JP5860335B2 - Reflective film laminate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a reflective film laminate and a method for producing the same, and relates to a reflective film laminate useful as a reflective film for, for example, a vehicular lamp, a lighting fixture, and an optical mirror, and a method for producing the same.

  Since pure Al film has a high reflectance (88% to 90%), it is used as a reflective film for vehicle lamps, lighting fixtures, ornaments and the like. In general, the durability required for the reflective film includes acid resistance, alkali resistance, hot water resistance, heat resistance, moisture resistance, sulfidation resistance, salt water resistance, and the like. Since Al is an amphoteric metal, a pure Al film has low acid resistance and alkali resistance among the above characteristics, and particularly low alkali resistance. Therefore, when a reflective film made of a pure Al film (pure Al reflective film) is used for a vehicle lamp or the like, there is a problem that the reflective film deteriorates in a short period of time and a high reflectance cannot be maintained over a long period of time. .

  As a method for maintaining the high reflectivity of a pure Al reflective film for a long period of time, there has been proposed a method for improving corrosion resistance by using an Al alloy reflective film in which an alloy element is added to pure Al. For example, Patent Documents 1 and 2 disclose that when an Al—Mg alloy reflective film containing Mg is formed, a barrier film is formed on the surface, the corrosion resistance is improved, and the reflectance is not lowered over a long period of time. .

  The Al—Mg alloy reflective film in Patent Documents 1 and 2 has a concept that the corrosion resistance is realized only by the surface barrier film (passive film), and this barrier film has Al on the outermost surface of the reflective film in a corrosive environment. The Mg remaining after elution is concentrated (specifically, this Mg forms an insoluble compound on the outermost surface of the reflective film).

  As described above, the Al—Mg alloy reflective film exhibits corrosion resistance by forming a passive film in a corrosive environment, but it is difficult to form a strong film over the entire reflective film as the passive film. There is a problem in that Al is likely to be eluted from a portion where the concentration of water is insufficient, and as a result, the reflectance decreases.

  Mg forms an insoluble compound in a corrosive environment such as an alkaline aqueous solution, but reacts actively with warm water in a neutral region to generate hydrogen. When the generation of hydrogen occurs on the surface or inside of the reflective film, the reflective film is easily peeled off from the substrate or the like, so that there is a problem that the area of the reflective film is reduced and the reflectance is lowered. The reaction with the warm water in the neutral region becomes more remarkable as the amount of Mg added to Al increases, and becomes more prominent when the amount of Mg exceeds approximately 10 atomic%.

  On the other hand, when the amount of Mg in the Al—Mg alloy reflective film is suppressed to a level that does not cause a reaction with the warm water in the neutral range, the formation of the above-described passive film becomes insufficient and defects such as pinholes occur. When defects such as pinholes are present in the passive film, there is a problem that the Al-Mg alloy reflective film is corroded through the defective portion and the reflectance is lowered. Such a problem can be seen not only in a vehicular lamp but also in a lighting fixture or an optical mirror.

  Therefore, it is considered that there is a limit to ensuring durability when exposed to both corrosive environment and neutral hot water environment with the Al—Mg alloy reflective film alone.

JP 2007-72427 A Japanese Patent No. 4621989

  The present invention has been made under the circumstances as described above, and its purpose is to exhibit high reflectivity and durability [particularly resistance to alkaline solutions and resistance to warm water in a neutral range (hereinafter referred to as It is excellent in "warm water resistance")], and even when exposed to an alkaline environment and a hot water immersion environment, a reduction in reflectance is suppressed, and a reflective film laminate that can maintain a high reflectance is produced. It is often provided at low cost.

  The reflective film laminate of the present invention that has solved the above problems is formed on a substrate, and is an Al—Mg alloy containing 10 to 20 atomic% of Mg as a first layer in order from the substrate side. The second layer is characterized in that it has a metal oxide film containing Zr of 80 atomic% or more as the second layer, and the second layer has a thickness of 1.0 to 5 nm.

  The second layer is preferably a Zr oxide film.

The reflective film laminate of the present invention has an initial reflectance of 85.0% or more and is immersed in a 1% by mass potassium hydroxide aqueous solution at 25 ° C. for 10 minutes and in ion-exchanged water at 40 ° C. In any case after immersion for 30 hours, the density of the pinholes existing on the surface where the second layer of the reflective film laminate is formed is 1 / cm ² or less, and the diameters of all the pinholes Is also characterized in that is 1 mm or less.

  The present invention also includes a manufacturing method of the reflective film laminate, which includes the step of forming the first layer on a substrate; and the sputtering including the metal Zr on the first layer. And forming a second layer by oxidizing the sputtered metal thin film in an oxygen-containing atmosphere and then forming the second layer.

  The present invention also includes a vehicular lamp, a lighting fixture, and an optical mirror characterized by including the reflective film laminate.

  In the reflective film laminate of the present invention, an Al—Mg alloy layer is formed as the first layer, and a Zr-containing metal oxide film having as few pinholes as possible is formed as the second layer. As a result, since the portion where the first layer is exposed to the alkaline environment in an alkaline environment is limited to the pinhole portion, Mg concentration is concentrated in the pinhole portion, and the alkali resistance is dramatically increased. I think that. Moreover, since the exposed area of the first layer is extremely small, it is excellent in hot water resistance. Therefore, the high reflectance exhibited by the Al—Mg alloy layer can be maintained over a long period of time.

  The inventors of the present invention are Al-based reflective films that exhibit high reflectivity required for vehicular lamps, lighting fixtures, optical mirrors, and the like, and not only for alkaline solutions but also for neutral warm water. Intensive research was conducted in order to achieve a high-productivity and low-cost reflective film laminate that exhibits excellent resistance and can maintain the high reflectivity for a long period of time.

  As a result, it is a reflective film laminate formed on the substrate, and in the order from the substrate side, an Al—Mg alloy film containing 10 to 20 atomic% of Mg is formed as the first layer, and as the second layer, It has been found that a metal oxide film containing a predetermined amount of Zr may be formed to have a predetermined film thickness, and the present invention has been completed.

  In the present specification, the term “on the substrate” or “on the first layer” described later refers to the case where the first layer and the second layer are provided directly on the substrate or the first layer, and other films. The case where it is provided via is included.

  Hereinafter, the reflective film laminate of the present invention will be described in detail.

[First layer]
In the present invention, an Al—Mg alloy film containing 10 to 20 atomic% of Mg is provided on the substrate as a layer (first layer) responsible for high reflectivity.

  As described above, the reflectance of the pure Al film is 88 to 90%, which is higher than that of other general metal materials. However, pure Al is easily dissolved in an alkaline solution, and Al is eluted in an alkaline environment, resulting in a decrease in reflectance. Specifically, Al in the Al-Mg alloy reflective film elutes, the reflective film becomes thin, or the constituent components of the reflective film are lost from the substrate, and the reflective film becomes transparent, As a result, the reflectance decreases.

Therefore, in the present invention, an Al—Mg alloy film containing a certain amount of Mg is used. Mg forms an insoluble compound in an alkaline environment as described above. Specifically, it is considered that the alkali resistance of the Al—Mg alloy film is improved by forming insoluble Mg (OH) _{2 on the} surface of the Al—Mg alloy film. In order to effectively exhibit such an action, in the present invention, the amount of Mg in the Al—Mg alloy film is set to 10 atomic% or more. Preferably it is 11 atomic% or more. On the other hand, when the amount of Mg increases, the alkali resistance is improved, but as described above, the warm water resistance decreases, the corrosion occurs such that hydrogen is generated by reacting with the warm water, the reflection film peels off, etc. The film becomes transparent and, as a result, the reflectivity decreases. Therefore, the upper limit of Mg content is 20 atomic%. Preferably it is 19 atomic% or less.

  The components of the first layer are the remaining Al and inevitable impurities other than Mg.

  In addition, as an element that can be contained in addition to the Mg, a rare earth element may be contained in a range that does not impair the high reflectivity of the first layer, from the viewpoint of further increasing the alkali resistance of the first layer.

  The amount of Mg in the Al—Mg alloy film as the first layer can be measured by ICP (Inductively Coupled Plasma) emission spectrometry or ICP mass spectrometry.

  The film thickness of the first layer is preferably in the range of 50 to 500 nm from the viewpoint of ensuring high reflectivity of the reflective film laminate. If it is less than 50 nm, the film becomes translucent and does not reflect light completely, so the reflectivity tends to decrease. Therefore, the film thickness of the first layer is preferably 50 nm or more, and more preferably 100 nm or more. On the other hand, even if the film thickness is increased to more than 500 nm, the effect of improving the reflectance is saturated, but the productivity is lowered. Therefore, the film thickness of the first layer is preferably 500 nm or less, and more preferably 400 nm or less.

[Second layer]
As described above, even if the amount of Mg in the Al—Mg alloy film is increased, it is difficult to form a strong passive film over the entire reflective film, and in fact, Mg is not sufficiently concentrated (formation of the passive film). Corrosion spreads from this part, and as a result, the film becomes transparent and the reflectivity decreases. Further, as described above, Mg is an element effective for ensuring alkali resistance, but is an element that lowers hot water resistance.

  Therefore, in the present invention, a metal oxide film containing a predetermined amount of Zr is formed as a protective film (second layer) on the first layer (on the surface opposite to the substrate), thereby providing excellent alkali resistance and resistance. Try to combine warm water.

  Zr is an element that has a PB ratio (Pilling-Bedworth ratio: volume of metal oxide per unit mole / volume of the metal per unit mole) larger than 1, and causes volume expansion when oxidized. By using this Zr, the effect of sealing pinholes during oxidation can be expected. In addition, since Zr exhibits excellent durability (resistance to alkali, acid, and neutral warm water) compared to metals such as Ta, Nb, and Ti, the second layer itself deteriorates or the second layer There is no possibility that the first layer will deteriorate due to deterioration.

  The second layer of the present invention is mainly composed of Zr “oxide”. Since the Zr metal film has low transparency, when the Zr metal film is laminated on the first layer exhibiting high reflectivity, the reflectivity of the reflection film laminate is impaired. Since the second layer of the present invention mainly composed of is highly transparent, it is possible to prevent the reflectance of the reflective film laminate from being lowered.

  Although details are unknown about the mechanism in which the reflective film laminate of the present invention including the first layer and the second layer exhibits excellent alkali resistance and hot water resistance, it is presumed as follows. That is, the second layer of the present invention exhibits high alkali resistance. Further, the second layer of the present invention manufactured by the method of the present invention described later has as few pinholes as possible, but by forming the second layer with as few pinholes as possible on the first layer, Since the area where the first layer is exposed to the alkaline environment is extremely small and is limited to the pinhole portion, the above-described concentration of Mg is concentrated in the pinhole portion, and the alkali resistance is considered to increase dramatically. Also, even in a neutral hot water environment, the second layer does not react and the second layer is formed as a protective film for the first layer, so that the exposed area of the first layer is extremely reduced. As a result, it is considered that generation of hydrogen is suppressed and peeling of the reflective film can be prevented.

  In order to obtain both the alkali resistance improvement effect and the warm water resistance improvement effect, the second layer needs to be a metal oxide film containing 80 atomic% or more of Zr. A metal oxide film containing 90 atomic% or more of Zr is preferable, and an oxide film having a Zr content of 100 atomic% in the metal element, that is, a Zr oxide is more preferable.

  The amount of Zr in the second layer can be measured by ICP emission spectrometry or ICP mass spectrometry.

  In this specification, “an oxide film of“ metal containing 80 atomic% or more of Zr ”” means that 80 atomic% or more of all metal elements contained in the oxide film of the second layer is Zr. Means. The metal element contained in the oxide film may be composed of only Zr, or other elements may be contained together with Zr as long as the above-described effects of Zr are not impaired. Examples of the “other elements” include Ti, Al, Fe, Cu, and Mg.

  Further, in the present invention, the “metal oxide film” containing 80 atomic% or more of Zr is a metal oxide film oxidized throughout the film thickness direction, ensuring high durability and high reflectance. However, in the present invention, an unoxidized metal component may remain as long as the reflectance is not lowered.

  The film thickness of the second layer is 1.0 to 5 nm. When the film thickness is too thin, the durability improving effect due to the provision of the second layer may not be sufficiently exhibited. Therefore, the thickness of the second layer is 1.0 nm or more. Preferably it is 1.5 nm or more, More preferably, it is 2 nm or more. As the thickness of the second layer increases, the pinhole size becomes smaller, so that the pinhole can be easily sealed, and the Mg concentration in the pinhole portion becomes more effective, further improving the alkali resistance. Can be expected.

  However, if the film thickness of the second layer is too thick, it becomes difficult to oxidize the sputtered metal thin film over the entire film thickness direction in the second layer forming process in the manufacturing process, and as a result, the film becomes sufficiently transparent. In some cases, the reflectivity of the reflective film stack may decrease. Therefore, in the present invention, the thickness of the second layer is 5 nm or less. By setting it within this range, the second layer having high transparency can be formed by being oxidized over the entire film thickness direction in the manufacturing process, and as a result, a decrease in reflectance of the reflective film laminate can be prevented. The film thickness of the second layer is preferably 4.5 nm or less, more preferably 4.0 nm or less.

[Substrate]
The base material for forming the reflective film laminate of the present invention is not particularly limited as long as it is usually used in the fields of lighting equipment, vehicular lamps, optical mirrors and the like. Examples of the material of the base include resin and glass. Examples of the resin include polycarbonate resins, acrylic resins, polyester resins such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate), ABS resins, epoxy resins, acetal resins, and alicyclic hydrocarbon resins. A mixture of these resins may be used.

  In the present invention, it is preferable to determine the material of the substrate in accordance with the temperature of heat generated by the light source. For example, when the temperature of the light source is about 180 ° C. or higher, the use of glass is preferable, when about 120 to 180 ° C., the use of polyester resin such as PET or PBT is preferable, and when the temperature is about 120 ° C. or lower, the use of polycarbonate resin is preferable. Is preferred.

  Moreover, you may use the resin material whose water absorption rate is less than 0.1% when it measures by A method (method which measures water absorption after being immersed in 23 degreeC pure water for 24 hours) prescribed | regulated to JISK7209. If a substrate excellent in moisture resistance (waterproofness) (substrate having a low water absorption rate) is used in this way, moisture contained in the substrate and the back surface of the substrate (the side on which the Al-Mg alloy film of the present invention is not formed) In this case, it is possible to suppress a decrease in reflectivity of the Al—Mg alloy film due to moisture that has entered from the surface, and thus a reflective film laminate having excellent moisture resistance can be obtained. Examples of the resin that satisfies this requirement include PET resin (water absorption rate 0.05%), PPS (polyphenylene sulfide) resin (water absorption rate 0.03%), and the like. The preferable water absorption rate of the substrate is 0.08% or less, more preferably 0.06% or less.

[Third layer; other layers]
A typical example of the reflective film laminate of the present invention is one in which the first layer and the second layer are sequentially laminated directly on the substrate, but is not limited thereto.

  For example, an adhesion improving layer may be provided between the base and the first layer as necessary. An Al oxide film may be formed between the first layer and the second layer. Even if an Al oxide film is present, the durability and reflectivity of the reflective film laminate of the present invention are not lowered.

  Further, on the second layer (the surface opposite to the first layer forming surface, the outermost surface), the durability of the reflective film laminate of the present invention is further improved, and the high reflectance is maintained for a long time. For the purpose, a known plasma polymerization film or resin film may be provided.

  Examples of the plasma polymerized film include a mode in which a plasma polymerized film is formed using organic silicon. Examples of the organic silicon include hexamethyldisiloxane, hexamethyldisilazane, and triethoxysilane. The preferable film thickness of the plasma polymerized film is 5 to 500 nm, and the more preferable film thickness is 10 to 400 nm. When the film thickness is reduced, the barrier property is decreased. On the other hand, when the film thickness is increased, the film stress is increased, and there is a possibility that cracking or peeling may occur when a heat resistance test or a moisture resistance test is performed after stacking.

  Examples of the resin film include those made of acrylic resin, silicone resin, or the like. A preferable film thickness of the resin film is 0.1 to 20 μm. The problem that occurs when the film thickness is out of the range is the same as the plasma polymerization film.

[Characteristics and uses of reflective film laminates]
Since the reflective film laminate of the present invention has the above-described configuration, it exhibits high reflectivity and excellent durability (alkali resistance and warm water resistance). In particular, since the reflective film laminate of the present invention has a very high reflectance, if the reflective film laminate of the present invention is used for a vehicle lamp, a lighting fixture, an optical mirror, or the like, it consumes a light source (lamp). Even if the power is lowered from the conventional level, the same level of brightness can be ensured. Further, when a plurality of lamps are used, the number of lamps can be reduced, so that the cost for the light source can be reduced.

  Here, the vehicular lamp means a head lamp, a rear lamp, or the like of an automobile or a motorcycle. The reflective film laminate of the present invention is suitably used for the reflector and extension of these lamps. A lighting fixture means a downlight or a fluorescent lamp. The lighting fixture includes a lighting fixture using an LED or an organic EL as a light source. The optical mirror means a mirror of an electronic flash of a camera, a mirror in an analyzer using light reflection, or the like.

[Production Method of Reflective Film Laminate]
The production method of the reflective film laminate of the present invention is as follows:
Forming the first layer on a substrate;
A sputtered metal thin film is formed on the first layer by sputtering using a sputtering target containing metal Zr, and then the sputtered metal thin film is oxidized in an atmosphere containing oxygen to form the second layer. Process and;
Is included.

  In the manufacturing method of the present invention, as the second layer (metal oxide film) in the reflective film laminate, a pinhole is sufficiently sealed with a thickness of 1 to 5 nm. Rather than forming the metal oxide film directly on the first layer, first, a metal film containing Zr (sputtered metal thin film) is formed on the first layer, and this metal film is oxidized to form the second layer ( (Metal oxide film) is formed.

  The production method of the present invention will be described in detail below.

(Formation of the first layer)
The formation method of a 1st layer is not specifically limited, For example, forming by sputtering method is mentioned. When forming by sputtering, for example, an Al—Mg alloy sputtering target, a target in which metal Mg is embedded in a part of a pure Al sputtering target (so-called mosaic target), or a pure Al sputtering target and a metal are used. Sputtering may be performed using an Mg sputtering target at the same time, or using a metal Al chip placed on a pure Al sputtering target. As the sputtering method, a DC sputtering method using a direct current cathode is particularly preferable.

  As sputtering conditions, for example, film formation is performed at a DC sputtering power of 400 W, an Ar atmosphere, and a pressure of 0.26 Pa.

(Formation of the second layer)
In forming the second layer, first, a sputtering metal thin film is formed by sputtering using a sputtering target containing metal Zr (for example, a sputtering target containing metal Zr such as a metal Zr sputtering target or a Zr alloy sputtering target). As the sputtering method, a DC sputtering method using a direct current cathode is particularly preferable.

  As sputtering conditions, for example, film formation is performed at a DC sputtering power of 200 W, an Ar atmosphere, and a pressure of 0.26 Pa.

  Next, the sputtered metal thin film (Zr-containing metal film) is oxidized in an atmosphere containing oxygen, and in particular, the metal Zr is converted into a Zr oxide.

  In the present invention, “oxidize” is intended to include all aspects in which at least part of the sputtered metal thin film is exposed to an oxygen-containing atmosphere regardless of the intention of oxidation. For example, in addition to the case where the sputtered metal thin film is intentionally oxidized in an atmosphere containing oxygen, since Zr is a metal that is easily oxidized, a laminate in which the sputtered metal thin film is formed on the first layer is simply This includes cases where the sputtered metal thin film is oxidized as a result of being left in an atmosphere containing oxygen, for example, being kept in the air for a long time (usually about 24 hours) (that is, natural oxidation).

However, in the above natural oxidation method, since it takes a long time to oxidize the sputtered metal thin film, in order to promote the oxidation, it is preferable to hold it while performing a heat treatment at a high temperature (which may be lower than the heat resistant temperature of the substrate). Alternatively, the Zr-containing metal film is oxidized by a method in which the oxygen concentration is maintained in an atmosphere higher than that in the atmosphere (further, heat treatment may be performed at a high temperature) or an O ₂ plasma treatment used in semiconductor manufacturing. Also good. From the viewpoint of production cost, it is most preferable to oxidize by heat treatment in the atmosphere.

(Third layer; formation of other layers)
When a plasma polymerization film is further formed on the second layer, for example, a method of forming a film by a plasma CVD method using hexamethyldisiloxane as a raw material can be mentioned. Further, when a resin film is further formed on the second layer, for example, a method of forming by a dip or spray coating can be mentioned.

  What is necessary is just to manufacture these for the vehicle lamp of this invention, a lighting fixture, and an optical mirror by the method generally performed except manufacturing a reflective film part with the manufacturing method of the said invention.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

  Polycarbonate (PC) having a diameter of 50.8 mm and a thickness of 1 mm was used as the substrate.

  A first layer was formed directly on the PC substrate by the sputtering method described below. That is, as a sputtering target, a 10 mm square metal Mg chip placed on a pure Al sputtering target having a diameter of 101.6 mm and a thickness of 5 mm was used. The first layer (Al—Mg alloy film) having various compositions shown in Table 1 below was obtained by changing the position and number of metal Mg chips on the pure Al sputtering target.

Sputtering was performed as follows. First, it was evacuated so that the pressure in the sputtering chamber was 1 × 10 ⁻³ Pa or less. Next, Ar gas is introduced into the sputtering chamber, the pressure in the sputtering chamber is adjusted to 2.6 × 10 ⁻¹ Pa, DC (direct current) power 250 W is applied to the electrodes to generate plasma, and a sputtering target Was sputtered to form a first layer (pure Al and Al—Mg alloy film, film thickness 150 nm) on the PC substrate. The distance between the sputtering target and the PC substrate was 80 mm, and the PC substrate was formed while revolving.

Next, a second layer was formed on the first layer as follows. That is, after forming the first Al film, Ar gas is introduced into the sputtering chamber without opening the sputtering chamber so that the pressure in the sputtering chamber becomes 2.6 × 10 ⁻¹ Pa. A sputtered metal thin film was obtained by sputtering a metal Zr sputtering target having a diameter of 101.6 mm and a thickness of 5 mm at a DC power of 200 W. And it oxidized and the metal oxide film was obtained.

  In Example 7 and Comparative Example 7 in Table 1 below, a film was formed using a Ti chip placed on a metal Zr sputtering target instead of the metal Zr sputtering target. In Comparative Example 5 shown in Table 1 below, a film was formed using a metal Ti sputtering target instead of the metal Zr sputtering target. The oxidation treatment was held for 24 hours at room temperature in the atmosphere.

  The film thicknesses of the first layer and the second layer were adjusted by controlling the sputtering time.

  About the obtained reflection film laminated body, the component of the 1st layer and the 2nd layer was measured with the following method. Further, an alkali resistance test and a hot water resistance test were performed under the following conditions.

<Method for measuring components of first layer and second layer>
The amount of Mg in the Al—Mg alloy film was determined by measurement by ICP (Inductively Coupled Plasma) emission spectrometry or ICP mass spectrometry. Specifically, using an acid capable of dissolving both Al and Mg, the entire amount of the Al-Mg alloy film is dissolved, and the contents of Al and Mg in the obtained solution are determined by ICP emission spectrometry or ICP mass spectrometry. It was measured. Then, the amount of Mg (atomic%) was calculated when the total of Al and Mg was 100 atomic%.

  The component composition of the second layer was also determined by measurement by ICP (Inductively Coupled Plasma) emission spectrometry or ICP mass spectrometry.

  In the second layer forming step, since the oxidation treatment is performed after the sputtered metal thin film is formed, most of the metal elements contained in the second layer form oxides.

<Measurement of visible light reflectance (initial reflectance)>
By the method shown in JIS R 3106, light having a wavelength range of 380 to 780 nm of the D65 light source is incident on the surface of the reflective film stack (the surface on which the second layer is formed), and the visible light reflectance (initial (Reflectance) was measured. And the thing with the said reflectance of 85.0% or more was evaluated as a high reflectance.

<Alkali resistance evaluation test>
The reflective film laminate was immersed in a 1 mass% potassium hydroxide aqueous solution at room temperature (25 ° C.) for 10 minutes. And the surface (surface in which the 2nd layer is formed, the observation area is about 10 cm < ² >) of the reflecting film laminated body after immersion is in the state which irradiated light from the back surface (surface on the base | substrate side) of a reflecting film laminated body Thus, the degree of corrosion (pinhole-like corrosion) and transparency was confirmed by visual observation.

And it judged as follows and evaluated (double-circle) and (circle) that it was excellent in alkali resistance.
◎… No pinhole-like corrosion 〇… Pinhole-like corrosion exists, but the density of the pinhole-like corrosion is 1 piece / cm ² or less, and all pinhole-like corrosion The diameter of the pinhole-like corrosion is more than 1 piece / cm ² ; the diameter of the pinhole-like corrosion exceeds 1 mm; or the film is translucent; If it falls into at least one of the following: × ... If the membrane is completely transparent

<Hot water resistance evaluation test>
The reflective film laminate was immersed in ion exchange water (neutral) at 40 ° C. for 30 hours. And the surface (surface in which the 2nd layer is formed, the observation area is about 10 cm < ² >) of the reflecting film laminated body after immersion is in the state which irradiated light from the back surface (surface on the base | substrate side) of a reflecting film laminated body Thus, the degree of corrosion (pinhole-like corrosion) and transparency was confirmed by visual observation.

And it judged as follows and evaluated (double-circle) and (circle) that it was excellent in warm water resistance.
◎… No pinhole-like corrosion 〇… Pinhole-like corrosion exists, but the density of the pinhole-like corrosion is 1 piece / cm ² or less, and all pinhole-like corrosion The diameter of the pinhole-like corrosion is more than 1 piece / cm ² ; the diameter of the pinhole-like corrosion exceeds 1 mm; or the film is translucent; If it falls into at least one of the following: × ... If the membrane is completely transparent

  These results are shown in Table 1.

  From Table 1, it can be considered as follows.

  From Examples 1-7, it turns out that the reflective film laminated body of this invention has the outstanding initial stage reflectance, alkali resistance, and warm water resistance. In particular, from Example 7, if a metal oxide film containing 80 atomic% or more of Zr is formed as the second layer, sufficient durability can be exhibited. Preferably, if the second layer is a Zr oxide film, It can be seen that a product with better durability can be obtained.

  From the comparison between Examples 2, 4 and 6, and Examples 1, 3 and 5, it is effective to make the thickness of the second layer relatively thin within a specified range in order to obtain a higher reflectance. On the other hand, it can be seen that it is effective to relatively increase the thickness of the second layer within a specified range in order to ensure better alkali resistance.

  On the other hand, in Comparative Example 1, since the amount of Mg in the first layer is below the lower limit specified in the present invention, the reflection film laminate is made transparent in the alkali resistance evaluation test. In Comparative Example 2, the amount of Mg in the first layer exceeds the upper limit specified in the present invention, so that the initial reflectance is lowered and the hot water resistance is also inferior.

  Further, in Comparative Example 3, the initial reflectance is low because the film thickness of the second layer exceeds the upper limit specified in the present invention. Moreover, since the film thickness of the 2nd layer was too thin below the lower limit prescribed | regulated by this invention, the comparative example 4 was a result in which both alkali resistance and warm water resistance were inferior.

  Comparative Example 5 is a metal oxide (Ti oxide) film in which the second layer does not contain 80 atomic% or more of Zr, and pinholes exist, so even if the thickness of the second layer is increased, It turns out that there is a problem in durability (alkaline resistance and hot water resistance) essentially.

  Comparative Example 6 is inferior in alkali resistance because the first layer is a pure Al film.

  In Comparative Example 7, since the amount of Zr in the second layer was insufficient, the effect of forming the second layer was not sufficiently obtained, and excellent warm water resistance could not be ensured.

  INDUSTRIAL APPLICABILITY The present invention can provide a reflective film laminate that can enhance the durability of an Al-based reflective film exhibiting a high reflectance and maintain the high reflectance over a long period of time. Therefore, if the reflecting film laminate of the present invention is used for reflecting films such as a vehicular lamp, a lighting fixture, and an optical mirror, it is possible to expect improvement in durability.

Claims (7)

Formed on a substrate,
In order from the substrate side, the first layer has an Al-Mg alloy film containing 10 to 20 atomic% of Mg, and the second layer has a metal oxide film containing 80 atomic% or more of Zr,
And the film thickness of the said 2nd layer is 1.0-5 nm, The reflection film laminated body characterized by the above-mentioned.   The reflective film stack according to claim 1, wherein the second layer is a Zr oxide film. The initial reflectance is 85.0% or more, and
Either after being immersed for 10 minutes in a 1% by weight potassium hydroxide aqueous solution at 25 ° C. or after being immersed in ion exchange water at 40 ° C. for 30 hours,
The density of pinholes existing on the surface where the second layer of the reflective film laminate is formed is 1 / cm ² or less, and the diameter of all pinholes is 1 mm or less. The reflecting film laminated body of description. It is a manufacturing method of the reflective film layered product according to any one of claims 1 to 3,
Forming the first layer on a substrate;
A sputtered metal thin film is formed on the first layer by sputtering using a sputtering target containing metal Zr, and then the sputtered metal thin film is oxidized in an atmosphere containing oxygen to form the second layer. And a process for producing a reflective film laminate.   A vehicular lamp comprising the reflective film laminate according to claim 1.   A lighting apparatus comprising the reflective film laminate according to claim 1.   An optical mirror comprising the reflective film laminate according to claim 1.