JP2020024237A - Optical product - Google Patents

Abstract

To provide an optical product which can provide desired spectral characteristic while exhibiting a catalytic effect.SOLUTION: The optical product is provided that includes a glass substrate having a multilayer film of three or more layers formed thereon, the multilayer film is configured to adjust spectral characteristic of the optical product by combining at least one low refractive index layer with at least one high refractive index layer. The uppermost layer furthest from the glass substrate is a low refractive index layer, and a high refractive index layer next to the uppermost layer is a functional layer principally made of a photocatalytic metal oxide. The optical product satisfies the following conditional expressions: 60nm≤TL≤350nm ...(1), 220nm≤Tcat≤700nm ...(2), where TL represents a thickness of the uppermost layer, and Tcat represents a thickness of the functional layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical product having a multilayer film formed thereon.

  For example, titanium oxide is known to have a high photocatalytic effect. More specifically, when the titanium oxide is irradiated with UV light, the oxidation-reduction reaction is strongly promoted, and the surface of the titanium oxide exhibits a hydrophilic property that is easily wetted by water, and thus is washed with water drops such as rain. Is known to have a so-called self-cleaning action.

  For example, in Patent Document 1, a low-refractive-index layer and a high-refractive-index layer are alternately laminated, and the uppermost layer has a multilayer antireflection film that is a low-refractive-index layer. Articles are disclosed that are layers of metal oxides, such as titanium oxide or composite films containing titanium oxide having photocatalytic activity. Such articles can be used, for example, as lenses for glasses, cameras, binoculars, microscopes, and the like, and are said to be able to exhibit functions such as antifouling and antifogging. There is a demand that such a technology be applied to optical products such as a vehicle-mounted camera and a glass building material that are easily soiled and difficult for the user to clean.

JP 2000-329904 A

By the way, in the technique of Patent Document 1, the film thickness of TiO ₂ that exerts a photocatalytic function is 200 nm or less, and there is a possibility that a sufficient photocatalytic effect cannot be realized for an optical product placed in an environment that is easily contaminated. is there. On the other hand, if the film thickness of TiO ₂ is increased, the photocatalytic function can be exhibited to some extent, but there is also a problem that desired optical characteristics cannot be obtained.

  An object of the present invention is to provide an optical product that can obtain desired spectral characteristics while exhibiting a photocatalytic effect.

The optical product of the present invention is an optical product having a glass substrate on which three or more multilayer films are formed,
The multilayer film adjusts the spectral characteristics of the optical product by using at least one low-refractive-index layer and at least one high-refractive-index layer in combination.
The uppermost layer farthest from the glass substrate is the low refractive index layer,
The high refractive index layer adjacent to the uppermost layer is a functional layer mainly composed of a metal oxide having a photocatalytic function,
The following conditional expression is satisfied.
60 nm ≦ TL ≦ 350 nm (1)
220 nm ≦ Tcat ≦ 700 nm (2)
here,
TL: film thickness of the uppermost layer Tcat: film thickness of the functional layer

  According to the present invention, it is possible to provide an optical product that can obtain desired spectral characteristics while exhibiting a photocatalytic effect.

It is a figure which shows typically the cross section of the optical product concerning this Embodiment. It is a figure which shows the spectral characteristic of the multilayer film of test number 1-1 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 1-2 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 1-3 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 1-4 which is a comparative example. It is a figure which shows the spectral characteristic of the multilayer film of test number 1-5 which is a comparative example. It is a figure which shows the spectral characteristic of the multilayer film of test number 2-1 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 2-2 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 2-3 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 2-4 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 3-1 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of test number 3-2 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 3-3 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 3-4 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 4-1 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 4-2 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 4-3 which is an Example. It is a figure which shows the spectral characteristic of the multilayer film of sample number 4-4 which is an Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating a cross section of the optical product according to the present embodiment. The optical product shown in FIG. 1A has a multilayer film MC having a structure in which low refractive index layers L and high refractive index layers H are alternately laminated on a glass substrate GL. However, the high refractive index layer H may be in contact with the glass substrate GL. Such an optical product has a light transmission function and a reflection function, and can be used, for example, as a vehicle-mounted lens, a communication lens, and a building material. In FIG. 1, a layer located between the glass substrate and the functional layer may be replaced with an equivalent film of an intermediate refractive index layer instead of the high refractive index layer or the low refractive index layer.

  On the other hand, the optical product shown in FIG. 1B has a structure in which a metal film M is formed on a glass substrate GL, and a high refractive index layer H and a low refractive index layer L are alternately laminated thereon. It has a multilayer film MC. However, the high refractive index layer H may be in contact with the metal film M. Such an optical product has a light reflecting function and can be used as, for example, a reflector, a building material, or a vehicle-mounted mirror.

In FIG. 1, the uppermost layer farthest from the glass substrate GL is the low refractive index layer L, and the high refractive index layer H adjacent to the uppermost layer is a metal oxide functional layer having a photocatalytic function. By using the low refractive layer L having relatively high strength as the uppermost layer, scratch resistance can be improved. In addition, since the functional layer exerts a photocatalytic function using active oxygen excited by UV light through the uppermost layer, it is preferable to place the functional layer as close as possible to the uppermost layer. By providing a functional layer adjacent to the uppermost layer, for example, a photocatalytic function can be effectively exerted. It is desirable that the functional layer has a thickness of 100 nm or more adjacent to the uppermost layer. Further, by using a metal oxide having a photocatalytic effect and a photoactive effect, organic substances on the surface are removed and the hydrophilicity of the uppermost layer is improved. Is preferable because it can be maintained. The functional layer using TiO ₂ is preferably formed by using IAD because the photocatalytic effect is enhanced.

  The "photocatalytic function" means that strong oxidizing power is generated when sunlight or artificial light enters, and it is possible to effectively remove harmful substances such as organic compounds and bacteria that come in contact with it. A self-cleaning function that prevents water droplets from remaining on the surface and is washed with water or the like without fixing oily stains, etc., and is a function of, for example, titanium dioxide. In addition, “adjacent to the uppermost layer” means not only a case where the uppermost layer and the functional layer are in close contact with each other, but also a layer between the uppermost layer and the functional layer that can be regarded as not hindering the expression of the function (for example, 20 nm or less) Is included.

Further, the optical product of the present embodiment satisfies the following conditional expressions.
60 nm ≦ TL ≦ 350 nm (1)
220 nm ≦ Tcat ≦ 700 nm (2)
here,
TL: film thickness of the uppermost layer Tcat: film thickness of the high refractive index layer (functional layer) H adjacent to the uppermost layer

When the value of the expression (1) is equal to or less than the upper limit, a photocatalytic effect can be exhibited by exchanging active oxygen excited by UV light through the uppermost layer. On the other hand, when the value of the expression (1) is equal to or more than the lower limit, a strong top film can be formed, so that sufficient scratch resistance can be secured. Preferably, the following expression is satisfied.
220 nm ≦ Tcat ≦ 600 nm (2 ′)
More preferably, the following expression is satisfied.
60 nm ≦ TL ≦ 250 nm (1 ′)

When the value of the expression (2) is at least the lower limit, a sufficient photocatalytic effect can be expected because the thickness of the functional layer can be ensured. On the other hand, as the thickness of the functional layer increases, the photocatalytic effect can be expected. However, it is difficult to obtain a desired spectral characteristic required for the multilayer film. Is desirable. Preferably, the following expression is satisfied.
250 nm ≦ Tcat ≦ 600 nm (2 ″)

It is preferable that the high refractive index layer (functional layer) H adjacent to the uppermost layer is formed of an oxide containing Ti as a main component (for example, TiO ₂ ). This is because Ti oxide such as TiO ₂ has a very high photocatalytic effect.

Preferably the uppermost layer is formed of SiO _2. UV light is hardly incident at night or outdoors, and the hydrophilic effect of an oxide containing Ti as a main component is reduced. However, even in such a case, the hydrophilic effect can be exhibited by forming the uppermost layer from SiO ₂ , and the scratch resistance is improved. Can be further enhanced. When SiO ₂ is used for the uppermost layer, the scratch resistance is improved by performing a heat treatment at 500 ° C. for 2 hours after the film formation.

It is preferable that the uppermost layer is formed of a mixture of SiO ₂ and Al ₂ O ₃ (provided that the composition ratio of SiO ₂ is 90% by weight or more). Thereby, a hydrophilic effect can be exerted even at night or outdoors, and the scratch resistance can be further enhanced by using a mixture of SiO ₂ and Al ₂ O ₃ . When a mixture of SiO ₂ and Al ₂ O ₃ is used for the uppermost layer, the heat resistance is improved by performing a heat treatment at 500 ° C. for 2 hours after the film formation. Note that it is preferable to use ion-assisted deposition (IAD) when forming part or all of the uppermost layer. Thereby, the scratch resistance can be improved.

  The multilayer film MC is formed by a vapor deposition method, and any one of the layers is preferably formed by IAD. Shifting of spectral characteristics can be suppressed by film formation by IAD.

  The multilayer film MC shown in FIG. 1A preferably has antireflection characteristics in the visible region. Here, the “visible range” refers to a wavelength range of 420 nm to 680 nm. The “anti-reflection property” here means that the light reflectance in the visible region is 2% or less, preferably 1% or less, more preferably 0.5% or less. As a result, an antireflection effect in the visible region can be obtained, and it is suitable for use in an imaging lens or the like.

  The multilayer film MC shown in FIG. 1A or 1B preferably has a semi-transmissive or high-reflection characteristic in a visible light region. Here, the “semi-transmission characteristic” refers to a case where the light transmittance in the visible region is 30% or more and 70% or less, and the “high reflection characteristic” refers to a case where the light reflectance in the visible region is 90% or more. It means that. Thereby, a semi-transmissive mirror or a total reflection mirror in the visible region can be obtained.

  The multilayer film MC shown in FIG. 1A or 1B preferably has antireflection characteristics in the near infrared region. Here, the “near infrared region” refers to a wavelength range of 700 nm to 2000 nm. The “anti-reflection property” here means that the light reflectance in the near infrared region is 2% or less, preferably 1% or less, more preferably 0.5% or less. Thereby, an antireflection effect in the near infrared region can be obtained.

  The multilayer film MC shown in FIG. 1A or 1B preferably has a characteristic of reflecting 70% or more of near infrared light. Thereby, a reflection mirror in the near infrared region and an IR cut filter can be obtained.

  It is preferable that the multilayer film MC shown in FIG. 1A or 1B has a characteristic of reflecting 70% or more of ultraviolet light. Here, the "ultraviolet region" refers to a wavelength range of 350 nm to 400 nm. Note that the light reflectance in the ultraviolet region is desirably 90% or more, and more desirably 95% or more. Thereby, a reflection mirror in the ultraviolet region and an ultraviolet cut filter can be obtained.

  The multilayer film MC may include a metal film or a dielectric multilayer film that reflects at least one of visible light and near infrared light. Here, the “reflection characteristic” means that the light reflectance is 70% or more, preferably 85% or more in a visible region or a near-infrared region.

  When the metal film M is used, it is preferable that any one of Ag, Au, Cr, Al, Cu, and Ni be the main component. By appropriately using these, the usable range and the reflectance can be arbitrarily adjusted. The term "main component" means that the content of the element is 51% by weight or more, preferably 70% by weight or more, more preferably 90% by weight, and further preferably 100% by weight.

It is preferable that the optical product satisfies the following conditional expression.
1.3 ≦ NL ≦ 1.5 (3)
1.9 ≦ NH ≦ 2.45 (4)
here,
NL: refractive index at d-line of material of low refractive index layer NH: refractive index at d-line of material of high refractive index layer

By satisfying the expressions (3) and (4), an optical product having desired optical characteristics can be obtained. Here, the d-line refers to light having a wavelength of 587.56 nm. As a material of the low refractive index layer, SiO ₂ having a refractive index of 1.48 at d-line or MgF ₂ having a refractive index of 1.385 at d-line can be used. Further, as a specific material satisfying the expression (4), oxides of Ta, Hf, Zr, and Nb can be suitably used.

When the glass substrate GL has an optical power, it is preferable to satisfy the following conditional expression.
1.7 ≦ Ns ≦ 2.2 (5)
here,
Ns: refractive index of glass substrate GL at d-line

  By satisfying the expression (5) as the refractive index at the d-line of the glass substrate in the optical design, the optical performance of the optical product can be enhanced while having a compact configuration. By forming the multilayer film of the present invention on a glass substrate satisfying the expression (5), the multilayer film can be used particularly for a lens or the like exposed to the outside, thereby achieving both excellent environmental resistance performance and optical performance. it can.

On the other hand, when the glass substrate GL has no optical power, it is preferable that the following conditional expression is satisfied.
1.45 ≦ Ns ≦ 1.65 (6)
here,
Ns: refractive index of glass substrate GL at d-line

  This is because, when an optical product is applied as a building material such as a window glass, it is desirable to use a glass substrate having a refractive index of about 1.52, which is relatively inexpensive and has high strength.

According to this embodiment, the multilayer film uppermost SiO ₂ film thickness, density, and maximize the TiO ₂ film thickness optimized photocatalytic effect of the film forming formulations and the top layer to the adjacent functional layers, combined spectral By providing the characteristic adjustment layer, it is possible to provide a photocatalytic optical multilayer film having arbitrary spectral characteristics in a wavelength band ranging from a visible region to a near infrared region.

(Example)
Hereinafter, Examples suitable for the above-described embodiments will be evaluated in comparison with Comparative Examples. In forming the multilayer films of the following examples and comparative examples, a film forming apparatus BES-1300 manufactured by SYNCHRON CORPORATION was used, and NIS-175 was used as an ion source of IAD.

(Evaluation on the thickness of the functional layer)
The present inventors formed a nine-layered multilayer film on a glass substrate (refractive index: 1.804) having optical power by a vapor deposition method while changing the thickness (d (nm)) of the functional layer. For the test. More specifically, as shown in Table 1, a low refractive index layer using SiO ₂ and OA600 (manufactured by Canon Optron Co., Ltd.) were formed on a glass substrate TAF3 (manufactured by HOYA Corporation: refractive index 1.804). A high-refractive-index layer using a material (material) and a functional layer using TiO ₂ were stacked in the order shown in Table 1 to form a film. SiO ₂ was used as the uppermost layer. Table 1 shows the film forming recipe and the film configuration of each layer (the layer in contact with the glass substrate is referred to as a first layer, the same applies hereinafter).

OA600 is a mixture of Ta ₂ O ₅ , TiO, and Ti ₂ O ₅ , and its specific composition is mainly tantalum oxide as shown in Table 2.

The refractive index n (λ) in Table 1 and the table described later was determined by the following equation. In this specification, the refractive index is measured at d-line (wavelength: 587.56 nm).
n (λ) = A ₀ + A ₁ / (λ−A ₂ )
Here, λ is the wavelength of the d-line, and A ₀ , A ₁ , and A ₂ of the materials used in Examples and Comparative Examples are the following values, respectively.
_{TAF3: A 0 = 1.768, A} 1 = 14.724 (nm), A 2 = 181.535 (nm)
B270 (white plate): A0 = 1.504, A1 = 6.912 (nm), A2 = 193.866 (nm)
M-BACD12: A0 = 1.561, A1 = 9.387 (nm), A2 = 160.63 (nm)
_{OA600: A 0 = 2.014, A} 1 = 31.680 (nm), A 2 = 233.891 (nm)
SiO ₂ : A ₀ = 1.460, A ₁ = 0 (nm), A ₂ = 0 (nm)
H4: A ₀ = 2.100, A ₁ = 0 (nm), A ₂ = 0 (nm)
TiO ₂ (functional layer): A ₀ = 2.013, A ₁ = 36.149 (nm), A ₂ = 284.651 (nm)
TiO ₂ : (high refractive layer 1) A ₀ = 2.200, A ₁ = 71.220 (nm), A ₂ = 234.000 (nm)
TiO ₂ : (high refractive layer 2) A ₀ = 2.230, A ₁ = 71.220 (nm), A ₂ = 234.000 (nm)

  The film-forming recipe is as shown in Table 1. Regarding the film formation of each layer, the film-forming rate RATE (Å / SEC), the presence / absence of the introduction of oxygen gas, and the introduction amount of oxygen gas were changed. Two examples (test numbers 1-1 to 1-3) and two comparative examples (test numbers 1-4 and 1-5) were prepared and subjected to the following tests. The thickness TL of the uppermost layer was fixed at about 85 nm. IAD was not used for film formation. The heating temperature was 340 ° C., and the starting vacuum degree was 3.00E-03 Pa, respectively. 2 to 6 are diagrams illustrating the spectral characteristics of the multilayer films of the test numbers 1-1 to 1-5.

  As an evaluation item, the “photocatalytic effect measurement” was performed by irradiating the test sample with UV light for 5 minutes at a distance of 30 mm from YAZAWA's black light (model number BL20), and then “visualizer Pen” from inkintelligent. Was used to evaluate the color change stepwise. Here, a sample having a very small color change has no photocatalytic effect (evaluation ×), and a sample having a large color change has a photocatalytic effect (evaluation ○).

(Consideration of evaluation results)
With respect to the multilayer films of Test Nos. 1-1 to 1-3, when the thickness Tcat of the functional film was 300 to 582 nm, the evaluation of the photocatalytic effect measurement was ○ (see Table 8 described later). Also, as shown in FIGS. 2 to 4, each multilayer film realizes a good spectral characteristic as a visible region anti-reflection film when the reflectance is 1.5% or less mainly in the visible region (the allowable value is 2%). are doing.

  On the other hand, as shown in FIG. 5, the multilayer film of Test Nos. 1-4 achieves excellent spectral characteristics with a reflectance of 1% or less mainly in the visible region, but has a thickness Tcat of the functional film. Was 85 nm, the evaluation of the photocatalytic effect measurement was x. This can be attributed to the fact that the thickness of the functional film was too small to sufficiently exhibit the photocatalytic function.

  On the other hand, for the multilayer film of Test No. 1-5, when the film thickness Tcat of the functional film was 814 nm, the evaluation of the photocatalytic effect measurement was ○. However, as shown in FIG. It can be seen that the allowable value exceeded 2%, and a sufficient antireflection effect was not obtained. That is, it is understood that if the thickness Tcat of the functional film is too large, the spectral characteristics deteriorate.

  From the above results, it can be said that the functional film preferably has a thickness of at least 220 nm and not more than 700 nm in order to ensure a good balance between the photocatalytic effect and the spectral characteristics that tend to have a trade-off relationship.

(2) The present inventors formed a 15-layer or 7-layer multilayer film on a glass substrate having an optical power by a vapor deposition method while changing spectral characteristics, and submitted the test. More specifically, as shown in Table 3, a glass substrate TAF3 (manufactured by HOYA Co., Ltd .: refractive index 1.804) or M-BACD12 (manufactured by HOYA Co., Ltd .: refractive index 1.580) is coated with SiO 2 ₂ , a low refractive index layer using OA600, a high refractive index layer using OA600 (a material manufactured by Canon Optron Co., Ltd.), and a functional layer using TiO ₂ were laminated in the order shown in Table 3 to form a film. SiO ₂ was used as the uppermost layer. Table 3 shows the film forming recipe and film configuration of each layer.

  The film-forming recipe is as shown in Table 3. For the film-forming of each layer, the film-forming rate RATE (Å / SEC) and the amount of introduced oxygen gas were changed to obtain four examples (test number 2-1). To 2-4), and the photocatalytic effect and the spectral characteristics were evaluated. IAD was not used for film formation. Further, the thickness TL of the uppermost layer was 97 to 228 nm. The heating temperature was 340 ° C., and the starting vacuum degree was 3.00E-03 Pa, respectively. 7 to 10 are diagrams illustrating spectral characteristics of the multilayer films of the test numbers 2-1 to 2-4.

  Regarding the multilayer films of Test Nos. 2-1 to 2-4, when the thickness Tcat of the functional film was 244 to 427 nm, the evaluation of the photocatalytic effect measurement was ○ (see Table 8 described later). Further, as shown in FIG. 7, the multilayer film of Test No. 2-1 has a reflectance of 1% or less mainly in the near-infrared region (wavelength 700 nm to 1,050 nm), and exhibits good spectral characteristics as a near-infrared region antireflection film. Has been realized. As shown in FIG. 8, the multilayer film of Test No. 2-2 mainly has a reflectance of 1% or less in the near-infrared region (wavelength 1200 nm to 1800 nm) and realizes a good spectral characteristic as a near-infrared region antireflection film. ing. As shown in FIG. 9, the multilayer film of Test No. 2-3 mainly has a reflectance of 2% or less in the visible region (450 nm to 850 nm), and realizes a good spectral characteristic as a visible region antireflection film. The multilayer film of Test No. 2-4 has a reflectance of 1.5% or less mainly in the near-infrared region (wavelength 1200 nm to 1800 nm) as shown in FIG. Has been realized.

(3) The present inventors formed an eight-layered, ten-layered or 12-layered multilayer film on a glass base material having no optical power by a vapor deposition method while changing spectral characteristics, and submitted the test. More specifically, as shown in Table 4, on a glass substrate B270 (manufactured by SCHOTT: a refractive index of 1.52, also referred to as a white plate), a metal film, a low refractive index layer using SiO ₂ , OA600 ( A high refractive index layer using a material manufactured by Canon Optron Co., Ltd.) and a functional layer using TiO ₂ having a refractive index of 2.032 were stacked in the order shown in Table 4 to form a film. SiO ₂ was used as the uppermost layer. Table 4 shows the film forming recipe and film configuration of each layer.

  The film forming recipe is as shown in Table 4. Regarding the film forming of each layer, the film forming rate RATE (Å / SEC), the introduced amount of oxygen gas, and the material of the metal film were changed, and four examples (provided) were prepared. Test numbers 3-1 to 3-4) were prepared, and the photocatalytic effect and the spectral characteristics were respectively evaluated. The metal film of test number 3-1 is Al, the metal film of test number 3-2 is Cr, the metal film of test number 3-3 is Cu, and the metal film of test number 3-4 is Al. The film was Ni. IAD was not used for film formation. Further, the thickness TL of the uppermost layer was 77 to 89 nm. The heating temperature was 340 ° C., and the starting vacuum degree was 3.00E-03 Pa, respectively. 11 to 14 are diagrams illustrating the spectral characteristics of the multilayer films of the test numbers 3-1 to 3-4.

  Regarding the multilayer films of Test Nos. 3-1 to 3-4, when the thickness Tcat of the functional film was 300 to 351 nm, the evaluation of the photocatalytic effect measurement was ○ (see Table 8 described later). As shown in FIG. 11, the multilayer film of Test No. 3-1 has a reflectance of 75% or more mainly in the visible region to the near-infrared region (wavelength 400 nm to 1950 nm), and exhibits good spectral characteristics as a broadband reflection mirror. Has been realized. As shown in FIG. 12, the multilayer film of Test No. 3-2 mainly has a reflectance of 70% or more in the visible region (wavelength: 400 nm to 650 nm) and realizes a good spectral characteristic as a visible region reflection mirror. As shown in FIG. 13, the multilayer film of Test No. 3-3 has a reflectance of 85% or more mainly in the visible region to the near-infrared region, and realizes good spectral characteristics as a broadband reflection mirror. As shown in FIG. 14, the multilayer film of Test No. 3-4 has a reflectance of 75% or more mainly in the visible region (wavelength: 400 nm to 650 nm), and realizes good spectral characteristics as a visible region reflection mirror.

(4) The present inventors formed a 26- to 199-layered multilayer film on a glass substrate having no optical power by a vapor deposition method while changing spectral characteristics, and submitted the test. More specifically, as shown in Tables 5 to 7, a low-refractive-index layer using SiO ₂ on a glass substrate B270 (manufactured by SCHOTT: 1.52), and H4 (manufactured by MERCK: titanium) lanthanum (LaTiOx), TiO ₂ having a refractive index 2.401, TiO ₂ having a refractive index 2.431, or OA600 high refractive index layer using the (Canon Optron Ltd. materials), TiO refractive index 2.132 _The functional layers using No. ₂ were laminated and formed in the order shown in Table 5. SiO ₂ was used as the uppermost layer, and the film forming recipe and film configuration of each layer are shown in Tables 5 to 7.

  The deposition formulas are as shown in Tables 5 to 7. For the deposition of each layer, the deposition rate is set when the deposition rate RATE (Å / SEC), the introduced amount of oxygen gas, and the IAD are used. Four examples (test numbers 4-1 to 4-4) were prepared, and the photocatalytic effect and the spectral characteristics were evaluated. The thickness TL of the uppermost layer was set to 86 to 250 nm. The heating temperature was 340 ° C., and the starting vacuum degree was 3.00E-03 Pa, respectively. FIGS. 15 to 18 are diagrams showing the spectral characteristics of the multilayer films of the test numbers 4-1 to 4-4. In the test number 4-2, a dielectric multilayer film is used as a film for reflecting light.

  Note that “APC” stands for Auto Pressure Control and means that the partial pressure has been adjusted, and “SCCM” stands for standard cc / min, and is 1 atmosphere (atmospheric pressure 1013 hPa) and 0 ° C. for 1 minute. It is a unit that indicates how many cc flow around.

  Regarding the multilayer films of Test Nos. 4-1 to 4-4, when the film thickness Tcat of the functional film was 392 to 472 nm, the evaluation of the photocatalytic effect measurement was ○ (see Table 8 described later). As shown in FIG. 15, the multilayer film of Test No. 4-1 has a reflectance of around 50% mainly in the visible region (wavelength 360 nm to 700 nm), and realizes a good spectral characteristic as a visible region semi-transmissive film. ing. As shown in FIG. 16, the multilayer film of Test No. 4-2 mainly has a reflectance of 95% or more in the visible region (wavelength: 400 nm to 750 nm) and realizes a good spectral characteristic as a visible region reflection mirror. As shown in FIG. 17, the multilayer film of Test No. 4-3 mainly has a reflectance of 85% or more in an ultraviolet region (400 nm or less) and a reflectance of 2% or less in a visible region (wavelength 420 nm to 700 nm). In addition, excellent spectral characteristics are realized as a UV-IR cut filter having a wavelength selectivity of 95% or more in the near infrared region (800 nm to 1150 nm). As shown in FIG. 18, the multilayer film of Test No. 4-4 mainly has a reflectance of 95% or more in an ultraviolet region (400 nm or less) and a reflectance of 5% or less in a visible region (wavelength 400 nm to 750 nm). In addition, excellent spectral characteristics are realized as a UV-IR cut filter having a wavelength selectivity of 88% or more in the near infrared region (800 nm to 1950 nm).

(5) Summary The above study results are shown in Table 8 separately for Examples and Comparative Examples. here,
Tcat: film thickness (nm) of the functional layer adjacent to the uppermost layer
TL: film thickness of uppermost layer (nm)
NL: refractive index at d-line of material of low refractive index layer NH: refractive index at d-line of material of high refractive index layer Ns: refractive index at d-line of glass substrate.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an optical product that can obtain desired spectral characteristics while exhibiting a photocatalytic effect.

L Low refractive index layer H High refractive index layer M Metal layer GL Glass substrate MC Multilayer film

Claims (15)

In an optical product having a glass substrate on which three or more multilayer films are formed,
The multilayer film adjusts the spectral characteristics of the optical product by using at least one low-refractive-index layer and at least one high-refractive-index layer in combination.
The uppermost layer farthest from the glass substrate is the low refractive index layer,
The high refractive index layer adjacent to the uppermost layer is a functional layer mainly composed of a metal oxide having a photocatalytic function,
An optical product that satisfies the following condition:
60 nm ≦ TL ≦ 350 nm (1)
220 nm ≦ Tcat ≦ 700 nm (2)
here,
TL: film thickness of the uppermost layer Tcat: film thickness of the functional layer   The optical product according to claim 1, wherein the functional layer is formed from an oxide containing Ti as a main component. The optical product according to claim 1, wherein the uppermost layer is formed of SiO ₂ . The optical product according to claim 1, wherein the uppermost layer is formed from a mixture of SiO ₂ and Al ₂ O ₃ .   The optical product according to claim 1, wherein each layer of the multilayer film is formed by an evaporation method, and any one of the layers is formed by ion-assisted deposition.   The optical product according to claim 1, wherein the multilayer film has an antireflection property in a visible region.   The optical product according to claim 1, wherein the multilayer film has a semi-transmissive or high-reflective property in a visible region.   The optical product according to claim 1, wherein the multilayer film has an antireflection property in a near infrared region.   The optical product according to claim 1, wherein the multilayer film has a property of reflecting 70% or more of light in a near-infrared region.   The optical product according to any one of claims 1 to 9, wherein the multilayer film has a characteristic of reflecting 70% or more of ultraviolet light.   The optical product according to claim 1, wherein the multilayer film includes a metal film that reflects at least one of visible light and near-infrared light.   The optical product according to claim 11, wherein the metal film mainly includes one of Ag, Au, Cr, Al, Cu, and Ni. The optical product according to claim 1, wherein the following conditional expression is satisfied.
1.3 ≦ NL ≦ 1.5 (3)
1.9 ≦ NH ≦ 2.45 (4)
here,
NL: refractive index of the material of the low refractive index layer at d line NH: refractive index of the material of the high refractive index layer at d line The optical product according to any one of claims 1 to 13, wherein the glass substrate has an optical power and satisfies the following conditional expression.
1.7 ≦ Ns ≦ 2.2 (5)
here,
Ns: refractive index of the glass substrate at d-line The optical product according to any one of claims 1 to 13, wherein the glass substrate has no optical power and satisfies the following conditional expression.
1.45 ≦ Ns ≦ 1.65 (6)
here,
Ns: refractive index of the glass substrate at d-line