JP2006163239A - Directional photoreflective material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflective material which causes retroreflection of only the light of incident angle within a prescribed range. <P>SOLUTION: The photoreflective material is constituted by providing a plurality of light opaque projecting parts on a base film and arranging a retroreflective material on the base film between the projecting parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a directional light reflecting material that retroreflects light incident at a predetermined angle, but blocks light incident at other angles.

  A louver film is a member in which a light transmission layer and a light blocking layer are alternately laminated. Light that is transmitted from a predetermined direction is blocked by the louver formed by the light blocking layer. The transmission angle can be regulated. Thus, light is transmitted at a certain angle but is not transmitted from a certain angle, and is used as a privacy filter or a screen image reflection prevention filter (see, for example, Patent Document 1).

  On the other hand, retroreflective sheets that retroreflect incident light toward a light source are well known and are used for road signs and the like (see, for example, Patent Document 2).

  By the way, in the conventional louver film, although consideration was given to blocking incident light, the directivity of reflected light was not considered at all, while the conventional retroreflective sheet considered directivity of reflected light. However, limiting the incident light is not taken into consideration, the angle between the incident light and the reflected light is limited, and no member retroreflects within the limit angle.

JP-A-6-305066 JP-A-6-347623

  An object of the present invention is to provide a directional light reflecting material that retroreflects light incident from a certain direction but shields light from other directions.

  In order to solve the above problems, according to the present invention, a plurality of light-impermeable convex portions are provided on a base film, and a retroreflective material is disposed on the base film between the convex portions. Material is provided.

  According to the present invention, by providing a light-impermeable convex portion on the base material, it is possible to block light incident at a convex angle other than a predetermined angle, and to limit the incident angle of light. By arranging the retroreflective material between the convex portions, only light incident at a predetermined angle can be retroreflected.

  The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing one embodiment of the light reflecting material of the present invention, and FIG. 2 is a top view of the light reflecting material. In the light reflecting material 1 of the present invention, a plurality of light-impermeable convex portions 3 are arranged on the base film 2, and the retroreflective material 4 is arranged on the base film 2 between the convex portions 3. Yes. The convex portion 3 serves as a louver of a so-called louver film, and allows only incident light within a predetermined angle (Cut off angle) of light emitted from the light source to enter, and is not within a predetermined angle range. The light is prevented from entering by the convex portion 3.

  In the light reflecting material 1, the material constituting the base film 2 is not particularly limited, and various resins such as a thermoplastic resin, a thermosetting resin, and an energy ray curable resin such as an ultraviolet ray can be used. . The base film 2 may be light transmissive or light impermeable. Specifically, the material constituting the base film 2 includes cellulose resins such as cellulose acetate butyrate and triacetyl cellulose, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polystyrene, polyurethane, and vinyl chloride. Examples thereof include highly transparent resins such as acrylic resins and polycarbonate resins, and light-impermeable resins obtained by adding pigments to the highly transparent resins.

  The convex portion 3 provided on the base film 2 is formed from a light-impermeable material that can absorb, scatter, or reflect light. Examples of such light-impermeable materials include (1) dark pigments and dark dyes such as black and gray, (2) metals such as aluminum and silver, (3) dark metal oxides, and (4) the above A highly transparent resin containing a dark pigment or a dark dye, or (4) a mat surface treated on the convex surface can be used.

  In this light reflecting material 1, the width of the base film 2 between the convex portions 3 is sufficiently larger than the width of the top of the convex portion 3 so that sufficient light enters the light reflecting material 1. Larger is preferred. Generally, the width of the base film 2 between the convex portions 3 is 10 μm to 500 μm, and the top width of the convex portions 3 is 5 μm to 100 μm. Moreover, the angle of the convex part 3 is the range of 0-45 degree normally. In addition, the angle of this convex part 3 means the angle of the convex part 3 with respect to the base film 2, and the case where the base film 2 and the convex part 3 are orthogonal is set to 0 degree. That is, the convex part 3 does not need to be orthogonal to the base film 2 as shown in FIG.

  The shape (cross-sectional shape) of the protrusion 3 is not particularly limited, and may be a trapezoid as shown in FIG. 1 or a rectangle as shown in FIG. The thickness and height of the projection 3 are not particularly limited and can be appropriately determined according to the purpose of use. Generally, the thickness is 0.01 mm to 1 mm, and the height is 0.01 mm to 2 mm.

  There is no particular limitation on the shape of the space on the base film 2 where the retroreflective material 4 is formed, which is formed between the plurality of convex portions 3, and the convex portions 3 are arranged in parallel to each other as shown in FIG. Spaces extending in parallel with each other may be formed, or as shown in FIG. 4, spaces may be formed on the base film 2 in a sea-island pattern. The shape of the sea-island pattern is not particularly limited, and may be, for example, a hexagon as shown in FIG. 4 or a circle.

  Moreover, the space on the base film 2 in which the retroreflective material 4 is disposed, which is formed between the plurality of convex portions 3, may be open as shown in FIG. 1, or light as shown in FIG. 5. You may seal by the panel 5 of a permeable material, or you may seal by joining convex parts and combining two louver films as shown in FIG.

  Furthermore, the space on the base film 2 in which the retroreflective material 4 is formed, which is formed between the plurality of convex portions 3, may be a gap or may be filled with a light transmissive resin. Examples of the light transmissive resin include cellulose resins such as cellulose acetate butyrate and triacetyl cellulose, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polystyrene, polyurethane, vinyl chloride, acrylic resin, and polycarbonate resin. Is mentioned.

  The retroreflective material 4 is not particularly limited as long as it exhibits retroreflectivity. The bead-shaped retroreflective material 4 as shown in FIGS. 1 to 6 or the cube-cornered retroreflective material as shown in FIG. Material 4 'can be used. As the bead-like retroreflective material, for example, glass beads having a diameter of 0.01 mm to 1.0 mm, capsule lens type beads, or beads made of titanium-containing silicon glass can be used. It is preferable to coat. As the cube-corner retroreflective material, 3M diamond grade can be used.

  In order to improve the retroreflectivity of the retroreflective material, it is preferable to dispose a reflective layer between the retroreflective material 4 and the base film 2. The reflective layer can be formed by aluminum deposition or reflective layer pasting, and the thickness is preferably 100 μm to 1 mm.

  The reflective material of the present invention can be manufactured using a general method for manufacturing a louver film. For example, after forming convex portions on the base film by a method such as injection molding, extrusion molding, embossing, etc., it can be manufactured by arranging and fixing the retroreflective material between the convex portions by diffusion scattering. .

Example 1
Using a urethane acrylate, a substrate having a straight groove structure having a convex portion having a top width of 0.08 mm, a bottom width of 0.1 mm, a depth of 0.2 mm, and a peak-to-peak pitch of 0.3 mm was manufactured. The substrate was matte black with paint spray. Glass beads (trade name Tungo: manufactured by 3M, refractive index: about 2.3) are sprinkled on the colored substrate, and the glass beads are rubbed into the groove of the substrate by hand. It removed and the reflective material of this invention was obtained.

Example 2
A reflective material of the present invention was prepared in the same manner as in Example 1 except that a glass bead was used with a trade name of Becko: 3M, and a refractive index of 1.9.

Example 3
The base material (non-colored base material) having a straight groove structure created in Example 1 is overlaid on the reflector manufactured in Example 1 with the convex portions aligned so that the groove directions are the same, as shown in FIG. A reflective material as shown in FIG.

Example 4
A reflective material of the present invention was prepared in the same manner as in Example 3 except that the trade name Becko: manufactured by 3M Corporation and a refractive index of 1.9 was used for the glass beads.

Example 5
The reflective material manufactured in Example 1 is overlaid with the straight groove structure base material (non-colored base material) created in Example 1 with the convex portions aligned so that the groove direction is 90 °, and reflected. The material was manufactured.

Example 6
A reflective material of the present invention was prepared in the same manner as in Example 5 except that the trade name Becko: manufactured by 3M Corporation and a refractive index of 1.9 was used for the glass beads.

Example 7
In the reflective material of Example 1, a highly reflective member (ESR, manufactured by 3M) was disposed between the beads and the base material to produce a reflective material.

Example 8
A reflective material of the present invention was prepared in the same manner as in Example 7 except that the trade name Becko: manufactured by 3M Company and a refractive index of 1.9 was used for the glass beads.

Comparative Example 1
A commercially available retroreflective product (diamond grade for road signs manufactured by 3M) was used.

Comparative Example 2
The glass bead uses the product name Becko: made by 3M, with a refractive index of about 1.9, and a UV curable resin (fluorinated acrylate, refractive index of 1.35) is poured into the groove of the reflective material, and it is cured by UV irradiation. A reflective material of the present invention was prepared in the same manner as in Example 1.

Comparative Example 3
A reflective material of the present invention was prepared in the same manner as in Comparative Example 2 except that the trade name Soda: manufactured by Toshinriko, having a refractive index of about 1.5 was used for the glass beads.

Comparative Example 4
A reflective material of the present invention was prepared in the same manner as in Example 1 except that the product name Soda: manufactured by Toshinriko, having a refractive index of about 1.5 was used for the glass beads.

Comparative Example 5
A reflective material of the present invention was prepared in the same manner as in Example 3 except that the product name Soda: manufactured by Toshinriko, having a refractive index of about 1.5 was used for the glass beads.

Comparative Example 6
A reflective material of the present invention was prepared in the same manner as in Example 5 except that the product name Soda: manufactured by Toshinriko, having a refractive index of about 1.5 was used for the glass beads.

Comparative Example 7
A reflective material of the present invention was prepared in the same manner as in Example 7 except that the product name Soda: manufactured by Toshinriko, having a refractive index of about 1.5 was used for the glass beads.

  About the above reflective material, the retroreflection property and the light blocking property were observed. The results are shown in Table 1 below.

  In Table 1, when retroreflection (Retro R) occurs with high brightness to the extent of a commercially available retroreflective product (diamond grade for road signs manufactured by 3M), Good, when it occurs, Medium, when not, Poor. Moreover, when the light shielding property (Cut Off) was as clear as a transmission type louver film (light control film manufactured by 3M), it was defined as Good, when it occurred, Medium, and when it did not, Poor.

  In Table 1, the reason why the light blocking property (Cut Off) is Medium in almost all of the samples is considered to be that some glass beads remain at the tip of the convex portion of the substrate. Therefore, when the glass beads are completely contained in the grooves between the convex portions, the light blocking property can be seen as designed.

  All the samples of Examples 1 to 8 showed retroreflection and light blocking properties (Cut Off angle of about 60 °), but the difference in refractive index between glass beads and air was 0.8 as in Comparative Examples 4 to 7. If it is smaller than ˜1.0, no retroreflection occurs. In addition, when encapsulated with an ultraviolet curable resin, as in Comparative Example 2 and Comparative Example 3, retroreflection does not occur if the difference in refractive index between the ultraviolet curable resin and the beads is less than 0.8 to 1.0. As in Comparative Example 1, when a commercially available retroreflective product (3M diamond grade for road signs) is used, the light blocking property is not shown.

It is sectional drawing which shows the structure of the light reflection material of this invention. It is a top view which shows the structure of the light reflection material of this invention. It is sectional drawing which shows the structure of the light reflection material of this invention. It is sectional drawing which shows the structure of the light reflection material of this invention. It is sectional drawing which shows the structure of the light reflection material of this invention. It is sectional drawing which shows the structure of the light reflection material of this invention. It is sectional drawing which shows the structure of the light reflection material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light reflecting material 2 Base film 3 Convex part 4 Retroreflective material

Claims (6)

  A light reflecting material obtained by providing a plurality of light-impermeable convex portions on a base film, and arranging a retroreflective material on the base film between the convex portions.   The light reflecting material according to claim 1, wherein the convex portions are arranged in parallel to each other, and the retroreflecting material is arranged in a band shape.   The light reflecting material according to claim 1, wherein the convex portions are arranged to form a predetermined shape, and the retroreflective material is arranged in a predetermined shape between the convex portions.   The light reflecting material according to claim 1, wherein a reflective layer is disposed between the retroreflecting material and the surface of the base film.   The light reflecting material according to any one of claims 1 to 4, wherein the retroreflecting material is formed by continuously arranging a plurality of beads.   The light reflecting material according to any one of claims 1 to 4, wherein the retroreflecting material is formed by continuously arranging a plurality of cube corner members.

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