Polarizing film, polarizing plate, and optical laminate

Abstract

Provided is a polarizing film having a non-polarizing part which has excellent shape maintenance performance and in which the complex color of the non-polarizing part is suppressed. A polarizing film according to an embodiment of the present invention comprises a resin film containing a dichroic organic dye, and has a non-polarizing part. In one embodiment, when the polarizing film is subjected to a humid heat test in which the polarizing film is left to stand for 24 hours in an environment of 65 DEG C and 90% RH, the rate of change in the outer periphery of the non-polarizing portion before and after the humid heat test of the polarizing film is 3.0% or less. In another embodiment, when the polarizing film is subjected to a humid heat test in which the polarizing film is left to stand for 24 hours in an environment of 65 DEG C and 90% RH, the rate of change in the area of the non-polarizing portion before and after the humid heat test of the polarizing film is 5.0% or less.

Description

Technical Field

[0001] The present invention relates to a polarizing film, a polarizing plate, and an optical laminate. Background Art

[0002] In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices) are rapidly becoming popular. In such image display devices, a polarizing film containing iodine is typically used. In addition, in order to cope with the diversification of the shape and high functionality of image display devices, a polarizing film having polarization performance is required in part. As a method for manufacturing such a polarizing film, there is a known technology for bleaching a portion of the polarizing film by irradiating a laser with a wavelength of at least 1500nm or less to form a non-polarized portion (for example, Patent Document 1). Alternatively, there is a known technology for bleaching a portion of the polarizing film by contacting it with an alkaline substance to form a non-polarized portion (for example, Patent Document 2). However, the non-polarized portion of the polarizing film manufactured by the method described in Patent Document 1 can maintain its shape, but sometimes the non-polarized portion (bleached portion) will recolor over time. The non-polarized portion of the polarizing film manufactured by the method described in Patent Document 2 can suppress recoloring over time, but the shape maintenance performance is insufficient.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-081482

[0006] Patent Document 1: Japanese Patent Application No. 2015-525725 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a polarizing film having a non-polarizing portion, excellent in shape-maintaining performance of the non-polarizing portion, and with suppressed color reproduction in the non-polarizing portion.

[0009] Means for solving problems

[0010] [1] A polarizing film according to one embodiment of the present invention is composed of a resin film containing a dichroic organic pigment and has a non-polarizing portion. When the polarizing film is subjected to a wet heat test in an environment of 65°C and 90% RH for 24 hours, the rate of change of the periphery of the non-polarizing portion before and after the wet heat test is less than 3.0%.

[0011] [2] Another embodiment of the present invention is a polarizing film composed of a resin film containing a dichroic organic pigment and having a non-polarizing portion. When the polarizing film is subjected to a wet heat test in an environment of 65°C and 90% RH for 24 hours, the change rate of the area of ​​the non-polarizing portion before and after the wet heat test is less than 5.0%.

[0012] [3] In the above [1] or [2], the resin film comprises a polyvinyl alcohol-based resin, and the dichroic organic pigment comprises one selected from an azo dye represented by the following formula (1), a salt of the azo dye, a chelate of the azo dye, or a mixture thereof:

[0013]

[0014] (In formula (1), X and Z each represent an atomic group represented by (2) to (13) below; Y represents an atomic group represented by (14) to (29) below; and m represents an integer from 0 to 6)

[0015] [Chemical Formula 2]

[0016]

[0017] (In formulas (2) to (13), A represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms which may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms which may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; n represents an integer from 0 to 5; o represents an integer from 0 to 4; p represents an integer from 0 to 3; q represents an integer from 0 to 2; and r represents 0 or 1)

[0018] [Chemical Formula 3]

[0019]

[0020] (In formulas (14) to (29), B represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms that may contain a branched structure, a cyclic structure, a double bond or a triple bond; R, n, o, p, q and r are the same as those in the above formulas (2) to (13)).

[0021] [4] In any one of the above [1] to [3], in the above polarizing film, when the content ratio of the dichroic organic pigment in the polarizing film excluding the non-polarizing portion is set to 100 mass%, the content ratio of the dichroic organic pigment in the above non-polarizing portion is 3.0 mass% or less.

[0022] [5] In any one of the above [1] to [4], the haze value of the non-polarizing portion is 5.0% or less.

[0023] [6] In any one of the above [1] to [5], when the above polarizing film is subjected to a wet heat test in an environment of 65°C and 90% RH for 24 hours, the absolute value of the change in the single transmittance of the non-polarizing portion before and after the wet heat test is less than 3.0.

[0024] [7] In any one of [1] to [6] above, the non-polarized portion is a laser decolorized portion.

[0025] [8] According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate comprises the polarizing film according to any one of [1] to [7] above, and a protective layer provided on at least one side of the polarizing film.

[0026] [9] In the above [8], the polarizing plate is provided with protective layers on both sides of the polarizing film.

[0027]

[10] According to another aspect of the present invention, an optical laminate is provided. The optical laminate comprises the polarizing film according to any one of [1] to [7] above, a protective layer provided on one side of the polarizing film, and a retardation film provided on the other side of the polarizing film. The retardation film has an in-plane retardation Re(550) of 100 nm to 180 nm, and an angle formed between the absorption axis of the polarizing film and the slow axis of the retardation film is 40° to 50°.

[0028] Effects of the Invention

[0029] According to the embodiment of the present invention, a polarizing film having a non-polarizing portion, having excellent shape-maintaining performance of the non-polarizing portion and suppressing color reproduction of the non-polarizing portion can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic cross-sectional view of a polarizing plate including a polarizing film according to an embodiment of the present invention.

[0031] Figure 2 is included Figure 1 Schematic cross-sectional view of an optical laminate of a polarizing plate.

[0032] Description of Reference Numerals

[0033] 10 polarizing filters

[0034] 11 Polarizing film

[0035] 12 protection layers

[0036] 20 phase difference film

[0037] 100 optical laminates DETAILED DESCRIPTION

[0038] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments. In addition, the drawings are schematically shown for ease of understanding and are different from actual lengths, widths, thicknesses, ratios of layers, etc.

[0039] (1) Refractive index (nx, ny, nz)

[0040] “nx” is the refractive index in the direction where the in-plane refractive index is maximum (ie, the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis (ie, the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0041] (2) In-plane retardation (Re)

[0042] "Re(λ)" is the in-plane retardation measured at 23°C using light of a wavelength of λ nm. For example, "Re(550)" is the in-plane retardation measured at 23°C using light of a wavelength of 550 nm. When the thickness of a layer (film) is d (nm), Re(λ) is calculated using the formula: Re(λ) = (nx - ny) × d.

[0043] (3) Angle

[0044] When referring to an angle in this specification, the angle includes both clockwise and counterclockwise angles relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0045] (4) Substantially parallel or orthogonal

[0046] The expressions "substantially orthogonal" and "approximately orthogonal" include situations where the angle formed by two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±5°. The expressions "substantially parallel" and "approximately parallel" include situations where the angle formed by two directions is 0°±10°, preferably 0°±7°, and more preferably 0°±5°. Furthermore, the abbreviations "orthogonal" or "parallel" in this specification may include situations where they are substantially orthogonal or substantially parallel.

[0047] A. Overview of Polarizing Film

[0048] Figure 11 is a schematic cross-sectional view of a polarizing plate including a polarizing film according to an embodiment of the present invention. The polarizing film 11 shown in the figure is composed of a resin film containing a dichroic organic pigment. The polarizing film 11 has a non-polarizing portion 15. In an embodiment of the present invention, the shape retention performance of the non-polarizing portion 15 after a wet heat test is excellent. In one embodiment, when the polarizing film is subjected to a wet heat test in an environment of 65°C and 90% RH for 24 hours, the rate of change of the periphery of the non-polarizing portion before and after the wet heat test is 3.0% or less. The rate of change of the periphery is preferably 2.5% or less, more preferably 1.5% or less, further preferably 1.0% or less, and particularly preferably 0.7% or less. The lower limit of the rate of change of the periphery is ideally zero, for example, it can be 0.1%. In another embodiment, when the polarizing film is subjected to a wet heat test in an environment of 65°C and 90% RH for 24 hours, the rate of change of the area of ​​the non-polarizing portion before and after the wet heat test is 5.0% or less. The rate of change in area is preferably 3.0% or less, more preferably 2.0% or less, further preferably 1.0% or less, and particularly preferably 0.5% or less. The lower limit of the rate of change in area is ideally zero, and may be, for example, 0.1%. According to the embodiments of the present invention, the shape of the non-polarizing portion can be well maintained from both the perspectives of the periphery and the area, thereby achieving a polarizing film with very high commercial value.

[0049] The rate of change of the periphery and area are calculated using the following formulas.

[0050] Peripheral change rate (%) = |(peripheral length after the test) - (peripheral length before the test) | / (peripheral length before the test) × 100

[0051] Area change rate (%) = |(area after test) - (area before test) | / (area before test) × 100

[0052] Circumference length (mm) and area (mm 2 ) are obtained by photographing the non-polarized portion using a photographing device and performing image processing on the obtained images.

[0053] The single transmittance Ts of the polarizing film 11 (excluding the non-polarizing portion 15) with respect to light with a wavelength of 380 nm to 780 nm is, for example, 38.0% or more, preferably 40.0% or more, and more preferably 40.5% or more. On the other hand, the single transmittance Ts can be, for example, 45.0% or less, and for example, 44.0% or less. The polarization degree P of the polarizing film 11 is, for example, 97.5% or more, preferably 98.0% or more, more preferably 98.5% or more, and further preferably 99.0% or more. On the other hand, the polarization degree P can be, for example, 99.95% or less, and for example, 99.90% or less.

[0054] The single-unit transmittance Ts of the non-polarizing portion 15 for light with a wavelength of 380 nm to 780 nm is, for example, 70.0% or greater, preferably 85.0% or greater, and more preferably 90.0% or greater. The polarization degree P of the non-polarizing portion 15 is, for example, 70.0% or less, preferably 25.0% or less, more preferably 3.0% or less, further preferably 2.0% or less, and particularly preferably 0.9% or less. It should be noted that the single-unit transmittance Ts can be calculated as a Y value measured using a 2-degree field of view (illuminant C) in accordance with JIS Z8701 and corrected for visibility.

[0055] When the polarizing film 11 is subjected to a damp heat test in an environment of 65°C and 90% RH for 24 hours, the absolute value of the change in the single transmittance ΔY of the non-polarizing portion 15 before and after the damp heat test is preferably 3.0 or less, more preferably 2.8 or less, further preferably 1.5 or less, particularly preferably 1.2 or less, and especially preferably 0.9 or less. The lower limit of the absolute value of ΔY is ideally zero, for example, it can be 0.1, and for example, it can be 0.2. According to an embodiment of the present invention, as described above, very excellent shape maintenance performance can be achieved for the non-polarizing portion, and the repigmentation of the non-polarizing portion can be suppressed in this way. As a result, a polarizing film with very high commercial value can be achieved and the function of the non-polarizing portion can be maintained for a long time.

[0056] When the polarizing film 11 is subjected to a damp heat test at 65°C and 90% RH for 24 hours, the absolute value of the change ΔL in the single-phase hue L value of the non-polarizing portion 15 in the Lab colorimetric system before and after the damp heat test is preferably 5.0 or less, more preferably 2.0 or less, further preferably 1.0 or less, and particularly preferably 0.5 or less. The lower limit of the absolute value of ΔL is preferably as small as possible, and can be, for example, 0.0.

[0057] The absolute value of the change Δa of the single-phase hue a value of the non-polarizing portion 15 in the Lab colorimetric system before and after the damp heat test is preferably 7.0 or less, more preferably 5.5 or less, further preferably 2.0 or less, and particularly preferably 0.5 or less. The lower limit of the absolute value of Δa is preferably as small as possible, and can be, for example, 0.0.

[0058] The single-phase hue L value and the single-phase hue a value of the Lab colorimetric system are measured, for example, by a spectrophotometer (typically, trade name "LPF-200", manufactured by Otsuka Electronics Co., Ltd.).

[0059] According to the embodiment of the present invention, as described above, it is possible to suppress the color reproduction in the non-polarization portion. As a result, the absolute values ​​of ΔL and Δa can also be small.

[0060] The absorbance of the non-polarizing portion 15 relative to each light of wavelengths 470nm, 560nm and 700nm is preferably 3.0 or less, more preferably 1.0 or less, further preferably 0.5 or less, and particularly preferably 0.2 or less. On the other hand, the absorbance of the non-polarizing portion 15 relative to the above-mentioned light is, for example, 0.001 or more, preferably 0.01 or more. If the absorbance of the non-polarizing portion is within this range, the light transmittance of the non-polarizing portion is good, and the function of the non-polarizing portion can be appropriately exerted. It should be noted that the absorbance of the non-polarizing portion is measured, for example, in accordance with JIS K0115.

[0061] The haze value of the non-polarizing portion 15 is preferably 30.0% or less, more preferably 10.0% or less, even more preferably 5.0% or less, particularly preferably 3.0% or less, especially preferably 2.0% or less, and most preferably 0.9% or less. The lower limit of the haze value of the non-polarizing portion 15 is preferably as low as possible, and can be, for example, 0.0%. When the haze value of the non-polarizing portion falls within this range, the light transmittance of the non-polarizing portion is excellent, and the non-polarizing portion can properly function.

[0062] The non-polarizing portion 15 is typically a laser-bleached portion. More specifically, the non-polarizing portion 15 is a bleached portion that is bleached by irradiation with laser light from a solid-state pulsed laser. With this configuration, the combination of a polarizing film comprising a resin film containing a dichroic organic pigment, as described above, allows for a polarizing film that exhibits excellent shape retention in the non-polarizing portion and suppresses color recoloration in the non-polarizing portion. As a result, a polarizing film with extremely high commercial value can be achieved that maintains the functionality of the non-polarizing portion for a long period of time.

[0063] The arrangement, shape, and size of the non-polarizing section 15 can be arbitrarily and appropriately set according to the application of the polarizing film 11 .

[0064] When the content of the dichroic organic pigment in the polarizing film 11 other than the non-polarizing portion 15 is set to 100% by mass, the content of the dichroic organic pigment in the non-polarizing portion 15 is preferably 10.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 1.5% by mass or less. The smaller the content of the dichroic organic pigment in the non-polarizing portion 15, the more preferable it is; for example, it can be 0.0% by mass. When the content of the dichroic organic pigment in the non-polarizing portion is within this range, the light transmittance of the non-polarizing portion can be improved, and color reproduction in the non-polarizing portion can be suppressed.

[0065] The thickness of the polarizing film 11 is, for example, 30 μm or less, preferably 12 μm or less, more preferably 10 μm or less, further preferably 8 μm or less, and particularly preferably 5 μm or less.

[0066] Hereinafter, the resin film and the dichroic organic dye will be described in detail.

[0067] B. Resin film

[0068] As a material of the resin film, any resin applicable to a polarizing film can be adopted. In one embodiment, the resin film includes a polyvinyl alcohol-based resin (hereinafter referred to as a PVA-based resin).

[0069] Examples of PVA resins include polyvinyl alcohol, acetal-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. The PVA resins may be used alone or in combination with two or more PVA resins having different modified species, modification rates, polymerization degrees, saponification degrees, and the like.

[0070] PVA resins typically include polyvinyl alcohol. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The content of polyvinyl alcohol in the PVA resin is, for example, 80% to 100% by mass, and preferably 88% to 95% by mass.

[0071] The PVA resin may contain acetoacetyl-modified polyvinyl alcohol in addition to polyvinyl alcohol. The content of the acetoacetyl-modified polyvinyl alcohol in the PVA resin is, for example, 5% to 20% by mass, and preferably 8% to 12% by mass.

[0072] The saponification degree of the PVA resin is generally 85 to 100 mol%, preferably 95.0 to 99.95 mol%, more preferably 99.0 to 99.93 mol%, and even more preferably 99.0 to 99.5 mol%. The saponification degree is measured, for example, in accordance with JIS K6726-1994. Using a PVA resin with such a saponification degree can achieve a thin polarizing film with excellent durability.

[0073] The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the intended purpose. The average degree of polymerization is, for example, 1000 or greater, preferably 1500 or greater, more preferably 2000 or greater, and even more preferably 3000 or greater. On the other hand, the average degree of polymerization is, for example, 10000 or less, preferably 6000 or less, and even more preferably 4300 or less. The average degree of polymerization is measured, for example, in accordance with JIS K6726-1994.

[0074] C. Dichroic organic pigments

[0075] As the dichroic organic pigment, any appropriate dye can be adopted. Examples of the dichroic organic pigment include acid dyes, direct dyes, basic dyes, salt-forming dyes, oil-soluble dyes, disperse dyes, reactive dyes, mordant dyes, vat dyes, sulfur dyes, their derivatives, and dyes obtained by laking them.

[0076] Dichroic organic pigments can be classified based on their chemical structure. Examples of dichroic organic dyes include azo dyes, disazo dyes, azomethine dyes (indoaniline dyes, indophenol dyes, etc.), dipyrromethene dyes, quinone dyes (benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, anthrapyridone dyes, etc.), carbonium dyes (diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, acridine dyes, etc.), quinoneimine dyes (oxazine dyes, thiazine dyes, etc.), azine dyes, polymethine dyes (oxonol dyes, merocyanine dyes, arylene dyes, styryl dyes, cyanine dyes, squarylium dyes, cronic acid dyes, etc.), quinophthalone dyes, phthalocyanine dyes, subphthalocyanine dyes, perindigo dyes, indigo dyes, thioindigo dyes, quinoline dyes, nitro dyes, nitroso dyes, rhodamine dyes, and metal complex dyes thereof. The dichroic organic pigments can be used alone or in combination.

[0077] Among the dichroic organic dyes, direct dyes are preferred, and azo dyes are more preferred. When the dichroic organic dye is an azo dye, color reproduction in the non-polarizing portion can be more stably suppressed.

[0078] In one embodiment, the dichroic organic dye includes one selected from an azo dye represented by the following formula (1), a salt of the azo dye, a chelate of the azo dye, or a mixture thereof.

[0079] [Chemical Formula 4]

[0080]

[0081] (In formula (1), X and Z each represent an atomic group represented by (2) to (13) below; Y represents an atomic group represented by (14) to (29) below; and m represents an integer from 0 to 6)

[0082] In the above formula (1), X and Z may be the same or different from each other. In addition, when m is 2 to 6, a plurality of Y may be the same or different from each other.

[0083] [Chemical Formula 5]

[0084]

[0085] (In formulas (2) to (13), A represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms that may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms that may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; n represents an integer from 0 to 5; o represents an integer from 0 to 4; p represents an integer from 0 to 3; q represents an integer from 0 to 2; and r represents 0 or 1.)

[0086] [Chemical Formula 6]

[0087]

[0088] (In formulas (14) to (29), A represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR or a hydrocarbon group having 1 to 12 carbon atoms which optionally contains a branched structure, a cyclic structure, a double bond or a triple bond; R, n, o, p, q and r are the same as those in the above formulas (2) to (13)).

[0089] Among the atomic groups represented by the above formulae (2) to (13) (i.e., X and Z in the above formula (1)), preferred examples include atomic groups represented by the above formula (2), the above formula (7), the above formula (8) and the above formula (13).

[0090] Among the atomic groups represented by the above formulae (14) to (29) (i.e., Y in the above formula (1)), preferred examples include atomic groups represented by the above formula (14), the above formula (22), the above formula (24), the above formula (28), and the above formula (29).

[0091] In the atomic groups represented by the above formulae (2) to (13), when a plurality of A's are included, the plurality of A's may be the same as or different from each other.

[0092] In the atomic groups represented by the above formulae (14) to (29), when a plurality of Bs are included, the plurality of Bs may be the same as or different from each other.

[0093] In the atomic groups represented by the above formulae (2) to (29), when a plurality of Rs are included, the plurality of Rs may be the same as or different from each other.

[0094] Examples of the salt of the azo dye include ammonium salts, alkaline earth metal salts, transition metal salts, and poor metal salts.

[0095] Examples of the chelate complex of azo dyes include chelates of metal elements and hydroxyl-containing azo dyes, chelates of alkoxy-containing azo dyes, and chelates of carboxyl-containing azo dyes.

[0096] Among the azo dyes, Direct Red 80, Direct Red 81, Direct Blue 2, Direct Yellow 8, and Direct Violet 9 are preferred.

[0097] D. Polarizer

[0098] like Figure 1 As shown, the polarizing films described in items A to C above can be suitably applied to polarizing plates. Like the polarizing film, the polarizing plate having the above polarizing film has excellent shape-maintaining performance of the non-polarizing portion, and the color reproduction of the non-polarizing portion is suppressed. The polarizing plate 10 shown in the example comprises the above polarizing film 11 and a protective layer 12 provided on at least one side of the polarizing film 11. In the example shown in the figure, the protective layer 12 is provided only on one side of the polarizing film 11. Although not shown, the protective layer may also be provided on both sides of the polarizing film 11. By providing the protective layer on both sides of the polarizing film, the shape-maintaining performance of the non-polarizing portion can be made more excellent. The protective layer may be attached to the polarizing film via an adhesive layer, or may be attached to the polarizing film via an adhesive layer.

[0099] The protective layer is formed by any appropriate film that can be used as a protective layer of a polarizing film. As a specific example of the material that becomes the main component of the film, cellulose resins such as triacetyl cellulose (TAC), polyesters such as polyethylene terephthalate (PET), polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, cycloolefin (COP), (meth) acrylic acid, acetate and other transparent resins can be cited. In addition, thermosetting resins or ultraviolet curing resins such as (meth) acrylic acid, carbamate, (meth) acrylic acid carbamate, epoxy, silicone can also be cited. In addition, glassy polymers such as siloxane polymers can also be cited. In addition, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01 / 37007) can also be used. It should be noted that "(meth) acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0100] Among materials for the protective layer, preferred materials are those without polyaromatic rings, more preferred materials primarily composed of aromatic rings, and even more preferred transparent materials that do not contain PET. When the protective layer is composed of a material without aromatic rings, damage to the protective layer caused by laser light can be suppressed even when the polarizing plate is subjected to the decolorization step described below, thereby preventing the protective layer from being burned.

[0101] The thickness of the protective layer is, for example, 1 mm or less, preferably 500 μm or less, more preferably 100 μm or less, further preferably 60 μm or less, and particularly preferably 30 μm or less. Meanwhile, the thickness of the protective layer is, for example, 1 μm or more, preferably 5 μm or more.

[0102] A surface treatment layer may be provided on the surface of the protective layer (the surface opposite to the polarizing film). Examples of the surface treatment layer include a hard coating layer, an anti-reflection layer, an anti-sticking layer, and an anti-glare layer. The thickness of the surface treatment layer may be any appropriate thickness depending on the intended purpose and the type of surface treatment layer. For example, the thickness of the surface treatment layer may be 1 μm to 10 μm.

[0103] E. Optical laminate

[0104] The polarizing films described in A to C and the polarizing plate described in D can be applied to optical laminates. Like polarizing films, optical laminates including the polarizing films have excellent shape retention properties in the non-polarizing portion and suppress color reproduction in the non-polarizing portion.

[0105] Figure 2 is included Figure 1 The optical laminate 100 shown in the figure includes the polarizer 10 described above, a retardation film 20 attached to the polarizer 10 via an adhesive layer 30, and an adhesive layer 40 located on the opposite side of the retardation film 20 from the polarizer 10.

[0106] The phase difference film 20 typically has an in-plane phase difference. The refractive index characteristics of the phase difference film 20 preferably show the relationship of nx>ny≥nz. In one embodiment, the phase difference film 20 can function as a λ / 4 plate. When the phase difference film 20 functions as a λ / 4 plate, the in-plane phase difference Re(550) of the phase difference film 20 is, for example, 100nm to 180nm, preferably 135nm to 155nm. The phase difference film 20 can be composed of one layer or more than two layers. The phase difference film is typically composed of a stretched film of a polyester carbonate resin film. If it is such a structure, the phase difference film can function as a protective layer of the polarizing film. As a result, when the polarizer has a protective layer on the side opposite to the phase difference film of the polarizing film as shown in the example, the shape maintenance performance of the non-polarizing portion can be made more excellent, similar to the case where a protective layer is provided on both sides of the polarizing film.

[0107] The angle formed between the absorption axis of the polarizing film 11 and the slow axis of the retardation film 20 is typically 40° to 50°, preferably 42° to 48°, more preferably 44° to 46°, and particularly preferably 45°. At such angles, the optical laminate can function as a circular polarizer.

[0108] The adhesive layer 30 and the adhesive layer 40 are each typically composed of a (meth)acrylic adhesive. The thickness of each of the adhesive layer 30 and the adhesive layer 40 can be, for example, 3.5 μm or more and 35 μm or less.

[0109] F. Method for manufacturing polarizing film

[0110] Next, one embodiment of a method for producing a polarizing film will be described.

[0111] One embodiment of the method for manufacturing a polarizing film includes: a dyeing step of dyeing the resin film described in item B above with the dichroic organic pigment described in item C above; a stretching step of stretching the resin film; and a bleaching step of irradiating a portion of the dyed and stretched resin film with a solid-state pulse laser to bleach the film to form a non-polarizing portion. The above-mentioned method for manufacturing a polarizing film may further include a swelling step, an insolubilization step, and / or a cleaning step. In the swelling step, the resin film before the dyeing step is typically immersed in a swelling bath (swelling liquid). In the cleaning step, the resin film is typically immersed in a cleaning bath after the stretching step and before the bleaching step.

[0112] In addition, below, the case where the resin film is the above-mentioned PVA-type resin film is described in detail.

[0113] F-1. PVA resin film

[0114] The PVA-based resin film before being subjected to the above-mentioned steps is used as a raw material film.

[0115] The raw material film may be a single-layer resin film or may be laminated on a thermoplastic resin base material.

[0116] Specific examples of single-layer resin films include hydrophilic polymer films such as PVA films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films, as well as polyene-based oriented films such as dehydrated PVA films and hydrochloric acid-degraded polyvinyl chloride films. When the raw material film is a single-layer resin film, its thickness is, for example, 20 to 65 μm, preferably 30 to 60 μm.

[0117] When the original film is laminated on the thermoplastic resin substrate, the original film may be a PVA-based resin film supported on the resin substrate, or may be a PVA-based resin layer formed by coating on the resin substrate.

[0118] When the raw material film is a PVA-based resin layer formed by coating on a resin substrate, a coating liquid containing the PVA-based resin is coated on a long strip of resin substrate by any appropriate method, and dried as needed, for example at above 50°C, thereby producing a laminate having a PVA-based resin layer and a resin substrate.

[0119] The constituent material of the resin substrate can be any appropriate material. As the constituent material of the resin substrate, representative examples include amorphous (uncrystallized) polyethylene terephthalate resins, and preferably amorphous (not easily crystallized) polyethylene terephthalate resins. As specific examples of amorphous polyethylene terephthalate resins, copolymers further comprising isophthalic acid as dicarboxylic acid and copolymers further comprising cyclohexanedimethanol as diols can be cited. Among the resin substrates, preferably amorphous isophthalic acid copolymerized polyethylene terephthalate film resin substrates can be cited.

[0120] The thickness of the resin substrate before stretching is, for example, 20 μm to 300 μm, or preferably 50 μm to 200 μm.

[0121] The surface of the resin substrate may be subjected to any appropriate surface treatment (such as corona treatment), or an easy-adhesion layer may be formed thereon, thereby improving the adhesion between the resin substrate and the PVA-based resin layer.

[0122] The coating liquid is typically a solution obtained by dissolving the above-mentioned PVA-based resin in a solvent.

[0123] The content of the PVA-based resin in the coating liquid is, for example, 3 to 20 parts by mass relative to 100 parts by mass of the solvent. With such a resin concentration, a uniform coating film that adheres closely to the resin substrate can be formed.

[0124] Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination. Among the solvents, water is preferred.

[0125] Iodide or sodium chloride (sometimes collectively referred to as halide) can be mixed into the coating liquid. Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The amount of halide mixed in the coating liquid is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of the PVA-based resin. By adding a halide to the coating liquid, a halide can be introduced into the resulting polarizing film. By introducing a halide into the polarizing film, the orientation of the PVA molecules in the polarizing film can be improved, thereby enabling a polarizing film having excellent optical properties (representatively, a combination of high polarization degree and high monomer transmittance) to be achieved.

[0126] The coating liquid may be mixed with additives. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyols such as ethylene glycol and glycerol. Examples of surfactants include nonionic surfactants.

[0127] The thickness of the PVA-based resin layer formed from such a coating liquid before stretching is, for example, 3 μm or more, preferably 5 μm or more, and for example, 40 μm or less, preferably 30 μm or less.

[0128] In addition, it is preferable that the laminate including the PVA-based resin layer and the resin substrate is subjected to an auxiliary stretching step in advance and is stretched in mid-air in the longitudinal direction.

[0129] The stretching temperature in the auxiliary stretching step is typically higher than the glass transition temperature (Tg) of the PVA resin, for example, higher than 95° C., preferably higher than 120° C. The stretching temperature in the auxiliary stretching step is typically lower than 150° C.

[0130] The stretching ratio of the laminate in the auxiliary stretching step is, for example, 2.1 times or more, preferably 2.3 times or more. On the other hand, the upper limit of the stretching ratio of the laminate in the auxiliary stretching step is typically 4 times.

[0131] The aerial stretching method in the auxiliary stretching step may be fixed-end stretching (for example, stretching using a tenter stretching machine) or free-end stretching (for example, uniaxial stretching by passing the laminate between rolls having different peripheral speeds).

[0132] F-2. Swelling process

[0133] The raw material film (the raw material film alone or the raw material film included in the laminate) is subjected to the swelling step before the dyeing step as needed.

[0134] In the swelling step, the raw film is typically immersed in a swelling solution (swelling bath). The swelling solution can be pure water or an aqueous boric acid solution. When the swelling solution is an aqueous boric acid solution (i.e., an insolubilizing solution), the swelling step also serves as the insolubilization step. The boric acid content in the insolubilizing solution is, for example, 1 to 10 parts by mass per 100 parts by mass of water.

[0135] The temperature of the swelling bath is, for example, 10° C. to 60° C., and preferably 20° C. to 50° C. The immersion time in the swelling step is, for example, 10 seconds to 200 seconds, and preferably 20 seconds to 60 seconds.

[0136] F-3. Dyeing process

[0137] In the dyeing step, the PVA resin film is dyed with a dyeing solution containing the dichroic organic dye. Specifically, the dyeing solution is brought into contact with the PVA resin film to allow the dichroic organic dye to adsorb.

[0138] The content of the dichroic organic pigment in the dyeing solution can be arbitrarily and appropriately set according to the temperature, time, pH, type of dichroic organic pigment, and stretch ratio during dyeing. The content of the dichroic organic pigment in the dyeing solution is, for example, 0.01% by mass to 30.0% by mass, preferably 0.10% by mass to 10.0% by mass.

[0139] In one embodiment, in the dyeing step, the PVA-based resin film is immersed in the dyeing bath.

[0140] The temperature of the dyeing bath is, for example, 10° C. to 80° C., and preferably 20° C. to 60° C. The immersion time (dyeing time) in the dyeing step is, for example, 5 seconds to 300 seconds, and preferably 10 seconds to 60 seconds.

[0141] The dye adsorption method in the dyeing step is not limited to the above-mentioned immersion. For example, the dyeing liquid may be applied to the PVA-based resin film, or the dyeing liquid may be sprayed onto the PVA-based resin film.

[0142] F-4. Stretching process

[0143] In one embodiment, in the stretching step, the dyed PVA resin film is stretched in the longitudinal direction in a boric acid aqueous solution as a stretching bath. When the PVA resin film is stretched in the boric acid aqueous solution, dissolution of the PVA resin film in the boric acid aqueous solution can be suppressed.

[0144] The stretching ratio in the stretching step varies depending on whether or not the raw material film is subjected to an auxiliary stretching step. When the raw material film is not subjected to an auxiliary stretching step (i.e., when the raw material film is a single-layer resin film or a resin film supported on a resin substrate), the stretching ratio in the stretching step is, for example, 4.5 to 7 times, preferably 5.0 to 6.5 times.

[0145] When the raw material film is subjected to an auxiliary stretching step (i.e., when the raw material film is a PVA-based resin layer formed by coating on a resin substrate), the stretching ratio in the stretching step is, for example, 1.5 to 4.0 times or less, preferably 1.5 to 3.0 times or less. Furthermore, the product of the stretching ratio in the auxiliary stretching step and the stretching ratio in the stretching step is, for example, 4.5 to 7.0 times, preferably 5.0 to 6.5 times.

[0146] By stretching at such a stretching ratio, extremely excellent polarization characteristics can be imparted to the polarizing film.

[0147] The content ratio of boric acid in the stretching liquid (boric acid aqueous solution) is, for example, 0.5 to 5.0 parts by mass, or preferably 0.7 to 3.0 parts by mass, relative to 100 parts by mass of water.

[0148] The temperature of the stretching bath is, for example, 40°C to 85°C, preferably 50°C to 65°C. When the temperature of the stretching bath is below the upper limit, even if the concentration of boric acid in the stretching bath is below the upper limit, dissolution of the PVA-based resin in the stretching bath can be stably suppressed. The immersion time in the stretching step is, for example, 15 seconds to 300 seconds.

[0149] F-5. Cleaning process

[0150] In the washing step, the PVA-based resin film after the stretching step is typically immersed in a washing bath. The washing bath is typically water.

[0151] The temperature of the cleaning bath is, for example, 0° C. to 40° C., and preferably 10° C. to 30° C. The immersion time in the cleaning step is, for example, 5 seconds to 200 seconds, and preferably 10 seconds to 60 seconds.

[0152] F-6. Drying and shrinking process

[0153] The PVA resin film after the washing step is preferably subjected to a drying and shrinking step before the decoloring step. In the drying and shrinking step, the PVA resin film is typically heated while being transported in the longitudinal direction. The drying and shrinking step is performed in a heating and drying section. The heating and drying section may employ a zone heating method in which the entire interior of the heating and drying section is heated, or a heated roller drying method in which the transport rollers are heated. Both methods are preferably used in the heating and drying section.

[0154] The internal temperature of the heating and drying section is, for example, 70° C. to 120° C., or preferably 80° C. to 100° C. The surface temperature of the heating roller is, for example, 60° C. to 100° C., or preferably 70° C. to 80° C.

[0155] By using a heating roller for drying, the PVA resin film (laminate) can be effectively prevented from curling due to heating, and a polarizing film with excellent appearance can be efficiently produced. In addition, in the drying and shrinking step, the PVA resin film shrinks in the width direction orthogonal to the longitudinal direction.

[0156] The shrinkage rate of the PVA-based resin film in the width direction during the drying and shrinking process is, for example, 2% or more, preferably 4% or more. If the shrinkage rate in the width direction is above this lower limit, the orientation of the PVA and PVA / dichroic organic pigments can be improved, and the polarization characteristics of the polarizing film (excluding the non-polarizing portion) can be improved. On the other hand, the shrinkage rate in the width direction is typically 10% or less, preferably 8% or less, and more preferably 6% or less. If the shrinkage rate in the width direction is below this upper limit, the polarizing film can be prevented from wrinkling and other appearance defects.

[0157] As described above, the polarizing film 11 before the formation of the non-polarizing portion 15 can be produced.

[0158] F-7. Decolorization (Non-Polarization Part Formation) Step

[0159] In the decolorization step, laser light from a solid-state pulse laser is irradiated onto any appropriate portion of the polarizing film 11, depending on the purpose and application. In the decolorization step, the target of laser irradiation may be the polarizing film 11 alone, the polarizing plate 10 including the polarizing film 11, or the optical laminate 100 including the polarizing plate 10. Specifically, the polarizing film may be laminated with the aforementioned layers and / or films (e.g., a protective layer, a retardation film, an adhesive layer) after forming a non-polarizing portion on the polarizing film, or the polarizing film may be laminated with the aforementioned layers and / or films after forming a non-polarizing portion on the polarizing film.

[0160] When the polarizing plate 10 or the optical laminate 100 is subjected to the decoloring step, the laser beam is irradiated from the viewing side relative to the polarizing film 11 (in the illustrated example, the side opposite to the polarizing film 11 of the protective layer 12 ).

[0161] In one embodiment, the laser beam is moved at a predetermined processing speed to irradiate the entire portion of the polarizing film 11 where the non-polarizing portion is to be formed.

[0162] In this way, by irradiating a polarizing film composed of a resin film containing a dichroic organic pigment with a predetermined laser beam, a non-polarizing portion can be formed that exhibits excellent light transmittance, excellent shape retention, and suppressed color reproduction. Furthermore, by adjusting the laser beam irradiation conditions, the color tone of the formed non-polarizing portion can be appropriately adjusted.

[0163] Examples of the solid pulse laser include Yb laser, YAG laser, and YVO 4 laser, and preferably Yb laser is used.

[0164] The power of the solid pulse laser is, for example, 0.1 W to 100 W, and preferably 3.0 W to 20.0 W. When the power of the solid pulse laser is within such a range, the haze of the non-polarized portion can be stably reduced.

[0165] The gain of the solid pulse laser is, for example, 20% to 80%, and preferably 30% to 50%.

[0166] The pulse width of the laser is, for example, 220 fs to 30 ps, ​​preferably 270 fs to 20 ps. The wavelength of the laser is, for example, greater than 300 nm, preferably greater than 355 nm, and more preferably greater than 500 nm. On the other hand, the wavelength of the laser is, for example, less than 1070 nm, preferably less than 550 nm. If the pulse width and wavelength of the laser are within such a range, the desired portion of the polarizing film can be smoothly bleached, and damage to the resin material (representatively, PVA-based resin) contained in the polarizing film due to the laser can be suppressed. As a result, the haze of the non-polarized portion can be reduced.

[0167] The frequency of the laser light is preferably 0.1 kHz to 200 kHz, more preferably 0.2 kHz to 100 kHz, further preferably 0.3 kHz to 80 kHz, and particularly preferably 0.4 kHz to 70 kHz.

[0168] The pulse energy of the laser is, for example, 0.1 μJ to 40 μJ, preferably 0.2 μJ to 30 μJ, more preferably 0.3 μJ to 20 μJ, further preferably 0.4 μJ to 10 μJ, and particularly preferably 0.5 μJ to 5 μJ.

[0169] When the frequency and / or pulse energy of the laser light is within such a range, the haze of the non-polarized portion can be further stably reduced.

[0170] In one embodiment, the pulse energy of the laser and the frequency of the laser satisfy the following formulas (I) and (II).

[0171] y≤0.0524x 2 -2.7475x+48.325(I)

[0172] y≥0.6547x -0.365 (II)

[0173] (In formulas (I) and (II), y represents the frequency of the laser (kHz), and x represents the pulse energy of the laser (μJ).)

[0174] When the pulse energy of the laser and the frequency of the laser satisfy the above-mentioned formulae (I) and (II), excellent transmittance can be imparted to the non-polarized portion, and the haze of the non-polarized portion can be significantly reduced.

[0175] The laser processing speed is, for example, 1.0×10 -2 cm / s~100.0cm / s, preferably 5.0×10 -2 cm / s to 50.0 cm / s, more preferably 0.1 cm / s to 25.0 cm / s.

[0176] The ratio of the frequency of the laser light to the processing speed of the laser light (frequency (kHz) / processing speed (cm / s)) is, for example, 0.001 to 200, or preferably 0.1 to 5.0.

[0177] The laser light preferably includes polarized light that is substantially parallel to the absorption axis of the polarizing film 11. If the laser light includes such polarized light, a desired portion of the polarizing film can be decolorized more smoothly, and a non-polarized portion can be formed efficiently.

[0178] By subjecting a polarizing film composed of a resin film containing a dichroic organic dye to a decoloring step under such conditions, a non-polarizing portion having excellent light transmittance and shape retention and suppressed color reproduction can be formed, while also suppressing damage to the polarizing film itself.

[0179] As described above, a polarizing film having a non-polarizing portion can be produced. It should be noted that, when a polarizer is provided in the decolorization step, a polarizer having a non-polarizing portion can be produced, and when an optical laminate is provided in the decolorization step, an optical laminate having a non-polarizing portion can be produced.

[0180] [Example]

[0181] The present invention is described in detail below by way of examples, but the present invention is not limited to these examples. The measurement methods and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0182] (1) Change rate of non-polarized part

[0183] The non-polarizing portion of the polarizing film obtained in the examples and comparative examples was photographed using a photographic device (manufactured by EPSON, product name "GT-S650") (resolution 300 dpi). The obtained images were binarized to determine the perimeter length (mm) and area (mm) before the test. 2 ). Furthermore, the polarizing films, polarizers and optical laminates obtained in the examples and comparative examples were subjected to a wet heat test at 65°C and 90% RH for 12 hours or 24 hours, and the perimeter length (mm) and area (mm) after the test were calculated in the same manner as above. 2 ). Use the following formulas to calculate the rate of change of the perimeter and area, respectively. The selection of code for the above processing is arbitrary. For example, the above processing can be performed by various codes including C++, Python, machine language, etc.

[0184] Peripheral change rate (%) = |(peripheral length after the test) - (peripheral length before the test) | / (peripheral length before the test) × 100

[0185] Area change rate (%) = |(area after test) - (area before test) | / (area before test) × 100

[0186] Based on the change rates obtained as described above, the shape retention performance was evaluated according to the following criteria.

[0187] <Periphery>

[0188] 5 (Excellent): Change rate is less than 1%

[0189] 4 (Good): Change rate is more than 1% and less than 3%

[0190] 3 (Permissible): The change rate is more than 3% and less than 5%.

[0191] 2 (Insufficient): The change rate is more than 5% and less than 15%

[0192] 1 (bad): Change rate exceeds 15%

[0193] <Area>

[0194] 5 (Excellent): Change rate is less than 0.5%

[0195] 4 (Good): Change rate is more than 0.5% and less than 2%

[0196] 3 (Permissible): The change rate is more than 2% and less than 5%.

[0197] 2 (Insufficient): The change rate is more than 5% and less than 15%

[0198] 1 (bad): Change rate exceeds 15%

[0199] (2) Change in single transmittance ΔY

[0200] The single transmittance Ts of the non-polarizing portion of the polarizing film obtained in the Examples and Comparative Examples was measured using a spectrophotometer (trade name: U-4100, manufactured by Hitachi High-Technologies Corporation). It should be noted that the single transmittance Ts is a Y value measured using a 2-degree field of view (light source C) of JIS Z8701 and corrected for visibility. Furthermore, the polarizing films, polarizers, and optical laminates obtained in the Examples and Comparative Examples were subjected to a wet heat test at 65°C and 90% RH for 12 hours or 24 hours, and the single transmittance of the non-polarizing portion was measured in the same manner as described above. The difference obtained by subtracting the value before the test from the value after the test was calculated as ΔY.

[0201] (3) Change in single-phase hue L value ΔL, change in single-phase hue a value Δa, and change in single-phase hue b value Δb

[0202] The L value, a value, and b value of the non-polarizing portion of the polarizing films obtained in Examples and Comparative Examples were measured using a spectrophotometer (trade name "LPF-200," manufactured by Otsuka Electronics Co., Ltd.). Furthermore, the polarizing films, polarizers, and optical laminates obtained in Examples and Comparative Examples were subjected to a damp heat test at 65°C and 90% RH for 12 or 24 hours. The L value, a value, and b value of the non-polarizing portion were then measured in the same manner as described above. The difference between the pre-test value and the post-test value was calculated as ΔL, Δa, and Δb.

[0203] (4) Pigment content ratio in the non-polarized area (pigment residue)

[0204] The absorbance of the polarizing films (excluding the non-polarizing portion) and the non-polarizing portion obtained in the Examples and Comparative Examples was measured using a spectrophotometer (trade name: U-4100, manufactured by Hitachi High-Technologies Corporation). Furthermore, the dichroic content (residual pigment content) in the non-polarizing portion was calculated using the following formula (II).

[0205] Residual pigment amount (mass %) = (absorbance of non-polarizing portion / absorbance outside non-polarizing portion) × content ratio of dichroic substance in the portion outside non-polarizing portion of polarizing film (mass %) (II)

[0206] [Manufacturing Example 1: Preparation of a Polarizing Film Containing an Organic Dye]

[0207] As a thermoplastic resin substrate, a long amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) having a Tg of approximately 75° C. was used, and one surface of the resin substrate was subjected to a corona treatment.

[0208] 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1, and the resultant was dissolved in water to prepare a PVA aqueous solution (coating liquid).

[0209] The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.

[0210] The obtained laminate was uniaxially stretched to 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).

[0211] Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilization treatment).

[0212] Next, the laminate was immersed in a dye bath at a temperature of 30°C for 60 seconds (dyeing treatment). The dye bath was prepared by dissolving Direct Yellow 8, Direct Blue 2, and Direct Violet 9 in water at a mass ratio of 6:9:2. The concentration of the dye was adjusted so that the single-unit transmittance Ts of the resulting polarizing film reached the desired value.

[0213] Next, the laminate was immersed in a crosslinking bath (boric acid aqueous solution prepared by adding 3 parts by weight of potassium iodide and 5 parts by weight of boric acid to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).

[0214] Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, it is uniaxially stretched (underwater stretching treatment) in the longitudinal direction (long side direction) between rollers with different peripheral speeds so that the total stretching ratio becomes 5.5 times.

[0215] Then, the laminate was immersed in a cleaning bath (an aqueous solution containing 4 parts by weight of potassium iodide per 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).

[0216] Thereafter, the laminate was dried in an oven maintained at approximately 90° C. and brought into contact with a heated roll made of SUS whose surface temperature was maintained at approximately 75° C. (drying shrinkage treatment).

[0217] Thus, a polarizing film having a thickness of about 5 μm was formed on the resin substrate, thereby obtaining a laminate having a structure of resin substrate / dye-containing polarizing film. The single-piece transmittance of the obtained polarizing film was 41%.

[0218] [Manufacturing Example 2: Preparation of Iodine-Containing Polarizing Film]

[0219] A laminated body having a structure of a resin substrate and an iodine-containing polarizing film (approximately 5 μm thick) was obtained by the same procedure as in Production Example 1, except that an iodine aqueous solution (liquid temperature 30°C) prepared by dissolving iodine and potassium iodide in water at a weight ratio of 1:7 was used as the dyeing bath. The concentration of the dyeing bath (iodine aqueous solution) was adjusted so that the single-element transmittance Ts of the resulting polarizing film reached the desired value. The single-element transmittance Ts of the resulting polarizing film was 41%.

[0220] [Manufacturing Example 3: Preparation of Phase Difference Film]

[0221] In a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux cooler controlled at 100° C., 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19×100 parts by mass of calcium acetate monohydrate as a catalyst were added. -2 Mass parts (6.78×10 - 5mol). After the reactor was purged with nitrogen, it was heated with a heat medium and stirring began when the internal temperature reached 100°C. Forty minutes after the start of the temperature increase, the internal temperature was brought to 220°C and maintained at this temperature. Simultaneously, the pressure was reduced, reaching 13.3 kPa over 90 minutes after reaching 220°C. Phenol vapor, a by-product of the polymerization reaction, was introduced into a 100°C reflux cooler, allowing a small amount of monomer components contained in the phenol vapor to return to the reactor. Uncondensed phenol vapor was introduced into a 45°C condenser and recovered. Nitrogen was introduced into the first reactor to temporarily return the pressure to atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature and pressure in the second reactor were increased and reduced, reaching an internal temperature of 240°C and a pressure of 0.2 kPa over 50 minutes. Polymerization was then continued until the specified stirring power was reached. Once the specified power was reached, nitrogen was introduced into the reactor to repressurize it. The resulting polyester carbonate resin was extruded into water, and strands were cut to obtain pellets.

[0222] The resulting polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours and then formed into a long strip of resin film using a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a cooling roller (set temperature: 120-130°C), and a winder. The resulting long strip of resin film was longitudinally stretched at 140°C at the free end to obtain a retardation film with a thickness of 40 μm. The refractive index characteristics of the retardation film showed a relationship of nx>ny=nz (positive A plate).

[0223] [Example 1]

[0224] A solid-state pulsed laser was used to irradiate a predetermined portion of the polarizing film of the laminate obtained in Production Example 1 with green laser light from the resin substrate side to form a non-polarizing portion (a roughly circular portion with a diameter of approximately 10 mm). The laser irradiation conditions were as follows. The resulting non-polarizing portion had a single-unit transmittance of 88% and a residual pigment content of 1.0% by mass.

[0225] Laser: Yb laser

[0226] Oscillator: Light Conversion, product name "PHAROS"

[0227] Wavelength: 513nm

[0228] Power: 10W@50kHz

[0229] Width: 290fs~15ps

[0230] Scanning method: electronic scanner

[0231] Focal length: 163mm

[0232] The polarizing film having a non-polarizing portion obtained as described above was subjected to the evaluations of (1) to (3) above. Specifically, the polarizing film side of a laminate comprising a resin substrate / pigment-containing polarizing film was bonded to a glass plate via an adhesive, and then the resin substrate was peeled off to obtain a laminate having a structure of pigment-containing polarizing film / adhesive / glass plate. This laminate was used as a test sample and the tests of (1) to (3) above were performed. The results are shown in Table 1.

[0233] [Example 2]

[0234] A non-polarizing portion was formed at a predetermined position on the polarizing film of the laminate obtained in Manufacturing Example 1, in the same manner as in Example 1. Next, the retardation film of Manufacturing Example 3 was bonded to the polarizing film side of the resin substrate / pigment-containing polarizing film laminate via an adhesive. Furthermore, a glass plate was bonded to the retardation film via an adhesive, and the resin substrate was then peeled off, resulting in a laminate having a structure of pigment-containing polarizing film / retardation film / adhesive / glass plate. This laminate served as a test sample and was subjected to the same test as in Example 1. The results are shown in Table 1.

[0235] [Example 3]

[0236] The same operation as in Example 2 was performed to obtain a laminate having a structure of a resin substrate / a pigment-containing polarizing film / a phase difference film. The resin substrate was peeled off from the laminate, and a (meth) acrylic film (manufactured by Toyo Kopan Co., Ltd., product name "RV20", thickness 20 μm) was attached to the peeling surface as a protective layer via an ultraviolet curing adhesive. Furthermore, a glass plate was attached to the phase difference film of the laminate via an adhesive to obtain a laminate having a structure of a protective layer / a pigment-containing polarizing film / a phase difference film / adhesive / a glass plate. The laminate was used as a test sample and the same test as in Example 1 was performed. The results are shown in Table 1.

[0237] [Comparative Example 1]

[0238] A laminate having a structure consisting of protective layer / iodine-containing polarizing film / retardation film / adhesive / glass plate was obtained in the same manner as in Example 3, except that the iodine-containing polarizing film of Production Example 2 was used instead of the pigment-containing polarizing film of Production Example 1. This laminate served as a test sample and was tested in the same manner as in Example 1. The results are shown in Table 1. The resulting non-polarizing portion had a single-unit transmittance of 70%.

[0239] [Comparative Example 2]

[0240] A laminated body having a structure consisting of an iodine-containing polarizing film / retardation film / adhesive / glass plate was obtained by the same procedures as in Example 2, except that the iodine-containing polarizing film of Example 2 was used in place of the pigment-containing polarizing film of Example 1, and that the non-polarizing portion was formed by alkali treatment instead of laser irradiation. This laminated body was used as a test sample and the same tests as in Example 1 were performed. The results are shown in Table 1. The resulting non-polarizing portion had a single-unit transmittance of 90%.

[0241] The alkali treatment is as follows. An ester resin film with an adhesive having through-holes formed at predetermined locations is bonded to the surface of the polarizing film of the laminate obtained in Manufacturing Example 2. The resulting laminate is immersed in a 1 mol / L (1N) aqueous sodium hydroxide solution for 180 seconds. This bleaching of the ester resin film at locations corresponding to the through-holes in the polarizing film creates a non-polarizing portion. After the alkali treatment, the ester resin film is peeled off and removed.

[0242] [Comparative Example 3]

[0243] A laminate having a structure consisting of a protective layer, an iodine-containing polarizing film, a retardation film, an adhesive, and a glass plate was obtained by the same procedures as in Example 3, except that the iodine-containing polarizing film of Example 2 was used instead of the pigment-containing polarizing film of Example 1, and that the non-polarizing portion was formed by alkali treatment instead of laser irradiation. This laminate served as a test sample and was tested in the same manner as in Example 1. The results are shown in Table 1. The alkali treatment was performed in the same manner as in Comparative Example 2.

[0244] [Comparative Example 4]

[0245] The same operation as in Comparative Example 2 was carried out except that the acid treatment was further performed after the alkali treatment to obtain a laminate having a structure of an iodine-containing polarizing film / phase difference film / adhesive / glass plate. This laminate was used as a test sample and the same test as in Example 1 was carried out. The results are shown in Table 1. It should be noted that the acid treatment was carried out by further immersing the laminate subjected to the alkali treatment in 1 mol / L (1N) hydrochloric acid for 60 seconds. After the acid treatment, the ester resin film was peeled off and removed. The monomer transmittance of the non-polarizing portion formed was 90%.

[0246] [Comparative Example 5]

[0247] A laminate having a structure consisting of a protective layer, an iodine-containing polarizing film, a retardation film, an adhesive, and a glass plate was obtained in the same manner as in Comparative Example 3, except that an acid treatment was performed after the alkali treatment. This laminate was used as a test sample and the same test as in Example 1 was performed. The results are shown in Table 1. Furthermore, the acid treatment was performed in the same manner as in Comparative Example 4.

[0248] [Comparative Example 6]

[0249] A laminate having a structure consisting of a protective layer, a pigment-containing polarizing film, a retardation film, an adhesive, and a glass plate was obtained in the same manner as in Example 3, except that the non-polarizing portion was formed by alkali treatment and acid treatment instead of laser irradiation. This laminate was used as a test sample and the same tests as in Example 1 were performed. The results are shown in Table 1. It should be noted that the alkali treatment was performed in the same manner as in Comparative Example 2, and the acid treatment was performed in the same manner as in Comparative Example 4.

[0250]

[0251] [evaluate]

[0252] As shown in Table 1, according to the examples of the present invention, by irradiating a polarizing film composed of a resin film containing a dichroic organic pigment to achieve decolorization by laser irradiation, and then forming a non-polarizing portion on the polarizing film, a polarizing film with excellent shape retention and suppressed discoloration of the non-polarizing portion can be achieved. Comparative Example 1 shows that when the non-polarizing portion is formed by irradiating a polarizing film containing iodine with laser irradiation, the shape of the non-polarizing portion is maintained to an acceptable level, but discoloration of the non-polarizing portion is significant. Comparative Examples 2 to 5 show that when the non-polarizing portion is formed by alkali treatment, discoloration over time can be suppressed, but shape retention is insufficient.

[0253] [Industrial Applicability]

[0254] The polarizing film, polarizing plate, and optical laminate according to the embodiment of the present invention can be suitably used in image display devices (typically, liquid crystal display devices and organic EL display devices).

Claims

1. A polarizing film comprising a resin film containing a dichroic organic pigment and having a non-polarizing portion, When the polarizing film was subjected to a humidity test in an environment of 65° C. and 90% RH for 24 hours, the change rate of the periphery of the non-polarizing portion before and after the humidity test was 3.0% or less.

2. A polarizing film comprising a resin film containing a dichroic organic pigment and having a non-polarizing portion, When the polarizing film was subjected to a humidity test under an environment of 65° C. and 90% RH for 24 hours, the rate of change in the area of ​​the non-polarizing portion before and after the humidity test was 5.0% or less.

3. The polarizing film according to claim 1 or 2, wherein The resin film includes a polyvinyl alcohol-based resin, The dichroic organic dye comprises one selected from the group consisting of an azo dye represented by the following formula (1), a salt of the azo dye, a chelate of the azo dye, or a mixture thereof. [Chemical Formula 1] In formula (1), X and Z represent the atomic groups shown in (2) to (13) below; Y represents the atomic groups shown in (14) to (29) below; m represents an integer from 0 to 6, [Chemical Formula 2] In formulas (2) to (13), A represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms which may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms which may contain a linear structure, a branched structure, a cyclic structure, a double bond, or a triple bond; n represents an integer from 0 to 5; o represents an integer from 0 to 4; p represents an integer from 0 to 3; q represents an integer from 0 to 2; r represents 0 or 1, [Chemical Formula 3] In formulas (14) to (29), B represents H, OH, OR1, SO3H, NH2, NR2, NO2, COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms that may contain a branched structure, a cyclic structure, a double bond, or a triple bond; R, n, o, p, q, and r are the same as those in formulas (2) to (13) above.

4. The polarizing film according to claim 1 or 2, wherein When the content of the dichroic organic dye in the polarizing film excluding the non-polarizing portion is 100% by mass, the content of the dichroic organic dye in the non-polarizing portion is 3.0% by mass or less.

5. The polarizing film according to claim 1 or 2, wherein The haze value of the non-polarizing portion is 5.0% or less.

6. The polarizing film according to claim 1 or 2, wherein When the polarizing film is subjected to a humidity test under an environment of 65° C. and 90% RH for 24 hours, the absolute value of the change in the single transmittance of the non-polarizing portion before and after the humidity test is 3.0 or less.

7. The polarizing film according to claim 1 or 2, wherein The non-polarized portion is a laser decolorization portion. 8 . A polarizing plate comprising the polarizing film according to claim 1 or 2 and a protective layer provided on at least one side of the polarizing film.

9. The polarizing plate according to claim 8, wherein Protective layers are provided on both sides of the polarizing film.

10. An optical laminate comprising the polarizing film according to claim 1 or 2, a protective layer provided on one side of the polarizing film, and a retardation film provided on the other side of the polarizing film. The in-plane retardation Re(550) of the retardation film is 100 nm to 180 nm. The angle formed between the absorption axis direction of the polarizing film and the slow axis direction of the retardation film is 40° to 50°.

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