WO2022191033A1

WO2022191033A1 - Polarizing plate

Info

Publication number: WO2022191033A1
Application number: PCT/JP2022/009147
Authority: WO
Inventors: 謙一福田; 慎也萩原
Original assignee: 住友化学株式会社
Priority date: 2021-03-11
Filing date: 2022-03-03
Publication date: 2022-09-15
Also published as: CN116888511A; JP2022138876A; TW202248681A; KR20230154893A

Abstract

The present invention provides a polarizing plate that has excellent scratch resistance and suppresses the formation of cracks in a phase difference film even when stored for a long period of time in a normal-temperature and normal-humidity environment after being subjected to a thermal durability test. The polarizing plate comprises: a polarizing film in which a dichroic pigment has been adsorbed and oriented on a polyvinyl alcohol resin film; a protective film in which a hard coat layer is provided on top of a base film; and the phase difference film which has a tensile elastic modulus at a temperature of 23°C of 3000 MPa or less. Two or more protective films are layered on a first-surface side of the polarizing film. The phase difference film is layered on a second-surface side of the polarizing film, said second-surface side being the reverse side from the first surface.

Description

Polarizer

The present invention relates to a polarizing plate, and further to a display device equipped with a polarizing plate.

Liquid crystal display devices (LCDs) are widely used not only for liquid crystal televisions, but also for mobile applications such as personal computers and mobile phones, and in-vehicle applications such as car navigation systems. Generally, a liquid crystal display device has a liquid crystal panel member in which polarizing plates are adhered to both sides of a liquid crystal cell with an adhesive, and display is performed by controlling light from a backlight member with the liquid crystal panel member. In recent years, like liquid crystal display devices, organic EL display devices have begun to be widely used in mobile applications such as televisions and mobile phones, and in-vehicle applications such as car navigation systems. In liquid crystal display devices and organic EL display devices, a retardation film is sometimes used in order to impart functions such as widening of the viewing angle or prevention of reflection of external light.

Polarizing plates are increasingly used in vehicles as optical elements that make up liquid crystal display devices and organic EL display devices. Compared to polarizing plates used in mobile applications such as televisions and mobile phones, polarizing plates used in in-vehicle display devices are often exposed to high-temperature environments and their properties change less at higher temperatures. (high temperature durability) is required.

In-vehicle display devices require a touch panel function when used in car navigation systems. In recent years, on-cell and in-cell display devices have been increasingly used as display devices having a touch panel function. In these types of display devices, since the polarizing plate is arranged on the outermost surface on the viewing side, a scratch-preventing function (scratch resistance) is required in addition to high-temperature durability.

Patent Document 1 describes a polarizing plate including a retardation film made of a cyclic olefin resin film in order to expand the viewing angle. Moreover, Patent Document 2 describes that a film using a cyclic olefin resin may be used as a retardation film functioning as a λ/4 plate constituting a polarizing plate.

Japanese Patent No. 5383594 JP 2014-194483 A

Like the retardation film made of the above-mentioned cyclic olefin resin film, the retardation film incorporated in the polarizing plate, even if no cracks were confirmed after the heat durability test, was further tested at room temperature and normal humidity. When stored in an environment for a long period of time, cracks were observed in some cases.

An object of the present invention is to provide a polarizing plate that has excellent scratch resistance and that suppresses the occurrence of cracks in the retardation film even when stored for a long period of time under normal temperature and humidity after a heat durability test.

The present invention provides the following polarizing plate.
[1] A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film;
a protective film in which a hard coat layer is provided on a base film;
A retardation film having a tensile modulus of elasticity of 3000 MPa or less at a temperature of 23 ° C.,
Two or more of the protective films are laminated on the first surface side of the polarizing film,
A polarizing plate, wherein the retardation film is laminated on a second surface side opposite to the first surface side of the polarizing film.
[2] Among the two or more protective films laminated on the first surface side, at least one protective film has a moisture permeability at a temperature of 40°C and a relative humidity of 90% of 200 g/m ² day or more. The polarizing plate of [1].
[3] Among the two or more protective films laminated on the first surface side, the protective film laminated closest to the polarizing film has a moisture permeability of 200 g/m ² at a temperature of 40°C and a relative humidity of 90%. - The polarizing plate according to [1] or [2], which is at least day.
[4] Any one of [1] to [3], wherein the base film of at least one of the two or more protective films laminated on the first surface side is a cellulose resin film. The polarizing plate described in .
[5] The polarizing plate according to any one of [1] to [4], wherein the retardation film is a cyclic olefin resin film.
[6] The polarizing plate of any one of [1] to [5], wherein the retardation film has an in-plane retardation value of 80 nm or more at a wavelength of 550 nm.
[7] The polarizing plate of any one of [1] to [6], further comprising an adhesive layer on the side of the retardation film opposite to the polarizing film side.
[8] A display device comprising the polarizing plate of [7] and a display element,
The display device, wherein the polarizing plate is laminated on a display element via the pressure-sensitive adhesive layer.

According to the present invention, it is possible to provide a polarizing plate that has excellent scratch resistance and that suppresses the occurrence of cracks in the retardation film even after being stored for a long period of time under normal temperature and humidity conditions after a heat durability test.

1 is a schematic cross-sectional view showing a polarizing plate according to one embodiment of the present invention; FIG.

Preferred embodiments of the polarizing plate and the display device will be described below with reference to the drawings.
(Polarizer)
FIG. 1 is a schematic cross-sectional view showing a polarizing plate according to this embodiment. The polarizing plate 1 includes a polarizing film 11 in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film (hereinafter sometimes referred to as a "PVA-based resin film"), and a hard coat layer ( hereinafter sometimes referred to as “HC layer”), and a retardation film 21 having a tensile elastic modulus of 3000 MPa or less at a temperature of 23°C. As shown in FIG. 1, in the polarizing plate 1, two or more

protective films

12 and 13 are laminated on the first surface 11a side of the polarizing film 11, and the

protective films

12 and 13 are laminated on the side opposite to the first surface 11a side of the polarizing film 11. A retardation film 21 is laminated on the second surface 11b side.

As described above, the polarizing plate 1 has two or more

protective films

12 and 13 including HC layers laminated on the first surface 11a side of the polarizing film 11 . As a result, the pencil hardness of the surface of the polarizing plate 1 on the side of the

protective films

12 and 13 can be improved, so that the polarizing plate 1 can be provided with excellent scratch resistance.

After the polarizing plate 1 was subjected to a heat endurance test in which it was held at a temperature of 105°C for 500 hours, even if it was held in a normal temperature and normal humidity environment at a temperature of 23°C and a relative humidity of 55% for about one month, the retardation film 21 cracked. It is possible to suppress the occurrence of (cracks). The reason for this is presumed as follows. When the polarizing plate 1 is cooled after the heating endurance test and kept in a normal temperature and normal humidity environment, moisture (water vapor) in the atmosphere is easily taken into the polarizing plate. Moisture taken into the polarizing plate causes dimensional change of the polarizing film including the PVA-based resin film. It is considered that when the force generated by the dimensional change of the polarizing film acts on the retardation film, cracks may occur in the retardation film. On the other hand, since the polarizing plate 1 has two or more

protective films

12 and 13 laminated on the first surface 11a side of the polarizing film 11, the amount of moisture taken into the polarizing plate 1 can be reduced. A dimensional change of the polarizing film 11 can be suppressed. Therefore, it is presumed that the force acting on the retardation film 21 provided on the second surface 11b side of the polarizing film 11 can be reduced, and the occurrence of cracks in the retardation film 21 can be suppressed. .

Each film constituting the polarizing plate 1 can be laminated via bonding layers 31 to 33 as shown in FIG. The lamination layers 31 to 33 are layers using an adhesive or pressure-sensitive adhesive. The bonding layer 31 for bonding the protective film 12 and the protective film 13 is preferably a layer using an adhesive. Both the bonding layer 32 for bonding the protective film 13 and the polarizing film 11 and the bonding layer 33 for bonding the polarizing film 11 and the retardation film 21 are layers using an adhesive. is preferably

The polarizing plate 1 further includes an antistatic layer, another retardation layer different from the retardation film 21, another protective layer different from the

protective films

12 and 13 for protecting the surface of the polarizing film 11, etc. may have a functional layer of

The polarizing plate 1 can be used as an optical element that constitutes a display device. Therefore, the polarizing plate 1 may have an adhesive layer 35 (FIG. 1) for bonding the polarizing plate 1 to a display element of a display device or the like. The polarizing plate 1 may further have a release film that covers and protects the pressure-sensitive adhesive layer 35 and that can be peeled off the pressure-sensitive adhesive layer 35 .

(Display device)
The display device can include a polarizing plate 1 and a display element such as a liquid crystal cell or an organic electroluminescence (EL) element. In the display device, the polarizing plate 1 can be arranged so that the second surface 11b side of the polarizing film 11 faces the display element side. The polarizing plate 1 may be laminated on the display element via the adhesive layer 35 shown in FIG. Just do it. Examples of display devices include liquid crystal display devices and organic EL devices.

The films and layers constituting the polarizing plate 1 will be described in detail below.
(polarizing film)
The polarizing film 11 is an absorptive polarizing film having a property of absorbing linearly polarized light having a plane of vibration parallel to its absorption axis and transmitting linearly polarized light having a plane of vibration perpendicular to the absorption axis (parallel to the transmission axis). is. As the polarizing film 11, a film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched PVA-based resin film can be preferably used.

The thickness of the polarizing film 11 is usually 50 µm or less, preferably 5 µm or more and 30 µm or less, more preferably 5 µm or more and 25 µm or less, and still more preferably 5 µm or more and 20 µm or less. By setting the thickness of the polarizing film 11 within these ranges, the polarizing film 11 can be prevented from being broken, cracked, or the like during production, and can maintain good optical properties at the same time. By setting the thickness of the polarizing film to 20 μm or less, it is possible to further suppress deterioration in visibility when placed in a high-temperature environment.

The polarizing film 11 is formed by, for example, a process of stretching a PVA-based resin film; a process of dyeing the PVA-based resin film with a dichroic dye to adsorb the dichroic dye; and a PVA-based resin to which the dichroic dye is adsorbed. It can be produced by a method comprising a step of treating the film with a cross-linking solution such as an aqueous boric acid solution; and a step of washing with water after the step of treating with the cross-linking solution.

For the PVA-based resin film, it is possible to use a film made of polyvinyl alcohol-based resin (hereinafter sometimes referred to as "PVA-based resin"). Examples of PVA-based resins include saponified polyvinyl acetate-based resins. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers that can be copolymerized. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group. As used herein, "(meth)acryl" means at least one selected from acryl and methacryl. The same applies to "(meth)acryloyl", "(meth)acrylate" and the like.

The degree of saponification of the PVA-based resin is usually 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The PVA-based resin may be modified, for example, aldehyde-modified polyvinyl formal or polyvinyl acetal may be used. The average degree of polymerization of the PVA-based resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less. The average degree of polymerization of the PVA-based resin can be obtained according to JIS K 6726.

The method of forming a PVA-based resin film is not particularly limited, and a known method is adopted. There is no particular limitation on the thickness of the PVA-based resin film used for the raw film when producing the polarizing film. For example, in order to set the thickness of the polarizing film to 25 μm or less, the thickness of the PVA-based resin film as the raw film is preferably 40 μm or more and 75 μm or less, and more preferably 45 μm or less.

The stretching of the PVA-based resin film is preferably uniaxial stretching. Uniaxial stretching can be performed before, at the same time as, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the cross-linking treatment. Moreover, you may uniaxially stretch in these several steps. In the uniaxial stretching, the film may be uniaxially stretched between rolls having different circumferential speeds, or may be uniaxially stretched using hot rolls. The uniaxial stretching may be dry stretching in which the film is stretched in the air, or wet stretching in which the PVA-based resin film is stretched in a swollen state using a solvent or water. The draw ratio is usually 3 to 8 times.

As a method for dyeing a PVA-based resin film with a dichroic dye, for example, a method of immersing the PVA-based resin film in an aqueous solution containing a dichroic dye is adopted. Iodine and dichroic organic dyes are used as dichroic dyes. The PVA-based resin film is preferably immersed in water before being dyed.

As a cross-linking treatment after dyeing with a dichroic dye, a method of immersing the dyed PVA-based resin film in an aqueous solution containing boric acid is usually adopted. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide.

(Protective film)

Protective films

12 and 13 have a base film and an HC layer. It is preferable that the

protective films

12 and 13 have an HC layer formed so as to be in direct contact with the base film.
The HC layer is preferably provided on one side of the base film, but may be provided on both sides.

The

protective films

12 and 13 laminated on the first surface 11a side of the polarizing film 11 (hereinafter, two or more protective films laminated on the first surface 11a side may be collectively referred to as a "protective film group"). , is preferably 5 or less, more preferably 3 or less, and most preferably 2. When the protective film group includes 6 or more protective films, it becomes difficult to adjust the curl (warp) of the polarizing plate 1 . As shown in FIG. 1, the

protective films

12 and 13 constituting the protective film group are preferably laminated via a bonding layer 31, and both surfaces of the bonding layer 31 constitute the protective film group. More preferably, it is in direct contact with

protective films

12 and 13 . In each of the

protective films

12 and 13 constituting the protective film group, in the polarizing plate 1, the base film is arranged on the polarizing film 11 side, and the HC layer is on the surface side of the polarizing plate 1 (the side opposite to the polarizing film 11 side). ).

Although the thickness of the protective film is not particularly limited, it is usually 1 μm or more and 100 μm or less, preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 55 μm or less, and 15 μm or more and 50 μm or less from the viewpoint of strength and handleability. is more preferable.

One or both of the material and thickness of the base film and the HC layer may be the same for the

protective films

12 and 13 constituting the protective film group. may be different from each other.

At least one protective film in the protective film group preferably has a moisture permeability of 200 g/m ² ·day or more at a temperature of 40°C and a relative humidity of 90%, more preferably 300 g/m ² ·day or more. Preferably, the upper limit is usually 5000 g/m ² ·day or less, preferably 2000 g/m ² ·day or less, more preferably 1000 g/m ² ·day or less. In the polarizing plate 1, at least one protective film in the group of protective films should have a moisture permeability within the above range. By setting the moisture permeability of the protective film within the above range, it is possible to prevent the polarizing film 11 from becoming polyene and being colored in the heating endurance test described later.

It is preferable that the protective film 12 laminated closest to the polarizing film in the group of protective films has a moisture permeability within the above range. When manufacturing the polarizing plate 1, as will be described later, after bonding the protective film 12 to the polarizing film 11 using a bonding agent (adhesive or adhesive) such as a water-based adhesive, the bonding layer is dried by drying. 32 and then a protective film 13 may be laminated. In this case, by setting the moisture permeability of the protective film 12, which is laminated closest to the polarizing film 11 among the protective films, to the above range, the moisture contained in the bonding agent can be easily removed by the drying process.

If the protective film 12 laminated closest to the polarizing film 11 in the protective film group has a moisture permeability within the above range, the moisture permeability of the other protective films 13 other than the protective film 12 included in the protective film group is not particularly limited. The moisture permeability of the other protective film 13 may be lower than the moisture permeability of the protective film 12 . The moisture permeability of the other protective film 13 at a temperature of 40° C. and a relative humidity of 90% is not particularly limited, but is preferably 1000 g/m ² ·day or less, more preferably 500 g/m ² ·day or less. . The moisture permeability of the protective film 13 is preferably more than 20 g/m ² ·day, more preferably 30 g/m ² ·day or more. By setting the upper limit value of the moisture permeability of the other protective film 13 within the above range, it is possible to suppress the rate at which moisture is taken into the polarizing plate 1 after the heat durability test. As a result, it becomes easier to secure time for stress relaxation of the polarizing film 11 , so it is thought that the occurrence of cracks in the retardation film 21 can be suppressed. By setting the lower limit value of the moisture permeability of the other protective film 13 within the above range, it is possible to suppress the polarizing film 11 from polyene-forming and coloring in the heat durability test. The moisture permeability of the

protective films

12 and 13 can be measured by the method described in Examples below.

In the above description, the moisture permeability of the protective film 12 is 200 g/m ² ·day or more, and the moisture permeability of the other protective film 13 is 1000 g/m ² ·day or less. Even when the relationship is reversed, it is possible to prevent the polarizing film 11 from becoming polyene and coloring due to the heating endurance test.

The base film that constitutes the

protective films

12 and 13 is not particularly limited, but is preferably made of a resin material that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, and the like. Examples of such resin materials include (meth)methyl acrylate-based resins, polyolefin-based resins, cyclic olefin-based resins, polyvinyl chloride-based resins, cellulose-based resins, styrene-based resins, acrylonitrile-butadiene-styrene-based resins, Acrylonitrile/Styrene Resin, Polyvinyl Acetate Resin, Polyvinylidene Chloride Resin, Polyamide Resin, Polyacetal Resin, Polycarbonate Resin, Modified Polyphenylene Ether Resin, Polybutylene Tephthalate Resin, Polyethylene Tephthalate Resin, Polysulfone one or more of polyethersulfone-based resins, polyarylate-based resins, polyamideimide-based resins, polyimide-based resins, and the like. These resins may be used after undergoing any suitable polymer modification. Polymer modification includes, for example, copolymerization, cross-linking, molecular terminal modification, stereoregularity control, and modification such as mixing including reactions involving different types of polymers.

The base film of at least one protective film in the group of protective films is preferably a cellulose resin film formed using a cellulose resin as a resin material. It is more preferable that the base films of all the protective films constituting the protective film group are cellulose resin films.

The cellulosic resin can be an organic acid ester or mixed organic acid ester of cellulose in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are substituted with acetyl groups, propionyl groups and/or butyryl groups. Examples thereof include cellulose acetate, propionate, butyrate, and mixed esters thereof. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like are preferable.

Appropriate additives may be added to the resin material constituting the base film as long as the transparency is not impaired. Additives such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, retardation reducing agents, stabilizers, processing aids, plasticizers, impact resistance aids , matting agents, antibacterial agents, antifungal agents, and the like. One or more of these additives may be used, and multiple types may be used in combination.

The thickness of the base film is not particularly limited, but may be, for example, 1 μm or more, 3 μm or more, 10 μm or more, 30 μm or more, and usually 90 μm or less. and may be 70 μm or less, 60 μm or less, or 50 μm or less. The substrate film usually has a single-layer structure, but may have a multi-layer structure of two or more layers.

Although the HC layer that constitutes the

protective films

12 and 13 is not particularly limited, it is preferably a cured product layer of an ultraviolet curable resin formed on the base film. Examples of UV curable resins include (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The HC layer may contain additives to improve surface hardness. Examples of additives include, but are not limited to, inorganic fine particles, organic fine particles, and mixtures thereof.

The thickness of the HC layer is preferably 10 μm or less, more preferably 8 μm or less, usually 0.1 μm or more, may be 1 μm or more, or may be 4 μm or more. When the thickness of the HC layer exceeds 10 μm, the curl (warp) of the

protective films

12 and 13 increases, making it difficult to adjust the curl of the polarizing plate 1 .

The

protective films

12 and 13 have a pencil hardness specified in JIS K 5600-5-4: 1999 "Paint general test method-Part 5: Mechanical properties of coating film-Section 4: Scratch hardness (pencil method)" According to the test (when the base film with the HC layer formed thereon is placed on a glass plate and the HC layer side is measured), it is preferably H or more, more preferably 2H or more, and 3H or more. It may be 4H or more.

The HC layer is, for example, a composition for forming an HC layer containing an ultraviolet curable resin and, if necessary, additives (hereinafter sometimes referred to as "composition for forming an HC layer") on a base film. ) and cured by UV irradiation.

(retardation film)
The retardation film 21 is a film having retardation, and is usually a stretched film obtained by stretching a resin film. The retardation film 21 preferably has a single layer structure. The tensile elastic modulus of the retardation film 21 at a temperature of 23° C. is 3000 MPa or less, and may be 2800 MPa or less, usually 1000 MPa or more, and may be 2000 MPa or more. The tensile modulus can be measured by the method described in Examples below.

Examples of the retardation film 21 having the above tensile modulus include an olefin-based resin film formed using an olefin-based resin. Olefin-based resins include linear aliphatic olefins such as ethylene and propylene, or alicyclic olefins such as norbornene and its substituted products (hereinafter collectively referred to as "norbornene-based monomers"). Examples include resins mainly containing derived structural units. Mainly containing structural units means that the proportion of the structural units contained in the resin is 50% or more based on the amount of substance. The olefinic resin may be a copolymer using two or more monomers.

The retardation film 21 is preferably a cyclic olefin-based resin film formed using a cyclic olefin-based resin, which is a resin mainly containing structural units derived from an alicyclic olefin. Typical examples of alicyclic olefins constituting cyclic olefin resins include norbornene-based monomers. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and according to the IUPAC nomenclature, it is named bicyclo[2,2,1]hept-2-ene. be. Examples of substituted norbornene include 3-substituted, 4-substituted, and 4,5-disubstituted, with the double bond position of norbornene being 1,2-position, and further Also included are dicyclopentadiene and dimethanooctahydronaphthalene.

The cyclic olefin resin may or may not have a norbornane ring in its constituent units. Examples of norbornene-based monomers that form cyclic olefin-based resins that do not have a norbornane ring in their constituent units include, for example, those that become 5-membered rings by ring opening, typically norbornene, dicyclopentadiene, 1- or 4- Examples include methylnorbornene, 4-phenylnorbornene, and the like. When the cyclic olefin resin is a copolymer, the arrangement state of its molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a polymer.

More specific examples of cyclic olefin resins include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers, maleic acid addition, cyclopentadiene addition, and the like. modified polymers, and hydrogenated polymers or copolymers thereof; addition polymers of norbornene-based monomers, addition copolymers of norbornene-based monomers and other monomers, and the like. Other monomers in the case of copolymerization include α-olefins, cycloalkenes, non-conjugated dienes, and the like. Moreover, the cyclic olefin-based resin may be a copolymer using one or more of norbornene-based monomers and other alicyclic olefins. Among these, as the cyclic olefin-based resin, a ring-opening polymer or a resin obtained by hydrogenating a ring-opening copolymer using a norbornene-based monomer is preferable.

Commercial products of the cyclic olefin resin using the above norbornene-based monomers are all trade names of "ZEONEX" and "ZEONOR" sold by Nippon Zeon Co., Ltd., and sold by JSR Corporation. "Arton" etc. are mentioned. Films of these cyclic olefin resins and stretched films thereof are also commercially available. and "Escina" from Sekisui Chemical Co., Ltd.;

As the retardation film 21, a film made of a mixed resin containing two or more kinds of olefinic resins, or a film made of a mixed resin of an olefinic resin and another thermoplastic resin can be used. For example, mixed resins containing two or more kinds of olefinic resins include mixtures of cyclic olefinic resins and linear aliphatic olefinic resins as described above. When using a mixed resin of an olefinic resin and another thermoplastic resin, the other thermoplastic resin is appropriately selected depending on the purpose. Specific examples of other thermoplastic resins include polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile/butadiene/styrene copolymer resins, acrylonitrile/styrene copolymer resins, (meth)acrylic resins, and polyacetic acid. Vinyl resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyether Examples include sulfone-based resins, polyetheretherketone-based resins, polyarylate-based resins, liquid-crystalline resins, polyamide-imide-based resins, polyimide-based resins, and polytetrafluoroethylene-based resins. These thermoplastic resins may be used alone or in combination of two or more. Moreover, the thermoplastic resin can be used after being subjected to any appropriate polymer modification. Examples of polymer modification include copolymerization, cross-linking, molecular terminal modification, stereoregularity impartation, and the like.

When using a mixed resin of an olefin resin and another thermoplastic resin, the content of the other thermoplastic resin is usually about 50% by weight or less, preferably about 40% by weight or less, based on the total resin. By setting the content of the other thermoplastic resin within this range, the retardation film has a small absolute value of the photoelastic coefficient, exhibits good wavelength dispersion characteristics, and is excellent in durability, mechanical strength, and transparency. 21 can be obtained.

The retardation film 21 may contain other components such as residual solvents, stabilizers, plasticizers, anti-aging agents, anti-static agents, and ultraviolet absorbers as necessary. A leveling agent may also be included to reduce surface roughness.

The retardation film 21 preferably has an in-plane retardation value, and the in-plane retardation value at a wavelength of 550 nm is preferably 80 nm or more, may be 90 nm or more, or may be 100 nm or more, Moreover, it may be 300 nm or less, or may be 200 nm or less. The retardation film 21 is preferably a stretched film.

Generally, the higher the in-plane retardation value of the retardation film 21, the more aligned the molecular orientation of the retardation film 21, and the more likely it is to crack when subjected to an external force. As described above, the polarizing plate 1 has a structure in which two or more

protective films

12 and 13 are laminated on the first surface 11 a of the polarizing film 11 . Therefore, even when the polarizing plate 1 including the retardation film 21 having a high in-plane retardation value as described above is held for a long time under normal temperature and humidity environment after the heat durability test, the dimensions of the polarizing film 11 Since the change can be suppressed and the force acting on the retardation film 21 can be reduced accordingly, the generation of cracks in the retardation film 21 can be suppressed.

The in-plane retardation value of the retardation film 21 can be measured by the method described in Examples below. The in-plane retardation value Re(λ) of the retardation film 21 at the wavelength λ [nm] refers to the in-plane retardation value of the retardation film 21 at a temperature of 23° C., and is obtained by the following formula (i).
Re(λ)=(nx−ny)×d(i)
[in the formula (i),
nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction),
ny is the refractive index in the direction perpendicular to the slow axis in the plane,
d is the thickness [nm] of the retardation film 21 . ]

The retardation film 21 may have a retardation value of 0 (zero) in the thickness direction, or may have a retardation value in the thickness direction. The thickness direction retardation value of the retardation film 21 at a wavelength of 550 nm may be, for example, 10 nm or more, 20 nm or more, 40 nm or more, or 100 nm or less. , 80 nm or less, or 60 nm or less. The retardation value in the thickness direction of the retardation film 21 can be measured by the method described in Examples below. The retardation value Rth(λ) in the thickness direction of the retardation film 21 at the wavelength λ [nm] refers to the retardation value in the thickness direction of the retardation film 21 at a temperature of 23° C., and is obtained by the following formula (ii).
Rth(λ)=[{(nx+ny)/2}-nz]×d (ii)
[In the formula (ii),
nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction),
ny is the refractive index in the direction perpendicular to the slow axis in the plane,
nz is the refractive index in the thickness direction,
d is the thickness [nm] of the retardation film 21 . ]

Although the thickness of the retardation film 21 is not particularly limited, it is preferably 15 μm or more and 80 μm or less, more preferably 18 μm or more and 45 μm or less, and most preferably 20 μm or more and 30 μm or less. When the thickness of the retardation film is less than 15 μm, it tends to be difficult to handle the film and to exhibit a predetermined retardation value. On the other hand, when the thickness of the retardation film exceeds 80 μm, the processability tends to be poor, the transparency tends to decrease, and the weight of the obtained polarizing plate 1 tends to increase.

The retardation film 21 can be obtained by using a resin film formed using the resin described above and stretching it. The resin film can be obtained, for example, by forming a film from a solution containing the above-described olefinic resin by a casting method, a melt extrusion method, or the like. When a film is formed using a mixed resin of two or more kinds, the film forming method is not particularly limited. Examples include a method of producing a film by a casting method, and a method of producing a film by melt-extrusion by melt-mixing resin components in a predetermined ratio.

Examples of the stretching treatment of the resin film include known vertical uniaxial stretching, tenter horizontal uniaxial stretching, simultaneous biaxial stretching, and sequential biaxial stretching. In the stretching process, in addition to appropriately adjusting the stretching ratio and stretching speed so as to obtain a desired retardation value, various temperatures such as preheating temperature, stretching temperature, heat setting temperature, cooling temperature, etc. during stretching, and The pattern may be appropriately selected.

When the retardation film 21 is the cyclic olefin-based resin film described above, for example, a film-like material that has been subjected to stretching treatment in advance using the cyclic olefin-based resin described above, and a shrinkable film having a predetermined shrinkage rate is obtained. can be obtained by bonding and heat-shrinking. Thereby, a retardation film 21 having high uniformity and a large retardation value can be obtained.

(functional layer)
The polarizing plate 1 includes an antistatic layer, another retardation layer different from the retardation film 21, and another protective layer different from the

protective films

12 and 13 for covering and protecting the surface of the polarizing film 11. It may have one or more functional layers.

The antistatic layer is a layer for suppressing the polarizing plate 1 from being charged. The antistatic layer usually contains an antistatic agent such as an ionic compound, and can be, for example, a layer containing an antistatic agent and a resin. The antistatic layer is, for example, in the polarizing plate 1, between the polarizing film 11 and the retardation film 21, or between the polarizing film 11 and the protective film 12, the opposite side of the retardation film 21 from the polarizing film 11, etc. can be set to The antistatic layer is preferably laminated on these films via a lamination layer.

Another retardation layer is a layer having an in-plane retardation value or a retardation value in the thickness direction. The other retardation layer may be, for example, a retardation layer having a retardation value in the thickness direction at a wavelength of 550 nm, such as a positive C plate. A positive C plate is used, for example, when the polarizing plate 1 is used in an IPS mode liquid crystal display device or the like. Another retardation layer can be provided, for example, between the polarizing film 11 and the retardation film 21 or on the side of the retardation film 21 opposite to the polarizing film 11 side. The other retardation layer may be a stretched film obtained by stretching a resin film, or may be a cured product layer of a polymerizable liquid crystal compound. Another retardation layer can be laminated on the polarizing film 11 and the retardation film 21 via a bonding layer. When the other retardation layer is a cured product layer, by polymerizing and curing the polymerizable liquid crystal compound applied to the polarizing film 11 or the retardation film 21, it can be provided so as to be in direct contact with these films.

Another protective layer is a layer for covering and protecting the first surface 11 a or the second surface 11 b of the polarizing film 11 . Another protective layer is provided on the second surface 11b side of the polarizing film 11, and is preferably provided between the polarizing film 11 and the retardation film 21 via a bonding layer.
In this case, the bonding layer provided between the polarizing film 11 and the other protective layer is provided so as to be in contact with the polarizing film 11 and the other protective layer, respectively, and between the other protective layer and the retardation film 21 It is preferable that the lamination layer provided in 1 is provided so as to be in contact with the other protective layer and the retardation film 21 respectively. Another protective layer includes a film formed using the resin material described in the base film forming the

protective films

12 and 13 . The other protective layer preferably has no retardation, and examples thereof include a cellulose resin film having no retardation and a cyclic olefin resin film having no retardation.

(Lamination layer)
As the bonding layers 31 to 33 for bonding each film and each layer constituting the polarizing plate 1, a layer formed using a known adhesive, or a layer formed using a known pressure-sensitive adhesive. is mentioned.

The adhesive is an adhesive other than a pressure-sensitive adhesive (adhesive), and includes, for example, a water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive, preferably a water-based adhesive, It is an active energy ray-curable adhesive. The thickness of the lamination layer formed using an adhesive may be, for example, 0.01 μm or more, 0.1 μm or more, 0.5 μm or more, or 1 μm or more. For example, it may be 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less.

Examples of water-based adhesives include adhesives made from aqueous solutions of polyvinyl alcohol-based resins, water-based two-liquid urethane-based emulsion adhesives, and the like. Among them, a water-based adhesive composed of an aqueous polyvinyl alcohol resin solution is preferably used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, or a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl groups thereof can be used. The water-based adhesive can contain cross-linking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, polyvalent metal salts, and the like.

When using a water-based adhesive as the adhesive, it is preferable to carry out a drying process to remove the water contained in the water-based adhesive after lamination with the film to be laminated. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45°C may be provided.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with an active energy ray such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet curable adhesive. be. The curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of cationic polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule) and oxetane compounds (one or two or more oxetane rings in the molecule). compound), or a combination thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule) and radically polymerizable double bonds. Other vinyl-based compounds or combinations thereof can be included. A cationic polymerizable curable compound and a radically polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and/or a radical polymerization initiator for initiating the curing reaction of the curable compound.

A pressure-sensitive adhesive exhibits adhesiveness when it is attached to an adherend, and is called a pressure-sensitive adhesive. The adhesive can be composed of an adhesive composition containing a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin as a main component. Among them, a pressure-sensitive adhesive composition using a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The adhesive may be active energy ray-curable or thermosetting. The thickness of the lamination layer formed using the adhesive is usually 3 μm or more and 30 μm or less, preferably 3 μm or more and 25 μm or less.

The (meth)acrylic resin (base polymer) contained in the adhesive composition includes, for example, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, 2-(meth)acrylate, Polymers or copolymers containing one or more of (meth)acrylic acid esters such as ethylhexyl as monomers are preferably used. Preferably, the base polymer is copolymerized with a polar monomer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as meth)acrylates, can be mentioned.

The adhesive composition may contain only the above base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a metal ion having a valence of 2 or more, which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound, which forms an amide bond with a carboxyl group; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

(Adhesive layer)
The polarizing plate 1 may have an adhesive layer 35 for bonding the polarizing plate 1 to a display element of a display device or the like. The pressure-sensitive adhesive layer 35 is preferably provided on the side of the retardation film 21 of the polarizing plate 1 opposite to the polarizing film 11 side. The adhesive layer 35 can be formed using an adhesive. Examples of the adhesive include the adhesive used for forming the bonding layer. Although the thickness of the adhesive layer 35 is not particularly limited, it is usually 3 μm or more and 50 μm or less, preferably 5 μm or more and 40 μm or less, and may be 10 μm or more and 30 μm or less.

(Release film)
The polarizing plate 1 may have a release film that can be separated from the adhesive layer 35 . The release film is used to cover and protect the surface of the adhesive layer 35 or to support the adhesive layer 35 . Examples of the release film include a film obtained by subjecting the surface of the base resin film on the pressure-sensitive adhesive layer 35 side to release treatment such as silicone treatment. Examples of the resin material that constitutes the base resin film include films formed using the resin materials described above for the base film. The base resin film may have a one-layer structure or a multi-layer structure of two or more layers.

(Manufacturing method of polarizing plate)
A method for manufacturing the polarizing plate 1 is not particularly limited, and a known method can be used. For example, the protective film 12 is laminated on the first surface 11a of the polarizing film 11 using a water-based adhesive, and the retardation film 21 is laminated on the second surface 11b of the polarizing film 11 using a water-based adhesive. A laminate of protective film 12/bonding layer 32/polarizing film 11/bonding layer 33/retardation film 21 is produced through a drying process for removing water in the agent. At this time, if the thickness difference between the protective film 12 and the retardation film 21 is 30 μm or less, curling of the laminate can be easily suppressed, and a flat laminate can be easily obtained. After that, the polarizing plate 1 can be obtained by laminating the protective film 13 on the protective film 12 side of the laminate with the bonding layer 31 interposed therebetween. When the polarizing plate 1 has three or more protective films on the first surface 11a side of the polarizing film 11, a step of laminating the protective films may be provided. As described above, when a laminate having a thickness difference of 30 μm or less between the protective film 12 and the retardation film 21 is used, curling occurring in the polarizing plate 1 can be easily suppressed, and a flat polarizing plate 1 can be obtained. easy to get

In order to increase the adhesiveness between the films and layers (

protective films

12, 13, polarizing film 11, retardation film 21, functional layer, etc.) constituting the polarizing plate 1 and the bonding layer, these films and layers are bonded together. A surface activation treatment may be applied to the surface. Surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.). ; ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and wet treatment such as anchor coating treatment. These surface activation treatments may be performed singly or in combination of two or more.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Thickness measurement]
The thickness of each film and each layer constituting the polarizing plate was measured using a digital micrometer MH-15M manufactured by Nikon Corporation.

[Measurement of moisture permeability]
The moisture permeability of the protective film was measured in accordance with JIS K 7129:2008 Appendix B in an atmosphere at a temperature of 40°C and a relative humidity of 90%.

[Measurement of phase difference value]
The retardation values of the retardation film and other retardation layers were measured using a retardation measuring device KOBRA-WPR (manufactured by Oji Scientific Instruments Co., Ltd.).

[Measurement of tensile modulus]
A test piece having a width of 15 mm and a length of 150 mm was cut out from the retardation film parallel to the slow axis and the fast axis. Next, the upper and lower grips of a tensile tester (AUTOGRAPH (registered trademark) AG-1S tester manufactured by Shimadzu Corporation) were held at both ends in the long side direction of the test piece so that the distance between the grips was 100 mm. . A stress-strain curve was created by pulling at a tensile speed of 50 mm/min in an environment of 23°C. Based on the stress-strain curve, the tensile elastic modulus in the direction parallel to the slow axis and fast axis at 23° C. was calculated. Of the tensile elastic moduli in the direction parallel to the slow axis and the fast axis thus calculated, the one with the largest value was taken as the value of the tensile elastic modulus at 23°C of the retardation film.

[Measurement of storage modulus]
The storage elastic moduli G' of the adhesive layer A and the adhesive layer B were measured according to the procedures [I] to [III] below.
[I] Two samples are taken out from each pressure-sensitive adhesive layer so that each weighs 25±1 mg, and each sample is formed into a ball shape.
[II] Two molded approximately ball-shaped samples are attached to the upper and lower surfaces of an I-shaped jig, respectively, and both upper and lower surfaces are sandwiched between L-shaped jigs to obtain measurement samples. The configuration of the measurement sample is L-shaped jig/adhesive layer A or adhesive layer B/I-shaped jig/adhesive layer/L-shaped jig.
[III] The storage elastic modulus G' of the measurement sample is measured using a dynamic viscoelasticity measuring device "DVA-220" manufactured by IT Keisoku Co., Ltd. under the conditions of a temperature of 23 ° C., a frequency of 1 Hz, and an initial strain of 1 N. Measure in

[Measurement of pencil hardness]
The protective film was placed on the glass plate so that the substrate film side of the protective film faced the glass plate. For the HC layer side of the protective film, a pencil specified in JIS K 5600-5-4: 1999 "General test method for paint-Part 5: Mechanical properties of coating film-Section 4: Scratch hardness (pencil method)" A hardness test was performed to measure the pencil hardness of the protective film.

<Preparation of polarizing film>
A 40 μm-thick PVA-based resin film made of a PVA-based resin having an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol % or more was prepared. This PVA-based resin film was uniaxially stretched about 5 times by a dry method, and further immersed in pure water at a temperature of 60° C. for 1 minute while maintaining the tension. After that, the PVA-based resin film was immersed in an aqueous solution of iodine/potassium iodide/water at a weight ratio of 0.05/5/100 at a temperature of 28° C. for 60 seconds. After that, the PVA-based resin film was immersed in an aqueous solution of potassium iodide/boric acid/water at a weight ratio of 8.5/8.5/100 at a temperature of 72° C. for 300 seconds. Subsequently, it was washed with pure water at a temperature of 26°C for 20 seconds and then dried at a temperature of 65°C.
Thus, a polarizing film having a thickness of 15 μm was obtained in which iodine as a dichroic dye was adsorbed and oriented on the PVA-based resin film.

<Preparation of protective film (1)>
A composition for forming an HC layer was prepared by mixing the components shown below.
PET30 97.0 parts by mass Irgacure 907 3.0 parts by mass MEK 81.8 parts by mass PET30 is a mixture of pentaerythritol tetraacrylate and pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd.).
Irgacure 907 is a photopolymerization initiator (manufactured by BASF).
MEK is methyl ethyl ketone.

A base film (cellulose acylate film TD40, manufactured by Fujifilm Corporation, width 1,340 mm, film thickness 40 μm) wound in a roll is unwound and transported at a speed of 30 m/min by a die coating method using a slot die. and dried at 60° C. for 150 seconds to form a coating layer. Then, under a nitrogen purge and an oxygen concentration of about 0.1%, an air-cooled metal halide lamp (manufactured by Eyegraphic Co., Ltd.) with an output of 160 W/cm was used to set an illuminance of 400 mW/cm ² and an irradiation dose of 120 mJ/cm ² . An HC layer was formed by curing the coating layer by irradiating with ultraviolet rays. The coating thickness of the coating layer was adjusted so that the thickness of the HC layer was 7 μm. Thus, a protective film (1) having an HC layer on one side of the base film was obtained and wound up. The moisture permeability of the protective film (1) was 250 g/m ² ·day. The pencil hardness of the protective film (1) was 2H.

<Preparation of protective film (2)>
A protective film (2) was obtained in the same manner as the protective film (1), except that the thickness of the coating layer was adjusted so that the thickness of the HC layer was 5 μm. The moisture permeability of the protective film (2) was 350 g/m ² ·day. The pencil hardness of the protective film (2) was 3H.

<Preparation of protective film (3)>
A protective film (3) was obtained in the same manner as the protective film (1), except that the thickness of the coating layer was adjusted so that the thickness of the HC layer was 3 μm. The moisture permeability of the protective film (3) was 500 g/m ² ·day. The pencil hardness of the protective film (3) was 3H.

<Preparation of Retardation Laminate Containing Retardation Film and Other Retardation Layer>
A retardation film and other retardation layers were prepared according to paragraphs [0106] to [0109] of WO2018/207798. Specifically, an unstretched cycloolefin polymer film (manufactured by JSR Corporation, trade name “Arton film”) was uniaxially stretched to obtain a retardation film having a thickness of 24 μm. When the tensile modulus of the obtained retardation film was measured at a temperature of 23° C., it was 2742 MPa. The retardation film had an in-plane retardation value Re(550) of 110 nm at a wavelength of 550 nm, and a thickness direction retardation value Rth(550) of 55 nm at a wavelength of 550 nm.

Next, a retardation laminate was obtained by coating one side of the retardation film obtained above with a composition containing a rod-like liquid crystalline compound to form another retardation layer. The other retardation layer had an in-plane retardation value Re(550) of 0 nm at a wavelength of 550 nm, and a thickness direction retardation value Rth(550) of −100 nm at a wavelength of 550 nm.

<Preparation of polyvinyl alcohol-based adhesive (PVA-based adhesive)>
50 g of a modified PVA resin containing an acetoacetyl group (manufactured by Mitsubishi Chemical Corporation: Gohsenex Z-410) is dissolved in 950 g of pure water, heated at a temperature of 90 ° C. for 2 hours, cooled to room temperature, and polyvinyl alcohol solution. got Next, a polyvinyl alcohol solution, maleic acid, glyoxal, and pure water were blended so that each compound would have the following concentrations to prepare a PVA-based adhesive.
Polyvinyl alcohol concentration 3.0% by weight
Maleic acid concentration 0.01% by weight
Glyoxal concentration 0.15% by weight

<Preparation of adhesive layer A and adhesive layer B>
As the adhesive layer A, a commercially available sheet-like acrylic adhesive with a thickness of 5 μm (storage elastic modulus at a temperature of 23° C.: 0.06 MPa) was prepared.
As the adhesive layer B, a commercially available sheet-like acrylic adhesive with a thickness of 25 μm (storage elastic modulus at a temperature of 23° C. of 0.06 MPa) was prepared.

[Example 1]
The protective film (1) obtained above was immersed in a 1.5 mol/L NaOH aqueous solution (saponifying solution) kept at 55° C. for 2 minutes and then washed with water. The washed protective film (1) was immersed in a 0.05 mol/L sulfuric acid aqueous solution at 25° C. for 30 seconds and then passed under running water for 30 seconds to neutralize the protective film (1). After removing water from the protective film (1) with an air knife three times, it was dried by staying in a drying zone at a temperature of 70° C. for 15 seconds. As a result, a saponified protective film (1) was obtained in which the HC layer and the base film were subjected to saponification treatment (surface activation treatment).

A saponified protective film (1) (hereinafter sometimes referred to as “first protective film (1)”), a polarizing film, and a retardation laminate are combined with the PVA-based adhesive prepared above. A laminate (1) was obtained by laminating through In the laminate (1), the absorption axis of the polarizing film and the slow axis of the retardation film were parallel. In the laminate (1), the other retardation layer side of the retardation laminate faced the polarizing film, and the substrate film side of the first protective film (1) faced the polarizing film. The adhesive strength between the retardation laminate and the polarizing film and the adhesive strength between the polarizing film and the first protective film (1) were practically sufficient.

Next, on the first protective film (1) side of the laminate (1) obtained above, the saponified protective film ( 1) (hereinafter sometimes referred to as "second protective film (1)") was laminated. In the second protective film (1), the base film side was used as the bonding surface with the pressure-sensitive adhesive layer (A). Further, the phase difference laminate side of the laminate (1) is subjected to corona treatment, the surface of the adhesive layer B is subjected to corona treatment, and the corona-treated surface of the laminate (1) and the corona-treated surface of the adhesive layer (B) are treated. and laminated. Thus, a polarizing plate (1) was obtained. In the polarizing plate (1), both the first protective film (1) and the second protective film (1) are arranged on the same surface side of the polarizing film, and the first protective film (1) is the polarizing film , and the second protective film (1) was positioned relatively far from the polarizing film.

[Example 2]
A saponified protective film (2) which is saponified in place of the first protective film (1) and the second protective film (1) and subjected to the same saponification treatment as the saponification treatment performed on the protective film (1). A polarizing plate (2) was obtained in the same procedure as the polarizing plate (1) produced in Example 1, except that the polarizing plate (2) was used.

[Example 3]
A saponified protective film (3) which is saponified in place of the first protective film (1) and the second protective film (1) and is saponified in the same manner as the saponification of the protective film (1). A polarizing plate (3) was obtained in the same procedure as the polarizing plate (1) produced in Example 1, except that the polarizing plate (3) was used.

[Comparative Example 1]
Instead of the second protective film (1), a saponified base film (cellulose acylate film TD40, Fuji Film Co., Ltd. ), width 1,340 mm, film thickness 40 μm), a comparative polarizing plate (C1) was obtained in the same procedure as the polarizing plate (1) produced in Example 1.

[Comparative Example 2]
A laminate (1) produced in the same procedure as in Example 1 was obtained and used as a comparative polarizing plate (C2).

[Comparative Example 3]
Instead of the first protective film (1), saponified base film (cellulose acylate film TD40, FUJIFILM Corporation A comparative polarizing plate (C3) was obtained in the same manner as the polarizing plate (1) produced in Example 1, except that the polarizing plate (1) produced in Example 1 was used, except that a polarizing plate (1,340 mm in width and 40 μm in thickness) was used.

[Evaluation of crack generation]
For each of the polarizing plate obtained in the example and the comparative polarizing plate obtained in the comparative example, samples for evaluation were prepared according to the following procedure, and the generation of cracks was evaluated. A polarizing plate or a comparative polarizing plate is cut into a size of 200 mm × 200 mm, and pasted to an alkali-free glass having a thickness of 0.7 mm and a size of 300 mm × 300 mm via an adhesive layer B to prepare a sample for evaluation. did.

The prepared evaluation sample was held in a heating environment at a temperature of 105°C for 500 hours, and then cooled to a temperature of 23°C (normal temperature). Then, after holding for 30 days in a normal temperature and normal humidity environment with a temperature of 23° C. and a relative humidity of 55%, the retardation film of the polarizing plate or the comparative polarizing plate was observed to confirm the presence or absence of cracks. Furthermore, for the evaluation sample in which no cracks were observed at this point, the retardation film was observed 7 days later (37 days after the start of holding under the normal temperature and humidity environment) to determine whether cracks occurred. Checked for presence. Table 1 shows the results.

1 polarizing plate, 11 polarizing film, 11a first surface, 11b second surface, 12, 13 protective film, 21 retardation film, 31 to 33 bonding layer, 35 adhesive layer.

Claims

A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film;
a protective film in which a hard coat layer is provided on a base film;
A retardation film having a tensile modulus of elasticity of 3000 MPa or less at a temperature of 23 ° C.,
Two or more of the protective films are laminated on the first surface side of the polarizing film,
A polarizing plate, wherein the retardation film is laminated on a second surface side opposite to the first surface side of the polarizing film.
2. The moisture permeability of at least one of the two or more protective films laminated on the first surface side at a temperature of 40° C. and a relative humidity of 90% is 200 g/m 2 ·day or more. The polarizing plate described in .
Among the two or more protective films laminated on the first surface side, the protective film laminated most on the polarizing film side has a moisture permeability of 200 g/m 2 ·day or more at a temperature of 40°C and a relative humidity of 90%. The polarizing plate according to claim 1 or 2, wherein
The base film of at least one of the two or more protective films laminated on the first surface side is a cellulose resin film, according to any one of claims 1 to 3. Polarizer.
The polarizing plate according to any one of claims 1 to 4, wherein the retardation film is a cyclic olefin resin film.
6. The polarizing plate according to claim 1, wherein the retardation film has an in-plane retardation value of 80 nm or more at a wavelength of 550 nm.
The polarizing plate according to any one of claims 1 to 6, further comprising an adhesive layer on the side of the retardation film opposite to the polarizing film side.
A display device comprising the polarizing plate according to claim 7 and a display element,
The display device, wherein the polarizing plate is laminated on a display element via the pressure-sensitive adhesive layer.