion sheets D1 to D7 are shown in Table 2.

<Thickness measurement method>
The thickness of the printing sheet is measured using a dial gauge (manufactured by Ozaki Seisakusho Co., Ltd., model number: Peacock G-7C), and the ink receiving layer is measured using a digital microscope (manufactured by KEYENCE Co., Ltd., model number: VH-Z100UR). The thickness of the ink was measured.

<Measurement method of haze value and light transmittance>
Using a haze meter (manufactured by Suga Test Instruments Co., Ltd., model number: HZ-V3), measure the haze value of the receiving sheet and diffusion sheet according to JIS K 7361, and measure the haze value of the receiving sheet and diffusion sheet according to JIS K 7136. The light transmittance of was measured.

<Measurement method of concealment rate>
The receiving sheet and the diffusion sheet shown in Tables 1 and 2 are placed on a white 5 cm × 5 cm glass plate with the diffusion layer side facing the glass plate side, and a spectrocolorimeter (manufactured by EC tool, model number: wy054). Was used to measure the L * values in the L * a * b * colorimetric system at any five points on the receiving sheet and the diffusion sheet, and the average value of the five values was taken as LW. The L * value of the white glass plate is 81.5. Similarly, using a black glass plate, the L * value was measured at the same five points as the white one, and the average value of the five values was defined as LB. The L * value of the black glass plate is 28.5. Then, LB / LW (%) was used as the concealment rate.

<Highlight brightness ratio>
An unprinted printing sheet is placed on the light emitting surface of a light source panel (manufactured by TRYTEC Co., Ltd., model number: Treviewer A4-500W) having a brightness of 1500 cd, and a luminance meter (TES Electrical Electrical Corp., model number: TES) is placed. Using -137), the brightness of the surface of the printing sheet was measured at 5 points at arbitrary positions. The brightness of the light source panel was L0, the average value of the brightness at any five points was Ln, and the highlight brightness ratio was Ln / L0 (%). The larger the highlight luminance ratio, the brighter and whiter the white part in the printed image, and the higher the aesthetics of the printed image.

<Shadow brightness ratio>
Using an inkjet printer (manufactured by Seiko Epson Corporation, model number: SC-S80650) on the A4 size printing sheet, cyan: 100, magenta: 100, yellow: 100, black: 100, 30 passes, printer wide folding It was printed by the method and a printed matter was obtained. Then, this printed matter is placed on the light emitting surface of a light source panel (manufactured by TRYTEC Co., Ltd., model number: Treviewer A4-500W) having a brightness of 1500 cd, and a luminance meter (manufactured by TES Electrical Electrical Corp., model number: TES-137) is used. The brightness of the printed matter surface was measured at any five points. The brightness of the light source panel was L0, the average value of the brightness at any five points was Ln, and the shadow brightness ratio was Ln / L0 (%). When the shadow luminance ratio is small, the black portion in the printed image becomes blacker and the printed image becomes more aesthetically pleasing. In order to perform the measurement at the same location in each Example and Comparative Example, marking was included in the image data to be printed, and the shadow luminance ratio was measured at the marked position.

<RMS granularity>
A4 size printing sheet using an inkjet printer (manufactured by Seiko Epson Corporation, model number: S80650), cyan: 7.5, magenta: 60, yellow: 30, black: 0, single layer 30 passes, printer Printing was performed by the wide folding method to obtain a printed matter. Then, this printed matter is placed on the light emitting surface of a light source panel (manufactured by TRYTEC Co., Ltd., model number: Trebuer A4-500W) having a brightness of 1500 cd, and the surface of the printed matter is magnified by a 15x magnifying glass (manufactured by Phoenix, model number: Ph-). 014) was used to magnify, and a digital camera (manufactured by Samsung Electronics Co., Ltd., model number: Galaxy S8) was brought into close contact with the viewing port of this magnifying glass to take an image. Using image processing software (manufactured by Adobe Systems Co., Ltd., model number: Photoshop CC), the captured image is converted to a grayscale image, and in this grayscale image, pixel values at 100 locations are measured every 20 μm on a straight line. Then, the standard deviation of the obtained pixel values was taken as the RMS granularity. When the RMS graininess is low, the graininess of the printed image is improved and the aesthetics of the printed image is improved. Graininess refers to a random grainy texture caused by variations in the density of a photographic image, and the worse the graininess (the coarser the grain), the grainier the photograph becomes. In order to perform the measurement at the same location in each Example and Comparative Example, marking was included in the image data to be printed, and the RMS granularity was measured at the marked position.

[Example 1]
The receiving sheet R1 (manufactured by Niei Kako Co., Ltd., model number: SPT) shown in Table 1 was printed using software RIP (manufactured by ONYX Graphics, model number: Poster SHOP) with settings according to each evaluation method. Then, the diffusion layer of the diffusion sheet D3 shown in Table 2 is attached to the back surface of the printed receiving sheet R1 with a double-sided acrylic adhesive sheet (manufactured by Kimoto Co., Ltd., model number: PTT25) while expelling air, according to the present invention. I got a printed matter. Regarding the measurement of the highlight luminance ratio, the unprinted receiving sheet R1 is bonded to the diffusion sheet D3 with a double-sided acrylic adhesive sheet (manufactured by Kimoto Co., Ltd., model number: PTT25) in the same manner as the printed matter of the present invention. Sheet was used. In this respect, hereinafter, the term “printed receiving sheet R1” includes the unprinted receiving sheet R1. The print sheet included in this printed matter is the structure B. The double-sided acrylic adhesive sheet has a re-peelable surface and a strong adhesive surface, and a receiving sheet is attached to the re-peelable surface and a diffusion sheet is attached to the strong adhesive surface. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 1]
The printed receiving sheet R1 (reference numerals 23 to 25 in FIG. 4) contained in the printing sheet obtained in Example 1 is peeled off, and a new diffusion sheet D3 (manufactured by Kimoto Co., Ltd., model number: 100SXE, reference numeral 4) is peeled off. It was superposed on 27) and used as Comparative Example 1. Since the double-sided acrylic adhesive sheet is not used between the printed receiving sheet R1 and the new diffusion sheet D3, the printed receiving sheet R1 and the new diffusion sheet D3 are not in close contact with each other. This structure D (

reference numerals

40 and 49 in FIG. 4) has the same structure as that of the first embodiment except that the receiving sheet R1 is only superposed on the new diffusion sheet D3 and is not in close contact with the new diffusion sheet D3. Table 3 shows the results of each measurement of the printed sheet (reference numeral 49 in FIG. 4) and the printed matter (reference numeral 40 in FIG. 4) obtained thereby.

[Example 2]
The printed receiving sheet R1 used in Comparative Example 1 was peeled off and adhered to a diffusion sheet D4 (manufactured by Kimoto Co., Ltd., model number: 75K2S) using a double-sided acrylic adhesive sheet to obtain Example 2. Example 2 has the same structure as that of Example 1 except that the diffusion sheet D4 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 3]
The printed receiving sheet R1 used in Example 2 was peeled off and adhered to a diffusion sheet D2 (manufactured by Otsuki Kogyo Co., Ltd., model number: GM10) using a double-sided acrylic adhesive sheet to obtain Example 3. Example 3 has the same structure as that of Example 1 except that the diffusion sheet D2 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 2]
The printed receiving sheet R1 used in Example 3 was peeled off and brought into close contact with the diffusion sheet D1 (manufactured by Kimoto Co., Ltd., model number: 100SP6F) using a double-sided acrylic adhesive sheet to obtain Comparative Example 2. Comparative Example 2 has the same structure as that of Example 1 except that the diffusion sheet D1 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 4]
The printed receiving sheet R1 used in Comparative Example 2 was peeled off and adhered to a diffusion sheet D5 (manufactured by Kimoto Co., Ltd., model number: 50SDN) using a double-sided acrylic adhesive sheet to obtain Example 4. Example 4 has the same structure as that of Example 1 except that the diffusion sheet D5 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 3]
The printed receiving sheet R1 used in Example 4 was peeled off and adhered to a diffusion sheet D6 (manufactured by Kimoto Co., Ltd., model number: 75PWX) using a double-sided acrylic adhesive sheet to obtain Comparative Example 3. Comparative Example 3 has the same structure as that of Example 1 except that the diffusion sheet D6 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 5]
After performing a corona discharge treatment on the opposite side of the diffusion layer of the diffusion sheet D3, a resin for the ink receiving layer (manufactured by OSG System Products Co., Ltd., model number: 250HANDL) (manufactured by Takamatsu Oil & Fat Co., Ltd., model number: 250HANDL) is used. ES-969MC) was uniformly coated, placed in a blower dryer, and dried at 100 ° C. for 10 minutes to obtain a printing sheet. The thickness of the ink receiving layer of the obtained printing sheet was 15 μm. A printed matter of structure A was obtained on this printing sheet by using the same printing method as in Example 1. The obtained printing sheet and printed matter were placed on the surface of the light source panel, and the results of each measurement are shown in Table 3.

[Example 6]
An ink receiving layer was formed on the diffusion sheet D4 shown in Table 2 to obtain a printing sheet of Example 6, and the printed matter of Example 6 was obtained by printing on the sheet. All are the same as in Example 5 except that the diffusion sheet D4 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 7]
The printed receiving sheet R1 used in Example 2 was peeled off and adhered to a diffusion sheet D7 (manufactured by Lami Corporation, model number: SPB) using a double-sided acrylic adhesive sheet to obtain Example 7. Example 7 has the same structure as that of Example 1 except that the diffusion sheet D7 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 4]
A printed matter having a structure C (

reference numerals

30 and 39 in FIG. 3) by printing on the receiving sheet R2 (manufactured by Toyobo Co., Ltd., model number: MT701, reference numeral 39 in FIG. 3) shown in Table 1 to form an ink layer 34. Reference numeral 30) in FIG. 3 was obtained, and this was designated as Comparative Example 4. The printing method is the same as in Example 1. The receiving sheet R2 mainly includes an ink receiving layer 33 and a second base material layer 35, and exhibits a milky white color. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 5]
The receiving sheet R1 printed with the print setting values of cyan: 8.5, magenta: 70, and yellow: 35 was superposed on a new diffusion sheet D3 to be used as Comparative Example 5, and the RMS granularity was measured. All other measurement results are those of Comparative Example 1. The results obtained in this way are shown in Table 3.

[Comparative Example 6]
The printed receiving sheet R1 used in Example 3 was peeled off and superposed on the diffusion sheet D1 (manufactured by Kimoto Co., Ltd., model number: 100SP6F) to obtain Comparative Example 6. Comparative Example 6 has the same structure as that of Comparative Example 1 except that the diffusion sheet D1 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 7]
The printed receiving sheet R1 used in Example 3 was peeled off and superposed on the diffusion sheet D2 (manufactured by Otsuki Kogyo Co., Ltd., model number: GM10) to obtain Comparative Example 7. Comparative Example 7 has the same structure as that of Comparative Example 1 except that the diffusion sheet D2 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 8]
The printed receiving sheet R1 used in Example 3 was peeled off and superposed on a diffusion sheet D4 (manufactured by Kimoto Co., Ltd., model number: 75K2S) to obtain Comparative Example 8. Comparative Example 8 has the same structure as that of Comparative Example 1 except that the diffusion sheet D4 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 9]
The printed receiving sheet R1 used in Example 3 was peeled off and superposed on a diffusion sheet D5 (manufactured by Kimoto Co., Ltd., model number: 50SDN) to obtain Comparative Example 9. Comparative Example 9 has the same structure as that of Comparative Example 1 except that the diffusion sheet D5 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 10]
The printed receiving sheet R1 used in Example 3 was peeled off and superposed on a diffusion sheet D6 (manufactured by Kimoto Co., Ltd., model number: 75PWX) to obtain Comparative Example 10. Comparative Example 10 has the same structure as that of Comparative Example 1 except that the diffusion sheet D6 is used. Table 3 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

Again, in order to make the measurement conditions the same, the same printed receiving sheet R1 was used in Examples 1 to 4 and 7 and Comparative Examples 1 to 3 and 5 to 10.

[Example 8]
A printed matter having a structure B is obtained by adhering a receiving sheet R3 having an adhesive on the back surface to a diffusion sheet D7 (manufactured by Lami Corporation, model number: SPB) and then printing to form an ink layer 24. Therefore, it was referred to as Example 8. Example 8 is the same as Example 7 except that the receiving sheet R3 is used. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 11]
The printed receiving sheet R3 used in Example 8 was peeled off, the adhesive layer on the back surface of the receiving sheet R3 was removed with toluene, and the printed matter having the structure D was obtained by superimposing it on the diffusion sheet D7. It was set to 11. Comparative Example 11 is the same as that of Example 8 except for these points. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 9]
A printed matter having a structure B is obtained by adhering a receiving sheet R4 having an adhesive on the back surface to a diffusion sheet D7 (manufactured by Lami Corporation, model number: SPB) and then printing to form an ink layer 24. Therefore, it was referred to as Example 9. Example 9 is the same as Example 8 except that the receiving sheet R4 is used. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 12]
The printed receiving sheet R4 used in Example 9 was peeled off, the adhesive layer on the back surface of the receiving sheet R4 was removed with toluene, and the printed matter having the structure D was obtained by superimposing it on the diffusion sheet D7. It was set to 12. Comparative Example 12 is the same as that of Example 9 except for these points. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Example 10]
The entire surface of the receiving sheet R1 was sandblasted so that the arithmetic average roughness Ra of the surface was 0.3 μm. After bonding using a sheet (manufactured by Kimoto Co., Ltd., model number: PTT25), a printed matter having a structure B is obtained by printing on a sandblasted surface to form an ink layer 24, and the same as in Example 10. bottom. Example 10 is the same as Example 8 except that the receiving sheet R5 is used. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

[Comparative Example 13]
The printed receiving sheet R5 used in Example 10 was peeled off, the double-sided acrylic adhesive sheet was removed using toluene, and the printed matter having the structure D was obtained by stacking it on the diffusion sheet D7, which was referred to as Comparative Example 13. Comparative Example 13 is the same as Example 10 except for these points. Table 4 shows the results of each measurement of the printed sheet and printed matter obtained in this manner.

<Evaluation>
Comparing Example 1 or Example 5 with Comparative Example 1, the highlight luminance ratio of Example 1 is 93.9%, the RMS granularity is 8.5 × ^10-2 , and the highlight of Example 5 is The brightness ratio is 94.2% and the RMS granularity is 8.2 × 10 ^-2 , whereas the highlight brightness ratio of Comparative Example 1 is 93.6% and the RMS granularity is 11.3 × 10 ^-2. Met. From this, it was found that the RMS granularity can be improved while maintaining the highlight luminance ratio by using the structure A or B.

Comparing Examples 1 to 5 with Comparative Example 4, the highlight luminance ratio of Examples 1 to 5 having the structure A or B is 87.0 to 99.8%, and the RMS granularity is 8.1 × 10 ^{−. While it was 2} to 8.6 × ^10-2 , the highlight luminance ratio of Comparative Example 4 having the structure C was 72.5%, and the RMS granularity was 8.4 × ^10-2 . From this, it was found that by using the structure A or B, a higher highlight luminance ratio than that of the structure C can be obtained while maintaining the same low RMS granularity as the structure C.

Comparing Example 1 or Example 5 with Comparative Example 1, the highlight luminance ratio of Example 1 having structure B is 93.9%, the shadow luminance ratio is 0.011%, and the embodiment having structure A. The highlight luminance ratio of Example 5 is 94.2 and the shadow luminance ratio is 0.011%, whereas the highlight luminance ratio of Comparative Example 1 having the structure D is 93.6% and the shadow luminance ratio is 0. It was 024%. From this, it was found that by using the structure A or B, a shadow luminance ratio lower than that of the structure D can be obtained while maintaining a high highlight luminance ratio similar to that of the structure D.

Comparing Examples 1 to 5 with Comparative Examples 1 to 4, low RMS granularity can be obtained by using the diffusion sheets D2, D3, D4, and D5 having a diffusion layer hiding ratio of 60% or more and 94% or less. It turned out to be obtained. In particular, Example 3 and Comparative Example 2 have the same structure B and the receiving sheet R1 and differ in that the diffusion sheets are D2 and D1, respectively. When comparing Example 3 and Comparative Example 2, the diffusion layer In Example 3 using the diffusion sheet D2 having a concealment rate of 72.6%, the diffusion sheet D1 having an RMS granularity of 8.6 × ^10-2 and a diffusion layer hiding rate of 59.2% was used. in Comparative example 2 was used, RMS granularity was 11.9 × ^{10 -2.} Here, as the concealment rate decreases, the RMS granularity increases, and the printed image tends to become conspicuous. From these facts, it was found that the lower limit of the concealment rate capable of maintaining low RMS granularity is about 60 to 72%.
The haze value of the diffusion sheet D2 used in Example 3 is 79.1%, while the haze value of the diffusion sheet D1 used in Comparative Example 2 is 69.2%. From these facts, it was found that the lower limit of the haze value capable of maintaining the low RMS granularity is about 70 to 79%.
Further, Example 4 and Comparative Example 3 have the same structure B and the receiving sheet R1 and differ in that the diffusion sheets are D5 and D6, respectively. However, when Example 4 and Comparative Example 3 are compared, the diffusion layer In Example 4 using the diffusion sheet D5 having a concealment rate of 88%, a comparative example using the diffusion sheet D6 having a highlight luminance ratio of 87.0% and a diffusion layer hiding rate of 94.8%. In No. 3, the highlight luminance ratio was 71.4%. Here, as the concealment ratio increases, the highlight luminance ratio decreases, and the printed image tends to become dark. From these facts, it was found that the upper limit of the concealment rate capable of maintaining a high highlight luminance ratio is about 88 to 94%.
Further, the haze value of the diffusion sheet D5 used in Example 4 is 91.4% and the total transmittance is 62.0%, while the haze value of the diffusion sheet D6 used in Comparative Example 3 is 92. It is 9% and the total transmittance is 40.5%. From these facts, it was found that the upper limit of the haze value capable of maintaining a high highlight luminance ratio is less than about 93%, and the lower limit of the total transmittance is about 45 to 60%.

The RMS granularity and concealment rate of Examples 1 to 7 and Comparative Examples 1 to 4 and 6 to 10 will be described with reference to FIG. Comparative Example 5 was excluded because the printing conditions were different from those of the other examples, as will be described later.
Circular markers indicate Examples 1 to 7 having structure A or structure B, square markers indicate Comparative Examples 2 and 3 having structure B, and solid lines are obtained by regression analysis of these data. The regression curve is shown. The R-squared value of this regression curve is 0.9936, which is a sufficient approximation of Examples 1 to 7 and Comparative Examples 2 and 3 having structure A or structure B.
Triangular markers indicate Comparative Examples 1, 4 and 6-9 having structure C or structure D, and dashed lines indicate regression curves obtained by regression analysis of these data. The R-squared value of this regression curve is 0.9927, which is a sufficient approximation of Comparative Examples 1, 4, and 6 to 9 having structure C or structure D.
The solid lines representing structures A and B are close to the broken lines representing structures C and D at points where the concealment rate is 59% and 95 to 97%, and are below the range of 60 to 94%. .. Therefore, it was found that the RMS granularity of the structures A and B was smaller than the RMS granularity of the structures C and D in the range of the concealment rate of 60 to 94%, and took a preferable value. Further, it was found that Examples 1 to 7 were included in the range of the concealment rate of 70% or more and 92% or less, and Examples 1 to 6 were included in the range of the concealment rate of 72% or more and 88% or less.
From the above, the hiding rate of the diffusion layer is preferably 60% or more and 94% or less, more preferably 70% or more and 92% or less, and further preferably 72% or more and 88% or less. The haze value of the diffusion sheet is preferably 70% or more and less than 92%, more preferably 75% or more and less than 92%, and even more preferably 90% or more and less than 92%. The total transmittance of the diffusion sheet is preferably 45% or more and 100% or less, more preferably 50% or more and 100% or less, and even more preferably 60% or more and 100% or less.

The comparison between Example 1 and Comparative Example 5 will be described with reference to Comparative Example 1. FIG. 6 is a graph showing pixel values at 100 locations measured with respect to the RMS granularity of Example 1 and Comparative Example 1. The pixel value is a ratio calculated by assuming that the gray scale K value (black value) is 100% for pure black and 0% for white. The average value of these pixel values, Example 1, 0.484 × ^{10 -2,} there is a difference that can not be ignored as Comparative Example 1, 0.438 × ^{10 -2.} Therefore, Comparative Example 5 was printed with the print setting values set to cyan: 8.5, magenta: 70, and yellow: 35 so that the average values of the pixel values were substantially the same. FIG. 7 shows a graph of Comparative Example 5. Referring to FIG 7, the average value of the pixel value is 0.482 × ^{10 -2,} which is substantially the same as Example 1. Therefore, the highlight luminance ratio and RMS granularity of Example 1 and Comparative Example 5 are compared. The highlight luminance ratio of Example 1 is 93.9% and the RMS granularity is 8.5 × ^10-2 , whereas the highlight luminance ratio of Comparative Example 5 is 93.6% and the RMS granularity is 11. It was 0.0 × 10 ^-2. It was found that by using the structure A or B, the RMS granularity can be improved while maintaining the brightness of the printed image guaranteed by the high highlight luminance ratio.

In inkjet printing, the dots generated when the ejected ink lands may cause a grainy feeling, which may impair the texture of the image. In particular, when printing cosmetics or high-class jewelry that frequently use human skin, the graininess of the dots impairs the texture of the subject, especially human skin. Conventionally, in order to improve the graininess, that is, the graininess, there is a method of lowering the transmittance of the printing sheet to make the dots difficult to see, but this method lacks the highlight brightness and lowers the overall image quality. There was a risk that it would end up. As in one embodiment of the present invention, the hiding ratio of the diffusion layer provided on the light source side is optimized, and a multi-layer structure is provided in which a resin layer is provided between the diffusion layer and the ink layer without sandwiching a gas layer or air bubbles. As a result, it was possible to obtain excellent overall image quality in characteristics such as graininess, highlight brightness, and shadow brightness, which could not be realized in the past.

The adjacent base material layers may be adhered with an adhesive instead of the double-sided acrylic pressure-sensitive adhesive sheet, and a method of preventing gas from entering between the base material layers without using a double-sided acrylic pressure-sensitive adhesive sheet or an adhesive. May be adhered with. Further, the diffusion layer and / or the ink receiving layer may be brought into close contact with the base material layer by a method such that gas does not enter between the pressure-sensitive adhesive sheet, the adhesive, and other layers. The number of base material layers is not limited to one or two, and may be three or more.

Comparing with Comparative Example 11 Example 8, a highlight luminance ratio 80.2 percent Example 8, a shadow luminance ratio 0.051%, for RMS granularity is 8.1 × ^{10 -2} against, the highlight luminance ratio 80.0% Comparative example 11, a shadow luminance ratio 0.152%, RMS granularity was 8.6 × ^{10 -2.} Thus, according to Example 8, to maintain a highlight luminance ratio more than 75%, and while maintaining the RMS granularity to 9.0 × ^{10 -2} or less, 0.065% or less of the shadow intensity ratio It was found that the contrast of the image can be improved as a low value of.

Comparing with Comparative Example 12 Example 9, a highlight luminance ratio 76.9% of that in Example 9, the shadow intensity ratio 0.021% to RMS granularity is 8.2 × ^{10 -2} against, the highlight luminance ratio of Comparative example 12 77.7% shadow luminance ratio 0.076% RMS granularity was 8.7 × ^{10 -2.} Thus, according to Example 9, to maintain a high light intensity ratio at or above 75% and keeping the RMS granularity to 9.0 × ^{10 -2} or less, 0.065% or less of the shadow intensity ratio It was found that the contrast of the image can be improved as a low value of.

Comparing with Comparative Example 13 and Example 10, a highlight luminance ratio 84.7 Example 10, the shadow intensity ratio 0.055% to RMS granularity is 8.0 × ^{10 -2} against, the highlight luminance ratio of Comparative example 13 83.9% shadow luminance ratio 0.139% RMS granularity was 8.6 × ^{10 -2.} Thus, according to Example 10, maintaining a highlight luminance ratio more than 75%, and while maintaining the RMS granularity to 9.0 × ^{10 -2} or less, 0.065% or less of the shadow intensity ratio It was found that the contrast of the image can be improved as a low value of.

The comparison between Examples 8 to 10 and Comparative Examples 11 to 13 will be described. Conventionally, there has been known a method of suppressing blocking of printed matter by roughening the surface of an ink receiving layer to make it uneven. When printing is performed on an uneven surface by an inkjet method, pinholes tend to occur in the ink layer. When a light source is installed on the back side of the printed matter, light is transmitted through the pinholes. Therefore, if the total area of the pinholes is large, the shadow luminance ratio does not decrease in the black part of the printed matter and the contrast of the printed matter decreases. There is a problem of doing. Therefore, it is necessary to reduce the number and size of pinholes. Referring to FIG. 8 as an example, Example 9 has a smaller total area of pinholes than Comparative Example 12. As a result, the transmitted light leaking from the pinhole can be reduced, and the shadow luminance ratio can be significantly improved while maintaining the highlight luminance ratio and the RMS granularity. As described above, according to one embodiment of the present invention, the number and size of pinholes in the ink layer are suppressed, thereby significantly improving the shadow luminance ratio while maintaining the highlight luminance ratio and RMS granularity. I found that I could do it. Furthermore, by setting the arithmetic average roughness Ra of the surface of the ink receiving layer to 0.3 μm or more, blocking of printed matter can be suppressed, and by setting it to 2.0 μm or less, the surface roughness, that is, the unevenness of the surface can be seen by the viewer. Can be difficult to see.

Note that the size, shape, and quantity of each member shown in the present specification and the drawings are examples, and are not limited thereto. Further, the material of each member is an example and is not limited thereto.

Although embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art will appreciate that the modifications are made in relation to the structure of each part without departing from the scope and spirit of the described invention. It is self-evident to.

10 Printed matter 11 Diffusing layer 12 Base material layer 13 Ink receiving layer 14 Ink layer 19 Printing sheet 20 Printed matter 50 LED surface light source

Claims

A base layer with light transmission and
An ink receiving layer provided on the surface of the base material layer and
A diffusion layer provided on the back surface of the base material layer is provided.
The diffusion layer is a printing sheet having a concealment rate of 60% or more and 94% or less.
The printing sheet according to claim 1, wherein the diffusion layer is adhered to the back surface of the base material layer.
The printing sheet according to claim 1 or 2, wherein the base material layers are plural, and each base material layer is in close contact with an adjacent base material layer.
The printing sheet according to any one of claims 1 to 3, wherein the base material layer is in close contact with the adjacent base material layer using an adhesive sheet.
The printing sheet according to any one of claims 1 to 4, wherein the diffusion layer has a concealment rate of 70% or more and 92% or less.
The printing sheet according to any one of claims 1 to 5, wherein the diffusion layer has a concealment rate of 72% or more and 88% or less.
The diffusion layer and the base material layer adjacent to the diffusion layer are in close contact with each other to form a diffusion sheet, and the haze value of the diffusion sheet is 70% or more and less than 100% according to any one of claims 1 to 6. The printed sheet of description.
Any one of claims 1 to 7, wherein the diffusion layer and a base material layer adjacent to the diffusion layer are in close contact with each other to form a diffusion sheet, and the total transmittance of the diffusion sheet is 45% or more and 100% or less. The printing sheet described in.
The printing sheet according to any one of claims 1 to 8, which has a thickness of 80 μm or more and 300 μm or less.
The printing sheet according to any one of claims 1 to 9, wherein the arithmetic average roughness Ra of the surface of the ink receiving layer is 0.3 μm or more and 2.0 μm or less.
It is provided with a light-transmitting base material layer, an ink receiving layer provided on the surface of the base material layer, and a diffusion layer provided on the back surface of the base material layer, and the diffusion layer is 60% or more and 94% or less. A printing sheet with a concealment rate,
A printed matter including an ink layer provided on the ink receiving layer.
The printed matter according to claim 11, wherein the highlight luminance ratio is 75% or more, the RMS granularity is 9.0 × 10-2 or less, and the shadow luminance ratio is 0.065% or less.
The printed matter according to claim 11 or 12, wherein the arithmetic average roughness Ra of the ink receiving layer is 0.3 μm or more and 2.0 μm or less.