JP3454422B2 - Radio wave transmitting wavelength selective substrate and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of efficiently transmitting radio waves and visible light arriving at windows of buildings, automobiles, etc., and at the same time, reflects heat rays of the sun and exhibits sufficient heat insulating properties. The invention relates to a wavelength-selective substrate.

[0002]

2. Description of the Related Art In recent years, window glass coated with a conductive thin film or attached with a film containing a conductive thin film for the purpose of blocking solar radiation has become popular. When such a window glass is applied to a high-rise building, it reflects radio waves in the TV frequency band, causes a ghost on the TV screen, and makes it difficult to receive satellite broadcasts by the indoor antenna. Further, when it is used as a window glass for a house or a window glass for an automobile, it may be difficult for a mobile phone to communicate, or the gain of a glass antenna may be deteriorated.

Under these circumstances, at present, a glass substrate is coated with a transparent heat ray reflective film having a relatively high electric resistance,
It has been attempted to prevent radio wave interference by partially transmitting visible light and reducing reflection of radio waves.

In the case of glass with a conductive film, the length of the conductive film coated on the glass substrate is parallel to the electric field direction of the incident radio wave and is 1/20 times or less the wavelength of the radio wave. Japanese Patent No. 2620456 discloses that the antenna is divided into the following parts to prevent radio interference.

[0005]

However, the conventional method of coating a transparent heat ray reflective film having a relatively high electric resistance can reduce radio wave reflection and prevent radio wave interference, but has a heat ray shielding performance. Was not enough, and there was a problem in the comfort of life. Further, in the method of dividing the conductive film disclosed in Japanese Patent No. 2620456, since the length of division is much larger than the wavelengths of visible light and near-infrared light, which occupy most of the sunlight, these light beams are used. Are all reflected,
Although a radio wave transmitting wavelength selection screen glass that prevents radio wave interference and has sufficient solar radiation shielding performance can be obtained, there is a problem in that the transparency of visible light cannot be ensured. Furthermore, for a window with a large opening, such as 2m x 3m, for example,
To transmit satellite broadcast waves, the satellite broadcast wavelength should be about 2
1/20 of 5 mm, at least the conductive film must be cut into 1.25 mm square, preferably 0.5 mm square. Cutting a large-area conductive film into such small segments with, for example, an yttrium-aluminum-garnet laser requires a long time and is not realistic.

[0006]

First, the inventors of the present invention have disclosed in Japanese Patent Application No. 11-90597 that sputtering on a glass substrate surface or a glass substrate surface coated with an AlN layer (aluminum nitride layer). Ag consisting of continuous layers by the method
After forming the layer, heat treatment is performed to form granular Ag.
We filed an application for a radio wave transmitting wavelength selective glass in which an Ag layer that has been generated by changing the above is laminated. After various examinations,
The substrate is not limited to glass, and a heat-resistant transparent plastic substrate or a transparent ceramic substrate can be used to obtain a good radio wave transmitting wavelength selective substrate. Further, the granular Ag layer is not limited to the method of heat-treating after forming a continuous Ag layer. It has been found that a good radio wave transmitting wavelength selective substrate can be obtained even if a continuous Ag layer is formed on the surface of a heat-resistant plastic substrate or a transparent ceramic substrate that has been heated to produce a granular Ag layer. The present invention has been completed.

The present invention reduces the reflectance for radio waves in the respective frequency bands of TV broadcasting, satellite broadcasting and mobile phones to prevent radio wave interference, and has sufficient solar radiation shielding performance and visible light transmission. An object is to provide a radio wave transmitting wavelength selective substrate.

That is, the radio wave transmitting wavelength selective substrate of the present invention disperses granular Ag on the surface of a heat-resistant transparent plastic substrate or a transparent ceramic substrate or on the surface of the substrate coated with a transparent dielectric layer. It is characterized in that the Ag layers are laminated.

The Ag layer has an average particle size of 100 nm to 100 nm.
0.5 mm, the thickness of the particles is preferably composed of Ag particles in the range of 5 nm to 1 μm. Further, the granular Ag is preferably obtained by heat-treating Ag composed of a continuous layer, Granular Ag, which is a continuous layer of Ag that has been generated and changed, is the Ag before heat treatment.
It is preferable that the full width at half maximum of the Ag (111) plane identified by the X-ray diffraction method is reduced to 85% or less as compared with the above.

Furthermore, it is preferable that the light transmittance of the radio wave transmitting wavelength selective substrate has a maximum value in the wavelength range of 600 nm to 1500 nm.

Furthermore, a transparent dielectric layer may be coated on the Ag layer made of granular Ag.

Further, it is preferable that the shielding efficiency (Es) in the near infrared region defined by the formula (1) is 0.3 or more.

[0013]

[Formula 1]

Where λ is the wavelength of the electromagnetic wave incident on the substrate Rdp is the reflectance of the substrate in which granular Ag is dispersed Isr: the radiant intensity of the sun in the air mass 1.0, and the radio wave transmitting wavelength selective substrate of the present invention. The manufacturing method is as follows. After forming an Ag layer consisting of a continuous layer on the surface of a substrate made of a heat-resistant transparent plastic substrate or a transparent ceramic substrate, or on the surface of the substrate coated with a transparent dielectric layer,
It is characterized in that a heat treatment is performed to change and generate an Ag layer made of granular Ag.

Further, in the method for producing a radio wave transmitting wavelength selective substrate of the present invention, a transparent dielectric layer is coated on the surface of a heat-resistant transparent plastic substrate or transparent ceramic substrate which has been heated, or on the heat-resistant transparent plastic substrate or transparent ceramic substrate. A continuous layer of Ag is formed on the heated substrate surface.
It is characterized in that a layer is formed to change and generate an Ag layer made of granular Ag.

Further, an Ag layer made of a second continuous layer is further formed on the surface of the Ag layer made of a granular material, and then heat-treated to make the Ag layer made of the second continuous layer a granular Ag layer. It is also possible to change and generate.

Furthermore, a transparent dielectric layer can be further coated on the Ag layer made of granular Ag.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The radio wave permeable wavelength selective substrate of the present invention has a granular Ag content on the surface of a substrate made of a heat-resistant transparent plastic substrate or a transparent ceramic substrate, or on the surface of the substrate coated with a transparent dielectric layer. Ag dispersed
It is formed by coating layers.

As a typical method for forming a granular Ag layer, for example, the following two methods can be used.

In the first method, a continuous Ag layer made of Ag is formed on a surface of a heat-resistant transparent plastic substrate or a transparent ceramic substrate, or on a surface of the substrate coated with a transparent dielectric layer. After that, a heat treatment is performed to change the Ag in the Ag layer made of Ag of the continuous layer into granular Ag, which can be produced. The granular Ag obtained by such a method has the advantages that the particle size is large, the crystallinity is excellent, and the electrical conductivity inside the particle is high, and therefore, the characteristics such as high heat ray reflection characteristics can be expected. It is good and preferable.

In the second method, the heat-resistant transparent plastic substrate or the transparent ceramic substrate is heated on the surface, or the heat-resistant transparent plastic substrate or the transparent ceramic substrate is coated with the transparent dielectric layer on the heated surface. By forming an Ag layer made of a continuous layer, it is possible to immediately change and generate an Ag layer made of granular Ag. The granular Ag obtained by such a method is preferable because it has a uniform particle size and excellent characteristics such as excellent wavelength selectivity.

The heat-resistant transparent plastic substrate or the transparent ceramic substrate is heated, or the heat-resistant transparent plastic substrate or the transparent ceramic substrate is coated with the transparent dielectric layer on the heated surface, and the Ag layer is formed of a continuous layer. By immediately forming a film of Ag, it is converted into granular Ag, and A is formed on the surface of the second continuous layer.
It is also possible to change the Ag layer formed of the second continuous layer into a granular Ag layer by forming the g layer and heat-treating it. According to this method, the particle diameter of the granular Ag is uniform and It is particularly preferable because a large product can be obtained. The second
The substrate temperature at the time of forming the Ag layer formed of the continuous layer of
Although not particularly limited, it is preferably around room temperature for coarsening Ag particles.

The heat treatment temperature is 100 ° C. to 5 ° C.
It is preferable that the temperature is 00 ° C. and the holding time is about 5 minutes to 180 minutes,
It is not particularly limited to this range in order to obtain the target particle size.

The details of the mechanism by which the continuous Ag layer is converted into a granular Ag layer by the heat treatment are unknown. However, for example, a silver film deposited by sputtering has high surface energy. It is considered that when heat energy is applied, the particles are dispersed into particles and become a stable state with low surface energy.

The method for forming an Ag layer composed of continuous layers is as follows:
The sputtering method, the vacuum deposition method, the CVD method, the thermal spray method, the ion plating method and the like are not particularly limited, but the sputtering method is particularly preferable in terms of the uniformity of Ag particles to be produced and the productivity.

As the transparent substrate, it is possible to use a transparent heat-resistant plastic substrate or ceramic substrate which has excellent heat resistance and is chemically stable. The transparency is most preferably at the same level as glass, but is not particularly limited as long as it has a certain degree of transparency. Substrates satisfying these conditions include PTFE (tetrafluoroethylene resin), FEP (tetrafluoroethylene / hexafluoropropylene copolymer resin), P
FA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin) and the like can be mentioned, but especially FE
P and PFA are materials that satisfy all the conditions, and are more preferable.

Further, as the transparent dielectric film of the present invention, A
1N, Si ₃ N ₄ , transparent nitride film such as SiAlN, SiO
_x N _y, a transparent oxynitride film such as TiO _x N _y is preferred.
In addition, as the transparent oxynitride film, Cr, Z
A metal oxynitride composed of at least one metal element such as n, Zr, Sn and Ta can also be used. Also, S
Although a transparent metal oxide composed of at least one metal element such as i, Ti, Cr, Zn, Zr, Sn, and Ta can be used, in that case, before depositing the outermost transparent oxide film. In addition, it is necessary to deposit a metal sacrifice layer for preventing the oxidation of silver particles by several angstroms to several tens angstroms.

The obtained wavelength selection substrate reduces the reflectance for radio waves in the respective frequency bands of TV broadcasting, satellite broadcasting and mobile phones to prevent radio interference, and also has sufficient solar radiation shielding performance and visible light. It is a radio wave transmitting wavelength selection substrate having transparency.

The reflectance (Rdp) of the wavelength selection glass is
It can be calculated from the shape of silver by a theoretical formula as shown by the following formula (2). (This theoretical formula is calculated by the inventor of the Journal of Applied Phys.
ics Volume 84, Number 11,
6285-8290 (1998). )

[0030]

[Formula 2]

Here, Rdp: reflectance λ: wavelength [nm] AR: area ratio occupied by silver fine particles Rms: reflectance of silver multilayer film having silver layer thickness D: silver layer thickness [nm] Esg : Division coefficient (the ratio of the length of a square segment consisting of a plate glass substrate or a perfect conductor arranged infinitely and repeatedly on a dielectric film to the wavelength of incident light is Li / λ, and the area ratio occupied by the segment is AR reflection Li): Particle size [nm] Sr of fine silver particles Sr: Area ratio ni of fine silver particles having a particle size Li: The reflectance (Rdp) of the wavelength-selective glass of the present invention is equal to or smaller than the number of fine silver particles having a particle size Li.
The fact that the shape of silver can be calculated by the theoretical formula represented by the above formula (2) is represented by the following formulas (3) to (1).
4) will be described.

A method for deriving an electrical integral equation for calculating the reflectance of a system in which perfect conductor segments are periodically fixed on a dielectric substrate will be described below step by step. First, how to obtain the division coefficient Esg by the theoretical formula will be described.

(1) Induced Current Distribution In the following calculation, it is assumed that radiation from the conductor segment and the dielectric substrate induces an electromagnetic field. The periodic array and electromagnetic wave states discussed here are shown geometrically in FIG. x
An infinite period array of each of the axis units a and b of the axis and the y axis is fixed on the dielectric substrate. Substrate thickness is d, dielectric constant is ε
r. Electric field strength Ei propagating from (θi, φi) direction
Suppose we illuminate a frequency selective screen with an incident plane wave of. α is the polarization angle in the (θi, φi) plane.

[0034]

[Formula 3]

Here, r is a position vector, and ki is a propagation vector of an incident wave (a wave number vector indicating a propagation constant in the traveling direction of an electromagnetic wave).

It is assumed that the current J c is induced on the conductor surface by the incident wave. This current is proportional to the phase of the incident wave. And since the structure is periodic, the current can be Fourier series expanded. Therefore, the current distribution can be expressed as follows.

[0037]

[Formula 4]

[0038]

[Formula 5]

In order to handle the electromagnetic field generated by the scattered wave from the conductor and the electromagnetic field generated by the scattered wave from the dielectric surface with a single electromagnetic field, it is equivalent to the equivalent current Ji induced on the dielectric substrate surface. The magnetic current M i is defined as follows.

[0040]

[Formula 6]

A conductor of arbitrary shape can be electrically approximated by a wire segment. The current distribution is a piecewise sine wave (PW
S) It can be expressed by a function.

[0042]

[Formula 7]

[0043]

[Formula 8]

(2) Radiation field (reflected electric field and reflected magnetic field) The electric field emitted by the induced magnetic current / induced current on the surface of the scatterer is called the reflected electric field. This reflected electric field can be expressed by Equation (9) using the Green's function.

[0045]

[Formula 9]

(3) Power reflectance

[0047]

[Formula 10]

[0048]

[Formula 11]

[0049]

[Formula 12]

The method for obtaining the division coefficient Esg has been described above.

Next, the particle size distribution (particle size of silver particles, area ratio, number of particles) of the equation (2) is obtained. (4) Average particle size of silver particles

[0052]

[Formula 13]

The average particle size (l) of silver particles can be calculated as follows.

[0054]

[Formula 14]

As described in Reference Example 2 to be described later, in order to secure the shielding efficiency in the near infrared region of 0.3 or more, the average particle diameter of silver particles is 100 nm or more and the thickness of silver particles is 5 nm.
The above is preferable. The particle size of the silver particles is 0.
If it is 5 mm or more, there is a problem of radio interference, which is not preferable.

Next, a method of obtaining the reflectance from the above-mentioned division coefficient Esg and particle size distribution will be described. (5) Theoretical formula of the reflectance of an AlN system in which silver is dispersed The reflectance of the Ag layer is affected by the plasma vibration of silver atoms. Therefore, the reflectance (Rdp) of the AlN layer in which silver is dispersed
Depends on the surface resistivity (Rsq), the wavelength of the incident wave (λ) and the grain size of silver. The effect of particle size on Rdp is calculated by dividing factor (E
It is expressed in terms of sg).

The theoretical value of the reflectance of a system in which square segments of a perfect conductor are periodically fixed on an AlN layer having a thickness of 40 nm is defined as Esg. The theoretical value is calculated using equation (12). This coefficient depends on L / λ and the area ratio (AR). L / λ is the ratio of the segment size (corresponding to the particle size of silver particles) to the wavelength of the incident light shown in FIG.
Incidentally, FIG. 2 is a diagram showing the ratio of the wavelength of the AR = 2 ^{2/3 2} of division factor (Esg) and L / lambda (segment size and the incident light.

AR is L / a, that is, the ratio of the area of the segment to the area of the unit cell (minimum repeating unit) shown in FIG. Despite AR = 2/3 (= 0.444), Esg in FIG. 2 is L / λ = 0.525 and approaches 1.0. This is because when the Rsq. Of the conductor and the dielectric loss factor of the substrate are so small that they can be ignored, the energy of the incident wave is completely converted into the induced current on the unit cell at the resonance frequency. Assuming that Rdp is equal to the product of Rms and Esg, the formula (2) for obtaining Rdp is proposed. Rms is AlN
It is the reflectance of (30 nm) / Ag (Dnm) / AlN (10 nm) multilayer film. In addition, D is an average thickness of Ag particles.

[0059]

[Formula 2]

Here,

[0061]

[Formula 15]

Here, A Ro is the ratio of silver particles to the total area of the thin film.

Rms is a function of Rsq and λ. And E
Since sq depends on L / λ, in the equation (2), Rdp is Rsq,
It shows that it depends on λ and L. The Σ term describes the effect of the particle size distribution of silver particles on Rdp. As shown in FIG. 2, since the change of Esq with the increase of L / λ is non-linear, the term Σ is necessary. The total weight of Ag in the AlN layer is kept constant during the heat treatment of the Ag layer, so that D and L
Can be expressed by equations (2) and (15).

[0064]

[Formula 16]

[0065]

[Formula 17]

Where Lm is the average length of the segment,
D0 is the thickness of the Ag layer in the multilayer film immediately after film formation.

In addition, since Ag has a plasma frequency in the ultraviolet region, and there is a region called "silver window" in which the extinction coefficient of Ag is infinitely small on the low frequency side of this frequency, Ag By controlling the thickness of the particles and the thickness of the dielectric interference film, the visible light transmittance can be secured. Ag by heating
The film changes to a state of being dispersed in the form of particles. This particle size is
Glass that is far smaller than 0.5 mm and that selectively reflects near infrared rays can be obtained by controlling the thickness of the Ag film, the heat treatment conditions, and the like.

Hereinafter, examples of the specification filed by the inventors of the present invention will be shown as reference examples.

[0069]

Reference Example Reference Example 1 The radio wave transmitting wavelength selective glass was formed by a DC magnetron sputtering method. The vacuum chamber was evacuated to 2 × 10 ⁻⁴ Pa before sputtering. The distance between the target and the glass substrate was fixed at 90 mm during sputtering. The bottom AlN layer is a pure Al target (diameter 129
mm, thickness 10 mm). In order to prevent abnormal discharge, frequency 10k
A rectangular pulse wave of Hz was applied to the cathode. During the sputtering, the pressure of the mixed gas was controlled to 0.7 Pa by the method of adjusting the N ₂ / Ar gas flow rate ratio to 20/80. With a gas pressure of argon of 0.7 Pa and using a pure Ag target (diameter 129 mm, thickness 5 mm), A of the intermediate layer
A g-layer was deposited. Before stacking the uppermost AlN layer, the AlN / Ag layer immediately after the film formation was formed into 2 × 10 ⁻⁴ P in a sputtering vacuum chamber.
a, heat treatment was performed at 200 ° C. The uppermost AlN layer is a pure Al target (diameter 129 mm, thickness 10 m) by the same method as the lowermost AlN layer.
m) was used to deposit by reactive sputtering.

With respect to the sample consisting of the glass substrate / AlN layer / Ag layer after the above steps or steps, the particle size distribution of silver particles was measured by the following method.

A. The surface condition of the sample consisting of the glass substrate / AlN layer / Ag layer after the step of grain size distribution of silver particles was observed with a scanning electron microscope (SEM) using Hitachi S-415. The results are shown in Fig. 3. The particle size distribution obtained by reading the size of each particle in FIG. 3 by the Martin method is shown in Table 1.

As a result, the area ratio (defined as the ratio of the area occupied by silver particles to the total area) was 0.20. Particle size in Table 1 (l)
Substituting the number (n) and equation (13) into equations (13) and (14), the average particle diameter was 87 nm. The particle size distribution is shown in Table 2 as a function of Sr. Glass substrate / Al which finished the process of
The state of the surface of the sample composed of N layer / Ag layer was observed by an atomic force microscope (AFM) using SPA-250 manufactured by Seiko, and as a result, the average particle size was 168 nm and the area ratio was 0.38. It was

[0073]

[Table 1]

[0074]

[Table 2]

B. Crystal Orientation The orientation of silver crystals was evaluated with respect to the sample consisting of the glass substrate / AlN layer / Ag layer which has undergone the above steps and. In addition, the measurement was performed by an X-ray diffraction (XRD) method of RINT-1500 manufactured by Rigaku using a characteristic X-ray of CuKα.

As a result, it is shown that the Ag layer in the sample of the glass substrate / AlN layer / Ag layer immediately after the film formation after the above step includes the polycrystalline silver in which the Ag (111) plane is grown parallel to the substrate. There is. When the Ag continuous layer was changed into discontinuous particles as shown in FIG. 3 by carrying out the heat treatment of the step, the intensity of the diffraction peak on the Ag (200) plane increased to some extent. Table 3 shows Ag (111)
As a result of heat treatment with a surface spacing of 2 hours, 236.6 to 2
It is shown to decrease to 35.9 pm. The full width at half maximum of the peak also tended to decrease.

[0077]

[Table 3]

C. The reflectance spectra of the sample immediately after film formation in which the reflectance step was completed and the heat-treated sample in which the step was completed were measured. In addition,
FIG. 4 shows the result of measurement of the reflection spectrum in the range of 350 to 1800 nm at room temperature using a Hitachi 340 spectrophotometer.

The thickness of the Ag layer is obtained from the reflectance curve of the sample immediately after the film formation, which has been completed. The theoretical curve of reflectance calculated by the 4-terminal matrix method was in good agreement with the measured value when the thickness of the Ag layer immediately after film formation was 8 nm, as shown in FIG. Note that FIG. 5 is a diagram showing a comparison of the reflection spectrum between the experimental value (◯) and the theoretical value (−) of the sample immediately after the film formation. The theoretical value was calculated assuming that the thickness of the Ag layer is 8 nm.

On the other hand, in Table 3, Ag having a heating time of 0 hours is
The full width at half maximum of the (111) peak is calculated by the equation (18) [Scherr
er]] and the thickness of the crystal in the Ag layer immediately after film formation was determined, and the value was 10 nm. The thickness of the Ag layer will be equal to the size of the crystal. That is, A
It is shown that the g layer is composed of polycrystalline silver in which the Ag (111) plane parallel to the substrate is grown.

[0081]

[Formula 18]

Here, CT: thickness of crystal [Å] λ: wavelength of irradiated X-ray [Å] Δ (2θ): full width at half maximum [radian] θ: incident angle of X-ray [radian] The reflectance curve of the heat-treated sample which completed the process showed that the heat treatment of the Ag layer increased the reflectance of the incident wave whose wavelength was shorter than 780 nm and decreased the reflectance of the incident wave whose wavelength was longer than 780 nm. This phenomenon is
It is considered that this is due to the dispersion of silver particles having a particle size smaller than the wavelength of the incident wave.

The curve shown in FIG. 6 indicates that the area average particle diameter of silver fine particles is 130 nm, the thickness of silver particles is 18 nm, and the area ratio is 0.4.
Regarding the reflectance of the wavelength selection film of No. 44, 350 nm to 180
It is a theoretical curve obtained from theoretical formula (2) in the wavelength range of 0 nm. This curve is in good agreement with the value of the example shown by the black circle in FIG. However, as shown in Table 4, S
The average particle diameter observed by EM is smaller than the theoretical particle diameter. This difference is due to the underestimation of the grain size of silver in SEM observation. That is, it is considered that the intensity of the secondary electrons scattered from the skirt of the particle having a thickness of about 3 nm is weak, and therefore it cannot be detected as the skirt of the particle. Also,
As shown in Table 4, the thickness of the silver particles of the silver particles of the silver particles is in agreement with the measured value obtained by X-ray. In this reference example, the validity of the theoretical formula (2) was proved.

[0084]

[Table 4]

Reference Example 2 Since the validity of the theoretical formula (2) could be proved in Reference Example 1,
The shape of the silver fine particles suitable for the wavelength selection film is obtained from the theoretical value of the equation (2). First, the blocking efficiency (Es) of the silver particle system is defined by the equation (1). Assuming that Sr in equation (2) is constant for various average sizes (Li) of the segments, the maximum shielding efficiency of the silver particle system with AR = 0.444 and D0 = 8 nm is given by equation (2). calculate. As shown in FIG.
= 375 nm, the shielding efficiency is maximized while ensuring the transparency of the insulating glass in the visible light and broadcast wave regions.
FIG. 7 is a diagram showing the blocking efficiency of the silver particle system and the average size of the segments. Saegihei ^{efficiency, AR = 2 2/3 2} ,
It was calculated from the equation (2) assuming that Li = 18 nm. Li =
The theoretical curve of the reflection spectrum at 375 nm is shown in FIG. It is a figure which shows the comparison of the theoretical reflection spectrum (-) of 375 nm and the measured reflection spectrum (-) of Lm = 130 nm in a silver particle dispersed AlN film. Theoretical value ^{AR = 2 2/3 2,} Li = 18
It was calculated from the equation (2) assuming nm.

As Lm = Li increases from 130 nm to 375 nm, the position where the maximum reflection occurs shifts to the long wavelength side. This indicates that a wavelength selection screen that reflects only near infrared rays can be designed by adjusting the size of silver particles. The theoretical value of reflectance is 800
It sharply decreases at 5 to 6 points in the wavelength range of nm or less. Since the segments are arranged periodically, in the case of FIG.
The reflectance sharply decreases at /λ=0.626.

Next, as a typical example, the theoretical formula (2) is used to determine the shielding efficiency in the near infrared region of the wavelength-selective glass and the thickness dependence of the visible light transmittance of the silver fine particles when the area average particle diameter of the silver fine particles is 375 nm. Results are shown in Tables 5 and 6. The area ratios used were 0.444 and 0.826 as typical values.

From Tables 5 and 6, in order to secure the shielding efficiency in the near infrared region of 0.3 or more, the thickness of the silver fine particles should be 5 n.
It turns out that m or more is necessary. On the other hand, when the thickness of the silver particles exceeds 30 nm, the shielding efficiency in the near infrared region reaches saturation while having a visible light transmittance.

Since the thickness of silver particles obtained from Scherrer's equation of equation (18) is inversely proportional to the half-value width of the diffraction peak of the (111) plane of Ag, the measurement limit of the grain thickness is the half-value width. Determined by the detection limit value. This value is the current X
In the line diffraction device, it is about 0.01 degree. Substituting this value into equation (18) yields 1 μm. That is, Sc
The Herrrer equation is applicable only when the thickness of the silver particles is 1 μm or less. Therefore, the preferable thickness of the silver fine particles is in the range of 5 nm to 1 μm. The wavelength of the characteristic X-ray of CuKα is 1.5405Å, and the incident angle of the X-ray corresponding to the (111) plane of Ag is 38.12 / 2 degrees.

[0090]

[Table 5]

[0091]

[Table 6]

As a typical example, the thickness of silver fine particles is 20 nm.
Table 7 and Table 8 show the results obtained by theoretical formula (2) for the shielding effect in the near-infrared region of the wavelength-selective glass and the area average particle size dependency of the silver particles in the case of the above. From Table 7 and Table 8, it can be seen that the particle size of the silver fine particles needs to be 100 nm or more in order to secure the shielding effect in the near infrared region of 0.3 or more. The shielding effect increases as the particle size increases, but it decreases when the particle size exceeds a certain value, depending on the area ratio. However, the shielding efficiency does not fall below 0.3. However, if the particle size becomes 1/20 or more of the wavelength of the shortest satellite broadcast wave among currently used broadcast waves, radio wave interference becomes a problem (see Patent Registration No. 2620456). The particle size is preferably 0.5 mm or less.

[0093]

[Table 7]

[0094]

[Table 8]

[0095]

EXAMPLE An example of implementing the present invention will be described below. However,
The present invention is not limited to this.

Example 1 A radio wave transmitting wavelength selective substrate was formed by a magnetron sputtering method. For the transparent substrate, 1 mm thick PFA resin (tetrafluoroethylene-perfluoroalkoxy copolymer) having excellent heat resistance was used. The PFA resin has the same transparency as glass and is a chemically stable substance. The vacuum chamber was evacuated to 2 × 10 ⁻⁴ Pa before sputtering. The distance between the target and the substrate was fixed at 90 mm during sputtering. The bottom AlN layer is an Al target (diameter: 76 m).
m, 5 mm thick) was deposited by DC reactive sputtering. N2 gas is used as the reactive gas, and the pressure is adjusted to 1.0 P by adjusting the N2 gas flow rate during sputtering.
Controlled to a. Heat the glass substrate / AlN layer in a vacuum chamber to 250 ° C.
Held in. Using a pure Ag target (diameter: 76 mm, thickness: 5 mm) with an argon gas pressure of 1.0 Pa, a continuous layer of Ag was deposited on a glass substrate kept at 250 ° C., and immediately thereafter, the continuous layer was changed to granular Ag. Was generated. The uppermost AlN layer is an Al target (diameter 76 mm, thickness 5 mm) in the same manner as the lowermost AlN layer.
Was used for DC reactive sputtering.

With respect to the sample composed of the PFA substrate / AlN layer / Ag / AlN layer which has undergone the above steps, the radio wave transmittance, the average particle diameter of silver particles, the average thickness and the reflectance were measured by the following methods. It was A. Radio wave permeability PFA substrate / AlN layer / Ag /
The surface resistivity (Ω / sq) of the AlN layer sample is
As a result of measuring with a surface resistance measuring device (MEGARESTAH0709) manufactured by Shishido Electric Co., it is 9.9 × 10 ¹² Ω / sq or more, and the radio wave transmission is sufficiently satisfied. B. Particle size distribution of silver particles PFA substrate / AlN layer / Ag /
The state of the surface of the sample composed of the AlN layer was measured using a field emission scanning electron microscope (F
E-SEM) and the image was analyzed using image analysis software Image-Pro PLUS manufactured by Cybemetics. As a result, the average particle diameter was 330 nm and the granular Ag having an area ratio of 0.7 was dispersed. It was possible to confirm the Ag layer. C. Average thickness of silver particles PFA substrate / AlN layer / Ag /
The orientation of the silver crystal of the sample consisting of the AlN layer was changed to CuK
It was measured by the X-ray diffraction (XRD) method of Rigaku RINT-1500 using characteristic X-rays of α. Ag based on the result
The full width at half maximum of the (111) peak is calculated by the equation (18) [Scherr
er]] and the thickness of the crystal in the Ag layer immediately after film formation was determined, and the value was 25 nm.

[0098]

[Formula 18]

Here, CT: thickness of crystal [Å] λ: wavelength of irradiated X-ray [Å] Δ (2θ): half width [radian] θ: incident angle of X-ray [radian] D. reflectance The reflection spectrum of the sample which completed the process was measured in the range of 340 nm to 1800 nm using the Hitachi U-4000 type self-recording spectrophotometer. As a result, by depositing Ag on the heated substrate and atomizing it, as shown in FIG. 9, the reflectance at a wavelength of 900 nm is 82.
%, Which was a very high value.

[0100]

INDUSTRIAL APPLICABILITY The present invention reduces reflectance for radio waves in the respective frequency bands of TV broadcasting, satellite broadcasting, and mobile phones, and has sufficient solar shading performance and visible light transmittance, so that it can be displayed on a TV screen. It is possible to have a comfortable life such as no radio interference such as generation of a ghost, a loss of access to a mobile phone, and a poor gain of a glass antenna, and sufficient shielding of solar radiation.

[Brief description of drawings]

FIG. 1 shows a geometrical drawing of a scatterer.

[Figure 2] AR = ² 2/3 2 of the division factor (Esg) and L / λ
It is a figure which shows the relationship between the size of a segment and the wavelength ratio of incident light.

FIG. 3 is a view showing an SEM micrograph of a silver-dispersed AlN layer.

FIG. 4 is a diagram showing reflectance before and after heat treatment.

FIG. 5 is a diagram showing a comparison between an experiment (◯) and a theoretical (−) reflection spectrum of a sample immediately after film formation.

FIG. 6 is a diagram showing a comparison between an experimental value (●) and a theoretical value (−) of a reflection spectrum of a silver-dispersed AlN film.

FIG. 7 is a diagram showing the relationship between the shielding effect of a silver particle system and the average size of a segment.

FIG. 8 is a diagram showing a comparison between a theoretical reflection spectrum (−) at Lm = 375 nm and a measured reflection spectrum (●) at Lm = 130 nm in a silver particle-dispersed AlN film.

FIG. 9 is a reflection characteristic diagram of the radio wave transmitting wavelength selective glass in Example 1.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-325034 (JP, A) JP-A-63-230334 (JP, A) JP-A-1-206035 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 C23C 14/00-14/58

Claims (11)

(57) [Claims] 1. An Ag layer in which granular Ag is dispersed is laminated on a surface of a heat-resistant transparent plastic substrate or a transparent ceramic substrate, or on a surface of the substrate coated with a transparent dielectric layer. Characteristic radio wave transparent wavelength selection substrate. 2. The Ag layer has an average particle size of 100 nm to 0.5 m.
2. The radio wave transmitting wavelength selective substrate according to claim 1, wherein the wavelength transmitting substrate is made of Ag particles having a particle size of m and a particle thickness of 5 nm to 1 μm. 3. The radio wave transmitting wavelength selective substrate according to claim 1, wherein the granular Ag is obtained by heat treating Ag composed of a continuous layer. 4. The granular Ag having a continuous layer formed by changing the generation of Ag has a half-value width of 85% of the Ag (111) plane identified by X-ray diffraction as compared with Ag of the continuous layer before heat treatment. The radio wave transmitting wavelength selection substrate according to claim 3, wherein the number is reduced to the following. 5. The radio wave transmissive wavelength selection substrate according to claim 1, wherein the light ray reflectivity of the radio wave transmissive wavelength selection substrate has a maximum value in a wavelength range of 600 nm to 1500 nm. 6. A dielectric layer is further coated on an Ag layer made of granular Ag, and the dielectric layer is further covered.
The radio wave transmitting wavelength selection substrate described. 7. The shielding efficiency (Es) in the near infrared region defined by the formula (1) is 0.3 or more.
To 6 radio wave transmitting wavelength selection substrates. [Formula 1] Where λ: wavelength of electromagnetic wave incident on the substrate Rdp: reflectance of the substrate on which granular Ag is dispersed Isr: radiant intensity of the sun at air mass 1.0 8. A Ag layer made of a continuous layer is formed on the surface of a substrate made of a heat-resistant transparent plastic substrate or a transparent ceramic substrate, or on the surface of the substrate coated with a transparent dielectric layer, and then heat-treated. A method of manufacturing a radio wave transmitting wavelength selective substrate, characterized in that an Ag layer made of granular Ag is generated and changed. 9. A continuous layer of Ag on a surface of a heat-resistant transparent plastic substrate or a transparent ceramic substrate which is heated, or on a surface of a substrate obtained by coating a transparent dielectric layer on a heat-resistant transparent plastic substrate or a transparent ceramic substrate.
A method of manufacturing a radio wave transmission wavelength selective substrate, characterized in that an Ag layer made of granular Ag is generated by forming a layer. 10. An Ag layer made of a second continuous layer is further formed on the surface of the Ag layer made of a granular material, and then the Ag layer made of the second continuous layer is heat-treated to form a granular Ag layer.
The method for producing a radio wave transmitting wavelength selective substrate according to claim 9, wherein the layer is changed and generated. 11. A transparent dielectric layer is further coated on an Ag layer made of granular Ag.
11. A method of manufacturing a radio wave transmitting wavelength selection substrate according to any one of claims 1 to 10.