WO2010032783A1 - Optical interference coating - Google Patents

Optical interference coating Download PDF

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Publication number
WO2010032783A1
WO2010032783A1 PCT/JP2009/066249 JP2009066249W WO2010032783A1 WO 2010032783 A1 WO2010032783 A1 WO 2010032783A1 JP 2009066249 W JP2009066249 W JP 2009066249W WO 2010032783 A1 WO2010032783 A1 WO 2010032783A1
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Prior art keywords
thin film
layer
film
interference thin
refractive index
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PCT/JP2009/066249
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French (fr)
Japanese (ja)
Inventor
一光 田中
信政 南部
太郎 北村
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株式会社ライク
株式会社タナカ技研
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Publication of WO2010032783A1 publication Critical patent/WO2010032783A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters
    • G02B5/285—Interference filters comprising deposited thin solid films
    • G02B5/287—Interference filters comprising deposited thin solid films comprising at least one layer of organic material

Definitions

  • the present invention relates to an optical interference thin film in which a unique reflected light for decoration can be obtained by a multilayer thin film laminated on the surface of an article.
  • Patent Document 1 High refractive index so that the concavo-convex structure is preserved up to the uppermost layer on the structural color body (Patent Document 1) whose color changes according to the observation direction due to the reflection / interference phenomenon or the ground surface having a fine concavo-convex structure
  • Patent Document 2 A structural color body (Patent Document 2) is known in which two types of optical thin films having a low refractive index are laminated and an exterior color in a limited wavelength band including a specific color is clearly observed.
  • Multilayer optical thin films used in these structural color bodies are based on the design principle of conventional optical interference thin films, assuming that the thin film layers to be laminated are sufficiently transparent.
  • a unique appearance color is obtained by utilizing wavelength selectivity according to the combination of the refractive index and the film thickness, such as a film or a color separation filter.
  • the structural color body of Patent Document 1 has a feature that the color tone changes when the observation direction is changed, and the structural color body of Patent Document 2 has a characteristic that clear reflected light in a specific wavelength band can be obtained.
  • An object of the present invention is to provide an optical interference thin film that can give a deep and unique hue as seen in lacquer coating to the appearance colors of various products and that can be easily manufactured industrially. is there.
  • the present invention pays attention to the fact that the unique shade of lacquer coating cannot be realized by ignoring the light absorption of the thin film.
  • a decorative effect having a unique color is obtained by utilizing a synergistic effect of the light interference phenomenon and the light absorption phenomenon by the thin film having a multilayer structure. Therefore, the optical interference thin film of the present invention has a film configuration in which an interference thin film layer in which at least two types of thin films having different refractive indexes n are laminated is formed on the base substrate side, and the surface side is covered with a transparent protective film.
  • the protective layer is intended to protect the interference thin film layer from mechanical shocks applied from the outside and changes in the surrounding environment, and is transparent with a refractive index n of 1.35 to 1.65 and a film thickness of 0.3 to 100 ⁇ m.
  • a membrane can be utilized.
  • the base substrate itself is a material with excellent adhesion, the optical interference thin film may be laminated on the surface of the base substrate. However, if the structure of the substrate surface itself is not suitable for thin film lamination, the substrate surface In order to improve adhesion, the optical interference thin film may be laminated after forming a metal layer.
  • At least one kind of thin film used for the interference thin film layer is required to have a refractive index n and an extinction coefficient k having significant values.
  • a titanium nitride film can be effectively used. it can.
  • a titanium nitride film is used as one interference thin film layer, it is easy to use a nitride film as the other thin film.
  • a silicon nitride film can be used preferably.
  • an interference thin film layer can be formed by alternately laminating these titanium nitride films and silicon nitride films.
  • an interference thin film layer can be obtained by using a thin film other than a nitride film
  • a metal film can also be used as a transparent thin film having absorption by appropriately adjusting the film thickness, and thus different metal films can be sequentially used. It is also possible to obtain the desired interference thin film layer by laminating the film or a combination with a dielectric film.
  • the optical interference thin film of the present invention not only can the reflected light from the object surface be appropriately colored by the synergistic effect of the interference action and the light absorption action of the optical thin film, but also the depth can be increased by the light absorption action of the thin film. It is possible to give a soothing shade of color and to obtain a unique decorative effect with a high-class feeling like lacquering.
  • a protective layer and a stain prevention layer durability against the use environment and resistance to mechanical impact can be improved, and stains such as fingerprints can be made inconspicuous and a high-quality decoration effect can be maintained.
  • the optical interference thin film of the present invention is used as a decorative coating 2, from the metal layer L 1 and the second thin film layer L 2 to the eighth thin film layer L 8 formed on the surface of the base substrate 3.
  • the interference thin film layer Ls composed of seven layers, and a ninth protective layer L9 laminated on the surface thereof.
  • the base substrate 3 is an exterior part of various products or components, and the material thereof may be an appropriate material such as metal, plastic, ceramic.
  • the metal layer L1 is a layer for covering the surface of the base substrate 3 so that the surface color of the base substrate 3 itself is not mixed with the unique reflected light obtained by the decorative coating 2, and aluminum (Al), silver (Ag), A near-colorless reflective color such as chromium (Cr) or nickel (Ni) is suitable, but a metal such as copper (Cu) or gold (Au) can be used as necessary. Further, depending on the material of the base substrate 3, adhesion may be a problem with the thin film laminated thereon. In such a case, the adhesion is improved by interposing these metal layers L ⁇ b> 1. Can do. Therefore, the metal layer L1 is omitted when the surface of the base substrate 3 is excellent in adhesion to the thin film and the surface color is of a level that does not affect the reflected light to be obtained by the decorative coating 2. Is also possible.
  • the metal layer L1 to the eighth thin film layer L8 can be efficiently formed by ion plating, and the protective layer L9 can be easily formed by coating. Further, the metal layer L1 can be formed by plating or painting in addition to PVD such as ion plating or vacuum deposition.
  • the film configuration of the decorative coating 2 is as shown in Table 1.
  • the refractive index n at the center wavelength ⁇ 0 is 0.83413
  • the extinction coefficient k is 5.63192.
  • Aluminum has high adhesion to various materials generally used for the base substrate 3, and also has excellent adhesion to the interference thin film layer Ls laminated thereon, and not only ion plating but also vacuum deposition and sputtering. However, it can be formed easily.
  • the aluminum thin film is not only used for the purpose of improving the adhesion, but also formed as an interference thin film layer Ls as one constituent layer having a refractive index n of 0.83413 at the center wavelength ⁇ 0 and an extinction coefficient k of 5.63192. Can also be used.
  • the interference thin film layers Ls from the second layer to the eighth layer are alternating layers of a titanium nitride film (TiN) having a refractive index n of 2.44582 and a silicon nitride film (SiN) having a refractive index n of 1.70199. It is configured. Since the titanium nitride films of the thin film layers L2, L4, L6, and L8 have an extinction coefficient k of 0.28458 and act as a light absorption film, the light passing through these titanium nitride films has a physical thickness. Decreases accordingly.
  • the interference thin film layer Ls gives a wavelength-dependent intensity modulation to the reflected light by an optical interference action determined by a combination of the refractive index n of the titanium nitride film and the silicon nitride film and the optical film thickness nD / ⁇ 0. .
  • the ninth protective layer L9 is a transparent fluororesin coating material layer, and its physical film thickness is set to 10 ⁇ m within the range of 0.3 to 100 ⁇ m.
  • Such spectral reflection characteristics provide intensity modulation that causes the interference thin film layer Ls to bias the peak of reflected light toward the long wavelength side, and the light absorption action of the titanium nitride film and the aluminum metal layer L1 is in the visible light range.
  • the reflected light in the shorter wavelength region than the center wavelength ⁇ 0 becomes 7 to 8% at most, and is buried in the red reflected light so that it is hardly noticeable.
  • the red reflected light thus obtained is not observed as surface reflection from the protective layer L9, but reflected light from the interface between the titanium nitride film and the silicon nitride film is observed through these nitride film and protective film L9. For this reason, the color tone has a deep hue as seen in lacquering.
  • the operation of the interference thin film layer Ls described above is not necessarily unique to the alternating layers of the titanium nitride film and the silicon nitride film.
  • at least two types of thin films having different refractive indexes n are alternately laminated, and the optical thickness is adjusted to give the reflected light a wavelength-dependent intensity modulation. At least one of them may have a light absorbing action.
  • a film, a dielectric film, or the like can be used as appropriate.
  • the interference thin film layer Ls is composed of a combination of a titanium nitride film and a silicon nitride film as in the above embodiment, nitrogen gas can be commonly used in the film formation process, so that the film formation conditions can be stabilized. This is advantageous in maintaining the film, and after the metal layer L1 is formed, the two kinds of thin films may be alternately stacked, so that the film forming operation can be made efficient. Furthermore, since the nitride films are stacked, stress between layers is less likely to occur, which is advantageous in preventing peeling failure.
  • the protective layer L9 protects the interference thin film layer Ls from mechanical shocks, and prevents the interference thin film layer Ls from being deteriorated or altered by changes in the surrounding environment. Since it has a low refractive index, it also has an effect of reducing surface reflection. In addition, the protective layer L9 substantially reduces the incident angle of external light to the interference thin film layer Ls as compared with the case where it directly enters from the atmosphere, and reduces the angle dependency of the spectral reflection characteristics peculiar to the multilayer interference thin film. To do. This makes it possible to obtain a stable reflected color with little change in color tone even when the observation angle is slightly changed.
  • the spectral reflection characteristics when an antireflection film is laminated on the surface are as shown by the broken line, and the reflected light on the short wavelength side is reduced as a whole because the amount of reflected light is reduced. It turns out that it is further suppressed.
  • a transparent coating material of silicon or Teflon (registered trademark) is preferably used, and the thickness is preferably in the range of 10 to 50 ⁇ m. These coating materials have the effect of making fingerprints and other dirt inconspicuous, and also have excellent wiping properties. When fingerprints are attached, they can be easily wiped after moistening the surface with a small amount of water or solvent. .
  • the film calculation was performed according to the same method to prepare samples for blue reflection, green reflection, and magenta reflection, and the obtained spectral reflection characteristics are shown in FIGS.
  • the broken line represents the characteristics of the laminated layers up to the protective layer
  • the solid line represents the characteristics of a layer obtained by further laminating a transparent coating material of silicon or Teflon (registered trademark) as an antireflection film. From these results, it can be seen that by changing the film configuration, the reflected light of the lacquered tone that is darkly sunk for various color tones can be obtained.
  • the ion plating apparatus used for the test film formation has a structure schematically shown in FIG.
  • a dome-shaped substrate holder 11 is provided in the vacuum chamber 10 so as to be rotatable around a vertical axis as shown in the figure, and the sample 12 shown in FIG.
  • argon gas is introduced as a discharge gas into the vacuum layer 10 to generate a plasma P of argon gas on the lower surface of the substrate holder 11.
  • nitrogen gas is introduced into the vacuum chamber 10 as a reaction gas, titanium particles are evaporated from an evaporation source 15 using an electron gun as indicated by an arrow 16, and accelerated ions are directed from the plasma gun 17 toward the substrate holder 11. Supply.
  • accelerated ions By supplying accelerated ions, a dense titanium nitride film can be formed on each of the surfaces 12a to 12e of the sample 12.
  • the film forming conditions at this time are as follows: the heating temperature of the sample 12 is 300 ° C., and the introduction ratio of argon gas and nitrogen gas is argon gas 130 SCCM (Standard Cubic Centimeter per Minute: 0 ° C., flow rate cc / min at 1 atm. Nitrogen gas is 40 SCCM, the degree of vacuum is 1.23 ⁇ 10 ⁇ 2 Pa, and the deposition rate is 5 ⁇ / sec. A 10 kW plasma gun manufactured by JEOL Ltd. was used as the plasma gun.
  • the film thickness, spectral transmittance, and spectral reflectance of the single layer titanium nitride film obtained by the above test film formation are measured, and known data, for example, the surface reflectance and film thickness of the sample 12 before film formation are measured.
  • the spectral reflection characteristics of the titanium nitride film were analyzed for each wavelength, and the values of the refractive index n and the extinction coefficient k were obtained by calculation.
  • the calculated values of the refractive index n and the extinction coefficient k are as shown in FIG. 8, and it was confirmed that each has wavelength dependency.
  • the solid line is the result when the substrate temperature of sample 12 is set to 300 ° C.
  • the refractive index n of the titanium nitride film is in the range of “2.0 ⁇ n ⁇ 3.0” in the wavelength range of 350 nm to 800 nm, as can be seen from the measurement result of FIG.
  • the extinction coefficient k needs to be in the range of “0.5 ⁇ k ⁇ 1.5”.
  • the titanium nitride film is used as a thin film having a higher refractive index than the silicon nitride film.
  • the refractive index n is high.
  • the refractive index n is below the lower limit, it becomes difficult to obtain spectral reflectance characteristics with wavelength selectivity, and the number of thin films increases in order to obtain desired characteristics. This has the disadvantage of increasing manufacturing costs.
  • the extinction coefficient k has a value of about “2.0” at most in the visible light range, but the metal film has an extinction coefficient as seen in the aluminum thin films listed in Table 1. k reaches “5.61922” at the center wavelength ⁇ 0 .
  • n 0.83413
  • the characteristics are as shown in FIG. According to this spectral reflection characteristic, even though a metal film is used, the total amount of reflected light is about 35% at the short wavelength side, and a light cyan color is observed sunk darkly, and a unique hue can be obtained. Recognize. Also in the embodiment using such a metal film, the refractive index n of one thin film is in the range of “1.36 to 3.5”, and the extinction coefficient k is in the range of “0.1 to 6”. That is satisfied.
  • FIG. 10 schematically shows the process.
  • a peelable adhesive layer 21 is applied to a base film 20 that serves as a support for the optical interference thin film, and a hard coat layer 22 for protecting the optical interference thin film is formed thereunder.
  • a film For the base film 20, a sheet made of PET (polyethylene terephthalate) can be suitably used.
  • an optical interference thin film 24 is formed under the hard coat layer 22.
  • the laminated body obtained in the steps up to FIG. 10B is cut according to the housing size of the product, and the insert part 25 is obtained.
  • the front and back of the optical interference thin film 24 of the insert part 25 are reversed and inserted into the lower mold 26, and then the upper mold 27 is aligned.
  • the casing 28 is molded by injection into a cavity between the molds.
  • the insert part 25 is integrally formed with the housing 28.
  • the base film 20 is peeled off together with the adhesive layer 21 from the molded product taken out from the mold.
  • an optical interference thin film 24 covered with the protective hard coat layer 22 is finally formed on the surface of the housing 28.
  • the present invention has been described based on the illustrated embodiment.
  • the film configuration of the interference thin film layer Ls it is possible to obtain spectral reflection characteristics that darkly reflect various color lights.
  • the spectral reflection characteristics similar to those in FIG. 2 can be obtained even by film formation by the reactive sputtering method, and various methods other than ion plating can be used as the film formation method. it can.
  • plating can be used for forming a metal film, and an approximately equivalent refractive index n and extinction coefficient k can be obtained.

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  • General Physics & Mathematics (AREA)
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Abstract

A metal layer (L1) is formed on an underlying substrate (3), and an interference coating layer (Ls) laminating coating layers (L2-L8) having different refractive indexes (n) is provided thereon.  A transparent protective layer (L9) is formed on the surface of the interference coating layer (Ls).  The interference coating layer (Ls) imparts wavelength-dependent intensity modulation to reflected light, and the quantity of reflected light is kept low by light absorption of the coating layers (L2, L4, L8) thus providing an exterior color having an unique tone of color.  When the complex refractive index N of the coating layers (L2, L4, L8) is represented by “N=n-ik” using the refractive index n, an extinction coefficient k, and an imaginary number i, following relations are satisfied: “1.36≤n≤3.5” and “0.1≤k≤6”

Description

光学干渉薄膜Optical interference thin film
　本発明は、物品の表面に積層された多層薄膜により装飾用の独特の反射光が得られる光学干渉薄膜に関するものである。 The present invention relates to an optical interference thin film in which a unique reflected light for decoration can be obtained by a multilayer thin film laminated on the surface of an article.
　製品の外観色はデザイン面での影響力も大きいことから、製品外装への着色には様々な工夫がなされてきている。これまではメッキや塗装により外装表面への着色を行うのが一般であるが、排水処理や有機溶剤の処理など、環境保全のための対策が不可欠となっている。また、これらの手法で外装に着色を施した場合、いずれも顔料や染料自体の色がそのまま外観色として現れるものがほとんどで、漆塗りに見られるような深みのある高級感をもった色合いの外観色は得られていない。 Since the appearance color of the product has a great influence on the design, various ideas have been made for coloring the product exterior. Until now, it has been common to color the exterior surface by plating or painting, but measures for environmental conservation such as wastewater treatment and organic solvent treatment are indispensable. In addition, when the exterior is colored by these methods, most of the colors of the pigments and dyes themselves appear as they are as they are, and they have a deep and high-grade hue as seen in lacquering. Appearance color is not obtained.
　こうした背景から、微細な物理的構造によってひき起こされる光学的な干渉現象を利用して外観色に独特の色合いをもたせる試みがいくつかなされてきている。例えば、不要な反射光を除去するために光吸収性をもたせた下地面に高屈折率・低屈折率の二種類の光学薄膜を光の波長オーダーの光学膜厚で積層し、入射した光の反射・干渉現象により観察方向に応じて色が変化する構造性発色体（特許文献１）や、微細な凹凸構造をもつ下地面に、その凹凸構造が最上層まで保存されるように高屈折率・低屈折率の二種類の光学薄膜を積層し、特定色を含む限られた波長帯の外装色が鮮明に観察される構造性発色体（特許文献２）が知られている。 Against this background, some attempts have been made to give the appearance color a unique hue by utilizing the optical interference phenomenon caused by the fine physical structure. For example, two types of optical thin films with a high refractive index and a low refractive index are laminated with an optical film thickness in the order of the wavelength of light on the base surface provided with light absorptivity to remove unnecessary reflected light. High refractive index so that the concavo-convex structure is preserved up to the uppermost layer on the structural color body (Patent Document 1) whose color changes according to the observation direction due to the reflection / interference phenomenon or the ground surface having a fine concavo-convex structure A structural color body (Patent Document 2) is known in which two types of optical thin films having a low refractive index are laminated and an exterior color in a limited wavelength band including a specific color is clearly observed.
特開平７－３３１５３２号公報JP-A-7-331532 特開２００５－１５３１９２号公報JP 2005-153192 A
　これらの構造性発色体に用いられる多層光学薄膜は、積層する薄膜層が充分に透明であることを前提とし、基本的には従来の光学干渉薄膜の設計原理を基本にしており、例えば反射防止膜や色分解フィルタなどのように屈折率と膜厚との組み合わせに応じた波長選択性を利用して独特の外観色を得ている。しかしながら、特許文献１の構造性発色体では観察方向を変えたときに色調が変化するという特徴、また特許文献２の構造性発色体では特定波長帯域の鮮明な反射光が得られるという特徴はあるものの、漆塗りを多層に重ねた漆器が呈するような深みのある独特の色合いをもった外観色を得ることはできない。 Multilayer optical thin films used in these structural color bodies are based on the design principle of conventional optical interference thin films, assuming that the thin film layers to be laminated are sufficiently transparent. A unique appearance color is obtained by utilizing wavelength selectivity according to the combination of the refractive index and the film thickness, such as a film or a color separation filter. However, the structural color body of Patent Document 1 has a feature that the color tone changes when the observation direction is changed, and the structural color body of Patent Document 2 has a characteristic that clear reflected light in a specific wavelength band can be obtained. However, it is not possible to obtain an appearance color that has a deep and unique hue that lacquerware with multiple layers of lacquer coating exhibits.
　また、最近では携帯してパーソナルユースで利用される双眼鏡や小型のオーディオ機器，モバイルコンピュータ，携帯電話機などでは、その外観デザインに個性化や高級感が求められている。したがって各種製品の外観色として、漆塗りが呈するような深みのある独特の色合いのものを工業的に再現できるようにすることは、製品デザインのバリエーションを広げる意味で大きなメリットがある。 In recent years, binoculars, small audio devices, mobile computers, mobile phones, etc. that are carried for personal use are required to have a distinctive and high-class appearance. Therefore, it is a great advantage in terms of widening variations in product design to make it possible to industrially reproduce the appearance colors of various products that have a deep and unique color that lacquering exhibits.
　本発明の目的は、各種製品の外観色に漆塗りに見られるような深みのある独特の色合いをもたせることができ、しかも工業的に簡便に製造することができる光学干渉薄膜を提供することにある。 An object of the present invention is to provide an optical interference thin film that can give a deep and unique hue as seen in lacquer coating to the appearance colors of various products and that can be easily manufactured industrially. is there.
　本発明は上記目的を達成するにあたり、漆塗りが呈する独特の色合いは薄膜の光吸収を無視しては実現できないことに着目し、光学干渉薄膜を用いながらも光学薄膜に適度の光吸収能をもたせ、多層構成の薄膜による光干渉現象と光吸収現象との相乗効果を利用して独特の色合いをもつ装飾効果を得るようにしている。このため本発明の光学干渉薄膜は、下地基板側に屈折率ｎが異なる少なくとも２種類の薄膜を積層した干渉薄膜層を形成するとともにその表面側を透明な保護膜で覆った膜構成を有し、前記干渉薄膜層を構成するいずれかの薄膜について、その複素屈折率Ｎを屈折率ｎ、消衰係数ｋ、虚数ｉを用いて「Ｎ＝ｎ－ｉｋ」としたとき、「１．３６≦ｎ≦３．５」かつ「０．１≦ｋ≦６」が満たされることを特徴としている。 In order to achieve the above object, the present invention pays attention to the fact that the unique shade of lacquer coating cannot be realized by ignoring the light absorption of the thin film. In addition, a decorative effect having a unique color is obtained by utilizing a synergistic effect of the light interference phenomenon and the light absorption phenomenon by the thin film having a multilayer structure. Therefore, the optical interference thin film of the present invention has a film configuration in which an interference thin film layer in which at least two types of thin films having different refractive indexes n are laminated is formed on the base substrate side, and the surface side is covered with a transparent protective film. When any of the thin films constituting the interference thin film layer has a complex refractive index N of “N = n−ik” using a refractive index n, an extinction coefficient k, and an imaginary number i, “1.36 ≦ n ≦ 3.5 ”and“ 0.1 ≦ k ≦ 6 ”are satisfied.
　保護層は外部から加わる機械的な衝撃や周囲環境の変化から干渉薄膜層を保護するためのもので、屈折率ｎが１．３５～１．６５、膜厚が０．３～１００μｍの透明な膜を利用することができる。さらに、その上に膜厚が３～５０μｍの範囲となるようにテフロン（登録商標）系またはシリコン系の透明な塗装材料層を設け、これにより指紋などの汚れを防ぐようにすることが望ましい。下地基板自体が密着性に優れた材料である場合には、下地基板の表面に上記光学干渉薄膜を積層すればよいが、基板表面自体の構造が薄膜の積層に適していない場合には基板表面に密着性を高めるために金属層を形成してから前記光学干渉薄膜を積層すればよい。 The protective layer is intended to protect the interference thin film layer from mechanical shocks applied from the outside and changes in the surrounding environment, and is transparent with a refractive index n of 1.35 to 1.65 and a film thickness of 0.3 to 100 μm. A membrane can be utilized. Further, it is desirable to provide a Teflon (registered trademark) -based or silicon-based transparent coating material layer so that the film thickness is in the range of 3 to 50 μm, thereby preventing smudges such as fingerprints. If the base substrate itself is a material with excellent adhesion, the optical interference thin film may be laminated on the surface of the base substrate. However, if the structure of the substrate surface itself is not suitable for thin film lamination, the substrate surface In order to improve adhesion, the optical interference thin film may be laminated after forming a metal layer.
　干渉薄膜層に用いられる少なくとも一種類の薄膜には屈折率ｎと消衰係数ｋが有意の値をもつことが要求されるが、このような薄膜としては窒化チタン膜を効果的に用いることができる。また、窒化チタン膜を干渉薄膜層にひとつに用いる場合には他のひとつの薄膜にも窒化膜を用いるのが簡便で、この場合、窒化シリコン膜を好適に用いることができる。さらに、これらの窒化チタン膜と窒化シリコン膜とを交互に積層して干渉薄膜層を構成することも可能となる。窒化膜以外の薄膜を用いて干渉薄膜層を得ることもできるが、金属膜もその膜厚を適切に調節することによって吸収をもつ透明な薄膜として用いることができ、したがって異種の金属膜を順次に積層し、あるいは誘電体膜との組み合わせにより所期の干渉薄膜層を得ることも可能となる。 At least one kind of thin film used for the interference thin film layer is required to have a refractive index n and an extinction coefficient k having significant values. For such a thin film, a titanium nitride film can be effectively used. it can. When a titanium nitride film is used as one interference thin film layer, it is easy to use a nitride film as the other thin film. In this case, a silicon nitride film can be used preferably. Further, an interference thin film layer can be formed by alternately laminating these titanium nitride films and silicon nitride films. Although an interference thin film layer can be obtained by using a thin film other than a nitride film, a metal film can also be used as a transparent thin film having absorption by appropriately adjusting the film thickness, and thus different metal films can be sequentially used. It is also possible to obtain the desired interference thin film layer by laminating the film or a combination with a dielectric film.
　本発明の光学干渉薄膜によれば、光学薄膜の干渉作用と光吸収作用との相乗効果により、物体表面からの反射光に適宜の着色を施すことができるだけでなく、薄膜の光吸収作用によって深みのある落ち着いた感じの色合いをもたせることができ、漆塗りのような高級感のある独特の装飾効果を得ることが可能となる。また、保護層や汚れ防止層を設けることにより、使用環境に対する耐久性や機械的な衝撃に対する耐性を高め、また指紋などの汚れを目立たなくして高品位の装飾効果を保つことができる。 According to the optical interference thin film of the present invention, not only can the reflected light from the object surface be appropriately colored by the synergistic effect of the interference action and the light absorption action of the optical thin film, but also the depth can be increased by the light absorption action of the thin film. It is possible to give a soothing shade of color and to obtain a unique decorative effect with a high-class feeling like lacquering. In addition, by providing a protective layer and a stain prevention layer, durability against the use environment and resistance to mechanical impact can be improved, and stains such as fingerprints can be made inconspicuous and a high-quality decoration effect can be maintained.
本発明を用いた装飾コーティングの概念図である。It is a conceptual diagram of the decorative coating using this invention. 装飾コーティングの分光反射特性の一例を示すグラフである。It is a graph which shows an example of the spectral reflection characteristic of a decorative coating. 青色系装飾コーティングの分光反射特性の一例を示すグラフである。It is a graph which shows an example of the spectral reflection characteristic of a blue type decorative coating. 緑色系装飾コーティングの分光反射特性の一例を示すグラフである。It is a graph which shows an example of the spectral reflection characteristic of a green type decorative coating. マゼンタ色系装飾コーティングの分光反射特性の一例を示すグラフである。It is a graph which shows an example of the spectral reflection characteristic of a magenta color system decorative coating. 成膜装置の模式図である。It is a schematic diagram of the film-forming apparatus. 試験成膜に用いたサンプルの外観図である。It is an external view of the sample used for test film-forming. 窒化チタン膜の屈折率及び消衰係数の波長依存性を示すグラフである。It is a graph which shows the wavelength dependence of the refractive index and extinction coefficient of a titanium nitride film. 金属膜による多層光学干渉薄膜の分光反射特性の一例を示すグラフである。It is a graph which shows an example of the spectral reflection characteristic of the multilayer optical interference thin film by a metal film. （Ａ）～（Ｄ）は、インサート成形手法の概略を示す説明図である。(A)-(D) are explanatory drawings showing an outline of an insert molding technique.
　図１に示すように、本発明の光学干渉薄膜は装飾コーティング２として用いられ、下地基板３の表面に形成された金属層Ｌ１、２層目の薄膜層Ｌ２から８層目の薄膜層Ｌ８までの７層で構成された干渉薄膜層Ｌｓ、さらにその表面に積層された９層目の保護層Ｌ９からなる。下地基板３は各種の製品あるいは部品の外装部分で、その材質は金属、プラスチック、セラミックなど適宜のものでよい。 As shown in FIG. 1, the optical interference thin film of the present invention is used as a decorative coating 2, from the metal layer L 1 and the second thin film layer L 2 to the eighth thin film layer L 8 formed on the surface of the base substrate 3. The interference thin film layer Ls composed of seven layers, and a ninth protective layer L9 laminated on the surface thereof. The base substrate 3 is an exterior part of various products or components, and the material thereof may be an appropriate material such as metal, plastic, ceramic.
　金属層Ｌ１は、装飾コーティング２で得られる独特の反射光に下地基板３自体の表面色が混じらないように下地基板３の表面を覆うための層で、アルミニウム（Ａｌ）や銀（Ａｇ）、クロム（Ｃｒ），ニッケル（Ｎｉ）などの無色に近い反射色のものが適するが、必要に応じて銅（Ｃｕ）や金（Ａｕ）などの金属を用いることも可能である。また、下地基板３の材質によっては、その上に積層される薄膜に対して密着性が問題になる場合があるが、こうした場合にはこれらの金属層Ｌ１を介在させることによって密着性を高めることができる。したがって、下地基板３の表面が薄膜との密着性に優れ、しかもその表面色も装飾コーティング２で得ようとする反射光に影響を与えない程度のものであるときには、金属層Ｌ１を省略することも可能である。 The metal layer L1 is a layer for covering the surface of the base substrate 3 so that the surface color of the base substrate 3 itself is not mixed with the unique reflected light obtained by the decorative coating 2, and aluminum (Al), silver (Ag), A near-colorless reflective color such as chromium (Cr) or nickel (Ni) is suitable, but a metal such as copper (Cu) or gold (Au) can be used as necessary. Further, depending on the material of the base substrate 3, adhesion may be a problem with the thin film laminated thereon. In such a case, the adhesion is improved by interposing these metal layers L <b> 1. Can do. Therefore, the metal layer L1 is omitted when the surface of the base substrate 3 is excellent in adhesion to the thin film and the surface color is of a level that does not affect the reflected light to be obtained by the decorative coating 2. Is also possible.
　金属層Ｌ１から８層目の薄膜層Ｌ８まではイオンプレーティングにより効率的に成膜することができ、また保護層Ｌ９は塗装により簡便に形成することができる。さらに、金属層Ｌ１については、イオンプレーティングや真空蒸着などのＰＶＤのほか、メッキ処理や塗装により形成することも可能である。上記装飾コーティング２の膜構成は表１のとおりである。 The metal layer L1 to the eighth thin film layer L8 can be efficiently formed by ion plating, and the protective layer L9 can be easily formed by coating. Further, the metal layer L1 can be formed by plating or painting in addition to PVD such as ion plating or vacuum deposition. The film configuration of the decorative coating 2 is as shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１には、各薄膜層の薄膜材料と、可視光域の略中心に相当する中心波長λ０（＝５６０ｎｍ）における各薄膜層の屈折率ｎ及び消衰係数ｋ、物理的膜厚Ｄ、中心波長λ０に対する相対的な光学的膜厚ｎＤ／λ０を示してある。表１において、下地基板３の表面に接する１層目の金属層Ｌ１はアルミニウムの薄膜で、その複素屈折率Ｎを屈折率ｎ、消衰係数ｋ、虚数ｉを用いて「Ｎ＝ｎ－ｉｋ」で表すとき、中心波長λ０における屈折率ｎは０．８３４１３、消衰係数ｋは５．６３１９２である。アルミニウムは下地基板３に一般に用いられる様々な素材との密着性が高く、またその上に積層される干渉薄膜層Ｌｓとの密着性にも優れ、しかもイオンプレーティングだけでなく真空蒸着やスパッタリングなどでも容易に成膜することができる。なお、アルニウムの薄膜は密着性を高める目的で用いられるだけでなく、中心波長λ０における屈折率ｎが０．８３４１３、消衰係数ｋが５．６３１９２である一構成層として干渉薄膜層Ｌｓにも利用することができる。 Table 1 shows a thin film material of each thin film layer, a refractive index n and an extinction coefficient k of each thin film layer at a central wavelength λ 0 (= 560 nm) corresponding to the approximate center of the visible light region, a physical film thickness D, The relative optical film thickness nD / λ 0 with respect to the center wavelength λ 0 is shown. In Table 1, the first metal layer L1 in contact with the surface of the base substrate 3 is an aluminum thin film, and its complex refractive index N is expressed as “N = n−ik” using a refractive index n, an extinction coefficient k, and an imaginary number i. ”, The refractive index n at the center wavelength λ 0 is 0.83413, and the extinction coefficient k is 5.63192. Aluminum has high adhesion to various materials generally used for the base substrate 3, and also has excellent adhesion to the interference thin film layer Ls laminated thereon, and not only ion plating but also vacuum deposition and sputtering. However, it can be formed easily. The aluminum thin film is not only used for the purpose of improving the adhesion, but also formed as an interference thin film layer Ls as one constituent layer having a refractive index n of 0.83413 at the center wavelength λ 0 and an extinction coefficient k of 5.63192. Can also be used.
　２層目から８層目までの干渉薄膜層Ｌｓは、屈折率ｎが２．４５８８２の窒化チタン膜（ＴｉＮ）と、屈折率ｎが１．７０１９９の窒化シリコン膜（ＳｉＮ）との交互層で構成されている。薄膜層Ｌ２，Ｌ４，Ｌ６，Ｌ８の窒化チタン膜は、その消衰係数ｋが０．２８４５８で光吸収膜として作用するから、これらの窒化チタン膜を通過する光はそれぞれの物理的膜厚に応じて減衰する。さらに、この干渉薄膜層Ｌｓは、窒化チタン膜及び窒化シリコン膜の屈折率ｎと光学的膜厚ｎＤ／λ０との組み合わせで決まる光干渉作用によって反射光に波長依存性のある強度変調を与える。なお、９層目の保護層Ｌ９は透明なフッソ樹脂の塗料材料層で、その物理的膜厚は０．３～１００μｍの範囲内である１０μｍにしてある。 The interference thin film layers Ls from the second layer to the eighth layer are alternating layers of a titanium nitride film (TiN) having a refractive index n of 2.44582 and a silicon nitride film (SiN) having a refractive index n of 1.70199. It is configured. Since the titanium nitride films of the thin film layers L2, L4, L6, and L8 have an extinction coefficient k of 0.28458 and act as a light absorption film, the light passing through these titanium nitride films has a physical thickness. Decreases accordingly. Further, the interference thin film layer Ls gives a wavelength-dependent intensity modulation to the reflected light by an optical interference action determined by a combination of the refractive index n of the titanium nitride film and the silicon nitride film and the optical film thickness nD / λ 0. . The ninth protective layer L9 is a transparent fluororesin coating material layer, and its physical film thickness is set to 10 μm within the range of 0.3 to 100 μm.
　表１の膜構成による装飾コーティング２の分光反射特性を図２に破線で示す。この特性からわかるように、短波長側で幾分のリップルはみられるものの、装飾コーティング２は中心波長λ０（＝５６０ｎｍ）よりも短波長の光をほとんど反射せず、また長波長側でも８００ｎｍで１０％程度の反射を示すだけで、暗く沈んだ赤色系の反射光色となる。なお、このような装飾コーティング２が可視光域で示す反射率のピークは必ずしも３５％以下に限られず、５０％以下であれば暗く沈んだ漆塗り調の反射光が得られる。 The spectral reflection characteristics of the decorative coating 2 having the film configuration shown in Table 1 are shown by broken lines in FIG. As can be seen from this characteristic, although some ripples are observed on the short wavelength side, the decorative coating 2 hardly reflects light having a shorter wavelength than the center wavelength λ 0 (= 560 nm), and 800 nm on the long wavelength side. Only a reflection of about 10% will result in a dark-sunk reddish reflected light color. In addition, the peak of the reflectance which such a decorative coating 2 shows in a visible light range is not necessarily limited to 35% or less, and if it is 50% or less, the reflected light of the lacquered tone which was darkly sunk is obtained.
　このような分光反射特性は、干渉薄膜層Ｌｓが反射光のピークを長波長側に偏らせるような強度変調を与え、また窒化チタン膜とアルミニウム金属層Ｌ１がもつ光吸収作用が可視光域の入射光及び反射光を減衰させることによる。これにより、中心波長λ０よりも短波長域の反射光は高々７～８％となり、赤色反射光に埋もれてほとんど目立たないようになる。しかもこうして得られる赤色の反射光は保護層Ｌ９からの表面反射として観察されるのではなく、窒化チタン膜と窒化シリコン膜との界面からの反射光がこれらの窒化膜及び保護膜Ｌ９を通して観察されるため、漆塗りに見られるような深い色合いをもった色調となる。 Such spectral reflection characteristics provide intensity modulation that causes the interference thin film layer Ls to bias the peak of reflected light toward the long wavelength side, and the light absorption action of the titanium nitride film and the aluminum metal layer L1 is in the visible light range. By attenuating incident and reflected light. As a result, the reflected light in the shorter wavelength region than the center wavelength λ 0 becomes 7 to 8% at most, and is buried in the red reflected light so that it is hardly noticeable. Moreover, the red reflected light thus obtained is not observed as surface reflection from the protective layer L9, but reflected light from the interface between the titanium nitride film and the silicon nitride film is observed through these nitride film and protective film L9. For this reason, the color tone has a deep hue as seen in lacquering.
　上述した干渉薄膜層Ｌｓの作用は、必ずしも窒化チタン膜と窒化シリコン膜との交互層特有のものではない。原理的には、屈折率ｎが異なる少なくとも２種類の薄膜を交互に積層し、それぞれの光学的膜厚を調節することによって反射光に波長依存性のある強度変調をもたせ、また２種類の薄膜の少なくとも一方に光吸収作用をもたせればよい。また、互いに屈折率ｎが異なる３種類以上の薄膜を組み合わせ、そのうちの少なくとも一種類に光吸収性のものを用いて干渉薄膜層Ｌｓを得ることも可能で、薄膜材料としても金属膜、金属酸化膜、誘電体膜などを適宜に使用することができる。 The operation of the interference thin film layer Ls described above is not necessarily unique to the alternating layers of the titanium nitride film and the silicon nitride film. In principle, at least two types of thin films having different refractive indexes n are alternately laminated, and the optical thickness is adjusted to give the reflected light a wavelength-dependent intensity modulation. At least one of them may have a light absorbing action. In addition, it is possible to obtain an interference thin film layer Ls by combining three or more types of thin films having different refractive indexes n and using at least one of them as a light absorbing material. A film, a dielectric film, or the like can be used as appropriate.
　ただし、上記実施形態のように干渉薄膜層Ｌｓを窒化チタン膜と窒化シリコン膜との組み合わせで構成しておくと、成膜過程で窒素ガスを共通に用いることができるので成膜条件を安定に保つ上で有利であり、しかも金属層Ｌ１を成膜した後には２種類の薄膜を交互に積層すればよいので成膜作業を効率化することができる。さらに、窒化膜同士の積層であるため層間のストレスも生じにくく剥離故障を防ぐうえでも有利である。 However, if the interference thin film layer Ls is composed of a combination of a titanium nitride film and a silicon nitride film as in the above embodiment, nitrogen gas can be commonly used in the film formation process, so that the film formation conditions can be stabilized. This is advantageous in maintaining the film, and after the metal layer L1 is formed, the two kinds of thin films may be alternately stacked, so that the film forming operation can be made efficient. Furthermore, since the nitride films are stacked, stress between layers is less likely to occur, which is advantageous in preventing peeling failure.
　なお、保護層Ｌ９は干渉薄膜層Ｌｓを機械的な衝撃から保護し、また周囲環境の変化によって干渉薄膜層Ｌｓが劣化・変質することを防ぐ作用をもつとともに、その下層の窒化チタン膜よりも低い屈折率であることから表面反射を低減させる効果も有する。また、この保護層Ｌ９は大気から直接的に入射する場合と較べて干渉薄膜層Ｌｓに対する外光の入射角を実質的に小さくし、多層の干渉薄膜特有の分光反射特性の角度依存性を軽減する。これにより、観察の角度を多少変えても色調変化が少ない安定した反射色を得ることが可能となる。 The protective layer L9 protects the interference thin film layer Ls from mechanical shocks, and prevents the interference thin film layer Ls from being deteriorated or altered by changes in the surrounding environment. Since it has a low refractive index, it also has an effect of reducing surface reflection. In addition, the protective layer L9 substantially reduces the incident angle of external light to the interference thin film layer Ls as compared with the case where it directly enters from the atmosphere, and reduces the angle dependency of the spectral reflection characteristics peculiar to the multilayer interference thin film. To do. This makes it possible to obtain a stable reflected color with little change in color tone even when the observation angle is slightly changed.
　さらに、保護層Ｌ９の表面反射を抑えるために、その表面に反射防止膜を積層したときの分光反射特性は破線で示すとおりで、全体的に反射光量が低下して短波長側の反射光がさらに抑えられていることがわかる。この反射防止膜にはシリコン系またはテフロン（登録商標）系の透明な塗装材料が好適に用いられ、その厚みは１０～５０μｍの範囲が好ましい。これらの塗装材料は指紋その他の汚れを目立たなくする作用をもち、また拭き取り性にも優れており、指紋などが付着したときには表面を少量の水や溶剤で湿らせた後に簡単に拭き取ることができる。 Furthermore, in order to suppress the surface reflection of the protective layer L9, the spectral reflection characteristics when an antireflection film is laminated on the surface are as shown by the broken line, and the reflected light on the short wavelength side is reduced as a whole because the amount of reflected light is reduced. It turns out that it is further suppressed. For this antireflection film, a transparent coating material of silicon or Teflon (registered trademark) is preferably used, and the thickness is preferably in the range of 10 to 50 μm. These coating materials have the effect of making fingerprints and other dirt inconspicuous, and also have excellent wiping properties. When fingerprints are attached, they can be easily wiped after moistening the surface with a small amount of water or solvent. .
　同様の手法にしたがってそれぞれ膜計算を行い、青色反射用、緑色反射用、マゼンタ色反射用のサンプルを作製し、得られた各々の分光反射特性を図３～図５に示す。それぞれ、破線が保護層まで積層したものの特性を表し、実線がさらにその上層にシリコン系またはテフロン（登録商標）系の透明な塗装材料を反射防止膜として積層させたものの特性を表している。これらの結果から、膜構成を変えることにより、様々な色調について暗く沈んだ漆塗り調の反射光を得られることがわかる。 The film calculation was performed according to the same method to prepare samples for blue reflection, green reflection, and magenta reflection, and the obtained spectral reflection characteristics are shown in FIGS. In each case, the broken line represents the characteristics of the laminated layers up to the protective layer, and the solid line represents the characteristics of a layer obtained by further laminating a transparent coating material of silicon or Teflon (registered trademark) as an antireflection film. From these results, it can be seen that by changing the film configuration, the reflected light of the lacquered tone that is darkly sunk for various color tones can be obtained.
　上述のように、装飾コーティング２によって得られる漆塗り調の独特の反射光は干渉薄膜層Ｌｓの作用によるもので、このような干渉薄膜層Ｌｓの設計は実質的に透明な光学薄膜（ｋ≒０）だけを対象とした従来の薄膜設計技術では対応が困難である。このため干渉薄膜層Ｌｓの膜設計に先立ち、特に光吸収をもたせる窒化チタン膜についてはその複素屈折率Ｎを「Ｎ＝ｎ－ｉｋ」とし、単層の窒化チタン膜を様々な成膜条件のもとで試験成膜した後に、そのサンプルの膜厚、分光透過率及び分光反射率などを解析して屈折率ｎと消衰係数ｋの値を求めた。 As described above, the unique reflected light in the lacquered tone obtained by the decorative coating 2 is due to the action of the interference thin film layer Ls, and the design of the interference thin film layer Ls is a substantially transparent optical thin film (k≈ It is difficult to cope with the conventional thin film design technology targeting only 0). Therefore, prior to the design of the interference thin film layer Ls, the complex refractive index N is set to “N = n−ik” particularly for a titanium nitride film having light absorption, and a single-layer titanium nitride film is subjected to various film formation conditions. After the original test film formation, the film thickness, spectral transmittance, spectral reflectance, and the like of the sample were analyzed to determine the values of refractive index n and extinction coefficient k.
　上記試験成膜に用いたイオンプレーティング装置は模式的に図６に示す構造をもつ。図６において、真空槽１０内にドーム状の基板ホルダ１１が垂直な軸を中心にして図示のように回転自在に設けられ、基板ホルダ１１に図４に示すサンプル１２を保持させた。サンプル１２は、正方形のステンレスプレート（ＳＵＳ３０４）の４辺をθ＝８０°に折り曲げたもので、各辺の折り曲げ高さｈが１６ｍｍ、折り曲げ後の各辺の長さＬは１００ｍｍである。そして、このサンプル１２を下に凸となるように基板ホルダ１１に固定し、各折り曲げ片の外側表面１２ａ～１２ｄと、これらの折り曲げ片１２ａ～１２ｄで囲まれた正方形の基板表面１２ｅのそれぞれに、単層の窒化チタン膜を中心波長λ０（＝５６０ｎｍ）で緑色の反射光が得られる所定膜厚で成膜した。 The ion plating apparatus used for the test film formation has a structure schematically shown in FIG. In FIG. 6, a dome-shaped substrate holder 11 is provided in the vacuum chamber 10 so as to be rotatable around a vertical axis as shown in the figure, and the sample 12 shown in FIG. The sample 12 is obtained by bending four sides of a square stainless steel plate (SUS304) at θ = 80 °, the bending height h of each side is 16 mm, and the length L of each side after bending is 100 mm. Then, the sample 12 is fixed to the substrate holder 11 so as to protrude downward, and the outer surfaces 12a to 12d of the bent pieces and the square substrate surface 12e surrounded by the bent pieces 12a to 12d, respectively. A single-layer titanium nitride film was formed with a predetermined film thickness at which green reflected light was obtained with a center wavelength λ 0 (= 560 nm).
　成膜に先立ち、真空層１０内に放電ガスとしてアルゴンガスを導入し、基板ホルダ１１の下面にアルゴンガスのプラズマＰを生成させる。蒸発時には反応ガスとして真空槽１０内に窒素ガスを導入し、電子銃を用いた蒸発源１５からチタン粒子を矢印１６で示すように蒸発させ、プラズマ銃１７からは基板ホルダ１１に向けて加速イオンを供給する。加速イオンの供給により、サンプル１２の各表面１２ａ～１２ｅに緻密な窒化チタン膜を形成することができる。 Prior to film formation, argon gas is introduced as a discharge gas into the vacuum layer 10 to generate a plasma P of argon gas on the lower surface of the substrate holder 11. At the time of evaporation, nitrogen gas is introduced into the vacuum chamber 10 as a reaction gas, titanium particles are evaporated from an evaporation source 15 using an electron gun as indicated by an arrow 16, and accelerated ions are directed from the plasma gun 17 toward the substrate holder 11. Supply. By supplying accelerated ions, a dense titanium nitride film can be formed on each of the surfaces 12a to 12e of the sample 12.
　この際の成膜条件は、サンプル１２の加熱温度が３００°Ｃ、アルゴンガスと窒素ガスとの導入比率は、アルゴンガス１３０ＳＣＣＭ（Standard  Cubic  Centimeter  per  Minute：０°Ｃ　１気圧における流量ｃｃ／ｍｉｎを表す単位に相当）に対して窒素ガス４０ＳＣＣＭ、真空度が１．２３×１０－２Ｐａ、成膜速度は５オングストローム／ｓｅｃである。また、プラズマ銃には日本電子工業（株）製の１０ｋＷプラズマ銃を用いた。 The film forming conditions at this time are as follows: the heating temperature of the sample 12 is 300 ° C., and the introduction ratio of argon gas and nitrogen gas is argon gas 130 SCCM (Standard Cubic Centimeter per Minute: 0 ° C., flow rate cc / min at 1 atm. Nitrogen gas is 40 SCCM, the degree of vacuum is 1.23 × 10 −2 Pa, and the deposition rate is 5 Å / sec. A 10 kW plasma gun manufactured by JEOL Ltd. was used as the plasma gun.
　この成膜条件のもとでサンプル１２の各表面１２ａ～１２ｅに緑色の反射光を呈する窒化チタンの薄膜が得られた。表面１２ｅの薄膜層による分光反射特性と、他の表面１２ａ～１２ｄの薄膜層による分光反射特性とを比較すると、反射光量が最大となるピーク波長の差異は１０ｎｍに留まり、また反射光量の差異は５％であった。この結果から、成膜を行う下地基板に多少の凹凸があったとしても分光反射特性が局所的に極端に変化することはなく、下地基板の形状にはある程度の自由度があることを確認することができた。 Under this film forming condition, a titanium nitride thin film exhibiting green reflected light on each of the surfaces 12a to 12e of the sample 12 was obtained. Comparing the spectral reflection characteristics of the thin film layer of the surface 12e with the spectral reflection characteristics of the thin film layers of the other surfaces 12a to 12d, the difference in peak wavelength that maximizes the amount of reflected light is only 10 nm. It was 5%. From this result, it is confirmed that even if the underlying substrate on which the film is formed has some unevenness, the spectral reflection characteristics do not change extremely locally, and the shape of the underlying substrate has a certain degree of freedom. I was able to.
　さらに、上記試験成膜によって得られた単層の窒化チタン膜について、膜厚や分光透過率、分光反射率を測定し、既知のデータ、例えば成膜前のサンプル１２の表面反射率や膜厚などを考慮し、窒化チタン膜の分光反射特性を波長ごとに解析してその屈折率ｎと消衰係数ｋの値を計算によって求めた。算出された屈折率ｎと消衰係数ｋの値は図８に示すとおりで、それぞれに波長依存性のあることが確かめられた。なお、同図中、実線はサンプル１２の基板温度を先の成膜条件のとおり３００°Ｃにした場合の結果で、破線は上記成膜条件の中で基板温度だけを１５０°Ｃにしたときのものである。屈折率ｎと消衰係数ｋは、波長λに対して関数変化（Ｙ＝ａＸ３＋ｂＸ２＋ｃＸ＋ｄ）していることがわかる。 Further, the film thickness, spectral transmittance, and spectral reflectance of the single layer titanium nitride film obtained by the above test film formation are measured, and known data, for example, the surface reflectance and film thickness of the sample 12 before film formation are measured. In consideration of the above, the spectral reflection characteristics of the titanium nitride film were analyzed for each wavelength, and the values of the refractive index n and the extinction coefficient k were obtained by calculation. The calculated values of the refractive index n and the extinction coefficient k are as shown in FIG. 8, and it was confirmed that each has wavelength dependency. In the figure, the solid line is the result when the substrate temperature of sample 12 is set to 300 ° C. as in the previous film formation conditions, and the broken line is the result when only the substrate temperature is set to 150 ° C. in the above film formation conditions. belongs to. It can be seen that the refractive index n and the extinction coefficient k have a function change (Y = aX 3 + bX 2 + cX + d) with respect to the wavelength λ.
　以上の解析で得られた屈折率ｎ及び消衰係数ｋを用い、暗く沈んだ赤色反射光を得るために中心波長λ０＝５６０ｎｍで薄膜設計を行って表１の膜構成を得たが、この膜構成で成膜した装飾コーティング２により図２の分光反射特性が得られたことから、試験成膜に基づく屈折率ｎ及び消衰係数ｋの値に信頼性がもてること、そして薄膜設計手順に誤りがないことが確認できた。図２に示す分光反射特性を得るには、図８の測定結果からわかるように、３５０ｎｍ～８００ｎｍの波長域では窒化チタン膜の屈折率ｎが「２．０≦ｎ≦３．０」の範囲にあること、そして消衰係数ｋが「０．５≦ｋ≦１．５」の範囲にあることが必要である。 Using the refractive index n and the extinction coefficient k obtained by the above analysis, a thin film design was performed at the center wavelength λ 0 = 560 nm to obtain a darkly sunk red reflected light, and the film configuration of Table 1 was obtained. Since the spectral reflection characteristic shown in FIG. 2 is obtained by the decorative coating 2 formed in this film configuration, the refractive index n and the extinction coefficient k based on the test film formation are reliable, and the thin film design. It was confirmed that there were no errors in the procedure. In order to obtain the spectral reflection characteristics shown in FIG. 2, the refractive index n of the titanium nitride film is in the range of “2.0 ≦ n ≦ 3.0” in the wavelength range of 350 nm to 800 nm, as can be seen from the measurement result of FIG. And the extinction coefficient k needs to be in the range of “0.5 ≦ k ≦ 1.5”.
　窒化チタン膜と窒化シリコン膜とを用いた上記干渉薄膜層Ｌｓは、窒化チタン膜は窒化シリコン膜に対して高屈折率の薄膜として用いられている。その目的からは、屈折率ｎは高い方が好ましく、屈折率ｎが上記下限値を下回ると波長選択性のある分光反射特性が得にくくなり、所望の特性を得るには薄膜の積層数が増えて製造コストが高くなる不利がある。また、窒化チタン膜と窒化シリコン膜以外の誘電体層あるいは金属薄膜層であっても、少なくとも高低二種類の薄膜層の組み合わせにより同様の干渉薄膜層を得ることも可能であるが、そのためには複素屈折率Ｎ＝ｎ－ｉｋで表されるいずれかの薄膜について、
　　　１．３６≦ｎ≦３．５
　　　０．１≦ｋ≦６
を満たすようにするのが実用的である。屈折率ｎが上記下限値を下回ると波長選択性のある分光反射特性が得にくくなり、所望の特性を得るには薄膜の積層数が増えて製造コストが高くなる振りがある。逆に、屈折率ｎとして上限値を上回るような値を得ようとすると、その成膜条件を安定に保つことが難しく、屈折率ｎの値だけでなく消衰係数ｋの値も不安定になって工業的な製造には不向きとなる。また、消衰係数ｋが上記範囲から外れると反射光量の制御が難しくなり、沈んだ色合いの適度な強度の反射光が得にくくなる。 In the interference thin film layer Ls using a titanium nitride film and a silicon nitride film, the titanium nitride film is used as a thin film having a higher refractive index than the silicon nitride film. For that purpose, it is preferable that the refractive index n is high. When the refractive index n is below the lower limit, it becomes difficult to obtain spectral reflectance characteristics with wavelength selectivity, and the number of thin films increases in order to obtain desired characteristics. This has the disadvantage of increasing manufacturing costs. In addition, it is possible to obtain a similar interference thin film layer by combining at least two types of high and low thin film layers, even if it is a dielectric layer or metal thin film layer other than titanium nitride film and silicon nitride film. For any thin film represented by a complex refractive index N = n−ik,
1.36 ≦ n ≦ 3.5
0.1 ≦ k ≦ 6
It is practical to satisfy. If the refractive index n is lower than the lower limit, it becomes difficult to obtain spectral reflectance characteristics having wavelength selectivity, and there is a tendency that the number of thin film layers increases and the manufacturing cost increases in order to obtain desired characteristics. Conversely, if it is attempted to obtain a value that exceeds the upper limit as the refractive index n, it is difficult to keep the film forming conditions stable, and not only the value of the refractive index n but also the value of the extinction coefficient k becomes unstable. It becomes unsuitable for industrial production. Further, when the extinction coefficient k is out of the above range, it is difficult to control the amount of reflected light, and it becomes difficult to obtain reflected light with a moderate intensity with a sunken color.
　誘電体膜の場合、消衰係数ｋの値は可視光域では高々「２．０」程度のものが多いが、金属膜では表１に挙げたアルミニウムの薄膜にみられるように、消衰係数ｋが中心波長λ０で「５．６３１９２」にも達する。また、光透過性をもつ薄い膜厚の範囲内では屈折率ｎ＝０．８３４１３として膜計算を行うことも可能であることから、金属膜の積層により同様の干渉薄膜層Ｌｓを設計することが可能となる。 In the case of a dielectric film, the extinction coefficient k has a value of about “2.0” at most in the visible light range, but the metal film has an extinction coefficient as seen in the aluminum thin films listed in Table 1. k reaches “5.61922” at the center wavelength λ 0 . In addition, since it is possible to perform film calculation with a refractive index n = 0.83413 within a range of a thin film having light transmittance, it is possible to design a similar interference thin film layer Ls by stacking metal films. It becomes possible.
　以下に示す表２は、クロム（Ｃｒ）と金（Ａｕ）との二種類の金属膜を積層した干渉薄膜層の膜構成の一例（中心波長λ０＝５５０ｎｍ）を示すもので、その分光反射特性は図９のとおりである。この分光反射特性によれば、金属膜を用いながらも全体的な反射光量が短波長側でも高々３５％程度で、淡いシアン系の色が暗く沈んで観察され、独特の色合いが得られることがわかる。このような金属膜を利用した態様においても、一方の薄膜の屈折率ｎが「１．３６～３．５」の範囲にあり、消衰係数ｋが「０．１～６」の範囲にあることが満たされている。 Table 2 shown below shows an example of a film configuration of an interference thin film layer in which two kinds of metal films of chromium (Cr) and gold (Au) are laminated (center wavelength λ 0 = 550 nm), and its spectral reflection The characteristics are as shown in FIG. According to this spectral reflection characteristic, even though a metal film is used, the total amount of reflected light is about 35% at the short wavelength side, and a light cyan color is observed sunk darkly, and a unique hue can be obtained. Recognize. Also in the embodiment using such a metal film, the refractive index n of one thin film is in the range of “1.36 to 3.5”, and the extinction coefficient k is in the range of “0.1 to 6”. That is satisfied.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　また本発明の光学干渉薄膜は、例えばプラスチック製品の表面に形成する際に、製品の筐体そのものの表面に直接的に成膜するだけでなく、製品の筐体がプラスチックの成形品である場合にはいわゆるインサート成形手法を用いることもできる。図１０はその工程を概略的に示すものである。図１０（Ａ）に示す工程では、光学干渉薄膜の支持体となるベースフイルム２０に剥離可能な接着剤層２１を塗布し、その下層に光学干渉薄膜を保護するためのハードコート層２２を成膜しておく。ベースフイルム２０には、ＰＥＴ（ポリエチレンテレフタレート）製のシートを好適に用いることができる。図１０（Ｂ）に示す工程でハードコート層２２の下層に光学干渉薄膜２４を成膜する。その後、図１０（Ｃ）の工程で、図１０（Ｂ）までの工程で得られた積層体を製品の筐体サイズに合わせてカットされ、インサート部品２５が得られる。 Further, when the optical interference thin film of the present invention is formed on the surface of a plastic product, for example, it is not only directly formed on the surface of the product housing itself, but also the product housing is a plastic molded product. A so-called insert molding technique can also be used. FIG. 10 schematically shows the process. In the step shown in FIG. 10A, a peelable adhesive layer 21 is applied to a base film 20 that serves as a support for the optical interference thin film, and a hard coat layer 22 for protecting the optical interference thin film is formed thereunder. Keep a film. For the base film 20, a sheet made of PET (polyethylene terephthalate) can be suitably used. In the step shown in FIG. 10B, an optical interference thin film 24 is formed under the hard coat layer 22. Thereafter, in the step of FIG. 10C, the laminated body obtained in the steps up to FIG. 10B is cut according to the housing size of the product, and the insert part 25 is obtained.
　図１０（Ｄ）に示すように、インサート部品２５の光学干渉薄膜２４の表裏を反転させて下金型２６にインサートしてから上金型２７を合わせ、矢印に示すように溶融したプラスチックを両金型間のキャビティに射出して筐体２８を成形する。これにより、インサート部品２５は筐体２８とともに一体に成形される。図１０（Ｅ）の工程では、金型から取り出した成形品から接着剤層２１とともにベースフイルム２０を剥離する。これにより、最終的には筐体２８の表面に、保護用のハードコート層２２で覆われた光学干渉薄膜２４が形成される。 As shown in FIG. 10 (D), the front and back of the optical interference thin film 24 of the insert part 25 are reversed and inserted into the lower mold 26, and then the upper mold 27 is aligned. The casing 28 is molded by injection into a cavity between the molds. Thereby, the insert part 25 is integrally formed with the housing 28. 10E, the base film 20 is peeled off together with the adhesive layer 21 from the molded product taken out from the mold. As a result, an optical interference thin film 24 covered with the protective hard coat layer 22 is finally formed on the surface of the housing 28.
　以上、図示の実施形態に基づいて本発明について説明してきたが、干渉薄膜層Ｌｓの膜構成を変えることによって、様々な色光を暗く反射させる分光反射特性を得ることが可能である。また、表１に示す膜構成であればリアクティブスパッタ法による成膜でも図２と同様の分光反射特性が得られており、成膜方法としてもイオンプレーティング以外の種々の方法を用いることができる。さらに、金属膜の成膜には真空成膜はもとよりメッキを利用することも可能で、ほぼ同等の屈折率ｎと消衰係数ｋを得ることができる。 As described above, the present invention has been described based on the illustrated embodiment. However, by changing the film configuration of the interference thin film layer Ls, it is possible to obtain spectral reflection characteristics that darkly reflect various color lights. Further, in the case of the film configuration shown in Table 1, the spectral reflection characteristics similar to those in FIG. 2 can be obtained even by film formation by the reactive sputtering method, and various methods other than ion plating can be used as the film formation method. it can. Furthermore, in addition to vacuum film formation, plating can be used for forming a metal film, and an approximately equivalent refractive index n and extinction coefficient k can be obtained.
　１０　真空槽
　１１　基板ホルダ
　１２　サンプル
　１５　蒸発源 10 Vacuum chamber 11 Substrate holder 12 Sample 15 Evaporation source

Claims (8)

  1. 　下地基板側に形成され屈折率ｎが異なる少なくとも２種類の薄膜を積層した干渉薄膜層と、この干渉薄膜層を覆う透明な保護層とを有する光学干渉薄膜であり、
    　前記干渉薄膜層を構成するいずれかの薄膜の複素屈折率Ｎを、屈折率ｎ、消衰係数ｋ、虚数ｉを用いてＮ＝ｎ－ｉｋとしたとき、
    　　　１．３６≦ｎ≦３．５
    　　　０．１≦ｋ≦６
    を満たす光学干渉薄膜。     An optical interference thin film having an interference thin film layer formed by laminating at least two types of thin films having different refractive indexes n formed on the base substrate side, and a transparent protective layer covering the interference thin film layer;
    When the complex refractive index N of any thin film constituting the interference thin film layer is N = n−ik using the refractive index n, the extinction coefficient k, and the imaginary number i,
    1.36 ≦ n ≦ 3.5
    0.1 ≦ k ≦ 6
    An optical interference thin film that meets the requirements.
  2. 　前記保護層は、屈折率が１．３５～１．６５、膜厚が０．３～１００μｍの膜である請求の範囲第１項記載の光学干渉薄膜。 2. The optical interference thin film according to claim 1, wherein the protective layer is a film having a refractive index of 1.35 to 1.65 and a film thickness of 0.3 to 100 μm.
  3. 　前記保護層の上に、膜厚が３～５０μｍの透明なテフロン（登録商標）系またはシリコン系の塗装材料からなる汚れ防止層を設けた請求の範囲第２項記載の光学干渉薄膜。 3. The optical interference thin film according to claim 2, wherein a stain prevention layer made of a transparent Teflon (registered trademark) or silicon coating material having a thickness of 3 to 50 μm is provided on the protective layer.
  4. 　前記下地基板の表面に金属層が形成され、この金属層の上に前記干渉薄膜層が積層された請求の範囲第１項記載の光学干渉薄膜。 The optical interference thin film according to claim 1, wherein a metal layer is formed on a surface of the base substrate, and the interference thin film layer is laminated on the metal layer.
  5. 　前記干渉薄膜層が、窒化チタン膜を含む請求の範囲第１項記載の光学干渉薄膜。 The optical interference thin film according to claim 1, wherein the interference thin film layer includes a titanium nitride film.
  6. 　前記干渉薄膜層が、窒化シリコン膜を含む請求の範囲第５項記載の光学干渉薄膜。 The optical interference thin film according to claim 5, wherein the interference thin film layer includes a silicon nitride film.
  7. 　前記干渉薄膜層が、窒化チタン膜と窒化シリコン膜とを交互に積層した薄膜層である請求の範囲第６項記載の光学干渉薄膜。 The optical interference thin film according to claim 6, wherein the interference thin film layer is a thin film layer in which a titanium nitride film and a silicon nitride film are alternately laminated.
  8. 　前記干渉薄膜層が、屈折率ｎ及び消衰係数ｋが互いに異なる２種類の金属薄膜を交互に積層した薄膜層であり、前記保護膜が窒化チタン膜である請求の範囲第１項記載の光学干渉薄膜。 2. The optical device according to claim 1, wherein the interference thin film layer is a thin film layer in which two types of metal thin films having different refractive indexes n and extinction coefficients k are alternately stacked, and the protective film is a titanium nitride film. Interference thin film.
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