Polarizing films, polarizing plates, and optical laminates

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 Art

[0002] In recent years, image display devices represented by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. Typically, a polarizing film containing iodine is used for such image display devices. Further, in order to cope with diversification and high functionality of the shape of the image display device, a polarizing film having partially polarizing performance is required. As a method for manufacturing such a polarizing film, a technique is known in which a part of the polarizing film is irradiated with laser light containing light having a wavelength of 1500 nm or less to decolorize and form a non-polarizing portion (for example, Patent Document 1). Alternatively, a technique is known in which a part of the polarizing film is brought into contact with a basic substance to decolorize and form a non-polarizing portion (for example, Patent Document 2). However, the non-polarizing portion of the polarizing film manufactured by the method described in Patent Document 1 can maintain its shape, but the non-polarizing portion (decolorized portion) may be recolored over time. The non-polarizing portion of the polarizing film manufactured by the method described in Patent Document 2 can suppress recoloring over time, but the shape maintaining performance is insufficient.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a polarizing film having a non-polarizing portion, having excellent shape retention performance of the non-polarizing portion, and having suppressed color recoloring of the non-polarizing portion. [Means for solving the problem]

[0005] [1] A polarizing film according to one embodiment of the present invention is composed of a resin film containing a dichroic organic dye and has a non-polarizing portion, and when the polarizing film 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 rate of change of the outer circumference of the non-polarizing portion before and after the moist heat test is 3.0% or less. [2] A polarizing film according to another embodiment of the present invention is composed of a resin film containing a dichroic organic dye and has a non-polarizing portion, and when the polarizing film 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 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 comprises a polyvinyl alcohol-based resin, and 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 equation (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; and m represents an integer from 0 to 6.) [ka] (In equations (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, branched, cyclic structure, double bond, or triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms that may contain a linear, branched, cyclic structure, double bond, or 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) [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 that may include branched structures, cyclic structures, double bonds, or triple bonds; R, n, o, p, q, and r are the same as in formulas (2) to (13) above). [4] In any of the above [1] to [3], the polarizing film has a content of dichroic organic dye in the non-polarizing portion which is 3.0% by mass or less, when the content of dichroic organic dye in the polarizing film excluding the non-polarizing portion is taken as 100% by mass. [5] In any of the above [1] to [4], the haze value of the non-polarized portion is 5.0% or less. [6] In any of the above [1] to [5], when the polarizing film 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 in the transmittance of the non-polarized portion before and after the moist heat test is 3.0 or less. [7] In any of the above [1] to [6], the non-polarized portion is a laser decolorized portion. [8]According to another aspect of the present invention, a polarizing plate is provided, comprising a polarizing film as described in any of [1] to [7] above, and a protective layer provided on at least one of the polarizing films. [9] In the above [8], the polarizing plate is provided with protective layers on both sides of the polarizing film.

[10] According to yet another aspect of the present invention, an optical laminate is provided, comprising a polarizing film as described in [1] to [7] above, a protective layer provided on one side of the polarizing film, and a phase difference film provided on the other side of the polarizing film, wherein the in-plane phase difference Re(550) of the phase difference film is 100 nm to 180 nm, and the angle between the absorption axis direction of the polarizing film and the slow axis direction of the phase difference film is 40° to 50°. [Effects of the Invention]

[0006] According to embodiments of the present invention, a polarizing film can be realized that has a non-polarizing portion, exhibits excellent shape retention performance of the non-polarizing portion, and suppresses the recoloring of the non-polarizing portion. [Brief explanation of the drawing]

[0007] [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. [Figure 2] Figure 1 is a schematic cross-sectional view of an optical laminate including a polarizing plate. [Modes for carrying out the invention]

[0008] The following describes typical embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, the drawings are schematic representations for ease of understanding and do not represent the actual lengths, widths, thicknesses, or their proportions in each layer.

[0009] (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase 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 obtained by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, "45°" means ±45°. (4) Substantially parallel or orthogonal The expressions "substantially orthogonal" and "substantially perpendicular" include cases where the angle formed by two directions is 90° ± 10°, preferably 90° ± 7°, and more preferably 90° ± 5°. The expressions "substantially parallel" and "substantially parallel to" include cases where the angle formed by two directions is 0° ± 10°, preferably 0° ± 7°, and more preferably 0° ± 5°. Furthermore, when simply referring to "orthogonal" or "parallel" in this specification, it shall include a state that is substantially orthogonal or substantially parallel.

[0010] A. Overview of the 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 in the illustrated example is composed of a resin film containing a dichroic organic dye. The polarizing film 11 has an unpolarized portion 15. In the embodiment of the present invention, the unpolarized portion 15 is excellent in shape maintenance performance after a damp heat test. In one embodiment, when the polarizing film is subjected to a damp heat test of standing still in an environment of 65° C. and 90% RH for 24 hours, the change rate of the outer periphery of the unpolarized portion before and after the damp heat test is 3.0% or less. The change rate of the outer periphery is preferably 2.5% or less, more preferably 1.5% or less, still more preferably 1.0% or less, and particularly preferably 0.7% or less. The lower limit of the change rate of the outer periphery is ideally zero and can be, for example, 0.1%. In another embodiment, when the polarizing film is subjected to a damp heat test of standing still in an environment of 65° C. and 90% RH for 24 hours, the change rate of the area of the unpolarized portion before and after the damp heat test is 5.0% or less. The change rate of the area is preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, and particularly preferably 0.5% or less. The lower limit of the change rate of the area is ideally zero and can be, for example, 0.1%. According to the embodiment of the present invention, thus, the shape of the unpolarized portion is well maintained from both the viewpoints of the outer periphery and the area, so that a highly commercially valuable polarizing film can be realized. The change rates of the outer periphery and the area are respectively obtained by the following formulas. Outer periphery change rate (%) = |(outer periphery length after test) - (outer periphery length before test)| / (outer periphery length before test) × 100 Area change rate (%) = |(area after test) - (area before test)| / (area before test) × 100 The outer periphery length (mm) and the area (mm 2 ) are respectively obtained by imaging the unpolarized portion with an imaging device and processing the obtained image.

[0011] The single-layer transmittance Ts of the polarizing film 11 (excluding the non-polarizing portion 15) for light with wavelengths 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-layer transmittance Ts may be, for example, 45.0% or less, or for example, 44.0% or less. The degree of polarization 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. On the other hand, the degree of polarization P may be, for example, 99.95% or less, or for example, 99.90% or less. The single-unit transmittance Ts of the unpolarized portion 15 for light with wavelengths of 380 nm to 780 nm is, for example, 70.0% or more, preferably 85.0% or more, and more preferably 90.0% or more. The degree of polarization P of the unpolarized portion 15 is, 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-unit transmittance Ts can be calculated, for example, as the Y value after measuring with a 2-degree field of view (C light source) according to JIS Z8701 and correcting for luminous efficiency.

[0012] When the 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 in the transmittance of the non-polarized portion 15 before and after the moist heat test, ΔY, 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 especially preferably 0.9 or less. The lower limit of the absolute value of ΔY is ideally zero, and can be, for example, 0.1, or 0.2. According to the embodiment of the present invention, as described above, excellent shape retention performance is achieved for the non-polarized portion, and the recoloring of the non-polarized portion can be suppressed in this way. As a result, a polarizing film with very high commercial value and in which the function of the non-polarized portion can be maintained over a long period of time can be realized.

[0013] When the 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 in the single-phase hue L value of the Lab color system of the non-polarized portion 15 before and after the moist heat test, ΔL, 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 may be, for example, 0.0. The absolute value of the change in the single-phase hue a value of the Lab color system of the non-polarized portion 15 before and after the above moist heat test, Δa, 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 may be, for example, 0.0. The single-phase hue L and single-phase hue a values ​​of the Lab color system are measured, for example, by a spectrophotometer (typically, the "LPF-200" model, manufactured by Otsuka Electronics Co., Ltd.). According to the embodiment of the present invention, the recolorization of the non-polarized portion can be suppressed as described above. As a result, the absolute values ​​of ΔL and Δa can also be such small values.

[0014] The absorbance of the unpolarized 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 at wavelengths of 470 nm, 560 nm, and 700 nm, respectively. On the other hand, the absorbance of the unpolarized portion 15 for the above-mentioned light is, for example, 0.001 or more, preferably 0.01 or more. If the absorbance of the unpolarized portion is within this range, the light transmittance of the unpolarized portion is good, and the function of the unpolarized portion can be properly exhibited. The absorbance of the unpolarized portion is measured, for example, in accordance with JIS K 0115.

[0015] The haze value of the unpolarized 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 unpolarized portion 15 is preferably as small as possible, for example, it may be 0.0%. If the haze value of the unpolarized portion is within this range, the light transmittance of the unpolarized portion is good, and the function of the unpolarized portion can be properly exhibited.

[0016] The non-polarized portion 15 is typically a laser-decolorized portion. More specifically, the non-polarized portion 15 is a decolorized portion that has been decolorized by irradiation with laser light from a solid-state pulsed laser. With such a configuration, in combination with the fact that the polarizing film is composed 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-polarized portion and suppresses the recoloration of the non-polarized portion. As a result, it is possible to realize a polarizing film that has very high commercial value and in which the function of the non-polarized portion can be maintained over a long period of time.

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

[0018] The content of the dichroic organic dye in the non-polarized 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, when the content of the dichroic organic dye in the polarizing film 11 excluding the non-polarized portion 15 is taken as 100% by mass. The smaller the content of the dichroic organic dye in the non-polarized portion 15, the better, and it may be, for example, 0.0% by mass. If the content of the dichroic organic dye in the non-polarized portion is within this range, the light transmittance of the non-polarized portion can be improved and the recoloring of the non-polarized portion 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, even more 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 following describes the resin film and the dichroic organic dye in detail.

[0021] B. Resin film Any resin applicable to polarizing films 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 PVA-based resin). Examples of PVA-based resins include polyvinyl alcohol, acetal-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. PVA-based resins may be used alone, or two or more PVA-based resins with different types of modification, modification rates, degrees of polymerization, and degrees of saponification may be used in combination.

[0022] PVA-based resins typically contain polyvinyl alcohol. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The polyvinyl alcohol content in PVA-based resins is, for example, 80% to 100% by mass, 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 degree of saponification of PVA resins is typically 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 degree of saponification is measured, for example, in accordance with JIS K 6726-1994. By using PVA resins with such a degree of saponification, a thin polarizing film with excellent durability can be realized.

[0025] The average degree of polymerization of PVA resins can be appropriately selected depending on the purpose. For example, the average degree of polymerization may be 1000 or higher, preferably 1500 or higher, more preferably 2000 or higher, and even more preferably 3000 or higher. On the other hand, the average degree of polymerization may be 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 K 6726-1994.

[0026] C. Dichroic organic dye Any suitable dye can be used as the dichroic organic dye. Examples of dichroic organic dyes include 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 made from these.

[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.), dipyromethene dyes, quinone dyes (benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, anthrapyridone dyes, etc.), carbonium dyes (diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, acridine dyes, etc.), and quinoneimine dyes (oxazine dyes, thiazine dyes). Examples include dichroic dyes, 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 their metal complex dyes. Dichroic organic dyes can be used alone or in combination.

[0028] Among dichroic organic dyes, direct dyes are preferred, and azo dyes are more preferred. When the dichroic organic dye is an azo dye, the color recoloring in the non-polarized areas can be suppressed more stably. 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 equation (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; and m represents an integer from 0 to 6.) In equation (1) above, X and Z may be the same or different from each other. Also, when m is between 2 and 6, the multiple Y values ​​may be the same or different from each other.

[0029] [ka] (In equations (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 include a linear, branched, cyclic structure, double bond, or triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms that may include a linear, branched, cyclic structure, double bond, or 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.)

[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 include branched structures, cyclic structures, double bonds, or triple bonds; R, n, o, p, q, and r are the same as in formulas (2) to (13) above).

[0031] Among the atomic groups represented by formulas (2) to (13) above (i.e., X and Z in formula (1) above), preferably, the atomic groups represented by formulas (2), (7), (8), and (13) above are mentioned. Among the atomic groups represented by formulas (14) to (29) above (i.e., Y in formula (1) above), preferably, the atomic groups represented by formulas (14), (22), (24), (28), and (29) above are mentioned. In the atomic groups represented by the above formulas (2) to (13), if there are multiple A atoms, the multiple A atoms may be identical to each other or may be different from each other. In the atomic groups represented by the above formulas (14) to (29), if there are multiple B atoms, the multiple B atoms may be the same as or different from each other. In the atomic groups represented by the above formulas (2) to (29), if there are multiple R atoms, the multiple R atoms may be the same as or different from each other.

[0032] Examples of salts of azo dyes include ammonium salts, alkaline earth metal salts, transition metal salts, and oligometal salts. Examples of chelates for azo dyes include chelates of metal elements with hydroxyl-containing azo dyes, chelates of alkoxy-containing azo dyes, and chelates of carboxyl-containing azo dyes.

[0033] Among azo dyes, preferred examples include Direct Red 80, Direct Red 81, Direct Blue 2, Direct Yellow 8, and Direct Violet 9.

[0034] D. Polarizing plate As shown in Figure 1, the polarizing films described in items A to C above can be suitably applied to polarizing plates. A polarizing plate equipped with the above polarizing film has excellent shape retention performance of the non-polarized portion and suppresses recoloration of the non-polarized portion, similar to the polarizing film itself. The polarizing plate 10 in the illustrated 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 illustrated example, the protective layer 12 is provided on only one side of the polarizing film 11. Although not shown, the protective layer may be provided on both sides of the polarizing film 11. By providing the protective layer on both sides of the polarizing film, the shape retention performance of the non-polarized portion can be further improved. The protective layer may be attached to the polarizing film via an adhesive layer or via a bonding agent layer.

[0035] The protective layer is formed from any suitable film that can be used as a protective layer for the polarizing film. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), polyester resins such as polyethylene terephthalate (PET), polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, cycloolefin (COP) resins, (meth)acrylic resins, and acetate resins. Thermosetting resins or UV-curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and silicone resins can also be used. In addition, glassy polymers such as siloxane polymers can also be used. Polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. Note that "(meth)acrylic" refers to acrylic and / or methacrylic resins. Among the materials for the protective layer, materials without multiple aromatic rings are preferred, materials without aromatic rings as the main component are preferred, and transparent materials without PET are even more preferred. When the protective layer is made of a material without aromatic rings, even if the decolorization process described later is performed on the polarizing plate, damage to the protective layer by laser light can be suppressed, and scorching of the protective layer can be suppressed.

[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. On the other hand, 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 side opposite to the polarizing film). Examples of surface treatment layers include a hard coat layer, an anti-reflective layer, an anti-sticking layer, and an anti-glare layer. The thickness of the surface treatment layer can be any appropriate thickness depending on the purpose and type of 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 films described in items A to C above and the polarizing plates described in item D above can be applied to optical laminates. Optical laminates equipped with the above polarizing films exhibit excellent shape retention performance in the non-polarized areas, similar to polarizing films, and suppress recoloration of the non-polarized areas. Figure 2 is a schematic cross-sectional view of the optical laminate including the polarizing plate shown in Figure 1. The illustrated optical laminate 100 comprises the polarizing plate 10; a phase difference film 20 attached to the polarizing plate 10 via an adhesive layer 30; and an adhesive layer 40 located on the opposite side of the polarizing plate 10 from the phase difference film 20.

[0039] 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 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, 100 nm to 180 nm, preferably 135 nm to 155 nm. The phase difference film 20 may consist of one layer or two or more layers. The phase difference film is typically composed of a stretched film of a polyester carbonate resin film. With such a configuration, the phase difference 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 opposite to the phase difference film of the polarizing film, as in the illustrated example, the shape retention performance of the non-polarized portion can be improved, similar to when protective layers are provided on both sides of the polarizing film.

[0040] The angle between the absorption axis direction of the polarizing film 11 and the slow phase axis direction of the phase difference 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 polarizer.

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

[0042] F. Method for manufacturing polarizing films Next, one embodiment of a method for manufacturing a polarizing film will be described. 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 dye described in item C above; a stretching step of stretching the resin film; and a decolorization step of irradiating a portion of the dyed and stretched resin film with laser light using a solid pulsed laser to decolorize it and form a non-polarizing portion. The above method for manufacturing a polarizing film may further include a swelling step, an insolubilization step and / or a washing step. In the swelling step, typically the resin film before the dyeing step is immersed in a swelling bath (swelling solution). In the washing step, typically the resin film after the stretching step and before the decolorization step is immersed in a washing bath. The following section will detail the case where the resin film is the PVA-based resin film described above.

[0043] F-1. PVA-based resin film The PVA resin film before each of the above processes is carried out is used as the raw film. The raw material film may be a single layer resin film, or it may be laminated on a thermoplastic resin substrate.

[0044] Specific examples of single-layer resin films include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films, as well as polyene-based oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. When the raw material film is a single-layer resin film, its thickness is, for example, 20 μm to 65 μm, preferably 30 μm to 60 μm.

[0045] When the base film is laminated onto a thermoplastic resin substrate, the base film may be a PVA-based resin film supported by the resin substrate, or it may be a PVA-based resin layer applied to the resin substrate.

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

[0047] The constituent materials of the resin substrate can be any suitable material. Typical constituent materials of the resin substrate include amorphous (non-crystallized) polyethylene terephthalate resins, and preferably amorphous (less crystallized) polyethylene terephthalate resins. 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, amorphous isophthal copolymer polyethylene terephthalate film resin substrates are preferred. The thickness of the resin substrate before stretching is, for example, 20 μm to 300 μm, preferably 50 μm to 200 μm. The surface of the resin substrate may be subjected to any appropriate surface treatment (e.g., corona treatment), and an easy-adhesion layer may be formed thereon. This can improve the adhesion between the resin substrate and the PVA-based resin layer.

[0048] The coating solution is typically a solution obtained by dissolving the PVA-based resin mentioned above in a solvent. The PVA-based resin content in the coating solution is, for example, 3 to 20 parts by mass per 100 parts by mass of solvent. With such a resin concentration, a uniform coating film that adheres closely 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 can be used alone or in combination. Among the solvents, water is preferred.

[0050] The coating solution may contain iodide or sodium chloride (sometimes collectively referred to as halides). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The amount of halide added to 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 PVA resin. By incorporating halides into the coating solution, halides can be introduced into the resulting polarizing film. Introducing halides into the polarizing film can improve the orientation of PVA molecules in the polarizing film, thereby enabling the realization of a polarizing film with excellent optical properties (typically, a combination of high polarization degree and high single-component transmittance).

[0051] Additives may be added to the coating solution. 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 solution 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 an auxiliary stretching process in advance and air-stretched in the longitudinal direction. The stretching temperature in the auxiliary stretching process is typically above the glass transition temperature (Tg) of the PVA resin, for example, 95°C or higher, preferably 120°C or higher. Alternatively, the stretching temperature in the auxiliary stretching process is typically 150°C or lower. The stretching ratio of the laminate in the auxiliary stretching process 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 process is typically 4 times. The aerial stretching method in the auxiliary stretching process may be fixed-end stretching (for example, stretching using a tenter stretcher) or free-end stretching (for example, uniaxial stretching by passing the laminate between rolls with different peripheral speeds).

[0054] F-2. Swelling process The raw film described above (either the raw film alone or the raw film included in a laminate) is subjected to the swelling process described above before the dyeing process, if necessary. In the swelling process, the raw film is typically immersed in a swelling solution (swelling bath). The swelling solution may be pure water or an aqueous boric acid solution. When the swelling solution is an aqueous boric acid solution (i.e., an insolubilization solution), the swelling process also serves as an insolubilization process. The boric acid content in the insolubilization solution 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°C to 60°C, preferably 20°C to 50°C. The immersion time in the swelling process is, for example, 10 seconds to 200 seconds, preferably 20 seconds to 60 seconds.

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

[0056] In one embodiment, the dyeing process involves immersing the PVA resin film in the dyeing bath. The temperature of the dyeing bath is, for example, 10°C to 80°C, preferably 20°C to 60°C. The immersion time (dyeing time) in the dyeing process is, for example, 5 seconds to 300 seconds, preferably 10 seconds to 60 seconds. Furthermore, the method of adsorption of the dye in the dyeing process is not limited to the immersion method described above. For example, the dyeing solution may be coated onto the PVA resin film, or the dyeing solution may be sprayed onto the PVA resin film.

[0057] F-4. Stretching process In one embodiment, the stretching step involves stretching the PVA resin film after the dyeing step in the longitudinal direction in an aqueous boric acid solution, which serves as a stretching bath. Stretching the PVA resin film in an aqueous boric acid solution can suppress the dissolution of the PVA resin film into the aqueous boric acid solution. The stretching ratio in the stretching process varies depending on whether or not an auxiliary stretching process is performed on the raw film. If an auxiliary stretching process is not performed on the raw film (i.e., the raw film is a single layer resin film or a resin film supported on a resin substrate), the stretching ratio in the stretching process is, for example, 4.5 to 7 times, preferably 5.0 to 6.5 times. When an auxiliary stretching process is performed on the raw film (i.e., when the raw film is a PVA-based resin layer coated and formed on a resin substrate), the stretching ratio in the stretching process 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 process and the stretching ratio in the stretching process is, for example, 4.5 to 7.0 times, preferably 5.0 to 6.5 times. By stretching the film at the stretching ratio described above, it is possible to impart extremely excellent polarization properties to the polarizing film.

[0058] The boric acid content in the stretching solution (boric acid aqueous solution) is, for example, 0.5 to 5.0 parts by mass, preferably 0.7 to 3.0 parts by mass, per 100 parts by mass of water. The temperature of the stretching bath is, for example, 40°C to 85°C, preferably 50°C to 65°C. If the temperature of the stretching bath is below the above upper limit, the dissolution of the PVA resin in the stretching bath can be stably suppressed, even if the concentration of boric acid in the stretching bath is below the above upper limit. The immersion time in the stretching process is, for example, 15 seconds to 300 seconds.

[0059] F-5. Washing process In the washing process, typically the PVA resin film after the stretching process is immersed in a washing bath. The washing bath is typically water. The temperature of the washing bath is, for example, 0°C to 40°C, preferably 10°C to 30°C. The immersion time in the washing process is, for example, 5 seconds to 200 seconds, preferably 10 seconds to 60 seconds.

[0060] F-6. Drying shrinkage process The PVA resin film after the washing process is preferably subjected to a drying shrinkage process before the decolorization process. In the drying shrinkage process, the PVA resin film is typically heated while being conveyed in the longitudinal direction. The drying shrinkage process is carried out by a heating and drying section. The heating and drying section may be a zone heating system in which the entire interior of the heating and drying section is heated, or a heated roll drying system in which the conveying 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°C to 120°C, preferably 80°C to 100°C. The surface temperature of the heating roll is, for example, 60°C to 100°C, preferably 70°C to 80°C. By drying using heated rollers, the heat curl of the PVA resin film (laminated) can be efficiently suppressed, enabling the efficient production of polarizing films with excellent appearance. Furthermore, during the drying shrinkage process, the PVA resin film shrinks in the width direction perpendicular to the length direction. The shrinkage rate in the width direction of the PVA resin film during the drying shrinkage 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 PVA and PVA / each dichroic organic dye can be improved, and the polarization characteristics of the polarizing film (excluding the non-polarized 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 occurrence of appearance defects such as wrinkles in the polarizing film can be suppressed.

[0061] As described above, a polarizing film 11 can be produced before the formation of the non-polarizing portion 15.

[0062] F-7. Decolorization (formation of non-polarized part) process In the decolorization process, laser light from a solid-state pulsed laser is irradiated onto any appropriate portion of the polarizing film 11 according to its purpose and application. In the decolorization process, the target of laser light irradiation may be only the polarizing film 11, a polarizing plate 10 equipped with the polarizing film 11, or an optical laminate 100 equipped with the polarizing plate 10. That is, the polarizing film may be laminated with the above layers and / or films (e.g., a protective layer, a phase difference film, an adhesive layer) after forming a non-polarized portion on the polarizing film, or the non-polarized portion may be formed on the polarizing film after laminating the above layers and / or films. When the polarizing plate 10 or optical laminate 100 is subjected to a decolorization process, 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 beam is moved at a predetermined processing speed to irradiate the entire area of ​​the non-polarized portion of the polarizing film 11. In this way, by irradiating a polarizing film composed of a resin film containing a dichroic organic dye with a predetermined laser beam, a non-polarized portion can be formed that has excellent light transmittance, excellent shape retention, and suppressed color recoloring. Furthermore, by adjusting the laser beam irradiation conditions, the color tone of the formed non-polarized portion can be appropriately adjusted.

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

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

[0065] The frequency of the laser light is preferably 0.1kHz to 200kHz, more preferably 0.2kHz to 100kHz, even more preferably 0.3kHz to 80kHz, and particularly preferably 0.4kHz to 70kHz. 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, even 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 are within this range, the haze in the unpolarized region can be reduced more stably.

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

[0067] The processing speed of the laser beam is, for example, 1.0 × 10⁻⁶. -2 The speed range is from cm / s to 100.0 cm / s, preferably 5.0 × 10 -2 The range is from cm / s to 50.0 cm / s, and more preferably from 0.1 cm / s to 25.0 cm / s. The ratio of the laser light frequency to the laser light processing speed (frequency (kHz) / processing speed (cm / s)) is, for example, 0.001 to 200, and preferably 0.1 to 5.0.

[0068] Preferably, the laser light contains polarization that is substantially parallel to the absorption axis of the polarizing film 11. When the laser light contains such polarization, the desired areas of the polarizing film can be decolorized more smoothly, and unpolarized areas can be efficiently formed.

[0069] When a decolorization process is performed on a polarizing film composed of a resin film containing a dichroic organic dye under these conditions, it is possible to form a non-polarizing portion that has excellent light transmittance, excellent shape retention performance, and suppressed recoloration, while also suppressing damage to the polarizing film itself.

[0070] As described above, a polarizing film having a non-polarizing portion can be produced. Furthermore, if a polarizing plate is used in the decolorization process, a polarizing plate having a non-polarizing portion can be produced, and if an optical laminate is used in the decolorization process, an optical laminate having a non-polarizing portion can be produced. [Examples]

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

[0072] (1) Rate of change of the unpolarized portion The non-polarized portion of the polarizing films obtained in the examples and comparative examples was imaged using an imaging device (EPSON, product name "GT-S650") (resolution 300 dpi). The obtained images were binarized, and the outer circumference length (mm) and area (mm²) before testing were determined. 2 The ) was determined. 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 for 12 or 24 hours in an environment of 65°C and 90%RH, and then the outer circumference length (mm) and area (mm) after testing were determined in the same manner as above. 2 The following formulas were used to calculate the rate of change of the perimeter and area. Note that the selection of the code for the above process is arbitrary. For example, the above process can be executed with various code including C++, Python, machine language, etc. Percentage change in circumference (%) = |(Circumference length after test) - (Circumference length before test)| / (Circumference length before test) × 100 Area change rate (%) = |(Area after test) - (Area before test)| / (Area before test) × 100 Based on the rate of change obtained as described above, the shape retention performance was evaluated according to the following criteria. <Outer perimeter> 5 (Excellent): Change rate is 1% or less 4 (Good): Rate of change is greater than 1% and less than or equal to 3%. 3 (Acceptable): Rate of change is greater than 3% but less than or equal to 5% 2 (Insufficient): Rate of change is greater than 5% but less than or equal to 15% 1 (Defective): Change rate exceeds 15% <Area> 5 (Excellent): Change rate is 0.5% or less 4 (Good): Rate of change greater than 0.5% and less than or equal to 2% 3 (Acceptable): Rate of change is greater than 2% but less than or equal to 5% 2 (Insufficient): Rate of change is greater than 5% but less than or equal to 15% 1 (Defective): Change rate exceeds 15%

[0073] (2) Change in individual transmittance ΔY The transmittance Ts of the unpolarized portion of the polarizing films obtained in the examples and comparative examples was measured using a spectrophotometer (product name: U-4100, Hitachi High-Tech Corporation). The transmittance Ts was measured using a 2-degree field of view (C light source) according to JIS Z8701 and is the Y value after luminous efficiency correction. 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 for 12 or 24 hours in an environment of 65°C and 90%RH, and the transmittance of the unpolarized portion was measured in the same manner as above. The difference between the value after the test and the value before the test was calculated as ΔY.

[0074] (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 The L, a, and b values ​​of the non-polarized portion 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 for 12 or 24 hours in an environment of 65°C and 90%RH, and the L, a, and b values ​​of the non-polarized portion were measured in the same manner as above. The difference obtained by subtracting the pre-test value from the post-test value was calculated as ΔL, Δa, and Δb.

[0075] (4) Percentage of pigment content in the non-polarized portion (amount of residual pigment) The absorbance of the polarizing films (excluding the non-polarized portion) and the non-polarized portion obtained in the examples and comparative examples was measured using a spectrophotometer (product name: U-4100, manufactured by Hitachi High-Tech Corporation). Furthermore, the content ratio of dichroic substances (residual pigment amount) in the non-polarized portion was calculated using the following formula (II). Dye residue amount (mass%) = (absorbance of the non-polarized portion / absorbance of the non-polarized portion) × percentage of dichroic substance in the non-polarized portion of the polarizing film (mass%) ... (II)

[0076] [Manufacturing Example 1: Fabrication of an organic dye-containing polarizing film] As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the laminate was immersed in a staining bath at a liquid temperature of 30°C for 60 seconds (staining treatment). The staining 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 concentration was adjusted so that the transmittance Ts of the resulting polarizing film was at the desired value. Next, the laminate was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the laminate was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizing film with a thickness of approximately 5 μm was formed on a resin substrate, and a laminate having the configuration of resin substrate / dye-containing polarizing film was obtained. The transmittance of the obtained polarizing film alone was 41%.

[0077] [Manufacturing Example 2: Fabrication of Iodine-Containing Polarizing Film] A laminate having a resin substrate / iodine-containing polarizing film (thickness approximately 5 μm) 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 in a weight ratio of 1:7 was used as the staining bath. The concentration of the staining bath (iodine aqueous solution) was adjusted so that the transmittance Ts of the obtained polarizing film was a desired value. The transmittance of the obtained polarizing film was 41%.

[0078] [Manufacturing Example 3: Fabrication of Phase Difference 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 reduced pressure nitrogen, it was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the process to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was directed to a 100°C reflux condenser, and the monomer components contained in the phenol vapor were returned to the reactor. The uncondensed phenol vapor was then directed to a 45°C condenser for recovery. Nitrogen was introduced into the first reactor to restore pressure to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and depressurization in the second reactor were started, and the internal temperature reached 240°C and the pressure 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate resin was extruded into water. The strands were then cut to obtain pellets. The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours. Then, a long resin film was produced using a film-making apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120~130°C), and a winding machine. The obtained long resin film was stretched longitudinally at the free end at 140°C to obtain a phase difference film with a thickness of 40 μm. The refractive index characteristics of the phase difference film showed the relationship nx>ny=nz (positive A plate).

[0079] [Example 1] In Manufacturing Example 1, a green laser beam was irradiated onto a predetermined position of the polarizing film of the laminate from the resin substrate side using a solid-state pulsed laser to form a non-polarized region (approximately circular with a diameter of about 10 mm). The laser beam irradiation conditions were as follows. The transmittance of the formed non-polarized region was 88%, and the dye residue amount was 1.0 mass%. Laser light: Yb laser Oscillator: LIGHT CONVERSION Co., Ltd., product name "PHAROS" Wavelength: 513nm Output: 10W@50kHz Pulse width: 290 fs ~ 15 ps Scanning method: Galvanometer scanner Focal length: 163mm

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

[0081] [Example 2] A non-polarized 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 phase difference film from Manufacturing Example 3 was bonded to the polarizing film side of the resin substrate / dye-containing polarizing film laminate via an adhesive. Furthermore, a glass plate was bonded to the phase difference film via an adhesive, and then the resin substrate was peeled off to obtain a laminate having the configuration of dye-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 performed. The results are shown in Table 1.

[0082] [Example 3] A laminate having the configuration of a resin substrate / dye-containing polarizing film / phase difference film was obtained in the same manner as in Example 2. The resin substrate was peeled off this laminate, and a (meth)acrylic film (manufactured by Toyo Kohan Co., Ltd., product name "RV20", thickness 20 μm) as a protective layer was bonded to the peeled surface via an ultraviolet-curing adhesive. Furthermore, a glass plate was bonded to the phase difference film of the laminate via an adhesive, obtaining a laminate having the configuration of a protective layer / dye-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 performed. The results are shown in Table 1.

[0083] [Comparative Example 1] A laminate having the configuration of a protective layer / iodine-containing polarizing film / phase difference 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. The same tests as in Example 1 were performed on this laminate as a test sample. The results are shown in Table 1. The transmittance of the formed non-polarized portion was 70%.

[0084] [Comparative Example 2] A laminate having the configuration of iodine-containing polarizing film / phase difference 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 the non-polarized portion was formed by alkaline treatment instead of laser irradiation. The same test as in Example 1 was performed on this laminate as a test sample. The results are shown in Table 1. The transmittance of the formed non-polarized portion alone was 90%. The alkali treatment was carried out as follows: An adhesive ester resin film with through-holes formed at predetermined positions was bonded to the polarizing film surface of the laminate obtained in Production Example 2. The resulting laminate was immersed in a 1 mol / L (1N) sodium hydroxide aqueous solution for 180 seconds. In this way, non-polarized areas were formed in the polarizing film by decolorizing the positions corresponding to the through-holes of the ester resin film. After the alkali treatment, the ester resin film was peeled off.

[0085] [Comparative Example 3] A laminate having the configuration of a protective layer / iodine-containing polarizing film / phase difference 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 the non-polarized portion was formed by alkaline treatment instead of laser irradiation. This laminate was used as a test sample and tested in the same manner as in Example 1. The results are shown in Table 1. The alkaline treatment was performed in the same manner as in Comparative Example 2.

[0086] [Comparative Example 4] A laminate comprising an iodine-containing polarizing film, a phase difference film, an adhesive, and a glass plate was obtained in the same manner as in Comparative Example 2, except that an acid treatment was performed after the alkali treatment. 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. The acid treatment was performed by immersing the laminate that had been subjected to alkali treatment in 1 mol / L (1N) hydrochloric acid for 60 seconds. After the acid treatment, the ester-based resin film was peeled off. The transmittance of the formed non-polarized portion was 90%.

[0087] [Comparative Example 5] A laminate comprising a protective layer, an iodine-containing polarizing film, a phase difference 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 tests as in Example 1 were conducted. The results are shown in Table 1. The acid treatment was performed in the same manner as in Comparative Example 4.

[0088] [Comparative Example 6] A laminate having the configuration of a protective layer / dye-containing polarizing film / phase difference film / adhesive / glass plate was obtained in the same manner as in Example 3, except that the non-polarized portion was formed by alkaline treatment and acid treatment instead of laser irradiation. This laminate was used as a test sample and tested in the same manner as in Example 1. The results are shown in Table 1. The alkaline 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.

[0089] [Table 1]

[0090] [evaluation] As is clear from Table 1, according to the embodiments of the present invention, by irradiating a polarizing film composed of a resin film containing a dichroic organic dye with laser light to decolorize it and forming a non-polarized portion in the polarizing film, it is possible to realize a polarizing film that has excellent shape retention performance of the non-polarized portion and suppresses the recoloration of the non-polarized portion. As is clear from Comparative Example 1, when a non-polarized portion is formed by irradiating a polarizing film containing iodine with laser light, the shape of the non-polarized portion is maintained to an acceptable degree, but the recoloration of the non-polarized portion is significant. As is clear from Comparative Examples 2 to 5, when a non-polarized portion is formed by alkali treatment, the recoloration over time can be suppressed, but the shape retention performance is insufficient. [Industrial applicability]

[0091] The polarizing film, polarizing plate, and optical laminate according to 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 plates 11 Polarizing film 12 Protective layer 20 Phase difference film 100 Optical laminate

Claims

1. A polarizing film composed of a resin film containing a dichroic organic dye, having a non-polarizing portion, The resin film contains a polyvinyl alcohol-based resin, The dichroic organic dye comprises one selected from azo dyes, salts of azo dyes, chelates of azo dyes, or mixtures thereof. The non-polarized portion is a laser decolorization portion, When the polarizing film 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 rate of change at the outer circumference of the non-polarized portion before and after the moist heat test is 3.0% or less. Polarizing film.

2. A polarizing film composed of a resin film containing a dichroic organic dye, having a non-polarizing portion, The resin film contains a polyvinyl alcohol-based resin, The dichroic organic dye comprises one selected from azo dyes, salts of azo dyes, chelates of azo dyes, or mixtures thereof. The non-polarized portion is a laser decolorization portion, When the polarizing film is subjected to a moist heat test in which it is left standing for 24 hours at 65°C and 90% RH, the rate of change in the area of ​​the non-polarized portion before and after the moist heat test is 5.0% or less. Polarizing film.

3. The aforementioned resin film contains a polyvinyl alcohol-based resin, The polarizing film according to claim 1 or 2, wherein the dichroic organic dye comprises a compound represented by the following formula (1): 【Chemistry 1】 (In equation (1), X and Z each represent one of the atomic groups shown in (2) to (13) below; Y represents one of the atomic groups shown in (14) to (29) below; and m represents an integer from 0 to 6.) 【Chemistry 2】 (In equations (2) to (13), A is H, OH, OR １ SO ３ H, NH ２ , NR ２ NO ２ , COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms that may contain a linear, branched, cyclic, double, or triple bond; R represents a hydrocarbon group having 1 to 12 carbon atoms that may contain a linear, branched, cyclic, double, or 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. 【Transformation 3】 (In formulas (14) to (29), B is H, OH, OR １ , SO ３ H, NH ２ , NR ２ , NO ２ , COOH, COOR, NHCOR, or a hydrocarbon group having 1 to 12 carbon atoms which 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 in the above formulas (2) to (13)).

4. The polarizing film according to claim 1 or 2, 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. The polarizing film according to claim 1 or 2, wherein the haze value of the non-polarized 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 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 in the transmittance of the non-polarized portion before and after the moist heat test is 3.0 or less.

7. A polarizing film according to claim 1 or 2, A protective layer provided on at least one of the polarizing films, A polarizing plate equipped with a polarizing plate.

8. The polarizing plate according to claim 7, wherein protective layers are provided on both sides of the polarizing film.

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

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