JP6952580B2 - Polarizing film, protective plate for image display device, and retardation film - Google Patents

Description

The present invention relates to a polarizing film, a retardation film, and a protective plate for an image display device, specifically, a polarizing film, a retardation film, and a protective plate for an image display device, which are preferably used for optical applications.

Large liquid crystal displays are widely used as digital signage and information displays. Since these large liquid crystal displays are often installed outdoors, a protective plate such as a glass plate is provided on the surface for the purpose of preventing damage. An antireflection film is provided on the surface of the protective plate in order to prevent reflection and reflection of strong external light such as sunlight and improve visibility (see Patent Document 1).

By the way, in the liquid crystal image display device installed outdoors, thermal damage due to sunlight can be mentioned as a defect other than the reflection of external light. That is, there is a problem that internal parts such as a liquid crystal cell are excessively heated and deteriorated. Therefore, it is considered to provide an infrared reflective film on the surface of the protective plate (see Patent Document 2).

The infrared reflective film of Patent Document 2 discloses an infrared reflective film including an infrared reflective layer composed of a first metal oxide layer, a metal layer, and a second metal oxide layer on a transparent film base material in this order.

Since the infrared reflective film of Patent Document 2 includes a metal layer, it exhibits good infrared reflective ability as compared with other infrared reflective films.

Japanese Unexamined Patent Publication No. 11-258592 Japanese Unexamined Patent Publication No. 2014-167617

However, the infrared reflective film of Patent Document 2 includes not only near-infrared region (for example, wavelength region of 800 to 1600 nm) but also visible light, particularly visible light close to the near-infrared region (for example, red color having a wavelength of 600 to 800 nm). There is a problem that light) is also reflected. Therefore, there is room for improvement in suppressing the reflection of external light.

Further, if the liquid crystal image display device is left in a moist environment such as rainy weather, water may infiltrate between the infrared reflective film of Patent Document 2 and the protective plate. At that time, water may not be discharged between the infrared reflective layer (particularly the metal layer) having low moisture permeability and the protective plate, and water may accumulate excessively, resulting in fogging inside the protective plate. It may cause a problem that transparency is reduced. In addition, the presence of excessively accumulated water may promote corrosion of the metal layer and deteriorate the appearance. It should be noted that the deterioration of the appearance due to the presence of water does not occur in the infrared reflective film made of oxide, and is a problem peculiar to the infrared reflective film provided with the metal layer.

An object of the present invention is a protective plate for an image display device, a polarizing film, and a polarizing film capable of suppressing the reflection of visible light of external light while reflecting infrared rays, and suppressing deterioration of transparency and deterioration of appearance in a moist environment. The purpose is to provide a retardation film.

In the present invention [1], a first transparent resin film, an infrared reflecting layer, and a polarizer are provided in this order on one side in the thickness direction, and the infrared reflecting layer includes a first inorganic oxide layer, a metal layer, and a first layer. A polarizing film including two inorganic oxide layers in order is included.

The present invention [2] includes the polarizing film according to [1], further comprising a 1/4 wavelength layer between the infrared reflecting layer and the polarizing element.

The present invention [3] further includes a second transparent resin film between the infrared reflecting layer and the polarizing element, and the thickness of the second transparent resin film is 10 μm or more and 100 μm or less [1]. Alternatively, the polarizing film according to [2] is included.

The present invention [4] includes the polarizing film according to any one of [1] to [3], further comprising a third transparent resin film on one side of the polarizing element in the thickness direction.

In the present invention [5], the polarizing film according to [4], wherein the third transparent resin film is an ultraviolet absorbing layer.

The polarizing film according to any one of [1] to [5], wherein the present invention [6] further includes a first pressure-sensitive adhesive layer between the first transparent resin film and the infrared reflective layer. Includes.

The present invention [7], moisture permeability of the first transparent resin film, is 5g / m 2 · ^24h or more, includes a polarizing film of any one of [1] to [6].

The present invention [8] includes the polarizing film according to any one of [1] to [7], wherein the metal layer is a silver layer or a silver alloy layer.

According to the present invention [9], the polarizing film according to any one of [1] to [8], wherein the first inorganic oxide layer and the second inorganic oxide layer contain an indium-based oxide. Includes.

In the present invention [10], the polarizing film according to any one of [1] to [9], a second pressure-sensitive adhesive layer provided on one side of the polarizing film in the thickness direction, and the second pressure-sensitive adhesive. It includes a protective plate for an image display device, which includes a transparent protective plate provided on one side of the layer in the thickness direction.

In the present invention [11], a first transparent resin film, an infrared reflecting layer, and a 1/4 wavelength layer are provided in order on one side in the thickness direction, and the infrared reflecting layer includes a first inorganic oxide layer and a metal layer. And a retardation film including a second inorganic oxide layer in order.

The present invention [12] further includes a second transparent resin film, and includes the retardation film according to [11], wherein the thickness of the second transparent resin film is 10 μm or more and 100 μm or less.

The present invention [13] is characterized in that a first pressure-sensitive adhesive layer is further provided between the first transparent resin film and the infrared reflective layer, according to any one of [11] and [12]. Includes the described retardation film.

According to the protective plate for an image display device of the present invention including the polarizing film and the retardation film of the present invention, infrared rays can be reflected. Therefore, it is possible to suppress the temperature rise of the internal parts of the image display device and reduce the deterioration of the image display device.

Further, since the reflection of visible light of external light can be suppressed, the reflection of external light can be reduced.

Further, in a moist environment, fogging of the protective plate for the image display device can be suppressed, so that transparency can be maintained. Further, in a moist environment, corrosion of the metal layer can be suppressed and a good appearance can be maintained.

FIG. 1 shows a side view of an embodiment of a polarizing film. FIG. 2 shows a side view of the protective plate provided with the polarizing film shown in FIG. FIG. 3 shows a side view of a modified example of the polarizing film (the embodiment in which each layer is replaced). FIG. 4 shows a side view of a modified example of the polarizing film (the embodiment without the third pressure-sensitive adhesive layer and the second transparent resin film). FIG. 5 shows a side view of a modified example of the polarizing film (the embodiment without the third pressure-sensitive adhesive layer, the second 1/4 wavelength layer, and the fourth pressure-sensitive adhesive layer). FIG. 6 shows a side view of a modified example of the polarizing film (the embodiment without the third pressure-sensitive adhesive layer, the second transparent resin film, the second 1/4 wavelength layer, and the fourth pressure-sensitive adhesive layer). FIG. 7 shows a side view of a modified example of the polarizing film (the embodiment without the first pressure-sensitive adhesive layer, the second transparent resin film, the second 1/4 wavelength layer, and the fourth pressure-sensitive adhesive layer). FIG. 8 shows a modification of the polarizing film (first pressure-sensitive adhesive layer, first 1/4 wavelength layer, third pressure-sensitive adhesive layer, second transparent resin film, second 1/4 wavelength layer, fourth pressure-sensitive adhesive layer). The side view of the third transparent resin film (the embodiment) is shown. FIG. 9 shows a side view of the polarizing film of the comparative example. FIG. 10 shows a graph showing the relationship between the measured wavelength and the light reflectance measured in the examples.

1. 1. Polarizing Film An embodiment of the polarizing film 1 of the present invention will be described with reference to FIG.

In FIG. 1, the vertical direction of the paper surface is the vertical direction (thickness direction, first direction), the upper side of the paper surface is the upper side (one side in the thickness direction, one side in the first direction), and the lower side of the paper surface is the lower side (thickness direction). The other side, the other side in the first direction). Further, the horizontal direction and the depth direction of the paper surface are plane directions orthogonal to the vertical direction. Specifically, it conforms to the direction arrows in each figure.

The polarizing film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a plane direction orthogonal to the thickness direction, and has a flat upper surface and a flat lower surface (two main surfaces). The polarizing film 1 is, for example, a component provided in an image display device (such as a liquid crystal image display device), that is, it is not an image display device. That is, the polarizing film 1 is a component for manufacturing an image display device or the like, and does not include an image display element such as a liquid crystal cell 19 or a light source 20 such as an LED, and is a device that can be distributed independently and can be used industrially. Is.

Specifically, as shown in FIG. 1, the polarizing film 1 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflecting layer 4, and a first 1/4 wavelength layer 5, in that order. A third pressure-sensitive adhesive layer 6, a second transparent resin film 7, a polarizer 8, a second 1/4 wavelength layer 9, a fourth pressure-sensitive adhesive layer 10, and a third transparent resin film 11. Be prepared. Preferably, the polarizing film 1 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflective layer 4, a first 1/4 wavelength layer 5, a third pressure-sensitive adhesive layer 6, and the like. 2 The transparent resin film 7 is composed of only a polarizer 8, a second 1/4 wavelength layer 9, a fourth pressure-sensitive adhesive layer 10, and a third transparent resin film 11. Hereinafter, each layer will be described in detail.

(1st transparent resin film)
The first transparent resin film 2 is the lowermost layer of the polarizing film 1 and is a support material for ensuring the mechanical strength of the polarizing film 1. Further, the first transparent resin film 2 is a water-permeable layer for allowing water that has penetrated into the polarizing film 1 or the protective plate 18 for an image display device to permeate and be discharged to the outside of the polarizing film 1 (lower side in FIG. 1). Is.

The first transparent resin film 2 has transparency, flexibility and moisture permeability.

Examples of the material constituting the first transparent resin film 2 include a cellulose resin such as triacetyl cellulose (TAC), for example, a cyclic polyolefin resin such as a cycloolefin polymer, for example, an acrylic resin, a phenylmaleimide resin, a polycarbonate resin, and a polyester. Examples thereof include resins, polyimide resins, polyamide resins, and polystyrene resins. These materials can be used alone or in combination of two or more. From the viewpoints of transparency, mechanical strength, moisture permeability, optical isotropic property and the like, cyclic polyolefin resin and cellulose resin are preferable, cellulose resin is more preferable, and TAC is further preferable. ..

Further, the first transparent resin film 2 may contain a known additive such as an ultraviolet absorber described later.

The first transparent resin film 2 preferably has substantially no retardation. Substantially having no retardation means that the retardation at a wavelength of 550 nm is, for example, 20 nm or less, preferably 10 nm or less, more preferably 5 nm or less, and further preferably 0 nm in the thickness direction.

The thickness of the first transparent resin film 2 is, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and for example, 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less. be.

The thickness of each layer (excluding the infrared reflective layer 4) such as the first transparent resin film 2 can be measured using, for example, a film thickness meter (“Digital Dial Gauge DG-205” manufactured by Peacock). .. The thickness can also be measured by acquiring and observing a cross-sectional SEM image.

Moisture permeability of the first transparent resin film 2, for example, 5 g ^/ m 2 · 24h or more, preferably, 10 g ^/ m 2 · 24h or more, more preferably, 30 g ^/ m 2 · 24h or more, more preferably, 50 g / m ² · 24h or more, especially preferably not 100g ^/ m 2 · 24h or more, and is, for example, 5000g ^/ m 2 · 24h or less, preferably, 3000g ^/ m 2 · 24h or less, more preferably, 1500 g / m ² · 24h or less, more preferably, 1000g ^/ m 2 · 24h or less, particularly preferably not more than 800g ^/ m 2 · 24h. By setting the moisture permeability to the above lower limit or higher, the water that penetrates into the polarizing film 1, in particular, the water that penetrates between the first transparent resin film 2 and the infrared reflective layer 4 can be quickly discharged to the outside. It is possible to suppress the retention of water between them. As a result, fogging of the polarizing film 1 and corrosion of the metal layer 13 can be suppressed. On the other hand, by setting the moisture permeability to the above upper limit or less, it is possible to prevent excessive infiltration of water between the first transparent resin film 2 and the infrared reflective layer 4 and suppress corrosion of the metal layer 13.

Moisture permeability can be measured, for example, by a test according to JIS K 7129: 2008 Annex B. Specifically, it is obtained by using a measuring device "PERMATRAN W3 / 33" manufactured by MOCON, and the test conditions are 40 ° C. and 90% relative humidity.

Further, the lower surface of the first transparent resin film 2 may be surface-treated, if necessary. As the surface treatment, for example, etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical formation, and oxidation, and undercoating treatment can be performed. In addition, the first transparent resin film 2 can be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like.

(First adhesive layer)
The first pressure-sensitive adhesive layer 3 adheres the first transparent resin film 2 and the infrared reflective layer 4, and allows water existing on the surface of the infrared reflective layer 4 to pass through the first transparent resin film 2 or. This is a layer for discharging to the outside through the end portion of the first pressure-sensitive adhesive layer 3. The first pressure-sensitive adhesive layer 3 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the first transparent resin film 2 so as to be in contact with the upper surface of the first transparent resin film 2. There is.

The first pressure-sensitive adhesive layer 3 is prepared from the pressure-sensitive adhesive composition. The composition of the pressure-sensitive adhesive composition is not limited, but for example, acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive (butyl rubber, etc.), silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, polyurethane-based pressure-sensitive adhesive, polyamide-based pressure-sensitive adhesive, epoxy-based pressure-sensitive adhesive. Examples thereof include agents, vinyl alkyl ether-based pressure-sensitive adhesives, fluororesin-based pressure-sensitive adhesives, and preferably, acrylic-based pressure-sensitive adhesives from the viewpoint of adhesiveness and moisture permeability.

The pressure-sensitive adhesive composition includes, for example, additives such as fillers, antioxidants, softeners, rocking agents, lubricants, pigments, scorch inhibitors, stabilizers, UV absorbers, colorants, fungicides, and flame retardants. May be contained.

The pressure-sensitive adhesive composition preferably contains an antioxidant. Antioxidants are not limited, but benzotriazole-based compounds are preferred. Examples of the benzotriazole-based compound include 1,2,3-benzotriazole, 5-methyl-1H-benzotriazole, 4-methylbenzotriazole, and nitrobenzotriazole-based compounds. The content of the antioxidant in the pressure-sensitive adhesive composition is, for example, 0.01% by mass or more and 10% by mass or less.

The thickness of the first pressure-sensitive adhesive layer 3 is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and for example, 300 μm or less, preferably 150 μm or less, more preferably 50 μm or less. be. By setting the thickness of the first pressure-sensitive adhesive layer 3 to the above lower limit or more, the bondability is excellent. Further, by setting the thickness of the first pressure-sensitive adhesive layer 3 to be equal to or less than the above upper limit, the handleability is excellent.

The thickness of the pressure-sensitive adhesive layer such as the first pressure-sensitive adhesive layer 3 can be measured using, for example, a film thickness meter (“Digital Dial Gauge DG-205” manufactured by Peacock). The thickness can also be measured by acquiring and observing a cross-sectional SEM image.

(Infrared reflective layer)
The infrared reflecting layer 4 is a layer for transmitting visible light while reflecting infrared rays incident on the polarizing film 1.

The infrared reflective layer 4 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the first pressure-sensitive adhesive layer 3 so as to be in contact with the upper surface of the first pressure-sensitive adhesive layer 3.

The infrared reflecting layer 4 includes a first inorganic oxide layer 12, a metal layer 13, and a second inorganic oxide layer 14 in this order from the bottom. That is, the infrared reflective layer 4 includes a first inorganic oxide layer 12 arranged on the upper side of the first pressure-sensitive adhesive layer 3, a metal layer 13 arranged on the upper side of the first inorganic oxide layer 12, and a metal layer 13. It is provided with a second inorganic oxide layer 14 arranged on the upper side of the above. Further, the infrared reflective layer 4 preferably includes only the first inorganic oxide layer 12, the metal layer 13, and the second inorganic oxide layer 14.

The thickness of the infrared reflective layer 4, that is, the total thickness of the first inorganic oxide layer 12, the metal layer 13, and the second inorganic oxide layer 14 is, for example, 20 nm or more, preferably 60 nm or more, and, for example, It is 150 nm or less, preferably 120 μm or less, and more preferably 100 nm or less.

(First inorganic oxide layer)
The first inorganic oxide layer 12, together with the second inorganic oxide layer 14 described later, is an optical adjustment layer for suppressing visible light reflection of the metal layer 13 and improving the visible light transmittance of the infrared reflecting layer 4. .. It is also a barrier layer for preventing deterioration of the metal layer 13 due to the invasion of components such as hydrogen and carbon contained in the first transparent resin film 2 and the first pressure-sensitive adhesive layer 3 into the metal layer 13.

The first inorganic oxide layer 12 is the lowest layer in the infrared reflective layer 4, has a film shape (including a sheet shape), and has a first pressure-sensitive adhesive layer on the entire upper surface of the first pressure-sensitive adhesive layer 3. It is arranged so as to be in contact with the upper surface of 3.

Examples of the inorganic oxide forming the first inorganic oxide layer 12 include In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, W, Fe, and so on. Examples thereof include metal oxides formed from at least one metal selected from the group consisting of Pb, Ni, Nb, and Cr. The metal oxide can be further doped with the metal atoms shown in the above group, if necessary.

The inorganic oxide preferably includes an oxide containing indium oxide (indium-based oxide) from the viewpoint of ensuring excellent transparency, and more preferably an indium tin composite oxide (ITO). Be done. As used herein, the term "ITO" may be any composite oxide containing at least indium (In) and tin (Sn), and may contain additional components other than these. Examples of the additional component include metal elements other than In and Sn, and examples thereof include the metal elements shown in the above group and combinations thereof. The content of the additional component is not particularly limited, but is, for example, 5% by mass or less.

The content of tin oxide (SnO ₂ ) contained in ITO is, for example, 0.5% by mass or more, preferably 3% by mass or more, based on the total amount of tin oxide and indium oxide (In ₂ O _3). For example, it is 35% by mass or less, preferably 20% by mass or less. The content of indium oxide (In ₂ O ₃ ) is the balance of the content of tin oxide (SnO _{2). By setting the content of tin oxide (SnO 2} ) contained in ITO in the above range, the crystallinity of the ITO film can be adjusted.

The first inorganic oxide layer 12 may be crystalline or amorphous. Preferably, it is amorphous. This makes it possible to reduce defects in the manufacturing process (for example, the heating process for obtaining crystalline material).

The thickness of the first inorganic oxide layer 12 is, for example, 5 nm or more, preferably 20 nm or more, and for example, 100 nm or less, preferably 60 nm or less. When the thickness of the first inorganic oxide layer 12 is within the above range, it is easy to adjust the visible light transmittance of the infrared reflecting layer 4 to a high level. The thickness of the first inorganic oxide layer 12 is measured, for example, by observing a cross section with a transmission electron microscope (TEM).

(Metal layer)
The metal layer 13 is a layer for reflecting infrared rays and imparting transparency (visible light transmission) together with the first inorganic oxide layer 12 and the second inorganic oxide layer 14.

The metal layer 13 has a film shape (including a sheet shape), and is arranged on the upper surface of the first inorganic oxide layer 12 so as to be in contact with the upper surface of the first inorganic oxide layer 12.

The metal forming the metal layer 13 is not limited as long as it is a metal having a high infrared reflectance, but for example, Ti, Si, Nb, In, Zn, Sn, Au, Ag, Cu, Al, Co, Cr, It consists of one metal selected from the group consisting of Ni, Pb, Pd, Pt, Cu, Ge, Ru, Nd, Mg, Ca, Na, W, Zr, Ta and Hf, or two of them. Examples thereof include alloys containing the above metals.

As the metal, silver (Ag) and a silver alloy are preferable, and a silver alloy is more preferable, from the viewpoint of exhibiting excellent infrared reflectivity.

The silver alloy contains silver as a main component and other metals as a sub component. The metal element of the subcomponent is not limited. Examples of the silver alloy include Ag-Cu alloy, Ag-Pd alloy, Ag-Pd-Cu alloy, Ag-Pd-Cu-Ge alloy, Ag-Cu-Au alloy, Ag-Cu-In alloy, and Ag-Cu. -Sn alloy, Ag-Ru-Cu alloy, Ag-Ru-Au alloy, Ag-Nd alloy, Ag-Mg alloy, Ag-Ca alloy, Ag-Na alloy, Ag-Ni alloy, Ag-Ti alloy, Ag- In alloy, Ag—Sn alloy and the like can be mentioned. From the viewpoint of durability, the silver alloy preferably includes Ag-Cu alloy, Ag-Cu-In alloy, Ag-Cu-Sn alloy, Ag-Pd alloy, Ag-Pd-Cu alloy and the like.

The content ratio of silver in the silver alloy is, for example, 80% by mass or more, preferably 90% by mass or more, and for example, 99.9% by mass or less. The content of other metals in the silver alloy is the balance of the silver content described above.

From the viewpoint of infrared reflectivity and transparency, the thickness of the metal layer 13 is, for example, 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 14 nm or more, and for example, 80 nm or less. It is preferably 30 nm or less, more preferably 25 nm or less, still more preferably 20 nm or less, and particularly preferably 15 nm or less. In particular, when the thickness of the metal layer 13 is 14 nm or more and 80 nm or less, deterioration of the appearance due to a moist environment can be further suppressed. The thickness of the metal layer 13 is measured, for example, by observing a cross section with a transmission electron microscope (TEM).

(Second inorganic oxide layer)
The second inorganic oxide layer 14, together with the first inorganic oxide layer 12, is an optical adjustment layer for suppressing the visible light reflectance of the metal layer 13 and improving the visible light transmittance of the infrared reflecting layer 4. Further, the second inorganic oxide layer 14 is a barrier layer for preventing deterioration of the metal layer 13 due to invasion of external oxygen, moisture, etc. into the metal layer 13.

The second inorganic oxide layer 14 is the uppermost layer of the infrared reflective layer 4, has a film shape (including a sheet shape), and is in contact with the entire upper surface of the metal layer 13 and the upper surface of the metal layer 13. It is arranged so that.

Examples of the inorganic oxide forming the second inorganic oxide layer 14 include the inorganic oxides exemplified in the first inorganic oxide layer 12, preferably containing indium oxide, and more preferably made of ITO.

When the second inorganic oxide layer 14 is made of ITO, the content of tin oxide (SnO ₂ ) contained in ITO is the same as that of the first inorganic oxide layer 12.

The second inorganic oxide layer 14 may be crystalline or amorphous. It is preferably amorphous from the viewpoint of reducing defects in the manufacturing process (for example, a high heat heating process for obtaining crystalline material). Further, from the viewpoint of moisture resistance, it is preferably a semi-crystalline material containing crystal grains in an amorphous film.

The thickness of the second inorganic oxide layer 14 is, for example, 5 nm or more, preferably 20 nm or more, and for example, 100 nm or less, preferably 60 nm or less. When the thickness of the second inorganic oxide layer 14 is within the above range, it is easy to adjust the visible light transmittance of the infrared reflecting layer 4 to a high level. The thickness of the second inorganic oxide layer 14 is measured, for example, by observing a cross section with a transmission electron microscope (TEM).

The ratio (T2 / T1) of the thickness T2 of the second inorganic oxide layer 14 to the thickness T1 of the first inorganic oxide layer 12 is, for example, 0.5 or more, preferably 0.75 or more, and for example, for example. It is 1.5 or less, preferably 1.25 or less. When the ratio (T2 / T1) is in the above range, deterioration of the metal layer 13 in a moist environment can be further suppressed.

The ratio (T2 / T3) of the thickness T2 of the second inorganic oxide layer 14 to the thickness T3 of the metal layer 13 is, for example, 1.5 or more, preferably 2.0 or more, more preferably 3.0 or more. And, for example, 10 or less, preferably 4.0 or less.

(First 1/4 wavelength layer)
The first 1/4 wavelength layer 5 is a layer for converting linearly polarized light that has passed through a polarizer 8 described later into substantially circularly polarized light.

The first 1/4 wavelength layer 5 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the infrared reflecting layer 4 so as to be in contact with the upper surface of the infrared reflecting layer 4. ..

The retardation of the first quarter wavelength layer 5 at a wavelength of 550 nm is, for example, in the range of 137.5 nm ± 40 nm, preferably in the range of 137.5 nm ± 20 nm, more preferably in the range of 137.5 nm ± 10 nm. ..

The angle of the first 1/4 wavelength layer 5 in the slow axis direction with respect to the absorption axis direction of the polarizer 8 is, for example, in the range of 45 ° ± 10 °, preferably in the range of 45 ° ± 2. Is.

Specific examples of the first 1/4 wavelength layer 5 include a stretched film in which a resin film is stretched, a film in which a liquid crystal polymer is oriented, and the like. Examples of the material of the resin film include cyclic polyolefin resins such as cycloolefin polymers and polycarbonate resins.

The thickness of the first 1/4 wavelength layer 5 is, for example, 3 μm or more, preferably 10 μm or more, and for example, 300 μm or less, preferably 100 μm or less.

(Third adhesive layer)
The third pressure-sensitive adhesive layer 6 is a layer for adhering the first 1/4 wavelength layer 5 and the second transparent resin film 7.

The third adhesive layer 6 has a film shape (including a sheet shape), and is in contact with the entire upper surface of the first 1/4 wavelength layer 5 and the upper surface of the first 1/4 wavelength layer 5. It is arranged so that.

The third pressure-sensitive adhesive layer 6 is prepared from the pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive composition include the pressure-sensitive adhesive composition described above in the first pressure-sensitive adhesive layer 3, and preferably an acrylic pressure-sensitive adhesive.

The thickness of the third pressure-sensitive adhesive layer 6 is, for example, 1 μm or more, preferably 5 μm or more, and for example, 300 μm or less, preferably 150 μm or less, more preferably 50 μm or less. By setting the thickness of the third pressure-sensitive adhesive layer 6 to the above lower limit or more, the bondability is excellent. Further, by setting the thickness of the third pressure-sensitive adhesive layer 6 to be equal to or less than the above upper limit, the moisture permeability is excellent.

(Second transparent resin film)
The second transparent resin film 7 is a layer that supports the polarizer 8 (described later). It is also a layer that reduces deterioration of the polarizer 8 in a thermal environment by dispersing or passing water contained in the polarizer 8 inside the second transparent resin film 7. Further, the distance between the infrared reflective layer 4 and the transparent protective plate 17 (described later) is widened, and the water stored on the surface of the infrared reflective layer 4 is dispersed inside the second transparent resin film 7, or the second transparent resin is used. It is also a layer for suppressing fogging and corrosion of the metal layer 13 by removing water through the edge of the film 7.

The second transparent resin film 7 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the third pressure-sensitive adhesive layer 6 so as to be in contact with the upper surface of the third pressure-sensitive adhesive layer 6. There is.

Examples of the material constituting the second transparent resin film 7 include the materials described above in the first transparent resin film 2, preferably cyclic polyolefin resin and cellulose resin, and more preferably cellulose resin. More preferably, TAC can be mentioned.

Further, the second transparent resin film 7 may contain a known additive such as an ultraviolet absorber described later.

The thickness of the second transparent resin film 7 is, for example, 3 μm or more, preferably 10 μm or more, and for example, 200 μm or less, preferably 100 μm or less. By setting the thickness of the second transparent resin film 7 to the above lower limit or more, it has a function of supporting the polarizer 8. Further, by setting the thickness to the above upper limit or less, sufficient moisture permeability can be maintained, and deterioration of the polarizer 8 in a thermal environment can be easily suppressed.

Moisture permeability of the second transparent resin film 7, for example, 5 g ^/ m 2 · 24h or more, preferably, 10 g ^/ m 2 · 24h or more, more preferably, 30 g ^/ m 2 · 24h or more, more preferably, 50 g / m ² · 24h or more, especially preferably not 100g ^/ m 2 · 24h or more, and is, for example, 5000g ^/ m 2 · 24h or less, preferably, 3000g ^/ m 2 · 24h or less, more preferably, 1500 g / m ² · 24h or less, more preferably, 1000g ^/ m 2 · 24h or less, particularly preferably not more than 800g ^/ m 2 · 24h. By setting the moisture permeability of the second transparent resin film 7 within the above range, deterioration of the polarizer 8 in a thermal environment can be effectively reduced.

(Polarizer)
The polarizer 8 is a layer for converting light into linearly polarized light.

The polarizer 8 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the second transparent resin film 7 so as to be in contact with the upper surface of the second transparent resin film 7.

As the polarizer 8, for example, a dichroic substance (iodine, dichroic dye) is adsorbed on a hydrophilic resin film such as a polyvinyl alcohol film (PVA) or an ethylene-vinyl acetate copolymer partially saponified film. , A film stretched uniaxially and the like. Further, polyethylene-based films such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride can also be mentioned.

The thickness of the polarizer 8 is, for example, 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and for example, 200 μm or less, preferably 100 μm or less, more preferably 50 μm or less, still more preferably. , 30 μm or less.

(Second quarter wavelength layer)
The second 1/4 wavelength layer 9 is a layer for emitting light incident on the polarizer 8 from the light source 20 as circularly polarized light.

The second 1/4 wavelength layer 9 has a film shape (including a sheet shape) and is arranged on the entire upper surface of the polarizer 8 so as to be in contact with the upper surface of the polarizer 8.

The second 1/4 wavelength layer 9 may be obtained by converting linearly polarized light that has passed through the polarizer 8 into substantially circularly polarized light, and may be the same as the first 1/4 wavelength layer 5.

(4th adhesive layer)
The fourth pressure-sensitive adhesive layer 10 is a layer for adhering the second 1/4 wavelength layer 9 and the third transparent resin film 11.

The fourth pressure-sensitive adhesive layer 10 has a film shape (including a sheet shape), and is in contact with the entire upper surface of the second 1/4 wavelength layer 9 and the upper surface of the second 1/4 wavelength layer 9. It is arranged so that.

The fourth pressure-sensitive adhesive layer 10 is prepared from the pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive composition include the pressure-sensitive adhesive composition described above in the first pressure-sensitive adhesive layer 3, and preferably an acrylic pressure-sensitive adhesive.

The thickness of the fourth pressure-sensitive adhesive layer 10 is, for example, 1 μm or more, preferably 5 μm or more, and for example, 300 μm or less, preferably 150 μm or less, more preferably 50 μm or less.

(Third transparent resin film)
The third transparent resin film 11 is an ultraviolet absorbing layer for absorbing ultraviolet rays of external light and reducing deterioration of the polarizer 8.

The third transparent resin film 11 is the uppermost layer of the polarizing film 1, has a film shape (including a sheet shape), and has a film shape (including a sheet shape) on the entire upper surface of the fourth pressure-sensitive adhesive layer 10 and the upper surface of the fourth pressure-sensitive adhesive layer 10. It is arranged so as to come into contact with.

The third transparent resin film 11 has ultraviolet absorption. Specifically, for example, it contains a transparent resin film and an ultraviolet absorber.

Examples of the material constituting the transparent resin film include the above-mentioned materials in the first transparent resin film 2, preferably cellulose resin, and more preferably TAC and the like.

The material of the ultraviolet absorber is not limited, and examples thereof include benzotriazole-based compounds, hydroxyphenyltriazine-based compounds, benzophenone-based compounds, salicylate ester-based compounds, cyanoacrylate-based compounds, and nickel complex salt-based compounds.

The content of the ultraviolet absorber is, for example, 0.001% by mass or more, preferably 0.1% by mass or more, and for example, 20% by mass or less, preferably 20% by mass or less, based on the total amount of the third transparent resin film 11. Is 5% by mass or less.

The third transparent resin film 11 preferably has substantially no retardation.

The thickness of the third transparent resin film 11 is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and for example, 300 μm or less, preferably 100 μm or less, more preferably 70 μm or less. be.

(Manufacturing method of polarizing film)
Next, a method of manufacturing the polarizing film 1 will be described. In order to manufacture the polarizing film 1, for example, the above layers are arranged (laminated) in the above order.

For example, in particular, (1) a first transparent resin film 2, (2) a first laminated body composed of an infrared reflective layer 4 and a first 1/4 wavelength layer 5, (3) a second transparent resin film 7, and a polarizer. A second laminate composed of 8 and a second 1/4 wavelength layer 9 and (4) a third transparent resin film 11 are prepared, and these are used as an adhesive layer (first adhesive layer 3, third adhesive layer). 6. Arranged via the fourth pressure-sensitive adhesive layer 10).

As the first transparent resin film 2, the second laminated body and the third transparent resin film 11, known or commercially available ones can be used.

In the first laminated body, for example, the infrared reflecting layer 4 is laminated by a dry method on one surface of a known or commercially available first 1/4 wavelength layer 5.

Specifically, each of the second inorganic oxide layer 14, the metal layer 13, and the first inorganic oxide layer 12 is arranged in order on one surface of the first 1/4 wavelength layer 5 by a dry method.

Examples of the dry method include a vacuum deposition method, a sputtering method, and an ion plating method. Preferably, a sputtering method is used. Specifically, the magnetron sputtering method can be mentioned.

Examples of the gas used in the sputtering method include an inert gas such as Ar. Further, if necessary, a reactive gas such as oxygen can be used in combination. When the reactive gas is used in combination, the flow rate ratio of the reactive gas is not particularly limited, and the ratio of the flow rate of the reactive gas to the flow rate of the inert gas is, for example, 0.1 / 100 or more, preferably 0.1/100 or more. It is 1/100 or more, and for example, 5/100 or less.

Specifically, in the formation of the first inorganic oxide layer 12 and the second inorganic oxide layer 14, an inert gas and a reactive gas are preferably used in combination as the gas. In forming the metal layer 13, an inert gas is preferably used alone as the gas.

When the sputtering method is adopted, the target material includes the above-mentioned inorganic oxides or metals constituting each layer.

The power source used in the sputtering method is not limited, and examples thereof include a DC power source, an MF / AC power source, and an RF power source used alone or in combination, and a DC power source is preferable.

As a result, the infrared reflective layer 4 in which the second inorganic oxide layer 14, the metal layer 13, and the first inorganic oxide layer 12 are formed in this order is formed on one surface of the first 1/4 wavelength layer 5. The first laminate is obtained.

The first inorganic oxide layer 12 and the second inorganic oxide layer 14 obtained by the dry method are amorphous. Therefore, if necessary, heat treatment may be carried out in order to crystallize them.

Each film and laminate is then placed via an adhesive layer.

The pressure-sensitive adhesive layer may be arranged, for example, by applying a liquid pressure-sensitive adhesive composition to one surface of each film or laminate and drying it, or a sheet-shaped pressure-sensitive adhesive composition (pressure-sensitive adhesive layer). It may be arranged as it is on one surface of each film or laminate.

As a result, the polarizing film 1 is obtained.

The total thickness of the polarizing film 1 is, for example, 2 μm or more, preferably 20 μm or more, more preferably 50 μm or more, still more preferably 100 μm or more, and for example, 1000 μm or less, preferably 500 μm or less, more preferably. Is 300 μm or less, more preferably 200 μm or less, and particularly preferably 150 μm or less.

In this polarizing film 1, the average reflectance of near infrared rays having a wavelength of 800 to 1600 nm is, for example, 10% or more, preferably 20% or more, more preferably 30% or more, and for example, 100% or less. be.

The visible light transmittance of the polarizing film 1 is, for example, 60% or more, preferably 80% or more, more preferably 85% or more, and for example, 95% or less.

(Action effect)
The polarizing film 1 includes a first transparent resin film 2, an infrared reflecting layer 4, and a polarizing element 8 in this order. Further, the infrared reflective layer 4 includes a first inorganic oxide layer 12, a metal layer 13, and a second inorganic oxide layer 14 in this order.

Therefore, since the metal layer 13 has excellent reflectance in the near-infrared region (particularly 800 to 1600 nm), the temperature rise of the internal parts (liquid crystal cell 19 and the like) due to external light is suppressed, and the deterioration of the image display device is reduced. be able to.

Further, the polarizing film 1 can also suppress reflected light of visible light (for example, 600 to 800 nm) in the visible light region, particularly in the vicinity of the infrared region. Specifically, the infrared reflecting layer 4 also slightly reflects visible light (for example, 600 to 800 nm) in the vicinity of the near-outline region. However, in the polarizing film 1, since the infrared reflecting layer 4 is arranged on the liquid crystal cell 19 side (opposite to the protective plate 18) of the polarizing element 8 in the image display device, it is reflected by the infrared reflecting layer 4. The external light returning to the visual recognition side passes through the polarizer 8 and becomes linearly polarized light in which a part of the light is absorbed. Therefore, the external light returning to the visual recognition side is reduced, and the reflection of the external light can be reduced. Further, in the polarizing film 1 in which the first 1/4 wavelength layer 5 is arranged between the polarizer 8 and the infrared reflecting layer 4, the external light reflected by the infrared reflecting layer 4 and returning to the viewing side is polarized. It is absorbed by the child 8 and is not emitted to the visual side. Therefore, the redness derived from the reflected light of the infrared reflecting layer 4 can be significantly reduced.

Further, since the infrared reflective layer 4 is laminated on the first transparent resin film 2, water that has penetrated into the vicinity of the infrared reflective layer 4 can be appropriately discharged to the outside through the first transparent resin film 2. .. Therefore, fogging of the polarizing film 1 and corrosion of the metal layer 13 can be suppressed. Therefore, the transparency of the polarizing film 1 can be maintained.

In particular, moisture permeability of the first transparent resin film 2, if it is 5 g / m 2 · ^24h or more, more reliably, it is possible to discharge water to the outside. Therefore, fogging of the polarizing film 1 and corrosion of the metal layer 13 can be further suppressed.

Further, a second transparent resin film 7 is provided between the infrared reflecting layer 4 and the polarizer 8. In particular, when the thickness of the second transparent resin film 7 is 10 μm or more and 100 μm or less, a space (second transparent resin film 7) capable of dispersing water is provided between the infrared reflecting layer 4 and the polarizer 8. Therefore, the fogging of the polarizing film 1 can be further suppressed.

Further, the polarizing film 1 further includes a first 1/4 wavelength layer 5 between the infrared reflecting layer 4 and the polarizing element 8. Therefore, the reflection of external light can be suppressed more reliably. Specifically, the external light is converted into circularly polarized light by the polarizer 8 and the first 1/4 wavelength layer 5. After that, the circularly polarized light is reflected by the liquid crystal cell 19 and converted into linearly polarized light again by the first 1/4 wavelength layer 5. Since the linearly polarized light (external light) at this time coincides with the absorption axis of the polarizer 8, it is completely absorbed by the polarizer 8.

Further, the polarizing film 1 further includes a third transparent resin film 11 on the upper side (visual side) of the polarizing element 8. When the third transparent resin film 11 is an ultraviolet absorbing layer, deterioration of the polarizer 8 can be reduced.

Further, the polarizing film 1 further includes a first pressure-sensitive adhesive layer 3 between the first transparent resin film 2 and the infrared reflecting layer 4. Therefore, the water stored on the surface of the infrared reflective layer 4 can be reliably discharged to the outside via the first transparent resin film 2.

Further, when the metal layer 13 is a silver layer or a silver alloy layer, infrared rays can be more reliably reflected.

Further, when the first inorganic oxide layer 12 and the second inorganic oxide layer 14 both contain an indium-based conductive oxide, the visible light transmittance is further excellent.

Of the members constituting the polarizing film 1, the portion below the polarizing element 8, that is, the first transparent resin film 2, the first pressure-sensitive adhesive layer 3, the infrared reflecting layer 4, and the first 1/4 wavelength. The layer 5, the third pressure-sensitive adhesive layer 6, and the second transparent resin film 7 constitute an embodiment of the retardation film 15 of the present invention. Specifically, one embodiment of the retardation film 15 includes a first transparent resin film 2, a first adhesive layer 3, an infrared reflective layer 4, a first 1/4 wavelength layer 5, and a third. The pressure-sensitive adhesive layer 6 and the second transparent resin film 7 are provided in this order.

The retardation film 15 has a film shape (including a sheet shape) having a predetermined thickness, extends in a plane direction orthogonal to the thickness direction, and has a flat upper surface and a flat lower surface (two main surfaces). The retardation film 15 is, for example, a component provided in an image display device (such as a liquid crystal image display device), that is, it is not an image display device. That is, the polarizing film 1 is a component for manufacturing an image display device or the like, and does not include an image display element such as a liquid crystal cell 19 or a light source 20 such as an LED, and is a device that can be distributed independently and can be used industrially. Is.

The retardation film 15 can maintain transparency even in a moist environment while reflecting infrared rays. Further, by arranging the polarizer 8, the visible light reflection of external light can be efficiently suppressed.

The polarizing film 1 and the retardation film 15 are provided in, for example, an optical device. Examples of the optical device include an image display device such as a liquid crystal image display device, a dimming device, and the like. More specifically, the polarizing film 1 and the retardation film 15 are preferably used as a protective plate 18 for an image display device arranged on the front surface (visual side surface) of the image display device.

2. A protective plate for an image display device An embodiment of a protective plate 18 for an image display device is shown in FIG.

As shown in FIG. 2, the image display device protective plate 18 includes a polarizing film 1, a second adhesive layer 16, and a transparent protective plate 17 in this order from the bottom. The upper side is the visual recognition side, and the lower side is the liquid crystal cell side.

The second pressure-sensitive adhesive layer 16 is a layer for adhering the polarizing film 1 and the transparent protective plate 17.

The second adhesive layer 16 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the third transparent resin film 11 so as to be in contact with the upper surface of the third transparent resin film 11. There is.

The second pressure-sensitive adhesive layer 16 is prepared from the pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive composition include the pressure-sensitive adhesive composition described in the first pressure-sensitive adhesive layer 3, and preferably an acrylic pressure-sensitive adhesive.

The thickness of the second pressure-sensitive adhesive layer 16 is, for example, 1 μm or more, preferably 5 μm or more, and for example, 300 μm or less, preferably 150 μm or less, more preferably 50 μm or less.

The transparent protective plate 17 is a layer for protecting the internal member of the image display device such as the liquid crystal cell 19 against impact and dirt from the outside.

The transparent protective plate 17 has a substantially flat plate shape in a plan view, and is arranged on the entire upper surface of the second pressure-sensitive adhesive layer 16 so as to be in contact with the upper surface of the second pressure-sensitive adhesive layer 16.

The transparent protective plate 17 is transparent and has an appropriate thickness and mechanical strength.

Examples of the transparent protective plate 17 include a resin plate made of a hard resin such as an acrylic resin and a polycarbonate resin, for example, a glass plate and the like.

A functional layer such as an antireflection layer (AR) may be formed on the upper surface and / or the lower surface of the transparent protective plate 17.

The thickness of the transparent protective plate 17 is, for example, 10 μm or more, preferably 500 μm or more, and for example, 100 mm or less, preferably 10 mm or less, more preferably 5 mm or less.

Then, the protective plate 18 for the image display device is used, for example, arranged so as to face the liquid crystal cell 19 and the light source 20 shown in the virtual line of FIG. Although not shown, the liquid crystal cell 19 includes a liquid crystal layer, two polarizers sandwiching the liquid crystal layer, and a color filter.

The image display device protective plate 18 has a film shape (including a sheet shape) having a predetermined thickness, extends in a plane direction orthogonal to the thickness direction, and has a flat upper surface and a flat lower surface (two main surfaces). .. The image display device protective plate 18 is, for example, a component provided in an image display device (such as a liquid crystal image display device), that is, it is not an image display device. That is, the polarizing film 1 is a component for manufacturing an image display device or the like, and does not include an image display element such as a liquid crystal cell 19 or a light source 20 such as an LED, and is a device that can be distributed independently and can be used industrially. Is.

Since the protective plate 18 for the image display device includes the polarizing film 1, it is possible to suppress the reflection of visible light of external light while reflecting infrared rays. In addition, transparency can be maintained even in a moist environment.

3. 3. Modification Example A modification of the polarizing film 1 will be described with reference to FIGS. 3 to 8. In other embodiments, the same members as those in the embodiment of FIG. 1 described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, the polarizing film 1 is, in order from the bottom, a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflective layer 4, a first 1/4 wavelength layer 5, and a third pressure-sensitive adhesive. A layer 6, a second transparent resin film 7, a polarizer 8, a second 1/4 wavelength layer 9, a fourth pressure-sensitive adhesive layer 10, and a third transparent resin film 11 are provided, for example. , As shown in FIG. 3, the first 1/4 wavelength layer 5 and the second transparent resin film 7 may be interchanged with each other, and further, the second 1/4 wavelength layer 9 and the third transparent resin film 11 may be replaced with each other. They may be interchanged with each other. That is, the polarizing film 1 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflective layer 4, a second transparent resin film 7, a third pressure-sensitive adhesive layer 6, and the like, in order from the bottom. A 1/4 wavelength layer 5 of 1 may be provided, a polarizer 8, a 3rd transparent resin film 11, a 4th pressure-sensitive adhesive layer 10, and a 2nd 1/4 wavelength layer 9.

In this case, the retardation film 15 shown in FIG. 3 is composed of the first transparent resin film 2, the first adhesive layer 3, the infrared reflective layer 4, the second transparent resin film 7, and the second transparent resin film 15 in this order from the bottom. 3 The pressure-sensitive adhesive layer 6 and the first 1/4 wavelength layer 5 are provided.

The polarizing film 1 and the retardation film 15 shown in FIG. 3 also have the same effects as those of the polarizing film 1 and the retardation film 15 shown in FIG.

Further, in addition to the embodiment shown in FIG. 3, as shown in FIG. 4, the polarizing film 1 does not have to include the third pressure-sensitive adhesive layer 6 and the second transparent resin film 7. That is, the polarizing film 1 shown in FIG. 4 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflecting layer 4, a first 1/4 wavelength layer 5, and a polarizing element in this order from the bottom. 8, a third transparent resin film 11, a fourth pressure-sensitive adhesive layer 10, and a second 1/4 wavelength layer 9.

In this case, the retardation film 15 shown in FIG. 4 has a first transparent resin film 2, a first adhesive layer 3, an infrared reflective layer 4, and a first 1/4 wavelength layer 5 in this order from the bottom. And.

The polarizing film 1 and the retardation film 15 shown in FIG. 4 also have the same effects as those of the polarizing film 1 and the retardation film 15 shown in FIG. Preferably, the polarizing film 1 and the retardation film 15 shown in FIG. 1 can be mentioned from the viewpoint that fogging and corrosion of the metal layer 13 can be further reduced by providing the second transparent resin film 7.

Further, as shown in FIG. 5, the polarizing film 1 does not have to include the third pressure-sensitive adhesive layer 6, the second 1/4 wavelength layer 9, and the fourth pressure-sensitive adhesive layer 10. That is, the polarizing film 1 shown in FIG. 5 has a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflecting layer 4, a first 1/4 wavelength layer 5, and a second, in order from the bottom. A transparent resin film 7, a polarizer 8, and a third transparent resin film 11 are provided.

The retardation film 15 shown in FIG. 5 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflecting layer 4, a first 1/4 wavelength layer 5, and a first, in order from the bottom. 2 A transparent resin film 7 is provided.

The polarizing film 1 and the retardation film 15 shown in FIG. 5 also have the same effects as those of the polarizing film 1 and the retardation film 15 shown in FIG.

Further, as shown in FIG. 6, the polarizing film 1 includes a third pressure-sensitive adhesive layer 6, a second transparent resin film 7, a second 1/4 wavelength layer 9, and a fourth pressure-sensitive adhesive layer 10. It doesn't have to be. That is, the polarizing film 1 shown in FIG. 6 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflecting layer 4, a first 1/4 wavelength layer 5, and a polarizing element in this order from the bottom. 8 and a third transparent resin film 11.

The retardation film 15 shown in FIG. 6 includes a first transparent resin film 2, a first pressure-sensitive adhesive layer 3, an infrared reflective layer 4, and a first 1/4 wavelength layer 5 in this order from the bottom. ..

The polarizing film 1 and the retardation film 15 shown in FIG. 6 also have the same effects as those of the polarizing film 1 and the retardation film 15 shown in FIG. Preferably, the polarizing film 1 and the retardation film 15 shown in FIG. 1 can be mentioned from the viewpoint that fogging and corrosion of the metal layer 13 can be further reduced by providing the second transparent resin film 7.

Further, as shown in FIG. 7, the polarizing film 1 includes a first pressure-sensitive adhesive layer 3, a second transparent resin film 7, a second 1/4 wavelength layer 9, and a fourth pressure-sensitive adhesive layer 10. It is not necessary, and the first 1/4 wavelength layer 5 and the third pressure-sensitive adhesive layer 6 may be interchanged with each other. That is, the polarizing film 1 shown in FIG. 7 includes a first transparent resin film 2, an infrared reflecting layer 4, a third pressure-sensitive adhesive layer 6, a first 1/4 wavelength layer 5, and a polarizing element in this order from the bottom. 8 and a third transparent resin film 11.

The retardation film 15 shown in FIG. 7 includes a first transparent resin film 2, an infrared reflective layer 4, a third adhesive layer 6, and a first 1/4 wavelength layer 5 in this order from the bottom. ..

The polarizing film 1 and the retardation film 15 shown in FIG. 7 also have the same effects as those of the polarizing film 1 and the retardation film 15 shown in FIG. Preferably, the polarizing film 1 and the retardation film 15 shown in FIG. 1 are mentioned from the viewpoint of further reducing fogging and corrosion of the metal layer 13 by providing the first pressure-sensitive adhesive layer 3 and the second transparent resin film 7. Be done.

Further, as shown in FIG. 8, the polarizing film 1 includes a first pressure-sensitive adhesive layer 3, a first 1/4 wavelength layer 5, a third pressure-sensitive adhesive layer 6, a second transparent resin film 7, and a second layer. It is not necessary to provide the 1/4 wavelength layer 9 of 2 and the fourth pressure-sensitive adhesive layer 10 and the third transparent resin film 11. That is, the polarizing film 1 shown in FIG. 8 includes a first transparent resin film 2, an infrared reflecting layer 4, and a polarizing element 8 in this order from the bottom.

The polarizing film 1 shown in FIG. 8 also has the same effect as that of the polarizing film 1 shown in FIG. Preferably, by providing the first pressure-sensitive adhesive layer 3 and the second transparent resin film 7, it is possible to further reduce fogging and corrosion of the metal layer 13, and by providing the first 1/4 wavelength layer 5. From the viewpoint of reliably reducing the reflection of external light, the polarizing film 1 and the retardation film 15 shown in FIG. 1 can be mentioned.

Further, in the polarizing film 1 shown in FIGS. 1 to 8, the third transparent resin film 11 is an ultraviolet absorbing layer, but for example, the third transparent resin film may be a non-ultraviolet absorbing layer. In this case, the second pressure-sensitive adhesive layer 16 in the protective plate 18 for the image display device is preferably a pressure-sensitive adhesive layer capable of absorbing ultraviolet rays. Specifically, the second pressure-sensitive adhesive layer 16 contains, for example, an ultraviolet absorber. Such a protective plate 18 for an image display device also has the same effect as that of the protective plate 18 for an image display device including the polarizing film 1 shown in FIGS. 1 to 8.

Although not shown, the infrared reflective layer 4 may include a layer other than the first inorganic oxide layer 12, the metal layer 13, and the second inorganic oxide layer 14. For example, the second metal layer and the third inorganic oxide layer may be provided on the side of the second inorganic oxide layer 14 opposite to the metal layer 13, or the second metal of the third inorganic oxide layer. A third metal layer and a fourth inorganic oxide layer may be further provided on the side opposite to the layer.

Further, one surface or both of the first transparent resin film 2 may be further provided with functional layers such as an antifouling layer, an adhesive layer, a water repellent layer, an antireflection layer, and an oligomer prevention layer, which are necessary functions. It can be applied as appropriate according to the above. The functional layer preferably comprises a layer containing an organic resin.

Examples and comparative examples are shown below, and the present invention will be described in more detail. The present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned "mode for carrying out the invention", and the compounding ratios corresponding to them ( Substitute the upper limit value (value defined as "less than or equal to" or "less than") or the lower limit value (value defined as "greater than or equal to" or "excess") such as content ratio), physical property value, parameter, etc. be able to.

Example 1
As shown in FIG. 1, a TAC film (thickness 65 μm, first transparent resin film), acrylic pressure-sensitive adhesive layer (thickness 23 μm, first pressure-sensitive adhesive layer), infrared reflective layer, λ / 4 plate (thickness 50 μm, first). 1/4 wavelength layer), acrylic pressure-sensitive adhesive layer (thickness 23 μm, third pressure-sensitive adhesive layer), TAC film (thickness 40 μm, second transparent resin film), polarizer (thickness 22 μm, iodine-impregnated PVA), λ / 4 plate (Thickness 50 μm, second 1/4 wavelength layer), acrylic pressure-sensitive adhesive layer (thickness 23 μm, fourth pressure-sensitive adhesive layer), UV absorber-containing TAC film (thickness 60 μm, third transparent resin film), from below. The polarizing films of the examples were prepared by laminating them so as to be arranged in order.

As the infrared reflective layer, amorphous ITO (thickness 40 nm, first inorganic oxide layer), silver-copper alloy (thickness 8 nm, metal layer) and amorphous ITO (thickness 40 nm, second inorganic oxide layer) A laminate made of was used.

Next, as shown in FIG. 2, an acrylic pressure-sensitive adhesive layer (thickness 23 μm, second pressure-sensitive adhesive layer) and a low-reflection glass plate (thickness 5 mm, transparent protective plate) are laminated in this order on the upper surface of the polarizing film, and an image is displayed. A protective plate for the device was produced.

Example 2
A polarizing film and a protective plate for an image display device were produced in the same manner as in Example 1 except that the thickness of the metal layer of the infrared reflecting layer was changed to 12 nm.

Example 3
A polarizing film and a protective plate for an image display device were produced in the same manner as in Example 1 except that the thickness of the metal layer of the infrared reflecting layer was changed to 20 nm.

Comparative Example 1
As shown in FIG. 9, TAC film (thickness 65 μm, first transparent resin film), acrylic pressure-sensitive adhesive layer (thickness 23 μm, first pressure-sensitive adhesive layer), λ / 4 plate (thickness 50 μm, first 1/4 wavelength). Layer), polarizer (thickness 22 μm, iodine-impregnated PVA), TAC film (thickness 40 μm, second transparent resin film), acrylic pressure-sensitive adhesive layer (thickness 23 μm, third pressure-sensitive adhesive layer), λ / 4 plate (thickness 50 μm, The second 1/4 wavelength layer) and the infrared reflective layer were laminated so as to be arranged in this order from the bottom to prepare a polarizing film of Comparative Example.

The infrared reflecting layer used was the same as that of the infrared reflecting layer of Example 1.

Next, in the same manner as in Example 1, an acrylic pressure-sensitive adhesive layer (thickness 23 μm, second pressure-sensitive adhesive layer) and a low-reflection glass plate (thickness 5 mm, transparent protective plate) are laminated in this order on the upper surface of the polarizing film for comparison. An example protective plate for an image display device was produced.

(Humidity permeability)
The moisture permeability of the first transparent resin film, the second transparent resin film, and the third transparent resin film was measured at a temperature of 40 ° C. and a relative humidity of 90 using a water vapor permeability measuring device (“PERMATRAN W3 / 33”, manufactured by MOCON). It was measured under the condition of%. Moisture permeability of the transparent resin film are all 200g ^/ m 2 · 24h or more was less than 800g ^/ m 2 · 24h.

(Reflectance)
Visible light and infrared light are irradiated to the protective plate for the image display device of each Example and Comparative Example using a spectrophotometer (“U-4100”, manufactured by Hitachi High-Technologies Corporation), and light at each wavelength. The reflectance was measured. The graph at this time is shown in FIG. Table 1 shows the average reflectance in the near-infrared region (the average value of the reflectance at a wavelength of 5 nm pitch) in the near infrared region of 800 to 1600 nm.

As is clear from FIG. 10, in the polarizing films of Examples 1 and 2, the reflection of visible light (particularly, red light having a wavelength of 600 to 800 nm) is reduced as compared with the polarizing film of Comparative Example 1. I understand. It can also be seen that infrared rays having a wavelength of 800 to 1600 nm are well reflected. Furthermore, it can be seen that Example 2 reflects more infrared rays than Example 1 while having substantially the same reflectance of visible light. Further, the polarizing film of Example 3 has a configuration in which a large amount of infrared rays are reflected as compared with Comparative Example 1. Therefore, in the wavelength range of 750 to 800 nm near the infrared region, the reflection is increased as compared with Comparative Example 1, but in the visible light region having a wavelength of 600 to 750 nm or less, the visible light reflection is smaller than that of Comparative Example 1. From this, it can be seen that even when a polarizing film having a high infrared reflectance of more than 40% is used, the reflection in the majority red visible light wavelength region can be effectively suppressed.

(Cloudy in a moist environment)
First, the haze before humidification was measured using a haze meter (“HGM-2DP”, manufactured by Suga Test Instruments Co., Ltd.) for the protective plate for the image display device of each Example and Comparative Example. In addition, the protective plates for image display devices of each Example and Comparative Example were placed under wet conditions of 60 ° C. and 95% RH for 500 hours, and then the haze after humidification was measured. These results are shown in Table 1.

(exterior)
After placing the protective plate for the image display device of each example and the comparative example under a wet condition of 60 ° C. and 95% RH for 500 hours, the image display device is protected by ^{observing with an optical microscope (observation area: 300 cm 2).} The appearance of the plate (specifically, punctate corrosion of the infrared reflective layer) was evaluated.

When no appearance defects (corrosion) with a maximum length of 400 μm or more are observed, it is evaluated as ◎, and when almost no appearance defects (corrosion) with a maximum length of 400 μm or more are observed, it is evaluated as ○, and the maximum length is 400 μm or more. The case where the appearance defects of the above were scattered was evaluated as x. The results are shown in Table 1.

1 Polarizing film 2 1st transparent resin film 3 1st pressure-sensitive adhesive layer 4 Infrared reflective layer 5 1st 1/4 wavelength layer 7 2nd transparent resin film 8 Polarizer 11 3rd transparent resin film 12 1st inorganic oxide layer 13 Metal layer 14 Second inorganic oxide layer 15 Phase difference film 16 Second adhesive layer 17 Transparent protective plate 18 Protective plate for image display device

Claims (13)

A first transparent resin film, an infrared reflecting layer, and a polarizer are provided in this order on one side in the thickness direction.
The infrared reflective layer includes a first inorganic oxide layer, a metal layer, and a second inorganic oxide layer in this order.
The second inorganic oxide layer is characterized by a semicrystalline der Rukoto containing crystal grains in amorphous film, a polarizing film. The polarizing film according to claim 1, further comprising a 1/4 wavelength layer between the infrared reflecting layer and the polarizing element. A second transparent resin film is further provided between the infrared reflecting layer and the polarizer.
The polarizing film according to claim 1 or 2, wherein the thickness of the second transparent resin film is 10 μm or more and 100 μm or less. The polarizing film according to any one of claims 1 to 3, further comprising a third transparent resin film on one side of the polarizing element in the thickness direction. The polarizing film according to claim 4, wherein the third transparent resin film is an ultraviolet absorbing layer. The polarizing film according to any one of claims 1 to 5, further comprising a first pressure-sensitive adhesive layer between the first transparent resin film and the infrared reflective layer. The polarizing film according to any one of claims 1 to 6, wherein the first transparent resin film has a moisture permeability of 5 g / m 2.24 h or more. The polarizing film according to any one of claims 1 to 7, wherein the metal layer is a silver layer or a silver alloy layer. The polarizing film according to any one of claims 1 to 8, wherein the first inorganic oxide layer and the second inorganic oxide layer contain an indium-based oxide. The polarizing film according to any one of claims 1 to 9, and the polarizing film.
A second pressure-sensitive adhesive layer provided on one side of the polarizing film in the thickness direction,
A protective plate for an image display device, which comprises a transparent protective plate provided on one side of the second pressure-sensitive adhesive layer in the thickness direction. A first transparent resin film, an infrared reflective layer, and a quarter wavelength layer are provided in order on one side in the thickness direction.
The infrared reflective layer includes a first inorganic oxide layer, a metal layer, and a second inorganic oxide layer in this order.
The second inorganic oxide layer is characterized by a semicrystalline der Rukoto containing crystal grains in amorphous film, a retardation film. Further equipped with a second transparent resin film
The retardation film according to claim 11, wherein the thickness of the second transparent resin film is 10 μm or more and 100 μm or less. The retardation film according to any one of claims 11 or 12, wherein a first pressure-sensitive adhesive layer is further provided between the first transparent resin film and the infrared reflective layer.

Images