阅读说明：本技术 红外线反射基板 (Infrared reflection substrate ) 是由 绀谷友广 大森裕 于 2018-05-24 设计创作，主要内容包括：本发明提供兼具高可见光透射率和高隔热性的红外线反射基板。本发明的红外线反射基板具备透明基材和红外线反射层,其中,红外线反射基板的可见光吸收率为0.3以下,红外线反射基板在700nm下与在600nm下的反射率的斜率为0.12以上。(The invention provides an infrared reflective substrate having both high visible light transmittance and high heat shielding property. The infrared reflective substrate of the present invention comprises a transparent base material and an infrared reflective layer, wherein the visible light absorptance of the infrared reflective substrate is 0.3 or less, and the reflectance gradient between the infrared reflective substrate at 700nm and at 600nm is 0.12 or more.)

1. An infrared-reflective substrate comprising a transparent base material and an infrared-reflective layer provided on the base material,

the infrared-reflective substrate has a visible light absorptance of 0.3 or less,

the slope dR of the reflectivity of the infrared reflecting substrate at 700nm and 600nm_700-600Is a content of at least 0.12,

the reflectance of the infrared reflective substrate from the transparent base material side at a wavelength of 600nm is represented by R₆₀₀(%), wherein R represents the reflectance at a wavelength of 700nm from the transparent substrate side₇₀₀(%) slope dR of the reflectance_700-600(%/nm) in dR_700-600＝(R₇₀₀-R₆₀₀) And/100 (nm).

2. The infrared reflective substrate of claim 1,

the reflectivity R₆₀₀Is 10% or more and 60% or less.

3. The infrared reflective substrate according to claim 1 or 2,

the reflectivity R₇₀₀Is 25% to 85%.

4. The infrared reflective substrate according to any one of claims 1 to 3,

the reflectivity R₇₀₀With respect to the reflectivity R₆₀₀Ratio R of₇₀₀/R₆₀₀Is 1.2 or more.

5. The infrared reflective substrate according to any one of claims 1 to 4,

the peak wavelength of visible light transmittance is 450 nm-650 nm.

6. The infrared reflective substrate according to any one of claims 1 to 5,

the transparent substrate is a film, and the transparent substrate is a transparent film,

the transparent substrate is provided with an adhesive layer on the surface opposite to the surface provided with the infrared reflection layer.

7. The infrared reflective substrate according to any one of claims 1 to 5,

the transparent substrate is glass.

8. The infrared reflective substrate according to any one of claims 1 to 7,

the infrared-reflective substrate further includes a transparent protective film on the infrared-reflective layer.

Technical Field

The present invention relates to an infrared-reflective substrate having a thin film of an infrared-reflective layer on a transparent base.

Background

Conventionally, there has been known an infrared-reflective substrate including an infrared-reflective layer on a base material such as glass or film. Such an infrared-reflective substrate reflects near infrared rays such as sunlight incident from the outside into a room and exhibits a heat-insulating effect, for example, by using glass as a base material and integrating an infrared-reflective layer formed on the indoor side thereof with a window glass, or by bonding a film as a base material to the indoor side of a window glass. Of course, the present invention can be applied to other applications such as showcases, which require blocking of light from the outside, besides the window glass.

In such an infrared reflective substrate, it is considered that the higher the heat shielding property is, the more preferable it is, but if the heat shielding property is increased, the transmittance of visible light is lowered, and visibility from the inside is deteriorated. That is, in the conventional art, the heat insulating property can be improved by lowering the transmittance of light, but if the heat insulating property is improved by lowering the transmittance in this way, the visible light transmittance is also lowered. Therefore, in recent years, it has been desired to have both high light-shielding properties and high visible light transmittance.

For example, in a region near the equator such as southeast asia where the temperature is high and the heat ray from sunlight is strong, the visible light transmittance may be as low as about 40%, but an infrared reflective substrate having a higher heat insulating property such as a heat insulating coefficient of 0.25 or less is required. On the other hand, depending on the region, from the viewpoint of design and appearance, it is sometimes required to achieve heat insulation having a heat insulation coefficient of 0.5 or less while maintaining a high visible light transmittance of 65% or more.

As such an infrared-reflective substrate, patent document 1 discloses an infrared-reflective film including two metal layers. The infrared reflective film is aimed at having a low total solar energy transmittance while having a high visible light transmittance.

Disclosure of Invention

Problems to be solved by the invention

However, since the heat shielding property and the visible light transmittance are in a trade-off relationship, it has been difficult to achieve both high heat shielding property and high visible light transmittance. In the conventional infrared reflective substrate, for example, when the visible light transmittance is high and 70%, the thermal insulation coefficient exceeds about 0.55. The infrared reflective substrate having a low visible light transmittance of 40% is more than about 0.35. Actually, it is known that examples 1 and 2 of the infrared reflective film disclosed in patent document 1 have visible light transmittances as high as 77% and 78%, but the solar heat extraction yield (TSHT) is 55 and 53, and the values thereof are high as 62.5 and 60.2 in terms of shielding coefficients, and the heat insulating properties of both examples 1 and 2 are low.

The present invention addresses the problem of providing an infrared-reflective substrate having both high visible light transmittance and high heat-shielding properties.

Means for solving the problems

Even though the conventional infrared reflective substrate has high heat insulation properties, it has a disadvantage that the reflectance in the visible light region is high and the visible light transmittance is accordingly low as is clear from, for example, the spectrum of fig. 9 b. The conventional infrared-reflective film shown in the spectrum of fig. 10b has the following reflection characteristics: considering that the wavelength region of visible light is generally 400nm to 700nm, the reflectance is suppressed and the transmittance is improved up to the vicinity of the wavelength of 700 nm; the reflectance of light is improved from the vicinity of 750nm to the long wavelength side. However, it is difficult to design the infrared reflective substrate such that the reflectance thereof sharply increases from a specific wavelength. Therefore, even if the infrared-reflective substrate is designed so that the reflectance is increased from near 750nm, the reflectance is not sufficiently increased in the near infrared region, and a large amount of near infrared light is transmitted through the infrared-reflective substrate. As a result, the heat insulation property of the infrared ray reflection substrate is lowered due to the transmission of near infrared rays.

On the other hand, the sensitivity of the human eye varies depending on the wavelength even in the visible light region, and is not uniform. For example, even in the visible light region, the sensitivity of the human eye to light having a wavelength near 550nm and light having a wavelength near 700nm is lower than that to light having a wavelength near the center of the visible light region. Therefore, when the visible light transmittance is calculated so as to correspond to the luminance actually felt by a human, it is calculated by multiplying the ratio of the light actually transmitted by a weight coefficient determined for each wavelength corresponding to the sensitivity of the eye. Fig. 1 is a graph showing a weight coefficient for calculating visible light transmittance. In fig. 1, the horizontal axis represents wavelength and the vertical axis represents weight coefficient. According to FIG. 1, the weight coefficient is highest at a wavelength of 550nm, showing a value close to 10, while in the range of 650nm to 700nm the weight coefficient reaches 1 or less.

In view of the fact that the sensitivity of the eye is low and the weight coefficient of visible light transmittance is low even in the vicinity of the long wavelength boundary in the visible light region, the infrared reflective substrate of the present invention can achieve both high visible light transmittance and low thermal insulation coefficient by increasing the slope of reflectance on the long wavelength side in the visible light region to suppress the influence on visible light transmittance and to improve the reflectance of near infrared light.

In one embodiment, the present invention provides an infrared-reflective substrate comprising a transparent base material and an infrared-reflective layer, wherein the infrared-reflective substrate has a visible light absorptance of 0.3 or less, and the infrared-reflective substrate has a reflectance gradient dR between 700nm and 600nm_700-600Is 0.12 or more, and the reflectance of the infrared reflective substrate from the transparent base material side at a wavelength of 600nm is R₆₀₀(%), and the reflectance from the transparent substrate side at a wavelength of 700nm is defined as R₇₀₀(%) slope dR of the reflectance_700-600(%/nm) in dR_700-600＝(R₇₀₀-R₆₀₀) And/100 (nm).

The above reflectance R₆₀₀Preferably 10% or more and 60% or less. This is because the visible light transmittance can be improved by reducing the reflectance at a wavelength of 600 nm. In additionIn addition, the above reflectance R₇₀₀Preferably 25% or more and 85% or less. This is because by increasing the reflectance at a wavelength of 700nm, the shielding coefficient can be reduced while the influence on the visible light transmittance is kept to a low level. Further, it is preferable that the ratio of the reflectance at a wavelength of 700nm to the reflectance at a wavelength of 600nm is 1.2 or more. By increasing the ratio of the reflectance, the polarizing film laminate can have both visible light transmittance and shielding coefficient at a higher level. The visible light transmittance can be improved by setting the visible light transmittance peak wavelength to 450nm to 650 nm. The transparent substrate may be a film, and the surface of the transparent substrate opposite to the surface having the infrared-reflecting layer may be provided with a pressure-sensitive adhesive layer, or the transparent substrate may be glass. The infrared reflective substrate may further include a transparent protective film on the infrared reflective layer, thereby improving durability.

Since the thermal insulation coefficient decreases if the amount of light transmitted (transmittance) is reduced, the Visible Light Transmittance (VLT) and the Shielding Coefficient (SC) are in a trade-off relationship, and the characteristics of the infrared reflective film considering both parameters can be represented by VLT (%) -160 × SC, for example. The basis of this equation is that the shielding factor can be reduced by approximately 1/160 at the expense of 1% visible light transmittance. In one embodiment, the infrared reflective substrate of the present invention may have a characteristic of-12 or more in VLT (%) -160 XSC. Further, the value is more preferably 0 or more, still more preferably 10 or more, and still more preferably 15 or more. In consideration of other factors such as durability, the parameter may be set to 20 or less, or may be set to 17 or less.

ADVANTAGEOUS EFFECTS OF INVENTION

The infrared reflective substrate of the present invention has both high visible light transmittance and low thermal insulation coefficient.

Drawings

Fig. 1 is a graph showing a weight coefficient for calculating visible light transmittance.

Fig. 2 is a cross-sectional view schematically showing an example of the configuration of an infrared-reflective substrate that is an embodiment of the present invention.

Fig. 3 is a cross-sectional view schematically showing an example of a usage mode of infrared reflection.

Fig. 4 is a graph showing transmittance and reflectance of the infrared reflective substrate according to the embodiment of the present invention with respect to light incident from the base material side.

Fig. 5 is a schematic view showing a layer structure of an infrared-reflective substrate 500 according to an embodiment of the present invention.

Fig. 6 is a schematic view showing a layer structure of an infrared-reflective substrate 600 according to an embodiment of the present invention.

Fig. 7 is a schematic diagram showing the layer structure of embodiment 1.

Fig. 8 is a schematic diagram showing the layer structure of example 8.

Fig. 9a is a graph showing the optical characteristics of example 1.

Fig. 9b is a graph showing the optical characteristics of comparative example 1.

Fig. 10a is a graph showing the optical characteristics of example 9.

Fig. 10b is a graph showing the optical characteristics of comparative example 4.

Fig. 11 is a graph showing the relationship between the shielding coefficient and the visible light transmittance in the examples of the present invention and the comparative examples.

Description of the symbols

100 infrared ray reflective substrate

10 transparent substrate

20 infrared reflective layer

50 window glass

60 adhesive layer

500 infrared reflective layer 500

510 st stack

512 st metal oxide layer

514 metal layer 1

516 2 nd metal oxide layer

530 transparent spacer layer

550 nd 2 nd laminate

552 No. 3 Metal oxide layer

554 metal layer 2

556 th metal oxide layer 4

600 infrared ray reflection substrate

612 st metal oxide layer

614 metal layer 1

616 nd 2 nd metal oxide layer

618 metal layer 2

620 rd metal oxide layer

622 metal layer No. 3

624 th metal oxide layer

Detailed Description

Fig. 2 is a cross-sectional view schematically showing an example of the configuration of an infrared-reflective substrate that is an embodiment of the present invention. As shown in fig. 2, the infrared-reflective substrate 100 includes an infrared-reflective layer 20 on one main surface of a transparent base 10. In the present embodiment, the infrared reflection layer 20 is in direct contact with the transparent substrate 10, but another layer may be provided therebetween. For example, an undercoat layer may be provided between the infrared-reflective layer 20 and the transparent substrate 10 in order to improve durability. A transparent protective film (not shown) for protecting the infrared-reflective layer 10 may be provided on the upper surface of the infrared-reflective layer, that is, on the main surface on the opposite side of the transparent substrate 10.

Fig. 3 is a cross-sectional view schematically showing an example of a usage mode of infrared reflection for briefly explaining the function of the infrared reflection substrate. In this usage mode, the transparent base of the infrared-reflective substrate is a film base. The infrared reflective substrate 100 is used by bonding a main surface on the transparent base side to the indoor side of a window glass 50 of a building or an automobile via an adhesive layer 60 or the like. As shown in fig. 3, the infrared-reflective substrate 100 transmits visible light (VIS) from the outside and guides the visible light into the room, and the infrared-reflective layer 20 reflects near infrared light (NIR) from the outside. By the reflection of the near infrared rays, heat rays from the outside to the inside of the room due to sunlight or the like can be suppressed (a heat insulating effect is exerted), and therefore, the cooling efficiency in summer can be improved.

Fig. 4 is a graph showing a typical example of the transmittance and reflectance of the infrared-reflective substrate 100 according to the embodiment of the present invention with respect to light incident from the base material side. The horizontal axis represents wavelength (nm) and the vertical axis represents transmittance (%) and reflectance (%). In fig. 4, the infrared reflective substrate is attached to a single glass sheet according to JIS a5759-2008 (architectural window glass film). In order to examine the tendency of any one of transmission, reflection, and absorption of light incident on the infrared-reflective substrate, a value obtained by subtracting the transmittance and reflectance from 100% was defined as the absorptance.

The infrared-reflective substrate 100 has a transmittance of about 70% at 400nm to 550nm corresponding to the short wavelength side in the visible light region, and a reflectance of about 10% at the same time. The reflectance becomes higher from near 550nm to the long wavelength side, and the reflectance exceeds 50% at 700nm near the boundary of the long wavelength side reaching the visible light region. Further, the infrared reflective substrate 100 has a reflectance of more than 50% at a wavelength near the visible region, i.e., 700nm to 800nm in a near-infrared region having a longer wavelength than the visible region. The reason why the near-infrared region has a high reflectance of more than 50% at 700nm to 800nm near the visible region is that the reflectance has a high slope in the wavelength region of 600nm to 700 nm. Therefore, the infrared reflective substrate 100 has high light reflectance even in the near-infrared region near the visible region, and therefore has high heat insulation properties and a heat insulation coefficient of 0.50.

In the present application, the slope of the reflectance is determined based on the definition described in mathematical formula 1.

[ mathematical formula 1]

d R_{λupper-λlower}＝(R_λupper(%)-R_λlower(%))/(λ_upper-λ_lower)(nm)

λ: wavelength (nm) (upper represents wavelength on long wavelength side, lower represents wavelength on short wavelength side)

R_λ: reflectance at wavelength λ (%)

dR_{λupper-λlower}: slope of reflectance between wavelength lambda upper and wavelength lambda lower (%/nm)

Since the infrared reflective substrate 100 is designed such that the reflectance is increased from 600nm to 700nm in the wavelength range, the transmittance is decreased. However, as shown in fig. 1, the weight coefficient in the visible light transmittance calculation is low at wavelengths of 600nm to 700nm, and therefore, the influence on the visible light transmittance is small. Therefore, for the infrared reflective substrate 100, although the heat shielding property is high, the visible light transmittance has a value as high as 68%.

Preferred embodiments of the structure, material, and the like of each layer will be described below in order.

[ transparent base Material ]

As the transparent substrate 10, a transparent substrate having a visible light transmittance of 80% or more can be suitably used. The visible light transmittance can be measured, for example, according to JIS a5759-2008 (architectural window glass films).

The thickness of the transparent substrate 10 is not particularly limited, but is typically about 10 μm to 10 mm. As the transparent substrate, a glass plate, a flexible transparent resin film, or the like can be used. From the viewpoint of improving productivity of the infrared reflective substrate and facilitating the application when the infrared reflective substrate is bonded to a window glass or the like, a flexible transparent resin film can be suitably used as the transparent substrate 10. When a transparent resin film is used as the transparent substrate, the thickness thereof is preferably in the range of about 10 to 300 μm, preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 40 μm or less. In addition, since processing at high temperature may be performed when forming a metal layer, a metal oxide layer, or the like on the transparent base material 10, it is preferable that the resin material constituting the transparent resin film base material is a material having excellent heat resistance. Examples of the resin material constituting the transparent resin film substrate include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), and Polycarbonate (PC).

When the transparent substrate 10 is a transparent resin film substrate, a material having a cured resin layer on the surface of the transparent film may be suitably used in addition to the transparent film for the purpose of improving the mechanical strength of the infrared-reflective substrate. Further, by providing a cured resin layer on the side of the transparent film on which the infrared-ray reflective layer 20 is formed, the scratch resistance of the infrared-ray reflective layer 20, the transparent protective layer that can be formed thereon, and the like tends to be improved. The cured resin layer 12 can be formed by, for example, applying a cured film of an appropriate ultraviolet curable resin such as acrylic resin or silicone resin to a transparent film. As the cured resin layer, a material having high hardness can be suitably used.

For the purpose of improving adhesion or the like, the surface of the transparent base 10 on which the infrared-reflective layer 20 is formed may be subjected to surface modification treatment such as corona treatment, plasma treatment, flame treatment, ozone treatment, undercoating treatment, glow treatment, saponification treatment, treatment with a coupling agent, or the like.

[ adhesive layer ]

When the transparent substrate 10 is a resin film substrate, an adhesive layer 60 or the like for bonding an infrared-reflective substrate to a window glass or the like may be provided on the surface of the transparent substrate 10 opposite to the surface on which the infrared-reflective layer 20 is formed. The pressure-sensitive adhesive layer 60 preferably has a high visible light transmittance and a small refractive index difference from the transparent substrate 10, and for example, an acrylic pressure-sensitive adhesive (a pressure-sensitive adhesive) is suitable as a material of the pressure-sensitive adhesive layer provided on the transparent film substrate because it is excellent in optical transparency, exhibits appropriate wettability, cohesiveness and adhesiveness, and is excellent in weather resistance, heat resistance and the like.

The adhesive layer 60 preferably has a high visible light transmittance and a low ultraviolet light transmittance. By reducing the ultraviolet transmittance of the pressure-sensitive adhesive layer 60, deterioration of the infrared-ray reflective layer due to ultraviolet rays such as sunlight can be suppressed. The pressure-sensitive adhesive layer preferably contains an ultraviolet absorber from the viewpoint of reducing the ultraviolet transmittance of the pressure-sensitive adhesive layer. By using a transparent film base material or the like containing an ultraviolet absorber, deterioration of the infrared reflecting layer due to ultraviolet rays from the outside can be suppressed. For the purpose of preventing contamination of the exposed surface of the pressure-sensitive adhesive layer before the infrared-reflective substrate is actually used, it is preferable to temporarily attach and cover the exposed surface with a separator. Thus, contamination due to contact between the exposed surface of the adhesive layer and the outside can be prevented in a normal processing state.

Even when the transparent base material 10 is a flexible film, an infrared-reflective substrate may be used by being incorporated into a housing or the like as disclosed in patent document 2. In this embodiment, since the adhesive layer 60 is not required to be provided on the transparent base material 10, absorption of far infrared rays by the adhesive layer does not occur. Therefore, by using a material (for example, cyclic polyolefin) having a small content of functional groups such as C ═ C bond, C ═ O bond, C — O bond, and aromatic ring as the transparent base material 10, the infrared ray from the transparent base material 10 side can be reflected by the infrared ray reflection layer 20, and heat insulation can be provided to both sides of the infrared ray reflection base material. Such a configuration is particularly useful in, for example, a refrigerated showcase, or the like.

[ Infrared reflecting layer ]

The infrared reflective layer 20 in the embodiment of the present invention has a high slope of the reflectance of light in the wavelength range from 600nm to 700nm, and the following embodiments are possible, for example, but the present invention is not limited to these embodiments.

< 2 Metal layer Structure

Fig. 5 shows an infrared reflective layer 500 in an embodiment of the invention. The infrared ray reflection layer 500 in fig. 5 forms a fabry-perot resonator from 2 metal layers. The 2 metal layers act as a half mirror in a fabry-perot resonator. Wherein a transparent spacer layer is disposed between the 2 metal thin films to selectively transmit light of a specific wavelength and reflect or interfere/attenuate light of other wavelengths, thereby shielding the light. In the fabry-perot resonator, the wavelength range of transmitted light and the wavelength range of reflected light can be changed by adjusting the optical film thickness (product of refractive index and physical film thickness) of the transparent spacer layer between the 2 metal thin films.

The infrared reflective layer 500 includes a 1 st laminate 510, a transparent spacer 530, and a 2 nd laminate 550 in this order from the substrate 10 side. The 1 st stacked body 510 includes a 1 st metal oxide layer 512, a 1 st metal layer 514, and a 2 nd metal oxide layer 516 in this order from the substrate 10 side, and the 2 nd stacked body includes a 3 rd metal oxide layer 552, a 2 nd metal layer 554, and a 4 th metal oxide layer 556 in this order from the substrate 10 side. The 1 st metal layer 514 and the 2 nd metal layer 554 correspond to the 2 nd metal layer described above which functions as a half mirror. The 1 st metal layer is in direct contact with the 1 st metal oxide layer and the 2 nd metal oxide layer, but another layer may be included between them in order to protect the metal layer or to adjust the refractive index difference at the interface. Similarly, the 2 nd metal layer is in direct contact with the 3 rd metal oxide layer and the 4 th metal oxide layer, but other layers may be included therebetween.

< Metal layer >

The metal layers 514 and 554 have a core role of infrared reflection. As the material of the metal layers 514 and 554, a metal having a high reflectance of near infrared rays such as silver, gold, copper, and aluminum is preferably used. Among them, a silver alloy layer containing silver as a main component can be suitably used as the metal layer sandwiched between the metal oxide layers from the viewpoint of improving the visible light transmittance and the near infrared reflectance without increasing the number of stacked layers. Since silver has a high free electron density, it can realize a high reflectance of near infrared rays/far infrared rays, and an infrared reflective film having excellent heat insulating effect and heat insulating effect can be obtained even when the number of layers constituting the infrared reflective layer 20 is small.

The metal layers 514 and 554 preferably contain 75 to 99.9 wt% of silver. The content of silver in the metal layer 15 is more preferably 80 wt% or more, still more preferably 85 wt% or more, and particularly preferably 90 wt% or more, from the viewpoint of improving the visible light transmittance. For example, when the content of silver is 96 wt% or more, the wavelength selectivity of transmittance and reflectance can be improved, and the visible light transmittance can be improved. As the content of silver in the metal layers 514 and 554 increases, the visible light transmittance of the infrared-reflective film tends to increase.

On the other hand, silver may be deteriorated by oxidation, corrosion, and the like when exposed to an environment in which moisture, oxygen, chlorine, and the like exist, or when irradiated with ultraviolet light or visible light. Therefore, the metal layers 514, 554 are preferably silver alloy layers containing metals other than silver for the purpose of improving durability. For example, the metal layers 514 and 554 preferably contain 0.1 wt% or more, more preferably 0.2 wt% or more, and further preferably 0.3 wt% or more of a metal other than silver. As the metal that can be added for the purpose of improving the durability of the metal layer, palladium (Pd), gold (Au), copper (Cu), bismuth (Bi), germanium (Ge), gallium (Ga), and the like are preferable. Among them, Pd is most preferably used from the viewpoint of imparting high durability to silver. When the amount of Pd or the like added is increased, the durability of the metal layer tends to be improved. On the other hand, if the amount of Pd or the like added is too large, the visible light transmittance of the infrared reflective film tends to decrease. Therefore, the content of the metal other than silver in the metal layer is preferably 10 wt% or less, more preferably 5 wt% or less, further preferably 3 wt% or less, and particularly preferably 1 wt% or less.

The metal layer is not limited to silver alloys, and for example, gold alone or a gold alloy containing gold as a main component may be used from the viewpoint of improving durability. The gold content of the gold alloy is preferably 75 to 99.9 wt%. In particular, the content of gold in the metal layer is preferably 80 wt% or more, more preferably 85 wt% or more, and particularly preferably 90 wt% or more, from the viewpoint of improving the visible light transmittance. In addition, silver is preferably used as an impurity, and for example, silver is preferably contained in an amount of 1 to 25 wt%, more preferably 10 wt% or less, and further preferably 5 wt% or less.

The metal layer 1 514 and the metal layer 2 554 may be different metals, and for example, the metal layer 2 near the surface and requiring high durability may be made of a gold alloy, while the metal layer 1 may be made of an inexpensive silver alloy.

The thicknesses of the 1 st metal layer 514 and the 2 nd metal layer 554 may be appropriately set in consideration of the refractive index of the material and the like so that the metal layers function as half mirrors. The thickness of the metal layers 514, 554 is preferably 4nm to 25nm, more preferably 5nm to 20 nm.

As a method for forming the metal layers 514 and 554, a dry method such as a sputtering method, a vacuum deposition method, or an electron beam deposition method is preferable. Among these, a film formation method which can perform roll-to-roll film formation and is common to the metal oxide layer can be employed, and a sputtering method is preferable because of a high film formation rate.

< Metal oxide layer >

The metal oxide layers 512, 516, 552, and 556 are provided for the purpose of controlling the amount of visible light reflection at the interface with the metal layer, and achieving both high visible light transmittance and infrared reflectance. The metal oxide layer may also function as a protective layer for preventing deterioration of the metal layers 514 and 554. From the viewpoint of improving the wavelength selectivity of reflection and transmission in the infrared reflective layer, the refractive index of the metal oxide layer with respect to visible light is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more.

Examples of the material having the refractive index include oxides of metals such as titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), zinc (Zn), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), and tin (Sn), or composite oxides of these metals. In particular, in the present invention, as the material of the metal oxide layers 512, 516, 552, and 556, a composite metal oxide containing zinc oxide can be suitably used. In addition, since these metal oxide layers also have a function of protecting the metal layer, they are preferably amorphous. In the case where the metal oxide layer is an amorphous layer containing zinc oxide, the durability of the metal oxide layer itself can be improved, and the function as a protective layer for the metal layer is increased, so that the deterioration of the metal layer containing a silver alloy can be suppressed.

The content of zinc oxide in the metal oxide layers 512, 516, 552, and 556 is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and still more preferably 7 parts by weight or more, based on 100 parts by weight of the total amount of the metal oxides. When the content of zinc oxide is in the above range, the metal oxide layer tends to be an amorphous layer, and the durability tends to be improved. On the other hand, when the content of zinc oxide is too large, the durability tends to be lowered or the visible light transmittance tends to be lowered. Therefore, the content of zinc oxide in the metal oxide layers 512, 516, 552, 556 is preferably 60 parts by weight or less, more preferably 50 parts by weight or less, and still more preferably 40 parts by weight or less, based on 100 parts by weight of the total amount of the metal oxides.

As the zinc oxide-containing composite metal oxide, indium-zinc composite oxide (IZO), zinc-tin composite oxide (ZTO), indium-tin-zinc composite oxide (ITZO), and the like are preferable from the viewpoint of satisfying all of visible light transmittance, refractive index, and durability. These composite oxides may further contain metals such as Al and Ga, and oxides of these metals.

The thicknesses of the metal oxide layers 512, 516, 552, 556 may be appropriately set in consideration of the refractive index of the material, etc., in order to allow the infrared ray reflective layer to transmit visible light and selectively reflect near infrared rays. The thickness of the metal oxide layers 512, 516, 552, 556 can be adjusted, for example, within a range of 3nm to 80nm, preferably 3nm to 50nm, and more preferably 3 to 35 nm. The method for forming the metal oxide layer is not particularly limited, but it is preferably formed by a dry method such as a sputtering method, a vacuum deposition method, a CVD method, or an electron beam deposition method, similarly to the metal layer.

< transparent spacer layer >

The transparent spacer 530 functions as a spacer for changing an optical distance between the 1 st metal layer and the 2 nd metal layer by adjusting the thickness thereof. Among these, by adjusting optical characteristics such as transmittance and reflectance of light from the substrate side by changing the optical distance, an infrared reflective film having high transmittance/low reflectance at a wavelength of 600nm and low transmittance/high reflectance at a wavelength of 700nm can be obtained. Such optical characteristics can be determined depending on the refractive index of the transparent spacer layer, and the materials and film thicknesses of the metal layer and the metal oxide layer, and for example, the optical film thickness (product of the physical thickness and the refractive index) of the transparent spacer layer is preferably 70nm to 300nm, more preferably 80nm to 250nm, and still more preferably 90nm to 200 nm. That is, considering that the refractive index of the transparent spacer layer is generally in the range of 1.3 to 1.7, the physical thickness of the transparent spacer layer is, for example, preferably 40nm to 200nm, more preferably 50nm to 180nm, and still more preferably 60nm to 160 nm.

The infrared-reflective substrate 500 may be formed by sequentially forming layers including the transparent spacer layer 530 on the transparent film base 10, but may be formed by forming the 2 nd laminate 550 on a transparent film base (not shown) different from the transparent film base 10 by giving an adhesive function to the transparent spacer layer 530 and bonding the 1 st laminate 510 formed on the transparent film base 10 with the transparent spacer layer 530 interposed therebetween. This bonding method is superior to the method in which layers are sequentially formed, in adhesion between the transparent film substrate 10 and the metal oxide layers 512 and 556, and between the transparent spacer layer 530 and the metal oxide layers 516 and 552.

After the 1 st stacked body 510 is formed on the transparent film substrate 10, a resin solution is coated on the metal oxide layer 516, thereby forming the transparent spacer layer 530. To improve adhesion between the metal oxide layers 516, 552, an adhesive may be preferably used for the transparent spacer layer 530. As the adhesive, a polyurethane adhesive, a polyurea adhesive, a polyacrylate adhesive, a polyester adhesive, an epoxy adhesive, a silicone adhesive, or the like can be preferably used. The adhesive may be used in a mixture of 2 or more, or a two-component curing adhesive, a two-component solvent adhesive, or the like may be used.

The adhesive preferably has a crosslinking agent. The first laminate 510 and the second laminate 550 are laminated so as to face each other with a crosslinkable adhesive interposed therebetween, and then crosslinked by heating, UV irradiation, or the like, whereby the adhesiveness between the 2 nd and 3 rd metal oxides 516 and 552 can be improved. Examples of the crosslinking agent include polyfunctional vinyl compounds, epoxy crosslinking agents, isocyanate crosslinking agents, imine crosslinking agents, and peroxide crosslinking agents.

The first laminate 510 and the second laminate 550 may be bonded by any of the following methods: a wet lamination method in which the first laminate 510 and the second laminate 550 are bonded to each other immediately after an adhesive is applied to the infrared reflective layer; and a dry lamination method in which the adhesive is dried and then bonded. In the present invention, the adhesive layer formed as the transparent spacer layer 530 greatly affects optical characteristics such as wavelength selectivity of transmission/reflection of the infrared-reflective film. Therefore, it is preferable to perform bonding by a dry lamination method which can realize precise thickness adjustment of the adhesive layer. When the adhesive is bonded by a dry lamination method, a dry lamination adhesive can be used.

Examples of the dry laminating adhesive include a two-component curing adhesive, a two-component solvent adhesive, and a one-component solvent-free adhesive. As the two-component curing adhesive, acrylic is used, as the two-component solvent type adhesive, polyester/polyurethane, polyether/polyurethane, epoxy is used, and as the one-component solvent-free adhesive (moisture curing type), polyether/polyurethane, epoxy and the like are used.

The resin solution such as an adhesive can be applied by a known method such as various roll coating methods such as a gravure coating method, a roll-lick coating method, a reverse coating method, and a meyer bar coating method, a spray coating method, a curtain coating method, and a die lip coating method. The thickness of the transparent spacer layer can be adjusted to a desired range by adjusting the solid content concentration and the coating thickness of the resin solution.

After the solvent is dried as necessary, the first laminate 510 and the second laminate 550 are bonded so that the second metal oxide layer 516 and the third metal oxide layer 552 face each other. In the bonding, heating may be performed as needed. When a crosslinkable adhesive is used, it is preferable to perform crosslinking treatment by heating, UV irradiation, or the like after bonding.

In the infrared-reflective substrate 500 in which the first laminate 510 and the second laminate 550 are bonded to each other with the adhesive as the transparent spacer layer 530 interposed therebetween, the metal layer and the metal oxide layer are disposed between the 2 transparent film substrates, and the transparent substrate on which the 2 nd laminate is formed functions as a protective layer described later, and therefore, physical properties such as scratch resistance are excellent in durability. Further, since the metal oxide layer is directly provided on each of the 2 transparent films without interposing another resin layer therebetween, and the metal oxide layer is provided in contact with both surfaces of the metal layer, the penetration of moisture and the like can be suppressed. Therefore, the infrared reflective film of the present invention has high chemical durability, and can maintain high heat insulating properties and transparency without deterioration of the metal layer even when exposed to a high-temperature and high-humidity environment. Of course, the transparent film base located on the 4 th metal oxide layer is not essential, and therefore, the 1 st stacked body 510 and the 2 nd stacked body 550 may be removed after being bonded.

[ transparent protective layer ]

In the present invention, a transparent protective layer (not shown) is not essential, but a transparent protective layer may be provided on the second metal oxide layer of the infrared reflective layer for the purpose of preventing scratches and deterioration of the metal oxide layer and the metal layer. From the viewpoint of forming the transparent protective layer within the range of the heat-resistant temperature of the film base material, an organic substance may be used as the material of the transparent protective layer, but an inorganic substance may be used.

It is preferable that the transparent protective layer has a small absorption of far infrared rays in addition to a high transmittance of visible light. When the absorption rate of far infrared rays is high, the far infrared rays in the room are absorbed by the transparent protective layer and are radiated to the outside by heat conduction, and therefore, the heat insulation property of the infrared ray reflective film tends to be lowered. On the other hand, when the absorption of far infrared rays by the transparent protective layer is small, the far infrared rays are reflected toward the room through the metal layers 514 and 554 of the infrared reflective layer, and thus the heat insulating effect of the infrared reflective film is improved. As a method of reducing the amount of absorption of far infrared rays by the transparent protective layer, a method of reducing the thickness of the transparent protective layer, and a method of using a material having a low absorption rate of far infrared rays as a material of the transparent protective layer can be cited.

When the thickness of the transparent protective layer is adjusted to reduce the absorption of far infrared rays, the thickness of the transparent protective layer is preferably 300nm or less, more preferably 200nm or less, and still more preferably 100nm or less. When the thickness of the transparent protective layer is small, the heat insulating effect can be improved by reducing the amount of far infrared ray absorption, but on the other hand, the function as a protective layer for improving the durability of the infrared ray reflective layer may be reduced. Therefore, when the thickness of the transparent protective layer is 200nm or less, it is preferable to use a material having excellent strength as the transparent protective layer and also to improve the durability of the infrared reflective layer itself. As a method for improving the durability of the infrared reflective layer itself, there is a method of decreasing the content of silver in the metal layers 514 and 554 and increasing the content of components such as palladium. For example, when the metal layers 514 and 554 are an alloy of silver and palladium, the content of silver to palladium is preferably adjusted to about 96:4 to 98:2 by weight.

On the other hand, if a material having a small absorption rate of far infrared rays is used as the material of the transparent protective layer, the amount of far infrared rays absorbed can be kept small even if the thickness of the protective layer is increased, and therefore, the protective effect on the infrared ray reflective layer can be improved. According to this configuration, the durability of the infrared reflective film can be improved without excessively increasing the content of palladium or the like in the metal layers 514 and 554, and therefore, it is preferable to improve both the visible light transmittance and the durability. As a material of the transparent protective layer, a compound having a small content of a C ═ C bond, a C ═ O bond, a C — O bond, an aromatic ring, or the like can be suitably used from the viewpoint of reducing absorption of far infrared rays. As a material constituting the transparent protective layer, for example, polyolefin such as polyethylene and polypropylene, alicyclic polymer such as cyclic olefin polymer, rubber-based polymer, and the like can be suitably used.

As a material constituting the transparent protective layer, a material having a low far infrared ray absorption rate, a high visible light transmittance, excellent adhesion to the infrared ray reflective layer, and excellent scratch resistance can be suitably used. From this viewpoint, a rubber-based material is particularly preferable, and among them, a nitrile rubber-based material can be suitably used.

The method for forming the transparent protective layer is not particularly limited, and for example, the transparent protective layer can be formed by dissolving a polymer such as hydrogenated nitrile rubber in a solvent together with a crosslinking agent as necessary to prepare a solution, applying the solution on the infrared reflective layer 20, and then drying the solvent. The solvent is not particularly limited as long as it can dissolve the polymer, and a low boiling point solvent such as Methyl Ethyl Ketone (MEK) or methylene chloride can be suitably used. When a low boiling point solvent such as methyl ethyl ketone (boiling point: 79.5 ℃) or methylene chloride (boiling point: 40 ℃) is used as the solvent, the infrared reflective layer 20 can be coated with the solution and then dried at a low temperature, and therefore, thermal damage to the infrared reflective layer 20 and the transparent film substrate 10 can be suppressed. In the case where the 2 nd laminate 550 is formed on the transparent base material as described above and the 2 nd laminate 550 is bonded to the 1 st laminate 510 with the transparent spacer layer 530 formed of an adhesive interposed therebetween to form the infrared reflective substrate 500, the transparent base material may be made to have a thickness and a material suitable for the transparent protective layer and used as the transparent protective layer.

The material of the transparent protective layer may contain, in addition to the polymer, additives such as a coupling agent such as a silane coupling agent and a titanium coupling agent, a leveling agent, an ultraviolet absorber, an antioxidant, a heat stabilizer, a lubricant, a plasticizer, a coloring inhibitor, a flame retardant, and an antistatic agent. The content of these additives may be appropriately adjusted within a range not impairing the object of the present invention, but the content of the polymer in the transparent protective layer is preferably 80% by weight or more. For example, when hydrogenated nitrile rubber is used as the material of the transparent protective layer, the content of hydrogenated nitrile rubber in the transparent protective layer is preferably 90 wt% or more, more preferably 95 wt% or more, and still more preferably 99 wt% or more.

When a material having a low far infrared ray absorption rate, such as hydrogenated nitrile rubber, is used as the material of the transparent protective layer, the thickness of the transparent protective layer is preferably 1 to 20 μm, more preferably 2 to 15 μm, and still more preferably 3 to 10 μm. When the thickness of the transparent protective layer is within the above range, the protective layer itself has sufficient physical strength, and the protective function of the infrared reflective layer can be improved, and the amount of absorption of far infrared rays can be reduced.

[ other layers ]

As described above, the infrared-reflective substrate 500 of the present invention has the infrared-reflective layer composed of the 1 st metal oxide layer, the 1 st metal layer, the 2 nd metal oxide layer, the adhesive layer, the 3 rd metal oxide layer, the 2 nd metal layer, and the 4 th metal oxide layer on one principal surface of the transparent film base 10, but additional layers may be provided according to the usage situation. For the purpose of improving the adhesion of each layer, improving the strength of the infrared-reflective film, and the like, a hard coat layer, an easy-adhesion layer, and the like may be provided between the transparent film substrate 10 and the infrared-reflective layer 20, and between the infrared-reflective layer 20 and the transparent protective layer 30 when a transparent protective layer is disposed. The material and the forming method of the easy adhesion layer, the hard coat layer and the like are not particularly limited, and a transparent material having high visible light transmittance can be suitably used.

[ Properties of Infrared-reflective substrate including Infrared-reflective layer 500 ]

In the infrared-ray reflective layer 500, the refractive index (material) and thickness of each layer can be adjusted so that the transmittance of visible light having a wavelength of 600nm or less is 50% or more, preferably 55% or more, and more preferably 60% or more. The transmittance between 450nm and 550nm is particularly preferably 55% or more, more preferably 60% or more, still more preferably 65% or more, and most preferably 70% or more. In addition, the infrared reflective layer 500 can be adjusted in the type and thickness of the 2 nd and 3 rd metal oxide layers 516 and 552, the type and thickness of the transparent spacer layer 530, and the optical distance between the 1 st and 2 nd metal layers, so that the reflectance is improved from the wavelength of 600nm to the wavelength of 700 nm. In the infrared reflective layer 500, the slope of reflectance (dR) is between 600nm and 700nm_700-600(%/nm)) is 0.12 or more, preferably 0.15 or more, more preferably 0.20 or more, and still more preferably 0.25 or more.

< 3 layers of metal formation >

An infrared-reflective substrate 600 according to another embodiment of the present invention includes an infrared-reflective layer including 3 metal layers. Since the infrared reflection layer 600 includes 3 metal layers, complicated optical characteristics can be designed. The infrared-reflective substrate 600 shown in fig. 6 includes a base material and an infrared-reflective layer on the base material, and the infrared-reflective layer includes a 1 st metal oxide layer 612, a 1 st metal layer 614, a 2 nd metal oxide layer 616, a 2 nd metal layer 618, a 3 rd metal oxide layer 620, a 3 rd metal layer 622, and a 4 th metal oxide layer 624 in this order from the base material side. In addition, although the present embodiment includes 3 metal layers, the present invention may include 4 or more metal layers, and may alternately include metal layers and metal oxide layers as in the case of the configuration including 3 metal layers.

In the infrared reflective layer 600, the refractive index (material) and thickness of each layer can be adjusted so that the transmittance of visible light having a wavelength of 600nm or less is 50% or more, preferably 55% or more, and more preferably setIs more than 60 percent. The transmittance between 450nm and 550nm is particularly preferably 55% or more, more preferably 60% or more, still more preferably 65% or more, and most preferably 70% or more. In addition, the infrared reflective layer 600 may be adjusted in the type and thickness of each layer so that the reflectance increases from a wavelength of 600nm to a wavelength of 700 nm. In the infrared reflective layer 500, the slope of reflectance (dR) is between 600nm and 700nm_700-600(%/nm)) is 0.12 or more, preferably 0.15 or more, more preferably 0.20 or more, and still more preferably 0.25 or more.

As the metal layer and the metal oxide layer of the infrared-reflective substrate 600, metals and metal oxides described in relation to the infrared-reflective substrate 500 can be used. In addition, as in the infrared reflective substrate 500, an adhesive layer, a protective film, and a hard coat layer may be used as necessary.

< organic multilayer Structure >

An infrared-reflective substrate according to another embodiment of the present invention includes an infrared-reflective layer formed by combining a plurality of organic resins of 2 or more kinds. The infrared reflective substrate includes a base material and an infrared reflective layer on the base material, and the infrared reflective layer includes 2 kinds of organic resins having different refractive indices alternately. Specifically, the infrared reflective layer includes a plurality of 1 st type organic layers and a plurality of 2 nd type organic layers alternately, and includes a plurality of 2 types of resin laminates each having a thickness gradually reduced from the base material side. That is, the 2 nd organic layer has the same thickness as the 1 st organic layer located immediately below the 2 nd organic layer, and the plurality of 1 st organic layers and the plurality of 2 nd organic layers are gradually thinned from the substrate side. In the infrared reflective layer of the present embodiment, the 2 nd type organic layer having the same thickness is formed on the main surface of the 1 st type organic layer, the 1 st type organic layer having a certain thickness reduced is formed thereon, and the 2 nd type organic layer having the same thickness is further formed thereon, and the above operations are repeated to form the 2 type resin laminate. Further, the 2 kinds of resin laminates were stacked in a plurality of layers to form an infrared-reflective substrate.

By defining the material of the 1 st and 2 nd organic layers and the thickness of each layer, the thickness of the organic layer can be reduced to 600nm or lessThe transmittance of visible light of the lower wavelength is 50% or more, preferably 55% or more, and more preferably 60% or more. The transmittance between 450nm and 550nm is preferably 55% or more, more preferably 60% or more, still more preferably 65% or more, and most preferably 70% or more. The reflectance increases from 600nm to the long wavelength side. In the infrared reflective layer 500, the slope of reflectance (dR) is between 600nm and 700nm_700-600(%/nm)) is 0.12 or more, preferably 0.15 or more, more preferably 0.20 or more, and still more preferably 0.25 or more.

The thickness of the 2 kinds of resin laminates varies depending on the desired optical characteristics and the material used, but for example, the thickest layer is preferably 180nm to 240nm, more preferably 190nm to 230nm, and still more preferably 200nm to 220 nm. The thinnest layer is preferably 120nm to 180nm, more preferably 130nm to 170nm, and still more preferably 140nm to 160 nm. The variation in thickness of the 1 st and 2 nd organic layers is preferably 1nm to 20nm, more preferably 2nm to 10nm, and still more preferably 3nm to 7 nm. The number of layers of the 1 st resin layer and the 2 nd resin layer in each of the 2 resin laminates is preferably 5 to 30, more preferably 8 to 20, and still more preferably 10 to 15. The number of 2 resin laminates included in the infrared-reflective substrate is preferably 10 or more, but the spectrum of the refractive index and the transmittance can be more precisely defined by increasing the number of layers, and therefore, the infrared-reflective substrate preferably includes 15 or more layers, and more preferably 20 or more layers. Of course, from the viewpoint of reducing the number of steps for producing the infrared-reflective substrate, the number of layers is preferably 35 or less, and more preferably 25 or less.

As the material that can be used for the 1 st and 2 nd organic layers, any 2 kinds of organic materials having different refractive indices may be used. For example, the refractive index is preferably 1.3 to 1.7, and more preferably 1.4 to 1.6. The difference in refractive index between the 2 kinds of organic substances is preferably 0.01 to 0.2, more preferably 0.03 to 0.1. For example, polyester resin and polyurethane resin can be used. As a material usable as the polyester resin, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene 2, 6-naphthalate, poly (1, 4-cyclohexanedimethanol terephthalate), polyethylene terephthalate (polyethylene terephthalate), and the like are typical. Particularly, polyethylene terephthalate is preferred because it is inexpensive and can be used in a very wide range of applications. Further, the preferred amorphous polyester resin has a structure obtained by polycondensation using at least 3 or more kinds of dicarboxylic acid components and diol components in total. The amorphous polyester resin may be a mixture of 2 or more polyester resins, as long as it is amorphous.