JPH0254922B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention can be used in a wide range of applications such as various signs and clothing, in which at least a portion of the reflective surface has excellent light retroreflectivity. The present invention relates to a method of manufacturing a light reflector that can be produced.

(b) Conventional technology A light retroreflector with a single layer of glass spheres has been widely used as a light reflector for displaying traffic signs, etc., in order to improve visibility, especially at night. . These optical retroreflectors are roughly divided into two types in terms of structure: open type and closed type, but in both cases, the important point in terms of structure and manufacturing technology is how to make the reflected light return parallel to the incident light. Various innovations and improvements have been made and developments have been made.

That is, in the conventional open type optical retroreflector, a glass sphere with a medium to low refractive index of around 1.9 or less is used, and the front hemispherical surface of the glass sphere is exposed to the air. , and has a structure in which the glass globules are fixed with a bonding binder resin, and a reflective layer is provided directly on the rear hemispherical surface, and is buried in the support. This open type optical retroreflector has a structural feature that the front hemisphere of the glass sphere is exposed to the air, and the reflective layer is provided directly on the rear hemisphere of the glass sphere. Since there is no absorption or refraction of light by anything other than the glass sphere, the reflection brightness is high and the angular characteristics of reflection are excellent. If the part is coated with a substance with an optical refractive index such as transparent resin or rainwater, the light retroreflection function will be reduced, causing a significant decrease in brightness, and therefore, there will be disadvantages such as difficulty in providing a colored layer. are doing.

In addition, the closed type optical retroreflector has a refractive index
A glass sphere with a high refractive index of 2.0 or more is used, and a smooth transparent resin surface layer is formed on the front hemispherical surface of the glass sphere.
Similarly, on the rear hemispherical surface, there is a transparent resin binder layer in the shape of a hemispherical shell concentric with the center of the glass globule, and a reflective layer is provided behind the transparent resin binder layer to provide optical retroreflection ability. ing. This closed type light retroreflector can be easily given any color by coloring the transparent resin surface layer or the transparent resin binder layer, but on the other hand, the front and rear hemispheres of the glass spheres are Due to the presence of the transparent resin surface layer and the transparent resin binder layer, the light transmission loss is extremely large and the brightness value is low.

In response, the present inventor has developed an optical retroreflector with a novel structure that takes advantage of the respective features of the open type optical retroreflector and the closed type optical retroreflector as described above, and compensates for the drawbacks. , a high refractive index glass sphere with a diameter of 500μ or less and a refractive index of 2.0 or more is buried in a fixed binder resin layer held on a support with a burial rate of 40 to 80% of the diameter, and the rear buried spherical surface of the glass sphere is buried. He invented an optical retroreflector in which a direct reflective layer was provided on the front exposed spherical surface, and a transparent resin coating layer was formed on a concentric elliptical hemispherical shell so as to cover the exposed hemispherical surface on the front exposed spherical surface side (Japanese Patent Laid-Open No. 60-64302).
Publication No.). In this light retroreflector, a reflective layer is provided directly on the rear buried spherical surface of the glass sphere, resulting in low light transmission loss and high reflective brightness.Also, by coloring the transparent resin coating layer, it is possible to create any desired color. can be easily colored. Moreover, the colorless or colored transparent resin coating layer provided on the exposed hemisphere side of the front part of the glass bulb may be formed on the entire surface or may be formed partially by drawing letters, designs, etc., and the transparent resin coating layer is formed. An area with a diffuse reflection ability caused by the high refractive index of the glass sphere and the position of the reflective layer, and a part with a transparent resin coating layer that has an optical retroreflection ability, make it extremely unique. A light reflector having excellent reflection characteristics can be obtained.

However, during the manufacturing process of the above-mentioned light reflector, especially when providing a transparent resin coating layer on the exposed hemisphere side of the front part of the glass bulb, a transparent resin solution is applied to the surface where the front part of the glass bulb is exposed to a thickness of the axis resin coating. Ultra-thin thickness of 0.01
The coating is applied so that the film has a thickness of ~5μ, but in this case, the plastic film that is the support for the light reflector, the expansion and contraction of the fabric, unevenness, etc., tend to cause streaks and scratches on the coating, which is critical to the reflective performance, appearance, etc. It may have a negative impact.

(c) Problems to be Solved by the Invention The present invention provides a method in which 40 to 80% of the diameter of high refractive index glass globules having a refractive index of 2.0 or more are embedded in a fixed binder resin layer fixed to the above-mentioned support. A reflective layer is provided directly on the rear buried hemispherical surface of the small sphere, and a transparent resin coating layer in the shape of a concentric elliptical hemispherical shell is provided on at least a portion of the front exposed hemispherical surface so as to cover the front exposed hemispherical surface of the glass small sphere. The present invention aims to provide a manufacturing method that allows the transparent resin coating layer of the formed light reflector to be easily formed without causing defects such as streaks and blurring.

(d) Means and effects for solving the problems The present invention forms a transparent resin coating layer that hardens at a temperature higher than the softening point of the polyethylene film on at least a part of the surface of the polyethylene film laminated to the base film. After that, a large number of high refractive index glass spheres with a diameter of 500μ or less and a refractive index of 2.0 or more are sprinkled on the entire surface in a single layer, and the glass spheres are heated near the temperature at which the transparent resin coating layer hardens. The transparent resin coating layer is temporarily buried at a burial rate of 20 to 60% of the diameter, and the transparent resin coating layer is cured. Next, a reflective layer is formed on the non-buried hemispherical surface of the glass sphere, and the back side of the reflective layer is fixed. This method of manufacturing a light reflector is characterized in that it is fixed to a support via a binder resin layer, and then the base film and the polyethylene film laminated thereto are peeled off.

FIG. 1 is a schematic cross-sectional view showing a state immediately before completion of an example of a light reflector obtained by the present invention in which a transparent resin coating layer is partially provided. 3 is a support, 3 is a fixed binder resin layer, 4 is a reflective layer, 5 is a transparent resin coating layer, and 6 is an adhesive layer. FIG. 2 is a cross-sectional view schematically showing a state in which glass beads are being heated after being scattered when manufacturing the light reflector shown in FIG. 1 according to the present invention.

That is, a polyethylene film 8 laminated on a base film 7 such as a polyester film.
A solution of a colorless or colored transparent resin that hardens at a temperature higher than the softening point of the polyethylene film is applied to the entire surface of the polyethylene film, or to a portion of the surface to form letters, designs, etc., so that the thickness of the transparent resin coating layer is 0.01 mm.
After coating or gravure printing with a coater etc. to a uniform thickness within the range of ~5μ, heating and drying at 120℃ or less, a large number of glass beads 1 are coated on the entire surface.
is sprayed in a single layer and heated to 140 to 170°C, which is higher than the softening point of the polyethylene film 8, to temporarily embed the glass beads 1 together with the softened transparent resin coating layer 5 in the polyethylene film 8, and at the same time After curing the resin coating layer 5, a reflective layer 4 is formed on the exposed hemispherical surface of the glass sphere 1, and a fixed binder resin layer 3 is laminated on the back side of the reflective layer 4 to a predetermined thickness. , plastic film,
The polyethylene film 7, which is fixed to a support 2 such as cloth by adhesion or fusion, and in which the glass beads 1 are temporarily embedded, is then peeled off together with the base film to obtain the light reflector shown in FIG. 1.

In the present invention, the glass beads 1 used have a diameter of 500 μm or less and a refractive index of 2.0 or more, as described above.
If the diameter exceeds 500μ, it will not be possible to obtain a thin, flexible, usable light reflector;
A thickness of about 150μ is preferable. Further, if the refractive index is less than 2.0, a light reflector having an excellent light retroreflection ability cannot be obtained in the structure of the light reflector targeted by the present invention. The degree of temporary embedding of the glass sphere 1 into the polyethylene film 8 and/or the transparent resin coating layer 5 is 20 to 60 degrees of the diameter of the glass sphere 1, as in the case of conventionally known general light retroreflectors. %
Around 50% is most preferable from the viewpoint of fixation of the glass sphere 1 and reflection effect.

The transparent resin coating layer 5 formed on at least a part of the surface of the polyethylene film 8 laminated on the base film 7 is formed by heating it to 140 to 170°C, which is higher than the softening point of the polyethylene film 8. The glass sphere 1 is softened to the extent that it can be buried at a predetermined burial rate, and the hardening reaction gradually progresses, so that after a predetermined period of time, it no longer flows and deforms, and the resin has good releasability to polyethylene film. Preferably, for example, a mixture of polyurethane resin and hexamethylene diisocyanate is preferable, and the solution is a solution of an organic solvent such as toluene, optionally colored with a pigment, etc., and coated with a coater or the like, or by means such as gravure printing. Apply by. The amount of molten transparent resin solution is
The thickness of the transparent resin coating layer to be formed may be set to be about 0.01 to 5 μm, which is necessary and sufficient to impart optical retroreflection ability, and which provides uniformity of film thickness, strength, etc. . Furthermore, it is desirable to adjust the viscosity, heating temperature, etc. of the transparent resin so that the transparent resin coating layer can be embedded in a state that covers the hemispherical surface of the glass sphere in the form of a concentric elliptical hemispherical shell.

Next, the reflective layer 4 is formed directly on the hemispherical surface of the glass sphere 1 by vapor depositing or plating a thin film of metal such as aluminum, or by applying a resin liquid mixed with a light reflective substance such as aluminum powder. can be formed.

As the fixed binder resin formed on the back side of the reflective layer 4, various synthetic resins such as acrylic resins and urethane resins can be used, and may be appropriately selected from the viewpoint of flexibility depending on the application. .

The support 2 to be fixed via the fixing binder resin layer 3 may be any material suitable for the purpose, such as woven or knitted fabrics, nonwoven fabrics, sheet-like materials such as films, threads, ropes, or other molded materials such as metals or synthetic resins. Can be applied to object surfaces.

In the present invention, the formation of a transparent resin coating layer on the front exposed hemisphere of the glass sphere is performed by expanding and contracting the support.
Rather than doing this in the final process after the exposed hemispherical surface of the front of the glass bulb is completed, where streaks and scratches are likely to occur due to unevenness, etc., transparent resin is applied in advance to the surface of a stable, smooth polyethylene film with low elasticity. It forms a coating layer, which eliminates defects such as streaks and blurring during coating of transparent resin solution or gravure printing, and improves appearance and appearance.
A light reflector with excellent performance can be easily obtained.

In the light reflector obtained in the present invention, a transparent resin coating layer is laminated on the entire surface or part of the exposed hemisphere side of the front part of the glass bulb, and the portion where the transparent resin coating layer is laminated is exposed to light rays. The refraction at the transparent resin coating layer and the refraction at the glass sphere provide excellent retroreflectivity, and the exposed front hemisphere of the glass sphere without the transparent resin coating layer is , the light rays are refracted only by glass spheres with a high refractive index,
It has excellent diffuse reflection performance and wide-angle visibility. In addition, if there is a mixture of the part where the transparent resin coating layer is formed and the part where the front hemispherical surface of the glass bulb is exposed, transparent resin can be added to any part including both parts as necessary. It is also possible to provide a layer, in which case the thickness of the transparent resin coating layer increases in areas that already have optical retroreflectivity, weakening the optical retroreflection ability, and conversely, in areas where a new transparent resin coating layer is formed. By being given optical retroreflectivity, a new reflection pattern can be created.

FIG. 3 is an explanatory diagram schematically showing a mechanism exhibiting the above-mentioned reflection characteristics in a light reflector obtained by the present invention. FIG. 3A shows the light reflection situation at the exposed hemisphere of the front part of the glass bulb where the transparent resin coating layer 5 is not laminated, and FIG. 3B shows the light reflection situation at the portion where the transparent resin coating layer 5 is laminated. Indicates the light reflection situation.
In Fig. 3A, since the glass sphere 1 has a high refractive index, the incident light ray Ra is greatly refracted, the reflection point P is shifted, and the reflected light ray Rb is not parallel to the incident light ray Ra, but becomes diffused light and is reflected. It exhibits a bright silvery white color, which is the hue of layer 4. On the other hand, the transparent resin coating layer 5
is formed on the front hemisphere side of the glass sphere 1,
As shown in FIG. 3B, the incident light ray Ra is refracted by the transparent resin coating layer 5, and then refracted again by the glass sphere 1, and the reflection point is determined by the combination of the refractive index and thickness of each of these two refraction steps. P is the reflected ray
When Rb exits into the air, it is formed at a position parallel to the incident light ray Ra, giving it optical retroreflectivity.

(e) Examples Example 1 A transparent resin solution having the following composition was applied to the entire surface of a 40μ thick polyethylene film laminated to a 75μ thick polyethylene film so that the average thickness of the transparent resin coating layer was 2μ. 2 at 120℃
It is dried by heating for minutes to form a transparent resin coating layer with slight tackiness, and then has a diameter of 80μ and a refractive index.
2.25 high refractive index glass spheres are scattered and adhered in a single layer on the transparent resin coating layer, and heated at 160°C for 2 minutes to form a softened transparent resin coating layer and a sufficiently softened polyethylene film together with the glass globules. The glass globules were immersed in the glass and hardened to 50% of their diameter.

Non-yellowing polyurethane resin (XS-125: manufactured by Dainippon Ink & Chemicals Co., Ltd.) 80.0% by weight Hexamethylene diisocyanate 4.0% by weight Toluene 16.0% by weight Next, a layer of approximately 100% thick was applied to the exposed hemispherical surface of the glass sphere.
A thin aluminum layer of 800 Å is deposited to form a reflective layer, and an acrylic-urethane resin is applied as a fixed binder resin on the top surface to a thickness of 60 μm. A light reflector was obtained by adhering and fixing with a polyester adhesive having a thickness of about 10 μm, and then peeling off the polyester-polyethylene laminate film.

In the obtained light reflector, the transparent resin coating on the light incident surface covers the glass sphere in the shape of a gentle concentric elliptical hemispherical shell, and there are no streaks or scratches, and the transparent resin coating Due to the refraction in the layer, the refraction in the high refractive index glass sphere, and the reflective layer at the rear of the glass sphere, the incident light was reflected retroactively and had excellent reflection performance.

Example 2 A blue colored transparent resin solution having the following composition was used on a 40μ thick polyethylene film laminated to a 75μ thick polyester film.
The engraved part of the gravure roll is coated with a floral pattern with a film thickness of 2μ using a gravure roll printing machine.
The printed area is dried by heating at 120℃ for 2 minutes to form a colored transparent resin film with slight tackiness, and the surface of the polyethylene film in the non-printed area is softened, and then the entire surface including the printed and non-printed areas is coated. High refractive index glass globules with a diameter of 80μ and a refractive index of 2.25 were evenly distributed and deposited on the monolayer, followed by 160μ
℃ for 2 minutes to harden the transparent resin coating layer on the printed area, and leave the non-printed area as it is to increase the embedment rate of the glass sphere in the polyethylene film by 50%.
% was temporarily buried.

Non-yellowing polyurethane resin (XS-125: manufactured by Dainippon Ink and Chemicals Co., Ltd.) 74.0% by weight Phthalocyanine blue pigment (Fast Gen
NK: Manufactured by Dainippon Ink & Chemicals Co., Ltd.) 6.2% by weight Hexamethylene diisocyanate 4.0% by weight Toluene 15.8% by weight Next, apply a layer to the exposed hemispherical surface of the glass pellet to a thickness of approx.
A thin aluminum layer of 800 Å is vapor-deposited to form a reflective layer, and an acrylic-urethane resin is applied as a fixed binder resin on the top surface to a thickness of 60 μm. A light reflector was obtained by adhering and fixing with a polyester adhesive having a thickness of about 10 μm, and then peeling off the polyester-polyethylene laminate film.

In the obtained light reflector, the floral print part is colored blue, and the blue transparent resin coating layer on the light incident surface covers the glass sphere in a gentle concentric elliptical hemispherical shell shape, eliminating streaks and scratches. In addition, the incident light is retroreflected due to the refraction in the transparent resin coating layer, the refraction in the high refractive index glass sphere, and the reflective layer at the rear of the glass sphere, and the non-printed area has a high light incidence surface. It is the front hemispherical surface of the refractive index glass sphere, and due to the refraction of the glass sphere alone, it exhibits a silvery white color due to diffuse reflection, and has a blue flower pattern on a white background with good contrast under nighttime illumination. It was a light reflector that made it visible.

Furthermore, a transparent resin solution with the following composition was applied to the entire surface of the light reflector obtained above, and the average thickness of the transparent resin coating was 2μ, and the coating was applied to the apex of the glass globules exposed in the non-printed area. It was coated to a thickness of 0.1 μm and heat treated at 130° C. for 3 minutes to form a transparent resin coating layer in the shape of a concentric elliptical hemispherical shell on the glass sphere.

Methacrylic acid alkyl ester resin (XS
-732: Manufactured by Dainippon Ink & Chemicals Co., Ltd.)
74.1% by weight Melamine curing agent (US34B: Hitachi Chemical Polymer
Co., Ltd.) 3.7% by weight Toluene 22.2% by weight In the obtained light reflector, transparent resin is further laminated on the top surface of the already printed floral pattern part, so the refraction state changes and light is reflected back. On the contrary, a transparent resin coating layer in the shape of an appropriate concentric elliptical hemispherical shell is formed on the unprinted area, giving it retroreflectivity and making it difficult to reflect under nighttime irradiation light. In this case, the blue floral pattern became dark and dark, and the plain white part became a pure white light reflector due to retroreflection.

(f) Effects of the Invention The present invention has the above-mentioned configuration, in which a large number of high refractive index glass spheres with a diameter of 500 μm or less and a refractive index of 2.0 or more are fixed to a binder resin layer in a single layer and are formed in a single layer with a diameter of 40 to 80 μm.
%, a reflective layer is provided directly on the buried rear hemisphere side of each glass globule, and a transparent resin coating layer is formed on at least a part of the front hemisphere side. When manufacturing, in particular, the transparent resin coating layer is formed in advance on a stable and smooth polyethylene film with little expansion and contraction,
Next, by scattering and burying the glass beads, a uniform transparent resin coating layer can be easily formed without causing defects such as streaks and scratches.
In the obtained light reflector, a transparent resin coating layer is formed to cover the glass sphere in a substantially concentric elliptical hemispherical shell shape, and exhibits an excellent appearance and light retroreflection performance. The light retroreflector can be formed with any design and color, and the light reflector can be easily manufactured for a wide variety of uses such as various signs and clothing.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of a light reflector obtained by the present invention in a state immediately before completion, and FIG.
FIG. 3 is a schematic cross-sectional view showing a state in which glass beads are being heated after being scattered when manufacturing the light reflector illustrated in the figure, and FIG. 3 is an explanatory diagram of the reflection mechanism of the light reflector obtained by the present invention. . DESCRIPTION OF SYMBOLS 1...Glass sphere, 2...Support, 3...Fixed binder resin layer, 4...Reflection layer, 5...Transparent resin coating layer, 7
...Base film, 8...Polyethylene film.

Claims (1)

[Claims] 1. After forming a transparent resin coating layer that hardens at a temperature higher than the softening point of the polyethylene film on at least part of the surface of the polyethylene film laminated to the base film, a large number of layers with a diameter of 500μ or less and a refractive index of 2.0 or more are formed on the entire surface. A single layer of high refractive index glass spheres of 100 mL is distributed, and the glass globules are heated to a temperature near the temperature at which the transparent resin coating layer hardens.
Temporary burial is performed at a burial rate of 20 to 60%, and the transparent resin coating layer is cured. Next, a reflective layer is formed on the non-buried hemispherical surface of the glass sphere, and the back side of the reflective layer is fixed with a binder resin. A method for manufacturing a light reflector, which comprises fixing the base film to a support via a layer, and then peeling off the base film and the polyethylene film laminated thereto.