JPH02228692A - Sheet material for high-luminance all-weather road surface marker - Google Patents

Abstract

PURPOSE:To obtain a high retroreflection efficiency for >=60 deg. angle of incidence by providing a retroreflection sheet having a glass bead layer of glass beads which are partially exposed to the air and have a relatively large diameter, a glass bead layer of glass beads having a relatively small diameter behind the glass bead layer above, and a reflection layer consisting of a metallic vapor-deposited film or the like. CONSTITUTION:This sheet material consists of a retroreflection sheet 1 and a base sheet 2, and it is necessary for a resin 3 of the retroreflection sheet 1 to be transparent and to satisfactorily hold glass beads 4 having a relatively large diameter. Glass beads 4 having a relatively large diameter, especially, 0.25 to 2mm particles size are at least partially exposed to the air. A glass bead layer 5 of glass beads having a relatively small diameter is buried and fixed apart from glass beads 4, and a reflection layer 8 consisting of a metallic vapor-deposited film or the like is provided on the rear face of a resin layer 7. The base sheet 2 is made of the rubber, a synthetic resin, or the like coupled to the rear of the retroreflection sheet 1. Thus, a sufficient reflection luminance is obtained even for the light made incident at a large angle, and a high reflection luminance is obtained even in the rain and at night.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sheet material for road markings, which has high retroreflection brightness especially against light rays incident at a large angle, and has high retroreflection brightness even in rainy weather and at night. The present invention relates to an all-weather road marking sheet material that has reflective brightness.

[Conventional technology]

BACKGROUND ART Retroreflective road marking sheet materials are used as road markings such as road markings and road signs. Various types of road marking sheet materials currently in use are made visible even at night by scattering or mixing glass beads into the resin layer as retroreflective elements.

When the marking surface of these road marking sheet materials is covered with a film of water during rainy weather, most of the upper hemisphere of the glass beads that have a reflective function are exposed to the atmosphere from the sheet material surface and are buried in the water film. As a result, its reflex function is impaired,
A common drawback is that visibility is extremely poor during rainy weather and at night.

Therefore, several proposals have been made to improve the visibility of such road marking sheet materials in rainy weather and at night. For example, U.S. Patent No. 4.388.359
No. 1, etc., attempts to improve visibility in rainy weather and at night by providing a large number of irregularities on the surface of a sheet material in which glass beads are embedded. Also, JP-A-62-2114
Publication No. 03 discloses that glass beads with a refractive index of 2.0 to 2.4, which do not relatively lose their retroreflectivity even in rainy weather or at night, are embedded in the base sheet at intervals in the longitudinal direction of the base sheet. By forming a large number or partially continuously, visibility is improved during rainy weather and at night.

[Problem to be solved by the invention]

These conventional all-weather road marking sheet materials exhibit the expected visibility when the light from the headlights of a vehicle driving at night is irradiated onto the road marking sheet material at a relatively small angle of incidence. However, the light from vehicle headlights is normally 60° to 8° relative to the road marking sheet.
Because it is irradiated at a very large incident angle of 0'', the retroreflection brightness decreases at such a large incident angle, and furthermore, in rainy weather, the retroreflection brightness is not affected by the water film and further decreases. However, a decrease in the reflective brightness of road marking sheet materials during rainy weather and nighttime is extremely dangerous, so it is desirable to improve the retroreflective brightness of road marking sheet materials against light rays that enter at such large incident angles. was.

The present invention has been made in order to solve the above-mentioned problems of conventional road marking sheet materials, and the road marking sheet material is incident at a large angle of 60 degrees or more required during normal use. An object of the present invention is to provide an all-weather road marking sheet material that has sufficient reflective brightness against light rays and has high reflective brightness even in rainy weather and at night.

[Means and effects for solving the problem] In order to achieve the above object, the high brightness all-weather type road marking sheet material according to the present invention is provided with a comparative sheet material which is at least partially exposed in the air and bonded with a transparent resin. a relatively large diameter glass bead layer and a relatively small diameter glass bead layer embedded and fixed at a distance from the relatively large diameter glass beads in a transparent resin layer behind the relatively large diameter glass beads; and a reflective layer made of a metal vapor deposited film provided on the back surface of the resin layer, and a base sheet made of a material such as rubber or synthetic resin bonded behind the retroreflective sheet. It is characterized by

With the above configuration, according to the present invention, light rays incident at a large incident angle of 60° or more are transmitted from relatively large diameter glass beads to relatively small diameter glass beads in the retroreflective sheet via the transparent resin. After being incident and reflected on the reflective layer, the light passes through relatively small diameter glass beads, transparent resin, and relatively large diameter glass beads and is retroreflected. Therefore, the refractive index of relatively large-diameter glass beads, relatively small-diameter glass beads, and resin, the particle size of relatively large-diameter glass beads, relatively small-diameter glass beads, and the relatively large-diameter glass beads are relatively large. 60' by appropriately selecting and combining the resin spacing between small diameter glass beads, etc.
High retroreflection efficiency can be obtained at such a large incident angle.

Furthermore, although the optical mechanism of tT 4H1 is unknown, by adopting the configuration of the present invention described above, even when the exposed portion of a relatively large diameter glass bead is covered with a water film, the retroreflection brightness is reduced in a dry state ( It was found that there is no substantial decrease in retroreflection brightness compared to that under clear weather conditions (corresponding to nighttime conditions), and in fact, there are cases in which retroreflection brightness improves compared to dry conditions.

Next, the structure of the high brightness all-weather type road marking sheet material according to the present invention will be explained with reference to the drawings.

In FIG. 1, the road marking sheet material A of the present invention consists of a retroreflective sheet 1 and a base sheet 2.

The resin 3 of the retroreflective sheet 1 needs to be transparent and have good holding power for relatively large diameter glass beads 4, and also has abrasion resistance, stain resistance, and discoloration resistance because it is used outdoors. It is necessary to take these factors into consideration when making a selection. As resins that do not meet these conditions, crosslinked acrylic polymers, aliphatic urethanes, and polyesters are suitable, and other thermoplastic materials such as vinyl polymers and cellulose acetate butyrate can also be used.

In the present invention, by providing at least a portion of the relatively large diameter glass beads 4 exposed in the air, a large amount of light is received even if the irradiated light beam is at a wide angle, and a large amount of light reaches the lower reflective layer. Therefore, in order to reflect wide-angle light, the larger the particle size of the glass beads 4, the greater the effect, but considering the use on road surfaces, 2.
Beads larger than nun tend to fall off and are problematic in their use.

Moreover, if it is less than 0.2'z+++n, the brightness will decrease and the object of the present invention cannot be fully achieved.Therefore, the particle size of the large-diameter glass beads 4 needs to be selected within the range of 0.25 to 2+m. In particular, those in the order of 0.25 to 0.5 are preferred.

The large diameter glass beads 4 preferably have a refractive index in the range of 1.75 to 2°2. When the refractive index is 1.75, the brightness decreases, while glass beads having a refractive index of more than 2.2 are difficult and expensive to manufacture.

The large-diameter glass beads 4 are uniformly dispersed in a layer covering 30 to 60% of the total surface area.

In the retroreflective sheet 1, relatively small diameter glass beads 5 are embedded and fixed in a transparent resin layer behind relatively large diameter glass beads 4 at a distance from the glass beads 4 to form a layer. A reflective layer 8 made of a metal vapor deposition film or the like is provided on the back side of the transparent resin layer behind the small diameter glass beads 5.

It is preferable to use small-diameter glass beads 5 having a particle diameter of 53 to 63 μm and a refractive index of about 2.0 to 2.2. The reflective layer 8 is located behind the glass beads 5 and is located at the focal point of the glass beads 5. This can be obtained by forming a metal film such as an aluminum film on the back surface of the focusing resin layer 7, which is preferably adjusted so as to match the above, by a known method such as a vacuum deposition method. Regarding the retroreflective sheet, start with the lower layer a shown in the enlarged cross-sectional view in Figure 2! J! ! Further explanation will be given based on an example in which an upper layer is provided on the lower layer a. A focusing resin layer 7 for adjusting the film thickness is provided, and a reflecting layer 8 made of a metal vapor deposited film or the like is formed on the back surface of the focusing resin layer 7 in a curved surface concentric with the glass beads 5. , a surface layer 9 is provided to reinforce the glass bead holding resin layer 6.

Note that 10 is an adhesive layer made of acrylic resin or the like. The glass beads 5 are embedded and fixed at 20 to 30% of the particle size in the glass bead holding resin layer 6. When providing the surface resin layer 9, it is sufficient to have a film thickness of about 10 to 30 μm.A transparent resin layer 3 is provided on the upper layer (a) or the lower layer (a) by coating or the like, and this transparent resin layer 3 is It has a structure that holds large-diameter glass beads 4, and the transparent resin layer 3 here may have a minimum thickness of 20 μm or more for fixing the glass beads 4.
Considering the ability to hold glass beads on an actual road surface, it is necessary to have a thickness of at least 70 μm. The film thickness has a correlation with the particle size of the glass beads 4, and is preferably half or less of the particle size. Therefore, a film thickness of 20 to 100 μm is possible, and a preferable film thickness is 70 to 100 μm.

If the film thickness is less than 20 μm, the holding power of the glass beads 4 will be reduced, and if it exceeds 100 μm, the brightness will be reduced, which are both undesirable.

Note that the retroreflective sheet 1 is not limited to the manufacturing method described above, and can be manufactured using large-diameter glass beads 4111I! Of course, other methods such as sequential production starting from I may be used.

The base sheet 2 bonded to the back of the retroreflective sheet 1 must be made of a material that has excellent adaptability to deforming road surfaces and mechanical durability. Unvulcanized synthetic rubbers such as butylene isoprene rubber (IIR), chloroprene rubber (CR), chlorosulfonated polyethylene, urethane rubber, and synthetic resins such as vinyl chloride are used, and appropriate filling with calcium carbonate powder, etc. is used. agent.

Pigments for coloring and the like are added and formed into a sheet with a thickness of 5 mm or less by roll rolling or the like.

An adhesive layer 11 is formed on the lower surface of the base sheet 2 to a suitable thickness of 50 μm or more, preferably about 100 to 200 μm.
will be established. Although a release paper 12 is usually attached to the lower surface of the adhesive layer 11, the release paper 12 may not be used depending on the type of adhesive used.

To manufacture the base sheet 2, a filler is added to the unvulcanized synthetic rubber or synthetic resin, which is the constituent material of the base sheet mentioned above.
A desired amount of pigment, etc. is added, kneaded, rolled by hot rolling, formed into a sheet with an appropriate thickness of 5 mm or less, rolled up, and, if necessary, further unrolled and coated with release paper with a thickness of 50 μm.
The adhesive coated to an appropriate thickness is further superimposed on the lower surface of the sheet and rolled up.

Further, the base sheet 2 may have a two-layer structure including a base layer having the above composition and a thin colored layer provided on the base layer. In this case, the thickness of the base layer is preferably 1.0 to 1.6 m, and the thickness of the colored layer on the base layer is preferably about 20 to 25 μm.

The thin colored colored layer on the base layer has the same characteristics as those of the base layer described above, and is required to be closely adhered to the base layer and colored in a desired color for road marking. Therefore, it is preferable to use the same type of unvulcanized synthetic rubber or a different type of rubber having the same properties as the unvulcanized synthetic rubber used for the above-mentioned base layer, with an appropriate coloring agent added thereto.

When forming a colored layer on the base layer, unwind the base layer and add a coloring agent to the upper surface of the unvulcanized synthetic rubber material to give the desired hue by dissolving it in a solvent. A colored layer is formed by applying the prepared fluid in an amount that gives a desired thickness to the dried coating film.

The base sheet 2 can also have a two-layer structure: a relatively hard upper layer with excellent mechanical durability and a relatively soft lower layer with excellent deformation adaptability to the road surface. In this case, the lower layer has a hardness of 30° to 75° according to JIS K6301.
If it is made of a material that has a strong restoring force of 50% or less, it has extremely good deformation adaptability to the road surface and is less likely to peel off after being attached to the road surface.

When the base sheet 2 has such a two-layer structure, the hardness and recovery rate described above can be obtained, as one method, by adding a relatively large amount of plastic material to the formulation of the lower layer. The amount of plastic material added in the entire formulation needs to be 2 parts or more.

Examples of plastic substances include elastomers and plasticizers (D.

0, P, chlorinated paraffin, epoxy, etc.), liquid rubber, etc. are suitable. The main ingredients for both the upper and lower layers are acrylonitrile butadiene rubber (NBR), inbutylene isoprene rubber (IIR), and talolobrene rubber (
Unvulcanized synthetic rubber such as CR, ), synthetic resin such as chloro-17 sulfonated polyethylene, chlorinated polyethylene, vinyl chloride, and other known materials for road marking sheet materials can be used, and if necessary, A suitable filler such as calcium carbonate powder, pigment for coloring, etc. are added, and a sheet having a thickness of 2 cm or less is formed by rolling or the like. The lower surface of the lower layer has a film thickness of 50 μm or more, preferably 100 μm or more.
An adhesive layer is provided to a suitable thickness of about 200 μm. The adhesive layer can be formed by applying adhesive to a desired thickness on release paper and overlapping it on the lower surface of the lower layer.

To manufacture this two-layer base sheet, desired amounts of fillers, pigments, etc. are added to the unvulcanized synthetic rubber or synthetic resin that constitutes the upper and lower layers, and a plastic material is added to the lower layer. The desired amount is added and kneaded, and then rolled by hot rolling to form upper and lower layers of appropriate thickness of 2 mm or less, respectively, and a release paper with a thickness of 50 μm
The adhesive coated to an appropriate thickness is layered on the lower surface of the lower layer.

After preparing the upper layer and the lower layer in this way, an adhesive is applied to the upper surface of the lower layer, or the vicinity of the upper surface of the lower layer 11 is softened by heating, and the upper layer is superimposed and bonded together. Alternatively, the existing upper layer is superimposed on the lower layer extruded in an extrusion molding process, and the layers are pressed and bonded together using a pressure roll.

Also, instead of manufacturing the upper and lower layers as separate sheets and then stacking and joining these two sheets together, a single pace sheet is formed by the composition of the lower layer, and the upper half is cured by electron beam irradiation. The upper layer and the lower layer may be formed as an integral base sheet from the beginning by, for example, forming the upper layer as the upper layer and using the lower half portion that is not irradiated with the electron beam as the lower layer.

The road marking sheet material of the present invention can be obtained, for example, by laminating the retroreflective sheet 1 formed as described above and the base sheet 2 separately formed by the above method by thermocompression bonding.

〔Example〕

Next, one embodiment of the present invention will be described.

(1) Formation of the lower layer a of the retroreflective sheet 1 A resin made by mixing 100 parts of a modified acrylic resin as a resin for forming the surface resin layer 9 on a carrier film (polyester film) and 10 parts of a melamine resin or isocyanate as a crosslinking agent. was applied to a film thickness of 10 to 30 μm, and dried and cured to form a surface resin layer 9.

Next, 100 parts of a modified acrylic resin and 15 parts of a crosslinking agent are used as resins to form a glass bead holding resin layer 6 on the surface resin layer 9.
A resin prepared by mixing the above parts is applied to a film thickness of 10 to 40 μm, and in a semi-dry state, the particle size is 53 to 63 μm and the refractive index is 2.
．． The glass beads 5 of No. 2 were uniformly scattered, and the resin was dried and hardened to fix the glass beads 5, thereby forming a glass bead holding resin layer 6.

Next, the glass beads 51I of the glass bead holding resin layer 6 are
In III, a resin formed by mixing 100 parts of a modified acrylic resin and 5 to 10 parts of a crosslinking agent as a resin for forming the focal resin adjustment layer 7 is dissolved in a mixed solution of MIBK and toluene, and the resin is in a state after the solvent is evaporated. The focus adjusting resin layer 7 is coated so that it becomes about 30 t/trr, dried and hardened.
was formed.

A reflective layer 8 was formed by depositing an aluminum reflective film on the exposed surface of the focus adjustment resin layer 7 thus formed using a vacuum deposition method.Next, an acrylic adhesive was applied to a release paper and laminated on the aluminum deposited surface. The lower layer a of the retroreflective sheet 1 was completed by removing the carrier film of the rear top layer 9. The refractive index of the resin in the lower layer a of this retroreflective sheet 1 was 1.52.

(2) Formation of the upper layer of the retroreflective sheet 1 A resin formed by mixing 100 parts of a modified acrylic resin and 15 parts of a crosslinking agent is coated on the surface of the lower layer a of the retroreflective sheet 1 to form the upper layer. Coating to a thickness of 75 μm, semi-dry particle size of 350 to 500 μm, refractive index of 1.90 to 1.9
The upper layer was formed by uniformly scattering the glass beads 4 of No. 2 to cover 32% of the entire surface and drying and curing the resin. The refractive index of the resin in the upper layer was 1.52.

(3) Formation of base sheet 2 The base sheet 2 was formed of two layers: a relatively hard upper layer with excellent mechanical durability and a relatively soft lower layer with excellent deformation adaptability to the road surface.

To form the upper layer, 30 parts of NBR, 5 parts of BR, 15 parts of petroleum resin, 230 parts of TIO, Ca C031
40 parts were kneaded and formed into a sheet 1~ with a thickness of 0.711 m and a width of 1,000 ru+ by extrusion rolling at a processing temperature of 90°C. In addition, to form the lower layer, 30 parts of NBR, BR
5 parts, petroleum resin 15 parts, TiO□30 parts, Ca C03
140 parts, liquid rubber 5 parts, chlorinated polyethylene 7 parts, D
.

A pressure-sensitive adhesive was applied to the lower surface of the lower layer to a thickness of 100 μm, and a release paper 12 was overlaid to form an adhesive layer 11. Next, a pressure-sensitive adhesive was applied to the upper surface of the lower layer, the upper layer was overlapped, and both were adhered, and a release paper coated with a pressure-sensitive adhesive was also overlaid on the upper surface of the upper layer to complete the base sheet 2.

(4) Completion of sheet material for road markings Remove the release paper laminated on the back side of the retroreflective sheet 1 and the release paper laminated on the upper surface of the upper layer of the base sheet 2, and attach the retroreflective sheet 1 and base sheet 2 to each other. The adhesive was heat-pressed and laminated to complete the high brightness all-weather road marking sheet material of the present invention.

(5) Measurement of retroreflection brightness The retroreflection brightness of the road marking sheet material of the above example was measured by varying the angle of incidence of the light beam between 60" and 80°. Measurements were made for each.For comparison, the above-mentioned U.S. patent cylinder 4,
Road marking sheet material of the type described in No. 388,359 (
(hereinafter referred to as "conventional product A") and the above-mentioned JP-A-62-21
Regarding the road marking sheet material of the type described in Publication No. 1403 (hereinafter referred to as "conventional product B"), the retroreflection brightness was measured under the same conditions as in the above example.

The brightness was measured using the brightness measurement method according to JIS Z9117. For the brightness when the glass beads were wet with water, the brightness was measured with the product completely wet by pouring water into the acrylic plate, and then the decrease in brightness due to the acrylic plate was measured. Don't adjust it. The measurement results of the retroreflection brightness of each of these road marking sheet materials are shown in Table 1 below and FIG. 3.

From the above measurement results, the road marking sheet material of the present invention is 6
It can be seen that it has higher retroreflection brightness than conventional products at large incident angles of 0° to 80°. In addition, in all conventional products, the brightness is lower when the glass beads are wet than when they are dry, but in the case of the road marking sheet material of the present invention, the brightness is lower when the glass beads are wet. Rather, the result was that the brightness was high.

Furthermore, in order to investigate the influence of the film thickness of the focus adjusting resin layer 7 in the retroreflective sheet 1 on the retroreflection brightness in the above-mentioned embodiment of the present invention, when the amount of resin applied in the focus adjusting resin layer 7 was varied. Retroreflection brightness was measured using the same measurement method as above. Sample A with coating amount of 23.49g/-
, 29°77 t/gtf as sample B, 3
5.38 g/d was measured as sample C1, and the results are shown in Table 2 below and FIG.

From the above measurement results, it can be seen that in the road marking sheet material of the present invention, the thickness of the focusing resin adjustment layer 7 in the retroreflective sheet 1 is such that sample B provides the highest retroreflection brightness. In addition, in all of Samples A, B, and C, the results showed that the retroreflection brightness was higher when the glass beads were wet with water than when the glass beads were dry.

〔Effect of the invention〕

As described above, according to the present invention, light rays incident at a large incident angle of 60' or more are incident on the small diameter beads from the large diameter beads of the retroreflective sheet through the transparent resin, and are reflected at the reflective layer. After that, it passes through small diameter beads, transparent resin and large diameter beads and is retro-reflected. Therefore, the refractive index of large-diameter beads, small-diameter beads, and resin, the particle size of large-diameter beads and small-diameter beads, and the spacing of resin between large-diameter beads and small-diameter beads, etc. are appropriately selected and combined. As a result, it is possible to obtain higher retroreflection efficiency than the conventional one at a large incident angle of 60' or more.

Furthermore, by adopting the above-mentioned configuration of the present invention, even if the exposed portion of the large-diameter bead is covered with a water film, the retroreflection brightness does not substantially decrease compared to the dry state, and in the example, it is possible to Since the retroreflection brightness is improved compared to the dry state, the retroreflection brightness in rainy weather can be increased by appropriately selecting and combining the particle size of each glass bead, the interval between each glass bead, etc.

In addition, since the large-diameter glass beads are exposed in the air, the irradiated light beam is wide-angle and receives a large amount of light.
A large amount of light can be taken in to the lower reflective layer.

Further, since a base sheet mainly made of unvulcanized rubber or the like is provided on the back of the retroreflective sheet layer, when a vehicle passes by, the surface glass beads are less likely to fall off because the base sheet cushions the impact of the vehicle.

In addition, the thickness of the resin in the upper layer of the retroreflective sheet was increased by 20 to 1
By setting the thickness in the range of 00 μm, it is possible to eliminate the disadvantages that the glass beads tend to fall off when the diameter is less than 2 μm, and the reflected brightness decreases when the diameter exceeds 100 μm.

In addition, by setting the particle size of the large-diameter glass beads in the upper layer of the retroreflective sheet to a range of 0.25 to 2 nm, Oo
It is possible to eliminate the drawbacks that the brightness is low when it is less than -25r, and it is easy to fall off when it exceeds 2 r.

Furthermore, the refractive index of the large-diameter glass beads is 1.75.
By setting the value to 2.2, it is possible to eliminate a decrease in brightness below 1.75 and a price increase when it exceeds 2.2.

[Brief explanation of the drawing]

In the accompanying drawings, FIG. 1 is a cross-sectional view of a high-intensity all-weather road marking sheet material of the present invention, FIG. 2 is an enlarged cross-sectional view of the lower layer of a retroreflective sheet, and FIG. A graph showing the retroreflection brightness in comparison with a conventional product. FIG. 4 is a graph showing the relationship between the film thickness of the focusing resin adjustment layer and the retroreflection brightness in an example of the present invention. 1... Retroreflective sheet, 2... Base sheet, 3...
...Resin, 4...Large diameter glass beads, 5...Small diameter glass beads

Claims (3)

[Claims] (1) A layer of relatively large diameter glass beads that are at least partially exposed to the air and bonded with a transparent resin, and a transparent resin layer behind the relatively large diameter glass beads that has a relatively large diameter. a retroreflective sheet having a layer of relatively small diameter glass beads embedded and fixed at a distance from the glass beads of the sheet, and a reflective layer made of a metal vapor deposited film or the like provided on the back surface of the resin layer;
A high brightness all-weather road marking sheet material comprising a base sheet made of a material such as rubber or synthetic resin bonded behind the retroreflective sheet. (2) The particle size of the relatively large glass beads is 0.25~
The high brightness all-weather road marking sheet material according to claim 1, which has a thickness of 2 mm. (3) The refractive index of the relatively large diameter glass beads is 1.75.
The high-intensity all-weather road marking sheet material according to claim 1, which has a luminance of 2.2 to 2.2.