JP2001048586A - Light reflecting glass bead and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light reflecting glass bead suitable for a road marking coating film and a reflecting tape for traffic-control signs, excellent in retroreflection characteristics and diffuse reflectance characteristics, having excellent visibility even in the rain at night. SOLUTION: This light reflecting glass bead 10 comprises a glass bead 11 having <=1.6 refractive index whose surface is coated with a transparent or translucent coating film having >=2.6 refractive index. Soda-lime glass having 20-400 μm particle diameter is used as the glass bead 11 having <=1.6 refractive index. A rutile type titanium oxide 12 having 500-5,000 Å film thickness is preferable as the transparent or translucent coating film having >=2.6 refractive index. The glass bead having a high refractive index is made by the rutile type titanium oxide coating film 12 and the visual check of light Lout of retroreflection is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-reflective glass which is incorporated in a sign coating film for a road surface, an airport runway, etc., and various traffic-related road-related members such as a reflective tape for a traffic sign, a reflective sheet and a reflective cloth. The present invention relates to beads and a method for producing the beads.

[0002]

2. Description of the Related Art As light reflecting glass beads for road marking paint, spherical soda-lime glass beads having a refractive index of about 1.5 and made of Na ₂ O—CaO—SiO ₂ are widely used. Soda-lime glass beads improve visibility by utilizing the retroreflective effect of light, which is a characteristic of transparent microsphere lenses. When the road marking film 2 in which the soda-lime glass beads 1 are dispersed is irradiated with a vehicle light at night in fine weather, the incident light Lin _{in the} soda-lime glass beads 1 as shown in FIG. The light is repeatedly refracted and reflected and emitted as retroreflected light _Lout . The driver and passenger can visually recognize the road marking the angle between the road surface by a large retroreflected light L _out. In the road surface display using the soda-lime glass beads 1, visibility at night in rainy weather deteriorates. That is,
In the nighttime of rainy weather, the water film 3 accumulates on the road marking film 2 as shown in FIG. The refractive index of the water film 3 is as large as about 1.3 as compared with the refractive index of air (about 1.0), and the difference between the refractive index of the soda-lime glass beads 1 (about 1.5) is small. Therefore, the angle of the retroreflected light _Lout generated by refraction / reflection of the incident light Lin _{in the} soda-lime glass beads 1 becomes small with _respect to the road surface, and it is difficult for the driver or the passenger to enter the field of view.

[0003] The visibility at night in rainy weather is soda-lime glass.
High refractive index glass beads with a larger refractive index than Bead 1
Can be improved by using High refractive index glass
The road marking film 2 in which the phase 4 is dispersed is illuminated by the vehicle light.
When it is shot, the angle between it and the road surface as shown in FIG.
Retroreflected light L that is large and easy to see_out Occurs. Road surface
Even if the water film 3 is formed on the marking coating film 2, a high refractive index glass
Since the refractive index difference between the beads 4 and the water film 3 is large,
(B) As shown in FIG._out Angle between
The degree is kept large. The driver or passenger must have a large angle
Retroreflection light L _out You can see the road markings. High
BaO—TiO 2 is used as the refractive index glass beads 4._Two -S
iO_Two System (refractive index about 1.9), BaO-TiO_Two -Zn
O type (refractive index: about 2.2) and the like are known.

Light reflective glass beads used for reflective tapes for traffic signs and the like are required to have a small particle size and to have stronger retroreflective characteristics. In order to obtain higher retroreflection characteristics using light-reflective glass beads having a small particle diameter, an aluminum vapor-deposited film 7 provided on a base cloth 5 with an adhesive layer 6 interposed therebetween is used.
A method of laminating a transparent resin layer 9 in which light-reflective glass beads 8 are dispersed (FIG. 3A) or a method of aligning and disposing light-reflective glass beads 8 having an aluminum vapor-deposited film 7 formed on a half surface thereof (FIG. 3A). FIG. 3b) and the like are employed. When the light reflective glass beads 8 is irradiated with vehicle light, the incident light L _in is refracted incident on the light reflective glass beads 8, it is totally reflected by the aluminum deposited layer 7, and is emitted as retroreflected light L _out . The retroreflective properties of the light reflecting glass beads 8 are further improved by the combined use of the aluminum vapor-deposited film 7, but they do not have the scattering and reflecting properties found in aluminum flake pigments. Moreover, nor the incident light L _in is completely retro-reflected light L _out. For example, most of the light incident on the periphery of the light reflecting glass beads 8 tends to have a slightly larger reflection angle. The amount of change in the reflection angle becomes greater at night in rainy weather when a water film is formed, and visibility at night in rainy weather deteriorates. Moreover, the light reflecting glass beads 8 are not arranged on a tape, a sheet, a cloth or the like provided with the aluminum vapor-deposited film 7, but are dispersed in a paint and then applied to the surface of a member having various shapes.・ It is only dried. Therefore, in the case of glass beads having anisotropy, such as the light reflecting glass beads 8 having the aluminum vapor-deposited film 7 provided on the half surface, the visibility may be extremely poor depending on the observation angle.

[0005]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem, and has been proposed by covering the surface of glass beads with a transparent or translucent interference film having a high refractive index. It is an object of the present invention to provide a light reflecting glass bead having excellent retroreflection characteristics and scattered reflection characteristics, exhibiting an optical interference effect, and having extremely high visibility regardless of whether it is sunny or rainy.

[0006]

In order to achieve the object, the light-reflecting glass beads of the present invention have a surface of glass beads having a refractive index of 1.6 or less formed of a transparent or translucent film having a refractive index of 2.6 or more. It is characterized by being covered. Refractive index 1.6
As the following glass beads, for example, a particle size of 20 to 14
00 μm soda-lime glass is used. Refractive index 2.
As a transparent or translucent film of 6 or more, a film thickness of 50 to 50
A rutile type titanium oxide of 00 ° is preferred. The light-reflecting glass beads are coated with metallic titanium on a surface of soda-lime glass having a refractive index of 1.6 or less, and then heated to 550 to 650 ° C. in an air atmosphere to oxidize the metallic titanium to rutile-type titanium oxide. It is manufactured by

[0007]

In the conventional light reflecting glass beads, transparent and true spherical particles having a refractive index as large as possible are required to obtain higher retroreflection characteristics. However, with regard to the refractive index, the heavy-flint glass for optics is 1.7, and the 50% Pb-50% B ₂ O ₂ glass having the largest refractive index is only 1.9, and the refractive index is 2.2. No more glass beads are found. Examples of transparent high refractive index materials include cadmium sulfide (refractive index 2.5), zinc selenide ((refractive index 2.6), lead oxide (refractive index 2.6), and cadmium telluride (refractive index 2.7). ), Arsenic trisulfide (refractive index 2.7), lead sulfide (refractive index 3.9), etc., but none of them can be used because they contain toxic metals. .6), silicon carbide (refractive index 2.7), silicon (refractive index 3.5), etc. cannot be processed into a true spherical shape due to the melting point and the crystal structure.

Accordingly, the present inventor has studied using the true spherical shape of the glass beads to coat the surface of the glass beads with rutile-type titanium oxide that is transparent and has a very large refractive index. Rutile type titanium oxide does not contain harmful metals,
Does not adversely affect the environment. The rutile-type titanium oxide film 12 formed on the surface of the glass beads 11 exhibits an optical effect like a combination lens of a camera as shown in FIG. 4, and has a retroreflective property superior to that of a conventional ultra-high refractive index material. Is applied to the glass beads 11. Since the rutile-type titanium oxide film 12 itself has a refractive index twice as large as the refractive index of water, it exhibits excellent visibility even at night in rainy weather. In addition, the smaller the refractive index of the glass beads 11 serving as the nucleus is 1.6 or less, the more the scattered reflected light _Lref is generated at the interface between the glass beads 11 and the rutile type titanium oxide film 12,
A scattering reflection characteristic and an optical interference effect are also exhibited.

The light reflecting glass beads 10 in which the rutile type titanium oxide film 12 is formed on the surface of the glass beads 11 are excellent in retroreflection characteristics, scattering reflection characteristics and optical interference, and are dispersed in a paint. By simply applying and drying the surface of various members, a sign surface exhibiting excellent visibility can be obtained. That is, the aluminum deposition film 7 is used as the base cloth 5 (FIG. 3).
a) and light-reflective glass beads 8 (FIG. 3b), it is not necessary to provide the transparent resin layer 9 in which the light-reflective glass beads 10 are dispersed as shown in FIG. Since the marking surface is obtained, the construction work is also facilitated. Of course, the aluminum deposited film 7 may be provided on the base cloth 5, or a half surface of the light reflecting glass beads 10 may be covered with the aluminum deposited film 7. When the aluminum vapor-deposited film 7 is used in combination, a reflection tape for traffic signs with further improved retroreflection characteristics and scattering reflection characteristics is produced.

The rutile type titanium oxide film 12 provided on the surface of the glass beads 11 has an optical interference effect. The interference color is adjusted to various colors depending on the film thickness, crystal structure, smoothness of the outermost surface, components added to the rutile-type titanium oxide film 12, and the like of the rutile-type titanium oxide film 12. In this respect, when a colored portion such as yellow, red, blue, green, etc. other than white is formed with a conventional reflective tape for traffic signs, a paint in which a colored pigment and light reflecting glass beads are mixed is used in part. When the light reflecting glass beads are concealed by the coloring pigment, the intensity of the retroreflected light decreases. Although beads made of colored glass and glass beads coated with colored paint are also being studied, incident light is absorbed by the colored glass to cause a decrease in the intensity of retroreflected light, or insufficient weather resistance of the colored paint. There was a problem. On the other hand, the light-reflective glass beads 10 according to the present invention exhibit an interference color due to the optical interference effect, so that the amount of the coloring pigment required for a predetermined color tone can be reduced. Therefore, the light reflecting glass beads 10 are hard to be concealed, and a decrease in the intensity of retroreflected light or scattered reflected light is suppressed.

The rutile type titanium oxide film 12 has a thickness of 50 to 5
It is almost uniformly provided on the surface of the glass beads 11 with a thickness of 000 °. A method for forming a rutile-type titanium oxide thin film on the surface of mica has been conventionally known, and is actually commercially available as a pearl mica pigment. In a conventional typical thin film forming method, an aqueous solution of an inorganic salt of titanium (for example, titanyl sulfate) is hydrolyzed in the presence of mica to precipitate hydrated titanium dioxide on the surface of mica, and then 800 to 800 μm in an air atmosphere. Heating to 900 ° C. causes a phase transition to rutile type titanium oxide. In this method, a rutile-type titanium oxide film having a thickness of 50 to several thousand angstroms is formed on the surface of mica. However, when glass beads whose melting point does not reach 800 ° C. are used as nuclei, 800 beads necessary for phase transition are used.
The conventional method for forming a thin film cannot be applied because heating at up to 900 ° C. is not possible.

Therefore, the present inventor has proposed that the glass beads 11
Form a thin and uniform titanium metal film on the surface
For oxidizing titanium to rutile type titanium oxide film 12
The law was considered. Ultra-thin metal titanium and glass beads 1
When formed on the surface of No. 1, the melting point of glass beads 11 is reached
Oxidation of titanium metal at low temperature and short heating
Proceed well. Specifically, the surface of the glass beads 11
Metal thin film having a thickness of 47 to 4700 ° formed on the substrate
Is heated to 550-650 ° C. for about 1 hour in the air atmosphere.
A color of 50-5000mm in interference color
It becomes the rutile type titanium oxide film 12. Thin metal titanium thin
The reason why the film easily becomes the rutile type titanium oxide film 12 is as follows.
It is inferred as follows. Metallic titanium thin film thickness 47-4
700 ° is 25 to 25 from the atomic diameter of Ti (about 2 °).
It is a layer in which 00 atoms are stacked.
The oxidation reaction sufficiently proceeds even by heating. Reaction product
The titanium oxide contains Si,
Rutile is formed by an element such as Mg or Na. Also,
Na in glass beads 11 reacts with metallic titanium during heating
And Na_x Ti _y O_z Is generated at the interface, and glass beads 1
Adhesion of rutile type titanium oxide to 1 is improved.

A metal titanium thin film having a thickness of 47 to 4700 ° can be formed on the surface of the glass beads 11 by various dry processes such as vacuum deposition, CVD, sputtering, and ion plating. Among them, sputtering in which the temperature of the glass beads 11 does not substantially rise is preferable. On the other hand, C
The method in which the temperature at the time of coating exceeds 600 ° C., such as VD,
This is not preferable because the softening of the glass beads 11 occurs. The thickness of the metal titanium thin film is preferably in the range of 47 to 4700 ° in order to obtain the rutile type titanium oxide film 12 having the required retroreflection characteristics and scattering reflection characteristics. If the film thickness is too thick, the rutile-type titanium oxide film 12 is less likely to be formed even when heated for about one hour at a temperature lower than the melting point of the glass beads 11 in the atmosphere. On the other hand, if the metal titanium thin film is too thick, the irregularities on the surface of the thin film become large, and the retroreflection characteristics and the scatter reflection characteristics deteriorate. Conversely, the thickness of the metal titanium thin film is 470
If Å is not reached, the rutile-type titanium oxide film 12 generated by oxidation of the titanium metal thin film does not exhibit a sufficient light refraction effect, and does not exhibit retroreflection characteristics or scattering reflection characteristics. Therefore, when forming a uniform metal titanium thin film by various dry processes, it is important to control the film thickness while stirring the glass beads 11 at the time of coating.

In this regard, when the powder sputtering method developed by the present inventors is used, a metal titanium thin film can be formed at a relatively low temperature, the film thickness can be easily controlled, and the glass beads 1 can be coated at the time of coating.
Since 1 is sufficiently stirred, the surface of the glass beads 11 can be uniformly covered with the metal titanium thin film. In addition, since a phenomenon in which metal atoms excited to the plasma state collide with the surface of the glass beads 11 at high speed is repeated, the glass beads 1
The reaction between titanium oxide and oxides such as SiO ₂ and Al ₂ O ₃ constituting the metal beads 11 is accelerated by collision energy, and a dense metal titanium thin film having excellent adhesion compared to other methods is used as the glass beads 11. Formed on the surface. In the powder sputtering method, for example, a device for sputtering metal on a powder fluidized bed formed by rotating a rotary container containing powder (JP-A-2-153068, etc.) is used.

Since the titanium metal thin film is extremely thin and uniform, having a thickness of 47 to 4700 °, the rutile type titanium oxide film 12 formed by oxidation of the titanium metal thin film also has a thickness of 5 mm.
It is extremely thin and uniform, from 0 to 5000 °. The light-reflective glass beads 10 according to the present invention have such a very thin rutile-type titanium oxide film 12 formed on the surface of the glass beads 11, so that the light-reflecting glass beads 10 exhibit an interference color, but exhibit transparency and transparency. High refractive index. The interference color changes to various color tones from white to green as the rutile type titanium oxide film 12 becomes thicker from 50 ° to 5000 °. In applications where a deep interference color is required, it is preferable to improve the coloring power by increasing the thickness of the rutile type titanium oxide film 12 to 2500 to 5000 °. Light reflecting glass beads 10 covered with rutile type titanium oxide film 12
Has a predetermined color tone due to optical interference, so that there is no restriction on the color of the paint or resin to be added, and the versatility is very high. However, Cr, Mn, Fe, Ni, Co, Cu
Glass beads 11 containing a transition metal such as Ne or a rare earth element such as Ne or Er as an impurity.
Is sometimes colored yellow-brown and the like, so care must be taken in the incorporation of impurities.

The rutile type titanium oxide film 12 formed on the surface of the glass beads 11 has the following advantages which cannot be seen from the conventional light reflecting glass beads. Abrasion resistance : the rutile type titanium oxide film 12 has a Mohs hardness of 6.0 to 6.0 as compared with the Mohs hardness of 5.5 to 6.0 of soda lime glass.
High Mohs hardness of 6.5. Therefore, the road marking film made of the coating material in which the light reflecting glass beads 10 coated with the rutile type titanium oxide film 12 are dispersed has less wear due to contact with the vehicle tires and rubbing, and excellent durability. Is shown. Solid lubricity : The rutile type titanium oxide film 12 has excellent solid lubricity, works to prevent agglomeration of the glass beads 11 in a paint or resin, and improves the dispersibility of the light reflecting glass beads 10. Stain resistance : Since the rutile-type titanium oxide film 12 has a photocatalytic action, in a road marking film or the like using the light reflecting glass beads 10, dirt or oil attached to the surface is decomposed by a photocatalytic reaction, and the road marking film is coated. Etc. are less likely to become dirty. Therefore, excellent retroreflection characteristics and scattered reflection characteristics are maintained even when used for an intersection or a road marking film in a tunnel where traffic is difficult to clean. Night visibility during rainwater : Since the surface of the rutile type titanium oxide film 12 is in a stable state in which Ti atoms are cross-linked with oxygen, it usually exhibits hydrophobicity and repels rainwater. However, under the condition of irradiation with ultraviolet rays, part of the cross-linking oxygen is released to cause oxygen defects. When moisture binds to the generated oxygen vacancy, chemically adsorbed water (surface hydroxyl group) is generated, and that portion becomes hydrophilic. Here, when the water-storing glass beads 11 are used, the hydrophilicity of the light reflecting glass beads 10 is maintained even at night in rainy weather, so that water easily spreads on the surface of the road marking coating film and visibility is improved. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Glass beads 11 include elemental glass, hydrogen-bonded glass, oxide glass, fluoride glass, chloride glass, sulfide glass, carbonate glass, nitrate glass, and the like.
Various glasses such as sulfate glass are used. Above all,
Oxide glasses such as soda-lime glass, Vycor glass, quartz glass, Pyrex glass and borosilicate glass having a low refractive index and a refractive index of about 1.5 are preferred. The glass beads 11 are formed by blowing a high-temperature glass melt in a high-pressure atmosphere, or by pulverizing and adjusting the raw material glass, floating in a combustion gas, heating and melting, and making the glass particles spherical by the surface tension of the melt. It is manufactured by a method of cooling and solidifying in air. The glass beads 11 have a particle size of 20 to 1 conventionally used for a road marking coating film, a traffic sign reflective tape, and the like.
400 μm particles are preferred. When the particle size is less than 20 μm, it is difficult to make the glass beads 11 into a true spherical shape. Conversely, if the particle size exceeds 1400 μm, it cannot be used for a road marking coating film because it promotes vehicle slip. In addition, each light reflecting glass bead 1 has a smaller particle size.
Since the intensity of the reflected light from zero is uniformed, glass beads 11 having a narrow particle size distribution width are preferred for a higher quality road marking coating film or a traffic sign reflecting tape.

As a source of the rutile type titanium oxide film 12 formed on the surface of the glass beads 11, a titanium alloy such as α phase, β phase, α + β2 phase can be used instead of titanium metal. Specifically, 95% by weight Ti-5% by weight Al,
95% by weight Ti-5% by weight Cr, 95% by weight Ti-5% by weight Fe, 95% by weight Ti-5% by weight V, 95% by weight T
i-5% by weight Mn, 92% by weight Ti-4% by weight Al-4
Wt% Mn, 92 wt% Ti-5 wt% Cr-3 wt%
Al, 95.75% by weight Ti-2.7% by weight Cr-1.
There is a titanium alloy such as 3 wt% Fe-0.25 wt% O, and the color tone of the interference color changes from white to green depending on the type of the alloy element. In the present invention, "metal titanium" is used to include these titanium alloys. However, if the glass beads 11 are coated with Al, Zn, Cr, Ni, Ag, or the like instead of titanium metal, the coating becomes gray-white or gray-black due to heating and oxidation, and thus cannot be put to practical use. After coating metal titanium and alloy such as Al, Si, Zr etc.
TiO ₂ —Al ₂ O ₃ system, TiO ₂ —SiO ₂
Although a composite oxide film such as a TiO ₂ -ZrO ₂ film can be formed, the refractive index becomes smaller as compared with the rutile type titanium oxide film 12.

The glass beads 11 coated with the metallic titanium film are heated to a temperature lower than the melting point of the glass beads 11 in the atmosphere. The heating temperature is appropriately determined according to the melting point of the glass beads 11 to be used.
It is preferable to set the temperature in the range of ° C. If the heating temperature does not reach 550 ° C., the rutile type titanium oxide film 12 is hardly formed, and if the heating temperature exceeds 650 ° C., the glass beads 11 begin to soften depending on the type. The heating time may be about one hour. Actually, it is set in the range of 10 minutes to 2 hours according to the thickness of the titanium metal thin film and the heating temperature. Above all, when heated and oxidized at 550 to 650 ° C. and then rapidly cooled, the glass beads 11 become tempered glass. As a result, when used for a road marking film or the like, wear due to vehicle tires or the like is extremely reduced.

The method of forming the rutile type titanium oxide film 12 by oxidizing an extremely thin metal titanium thin film can be applied to the surface of powder particles other than the glass beads 11. Applicable powder materials include 550-650 ° C in air atmosphere.
As long as it has a smooth surface without melting by heating for about 1 hour,
There is no restriction on the material. For example, the rutile type titanium oxide film 12 can be similarly formed on fused silica beads, fused alumina beads, and the like.

After the rutile type titanium oxide film 12 is formed on the surface of the glass beads 11, the light reflecting glass beads 10 are coated with an organic substance such as a fatty acid in order to improve the dispersibility in the paint and the adhesion to the resin. Alternatively, the light reflecting glass beads 10 may be surface-treated with various coupling agents. Usable coupling agents include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, γ-methacrylic Examples include oxypropyltrimethoxysilane, titanium-based coupling agents, zirconia-based coupling agents, and aluminum-based coupling agents.

The light reflecting glass beads 10 can be blended in paint, printing ink, rubber and the like. The coating composition and the printing ink are prepared by mixing an appropriate amount of the light reflecting glass beads 10 with a solvent and a varnish. At this time, if necessary, a coloring pigment, an ultraviolet absorber, a thickener, a static eliminator,
Dispersants, antioxidants, polishing agents, surfactants, synthetic preservatives, lubricants, plasticizers, conductive fillers, reinforcing agents, and the like may be added. Further, when a luminous pigment, a fluorescent pigment, a luminescent pigment, and the like are blended, a road marking coating film and a traffic sign reflective tape with high visibility even in the rainy night can be obtained. The blending amount of the light reflecting glass beads 10 with respect to the paint or resin is preferably in the range of 5 to 40% by volume in order to obtain sufficient reflected light intensity. If the amount of the light reflecting glass beads 10 is less than 5% by volume, the intensity of reflected light is extremely weak. However, conversely, even if the light reflecting glass beads 10 are compounded in a compounding amount exceeding 40% by volume, no increase in the reflected light intensity corresponding to the increase is observed. In order to impart uniform and fine retroreflection characteristics and scattering reflection characteristics to the entire surface of a road marking coating film or a traffic sign reflective tape, 10
It is preferable to mix the light-reflective glass beads 10 in a paint or a resin in an amount of 30 to 30% by volume.

The paint containing the light reflecting glass beads 10 is applied to a predetermined surface by a brush coating method, a spray method, a doctor blade method, a roll coater method, a bar coater method, or the like.
It becomes a coating film. In addition, the same effect as in the case of being incorporated into a paint can be exerted on a caulking agent for construction and vehicles, and an acrylic or rubber-based adhesive used for putty, adhesive tape and the like. The light reflecting glass beads 10 can also be dispersed in a resin film or a resin molded body manufactured by an extrusion molding method, an injection molding method, an inflation molding method, a blow molding method, or the like. Resins used for resin films and resin molded products include acrylic resins, alkyd resins,
One or more of polyester resin, polyurethane resin, polyethylene resin, polypropylene resin, polybutadiene resin, polycarbonate resin, ABS resin, polyvinyl chloride resin, polyvinyl acetate resin and the like are used.
Also in this case, coloring pigments, ultraviolet absorbers, thickeners, static eliminators, dispersants, antioxidants, polishes, surfactants, synthetic preservatives, lubricants, plasticizers, conductive fillers, reinforcement Agents, phosphorescent pigments, fluorescent pigments, luminescent pigments, etc. can be added as required.

[0024]

EXAMPLES Example 1 [Formation of Metallic Titanium Thin Film] Transparent glass beads (Union Co., Ltd.) used for a traffic sign reflective tape using a powder sputtering apparatus introduced in JP-A-2-153068. Manufactured by Unibeads UB-02L, particle size: 20 to 45 μm, refractive index: 1.5), a metal titanium thin film was formed under the following conditions. A rotating drum having an inner diameter of 200 mm and an axial length of 200 mm is filled with 100 g of glass beads, the pressure of the rotating drum is reduced to 3 × 10 ⁻³ Pa, and the atmosphere in the rotating drum is supplied while supplying argon gas at a flow rate of 15 ml / min. Was kept constant. Then, the input power 0.1
Using a metal titanium target as a sputtering source under the conditions of kW and a frequency of 13.56 MHz, the surface of the glass beads was coated with a metal titanium thin film by magnetron sputtering. After continuing the sputtering for 3 minutes, the metal titanium-coated glass beads in the rotating drum were collected. On the surface of the collected glass beads, a metal titanium thin film having a thickness of 47 ° was formed.

[Heating and Oxidation Treatment Step] 100 g of the obtained metal titanium-coated glass beads were transferred to a stainless steel tray, placed in a muffle-type electric furnace kept in the atmosphere, and heated and oxidized at 650 ° C. for 1 hour. did. The heat-oxidized metal titanium-coated glass beads were taken out of the muffle type electric furnace, and after cooling, the structure of the titanium oxide thin film formed on the surface of the glass beads was examined by X-ray diffraction. As a result, it was found that the metal titanium thin film was turned into white rutile-type titanium oxide by the heat oxidation treatment. In addition, from the relationship between the density of titanium metal and the density of rutile type titanium oxide, the thickness of
It is presumed that the metal titanium oxide thin film corresponds to a rutile type titanium oxide film having a thickness of 50 °.

[Preparation of Coated Plate] Rutile-type titanium oxide-coated glass beads were mixed with a resin for coating to prepare a coating having the following composition. Acrydic A-165 100 parts by weight (Dai Nippon Ink Chemical Industry Co., Ltd., solid content 55% by weight
Resin for acrylic paint) 68% by weight of rutile-type titanium oxide-coated glass beads
(Equivalent to 30% by volume) 150 parts by weight of a thinner containing toluene as a main component The prepared paint is applied on an ABS resin substrate by air spray and dried at 80 ° C. for 20 minutes to obtain a film thickness of 10%.
A coated plate on which a coating film of 0 μm was formed was prepared.

[Evaluation of Light Reflection Characteristics] The coating film formed on the ABS resin substrate was irradiated with a flashlight at an incident angle of 45 degrees, and the retroreflection characteristics and the scattering reflection characteristics were examined. As for the retroreflection characteristics, the reflected light intensity was measured near the incident angle of the flashlight of 45 degrees. As for the scattering reflection characteristics, the intensity of specular reflection light at an incident angle of 45 degrees of the flashlight was measured. The results of the investigation were compared with conventional glass beads (comparative example), and visually determined according to the following criteria. Evaluation criteria for retroreflection characteristics A: Extremely strong retroreflection light was observed. ：: Very strong retroreflected light was observed. Δ: Weak retroreflected light was observed. X: Retroreflection light was not observed. Evaluation criteria for scattered reflection characteristics A: Extremely strong scattered reflected light was observed. ：: Remarkably strong scattered reflected light was observed. Δ: Weak scattered reflected light was observed. ×: Scattered reflected light was not observed.

Comparative Example 1: Using the same coating material containing 30% by volume of transparent glass beads as in Example 1, ABS under the same conditions
A coated plate having a 100 μm-thick coating film formed on a resin substrate was prepared. The retroreflection characteristics and the scatter reflection characteristics of the obtained coated plate were examined by the same evaluation method. Comparative Example 2: Transparent high refractive index glass beads (manufactured by Union Corporation: Unibeads UB-02UF, particle size: 20 to 45 μm)
m, a refractive index of 1.9), and 30% by volume.
A coated plate was produced in the same manner as in Example 1. The retroreflection characteristics and the scatter reflection characteristics of the obtained coated plate were examined by the same evaluation method.

Example 2: In the same procedure as in Example 1, transparent glass beads (Unibeads UB-108L, manufactured by Union Co., Ltd., particle size: 10) used in a commercially available road marking paint.
6 to 850 μm, refractive index 1.5)
After forming the metal titanium thin film of Å, 650 in air atmosphere
The titanium metal thin film was oxidized by heating at 1 ° C. × 1 hour to form a yellow rutile type titanium oxide film having a thickness of 2000 °.
On the other hand, 100 parts by weight of a polyvinyl chloride resin, 20 parts by weight of a polyester plasticizer, 4 parts by weight of a heat stabilizer and 1 part by weight of an ultraviolet absorber are 70 parts by weight of tetrahydrofuran-250.
A transparent liquid synthetic resin composition was prepared by dissolving in a mixed solvent of parts by weight of cyclohexanone and kneading with a Hobart mixer. 55 parts by weight of yellow rutile-type titanium oxide-coated glass beads were mixed with the liquid synthetic resin composition to prepare a synthetic resin paint. The synthetic resin paint was applied on a polyester film substrate so as to have a dry film thickness of 2800 μm, solidified by preliminary drying at 60 to 100 ° C., and further dried at 150 ° C. The dried synthetic resin coating film was formed into a film and peeled from the substrate. The resulting synthetic resin film had a thickness of 1000 μm. The light reflecting glass beads according to the present invention were contained in the synthetic resin film at 30% by volume, and the individual beads were oriented almost parallel to the film surface. With respect to this synthetic resin film, retroreflection characteristics and scattering reflection characteristics were examined by the same evaluation method.

Comparative Example 3 A synthetic resin film having a thickness of 1000 μm and containing 30% by volume of the same transparent glass beads as in Example 2 was produced under the same conditions as in Example 2. For the obtained synthetic resin film, the retroreflection characteristics and the scatter reflection characteristics were examined by the same evaluation method. Comparative Example 4: Same high refractive index transparent glass beads 3 as Comparative Example 2.
A 1000 μm-thick synthetic resin film containing 0% by volume was produced under the same conditions as in Example 2. For the obtained synthetic resin film, the retroreflection characteristics and the scatter reflection characteristics were examined by the same evaluation method. Comparative Example 5: Except for using high-refractive-index transparent glass beads on which a rutile-type titanium oxide film having a thickness of 2000 mm was formed,
A synthetic resin film was produced in the same manner as in Comparative Example 4, and the retroreflection characteristics and the scattering reflection characteristics of the obtained synthetic resin film were examined.

Example 3 In the same procedure as in Example 1, transparent glass beads (Unibeads UB-114L, manufactured by Union Co., Ltd., particle size: 42) used in commercially available road marking paints.
5 to 1400 μm, refractive index 1.5)
After a 0 ° metal titanium thin film is formed,
The metal titanium thin film was oxidized by heating at 0 ° C. × 1 hour to form a green rutile type titanium oxide film having a thickness of 5000 °. 45 parts by weight of rutile-type titanium oxide-coated glass beads were added to 100 parts by weight of a transparent polystyrene resin. The mixed resin was melt-mixed at 250 ° C. using a vented 40 mm extruder, and then extruded into pellets. The resulting pellets are injection molded, length 60mm, width 35mm, plate thickness 3m
m test pieces were prepared. The molded test specimen contained 30% by volume of light reflecting glass beads according to the present invention. With respect to the obtained test pieces, the retroreflection characteristics and the scatter reflection characteristics were examined in the same manner as in Example 1.

Comparative Example 6: The same length as in Example 3 including 30% by volume of transparent glass beads, length 60 mm, width 35 mm, thickness 3
mm injection molded test pieces were prepared. With respect to the obtained test pieces, the retroreflection characteristics and the scatter reflection characteristics were similarly examined. Comparative Example 7: Transparent high refractive index glass beads (Unibeads UB-114UF manufactured by Union Co., Ltd., particle size 425 to 1)
Example 3 except that 400 μm and a refractive index of 1.9) were used.
Under the same conditions as above, length 60mm, width 35mm, thickness 3mm
Injection molded test pieces were prepared. With respect to the obtained test pieces, the retroreflection characteristics and the scatter reflection characteristics were similarly examined.

The examination results of Examples 1 to 3 and Comparative Examples 1 to 7 are shown in comparison with Table 1. As is clear from Table 1, no scattered reflected light was observed in any of the comparative examples using the glass beads on which the rutile-type titanium oxide film was not formed. Further, among the glass beads of the comparative example, those using general-purpose glass beads having a low refractive index had weak retroreflection light. Even when glass beads having a high refractive index were used, the intensity of retroreflected light was increased, but retroreflected light of sufficient intensity was not obtained. On the other hand, in the case of using the light reflecting glass beads according to the present invention, extremely strong retroreflected light and scattered reflected light were observed. Therefore,
When the road marking coating film and the traffic sign reflection tape are produced using the light reflecting glass beads, it can be understood that the sign or the sign can be visually recognized from a far distance not only at night in fine weather but also at night in rainy weather.

[0034]

[0035]

As described above, the light-reflecting glass beads of the present invention have a high refractive index, such as a combination lens, because a rutile-type titanium oxide film is provided on the surface of the glass beads having a low refractive index. Obtained and exhibit excellent retroreflection characteristics and scattering reflection characteristics. When a road marking coating film or a traffic sign reflecting tape is produced using a paint or resin containing the light reflecting glass beads, a sign or sign that can be easily viewed from a long distance at night in fine weather or night in rainy weather can be obtained. Utilizing the excellent retroreflective characteristics and scattered reflective characteristics, various road components such as guardrails, median strips, lighting, vehicles closed, tunnel inner walls, highway tollgate outer walls, highway noise barriers, helmets and automobiles It can also be used as a vehicle member such as a car body such as a motorcycle or a bicycle, a license plate, a bumper, etc., and has a markedly improved visibility and a marked effect on traffic safety. Furthermore, the roof,
A wide range of building materials such as exterior walls, interior walls, partitions, gates, garages, fences, stair railings, stair steps, corridor corners, signs and neon sign mounting plates, and a wide range of home appliances, cosmetics, stationery, sundries It can also be used in the field.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the retroreflection characteristics of a road marking coating film produced by using general-purpose glass beads in a clear night (a) and a rainy night (b).

FIG. 2 is a view for explaining the retroreflection characteristics of a road marking coating film produced using high refractive index glass beads in a clear night (a) and a rainy night (b).

FIG. 3 shows a reflective tape for traffic sign (a) in which an aluminum vapor-deposited film is interposed between a coating film in which light-reflective glass beads are dispersed and a base cloth, and a light-reflective glass bead whose half surface is coated with an aluminum vapor-deposited film. Reflective tape for traffic signs with dispersed coating (b)

FIG. 4 is a diagram for explaining the retroreflection characteristics of a road marking film produced by using the light-reflective glass beads according to the present invention at night in fine weather (a) and at night in rainy weather (b).

FIG. 5 is a reflective tape for a traffic sign produced using the light reflective glass beads according to the present invention.

[Explanation of symbols]

3: water film 5: backing 9: transparent resin layer 10: light reflective glass beads 11: Glass beads 12: rutile type titanium oxide film L _in: incident light L _out: retroreflected light L _ref: diffused reflection light

Claims (4)

[Claims] 1. A light reflecting glass bead wherein the surface of a glass bead having a refractive index of 1.6 or less is covered with a transparent or translucent film having a refractive index of 2.6 or more. 2. The glass bead having a refractive index of 1.6 or less is soda lime glass having a particle size of 20 to 1400 μm.
The light reflecting glass beads as described. 3. The light-reflective glass beads according to claim 1, wherein the transparent or translucent film having a refractive index of 2.6 or more is rutile type titanium oxide having a thickness of 50 to 5000 °. 4. A light reflection method in which metallic titanium is coated on the surface of soda-lime glass having a refractive index of 1.6 or less, and then heated to 550 to 650 ° C. in an air atmosphere to oxidize the metallic titanium to rutile-type titanium oxide. Manufacturing method of glass beads.