JP2018173608A - Heat ray shielding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat ray shielding member that can reduce a change in hue due to the incident angle of light or the angle at which the heat ray shielding member is visually recognized.SOLUTION: A heat ray shielding member comprises: a transparent substrate; a heat ray reflection layer that is provided with at least two selective reflection layers having cholesteric liquid crystal reflecting an infrared ray; and a heat ray absorption layer that absorbs an infrared ray, where the heat ray shielding member has a sunlight total transmittance of 41% or more and 70% or less and a visible light transmittance of 70% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat ray shielding member that reflects infrared rays that exhibits an excellent heat insulation effect and can suppress a change in color depending on the incident angle of light and the position of a viewpoint.

  It is required to reduce the impact on the environment by suppressing the reduction of cooling efficiency in automobiles and trains and in the building interior, improving energy efficiency and improving fuel efficiency, and high standards of heat insulation are required. It is coming. Therefore, a heat ray shielding member that selectively reflects electromagnetic waves (light) having a wavelength in the infrared region is applied to the window glass of a building and the glass of a car window.

  As such a heat ray shielding member, there is a technique using a cholesteric liquid crystal capable of selectively reflecting light having a desired wavelength in the infrared wavelength region (for example, Patent Document 1). As a result, only light having a desired wavelength can be selectively reflected, so that, for example, visible rays are transmitted to maintain external visibility, and only heat rays (infrared rays) are reflected to improve heat insulation. .

JP 2009-227938 A

  However, in a heat ray shielding member including a member using a cholesteric liquid crystal as in Patent Document 1, when light is incident on the member from an oblique direction or an observer views the member from an oblique direction, the incident from the front is performed. The color of the member may appear to change with light and observation from the front. In addition, when the opposite side is viewed through the member, the object on the opposite side may appear a different color from the actual color.

  Then, this invention makes it a subject to provide the heat ray shielding member which can suppress a color change also with the incident angle of light, or the angle to visually recognize in view of the above-mentioned problem.

  One aspect of the present invention is a heat ray shielding member that reflects infrared rays, a heat ray reflective layer that includes a transparent substrate, and at least two selective reflection layers each having a cholesteric liquid crystal that reflects infrared rays, and an infrared ray A heat ray absorbing layer that absorbs water, and has a total solar transmittance of 41% to 70% and a visible light transmittance of 70% or more.

  In the above-mentioned heat ray shielding member, when light is incident from a chromaticity a * of transmitted light when light is incident from a direction inclined by 55 ° with respect to the normal line of the surface of the heat ray shielding member, and from a direction inclined by 5 ° The difference between the chromaticity a * of the transmitted light and the chromaticity b * of the transmitted light when the light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member is 3.0 or less. And the chromaticity b * of the transmitted light when light is incident from a direction inclined by 5 ° can be configured to be 3.0 or less.

  Furthermore, in the heat ray shielding member, when the light is incident from the chromaticity a * of the reflected light when the light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member, and from the direction inclined by 5 ° The difference between the chromaticity a * of the reflected light is 6.4 or less and the chromaticity b * of the reflected light when light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member Also, the difference between the chromaticity b * of reflected light when light is incident from a direction inclined by 5 ° can be configured to be 6.4 or less.

  One of the selective reflection layers is a layer including a cholesteric liquid crystal having a center wavelength of reflection of 834 nm or more and a right-handed spiral structure, and the other one of the selective reflection layers is left-turned with a center wavelength of reflection of 834 nm or more. A layer containing a cholesteric liquid crystal having a spiral structure of

One of the selective reflection layers may be a layer including a cholesteric liquid crystal having a reflection central wavelength of 834 nm or more, and the other of the selective reflection layers may be a layer including a cholesteric liquid crystal having a different reflection central wavelength.
At this time, the turning direction of the spiral structure of one selective reflection layer and the turning direction of the spiral structure of another selective reflection layer may be the same or opposite. Here, when the turning directions are the same, the center wavelength is preferably different by 50 nm or more.

  It can also be set as the structure by which the heat ray reflective layer is laminated | stacked on the one surface of the transparent substrate by the contact bonding layer. Further, the adhesive layer may include a heat ray absorbent, and the adhesive layer may also serve as the heat ray absorbing layer.

  In the above, the cholesteric liquid crystal may be composed of a chiral nematic liquid crystal obtained by mixing a nematic liquid crystal with a chiral agent.

  Further, the nematic liquid crystal and the chiral agent each have a functional group capable of crosslinking, and the cholesteric structure can be fixed by crosslinking these functional groups.

  Further, at least one of the nematic liquid crystal and the chiral agent may be a compound having an acrylate structure.

  You may comprise so that the heat ray absorption layer contained in the said heat ray shielding member contains resin and the inorganic near-infrared absorber with an average particle diameter of 40 nm-200 nm, and an inorganic near-infrared absorber is a tungsten oxide type compound.

In addition, the tungsten oxide compound includes at least one element selected from the group consisting of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn, W as tungsten, O as oxygen, When 0.001 ≦ x / y ≦ 1.1 and 2.2 ≦ z / y ≦ 3.0,
MxWyOz
It may be expressed as

  The tungsten oxide compound may be cesium-containing tungsten oxide.

  According to the present invention, an excellent heat insulating effect can be obtained, and color change due to obliquely incident light and a viewing angle can be suppressed.

2 is a diagram illustrating a layer configuration of a heat ray shielding member 10. FIG. It is the figure showing the radiant energy intensity of the sunlight in the ground surface for every wavelength. It is a figure showing the permeation | transmission characteristic of light and the reflective characteristic of light which concern on one example. It is a figure showing the permeation | transmission characteristic of light and the reflection characteristic of light which concern on another example. It is a figure explaining the effect when the heat ray shielding member 10 is used. It is a figure explaining the layer structure of the heat ray shielding member 20, 20 '. It is a figure explaining the layer structure of the transfer sheets 30 and 30 '. It is a figure explaining the layer structure of the heat ray shielding member.

  Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings. However, the present invention is not limited to the embodiments described here. In the drawings, for easy understanding, the shape such as the layer thickness may be shown large or deformed.

  FIG. 1 shows the layer configuration of the heat ray shielding member 10 according to the first embodiment. As can be seen from FIG. 1, the heat ray shielding member 10 is a thin plate-like member as a whole, and a plurality of layers are laminated. Specifically, in the heat ray shielding member 10 of this embodiment, the transparent substrate 11, the heat ray reflective layer 12 arranged on one surface of the transparent substrate 11, and the heat ray reflective layer 12 among the surfaces of the transparent substrate 11 are arranged. The heat ray absorbing layer 13 is laminated on the surface opposite to the opposite side. Each layer will be described below.

  The transparent substrate 11 is a substrate that is transparent and supports the heat ray reflective layer 12 and the heat ray absorbing layer 13, and the material thereof is not particularly limited. However, from the viewpoint of the application of the heat ray shielding member 10, it is preferable that the transmittance in the visible light region is high. Specifically, the transmittance is preferably 80% or more, more preferably 90% or more. The transmittance of the transparent substrate can be measured according to JIS K7361-1 (Plastic—Testing method for the total light transmittance of a transparent material).

  The transparent substrate 11 may have flexibility or may not have flexibility. Examples of such transparent substrates include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, olefin resins such as polyethylene and polymethylpentene, acrylic resins, polyurethane resins, polyethersulfone, polycarbonate, polysulfone, Examples thereof include those made of resins such as polyether, polyether ketone, (meth) acrylonitrile, cycloolefin polymer, cycloolefin copolymer, and polyvinyl butyral (PVB). Among them, it is preferable to use a transparent substrate made of polyethylene terephthalate from the viewpoint of versatility and availability. In addition, when polyvinyl butyral is used, when the heat ray shielding member is placed between the laminated glasses, it has excellent integrity with the polyvinyl brachial interlayer used as an adhesive, reducing problems such as wrinkles and rainbow unevenness. Thus, the appearance and adhesion are improved.

  A transparent substrate having liquid crystal orientation can also be used. Thereby, the orientation of the liquid crystal contained in the heat ray reflective layer 12 can be enhanced. Examples of the transparent substrate having orientation include a stretched polymer film, and specifically, a stretched film made of a polyester resin such as polyethylene terephthalate can be suitably used.

  About the thickness of a transparent substrate, it can determine suitably according to the material etc. which comprise the use of a heat ray shielding member, and a transparent substrate.

  The heat ray reflective layer 12 contains a rod-shaped compound that forms a cholesteric structure, and is formed by laminating at least two selective reflective layers that reflect infrared rays. The heat ray reflective layer 12 of this embodiment includes two selective reflective layers 12a and 12b. However, the present invention is not limited to this, and two or more selective reflection layers may be provided.

And the selective reflection wavelength in the selective reflection layer included in the heat ray reflective layer of this embodiment has a center wavelength of 834 nm or more. A preferred center wavelength is 844 nm or more, more preferably 854 nm or more. Here, the “center wavelength” is a wavelength that is an average value of wavelengths that are half the reflection intensity at the peak wavelength of the selective reflection wavelength.
Thereby, the infrared rays, which are heat rays having a heating action, are reflected to have a high heat insulating effect. In addition, even when light is incident obliquely on a member (for example, a glass window) provided with a heat ray shielding member, and even when an observer views the member from an oblique direction, the light from the front The change in color with respect to incidence and observation from the front can be kept small.
Here, since the center wavelength of selective reflection in the selective reflection layer corresponds to the pitch of the cholesteric structure in the cholesteric liquid crystal, it can be realized by adjusting the pitch.

Here, the selective reflection layer 12a and the selective reflection layer 12b of this embodiment both have the same selective reflection center wavelength, but are configured to have different spiral turning directions of the cholesteric structure. For example, the selective reflection layer 12a has a clockwise spiral structure, and the selective reflection layer 12b has a counterclockwise spiral structure.
As a result, light having a predetermined wavelength can be reflected at a high rate (for example, 70% or more) regardless of the polarization state of incident light. In order to give the cholesteric structure a turning property in a desired direction, for example, it is possible to select the kind of the chiral agent to be contained.

The rod-like compound constituting the cholesteric liquid crystal is not particularly limited as long as it can form a cholesteric structure in the selective reflection layer, but usually has a refractive index anisotropy and is contained in the molecule. Those having a polymerizable functional group are preferably used. Further, those having a polymerizable functional group capable of three-dimensional crosslinking are more preferred. Since the rod-shaped compound has a polymerizable functional group, it is possible to polymerize and fix the rod-shaped compound, and thus it is possible to make it difficult to change with time. Moreover, you may use it, mixing the rod-shaped compound which has a polymerizable functional group, and the rod-shaped compound which does not have a polymerizable functional group.
Note that “three-dimensional crosslinking” means that rod-like compounds are polymerized three-dimensionally to form a network (network) structure.

  Here, examples of the polymerizable functional group include polymerizable functional groups that are polymerized by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat. Representative examples of these polymerizable functional groups include radically polymerizable functional groups or cationic polymerizable functional groups. Further, representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and specific examples include vinyl groups having or not having substituents, An acrylate group (generic name including an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group) and the like can be given. Moreover, an epoxy group etc. are mentioned as a specific example of the said cation polymerizable functional group. In addition, examples of the polymerizable functional group include an isocyanate group and an unsaturated triple bond. Among these, from the viewpoint of the process, a functional group having an ethylenically unsaturated double bond is preferably used.

  Further, the rod-like compound is preferably a liquid crystalline material exhibiting liquid crystallinity, and particularly preferably a nematic liquid crystalline material. Specific examples of the rod-like compound include compounds represented by the following chemical formulas (1) to (6).

  Here, the liquid crystalline materials represented by the chemical formulas (1), (2), (5) and (6) are disclosed in DJ Broer et al., Makromol. Chem. 190,3201-3215 (1989), or DJ Broer et al., Makromol. Chem. 190,2255-2268 (1989), or can be prepared similarly. The preparation of liquid crystalline materials represented by the chemical formulas (3) and (4) is disclosed in DE 195,04,224.

  Specific examples of the nematic liquid crystalline material having an acrylate group at the terminal include those represented by the following chemical formulas (7) to (17).

  Furthermore, examples of the rod-like compound include a compound represented by the following chemical formula (18) disclosed in SID 06 DIGEST 1673-1676.

  In addition, a rod-shaped compound may use only 1 type, or may mix and use 2 or more types. For example, as a rod-shaped compound, a liquid crystalline material having one or more polymerizable functional groups at both ends and a liquid crystalline material having one or more polymerizable functional groups at one end may be mixed and used. Thereby, a polymerization density (crosslinking density) and an optical characteristic can be arbitrarily adjusted by adjustment of the compounding ratio of both.

  The selective reflection layer may contain a chiral agent in order to form a cholesteric structure of a rod-like compound. By containing the chiral agent, the chiral nematic crystal can be immobilized. Moreover, as above-mentioned, a chiral agent can be selected from a viewpoint of providing turning property in a desired direction.

  The chiral agent is not particularly limited as long as the rod-shaped compound can be arranged in a predetermined cholesteric arrangement. For this, for example, it is preferable to use a low molecular compound having axial asymmetry in the molecule as represented by the following general formula (19), (20) or (21).

In the general formula (19) or (20), R ¹ represents hydrogen or a methyl group. Y is any one of formulas (i) to (xxiv) shown above, and among them, any one of formulas (i), (ii), (iii), (v), and (vii) Preferably there is. Moreover, although c and d which show the chain length of an alkylene group can each take arbitrary integers in the range of 2-12, it is preferable that it is the range of 4-10, and is the range of 6-9. Is more preferable.

  Moreover, what is represented by the following chemical formula can also be used as a chiral agent.

  As content of a chiral agent, it is preferable that it is normally in the range of 1.0 mass%-10.0 mass% normally with respect to the sum total of a rod-shaped compound and a chiral agent, and 2.0 mass%-4. especially. More preferably, it is in the range of 0% by mass. This is because the wavelength of light reflected by the selective reflection layer can be adjusted by setting the content of the chiral agent in the above range.

  The thickness of each selective reflection layer is not particularly limited as long as it is within a range in which a desired wavelength selective reflection function can be imparted to the selective reflection layer. For this reason, the thickness of the selective reflection layer is usually preferably in the range of 0.1 μm to 100 μm, more preferably in the range of 0.5 μm to 20 μm, and in the range of 1 μm to 10 μm. More preferably.

  The heat ray absorbing layer 13 is laminated on the surface of the transparent substrate 11 opposite to the side where the heat ray reflecting layer 12 is disposed, and has a function of absorbing infrared rays. Thereby, a heat ray can be interrupted | blocked more reliably and heat insulation can be improved.

Such a heat ray absorbing layer 13 is formed, for example, by forming a layer containing an infrared absorber on a film substrate such as a polyester resin by a coating method or the like, or by adding an infrared absorber to a material to be a transparent substrate. Can be mentioned. Examples of the resin that becomes the transparent substrate include acrylic resins and polyester resins.
Examples of infrared absorbers include cesium tungsten oxide, diimmonium compounds, phthalocyanine compounds, and the like.

A more preferred embodiment for the infrared absorber is as follows.
The inorganic near-infrared absorber is preferably an inorganic material having an average particle size of 40 nm or more and 200 nm or less from the viewpoints of compatibility between visible light transparency and near-infrared absorptivity, suitability for dispersion in a resin, and the like. Inorganic materials include metal oxides, metal borides, metal nitrides, and the like.
Examples of the metal oxide include tungsten oxide compounds, titanium oxide, zirconium oxide, tantalum oxide, niobium oxide, zinc oxide, ruthenium oxide, indium oxide, tin-doped indium oxide (ITO), tin oxide, and antimony-doped tin oxide ( ATO), cesium oxide and the like.
As the metal boride (boride), a metal boride compound is preferable. Specifically, lanthanum boride (LaB ₆ ), praseodymium boride (PrB ₆ ), neodymium boride (NdB ₆ ), cerium boride ( CeB ₆ ), yttrium boride (YB ₆ ), titanium boride (TiB ₆ ), zirconium boride (ZrB ₆ ), hafnium boride (HfB ₆ ), vanadium boride (VB ₆ ), tantalum boride (TaB ₆₎ ), Chromium boride (CrB, CrB ₆ ), molybdenum boride (MoB ₆ , Mo ₂ B ₅ , MoB), tungsten boride (W ₂ B ₅ ), and the like.
Examples of the metal nitride include titanium nitride, niobium nitride, tantalum nitride, zirconium nitride, hafnium nitride, and vanadium nitride.

Among these, a tungsten oxide compound is preferable because it has a high near-infrared absorptivity and a high visible light transmittance, and a tungsten oxide compound represented by the following general formula is particularly preferable.
MxWyOz
Here, the M element is at least one selected from the group consisting of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn, W represents tungsten, and O represents oxygen. . Among these tungsten oxide compounds, cesium-containing tungsten oxide in which the M element is represented by Cs is particularly preferable because of its high near-infrared absorbing ability.

Further, the amount of M element added here preferably satisfies the relationship of 0.001 ≦ x / y ≦ 1.1 as the value of x / y based on the content of tungsten, and in particular x / Y is preferably in the vicinity of 0.33 in that it exhibits a suitable near infrared absorption ability. Further, when x / y is around 0.33, a hexagonal crystal structure is easily obtained, and the use of this crystal structure is also preferable in terms of durability.
Further, the oxygen content preferably satisfies the relationship of 2.2 ≦ z / y ≦ 3.0 as the value of z / y based on the content of tungsten. More specifically, Cs _0.33 WO ₃ , Rb _0.33 WO ₃ , K _0.33 WO ₃ , Ba _0.33 WO _{3 and the} like can be mentioned.

The inorganic near-infrared absorber preferably has an average particle size of 40 nm to 200 nm. If the average particle size is less than 40 nm, the near-infrared absorption ability may be insufficient. If the average particle size exceeds 200 nm, white turbidity may occur due to Mie scattering, and the contrast may be lowered. In order to exhibit more preferable near-infrared absorption performance, the average particle diameter is more preferably 40 nm or more and 80 nm or less, and further preferably 40 nm or more and 60 nm or less.
In addition, the measurement of an average particle diameter is image | photographed with a transmission electron microscope, for example, extracts 50 inorganic near-infrared absorbers at random, measures this particle diameter, and averages this. Moreover, when the shape of particle | grains is not spherical, it defines as what was calculated by measuring a major axis.

The content of the near-infrared absorber in the heat ray absorbing layer is preferably in the range of 0.01 g / m ² or more and 10 g / m ² or less in terms of content per unit area. If the content is 0.01 g / m ² or more, a sufficient near-infrared absorption effect appears, and if it is 10 g / m ² or less, a sufficient amount of visible light can be transmitted.

  The heat ray shielding member 10 described above may further have a functional layer. Examples thereof include an ultraviolet absorbing layer, a heat insulating layer, a low radiation layer, and an alignment film.

The ultraviolet absorbing layer is not particularly limited, but for example, a film formed by adding an ultraviolet absorber having a benzotriazole-based compound, a benzophenone-based compound, a salicylate-based compound, or the like into a film such as a polyester resin or an acrylic resin. Can be mentioned.
The position where such an ultraviolet absorbing layer is formed is not particularly limited as long as it does not inhibit the reflection of infrared rays by the heat ray reflective layer 12, and for example, a position that is an outer layer than the selective reflection layer 12b. It is preferable that Thereby, deterioration by the ultraviolet-ray of another layer can be suppressed.

The heat insulating layer is a layer having a function of preventing heat conduction from the outside to the inside or from the inside to the outside via the heat ray shielding member. Examples of the material for forming such a heat insulating layer include materials that can contain air, such as porous materials, hollow silica, nano hollow particles made of silica shells, and the like.
The position where the heat insulating layer is formed is preferably a position that does not become the outside light side from the selective reflection layer when the heat ray shielding member is used. This is because when the selective reflection layer reflects infrared rays through the heat insulating layer, the reflection efficiency is not improved.

The heat ray reflective layer 12 may include an alignment film. Thereby, the rod-shaped liquid crystal compound in the selective reflection layer can be stably aligned in a predetermined direction.
As the alignment film, a known alignment film can be used, and examples thereof include polyamide resin, polyimide resin, polyvinyl alcohol resin, hydroxyethyl cellulose, polycarbonate resin, polystyrene resin, polymethyl methacrylate resin, and polyester resin. Further, the alignment film formed using these resins may be subjected to a rubbing treatment or the like. The alignment film may be formed by bonding a stretched resin sheet or the like to a substrate or the like.
Further, by using a transparent substrate having an orientation as described above, it can also function as an alignment film.

The heat ray shielding member 10 as described above operates as follows.
FIG. 2 shows the distribution of average solar radiation energy (Wm ⁻² / nm) on the ground surface in the temperate zone. In this figure, the horizontal axis indicates the wavelength and the vertical axis indicates the radiation energy, and the radiation energy for each wavelength on the ground surface appears. Here, a wavelength of 380 nm or more and 750 nm or less is a visible light region, and is visually recognized as a color. A wavelength exceeding 750 nm and not more than 2500 nm is the infrared region. As can be seen from FIG. 2, since the intensity of sunlight changes depending on the wavelength, heat rays (infrared rays) can be more effectively shielded by selectively reflecting a higher intensity wavelength region with a cholesteric liquid crystal. .

FIG. 3 shows a case where the heat ray shielding member 10 is irradiated with light from a direction inclined by θ ₁ = 5 ° with respect to the normal n direction of the surface of the heat ray shielding member 10 as indicated by L1 in FIG. The light reflectance% (FIG. 3A) and the light transmittance% (FIG. 3B) are shown respectively.
In this example, the central wavelength of selective reflection of the selective reflection layers 12a and 12b was set to 900 nm, and a deuterium lamp and a halogen lamp were switched at a wavelength of 340 nm as the light source of the irradiated light.

As can be seen from FIGS. 3 (a) and 3 (b), the light having the central wavelength of selective reflection of 900 nm and the light of the surrounding wavelength are reflected and are not transmitted to the opposite side. It becomes possible to block part of the infrared light that causes heating as a basic function of the apparatus 10. Thereby, combined with the action of the infrared absorption layer 13, the total sunlight transmittance can be 41% or more and 70% or less, and the visible light transmittance can be 70% or more. Here, the total sunlight transmittance is based on ISO 13837, and the visible light transmittance is based on ISO 9050.
And the reflection of the light at the time of irradiating light from the normal direction of the surface of the heat ray shielding member 10 is in the infrared region, and does not affect the visible light region of the transmitted light. Therefore, no color change is felt on the side opposite to the light incident side (transmitted light).

Further, in FIG. 4, when the heat ray shielding member 10 is irradiated with light from a direction inclined by θ ₂ = 55 ° with respect to the normal direction of the surface of the heat ray shielding member 10 as indicated by L2 in FIG. The light reflectance% (FIG. 4A) and the light transmittance% (FIG. 4B) are respectively shown. The characteristics of the incident light are the same as described above.

As can be seen from FIGS. 4A and 4B, in this case, the center wavelength of selective reflection is shifted to the short wavelength side. Therefore, it can be seen that the transmittance (transmitted light) is also shifted to the short wavelength side as compared with FIG. However, according to the heat ray shielding member 10, even when light is incident from an oblique direction as described above, most of the range in which the reflectance of light is high is in the infrared region. Since there is no change in color, there is almost no color change. Therefore, even if light is incident obliquely as described above, no color change is felt on the opposite side.
This is the same when the light from the normal n direction of the heat ray shielding member 10 is incident and observed from a position inclined by θ ₂ = 55 ° with respect to the normal as indicated by O3 in FIG. It is.
In this case as well, since light is reflected in the infrared region and is not transmitted to the opposite side, infrared rays that cause heating as a basic function of the heat ray shielding member 10 can be blocked.

  In this embodiment, by setting the center wavelength to 834 nm or more, it is possible to make it difficult to perceive a color change depending on the viewing angle, and it is also possible to block infrared rays.

The specific aspect regarding not feeling such a color change is as follows. That is, when the reflected light and transmitted light are expressed in the L * a * b * color system, the chromaticity a of transmitted light of light incident from a direction inclined by 55 ° with respect to the normal direction of the heat ray shielding member 10 The absolute value of the difference between * and the chromaticity a * of transmitted light incident from a direction inclined by 5 ° with respect to the normal direction of the heat ray shielding member 10 is 3.0 or less. Chromaticity b * of transmitted light incident from a direction inclined by 55 ° with respect to the normal direction, and transmitted light color of light incident from a direction inclined by 5 ° with respect to the normal direction of the heat ray shielding member 10 The absolute value of the difference from the degree b * is preferably 3.0 or less.
In addition to this, with respect to the reflected light that is substantially complementary to the transmitted light, the chromaticity a * of the reflected light incident from a direction inclined by 55 ° with respect to the normal direction of the heat ray shielding member 10 and the heat ray shielding The absolute value of the difference from the chromaticity a * of the reflected light incident from a direction inclined by 5 ° with respect to the normal direction of the member 10 is 6.4 or less, and the normal direction of the heat ray shielding member 10 The chromaticity b * of the reflected light incident from the direction inclined by 55 ° and the chromaticity b * of the reflected light incident from the direction inclined by 5 ° with respect to the normal direction of the heat ray shielding member 10 More preferably, the absolute value of the difference is 6.4 or less.

  As described above, according to the heat ray shielding member 10, while reflecting and blocking heat rays, there is no change in color even when irradiated with light from an oblique direction or observed from an oblique direction. The outside can be observed.

  As a use of the heat ray shielding member 10 as described above, it is possible to efficiently reflect heat rays (infrared rays) contained in sunlight, and to suppress color change due to the incident angle of sunlight and the viewpoint position of the observer. Therefore, it can be applied as a window glass. Specifically, for example, a windshield facing a driver's seat of a vehicle, a window glass of a building, and the like.

For example, assuming that the heat ray shielding member 10 is used for the windshield 1 of a passenger car, the windshield 1 is installed so as to be inclined with respect to the horizontal direction as schematically shown in FIG. There are many. Then, the sunlight S is incident on the windshield 1 at an angle close to the normal direction of the windshield 1, but the observer O who is a driver views the windshield 1 from an oblique direction. Even in such a case, since the heat ray shielding member 10 is used, the outside can be observed with an appropriate color without feeling a color change while reflecting and absorbing the heat ray and blocking it. .
Further, assuming that the heat ray shielding member 10 is used for the window glass 2 of the building or the windshield of the bus, the window glass 2 is installed so as to stand vertically as schematically shown in FIG. There are many. Then, the line of sight of the observer O is in the normal direction of the window glass 2, but sunlight S enters the window glass 2 from a direction inclined with respect to the normal direction of the window glass 2. Even in such a case, since the heat ray shielding member 10 is used, the outside can be observed with an appropriate color without reflecting a color change while reflecting and blocking the heat ray.

  Next, the second embodiment will be described. The heat ray shielding member of the second embodiment has the same layer configuration as that of the heat ray shielding member 10, but the features of the selective reflection layer 12a and the selective reflection layer 12b included in the heat ray reflection layer 12 are different. Therefore, here, the characteristics of the selective reflection layer 12a and the selective reflection layer 12b in the second embodiment will be described.

Among the plurality of selective reflection layers 12a and 12b included in the heat ray reflective layer 12 provided in the second embodiment, the selective reflection wavelength W1 of one selective reflection layer 12a has a center wavelength of 834 nm or more. A preferred center wavelength is 844 nm or more, more preferably 854 nm or more.
The selective reflection wavelength W2 of another selective reflection layer 12b different from the single selective reflection layer 12a has a wavelength different from the selective reflection wavelength W1 of the selective reflection layer 12a. The preferable difference between the selective reflection wavelength W1 and the selective reflection wavelength W2 is that the selective reflection layer 12a and the selective reflection layer 12b have the same or opposite turning directions in the spiral structure of the cholesteric liquid crystal. Will be explained later.
Thus, by making the selective reflection wavelength W1 of the selective reflection layer 12a different from the selective reflection wavelength W2 of the selective reflection layer 12b, the reflectance of each selective reflection wavelength is 50% or less. Infrared light can be reflected at a wider wavelength than when the reflection wavelength is the same. Therefore, this also reflects infrared rays, which are heat rays having a heating action, and has a high heat insulating effect. In addition, even when light is incident obliquely on a member (for example, a glass window) provided with a heat ray shielding member, and even when an observer views the member from an oblique direction, the light from the front The change in color with respect to incidence and observation from the front can be kept small.
Here, since the center wavelength of selective reflection in the selective reflection layer corresponds to the pitch of the cholesteric structure in the cholesteric liquid crystal, it can be realized by adjusting the pitch.

Here, in the selective reflection layer 12a and the selective reflection layer 12b in the second embodiment, each has a different center wavelength of selective reflection, but the swirl directions of the spirals of the cholesteric structure are different even if they are the same. May be.
When both turning directions are the same, the difference between the central wavelengths of selective reflection (the absolute value of the difference between W1 and W2) is preferably 50 nm or more, and more preferably 100 nm or more. If both swirl directions are the same, if there is an overlapping part in the wavelengths reflected at the peripheral wavelengths other than the central wavelength, it is not possible to reflect light with the opposite swivel direction even in that part. Therefore, it is preferable to take a large difference in the center wavelength of selective reflection.
On the other hand, when the turning directions of the two are opposite, the difference in the center wavelength of selective reflection (the absolute value of the difference between W1 and W2) is preferably 50 nm or less, more preferably 30 nm or less. When the turning directions of the two are different, even if there is a portion overlapping with the wavelength reflected at the peripheral wavelength other than the center wavelength, the light in both the turning directions can be reflected, so that it can be reflected without waste.

  Also by such a heat ray shielding member. While exhibiting the outstanding heat insulation effect, the change of the color by the incidence of the light from diagonally and the angle to visually recognize can be suppressed.

Next, a third embodiment will be described. FIG. 6A shows a layer configuration of the heat ray shielding member 20 of the third embodiment, and FIG. 6B shows a layer configuration of the heat ray shielding member 20 ′ of the modification. In the heat ray shielding member 20, an adhesive layer 21 is provided between the transparent substrate 11 and the heat ray reflective layer 12 in the heat ray shielding member 10. Further, in the heat ray shielding member 20 ′, the heat ray absorbing layer 13 and the heat ray reflecting layer 12 are laminated on one side of the transparent substrate 11, and the adhesive layer 21 is provided between the transparent substrate 11 and the heat ray absorbing layer 13.
Such heat ray shielding members 20 and 20 ′ also have the same effect as the heat ray shielding member 10. Further, the heat ray shielding members 20, 20 ′ can be produced by transfer.

  Here, the adhesive layer 21 may be appropriately selected as a pressure-sensitive adhesive or an adhesive from among conventionally known pressure-sensitive adhesives (pressure-sensitive adhesives), two-component curable adhesives, UV-curable adhesives (viscous). Adhesives), thermosetting adhesives, hot melt adhesives, and the like can be suitably used. Among these, it is preferable to use an ultraviolet curable adhesive or an ultraviolet curable adhesive.

  A method of manufacturing the heat ray shielding members 20 and 20 'by transfer will be described. FIG. 7A shows the layer configuration of the transfer sheet 30 used for transfer on the heat ray shielding member 20, and FIG. 7B shows the layer configuration of the transfer sheet 30 ′ used for transfer on the heat ray shielding member 20 ′. expressed.

As can be seen from FIG. 7A, the transfer sheet 30 is configured to include the support base material 31 and the heat ray reflective layer 12. Further, as can be seen from FIG. 7B, the transfer sheet 30 ′ includes the support base material 31, the heat ray reflective layer 12, and the heat ray absorption layer 13.
And the support base material 31 and the heat ray reflective layer 12 can be peeled. That is, the transfer sheets 30 and 30 ′ are configured such that the peel strength between the support base 31 and the heat ray reflective layer 12 is the weakest among the peel strengths between layers of other layers. Thereby, it peels in the interface of the support base material 31 and the heat ray reflective layer 12, and the heat ray reflective layer 12, or the heat ray reflective layer 12, and the heat ray absorption layer 13 can be transcribe | transferred.
The heat ray reflective layer 12 and the heat ray absorbing layer 13 are as described above. However, in the transfer sheets 30 and 30 ′, the selective reflection layer 12 b is stacked on one surface of the support base 31.

  As for the support base material 31, a glass base material, metal foil, a resin base material, etc. are mentioned. As the support substrate, in addition to glass substrate, acetyl cellulose resin such as triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyester resin such as polylactic acid, polypropylene, polyethylene, polymethylpentene, etc. It is formed using resins such as olefin resin, acrylic resin, polyurethane resin, polyether sulfone, polycarbonate, polysulfone, polyether, polyether ketone, acrylonitrile, methacrylonitrile, cycloolefin polymer, cycloolefin copolymer. Resin base materials.

Here, the support base material 31 may or may not have flexibility, but it is preferable that the support base material 31 has flexibility because the support base material 31 is easily peeled off.
The thickness of the support substrate 31 is preferably in the range of 20 μm or more and 200 μm or less in view of sufficient self-supporting strength and flexibility sufficient to adapt to the production and transfer process of the transfer sheet 30.

  In the transfer sheets 30 and 30 ′, a release treatment is performed on the support substrate 31 so that the peel strength between the support base 31 and the heat ray reflective layer 12 is the weakest among the peel strengths between layers of other layers. And a release layer can be provided. Examples of the mold release treatment include surface treatment such as fluorine treatment and silicone treatment. Examples of the material for the release layer include a fluorine release agent, a silicone release agent, and a wax release agent. Examples of the method for forming the release layer include a method in which a release agent is applied by a coating method such as dip coating, spray coating, or roll coating.

Such a transfer sheet 30 can be produced by laminating the heat ray reflective layer 12 on the support base material 31. The transfer sheet 30 ′ can be produced by further laminating the heat ray absorbing layer 13 on the heat ray reflective layer 12.
Lamination of the heat ray reflective layer 12 to the support base material 31 can be performed following the lamination of the heat ray reflective layer 12 on the transparent substrate 11 in the heat ray shielding member 10 of the first embodiment described above.

  Using the transfer sheets 30 and 30 ', the heat ray shielding members 20 and 20' are obtained as follows. That is, the heat ray reflective member 20, 20 'is produced by transferring the heat ray reflective layer 12, or the heat ray reflective layer 12, and the heat ray absorbing layer 13 of the transfer sheets 30, 30' produced as described above. Specifically, a film in which the adhesive layer 21 is laminated on one surface of the surfaces of the transparent substrate 11 is prepared. And it arrange | positions so that the heat ray reflective layer 12 of the transfer sheet 30 or the heat ray absorption layer 13 of the transfer sheet 30 'may be piled up on the surface by which the adhesive layer 21 is arrange | positioned among this film. After the adhesive layer 21 is cured by an appropriate method (for example, ultraviolet irradiation for an ultraviolet curable adhesive), when the support base 31 is peeled off, the support base 31 is peeled off, and the heat ray shielding member shown in FIG. 20, 20 ′.

  FIG. 8 is a diagram for explaining the fourth embodiment, and shows the layer configuration of the heat ray shielding member 40. The heat ray shielding member 40 includes an adhesive layer 41 containing a heat ray absorbent instead of the adhesive layer 21 of the heat ray shielding member 20 of the third embodiment. Therefore, in the heat ray shielding member 40, the adhesive layer 41 has a function as an adhesive layer and a heat ray absorbing layer. Such a heat ray shielding member 40 also has the same effect as the heat ray reflecting member 10. Moreover, according to the heat ray shielding member 40, since the heat ray absorption layer 13 is not separately required, the layer configuration can be simplified.

  In order to make the adhesive layer 41 have a function of absorbing heat rays, the same heat ray absorbent as that of the heat ray absorbing layer 13 may be made turbid in the same adhesive or adhesive as that of the adhesive layer 21.

  As an example and a comparative example, the heat ray shielding member which changed the central wavelength of reflection was produced and evaluated.

[Heat ray shielding member of Example 1]
As the heat ray shielding member of Example 1, following the heat ray shielding member 10 of the first embodiment, a heat ray reflection layer formed by laminating a transparent substrate and two selective reflection layers arranged on one surface of the transparent substrate. And the heat ray shielding member which has a heat ray absorption layer in the other surface of a transparent substrate was obtained. Such a heat ray shielding member was produced as follows. The central wavelengths of selective reflection of the selective reflection layers are the same and are 900 nm.

(Preparation of coating solution for heat ray absorbing layer formation)
100 parts by mass of pentaerythritol triacrylate which is an ionizing radiation curable monomer, 4 parts by mass of a photopolymerization initiator (BASF, trade name “Irgacure 184”), solar shading dispersion (manufactured by Sumitomo Metal Mining Co., Ltd., product) The name “YMF-02A (cesium-containing tungsten oxide (Cs _0.33 WO ₃ ))) is mixed with 100 parts by weight and dispersed so that the CWO concentration is 14% by mass to form a heat ray absorbing layer. It was set as the coating liquid.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 96.94 parts of the compound represented by the chemical formula (15) and 3.06 parts of a chiral agent (Palicolor (registered trademark) LC-756, manufactured by BASF) were dissolved was prepared. did. In addition, the cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (manufactured by BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie From Japan) was added. This solution was designated as a coating solution A for forming a heat ray reflective layer.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 95.45 parts of the compound represented by the chemical formula (15) and 4.55 parts of a chiral agent (CNL-716, manufactured by ADEKA) were dissolved was prepared. The cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie) based on the rod-shaped compound. (Product made in Japan) was added (solid content 20 mass%). This solution was used as a reflective layer forming coating solution B.

(Formation of heat-absorbing layer)
As a transparent substrate, on the easy-adhesion layer of a 100 μm-thick single-side easy-adhesion-treated polyethylene terephthalate (PET) film (trade name “A4100” manufactured by Toyobo Co., Ltd.), the coating solution for forming the heat ray absorbing layer prepared above. Meyer bar no. 4 was applied. Next, after drying at 80 ° C. for 30 seconds, ultraviolet rays were irradiated at a light amount of 120 mJ / cm ² in a nitrogen gas atmosphere to be cured, and a heat ray absorbing layer was formed on the PET film.

(Preparation of heat ray reflective layer)
On the surface of the transparent substrate on which the easy-adhesion layer on the side opposite to the surface on which the heat ray absorbing layer is formed is not formed on the reflective layer forming coating with a bar coater without an alignment film. Solution B was applied. Subsequently, it hold | maintained at 100 degreeC for 2 minute (s), it was made to dry and the rod-shaped compound was orientated and the coating film was formed. The obtained coating film was irradiated with ultraviolet rays (120 mJ / cm ² ), and a cholesteric structure was fixed on the biaxially stretched film to form a first selective reflection layer. Next, similarly, the reflective layer forming coating solution A was applied on the first selective reflection layer to form a second selective reflection layer.

[Heat ray shielding member of Example 2]
As a heat ray shielding member of Example 2, a transparent substrate, a heat ray reflective layer formed by laminating two selective reflection layers disposed on one surface of the transparent substrate, and a heat ray absorbing layer on the other surface of the transparent substrate are provided. A heat ray shielding member having was obtained. Such a heat ray shielding member was produced as follows. The central wavelength of reflection of this heat ray shielding member is 885 nm.

(Preparation of coating solution for heat ray absorbing layer formation)
In the same manner as in Example 1, a heat ray absorbing layer forming coating solution was prepared.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 96.89 parts of the compound represented by the chemical formula (15) and 3.11 parts of a chiral agent (Palicolor (registered trademark) LC-756, manufactured by BASF) were dissolved was prepared. The cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie) based on the rod-shaped compound. (Product made in Japan) was added (solid content 20 mass%). This solution was designated as a coating solution C for forming a heat ray reflective layer.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 95.40 parts of the compound represented by the chemical formula (15) and 4.60 parts of a chiral agent (CNL-716, manufactured by ADEKA) were dissolved was prepared. The cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie) based on the rod-shaped compound. (Product made in Japan) was added (solid content 20 mass%). This solution was designated as a coating solution D for forming a heat ray reflective layer.

(Formation of heat-absorbing layer)
As a transparent substrate, on the easy-adhesion layer of a 100 μm-thick single-side easy-adhesion-treated polyethylene terephthalate (PET) film (trade name “A4100” manufactured by Toyobo Co., Ltd.), the coating solution for forming the heat ray absorbing layer prepared above. Meyer bar no. 4 was applied. Next, after drying at 80 ° C. for 30 seconds, ultraviolet rays were irradiated at a light amount of 120 mJ / cm ² in a nitrogen gas atmosphere to be cured, and a heat ray absorbing layer was formed on the PET film.

(Preparation of heat ray reflective layer)
On the surface of the transparent substrate on which the easy-adhesion layer on the side opposite to the surface on which the heat ray absorbing layer is formed is not formed on the surface of the transparent substrate with a bar coater without using an alignment film. Was applied. Subsequently, it hold | maintained at 100 degreeC for 2 minute (s), it was made to dry and the rod-shaped compound was orientated and the coating film was formed. The obtained coating film was irradiated with ultraviolet rays (120 mJ / cm ² ), and a cholesteric structure was fixed on the biaxially stretched film to form a first selective reflection layer. Next, similarly, on the first selective reflection layer, the heat ray reflective layer forming coating solution C was applied to form a second selective reflection layer.

[Heat ray shielding member of Example 3]
As a heat ray shielding member of Example 3, a transparent substrate, a heat ray reflective layer formed by laminating two selective reflection layers arranged on one surface of the transparent substrate, and a heat ray absorbing layer on the other surface of the transparent substrate are provided. A heat ray shielding member having was obtained. Such a heat ray shielding member was produced as follows. The central wavelength of reflection of this heat ray shielding member is 854 nm.

(Preparation of coating solution for heat ray absorbing layer formation)
In the same manner as in Example 1, a heat ray absorbing layer forming coating solution was prepared.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 96.78 parts of the compound represented by the chemical formula (15) and 3.22 parts of a chiral agent (Palicolor (registered trademark) LC-756, manufactured by BASF) were dissolved was prepared. In addition, the cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (manufactured by BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie (Manufactured by Japan) was added (solid content 20% by mass). This solution was designated as a coating solution E for forming a heat ray reflective layer.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 95.25 parts of the compound represented by the chemical formula (15) and 4.75 parts of a chiral agent (CNL-716, manufactured by ADEKA) were dissolved was prepared. The cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie) based on the rod-shaped compound. -Japan Co., Ltd.) was added (solid content 20% by weight). This solution was designated as a coating solution F for forming a heat ray reflective layer.

(Formation of heat-absorbing layer)
As a transparent substrate, on the easy-adhesion layer of a 100 μm-thick single-side easy-adhesion-treated polyethylene terephthalate (PET) film (trade name “A4100” manufactured by Toyobo Co., Ltd.), the coating solution for forming the heat ray absorbing layer prepared above. Meyer bar no. 4 was applied. Next, after drying at 80 ° C. for 30 seconds, ultraviolet rays were irradiated at a light amount of 120 mJ / cm ² in a nitrogen gas atmosphere to be cured, and a heat ray absorbing layer was formed on the PET film.

(Preparation of heat ray reflective layer)
On the surface of the transparent substrate on which the easy-adhesion layer opposite to the surface on which the heat ray absorbing layer is formed is not formed, the reflective layer forming coating is performed with a bar coater without an alignment film. Solution F was applied. Subsequently, it hold | maintained at 100 degreeC for 2 minute (s), it was made to dry and the rod-shaped compound was orientated and the coating film was formed. The obtained coating film was irradiated with ultraviolet rays (120 mJ / cm ² ), and a cholesteric structure was fixed on the biaxially stretched film to form a first selective reflection layer. Next, similarly, the reflective layer forming coating solution E was applied on the first reflective layer to form a second selective reflective layer.

[Heat ray shielding member of Comparative Example 1]
As a heat ray shielding member of Comparative Example 1, a transparent substrate, a heat ray reflective layer formed by laminating two selective reflection layers disposed on one surface of the transparent substrate, and a heat ray absorbing layer on the other surface of the transparent substrate are provided. A heat ray shielding member having was obtained. Such a heat ray shielding member was produced as follows. The central wavelength of reflection of this heat ray shielding member is 833 nm.

(Formation of heat-absorbing layer)
As in Example 1, a heat ray absorbing layer was formed.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 96.59 parts of the compound represented by the chemical formula (15) and 3.41 parts of a chiral agent (Palicolor (registered trademark) LC-756, manufactured by BASF) were dissolved was prepared. In addition, the cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (manufactured by BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie (Manufactured by Japan) was added (solid content 20% by mass). This solution was designated as a coating solution G for forming a heat ray reflective layer.

(Preparation of coating solution for heat ray reflective layer formation)
As a rod-shaped compound, a cyclohexanone solution in which 95.16 parts of the compound represented by the chemical formula (15) and 4.84 parts of a chiral agent (CNL-716, manufactured by ADEKA) were dissolved was prepared. The cyclohexanone solution contains 5.0% by mass of a photopolymerization initiator (BASF, trade name “Irgacure 907”) and 0.03% by mass of a leveling agent (BYK361N, Big Chemie) based on the rod-shaped compound. (Product made in Japan) was added (solid content 20 mass%). This solution was designated as a coating solution H for forming a heat ray reflective layer.

  As in Example 1, a heat ray absorbing layer was formed. Furthermore, Example 1 was used except that the heat ray reflective layer forming coating solution H was used when forming the first selective reflection layer, and the heat ray reflective layer forming coating solution G was used when forming the second selective reflection layer. A reflective layer was prepared in the same manner as described above.

[Evaluation]
About the heat ray shielding member which concerns on Example 1- Example 3 and the comparative example 1, L * a * b * table | surface about the transmittance | permeability and reflectance for every wavelength, reflected light, and transmitted light, changing the incident angle of light Evaluation by color system was performed. Details are as follows.

  In the evaluation, a 1.1 mm-thick non-alkali glass substrate (trade name: Eagle XG manufactured by Corning) was prepared, and a 10 μm-thick optical adhesive sheet was bonded using a laminating roller. Next, among the heat ray shielding members produced in Examples 1 to 3 and Comparative Example 1, the heat ray absorbing layer side was bonded to the optical adhesive sheet of a non-alkali glass substrate. Therefore, the evaluation was performed with the layer configuration of alkali-free glass substrate / optical adhesive sheet / heat ray absorbing layer / transparent substrate / heat ray reflective layer.

  The transmittance and reflectance for each wavelength were targeted for transmittance and reflectance from a wavelength of 300 nm to a wavelength of 2500 nm. For the measurement, a UV-visible near-infrared spectrophotometer V-670 manufactured by JASCO Corporation was used. The measurement was performed by using an integrating sphere unit so that the diffuse reflectance and total transmittance including regular reflection were made incident from the heat ray reflective layer side. The variable angle measurement used an automatic absolute reflectance measurement unit (the light source was switched between a deuterium lamp and a halogen lamp at a switching wavelength of 340 nm).

  The measurement of the color is performed using a V-7100 UV-visible spectrophotometer manufactured by JASCO Corporation so that N-polarized light (45 °) is incident from the reflective layer side and the incident angle is 10 ° from 5 ° to 55 °. The transmittance and the reflectance were measured while changing the values in the above, and the a * of the transmitted light, the b * of the transmitted light, the a * of the reflected light, and the b * of the reflected light were calculated using the attached color calculation software. (D65 light source, visual field 2 ° color matching function JIS Z8701-1999).

[result]
Table 1 shows the center wavelength of selective reflection, a * of transmitted light at an incident angle of 55 °, b * of transmitted light, a * of reflected light, b * of reflected light, and a of transmitted light at an incident angle of 5 °. *, The difference between b * of transmitted light, a * of reflected light, and b * of reflected light.

  As can be seen from Table 1, in Comparative Example 1, the difference in transmission a * and the difference in reflection a * are larger than those in Examples 1 to 3, and the change in color depending on the angle is large. For example, if the difference in transmission a * is large and swings to the minus side, it means greenish, and it becomes difficult to identify the green one. Further, when the difference in reflection a * greatly fluctuates to the plus side, it looks reddish.

DESCRIPTION OF SYMBOLS 10 Heat ray shielding member 11 Transparent substrate 12 Heat ray reflective layer 12a Selective reflection layer 12b Selective reflection layer 13 Heat ray absorption layer

Claims (15)

A heat ray shielding member that reflects infrared rays,
A transparent substrate;
A heat ray reflective layer comprising at least two selective reflective layers each having a cholesteric liquid crystal that reflects infrared rays;
A heat ray absorbing layer that absorbs infrared rays,
The total sunlight transmittance is 41% or more and 70% or less, and the visible light transmittance is 70% or more.
Heat ray shielding member. Chromaticity a * of transmitted light when light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member, and chromaticity of transmitted light when light is incident from a direction inclined by 5 ° the difference from a * is 3.0 or less,
Chromaticity b * of transmitted light when light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member, and chromaticity of transmitted light when light is incident from a direction inclined by 5 ° difference between b * and 3.0 or less,
The heat ray shielding member according to claim 1. Chromaticity a * of reflected light when light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member, and chromaticity of reflected light when light is incident from a direction inclined by 5 ° the difference from a * is 6.4 or less,
Chromaticity b * of reflected light when light is incident from a direction inclined by 55 ° with respect to the normal of the surface of the heat ray shielding member, and chromaticity of reflected light when light is incident from a direction inclined by 5 ° the difference from b * is 6.4 or less,
The heat ray shielding member according to claim 2.   One of the selective reflection layers is a layer including a cholesteric liquid crystal having a center wavelength of reflection of 834 nm or more and a right-handed spiral structure, and the other one of the selective reflection layers has a center wavelength of reflection of 834 nm or more. The heat ray shielding member according to any one of claims 1 to 3, wherein the heat ray shielding member is a layer containing a cholesteric liquid crystal having a left-handed spiral structure.   The one of the selective reflection layers is a layer containing a cholesteric liquid crystal having a central wavelength of reflection of 834 nm or more, and the other one of the selective reflection layers is a layer containing a cholesteric liquid crystal having a different central wavelength of reflection. The heat ray shielding member according to any one of 1 to 3.   The heat ray shielding member according to claim 5, wherein the turning direction of the spiral structure of the one selective reflection layer is the same as the turning direction of the spiral structure of the other one selective reflection layer.   The heat ray shielding member according to claim 5, wherein the turning direction of the spiral structure of the one selective reflection layer is opposite to the turning direction of the spiral structure of the other one selective reflection layer.   The heat ray shielding member according to claim 1, wherein the heat ray reflective layer is laminated on one surface of the transparent substrate with an adhesive layer.   The heat ray shielding member according to claim 8, wherein the adhesive layer contains a heat ray absorbent, and the adhesive layer also serves as the heat ray absorbent layer.   The heat ray shielding member according to any one of claims 1 to 9, wherein the cholesteric liquid crystal is a chiral nematic liquid crystal in which a chiral agent is mixed with a nematic liquid crystal.   The heat ray shielding member according to claim 10, wherein each of the nematic liquid crystal and the chiral agent has a functional group capable of crosslinking, and the cholesteric structure is fixed by crosslinking the functional groups.   The heat ray shielding member according to claim 11, wherein at least one of the nematic liquid crystal and the chiral agent is a compound having an acrylate structure.   The heat ray shielding according to any one of claims 1 to 12, wherein the heat ray absorbing layer contains a resin and an inorganic near infrared ray absorbent having an average particle diameter of 40 nm to 200 nm, and the inorganic near infrared ray absorbent is a tungsten oxide compound. Element. The tungsten oxide-based compound includes at least one element selected from the group consisting of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn, W as tungsten, O as oxygen, 0 When 001 ≦ x / y ≦ 1.1 and 2.2 ≦ z / y ≦ 3.0,
MxWyOz
The heat ray shielding member of Claim 13 represented by these.   The heat ray shielding member according to claim 14, wherein the tungsten oxide compound is cesium-containing tungsten oxide.

Images