JP6075826B2 - Polarizing plate with retardation layer - Google Patents

Description

  The present invention relates to a polarizing plate with a retardation layer. More specifically, the present invention relates to a retardation layer-attached polarizing plate having a patterned retardation layer.

  Conventionally, a lot of researches have been made and put into practical use regarding technologies related to stereoscopic (three-dimensional) image display. The basic principle of stereoscopic display is by providing different images to the left and right eyes of the observer. As a technique related to stereoscopic image display, typically, a spectacle method in which an observer wears special spectacles or the like, and a naked eye method in which spectacles or the like are not worn are cited. In the eyeglass system, there are a time division system that alternately outputs and outputs a left-eye image and a right-eye image, and a space-division system that outputs left and right images having different polarization directions for each line of a liquid crystal cell. In the space division method, in order to output left and right images having different polarization directions for each line of the liquid crystal cell, it is necessary to develop a pattern-like phase difference corresponding to each line of the liquid crystal cell. As means for expressing a pattern-like phase difference, a phase difference plate (pattern retarder) having a pattern of regions having different slow axis directions is known (for example, Patent Document 1).

  The pattern retarder as described above is usually arranged further on the viewing side of the viewing-side polarizing plate in the liquid crystal display device for stereoscopic (three-dimensional) image display. However, there may be a problem that crosstalk occurs under conditions such as heating and humidification (particularly when the function of the pattern retarder is imparted to the viewing-side protective layer of the viewing-side polarizing plate). Crosstalk means that each of the left and right images is mixed into the other image.

Japanese Patent No. 3372016

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a polarizing plate with a retardation layer capable of reducing crosstalk in stereoscopic image display.

The polarizing plate with a retardation layer of the present invention has a polarizing film having a thickness of 10 μm or less and a retardation layer disposed on one side of the polarizing film, and the retardation layers have slow axes in different directions. A plurality of regions having a predetermined pattern.
In a preferred embodiment, the in-plane retardation Re (590) of the retardation layer is 90 nm to 190 nm.
In a preferred embodiment, the predetermined pattern of the retardation layer has a stripe shape in which two regions having slow axes in different directions are alternately arranged.
In a preferred embodiment, each of the two regions having the slow axis in the different directions corresponds to one line of the liquid crystal cell.
In a preferred embodiment, the single transmittance of the polarizing film is 42.0% or more, and the degree of polarization is 99.9% or more.
In a preferred embodiment, the polarizing film is obtained by forming a polyvinyl alcohol resin layer on a thermoplastic resin base material to produce a laminate, and stretching the laminate in water in a boric acid aqueous solution.
In a preferred embodiment, the polarizing film forms a polyvinyl alcohol-based resin layer on a thermoplastic resin substrate to produce a laminate, and the laminate is stretched in air at 95 ° C. or higher. It is obtained by stretching in water in an aqueous boric acid solution.
According to another aspect of the present invention, a liquid crystal panel is provided. This liquid crystal panel has the above polarizing plate with a retardation layer.
According to another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes the liquid crystal panel.

  According to the present invention, a polarizing plate with a retardation layer capable of reducing crosstalk in stereoscopic image display can be obtained by combining a polarizing film having a thickness of 10 μm or less and a patterned retardation layer.

It is a schematic sectional drawing of the polarizing plate with a phase difference layer by preferable embodiment of this invention. It is a schematic sectional drawing of the polarizing plate with a phase difference layer by another preferable embodiment of this invention. It is a schematic sectional drawing of the laminated body by preferable embodiment. It is the schematic which shows an example of the manufacturing method of the polarizing film in the polarizing plate with a phase difference layer by preferable embodiment of this invention. It is a schematic plan view which shows an example of the pattern of the phase difference layer in the polarizing plate with a phase difference layer by preferable embodiment of this invention. It is a graph which shows the crosstalk rate of each Example and a comparative example.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
The in-plane retardation (Re) means an in-plane retardation value of a layer (film) at 23 ° C., and a wavelength of 590 nm unless otherwise specified. Re is obtained by Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Thickness direction retardation (Rth)
Thickness direction retardation (Rth) is a retardation value in the thickness direction of a layer (film) at a wavelength of 590 nm unless otherwise specified. Rth is determined by Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film).

A. FIG. 1 is a schematic sectional view of a polarizing plate with a retardation layer according to a preferred embodiment of the present invention. The polarizing plate 200 with a retardation layer includes a polarizing film 20, a retardation layer 30 disposed on one side (typically a viewing side) of the polarizing film 20, and a protective layer disposed on the other side of the polarizing film 20. 41 and a protective layer 42 disposed between the polarizing film 20 and the retardation layer 30. The retardation layer 30 is laminated on the protective layer 42 via the adhesive layer 60. An adhesive layer 50 is provided on the side of the protective layer 41 where the polarizing film 20 is not disposed. Typically, the polarizing plate 200 with a retardation layer is laminated on a liquid crystal cell (typically, the viewing side) with the adhesive layer 50 bonded thereto.

  FIG. 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another preferred embodiment of the present invention. The polarizing plate 300 with a retardation layer includes a polarizing film 20, a retardation layer 30 disposed on one side (typically a viewing side) of the polarizing film 20, and a protective layer disposed on the other side of the polarizing film 20. 41. An adhesive layer 50 is provided on the side of the protective layer 41 where the polarizing film 20 is not disposed. Typically, the polarizing plate 300 with a retardation layer is laminated on a liquid crystal cell (typically, the viewing side) with the adhesive layer 50 bonded thereto. The retardation layer 30 can function as a protective layer for the polarizing film 20.

B. Polarizing Film The polarizing film is typically a polyvinyl alcohol resin film in which a dichroic substance (preferably iodine) is adsorbed and oriented.

  Arbitrary appropriate resin can be employ | adopted for the said polyvinyl alcohol-type resin. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the polyvinyl alcohol resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. is there. The saponification degree can be determined according to JIS K 6726-1994. By using a polyvinyl alcohol resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.

  The average degree of polymerization of the polyvinyl alcohol resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

  The thickness of the polarizing film is preferably less than 15 μm, more preferably 10 μm or less, further preferably 7 μm or less, and particularly preferably 5 μm or less. On the other hand, the thickness of the polarizing film is preferably 0.5 μm or more, more preferably 1.5 μm or more. By using such a polarizing film, crosstalk can be reduced satisfactorily. As shown in FIG. 2, even when the retardation layer can function as a protective layer of the polarizing film (when the function of the pattern retarder is imparted to the protective layer), the crosstalk can be reduced satisfactorily. Specifically, such a polarizing film has a small dimensional change (shrinkage) under conditions such as heating and humidification, and the influence of the dimensional change of the polarizing film on the retardation layer (for example, dimensional change of the retardation layer). Can be reduced. As a result, it is possible to improve the problem that the pattern of the patterned retardation layer (pattern retarder) does not correspond to the line of the liquid crystal cell and crosstalk occurs.

  The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizing film is preferably 40.0% or more, more preferably 41.0% or more, further preferably 42.0% or more, and particularly preferably 42.3% or more. The polarization degree of the polarizing film is preferably 99.8% or more, more preferably 99.9% or more, and further preferably 99.95% or more.

  Any appropriate method can be adopted as a method of manufacturing the polarizing film. Typically, the polarizing film is produced by appropriately performing treatments such as dyeing, crosslinking, stretching, and drying on a polyvinyl alcohol resin film.

  In a preferred embodiment, the polarizing film is formed by forming a polyvinyl alcohol-based resin layer (film) on a thermoplastic resin substrate to produce a laminate (step A), and the laminate is stretched in water in a boric acid aqueous solution. (Step B). According to such an embodiment, polarized light having a small thickness (for example, 10 μm or less) and excellent optical characteristics (for example, a single transmittance of 42.0% or more and a degree of polarization of 99.9% or more). Membranes can be manufactured well. Hereinafter, this embodiment will be described.

(Process A)
In step A, a laminate is produced. FIG. 3 is a schematic cross-sectional view of a laminate according to a preferred embodiment. The laminate 10 includes a thermoplastic resin substrate 11 and a polyvinyl alcohol resin layer 12, and is produced by forming the polyvinyl alcohol resin layer 12 on the thermoplastic resin substrate 11. Any appropriate method can be adopted as a method of forming the polyvinyl alcohol-based resin layer 12. Preferably, the polyvinyl alcohol-type resin layer 12 is formed by apply | coating the coating liquid containing a polyvinyl alcohol-type resin on the thermoplastic resin base material 11, and drying.

  Arbitrary appropriate materials can be employ | adopted for the constituent material of the said thermoplastic resin base material. As a constituent material of the thermoplastic resin substrate, an amorphous (non-crystallized) polyethylene terephthalate resin is preferably used. Among these, amorphous (hard to crystallize) polyethylene terephthalate resin is particularly preferably used. Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol as a glycol.

  The thermoplastic resin base material absorbs water in the step B described later, and the water can act as a plasticizer to be plasticized. As a result, the stretching stress can be significantly reduced during stretching in water, the stretching can be performed at a high magnification, and the stretchability of the thermoplastic resin substrate can be superior to that during stretching in the air. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be produced. In one embodiment, the thermoplastic resin substrate preferably has a water absorption rate of 0.2% or more, and more preferably 0.3% or more. On the other hand, the water absorption rate of the thermoplastic resin substrate is preferably 3.0% or less, and more preferably 1.0% or less. By using such a thermoplastic resin substrate, it is possible to prevent problems such as the dimensional stability of the thermoplastic resin substrate being significantly reduced during production and the appearance of the resulting polarizing film being deteriorated. Moreover, it can prevent that a base material fractures | ruptures at the time of extending | stretching in water, or a polyvinyl-alcohol-type resin layer peels from a thermoplastic resin base material. In addition, the water absorption rate of a thermoplastic resin base material can be adjusted by introduce | transducing a modification group into a constituent material, for example. The water absorption is a value determined according to JIS K 7209.

  The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 170 ° C. or lower. By using such a thermoplastic resin substrate, the stretchability of the laminate can be sufficiently ensured while suppressing crystallization of the polyvinyl alcohol-based resin layer. Furthermore, in view of plasticizing the thermoplastic resin substrate with water and performing good stretching in water, the temperature is more preferably 120 ° C. or lower. In one embodiment, the glass transition temperature of the thermoplastic resin substrate is preferably 60 ° C. or higher. By using such a thermoplastic resin base material, the thermoplastic resin base material is deformed (for example, generation of irregularities, talmi, wrinkles, etc.) when the coating liquid containing the polyvinyl alcohol resin is applied and dried. Such a problem as described above can be prevented and a laminate can be produced satisfactorily. Further, the stretching of the polyvinyl alcohol-based resin layer can be favorably performed at a suitable temperature (for example, about 60 ° C.). In addition, the glass transition temperature of a thermoplastic resin base material can be adjusted by heating using the crystallizing material which introduce | transduces a modification group into a constituent material, for example. The glass transition temperature (Tg) is a value obtained according to JIS K7121.

  In another embodiment, a glass transition temperature lower than 60 ° C. may be used as long as the thermoplastic resin base material is not deformed when a coating solution containing a PVA resin is applied and dried. In this case, examples of the constituent material of the thermoplastic resin base material include olefin resins such as polypropylene and polymethylpentene.

  The thickness of the thermoplastic resin substrate before stretching is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. If it is less than 20 μm, it may be difficult to form a polyvinyl alcohol-based resin layer. If it exceeds 300 μm, it takes a long time for the thermoplastic resin substrate to absorb water in Step B, and an excessive load may be required for stretching.

  The coating solution is typically a solution obtained by dissolving the polyvinyl alcohol resin in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferable. The concentration of the polyvinyl alcohol resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the thermoplastic resin substrate can be formed.

  You may mix | blend an additive with a coating liquid. Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the resulting polyvinyl alcohol resin layer.

  Any appropriate method can be adopted as a coating method of the coating solution. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.).

  The coating / drying temperature of the coating solution is preferably 50 ° C. or higher.

  The thickness of the polyvinyl alcohol-based resin layer before stretching is preferably 3 μm to 20 μm.

  Before forming the polyvinyl alcohol-based resin layer, the thermoplastic resin substrate may be subjected to surface treatment (for example, corona treatment), or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By performing such treatment, the adhesion between the thermoplastic resin substrate and the polyvinyl alcohol-based resin layer can be improved.

(Process B)
In the step B, the laminate is stretched in water (stretching in boric acid solution). According to stretching in water, the thermoplastic resin substrate or the polyvinyl alcohol resin layer can be stretched at a temperature lower than the glass transition temperature (typically about 80 ° C.). It is possible to stretch at a high magnification while suppressing the formation. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be produced.

  Arbitrary appropriate methods can be employ | adopted for the extending | stretching method of a laminated body. Specifically, it may be fixed end stretching or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). The stretching of the laminate may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio (maximum draw ratio) of the laminate described later is the product of the draw ratios of the respective stages.

  The stretching in water is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid in water). By using a boric acid aqueous solution as the stretching bath, the polyvinyl alcohol-based resin layer can be given rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a polyvinyl alcohol resin by hydrogen bonding. As a result, rigidity and water resistance can be imparted to the polyvinyl alcohol-based resin layer, the film can be stretched satisfactorily, and a polarizing film having excellent optical properties (for example, polarization degree) can be produced.

  The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight with respect to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the polyvinyl alcohol-based resin layer can be effectively suppressed, and a polarizing film having higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

  When a dichroic substance (typically iodine) is adsorbed to the polyvinyl alcohol-based resin layer in advance by a dyeing process described later, preferably, an iodide is blended in the stretching bath (boric acid aqueous solution). . By compounding iodide, elution of iodine adsorbed on the polyvinyl alcohol-based resin layer can be suppressed. 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. Etc. Among these, potassium iodide is preferable. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight with respect to 100 parts by weight of water.

  The stretching temperature in Step B (liquid temperature of the stretching bath) is preferably 40 ° C to 85 ° C, more preferably 50 ° C to 85 ° C. If it is such temperature, it can extend | stretch at high magnification, suppressing melt | dissolution of a polyvinyl alcohol-type resin layer. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60 ° C. or higher in relation to the formation of the polyvinyl alcohol-based resin layer. In this case, when the stretching temperature is lower than 40 ° C., there is a possibility that stretching cannot be performed satisfactorily even in consideration of plasticization of the thermoplastic resin substrate with water. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the polyvinyl alcohol-based resin layer, which may result in failure to obtain excellent optical properties. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

  By employing underwater stretching (stretching in boric acid in water), a polarizing film that can be stretched at a high magnification and has excellent optical properties (for example, polarization degree) can be produced. Specifically, the maximum draw ratio is preferably 5.0 times or more with respect to the original length of the laminate. In this specification, the “maximum stretch ratio” refers to a stretch ratio immediately before the laminate is ruptured. Separately, a stretch ratio at which the laminate is ruptured is confirmed, and is a value 0.2 lower than the value. Moreover, the maximum draw ratio of the laminated body using the said thermoplastic resin base material can become higher in the direction which passed through the underwater extending | stretching process rather than extending | stretching only in air | atmosphere.

(Other processes)
Also in the present embodiment, as described above, other steps may be included in addition to the step A and the step B. Examples of other processes include an insolubilization process, a dyeing process, a crosslinking process, a stretching process (different from the above-described process B), a washing process, and a drying process (adjustment of moisture content). The other steps can be performed at any appropriate timing.

  The dyeing step is typically a step of dyeing the polyvinyl alcohol-based resin layer with a dichroic substance. Preferably, the dichroic substance is adsorbed on the polyvinyl alcohol-based resin layer. Examples of the adsorption method include a method of immersing a polyvinyl alcohol-based resin layer (laminate) in a staining solution containing a dichroic material, a method of applying the staining solution to a polyvinyl alcohol-based resin layer, The method of spraying on a polyvinyl alcohol-type resin layer etc. are mentioned. Preferably, the laminate is immersed in a staining solution containing a dichroic substance. It is because a dichroic substance can adsorb | suck favorably.

  As said dichroic substance, an iodine and a dichroic dye are mentioned, for example. Preferably, it is iodine. When iodine is used as the dichroic substance, the staining solution is an iodine aqueous solution. The compounding amount of iodine is preferably 0.1 part by weight to 0.5 part by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide to the aqueous iodine solution. Specific examples of the iodide are as described above. The blending amount of iodide is preferably 0.02 to 20 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of water. The liquid temperature during dyeing of the dyeing liquid is preferably 20 ° C. to 50 ° C. in order to suppress dissolution of the polyvinyl alcohol resin. When the polyvinyl alcohol-based resin layer is immersed in the staining solution, the immersion time is preferably 5 seconds to 5 minutes in order to ensure the transmittance of the polyvinyl alcohol-based resin layer. The staining conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or single transmittance of the finally obtained polarizing film is within a predetermined range. In one embodiment, immersion time is set so that the polarization degree of the polarizing film obtained may be 99.98% or more. In another embodiment, the immersion time is set so that the single transmittance of the obtained polarizing film is 40% to 44%.

  Preferably, the dyeing step is performed before step B.

  The insolubilization step is typically performed by immersing a polyvinyl alcohol resin layer in an aqueous boric acid solution. By performing the insolubilization treatment, water resistance can be imparted to the polyvinyl alcohol-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C to 40 ° C. Preferably, the insolubilization step is performed after the laminate is manufactured and before the dyeing step and the step B.

  The crosslinking step is typically performed by immersing the polyvinyl alcohol resin layer in an aqueous boric acid solution. By performing the crosslinking treatment, water resistance can be imparted to the polyvinyl alcohol-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a bridge | crosslinking process after the said dyeing | staining process, it is preferable to mix | blend iodide further. By compounding iodide, elution of iodine adsorbed on the polyvinyl alcohol-based resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the crosslinking step is performed before step B. In a preferred embodiment, the dyeing process, the crosslinking process and the process B are performed in this order.

  Examples of the stretching process different from the process B include a process of stretching the laminate in the air at a high temperature (for example, 95 ° C. or higher). Such an air stretching process is preferably performed before the process B (stretching in boric acid solution) and the dyeing process. Such an air stretching step can be positioned as preliminary or auxiliary stretching for boric acid water stretching, and is hereinafter referred to as “air-assisted stretching”.

  In some cases, the laminate can be stretched at a higher magnification by combining air-assisted stretching. As a result, a polarizing film having more excellent optical characteristics (for example, the degree of polarization) can be produced. For example, when a polyethylene terephthalate-based resin is used as the thermoplastic resin base material, it is preferable to combine the air auxiliary stretching and the boric acid water stretching rather than the boric acid water stretching alone. The film can be stretched while suppressing the orientation. As the orientation of the thermoplastic resin base material is improved, the stretching tension increases, so that stable stretching becomes difficult or the thermoplastic resin base material is broken. Therefore, the laminate can be stretched at a higher magnification by stretching while suppressing the orientation of the thermoplastic resin substrate.

  Moreover, the orientation of the PVA resin can be improved by combining the air-assisted stretching, whereby the orientation of the PVA resin can be improved even after the boric acid solution is stretched. Specifically, by previously improving the orientation of the PVA resin by air-assisted stretching, the PVA resin is easily cross-linked with boric acid during boric acid water stretching, and boric acid is a nodal point. It is presumed that the orientation of the PVA-based resin is increased even after stretching in boric acid solution by being stretched in such a state. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be produced.

  The stretching method for air-assisted stretching may be fixed-end stretching as in the above-mentioned step B, or free-end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). In addition, the stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio described below is the product of the draw ratios at each stage. The stretching direction in this step is preferably substantially the same as the stretching direction in step B above.

  The draw ratio in the air auxiliary drawing is preferably 3.5 times or less. The stretching temperature of the air auxiliary stretching is preferably equal to or higher than the glass transition temperature of the PVA resin. The stretching temperature is preferably 95 ° C to 150 ° C. In addition, the maximum draw ratio in the case of combining the air auxiliary stretching and the boric acid solution stretching is preferably 5.0 times or more, more preferably 5.5 times or more, and further preferably, the original length of the laminate. Is 6.0 times or more.

  The washing step is typically performed by immersing a polyvinyl alcohol resin layer in an aqueous potassium iodide solution. The drying temperature in the drying step is preferably 30 ° C to 100 ° C.

  FIG. 4 is a schematic view showing an example of a method for producing a polarizing film used in the present invention. The laminated body 10 is fed out from the feeding unit 100 and immersed in a boric acid aqueous solution bath 110 by rolls 111 and 112 (insolubilization step), and then the dichroic substance (iodine) and potassium iodide are rolled by rolls 121 and 122. It is immersed in the bath 120 of an aqueous solution (dyeing process). Subsequently, it is immersed in the bath 130 of the aqueous solution of boric acid and potassium iodide with the rolls 131 and 132 (crosslinking process). Thereafter, the laminate 10 is stretched by applying tension in the longitudinal direction (longitudinal direction) with the rolls 141 and 142 having different speed ratios while being immersed in the bath 140 of the boric acid aqueous solution (step B). The stretched laminate 10 is immersed in a potassium iodide aqueous solution bath 150 by rolls 151 and 152 (cleaning step) and subjected to a drying step (not shown). Thereafter, the laminate is wound up by the winding unit 160.

C. Retardation layer The retardation layer can typically function as a λ / 4 plate. The λ / 4 plate can convert linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The in-plane retardation Re (590) of such a retardation layer is preferably 90 nm to 190 nm, more preferably 100 nm to 170 nm, and further preferably 110 nm to 150 nm. The retardation layer preferably has a refractive index ellipsoid of nx>ny> nz or nx> ny = nz. In the present specification, “ny = nz” includes not only the case where ny and nz are exactly equal, but also the case where ny and nz are substantially equal.

  The retardation layer has a plurality of regions each having a slow axis in a different direction in a predetermined pattern. Typical examples of patterns include stripes, checkers, and mosaics. By having such a configuration, different images can be provided to the left and right eyes of the observer, and as a result, a three-dimensional (stereoscopic) image can be provided. In the present specification, for example, “the in-plane phase difference Re (590) is 140 nm” preferably means that the in-plane phase differences of the plurality of regions are each 140 nm. Typically, the retardation layer has two regions each having a slow axis in different directions in a predetermined pattern. Typically, the slow axis directions of the two regions are substantially orthogonal to each other. With such a configuration, the two regions can provide images having different polarization directions, and as a result, a good three-dimensional image can be provided.

  The predetermined pattern of the retardation layer preferably has a stripe shape in which two regions 31 and 32 each having a slow axis in different directions are alternately arranged as shown in FIG. The stripe direction may be the horizontal direction (left-right direction) of the display screen or the vertical direction (up-down direction). Similarly to the above, the slow axis directions of the two striped regions are substantially orthogonal to each other. Preferably, each of the two regions having the slow axis in the different directions corresponds to one line of the liquid crystal cell. In other words, the stripe width in the stripe pattern corresponds to one line of the liquid crystal cell. In this specification, “one line of a liquid crystal cell” refers to a vertical or horizontal line of pixels arranged in a matrix. The stripe pattern preferably has black stripes between adjacent regions. The black stripe can be preferably formed at a position corresponding to the black matrix of the liquid crystal cell. By providing black stripes, crosstalk can be further reduced.

  The slow axis direction of each region having a different slow axis direction in the retardation layer preferably has a relationship of substantially ± 45 ° with the absorption axis direction of the polarizing film. If the in-plane retardation of the retardation layer is within the above preferred range and the slow axis direction of each region and the absorption axis direction of the polarizing film have such a relationship, the left eye image and the right eye Since both of the images for use are circularly polarized light, a good stereoscopic image display can be realized.

  In one embodiment, the retardation layer comprises a plurality of regions each having a slow axis in a different direction formed by fixing a photocurable liquid crystal polymer in different alignment states on a base film. Have. Such a retardation layer is formed, for example, as follows: First, a photo-alignment film is formed on a base film, and an alignment regulating force is applied in a predetermined direction using a polarization exposure method. For example, a photo-alignment film having regions to which alignment regulating forces of + 45 ° and −45 ° are alternately applied to the stripe direction for each line of the liquid crystal cell is formed. Next, a photocurable liquid crystal polymer layer is formed on the photo-alignment film, and the photo-curable liquid crystal polymer layer is irradiated with ultraviolet rays to fix the alignment state of the liquid crystal polymer. (For example, two regions having + 45 ° and −45 ° slow axis directions alternately with respect to the stripe direction for each line of the liquid crystal cell). The in-plane retardation of the region can be adjusted in consideration of the in-plane retardation of the base film so that the in-plane retardation of the entire retardation layer is in the preferred range.

The linear expansion coefficient of the base film is preferably 5.0 × 10 ⁻⁴ (1 / ° C.) or less, more preferably 1.0 × 10 ⁻⁴ (1 / ° C.) or less. Examples of the material constituting the base film include a cyclic olefin resin, a polycarbonate resin, and a cellulose resin. The cyclic olefin-based resin is a general term for resins that are polymerized using a 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, copolymers of cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers. As said polycarbonate-type resin, arbitrary appropriate polycarbonate-type resins are used as long as the effect of this invention is acquired. For example, an aromatic polycarbonate composed of an aromatic dihydric phenol component and a carbonate component is preferably used.

  In another embodiment, the retardation layer may be formed from a polymer material containing a photoisomerization substance. Since the photoisomerized substance generates a structural isomer or a stereoisomer by light irradiation or the like, regions having different slow axis directions can be formed in a predetermined pattern by performing light irradiation in a predetermined pattern. The photoisomerizable material is typically any suitable photochromic compound having a photoisomerizable functional group. Specific examples include azobenzene compounds, benzaldoxime compounds, azomethine compounds, stilbene compounds, spiropyran compounds, spirooxazine compounds, fulgide compounds, diarylethene compounds, cinnamic acid compounds, retinal compounds, And hemithioindico compounds. Preferred are azobenzene compounds, spiropyran compounds, and cinnamic acid compounds, and particularly preferred are cinnamic acid compounds. Further, the photoisomerization substance may be a monomer or a polymer.

  Any appropriate polymer material can be adopted as the polymer material. Furthermore, the polymer material may preferably contain a polymerizable resin. By containing the polymerizable resin, the orientation of the photoisomerized substance can be fixed. In more detail, once the polymerizable resin is polymerized so as to fix the orientation of the photoisomerized substance by light irradiation or heating, the desired resin of the photoisomerization substance can be obtained even if further light irradiation or heating is performed. May not play a role in causing structural isomerization. That is, the polymerizable resin can always stably maintain the slow axis direction fixed in the retardation layer. Examples of such a polymerizable resin include a compound having an unsaturated double bond, a compound having an electrophilic group, a compound having a nucleophilic group, and a compound having a polymerizable liquid crystal structure.

  A method for forming a retardation layer using a polymer material containing a photoisomerization substance will be briefly described. First, a pretreatment sheet is formed from a composition containing the photoisomerization material, the polymer material, and, if necessary, a polysynthetic resin. Any appropriate method (for example, a solution casting method, a melt film forming method (melt extrusion method), a coating method) may be employed as a method for forming the pretreatment sheet. For example, when performing the melt film-forming method, the pretreatment sheet can be produced by melting the above composition at a predetermined temperature and casting it from a die to a cooling roll. The pretreatment sheet may be used in an unstretched state, but it can be preferably uniaxially stretched in a predetermined direction. By performing uniaxial stretching, the slow axis directions of the plurality of regions can be more evenly aligned by light irradiation described later. A method and conditions for uniaxial stretching (for example, a stretching ratio and a stretching temperature) can be appropriately selected by those skilled in the art.

  Next, the pretreatment sheet is irradiated with light having an irradiation intensity distribution to form a plurality of regions having different slow axis directions. As a method of irradiating light having an irradiation intensity distribution, a method of irradiating light through a mask having a predetermined pattern is typically mentioned. The irradiation light is preferably linearly polarized light. In this manner, it is possible to form a retardation layer having a plurality of regions each having a slow axis in a different direction in a predetermined pattern.

  The details of the retardation layer (retardation film) using a polymer material containing a photoisomerization substance are described in Japanese Patent No. 3372016, which description is incorporated herein by reference.

  The retardation layer is not limited to the above form, and any suitable form can be adopted as long as the effects of the present invention can be obtained. For example, a predetermined position in which a polyvinyl alcohol film is selectively amorphized in a plane to form a predetermined pattern (for example, a stripe pattern in which different regions in the slow axis direction are alternately arranged for each line). A pattern retarder film corresponding to a phase difference (for example, a half wavelength phase difference); on a layer in which a region of a predetermined wavelength (for example, a half wavelength) is formed in a predetermined pattern (for example, a stripe pattern), A pattern retarder film provided with a retardation layer having a predetermined wavelength (for example, ¼ wavelength) that is not patterned can be used as the retardation layer.

D. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer of a polarizing film. Specific examples of the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

Examples of the (meth) acrylic resin include poly (meth) acrylic esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, and methyl methacrylate- (meth) acrylic acid esters. Polymer, methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, And methyl methacrylate-cyclohexyl methacrylate copolymer and methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, poly (meth) acrylic acid C _1-6 alkyl such as poly (meth) acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  The weight average molecular weight of the (meth) acrylic resin is preferably 10,000 to 500,000. If the weight average molecular weight is too small, the mechanical strength when formed into a film tends to be insufficient. When the weight average molecular weight is too large, the viscosity at the time of melt extrusion is high, the molding processability is lowered, and the productivity of the molded product tends to be lowered.

  The glass transition temperature of the (meth) acrylic resin is preferably 110 ° C. or higher, more preferably 120 ° C. or higher. When the glass transition temperature is in such a range, durability and heat resistance can be excellent. The upper limit of the glass transition temperature is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a glutarimide structure is preferable as the (meth) acrylic resin in that the desired characteristics can be obtained. Examples of (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A-2006-328329. 2006-328334, JP-A 2006-337491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337469, JP-A 2007-009182, JP-A 2009- Nos. 161744 and 2010-284840. These descriptions are incorporated herein by reference.

In the first aspect, the glutarimide resin is preferably a unit represented by the following general formula (1) (hereinafter also referred to as a glutarimide unit) and a unit represented by the following general formula (2) (hereinafter, (Meth) acrylic acid ester unit).
In Formula (1), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms or an alkyl group having 3 to 12 carbon atoms. It is a substituent containing a cycloalkyl group or an aromatic ring having 5 to 15 carbon atoms. In Formula (2), R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or an alkyl group having 3 to 12 carbon atoms. It is a substituent containing a cycloalkyl group or an aromatic ring having 5 to 15 carbon atoms.

The glutarimide resin may further contain a unit represented by the following general formula (3) (hereinafter also referred to as an aromatic vinyl unit) as necessary.
In Formula (3), R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.

In the general formula (1), preferably, R ¹ and R ² are each independently hydrogen or a methyl group, R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and more preferably , R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

The glutarimide resin may include only a single type as a glutarimide unit, or may include a plurality of types in which R ¹ , R ² , and R ³ in the general formula (1) are different. Good.

  The glutarimide unit can be formed by imidizing the (meth) acrylic acid ester unit represented by the general formula (2). The glutarimide unit is an acid anhydride such as maleic anhydride, or a half ester of such an acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms; acrylic acid, methacrylic acid, maleic acid. It can also be formed by imidizing an α, β-ethylenically unsaturated carboxylic acid such as maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, citraconic acid and the like.

In the general formula (2), preferably, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, R ⁶ is hydrogen or a methyl group, and more preferably, R ⁴ is hydrogen. , R ⁵ is a methyl group, and R ⁶ is a methyl group.

The glutarimide resin may contain only a single type as a (meth) acrylic acid ester unit, or a plurality of types in which R ⁴ , R ⁵ and R ⁶ in the general formula (2) are different. May be included.

  The glutarimide resin preferably contains styrene, α-methylstyrene, and more preferably styrene as the aromatic vinyl constituent unit represented by the general formula (3). By having such an aromatic vinyl structural unit, the phase difference can be reduced.

The glutarimide resin may include only a single type as an aromatic vinyl structural unit, or may include a plurality of types in which R ⁷ and R ⁸ are different.

The content of the glutarimide unit in the glutarimide resin is preferably changed depending on, for example, the structure of R ³ . The content of the glutarimide unit is preferably 20% by weight or more, more preferably 20% by weight to 95% by weight, still more preferably 40% by weight to 90% by weight, based on the total repeating unit of the glutarimide resin. %, Particularly preferably 50 wt% to 80 wt%. When the content of the glutarimide unit is in such a range, the phase difference can be reduced.

  The content of the aromatic vinyl unit in the glutarimide resin can be appropriately set according to the purpose and desired characteristics. Depending on the application, the content of the aromatic vinyl unit may be zero. When an aromatic vinyl unit is contained, the content thereof is preferably 10% by weight or more, more preferably 10% by weight to 40% by weight, even more preferably, based on the total repeating unit of the glutarimide resin. It is 15 to 30% by weight, particularly preferably 15 to 25% by weight. If the content of the aromatic vinyl unit is within such a range, the heat resistance and mechanical strength can be excellent.

  The glutarimide resin may further be copolymerized with other units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit, if necessary. Examples of other units include units composed of nitrile monomers such as acrylonitrile and methacrylonitrile, and maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. Can be mentioned. These other units may be directly copolymerized or graft copolymerized in the glutarimide resin.

  In the second aspect, the glutarimide resin preferably includes a glutarimide unit represented by the following general formula (4) and a methyl methacrylate unit, and has an imidization ratio of 2.5 to 5.0%, 0. An acid value of .10 to 0.50 mmol / g and an acrylate unit content of less than 1% by weight.

In Formula (4), R ⁹ and R ¹⁰ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, R ¹¹ represents an alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms. Or an aryl group having 6 to 10 carbon atoms.

In the general formula (4), R ⁹ and R ¹⁰ are each independently hydrogen or a methyl group, R ¹¹ is preferably hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and R ⁹ is More preferably, it is a methyl group, R ¹⁰ is hydrogen, and R ¹¹ is a methyl group.

The glutarimide resin of the second aspect may contain only a single type as a glutarimide unit, or a plurality of types in which R ⁹ , R ¹⁰ , and R ¹¹ in the general formula (4) are different. May be included.

  The glutarimide resin of the second aspect is, for example, a step of heating and melting a polymethyl methacrylate resin and treating with 0.5 to 10 parts by weight of an imidizing agent with respect to 100 parts by weight of the polymethyl methacrylate resin. It can be obtained by the manufacturing method including. The acrylic ester units in the polymethyl methacrylate resin used are preferably less than 1% by weight.

  The polymethyl methacrylate resin is produced by polymerizing methyl methacrylate. In the polymerization step, in addition to methyl methacrylate, for example, methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, ( Benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like can be used in combination. In this case, the acrylate units are preferably less than 1% by weight. More preferably, the methyl acrylate units are less than 0.5% by weight.

  As a method of heating and melting the polymethyl methacrylate resin and treating with an imidizing agent, any conventionally known method can be used. For example, the method described in JP 2010-284840 is preferably used. obtain. According to this method, a glutarimide resin in which the ratio of glutarimide units, methyl methacrylate units, carboxylic acid or carboxylic anhydride units is controlled as desired can be easily obtained.

The imidation ratio in the glutarimide resin of the second aspect is represented by the ratio of glutarimide units to methyl methacrylate units. This ratio can be measured, for example, by NMR spectrum, IR spectrum, or other methods of glutarimide resin. The imidization rate in this specification is calculated | required as follows. That is, ¹ H-NMR
¹ H-NMR measurement of the resin was performed using BRUKER Avance III (400 MHz). From the peak area A derived from O-CH ₃ protons of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm and the peak area B derived from N-CH ₃ protons of glutarimide in the vicinity of 3.0 to 3.3 ppm, It is calculated by the following formula.

Im% = B / (A + B) × 100
Here, the “imidization rate” refers to the ratio of the imide carbonyl group in the total carbonyl group.

  The imidation ratio of the glutarimide resin of the second aspect is preferably 2.5% to 5.0%, more preferably 2.5% to 4.5%, and still more preferably 3.0% to 4. 5%. If the imidation ratio is within this range, a glutarimide resin excellent in heat resistance, transparency, moldability, and mechanical strength when processed into a film can be obtained.

  The acid value of the glutarimide resin of the second aspect represents the content of carboxylic acid units and carboxylic anhydride units in the resin. The acid value can be calculated by, for example, a titration method described in WO2005 / 054311 and JP-A-2005-23272.

  The acid value of the glutarimide resin of the second aspect is preferably 0.10 to 0.50 mmol / g, more preferably 0.15 to 0.45 mmol / g. If the acid value is within the above range, a glutarimide resin having an excellent balance of heat resistance, mechanical properties and molding processability can be obtained.

  The content of the acrylate unit in the glutarimide resin of the second aspect is preferably less than 1% by weight, more preferably less than 0.5% by weight. When the content of the acrylate unit is within the range, a glutarimide resin excellent in thermal stability can be obtained.

  In the glutarimide resin of the second aspect, other units other than the glutarimide unit, the methyl methacrylate unit, the carboxylic acid or carboxylic anhydride unit, and the acrylic ester unit are further copolymerized as necessary. Also good. Examples of other units include aromatic vinyl monomers such as styrene, nitrile monomers such as acrylonitrile and methacrylonitrile, maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. A structural unit obtained by copolymerizing a maleimide monomer can be exemplified. These other units may be directly copolymerized or graft copolymerized in the glutarimide resin.

The protective layer 42 disposed between the polarizing film 20 and the retardation layer 30 is preferably made of a cellulose resin, and more preferably TAC. By using a cellulose-based resin (particularly TAC) as the protective layer 42, the dimensional change of the retardation layer due to the dimensional change of the polarizing film is remarkably suppressed, and as a result, the crosstalk of the stereoscopic image display can be reduced well. . The protective layer 42 is preferably optically isotropic. In particular, it is preferable that the in-plane retardation Re is small. The linearly polarized light that has passed through the polarizing film 20 is typically converted into circularly polarized light by the retardation layer 30. However, the smaller the in-plane retardation of the protective layer 42, the better the conversion to circularly polarized light can be realized. Excellent stereoscopic image display can be realized. Specifically, the in-plane retardation Re (590) of the protective layer 42 is preferably 0 nm to 20 nm, more preferably 0 nm to 10 nm, and particularly preferably 0 nm to 6 nm. The thickness direction retardation Rth (590) of the protective layer 42 is preferably −100 nm to +100 nm, more preferably −70 nm to +70 nm, and particularly preferably −50 nm to +50 nm. Furthermore, the photoelastic coefficient (590) of the protective layer 42 is preferably 5.0 × 10 ⁻¹¹ m / N or less, more preferably 3.0 × 10 ⁻¹¹ m / N or less. When the photoelastic coefficient is within such a range, adverse effects on the stereoscopic image display can be suppressed.

  The protective layer 41 is preferably made of the (meth) acrylic resin. By using the (meth) acrylic resin as the protective layer 41, adverse effects on the display characteristics of the image display device can be suppressed. In this case, the in-plane retardation Re (590) of the protective layer 41 is preferably 0 nm to 10 nm, more preferably 0 nm to 7 nm, and particularly preferably 0 nm to 5 nm. The thickness direction retardation Rth (590) of the protective layer 41 is preferably −15 nm to +15 nm, more preferably −10 nm to +10 nm, and particularly preferably −5 nm to +5 nm. The protective layer 41 may be a stretched film or an unstretched film, but is preferably a stretched film.

  The thickness of the protective layer is preferably 20 μm to 100 μm.

  In addition, when employ | adopting the manufacturing method of the said polarizing film, you may use the obtained polarizing film in the state united with the said thermoplastic resin base material. In this case, the thermoplastic resin substrate can function as a protective layer.

E. Adhesive layer In the present specification, an “adhesive layer” refers to a layer that joins surfaces of adjacent optical members and integrates them with practically sufficient adhesive force and adhesion time. Examples of the material forming the adhesive layer include a pressure-sensitive adhesive, an adhesive, and an anchor coat agent. The adhesive layer may have a multilayer structure in which an anchor coat layer is formed on the surface of an adherend and an adhesive layer is formed thereon. Further, it may be a thin layer (also referred to as a hairline) that cannot be visually recognized.

  The thickness of the adhesive layer can be appropriately set according to the purpose. The thickness is preferably 2 μm to 50 μm, more preferably 2 μm to 40 μm, and particularly preferably 5 μm to 35 μm. By setting the thickness within such a range, an adhesive layer having appropriate adhesiveness can be obtained.

  The shear modulus at 20 ° C. of the adhesive layer is preferably 30000 Pa to 1100000 Pa, more preferably 40000 Pa to 1000000 Pa, still more preferably 50000 Pa to 900000 Pa, and particularly preferably 50000 Pa to 90000 Pa.

  The transmittance of the adhesive layer measured with light having a wavelength of 590 nm at 23 ° C. is preferably 90% or more. The theoretical upper limit of transmittance is 100%, and the practical upper limit is 96%.

  The gel fraction of the adhesive layer is preferably 75% or more, more preferably 75% to 90%, and particularly preferably 80% to 85%. By setting the gel fraction within such a range, an adhesive layer having good adhesive properties can be obtained. The gel fraction can be adjusted depending on the type and content of the crosslinking agent used.

  The glass transition temperature (Tg) of the adhesive layer is preferably −70 ° C. to −10 ° C., more preferably −60 ° C. to −15 ° C., and particularly preferably −50 ° C. to −20 ° C. By setting the glass transition temperature in such a range, an adhesive layer having strong adhesion to the retardation layer can be obtained.

  The moisture content of the adhesive layer is preferably 1.0% or less, more preferably 0.8% or less, particularly preferably 0.6% or less, and most preferably 0.4% or less. The theoretical lower limit of moisture content is zero. By setting the moisture content in such a range, it is possible to obtain an adhesive layer in which foaming does not easily occur even in a high temperature environment.

  The adhesive layer is preferably composed of an acrylic pressure-sensitive adhesive. The acrylic pressure-sensitive adhesive preferably contains a (meth) acrylic polymer and a peroxide. The (meth) acrylic polymer refers to a polymer or copolymer synthesized from an acrylate monomer and / or a methacrylate monomer. When the (meth) acrylic polymer is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a coalescence. A preferable molecular arrangement state of the (meth) acrylic polymer is a random copolymer.

  Any appropriate peroxide can be used as the peroxide as long as radicals can be generated by heating to achieve crosslinking of the (meth) acrylic polymer. Examples of the peroxide include hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, peroxydicarbonates, peroxyketals, and ketone peroxides. The amount of the peroxide is preferably 0.01 parts by weight to 1 part by weight, and more preferably 0.05 parts by weight to 0.8 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Particularly preferred is 0.1 to 0.5 parts by weight, and most preferred is 0.15 to 0.45 parts by weight. By setting the amount of the peroxide in such a range, an adhesive layer having appropriate stress relaxation properties and excellent thermal stability can be obtained.

F. Others In the polarizing plate with a retardation layer of the present invention, any appropriate surface treatment layer may be formed on the viewing side of the retardation layer depending on the purpose. Representative examples of the surface treatment layer include an antiglare layer, an antireflection layer, and a hard coat layer.

  The antiglare layer is provided for the purpose of, for example, preventing a reduction in the visibility of transmitted light due to reflection of external light on the surface of the image display device. The antiglare layer can be formed by imparting a fine concavo-convex structure to the film surface to be formed. A typical example of a material for forming the antiglare layer is a transparent resin. Specific examples include ultraviolet curable resins containing acrylic resins such as isocyanuric acid triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate, and urethane resins such as isophorone diisocyanate polyurethane. The provision of the fine concavo-convex structure is performed by any appropriate method. Typical examples include roughening (for example, sand blasting and embossing) and blending of fine particles. When fine particles are used, any appropriate fine particles can be adopted as the fine particles depending on the purpose. Preferably, it is a transparent fine particle. Specifically, the fine particles may be inorganic fine particles (for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, or antimony oxide fine particles that may be conductive), and organic fine particles ( For example, it may be a crosslinked or uncrosslinked polymer fine particle). The average particle diameter of the fine particles is preferably 0.5 μm to 20 μm. The amount of the fine particles is preferably 2 to 70 parts by weight, more preferably 5 to 50 parts by weight with respect to 100 parts by weight of the transparent resin.

  The hard coat layer is provided for the purpose of preventing scratches on the surface of a polarizing plate or the like disposed on the surface of the image display device. The hard coat layer is composed of a cured film having appropriate hardness and slipperiness. Examples of the material for forming the hard coat layer include a silicone resin in addition to the acrylic resin and the urethane resin that form the antiglare layer.

  The antireflection layer is provided for the purpose of preventing reflection of external light on the surface of the image display device. As the antireflection layer, an antireflection layer usually used in the art may be employed.

G. Liquid crystal panel The liquid crystal panel of this invention has the said polarizing plate with retardation layer. Preferably, the liquid crystal panel of the present invention includes a liquid crystal cell and the polarizing plate with a retardation layer disposed on the viewing side of the liquid crystal cell.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method of each characteristic is as follows.
1. Thickness Measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).
2. The water absorption rate of the thermoplastic resin substrate was measured according to JIS K 7209.
3. Glass transition temperature (Tg) of thermoplastic resin substrate
It measured according to JIS K7121.
4). Polarization degree Using a UV-visible spectrophotometer (manufactured by JASCO Corporation, product name “V7100”), the single transmittance (Ts), parallel transmittance (Tp) and orthogonal transmittance (Tc) of the polarizing film are measured. The degree of polarization (P) was determined by the following equation.
Polarization degree (P) (%) = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100
Note that Ts, Tp, and Tc are Y values measured with a two-degree field of view (C light source) of JIS Z 8701 and corrected for visibility.
5. Retardation The phase difference was measured using a product name “KOBRA-CCD” manufactured by Oji Scientific Instruments.

[Example 1]
(Preparation of polarizing film)
As the thermoplastic resin substrate, an amorphous polyethylene terephthalate (A-PET) film (trade name “Novaclear”, thickness: 100 μm, manufactured by Mitsubishi Plastics, Inc.) having a water absorption of 0.60% and a Tg of 80 ° C. was used.
A polyvinyl alcohol (PVA) resin having a polymerization degree of 2600 and a saponification degree of 99.9 mol% (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “GOHSENOL (registered trademark) NH-26”) on one side of the thermoplastic resin base group Was applied and dried at 60 ° C. to form a polyvinyl alcohol-based resin layer having a thickness of 7 μm. In this way, a laminate was produced.

The obtained laminate was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) (insolubilization step).
Subsequently, it was immersed for 60 seconds in the dyeing bath (the iodine aqueous solution obtained by mix | blending 0.2 weight part of iodine and 2 weight part of potassium iodide with respect to 100 weight part of water) of the liquid temperature of 30 degreeC. (Dyeing process).
Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking step).
Thereafter, the laminate is immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 60 ° C. However, uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds (stretching step). The immersion time in the boric acid aqueous solution was 120 seconds, and the draw ratio was 5.0 times.
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 parts by weight of water) and then dried with hot air at 60 ° C. (cleaning and drying) Process).
Thus, the laminated body in which the polarizing film with a thickness of 3 micrometers was formed on the thermoplastic resin base material was obtained. The obtained polarizing film had a single transmittance (Ts) of 42.2% and a degree of polarization (P) of 99.96%.

(Production of retardation layer)
A retardation film having two regions with different slow axis directions in a stripe pattern was produced as follows. A photo-alignment film is formed on a norbornene-based resin film (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.), and + 45 °, −45 with respect to the stripe direction for each line of the liquid crystal cell using a polarization exposure method. A photo-curable liquid crystal polymer layer having a predetermined birefringence and a film thickness was formed on the photo-alignment film by applying an alignment regulating force of 0 °. Next, a retardation film corresponding to a λ / 4 plate having two stripe-patterned regions having different slow axis directions by irradiating ultraviolet rays to cure the photocurable liquid crystal polymer and fixing its alignment state. (Pattern retarder film) was produced.

(Production of (meth) acrylic film)
A biaxial kneader containing 100 parts by weight of imidized MS resin and 0.62 part by weight of a triazine-based ultraviolet absorber (trade name: T-712, manufactured by Adeka Co., Ltd.) described in Production Example 1 of JP-A-2009-161744 Was mixed at 220 ° C. to prepare resin pellets. The obtained resin pellets were dried at 100.5 kPa and 100 ° C. for 12 hours, extruded from a T-die at a die temperature of 270 ° C. with a single screw extruder, and formed into a film (thickness: 160 μm). Furthermore, the film is stretched in an atmosphere of 150 ° C. in the transport direction (thickness 80 μm), and then stretched in an atmosphere of 150 ° C. in a direction orthogonal to the film transport direction to form a biaxially stretched film having a thickness of 40 μm. Obtained. The obtained film had an in-plane retardation Re (590) of 0.4 nm and a thickness direction retardation Rth (590) of 0.78 nm.

On the polarizing film side of the laminate obtained above, the (meth) acrylic film obtained above as an inner (liquid crystal cell side) protective layer is used as a water-soluble adhesive mainly composed of a polyvinyl alcohol resin (Japan). The products were bonded together through a product name “Gosefimmer Z200” manufactured by Synthetic Chemical Industry.
Next, the thermoplastic resin substrate was peeled off, and a TAC film (trade name “TD80UL”, manufactured by Fuji Film Co., Ltd., thickness 80 μm, Re (590) = 4 nm, Rth (590) = 45 nm) was bonded through a water-soluble adhesive (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name “Gosefimer Z200”) mainly composed of a polyvinyl alcohol resin. Subsequently, the pattern retarder film obtained above was bonded to the surface of the viewing-side protective layer via an acrylic pressure-sensitive adhesive (thickness: 23 μm). At this time, the lamination was performed so that the angle formed by the slow axis of the pattern retarder film and the absorption axis of the polarizing film was substantially ± 45 °.
Furthermore, an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) was formed on the inner protective layer surface.
In this way, a polarizing plate with a retardation layer having a configuration of pressure-sensitive adhesive layer / (meth) acrylic film / polarizing film / TAC film / pressure-sensitive adhesive layer / retardation layer was obtained.

[Example 2]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that the following polarizing film (laminate) was used.
(Preparation of polarizing film)
As a thermoplastic resin substrate, an isophthalic acid copolymerized polyethylene terephthalate film (thickness: 200 μm) obtained by copolymerizing 6 mol% of isophthalic acid having a water absorption of 0.75% and Tg of 75 ° C. was used.
An aqueous solution having a concentration of 4 to 5% by weight obtained by dissolving a PVA resin powder having a polymerization degree of 1000 or more and a saponification degree of 99% or more in water is applied to one surface of the thermoplastic resin substrate, It dried at temperature, the 9-micrometer-thick PVA-type resin layer was formed, and the laminated body was produced.

The obtained laminate was uniaxially stretched free end uniaxially 2.0 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. (air-assisted stretching step).
Thereafter, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by blending 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization step).
Next, it is immersed in a staining solution containing potassium iodide at an iodine concentration of 0.12 to 0.25 wt% at a liquid temperature of 30 ° C. so that the single transmittance of the finally obtained polarizing film is 40 to 44%. (Dyeing process). Here, the mixing ratio of iodine and potassium iodide was 1: 7.
Subsequently, it was immersed for 60 seconds in a crosslinking bath having a liquid temperature of 40 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking step).
Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 75 ° C. However, free end uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds (stretching step). The draw ratio at this time was 3.0 times.
Thereafter, the laminate was immersed in a washing bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) for 5 seconds and then dried with hot air at 60 ° C. (washing). -Drying process).
Thus, the laminated body in which the polarizing film with a thickness of 3.5 micrometers was formed on the thermoplastic resin base material was obtained. The obtained polarizing film had a single transmittance (Ts) of 42.6% and a degree of polarization (P) of 99.99%.

When the polarizing plate with retardation layer obtained in Example 1 and Example 2 is bonded to a liquid crystal panel (LG Electronics, model number: 42LW6500) and left in a high temperature environment of 80 ° C. for 500 hours, when displaying black The brightness at the time of white display was measured, and the crosstalk rate was determined by the following formula.
Crosstalk rate = (Luminance when displaying odd line black and even line white)-(Luminance when displaying both odd line and even line black) / (Luminance when displaying odd line white display and even line black)-(Odd number (Brightness when both lines and even lines are displayed in black)
According to the polarizing plate with a retardation layer obtained in Example 1 and Example 2, the crosstalk rate was extremely low at 4% or less.

[Example 3]
In the production of the polarizing film, a polyvinyl alcohol resin layer having a thickness of 14 μm was formed, and a polarizing film having a thickness of 5 μm (Ts: 42.2%, P: 99.96%) was formed in the same manner as in Example 1. Thus, a polarizing plate with a retardation layer was obtained.

[Example 4]
In producing the polarizing film, a polyvinyl alcohol resin layer having a thickness of 18 μm was formed, and a polarizing film having a thickness of 7 μm (Ts: 42.2%, P: 99.96%) was formed in the same manner as in Example 1. Thus, a polarizing plate with a retardation layer was obtained.

[Example 5]
In producing the polarizing film, a polyvinyl alcohol resin layer having a thickness of 21 μm was formed, and a polarizing film having a thickness of 9 μm (Ts: 42.2%, P: 99.96%) was formed in the same manner as in Example 1. Thus, a polarizing plate with a retardation layer was obtained.

[Comparative Example 1]
A polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that a polarizing film obtained by the following method was used as the polarizing film.
(Preparation of polarizing film)
A polymer film (made by Kuraray Co., Ltd., trade name “VF-PS # 7500”) containing a polyvinyl alcohol resin having a thickness of 60 μm as a main component is placed in 5 baths under the following conditions (1) to (5). The film was immersed while applying tension in the longitudinal direction, and stretched so that the final stretching ratio was 6.2 times the original film length. This stretched film was dried for 1 minute in a 40 degree air circulation drying oven to produce a polarizing film having a thickness of 29 μm.
<Conditions>
(1) Swelling bath: 30 degree pure water.
(2) Dyeing bath: 30 degree aqueous solution containing 0.035 parts by weight of iodine with respect to 100 parts by weight of water and 0.2 parts by weight of potassium iodide with respect to 100 parts by weight of water.
(3) First cross-linking bath: 40 ° C. aqueous solution containing 3% by weight potassium iodide and 3% by weight boric acid.
(4) Second crosslinking bath: 60 ° C. aqueous solution containing 5% by weight potassium iodide and 4% by weight boric acid.
(5) Washing bath: 25 degree aqueous solution containing 3% by weight of potassium iodide.

(Crosstalk rate)
The polarizing plate with the retardation layer obtained in Examples 3 to 5 and Comparative Example 1 was bonded to a liquid crystal panel (LG Electronics, model number: 42LW6500), and left for 500 hours in a high-temperature environment at 80 ° C. The luminance at the time of display and at the time of white display was measured, and the crosstalk rate was obtained by the following formula.
Crosstalk rate = (Luminance when displaying odd line black and even line white)-(Luminance when displaying both odd line and even line black) / (Luminance when displaying odd line white and even line black)-(Odd number (Brightness when both lines and even lines are displayed in black)

  The measurement result of the crosstalk rate is shown in FIG. Practically, the crosstalk rate is required to be 20% or less, but each example was an excellent value of 10% or less.

  The polarizing plate with a retardation layer of the present invention can be suitably used for a liquid crystal display device. In particular, it can be suitably used as a viewing side polarizing plate of a three-dimensional liquid crystal display device.

DESCRIPTION OF SYMBOLS 20 Polarizing film 30 Retardation layer 41 Protective layer 42 Protective layer 50 Adhesive layer 60 Adhesive layer 200 Polarizing layer with retardation layer 300 Polarizing plate with retardation layer

Claims (5)

A polarizing film having a thickness of 10 μm or less and a retardation layer disposed on one side of the polarizing film, the retardation layer having a plurality of regions each having a slow axis in a different direction in a predetermined pattern A method for producing a polarizing plate with a retardation layer,
A polyvinyl alcohol resin layer is formed on a thermoplastic resin substrate composed of a polyethylene terephthalate resin to produce a laminate, and the laminate is stretched in air at 95 ° C. or higher. Including the step of obtaining the polarizing film by stretching in water in an acid aqueous solution,
A method for producing a polarizing plate with a retardation layer.   The manufacturing method of Claim 1 whose in-plane phase difference Re (590) of the said phase difference layer is 90 nm-190 nm.   The manufacturing method according to claim 1, wherein the predetermined pattern of the retardation layer has a stripe shape in which two regions having slow axes in different directions are alternately arranged.   The manufacturing method according to claim 1, wherein each of the two regions having a slow axis in the different direction corresponds to one line of the liquid crystal cell.   The manufacturing method according to any one of claims 1 to 4, wherein the polarizing film has a single transmittance of 42.0% or more and a degree of polarization of 99.9% or more.