JP3815972B2 - Retroreflective sheet and manufacturing method thereof - Google Patents

Description

【００６４】
【発明の効果】
本発明は、再帰反射性要素として、ガラスビーズを封入した結合剤層と該結合剤層の背面に位置する焦点層を有し、接着剤層を有するガラスビーズ封入型再帰反射シートにおいて、表面粗さRaを0.1〜1.0μmとすることにより、帯電防止効果に優れた表示板用再帰反射シートを提供するものである。
【図面の簡単な説明】
【図１】本発明の再帰反射シートの一態様である封入レンズ型再帰反射シートの断面構成概略図を示したものである。
【符号の説明】
１・・・・・・微小球レンズ
２・・・・・・結合剤層
３・・・・・・焦点層
４・・・・・・光反射層
５・・・・・・接着剤層
６・・・・・・基材[Industrial application fields]
The present invention relates to retroreflective sheets useful for signs such as road signs and construction signs, number plates (car license plates) for automobiles and motorcycles, or safety materials such as life-saving clothing, and particularly for printing numbers and letters. In addition, the present invention relates to a retroreflective sheet that is useful in applications in which a resin plate is attached to the plate and used as a plate.
[0001]
[Prior art]
Conventionally, a retroreflective sheet for retroreflecting light toward a light source is well known, and the sheet is used in the fields of use as described above by utilizing the retroreflective property. In recent years, excellent visibility at night based on the retroreflective performance of the retroreflective sheet has become widely accepted. Especially, the plate with the retroreflective sheet attached is not only for signs but also according to the laws and regulations of each country. It is becoming mandatory as a plate (car license plate).
[0002]
In recent years, display plates such as license plates have become multi-colored, using a retroreflective sheet as a base, printing various displays with multi-colors using a thermal transfer printer capable of multi-color printing, and then forming a transparent surface protection plate on the surface A retroreflective display plate is created by pasting.
[0003]
However, when multi-color printing is performed on a conventional retroreflective sheet using a thermal transfer printer, static electricity is charged on the sheet, causing a problem of damaging the print head. Also, when static electricity was charged, it was not possible to feed one sheet at a time in the case of sheet-fed printing, and in the case of continuous printing, a foil adhered to the sheet and printing could not be performed well.
[0004]
As a method of using the antistatic agent, a method of applying an antistatic agent mainly composed of a hydrophilic or conductive resin to the sheet surface, a method of kneading the antistatic agent into the sheet resin, or the like has been tried.
[0005]
However, the method of applying an antistatic agent to the surface decreases with time even if an antistatic effect is obtained immediately after application.
[0006]
The method of kneading the antistatic agent into the sheet resin is difficult to obtain a sufficient antistatic effect for the entire sheet for a long period of time, and the use of a large amount of the antistatic agent depends on the physical characteristics of the sheet or optical properties. In some cases, the use of a label or the like is insufficient.
[0007]
On the other hand, as a method of providing irregularities on the sheet surface, the glass beads are not completely embedded in the resin, but are embedded in the sheet by leaving the glass beads protruding from the sheet by several% of the diameter of the glass beads. Then, there was a method of providing irregularities on the surface.
[0008]
However, in the open bead type retroreflective sheet, the surface becomes a non-uniform surface where exposed portions of beads are mixed in the sheet portion, and depending on the manufacturing conditions, fading or poor adhesion may occur during printing. The printability was not satisfactory. Also, because of its structure, it is difficult to maintain strength, and some kind of reinforcement measures must be taken. [Problems to be solved by the invention]
[0009]
An object of the present invention is to provide an excellent retroreflective sheet having excellent antistatic properties and printability and a method for producing the same.
As a result of various investigations on the retroreflective sheet and its manufacturing method, the present inventors have achieved excellent antistatic properties and printability by setting the surface roughness Ra of the encapsulated retroreflective sheet to 0.1 to 1.0 μm. Has been found, and the present invention has been completed.
[0010]
[Means for Solving the Problems]
Thus, according to the present invention, an encapsulated retroreflective sheet having a retroreflective element layer and an adhesive layer has a surface roughness Ra of 0.1 to 1.0 μm and a method for producing the retroreflective sheet. Provided.
[0011]
Hereinafter, the retroreflective sheet of the present invention will be described in more detail.
FIG. 1 is a schematic cross-sectional view of an encapsulated lens type retroreflective sheet which is an embodiment of the retroreflective sheet of the present invention. The encapsulated lens type retroreflective element of the present invention includes a microsphere lens layer 1 made of a glass sphere having a refractive index of about 2.1 to 2.3 that functions as a lens, and a bond made of a transparent resin for bonding and fixing the microsphere lens. It consists of a focal layer 3 made of a transparent resin or the like for forming an agent layer 2 and a light reflecting layer 4 such as an aluminum vapor deposition film at the optical focal position of the lens. An adhesive layer 5 having excellent holding power and excellent wettability is formed on the back surface of the retroreflective element layer, and a release substrate 6 for protecting the adhesive layer is provided on the back surface of the adhesive layer. It has been.
[0012]
The resin that forms the binder layer is not particularly limited, and examples thereof include acrylic resins, polyester resins, alkyd resins, butyral resins, and urethane resins. 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.
[0013]
These resins may contain additives such as a curing agent, a release agent, and a surface conditioner as necessary.
Examples of the release agent include a silicon release agent and a cellulose release agent, and a cellulose release agent is preferable from the viewpoint of printability.
[0014]
Examples of the curing agent include alkylated amino resins, alkylated urea resins, isocyanate-based crosslinking agents, and the like, and alkylated amino resins and isocyanate-based crosslinking agents are preferable from the viewpoints of glass beads embedding property, weather resistance, and peelability.
[0015]
Examples of the surface conditioner include polyester-modified polydimethylsiloxane, silicon-based surfactant, acrylic polymer, and the like, and polyester-modified polydimethylsiloxane is preferable from the viewpoint of printability, wettability, and heat resistance.
[0016]
The molecular weight of the resin forming the binder 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. More preferably, a resin of 100,000 to 300,000 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 binder layer can be applied in several steps as required, and different types of resins may be laminated.
[0017]
The viscosity at the time of coating of the binder layer resin to be coated on the process substrate is a coating temperature, and is 80 to 400 cP, preferably 90 to 350 cP, and more preferably 100 to 300 cP.
[0018]
As will be described later, in the present invention, a process base material having a rough surface different from the conventional base material is used as the process base material. Therefore, a binder layer resin having a viscosity within an appropriate range is used at the time of coating. It is necessary to prevent foaming of the binder layer. If the viscosity is too high, air escape is particularly poor at the concave portions of the base material, and the binder layer contains bubbles. If the viscosity is too low, sufficient coating cannot be performed.
[0019]
The resin solid content of the binder layer resin is 25 to 50%, preferably 30 to 40%, more preferably 33 to 38%.
[0020]
The resin coating thickness of the binder layer is 15 μm to 50 μm. When several layers are laminated, the coating thickness of the binder layer holding the beads is determined in accordance with conditions such as the bead diameter, but is usually 18 μm to 33 μm, preferably 20 μm to 30 μm.
[0021]
The surface of the binder layer is uneven to reflect the surface shape of the process substrate described later. The surface roughness Ra is 0.1 to 1.0 μm, preferably 0.3 to 0.8 μm, and particularly preferably 0.5 to 0.8 μm. If the surface roughness is 1.0 μm or more, peeling between the binder layer and the process substrate becomes difficult, and if it is 0.1 μm or less, the antistatic effect cannot be obtained.
[0022]
The shape of the unevenness is not particularly limited, but the resin surface has a regular or irregular sheet having a convex part of 0.1 μm to 10 μm, a sheet having a regular or irregular shape of a concave part of 0.1 μm to 10 μm, Considering that there are 1 μm to 10 μm wide linear projections, 1 μm to 10 μm wide grooves, etc., and that it can be easily manufactured using process bases with irregularities by the blast method, A sheet having irregularities of 0.1 μm to 10 μm with an irregular resin surface is preferable.
[0023]
Glass balls serving as lenses are enclosed in the binder layer. The refractive index of the glass sphere is 2.0 to 2.5, preferably 2.19 to 2.21, and the diameter of the glass sphere is 20 μm to 110 μm, preferably 30 μm to 100 μm, particularly preferably 45 μm to 90 μm.
[0024]
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.
[0025]
These resins may contain additives such as a curing agent as necessary. Examples of the curing agent include alkylated amino resins, alkylated urea resins, isocyanate-based crosslinking agents, and the like, and alkylated amino resins are preferred from the viewpoint of spherical surface formation.
[0026]
The molecular weight of the resin forming the focal layer is not particularly limited, but the resin has a Mw of 100,000 or more, more preferably 100,000 to 400,000, and even more preferably 150,000 to 300,000. Should be used. When a resin within this range and reacted with an appropriate curing agent is used, a spherical focal layer can be formed.
[0027]
The viscosity at the time of application of the resin forming the focal layer is 10 to 600 cP, preferably 30 to 600 cP, and more preferably 50 to 200 cP.
[0028]
The resin solid content of the focal layer resin is 10 to 40%, preferably 15 to 35%, and more preferably 15 to 25%. When there is a lot of resin solids, it becomes easy to foam,
If it is less than 10%, the coating amount becomes considerably large, which is not preferable.
[0029]
The thickness of the focus resin layer is determined in consideration of the refractive index of the resin so that the incident light beam is focused on the light reflection layer, but is usually 10 μm to 60 μm, preferably 15 μm to 50 μm, particularly preferably 20 μm. ~ 40 μm.
[0030]
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.
[0031]
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.
[0032]
The retroreflective sheet of the present invention is manufactured by the method described below.
First, the binder layer resin described above is applied to the process substrate.
The process substrate has fine irregularities on the surface, the surface roughness Ra is 0.1 to 1.0 μm, preferably 0.3 to 0.8 μm, has sufficient strength, and expands and contracts when heated. Although it will not be restrict | limited especially if it is small enough, base materials of materials, such as a polyethylene terephthalate (PET), a polyimide, a vinyl chloride, can be used, and PET is especially preferable.
[0033]
Among the PET base materials, sand matt PET whose surface is sandblasted, coated with a matting agent on the surface, or chemical mat PET with a matting agent kneaded can be used. From the viewpoint of properties, sand mat PET is particularly preferable.
[0034]
The surface roughness of the sand mat PET also corresponds to the gloss of the PET surface, and the surface gloss (60 °) is preferably 2 to 20%, particularly preferably 4 to 15%.
[0035]
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.
[0036]
Next, glass beads are sprayed on the binding resin coating layer. The temperature of the binder resin layer when spraying varies depending on the resin. For example, when acrylic is used as the resin, it is heated to 50 ° C to 150 ° C, preferably 70 ° C to 130 ° C, particularly preferably 80 ° C to 120 ° C. The glass beads should be easily settled.
[0037]
The sedimentation rate of the glass beads is not particularly limited and varies depending on the type of binder resin. For example, when acrylic is used as the resin, it should be 1% or more from the viewpoint of retaining the beads. .
[0038]
Further, the resin is cured by heat treatment. The curing temperature varies depending on the type of resin / curing agent, but when an acrylic resin is used as the binder layer, it is preferably heated to 100 ° C. or higher, preferably 100 ° C. to 160 ° C.
[0039]
Next, the focal 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.
[0040]
Apply at room temperature and heat-treat as necessary to cure the resin. The curing temperature varies depending on the type of resin / curing agent, but when an acrylic resin is used as the focal layer resin, it is preferably heated to 50 ° C. to 160 ° C., preferably 70 ° C. to 155 ° C. Moreover, you may apply | coat a focal layer in several times as needed.
[0041]
Next, a metal thin film is formed on the focal layer. As a method for forming the metal thin film, a coating method, a vapor deposition method, or the like can be used. However, the vapor deposition method is particularly preferable in order to uniformly form the metal thin film reflecting the shape of the base. The thickness of the metal layer is 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, particularly preferably 0.05 to 0.1 μm.
[0042]
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. .
[0043]
Next, the adhesive layer described above is applied onto the release film, and bonded to the intermediate product after metal deposition on the surface of the adhesive layer. 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.
[0044]
Next, the process substrate is peeled off. 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.
[0045]
Necessary displays are printed on the sheet by a thermal transfer printer or the like, and a transparent plate such as an acrylic plate is attached to the printed surface via a transparent adhesive layer, and used as a display plate.
[0046]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The measurement methods used in the examples and comparative examples are as follows.
[0047]
(1) Surface roughness
Measured according to JIS B 0601.
[0048]
(2) Surface resistivity
JIS K
Measured according to 6911.
[0049]
(3) Coefficient of friction
Measured according to JIS K 7125.
[0050]
(4) Printable thermal transfer printer (made by KROY; model
K4250E) was used to print on the sheet, and the ink adhesion was visually confirmed. A sample with good printing was evaluated as ◯, and a sample in which a phenomenon such as ink not transferring or fading was observed was determined as X.
[0051]
(5) Antistatic atmosphere At 70 ° C for about 200 hours, stack sheets and apply a load (about 0.15 kg / cm2), peel the sheets one by one in a constant temperature and humidity chamber, The electrostatic voltage was measured using an electric machine (KS-525). 1 kV or less was judged as ◯, and above was judged as X.
[0052]
Example 1
A.
Acrylic resin “RS-3000” [trade name: manufactured by Nikka Polymer Co., Ltd.] 100 parts by weight, curing agent “Nikkarak MS-11” [trade name; manufactured by Sanwa Chemical Co., Ltd.] 18 parts by weight, cellulosic resin "CAB" [general name; manufactured by Special Colorant Industry Co., Ltd.] 15 parts by weight, UV absorber "Seasorb 103" [trade name; Sipro Kasei Co., Ltd.] 0.5 parts by weight, surface conditioner "BYK? 310" [ Product name: Big Chemie Japan Co., Ltd.] 0.16 parts by weight, catalyst “CT-198” [Product name: Special Colorant Industry Co., Ltd.] 0.03 parts by weight, MIBK 18.4 parts by weight, toluene 4.6 parts by weight Apply the blended solution onto Sandmat PET “PS-75” (trade name; manufactured by Teijin DuPont Films Ltd.) with a surface gloss (60 °) of about 4% to remove most of the solvent. A binder layer having a thickness of about 23 μm was formed. The viscosity at the time of coating the binder layer resin was 250 cP at room temperature.
[0053]
B.
On this binder layer, beads “UB-34NHAC” (trade name; manufactured by Union Co., Ltd.) with an average particle diameter of about 57 μm and a refractive index of about 2.2 are closely attached in a single layer, and heated to apply glass beads to the binder. It was embedded so that about 70% of the diameter was buried in the layer.
[0054]
100 parts by weight of acrylic resin “RS-5000” (trade name; manufactured by Nikka Polymer Co., Ltd.), 5.5 parts by weight of melamine crosslinking agent “Nicarac MS-11”, 15.7 parts by weight of MIBK, and 23.6 parts by weight of toluene are mixed by stirring. The blended solution was applied onto the binder layer and the glass beads to remove most of the solvent to form a transparent focal layer having a thickness of about 25 μm. The focal layer was formed in a shape along the spherical surface of the glass beads. Thereafter, aluminum was deposited on the focal layer to form a light reflecting layer having a thickness of about 0.3 μm.
Next, 100 parts by weight of adhesive resin “Nissetsu PE-115E” (trade name; manufactured by Nikka Polymer Co., Ltd.), 10 parts by weight of pigment “AR-9127 WHITE” (trade name; manufactured by Special Colorant Industries Co., Ltd.) , 0.6 parts by weight of the cross-linking agent “Coronate L” (trade name; manufactured by Nippon Polyurethane Industry Co., Ltd.) and 36.6 parts by weight of ethyl acetate were stirred and applied to a PET film. An adhesive layer of about 40 μm was formed.
Next, the retroreflective element layer and the adhesive layer produced by the procedures A to C were bonded together so that the light reflective layer was adhered to the adhesive layer.
Finally, the sand mat PET was peeled off to produce the retroreflective sheet of the present invention. The obtained retroreflective sheet satisfied the object of the present invention sufficiently as shown in Table 1.
[0055]
Example 2
The sand mat PET was changed to one having a surface gloss (60 °) of about 15% manufactured by Kaisei Kogyo, and a retroreflective sheet was prepared in the same manner as in Example 1.
[0056]
Example 3
A retroreflective sheet was prepared in the same manner as in Example 1 except that acrylic resin “RS-1200” (trade name; manufactured by Nikka Polymer Co., Ltd.) was used instead of RS-3000.
[0057]
Example 4
Polyester resin “P-647BC” (trade name; manufactured by Mitsui Chemicals, Inc.) 1 part by weight, polyester resin “Q-203” (trade name; manufactured by Mitsui Chemicals, Inc.) 100 parts by weight, cellulose resin “ 15 parts by weight of CAB (generic name; manufactured by Special Colorant Industries Co., Ltd.), 11.6 parts by weight of additive melamine-based crosslinking agent “Nicalak MS-11”, 32.63 parts by weight of MIBK, and 13.98 parts by weight of toluene were mixed with stirring. Apply the compounded liquid onto Sandmat PET “PS-75” (trade name; manufactured by Teijin DuPont Films Ltd.) with a surface gloss (60 °) of about 4%, and remove most of the solvent to obtain a thickness. About 13 μm of binder layer 1 was formed. The viscosity of the binder layer 1 when applied was 100 cP at room temperature.
[0058]
On this binder layer 1, 90 parts by weight of acrylic resin “RS-2000” [trade name; manufactured by Nikka Polymer Co., Ltd.], acrylic resin “ST-1014” [trade name; manufactured by Special Colorant Industries Co., Ltd.] ] Apply 10 parts by weight, 12 parts by weight of the melamine cross-linking agent “Nicarak MS-11”, 18.9 parts by weight of MIBK, and 28.35 parts by weight of toluene. A binder layer 2 having a thickness of about 10 μm was formed.
On binder layer 2, acrylic resin “RS-3000” [trade name; manufactured by Nikka Polymer Co., Ltd.] 100 parts by weight, isocyanate cross-linking agent “N-75” [trade name; manufactured by Sumitomo Bayer Urethane Co., Ltd.] A blended solution in which 12 parts by weight and 43.23 parts by weight of MIBK were mixed with stirring was applied, and most of the solvent was removed to form a binder layer having a thickness of about 46 μm in three layers. On this binder layer, beads “UB-34NHAC” (trade name; manufactured by Union Co., Ltd.) with an average particle diameter of about 57 μm and a refractive index of about 2.2 are closely attached in a single layer, and heated to apply glass beads to the binder. It was embedded so that about 70% of the diameter was buried in the layer.
[0059]
100 parts by weight of acrylic resin “RS-5000” (trade name; manufactured by Nikka Polymer Co., Ltd.), 5.5 parts by weight of melamine crosslinking agent “Nicarac MS-11”, 15.7 parts by weight of MIBK, and 23.6 parts by weight of toluene are mixed by stirring. The blended solution was applied onto the binder layer and the glass beads to remove most of the solvent to form a transparent focal layer having a thickness of about 25 μm. The focal layer was formed in a shape along the spherical surface of the glass beads. Thereafter, aluminum was deposited on the focal layer to form a light reflecting layer having a thickness of about 0.3 μm.
Next, adhesive resin “Nissetsu PE-115E” (trade name; manufactured by Nippon Carbide Industries Co., Ltd.) 100 parts by weight, pigment “AR-9127 WHITE” (trade name; manufactured by Special Colorant Industries Co., Ltd.) 10 Part by weight, 0.6 parts by weight of the cross-linking agent “Coronate L” (trade name; manufactured by Nippon Polyurethane Industry Co., Ltd.) and 36.6 parts by weight of ethyl acetate were stirred and applied to a PET film, and most of the solvent was removed. An adhesive layer having a thickness of about 40 μm was formed.
Next, the retroreflective element layer and the adhesive layer produced by the procedures I to M were bonded together so that the light reflective layer adhered to the adhesive layer.
Finally, the sand mat PET was peeled off to produce a retroreflective sheet.
[0060]
Comparative Example 1
The process substrate was changed from a sand matte PET film to a PET film “S-75” [trade name; manufactured by Teijin DuPont Films Ltd.], and a retroreflective sheet was prepared in the same manner as in Example 1.
[0061]
Comparative Example 2
0.73 parts by weight of the antistatic agent “Nopcostat 092” (trade name; manufactured by San Nopco Co., Ltd.) was added to the mixed solution of the Top layer 1 of Comparative Example 1, and a retroreflective sheet was formed in the same manner as in Comparative Example 1.
[0062]
Comparative Example 3
Polyethylene laminated paper “EKR-78UL” (trade name; manufactured by Lintec Co., Ltd.) with beads “UB-34NHAC” (trade name; manufactured by Union Co., Ltd.) having an average particle diameter of about 57 μm and a refractive index of about 2.2 in a single layer Adhering and applying heat, the glass beads were embedded in the binder layer so that about 20% of the diameter was embedded.
100 parts by weight of acrylic resin “RS-5000” (trade name; manufactured by Nikka Polymer Co., Ltd.), 5.5 parts by weight of melamine cross-linking agent “Nicarac MS-11”, 2.2 parts by weight of MIBK, and 3.3 parts by weight of toluene are stirred and mixed. The blended solution was applied onto the polyethylene reminate paper and glass beads to remove most of the solvent to form a transparent focal layer having a thickness of about 40 μm. The focal layer was formed in a shape along the spherical surface of the glass beads. Thereafter, aluminum was deposited on the focal layer to form a light reflecting layer having a thickness of about 0.3 μm.
Next, 100 parts by weight of adhesive resin “Nissetsu PE-115E” (trade name; manufactured by Nikka Polymer Co., Ltd.), 10 parts by weight of pigment “AR-9127 WHITE” (trade name; manufactured by Special Colorant Industries Co., Ltd.) , 0.6 parts by weight of the cross-linking agent “Coronate L” (trade name; manufactured by Nippon Polyurethane Industry Co., Ltd.) and 36.6 parts by weight of ethyl acetate were stirred and applied to a PET film. An adhesive layer of about 40 μm was formed.
Next, the retroreflective element layer and the adhesive layer prepared in the above procedure were bonded together so that the light reflecting layer was adhered to the adhesive layer.
Finally, the polyethylene laminated paper was peeled off to produce a retroreflective sheet.
[0063]
[Table 1]

[0064]
【The invention's effect】
The present invention provides a glass bead-encapsulated retroreflective sheet having a binder layer encapsulating glass beads and a focal layer positioned on the back side of the binder layer as a retroreflective element, and having an adhesive layer. By setting the thickness Ra to 0.1 to 1.0 μm, a retroreflective sheet for a display panel having an excellent antistatic effect is provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an encapsulated lens type retroreflective sheet which is an embodiment of the retroreflective sheet of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 .... Microsphere lens 2 ... Binder layer 3 ... Focus layer 4 ... Light reflection layer 5 ... Adhesive layer 6 ······Base material

Claims (3)

As a retroreflective element, a glass bead-encapsulated retroreflective sheet having a binder layer encapsulating glass beads and a focal layer located on the back side of the binder layer and having an adhesive layer has a surface roughness Ra of 0.1. binder layer by forming a binder layer on a process substrate in ~ 1.0 mu m is formed, the binder layer had a solids content of a viscosity at 25-50% is 80 ~ 400 cP at coating A retroreflective sheet comprising an acrylic resin and having a binder layer having a surface roughness Ra of 0.1 to 1.0 μm. The process for producing a retroreflective sheet according to claim 1, wherein the process substrate is a polyethylene terephthalate (PET) film. The process for producing a retroreflective sheet according to claim 2, wherein the process base material is a blasted polyethylene terephthalate (PET) film.

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