JPH07218708A - Luminous retroreflective sheet - Google Patents

Abstract

(57) [Abstract] [Purpose] Useful for signs such as road signs and construction signs, license plates for vehicles such as automobiles and motorcycles, safety materials such as clothes and life preservers, or marking of signs and vehicles. Of various retroreflective sheets. [Structure] A light-transmissive top film, a base film, and a connecting wall for partially connecting both films while leaving a gap between the films, and a retroreflective element is provided on the top film and / or the base film. A retroreflective sheet, which is uniformly and densely arranged over the entire surface, wherein the connecting wall and / or the base film contains a luminous substance. [Effect] It has excellent visibility due to reflection of sunlight in the daytime and excellent visibility due to retroreflection of headlights of automobiles at night, and also has excellent nighttime visibility due to luminosity even in darkness at night.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to signs such as road signs, construction signs, license plates for vehicles such as automobiles and motorcycles, safety materials such as clothes and life preservers, or signs.
The present invention relates to a retroreflective sheet useful for marking vehicles and the like.

[0002]

2. Description of the Related Art Conventionally, a retroreflective sheet that retroreflects light toward a light source is well known, and is widely used in the above-mentioned fields of application by utilizing its retroreflectivity.

In particular, it is composed of a light-transmissive top film, a base film, and a connecting wall for partially connecting the two films while leaving a gap between the two films. The top film and / or the base film have retroreflective properties. The retroreflective sheet in which the elements are uniformly and densely arranged over the entire surface can be obtained year by year because excellent retroreflective performance can be obtained by using a low refractive index gas such as air existing between the top film and the base film. Usage is expanding.

However, these retroreflective sheets are
Naturally, the light is retroreflected only when it receives light from the light source and exhibits excellent visibility in the light source direction.For example, at night, when there is no light source, the visibility is improved. Even if there is a light source, the visibility is significantly inferior even if there is a light source, and the visibility is significantly different from the light source direction. Was something I couldn't get.

For this reason, in recent years, when higher safety and advertising effects have been demanded, the conventional retroreflective sheet having only retroreflective performance has insufficient visibility, particularly at night. In these cases, an excellent retroreflective sheet that has both visibility when there is no light source or limited light source and visibility in a direction different from the light source direction has been strongly desired.

In order to meet these demands, several methods for improving the visibility of the retroreflective sheet have been studied in the past. For example, Japanese Patent Laid-Open No. 173008/1993 discloses a retroreflective sheet having a light reflecting layer on the lower hemisphere. There has been proposed a method of improving visibility at night or the like by providing a luminous phosphor layer on the back surface of the transparent transparent sphere and the transparent fixing layer.

However, in this method, since the light-storing luminescent material layer is located below the substantially opaque retroreflective transparent sphere, in order to incorporate light for storing light into the light-storing luminescent material layer, Further, in order to emit the accumulated light and emit it from the surface layer, it is necessary to partially form a portion without a retroreflective transparent sphere, and in that case, the retroreflective transparent sphere is inevitably spread over the entire surface of the fixing layer. Since they cannot be arranged densely, it is difficult to obtain excellent retroreflective performance, and there are drawbacks such that a complicated process for forming a portion without a retroreflective transparent sphere is required. .

Further, even if a relatively expensive phosphorescent luminescent material is added to and contained in the lower layer of the retroreflective transparent sphere,
It also has the drawback that it cannot perform its function very well and is very inefficient.

In addition, as a method of improving the visibility of the retroreflective sheet, a method of using lighting equipment such as a fluorescent lamp in combination with the retroreflective sheet has been proposed. However, there are drawbacks such as high cost for providing the lighting equipment and complicated work for maintenance and inspection of the lighting equipment.

[0010]

In view of these drawbacks of the prior art, the present invention uses a very simple and inexpensive method.
It is intended to provide a retroreflective sheet having excellent visibility even at night.

The inventors of the present invention have studied various visibility of the retroreflective sheet, and as a result, the retroreflective sheet having excellent visibility can be obtained by a suitable combination arrangement of the retroreflective element of the retroreflective sheet and the layer containing the luminous substance. It has been found that a reflection sheet can be obtained.

[0012]

According to the present invention, there is thus provided a light-transmissive top film, a base film, and a connecting wall for partially connecting both films while leaving a gap between the films. In a retroreflective sheet in which retroreflective elements are uniformly and densely arranged on the entire surface of the film and / or the base film,
Provided is a night-light retroreflective sheet characterized in that the connecting wall and / or the base film contains a night-light emitting material.

The present invention will be described in detail below with reference to FIGS.

The retroreflective sheet for night light of the present invention comprises a light-transmissive top film, a base film, and a connecting wall for partially connecting the two films while leaving a gap between the two films. Retroreflective elements are uniformly and densely arranged on the entire surface of the base film.

The retroreflective element used in the retroreflective sheet for luminescence of the present invention includes a retroreflective element generally called a cube-corner type in which opposing surfaces face each other at an angle of about 90 °, and glass beads. A retroreflective element generally called a lens type, which is composed of a high refractive index transparent microsphere and a light reflecting film such as a metal vapor deposition film formed on substantially the lower hemisphere of the microsphere, is used.

FIGS. 1 to 3 are examples of cross-sectional schematic diagrams of a night light retroreflective sheet of the present invention using a cube-corner type retroreflective element.

1 to 3, reference numeral 1 denotes a light-transmissive top film, and cube-corner type retroreflective elements 2 are uniformly and densely arranged on the entire back surface of the top film. Reference numeral 3 denotes a base film, which in FIG. 1 is partially connected to the top film by a connecting wall 4 formed by a method such as partially heating and melting the base film. In FIGS. 2 and 3, the base film is partially connected to the top film by a connecting wall 4 separately formed of an adhesive resin, instead of the connecting wall formed by partially heating and melting the base film. In FIG. 1, the base film is formed into a connecting wall, but a top film may be formed into a connecting wall. A gap 5 is partially present between the top film and the base film, and a low refractive index gas such as air is present in the gap.

In the night-light retroreflective sheet of the present invention using the cube-corner retroreflective element, since the cube-corner retroreflective element is substantially transparent and light-transmissive, the luminous substance is a cube-corner type. The function of the retroreflective element can be sufficiently exerted even if it is added to any part of the back surface of the retroreflective element, and in FIG. In Fig. 3, the base sheet, and in Fig. 3, the connecting wall contains the phosphorescent material 6. In FIG. 2, it is preferable that the connecting wall is light-transmissive in order to effectively function the phosphorescent material in the base film located under the connecting wall.

In the night-light retroreflective sheet of the present invention using the cube-corner type retroreflective elements as shown in FIGS. 1 to 3, the light emitted from the light source is cube-corner type as shown in the optical path A. The light enters the retroreflective element, is totally reflected at the interface with the low refractive index gas, and is retroreflected toward the light source, and exhibits excellent retroreflective performance.

Similarly, in the night light retroreflective sheet of the present invention shown in FIGS. 1 to 3, the light is retroreflected from the light source under the condition that the condition of total reflection at the interface between the cube-corner type retroreflective element and the low refractive index gas is not achieved. The light entering the reflection sheet passes through the cube-corner retroreflective element as shown by optical paths B, C, and D and reaches the connecting wall and the base film. At this time, light is accumulated by the luminous substance contained in the connecting wall and / or the base film, and is gradually emitted as light from the luminous substance even after the light from the light source disappears.

Therefore, the night-light retroreflective sheet using the cube-corner type retroreflective element of the present invention as shown in FIGS. 1 to 3 reflects light such as sunlight in the daytime and has excellent visibility. Of course, even at night, retroreflect light from a light source such as a car headlight,
It provides excellent visibility for automobile drivers, etc., and also stores sunlight during the day, fluorescent lights at night, lighting from automobile headlights, etc., even in the darkness where the light source is completely gone. It gradually emits light and emits light to provide excellent luminosity and night visibility to drivers and pedestrians.

FIG. 4 and FIG. 5 are examples of cross-sectional schematic diagrams of the night light retroreflective sheet of the present invention using a lens type retroreflective element.

In FIGS. 4 and 5, 1 is a light-transmitting top film and 3 is a base film. Similar to FIG. 1, in FIG. 4, the connecting wall 4 formed by molding the base film.
The top film and the base film are partially connected by. In FIG. 5, as in FIGS. 2 and 3, the top film and the base film are partially connected by a connection wall 4 formed as an adhesive connection wall separately from the base film.

A lens type retroreflective element 9 formed by a high refractive index transparent microsphere 7 such as glass beads and a light reflecting film 8 such as a metal deposition film is embedded in the base film in the light reflecting film portion. Held in. There is a partial gap 5 between the top film and the base film,
A low refractive index gas such as air exists in the gap.

In the night-light retroreflective sheet of the present invention using the lens-type retroreflective element, since the lens-type retroreflective element is substantially opaque and difficult to transmit light, the back surface of the lens-type retroreflective element is used. It is difficult to receive the light for storing light, and even if the light is received, it is difficult to transmit the light through the lens-type retroreflective element. I can't show it to the full.

That is, for example, in FIG.
1 is added to both layers of the base sheet and the connecting wall formed from the base sheet as in FIG. 1, but among the luminous substances in the base sheet and the connecting wall, the function is sufficiently exerted. , Those located only on the gap or the surface of the lens-type retroreflective element, and those located below the back surface of the lens-type retroreflective element do not exhibit their functions sufficiently.

Therefore, if the lens-type retroreflective elements are densely arranged on the base sheet in order to improve the retroreflective performance (generally, they are arranged so as to cover 70 to 90% of the surface area of the base sheet). ), The gap portion of the lens-type retroreflective element is reduced, and the luminous performance is deteriorated.

If the area of the connecting portion is increased in order to enhance the luminous performance and the lens type retroreflective elements are arranged relatively sparsely, the retroreflective performance will be deteriorated. It ends up.

Therefore, in the luminescent retroreflective sheet of the present invention using the lens type retroreflective element, in order to use the luminescent material efficiently, as shown in FIG. 5, the luminescent material is provided only in the connecting wall. Is preferably added.

In order to exert a good balance between the luminous performance and the retroreflective performance, it is preferable to arrange the connecting wall portion that exerts the luminous performance and the gap holding portion that mainly exerts the retroreflective performance in a well-balanced manner. Partial area ratio, that is, the area of the bonded portion where the top film is bonded to the connecting wall to the total area of the light-transmitting top film is 10 to 50.
%, Preferably 20 to 50%, more preferably 30 to 40%.

In the night-light retroreflective sheet of the present invention using the lens-type retroreflective element as shown in FIGS. 4 and 5, the light emitted from the light source has the lens-type retroreflective property as shown in the optical path A. The light enters the element, is refracted by the lens, is reflected by the light reflecting film, and is retroreflected toward the light source.

Further, the light entering the connecting portion in FIGS. 4 and 5 passes through the light-transmissive top film as shown by optical paths B and C, reaches the connecting wall, and is contained in the connecting wall. Light is accumulated by the luminous substance, and is gradually emitted as light from the luminous substance even after the light from the light source is gone.

Thus, the night light retroreflective sheet using the lens type retroreflective element of the present invention as shown in FIGS. 4 and 5 is the night light retroreflective sheet using the cube corner type retroreflective element described above. Similarly, with excellent retroreflective performance,
It exhibits excellent luminosity and night visibility.

However, in the night light retroreflective sheet using the lens-type retroreflective element that is difficult to transmit light, as described above, the nightlight performance is inevitably exerted mainly by the connecting wall portion, and the retroreflective performance by the gap holding portion. Since it is exhibited, the retroreflective element is light-transmissive, and the night-light retroreflective sheet using the cube-corner type retroreflective element capable of exerting both the functions of excellent nightlight performance and retroreflective performance in the gap retaining portion. Its luminous performance and /
Alternatively, the retroreflective performance tends to be low.

Therefore, in the present invention, in order to achieve the best night light performance and retroreflective performance, it is possible to exhibit more excellent retroreflective performance, and it is a cube-corner type retroreflective property having light transmittance. It is preferable to use an element, and in particular, the base film has a luminescent material in all layers, and the connecting wall portion also has luminescent performance, and luminescent performance over the entire retroreflective sheet. For example, as shown in FIGS. 1 and 2. It is most preferable to have such a structure.

In producing the retroreflective sheet of the present invention, for example, the Japanese Patent Publication No. 61-13561 and Japanese Patent Publication No. 63-143502 are provided except that the luminous substance is arranged in the preferable portion as described above. It can be produced by a conventionally known method as described in JP-B-60-194405, JP-B-5-11101 and the like.

In the present invention, since it is not necessary to take a non-uniform arrangement structure of retroreflective elements as described in JP-A-5-173008, a complicated process for providing the non-uniform arrangement structure. Is completely unnecessary.

The luminescent material used for the retroreflective sheet of the present invention is not particularly limited, and conventionally known sulfide-based luminescent materials, metal oxide-based luminescent materials,
A radioactive substance type luminous substance or the like may be used, but a metal oxide type luminous substance or the like which has no environmental problems and is excellent in the luminous performance is most preferably used.

In the present invention, for the purpose of improving the luminescent performance, it is also a preferred embodiment to provide a light-reflecting layer such as a white pigment-containing layer on the back surface of the luminescent material-containing layer.

In the present invention, it is also one of the preferred embodiments to add a fluorescent colorant such as a fluorescent dye into the top film or the like to further improve the visibility by fluorescent coloring in addition to retroreflective performance and night light performance. .

In the luminescent retroreflective sheeting of the present invention, the light-transmissive top film and the base film are connected by a connecting wall which partially connects the two films while leaving a gap between them. Considering the processability of the retroreflective sheet, that is, the retroreflective sheet is cut into an arbitrary size and arbitrary shape, the intrusion of rainwater or the like into the gap from the cut end recurs. The connecting wall is formed in a continuous line so that the retroreflective performance of the retroreflective sheet does not deteriorate significantly over the entire reflective sheet.
It is preferably formed as a so-called capsule-type retroreflective sheet having a large number of sealed small compartments partitioned by an area of about m2.

[0042]

The present invention will be described in more detail with reference to the following examples.

Example 1 A transparent acrylic film containing polymethylmethacrylate as a main component was heat-embossed to have a light transmissive structure having a cube-corner retroreflective element having a base of about 200 μm and a height of about 80 μm on one surface. Sex top film was created.

On the other hand, on a polyethylene terephthalate film having a thickness of about 20 μm, a thickness of about 50 parts by weight of titanium oxide was added to 100 parts by weight of an acrylic copolymer resin containing ethyl acrylate-methyl methacrylate as a main component. 30μm white film layer and ethyl acrylate-
About 100 parts by weight of acrylic copolymer resin containing methyl methacrylate as a main component, a thickness of about 200 μm containing 100 parts by weight of a phosphorescent pigment (Hoechst Co., Ltd., “Lumilux”) as a sulfide type luminous substance. A luminescent base film was laminated and formed by a casting method.

Next, a light-transmissive top film was placed on the luminescent base film, and a metal roll having a surface temperature of about 190 ° C. and a surface temperature of about 60 ° C. on which a mesh-shaped convex engraving having a line width of about 0.3 mm was applied. The top film side was passed through the rubber rolls while being pressed so that the top film side was in contact with the rubber rolls, and heat embossing was performed to prepare a luminescent retroreflective sheet of the present invention.

As shown in Table 1, the obtained sheet was excellent in both night light performance and retroreflective performance.

Example 2 A luminescent retroreflective sheet was produced in the same manner as in Example 1 except that a metal oxide type luminescent material was used instead of the sulfide type luminescent material as the luminescent material. As shown in Table 1, the obtained sheet was excellent in both night light performance and retroreflective performance.

Example 3 A process in which a polyethylene resin film having a thickness of about 30 μm is laminated on a paper is heated to about 105 ° C., and glass beads having an average particle diameter of about 65 μm and a refractive index of about 1.91 are uniformly added to the paper. Densely disperse and press with a nip roll to embed the glass beads in the polyethylene resin film up to about 1/3 of its diameter. Process the glass beads in the paper surface using aluminum using a vacuum deposition machine to a thickness of about 0.1 μm It vapor-deposited.

Next, the glass substrate on which the glass beads were embedded was laminated with the same luminous base film and white film layer laminate as in Example 1 on the aluminum vapor deposition side so that the base film side was in contact, and the glass beads were heated and pressed. The base film was laminated so as to be embedded up to about ⅓ of its diameter, and then the polyethylene resin film laminating process paper was peeled off from this laminate.

Then, a non-stretched acrylic film having a thickness of about 75 μm was superposed on the exposed glass beads as a light-transmitting top film, and heat-embossing was carried out in the same manner as in Example 1 to perform retroluminescence sheet of the present invention. Made. About 35% of the total area of the light-transmitting top film was the area of the bonded portion where the top film was in contact with the connecting wall.

As shown in Table 1, the obtained sheet had both night-light performance and retroreflective performance.

Comparative Example 1 Commercially available capsule lens type retroreflective sheet [Nikka Polymer
"Nikkalite ULS812" manufactured by Co., Ltd.] was used to compare the night light performance and the retroreflective performance. As shown in Table 1, the retroreflective performance was excellent, but no visibility was shown in the dark room, and the night-light performance was poor.

The methods for measuring and evaluating the night light performance and retroreflective performance are as follows.

(1) Luminous performance The obtained luminous retroreflective sheet is cut into a length of 10 cm and a width of 10 cm, and the distance is about 0.5 m under two fluorescent lamps of 110 W.
Leave for 10 minutes, then in a dark room for about 10 minutes and about 30 minutes.
After a minute, the visible distance was measured and evaluated according to the following scores.

5 ... Can be clearly seen from a distance of 20 m. 4 ... ・ Somehow visible from a distance of 20m. 3 ... ・ Almost not visible from a distance of 20m, but visible at a distance of up to 10m. 2 ・ ・ Almost not visible from a distance of 10m, but visible at a distance of up to 5m. 1 ... Cannot be seen.

(2) Retroreflective performance The retroreflective performance was measured using the following measuring machine. The angle condition was that the observation angle was 0.2 ° and the incident angle was 5 °. Measuring machine:
Advanced Retro Technology "Model 920"

[0057]

The present invention comprises a light-transmissive top film,
What is claimed is: 1. A retroreflective sheet comprising a base film and a connecting wall that partially connects the two films while leaving a gap between the films, and a night light such as a luminous phosphor in the connecting wall and / or the base film. The present invention relates to a night-light retroreflective sheet containing a functional substance.

The night-light retroreflective sheet of the present invention reflects light such as sunlight in the daytime and exhibits excellent visibility, and also at night, reflects light from a light source such as an automobile headlight. Reflects and provides excellent visibility to the driver of the car, etc., and also stores sunlight during the day, fluorescent light at night, lighting of automobile headlights, etc.
Even in the darkness where the light source is completely emitted, the light is gradually emitted to emit light, and provides excellent luminosity and night visibility to a driver or a pedestrian.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of a luminescent retroreflective sheeting of the present invention, which uses a cube-corner type retroreflective element and has a connecting wall formed by molding a base film containing a luminescent material. is there.

FIG. 2 is a luminescent retroreflector of the present invention using a cube-corner type retroreflective element and having a base film containing a luminescent material and a separately formed adhesive connecting wall containing no luminescent material. It is a cross-sectional schematic diagram of a reflection sheet.

FIG. 3 is a luminescent retroreflector of the present invention using a cube-corner type retroreflective element and having a base film containing no luminescent material and a separately formed adhesive connecting wall containing a luminescent material. It is a cross-sectional schematic diagram of a reflection sheet.

FIG. 4 is a schematic cross-sectional configuration diagram of a luminescent retroreflective sheet having a connecting wall formed by molding a base film containing a luminescent material, using a lens-type retroreflective element.

FIG. 5 is a luminescent retroreflective film of the present invention using a lens-type retroreflective element and having a base film containing no luminescent material and a separately formed adhesive connecting wall containing a luminescent material. It is a cross-sectional schematic diagram of a sheet.

[Explanation of symbols]

 1 ・ ・ Light-transmitting top film 2 ・ ・ ・ ・ ・ ・ Cube-corner type retroreflective element 3 ・ ・ ・ ・ Base film 4 ・ ・ ・ ・ ・ ・ Connecting wall 5 ・ ・ ・ ・ ・・ Gap 6 ・ ・ ・ ・ ・ ・ Luminescent substance 7 ・ ・ ・ ・ ・ ・ ・ ・ High refractive index transparent microspheres 8 ・ ・ ・ ・ Light reflecting film 9 ・ ・ ・ ・ ・ ・ ・ ・ Lens type retroreflective element A, B, C, D ... ・ Optical path of light emitted from light source

[Table 1]

Claims (7)

[Claims] 1. A light-transmissive top film, a base film, and a connecting wall for partially connecting both films while leaving a gap between the films.
Alternatively, in the retroreflective sheet in which the retroreflective elements are uniformly and densely arranged on the entire surface of the base film, the connecting wall and / or the base film contains a luminous substance. Luminous retroreflective sheet. 2. The luminous retroreflective sheet according to claim 1, wherein the retroreflective element is a cube-corner type retroreflective element. 3. The luminous retroreflective sheet according to claim 1, wherein the retroreflective element is a lens-type retroreflective element. 4. The total area of the light-transmitting top film,
The luminous retroreflective sheet according to claim 3, wherein an area of an adhesive portion where the top film is adhered to the connecting wall is 10 to 50%. 5. The retroreflective sheet for luminescent light according to claim 1, wherein the luminescent material is contained only in the connecting wall. 6. The night-light retroreflective sheet according to claim 1, wherein the luminous substance is a non-radiative substance. 7. The night-light retroreflective sheet according to claim 6, wherein the non-radiation-based substance is a metal oxide-based phosphorescent pigment.