JP2017007215A - Transparent thermal insulation material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent thermal insulation material that is composed of a small number of layers, has high transparency and thermal insulation property and is excellent in resistance to environment.SOLUTION: The transparent thermal insulation material has formed on a transparent substrate B a three-layer film composed of a reflective functional film RM and ceramic thin films CM each including a metal nitride or a metal oxynitride laminated on the top and the bottom of the reflective functional film RM. The reflective functional film RM is a nitride thin film of titanium or a titanium alloy. The transparent thermal insulation material is preferably produced by using an N-MHV sputtering method.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transparent heat insulating material in which inorganic thin films having different refractive indexes such as a ceramic thin film and a metal thin film are laminated on a transparent base material used for, for example, a building or a vehicle window, and a manufacturing method thereof. .

  A material is known that is transparent to transmit visible light and has heat insulation properties because it does not transmit infrared light. Such a material is called a transparent heat insulating sheet, a heat ray reflective film, or the like, and is commercially available. A laminated film of about 5 layers, in which an indium tin oxide layer and other metal layers and / or ceramic layers, which are generally called ITO films, are laminated is well known. The ITO film has both transparency and heat insulation, but is not necessarily suitable as a general-purpose transparent heat insulation material because indium as a raw material is expensive.

  Patent Document 1 is an invention for manufacturing a glazing for heat insulation and / or sun protection, and has silver or a silver alloy as a functional layer, titanium nitride or the like as an absorption layer, and two layers such as aluminum nitride. A multilayer structure is disclosed that includes an absorbent layer interposed between the two. The glazing of Patent Document 1 has a transmittance of about 40 to 65% under the light source D65. Each of the films shown in the examples of Patent Document 1 has a laminated structure in which 10 or more layers are laminated. Among them, the titanium nitride layer is formed to have a thickness of about 0.6 to 3 nm and absorbed. Acts as a layer.

  Patent Document 2 discloses a first element having a specific refractive index change range as a heat ray-blocking translucent member that transmits visible light and can reflect and block heat rays with high reflectivity and can be manufactured at low cost. A multilayer structure including a combination of two or more periods of the reflection layer and the second element reflection layer is disclosed, and the Si layer is used as the first element reflection layer, and AlN or TiN is used as the second element reflection layer. Has been. In the invention of Patent Document 2, it is disclosed that the converted thickness per cycle (combination of the first element reflection layer and the second element reflection layer) is preferably 0.4 to 2 μm. A laminated structure of (8 layers) is shown.

  On the other hand, Patent Document 3 is an invention that provides a highly transparent and highly heat-insulating sheet with a multilayer film having a small number of layers, and a metal thin film layer is sandwiched between ceramic layers on a substrate sheet. What has a layer structure is disclosed. The invention of Patent Document 3 is characterized by having Ag doped with 0.5 to 10 wt% of Pd, Nd and / or Ni as a metal thin film layer.

Publication pamphlet of WO2012 / 099124 JP 2003-285384 A JP 2014-218042 A

  As described above, a transparent heat insulating material having a multilayer structure of 8 layers to 10 layers or more is known. However, as the number of layers increases, the manufacturing process becomes more complicated, and an increase in cost is inevitable. On the other hand, when the number of layers is small, it is difficult not only to obtain transparent heat insulation properties, but also because it is easily affected by the external environment and has a problem with durability. It was necessary to provide etc. In view of this situation, an object of the present invention is to provide a transparent heat insulating material having a small number of layers, high transparency and heat insulation, and excellent durability.

  The inventors proceeded with studies to solve the above-mentioned problems, and came up with the idea of using a nitride thin film of titanium or a titanium alloy as the thin film of the intermediate layer. When these thin films are used, even a thin film of about 10 nm can form a laminated film with little agglomeration effect, that is, low light absorption, and can be combined with a ceramic thin film to achieve high transparency even with a three-layer structure. The inventors have found that a heat insulating property can be obtained, and that a transparent heat insulating material that is also excellent in environmental resistance because it is difficult to be oxidized can be obtained.

  That is, the present invention provides a three-layer film comprising a reflective functional film and a ceramic thin film containing metal nitride or metal oxynitride laminated on and under the reflective functional film on a transparent substrate. The present invention relates to a transparent heat insulating material, wherein the reflective functional film is a nitride thin film of titanium or a titanium alloy.

  In the present invention, the nitride thin film of titanium or titanium alloy is a titanium nitride (TiN) film or an alloy containing 0 to 99 wt% of zirconium (Zr) and / or hafnium (Hf) in titanium (Ti). The nitride thin film is preferable.

The reflective functional film is preferably a film obtained by reactive sputtering using titanium or a titanium material containing 0 to 99 wt% of zirconium and / or hafnium in titanium.
The thickness of the reflective functional film is preferably 5 to 50 nm.

  The present invention also relates to the transparent heat insulating material according to any one of the above, wherein the ceramic thin film is an aluminum nitride (AlN) film. The thickness of the ceramic thin film is preferably 20 to 100 nm.

Further, the present invention uses an N-MHV sputtering method on a transparent substrate,
Forming a ceramic thin film containing metal nitride or metal oxynitride;
Forming a reflective functional film made of nitride of titanium or titanium alloy,
The present invention relates to a method for producing a transparent heat insulating material, in which a three-layer film in which the ceramic thin films are laminated above and below the reflective functional film is formed.
The step of forming the ceramic thin film and the step of forming the reflective functional film are preferably performed at 20 ° C. to 50 ° C.

  Furthermore, this invention relates to the transparent heat insulation material manufactured by one of the said manufacturing methods.

  The transparent heat insulating material of the present invention is a material having a laminated film having a three-layer structure formed on a transparent base material, which has conventionally been difficult to realize unless it has a multilayer structure of five layers or more. High transparency and heat insulation. Further, the transparent heat insulating material of the present invention is not easily oxidized and has high durability even in a high temperature and high humidity environment.

It is typical sectional drawing of the transparent heat insulation material of this invention. An N-MHV sputtering system is shown. The transmission spectrum of the Example and comparative example of this invention is shown.

(Configuration of transparent heat insulating material)
The transparent substrate used in the transparent heat insulating material of the present invention is not particularly limited as long as the effects of the present invention can be obtained. For example, various polymer films and / or sheets (so-called plastic films) having good translucency are used. And sheets), various glasses, and the like can be used. The polymer constituting the film or sheet is not particularly limited. For example, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE) ), Triacetyl cellulose (TAC), polyvinyl chloride (PVC), polyimide (PI), polyamide (PA), and the like.

  When the base material is glass, it may be inorganic glass or organic glass, and as inorganic glass, transparent soda lime silica glass not added with a colorant, colored transparent glass colored in a desired color, etc. Examples of the organic glass include polycarbonate, polypropylene, polystyrene, and (meth) acrylic glass. These glasses may be subjected to any treatment such as chemical strengthening and physical strengthening.

  The “transparent” substrate refers to a substrate having a high visible light transmittance, and a material having a visible light transmittance of 85% or more, preferably 92% or more at a wavelength of 550 nm is used. Although the thickness of a base material is not specifically limited, Usually, the thing of about 5-250 micrometers is used. The substrate can be appropriately selected according to the use of the transparent heat insulating material and desired characteristics, and may be composed of one layer or two or more layers, and has a coating layer, a protective layer, and the like. May be. Moreover, you may have other structures, such as a release paper.

  The reflective functional film contained in the transparent heat insulating material is composed of a very thin film generally called an ultrathin film so as not to impair the light transmission. The same applies to the nitride film of titanium or titanium alloy in the present invention. The film thickness is preferably 5 to 50 nm, more preferably 7 to 25 nm. If the film thickness exceeds 50 nm, it is difficult to ensure high light transmission, and if it is less than 5 nm, light absorption or scattering occurs and transparency is lowered.

  The metal constituting the reflective functional film is titanium or a nitride of a titanium alloy. When the metal is a titanium alloy, it is preferable that titanium and zirconium and / or hafnium are contained. The content ratio of zirconium and / or hafnium is not particularly limited and can be 0 to 99 wt%, but more preferably 20 to 50 wt%. Titanium, zirconium, and hafnium are all transition metals belonging to the titanium group, and their nitrides are gold like titanium nitride and have higher infrared reflectivity than titanium nitride, improving infrared reflectivity like titanium. It is believed that

  Further, the nitride of titanium or titanium alloy constituting the reflective functional film may be doped with a metal other than zirconium and hafnium as long as the effects of the present invention are not hindered. Examples of the metal that can be doped include silicon (Si), aluminum (Al), and the like, and the doping amount can be about 2 to 10 wt%. In addition to these, the reflective functional film may contain other components as long as the effects of the present invention are not hindered.

In addition, when film formation is performed by reactive sputtering, the introduction rate of nitrogen can be arbitrarily controlled. The introduction rate of nitrogen is not particularly limited as long as the effect of the present invention can be obtained. For example, when expressed as Ti _x N _y , y is about 0.5 to 2.0 with respect to x = 1. Is preferable, and y is more preferably 0.8 to 1.0. By changing the introduction ratio of nitrogen, the photoselectivity of the film can be changed, and a reflective functional film corresponding to desired optical characteristics can be obtained.

  The reflective functional film used in the present invention has a high infrared reflectance. For example, a TiN film having a thickness of 10 nm has a reflectance of about 65% at a wavelength λ = 1000 nm. The reflectance is preferably higher than about 60%, more preferably 65% or more. This value is comparable to the reflectance (60%) under the same conditions of an Ag thin film which is a known thin film having a high infrared reflectance.

  Further, a nitride thin film of titanium or titanium alloy is not easily oxidized and has good environmental resistance such as acid resistance, alkali resistance, and weather resistance. The Ag thin film has a problem that it is susceptible to oxidation in a high temperature and high humidity environment, but the nitride thin film of titanium or titanium alloy has excellent infrared reflectivity (heat insulation) and environmental resistance. A transparent heat insulating material is obtained.

  A ceramic thin film of one layer is formed above and below the above-described reflective functional film. In this specification, “upper” or “lower” of the reflective functional film means “lower” the side closer to the base material and the side far from the base material in the positional relationship between the base material and the reflective functional film. This is referred to as “upper”.

The ceramic thin film of the transparent heat insulating material of the present invention is a ceramic thin film containing a metal nitride or a metal oxynitride, and is preferably a nitride film and / or an oxynitride film of aluminum and / or an aluminum alloy. Specific examples of the ceramic thin film include an aluminum nitride film formed by reactive sputtering using nitrogen. In the reactive sputtering method, an aluminum nitride film is obtained by depositing aluminum and / or an aluminum alloy as a target and a gas obtained by mixing a nitrogen gas having a flow rate ratio of 0.1 to 50% into an argon gas as a sputtering gas. It is done. The rate of introduction of nitrogen into aluminum can be controlled by film forming conditions such as partial pressure of nitrogen gas and sputtering power. When expressed as AlN _x , the value of x is about 0.7 to 1.0. Preferably there is.

  As the aluminum component, pure aluminum (for example, one having a purity of 99.9 to 99.999%) or an aluminum alloy is used. The aluminum alloy may be a general alloy made of aluminum, Sn, Ti, or the like, and a small amount of one or more metals selected from Nd, Ni, Ag, Cu, Sn, Pd, and Ti (0.1). 10 wt%) added aluminum alloy may be used. Among these, an aluminum alloy to which 0.1 to 10 wt% of Cu, Sn and / or Ti is added is preferable.

  The thickness of the ceramic thin film can be 20 to 100 nm, and more preferably 20 to 60 nm. Since the transmittance of the ceramic thin film is improved by the antireflection effect due to light interference, there is a film thickness region corresponding to the refractive index of the film, and the transmittance decreases if it is too thick or too thin. If the thickness is less than 20 nm or exceeds 100 nm, the antireflection effect in the visible light region is reduced, so that the transmittance is lowered and the transmittance in the infrared region is increased. The thicknesses of the ceramic thin films formed above and below the reflective functional film may be the same, or the film thickness may be different between the upper film and the lower film.

  The thickness (thickness not including the base material) of the three-layer structure composed of the ceramic thin film and the reflective functional layer is 45 to 250 nm, more preferably 70 to 150 nm, and still more preferably 80 to 120 nm. This film thickness range is derived from the optimum values of the respective film thicknesses of the ceramic thin film and the reflective functional layer. If the thickness is less than 45 nm or more than 250 nm, the transmittance decreases, which is not preferable.

  The combination of the thickness of the ceramic thin film and the reflective functional film can be appropriately selected in accordance with the application and desired characteristics within the above range. For example, the ceramic thin film is 30 to 50 nm and the reflective functional film is 5 When combined as ˜15 nm, a transparent heat insulating material having particularly suitable transparent heat insulating properties can be obtained. By changing the combination of the thickness of the reflective functional film and the ceramic thin film, a transparent heat insulating material having desired visible light transmittance and infrared reflectance can be obtained.

The schematic diagram of the cross section of the transparent heat insulation material of this invention is shown in FIG.
The transparent heat insulating material shown in FIG. 1 has a laminated film of three layers laminated on a plastic substrate sheet B, and the laminated film is refracted on both upper and lower sides of a reflective functional film RM made of, for example, titanium nitride. The structure is sandwiched between ceramic films CM which are aluminum nitride thin films having a high rate (refractive index 2.1).

  The transparent heat insulating material of the present invention may have a known configuration such as an undercoat layer and a topcoat layer in addition to the base material, the ceramic thin film, and the reflective functional film. Since it is excellent in environmental resistance, it can be configured without including a topcoat layer, and higher transparency may be realized.

(Production method)
The transparent heat insulating material of the present invention is generally produced by sequentially forming a ceramic thin film and a reflective functional film on a substrate. Examples of the method for forming the ceramic thin film and the reflective functional film include a physical vapor deposition (PVD) method such as a vacuum vapor deposition method and a sputtering method, a chemical vapor deposition (CVD) method, and the like. As a more preferable film forming method, there is a New Magnetic Hollow-cathode V-type sputtering method (sometimes called an N-MHV sputtering method) which is a kind of PVD method. According to such a method, an excellent reflective functional film and A ceramic thin film can be formed stably.

  The N-MHV sputtering method is described in detail in Japanese Patent No. 4473852, and is a sputtering method capable of forming a film at a lower temperature and lower damage than a normal magnetron sputtering method. This method is based on the FTS method.

  According to the N-MHV sputtering method, compared to the general magnetron sputtering method, it is possible to form a film with extremely low energy (sputtering voltage of −300 V or less) by generating high-density plasma with opposed double magnetic poles. In the ultrathin film, a high-quality thin film with a uniform composition and few defects can be obtained in a low-temperature process, and the film uniformity and the film surface smoothness can be improved. The thin film formed by reactive sputtering using the N-MHV sputtering method has sufficient reactivity under high-density plasma, and can form a ceramic thin film with a smooth surface and low absorption. A laminated film can be obtained without damaging the surface of the thin film or ceramic thin film.

  FIG. 2 shows details of the N-MHV sputtering apparatus. The N-MHV sputtering apparatus is described in detail in Japanese Patent No. 4473852. The sputtering apparatus 1 includes a target holder 11a, 11b in which a pair of targets 10a, 10b are arranged at the tip, a vacuum chamber 2, and a sputtering power supply. Power supply 3, substrate holder 4, exhaust device 5, and gas supply device 6.

  When forming a film using an N-MHV sputtering apparatus, a metal material (for example, metal aluminum) that becomes a nitride and / or an oxide is used for the targets 10a and 10b, and a base material sheet B to be formed is used as a substrate. The holder 4 is set, the vacuum chamber 2 is evacuated to a predetermined degree of vacuum, a predetermined amount of sputtering gas (argon gas) and reactive gas (nitrogen gas and / or oxygen gas) is added, and a predetermined sputtering power and sputtering are obtained. Sputter by time. By this sputtering, a ceramic thin film having a predetermined thickness is formed on the base sheet B.

  Subsequently, a reflective functional film is formed. The reflective functional film is basically formed by the same process as the ceramic thin film, but a base material having a ceramic thin film on the surface using a metal material (for example, metal titanium) as a nitride for the targets 10a and 10b. Is set on the substrate holder 4, the vacuum chamber 2 is evacuated to a predetermined degree of vacuum, a predetermined amount of sputtering gas (argon gas) and reaction gas (nitrogen gas) is added, and sputtering is performed with a predetermined sputtering power and sputtering time. I do. By this sputtering, a reflective functional film having a predetermined thickness is formed on the ceramic thin film.

  Further, a ceramic thin film is formed on the reflective functional film by the above-described process to obtain a transparent heat insulating material having a three-layer laminated structure on the base material. After film formation using an N-MHV sputtering apparatus, a topcoat layer may be formed on the surface of the transparent heat insulating material according to a known method, if necessary.

  According to the above-described method, the film formation process can be performed without heating the substrate sheet B or the vacuum chamber 2 (at room temperature), and the film formation can be performed without heating the substrate sheet. A good thin film can be obtained. By performing film formation at room temperature (about 20-50 ° C) without heating the substrate, low damage film formation is possible, and a more uniform thin film with fewer defects can be obtained. Selection between visible light and infrared light A transparent heat insulating sheet having high absorbability can be obtained.

The transparent insulation sheet of the Example and comparative example of this invention was created in the following procedure.
As a base sheet, a 100 mm × 100 mm × 100 μm PET film (visible light transmittance of 92% at a wavelength of 500 nm) was degreased, washed and dried. A predetermined thin film was formed on the film by the N-MHV sputtering apparatus shown in FIG. Various thin films were formed under the following conditions.

1. Formation of Aluminum Nitride Film Aluminum Al (purity 5N), 125 mm × 300 mm was used as a target.
The Al was placed on a target holder, and the PET film was set on a substrate holder. Subsequently, after evacuating the inside of the vacuum chamber to 10 ⁻⁵ Pa or less, argon gas as a sputtering gas and nitrogen gas as a reaction gas are sequentially supplied, and the inside of the vacuum chamber is argon gas 0.3 Pa, nitrogen gas 0 15 Pa. The sputtering power was 500 W, and the sputtering time was adjusted according to the desired film thickness to obtain an aluminum nitride thin film having a predetermined film thickness.

2. Formation of Titanium Nitride Thin Film Titanium Ti (purity 5N), 125 mm × 300 mm was used as a target.
Install the Ti on the target holder. Then, a PET film having an aluminum nitride thin film formed thereon was set on a substrate holder. Subsequently, after evacuating the inside of the vacuum chamber to 10 ⁻⁵ Pa or less, argon gas as a sputtering gas and nitrogen gas as a reaction gas are sequentially supplied, and the inside of the vacuum chamber is argon gas 0.3 Pa, nitrogen gas 0 15 Pa. The sputtering power was 500 W, the sputtering time was adjusted according to the desired film thickness, and a titanium nitride thin film having a predetermined film thickness was obtained.

[Example 1] AlN / TiN / AlN multilayer film Based on the above film formation conditions, a multilayer film of AlN (30 nm) / TiN (10 nm) / AlN (30 nm) was prepared. The film formation (sputtering) time for the AlN 30 nm thin film was 10 minutes, and the film formation (sputtering) time for the TiN 10 nm thin film was 2 minutes.

[Example 2]
A laminated film was prepared in the same manner as in Example 1 except that the AlN film on the base sheet side was 50 nm (sputtering time 17 minutes) and the AlN film on TiN was 40 nm (sputtering time 13 minutes).

[Comparative Example 1] AlN / Ag / AlN laminated film A laminated film was prepared in the same manner as in Example 1 except that AgPd (Pd doping amount 2 wt%) was used instead of titanium nitride as the reflective functional layer. did.

[Comparative Example 2] AlN / Ag / AlN multilayer film A multilayer film was prepared in the same manner as in Example 2 except that AgPd (Pd doping amount 2 wt%) was used instead of titanium nitride as the reflective functional layer. did.

[Reference Example] ITO / Ag / ITO / Ag / ITO Multilayer Film A transparent heat insulating material containing a known ITO / Ag / ITO / Ag / ITO 5-layer film was used.

<Evaluation of transparent heat insulation>
Visible light transmittance (transmittance (%) at a wavelength of 550 nm) and infrared transmittance (transmittance (%) at a wavelength of 1000 nm) of the transparent heat insulating materials of Examples 1, 2, Comparative Examples 1, 2 and Reference Example It is shown in Table 1 below. The transmittance was measured using a spectrophotometer HUS-100S manufactured by Asahi Spectrometer Co., Ltd., with reference to each substrate.

  As shown in Table 1, the transparent heat insulating materials of Examples 1 and 2 had the same visible light transmittance and lower infrared transmittance than the transparent heat insulating materials of Comparative Examples 1 and 2. . Moreover, the transparent heat insulation material of Examples 1 and 2 showed the visible light transmittance and infrared transmittance equivalent to a reference example.

<Evaluation of environmental resistance>
With respect to the transparent heat insulating materials of Example 2, Comparative Example 2 and Reference Example, a high temperature and high humidity environment test of 65 ° C. × 95% RH was performed, and the film alteration occurrence time until film alteration such as whitening / blackening occurred It was measured. The results are shown in Table 2.

  As shown in Table 2, the transparent heat insulating material of Example 2 did not cause film alteration even after 1000 hours. On the other hand, in Comparative Example 2 containing Ag as an intermediate film, white spots occurred in 400 to 500 hours. In the reference example, which is a five-layer film of ITO and Ag, white spots occurred in 700 to 800 hours.

  In FIG. 3, the transmission spectrum of the film | membrane of Example 2 and Comparative Example 2 is shown. As shown in FIG. 3, Example 2 has a lower transmittance than that of Comparative Example 2, particularly in the infrared region (wavelength of about 800 nm or more), that is, the result of being less likely to transmit infrared rays (high heat insulation).

  As described above, the transparent heat insulating material of the embodiment of the present invention has the same or superior light transmission characteristics as the five-layer film containing ITO, and is excellent in the infrared shielding performance as compared with the three-layer film containing Ag. It was also confirmed that it was a transparent heat insulating material excellent in environmental resistance.

DESCRIPTION OF SYMBOLS 1 Sputtering device 2 Vacuum chamber 3 Power supply for sputter power supply 4 Substrate holder 5 Exhaust device 6 Gas supply device 6 ′ Sputter gas introduction supply port 6 ″ Reaction gas supply ports 10a and 10b Targets 10a ′ and 10b ′ Sputtering surfaces (opposing surfaces) )
11a, 11b Target holders 12a, 12b Backing plates 20a, 20b Inter-target magnetic field generating means 30a, 30b Auxiliary magnetic field generating means K Plasma generating space B Base sheet B 'Film forming surface RM Reflective functional film CM Ceramic thin film

Claims (9)

On a transparent substrate, a three-layer film composed of a reflective functional film and a ceramic thin film containing metal nitride or metal oxynitride laminated on and under the reflective functional film is provided, A transparent heat insulating material, wherein the reflective functional film is a nitride thin film of titanium or a titanium alloy. 2. The transparent heat insulating material according to claim 1, wherein the titanium or titanium alloy nitride thin film is a titanium nitride film or an alloy nitride film containing 0 to 99 wt% of zirconium or hafnium in titanium. The reflective functional film is a film obtained by depositing titanium or a titanium material containing 0 to 99 wt% of zirconium and / or hafnium in titanium by a reactive sputtering method. 2. The transparent heat insulating material according to 2. The transparent heat insulation material of any one of Claims 1-3 whose thickness of the said reflective functional film is 5-50 nm. The transparent heat insulating material according to claim 1, wherein the ceramic thin film is an aluminum nitride film. The transparent heat insulation material of any one of Claims 1-5 whose thickness of the said ceramic thin film is 20-100 nm. Using a N-MHV sputtering method on a transparent substrate,
Forming a ceramic thin film containing metal nitride or metal oxynitride;
Forming a reflective functional film made of nitride of titanium or titanium alloy,
A method for producing a transparent heat insulating material, wherein a three-layer film in which the ceramic thin films are laminated on and under the reflective functional film is formed. The method for producing a transparent heat insulating material according to claim 7, wherein the step of forming the ceramic thin film and the step of forming the reflective functional film are performed at 20 ° C to 50 ° C. The transparent heat insulation material manufactured by the manufacturing method in any one of Claim 7 or 8.

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