WO2010079765A1 - Recording sheet and illuminated sign board - Google Patents

Abstract

Provided are a recording sheet which can provide an image of a natural tone with a reduced pale blue and an illuminated sign board, using the same, in the field of an illuminated sign board using a white LED as a light source.  A recording sheet used for an illuminated sign board comprises a sheet substrate (11) on one surface of which an under layer (12) and an image recording layer (13) are formed in this order.  Light emitted from a white LED is transmitted successively through the substrate (11), the under layer (12), and the image recording layer (13).  The substrate (11) has a yellow index of 5 to 13 when viewed from the under layer (12) side, when the under layer (11) is provided on the substrate but the image recording layer (13) is not provided thereon.

Description

Recording sheet and signboard

The present invention relates to a recording sheet suitably used for an electric signboard and an electric signboard using the same. More specifically, the present invention relates to a recording sheet that can provide an image having a natural color tone that is not bluish even when used in an electric signboard using a white light emitting diode (hereinafter referred to as “white LED”) as a light source, and It is related with the electric signboard using.

Conventionally, there is an electric signboard provided with a sheet having an image and a light source, and the electric signboard is used for various advertisements, signs, maps, and the like.
Examples of the sheet having an image include a sheet printed by various printers, a sheet printed by a printing machine such as an offset printing machine, and a sheet to which a cutting sheet is attached. Among them, those printed by printers of various recording systems such as an ink jet recording system, a thermal transfer system, and an electrophotographic system are frequently used because they can easily cope with a small lot and a short delivery time.
Conventionally, fluorescent lamps have often been used as light sources for electric signboards. However, in recent years, white LED light sources have been used for the purpose of extending the life of light sources and reducing power consumption (Patent Document 1).
In addition, white LED here obtains white light using LED.

Using a white LED has the above-mentioned advantages, but has a problem that the color becomes paler than that of a fluorescent lamp. Depending on the application, the paler color may be suitable for giving a sharp impression, but it may not be suitable because it gives an impression that the color is not natural and is cold. This tendency is particularly strong when full-color photographic images are used. In addition, when the image software is adjusted assuming a conventional fluorescent lamp device, the user may be used to the fluorescent lamp and feel uncomfortable with the color tone of the white LED. There is a need for an electric signboard having the same color tone as a lamp.

In a display device having a light source in the background, a method using a color correction filter has been proposed as a method of correcting the color (Patent Document 2). This is mainly used for the liquid crystal display of a notebook personal computer, and is a technique that can be applied to an electric signboard, although the required color is different from that of an electric signboard.
However, if the method of reducing the paleness by installing a filter on the signboard itself is not available to users who have already purchased the signboard, it is not suitable when using images with designs that require blue and white. When using image software that suppresses bluishness assuming an LED, there are problems such as excessive suppression and expensive equipment. Therefore, it is required to correct by the sheet on which the image is recorded.

There is a technique for correcting the appearance by improving the recording sheet for use as an electric signboard (Patent Document 3). In the recording sheet proposed in Patent Document 3, a primer layer containing a colorant is provided between the base sheet and the ink receiving layer. The colorant contained is a white pigment or dye. The purpose is to make the unevenness of the substrate and the coating unevenness of the ink receiving layer inconspicuous by adjusting the total light transmittance of the recording sheet and the total light transmittance of the primer layer, It does not improve the unnatural color caused by the light source used. Conventionally, there has been no method for solving the bluishness of the tint by improving the recording sheet in the electric LED signboard of the white LED light source (Patent Document 1, Patent Document 4, Patent Document 5).

JP 2006-202729 A JP 2004-117542 A Japanese Patent No. 4001017 JP 2006-202725 A JP 2008-250067 A

An object of the present invention is to provide a recording sheet capable of providing an image of a natural color tone with suppressed bluish white and an electric signboard using the same in the field of electric signboards of white LED light sources. It is.

The recording sheet of the present invention, which has been made for the purpose of solving the above problems, comprises an undercoat layer and an image recording layer sequentially provided on one surface of a sheet-like substrate, and the light from the white LED A recording sheet for use in an electric signboard that sequentially transmits through a base material, the undercoat layer, and the image recording layer, wherein the undercoat layer is provided on the base material and the image recording layer is not provided. It is characterized in that the yellowness viewed from the drawing layer side is 5 to 13.

In this invention, the yellowness can be adjusted to 5 to 13 by adding a colorant to the undercoat layer. In the present invention, the total light transmittance in a state in which the undercoat layer and the image recording layer are sequentially provided on the substrate can be set to 20% to 50%.

In the present invention, the image recording layer can be an ink receiving layer of an ink jet recording sheet, an ink receiving layer of a thermal transfer recording sheet, or a toner fixing layer of a recording material used in an electrophotographic recording system. Furthermore, the recording sheet of the present invention can be applied to a substrate to be used for printing using a plate.

In addition, the electric signboard of the present invention made for the purpose of solving the above problems is a recording sheet in which an undercoat layer and an image recording layer are sequentially provided on one surface of a sheet-like base material, An electric signboard comprising a base material, the undercoat layer, and a white LED as a light source for irradiating light that sequentially passes through the image recording layer, wherein the image recording layer is provided with the undercoat layer on the base material The yellowness as viewed from the undercoat layer side is 5 to 13 in a state where no is provided.

In this invention, the yellowness can be adjusted to 5 to 13 by adding a colorant to the undercoat layer. In the present invention, the total light transmittance of the recording sheet can be 20% to 50%. In the present invention, the image recording layer can be an ink receiving layer of an ink jet recording sheet, an ink receiving layer of a thermal transfer recording sheet, or a toner fixing layer of a recording material used in an electrophotographic recording system. Furthermore, the recording sheet of the present invention can be applied to a substrate to be used for printing using a plate.

In the present invention, at least one of a light reflecting plate, a light diffusing plate, and a light diffusing reflecting plate is disposed on the light incident side of the recording sheet to suppress uneven irradiation of light irradiated to the recording sheet. Can be configured to. Further, in the present invention, a plurality of white LEDs can be arranged so as to suppress uneven irradiation of light irradiated on the recording sheet. Further, in the present invention, the front wall of the flat rectangular box-shaped signboard body is formed of a recording sheet, the white LEDs are respectively disposed on the inner surfaces of both side walls of the signboard body, and on the inner surface of the back wall of the signboard body, It is possible to arrange the reflector so as to suppress the irradiation unevenness of the light applied to the recording sheet.

According to the present invention, since the undercoat layer contains a colorant that makes the yellowness as viewed from the undercoat layer side when the undercoat layer alone is provided on the base material, bluish white is suppressed. Thus, a recording sheet and an electric signboard capable of providing a natural color image can be obtained.

It is sectional drawing of the sheet | seat for recording of one Embodiment which concerns on this invention. It is a partial cutaway perspective view of the electrical signboard of 1st Embodiment based on this invention which used the recording sheet shown in FIG. 1 as a display sheet. It is a partial cutaway perspective view of the electrical signboard of 2nd Embodiment based on this invention which used the recording sheet shown in FIG. 1 as a display sheet.

Hereinafter, an embodiment of a recording sheet according to the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the recording sheet 1 of the present embodiment includes a sheet-like base material 11 through which light from a white LED transmits, an undercoat layer 12 provided on one surface of the base material 11, And an image recording layer 13 provided on the undercoat layer 12, and used for an electric signboard in which light from a white LED sequentially passes through the substrate 11, the undercoat layer 12, and the image recording layer 13. is there.

First, the configuration of the base material 11 will be described. The base material 11 is not particularly limited as long as the base material 11 has a sheet-like shape having a degree of transparency that can be used for an electric signboard application. Plastic film, synthetic paper, paper, cloth, non-woven fabric and the like can be used.
Of these, a plastic film is preferable in terms of transparency, processability, strength, and the like. The plastic film is not particularly limited. Polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, soft polyvinyl chloride, hard polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, ethylene Examples include vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, and polyvinyl acetate.

Next, the undercoat layer 12 will be described. The undercoat layer 12 is a layer located between the base material 11 and the image recording layer 13. In general, in the recording sheet 1, it is difficult to achieve both the printing quality of the image recording layer 13 and the strength of adhesion to the substrate 11. This tendency is particularly strong when the substrate 11 is a plastic film and the image recording layer 13 is provided by coating. Therefore, the undercoat layer 12 is often provided for the purpose of enhancing adhesion. The undercoat layer 12 may be referred to as a primer layer, an undercoat layer, or an anchor coat layer. Further, the purpose is not limited to the enhancement of adhesion. For example, in the case of an ink jet recording sheet, there is a case where it contributes to the adjustment of the printing quality by assisting the absorption of the ink solvent.

The undercoat layer 12 contains a colorant in order to make it yellowish. As a method for making the recording sheet 1 yellowish, in addition to the method for coloring the undercoat layer 12 as in the present invention, a method for coloring the substrate 11 itself or the image recording layer 13, or a separate colored layer is provided. A method, a method of performing yellow printing on any layer by offset printing, gravure printing, or the like can be considered. However, there is a problem that the base material 11 generally has a large production lot. When the image recording layer 13 is colored, for example, when the illumination signboard light source is turned off and it is viewed with reflected light when it is bright in the daytime, the image recording layer 13 is strong in yellow color, so the whiteness is insufficient and the image is conspicuous There is no problem. In addition, a method of separately providing a colored layer or performing printing has a problem of increasing costs. Accordingly, as a method for making the recording sheet 1 yellowish, it is preferable to color the undercoat layer 12 in the present invention, but it is not limited to coloring the undercoat layer 12.

As the colorant to be contained in the undercoat layer 12, yellow colorants such as yellow pigments and yellow dyes can be considered. Pigments are more preferred because they are less likely to fade than dyes.
The yellow pigment contained in the undercoat layer 12 is not particularly limited, and various known pigments can be used. For example, C.I. I. Pigment yellow 12, 13, 14, 17, 55, 81, 83, 136 and the like, disazo yellow pigments such as C.I. I. Monoazo yellow pigments such as CI Pigment Yellow 1, 3, 65, 73, 74, 75, 116, 151, 154, and 181; I. Azo lake yellow pigments such as C.I. Pigment Yellow 183, C.I. I. Condensed yellow pigments such as CI Pigment Yellow 93 and 95, C.I. I. Pigment Yellow 109 and 110, isoindolinone yellow pigments such as C.I. I. Isoindoline-based yellow pigments such as CI Pigment Yellow 139; I. And condensed polycyclic yellow pigments such as CI Pigment Yellow 24 and 108.
The yellow dye contained in the undercoat layer 12 is not particularly limited, and various known dyes can be used. Examples thereof include azo dyes, anthraquinone dyes, condensed polycyclic aromatic carbonyl dyes, indigoid dyes, polymethine dyes, and the like.
In order to adjust the yellowness viewed from the undercoat layer 12 side to a range of 5 to 13, in the present invention, the undercoat layer 12 preferably contains a yellow colorant, but is not limited thereto. Alternatively, the yellowness may be adjusted by containing a yellow colorant and a colorant other than yellow, or a colorant other than yellow.

The undercoat layer 12 contains a binder and a filler as components other than the colorant, and can further contain various additives. Examples of the binder include starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol and derivatives thereof, polyvinyl pyrrolidone, casein, gelatin, soybean protein, styrene-acrylic resin and derivatives thereof. Styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, alkyd emulsion, and derivatives thereof.

By adding a filler, effects such as adjustment of ink absorption speed, prevention of blocking during coating, and adjustment of transparency of the recording sheet 1 can be obtained. Examples of the filler include inorganic fillers such as calcium carbonate, silica, titanium oxide, and kaolin, and various plastic pigments.

Further, the undercoat layer 12 may have an antifoaming agent, an antistatic agent, an ultraviolet absorber, a fluorescent whitening agent, a preservative, a pigment dispersant, a thickening agent as long as the effects of the present invention are not impaired. Etc. may be added.

The color of the recording sheet 1 of the present invention can be adjusted by adjusting the type and amount of the yellow colorant in the undercoat layer 12. In the present invention, the yellowness of the recording sheet 1 is defined. The yellowness of the recording sheet 1 in the present invention is a state in which only the undercoat layer 12 is provided on the substrate 11 and the image recording layer 13 is not provided. The yellowness as viewed from the undercoat layer 12 side is adjusted. In the recording sheet 1 of the present invention, the yellowness is adjusted to a range of 5 to 13. Yellowness here is based on JIS K7105, and is calculated by the following formula by measuring XYZ by the transmission method.
Yellowness = 100 × (1.28 × X−1.06 × Z) / Y
However, X, Y, and Z are tristimulus values of the XYZ color system in a C light source (a kind of standard light defined by the International Commission on Illumination (abbreviated as CIE)). Hereinafter, “the yellowness viewed from the undercoat layer 12 side in the state where only the undercoat layer 12 is provided on the base material 11 and the image recording layer 13 is not provided” is “as seen from the undercoat layer 12 side”. It may be expressed as “yellowness”.

The reason why the above range is preferable is as follows. That is, the color of the recording sheet 1 when viewed as an electric signboard and the color of the image recorded or printed there can be adjusted by the color of the undercoat layer 12. However, it is also affected by the total light transmittance in the state in which the entire recording sheet 1, that is, the base material 11, the undercoat layer 12, and the image recording layer 13 are all provided. Here, the total light transmittance is based on JIS K7105.

When the total light transmittance of the entire recording sheet 1 is low, the bluish light of the LED is obstructed, so that the bluish color is not so strong and the yellow color of the undercoat layer 12 is adjusted to be weak. preferable. On the other hand, when the total light transmittance is high, the bluish light of the white LED is easily transmitted. Therefore, it is preferable to adjust the yellow color of the undercoat layer 12 so that the bluish color is stronger.
On the other hand, in the case of use as an electric signboard, according to the study of the present inventors, the preferable range of the total light transmittance is 20% to 50%. If it is less than 20%, the overall impression may be too dark, and if it exceeds 50%, the image may be too bright and the image may not be noticeable.

When the total light transmittance of the recording sheet 1 is 20%, which is the lower limit of the preferred range, the yellowness viewed from the undercoat layer 12 side is less than 13, and the recording sheet 1 is mounted on the apparatus and viewed as an electric signboard. The color of the case is natural and suitable. If it exceeds 13, there may be an impression that the yellow color is too strong when it is attached to the apparatus and viewed as an electric signboard.

Further, when the total light transmittance of the recording sheet 1 is 50% which is the upper limit of the preferable range, when the yellowness viewed from the undercoat layer 12 side is 5 or more, the recording sheet 1 is attached to the apparatus as an electric signboard. The color when seen is natural and good. If it is less than 5, there may be an impression that the blue color is too strong when it is attached to the apparatus and viewed as an electric signboard. The more preferable total light transmittance of the entire recording sheet 1 is 30% to 40% from the viewpoint that more natural brightness can be obtained. In this case, the more preferable undercoat layer 12 is obtained from the point that a natural color can be obtained. The yellowness as viewed from the side is 7-10.

Here, regarding the color on the image recording layer side when light from the white LED light source is irradiated from the substrate side of the recording sheet, including the image to be appreciated, the yellowness and the total light transmittance of the recording sheet In this relation, a preferable range is shown in Table 1 below.

The content ratio of the yellow colorant in the undercoat layer 12 may be adjusted as appropriate according to the intended use, but it is easy to adjust the yellowness viewed from the undercoat layer 12 side to the preferred range. The solid content is preferably 0.001 to 0.1% with respect to the pulling layer 12. More preferably, it is 0.01 to 0.05%.

The thickness of the undercoat layer 12 is preferably 1 to 20 μm from the viewpoint of adhesion strength between the image recording layer 13 and the substrate 11.
Further, the method for forming the undercoat layer 12 is not particularly limited, and a known method can be used. Gravure coat, gravure reverse coat, gravure offset coat, blade coat, spinner coat, roll coat, reverse roll coat, An air knife coat, a kiss coat, a dip coat, a silk screen coat, a wire bar coat, a comma coat, a spray coat, a float coat, a pouring coat, etc. can be used.

Next, the image recording layer 13 will be described. As the image recording layer 13, a layer suitable for the intended printing method can be formed by a known method.
For example, when the recording sheet 1 is an ink jet recording sheet, it can be formed by various known fillers, binders, cationizing agents and other additives. Note that the image recording layer 13 in the case of an ink jet recording sheet may be referred to as an ink receiving layer or an ink receiving layer.

As the filler used for the image recording layer 13 of the ink jet recording sheet, a known inorganic or organic filler can be used. For example, silica, calcium carbonate, talc, clay, diatomaceous earth, titanium oxide, calcined kaolin, hydroxylated Aluminum, polystyrene, polymethacrylate, etc. are mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of the binder include polyvinyl alcohol, polyvinyl butyral, gelatin, polyvinyl acetal, carboxymethyl cellulose, polyvinyl pyrrolidone, polyester resin, acrylic resin, polyurethane resin, copolymers thereof, styrene-acrylic copolymers, ethylene -Vinyl acetate copolymer, styrene-butadiene rubber and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types.

As the additive, it is preferable to use a cationic substance for the purpose of improving the blurring performance and color development of the image. It can be selected from those known in the field of inkjet recording sheets. For example, it is preferably a polymer having a quaternary ammonium base, and particularly preferably a homopolymer of a monomer having a quaternary ammonium base or a copolymer with one or more other copolymerizable monomers. . Examples of cationic polymers having a quaternary ammonium base include dimethyldiallylammonium chloride, polyamine sulfones, (meth) acrylic acid alkyl quaternary ammonium salts or (meth) acrylamide alkyl quaternary ammonium salt type cationic polymers. , A copolymer of dimethylallylammonium chloride and acrylamide, and a cationic polymer obtained by a reaction of a secondary amine and epihalohydrin.

Further, as an additive, in addition to the above-mentioned cationic substance, an aluminum compound such as aluminum lactate or aluminum sulfate may be contained for the purpose of improving the water resistance of the image recording layer 13. Furthermore, various additives such as a surfactant, an ultraviolet absorber and an antifungal agent can be used depending on the purpose.

The ratio of the filler to the binder in the case of the ink jet recording sheet is such that the filler is 1 to 6 when the binder is 1 in terms of the solid mass ratio in order to achieve both ink absorbability and layer strength. A range is preferable. More preferably, it is 2-4.

The method for forming the image recording layer 13 is not particularly limited, and a method similar to the method for forming the undercoat layer 12 can be used.

The present invention can be applied to various known recording sheets in addition to the inkjet recording sheet. For example, in the case of a thermal transfer image-receiving sheet, as described in Japanese Patent No. 411594, it has an ink-receiving layer containing a pigment having a predetermined oil absorption amount and a surfactant having water retention property on at least one surface of a substrate. In this recording sheet, by providing an undercoat layer containing a yellow colorant between the substrate and the ink receiving layer, the recording sheet can be used as a recording sheet for an electric signboard. In addition, a sheet to be printed by an electrophotographic method is described in, for example, Japanese Patent Application Laid-Open No. 2006-276841. In that case, an electrophotographic film in which a toner fixing layer containing tin oxide is provided on at least one surface of a plastic film. In the recording material for recording, by providing an undercoat layer containing a yellow colorant between the plastic film and the toner fixing layer, it can be used as a recording sheet for an electric signboard.

Further, the present invention relates to a printing medium used for printing using a plate, specifically, offset printing for printing after the ink attached to the plate is once transferred to an intermediate transfer body such as a rubber blanket, The present invention can also be applied to a substrate to be used for gravure printing in which a portion to which ink is attached is engraved. In that case, the substrate (recording sheet) needs to have a three-layer configuration of a base material, an undercoat layer containing a yellow colorant, and an image recording layer.

Accordingly, the recording sheet 1 of the present embodiment is a colorant that makes the undercoat layer 12 have a yellowness of 5 to 13 when viewed from the undercoat layer 12 side when only the undercoat layer 12 is provided on the base material 11. Therefore, it is possible to provide an image having a natural color tone with suppressed bluish white.

Next, the electrical signboard according to the present invention will be described. The electric signboard according to the present invention is formed by mounting the recording sheet 1 according to the present invention on a device for an electric signboard of a white LED light source.
Conventionally, various types of electric signboards have been used, such as a large outdoor sign such as a signboard of a bank store and a small one placed on a counter in a store. Since the apparatus has a light source, the viewer sees the light emitted from the light source on the back of the image. In other words, the image is viewed with transmitted light.
Conventionally, a fluorescent lamp is generally used as the light source, but in recent years, the use of a white LED has increased. The present invention corresponds to this.
An image is generally formed by printing on a recording sheet 1 by various recording methods. The printed recording sheet 1 is used by being attached to a transparent plate such as an acrylic plate or by being attached by insertion.

Hereinafter, the electrical signboard A of the first embodiment and the electrical signboard B of the second embodiment using the recording sheet 1 according to the present invention as a display sheet will be described with reference to FIGS. The electric signboard according to the present invention is not limited to the electric signboard of the first embodiment and the electric signboard of the second embodiment illustrated in FIGS.

The electrical decoration signboard A of 1st Embodiment is provided with the signboard main body formed in flat rectangular box shape, as shown in FIG. A display sheet H is used as a front wall of the signboard body. The display sheet H is configured by adhering the light emission side surface of the recording sheet 1 on which the image is applied to the image recording layer 13 to the acrylic plate 2, and the acrylic plate 2 is disposed on the inner wall surface. ing. The base 3 that is the back wall of the signboard main body is disposed on the back side of the display sheet H with an appropriate gap. A white LED 4 as a light source is disposed on the inner surface of the substrate 3. A plurality of white LEDs 4 are preferably arranged so as to suppress uneven irradiation of the light applied to the recording sheet 1. For example, in the illustrated example, the white LEDs 4 are equally spaced in the vertical direction (height direction) and are A plurality are arranged at equal intervals in the direction (width direction).

Between the base 3 and the display sheet H, a light reflecting plate 5 and a light diffusing reflecting plate 6 are disposed. For example, the light reflecting plate 5 is arranged in front of the base 3 with an interval of about 1 mm to several mm. The light reflecting plate 5 is formed with a plurality of holes into which the white LEDs 4 can be loosely fitted. The light diffusing reflector 6 has a plurality of small holes formed on the entire surface. As described above, by providing the white LED 4, the light reflection plate 5, and the light diffusion reflection plate 6, the light emitted from the white LED 4 goes straight and is reflected by the reflection surface on the front surface of the light reflection plate 5 to diffuse the light. Irradiation unevenness of light transmitted through a small hole of the light diffusing reflection plate 6 and irradiating the back surface of the display sheet H while being repeatedly reflected with the reflection surface on the back surface of the reflection plate 6 is suppressed. . As a result, unevenness of the light transmitted through the image recording layer 13 of the recording sheet 1 was suppressed, and the image was printed on the image recording layer 13 with a natural color tone with the bluish white suppressed by the undercoat layer 12. The image 7 is also very easy to see and beautiful.

In addition, in the electrical decoration signboard A of 1st Embodiment, although the light reflection board 5 and the light-diffusion reflection board 6 were provided and the irradiation unevenness of the light irradiated to the display sheet H was suppressed, it is limited to this. Instead, at least one of a light reflecting plate, a light diffusing plate, and a light diffusing reflecting plate may be provided as long as uneven irradiation of the light irradiated to the display sheet H can be suppressed. For example, in the electric signboard of the first embodiment, a light diffusing plate (not shown) whose back surface is not a reflecting surface may be used instead of the light diffusing reflecting plate 6, or the light reflecting plate 5 is provided. Alternatively, only the light diffusing reflector 6 may be provided, or only the light reflector 5 may be provided without providing the light diffusing reflector 6. Moreover, you may make it irradiate directly the back surface of the display sheet H only by white LED4, without providing both the light reflection board 5 and the light-diffusion reflection board 6. FIG. In addition, when the back surface of the display sheet H is directly irradiated with only the white LEDs 4, a plurality of white LEDs 4 may be arranged side by side so as to draw characters and symbols on the substrate 3. In this case, the surface of the display sheet H is white. Characters and symbols by the light emitted from the LED 4 are displayed so as to emerge. The acrylic sheet of the display sheet H can be transparent, translucent, or appropriately colored. In addition to acrylic plates, thin plastic plates such as polystyrene, polypropylene, and polycarbonate can also be used.

As shown in FIG. 3, the electric signboard B of the second embodiment uses a display sheet H on the front wall of a flat rectangular box-shaped signboard main body, similar to the electric signboard A of the first embodiment described above. It will be. This electric signboard B is configured by arranging a plurality of white LEDs 8 on the left and right side walls, that is, the inner surfaces of both side walls, without providing LEDs on the base 3. For example, in the illustrated example of the longitudinal direction of the side wall, the white LED 8 has a plurality of white LEDs 8 arranged in the vertical direction (height direction) at an appropriate interval, and the white LED 8 is appropriately spaced in the width direction of the side wall (the thickness direction of the electric signboard B). Opened and arranged in two rows. A light reflecting plate 9 is disposed on the inner surface of the base 3. The light reflecting plate 9 has a surface facing the display sheet H formed as a light reflecting surface 9 ′, and this light reflecting surface 9 ′ suppresses uneven irradiation of light from the white LED 8 irradiated on the back surface of the display sheet H. It is formed to be. The light reflecting surface 9 ′ is not particularly limited as long as uneven irradiation of light can be suppressed. For example, the light reflecting surface 9 ′ is formed in a curved cross section in which the central portion in the width direction of the electric signboard B is projected to the display sheet H side. A plurality of curved surfaces may be formed in the width direction at appropriate intervals. Thus, by providing the light reflecting plate 9, a part of the irradiation light from the white LED 8 is directly irradiated to the back side of the display sheet H, but most of the light is reflected by a plurality of curved surfaces of the light reflecting surface 9 '. Then, light irregularly reflects within the electric signboard B, and uneven irradiation of light irradiated on the back surface of the display sheet H is suppressed. As a result, unevenness of the light transmitted through the image recording layer 13 of the recording sheet 1 was suppressed, and the image was printed on the image recording layer 13 with a natural color tone with the bluish white suppressed by the undercoat layer 12. The image 7 is also very easy to see and beautiful. In addition, the illumination signboard B may also be provided with a light diffusing reflector so as to suppress light irradiation unevenness.

Therefore, since the electrical signboard of this embodiment becomes an electrical signboard with a natural color that is not too strong even if white LEDs are used as a light source, the image of a person, particularly a fresh food image on a cosmetic signage. It is even more effective when used for the above.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the mass part in an Example and a comparative example shall show solid content.

〔Evaluation methods〕
Various evaluation methods are as follows.
・ Yellowness (YI value)
Based on JIS K7105, XYZ was measured by the transmission method using a color matching system (model name: Toning Senka TX) manufactured by Nisshinbo Industries, Ltd., and a YI value was calculated by the following formula.
YI value = 100 × (1.28 × X−1.06 × Z) / Y
However, X, Y, and Z are tristimulus values of the XYZ color system in the C light source.
-Total light transmittance Based on JIS K7105, it measured using the haze meter (model name: direct reading haze meter) by Toyo Seiki Seisakusho.
・ Color of sheet when LED is lit (correlated color temperature K)
Each of the obtained ink jet recording sheets is attached to a device for an electric signboard manufactured by Aristo Japan Co., Ltd. (trade name: LED raster board, high brightness product with white LED as light source, illuminance 2500 lx), and lighted. The measurement was carried out using a color illuminometer (model name: CL-200) manufactured by Konica Minolta Sensing Co., Ltd. from directly above 10 mm.
A: Good balance between blue and yellow (good correlation color temperature of 5500 or more and less than 7500)
○: A level that can be said to be suitable although it has a lot of blueness (correlated color temperature of 7500 or more and less than 8000)
○: Level that can be said to be suitable although it has a lot of yellowishness (correlated color temperature of 5000 or more and less than 5500)
X: Strong blue (correlated color temperature of 8000 or more)
X: Strong yellowish (correlated color temperature less than 5000)

[Example 1]
As a base material, a polyester film having a thickness of 100 μm (trade name: Cosmo Shine A8300, manufactured by Toyobo Co., Ltd.) was used. On one side of the base material, the thickness after drying the following undercoat layer coating liquid was 10 μm. After coating and drying, the following ink-receiving layer (image recording layer) coating solution is applied onto the undercoat layer so that the thickness after drying is 25 μm and dried. Thus, an ink receiving layer was provided to prepare an ink jet recording sheet.
The YI value of the surface of the undercoat layer after formation of the undercoat layer (before formation of the ink receiving layer) was 9.2, and the total light transmittance after formation of the ink receiving layer was 38.8%.
[Coating liquid for undercoat layer: homogeneous mixture of the following components]
(A) Filler / calcium carbonate [Shiraishi Kogyo Co., Ltd., trade name: Callite SA, solid content concentration: 100% by mass] 11.00 parts by mass (b) Binder / acrylic resin (styrene-acrylic copolymer) ) [BASF Dispersion Co., Ltd., trade name: Acronal YJ6221D, solid content concentration 49% by mass] 54.00 parts by weight, polyester [Toyobo Co., Ltd., trade name: Vironal MD1200, solid content concentration 35% by mass ] 20.00 parts by mass (c) yellow pigment [manufactured by Sanyo Color Co., Ltd., trade name: EMACOL NS YELLOW 4618, solid content concentration 25% by mass] 0.06 parts by mass (d) 15.0 parts by mass of water [ink Receiving layer coating solution: Uniform mixture of the following components]
(A) Filler / Silica [Fuji Silysia Chemical Co., Ltd., trade name: Silicia 420, solid content concentration 100% by mass] 11.00 parts by mass (b) Binder / Silanol-modified polyvinyl alcohol [manufactured by Kuraray Co., Ltd. , Trade name: Kuraray R polymer R-1130, solid content concentration 100% by mass] 3.80 parts by mass (c) additive / antifoaming agent (manufactured by San Nopco Co., Ltd., trade name: SN deformer 480, solid content concentration 100) 0.10 parts by mass / hydrated aluminum oxide [manufactured by Nissan Chemical Industries, Ltd., trade name: alumina sol 200, solid content concentration 10% by mass] 7.00 parts by mass / cationic polymer [Taoka Chemical Industries Product name: Sumires 1001, solid concentration 30% by mass] 2.50 parts by mass (d) 75.60 parts by mass of water

[Example 2]
The coating liquid for the undercoat layer in Example 1 was the same as Example 1 except that the yellow pigment [EMACOL NS YELLOW 4618] was 0.02 parts by mass, and the thickness of the ink receiving layer after drying was changed to 20 μm. Thus, an inkjet recording sheet was prepared.
The YI value after forming the undercoat layer was 5.4, and the total light transmittance after forming the ink receiving layer was 48.5%.

Example 3
As the coating liquid for the undercoat layer in Example 1, the yellow pigment [EMACOL NS YELLOW 4618] was changed to 0.07 part by mass, and the thickness after drying of the ink receiving layer was changed to 60 μm. Thus, an inkjet recording sheet was prepared.
The YI value after forming the undercoat layer was 12.5, and the total light transmittance after forming the ink receiving layer was 21.0%.

[Comparative Example 1]
An inkjet recording sheet was prepared in the same manner as in Example 1 except that the undercoat layer coating solution in Example 1 did not contain a yellow pigment [EMACOL NS YELLOW 4618].
The YI value after forming the undercoat layer was 3.1, and the total light transmittance after forming the ink receiving layer was 39.7%.

Table 2 shows the results of performance evaluation for each of the inkjet recording sheets obtained in Examples 1 to 3 and Comparative Example 1.

Moreover, as a result of visual judgment, Example 1 had a moderate brightness and a very good balance between blue and yellow.
Although Example 2 was brighter and more bluish than Example 1, it was a suitable level.
Although Example 3 was darker and more yellowish than Example 1, it was a suitable level.
In Comparative Example 1, the brightness was moderate and excellent, but the level of blueness was too high to be suitable for advertising.

According to the present invention, it is possible to provide a recording sheet that becomes an electric signboard with a natural tint that is not too bluish when mounted on a device using a white LED as a light source, and is capable of providing energy saving and excellent images. It is possible to provide an electric signboard that is compatible.

1 Recording sheet
11 Substrate
12 Underlayer
13 Image recording layer 2 Acrylic plate 3 Base 4 and 8 White LED
5 Light Reflector 6 Light Diffuse Reflector 7 Image, Character, etc. 9 Light Reflector A, B Electric Decoration Sign H Display Sheet

Claims (13)

An electric signboard in which an undercoat layer and an image recording layer are sequentially provided on one surface of a sheet-like base material, and light from a white LED is sequentially transmitted through the base material, the undercoat layer, and the image recording layer. A recording sheet used for
A recording sheet having a yellowness of 5 to 13 as viewed from the undercoat layer side in a state where the undercoat layer is provided on the base material and the image recording layer is not provided. The recording sheet according to claim 1, wherein the yellowness is adjusted to 5 to 13 by adding a colorant to the undercoat layer. The recording sheet according to claim 1 or 2, wherein the total light transmittance is 20% to 50% in a state where the undercoat layer and the image recording layer are sequentially provided on the substrate. The image recording layer is an ink receiving layer of an ink jet recording sheet, an ink receiving layer of a thermal transfer recording sheet, or a toner fixing layer of a recording material used in an electrophotographic recording system. The recording sheet according to Item. The recording sheet according to any one of claims 1 to 3, wherein the recording sheet is a substrate to be used for printing using a plate. A recording sheet in which an undercoat layer and an image recording layer are sequentially provided on one surface of a sheet-like substrate, and a light source that emits light that sequentially passes through the substrate, the undercoat layer, and the image recording layer An electric signboard equipped with a white LED,
An electrical signboard characterized by having a yellowness of 5 to 13 as viewed from the undercoat layer side in a state where the undercoat layer is provided on the substrate and the image recording layer is not provided. The recording sheet according to claim 6, wherein the yellowness is adjusted to 5 to 13 by adding a colorant to the undercoat layer. The electric signboard according to claim 6 or 7, wherein the total light transmittance of the recording sheet is 20% to 50%. The image recording layer is an ink receiving layer of an ink jet recording sheet, an ink receiving layer of a thermal transfer recording sheet, or a toner fixing layer of a recording material used in an electrophotographic recording system. The electric signboard according to the item. The electric signboard according to any one of claims 6 to 8, wherein the recording sheet is a printed material used for printing using a plate. At least one of a light reflecting plate, a light diffusing plate, and a light diffusing reflecting plate is disposed on the light incident side of the recording sheet so as to suppress uneven irradiation of light irradiated on the recording sheet. The electric signboard according to any one of claims 6 to 10. The electric signboard according to any one of claims 6 to 11, wherein a plurality of the white LEDs are arranged so as to suppress uneven irradiation of light irradiated on the recording sheet. A front wall of a flat rectangular box-shaped signboard body is formed of the recording sheet, the white LEDs are respectively arranged on the inner surfaces of both side walls of the signboard body, and a reflector is disposed on the inner surface of the back wall of the signboard body. The electric signboard according to any one of claims 6 to 12, wherein the signboard is arranged so as to suppress irradiation unevenness of light applied to the recording sheet.

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