JP2013200445A - Circularly polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing plate which is excellent in heat resistance and humidity resistance and is excellent in visibility when wearing polarizing sunglasses.SOLUTION: There is provided a method for manufacturing a polarizing plate, the method comprising the steps of: forming a polyvinyl alcohol-based resin layer 2 on at least one side of a base film 1 to obtain a laminate film 3; uniaxially stretching the laminate film 3 so that a resin layer 2 has a thickness of 10 μm or less to obtain a stretched film 4; forming a polarizer layer 5 by dying the stretched film 4 with a dichroic dye to obtain a polarizing laminate film 6; forming a moisture-proof layer 7, which has a moisture permeability of 200 g/m/24hrs or less and an in-plane retardation of 100 nm or more and in which an angle θ of the slow axis is 20 degrees or more and 70 degrees or less with respect to an absorption axis of the polarizer layer 5, on a surface opposite to the base film 1 of the polarizer layer 5 to obtain a multilayer film 8 in the polarizing laminate film 6; and peeling the base film 1 from the multilayer film 8.

Description

  The present invention relates to a circularly polarizing plate. Moreover, this invention relates to the circularly-polarizing plate with an adhesive layer which provided the adhesive layer in this circularly-polarizing plate, and an image display apparatus using the same.

  An image display device such as a liquid crystal display device or an organic EL display device may be provided with a circularly polarizing plate on the viewing side in order to prevent reflection of external light. Such a circularly polarizing plate has a polarizer layer and a phase difference layer such as a quarter-wave plate, and makes light incident on the image display device from the outside into circularly polarized light so that light is emitted outside the device. Therefore, the retardation layer is usually disposed so as to be inside the image display device.

  In recent years, the image display device has been reduced in size and weight, and the circular polarizing plate used in the image display device is also required to be reduced in size and weight. In addition, since the image display device may be used in a high temperature and high humidity environment, the circularly polarizing plate is also required to have heat resistance and moisture resistance.

  On the other hand, in an environment such as outdoors where the sunlight is strong, the image display device may be visually recognized in a state of wearing polarized sunglasses in order to eliminate the glare. Since the light emitted from the image display device is usually linearly polarized light, when the image display device is viewed with the polarized sunglasses on, the absorption axis of the polarized sunglasses and the polarization axis of the linearly polarized light from the image display device are Depending on the angle formed, there may be a problem in visibility.

  Under such circumstances, Patent Document 1 discloses that a quarter-wave plate is provided on one surface (image display unit side) of the thinned polarizer layer and is easily bonded to the other surface (viewing side). A circularly polarizing plate in which an agent layer, a protective layer, and a retardation layer are provided in this order is described.

Japanese Patent No. 4804589

  The circularly polarizing plate described in Patent Document 1 has a large number of layers as a whole, and is not always satisfactory in terms of heat resistance and humidity resistance under high temperature and high humidity.

  Therefore, an object of the present invention is to provide a circularly polarizing plate that is excellent in heat resistance and moisture resistance under high temperature and high humidity while suppressing the total number of layers and thickness and ensuring visibility when wearing polarized sunglasses. There is.

The present invention includes the following.
[1] A moisture-proof layer, a photocurable adhesive layer, a polarizer layer, and a retardation layer are laminated in this order,
Moisture permeability of the moisture-proof layer is not more than 200g ^/ m 2 ^/ 24hrs,
The in-plane retardation value of the moisture-proof layer is 100 nm or more,
The angle θ of the slow axis of the moisture-proof layer with respect to the absorption axis of the polarizer layer is 20 degrees or more and 70 degrees or less,
The polarizer layer is formed of a polyvinyl alcohol-based resin having a dichroic dye adsorbed and oriented,
The thickness of the said polarizer layer is a circularly-polarizing plate which is 10 micrometers or less.

[2] The circularly polarizing plate according to [1], wherein the polarizer layer and the retardation layer are laminated via an adhesive layer.

[3] The circularly polarizing plate according to [1] or [2], wherein a surface treatment is performed on a surface of the moisture-proof layer opposite to the photocurable adhesive layer.

[4] The circularly polarizing plate according to any one of [1] to [3];
The circularly-polarizing plate with an adhesive layer which has an adhesive layer provided in the surface on the opposite side to the polarizer layer in the said phase difference layer.

[5] An image display device comprising: the circularly polarizing plate with the pressure-sensitive adhesive layer according to [4]; and an image display unit bonded on the pressure-sensitive adhesive layer side of the circularly polarizing plate.

[6] A resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer on at least one surface of the base film,
Stretching process for obtaining a stretched film by uniaxially stretching the laminated film so that the thickness of the polyvinyl alcohol resin layer is 10 μm or less,
Dyeing process for obtaining a polarizing laminated film by dyeing the stretched film with a dichroic dye to form a polarizer layer,
In the polarizing laminate film, the surface opposite to the base film of the polarizer layer, a moisture permeability of not more than 200g ^/ m 2 / 24hrs, and the in-plane retardation is 100nm or more, the A moisture-proof layer forming step of obtaining a multilayer film by forming a moisture-proof layer having a slow axis angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer through a photocurable adhesive layer;
A peeling step of peeling the base film from the multilayer film to obtain a polarizing film with a moisture-proof layer, and
In the polarizing film with a moisture-proof layer, a retardation layer forming step of forming a retardation layer on the surface of the polarizer layer opposite to the moisture-proof layer,
The manufacturing method of the circularly-polarizing plate containing this.

  According to the present invention, it is possible to provide a circularly polarizing plate that is excellent in heat resistance and moisture resistance under high temperature and high humidity while suppressing the total number of layers and thickness and ensuring visibility when wearing polarized sunglasses. it can. Moreover, an adhesive layer can be provided on this circularly polarizing plate to form a circularly polarizing plate with an adhesive layer, and further bonded to an image display unit via the adhesive layer to form an image display device. Can do.

The conceptual diagram which shows an example of the cross section of the circularly-polarizing plate of this invention. The conceptual diagram which shows the relationship between the slow axis of a moisture-proof layer, and the absorption axis of a polarizer layer. The conceptual diagram which shows an example of the cross section of the circularly-polarizing plate of this invention. The figure which represented typically the cross section of the film obtained at each process of the manufacturing method of this invention. The conceptual diagram which shows an example of the cross section of the circularly-polarizing plate with an adhesive layer of this invention. The conceptual diagram which shows an example of the cross section of the circularly-polarizing plate with an adhesive layer of this invention. The conceptual diagram which shows an example of the cross section of the image display apparatus of this invention. The conceptual diagram which shows an example of the cross section of the image display apparatus of this invention.

  Hereinafter, the circularly polarizing plate of the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram showing a cross section of a circularly polarizing plate 20 which is an example of the present invention. The circularly polarizing plate 20 is a circularly polarizing plate in which the moisture-proof layer 1, the photocurable adhesive layer 2, the polarizer layer 3, and the retardation layer 5 are laminated in this order. Here, the pressure-sensitive adhesive layer 4 may be interposed between the polarizer layer 3 and the retardation layer 5. On the other hand, from the viewpoint of heat resistance and moisture resistance of the circularly polarizing plate, it is preferable that the moisture-proof layer 1, the photocurable adhesive layer 2, and the polarizer layer 3 are directly laminated.

<Polarizer layer 3>
The polarizer layer 3 is a layer of 10 μm or less formed from a polyvinyl alcohol-based resin having a dichroic dye adsorbed and oriented. The visibility corrected single transmittance (Ty) of the polarizer layer 3 is usually 40% or more, and preferably 41.5% or more. Moreover, the visibility correction | amendment polarization degree (Py) of the polarizer layer 3 is 97% or more normally, Preferably it is 99% or more. Since the polarizer layer 3 has the Ty and Py, when the circularly polarizing plate having the polarizer layer 3 is used in an image display device, an excellent contrast ratio can be exhibited.

  Specifically, the polarizer layer 3 is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin layer. As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The polarizer layer 3 is oriented by stretching, and the stretching ratio is preferably more than 5 times, more preferably more than 5 times and not more than 17 times.

  The thickness of the polarizer layer 3 is 10 μm or less, preferably 7 μm or less.

  Examples of the dichroic dye include iodine and organic dyes. Examples of organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. can be used. One kind of these dichroic substances may be used, or two or more kinds may be used in combination.

<Dampproof layer 1>
Moisture barrier 1, the moisture permeability is less than 200g ^/ m 2 ^/ 24hrs, retardation values in that plane is 100nm or more. Further, the angle θ of the slow axis of the moisture-proof layer 1 with respect to the absorption axis of the polarizer layer 3 is 20 degrees or more and 70 degrees or less. As described above, the circularly polarizing plate of the present invention has a low moisture permeability and a moisture-proof layer having a predetermined phase difference at a predetermined axial angle, so that the image display device having the circularly polarizing plate is visually recognized through polarized sunglasses. In addition, an effect of exhibiting excellent visibility and exhibiting excellent heat resistance and heat-and-moisture resistance is exhibited.

Moisture permeability of the moisture-proof layer 1, the heat resistance of the polarizing plate obtained from the viewpoint of moisture ^resistance, 2g / m 2 / 24hrs or more and less 150g ^/ m 2 ^/ 24hrs. Moreover, it is preferable that the phase difference of the moisture-proof layer 7 is 10,000 nm or less from the viewpoint of visibility when wearing polarized sunglasses.

  Here, the angle θ of the slow axis of the moisture-proof layer 1 with respect to the absorption axis of the polarizer layer 3 will be described with reference to FIG. 2A is a schematic view of the moisture-proof layer 1 and the polarizer layer 3 as seen from the cross-sectional direction thereof, and FIG. 2B shows the moisture-proof layer 1 and the polarizer layer 3 stacked together. It is the typical figure seen from the 1 side in the normal line direction. 2A and 2B, the slow axis of the moisture-proof layer 1 is denoted by 1a, and the absorption axis of the polarizer layer 3 is denoted by 3a. The angle θ of the slow axis 1a of the moisture-proof layer 1 with respect to the absorption axis 3a of the polarizer layer 3 means θ shown in FIG.

The moisture barrier 1, (1) a layer formed by the phase difference expression material of the liquid crystal materials capable of expressing the moisture permeability and the phase difference described above, (2) a moisture permeability of not more than 200 g / m 2 ^/ 24hrs, A retardation film having an in-plane retardation of 100 nm or more is formed by being bonded so that the slow axis thereof is an angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer 5. The layer (2) is preferably employed.

As a material for forming the moisture-proof layer 1 can be selected from a resin moisture permeability is less than 200g ^/ m 2 / 24hrs, for example, polyethylene terephthalate, polyethylene naphthalate, polyester resins and the like polybutylene terephthalate Examples include films, cyclic polyolefin resin films, polycarbonate resin films, (meth) acrylic resin films, polypropylene resin films, and the like.

  The polyester resin is a polymer having an ester bond and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the polyvalent carboxylic acid used, divalent dicarboxylic acid is mainly used, and examples thereof include isophthalic acid, terephthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. In addition, divalent diol is mainly used as the polyhydric alcohol used, and examples thereof include propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

  Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate, and the like. Can be mentioned. These blend resins and copolymers can also be suitably used.

  Examples of the cyclic polyolefin-based resin include appropriate commercial products such as Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (Nippon ZEON ( ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be suitably used. When such a cyclic polyolefin resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, pre-filmed cyclic polyolefins such as Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa (registered trademark) film (manufactured by Optes Co., Ltd.) A commercial product of a film made of a resin may be used.

  The cyclic polyolefin resin film may be uniaxially stretched or biaxially stretched. An arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film by stretching. Stretching is usually performed continuously while unwinding the film roll, and is stretched in the heating furnace in the roll traveling direction, the direction perpendicular to the traveling direction, or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin resin to the glass transition temperature + 100 ° C. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in one direction.

  Since the cyclic polyolefin resin film is generally inferior in surface activity, the surface to be bonded to the polarizing laminated film is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment. It is preferred to do so. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

  The thickness of the moisture-proof layer is preferably 90 μm or less, and more preferably 50 μm or less, from the viewpoint of thinning the circularly polarizing plate. On the other hand, it is preferable that it is 5 micrometers or more from viewpoints, such as mechanical strength in the process of obtaining a circularly-polarizing plate.

  The retardation film may have been previously surface-treated on the surface opposite to the surface to be bonded to the polarizer layer (not shown). Examples of the surface treatment include a treatment for forming a hard coat layer, an antistatic layer, an antifouling layer, an antireflection layer, and an antiglare layer. A surface treatment combining a plurality of these may be used. The method for forming these surface treatment layers on the surface of the retardation film is not particularly limited, and a known method can be used.

(Hard coat layer)
The hard coat layer has a function of increasing the surface hardness of the film and is provided for the purpose of preventing scratches on the surface. The hard coat layer preferably shows H or a value harder than that in the pencil hardness test specified in JIS K 5600-5-4. When this hard coat layer is formed, there is an advantage that scratches are hardly generated even when the surface is rubbed with a cloth or the like in order to remove the surface dirt in the manufacturing process or the final product. The material for forming such a hard coat layer is generally cured by heat or light. Examples thereof include organic hard coat materials such as organic silicone, melamine, epoxy, acrylic, and urethane acrylate, and inorganic hard coat materials such as silicon dioxide.

(Antistatic layer)
The antistatic layer is provided for the purpose of imparting conductivity to the surface of the film and suppressing the influence of static electricity. For forming the antistatic layer, for example, a method of applying a resin composition containing a conductive substance (antistatic agent) can be employed. For example, an antistatic hard coat layer can be formed by allowing an antistatic agent to coexist in the hard coat material used for forming the hard coat layer described above.

(Anti-fouling layer)
The antifouling layer is provided for imparting water repellency, oil repellency, sweat resistance, antifouling properties and the like to the surface of the film. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, and high molecular compounds thereof. As a method for forming the antifouling layer, a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, or the like typified by vapor deposition or sputtering can be used depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, preferably 3 to 35 nm.

(Antireflection layer)
The antireflection layer is a layer for preventing reflection of external light incident on the film, and is provided on the outermost layer (surface exposed to the outside) of the film. In this case, it may be formed directly on the film, or may be formed on the outermost surface of another layer such as a hard coat layer. The film provided with the antireflection layer preferably has a reflectance of 2% or less at an incident angle of 5 ° with respect to light having a wavelength of 430 to 700 nm, and particularly has a reflectance at the same incident angle with respect to light having a wavelength of 550 nm. It is preferable that it is 1% or less.

  The thickness of the antireflection layer can be about 0.01 to 1 μm, but a range of 0.02 to 0.5 μm is more preferable. The antireflection layer is composed of a low refractive index layer having a refractive index smaller than the refractive index of the layer on which it is provided, specifically a refractive index of 1.30 to 1.45, or a low refractive index of a thin film made of an inorganic compound. For example, a plurality of high-refractive-index layers and thin layers made of an inorganic compound may be alternately stacked.

  The material for forming the low refractive index layer is not particularly limited as long as it has a low refractive index. Examples thereof include a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in a resin, and a sol-gel material containing alkoxysilane. Such a low refractive index layer may be formed by applying a polymer that has been polymerized, or may be formed by applying the precursor in the state of a monomer or oligomer that is a precursor, followed by polymerization and curing. Moreover, it is preferable that each material contains the compound which has a fluorine atom in a molecule | numerator, in order to provide antifouling property.

(Anti-glare layer)
The antiglare layer is provided in order to reduce regular reflection of fluorescent lamps, sunlight, and the like by scattering the reflection of external light on the film at various angles. Thereby, an image of a fluorescent lamp or the like is hardly reflected, and the visibility of the display device is improved. The antiglare layer may be a method of dispersing fine particles in a photocurable resin, or a method of forming a fine uneven shape on the surface by an embossing method or the like.

  When fine particles such as those described above are used to form an antiglare layer, inorganic or organic fine particles are dispersed in each component constituting the photocurable resin composition, and then the resin composition is applied onto a film to produce light. Can be used to form a hard coat layer (antiglare layer) in which fine particles are dispersed in a transparent resin.

  On the other hand, when forming an antiglare layer having a fine surface irregularity shape by an embossing method, the mold shape is transferred to a resin layer formed on a film using a mold having a fine irregularity shape. That's fine. In the case of forming a fine surface uneven shape by an embossing method, the resin layer to which the uneven shape is transferred may or may not contain inorganic or organic fine particles. The uneven shape transfer by the embossing method is preferably a UV embossing method using an ultraviolet curable resin.

<Phase difference layer 5>
The phase difference layer 5 is a layer for exhibiting a function of preventing light from being emitted outside the apparatus by making light incident on the image display apparatus from the outside into circularly polarized light and, as a result, preventing reflection of external light. . Therefore, the retardation layer 5 is usually disposed so as to be inside the image display device. The retardation layer 5 is appropriately selected from a ½ wavelength plate, a ¼ wavelength plate, a ５ wavelength plate, a ６ wavelength plate, and the like depending on the use of the circularly polarizing plate having the layer. For example, when one retardation layer 5 is provided as shown in FIG. 1, a quarter wavelength plate is preferable as the retardation layer 5. In addition to the retardation layer 5 as shown in FIG. 3, when the second retardation layer 6 is provided, a half-wave plate is preferable as the retardation layer 5, and as the second retardation layer 6, 1 is used. A quarter wave plate is preferred. The configuration having two retardation layers as shown in FIG. 3 is preferable in that circularly polarized light can be created over a wide wavelength range of visible light.

  Examples of the retardation layer include a retardation film made of a triacetyl cellulose resin, a polycarbonate resin, or a cyclic polyolefin resin. Commercially available products corresponding to retardation films made of cyclic polyolefin resin include Arton (registered trademark) film (manufactured by JSR Corporation), Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), and Zeonore (registered trademark). ) Film (manufactured by Optes Co., Ltd.).

  As shown in FIGS. 1 and 3, the retardation layer 5 can be laminated via an adhesive layer (4 a). Moreover, when it has two phase difference layers, they can be laminated | stacked sequentially through an adhesive layer (4a, 4b). As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives can be used, and examples thereof include acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by a method in which the pressure-sensitive adhesive is applied to the surface of the film with a die coater or a gravure coater and dried. Moreover, it can also provide by the method of transcribe | transferring the sheet-like adhesive formed on the plastic film (it is called a separate film) to which the mold release process was given to the surface of a film. Although there is no restriction | limiting in particular also about the thickness of an adhesive layer, It is preferable to exist in the range of 2-40 micrometers.

<Photocurable adhesive layer 2>
The circularly polarizing plate 20 of the present invention is a circularly polarizing plate having a photocurable adhesive layer 2 between the moisture-proof layer 1 and the polarizer layer 3. Although any layer can be provided between the moisture-proof layer 1 and the photocurable adhesive layer 2 and / or between the photocurable adhesive layer 2 and the polarizer layer 3, the moisture-proof layer A configuration in which the layer 1, the photocurable adhesive layer 2, and the polarizer layer 3 are directly laminated in this order is preferable from the viewpoints of heat resistance and moisture resistance of the circularly polarizing plate.

  The photocurable adhesive constituting the photocurable adhesive layer 2 is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerization initiator, The thing containing a photoreactive resin, the thing containing a binder resin and a photoreactive crosslinking agent, etc. can be mentioned. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals by irradiation with active energy rays such as ultraviolet rays. As a photocurable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator are preferable.

<Method for producing circularly polarizing plate>
The manufacturing method of the circularly-polarizing plate of this invention is a resin layer formation process (S10) which obtains a laminated | multilayer film by forming a polyvinyl alcohol-type resin layer in at least one surface of a base film, The said laminated | multilayer film is made into polyvinyl alcohol-type resin. Stretching step (S20) to obtain a stretched film by uniaxially stretching so that the thickness of the layer is 10 μm or less, and dyeing the stretched film with a dichroic dye to form a polarizer layer, thereby obtaining a polarizing laminated film Step (S30), in the polarizing laminated film, a multilayer film is obtained by forming a moisture-proof layer on the surface of the polarizer layer opposite to the base film via a photocurable adhesive layer. Moisture-proof layer forming step (S40), peeling step (S50) for peeling the base film from the multilayer film to obtain a polarizing film with a moisture-proof layer, and with the moisture-proof layer In the optical film, wherein the said moisture barrier polarizer layer comprising the surface opposite the phase difference layer forming step of forming a retardation layer (S60). FIG. 4 is a diagram schematically showing a cross section of the film obtained by each step. Hereinafter, the production method of the present invention will be described in detail with reference to FIG.

[Resin Layer Forming Step (S10)]
In the resin layer forming step, a polyvinyl alcohol resin layer 8 is formed on at least one surface of the base film 7 to obtain a laminated film 9 (FIG. 4A).

(Base film)
As the resin used for the base film 7, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, stretchability and the like is used, and an appropriate resin can be selected according to Tg or Tm thereof. Specific examples of the thermoplastic resin include polyolefin resins such as chain polyolefin resins and cyclic polyolefin resins, polyester resins, (meth) acrylic resins, cellulose ester resins, polycarbonate resins, polyvinyl alcohol resins, Examples thereof include vinyl acetate resins, polyarylate resins, polystyrene resins, polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, and mixtures and copolymers thereof.

  The base film 7 can be a single layer or a multilayer composed of the resin described above.

  As the chain polyolefin-based resin, polyethylene, polypropylene and the like are preferable because they can be stably stretched at a high magnification. Moreover, an ethylene-polypropylene copolymer obtained by copolymerizing propylene with ethylene can also be suitably used. Copolymerization can be performed with other types of monomers, and examples of other types of monomers copolymerizable with propylene include ethylene and α-olefins. As the α-olefin, an α-olefin having 4 or more carbon atoms is preferable, and an α-olefin having 4 to 10 carbon atoms is more preferable. Specific examples of the α-olefin having 4 to 10 carbon atoms include linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene; 3-methyl Branched monoolefins such as -1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; vinylcyclohexane and the like. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. The content of the structural unit derived from the other monomer in the copolymer is determined by infrared (IR) spectrum according to the method described on page 616 of “Polymer Analysis Handbook” (1995, published by Kinokuniya). It can be obtained by measuring.

  Among the above, propylene-based resins constituting the propylene-based resin film include propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer, and propylene-ethylene-1-butene. Random copolymers are preferred.

  The stereoregularity of the propylene resin constituting the propylene resin film is preferably substantially isotactic or syndiotactic. A propylene-based resin film made of a propylene-based resin having substantially isotactic or syndiotactic stereoregularity has relatively good handleability and excellent mechanical strength in a high-temperature environment.

  As the cyclic polyolefin resin, a norbornene resin is preferably used. Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as cyclic polyolefin resins. As specific examples, Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Corporation), ZEONEX (ZEONEX) (Registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.) and the like.

  The polyester resin is a polymer having an ester bond and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the polyvalent carboxylic acid used, divalent dicarboxylic acids are mainly used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. In addition, divalent diol is mainly used as the polyhydric alcohol used, and examples thereof include propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol and the like.

  A typical example of the polyester resin is polyethylene terephthalate which is a copolymer of terephthalic acid and ethylene glycol. Polyethylene terephthalate is a crystalline resin, but the one in a state before crystallization treatment is more easily subjected to treatment such as stretching. If necessary, it can be crystallized during stretching or by heat treatment after stretching. In addition, a copolymerized polyester whose crystallinity has been lowered (or made amorphous) by further copolymerizing another monomer with the polyethylene terephthalate skeleton is also preferably used. As examples of such resins, for example, those obtained by copolymerization of cyclohexanedimethanol, isophthalic acid or the like are preferably used. These resins are also excellent in stretchability and can be suitably used.

  Specific resins other than polyethylene terephthalate and copolymers thereof include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate. Phthalate, and the like. These blend resins and copolymers can also be suitably used.

  Any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, C1-6 alkyl poly (meth) acrylates, such as poly (meth) acrylate methyl, are mentioned. More preferably, as the (meth) acrylic resin, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those obtained by modifying a part of the hydroxyl group with other types of substituents are also included. Among these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ (Fuji Film ( Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.), and the like.

  The polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, and flame retardancy. Moreover, since it has high transparency, it is suitably used in optical applications. In optical applications, resins called modified polycarbonates in which the polymer skeleton is modified in order to lower the photoelastic coefficient, copolymerized polycarbonates with improved wavelength dependency, and the like are commercially available and can be suitably used. Such polycarbonate resins are widely commercially available. For example, Panlite (registered trademark) (Teijin Chemicals Ltd.), Iupilon (registered trademark) (Mitsubishi Engineering Plastics), SD Polyca (registered trademark) (Sumitomo) Dow Co., Ltd.), Caliber (registered trademark) (Dow Chemical Co., Ltd.) and the like.

  Arbitrary appropriate additives may be added to the base film 7 in addition to the thermoplastic resin. Examples of such additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. . The content of the thermoplastic resin exemplified above in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97%. % By weight. This is because, if the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

  Although the thickness of the base film 7 can be determined as appropriate, it is generally preferably 1 to 500 μm, more preferably 1 to 300 μm, and even more preferably 5 to 200 μm from the viewpoint of workability such as strength and handleability. As for the thickness of a base film, 5-150 micrometers is the most preferable.

  In order to improve the adhesiveness with the resin layer, the base film 7 may be subjected to corona treatment, plasma treatment, flame treatment, or the like on at least the surface on which the resin layer is formed. Moreover, in order to improve adhesiveness, you may form thin layers, such as a primer layer and an adhesive bond layer, on the surface of the side in which the resin layer of a base film is formed. In addition, a base film here means what does not contain an adhesive bond layer, a corona treatment layer, etc.

(Polyvinyl alcohol resin layer)
The polyvinyl alcohol-based resin layer 8 is typically formed by applying a polyvinyl alcohol-based resin solution obtained by dissolving polyvinyl alcohol-based resin powder in a highly soluble solvent such as water onto one surface of a base film. Formed by evaporating and drying the solvent. By forming the resin layer in this way, it can be formed thin. As a method of applying a polyvinyl alcohol resin solution to a base film, a wire bar coating method, a reverse coating, a roll coating method such as gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, a screen coating method. A method, a fountain coating method, a dipping method, a spray method, and the like can be appropriately selected from known methods and employed. A drying temperature is 50-200 degreeC, for example, Preferably it is 60-150 degreeC. The drying time is, for example, 2 to 20 minutes.

  The thickness of the resin layer 8 to be formed is preferably more than 3 μm and not more than 30 μm, and more preferably 5 to 20 μm. If it is 3 μm or less, the film becomes too thin after stretching and the dyeability is remarkably deteriorated. If it exceeds 30 μm, the thickness of the finally obtained polarizer layer may exceed 10 μm.

  In order to improve the adhesion between the base film 7 and the polyvinyl alcohol resin layer 8, a primer layer may be provided between the base film 7 and the resin layer 8. The primer layer is preferably formed from a composition containing a crosslinking agent or the like in a polyvinyl alcohol resin from the viewpoint of adhesion.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The polyvinyl alcohol resin is preferably a completely saponified product. The range of the saponification degree is preferably 80.0 mol% to 100.0 mol%, more preferably 90.0 mol% to 99.5 mol%, more preferably 94.0 mol%. Most preferred is a range of from% to 99.0 mol%. If the degree of saponification is less than 80.0 mol%, the water and moisture resistance of the resulting polarizing plate may be lowered. On the other hand, when the degree of saponification exceeds 99.5 mol%, the dyeing speed is slow, and a polarizing laminate film having sufficient polarizing performance may not be obtained.

The saponification degree as used herein is a unit ratio (mol%) representing the ratio of the acetate group contained in the polyvinyl acetate resin, which is a raw material for the polyvinyl alcohol resin, to a hydroxyl group by the saponification step. Is a numerical value defined by the following formula. It can be determined by the method defined in JIS K 6726 (1994).
Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100
The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetate groups that inhibit crystallization.

  The polyvinyl alcohol-based resin may be a modified polyvinyl alcohol partially modified. For example, polyvinyl alcohol resins modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, alkyl esters of unsaturated carboxylic acids, acrylamide, and the like can be used. The proportion of modification is preferably less than 30 mol%, and more preferably less than 10%. When the modification exceeds 30 mol%, it becomes difficult to adsorb the dichroic dye, and the polarization performance may be lowered.

  The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but is preferably 100 to 10,000, more preferably 1500 to 8000, and most preferably 2000 to 5000. The average degree of polymerization here is also a numerical value determined by a method defined by JIS K 6726 (1994).

  Examples of the polyvinyl alcohol resin having such characteristics include PVA124 (degree of saponification: 98.0 to 99.0 mol%) and PVA117 (degree of saponification: 98.0 to 99.0) manufactured by Kuraray Co., Ltd. Mol%), PVA624 (degree of saponification: 95.0-96.0 mol%) and PVA617 (degree of saponification: 94.5-95.5 mol%); for example, AH- manufactured by Nippon Synthetic Chemical Industry Co., Ltd. 26 (degree of saponification: 97.0-98.8 mol%), AH-22 (degree of saponification: 97.5-98.5 mol%), NH-18 (degree of saponification: 98.0-99. 0 mol%), and N-300 (degree of saponification: 98.0 to 99.0 mol%); for example, JC-33 (degree of saponification: 99.0 mol% or more) of Nippon Vinegar Pival Co., Ltd. , JM-33 (degree of saponification: 93.5 to 95.5 mol%), JM-26 Saponification degree: 95.5-97.5 mol%), JP-45 (saponification degree: 86.5-89.5 mol%), JF-17 (degree of saponification: 98.0-99.0 mol) %), JF-17L (degree of saponification: 98.0 to 99.0 mol%), JF-20 (degree of saponification: 98.0 to 99.0 mol%), and the like. Can be used.

[Stretching step (S20)]
In the stretching step, the laminated film 9 is uniaxially stretched so that the thickness of the polyvinyl alcohol-based resin layer is 10 μm or less to obtain a stretched film 10 (FIG. 4B). The draw ratio of uniaxial stretching is preferably more than 5 times and not more than 17 times, and more preferably more than 5 times and not more than 8 times. When the draw ratio is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer may not be sufficiently high. On the other hand, if the draw ratio exceeds 17 times, the laminated film 9 is likely to break during stretching, and at the same time, the thickness of the stretched film 10 becomes unnecessarily thin, and the workability and handling properties in the subsequent process may be reduced. is there. The stretching process in the stretching step (S20) is not limited to one-stage stretching, and can be performed in multiple stages. In this case, the second and subsequent stretching steps may be performed in the stretching step (S20), but may be performed simultaneously with the dyeing process and the crosslinking process in the dyeing process (S30). Thus, when extending | stretching by multistage, extending | stretching process is performed so that it may become a draw ratio exceeding 5 times combining all the stages of extending | stretching process.

  In the stretching step (S20) in the present embodiment, a longitudinal stretching process performed in the longitudinal direction of the laminated film 9, a lateral stretching process stretching in the width direction, and the like can be performed. Examples of the longitudinal stretching method include an inter-roll stretching method and a compression stretching method, and examples of the transverse stretching method include a tenter method.

  In addition, as the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but the use of the dry stretching method is preferable in that the temperature at which the laminated film 9 is stretched can be selected from a wide range. .

  The stretching temperature is set to be equal to or higher than the temperature at which the polyvinyl alcohol-based resin layer 8 and the entire base film 7 can be stretched, and preferably the phase transition temperature of the base film 7 is −30 ° C. to + 30 ° C. More preferably, it is the range of −25 ° C. to + 30 ° C. of the phase transition temperature of the base film 7. If the stretching temperature is lower than the phase transition temperature of −30 ° C., it is difficult to achieve a high-magnification stretching of more than 5 times. When the stretching temperature exceeds + 30 ° C. of the phase transition temperature, the fluidity of the base film tends to be too high and stretching tends to be difficult. Since it is easier to achieve a high draw ratio of more than 5 times, the drawing temperature is within the above range, and more preferably 120 ° C. or higher. The temperature adjustment of the stretching process is usually performed by adjusting the temperature of the heating furnace.

[Dyeing step (S30)]
In the dyeing step, the stretched film 10 is dyed with a dichroic dye to form the polarizer layer 3 to obtain the polarizing laminated film 11 (FIG. 4C). Examples of the dichroic dye include iodine and organic dyes as described above.

  A dyeing process is performed by immersing the stretched film 10 whole in the solution (dyeing solution) containing the said dichroic dye, for example. As the staining solution, a solution in which the above dichroic dye is dissolved in a solvent can be used. As a solvent for the dyeing solution, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight, and particularly preferably 0.025 to 5% by weight.

  When iodine is used as the dichroic dye, it is preferable to further add an iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.01 to 20% by weight in the dyeing solution. Of the iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80 by weight. , Particularly preferably in the range of 1: 7 to 1:70.

  The immersion time of the stretched film 10 in the dyeing solution is not particularly limited, but it is usually preferably in the range of 15 seconds to 15 minutes, and more preferably 30 seconds to 3 minutes. Moreover, it is preferable that it is in the range of 10-60 degreeC, and, as for the temperature of a dyeing | staining solution, it is more preferable that it exists in the range of 20-40 degreeC.

  Although the dyeing treatment can be performed before or simultaneously with the stretching step, the unstretched film is subjected to the stretching step so that the dichroic dye adsorbed on the polyvinyl alcohol-based resin can be favorably oriented. It is preferable to carry out after. At this time, it may be simply dyed what has been previously stretched at a target magnification, or may be a method in which a stretch previously stretched at a low magnification is re-stretched during dyeing to reach the target magnification in total. good. Further, when the stretching is performed during the subsequent crosslinking treatment, the stretching can be limited to a low magnification. In this case, adjustment may be made in a timely manner so as to reach the desired magnification after the crosslinking treatment.

  In the dyeing process, a crosslinking treatment can be performed after dyeing. The crosslinking treatment can be performed, for example, by immersing the stretched film in a solution containing a crosslinking agent (crosslinking solution). Conventionally known substances can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination.

  As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. Although the density | concentration of the crosslinking agent in a crosslinking solution is not limited to this, It is preferable to exist in the range of 1-20 weight%, and it is more preferable that it is 6-15 weight%.

  Iodide may be added to the crosslinking solution. By adding iodide, the in-plane polarization characteristics of the resin layer can be made more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Is mentioned. The iodide content is 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

  The immersion time of the stretched film in the crosslinking solution is usually preferably from 15 seconds to 20 minutes, and more preferably from 30 seconds to 15 minutes. Moreover, it is preferable that the temperature of a crosslinking solution exists in the range of 10-90 degreeC.

  In addition, a crosslinking process can also be performed simultaneously with a dyeing | staining process by mix | blending a crosslinking agent in a dyeing | staining solution. Moreover, what was previously extended | stretched by target magnification may be only bridge | crosslinked, and you may perform a bridge | crosslinking process and extending | stretching simultaneously. A stretched film that has been stretched at a low magnification in the stretching step in advance may be stretched again during the cross-linking treatment to reach the target magnification in total.

  Finally, it is preferable to perform a washing process and a drying process. As the cleaning process, a water cleaning process can be performed. The water washing treatment can usually be performed by immersing the stretched film in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 3 to 50 ° C, preferably 4 to 20 ° C. The immersion time is usually 2 to 300 seconds, preferably 3 to 240 seconds.

  The washing treatment may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution appropriately mixed with a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, propanol or the like can also be used.

  It is preferable to perform a drying process after the cleaning process. Any appropriate method (for example, natural drying, blow drying, heat drying) can be adopted as the drying treatment. For example, the drying temperature in the case of heat drying is usually 20 to 95 ° C., and the drying time is usually about 1 to 15 minutes. Through the above dyeing step (S30), the resin layer has a function as a polarizer. In this specification, the resin layer which has a function as a polarizer is called a polarizer layer, and the laminated body provided with the polarizer layer on the base film is called a polarizing laminated film.

[Moisture-proof layer forming step (S40)]
The moisture barrier formation step, in the polarizing laminate film 11, the on the opposite side to the substrate film 7 of the polarizer layer 3, the moisture permeability is less 200g ^/ m 2 / 24hrs, in-plane retardation A moisture barrier layer 1 having a slow axis angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer 3 is formed through the photocurable adhesive layer 2. Thus, the multilayer film 12 is obtained (FIG. 4D).

As a method for forming the moisture-proof layer 1, (1) a retardation-expressing substance such as a liquid crystal material capable of exhibiting the above-described moisture permeability and retardation on the surface of the polarizer layer 3 opposite to the base film 7. the formed by coating so that the predetermined slow axis direction methods, (2) the polarization in the surface opposite to the substrate film 7 photons layer 3, moisture permeability 200 g / m 2 ^/ 24hrs The retardation film having an in-plane retardation of 100 nm or more is bonded so that the slow axis thereof is an angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer 3. Although the method etc. are mentioned, the method of said (2) is employ | adopted preferably.

  As a retardation film, the film to which the retardation was normally provided by the extending | stretching process is mentioned. The direction of the slow axis of the retardation film is determined by the material of the retardation film and the stretching direction. For example, in the case of a film that has been longitudinally uniaxially stretched or laterally uniaxially stretched, it has a slow axis parallel or perpendicular to the longitudinal direction of the film, depending on the material of the film. When used as such a retardation film, after the film is cut, it is bonded so that its slow axis is in the direction of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer. When a film uniaxially stretched in an oblique direction so that the slow axis is 20 degrees or more and 70 degrees or less with respect to the longitudinal direction of the film is used as the retardation film, the retardation film is used in the longitudinal direction. It can be bonded in a so-called roll-to-roll format with a polarizing laminated film having an absorption axis in a parallel direction. The latter case is preferable from the viewpoint of production efficiency. The method for achieving the tilted slow axis is not particularly limited, and may be oblique stretching or transverse stretching. In the case of transverse stretching, since the slow axis is inclined except for the central part by intentionally strengthening the bow shape in the width direction, this part can also be suitably used as a retardation film.

  As a method of forming the moisture-proof layer 1 through the photocurable adhesive layer 2 on the surface of the base film 7, for example, the retardation film is bonded through a photocurable adhesive as described later. Thereafter, a photocuring method and the like can be mentioned.

  As a method of laminating a film with a photocurable adhesive, a conventionally known method can be used. For example, casting method, Mayer bar coating method, gravure coating method, comma coater method, doctor plate method, die coating method Examples of the method include applying an adhesive to the adhesive surface of the film by a dip coating method, a spraying method, and the like, and superimposing two films. The casting method is a method in which two films as an object to be coated are moved in a substantially vertical direction, generally in a horizontal direction, or in an oblique direction between the two, and an adhesive is allowed to flow down and spread on the surface. is there.

  After the adhesive is applied to the surface of the film, it is bonded by sandwiching the film with a nip roll or the like. Moreover, the method of pressing this laminated body with a roll etc. and spreading it uniformly can also be used suitably. In this case, a metal, rubber, or the like can be used as the material of the roll. Furthermore, a method in which this laminate is passed between rolls and pressed to spread is preferably employed. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after being bonded using the nip roll or the like before drying or curing is preferably 5 μm or less and 0.01 μm or more.

  In order to improve adhesiveness, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment may be appropriately performed on the adhesion surface of the film. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  When a photocurable resin is used as an adhesive, the photocurable adhesive is cured by irradiating active energy rays after laminating the films. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW / it is preferable that the cm ^2. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, the epoxy is generated by the heat radiated from the light source and the heat generated when the photo-curable adhesive is cured. There is little risk of yellowing of the resin or deterioration of the polarizing film. The light irradiation time to the photocurable adhesive is not particularly limited and is applied according to the photocurable adhesive to be cured, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. Is preferably set to be 10 to 10,000 mJ / cm ² . When the cumulative amount of light to the photocurable adhesive is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and at 10,000 mJ / cm ² or less. In some cases, irradiation time does not become too long and good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 μm, preferably 0.01 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1 μm or less.

  When curing a photocurable adhesive of a film containing a polarizer layer or moisture-proof layer by irradiation with active energy rays, various polarizing plate properties such as the degree of polarization, transmittance and hue of the polarizer layer, and transparency of the moisture-proof layer, etc. It is preferable to perform the curing under conditions where the function does not decrease.

[Peeling step (S50)]
At a peeling process, the said base film 7 is peeled from the multilayer film 12, and the polarizing film 13 with a moisture-proof layer is obtained (FIG.4 (E)). The peeling method of the base film 7 is not specifically limited, You may peel as it is, and after winding up once in roll shape, you may peel by providing a peeling process separately.

[Phase difference layer forming step (S60)]
In the retardation layer forming step, the retardation layer 5 is formed on the surface of the polarizer layer 3 opposite to the moisture-proof layer 1 in the polarizing film 13 with the moisture-proof layer (FIG. 4F). Here, when forming the retardation layer 5, it is preferable to form via the adhesive layer (4a) mentioned above. Moreover, when forming the 2nd phase difference layer 6 (refer FIG. 3) in addition to the phase difference layer 5, it is preferable to laminate | stack through an adhesive layer (4b) further.

<Circularly polarizing plate, circularly polarizing plate with adhesive layer, image display device>
The circularly polarizing plate 20 can be obtained through the steps S10 to S60 described above. Furthermore, as shown in FIG. 5, the pressure-sensitive adhesive layer 14 is provided on the surface of the retardation layer 5 opposite to the polarizer layer 3, whereby the polarizing plate 30 with the pressure-sensitive adhesive layer can be obtained. Moreover, as shown in FIG. 6, when providing the 2nd phase difference layer 6, the adhesive layer 14 is provided in the surface on the opposite side to the polarizer layer 3 of the phase difference layer 6, and an adhesive layer is attached. A circularly polarizing plate 30 can be obtained. The circularly polarizing plate 30 with the pressure-sensitive adhesive layer can be bonded to the image display unit 15 on the pressure-sensitive adhesive layer 14 side to form an image display device 40 as shown in FIGS.

  As an adhesive used for the circularly polarizing plate 30 with an adhesive layer, an acrylic resin, a styrene resin, a silicone resin, or the like is used as a base polymer, and a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound is used as the base polymer. The composition etc. which added are mentioned. Furthermore, it can also be set as the adhesive layer which contains microparticles | fine-particles in this base polymer and shows light-scattering property.

  The thickness of the pressure-sensitive adhesive layer 14 is preferably 1 to 40 μm, but it is preferably applied thinly, and more preferably 3 to 25 μm, as long as the workability and durability characteristics are not impaired. When it is 3 to 25 μm, it has good processability and is also suitable for suppressing the dimensional change of the polarizing film. When the pressure-sensitive adhesive layer 14 is less than 1 μm, the adhesiveness is lowered, and when it exceeds 40 μm, problems such as the pressure-sensitive adhesive protruding easily occur.

  The method for forming the pressure-sensitive adhesive layer 14 on the retardation layer is not particularly limited, and a solution containing each component including the above-described base polymer is applied on the retardation layer and dried. After the pressure-sensitive adhesive layer 14 is formed, it may be bonded to a separator or another type of film, or after the pressure-sensitive adhesive layer is formed on the separator, it may be bonded to the surface of the polarizer layer and laminated. Further, when the pressure-sensitive adhesive layer is formed on the surface of the polarizer layer, an adhesion treatment such as a corona treatment may be performed on the surface of the polarizer layer, or one or both of the pressure-sensitive adhesive layers as necessary.

  Examples of the image display unit 15 include a liquid crystal panel including a liquid crystal cell between glass substrates, an organic EL element, and the like. As the liquid crystal cell, those of various known drive methods can be used.

  Moreover, in the circularly-polarizing plate 20, another optical layer can be provided on the surface of the moisture-proof layer 1 opposite to the polarizer layer 3 as necessary. Examples of the other optical layers herein include a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a film with an antiglare function having an uneven surface, and a surface. Examples thereof include a film with an antireflection function, a reflection film having a reflection function on the surface, a transflective film having both a reflection function and a transmission function, and a viewing angle compensation film.

  Commercially available products corresponding to reflective polarizing films that transmit certain types of polarized light and reflect polarized light that exhibits the opposite properties include DBEF (available from 3M, Sumitomo 3M Co., Ltd.), APF (Available from 3M, available from Sumitomo 3M Limited). Examples of the viewing angle compensation film include an optical compensation film coated with a liquid crystal compound on the surface of the substrate and oriented, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface and oriented are WV film (Fuji Film Co., Ltd.), NH film (Shin Nippon Oil Co., Ltd.), NR Examples include films (manufactured by Nippon Oil Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resins include Arton (registered trademark) film (manufactured by JSR Corporation), Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), Zeonor ( Registered trademark) film (manufactured by Optes Co., Ltd.).

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these examples.

[Example 1]
(Base film)
An unstretched polypropylene (PP) film (melting point: 163 ° C.) having a thickness of 110 μm was used as the base film.

(Primer layer formation process)
Polyvinyl alcohol powder (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, saponification degree 99.5 mol%, trade name: Z-200) is dissolved in 95 ° C. hot water to give an aqueous solution having a concentration of 3% by weight. Prepared. The resulting aqueous solution was mixed with 5 parts by weight of a crosslinking agent (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirez (registered trademark) Resin 650) with respect to 6 parts by weight of polyvinyl alcohol powder. The obtained mixed aqueous solution was coated on a substrate film subjected to corona treatment using a micro gravure coater and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

(Polyvinyl alcohol-based resin layer forming step)
Polyvinyl alcohol powder having a concentration of 8% by weight by dissolving polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree 98.0-99.0 mol%, trade name: PVA124) in hot water at 95 ° C. An aqueous solution was prepared. The obtained aqueous solution was applied onto the primer layer using a lip coater and dried at 80 ° C. for 20 minutes to prepare a three-layered film including a base film, a primer layer, and a polyvinyl alcohol resin layer.

(Stretching process)
The laminated film was subjected to 5.8-fold free end uniaxial stretching at 160 ° C. using a tenter device to obtain a stretched film. The thickness of the stretched polyvinyl alcohol resin layer was 5.0 μm.

(Dyeing process)
The stretched film was dyed by immersing it in a dyeing solution that is a mixed aqueous solution of iodine and potassium iodide at 26 ° C. for 90 seconds, and then the excess iodine solution was washed away with 10 ° C. pure water. Next, it was immersed in a crosslinking solution, which is a mixed aqueous solution of boric acid and potassium iodide at 76 ° C. for 300 seconds. Thereafter, it was washed with pure water at 10 ° C. for 10 seconds, and finally dried at 80 ° C. for 200 seconds. The polarizer layer was formed from the resin layer by the above process, and the light-polarizing laminated film was obtained. The blending ratio of each solution is as follows.

<Dyeing solution>
Water: 100 parts by weight Iodine: 0.35 parts by weight Potassium iodide: 10 parts by weight <Crosslinking solution>
Water: 100 parts by weight Boric acid: 9.5 parts by weight Potassium iodide: 5 parts by weight

(Dampproof layer forming process)
In the above polarizing laminate film, a photocurable adhesive (Adekaoptomer KR-25T) is applied to the surface of the polarizer layer opposite to the base film, and then polyethylene terephthalate is used as a moisture-proof layer on the coated surface. film (moisture permeability ^33g / m 2 / 24hrs, thickness 25 [mu] m) and stuck to its slow axis is 45 degree angle with respect to the absorption axis of the polarizer layer, moisture barrier layer, an adhesive layer, A multilayer film consisting of 5 layers of a polarizer layer, a primer layer and a substrate film was obtained. The base film was peeled from the obtained multilayer film to obtain a polarizing plate comprising 4 layers of a moisture-proof layer, an adhesive layer, a polarizer layer, and a primer layer.

[Example 2]
Polyethylene terephthalate film as a moisture barrier (moisture permeability 140g ^/ m 2 ^/ 24hrs, thickness 5 [mu] m) except using the obtain a polarizing plate in the same manner as in Example 1.

[Example 3]
Consisting cycloolefin polymer as a moisture barrier film (moisture permeability 110g ^/ m 2 ^/ 24hrs, thickness 20 [mu] m) except using the obtain a polarizing plate in the same manner as in Example 1.

[Comparative Example 1]
Triacetyl cellulose film as a moisture barrier (moisture permeability 827g ^/ m 2 ^/ 24hrs, thickness 42 .mu.m) except using the obtain a polarizing plate in the same manner as in Example 1.

[Comparative Example 2]
The resulting triacetyl cellulose film (moisture permeability 827g ^/ m 2 / 24hrs, thickness 42 .mu.m) as moisture barrier point with, and, except for using the water-based adhesive as an adhesive polarizing plate in the same manner as in Example 1 It was. As an aqueous adhesive, polyvinyl alcohol powder (“KL-318” manufactured by Kuraray Co., Ltd., average polymerization degree 1800) is dissolved in hot water at 95 ° C. to prepare an aqueous polyvinyl alcohol solution having a concentration of 3% by weight. The aqueous solution was mixed with 1 part by weight of a crosslinking agent (“SUMIREZ RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) with respect to 2 parts by weight of polyvinyl alcohol powder to obtain an adhesive solution.

(Measurement of polarization performance)
The optical characteristics of the polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured with a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, V7100). MD transmittance and TD transmittance are obtained in a wavelength range of 380 nm to 780 nm, and single transmittance and polarization degree at each wavelength are calculated based on the following formulas (1) and (2). Further, according to JIS Z 8701 Visibility correction was performed with the field of view twice (C light source), and the visibility correction single transmittance (Ty) and the visibility correction polarization degree (Py) were obtained. In addition, the measurement of the polarizing plate was set in the apparatus so that the moisture-proof layer side was the detector side and light was incident from the primer layer side.

  In the above, “MD transmittance” is the transmittance when the direction of polarized light emitted from the Glan-Thompson prism is parallel to the transmission axis of the polarizing plate sample. In the formulas (1) and (2), “MD” ". The “TD transmittance” is the transmittance when the direction of polarized light emitted from the Glan-Thompson prism and the polarizing plate sample are orthogonal to the transmission axis. In the formulas (1) and (2), “TD”. It expresses.

Single transmittance (%) = (MD + TD) / 2 (1)
Degree of polarization (%) = {(MD−TD) / (MD + TD)} × 100 (2)

(Heat and humidity resistance test)
The polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were placed in an environment of 60 ° C. and 90% RH for 750 hours, and Py and Ty were determined for the subsequent polarizing plates. The evaluation results are shown in Table 1. In Table 1, Ty (%) at the start and Py (%) at the start mean Ty (%) and Py (%) at the start of the test, and Py (%) at the end indicates Py at the end of the test. ΔPy (%) means a difference obtained by subtracting the start Py (%) from the end Py (%).

[Example 4]
The polyethylene terephthalate film is bonded to the polarizing laminate film so that the slow axis of the polyethylene terephthalate film as the moisture-proof layer is every 10 degrees from 0 to 90 degrees with respect to the absorption axis of the polarizer layer. Each of the obtained polarizing plates was evaluated for visibility when wearing sunglasses. Those with good visibility were marked with “◯”, and those with poor visibility were marked with “x”. The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 Moisture-proof layer 2 Photocurable adhesive layer 3 Polarizer layer 4a, 4b, 14 Adhesive layers 5, 6 Retardation layer 7 Base film 8 Polyvinyl alcohol-type resin layer 9 Laminated film 10 Stretched film 11 Polarized laminated film 12 Polarizing film with moisture-proof layer 13 Multi-layer film 15 Image display unit 20 Circular polarizing plate 30 Circular polarizing plate with adhesive layer 40 Image display device

Claims (6)

A moisture-proof layer, a photocurable adhesive layer, a polarizer layer and a retardation layer are laminated in this order,
Moisture permeability of the moisture-proof layer is not more than 200g ^/ m 2 ^/ 24hrs,
The in-plane retardation value of the moisture-proof layer is 100 nm or more,
The angle θ of the slow axis of the moisture-proof layer with respect to the absorption axis of the polarizer layer is 20 degrees or more and 70 degrees or less,
The polarizer layer is formed of a polyvinyl alcohol-based resin having a dichroic dye adsorbed and oriented,
The thickness of the said polarizer layer is a circularly-polarizing plate which is 10 micrometers or less.   The circularly polarizing plate according to claim 1, wherein the polarizer layer and the retardation layer are laminated via an adhesive layer.   The circularly-polarizing plate of Claim 1 or 2 by which surface treatment is given to the surface on the opposite side to the photocurable adhesive bond layer in the said moisture-proof layer. The circularly polarizing plate according to any one of claims 1 to 3,
The circularly-polarizing plate with an adhesive layer which has an adhesive layer provided in the surface on the opposite side to the polarizer layer in the said phase difference layer.   The image display apparatus which has the circularly-polarizing plate with an adhesive layer of Claim 4, and the image display unit bonded by the adhesive layer side of this circularly-polarizing plate. A resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer on at least one surface of the base film,
Stretching process for obtaining a stretched film by uniaxially stretching the laminated film so that the thickness of the polyvinyl alcohol resin layer is 10 μm or less,
Dyeing process for obtaining a polarizing laminated film by dyeing the stretched film with a dichroic dye to form a polarizer layer,
In the polarizing laminate film, the surface opposite to the base film of the polarizer layer, a moisture permeability of not more than 200g ^/ m 2 / 24hrs, and the in-plane retardation is 100nm or more, the A moisture-proof layer forming step of obtaining a multilayer film by forming a moisture-proof layer having a slow axis angle θ of 20 degrees or more and 70 degrees or less with respect to the absorption axis of the polarizer layer through a photocurable adhesive layer;
A peeling step of peeling the base film from the multilayer film to obtain a polarizing film with a moisture-proof layer, and
In the polarizing film with a moisture-proof layer, a retardation layer forming step of forming a retardation layer on the surface of the polarizer layer opposite to the moisture-proof layer,
The manufacturing method of the circularly-polarizing plate containing this.

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