JPH11326609A - Wide observation angle diffuse reflection sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reflection sheet having a wide visible observation angle, high luminance and superior whiteness by having a binder layer, a layer of spherical or amorphous particles having a specific average particle size and a vapor deposited film layer on a base. SOLUTION: This reflection sheet has the binder layer 2, a layer 3 of the spherical or unshaped particles having a mean particle size of 5 to 150 μm and the vapor deposited film layer 4 in this order on the base 1. A biaxially stretched film of polyester, etc., which are stock mainly taking outdoor use into consideration are adequately used as the base 1. An acrylic adhesive, etc., are appropriately as the binder layer 2. Spherical or amorphorous particles are used as the shape of the fine particles forming the shape of the reflection layer on the base 1. The surface shape of the particles is preferably a shape, having ruggedness to give rise to the diffusion and reflection of incident light. Furthermore, the fine particles are in part exposed above from the surface of the binder layer 2, and about 80% of the grain size of the fine particles are preferably embedded into the binder layer 2 for forming the shape of the reflection layer on the base 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-observation-angle diffuse reflection sheet useful for various displays such as advertising signs and road traffic signs.

[0002]

2. Description of the Related Art Conventionally, retroreflective sheets are often used for traffic signs and the like from the viewpoint of good night visibility. However, the retroreflective sheeting aims at a narrow retroreflective effect such that the observation angle (the angle between the line connecting the light source and the retroreflective sheet and the line connecting the retroreflective sheet and the observation point) is about 0.2 degrees. The driver is located at an observable viewing angle in the distance and the presence of a sign etc. can be confirmed, but when approaching a short distance, the driver goes out of the observable observation angle and shows it on the sign There is a problem that it becomes difficult to recognize the information to be transmitted. Therefore, in addition to the lighting associated with the sign, it is necessary to arrange a powerful auxiliary light source at a location away from the sign to illuminate the sign, but from the viewpoint of energy efficiency, a wide recursion of visible observation angles is required. A reflective sheet has been desired.

Japanese Patent Application Laid-Open No. 7-281014 discloses a capsule lens type or exposed lens type retroreflective sheet using at least two types of glass beads having different refractive indices and expanding the observable observation angle to about 20 degrees. Has been proposed, and 10 CPL (candela / lux /
m2) or more, and at least partially shows 1 CPL or more in the observation angle range of 8 to 20 degrees. However, from the viewpoints of the observable observation angle and the total amount of reflected light, a reflection sheet having a wide observation angle and sufficient practical performance is desired as a reflection sheet for a sign on an expressway or the like.

[0004]

SUMMARY OF THE INVENTION In view of the problems of the prior art, it is an object of the present invention to provide a wide observation angle diffuse reflection sheet having good nighttime visibility for a driver of an automobile.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by forming a reflecting surface with a particle layer having a specific particle size distribution and shape on a support, the observable observation angle can be significantly increased. The inventors have found that the present invention has been completed.
That is, the structure of the present invention comprises, on a support, a binder layer, a layer of spherical or amorphous particles having an average particle size of 5 to 150 μm,
And a vapor deposition film layer in this order.

[0006] The present invention also includes a wide-observation-angle diffuse reflection sheet in which 50 to 90% of the particle diameter of the spherical or amorphous particles is buried in a binder layer.

The present invention further includes a wide-observation-angle diffuse reflection sheet, wherein the particles are alumina particles having a diffuse reflection surface.

[0008] The present invention also provides a support having, in this order, a binder layer, a layer of spherical or amorphous particles having an average particle diameter of 5 to 150 µm, a vapor-deposited film layer and a colorant layer on a support. Including a wide viewing angle diffuse reflection sheet for display, which is a feature.

[0009]

Embodiments of the present invention will be described below in detail. The wide observation angle reflection sheet of the present invention has a cross section shown in FIG.

As the support, any known film or sheet can be used as long as the material is mainly intended for outdoor use, but a biaxially stretched polyester film having a thickness of 25 to 75 μm or the like can be used. It is preferably used.

As the binder, any known material may be used as long as it is mainly used outdoors, and an acrylic adhesive or the like is preferably used.

As the shape of the fine particles forming the shape of the reflective layer on the support, spherical or amorphous particles are used. Further, the surface shape of the particles is preferably a shape having irregularities that cause diffuse reflection of incident light.

The average particle size of the fine particles forming the shape of the reflection layer is 5 to 150 μm, preferably 10 to 120 μm.

Further, in order to form the shape of the reflective layer on the support, the fine particles are partially exposed from the surface of the binder layer, and about 80% of the particle diameter of the fine particles is It is preferable to bury it in

As a sheet having an irregular particle layer together with a binder layer on a support, a particle size standard of # 180 to # 200
A water-resistant abrasive paper of 0 is also preferably used.

A known metal deposition film is formed as a reflective layer on the particle layer forming the shape of the reflective layer. As a material,
Silver, aluminum, nickel or the like is used. Silver is most desirable in terms of reflectivity, but aluminum is preferably used in a known method in view of the price at the present stage. The film thickness is 2
00 to 2000 angstroms, preferably 600 to
1200 Angstroms.

A transparent resin layer or a colored resin layer can be disposed on the reflection layer. Since this layer is directly exposed to the outside air, weather resistance and antifouling properties are particularly required. The resin is preferably an acrylic resin, a fluororesin, or the like, and as a means for ensuring durability, other than the addition of an ultraviolet absorber or a light stabilizer alone or in combination as necessary, a melamine resin or isocyanate resin A curing agent is added. In addition, the use of a transparent and weatherable perylene red, flavanthrone yellow, phthalocyanine green, or phthalocyanine blue pigment as the coloring agent provides excellent weather resistance to obtain a bright color reflection color due to the internal reflection effect of irradiation light. Can be.

[0018]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto.

[Example 1] (Preparation of test piece) A hexamethylene diisocyanate (HMDI) -based polymer was coated on a 75-μm-thick biaxially stretched polyester film with respect to 100 parts of an acrylic ester copolymer. An isocyanate cross-linking resin solution obtained by adding and mixing 15 parts of an isocyanate resin is applied so that the thickness after drying becomes 25 μm, and then dried at 100 ° C. for 5 minutes to form an acrylic urethane adhesive resin layer having a softening temperature of about 100 ° C. Provided. After uniformly dispersing glass spheres having an average particle diameter of 60 μm on the surface of the adhesive resin layer, the mixture is further heated at 160 ° C. for 5 minutes to soften the adhesive resin layer, so that the diameter of the glass spheres reaches the polyester film surface. About 80% were buried. A film that does not impair the shape of a glass sphere exposed to a melamine crosslinkable resin solution obtained by adding and blending 3 parts of a butylated melamine resin with 100 parts of an acrylate copolymer on the exposed surface of a buried glass sphere. Apply at a thickness of 150 ° C
And solidified for 10 minutes. Next, an aluminum vapor-deposited film layer having a thickness of 800 Å was provided on this surface. Further, a copolymer of acrylic acid ester 1 is formed on the surface of the deposited film.
100 parts of a hexamethylene diisocyanate-based polyisocyanate resin is added and mixed with 10 parts of an isocyanate cross-linking type adhesive resin solution so that the thickness after drying is 10 to 15 μm from the top of the glass sphere, and then dried at 100 ° C. Then, a test piece without a protective film was obtained. A 75 μm-thick polyester film prepared in advance was used as a support, and 100 parts of a colorless and transparent acrylic ester copolymer was coated with 1 part of a butylated melamine resin.
The melamine crosslinked resin solution added and mixed with 0 parts was applied so that the thickness after drying was 30 μm, and dried at 150 ° C. to obtain a protective film. The test piece without the protective film obtained in the above step and the surface of the protective film film obtained in the above step are laminated using a nip roll heated to 100 ° C. After lamination, the adhesive resin was left to stand at 40 ° C. for 3 days to cure the adhesive resin.
The 5 μm polyester film was peeled off to obtain a test piece (1).

Example 2 An acrylic acid ester to which a phthalocyanine-based green pigment was added in place of the “colorless and transparent resin solution of a melamine crosslinkable acrylic acid ester copolymer” in the process of Example 1 A test piece (2) was obtained in the same manner as in Example 1 except that a "melamine cross-linkable transparent green resin solution obtained by adding 10 parts of a butylated melamine resin to 100 parts of the copolymer was used."

Comparative Example 1 A capsule lens type retroreflective high-brightness reflective sheet (white) currently used for a road sign was used as a comparative test piece (1).

Comparative Example 2 A capsule lens type retroreflective high-brightness reflective sheet (green) currently used for a road sign was used as a comparative test piece (2).

[Examples 3 to 12] In the process of Example 1, "pulverized alumina particles having different average particle sizes" were used instead of "glass spheres". Specimens (3) to (12) were obtained in the same manner as in Example 1 except that the dry film thickness was adjusted so that the pulverized alumina was buried in the adhesive resin layer by about 80%.

[Examples 13 to 22] In the process of Example 1, "pulverized alumina particles having different average particle diameters" were used instead of "glass spheres". In the process, a dried film of an acrylic urethane adhesive resin layer was used. The thickness is adjusted so that the alumina pulverized material is buried in the adhesive resin layer by about 80%, and in the process of Example 1, "100 parts of a colorless and transparent acrylate copolymer is butylated melamine. 10 resin
Melamine crosslinkable resin solution prepared by adding 10 parts of a butylamine melamine resin to 100 parts of an acrylate copolymer to which a phthalocyanine-based green pigment is added instead of the Specimens (13) to (22) were obtained in the same manner as in Example 1 except that the “mold-type transparent green resin solution” was used.

[Measurement of Luminance] The test specimens (1) to (22) and the comparative test specimens (1) and (2) had a surface illuminance of 300 lux from an angle of 45 degrees with respect to the normal direction of the test specimen surface. Irradiation with white light was performed. Distance 10 on the normal to the surface of the specimen
The luminance at m was measured. The illuminance of the sample was measured using a photocell-type illuminometer (manufactured by Tokyo Optical Machine Co., Ltd.).
The unit is lux. The luminance is measured using a color luminance meter BM-5.
A (manufactured by Topcon Co., Ltd.). The unit is c
d / m2. The test results are shown in Tables 1 to 3.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

According to the present invention, even if the angle of incidence from the light source to the reflecting sheet and the angle of reflected light from the reflecting sheet to the observer are as wide as 45 degrees, a sufficient amount of light is visible to the observer. Is obtained. That is, it is possible to obtain a reflection sheet having a wide observable observation angle, high luminance, and excellent whiteness. Further, since the present invention does not require an air layer between the particle layer and the transparent or colored resin layer or the cover film layer, it does not require a honeycomb structure of a support and is excellent in adhesion.

[Brief description of the drawings]

FIG. 1 is a sectional view of a reflection sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support body 2 Binder layer 3 Spherical or irregular particle layer 4 Evaporation film layer 5 Resin layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Morimoto 2-5-26 Ogawa, Chiyogawa-cho, Kameoka-shi, Kyoto

Claims (4)

[Claims] 1. A binder layer having a mean particle size of 5 on a support.
A wide-observation-angle diffuse reflection sheet comprising a layer of spherical or amorphous particles having a size of 150 μm and a vapor-deposited film layer in this order. 2. The particle size of the spherical or amorphous particles is 50 to 9
The wide observation angle diffuse reflection sheet according to claim 1, wherein 0% is buried in the binder layer. 3. The wide-observation-angle diffuse reflection sheet according to claim 1, wherein the particles are amorphous alumina particles having a diffuse reflection surface. 4. A binder layer having a mean particle size of 5 on a support.
A wide-viewing-angle diffuse reflection sheet for display, comprising a layer of 150 μm spherical or amorphous particles, a deposited film layer and a colorant layer in this order.