JP2007034034A - Retroreflective sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retroreflective sheet which is an encapsulated retroreflective sheet capable of being manufactured in the same manner as the conventional encapsulated retroreflective sheet, and has both of a coloring property and a retroreflective property. <P>SOLUTION: The encapsulated retroreflective sheet is composed of: at least a surface protective layer; glass spheres; a retaining layer which retains the glass spheres; a focus-forming layer; and a mirror surface reflection layer, wherein the retaining layer is colored with a colorant selected from ultraviolet ray emission colorant or light accumulation colorant. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 reflectors of infrared light reflective sensors, and more specifically, a colorant in which a holding layer for holding a glass bulb is selected from an ultraviolet light emitting colorant or a phosphorescent colorant. It is characterized by being colored with.

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 using a specular reflective layer obtained by vacuum-depositing a minute glass sphere and metal, most often aluminum, as a retroreflective element is well known. .

  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.

Thus, in an encapsulated lens type retroreflective sheet comprising at least a surface protective layer, a glass sphere, a holding layer holding the glass sphere, a focus forming layer, and a specular reflection layer, the holding layer is made of an ultraviolet light emitting colorant or a phosphorescent colorant. A retroreflective sheet is provided which is colored with a selected colorant.

  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 holding layer (3) for holding microspheres (4), and a specular reflection layer (at a focal position of the microspheres). 6) and a focus forming 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 workability, and an acrylic resin is particularly preferable in consideration of coating suitability.

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 this invention hold | maintains the microsphere shown by FIG. 1 (4), and has a holding | maintenance layer containing a ultraviolet luminescent colorant or a luminous colorant. The holding layer is usually formed by using resins such as acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, urethane resin, polycarbonate resin alone or in combination. An acrylic resin and a polyester resin are preferable from the viewpoint of weather resistance and processability, and an acrylic resin is most preferable in view of coating properties.

The colorant used in the holding layer is an ultraviolet light emitting colorant or a phosphorescent colorant. For example, a functional pigment such as an ultraviolet light emitting pigment or a phosphorescent pigment is used alone or in combination with another colorant or the like. be able to.

In the present invention, the colorant contained in the holding layer is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and further preferably 5 to 15 parts by weight of the ultraviolet light emitting colorant with respect to 100 parts by weight of the base resin. Contains parts by weight. If the addition amount of the ultraviolet light emitting colorant is not less than the lower limit value, sufficient ultraviolet light emission 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 there is no inconvenience such as becoming and the characteristics such as mechanical strength and 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 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, and 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 Zn ₂ GeO ₄ : Mn, ZnO: Zn, ZnS: Cu, ZnS: (Cu, Al), (Zn, Cd) S: (Cu, Al), ZnS: (Cu , Au, Al), Zn ₂ SiO ₄ : Mn, ZnS: (Cu, Ag), (Zn, Cd) S: Cu, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, Y ₂ SiO ₅ : (Ce, Tb), CeMgAl ₁₁ O ₁₉ : Tb, ZnS: (Cu, Co), LaOBr: (Tb, Tm), La ₂ O ₂ S: Tb, BaMg ₂ Al ₁₆ O ₂₇ (Eu, Mu), etc. Y ₂ O ₃ : Eu, Y (P, V) O ₄ : Eu, S: Eu, 0.5MgF ₂・ 3.5MgO · GeO ₂ : Mn, YVO ₄ : Eu, (Y, Gd) Red light emitting inorganic fluorescent agent such as BO ₃ : Eu; Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMg ₂ Al ₁₆ O ₂₇ : Eu, BaMgAl ₁₀ O ₁₇ : Eu, ZnS: Ag, CaWO ₄ , Y ₂ SiO ₅ : Ce, ZnS: (Ag, Ga, Cl), Sr ₂ P ₂ O ₇ : Eu, CaS: Bi, CaSrS: Bi and other blue light emitting fluorescent agents; 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.

In addition, 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, and 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 a luminous colorant include SrAl ₂ O ₄ : Eu, SrAl ₂ O ₄ : Eu, Dy, SrAl ₂ O ₄ : Eu, Nd, SrAl ₂ O ₄ : Eu, Pr, SrAl ₂ O ₄ : _{Eu, Sm, SrAl 2 O 4} : Eu, Tb, SrAl 2 O 4: Eu, Ho, SrAl 2 O 4: Eu, Mn, SrAl 2 O 4: Eu, Sn, SrAl 2 O 4: Eu, Bi, CaAl ₂ O ₄ : Eu, Nd, CaAl ₂ O ₄ : Eu, Sm, CaAl ₂ O ₄ : Eu, Tm, CaAl ₂ O ₄ : Eu, Nd, La, CaAl ₂ O ₄ : Eu, Nd, La, CaAl _{2 O 4: Eu, Nd, Ce} , CaAl 2 O 4: Eu, Nd, Pr, CaAl 2 O 4: Eu, Nd, Sm, CaAl 2 O 4: Eu, Nd, Gd, CaAl 2 O 4: Eu, Nd , Tb, CaAl ₂ O ₄ : Eu, Nd, Dy, _{CaAl 2 O 4: Eu, Nd} , Ho, CaAl 2 O 4: Eu, Nd, Er, CaAl 2 O 4: Eu, Nd, Tm, CaAl 2 O 4: Eu, Nd, Yb, CaAl 2 O 4: Eu , Nd, Lu, CaAl ₂ O ₄ : Eu, Nd, Mn, CaAl ₂ O ₄ : Eu, Nd, Sn, CaAl ₂ O ₄ : Eu, Nd, Bi, Ca _0.9 Sr _0.1 Al ₂ O ₄ : Eu, Nd , La, Ca _0.9 Sr _0.1 Al ₂ O ₄ : Eu, Nd, Dy, Ca _0.7 Sr _0.3 Al ₂ O ₄ : Eu, Nd, Dy, Ca _0.9 Sr _0.1 Al ₂ O ₄ : Eu, Nd, Ho, Ca _0.7 Sr _0.3 Al ₂ O ₄ : Eu, Nd, Ho and the like can be mentioned. 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.

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 order for the retroreflective sheet of the present invention to have sufficient light incident on the glass sphere, the distance from the interface between the surface protective layer and the holding layer to the top of the glass sphere is 15 μm or less, preferably 5 μm or less. Particularly preferably, the glass sphere is in contact with the surface protective layer.

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, in order to increase the light incident on the glass sphere, the transparency of the holding layer is improved, and the distance from the interface between the surface protective layer and the holding layer to the top of the glass sphere Is preferably smaller.

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. the resin alone or are formed using a combination, weather resistance, coatability, thermal stability acrylic resin in terms of, butyral resins are preferred.

Various additives such as a colorant, an ultraviolet absorber, a stabilizer, a plasticizer, and a cross-linking 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, butyral resin, and the like. From the viewpoint of durability, acrylic resin and butyral resin are preferable, 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, and if it is less than 10%, the coating amount becomes considerably large, which is not preferable.

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, Mw having a functional group
The use of a resin obtained by crosslinking a resin of 500,000 or more with a crosslinking agent such as an isocyanate-based crosslinking agent is most preferable because a particularly excellent holding force can be obtained.

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, but there are methods such as reverse roll coating and comma direct coating.

Next, a resin for the holding layer is applied on the surface protective layer and semi-dried. Next, a glass bulb is sprayed on the semi-dried holding layer. 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 for uniformly forming a 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 Advanced retro technology (Advantced)
Retromoden, INC) “Model 920” was used to measure the amount of retroreflective light of a 100 mm × 100 mm retroreflective sheet sample according to JISZ9117 at an observation angle of 0.2 ° and an incident angle of 5 °. The average value was used as the retroreflective 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. 100mm using UV light emitting device
× Irradiated from above the 100 mm sample so that the received light intensity on the surface of the ultraviolet light emitting region is 0.2 mW / cm2, and the luminance meter ("LS-" manufactured by Minolta Camera Co., Ltd.) from a distance of about 30 cm directly above the sample. 100 ”), the luminance of about 5 mmφ was measured and averaged at five appropriate locations on the surface of the ultraviolet light emitting region, and averaged to obtain the average ultraviolet light emitting luminance (cd / m 2) of the retroreflective sheet.

(4) Afterglow brightness of phosphorescent sheet
After a sample of 100 mm × 100 mm phosphorescent retroreflective sheet was left in the dark for 12 hours, it was irradiated for 30 minutes at a received light intensity of 1000 Lx using a D65 regular light source, then left for 10 minutes in the dark, and about 30 cm from the sample. 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 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 an acrylic resin solution (trade name, RS-3000) manufactured by Enki Aika Kogyo Co., Ltd., an isocyanate-based cross-linking agent (trade name, Sumidur N-75) manufactured by Sumitomo Bayer Urethane Co., Ltd. 12 parts by weight, 5% by weight of green ultraviolet light emitting colorant (trade name, MB-760) manufactured by Nemoto Special Chemical Co., Ltd., and 32.5 as a solvent so as to have a ratio of MIBK / toluene = 7/3. A part obtained by adding parts by weight and stirring and mixing was applied and dried at 105 ° C. for 5 minutes to form a holding layer having a thickness of 61 μm together with the surface protective layer.

A glass ball (trade name, NB-45S) manufactured by Enki Aika Kogyo Co., Ltd. was sprayed on the holding layer in an amount of 135 g / m <2> and heat-treated at 150 [deg.] C. for 3.5 minutes. At this time, the distance from the interface between the surface protective layer and the holding layer to the top of the glass bulb was 5 μm on average, and the embedding rate in the holding layer was 50 to 70%.

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
A retroreflective sheet was obtained in the same manner as in Example 1 except that the same amount by weight of a phosphorescent colorant (trade name, N nightlight) manufactured by Nemoto Special Chemical Co., Ltd. was used instead of the green ultraviolet light emitting colorant.

Example 3
A retroreflective sheet was obtained in the same manner as in Example 1 except that 10 parts by weight of the green ultraviolet light emitting colorant was used.

Example 4
A retroreflective sheet was obtained in the same manner as in Example 1 except that 2 parts by weight of the green ultraviolet light emitting colorant was used.

Example 5
A retroreflective sheet was prepared in the same manner as in Example 1 except that the same weight part of a blue ultraviolet light emitting colorant (trade name, MB-780) manufactured by Nemoto Special Chemical Co., Ltd. was used instead of the green ultraviolet light emitting colorant.

Example 6
Using the resin for forming the holding layer of Example 1, the holding layer was semi-dried at 100 ° C. for 5 minutes, and a holding layer of 63 μm was obtained together with the surface protective layer.
A glass ball (trade name, NB-56) manufactured by Enki Aika Kogyo Co., Ltd. was used as the glass bulb, sprayed on the holding layer, and heat-treated at 150 ° C. for 3 minutes and a half. At this time, all the glass balls were in contact with the surface protective layer, and the burying rate in the holding layer was 60 to 80%.

The focus forming layer was composed of two layers, a first focus forming layer and a second focus forming layer.

On the retaining layer and the glass sphere, 100 parts by weight of an acrylic resin solution (trade name, RS-4000) manufactured by Enki Aika Kogyo Co., Ltd., and a methylated melamine resin solution (trade name, Nicalac MS, manufactured by Sanwa Chemical Co., Ltd.) -11) is added to 5.5 parts by weight, 45.9 parts by weight of MIBK / toluene = 4/6 as a solvent, and stirred and mixed to form a first focus having an average thickness of 9 μm. A layer was formed.

On the first focus forming layer, 100 parts by weight of an acrylic resin solution (trade name, ST-540) manufactured by Special Color Co., Ltd., and a methylated melamine resin solution (trade name, Nicalac MS manufactured by Sanwa Chemical Co., Ltd.) -11) is added to 5.5 parts by weight, 53.1 parts by weight of MIBK / toluene = 4/6 as a solvent, and stirred and mixed to form a second focus having an average thickness of 16 μm. A layer was formed.

Subsequently, aluminum was vacuum-deposited on the second focus formation layer to form a specular reflection layer.

In the same manner as in Example 1, the pressure-sensitive adhesive layer was bonded and the carrier film was peeled off to obtain the retroreflective sheet of the present invention.

Example 7
The resin for forming the surface protective layer is 50 parts by weight of a polyester resin solution (trade name, Almatex HMP-90S) manufactured by Mitsui Chemicals, and a polyester resin solution (trade name, Almatex P-110 manufactured by Mitsui Chemicals). ) 10 parts by weight, Mitsui Chemicals Co., Ltd. polyester resin solution (trade name, Olester Q-203) 40 parts by weight, Sanwa Chemical Co., Ltd. methylated melamine resin solution (trade name, MS-11) 11 parts by weight, Mitsui Chemicals Co., Ltd. acrylic resin (trade name, Regix RL-4) 0.2 parts by weight, Toshiba silicon leveling agent (trade name, TSF4445) 0.005 parts by weight , 6 parts by weight of cellulose derivative (trade name, CAB) manufactured by Special Color Co., Ltd., UV absorber (trade name, CHINU, manufactured by Ciba Specialty Chemicals, Inc.) 213) is 0.6 parts by weight, Dainippon Ink & Chemicals Co., Ltd. catalyst (trade name, Becamine P-198) is 0.1 parts by weight, and the solvent is MIBK / toluene = 7/3. In this way, 20.7 parts by weight were added, and the mixture after stirring was applied and dried to obtain a surface protective layer having a thickness of 32 μm.

Next, 86 parts by weight of acrylic resin solution (trade name, RS-3200) manufactured by Enki Aika Kogyo 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, 55.1 parts by weight of green ultraviolet light emitting colorant (trade name, MB-760) manufactured by Nemoto Special Chemical Co., Ltd. and 35.1 parts by weight of MIBK / toluene = 7/3 as a solvent were added and mixed by stirring. The coating was dried at 105 ° C. for 5 minutes to form a holding layer having a thickness of 58 μm together with the surface protective layer.

In the same manner as in Example 1, a focus forming layer, a specular reflection layer, and an adhesive layer were formed after the dispersion of the glass spheres, and the carrier film was peeled off to obtain a retroreflective sheet of the present invention.

As a comparative example, a blue retroreflective sheet (trade name, Nikkalite EG 8106) manufactured by Nippon Carbide Industries Co., Ltd. was used. This retroreflective sheet contains a blue colorant in the surface protective layer and the holding layer, and does not contain an ultraviolet light emitting colorant.

The evaluation results are shown in Table 1.

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 3 Holding layer 4 Glass sphere 5 Focus formation layer 6 Specular reflection layer 7 Adhesive layer 8 Release base material

Claims (9)

In a sealed lens type retroreflective sheet comprising at least a surface protective layer, a glass sphere, a holding layer for holding the glass sphere, a focus forming layer, and a specular reflection layer, the holding layer is selected from an ultraviolet light emitting colorant or a phosphorescent colorant. A retroreflective sheet characterized by being colored with a colorant. The retroreflective sheet according to claim 1, wherein a distance from the interface between the surface protective layer and the holding layer to the top of the glass bulb is 15 µm or less. The retroreflective sheet according to claim 2, wherein the distance is 5 μm or less. The retroreflective sheet according to claim 2, wherein the glass bulb is in contact with the surface protective layer. The retroreflective sheet according to claim 1, wherein the total light transmittance is 70% or more when the holding layer is 15 μm. The retroreflective sheet according to claim 1, wherein the ultraviolet light emitting colorant has a central excitation wavelength of 360 nm or less. 2. The retroreflective sheet according to claim 1, 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. The retroreflective sheet according to claim 7, wherein the surface protective layer transmits 10% or less of light having a wavelength of 340 nm. The retroreflective sheet, wherein the holding layer contains an ultraviolet absorber.