JP2003268730A - Reflector for road marking and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflector for road marking and its manufacturing method enabling the reflector, used for road marking for travel at night, to have sufficient reflection brightness to light beams of headlights incident at a large angle and to cope exclusively with the condition of the road surface dry or submerged in water or to cope with both conditions. <P>SOLUTION: 1. The surfaces of beads relatively large in diameter are covered with an adhesive, and small-diameter glass beads metal-plated with aluminum or the like are embedded in the whole surface of the adhesive exposing semi-sphere portions. 2. The metal films of the exposed small-diameter glass bead semi-spheres are dissolved and separated using a basic solvent or the like to form a composite bead type omnidirectional uniform retroreflector. 3. The small-diameter beads with a refractive index of 1.5-1.93 are used as the retroreflector when the road surface is dry, while the small-diameter beads with a refractive index of 2.2 or more are used as the retroreflector when the road surface is submerged in water. 4. For all-weather use, the composite bead is covered with a transparent resin film to form one spherical surface, and the refractive index of the small-diameter beads is to be 2.2 or more. 5. In construction, the small-diameter bead exposed type ones are spread on a marking paint and embedded by the semi-sphere portions. The all-weather type ones can also be covered with transparent resin in place of the aforementioned method. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road marking reflector, which has a high retroreflective brightness particularly for a light ray incident at a large incident angle, and when the road surface is dry at night or when the road surface is submerged or both. On the other hand, the present invention relates to a road marking reflector having high reflection brightness.

[0002]

2. Description of the Related Art A material having retroreflectivity is used as a marking line for roads and a road marking. This is to scatter glass beads before the solidification of the paint applied to the road surface, immobilize it by embedding it for a hemisphere, and retroreflect the paint on the back surface of the glass beads as a reflective surface, with the purpose of being visible even at night. There is. However, if the marking surface is flooded in the rain,
Since the upper hemisphere part of the glass beads, which is responsible for the lens function, is submerged in water, the retroreflective function is impaired, and the visibility is remarkably deteriorated at night in rainy weather.

[0003]

The conventional reflector for road marking exhibits some visibility when the light from the headlight of a vehicle traveling at night has a small incident angle with respect to the road marking surface. Since the light from is incident on the marking surface at a large incident angle (usually 60 ° to 90 °), the retroreflection brightness is very weak. Moreover, in rainy weather, the retroreflective function is impaired due to the water film, which is dangerous because the markings cannot be visually recognized.
Therefore, the development of a material that can be retroreflected with high brightness even at a large incident angle and that functions even in rainy weather has been awaited.

[0004]

The present invention has been made in view of the above problems and solves the above problems by the following configurations and methods. 1. The surface of beads of relatively large diameter glass or plastics is covered with an adhesive, small diameter glass beads are spread over the entire surface of this adhesive, and a hemisphere is embedded to form a composite bead. A metal such as aluminum is plated to form a road marking reflector.

2. The small diameter glass beads are plated with metal such as aluminum (global plating) in advance,
For road marking, characterized by embedding a hemisphere of this small glass bead in the adhesive layer on the surface of a relatively large bead and dissolving and peeling only the metal plating on the exposed part of the small glass bead with a basic or acidic aqueous solution. A method of manufacturing a reflector is provided.

3. The surface of the composite bead is covered with a transparent resin to form a single spherical surface for use in both fine and rain, and a road marking reflector is formed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 and FIG. 2 are a schematic cross-sectional view and a partially enlarged view of a composite bead 1 which is a road marking reflector. The composite beads 1 are formed by adhering glass beads 2 made of glass or plastics having a relatively large diameter (inside and outside 500 μm) to glass beads 2 having a small diameter (inside and outside 50 μm). Composite beads 1 are transparent resin film 6
There are two types, one with and without a transparent resin film, FIG. 1 without a transparent resin film, and FIG. 2 with a transparent resin film.
The small-diameter glass beads 2 are embedded and fixed in the adhesive layer 4 by a hemisphere, and a reflective film 5 made of metal plating such as aluminum is provided on a surface in contact with the adhesive layer 4. Furthermore, two types are prepared for the type without a transparent resin film. That is, there are two types: a type used when the road surface is dry and a type used when the road surface is flooded. That is, composite beads using small glass beads having a refractive index of 1.5 to 1.93 (1.93 is optimal) are used for dry road surfaces, and composite beads using small glass beads having a refractive index of 2.2 or more for flooded road surfaces. Prepare two kinds of beads and use them in an appropriate combination. By doing this, it is possible to deal with either case of fine rain. Composite beads with a transparent resin film are used for both rain and rain. Although the refractive index of glass is limited, a high refractive index glass is used. Literature (Patent Publication Sho 6)
1-14095), the currently possible refractive index is up to 2.4. The mass-produced product has a refractive index of 2.25 (Asahi Techno Glass Co., Ltd.). In order to increase the relative refractive index between glass and resin, it is desirable that the resin film has a low refractive index. (As an example, there is one having a refractive index of 1.39 (Dainippon Paint Co., Ltd.).) The present invention is configured as described above.

Next, an example of a method for producing the composite beads is shown in a flow chart in FIG. First, small diameter glass beads are plated with aluminum (global plating). As a plating method, a dry plating method such as vacuum deposition, sputtering, or ion plating is used. Since the entire surface of the glass beads is plated in the plating step, it is necessary to devise a method of rolling and inverting the beads. Since the surface of the large-sized beads is covered with the adhesive having the required thickness, the ratio of the amount of the large-sized beads to the amount of the adhesive is accurately determined, and both are put in a container and stirred. The viscosity and the drying speed of the adhesive are important in manufacturing and the optimum values are experimentally found.
After the surface of the large-diameter beads is uniformly covered with the adhesive, a large amount of aluminum-plated (global-plated) small-diameter glass beads is put into a container and stirred until the individual composite spheres fall apart. This is taken out from the container, dried and baked. At this time, the remaining small diameter glass beads and the like are separated. Next, the composite beads are put into the container again and washed with an alkaline solution to dissolve and remove the aluminum plating on the exposed portion of the glass beads. If this is washed with water and dried, composite beads of a type without a transparent resin film are completed. The type with a transparent resin film is then soaked in a transparent resin solution, scooped with a net to cut off the liquid, and dried and baked in the air with hot air to form the resin film in a separated state. The present invention provides the manufacturing method as described above.

Next, the construction will be described. There are the following three construction methods. 1. Similar to the conventional construction method, the composite beads are sprinkled on the undried paint, and the hemisphere is embedded by applying pressure. FIG. 4 shows a sectional view after the construction. 2. A method of spraying composite beads on undried paint and then applying a transparent protective resin liquid. In this method, since the composite beads are embedded and fixed by the protective resin, the work of embedding the beads in the hemisphere as in the conventional coating is not essential.
FIG. 5 shows a cross-sectional view after the construction. 3. In this method, the composite beads are mixed in a transparent resin solution in advance and applied on the surface of the marking paint in such a manner that the underlying paint must be dry.

Next, the operation of the present invention will be described. Figure 6
Indicates retroreflection when small diameter glass beads having a refractive index n1 = 1.93 are used for a dry road surface. The variation of the exit angle of the glass beads having a refractive index of 1.93 will be described later,
The glass bead system shows the best retroreflection. If this is submerged, the relative refractive index n1 / n2 becomes 1.48 assuming that the refractive index of water is n2 = 1.333 and the retroreflection is drastically reduced. FIG. 7 is an explanatory diagram of retroreflection of high refractive index glass beads during flooding. In the figure, as an example, the refractive index of small glass beads n1 = 2.25, the refractive index of water n2
= 1.333, the relative refractive index n1 / n2 is 1.69, but due to development efforts, for example, n1 = 2.n.
When 4 is possible, the relative refractive index n1 / n2 becomes 1.80, and stronger retroreflection can be obtained. FIG. 8 is an explanatory diagram of retroreflection in the construction example of FIG. That is, when a transparent resin film is provided, it is retroreflected through the two resin layers after construction. In this case, if the transparent resin film 6 having a low refractive index is selected, the relative refractive index n1 / n3 can be increased. The figure shows that the relative refractive index is 1.71 when the small-diameter glass beads have a refractive index n1 = 2.4 and the transparent resin film n3 = 1.4.

FIG. 9 shows the relationship between the incident angle and the outgoing angle at the time of retroreflection. In this figure, the condition that the ray with the incident angle α is completely retroreflected is α = 2β, where β is the refraction angle. 10 °, 20 °, 30 °, 40 °, 50 to obtain the optimum refractive index
The refractive index is examined for each incident angle of 60 °. Refractive index n is n = sin α / sin β, β = α / 2 α = 10 ° n = sin 10 ° / sin 5 ° = 1.99 α = 20 ° n = sin 20 ° / sin 10 ° = 1.97 α = 30 ° n = sin 30 ° / sin 15 ° = 1.93 α = 40 ° n = sin 40 ° / sin 20 ° = 1.88 α = 50 ° n = sin 50 ° / sin 25 ° = 1.81 When α = 60 ° n = sin 60 ° / sin 30 ° = 1.73 In this way, the optimum value of the refractive index changes depending on the incident angle.
Next, the optimum refractive index as a whole is searched for among the above-mentioned refractive indexes. Since the commercially available beads have a refractive index of 1.93, the exit angle direction θ = 2 (2β−α) is investigated with respect to the above numerical values of 1.97, 1.93, and 1.88. From n = sin α / sin β β = arcsin (sin α / n) When n = 1.97 α = 10 ° β = 5.06 ° θ = 0.24 ° α = 20 ° β = 10.0 ° θ = 0 ° α = 30 ° β = 14.7 ° θ = −1.2 ° α = 40 ° β = 19.0 ° θ = −4.0 ° α = 50 ° β = 22.9 ° θ = −8. 4 ° α = 60 ° β = 26.1 ° θ = −15.6 ° n = 1.93 α = 10 ° β = 5.16 ° θ = 0.64 ° α = 20 ° β = 10. 2 ° θ = 0.8 ° α = 30 ° β = 15.0 ° θ = 0 ° α = 40 ° β = 19.5 ° θ = −2.0 ° α = 50 ° β = 23.4 ° θ = -6.4 ° α = 60 ° β = 26.7 ° θ = −13.2 ° In the case of n = 1.88 α = 10 ° β = 5.30 ° θ = 1.2 ° α = 20 ° β = 10.5 ° θ = 2.0 ° α = 30 ° β = 15.4 ° θ = 1.6 ° α = 40 ° β = 20.0 ° θ = 0 ° = 50 ° β = 24.0 ° θ = -4.0 ° α = 60 ° β = 27.4 ° θ = -10.4 ° Assuming a tolerance of deflection theta output angle within ± 1 ° and n
It turns out that the result is best when = 1.93.

FIG. 10 shows how the submerged reflector is retroreflected. As is clear from this figure, when the marking reflector is completely submerged in rainwater, there is a concern that the light from the headlight will be reflected considerably on the water surface and the retroreflected light will be weakened. This is clarified in the table shown in FIG. The values in this table are calculated assuming that there is no loss in the reflector.

The reflectance of the reflected light with respect to the incident light on the boundary surface between the two dielectric layers is obtained by the Fresnel equation.
When the incident light is divided into S-polarized light which is perpendicular to the electric field and P-polarized light which is parallel to the electric field, the reflectance rs of S-polarized light and the reflectance rp of P-polarized light are θs as an incident angle and θ2 as a refraction angle rs = (sin (θ1- θ2) / sin (θ1 + θ2)) ² rp = (tan (θ1−θ2) / tan (θ1 + θ2)) ² Refractive angle θ2 is sin θ2 = sin θ1 / 1.333 where r is the refractive index r = ( rs + rp) / 2 Transmittance t is t = 1-t Retroreflectance rr is rr = t ^{2 From} this table, for example, the retroreflection intensity of a headlight with an incident angle of 80 ° is about half that of a 60 ° incident angle. I understand.

[0014]

The present invention produces the following effects. Retroreflects almost uniformly and with high brightness for incident light from 1.0 ° to nearly 90 °. 2. We can supply the type for both dry and flooding, or both types. 3. Since the reflective film is a metal plating such as aluminum, the reflective brightness is much higher than the conventional white paint. 5. The marking paint color is maintained by controlling the spreading rate of the composite beads or the proportion of the composite beads in the clear resin solution. 6. The construction method is highly productive, not much different from conventional methods.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of the present invention and a partially enlarged view thereof (1)

FIG. 2 is a schematic sectional view of the present invention and a partially enlarged view thereof (2).

FIG. 3 is a flowchart of the manufacturing method of the present invention.

FIG. 4 is a cross-sectional view of a construction example using the present invention (1)

FIG. 5 is a sectional view of a construction example using the present invention (2)

FIG. 6 is an illustration of retroreflection when the road surface is dry.

FIG. 7 is an explanatory diagram of the recursion reflection when the road surface is submerged.

FIG. 8 is an illustration of retroreflection of composite beads with resin film.

FIG. 9 is a diagram showing a relationship between an incident angle and an outgoing angle of a light ray.

FIG. 10 is a view showing a cross section of a reflecting material and a behavior of a light beam during flooding.

FIG. 11 is a table of retroreflectance with respect to incident angles.

[Explanation of symbols]

1 composite beads 2 small diameter glass beads 3 large beads 4 Adhesive layer 5 Aluminum reflective film 6 Transparent resin film 7 Protective resin layer 8 paint layers 9 Road surface 10 Rainwater layer 11 Incident light and retroreflected light 12 reflected light

Claims (3)

[Claims] 1. A glass having a relatively large diameter, a surface of beads such as plastics, is covered with an adhesive, small glass beads are spread over the entire surface of the adhesive, and a hemisphere is embedded to form a composite bead. A reflective material for road marking, wherein the embedding hemisphere of the beads is plated with a metal such as aluminum. 2. The small glass beads are preliminarily plated with a metal such as aluminum (global plating), and the small glass beads are hemispherically embedded in the adhesive layer on the surface of the relatively large beads to expose the small glass beads. 2. The method for producing a road marking reflective material according to claim 1, wherein only the metal plating of a portion is dissolved and peeled off with a basic or acidic solution. 3. A reflective material for road marking, characterized in that the surface of the composite beads according to claim 1 is covered with a transparent resin to form one spherical surface.