JP3881686B2 - Variable hue retroreflective sheet - Google Patents

Description

  The present invention relates to a hue variable retroreflective sheet used for a car license plate, a security sheet, an advertisement signboard, a vehicle wrapping sheet, a toy, a cosmetic container, a mobile phone and the like.

  The retroreflective sheet is widely used for various applications such as traffic signs, guide signs, warning signs, regulatory signs, car license plates, and advertising signs. As an example of the retroreflective sheet, there is a so-called encapsulated lens type, which includes at least one surface layer, a high refractive index glass bead, a focal layer (also referred to as a focal resin layer), and a metal reflective layer. They are stacked in this order. Further, as another configuration, there is what is called a capsule lens type, a plurality of transparent spheres provided with reflecting mirrors in a lower hemisphere, a support resin sheet holding the plurality of transparent spheres, and the support It is made of a transparent cover film that covers the plurality of transparent spheres by being arranged on the surface of the resin sheet, and a joining portion for holding the cover film is formed on the support resin sheet. In the case of the capsule lens type, since the reflecting mirror is formed directly on the surface of the transparent sphere, the reflection luminance from a small observation angle to a large incident angle is remarkably superior to that of the encapsulated lens type. Also called a high brightness reflective sheet. The retroreflective sheet is further laminated with an adhesive, release paper or release film. Such a retroreflective sheet is attached to a substrate, for example, a metal substrate such as aluminum, iron plate, painted iron plate, stainless steel plate, or a plastic plate such as fiber reinforced plastic (FRP) or hard vinyl chloride. Etc. are used. Such a retroreflective sheet is visually recognized in the same way as normal signs and signboards in the daytime, and reflects light correctly in the direction of the light source projected at night, so the above-mentioned signs, car license plates, signboards, etc. It was useful to remarkably improve the visibility. However, the conventional retroreflective sheet has a hue that is almost similar to the hue of the daylight color and the light that is retroreflected in the direction of the light source when light is projected at night. The hue in the daylight color described above and the retroreflected light when the light is projected at night are defined to be substantially similar.

  For this reason, even if the retroreflective sheeting is used for decoration, signage, etc., the monotonous color that does not change the hue of day and night cannot be dealt with in the diversification of design and individualization in recent various products. There were some disadvantages.

  As a retroreflective sheet that eliminates such lack of design and takes into account decorativeness, there is one proposed in Patent Document 1 below. This is a layer in which a transparent surface film and a glass ball fixing layer are integrated with each other, a glass sphere, a thin focal layer, a metal reflective film, an adhesive layer, and a release paper in order from the surface. The back surface of the layer in which the surface film and the glass ball fixing layer are integrated holds the glass ball in a state where almost half of the glass ball is embedded. The lower half of the glass sphere is covered with a thin focal layer, and a metal reflective film is deposited on the back side of the glass sphere. reflect. In this sheet, when a light ray enters and exits the glass sphere, a light dispersion phenomenon occurs, and rainbow-colored reflected light is obtained. In order to obtain such rainbow-colored reflected light, there is a drawback that the original reflection performance is not provided, but it can be said that the sheet is highly decorative. Such a sheet is called a rainbow film by those skilled in the art.

In addition, a coating film structure and a retroreflective material have been proposed in which retroreflective material and optical interference material are used and retroreflective properties and decorative properties are added. In the following Patent Document 2, a colored reflective layer formed on a predetermined substrate, a retroreflective material disposed on the surface layer side of the colored reflective layer, and a clear layer provided on the surface layer side of the retroreflective material Among them, a coating film structure is proposed in which a glittering material having transparency and regular reflection is dispersedly arranged. Further, the following Patent Document 3, there in the coating structure and a clear layer having a light reflecting layer formed on a predetermined substrate, the retroreflective material that is disposed on the upper side of the light reflective layer In the clear layer, there has been proposed a coating film structure in which an optical interference material having a light transmission property and a regular reflection property is disposed on the upper layer side of the retroreflective material. Further, the following Patent Document 4, a reflective substrate, and a - aligned transparent microspheres on the substrate, the said reflective substrate interference material layer is provided to rise to interference color colored incident light There has been proposed a colored light retroreflective material that retroreflects colored light having a color tone different from that of the incident light in the incident light entrance direction.
JP-A-5-45507 JP-A-6-155893 JP-A-7-128507 Japanese Patent Laid-Open No. 11-167010

  However, with regard to the rainbow sheet having the structure of Patent Document 1, the use of such a structure causes the color of the metal to appear due to the presence of the metal reflection film, and the film becomes gray and loses vividness. In addition, the rainbow color that appears in daylight color is not sharp in hue, lacks in appealing design, and when used for vehicle wrapping etc., it recurs against the headlight illumination of the vehicle at night Since there was no reflection performance, there was a defect that lacked the design and the visibility of the display, which are the original purpose of vehicle wrapping.

Further, if the metal reflective film is removed in order to eliminate the influence of the metal described above, there is a drawback that the rainbow color disappears because the light reflectivity cannot be maintained. Also, if the rainbow film is to be applied to an anti-counterfeit film, when an information layer is formed on the lower layer of the rainbow film to make an anti-counterfeit film, the metal reflective film reflects light almost completely. The display of the information layer located below it is not visible. In addition, if an information layer is formed on the upper layer of the metal reflective film to make a forgery prevention film, the light passes through the information layer until the light passes through the surface film and the glass bulb and is emitted. The existence of the information layer is visible under normal diffused light. In the end, a sheet that uses the retroreflective sheet structure and has a high decorativeness and is sufficiently satisfactory as an anti-counterfeit film has been praised by those skilled in the art despite the strong demand of the market. It was the current situation.

Moreover, since the optical interference material of the said patent document 2 and the said patent document 3 uses the mica for the core material, the material which specularly reflects a part of light of a specific wavelength and permeate | transmits the remaining light as transmitted light However, there is a problem that the amount of interference light decreases and the hue change under diffused light is not sufficient because the reflected light from the core material is reduced. Even under light, the hue change due to specular reflection light was not sufficient. Further, since the interference substance layer of Patent Document 4 is provided below the transparent microsphere, the interference light mainly contributes to the retroreflected light, and colors only the retroreflected light transmitted through the transparent microsphere. Under diffuse light, the color cannot be seen from various directions depending on the viewing point of view, and only the retroreflected light is always colored, especially under night light projection, and multi-color hue changes depending on the viewing direction. There was a problem of not being able to observe enough.

  The present invention solves the above-mentioned problem, and two or more different hues appear due to light interference under daylight color, and retroreflected light has a color different from the hue under daylight color if light is projected onto the sheet at night. And a hue variable retroreflective sheet that exhibits a color different from the retroreflective light on the side opposite to the incident light and a hue variable retroreflective sheet for security that is difficult to counterfeit.

  The hue variable retroreflective sheet of the present invention is a retroreflective sheet having a surface layer composed of at least one layer and a plurality of retroreflective elements positioned below the surface layer, wherein the retroreflective element transmits incident light. A light-interfering colorant that is retroreflected in the direction of the light source, and that at least one of the surface layers changes in color tone depending on the viewpoint, and the surface of the core material is covered with one or more coating layers that are substantially transparent. It is a light-interfering layer added with dispersion, and the incident light is specularly reflected in the opposite direction to the light source, and at least one layer of the retroreflective sheet is a colored layer containing a coloring material that colors retroreflected light. The total light transmittance of the light coherent layer is larger than the total light transmittance of the colored layer, and the retroreflected light and the specularly reflected light exhibit different hues.

  The retroreflective sheet of the present invention is a sheet that expresses two or more different hues due to light interference under daylight color. When light is projected onto the sheet at night, the retroreflective light is a hue under daylight color. Different colors appear. Moreover, it is designed so that a color different from retroreflected light appears in a wider observation angle region on the side opposite to the incident light, and this is a retroreflective sheet that can cope with design diversification and individualization. Furthermore, according to a preferred configuration in which the position of the printing resin layer and the arrangement position of the glass sphere do not overlap, it becomes possible to further improve the forgery prevention effect in addition to the diversification of the colors described above.

  The present invention relates to a retroreflective sheet having a surface layer composed of at least one layer and a plurality of retroreflective elements located under the surface layer, a reflective function for retroreflecting incident light in the direction of the light source, and incident light as a light source. Is equipped with a reflection function that reflects the mirror in the opposite direction, and the retroreflected light and the specularly reflected light are colored in different colors, while maintaining a suitable retroreflective performance and high anti-counterfeiting effect. It has a design and maintains security performance.

  The present invention provides a retroreflective sheet having a surface layer composed of at least one layer and a plurality of retroreflective elements positioned below the surface layer, wherein the retroreflective element has a function of retroreflecting incident light in a light source direction. And at least one of the surface layers is a light which is dispersed and added with a light coherent color material whose color tone changes depending on the viewpoint and the surface of the core material is covered with one or more coating layers which are substantially transparent. Coloring which is a coherent layer and has a function of specularly reflecting incident light in a direction opposite to the light source, and at least one layer of the retroreflective sheet contains a coloring material having a function of coloring retroreflected light In addition, the retroreflected light and the specular reflected light exhibit different hues. As a result, a high design property is exhibited by retroreflected light under nighttime light projection, and an effect of allowing the display to be sufficiently visually recognized not only by the light projecting side but also by the specular reflection light on the opposite side can be obtained.

  The retroreflective sheet is visible under diffused light, and can express two or more hues that differ depending on the viewpoint, thereby exhibiting excellent design properties under daylight.

  The light coherent layer is visible under the diffused light and has a function of developing two or more hues that differ depending on the viewpoint, and the colored layer is located below the light coherent layer. This makes it possible to express specular reflected light that differs from the retroreflected light color not only on retroreflected light but also on the opposite side of the incident light at night. Can be improved.

  By adopting a configuration in which the total light transmittance of the light coherent layer is larger than the total light transmittance of the colored layer, incident light at night can be efficiently transmitted and retroreflected light can be reflected efficiently.

  The total light transmittance of the light coherent layer is larger than the total light transmittance of the colored layer, and the total light transmittance of the light coherent layer is 30% or more, so that the reflected light at night is sharpened. It can be expressed.

  The light interference colorant is a core material having a function of reflecting substantially without transmitting light, and a light interference pigment having a coating layer having a specular reflection function at the interface of any layer, Since the reflection efficiency is improved, the specular light reflected at night can be viewed in a high observation angle region, which is preferable.

  The light coherent layer further contains the colorant in addition to the light coherent colorant, the content of the colorant is α, and the content of the light coherent colorant is β. If α / β is 0.45 or less, the retroreflected light can be colored without impairing the coherence of light under diffused light, which is preferable.

  Among the hues visible under diffused light and the hues of the retroreflective light, at least one color is achromatic, so that when the illumination light is dropped on the retroreflective sheet, the chromatic feeling is particularly clear and suitable. .

  In addition, the hue of at least one of the hues visible under diffuse light and the hue of the retroreflected light are substantially opposite to each other. Is particularly clear and suitable. The opposite hue is a hue circle (red, orange, yellow, yellow-green, green, blue-green, blue, blue-violet, purple, red-purple) divided into 10 basic groups as shown in FIG. For example, when red is used as a reference, the color on the opposite side of the reference color is a complementary color. A color including five colors including two colors on both sides of the complementary color is defined as an opposite hue.

  In the encapsulated lens type retroreflective sheet in which the retroreflective element is encapsulated in a resin, and a focal layer is formed on the back side of the glass sphere, and a metal reflective layer is further formed on the back side of the focal layer. By using a glass sphere having a refractive index of 2.10 or more as the retroreflective element, the optimum focal layer thickness can be reduced, which is suitable for forming the focal layer on concentric circles. At this time, a configuration in which the surface layer and the resin layer are a common layer is also possible.

  In the retroreflective sheet in which the retroreflective element is a glass sphere having a refractive index of 2.10 or more, a focal layer including the glass sphere, and a metal reflective layer formed on the back side of the focal layer, The glass spheres are arranged at random positions in the thickness direction of the focal layer, so that there are glass spheres that are in contact with the surface layer and glass spheres that are not in contact with each other. It exists in a non-constant position. As a result, even if light is incident from a wide-angle position, retroreflection can be performed substantially in that direction, and the observation angle can be widened. Thereby, the retroreflected light of the light projected on the retroreflective sheet at night can be suitably viewed from a wider area.

  The glass sphere includes a glass sphere group B in contact with the surface layer and a glass sphere group A located at a location away from the surface layer, and the glass sphere group A is larger than an observation angle of the glass sphere group B. It has a retroreflective performance at the observation angle, which is preferable because the glass ball group A can exhibit the retroreflective performance at an observation angle larger than the observation angle of the glass ball group B.

  The glass sphere includes a glass sphere group B that is in contact with the surface layer and a glass sphere group A that is located away from the surface layer, and the metal reflective layer of the glass sphere group B is formed at a focus formation position. By making the thickness of the focal layer of the glass bulb group A thinner than the focal layer of the glass bulb group B, the observation of the glass bulb group A is relatively larger than that of the glass bulb group B. Retroreflective performance can be demonstrated at the corners. Thereby, the designability and visibility at night are improved, which is preferable.

  The glass sphere includes a glass sphere group B that is in contact with the surface layer and a glass sphere group A that is located away from the surface layer, and a focal point formed concentrically on the glass spherical surface of the glass sphere group B. The layer has a film thickness that exhibits the highest reflection performance at an observation angle of 0.2 ° and an incident angle of 5 °, and the film thickness of the focal layer of the glass sphere group A is the film of the focal layer of the glass sphere group B. When the glass bulb group A is thinner than the glass bulb group A and has a retroreflective performance at an observation angle larger than that of the glass bulb group B, visibility at night spreads, and an advertising effect is increased.

  The retroreflective element is a glass sphere having a refractive index of 1.80 or more and 2.00 or less, and a hemispherical surface in which a substantially lower hemisphere of the glass sphere is covered with a metal reflection layer is embedded in a resin support sheet. It is preferable that the retroreflective performance at night is further improved by using a capsule lens type in which air is sealed on the surface side of the glass sphere.

  When the retroreflective element is a cube corner type, the retroreflective performance at night at a relatively small observation angle is further improved, which is preferable.

  The hue variable retroreflective sheet is flexible and stretchable and can be attached to a three-dimensional curved surface. As a result, it is possible to attach to various shapes of base materials. The hue variable retroreflective sheet is further JISZ9117. When a 5 mm depth is pushed out by a spherical punch with a radius of 10 mm by an Erichsen film strength tester specified in JISB7729, the sheet is attached to the retroreflective sheet. Since there is no lifting from the aluminum substrate and no abnormalities such as cracks and tears occur, it is suitable for application to three-dimensional curved surface pasting and extrusion molding. The test environmental conditions were in accordance with 65 ± 5% at the environmental conditions of 23 ± 1 ° C. specified in JISZ8703.

  The retroreflective element is a glass sphere having a refractive index of 2.10 or more, and includes a glass sphere fixing layer, a glass sphere and a printing resin layer, a focal layer, and a metal reflection layer in this order, and the printing resin When the layer forms a mark, the glass sphere is arranged in the glass sphere fixing layer, and is observed in the thickness direction of the retroreflective sheet from the surface layer direction, the position of the glass sphere and the printed resin layer Since the metal layer on the back of the retroreflective sheet can be seen through from the surface layer side without being shielded by the glass bulb, the anti-counterfeit logo mark is visually recognized in a metallic style. In addition, the retroreflected light and the specularly reflected light exhibit different hues, which is suitable as a security film having various high design properties.

The present invention is useful as a colorful design film having multiple colors of two or more colors in the daytime, instead of the conventional retroreflective sheet that provided a monotonous design of the same hue throughout the day and night. different retroreflected light is obtained from the daytime color receiving projected light, also, the hue different from the retro-reflected light appearance when viewed the retroreflective sheet from the opposite side of the light projecting side To do. In this way, it has become possible to provide a novel retroreflective sheet that can exhibit multicolor throughout the day and night. In addition, by adjusting the reflection performance of individual glass spheres that realize retroreflection, a group of glass spheres that play a role in maintaining the reflection performance up to a large incident angle at a small observation angle, and a large incidence at a larger observation angle By dividing the glass sphere group that plays the role of maintaining the reflection performance up to the corner and assigning each performance, a retroreflective sheet that retains super-wide angle and is practical can be obtained. This makes it possible to visually recognize the regions of reflected light that shows recursion at night and the reflected light that shows specular reflection almost continuously, making it possible to produce a highly reflective retroreflective sheet throughout the day and night. It becomes.

  In order to express such performance, it has the function of reflecting light, the color tone changes according to the viewpoint, and the surface of the core material is covered with one or more coating layers that are substantially transparent. It is preferable to use a light interference colorant. These light-interfering colorants include mica, titanium, titanium dioxide, aluminum, aluminum oxide, silicon dioxide, iron oxide, glass flakes and other core materials such as iron oxide, tin oxide, titanium dioxide, silicon dioxide, magnesium fluoride. And a light interference pigment coated with one or more layers of chromium, a cholesteric liquid crystal polymer having a spiral structure, and the like. As a particularly preferred example, a material that substantially does not transmit light and reflects is used as the core material, and the core material is substantially transparent and has a function of specular reflection at the interface of one of the layers. Light interference pigments covered with a coating layer of more than one layer can be mentioned, and light interference pigments that reflect about 50% of incident light at any coating layer interface and the remaining about 50% by the core material are used. Then, the interference effect of light becomes the highest, and clear interference light can be visually recognized. As such an optical interference pigment, a titanium oxide coating type using aluminum oxide as a core material and an iron oxide coating type using aluminum oxide as a core material, Xirallic series (manufactured by Merck Japan Ltd.), aluminum as a core material Variochrom (made by BASF) such as a two-layer coating type in which a silicon dioxide coating is further coated with iron oxide, a plate-like iron oxide as a core material, and a silicon oxide coating is further coated with iron oxide, etc., aluminum Examples include CHROMAFLAIR (manufactured by Flex), which is a core material and is further coated with a magnesium fluoride coating with a very thin chromium layer. In addition, various metals or metal alloys can be used as the material that does not substantially transmit light and is used as the core material, but non-metallic reflective materials can also be used. Suitable metallic materials include aluminum, silver, copper, gold, platinum, tin, titanium, palladium, nickel, cobalt, rhodium, niobium, chromium and their compounds, combinations or alloys. Among these, aluminum is preferable from the viewpoint of high reflectivity and ease of use.

  Next, a method for producing such a hue variable retroreflective sheet will be described. In FIG. 1, reference numeral 1 denotes a surface layer of an encapsulated lens type retroreflective sheet. It is preferable that the light-interfering colorant added in a state of being dispersed in the transparent surface layer is dispersed and added to at least one layer of the surface layer. Specific examples of the material of the surface layer used at this time include, for example, a fluoroolefin copolymer, a polyester resin, an alkyd resin, a polyurethane resin, a vinyl resin, a silicone acrylic resin, and an acrylic resin. In addition, a resin having a reactive functional group in the resin and a curing agent and / or a curing catalyst such as an amino resin, an epoxy resin, a polyisocyanate, and a blocked polyisocyanate that react with the reactive functional group can be used. is there. Here, each above-mentioned base resin component may be used independently, and can also be used as a 2 or more types of mixture. As the paint form, any of solvent type, non-aqueous dispersion type, water-soluble type, and water dispersion type can be used, but the solvent type is particularly preferred.

  It is possible to further improve long-term durability by adding an ultraviolet absorber and / or an antioxidant to the composition used to form the surface layer as described above, and adding these to the surface layer. it can.

  As such ultraviolet absorbers, known and commonly used ones can be used, and representative examples include hydroxybenzophenone compounds, salicylic acid ester compounds, oxalic acid anilide compounds, benzotriazole compounds, unsaturated nitrile compounds, and the like. Typical antioxidants include hindered amine compounds, hindered phenol compounds, phosphite compounds, and the like.

More specifically, the surface layer is formed on a biaxially stretched polyethylene terephthalate film that has or has not been subjected to a double-sided easy adhesion treatment for these resins. When the biaxially stretched polyethylene terephthalate film subjected to the double-sided easy adhesion treatment is used, it is used as a part of the surface layer of the final product. It is stripped off before being finished as a product. When the surface layer is composed of two or more layers, each of the above-mentioned synthetic resins may be used alone or in a mixture of two or more for each layer.

  In addition, as a method for forming the surface layer, when a biaxially stretched polyethylene terephthalate film subjected to double-sided easy adhesion treatment is used as part of the surface layer of the final product, the glass described below is provided on one side of the film. After forming the ball fixing layer, the embedding of the glass sphere, the focal layer, and the metal reflection layer in this order, after the bonding of the pressure-sensitive adhesive layer and the release film is finished, the other surface of the film is used for the surface layer described above. It is preferable that the surface layer is completed by sequentially applying and drying the above resins and laminating.

  The light-interfering colorant is dispersed and added to the surface layer. At this time, it is preferable that the light-interfering colorant is dispersedly added to any one or more of the surface layers composed of one or more layers. For example, when the surface layer is composed of one layer, it may be dispersed and added to the surface layer. When the surface layer is composed of two or more layers, it is suitable to be dispersed and added to one or more of the outermost surface layer and / or its lower layer. It is.

  When the light coherent colorant is added in a dispersed manner, when the light coherent colorant is oriented as parallel as possible with respect to the transparent surface layer, the incident light to each particle of the light coherent colorant is constant. Reflects regularly in the direction, and an ideal gloss is obtained.It is preferable that any of the wavelengths of visible light interferes with the thickness of the light-interfering colorant, and an iris color appears. If it is sufficient, light scattering occurs and the iris color does not appear, which is inappropriate. As described above, in order to ideally orient the light interference color material, the thickness of the layer in which the light interference color material is dispersed is set to 80 μm or less, preferably 70 μm or less, more preferably 60 μm or less. The light-interfering colorant uniformly dispersed in the solution of the resin composition for the surface layer can be oriented substantially parallel to the surface layer in the process of evaporation and drying of the solvent of the solution to form a film. Is preferred.

Further, in order to color the retroreflected light during night light projection, the retroreflected light passes through the retroreflective sheet, that is, the light incident from the surface layer passes through the retroreflective element, and further, the encapsulated lens. In the mold, after passing through the focus resin layer, the incident light is retroreflected by the metal reflecting film, and in the cube corner type, the incident light is totally reflected at the place in contact with the air on the back surface of the retroreflective element. It is retroreflected in the direction of the light source through the same path that has passed, but if any layer through which the retroreflected light of the sheet passes is colored, the retroreflected light becomes colored light. At this time, by coloring the layer located below the light coherent layer in which the light coherent color material is uniformly dispersed, two or more hues that differ depending on the viewpoint under the diffused light are expressed, and the incident light It is also possible to have a function of reflecting the surface of the mirror and to have a function of coloring the retroreflected light.

  Although it is possible to contain a colorant for coloring retroreflected light in the light interference layer, in this case, the content of the colorant is α, and the content of the light interference colorant is When β, if α / β is 0.45 or less, more preferably 0.35 or less, it is possible to color retroreflected light without impairing the coherence of light under diffused light, Is preferred.

As the colored layer for coloring the retroreflective light, in the case of an encapsulated lens type retroreflective sheet in which glass spheres are encapsulated in a resin as a retroreflective element, a surface layer, a glass sphere fixing layer, and a focal layer Of these, it is preferable to color at least one layer, and it is more preferable to color at least one of the surface layer and the focus layer because the retroreflected light can be colored efficiently. Further, in a capsule lens type retroreflective sheet in which air is sealed on the surface side of the glass sphere, it is preferable that the surface layer is colored. In addition, when the retroreflective element is a cube corner type, it is preferable to color the surface layer, the retroreflective element, or both layers.

  Furthermore, in the encapsulated lens type retroreflective sheet, since the retroreflected light is retroreflected as the retroreflected light as the incident light that has passed through the glass sphere, most of the retroreflected light is retroreflected without passing through the glass sphere fixing layer. If the glass ball fixing layer is colored, the ratio of matching with the passage path of retroreflected light becomes extremely low, and the diffused light color when viewed with diffused light hardly changes without almost changing the density of the retroreflected light color. The concentration can be improved. Furthermore, the light transmitted through the layer to which the light-interfering colorant is dispersed and added is highly absorbed by the glass ball fixing layer, the background color becomes dark, and the color intensity of the reflected color of the light-interfering colorant Becomes higher, and the saturation is improved, which is preferable.

  As a coloring material for coloring the retroreflected light, a colored paint containing a pigment or a dye can be used as a paint for forming each layer. Examples of pigments used in obtaining such a colored paint include organic pigments such as phthalocyanine blue, phthalocyanine green, quinacridone red, hansa yellow, perinone orange, iron oxide red, iron oxide yellow, titanium white, and cobalt blue. Such known inorganic pigments are used.

  The amount of the light coherent color material added to the light coherent layer is 30% or more, preferably, the total light transmittance transmitted through all the light coherent layers dispersedly added with the light coherent color material, If kept at 40% or more, more preferably 50% or more, it is suitable for efficiently returning the retroreflected light colored when the retroreflective sheet is illuminated at night and maintaining the retroreflective performance. is there.

  Furthermore, it is preferable that the total light transmittance of the light interference layer is larger than the total light transmittance of the colored layer that colors the retroreflected light, in order to obtain clear retroreflected light.

  Furthermore, the important point in coloring retroreflected light is that the color tone changes depending on the viewpoint described above, and is visible under the diffused light of a light coherent color material having excellent transparency, and two or more colors that differ depending on the viewpoint. In order to improve the design and clarity of the colored retroreflected light, it is very preferable that at least one of the hues of the color and the hue of the retroreflected light be achromatic. .

  Further, the color tone changes depending on the viewpoint described above, and is visible under the diffused light of the light coherent color material having excellent transparency, and the hue of at least one color out of two or more hues different depending on the viewpoint and the retroreflection A hue substantially opposite to that of light is extremely suitable for enhancing the design and clarity of the colored retroreflected light. The opposite hue described here is, as already defined, a hue circle (red, orange, yellow, yellow-green, green, blue-green, divided into 10 basic hue circles as shown in FIG. For example, when red is used as a reference, the color on the opposite side of the reference color is a complementary color, but five colors including two colors on each side of the complementary color are included. The opposite color is the opposite hue.

  Next, the encapsulating lens type retroreflective sheet in which the glass sphere is encapsulated in the resin as the retroreflective element will be described with respect to the production method from the formation of the glass sphere fixing layer to the final product. When a biaxially stretched polyethylene terephthalate film subjected to double-sided easy adhesion treatment is used, a glass sphere fixing layer is formed on the polyethylene terephthalate film. When the biaxially stretched polyethylene terephthalate film not subjected to the easy adhesion treatment is used, a glass sphere fixing layer is formed on the surface layer on which the surface layer resin composition is laminated. Typical examples of the paint used as the glass ball fixing layer in this case include a fluoroolefin copolymer, a polyester resin, an alkyd resin, a polyurethane resin, a vinyl resin, a silicone acrylic resin, and an acrylic resin. Examples include a resin and a resin having a reactive functional group in the resin and a curing agent and / or a curing catalyst such as an amino resin, an epoxy resin, a polyisocyanate, and a blocked polyisocyanate that react with the reactive functional group. . Here, each above-mentioned base resin component may be used independently, and can also be used as a 2 or more types of mixture. As the paint form, any of a solvent type, a non-aqueous dispersion type, a water-soluble type, and a water dispersion type can be used, but a solution type is particularly preferable.

  Next, the glass sphere constituting the encapsulating lens type retroreflective sheet has a refractive index of 2.10 or more, preferably 2.10 to 2.40, more preferably 2.15 to 2.35. used. The particle diameter of the glass sphere is 5 to 300 μm, preferably 20 to 100 μm, and more preferably 40 to 70 μm. When the particle diameter of the glass sphere is less than 5 μm, the required film thickness of the focal layer becomes extremely thin, and it becomes difficult to control the film thickness. On the other hand, if the thickness exceeds 300 μm, the required focal layer thickness becomes extremely large, and the resin flows in the heating process during the formation of the focal layer, so that the resin is formed concentrically with the glass sphere diameter. Have difficulty. When the refractive index is less than 2.10, the required focal layer thickness becomes extremely large, and it is difficult to form a resin concentrically with the spherical diameter of the glass sphere. Moreover, when manufacturing the glass sphere of refractive index exceeding 2.4, it is very difficult to prevent crystallization and to produce a transparent glass sphere accurately and industrially.

  Typical examples of the paint used for forming the focal layer include those having a base polymer component of polyurethane resin, polyvinyl acetal resin, acrylic resin, alkyd resin, and polyester resin. These can be used as a non-crosslinking type, or can be used as a thermosetting type by blending a curing agent such as amino resin, epoxy resin, polyisocyanate, or blocked polyisocyanate. As the form of the coating material for the focal layer, various types similar to the coating material for the glass sphere fixing layer can be used.

  A method for producing a retroreflective sheet (B type) in which the wide-angle characteristics of the encapsulated lens type retroreflective sheet (A type) are further improved will be described below.

  The A type and the B type include forming a metal reflective layer on the focal layer and laminating an adhesive layer and a release material on the metal reflective layer.

  Moreover, when producing a surface layer for both the A type and the B type, when using a biaxially stretched polyethylene terephthalate film in which a process film has been subjected to easy adhesion treatment such as corona discharge treatment or resin coating on both sides, the film It is also possible to form a surface layer on one side and use it as two or more surface layers.

  In the case of the B type, a focal layer resin solution in which glass spheres are dispersed is applied onto the surface layer and dried by heating, so that 50 to 90% by mass of the glass spheres are in contact with the surface layer. However, there is a difference in the time of each glass sphere that settles on the surface layer, so that the glass sphere that touches the surface layer first does not sink into the surface layer anymore. It is important to stop the settling of the glass sphere at the position in contact with the layer.

  The necessary condition for this is to suppress the settling of the glass sphere by advancing the hardening of the focal layer. However, as described above, a time difference occurs in the settling of the glass sphere, so that the surface layer is first reached. In order to prevent further sinking of the glass sphere, it is necessary that the surface layer has resistance to prevent the glass sphere from sinking. The first performance required for the resistance is that the surface layer is not dissolved by contact with the solvent of the focal layer solution, and the glass is softened at a temperature when the focal layer resin is dried and cured. The surface layer is required to have heat resistance so that the sphere does not sink into the surface layer.

  This is because if the glass sphere further sinks into the surface layer, the individual positions of the glass spheres of 50 to 90% by mass responsible for the reflection performance at a relatively small observation angle shift and the desired reflection performance value cannot be achieved. . As a result of various studies, the present inventors have achieved that the desired reflection performance can be achieved if the sinking into the surface layer can be controlled at 10% or less of the particle diameter of the glass sphere, and the glass sphere can be concentrically focused. It has been confirmed that a layer can also be formed.

  A metal reflective layer is provided on the focal layer. At this time, the metal reflective layer can be formed of the following metal, and its thickness varies depending on the metal used, but is 5 to 200 nm, preferably 10 to 100 nm. It is. When the thickness of the metal reflective layer is less than 5 nm, the concealment property of the metal reflective layer is insufficient, so that the purpose as the reflective layer cannot be achieved. Conversely, when the thickness exceeds 200 nm, the metal reflective layer has cracks. It is not preferable because it is easy to enter and the cost is increased. The method for providing the metal reflective layer is not particularly limited, and a normal vapor deposition method, sputtering method, transfer method, plasma method, or the like can be used. In particular, vapor deposition and sputtering are preferably used from the viewpoint of workability. The metal used in forming the metal reflective layer is not particularly limited, and examples thereof include aluminum, gold, silver, copper, nickel, chromium, magnesium, zinc, and the like. In view of workability, ease of forming the metal reflective layer, light reflection efficiency, durability and the like, aluminum, chromium or nickel is particularly preferable. The metal reflective layer may be formed of an alloy composed of two or more metals.

  In addition, the drying conditions after the coating application for forming the surface layer and the focal layer including the glass sphere are as follows: the type of base resin used as a coating material, the type of reactive functional group in the base resin, the curing agent It is determined so that a desired state can be established as appropriate according to the type, the type and addition amount of the curing catalyst, and the type of solvent.

  Examples of the resin constituting the pressure-sensitive adhesive layer of the present invention include rubber resins such as acrylic resins, natural rubber, and synthetic rubber. In particular, as an acrylic resin, a tackifier and a cohesive force are further added to a high molecular acrylic resin containing at least one of an acrylic ester copolymer and an acrylic prepolymer as a main component or the acrylic resin. A modified acrylic resin to which a monomer to be added is added is preferable.

  A manufacturing method for further adding security performance to the hue variable retroreflective sheet of the present invention will be described below. A method for producing a variable hue retroreflective sheet in which a glass sphere fixing layer, a glass sphere and a printed resin layer, and a focal layer are sequentially laminated on the surface layer, and a metal reflective layer is formed on the focal layer. The surface layer and the glass sphere fixing layer are sequentially laminated, and a predetermined anti-counterfeit logo mark is printed on the back side of the glass sphere fixing layer as a printing resin layer. The resin composition as a component is cured, and then heated to a temperature at which adhesiveness develops in the glass sphere fixing layer, and the glass sphere is embedded in the glass sphere fixing layer. Since the glass sphere is not embedded in the printed part because the adhesiveness is not expressed, a focus layer is further laminated, and a metal reflective layer is further formed on the focus layer, thereby providing a hue with added security. It can produce variations retroreflective sheet. By this method, when the glass sphere is embedded in the glass sphere fixing layer, the glass sphere is not embedded in the printed portion, so that it is not shielded by the glass sphere, and from the surface layer side of the back surface of the retroreflective sheet. Since the metal layer can be seen through, the anti-counterfeit logo mark can be visually recognized in a metallic style.

  Further, as the retroreflective element, a glass sphere having a metal reflective layer in the hemispherical portion, a cube corner type retroreflective element, or the like can be used. In addition, as described above, the retroreflective element is held on at least one of the resin support sheet and the cover film. Here, the hemispherical surface of the glass sphere covered with the metal reflective layer is The capsule lens type retroreflective sheet that is held so as to be buried in the resin support sheet will be exemplified. However, in the case of a cube corner type retroreflective element, it is held by a cover film.

  First, a metal reflection layer is formed on the hemispherical portion of the glass sphere. As shown in FIG. 4, a plurality of the glass spheres 12 are embedded on the surface of the polyethylene glass sphere temporary fixing layer 17 laminated on the polyester film 18 as the first film. In order to embed, the laminated body of the glass sphere temporary fixing layer 17 and the polyester film 18 is heated to soften the polyethylene, and the glass sphere 12 is submerged in the glass sphere temporary fixing layer 17. The particle diameter of the glass sphere is, for example, about 5 μm to 300 μm, preferably about 20 μm to 90 μm, and more preferably 40 μm to 80 μm. The refractive index of the transparent sphere is, for example, about 1.8 to 2.1, preferably about 1.9 to 1.95, and more preferably 1.92 to 1.93. Next, the metal reflective layer 13 is formed on the hemispherical surface of the glass sphere 12 exposed from the surface of the glass sphere temporary fixing layer 17 by vapor deposition. Examples of the material of the metal reflective layer 13 include aluminum, gold, silver, copper, nickel, chromium, tin, alloys containing these metals, or materials having excellent light reflectivity, such as titanium oxide and titanium nitride. Aluminum is preferred. Next, as shown in FIG. 5, a primer layer 15 is formed on a polyester film 16 as a separate supporting film, and a resin support sheet 14 is formed thereon. A type that does not have the primer layer 15 may omit the step of preparing the primer layer. Next, as shown in FIGS. 6 to 7, the resin support sheet 14 is placed along the glass sphere temporary fixing layer 17, and the resin support sheet 14 is pressed against the surface of the glass sphere temporary fixing layer 17. At this time, the glass sphere 12 whose substantially hemispherical surface is covered with the metal reflecting layer 13 is embedded in the resin support sheet 14. Next, as shown in FIG. 8, the glass ball temporary fixing layer 17 is peeled off together with the polyester film 18 from the surface of the resin support sheet 14. At this time, the glass sphere 12 is transferred to the resin support sheet 14 and held in a state where the hemisphere is buried by the resin support sheet 14. Next, as shown in FIGS. 9 to 10, the resin support sheet surface is covered with a separately prepared surface layer film 1, and thermocompression-bonding is performed with a patterned embossing roll 19, and the resin support sheet 14 and the surface layer film 1 are formed. A capsule lens type in which the hemispherical surface, in which the substantially lower hemisphere is covered with the metal reflective layer 13, is held so as to be embedded in the resin support sheet 14, and air is sealed on the surface side of the glass sphere. A retroreflective sheet can be produced.

  In the case of the capsule lens type retroreflective sheet, the surface layer film corresponds to the surface layer of the present invention, and the light coherent colorant and the colorant added to the light coherent layer and the colored layer are all described above. Although it is dispersed and added to the surface layer film, these production methods, configurations and the like may be carried out in accordance with the encapsulated lens type retroreflective sheet described above.

  Furthermore, in the cube corner type, as shown in FIG. 11, the surface layer film 1 corresponds to the surface layer of the present invention as in the capsule lens type retroreflective sheet. Coloring materials such as dyes and pigments can be added to color the retroreflected light. In FIG. 11, 14 is a resin support sheet, 16 is a polyester film, and 19 is an embossing roll.

  As another manufacturing method, in order to color the above-described retroreflective light, the retroreflective sheet in which a colorant is added in advance to any layer constituting the above-described retroreflective sheet, and the light interference color The hue variable retroreflective sheet of the present invention can also be produced by laminating a surface layer film having a light interference layer to which a material is dispersed and added using an adhesive, an adhesive or the like.

  Hereinafter, the present invention will be described by way of examples. In the following examples, the “part” and “%” numerical values indicating the mixing ratio mean parts by mass or mass% unless otherwise specified. The same reference numerals in the drawings denote the same parts or members unless otherwise specified.

Example 1
FIG. 1 is a cross-sectional view of a hue variable retroreflective sheet according to the present embodiment, in which 1 is a surface layer, 2 is a glass sphere fixing layer, 3 is a focal layer, 4 is a glass sphere, 5 is a metal reflective layer, and 6 is An adhesive layer 7 is a release material.

  The surface layer 1 shown in FIG. 1 is produced. The formulation example of the resin composition for the surface layer 1-1 is about 100 parts of Fluonate K-700 (manufactured by Dainippon Ink & Chemicals, Inc., mass average molecular weight of about 70,000, solid content hydroxyl value of 48, nonvolatile content of about 50%). About 15 parts of Sumimar M-100C (Methylated melamine resin manufactured by Sumitomo Chemical Co., Ltd., about 100% non-volatile content) as a curing agent, and about about Neicure 3525 (manufactured by KING INDUSTRIES, dinonylnaphthalenedisulfonic acid) as a curing catalyst 1.3 parts of a resin composition containing about 1 part of tinuvin 900 (ultraviolet absorber) and about 1 part of tinuvin 292 (antioxidant) on a polyester film that has not been subjected to double-sided easy adhesion treatment as a carrier film It was applied so that the dry film thickness was about 20 μm, and was heat-dried at about 140 ° C. for about 10 minutes to obtain surface layer 1-1. Subsequently, a surface layer 1-2 (light interference layer) in which a light interference pigment is dispersed and added is prepared on the surface layer 1-1 prepared above. An example of blending the resin composition is Bernock D6-439. About 100 parts of alkyd resin (Dainippon Ink Chemical Co., Ltd., solid content hydroxyl value 140, non-volatile content 80%), Vernock DN-980 (Dainippon Ink Chemical Co., Ltd. polyisocyanate prepolymer, non-volatile content 75) as a curing agent %) And a resin composition of 3.5 parts of Variocrm Magic Gold L 1400 (manufactured by BASF, optical interference pigment) was applied so that the dry film thickness was about 20 μm, and about 140 ° C. Heat drying was performed for 10 minutes to obtain a surface layer 1-2 (light interference layer). Subsequently, a surface layer 1-3 (colored layer) for coloring retroreflected light is produced on the surface layer 1-2 (light interference layer) produced as described above, but the formulation example of the resin composition is Beckolite M. -6401-50 (Dainippon Ink Chemical Co., Ltd., solid content 60%) 100 parts, Super Becamine J-820-60 (Dainippon Ink Chemical Co., Ltd., butylated melamine resin, solid content 60%) 20 Parts, 1 part of Becamine P-198 (Dainippon Ink Chemical Co., Ltd., curing catalyst), DICTON BLUE HD-6272 (Dainippon Ink Chemical Co., Ltd., processed pigment for oil paint, pigment concentration 10%) 9.0 Part, DICTON RED HD-6112A (Dainippon Ink & Chemicals Co., Ltd., processed pigment for oil-based paint, pigment concentration 6%), 0.2 parts, is applied so that the dry film thickness is about 20 μm About 1 Heat drying was performed at 40 ° C. for about 10 minutes to obtain surface layer 1-3 (colored layer).

  Next, 100 parts of Beckolite M-6401-50, 10 parts of Super Becamine J-820-60, Becamine P-198 (produced by Dainippon Ink & Chemicals, Inc., cured) It was adjusted from 0.5 part of accelerator, acid value 400) and 10.0 parts of Polycizer W-360-ELS (manufactured by Dainippon Ink & Chemicals, Inc., polymer plasticizer). This composition was applied onto the surface layer 1-3 (colored layer) so as to have a dry film thickness of about 70% of the diameter of the glass sphere, and dried at room temperature to volatilize the solvent. Thereafter, glass spheres were embedded and further dried at 140 ° C. for 5 minutes.

  As the glass sphere, a high refractive index glass sphere having a refractive index of 2.23 mainly composed of titanium oxide and a particle diameter of 55 to 65 μm was used.

  The resin composition for the focal layer was prepared from 100 parts of polyurethane resin, Bernock L8-974 (Dainippon Ink Chemical Co., Ltd.) and 10 parts of Superbecamine J-820-60. This composition was applied onto the glass sphere so as to have a dry film thickness of about 14 μm, dried at 100 ° C. for 10 minutes, and further heated and dried at 140 ° C. for 10 minutes.

  Aluminum was used as the metal reflection layer, and the hue variable retroreflective sheet was prepared by depositing it on the focal layer by vacuum deposition so that the film thickness was 80 nm.

  100 parts by mass of acrylic pressure-sensitive adhesive fine tack SPS-1016 (manufactured by Dainippon Ink & Chemicals, Inc.) and a crosslinking agent DN-750- on the surface of the metal reflection layer of the reflection sheet thus obtained and a silicone-coated release paper 45 (manufactured by Dainippon Ink & Chemicals, Inc.) 1 mass part of the mixed solution was applied and dried, and the adhesive layer having a thickness of about 35 μm was pasted, and then the polyester film as the carrier film was peeled off to obtain the final product did.

  At this time, the total light transmittance of the light interference layer was 72%, and the hue of the light interference pigment changed from gold to gray (achromatic) under diffused light. The total light transmittance of the colored layer was 29%.

The hue-variable retroreflective sheet produced in this example changed from gold to blue-violet depending on the viewpoint under diffused light, and a hue with a very rich design was visible. In addition, when the light is illuminated at night, the retroreflected light shines pure blue, and due to the interference effect of the specular reflection light by the light interference pigment, a clear interference color is visible from red purple to gold in a wider observation angle range. In addition, there is an excellent decorative effect that could not be expressed with a conventional marking film or a retroreflective sheet, and in addition, an article using the hue variable retroreflective sheet was used to have a prominent design. Sex was expressed and the eye-catching effect was high.

  Further, the final product is JISZ9117. When it is affixed to an aluminum substrate with a thickness of 1 mm specified in the test method and extruded to a depth of 8 mm with a spherical punch with a radius of 10 mm by an Erichsen film strength tester specified in JIS B7729, the retroreflective sheet has There was no lift from the aluminum substrate, and no abnormalities such as cracks and tears occurred.

(Example 2)
FIG. 3 is a cross-sectional view of the hue variable retroreflective sheet of this example, in which 1 is a surface layer, 2 is a glass sphere fixing layer, 3 is a focal layer, 4 is a glass sphere, 5 is a metal reflective layer, and 6 is An adhesive layer, 7 is a release material, and 8 is a printing resin layer.

  Same as Example 1 except that Variocrm Magic Gold L 1400 of surface layer 1-2 (light interference layer) in Example 1 is changed to 7.0 parts of CHROMAFLAIR GOLD / SILVER (manufactured by Flex, light interference pigment). Thus, a surface layer was produced.

  Next, 5 parts of Beckolite M-6401-50, 1.5 parts of Superbecamine J-820-60, 0.5 parts of Becamine P-198, olefinic special resin composition for glass sphere fixing layer Copolymer Elvalloy 551 (manufactured by Mitsui DuPont Polychemical Co., Ltd., 25% THF solution), acrylic resin (made of styrene / methyl methacrylate / soft monomer, Tg of 50 ° C., hydroxyl value of about 14), 15 parts (solid content) 45%) and an epoxy plasticizer O-130P (manufactured by Asahi Denka Kogyo Co., Ltd.). This composition was coated on the surface layer 1-3 (colored layer) with a glass sphere fixed layer so that the dry film thickness was about 30 μm, and heated at 70 ° C. for 5 minutes to volatilize the solvent. The probe tack strength at this time was 3 gf. The probe tack is a probe tack tester (according to ASTM D-2979 manufactured by Nichiban Co., Ltd.), using a 5 mmφ stainless steel surface finish AA # 400 polished and a mirror-like probe rod, with a peeling speed of 1 cm / sec and a measurement load of 9. It is tack strength measured under test conditions of 8 ± 0.1 g (made of brass), contact time 1 second, measurement environment 23 ± 2 ° C., and relative humidity 65 ± 5%.

  In the above state, the sheet was rolled up, and a forgery prevention logo mark was printed on the glass ball fixing layer using a gravure printing machine in the next step. At this time, the resin composition was compounded with hydroxyl group-containing acrylic resin (Dainippon Ink & Chemicals, solid content 45%, solvent xylene, butyl acetate, toluene, hydroxyl value 45), isocyanate prepolymer as curing agent. (Dainippon Ink Chemical Co., Ltd., solid content 75%, solvent is ethyl acetate, NCO content 15%) is 23 parts and butyl cellosolve acetate 10 parts.

  Thereafter, aging was carried out at room temperature for about 1 week to advance the curing of the printed part. Thereafter, the printed product is heated at 120 ° C. for 1 minute to cause the glass sphere fixing layer to exhibit stickiness, and glass spheres (refractive index 2.23 mainly composed of titanium oxide, high particle size of 67 to 73 μm). (Refractive index glass sphere) 3 was embedded in the glass sphere fixing layer, and further dried at 140 ° C. for 5 minutes. The resin composition for the focal layer 4 was prepared from 100 parts of polyurethane resin, Bernock L8-974 (Dainippon Ink Chemical Co., Ltd.) and 10 parts of Superbecamine J-820-60.

  This composition was applied onto the glass sphere so as to have a dry film thickness of 16 μm, dried at 100 ° C. for 10 minutes, and further dried at 140 ° C. for 10 minutes.

  Subsequent steps were performed in the same manner as in Example 1 to complete the hue variable retroreflective sheet.

  At this time, the total light transmittance of the light interference layer was 87%, and the hue of the light interference pigment changed from gold to silver (achromatic) under diffused light.

The hue-variable retroreflective sheet produced in this example changed from a red gold color to a green gold color depending on the viewpoint under diffused light, and a hue with a very rich design could be visually recognized. In addition, when illuminated at night, the retroreflected light shines in pure blue, and the observation angle region where the clear interference color is wider due to the interference effect of the light reflected specularly by the outermost layer surface of the light interference pigment and the core material. It is visible from magenta to gold and has an excellent decorative effect that could not be expressed with conventional marking films and retroreflective sheets. In addition, the hue variable retroreflective sheet is used for pasting. The finished product exhibited a prominent design and a high eye-catching effect.

  Furthermore, if the completed retroreflective sheet is visually recognized from the surface side, the anti-counterfeit logo mark can be visually recognized in a metallic style, and if the retroreflective sheet is irradiated with a night light, except for the logo mark part The retro-reflective effect brightly shines, the logo mark portion is dark, and the anti-counterfeit logo mark is clearly visible due to the contrast. As a result, the retroreflective sheet was not only excellent in design, but also exhibited an excellent effect as a forgery prevention film.

(Example 3)
FIG. 2 is a cross-sectional view of the hue variable retroreflective sheet according to the present embodiment, wherein 1 is a surface layer, 3 is a focal layer, 4, 4a and 4b are glass spheres, and 4a is a glass sphere not in contact with the surface layers. A glass sphere of group A, 4b is a glass sphere of glass sphere group B in contact with the surface layer, 5 is a metal reflective layer, 6 is an adhesive layer, and 7 is a release material. L1 and L2 represent the dry film thickness of the focal layer from the top of the glass sphere, and L1> L2.

  A surface layer was produced in the same manner as in Example 1 except that the surface layer 1-1 was changed as follows. Formulation of the resin composition for the surface layer 1-1 is fluorinate K-703 (fluorine resin, manufactured by Dainippon Ink & Chemicals, Inc., mass average molecular weight 40000, solid content hydroxyl value 72, nonvolatile content about 60%). About 100 parts, Vernock DN-950 (curing agent) is about 25 parts, Tinuvin 900 (ultraviolet absorber) is about 1 part, and Tinuvin 292 (antioxidant) is about 1 part.

Next, the following glass sphere-dispersed resin solution was applied as a focal layer on the surface layer 1-3 (colored layer).
(1) Polyvinyl butyral resin solution: 75.0 parts (degree of polymerization: 680, polyvinyl alcohol unit 23 mass%, glass transition point 66 ° C., solid content 21%, n-butanol / toluene 1: 1)
(2) Superbecamine J-820-60: 3.3 parts (Dainippon Ink & Chemicals, butylated melamine resin, solid content 60%)
(3) Becamine P-198: 0.2 part (manufactured by Dainippon Ink & Chemicals, Inc., curing accelerator, acid value 400)
(4) BYK-053: 0.5 part (Bic Chemie Japan, alkyl vinyl ether copolymer, antifoaming agent)
(5) Polycider W-360-ELS: 7.0 parts (Dainippon Ink Chemical Co., Ltd., polymer plasticizer)
(6) Toluene: 7.6 parts (7) n-butanol: 7.6 parts (8) Glass sphere: 68.0 parts (center particle size 50 μm, contained 90% or more within ± 10 μm,
Refractive index 2.25 ± 0.05)
The viscosity of the blended resin (excluding glass spheres) paint was 1900 mPa · s.

  The glass sphere-dispersed resin solution is a WET film so that a focal layer is formed at the focal position of the glass sphere in contact with the surface layer 1-3 (the dry film thickness from the apex of the glass sphere is about 13 to 14 μm). The thickness was adjusted and applied on the surface layer 1-3.

  Thereafter, the film was dried at room temperature for about 5 minutes, followed by drying at 100 ° C. for 5 minutes, followed by further heat drying at 140 ° C. for 10 minutes to cure the focal layer resin.

  Next, aluminum was used as the metal reflective layer, and was deposited on the focal layer by vacuum deposition so as to have a thickness of 80 nm.

  100 parts by mass of acrylic adhesive Finetack SPS-1016 (manufactured by Dainippon Ink & Chemicals, Inc.) and a cross-linking agent DN-750-45 (Dainippon Ink Chemical Co., Ltd.) (Made by Kogyo Co., Ltd.) 1 part by mass of the mixed solution was applied and dried at 100 ° C. for 5 minutes to prepare a 50 μm thick adhesive layer.

  Subsequently, the pressure-sensitive adhesive layer surface and the above-described metal reflective layer surface were bonded together, and then the polyester film as the supporting film was peeled to obtain a final product. At this time, the glass sphere in contact with the surface layer 1-3 was about 67%.

  Furthermore, the focal layer did not dissolve when the intermediate product was immersed in each solvent for 1 minute in toluene, 1 minute in xylene, and 10 minutes in methanol before forming the metal reflective layer.

The hue-variable retroreflective sheet produced in this example changed from gold to blue-violet depending on the viewpoint under diffused light, and a hue with a very rich design was visible. Also, when the light is illuminated at night, the retroreflected light shines in pure blue, and even if the line of sight is greatly deviated from the light source, the retroreflected light is visible because of the wide-angle reflectivity, and from the pure blue retroreflected light Excellent decoration that could not be expressed with conventional marking film or retroreflective sheeting, even when the position or viewpoint of the light source is changed, even when the position or viewpoint of the light source is changed. In addition, the article using the hue variable retroreflective sheet with sticking color exhibited prominent design and high eye-catching effect.

Example 4
In Example 1, a hue variable retroreflective sheet was produced in the same manner as in Example 1 except that the resin composition for the glass sphere fixing layer was changed as follows.

  The resin composition comprises 100 parts of Beckolite M-6401-50, 10 parts of Super Becamine J-820-60, 0.5 part of Becamine P-198, 10.0 parts of Polycizer W-360-ELS. , Adjusted from 10.0 parts of DICTON BLUE HD-6272 and 0.7 parts of DICTON RED HD-6112A.

The color-tunable retroreflective sheet produced in this example changes from gold to blue-violet depending on the viewpoint under diffused light, and the light transmitted through the light interference layer by the effect of the pigment dispersed and added to the glass sphere fixing layer is Since the light interference layer is absorbed by the pigment and the background of the light interference layer becomes dark, the light interference color is very clearly visible in a hue with a rich design. In addition, when the light is illuminated at night, the retroreflected light shines pure blue, and due to the interference effect of the specular reflection light by the light interference pigment, a clear interference color is visible from red purple to gold in a wider observation angle range. In addition, there is an excellent decorative effect that could not be expressed with a conventional marking film or a retroreflective sheet, and in addition, an article using the hue variable retroreflective sheet was used to have a prominent design. The eye-catching effect was outstanding.

  Further, the final product is JISZ9117. When it is affixed to an aluminum substrate with a thickness of 1 mm specified in the test method and extruded to a depth of 8 mm with a spherical punch with a radius of 10 mm by an Erichsen film strength tester specified in JIS B7729, the retroreflective sheet has There was no lift from the aluminum substrate, and no abnormalities such as cracks and tears occurred.

(Example 5)
In Example 1, a hue variable retroreflective sheet was produced in the same manner as in Example 1 except that the resin composition of the surface layer 1-2 (light interference layer) was changed as follows.

  The blending example of the resin composition is about 100 parts of Bernock D6-439, about 82 parts of Bernock DN-980 (Dainippon Ink Chemical Co., Ltd. polyisocyanate prepolymer, non-volatile content 75%) as a curing agent, Variocrm Magic Gold L 1400 (manufactured by BASF, optical interference pigment) 3.5 parts, DICTON BLUE HD-6272 (manufactured by Dainippon Ink and Chemicals, processed pigment for oil paint, pigment concentration 10%) 7.0 parts.

The hue-variable retroreflective sheet produced in this example changed from yellowish green to blue-green depending on the viewpoint under diffused light, and a hue with a very rich design could be visually recognized. In addition, when the light is illuminated at night, the retroreflected light shines pure blue, and due to the interference effect of the specular reflection light by the light interference pigment, a clear interference color is visible from red purple to gold in a wider observation angle range. In addition, there is an excellent decorative effect that could not be expressed with a conventional marking film or a retroreflective sheet, and in addition, an article using the hue variable retroreflective sheet was used to have a prominent design. The eye-catching effect was outstanding.

(Comparative Example 1)
The following resin composition was applied on a polyester film that had not been subjected to double-sided easy adhesion treatment so that the dry film thickness was about 40 μm, followed by heat drying at about 140 ° C. for about 10 minutes to obtain a surface layer. Examples of the resin composition include 100 parts of Beckolite M-6401-50 (Dainippon Ink Chemical Co., Ltd., solid content 60%), Super Becamine J-820-60 (Dainippon Ink Chemical Co., Ltd.). 20 parts of butylated melamine resin, solid content 60%), 1 part of Becamine P-198, 9.0 parts of DICTON BLUE HD-6272, and 0.2 parts of DICTON RED HD-6112A.

  Next, 100 parts of Beckolite M-6401-50, 10 parts of Super Becamine J-820-60, 0.5 part of Becamine P-198, Polycizer W-360 -Adjusted from 10.0 parts ELS, 10.0 parts DICTON BLUE HD-6272, 0.7 parts DICTON RED HD-6112A.

  This composition was applied on the surface layer so as to have a dry film thickness of about 70% of the diameter of the glass sphere, and after drying at room temperature to evaporate the solvent, the glass sphere was embedded, Further, drying was performed at 140 ° C. for 5 minutes.

  As the glass sphere, a high refractive index glass sphere having a refractive index of 2.23 mainly composed of titanium oxide and a particle diameter of 55 to 65 μm was used.

  The resin composition for the focal layer was prepared from 100 parts of polyurethane resin, Bernock L8-974 and 10 parts of Superbecamine J-820-60. This composition was applied onto the glass sphere so as to have a dry film thickness of about 14 μm, dried at 100 ° C. for 10 minutes, and further heated and dried at 140 ° C. for 10 minutes.

  Aluminum was used as the metal reflective layer, and a retroreflective sheet was prepared by depositing it on the focal layer by vacuum deposition so as to have a film thickness of 80 nm.

  100 parts by weight of acrylic pressure-sensitive adhesive fine tack SPS-1016 (manufactured by Dainippon Ink & Chemicals, Inc.) and crosslinking agent DN-750- on the surface of the metal reflective layer of the reflective sheet thus obtained and on the silicone-coated release paper 45 (manufactured by Dainippon Ink & Chemicals, Inc.) 1 part by weight of the mixed solution was applied and dried, and the adhesive layer having a thickness of about 35 μm was bonded together, and then the polyester film as the carrier film was peeled off to obtain the final product did.

In the retroreflective sheet produced in this comparative example, under diffused light, only the blue hue was visually recognized even when the viewpoint was changed, and the other hues were not visually recognized. When the light was irradiated at night, the retroreflected light shined blue and the specularly reflected light looked blue as well, but the hue was dark and did not shine. The retroreflected light under the diffused light and the light was also inferior in the decoration effect because it was only blue.

(Comparative Example 2)
The following resin composition was applied onto a polyester film that had not been subjected to double-sided easy adhesion treatment so that the dry film thickness was about 40 μm, and heat-dried at about 140 ° C. for about 10 minutes to produce a light interference film.

  The blending example of the resin composition is as follows: Bernock D6-439 (Dainippon Ink & Chemicals, Inc., alkyd resin, solid content hydroxyl value 140, non-volatile content 80%), about 100 parts, and curing agent Vernock DN-980 (Dainippon) About 82 parts of polyisocyanate prepolymer manufactured by Ink Chemical Industries, Ltd. (non-volatile content: 75%) and 3.5 parts of Variocrm Magic Gold L 1400 (manufactured by BASF, optical interference pigment).

  On the light interference film thus obtained and silicone-coated release paper, 100 parts by weight of acrylic adhesive Finetack SPS-1016 (manufactured by Dainippon Ink and Chemicals) and a crosslinking agent DN-750-45 (Dainippon Ink) (Chemical Industry Co., Ltd.) An adhesive layer having a thickness of about 35 μm prepared by applying and drying 1 part by weight of the mixed solution was bonded together, and then the polyester film as the carrying film was peeled to obtain the final product.

  Thereafter, the release paper was removed and attached to a black painted aluminum plate.

  The light coherent sheet produced in this comparative example changed from golden to gray depending on the viewpoint under diffused light, but when the light was irradiated at night, only the specular reflection light of the light coherent sheet appeared golden and the light was projected. From the side, it was inferior in the decorative effect, only through the light-interfering sheet and the black coating of the base was visible.

  The present invention is a hue variable retroreflective sheet that can be applied to various uses such as a car license plate, a security sheet, an advertisement signboard, a display body, a vehicle wrapping sheet, a toy, a cosmetic container, and a mobile phone.

It is sectional drawing of the hue variable type retroreflection sheet applied to the enclosure lens type retroreflection sheet in Example 1 of this invention. It is sectional drawing of the hue variable type retroreflection sheet applied to the wide-angle retroreflection sheet in Example 3 of this invention. It is sectional drawing of the hue variable type retroreflection sheet applied to the retroreflection sheet for security in Example 2 of this invention. It is sectional drawing which shows the manufacturing process of the hue variable type retroreflection sheet applied to the capsule lens type retroreflection sheet in one Example of this invention. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows a manufacturing process equally. It is sectional drawing which shows the manufacturing process of the hue variable type retroreflection sheet applied to the cube corner type retroreflection sheet in one Example of this invention. It is a hue ring diagram which shows the relationship between a reference | standard hue and an opposite hue used in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface layer 2 Glass ball fixed layer 3 Focus layer 4 Glass ball 5 Metal reflective layer 6 Adhesive layer 7 Release material 8 Print resin layer 12 Glass ball 13 Metal reflective layer 14 Resin support sheet 15 Primer layers 16 and 18 Polyester film 17 Glass ball temporary fixing layer 19 Embossing roll 20 Cube corner type retroreflective element

Claims (18)

In a retroreflective sheet comprising a surface layer composed of at least one layer and a plurality of retroreflective elements located below the surface layer,
The retroreflective element retroreflects incident light in the direction of the light source;
At least one of the surface layers is a light coherent layer in which a color coherent color material whose color tone changes depending on the viewpoint and whose surface of the core material is covered with one or more coating layers that are substantially transparent is dispersed and added. And specularly reflects incident light in the opposite direction to the light source,
At least one layer of the retroreflective sheet is a colored layer containing a coloring material that colors retroreflected light,
The total light transmittance of the light interference layer is larger than the total light transmittance of the colored layer,
A hue variable retroreflective sheet characterized in that the retroreflected light and the specular reflected light exhibit different hues.   The hue-variable retroreflective sheet according to claim 1, wherein the hue-variable retroreflective sheet is visible under diffused light and expresses two or more hues that differ depending on the viewpoint.   The said light coherence layer is visible under the said diffused light, expresses the hue of two or more colors which change with viewpoints, and the said colored layer is located in the lower layer of the said light coherence layer. Variable hue retroreflective sheet. The hue variable retroreflective sheet according to any one of claims 1 to 3, wherein the light interference layer has a total light transmittance of 30% or more. The light interference pigment is a light interference pigment having a core material having a function of reflecting light without substantially transmitting light and a coating layer having a specular reflection function at an interface between any of the layers. hue variable retroreflective sheet according to any one of 1-4. The light coherent layer further contains the colorant in addition to the light coherent colorant, the content of the colorant is α, and the content of the light coherent colorant is β. The hue variable retroreflective sheet according to claim 5 , wherein α / β is 0.45 or less. The hue variable retroreflective sheet, diffuse visible color under light said of hue of the retroreflected light, at least one color hue according to any one of claims 1 to 6 which is achromatic Variable retroreflective sheet. The hue variable retroreflective sheet can be any of claims 1 to 7 in substantially opposite hue to the at least one color hue as the retroreflected light of a visible color under diffuse light 1 The hue variable type retroreflective sheet according to Item . The retroreflective element is a glass sphere having a refractive index of 2.10 or more, the glass sphere is enclosed in a resin, and a back surface of the glass sphere includes a focal layer, and further, a back surface of the focal layer. hue variable retroreflective sheet according to any one of claims 1 to 8, which is enclosed lens-type retroreflective sheet metal reflective layer is formed on a side. The retroreflective element is a glass sphere having a refractive index of 2.10 or more, a focal layer including the glass sphere, and a metal reflective layer is formed on the back side of the focal layer, hue variable retroreflective sheet according to any one of claims 1 to 8 disposed at random positions in the thickness direction of the focusing layer. The glass sphere includes a glass sphere group B in contact with the surface layer and a glass sphere group A located at a location away from the surface layer, and the glass sphere group A is larger than an observation angle of the glass sphere group B. The hue variable retroreflective sheet according to claim 10 , which has retroreflective performance at an observation angle. The glass sphere includes a glass sphere group B in contact with the surface layer, and a glass sphere group A located at a location away from the surface layer,
The metal reflective layer of the glass sphere group B is formed at a focal point formation position, the thickness of the focal layer of the glass sphere group A is made thinner than the thickness of the focal layer of the glass sphere group B, and compared with the glass sphere group B. The hue variable retroreflective sheet according to claim 10 , wherein the glass bulb group A has a retroreflective performance at a relatively large observation angle. The glass sphere includes a glass sphere group B that is in contact with the surface layer and a glass sphere group A that is located away from the surface layer, and a focal point formed concentrically on the glass spherical surface of the glass sphere group B. The layer has a film thickness that exhibits the highest reflection performance at an observation angle of 0.2 ° and an incident angle of 5 °, and the film thickness of the focal layer of the glass sphere group A is the film of the focal layer of the glass sphere group B. The hue variable retroreflective sheet according to claim 10 , wherein the hueable retroreflective sheet is thinner than the glass sphere group A and has a retroreflective performance at a larger observation angle than the glass sphere group B. The retroreflective element is a glass sphere having a refractive index of 1.80 or more and 2.00 or less, and a hemispherical side in which a substantially lower hemisphere of the glass sphere is covered with a metal reflecting layer is embedded in a resin support sheet. held manner, the hue variable retroreflective sheet according to any one of the glass spheres of the claims to the surface side is encapsulated lens retroreflective sheeting which air is sealed 1-8. The retroreflective element hue variable retroreflective sheet according to any one of claims 1 to 8 which is a cube corner type. The hue variable retroreflective sheet has flexibility, and there is extensible, hue variable reflexivity according to any one of claims 1 to 15 can be pasted to the 3D surface Reflective sheet. The hue variable retroreflective sheet is JISZ9117. When a 5 mm depth is pushed out by a spherical punch with a radius of 10 mm by an Erichsen film strength tester specified in JISB7729, the sheet is attached to the retroreflective sheet. The hue-variable retroreflective sheet according to claim 16 , wherein the hue-variable retroreflective sheet is free from lifting from the aluminum substrate and does not cause abnormalities such as cracks and tears. The retroreflective element is a glass sphere having a refractive index of 2.10 or more, and includes a glass sphere fixing layer, a glass sphere and a printed resin layer, a focal layer, and a metal reflective layer in this order.
The printing resin layer forms a mark,
The glass sphere is disposed in the glass sphere fixing layer,
When observed in the thickness direction of the retroreflective sheet from the surface layer direction, the position of the glass sphere and the position of the printing resin layer do not overlap,
Hue variable retroreflective sheet according to any one of claims 1-8 expressing different hue from that of the retroreflected light and the mirror-reflected light.

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