EP1031432A1

EP1031432A1 - Recording sheet having phosphorescence and sign

Info

Publication number: EP1031432A1
Application number: EP99918305A
Authority: EP
Inventors: Shigeru Somar Corporation MASHIMA; Torao Somar Corporation HAYASHI; Nozomi Somar Corporation NAGASE
Original assignee: Somar Corp
Current assignee: Somar Corp
Priority date: 1998-09-04
Filing date: 1999-04-30
Publication date: 2000-08-30
Also published as: EP1031432A4; WO2000013910A1; JP2000141884A

Abstract

A recording sheet in which a luminous layer composed of a resin and a luminous pigment is formed on at least one of both surfaces of a substrate film and in which a recording layer which permits recording with a toner or an ink is provided on the luminous layer or on a surface opposite the luminous layer. Disclosed also is a display material having an image layer of a resolution of 200-1400 dpi provided on the luminous layer or on a surface opposite the luminous layer. As a result of the above constitution, there are provided a recording sheet or a display material which has excellent visibility and which is suitably used as an information plate or poster to be placed in the dark.

Description

Technical Field:

This invention relates to a luminous recording sheet having excellent visibility useful as information plates or posters to be placed in the dark and to a display material having luminous property.

Background Art:

As sheets having good visibility in the dark, (1) those obtained by shaping a resin (a polyvinyl chloride resin in particular) containing a retroreflective agent or a luminous pigment into a sheet-like form and (2) those obtained by forming an image on an ordinary sheet with an ink containing a luminous agent are known. Any of these sheets has visibility in the dark because the luminous agent can absorb light of sunlight or interior illumination and emit light by releasing the energy in the night or dark.

In the case of the sheet (1) above, however, since the luminous pigment is kneaded with a resin and since the kneaded resin is formed into films, the sheet is not fully satisfactory with respect to mechanical strengths, productivity and costs.

Since the sheet (2) above is not of a roll-type, the productivity is low. Further, it is necessary to apply coatings repeatedly in order to obtain a certain degree of luminance. Thus, there is a defect that the surface characteristics of the product sheets are not good and the productivity is low. Furthermore, it is necessary to adopt screen printing for the formation of the ink images. Thus, a screen printing plate must be prepared. It follows that this technique is not suited for production of various kinds of products each in a small amount.

It is an object of the present invention to provide a luminous recording sheet with which a luminous display material is easily prepared from written or image patterns formed with a personal computer and which does not require bonding of a luminous sheet and an output sheet, and to provide a display material.

Disclosure of the Invention:

The present inventors have made earnest studies to solve the above-described problems and have completed the present invention.

In accordance with the present invention, there is provided a recording sheet having luminous property, characterized in that a luminous layer comprising a resin and a luminous pigment is formed at least one of the both surfaces of a substrate film, and in that a recording layer which permits recording with a toner or an ink is provided on said luminous layer or on a surface opposite said luminous layer.

The present invention also provides a display material characterized in that a luminous layer comprising a resin and a luminous pigment is formed at least one of the both surfaces of a substrate film, and in that an image layer having a resolution of 200-1400 dpi is provided on said luminous layer or on a surface opposite said luminous layer.

The present invention is now described in detail below.

The recording sheet having luminous property is characterized in that a luminous layer comprising a resin and a luminous pigment is formed at least one of the both surfaces of a substrate film, and in that a recording layer which permits recording with a toner or an ink is provided on said luminous layer or on a surface opposite said luminous layer.

As the substrate sheet used in the present invention is one which is generally used in heat transfer printers (such as sublimation transfer printers and heat fusion transfer printers), ink jet printers and laser printers and may be, for example, a paper, a synthetic paper or a plastic sheet.

It is advantageous, from the standpoint of luminance, that the substrate sheet be a light impervious sheet when the recording layer is provided on the luminous layer. The light impervious sheet may be a plastic sheet, such as made of a thermoplastic resin, into which a white pigment such as titanium oxide, calcium carbonate or synthetic silica is added. The thermoplastic resin may be, for example, a polyester resin, an acrylic resin, a polycarbonate resin, a polyethersulfone resin or a polyolefin resin. Above all, the use of a biaxially oriented polyethylene terephthalate sheet is preferred for reasons of dimensional stability, flatness and heat resistance. A laminate of a plastic sheet with a paper may also be used.

It is necessary that the substrate sheet should be transparent when the recording layer and the luminous layer are provided on opposite to each other. As such a transparent plastic sheet, there may be mentioned a sheet obtained from a known plastic material such as a polyester resin, an acrylic resin, a polycarbonate resin, a polyethersulfone resin or a polyolefin resin.

The thickness of the substrate sheet is generally 25-250 µm and preferably 38-100 µm from the standpoint of workability and adaptability to printers.

The luminous layer for the recording sheet of this invention comprises a resin and a luminous pigment. The luminous pigment used in the luminous layer may be a pigment obtained by dissolving a sulfide of a metal such as barium, strontium, cadmium, calcium or zinc and a fluorescent dye together with a precondensate of a condensable synthetic resin and by proceeding with the condensation of the resin for immobilizing the dye in the resin; a compound which has, as a matrix, an oxide compound of the following formula (1): MAl₂O₄ (wherein M is at least one element selected from calcium, strontium and barium); a magnesium-added oxide compound having, as a matrix, a compound in which the above oxide compound is blended with magnesium; or an activated fluorescent compound obtained by adding, as an activator, europium, dysprosium or neodymium to the above oxide compound or the magnesium-added oxide compound. For example, there may be mentioned N Yako G-300M manufactured by Nemoto & Co., Ltd.

The luminous pigment may also be a compound represented by the following formula (2): (SrEu)Al₂O₄·[(SrEu)O·_n(Al_1-a-bB_bQ_a)₂O₃(OH)] wherein Q is at least one element selected from Bi, Ca, Mg and Mn, a is 0.0005≦a≦0.002, b is 0.001≦b≦0.35 and n is 1≦n≦7.

The use of N Yako G-300M is more preferred than the use of the compound of the formula (1) or (2) for reasons of obtaining clear images on a display material.

For obtaining clearer images as a display material, it is preferable to use a luminous agent which is white under the ordinary visible light. As an example of such a luminous agent, there may be mentioned a product obtained by adding Eu₂O₃ to a luminous fluorescent material comprising SrAl₂O₄:Eu, Dy (JP-A-H9-13028) or a product obtained by depositing calcium carbonate or silica on surfaces of a luminous pigment. Such a luminous agent may be commercially available as WA-300 (manufactured by Nemoto & Co., Ltd.).

Various kinds of conventional resins, such as thermoplastic resin, thermosetting resins and rubber, may be used as the resin of the luminous layer. The use of a thermosetting resin is preferred in the present invention. As the thermosetting resin, there may be used various known resins having heat-curable or light-curable property. Illustrative of heat-curable resins are urethane resins, epoxy resins, polyester (alkyd) resins, silicone resins and thermosetting acrylic resins. Illustrative of light-curable resins are acrylic resins and other known resins. By using a curable resin as a resin binder, it is possible to obtain a luminous film having excellent heat resistance and durability.

The thermosetting resin is preferably in the form of a two-components liquid composition consisting of a main agent comprising a thermosetting resin and a curing agent therefor.

In the present invention, it is preferable to use, as the resin binder, a thermosetting resin of an aliphatic (non-aromatic) type that does not contain an aromatic component. Especially, the use of an aliphatic urethane resin or a thermosetting acrylic resin is preferred for reasons of excellent weatherability, heat resistance and adhesion to the substrate film. The aliphatic urethane resin is preferably a two-components type liquid composition using an aliphatic acrylpolyol as a main agent and a non-yellowing aliphatic isocyanate (curing agent) as an auxiliary agent.

The aliphatic acrylpolyol is a polymer of an acrylic polymer or copolymer into which hydroxyl groups have been incorporated. The introduction of hydroxyl groups may be performed by copolymerizing an acrylic ester monomer having a hydroxyl group, such as β-hydroxyethyl-methacrylate, with a non-aromatic acrylic monomer such as acrylic acid or methyl methacrylate.

The non-yellowing aliphatic isocyanate is a product obtained by reacting a non-aromatic diisocyanate, such as hexamethylenediisocyanate, isophoronediisocyanate, hydrogenated methaxylenediisocyanate or norbornenediisocyanate, with a polyol, such as trimethylolpropane, glycerin or a glycol, to form an adduct, followed by removal of excess isocyanate.

When a composition comprising the above-described aliphatic acrylpolyol and non-yellowing aliphatic isocyanate is used as the resin binder, it is easy to control the glass transition point and elongation of a cured resin film obtained therefrom and, further, it is possible to obtain a luminous layer film having excellent durability, heat resistance and mechanical strengths.

The weight ratio of the luminous pigment to the above-described resin is in the range of 5:95 to 95:5. When the resin solid matter content is below 5 % by weight, a luminous layer having satisfactory strengths is not obtainable. When the amount of the luminous pigment is below 5 % by weight, it is impossible to obtain sufficient visibility in the dark. For reasons of strengths, luminous properties and, especially, visibility in the dark of the luminous layer, the weight ratio of the luminous pigment to the above-described resin is preferably in the range of 15:85 to 85:15.

It is preferred that the luminous layer have a glass transition temperature (hereinafter referred to as Tg) of 10-60°C in view of the fact that the sheet is wound into a roll during preparation. A Tg of below 10°C unavoidably causes blocking during winding or storage. A Tg of greater than 60°C causes formation of cracks in the coating during winding.

The thickness of the luminous layer is in the range of 20-200 µm, preferably 30-150 µm. When the thickness of the luminous layer is below 20 µm, sufficient visibility in the dark is not obtainable. A thickness in excess of 200 µm is undesirable from the standpoint of costs and workability. The thickness of the luminous layer is preferably 30-70 µm for reasons of visibility in the dark and workability.

In the formation of the luminous layer, it is not necessary to use a solvent when the resin binder is a liquid resin. In such a case, the liquid resin is blended with the luminous pigment to form a coating liquid having a solid matter content of 45-85 % by weight. The luminous layer may be formed by applying a coating of the coating liquid and by drying the coating, according to the conventional method. It is possible to add various conventional additives such as a surfactant, an antifoaming agent and a stabilizing agent, to the coating liquid.

If desired, a primer layer may be interposed between the substrate and the luminous layer or between the luminous layer and the recording layer, for the purpose of improving the bonding therebetween. As the primer layer, a saturated polyester resin or an urethane resin is generally used. The use of an urethane resin is particularly preferred for reasons of good bonding between the substrate and the luminous layer or between the luminous layer and the recording layer. The primer layer is applied in an amount of generally 0.5-20 g/m², preferably 0.5-10 g/m². An amount of coating below 0.5 g/m² is insufficient to provide uniform bonding. An amount of application in excess of 20 g/m² is undesirable for reasons of costs and workability.

For the purpose of improving adhesion between the substrate and the luminous layer or between the substrate and the recording layer, a surface treatment such as a chemical etching treatment (e.g. chromic acid treatment), an ionization radiation treatment (e.g. corona treatment or plasma treatment), or a chemical or physical treatment (e.g. ozone exposure, flame exposure or high voltage electric shock exposure) may be done.

In the present invention, a recording layer is provided on a surface of the luminous layer or on a surface opposite the luminous layer. The recording layer has a property of retaining a toner or an ink, especially an ink of ink jet printing, an ink of an aqueous ink ballpoint pen or an aqueous ink pen, or an ink of a sublimation dye or pigment. The recording layer may be an ink receiving layer of conventional ink jet printing sheets or a toner receiving layer of PPC recording media and has transparency especially such transparency that the luminous layer can see with naked eyes.

The ink receiving layer preferably includes at least one layer containing a binder of a water-absorbing polymeric compound or a water-soluble polymeric compound which has been subjected to a water-proofing treatment and, optionally, a pigment, a dye fixing agent or an organic or inorganic fine particles.

The water-absorbing or water-soluble polymeric compound may be, for example, polyvinyl alcohol or its derivative, polyvinyl acetal, polyvinyl pyrrolidone, starch, latex, an acrylic resin, a melamine resin, cellulose, tannin or alginic acid. The water-soluble polymeric compound which has been subjected to a water-proofing treatment is obtainable by subjecting the water-soluble polymeric compound to an insolubilizing treatment by reaction for the formation of salt, coordinate bonding, covalent bonding or hydrogen bonding.

Water-proofing property may be imparted to a coating of the water-soluble polymeric compound using a crosslinking agent which may be, for example, a cellulose reaction crosslinking agent such as a urea resin or a water-soluble melamine, an insocyanate resin or an aziridine compound.

The pigment or dye fixing agent may be, for example, pseudoboehmite, colloidal silica, an anionic surfactant or porous silica. For reasons of excellent water-resistance, dye or pigment fixing property and transparency, the use of pseudoboehmite or colloidal silica is preferred.

As a material for use in the toner-receiving layer may be, for example, an acrylic resin or a polyolefin resin such as a polyethylene resin or a polypropylene resin. For reasons of bonding with a toner, the use of a polyethylene resin is preferred. By using a toner-receiving layer having a melting point equal to or lower than that of the toner, it is possible to improve toner-receiving property, image coloring property and clearness of images. It is especially preferred that the ink-receiving layer have toner bonding property, for reasons of usability for both purposes.

The recording layer can contain organic or inorganic fine particles in an amount which does not adversely affect the luminous property thereof. By the addition of such fine particles, the transferring property during output and the fixing property of the pigment or toner may be improved. The inorganic or organic fine particles may be inorganic fine powder of naturally occurring silica, kaolin, talc, clay, calcium carbonate, titania, alumina, zirconia, zeolite, barium sulfate, magnesium hydroxide, calcium phosphate or glass or an organic powder of an acrylic resin, an urethane resin, a vinyl chloride resin, a benzoguanamine resin or a benzoguanamine/melamine/formaldehyde condensation product. Among the above inorganic fine particles, the use of silica or calcium carbonate is preferred for reasons of ink absorbing property and anti-blocking property. Among the above organic fine particles, the use of an acrylic resin or benzoguanamine resin is preferred, since excellent anti-blocking property and transferability on a printing machine are obtainable without adversely affecting the transparency. The particles are desired to be spherical in shape for reasons of workability in preparation of a coating liquid and ink permeability.

The recording layer may contain surface roughening agent in the form of particles. The particles of the surface roughening agent have a weight average particle diameter of in the range of 0.5-30 µm. A particle size of the surface roughening agent below the above range fails to form roughness in the surface of the recording layer and is ineffective as the surface roughening agent. Further, the fixing property of the pigment ink cannot be improved. When the particle size is greater than the above range, the roughness of the recording layer is so great that transfer of toner images is not uniform, that fixation of the transferred toner image with a roll is insufficient, and that clear images are not obtainable because of deformation of dots at the time of formation of letter or image patterns by ink jet printing. From the standpoint of formation of surface roughness, pigment fixation, prevention of non-uniformity of image transfer and clearness of image, the particle diameter of the surface roughening agent is preferably 2-25 µm.

When the surface roughening agent is incorporated into the recording layer, the amount of the agent is suitably selected from the range in which the transparency and the luminous property of the luminous layer are not adversely affected and is generally in the range of 0.1-20 % by weight based on the recording layer. An amount of the surface roughening agent below 0.1 % by weight will cause the blocking. Too large an amount of the surface roughening agent above 20 % by weight is undesirable because the image reproducibility, transparency and luminous property are reduced.

The recording layer may be prepared by a method which includes, for example, dissolving or dispersing the above-described polymeric compound and, if desired, surface roughening agent in a solvent each in a given amount to obtain a coating liquid having a solid matter content of 10-15 % by weight, applying the coating liquid over a substrate sheet, over an optionally formed primer layer or over a luminous layer in the conventional manner, and drying the coating. In this case, various conventionally used additives such as a surfactant, a lubricant or a stabilizer may be incorporated into the coating liquid.

The thickness of the recording layer is in the range of 5-30 µm, preferably 7-20 µm. When the thickness of the recording layer is below 5 µm, ink absorbing property and toner receiving property of the layer are not satisfactory. When the thickness exceeds 30 µm, the sheet is apt to curl. The formation of curls is not easy and is also undesirable from the standpoint of costs.

The recording sheet according to the present invention, when composed of a substrate sheet, a luminous layer and a recording layer which are laminated in this order, may be provided with an adhesive layer on a surface opposite the luminous layer.

The recording sheet according to the present invention, when composed of a substrate sheet, a luminous layer and a recording layer which are laminated such that the luminous layer and the recording layer are located opposite sides of the substrate sheet, a white coating layer may be provided over the luminous layer so that higher luminance may be obtained. When a white luminous agent used, whiteness of the surface on which letter or image patterns to be observed are formed is improved. The white coating layer includes a binder and a white pigment as main ingredients. The binder may be suitably selected from thermosetting and thermoplastic resins. For example, from the standpoint of bonding with the luminous layer, it is preferred that the same binder as used in the luminous layer be used. As the white pigment, inorganic pigment such as titanium oxide, zinc white, talc, clay, calcium carbonate, silica, aluminum hydroxide or aluminum oxide, or an organic pigment such as white acrylic resin particles may be used. Above all, the use of titanium oxide is preferred for reasons of concealing property. The particle diameter of the white pigment is 0.1-50 µm in terms of weight average particle diameter. When the particle size is outside of the above range, bonding to the luminous layer and whiteness are reduced. From the standpoint of bonding to the luminous layer and luminance depending upon the whiteness, the white pigment preferably has a particle diameter of 0.2-30 µm. The amount of the white pigment relative to the binder is suitably selected from the intended whiteness and may be such that the total luminous transmittance of the white layer is 30 % or less.

The white coating layer may further includes organic fine particles such as powder of a synthetic resin such as an acrylic resin, a benzoguanamine resin or a benzoguanamine/malamine/formaldehyde resin for the purpose of improving transference on printers and prevention of blocking.

When patterns are formed on the recording layer of the recording sheet of the present invention using an output device such as a printer, it is necessary that the output be done to provide a printer resolution of 200-1400 dpi (dots per inch). When the printer resolution is below 200 dpi, the image clearness and impact are reduced due to low resolution of the outputted letter or image patters. When the resolution exceeds 1400 dpi, the outputted letter or image patterns will adversely affect the luminous property so that the luminous efficiency and light emitting efficiency of the luminous pigment are reduced, although clear images are obtainable in the daytime. This is not advantageous because so called visibility in the dark, namely the property that the letter or image patterns are able to be observed in the dark without using a light source, is reduced. This is ascribed to the prevention of a phenomenon that light from the luminous layer passes through the space between dots and through translucent portions and appears on the pattern. The printer resolution is desirably suitably selected according to the size of the sheet to be outputted. For example, when the sheet size exceeds A3, a clear image may be obtained while ensuring visibility in the dark, even with relatively low printer resolution.

The display material according to the present invention comprises the above-described recording sheet whose recording layer has an image having a resolution of 200-1400 dpi, preferably 300-1200 dpi. The image may be formed by using various types of above-mentioned printers or in any other printing methods.

The display material of the present invention may be displayed, as advertising media, etc., at locations selected according to the kind of the image.

Examples:

The present invention will be next described in detail with reference to examples which do not limit the present invention.

The properties of recording sheets and display materials are evaluated according to the following methods.

[Method of Evaluation] 1. Visibility

Using Prospert Photomach Color Printer PM-2000C (manufactured by EPSON Inc.), letters are printed with resolution of 180, 360, 720 and 1440 dpi. The image is evaluated in the daytime and at night with naked eyes at a position 1 m away therefrom according to the following ratings:

○ : the pattern is able to see without problems both in the daytime and at night

▵ : the pattern is able to see in the day time but not at night

X : the pattern is unable to see in the daytime and at night

2. Bonding

The bonding between the luminous layer and the recording layer is evaluated according to the matrix test method (JIS K-5400).

5:: deficient portions are zero
4:: deficient portions are within 5 %
3:: deficient portions are 5-15 %
2:: deficient portions are 15-35 %
1:: deficient portions are more than 35 %

3. Drying Efficiency of Ink

Using Mach Color Printer PM-700C (manufactured by EPSON Inc.), letters are printed and the image is evaluated according to the following ratings:

○ : drying time (dryness is detected by touch with a finger) is shorter than 60 seconds

▵ : not shorter than 60 seconds but shorter than 3 minutes

X : longer than 3 minutes

4. Roll Winding

During winding around a roll, surface appearance of the coat is observed with naked eyes

○ : able to be wound without blocking and occurrence of cracks

X : blocking or cracking occurs

5. Heat Resistance

A toner or ink receiving layer is applied and then dried at determined conditions (140°C, 3 minutes). The dried sheet is then tested for flatness and transferability on a printer.

○ :: no waving and good transferability
▵ :: waving exists but transferability is good
X :: waving exists and transferability is no good

6. Curling

Rolled product is cut into A4 size sheet. The cut sheet is placed on a flat table with the luminous layer being oriented upward. An average of heights of the four corners of the sheet from the surface of the table is measured. The evaluation as based on the following ratings:

○ :: not greater than 10 mm
▵ :: 10-20 mm
X :: greater than 20 mm

Example 1

A coating liquid for forming a luminous layer was prepared by mixing 43.5 parts by weight of acrylpolyol (hydroxyl group value: 17.5), 47.8 parts by weight of luminous pigment (G-300M manufactured by Nemoto & Co., Ltd.), 4.4 parts by weight of an additive, and 4.3 parts by weight of a curing agent (NCO %: 12.6).

On one side of a white polyethylene terephthalate sheet having a thickness of 50 µm, an adhesion layer made of an urethane resin and having a thickness of 1 µm was formed. Then, the above coating liquid was applied onto the primer layer and dried to obtain a luminous layer having a thickness of 50 µm and Tg of 35°C.

A coating liquid for forming a recording layer was then prepared by mixing 6.4 parts by weight of acetoacetylated polyvinyl alcohol (saponification degree: 99 mole %, polymerization degree: 1,000), 2 parts by weight of polyvinyl pyrrolidone (weight average molecular weight: 630,000), 8 parts by weight of an acidic liquid containing colloidal silica (Snowtex ST-AK manufactured by Nissan Chemical Industry Ltd.), 10 parts by weight of ethanol and 73.6 parts by weight of water.

After an adhesion layer made of an urethane resin and having a thickness of 1 µm had been formed on the luminous layer, the coating liquid for forming a recording layer was applied onto the adhesion layer and dried to obtain a recording layer (ink receiving layer) having a thickness of 10 µm. Thus, a recording sheet having luminous property according to the present invention was fabricated.

Example 2

A recording sheet was fabricated in the same manner as that in Example 1 except that the coating liquid for the formation of a recording layer was changed as follows.

Thus, a coating liquid for forming a recording layer was prepared by mixing 7 parts by weight of polyvinyl alcohol (polymerization degree: 1700, saponification degree: 88 mole %), 1 part by weight of polyvinyl pyrrolidone (weight average molecular weight: 630,000), 2 parts by weight of polystyrene sulfonic acid salt (Chemistat 6120 manufactured by Sanyo Kasei Inc.), 0.2 part by weight of dimethylol glyoxal monoureine (cellulose reaction crosslinking agent), 69.66 parts by weight of water and 0.04 part by weight of synthetic silica (average particle diameter: 6 µm). The coating liquid was applied on an adhesive layer and dried to obtain a recording layer (ink receiving layer) having a thickness of 25 µm.

Example 3

The above coating liquid was applied onto one of the primer layers formed on both sides of a transparent polyethylene terephthalate sheet having a thickness of 50 µm, and dried to obtain a luminous layer having a thickness of 50 µm and Tg of 35°C.

The coating liquid for forming a recording layer was applied onto that adhesion layer located opposite the adhesion layer on which the luminous layer was formed using a wire bar, and dried to obtain a recording layer (ink receiving layer) having a thickness of 10 µm. Thus, a recording sheet having luminous property according to the present invention was fabricated. The luminous layer was irradiated with light of 1000 LX (lux) for 10 minutes and then measured for its luminance using a luminance meter (BM-8 manufactured by Topcon Inc.; surface of the sample table: black). The luminance was 400 mcd/m² (value at 1 minute).

Comparative Example 1

Example 1 was repeated in the same manner as described except that a sheet (Luminova (tradename) manufactured by Nemoto & Co., Ltd.; obtained by keading a luminous pigment with a polyvinyl chloride resin) was used in lieu of the luminous layer of Example 1. Thus, a recording sheet was fabricated by applying a coating liquid for the formation of a recording layer having the same composition as that of Example 1.

Example 4

A recording sheet was fabricated in the same manner as that in Example 3 except that a luminous pigment (WA-300 manufactured by Nemoto & Co., Ltd.) was used in lieu of the luminous pigment (G-300M manufactured by Nemoto & Co., Ltd.) of the coating liquid for the formation of a luminous layer. The thus obtained recording sheet had a luminance of 200 mcd/m² (value at 1 minute). An image pattern was formed on the recording layer using Mach Color Printer PM-700C (manufactured by EPSON Inc.). The image, when observed under ordinary visible light, was found to be clearer than those of Examples 1-3. The physical properties of the sheet were evaluated according to the above-described methods.

Example 5

Example 4 was repeated in the same manner as described except that a coating liquid for forming a white layer having the composition shown below was applied onto the luminous layer of Example 4, and dried to obtain a recording sheet. The white layer had a total luminous transmittance of 25 %. The recording sheet had a luminance of 200 mcd/m² (value at 1 minute). An image pattern was formed on the recording layer using Mach Color Printer PM-700C (manufactured by EPSON Inc.). The image, when observed under ordinary visible light, was found to be clearer than that of Example 4. The physical properties of the sheet were evaluated according to the above-described methods.

Coating Liquid for Forming White Layer:

The coating liquid for the formation of the white layer was prepared by mixing 60 parts by weight of acrylpolyol (hydroxyl group value: 17.5), 12 parts by weight of white pigment (Tipaque manufactured by Ishihara Sangyo Co., Ltd.), 1.2 parts by weight of an additive, 3.8 parts by weight of a curing agent (NCO %: 12.6), 14 parts by weight of toluene and 9 parts by weight of methyl cellosolve acetate.

Example 6

A recording sheet was fabricated in the same manner as that of Example 3 except that the ink receiving layer was substituted by an ink fixing layer obtained by applying a coating liquid composed of 30 parts by weight of a polyester resin, 20 parts by weight of toluene, 20 parts by weight of methyl ethyl ketone and 30 parts by weight of an additive, followed by drying of the coating. Letter and image pattern were printed with a resolution of 600 dpi on a surface of the recording sheet opposite the luminous layer using a heat transfer printer (MD-2300 manufactured by ALPS Inc.). The pattern was able to see in the daytime and at night without difficulties. Thus, there was obtained a display material having the image which was able to see clearly especially in the daytime.

The results of evaluation of each of the articles obtained in Examples 1-5 and in Comparative Example 1 are summarized in Tables 1-1 and 1-2.

	Visibility	Bonding
	180 dpi	360 dpi	720 dpi	1440 dpi
Example 1	X	○	○	▵	5
Example 2	X	○	○	▵	5
Example 3	X	○	○	▵
Example 4	X	○	○	▵
Example 5	X	○	○	▵
Comp. Ex. 1					1

	Drying Efficiency	Roll Winding	Heat Resistance	Curling
Example 1	○	○	○	○
Example 2	○	○	○	○
Example 3	○	○	○	○
Example 4	○	○	○	○
Example 5	○	○	○	○
Comp. Ex. 1			X

With the recording sheet having luminous property according to the present invention, it is possible to easily output letter and image patterns, prepared by, for example, a personal computer, using an ink jet printer, an in jet plotter, a heat transfer printer (sublimation transfer printer, fusion transfer printer), a laser printer, etc. Since the recording sheet having luminous property according to the present invention is a laminate of a luminous layer and a recording layer, it is not necessary to apply a luminous sheet to a recording sheet. Thus, working efficiency is improved.

When a letter and image pattern is printed on the recording sheet having luminous property according to the present invention with a printer resolution of 200-1400 dpi to form a display material, the letter and image pattern is clearly indicated by emitted light in a bright or dark place without need of illumination devices. Thus, a fossil fuel such as electric power is not necessary and, hence, display materials such as advertising materials and signboards which are non-harmful for the global atmosphere is obtainable.

When a white coating layer is provided on a luminous layer, the luminance of the luminous layer is improved. In this case, when a white luminous agent is used, the surface is seen to be whiter under the ordinary visible light. Thus, the pattern on the recording layer can be clearly shown.

Claims

A recording sheet, characterized in that a luminous layer comprising a resin and a luminous pigment is formed on at least one of both surfaces of a substrate film, and in that a recording layer which permits recording with a toner or an ink is provided on said luminous layer or on a surface opposite said luminous layer.
A recording sheet, characterized in that a luminous layer comprising a resin and a luminous pigment is formed on one of both surfaces of a substrate film, in that a recording layer which permits recording with a toner or an ink is provided on a surface opposite said luminous layer, and in that a white layer is laminated on said luminous layer.
A recording film as recited in claim 1 or 2, wherein the amount of the luminous pigment is 5-95 % by weight based on a total weight of the luminous layer.
A recording film as recited in any one of claims 1 through 3, wherein the thickness of the luminous layer is 20-200 µm.
A recording film as recited in any one of claims 1 through 4, wherein the luminous layer has a glass transition temperature (Tg) of 10-60°C.
A recording film as recited in any one of claims 2 through 5, wherein the white layer has a luminous transmittance of 30 % or less.
A display material characterized in that a luminous layer comprising a resin and a luminous pigment is formed on at least one of both surfaces of a substrate film, and in that an image layer having a resolution of 200-1400 dpi is provided on said luminous layer or on a surface opposite said luminous layer.
A display material as recited in claim 7, characterized in that a white layer is laminated on said luminous layer.
A display material as recited in claim 7 or 8, wherein the luminous layer has a glass transition temperature (Tg) of 10-60°C.
A display material as recited in any one of claims 7 through 9, wherein the white layer has a light transmittance of 30 % or less.