CN102439492A - Sealed lens type retroreflective sheeting - Google Patents

Abstract

The present invention provides a sealed lens type retroreflective sheeting, which has a higher retroreflective performance than the existing sealed lens type retroreflective sheeting. The sealed lens type retroreflective sheeting involved in the present invention is characterized in that: in the sealed lens type retroreflective sheeting having a surface protection layer (1), a retaining layer (3), a plurality of micro glass balls (4) retained by the retaining layer (3), a focus forming layer (5) and a mirror reflection layer (6), the average particle size of the micro glass balls (4) is in the range of 70μm to 100μm, and the particle size distribution is such that more than 75% of the particles are within the range of the average particle size ±10μm.

Description

Enclosed Lens Type Retroreflective Sheeting

technical field

The present invention relates to an enclosed lens type retroreflective sheeting. Specifically, it relates to markings such as road signs and construction signs, license plates of vehicles such as automobiles and motorcycles, clothing, safety equipment such as lifesaving appliances, signs such as signs, and various types of retroreflective sheeting. A lens-enclosed retroreflective sheeting that demonstrates excellent retroreflective performance on reflective plates such as labels, visible light, laser, or infrared reflective sensors.

More specifically, it relates to an enclosed lens type retroreflective sheeting having higher retroreflective performance than conventional enclosed lens type retroreflective sheetings.

Background technique

Conventionally, retroreflective sheeting that reflects incident light toward a light source has been widely known, and has been widely used for signs such as road signs and fortification signs, license plates of vehicles such as automobiles and motorcycles, clothing, and life-saving appliances. Equipment, signboards and other marks, various certification labels, reflective sensors for visible light, laser or infrared light, etc.

As such a retroreflective sheeting, there is known a capsule lens type retroreflective sheeting using a retroreflective element including micro glass spheres and a specular reflection layer on which a metal (usually aluminum) is vacuum-deposited. Or enclose lens type retroreflective sheeting.

As an example of a capsule lens type retroreflective sheeting, Mackenzie's JP-A No. 40-7870 (Patent Document 1, corresponding to US Patent No. 3,190,178 specification), McGrath's JP-A No. 52-110592 ( Patent Document 2 corresponds to US Patent No. 4,025,159), and Bailey's JP-A-62-121043 (Patent Document 3 corresponds to US Patent No. 5,064,272).

An example of an enclosed lens type retroreflective sheeting is disclosed in detail in Belisle, JP-A-59-71848 (Patent Document 4, corresponding to US Patent No. 4,721,649).

Regarding the retroreflection performance, because the combination of the observation angle and the light incident angle makes the observation angle and the required angle relative to the incident angle will be different, so it cannot be generalized, but about the observation at least 0.2 degrees to 0.5 degrees Angular Retroreflective Performance Capsule lens retroreflective sheeting generally has superior retroreflective performance over enclosed lens retroreflective sheeting.

However, with regard to the Y value used as an indicator of whiteness under natural light conditions, the enclosed lens type retroreflective sheeting is generally higher than the capsule lens type retroreflective sheeting. Furthermore, it is related to productivity, operability, and construction. The encapsulated lens retroreflective sheeting is also superior to the capsule lens retroreflective sheeting in terms of film stability such as no wrinkling after the rear.

patent documents

Patent Document 1: Japanese Patent Publication No. 40-7870

Patent Document 2: Japanese Patent Application Laid-Open No. 52-110592

Patent Document 3: Japanese Patent Application Laid-Open No. 62-121043

Patent Document 4: Japanese Patent Application Laid-Open No. 59-71848

Contents of the invention

Problems to be solved by the present invention

The enclosed lens type retroreflective sheeting as described above has good performance due to its high retroreflective performance and large Y value of reflected light, but it is further required to have excellent retroreflective performance in a direction closer to the front Enclosed lens type retroreflective sheeting. Here, an object of the present invention is to provide an enclosed lens type retroreflective sheeting having higher retroreflective performance than conventional enclosed lens type retroreflective sheetings in a direction relatively close to the front.

means of solving problems

In order to achieve the above object, the enclosed lens type retroreflective sheeting of the present invention is characterized in that it is equipped with a surface protection layer, a holding layer, a plurality of micro glass spheres held by the holding layer, a focus forming layer, and an enclosing layer of a specular reflection layer. In the lenticular retroreflective sheeting, the micro glass spheres have an average particle diameter in the range of 70 μm to 100 μm, and the particle size distribution is such that 75% or more of the particles are within the range of the average particle diameter ±10 μm.

According to such a lens-enclosed retroreflective sheeting, since the average particle size of the micro glass spheres is in the range of 70 μm to 100 μm, and the particle size distribution is such that more than 75% of the particles are within the range of the average particle size ± 10 μm, it is relatively close. High retroreflection performance can be achieved in the direction of the front. The reason for the high retroreflection performance in the direction relatively close to the front by using such micro glass spheres is not clear to the present inventors, but when the average particle diameter is less than 70 μm, it will be found that the luminous Extremely low. In addition, in the case where the average particle diameter exceeds 100 μm, it is considered that because it is necessary to form a thick focus-forming layer and the focus-forming layer tends to be skewed, the reflected light is scattered and compared to the reflected light in the direction closer to the front. The luminance drops. In addition, if the proportion of particles within the range of the average particle diameter ± 10 μm is less than 75%, the non-uniform ratio of the micro glass spheres increases, resulting in no formation of a particle at the focus of light emitted from the micro glass spheres. The ratio of the specular reflection layer becomes high. Therefore, it is considered that the reflected light is still scattered, and the luminance of the reflected light in a direction relatively close to the front is considered to be extremely lowered.

In addition, in the above-mentioned encapsulated lens type retroreflective sheeting, it is preferable that the average particle diameter of the micro glass spheres is 80 μm to 90 μm, and the particle size distribution of the particle diameters of the micro glass spheres is preferably within the range of the average particle diameter ± 10 μm. More than 80%.

According to such an enclosed lens type retroreflective sheeting, it is possible to have higher reflective performance.

In addition, in the above-mentioned enclosed lens type retroreflective sheeting, it is preferable that the retroreflective performance under the condition that the observation angle is 0.2 degrees and the incident angle is 5 degrees is 200 cd/lx/m2 or ^more , and it is more preferable that the observation angle is 0.2 degrees and 5 degrees. The retroreflection performance under the condition of an incident angle of 5 degrees is 250 cd/lx/m ² or more.

According to such an enclosed lens type retroreflective sheeting, since it has higher reflective performance, compared with the existing enclosed lens type retroreflective sheeting, the visibility at night is significantly improved, and it can be used for a wide range of products superior.

Invention effect

As described above, according to the present invention, it is possible to provide an enclosed lens type retroreflective sheeting having higher retroreflective performance than conventional enclosed lens type retroreflective sheetings in a direction relatively close to the front.

Description of drawings

FIG. 1 is a schematic diagram showing a cross-sectional structure of an enclosed lens type retroreflective sheeting according to an embodiment of the present invention.

Symbol Description

1…Surface protection layer

2…Print layer

3…Hold layer

4…Tiny glass spheres

5…focal cambium

6…Specular reflective layer

7...Adhesive layer

8...Peel off film

9...The direction of incidence of light

Implementation

Hereinafter, the enclosed lens type retroreflective sheeting of the present invention will be described in more detail by showing embodiments.

FIG. 1 is a schematic diagram showing a cross-sectional structure of an enclosed lens type retroreflective sheeting according to this embodiment. As shown in FIG. 1 , an enclosed lens type retroreflective sheeting 10 mainly includes a surface protection layer 1 , a holding layer 3 , a plurality of micro glass balls 4 held by the holding layer 3 , a focus forming layer 5 , and a specular reflection layer 6 .

In addition, in this embodiment, a printing layer 2 is provided for conveying information to an observer or for coloring a sheet. However, this printed layer 2 is not an essential configuration.

In the present embodiment, the surface protective layer 1 is a layer having a light transmittance with a total light transmittance of 80% or more, and is not particularly limited as long as it is a resin having such light transmittance, and is usually made of Acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, polyurethane resin, polycarbonate resin, etc., or a combination of these resins. In particular, acrylic resins, polyester resins, and vinyl chloride resins are preferable from the standpoint of weather resistance and workability, and among them, acrylic resins are particularly preferable in consideration of coating suitability and colorant dispersibility during coloring.

Various additives such as ultraviolet absorbers, stabilizers, plasticizers, and crosslinking agents can be added to the surface protection layer 1 within a range that does not significantly impair transparency.

When the colorant is contained in the surface protection layer 1, it is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and still more preferably 5 to 15 parts by weight, based on 100 parts by weight of the solid content of the matrix resin. share. If the amount of the coloring agent added is above the lower limit, it is preferable because sufficient coloring can be obtained and excellent visibility can be obtained. In addition, if the amount of the coloring agent added is below the upper limit, since it can prevent It is preferable that the retaining layer becomes too hard and becomes brittle, and also prevents properties such as mechanical strength and flexibility from being impaired.

In addition, if the light transmittance of the surface protection layer 1 is poor, it may become difficult to obtain excellent retroreflective performance, so the surface protection layer is preferably uncolored or colored with a colorant capable of obtaining transparency.

The holding layer 3 is a layer for holding the tiny glass balls 4 enclosed in the lens-type retroreflective sheeting 10, and is not particularly limited as long as it is a light-transmitting resin, and is usually made of acrylic resin, alkyd resin, fluororesin, chlorine, etc. It is composed of resins such as vinyl resin, polyester resin, polyurethane resin, and polycarbonate resin, or a combination of these resins. In particular, acrylic resins, polyester resins, and vinyl chloride resins are preferable from the standpoint of weather resistance and processability, and among them, acrylic resins are particularly preferable in consideration of coating suitability and colorant dispersibility during coloring.

The molecular weight of the resin forming the holding layer 3 is not particularly limited, but generally, the weight average molecular weight of the resin (hereinafter abbreviated as Mw) is preferably 50,000 or more, more preferably 50,000 to 400,000, and more preferably 100,000. In the range of 10,000 to 300,000, and by using a resin that reacts with an appropriate curing agent, it is possible to properly settle the micro glass balls 4 in the resin.

The solid content of the resin used for the holding layer 3 is usually 25 to 50%, preferably 30 to 40%, more preferably 33 to 38%. Furthermore, the thickness of the holding layer 3 is 15 μm to 50 μm. When the holding layer 3 is formed by laminating several layers, the coating thickness of the holding layer 3 holding the micro glass bulbs 4 is determined in consideration of conditions such as the diameter of the micro glass bulbs 4 .

In addition, in order to improve the retroreflection performance, the total light transmittance of the holding layer 3 is not particularly limited, but it is usually set to 80% or more, preferably 90% or more, more preferably 95% or more.

In addition, when the coloring agent is contained in the holding layer 3 , it may be the same as the case where the coloring agent is contained in the surface protection layer 1 .

In addition, various additives such as ultraviolet absorbers, stabilizers, plasticizers, and curing agents may be added to the holding layer 3 in addition to the colorant within a range that does not significantly impair its physical properties.

In addition, if necessary, curing agents such as alkylated amino resins, alkylated urea resins, and isocyanate-based crosslinking agents; release agents such as silicon-based release agents and cellulose-based release agents; Additives such as silicone-based siloxane, silicon-based surfactants, acrylic polymers and other surface conditioners.

A plurality of minute glass balls 4 are held in the holding layer 3 . The tiny glass balls 4 have the function of retroreflecting light through the cooperation of the focus forming layer 5 and the specular reflection layer 6 , wherein the specular reflection layer 6 is opposite to each micro glass ball 4 . The refractive index of the micro glass bulb 4 is normally 2.0-2.5, Preferably it is 2.0-2.3.

In addition, in the present embodiment, the average particle diameter of the micro glass bulbs 4 used as an element of retroreflected light is 70 μm to 100 μm. Thus, by increasing the average particle diameter of the micro glass spheres 4, the front reflection performance of the enclosed lens type retroreflective sheeting 10 can be improved compared to the prior art. In addition, the average particle diameter of the micro glass spheres 4 is more preferably 80 μm to 90 μm.

In addition, in the present embodiment, the particle size distribution of the particle size of the micro glass spheres 4 occupies 75% or more within the range of the average particle size ±10 μm. In addition, it is more preferable that the particle size distribution accounts for 80% or more within the range of the average particle diameter ±10 μm. Thus, by narrowing the particle size distribution, the light incident on the micro glass spheres 4 from the front passes through the focus forming layer 5 described later and is reflected by the specular reflection layer 6 , the focal point is connected by the specular reflection layer 6 and retroreflected. The ratio of will be larger and the retroreflection performance will be improved.

In addition, the measurement of the average particle diameter and particle size distribution of the said micro glass sphere 4 was performed as follows. First, 10 g of micro glass balls 4 as a measurement sample were weighed in a dry glass container. Next, about 230 ml of an electrolyte solution manufactured by BECKMAN (trade name: Coulter Isoton III Diluent) was put into the container, and stirred with a glass rod until uniformly dispersed, thereby preparing a dispersion solution of the micro glass spheres 4 . Next, the dispersion solution was measured in a Coulter counter (Multisizer 2) manufactured by BECKMAN.

In addition, the focus forming layer 5 is a layer for arranging the specular reflection layer 6 at the focus position of light passing through each micro glass sphere 4, and is not particularly limited as long as it is a light-transmitting resin, and is usually made of Acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, polyurethane resin, polycarbonate resin, butyral resin, or a combination of these resins. In particular, it is preferably composed of an acrylic resin or a butyral resin from the viewpoint of weather resistance, coating suitability, and thermal stability.

Various additives such as colorants, ultraviolet absorbers, stabilizers, plasticizers, and crosslinking agents can be added to the focus forming layer 5 within a range that does not significantly impair transparency.

The molecular weight of the resin forming the focus forming layer 5 is not particularly limited, but usually the Mw of the resin forming the focus forming layer 5 is 100,000 or more, more preferably 100,000 to 400,000, and more preferably 150,000. ~300,000. By controlling Mw within this range and using a resin that reacts with an appropriate curing agent, it is possible to more properly form the spherical focus forming layer 5 .

The viscosity of the resin forming the focus forming layer 5 at the time of application is usually 10 to 600 cP, preferably 30 to 600 cP, more preferably 50 to 200 cP. In addition, the solid content of the resin of the focus forming layer 5 is usually 10 to 40%, preferably 15 to 35%, and more preferably 15 to 25%. This is because when the resin solid content is high, air bubbles are easily entrapped and foaming is likely to occur, and when the solid content is less than 10%, the coating amount becomes considerably large.

Although the thickness of the focal point forming layer 5 is determined in consideration of the refractive index of the resin so that the incident light is connected to the focal point on the specular reflection layer 6, it is usually set to 10 μm to 60 μm, preferably 15 μm to 50 μm, and particularly preferably set to 10 μm to 60 μm. 20 μm to 40 μm.

In the present invention, the total light transmittance of the focus forming layer 5 is preferably 80% or higher, more preferably 90% or higher, and particularly preferably 95% or higher in order to improve retroreflective performance.

In addition, the specular reflection layer 6 is a layer for reflecting light, and is generally composed of metals such as aluminum, silver, chromium, nickel, magnesium, gold, and tin. The specular reflection layer 6 is formed using these metals by means of vacuum evaporation, sputtering, or the like. In addition, the vacuum vapor deposition method is particularly preferable in order to uniformly form a metal thin film reflecting the shape of the base. In addition, the thickness of the metal reflective layer is usually 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, and particularly preferably 0.05 μm to 0.1 μm.

In addition, as shown in FIG. 1 , the enclosed lens type retroreflective sheeting 10 of the present embodiment has an adhesive layer 7 for bonding to a substrate such as an aluminum plate or an acrylic plate. The type of resin constituting the adhesive layer 7 is not particularly limited, and resins used as ordinary adhesive resins may be used, for example, acrylic resins, silicone resins, rubber resins, phenolic resins, etc. wait. Among them, an acrylic resin or a silicone resin that is excellent in weather resistance and has good adhesive properties is preferable.

The resin constituting the adhesive layer 7 is not particularly limited, but there is a tendency that the higher the molecular weight of the resin, the easier it is to obtain a suitable holding force. Usually, a resin with a Mw of 500,000 or more is used, and more preferably, a resin with a Mw of 500,000 to 1.2 million is used. As for the resin, it is more preferable to use 600,000 to 1,000,000 resins. Among them, when the resin used is obtained by crosslinking a resin having a functional group with a Mw of 500,000 or more using an isocyanate crosslinking agent, particularly excellent holding power can be obtained, and therefore it is most preferable.

Adhesive layer 7 can be arranged on the specular reflection layer 6 side, so that the enclosed lens type retroreflective sheeting 10 can be pasted on the substrate through the adhesive layer 7, and a light-transmitting adhesive layer can also be arranged on the enclosed surface. The light-incident side of the lens-type retroreflective sheeting 10 (the surface protection layer 1 side), the enclosed lens-type retroreflective sheeting 10 is attached to the light-transmitting substrate through the adhesive layer.

In addition, since the peeling film 8 is provided on the side opposite to the specular reflection layer 6 side of the adhesive layer 7, it is possible to prevent the adhesive layer 7 from adhering to a place where adhesion is not desired.

The retroreflective performance of the enclosed lens type retroreflective sheeting 10 is preferably 180 cd/lx/m ² or more, more preferably 200 cd, under the condition that the observation angle is 0.2 degrees and the incident angle is 5 degrees. /lx/m ² or more, more preferably 220 cd/lx/m ² or more, most preferably 250 cd/lx/m ² or more. By having such retroreflective performance, nighttime visibility can be significantly improved compared to conventional enclosed lens type retroreflective sheeting.

In addition, the enclosed lens type retroreflective sheeting 10 is manufactured by the method described below. First, a resin compound solution for the surface protection layer of the engineering base material is applied and dried to form the surface protection layer 1 . As long as the engineering base material has sufficient strength and sufficiently small expansion and shrinkage when heated, there are no special restrictions, and polyethylene terephthalate (PET), polyimide, etc. can be used. , vinyl chloride and the like as the base material, among which PET is particularly preferable.

The coating method is not particularly limited as long as it can uniformly coat a predetermined thickness, but methods such as reverse roll coating and comma direct coating are preferably used.

Next, the resin compound solution for the holding layer 3 is applied on the surface protection layer 1 and then semi-dried. Next, micro glass balls 4 are scattered on the resin in a semi-dried state, and heat-treated. The embedding rate can be adjusted by embedding the micro glass bulbs 4 in the resin to be semi-dry to the degree of semi-dryness of the resin constituting each protective layer 3 . As the heat treatment temperature after the fine glass balls 4 are dispersed, for example, when an acrylic resin is used as the resin, it is usually 50°C to 150°C, preferably 70°C to 130°C, and particularly preferably 80°C to 120°C. It is dried for about 5 minutes under temperature conditions, as long as it is easy to embed the tiny glass balls 4 . By drying the semi-dried resin in this way, the holding layer 3 holding the micro glass spheres 4 is formed.

The embedding rate of the tiny glass balls 4 in the holding layer 3 is not particularly limited, and varies depending on the type of resin of the holding layer 3. For example, when an acrylic resin is used as the resin of the holding layer 3, With respect to the diameter of the micro glass sphere 4, it is preferably 20% or more.

In addition, in the existing lens-enclosed retroreflective sheeting, the embedding rate of the tiny glass balls 4 in the holding layer 3 is about 50%, because the front reflection performance of the lens-enclosed retroreflective sheeting 10 can be improved. Preferably, but in this embodiment, the focus forming layer 5 is relatively thin, because it is easy to form the focus forming layer 5 and the spherical surface of the micro glass sphere 4, so it is preferable to form the focus forming layer thinner as described above. 5. The embedding rate of the micro glass spheres 4 is preferably 50 to 90%, more preferably 70 to 80%. In addition, the thickness of the focus forming layer 5 tends to become thicker as the micro glass spheres 4 become larger. However, by controlling the embedding rate of the micro glass balls 4 to 50% to 90% as described above, the focus forming layer 5 can be thinned and the material of the focus forming layer 5 can be prevented from becoming thicker. bubble etc.

Next, the resin compound solution for the focus forming layer 5 is applied to the micro glass spheres 4 and the holding layer 3 holding the micro glass spheres 4 . The coating method is not particularly limited as long as it can uniformly coat a predetermined thickness, but methods such as reverse roll coating and comma direct coating are preferably used.

The resin compound solution for the focus forming layer 5 is applied at room temperature, and if necessary, heat-treated to harden the resin. The curing temperature varies depending on the type of resin and curing agent, but when an acrylic resin is used as the resin for the focus forming layer, it is usually 50°C to 160°C, preferably 70°C to 155°C. The heating time is set to 3 minutes to 10 minutes. In addition, the resin compounding liquid for the focus forming layer 5 may be applied and cured several times as needed. In this way, the focus forming layer 5 is formed by curing the resin compounding liquid.

Next, the specular reflection layer 7 is formed on the focus forming layer 5 from a metal thin film. The metal thin film may be formed by a coating method, a vacuum vapor deposition method, etc., but the vacuum vapor deposition method is particularly preferable in order to uniformly form a metal thin film reflecting the shape of the base. The thickness of the metal layer is not particularly limited, but is usually 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, and particularly preferably 0.05 to 0.1 μm.

Conditions such as vapor deposition rate, temperature, and degree of vacuum can be appropriately selected according to the machine, and the metal thin film can be uniformly formed to a predetermined thickness.

In addition, in the case of holding the adhesive layer 7 like the enclosed lens type retroreflective sheeting 10 shown in FIG. After drying, the surface of the intermediate product after forming the specular reflection layer 6 is bonded to the surface of the adhesive layer. Bonding conditions vary depending on the adhesive constituting the adhesive layer, but when an acrylic resin is used as the adhesive, for example, it is preferable to apply pressure while heating to about 50 to 90°C.

Finally, when the process substrate is peeled off, the enclosed lens type retroreflective sheeting 10 having an adhesive layer of the present invention can be obtained.

Example

Hereinafter, examples and comparative examples will be given to describe the present invention in detail. In addition, the measuring method used in the Example and the comparative example is as follows.

(retroreflection performance)

As a retroreflective performance measuring device, "Model 920" manufactured by Advanced RetroTechnology, INC. was used, based on JIS Z 9117, and the incident angle was set to 5 degrees, and the observation angle was 0.2 degrees and the observation angle was 0.5 degrees. The amount of retroreflected light of a 100 mm×100 mm retroreflective sheeting sample was measured at 5 points, and the average value of these 5 points was taken as the value of retroreflective performance. Also, in actual use, usually the incident angle of 5 degrees is relatively close to the front of the retroreflective sheeting and is a small incident angle, and the observation angle of 0.2 degrees is a relatively small observation angle. In addition, the observation angle of 0.5 degrees is not close to the front of the retroreflective sheeting and is not a small observation angle.

<Example 1>

As the process substrate, a transparent polyethylene terephthalate film (trade name: Teijin TETORON Film S-75) with a thickness of 75 μm manufactured by Teijin Corporation was used. Then, a resin compound solution for forming a surface protection layer was coated on the process base material and dried to form a colorless and transparent surface protection layer with a thickness of about 40 μm. Wherein, the resin complex solution for the formation of the surface protection layer is to add: Japan SANWA CHEMICAL Co., Ltd. 14 parts by weight of methylated melamine resin solution (trade name: NIKALAC MS-11), 4 parts by weight of cellulose derivative (trade name: CAB) manufactured by Japan TOKUSHIKI Co., Ltd., Japan SHIPRO KASEI Co., Ltd. 0.5 parts by weight of UV absorber (trade name: SEESORB 103) made by . Japan BYK-CHEMIE JAPAN KK (trade name: BYK-300) 0.04 parts by weight, catalyst (trade name : BECKAMINE P-198) 0.12 parts by weight, and MIBK/toluene = 8/2 ratio as a solvent 16.7 parts by weight, and then stirred and mixed.

Next, a resin compound solution for forming a holding layer was applied on the surface protection layer, and then dried at 70° C. for 5 minutes to form a holding layer having a thickness of about 30 μm. Wherein, the resin compound solution for the formation of the retaining layer is 100 parts by weight of acrylic resin solution (trade name: RS-3000) manufactured by Enciai Co., Ltd., and isocyanate crosslinking solution manufactured by Sumika Bayer Urethane Co., Ltd., Japan. Add 36 parts by weight of MIBK to 12 parts by weight of solvent (trade name: SUMIDUR N-75) and 15 parts by weight of toluene as a solvent, and then stir and mix.

Micro glass spheres (trade name: NB K1028) manufactured by Enrichia Co., Ltd. having the average particle diameter shown in Table 1 and having a particle size distribution within the range of the average particle diameter ± 10 μm in the ratio shown in Table 1 Attached to the above-mentioned holding layer, heat treatment was performed, and the micro glass spheres were allowed to settle in the holding layer in the form that the micro glass spheres were exposed from the holding layer. In addition, when the cross-section was observed with a microscope, it was confirmed that the micro glass spheres were in contact with the surface protection layer, and approximately 75% of the diameter of the micro glass spheres was retained in the holding layer.

Next, a resin compound solution for forming a focus layer was applied on the holding layer and the micro glass beads and dried to form a focus forming layer with an average thickness of about 23 μm. The resin complex liquid that described focus layer is formed is to add the acrylic resin solution (trade name: RS-5000) 100 parts by weight of Enciai Chemical Co., Ltd. system, Japan SANWA CHEMICAL Co., the methylated melamine resin solution of Ltd. system (trade name: NIKALAC MS-11) 5.5 parts by weight, and 39.3 parts by weight of a solvent at a ratio of MIBK/toluene=4/6, and then stirred and mixed.

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

In addition, as the release paper, the release paper (trade name: E2P-H(P)) manufactured by LINTEC Corporation Co., Ltd. in Japan is used, and the resin compound solution for forming the adhesive layer is coated on the release paper and dried. Thus, an adhesive layer having a thickness of about 41 μm was formed. Wherein, the resin compound solution for the formation of the adhesive layer is an ethyl acetate/toluene (1/1) solution (solid content 34%) added with BA/AA copolymer (weight ratio: BA/AA=90/10) ) 100 parts by weight, 9 parts by weight of white coloring agent (trade name: AR-9127W) made by Japan TOKUSHIKI Co., Ltd., isocyanate crosslinking agent (trade name: CORONATE L) 0.5 parts by weight and 16.1 parts by weight of ethyl acetate as a solvent were stirred and mixed.

Next, after laminating the specular reflection layer and the adhesive layer, the engineered substrate was peeled off to obtain a lens-enclosed retroreflective sheeting having an adhesive layer.

<Example 2>

Except that the tiny glass spheres used in Example 1 were changed to have the average particle diameter shown in Table 1, and the particles whose particle size distribution is within the range of the average particle diameter ± 10 μm are the ratios shown in Table 1 Enciai Chemical Co., Ltd. Except for the tiny glass spheres (trade name: NB K0922-1), all the others were prepared in the same manner as in Example 1 to obtain an enclosed lens-type retroreflective sheeting with an adhesive layer.

<Example 3>

Except that the micro glass spheres used in Example 1 were changed to the Japanese UNION CO. , LTD made of micro glass balls (trade name: UB-B), the rest were the same method as in Example 1 to produce a sealed lens type retroreflective sheeting.

<Example 4>

Except that the micro glass spheres used in Example 1 were changed to the Japanese UNION CO. , LTD made of micro glass balls (trade name: UB-C), the rest were made in the same manner as in Example 1 to obtain an enclosed lens type retroreflective sheeting.

<Example 5>

Except that the micro glass spheres used in Example 1 were changed to Japanese ASAHI TECHNO GLASS having the average particle diameter shown in Table 1, and the particle size distribution being within the range of the average particle diameter ±10 μm to the ratio shown in Table 1 A lens-encapsulated retroreflective sheeting was produced in the same manner as in Example 1, except for micro glass spheres manufactured by CO., LTD. (trade name: SK-80).

<Example 6>

Except that the micro glass spheres used in Example 1 were changed to Japanese ASAHI TECHNO GLASS having the average particle diameter shown in Table 1, and the particle size distribution being within the range of the average particle diameter ±10 μm to the ratio shown in Table 1 A lens-encapsulated retroreflective sheeting was produced in the same manner as in Example 1, except for micro glass spheres manufactured by CO., LTD. (trade name: SK-73).

<Comparative example 1>

As Comparative Example 1, an enclosed-lens type retroreflective sheeting (trade name: 1801220AN, lot number: K266C) manufactured by Enrichia Co., Ltd. was used. Among them, this enclosed lens type retroreflective sheeting is manufactured by Enciai Co., Ltd. with the average particle diameter shown in Table 1 and the particle size distribution in the range of the average particle diameter ± 10 μm in the ratio shown in Table 1. Micro glass balls (trade name: NB45) to be manufactured.

<Comparative example 2>

As Comparative Example 2, an enclosed lens-type retroreflective sheeting (trade name: 0811200AI, lot number: P870G) manufactured by Enrichia Co., Ltd. was used. Among them, this enclosed lens type retroreflective sheeting is manufactured by Enrichment Co., Ltd., which has the average particle diameter shown in Table 1 and the particle size distribution in the range of the average particle diameter ± 10 μm in the ratio shown in Table 1. Micro glass balls (trade name: NB34) to be manufactured.

<Comparative example 3>

The micro glass spheres used in the enclosed lens type retroreflective sheeting of Comparative Example 1 were screened to have the average particle diameter shown in Table 1 and the particles within the range of the average particle diameter ±10 μm to the ratio shown in Table 1. Microscopic glass spheres with particle size distribution. Then, using the micro glass spheres, a lens-enclosed retroreflective sheeting was produced in the same manner as in Example 1.

<Comparative example 4>

The micro glass spheres used in the enclosed lens type retroreflective sheeting of Comparative Example 1 were screened to have the average particle diameter shown in Table 1 and the particles within the range of the average particle diameter ±10 μm to the ratio shown in Table 1. Microscopic glass spheres with particle size distribution. Then, using the micro glass spheres, a lens-enclosed retroreflective sheeting was produced in the same manner as in Example 1.

The retroreflective properties of Examples 1 to 6 and Comparative Examples 1 to 4 thus obtained were measured according to the above-mentioned measurement method. The results are shown in Table 1.

[Table 1]

As shown in Table 1, the average particle diameters of the micro glass spheres in Examples 1-6 are all within the range of 70 μm to 100 μm, and the particle size distribution is such that more than 75% of the particles are within the range of the average particle diameter ±10 μm. In addition, the particle size distribution of the particle size of the micro glass spheres of Comparative Examples 1 and 3 was less than 75% within the range of the average particle size ±10 μm. In addition, the average particle diameter of the micro glass sphere of the comparative example 2 was outside the range of 70 micrometers - 100 micrometers. In addition, the particle size distribution of the particle size of the glass microspheres in Comparative Example 4 was less than 75% within the range of the average particle size ±10 μm, and the average particle size of the glass microspheres was outside the range of 70 μm to 100 μm.

In addition, in Examples 1 to 6, as shown in Table 1, the light intensity of the retroreflected light was 260 cd/lx/m ² or more under the condition that the observation angle was 0.2 degrees. On the other hand, in Comparative Examples 1 to 4, as shown in Table 1, the light intensity of the retroreflected light was 200 cd/lx/m ² or less under the condition that the observation angle was 0.2 degrees. Therefore, Examples 1-6 showed more excellent retroreflection performance than Comparative Examples 1-4 in the direction relatively close to the front. Furthermore, as shown in Table 1, under the condition that the observation angle is 0.5 degrees, the light quantity of the retroreflected light in Examples 1 to 6 is 75 cd/lx/m ² or more, and the light quantity of the retroreflected light in Comparative Examples 1 to 4 is 73 cd /lx/ ^m2 or less. Therefore, Examples 1-4 showed retroreflection performance more than the same level compared with Comparative Examples 1-4 in the direction deviated relatively from the front.

From the above, it can be seen that Examples 1 to 6, which are the enclosed lens type retroreflective sheetings of the present invention, have higher reflectivity in the direction closer to the front than Comparative Examples 1 to 4 which are conventional enclosed lens type retroreflective sheetings. radiation performance.

Industrial Utilization Possibility

According to the present invention, it is possible to provide an enclosed lens type retroreflective sheeting having higher retroreflective performance than conventional enclosed lens type retroreflective sheetings in a direction relatively close to the front.

Claims (5)

1. A lens-enclosed retroreflective sheeting, characterized in that: In the enclosed lens type retroreflective sheeting equipped with a surface protection layer, a holding layer, a plurality of micro glass spheres held by the holding layer, a focus forming layer, and a specular reflection layer, The average particle diameter of the tiny glass balls is in the range of 70 μm to 100 μm, and the particle size distribution is such that more than 75% of the particles are within the range of the average particle diameter ±10 μm. 2. Enclosed lens type retroreflective sheeting as claimed in claim 1, is characterized in that: The average particle size of the micro glass spheres is 80 μm to 90 μm. 3. Enclosed lens type retroreflective sheeting as claimed in claim 1 or 2, is characterized in that: The particle size distribution of the micro glass spheres accounts for 80% or more within the range of the average particle diameter ±10 μm. 4. The enclosed lens type retroreflective sheeting according to any one of claims 1 to 3, characterized in that: The retroreflection performance under the condition that the observation angle is 0.2 degrees and the incident angle is 5 degrees is 200 cd/lx/m ² or more. 5. The enclosed lens type retroreflective sheeting according to any one of claims 1 to 3, characterized in that: The retroreflection performance under the condition that the observation angle is 0.2 degrees and the incident angle is 5 degrees is 250 cd/lx/m ² or more.

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