JP4817989B2 - 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. Or a retroreflective sheet having a novel structure useful for reflectors of infrared light reflective sensors

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. Sho 59-71848 (Patent Document 1, corresponding US Pat. No. 4,721,649) of Berisle. The above references are replaced with specific descriptions of these retroreflective sheets.

  Further, the inventors of the present invention provide an encapsulated lens type retroreflective sheet comprising at least a surface protective layer, a holding layer for holding a glass sphere, a glass sphere, a focus forming layer, and a specular reflection layer. Thus, an application has been filed for a retroreflective sheet, wherein the light incident side holding layer is transparent and at least one other holding layer is colored. (Patent Document 2)

Further, the inventors of the present invention provide an encapsulated lens type retroreflective sheet comprising at least a surface protective layer, a holding layer for holding a glass sphere, a glass sphere, a focus forming layer, and a specular reflection layer. Thus, an application has been filed for a retroreflective sheet, wherein the light-incident-side holding layer is transparent, and at least one other holding layer is colored white or yellow. (Patent Document 3)

However, the above-mentioned three publications have no description or suggestion that 70% or more of the total amount of the colorant contained in the surface protective layer and the holding layer of the retroreflective sheet is contained in the holding layer.

JP 59-071848 A Japanese Patent Application No. 2006-078370 Japanese Patent Application No. 2006-135147

The problem to be solved by the present invention is to solve the disadvantage that the dark retroreflective sheet has low luminance and the light retroreflective sheet has poor weather resistance.

The retroreflective sheet of the present invention is an encapsulated retroreflective sheet that can be produced in the same manner as a normal encapsulated retroreflective sheet. In the dark retroreflective sheet, the coloring concentration of the surface protective layer is increased by increasing the coloring concentration of the holding layer. , The transparency of the surface protective layer can be increased to provide a retroreflective sheet with high brightness, and in the light-colored retroreflective sheet, the surface protective layer is made almost colorless and transparent, and is colored with a holding layer. The luminance increases as well as the dark color, and it is possible to increase the weather resistance of the colorant and to provide a retroreflective sheet having high brightness and good weather resistance.

In an encapsulated lens type retroreflective sheet composed of at least a surface protective layer and one or more holding layers for holding a glass sphere, a glass sphere, a focus forming layer, and a specular reflection layer, the holding layer has two or more layers, and light incident Provided is a retroreflective sheet characterized in that the holding layer on the side is transparent, and the surface protective layer of the retroreflective sheet and 70% or more of the total amount of colorant contained in the retentive layer are contained in the retentive layer By doing so, the problem can be solved.

  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 (3) for holding the glass sphere (4), and a specular reflection layer arranged at the focal position of the microsphere. (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 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.

In the retroreflective sheet of the present invention, the glass sphere shown in FIG. 1 (4) is held by the holding layer (3). 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. 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.

In the present invention, the retroreflective sheet having a dark color means that the Y value of the retroreflective sheet is smaller than 17, and the light color means that the Y value of the retroreflective sheet is 17 or more. Say.

In the present invention, when the retroreflective sheet is a dark color such as red, green, blue, and black, for example, the color density of the holding layer is increased, and the color density of the surface protective layer is decreased accordingly. It is preferable to increase the luminance. In the present invention, if 50% or more and further 70% or more of the total amount of the colorant contained in the surface protective layer and the holding layer is contained in the holding layer, the coloring density of the surface protective layer is lowered, and the retroreflection of high luminance is performed. Since a sheet is obtained, it is preferable.

In the present invention, for example, when the retroreflective sheet is a light color such as yellow, lemon yellow, orange, or pink, the surface protective layer is a color that is nearly colorless and transparent, and the color density of the holding layer is increased. It is preferable to increase weather resistance. In the present invention, if 60% or more and further 80% or more of the total amount of the colorant contained in the surface protective layer and the holding layer is contained in the holding layer, the amount of UV light reaching the colorant contained in the holding layer can be reduced. For this reason, it is preferable since the weather resistance of the colorant is improved.

In the present invention, since the coloring density of the holding layer becomes high, if the 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, further 5 μm or less, the light incident on the glass bulb Is not too small, and preferable brightness is obtained as a retroreflective sheet.

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

The size of the glass sphere 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.

The retroreflective sheet of the present invention further has a focus forming layer shown in FIG. The focal point forming layer is a layer for disposing the specular reflection layer at the focal position of the glass sphere. 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 retroreflective sheet of this invention has an adhesive bond layer for adhere | attaching this sheet | seat on a base material as needed. 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.

FIG. 2 is a schematic cross-sectional view illustrating an encapsulated lens type retroreflective sheet.
The encapsulated lens type retroreflective sheet shown in FIG. 2 includes a surface protective layer (1), a transparent holding layer (3a) holding a glass bulb (4), a colored holding layer (3b), and a glass bulb 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 glass sphere shown in FIG. 2 (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.

The colored holding layer may be colored with a colorant that provides transparency, or may be colored with a colorant that does not provide transparency. Since this is held by the holding layer, sufficient light is supplied to the glass bulb to obtain excellent retroreflection performance.

In the present invention, when there are two or more retaining layers, it is preferable that the two or more retaining layers contain a total of 70% or more of the colorant.

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 transparent holding layer and the colored 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, whether it is a transparent holding layer or a colored holding layer, is not particularly limited, but the weight average molecular weight (hereinafter sometimes abbreviated as Mw) of the resin is 50,000 or more. It is preferable to use a resin, more preferably from 50,000 to 400,000, and even more preferably from 100,000 to 300,000. 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 in several steps as necessary, and a transparent holding layer and a colored holding layer can be applied, or different types of resins may be laminated.

In this aspect of 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 retroreflective sheet of the present invention is preferably formed using a glass sphere having a function of retroreflecting light in cooperation with the specular reflection layer located at the focal position. The refractive index of the glass sphere is 2.0 to 2.5, preferably 2.0 to 2.3.

The size of the glass sphere 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 it is the glass sphere that 1/15 or more of the diameter of the glass sphere is held by the transparent holding layer. This is preferable for supplying sufficient light. Furthermore, it is preferable that 1/5 or more of the diameter of the glass bulb is held by a transparent holding layer in order to supply sufficient light to the glass bulb.

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.

The retroreflective sheet of the present invention further has a focus forming layer shown in FIG. The focal point forming layer is a layer for disposing the specular reflection layer at the focal position of the glass sphere. 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, 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 substrate is not particularly limited as long as it has sufficient strength and expands and contracts sufficiently when heated, but is made of a material such as polyethylene terephthalate (PET), polyimide, vinyl chloride, or PP. Can be used, 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.

When the holding layer is a colored holding layer, a colored holding layer resin is applied on the surface protective layer and semi-dried. Next, a glass bulb is sprayed on the colored 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.

When the holding layer is a transparent holding layer and a colored holding layer, a transparent holding layer resin is applied on the surface protective layer and semi-dried. Next, the colored resin for the holding layer is coated on the semi-dried transparent holding layer and semi-dried.
Next, a glass bulb is sprayed on the colored 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.

Here, since the transparent holding layer is subjected to a drying process twice when the transparent holding layer is semi-dried and when the colored holding layer is semi-dried, the semi-drying of the transparent holding layer is colored. It is preferable that the holding layer can be applied and the drying is sweet.

By further processing after the glass spheres are dispersed, the glass spheres are embedded in the holding layer by the surface tension of the holding layer.

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 bulb. 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, sputtering, or the like can be used. In order to uniformly form a metal thin film reflecting the shape of the base, the 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 0.06 to 0.12 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 depends on the hue of the retroreflective sheet, but the front reflective performance (retroreflective performance at an incident angle of 0.2 ° and 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 The hue of the retroreflective sheet was measured according to JIS Z 9117 using a Nippon Denshoku color difference meter (Model SE-2000), 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) Evaluation of improvement of reflection performance At the driver's seat where the obtained retroreflective sheet lights the headlight at night, the front reflection performance (retroreflection performance at an incident angle of 0.2 ° and an observation angle of 5 °) 50 monitors of 18 to 60 years old judged visually whether it felt that there was an improvement.
Judgment criteria:
0 point: No improvement compared to the conventional same color reflective sheet 1 point: Slightly improved compared to the conventional same color reflective sheet 2 points: Good reflection performance compared to the conventional same color reflective sheet Yes, 3 points: Judgment results with superior reflection performance compared to conventional reflective sheets of the same color:
×: 30 points or less (no improvement in reflection performance)
Δ: 30 points or more and less than 90 (no improvement in reflection performance by the person observing)
○: 90 or more and less than 120 (good reflection performance)
A: 120 or more (excellent reflection performance)

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), 0.04 parts by weight of leveling agent (trade name, BYK-300) made by Big Chemie Japan, Dainippon Ink and Chemicals Co., Ltd. catalyst (trade name, Beccamin P-198) in 0.12 parts by weight, and MIBK / En = 8/2 by adding 16.7 parts by weight so that the ratio to form a surface protective layer having a thickness of 36μm was coated with a stirred mixture.

On the surface protective layer, 100 parts by weight of an acrylic resin (trade name RS-3000) manufactured by Onkiai Co., Ltd. and 12 weights of an isocyanate-based cross-linking agent (trade name, Sumidur N-75) manufactured by Sumitomo Bayer Urethane Co., Ltd. Into the surface, 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 70 ° C. for 5 minutes, 10 μm thick and 95% transmittance on the light incident side. A retention layer was obtained.
Next, RS-3000 is 100 parts by weight, Tokiki Co., Ltd. color base (trade name AR-4300) is 130 parts by weight, Sumidur N-75 is 21 parts by weight, Toluene is 21 parts by weight, and MIBK is 50 parts by weight. What was mixed and stirred was applied onto 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 50%.

A glass sphere (trade name, NB-45S) manufactured by Enkiai Co., Ltd. was attached to the holding layer on the focus forming layer side, and heat treatment was performed to submerge the glass sphere 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, the coating solution for the surface protective layer was 100 parts by weight of an acrylic resin solution (trade name, RS-1200) manufactured by Onki Aika Kako Co., Ltd., and a color base (trade name, AR-6100) manufactured by Tokushi Co., Ltd. 5 parts by weight, Tokushi Co., Ltd. color base (trade name, AR-6300) to 2.5 parts by weight, Miwa Chemical Co., Ltd. methylated melamine resin solution (trade name, Nicalac MS-11) 14 By weight, 4 parts by weight of cellulose derivative (trade name, CAB) manufactured by Special Color Co., Ltd., 0.5 parts by weight of UV absorber (trade name, Seasoap 103) manufactured by Sipro Kasei Co., Ltd., Big Chemie Japan Co., Ltd. Company leveling agent (trade name, BYK-300) is 0.04 part by weight, Dainippon Ink & Chemicals Co., Ltd. catalyst (trade name, Beccamin P-198) is 0.1. To the weight part, 13.1 parts by weight so that the ratio of MIBK / toluene = 8/2 was added as a solvent, and the mixture was stirred and mixed was used as the surface protective layer coating solution. As a coating solution, Sumitomo Chemical Co., Ltd. has 100 parts by weight of RS-3000, 32 parts by weight of Tokushiki Color Base (trade name AR-6300), 6 parts by weight of Tokushiki Color Base (trade name AR-6100). Using Joule N-75 mixed with 15 parts by weight of toluene, 5 parts by weight of toluene, and 12 parts by weight of MIBK mixed and stirred on the light-incident holding layer, dried at 100 ° C. for 5 minutes, A retroreflective sheet was obtained in the same manner as in Example 1 except that the holding layer on the side of the focus forming layer having a transmittance of 20% at 13 μm was obtained.

Example 3
In Example 1, the holding layer on the focus-forming layer side was RS-3000 100 parts by weight, Tokushi Co., Ltd. color base (trade name AR-6300) was 30 parts by weight, and Tokushi Co., Ltd. color base (trade name, AR -6300) to 10 parts by weight, Sumidur N-75 to 15 parts by weight, toluene to 5 parts by weight, and MIBK to 12 parts by weight. The film was dried for 5 minutes, and a retroreflective sheet was obtained in the same manner as in Example 1 except that the holding layer on the focus forming layer side having a thickness of 13 μm and a transmittance of 20% was obtained.

Comparative Example 1
In Example 1, the surface protective layer is 100 parts by weight of RS-1200, 26 parts by weight of a color base (trade name, AR-N-4100) manufactured by Tokiki Co., Ltd., and a methylated melamine resin manufactured by Sanwa Chemical Co., Ltd. 14 parts by weight of solution (trade name, Nicarak MS-11), 4 parts by weight of cellulose derivative (trade name, CAB) manufactured by Special Colorant Co., Ltd., and UV absorber (trade name, Sea Soap 103) manufactured by Sipro Kasei Co., Ltd. To 0.5 parts by weight, a leveling agent (trade name, BYK-300) manufactured by Big Chemie Japan Co., Ltd. is added to 0.04 parts by weight, and a catalyst (trade name, Beccamin P-198) manufactured by Dainippon Ink & Chemicals, Inc. is added. A surface protective layer having a thickness of 36 μm is applied by adding 16.7 parts by weight to 0.12 parts by weight as a solvent so that a ratio of MIBK / toluene = 8/2 is added and stirring. Formed, except that not provided holding layer focus forming layer side to obtain a retroreflective sheet in the same manner as in Example 1.

Comparative Example 2
In Comparative Example 1, the coating solution formulation for the surface protective layer is 100 parts by weight of RS-1200, the color base manufactured by Tokushi Co., Ltd. (trade name, AR-6100) is 15 parts by weight, and the color base manufactured by Tokushi Co., Ltd. (trade name) , AR-6300) and 11 parts by weight of methylated melamine resin solution (trade name, Nicalac MS-11) manufactured by Sanwa Chemical Co., Ltd. and 14 parts by weight of cellulose derivative (trade name, CAB) ) 4 parts by weight, Sipro Kasei Co., Ltd. UV absorber (trade name, Seasoap 103) 0.5 parts by weight, Big Chemie Japan Co., Ltd. leveling agent (trade name, BYK-300) 0.04 weight In a part, 0.12 part by weight of a catalyst (trade name, Becamine P-198) manufactured by Dainippon Ink & Chemicals, Ltd., and a ratio of MIBK / toluene = 8/2 as a solvent. In this way, 14.8 parts by weight are added, and the mixture which is stirred and mixed is applied to form a surface protective layer having a thickness of 36 μm. RS-3000) to 100 parts by weight, Tokiki Co., Ltd. color base (trade name, AR-6300) to 22 parts by weight, Sumitomo Bayer Urethane Co., Ltd. isocyanate-based cross-linking agent (trade name, Sumidur N-75). A retroreflective sheet was obtained in the same manner as in Example 1 except that 14 parts by weight, 20 parts by weight of toluene as a solvent, and 9 parts by weight of MIBK were mixed and stirred, and the holding layer on the focus forming layer side was not provided. It was.

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

It is sectional drawing of the enclosure lens type retroreflection sheet of this invention. 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, 3a, 3b Holding layer 4 Glass sphere 5 Focus forming layer 6 Specular reflection layer 7 Adhesive layer 8 Peeling base material 9 Incident direction of light

Claims (5)

In an encapsulated lens type retroreflective sheet composed of at least a surface protective layer and one or more holding layers for holding a glass sphere, a glass sphere, a focus forming layer, and a specular reflection layer, the holding layer has two or more layers, and light incident A holding layer on the side is transparent, and the holding layer contains 70% or more of the total amount of colorant contained in the surface protective layer and the holding layer of the retroreflective sheet. The retroreflective sheet according to claim 1, wherein the surface protective layer is colored. 3. The retroreflective sheet according to claim 1, wherein 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. The retroreflective sheet according to claim 3, wherein the distance is 5 μm or less. The retroreflective sheet according to any one of claims 1 to 4, wherein 1/15 or more of the diameter of the glass sphere is held in the transparent holding layer.