JP2005254643A - Optical functional film, article, method for manufacturing optical functional film and method for coating article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for giving a function as an optical functional film for judging the truth without spoiling a low-cost nature in a packaging technology using a heat-shrinkable film. <P>SOLUTION: An optical functional film 101 which is a laminate of two kinds of films with optical transmission properties and different refractive indexes, and is capable of tightly sticking on a substrate by heat shrinking properties and having discriminating properties by a blue shift by utilizing the heat shrinking properties exhibited by a multilayered thin film layer 104 which undergoes drawing processing and the blue shift phenomenon exhibited by the multilayered thin film layer 104, is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for identifying the authenticity (authenticity) of an article by a visual effect, and relates to an optical functional film having an authenticity identification function suitable for covering or attaching to an article for use. .

  In a cylindrical article such as a dry battery, a method of using a heat shrink film (shrink film) is known as a technique for applying a product logo, a cautionary note, or decoration on the surface of the article.

  In this method, arbitrary printing is performed on a film that shrinks when heat is applied, the film is wound around a cylindrical article, and the film is shrunk by applying heat, and the film is adhered to the article. In this method, a predetermined display content may be printed on the heat-shrink film, so that it is easy to cope with various display contents. Moreover, since it is only necessary to cover the article and then heat shrink, it is suitable for low cost and mass production. In addition, it is possible to easily cope with differences in the shape and size of articles. Because of such advantages, it is widely used for packaging of various packages and PET bottles filled with drinking water. This technique is described in Patent Document 1, for example.

  On the other hand, in many articles such as daily necessities and electrical appliances, fake products that look like real items appear on the market and become a problem. Under such circumstances, there is a need for a technology that can identify the authenticity of an article in order to guarantee performance, reliability, safety, or maintain brand power.

  As a technique for identifying the authenticity of an article, a method of performing printing using special ink on the article, or a method of attaching a small piece having special optical reflection characteristics to the article is known.

  As a method of applying special ink, the authenticity is confirmed by printing a predetermined character or design using ink that fluoresces against ultraviolet light, and then highlighting the design or character when irradiated with ultraviolet light. There is a way to do it. In addition, a method is known in which authenticity is identified by a magnetic sensor by applying ink mixed with magnetic particles or magnetic particles.

  As small pieces having optical reflection characteristics, those utilizing optical characteristics exhibited by cholesteric liquid crystals are known. This technique is disclosed in Patent Document 2, for example.

JP-A-6-210730 JP-A-4-14496

  Even in the packaging technology using the heat-shrinkable film described above, it is required to have a function capable of determining whether or not it is a counterfeit product. However, it has been difficult to provide an authenticity determination function without losing the superiority of the technology using the heat shrink film described above.

  For example, a method of printing a heat-shrinkable film with a special ink and imparting an authenticity identification function can be considered. However, such special ink is expensive and cannot take advantage of the superiority of the technology using a heat shrink film that is low cost. Also, it is relatively easy to obtain and abuse the ink, and its ability to prevent counterfeiting is not so high.

  A method using an optical functional film using cholesteric liquid crystal is also conceivable. However, an optical functional film using cholesteric liquid crystal must be prepared separately, which also increases the cost. In particular, cholesteric liquid crystals are disadvantageous in terms of cost in order to be used for inexpensive products that are mass-produced. Further, there is a problem that is fundamentally difficult to solve because the cholesteric liquid crystal does not exhibit a predetermined optical function due to the influence of heat shrinkage.

  An object of the present invention is to provide a technique that can provide a function as an optical functional film for authenticity determination without impairing low cost in a packaging technique using a heat shrinkable film.

  The optical functional film of the present invention is characterized in that it has a laminated structure in which light transmissive films having different refractive indexes are laminated in multiple layers, and has heat shrinkability for packaging an article by heat shrinkage.

  The heat shrinkability of packaging an article by heat shrinkage is a function of covering the article in a state before the heat shrinkage occurs and then heating it to heat shrink along the shape of the article and adhere to the article. Say. Therefore, it cannot be said that it has the heat shrinkability which wraps articles | goods by heat contraction only by shrinking only by heating. Here, the concept of packaging includes a state of packaging completely covering the entire article and a state of packaging covering a part of the article.

  Next, the optical properties of the laminated structure in which light transmissive thin film films having different refractive indexes are laminated in a multilayer manner will be described. FIG. 8 is a conceptual diagram showing a light reflection state in the multilayer thin film layer. In FIG. 8, light transmissive thin film films 801 (A layer) having a first refractive index and light transmissive thin film films 802 (B layer) having a second refractive index are alternately laminated in multiple layers. An example of a multilayer thin film layer 803 is shown.

  When white light is applied to the multilayer thin film layer 803, light is reflected at the interface between the layers in accordance with Fresnel's reflection law. That is, a part of the incident light is reflected at the interface between the A layer and the B layer, and the other is transmitted. The reason why a part of the incident light is reflected at the interface between the A layer and the B layer is that the refractive index of the A layer and the refractive index of the B layer are different.

  Since the interface between the A layer and the B layer appears repeatedly, reflected light generated at each interface interferes. When the incident angle of incident light is gradually increased, the optical path difference of the reflected light generated at each interface gradually decreases, and light of shorter wavelengths interferes and strengthens each other. Therefore, as the multilayer thin film film layer 803 that is exposed to white light is viewed more obliquely (an angle close to the plane), it appears that light having a shorter wavelength is more strongly reflected. For example, when the multilayer thin film layer 803 that is exposed to white light is tilted, the reflected light gradually appears bluish. This phenomenon is called blue shift. The incident angle is defined as an angle formed by a perpendicular to the incident surface and the optical axis of the incident light.

  The structure in which light transmissive thin film films having different refractive indexes are laminated in multiple layers means that at least two kinds of light transmissive thin film films having different refractive indexes are laminated, and the interface between the light transmissive thin film films having different refractive indexes is This refers to a multi-layer structure in which at least one exists. As a specific structure of the multilayer thin film, a structure in which two types of light-transmitting thin film films having different refractive indexes are alternately stacked in a multilayer structure, and a first to Nth (N is a natural number) refractive index. The structure etc. which laminated | stacked the 1st-Nth light transmissive thin film film in order as 1 unit as what was laminated | stacked by the arbitrary number are mentioned.

  The article covered with the optical functional film of the present invention is not limited at all. Examples of such articles include dry batteries, various daily necessities, foodstuffs, merchandise packages, electrical appliances, office supplies, electronic parts, and the like. In addition, passports, documents, various cards, passes, banknotes, vouchers, securities, certificates, gift certificates, pictures, tickets, public competition voting tickets, music and video recording media, computer software, where authentication is important The recording medium on which is recorded, their various products, their packages and the like can also be cited as articles in the present invention.

  The optical functional film of the present invention can be packaged by the same handling as a conventional heat-shrinkable film. Therefore, the facilities that have been used so far can be used, and the cost increase in the packaging work can be suppressed. Further, the optical functional film itself does not require a special material, and does not lead to a large cost increase.

  The appearance of the blue shift can be easily controlled by adjusting the stretching conditions for the laminated structure.

  Therefore, it is possible to provide a packaging material having heat shrinkability that can be used for packaging an article and an optical function for authenticity determination without causing an increase in cost.

  The blue shift exhibited by the optical functional film of the present invention is complicatedly related to the material, thickness, refractive index difference, and refractive index anisotropy of each optical film constituting the laminated structure. Further, the laminated structure is integrated by being stretched, and it is impossible to peel off a single layer. Therefore, even if the finished product is analyzed, it is extremely difficult to reproduce similar optical properties. For this reason, forgery is difficult, and it is suitable for authenticity determination means.

  In addition, since the optical functional film of the present invention is thermally shrunk in accordance with the shape of the article (base material) to be packaged, when viewing the packaged article, the blue shift is made to the curved surface portion without moving the viewing angle. A gradation change like a rainbow appears. The appearance of the curved surface portion depends on the shape of the article and is unique.

  The laminated structure in the optical functional film of the present invention is imparted with heat shrinkability by the stretching treatment and is adjusted. Further, when a polymer resin material such as PET or acrylic is used as the material for the light transmissive film, the refractive index of the film also changes due to the stretching treatment. By utilizing this fact, the heat shrinkability and the optical function (blue shift function) exhibited by the optical functional film can be simultaneously adjusted by the stretching process.

  For example, when the film is uniaxially stretched, the refractive index and the heat shrinkability in the stretched direction change simultaneously. Note that the refractive index in the stretched direction refers to the refractive index of the film with respect to linearly polarized light polarized in that direction. Moreover, when biaxial stretching is applied to the film, the heat shrinkability and the refractive index in the two-dimensional direction in the film plane can be adjusted.

  In this biaxial stretching, anisotropy can be imparted to the heat shrinkability and the refractive index by intentionally changing the stretched state in two orthogonal directions. That is, when anisotropy is imparted in the direction of heat shrinkage, the refractive index can also be adjusted to exhibit anisotropy in the plane. By utilizing this, a packaging structure is obtained that is adjusted so that thermal contraction according to the shape of the article occurs, and in which the article is wrapped, the blue shift state varies depending on the viewing direction. Can do.

  Thus, in the optical functional film of the present invention, the stretching treatment is uniaxial stretching, and it is preferable that the heat shrinkability in the direction in which the uniaxial stretching is performed is controlled. In this case, the heat shrinkability and the blue shift state in the stretched direction can be controlled by the stretching conditions.

  In the present invention, biaxial stretching may be performed as the stretching process. In this case, the contraction and the blue shift state in the two-dimensional plane can be controlled. For example, control of heat shrinkability by intentionally changing the heat shrinkage rate in the X-axis direction and the Y-axis direction perpendicular to the X-axis direction, and further intentional appearance of the blue shift in the X-axis direction and the Y-axis direction perpendicular thereto Control of the different optical characteristics can be realized by adjusting the stretching condition of biaxial stretching.

  The optical functional film of the present invention can observe a color change toward the curved direction of the curved surface in a state along the curved surface shape. That is, in a state where the optical functional element of the present invention is curved along a curved surface, when a predetermined curved surface portion is viewed from the vertical direction, a portion slightly deviated from the gaze portion (that is, a portion slightly moved in the curved direction of the curved surface) ) Is visually recognized from a direction having a viewing angle such that a blue shift appears due to the nature of the curved surface. As a result, it is possible to observe a color gradation in which a color change in the short wavelength direction continuously occurs as the distance from the gaze portion increases.

  Such a unique optical property also occurs when the optical functional film is thermally contracted and deformed along the shape of the substrate.

  In the optical functional film of the present invention, it is preferable to control the heat shrinkability by preliminarily applying a heat setting treatment in which heating is performed in a state where shrinkage cannot be performed. For example, if heating is performed in a state where surface pressure is applied so as not to shrink, thermal shrinkage does not occur, but the molecular structure changes, and thermal shrinkage when heated later is suppressed. If this phenomenon is utilized, it is possible to control in advance how much heat shrinkage is performed in the heat shrink process. This heat treatment performed in advance is called heat setting treatment.

  The optical functional film of the present invention preferably includes a light absorption layer. Since the blue shift uses interference of reflected light from a plurality of interfaces in the multilayer structure, it is necessary to prevent light other than the reflected light from the interfaces from being reflected as much as possible. This is advantageous in increasing the N ratio.

  The light absorption layer is disposed on the surface opposite to the observation surface side. The light absorption layer preferably has a black or dark color and has a function of absorbing light in a visible light band as wide as possible. Examples of the light absorbing layer include a resin layer in which carbon particles and the like are dispersed, a film having a dark color such as black, a layer formed by applying a dark color paint such as black, and the like.

  In the optical functional film of the present invention, it is preferable that hologram processing is applied to at least a part of the laminated structure. According to this aspect, in addition to the blue shift, an identification function based on the hologram effect can be obtained. Hologram processing can be obtained by embossing or uneven processing at least a part of the laminated structure.

  As a method of adding a hologram function, a hologram processing layer subjected to hologram processing may be provided. Since the hologram needs to be embossed or concavo-convex on the layer itself, it may be difficult to impart an effective structure depending on the material used. In particular, the present invention needs to give priority to the blue shift and heat shrinkability exhibited by the multilayer thin film, and therefore needs to be considered even if it is not suitable for hologram processing. In such a case, a layer suitable for performing hologram processing may be added to the laminated structure, and hologram processing may be performed on this layer. In this way, the function of the hologram can be pursued without sacrificing blue shift and heat shrinkability.

  The heat shrinkability exhibited by the optical functional film of the present invention is preferably such that the shrinkage ratio when heated is 25% or more in terms of dimensional ratio. When the shrinkage ratio is less than 25% in terms of the dimensional ratio, the followability and adhesion to the shape of the article are insufficient, which is not preferable as a packaging material. The shrinkage rate in terms of the size ratio is calculated as ((A−B) / A) × 100, where A is the size before shrinkage and B is the size after shrinkage.

  This invention can also be grasped | ascertained as an article | item packaged with the said optical functional film because at least one part of the optical functional film of this invention as mentioned above heat-shrinks. Such an article is provided with a discriminating function due to blue shift to a heat-shrinkable film as a packaging material. Therefore, the article itself is provided with an identification function by blue shift. Moreover, since the packaging with the optical functional film of the present invention closely adheres to the curved surface and unevenness of the article by the heat shrinkage function, the film is removed without breaking the packaging film (that is, the packaging state is unraveled). It is difficult.

  Also, if the optical functional film that has shrunk is torn apart by force, the multilayer structure deeply related to the optical function is torn, and it is impossible to repair the torn part so that it cannot be visually confirmed. It becomes difficult. Therefore, once the seal by packaging is broken, the history cannot be erased. This is a useful function in preventing reuse of packaging. In addition, by utilizing this property, the optical functional film of the present invention can also be used as a sealing material for identifying that the seal is not released.

  This invention can also be grasped | ascertained as a manufacturing method of an optical function film. That is, the method for producing an optical functional film of the present invention is a method for producing an optical functional film having a structure in which light transmissive films having different refractive indexes are laminated in multiple layers, and having a light transmissive property having different refractive indexes. It is characterized by comprising a lamination step of laminating films in multiple layers, and a stretching step in which a stretching process is performed on the laminated structure obtained by the laminating step to simultaneously adjust the heat shrinkability and the refractive index of each layer.

  The present invention also provides a coating of an article covered with an optical functional film comprising a coating step of covering the article with the optical functional film described above and a heat shrinking step of heat-shrinking at least a part of the optical functional film. It can also be grasped as a method.

  Since the optical functional film of the present invention is thermally shrunk in accordance with the shape of the substrate by heat shrinkage, it can be used as a film that covers unevenness and curved surfaces and exhibits optical functions.

  According to the present invention, by providing a heat-shrinkable property that can be used for packaging an article to a laminate in which light-transmitting films having different refractive indexes are laminated, the article can be obtained by a heat shrinking action without causing an increase in cost. An optical functional film that can be packaged is provided. This optical functional film can be handled in the same way as a heat-shrinkable film conventionally used for packaging and display of articles and has a high optical identification function. It can be costly. For this reason, the authenticity determination function can be given to any article without increasing the cost.

(First embodiment)
1-1. Configuration of First Embodiment FIG. 1 is a cross-sectional view showing an outline of an optical functional film of the present embodiment. FIG. 2 is a perspective view showing an outline of the optical functional film of FIG. As shown in FIG. 1, the optical functional film 101 has a cross-sectional structure in which an adhesive layer 102, a light absorbing layer 103, a multilayer thin film film layer 104, and a print display layer 105 are laminated. As shown in FIG. 2, the optical functional film 101 has a thin flexible film shape.

  The adhesive layer 102 has an adhesive function for attaching the optical functional film 101 to an article. In this example, a heat-sensitive hot melt agent is applied as the adhesive layer 102. The heat-sensitive hot melt is an adhesive material that melts when a predetermined heat is applied and exhibits an adhesive function. As the adhesive layer, an adhesive material used for sealing may be used. In this case, the release paper is attached to the adhesive layer before use, the release paper is peeled off at the time of application, and the application is applied to the object to be applied by the function of the adhesive material.

  The light absorption layer 103 is a layer that absorbs light in the visible light band. In this example, the light absorption layer 103 is configured by printing black ink. The light absorption layer 103 may be formed of a resin film in which carbon black is dispersed. As the light absorption layer, an ink or a material having a color that absorbs light in a visible light band such as dark blue or green to some extent can be used. The light absorption layer may be obtained by applying and curing an adhesive in which a material that absorbs light in the visible light band such as carbon black is dispersed.

  Moreover, you may employ | adopt the structure which served as the contact bonding layer and the light absorption layer. For example, when an adhesive mixed with powder of a material that absorbs visible light such as carbon black is applied to form the adhesive layer 102, the adhesive layer 102 also functions as a light absorbing layer. In this case, the light absorption layer 103 can be omitted.

  The multilayer thin film layer 104 has a structure in which light-transmitting resin films that transmit visible light having two kinds of refractive indexes are alternately laminated. In this example, a laminated structure in which 201 layers of two kinds of PET (polyethylene terephthalate) films having different refractive indexes with additives are alternately laminated is adopted. In this example, a PET film obtained by copolymerizing 15 mol% of an additive isophthalic acid is used to set a difference in refractive index between the PET films. Here, the multilayer thin film layer 104 functions as a layer exhibiting heat shrinkability and blue shift.

  Additives used for the purpose of controlling the refractive index include aromatic carboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and azelaic acid. .

  The printed display layer 105 has a design as shown in FIG. 2 printed on one surface of an aluminum foil, and an arbitrary logo is displayed on the metallic gloss surface. The print display layer 105 does not cover the entire multilayer thin film layer 104, and the multilayer thin film 104 is exposed in the region 106. That is, as shown in FIG. 2, when the surface of the optical functional film 101 on the side of the print display layer 105 is viewed, the glossy metallic surface and the print content of the print display layer 105 are visually recognized in the region 107, and the multilayer is displayed in the region 106. The thin film layer 104 is visible.

  Therefore, when the surface on the print display layer 105 side is viewed, it is possible to visually recognize the print contents of the area 107 and the blue shift of the area 106. In this case, when the viewing angle with respect to the optical functional film 101 is increased (that is, when viewed from a direction parallel to the surface), the printed content of the area 107 is the same as when the normal printing surface is viewed from an oblique direction. However, as the viewing angle becomes larger, the appearance of the region 106 changes so as to be reflected by the color on the shorter wavelength side. For example, as the viewing angle is increased, the area 106 appears to change its color tone such as red → green → blue.

  The printed display layer 105 is formed by evaporating an aluminum foil on the surface of the multilayer thin film layer 104. Further, instead of using an aluminum foil as the print display layer 105, it is also possible to form characters and designs on the multilayer thin film layer 104 directly by printing and use them as the print display layer.

  As a combination of materials for obtaining a multilayer thin film layer exhibiting heat shrinkability and blue shift, a first film made of polyethylene-2,6-naphthalate and a second film made of copolyethylene terephthalate are alternately used. A layered structure can also be employed. In addition, polystyrene, polypropylene, vinyl chloride, polyethylene, and the like can be used as other materials constituting the multilayer thin film layer. A combination of two or more of the materials exemplified above can also be used. In practicing the present invention, it is important to laminate light-transmitting films having different refractive indexes so that the interfaces between films having different refractive indexes exist in multiple layers so that a blue shift appears.

1-2. Manufacturing Method of Embodiment Hereinafter, an example of a manufacturing method of the optical functional film 101 shown in FIGS. 1 and 2 will be described. First, a method for producing the multilayer thin film layer 104 will be described. The multi-layered thin film layer 104 is formed by alternately stacking 201 first layers made of PET material and second layers in which 15 mol% of isophthalic acid, which is an additive for adjusting the refractive index, is added to the PET material. Then, by applying pressure, the layers are brought into close contact and integrated.

  And heat shrinkability is provided by adding a uniaxial stretching process, adding the temperature of 90 degreeC. The multilayer thin film layer 104 obtained under these stretching conditions has a property of shrinking to about 60% in dimension ratio when a temperature of 150 ° C. is applied.

  When the multilayer thin film layer 104 is obtained, black ink is printed on one surface thereof to form the light absorption layer 103. Further, a heat-sensitive hot melt agent is applied to the exposed surface of the light absorption layer 103 to form the adhesive layer 102. In addition, an aluminum foil is vapor-deposited on the other surface, and printing is further performed to form the printed display layer 105.

  A primer layer may be formed to improve the adhesion of the ink to the printing surface on which printing is performed and to protect the printing surface. The primer layer may be formed by applying a solvent dilution type coating agent mainly composed of a resin material such as a vinyl chloride / vinyl acetate copolymer resin, a polyester resin, or a polyurethane resin and drying it. This primer layer can also be used when another layer such as a multilayer thin film is selected as the printing surface.

  Thus, the optical functional film 101 shown in FIGS. 1 and 2 is obtained. Although the thickness of each layer can be arbitrarily set, in this embodiment, the thickness of the adhesive layer 102 is 10 μm, the thickness of the light absorption layer 103 is 10 μm, the thickness of the multilayer thin film layer 104 is 20 μm, and print display The thickness of the layer 105 was 5 μm. As the adhesive layer 102, an adhesive layer that melts at a temperature of 70 ° C. and exhibits adhesive strength was used.

  In addition, you may add a heat setting process with respect to the multilayer thin film film layer 104 in order to control heat-shrinkability. A heat setting process is a process which suppresses the shrinkage | contraction in subsequent heating by heating in the state which applied the surface pressure. By performing the heat setting treatment, it is possible to adjust the degree of heat shrinkage in the subsequent process.

1-3. Application of Embodiments Hereinafter, an example in which a dry battery is packaged using the optical functional film 101 shown in FIGS. 1 and 2 will be described. FIG. 3 is a schematic diagram showing an operation process for packaging a dry battery with an optical functional film. First, the optical functional film 101 shown in FIGS. 1 and 2 is prepared, and the adhesive layer 102 is caused to exhibit an adhesive function by applying heat at 80 ° C. A battery in this state is wound around the dry battery 305 as shown in FIG. 3A to obtain the state shown in FIG. Thereby, the dry cell 305 and the optical function film 101 adhere. At this time, the width of the optical functional film 101 is longer than the length of the dry battery 101 so that the optical functional film 101 protrudes slightly at both ends of the dry battery 305. FIG. 3B shows the protruding portions 306 and 307.

  3A, the direction of uniaxial stretching performed on the multilayer thin film layer 104 (see FIG. 1) of the optical functional film 101, the circumferential direction of the dry battery 305 (the circumferential direction of the cylindrical surface), and Are matched. By doing so, heat shrinkage at the edge portions of both ends of the dry battery can be smoothly performed in accordance with the shape of the dry battery 305.

  Next, the portions indicated by reference numerals 306 and 307 protruding from both end portions of the dry battery 305 are selectively heated to a temperature of 155 ° C. This heating causes the portions 306 and 307 to thermally shrink, and the edge portion of the end face of the dry battery 305 is encased in the optical functional film 101 as indicated by the reference numeral 309 in FIG. In this way, the dry battery 308 packaged with the optical functional film 101 is obtained.

  In the dry battery 308, a normal product name or the like is printed and displayed at the portion indicated by reference numeral 310, and the portion indicated by reference numeral 311 indicates a blue shift identification function.

  Since the dry cell is a cylinder, the portion 311 has a unique appearance showing a gradation that follows a blue shift in the circumferential direction. This appearance is finely adjusted according to the stretching conditions applied to the multilayer thin film layer 104. Therefore, it is difficult to reproduce this unique appearance from the finished product unless detailed manufacturing conditions are known. In particular, since the multilayer thin film layer 104 is integrated and it is extremely difficult to separate the constituting PET layer into a single layer, it is not easy to reproduce the appearance of the blue shift by reverse engineering. Accordingly, it is extremely difficult to manufacture a counterfeit product of the dry battery 308, which is difficult to identify authenticity.

  Moreover, you may print a character and a pattern on the exposed surface of the multilayer thin film 104 in the part of 311. By doing so, it is possible to obtain an optical function in which the background of printed characters and designs shows a blue shift.

  Moreover, you may form a character and a pattern using the light absorption layer 103 in the part of the code | symbol 311. FIG. That is, you may form the partial light absorption layer by a character and a pattern by printing. In this case, the characters and designs formed by the light absorption layer 103 show a blue shift and are visually recognized as a display with a specific color.

  Further, on the light absorption layer 103, characters and designs that look different from the light absorption layer 103 may be formed by printing. In this case, it is possible to obtain a visual effect in which a printed content showing a blue shift having a hue different from the background appears on the background showing the blue shift.

  Further, as shown in FIG. 3C, the optical functional film 101 is shrunk (shrink) in accordance with the shape of the dry battery 305, so it is difficult to remove it from the dry battery 305 and reuse it. This is because heat shrinkage is an irreversible change, and once heat shrinkage cannot be restored.

  Further, the heat-shrinked portion of the multilayer thin film 104 also exhibits a blue shift. Since this blue shift is influenced by the contracted shape, it shows a more peculiar appearance. This is advantageous as an identification medium that is difficult to counterfeit and has high identification. In addition, the method of wrapping an article with an optical functional film using the thermal shrinkage exemplified here is advantageous in that mass production is possible in a flow operation and the cost is not increased.

Further, as the stretching process for the multilayer thin film layer 104 (see FIG. 1) of the optical functional film 101, biaxial stretching may be performed to impart heat shrinkability in the cylindrical axis direction of the dry battery 305. Since the degree of heat shrinkage in a predetermined direction can be adjusted by the stretching process, the degree of heat shrinkage in the direction may be finely adjusted in accordance with the delicate shape of the dry battery 305.
1-4. Other Packaging Methods FIG. 4 is a schematic diagram illustrating another example of a packaging method for a dry battery using the above-described optical functional film. In the method shown in FIG. 4, an optical functional film 402 having a longitudinal shape is manufactured and wound into a roll shape 401. In addition, as an optical function film, the thing of the structure which does not provide the contact bonding layer 102 in the structure shown in FIG. 1 is prepared.

  First, as shown in the drawing, the optical functional film 402 having a longitudinal shape wound around a roll shape 401 is pulled out and cut into a predetermined length by a cutter 403 to obtain the optical functional film 101. Next, the cut optical functional film 101 is rounded into a cylindrical shape 405, and the rounded one is put on the dry battery 305.

  And the heating for performing heat contraction is performed, and the optical function film made into the cylindrical shape is heat contracted. Due to this thermal contraction, the cylindrical shape 405 is contracted as a whole, and the portions 306 and 307 of the optical functional film 101 that protrude from both ends of the dry cell 305 are shrunk while being folded inward so as to cover the edge portion of the end surface of the dry cell 305. To do. Thus, the dry battery 308 packaged with the optical functional film is obtained. In this example, the function of the adhesive material is not used, and the optical functional film is thermally shrunk, so that the dry battery 305 is packaged so as to be tightened. In addition, since the reference numerals 305 and 307 are three-dimensionally covering the edge portion of the end face of the dry cell, it is possible to obtain a packaging state in which the optical functional film does not cause a firm shift without using an adhesive. Can do.

2-1. Other Embodiments Hereinafter, variations of the structure of the optical functional film will be described. 5-7 is sectional drawing which shows the structure of other embodiment.

  FIG. 5 shows an optical functional film 500 including an adhesive layer 501, a light absorption layer 502, and a multilayer thin film layer 503. As for this optical functional film 500, the multilayer thin film 503 has heat shrinkability, and the entire film shrinks when heated. In this example, the entire multilayer thin film 503 is visually recognized and the blue shift is observed.

  In this example, characters, designs, etc. may be printed on the exposed surface of the multilayer thin film 503. In this case, it is possible to obtain a visual effect in which the printed content appears against the background of the blue shift display indicated by the multilayer thin film 503.

  Moreover, you may form a character and a pattern using the light absorption layer 502. FIG. That is, you may form the partial light absorption layer by a character and a pattern by printing. In this case, the characters and designs formed by the light absorption layer 502 show a blue shift and are visually recognized as a display with a specific color.

  Further, on the light absorption layer 502, characters or designs that look different from the light absorption layer 502 may be formed by printing. In this case, it is possible to obtain a visual effect in which a printed content showing a blue shift having a hue different from the background appears on the background showing the blue shift.

  FIG. 6 shows an optical functional film 600 including an adhesive layer 601, an aluminum foil 602, a printed display layer 603, and a multilayer thin film layer 605. Here, the print display layer 603 is a light-transmitting film, and a print display 604 using black ink is printed on the surface thereof.

  In this configuration, the print display 604 is clearly recognized by the blue shift. In this configuration, since the portion other than the printed display 604 is reflected from the aluminum foil 602, the blue shift in the multilayer thin film layer 605 is difficult to observe (or not noticeable), and in the printed display 604 portion, to the printed portion. Therefore, the interference of the reflected light in the multilayer thin film layer 605 can be easily observed. For this reason, the printed display 604 appears to emerge due to the blue shift phenomenon in the background of the sparkling reflected light.

  FIG. 7 shows an optical functional film 700 including an adhesive layer 701, a light absorption layer 702, a multilayer thin film film layer 703, and a hologram layer 704.

  The hologram layer 704 is a layer made of a light-transmitting material that easily imparts the uneven shape that constitutes the hologram 705. Examples of such a material include polyester resin, polystyrene resin, polypropylene resin, and polyethylene resin. According to this configuration, a visual effect can be obtained in which the hologram 705 emerges due to blue shift. In addition, by forming the hologram on the surface on the viewing side, the hologram can be easily recognized, and the function of the hologram can be effectively utilized. Note that a hologram layer may be provided between the light absorption layer 702 and the multilayer thin film layer 703.

  The hologram function does not have a structure in which the hologram layer 704 is provided separately, but by directly forming an uneven structure or an embossed structure for obtaining a hologram effect on one or both surfaces above or below the multilayer thin film layer 703. May be obtained.

2-2. Application to other articles Examples of articles covered with the optical functional film of the present invention include various things other than dry batteries. Here, the example in the case of utilizing the optical function film of this invention for packaging of the bottle of drinking water and the container (bottle) of cosmetics is demonstrated. FIG. 9 is a schematic diagram showing a procedure for packaging a bottle with an optical functional film.

  In this example, an optical functional film 902 having a longitudinal shape is manufactured, and a roll shape 901 is used. In addition, as an optical functional film, the thing which is not equipped with the contact bonding layer 102 in the structure illustrated in FIG. 1 is used.

  First, an optical functional film 904 is obtained by drawing out a longitudinal optical functional film 902 wound up in a roll shape 901 and cutting it into a predetermined length by a cutter 903. Next, the cut optical functional film 904 is rounded into a cylindrical shape 905, and the rounded product is put on a bottle 906.

  At this time, the direction of uniaxial stretching with respect to the multilayer thin film layer of the optical functional film is made to coincide with the circumferential direction of the cylindrical shape 905. By carrying out like this, the thermal contraction which followed the shape of bottle 906 can be performed. Depending on the shape of the bottle 906, the multilayer thin film layer of the optical function film may be biaxially stretched to cause two-dimensional heat shrinkage.

  Then, heating for causing heat shrinkage is performed, and the optical functional film rolled into the cylindrical shape 905 is shrunk. At this time, the optical functional film 904 rolled into the cylindrical shape 905 contracts along the curved surface of the bottle 906. In this way, the bottle 907 packaged with the optical functional film is obtained.

  In this packaging, since the optical functional film 904 formed in the cylindrical shape 905 contracts along the shape of the bottle 906, a packaging state that does not come off can be obtained without bonding with an adhesive. . Moreover, the packaging by such a method can be mass-produced in a flow operation and is extremely advantageous in terms of cost. In this way, an effective authentication function can be provided without increasing the cost.

  INDUSTRIAL APPLICABILITY The present invention can be used for packaging articles such as dry batteries and daily necessities, and can give an authenticity determination function to those articles. The present invention is not limited to the authenticity determination function, and can be used for packaging and coating of any article as an optical functional film that can observe the blue shift effect and can cover the unevenness and curved surface of the article by the heat shrink function. it can.

It is sectional drawing which shows the cross-section of an optical function film. It is a perspective view which shows the outline | summary of an optical function film. It is a schematic diagram which shows the process of packaging a dry cell with an optical function film. It is a schematic diagram which shows the other process of packaging a dry cell with an optical function film. It is sectional drawing which shows the cross-section of another optical function film. It is sectional drawing which shows the cross-section of another optical function film. It is sectional drawing which shows the cross-section of another optical function film. It is a conceptual diagram explaining the principle of the blue shift which a multilayer thin film shows. It is a schematic diagram which shows the process of packaging a bottle with an optical function film.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Optical function film, 102 ... Adhesive layer, 103 ... Light absorption layer, 104 ... Multilayer thin film layer, 105 ... Print display layer, 106 ... Area | region which shows a blue shift, 107 ... Area | region where print display is visible, 305 ... Dry battery, 306: The portion of the optical functional film that protrudes from the end of the dry cell, 307: The portion of the optical functional film that protrudes from the end of the dry cell, 308 ... The dry cell wrapped by the optical functional film, 309 ... The heat shrinkable end surface of the dry cell Covered portion of optical functional film, 310: portion where normal print display is performed, 311: portion which expresses identification function by blue shift, 401: longitudinally-shaped optical functional film wound up in roll shape, 402: longitudinal Shape optical functional film, 403... Cutter, 405... Optical functional film rolled into a cylindrical shape, 500 Optical functional film, 501 ... Adhesive layer, 502 ... Light absorbing layer, 503 ... Multilayer thin film layer, 600 ... Optical functional film, 601 ... Adhesive layer, 602 ... Aluminum foil, 603 ... Print display layer, 604 ... Print display, 605 ... multilayer thin film layer, 700 ... optical functional film, 701 ... adhesive layer, 702 ... light absorption layer, 703 ... multilayer thin film film layer, 704 ... hologram layer, 705 ... hologram, 801 ... light transmission having first refractive index 802... Light transmissive thin film having a second refractive index, 803... Multilayer thin film layer, 901... Longitudinal optical functional film wound in roll shape, 902. Functional film, 903 ... cutter, 904 ... optical functional film, 905 ... optical functional film rolled into a cylindrical shape, 90 ... bottles, 907 ... packaged bottles optical function film, 908 ... partial heat shrinking treatment.

Claims (16)

It has a laminated structure in which light transmissive films having different refractive indexes are laminated in multiple layers,
An optical functional film having heat shrinkability for packaging an article by heat shrinkage.   The optical functional film according to claim 1, wherein the laminated structure is provided with heat shrinkability by stretching. The stretching process is uniaxial stretching,
The optical functional film according to claim 1 or 2, wherein heat shrinkability in a direction in which the uniaxial stretching is performed is controlled. The stretching process is biaxial stretching,
The optical functional film according to claim 1, wherein the two-dimensional heat shrinkability on the stretched surface is controlled.   The optical functional film according to any one of claims 2 to 4, wherein anisotropy is imparted to the heat shrinkability by the stretching treatment.   6. The optical functional film according to claim 2, wherein anisotropy is imparted to the optical function in the film plane by the stretching treatment.   The optical functional film according to claim 1, further comprising a light absorption layer.   The optical functional film according to claim 1, which exhibits a blue shift phenomenon according to an increase in viewing angle.   9. The optical functional film according to claim 1, wherein hologram processing is applied to at least a part of the laminated structure.   The optical functional film according to claim 1, further comprising a hologram processing layer subjected to hologram processing.   The optical function film according to any one of claims 1 to 10, wherein a shrinkage ratio upon heating is 25% or more in terms of a dimensional ratio. In a state along the curved surface shape,
The optical functional film according to claim 1, wherein a color change is observed in a curved direction of the curved surface.   The optical functional film according to any one of claims 1 to 12, wherein the heat shrinkability is controlled by preliminarily applying a heat setting treatment in which heating is performed in a state where shrinkage cannot be performed.   The article | item characterized by being packaged with the optical functional film in any one of the said Claims 1-13 by heat shrinking at least one part of the said optical functional film. A method for producing an optical functional film having a structure in which light transmissive films having different refractive indexes are laminated in a multilayer structure,
A laminating step of laminating light transmissive films having different refractive indexes in multiple layers;
A method for producing an optical functional film, comprising: a stretching step for subjecting the laminated structure obtained by the laminating step to a stretching treatment to impart heat shrinkability. A covering step of covering the article with the optical functional film according to any one of claims 1 to 13,
A method for covering an article covered with an optical functional film, comprising: a heat shrinking step of heating and heat shrinking at least a part of the optical functional film.

Images