JP2015022245A - Method for manufacturing retardation plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation plate capable of enhancing flexibility of a bonding angle when a circular polarizing lens for right and left eye 3D passive glasses is formed by laminating a polarizing plate and a retardation plate and applied to polarizing glasses extremely excellent in visibility when a 3D video is observed.SOLUTION: The method for manufacturing a retardation plate consisting of a biaxially oriented vinyl alcohol based film includes heat-treating the biaxially oriented vinyl alcohol based film in at least two stages. The heating temperature of the first stage is 130-180°C, and the heating temperature of the second stage is 160-210°C. The heating temperature of the second stage is higher by 5°C or more than the heating temperature of the first stage.

Description

  The present invention relates to a method of manufacturing a retardation plate, and more particularly, when observing image light of a left-eye image and image light of a right-eye image emitted from one image display unit as a three-dimensional (3D) image. The present invention relates to a method of manufacturing a retardation plate that is particularly effective for polarized glasses worn by a person.

  In recent years, various stereoscopic image display devices using a three-dimensional (3D) image system have been studied. A three-dimensional (3D) video system is a system that can recognize three-dimensional video with pop-out and depth, and displays two images with parallax on a screen or display, which differs depending on the left and right eyes of the observer. By showing the video, "depth" and "jump out" are expressed.

  The 3D video system is roughly divided into a glasses type and a naked eye type. However, since the naked eye type is difficult to increase in size and it is difficult to obtain a stereoscopic effect, a glasses type is widely used. In the glasses type, the left and right images are displayed on the adjacent pixels in the time difference division method (active glasses method) and pixel division, which alternately switches between the right eye image and the left eye image, passed through a polarizing filter, and passed through circularly polarized glasses. Can be divided into passive eyeglasses that enable stereoscopic viewing. Among them, in recent years, the demand for passive eyeglasses with less eye fatigue has increased, and further improvements have been demanded, and various types of polarized glasses have been proposed (see, for example, Patent Documents 1 and 2).

  In the passive glasses method, a pull-push type electro-optic liquid crystal modulator that switches between right-handed and left-handed polarized light is placed in front of the projection lens, so that only the designated frames on the left and right are seen in the opposite direction. By passing spectacles (passive spectacles) fitted with circularly polarized lenses that are polarized in the direction, a stereoscopic image with depth can be recognized.

  And, as a display method of the passive glasses type display, a patterning circularly polarizing plate composed of a retardation plate and a linear polarizing plate patterned for the right image and the left image according to the line width of the display is bonded to the display, A stereoscopic image with depth can be recognized by passing through glasses with a circularly polarized lens.

JP 2008-170557 A JP 2010-151954 A

  However, in the spectacles used in the above passive spectacle system, a phase difference plate made of polycarbonate resin, acetate resin, or alicyclic olefin resin is currently used for a circularly polarizing lens for 3D passive spectacles. The films made of these resins have different retardation values for each wavelength, and have the property that the retardation value increases as the wavelength becomes shorter and the retardation value becomes smaller as the wavelength becomes longer. For this reason, problems remain such that the transmittance changes at the respective wavelengths of R (red), G (green), and B (blue), resulting in a decrease in color reproducibility.

  Moreover, when a circularly polarizing lens for 3D passive glasses for the right eye or the left eye is formed by laminating a polarizing plate and a phase difference plate using the phase difference plate made of the resin material described above, it is conventionally performed. It was necessary to set the bonding angle between the absorption axis of the polarizing plate and the slow axis of the retardation plate to 45 °, and production management such as angle adjustment had to be sufficiently controlled. .

  Therefore, in the present invention, under such a background, when a polarizing plate and a retardation plate are laminated to form a circularly polarizing lens for right-eye or left-eye 3D passive spectacles, the absorption axis and retardation of the polarizing plate are used. It is not necessary that the bonding angle with the slow axis of the plate be exactly 45 °, the degree of freedom of the bonding angle is large, and polarization with excellent visibility when observing 3D images An object of the present invention is to provide a retardation plate that can be used for eyeglasses.

  However, as a result of intensive studies in view of such circumstances, the present inventors have conducted heat treatment in at least two stages on the biaxially stretched vinyl alcohol film when the biaxially stretched vinyl alcohol film is used as a retardation plate. By using this film, the degree of freedom of the bonding angle between the absorption axis of the polarizing plate and the slow axis of the retardation plate is large, and the polarization is very excellent when viewing a 3D image. The present invention has been completed by finding a retardation plate that can be used for eyeglasses.

  That is, the gist of the present invention is a method for producing a retardation plate comprising a biaxially stretched vinyl alcohol film, wherein the biaxially stretched vinyl alcohol film is heat treated in at least two stages, and the first stage heat treatment temperature is The present invention relates to a method for producing a retardation plate at 130 to 180 ° C., wherein the second stage heat treatment temperature is 160 to 210 ° C., and the second stage heat treatment temperature is 5 ° C. higher than the first stage heat treatment temperature. Is.

  When the retardation plate obtained by the present invention is formed by laminating a polarizing plate and a retardation plate to form a circularly polarizing lens for right-eye or left-eye 3D passive spectacles, the absorption axis of the polarizing plate and the retardation plate The bonding angle with the slow axis does not need to be precisely 45 °, and the degree of freedom of the bonding angle is large. In addition, when used for polarized glasses, visibility is improved when observing 3D images. It has a very excellent effect.

The present invention is described in detail below.
The present invention is a method for producing a retardation plate comprising a biaxially stretched vinyl alcohol film, wherein the biaxially stretched vinyl alcohol film is heat treated in at least two stages, and the first stage heat treatment temperature is 130 to 180 ° C. The second-stage heat treatment temperature is 160 to 210 ° C., and the second-stage heat treatment temperature is 5 ° C. higher than the first-stage heat treatment temperature. In such a heat treatment step, only one step of heat treatment increases the optical spots of the film and does not exhibit the effects of the present invention.

  The biaxially stretched vinyl alcohol film used in the present invention is a biaxially stretched vinyl alcohol film formed from a vinyl alcohol resin.

  The vinyl alcohol resin is not particularly limited as long as it has a vinyl alcohol unit obtained by saponifying a vinyl ester unit, and preferably has an average saponification degree of 90 mol% or more, particularly preferably 95 mol% or more, and more preferably. The vinyl alcohol resin is 99 mol% or more, and examples of the vinyl alcohol resin include a polyvinyl alcohol resin (hereinafter sometimes abbreviated as PVA resin) and an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH resin). In particular, it is preferable to use a PVA resin from the viewpoint of the visibility of 3D images. Furthermore, examples of the PVA resin include PVA obtained by homopolymerizing vinyl acetate and saponification thereof, and modified PVA. Examples of such modified PVA include copolymer modified products and post-modified products. it can.

As the vinyl alcohol film, a film made of a known PVA resin or EVOH resin can be used, and these resins will be described below.
First, the PVA resin will be described.

  Examples of the PVA resin include PVA and modified PVA as described above, and PVA is produced by homopolymerizing vinyl acetate and further saponifying it. The modified PVA is produced by copolymerizing an unsaturated monomer copolymerizable with vinyl acetate and vinyl acetate, and then saponified, and the amount of modification is within a range that does not impair the effects of the present invention. And is usually less than 10 mol%.

  Examples of the unsaturated monomer copolymerizable with vinyl acetate include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, 3-buten-1-ol, and 4-pentene. Derivatives such as hydroxy group-containing α-olefins such as -1-ol and 5-hexen-1-ol and acylated products thereof, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid Unsaturated acids such as, salts thereof, monoesters or dialkyl esters, amides such as diacetone acrylamide, acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof, Etc.

  Further, as the PVA resin, a PVA resin having a 1,2-diol structure in the side chain can also be used, and the PVA resin having a 1,2-diol structure in the side chain is, for example, (a) acetic acid A method of saponifying a copolymer of vinyl and 3,4-diacetoxy-1-butene, (a) a method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, and (c) vinyl acetate. Of saponifying and deketalizing a copolymer of 2,2-dialkyl-4-vinyl-1,3-dioxolane, and (d) saponifying a copolymer of vinyl acetate and glycerol monoallyl ether. Obtained by a method, etc.

  Furthermore, as modified PVA, it can also manufacture by post-modifying PVA. Examples of such post-modification methods include a method of converting PVA into acetoacetate ester, acetalization, urethanization, etherification, grafting, phosphoric esterification, and oxyalkylene.

In this invention, it is preferable that the average saponification degree of the said PVA-type resin is 90 mol% or more, The more preferable range is 95-100 mol%, The especially preferable range is 99-99.9 mol%. If the average saponification degree is too low, the moisture resistance of the film tends to decrease, and it is preferable to select a relatively high one.
The average saponification degree is measured according to JIS K 6726.

Moreover, it is preferable that the average degree of polymerization of the said PVA-type resin is 1100 or more, Furthermore, it is 1100-4000, Especially it is 1200-2600. If the average degree of polymerization is too low, the mechanical strength of the film tends to decrease. If the average degree of polymerization is too high, the processability during film formation and stretching tends to be reduced.
The average degree of polymerization is measured according to JIS K 6726.

Moreover, as a viscosity of the 4 weight% aqueous solution of the said PVA-type resin, 10-80 mPa * s (20 degreeC) is preferable, Furthermore, 15-70 mPa * s (20 degreeC), Especially 20-60 mPa * s (20 degreeC). ) Is preferred. If the viscosity is too low, mechanical properties such as film strength tend to decrease, and if it is too high, film-forming properties on the film tend to decrease.
The viscosity is measured according to JIS K 6726.

  These PVA resins can be used alone or in combination of two or more.

Next, the EVOH resin will be described.
The EVOH-based resin is usually obtained by saponifying a copolymer of 20 to 60 mol% ethylene and vinyl ester, and vinyl acetate is a typical example of such a vinyl ester. Other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used. Further, the EVOH-based resin may contain 0.0002 to 0.2 mol% of a vinyl silane compound as a copolymerization component in order to improve stability during heat melting. Here, examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other copolymerizable monomers such as propylene, butylene; unsaturated (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, etc., as long as the object of the present invention is not inhibited. Carboxylic acid or an ester thereof; vinyl pyrrolidone such as N-vinyl pyrrolidone can be copolymerized.

Although the ethylene content of the EVOH-based resin is 20 to 60 mol%, from the viewpoint of obtaining good stretchability, the ethylene content is particularly preferably 25 mol% or more, more preferably 30 mol% or more. Further, from the viewpoint of the strength of the film, the ethylene content is particularly preferably 55 mol% or less, and further preferably 50 mol% or less. If the ethylene content is too small, the melt moldability tends to decrease, and if it is too large, the solvent resistance tends to decrease.
In addition, the ethylene content of the EVOH resin can be obtained by a nuclear magnetic resonance (NMR) method.

Moreover, the average saponification degree of such EVOH resin is preferably 90 mol% or more, more preferably 95 mol% or more, and further preferably 99 mol% or more. When the average saponification degree is too low, the solvent resistance tends to be lowered.
Here, when the EVOH-based resin is composed of a blend of two or more types of EVOH-based resins having different saponification degrees, the average value calculated from the blending weight ratio is defined as the saponification degree.

  Furthermore, a boron compound can be blended with the EVOH resin in order to improve the stability at the time of heating and melting within a range that does not obstruct the object of the present invention. Examples of the boron compound include boric acids, boric acid esters, borates, borohydrides, and the like. Specific examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid. Examples of boric acid esters include triethyl borate and trimethyl borate. Examples include alkali metal salts of acids, alkaline earth metal salts, and borax. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferable.

  When a boron compound is blended with an EVOH-based resin, the content of the boron compound is preferably 20 to 2000 ppm, more preferably 50 to 1000 ppm in terms of boron element. By blending the boron compound within this range, it is possible to obtain an EVOH-based resin in which torque fluctuation during heating and melting is suppressed. If the content of the boron compound is too small, the effect of addition is small, and if it is too large, gelation tends to occur and the moldability may be poor.

  A suitable melt flow rate (MFR) (230 ° C., under a load of 2160 g) of such EVOH-based resin is usually 1 to 50 g / 10 minutes, more preferably 3 to 40 g / 10 minutes, and further preferably 5 to 5 g. 30 g / 10 minutes. These EVOH resins can be used alone or in a mixture of two or more.

  In the present invention, the vinyl alcohol resin is used to form a film. However, such a film forming method may be a known one. For example, a vinyl alcohol resin solution is allowed to flow on a metal surface such as a drum or an endless belt. The film is formed by a cast molding method in which a film is formed by stretching, or a melt molding method in which melt extrusion is performed by an extruder.

Such a vinyl alcohol film is biaxially stretched and used as a biaxially stretched vinyl alcohol film.
Such a stretching treatment method can be carried out in accordance with a known method such as simultaneous biaxial stretching and sequential biaxial stretching that are usually performed, but sequential biaxial stretching is preferred in terms of the degree of freedom of stretching operation, and in particular after longitudinal uniaxial stretching. Sequential biaxial stretching in which transverse uniaxial stretching is performed is preferable.
The draw ratio is 1.5 to 4.5 times in the longitudinal direction, particularly 2 to 4 times, more preferably 2.5 to 3.5 times in the transverse direction in terms of film strength and film surface smoothness. The draw ratio of 1.5 to 4.5 times, particularly 2 to 4 times, more preferably 2.5 to 3.5 times.

  In the present invention, among such biaxially stretched vinyl alcohol films, a biaxially stretched PVA film and a biaxially stretched EVOH film are preferably used, and in particular, a biaxially stretched PVA film is also preferred in terms of heat resistance. . The specific manufacturing method of these biaxially stretched films is demonstrated.

  First, the biaxially stretched PVA resin film will be described.

  A PVA film (PVA film before stretching) is formed using the PVA resin. Usually, a PVA resin-water composition having a PVA resin concentration of 5 to 70% by weight, preferably 10 to 60% by weight, is prepared as a stock solution for film formation.

  Such PVA-based resin-water compositions include plasticizers of polyhydric alcohols such as ethylene glycol, glycerin, polyethylene glycol, diethylene glycol, and triethylene glycol, phenolic, amine-based, and the like as long as the effects of the present invention are not impaired. Add appropriate additives such as antioxidants, stabilizers such as phosphate esters, colorants, fragrances, extenders, defoamers, release agents, UV absorbers, inorganic powders, surfactants, etc. There is no problem. Moreover, you may mix other water-soluble resins other than PVA-type resin, such as starch, carboxymethylcellulose, methylcellulose, and hydroxymethylcellulose.

  The method for forming the PVA film is not particularly limited, but after the PVA resin-water composition is supplied to an extruder and melt-kneaded, the film is extruded by the T-die method or the inflation method and dried. Is preferred.

  The melt kneading temperature in the extruder in such a method is preferably 55 to 160 ° C. If the temperature is too low, the film skin will be defective, and if it is too high, the foaming phenomenon tends to occur. Moreover, about the drying of the film after film forming, it is preferable to carry out at 70-120 degreeC, and also it is preferable to carry out at 80-100 degreeC.

The PVA film obtained above is further biaxially stretched, preferably sequentially biaxially stretched, so that the biaxially stretched PVA film used in the present invention is obtained.
For such biaxial stretching, the stretching ratio in the machine flow direction (MD direction) is 1.5 to 4.5 times, and the stretching ratio in the width direction (TD direction) is 1.5 to 4.5 times. Preferably, the draw ratio in the MD direction is preferably 2 to 4 times, the draw ratio in the TD direction is 2 to 4 times, more preferably the draw ratio in the MD direction is 2.5 to 3.5 times, and the draw ratio in the TD direction. Is 2.5 to 3.5 times. If the draw ratio in the MD direction is too low, it is difficult to improve physical properties due to stretching and the heat resistance tends to be impaired. If it is too high, the film tends to tear in the MD direction. Further, if the stretching ratio in the TD direction is too low, it is difficult to obtain physical properties by stretching, and the heat resistance tends to be impaired. If it is too high, breakage during stretching tends to occur frequently when the film is industrially produced. is there.

  In performing such sequential biaxial stretching or simultaneous biaxial stretching, it is preferable to adjust the water content of the PVA-based film to 5 to 30% by weight, particularly 10 to 25% by weight. The moisture content can be adjusted by a method in which the PVA film before drying is subsequently dried, a method in which a PVA film having a moisture content of less than 5% by weight is immersed in water, or is conditioned. Even if the moisture content is too low or too high, there is a tendency that the stretching ratio in the MD direction and the TD direction cannot be increased in the stretching process.

Next, the biaxially stretched EVOH film will be described.
An EVOH film (an EVOH film before stretching) is formed using the EVOH resin.

  Such EVOH-based resin includes an antioxidant, a colorant, an ultraviolet absorber, a slip agent, an antistatic agent, a plasticizer, a crosslinking agent such as boric acid, an inorganic filler, and the like within a range that does not interfere with the object of the present invention. You may mix | blend various resins, such as various additives, such as an inorganic desiccant, polyamide, polyolefin, and a super absorbent polymer.

When forming an EVOH film using the EVOH resin, melt molding is mainly used. The melt molding method will be described below.
The conditions at the time of melt molding are not particularly limited, but are usually formed by extrusion using a non-vented, screw-type extruder at a melting temperature of 190 to 250 ° C. Usually, a screw having a compression ratio of 2.0 to 4.5 is used to form a film using a T die or a round die.

  Thus, an EVOH film can be obtained, and the film can be further biaxially stretched, preferably sequentially biaxially stretched to obtain a biaxially stretched EVOH film.

  As for the draw ratio of such biaxial stretching, the draw ratio in the machine flow direction (MD direction) is 1.5 to 4.5 times, and the draw ratio in the width direction (TD direction) is 1.5 to 4.5 times. It is preferable that the draw ratio in the MD direction is preferably 2 to 4 times, the draw ratio in the TD direction is 2 to 4 times, more preferably the draw ratio in the MD direction is 2.5 to 3.5 times, and the TD direction. It is important that the draw ratio is 2.5 to 3.5 times from the viewpoint of film uniformity and mechanical strength. As the stretching method, a known stretching method such as a biaxial stretching method such as a double bubble method, a tenter method, a roll method, or the like can be adopted, and simultaneous stretching or sequential stretching is preferable, and sequential biaxial stretching is particularly preferable. .

  Moreover, easy continuous stretching is possible by pre-hydrating the original film before stretching, and the moisture content of the original film before stretching is preferably 2 to 30% by weight, particularly 5 to 25% by weight. % Is preferable, and further 10 to 20% by weight is preferable. If the moisture content is too low, stretch spots are likely to remain, and particularly when stretched with a tenter, the stretch ratio in the portion close to the grip becomes high, so that tearing near the grip may easily occur. On the other hand, if the moisture content is too high, the elastic modulus of the stretched portion is low, the difference from the unstretched portion is not sufficient, and stretched spots may remain easily.

  The stretching temperature varies somewhat depending on the moisture content of the original film before stretching, but a range of 50 to 130 ° C. is generally applicable. Particularly in simultaneous biaxial stretching, a biaxially stretched EVOH-based film with little thickness unevenness is easily obtained in the range of 70 to 100 ° C., and in sequential biaxial stretching, 70 to 100 ° C. in longitudinal stretching with a roll. By performing the stretching in the width direction with a tenter in the temperature range of 80 to 120 ° C., a biaxially stretched EVOH-based film with few thickness spots is easily obtained.

  In the present invention, it is important to perform heat treatment in at least two stages on the biaxially stretched vinyl alcohol film such as the biaxially stretched PVA film and the biaxially stretched EVOH film obtained above.

  In such a two-step heat treatment, the heat treatment temperature of the first step needs to be 130 to 180 ° C., particularly preferably 135 to 175 ° C., from the viewpoint of the wavelength dispersion characteristics of the birefringence retardation of the obtained film. More preferably, it is 140 to 170 ° C., and the heat treatment temperature in the second stage needs to be 160 to 210 ° C. from the viewpoint of wavelength dispersion characteristics of the birefringence retardation of the obtained film, and is particularly preferable. Is 165 to 205 ° C, more preferably 170 to 200 ° C. If the heat treatment temperature at the first stage is too low, the slow axis becomes non-uniform, and if it is too high, the slow axis becomes non-uniform. If the heat treatment temperature in the second stage is too low, the strength of the film will be reduced, and if it is too high, the visibility of 3D images will be reduced.

In addition, it is important that the second-stage heat treatment temperature is higher by 5 ° C. or more than the first-stage heat treatment temperature in order to make the slow axis uniform, and is preferably a temperature higher by 10 ° C. or more. The temperature is preferably 20 ° C or higher, and the upper limit of the temperature difference is usually 50 ° C. If the temperature difference is too small, the slow axis becomes non-uniform.
In the present invention, the heat treatment temperature is an atmospheric temperature when the film passes and can be adjusted by blowing hot air or the like.

  In the two-stage heat treatment, the heat treatment time for the first stage is preferably 1 to 30 seconds, and the heat treatment time for the second stage is preferably 1 to 30 seconds from the viewpoint of optical uniformity of the film. The heat treatment time for the first stage is further preferably 3 to 20 seconds, particularly preferably 5 to 15 seconds, and the heat treatment time for the second stage is further preferably 3 to 20 seconds. In particular, it is preferably 5 to 15 seconds. If the first heat treatment time is too short, the film tends to be non-uniform, and if it is too long, the film tends to be non-uniform. If the second heat treatment time is too short, the film strength tends to decrease, and if it is too long, the film tends to yellow.

  In the present invention, the object of the present invention can be achieved by the above-described two-stage heat treatment, but if necessary, heat treatment in three or more stages can be performed.

  Thus, the biaxially stretched vinyl alcohol film of the present invention is obtained. The thickness of the biaxially stretched vinyl alcohol film is preferably 5 to 60 μm, particularly 7 to 40 μm, from the viewpoint of the visibility of 3D images. Furthermore, it is preferable that it is 10-30 micrometers. If the thickness is too thin, the strength of the film tends to decrease significantly, and if it is too thick, the visibility of 3D images due to line-of-sight shift tends to decrease.

  In the present invention, the biaxially stretched vinyl alcohol film obtained above is a retardation plate.

Moreover, in this invention, it is preferable that the phase difference value measured with wavelength 540nm of the phase difference plate is 100-160 nm from the point of visibility of 3D image | video, Especially 110-150 nm, Furthermore, it is 115-145 nm. Preferably there is. If the phase difference value is too small or too large, the image tends to be doubled.
Examples of the method of adjusting the retardation value of the retardation plate within the above range include, for example, changing the ratio of the longitudinal draw ratio and the transverse draw ratio, changing the thickness of the film, changing the temperature during stretching, and heat treatment conditions. The method of changing is mentioned.

Furthermore, in the present invention, the Abbe number of the phase difference plate is preferably 40 or more, particularly 50 or more, more preferably 55 or more, from the viewpoint of the visibility of 3D images. If the Abbe number is too small, the color separation ability of 3D video tends to be reduced. The upper limit is usually 250 or less.
Examples of a method for adjusting the Abbe number of the retardation plate within the above range include a method of adjusting a heat treatment temperature, a stretching temperature, a stretching speed, a heat treatment time, and the like.

  In addition, by measuring the Abbe number, the magnitude of the wavelength dispersion of the birefringence phase difference can be confirmed, and thereby, for example, whether the visibility when the polarizing glasses are used is determined. it can.

  Thus, the retardation plate of the present invention can be obtained. The retardation plate of the present invention is used to attach the polarizing plate, and the polarizing plate and the retardation plate are combined with the absorption axis of the polarizing plate and the retardation phase of the retardation plate. Lamination is performed so that the angle with the axis is 45 ° ± 5 °, and a right-eye lens or a left-eye lens can be obtained, and using these, polarized glasses can be obtained.

  That is, the polarized glasses have a right eye lens and a left eye lens worn by an observer when observing a three-dimensional image using circularly polarized light. In the polarized glasses, the right eye lens is a polarizing plate. Including the laminate [I] with the retardation plate, the slow axis of the retardation plate when measured at a wavelength of 540 nm with respect to the absorption axis of the polarizing plate is counterclockwise when viewed from the retardation plate side The left-eye lens includes a laminate [II] of a polarizing plate and a retardation plate, and an absorption axis of the polarizing plate. On the other hand, the phase difference plate was laminated so that the slow axis of the phase difference plate when measuring the phase difference at a wavelength of 540 nm was an angle of 45 ° ± 5 ° clockwise when viewed from the phase difference plate side. Further, a polarizing plate is disposed on the viewer side, and a retardation plate is disposed on the video side.

  In the polarizing glasses, when the observer observes a three-dimensional image, the polarizing plate may be arranged so that the absorption axes of the polarizing plates of the right-eye lens and the left-eye lens are in the vertical direction of the observer's face. preferable.

  Here, by using the retardation plate of the present invention, when the polarizing plate and the retardation plate are laminated to form a circularly polarizing lens for right-eye or left-eye 3D passive glasses, the absorption axis of the polarizing plate The bonding angle with the slow axis of the phase difference plate does not need to be precisely 45 °, and the degree of freedom of the bonding angle is large, as long as it is within the range of 45 ° ± 5 °. In addition, when viewing a 3D image, the polarizing glasses are very excellent in visibility.

  The polarizing glasses obtained as described above have little effect on eye fatigue when viewing 3D images, and have a very excellent effect on visibility, using movies, 3D games, and 3D images. It is expected to be used for digital processing, simulators, and medical applications.

  In addition, as a polarizing plate in the above, the well-known well-known polarizing plate can be used, However, Among these, the polarizing plate using a polyvinyl alcohol-type film is suitable at the point of an optical characteristic or visibility.

  A polarizing plate using a polyvinyl alcohol-based film is a polarizing film produced by subjecting a polyvinyl alcohol-based film to normal dyeing, stretching, boric acid crosslinking, heat treatment, and the like, and optically or the like on one or both sides thereof. An isotropic polymer film or sheet (for example, cellulose triacetate film, polycarbonate, cyclo or norbornene polyolefin) is laminated and adhered as a protective film.

  Such a polarizing plate preferably has a polarization degree of 95% or more and a transmittance of 15% or more, particularly preferably a polarization degree of 98% or more, more preferably 99% or more, and a transmittance of 20%. % Or more, preferably 30% or more.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis.

Example 1
PVA aqueous solution in which 40 parts of PVA (average saponification degree 99.7 mol%, average polymerization degree 1700, 4% aqueous solution viscosity (25 ° C.) 40 mPa · s, sodium acetate content 0.3%) is dissolved in 60 parts of water Was supplied to a twin-screw extrusion kneader (screw L / D = 40) whose jacket temperature was set to 60 to 150 ° C. by a metering pump, and discharged under conditions of a discharge amount of 500 kg / hr. Immediately pump this discharged product to a single screw extruder (screw L / D = 30), knead at a temperature of 85 to 140 ° C., and cast and solidify into a cast roll cooled to 5 ° C. from a T-die, The cooled film was peeled off from the cast roll, and dried for 30 seconds using 10 continuous rotary heating rolls adjusted to 90 ° C. to obtain a PVA film having a thickness of 150 μm and a moisture content of 25%. Subsequently, the PVA film was stretched 3 times in the longitudinal direction, then stretched 3.5 times in the transverse direction with a tenter stretching machine to form a biaxially stretched PVA film, and then heat treated at 145 ° C. for 8 seconds (first stage heat treatment). Subsequently, a heat treatment (second-stage heat treatment) was performed at 180 ° C. for 8 seconds to obtain a retardation plate composed of a biaxially stretched PVA film (thickness: 14 μm) having a water content of 0.8%.
In addition, each temperature of a 1st step heat treatment and a 2nd step heat treatment is an atmospheric temperature when a film passes, and is adjusted by blowing off hot air.
The obtained retardation plate was evaluated as follows.

<Phase difference value at 540 nm>
The retardation value at 540 nm was measured using a retardation measuring device “RETS-100” manufactured by Otsuka Electronics Co., Ltd.

<Abbe number>
The Abbe number was measured using a multi-wavelength Abbe refractometer “DR-M4 / 1550” manufactured by Atago Co., Ltd.

<Pencil hardness>
The pencil hardness was measured according to JIS K-5600.

<Evaluation of 3D video visibility>
The above-obtained retardation plate and a polarizing plate (iodine-stained polarizing plate made of PVA film with a uniaxial stretching ratio of 4.5 times (transmittance 42%, polarization degree 99.9%)) were combined with an acrylic adhesive. Agent (acrylic resin (“Coponil N-7429” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 100 parts, silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) Coronate L55E ") was bonded via an acrylic pressure-sensitive adhesive composed of 0.6 parts (thickness after drying was 25 µm)). At the time of bonding, the retardation plate is laminated so that the slow axis of the retardation plate is at an angle of 48 ° counterclockwise when viewed from the retardation plate side with respect to the absorption axis of the polarizing plate, A circular polarizing lens for the right eye was produced. Similarly, a circularly polarizing lens for the left eye was manufactured by laminating so that the slow axis of the retardation plate obtained above and the absorption axis of the polarizing plate were at an angle of 42 ° clockwise.
The right-eye circular polarization lens and the left-eye circular polarization lens obtained above are arranged so that the polarizing plate is arranged on the viewer side, and when the viewer observes the three-dimensional image, the right-eye lens and the left-eye lens are arranged. 3D polarizing glasses are obtained by fixing to a spectacle frame so that the absorption axis of the polarizing plate of the lens for the observer is in the vertical direction of the face of the observer, using LG FPR 3D-TV (32LW5700), The visibility of 3D video was evaluated.

Examples 2-3 and Comparative Examples 1-3
As shown in Table 1, in Example 1, it carried out similarly except having changed the heat processing conditions of a biaxially stretched PVA-type film, and obtained the phase difference plate.
The obtained retardation plate was evaluated in the same manner as in Example 1.
The evaluation results of Examples and Comparative Examples are shown in Table 1.

  From the results of the above Examples and Comparative Examples, for Examples 1 to 3, a favorable Abbe number and visibility were obtained while being at a predetermined bonding angle, whereas the heat treatment conditions were In each of Comparative Examples 1 and 2 that deviated from the predetermined condition, the Abbe number was inferior to that of the example, and the visibility was not satisfactory. Moreover, in Examples 1-3, although all are excellent in surface hardness, in Comparative Example 3, it is inferior in surface hardness, and in the case of the bonding with a polarizing film, and the conveyance process of a film There was a possibility that scratches caused by rubbing with the roll might be a problem, and it was not satisfactory. Further, the visibility in Comparative Example 3 was insufficient.

  The retardation plate obtained by the production method of the present invention has, for example, less eye fatigue when viewing 3D images, and has a very excellent effect on visibility. It is highly expected for digital processing using 3D images, simulators, and medical applications.

Claims (6)

A method for producing a retardation plate comprising a biaxially stretched vinyl alcohol film, wherein the biaxially stretched vinyl alcohol film is heat treated in at least two stages, and the first stage heat treatment temperature is 130 to 180 ° C. A method for producing a phase difference plate, wherein the heat treatment temperature of the eye is 160 to 210 ° C., and the heat treatment temperature of the second stage is higher by 5 ° C. than the heat treatment temperature of the first stage. 2. The method for producing a retardation film according to claim 1, wherein the biaxially stretched vinyl alcohol film is a stretched film obtained by sequential biaxial stretching in which transverse uniaxial stretching is performed after longitudinal uniaxial stretching. 3. The method for producing a retardation plate according to claim 1, wherein the heat treatment time for the first stage is 1 to 30 seconds and the heat treatment time for the second stage is 1 to 30 seconds. The biaxially stretched vinyl alcohol film is a stretched film having a stretch ratio of 1.5 to 4.5 times in the longitudinal direction and a stretch ratio of 1.5 to 4.5 times in the transverse direction. The manufacturing method of the phase difference plate in any one of -3. The method for producing a retardation plate according to any one of claims 1 to 4, wherein the saponification degree of the vinyl alcohol resin constituting the biaxially stretched vinyl alcohol film is 90 mol% or more. The thickness of a biaxially stretched vinyl alcohol-type film is 5-60 micrometers, The manufacturing method of the phase difference plate in any one of Claims 1-5 characterized by the above-mentioned.