KR102221481B1 - Retroreflective sheet - Google Patents

Abstract

The present invention relates to a retroreflective sheet
The retroreflective sheet according to the present invention for achieving the above objects includes a protective film, an adhesive layer having flame retardancy formed on the protective film, a colored layer formed on the adhesive layer, and a thin film of a low refractive index material on the colored layer. And a thin film of a high refractive index material are formed by repeatedly stacking N (N is a natural number of 2 or more) times in a pair, and incident at the interface between the thin film of the low refractive index material and the thin film of the high refractive index material and the colored layer. And a transparent reflective layer that reflects light, and a light collecting layer formed on the transparent reflective layer. Therefore, since the transparent reflective layer is transparent, the color of the colored layer can be seen from the outside when the surroundings are bright, such as during the daytime, and the transparent reflective layer and colored layer formed by repeatedly stacking thin films of each of a low-refractive-index material and a high-refractive-index material in which light is repeatedly stacked. Since it is reflected at the interface of and at the interface of each thin film of a refractive index material and a high refractive index material, the amount of reflected light increases and ^{can be reflected with a high luminance of about 500 ~ 700 cd/lux*m 2} , and a thin film of a low refractive material and a high refractive material in the transparent reflective layer It is possible to reflect light of the same or similar color as the color of the colored layer by adjusting the thickness of the thin film.

Description

Retroreflective sheet}

The present invention relates to a retroreflective sheet, and in particular, to a retroreflective having a transparent reflective layer to reflect colored light.

A retroreflective sheet is a reflector including a light collecting layer and a reflective layer that reflects incident light in an incident direction as it is. The retroreflective sheet is usually formed in a sheet form, and is processed into a desired shape or pattern on the body surface of the adherend, and is attached to a selected part of a uniform such as road sign or firefighters by thermal compression or sewing, thereby providing visibility. (visibility) is improved so that the surrounding environment is easily displayed even in dark places. Therefore, if the retroreflective sheet is attached to the clothing worn by people working on roads or dangerous places, such as environmental cleaners, firefighters, police, factory workers, construction site workers, and safety personnel at each part, the wearer's position is given to the surrounding people. Can be surely confirmed, it can have a great effect on the protection and safety of the wearer.

1 is a cross-sectional view of a retroreflective sheet according to the prior art.

The retroreflective sheet according to the prior art is formed by sequentially stacking a protective film 11, a base layer 13, an adhesive layer 15, a reflective layer 17, a primer layer 19, and a light collecting layer 21.

In the above, the protective film 11 is made of a polyolefin-based film or the like to prevent contamination of the base layer 13.

The base layer 13 is used when the manufactured retroreflective sheet is attached to a product such as clothes or sports shoes by thermo-compression bonding with the protective film 11 removed from the surface thereof, and is formed of a sheet made of a thermoplastic resin. In addition, the base layer 13 may be formed of a flame-retardant cotton fiber to be sewn or adhered with an adhesive after contacting the lower surface of the skin adherend.

The adhesive layer 15 is formed by coating a synthetic resin on the base layer 13. In the above, the adhesive layer 15 may be formed to have flame retardancy by adding a flame retardant before coating the synthetic resin.

The reflective layer 17 is formed by depositing a metal having good light reflection properties such as aluminum on the adhesive layer 15 and reflects incident light.

The primer layer 19 is used to smoothly adhere the metal during the deposition process to form the reflective layer 17 on the surface of a plurality of beads 23 forming the light collecting layer 21. In order to prevent loss of light incident on the reflective layer 17 and light reflected from the reflective layer 17 to the condensing layer 21, it must be transparent.

The light condensing layer 21 is formed on the primer layer 19 and consists of a plurality of beads 23 to focus incident light on the reflective layer 17 and transmits the light reflected from the reflective layer 15 to the outside. . In the above, the light condensing layer 21 reflects the incident light back to the light source, thereby minimizing loss of the amount of reflected light.

However, the retroreflective sheet according to the prior art described above has a problem in that the reflective layer is opaque and does not have various colors. In addition, since the reflective layer reflects only white light when white light is incident, there is a problem that it cannot be used in a portion requiring light having a different color.

Accordingly, an object of the present invention is to provide a retroreflective sheet capable of viewing various colors under a reflective layer from the outside.

Another object of the present invention is to provide a retroreflective sheet that can reflect light of various colors even when white light is incident, and thus can be selectively used in a portion requiring light having a different color.

The retroreflective sheet according to the present invention for achieving the above objects includes a protective film, an adhesive layer having flame retardancy formed on the protective film, a colored layer formed on the adhesive layer, and a thin film of a low refractive index material on the colored layer. And a thin film of a high refractive index material are formed by repeatedly stacking N (N is a natural number of 2 or more) times in a pair, and incident at the interface between the thin film of the low refractive index material and the thin film of the high refractive index material and the colored layer. And a transparent reflective layer that reflects light, and a light collecting layer formed on the transparent reflective layer.

In the above, the colored layer includes either a fluorescent material or a phosphorescent material selectively, or a fluorescent material and a phosphorescent material are included together.

In the transparent reflective layer, two thin films of a material having a low refractive index and a material having a high refractive index each selected from SiO2, TiO2, ZnS, ZnO, Al2O3, ZrO2, Ta2O5, Nb2O5, CaF2, and Na3AlF6 form a pair of N Is formed by repeating 2 or more natural numbers) times.

Accordingly, in the present invention, since the transparent reflective layer is transparent, the color of the colored layer can be seen from the outside when the surroundings are bright, such as during daytime. In addition, since light is reflected at the interface between the transparent reflective layer and the colored layer formed by repeatedly stacking thin films of low and high refractive index materials, and at the interface of each thin film of the refractive index material and high refractive index material, the amount of reflected light is increased, resulting in an increase of 500 ~ 700 cd/ It can reflect with high luminance of about lux*m ^2. In addition, there is an advantage of being able to reflect light of the same or similar color as the color of the colored layer by controlling the thickness of the thin film of the low-refractive material and the thin film of the high-refractive material of the transparent reflective layer.

1 is a cross-sectional view of a retroreflective sheet according to the prior art.
2 is a cross-sectional view of a retroreflective sheet according to the present invention.
3 is a color graph simulating and showing a color change of reflected light according to the thickness of the transparent reflective layer 39.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a retroreflective sheet according to the present invention.

The retroreflective sheet according to the present invention is formed of a protective film 31, a base layer 33, an adhesive layer 35, a colored layer 37, a transparent reflective layer 39, a primer layer 41, and a light collecting layer 43 do.

In the above, the protective film 31 is made of a polyolefin-based film or the like to prevent the base layer 33 from being contaminated.

The base layer 33 is used when the manufactured retroreflective sheet is attached to a product such as clothes or sports shoes by thermal compression with the protective film 31 removed from the surface. It is a sheet formed of a thermoplastic resin such as water (Ethylene Vinyl Acetate Copolymer), TPE (Thermo Plastic Elastomer) or TPU (Thermoplastic Poly Urethane), and is formed to a thickness of about 20 to 500㎛.

In addition, the base layer 33 may be attached to a product such as clothes or sports shoes by sewing a retroreflective sheet made of fabric or non-woven fabric.

The adhesive layer 35 is composed of a liquid synthetic resin such as polyurethane resin, polyester resin, or acrylic resin on the base layer 33, and the adhesive is comma coating, gravure coating, micro gravure coating or slot die head coating. coating) to form a thickness of about 20 µm to 300 µm. In the above, the adhesive layer 35 may be formed to have flame retardant properties by including a flame retardant such as aluminum hydroxide, phosphorus flame retardant, Sb2O3, Br flame retardant or melamine flame retardant.

The colored layer 37 is composed of an adhesive synthetic resin such as a polyurethane resin, an ethylene vinyl acetate copolymer, a polyester resin, a methacrylic resin, or an acrylic copolymer on the adhesive layer 35. It is formed by coating, gravure coating, micro gravure coating, or slot die head coating.

In the above, the colored layer 37 includes dyes or pigments having colors such as R (red), Y (yellow), or B (blue), and is formed to a thickness of about 10 to 100 μm. In addition, the colored layer 37 may optionally include any one of a fluorescent material including a fluorescent dye and a fluorescent pigment, or any one of a photoluminescent material including a photoluminescent dye and a photoluminescent pigment. In addition, the colored layer 37 may include a fluorescent material and a phosphorescent material together.

In the above, the colored layer 37 emits light at night by a fluorescence action, or absorbs and luminesces light in the daytime or indoors, and emits light at night with a light quantity of about 30 cd/lux*m2 or less. Accordingly, the amount of light according to the color of the colored layer 37 is increased by the colored layer 37 at night or in a dark place, thereby improving visibility. In addition, when the colored layer 37 includes a fluorescent material and a photoluminescent material together, fluorescence and photoluminescence may be simultaneously performed.

The transparent reflective layer 39 is a plurality of thin films with two or more layers selected from materials such as SiO2, TiO2, ZnS, ZnO, Al2O3, ZrO2, Ta2O5, Nb2O5, CaF2 and Na3AlF6 on the colored layer 37, for example, low Two thin films of SiO2, a refractive-index material and TiO2, a high-refractive-index material, form a pair and are repeatedly stacked N times (N is a natural number of 2 or more). The transparent reflective layer 39 is vacuum evaporation, chemical vapor deposition (CVD), sputtering, plasma enhanced chemical vapor deposition (PECVD), or ion-beam. It is formed by vapor deposition to a thickness of about 300 to 1000 nm by a vapor deposition method such as.

In the above, the refractive indices of SiO2 and TiO2 forming the transparent reflective layer 39 are different from each other by about 1.4 and 2.4, respectively. Therefore, the SiO2 thin film that is repeatedly laminated N times (N is a natural number of 2 or more) constituting the transparent reflective layer 39 as well as the interface between the transparent reflective layer 39 and the colored layer 37, as well as the light incident through the condensing layer 43. And TiO2 are also reflected at the interface of the two thin films. Therefore, as the number of repeated stacking of the SiO2 thin film and the TiO2 thin film constituting the transparent reflective layer 39, that is, N (N is a natural number of 2 or more) increases, the amount of reflected light increases. Accordingly, the transparent reflective layer 39 may reflect incident light with high luminance of about ^{500 to 700 cd/lux*m 2.}

In addition, in the transparent reflective layer 39, the wavelength of reflected light is repeatedly changed according to the thickness of SiO2 and TiO2. That is, as the thickness of the transparent reflective layer 39 changes, light of various colors is repeatedly reflected. Therefore, the transparent reflective layer 39 can reflect light of the same or similar color as the color of the colored layer 37 by adjusting the thickness of the SiO2 thin film and the TiO2 thin film.

3 is a color graph simulating and showing a color change of reflected light according to the thickness of the transparent reflective layer 39. In the above simulation, the reflectance of the reflected light according to the thickness of the transparent reflective layer 39 was measured as a coordinate value using the McCloud program, and this coordinate value was expressed as a color in the CIE 1931 color space by a standard observer. [Table 1] shows the coordinate values of the reflection color of each reflected light from 10 nm to 500 nm in thickness of the transparent reflective layer 39.

Thickness (nm) Reflectance x Reflectance y Thickness (nm) Reflectance x Reflectance y 10 0.420618447 0.395721865 260 0.3227524 0.421783241 20 0.40734381 0.391600401 270 0.3243355 0.490285493 30 0.410279967 0.394884819 280 0.358598086 0.510773761 40 0.418694604 0.399860047 290 0.398587177 0.492275284 50 0.429618815 0.405432518 300 0.431216641 0.457372845 60 0.443587027 0.412261976 310 0.455541655 0.420194116 70 0.462811529 0.421175063 320 0.473899492 0.386900044 80 0.489228043 0.430444556 330 0.487692367 0.360522243 90 0.518771163 0.429970937 340 0.496126305 0.343954092 100 0.532006446 0.400192078 350 0.495718689 0.34092541 110 0.492819878 0.334661247 360 0.480862033 0.355263257 120 0.386322066 0.280263234 370 0.448019475 0.387262666 130 0.293833983 0.301013243 380 0.404007861 0.427366509 140 0.287069488 0.361884754 390 0.367837816 0.457259165 150 0.328427379 0.410132424 400 0.35533996 0.465452959 160 0.378633322 0.440531598 410 0.366421274 0.455728804 170 0.425397349 0.458580881 420 0.391756006 0.437734271 180 0.464804832 0.463407135 430 0.422391263 0.41832254 190 0.493285813 0.450681501 440 0.452117015 0.400679645 200 0.508788004 0.420217209 450 0.476518412 0.386241465 210 0.511537821 0.378190412 460 0.492127455 0.376117071 220 0.500950267 0.334422963 470 0.49619645 0.371421058 230 0.473274112 0.301854658 480 0.487182492 0.373011817 240 0.425126885 0.29849769 490 0.466074752 0.381112018 250 0.36509375 0.341574646 500 0.437585855 0.394792793

The color graph of FIG. 3 shows the color of the light reflected from the transparent reflective layer 39 with the color coordinate value of [Table 1] as a simulation result of 10 nm per cell. In the above, the color graph of FIG. 3 is generally repeated every about 120 to 170 nm in thickness of the transparent reflective layer 39. Therefore, the transparent reflective layer 39 may reflect light of the same or similar color as the color of the colored layer 37 by adjusting the thickness.

The primer layer 41 is formed on the transparent reflective layer 39. In the above, the primer layer 41 smoothly adheres the metal oxide during the deposition process to form the transparent reflective layer 39. In the above, the light collecting layer 43 must be transparent to prevent loss of light incident on the transparent reflective layer 39 through the bead 45 and the light reflected by the transparent reflective layer 39. Therefore, the primer layer 41 may be formed by coating a polyester-based resin, an acrylic resin, a vinyl-based resin, or a polyurethane-based resin.

The light collecting layer 43 is formed by scattering a plurality of beads 45 to form a layer on the primer layer 41. In the above, the condensing layer 43 is formed of glass having a size of about 20 to 200 μm, a transparent non-glass ceramic, or a transparent synthetic resin, which focuses light incident on a plurality of beads 45.

In the retroreflective sheet according to the present invention having the above-described configuration, light incident through the light collecting layer 43 is retroreflected by the transparent reflective layer 39. In the above, the transparent reflective layer 39 is one pair of a plurality of thin films of two or more layers of a low refractive index material and a high refractive index material selected from materials such as SiO2, TiO2, ZnS, ZnO, Al2O3, ZrO2, Ta2O5, Nb2O5, CaF2 and Na3AlF6. It is formed by repeatedly stacking N (N is a natural number of 2 or more) times. For example, in the transparent reflection layer 39, two thin films of SiO2, a low-refractive-index material having a refractive index of about 1.4, and TiO2, a high-refractive-index material having a refractive index of about 2.4, form a pair of N (N is a natural number of 2 or more). It is formed by repeatedly stacking.

In the above case, the color of the colored layer 37 can be seen from the outside when the periphery is bright due to the transparent reflective layer 39. In addition, since the transparent reflective layer 39 is formed by repeatedly stacking thin films of a low refractive index material and a high refractive index material, light is not only the interface between the transparent reflective layer 39 and the colored layer 37, but also the repeatedly stacked low refractive index material and high refractive index. Since the material is reflected at the interface of each thin film, the amount of reflected light is increased. Accordingly, the transparent reflective layer 39 may reflect incident light with high luminance of about ^{500 to 700 cd/lux*m 2.}

In addition, in the transparent reflective layer 39, the wavelength of reflected light is repeatedly changed according to the thickness of SiO2 and TiO2. That is, as the thickness of the transparent reflective layer 39 changes, light of various colors is repeatedly reflected. Therefore, the transparent reflective layer 39 can reflect light of the same or similar color as the color of the colored layer 37 by adjusting the thickness of the SiO2 thin film and the TiO2 thin film.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those of ordinary skill.

31: protective film 33: base film
35: adhesive layer 37: colored layer
39: light transmitting and reflecting layer 41: primer layer
43: light collecting layer

Claims (3)

Protective film,
A base layer formed on the protective film,
An adhesive layer having flame retardancy formed on the base layer,
A colored layer that is formed on the adhesive layer to have a color and emits light in the same color as the color by fluorescence or photoluminescence when the surrounding is dark, such as at night,
On the colored layer, a thin film of a low-refractive-index material and a thin-film of a high-refractive-index material are formed by repeatedly stacking N (N is a natural number of 2 or more) times in a pair to form an interface between the thin film of the low-refractive-index material and the thin film of a high-refractive-index material It reflects the light incident at the interface between the colored layer and the colored layer, but reflects the color of the colored layer so that the color of the colored layer can be seen from the outside when the surroundings are bright, such as during the day, and together with the light emitted from the colored layer when the surroundings are dark, such as at night. A reflective transparent reflective layer,
Retroreflective sheet comprising a light collecting layer formed on the transparent reflective layer.
The retroreflective sheet according to claim 1, wherein the colored layer selectively includes any one of a fluorescent material and a photoluminescent material, or includes a fluorescent material and a photoluminescent material together.
The method according to claim 1, wherein the transparent reflective layer comprises a pair of two thin films of a material having a low refractive index and a material having a high refractive index, respectively, selected from SiO2, TiO2, ZnS, ZnO, Al2O3, ZrO2, Ta2O5, Nb2O5, CaF2 and Na3AlF6. A retroreflective sheet formed by repeating N (N is a natural number of 2 or more) times.

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