JP2012048229A - Retroreflective sheet and vehicle number plate with retroreflective sheet - Google Patents

Abstract

An object of the present invention is to provide a retroreflective sheet that is easy to remove after embossing and does not propagate tears to other than a marking part, and to provide a vehicle license plate using such a retroreflective sheet.
A retroreflective sheet (10) used for a vehicle license plate (50) in which a marking part is embossed and a retroreflective sheet on the upper part of the marking part is removed to expose a plate base (51). When measured in an environment of a temperature of 23 ° C. and a humidity of RH 65%, it has an elongation of 120% or less, has a breaking strength of 10 N / inch or more, and has a breaking strength higher than the adhesive strength to the plate substrate (51). Is large.
[Selection] Figure 4

Description

  The present invention relates to a retroreflective sheet and a license plate for vehicles such as automobiles and motorcycles using the same. More specifically, the present invention relates to a vehicle license plate in which the retroreflective sheet is an encapsulated lens type retroreflective sheet and the marking portion of the license plate is embossed.

  Conventionally, retroreflective sheets that reflect incident light toward a light source are well known and widely used in the field of license plates.

  As such a retroreflective sheet, an encapsulated lens type retroreflective sheet is well known in which a sheet having a minute glass sphere and a specular reflection layer obtained by vacuum-depositing an aluminum plate is used as a retroreflective element.

  An example of the encapsulated lens type retroreflective sheet is disclosed in detail in JP-A-59-71848 (Patent Document 1).

  Conventionally, such an encapsulated lens type retroreflective sheet is bonded to a base material such as an aluminum plate and an embossing is performed on the marking part, and then the encapsulated lens type retroreflective sheet of the marking part is removed, and the marking part is subjected to a roller coating method or the like. Vehicle license plates printed by the hot stamp method are known.

  However, this printing operation is troublesome, and another simple method has been demanded.

  As an alternative to printing, an encapsulated lens type retroreflective sheet, an aluminum foil sheet with an adhesive layer, and a coated plate are laminated in this order, and the marking part is embossed and then placed on the marking part. A vehicle license plate has been proposed in which the sheet and the aluminum foil sheet with the adhesive layer are removed, and the color of the painted plate is identified as a marking portion.

JP 59-71848 A

  However, when the emboss molding is performed, the encapsulated lens type retroreflective sheet disposed on the marking portion that is raised by the emboss molding and the encapsulated lens type retroreflective sheet disposed on a portion other than the marking portion are cut. May remain connected. In such a case, if the encapsulated lens type retroreflective sheet placed on the marking part is to be removed, the reflective sheet other than the marking part will be removed and the marking part of the vehicle license plate will be recognized as a result. It can be difficult to do.

  In addition, when removing the encapsulated lens type retroreflective sheet disposed on the marking portion, the encapsulated lens type retroreflective sheet may be broken during removal due to the force applied to the encapsulated lens type retroreflective sheet. In such a case, the entire encapsulated lens type retroreflective sheet placed on the marking portion cannot be removed, leaving behind, which may make it difficult to recognize the marking portion of the vehicle license plate. .

  The present invention has been made in consideration of the above points, and provides a retroreflective sheet that is easy to remove after embossing molding and does not propagate tears other than the marking part, and a vehicle number using such a retroreflective sheet. To provide a plate.

  A retroreflective sheet used for a vehicle license plate in which the marking part is embossed and the retroreflective sheet at the top of the marking part is removed and the plate base material is exposed, the retroreflective sheet having a temperature of 23 ° C., When measured in an environment with a humidity of RH 65%, it has an elongation of 120% or less, a breaking strength of 10 N / inch or more, and the breaking strength is larger than the adhesive strength to the plate base material. It is.

  According to the present invention, it is possible to provide a retroreflective sheet that is easy to remove after embossing and does not propagate tears other than the marking portion, and a vehicle license plate using such a retroreflective sheet.

It is sectional drawing explaining the structure of the retroreflection sheet which concerns on this embodiment. It is a figure explaining the number plate for vehicles concerning this embodiment. It is a figure which shows the mode of the VV cross section of FIG. It is a figure which shows a mode that the enclosure lens type retroreflection sheet was laminated | stacked on the plate base material one surface from the same viewpoint as FIG. It is a figure which shows the mode after embossing from the same viewpoint as FIG.

  Hereinafter, preferred embodiments of the retroreflective sheet according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the encapsulated lens-type retroreflective sheet (10) includes at least a surface protective layer (1), a holding layer (3) that holds a micro glass sphere (4), and a focal point of the micro glass sphere. It has a specular reflection layer (6) arranged at a position, a focus forming layer (5) for arranging the specular reflection layer at a focal position, and an adhesive layer (17). These layers are laminated in the order of the surface protective layer (1), the holding layer (3), the focus forming layer (5), the specular reflection layer (6), and the adhesive layer (17).

  In addition, when a light beam is emitted from a light source (not shown) toward the surface protective layer (1), the light beam is incident from the surface protective layer (1), and forms a focus with the holding layer (3), the glass sphere (4), and the like. Pass through layer (5). After passing, the incident light beam (incident light) is retroreflected by the specular reflection layer (6) in the direction of the light source through the same path X through which the incident light has passed.

  In this embodiment, a release improving layer (16) is disposed between the surface protective layer (1) and the holding layer (3). Further, a printing layer (2) for coloring the retroreflective sheet or identifying the production lot, product grade, etc. is disposed between the peel improving layer (16) and the holding layer (3). . In such an encapsulated lens type retroreflective sheet (10), in order to protect the adhesive layer (17) until the retroreflective sheet (10) is bonded to various substrates, the reflective sheet (10) A peelable release substrate (30) is provided on the adhesive layer (17).

  In addition, since each layer which comprises this enclosed lens type retroreflection sheet (10) can form the thickness precision of each layer, it is preferable to form by the solvent casting method.

  Further, this encapsulated lens type retroreflective sheet (10) has an elongation of at least 120% and a breaking strength of 10 N / inch or more when measured in an environment of a temperature of 23 ° C. and a humidity of RH 65%. The elongation and breaking strength of the encapsulated lens type retroreflective sheet (10) can be adjusted by changing the thickness, composition, etc. of the surface protective layer (1) and the adhesive layer (17), for example.

  The surface protective layer (1) is a layer that forms the surface of the retroreflective sheet, and is provided for the purpose of improving the durability and strength of the encapsulated lens type retroreflective sheet (10).

  The material of the surface protective layer (1) is not particularly limited, but usually a resin such as acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester resin, urethane resin, polycarbonate resin alone, Or they can be used in combination. Of these, acrylic resins, polyester resins, and vinyl chloride resins are preferably used from the viewpoint of weather resistance and processability, and acrylic resins and polyester resins are used in consideration of coating suitability and dispersibility of colorants when coloring. Is particularly preferred.

  The holding layer (3) is a layer for holding the micro glass sphere (4), and usually a resin such as an acrylic resin, an alkyd resin, a fluororesin, a vinyl chloride resin, a polyester resin, a urethane resin, or a polycarbonate resin alone. Or can be used in combination. From the viewpoint of weather resistance and workability, it is preferable to use an acrylic resin, a polyester resin, or a vinyl chloride resin, and it is particularly preferable to use an acrylic resin in consideration of coating suitability and dispersibility of a coloring agent when coloring.

  The specular reflection layer (6) is a layer for reflecting light, and usually means such as vacuum vapor deposition or sputtering using a metal such as aluminum, silver, chromium, nickel, magnesium, gold, tin or the like. In order to uniformly form a metal thin film reflecting the shape of the focus forming layer, a vapor deposition method is particularly preferable. The thickness of the specular reflection layer is 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, particularly preferably 0.08 to 0.12 μm.

  The focus forming layer (5) is a layer for disposing the specular reflection layer (6) at the focus position of the fine glass sphere (4), and is usually acrylic resin, alkyd resin, fluororesin, vinyl chloride resin, polyester. Resins such as resins, urethane resins, polycarbonate resins, and butyral resins can be used alone or in combination, but acrylic resins are preferably used from the viewpoint of weather resistance, coating suitability, and thermal stability.

  The peel improving layer (16) is for improving the peelability so that it can be peeled off from a plate base material such as a license plate without breaking the retroreflective sheet portion arranged on the marking portion raised by embossing. is there. The breaking strength in the peel improving layer (16) is greater than the adhesive strength of the adhesive layer (17) to the plate substrate.

  The material of such a peel improving layer (16) was formed of a resin such as an acrylic resin, an alkyd resin, a fluororesin, a vinyl chloride resin, a polyester resin, a urethane resin, a polycarbonate resin, or a butyral resin alone or in combination. It is preferable that it is a resin film from a viewpoint of peeling without breaking the retroreflective sheet | seat part arrange | positioned on a marking part.

  Among them, from the viewpoint of peeling without breaking the retroreflective sheet portion disposed on the marking portion, it is a resin formed by combining resins such as acrylic resin, polyester resin, vinyl chloride resin alone or in combination. preferable.

  The adhesive layer (17) is a layer for adhering the retroreflective sheet to various substrates such as a plate substrate, and the types of resins forming the adhesive layer are, for example, acrylic resins, silicone resins, rubber resins, A phenol resin or the like is used. Of these, acrylic resins or silicone resins having excellent weather resistance and good adhesive properties are preferably used. In addition, it is preferable to make the adhesive force in an adhesive bond layer (17) small from a viewpoint of peeling off an encapsulated lens type retroreflection sheet (10) easily. The adhesive strength of the adhesive layer (17) is reduced by adjusting the resin type, molecular weight and functional group amount of the resin composition contained in the adhesive layer, adding a plasticizer, or adjusting the amount of the crosslinking agent. can do. Moreover, the adhesive force can also be reduced by reducing the thickness of the adhesive layer (17).

  Such an encapsulated lens type retroreflective sheet (10) is manufactured by the method described below, for example. First, the surface protective layer (1) is obtained by coating and drying a resin compounded solution for the surface protective layer on a film-like process substrate.

  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 polyethylene terephthalate (PET), polyimide, vinyl chloride, or the like. A substrate can be used, and among them, PET is particularly preferable. Further, the coating method of the resin compounding solution is not particularly limited as long as it can be uniformly applied at a predetermined thickness, but a method such as a reverse roll coating method or a comma direct coating method is preferably used. It is done.

  Next, on the surface protective layer (1), after applying the resin compounding liquid for peeling improvement layers, it dries and obtains a peeling improvement layer (16).

  Next, a resin compound liquid for the holding layer is applied on the release improving layer (16) and semi-dried. Next, fine glass spheres are sprayed on the semi-dried holding layer and subjected to heat treatment. In this way, a retention layer (3) is obtained. The embedding rate of embedding the micro glass spheres in the retaining layer can be adjusted by the degree of semi-drying of the retaining layer.

  Next, the resin composition solution for the focus forming layer is applied to the surface of the fine glass sphere. The coating method is not particularly limited as long as it can be uniformly applied with a predetermined thickness, but a method such as a reverse roll coating method or a comma direct coating method is preferably used.

  This resin composition solution for the focus forming layer is applied at room temperature, and heat-treated as necessary to cure the resin. In this way, a focus formation layer (5) is obtained. The curing temperature varies depending on the type of resin / curing agent, but when an acrylic resin is used as the focus-forming layer resin, it is preferably heated to 50 to 160 ° C., preferably 70 to 155 ° C. for 3 to 10 minutes.

  Next, a metal thin film is formed on the focus formation layer to form a specular reflection layer (6). As a method for forming the metal thin film, a coating method, a vacuum vapor deposition method, or the like can be used. However, in order to uniformly form a metal thin film reflecting the shape of the focus forming layer, the vapor deposition method is particularly preferable. The thickness of the metal thin film is 0.05 μm to 0.2 μm, preferably 0.05 μm to 0.15 μm, particularly preferably 0.08 to 0.12 μm.

  Conditions such as the vapor deposition rate, temperature, and vacuum degree may be selected as appropriate according to the equipment, and the metal thin film may have a uniform thickness.

  Next, a resin compounding solution for forming an adhesive layer is separately applied and dried on the release substrate (30) to obtain an adhesive layer (17). And the specular reflection layer (6) produced as mentioned above and an adhesive bond layer (17) are bonded together. 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 heat of, for example, about 50 to 90 ° C.

  Finally, the process substrate is peeled off to obtain an encapsulated lens type retroreflective sheet (10) as shown in FIG.

  Next, the vehicle license plate according to this embodiment using the encapsulated lens type retroreflective sheet (10) will be described.

  As shown in FIG. 2, the vehicle license plate (50) has a structure in which an encapsulated lens type retroreflective sheet (10) is laminated on one surface of a plate substrate (51). The plate substrate (51) is a colored painted plate, a laminated metal plate to which a colored film is attached, an electrolytically colored metal plate, a dyed plate, or the like.

  On one surface of such a vehicle license plate (50), the marking portion is raised by embossing. Moreover, as shown in FIG. 3 which is a VV cross section of FIG. 2, the encapsulated lens type retroreflective sheet (10) arranged on the marking portion raised by the emboss molding is peeled off.

  Such a vehicle license plate (50) is manufactured, for example, by the method described below. First, the peeling base material (30) laminated | stacked on the encapsulation lens type retroreflection sheet (10) is peeled, and the adhesive layer (17) of the encapsulation lens type retroreflection sheet (10) is exposed.

  Next, as shown in FIG. 4, an encapsulated lens-type retroreflective sheet (10) is attached to one surface of the plate substrate (51) via the adhesive layer (17), and the plate intermediate (50X). Get.

  As described above, the encapsulated lens type retroreflective sheet (10) has an overall sheet elongation of 120% or less and a breaking strength of 10 N / inch or more in an environment of a temperature of 23 ° C. and a humidity of RH 65%. Therefore, even if one surface of the plate substrate (51) is flat, it is possible to prevent wrinkles or cracks when the encapsulating lens type retroreflective sheet (10) is pasted.

  Next, the plate intermediate (50X) is embossed. Specifically, the protective layer (11) of the plate intermediate body (50X) faces the concave surface of the concave mold, and the plate base material (51) of the plate intermediate body (50X) faces the convex surface of the convex mold. In this state, the plate intermediate (50X) is disposed between the concave mold and the convex mold. Then, the concave mold and the convex mold are clamped, and by this clamping, as shown in FIG. 5, the concave mold (61) and the convex mold (62) are arranged. A part of the plate intermediate (50X) is raised as an indicator.

  As described above, the encapsulated lens type retroreflective sheet (10) has an overall sheet elongation of 120% or less and a breaking strength of 10 N / inch or more in an environment of a temperature of 23 ° C. and a humidity of RH 65%. Accordingly, as long as the clamping pressure between the concave mold (61) and the convex mold (62) is within a generally adopted range, as shown in FIG. 5, retroreflective disposed on the marking portion. It is possible to prevent the sheet part and the other retroreflective sheet part from being cut and connected. Moreover, it is possible to prevent wrinkles and wrinkles from being formed or cracked in the retroreflective sheet portion disposed on the marking portion or other retroreflective sheet portions due to the cutting.

  Finally, using a predetermined jig, the retroreflective sheet portion disposed on the marking portion is peeled off at a constant tension and speed.

  As described above, the breaking strength of the peel improving layer (16) is greater than the adhesive strength of the adhesive layer (17) to the plate base material (51). Therefore, it can peel without breaking the retroreflective sheet | seat site | part arrange | positioned on a marking part. In addition, since the encapsulated lens-type reflective sheet placed on the marking portion is not left behind, it is possible to avoid the work of peeling off the encapsulated lens-type reflective sheet on the marking portion over and over, thereby improving work efficiency. Can be improved.

  Thus, the vehicle license plate (50) as shown in FIG. 2 can be obtained.

  The marking part is a part for marking information on the license plate, which is composed of a combination of letters, numbers, symbols, symbols, and the like.

  As mentioned above, although the said embodiment was demonstrated as an example of this invention, this invention is not limited to the said embodiment.

  For example, in the said embodiment, the peeling improvement layer (16) in the enclosure lens type retroreflection sheet (10) was arrange | positioned between the surface protective layer (1) and the holding layer (3). However, the arrangement position of the peel improving layer (16) is not limited to the above embodiment. For example, it is arranged on the light incident side of the surface protective layer (1), between the surface protective layer (1) and the holding layer (3), or between the specular reflection layer (6) and the adhesive layer (17). be able to. In addition, when providing a peeling improvement layer (16) on the surface protective layer (1) or between the surface protective layer (1) and the holding layer (3), the retroreflection performance is not impaired. Requires transparency.

  Hereinafter, it demonstrates in detail using an Example.

<Example 1>
First, a white encapsulated lens type retroreflective sheet was produced as follows.

  Polyester resin solution (trade name, HMP90S) manufactured by Mitsui Chemicals, polyester resin solution (trade name, Q-203) manufactured by Mitsui Chemicals, and polyester resin solution (trade name, P-110) manufactured by Mitsui Chemicals, Inc. : To 100 parts by mass of the mixed solution mixed at a mass ratio of 4: 1, 11 parts by mass of the methylated melamine resin solution (trade name, Nicarak MS-11) manufactured by Sanwa Chemical Co., Ltd. (Product name, CAB) 10 parts by mass, 0.5% by mass of UV absorber (trade name, Seasoap 103) manufactured by Sipro Kasei Co., Ltd. 50% MIBK of UV absorber (trade name, TINUVIN 213) manufactured by BASF Japan Ltd. 0.6 parts by mass of solution, 0.05 quality of leveling agent (trade name, BYK-300) manufactured by Big Chemie Japan Co., Ltd. Part, 0.12 parts by mass of a catalyst manufactured by DIC Corporation (trade name, Beccamin P-198), 9.2 parts by mass of MIBK as a solvent, and 9.2 parts by mass of toluene, and stirring and mixing the resin for forming a surface protective layer A blended solution was obtained.

  Using a transparent polyethylene terephthalate film (trade name, Teijin Tetron Film S-75) made by Teijin Limited as the process substrate, coating and drying the resin composition for forming the surface protective layer thereon, and then thickening A colorless and transparent surface protective layer having a thickness of about 26 μm was formed.

  Subsequently, 100 parts by mass of the acrylic resin solution (trade name, RS-1200) manufactured by Onuki Aika Kogyo Co., Ltd. and 16. methylated melamine resin solution (trade name, Nicalac MS-11) manufactured by Sanwa Chemical Co., Ltd. 7 parts by mass of Tokushi Co., Ltd. cellulose derivative (trade name, CAB) 6 parts by mass, Sipro Kasei Co., Ltd. benzophenone UV absorber (trade name, Seasorb 103) 1.5 parts by mass, manufactured by Big Chemie Japan Co., Ltd. 0.04 parts by mass of a leveling agent (trade name, BYK-300), 6.2 parts by mass of MIBK as a solvent and 9.3 parts by mass of toluene were added, and a resin compounded liquid for forming a peel improving layer was obtained by stirring and mixing.

  On the surface protective layer, the release improving layer forming resin blend solution was applied and dried to form a colorless and transparent release improving layer having a thickness of about 20 μm.

  Next, 100 parts by mass of acrylic resin (trade name RS-3000) manufactured by Onukiai Co., Ltd., 1 part by mass of isocyanate-based crosslinking agent (trade name, Sumidur N-75) manufactured by Sumika Bayer Urethane Co., Ltd., Asahi Kasei Corporation 11 parts by mass of an isocyanate-based crosslinking agent (trade name, Duranate D201), 28.2 parts by mass of toluene as a solvent, and 42.3 parts by mass of MIBK were mixed and stirred to obtain a resin composition for forming a holding layer.

  On the peel improving layer, the holding layer forming resin compounded liquid was applied on the surface protective layer and dried at 70 ° C. for 5 minutes to obtain a holding layer having a thickness of about 18.5 μm.

  Micro glass spheres (NB-12) manufactured by Onuki Ai Co., Ltd. having an average particle size of 53 μm were adhered to this holding layer, and heat treatment was performed to submerge the micro glass spheres in the holding layer. When the cross section was observed with a microscope, the fine glass sphere was in contact with the holding layer, and approximately 60% of the diameter of the fine glass sphere was embedded in the holding layer.

  Next, 100 parts by mass of an acrylic resin solution (trade name, RS-5000) manufactured by Enki Aika Chemical Co., Ltd., and 5.5 masses of a methylated melamine resin solution (trade name, Nicalac MS-11) manufactured by Sanwa Chemical Co., Ltd. As a part and a solvent, 15.7 parts by mass of MIBK and 23.6 parts by mass of toluene were added, and a resin composition liquid for forming a focal layer was obtained by stirring and mixing.

  The focal layer-forming resin compounded solution was applied and dried on the holding layer and the fine glass spheres to form a focal-forming layer having an average thickness of about 23 μm.

  Subsequently, aluminum was vacuum-deposited on the focus forming layer to obtain a specular reflection layer. Hereinafter, it is referred to as an intermediate product.

  Separately, a release paper manufactured by Lintec Corporation (trade name, EN11PM (31) -CM-P) was used as a release substrate, and a 2EHA / MA copolymer (mass ratio: 2EHA / MA = 50 / 50) ethyl acetate / toluene (1/1) solution (solid content: 41%) 100 parts by mass, Sumika Bayer Urethane Co., Ltd. isocyanate cross-linking agent (trade name, Sumidur N-75) 0.3 parts by mass Then, 8 parts by mass of ethyl acetate was added as a solvent, and the mixed resin composition for forming an adhesive layer was applied and dried to form an adhesive layer having a thickness of about 40 μm.

  Lamination was performed so that the mirror reflection layer of the intermediate product and the adhesive layer were in contact with each other, and the polyethylene terephthalate film as the process substrate was peeled off to obtain a retroreflective sheet.

  The elongation of the obtained retroreflective sheet was 94.1%, the breaking strength was 26.4 / inch, and the adhesive strength to the plate substrate used in Example 1 was 7.8 N / inch.

  Next, using the retroreflective sheet produced above, a vehicle license plate was produced according to the following procedure.

  First, an aluminum substrate with a thickness of 0.9 mm and a size of 520 mm × 113 mm coated with a 40 μm-thick blue-violet paint (Beckers product name Beckrypol 350) as a plate substrate (product name aluminum plate made by HULAMIN) The retroreflective sheet 1 was attached to the paint surface at a pressure of 1 kgf / cm using a rubber roll having a diameter of 40 mm and a length of 100 mm.

  The plate base material on which the retroreflective sheet 1 is laminated is recursively formed between an embossing mold (lower mold) and a concave mold (upper mold) in an embossing apparatus (SUPLEME HYDRAULIC MACHINE manufactured by UNIPLATE). The reflective sheet was set with the concave side. Four types of characters “B”, “D”, “F”, and “4” were used, and the size of the characters was 75 mm long and 34 mm wide.

  The embossing was performed at an indoor environment temperature of 23 ° C. and a pressure of 50 kgf / m 2 and an emboss height of 2 mm at an embossing speed of 1 second.

  By the embossing of this embossing apparatus, the retroreflective sheet was cut into the shape of the letters on the license plate.

  The marking part of the cut retroreflective sheet is a jig whose front end is cut at an inclination of 30 degrees, and an unnecessary retroreflective sheet is placed from the end part of the character, and the retroreflective sheet is approximately 10 N approximately upward. It was removed at a speed of 300 mm / min with a tension of / m.

  The retroreflective sheet on the marking part of the license plate was removed, the plate base material was exposed, the marking part was bluish purple, and the peripheral part of the marking was white and the vehicle license plate was retroreflected.

  The retroreflective sheet used for the obtained vehicle license plate is free from wrinkles and peeling, and can be cut cleanly according to the shape of the marking part when embossing. It was easy to remove, and no tears propagated to the necessary parts.

  In addition, when the obtained vehicle license plate was mounted on a vehicle and exposed outdoors for half a year, the retroreflective sheeting around the marking did not peel off or tear, and the information on the license plate was displayed in the same manner as when mounted on the vehicle. Was visually confirmed.

  In addition, the adhesive force in an Example was measured as follows. That is, the retroreflective sheet of the present invention is cut to 1 inch width, and the peeling substrate at the end of the cut retroreflective sheet is peeled off. Then, a retroreflective sheet was applied to the painted surface of the aluminum plate manufactured by HULAMIN at a room environment temperature of 23 ° C. under a pressure of 1 kgf / cm and left for 24 hours. After leaving, the aluminum plate was fixed, and the end portion of the retroreflective sheet on which the base material was not attached was peeled off at 180 ° using Tensilon manufactured by Shimadzu Corporation to determine the adhesive strength. The measurement was performed three times, and the average value was taken as the adhesive strength.

  Further, the elongation in the examples was measured as follows. That is, in accordance with JIS Z9117, a test piece having a width of 25 mm and a length of 300 mm was set at a gripping interval of 100 mm, and was pulled and stretched under a condition of 300 mm / min using Tensilon manufactured by Shimadzu Corporation.

  Moreover, the breaking strength in an Example was measured as follows. That is, in the measurement of the elongation, the strength value at which the test piece breaks was determined. The measurement was performed three times, and the average value was taken as the breaking strength.

<Example 2>
Tokiki's acrylic resin solution (trade name, ST-100) is 100 parts by mass, and methylated melamine resin solution (trade name, Nicarak MS-11) manufactured by Sanwa Chemical Co., Ltd. is 16 parts by mass. 6 parts by weight of cellulose derivative (trade name, CAB), 1.5 parts by weight of benzophenone ultraviolet absorber (trade name, Seasorb 103) manufactured by Sipro Kasei Co., Ltd., leveling agent (trade name, BYK-) manufactured by Big Chemie Japan Co., Ltd. 300) was added by 0.05 parts by mass, DIC Corporation catalyst (trade name, Beccamin P-198) was added by 0.12 parts by mass, MIBK 9.2 parts by mass and toluene 9.2 parts by mass were added, and the mixture was stirred. An acrylic resin layer forming resin blend solution 1 was obtained.

  A transparent polyethylene terephthalate film (trade name, Teijin Tetron Film S-75) made by Teijin Ltd. is used as a process substrate, and a resin compounding solution for forming an acrylic resin layer is coated and dried on the film. A colorless and transparent acrylic resin layer having a thickness of about 30 μm was formed.

  Next, 86 parts by mass of Tokiki acrylic resin solution (trade name, ST3105), 1.0 parts by mass of benzophenone ultraviolet absorber (trade name, Seasorb 103) manufactured by Sipro Kasei Co., Ltd., Sumika Bayer Urethane Co., Ltd. 13 parts by mass of an isocyanate-based cross-linking agent (trade name, Sumidur N-75) and 10 parts by mass of MIBK as a solvent were added, and a resin blend liquid 2 for forming an acrylic resin layer was obtained by stirring and mixing.

  On the colorless and transparent acrylic resin layer, the resin composition liquid 2 for forming an acrylic resin layer was applied and dried to form a layer having a thickness of about 25 μm. Thus, an acrylic resin film in which two acrylic resin layers were laminated was obtained.

  Separately, a release paper manufactured by Lintec Corporation (trade name, EN11PM (31) -CM-P) was used as a release substrate, and a BA / AA copolymer (mass ratio: BA / AA = 90 / 10) 100 parts by mass of ethyl acetate / toluene (1/1) solution (solid content 34%), 0.025 parts by mass of an epoxy-based crosslinking agent (trade name, Tetrad-C) manufactured by Mitsubishi Gas Chemical Co., Ltd. as a solvent 17.8 parts by mass of ethyl acetate was added, and the resin composition liquid for forming an adhesive layer, which was mixed by stirring, was applied and dried to form an adhesive layer having a thickness of about 35 μm.

  The adhesive layer was bonded to the previously produced acrylic resin film, and the process substrate was peeled off to obtain an acrylic resin film with an adhesive layer.

  The obtained acrylic resin film with an adhesive layer was laminated on the surface protective layer of a commercially available retroreflective sheet (trade name, manufactured by Enkiai (Hangzhou) Chemical Co., Ltd., T4412) as a peel improving layer, and was manufactured first. A retroreflective sheet 2 having an acrylic resin film as a peel improving layer was obtained.

  The elongation of the retroreflective sheet 2 was 55.7%, the breaking strength was 21.5 N / inch, and the adhesive force to the laminated substrate used in Example 1 was 18.0 N / inch.

  Using the retroreflective sheet 2 instead of the retroreflective sheet of Example 1, a vehicle license plate was obtained in the same manner as in Example 1.

  The retroreflective sheet used in the obtained vehicle license plate can be cut cleanly according to the shape of the marking part during embossing, and the unnecessary retroreflective sheet on the marking part can be easily removed. There was no propagation of tears.

  In addition, when the obtained vehicle license plate was mounted on a vehicle and exposed outdoors for half a year, the retroreflective sheeting around the marking did not peel off or tear, and the information on the license plate was displayed in the same manner as when mounted on the vehicle. Was visually confirmed.

  As described above, when measured in an environment of a temperature of 23 ° C. and a humidity of RH 65%, it has an elongation of 120% or less, has a breaking strength of 10 N / inch or more, and has a breaking strength higher than the adhesive strength to the plate substrate. By using a retroreflective sheet characterized by being large, it is easy to remove after embossing molding, and to provide a retroreflective sheet that does not propagate tears other than the marking part, and a vehicle license plate using such a retroreflective sheet Could be provided.

DESCRIPTION OF SYMBOLS 1 ... Surface protective layer 2 ... Print layer 3 ... Holding layer 4 ... Micro glass sphere 5 ... Focus formation layer 6 ... Specular reflection layer 16 ... Peeling improvement layer 17 ... -Adhesive layer 30 ... peeling substrate X ... light path 50 during retroreflection ... vehicle license plate 50X ... plate intermediate 51 ... plate substrate 61 ... concave side Mold 62 ... Convex mold

Claims (5)

A retroreflective sheet used in a vehicle license plate in which the marking part is embossed, the retroreflective sheet at the top of the marking part is removed, and the plate base material is exposed,
The retroreflective sheet is
When measured in an environment of a temperature of 23 ° C. and a humidity of RH 65%, it has an elongation of 120% or less, a breaking strength of 10 N / inch or more, and the breaking strength is larger than the adhesive strength to the plate substrate. Characteristic retroreflective sheet. The retroreflective sheet according to claim 1, wherein the retroreflective sheet is an encapsulated lens type retroreflective sheet.   A vehicle license plate using the retroreflective sheet according to claim 1. The vehicle number plate according to claim 3, wherein the plate base material is a metal plate. 5. The vehicle license plate according to claim 4, wherein the metal plate is any one of a colored coating plate, a laminated metal plate to which a colored film is attached, an electrolytic coloring plate, and a dyeing plate.

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