JP4906063B2 - Retroreflective sheet - Google Patents

Description

  The present invention includes road signs, signs such as construction signs, license plates for vehicles such as automobiles and motorcycles, safety materials such as clothing and life preservers, markings such as signs, various authentication stickers, visible light, and laser light. Alternatively, the present invention relates to a retroreflective sheet having a novel structure that is useful in a reflector of infrared light reflective sensors, and more specifically, in a retroreflective sheet having a specular reflective layer, between the retroreflective element and the specular reflective layer. The present invention also relates to a retroreflective sheet characterized in that a destructive reflective layer comprising at least a resin component and a metal is partially provided.

Conventionally, a retroreflective sheet that reflects incident light toward a light source is well known, and the sheet using the retroreflective property is widely used in the fields of use as described above.
As such a retroreflective sheet, an encapsulated lens type retroreflective sheet is well known, which uses a microscopic glass sphere and a metal, most often aluminum, which is vacuum-deposited to provide a specular reflection layer as a retroreflective element. Yes.

  Examples of the encapsulated lens type retroreflective sheet are disclosed in detail in Japanese Patent Application Laid-Open No. 59-71848 (Patent Document 1, corresponding US Pat. No. 4,721,694) of Berisle. The above references are replaced with specific descriptions of these retroreflective sheets.

  JP-A-6-43819 (Patent Document 2) by Fujino et al. Describes an encapsulated retroreflective sheet in which a transparent fluorescent colored layer and a transparent colored layer are laminated.

Further, WO96 / 18920 (Patent Document 3, US Pat. No. 5,759,671) describes a functional retroreflective sheet in which an ultraviolet light emitting pigment layer is partially provided.

JP 59-71848 A JP-A-6-43819 WO96 / 18920 Example 3, embodiment of FIG.

The problem to be solved by the present invention is to provide a retroreflective sheet that can be produced in the same manner as a normal encapsulated retroreflective sheet, and has both coloring property and retroreflective property.

  In particular, when the holding layer is inferior in transparency, a retroreflective sheet having improved retroreflective performance by holding a part of the glass sphere in the transparent holding layer is provided.

At least the surface protective layer, the holding layer that holds the glass sphere from the light incident side , the encapsulated lens type retroreflective sheet consisting of the glass sphere, the focus forming layer, and the specular reflection layer, the holding layer is composed of two or more layers, and the light incident The problem can be solved by providing a retroreflective sheet characterized in that the holding layer on the side is transparent and at least one other holding layer is colored.

  Hereinafter, the retroreflective sheet of the present invention will be described in more detail.

FIG. 1 is a schematic cross-sectional view illustrating an encapsulated lens type retroreflective sheet.
The encapsulated lens type retroreflective sheet shown in FIG. 1 includes a surface protective layer (1), a transparent holding layer (3a) for holding microspheres (4), a colored holding layer (3b), and microspheres. It consists of a specular reflection layer (6) arranged at the focal position and a focus formation layer (5) for arranging the specular reflection layer at the focal position.

  It is also preferable to provide a printed layer (2) for transmitting information to the observer or coloring the sheet.

In the present invention, the surface protective layer (1) is a layer forming a surface layer of a retroreflective sheet having transparency with a total light transmittance of 80% or more, and is usually an acrylic resin, an alkyd resin, a fluororesin, It is formed by using resins such as vinyl chloride resin, polyester resin, urethane resin, polycarbonate resin alone or in combination. An acrylic resin, a polyester resin, and a vinyl chloride resin are preferable from the viewpoint of weather resistance and processability, and an acrylic resin is particularly preferable in consideration of coating suitability and dispersibility of a coloring agent when coloring.

Various additives such as an ultraviolet absorber, a stabilizer, a plasticizer, and a crosslinking agent can be added to the surface protective layer as long as the transparency is not significantly impaired. Further, when a transparent protective film or a transparent plate is used on the surface, the surface protective layer (1) can be omitted.

The retroreflective sheet of the present invention holds the microspheres shown in FIG. 1 (4) with a transparent holding layer (3a) and a colored holding layer (3b). Both transparent and colored retaining layers are usually formed using resins such as acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, urethane resin, polycarbonate resin alone or in combination. The Acrylic resins and polyester resins are preferred from the viewpoint of weather resistance and processability, and acrylic resins are most preferred in view of coating properties and dispersibility of the colorant.

In the present invention, the colorant contained in the surface protective layer or the holding layer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and more preferably 2 to 20 parts by weight, based on 100 parts by weight of the solid content of the base resin. Preferably it contains 5 to 15 parts by weight. If the addition amount of the colorant is not less than the lower limit value, sufficient coloring can be obtained and excellent visibility can be obtained, and if it is not more than the upper limit value, the holding layer becomes too hard and brittle. This is preferable because no inconvenience occurs and characteristics such as mechanical strength and flexibility are not impaired.

Since the excellent retroreflective performance cannot be obtained if the light transmittance of the manifestation protection layer is poor, the surface protection layer is preferably uncolored or colored with a colorant capable of obtaining transparency.

Even if the colored holding layer is colored with a colorant that can provide transparency or colored with a colorant that does not provide transparency, the head part of the glass sphere is light transmissive in any aspect. Since the glass is held by the holding layer, sufficient light is supplied to the glass sphere to obtain excellent retroreflection performance.

In the present invention, an ultraviolet light emitting encapsulated lens type retroreflective sheet or a phosphorescent encapsulated lens type retroreflective sheet is manufactured using an ultraviolet light emitting colorant or a phosphorescent colorant that has not been used in a conventional encapsulated lens type retroreflective sheet. Is preferred.

The ultraviolet light emitting colorant is not particularly limited as long as it can form an ultraviolet light emitting region that satisfies the ultraviolet light emission luminance conditions by ultraviolet light, and is generally an organic material having a relatively high light transmittance. Fluorescent agents such as naphthotriazole, benzoxazole, etc .; generally non-transparent inorganic fluorescent agents, such as inorganic metal salts, halides, sulfides, etc. Can be arbitrarily selected.

Examples of the organic fluorescent agent include diaminostilbenzene, uranin, thioflavin T, eosin, rhodamine B, acridine orange, diphenylmethane, triphenylmethane, xanthene, thiazine, and thiazole dyes as a base. An organic pigment etc. are mentioned. These can be used as one kind or a mixture of two or more kinds.

Examples of the inorganic fluorescent agent include Zn2GeO4: Mn, ZnO: Zn, ZnS: Cu, ZnS: (Cu, Al), (Zn, Cd) S: (Cu, Al), ZnS: (Cu, Au, Al), Zn2SiO4: Mn, ZnS: (Cu, Ag), (Zn, Cd) S: Cu, Gd2O2S: Tb, La2O2S: Tb, Y2SiO5: (Ce, Tb), CeMgAl11O19: Tb, ZnS: (Cu, Co ), LaOBr: (Tb, Tm), La2O2S: Tb, BaMg2Al16O27 (Eu, Mu), etc., green emitting inorganic fluorescent agents; Y2O3: Eu, Y (P, V) O4: Eu, S: Eu, 0.5MgF2, 3.5MgO · GeO2: Mn, YVO4: Eu, (Y, Gd) BO3: Eu and other red light-emitting inorganic fluorescent agents; And blue light emitting fluorescent agents such as Y2SiO5: Ce, ZnS: (Ag, Ga, Cl), Sr2P2O7: Eu, CaS: Bi, and CaSrS: Bi. These can be used as one kind or a mixture of two or more kinds. Moreover, you may use combining these inorganic type fluorescent agents and the said organic fluorescent agent.

Inorganic fluorescent agents are generally superior in light resistance, heat resistance, solvent resistance, etc. compared to organic fluorescent agents, so depending on the environment in which the UV light emitting retroreflective sheet is used, inorganic fluorescent agents Is preferably used. Among the inorganic fluorescent agents, the above-mentioned green light-emitting inorganic fluorescent agent, red light-emitting inorganic fluorescent agent, and the like, which are particularly bright at the time of UV emission and give excellent visibility for night viewers, Use of a blue light emitting inorganic fluorescent agent is preferred.

Further, among inorganic fluorescent agents, those having a particle size distribution containing 80% by weight or more of particles having a particle size of 25 μm or less are preferable. In the case of a green light emitting inorganic fluorescent agent, the width of the particle size distribution is 0.1 to 50 μm and the maximum frequency The particle size is about 12 μm, the red light emitting inorganic fluorescent agent has a particle size distribution width of 0.1 to 8 μm and the maximum frequency particle size is about 3 μm, and the blue light emitting inorganic fluorescent agent has a particle size distribution width of Those having a maximum frequency particle size of 8 μm and 0.1 to 12 μm can be suitably used.
Furthermore, as these inorganic fluorescent agents, it is generally preferable to use those that emit light by UV irradiation within a wavelength range of 250 to 400 nm.

In the present invention, the phosphorescent colorant used refers to a colorant having persistence for 10 minutes or more after quenching.

In the present invention, the holding layer preferably contains 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and still more preferably 5 to 15 parts by weight of the phosphorescent colorant with respect to 100 parts by weight of the solid content of the base resin. May be. If the amount of phosphorescent colorant added is not less than the lower limit, a sufficient phosphorescent light emitting function can be obtained, and excellent distinguishability and visibility can be obtained, and if it is not more than the upper limit, the holding layer becomes hard. This is preferable because it does not cause inconvenience and the properties such as flexibility are not impaired. Moreover, it is preferable because the total light transmittance of the holding layer does not become too low and the brightness of the retroreflective sheet does not become too low.

The phosphorescent colorant is not particularly limited as long as it accumulates light such as daytime sunlight or nighttime fluorescent light and emits light even in the dark and has light emission performance necessary for product identification. However, from the viewpoint of good phosphorescent performance, an oxide-based phosphorescent coloring agent, particularly a metal oxide represented by the general formula MAl2O4 (wherein M represents at least one alkaline earth metal) is used as a mother crystal and activated. A luminous colorant containing a rare earth metal atom in a ratio of 1 × 10 −6 to 0.2 (provided that the total number of metal M atoms and rare earth metal atoms is 1) is preferred.

The alkaline earth metal is preferably at least one metal selected from the group consisting of Ca, Ba and Sr. The rare earth metal is Sc, Y, La, Ce, Pr, Nd, Sm, It may be at least one metal selected from the group consisting of Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Such phosphorescent colorant further contains at least one metal selected from the group consisting of Mn, Sn and Bi as a co-activator at a ratio of 1 × 10 −6 to 0.2 (provided that metal M atom It is preferable that the phosphorescent colorant contains a rare earth metal atom and a coactivator metal having a total atom number of 1).

Examples of such luminous colorants include SrAl2O4: Eu, SrAl2O4: Eu, Dy, SrAl2O4: Eu, Nd, SrAl2O4: Eu, Pr, SrAl2O4: Eu, Sm, SrAl2O4: Eu, Tb, SrAl2O4: Eu, H, O SrAl2O4: Eu, Mn, SrAl2O4: Eu, Sn, SrAl2O4: Eu, Bi, CaAl2O4: Eu, Nd, CaAl2O4: Eu, Sm, CaAl2O4: Eu, Tm, CaAl2O4: Eu, Nd, La, CaAl2Od: E , La, CaAl2O4: Eu, Nd, Ce, CaAl2O4: Eu, Nd, Pr, CaAl2O4: Eu, Nd, Sm, CaAl2O4: Eu, Nd, Gd, CaAl2O4: Eu, Nd, Tb, CaAl2O4: Eu, Nd, Dy CaAl2O4: Eu, Nd, Ho, CaAl2O4: Eu, Nd Er, CaAl2O4: Eu, Nd, Tm, CaAl2O4: Eu, Nd, Yb, CaAl2O4: Eu, Nd, Lu, CaAl2O4: Eu, Nd, Mn, CaAl2O4: Eu, Nd, Sn, CaAl2O4: Eu, Nd, Bi, Ca0.9Sr0.1Al2O4: Eu, Nd, La, Ca0.9Sr0.1Al2O4: Eu, Nd, Dy, Ca0.7Sr0.3Al2O4: Eu, Nd, Dy, Ca0.9Sr0.1Al2O4: Eu, Nd, Ho, Ca0. 7Sr0.3Al2O4: Eu, Nd, Ho and the like. These may be used alone or as a mixture of two or more.

The afterglow characteristics of these phosphorescent colorants are not particularly limited, but in view of visibility, those having a brightness of 150 mcd / m 2 or more, preferably 200 mcd / m 2 or more, more preferably 250 mcd / m 2 or more are generally used. It is good.

In addition to the colorant, various additives such as an ultraviolet absorber, a stabilizer, a plasticizer, and a crosslinking agent can be added to the holding layer as long as the physical properties are not impaired.

Also, if necessary, curing agents such as alkylated amino resins, alkylated urea resins, isocyanate-based crosslinking agents; release agents such as silicon-based release agents and cellulose-based release agents; polyester-modified polydimethylsiloxane, silicon-based surfactants , May contain additives such as surface modifiers such as acrylic polymers

The molecular weight of the resin forming the holding layer is not particularly limited, but the resin has a weight average molecular weight (hereinafter sometimes abbreviated as Mw) of 50,000 or more, more preferably 50,000 to 400,000. Resin, more preferably 100,000 to 300,000 resin is used. When a resin that is within this range and reacted with an appropriate curing agent is used, beads can be appropriately submerged in the resin.

The holding layer can be applied several times as necessary, and different types of resins may be laminated.

In the present invention, the holding layer is at least two layers of a transparent holding layer and a colored holding layer. As a manufacturing method, a transparent holding layer is laminated on the surface protective layer and semi-dried, and a colored holding layer is laminated thereon and semi-dried, a glass bulb is applied, and the glass bulb is embedded in the holding layer. It is. At this time, if the transparent holding layer is insufficiently dried, it is difficult to apply the colored holding layer, and if the transparent holding layer is too dry, the glass bulb does not reach the transparent holding layer.

In order to prevent the drying of the transparent holding layer from progressing excessively, for example, the transparent holding layer is semi-dried at a lower temperature compared to the semi-drying of the colored holding layer, or the resin used for the colored holding layer. Glass ball coating by reducing the weight average molecular weight of the resin used for the transparent holding layer or reducing the amount of the crosslinking agent used for the transparent holding layer compared to the amount of the crosslinking agent used for the colored holding layer Sometimes it is preferred that a transparent holding layer can hold the glass bulb.

The resin solid content of the resin for the holding layer is 25 to 50%, preferably 30 to 40%, more preferably 33 to 38%, and the resin coating thickness of the holding layer is 15 μm to 50 μm. When several layers are laminated, the coating thickness of the holding layer for holding the glass sphere is determined according to conditions such as the glass sphere diameter.

The resin solid content of the resin for the holding layer is 25 to 50%, preferably 30 to 40%, more preferably 33 to 38%, and the resin coating thickness of the holding layer is 15 μm to 50 μm. When several layers are stacked, the coating thickness of the holding layer that holds the microspheres is determined in accordance with conditions such as the microsphere diameter.

The retroreflective sheet of the present invention is preferably formed using a glass bead lens or the like having a function of retroreflecting light in cooperation with the specular reflection layer located at the focal position. The refractive index of the glass beads is 2.0 to 2.5, preferably 2.0 to 2.3.

The size of the microsphere used as the retroreflective element is usually about 10 μm to 150 μm, but in order to increase the reflectivity to the front, it is preferable to use a larger diameter, preferably Are those having an average diameter of about 25 μm to 120 μm, more preferably about 40 μm to 90 μm.

In the retroreflective sheet of the present invention, the top of the glass sphere is held by a transparent holding layer, and as the transparency, the total light transmittance is preferably 50% or more. / 15 or more is preferably held by a transparent holding layer in order to supply sufficient light to the glass sphere.

In the retroreflective sheet of the present invention, if the diameter of the glass sphere is large, higher reflection performance can be obtained. Therefore, even if the light incident on the glass sphere is slightly less, sufficient reflection performance can be obtained. When the diameter of the glass sphere is small, it is preferable to increase the portion held by the transparent holding layer in order to increase the light incident on the glass sphere.

As the ultraviolet light emitting colorant used in the present invention, those having a central excitation wavelength of 360 nm or less are preferable because sufficient color can be obtained with black light or the like.

In the present invention, the retroreflective sheet preferably contains an ultraviolet absorber in the surface protective layer or the holding layer in order to improve the weather resistance.

In the present invention, it is preferable that 50% or more of the wavelength of 360 nm is transmitted so that the coloring of the holding layer of the retroreflective sheet is sufficiently visible, and light having a wavelength of 340 nm is used in order to improve the weather resistance of the retroreflective sheet. It is preferable that it is 10% or less.

Examples of such ultraviolet absorbers include salicylate-based ultraviolet absorbers such as pt-butylphenyl salicylate, titanium dioxide, and the like.

Such an ultraviolet absorber has an ultraviolet absorption wavelength end of 360 nm or less and does not hinder the color development of the excitation coloring layer, so that the thickness and amount of the ultraviolet absorbing layer can be determined in consideration of weather resistance. .

In addition, by adjusting the number of additions of ultraviolet absorbers other than those described above, the ultraviolet absorption at a wavelength of 360 nm is 75% or less, preferably 50% or less, and light having a wavelength of 340 nm is transmitted through 10% or less. Can be adjusted.

Examples of such an ultraviolet absorber include benzotriazole-based ultraviolet absorbers such as 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- Benzophenone ultraviolet absorbers such as hydroxy-4h-dodecylbenzophenone, cyanoacrylate ultraviolet absorbers such as 2-ethylhexyl-2-cyano-3,3-diphenylcyanoacrylate, 2, (4,6-diphenyl-1,3 , 5-triazin-2-yl) -5 [(hexyl) oxy] -phenol and other triazine-based ultraviolet absorbers, zinc oxide, etc., and good weather resistance is obtained without impeding the coloring of the excitation coloring layer. As can be seen, the thickness and amount of the ultraviolet absorbing layer can be determined.

The retroreflective sheet of the present invention further has a focus forming layer shown in FIG. The focus forming layer is a layer for disposing the specular reflection layer at the focal position of the microsphere, and is usually acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, urethane resin, polycarbonate resin, butyral resin, etc. These resins are used alone or in combination, but acrylic resins and butyral resins are preferred from the viewpoint of weather resistance, coating suitability, and thermal stability.

Various additives such as a colorant, an ultraviolet absorber, a stabilizer, a plasticizer, and a crosslinking agent can be added to the focus forming layer as long as the transparency is not significantly impaired.
The resin forming the focal resin layer is not particularly limited, and examples thereof include acrylic resin, urethane resin, and butyral resin. Acrylic resin and butyral resin are preferable from the viewpoint of durability, and acrylic resin is most preferable in view of coating properties.

The molecular weight of the resin forming the focus forming layer is not particularly limited, but the resin has a Mw of 100,000 or more, more preferably 100,000 to 400,000, and further preferably 150,000 to 300,000. It is preferable to use a resin. When a resin within this range and reacted with an appropriate curing agent is used, a spherical focus forming layer can be formed.

The viscosity at the time of application of the resin forming the focus forming layer is 10 to 600 cP, preferably 30 to 600 cP, more preferably 50 to 200 cP, and the resin solid content of the focus forming layer resin is 10 to 40%, Preferably it is 15 to 35%, more preferably 15 to 25%. If the resin solid content is large, it is easy to entrain air bubbles and foam easily.

The thickness of the focus forming layer is determined in consideration of the refractive index of the resin so that the incident light beam is focused on the specular reflection layer, but is usually 10 μm to 60 μm, preferably 15 μm to 50 μm, particularly preferably 20 μm. ~ 40 μm.

The retroreflective sheet of the present invention also has a specular reflection layer shown in FIG. The specular reflection layer is a layer for reflecting light, and is usually formed by means such as vacuum deposition or sputtering using a metal such as aluminum or silver, but a metal thin film reflecting the shape of the base is used. In order to form uniformly, a vapor deposition method is particularly preferable. The thickness of the metal layer is 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, particularly preferably 0.05 to 0.1 μm.

The chromogenic retroreflective sheet of the present invention has an adhesive layer for adhering the sheet to a substrate, if necessary. The type of resin forming the adhesive layer is not particularly limited, and a resin used as a normal adhesive resin may be used. For example, acrylic resin, silicon resin, rubber resin, phenolic resin Resin or the like is used. Among them, an acrylic resin or a silicon resin having excellent weather resistance and good adhesive properties is preferably used.

The molecular weight of the resin forming the adhesive layer is not particularly limited, but a resin having a higher molecular weight tends to obtain a suitable holding force, and has a weight average molecular weight (hereinafter sometimes abbreviated as Mw) 50. It is suitable to use 10,000 or more resins, more preferably 500,000 to 1,000,000 resins, and still more preferably 600,000 to 1,000,000 resins. Among them, it is most preferable to use a resin obtained by crosslinking a functional group-containing resin having an Mw of 500,000 or more with a crosslinking agent such as an isocyanate-based crosslinking agent.

The retroreflective sheet of the present invention is manufactured by the method described below. First,
The resin for the process substrate surface protective layer is applied and dried. The process base material is not particularly limited as long as it has sufficient strength and expands and contracts sufficiently when heated, but a base material such as polyethylene terephthalate (PET), polyimide, or vinyl chloride is used. It is possible and PET is particularly preferred.

The coating method is not particularly limited as long as it can be uniformly applied with a predetermined thickness, and there are methods such as reverse roll coating and comma direct coating.

Next, a resin for the holding layer on the light incident side is applied on the surface protective layer and semi-dried. Next, the resin for the holding layer on the focus forming layer side is coated and semi-dried on the semi-dried holding layer on the light incident side. A glass bulb is sprayed on the semi-dried holding layer on the focus forming layer side. With this semi-drying degree, the embedding rate for embedding the glass spheres in the retaining layer can be adjusted. For example, when acrylic is used as the resin, 50 ° C. to 150 ° C., preferably 70 ° C. to 130 ° C., especially Preferably, it is dried at 80 ° C. to 120 ° C. for about 5 minutes to facilitate embedding the glass bulb.

Further, the glass bulb is embedded in the holding layer by the surface tension of the holding layer by performing a heat treatment at about 150 ° C.

The embedding rate of the glass spheres in the holding layer is not particularly limited and varies depending on the type of the holding layer resin. For example, when acrylic is used as the resin, 20% from the point of holding the glass spheres. The above is good.

Next, the focus forming layer resin is applied to the surface of the glass beads. The coating method is not particularly limited as long as it can be uniformly applied with a predetermined thickness, and there are methods such as reverse roll coating and comma direct coating.

Apply at room temperature and heat-treat as necessary to cure the resin. The curing temperature varies depending on the type of the resin / curing agent, but when an acrylic resin is used as the focus forming layer resin, it is preferably heated to 50 ° C. to 160 ° C., preferably 70 ° C. to 155 ° C. Moreover, you may apply | coat a focus formation layer in several times as needed.

Next, a metal thin film is formed on the focus formation layer. As a method for forming the metal thin film, a coating method, a vapor deposition method, or the like can be used. However, the vapor deposition method is particularly preferable in order to uniformly form the metal thin film reflecting the shape of the base. The thickness of the metal layer is 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, particularly preferably 0.05 to 0.1 μm.

Conditions such as the deposition rate, temperature and degree of vacuum may be selected according to the equipment, but it is preferable to select the rate, temperature and degree of vacuum so that the metal thin film has a uniform thickness. .

In the case of an embodiment having an adhesive layer, the adhesive layer is then applied onto the release film and bonded to the intermediate product after metal deposition on the adhesive layer surface. The bonding conditions vary depending on the adhesive, but when an acrylic resin is used as the adhesive, it is preferable to apply pressure while applying a certain amount of heat.

Finally, if the process substrate is peeled off, the retroreflective sheet of the present invention can be obtained. The peeling angle, peeling speed, etc. are not particularly limited, but peeling is carried out by appropriately adjusting the angle and speed so as not to break the sheet.

The reflectivity of the retroreflective sheet of the present invention is determined as desired in consideration of the balance with the color developing property, but in order to sufficiently function as a retroreflective sheet, the front reflection performance (incident angle 0.2 °) , Retroreflective performance at an observation angle of 5 °) is 20 cd / lx. m2 or more, preferably 30 cd / lx. m2 or more, more preferably 40 cd / lx. It should be m2 or more.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, the measuring method used in the Example and the comparative example is as follows.

(1) Saturation Using a Nippon Denshoku color difference meter (Model SE-2000), the hue of the retroreflective sheet was measured according to JISZ9117, and the intensity of color development was determined from the Y value.

(2) Front retroreflective performance Using “Model 920” manufactured by Advanced Retro Technology (INC) as a retroreflective performance measuring instrument, the retroreflective light quantity of a 100 mm x 100 mm retroreflective sheet sample conforms to JISZ9117. Then, measurement was made at five appropriate points with an observation angle of 0.2 ° and an incident angle of 5 °, and the average value was used as the retroreflection performance value.

(3) Ultraviolet light emitting sheet with 4 UV light emitting fluorescent lamps with UV light emission brightness of 10W, with a cut filter on the front, emits near ultraviolet light with a main wavelength of around 360nm and a wavelength range of 300 ~ 420nm. Using an ultraviolet light emitting device, irradiate from above the 100 mm x 100 mm sample so that the received light intensity at the surface of the ultraviolet light emitting region is 0.2 mW / cm2, and from a distance of about 30 cm directly above the sample, a luminance meter (Minolta camera) Using “LS-100” manufactured by Co., Ltd.), the average brightness of the retroreflective sheet (cd / m 2) was measured by measuring the brightness of about 5 mmφ at five appropriate locations on the surface of the UV light emitting area. It was.

(4) Afterglow brightness of phosphorescent sheet
A sample of a 100 mm × 100 mm phosphorescent retroreflective sheet was allowed to stand for 12 hours in the dark, then irradiated using a D65 regular light source at a received light intensity of 1000 Lx for 30 minutes, and then left for 10 minutes in the dark. Using a luminance meter (“LS-100” manufactured by Minolta Camera Co., Ltd.) from the distance, measure and average the residual light intensity of about 5 mmφ for the appropriate 5 points on the surface of the phosphorescent light emitting area, and average the afterglow of the retroreflective sheet. The brightness (mcd / m2) was used.

(5) Decorative properties The retroreflective sheet obtained is irradiated with black light, and 50 monitors of 18 to 60 years old visually determine whether it feels that the decorative properties have improved compared to the state without irradiation. did.
(In the case of a phosphorescent sheet, the state where the phosphorescent light is emitted is compared with the state where the light emission is completed)
Judgment criteria:
0 points: No decorativeness 1 point: Depends on the application, but generally no decorativeness 2 points: Good decorativeness 3 points: Excellent decorativeness judgment result:
×: 30 points or less (no decoration)
Δ: 30 points or more and less than 90 (no decorativeness depending on the person observing)
○: 90 or more and less than 120 (good decoration)
A: 120 or more (excellent decorativeness)

(6) Appearance The appearance of the obtained retroreflective sheet was visually determined.
×: Opaque colorant is not uniformly dispersed, and appearance is uneven Δ: The whole is dull and discolored ○: Appearance unevenness is partially observed when observed carefully ◎: Normal recursion The appearance that is not inferior to the reflective sheet

Example 1
A 75 μm thick transparent polyethylene terephthalate film (trade name, Teijin Tetron Film S-75) manufactured by Teijin Ltd. was used as the carrier film, and an acrylic resin solution (trade name, RS-- 1200 parts by weight, methylated melamine resin solution manufactured by Sanwa Chemical Co., Ltd. (trade name, Nicalac MS-11) and 14 parts by weight cellulose derivative (trade name, CAB) by Special Colorant Co., Ltd. In part, 0.5 parts by weight of UV absorber made by Sipro Kasei Co., Ltd. (trade name, Seasoap 103) and 0.04 parts by weight of leveling agent (trade name, BYK-300) made by Big Chemie Japan Co., Ltd. In addition, 0.12 parts by weight of a catalyst (trade name, Beccamin P-198) manufactured by Dainippon Ink & Chemicals, Inc. as a solvent and MIBK / TO A surface protective layer having a thickness of 36 μm was formed by adding 16.7 parts by weight so that the ratio of ruene = 8/2, and stirring and mixing.

On the surface protective layer, 100 parts by weight of acrylic resin (trade name RS-3000) manufactured by Onuki Ai Co., Ltd. and 12 parts by weight of isocyanate-based crosslinking agent (trade name, Sumidur N-75) manufactured by Sumitomo Bayer Urethane Co., Ltd. In addition, 21 parts by weight of toluene as a solvent and 9 parts by weight of MIBK were mixed and stirred on the surface protective layer, dried at 80 ° C. for 5 minutes, 10 μm thick and 95% transmittance on the light incident side. A retention layer was obtained.
Next, 100 parts by weight of RS-3000, 22 parts by weight of a blue colorant (trade name AR-6300) manufactured by Special Colorant Industries Co., Ltd., 13.6 parts by weight of Sumidur N-75 and 20 parts by weight of toluene Then, 10 parts by weight of MIBK mixed and stirred was applied on the light incident side holding layer and dried at 100 ° C. for 5 minutes to obtain a focus forming layer side holding layer having a thickness of 13 μm and a transmittance of 10%. .

A glass sphere (trade name, NB-45S) manufactured by Aki Ai Co., Ltd. was attached to the holding layer on the focus forming layer side, and heat-treated at 145 ° C. for 3 minutes and 30 seconds, so that the glass sphere was submerged in the holding layer.
When the cross section was observed with a microscope, the head of the glass beads was in contact with the surface protective layer, and approximately 1/5 of the diameter of the glass sphere was held in the holding layer on the light incident side.
In addition, the thickness and transmittance of each holding layer were separately applied to a Teijin Limited polyester film (trade name, Teijin Tetron Film S-75) having a thickness of 75 μm and a transmittance of 93%. Was determined by subtracting 75 from the total thickness, and the transmittance was determined by measuring the transmittance in the state of being laminated on the polyester film and dividing by 0.93.

Next, on the retaining layer and the glass bulb, 100 parts by weight of an acrylic resin solution (trade name, RS-5000) manufactured by Unki Aika Co., Ltd., a methylated melamine resin solution (trade name, manufactured by Sanwa Chemical Co., Ltd.) Nicarak MS-11) was added to 5.5 parts by weight, 39.3 parts by weight of MIBK / toluene = 4/6 as a solvent, and stirred and mixed to form a focus having an average thickness of 23 μm. A layer was formed.

Subsequently, aluminum was vacuum-deposited on the focus forming layer to obtain a specular reflection layer.

Moreover, as a release paper, a release paper (trade name, E2P-H (P)) manufactured by Lintec Corporation is used, and an ethyl acetate of a BA / AA copolymer (weight ratio: BA / AA = 90/10) is provided thereon. / Toluene (1/1) solution (solid content 34%) 100 parts by weight, white colorant (trade name, AR-9127W) manufactured by Special Colorant Co., Ltd., 9 parts by weight, isocyanate system manufactured by Nippon Polyurethane Industry Co., Ltd. A cross-linking agent (trade name, Coronate L) is added to 0.5 parts by weight, and 16.1 parts by weight of ethyl acetate as a solvent is added, followed by stirring and mixing to form a pressure-sensitive adhesive layer having a thickness of 41 μm. did.

After laminating the specular reflection layer and the pressure-sensitive adhesive layer, the carrier film was peeled off to obtain the retroreflective sheet of the present invention.

Example 2
In Example 1, a retroreflective sheet was obtained in the same manner as in Example 1 except that the thickness of the light incident side holding layer was 12 μm. The transmittance of the holding layer on the light incident side was 94%. The head of the glass sphere is not in contact with the surface protective layer, and the ratio of the glass sphere held by the holding layer on the light incident side and the ratio held by the focus forming layer are the same as in Example 1. It was.

Example 3
In Example 2, a retroreflective sheet was obtained in the same manner as in Example 2 except that the drying temperature of the holding layer on the light incident side was 70 ° C. and the drying temperature of the holding layer on the focus forming layer side was 90 ° C. The head of the glass sphere was in contact with the surface protective layer, and about 1/4 of the diameter of the glass sphere was held in the holding layer on the light incident side. The focal layer was formed so that the average thickness was 21 μm.

Example 4
In Example 3, so that the thickness of the entire holding layer and the hue of the retroreflective sheet are the same as those in Example 1, the holding layer on the focus forming layer side was AR-6300 in 23 parts by weight, and Sumijoule N-75. Was changed to 13.8 parts by weight and mixed and stirred to obtain a holding layer on the focus forming layer side having a thickness of 12 μm and a transmittance of 9%. The average thickness of the focus forming layer was formed to be 23 μm.

Example 5
The light incident side holding layer is light blue, the focus forming layer side holding layer is dark blue, and the light incident side holding layer is RS-3000 so that the hue as the retroreflective sheet is the same as in Example 1. 100 parts by weight, 2 parts by weight of AR-6300, 13.3 parts by weight of Sumidur N-75, 21 parts by weight of toluene and 9 parts by weight of MIBK were mixed and stirred at 105 ° C. for 5 minutes, A holding layer on the light incident side having a thickness of 10 μm and a transmittance of 80% was obtained. The holding layer on the focus forming layer side is mixed with 100 parts by weight of RS-3000, 20 parts by weight of AR-6300, 13.5 parts by weight of Sumidur N-75, 21 parts by weight of toluene, and 9 parts by weight of MIBK. What was stirred was dried at 100 ° C. for 5 minutes, and a retroreflective sheet was obtained in the same manner as in Example 1 except that a holding layer on the focus forming layer side having a thickness of 13 μm and a transmittance of 15% was obtained.

Example 6
In Example 1, the holding layer on the focus forming layer side is 100 parts by weight of RS-3000, the green ultraviolet light emitting colorant (trade name, MB-760) manufactured by Nemoto Special Chemical Co., Ltd. is 5 parts by weight, A mixture of 12 parts by weight of N-75, 22 parts by weight of toluene and 10 parts by weight of MIBK mixed and stirred was dried at 105 ° C. for 5 minutes to obtain a holding layer on the focus forming layer side having a thickness of 12 μm and a transmittance of 2%. Except for this, a retroreflective sheet was obtained in the same manner as in Example 1.

Example 7
In Example 6, the retention layer on the focus forming layer side was RS-3000 in 100 parts by weight, Sipro Kasei Co., Ltd. UV absorber (trade name, Seasoap 103) in 0.5 parts by weight, Nemoto Special Chemical Co., Ltd. ) Made by mixing 5 parts by weight of green ultraviolet light emitting colorant (trade name, MB-760), 12 parts by weight of Sumidur N-75, 22 parts by weight of toluene and 10 parts by weight of MIBK at 105 ° C. A retroreflective sheet was obtained in the same manner as in Example 6 except that the film was dried for 5 minutes to obtain a holding layer on the focus forming layer side having a thickness of 12 μm and a transmittance of 2%.

Example 8
A retroreflective sheet was obtained in the same manner as in Example 6 except that the same weight part of a storage colorant (trade name, N nightlight) manufactured by Nemoto Special Chemical Co., Ltd. was used instead of the ultraviolet light emitting colorant in Example 6.

Comparative Example 1
A retroreflective sheet was obtained in the same manner as in Example 1 except that the drying condition of the holding layer on the light incident side was changed to 110 ° C. for 5 minutes.

Table 1 shows the properties, appearance and decorative properties of the obtained retroreflective sheet.

It is sectional drawing of the enclosure lens type retroreflection sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface protective layer 2 Printing layer 3a, 3b Holding layer 4 Glass sphere 5 Focus formation layer 6 Specular reflection layer 7 Adhesive layer 8 Peeling base material 9 Incident direction of light

Claims (7)

At least the surface protective layer, the holding layer that holds the glass sphere from the light incident side, the encapsulated lens type retroreflective sheet consisting of the glass sphere, the focus forming layer, and the specular reflection layer, the holding layer is composed of two or more layers, and the light incident A retroreflective sheet characterized in that the holding layer on the side is transparent, at least one other holding layer is colored , and the transparent holding layer holds 1/15 or more of the diameter of the glass bulb . The retroreflective sheet according to claim 1, wherein the colored holding layer is colored with an ultraviolet light emitting colorant or a phosphorescent colorant. 3. The retroreflective sheet according to claim 1, wherein the total light transmittance of the colored holding layer is 70% or less. The retroreflective sheet according to claim 2, wherein the ultraviolet excitation colorant has a central excitation wavelength of 360 nm or less. The retroreflective sheet according to any one of claims 1 to 4 , wherein the surface protective layer contains an ultraviolet absorber, and the surface protective layer transmits 50% or more of light having a wavelength of 360 nm. 6. The retroreflective sheet according to claim 5, wherein the surface protective layer transmits 10% or less of light having a wavelength of 340 nm. The retroreflective sheet according to any one of claims 1 to 6 , wherein the holding layer contains an ultraviolet absorber.