Method for continuously producing an interferential film comprising a synthetic resinous film and a graphene film covering the synthetic resinous film, wherein the graphene film has a total light transmission of 85% or more and a thickness equal to or less than that of the 2nm of the synthetic resinous film

Abstract

To provide an interference film which is not deteriorated by irradiation with ultraviolet rays, does not change with time even when exposed outdoors for a long period of time, has a surface having water repellency and antifouling properties, has mechanical strength higher than that of a metal film, can freely change a hue emitted by light causing an interference phenomenon, and has noncombustibility and corrosion resistance. Further, the whole surface of the interference film is covered with a coating film excellent in transparency and having a thickness smaller by three digits than the thickness of the interference film to realize the properties of the interference film.SOLUTION: A graphene film 1 having a thickness of 2nm or less and a total light transmission of 85% or more is prepared by joining a group of graphenes in which flat surfaces of the graphenes are overlapped with each other. Further, an interference film having a structure in which the entire surface of a transparent synthetic resin film 2 having a thickness causing an interference phenomenon of reflecting only a light beam having a specified wavelength is covered with the graphene film by friction welding is continuously formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The interference film of the present invention is an interference film that causes an interference phenomenon in which light rays having a specific wavelength are reflected. The thickness of the synthetic resin film is set to a thickness that causes an interference phenomenon in which light rays having a specific wavelength are reflected, and further, the entire surface of the synthetic resin film is covered with a graphene film that is friction-welded to a thickness of 2 nm or less, has a total light transmittance of 85% or more, has excellent transparency, and has almost no mass. Specifically, if the thickness of the interference film that causes the interference phenomenon is d, the wavelength of the light that causes the interference phenomenon is λ, and the refractive index of the interference film at that wavelength is n, then the relationship d = (m + 1 / 2) / 2 · λ / n holds. Here, m is an integer. Therefore, when m = 1, the thinnest interference film will cause the interference phenomenon. However, since synthetic resin interference films are thin (0.2-0.3 μm), it is currently difficult to manufacture synthetic resin films with a thickness of 0.2-0.3 μm. On the other hand, if the difference between the thicknesses d that cause the interference phenomenon, which are integers m and (m-1), is greater than the deviation in the thickness of the synthetic resin film, the interference phenomenon caused by the interference film with a thickness of integers m and (m-1) will not overlap. On the other hand, if the difference in the film thickness d between the integer values ​​m and (m+1) that causes the interference phenomenon is less than the deviation in the thickness of the synthetic resin film, then the interference phenomenon caused by the interference film consisting of the integer values ​​m and (m+1) will overlap. Therefore, it is necessary to find an integer value m such that the difference in the film thickness d between the integer values ​​m and (m-1) that causes the interference phenomenon is greater than or equal to the deviation in the thickness of the synthetic resin film, and the difference in the film thickness d between the integer values ​​m and (m+1) that causes the interference phenomenon is less than the deviation in the thickness of the synthetic resin film. On the other hand, if the thickness of the synthetic resin film is 3.0 μm or more, then it is possible to produce a synthetic resin film. Furthermore, if the thickness deviation of a synthetic resin film is 3.0% of the thickness, it is necessary to use an integer value ranging from the first integer value m at which the film thickness d is 3.0 μm or more, to the second integer value m at which the difference in film thickness d between the integer value m and the integer value (m-1) at which the interference phenomenon occurs is 3.0% or more and the difference in film thickness d between the integer value m and the integer value (m+1) at which the interference phenomenon occurs is less than 3.0%, as the integer value m in the relational expression, use the wavelength of the light ray at which the interference phenomenon occurs as λ in the relational expression, and use the refractive index of the synthetic resin film at the wavelength of the light ray at which the interference phenomenon occurs as n in the relational expression, and find the film thickness d at which the interference phenomenon occurs using the relational expression. Since the entire surface of the interference film is covered with a graphene film having a thickness of 2 nm or less, the interference film has the properties of graphene. In contrast, the thinnest interference film that causes interference is 3.0 μm thick. Therefore, even if the entire surface of a synthetic resin film is covered with a graphene film, the graphene film will continue to exhibit interference because its thickness is 2 nm or less, which is three orders of magnitude thinner than the thickness of the synthetic resin film. Furthermore, when frictionally welding a graphene film to the surface of a synthetic resin film, if the synthetic resin film is elastically deformed and the graphene film is frictionally welded to the surface of the elastically deformed synthetic resin film, the graphene film having a thickness of 2 nm or less is reliably frictionally welded to the surface of the synthetic resin film. In other words, the interference film of the present invention is based on the idea that the thickness of the synthetic resin film causes an interference phenomenon in which light rays having specific wavelengths are reflected, and the weak points of the synthetic resin film are covered by the graphene film covering the entire surface of the synthetic resin film. In other words, synthetic resin films have few restrictions on width, length, and thickness, and are lightweight and inexpensive. On the other hand, synthetic resin films have low mechanical strength, are flammable, and have low corrosion resistance. Therefore, if the entire surface of the synthetic resin film is covered with a coating made of a material that has high mechanical strength, is non-flammable, and is highly corrosion-resistant, the weaknesses of the synthetic resin film can be overcome. Furthermore, if the thickness of the film covering the entire surface of the synthetic resin film is three orders of magnitude thinner, the interference phenomenon caused by the synthetic resin film will not be inhibited. Graphene is a two-dimensional layered material whose thickness corresponds to the size of a carbon atom, and the properties of the flat surfaces of the two-dimensional layered graphene are the properties of graphene. Therefore, a graphene film made by directly friction welding graphene flat surfaces together has the properties of graphene because it is made up of a collection of graphene flat surfaces. Graphene also has extremely high transparency, with a total light transmittance of 97.7%. Therefore, a graphene film in which five graphene flats are bonded together has a thickness of 1.7 nm and a total light transmittance of 89%. A graphene film in which six graphene flats are bonded together has a thickness of 2.0 nm and a total light transmittance of 87%. A graphene film in which seven graphene flats are bonded together has a thickness of 2.3 nm and a total light transmittance of 85%. Therefore, graphene films with a thickness of 2 nm or less have excellent transparency, with a total light transmittance of 85% or more. Therefore, light passes through the graphene film with high transmittance and enters the synthetic resin film. The total light transmittance of transparent plate glass is 85-90%. Furthermore, graphene has a surface area per unit mass of 3000 m 2 / g. It also has a large Young's modulus of 1020 GPa, making it the most stretchable and bendable material. It also has a large shear modulus of 440 GPa, making it the strongest material. It also has a thermal conductivity of 19.5 W / Cm, which is 4.5 times that of silver, the metal with the highest thermal conductivity. Furthermore, it has a maximum current density of 360 MA / cm 2 , which is more than 100 times that of copper. 7 It has excellent conductivity of 15,000 cm S / m. 2 / Volt·sec, and the mobility of silicone is 1400 cm 2 Its value is more than one order of magnitude higher than 1 / volt·second. It also has a melting point of over 3000°C, making it a highly heat-resistant material. Furthermore, because it is a single-crystal material made up of a collection of carbon atoms, it has excellent corrosion resistance and does not react with acids or alkalis. Furthermore, graphene films are made of graphene, a genuine substance consisting only of the basal planes of graphite crystals. The extremely large aspect ratio of these flat surfaces allows them to be bonded together directly by frictional heat, resulting in a strong bond between the flat surfaces. Furthermore, the surface of the graphene film has a lubricating effect because it has only a 0.332 nm step, which corresponds to the thickness of the graphene. Furthermore, because the flat surfaces of the graphene are bonded together by friction welding, the surface of the graphene film is water-repellent and stain-resistant. Therefore, an interference film in which the entire surface of a synthetic resin film is covered with a graphene film with a thickness of 2 nm or less not only overcomes the weaknesses of synthetic resin films, but also provides an extremely lightweight interference film with the properties of graphene films. The interference phenomenon of light rays occurs when light rays contain various wavelengths, such as sunlight or light from lighting fixtures. This type of light is called incandescent light. However, interference does not occur with light rays that consist of a single wavelength, such as laser light. In Patent No. 7190123, the inventor has applied for an optical interference film, which is a thin film made by bonding a collection of flat metal powder with a submicron thickness and an average particle size of microns with flat surfaces overlapping each other using a collection of metal microparticles that are two orders of magnitude smaller than the average particle size of the flat powder.Although there are differences in thickness of one flat powder particle on both the front and back of the film, this is an optical interference film with a film thickness that reflects multiple light rays that emit the same specific hue. In contrast, the present invention is an interference film that causes an interference phenomenon in which light rays of a specific wavelength are reflected depending on the thickness of the synthetic resin film, and is configured by covering the entire surface of the synthetic resin film with a graphene film that is 2 nm or less thick and has a total light transmittance of 85% or more, and is joined by friction welding.The configuration of the interference film differs from the optical interference film of the prior application. [Background technology]

[0002] Structural color is a luminescence phenomenon caused by microscopic structures close to the wavelength of light. Unlike luminescence caused by dyes or pigments, structural color does not discolor due to ultraviolet light absorption and continues to emit light permanently unless the microscopic structures that cause the luminescence phenomenon disappear. Luminescence occurs through four mechanisms: interference of light rays due to thin film thickness, interference of light rays due to multilayer film thickness, interference of light rays due to minute grooves or protrusions, and scattering of light rays by microparticles. The color of soap bubbles and oil films is due to interference of light rays due to thin film thickness. The color of the inside of a seashell is due to the multilayer structure of calcium carbonate thin films, which causes the various hues to appear due to the interference of light rays reflected from each layer. Compact discs and DVDs store digital information through irregularities engraved on the surface of a thin aluminum film, and these irregularities cause the iridescent appearance of light. The gemstone opal exhibits various hues depending on the angle due to the interference of light rays with regularly arranged silicate microparticles.

[0003] Interference films that exhibit interference phenomena can be used as interference films in a variety of industrial products, including automobiles and home appliances. However, when interference films are used outdoors, it is desirable that they do not deteriorate or change over time even when exposed to ultraviolet light for a long period of time, and that they also have water-repellent and stain-resistant properties. For this reason, it is desirable that the surface of the interference film be made of an inorganic material. Furthermore, if the mechanical strength of the interference film is higher than that of metal films, the applications of the interference film will be expanded.

[0004] However, organic substances are often used as materials that produce structural colors through their microstructures. For example, Patent Document 1 describes how electrodeposition coating of nonionic acrylic polymer microparticles containing sulfonyl or sulfide groups onto a base coating film results in the microparticles being regularly arranged, resulting in structural colors (pearl colors and iridescent colors). However, microparticles made of acrylic polymers have weak bonding strength with the base coating film. Furthermore, because the microparticles are made of a polymer material, they deteriorate over time when exposed to ultraviolet light. Furthermore, Patent Document 2 describes microparticles exhibiting structural color, which are composed of a core made of a metal oxide and a shell made of polydopamine. The use of these microparticles exhibiting structural color is limited to inks used in hard copies. Furthermore, because the outer shell of the microparticles is made of polydopamine, an organic material, it deteriorates over time when exposed to ultraviolet light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-35303 [Patent Document 2] Japanese Patent Application Publication No. 2018-02929 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] An interference film that reflects light rays of specific wavelengths and causes an interference phenomenon must have the following properties: Interference films may be used outdoors for long periods of time. Therefore, the first property is that the interference film does not deteriorate even when exposed to ultraviolet rays for a long period of time. Furthermore, the second property is that the interference film does not change over time even when exposed outdoors for a long period of time. Furthermore, as long as no foreign matter adheres to the surface of the interference film, the interference film will continue to exhibit interference over a long period of time. Therefore, the third property is that the surface of the interference film is water-repellent and antifouling. Furthermore, if the mechanical strength of the interference film is higher than that of a metal film, the applications of the interference film will be expanded. Therefore, the fourth property is that the interference film has higher mechanical strength than a metal film. Furthermore, if the hue of the light beam that causes the interference phenomenon can be freely changed, the interference film will emit light beams of various hues, further expanding the applications of the interference film. Therefore, the fifth property is that the hue of the interference phenomenon can be freely changed. Furthermore, if the surface of the interference film possesses excellent electrical conductivity, excellent thermal conductivity, non-flammability, and excellent corrosion resistance that does not react with acids or alkalis, the applications of the interference film will be further expanded. Therefore, the sixth property is that the interference film possesses excellent electrical conductivity, excellent thermal conductivity, non-flammability, and excellent corrosion resistance. Furthermore, if the coating covering the surface of the interference film is three orders of magnitude thinner than the thickness of the interference film, the coating covering the surface of the interference film does not inhibit the interference phenomenon caused by the interference film. As a result, even if the interference film is endowed with excellent electrical conductivity, excellent thermal conductivity, non-flammability, and excellent corrosion resistance that does not react with acids or alkalis, the interference phenomenon caused by the interference film will continue. Therefore, the seventh property is that the surface of the interference film is covered with a coating three orders of magnitude thinner than the thickness of the interference film. Furthermore, if the coating covering the surface of the interference film has excellent transparency, it does not inhibit the interference phenomenon in which the interference film emits highly saturated light. Therefore, the eighth property is that the coating covering the surface of the interference film has excellent transparency. Furthermore, if there are fewer restrictions on the width and length of the interference film to be manufactured and the interference film can be cut into any shape, there will be fewer restrictions on the shape of the interference film, further expanding the applications of the interference film.Therefore, the ninth property is that there are fewer restrictions on the width and length of the interference film to be manufactured and the interference film can be cut into any shape.Furthermore, if the interference film can be manufactured at low cost using inexpensive materials, the interference film can be used for many purposes. Therefore, the tenth property is that the interference film can be manufactured at low cost using inexpensive materials. The problem that the present invention aims to solve is to find a method for continuously producing an interference film that combines these 10 properties. In addition, in the JIS Packaging Terminology Standards, a plastic film with a thickness of less than 0.25 mm is called a plastic film. In the present invention, the thickness of the synthetic resin that causes the interference phenomenon of reflecting light of a specific wavelength is less than 0.25 mm, so it is described as a synthetic resin film. Furthermore, a collection of graphene in which the flat surfaces of graphene are bonded together has a thickness of 2 nm or less, so it is described as a graphene film. [Means for solving the problem]

[0007] The present invention provides a method for continuously producing an interference film having a configuration in which the entire surface of a synthetic resin film having a thickness that causes an interference phenomenon of reflecting light having a specific wavelength is covered with a graphene film having a thickness of 2 nm or less and a total light transmittance of 85% or more, the method comprising the steps of: One of two parallel flat electrode plates is placed in a vessel having a width wider than the width of the interference film to be produced and a length and depth sufficient to accommodate the following plurality of cylindrical rollers, and the weight of the collection of flake graphite particles or the weight of the collection of lump graphite particles required according to the width, thickness and length of the graphene films to be joined by friction welding to the entire surfaces of both sides of the synthetic resin film is determined in advance, and the collection of graphite particles having this weight is spread evenly on the surface of one of the parallel flat electrode plates, and further, a mixture of graphite particles having a boiling point of 100°C or less and a density at 20°C of 0.80 g / cm is applied. 3The method comprises weighing out an alcohol having a viscosity of 1-2 mPa·sec at 20°C in an amount at least five times the weight of the graphite particle cluster, filling the container with the weighed alcohol, immersing the graphite particle cluster in the alcohol, and then placing the other parallel plate electrode on top of the one parallel plate electrode via the graphite particle cluster, compressing the entire surface of the other parallel plate electrode, and setting the gap between the two parallel plate electrodes to a predetermined gap, thereby separating the two parallel plate electrodes at a predetermined gap via the graphite particle cluster, and immersing the two parallel plate electrodes in the alcohol. Thereafter, a direct current potential difference having a predetermined magnitude is applied to the gap between the two parallel flat electrode plates, whereby an electric field corresponding to the value obtained by dividing the magnitude of the potential difference by the size of the gap between the two parallel flat electrode plates is applied to the collection of graphite particles, and the application of the electric field simultaneously applies a Coulomb force sufficient to destroy the interlayer bonds between the basal planes of the graphite crystals to all of the collection of graphite particles, to all of the π electrons that are responsible for the interlayer bonds between the basal planes that form the graphite particles, whereby all of the interlayer bonds between the basal planes that form the graphite particles are simultaneously destroyed, and collections of graphene corresponding to the basal planes are precipitated in the gap between the two parallel flat electrode plates. Thereafter, the gap between the two parallel-plate electrodes is enlarged, the two parallel-plate electrodes are tilted in the alcohol, and further, an impact acceleration of 0.2 to 0.4 G depending on the size of the two parallel-plate electrodes is repeatedly applied to the two parallel-plate electrodes to move the graphene clusters from the gap between the two parallel-plate electrodes into the alcohol, and then the two parallel-plate electrodes are removed from the container. Furthermore, an ultrasonic homogenizer is operated in the alcohol in the container, and shock waves are continuously applied to the graphene aggregates through the alcohol, whereby the graphene aggregates are separated into individual graphene sheets in the alcohol, and the separated graphene aggregates are dispersed in the alcohol, and thereafter the ultrasonic homogenizer is removed from the container. a first step of repeatedly applying vibration accelerations of 0.3 to 0.5 G in three directions, i.e., forward / backward, left / right, and up / down, to the container depending on the size of the container, thereby forming a suspension made of an aggregate of graphene in which flat surfaces of the graphene overlap each other via the alcohol; A new container is prepared that has the first feature that the width of the container is wider than the width of the synthetic resin film used in the third step, the second feature that a drawing device that draws out the roll of material around which the synthetic resin film is wound is installed at an end of the container, and the third feature that a plurality of cylindrical rollers having the same length and diameter are installed in the container in parallel and spaced apart from each other, and the suspension prepared in the first step is filled into the new container. The arrangement of the plurality of cylindrical rollers in the new container is such that a first roller is installed at a position corresponding to a height at which the top of the first roller comes into contact with the synthetic resin film drawn out from the roll of material and at a position 1 cm or more away from one side of the new container, and a second roller is installed at a position farther away from one side of the new container than the installation position of the first roller by the size of the first roller, and a second step of arranging the rollers in the new container in the above positions, wherein the first roller is positioned at a distance of 1 cm or more from the bottom of the new container, the last roller is positioned at a distance of 1 cm or more from the other side of the new container and at a position where its top is at the same height as the top of the first roller, the second roller is positioned at a distance of 1 cm or more from the other side of the new container by the size of the last roller compared to the position of the last roller, and at a position at least 1 cm away from the bottom of the new container, the same as the bottom of the new container as the second roller, and the remaining rollers are positioned at a distance of 1 cm or more from the bottom of the new container, the same as the bottom of the new container as the second roller, and are equally spaced between the second roller and the second roller, at a distance of no more than twice the diameter of the cylindrical roller; A roll of synthetic resin film wound around the roll of synthetic resin film, which has a first characteristic of having the same width as the width of the interference film to be manufactured and a second characteristic of having a thickness that causes an interference phenomenon of reflecting light rays of a specific wavelength, is set in a roll of synthetic resin film drawing device installed in the new container, and the synthetic resin film is continuously drawn out from the roll of synthetic resin film at the same speed as the rotation speed of the two work rolls of the multi-stage rolling mill used in the fourth step. Thereafter, the leading end of the drawn synthetic resin film comes into contact with the top of the first roller, and then comes into contact with the side of the first roller to draw the synthetic resin film. The leading edge of the synthetic resin film moves along the side of the second roller, which is approximately 1 / 4 of the way up, and then the direction of movement of the synthetic resin film changes downward, moves, is immersed in the suspension, and then comes into contact with the side of the second roller. Since the rotation direction of the second roller is opposite to the rotation direction of the first roller, the leading edge of the synthetic resin film that has come into contact with the side of the second roller comes into contact with the side of the second roller and moves along the side of the second roller, which is approximately 1 / 4 of the way up, and then changes its direction of movement to a direction parallel to the bottom of the new container, and comes into contact with the first roller and the second roller. The synthetic resin film comes into contact with the side surfaces of the rollers in sequence except for the last roller. Since the rotation direction of the rollers is the same as the rotation direction of the second roller, the leading edge of the synthetic resin film that has come into contact with the side surfaces of the rollers in sequence advances through the suspension without changing its direction of movement and comes into contact with the side surface of the second-to-last roller. Since the rotation direction of the second-to-last roller is the same as the rotation direction of the second roller, the leading edge of the synthetic resin film that has come into contact with the side surface of the second-to-last roller the leading edge of the synthetic resin film comes into contact with the side surface of the last roller and moves along the side surface of the last roller, approximately one-quarter of the way around, then changes its direction of movement upward and continues on, rising from the suspension and coming into contact with the side surface of the last roller; since the rotation direction of the last roller is opposite to that of the second-to-last roller, the leading edge of the synthetic resin film that has come into contact with the side surface of the last roller comes into contact with the last roller and moves along the side surface of the last roller, approximately one-quarter of the way around, then changes its direction of movement and moves towards the gap between two work rolls that constitute a multi-stage rolling mill to be used in the fourth step;A third step is a continuous process for the synthetic resin film, from when the synthetic resin film drawn out from the roll comes into contact with the side of the first roller to when the synthetic resin film comes into contact with the side of the last roller and changes its direction of movement toward the gap between the two work rolls that make up the multi-stage rolling mill; First, the first feature is that the two work rolls have the same width, wider than the width of the interference film to be produced; the second feature is that the two work rolls have the same diameter, smaller than 1 / 10 of the width of the interference film to be produced; the third feature is that the gap between the two work rolls is set to a gap having a thickness 10% thinner than the thickness of the synthetic resin film; the fourth feature is that the two work rolls rotate in opposite directions at the same rotation speed, with the time required for one rotation being longer than 10 seconds; and the two work rolls are heated to a temperature 10°C higher than the boiling point of the alcohol constituting the suspension. A multi-stage rolling mill having two work rolls is prepared, which also has a fifth feature that the temperature of the film is increased. Next, the leading end of the synthetic resin film that has been processed in the third step is inserted into the gap between the two work rolls. As a result, the leading end of the synthetic resin film is drawn into the gap between the two work rolls, and the synthetic resin film is continuously subjected to a compressive stress according to the size of the gap between the two work rolls. At this time, first, the alcohol from the suspension that has been evenly attached to the entire surface of the synthetic resin film evaporates, and then the alcohol is evaporated from the entire surface of the synthetic resin film. Then, the graphene aggregates constituting the suspension are deposited with their flat surfaces overlapping each other, and the entire surface of the synthetic resin film is covered with the graphene aggregates with their flat surfaces overlapping each other. Next, compressive stress is applied to the graphene aggregates, and first, the surface layer of the graphene aggregates collapses. The graphene aggregates constituting the surface layer of the graphene aggregates deposited at the edge of the synthetic resin film move to the edge, and the flat surfaces overlap each other at the edge, and the surface layer of the graphene aggregates deposited other than at the edge moves to the edge of the gap between the two work rolls. The graphene moves toward the surface of the graphene aggregate, and the compressive stress is applied to the graphene aggregate, gradually narrowing the gaps between the overlapping flat surfaces of the graphene aggregate. When the flat surfaces come into direct contact with each other, frictional heat is generated on the flat surfaces, and all of the overlapping flat surfaces are bonded together by the frictional heat, forming a graphene film consisting of the graphene aggregate, having a thickness of 2 nm or less and a total light transmittance of 85% or more. The synthetic resin film is elastically deformed, and the thickness of the synthetic resin film is reduced by 10%, and the entire surface of the elastically deformed synthetic resin film is covered witha fourth step of continuously discharging a film, in which the graphene film has been friction-welded and the graphene film has covered the entire surface of the synthetic resin film, from the gap between the two work rolls, and continuously winding up the discharged film by a winder that rotates at the same rotational speed as the two work rolls; The method for continuously carrying out all of these four processes is a method for continuously manufacturing an interference film in which the entire surface of a synthetic resin film, which has a thickness that causes an interference phenomenon in which light rays of a specific wavelength are reflected, is covered with a graphene film that is 2 nm thick or less and has a total light transmittance of 85% or more.

[0008] That is, according to the above-described method for continuously manufacturing an interference film, by continuously performing all four extremely simple steps described below, an interference film is formed in which the entire surface of a synthetic resin film having a thickness that causes interference is covered with a graphene film having a thickness of 2 nm or less and a total light transmittance of 85% or more. This interference film reflects only light rays of a specific wavelength on its surface. In other words, the thickness of the synthetic resin film is sufficient to cause an interference phenomenon in which light rays of a specific wavelength are reflected. Therefore, as described in paragraph 9, the interference film causes an interference phenomenon in which light rays of a specific wavelength are reflected in the visible light wavelength range. According to this interference film forming method, the thickness of the synthetic resin film is set in advance, and the hue emitted by the interference film is determined thereby. That is, a synthetic resin film is prepared having a thickness that causes an interference phenomenon in which light rays of a specific wavelength are reflected. Next, a graphene film that is three orders of magnitude thinner than the thickness of the synthetic resin film covers the entire surface of the synthetic resin film. Therefore, even if the entire surface of the synthetic resin film is covered with a graphene film that is three orders of magnitude thinner than the thickness of the synthetic resin film, the interference phenomenon in which light rays of a specific wavelength are reflected continues. As a result, the hue emitted by the interference film that reflects light rays of a specific wavelength is determined by setting the thickness of the synthetic resin film in advance. The first step involves carrying out the following five steps in succession to separate the graphene into individual sheets in alcohol, and then dispersing the separated graphene aggregates in alcohol. In the first treatment, a collection of flake graphite particles or a collection of lump graphite particles having a weight predetermined according to the width, thickness, and length of the graphene film to be produced is first spread evenly on the surface of one of two parallel flat electrode plates. 3 Below, a container is filled with a weighed amount of alcohol with a viscosity of 1-2 mPa·sec at 20°C, at least five times the weight of the graphite particle cluster. This causes the graphite particle cluster spread across the surface of one of the parallel plate electrodes to be immersed in the alcohol. Next, the other parallel plate electrode is placed on top of the first parallel plate electrode, with the graphite particle cluster between them, and the entire surface of the other parallel plate electrode is compressed, setting the gap between the two parallel plate electrodes to a predetermined distance. This separates the two parallel plate electrodes by a predetermined gap via the graphite particle cluster, and the two separated parallel plate electrodes are immersed in the alcohol. That is, in order to destroy the interlayer bonds between the basal planes of the graphite crystals that form the graphite particles and deposit graphene clusters corresponding to the basal planes in the gap between the two parallel flat electrodes, the gap between the two parallel flat electrodes was set to a predetermined gap, and the two parallel flat electrodes were immersed in alcohol, the weight of which was set to be at least five times the weight of the graphite particle clusters. The second process involves applying a direct current potential difference of a predetermined magnitude to the gap between two parallel-plate electrodes. This applies an electric field equivalent to the magnitude of the potential difference divided by the size of the gap between the two parallel-plate electrodes to the collection of flake graphite particles or the collection of lump graphite particles. This electric field simultaneously applies a Coulomb force sufficient to break the interlayer bonds between the basal planes of the graphite crystals to all of the π electrons that form the interlayer bonds between the basal planes of all of the graphite particles. This simultaneously breaks all of the interlayer bonds between the basal planes that form the flake graphite particles or the lump graphite particles, resulting in the deposition of a collection of graphene corresponding to the basal planes in the gap between the two parallel-plate electrodes. The deposited graphene is a genuine material containing no impurities and consisting solely of graphite crystals. Furthermore, because the two parallel plate electrodes are immersed in alcohol, the graphene aggregates deposited in the gap between the two parallel plate electrodes do not scatter. Furthermore, because alcohol is an insulator, when a potential difference is applied across the gap between the two parallel plate electrodes immersed in alcohol, an electric field is generated in the gap. In other words, most organic compounds, with the exception of ionic liquids, are insulators. Here, we explain the phenomenon in which an electric field applied to the gap between two parallel flat electrode plates simultaneously destroys the interlayer bonds of the basal planes of the graphite crystals that form the graphite particles laid out in the gap between the two parallel flat electrode plates. The carbon atoms that form the graphite crystals in graphite particles have four valence electrons. Three of these valence electrons are σ electrons that form the basal plane, i.e., graphene. These σ electrons are covalently bonded to the σ electrons of three adjacent carbon atoms on the basal plane at 120° angles to each other, forming a two-dimensional, strong hexagonal network structure. The remaining valence electron is a π electron, located in a π orbital extending perpendicular to the basal plane. This π electron weakly bonds with the π electrons of adjacent carbon atoms in the vertical direction perpendicular to the basal plane, and this weak bonding force allows the basal planes to be stacked in layers. In other words, the basal planes, i.e., graphene, are bonded to each other in layers through the interaction of the weakly bonding π orbitals. This makes graphite particles prone to peeling at the basal planes of the graphite crystals, i.e., mechanical anisotropy. This mechanical anisotropy is well known as the lubricity of graphite particles. That is, the mechanical anisotropy is based on the anisotropy of the electronic structure between the bonds between σ electrons and the bonds between π electrons. When an electric field is applied to such graphite particles, a Coulomb force due to the electric field acts on all π electrons. When the Coulomb force acting on the π electrons acts on them with a force greater than the π orbital interaction acting on them, the π electrons are released from the constraints on the π orbitals. As a result, all π electrons leave the π orbitals and become free electrons. As a result, all π electrons that are responsible for the interlayer bonds on the basal plane are no longer on the π orbitals, and all interlayer bonds on the basal plane are simultaneously broken. In other words, when a π electron moves a distance of b between the basal plane layers due to the Coulomb force F, the π electron performs work W (W = b·F). This work W is calculated as 35 millielectronvolts (an electron volt is a unit that represents the amount of energy possessed by an electron, and 1 electron volt is 1.62 x 10 -19When the applied current exceeds 100 joules, the π electrons are released from the constraints of the π orbital interactions and become free electrons. For example, if two parallel flat electrodes are separated by a gap of 100 μm and a direct current potential difference of 10.6 kV or more is applied across the gap, the interlayer bonds of the basal plane are instantly destroyed. In this way, large quantities of graphene can be produced inexpensively by the extremely simple method of applying an electric field to a collection of inexpensive graphite particles. Furthermore, because all interlayer bonds of the basal planes of the graphite crystals are destroyed simultaneously, the resulting fine material is certainly graphene with basal planes made of graphite crystals. The term "aggregate of graphite particles" used here refers to a relatively small amount of graphite particles, approximately 1 g to 100 g. In other words, flake graphite particles or lump graphite particles have a bulk density of 0.2-0.5 g / cm. 3 Graphite is a fine particle with a particle size distribution ranging from 1 to 300 microns. Therefore, it is easy to evenly distribute a collection of graphite particles between two parallel flat electrodes, and it is also easy to apply a potential difference between the two parallel flat electrodes. When a potential difference is applied across the gap between the two parallel flat electrodes, an electric field is generated across the entire area where the graphite particles are evenly distributed. The electric field acts on the π electrons as a Coulomb force greater than the π orbital interaction, and the π electrons are released from the constraints of the π orbitals and become free electrons. As a result, all interlayer bonds on the basal plane of the graphite crystals in the graphite particles are simultaneously broken, and a collection of graphene is precipitated in the gap between the two parallel flat electrodes. Here, we calculate the number of graphene particles that will precipitate in the alcohol. Here, we assume that all graphite particles consist of spheres with a diameter of 25 microns, and that the true density of graphite is 2.25 × 10 3 kg / m 3 Therefore, the weight of one graphite particle is only 1.84 × 10 -8g. Also, assuming that the average thickness of a graphite particle is 10 microns, the interlayer distance is 3.354 angstroms, so a flake graphite particle with a thickness of 10 microns is made up of 297,265 stacked graphenes. Therefore, if all the interlayer bonds on the basal plane are destroyed, a collection of 297,265 graphenes can be obtained from just one spherical graphite particle. Therefore, if all the interlayer bonds on the basal plane are destroyed for a collection of spherical graphite particles weighing just 1 g, the number of graphenes that can be obtained is 1.62 × 10 13 Thus, according to this production method, an enormous number of graphene aggregates can be obtained from an aggregate of a small amount of graphite particles. The third step involves widening the gap between the two parallel-plate electrodes and tilting them in alcohol. An impact acceleration of 0.2-0.4 G, depending on the width and thickness of the graphene film to be produced (i.e., the amount of alcohol in the container), is then repeatedly applied to the container, causing the graphene aggregates to move from the gap between the two parallel-plate electrodes into the alcohol. The two parallel-plate electrodes are then removed from the container. In the fourth process, an ultrasonic homogenizer is operated in the alcohol in the container, and shock waves are continuously applied to the graphene aggregates through the alcohol. This separates the graphene aggregates into individual graphene sheets in the alcohol, and the separated graphene aggregates are dispersed in the alcohol. After this, the homogenizer is removed from the container. In other words, when an ultrasonic homogenizer is operated in alcohol, a huge number of extremely tiny bubbles, each one order of magnitude smaller than the flat surface of graphene, are simultaneously generated, and the bubbles instantly disappear. This phenomenon is repeated continuously in the alcohol according to the vibration period of the ultrasonic vibration frequency (this phenomenon is called cavitation), and the shock waves generated when the huge number of bubbles burst are continuously applied to the entire collection of graphene via the alcohol. Therefore, shock waves are also applied to the flat surfaces of graphene where flat surfaces overlap each other. Incidentally, alcohol has a low viscosity of 1-2 mPa·sec, and a density of 0.80 g / cm at 20°C. 3Because the shock wave is small (<0.05 μm), the rate at which alcohol is excited by the shock wave is low, and much of the shock wave's energy is irradiated onto the graphene without being lost. On the other hand, the bonding between graphene flats is simply due to the flats overlapping, and the bonding force between the flats is extremely small. Furthermore, graphene is extremely thin, at 0.332 nm, and therefore has almost no mass. Therefore, when a shock wave is applied to the overlapping area, the overlapping flats separate, and alcohol penetrates into the gaps between the separated graphene. The separated graphene fragments are dispersed in the alcohol in a short period of time. The graphene produced by destroying the interlayer bonds of the basal planes of graphite particles is a genuine material composed solely of graphite crystals, free of impurities. Furthermore, the graphene separated into individual graphene fragments is also a genuine material composed solely of graphite crystals, free of impurities, due to continued treatment in alcohol. The fifth step involves repeatedly applying vibration accelerations of 0.3-0.5 G in three directions (front-back, left-right, and up-down) depending on the size of the container, resulting in the formation of a suspension consisting of graphene aggregates in which the flat surfaces of graphene overlap with each other via alcohol. In other words, graphene has an extremely thin thickness of 0.332 nm, so its aspect ratio, which is the ratio of the size of the flat surface to the thickness, is extremely large. Graphene also has almost no mass. Furthermore, the flat surfaces of each separated graphene sheet are in contact with the alcohol. On the other hand, alcohol has a density of 0.80 g / cm 3Because the viscosity of alcohol at 20°C is low (1-2 mPa·sec), when vibration acceleration is applied to the container, the alcohol moves in the direction of the vibration acceleration. This movement of the alcohol also causes the graphene to move. On the other hand, graphene with an extremely large aspect ratio moves through the liquid with its flat surface facing up, which places the least stress on the graphene. Therefore, when vibration acceleration in three directions is repeatedly applied to a collection of graphene, the flat surfaces of the graphene become overlapping with each other through the alcohol. Even if a load is then applied to the collection of graphene with the flat surfaces overlapping with each other through the alcohol, the graphene maintains its overlapping state due to the extremely large aspect ratio of graphene and the fact that it has almost no mass. In the second step, a new container is prepared that combines the first feature, in which the width of the container is wider than the width of the synthetic resin film, the second feature, in which a drawing device for drawing the roll of material wound with the synthetic resin film is installed at the end of the container, and the third feature, in which multiple rotating cylindrical rollers of the same length and diameter are installed inside the container, parallel to each other and spaced apart, the length of the width of the container, and the suspension prepared in the first step is filled into the new container. That is, in the third step, the synthetic resin film is continuously drawn from the roll of material wound with the synthetic resin film, and the drawn synthetic resin film is continuously passed through the suspension in the new container by the multiple cylindrical rollers that are spaced apart and parallel to each other in the width direction of the new container. The multiple cylindrical rollers rotate together with the synthetic resin film in contact with the rollers at the same speed as the synthetic resin film is drawn. The arrangement of multiple cylindrical rollers in the new container is as follows: The first roller is placed at a position where the synthetic resin film pulled out from the roll of synthetic resin film in the third step comes into contact with the top of the first roller, and is at least 1 cm away from one side of the new container. The second roller is placed at a position that is farther away from one side of the new container by the size of the first roller than the position where the first roller was placed, and at a position that is at least 1 cm away from the bottom of the new container. The last roller is placed at a position that is farther away from the other side of the new container and at the same height as the first roller. The penultimate roller is placed at a position farther away from the other side of the new container by the size of the last roller than the position where the last roller was placed, and at the same position as the second roller, away from the bottom of the container. The remaining rollers are installed at equal intervals depending on the length of the container, at the same distance from the bottom of the container as the second roller, with a distance between the second roller and the penultimate roller of not more than twice the diameter of the cylindrical roller. In order to continuously produce the interference film, the movement speed of the synthetic resin film was set to the same speed. That is, the speed at which the synthetic resin film was continuously unwound from the roll was set to the same speed as the rotational speed of the two work rolls that make up the multi-stage rolling mill, and the interference film discharged from the gap between the two work rolls needed to be wound up on a winding device that rotates at the same rotational speed as the two work rolls. For this reason, the speed at which the synthetic resin film was continuously unwound from the roll was set to the same speed as the rotational speed of the two work rolls, and the rotational speed of the winding device that winds up the interference film was set to the same speed as the rotational speed of the two work rolls. In the third step, the synthetic resin film drawn from the roll is sequentially brought into contact with multiple cylindrical rollers placed inside a container, and is continuously moved through the suspension at a constant speed, causing the suspension to be adsorbed to a uniform thickness over the entire surface of the synthetic resin film. Because the alcohol has a low viscosity of 1-2 mPa·sec, the thickness of the suspension adsorbed onto the synthetic resin film is less than 100 nm. Furthermore, if the interference film is to have enhanced electrical and thermal conductivity, a relatively high-viscosity alcohol is used. This third step consists of the following processes: First, a roll of synthetic resin film with a thickness that causes interference by reflecting only light of a specific wavelength is placed in a drawing device. The synthetic resin film is continuously drawn from the roll at the same speed as the rotational speed of the two work rolls of the multi-stage rolling mill used in the fourth process. Next, the drawn synthetic resin film moves continuously at the drawing speed applied by the roll drawing device and sequentially contacts multiple cylindrical rollers placed inside the container. That is, the leading edge of the drawn synthetic resin film contacts the top of the first roller, and then moves in contact with the first roller along the side of the cylinder approximately one-quarter of the way up. After this, the direction of movement changes downward, the film is immersed in the suspension, and then it contacts the second roller. Because the rotation direction of the second roller is opposite to that of the first roller, the synthetic resin film that has come into contact with the second roller moves in contact with the side of the cylinder approximately one-quarter of the way up the second roller. After this, the film changes direction of movement parallel to the bottom of the container and comes into contact with the rollers in order, excluding the first roller, the second roller, and the last roller. Because the rotation direction of the rollers is the same as that of the second roller, the synthetic resin film that has come into contact with the rollers in order continues to move through the suspension without changing direction and comes into contact with the penultimate roller. Because the rotation direction of the penultimate roller is the same as that of the second roller, the synthetic resin film that has come into contact with the penultimate roller moves along the side of the cylinder approximately one-quarter of the way from the penultimate roller. After this, the film changes direction of movement upward and continues to move, rising from the suspension and coming into contact with the last roller. Because the rotation direction of the last roller is opposite to that of the penultimate roller, the synthetic resin film that has come into contact with the last roller moves along the side of the cylinder approximately one-quarter of the way from the last roller. Finally, the direction of movement is changed to the direction of the gap between two work rolls that constitute the multi-stage rolling mill used in the fourth step. As described above, the synthetic resin film is continuously drawn off the roll, comes into contact with a plurality of rollers in turn, and moves continuously through the suspension at the same speed at which it is drawn off the roll. Since the synthetic resin film moves continuously at the same speed as it is unwound from the roll, the synthetic resin film that comes into contact with the side of the roller moves with the side of the roller in contact with the roller for approximately 1 / 4 of the distance at the same speed as it is unwound from the roll. For this reason, the multiple cylindrical rollers rotate at the same speed as the synthetic resin film is unwound from the roll. In the fourth step, the synthetic resin film treated in the third step is compressed in the gap between two work rolls that make up a multi-stage rolling mill. First, a multi-high rolling mill having two work rolls is prepared, which has the following characteristics: (1) the two work rolls have the same width, wider than the width of the interference film to be produced; (2) the two work rolls have the same diameter, smaller than 1 / 10 of the width of the interference film to be produced; (3) the gap between the two work rolls is set to a thickness 10% thinner than the thickness of the synthetic resin film; (4) the two work rolls rotate in opposite directions at the same rotational speed, with one rotation time longer than 10 seconds; and (5) the two work rolls are heated to a temperature 10°C higher than the boiling point of the alcohol constituting the suspension. Next, the leading edge of the synthetic resin film that has been processed in the third step is inserted into the nip between the two work rolls. This pulls the leading edge of the synthetic resin film into the nip between the two work rolls, and the synthetic resin film is continuously subjected to a compressive stress corresponding to the size of the gap between the two work rolls. The rotation speed of the two work rolls is such that the time required for one rotation is longer than 10 seconds, ensuring sufficient contact time between the synthetic resin film and the two work rolls. First, the alcohol evaporates from the suspension evenly adhered to the entire surface of the synthetic resin film. Then, graphene aggregates constituting the suspension are deposited on the entire surface of the synthetic resin film, with their flat surfaces overlapping each other. The entire surface of the synthetic resin film is covered with graphene aggregates whose flat surfaces overlap each other. Next, compressive stress is applied to the graphene aggregates, causing the surface layer of the graphene aggregates to collapse. The graphene aggregates deposited on the edges of the synthetic resin film move toward the edges, causing their flat surfaces to overlap each other. The surface layer of the graphene aggregates deposited outside the edges moves toward the rear of the gap between the two work rolls. Next, compressive stress is applied to the graphene aggregates, gradually narrowing the gap between the overlapping flat surfaces of the graphene aggregates. When the flat surfaces come into direct contact with each other, frictional heat is generated between the overlapping flat surfaces of the graphene, and the frictional heat causes the overlapping flat surfaces to bond together, forming a graphene film with a thickness of 2 nm or less and a total light transmittance of 85% or more, consisting of a collection of graphene flat surfaces that are directly overlapping and bonded together.Furthermore, as the graphene film is formed, the synthetic resin film is compressed and elastically deformed, reducing its thickness by 10%. The graphene film is then friction-welded to the entire surface of the elastically deformed synthetic resin film. As a result, a film in which the graphene film covers the entire surface of the synthetic resin film is continuously discharged from the gap between the two work rolls. The discharged film is then continuously wound up by a winder that rotates at the same rotational speed as the two work rolls. By continuously carrying out all four of the above-described processes, an interference film is continuously produced in which the entire surface of a synthetic resin film, which has a thickness that causes interference by reflecting light of a specific wavelength, is covered with a graphene film that is 2 nm thick or less and has a total light transmittance of 85% or more. This interference film exhibits the following effects and solves the 10 problems described in paragraph 6. Because the entire surface of the interference film is covered with a graphene film, the interference film has the properties of graphene. As described in paragraph 1, graphene is a single-crystal material composed of an assembly of carbon atoms, and has excellent corrosion resistance, being unreactive with acids and alkalis. Furthermore, even if the interference film is continuously irradiated with ultraviolet light for a long period of time, the graphene film does not change, so the interference film does not deteriorate. Furthermore, even if the interference film is exposed outdoors for a long period of time, the graphene film does not change, so the interference film does not change over time. Therefore, the first and second problems described in paragraph 6 are solved. In addition, the graphene film has both water repellency and antifouling properties due to the flat graphene surfaces that form the surface of the graphene film. As a result, the surface of the interference film has water repellency and antifouling properties. Therefore, the third problem described in paragraph 6 is solved. Furthermore, because the flat surfaces of graphene, which has an extremely large aspect ratio and is extremely lightweight, are directly bonded together by frictional heat, the flat surfaces of the graphene are firmly bonded together. The graphene film is also firmly bonded to the elastically deformed synthetic resin film by friction welding. Meanwhile, as described in paragraph 1, graphene is the toughest material, with a high shear modulus of 440 GPa. Therefore, the interference film has a mechanical strength greater than that of a metal film. This solves the fourth problem described in paragraph 6. Furthermore, as described in paragraph 1, if the thickness of the synthetic resin film causing the interference phenomenon is d, the wavelength of the specified light ray causing the interference phenomenon is λ, the refractive index of the synthetic resin film at the wavelength λ of the light ray is n, and the integer value is m, then the relationship d = (m + 1 / 2) / 2 · λ / n holds. Note that the refractive index n at the wavelength λ of the specified light ray differs for each synthetic resin film material, so an appropriate integer value m is determined for each synthetic resin film material. Therefore, by determining the wavelength λ of the specified light ray according to the hue emitted by the light ray causing the interference phenomenon and determining the appropriate integer value m, the thickness d of the synthetic resin film causing the interference phenomenon, which reflects the light ray of the specified wavelength, can be obtained. Therefore, the hue of the interference phenomenon can be freely changed depending on the thickness d of the synthetic resin film causing the interference phenomenon. This solves the fifth problem described in paragraph 6. Furthermore, as mentioned in paragraph 1, graphene has a thermal conductivity of 19.5 W / cm, which is 4.5 times that of silver, the metal with the highest thermal conductivity. Also, the maximum current density is 360 MA / cm. 2 , which is more than 100 times that of copper. 7 It has excellent conductivity of 15,000 cm3 / s and electron mobility of 15,000 cm3 / s. 2 / Volt·sec, and the mobility of silicone is 1400 cm 2Its thermal conductivity is more than one order of magnitude higher than 1 / volt·second. Furthermore, its melting point exceeds 3000°C, making it a material with extremely high heat resistance. The graphene film also isolates the synthetic resin film from the atmosphere, making the interference film non-flammable. This allows the interference film to have excellent electrical conductivity, excellent thermal conductivity, and non-flammability. This solves the sixth problem described in paragraph 6. Interference films are nonflammable for the following reasons: If a synthetic resin film is covered with an airtight graphene film that blocks out the outside world, the synthetic resin film will thermally decompose in the extremely narrow gap when the interference film is heated. Therefore, the first flammable gas generated by thermal decomposition is trapped in the extremely narrow gap covered by the graphene film, and the partial pressure of the flammable gas in the narrow gap gradually increases until it reaches the saturation pressure at that temperature, at which point the decomposition stops. Therefore, thermal decomposition does not proceed unless more thermal energy is applied than in an open nitrogen atmosphere. Furthermore, because one mole of flammable gas occupies a volume of 22.4 liters, the saturation pressure of the flammable gas at that temperature is reached in the trapped extremely narrow gap after only a very small amount has been thermally decomposed. Furthermore, since the first flammable gas is already trapped, the second and subsequent flammable gases generated by thermal decomposition require even greater thermal energy to proceed. As a result, the thermal decomposition of the synthetic resin film is shifted to a significantly higher temperature than in a nitrogen atmosphere, and the thermal decomposition proceeds beyond the ignition point of the flammable gas. As a result, the synthetic resin film does not self-ignite due to thermal decomposition of the synthetic resin film when heated, and does not create a fire starting point. Furthermore, because the graphene film has excellent mechanical strength, the graphene film is not destroyed by the gas pressure trapped within it. This makes the interference film non-flammable. Furthermore, a graphene film with a thickness of 2 nm or less is three orders of magnitude thinner than a synthetic resin film. Therefore, even if the graphene film covers the surface of a synthetic resin film, it does not interfere with the interference phenomenon of the synthetic resin film. This solves the seventh problem described in paragraph 6. Furthermore, as described in the first paragraph, a graphene film having a thickness of 2 nm or less has excellent transparency, with a total light transmittance of 85% or more. Therefore, light passes through the graphene film with high transmittance and enters the synthetic resin film. Therefore, the graphene film does not interfere with the interference phenomenon that occurs when the synthetic resin film emits highly saturated light. This solves the eighth problem described in the sixth paragraph. Furthermore, synthetic resin films have fewer restrictions on width and length. Therefore, there are fewer restrictions on the width and length of the interference film to be manufactured. Furthermore, as described in paragraph 1, graphene has a large shear modulus of 440 GPa. On the other hand, since the thickness of graphene films is extremely thin, at 2 nm or less, graphene films can be cut. Therefore, there are fewer restrictions on the width and length of the interference film to be manufactured, and the interference film can be cut into any shape. This solves the ninth problem described in paragraph 6. Furthermore, all of the processes consisting of the above-mentioned four steps are extremely simple. The graphite particles used are a general-purpose industrial material, the alcohol is a general-purpose organic compound, and the synthetic resin film is a general-purpose industrial material. The ultrasonic homogenizer and multi-stage rolling mill are general-purpose processing devices. Therefore, a graphene cluster can be produced by a low-cost production method using a low-cost graphite particle cluster, and an interference film can be produced by a low-cost method. This solves the tenth problem described in paragraph 6. As a result, all 10 problems described in paragraph 6 are resolved.

[0009] Here, the interference phenomenon caused by differences in the thickness of the thin film will be explained. When light strikes the surface of a thin film, part of the wavefront of the light wave is reflected from the top surface of the film. Another part is refracted and enters the interior of the thin film, reflected from the bottom surface, and then refracted again at the top surface, resulting in two light waves interfering at the top surface of the thin film. The light reflected from the top surface of the thin film is reflected from the fixed end, resulting in a phase shift of π. On the other hand, the light that enters the interior of the thin film, is reflected from the bottom surface, and then refracted again at the top surface is reflected from the free end, resulting in no phase shift. The optical path difference between the two light beams is 2n·d·cosθ, where n is the refractive index of the thin film, 1.0 is the refractive index of air, and θ is the angle of refraction. Meanwhile, in Young's interference experiments and interference using diffraction gratings, it has been found that when the optical path difference is an integer multiple of the wavelength of light, where λ is the wavelength of light, the light constructively interacts. Because the phase of the light wave reflected from the top surface is shifted by π, the two light waves constructively interact when the optical path difference is (m+1 / 2)·λ, where m is an integer. Therefore, when the relationship 2n·d·cosθ=(m+1 / 2)·λ holds, light rays will cause interference. Here, when the thin film is at a distance from the observer, the refraction angle is close to zero, so the relationship is 2n·d=(m+1 / 2)·λ. This relationship is well known. However, when the observer moves closer to the thin film, the refraction angle does not become zero, and the wavelength λ of the light rays causing the interference phenomenon observed by the observer shifts to a shorter wavelength by λ·cosθ. As mentioned above, the interference phenomenon in which a thin film thickness d reflects a light beam with a wavelength λ is expressed by the relationship 2n·d=(m+1 / 2)·λ between the film thickness d, the wavelength λ, and the integer value m. In this relationship, the film thickness at which interference occurs is thinnest when the integer value m is 1. However, when the integer value m is 1, the thickness of the synthetic resin interference film that causes interference is as thin as 0.2-0.3 μm, and it is currently difficult to manufacture a synthetic resin film with a thickness of 0.2-0.3 μm. On the other hand, if the thickness of the synthetic resin film is 3.0 μm or greater, it becomes possible to manufacture the synthetic resin film. Therefore, the first challenge in realizing an interference film is to find the first integer value m at which the film thickness d at which interference occurs is 3.0 μm or greater. On the other hand, if the difference in film thickness d between the integer values ​​(m-1) and m, which causes an interference phenomenon, is greater than or equal to the deviation in thickness of the synthetic resin film, the interference phenomenon caused by the interference film formed by the integer values ​​(m-1) and m will not overlap. Conversely, if the difference in film thickness d between the integer values ​​m and (m+1), which causes an interference phenomenon, is less than the deviation in thickness of the synthetic resin film, the interference phenomenon caused by the interference film formed by the integer values ​​m and (m+1) will overlap. Furthermore, the ratio of the values ​​where the integer values ​​(m-1) and m form (m+1 / 2) / 2 is greater than the ratio of the values ​​where the integer values ​​m and (m+1) form (m+1 / 2) / 2, and the ratio between the two gradually decreases as the value of the integer m increases. Therefore, the second integer value m that satisfies the above relationship is the largest integer value m such that the difference in film thickness d between the integer value (m-1) and the integer value m, which causes the interference phenomenon, is greater than or equal to the deviation in the thickness of the synthetic resin film, and the difference in film thickness d between the integer value m and the integer value (m+1) which causes the interference phenomenon, is less than the deviation in the thickness of the synthetic resin film. Therefore, the integer values ​​m between the first integer value m and the second integer value m can be used as the integer values ​​m that satisfy the above relationship. Therefore, finding the second integer value m is the second challenge in realizing an interference film. Note that the refractive index of a synthetic resin film at a specified wavelength of light differs for each material. Therefore, for each synthetic resin film material, it is necessary to find a first integer value m such that the film thickness d that causes the interference phenomenon is 3.0 μm or greater, and a second integer value m such that the difference between the film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m-1) is greater than or equal to the deviation in thickness of the synthetic resin film, and the difference between the film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m+1) is less than the deviation in thickness of the synthetic resin film. Furthermore, by determining the wavelength λ of a specified light ray according to the hue emitted by the light ray causing the interference phenomenon, and then determining an integer value m between the first integer value m and the second integer value m, and using this integer value m to calculate the film thickness d according to the above-mentioned relational expression, the film thickness d of the synthetic resin film causing the interference phenomenon and reflecting the light ray of the specified wavelength can be determined. Therefore, the hue of the interference phenomenon can be freely changed depending on the film thickness d of the synthetic resin film causing the interference phenomenon. Furthermore, since there are multiple integer values ​​m, there are multiple film thicknesses d of the synthetic resin film causing the interference phenomenon and reflecting the light ray of the specified wavelength.

[0010] The method for continuously manufacturing an interference film according to paragraph 7 is a method for continuously manufacturing a first interference film that emits light with relatively high saturation, the method for continuously manufacturing the first interference film comprising: The synthetic resin film described in paragraph 7 is a film made of acrylic resin, and the film thickness d of the film that causes the interference phenomenon of reflecting only light rays having a specific wavelength described in paragraph 7 is such that, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the acrylic resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d of the film that causes the interference phenomenon is 3.0 μm or more, and the difference between the film thicknesses d of the integer value (m-1) and the integer value m that cause the interference phenomenon is a difference that is equal to or greater than the deviation in thickness of the acrylic resin film, and the difference between the film thicknesses d of the integer value m and the integer value (m+1) that cause the interference phenomenon is equal to or greater than the deviation in thickness of the acrylic resin film, a method for continuously producing a first interference film that emits light with relatively high saturation, the method comprising: using an integer value m between the first integer value and the second integer value as the integer value m in the relational expression, the wavelength of the light that causes the interference phenomenon as λ; using the refractive index of the acrylic resin film at the wavelength of the light that causes the interference phenomenon as n in the relational expression; determining a thickness d of a film that causes the interference phenomenon and reflects only light having the wavelength specified by the relational expression; using the acrylic resin film having the thickness d as the synthetic resin film described in paragraph 7; and continuously carrying out all of the processing consisting of the four steps described in paragraph 7, thereby resulting in a method for continuously producing a first interference film that emits light with relatively high saturation.

[0011] In other words, if a synthetic resin film has excellent transparency and a thickness that causes interference, it will become an interference film that emits light with relatively high saturation. Meanwhile, total light transmittance and haze value are indicators of the transparency of synthetic resin films. Total light transmittance is the transmittance of light at all wavelengths of light. The higher the total light transmittance, the more light is transmitted, and therefore the higher the transparency of the synthetic resin film. Furthermore, the haze value is the ratio of diffused light to total transmitted light, and is an indicator of the degree of cloudiness or light diffusion. The lower the haze value, the higher the transparency of the synthetic resin film. Therefore, a film made of a synthetic resin with high total light transmittance and low haze value, and with a thickness that causes interference, will become an interference film that emits light with relatively high saturation. Acrylic resin films have a high total light transmittance of 92-93% and an extremely low haze value of 0.1%, making them the most transparent synthetic resin film. This makes them the first interference film, emitting highly saturated light. On the other hand, as mentioned in paragraph 1, graphene has an extremely high total light transmittance of 97.7%. Therefore, a graphene film with five graphene layers bonded together has a thickness of 1.7 nm and a total light transmittance of 89%. A graphene film with six graphene layers bonded together has a thickness of 2.0 nm and a total light transmittance of 87%. A graphene film with seven graphene layers bonded together has a thickness of 2.3 nm and a total light transmittance of 85%. All of these have high transmittance, allowing light to pass through the graphene film and enter the acrylic resin film. Furthermore, because graphene films have excellent transparency and are three orders of magnitude thinner than acrylic resin films, the interference phenomenon of the acrylic resin film is not inhibited even when the graphene film is bonded to the acrylic resin film. Here, the thickness of the acrylic resin film is set to 3.0 μm or more, the thickness deviation is set to 3.0%, and the film thickness d at which the interference phenomenon occurs is considered. As described in paragraph 9, in the relational equation where d = (m + 1 / 2) / 2 · λ / n holds, the integer value m is clarified from the first integer value to the second integer value in the relational equation, where m is a first integer value at which the film thickness d of the film causing the interference phenomenon is 3.0 μm or more, and m is a second integer value m at which the difference between the film thicknesses d formed by the integer value (m-1) and the integer value m, causing the interference phenomenon, is greater than or equal to the deviation in thickness of the synthetic resin film, and the difference between the film thicknesses d formed by the integer value m and the integer value (m+1) is less than the deviation in thickness of the synthetic resin film, and by using this integer value m to calculate the film thickness d according to the relational equation, the film thickness d of the synthetic resin film causing the interference phenomenon of reflecting light rays of a specified wavelength can be calculated. Using the equation d = (m + 1 / 2) / 2 · λ / n described in paragraph 9, we set the thickness d of an acrylic resin film at which interference occurs to 3.0 μm, and determine the integer m at which the thickness d reaches 3.0 μm. We also set the deviation of thickness d to 3.0% and determine the integer m in the equation. Meanwhile, the thickness d at which interference occurs is proportional to the wavelength λ of the light that causes interference. Furthermore, the larger the integer m, the greater the thickness d at which interference occurs. Therefore, we first consider interference at a wavelength of 433 nm, which exhibits a relatively short, violet hue within the visible spectrum. The refractive index of acrylic resin film at a wavelength of 433 nm is 1.503. At a wavelength of 433 nm, when the integer m increases to 21, the thickness d exceeds 3.0 μm, reaching 3.10 μm. When the integer m is 20, the thickness d at which interference occurs is 2.95 μm. Furthermore, when the integer value m is 22, the film thickness at which interference occurs is 3.24 μm. Furthermore, a film thickness d of 3.10 μm is 4.5% thinner than a film thickness d of 3.24 μm, and the difference between the two easily exceeds the 3.0% thickness deviation of acrylic resin films. Therefore, the interference phenomenon that occurs when the integer value m is 21 does not overlap with the interference phenomenon that occurs when the integer value m is 22. For this reason, when the integer value m is 21 or greater, acrylic resin films cause interference of light with a wavelength of 433 nm. Next, we consider the interference phenomenon in acrylic resin film at a wavelength of 700 nm, which exhibits a relatively long red hue. The refractive index of acrylic resin film at a wavelength of 700 nm is 1.630. When the integer value m is 20, the film thickness at which interference occurs is 4.40 μm. When the integer value m is 21, the film thickness at which interference occurs is 4.61 μm. When the integer value m is 22, the film thickness at which interference occurs is 4.83 μm. The 4.61 μm film thickness is 4.8% thicker than the 4.40 μm film thickness and 4.8% thinner than the 4.83 μm film thickness. Therefore, when the integer value m is 21, the acrylic resin film exhibits interference with light rays at a wavelength of 700 nm. Therefore, the minimum integer value m at which interference occurs in acrylic resin film is 21, based on the results of the interference phenomenon with light rays at a wavelength of 433 nm. On the other hand, the ratio of the film thickness at which interference occurs for integer m to the film thickness at which interference occurs for integer m-1 and the film thickness at which interference occurs for integer m+1, as well as the ratio of the film thickness at which interference occurs for integer m, gradually decrease as the integer m increases in the above-mentioned relationship. Here, we consider the film thickness ratio as the integer m increases. First, at a wavelength of 433 nm, when the integer m is 32, the film thickness d at which interference occurs is 4.68 μm; when the integer m is 31, the film thickness d is 4.54 μm; and when the integer m is 33, the film thickness d is 4.82 μm. 4.68 μm is 3.1% thicker than 4.54 μm and 3.0% thinner than 4.82 μm. Next, for the relatively long wavelength of 700 nm, when the integer value m is 32, the film thickness at which interference occurs is 6.97 μm; when the integer value m is 33, the film thickness at which interference occurs is 7.19 μm; and when the integer value m is 31, the film thickness at which interference occurs is 6.76 μm. A film thickness of 6.97 μm is 3.1% thicker than 6.76 μm and 2.9% thinner than 7.19 μm. Therefore, when the integer value m is 32, an acrylic resin film will cause interference of light with a wavelength of 700 nm. Therefore, the maximum integer value m at which an acrylic resin film will cause interference is 32. As explained above, when the thickness of an acrylic resin film is 3.0 μm or more and the thickness deviation is 3.0%, the acrylic resin film can be manufactured using the relationship d = (m + 1 / 2) / 2 · λ / n, where m is an integer between 21 and 32. Furthermore, the wavelength of the light that causes the interference phenomenon is used as λ in the relationship, and the refractive index of the acrylic resin film at the wavelength of the light that causes the interference phenomenon is used as n in the relationship, and the film thickness d that causes the interference phenomenon is calculated using the relationship. Using an acrylic resin film with this thickness d as the synthetic resin film described in paragraph 7 and continuously performing all four processing steps described in paragraph 7 constitutes a method for continuously manufacturing a first interference film that emits light with relatively high saturation.

[0012] The method for continuously manufacturing an interference film according to paragraph 7 is a method for continuously manufacturing a second interference film that emits light with relatively high saturation, the method for continuously manufacturing the second interference film comprising: The synthetic resin film described in paragraph 7 is a film made of polycarbonate resin, and the film thickness d of the film that causes the interference phenomenon of reflecting only light rays having a specific wavelength described in paragraph 7 is such that, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the polycarbonate resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d of the film that causes the interference phenomenon is 3.0 μm or more, and the difference between the film thicknesses d of the integer value (m-1) and the integer value m that cause the interference phenomenon is greater than or equal to the deviation in thickness of the polycarbonate resin film, and the difference between the film thicknesses d of the integer value m and the integer value (m+1) that cause the interference phenomenon is greater than or equal to the deviation in thickness of the polycarbonate resin film, a second integer m ranging from the first integer to the second integer, the difference being less than the deviation in thickness of the polycarbonate resin film; a wavelength of the light that causes the interference phenomenon being used as λ in the relational expression; a refractive index of the polycarbonate resin film at the wavelength of the light that causes the interference phenomenon being used as n in the relational expression; a film thickness d of a film that causes the interference phenomenon and reflects only light having the wavelength specified by the relational expression being determined; the polycarbonate resin film having the film thickness d being used as the synthetic resin film described in paragraph 7; and a method of continuously carrying out all of the four steps described in paragraph 7 to produce a second interference film that emits light with relatively high saturation.

[0013] In other words, polycarbonate resin films have a high total light transmittance of 88-89% and a low haze value of 0.3-0.4%, making them the second most transparent synthetic resin film after acrylic resin films. This makes them a suitable second-generation interference film, emitting light with high saturation. Furthermore, because graphene films have excellent transparency and are three orders of magnitude thinner than polycarbonate resin films, bonding a graphene film to a polycarbonate resin film does not inhibit the interference phenomenon caused by the polycarbonate resin film. Here, the thickness of the polycarbonate resin film is set to 3.0 μm or more, the thickness deviation is set to 3.0%, and the film thickness d at which the interference phenomenon occurs is considered. As described in paragraph 9, in the relational equation where d = (m + 1 / 2) / 2 · λ / n holds, the integer value m is clarified from the first integer value to the second integer value in the relational equation, where m is a first integer value at which the film thickness d of the film causing the interference phenomenon is 3.0 μm or more, and m is a second integer value m at which the difference between the film thicknesses d formed by the integer value (m-1) and the integer value m, causing the interference phenomenon, is greater than or equal to the deviation in thickness of the synthetic resin film, and the difference between the film thicknesses d formed by the integer value m and the integer value (m+1) is less than the deviation in thickness of the synthetic resin film, and by using this integer value m to calculate the film thickness d according to the relational equation, the film thickness d of the synthetic resin film causing the interference phenomenon of reflecting light rays of a specified wavelength can be calculated. Using the equation d = (m + 1 / 2) / 2 · λ / n described in paragraph 9, we set the thickness d of a polycarbonate resin film at which interference occurs to 3.0 μm, and determine the integer m at which the thickness d reaches 3.0 μm. We also set the deviation of the thickness d to 3.0% and determine the integer m in the equation. Meanwhile, the thickness d at which interference occurs is proportional to the wavelength λ of the light that causes the interference phenomenon. Furthermore, the larger the integer m, the greater the thickness d at which interference occurs. Therefore, we first consider the interference phenomenon at a wavelength of 433 nm, which exhibits a relatively short, violet hue within the visible spectrum. The refractive index of a polycarbonate resin film at a wavelength of 433 nm is 1.608. At a wavelength of 433 nm, when the integer m increases to 22, the thickness d exceeds 3.0 μm, reaching 3.03 μm. When the integer m is 21, the thickness d at which interference occurs is 2.89 μm. Furthermore, when the integer value m is 23, the film thickness at which interference occurs is 3.16 μm. Furthermore, a film thickness d of 3.03 μm is 4.2% thinner than a film thickness d of 3.16 μm, and the difference between the two easily exceeds the 3.0% deviation in thickness of synthetic resin films. Therefore, the interference phenomenon that occurs when the integer value m is 22 does not overlap with the interference phenomenon that occurs when the integer value m is 23. For this reason, when the integer value m is 22 or greater, polycarbonate resin films cause interference with light rays with a wavelength of 433 nm. According to the above formula, the ratio of the film thickness at which interference occurs at integer value m to the film thickness at which interference occurs at integer value m-1, and the ratio of the film thickness at which interference occurs at integer value m+1, gradually decrease as the integer value m increases. Next, we consider the interference phenomenon in a polycarbonate resin film at a wavelength of 700 nm, which exhibits a relatively long red hue. The refractive index of a polycarbonate resin film at a wavelength of 700 nm is 1.576. When the integer value m is 33, the film thickness at which interference occurs is 7.44 μm. When the integer value m is 32, the film thickness at which interference occurs is 7.22 μm. When the integer value m is 34, the film thickness at which interference occurs is 7.66 μm. When the integer value m is 35, the film thickness at which interference occurs is 7.88 μm. The film thickness of 7.44 μm is 3.0% thicker than the film thickness of 7.66 μm, 3.0% thicker than the film thickness of 7.22 μm, and 2.9% thinner than the film thickness of 7.88 μm. Therefore, when the integer value m of a polycarbonate resin film is 34, the film thickness at which interference occurs exceeds 3.0 μm, which is 3.0% different from the film thickness at which interference occurs when the integer value m is 33, causing interference of light rays with a wavelength of 700 nm. Therefore, the maximum integer value m at which interference occurs in a polycarbonate resin film is 34. As explained above, when the thickness of a polycarbonate resin film is 3.0 μm or more and the thickness deviation is 3.0%, the polycarbonate resin film can be manufactured using the relationship d = (m + 1 / 2) / 2 · λ / n, where m is an integer between 22 and 34. Furthermore, the wavelength of the light that causes interference is used as λ in the relationship, and the refractive index of the polycarbonate resin film at the wavelength of the light that causes interference is used as n in the relationship, and the film thickness d that causes interference is calculated using the relationship. Using a polycarbonate resin film with this thickness d as the synthetic resin film described in paragraph 7 and continuously performing all four processing steps described in paragraph 7 constitutes a method for continuously producing a second interference film that emits light with relatively high saturation.

[0014] The method for continuously manufacturing an interference film according to paragraph 7 is a method for continuously manufacturing a third interference film that emits light with relatively high saturation, the method for continuously manufacturing the third interference film comprising: The synthetic resin film described in paragraph 7 is a film made of polystyrene resin, and the film thickness d of the film that causes the interference phenomenon of reflecting only light rays having a specific wavelength described in paragraph 7 is such that, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the polystyrene resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d that causes the interference phenomenon is 3.0 μm or more, and the difference between the two film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m-1) is a difference that is equal to or greater than the deviation in thickness of the polystyrene resin film, and the difference between the two film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m+1) is equal to or greater than the deviation in thickness of the polystyrene resin film, a second integer m that is a difference less than the deviation of the thickness of the film, is used as the integer m in the relational expression, the wavelength of the light that causes the interference phenomenon is used as λ in the relational expression, the refractive index of the polystyrene resin film at the wavelength of the light that causes the interference phenomenon is used as n in the relational expression, a film thickness d that causes the interference phenomenon and reflects only light having the wavelength specified by the relational expression is calculated, the polystyrene resin film having the film thickness d is used as the synthetic resin film described in paragraph 7, and all of the four steps described in paragraph 7 are continuously carried out to produce a third interference film that emits light with relatively high saturation.

[0015] In other words, like polycarbonate resin films, polystyrene resin films have a high total light transmittance of 88-89% and a low haze value of 0.3-0.4%, making them the second most transparent synthetic resin film after acrylic resin films. This makes them a third type of interference film, emitting light with high saturation. Furthermore, because graphene films have excellent transparency and are three orders of magnitude thinner than polystyrene resin films, bonding a graphene film to a polystyrene resin film does not inhibit the interference phenomenon caused by the polystyrene resin film. Here, the thickness of the polystyrene resin film is set to 3.0 μm or more, the thickness deviation is set to 3.0%, and the film thickness d at which the interference phenomenon occurs is considered. Using the equation d = (m + 1 / 2) / 2 · λ / n described in paragraph 9, we set the thickness d of a polystyrene resin film at which interference occurs to 3.0 μm, and determine the integer m at which the thickness d reaches 3.0 μm. We also set the deviation of the thickness d to 3.0%, and determine the integer m in the equation. Meanwhile, the thickness d at which interference occurs is proportional to the wavelength λ of the light that causes the interference. Furthermore, the larger the integer m, the greater the thickness d at which interference occurs. Therefore, we first consider interference at a wavelength of 433 nm, which exhibits a relatively short, violet hue within the visible spectrum. The refractive index of a polystyrene resin film at a wavelength of 433 nm is 1.612. At a wavelength of 433 nm, when the integer m increases to 22, the thickness d exceeds 3.0 μm, reaching 3.02 μm. When the integer m is 21, the thickness d at which interference occurs is 2.89 μm. Furthermore, when the integer value m is 23, the film thickness at which interference occurs is 3.16 μm. Furthermore, a film thickness d of 3.02 μm is 4.6% thinner than a film thickness d of 3.16 μm, and the difference between the two easily exceeds the 3.0% deviation in thickness of synthetic resin films. Therefore, the interference phenomenon that occurs when the integer value m is 22 does not overlap with the interference phenomenon that occurs when the integer value m is 23. For this reason, when the integer value m is 22 or greater, polystyrene resin films cause interference with light rays with a wavelength of 433 nm. According to the above formula, the ratio of the film thickness at which interference occurs at integer value m to the film thickness at which interference occurs at integer value m-1, and the ratio of the film thickness at which interference occurs at integer value m+1, gradually decrease as the integer value m increases. Next, we consider the interference phenomenon in a polystyrene resin film at a wavelength of 700 nm, which exhibits a relatively long red hue. The refractive index of a polystyrene resin film at a wavelength of 700 nm is 1.582. When the integer value m is 34, the film thickness at which interference occurs is 7.63 μm. When the integer value m is 33, the film thickness at which interference occurs is 7.41 μm. When the integer value m is 35, the film thickness at which interference occurs is 7.85 μm. When the integer value m is 35, the film thickness at which interference occurs is 7.88 μm. The film thickness of 7.63 μm is 3.0% thicker than the film thickness of 7.41 μm and 2.9% thinner than the film thickness of 7.85 μm. Therefore, when the integer value m is 34, the film thickness at which interference occurs exceeds 3.0 μm, which is 3.0% different from the film thickness at which interference occurs when the integer value m is 33, causing interference of light with a wavelength of 700 nm. Therefore, the maximum integer value m at which the polystyrene resin film causes interference is 34. As explained above, when the thickness of a polystyrene resin film is 3.0 μm or more and the thickness deviation is 3.0%, the polystyrene resin film satisfies the relationship d = (m + 1 / 2) / 2 · λ / n, where m is an integer between 22 and 34. Furthermore, the wavelength of the light that causes the interference phenomenon is used as λ in the relationship, and the refractive index of the polystyrene resin film at the wavelength of the light that causes the interference phenomenon is used as n in the relationship, and the film thickness d that causes the interference phenomenon is calculated using the relationship. Using a polystyrene resin film with this thickness d as the synthetic resin film described in paragraph 7 and continuously performing all four processing steps described in paragraph 7 constitutes a method for continuously producing a third interference film that emits light with relatively high saturation.

[0016] The method for continuously manufacturing an interference film according to paragraph 7 is a method for continuously manufacturing a fourth interference film that emits light with relatively high saturation, the method for continuously manufacturing the fourth interference film comprising: The synthetic resin film described in paragraph 7 is a film made of polyethylene terephthalate resin, and the film thickness d of the film that causes the interference phenomenon of reflecting only light rays having a specific wavelength described in paragraph 7 is such that, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the polyethylene terephthalate resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d that causes the interference phenomenon is 3.0 μm or more, and the difference between the two film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m-1) is a difference that is equal to or greater than the deviation in thickness of the polyethylene terephthalate resin film, and the difference between the two film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m+1) is equal to or greater than the deviation in thickness of the polyethylene terephthalate resin film, a second integer m having a difference less than the deviation in thickness of the polyethylene terephthalate resin film, a wavelength of a light ray causing an interference phenomenon being used as λ in the relational expression, a refractive index of the polyethylene terephthalate resin film at the wavelength of the light ray causing the interference phenomenon being used as n in the relational expression, a thickness d of a film causing an interference phenomenon that reflects only light rays having the wavelength specified by the relational expression being determined, the polyethylene terephthalate resin film having the thickness d is used as the synthetic resin film described in paragraph 7, and all of the four steps described in paragraph 7 are continuously carried out to form a fourth method for continuously producing an interference film that emits light rays with relatively high saturation.

[0017] In other words, polyethylene terephthalate resin films have a high total light transmittance of 87-88% and a low haze value of 1-2%, making them the third most transparent synthetic resin film after polycarbonate resin and polystyrene resin films. This makes them the fourth type of interference film, emitting light with high saturation. Furthermore, because graphene films have excellent transparency and are three orders of magnitude thinner than polyethylene terephthalate resin films, bonding a graphene film to a polyethylene terephthalate resin film does not inhibit the interference phenomenon caused by the polyethylene terephthalate resin film. Generally, amorphous polymers are transparent. In contrast, semi-crystalline or crystalline polymers are translucent or opaque due to the difference in refractive index between the crystalline and amorphous regions. On the other hand, polyethylene terephthalate resin is a crystalline polymer, but films made from polyethylene terephthalate resin are biaxially oriented films stretched in two directions, so the polymer molecules are oriented in the plane of the film. This orientation prevents light from refracting when it passes through the film, making it transparent. Here, the thickness of the polyethylene terephthalate resin film is set to 3.0 μm or more, the thickness deviation is set to 3.0%, and the film thickness d at which the interference phenomenon occurs is considered. As described in paragraph 9, in the relational equation where d = (m+1 / 2) / 2·λ / n holds, the integer value m in the relational equation is an integer value m ranging from a first integer value to a second integer value, where m is a first integer value such that the film thickness d causing the interference phenomenon is 3.0 μm or more, and m is a second integer value m such that the difference between the film thicknesses d caused by the integer value m and the integer value (m-1) causing the interference phenomenon is greater than or equal to the deviation in thickness of the synthetic resin film and the difference between the film thicknesses d caused by the integer value m and the integer value (m+1) is less than the deviation in thickness of the synthetic resin film. Here, for polyethylene terephthalate resin films, the film thickness d at which interference occurs is 3.0 μm or greater is determined using the equation d = (m + 1 / 2) / 2 · λ / n described in paragraph 9. The film thickness d at which interference occurs is proportional to the wavelength λ of the light that causes interference. Furthermore, the larger the integer value m, the greater the film thickness d at which interference occurs. Therefore, we consider interference at a wavelength of 433 nm, which exhibits a relatively short violet hue among visible light. The refractive index of polyethylene terephthalate resin films at a wavelength of 433 nm is 1.677. At a wavelength of 433 nm, when the integer value m increases to 23, the film thickness d exceeds 3.0 μm, reaching 3.03 μm. When the integer value m is 22, the film thickness d at which interference occurs is 2.90 μm. When the integer value m is 24, the film thickness at which interference occurs is 3.16 μm. A film thickness d of 3.03 μm is 4.5% thicker than a film thickness d of 2.90 μm, and the difference between the two easily exceeds the 3.0% deviation in thickness of synthetic resin films. Therefore, the interference phenomenon that occurs when the integer value m is 23 does not overlap with the interference phenomenon that occurs when the integer value m is 22. For this reason, when the integer value m is 23 or greater, polyethylene terephthalate resin films cause interference of light with a wavelength of 433 nm. According to the above formula, the ratio of the film thickness at which interference occurs at integer value m to the film thickness at which interference occurs at integer value m-1, and the ratio of the film thickness at which interference occurs at integer value m+1, gradually decrease as the integer value m increases. On the other hand, the refractive index of polyethylene terephthalate resin film for the 700 nm wavelength, which exhibits a relatively long red hue, is 1.630. When the integer value m is 34, the film thickness at which interference occurs is 7.41 μm; when the integer value m is 33, the film thickness at which interference occurs is 7.19 μm; and when the integer value m is 35, the film thickness at which interference occurs is 7.62 μm. The film thickness of 7.41 μm is 3.1% thicker than the film thickness of 7.19 μm and 2.8% thinner than the film thickness of 7.62 μm. Therefore, when the integer value m is 34, the film thickness at which interference occurs exceeds 3.0 μm, which is more than 3.0% different from the film thickness at which interference occurs when the integer value m is 33, causing interference of light with a wavelength of 700 nm. Therefore, the maximum integer value m at which polyethylene terephthalate resin film exhibits interference is 34. As explained above, when the thickness of a polyethylene terephthalate resin film is 3.0 μm or more and the thickness deviation is 3.0%, the relationship d = (m + 1 / 2) / 2 · λ / n holds true, and the integer m in the range of 23-34 can be used as the integer m. Furthermore, the wavelength of the light that causes the interference phenomenon is used as λ in the relationship, and the refractive index of the polyethylene terephthalate resin film at the wavelength of the light that causes the interference phenomenon is used as n in the relationship, and the film thickness d that causes the interference phenomenon is calculated using the relationship. Using a polyethylene terephthalate resin film with this thickness d as the synthetic resin film described in paragraph 7 and continuously performing all four processing steps described in paragraph 7 constitutes a method for continuously producing a fourth interference film that emits light with relatively high saturation.

[0018] The method for continuously producing an interference film as described in paragraph 7 comprises: The method for continuously producing an interference film according to paragraph 7 is a method in which the alcohol having the three properties described in paragraph 7 is any one of ethanol, 1-propanol, and 2-propanol, and the method uses the alcohol having the three properties described in paragraph 7 and continuously carries out all of the four steps described in paragraph 7.

[0019] In other words, the boiling point described in paragraph 7 is 100°C or less, and the density at 20°C is 0.80 g / cm 3 Below, alcohols that have a viscosity of 1-2 mPa·sec at 20°C and possess all three properties include ethanol, 1-propanol, and 2-propanol. Therefore, if any of these alcohols is used as the alcohol that possesses the three properties described in paragraph 7 and all four steps described in paragraph 7 are performed consecutively, the interference film described in paragraph 7 can be continuously produced. That is, ethanol CH3CH2OH has a boiling point of 78°C and a density of 0.789 g / cm at 20°C. 3 and its viscosity at 20°C is 1.20 mPa·sec. Therefore, ethanol is an alcohol that possesses all three of the properties described in paragraph 7. 1-propanol CH3(CH2)2OH has a boiling point of 98°C and a density of 0.803 g / cm at 20°C. 3 and its viscosity at 20°C is 1.94 mPa·sec. Therefore, 1-propanol is an alcohol that possesses all three of the properties described in paragraph 7. 2-Propanol (CH3)2CH(OH) has a boiling point of 82°C and a density of 0.785 g / cm at 20°C. 3 and its viscosity at 20°C is 2.37 mPa·sec. Therefore, 1-propanol is an alcohol that possesses all three of the properties described in paragraph 7. All three of these alcohols are general-purpose alcohols.

[0020] A method for continuously manufacturing an interference film by the method described in paragraph 7, cutting a part of the interference film into the shape of the surface of a substrate, and bonding the cut interference film to the surface of the substrate to form a new substrate in which the interference phenomenon caused by the interference film continues, comprising: the method of continuously manufacturing an interference film according to paragraph 7, cutting a portion of the interference film into the shape of the surface of a substrate having a thickness at least 10 times that of the interference film, superimposing the cut interference film on the surface of the substrate, and further superimposing a plate-shaped jig having the shape of the cut interference film on the surface of the cut interference film, and uniformly compressing the entire plate-shaped jig with a compressor, thereby bringing the surface of the interference film into contact with the convex portions of the uneven surface of the substrate, generating frictional heat in the convex portions, which bonds the convex portions to the surface of the interference film due to the frictional heat, and bonding the cut interference film to the surface of the substrate, and then separating the plate-shaped jig from the interference film, thereby forming the substrate as a new substrate in which the interference phenomenon caused by the interference film continues; A method for continuously manufacturing an interference film by the method described in paragraph 7, cutting a portion of the interference film into the shape of the surface of a substrate, and bonding the cut interference film to the surface of the substrate to form a new substrate in which the interference phenomenon caused by the interference film continues.

[0021] That is, although graphene has a large shear modulus of 440 GPa, the graphene film is extremely thin, less than 2 nm, so it can be cut. Therefore, the interference film manufactured by the method described in paragraph 7 can also be cut. This allows a portion of the manufactured interference film to be cut into interference films of various sizes and shapes. The surface of the interference film is composed of a graphene film. The graphene film has extremely smooth surfaces, with only slight steps of 0.332 nm, equivalent to the thickness of graphene. In contrast, the surface of the substrate has submicron irregularities. Therefore, the interference film is cut to the shape of the substrate surface, and the cut interference film is superimposed on the surface of the substrate. A plate-shaped jig with the shape of the cut interference film is then superimposed on the surface of the cut interference film, and the entire plate-shaped jig is evenly compressed using a compressor. As a result, the graphene film constituting the surface of the interference film comes into contact with the convex portions of the substrate surface irregularities, generating frictional heat at these convex portions. This frictional heat bonds the convex portions to the surface of the superimposed graphene film. Meanwhile, because the convex portions of the substrate surface irregularities are spaced at submicron intervals, there are an enormous number of convex portions. Therefore, graphene with an extremely high aspect ratio bonds to the extremely large number of convex portions spaced at submicron intervals, resulting in a strong bond of the graphene film to the entire surface of the substrate. After this, the plate-shaped jig is removed from the interference film. The frictional heat generated in the convex portions on the surface of the substrate is generated in a short time and dissipates in a short time. Furthermore, the volume of the convex portions where the frictional heat is generated is extremely small. Therefore, even if the substrate is made of a material with low heat resistance, such as synthetic resin, the interference film can be joined to the surface of the substrate by friction welding. As a result, a substrate with a thickness 10 times or more that of the interference film is bonded to the interference film, making the interference film easier to handle. Furthermore, because the thickness of the substrate is 10 times or more that of the interference film, the substrate bonded to the interference film does not impede the interference phenomenon of the interference film. This allows the interference phenomenon caused by the interference film to continue. Note that although the convex portions of the uneven surface of the substrate undergo slight plastic deformation, the synthetic resin film does not undergo plastic deformation, so the interference phenomenon caused by the synthetic resin film continues.

[0022] According to the method described in paragraph 7, a method for continuously manufacturing a plurality of interference films that emit light rays of different hues, and using the plurality of interference films to form a new interference film that emits a light beam that is a mixture of a plurality of light rays of different hues, includes the steps of: According to the method described in paragraph 7, a plurality of interference films that cause an interference phenomenon in which light rays of different hues are reflected are continuously produced, portions of the plurality of interference films are cut into a predetermined shape, the cut interference films are brought close to each other and arranged on the entire surface of a substrate having a thickness at least 10 times that of the interference films, a plate-shaped jig having the shape of the surfaces of the plurality of interference films arranged on the entire surface of the substrate is then superimposed on the surfaces of the plurality of interference films, and the entire plate-shaped jig is uniformly compressed by a compressor, thereby bringing the surfaces of the plurality of interference films into contact with the convex portions of the uneven surface of the substrate, generating frictional heat in the convex portions, which bonds the convex portions to the surfaces of the plurality of interference films and the plurality of interference films to the surface of the substrate, and then the plate-shaped jig is separated from the plurality of interference films, thereby forming a new interference film on the surface of the substrate that emits a light beam that is a mixture of light rays of different hues emitted by the plurality of interference films. A new method for forming interference films that emit a mixture of light beams of different hues.

[0023] That is, multiple interference films that emit light beams of different hues are cut into a predetermined shape, and the cut pieces are brought close to each other and bonded to the entire surface of a substrate that is at least 10 times thicker than the interference films, forming a new interference film on the substrate that emits a light beam that is a mixture of multiple light beams of different hues. On the other hand, since the multiple interference films emit light rays of different hues, each interference film has a different thickness. Therefore, to bond the multiple interference films brought close together to the surface of a substrate, a plate-shaped jig having the same surface shape as the multiple interference films brought close together is prepared. This plate-shaped jig is then placed over the multiple interference films brought close together, and the entire plate-shaped jig is evenly compressed using a compressor. As a result, the graphene films constituting the surfaces of the multiple interference films brought close together come into contact with the convex portions of the uneven surface of the substrate, generating frictional heat at these convex portions, which bonds the convex portions to the surfaces of the overlapping graphene films. On the other hand, since the convex portions of the uneven surface of the substrate are formed at submicron intervals, there are an enormous number of convex portions. Therefore, graphene with an extremely high aspect ratio bonds to the extremely large number of convex portions spaced at submicron intervals, and the graphene film is firmly bonded to the entire surface of the substrate. The plate-shaped jig is then separated from the interference films. As a result, the multiple interference films brought close together are bonded to the substrate. Furthermore, because the thickness of the substrate is more than 10 times that of the interference films, the substrate does not inhibit the interference phenomenon of the multiple interference films, and the interference phenomenon of the multiple interference films continues even after the multiple interference films are bonded to the substrate. Therefore, a light beam that is a mixture of light beams of different hues emitted by each interference film is emitted from the substrate. For example, if an interference film emitting light beams of blue hue and an interference film emitting light beams of red hue are brought close together and bonded to the entire surface of the substrate, the light beams of blue hue and red hue are mixed, and a light beam of reddish-purple hue is emitted from the new interference film formed by bonding multiple interference films together. Furthermore, if the width of the interference film emitting light beams of blue hue is made wider than the width of the interference film emitting light beams of red hue, and the same number of the two types of interference films are placed close together in a staggered manner and bonded to the surface of the substrate, a light beam of reddish-purple hue with a darker blue hue is emitted from the new interference film formed by bonding multiple interference films together.Conversely, if the width of the interference film that emits light of a blue hue is made narrower than the width of the interference film that emits light of a red hue, and the same number of two types of interference films are placed close to each other and bonded to the surface of a substrate, a light beam of a reddish-purple hue with a deep red hue will be emitted from the new interference film made up of multiple bonded interference films.Similarly, if three types of interference films that emit light of different hues are placed close to each other and bonded to the surface of a substrate, a light beam that is a mixture of the three hues will be emitted from the substrate. To this end, the hue of the light beam emitted from the new interference film is predetermined, and the intensity of the light beams of different hues emitted by each interference film that realizes this hue is determined. Next, individual interference films emitting light beams of different hues are created according to the method described in paragraph 7. The width of each interference film is changed according to the intensity of the light beams of different hues, and each interference film is cut into a shape that can be bonded to the surface of a substrate. The cut individual interference films are then placed on the surface of the substrate, closely spaced so that adjacent interference films emit light beams of different hues. Multiple interference films are then bonded to the substrate. As a result, a substrate having a thickness at least 10 times that of the interference film is bonded to the interference film, making the interference film easier to handle. Furthermore, because the thickness of the substrate is at least 10 times that of the interference film, the substrate bonded to the interference film does not interfere with the interference phenomenon of the interference film. As a result, light beams of the predetermined hues are emitted from the substrate. Furthermore, for three types of interference films that emit the three primary colors of light—red, green, and blue—the intensity of each light ray consisting of the three hues emitted from a new interference film formed by joining the three types of interference films is determined in advance. Next, the widths of the three types of interference films are changed according to the intensity of each light ray consisting of the three hues, and the three types of interference films are cut into a shape that can be joined to the surface of a substrate. The three cut interference films are then placed on the surface of the substrate, close together so that adjacent interference films emit light rays consisting of different hues. The three types of interference films are then joined to the substrate. As a result, the light rays of the three hues emitted from the three types of interference films are mixed. Therefore, by combining the intensities of the light rays of the three hues in various intensities, light rays of almost all hues can be emitted from the new interference film. That is, the hue of the light emitted from the new interference film formed by joining three types of interference films is determined in advance, the intensities of the three types of light are determined in advance accordingly, the widths of the three types of interference films are changed according to the intensities of the three types of light, the three types of interference films are cut into a shape that can be joined to the surface of a substrate, the three cut interference films are placed on the surface of the substrate so that adjacent interference films emit light of different hues, and when the three types of interference films are joined to the surface of the substrate, the substrate emits light of the desired hue. As a result, the range of hues emitted by the new interference film formed by joining three types of interference films is extremely wide. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is an enlarged cross-sectional view of an interference film in which the entire surface of a polyethylene terephthalate resin film is covered with a graphene film, schematically illustrating the configuration of the interference film. DETAILED DESCRIPTION OF THE INVENTION

[0025] Example 1 In this example, a suspension consisting of graphene aggregates in which the flat surfaces of graphene overlap each other via alcohol is prepared in the first step described in paragraph 7. The alcohol used has a boiling point of 78°C and a density of 0.789 g / cm at 20°C. 3 Ethanol with a viscosity of 1.20 mPa·sec at 20°C was used. Furthermore, flake graphite particles were used. First, 10 liters of ethanol was filled into a 40 cm x 40 cm x 6 cm (depth) container. Next, two parallel plate electrodes with an effective electrode area of ​​38 cm x 38 cm, where an electric field was generated in the gap between the two parallel plate electrodes, were prepared. 1500 g of flake graphite particles (e.g., XD100 from Ito Graphite Industries Co., Ltd.) were evenly spread on the surface of one of the parallel plate electrodes. Then, one of the parallel plate electrodes was placed in the container, and the flake graphite particle cluster spread on the first parallel plate electrode was immersed in ethanol. The other parallel plate electrode was then placed on top of the first parallel plate electrode, with the flake graphite particle cluster between them, and the entire surface of the other parallel plate electrode was compressed, leaving a gap of 100 μm between the two parallel plate electrodes. Specifically, to destroy the interlayer bonds of the graphite crystals that form the graphite particles and precipitate graphene clusters in the gap between the two parallel flat electrodes, the two overlapping parallel flat electrodes with the graphite particle cluster sandwiched between them were immersed in an insulating liquid, ethanol. The weight of the ethanol was set to 5.3 times the weight of the graphite particle cluster, and the graphite particle cluster spread between the two parallel flat electrodes was immersed in ethanol. An electric field was applied to the graphite particle cluster, destroying all interlayer bonds of the graphite crystals that form the graphite particles simultaneously. Next, a 12-kilovolt DC voltage was applied between two parallel-plate electrodes, simultaneously destroying all interlayer bonds between the graphite crystals that form the graphite particles, resulting in the deposition of graphene aggregates in the gap between the two parallel-plate electrodes. The gap between the two parallel-plate electrodes was then enlarged, and the two parallel-plate electrodes were tilted in ethanol. An impact acceleration of 0.3 G was applied to the two parallel-plate electrodes three times. The two parallel-plate electrodes were then removed from the container. An ultrasonic homogenizer (Yamato Scientific Co., Ltd., LUH300) was then operated to apply 20 kHz ultrasonic vibrations for two minutes. Then, vibration accelerations of 0.4 G in three directions (front-to-back, left-to-right, and up-to-down) were applied five times to the container, creating a suspension of graphene aggregates in which the flat surfaces of the graphene overlap each other through the ethanol.

[0026] Example 2 In this example, the treatment in the second step described in paragraph 7 is carried out. First, a new container was prepared and filled with the suspension prepared in Example 1. The new container had a width of 42 cm, a length equivalent to the vertical width of 35 cm, and a depth of 9 cm. Eight cylindrical rollers, each 2 cm in diameter, were installed in parallel and spaced apart from each other at the positions shown below. In addition, a drawing device for drawing out a roll of material wrapped with a synthetic resin film was installed at the top of one side of the container so that the synthetic resin film drawn from the roll of material would be at a height that would contact the first roller. The first roller was positioned so that its center was 3 cm from one side of the container and at the top edge of the container, and protruded 1 cm beyond the container. The second roller was positioned so that its center was 5 cm from one side of the container and 2 cm from the bottom. The seventh roller was positioned so that its center was 5 cm from the other side of the container opposite the second roller and 2 cm from the bottom, just like the second roller. The centers of the third through sixth rollers were all 2 cm from the bottom of the container, just like the second and seventh rollers, and were spaced 3 cm apart from the second and seventh rollers. The eighth roller was positioned at the top of the container, like the first roller, with its center 3 cm away from the other side of the container opposite the first roller, and it extended outside the container by 1 cm in height, the height of the eighth roller.

[0027] Example 3 This example is the first example in which the treatment in the third step described in paragraph 7 is carried out. The synthetic resin film drawn from the roll comes into contact with multiple cylindrical rollers placed inside the container in turn, and moves continuously through the suspension at a constant speed, causing the suspension to adhere to the entire surface of the synthetic resin film at a constant thickness.The film with the suspension adsorbed to it then moves toward the gap between the two work rolls of the multi-stage rolling mill used in the fourth process. The synthetic resin film used was a polyethylene terephthalate resin film with a thickness of 3.0 μm and a width of 40 cm. The polyethylene terephthalate resin film was placed in a roll-up device and continuously drawn out at the same rotational speed as the two work rolls of the 12-high rolling mill used in the fourth process. The leading edge of the drawn film contacted the top of the first roller, then contacted the side of the first roller and moved along the side approximately one-quarter of the way up the first roller. The leading edge then changed direction and continued downward, immersed in the suspension, and then contacted the side of the second roller. After contacting the side of the second roller, the leading edge then contacted the side of the second roller and moved along the side approximately one-quarter of the way up the second roller. Then, the leading edge then changed direction and continued parallel to the bottom of the new container, contacting the sides of the third through sixth rollers in order. The leading edge of the film, which has contacted the sides of the four rollers in turn, moves through the suspension and comes into contact with the side of the seventh roller. After contacting the side of the seventh roller, the leading edge moves along the side of the seventh roller approximately one-quarter of the way up, then changes direction and moves upward, rising from the suspension and coming into contact with the side of the eighth roller. After contacting the side of the eighth roller, the leading edge of the film moves along the side of the eighth roller approximately one-quarter of the way up, then changes direction and moves toward the gap between the two work rolls that make up the multi-high rolling mill used in the fourth process.

[0028] Example 4 This example is the first example in which the treatment in the fourth step described in paragraph 7 is carried out. First, a 12-high rolling mill was prepared, with two work rolls that were 42 cm wide, 4 cm in diameter, and set to a gap of 2.7 μm, rotating in opposite directions with a rotation time of 20 seconds, and heated to 88°C, 10°C higher than the boiling point of ethanol. Next, the leading edge of the film that had completed the third process was inserted into the gap between the two work rolls, causing the leading edge of the film to be drawn into the gap, and the film was continuously subjected to compressive stress from the two work rolls. The film, in which the graphene film covered the entire surface of the polyethylene terephthalate resin film, was continuously discharged from the gap between the two work rolls, and the discharged film was continuously wound up by a winding machine that rotated at the same rotational speed as the two work rolls.

[0029] Example 5 In this example, the film prepared in Example 4 was analyzed and evaluated. The prepared film was cut into five pieces with a length of 50 cm, and the cut films were analyzed. First, the cross section of the cut film was observed using an electron microscope. An ultra-low accelerating voltage SEM from JFE Techno-Research Corporation was used as the electron microscope. This device is capable of surface observation at ultra-low accelerating voltages starting from 100 volts, and has the advantage of being able to directly observe the surface of a sample without forming a conductive coating on the sample. The film was 3.0 μm thick. Next, secondary electron beams between 900-1000 volts of the reflected electron beam from the cross section were extracted and image processed. Six very thin flat powders were layered on top and bottom of the 3.0 μm organic material, forming a thickness of 2 nm, and the collection of flat powders covered the entire organic material. Furthermore, the energy and intensity of the characteristic X-rays were image processed, and the elements that make up the flat powder were analyzed. As a result, it was determined that the flat powder was carbon. Therefore, the created film consisted of six graphene flat surfaces overlapping and bonding to form a graphene film, which covered the entire surface of the polyethylene terephthalate resin film. Figure 1 shows an enlarged schematic cross-section of the film. 1 is the flat surface of the graphene film, and 2 is the polyethylene terephthalate resin film. Therefore, an interference film whose surface is covered with a graphene film does not deteriorate even when exposed to ultraviolet rays for a long period of time because the ultraviolet rays cannot penetrate the inside of the interference film. Furthermore, the interference film does not change over time even when exposed to the outdoors for a long period of time. Furthermore, the interference film has excellent electrical conductivity, excellent thermal conductivity, non-flammability, and excellent corrosion resistance, being unreactive with acids and alkalis. Next, a portion of the cut film was immersed in water, and then the film was removed from the water and the surface was observed. Several water droplets were present on the surface, and when the film was tilted, the water droplets easily fell off. This gave the film surface water repellency and antifouling properties. Therefore, foreign matter did not adhere to the surface of the interference film, and the interference film continued to exhibit interference phenomena for a long period of time. Furthermore, the tensile strength of a cut portion of the film was tested in accordance with JIS C6515, a copper foil testing method for printed wiring boards, and was found to be 600±50 MPa. This value is greater than the tensile strength of 450 MPa of a 12 μm thick copper foil made by low-roughness rolling tough-pitch copper, and therefore the film was found to have sufficient mechanical strength. Next, the spectral reflectance of the interference film was measured using a spectrophotometer (CM-700d, manufactured by Konica Minolta Japan, Inc.). The results showed that the interference film reflected light with a wavelength of 433 nm, which emits a purple color.

[0030] Example 6 This example is a second example in which the treatment in the third step described in paragraph 7 is carried out. In Example 3, a polyethylene terephthalate resin film having a thickness of 3.0 μm and a width of 40 cm was used as the synthetic resin film, but in this example, a polyethylene terephthalate resin film having a thickness of 7.0 μm and a width of 40 cm is used. As in Example 3, a roll of polyethylene terephthalate resin film was placed in a roll-pulling device, and the film was continuously pulled out at the same rotational speed as the two work rolls of the 12-high rolling mill used in the fourth process. The leading edge of the pulled film contacted the top of the first roller, then contacted the side of the first roller and moved along the side of the first roller approximately one-quarter of the way around. The leading edge then changed direction and continued downward, immersed in the suspension, and contacted the side of the second roller. After contacting the side of the second roller, the leading edge then contacted the side of the second roller and moved along the side of the second roller approximately one-quarter of the way around. Then, the leading edge then changed direction and continued parallel to the bottom of the new container, contacting the sides of the third through sixth rollers in sequence. After contacting the sides of the four rollers in sequence, the leading edge of the film continued through the suspension and contacted the side of the seventh roller. The leading edge of the film that has come into contact with the side of the seventh roller moves along the side of the seventh roller approximately one-quarter of the way, then changes direction of movement upward, continues moving, and after being pulled up from the suspension, comes into contact with the side of the eighth roller. The leading edge of the film that has come into contact with the side of the eighth roller comes into contact with the eighth roller and moves along the side of the eighth roller approximately one-quarter of the way, then changes direction of movement toward the gap between the two work rolls that make up the multi-stage rolling mill used in the fourth step.

[0031] Example 7 This example is a second example in which the treatment in the fourth step described in paragraph 7 is carried out. The thickness of the polyethylene terephthalate resin film used in Example 6 was 7.0 μm, while the thickness of the polyethylene terephthalate resin film used in Example 3 was 3.0 μm. A 12-high rolling mill was prepared, with two work rolls each 42 cm wide, 4 cm in diameter, and set to a gap of 6.3 μm, rotating in opposite directions at a rate of 20 seconds per rotation, and heated to 88°C, 10°C higher than the boiling point of ethanol. Next, the leading end of the film that had been treated in Example 6 was inserted into the nip between the two work rolls. As a result, the leading end of the film was drawn into the nip between the two work rolls, and the film was continuously subjected to compressive stress from the two work rolls. A film in which the graphene film covered the entire surface of the polyethylene terephthalate resin film was continuously discharged from the nip between the two work rolls, and the discharged film was continuously wound up by a winder that rotated at the same rotational speed as the two work rolls.

[0032] Example 8 In this example, the film prepared in Example 7 was analyzed and evaluated. The prepared film was cut into five pieces with a length of 50 cm, and the cut films were analyzed. First, the cross section of the cut film was observed under an electron microscope, as in Example 5. The film thickness was 7.0 μm. Next, secondary electron beams between 900 and 1000 volts, reflected from the cross section, were extracted and image-processed. Six very thin flat powders were stacked on top of and below the 7.0 μm organic material, forming a thickness of 2 nm, and the collection of flat powders covered the entire organic material. Furthermore, the energy and intensity of the characteristic X-rays were image-processed, and the elements that made up the flat powders were analyzed. As a result, it was determined that the flat powders were carbon. Therefore, the film created was made up of six graphene flat surfaces overlapping and bonding together, and the graphene film made up of six graphene flat surfaces bonded together covered the entire surface of the polyethylene terephthalate resin film. Therefore, an interference film whose surface is covered with a graphene film does not deteriorate even when exposed to ultraviolet rays for a long period of time because the ultraviolet rays cannot penetrate the inside of the interference film. Furthermore, the interference film does not change over time even when exposed to the outdoors for a long period of time. Furthermore, the interference film has excellent electrical conductivity, excellent thermal conductivity, non-flammability, and excellent corrosion resistance, being unreactive with acids and alkalis. Next, a portion of the cut film was immersed in water, and after the film was pulled out of the water, the surface was observed and several water droplets were found on the surface. When the film was tilted, the water droplets easily fell off, indicating that the surface of the film is water-repellent and antifouling. Therefore, foreign matter does not adhere to the surface of the interference film, and the interference phenomenon continues for a long period of time. Furthermore, the tensile strength of a cut portion of the film was tested in accordance with JIS C6515, a copper foil testing method for printed wiring boards, and was found to be 600±50 MPa. This value is greater than the tensile strength of 450 MPa of a 12 μm thick copper foil made by low-roughness rolling tough-pitch copper, and therefore the film was found to have sufficient mechanical strength. Next, the spectral reflectance of the interference film was measured using the spectrophotometer used in Example 5. As a result, it was found that the interference film reflected light having a wavelength of 700 nm, which emits a red color.

[0033] Example 9 In this example, each of the two types of interference films prepared in Examples 4 and 7 was cut into five films measuring 2 cm x 20 cm, and five of the cut interference films were arranged closely together on the surface of a 20 cm x 20 cm x 100 μm (thickness) film made of high-density polyethylene resin. Next, a metal plate having the same surface shape as the collection of cut interference films was prepared, and the metal plate was placed on top of the collection of cut interference films. A compressive load equivalent to 50 kg was applied evenly to the entire surface of the metal plate, and the collection of cut interference films was friction-welded to the film made of high-density polyethylene resin. Next, the spectral reflectance of the interference film was measured using the spectrophotometer used in Example 5. As a result, it was found that the film reflected light having a wavelength of 433 nm and light having a wavelength of 700 nm. Therefore, the interference film produced emits a light beam that is a mixture of light beams having two different hues, resulting in an interference film that emits light beams consisting of reddish purple.

[0034] The above describes a method for continuously manufacturing an interference film in which the entire surface of a synthetic resin film, which has a thickness that causes an interference phenomenon in which only light of a specific wavelength is reflected, is covered with a graphene film having a thickness of 2 nm or less and a total light transmittance of 85% or more, using a polyethylene terephthalate resin film as an example. The synthetic resin interference film is not limited to a polyethylene terephthalate resin film. As described in paragraphs 10-17, an interference film that emits light with high saturation can be formed by using an acrylic resin film, a polycarbonate resin film, a polyurethane resin film, or a polyethylene terephthalate resin film that has a total light transmittance of 85% or more and a haze value of less than 2%. In other words, as explained in paragraph 9, the thickness d of a synthetic resin film having a thickness that causes an interference phenomenon that reflects only light rays of a specific wavelength is, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the synthetic resin film at the wavelength of the light rays, and m is an integer value, the first integer value m at which the thickness d of the film that causes the interference phenomenon is 3.0 μm or more, and the difference between the thicknesses d of both the integer value m and the integer value (m-1) that cause the interference phenomenon is the thickness of the synthetic resin film. The relational expression uses an integer m ranging from a first integer value to a second integer value, where m is the wavelength of the light beam that causes the interference phenomenon, and n is the refractive index of the synthetic resin film at the wavelength of the light beam that causes the interference phenomenon. Therefore, by changing the wavelength λ of the specified light beam according to the hue of the light beam that causes the interference phenomenon, the thickness d of the synthetic resin film changes. Therefore, the hue of the interference phenomenon can be freely changed with the interference film. [Explanation of symbols]

[0035] 1. Graphene film 2. Polyethylene terephthalate resin film

Claims

1. A method for continuously producing an interference film having a configuration in which the entire surface of a synthetic resin film having a thickness that causes an interference phenomenon in which only light rays having a specific wavelength are reflected is covered with a graphene film having a thickness of 2 nm or less and a total light transmittance of 85% or more, the method comprising: One of two parallel flat electrode plates is placed in a container that is wider than the width of the interference film to be produced and has a length and depth sufficient to accommodate a plurality of cylindrical rollers described below. The weight of the cluster of flake graphite particles or the weight of the cluster of lump graphite particles required according to the width, thickness, and length of graphene films to be joined by friction welding to the entire surfaces of both sides of a synthetic resin film is determined in advance, and the cluster of graphite particles having this weight is spread evenly on the surface of one of the parallel flat electrode plates. Furthermore, a substrate having a boiling point of 100°C or less and a density at 20°C of 0.80 g / cm is used. ３ The method comprises weighing out an alcohol having a viscosity of 1-2 mPa·sec at 20°C in an amount at least five times the weight of the graphite particle cluster, filling the container with the weighed alcohol, immersing the graphite particle cluster in the alcohol, and then placing the other parallel plate electrode on top of the one parallel plate electrode via the graphite particle cluster, compressing the entire surface of the other parallel plate electrode, and setting the gap between the two parallel plate electrodes to a predetermined gap, whereby the two parallel plate electrodes are separated by the predetermined gap via the graphite particle cluster, and the two parallel plate electrodes are immersed in the alcohol. Thereafter, a direct current potential difference having a predetermined magnitude is applied to the gap between the two parallel plate electrodes, whereby an electric field corresponding to the value obtained by dividing the magnitude of the potential difference by the size of the gap between the two parallel plate electrodes is applied to the collection of graphite particles, and the application of the electric field simultaneously applies a Coulomb force sufficient to destroy the interlayer bonds between the basal planes of the graphite crystals to all of the collection of graphite particles, to all of the π electrons that are responsible for the interlayer bonds between the basal planes that form the graphite particles, whereby all of the interlayer bonds between the basal planes that form the graphite particles are simultaneously destroyed, and collections of graphene corresponding to the basal planes are precipitated in the gap between the two parallel plate electrodes. Thereafter, the gap between the two parallel-plate electrodes is enlarged, the two parallel-plate electrodes are tilted in the alcohol, and further, an impact acceleration of 0.2 to 0.4 G depending on the size of the two parallel-plate electrodes is repeatedly applied to the two parallel-plate electrodes to move the graphene clusters from the gap between the two parallel-plate electrodes into the alcohol, and then the two parallel-plate electrodes are removed from the container. Furthermore, an ultrasonic homogenizer is operated in the alcohol in the container, and shock waves are continuously applied to the graphene aggregates through the alcohol, whereby the graphene aggregates are separated into individual graphene sheets in the alcohol, and the separated graphene aggregates are dispersed in the alcohol, and thereafter the ultrasonic homogenizer is removed from the container. a first step of repeatedly applying vibration accelerations of 0.3 to 0.5 G in three directions, i.e., forward / backward, left / right, and up / down, to the container depending on the size of the container, thereby forming a suspension made of an aggregate of graphene in which flat surfaces of the graphene overlap each other via the alcohol; A new container is prepared that has the first feature that the width of the container is wider than the width of the synthetic resin film used in the third step, the second feature that a drawing device that draws out the roll of material around which the synthetic resin film is wound is installed at an end of the container, and the third feature that a plurality of cylindrical rollers having the same length and diameter are installed in the container in parallel and spaced apart positions the length of the width of the container, and the suspension prepared in the first step is filled into the new container. The arrangement of the plurality of cylindrical rollers in the new container is as follows: a first roller is installed at a position corresponding to a height at which the top of the first roller contacts the synthetic resin film drawn out from the roll of material and at a position 1 cm or more away from one side of the new container, and a second roller is installed at a position that is farther away from one side of the new container than the installation position of the first roller by the size of the first roller. and at a position 1 cm or more away from the bottom of the new container, the last roller is placed at a position 1 cm or more away from the other side of the new container and at a position where its top is at the same height as the top of the first roller, the second-to-last roller is placed at a position farther from the other side of the new container by the size of the last roller compared to the placement position of the last roller and at a position 1 cm or more away from the bottom of the new container as the second roller, and the remaining rollers are placed at positions 1 cm or more away from the bottom of the new container as the second roller, and are equally spaced between the second roller and the second-to-last roller at a distance of not more than twice the diameter of the cylindrical roller; A roll of synthetic resin film wound around the roll of synthetic resin film, which has a first characteristic of having the same width as the width of the interference film to be manufactured and a second characteristic of having a thickness that causes an interference phenomenon of reflecting only light rays of a specific wavelength, is set in a roll of synthetic resin film drawing device installed in the new container, and the synthetic resin film is continuously drawn out from the roll of synthetic resin film at the same speed as the rotation speed of the two work rolls of the multi-stage rolling mill used in the fourth step. Thereafter, the leading end of the drawn synthetic resin film comes into contact with the top of the first roller, and then comes into contact with the side of the first roller to draw out the synthetic resin film from the first roller. The leading edge of the synthetic resin film moves along the side of the second roller, which is approximately 1 / 4 of the way around, and then the direction of movement of the synthetic resin film changes downward, moves, is immersed in the suspension, and then comes into contact with the side of the second roller. Since the rotation direction of the second roller is opposite to the rotation direction of the first roller, the leading edge of the synthetic resin film that has come into contact with the side of the second roller also comes into contact with the side of the second roller and moves along the side of the second roller, which is approximately 1 / 4 of the way around, and then the direction of movement of the synthetic resin film changes to a direction parallel to the bottom of the new container, and the first roller and the second roller and the synthetic resin film comes into contact with the side surfaces of the rollers in turn except for the last roller. Since the rotation direction of the rollers is the same as the rotation direction of the second roller, the leading edge of the synthetic resin film that has come into contact with the side surfaces of the rollers in turn advances through the suspension without changing its direction of movement and comes into contact with the side surface of the second-to-last roller. Since the rotation direction of the second-to-last roller is the same as the rotation direction of the second roller, the leading edge of the synthetic resin film that has come into contact with the side surface of the second-to-last roller moves forward through the suspension without changing its direction of movement and comes into contact with the side surface of the second-to-last roller. and moves along the side surface of the penultimate roller near one-quarter of the way thereabout, then changes its moving direction upward and moves forward, and after being pulled up from the suspension, comes into contact with the side surface of the last roller; since the rotation direction of the last roller is opposite to that of the penultimate roller, the leading edge of the synthetic resin film that has come into contact with the side surface of the last roller comes into contact with the last roller and moves along the side surface of the last roller near one-quarter of the way thereabout, then changes its moving direction and moves toward the gap between two work rolls that constitute a multi-stage rolling mill used in the fourth step;a third step in which a series of processes for the synthetic resin film is carried out as a continuous process for the synthetic resin film from the point where the synthetic resin film drawn out from the roll contacts the side surface of the first roller to the point where the synthetic resin film contacts the side surface of the last roller and changes its moving direction toward the gap between the two work rolls that make up the multi-stage rolling mill; First, the first feature is that the two work rolls have the same width, which is wider than the width of the interference film to be produced; the second feature is that the two work rolls have the same diameter, which is smaller than 1 / 10 of the width of the interference film to be produced; the third feature is that the gap between the two work rolls is set to a gap having a thickness 10% thinner than the thickness of the synthetic resin film; the fourth feature is that the two work rolls rotate in opposite directions at the same rotation speed, with the time required for one rotation being longer than 10 seconds; and the two work rolls are heated to a temperature 10°C higher than the boiling point of the alcohol constituting the suspension. A multi-stage rolling mill having two work rolls is prepared, which also has a fifth feature that the temperature of the roll is raised. Next, the leading end of the synthetic resin film that has been treated in the third step is inserted into the gap between the two work rolls. As a result, the leading end of the synthetic resin film is drawn into the gap between the two work rolls, and the synthetic resin film is continuously subjected to a compressive stress according to the size of the gap between the two work rolls. At this time, first, the alcohol from the suspension that has been evenly attached to the entire surface of the synthetic resin film evaporates, and then the alcohol is evaporated from the entire surface of the synthetic resin film. Then, the graphene aggregates constituting the suspension are deposited with their flat surfaces overlapping each other, and the entire surface of the synthetic resin film is covered with the graphene aggregates with their flat surfaces overlapping each other. Next, compressive stress is applied to the graphene aggregates, and first, the surface layer of the graphene aggregates collapses. The surface layer of the graphene aggregates deposited at the edge of the synthetic resin film moves to the edge, and the flat surfaces overlap each other at the edge. The surface layer of the graphene aggregates deposited other than at the edge moves to the edge after the gap between the two work rolls. The graphene moves toward the surface of the graphene aggregate, and the compressive stress is applied to the graphene aggregate, and the gaps between the overlapping flat surfaces of the graphene gradually narrow. When the flat surfaces come into direct contact with each other, frictional heat is generated on the flat surfaces, and all of the overlapping flat surfaces are bonded together by the frictional heat, forming a graphene film consisting of the graphene aggregate, which has a thickness of 2 nm or less and a total light transmittance of 85% or more. Furthermore, the synthetic resin film elastically deforms, and the thickness of the synthetic resin film is reduced by 10%, and the entire surface of the elastically deformed synthetic resin film is covered witha fourth step of continuously discharging a film, in which the graphene film has been friction-welded and the graphene film has covered the entire surface of the synthetic resin film, from the gap between the two work rolls, and continuously winding up the discharged film by a winder that rotates at the same rotational speed as the two work rolls; The method for continuously carrying out all of these four steps is a method for continuously producing an interference film having a configuration in which the entire surface of a synthetic resin film having a thickness that causes an interference phenomenon in which only light having a specific wavelength is reflected is covered with a graphene film having a thickness of 2 nm or less and a total light transmittance of 85% or more.

2. The method for continuously manufacturing an interference film according to claim 1 is a method for continuously manufacturing a first interference film that emits light with relatively high saturation, the method for continuously manufacturing the first interference film comprising: The synthetic resin film described in claim 1 is a film made of acrylic resin, and the film thickness d of the film causing the interference phenomenon of reflecting only light rays having a specific wavelength described in claim 1 is such that, in the relational expression d=(m+1 / 2) / 2·λ / n, where λ is the wavelength of the light rays causing the interference phenomenon, n is the refractive index of the acrylic resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d of the film causing the interference phenomenon is 3.0 μm or more, and the difference between the film thicknesses d of the integer value m and the integer value (m−1) causing the interference phenomenon is a difference equal to or greater than the deviation in thickness of the acrylic resin film, and the difference between the film thicknesses d of the integer value m and the integer value (m+1) causing the interference phenomenon is such that the difference between the film thicknesses d of the acrylic resin film and the integer value (m+1) causing the interference phenomenon is a first integer value m at which the film thickness d of the film causing the interference phenomenon is 3.0 μm or more, and a method for continuously producing a first interference film that emits light having a relatively high saturation, the method comprising: using an integer value m between the first integer value and the second integer value as the integer value m in the relational expression, the wavelength of a light ray that causes an interference phenomenon as λ; using the refractive index of the acrylic resin film at the wavelength of the light ray that causes the interference phenomenon as n in the relational expression; determining a film thickness d of a film that causes an interference phenomenon that reflects only light having the wavelength specified by the relational expression; using the acrylic resin film having the film thickness d as the synthetic resin film of claim 1; and continuously carrying out all of the processing consisting of the four steps set forth in claim 1;

3. The method for continuously manufacturing an interference film according to claim 1 is a method for continuously manufacturing a second interference film that emits light with a relatively high saturation, the method for continuously manufacturing the second interference film comprising: The synthetic resin film described in claim 1 is a film made of polycarbonate resin, and the film thickness d of the film that causes an interference phenomenon of reflecting only light rays having a specific wavelength described in claim 1 is such that, in the relational expression d = (m + 1 / 2) / 2 λ / n, where λ is the wavelength of the light rays that cause the interference phenomenon, n is the refractive index of the polycarbonate resin film at the wavelength of the light rays, and m is an integer value, a first integer value m that makes the film thickness d that causes the interference phenomenon 3.0 μm or more, and a difference between both film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m-1) are a difference equal to or greater than the deviation in thickness of the polycarbonate resin film, and a difference between both film thicknesses d that cause the interference phenomenon formed by the integer value m and the integer value (m+1) are a difference equal to or greater than the deviation in thickness of the polycarbonate resin film, and a method for continuously producing a second interference film that emits light having a relatively high saturation, the method comprising: using an integer value m between the first integer value and the second integer value as the integer value m in the relational expression, wherein the integer value m is between the first integer value and the second integer value, and a second integer value m whose difference is less than the deviation in thickness of the polycarbonate resin film; using the wavelength of the light that causes the interference phenomenon as λ in the relational expression; using the refractive index of the polycarbonate resin film at the wavelength of the light that causes the interference phenomenon as n in the relational expression; determining a film thickness d of a film that causes the interference phenomenon and reflects only light having the wavelength specified by the relational expression; using the polycarbonate resin film having the film thickness d as the synthetic resin film of claim 1; and continuously carrying out all of the processing consisting of the four steps of claim 1.

4. The method for continuously manufacturing an interference film according to claim 1 is a method for continuously manufacturing a third interference film that emits light with relatively high saturation, and the method for continuously manufacturing the third interference film comprises: The synthetic resin film described in claim 1 is a film made of polystyrene resin, and the film thickness d of the film causing an interference phenomenon of reflecting only light rays having a specific wavelength described in claim 1 is such that, in the relational expression d = (m + 1 / 2) / 2 λ / n, where λ is the wavelength of the light rays causing the interference phenomenon, n is the refractive index of the polystyrene resin film at the wavelength of the light rays, and m is an integer value, a first integer value m at which the film thickness d causing the interference phenomenon is 3.0 μm or more, and a difference between both film thicknesses d formed by the integer value m and the integer value (m-1) causing the interference phenomenon is a difference equal to or greater than the deviation in thickness of the polystyrene resin film, and a difference between both film thicknesses d formed by the integer value m and the integer value (m+1) causing the interference phenomenon is such that a difference between both film thicknesses d formed by the integer value m and the integer value (m+1) causing the interference phenomenon is equal to or greater than the deviation in thickness of the polystyrene resin film, and a first integer value m between the first integer value and the second integer value, and a second integer value m that results in a difference less than the deviation in thickness of the film of the first integer value and the second integer value as the integer value m in the relational expression; a wavelength of a light ray that causes an interference phenomenon as λ in the relational expression; a refractive index of the polystyrene resin film at the wavelength of the light ray that causes the interference phenomenon as n in the relational expression; a film thickness d of a film that causes an interference phenomenon and reflects only light rays having the wavelength specified by the relational expression;

5. The method for continuously manufacturing an interference film according to claim 1 is a method for continuously manufacturing a fourth interference film that emits light with relatively high saturation, the method for continuously manufacturing the fourth interference film comprising: The synthetic resin film described in claim 1 is a film made of polyethylene terephthalate resin, and the film thickness d of the film causing an interference phenomenon of reflecting only light rays having a specific wavelength described in claim 1 is a film made of polyethylene terephthalate resin, and where λ is the wavelength of the light rays causing the interference phenomenon, n is the refractive index of the polyethylene terephthalate resin film at the wavelength of the light rays, and m is an integer value, the film thickness d is expressed as d=(m+1 / 2) / 2·λ / n, where m is an integer value and the first integer value m is such that the film thickness d causing the interference phenomenon is 3.0 μm or more, and the difference between the film thicknesses d of the integer value m and the integer value (m−1) causing the interference phenomenon is a difference equal to or greater than the deviation in thickness of the polyethylene terephthalate resin film, and the difference between the film thicknesses d of the integer value m and the integer value (m+1) causing the interference phenomenon is equal to or greater than the deviation in thickness of the polyethylene terephthalate resin film, a second integer m that is less than the deviation in thickness of the polyethylene terephthalate resin film, a wavelength of a light ray that causes an interference phenomenon being used as λ in the relational expression, a refractive index of the polyethylene terephthalate resin film at the wavelength of the light ray that causes the interference phenomenon being used as n in the relational expression, a film thickness d of a film that causes an interference phenomenon and reflects only light rays having the wavelength specified by the relational expression being determined, the polyethylene terephthalate resin film having the film thickness d being used as the synthetic resin film of claim 1, and a method of continuously performing all of the four steps of the process defined in claim 1 to produce a fourth interference film that emits light rays with relatively high saturation.

6. The method for continuously manufacturing an interference film according to claim 1 comprises the steps of: The alcohol having the three properties described in claim 1 is any one of ethanol, 1-propanol, and 2-propanol, and the method for continuously producing the interference film described in claim 1 is a method for continuously carrying out all of the treatments consisting of the four steps described in claim 1 using the alcohol having the three properties described in claim 1.

7. A method for continuously manufacturing an interference film by the method described in claim 1, cutting a part of the interference film into the shape of the surface of a substrate, and bonding the cut interference film to the surface of the substrate to form a new substrate in which the interference phenomenon caused by the interference film continues, comprises:

10. The method of claim 1, wherein an interference film is continuously manufactured, a portion of the interference film is cut into the shape of the surface of a substrate having a thickness at least 10 times that of the interference film, the cut interference film is superimposed on the surface of the substrate, a plate-shaped jig having the shape of the cut interference film is further superimposed on the surface of the cut interference film, and the entire plate-shaped jig is uniformly compressed by a compressor, whereby the surface of the interference film comes into contact with the convex portions of the uneven surface of the substrate, frictional heat is generated in the convex portions, and the frictional heat bonds the convex portions to the surface of the interference film, and the interference film is bonded to the surface of the substrate, and then the plate-shaped jig is separated from the interference film, whereby the substrate is formed as a new substrate in which the interference phenomenon caused by the interference film continues. A method for continuously manufacturing an interference film using the method described in claim 1, cutting a portion of the interference film to the shape of the surface of a substrate, and bonding the cut interference film to the surface of the substrate to form a new substrate in which the interference phenomenon caused by the interference film continues.

8. A method for continuously manufacturing a plurality of interference films that emit light beams of different hues according to the method of claim 1 and using the plurality of interference films to form a new interference film that emits a light beam that is a mixture of the plurality of light beams of different hues, comprises the steps of: According to the method of claim 1, a plurality of interference films that cause an interference phenomenon of reflecting light rays of different hues are continuously manufactured, portions of the plurality of interference films are cut into predetermined shapes, the cut interference films are brought close to each other and arranged on the entire surface of a base material having a thickness at least 10 times that of the interference films, a plate-shaped jig having the shape of the surfaces of the plurality of interference films arranged on the entire surface of the base material is superimposed on the surfaces of the plurality of interference films, and the entire plate-shaped jig is uniformly compressed by a compressor, thereby bringing the surfaces of the plurality of interference films into contact with convex portions of the uneven surface of the base material, generating frictional heat in the convex portions, which bonds the convex portions to the surfaces of the plurality of interference films and the plurality of interference films to the surface of the base material, and then the plate-shaped jig is separated from the plurality of interference films, thereby forming a new interference film on the surface of the base material that emits a light beam that is a mixture of light rays of different hues emitted by the plurality of interference films. A method for forming a new interference film that emits a light beam that is a mixture of the plurality of light beams having different hues using a plurality of interference films that emit light beams having different hues.

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