Polarization film, polarizer, and optical laminate

Abstract

To provide a polarization film having a non-polarization part, excellent in a shape maintenance performance of the non-polarization part, while preventing the non-polarization part from re-coloring.SOLUTION: A polarization film is composed of a resin film including a dichroic organic pigment, and includes a non-polarization part. In one embodiment, when the polarization film is put in a wet heat test standing under a 65°C and 90%RH environment for 24 hours, a change rate in the polarization film is 3.0% or less with regard to a circumference of the non-polarization part before and after the wet heat test. In another embodiment, when the polarization film is put in the wet heat test standing under a 65°C and 90%RH environment for 24 hours, a change rate in the polarization film is 5.0% or less with regard to an area of the non-polarization part before and after the wet heat test.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. Such image display devices typically use polarizing films containing iodine. Furthermore, to accommodate the increasing variety and high functionality of image display devices, polarizing films with partial polarization properties are in demand. One known method for producing such polarizing films is to bleach a portion of the polarizing film by irradiating it with laser light containing light with a wavelength of at least 1,500 nm or less to form a non-polarizing portion (see, for example, Patent Document 1). Another known method is to bleach a portion of the polarizing film by contacting it with a basic substance to form a non-polarizing portion (see, for example, Patent Document 2). However, while the shape of the non-polarizing portion of the polarizing film produced by the method described in Patent Document 1 can be maintained, the non-polarizing portion (bleached portion) may recolor over time. Although the non-polarizing portion of the polarizing film produced by the method described in Patent Document 2 can be prevented from recoloring over time, its shape retention is insufficient. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-081482 [Patent Document 2] Special Publication No. 2015-525725 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned problems of the conventional art, and a main object of the present invention is to provide a polarizing film which has a non-polarizing portion, which has excellent shape-retention performance of the non-polarizing portion, and in which color recovery of the non-polarizing portion is suppressed. [Means for solving the problem]

[0005] [1] A polarizing film according to one embodiment of the present invention is made of a resin film containing a dichroic organic dye and has a non-polarizing portion. When the polarizing film is subjected to a moist heat test in which the polarizing film is left standing in an environment of 65°C and 90% RH for 24 hours, the change in the outer circumference of the non-polarizing portion before and after the moist heat test is 3.0% or less. [2] Another embodiment of the polarizing film of the present invention is made of a resin film containing a dichroic organic dye, has a non-polarizing portion, and when the polarizing film is subjected to a moist heat test in which it is left standing in 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 moist heat test is 5.0% or less. [3] In the above [1] or [2], the resin film contains a polyvinyl alcohol resin, and the dichroic organic dye contains 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: [ka] (In formula (1), X and Z each represent an atomic group shown in (2) to (13) below; Y represents an atomic group shown in (14) to (29) below; and m represents an integer of 0 to 6.) [ka] (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 have a linear, branched, or cyclic structure, or a double or triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms which may have a linear, branched, or cyclic structure, or a double or triple bond; n represents an integer of 0 to 5; o represents an integer of 0 to 4; p represents an integer of 0 to 3; q represents an integer of 0 to 2; and r represents 0 or 1.) [ka] (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 which may have 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] In any of [1] to [3] above, the polarizing film has a dichroic organic dye content in the non-polarizing portion of the polarizing film of 3.0% by mass or less, when the dichroic organic dye content in the polarizing film excluding the non-polarizing portion is taken as 100% by mass. [5] In any one of the above [1] to [4], the haze value of the non-polarizing portion is 5.0% or less. [6] In any of [1] to [5] above, when the polarizing film is subjected to a moist heat test in which it is left standing in an environment of 65°C and 90% RH for 24 hours, the absolute value of the change in the single-unit transmittance of the non-polarizing portion before and after the moist heat test is 3.0 or less. [7] In any one of the above items [1] to [6], the non-polarizing portion is a laser bleaching portion. [8] According to another aspect of the present invention, there is provided a polarizing plate comprising 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. [9] In the above [8], the polarizing plate has protective layers on both sides of the polarizing film.

[10] According to yet another aspect of the present invention, there is provided an optical laminate. The optical laminate includes 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 the angle between the absorption axis direction of the polarizing film and the slow axis direction of the retardation film is 40° to 50°. [Effects of the Invention]

[0006] According to an embodiment of the present invention, a polarizing film can be realized which has a non-polarizing portion, which has excellent shape-retaining properties, and in which color recovery of the non-polarizing portion is suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a polarizing plate including a polarizing film according to an embodiment of the present invention. [Figure 2] 2 is a schematic cross-sectional view of an optical laminate including the polarizing plate of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0008] Representative embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. The drawings are schematic for ease of understanding, and differ from the actual lengths, widths, thicknesses, ratios of each layer, etc.

[0009] (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d, where d (nm) is the thickness of the layer (film). (3)Angle When angles are referred to herein, the angles include both clockwise and counterclockwise angles relative to a reference direction, so for example, "45°" means ±45°. (4) Substantially parallel or perpendicular The expressions "substantially perpendicular" and "approximately perpendicular" include the case where the angle between two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±5°. The expressions "substantially parallel" and "approximately parallel" include the case where the angle between two directions is 0°±10°, preferably 0°±7°, and more preferably 0°±5°. Furthermore, when simply referring to "orthogonal" or "parallel" in this specification, this can include the state of being substantially perpendicular or substantially parallel.

[0010] A. Overview of polarizing film FIG. 1 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 made of a resin film containing a dichroic organic dye. The polarizing film 11 has a non-polarizing portion 15. In an embodiment of the present invention, the non-polarizing portion 15 exhibits excellent shape retention after a moist heat test. In one embodiment, when the polarizing film is subjected to a moist heat test in which the film is left standing at 65°C and 90% RH for 24 hours, the change in the outer periphery of the non-polarizing portion before and after the moist heat test is 3.0% or less. The change in the outer periphery is preferably 2.5% or less, more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.7% or less. The lower limit of the change in the outer periphery is ideally zero, and may be, for example, 0.1%. In another embodiment, when the polarizing film is subjected to a moist heat test in which the film is left standing at 65°C and 90% RH for 24 hours, the change in the area of ​​the non-polarizing portion before and after the moist 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, even more 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, for example, 0.1%. According to the embodiment of the present invention, the shape of the non-polarizing portion is well maintained in terms of both the outer periphery and the area, making it possible to realize a polarizing film with extremely high commercial value. The rate of change of the circumference and area can be calculated using the following formulas: Percent change in circumference (%) = |(perimeter length after test) - (perimeter length before test)| / (perimeter length before test) x 100 Area change rate (%) = |(area after test) - (area before test)| / (area before test) × 100 Circumference length (mm) and area (mm 2 ) can be obtained by capturing an image of the unpolarized portion with an imaging device and processing the resulting image.

[0011] The polarizing film 11 (excluding the non-polarizing portion 15) has a single transmittance Ts of, for example, 38.0% or more, preferably 40.0% or more, and more preferably 40.5% or more for light with wavelengths of 380 nm to 780 nm. Meanwhile, the single transmittance Ts may be, for example, 45.0% or less, or 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 even more preferably 99.0% or more. Meanwhile, the polarization degree P may be, for example, 99.95% or less, or for example, 99.90% or less. The non-polarizing section 15 has a single transmittance Ts for light with wavelengths of 380 nm to 780 nm of, for example, 70.0% or more, preferably 85.0% or more, and more preferably 90.0% or more. The non-polarizing section 15 has a polarization degree P of, for example, 70.0% or less, preferably 25.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, and particularly preferably 0.9% or less. The single transmittance Ts can be calculated as a Y value corrected for visibility using, for example, a 2-degree visual field (C light source) according to JIS Z8701.

[0012] When the polarizing film 11 is subjected to a humidity and heat test in which the film is left standing for 24 hours in an environment of 65°C and 90% RH, the absolute value of the change in the single transmittance of the non-polarizing portion 15, ΔY, before and after the humidity and heat test is preferably 3.0 or less, more preferably 2.8 or less, even more preferably 1.5 or less, particularly preferably 1.2 or less, and particularly preferably 0.9 or less. The lower limit of the absolute value of ΔY is ideally zero, and may be, for example, 0.1 or 0.2. According to embodiments of the present invention, the non-polarizing portion exhibits excellent shape retention as described above, and color recovery of the non-polarizing portion can be suppressed. As a result, a polarizing film with high commercial value and capable of maintaining the functionality of the non-polarizing portion for a long period of time can be realized.

[0013] When polarizing film 11 is subjected to a moist heat test in which it is left standing for 24 hours in an environment of 65°C and 90% RH, the absolute value of the change ΔL in the single-phase hue L value of the Lab color system of non-polarizing section 15 before and after the moist heat test is preferably 5.0 or less, more preferably 2.0 or less, even more 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. The absolute value of the change Δa in the single-phase hue a value of the Lab color system of the non-polarized section 15 before and after the above-mentioned moist heat test is preferably 7.0 or less, more preferably 5.5 or less, even more 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. The single-phase hue L value and the single-phase hue a value of the Lab color system are measured, for example, by a spectrophotometer (typically, the trade name "LPF-200" manufactured by Otsuka Electronics Co., Ltd.). According to the embodiment of the present invention, the color recovery of the non-polarizing portion can be suppressed as described above, and as a result, the absolute values ​​of ΔL and Δa can also be small.

[0014] The absorbance of the non-polarized portion 15 is preferably 3.0 or less, more preferably 1.0 or less, even more preferably 0.5 or less, and particularly preferably 0.2 or less, for light having wavelengths of 470 nm, 560 nm, and 700 nm. Meanwhile, the absorbance of the non-polarized portion 15 for the above-mentioned light is, for example, 0.001 or more, preferably 0.01 or more. If the absorbance of the non-polarized portion is within this range, the light transmittance of the non-polarized portion is good, and the non-polarized portion can properly function. The absorbance of the non-polarized portion is measured, for example, in accordance with JIS K 0115.

[0015] The haze value of the non-polarizing section 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, particularly preferably 2.0% or less, and most preferably 0.9% or less. The lower limit of the haze value of the non-polarizing section 15 is preferably as small as possible, and can be, for example, 0.0%. If the haze value of the non-polarizing section is within this range, the light transmittance of the non-polarizing section is good, and the non-polarizing section can perform its function appropriately.

[0016] The non-polarizing section 15 is typically a laser-bleached section. More specifically, the non-polarizing section 15 is a bleached section bleached by irradiation with laser light from a solid-state pulsed laser. With this configuration, in combination with the fact that the polarizing film is made of a resin film containing a dichroic organic dye as described above, it is possible to realize a polarizing film that has excellent shape retention performance of the non-polarizing section and in which color recovery of the non-polarizing section is suppressed. As a result, it is possible to realize a polarizing film that has very high commercial value and in which the functionality of the non-polarizing section can be maintained for a long period of time.

[0017] The arrangement, shape, and size of the non-polarizing portion 15 can be arbitrarily and appropriately set depending on the application of the polarizing film 11 .

[0018] The content of the dichroic organic dye in the non-polarizing sections 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, when the content of the dichroic organic dye in the polarizing film 11 excluding the non-polarizing sections 15 is taken as 100% by mass. The smaller the content of the dichroic organic dye in the non-polarizing sections 15, the better, and it can be, for example, 0.0% by mass. If the content of the dichroic organic dye in the non-polarizing sections is within this range, the light transmittance of the non-polarizing sections can be improved and color recovery of the non-polarizing sections can be suppressed.

[0019] 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. On the other hand, the thickness of the polarizing film 11 is, for example, 1 μm or more, preferably 3 μm or more.

[0020] The resin film and the dichroic organic dye will be described in detail below.

[0021] B. Resin film Any resin that can be used for a polarizing film can be used as the material for the resin film. In one embodiment, the resin film contains a polyvinyl alcohol-based resin (hereinafter referred to as a PVA-based resin). Examples of PVA resins include polyvinyl alcohol, acetal-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. A PVA resin may be used alone, or two or more PVA resins with different types of modification, modification rates, polymerization degrees, and saponification degrees may be used in combination.

[0022] The PVA resin typically contains polyvinyl alcohol, which is 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.

[0023] The PVA resin may contain acetoacetyl-modified polyvinyl alcohol in addition to polyvinyl alcohol. The content of acetoacetyl-modified polyvinyl alcohol in the PVA resin is, for example, 5% to 20% by mass, and preferably 8% to 12% by mass.

[0024] The saponification degree of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%, and even more preferably 99.0 mol% to 99.5 mol%. The saponification degree is measured, for example, in accordance with JIS K 6726-1994. By using a PVA resin with such a saponification degree, a thin polarizing film with excellent durability can be realized.

[0025] The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is, for example, 1,000 or more, preferably 1,500 or more, more preferably 2,000 or more, and even more preferably 3,000 or more. On the other hand, the average degree of polymerization is, for example, 10,000 or less, preferably 6,000 or less, and even more preferably 4,300 or less. The average degree of polymerization is measured, for example, in accordance with JIS K 6726-1994.

[0026] C. Dichroic organic dye Any appropriate dye can be used as the dichroic organic dye, including, for example, acid dyes, direct dyes, basic dyes, salt-forming dyes, oil-soluble dyes, disperse dyes, reactive dyes, mordant dyes, vat dyes, sulfur dyes, derivatives thereof, and lake dyes thereof.

[0027] Dichroic organic dyes 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.), and the like. Dichroic organic dyes include azine dyes, polymethine dyes (oxonol dyes, merocyanine dyes, arylidene dyes, styryl dyes, cyanine dyes, squarylium dyes, croconium dyes, etc.), quinophthalone dyes, phthalocyanine dyes, subphthalocyanine dyes, perinone dyes, indigo dyes, thioindigo dyes, quinoline dyes, nitro dyes, nitroso dyes, rhodamine dyes, and metal complex dyes thereof. The dichroic organic dyes can be used alone or in combination.

[0028] Of the dichroic organic dyes, direct dyes are preferred, and azo dyes are more preferred. When the dichroic organic dye is an azo dye, color recovery in the non-polarized portion can be more stably suppressed. In one embodiment, the dichroic organic dye 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: [ka] (In formula (1), X and Z each represent an atomic group shown in (2) to (13) below; Y represents an atomic group shown in (14) to (29) below; and m represents an integer of 0 to 6.) In the above formula (1), X and Z may be the same or different from each other. When m is 2 to 6, multiple Ys may be the same or different from each other.

[0029] [ka] (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 have a linear, branched, or cyclic structure, or may have a double bond or a triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms which may have a linear, branched, or cyclic structure, or may have a double bond or a triple bond; n represents an integer of 0 to 5; o represents an integer of 0 to 4; p represents an integer of 0 to 3; q represents an integer of 0 to 2; and r represents 0 or 1.)

[0030] [ka] (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 may have 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.)

[0031] Of the atomic groups represented by the formulae (2) to (13) above (i.e., X and Z in the formula (1) above), preferred examples include atomic groups represented by the formulae (2), (7), (8) and (13) above. Among the atomic groups represented by the above formulas (14) to (29) (i.e., Y in the above formula (1)), preferred examples include atomic groups represented by the above formulas (14), (22), (24), (28), and (29). When the atomic group represented by the above formulas (2) to (13) contains a plurality of As, the plurality of As may be the same or different from one another. When the atomic group represented by the above formulas (14) to (29) contains a plurality of Bs, the Bs may be the same or different from one another. When the atomic group represented by the above formulas (2) to (29) contains a plurality of Rs, the Rs may be the same or different from one another.

[0032] Examples of salts of azo dyes include ammonium salts, alkaline earth metal salts, transition metal salts, and poor metal salts. Examples of the chelate of an azo dye include a chelate of a metal element and a hydroxyl-containing azo dye, a chelate of an alkoxy-containing azo dye, and a chelate of a carboxyl-containing azo dye.

[0033] Of the azo dyes, Direct Red 80, Direct Red 81, Direct Blue 2, Direct Yellow 8, and Direct Violet 9 are preferred.

[0034] D. Polarizing plate As shown in FIG. 1 , the polarizing films described in sections A to C above can be suitably applied to polarizing plates. A polarizing plate including the above polarizing film, like the polarizing film, has excellent shape retention properties for the non-polarizing portion and suppresses color recovery in the non-polarizing portion. The illustrated polarizing plate 10 includes the above polarizing film 11 and a protective layer 12 provided on at least one side of the polarizing film 11. In the illustrated example, the protective layer 12 is provided on only one side of the polarizing film 11. Although not shown, protective layers may be provided on both sides of the polarizing film 11. Providing protective layers on both sides of the polarizing film can further improve the shape retention properties of the non-polarizing portion. The protective layer may be attached to the polarizing film via a pressure-sensitive adhesive layer or an adhesive layer.

[0035] The protective layer is formed of any suitable film that can be used as a protective layer for a polarizing film. Specific examples of materials that can serve as the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins such as polyethylene terephthalate (PET), transparent resins such as polyvinyl alcohol-based resins, polycarbonates-based resins, polyamides-based resins, polyimides-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, polynorbornene-based resins, polyolefin-based resins, cycloolefin (COP)-based resins, (meth)acrylic resins, and acetate-based resins. Other examples include thermosetting or ultraviolet-curable resins such as (meth)acrylic resins, urethane-based resins, (meth)acrylic urethane-based resins, epoxy resins, and silicone-based resins. Other examples include glassy polymers such as siloxane-based polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) may also be used. Note that "(meth)acrylic" refers to acrylic and / or methacrylic resins. Among the materials for the protective layer, a material having no polyaromatic ring is preferred, a material having no aromatic ring as a main component is more preferred, and a transparent material not containing PET is even more preferred. When the protective layer is made of a material having no aromatic ring, damage to the protective layer caused by laser light can be suppressed and scorching of the protective layer can be suppressed even when the polarizing plate is subjected to a bleaching step described later.

[0036] The thickness of the protective layer is, for example, 1 mm or less, preferably 500 μm or less, more preferably 100 μm or less, even more preferably 60 μm or less, and particularly preferably 30 μm or less, while the thickness of the protective layer is, for example, 1 μm or more, preferably 5 μm or more.

[0037] 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 coat treatment layer, an anti-reflection treatment layer, an anti-sticking treatment layer, and an anti-glare treatment layer. The thickness of the surface treatment layer may be any appropriate thickness depending on the purpose and the type of the surface treatment layer. The thickness of the surface treatment layer may be, for example, 1 μm to 10 μm.

[0038] E. Optical laminate The polarizing film described above in items A to C and the polarizing plate described above in item D can be applied to an optical laminate. The optical laminate including the polarizing film described above has excellent shape retention performance of the non-polarizing portion, and color recovery of the non-polarizing portion is suppressed, similar to the polarizing film. Fig. 2 is a schematic cross-sectional view of an optical laminate including the polarizing plate of Fig. 1. The optical laminate 100 of the illustrated example includes the above-mentioned polarizing plate 10, a retardation film 20 attached to the polarizing plate 10 via a pressure-sensitive adhesive layer 30, and a pressure-sensitive adhesive layer 40 located on the opposite side of the retardation film 20 from the polarizing plate 10.

[0039] The retardation film 20 typically has an in-plane retardation. The refractive index characteristics of the retardation film 20 preferably satisfy the relationship nx>ny≧nz. In one embodiment, the retardation film 20 can function as a λ / 4 plate. When the retardation film 20 functions as a λ / 4 plate, the in-plane retardation Re(550) of the retardation film 20 is, for example, 100 nm to 180 nm, preferably 135 nm to 155 nm. The retardation film 20 may be composed of one layer or two or more layers. The retardation film is typically composed of a stretched polyester carbonate resin film. With this configuration, the retardation film can function as a protective layer for the polarizing film. As a result, when the polarizing plate has a protective layer on the side of the polarizing film opposite the retardation film as in the illustrated example, the shape retention performance of the non-polarizing portion can be improved, similar to when protective layers are provided on both sides of the polarizing film.

[0040] The angle formed by the absorption axis direction of the polarizing film 11 and the slow axis direction of the retardation film 20 is typically 40° to 50°, preferably 42° to 48°, more preferably 44° to 46°, and particularly preferably 45°. With such an angle, the optical laminate can function as a circular polarizing plate.

[0041] Each of the pressure-sensitive adhesive layer 30 and the pressure-sensitive adhesive layer 40 is typically made of a (meth)acrylic pressure-sensitive adhesive. The thickness of each of the pressure-sensitive adhesive layer 30 and the pressure-sensitive adhesive layer 40 may be, for example, 3.5 μm or more and 35 μm or less.

[0042] F. Polarizing Film Manufacturing Method Next, one embodiment of a method for producing a polarizing film will be described. One embodiment of the method for producing a polarizing film includes a dyeing step of dyeing the resin film described in Section B above with the dichroic organic dye described in Section 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 laser light from a solid-state pulse laser to bleach it and form a non-polarizing portion. The method for producing a polarizing film may further include a swelling step, an insolubilizing step, and / or a washing step. In the swelling step, the resin film before the dyeing step is typically immersed in a swelling bath (swelling liquid). In the washing step, the resin film is typically immersed in a washing bath after the stretching step and before the bleaching step. In the following, a detailed description will be given of the case where the resin film is the above-mentioned PVA-based resin film.

[0043] F-1. PVA resin film The PVA resin film before the above-mentioned steps are carried out is referred to as a raw film. The raw film may be a single-layer resin film, or may be laminated on a thermoplastic resin substrate.

[0044] 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, and polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films. When the raw film is a single-layer resin film, its thickness is, for example, 20 μm to 65 μm, and preferably 30 μm to 60 μm.

[0045] When the raw film is laminated on a thermoplastic resin substrate, the raw film may be a PVA-based resin film supported on the resin substrate, or a PVA-based resin layer formed by coating on the resin substrate.

[0046] When the raw film is a PVA-based resin layer formed by coating on a resin substrate, a coating liquid containing a PVA-based resin is applied to a long resin substrate by any appropriate method, and if necessary, dried at a temperature of 50°C or higher, for example, to produce a laminate comprising a PVA-based resin layer and a resin substrate.

[0047] Any appropriate material may be used as the constituent material of the resin substrate. A typical constituent material of the resin substrate is an amorphous (uncrystallized) polyethylene terephthalate resin, preferably an amorphous (hard to crystallize) polyethylene terephthalate resin. Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid as a dicarboxylic acid and copolymers further containing cyclohexanedimethanol as a glycol. Among the resin substrates, an amorphous isophthalic copolymerized polyethylene terephthalate film resin substrate is preferred. The thickness of the resin substrate before stretching is, for example, 20 μm to 300 μm, and preferably 50 μm to 200 μm. The surface of the resin substrate may be subjected to any appropriate surface treatment (for example, corona treatment), or an easy-adhesion layer may be formed on the surface, which can improve the adhesion between the resin substrate and the PVA-based resin layer.

[0048] The coating liquid is typically a solution in which the above-mentioned PVA resin is dissolved in a solvent. The content of the PVA 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 tightly to the resin substrate can be formed.

[0049] Examples of solvents include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination. Of the solvents, water is preferred.

[0050] The coating solution may contain iodide or sodium chloride (sometimes collectively referred to as a halide). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The amount of halide contained in the coating solution is preferably 5 to 20 parts by weight, and more preferably 10 to 15 parts by weight, per 100 parts by weight of the PVA resin. By incorporating a halide into the coating solution, the halide can be introduced into the resulting polarizing film. By introducing a halide into the polarizing film, the orientation of PVA molecules in the polarizing film can be improved, resulting in a polarizing film with excellent optical properties (typically, both a high polarization degree and a high single-unit transmittance).

[0051] The coating liquid may contain additives. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Examples of surfactants include nonionic surfactants.

[0052] 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.

[0053] Furthermore, the laminate comprising the PVA-based resin layer and the resin substrate is preferably subjected to a supplementary stretching step in advance to be stretched in the air in the longitudinal direction. The stretching temperature in the auxiliary stretching step is typically equal to or higher than the glass transition temperature (Tg) of the PVA resin, for example, equal to or higher than 95° C., and preferably equal to or higher than 120° C. The stretching temperature in the auxiliary stretching step is typically equal to or lower than 150° C. 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, while the upper limit of the stretching ratio of the laminate in the auxiliary stretching step is typically 4 times. The in-air stretching method in the auxiliary stretching step may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxially stretching the laminate by passing it between rolls with different peripheral speeds).

[0054] F-2. Swelling process The raw film (raw film alone or raw film included in a laminate) is subjected to the swelling step as required before the dyeing step. In the swelling step, the raw film is typically immersed in a swelling liquid (swelling bath). The swelling liquid may be pure water or a boric acid aqueous solution. When the swelling liquid is a boric acid aqueous solution (i.e., an insolubilizing liquid), the swelling step also serves as an insolubilizing step. The content of boric acid in the insolubilizing liquid is, for example, 1 to 10 parts by mass per 100 parts by mass of water. The temperature of the swelling bath is, for example, 10 to 60° C., and preferably 20 to 50° C. The immersion time in the swelling step is, for example, 10 to 200 seconds, and preferably 20 to 60 seconds.

[0055] F-3. Dyeing process In the dyeing step, the PVA-based resin film is dyed with a dye solution containing the dichroic organic dye. Specifically, the dye solution is brought into contact with the PVA-based resin film to adsorb the dichroic organic dye. The content of the dichroic organic dye in the dye solution can be arbitrarily and appropriately set depending on the dyeing temperature, time, pH, type of dichroic organic dye, and stretching ratio. The content of the dichroic organic dye in the dye solution is, for example, 0.01% by mass to 30.0% by mass, and preferably 0.10% by mass to 10.0% by mass.

[0056] In one embodiment, in the dyeing step, the PVA-based resin film is immersed in the dye bath. The temperature of the dye bath is, for example, 10 to 80° C., and preferably 20 to 60° C. The immersion time (dyeing time) in the dyeing step is, for example, 5 to 300 seconds, and preferably 10 to 60 seconds. The method for adsorbing the dye in the dyeing step is not limited to the above-mentioned immersion method. For example, the dye solution may be applied to the PVA-based resin film, or the dye solution may be sprayed onto the PVA-based resin film.

[0057] F-4. Stretching process In one embodiment, in the stretching step, the PVA-based resin film after the dyeing step is stretched in the longitudinal direction in a boric acid aqueous solution as a stretching bath. Stretching the PVA-based resin film in the boric acid aqueous solution can prevent the PVA-based resin film from dissolving in the boric acid aqueous solution. The stretching ratio in the stretching step varies depending on whether or not an auxiliary stretching step is performed on the raw film. When the auxiliary stretching step is not performed on the raw film (i.e., when the raw 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, and preferably 5.0 to 6.5 times. When the auxiliary stretching step is performed on the raw film (i.e., when the raw 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, and preferably 1.5 to 3.0 times or less. 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, and preferably 5.0 to 6.5 times. By stretching at the above-mentioned stretching ratio, the polarizing film can be endowed with extremely excellent polarizing properties.

[0058] The content of boric acid in the drawing liquid (boric acid aqueous solution) is, for example, 0.5 to 5.0 parts by mass, and preferably 0.7 to 3.0 parts by mass, relative to 100 parts by mass of water. The temperature of the stretching bath is, for example, 40°C to 85°C, and preferably 50°C to 65°C. If the temperature of the stretching bath is not more than the above upper limit, the PVA resin can be stably prevented from dissolving in the stretching bath even if the concentration of boric acid in the stretching bath is not more than the above upper limit. The immersion time in the stretching step is, for example, 15 seconds to 300 seconds.

[0059] F-5. Cleaning process In the washing step, the PVA resin film after the stretching step is typically immersed in a washing bath, which is typically water. 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.

[0060] F-6. Drying shrinkage process The PVA resin film after the washing step is preferably subjected to a drying and shrinking step before the decolorizing 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 carried out in a heating and drying section. The heating and drying section may be a zone heating type in which the entire interior of the heating and drying section is heated, or a heating roll drying type in which the transport rolls are heated. Preferably, both types of heating and drying sections are used. The internal temperature of the heating and drying section is, for example, 70 to 120°C, and preferably 80 to 100°C. The surface temperature of the heating roll is, for example, 60 to 100°C, and preferably 70 to 80°C. Drying using a heated roll efficiently prevents the PVA resin film (laminate) from curling due to heat, allowing for efficient production of a polarizing film with excellent appearance. In addition, in the drying shrinkage step, the PVA resin film shrinks in the width direction perpendicular to the longitudinal direction. The shrinkage ratio in the width direction of the PVA-based resin film in the drying shrinkage step is, for example, 2% or more, preferably 4% or more. If the shrinkage ratio in the width direction is equal to or greater than this lower limit, the orientation of the PVA and the PVA / each dichroic organic dye can be improved, and the polarization properties of the polarizing film (excluding the non-polarizing portion) can be improved. On the other hand, the shrinkage ratio in the width direction is typically 10% or less, preferably 8% or less, and more preferably 6% or less. If the shrinkage ratio in the width direction is equal to or less than this upper limit, the occurrence of defects in appearance such as wrinkles in the polarizing film can be suppressed.

[0061] In this manner, the polarizing film 11 before the non-polarizing portions 15 are formed can be produced.

[0062] F-7. Decolorization (formation of non-polarized part) process In the bleaching step, any appropriate portion of the polarizing film 11 depending on the purpose and application is irradiated with laser light from a solid-state pulse laser. In the bleaching step, the target of irradiation with laser light may be only the polarizing film 11, a polarizing plate 10 including the polarizing film 11, or an optical laminate 100 including the polarizing plate 10. That is, a non-polarizing portion may be formed in the polarizing film, and then the polarizing film and the above-mentioned layer and / or film (e.g., a protective layer, a retardation film, a pressure-sensitive adhesive layer) may be laminated thereon, or a non-polarizing portion may be formed in the polarizing film after the polarizing film and the above-mentioned layer and / or film are laminated thereon. When the polarizing plate 10 or the optical laminate 100 is subjected to the bleaching step, the laser light is irradiated onto the polarizing film 11 from the viewing side (in the illustrated example, the side of the protective layer 12 opposite to the polarizing film 11). In one embodiment, the laser light is moved at a predetermined processing speed to irradiate the entire area of ​​the polarizing film 11 where the non-polarizing portion is to be formed. In this way, by irradiating a polarizing film made of a resin film containing a dichroic organic dye with a predetermined laser beam, a non-polarizing portion having excellent light transmittance, excellent shape retention, and reduced color recovery can be formed. Furthermore, by adjusting the irradiation conditions of the laser beam, the color tone of the formed non-polarizing portion can be appropriately adjusted.

[0063] Examples of solid-state pulse lasers include Yb lasers, YAG lasers, and YVO4 lasers, with Yb lasers being preferred. The output of the solid-state pulse laser is, for example, 0.1 W to 100 W, and preferably 3.0 W to 20.0 W. If the output of the solid-state pulse laser is in this range, the haze in the non-polarized portion can be stably reduced. The attenuation of the solid-state pulse laser is, for example, 20% to 80%, and preferably 30% to 50%.

[0064] The pulse width of the laser beam is, for example, 220 fs to 30 ps, ​​and preferably 270 fs to 20 ps. The wavelength of the laser beam is, for example, 300 nm or more, preferably 355 nm or more, and more preferably 500 nm or more. On the other hand, the wavelength of the laser beam is, for example, 1070 nm or less, and preferably 550 nm or less. When the pulse width and wavelength of the laser beam are within these ranges, desired portions of the polarizing film can be smoothly bleached, and damage to the resin material (typically a PVA-based resin) contained in the polarizing film by the laser beam can be suppressed. As a result, the haze in the non-polarized portion can be reduced.

[0065] The frequency of the laser light is preferably 0.1 kHz to 200 kHz, more preferably 0.2 kHz to 100 kHz, even more preferably 0.3 kHz to 80 kHz, and particularly preferably 0.4 kHz to 70 kHz. The pulse energy of the laser light is, for example, 0.1 μJ to 40 μJ, preferably 0.2 μJ to 30 μJ, more preferably 0.3 μJ to 20 μJ, still more preferably 0.4 μJ to 10 μJ, and particularly preferably 0.5 μJ to 5 μJ. If the frequency and / or pulse energy of the laser light is within this range, the haze in the non-polarized portion can be reduced more stably.

[0066] In one embodiment, the pulse energy of the laser beam and the frequency of the laser beam satisfy the following formulas (I) and (II). y≦0.0524x 2-2.7475x+48.325 (I) y≧0.6547x ―0.365 (II) (In formulas (I) and (II), y represents the frequency (kHz) of the laser light, and x represents the pulse energy (μJ) of the laser light.) If the pulse energy and frequency of the laser beam satisfy the above formulas (I) and (II), excellent transmittance can be imparted to the non-polarized portion, and haze in the non-polarized portion can be significantly reduced.

[0067] The processing speed of the laser beam is, for example, 1.0 × 10 -2 cm / s to 100.0 cm / s, preferably 5.0 × 10 -2 The speed is preferably from 0.1 cm / s to 50.0 cm / s, and more preferably from 0.1 cm / s to 25.0 cm / s. 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, and preferably 0.1 to 5.0.

[0068] The laser light preferably contains polarized light that is approximately parallel to the absorption axis of the polarizing film 11. When the laser light contains such polarized light, desired portions of the polarizing film can be bleached more smoothly, and non-polarized portions can be formed efficiently.

[0069] When the bleaching process is carried out under these conditions on a polarizing film made of a resin film containing a dichroic organic dye, a non-polarizing portion can be formed that has excellent light transmittance, excellent shape retention performance, and reduced recoloring, while also reducing damage to the polarizing film itself.

[0070] In this manner, a polarizing film having a non-polarizing portion can be produced. When a polarizing plate is subjected to the bleaching step, a polarizing plate having a non-polarizing portion can be produced, and when an optical laminate is subjected to the bleaching step, an optical laminate having a non-polarizing portion can be produced. [Example]

[0071] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Measurement and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0072] (1) Rate of change of non-polarized part The non-polarized portions of the polarizing films obtained in the Examples and Comparative Examples were photographed (resolution: 300 dpi) using an imaging device (manufactured by EPSON, product name "GT-S650"). The obtained images were binarized to obtain the pre-test outer perimeter length (mm) and pre-test area (mm). 2 Furthermore, the polarizing films, polarizing plates, and optical laminates obtained in the examples and comparative examples were subjected to a moist heat test in which they were left standing in an environment of 65°C and 90% RH for 12 hours or 24 hours, and then the peripheral length (mm) and area (mm) after the test were measured in the same manner as above. 2 ) was calculated. The rates of change of the perimeter and area were calculated using the following equations. The code for the above process can be selected arbitrarily. For example, the above process can be executed using various codes including C++, Python, machine language, etc. Percent change in circumference (%) = |(perimeter length after test) - (perimeter length before test)| / (perimeter length before test) x 100 Area change rate (%) = |(area after test) - (area before test)| / (area before test) × 100 From the rate of change obtained as described above, the shape retention performance was evaluated according to the following criteria. <Outer periphery> 5 (Excellent): Change rate is 1% or less 4 (Good): Change rate is over 1% and 3% or less 3 (Acceptable): Change rate is more than 3% and less than 5% 2 (Insufficient): Change rate is more than 5% and less than 15% 1 (bad): Change rate is over 15% <Area> 5 (Excellent): Change rate is 0.5% or less 4 (Good): Change rate is over 0.5% and 2% or less 3 (Acceptable): Change rate is more than 2% and less than 5% 2 (Insufficient): Change rate is more than 5% and less than 15% 1 (bad): Change rate is over 15%

[0073] (2) Change in single unit transmittance ΔY The single transmittance Ts of the non-polarized portion of the polarizing film obtained in the Examples and Comparative Examples was measured using a spectrophotometer (product name: U-4100, manufactured by Hitachi High-Tech Corporation). The single transmittance Ts was measured using a 2-degree visual field (C light source) according to JIS Z8701, and is the Y value corrected for luminosity. Furthermore, the polarizing films, polarizing plates, and optical laminates obtained in the Examples and Comparative Examples were subjected to a moist heat test in which they were left standing in an environment of 65°C and 90% RH for 12 or 24 hours, and then the single transmittance of the non-polarized portion was measured in the same manner as above. The difference obtained by subtracting the value before the test from the value after the test was calculated as ΔY.

[0074] (3) The change in the single-phase hue L value, ΔL, the change in the single-phase hue a value, Δa, and the change in the single-phase hue b value, Δb The L, a, and b values ​​of the non-polarized portions of the polarizing films obtained in the Examples and Comparative Examples were measured using a spectrophotometer (product name "LPF-200", manufactured by Otsuka Electronics Co., Ltd.). Furthermore, the polarizing films, polarizing plates, and optical laminates obtained in the Examples and Comparative Examples were subjected to a moist heat test in which they were left standing in an environment of 65°C and 90% RH for 12 or 24 hours, and then the L, a, and b values ​​of the non-polarized portions were measured in the same manner as above. The differences obtained by subtracting the values ​​before the test from the values ​​after the test were calculated as ΔL, Δa, and Δb.

[0075] (4) Pigment content in the non-polarized area (amount of residual pigment) 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 (product name: U-4100, manufactured by Hitachi High-Technologies Corporation). Furthermore, the content of the dichroic material (amount of residual dye) in the non-polarizing portion was calculated using the following formula (II): Residual dye amount (mass%) = (absorbance of non-polarized area / absorbance of non-polarized area) × content of dichroic substance in non-polarized area of ​​polarizing film (mass%) (II)

[0076] [Production Example 1: Preparation of organic dye-containing polarizing film] A long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin made 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 "GOHSEFFIMER") in a 9:1 ratio, to which 13 parts by weight of potassium iodide was added, in water. The above PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained 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 (insolubilizing treatment). The laminate was then immersed in a dye bath at 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 in a mass ratio of 6:9:2. The dye concentrations were adjusted so that the resulting polarizing film would have a desired single-piece transmittance Ts. Next, the laminate was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). Thereafter, the laminate was dried in an oven maintained at about 90°C, and brought into contact with a heated roll made of SUS whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this way, a polarizing film with a thickness of about 5 μm was formed on the resin substrate, and a laminate having a resin substrate / dye-containing polarizing film structure was obtained. The single transmittance of the obtained polarizing film was 41%.

[0077] [Production Example 2: Preparation of iodine-containing polarizing film] A laminate having a resin substrate / iodine-containing polarizing film (thickness: approximately 5 μm) structure was obtained in the same manner 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 dye bath. The concentration of the dye bath (iodine aqueous solution) was adjusted so that the single-piece transmittance Ts of the resulting polarizing film would be the desired value. The single-piece transmittance of the resulting polarizing film was 41%.

[0078] [Production Example 3: Preparation of Retardation Film] A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was charged with 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 × 10-2 parts by mass (6.78 × 10-5 mol) of calcium acetate monohydrate as a catalyst. After purging the reactor with nitrogen under reduced pressure, the reactor was heated with a heat medium, and stirring was started when the internal temperature reached 100°C. The internal temperature reached 220°C 40 minutes after the start of the temperature increase, and while maintaining this temperature, pressure reduction was initiated. The pressure was reduced to 13.3 kPa within 90 minutes after reaching 220°C. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and the small amount of monomer components contained in the phenol vapor was returned to the reactor. Uncondensed phenol vapor was collected by introducing nitrogen into the first reactor and restoring the pressure to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa within 50 minutes. Polymerization was then allowed to proceed until the specified stirring power was reached. Once the specified power was reached, nitrogen was introduced into the reactor to restore the pressure. The resulting polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets. The resulting polyester carbonate resin pellets were vacuum-dried at 80°C for 5 hours, and then a long resin film was produced using a film-making device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder temperature setting: 250°C), a T-die (width 200 mm, temperature setting: 250°C), a chill roll (temperature setting: 120-130°C), and a winder. The resulting long resin film was longitudinally stretched at its free end at 140°C to obtain a 40 μm-thick retardation film. The refractive index characteristics of the retardation film showed the relationship nx>ny=nz (positive A plate).

[0079] [Example 1] A non-polarized portion (approximately circular with a diameter of approximately 10 mm) was formed at a predetermined position on the polarizing film of the laminate obtained in Production Example 1 by irradiating it with green laser light from a solid-state pulse laser from the resin substrate side. The laser light irradiation conditions were as follows. The formed non-polarized portion had a single transmittance of 88% and a residual dye amount of 1.0% by mass. Laser light: Yb laser Oscillator: LIGHT CONVERSION, product name "PHAROS" Wavelength: 513nm Output: 10W@50kHz Pulse width: 290fs~15ps Scanning method: Galvano scanner Focal length: 163mm

[0080] The polarizing film having a non-polarizing portion obtained as described above was subjected to the evaluations (1) to (3) above. Specifically, the polarizing film side of a laminate of a resin substrate / dye-containing polarizing film was attached to a glass plate via an adhesive, and then the resin substrate was peeled off to obtain a laminate having a structure of dye-containing polarizing film / adhesive / glass plate. The laminate was used as a test sample and the tests (1) to (3) above were performed. The results are shown in Table 1.

[0081] [Example 2] A non-polarizing portion was formed at a predetermined position on the polarizing film of the laminate obtained in Production Example 1 in the same manner as in Example 1. Next, the retardation film of Production Example 3 was attached to the polarizing film side of the resin substrate / dye-containing polarizing film laminate via an adhesive, and a glass plate was further attached to the retardation film via an adhesive, after which the resin substrate was peeled off, to obtain a laminate having a structure of dye-containing polarizing film / retardation film / adhesive / glass plate. Using this laminate as a test sample, tests similar to those in Example 1 were carried out. The results are shown in Table 1.

[0082] [Example 3] A laminate having a structure of resin substrate / dye-containing polarizing film / retardation film was obtained in the same manner as in Example 2. The resin substrate was peeled from this laminate, and a (meth)acrylic film (manufactured by Toyo Kohan Co., Ltd., product name "RV20", thickness 20 μm) was attached as a protective layer to the peeled surface via a UV-curable adhesive. Furthermore, a glass plate was attached to the retardation film of the laminate via an adhesive, to obtain a laminate having a structure of protective layer / dye-containing polarizing film / retardation film / adhesive / glass plate. Using this laminate as a test sample, the same tests as in Example 1 were carried out. The results are shown in Table 1.

[0083] [Comparative Example 1] A laminate having a structure 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 dye-containing polarizing film of Production Example 1. Using this laminate as a test sample, the same tests as in Example 1 were carried out. The results are shown in Table 1. The single transmittance of the formed non-polarizing portion was 70%.

[0084] Comparative Example 2 A laminate having a structure of iodine-containing polarizing film / retardation film / adhesive / glass plate was obtained in the same manner as in Example 2, except that the iodine-containing polarizing film of Production Example 2 was used instead of the dye-containing polarizing film of Production Example 1, and that the non-polarizing portion was formed by alkali treatment instead of laser light irradiation. Using this laminate as a test sample, tests similar to those in Example 1 were carried out. The results are shown in Table 1. The single transmittance of the formed non-polarizing portion was 90%. The alkali treatment was carried out as follows. An adhesive-attached ester resin film with through-holes formed at predetermined positions was attached to the polarizing film surface of the laminate obtained in Production Example 2. The obtained laminate was immersed in a 1 mol / L (1N) aqueous sodium hydroxide solution for 180 seconds. In this way, the polarizing film was bleached at positions corresponding to the through-holes in the ester resin film, thereby forming non-polarizing portions. After the alkali treatment, the ester resin film was peeled off and removed.

[0085] Comparative Example 3 A laminate having a configuration 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 dye-containing polarizing film of Production Example 1, and that the non-polarizing portion was formed by alkali treatment instead of laser light irradiation. Using this laminate as a test sample, tests similar to those in Example 1 were carried out. The results are shown in Table 1. The alkali treatment was carried out in the same manner as in Comparative Example 2.

[0086] Comparative Example 4 A laminate having a structure of iodine-containing polarizing film / retardation film / adhesive / glass plate was obtained in the same manner as in Comparative Example 2, except that an acid treatment was further performed after the alkali treatment. The laminate was used as a test sample and subjected to the same tests as in Example 1. The results are shown in Table 1. The acid treatment was performed by further immersing the alkali-treated laminate in 1 mol / L (1N) hydrochloric acid for 60 seconds. After the acid treatment, the ester-based resin film was peeled off and removed. The single transmittance of the formed non-polarizing portion was 90%.

[0087] Comparative Example 5 A laminate having a structure of protective layer / iodine-containing polarizing film / retardation film / adhesive / glass plate was obtained in the same manner as in Comparative Example 3, except that an acid treatment was further carried out after the alkali treatment. Using this laminate as a test sample, the same tests as in Example 1 were carried out. The results are shown in Table 1. The acid treatment was carried out in the same manner as in Comparative Example 4.

[0088] Comparative Example 6 A laminate having a structure of protective layer / dye-containing polarizing film / retardation film / adhesive / 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 light irradiation. Using this laminate as a test sample, tests were carried out in the same manner as in Example 1. The results are shown in Table 1. The alkali treatment was carried out in the same manner as in Comparative Example 2, and the acid treatment was carried out in the same manner as in Comparative Example 4.

[0089] [Table 1]

[0090] [evaluation] As is clear from Table 1, according to the examples of the present invention, a polarizing film made of a resin film containing a dichroic organic dye is irradiated with laser light to decolorize it, and non-polarizing portions are formed in the polarizing film, thereby achieving a polarizing film that has excellent shape retention properties for the non-polarized portions and suppresses discoloration of the non-polarized portions.As is clear from Comparative Example 1, when non-polarizing portions are formed by irradiating a polarizing film containing iodine with laser light, the shape of the non-polarized portions is maintained to an acceptable extent, but discoloration of the non-polarized portions is significant.As is clear from Comparative Examples 2 to 5, when non-polarizing portions are formed by alkali treatment, discoloration over time can be suppressed, but shape retention properties are insufficient. [Industrial Applicability]

[0091] The polarizing film, polarizing plate and optical laminate according to the embodiments of the present invention can be suitably used in image display devices (typically, liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0092] 10 Polarizing plate 11 Polarizing film 12 Protective layer 20 Phase difference film 100 Optical laminate

Claims

1. A polarizing film made of a resin film containing a dichroic organic dye and having a non-polarizing portion, when the polarizing film is subjected to a moist heat test in which the polarizing film is left standing in an environment of 65°C and 90% RH for 24 hours, the rate of change in the outer periphery of the non-polarizing portion before and after the moist heat test is 3.0% or less; Polarizing film.

2. A polarizing film made of a resin film containing a dichroic organic dye and having a non-polarizing portion, when the polarizing film is subjected to a moist heat test in which the polarizing film is left standing in 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 moist heat test is 5.0% or less; Polarizing film.

3. the resin film contains a polyvinyl alcohol-based resin, 3. The polarizing film according to claim 1, wherein 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, and a mixture thereof: 【Chemical 1】 (In formula (1), X and Z each represent an atomic group shown in (2) to (13) below; Y represents an atomic group shown in (14) to (29) below; and m represents an integer of 0 to 6.) 【Chemistry 2】 (In formulas (2) to (13), A is H, OH, OR １ , S.O. ３ H, N.H. ２ , N.R. ２ , NO ２ , COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms which may have a linear, branched, or cyclic structure, a double bond, or a triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms which may have a linear, branched, or cyclic structure, a double bond, or a triple bond; n represents an integer of 0 to 5; o represents an integer of 0 to 4; p represents an integer of 0 to 3; q represents an integer of 0 to 2; and r represents 0 or 1. 【Chemistry 3】 (In formulas (14) to (29), B is H, OH, OR １ , S.O. ３ H, N.H. ２ , N.R. ２ , NO ２ , COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms which may have 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).

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

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

6. 3. The polarizing film according to claim 1, wherein, when the polarizing film is subjected to a moist heat test in which the polarizing film is left standing in an environment of 65°C and 90% RH for 24 hours, the absolute value of the change in single-unit transmittance of the non-polarizing part before and after the moist heat test is 3.0 or less.

7. The polarizing film according to claim 1 or 2, wherein the non-polarizing portion is a laser-bleached portion.

8. The polarizing film according to claim 1 or 2; a protective layer provided on at least one side of the polarizing film; A polarizing plate comprising:

9. The polarizing plate according to claim 8 , further comprising a protective layer provided on both sides of the polarizing film.

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

Images