JPH03208253A - Light interference membrane and tube bulb using same - Google Patents

Abstract

PURPOSE:To improve the refractive index, the transmission factor, and the mechanical strength, by making the crystal particle diameter and the porosity in the membranous thickness direction of titanium oxide, in a light interference membrane which is formed of a membrane including crystals of an anatase or a rutile of titanium oxide, or both of them, less than a specific value. CONSTITUTION:A visible light transmitting infrared-ray reflecting membrane 8 to be a light interference membrane is composed as a dielectric multilayer membrane by laminating a high refractive index layer 81 which consists of TiO2, and a low refractive index layer 82 which consists of SiO2. The TiO2 in the layer 81 is made into a crystalline formation of anatases or rutiles, or mixing both crystals, and the crystal particle diameter of the TiO2 is regulated to be less than 1400Angstrom , and the porosity of the TiO2 layer in the membranous thickness direction is regulated to be less than 30%. As a result, clearances between the crystal particles are reduced, the refractive index and the transmission factor are increased, and the contact areas of crystal particles each other are increased so as to improve the mechanical strength.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention provides an optical interference film with a high refractive index layer made of anatase or rutile of titanium oxide, or a crystal system of both of these, and an optical interference film using the same. Regarding tubes.

(Prior Art) For example, a halogen light bulb is constructed by housing a filament in a bulb made of quartz glass and sealing halogen gas inside the bulb.

Recently, in order to improve the lamp efficiency of this type of halogen bulb, titanium oxide (T
iO2) and silicon oxide (SrO2)
A lamp in which an optical interference film made of a dielectric multilayer film is formed has been proposed.

Such a light interference film acts, for example, as a visible light transmitting infrared reflective film and transmits the visible light emitted from the filament, but the infrared rays are reflected by this light interference film, that is, this infrared reflective film, and the reflected Infrared radiation is directed back into the filament, allowing it to be reheated and increase lamp efficiency by as much as 15-35%.

The optical interference film that functions as the visible light transmitting infrared reflecting film is configured as a multilayer film of, for example, a total of 9 to 12 layers, in which metal oxides with a high refractive index and metal oxides with a low refractive index are alternately layered. As the metal oxide with a high refractive index, titanium oxide (T i O2), which has excellent optical properties such as transmittance and refractive index and has excellent heat resistance, is used, and metal oxides with a low refractive index are used. Silicon oxide (5102), which has excellent optical properties and heat resistance, is used as a material.

On the other hand, by selecting a combination of a metal oxide with a high refractive index and a metal oxide with a low refractive index, the optical interference film described above has the ability to not only reflect the infrared rays described above but also reflect unnecessary light. It can also be used as an optical interference filter that selectively transmits only necessary light.

Further improvements in optical properties are required for such infrared reflective films and photoselective photosensitive films. It is known that in order to improve optical properties, it is sufficient to increase the refractive index difference between a high refractive index layer and a low refractive index layer. It is desired to increase the refractive index and transmittance of a titanium oxide (T i0 2 ) film that functions as a film at a desired wavelength.

The conventional high refractive index layer made of titanium oxide (T 1 0 2 ) had a non-quality main component and had a crystal system in which anatase crystals of titanium oxide were partially mixed.

However, such a high refractive index layer has a problem in that it cannot be expected to significantly improve the refractive index and transmittance.

Therefore, as a result of repeated research and various studies and experiments, the present inventors made the high refractive index layer by using titanium oxide (T i O
2) Heat resistance can be obtained by forming a thin film having crystal systems of anatase, rutile, or both, and refractive index and transmittance can be improved without deteriorating releasability even when multilayered. I found a headline.

(Problems to be Solved by the Invention) However, thin films made of titanium oxide in the anatase, rutile, or both crystal systems tend to have a crystal grain structure, and the film is formed by aggregation of crystal grains. Microscopically, gaps tend to form between crystal grains, and these gaps can diffuse light and reduce the transmittance of visible light, and the contact area between crystal grains becomes smaller, making them easier to peel off. In some cases, multi-layering may not be possible.

The present invention aims to provide an optical interference film that has high refractive index and transmittance and improved mechanical strength (non-peelability), and a tube using the same.

[Structure of the Invention] (Means for Solving the Problems) The first aspect of the present invention is a thin film formed on the surface of a substrate that transmits or reflects light and having a crystal system of anatase or rutile of titanium oxide or both of these. In the optical interference film obtained, the crystal grain size of the titanium oxide was set to 1400.
The porosity in the film thickness direction is 30% or less.

The second aspect of the present invention is formed by alternately layering a high refractive index metal oxide and a low refractive index metal oxide on the surface of a substrate that transmits or reflects light, and the high refractive index metal oxide In an optical interference film in which the layer is formed of a thin film having a crystal system of titanium oxide anatase or rutile or both, the high refractive index layer made of titanium oxide has a crystal grain size of 1400λ or less and 30% porosity
It is characterized by the following.

The third aspect of the present invention is a light-transmitting bulb having an optical interference film formed of a thin film having an anatase or rutile crystal system of titanium oxide or both on the surface of the light-transmitting bulb. is 1400λ or less, and the porosity in the film thickness direction is 30% or less.

Furthermore, the fourth aspect of the present invention is to form an optical interference film by alternately layering a metal oxide with a high refractive index and a metal oxide with a low refractive index on the surface of a light-transmitting bulb. In a tube where the oxide layer is formed of a thin film having a crystal system of titanium oxide anatase or rutile, or both of these,
The high refractive index layer made of titanium oxide has a crystal grain size of 14
00λ or less, and the porosity in the film thickness direction is 30% or less.

(Function) In each of the above inventions, the refractive index and transmittance can be improved because the thin film of titanium oxide is made of rutile or anatase or both crystal systems, and in particular, the crystal grain size of titanium oxide can be reduced to 1400 J or less. At the same time, since the porosity in the film thickness direction was reduced to 30% or less, the transmittance improved,
Moreover, the binding force of the film is increased and peeling is prevented.

(Example) The present invention will be described below based on an example shown in FIGS. 1 to 4.

The figure shows a halogen light bulb for studio use, and numeral 1 is a bulb made of transparent quartz glass, which is in the shape of a straight tube.

Crush sealing parts 2, 2 are formed at both ends of the bulb 1, and metal foil conductors 3, 3 made of molybdenum or the like are sealed to these sealing parts 2, 2. Internal lead-in wires 4, 4 are connected to these metal foil conductors 3, 3, and a filament 5 made of tungsten or the like is installed between these internal lead-in wires 4, 4. The filament 5 has a plurality of anchors 6. 、． is held so as to be positioned on the axis of the valve 1.

External lead-in wires 7, 7 are connected to the metal foil conductors 3, 3, and these external lead-in wires 7, 7 are connected to a power source.

The valve 1 is filled with, for example, Krybton gas and halogen at a predetermined pressure.

An optical interference film is formed on the outer surface of such a bulb 1. The optical interference film of this embodiment is a visible light transmitting infrared reflective film 8, and this visible light transmitting infrared reflective film 8 has high refractive index layers 81 and low refractive index layers 82 alternately, as shown in FIG. The dielectric multilayer film is composed of, for example, 9 to 12 layers in total.

The high refractive index layer 81 is formed of titanium oxide (T f 02 ), and the low refractive index layer 82 is formed of silicon oxide (Si02).

The titanium oxide of the high refractive index layer 81 has a crystalline form of anatase or rutile, or a mixture of both, and the A grain size of this titanium oxide is 100 to 140.
0λ, and the average particle size is 500 to 1000λ.

Since the high refractive index layer 81 of titanium oxide is formed by an aggregate of crystal grains, gaps are generated between each crystal grain, and when this gap becomes large, light is diffused and the transmittance decreases. Moreover, since the contact area between crystal grains becomes smaller, there is a concern that peeling may easily occur. To prevent this, the porosity ρ of the titanium oxide layer when viewed in the cross section in the film thickness direction is set to 3.
It is regulated to be 0% or less.

If we define the porosity ρ here, the porosity ρ is the cross-sectional area B occupied by the titanium oxide layer in a cross section of the titanium oxide layer cut in the film thickness direction at an arbitrary part, and the voids generated in the titanium oxide layer. (Including voids between the substrate and the titanium oxide layer)
It refers to the ratio of the cross-sectional area A to (A/(A+B)).

In order to lower the porosity ρ in this way, the size and shape of the crystal grains of titanium oxide are involved. Or it is preferably a polygon close to a sphere. In this case, since the space is filled, the light transmittance is improved, and the contact area between the crystal grains is increased, making it difficult to peel off.

Such a visible light transmitting infrared reflecting film 8 can be made by the following method.

That is, the coating method for the infrared reflective film 8 usually includes vacuum evaporation, CVD, sputtering, organometallic immersion firing, and the like. Among these, organometallic immersion-fired bulbs are formed by immersing the bulb in an organometallic compound solution, pulling it up at a constant speed, drying it, and baking it, so it can be easily formed with fewer steps.

A specific example using this organometallic immersion and firing method will be described below.

As the organometallic solution, for example, a composition in the form of a titanium oxide thin film is used, which is composed of an organic solvent solution containing a reaction product of titanium alkoxide and glycol. More specifically, the titanium alkoxide is a monomer such as tetramethoxytitanium, tetraethoxytitanium, or tetraisoproboxytitanium, or a polymer obtained by partially hydrolyzing and polycondensing these monomers, or a combination of these monomers and a polymer. Mixtures are used and the glycols used are, for example, alkylene glycols such as diethylene glycol.

Then, Fukai, which is a mixture of acetic acid ester and a titanium compound mainly composed of tetraisopropyl titanate with a titanium content of 2 to 3%, was prepared with a viscosity of about 1.5%. Adjust to Ocps and place in a predetermined constant temperature and humidity atmosphere.

Add valve 1, which has been previously cleaned with ethyl alcohol, to this solution.
The titanium compound Fukai is immersed in the valve 1, and the titanium compound Fukai is deposited on the outer surface of the bulb 1 by being pulled up from the Fukai at a speed of, for example, 30 c/sin, and then dried.

Next, this bulb 1 is fired at 900° C. for about 10 minutes to convert the titanium compound applied to the outer surface of the bulb 1 into titanium oxide.

As a result, a high refractive index layer 81 made of titanium oxide (T 1 0 2) is formed.

Next, water is reacted with an organosilicon compound such as alkoxysilane to form an alkoxysilane condensate solution, and additives are added to this to form a silicone liquid having a predetermined concentration and viscosity.

The bulb 1 on which the high refractive index layer 81 has been formed is immersed in the silicone liquid and pulled up at a predetermined speed to adhere the silicone liquid to the outer surface of the bulb 1 . After drying this bulb 1,
By firing at a predetermined temperature, silicon oxide (S f
A low refractive index layer 82 made of O, ) is formed.

By repeating such steps alternately a plurality of times, a visible light transmitting infrared reflective film 8 having a multilayer structure in which high refractive index layers 81 and low refractive index layers 82 are alternately layered is formed.

Therefore, when the high refractive index layer 81 is coated with the titanium compound and fired at 900°C for about 10 minutes, the titanium oxide becomes a rutile or anatase crystal, and the crystal grain size of the titanium oxide reaches a maximum of 1400λ. The average particle size is 500 to 1000 particles.

This crystal structure is shown in FIGS. 3 and 4.

The function of such a halogen light bulb will be explained.

When this lamp is turned on, the filament 6 emits light, this light passes through the wall of the bulb 1, and the visible light transmitting infrared reflective film 8
to go into. Of this human light, infrared rays are reflected by the visible light transmitting infrared reflecting film 8 and returned to the filament 6. Therefore, the filament 6 is heated again by the reflected infrared rays, so power consumption is reduced and luminous efficiency is improved.

Further, visible light passes through this visible light transmitting infrared reflecting film 8 and is emitted to the outside.

In this case, the high refractive index layer 81 made of titanium oxide (TiO 2 ) according to the present invention has a crystal form of anatase, rutile, or a mixture thereof, and the crystal grain size of titanium oxide is at most 140
0, and the average particle size is 500 to 1000λ. As can be seen from the cross-sectional photograph in the film thickness direction shown in Figure 4, the porosity ρ of the titanium oxide layer is as low as about 10%, and the spaces are filled and the filling ratio of crystal grains is high. Therefore, the light transmittance and refractive index are improved, and the contact area between the crystal grains is increased, so that the mechanical strength (non-peelability) is improved.

Note that it is preferable that no voids exist in the titanium oxide layer, but according to experiments conducted by the present inventors, the porosity ρ is 30% or less when measured at several locations, and the light transmittance and refraction are The adhesive strength was improved, and there were no problems in terms of adhesion strength to the substrate.

Regarding the structure of the high refractive index layer 8 made of titanium oxide (Tie2), the results of experiments conducted by the present inventors will be described.

As mentioned above, the high refractive index layer 81 made of titanium oxide (T i 0 2 ) is formed using a solution of the titanium compound mixed in an organic solvent containing acetate as a main component.
It was found that when the firing temperature was varied for about 10 minutes, the crystal morphology and crystal grain size were different, resulting in changes in transmittance and refractive index.

The experimental data are shown in Table 1 below.

Table 1 As can be understood from Table 1 above, the firing temperature was set at approximately 550°C.
C. or higher, the refractive index is 2.1 or higher, the transmittance is 90% or higher, and good optical properties are obtained.

The refractive index gradually increases as the firing temperature increases, but when the temperature exceeds 550°C, the crystalline form changes from amorphous to anatase, and when the temperature exceeds about 900°C, many rutile crystal grains become visible.

At temperatures below about 550°C, titanium oxide (T i O 2 )
Although crystal grains are not observed under an electron microscope (SEM), as the firing temperature increases, the crystal grains become larger and the refractive index increases accordingly. At 9°C, titanium oxide crystals take on anatase and rutile forms, and as shown in the electron micrographs shown in Figures 3 and 4, the average diameter of the crystal grains is 500 to 1000 grains, and the grains are even and angular. It has a relatively spherical shape.

When the temperature exceeds 900℃, the crystal grain size of titanium oxide decreases to 1400℃.
λ, rapid growth of crystal grains occurs and clouding is observed, resulting in an extremely low transmittance.

Therefore, in order to obtain a high refractive index and high transmittance, titanium oxide crystals are required to have a crystal grain size of 1400λ or less, and more preferably 500 to 100λ.
It is better to set it to 0.

If the crystal grain size is set to 1400 or less, the contact area between the crystal grains will be large because the crystal grain size is relatively small, and the binding force and contact force of the high refractive index layer 81 will be high, and peeling will be prevented. There is also the advantage of being less.

Incidentally, depending on the composition of the raw materials, etc., crystal grain sizes exceeding 1400λ rarely occur, but there is no problem if the crystal grain size is a small number that does not affect the characteristics.

Furthermore, if the firing temperature is kept below 900°C, the crystal diameter can be made below 1400A, and at the same time, the porosity ρ in the film thickness direction can be made below 30%, which fills the spaces within the film layer. . In other words, since the porosity ρ is lowered, the light transmittance is improved, and since crystal grains are always present in the film thickness direction, peeling of the crystal grains is also reduced.

In addition, when the high refractive index layer 81 of the visible light transmitting infrared reflective film 8 exceeds 900° C., titanium oxide crystal grains grow and the crystal grains exceed 1400 If the temperature is not kept below 900℃,
There is a risk of grain growth.

Table 2 below shows the results of an experiment to reduce the bulb wall temperature to 900° C. or less during lighting.

This experiment investigated how the transmittance changes before and after heating the bulb 1.

Table 2 From the results shown in Table 2 above, the halogen bulb of the above example needs to be used under the condition that the wall temperature of the bulb 1 is 900° C. or lower.

Note that the present invention is not limited to the halogen light bulb shown in the above embodiments.

That is, in the halogen light bulb of the above embodiment, a visible light transmitting infrared reflecting film 8 was formed by alternately layering a high refractive index layer 81 made of titanium oxide and a low refractive index layer 82 made of silicon oxide on the outer surface of the bulb 1. I explained the case. This corresponds to the fourth aspect of the present invention, but the present invention is not limited to this, and can be applied to any of the first to third aspects.

The third aspect of the present invention may be a single layer optical interference film formed of titanium oxide, and in this case also, the titanium oxide thin film has a rutile or anatase crystal form and titanium oxide crystal grains. The diameter must be 1400λ or less, and the porosity ρ of the titanium oxide thin film is 3
0% or less is required.

Further, the third and fourth aspects of the present invention are not limited to halogen light bulbs, but may be ordinary incandescent light bulbs, and the shape of the bulb may also be a one-sided sealed type. The optical interference film is not limited to a visible light transmitting infrared reflecting film, but may be a selectively transmitting film.

Furthermore, the first and second aspects of the present invention are not limited to bulb bulbs, but as shown in FIGS. 3], and in such a case, the optical interference film can be applied to a protective film, an ultraviolet absorbing film, etc.

Although not shown, it is also possible to use a substrate made of metal with a reflective surface and an optical interference film made of titanium oxide similar to that described above formed thereon.

[Effects of the Invention] As explained above, according to the present invention, each invention has the following effects:
The optical interference layer made of titanium oxide (TiO2) is rutile or anatase or a crystal form thereof, and the crystal grain size of titanium oxide is the largest. 4 0 0
λ, and the porosity ρ in the film thickness direction is set to 30% or less, so the light transmittance and refractive index are improved, and the contact area between crystal grains is increased, so the mechanical strength (non-peelability) is improved. do.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the present invention, with Figure 1 being a cross-sectional view of a halogen light bulb, Figure 2 being a cross-sectional view showing a visible light transmitting and infrared reflecting film on the bulb wall, and Figure 3 being a cross-sectional view of a halogen light bulb. Figure 4 is an electron micrograph showing the crystal structure of the surface of the titanium oxide layer forming the high refractive index layer. FIG. 5 is a front view of a plate glass showing another embodiment of the present invention, and FIG. 6 is a sectional view showing an optical interference film thereof. DESCRIPTION OF SYMBOLS 1... Bulb, 5... Filament, 8... Visible light transmission infrared reflective film, 81... High refractive index layer, 82...
-Low refractive index layer, 30... Plate glass, 31... Optical interference film.

Claims (4)

[Claims] (1) In an optical interference film formed on the surface of a substrate that transmits or reflects light and having a crystal system of titanium oxide anatase or rutile, or both, the crystal grain size of the titanium oxide is 1400 Å or less. An optical interference film characterized in that the porosity in the film thickness direction is 30% or less. (2) It is formed by alternately layering a high refractive index metal oxide and a low refractive index metal oxide on the surface of a substrate that transmits or reflects light, and the high refractive index metal oxide layer is made of titanium oxide. In an optical interference film formed of a thin film having a crystal system of anatase or rutile, or both of these, the high refractive index layer made of titanium oxide has a crystal grain size of 14
00 Å or less and a porosity in the film thickness direction of 30% or less. (3) In a light-transmitting bulb having an optical interference film formed of a thin film having an anatase or rutile crystal system of titanium oxide or both on the surface of the light-transmitting bulb, the crystal grain size of the titanium oxide is 1400 Å or less. and a porosity in the film thickness direction of 30% or less. (4) A light interference film is formed by alternately layering a metal oxide with a high refractive index and a metal oxide with a low refractive index on the surface of a light-transmitting bulb, and the metal oxide layer with a high refractive index is oxidized. In a tube formed of a thin film having a crystal system of titanium anatase or rutile, or both, the high refractive index layer made of titanium oxide has a crystal grain size of 14
00 Å or less and a porosity in the film thickness direction of 30% or less.